A flame retardant, a preparation method thereof, and its application in recycled flame-retardant PET foam material

Abstract

The present invention discloses a flame retardant, a preparation method thereof, and application thereof in a recycled flame-retardant PET foam material, belonging to the technical field of polymer materials. The flame retardant has a structural formula as shown in Formula I. The flame retardant of the present invention contains N and P elements in its molecular structure and has good flame retardant properties. The molecular structure of the flame retardant also contains multiple hydroxyl groups, which enable it to play a branching role in the polymerization reaction. When added to a PET material, the flame retardant can effectively improve the flame retardant properties. At the same time, since the hydroxyl groups contained in the flame retardant can undergo an esterification reaction with the carboxyl groups in the polyester, it can play a branching role, increase the viscosity and molecular weight of the material, and improve the mechanical properties of the PET. The recycled flame-retardant PET foam material of the present invention contains N and P elements in its molecular structure, has a high molecular branching degree and a high molecular weight, and has excellent flame retardant properties, mechanical properties, and viscosity.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a flame retardant, a preparation method thereof, and application of the flame retardant in recycled flame-retardant PET foaming materials. Background Art

[0002] With the rapid development of science and technology, various plastics have been developed and applied in various industries. Among them, polyethylene terephthalate (PET) has played a pivotal role in the plastics industry since its invention in the last century. PET's ability to maintain good mechanical properties, high transparency, and excellent insulation properties over a wide temperature range have led to its application in packaging, clothing fibers, food containers, and other industries. As a foam material, PET has excellent dimensional stability, good sound and heat insulation, high heat resistance, and good barrier properties against water vapor, oxygen, and carbon dioxide. Its mechanical properties and fatigue resistance are excellent, but PET has a limiting oxygen index of 20.6%, making it a flammable material. In the event of a fire, it is highly flammable, potentially causing significant economic losses and casualties.

[0003] Currently, researchers are primarily adding flame retardants to increase the limiting oxygen index (LOI) of PET polyester, improving its flame retardancy and expanding its application. Currently, there are two types of flame retardants: additive and reactive. Additive flame retardants are widely used due to their ease of use, wide variety, and ease of application. However, their disadvantages are that high addition levels can lead to agglomeration and uneven dispersion. Furthermore, large amounts of flame retardants can also affect the mechanical properties of the material, leading to unsatisfactory preparation results. Reactive flame retardants use chemical reactions to introduce flame-retardant elements or functional groups into the chemical structure, imparting a certain degree of flame resistance. This method fundamentally addresses the material's flammability. Halogenated flame retardants, primarily brominated flame retardants, were once popular in flame-retardant materials. These compounds produce dioxins upon combustion, which are extremely harmful to humans and the environment. Their use is now gradually declining. Halogen-free flame retardants, primarily containing elements such as phosphorus, nitrogen, and silicon, are low-toxic and low-polluting, and their addition can significantly improve the flame retardancy of materials. Currently, phosphorus-based flame retardants are primarily DOPO derivatives, while nitrogen-based flame retardants are primarily melamine compounds. Developing a highly effective flame retardant while maintaining the inherent performance of the material has become a pressing technical challenge for those skilled in the art.

[0004] CN113372875A discloses a bio-based adhesive, its preparation method, and application. The bio-based core-shell flame-retardant particles are prepared by adding a flame retardant to a mixture containing a silane coupling agent and an acid-binding agent, mixing and modifying the mixture to obtain a product A; then mixing tannic acid with the product A to obtain the bio-based core-shell flame-retardant particles after modification. However, its application in artificial boards still requires improvement in terms of flame retardancy. Its limiting oxygen index is improved by 28.6%, while the bio-based core-shell flame-retardant particles only improve flame retardancy by 3% (comparison between Example 6 and Comparative Example 2). Furthermore, its addition significantly reduces viscosity. The preparation method is complex, requiring modification with tannic acid and a coupling agent. Furthermore, because diethylamine is used, its molecular structure does not contain hydroxyl groups.

[0005] Currently, the existing technology for preparing recycled PET polyester into foam materials mainly uses physical methods. During the extrusion process, a large amount of chain extenders are generally added to modify the material to increase the intrinsic viscosity of the melt. If flame retardant properties are to be obtained, a large amount of flame retardants must also be added to ensure the flame retardancy of the foam material. However, the large amount of flame retardants and chain extenders added will change the mechanical properties of the material. Excessive additives are prone to agglomeration and uneven dispersion, resulting in unstable flame retardant properties of the material, thereby affecting the use of the material. Chemical methods can be used to hydrolyze the recycled PET polyester and then re-condense it. The addition of branching agents and reactive flame retardants during the preparation process can expand the PET molecular chain. At the same time, flame retardant elements such as P, N, and Si are added to the molecular chain to ensure that the recycled polyester material has a high molecular weight and a certain degree of flame retardant properties. The material also contains a low content of additives, which has little impact on the mechanical properties of the material. For example, CN114805775A discloses a recycled flame-retardant PET foam material. This uses an additive-type phosphorus and nitrogen flame retardant, which has a large addition amount and poor dispersion performance, requiring the addition of branching agents and nucleating agents. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a flame retardant and a preparation method thereof and the use thereof in a recycled flame-retardant PET foam material. The flame retardant contains N and P elements in its molecular structure and also contains polyhydroxyl groups. When added to a PET material, the flame retardant can effectively improve the flame retardant performance. At the same time, because the flame retardant contains hydroxyl groups, it can undergo an esterification reaction with the carboxyl groups in the polyester, thereby achieving a branching effect, increasing the viscosity and molecular weight of the material, and improving the mechanical properties of the PET.

[0007] To achieve the above objectives, in a first aspect of the present invention, the present invention provides a flame retardant, the structural formula of which is shown in Formula I:

[0008]

[0009] In the second aspect of the present invention, the present invention provides a method for preparing the flame retardant described above, wherein the flame retardant is prepared by reacting diethanolamine and phenylphosphoryl dichloride as raw materials in the presence of a solvent and an acid binding agent;

[0010] The molar ratio of the diethanolamine to phenylphosphoryl dichloride is 2:(0.8-1.2).

[0011] As a preferred embodiment of the present invention, the acid binding agent includes at least one of triethylamine, pyridine, and N,N-diisopropylethylamine; and / or

[0012] The solvent includes at least one of dichloromethane, chloroform, carbon tetrachloride, trichloroethane, and phenylphosphoryl dichloride.

[0013] As a preferred embodiment of the present invention, the following steps are included:

[0014] Diethanolamine, an acid binding agent, and part of the solvent are mixed uniformly to obtain a first premix;

[0015] Mixing phenylphosphoryl dichloride with another portion of the solvent to obtain a second premix;

[0016] The second premix is ​​added dropwise to the first premix, the reaction is completed, filtered, washed, and dried to obtain a flame retardant.

[0017] In the third aspect of the present invention, the present invention provides the use of the flame retardant described above in the preparation of a flame retardant PET foam material.

[0018] In a fourth aspect of the present invention, the present invention provides a recycled flame-retardant PET foam material, the structural formula of which is shown in Formula II:

[0019]

[0020] Where Y is 50 to 150.

[0021] As a preferred embodiment of the present invention, the preparation raw materials include the following mass percentages: 4-60% recycled PET polyester, 26-80.4% terephthalic acid, 13.1-64.6% ethylene glycol, 0.01-0.05% catalyst, and 0.08-7% flame retardant;

[0022] The flame retardant is the flame retardant described above.

[0023] As a preferred embodiment of the present invention, the intrinsic viscosity of the recycled PET polyester is ≤1 dl / g; and / or

[0024] The catalyst comprises at least one of n-butyl titanate, titanium glycolate, cobalt acetate, germanium dioxide antimony acetate, antimony glycolate, antimony trioxide, tetrabutoxygermanium, butylstannoic acid, stannous octoate and germanium dioxide.

[0025] As a preferred embodiment of the present invention, the following raw materials are further included in the preparation in percentage by mass: 0.01 to 0.8% of a stabilizer, 0.01 to 1% of an antioxidant, and 0 to 0.01% of a toner.

[0026] As a preferred embodiment of the present invention, the stabilizer includes at least one of phosphorous acid, trimethyl phosphite, triethyl phosphite, and triphenyl phosphite; and / or

[0027] The antioxidant includes at least one of antioxidant 1010, antioxidant 1076, and antioxidant 1035; and / or

[0028] The toner includes at least one of phthalocyanine blue pigment, phthalocyanine green pigment, basic blue dye, phthalocyanine pigment, anthraquinone pigment, and cadmium red pigment.

[0029] In a fifth aspect of the present invention, the present invention provides a method for preparing a recycled flame-retardant PET foam material, comprising the following steps:

[0030] The recycled PET polyester is added to a reactor, terephthalic acid, ethylene glycol, a catalyst, a flame retardant, a stabilizer, an antioxidant, and a toner are prepared into a slurry, and the slurry is added to the reactor for esterification reaction;

[0031] When the water extraction rate reaches 90%, the esterification reaction is completed, and the polycondensation reaction is carried out to obtain PET melt, which is then extruded, cooled, pelletized and dried to obtain PET chips;

[0032] The PET slices are subjected to a solid phase polycondensation reaction to obtain recycled PET polyester, the recycled PET polyester is dried, and a twin-screw extruder is used to extrude and foam the recycled flame-retardant PET foam material.

[0033] The beneficial effects of the present invention are: (1) The flame retardant of the present invention contains N and P elements in its molecular structure, has good flame retardant properties, and also contains multiple hydroxyl groups in its molecular structure, so that it can play a branching role in the polymerization reaction; adding it to the PET material can effectively improve the flame retardant properties, and at the same time, because it contains hydroxyl groups, it can undergo esterification reaction with the carboxyl groups in the polyester, play a branching role, increase the viscosity and molecular weight of the material, and improve the mechanical properties of PET; (2) The recycled flame retardant PET foam material of the present invention contains N and P elements in its molecular structure, has a high molecular branching degree and a high molecular weight, and the recycled flame retardant PET foam material has excellent flame retardant properties, mechanical properties and viscosity. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0036] As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items. "Or" means "and / or". As used herein, the singular forms "a, an" and "the" are intended to include plural forms, including "at least one", unless the content clearly indicates otherwise. "At least one" should not be interpreted as limiting "one". Expressions such as "at least one of..." when before or after a list of elements modify the entire list of elements without modifying the individual elements of the list. It will be further understood that the terms "include" or "comprise" when used in this specification indicate the presence of the stated features, regions, wholes, steps, operations, elements (elements), and / or components, but do not exclude the presence or addition of one or more additional features, regions, wholes, steps, operations, elements (elements), components, and / or their collections.

[0037] In the present invention, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Furthermore, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0038] In the present invention, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0039] The reagents and instruments used in the present invention without indicating the manufacturer are all conventional products that can be purchased from the market.

[0040] The invention aims to solve the problem of poor flame retardancy and mechanical properties of existing recycled PET foam materials.

[0041] An embodiment of the present invention provides a flame retardant, the structural formula of which is shown in Formula I:

[0042]

[0043] The flame retardant shown in Formula I contains N and P elements in its molecular structure and has good flame retardant properties. Its molecular structure also contains multiple hydroxyl groups, which can play a branching role in the polymerization reaction. Adding it to PET material can effectively improve the flame retardant properties. At the same time, because it contains hydroxyl groups, it can undergo esterification reaction with the carboxyl groups in polyester, which can play a branching role, increase the viscosity and molecular weight of the material, and improve the mechanical properties of PET.

[0044] One embodiment of the present invention provides a method for preparing the flame retardant described above, wherein diethanolamine and phenylphosphoryl dichloride are reacted as raw materials in the presence of a solvent and an acid binding agent;

[0045] The molar ratio of the diethanolamine to phenylphosphoryl dichloride is 2:(0.8-1.2).

[0046] The present invention creatively uses diethanolamine and phenylphosphoryl dichloride as raw materials in the presence of a solvent and an acid binding agent to synthesize the flame retardant represented by the above formula I. The preparation method is simple and has broad application prospects.

[0047] In one embodiment, the molar ratio of diethanolamine to phenylphosphoryl dichloride is 2:1.

[0048] The formula for synthesizing the flame retardant represented by Formula I is shown in Reaction 1.

[0049]

[0050] Exemplarily, the acid binding agent includes at least one of triethylamine, pyridine, and N,N-diisopropylethylamine.

[0051] Illustratively, the solvent includes at least one of dichloromethane, chloroform, carbon tetrachloride, trichloroethane, and phenylphosphinoyl dichloride.

[0052] In one embodiment, the method for preparing the flame retardant comprises the following steps:

[0053] Diethanolamine, an acid binding agent, and part of the solvent are mixed uniformly to obtain a first premix;

[0054] Mixing phenylphosphoryl dichloride with another portion of the solvent to obtain a second premix;

[0055] The second premix is ​​added dropwise to the first premix, the reaction is completed, filtered, washed, and dried to obtain a flame retardant.

[0056] One embodiment of the present invention provides a use of the flame retardant described above in preparing a flame-retardant PET foam material.

[0057] One embodiment of the present invention provides a recycled flame retardant PET foam material, the structural formula of which is shown in Formula II.

[0058]

[0059] Where Y is 50 to 150.

[0060] The recycled flame-retardant PET foam material shown in Formula II contains N and P elements in its molecular structure, has a high molecular branching degree and a high molecular weight, and has excellent flame retardant properties, mechanical properties and viscosity.

[0061] In one embodiment, the preparation comprises the following raw materials in percentage by weight: 4-60% recycled PET polyester, 26-80.4% terephthalic acid, 13.1-64.6% ethylene glycol, 0.01-0.05% catalyst, and 0.08-7% flame retardant;

[0062] The flame retardant is the flame retardant described above.

[0063] In one embodiment, the recycled PET polyester has an intrinsic viscosity of ≤1 dl / g. The recycled PET polyester can be PET chips, bottle flakes, fibers, etc., and must be clean, free of contaminants such as ink, labels, or other components, as long as its intrinsic viscosity is within 1.0 dl / g.

[0064] Exemplarily, the catalyst includes at least one of n-butyl titanate, titanium glycolate, cobalt acetate, germanium dioxide antimony acetate, antimony glycolate, antimony trioxide, tetrabutoxygermanium, butylstannoic acid, stannous octoate, and germanium dioxide.

[0065] In one embodiment, the invention further comprises the following raw materials in the following weight percentages: 0.01 to 0.8% of a stabilizer, 0.01 to 1% of an antioxidant, and 0 to 0.01% of a toner.

[0066] In one embodiment, the stabilizer includes at least one of phosphorous acid, trimethyl phosphite, triethyl phosphite, and triphenyl phosphite. The stabilizer can inhibit the catalytic degradation of the metal catalyst, improve the thermal stability of PET polyester, increase its melting temperature, and avoid agglomeration during solid-phase polycondensation, thereby effectively improving the quality of the polyester. The phosphorous acid stabilizer can be used in conjunction with some antioxidants to improve the material's antioxidant properties.

[0067] In one embodiment, the antioxidant includes at least one of antioxidant 1010, antioxidant 1076, and antioxidant 1035. The antioxidant can inhibit the oxidation reaction of the polyester material and increase the service life of the PET polyester material. Such antioxidants can be used in conjunction with phosphite stabilizers to improve the material's antioxidant properties.

[0068] In one embodiment, the colorant includes at least one of phthalocyanine blue pigment, phthalocyanine green pigment, basic blue dye, phthalocyanine pigment, anthraquinone pigment, and cadmium red pigment. Such colorants are non-toxic and harmless to the human body. The color of the polyester material can be changed by changing the proportion of different regulators, making its application more extensive.

[0069] One embodiment of the present invention provides a method for preparing a recycled flame-retardant PET foam material, comprising the following steps:

[0070] The recycled PET polyester is added to a reactor, terephthalic acid, ethylene glycol, a catalyst, a flame retardant, a stabilizer, an antioxidant, and a toner are prepared into a slurry, and the slurry is added to the reactor for esterification reaction;

[0071] When the water extraction rate reaches 90%, the esterification reaction is completed, and the polycondensation reaction is carried out to obtain PET melt, which is then extruded, cooled, pelletized and dried to obtain PET chips;

[0072] The PET slices are subjected to a solid phase polycondensation reaction to obtain recycled PET polyester, the recycled PET polyester is dried, and a twin-screw extruder is used to extrude and foam the recycled flame-retardant PET foam material.

[0073] It should be noted that the foaming method is a conventional foaming method in the art, for example, using CO2 or N2 as the foaming gas.

[0074] The above-mentioned recycled flame-retardant PET foam material is firstly subjected to alcoholysis, then to polycondensation reaction with a flame retardant, solid phase polycondensation reaction, and finally the prepared particles are extruded and foamed. The synthesis process is as follows:

[0075]

[0076]

[0077] The following examples are provided to facilitate understanding of the present invention. These examples are not provided to limit the scope of the claims.

[0078] Example 1

[0079] A method for preparing a flame retardant comprises the following steps:

[0080] (1) Mix 210.27 g of diethanolamine, 202.38 g of triethylamine, and 600 ml of dichloromethane, place them in a 2000 ml three-necked flask, and place the three-necked flask in an ice-water bath;

[0081] (2) 194.98 g of phenylphosphoryl dichloride (the molar ratio of diethanolamine to phenylphosphoryl dichloride is 2:1) was taken and mixed evenly with 400 ml of dichloromethane to obtain a mixed solution, which was added dropwise to a three-necked flask. After the addition was completed, the mixture was mechanically stirred at 25°C for 6 hours, and then the temperature was continuously raised to 120°C, refluxed for 10 hours, and filtered to obtain a solid. The filtered solid was washed three times with a saturated sodium bicarbonate solution and hot water, respectively, and finally dried in vacuo at 80°C to obtain a flame retardant.

[0082] The structural formula of the flame retardant is shown in Formula I:

[0083]

[0084] Example 2

[0085] A recycled flame-retardant PET foam material comprises the following raw materials in percentage by mass: 3500 g of recycled PET polyester, 5317.2 g of terephthalic acid, 2780.3 g of ethylene glycol, 2.5 g of a catalyst, 350 g of a flame retardant, 5 g of an antioxidant, 2.3 g of a stabilizer, and 0.2 g of a toner.

[0086] The flame retardant is the flame retardant prepared in Example 1, the catalyst is ethylene glycol antimony, the antioxidant is antioxidant 1010, the stabilizer is trimethyl phosphite, and the toner is anthraquinone blue.

[0087] The intrinsic viscosity of the recycled PET polyester is 0.82 dl / g.

[0088] The preparation method of the recycled flame-retardant PET foam material comprises the following steps:

[0089] (1) Recycled PET polyester is added to a reactor, and terephthalic acid, ethylene glycol, a catalyst, a stabilizer, an antioxidant, and a toner are uniformly mixed to form a slurry, which is then added to the reactor to carry out an esterification reaction; the esterification reaction is carried out under a nitrogen atmosphere, at a pressure of 0.4 MPa, at a temperature of 240° C., and for 1.5 hours;

[0090] (2) When the water yield reaches 90%, the esterification reaction is completed, and a polycondensation reaction is carried out to obtain a PET melt, which is then extruded, cooled, pelletized, and dried to obtain PET chips. The polycondensation reaction is divided into two stages: in stage 1, the vacuum degree of the polycondensation reaction is 400 Pa, the temperature of the polycondensation reaction is 260°C, and the time of the polycondensation reaction is 1 hour; in stage 2, the vacuum degree of the polycondensation reaction is 60 Pa, the temperature of the polycondensation reaction is 280°C, and the time of the polycondensation reaction is 3 hours;

[0091] (3) subjecting the PET chips to a solid-phase polycondensation reaction to obtain the regenerated PET polyester; the specific process of the solid-phase polycondensation reaction is: placing the PET chips into a rotating drum, the drum temperature is 220° C., the vacuum degree is below 100 Pa, and the solid-phase polycondensation reaction time is 30 hours.

[0092] (4) drying the recycled PET polyester, and extruding and foaming the recycled flame-retardant PET polyester using a twin-screw extruder to obtain the recycled flame-retardant PET foam material.

[0093] The prepared recycled flame-retardant PET foam material has a structural formula as shown in Formula II:

[0094]

[0095] Where Y is 50 to 150.

[0096] Example 3

[0097] The difference between Example 3 and Example 2 is that the raw material ratio is different, and everything else is the same.

[0098] A recycled flame-retardant PET foam material comprises the following raw materials in percentage by mass: 500 g of recycled PET polyester, 7910.9 g of terephthalic acid, 3545.6 g of ethylene glycol, 2.5 g of a catalyst, 350 g of a flame retardant, 5 g of an antioxidant, 2.3 g of a stabilizer, and 0.2 g of a toner.

[0099] Example 4

[0100] The difference between Example 4 and Example 2 is that the raw material ratio is different, and everything else is the same.

[0101] A recycled flame-retardant PET foam material comprises the following raw materials in percentage by mass: 6000 g of recycled PET polyester, 3155.7 g of terephthalic acid, 2357.3 g of ethylene glycol, 2.5 g of a catalyst, 350 g of a flame retardant, 5 g of an antioxidant, 2.3 g of a stabilizer, and 0.2 g of a toner.

[0102] Example 5

[0103] The difference between Example 5 and Example 2 is that the amount of flame retardant is different, and the other aspects are the same.

[0104] A recycled flame-retardant PET foam material comprises the following raw materials in percentage by mass: 3500 g of recycled PET polyester, 5317.2 g of terephthalic acid, 2780.3 g of ethylene glycol, 2.5 g of a catalyst, 10 g of a flame retardant, 5 g of an antioxidant, 2.3 g of a stabilizer, and 0.2 g of a toner.

[0105] Example 6

[0106] The difference between Example 6 and Example 2 is that the raw material ratio is different, and everything else is the same.

[0107] A recycled flame-retardant PET foam material comprises the following raw materials in percentage by mass: 3500 g of recycled PET polyester, 4928.13 g of terephthalic acid, 2576.88 g of ethylene glycol, 2.5 g of a catalyst, 800 g of a flame retardant, 5 g of an antioxidant, 2.3 g of a stabilizer, and 0.2 g of a toner.

[0108] Comparative Example 1

[0109] The difference between Comparative Example 1 and Example 2 is that no flame retardant is added in Comparative Example 1, and all other aspects are the same.

[0110] Comparative Example 2

[0111] The difference between Comparative Example 2 and Example 2 is that the flame retardant is replaced by an equal weight of pyromellitic anhydride in Comparative Example 2, and all other conditions are the same.

[0112] Comparative Example 3

[0113] The difference between Comparative Example 3 and Example 2 is that, in the preparation method of the flame retardant described in Comparative Example 3, an equal molar amount of ethylenediamine (120.2 g) is used to replace diethanolamine, and the other conditions are the same.

[0114] Test Case

[0115] 1. Recycled PET polyester test: The viscosity and tensile strength of recycled PET polyester are tested in accordance with GB / T 1040.1.

[0116] 2. Recycled flame-retardant foamed PET material: Test the limiting oxygen index according to GB / T 2046.2; test the tensile strength according to GB / T6344.

[0117] The test results are shown in Table 1.

[0118] Table 1

[0119]

[0120]

[0121] As can be seen from Table 1, the recycled flame-retardant PET foam material of the present invention has excellent flame retardant properties, mechanical properties, and high viscosity.

[0122] By comparing Example 2 with Comparative Example 1, it can be seen that the addition of the flame retardant of the present invention significantly improves the flame retardancy, mechanical properties and viscosity of the PET foam material.

[0123] Comparison of Example 2 and Comparative Example 2 shows that using a branching agent (pyromellitic anhydride) to replace the flame retardant of the present invention will lead to a significant decrease in flame retardancy, mechanical properties and viscosity.

[0124] By comparing Example 2 with Comparative Example 3, it can be seen that in the preparation of the flame retardant, if ethylenediamine is used to replace diethanolamine, it can only play a flame retardant role but not a branching role, and the flame retardant effect is also significantly reduced.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A recycled flame-retardant PET foam material, characterized in that: Its structural formula is shown in Formula II: Wherein Y is 50 to 150; The recycled flame-retardant PET foam material comprises the following raw materials in percentage by mass: 4-60% recycled PET polyester, 26-80.4% terephthalic acid, 13.1-64.6% ethylene glycol, 0.01-0.05% catalyst, and 0.08-7% flame retardant; The flame retardant structural formula is shown in Formula I:

2. The recycled flame-retardant PET foam material according to claim 1, characterized in that: The intrinsic viscosity of the recycled PET polyester is ≤1 dl / g; and / or The catalyst comprises at least one of n-butyl titanate, titanium glycolate, cobalt acetate, germanium dioxide antimony acetate, antimony glycolate, antimony trioxide, tetrabutoxygermanium, butylstannoic acid, stannous octoate and germanium dioxide.

3. The recycled flame-retardant PET foam material according to claim 1, characterized in that: The invention also includes the following raw materials in percentage by weight: 0.01 to 0.8% of a stabilizer, 0.01 to 1% of an antioxidant, and 0 to 0.01% of a toner.

4. The recycled flame-retardant PET foam material according to claim 3, characterized in that: The stabilizer comprises at least one of phosphorous acid, trimethyl phosphite, triethyl phosphite, and triphenyl phosphite; and / or The antioxidant includes at least one of antioxidant 1010, antioxidant 1076, and antioxidant 1035; and / or The toner includes at least one of phthalocyanine blue pigment, phthalocyanine green pigment, basic blue dye, phthalocyanine pigment, anthraquinone pigment, and cadmium red pigment.

5. The recycled flame-retardant PET foam material according to claim 1, characterized in that: The flame retardant is prepared by reacting diethanolamine and phenylphosphoryl dichloride as raw materials in the presence of a solvent and an acid binding agent; The molar ratio of the diethanolamine to phenylphosphoryl dichloride is 2:(0.8-1.2).

6. The method for preparing a flame retardant according to claim 5, wherein: The acid binding agent comprises at least one of triethylamine, pyridine, and N,N-diisopropylethylamine; and / or The solvent includes at least one of dichloromethane, chloroform, carbon tetrachloride, trichloroethane, and phenylphosphoryl dichloride.

7. The method for preparing a flame retardant according to claim 5, wherein: The following steps are involved: Diethanolamine, an acid binding agent, and part of the solvent are mixed uniformly to obtain a first premix; Mixing phenylphosphoryl dichloride with another portion of the solvent to obtain a second premix; The second premix is ​​added dropwise to the first premix, the reaction is completed, filtered, washed, and dried to obtain a flame retardant.

8. The method for preparing the recycled flame-retardant PET foam material according to claim 4, characterized in that: The following steps are involved: The recycled PET polyester is added to a reactor, terephthalic acid, ethylene glycol, a catalyst, a flame retardant, a stabilizer, an antioxidant, and a toner are prepared into a slurry, and the slurry is added to the reactor for esterification reaction; When the water extraction rate reaches 90%, the esterification reaction is completed, and the polycondensation reaction is carried out to obtain PET melt, which is then extruded, cooled, pelletized and dried to obtain PET chips; The PET slices are subjected to a solid phase polycondensation reaction to obtain recycled PET polyester, the recycled PET polyester is dried, and a twin-screw extruder is used to extrude and foam the recycled flame-retardant PET foam material.

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