A high and low temperature resistant flame retardant for polyester, preparation method thereof and application thereof

Abstract

The present invention provides a high and low temperature resistant flame retardant for polyester, a preparation method thereof and an application thereof. The high and low temperature resistant flame retardant for polyester comprises the following raw materials: phenylphosphonitrile compounds, hydroxypyrazine compounds, and concentrated sulfuric acid. The functionality of the phenylphosphonitrile compounds is 1, and the hydroxypyrazine compounds are 2 or 3. In the present invention, phenylphosphonitrile compounds and hydroxypyrazine compounds are used as raw materials, and an alcoholysis to ester reaction of nitrile groups occurs under the catalytic action of concentrated sulfuric acid. The product has good compatibility with PET, can efficiently flame retard without causing too much damage to the mechanical properties of PET, and the PET composite material containing this flame retardant has excellent high and low temperature cycle aging performance. The flame retardant synthesized in the present invention has good thermal stability, does not release harmful gases during the flame retardant process, and good flame retardant effects can be achieved by adding a small amount. The preparation method of the present invention is simple and suitable for large-scale production and use.

Description

Technical Field

[0001] The present invention belongs to the technical field of flame retardants, and particularly relates to a high and low temperature resistant flame retardant for polyester, a preparation method thereof, and an application thereof. Background Art

[0002] Polyester, such as polyethylene terephthalate (PET), is a crystalline polymer with resistance to chemical reagents, good thermal stability, high strength, high transparency, and good spinnability. As a thermoplastic resin, PET has become the fifth largest engineering plastic after nylon, polycarbonate, polyoxymethylene, and polyphenylene ether, and is widely used in the fields of medical and health, electronics and electrical appliances, construction, automobiles, packaging industry, etc. Packaging is the largest non-fiber application market for polyester and also the fastest growing polyester application field in recent years. At present, with the continuous increase in the demand for plastic food packaging, the production and application of polyester packaging materials are developing at an unprecedented speed. Among them, especially PET-based packaging materials are developing towards a wide range of applications with strong competitiveness and great vitality as a rising star.

[0003] Generally, during the combustion process of polyester plastics, there are often flames and a large number of dripping substances with or without flames, which can easily cause the surrounding combustibles to catch fire, leading to "secondary combustion", expanding the scope of the fire and its spread. The dripping substances can also easily burn people's skin. The oxygen index is only 20 - 22%. With the improvement of people's living standards, various national organizations have successively put forward higher requirements for the flame retardancy of polyester plastics. Currently, the flame retardants with better flame retardant effects on polyester are phosphorus / nitrogen-based additive flame retardants, including melamine cyanurate, melamine polyphosphate, ammonium polyphosphate, etc. For example, Patent CN201610547345.8 discloses a flame-retardant polyethylene terephthalate system and its preparation method. The flame-retardant PET system includes PET and an intumescent flame retardant. The intumescent flame retardant includes an acid source, a carbon source / gas source. Among them, the acid source is ammonium polyphosphate, and the carbon source / gas source is an ester synthesized from tris(2-hydroxyethyl) isocyanurate and an organic acid. Patent CN201410508022.9 discloses a triazine triphenylphosphine acid secondary butyl ester flame retardant composition and its application method. The flame retardant composition is prepared by compounding and uniformly mixing any two, three, or four of melamine cyanurate (abbreviation: MCA), melamine polyphosphate (abbreviation: MPP), 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (abbreviation: DOPO), and pentaerythritol methyl silicate (abbreviation: PEMS) with triazine triphenylphosphine acid secondary butyl ester (abbreviation: TTPS) in any proportion, and the weight fraction of TTPS is greater than zero. It can be used as a flame retardant for materials such as polyester PET. The above-mentioned existing technologies are all phosphorus / nitrogen-based additive flame retardants for flame retardant modification of PET. They can not only play a flame retardant role on PET but also have the advantage of being able to flexibly match and use other flame retardants or smoke suppressants according to specific situations. However, it is not difficult to find that the compatibility between the above-mentioned flame retardants and PET is poor, which not only causes great damage to the mechanical properties of PET, but also because some PET packaging materials often experience high and low temperature scenarios, the flame retardant is prone to migration, resulting in uneven distribution of the flame retardant in the packaging material, which is not conducive to flame retardancy.

[0004] Therefore, developing a flame retardant that has good compatibility with polyester, can efficiently retard fire without causing excessive damage to the mechanical properties of polyester, and especially can still keep the material having good flame retardant performance when the polyester flame retardant material undergoes high and low temperature cyclic aging is of great significance to the safety of human life and property and the application of polyester in the field of packaging materials. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a high and low temperature resistant flame retardant for polyester, its preparation method and application. The present invention uses phenylphosphonitrile compounds and hydroxypyrazine compounds as raw materials, and undergoes an alcoholysis to ester reaction of nitrile groups under the catalytic action of concentrated sulfuric acid. The product has good compatibility with polyester, and the polyester composite material containing this flame retardant has excellent high and low temperature cyclic aging performance.

[0006] To achieve the above object, the following specific technical solutions are adopted:

[0007] A high and low temperature resistant flame retardant for polyester, the high and low temperature resistant flame retardant for polyester comprising the following raw materials: phenylphosphonitrile compounds, hydroxypyrazine compounds, concentrated sulfuric acid, the functionality of the phenylphosphonitrile compounds being 1, and the hydroxypyrazine compounds being 2-functional hydroxypyrazine compounds and / or 3-functional hydroxypyrazine compounds.

[0008] Further, the molar ratio of nitrile groups to hydroxyl groups in the phenylphosphonitrile compounds and hydroxypyrazine compounds is 1.14 - 1.26:1, the molar ratio of H 2 SO 4 in the concentrated sulfuric acid to the hydroxyl groups in the hydroxypyrazine compounds is 1.25 - 1.45:1, and the concentration of the concentrated sulfuric acid is 93 - 98 wt%.

[0009] Because concentrated sulfuric acid serves both as a salt-forming agent and a catalyst for small molecule product NH 3 during the reaction process, the amount of concentrated sulfuric acid used is relatively large, and too little will result in too low a yield.

[0010] The 2-functional hydroxypyrazine compounds are selected from one or more of 2,3-pyrazinedimethanol, 2,5-pyrazinediethanol, 3,6-dimethyl-2,5-pyrazinedimethanol, 3-ethyl-2,5-pyrazinediethanol, 2,2'-(3-methyl-2,5-pyrazinediyl)diethanol;

[0011] The 3-functional hydroxypyrazine compounds are (6-methyl-2,3,5-pyrazinetriyl)trimethanol, 1-[5-(2-hydroxyethyl)-2-pyrazinyl]-1,2-ethanediol.

[0012] Preferably, the hydroxypyrazine compounds are 3-functional hydroxypyrazine compounds.

[0013] The phenylphosphonitrile compounds are selected from one or more of (diphenylphosphoryl)acetonitrile, (diphenylphosphoryl)propanenitrile, 4-cyanophenyl ethyl p-phenylphosphonate, (3-cyanophenyl)-diethyl phosphate, 4-cyanophenyl diethyl phosphite, dimethyl 4-cyanophenyl phosphate.

[0014] Preferably, the phenylphosphonitrile compounds are selected from one or more of (diphenylphosphoryl)acetonitrile, (diphenylphosphoryl)propanenitrile, 4-cyanophenyl ethyl p-phenylphosphonate.

[0015] The phenylphosphazene compound and the hydroxypyrazine compound undergo an alcoholysis reaction of nitrile groups to form esters under the catalysis of concentrated sulfuric acid. The inventors found that the compatibility between the flame retardant and PET can be adjusted by adjusting factors such as the functionality of the reaction raw materials and the types of raw materials. In particular, the flame retardant obtained from the preferred embodiments of the present invention not only has good compatibility with the polyester, but also the mechanical properties of the polyester composite material containing this flame retardant are not significantly damaged, and it can still maintain good flame retardant properties after undergoing high and low temperature cyclic aging.

[0016] The present invention also provides a method for preparing the high and low temperature resistant flame retardant for the above polyester, which includes the following steps:

[0017] Mix the phenylphosphazene compound, the hydroxypyrazine compound, the catalyst, and the organic solvent evenly, heat up to the reflux state and keep it at a constant temperature, carry out the reaction under stirring conditions, rotary evaporate and concentrate, pour the concentrate into ice water, separate the oil layer, adjust the pH to neutral, separate the oil layer again, dry with a desiccant, filter, and separate by column chromatography.

[0018] The organic solvent is selected from one or a combination of two of toluene, xylene, diphenyl ether, and dioxane; the reflux temperature is 100 - 140 °C, the reaction time is 3 - 5 h, the pH adjustment is carried out by adding an alkali or an alkali solution, the alkali is not particularly limited and can be commonly used in the art, including but not limited to one or a combination of two or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, and potassium hydroxide, and the alkali solution is also not particularly limited and can be commonly used in the art, including but not limited to one or a combination of two or more of sodium carbonate aqueous solution, sodium bicarbonate aqueous solution, sodium hydroxide aqueous solution, and potassium hydroxide aqueous solution; the eluent for the column chromatography separation is petroleum ether: ethyl acetate 80 - 60:20.

[0019] A flame retardant polyester composite material includes the following raw materials in parts by weight: 100 parts of polyester, 15 - 25 parts of flame retardant, and 3 - 5 parts of lubricant.

[0020] The polyester is selected from one or a combination of two of PET and PBT.

[0021] The intrinsic viscosity of the polyester is 0.6 - 0.85 dl / g.

[0022] The lubricant is not particularly limited and can be commonly used in the art, including but not limited to one or a combination of two or more of zinc stearate, ethylene bisstearamide, high melting point paraffin, or butyl stearate.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The present invention uses phenylphosphonitrile compounds and hydroxypyrazine compounds as raw materials, and undergoes an alcoholysis reaction of nitrile groups to form esters under the catalysis of concentrated sulfuric acid. The product has good compatibility with PET, can efficiently flame retardant without causing excessive damage to the mechanical properties of PET, and the PET composite material containing this flame retardant has excellent high and low temperature cycle aging resistance.

[0025] The flame retardant synthesized by the present invention has good thermal stability, does not release harmful gases during the flame retardant process, and can achieve good flame retardant effects with a small amount added.

[0026] The preparation method of the present invention is simple and suitable for large-scale production. Detailed implementation mode

[0027] The following further illustrates the present invention with specific examples, but is not limited to the content in the specification. Unless otherwise specified, the "parts" mentioned in the embodiments of the present invention are all parts by weight. The reagents used are all commercially available reagents in the art.

[0028] (Diphenylphosphoryl)acetonitrile was purchased from American Custom Chemicals Corporation;

[0029] (6-Methyl-2,3,5-pyrazinetriyl)trimethanol was purchased from Puyang Tianyuan Biotechnology Co., Ltd.;

[0030] PET was purchased from Sinopec Yizheng Chemical Fiber Co., Ltd., and the intrinsic viscosity was 0.82 dl / g.

[0031] Preparation of flame retardant

[0032] Example 1

[0033] Mix 3.78 mol of (diphenylphosphoryl)acetonitrile, 1 mol of (6-methyl-2,3,5-pyrazinetriyl)trimethanol, 458.4 g of 93 wt% concentrated sulfuric acid, and 1600 g of toluene evenly, heat up to the reflux state and keep it constant temperature, carry out the reaction for 5 h under stirring conditions, rotary evaporate and concentrate, pour the concentrate into 5000 g of ice water, separate the oil layer, dropwise add saturated sodium bicarbonate aqueous solution to the oil phase until the pH is 7, separate the oil layer again, add anhydrous sodium sulfate for drying, filter, and separate the liquid through a silica gel column. The eluent is petroleum ether:ethyl acetate 80:20. The chemical reaction that occurs is shown as follows:

[0034]

[0035] 1 HNMR(CDCl 3 ): 2.35(s, 3H,), 5.34(s, 6H,), 3.66(d, 6H,), 6.96 - 8.12(m, 30H,).

[0036] Example 2

[0037] The rest is the same as in Example 1, except that the amount of (diphenylphosphoryl)acetonitrile is 3.42 mol.

[0038] Example 3

[0039] The rest is the same as in Example 1, except that the amount of 93 wt% concentrated sulfuric acid is 395.2 g.

[0040] Example 4

[0041] The rest is the same as in Example 1, except that the amount of (diphenylphosphoryl)acetonitrile is 3 mol.

[0042] Example 5

[0043] The rest is the same as in Example 1, except that the amount of (diphenylphosphoryl)acetonitrile is 3.9 mol.

[0044] Example 6

[0045] The rest is the same as in Example 1, except that 1.5 mol of 2,3-pyrazinedimethanol is used to replace 1 mol of (6-methyl-2,3,5-pyrazinetriyl)trimethanol. The chemical reaction that occurs is as follows:

[0046]

[0047] 1 HNMR(CDCl 3 ): 8.45(s, 2H,), 5.32(s, 4H,), 3.60(d, 4H,), 7.31 - 7.95(m, 20H,).

[0048] Preparation of flame-retardant PET composite material

[0049] Application Example 1

[0050] Put 100 parts of PET, 25 parts of the flame retardant prepared in Example 1, and 3 parts of zinc stearate into a mixer, mix evenly, dry in vacuum at 80 °C for 5 h, and use an injection molding machine to perform injection molding at 245 °C.

[0051] Application Examples 2 - 6

[0052] The rest is the same as in Application Example 1, except that the flame retardants correspond to those prepared in Examples 2 - 6 respectively.

[0053] Application Example 7

[0054] The rest is the same as in Application Example 1, except that the amount of the flame retardant in Preparation Example 1 is 15 parts.

[0055] Comparative Application Example 1

[0056] The rest is the same as Application Example 1, except that 15 parts of TTPS, 6.25 parts of MCA, and 3.75 parts of DOPO in Patent CN201410508022.9 are used to replace 25 parts of the flame retardant prepared in Example 1.

[0057] The flame retardants prepared in the above Examples 1-6 were subjected to the following tests, and the results are shown in Table 1:

[0058] Thermogravimetric analysis: The test was carried out using a TG 209F1 thermogravimetric analyzer from Netzsch, Germany. The test conditions were: nitrogen atmosphere, heating rate of 10 °C / min, temperature range of 50 - 800 °C.

[0059] Table 1

[0060]

[0061]

[0062] The composites prepared in the above Application Examples 1-7 were subjected to the following property tests:

[0063] Tensile properties: The test was carried out with reference to the test method for tensile properties of plastic films in Standard GB / T 13022-1991, and the tensile strength was recorded.

[0064] Flame retardancy: The test was carried out with reference to the vertical burning method for plastics in GB / T 2408-2008 (equivalent to the UL-94 standard), and the specimen size was 125 mm × 13 mm × 3.0 mm.

[0065] High and low temperature cycle aging: The specimen was first subjected to 1000 cold and hot cycles at -40 °C - 85 °C, and then, with reference to the test method for tensile properties of plastic films in Standard GB / T 13022-1991, the tensile property test and the flame retardancy test were carried out again, and the tensile strength retention rate was calculated.

[0066] Table 2

[0067] Project Tensile strength MPa Retention rate of tensile strength after aging % UL UL test after aging Application Example 1 57.6 98.1 V0 V0 Application Example 2 57.4 98.1 V0 V0 Application Example 3 56.2 97.7 V0 V0 Application Example 4 55.9 97.0 V1 V2 Application Example 5 57.5 98.1 V0 V0 Application Example 6 55.7 95.2 V0 V1 Application Example 7 58.8 98.5 V1 V1 Comparative Application Example 1 57.9 91.1 V0 V2

[0068] The flame retardant prepared in the present invention has good compatibility with PET, can achieve high-efficiency flame retardancy without causing too much damage to the mechanical properties of PET, and the PET composite material containing this flame retardant has excellent high and low temperature cycle aging resistance.

[0069] The flame retardant synthesized in the present invention has good thermal stability, does not release harmful gases during the flame retardant process, and can achieve good flame retardant effects with the addition of a small amount.

[0070] The preparation method of the present invention is simple, suitable for large-scale production, and can be used to prepare packaging products such as beverage bottles or hot filling bottles that are used under high and low temperature change conditions.

[0071] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification without departing from the present invention shall be included within the scope of the technical solution of the present invention.

Claims

1. A high and low temperature resistant flame retardant for polyester, characterized in that, the high and low temperature resistant flame retardant for polyester comprises the following raw materials: phenylphosphonitrile compound, hydroxypyrazine compound, concentrated sulfuric acid; the molar ratio of nitrile groups to hydroxyl groups in the phenylphosphonitrile compound and hydroxypyrazine compound is 1.14 - 1.26:1; the phenylphosphonitrile compound is (diphenylphosphoryl)acetonitrile; the hydroxypyrazine compound is selected from one or a combination of two of 2,3 - pyrazinedimethanol and (6 - methyl - 2,3,5 - pyrazinetriyl)trimethanol; the polyester is PET; the preparation method of the high and low temperature resistant flame retardant for polyester comprises the following steps: mixing the phenylphosphonitrile compound, hydroxypyrazine compound, concentrated sulfuric acid and organic solvent evenly, heating to the reflux state and keeping constant temperature, carrying out the reaction under stirring conditions, rotary evaporation and concentration, pouring the concentrate into ice water, separating the oil layer, adjusting the pH to neutral, separating the oil layer again, drying with a desiccant, filtering and column chromatography separation.

2. The high and low temperature resistant flame retardant for polyester according to claim 1, characterized in that, The molar ratio of H 2 SO 4 in the concentrated sulfuric acid to the hydroxyl group in the hydroxypyrazine compound is 1.25 - 1.45:1, and the concentration of the concentrated sulfuric acid is 93 - 98 wt%.

3. The high and low temperature resistant flame retardant for polyester according to claim 1, characterized in that, the organic solvent is selected from one or a combination of two of toluene, xylene and dioxane; the reflux temperature is 100 - 140 °C, and the eluent for column chromatography separation is petroleum ether:ethyl acetate, and the ratio is 80 - 60:

20.

4. A flame retardant polyester composite material, characterized in that, it comprises the following raw materials in parts by weight: 100 parts of polyester, 15 - 25 parts of the high and low temperature resistant flame retardant for polyester according to any one of claims 1 - 3, 3 - 5 parts of lubricant, and the polyester is PET.

5. The flame retardant polyester composite material according to claim 4, characterized in that, the intrinsic viscosity of the polyester is 0.6 - 0.85 dl / g.

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