A flame-retardant polyamide 66 resin and its preparation method

Abstract

This invention provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight: 85-98 parts of hexamethylenediamine and adipic acid, 2-8 parts of a phosphorus-based flame retardant, 1-4 parts of a nitrogen-based flame retardant, 2-5 parts of a silicon-based flame retardant, and 0.1-2 parts of a third monomer; the molar ratio of hexamethylenediamine to adipic acid is (1-1.05):1. This invention, through the design of the specific composition of the flame-retardant polyamide 66 resin and the synergistic effect of phosphorus-based, nitrogen-based, and silicon-based flame retardants, prepares a flame-retardant polyamide 66 resin with both high flame retardancy and good mechanical properties. Furthermore, the preparation method of the flame-retardant polyamide 66 resin provided by this invention is simple to operate, expanding the application market of the flame-retardant polyamide 66 resin.

Description

Technical Field

[0001] This invention belongs to the technical field of flame-retardant polyamide materials, specifically relating to a flame-retardant polyamide 66 resin and its preparation method. Background Technology

[0002] Polyamide 66 has good mechanical properties, wear resistance, and chemical corrosion resistance, and is widely used in engineering plastics and chemical fibers. However, the limiting oxygen index (LOI) of polyamide 66 is 22%-24%, which means it is not a flame retardant material. Moreover, it exhibits severe dripping during combustion, which can easily spread the fire. Its flammability limits its application range.

[0003] Flame-retardant polyamide 66 is typically prepared by adding flame retardants to a polyamide system. Based on the addition mechanism, flame retardants can be classified into reactive and additive flame retardants. Based on their chemical composition, they can be classified into halogen-based, phosphorus-based, silicon-based, inorganic, and nano-additive flame retardants. Furthermore, different flame retardants can be synergistically added to the system to achieve better flame-retardant effects. Common synergistic flame-retardant systems include antimony-halogen, phosphorus-halogen, and phosphorus-nitrogen systems. The flame-retardant mechanisms can be mainly categorized as condensed phase flame retardancy, free radical capture, cooling, non-flammable gases, and synergistic effects.

[0004] Halogenated flame retardants, including bromine-based and chlorine-based flame retardants, are among the most produced organic flame retardants in the world, with a wide variety of types. Bromine-based flame retardants are particularly popular due to their excellent performance and moderate price. While halogenated flame retardants effectively reduce the spread of fire, the smoke and toxic corrosive gases produced during combustion can cause secondary damage. Furthermore, once halogenated compounds enter the atmosphere, they are difficult to remove, persist for a long time, and deplete the ozone layer.

[0005] Phosphorus-based flame retardants decompose during combustion to form phosphoric acid, creating a non-flammable liquid film. Simultaneously, the phosphoric acid further dehydrates to form metaphosphoric acid, which then polymerizes to form polymetaphosphoric acid. In this process, not only does the resulting phosphoric acid liquid film provide a covering effect, but the polymetaphosphoric acid, being a strong acid and a powerful dehydrating agent, dehydrates and carbonizes the polymer, altering its combustion process and forming a carbon film on its surface to isolate it from air, thus enhancing its flame-retardant effect. Generally, phosphorus-based flame retardants are most effective on oxygen-containing polymers and are primarily used in polymers containing hydroxyl groups, such as cellulose, polyurethane, and polyester. For non-oxygen-containing hydrocarbon polymers, the effect of phosphorus-based flame retardants is relatively small.

[0006] Silicon-based flame retardants are important halogen-free and environmentally friendly flame retardants with good thermal stability, water resistance, and low toxicity. Silicon-based flame retardants can be divided into organosilicon and inorganic silicon types. Organosilicon flame retardants mainly include silicone oils, silicone resins, and silicone rubbers, while inorganic silicon flame retardants mainly include silicates and aluminum silicates. Silicon-based flame retardants impart excellent flame retardant and smoke-suppressing properties to polymers while also improving the polymer's processing performance and mechanical strength.

[0007] The phosphorus-nitrogen system exhibits a synergistic flame-retardant effect, forming an intumescent char layer on the surface of objects at high temperatures, thus acting as a heat-insulating and oxygen-barrier protective layer. Nitrogen compounds act as foaming agents and char-reinforcing agents, while phosphides provide an acid source, reacting with the resin to promote char formation. Furthermore, nitrides also provide a gas source, causing the system to expand and foam, further promoting the formation of the char layer and creating a porous, foamed char layer. Additionally, silicon-based flame retardants promote char formation during combustion, resulting in a dense silicon-carbon layer.

[0008] CN106987117A discloses a technical solution for preparing flame-retardant polyamide by compounding phosphorus and nitrogen-based flame retardants, which increases the glow wire ignition temperature of the melamine cyanurate system to above 750℃, and significantly improves the flame-retardant effect. However, it uses a melt blending method to add flame retardants, raising concerns about the uniformity of the flame retardants, and requires secondary processing, making the operation complex.

[0009] In existing technologies, the addition of flame retardants can lead to a decrease in the mechanical properties of polyamide materials. Therefore, how to provide a polyamide material that possesses both high flame retardancy and good mechanical properties has become an urgent technical problem to be solved. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the present invention aims to provide a flame-retardant polyamide 66 resin and its preparation method. This invention designs the specific composition of the flame-retardant polyamide 66 resin and further utilizes the synergistic effect of phosphorus-based, nitrogen-based, and silicon-based flame retardants to prepare a flame-retardant polyamide 66 resin that possesses both high flame retardancy and good mechanical properties. Simultaneously, the preparation method of the flame-retardant polyamide 66 resin provided by this invention is simple to operate, expanding the application market for flame-retardant polyamide 66 resin.

[0011] To achieve this objective, the present invention adopts the following technical solution:

[0012] In a first aspect, the present invention provides a flame-retardant polyamide 66 resin, wherein the raw materials for preparing the flame-retardant polyamide 66 resin comprise the following components in parts by weight:

[0013] The mixture contains 85-98 parts of hexamethylenediamine and adipic acid, 2-8 parts of phosphorus-based flame retardant, 1-4 parts of nitrogen-based flame retardant, 2-5 parts of silicon-based flame retardant, and 0.1-2 parts of a third monomer.

[0014] The molar ratio of hexamethylenediamine to adipic acid is (1-1.05):1.

[0015] This invention designs the specific composition of flame-retardant polyamide 66 resin and further improves the flame retardancy of polyamide 66 resin through the synergistic effect of phosphorus-based flame retardants, nitrogen-based flame retardants, and silicon-based flame retardants, achieving a flame retardancy rating of V-0. It also improves the dripping problem of polyamide 66 resin while retaining the original good mechanical properties of polyamide 66 resin, thus preparing a flame-retardant polyamide 66 resin with both high flame retardancy and good mechanical properties.

[0016] In this invention, the overall performance of flame-retardant polyamide 66 resin is optimized through the synergistic effect of phosphorus-based flame retardants, nitrogen-based flame retardants and silicon-based flame retardants in a specific range of dosages.

[0017] In this invention, the mechanical properties of flame-retardant polyamide 66 resin are improved by using a third monomer and controlling its amount within a specific range. If the amount of the third monomer is too small, it will not improve the material properties; if the amount of the third monomer is too large, it will easily form oligomers that act as plasticizers, reducing the mechanical strength of the material.

[0018] In this invention, the sum of the weight parts of hexamethylenediamine and adipic acid in the raw materials for preparing the flame-retardant polyamide 66 resin can be 85 parts, 86 parts, 87 parts, 88 parts, 89 parts, 90 parts, 91 parts, 92 parts, 93 parts, 94 parts, 95 parts, 96 parts, 97 parts, or 98 parts, etc.

[0019] In the raw materials for preparing the flame-retardant polyamide 66 resin, the weight parts of the phosphorus-based flame retardant can be 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, or 8 parts, etc.

[0020] In the raw materials for preparing the flame-retardant polyamide 66 resin, the weight parts of the nitrogen-based flame retardant can be 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, or 4 parts, etc.

[0021] In the raw materials for preparing the flame-retardant polyamide 66 resin, the weight parts of the silicone flame retardant can be 2 parts, 2.2 parts, 2.5 parts, 2.7 parts, 3 parts, 3.3 parts, 3.5 parts, 3.8 parts, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, or 5 parts, etc.

[0022] In the raw materials for preparing the flame-retardant polyamide 66 resin, the weight parts of the third monomer can be 0.1 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, or 2 parts, etc.

[0023] The molar ratio of hexamethylenediamine to adipic acid is (1 to 1.05):1, for example, it can be 1:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1 or 1.05:1, etc.

[0024] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0025] As a preferred embodiment of the present invention, the phosphorus-based flame retardant is selected from 3-hydroxyphenylphosphonopropionic acid and / or aluminum aminotrimethylenephosphonate (NYP3).

[0026] As a preferred embodiment of the present invention, the nitrogen-based flame retardant is selected from melamine cyanurate (MCA) and / or melamine, preferably melamine cyanurate (MCA).

[0027] As a preferred embodiment of the present invention, the silicon-based flame retardant is selected from silicone resin micro powder and / or silicone oil, preferably silicone resin micro powder.

[0028] In this invention, the flame retardancy of polyamide 66 resin is improved through the synergistic effect of specific phosphorus-based flame retardants, nitrogen-based flame retardants, and silicon-based flame retardants.

[0029] This invention further optimizes the overall performance of polyamide 66 resin by using 3-hydroxyphenylphosphonopropionic acid and / or aluminum aminotrimethylenephosphonate, melamine cyanurate, and silicone resin micro powder, thereby improving the flame retardant properties and mitigating the dripping problem of polyamide 66 resin.

[0030] As a preferred embodiment of the present invention, the third monomer is selected from any one or a combination of at least two of autolactam, sebacic acid, or dodecanoic acid.

[0031] This invention further optimizes the overall performance of polyamide 66 resin by using a specific third monomer.

[0032] As a preferred technical solution of the present invention, the raw materials for preparing the flame-retardant polyamide 66 resin further include 0.1-1 parts by weight of antioxidant, for example, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight or 1 part by weight.

[0033] Preferably, the antioxidant is selected from any one or a combination of at least two of antioxidants H10, AO3349, H161, H3373, H1010, H1098 or dilauryl thiodipropionate.

[0034] Preferably, the raw materials for preparing the flame-retardant polyamide 66 salt also include 0.2-1 parts by weight of heat stabilizer, for example, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight or 1 part by weight.

[0035] Preferably, the heat stabilizer is selected from any one or a combination of at least two of copper acetate-potassium iodide, copper acetate-cuprous iodide-potassium iodide, copper acetate-potassium bromide, or copper acetate-cuprous bromide-potassium bromide.

[0036] It should be noted that in this invention, copper acetate-potassium iodide represents a combination of copper acetate and potassium iodide. Similarly, copper acetate-cuprous iodide-potassium iodide represents a combination of copper acetate, cuprous iodide and potassium iodide, copper acetate-potassium bromide represents a combination of copper acetate and potassium bromide, and copper acetate-cuprous bromide-potassium bromide represents a combination of copper acetate, cuprous bromide and potassium bromide.

[0037] Preferably, the raw materials for preparing the flame-retardant polyamide 66 salt further include 0.01-0.1 parts by weight of catalyst, for example, 0.01 parts by weight, 0.05 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, or 1 part by weight.

[0038] Preferably, the catalyst is selected from any one or a combination of at least two of phosphoric acid, phosphorous acid, hypophosphite organic compounds or hypophosphite.

[0039] It should be noted that the present invention does not impose any special restrictions on the specific selection of hypophosphite organic compounds and hypophosphites. Commonly used hypophosphite organic compounds and hypophosphites in the art are applicable, including but not limited to sodium hypophosphite.

[0040] In a second aspect, the present invention provides a method for preparing flame-retardant polyamide 66 resin as described in the first aspect, the method comprising the following steps:

[0041] (1) Hexamethylenediamine and adipic acid undergo a salt formation reaction, and the pH is adjusted to obtain a polyamide 66 salt solution;

[0042] (2) Mix the polyamide 66 salt solution with other raw materials for preparing flame retardant polyamide 66 and react them to obtain the flame retardant polyamide 66 resin.

[0043] As a preferred embodiment of the present invention, the temperature of the salt-forming reaction is 50℃~80℃ (for example, it can be 50℃, 52℃, 55℃, 57℃, 60℃, 63℃, 66℃, 68℃, 70℃, 72℃, 75℃, 77℃ or 80℃), and the time is 20min~30min (for example, it can be 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min or 30min, etc.).

[0044] Preferably, the salt formation reaction is carried out in a protective atmosphere and in the presence of a solvent, the solvent including water.

[0045] In this invention, the protective gas atmosphere can be an argon atmosphere or a nitrogen atmosphere.

[0046] Preferably, after pH adjustment, the pH of the polyamide 66 salt solution is 7.00 to 7.80, for example, it can be 7.00, 7.10, 7.20, 7.30, 7.40, 7.50, 7.60, 7.70 or 7.80, etc.

[0047] In this invention, adipic acid or hexamethylenediamine can be added to the reaction system as described in step (1) to adjust the pH of the reaction system.

[0048] Preferably, the polyamide 66 salt solution has a mass percentage content of 40% to 60%, for example, it can be 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, or 60%.

[0049] As a preferred technical solution of the present invention, the mixing temperature in step (2) is 50℃~80℃, for example, it can be 50℃, 52℃, 55℃, 57℃, 60℃, 63℃, 66℃, 68℃, 70℃, 72℃, 75℃, 77℃ or 80℃.

[0050] Preferably, the reaction in step (2) includes the following steps: heating the reaction system until the pressure of the reaction system reaches 0.15 MPa to 0.20 MPa (e.g., 0.15 MPa, 0.155 MPa, 0.16 MPa, 0.165 MPa, 0.17 MPa, 0.175 MPa, 0.18 MPa, 0.185 MPa, 0.19 MPa, 0.195 MPa, or 0.20 MPa, etc.), and concentrating the mass concentration of the polyamide 66 salt solution to 60% to 70% (e.g., 60%, 61%, 62%, 63%, 64%, 65%, 66%). 67%, 68%, 69%, or 70%, etc.); continue heating until the reaction system pressure is 0.8 MPa to 1.3 MPa (e.g., 0.8 MPa, 0.85 MPa, 0.9 MPa, 0.95 MPa, 1 MPa, 1.05 MPa, 1.1 MPa, 1.15 MPa, 1.2 MPa, 1.25 MPa, or 1.3 MPa, etc.), concentrating the polyamide 66 salt solution to 70% to 90% (e.g., 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, or 9 ...5 MPa, 1 MPa, 1.05 MPa, 1.15 MPa, 1.15 MPa, 1.2 MPa, 1.25 MPa, or 1.3 MPa, etc.); After concentrating the polyamide 66 salt solution to 92%–97% (e.g., 92%, 93%, 94%, 95%, 96%, or 97%) at a pressure of 1.6 MPa–2.0 MPa (e.g., 1.6 MPa, 1.65 MPa, 1.7 MPa, 1.75 MPa, 1.8 MPa, 1.85 MPa, 1.95 MPa, or 2.0 MPa), the pressure is increased and the pressure is decreased by discharging water. The pressure of the reaction system is then reduced to atmospheric pressure at 260℃–290℃ (e.g., 260℃, 265℃, 270℃, 275℃, 280℃, or 285℃). The polymerization reaction is carried out for 5 min to 30 min (e.g., 5 min, 7 min, 10 min, 12 min, 15 min, 18 min, 20 min, 23 min, 25 min, 27 min, or 30 min) under conditions of 290℃ or pressure of -0.01 MPa to -0.1 MPa (e.g., -0.01 MPa, -0.02 MPa, -0.03 MPa, -0.04 MPa, -0.05 MPa, -0.06 MPa, -0.07 MPa, -0.08 MPa, -0.09 MPa, or -0.1 MPa).

[0051] As a preferred embodiment of the present invention, the preparation method of the flame-retardant polyamide 66 resin specifically includes the following steps:

[0052] (1) In a protective atmosphere, hexamethylenediamine, adipic acid and water are mixed and a salt-forming reaction is carried out at 50℃~80℃ for 20min~30min. The pH is adjusted to 7.00~7.80 to obtain a polyamide 66 salt solution with a mass concentration of 40%~60%.

[0053] (2) At 50℃~80℃, the polyamide 66 salt solution and other raw materials for preparing flame-retardant polyamide 66 are mixed and heated. When the pressure of the reaction system reaches 0.15MPa~0.20MPa, the mass concentration of the polyamide 66 salt solution is concentrated to 60%~70%. The temperature is further increased to the pressure of the reaction system to 0.8MPa~1.3MPa, and the mass concentration of the polyamide 66 salt solution is concentrated to 70%~90%. The temperature is further increased to the pressure of the reaction system to 1.6MPa~2.0MPa, and the mass concentration of the polyamide 66 salt solution is concentrated to 92%~97%. Then, the temperature is increased and the pressure is decreased to drain water. The pressure of the reaction system is reduced to normal pressure. The polymerization reaction is carried out at 260℃~290℃ and a pressure of -0.01MPa~-0.1MPa for 5min~30min to obtain the flame-retardant polyamide 66 resin.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] This invention designs the specific composition of flame-retardant polyamide 66 resin and further utilizes the synergistic effect of phosphorus-based flame retardants, nitrogen-based flame retardants, and silicon-based flame retardants to prepare flame-retardant polyamide 66 resin with both high flame retardancy and good mechanical properties. At the same time, the preparation method of flame-retardant polyamide 66 resin provided by this invention is simple to operate, expanding the application market of flame-retardant polyamide 66 resin. Detailed Implementation

[0056] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0057] The sources of some components in the examples and comparative examples are as follows:

[0058] Silicone resin micro powder: Ningbo Jinlei Nanomaterials Technology Co., Ltd., JL-SiO2-GY300;

[0059] Silicone oil: Momentive Advanced Materials Group, TSF4708;

[0060] Antioxidant H10: Shanghai Newno Chemical Technology Co., Ltd., BRUGGOLEN H10.

[0061] Example 1

[0062] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0063] The mixture contains 87 parts of hexamethylenediamine and adipic acid, 6 parts of 3-hydroxyphenylphosphopropionic acid, 2 parts of melamine cyanurate, 4 parts of silicone resin micro powder, 0.15 parts of antioxidant H10, 0.6 parts of caprolactam, 0.2 parts of potassium iodide, 0.02 parts of copper acetate, and 0.03 parts of sodium hypophosphite.

[0064] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0065] The preparation method of the above flame-retardant polyamide 66 resin is as follows:

[0066] (1) Add hexamethylenediamine and adipic acid to a salt-forming kettle, add pure water, and carry out salt formation at 60°C under a nitrogen atmosphere. After salt formation, adjust the pH value to 7.30 to obtain a polyamide 66 salt solution with a mass concentration of 50%.

[0067] (2) The polyamide 66 salt solution obtained in step (1) is added to the polymerization reactor. Then, 3-hydroxyphenylphosphopropionic acid, melamine cyanurate, silicone resin powder, antioxidant H10, caprolactam, potassium iodide, copper acetate, and sodium hypophosphite are added to the polymerization reactor in sequence for nitrogen purging. After nitrogen purging, the polymerization reactor is heated. When the pressure inside the reactor reaches 0.20 MPa, the salt solution is drained and concentrated to concentrate the mass concentration of the polyamide 66 salt solution to 65%. The temperature is then increased until the pressure inside the polymerization reactor reaches 1 MPa. The pressure inside the polymerization reactor was increased to 1.1 MPa, and the solution was concentrated by water drainage to 80% concentration. The temperature was then increased further until the pressure reached 1.8 MPa, at which point the solution was concentrated by water drainage to 95% concentration. The pressure was then decreased and the solution was drained. When the temperature inside the reactor reached 280°C and the pressure dropped to atmospheric pressure, negative pressure polymerization began. The system was pumped to -0.05 MPa and the reaction continued for 10 minutes. The solution was then discharged through the discharge port to obtain the flame-retardant polyamide 66 resin.

[0068] Example 2

[0069] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0070] The mixture contains 92 parts of hexamethylenediamine and adipic acid, 3 parts of 3-hydroxyphenylphosphopropionic acid, 1 part of melamine cyanurate, 2 parts of silicone resin micro powder, 0.45 parts of antioxidant H10, 1 part of sebacic acid, 0.4 parts of potassium iodide, 0.05 parts of copper acetate, and 0.1 parts of sodium hypophosphite.

[0071] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0072] The preparation method of the above flame-retardant polyamide 66 resin is the same as that in Example 1.

[0073] Example 3

[0074] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0075] The mixture contains 85 parts of hexamethylenediamine and adipic acid, 6 parts of 3-hydroxyphenylphosphopropionic acid, 4 parts of melamine cyanurate, 4 parts of silicone resin micro powder, 0.15 parts of antioxidant H10, 0.6 parts of dodecanoic acid, 0.2 parts of potassium iodide, 0.02 parts of copper acetate, and 0.03 parts of sodium hypophosphite.

[0076] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0077] The preparation method of the above flame-retardant polyamide 66 resin is the same as that in Example 1.

[0078] Example 4

[0079] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method, which differs from Example 1 only in that:

[0080] Replace melamine cyanurate with an equal part by weight of melamine;

[0081] Other conditions are the same as in Example 1.

[0082] Example 5

[0083] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method, which differs from Example 1 only in that:

[0084] Replace the silicone resin powder with an equal amount of silicone oil by weight;

[0085] Other conditions are the same as in Example 1.

[0086] Example 6

[0087] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method, which differs from Example 1 only in that:

[0088] Replace 3-hydroxyphenylphosphonopropionic acid with an equal weight of aluminum aminotrimethylene phosphate;

[0089] Other conditions are the same as in Example 1.

[0090] Example 7

[0091] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method, which differs from Example 1 only in that:

[0092] Step (1): After salt formation, adjust the pH value to 7.10;

[0093] Other conditions are the same as in Example 1.

[0094] Example 8

[0095] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method, which differs from Example 1 only in that:

[0096] Step (1): After salt formation, adjust the pH value to 7.60;

[0097] Other conditions are the same as in Example 1.

[0098] Example 9

[0099] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method, which differs from Example 1 only in that:

[0100] Step (2): After pumping the system to -0.05 MPa, continue the reaction for 20 min;

[0101] Other conditions are the same as in Example 1.

[0102] Example 10

[0103] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0104] The composition includes 87.5 parts of hexamethylenediamine and adipic acid, 6 parts of 3-hydroxyphenylphosphopropionic acid, 2 parts of melamine cyanurate, 4 parts of silicone resin micro powder, 0.15 parts of antioxidant H10, 0.1 parts of caprolactam, 0.2 parts of potassium iodide, 0.02 parts of copper acetate, and 0.03 parts of sodium hypophosphite.

[0105] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0106] The preparation method of the above flame-retardant polyamide 66 resin is the same as that in Example 1.

[0107] Example 11

[0108] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0109] The composition includes 85.6 parts of hexamethylenediamine and adipic acid, 6 parts of 3-hydroxyphenylphosphopropionic acid, 2 parts of melamine cyanurate, 4 parts of silicone resin micro powder, 0.15 parts of antioxidant H10, 2 parts of caprolactam, 0.2 parts of potassium iodide, 0.02 parts of copper acetate, and 0.03 parts of sodium hypophosphite.

[0110] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0111] The preparation method of the above flame-retardant polyamide 66 resin is the same as that in Example 1.

[0112] Example 12

[0113] This embodiment provides a flame-retardant polyamide 66 resin and its preparation method, which differs from Example 1 only in that:

[0114] Replace caprolactam with an equal weight of sebacic acid;

[0115] Other conditions are the same as in Example 1.

[0116] Comparative Example 1

[0117] This comparative example provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0118] The composition includes 87.6 parts of hexamethylenediamine and adipic acid, 6 parts of 3-hydroxyphenylphosphopropionic acid, 2 parts of melamine cyanurate, 4 parts of silicone resin micro powder, 0.15 parts of antioxidant H10, 0.2 parts of potassium iodide, 0.02 parts of copper acetate, and 0.03 parts of sodium hypophosphite.

[0119] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0120] The preparation method of the above flame-retardant polyamide 66 resin is the same as that in Example 1.

[0121] Comparative Example 2

[0122] This comparative example provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0123] The composition includes 85.1 parts of hexamethylenediamine and adipic acid, 6 parts of 3-hydroxyphenylphosphopropionic acid, 2 parts of melamine cyanurate, 4 parts of silicone resin micro powder, 0.15 parts of antioxidant H10, 2.5 parts of caprolactam, 0.2 parts of potassium iodide, 0.02 parts of copper acetate, and 0.03 parts of sodium hypophosphite.

[0124] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0125] The preparation method of the above flame-retardant polyamide 66 resin is the same as that in Example 1.

[0126] Comparative Example 3

[0127] This comparative example provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0128] The mixture contains 98 parts of hexamethylenediamine and adipic acid, 0.15 parts of antioxidant H10, 2.5 parts of caprolactam, 0.2 parts of potassium iodide, 0.02 parts of copper acetate, and 0.03 parts of sodium hypophosphite.

[0129] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0130] The preparation method of the above flame-retardant polyamide 66 resin is as follows:

[0131] (1) Add hexamethylenediamine and adipic acid to a salt-forming kettle, add pure water, and carry out salt formation at 60°C under a nitrogen atmosphere. After salt formation, adjust the pH value to 7.30 to obtain a polyamide 66 salt solution with a mass concentration of 50%.

[0132] (2) The polyamide 66 salt solution obtained in step (1) is put into the polymerization reactor and nitrogen is purged. After the nitrogen purging is completed, the polymerization reactor is heated. When the pressure inside the reactor reaches 0.20 MPa, the salt solution is drained and concentrated to a mass concentration of 65% for the polyamide 66 salt solution. The temperature is continued to rise until the pressure inside the polymerization reactor reaches 1.1 MPa. The solution is then drained and concentrated to a mass concentration of 80% for the polyamide 66 salt solution. The temperature is continued to rise until the pressure inside the polymerization reactor reaches 1.8 MPa. The solution is then drained and concentrated to a mass concentration of 95% for the polyamide 66 salt solution. After that, the temperature is raised and the pressure is lowered and the water is drained. When the temperature inside the reactor reaches 280°C and the pressure inside the polymerization reactor drops to atmospheric pressure, negative pressure polymerization is started. The system is pumped to -0.05 MPa and the reaction continues for 10 minutes. After that, the material is discharged through the discharge port to obtain the flame-retardant polyamide 66 resin.

[0133] Comparative Example 4

[0134] This comparative example provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0135] The mixture contains 87 parts of hexamethylenediamine and adipic acid, 4 parts of melamine cyanurate, 8 parts of silicone resin powder, 0.15 parts of antioxidant H10, 0.6 parts of caprolactam, 0.2 parts of potassium iodide, 0.02 parts of copper acetate, and 0.03 parts of sodium hypophosphite.

[0136] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0137] The preparation method of the above flame-retardant polyamide 66 resin is the same as that in Example 1.

[0138] Comparative Example 5

[0139] This comparative example provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0140] The mixture contains 87 parts of hexamethylenediamine and adipic acid, 9 parts of 3-hydroxyphenylphosphopropionic acid, 3 parts of melamine cyanurate, 0.15 parts of antioxidant H10, 0.6 parts of caprolactam, 0.2 parts of potassium iodide, 0.02 parts of copper acetate, and 0.03 parts of sodium hypophosphite.

[0141] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0142] The preparation method of the above flame-retardant polyamide 66 resin is the same as that in Example 1.

[0143] Comparative Example 6

[0144] This comparative example provides a flame-retardant polyamide 66 resin and its preparation method. The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight:

[0145] The mixture contains 87 parts of hexamethylenediamine and adipic acid, 7.2 parts of 3-hydroxyphenylphosphopropionic acid, 0.15 parts of antioxidant H10, 0.6 parts of caprolactam, 0.2 parts of potassium iodide, 0.02 parts of copper acetate, and 0.03 parts of sodium hypophosphite.

[0146] The molar ratio of hexamethylenediamine to adipic acid is 1:1.

[0147] The preparation method of the above flame-retardant polyamide 66 resin is the same as that in Example 1.

[0148] The performance of the flame-retardant polyamide 66 resins provided in the above embodiments and comparative examples was tested, and the specific test methods are as follows:

[0149] (1) Relative viscosity test: The Ubbelohde viscometer concentrated sulfuric acid method was used for the test. The specific steps are as follows: Weigh 0.30±0.0002g of dried flame retardant polyamide 66 resin sample, add 30mL of concentrated sulfuric acid (mass concentration of 96%), dissolve it at 60℃ to obtain sample solution, weigh and record the flow time t0 of concentrated sulfuric acid and the flow time t of sample solution in a constant temperature water bath at 25℃;

[0150] Relative viscosity η r = t / t0.

[0151] (2) Melting point: Under the conditions of ambient temperature 23±2℃ and humidity 50±5% RH, the sample was tested using a differential scanning calorimeter (DSC) according to the test standard "ISO 11357-3:2011 Differential scanning calorimetry (DSC) for plastics - Part 3: melting and solidification temperatures and enthalpy".

[0152] (3) Tensile strength: determined according to ISO 527-2 method, with a tensile speed of 50 mm / min during the test.

[0153] (4) Bending strength: determined according to ISO 178 method, test conditions are 2 mm / min.

[0154] (5) Notched impact strength: The notched impact strength of the material was tested using a cantilever pendulum impact tester. The impact strength was determined according to ISO 180-2001, with a notch depth of 2 mm and a pendulum energy of 2.75 J.

[0155] (6) Flame retardancy rating test: The flame center is placed at the midpoint of the lower edge of the sample, and the distance from the top of the burner to the lower end of the sample is 10mm. Maintain for 10 seconds. If the shape and position of the sample change during the combustion process, the burner should be adjusted accordingly. If there is molten material dripping during the test, the burner can be tilted to 45°. After burning for 10±0.5 seconds, move away from the burner at a speed of 300mm / min for at least 150mm. At the same time, start recording the afterflame time t1 (seconds). When the afterflame stops, immediately burn again for 10±0.5 seconds. After moving away, record the afterflame time t2 (seconds) and afterburn time t3 (seconds), and record the number of molten droplets. The flame retardancy rating is determined based on whether the molten droplets ignite the degreased cotton.

[0156]

[0157] Each embodiment provides 5 samples for testing and recording.

[0158] The performance test results are shown in Tables 1 and 2.

[0159] Table 1

[0160]

[0161] Table 2

[0162]

[0163]

[0164]

[0165] As shown in Table 1, by designing the raw materials for preparing flame-retardant polyamide 66 resin, this invention achieves a significant reduction in mechanical properties compared to polyamide 66 resin without any flame retardants. The polyamide 66 resin containing phosphorus-based, nitrogen-based, and silicone-based flame retardants provided by this invention exhibits no substantial decrease in mechanical properties. Its relative viscosity is 2.62-2.76, melting point is 261℃ or 262℃, tensile strength is 74-79 MPa, flexural strength is 90-94 MPa, and notched impact strength is 4.3-5.1 KJ / m². 2 .

[0166] As shown in Table 2, compared with polyamide 66 resin without any flame retardant, the flame retardant rating of polyamide 66 resin containing phosphorus-based flame retardant, nitrogen-based flame retardant and silicone-based flame retardant provided by the present invention is improved from V2 to V0, and the number of melt droplets is also significantly reduced (number of melt droplets ≤11). Moreover, the flame retardant effect of the group with added nitrogen-based flame retardant, silicone-based flame retardant and phosphorus-based flame retardant is better than that of the group without flame retardant and the group with only two flame retardants. Furthermore, the flame retardant effect of the system can be controlled by adjusting the ratio of flame retardants.

[0167] This invention further optimizes the overall performance of polyamide 66 resin by using 3-hydroxyphenylphosphonopropionic acid and / or aluminum aminotrimethylenephosphonate, melamine cyanurate, and silicone resin micro powder, further improving the flame retardant properties of polyamide 66 resin and mitigating the droplet problem of polyamide 66 resin, with a droplet count ≤7.

[0168] This invention further optimizes and improves the overall performance of flame-retardant polyamide 66 resin by using a specific third monomer and controlling the amount of the third monomer within a specific range.

[0169] In summary, this invention, through the design of the specific composition of flame-retardant polyamide 66 resin and the synergistic effect of phosphorus-based flame retardants, nitrogen-based flame retardants, and silicon-based flame retardants, has prepared a flame-retardant polyamide 66 resin with both high flame retardancy and good mechanical properties. Furthermore, the preparation method of the flame-retardant polyamide 66 resin provided by this invention is simple to operate, expanding the application market for flame-retardant polyamide 66 resin.

[0170] The applicant declares that the detailed process flow of this invention is illustrated by the above embodiments, but this invention is not limited to the above detailed process flow, that is, it does not mean that this invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A flame-retardant polyamide 66 resin, characterized in that, The raw materials for preparing the flame-retardant polyamide 66 resin include the following components in parts by weight: The mixture contains 85-98 parts of hexamethylenediamine and adipic acid, 2-8 parts of phosphorus-based flame retardant, 1-4 parts of nitrogen-based flame retardant, 2-5 parts of silicon-based flame retardant, and 0.1-2 parts of a third monomer. The molar ratio of hexamethylenediamine to adipic acid is (1 ~ 1.05):1; The phosphorus-based flame retardant is selected from 3-hydroxyphenylphosphonopropionic acid and / or aluminum aminotrimethylenephosphonate; The nitrogen-based flame retardant is selected from melamine cyanurate and / or melamine; The silicon-based flame retardant is selected from silicone resin micro powder and / or silicone oil; The third monomer is selected as an autolactam; The flame-retardant polyamide 66 resin is prepared by the following method, which includes the following steps: (1) Hexamethylenediamine and adipic acid undergo a salt formation reaction, and the pH is adjusted to obtain a polyamide 66 salt solution; (2) Mix the polyamide 66 salt solution with other raw materials for the preparation of flame retardant polyamide 66 and react to obtain the flame retardant polyamide 66 resin.

2. The flame-retardant polyamide 66 resin according to claim 1, characterized in that, The nitrogen-based flame retardant is melamine cyanurate.

3. The flame-retardant polyamide 66 resin according to claim 1, characterized in that, The silicon-based flame retardant is selected from silicon resin micro powder.

4. The flame-retardant polyamide 66 resin according to claim 1, characterized in that, The raw materials for preparing the flame-retardant polyamide 66 resin also include 0.1 to 1 part by weight of antioxidant.

5. The flame-retardant polyamide 66 resin according to claim 1, characterized in that, The raw materials for preparing the flame-retardant polyamide 66 resin also include 0.2 to 1 part by weight of heat stabilizer.

6. The flame-retardant polyamide 66 resin according to claim 5, characterized in that, The heat stabilizer is selected from any one or a combination of at least two of the following: copper acetate-potassium iodide, copper acetate-cuprous iodide-potassium iodide, copper acetate-potassium bromide, or copper acetate-cuprous bromide-potassium bromide.

7. The flame-retardant polyamide 66 resin according to claim 1, characterized in that, The raw materials for preparing the flame-retardant polyamide 66 resin also include 0.01 to 0.1 parts by weight of catalyst.

8. The flame-retardant polyamide 66 resin according to claim 7, characterized in that, The catalyst is selected from any one or a combination of at least two of phosphoric acid, phosphorous acid, hypophosphite organic compounds or hypophosphites.

9. A method for preparing flame-retardant polyamide 66 resin as described in any one of claims 1-8, characterized in that, The preparation method of the flame-retardant polyamide 66 resin includes the following steps: (1) Hexamethylenediamine and adipic acid undergo a salt formation reaction, and the pH is adjusted to obtain a polyamide 66 salt solution; (2) Mix the polyamide 66 salt solution with other raw materials for the preparation of flame retardant polyamide 66 and react to obtain the flame retardant polyamide 66 resin.

10. The preparation method according to claim 9, characterized in that, The salt formation reaction is carried out at a temperature of 50℃ to 80℃ for a time of 20 min to 30 min.

11. The preparation method according to claim 9, characterized in that, The salt formation reaction is carried out in the presence of a protective atmosphere and a solvent, including water.

12. The preparation method according to claim 9, characterized in that, After pH adjustment, the pH of the polyamide 66 salt solution is 7.00 ~ 7.

80.

13. The preparation method according to claim 9, characterized in that, The polyamide 66 salt solution has a mass percentage content of 40% to 60%.

14. The preparation method according to claim 9, characterized in that, The mixing temperature in step (2) is 50℃ ~ 80℃.

15. The preparation method according to claim 9, characterized in that, The reaction in step (2) includes the following steps: heating the reaction system until the pressure of the reaction system reaches 0.15 MPa ~ 0.20 MPa, and concentrating the mass concentration of the polyamide 66 salt solution to 60% ~ 70%; Continue heating until the reaction system pressure reaches 0.8 MPa ~ 1.3 MPa, concentrating the polyamide 66 salt solution to 70% ~ 90% by mass; continue heating until the reaction system pressure reaches 1.6 MPa ~ 2.0 MPa, concentrating the polyamide 66 salt solution to 92% ~ 97% by mass. Then, increase the temperature and decrease the pressure to drain the water, reducing the pressure of the reaction system to atmospheric pressure. Under the conditions of 260℃ ~ 290℃ and -0.01 MPa ~ -0.1 MPa, carry out the polymerization reaction for 5 min ~ 30 min.

16. The preparation method according to claim 9, characterized in that, The preparation method of the flame-retardant polyamide 66 resin specifically includes the following steps: (1) In a protective atmosphere, hexamethylenediamine, adipic acid and water are mixed and the salt formation reaction is carried out at 50℃ ~ 80℃ for 20 min ~ 30 min. The pH is adjusted to 7.00 ~ 7.80 to obtain a polyamide 66 salt solution with a mass concentration of 40% ~ 60%. (2) At 50℃ ~ 80℃, the polyamide 66 salt solution and other raw materials for the preparation of flame-retardant polyamide 66 are mixed and heated. When the pressure of the reaction system reaches 0.15 MPa ~ 0.20 MPa, the mass concentration of the polyamide 66 salt solution is concentrated to 60% ~ 70%. The temperature is further increased to the pressure of the reaction system to 0.8 MPa ~ 1.3 MPa, and the mass concentration of the polyamide 66 salt solution is concentrated to 70% ~ 90%. The temperature is further increased to the pressure of the reaction system to 1.6 MPa ~ 2.0 MPa, and the mass concentration of the polyamide 66 salt solution is concentrated to 92% ~ 97%. Then, the temperature is increased and the pressure is decreased to drain water. The pressure of the reaction system is reduced to normal pressure. The polymerization reaction is carried out at 260℃ ~ 290℃ and a pressure of -0.01 MPa ~ -0.1 MPa for 5 min ~ 30 min to obtain the flame-retardant polyamide 66 resin.

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