Gas-production arc-extinguishing polyamide composite material and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to a gas-production arc-extinguishing polyamide composite material and a preparation method thereof. The gas-producing arc-extinguishing polyamide composite material comprises polyamide resin, a gas-producing auxiliary agent and a processing auxiliary agent, the ratio of the polyamide resin to the gas-producing auxiliary agent to the processing auxiliary agent in percentage by weight is (85-99.8): (0.1-10): (0.1-5), a zinc compound is added to introduce zinc ions, the zinc ions are coordinated with oxygen atoms or nitrogen atoms in amide groups, and therefore the gas-producing arc-extinguishing polyamide composite material is obtained. Therefore, the stability of an amido bond is reduced, the amido bond is broken, more chain scission processes are further induced, the decomposition temperature of polyamide is reduced, the gas production time is shortened, gas can be quickly released and electric arcs can be inhibited when the electric arcs are generated, and the technical effects of safe and efficient gas production and arc extinguishing are achieved. The invention also provides a preparation method of the gas-producing arc-extinguishing polyamide composite material, and the technical problem of how to develop a safe and efficient novel gas-producing arc-extinguishing composite material is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a gas-generating arc-extinguishing polyamide composite material and a preparation method thereof. Background Art

[0002] Low-voltage circuit breakers, also commonly known as automatic air switches, can be used in electrical systems to prevent damage caused by overload or short circuit.

[0003] Gas-generating arc-extinguishing materials are important materials in the arc-extinguishing unit of low-voltage circuit breakers. They can be used to strengthen gas blowing and take away heat, help quickly extinguish the arc generated during the breaking process, and ensure the safe operation of the equipment. Gas-generating arc-extinguishing materials will produce a large amount of gas under the action of the arc, which can not only drive the arc to enter the arc-extinguishing grid faster, but also improve the dielectric recovery strength after the arc current passes zero. And in the gas generated by the gas-generating material, the higher the content of hydrogen with high thermal conductivity, the more significant its effect.

[0004] With the rapid development of economy, energy conservation and emission reduction and the large-scale promotion of clean energy, new low-voltage electrical appliances are required to have smaller size and higher breaking performance, which increases the necessity of extensive use of gas-generating materials. Traditional gas-generating materials are mostly red steel paper, which is a composite material combined by cellulose substrate and resin impregnation. It is easy to be affected by moisture and deformed during operation, and has low reliability. As a common thermoplastic material, polyamide has the advantages of easy processing, high heat resistance, large gas production after arc erosion, and less carbon residue.

[0005] On May 3, 2017, Chinese patent CN104559169B disclosed a flame-retardant gas-generating polyamide arc-extinguishing composite material and its preparation method and application. The flame-retardant gas-generating polyamide arc-extinguishing composite material includes components such as polyamide, polyamide prepolymer, arc-extinguishing metal compound, arc-extinguishing water-absorbing compound, arc-extinguishing gas-generating flame-retardant compound, gas-generating promoter and processing aid, which can generate gas to assist arc extinguishing. However, the gas-generating promoter used is a strong oxidant such as potassium nitrate. The boiling point of potassium nitrate is 400°C. When it comes into contact with or mixed with organic matter, reducing agent, flammable material, etc., it may cause combustion and explosion, and decompose to release toxic nitrogen oxide gas. Safety considerations should be taken into account during the use of raw materials.

[0006] On December 6, 2022, Chinese patent CN112708267B disclosed a polyamide composition for circuit breakers, its preparation method and application. The phosphorus-containing compound in the polyamide composition decomposes the polyamide under acidic conditions to release gas, thereby improving the arc extinguishing performance of the material. However, the effect of the phosphorus-containing compound on reducing the decomposition temperature of polyamide is not significant, and the hydrogen content in the melamine, melamine condensate or melamine urate components added in the scheme is calculated according to the molecular formula and the proportion of hydrogen is less than 4.8%. According to the literature, gas-producing materials should preferably be materials that produce more H2 components after being eroded by electric arc. Compared with the flame retardant in Chinese patent CN112708267B, the proportion of hydrogen in pure resins of polyamide PA6 and PA66 is more than twice that of the flame retardant. In theory, after being eroded by electric arc, polyamide resin can produce more hydrogen with high thermal conductivity to help cool and extinguish the arc.

[0007] Based on the above situation, it can be seen that developing a safe and efficient new gas-generating arc-extinguishing composite material is still a problem that technical personnel in this field need to solve. Summary of the invention

[0008] In order to solve the technical problem that a safe and efficient new gas-generating arc-extinguishing composite material has not yet been developed in the art, the present invention provides a gas-generating arc-extinguishing polyamide composite material, the components of which include: polyamide resin, gas-generating auxiliary agent and processing auxiliary agent; The weight percentage of the polyamide resin, the gas generating aid and the processing aid is (85-99.8): (0.1-10): (0.1-5).

[0009] In one embodiment, the polyamide resin is an aliphatic polyamide resin.

[0010] Furthermore, the aliphatic polyamide resin is any one of PA66, PA6, PA46, PA7, PA9, PA11, PA12, PA56, PA610, PA612, PA1010, PA1012 and PA1212, or a combination of any two of them.

[0011] In one embodiment, the gas generating auxiliary agent is a zinc compound.

[0012] Further, the zinc compound is any one of zinc stannate, zinc hydroxystannate, zinc borate, hydrated zinc borate, zinc oxide, zinc oxide, zinc hydroxide, zinc sulfide and zinc chloride, or a combination of any two of them.

[0013] In one embodiment, the processing aid is any one of an antioxidant, a lubricant, a mold release agent, a crystallization aid and a pigment additive, or a combination of any two of them.

[0014] Furthermore, the antioxidant is any one or any combination of hindered phenol antioxidants, semi-hindered phenol antioxidants, hindered amine antioxidants, phosphate antioxidants, phosphite antioxidants and copper salt antioxidants.

[0015] Furthermore, the hindered phenol antioxidant includes antioxidant 1010; and the phosphite antioxidant includes antioxidant 168.

[0016] The present invention also provides a method for preparing the gas-generating arc-extinguishing polyamide composite material as described above, comprising the following steps: Weigh the polyamide resin, the zinc compound and the processing aid according to weight percentage, mix them, and obtain a premix; The premix is ​​added into a twin-screw extruder through a main feeding port, melt-extruded, and granulated to obtain the gas-generating arc-extinguishing polyamide composite material.

[0017] In one embodiment, the twin-screw extruder has a melt extrusion temperature of 220-280° C., a screw aspect ratio of (35-60):1, and a screw speed of 300-500 rpm.

[0018] Compared with the prior art, the gas-generating arc-extinguishing polyamide composite material provided by the present invention can significantly reduce the decomposition temperature of polyamide under relatively mild conditions, shorten the gas production time, and improve the arc extinguishing efficiency, and has excellent gas production performance; when applied to low-voltage circuit breakers, it can quickly release gas when an arc is generated, and further suppress the arc through the action of the gas, thereby achieving the effect of safe and efficient gas production and arc extinguishing.

[0019] The present invention also provides a method for preparing a gas-generating arc-extinguishing polyamide composite material. The method is not affected by the reduction in the decomposition temperature of the composite material, can produce the gas-generating arc-extinguishing polyamide composite material with high quality, high efficiency and stability, and has significant practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is an example diagram of the TG / DTG curve provided based on Example 1 of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example 1 This embodiment provides a gas-generating arc-extinguishing polyamide composite material, which is prepared according to the following steps: 99.8% of PA66, 0.1% of zinc stannate and 0.1% of an antioxidant were weighed and mixed to obtain a premix; The premix is ​​added into a twin-screw extruder through a main feeding port, melt-extruded, and granulated to obtain the gas-generating arc-extinguishing polyamide composite material.

[0024] In this embodiment, preferably, the PA66 is commercially available polyhexamethylene adipamide, with a molecular formula of C 12 H 22 N2O2, relative viscosity is 2.67.

[0025] In this embodiment, preferably, the zinc stannate has a chemical formula of ZnSnO3 and a purity of ≥99%.

[0026] In this embodiment, preferably, the antioxidant is obtained by mixing antioxidant 1010 and antioxidant 168 in a weight percentage ratio of 1:1; the antioxidant 1010 is a commercially available hindered phenol antioxidant tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester; and the antioxidant 168 is a commercially available phosphite antioxidant tris(2,4-di-tert-butylphenyl) phosphite.

[0027] In this embodiment, preferably, the twin-screw extruder is provided with 10 barrel sections, and the temperatures of each zone from zone 1 to zone 10 are 220°C, 240°C, 250°C, 255°C, 260°C, 260°C, 260°C, 260°C, 270°C, the head temperature is 280°C, the screw aspect ratio is 40:1, and the screw speed is 350 rpm.

[0028] Example 2 This embodiment provides a gas-generating arc-extinguishing polyamide composite material, wherein, by weight percentage, the addition amount of PA66 is 99.3%, the addition amount of zinc stannate is 0.5%, and the addition amount of antioxidant is 0.2%. The remaining raw material composition, proportion, preparation steps and process parameters are the same as those in Example 1.

[0029] Example 3 This embodiment provides a gas-generating arc-extinguishing polyamide composite material, wherein, by weight percentage, the addition amount of PA66 is 98.8%, the addition amount of zinc stannate is 1%, and the addition amount of antioxidant is 0.2%. The remaining raw material composition, proportion, preparation steps and process parameters are the same as those in Example 1.

[0030] Example 4 This embodiment provides a gas-generating arc-extinguishing polyamide composite material, wherein, by weight percentage, the addition amount of PA66 is 98.3%, the addition amount of zinc stannate is 1.5%, and the addition amount of antioxidant is 0.2%. The remaining raw material composition, proportion, preparation steps and process parameters are the same as those in Example 1.

[0031] Example 5 This embodiment provides a gas-generating arc-extinguishing polyamide composite material, wherein, by weight percentage, the addition amount of PA66 is 94.8%, the addition amount of zinc stannate is 5%, and the addition amount of antioxidant is 0.2%. The remaining raw material composition, proportion, preparation steps and process parameters are the same as those in Example 1.

[0032] Example 6 This embodiment provides a gas-generating arc-extinguishing polyamide composite material, wherein, by weight percentage, the addition amount of PA66 is 89.8%, the addition amount of zinc stannate is 10%, and the addition amount of antioxidant is 0.2%. The remaining raw material composition, proportion, preparation steps and process parameters are the same as those in Example 1.

[0033] Example 7 This embodiment provides a gas-generating arc-extinguishing polyamide composite material, wherein zinc stannate is replaced by zinc borate; in terms of weight percentage, the amount of PA66 added is 89.8%, the amount of zinc borate added is 10%, and the amount of antioxidant added is 0.2%. The remaining raw material composition, proportion, preparation steps and process parameters are the same as those in Example 1.

[0034] In this embodiment, preferably, the zinc borate is 3.5-hydrate zinc borate with a chemical formula of 2ZnO·3B2O3·3.5H2O, wherein the ZnO content is 38.2±0.5% and the B2O3 content is 48.2±0.7%.

[0035] Example 8 This embodiment provides a gas-generating arc-extinguishing polyamide composite material, wherein zinc stannate is replaced by zinc oxide, and by weight percentage, the addition amount of PA66 is 97.9%, the addition amount of zinc oxide is 1.9%, and the addition amount of antioxidant is 0.2%. The remaining raw material composition, proportion, preparation steps and process parameters are the same as those in Example 1.

[0036] In this embodiment, preferably, the zinc oxide has a chemical formula of ZnO and a purity of ≥99%.

[0037] The present invention also provides the following comparative examples 1 to 4 for preparing a polyamide composite material: Comparative Example 1 The difference between this comparative example and Example 1 of the present invention is that the zinc stannate is replaced by an antioxidant in equal amount. The rest of the raw material composition, proportion, preparation steps and process parameters are the same as those of Example 1.

[0038] Comparative Example 2 The difference between this comparative example and Example 3 of the present invention is that: the PA66 is replaced by PA10T, and the zinc stannate is replaced by PA10T in equal amounts; the temperature of each zone of the twin-screw extruder is 250° C., 270° C., 280° C., 285° C., 290° C., 290° C., 290° C., 290° C., 300° C. from zone 1 to zone 10, and the die temperature is 310° C. The rest of the raw material composition, proportion, preparation steps and process parameters are the same as those in Example 3.

[0039] In this comparative example, PA10T is commercially available polydecane terephthalamide, with a relative viscosity of 2.0 and a molecular formula of C 18 H 26 N2O2.

[0040] Comparative Example 3 The difference between this comparative example and Example 3 of the present invention is that the PA66 is replaced by PA10T; the temperature of each zone of the twin-screw extruder is 250° C., 270° C., 280° C., 285° C., 290° C., 290° C., 290° C., 290° C., 300° C. from zone 1 to zone 10, and the head temperature is 310° C. The rest of the raw material composition, proportion, preparation steps and process parameters are the same as those in Example 3.

[0041] In this comparative example, PA10T is commercially available polydecane terephthalamide, with a relative viscosity of 2.0 and a molecular formula of C 18 H 26 N2O2.

[0042] Comparative Example 4 The difference between this comparative example and Example 6 of the present invention is that PA66 is replaced by PA10T; the temperature of each zone of the twin-screw extruder is 250° C., 270° C., 280° C., 285° C., 290° C., 290° C., 290° C., 290° C., 300° C. from zone 1 to zone 10, and the head temperature is 310° C. The rest of the raw material composition, proportion, preparation steps and process parameters are the same as those in Example 6.

[0043] In this comparative example, PA10T is commercially available polydecane terephthalamide, with a relative viscosity of 2.0 and a molecular formula of C 18 H 26 N2O2.

[0044] The decomposition temperature of the gas-generating arc-extinguishing polyamide composite materials prepared in Examples 1 to 8 and Comparative Examples 1 to 4 was tested by a thermogravimetric analyzer TGA at a heating rate of 100° C. / min to simulate their ability to decompose and generate gas after rapid heating.

[0045] TGA test obtains the weight loss percentage (thermogravimetric curve TG) and weight loss rate (differential thermogravimetric curve DTG) of the material as the temperature increases. Figure 1 As shown, the test results are listed in Table 1.

[0046] Table 1 Summary of TGA test results of polyamide composite materials prepared in Examples 1 to 8 and Comparative Examples 1 to 4

[0047] The lower the decomposition temperature of TGA, the easier it is to produce gas; the shorter the decomposition time, the faster the gas production speed, which is more conducive to gas blowing out arc. p is the temperature when the weight loss rate is the largest, which characterizes the difficulty of decomposition; T1 and T2 are the temperatures corresponding to half of the maximum weight loss rate; T2-T1 is the half-peak width of the DTG curve, which characterizes the time for decomposition to produce gas. The narrower the corresponding peak width, the faster the decomposition to produce gas.

[0048] Combination Figure 1 From the test results of Comparative Example 1 and Example 1 in Table 1, it can be seen that after a small amount of zinc stannate is added, the decomposition peak temperature of the gas-generating arc-extinguishing polyamide composite material decreases, and the half-peak width decreases, indicating that the gas-generating arc-extinguishing polyamide composite material provided by Example 1 can decompose and generate gas at a lower temperature, and the gas generation speed is also faster; in addition, the total weight loss percentage of Example 1 is also slightly higher than that of Comparative Example 1, and the carbonization amount is reduced, further indicating that the catalytic material of Example 1 produces more gas phase components.

[0049] According to the test results of Comparative Example 3 and Example 3, it can be seen that adding a small amount of zinc stannate to polyamide to reduce the decomposition peak temperature of the composite material and reduce the half-peak width has little effect on the polyamide PA10T with a lower hydrogen content, but has a significant regulating effect on the polyamide PA66 with a higher hydrogen content in the molecule, and the total weight loss percentage of Example 3 is higher than that of Comparative Example 3, indicating that the amount of gas phase component is higher after the additive catalyzes the polyamide PA66 material.

[0050] Comparing Comparative Example 3 with Comparative Example 2, it can be seen that after adding a small amount of zinc stannate, the decomposition peak temperature of the composite material is relatively reduced, indicating that the difficulty of decomposing and producing gas in the composite material is reduced, and the gas production and arc extinguishing effect is relatively good when used in circuit breakers. However, the half-peak width does not decrease significantly, indicating that the gas production rate does not change significantly.

[0051] The test results of Examples 1 to 6 show that with the increase in the amount of zinc stannate added, the decomposition peak temperature of the polyamide PA66 composite material decreases significantly and the half-peak width decreases, but these effects tend to be stable when the zinc stannate addition amount is ≥1.5% and ≥1%, respectively. Furthermore, when the zinc stannate addition amount is increased to 5% and 10%, the resin component is relatively reduced, and the material component that can be gasified and lose weight is reduced, thereby affecting the total weight loss. Based on this, considering the decomposition peak temperature, peak width, total weight loss ratio and cost, the optimal addition amount of zinc stannate is 0.5% to 1.5%.

[0052] Similarly, by comparing the test results of Comparative Example 4 with those of Example 6, it can be seen that when the addition amount of zinc stannate is increased to 10%, the difference in the effect of reducing the decomposition peak temperature of polyamide PA66 with a higher hydrogen content and polyamide PA10T with a lower hydrogen content is more significant. In addition, the total weight loss percentage of Comparative Example 4 is also significantly lower than that of Example 6, which indicates that the composite material provided in Comparative Example 4 produces less gas after catalysis.

[0053] In addition, according to the test results of Example 7 and Example 8, on the one hand, other zinc compounds such as zinc borate and zinc oxide can also reduce the decomposition temperature of polyamide PA66, making the material easier to decompose, but the effect is not as significant as zinc stannate; on the other hand, after adding zinc stannate and zinc oxide, the total weight loss percentage decreased significantly, and the decrease was higher than the amount of zinc compound added. This is because zinc borate and zinc oxide will catalyze the carbonization of polyamide at the same time, reducing the gasification part.

[0054] Furthermore, the polyamide composite materials provided in the above Examples 3 to 6 and Comparative Examples 1 to 3 were injection molded into gas-generating sheets using a single-screw injection molding machine and placed in a miniature circuit breaker (C65 structural platform) for short-circuit breaking test; wherein, 2 samples of each material were installed, and a rated breaking AC 6 kA test was carried out, the test was conducted three times, each time with an interval of 3 min, a closing angle of 60°, and the average values ​​of the three short-circuit test data were used for comparison, and the test results are listed in reference Table 2.

[0055] Table 2 Short circuit breaking test results of polyamide composite materials provided by Examples 3 to 6 and Comparative Examples 1 to 3

[0056] According to the data in Table 2, the gas-generating sheet made of the polyamide composite material obtained by adding zinc stannate can shorten the short-circuit breaking time of the circuit breaker and accelerate the arc extinguishing speed, thereby ensuring the breaking safety of the circuit breaker; and when the amount of zinc stannate added continues to increase, the resin component is relatively reduced, and the component of the material that can be gasified and weightless is reduced accordingly, its short-circuit breaking time is not significantly affected, and its arc extinguishing effect is still significant; in addition, compared with PA10T material, PA66 material has a more significant arc extinguishing effect, which also echoes the performance results in Table 1, such as lower decomposition temperature, faster decomposition speed, and greater total gas production.

[0057] In summary, the gas-generating arc-extinguishing polyamide composite material provided by the present invention can significantly reduce the decomposition temperature of polyamide under relatively mild conditions, shorten the gas production time, and improve the arc-extinguishing efficiency. This is because the zinc ions provided by the zinc compound in its components can act as Lewis acids, and by coordinating with the oxygen atoms or nitrogen atoms in the amide group, the stability of the amide bond is reduced, the amide bond breakage is promoted, and more chain breaking processes are induced; and the preferred zinc stannate can reduce the thermal reaction of polyamide to form rings and carbon at a lower temperature, so that it can produce more gas phase components, helping to improve the arc-extinguishing efficiency. In addition, since the temperature of the material modification process is generally below 350°C, reducing the decomposition temperature of the composite material by adding zinc compounds will not affect the material modification process, and the stable production of the material can still be guaranteed.

[0058] Although the terms such as arc extinguishing by gas production, decomposition rate, gasification weight loss, catalytic decomposition, catalytic carbonization, etc. are used more frequently in this article, the possibility of using other terms is not excluded. The use of these terms is only for the purpose of more conveniently describing and explaining the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas-generating arc-extinguishing polyamide composite material, characterized in that: Its components include: polyamide resin, gas generating aid and processing aid; The weight percentage of the polyamide resin, the gas generating aid and the processing aid is (85-99.8): (0.1-10): (0.1-5).

2. The gas-generating arc-extinguishing polyamide composite material according to claim 1, characterized in that: The polyamide resin is an aliphatic polyamide resin.

3. The gas-generating arc-extinguishing polyamide composite material according to claim 2, characterized in that: The aliphatic polyamide resin is any one of PA66, PA6, PA46, PA7, PA9, PA11, PA12, PA56, PA610, PA612, PA1010, PA1012 and PA1212, or a combination of any two of them.

4. The gas-generating arc-extinguishing polyamide composite material according to claim 1, characterized in that: The gas generating auxiliary agent is a zinc compound.

5. The gas-generating arc-extinguishing polyamide composite material according to claim 4, characterized in that: The zinc compound is any one of zinc stannate, zinc hydroxystannate, zinc borate, hydrated zinc borate, zinc oxide, zinc oxide, zinc hydroxide, zinc sulfide and zinc chloride, or a combination of any two of them.

6. The gas-generating arc-extinguishing polyamide composite material according to claim 1, characterized in that: The processing aid is any one of an antioxidant, a lubricant, a mold release agent, a crystallization aid and a pigment additive, or a combination of any two of them.

7. The gas-generating arc-extinguishing polyamide composite material according to claim 6, characterized in that: The antioxidant is any one or any combination of hindered phenol antioxidants, semi-hindered phenol antioxidants, hindered amine antioxidants, phosphate antioxidants, phosphite antioxidants and copper salt antioxidants.

8. The gas-generating arc-extinguishing polyamide composite material according to claim 7, characterized in that: The hindered phenol antioxidant includes antioxidant 1010; The phosphite antioxidant includes antioxidant 168.

9. A method for preparing the gas-generating arc-extinguishing polyamide composite material according to any one of claims 1 to 8, characterized in that: The following steps are involved: Weigh the polyamide resin, the zinc compound and the processing aid according to weight percentage, mix them, and obtain a premix; The premix is ​​added into a twin-screw extruder through a main feeding port, melt-extruded, and granulated to obtain the gas-generating arc-extinguishing polyamide composite material.

10. The method for preparing the gas-generating arc-extinguishing polyamide composite material according to claim 9, characterized in that: The twin-screw extruder has a melt extrusion temperature of 220-280° C., a screw length-to-diameter ratio of (35-60):1, and a screw speed of 300-500 rpm.

Images