A halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings and its preparation method

Abstract

This invention relates to a halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings. The halogen-free flame-retardant polyamide material comprises the following components in parts by weight: polyamide, star-shaped polyamide, modified glass fiber, montmorillonite, halogen-free flame retardant, and additives. The star-shaped polyamide is a hyperbranched polyamide derivative having multiple amino end groups. The modified glass fiber is gluconic acid-modified glass fiber. This invention obtains a star-shaped polyamide with a hyperbranched structure containing a large number of amino groups through free radical polymerization of tetraethylenepentamine and acrylate. Simultaneously, gluconic acid is used to treat the glass fiber, introducing gluconic acid into the modified glass fiber. This improves the compatibility between the glass fiber and montmorillonite, polyamide, etc., resulting in a tighter bond between the modified glass fiber and other components.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a halogen-free flame-retardant polyamide material for the housing of a low-voltage circuit breaker and its preparation method. Background Technology

[0002] Low-voltage circuit breakers are widely used electrical protection devices in power systems, and their housing materials need to possess high heat resistance, flame retardancy, and mechanical strength. Polyamide (PA), as an important engineering plastic, is widely used in the manufacture of low-voltage circuit breaker housings due to its excellent heat resistance, good electrical insulation, and mechanical properties. However, traditional polyamide materials may undergo thermal deformation at high temperatures, and their flame retardant properties cannot meet the safety requirements of modern electrical equipment.

[0003] With increasing demands for electrical safety, the materials used for low-voltage circuit breaker housings are gradually evolving towards halogen-free flame retardancy, high-temperature resistance, and environmental friendliness. Halogen-free flame-retardant polyamide materials, due to their absence of halogen components, exhibit better environmental adaptability and superior flame-retardant properties, gradually becoming the preferred alternative to traditional halogen-based flame-retardant materials. However, the insufficient density of polyamide materials makes them prone to expansion at high temperatures, affecting their stability and flame-retardant effect. To address this issue, developing a technical solution that improves the density of polyamide materials and enhances their thermal stability, flame retardancy, and mechanical properties has become a current research hotspot.

[0004] Currently, most low-voltage circuit breaker housing materials use halogenated flame retardants or traditional halogen-free flame-retardant modified materials. However, while improving flame retardant performance, these materials often sacrifice mechanical strength and stability. Traditional polyamide materials are prone to thermal expansion at high temperatures, leading to structural instability and affecting the housing strength and durability of low-voltage circuit breakers. This is mainly due to the flexibility of polyamide molecular chains, lacking sufficient cross-linking to improve overall density. Furthermore, traditional halogen-free flame-retardant modification methods typically rely on adding a large proportion of flame retardants, but excessive flame retardants can reduce mechanical properties, increase processing difficulty, and even affect the material's appearance and processability. While glass fiber can enhance the mechanical strength of polyamide to some extent, its poor compatibility with the polyamide matrix often results in insufficient bonding between the glass fiber and the polymer, affecting the overall performance of the material.

[0005] In conclusion, there is an urgent need to develop a new technical solution to address the problems existing in the current technology. Summary of the Invention

[0006] Based on this, the present invention develops a halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings. The present invention introduces star-shaped polyamide and gluconic acid-modified glass fiber, both of which have higher crosslinking properties and intermolecular interactions, contributing to improved overall material performance. The gluconic acid-modified glass fiber enhances the compatibility between the glass fiber and the polyamide matrix, promoting uniform dispersion of the glass fiber, thereby improving the material's mechanical properties and flame retardancy, while ensuring environmental friendliness, overcoming the shortcomings of existing products.

[0007] One object of the present invention is to provide a halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings, wherein the halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings comprises the following components in parts by weight:

[0008]

[0009] in,

[0010] The star-shaped polyamide is a hyperbranched polyamide derivative, and the hyperbranched polyamide derivative has multiple amine end groups;

[0011] The modified glass fiber is a gluconic acid-modified glass fiber.

[0012] Furthermore, the halogen-free flame retardant is selected from one or more of phosphonates, diphosphates, melamine cyanurate, melamine polyphosphate, and melamine oxalate.

[0013] Furthermore, the polyamide is selected from one or more of nylon 6 and nylon 66.

[0014] Furthermore, the diameter of the glass fiber is 10-30 μm.

[0015] Furthermore, the additive is selected from one or more of lubricants, stabilizers, toughening agents, and color additives.

[0016] This invention also provides a method for preparing the halogen-free flame-retardant polyamide material for the housing of the low-voltage circuit breaker, comprising the following steps:

[0017] S1. Preparation of star-shaped polyamide:

[0018] Tetraethylenepentamine and acrylate were added to a solvent and heated to carry out free radical polymerization; then the product was added to methanol, precipitated, allowed to stand, separated, and washed to obtain the star-shaped polyamide;

[0019] S2. Preparation of modified glass fiber:

[0020] The modified glass fiber is obtained by immersing glass fiber in gluconic acid and then subjecting it to ultrasonic heating.

[0021] S3. Modified glass fiber, star-shaped polyamide and other components are blended and added to a twin-screw extruder. After extrusion, the mixture is cooled, dried and pelletized to obtain the halogen-free flame-retardant polyamide material for the low-voltage circuit breaker housing.

[0022] Furthermore, in step S1, the temperature of the free radical polymerization is 60-145°C.

[0023] Further, in step S1, the molar ratio of tetraethylenepentamine to acrylate is 0.5-1.5:1-2.

[0024] Further, in step S2, the molar ratio of glass fiber to gluconic acid is 1:2-4.

[0025] Furthermore, in step S2, the temperature of the ultrasonic heating is 75-85℃.

[0026] Furthermore, in step S3, the extrusion temperature is set to 220-260℃.

[0027] The present invention has the following beneficial effects:

[0028] This invention utilizes a mixture of tetraethylenepentamine and acrylate for free radical polymerization to obtain a star-shaped polyamide with a hyperbranched structure containing a large number of amino groups. Simultaneously, gluconic acid is used to treat glass fibers, introducing gluconic acid into the modified glass fibers and introducing a large number of hydroxyl groups. On one hand, this improves the compatibility between the modified glass fibers and components such as montmorillonite, polyamide, and halogen-free flame retardants, resulting in a tighter bond between the modified glass fibers and other components, and a more uniform distribution of the modified glass fibers in the polyamide material. This more effectively isolates the polyamide material from external ignition sources during combustion, thereby improving its flame retardancy. On the other hand, compared to linear polyamide materials, star-shaped polyamides, due to the large number of amino end groups, can form multiple hydrogen bond sites, resulting in a higher hydrogen bond density. These hydrogen bonding sites not only form strong hydrogen bonds with gluconic acid-modified glass fibers, enhancing the bonding force between the modified glass fibers and star-shaped polyamides, resulting in a tighter arrangement of molecular chains and the formation of a dense three-dimensional cross-linked spatial network structure, but also enable the modified glass fibers and star-shaped polyamides to bond tightly together, strengthening the interaction force and improving the density of the polyamide material. Secondly, the modified glass fibers can also form hydrogen bonds with the amino and oxygen-containing functional groups in the polyamide, further enhancing the density of the polyamide material and thus improving its mechanical strength. In addition, because the long chain segments in the hyperbranched star-shaped polyamides entangle with the polyamide and other components, the interconnections are even tighter, further improving the compatibility and density of the various components of the polyamide material, thereby effectively improving the mechanical strength and flame retardancy of the polyamide material. Detailed Implementation

[0029] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0030] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0031] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​varying according to the desired performance to be obtained according to the invention.

[0032] Glass fiber, 301HP, 4.5mm in length, 10μm in diameter, purchased from Chongqing International Composites Co., Ltd.

[0033] Halogen-free flame retardant, Exolit OP1312.

[0034] Polyamide, Nylon 66, EPR27.

[0035] Montmorillonite, Nanomer I.34TCN.

[0036] Stabilizer, stabilizer 1098.

[0037] Lubricant, zinc stearate.

[0038] Toughening agent, MAH-g-SEBS, FG1901 G, purchased from Kronen.

[0039] Unless otherwise stated, the number of parts mentioned in this invention refers to parts by mass.

[0040] Example 1

[0041] A halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings, wherein the halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings comprises the following components in parts by weight:

[0042]

[0043] The preparation method of the above-mentioned halogen-free flame-retardant polyamide material for the housing of low-voltage circuit breakers includes the following steps:

[0044] S1. Preparation of star-shaped polyamide:

[0045] Using methanol as a solvent, tetraethylenepentamine and methyl acrylate (molar ratio of tetraethylenepentamine to methyl acrylate is 1:1) were blended under vacuum and heated to 35°C for 48 h for prepolymerization. Then, the mixture was heated to 60, 80, 100, and 120°C for 1 h each, and then heated to 140°C for 2 h for free radical polymerization. The product was then added to methanol, followed by the addition of anhydrous diethyl ether to precipitate it. After standing and separation, the crude product was washed with anhydrous diethyl ether and dried to obtain the star-shaped polyamide.

[0046] S2. Preparation of modified glass fiber:

[0047] Glass fiber was soaked in gluconic acid (molar ratio of glass fiber to gluconic acid was 1:3), ultrasonically treated at 80°C for 10 hours, and then filtered and washed to obtain modified glass fiber.

[0048] S3. According to the above-mentioned mass proportions, the modified glass fiber, star-shaped polyamide and other components are blended, added to a twin-screw extruder, heated to 250°C, extruded, cooled, dried and pelletized to obtain the halogen-free flame-retardant polyamide material for the low-voltage circuit breaker housing.

[0049] Example 2

[0050] A halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings, wherein the halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings comprises the following components in parts by weight:

[0051]

[0052]

[0053] The preparation method of the above-mentioned halogen-free flame-retardant polyamide material for the housing of low-voltage circuit breakers includes the following steps:

[0054] S1. Preparation of star-shaped polyamide:

[0055] Using methanol as a solvent, tetraethylenepentamine and methyl acrylate (molar ratio of tetraethylenepentamine to methyl acrylate is 1:1) were blended under vacuum and heated to 35°C for 48 h for prepolymerization. Then, the mixture was heated to 60, 80, 100, and 120°C for 1 h each, and then heated to 140°C for 2 h for free radical polymerization. The product was then added to methanol, followed by the addition of anhydrous diethyl ether to precipitate it. After standing and separation, the crude product was washed with anhydrous diethyl ether and dried to obtain the star-shaped polyamide.

[0056] S2. Preparation of modified glass fiber:

[0057] Glass fiber was soaked in gluconic acid (molar ratio of glass fiber to gluconic acid was 1:3), ultrasonically treated at 80°C for 10 hours, and then filtered and washed to obtain modified glass fiber.

[0058] S3. According to the above-mentioned mass proportions, the modified glass fiber, star-shaped polyamide and other components are blended, added to a twin-screw extruder, heated to 250°C, extruded, cooled, dried and pelletized to obtain the halogen-free flame-retardant polyamide material for the low-voltage circuit breaker housing.

[0059] Example 3

[0060] A halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings, wherein the halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings comprises the following components in parts by weight:

[0061]

[0062] The preparation method of the above-mentioned halogen-free flame-retardant polyamide material for the housing of low-voltage circuit breakers includes the following steps:

[0063] S1. Preparation of star-shaped polyamide:

[0064] Using methanol as a solvent, tetraethylenepentamine and methyl acrylate (molar ratio of tetraethylenepentamine to methyl acrylate is 1:1) were blended under vacuum and heated to 35°C for 48 h for prepolymerization. Then, the mixture was heated to 60, 80, 100, and 120°C for 1 h each, and then heated to 140°C for 2 h for free radical polymerization. The product was then added to methanol, followed by the addition of anhydrous diethyl ether to precipitate it. After standing and separation, the crude product was washed with anhydrous diethyl ether and dried to obtain the star-shaped polyamide.

[0065] S2. Preparation of modified glass fiber:

[0066] Glass fiber was soaked in gluconic acid (molar ratio of glass fiber to gluconic acid was 1:3), ultrasonically treated at 80°C for 10 hours, and then filtered and washed to obtain modified glass fiber.

[0067] S3. According to the above-mentioned mass proportions, the modified glass fiber, star-shaped polyamide and other components are blended, added to a twin-screw extruder, heated to 250°C, extruded, cooled, dried and pelletized to obtain the halogen-free flame-retardant polyamide material for the low-voltage circuit breaker housing.

[0068] Comparative Example 1

[0069] A halogen-free flame-retardant polyamide material for low-voltage circuit breaker housings. The difference between this comparative example and Example 1 is that step S1 is removed, and an equal mass of hyperbranched polyamide ester (purchased from DSM Hybrane BV, Netherlands, Hybrane PS2550) is used to replace the star-shaped polyamide. All other components are the same as in Example 1.

[0070] Comparative Example 2

[0071] A halogen-free flame-retardant polyamide material for the housing of a low-voltage circuit breaker. The difference between this comparative example and Example 1 is that step S2 is removed, and the modified glass fiber is replaced with an equal mass of unmodified glass fiber. The other components and preparation methods are the same as in Example 1.

[0072] Comparative Example 3

[0073] A halogen-free flame-retardant polyamide material for the housing of a low-voltage circuit breaker. The difference between this comparative example and Example 1 is that step S1 is removed, and an equal mass of nylon 66 is used to replace the star-shaped polyamide. All other components are the same as in Example 1.

[0074] Test Example 1

[0075] The performance of the flame-retardant polyamide materials of Example 1 and Comparative Examples 1-3 was tested.

[0076] Test method:

[0077] Flame retardancy test: Flame retardancy test is conducted according to the UL94 fire rating test standard.

[0078] Tensile strength test: Tested in accordance with GB / T1040.

[0079] Bending strength and bending modulus tests: conducted in accordance with GB / T 9341-2008.

[0080] The test results are shown in Table 1:

[0081] Table 1. Performance test results of flame-retardant polyamide materials in Examples 1 and 1-3.

[0082] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Flame retardancy V-0 V-0 V-1 V-1 Tensile strength (MPa) 148 141 136 133 Bending strength (MPa) 223 212 202 203 Flexural modulus (MPa) 9630 9524 9453 9468

[0083] Test results show that the flame retardant polyamide material prepared in Example 1 has significantly better flame retardant and mechanical properties than the flame retardant polyamide materials in Comparative Examples 1-3.

[0084] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0085] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A halogen-free flame-retardant polyamide material for low voltage circuit breaker housings, characterized in that, The low-voltage circuit breaker shell uses a halogen-free flame-retardant polyamide material comprising the following components by mass fraction: Polyamide 40-50 parts Star polyamide 10-15 parts Modified glass fiber 6-10 parts Montmorillonite 2-4 parts Halogen-free flame retardant 10-20 parts Auxiliary agent 0.2-1 part Among them, The star polyamide is a hyperbranched polyamide derivative, and the hyperbranched polyamide derivative has multiple amine end groups; The modified glass fiber is a glass fiber modified by gluconic acid; The preparation method of the low-voltage circuit breaker shell uses a halogen-free flame-retardant polyamide material, characterized by comprising the following steps: S1. Preparation of star polyamide: Add tetraethylenepentamine and acrylate into the solvent, heat for free radical polymerization; then add the product into methanol, and then precipitate, stand and separate, wash, and then obtain the star polyamide; S2. Preparation of modified glass fiber: Soak the glass fiber in gluconic acid and heat under ultrasonic to obtain the modified glass fiber; S3. Blend the modified glass fiber, star polyamide and other components, add them into a double-screw extruder, extrude, cool, dry and cut into particles to obtain the low-voltage circuit breaker shell uses a halogen-free flame-retardant polyamide material; The halogen-free flame retardant is selected from one or more of hypophosphite, secondary phosphite, melamine cyanurate, melamine polyphosphate and melamine oxalate; The polyamide is selected from one or more of nylon 6 and nylon 66; In step S1, the molar ratio of tetraethylenepentamine to acrylate is 0.5-1.5:1-2; In step S2, the molar ratio of glass fiber to gluconic acid is 1:2-4.

2. The low-voltage circuit breaker shell uses a halogen-free flame-retardant polyamide material according to claim 1, characterized in that The auxiliary agent is selected from one or more of lubricants, stabilizers, toughening agents and color additives.

3. The low-voltage circuit breaker shell uses a halogen-free flame-retardant polyamide material according to claim 1, characterized in that In step S1, the temperature of the free radical polymerization is 60-145℃.

4. The low-voltage circuit breaker shell uses a halogen-free flame-retardant polyamide material according to claim 1, characterized in that In step S2, the temperature of the ultrasonic heating is 75-85℃.

5. The halogen-free flame retardant polyamide material for low voltage circuit breaker housing according to claim 1, characterized in that, In step S3, the temperature of the extrusion is 220-260℃.

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