Halogen-free flame-retardant polyamide material for low-voltage circuit breaker shell and preparation method thereof

Abstract

The invention relates to a halogen-free flame-retardant polyamide material for a low-voltage circuit breaker shell, and the halogen-free flame-retardant polyamide material for the low-voltage circuit breaker shell comprises the following components in parts by mass: polyamide, star polyamide, modified glass fiber, montmorillonite, a halogen-free flame retardant and an auxiliary agent, the hyperbranched polyamide derivative has a plurality of amino end groups; the modified glass fibers are glass fibers modified by gluconic acid. According to the preparation method, tetraethylenepentamine and acrylate are mixed for free radical polymerization, so that hyperbranched-structure star-shaped polyamide containing a large number of amino groups is obtained; meanwhile, gluconic acid is adopted to treat the glass fibers, and gluconic acid is introduced into the modified glass fibers, so that on one hand, the compatibility between the glass fibers and montmorillonite, polyamide and the like is improved, and the modified glass fibers are combined with other components more tightly;

Description

Technical Field

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

[0002] Low-voltage circuit breakers are electrical protection devices widely used in power systems, and their housing materials need to have high heat resistance, flame retardancy and mechanical strength. Polyamide (PA) material, 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 be thermally deformed in high-temperature environments, and their flame retardancy cannot meet the safety requirements of modern electrical equipment.

[0003] With the increasing requirements for electrical safety performance, the materials of low-voltage circuit breaker housings are gradually developing in the direction of halogen-free flame retardancy, high temperature resistance, and environmental friendliness. Halogen-free flame retardant polyamide materials, because they do not contain halogen components, have better environmental adaptability and excellent flame retardant properties, and are gradually becoming the preferred materials to replace traditional halogen flame retardant materials. However, the density of polyamide materials themselves is insufficient, which makes them easy to expand in high temperature environments, affecting the stability and flame retardant effect of the materials. To solve this problem, developing a technical solution that can improve the density of polyamide materials and enhance their thermal stability, flame retardancy and mechanical properties has become a current research hotspot.

[0004] At present, the existing low-voltage circuit breaker housing materials mostly use halogen flame retardants or traditional halogen-free flame retardant modified materials, but these materials often sacrifice the mechanical strength and stability of the materials while improving the flame retardant properties. Traditional polyamide materials are prone to thermal expansion in high temperature environments, resulting in unstable material structures, which in turn affects the housing strength and durability of low-voltage circuit breakers. This is mainly due to the flexibility of the polyamide molecular chain, which lacks sufficient cross-linking structure to improve its overall density. In addition, traditional halogen-free flame retardant modification methods usually rely on adding a large proportion of flame retardants, but too much flame retardant will lead to a decrease in the mechanical properties of the material, increase the difficulty of processing, and may even affect the appearance and processability of the material. Although glass fiber can enhance the mechanical strength of polyamide to a certain extent, its compatibility with the polyamide matrix is ​​poor, which often leads to insufficient tightness between the glass fiber and the polymer, affecting the overall performance of the material.

[0005] In summary, it is urgent to develop a new technical solution to solve the problems existing in the prior art. Summary of the invention

[0006] Based on this, the present invention develops a halogen-free flame-retardant polyamide material for low-voltage circuit breaker housing. The present invention introduces star-shaped polyamide and gluconic acid-modified glass fiber, both of which have higher cross-linking and intermolecular interaction, which helps to improve the comprehensive performance of the material; by gluconic acid-modified glass fiber, the compatibility of glass fiber and polyamide matrix can be improved, and the uniform dispersion of glass fiber can be promoted, thereby improving the mechanical properties and flame retardancy of the material, while ensuring environmental friendliness, and overcoming the defects existing in existing products.

[0007] One object of the present invention is to provide a halogen-free flame-retardant polyamide material for a low-voltage circuit breaker housing, wherein the halogen-free flame-retardant polyamide material for a low-voltage circuit breaker housing 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 a plurality of amino end groups;

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

[0012] Furthermore, the halogen-free flame retardant is selected from one or more of phosphinates, 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 auxiliary agent is selected from one or more of lubricants, stabilizers, toughening agents, and color additives.

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

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

[0018] Tetraethylenepentamine and acrylate are added to a solvent and heated to perform free radical polymerization; the product is then added to methanol for precipitation, and then allowed to stand for separation and washing to obtain the star-shaped polyamide;

[0019] S2. Preparation of modified glass fiber:

[0020] The glass fiber is immersed in gluconic acid and subjected to ultrasonic heating to obtain the modified glass fiber;

[0021] S3. The modified glass fiber, star-shaped polyamide and other ingredients are blended and added into 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] Furthermore, in step S1, the molar ratio of tetraethylenepentamine to acrylate is 0.5-1.5:1-2.

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

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

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

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

[0028] The invention adopts tetraethylenepentamine and acrylate to mix for free radical polymerization, thereby obtaining a star-shaped polyamide with a hyperbranched structure containing a large number of amino groups; at the same time, gluconic acid is used to treat glass fibers, and gluconic acid is introduced into the modified glass fibers, thereby introducing a large number of hydroxyl groups into the modified glass fibers; on the one hand, the compatibility between the modified glass fibers and components such as montmorillonite, polyamide, and halogen-free flame retardant is improved, so that the modified glass fibers are more closely combined with other components, and the modified glass fibers are more evenly distributed in the polyamide material, and when combustion occurs, the contact with external fire sources is more effectively isolated, thereby improving the flame retardancy of the polyamide material; on the other hand, compared with linear polyamide materials, since the star-shaped polyamide contains a large number of amino end groups, it can form multiple hydrogen bonding sites, and the star-shaped polyamide has a higher hydrogen bonding density. These hydrogen bonding sites not only form strong hydrogen bonding with the gluconic acid modified glass fibers, but also enhance the bonding force between the modified glass fibers and the star-shaped polyamide, so that the molecular chains are arranged closely, forming a dense three-dimensional cross-linked spatial network structure, so that the modified glass fibers and the star-shaped polyamide can be tightly combined, the interaction force is enhanced, and the density of the polyamide material is improved; secondly, the modified glass fibers can also form hydrogen bonds with the amino and oxygen-containing functional groups in the polyamide, thereby further enhancing the density of the polyamide material, thereby improving the mechanical strength; in addition, since the long chain segments in the hyperbranched star-shaped polyamide will be entangled with components such as polyamide, the connection between them is tighter, thereby further improving the compatibility and density between the components of the polyamide material, thereby effectively improving the mechanical strength and flame retardancy of the polyamide material. DETAILED DESCRIPTION

[0029] In order to more clearly illustrate the technical solution of the present invention, the following examples are listed. Unless otherwise stated, the raw materials, reactions and post-treatment methods shown in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0030] The words "preferred", "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0031] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers indicating, for example, the amounts of ingredients used in the specification and claims should be understood to be modified in all cases by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that vary depending on the desired properties to be obtained by the present invention.

[0032] Glass fiber, 301HP, length 4.5 mm, diameter 10 μm, purchased from Chongqing International Composite Company.

[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] Toughener, MAH-g-SEBS, FG1901 G, was purchased from Kraton.

[0039] Unless otherwise stated, the parts mentioned in the present invention refer to parts by mass.

[0040] Example 1

[0041] A halogen-free flame-retardant polyamide material for a low-voltage circuit breaker housing, the halogen-free flame-retardant polyamide material for a low-voltage circuit breaker housing comprising the following components in parts by mass:

[0042]

[0043] The method for preparing the halogen-free flame-retardant polyamide material for the low-voltage circuit breaker housing comprises the following steps:

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

[0045] Using methanol as solvent, under vacuum conditions, tetraethylene pentamine and methyl acrylate are mixed (the molar ratio of tetraethylene pentamine to methyl acrylate is 1:1), heated to 35°C for prepolymerization reaction for 48 hours, then heated to 60, 80, 100, and 120°C for heating reaction for 1 hour respectively, then heated to 140°C and heated for reaction for 2 hours for free radical polymerization, then added to methanol, and then added with anhydrous ether for precipitation, allowed to stand and separated, the crude product was washed with anhydrous ether, and dried to obtain the star-shaped polyamide;

[0046] S2. Preparation of modified glass fiber:

[0047] The glass fiber was immersed in gluconic acid (the molar ratio of the glass fiber to the gluconic acid was 1:3), and ultrasonically treated at 80°C for 10 h, and then filtered and washed to obtain the modified glass fiber;

[0048] S3. Blend the modified glass fiber, star-shaped polyamide and other ingredients according to the above-mentioned mass fractions, add them into a twin-screw extruder, heat to 250°C for extrusion, and then cool, dry and pelletize 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 a low-voltage circuit breaker housing, the halogen-free flame-retardant polyamide material for a low-voltage circuit breaker housing comprising the following components in parts by mass:

[0051]

[0052]

[0053] The method for preparing the halogen-free flame-retardant polyamide material for the low-voltage circuit breaker housing comprises the following steps:

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

[0055] Using methanol as solvent, under vacuum conditions, tetraethylene pentamine and methyl acrylate are mixed (the molar ratio of tetraethylene pentamine to methyl acrylate is 1:1), heated to 35°C for prepolymerization reaction for 48 hours, then heated to 60, 80, 100, and 120°C for heating reaction for 1 hour respectively, then heated to 140°C and heated for reaction for 2 hours for free radical polymerization, then added to methanol, and then added with anhydrous ether for precipitation, allowed to stand and separated, the crude product was washed with anhydrous ether, and dried to obtain the star-shaped polyamide;

[0056] S2. Preparation of modified glass fiber:

[0057] The glass fiber was immersed in gluconic acid (the molar ratio of the glass fiber to the gluconic acid was 1:3), and ultrasonically treated at 80°C for 10 h, and then filtered and washed to obtain the modified glass fiber;

[0058] S3. Blend the modified glass fiber, star-shaped polyamide and other ingredients according to the above-mentioned mass fractions, add them into a twin-screw extruder, heat to 250°C for extrusion, and then cool, dry and pelletize 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 a low-voltage circuit breaker housing, the halogen-free flame-retardant polyamide material for a low-voltage circuit breaker housing comprising the following components in parts by mass:

[0061]

[0062] The method for preparing the halogen-free flame-retardant polyamide material for the low-voltage circuit breaker housing comprises the following steps:

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

[0064] Using methanol as solvent, under vacuum conditions, tetraethylene pentamine and methyl acrylate are mixed (the molar ratio of tetraethylene pentamine to methyl acrylate is 1:1), heated to 35°C for prepolymerization reaction for 48 hours, then heated to 60, 80, 100, and 120°C for heating reaction for 1 hour respectively, then heated to 140°C and heated for reaction for 2 hours for free radical polymerization, then added to methanol, and then added with anhydrous ether for precipitation, allowed to stand and separated, the crude product was washed with anhydrous ether, and dried to obtain the star-shaped polyamide;

[0065] S2. Preparation of modified glass fiber:

[0066] The glass fiber was immersed in gluconic acid (the molar ratio of the glass fiber to the gluconic acid was 1:3), and ultrasonically treated at 80°C for 10 h, and then filtered and washed to obtain the modified glass fiber;

[0067] S3. Blend the modified glass fiber, star-shaped polyamide and other ingredients according to the above-mentioned mass fractions, add them into a twin-screw extruder, heat to 250°C for extrusion, and then cool, dry and pelletize 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 a low-voltage circuit breaker housing. 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 of the Netherlands, Hybrane PS2550) is used to replace the star-shaped polyamide, and the remaining components are the same as those in Example 1.

[0070] Comparative Example 2

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

[0072] Comparative Example 3

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

[0074] Test Example 1

[0075] The flame retardant polyamide materials of Example 1 and Comparative Examples 1-3 were subjected to performance tests.

[0076] Test method:

[0077] Flame retardancy test: The flame retardancy test is carried out according to the test standard of fire protection grade UL94.

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

[0079] Bending strength and bending modulus test: tested 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 of Example 1 and Comparative Examples 1-3

[0082] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Flame retardant 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] The test results show that the flame retardant properties and mechanical properties of the flame retardant polyamide material prepared in Example 1 are significantly better than those of 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 present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0085] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A halogen-free flame-retardant polyamide material for a low-voltage circuit breaker housing, characterized in that: The halogen-free flame-retardant polyamide material for the low-voltage circuit breaker housing includes the following components in parts by mass: in, The star-shaped polyamide is a hyperbranched polyamide derivative, and the hyperbranched polyamide derivative has a plurality of amino end groups; The modified glass fiber is a glass fiber modified by gluconic acid.

2. The halogen-free flame-retardant polyamide material for low-voltage circuit breaker housing according to claim 1, characterized in that: The halogen-free flame retardant is selected from one or more of phosphinates, diphosphates, melamine cyanurates, melamine polyphosphates and melamine oxalates.

3. The halogen-free flame-retardant polyamide material for low-voltage circuit breaker housing according to claim 1, characterized in that: The polyamide is selected from one or more of nylon 6 and nylon 66.

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

5. The method for preparing the halogen-free flame-retardant polyamide material for low-voltage circuit breaker housing according to any one of claims 1 to 4, characterized in that: The steps include: S1. Preparation of star-shaped polyamide: Tetraethylenepentamine and acrylate are added to a solvent and heated to perform free radical polymerization; the product is then added to methanol for precipitation, and then allowed to stand for separation and washing to obtain the star-shaped polyamide; S2. Preparation of modified glass fiber: The glass fiber is immersed in gluconic acid and subjected to ultrasonic heating to obtain the modified glass fiber; S3. The modified glass fiber, star-shaped polyamide and other ingredients are blended and added into 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.

6. The method for preparing the halogen-free flame-retardant polyamide material for low-voltage circuit breaker housing according to claim 5, characterized in that: In step S1, the temperature of the free radical polymerization is 60-145°C.

7. The method for preparing the halogen-free flame-retardant polyamide material for low-voltage circuit breaker housing according to claim 5, characterized in that: In step S1, the molar ratio of tetraethylenepentamine to acrylate is 0.5-1.5:1-2.

8. The method for preparing the halogen-free flame-retardant polyamide material for low-voltage circuit breaker housing according to claim 5, characterized in that: In step S2, the molar ratio of the glass fiber to the gluconic acid is 1:2-4.

9. The method for preparing the halogen-free flame-retardant polyamide material for low-voltage circuit breaker housing according to claim 5, characterized in that: In step S2, the temperature of the ultrasonic heating is 75-85°C.

10. The method for preparing the halogen-free flame-retardant polyamide material for low-voltage circuit breaker housing according to claim 5, characterized in that: In step S3, the extrusion temperature is set to 220-260°C.

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