Flame-retardant non-reinforced nylon composite and articles thereof

Abstract

The application belongs to the field of high polymer materials and discloses a kind of flame-retardant non-reinforced nylon composite material, by weight fraction, including the following raw material components: nylon resin 85~94 parts, flame retardant 6~15 parts, dispersing agent 0.1~2 parts, lubricant 0.1~1 part, antioxidant 0.1~1 part, other auxiliary agent 0~3 parts, the flame retardant is sheet-shaped melamine cyanurate;The dispersing agent is spherical dispersing agent with particle size of 10nm~200nm.This application introduces specific MCA flame retardant, and under the action of dispersing agent, gives MCA flame-retardant non-reinforced nylon composite material stable flame-retardant performance, and its flame-retardant grade can be stabilized to reach 0.8mm UL94 V-0 grade, even to 0.4mm UL94 V-0 grade.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to a flame-retardant unreinforced nylon composite material and its products. Background Technology

[0002] Melamine cyanurate (MCA) has a high nitrogen content and decomposes upon heating to produce non-flammable gases such as NH3, H2O, N2, CO2, and H2NCN. It has endothermic, cooling, and dilution effects on flammable gases and oxygen concentration, and is commonly used as a flame retardant modifier for thermoplastic resins, especially for flame-retardant unreinforced nylon systems. Only 6-8 wt% MCA can achieve a UL94 V-0 flame retardancy rating of 1.6 mm in unreinforced PA66 systems. However, traditional MCA flame-retardant nylon forms high-heat-containing droplets during combustion tests. These droplets often directly ignite absorbent cotton, or the non-flame droplets ignite absorbent cotton with high heat, resulting in inconsistent UL94 V0 flame retardancy test results with large fluctuations. The instability of melamine cyanurate's flame-retardant performance enhancement function is a major obstacle to its application.

[0003] Japanese patent JP2016155924A achieves a stable V0 flame retardant rating by using MCA of different particle sizes and adding polyol ester surfactants. However, obtaining MCA of different particle sizes requires a special synthesis process, which limits its applicability. Chinese patent CN101679743A uses polyamide as a matrix and melamine cyanuric acid as a flame retardant. By adding surfactants, specifically those containing at least one polyalkylene polyol fatty acid ester, a V0 flame retardant MCA flame-retardant polyamide composite material can be obtained. However, this method requires a very high amount of MCA, which severely affects the mechanical properties of the composite material, especially its toughness. Chinese patent CN108165002A uses C8-C18 mono- or di-saturated carboxylic acids (sebacic acid or stearic acid) as flame retardant stabilizers to improve the flame retardant properties of MCA flame retardant PA66, which can stably reach the UL94 V0 flame retardant level. However, the added small molecule carboxylic acid will accelerate the decomposition of nylon, affecting the service life of the product. Moreover, due to the effects of temperature and humidity during storage, it is easy to precipitate, which will cause appearance defects in the product. Chinese patent CN105111735A discloses a halogen-free flame-retardant nylon 66 composition and a method for modifying nylon 66. This invention uses 90-95 parts by weight of nylon 66; 5-10 parts by weight of melamine cyanurate halogen-free flame retardant; 1-5 parts by weight of melamine orthophosphate halogen-free flame retardant; 0.1-0.3 parts by weight of lubricant; 0.1-0.2 parts by weight of distilled water; and 0.5-2 parts by weight of optional additives to obtain flame-retardant nylon 66 with flame-retardant properties reaching UL94 V-0. However, this method has poor processability and versatility due to the addition of fluid substances.

[0004] Furthermore, electronic and electrical products are developing towards miniaturization, high integration, and high performance, resulting in increasingly lightweight and thinner housings. For example, signal relays and switching relays on the market today, including their coil frames and housings, have wall thicknesses below 1.0 mm, while connectors can achieve wall thicknesses as thin as approximately 0.4 mm. More and more electronic and electrical component manufacturers are placing increasingly stringent requirements on the flame-retardant properties of flame-retardant nylon, such as 0.8 mm UL94 V-0 rating, or even 0.4 mm UL94 V-0 rating, to meet the high flame-retardant requirements during their use. Therefore, developing MCA flame-retardant nylon composite materials with a flame-retardant rating of up to 0.8 mm UL94 V-0 and high flame-retardant stability is of great significance for broadening the application fields of MCA flame-retardant nylon composite materials. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a flame-retardant unreinforced nylon composite material and its preparation method. By introducing a specific MCA flame retardant and with the help of a dispersant, the MCA flame-retardant unreinforced nylon composite material is endowed with stable flame-retardant properties, and its flame-retardant rating can stably reach 0.8mm UL94 V-0 level, or even 0.4mm UL94 V-0 level.

[0006] The above-mentioned objective of this invention is achieved through the following technical solution:

[0007] A flame-retardant unreinforced nylon composite material, comprising the following raw material components by weight:

[0008] 85-94 parts of nylon resin,

[0009] 6-15 parts flame retardant

[0010] Dispersant 0.1~2 parts,

[0011] Lubricant 0.1~1 part,

[0012] Antioxidant 0.1~1 part,

[0013] Other auxiliary agents: 0-3 parts

[0014] The flame retardant is flaky melamine cyanurate;

[0015] The dispersant is a spherical dispersant with a particle size of 10 nm to 200 nm.

[0016] Optional, by weight, it includes the following raw material components:

[0017] 88-94 parts of nylon resin,

[0018] 6-12 parts flame retardant

[0019] Dispersant 0.1~1 part,

[0020] Lubricant 0.1~1 part,

[0021] Antioxidant 0.1~1 part,

[0022] Other additives: 0-3 parts.

[0023] Optionally, the flame retardant has a particle size of 0.2 μm to 1.5 μm.

[0024] Optionally, the nylon resin is selected from at least one of PA6, PA66, PA6 / 66 copolymer, PA46, PA610, PA612, and PA1010.

[0025] Optionally, the dispersant includes at least one of alumina, aluminum nitride, boron nitride, silicon dioxide, and titanium dioxide.

[0026] Optionally, the dispersant is surface-treated with a coupling agent.

[0027] Optionally, the coupling agent is a silane, titanate, phosphate, aluminate, or borate coupling agent.

[0028] Optionally, the other additives are selected from one or more of colorants, nucleating agents, toughening agents, light stabilizers, heat stabilizers, and mildew inhibitors.

[0029] This application also provides a nylon article, which is prepared by injection molding or compression molding of the composite material described in any of the foregoing technical solutions.

[0030] This application also provides the use of a dispersant for stabilizing the flame retardant properties of a flaky melamine cyanurate / nylon system, wherein the dispersant is a spherical dispersant with a particle size of 10 nm to 200 nm, and the dispersant is at least one of alumina, aluminum nitride, nitrogen nitride, silicon dioxide, and titanium dioxide.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) This invention introduces a specific morphology (sheet-like) MCA flame retardant into the nylon resin matrix and uses a spherical dispersant. With the help of its unique spherical morphology, it is easy to disperse evenly in the resin matrix and the advantage of the relatively large specific surface area of ​​the spherical structure. During the compounding and extrusion process, it can fully promote the uniform dispersion of sheet-like MCA in the nylon resin matrix, which greatly reduces the volume of drips generated in the combustion test of MCA flame-retardant nylon composite material. It achieves the dripping of small, low-heat molten droplets onto the degreased cotton, reducing the risk of molten droplets igniting the degreased cotton, and achieving the purpose of improving the flame retardant level and flame retardant stability of nylon composite material.

[0033] (2) The flame retardant unreinforced nylon composite material prepared by the present invention can stably reach the flame retardant level of 0.8mm UL94V0, or even 0.4mm UL94 V0. The resulting MCA flame retardant nylon composite material molded products have virtually no molten droplet ignition phenomenon when exposed to fire, which greatly reduces the risk of secondary fire and can significantly broaden the application field of MCA flame retardant nylon composite materials.

[0034] (3) The flame-retardant unreinforced nylon composite material prepared by the present invention not only has excellent flame-retardant properties, but also excellent strength and toughness (tensile strength ≥80MPa, notched impact strength of simply supported beam ≥5.5MPa), which is very suitable for preparing thin-walled precision products such as electronic connectors, terminals, motor coil frames, and connectors.

[0035] (4) Compared with traditional MCA flame-retardant nylon composite materials, the material formulation of the present invention is simple, and under the premise of meeting the same flame-retardant performance, the amount of MCA flame retardant can be reduced, reducing the risk of flame retardant precipitation, thereby improving the appearance quality of molded products. Attached Figure Description

[0036] Figure 1 SEM image of MCA flame retardant distribution in the cross-section of the test specimen in Example 9;

[0037] Figure 2 SEM image of MCA flame retardant distribution in the cross-section of test specimen for Comparative Example 5. Implementation

[0038] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0039] The raw materials used in the examples and comparative examples are all commercially available; unless otherwise specified, the reagents, methods and equipment used in this invention are conventional reagents, methods and equipment in this technical field.

[0040] The flame-retardant unreinforced nylon composite materials of all embodiments and comparative examples of this invention were prepared by the following method, and the components were weighed according to the weight parts in Tables 1 to 3:

[0041] S1. Weigh out the nylon resin, flame retardant, dispersant, lubricant, antioxidant and other additives and mix them evenly in a high-speed mixer to obtain a premix;

[0042] S2. The premix obtained in step S1 is added to a twin-screw extruder, and after melt extrusion and granulation, a flame-retardant unreinforced nylon composite material is obtained. In step S2, the twin-screw extruder has a screw length-to-diameter ratio of 40:1, a barrel temperature of 220–275℃, and a screw speed of 300–450 rpm.

[0043] The performance of the flame-retardant unreinforced nylon composite materials prepared in the following examples and comparative examples was tested using the following methods:

[0044] (1) Tensile strength (MPa): Tested according to GB / T1040.2-2006 standard;

[0045] (2) Bending strength (MPa): Tested according to GB / T9341-2008 standard;

[0046] (3) Notched impact strength (KJ / m) 2 Tested according to GB / T1043.1-2008 standard;

[0047] (4) Flame retardant performance: Standard UL94 test strips (10 strips per group) with thicknesses of 1.6mm, 0.8mm and 0.4mm were injection molded respectively. The test was conducted according to the UL94 standard, and the flame retardant rating and the number of strips in each group of 10 test strips that ignited during the combustion test were recorded.

[0048] The raw materials used in the examples and comparative examples are as follows:

[0049] raw material source Brand PA66 resin Shenma EPR27 PA6 resin Xinhui M2400 Flake-shaped MCA / 2.5μm Hangzhou Jiersi Flame Retardant Chemical Co., Ltd. JLS-MC25 Flake-shaped MCA / 1.5μm Nippon Chemical Co., Ltd. MC-6000 Flake-shaped MCA / 1μm Jinan Taixing Fine Chemical Co., Ltd. HT-211 Flake-shaped MCA / 0.7μm Jinan Taixing Fine Chemical Co., Ltd. HT-211 Flake-shaped MCA / 0.5μm Jinan Taixing Fine Chemical Co., Ltd. HT-211 Flake-shaped MCA / 0.2μm Jinan Taixing Fine Chemical Co., Ltd. HT-211 <![CDATA[Spherical Al2O3 / 10nm]]> Hefei AVIC Nanotechnology Development Co., Ltd. ZH-Alum150 <![CDATA[Spherical Al2O3 / 30 nm]]> Hefei AVIC Nanotechnology Development Co., Ltd. <![CDATA[ZH-Al2O330N]]> <![CDATA[Spherical Al2O3 / 50 nm]]> Hefei AVIC Nanotechnology Development Co., Ltd. <![CDATA[ZH-Al2O350N]]> <![CDATA[Spherical Al2O3 / 100 nm]]> Hefei AVIC Nanotechnology Development Co., Ltd. <![CDATA[ZH-Al2O3100N]]> <![CDATA[Spherical Al2O3 / 200 nm]]> Hefei AVIC Nanotechnology Development Co., Ltd. <![CDATA[ZH-Al2O3200N]]> <![CDATA[Spherical SiO2 / 10 nm]]> Bohuas Nanotechnology (Ningbo) Co., Ltd. Brofos-SiO2-S210 <![CDATA[Spherical SiO2 / 5μm]]> Suzhou Jinyi New Material Technology Co., Ltd. Q100 Rod-shaped MCA Shandong Gaoqi New Material Technology Co., Ltd. MCA-100 <![CDATA[Non-spherical Al2O3]]> Shanghai Huijing Asia Nanomaterials Co., Ltd. HG-D-5 <![CDATA[Non-spherical SiO2]]> Shanghai Huijing Asia Nanomaterials Co., Ltd. High-purity silicon dioxide

[0050] Examples 1-11.

[0051] Examples 1-11 provide a series of flame-retardant unreinforced nylon composite materials, and the specific formulations and properties are shown in Table 1 and Table 2.

[0052] Table 1: Formulations (parts) and performance of Examples 1-5

[0053]

[0054] Table 2. Formulations (parts) and properties of Examples 6-11

[0055]

[0056] Comparative examples 1-8.

[0057] Comparative Examples 1-8 provide a series of flame-retardant unreinforced nylon composite materials, and the specific formulations and properties are shown in Table 3.

[0058] Table 3. Formulations (parts) and properties of Comparative Examples 1-8

[0059]

[0060] The data in the tables above show that when flake-shaped MCA with a particle size of 0.2μm to 1.5μm is introduced into the nylon resin matrix as a flame retardant, and spherical dispersants (such as Al2O3 and SiO2) are used as dispersants, the flame retardancy rating of the prepared nylon composite materials can consistently reach UL94 V-0 level of 0.8mm. This means that none of the 10 test specimens ignited the absorbent cotton during the flame retardancy test. However, when adding an equal amount of conventional MCA flame retardant (rod-shaped structure), and with or without the addition of spherical dispersants, the flame retardancy rating of the prepared nylon composite materials (Comparative Examples 1-3), and when using flake-shaped MCA alone as a flame retardant (Comparative Examples 4-5), even with a larger particle size of the flake-shaped MCA (Comparative Example 4), can only reach a maximum of UL94 flame retardancy of 1.6mm. For a V0 rating, in the same batch of 10 test strips with a thickness of 0.8mm, more than half of them will produce large, high-heat molten droplets during the combustion test and ignite the degreased cotton. The flame retardant rating can only reach the 0.8mm UL94 V-2 rating.

[0061] As can be seen from Examples 9 and Comparative Examples 5-7, and Examples 11 and Comparative Example 8, introducing a small amount of spherical dispersant into the flake MCA flame-retardant nylon system not only ensures that the flame retardant rating of the prepared nylon composite material is stable at 0.8 mm UL94 V-0, but also maintains the comprehensive mechanical properties of the nylon composite material, especially the toughness of the material. Using flake MCA with a particle size of 0.5 μm to 1 μm as a flame retardant and spherical dispersant (Examples 7-11) can further improve the flame retardant performance of the nylon composite material, giving the nylon composite material a flame retardant rating of 0.4 mm UL94 V-0, and broadening the application range of small particle size MCA flame retardants.

[0062] From Example 9 (see Figure 1 ) and Comparative Example 5 (see Figure 2 The SEM images of the cross-section of the test specimen clearly show that, compared with the traditional MCA flame-retardant nylon composite material, the MCA flame retardant in the nylon matrix of the present invention is more uniformly dispersed, thereby promoting the stable flame-retardant properties of the nylon composite material.

[0063] It should be noted that the number of ignited specimens out of the 10 specimens in this embodiment does not represent a difference in flame retardancy rating; as long as one specimen ignites, it is considered a V2 rating. The purpose of the 10 specimens in this embodiment is to demonstrate flame retardancy stability; the national standard only requires 5 specimens.

[0064] The above-disclosed embodiments are only a few specific examples of this application, but this application is not limited thereto. Any variations that can be conceived by those skilled in the art should fall within the protection scope of this application.

Claims

1. A flame-retardant unreinforced nylon composite material, characterized in that, By weight, it includes the following raw material components: 85-94 parts of nylon resin, 6-15 parts flame retardant Dispersant 0.1~2 parts, Lubricant 0.1~1 part, Antioxidant 0.1~1 part, Other auxiliary agents: 0-3 parts The flame retardant is 0.5μm~1μm flake melamine cyanurate; the dispersant is a spherical dispersant with a particle size of 10nm~200nm, and the dispersant includes one or two of alumina and silicon dioxide.

2. The composite material according to claim 1, characterized in that, By weight, it includes the following raw material components: 88-94 parts of nylon resin, 6-12 parts flame retardant Dispersant 0.1~1 part, Lubricant 0.1~1 part, Antioxidant 0.1~1 part, Other additives: 0-3 parts.

3. The composite material according to claim 1 or 2, characterized in that, The nylon resin is selected from at least one of PA6, PA66, PA6 / 66 copolymer, PA46, PA610, PA612, and PA1010.

4. The composite material according to claim 1 or 2, characterized in that, The dispersant is surface-treated with a coupling agent.

5. The composite material according to claim 4, characterized in that, The coupling agent is a silane, titanate, phosphate, aluminate, or borate coupling agent.

6. The composite material according to claim 1 or 2, characterized in that, The other additives are selected from one or more of the following: colorants, nucleating agents, toughening agents, light stabilizers, heat stabilizers, and mildew inhibitors.

7. A nylon molded product, characterized in that, It is prepared by injection molding or compression molding from the composite material described in any one of claims 1 to 6.

8. The use of a dispersant for stabilizing the flame retardant properties of a flaky melamine cyanurate / nylon system, characterized in that, By weight, it includes the following raw material components: 85-94 parts of nylon resin, 6-15 parts flame retardant Dispersant 0.1~2 parts, Lubricant 0.1~1 part, Antioxidant 0.1~1 part, Other auxiliary agents: 0-3 parts The flame retardant is 0.5μm~1μm flake melamine cyanurate; the dispersant is a spherical dispersant with a particle size of 10nm~200nm, and the dispersant includes one or two of alumina and silicon dioxide.

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