Flame-retardant nylon composite material and preparation method thereof

Abstract

The invention relates to the technical field of materials, and discloses a flame-retardant nylon composite material and a preparation method thereof.The composite material is prepared by taking nylon 6 resin as a base material and glass fibers, a macromolecular multi-element flame retardant and the like as auxiliary materials through mixing, extrusion and granulation, the macromolecular multi-element flame retardant structurally contains a large number of ester groups, and the flame-retardant nylon composite material is a flame-retardant nylon composite material. On the one hand, the phosphorus element and the sulfur element contained in the structure can be used as an acid source, the nitrogen element can be used as a gas source, a synergistic flame-retardant effect can be formed between the phosphorus element and the sulfur element, an expanded carbon layer can be rapidly formed during combustion, and the flame-retardant performance of the material is improved. And external oxygen and heat are highly isolated, so that combustion is prevented from being continuously carried out inwards, and the flame retardant property of the composite material is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and in particular to a flame-retardant nylon composite material and a preparation method thereof. Background Art

[0002] Nylon composites are high-performance materials made by combining nylon resin with other reinforcing materials (such as glass fiber and carbon fiber) and additives (such as flame retardants and plasticizers) through a specific process. Nylon 6, one of the most common types of nylon, holds a key position in the composites field due to its excellent strength, wear resistance, and good processing properties. It is currently widely used in textiles, carpets, ropes, industrial belts, as well as in the automotive, electrical and electronic industries.

[0003] Despite its numerous advantages, nylon 6, without flame retardant modification, has a low flame retardancy rating, reaching only UL94 V-2 for vertical combustion. This means that if exposed to an open flame, nylon 6 will burn rapidly and may drip, spreading the flame. Therefore, flame retardant modification is particularly necessary for nylon 6 composites that must operate under high-temperature, flammable, and other special operating conditions.

[0004] Flame-retardant modification of nylon 6 composites is primarily achieved through the addition of flame retardants, typically inorganic, phosphorus, and halogen flame retardants. Inorganic flame retardants have a poor modification effect and require a large amount to achieve significant modification, which can impact the mechanical properties of the material. Organic flame retardants include halogen and phosphorus flame retardants. Halogen flame retardants have significant drawbacks, such as the production of large amounts of toxic fumes during combustion, and are therefore becoming less suitable. Small-molecule phosphorus flame retardants have compatibility issues with the matrix, are prone to precipitation, and are difficult to achieve sustained modification effects. Furthermore, single phosphorus flame retardants also exhibit poor modification effects. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In view of the deficiencies in the prior art, the present invention provides a flame retardant nylon composite material and a preparation method thereof.

[0007] (2) Technical solution

[0008] A method for preparing a flame-retardant nylon composite material, the composite material comprising the following raw materials measured in parts by weight:

[0009]

[0010] The preparation method comprises the following steps:

[0011] The first step is to weigh and prepare all the raw materials according to their weight;

[0012] In the second step, the raw materials are added to a high-speed mixer, the temperature is increased to 100-120°C, and the raw materials are mechanically stirred and mixed at a stirring rate of 1000-1500r / min for 30-60min. The raw materials are then transferred to a twin-screw extruder, and the extruder temperatures are controlled as follows: 190-200°C for the conveying section, 230-240°C for the melting section, 250-260°C for the shearing section, 230-240°C for the exhaust section, and 250-260°C for the extrusion section. After the melt extrusion process, the composite material can be obtained.

[0013] As a further embodiment of the present invention, the specific preparation method of the macromolecular multi-component flame retardant is as follows:

[0014] Add the reactive phosphorus-based flame retardant and N,N-dimethylformamide into a polymerization kettle filled with nitrogen, start stirring to form a uniform reaction liquid, then add the sulfur-containing chain extender into the polymerization kettle, and add the phase transfer catalyst at the same time. After the addition is completed, start heating, control the heating rate to 3-6°C / min, increase the temperature to 100-120°C, maintain, continue stirring and polymerization for 12-24 hours, remove the nitrogen, evaporate and remove the solvent, stop heating, cool and discharge the material, and purify it to obtain a macromolecular multi-component flame retardant.

[0015] As a further embodiment of the present invention, the specific preparation method of the reactive phosphorus-based flame retardant is as follows:

[0016] Aspartic acid, tris(2-chloroethyl) phosphate and toluene solvent are added to a reactor. After the addition is complete, stirring is started until a uniform mixed liquid is formed, and nitrogen is introduced for protection. An acid binding agent is added to the reactor, and then a heating program is started. The temperature in the reactor is maintained at 70-80°C. After stirring for 6-9 hours, heating is stopped, and the product is separated. After a post-processing process, a reactive phosphorus-based flame retardant can be obtained.

[0017] As a further embodiment of the present invention, the molar ratio of aspartic acid to tris(2-chloroethyl) phosphate is 1:1.

[0018] As a further embodiment of the present invention, the acid binding agent is triethylamine.

[0019] As a further embodiment of the present invention, the sulfur-containing chain extender is 3,6-dithia-1,8-octanediol.

[0020] As a further embodiment of the present invention, the phase transfer catalyst is any one of aminosulfonic acid, trifluoromethanesulfonic acid or p-toluenesulfonic acid.

[0021] In the above technical solution, aspartic acid and tris(2-chloroethyl) phosphate are first used as reactants, and the principle that the active amino group and the active halogen substituent in each other's structure can undergo a substitution reaction is utilized to prepare a reactive phosphorus-based flame retardant containing two equivalents of carboxyl substituents in the structure. Then, under phase transfer catalyst and high temperature conditions, it can undergo a continuous and uninterrupted condensation reaction with the hydroxyl substituents at both ends of the sulfur-containing chain extender to obtain a macromolecular multi-component flame retardant connected by ester bonds and having a block structure.

[0022] As a further embodiment of the present invention, the antioxidant is at least one of antioxidant 1010, antioxidant 1076 or antioxidant 168; the coupling agent is at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0023] As a further embodiment of the present invention, the inorganic filler is at least one of calcium carbonate, talc or silicon dioxide.

[0024] A flame retardant nylon composite material is prepared by adopting the above preparation method.

[0025] (3) Beneficial technical effects

[0026] The present invention prepares a macromolecular multi-component flame retardant as an additive and mixes it with nylon 6 resin. On the one hand, the macromolecular multi-component flame retardant contains a large number of ester groups in its structure, has good compatibility with nylon 6, and can effectively avoid the phenomenon of migration and precipitation. On the other hand, the phosphorus and sulfur elements contained in its structure can serve as acid sources, and the nitrogen element can serve as a gas source, which can form a synergistic flame retardant effect with each other. During combustion, an expanded carbon layer can be quickly formed to highly isolate external oxygen and heat, thereby preventing combustion from continuing to the inside, thereby greatly improving the flame retardant properties of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 This is the infrared analysis test diagram of the macromolecular multi-component flame retardant. DETAILED DESCRIPTION

[0029] To facilitate understanding of the present invention, the present invention will be described in more detail below. Preferred embodiments of the present invention are provided below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0030] Preparation Example 1

[0031] Preparation of macromolecular multi-component flame retardants:

[0032] Step 1: Add 0.6 g of aspartic acid, 1.29 g of tris(2-chloroethyl) phosphate and toluene solvent to a reactor. After the addition is complete, stir until a uniform mixture is formed, introduce nitrogen for protection, add 0.2 g of an acid-binding agent, triethylamine, to the reactor, then start the heating process, maintain the temperature in the reactor at 75° C., stir and react for 8 hours, stop heating, separate the product, and undergo post-processing to obtain a reactive phosphorus-based flame retardant;

[0033] Step 2: Add 0.5g of reactive phosphorus flame retardant and N,N-dimethylformamide to a polymerization kettle filled with nitrogen, start stirring to form a uniform reaction liquid, then add 0.24g of 3,6-dithia-1,8-octanediol to the polymerization kettle, and add 0.01g of p-toluenesulfonic acid at the same time. After the addition is completed, turn on the heating, control the heating rate to 5°C / min, raise the temperature to 110°C, maintain, continue stirring and polymerization for 18h, remove the nitrogen, evaporate to remove the solvent, stop heating, cool the material, and purify it to obtain a macromolecular multi-component flame retardant.

[0034] Figure 1 This is the infrared analysis test chart of the macromolecular multi-element flame retardant, where 3427cm -1 The characteristic absorption peak at 3309 cm is the NH characteristic absorption peak of secondary amine. -1 The characteristic absorption peak at 1745 cm is the characteristic absorption peak of hydroxyl group. -1 The characteristic absorption peak at 1251 cm is the C=O characteristic absorption peak of the ester group. -1 The characteristic absorption peak that appears at is the P=O characteristic absorption peak.

[0035] Example 1

[0036] A flame retardant nylon composite material, comprising the following raw materials measured in parts by weight:

[0037]

[0038] The preparation method of the composite material comprises the following steps:

[0039] The first step is to weigh and prepare all the raw materials according to their weight;

[0040] In the second step, the raw materials are added to a high-speed mixer, the temperature is raised to 100°C, and mechanically stirred and mixed at a stirring rate of 1000r / min for 60min. Then, the raw materials are transferred to a twin-screw extruder, and the extruder temperatures are controlled as follows: 195°C for the conveying section, 235°C for the melting section, 255°C for the shearing section, 235°C for the exhaust section, and 255°C for the extrusion section. After the melt extrusion process, the composite material can be obtained.

[0041] Example 2

[0042] A flame retardant nylon composite material, comprising the following raw materials measured in parts by weight:

[0043]

[0044]

[0045] The preparation method of the composite material comprises the following steps:

[0046] The first step is to weigh and prepare all the raw materials according to their weight;

[0047] In the second step, the raw materials are added to a high-speed mixer, the temperature is raised to 110°C, and mechanically stirred and mixed at a stirring rate of 1200r / min for 40 minutes. Then, the raw materials are transferred to a twin-screw extruder, and the extruder temperatures are controlled as follows: 195°C for the conveying section, 235°C for the melting section, 255°C for the shearing section, 235°C for the exhaust section, and 255°C for the extrusion section. After the melt extrusion process, the composite material can be obtained.

[0048] Example 3

[0049] A flame retardant nylon composite material, comprising the following raw materials measured in parts by weight:

[0050]

[0051] The preparation method of the composite material comprises the following steps:

[0052] The first step is to weigh and prepare all the raw materials according to their weight;

[0053] In the second step, the raw materials are added to a high-speed mixer, the temperature is raised to 120°C, and mechanically stirred and mixed at a stirring rate of 1500r / min for 30 minutes. Then, the raw materials are transferred to a twin-screw extruder, and the extruder temperatures are controlled as follows: 195°C for the conveying section, 235°C for the melting section, 255°C for the shearing section, 235°C for the exhaust section, and 255°C for the extrusion section. After the melt extrusion process, the composite material can be obtained.

[0054] Comparative Example 1

[0055] A flame retardant nylon composite material, comprising the following raw materials measured in parts by weight:

[0056]

[0057] The preparation method of the composite material comprises the following steps:

[0058] The first step is to weigh and prepare all the raw materials according to their weight;

[0059] In the second step, the raw materials are added to a high-speed mixer, the temperature is raised to 110°C, and mechanically stirred and mixed at a stirring rate of 1200r / min for 40 minutes. Then, the raw materials are transferred to a twin-screw extruder, and the extruder temperatures are controlled as follows: 195°C for the conveying section, 235°C for the melting section, 255°C for the shearing section, 235°C for the exhaust section, and 255°C for the extrusion section. After the melt extrusion process, the composite material can be obtained.

[0060] Comparative Example 2

[0061] A flame retardant nylon composite material, comprising the following raw materials measured in parts by weight:

[0062]

[0063] The preparation method of the composite material comprises the following steps:

[0064] The first step is to weigh and prepare all the raw materials according to their weight;

[0065] In the second step, the raw materials are added to a high-speed mixer, the temperature is raised to 110°C, and mechanically stirred and mixed at a stirring rate of 1200r / min for 40 minutes. Then, the raw materials are transferred to a twin-screw extruder, and the extruder temperatures are controlled as follows: 195°C for the conveying section, 235°C for the melting section, 255°C for the shearing section, 235°C for the exhaust section, and 255°C for the extrusion section. After the melt extrusion process, the composite material can be obtained.

[0066] Test Case

[0067] The composite materials in the examples and comparative examples were made into test specimens that met the test specifications. The limiting oxygen index test was performed according to the standard GB / T2406.1-2008. The results are recorded in the following table:

[0068] Table 1 - Test results

[0069] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Limiting oxygen index / % 32.3 32.6 32.5 27.1 24.6

[0070] According to the test results, the use of the macromolecular multi-component flame retardant prepared in Preparation Example 1 of the present invention as an additive can significantly improve the flame retardant properties of the nylon composite material, while the use of the conventional small molecule dimethyl phosphite flame retardant has a relatively poor flame retardant modification effect.

[0071] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0072] Based on the ideal embodiments of the present invention, and with reference to the above description, relevant personnel can make various changes and modifications without departing from the technical scope of the present invention. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a flame retardant nylon composite material, characterized in that: The composite material comprises the following raw materials measured in parts by weight: 65-75 parts of nylon 6 resin; 10-15 parts of glass fiber; 3-5 parts of macromolecular multi-component flame retardant; 0.5-1.5 parts of antioxidant; 1-2 parts of coupling agent; 5-10 parts of inorganic filler; The preparation method comprises the following steps: The first step is to weigh and prepare all the raw materials according to their weight; In the second step, the raw materials are added to a high-speed mixer, the temperature is increased to 100-120°C, and the raw materials are mechanically stirred and mixed at a stirring rate of 1000-1500r / min for 30-60min. The raw materials are then transferred to a twin-screw extruder, and the extruder temperatures are controlled as follows: 190-200°C for the conveying section, 230-240°C for the melting section, 250-260°C for the shearing section, 230-240°C for the exhaust section, and 250-260°C for the extrusion section. After the melt extrusion process, the composite material can be obtained.

2. The method for preparing a flame retardant nylon composite material according to claim 1, characterized in that: The specific preparation method of the macromolecular multi-component flame retardant is as follows: Add the reactive phosphorus-based flame retardant and N,N-dimethylformamide into a polymerization kettle filled with nitrogen, start stirring to form a uniform reaction liquid, then add the sulfur-containing chain extender into the polymerization kettle, and add the phase transfer catalyst at the same time. After the addition is completed, start heating, control the heating rate to 3-6°C / min, increase the temperature to 100-120°C, maintain, continue stirring and polymerization for 12-24 hours, remove the nitrogen, evaporate and remove the solvent, stop heating, cool and discharge the material, and purify it to obtain a macromolecular multi-component flame retardant.

3. The method for preparing a flame-retardant nylon composite material according to claim 2, characterized in that: The specific preparation method of the reactive phosphorus-based flame retardant is as follows: Aspartic acid, tris(2-chloroethyl) phosphate and toluene solvent are added to a reactor. After the addition is complete, stirring is started until a uniform mixed liquid is formed, and nitrogen is introduced for protection. An acid binding agent is added to the reactor, and then a heating program is started. The temperature in the reactor is maintained at 70-80°C. After stirring for 6-9 hours, heating is stopped, and the product is separated. After a post-processing process, a reactive phosphorus-based flame retardant can be obtained.

4. The method for preparing a flame-retardant nylon composite material according to claim 3, characterized in that: The molar ratio of aspartic acid to tris(2-chloroethyl) phosphate is 1:

1.

5. The method for preparing a flame-retardant nylon composite material according to claim 3, characterized in that: The acid binding agent is triethylamine.

6. The method for preparing a flame retardant nylon composite material according to claim 2, characterized in that: The sulfur-containing chain extender is 3,6-dithia-1,8-octanediol.

7. The method for preparing a flame-retardant nylon composite material according to claim 2, characterized in that: The phase transfer catalyst is any one of aminosulfonic acid, trifluoromethanesulfonic acid or p-toluenesulfonic acid.

8. The method for preparing a flame-retardant nylon composite material according to claim 1, characterized in that: The antioxidant is at least one of antioxidant 1010, antioxidant 1076 or antioxidant 168; the coupling agent is at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

9. A flame retardant nylon composite material, characterized in that: The method is as described in any one of claims 1 to 8.

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