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 a modified hydrotalcite additive and the like as auxiliary materials through mixing, extrusion and granulation, the existence of the multi-element flame-retardant macromolecular substance can improve the interfacial compatibility between the hydrotalcite and the nylon 6 resin matrix, promote the hydrotalcite to efficiently exert the enhancement advantage of the hydrotalcite and improve the mechanical strength of the composite material, and the multi-element flame-retardant macromolecular substance can form an expanded carbon layer to cover the surface of the material when the composite material burns, so that the flame-retardant property of the composite material is improved. According to the present invention, the hydrotalcite is added to prevent further combustion, the silicon element can be deposited on the surface of the carbon layer so as to enhance the structural strength of the carbon layer and avoid the collapse of the carbon layer, and the hydrotalcite has a certain flame retardation effect and can produce the inorganic-organic synergistic flame retardation effect so as to provide the excellent flame retardation property of the prepared composite material.

Description

Technical Field

[0001] The 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] As an important type of engineering plastic, nylon has been widely used in many industrial fields due to its excellent mechanical properties, wear resistance and chemical corrosion resistance. For example, nylon plays an irreplaceable role in the fields of automobiles, machinery, electronics, chemicals, etc. In addition, nylon materials also have good processing properties and can be processed into products of various shapes through various molding processes such as injection molding, extrusion, and blow molding.

[0003] Although nylon materials have many advantages, their flame retardant properties are relatively poor. The limiting oxygen index of unmodified nylon materials is less than 27%, which is a flammable material. Under extreme conditions such as high temperature or electric arc, nylon is easy to burn, and serious melting droplets will occur during the combustion process, becoming a secondary fire hazard. In addition, nylon may also release toxic gases during the combustion process, causing harm to the environment and human health. Therefore, improving the flame retardant properties of nylon is crucial to ensure safety in practical applications.

[0004] At present, the flame retardant modification of nylon materials is mainly blended flame retardant modification, which improves the flame retardant properties of nylon by blending flame retardants with nylon. However, this method has the problem of easy migration and precipitation of flame retardants, and it is difficult to ensure the flame retardant stability of nylon materials during long-term use. In addition, existing flame retardants have defects in practical applications. For example, inorganic flame retardants have poor flame retardant modification effects and require large amounts of addition, which can easily affect other properties of the material. Halogen-based flame retardants cause great damage to the environment after combustion, which is not in line with the concept of green environmental protection. The biggest defect of phosphorus-based small molecule flame retardants is migration and precipitation. Based on this, the present invention provides a flame retardant nylon composite material that can solve the problems existing in the prior art. Summary of the invention

[0005] 1. Technical issues to be 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] (II) Technical solution

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

[0009] 65-72 parts of nylon 6 resin, 2-3.5 parts of modified hydrotalcite additive, 10-15 parts of compatibilizer, 0.5-1.5 parts of antioxidant, 2-3 parts of lubricant;

[0010] The modified hydrotalcite additive is prepared by modifying the surface of hydrotalcite with a multi - functional flame - retardant macromolecular substance;

[0011] The preparation method of the nylon composite material includes the following steps:

[0012] First step, weigh each raw material according to parts by weight and set aside;

[0013] Second step, sequentially add the prepared raw materials into a mixer, control the temperature at 100 - 120 °C and the stirring rate at 1000 - 2000 r / min, mechanically stir and mix for 1 - 2 h, then feed the mixed material into a twin - screw extruder through a feeding port for melt extrusion granulation to obtain the nylon composite material.

[0014] Further preferably, the specific preparation method of the modified hydrotalcite additive includes the following steps:

[0015] Step 1, add hydrotalcite into an ethanol - aqueous solution with a volume fraction of 60 - 70%, control the ultrasonic frequency at 80 - 100 kHz, ultrasonically disperse for 20 - 40 min to form a uniform dispersion, then add a silane coupling agent into the dispersion, turn on the heating, maintain the temperature at 60 - 70 °C, keep warm for 4 - 8 h, and then separate the solid material to obtain silane - modified hydrotalcite;

[0016] Step 2, add the silane - modified hydrotalcite into toluene, continuously perform ultrasonic treatment until a uniform dispersion is formed, then introduce nitrogen protection, continue to add a multi - functional flame - retardant macromolecular substance into the dispersion, after adding, gradually raise the temperature to 70 - 80 °C, stir and keep warm for 8 - 12 h, then cool and discharge, and centrifuge to obtain the solid product to obtain the modified hydrotalcite additive.

[0017] Further preferably, in the above step 1, the silane coupling agent is selected from 3 - glycidoxypropyltrimethoxysilane or 3 - glycidoxypropyltriethoxysilane.

[0018] In the above technical solution, first, the surface of hydrotalcite is modified with an epoxy - silane coupling agent to obtain epoxy - silane - modified hydrotalcite. Then, by using the principle that the active epoxy group and secondary amine substituent contained in the structures of the multi - functional flame - retardant macromolecular substance and the epoxy - silane - modified hydrotalcite can undergo ring - opening addition reaction, the further modification of the silane - modified hydrotalcite is realized, and thus the modified hydrotalcite additive can be obtained.

[0019] Further preferably, in the above step 2, the specific preparation method of the multi - functional flame - retardant macromolecular substance includes the following steps:

[0020] Step S1: Add bis(dimethyl(phenyl)silyl)amine and tris(2-chloropropyl) phosphate into 1,4-dioxane. After adding, mechanically stir and mix evenly, and introduce nitrogen for protection. Then, heat up to 60-70 °C and keep stirring for 3-6 h. Evaporate and remove the solvent to obtain the silicon nitride intermediate material.

[0021] Step S2: Add the silicon nitride intermediate material, N,N'-dimethyl-1,3-propanediamine, and N,N-dimethylformamide into a polymerization kettle filled with nitrogen. After adding, start stirring. After forming a homogeneous reaction solution, start heating and raise the temperature to 70-80 °C. Keep stirring for 4-6 h, then add an acid-binding agent, further raise the temperature to 80-90 °C, continuously keep stirring for 12-18 h, and then cool down and discharge to obtain the multi-functional flame-retardant macromolecular substance.

[0022] Further preferably, in the above step S1, the molar ratio of bis(dimethyl(phenyl)silyl)amine to tris(2-chloropropyl) phosphate is 1:1.

[0023] Further preferably, in the above step S2, the molar ratio of the silicon nitride intermediate material to N,N'-dimethyl-1,3-propanediamine is 1:1-1.2.

[0024] Further preferably, in the above step S2, the acid-binding agent is triethylamine or pyridine.

[0025] In the above technical solution, by using bis(dimethyl(phenyl)silyl)amine and tris(2-chloropropyl) phosphate as reactants, utilizing the substitution reaction between the active secondary amino group and the halogen substituent in their respective structures, and controlling the dosage ratio of the two, a silicon nitride intermediate containing two equivalents of halogen substituents can be obtained. Then, using N,N'-dimethyl-1,3-propanediamine as a chain extender, under the action of an acid-binding agent, continuous and uninterrupted substitution with the silicon nitride intermediate is carried out, and finally a multi-functional flame-retardant macromolecular substance with an alternating connection structure is obtained.

[0026] Further preferably, the compatibilizer is any one of maleic anhydride grafted ethylene-octene copolymer, maleic anhydride grafted SEBS, or styrene-maleic anhydride copolymer.

[0027] Further preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 1098, or antioxidant BHT; the lubricant is polyethylene wax or calcium stearate.

[0028] A flame-retardant nylon composite material is prepared by using the above preparation method.

[0029] (III) Beneficial technical effects

[0030] The present invention prepares a modified hydrotalcite additive by modifying a multi-element flame-retardant macromolecular substance on the surface of hydrotalcite and carries out blending modification on nylon 6 resin. The multi-element flame-retardant macromolecular substance belongs to a transition structure between hydrotalcite and nylon 6 resin, which can effectively improve the interfacial compatibility between them, enabling the hydrotalcite to exist in the composite material in the form of physical cross-linking points, and then efficiently exerting its own strengthening advantages to improve the mechanical strength of the composite material. Moreover, the multi-element flame-retardant macromolecular substance structure contains a large amount of nitrogen, phosphorus, and silicon elements. Among them, nitrogen and phosphorus can form an expanded carbon layer during the combustion of the composite material, covering the surface of the material to prevent further combustion, and silicon elements can be deposited on the surface of the carbon layer to strengthen the structural strength of the carbon layer and avoid the collapse of the carbon layer. In addition, hydrotalcite itself has a certain flame-retardant effect, which can produce an inorganic-organic synergistic flame-retardant effect, making the prepared composite material have excellent flame-retardant performance. Brief Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0032] Figure 1 It is the FT-IR diagram of the multi-element flame-retardant macromolecular substance. Detailed Embodiments

[0033] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below. The preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0034] Preparation Example 1

[0035] Preparation of the modified hydrotalcite additive:

[0036] Step 1: Add 1.5 g of hydrotalcite to an ethanol aqueous solution with a volume fraction of 70%, control the ultrasonic frequency at 100 kHz, and ultrasonically disperse for 30 min to form a uniform dispersion. Then add 0.9 g of 3-glycidoxypropyltriethoxysilane to the dispersion, turn on the heating, maintain the temperature at 65 °C, keep warm for 6 h, and then separate the solid material to obtain the silane-modified hydrotalcite;

[0037] Step 2: Add 1.2 g of silane-modified hydrotalcite to toluene, continue ultrasonic treatment until a uniform dispersion is formed, introduce nitrogen protection, and continue to add 2.5 g of multi-component flame retardant macromolecular substances to the dispersion. After the addition is completed, the temperature is gradually increased to 75°C, stirred and kept warm for 9 hours, cooled and discharged, and the solid product is centrifuged to obtain a modified hydrotalcite additive.

[0038] The specific preparation method of the multi-element flame retardant macromolecular substance comprises the following steps:

[0039] Step S1, adding 0.8 g of bis(dimethyl(phenyl)silyl)amine and 0.92 g of tris(2-chloropropyl)phosphate to 1,4-dioxane, stirring mechanically to mix evenly, introducing nitrogen for protection, then heating to 65° C., stirring at this temperature for 4 h, evaporating and removing the solvent to obtain a silicon nitrogen intermediate material;

[0040] Step S2, add 0.5g of silicon nitrogen intermediate material, 0.1g of N,N'-dimethyl-1,3-propylenediamine and N,N-dimethylformamide to a polymerization kettle filled with nitrogen. After the addition, start stirring until a uniform reaction liquid is formed, turn on heating, raise the temperature to 75°C, keep stirring for 6 hours, add 0.01g of triethylamine, further raise the temperature to 90°C, keep stirring for 16 hours, cool and discharge the material, and obtain a multi-component flame-retardant macromolecular substance.

[0041] The infrared analysis test of the multi-component flame retardant macromolecular substance is shown in Figure 1 , of which 3412cm -1 The NH characteristic absorption peak appeared at 3000cm -1 ~3100cm -1 The characteristic absorption peak of the benzene ring skeleton appeared at 1210 cm -1 The characteristic absorption peak of P=O appeared at 1067cm -1 The Si-N characteristic absorption peak appeared at .

[0042] Example 1

[0043] A flame retardant nylon composite material is made of the following raw materials measured in parts by weight:

[0044] 65 parts of nylon 6 resin, 2 parts of modified hydrotalcite additive, 10 parts of compatibilizer, 10100.5 parts of antioxidant, 2 parts of lubricant polyethylene wax;

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

[0046] The first step is to weigh each raw material according to the weight and set aside;

[0047] Step 2: Add the prepared raw materials into a mixer in sequence, control the temperature at 100°C and the stirring rate at 2000 r / min, stir and mix mechanically for 1 h, then feed the mixed material into a twin-screw extruder through the feeding port, control the extruder temperature at 230°C and the rotation speed at 100 rpm, and carry out melt extrusion granulation to obtain the nylon composite material.

[0048] The modified hydrotalcite additive is the modified hydrotalcite additive prepared in Preparation Example 1; the compatibilizer is maleic anhydride grafted SEBS, and the same applies hereinafter.

[0049] Example 2

[0050] A flame-retardant nylon composite material is made of the following raw materials measured by weight parts:

[0051] 68 parts of nylon 6 resin, 3.2 parts of modified hydrotalcite additive, 12 parts of compatibilizer, 1 part of antioxidant 1098, 2.5 parts of lubricant calcium stearate;

[0052] The preparation method of the nylon composite material includes the following steps:

[0053] Step 1: Weigh each raw material according to the weight parts and set aside;

[0054] Step 2: Add the prepared raw materials into a mixer in sequence, control the temperature at 110°C and the stirring rate at 1500 r / min, stir and mix mechanically for 2 h, then feed the mixed material into a twin-screw extruder through the feeding port, control the extruder temperature at 230°C and the rotation speed at 100 rpm, and carry out melt extrusion granulation to obtain the nylon composite material.

[0055] Example 3

[0056] A flame-retardant nylon composite material is made of the following raw materials measured by weight parts:

[0057] 72 parts of nylon 6 resin, 3.5 parts of modified hydrotalcite additive, 15 parts of compatibilizer, 1.5 parts of antioxidant BHT, 3 parts of lubricant polyethylene wax;

[0058] The preparation method of the nylon composite material includes the following steps:

[0059] Step 1: Weigh each raw material according to the weight parts and set aside;

[0060] In the second step, the prepared raw materials are added to the mixer in turn, the temperature is controlled at 120°C, the stirring rate is 1000r / min, and the mechanical stirring is mixed for 2h. Then the mixed materials are fed into the twin-screw extruder through the feeding port, the extruder temperature is controlled at 230°C, the speed is controlled at 100rpm, and melt extrusion granulation is carried out to obtain nylon composite materials.

[0061] Comparative Example 1

[0062] A flame retardant nylon composite material is made of the following raw materials measured in parts by weight:

[0063] 68 parts of nylon 6 resin, 3.2 parts of hydrotalcite, 12 parts of compatibilizer, 10981 parts of antioxidant, 2.5 parts of lubricant calcium stearate;

[0064] The preparation method of the nylon composite material comprises the following steps:

[0065] The first step is to weigh each raw material according to the weight and set aside;

[0066] In the second step, the prepared raw materials are added to the mixer in turn, the temperature is controlled at 110°C, the stirring rate is 1500r / min, and the mechanical stirring is mixed for 2h. Then the mixed materials are fed into the twin-screw extruder through the feeding port, the extruder temperature is controlled at 230°C, the speed is controlled at 100rpm, and melt extrusion granulation is carried out to obtain nylon composite materials.

[0067] Comparative Example 2

[0068] A flame retardant nylon composite material is made of the following raw materials measured in parts by weight:

[0069] 68 parts of nylon 6 resin, 2 parts of multi-component flame retardant macromolecular substance, 12 parts of compatibilizer, 10981 parts of antioxidant, 2.5 parts of lubricant calcium stearate;

[0070] The preparation method of the nylon composite material comprises the following steps:

[0071] The first step is to weigh each raw material according to the weight and set aside;

[0072] In the second step, the prepared raw materials are added to the mixer in turn, the temperature is controlled at 110°C, the stirring rate is 1500r / min, and the mechanical stirring is mixed for 2h. Then the mixed materials are fed into the twin-screw extruder through the feeding port, the extruder temperature is controlled at 230°C, the speed is controlled at 100rpm, and melt extrusion granulation is carried out to obtain nylon composite materials.

[0073] The preparation method of the multi-component flame retardant macromolecular substance is shown in Preparation Example 1.

[0074] Comparative Example 3

[0075] A flame-retardant nylon composite material is made of the following raw materials measured by weight parts:

[0076] 68 parts of nylon 6 resin, 12 parts of compatibilizer, 1 part of antioxidant 1098, 2.5 parts of lubricant calcium stearate;

[0077] The preparation method of the nylon composite material includes the following steps:

[0078] First step, weigh each raw material according to the weight parts and set aside;

[0079] Second step, sequentially add the prepared raw materials into a mixer, control the temperature at 110 °C, the stirring rate at 1500 r / min, mechanically stir and mix for 2 h, then feed the mixed material into a twin-screw extruder through a feeding port, control the temperature of the extruder at 230 °C, the rotation speed at 100 rpm, and carry out melt extrusion granulation to obtain the nylon composite material.

[0080] Test Example

[0081] Make the composite materials in the examples and comparative examples into various test samples that meet the specifications, and conduct various performance tests. The results are shown in the following table:

[0082] Tensile strength / MPa <![CDATA[Impact strength / kJ / m 2 > Limiting oxygen index / % Example 1 171.7 79.1 33.1 Example 2 172.1 79.4 33.2 Example 3 172.0 79.2 33.1 Comparative example 1 167.5 75.6 27.5 Comparative example 2 159.5 65.0 31.8 Comparative example 3 158.9 64.8 26.2

[0083] Among them, the tensile strength is tested with reference to the standard GB / T 1040.3-2006;

[0084] The impact strength is tested with reference to the standard GB / T 14152-2001;

[0085] The limiting oxygen index is tested with reference to the standard GB / T 2406.1-2008.

[0086] Analyzing the test results, it can be seen that the composite material prepared with the modified hydrotalcite additive in Preparation Example 1 of the present invention shows excellent mechanical strength and flame retardancy. For the composite material prepared by directly adding hydrotalcite, due to the interfacial incompatibility problem, it is difficult for hydrotalcite to play its advantages efficiently, so the mechanical strength is reduced, and the multi-component flame retardant macromolecular substances are lost, and an effective expanded carbon layer cannot be formed, so the flame retardancy is greatly reduced. After replacing the modified hydrotalcite additive with multi-component flame retardant macromolecular substances, the reinforcing effect of hydrotalcite is lost, resulting in a significant reduction in the mechanical strength of the material, and the inorganic-organic synergistic flame retardancy cannot be formed, resulting in a slight reduction in the flame retardancy of the material.

[0087] Based on the inspiration of the ideal embodiments of the present invention, through the above description, relevant personnel can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A preparation method of a flame-retardant nylon composite material, characterized in that, The composite material is made of the following raw materials measured by weight parts: 65-72 parts of nylon 6 resin, 2-3.5 parts of modified hydrotalcite additive, 10-15 parts of compatibilizer, 0.5-1.5 parts of antioxidant, 2-3 parts of lubricant; The modified hydrotalcite additive is prepared by modifying a multi-functional flame retardant macromolecular substance on the surface of hydrotalcite; The preparation method includes the following steps: First step, weigh each raw material according to the weight parts and set aside; Second step, sequentially add the prepared raw materials into a mixer, control the temperature at 100-120 °C and the stirring rate at 1000-2000 r / min, mechanically stir and mix for 1-2 h, and then feed the mixed material into a twin-screw extruder through a feeding port for melt extrusion granulation to obtain the nylon composite material.

2. The preparation method of a flame-retardant nylon composite material according to claim 1, wherein The specific preparation method of the modified hydrotalcite additive includes the following steps: Step 1, add hydrotalcite into an ethanol aqueous solution with a volume fraction of 60-70%, control the ultrasonic frequency at 80-100 kHz, ultrasonically disperse for 20-40 min to form a uniform dispersion liquid, then add a silane coupling agent into the dispersion liquid, turn on the heating, maintain the temperature at 60-70 °C, keep warm for 4-8 h, and then separate the solid material to obtain the silane-modified hydrotalcite; Step 2, add the silane-modified hydrotalcite into toluene, continuously perform ultrasonic treatment until a uniform dispersion liquid is formed, then introduce nitrogen protection, continue to add a multi-functional flame retardant macromolecular substance into the dispersion liquid, after adding, gradually raise the temperature to 70-80 °C, stir and keep warm for 8-12 h, then cool down and discharge, and centrifuge to obtain the solid product to obtain the modified hydrotalcite additive.

3. The preparation method of a flame-retardant nylon composite material according to claim 2, characterized in that, In the first step, the silane coupling agent is selected from 3-glycidoxypropyltrimethoxysilane or 3-glycidoxypropyltriethoxysilane.

4. The preparation method of a flame-retardant nylon composite material according to claim 2, characterized in that, In the second step, the specific preparation method of the multi-functional flame retardant macromolecular substance includes the following steps: Step S1, add bis(dimethyl(phenyl)silyl)amine and tris(2-chloropropyl) phosphate into 1,4-dioxane, after adding, mechanically stir and mix evenly, and introduce nitrogen for protection, then raise the temperature to 60-70 °C, keep warm and stir for 3-6 h, evaporate and remove the solvent to obtain a silicon nitride intermediate; Step S2, add the silicon nitride intermediate, N,N'-dimethyl-1,3-propanediamine and N,N-dimethylformamide into a polymerization kettle filled with nitrogen, after adding, turn on the stirring, until a uniform reaction liquid is formed, then turn on the heating, raise the temperature to 70-80 °C, keep warm and stir for 4-6 h, then add an acid-binding agent, further raise the temperature to 80-90 °C, continuously keep warm and stir for 12-18 h, then cool down and discharge to obtain the multi-functional flame retardant macromolecular substance.

5. The preparation method of a flame-retardant nylon composite material according to claim 4, characterized in that, In the first step, the molar ratio of bis(dimethyl(phenyl)silyl)amine to tris(2-chloropropyl) phosphate is 1:

1.

6. The preparation method of a flame-retardant nylon composite material according to claim 4, characterized in that, In the second step, the molar ratio of the silicon nitride intermediate to N,N'-dimethyl-1,3-propanediamine is 1:1-1.

2.

7. The preparation method of a flame-retardant nylon composite material according to claim 4, wherein, In the second step, the acid-binding agent is triethylamine or pyridine.

8. The preparation method of a flame-retardant nylon composite material according to claim 1, wherein, The compatibilizer is any one of maleic anhydride grafted ethylene octene copolymer, maleic anhydride grafted SEBS or styrene-maleic anhydride copolymer.

9. The preparation method of a flame-retardant nylon composite material according to claim 1, characterized in that, The antioxidant is at least one of antioxidant 1010, antioxidant 1098 or antioxidant BHT; the lubricant is polyethylene wax or calcium stearate.

10. A flame-retardant nylon composite material, characterized in that, It is prepared by using the preparation method according to any one of claims 1-9.

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