Halogen-free flame-retardant nylon nano composite material and preparation method thereof

Abstract

The invention discloses a halogen-free flame-retardant nylon nano composite material and a preparation method thereof, and belongs to the technical field of high polymer material modification. The composite material is prepared by taking nylon resin as a matrix, adding specific modified attapulgite, a flexibilizer, an antioxidant and the like, and preparing the composite material by a kneading machine or a screw extruder. Wherein the modified attapulgite is obtained by modifying natural attapulgite with phytic acid and a coupling agent, the addition amount of the modified attapulgite is small (0.5-10 parts by weight), but the flame retardant property and the mechanical property of the material can be remarkably improved. The invention also provides a preparation method of the modified attapulgite and the composite material. The invention has the advantages that the nylon composite material can reach excellent flame retardant grade (such as UL94 V0) under the condition of low additive amount by utilizing the synergistic effect of natural and environment-friendly phytic acid and the nano mineral attapulgite, meanwhile, the mechanical property is improved, and the nylon composite material is suitable for the fields of electronic appliances, new energy automobiles and the like which have harsh requirements on material performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high polymer material modification, and relates to a halogen-free flame-retardant nylon nanocomposite material and a preparation method thereof. BACKGROUND

[0002] With the acceleration of the high-density and miniaturization trend of electronic products, the traditional electronic appliances have increasingly stringent requirements for the flame-retardant performance of materials. In order to achieve the ideal flame-retardant effect, a large amount of flame retardants (such as melamine cyanurate MCA, polybrominated styrene, and antimony trioxide) need to be added, but this may cause problems such as cost increase and material performance decline.

[0003] CN104448801A discloses a halogen-free flame-retardant polyamide with high gloss and low warping and a preparation method thereof. This technology adds an organic phosphite salt flame retardant, but the compatibility of the organic phosphite salt flame retardant with nylon is poor, and a large amount of the organic phosphite salt flame retardant needs to be added to achieve good flame-retardant performance. With the increase of the amount of the flame retardant, the injection molding appearance is poor.

[0004] CN112759924A discloses an ultra-high flow high-halogen flame-retardant nylon material for an electric vehicle connector. This technology adds polybrominated styrene, antimony trioxide, nano-zirconium hydrogen phosphate, and cadmium oxide, and can be well applied to ultra-thin parts. However, with the increasing environmental protection requirements of the European Union, the use of halogen-containing materials is greatly hindered.

[0005] At present, the development of nylon materials tends to be more inclined to halogen-free flame-retardant materials. For example, patents CN108587145A and CN109957246A both use halogen-free flame retardants. However, in the injection molding process of thin-walled products, a very high processing temperature is required. At present, halogen-free flame retardants are easily affected by environmental factors such as temperature and humidity and are prone to precipitation, which reduces the safety and stability of the materials.

[0006] Under this background, the flame-retardant nylon technology is developing towards high efficiency, environmental protection, and compounding.

[0007] The increasing integration of electronic products (such as 5G devices and micro sensors) requires materials to achieve higher flame-retardant grades (such as UL94 V0) in limited space. Traditional general-purpose nylon cannot meet the requirements, and its flame-retardant performance needs to be enhanced. For example, the flame-retardant grade of the electric control box material has been improved from 3.0mm V0 to 2.5mm V0. Traditional halogen-based flame retardants are gradually eliminated due to environmental restrictions, and halogen-free flame retardants (such as phosphorus-based and nitrogen-based) need to be added in a large amount to achieve V0 grade, which leads to an increase in material density and cost. In addition, the poor compatibility of the flame retardant with nylon may affect the mechanical properties.

[0008] Therefore, it is an urgent problem to be solved to develop a nylon product with high flame-retardant and high strength performance. SUMMARY

[0009] In view of the deficiencies in the prior art, the present application provides a nylon product formula with excellent mechanical properties and good flame retardant properties. The product is widely used in the fields of electronic appliances, connectors, new energy vehicles and other high-temperature-resistant materials, and is a high-performance engineering material.

[0010] The present application particularly relates to a novel reinforcing agent which improves both impact strength and flame retardant properties. By adding the agent, the mechanical properties and flame retardant properties of nylon can be significantly improved.

[0011] To achieve the above object, the present application is implemented by the following technical solutions: A nylon product with excellent flame retardant properties and good mechanical properties is developed. The composition formula has the following characteristics: the amount of filler added is small (<10%), the product has good mechanical properties, is particularly suitable for thin-walled products, and the main raw materials are from natural substances, are environmentally friendly and low in price.

[0012] The main implementation approach is to prepare a natural attapulgite modified by phytic acid and a coupling agent. The material has high phosphorus content and good compatibility with the nylon matrix, and can significantly improve the flame retardant properties and mechanical properties of polyamide. The modified attapulgite prepared above is mixed with the nylon matrix, and common antioxidants, toughening agents and lubricants are added, and the mixture is granulated in a double screw according to a certain proportion, and finally the mechanical properties and flame retardant grade are tested.

[0013] The nylon can be nylon 6, nylon 66, or aromatic nylon containing benzene rings, such as nylon 6T, nylon 5T, PA9T, PA10T, MXD6, etc.

[0014] The natural nanometer mineral is mainly attapulgite. Attapulgite (also known as palygorskite) is a natural hydrous magnesium-aluminum silicate clay mineral with unique nano-porous structure and physical and chemical properties, and is widely used in agriculture, industry and other fields.

[0015] The antioxidant is added in a certain amount to improve the aging resistance of the product and prolong the service life of the product. The main components of the antioxidant are traditional hindered phenolic antioxidants, phosphite antioxidants, amine antioxidants and thioester antioxidants, etc.

[0016] The antioxidant is one or a combination of several.

[0017] Among them, in order to improve the compatibility of the attapulgite and the nylon matrix, the coupling agent is mainly silane coupling agent KH550 / KH560 / KH570, titanate coupling agent 105 / 102 / 311W, aluminate coupling agent 1618 / 181, etc. The addition of the coupling agent is one or a combination of several.

[0018] The flame retardant mainly plays a role in improving the flame retardant grade of the product. In the present patent, the flame retardant is mainly phytic acid, and more specifically, it refers to phytic acid modified attapulgite. The phytic acid modified attapulgite is filled into nylon, which significantly improves the flame retardant grade of the nylon. Phytic acid is a natural organic phosphoric compound, which is widely distributed in the plant kingdom, especially in legume seeds, grain bran and germ, and is the main form of phosphorus storage in plants. Its chemical structure can be represented as (C6H 18 O 24 P6).

[0019] The kneading device is a plastic modification mixing device such as a double screw extruder or a vacuum banbury mixer.

[0020] The preparation steps of the phytic acid modified attapulgite are as follows: After the attapulgite is pickled, washed to neutral and dried, it is ground into powder and dispersed in water to form a suspension. Phytic acid and silane coupling agent are added in turn for stepwise modification. After heating reaction, the product is centrifuged, washed, dried and crushed to obtain the modified attapulgite finished product.

[0021] All raw materials are taken by weight percentage, and a plastic high-speed stirrer is used to stir at a speed of 600 r / min~800 r / min and a temperature of 0~30℃ for 10~20 min to make them fully mixed and uniform. A double screw extruder or a single screw extruder is used to extrude and granulate the above mixture.

[0022] High-speed stirrer: Suzhou Lixin Special Purpose Machinery Co., Ltd. Extruder: Nanjing Koyamaki Chemical Engineering Equipment Co., Ltd. Injection molding machine: Ningbo Haitian Plastic Machinery Group Co., Ltd. Mechanical test method: ISO 527-2 Flame retardant test method: UL94 (1mm).

[0023] The beneficial effects of the present application are: a kind of phosphorus-containing efficient flame retardant (modified attapulgite) is prepared, which is used for the modification of nylon. After adding 5 parts of the modified attapulgite, the performance of the nylon is greatly improved, mainly in the aspects of mechanical properties and flame retardant properties. The tensile strength is increased by 90.4%, and the flame retardant grade is improved from HB to V-0 (1mm). DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0025] Attapulgite: Chuzhou City Xingming Mining Co., Ltd. Phytic acid: Hebei Hongtao Biological Engineering Co., Ltd. Coupling agent: Nanjing Shuguang Silane Chemical Co., Ltd. Attapulgite modification example 1 a) Soak the attapulgite in concentrated hydrochloric acid for more than 4 hours, then wash with deionized water until the washed water is neutral. Put the pretreated attapulgite into an oven and dry for 12 hours.

[0026] b) Take the attapulgite out of the oven and grind it into powder with a mortar. The particle size is controlled to be 100 μm.

[0027] c) A certain amount of attapulgite is added to water under high-speed stirring to prepare a suspension with a concentration of 5% (wt), and stirred at high speed in a 60°C water bath for 2 hours.

[0028] d) According to the ion exchange capacity of phytic acid to attapulgite of 1.5:1, weigh the phytic acid and add it to the attapulgite suspension.

[0029] e) Prepare a silane coupling agent KH550 ethanol solution, wherein the concentration of the coupling agent ethanol solution is 10%.

[0030] f) Add the coupling agent ethanol solution to the attapulgite aqueous solution, heat to 80°C, and heat and stir in an 80°C water bath for 4 hours. The amount of coupling agent added is 2% of the mass of attapulgite.

[0031] g) Finally, centrifuge the solution, take the solid, and wash it with ethanol and deionized water for 2-3 times respectively.

[0032] h) Dry for 12 hours, crush, and control the particle size to be 100 μm.

[0033] i) Finally, put the modified attapulgite into a 50°C vacuum drying oven for drying and standby, to obtain modified attapulgite-1#.

[0034] Attapulgite modification example 2 a) Soak the attapulgite in concentrated hydrochloric acid for more than 12 hours, then wash with deionized water until the washed water is neutral. Put the pretreated attapulgite into an oven and dry for 12 hours.

[0035] b) Take the attapulgite out of the oven and grind it into powder with a mortar. The particle size is controlled to be 100 μm.

[0036] c) A certain amount of palygorskite is added to water under high speed stirring to form a suspension with a concentration of 20% (wt). The suspension is stirred at high speed in a 60°C water bath for 2 h.

[0037] d) Phytic acid is weighed according to the ratio of 1:1 of the ion exchange capacity of phytic acid to palygorskite and added to the palygorskite suspension.

[0038] e) Titanate coupling agent 311W is configured into an ethanol solution, wherein the concentration of the coupling agent ethanol solution is 20%.

[0039] f) The coupling agent ethanol solution is added to the palygorskite water solution, and the temperature is raised to 80°C. The solution is heated and stirred in an 80°C water bath for 4 h. The amount of coupling agent added is 2% of the mass of the palygorskite.

[0040] g) Finally, the solution is centrifuged, and the solid is taken out and washed with ethanol and deionized water for 2-3 times, respectively.

[0041] h) The solid is dried in an oven for 12 h and crushed to a particle size of 100 μm.

[0042] i) Finally, the modified palygorskite is dried in a vacuum drying oven at 50°C and ready for use. Modified palygorskite-2# is obtained.

[0043] Example 3 of modification of palygorskite a) Palygorskite is soaked in concentrated hydrochloric acid for more than 12 h, and then washed with deionized water until the washed water is neutral. The pretreated palygorskite is dried in an oven for 12 h.

[0044] b) The palygorskite is taken out of the oven and crushed into powder with a mortar. The particle size is controlled to be 100 μm.

[0045] c) A certain amount of palygorskite is added to water under high speed stirring to form a suspension with a concentration of 20% (wt). The suspension is stirred at high speed in a 60°C water bath for 2 h.

[0046] d) Phytic acid is weighed according to the ratio of 0.5:1 of the ion exchange capacity of phytic acid to palygorskite and added to the palygorskite suspension.

[0047] e) Silane coupling agent KH 570 is configured into an ethanol solution, wherein the concentration of the coupling agent ethanol solution is 20%.

[0048] f) The coupling agent ethanol solution is added to the palygorskite water solution, and the temperature is raised to 80°C. The solution is heated and stirred in an 80°C water bath for 4 h. The amount of coupling agent added is 2% of the mass of the palygorskite.

[0049] g) Finally, the solution is centrifuged, and the solid is taken out and washed with ethanol and deionized water for 2-3 times, respectively.

[0050] h) Dry for 12 hours, crush, and control the particle size at 100 μm.

[0051] i) Finally, put the modified palygorskite into a vacuum drying oven at 50°C for drying, ready for use. Modified palygorskite-3# is obtained.

[0052] Nylon 66 relative viscosity 2.4, Huitian YN2400 Nylon 6 relative viscosity 2.45, Haiyang HY2500A MA-g-POE: Mitsui MA8530 The antioxidants mentioned in this patent are the well-known BASF 1098 and 168 in the industry, and their main function is to reduce the degradation of nylon during processing. All examples have been added, and the amount is consistent, which is 0.2 parts (i.e. 0.1 part of BASF 1098 and 0.1 part of BASF 168).

[0053] Composite Example 1 Nylon 66 100 parts, modified palygorskite-1# 0.5 parts, antioxidant 0.2 parts.

[0054] (1) Take all raw materials by weight fraction, use a plastic high-speed stirrer, control the speed at 800 r / min, and stir at 80°C for 10 minutes to make them fully mixed and uniform; (2) Granulate the mixed material through a double screw extruder, and test the mechanical properties and flame retardant properties of the sample according to the method described above.

[0055] Composite Example 2 Nylon 66 100 parts, modified palygorskite-2# 1 part, antioxidant 0.2 parts.

[0056] (1) Take all raw materials by weight fraction, use a plastic high-speed stirrer, control the speed at 800 r / min, and stir at 80°C for 10 minutes to make them fully mixed and uniform; (2) Granulate the mixed material through a double screw extruder, and test the mechanical properties and flame retardant properties of the sample according to the method described above.

[0057] Composite Example 3 Nylon 66 100 parts, modified palygorskite-1# 5 parts, antioxidant 0.2 parts.

[0058] (1) Take all raw materials by weight fraction, use a plastic high-speed stirrer, control the speed at 800 r / min, and stir at 80°C for 10 minutes to make them fully mixed and uniform; (2) Granulate the mixed material through a double screw extruder, and test the mechanical properties and flame retardant properties of the sample according to the method described above.

[0059] Composite Example 4 Nylon 66 100 parts, modified palygorskite-1# 3 parts, MA-g-POE 5 parts, antioxidant 0.2 parts.

[0060] (1) Take all raw materials by weight fraction, use a high-speed plastic mixer, control the speed at 800 r / min, and stir for 10 minutes at 80°C to make them fully mixed and uniform; (2) Granulate the mixed material through a twin-screw extruder, and test the mechanical properties and flame retardant properties of the sample according to the method described above.

[0061] Composite Example 5 Nylon 6 100 parts, modified palygorskite-1# 1 part, antioxidant 0.2 parts.

[0062] (1) Take all raw materials by weight fraction, use a high-speed plastic mixer, control the speed at 800 r / min, and stir for 10 minutes at 80°C to make them fully mixed and uniform; (2) Granulate the mixed material through a twin-screw extruder, and test the mechanical properties and flame retardant properties of the sample according to the method described above.

[0063] Composite Example 6 Nylon 6 100 parts, modified palygorskite-3# 1 part, antioxidant 0.2 parts.

[0064] (1) Take all raw materials by weight fraction, use a high-speed plastic mixer, control the speed at 800 r / min, and stir for 10 minutes at 80°C to make them fully mixed and uniform; (2) Granulate the mixed material through a twin-screw extruder, and test the mechanical properties and flame retardant properties of the sample according to the method described above.

[0065] Composite Comparative Example 1 Nylon 66 100 parts, unmodified palygorskite 1 part, antioxidant 0.2 parts.

[0066] (1) Take all raw materials by weight fraction, use a high-speed plastic mixer, control the speed at 800 r / min, and stir for 10 minutes at 80°C to make them fully mixed and uniform; (2) Granulate the mixed material through a twin-screw extruder, and test the mechanical properties and flame retardant properties of the sample according to the method described above.

[0067] Composite Comparative Example 2 Nylon 66 100 parts, antioxidant 0.2 parts.

[0068] (1) All raw materials are taken by weight parts, using a plastic high-speed stirrer, the speed is controlled at 800r / min, the temperature is 80℃, stirring for 10 minutes, so that it is fully mixed uniformly; (2) The mixed material is granulated by a double screw extruder, and the mechanical properties and flame retardant properties of the sample are tested according to the method described above The content described in the present application is not limited to the content described in the embodiments of the present application. The specific examples are applied herein to describe the structure and implementation of the present application, and the above embodiment description is only used to help understand the core idea of the present application. It should be pointed out that, for ordinary skilled in the art, without departing from the principles of the present application, the present application can be improved and modified, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0069] Finally, it should be pointed out that the above content is only used to explain the technical solutions of the present application, and is not a limitation on the protection scope of the present application. Simple modifications or equivalent replacements of the technical solutions of the present application by ordinary skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A process for the preparation of a halogen-free flame-retardant nylon nanocomposite material, characterized in that, The method comprises the following steps: S1: mixing nylon resin, antioxidant and modified palygorskite according to proportions to obtain a premix; S2: melt blending the premix through an extruder, extruding and granulating to obtain the halogen-free flame-retardant nylon nanocomposite; The halogen-free flame-retardant nylon nanocomposite comprises the following components by weight: 100 parts of nylon resin; 0.2 parts of antioxidant; and 0.5-10 parts of modified palygorskite; the modified palygorskite is palygorskite treated by surface modification with phytic acid and coupling agent.

2. The process for preparing halogen-free flame-retardant nylon nanocomposite according to claim 1, characterized in that, The modified palygorskite is 1-5 parts by weight.

3. The process for the preparation of halogen-free flame-retardant nylon nanocomposites according to claim 1 or 2, characterized in that, The nylon resin is one or more of nylon 6, nylon 66, nylon 6T, nylon 5T, PA9T, PA10T or MXD6.

4. A halogen-free flame-retardant nylon nanocomposite, characterized by, The method is prepared by any one of claims 1-3.

5. The process for preparing halogen-free flame-retardant nylon nanocomposite according to any one of claims 1 to 3, characterized in that, The modified palygorskite is prepared by the following method: a) soaking palygorskite in concentrated hydrochloric acid for 1-12 h, then washing to neutral with deionized water, and drying; b) grinding the palygorskite treated in step a) into powder; c) adding the palygorskite powder into water to prepare a suspension with a concentration of 1-20 wt%, and stirring at 60℃ for 2 h at high speed; d) adding phytic acid to the suspension of step c), wherein the ratio of phytic acid to ion exchange capacity of palygorskite is 0.5-5:1; e) preparing a silane coupling agent ethanol solution with a concentration of 1-20%; f) adding the coupling agent ethanol solution of step e) to the mixture of step d), heating to 80℃ and stirring for 4 h, wherein the amount of coupling agent added is 0.1-5% of the mass of palygorskite; g) centrifuging the solution obtained in step f), taking the solid, and washing with ethanol and deionized water in sequence; h) drying and crushing the washed solid to obtain the modified palygorskite.

6. The coupling agent according to claim 5, mainly silane coupling agent KH550 / KH560 / KH570, titanate coupling agent 105 / 102 / 311W, aluminate coupling agent 1618 / 181, etc. The coupling agent is one or a combination of several.

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