A flame-retardant nylon composition, and a preparation method and application thereof

Abstract

The application discloses a kind of flame-retardant nylon compositions and its preparation method and application, belong to engineering plastics field.The flame-retardant nylon composition described in the application includes the following weight parts of components: PA66 resin 10-35 parts, semi-aromatic polyamide resin 5-15 parts, organic phosphinic acid salt flame retardant and synergist 14-26 parts, glass fiber 18-52 parts, in-situ coating agent 0.8-5.3 parts;The in-situ coating agent is ethylene-alkyl acrylate-maleic anhydride copolymer;The semi-aromatic polyamide resin is selected from at least one of PA6I / 6T, MXD6.The flame-retardant nylon composition prepared by the interaction between components has excellent flame-retardant performance, is resistant to boiling, has good appearance, and is especially suitable for bright color product connectors.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering plastics, in particular to a flame-retardant nylon composition and a preparation method and application thereof. BACKGROUND

[0002] In recent years, the rapid development of new energy vehicles, photovoltaic energy storage and other industries has promoted the demand for new energy connectors. Among them, flame-retardant nylon materials are used as common materials for new energy connectors due to their balanced mechanical properties, excellent flame retardance and electrical properties. In the common nylon flame-retardant system, the organic phosphite salt flame-retardant system has been attracting more and more attention due to its high electrical properties, easy color matching and good mechanical properties; however, the flame-retardant efficiency of the organic phosphite salt is relatively low, and a large amount of flame retardant needs to be added to achieve a 0.8mm flame-retardant V-0 grade, and the synergistic effect of the synergistic agent is needed to meet the flame-retardant requirements; moreover, in actual production, in order to balance the product appearance and production efficiency, the molding die temperature cannot be too high, at this time, the material temperature or the injection speed needs to be increased, but too high material temperature and injection speed can easily cause the product to be discolored during injection molding, which limits the application of flame-retardant nylon materials in bright colors such as orange and red in new energy connectors.

[0003] CN104448801A discloses a halogen-free flame-retardant polyamide with high gloss and low warping and a preparation method thereof, which introduces maleic anhydride grafted polystyrene (PS) as a compatibilizer in the flame-retardant system, and uses a copolymer nylon as the resin matrix, so that the product has excellent appearance quality and a wide processing window; however, the technology adds an organic phosphite salt flame retardant, and the compatibility of the organic phosphite salt flame retardant with nylon is poor, so a high amount of the organic phosphite salt flame retardant needs to be added to achieve good flame-retardant properties, but too high an amount of the organic phosphite salt flame retardant leads to a significant decrease in the flowability of the system, poor injection molding appearance and serious surface fiber floating.

[0004] CN109553968A discloses a low-water-absorption good-appearance flame-retardant polyamide polymer and a preparation method thereof, which introduces toluene diisocyanate and polyketone in the system to improve the appearance of the organic phosphite salt flame-retardant polyamide by increasing the compatibility and dispersibility of the components; however, the technology introduces active isocyanate and a peroxide such as dicumyl peroxide (DCP), which can easily lead to rapid aging of the product and is not suitable for mass production; at the same time, in order to improve the toughness and dimensional stability of the product, the product usually needs to be treated by boiling after injection molding, the organic phosphite salt flame-retardant system is acidic by nature, and the color powder in bright colors such as orange and red is usually an organic pigment or dye, which can easily migrate during boiling treatment, thereby changing the color of the product; therefore, the existing polyamide materials suitable for bright color products usually cannot balance the water boiling resistance of the materials.

[0005] In view of the problems of the above flame-retardant nylon material, developing a flame-retardant nylon material with excellent flame-retardant performance, water boiling resistance, good appearance, and especially suitable for connectors of bright color products is the focus of the current research. SUMMARY

[0006] Based on the defects of the prior art, the purpose of the present application is to provide a flame-retardant nylon composition, its preparation method and application, which has excellent flame-retardant performance, water boiling resistance, good appearance, and is especially suitable for connectors of bright color products.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0008] A flame-retardant nylon composition, the flame-retardant nylon composition comprises the following components by weight: PA66 resin 10-35 parts, semi-aromatic polyamide resin 5-15 parts, organic phosphinate flame retardant and synergist 14-26 parts, glass fiber 18-52 parts, in-situ coating agent 0.8-5.3 parts.

[0009] The semi-aromatic polyamide resin is selected from at least one of PA6I / 6T and MXD6.

[0010] The product using organic phosphinate flame retardant in the prior art has poor appearance of the product prepared at the conventional injection molding temperature, and in order to improve the production efficiency and the appearance of the product, the prior art usually adopts the method of increasing the material temperature or the injection speed; however, too high material temperature and injection speed also easily cause discoloration of the product during injection molding, especially some bright colored products such as orange and red, since the color powder has poor temperature resistance, discoloration during injection molding is more likely to occur under the condition of too high material temperature and injection speed, which seriously affects the appearance of the product.

[0011] The inventors of the present application have found that by introducing a specific in-situ coating agent into the organic phosphinate flame retardant system, the in-situ coating agent has interaction with the phosphorus of the flame retardant, the organic phosphinate flame retardant is coated during product processing, the compatibility between the flame retardant and the polyamide resin matrix is improved, the flowability of the whole system is greatly improved, and even when the content of the flame retardant is high, the injection molding appearance will not decrease, and the problem of surface fiber floating of the product is solved.

[0012] The inventors have also found that the monomer composition of the in-situ coating agent has a great influence on its coating performance, the maleic anhydride grafted polyolefin-unsaturated alkyl ester polymer has better compatibility with the system than the glycidol grafted polyolefin-unsaturated alkyl ester polymer, has better coating effect, and can obtain better injection molding product appearance.

[0013] The application also finds that the amount of in-situ coating agent added has an influence on the mechanical properties of the final product. If the amount of in-situ coating agent added is too much, the tensile and bending strength of the final product is greatly reduced, and the flowability of the system is reduced, which is not conducive to the appearance of injection molding. If the amount of in-situ coating agent added is too little, the coating effect of the flame retardant is not good, resulting in poor appearance of the product injection molding.

[0014] Meanwhile, a semi-aromatic polyamide resin is introduced into the PA66 resin system, and the semi-aromatic polyamide resin is selected from at least one of PA6I / 6T and MXD6. The application finds through a large number of experiments that the semi-aromatic polyamide resin has good barrier properties, can delay the speed of moisture intrusion into the inside of the material during boiling treatment, thereby reducing the migration of toner and better improving the boiling discoloration of the bright color organic phosphite salt flame retardant system.

[0015] As a preferred embodiment of the flame-retardant nylon composition of the application, the in-situ coating agent is an ethylene-alkyl acrylate-maleic anhydride copolymer; wherein the weight percentage content of maleic anhydride is 0.2%-10%, and the weight percentage content of alkyl acrylate is 0-40%.

[0016] As a preferred embodiment of the flame-retardant nylon composition of the application, the melt flow rate of the in-situ coating agent is 0.5-200 g / 10 min under the condition of 190℃ and 2.16 kg weight measured according to ISO 1133-2011.

[0017] As a more preferred embodiment of the flame-retardant nylon composition of the application, the semi-aromatic polyamide resin is MXD6. The application finds through a large number of experiments that the semi-aromatic polyamide resin can make the boiling performance of the final product better under the preferred conditions.

[0018] As a preferred embodiment of the flame-retardant nylon composition of the application, the viscosity of the PA66 resin is 2.3-2.8 measured according to the ISO 307 standard; the test temperature is 25℃, the sample with a resin concentration of 0.005 g / mL is dissolved by using concentrated sulfuric acid with a concentration of 96%, and the Ubbelohde viscometer is used for measurement.

[0019] As a preferred embodiment of the flame-retardant nylon composition of the application, the viscosity of the semi-aromatic polyamide resin is 2.4-3.0 measured according to the ISO 307 standard; the test temperature is 25℃, the sample with a resin concentration of 0.005 g / mL is dissolved by using concentrated sulfuric acid with a concentration of 96%, and the Ubbelohde viscometer is used for measurement.

[0020] As a preferred embodiment of the flame-retardant nylon composition of the application, the end amino group content of the semi-aromatic polyamide is 30-50 mmol / kg.

[0021] As a preferred embodiment of the flame-retardant nylon composition of the present application, the glass fiber is alkali-free short-cut glass fiber, and the flat ratio is 1-5.

[0022] As a more preferred embodiment of the flame-retardant nylon composition of the present application, the flat ratio of the glass fiber is 3-4; the inventors have found through a large number of experiments that the short-cut glass fiber in the specific flat ratio range has better flowability, and can make the appearance performance of the final product better.

[0023] As a preferred embodiment of the flame-retardant nylon composition of the present application, the flat ratio of the glass fiber of the present application is calculated in the following manner:

[0024] The flat ratio = the length of the cross section of the glass fiber / the width.

[0025] As a preferred embodiment of the flame-retardant nylon composition of the present application, the short-cut length of the glass fiber is 2-4 mm, and the fiber diameter is 9-13 μm.

[0026] As a preferred embodiment of the flame-retardant nylon composition of the present application, the organic phosphinic acid salt flame retardant is an organic phosphinic acid salt and its derivatives; and the synergist is at least one of aluminum diethyl phosphinate, melamine derivatives, zinc salt.

[0027] As a more preferred embodiment of the flame-retardant nylon composition of the present application, the weight fraction of the melamine derivative is 1-3 parts, and the weight fraction of the zinc borate is 1-3 parts.

[0028] As a preferred embodiment of the flame-retardant nylon composition of the present application, the mass ratio of the organic phosphinic acid salt flame retardant and the synergist is 10-20:2-5.

[0029] As a preferred embodiment of the flame-retardant nylon composition of the present application, the components of the flame-retardant nylon composition further comprise 0.2-5 parts of a processing aid.

[0030] As a more preferred embodiment of the flame-retardant nylon composition of the present application, the processing aid comprises at least one of a lubricant and an antioxidant.

[0031] As a most preferred embodiment of the flame-retardant nylon composition of the present application, the lubricant is at least one of silicone, polyethylene wax, and ester lubricant; and / or, the antioxidant comprises at least one of hindered phenol antioxidant, hindered amine antioxidant, thioester antioxidant, and phosphite antioxidant.

[0032] As a preferred embodiment of the flame-retardant nylon composition of the present application, the content of the polyamide resin in the flame-retardant nylon composition of the present application is not less than 25 wt%.

[0033] Another object of the present application is to provide a preparation method of the flame-retardant nylon composition, comprising the following steps: uniformly mixing each component of the flame-retardant nylon composition, and then placing it into a twin-screw extruder for melting, extruding and granulating, so as to obtain the flame-retardant nylon composition.

[0034] As a preferred embodiment of the preparation method of the flame-retardant nylon composition of the present application, the length-diameter ratio of the twin-screw extruder is 36-48:1, the screw rotation speed is 300-500 rpm, and the extrusion temperature is 230-270℃.

[0035] After the flame-retardant nylon composition product of the present application is injection molded into an ISO sample bar, the mechanical properties are good according to the ISO527 standard, specifically: the tensile strength is above 120 MPa, the bending strength is above 200 MPa, and the Izod notched impact strength is above 11.5 MPa.

[0036] Still another object of the present application is to provide an application of the flame-retardant nylon composition in preparing a new energy charging pile connector component.

[0037] The present application has the following beneficial effects:

[0038] The present application provides a flame-retardant nylon composition, which has excellent flame-retardant properties, boiling resistance and good appearance through the interaction between each component, and is especially suitable for bright-colored product connectors. DETAILED DESCRIPTION

[0039] In order to better illustrate the objects, technical solutions and advantages of the present application, the present application will be further described below in combination with specific examples and comparative examples, the purpose of which is to understand the content of the present application in detail, rather than to limit the present application. All other examples obtained by those skilled in the art without creative labor fall within the protection scope of the present application. The experimental reagents and instruments involved in the implementation of the present application are all common ordinary reagents and instruments unless otherwise specified.

[0040] Among them, the processing aid is selected from antioxidants and lubricants, the antioxidant is a hindered phenolic antioxidant and a phosphite antioxidant, the mass ratio of the two is 2:3, and both are conventional commercially available products; the lubricant is an ester lubricant; in the present application, the mass ratio of the antioxidant to the lubricant is antioxidant: lubricant = 5:4.

[0041] In the components of each example and comparative example:

[0042] In-situ coating agent 1: 4700, ethylene-ethyl acrylate-maleic anhydride copolymer obtained by high pressure radical catalysis, weight ratio of ethylene: ethyl acrylate: maleic anhydride = 68.5:30:1.5, melt flow rate of 3-10 g / 10 min (test conditions of 190℃, 2.16 kg, ISO 1133-2011);

[0043] In-situ coating agent 2: 3410, ethylene-butyl acrylate-maleic anhydride copolymer obtained by high pressure radical catalysis, weight ratio of ethylene: butyl acrylate: maleic anhydride = 78:18:3, melt flow rate of 3-10 g / 10 min (test conditions of 190℃, 2.16 kg, ISO 1133-2011);

[0044] In-situ coating agent 3: ethylene-methyl acrylate-glycidyl methacrylate copolymer, LOTADER AX8900, Arkema;

[0045] Glass fiber 1: flat ratio of 3, chopped length of 3 mm, fiber diameter of 10 μm, ECS 3F-03-568H, Jushi Group;

[0046] Glass fiber 2: flat ratio of 3, chopped length of 3 mm, fiber diameter of 10 μm, Glass Fiber 301 HP-3-M3, Chongqing Glass Fiber;

[0047] Glass fiber 3: flat ratio of 1, chopped length of 3 mm, fiber diameter of 10 μm, Glass Fiber 301 HP-3-H, Chongqing Glass Fiber;

[0048] Glass fiber 4: flat ratio of 4, chopped length of 3 mm, fiber diameter of 10 μm, ECS 301-HP-3-M4, Chongqing Glass Fiber;

[0049] Glass fiber 5: flat ratio of 6, chopped length of 3 mm, fiber diameter of 10 μm, ECS 4F-03-534A, Jushi Group;

[0050] PA66, commercially available;

[0051] Semi-aromatic polyamide resin:

[0052] A1: PA6I / 6T, TI-1207, Shandong Guangyin New Material Co., Ltd.;

[0053] A2: MXD6, commercially available;

[0054] A3: PA66 / 6T, NPD-652, E. I. du Pont de Nemours and Company;

[0055] Organic phosphinic acid salt flame retardant: aluminum diethyl phosphinate, commercially available;

[0056] Synergist 1: Melamine polyphosphate, commercially available;

[0057] Synergist 2: Zinc borate, commercially available;

[0058] Processing aid:

[0059] Antioxidant: Antioxidant 1098 and Antioxidant PEP-36, mass ratio of 2:3, commercially available;

[0060] Lubricant: TR044W, commercially available.

[0061] Examples 1-9 and Comparative Examples 1-7

[0062] Examples 1-9 and Comparative Examples 1-7 are the flame-retardant nylon compositions of the present application; the components and weight parts of the flame-retardant nylon compositions of Examples 1-9 and Comparative Examples 1-7 are shown in Tables 1-3.

[0063] The preparation method of the flame-retardant nylon compositions of Examples 1-9 and Comparative Examples 1-7 comprises the following steps:

[0064] Mixing the components uniformly, and then placing them into a twin-screw extruder for melting, extruding and granulating, to obtain the flame-retardant nylon compositions.

[0065] The length-diameter ratio of the twin-screw extruder is 36-48:1, the screw rotation speed is 300-500 rpm, and the extrusion temperature is 230-270℃.

[0066] Table 1

[0067]

[0068]

[0069] Table 2

[0070]

[0071] Table 3

[0072]

[0073]

[0074] Effect example

[0075] In order to verify the performance of the products of the present application, the products of each example and comparative example are subjected to the following performance tests, and the specific steps are as follows:

[0076] (1) Appearance grade test: the products of the examples and the comparative examples were dried in an oven at 120℃ for 4h, then injection molded into common color plates with the size of 90x55x2mm, continuously injection molded, and the 11th-15th moldings were taken to visually evaluate the injection molding appearance grade; the appearance grade evaluation: grade 1 means that the surface appearance is good with no obvious floating fibers; grade 2 means that the appearance is good with only slight floating fibers in some parts; grade 3 means that the appearance is general with floating fibers in some parts; grade 4 means that the appearance is poor with more floating fibers on the surface; and grade 5 means that the appearance is very poor with very serious floating fibers on the surface;

[0077] (2) Flame retardant performance test: the products of the examples and the comparative examples were injection molded into UL flame retardant samples, and tested according to the UL94 standard;

[0078] (3) Water boiling performance test: the products of the examples and the comparative examples were injection molded into standard color plates, which were then boiled in water at 90℃ for 2h; the color L / a / b values were tested by using a color difference meter before and after boiling, and the color difference ΔE before and after boiling was calculated.

[0079] The test results are shown in Table 4.

[0080] Table 4

[0081]

[0082]

[0083] As can be seen from Table 4, when the technical solution of the present application is adopted, the obtained flame retardant nylon composition has excellent flame retardant property, the flame retardant thickness reaches 0.8mm, the water boiling discoloration resistance is excellent with ΔE less than 6 before and after boiling; and the appearance of the prepared product is good with the appearance grade being grade 3 or above.

[0084] As can be seen by comparing Comparative Examples 1-2 and Comparative Example 1, the selection of the specific in-situ coating agent of the present application can obviously affect the appearance performance of the product; when the in-situ coating agent is a maleic anhydride grafted polyolefin-unsaturated alkyl ester polymer, the appearance performance and flame retardant performance of the obtained product are more excellent.

[0085] As can be seen by comparing Comparative Example 1 and Comparative Examples 2 and 3, when the weight fraction of the in-situ coating agent is not within the range provided by the present application, it will affect the comprehensive performance of the product; the weight fraction of the in-situ coating agent in Comparative Examples 2 and 3 is too small or too large; the coating agent in Comparative Example 2 is too small, the effect of coating the flame retardant agent is not good, and the appearance is poor; the coating agent in Comparative Example 3 is too large, the flame retardant performance of the product is decreased, and the appearance grade is decreased.

[0086] As can be seen by comparing Comparative Example 1 and Comparative Examples 4-7, when the flat ratio of the glass fiber is within the range provided by the present application, the comprehensive performance of the obtained product is more excellent.

[0087] Finally, it should be noted that the above examples are merely intended to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A flame-retardant nylon composition, characterized in that, The flame-retardant nylon composition comprises the following components in parts by weight: 10-35 parts of PA66 resin, 5-15 parts of semi-aromatic polyamide resin, 14-26 parts of organic phosphonate flame retardant and synergist, 18-52 parts of glass fiber, and 0.8-5 parts of in-situ coating agent. The in-situ coating agent is an ethylene-alkyl acrylate-maleic anhydride copolymer, wherein the weight percentage of maleic anhydride is 0.2%-10%, the weight percentage of alkyl acrylate is 0-40%, and the weight of alkyl acrylate is not 0. The semi-aromatic polyamide resin is selected from at least one of PA6I / 6T and MXD6; The organic hypophosphite flame retardant is an organic hypophosphite; the synergist is melamine polyphosphate and zinc borate; The melamine polyphosphate is present in 1-3 parts by weight, and the zinc borate is present in 1-3 parts by weight. The mass ratio of the organic phosphonate flame retardant to the synergist is 10-20:2-5.

2. The flame-retardant nylon composition as described in claim 1, characterized in that, The semi-aromatic polyamide resin is MXD6.

3. The flame-retardant nylon composition as described in claim 1, characterized in that, The glass fiber is alkali-free chopped glass fiber with an aspect ratio of 1-5.

4. The flame-retardant nylon composition as described in claim 1, characterized in that, The glass fiber has a chopped length of 2-4 mm and a fiber diameter of 9-13 μm.

5. The flame-retardant nylon composition as claimed in claim 1, characterized in that, The flame-retardant nylon composition also includes 0.2-5 parts of processing aids.

6. The flame-retardant nylon composition as described in claim 5, characterized in that, The processing aid is selected from at least one of lubricants and antioxidants.

7. The method for preparing the flame-retardant nylon composition according to any one of claims 1-6, characterized in that, Includes the following steps: The components of the flame-retardant nylon composition are mixed evenly, and then placed in a twin-screw extruder for melting, extrusion, and granulation to obtain the flame-retardant nylon composition.

8. The application of the flame-retardant nylon composition according to any one of claims 1-6 in the preparation of connector components for new energy charging piles.

Images