Polyamide composite material as well as preparation method and application thereof

Abstract

The invention provides a polyamide composite material as well as a preparation method and application thereof, and the polyamide composite material comprises the following components in parts by weight: 30-60 parts of polyamide 66 resin, 10-30 parts of high char-forming resin, 4.5-8.5 parts of a red phosphorus flame retardant, 1-4 parts of a melamine derivative and 20-50 parts of glass fiber. The high char forming resin comprises aromatic polyamide; a molecular chain of the aromatic polyamide contains an aromatic diamine structural unit. According to the polyamide composite material disclosed by the invention, the oxygen index of the material can be improved by compounding specific types of high-char-forming resin, red phosphorus flame retardant and melamine derivative, meanwhile, the mechanical property and flame retardant property of the material are both considered, the properties are relatively balanced, and the polyamide composite material has the characteristics of no halogen, high performance, stable flame retardance and easiness in processing; the high requirement on the oxygen index of the material in the field of rail transit can be met.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering plastics, and specifically relates to a polyamide composite material and a preparation method and application thereof. Background Art

[0002] Rail vehicles are in a relatively closed space and are crowded with people. Once a fire occurs, escape and rescue are difficult. For the fire test standards of rail vehicle materials, the test standards and methods of each country are different. Among them, the EU EN45545-2 divides the fire hazard level into three levels: HL1, HL2 and HL3, and the requirements for the flame retardant properties of the materials are also different. EN45545-2 R22&R23 HL2 level requires the material's oxygen index to be above 28, and HL3 level requires the oxygen index to be above 32. Red phosphorus flame retardant nylon material is widely used in the field of rail vehicles due to its good molding performance and appearance, high relative tracking index, high mechanical properties and low heat deformation temperature, and halogen-free. , Especially for low-voltage electrical appliances, switches, connectors, etc.

[0003] However, conventional red phosphorus flame retardant materials are mainly based on condensed phase flame retardancy, with less gas phase flame retardancy. In condensed phase flame retardancy, the dehydration and carbonization of oxygen-containing phosphoric acid is the main effect, which plays a role in flame retardant oxygen and combustibles to achieve the flame retardant effect. Therefore, compared with phosphorus-nitrogen flame retardant, its carbonization effect is weaker, and compared with nitrogen flame retardant, its product capacity is insufficient, which makes the oxygen index of red phosphorus flame retardant materials low, generally below 28, and it is difficult to meet the HL2 grade requirement of more than 28. For example, BASF's classic red phosphorus flame retardant nylon materials A3X2G5, A3X2G7 and other brands, their oxygen index is only between 26-27. The low oxygen index of red phosphorus flame retardant nylon materials seriously limits their application in the field of rail transportation.

[0004] Patent CN110564147A discloses a high oxygen index red phosphorus flame retardant reinforced nylon 66 composite. By adding organic nano-montmorillonite or a mixture of melamine cyanurate salt and organic nano-montmorillonite, the oxygen index of the red phosphorus flame retardant material can be increased to above 28. However, montmorillonite will reduce the mechanical properties of the material, and the oxygen index of the composite material is still low.

[0005] Therefore, developing a red phosphorus flame retardant polyamide material with a high oxygen index and without reducing the mechanical properties of the material is an urgent problem to be solved in this field. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a polyamide composite material and a preparation method and application thereof. The polyamide composite material has both high oxygen index and good mechanical properties, and has no halogen in the system, is environmentally friendly, easy to process, and can meet the high requirements for material oxygen index in the field of rail transportation.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a polyamide composite material, which comprises, by weight, 30 to 60 parts of polyamide 66 resin, 10 to 30 parts of high carbonization resin, 4.5 to 8.5 parts of red phosphorus flame retardant, 1 to 4 parts of melamine derivatives and 20 to 50 parts of glass fiber; the high carbonization resin comprises aromatic polyamide; and the molecular chain of the aromatic polyamide contains aromatic diamine structural units.

[0009] In the present invention, red phosphorus produces oxygen-containing phosphoric acid during combustion, which covers the surface of the material and has the effect of dehydration and carbonization, thereby flame retardant oxygen and combustibles. During combustion of aromatic polyamide containing aromatic diamine structural units, the aromatic diamine can interact with the oxygen-containing phosphoric acid to achieve synergistic effect, and the presence of the benzene ring improves the carbonization effect of the entire system, thereby improving the carbonization efficiency of the system. Melamine derivatives are easily decomposed to produce inert gases when heated, which dilutes the concentration of combustibles, and at the same time plays a synergistic role of NP in the condensed phase, further improving the oxygen index of the system. By compounding a specific type of high-carbonization resin, red phosphorus flame retardant and melamine derivatives, the oxygen index of the material can be improved, and the mechanical properties and flame retardant properties of the material can be taken into account, the performance is relatively balanced, and the material has the characteristics of halogen-free, high performance, flame retardant stability, and easy processing, which can meet the high requirements for oxygen index in the field of rail transit.

[0010] In the present invention, 30 to 60 parts of polyamide 66 resin can be, for example, 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts or a range consisting of any of the above values; preferably 35 to 55 parts, more preferably 40 to 50 parts.

[0011] In the present invention, 10 to 30 parts of high carbon forming resin can be, for example, 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, 12.5 parts, 13 parts, 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 18.5 parts, 19 parts, 19.5 parts, 20 parts, 20.5 parts, 21 parts, 21.5 parts, 22 parts, 22.5 parts, 23.5 parts, 24 parts, 24.5 parts, 25 parts, 25.5 parts, 26 parts, 26.5 parts, 27 parts, 27.5 parts, 28 parts, 28.5 parts, 29 parts, 29.5 parts, 30 parts or the range composed of any of the above values; preferably 11 to 25 parts, more preferably 13 to 20 parts.

[0012] In the present invention, 4.5 to 8.5 parts of red phosphorus flame retardant can be, for example, 4.5 parts, 4.6 parts, 4.8 parts, 5 parts, 5.2 parts, 5.4 parts, 5.6 parts, 5.8 parts, 6 parts, 6.2 parts, 6.4 parts, 6.6 parts, 6.8 parts, 7 parts, 7.2 parts, 7.4 parts, 7.6 parts, 7.8 parts, 8 parts, 8.2 parts, 8.4 parts, 8.5 parts or the range composed of any of the above values; preferably 5 to 8 parts, more preferably 5.5 to 7.5 parts.

[0013] In the present invention, 1 to 4 parts of melamine derivatives can be, for example, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2 parts, 2.1 parts, 2.2 parts, 2.3 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.7 parts, 2.8 parts, 2.9 parts, 3 parts, 3.1 parts, 3.2 parts, 3.3 parts, 3.4 parts, 3.5 parts, 3.6 parts, 3.7 parts, 3.8 parts, 3.9 parts, 4 parts or a range consisting of any of the above values; preferably 1.5 to 3.5 parts.

[0014] In the present invention, 20 to 50 parts of glass fiber can be, for example, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts or a range consisting of any of the above values; preferably 22 to 45 parts.

[0015] In the present invention, the relative viscosity of the polyamide 66 resin is 2 to 3.5, for example, it can be 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5 or any range between the above values; more preferably, the relative viscosity is 2.5 to 3.

[0016] In the present invention, the relative viscosity of the high carbon-forming resin is 2 to 3, for example, it can be 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3 or any range between the above values; more preferably, the relative viscosity is 2.1 to 2.8.

[0017] In the present invention, the relative viscosity of the polyamide 66 resin or high carbon-forming resin is measured in 96% concentrated sulfuric acid at 25±0.01° C. according to the standard GB / T12006.1-2009, and the test concentration is 1 g / dL.

[0018] Preferably, the aromatic polyamide comprises semi-aromatic polyamide.

[0019] Preferably, the semi-aromatic polyamide comprises poly(meta-xylylene adipamide) and / or poly(meta-xylylene sebacate).

[0020] Preferably, the semi-aromatic polyamide comprises poly(meta-xylylene adipamide) and poly(meta-xylylene sebacamide), and the mass ratio of poly(meta-xylylene adipamide) to poly(meta-xylylene sebacamide) is 1:(0.5-4.5), wherein the specific value in (0.5-4.5) can be, for example, 0.5, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.5 or a range consisting of any of the above values, more preferably 1:(1.2-3.2).

[0021] Preferably, the red phosphorus flame retardant includes red phosphorus and / or red phosphorus masterbatch.

[0022] Preferably, the red phosphorus masterbatch comprises polyamide resin encapsulated red phosphorus.

[0023] Preferably, the mass percentage of red phosphorus in the red phosphorus masterbatch is 35-55%, for example, it can be a range consisting of any of the above values: 35%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, or 55%.

[0024] In the present invention, the polyamide resin in the red phosphorus flame retardant includes polycaprolactam resin (PA6).

[0025] Preferably, the melamine derivative comprises at least one of melamine cyanurate, melamine polyphosphate or melamine borate.

[0026] Preferably, the melamine derivative comprises melamine cyanurate and melamine polyphosphate, and the mass ratio of melamine cyanurate to melamine polyphosphate is 1:(0.5-2.5), wherein the specific value in (0.5-2.5) can be, for example, 0.5, 0.52, 0.55, 0.58, 0.6, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5 or a range consisting of any of the above values, more preferably 1:(1-2).

[0027] Preferably, the glass fibers include alkali-free chopped glass fibers.

[0028] Preferably, the chopped length of the glass fiber is 3 to 4.5 mm, for example, it can be 3 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 4 mm, 4.1 mm, 4.2 mm, 4.3 mm, 4.4 mm, 4.5 mm or a range consisting of any of the above values; the fiber diameter is 9 to 13 μm, for example, it can be 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm or a range consisting of any of the above values.

[0029] Preferably, the polyamide composite material further comprises 0.2 to 5 parts of other additives by weight, for example, 0.2, 0.4, 0.6, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or any range thereof.

[0030] Preferably, the other auxiliary agents include antioxidants and / or lubricants.

[0031] Preferably, the other additives include 0.1 to 2 parts of lubricant and 0.1 to 3 parts of antioxidant.

[0032] Preferably, the antioxidant comprises at least one of hindered phenol antioxidants, hindered amine antioxidants, thioester antioxidants or phosphite antioxidants, and more preferably is a composite system of hindered phenol antioxidants and phosphite antioxidants.

[0033] Preferably, the lubricant comprises at least one of silicone, polyethylene wax or pentaerythritol ester.

[0034] Preferably, the oxygen index of the polyamide composite material is ≥30, more preferably ≥35.

[0035] In a second aspect, the present invention provides a method for preparing the polyamide composite material according to the first aspect, the preparation method comprising the following steps:

[0036] The polyamide composite material is obtained by mixing polyamide 66 resin, high carbonization resin, red phosphorus flame retardant, melamine derivative and glass fiber and extruding them.

[0037] Preferably, the mixed material further comprises other auxiliary agents.

[0038] Preferably, the extrusion temperature is 230-270°C, for example, 230°C, 240°C, 250°C, 260°C, 270°C or any range thereof.

[0039] In the present invention, the extrusion is carried out in a twin-screw extruder, the aspect ratio of the twin-screw extruder is 36-48:1, and the screw speed is 300-500 rpm.

[0040] In the present invention, the mixing includes premixing polyamide 66 resin, high carbonization resin, lubricant and antioxidant in a high mixer for 1 to 3 minutes, then adding flame retardant, melamine derivative and glass fiber from a side feed port, mixing evenly, and adding to a twin-screw extruder through a metering scale for extrusion.

[0041] In a third aspect, the present invention provides a low-voltage electrical device, wherein the material of the low-voltage electrical device includes the polyamide composite material described in the first aspect.

[0042] In the present invention, the low-voltage electrical equipment includes low-voltage electrical appliances, switches, connectors, etc., and is particularly suitable for low-voltage electrical equipment in the field of rail transit.

[0043] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The polyamide composite material provided by the present invention can have a high oxygen index and good mechanical properties by compounding a specific type of high-carbon resin, a melamine derivative and a red phosphorus flame retardant, and can meet the high requirements for high oxygen index of materials in the field of rail transportation. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0047] The materials used in the present invention are all commercially available.

[0048] PA66: EPR27, Shenma Group;

[0049] Poly(m-xylylene adipamide): PAMXD6, Shanghai Yinggu Chemical;

[0050] Poly(m-phenylenediamine sebacate): PA MXD10, Shanghai Yinggu Chemical;

[0051] Poly(hexamethylene terephthalamide): PA6T, A3000, Mitsui Chemicals, Japan;

[0052] Polypentamethylene adipamide: PA56, PA56 Ecopent-1273, Cathay Biotechnology;

[0053] Red phosphorus flame retardant: microencapsulated red phosphorus masterbatch with polylactam resin (PA6) as carrier, the mass percentage of red phosphorus in the masterbatch is 50%, FR9950KF, Tongcheng Xinde New Materials;

[0054] Melamine polyphosphate: BUDIT 3141, BUDENHEIM IBERICA, SLU;

[0055] Melamine cyanurate: Nitrogen flame retardant lubricant MCA, Sichuan Fine Chemical Research and Design Institute;

[0056] Melamine borate: MB, Zhuoan Technology;

[0057] Glass fiber: Glass fiber ECS10-03-568H, Jushi Group;

[0058] Antioxidant: a composite antioxidant composed of N,N′-1,6-hexamethylene-bis-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (IRGANOX 1098) and bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate (PEP-36) in a mass ratio of 1:1.5;

[0059] Lubricant: TR044W, STRUKTOL Co.

[0060] Examples 1 to 14, Comparative Examples 1 to 9

[0061] Examples 1 to 14 and Comparative Examples 1 to 9 respectively provide a polyamide composite material, and the formulas of the polyamide composite materials are shown in Tables 1 to 4, in which “ / ” indicates that the component is not included in the formula, and the content of the red phosphorus flame retardant is the actual content of red phosphorus in the masterbatch.

[0062] The preparation method of the polyamide composite material comprises:

[0063] After mixing polyamide 66 resin, high carbonization resin, lubricant and antioxidant in a high mixer for 2 minutes, the mixture is added to the main feeding port of a twin-screw extruder, and red phosphorus flame retardant, melamine derivative and glass fiber are added from the side feeding port, and the mixed materials are respectively added to the twin-screw extruder through a metering scale for extrusion granulation to obtain the polyamide composite material. The twin-screw extruder has an aspect ratio of 48:1, a screw speed of 400 rpm, and an extrusion temperature of zones 6 to 10 of 230°C.

[0064] Table 1

[0065]

[0066] Table 2

[0067]

[0068]

[0069] Table 3

[0070]

[0071] Table 4

[0072]

[0073] Performance Testing

[0074] After the polyamide composite materials provided in Examples 1 to 14 and Comparative Examples 1 to 9 were dried in an oven at 120°C for 4 hours, ISO mechanical and UL flame retardant specimens were injection molded to evaluate the mechanical properties and flame retardant properties of the materials. ISO heat deformation specimens were injection molded, machined and ground to the required thickness, and the oxygen index of the materials was tested.

[0075] Among them, the flame retardant performance refers to the UL94 vertical burning test standard, and the material thickness is 1.6mm. The tensile strength test is carried out in accordance with ISO 527-2-2012, the bending strength test is carried out in accordance with ISO 178-2010, the Izod notched impact strength is tested in accordance with ISO 180-2019, and the oxygen index test is carried out in accordance with ISO 4589-2:2017, and the specimen thickness is 4mm.

[0076] The specific test results are shown in Table 5.

[0077] Table 5

[0078]

[0079] As shown in Table 5, the polyamide composite material provided by the present invention can have a high oxygen index, a low smoke density and good mechanical properties by compounding a specific type of high carbonization resin, a melamine derivative and a red phosphorus flame retardant, and the flame retardant grade meets the requirements; the oxygen index of the polyamide composite material is ≥30, the smoke density is ≤150, and the cantilever beam notched impact strength is ≥6.2 kJ / m 2 , tensile strength ≥ 138MPa, flexural strength ≥ 205MPa, more preferably the polyamide composite material has an oxygen index ≥ 35, a smoke density ≤ 100, and an Izod notched impact strength ≥ 7.0kJ / m 2 , tensile strength ≥143MPa, flexural strength ≥213MPa.

[0080] Comparison of Example 1 with Comparative Examples 1, 2 and 9 shows that the oxygen index has no obvious improvement effect when the high carbonization resin, melamine derivative and red phosphorus flame retardant are not compounded with a specific type.

[0081] It can be seen from the comparison between Example 1 and Comparative Examples 3 to 6 that the content of the high carbon-forming resin or melamine derivative is not within the specified range, the oxygen index is reduced or the mechanical properties are deteriorated.

[0082] It can be seen from the comparison between Example 1 and Comparative Examples 7 to 8 that the formula lacks high carbonization resin or melamine derivatives, and the oxygen index is reduced.

[0083] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A polyamide composite material, characterized in that: The polyamide composite material comprises, by weight, 30 to 60 parts of polyamide 66 resin, 10 to 30 parts of high carbonization resin, 4.5 to 8.5 parts of red phosphorus flame retardant, 1 to 4 parts of melamine derivative and 20 to 50 parts of glass fiber; The high carbon-forming resin includes aromatic polyamide; The molecular chain of the aromatic polyamide contains aromatic diamine structural units.

2. The polyamide composite material according to claim 1, characterized in that: The aromatic polyamide includes semi-aromatic polyamide.

3. The polyamide composite material according to claim 2, characterized in that: The semi-aromatic polyamide includes poly(meta-xylylene adipamide) and / or poly(meta-xylylene sebacate); Preferably, the semi-aromatic polyamide comprises poly(meta-xylylene adipamide) and poly(meta-xylylene sebacate), and the mass ratio of poly(meta-xylylene adipamide) to poly(meta-xylylene sebacate) is 1:(0.5-4.5), more preferably 1:(1.2-3.2).

4. The polyamide composite material according to any one of claims 1 to 3, characterized in that: The red phosphorus flame retardant includes red phosphorus and / or red phosphorus masterbatch; Preferably, the red phosphorus masterbatch comprises polyamide resin encapsulated red phosphorus; Preferably, the mass percentage of red phosphorus in the red phosphorus masterbatch is 35-55%.

5. The polyamide composite material according to any one of claims 1 to 4, characterized in that: The melamine derivative comprises at least one of melamine cyanurate, melamine polyphosphate or melamine borate; Preferably, the melamine derivative comprises melamine cyanurate and melamine polyphosphate, and the mass ratio of melamine cyanurate to melamine polyphosphate is 1:(0.5-2.5), and more preferably 1:(1-2); Preferably, the glass fibers include alkali-free chopped glass fibers; Preferably, the chopped length of the glass fiber is 3 to 4.5 mm, and the fiber diameter is 9 to 13 μm.

6. The polyamide composite material according to any one of claims 1 to 5, characterized in that: The polyamide composite material further comprises 0.2 to 5 parts by weight of other additives; Preferably, the other auxiliary agents include antioxidants and / or lubricants; Preferably, the antioxidant comprises at least one of a hindered phenol antioxidant, a hindered amine antioxidant, a thioester antioxidant or a phosphite antioxidant, and more preferably a composite system of a hindered phenol antioxidant and a phosphite antioxidant; Preferably, the lubricant comprises at least one of silicone, polyethylene wax or pentaerythritol ester.

7. The polyamide composite material according to any one of claims 1 to 6, characterized in that: The oxygen index of the polyamide composite material is ≥30.

8. A method for preparing a polyamide composite material according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: The polyamide composite material is obtained by mixing polyamide 66 resin, high carbonization resin, red phosphorus flame retardant, melamine derivative and glass fiber and extruding them.

9. The preparation method according to claim 8, characterized in that: The mixed material also includes other additives; Preferably, the extrusion temperature is 230-270°C.

10. A low voltage electrical equipment, characterized in that: The material of the low-voltage electrical equipment comprises the polyamide composite material according to any one of claims 1 to 7.

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