A flame-retardant nylon 6 composition and its preparation method

Abstract

This invention discloses a flame-retardant nylon 6 composition and its preparation method, relating to the field of polymer materials technology. The flame-retardant nylon 6 composition comprises the following components in parts by weight: 500-600 parts nylon 6, 30-50 parts polyimide, 30-150 parts intumescent flame retardant, 0-30 parts hyperbranched polyamide, and 1-10 parts antioxidant. The components are mixed evenly according to the specified proportions, placed in a twin-screw extruder, melt-extruded, and then granulated to obtain the flame-retardant nylon 6 composition. The twin-screw extruder has the following temperatures: Zone 1: 130-180℃; Zone 2: 220-240℃; Zone 3: 230-250℃; Zone 4: 235-255℃; Zone 5: 240-260℃; Zone 6: 250-265℃; and the die head temperature: 250-265℃. The product of this invention can be widely used in fields such as new energy batteries, cable ties, auto parts, electronic products, photovoltaic products, electrical engineering and home appliances.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a flame-retardant nylon 6 composition, its preparation method, and its application. Background Technology

[0002] Nylon 6 is a polymer, chemically known as polycaprolactam. Its molecular structure contains six carbon atoms, hence the name Nylon 6. Nylon 6 possesses high strength, heat resistance, abrasion resistance, and corrosion resistance, and also exhibits good self-lubricating properties, electrical insulation, and UV resistance. Furthermore, Nylon 6 has a high water absorption rate, but this does not cause significant dimensional changes. Due to these advantages, Nylon 6 is widely used in the automotive, electronics, textile, and aerospace industries.

[0003] However, Nylon 6's flame retardant properties are poor, requiring significant improvement. Traditional flame retardants for nylon (PA) are a blend of halogenated flame retardants and antimony trioxide, but with increasing environmental awareness, halogenated flame retardants are gradually being replaced. While red phosphorus flame-retardant nylon 6 masterbatch offers good flame retardancy and has minimal impact on the physical and electrical properties of the base resin, PA products containing red phosphorus flame retardants often suffer from color defects, typically preventing the production of light-colored products. Ordinary inorganic flame retardants, due to their high addition amounts, severely affect the mechanical properties of the material. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to overcome the shortcomings of the prior art and provide a flame-retardant nylon 6 composition, its preparation method and application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a flame-retardant nylon 6 composition, comprising the following components in parts by weight: 500-600 parts of nylon 6, 30-50 parts of polyimide, 30-150 parts of intumescent flame retardant, 0-30 parts of hyperbranched polyamide, and 1-10 parts of antioxidant.

[0006] Preferably, the melt index of the nylon 6, according to ASTM D1238-2010, is 1-10 g / 10 min under test conditions of 235°C and 2.16 kg load. At higher melting temperatures, nylon 6 with a lower melt index can better plasticize with polyimide and intumescent flame retardants, which is more conducive to improving mechanical properties and flame retardant properties.

[0007] Preferably, the polyimide is an ultrafine powder with a mesh size of not less than 400 mesh. The core of the polyimide's chemical structure—the imide bond—endows it with extremely high thermal and chemical stability, enabling it to maintain excellent performance even in extreme environments. Ultrafine-sized polyimide can be more uniformly dispersed in the polyamide. In this invention, during material combustion in the presence of an intumescent flame retardant, the polyimide can rapidly promote the formation of a nylon 6 char layer, increasing the thickness and density of the char layer, effectively improving the system's robustness and flame retardant efficiency.

[0008] Preferably, the hyperbranched polyamide has a molecular weight of 500-3000. The amino-terminated hyperbranched polyamide exhibits high reactivity and a highly branched three-dimensional network structure. During melting, it can physically entangle with nylon molecular chains and polyimide surface groups, creating connection points between the molecular chains to form a larger three-dimensional network structure. Furthermore, the amino functional groups react with active sites such as carboxyl groups in the composition during the reaction, forming new chemical bonds and creating a three-dimensional cross-linked network structure. When used in appropriate amounts, the amino-terminated hyperbranched polyamide can enhance the mechanical and flame-retardant properties of the nylon 6 composition; however, excessive amounts can lead to a significant decrease in the toughness of the composition.

[0009] Preferably, the intumescent flame retardant contains an acid source, a carbon source, and a gas source.

[0010] Preferably, the acid source is at least one selected from phosphoric acid, boric acid, sulfuric acid, and phosphate esters.

[0011] More preferably, the acid source is at least one of triphenyl phosphate and ammonium polyphosphate.

[0012] Preferably, the carbon source is at least one selected from starch, sucrose, dextrin, pentaerythritol, ethylene glycol, and phenolic resin.

[0013] Preferably, the gas source is at least one of urea and melamine.

[0014] Intumescent flame retardant (IFR) is an environmentally friendly green flame retardant that is halogen-free and does not use antimony oxide as a synergist; its system itself has a synergistic effect. Plastics containing IFR generate a charred foam layer on their surface during combustion, providing insulation, oxygen barrier, smoke suppression, and anti-drip properties, while producing low smoke, low toxicity, and no corrosive gases. In this invention, the IFR maximizes the assistance in the rapid charring of polyimide and nylon 6 surfaces, forming a charred foam layer.

[0015] Preferably, the antioxidant is at least one of hindered amines, hindered phenols, thiolated antioxidants, and phosphite antioxidants.

[0016] More preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 1098, antioxidant 1076, antioxidant 300, and antioxidant 168.

[0017] Furthermore, the present invention provides a method for preparing the flame-retardant nylon 6 composition, comprising the following steps:

[0018] (1) Mix 500-600 parts of nylon 6, 30-50 parts of polyimide, 30-150 parts of intumescent flame retardant, 0-30 parts of hyperbranched polyamide, and 1-10 parts of antioxidant evenly.

[0019] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0020] Preferably, the temperature of the twin-screw extruder is 130-180℃ in zone one, 220-240℃ in zone two, 230-250℃ in zone three, 235-255℃ in zone four, 240-260℃ in zone five, 250-265℃ in zone six, and 250-265℃ at the die head.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. The polyimide in the composition of the present invention can increase the thickness of the char layer formed by nylon 6, thereby improving the mechanical properties and flame retardant properties of the nylon 6 composition.

[0023] 2. In the composition of the present invention, the terminal amino hyperbranched polyamide can physically entangle with the nylon molecular chain and the surface groups of the polyimide, so that the molecular chains form connection points and form a larger three-dimensional network structure; the terminal amino hyperbranched polyamide can further enhance the mechanical properties and flame retardant properties of the nylon 6 composition.

[0024] 3. Through numerous experiments, it was found that, compared with other flame retardants, the intumescent flame retardant performs the best in the composition system of the present invention.

[0025] 4. The product of this invention can be widely used in new energy batteries, cable ties, electronic products, auto parts, electrical engineering, photovoltaic products and home appliances. Detailed Implementation

[0026] Unless otherwise specified, all raw materials used in this invention are commercially available or prepared according to conventional methods in the art. Unless otherwise defined or stated, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. Other aspects of this invention will be apparent to those skilled in the art from the disclosure herein. The invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0027] Unless otherwise specified, experimental methods in the following examples are generally performed according to national standards. If no corresponding national standard exists, general international standards, standard conditions, or conditions recommended by the manufacturer are followed. Unless otherwise stated, all parts are parts by weight, and all percentages are weight percentages.

[0028] It should be noted that those skilled in the art can make various changes and improvements without departing from the concept of this invention. These all fall within the scope of protection of this invention.

[0029] In the following examples and comparative examples, some raw material specifications and sources are described, but not limited to these materials:

[0030] Nylon 6-1: Grade 1013B, melt index 2.7g / 10min (235℃, 2.16kg), Ube Industries, Japan.

[0031] Nylon 6-2: Grade B3S, melt flow index 35g / 10min (235℃, 2.16kg), BASF, Germany. Polyimide Resin 1: Grade TT-100, 800 mesh ultrafine powder, Dongguan Taotao Plastic Raw Materials Co., Ltd. Polyimide Resin 2: Grade TT-100, 1000 mesh ultrafine powder, Dongguan Taotao Plastic Raw Materials Co., Ltd.

[0032] Amino-terminated hyperbranched polyamide 1: molecular weight 600, Wuhan Kemic Biomedical Technology Co., Ltd.

[0033] Amino-terminated hyperbranched polyamide 2: molecular weight 1000, Wuhan Kemic Biomedical Technology Co., Ltd.

[0034] Amino-terminated hyperbranched polyamide 3: molecular weight 2000, Wuhan Kemic Biomedical Technology Co., Ltd.

[0035] Intumescent flame retardant 1: Ammonium polyphosphate: Melamine: Pentaerythritol (weight ratio) is 10:5:7.

[0036] Intumescent flame retardant 2: Melamine: Pentaerythritol: Triphenyl phosphate (weight ratio) is 8:2:1.

[0037] Melamine: Powder form, Shandong Jinhongshun Chemical Co., Ltd.

[0038] Pentaerythritol: Sigma-Aldrich (Shanghai).

[0039] Ammonium polyphosphate: Jinan Xinnuo Chemical Co., Ltd.

[0040] Triphenyl phosphate: Jinan Yuyi Chemical Co., Ltd.

[0041] Melamine cyanurate (MCA): Dongguan Hongtaiji Flame Retardant Materials Co., Ltd.

[0042] Antioxidant: A mixture of antioxidant 1098 and antioxidant 168 in a 1:1 mass ratio, manufactured by DuPont, USA.

[0043] Example 1

[0044] (1) Mix 500 parts nylon 6-1, 30 parts polyimide 1, 35 parts intumescent flame retardant 1, and 1 part antioxidant evenly.

[0045] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0046] The twin-screw extruder has the following temperature zones: Zone 1: 130℃; Zone 2: 220℃; Zone 3: 230℃; Zone 4: 235℃; Zone 5: 240℃; Zone 6: 250℃; and the die head temperature: 250℃.

[0047] Example 2

[0048] (1) Mix 600 parts of nylon 6-1, 50 parts of polyimide 1, 150 parts of intumescent flame retardant 2, 28 parts of hyperbranched polyamide 1, and 8 parts of antioxidant evenly.

[0049] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0050] The temperature of the twin-screw extruder is 160℃ in zone 1, 240℃ in zone 2, 250℃ in zone 3, 255℃ in zone 4, 260℃ in zone 5, 265℃ in zone 6, and 265℃ at the die head.

[0051] Example 3

[0052] (1) Mix 520 parts of nylon 6-1, 45 parts of polyimide 1, 120 parts of intumescent flame retardant 1, 20 parts of hyperbranched polyamide 1, and 4 parts of antioxidant evenly.

[0053] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0054] The twin-screw extruder has the following temperature zones: Zone 1: 150℃; Zone 2: 240℃; Zone 3: 250℃; Zone 4: 255℃; Zone 5: 260℃; Zone 6: 265℃; and the die head temperature: 265℃.

[0055] Example 4

[0056] (1) Mix 520 parts of nylon 6-2, 45 parts of polyimide 1, 120 parts of intumescent flame retardant 1, 20 parts of hyperbranched polyamide 1, and 4 parts of antioxidant evenly.

[0057] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0058] The twin-screw extruder has the following temperature zones: Zone 1: 150℃; Zone 2: 240℃; Zone 3: 250℃; Zone 4: 255℃; Zone 5: 260℃; Zone 6: 265℃; and the die head temperature: 265℃.

[0059] Example 5

[0060] (1) Mix 520 parts of nylon 6-1, 45 parts of polyimide 2, 120 parts of intumescent flame retardant 1, 20 parts of hyperbranched polyamide 1, and 4 parts of antioxidant evenly.

[0061] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0062] The twin-screw extruder has the following temperature zones: Zone 1: 150℃; Zone 2: 240℃; Zone 3: 250℃; Zone 4: 255℃; Zone 5: 260℃; Zone 6: 265℃; and the die head temperature: 265℃.

[0063] Example 6

[0064] (1) Mix 520 parts of nylon 6-1, 45 parts of polyimide 2, 120 parts of intumescent flame retardant 1, 20 parts of hyperbranched polyamide 2, and 4 parts of antioxidant evenly.

[0065] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0066] The twin-screw extruder has the following temperature zones: Zone 1: 150℃; Zone 2: 240℃; Zone 3: 250℃; Zone 4: 255℃; Zone 5: 260℃; Zone 6: 265℃; and the die head temperature: 265℃.

[0067] Example 7

[0068] (1) Mix 520 parts of nylon 6-1, 45 parts of polyimide 2, 120 parts of intumescent flame retardant 1, 20 parts of hyperbranched polyamide 3, and 4 parts of antioxidant evenly.

[0069] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0070] The twin-screw extruder has the following temperature zones: Zone 1: 150℃; Zone 2: 240℃; Zone 3: 250℃; Zone 4: 255℃; Zone 5: 260℃; Zone 6: 265℃; and the die head temperature: 265℃.

[0071] Comparative Example 1

[0072] (1) Mix 520 parts of nylon 6-1, 45 parts of polyimide, 120 parts of intumescent flame retardant, 20 parts of hyperbranched polyamide, and 4 parts of antioxidant evenly.

[0073] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0074] The twin-screw extruder has the following temperature zones: Zone 1: 150℃; Zone 2: 240℃; Zone 3: 250℃; Zone 4: 255℃; Zone 5: 260℃; Zone 6: 265℃; and the die head temperature: 265℃.

[0075] In this comparative example, the polyimide was in the form of regular resin granules, not powder.

[0076] Comparative Example 2

[0077] (1) Mix 520 parts of nylon 6-1, 45 parts of polyimide 2, 120 parts of flame retardant melamine cyanurate (MCA), 20 parts of hyperbranched polyamide 1, and 4 parts of antioxidant evenly.

[0078] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0079] The twin-screw extruder has the following temperature zones: Zone 1: 150℃; Zone 2: 240℃; Zone 3: 250℃; Zone 4: 255℃; Zone 5: 260℃; Zone 6: 265℃; and the die head temperature: 265℃.

[0080] Comparative Example 3

[0081] (1) Mix 520 parts of nylon 6-1, 20 parts of polyimide 2, 120 parts of intumescent flame retardant 1, 20 parts of hyperbranched polyamide 1, and 4 parts of antioxidant evenly.

[0082] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0083] The twin-screw extruder has the following temperature zones: Zone 1: 150℃; Zone 2: 240℃; Zone 3: 250℃; Zone 4: 255℃; Zone 5: 260℃; Zone 6: 265℃; and the die head temperature: 265℃.

[0084] Comparative Example 4

[0085] (1) Mix 520 parts of nylon 6-1, 70 parts of polyimide 2, 120 parts of intumescent flame retardant 1, 20 parts of hyperbranched polyamide 1, and 4 parts of antioxidant evenly.

[0086] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0087] The twin-screw extruder has the following temperature zones: Zone 1: 150℃; Zone 2: 240℃; Zone 3: 250℃; Zone 4: 255℃; Zone 5: 260℃; Zone 6: 265℃; and the die head temperature: 265℃.

[0088] Comparative Example 5

[0089] (1) Mix 520 parts of nylon 6-1, 45 parts of polyimide 2, 120 parts of intumescent flame retardant 1, 50 parts of hyperbranched polyamide 1, and 4 parts of antioxidant evenly.

[0090] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0091] The twin-screw extruder has the following temperature zones: Zone 1: 150℃; Zone 2: 240℃; Zone 3: 250℃; Zone 4: 255℃; Zone 5: 260℃; Zone 6: 265℃; and the die head temperature: 265℃.

[0092] Comparative Example 6

[0093] (1) Mix 520 parts of nylon 6-1, 45 parts of polyimide 2, 120 parts of intumescent flame retardant 1, 20 parts of hyperbranched polyamide 1, and 4 parts of antioxidant evenly.

[0094] (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

[0095] The temperature of the twin-screw extruder is 120℃ in zone 1, 220℃ in zone 2, 230℃ in zone 3, 245℃ in zone 4, 240℃ in zone 5, 245℃ in zone 6, and 245℃ at the die head.

[0096] The processing temperature in this comparative example is the standard processing temperature for nylon 6.

[0097] Please see Table 1 for the data of each embodiment and comparative example.

[0098] The test methods and standards for each performance parameter in this invention are as follows:

[0099] Mechanical properties: Tensile strength is tested according to ISO 527-1 / -2, with a tensile speed of 5 mm / min.

[0100] ISO 179 / 1eA Test for Notched Impact Strength of Simply Supported Beams.

[0101] Flame retardant performance: According to UL94 standard, vertical burning of a 1.6mm thickness, with sample size of 125mm×13mm×5mm;

[0102] Limiting oxygen index: Tested according to GB2406-80 standard.

[0103] Table 1 Performance Data

[0104]

[0105] As can be inferred from the table above, in this invention, the intumescent flame retardant can assist polyimide and nylon 6 to quickly form char on their surfaces, generating a char-like foam layer, and thus exhibits the best flame retardant performance.

[0106] The core of the polyimide chemical structure—the imide bond—endows polyimides with extremely high thermal and chemical stability, enabling them to maintain excellent performance in extreme environments. Polyimides with ultrafine particle sizes can be more uniformly dispersed in polyamides, resulting in optimal flame retardant performance. At higher melting temperatures, nylon 6 with a lower melt index can better plasticize with polyimides and intumescent flame retardants, further enhancing mechanical and flame retardant properties. Appropriate amounts of terminally amino hyperbranched polyamide can enhance the mechanical and flame retardant properties of nylon 6 compositions; however, excessive amounts can lead to a significant decrease in the composition's toughness.

[0107] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A flame retardant nylon 6 composition characterized in that, It is prepared from the following components in parts by weight: 600-500 parts of nylon 6500, 30-50 parts of polyimide, 30-150 parts of intumescent flame retardant, 0-30 parts of hyperbranched polyamide, and 1-10 parts of antioxidant.

2. The flame retardant nylon 6 composition of claim 1, wherein, The nylon 6 described herein has a melt flow index of 1-10 g / 10 min under test conditions of 235°C and 2.16 kg load, according to ASTM D1238-2010 standard.

3. The flame retardant nylon 6 composition of claim 1, wherein, The polyimide is an ultrafine powder with a mesh size of not less than 400 mesh; the hyperbranched polyamide has a molecular weight of 500-3000.

4. The flame retardant nylon 6 composition of claim 1, wherein, The intumescent flame retardant contains an acid source, a carbon source, and a gas source.

5. The flame retardant nylon 6 composition of claim 4, wherein, The acid source is at least one of phosphoric acid, boric acid, sulfuric acid, and phosphate ester; the carbon source is at least one of starch, sucrose, dextrin, pentaerythritol, ethylene glycol, and phenolic resin; and the gas source is at least one of urea and melamine.

6. The flame retardant nylon 6 composition of claim 4, wherein, The acid source is at least one of triphenyl phosphate and ammonium polyphosphate.

7. The flame retardant nylon 6 composition of claim 1, wherein, The antioxidant is at least one of hindered amines, hindered phenols, thiolated antioxidants, and phosphite antioxidants.

8. The flame-retardant nylon 6 composition as claimed in claim 1, characterized in that, The antioxidant is at least one of antioxidant 1010, antioxidant 1098, antioxidant 1076, antioxidant 300, and antioxidant 168.

9. A method for preparing a flame-retardant nylon 6 composition, comprising the following steps: (1) Mix 500-600 parts of nylon 6, 30-50 parts of polyimide, 30-150 parts of intumescent flame retardant, 0-30 parts of hyperbranched polyamide, and 1-10 parts of antioxidant evenly. (2) The above mixture is placed in a twin-screw extruder, melt-extruded and then granulated to obtain the flame-retardant nylon 6 composition.

10. The method for preparing the flame-retardant nylon 6 composition according to claim 9, characterized in that, The twin-screw extruder has the following temperature zones: Zone 1: 130-180℃; Zone 2: 220-240℃; Zone 3: 230-250℃; Zone 4: 235-255℃; Zone 5: 240-260℃; Zone 6: 250-265℃; and the die head temperature: 250-265℃.

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