A halogen-free flame-retardant long carbon chain polyamide composition which can be porcelainized and a method for preparing the same

Abstract

The application discloses a porcelainable halogen-free flame-retardant long carbon chain polyamide composition and a preparation method thereof. The composition is prepared from the following components according to weight parts: long carbon chain polyamide 25-35 parts, polyethylene 5-25 parts, compatibilizer 3-10 parts, porcelain-forming filler 15-25 parts, porcelain-forming auxiliary 5-15 parts, halogen-free flame retardant 15-20 parts, carbon-forming agent 1-5 parts, foaming agent 0.2-3 parts, antioxidant 0.2-3 parts, and other auxiliary 0.2-3 parts. The melt index of the long carbon chain polyamide under the condition of 235 DEG C / 2.16 kg is 10-30 g / 10 min, and the melt index of the polyethylene under the condition of 235 DEG C / 2.16 kg is 15-35 g / 10 min. By adjusting the melt indexes of the polyethylene and the long carbon chain polyamide, the phase states of the two in the composition can be regulated to a certain extent, the polyethylene in the composition is more enriched on the surface layer, and the filler is selectively distributed in the polyethylene phase with lower viscosity, so that the content of the porcelain-forming filler on the surface layer of the composition is increased, and the use amount of the filler for forming the complete ceramic self-supporting body of the composition is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer material modification, and particularly relates to a porcelainizable halogen-free flame-retardant long carbon chain polyamide composition and a preparation method thereof. BACKGROUND

[0002] The long carbon chain polyamide refers to a polyamide variety in which the number of methylene groups between adjacent amide bonds in a molecular main chain is not less than 10. Due to the long methylene chain segment between adjacent amide groups, the long carbon chain polyamide has the characteristics of relatively small density, low water absorption, good dimensional stability, excellent solvent resistance, good electrical properties, corrosion resistance, wear resistance, tough texture, fatigue resistance and outstanding low-temperature resistance, and is widely used in the fields of special pipelines such as automobile brake pipes, oil pipes, clutch hoses, cooling pipes, busbars and submarine cables and special cables.

[0003] Compared with other polyamide family members, the long carbon chain polyamide has longer methylene units, so that its flame retardancy is insufficient. The flame retardant long carbon chain polyamide material is usually realized by copolymerization and / or blending. However, due to the low amide bond density and poor char forming property, the long carbon chain polyamide is difficult to form a complete barrier layer with sufficient structural strength during the combustion process, and cannot well prevent the spread of high temperature and flame. In particular, as a cable coating material, it is required to ensure that the electrical circuit does not short circuit in a short time, so that high performance of the coating material is required.

[0004] At present, the long carbon chain polyamide fire-resistant material is processed by taking a long carbon chain polyamide composition as an insulating outer layer and taking mica tape as a fireproof inner layer. The biggest advantage of the long carbon chain polyamide fire-resistant material is soft texture, which is suitable for mobile occasions. However, the cable manufacturing process is complicated, and the mechanical strength of the coating layer is greatly reduced after long-time high-temperature ablation. The coating layer is easy to powder and fall off after being shaken, and it is difficult to provide long-time reliability guarantee for the circuit system in a thermal runaway state. SUMMARY

[0005] Therefore, the present application provides a porcelainizable halogen-free flame-retardant long carbon chain polyamide composition and a preparation method thereof. The composition achieves the effect of extinguishing open flame below 900 DEG C, and forms a complete foam ceramic layer above 900 DEG C, so as to realize the fire resistance function.

[0006] To achieve the above object, the present application provides the following technical scheme.

[0007] In one aspect, the present application discloses a porcelainizable halogen-free flame-retardant long carbon chain polyamide composition, which is prepared from the following components in parts by weight:

[0008]

[0009] The long carbon chain polyamide has a melt index of 10-30 g / 10 min under the condition of 235℃ / 2.16 kg, and the polyethylene has a melt index of 15-35 g / 10 min under the condition of 235℃ / 2.16 kg.

[0010] As a further aspect of the present application, the long carbon chain polyamide is at least one of PA510, PA512, PA513, PA514, PA515, PA610, PA612, PA613, PA614, PA615, PA1010, PA1012, PA1013, PA1014, PA1015, PA11, PA12, PA1212, PA1213, PA1214, and PA1215.

[0011] As a further aspect of the present application, the polyethylene is at least one of HDPE, LDPE, and LLDPE.

[0012] As a further aspect of the present application, the compatibilizer is at least one of maleic anhydride grafted LLDPE, maleic anhydride grafted LDPE, and maleic anhydride grafted POE.

[0013] As a further aspect of the present application, the ceramic-forming filler is at least one of wollastonite, talcum powder, mica, diatomite, kaolin, and glass fiber; and the ceramic-forming auxiliary agent is glass powder and / or zinc borate, wherein the glass powder is at least one of low-temperature glass powder, medium-temperature glass powder, and high-temperature glass powder.

[0014] As a further aspect of the present application, the halogen-free flame retardant is at least one of nitrogen-based flame retardant, phosphorus-based flame retardant, nitrogen-phosphorus composite flame retardant, and inorganic flame retardant; the charring agent is at least one of triazine charring agent and resin charring agent; and the foaming agent is at least one of potassium carbonate and sodium carbonate.

[0015] As a further aspect of the present application, the antioxidant is at least one of hindered phenol antioxidant, amine antioxidant, phosphite antioxidant, and thioester antioxidant.

[0016] As a further aspect of the present application, the other auxiliary agent is at least one of amide compound, stearate compound, metal soap compound, and color masterbatch.

[0017] Another aspect of the present application discloses a preparation method of the above-mentioned ceramic-formable halogen-free flame-retardant long carbon chain polyamide composition, comprising the following steps:

[0018] S1: long carbon chain polyamide, polyethylene, compatibilizer, and antioxidant are weighed by weight parts, and are placed in a high-speed mixer for stirring for 5-10 min to obtain a mixture A;

[0019] S2: the porcelain-forming filler, porcelain-forming auxiliary agent, halogen-free flame retardant, carbon-forming agent, foaming agent, and other auxiliary agent are weighed by weight parts, placed in a high-speed mixer, and stirred for 10-15 min to obtain a mixture B;

[0020] S3: the material A is added to the main feeding port of the twin-screw extruder, and the material B is added to the side feeding port, and after melting, extrusion, granulation, and drying, the product is obtained.

[0021] As a further aspect of the present application: the temperature of one zone of the twin-screw extruder is 150-190℃, and the temperature of other zones and the head is 180-250℃; the screw rotation speed is 200-600r / min.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] By adjusting the melt index of polyethylene and long-chain polyamide, the phase state of the two in the composition can be regulated to a certain extent. Under the condition of 235℃ / 2.16kg, the melt index of polyethylene is 15-35g / 10min, and the melt index of long-chain polyamide is 10-30g / 10min. The polyethylene in the composition will be more enriched in the surface layer, and the filler will be selectively distributed in the polyethylene phase with lower viscosity, thereby increasing the content of the porcelain-forming filler in the surface layer of the composition, and effectively reducing the amount of filler used to form a complete ceramic self-supporting body.

[0024] The composition is basically the same as the conventional flame-retardant long-chain polyamide in the processes of blending extrusion, part injection molding, etc. During the process of the composition being exposed to high temperature and open flame, the flame retardant decomposes and releases a large amount of non-toxic gas that can inhibit the spread of flame, and at the same time, expands to form a sponge-like foam structure, and forms a porous expanded carbon layer under the action of the carbon-forming agent. The porous carbon layer structure is fixed in the ceramic layer formed by the porcelain-forming filler, forming a porous ceramic layer, which can isolate the spread of flame and has good heat insulation property. The added glass powder and / or zinc borate can play a bridging role in the porcelain-forming process, forming a "eutectic mixture" at the edge of the porcelain-forming filler, and forming a condensed ceramic product during cooling. This ceramic body has self-supporting property and can withstand certain mechanical impact and vibration, realizing the fire resistance function. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to specific embodiments. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0027] The specific information of raw materials used in the following examples and comparative examples is shown in Table 1:

[0028] Table 1

[0029]

[0030]

[0031] All materials are commercially available conventional products.

[0032] It can be understood that the above raw material reagents are only examples of some specific embodiments of the present application, so that the technical solutions of the present application are more clear, and do not represent that the present application can only use the above reagents, and the specific scope is subject to the scope of claims. In addition, the "parts" described in the examples and comparative examples refer to weight parts unless otherwise specified.

[0033] Any range recited herein includes the end values and any number or value between the end values, as well as any range formed by the end values or any number or value between the end values.

[0034] The examples and comparative examples are prepared by the following method:

[0035] S1: The components were weighed according to the proportions in Table 1, and the long carbon chain polyamide, polyethylene, compatibilizer and antioxidant were placed in a high-speed mixer and stirred for 5-10 min to obtain a mixture A;

[0036] S2: The ceramic filler, ceramic auxiliary agent, halogen-free flame retardant, carbon agent, foaming agent and other auxiliary agents were placed in a high-speed mixer and stirred for 10-15 min to obtain a mixture B;

[0037] S3: The material A was added to the main feeding port of the twin-screw extruder, and the material B was added to the side feeding port. After melting, extrusion, granulation and drying, it was obtained.

[0038] In examples 1-3 and comparative examples 1-7, the temperature of the first zone of the twin-screw extruder was set to 180℃, and the temperature of the other zones and the die head was set to 230℃, and the screw speed was 300r / min. In examples 4 and 5, the temperature of the first zone of the twin-screw extruder was set to 180℃, and the temperature of the other zones and the die head was set to 235℃, and the screw speed was set to 300r / min.

[0039] Table 2

[0040]

[0041]

[0042] The halogen-free flame-retardant long carbon chain polyamide composition particles prepared in the above examples were homogenized, injection molded into a sample strip, and subjected to performance testing. The test items and results are shown in Table 3:

[0043] Table 3

[0044]

[0045] The test standards for the test items in Table 3 are as follows:

[0046] The tensile strength and elongation at break before ablation were tested in accordance with the GB / T 1040.1-2018 standard, the flame retardation was tested in accordance with the UL94 standard (thickness 1.6 mm), and the bending strength of the sample after ablation was tested in accordance with the GB / T 6569-2006 “Fine Ceramic Bending Strength Test” standard. The porcelain effect was visually observed and rated from 0 to 10, with the porcelain integrity of Example 1 being the best at 10 and the porcelain integrity of Comparative Example 3 being the worst at 0.

[0047] According to the test results in Table 3, the porcelainizable halogen-free flame-retardant long carbon chain polyamide composition of Examples 1-5 all achieved V0 flame retardation (thickness 1.6 mm), and formed a complete ceramic layer with high bending strength after sintering.

[0048] A comprehensive comparison of Examples 1-5 and Comparative Examples 1-2 shows that by using a polyethylene resin with a suitable melt index and a compatibilizer, a composition with a surface rich in polyethylene is prepared, so that more fillers in the system are distributed on the surface of the composition, which can effectively reduce the amount of fillers used to form a complete ceramic self-supporting body.

[0049] A comprehensive comparison of Example 1 and Comparative Examples 3-4 shows the synergistic effect of the porcelainizing filler and the porcelainizing aid in the porcelainizing process of the composition. The low-melting-point glass powder of the porcelainizing aid rapidly changes to a liquid state after reaching the initial melting temperature (330°C), and during the sintering process, the porcelainizing aid is fully enriched around the structure of the porcelainizing filler, acting as a bridge, so that the edges of the porcelainizing filler rapidly melt and adhere to each other to form a self-supporting structure.

[0050] A comprehensive comparison of Example 1 and Comparative Examples 5-7 shows the flame-retardant synergistic effect of the flame retardant, the char-forming agent, and the foaming agent. During the heating or burning process of the composition, a phosphorus-carbon foam layer is formed, which has good flame-retardant effect due to its heat insulation, oxygen insulation, and oxygen suppression. At the same time, the decomposition of the foaming agent produces metal oxides, which can act as a solubilizing agent to further improve the porcelainizing effect of the composition, and the carbon dioxide gas can bring more microporous structure to the ceramic layer to achieve better flame-retardant and heat-insulating effect.

[0051] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0052] Therefore, the above description is only a preferred embodiment of this application and is not intended to limit the scope of this application; that is, all equivalent modifications made in accordance with the scope of the claims of this application shall be within the protection scope of the claims of this application.

Claims

1. A ceramic-compatible halogen-free flame-retardant long-chain polyamide composition, characterized in that, It is prepared from the following components in parts by weight: 25-35 parts of long-chain polyamide, 5-25 parts of polyethylene Compatibilizer 3-10 parts, 15-25 parts of ceramic filler 5-15 parts of porcelain-forming additives 15-20 parts of halogen-free flame retardant 1-5 parts of charring agent Foaming agent 0.2-3 parts, Antioxidant 0.2-3 parts, Other additives: 0.2-3 parts; The melt index of the long-chain polyamide at 235℃ / 2.16kg is 10~19g / 10min, and the melt index of the polyethylene at 235℃ / 2.16kg is 30~35g / 10min. The halogen-free flame retardant is a compound of OP1230 flame retardant and MCA flame retardant; The char-forming agent is a triazine-based char-forming agent; The ceramic filler is at least one of wollastonite and mica powder; The ceramic-forming aid is at least one of glass powder and zinc borate; The foaming agent is at least one of potassium carbonate and sodium carbonate.

2. The ceramicizable halogen-free flame-retardant long-chain polyamide composition according to claim 1, characterized in that, The long-chain polyamide is at least one of PA510, PA512, PA513, PA514, PA515, PA610, PA612, PA613, PA614, PA615, PA1010, PA1012, PA1013, PA1014, PA1015, PA11, PA12, PA1212, PA1213, PA1214, and PA1215.

3. The ceramicizable halogen-free flame-retardant long-chain polyamide composition according to claim 1, characterized in that, The polyethylene is at least one of HDPE, LDPE, and LLDPE.

4. The ceramic-compatible halogen-free flame-retardant long-chain polyamide composition according to claim 1, characterized in that, The compatibilizer is at least one of maleic anhydride-grafted LLDPE, maleic anhydride-grafted LDPE, and maleic anhydride-grafted POE.

5. The ceramicizable halogen-free flame-retardant long-chain polyamide composition according to claim 1, characterized in that, The glass powder is at least one of low-temperature glass powder, medium-temperature glass powder, and high-temperature glass powder.

6. The ceramicizable halogen-free flame-retardant long-chain polyamide composition according to claim 1, characterized in that, The antioxidant is at least one of hindered phenolic antioxidants, amine antioxidants, phosphite antioxidants, and thioester antioxidants.

7. The ceramicizable halogen-free flame-retardant long-chain polyamide composition according to claim 1, characterized in that, The other additives are at least one of amide compounds, stearate compounds, metal soap compounds, and color masterbatches.

8. The method for preparing the ceramic-compatible halogen-free flame-retardant long-chain polyamide composition according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Weigh the long-chain polyamide, polyethylene, compatibilizer and antioxidant according to the weight parts, put them in a high-speed mixer and stir for 5-10 minutes to obtain mixture A; S2: Weigh out the ceramic filler, ceramic additive, halogen-free flame retardant, charring agent, foaming agent and other additives according to the weight parts, put them in a high-speed mixer and stir for 10~15 minutes to obtain mixture B; S3: Add material A to the main feed port of the twin-screw extruder and material B to the side feed port. After melting, extrusion, pelletizing and drying, the product is obtained.

9. The preparation method according to claim 8, characterized in that, The temperature of the first zone of the twin-screw extruder is 150~190℃, and the temperature of the other zones and the die head is 180~250℃; the screw speed is 200~600r / min.

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