Main factors affecting the effect of flame retardant nylon
2023-10-11 02:08:08
Main factors affecting the effect of flame retardant nylon
First, the selection of flame retardants, select appropriate flame retardants for different occasions and requirements;
Secondly, if the flame retardant dosage and synergistic combination are single flame retardant, the red phosphorus and bromine flame retardant have better flame retardant effect. When the red phosphorus dosage is 5% to 7%, the amount of bromine flame retardant is When 15% to 17%, the vertical burning of nylon can reach V-0; the nitrogen-based flame retardant can only make the vertical burning grade of nylon reach V-2 when the dosage is large. If the three flame retardants are used in combination with each other, the amount of the flame retardant is reduced, and the effect is more remarkable. See the following table: Flame retardant effect of the composite flame retardant system Flame retardant system Oxygen index Flame retardant grade 15% N + 5% phosphorus 27.9 V-0 12 % bromine + 3% phosphorus 29.0 V-010% N + 8% bromine 29.5 V-0 It can be seen that the synergistic effect of the flame retardant can not only improve the flame retardant effect of the nylon product, but also reduce the amount of the flame retardant, thereby cut costs. However, the ratio between the flame retardants and the dispersion of the flame retardant in the nylon matrix are the direct cause of the flame retardant effect. The surface treatment of the flame retardant and the nylon can be improved to improve the compatibility between the flame retardant and the resin. Sexuality to optimize the synergistic effect of the flame retardant.
Third, the influence of moisture in the raw material contains a strong polar amide (-CONH-) group in the molecular structure of the nylon, which is exposed in the air and easily combines with water molecules in the air to form a hydrogen bond, which has a large water absorption. This makes the nylon easily hydrolyzed in a high-temperature molten state, lowers its molecular weight, and further reduces its mechanical properties. Therefore, the nylon raw material must be sufficiently dried before processing.
Drying conditions are: blast drying temperature 100 ° C ~ 110 ° C time is 6 ~ 8h vacuum drying temperature 85 ± 5 ° C time is 6 ~ 8h
Fourth, the influence of processing temperature The processing temperature in the extrusion molding process should follow the following principle: the temperature of the feed section is slightly lower than the melting point of the raw material, so that the nylon is in a semi-molten state; this is to ensure that the material can stably enter the screw and can The screw is conveyed in the axial direction; the temperature of the compression section is higher than the melting point, generally about 10~15 °C, so that it is completely melted; in this section, the nylon melt is subjected to screw shear mixing, which will cause large shear and friction. Heat; the temperature of the metering section is close to or slightly lower than the compression section. In this zone, the nylon melt is evenly heated and easy to achieve stable flow; the head temperature is slightly lower than the metering section, which is close to the melting point temperature to avoid the melt. The thickness of the product is uneven due to cracking; the temperature of the cooling medium and the cooling rate should also be appropriately adjusted.
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Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
First, the selection of flame retardants, select appropriate flame retardants for different occasions and requirements;
Secondly, if the flame retardant dosage and synergistic combination are single flame retardant, the red phosphorus and bromine flame retardant have better flame retardant effect. When the red phosphorus dosage is 5% to 7%, the amount of bromine flame retardant is When 15% to 17%, the vertical burning of nylon can reach V-0; the nitrogen-based flame retardant can only make the vertical burning grade of nylon reach V-2 when the dosage is large. If the three flame retardants are used in combination with each other, the amount of the flame retardant is reduced, and the effect is more remarkable. See the following table: Flame retardant effect of the composite flame retardant system Flame retardant system Oxygen index Flame retardant grade 15% N + 5% phosphorus 27.9 V-0 12 % bromine + 3% phosphorus 29.0 V-010% N + 8% bromine 29.5 V-0 It can be seen that the synergistic effect of the flame retardant can not only improve the flame retardant effect of the nylon product, but also reduce the amount of the flame retardant, thereby cut costs. However, the ratio between the flame retardants and the dispersion of the flame retardant in the nylon matrix are the direct cause of the flame retardant effect. The surface treatment of the flame retardant and the nylon can be improved to improve the compatibility between the flame retardant and the resin. Sexuality to optimize the synergistic effect of the flame retardant.
Third, the influence of moisture in the raw material contains a strong polar amide (-CONH-) group in the molecular structure of the nylon, which is exposed in the air and easily combines with water molecules in the air to form a hydrogen bond, which has a large water absorption. This makes the nylon easily hydrolyzed in a high-temperature molten state, lowers its molecular weight, and further reduces its mechanical properties. Therefore, the nylon raw material must be sufficiently dried before processing.
Drying conditions are: blast drying temperature 100 ° C ~ 110 ° C time is 6 ~ 8h vacuum drying temperature 85 ± 5 ° C time is 6 ~ 8h
Fourth, the influence of processing temperature The processing temperature in the extrusion molding process should follow the following principle: the temperature of the feed section is slightly lower than the melting point of the raw material, so that the nylon is in a semi-molten state; this is to ensure that the material can stably enter the screw and can The screw is conveyed in the axial direction; the temperature of the compression section is higher than the melting point, generally about 10~15 °C, so that it is completely melted; in this section, the nylon melt is subjected to screw shear mixing, which will cause large shear and friction. Heat; the temperature of the metering section is close to or slightly lower than the compression section. In this zone, the nylon melt is evenly heated and easy to achieve stable flow; the head temperature is slightly lower than the metering section, which is close to the melting point temperature to avoid the melt. The thickness of the product is uneven due to cracking; the temperature of the cooling medium and the cooling rate should also be appropriately adjusted.
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Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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