Views: 12 Author: Site Editor Publish Time: 2023-11-16 Origin: Site
Transparent nylon is a polymer material with excellent comprehensive properties. It not only has advantages such as high mechanical strength, good thermal stability, and excellent corrosion resistance, but also has advantages such as easy forming and processing, good dimensional stability, low linear expansion coefficient, high cost-effectiveness, excellent electrical insulation and aging resistance, non-toxic, odorless, and easy to form alloys with other amorphous or semi crystalline polyimide.
On the one hand, it has excellent transparency (even surpassing PC and approaching PMMA), and on the other hand, it is superior to general transparent polymer materials (such as PS, PC, PMMA, etc.) in terms of resistance to environmental stress cracking, oil resistant solvents, scratch resistance, and wear resistance.
1.Modified preparation
Due to the fact that nylon is a semi crystalline polymer and usually presents a white semi transparent shape, in order to produce nylon with high light transmittance, three aspects can be considered:
(1) Reduce the crystallization ability of polyaniline to obtain amorphous products;
(2) Reducing the size of the crystal in the crystal region to make the diameter of the crystal smaller than the wavelength of visible light, and the seeding method is also known as microcrystallization;
(3) By blending, copolymerization, and other methods to modify the refractive indices of the amorphous and crystalline regions, the polycoaniline can be adjusted to have the same refractive index.
The main method of transparent nylon suppliers is to introduce monomers with side groups or ring structures to disrupt molecular chain regularity and obtain amorphous or microcrystalline transparent nylon. Common types of transparent nylon include PA MACM12, PA 12/MACMI, PA 6I/X, and so on.
Due to the wide selection of monomers for circular or side chain structures, the composition of transparent nylon varies for almost every brand. Here are two varieties to illustrate.
One is PA TMDT (TMD is a mixture of 2,2,4 and 2,4,4-trimethylhexanediamine, T is terephthalic acid), such as Evonik's Trogamid T series, whose aromatic cyclic structure further prevents molecular bonding between polymer chains, forming amorphous polymers with high transparency.
There is also PACM12, which further replaces aromatic ring monomers with aliphatic ring monomers, achieving the semi crystalline state of the polymer. However, because its crystal size can only reach the nanoscale and does not affect visible light propagation, it maintains the high transparency of the material.
2. Processing injection molding and precautions
The injection molding temperature of transparent nylon is 300-315 ℃. During molding, it is necessary to strictly control the barrel temperature. If the melt temperature is too high, it will cause discoloration of the product due to degradation, while if the temperature is too low, it will affect the transparency of the product due to poor plasticization. Try to keep the mold temperature as low as possible, as high mold temperatures can reduce the transparency of the product due to crystallization.
Some transparent nylon parts can sometimes see some sparkling fine silver lines through light, which are also known as speckles or cracks. The following solutions can be used:
(1) Eliminate the interference of gases and other impurities, and fully dry the plastic.
(2) Reduce the material temperature, adjust the temperature of the material barrel in stages, and appropriately increase the mold temperature.
(3) Increase injection pressure and reduce injection speed.
(4) Increase or decrease the back pressure of pre molding and reduce the screw speed.
(5) Improve the exhaust conditions of the flow channel and cavity.
(6) Clean any possible blockages in the nozzle, runner, and gate.
(7) Shorten the forming cycle and use annealing method to eliminate silver lines after demolding.
3.Application
Transparent nylon is now widely used in mechanical and electrical components related to fuel and oil, such as lighter oil tanks, flow meter sleeves, filter covers, filter cups, circuit breakers, and high-voltage switch housings. Especially in the fields of precision optical instruments, pressure resistant windows, observation glasses, special lamp covers, food packaging films, high-end sports equipment, etc., other materials cannot replace it. In addition, transparent nylon is also widely used in household appliances, such as in kitchen appliances such as hot water kettles, baby food dispensers, baby spoons, coffee beans, milk containers, and multifunctional cooking machines.
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