Electricity, like water and air, has become an indispensable source of energy for human life, and people can hardly live without electricity at all times, whether at home or at work As one of the toughest engineering thermoplastics, PBT (Polybutylene Terephthalate) is widely used in the fields of electronic appliances, home appliances, automobiles and the like due to its excellent flame retardancy and high temperature resistance. Is a veritable electricity security 'guards'.
PBT main application areas
PBT is one of the engineering plastics whose growth rate surpasses the average growth rate of the market. About one-third of them are mainly used in automobile manufacturing, electrical engineering and electronics (such as housings, sockets, etc.) and general applications. Compared to engineering thermoplastics, PBT's annual growth rate is above average, at around 7%, making it an economically attractive class of material, prompting modified plastics producers to technically study the material One of the reasons for the cost-benefit of customers.
1. PBT structure and performance
The molecular structure of PBT
The molecular structure of PBT is shown in the figure. It can be seen from the molecular structure that the PBT macromolecule has a linear structure and a regular structure. There are active benzene rings and polar ester groups in the repeating structural units. Since the benzene ring and the ester group Between the formation of a conjugate system, the molecular rigidity larger, reducing the flexibility of the molecular chain, solubility and water absorption. Polar ester group, the presence of carbonyl, increased intermolecular force, the intermolecular Closely linked, rigid chain strengthened.High temperature, the ester group makes it easy to hydrolysis and fracture, thus affecting the performance of the polymer. Structural unit also has four non-polar methylene - (CH2) -, compared with PET More than 2, the flexibility of the molecular chain increases, arranged more regular, so the crystallization of materials higher than PET, crystallization speed at low temperatures, easy molding.
The solubility parameter of PBT is 10.8 (J / cm3) 1/2, which is similar to many plastics, so its blending range is relatively wide.Otherwise, PBT contains hydroxyl or carboxyl at the molecular chain end, which is easy to react with epoxy, anhydride, Carboxyl or hydroxyl and other chemical reactions, when blended with these functional groups can be better mixed with the toughening agent, toughening agent and the interface with increased adhesion, so as to achieve better toughening effect.
PBT resin has excellent mechanical properties, good weatherability, low moisture absorption, good electrical insulation, amorphous polyester has good optical transparency, but there are still some shortcomings PBT, its notched impact strength is low, The flame retardancy is not high, the heat distortion temperature is low, the dimensional stability is poor at high temperature, anisotropy.Combined with the excellent performance of PBT, aiming at its deficiency, the modification of PBT becomes an important means to expand the use of PBT.
2. PBT modification and product applications
There are a great variety of PBTs, and most of the PBTs need to be modified in order to meet the corresponding requirements in practical applications. PBT modification is mainly divided into: flame retardant PBT, glass fiber reinforced flame retardant PBT, glass fiber reinforced PBT, PBT Modified PBT material is mainly used in the field of electronic appliances such as relay housings and bobbins, lamp housings, sockets, optical fiber connectors, etc. In the field of automobile manufacturing, such as junction boxes, ignition system components, exterior door handles and the like.
The following describes several PBT main products and requirements:
(1) LED lamp or energy-saving lamp housing
In the lighting industry, most of the lamp shell is made of flame-retardant PBT material, the appearance of which requires transparent or opaque color, smooth surface, no floating fiber, the performance requirements of flame retardant 3.2mm or 1.6mm flame retardant V0, high temperature, Anti-yellowing effect, good mechanical properties, easy to process.
According to the needs of customers, the product research and development of the lamp shell is divided into the transparent flame retardant PBT products (TG15EX, TG25EX, TG30EX, etc.) and the light shielding PBT products (TGM20EX). The light shielding PBT (TGM20EX) The degree of shading 0.8mm product thickness opaque. The above two types of products are used for plastic lighting shell and plastic lighting shell, the product shown in Figure 2. One for the plastic lighting aluminum products, materials, To meet the customer terminal products in -30 ℃ ~ 120 ℃ high and low temperature cycle test 200 times to 500 times.
LED lamp housing
(2) connector
Electronic connector products are mainly 30% glass fiber reinforced flame retardant materials, there are 15% glass fiber reinforced or non-reinforced flame retardant materials.Jinla on the electronic connector products launched TG30EX and TG15EX two materials, its performance to meet Flame retardant grade 3.2mm or 1.6mmV0, high strength and toughness, can withstand multiple insert and pull out. Appearance requirements good gloss, no obvious floating fiber, the product shown in Figure 3.
Connector
(3) National Grid terminal
National grid dedicated terminal mainly 30% glass fiber reinforced flame retardant materials, Jinli has developed two corresponding products, namely TG30EX-4U and TG30EX-6U, its performance in line with the National Grid on the terminal material requirements of the product, that is, hot Wire Flammability Index GWFI 960 ℃, high strength and toughness, the appearance of PANTONE 4U and 6U color-based.
National Grid dedicated terminal
(4) computer cooling fan
Computer cooling fan due to the CPU surface temperature up to 130 ~ 140 ℃, so the material can withstand long-term high temperature conditions, at the same time due to direct contact with the metal coil, the material also need to have a higher flame retardant. In addition, the cooling fan needs to pass Strict dynamic balance test, so the material needs good fluidity, dimensional stability.Jinlai introduced for the cooling fan 30% glass fiber reinforced flame retardant PBT material TG30EX, the flame retardant grade of 1.6mmV0, with excellent flow Sexual and dimensional stability, to meet the requirements of materials, high temperature conditions.
Cooling fan
(5) relay
The coil axis within the relay generally requires the material has good insulation, high heat resistance, high flame resistance, high flow, high stiffness. Applicable materials are phenolic resin, PBT, PA6, PET. PBT material flow is good, Crystallization speed, high heat resistance, so for the small size, complex shape products have greater advantages.Jinjian for the relay coil axis products launched 30% glass fiber reinforced flame retardant PBT material, grade TG30WX, Flame retardant up to 0.35mmV0, UL cards have been.
Relay
(6) optical fiber connector
Optical fiber connector type, the connector material is mainly plastic, is conducive to plug the convenience, high density, but its small size, thin parts, long-term and electrical contact, so the product of the material flow, toughness, flame retardancy and Dimensional stability of the higher requirements. Jin 旸 developed on this flame retardant 1.6mmV0, high toughness, good fluidity TG15EX products, the resulting product size and stability, can withstand multiple plug.
Optical connector
(7) automotive materials
In the field of automobile manufacturing, the modified PBT is mainly used in automobile bumpers, automobile headlamp lighting rings, automobile transmission gear boxes, motor housings, etc. PBT materials used for automobile headlamp lighting rings require high temperature resistance and fluidity Good and easy to shape.Jinlai introduced two suitable for automotive headlamp lighting ring products TM20E and TM00E. TM20E is mineral filled PBT / PET, the product is suitable for primed automotive headlamp lighting and mirrors, with high resistance Heat, excellent mechanical properties and visual effects. TM00E to be primed PBT, with good processing properties, high gloss, low precipitation apparent effect, the injection of the product to achieve a high glossy surface effect, without spray primer Vacuum aluminum.
Car headlights