In recent years, the amount of indoor hot water pipes has soared, especially the gradual popularization of low-temperature hot water radiant heating. Various pipes have applications, such as PPR (random copolymer polypropylene) pipe, PEXa (peroxide cross Co-high density polyethylene) pipe, PEXb (silane grafted hydrolyzed cross-linked high density polyethylene) pipe, PB (polybutylene) pipe, PE-aL-PEXb (aluminum-plastic composite) pipe, CPVC (chlorinated polyvinyl chloride) Tube, PERT (temperature resistant medium density polyethylene) tube, etc. Among them, some materials are not very familiar with the pipeline, such as PB (polybutylene) tube. The main features of polybutene and its pipelines are described below:
Polybutene (PB) resins are poly(1-butene) based semi-crystalline polyolefin thermoplastics including homopolymers and a range of poly(1-butene/ethylene) copolymers. The main applications are pipe, pipe fittings, packaging, hollow blow molding containers, hot melt adhesives and sealants, and polymer modification.
PB is a 1-butene monomer produced by isotactic Ziegler-Natta polymerization. Commercial products are polymers based on isotactic (98% to 99.5%) and high molecular weight (average molecular weight of 230,000 to 750,000). There are five kinds of crystal deformations known as poly 1-butene: type I; type II; type III; type I'; type II'. The glass transition temperature ranges from about -20 ° C for the homopolymer to -34 ° C for the high ethylene content copolymer. The crystallization reaction of the melt first produces a tetragonal crystalline metastable state II; at ambient temperature and pressure, the homopolymer undergoes irreversible transformation from the type II to the steady state I of the twin hexagonal form over 5 days to 7 days. This process takes from 1 day to 3 days for the copolymer.
For various homopolymers, the melting point of Form I is from 107 ° C to 130 ° C, from 114 ° C to 118 ° C for copolymers with low ethylene content and 90 ° C for copolymers with high ethylene content. 95 ° C. After conversion to Form I, the homopolymer has a crystallinity of 48% to 55% by weight, and the copolymer has an ethylene content of 35% to 45%.
PB resins are generally resistant to acids, bases, solvents, paraffinic oils and naphthenic oils, detergents and various chemicals, but are less tolerant at elevated temperatures. The resin also has good moisture barrier properties and electrical insulation properties. The material exhibited a wide range of flexural properties, with a tensile modulus of 286 MPa for the homopolymer and 52 MPa for the high ethylene content copolymer. PB is particularly resistant to creep, environmental stress, chemical and abrasion. All grades are supplied in pellets. A PB resin having a melt index (MI) of 0.4 g/10 min (aSTMD-1238, condition E) can be used to process hot and cold water pipes. A PB resin having a MI of 1 g/10 min is mainly used for processing a packaging film. A general-purpose homopolymerized PB resin having an MI of 0.4 to 200 can be blended with other polyolefins to enhance impact strength. High ethylene content copolymerized PB resins with a MI of 0.25 to 750 can improve processability and other properties when blended with other polyolefins.
Here, we mainly discuss the PB pipe resin with MI=0.4. Through the ordinary single-screw extruder pipe production line, various specifications of hot and cold water pipes can be produced, and the pipe fittings can be produced by ordinary injection molding machines.
The polybutene (PB) tube has excellent heat-resistant creep properties and excellent performance at high temperatures, and can reach 82.2 ° C, which means that it can be used for a long time at this temperature, and the short-time use temperature can be as high as 95 ° C. PB pipe is light, flexible and impact resistant. It can be used in hot and cold water systems instead of copper pipes and aluminum-plastic pipes. At present, the domestically produced PB pipeline is made of polybutylene (PB) produced by BaSELL of the Netherlands and Shell of the United States. The production and inspection of the products are strictly implemented in the national standard GB/T19473.1- 2004 requirements.
PB pipe product features
First, light weight, good flexibility, simple construction: PB pipe weight is 1 / 20 of galvanized steel pipe, easy to handle, the minimum bending radius is 6D. Second, the durability is good, non-toxic and harmless: due to its high molecular weight, stable molecular structure, in the absence of ultraviolet radiation, the service life is not less than 50 years, and it is non-toxic and harmless. Third, anti-freeze heat resistance: under the temperature of minus 20 ° C, has a good low temperature impact resistance, the pipe will not freeze crack. After thawing, the tube can be restored to its original condition; at 82 ° C, all aspects of performance remain very good. Fourth, the pipe wall is smooth, no scaling: the inner wall is smooth, compared with the galvanized pipe, can increase the water flow by 30%. 5. Advanced connection method: The connection mode is integrated hot-melt connection, so when the battery is buried, the movement of the pipe and the leakage of the joint due to temperature change and water hammer phenomenon can be avoided. Sixth, easy to repair: When the PB pipe is buried, it will not be bonded to concrete. In the event of man-made damage, quick repairs can be made through replacement piping.
Main application areas of PB pipeline
1. Hot and cold water pipes for tap water: pipes for direct drinking water engineering. Second, heating pipe: can be used to connect radiators and other high-temperature heating systems, but also for floor, wall radiant heating and other low-temperature heating systems and air conditioning piping systems. Third, solar residential warm water pipes: used for warm water and heating pipes in solar homes. 4. Tubes for melting snow: Suitable for heating pipes for deicing and snowing under roads and parking lots. V. Industrial pipe: Because the material is resistant to chemical corrosion, non-toxic and tasteless, it can be used in chemical engineering, food processing and industrial water.
PB pipe connection technology PB pipe can be hot-melt connected, heated by special equipment, and pressed by hand or mechanically. This connection method avoids the leakage problem of the metal pipe connection, and the construction is convenient, safe and reliable.
Oxygen-blocking polybutene (PB) pipe
In the field of HVAC, PB pipes have superior properties unmatched by other plastics. However, the oxygen permeability of the polybutene pipe is slightly higher, and the oxygen in the hot water pipe is liable to corrode the metal pipe fittings and the like in the system, and is more disadvantageous for the high temperature heating system that connects the metal radiator. In addition, although the inner wall of the pipe is smooth and ensures no scaling, it has been proved that after 3 to 5 years of use, a very thin layer of biological slime adheres to the inner wall of the pipe, and after the layer of mud completely covers the pipe wall, the pipe wall It will speed up the diameter reduction, the water resistance is large, the water flow is sharply reduced, and the pipeline will be blocked for a long time. In addition, the cleaning of the pipeline is difficult, and it can only be cleaned by mechanical means, and other methods such as chemical methods cannot be cleaned. This is because the oxygen in the water causes the microbes to multiply, and the high oxygen permeability of the pipes means that the pipes will breathe and encourage the microbes to multiply. A large amount of dead microorganisms accumulate to form a biological slime. Therefore, oxygen barrier technology must be used to inhibit the proliferation of microorganisms, thus ensuring the safe use of pipelines.
There are currently two oxygen barrier PB pipes on the market, which use a very thin (only about 10 wire) ethylene-vinyl alcohol copolymer (EVOH) resin layer as the oxygen barrier layer. One is a three-layer co-extruded oxygen barrier PB tube, that is, a layer of hot melt adhesive and EVOH resin layer is uniformly coated outside the PB pipe. Because EVOH resin is easier to absorb moisture and the oxygen barrier capacity of EVOH resin after moisture absorption is greatly reduced, and the surface will be scratched during construction, the oxygen barrier effect will be reduced; the other is a five-layer co-extruded oxygen barrier PB tube. From the inside to the outside is PB-hot melt adhesive-EVOH-hot melt adhesive-PB, in which the inner layer PB is thicker, it plays a role of pressure, and the outer layer PB is thin, which plays a protective role. It is not difficult to see that this The pipeline is ideal, but the processing is difficult and the equipment cost is high.
LED downlights are a popular choice for modern lighting designs, offering efficient and effective solutions for both residential and commercial spaces. These small and compact lights are perfect for tight spaces and offer flexibility in installation and design. Mini downlights are even smaller versions, perfect for adding subtle touches of light to specific areas. Adjustable downlights are popular for their ability to change the direction and focus of the light, making them perfect for highlighting artwork or specific features within a space. Trimless versions of downlights offer a minimalist and sleek look, without any visible trim or bezels. With their versatility and energy efficiency, LED downlights are becoming an increasingly popular lighting choice for contemporary and stylish spaces.
Small Downlights ,Mini Downlights ,Adjustable Downlights,Trimless Downlights
Ningbo Le Monde Lighting Co.,Ltd , https://www.nblemonde-lighting.com