PVC core foaming composite pipe
DATE：2022/6/2 9:01:22 / READ： / SOURCE：This station
PVC core foaming composite pipe
The development of UPVC drainage pipe has experienced solid wall drainage pipe, UPVC corrugated pipe and double wall corrugated pipe. Now it tends to vigorously develop UPVC foam pipe. Rigid PVC foam pipe with core layer is a new type of three-layer composite pipe. Two kinds of PVC resins with different relative molecular weights were co extruded with a special die. The extruded pipe wall was a hard and dense non foaming layer on the inner and outer skin, and the middle was a foam sandwich pipe with fine and uniform cell structure. Hollow plate production line wwww handern. com
The core layer in the middle of rigid polyvinyl chloride (UPVC) core layer foaming pipe is a foaming layer with a density of only 700~900kg/m3. The inner and outer layers are the same as the UPVC solid wall drainage pipe. For the whole pipe, the density is between 900~1100kg/m. Its own material consumption is low. The UPVC core foamed pipe with the same wall thickness is about 20%~30% lighter than the UPVC solid wall pipe. At the same time, it has good sound insulation and thermal insulation. It is especially suitable for building drainage, can significantly reduce the running water noise, and can be used for hot water transmission below 60 ℃. For this reason, UPVC core layer foam pipe has been more and more widely used in urban and rural building drainage projects. For the majority of users, UPVC is lighter than UPVC PV pipe, more convenient to install, and lower than UPVC (PVC) solid pipe. At present, the sales situation of rigid polyvinyl chloride (UPVC) core foamed pipe in the market is promising and has a bright future. Hollow plate production line wwww handern. com
1. raw material selection and typical formula
(1) Selection of PVC resin UPVC core layer foaming pipe is composed of three layers. The composition of the inner and outer layers is the same, which is similar to the material of UPVC solid wall pipe. The middle foaming layer needs to be foamed. For the solid wall layer and foaming layer, the selection of PVC resin models is also different. The national standard gb/t16800-1997 stipulates that the inner and outer solid wall layers must have good mechanical properties, such as tensile strength not less than 43mpa. Therefore, when selecting the internal and external solid wall layer resin, both the processability and the mechanical properties of the resin should be considered. The high molecular weight resin has good mechanical properties, but poor processability; Although low molecular weight resin has good flow processability, some mechanical properties are poor; PVC resin with medium molecular weight has good processability and mechanical properties, which can meet the needs of pipe production.
The choice of resin type is very important, which has a great impact on the subsequent composite extrusion. Loose PVC resins with polymerization degree of about 1000, such as SG4 and SG5, are generally used for the inner and outer skin of UPVC core foaming pipes. This type of resin is suitable for making high-strength hard pipes and profiles. The intermediate layer is required to be a foam core layer with fine and uniform cell structure. During the molding process, the resin needs good fluidity. When the foaming agent is decomposed into gas, the resin is easy to form bubbles. Therefore, it is better to use a resin with a relative molecular weight slightly lower than SG6 resin, which can meet the process requirements and facilitate composite extrusion.
(2) Additive selection hollow plate production line wwwwww handern. com
① Stabilizer must be added in the processing of UPVC. The processing temperature of UPVC is generally lower than its decomposition temperature. In order to inhibit the decomposition of UPVC resin at the processing temperature, a certain amount of heat stabilizer must be added. At present, most stabilizers used in the production of drainage pipes are lead salts, such as tribasic lead sulfate (tribasic salt) and dibasic lead phosphite (dibasic salt), and rare earth composite heat stabilizers (REC) are also used. Comparatively speaking, whether it is thermal stability effect, synergistic effect, internal moisture effect, etc., the latter is better than the latter. In addition, the composite salt selling stabilizer, which is developing rapidly, has both thermal stability and wetting capacity. Compared with the general powdered lead salt, it is convenient and dust-free. It is very suitable for the use of rigid PVC drainage pipes.
2 working agents and modifiers in order to improve the working and impact properties of PVC, it is often necessary to add some processing aids and modifiers. Common processing aids, such as the pressure resistance and impact resistance of two field ester 11 lifting pipes, often need to add impact modifiers, such as oxidized polyethylene glycol (CPE), ethylene vinyl acetate copolymer (VA) methylpropionase, diene, styrene copolymer m, with uniform and fine bubble holes. Resin modifiers, such as ABS, EVA, etc., are often added, CPE is the most suitable modifier for the production of UPVC core foaming drainage pipe, which has the advantage of Wumart. Hollow plate production line wwww handern. com
③ When the blowing agent is used to produce UPVC core layer foaming pipes, the chemical foaming method is used for the core layer foaming, and the common Azodicarbonamide (AC) is selected as the blowing agent, with small dosage and large gas evolution. The above two kinds of heat stabilizers have the function of activating foaming agent. It can reduce the decomposition temperature of AC foaming agent from 200 ℃ to 160~180 ℃, which is close to the melting temperature of resin, and can decompose rapidly within a narrow temperature range. In this way, the foaming efficiency is high and the product quality is good.
④ Filler in the processing of UPVC, it is often necessary to add an appropriate amount of filler. The first purpose is to improve the stiffness, hardness or some mechanical properties of materials; Second, reduce the cost, but do not add excessive fillers in order to reduce the cost. When processing UPVC pipes, the filler calcium carbonate is generally added, which is of good quality and low price, with a wide range of sources, and the dosage is no more than 30 parts.
⑤ In the deep processing of UPVC, the PVC resin turns yellow due to the degradation reaction of PVC. The PVC produced has a good system. To improve the appearance of products, it is often necessary to add some pigments to increase the whiteness of materials, such as titanium dioxide, fluorescent brighteners, etc. For different UPVC products, the dosage is different and must be
Treat them separately. two hundred and thirty-nine
⑥ Other additives, such as lubricants, are the same as the production of ordinary pipes.
The development of UPVC drainage pipe has experienced solid wall drainage pipe, UPVC corrugated pipe and double wall corrugated pipe. Now it tends to vigorously develop UPVC foam pipe. Rigid PVC foam pipe with core layer is a new type of three-layer composite pipe. Two kinds of PVC resins with different relative molecular weights were co extruded with a special die. The extruded pipe wall was a hard and dense non foaming layer on the inner and outer skin, and the middle was a foam sandwich pipe with fine and uniform cell structure. Hollow plate production line wwww handern. com
The core layer in the middle of rigid polyvinyl chloride (UPVC) core layer foaming pipe is a foaming layer with a density of only 700~900kg/m3. The inner and outer layers are the same as the UPVC solid wall drainage pipe. For the whole pipe, the density is between 900~1100kg/m. Its own material consumption is low. The UPVC core foamed pipe with the same wall thickness is about 20%~30% lighter than the UPVC solid wall pipe. At the same time, it has good sound insulation and thermal insulation. It is especially suitable for building drainage, can significantly reduce the running water noise, and can be used for hot water transmission below 60 ℃. For this reason, UPVC core layer foam pipe has been more and more widely used in urban and rural building drainage projects. For the majority of users, UPVC is lighter than UPVC PV pipe, more convenient to install, and lower than UPVC (PVC) solid pipe. At present, the sales situation of rigid polyvinyl chloride (UPVC) core foamed pipe in the market is promising and has a bright future. Hollow plate production line wwww handern. com
1. raw material selection and typical formula
(1) Selection of PVC resin UPVC core layer foaming pipe is composed of three layers. The composition of the inner and outer layers is the same, which is similar to the material of UPVC solid wall pipe. The middle foaming layer needs to be foamed. For the solid wall layer and foaming layer, the selection of PVC resin models is also different. The national standard gb/t16800-1997 stipulates that the inner and outer solid wall layers must have good mechanical properties, such as tensile strength not less than 43mpa. Therefore, when selecting the internal and external solid wall layer resin, both the processability and the mechanical properties of the resin should be considered. The high molecular weight resin has good mechanical properties, but poor processability; Although low molecular weight resin has good flow processability, some mechanical properties are poor; PVC resin with medium molecular weight has good processability and mechanical properties, which can meet the needs of pipe production.
The choice of resin type is very important, which has a great impact on the subsequent composite extrusion. Loose PVC resins with polymerization degree of about 1000, such as SG4 and SG5, are generally used for the inner and outer skin of UPVC core foaming pipes. This type of resin is suitable for making high-strength hard pipes and profiles. The intermediate layer is required to be a foam core layer with fine and uniform cell structure. During the molding process, the resin needs good fluidity. When the foaming agent is decomposed into gas, the resin is easy to form bubbles. Therefore, it is better to use a resin with a relative molecular weight slightly lower than SG6 resin, which can meet the process requirements and facilitate composite extrusion.
(2) Additive selection hollow plate production line wwwwww handern. com
① Stabilizer must be added in the processing of UPVC. The processing temperature of UPVC is generally lower than its decomposition temperature. In order to inhibit the decomposition of UPVC resin at the processing temperature, a certain amount of heat stabilizer must be added. At present, most stabilizers used in the production of drainage pipes are lead salts, such as tribasic lead sulfate (tribasic salt) and dibasic lead phosphite (dibasic salt), and rare earth composite heat stabilizers (REC) are also used. Comparatively speaking, whether it is thermal stability effect, synergistic effect, internal moisture effect, etc., the latter is better than the latter. In addition, the composite salt selling stabilizer, which is developing rapidly, has both thermal stability and wetting capacity. Compared with the general powdered lead salt, it is convenient and dust-free. It is very suitable for the use of rigid PVC drainage pipes.
2 working agents and modifiers in order to improve the working and impact properties of PVC, it is often necessary to add some processing aids and modifiers. Common processing aids, such as the pressure resistance and impact resistance of two field ester 11 lifting pipes, often need to add impact modifiers, such as oxidized polyethylene glycol (CPE), ethylene vinyl acetate copolymer (VA) methylpropionase, diene, styrene copolymer m, with uniform and fine bubble holes. Resin modifiers, such as ABS, EVA, etc., are often added, CPE is the most suitable modifier for the production of UPVC core foaming drainage pipe, which has the advantage of Wumart. Hollow plate production line wwww handern. com
③ When the blowing agent is used to produce UPVC core layer foaming pipes, the chemical foaming method is used for the core layer foaming, and the common Azodicarbonamide (AC) is selected as the blowing agent, with small dosage and large gas evolution. The above two kinds of heat stabilizers have the function of activating foaming agent. It can reduce the decomposition temperature of AC foaming agent from 200 ℃ to 160~180 ℃, which is close to the melting temperature of resin, and can decompose rapidly within a narrow temperature range. In this way, the foaming efficiency is high and the product quality is good.
④ Filler in the processing of UPVC, it is often necessary to add an appropriate amount of filler. The first purpose is to improve the stiffness, hardness or some mechanical properties of materials; Second, reduce the cost, but do not add excessive fillers in order to reduce the cost. When processing UPVC pipes, the filler calcium carbonate is generally added, which is of good quality and low price, with a wide range of sources, and the dosage is no more than 30 parts.
⑤ In the deep processing of UPVC, the PVC resin turns yellow due to the degradation reaction of PVC. The PVC produced has a good system. To improve the appearance of products, it is often necessary to add some pigments to increase the whiteness of materials, such as titanium dioxide, fluorescent brighteners, etc. For different UPVC products, the dosage is different and must be
Treat them separately. two hundred and thirty-nine
⑥ Other additives, such as lubricants, are the same as the production of ordinary pipes.
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