PVC transparent hose is made of polyvinyl chloride resin to a large number of plasticizers, a certain amount of stabilizers and other additives, the extrusion made in the system. It is widely used in construction, chemical industry, home for water infusion, transport corrosive media, also used as wire casing and wire insulation layer. It is widely used in construction, chemical industry,
PVC transparent hose formulations include pvc resin, heat stabilizer, lubricants, plasticizers and colorants. According to the above technical indicators analysis, formula design should meet the requirements of transparency, moderate hardness, high strength. To improve the transparency, in the choice of processing accessories, as far as possible with the refractive index and pvc resin refractive index (1) the same or similar additives. Because the refractive index of the same or similar raw materials processed into a homogeneous mixture, the refractive index is also similar to the refractive index of raw materials. So that in the direction of the incident light scattering phenomenon will not increase, so the product will not increase the turbidity, the transparency of the product will not be much affected.
PVC resin: the plasticizer in the preparation of a larger dose, so the pvc resin oil absorption is good, should choose loose type resin. At the same time require high brightness of resin, good thermal stability. The number of impurities and the number of fish eyes less batches. Under the premise of meeting the requirements of mechanical properties, the production of pvc transparent hose should be used as low as possible relative molecular weight resin. Because commonly used plasticizers dop and dbp often contain relatively low molecular weight components, when the processing temperature is higher than 105 ℃, often volatile and the formation of bubbles, the temperature can only be low control. In this case, the resin with a relatively low molecular weight has a higher degree of plasticization than the resin with a relatively large molecular weight, which contributes to the improvement of the transparency of the product. In addition, relatively low molecular weight resin is also easy to process. General PVC-SG3, SG4, SG5 resin can be, according to product requirements.
Plasticizer: the main consideration of its plasticizing effect, cold resistance, durability and transparency of the impact of PVC and so on. DOP is a comprehensive performance of a better plasticizer, refractive index of 1.484, and PVC refractive index (1.52 ~ 1.55) close. Commonly used as the main plasticizer for PVC transparent hose. DBP refractive index of 1.492, the same close to the PVC resin refractive index, will not have too much impact on transparency, but its growth efficiency is poor, and volatile, generally as a DOP-assisted plasticizer. To improve the cold resistance, can be added as a secondary plasticizer DOS. The amount of plasticizer is generally 40 to 55 parts.
Heat stabilizer: In addition to the requirements of heat resistance, weather resistance and ease of processing and other basic properties, but also should focus on its transparency. Organic tin stabilizer is the most ideal of PVC transparent products, the most commonly used heat stabilizer, but the price is higher. Metal soap stabilizers, such as calcium stearate, barium stearate, zinc stearate, are heat stabilizers commonly used in P V C transparent hoses. The composite products Ca / Zn, Ba / Zn, Ba / Ca and Ba / Ca / Zn is more ideal. The actual formula to reduce the amount of organic tin, while the choice of good transparency and both lubrication of calcium stearate (calcium soap) and zinc stearate (zinc soap) as an auxiliary stabilizer.
Antioxidant Phosphoric acid vinegar and epoxy oil with plastic and thermal stability, good transparency and low cost, can reduce the amount of organic tin, to reduce the processing of late dyeing process has a very good role, and with the hard Calcium stearate and zinc stearate have a synergistic effect on the stability of the formulation system has a positive contribution.
Lubricants: can be divided into two kinds of internal and external lubricants. In the P V C transparent hose, due to the larger amount of plasticizer, the viscosity of the material is relatively small, good fluidity, so the amount of lubricant less, the amount of 0.1 to 1.0 copies. General use of metal soaps, such as CaSt, BaSt, ZnSt, PbSt (PbSt the amount of control in the 0.1 or so, such as excessive use of the product will affect the transparency) and so on. Commonly used transparent lubricants are: paraffin, polyethylene wax, stearic acid, stearate and so on.
Colorants: more objective should be the color filler, due to the special nature of the PVC molecular structure, in the process of heat and mechanical friction, even if the addition of a sufficient stabilizer, will also be a certain degree of yellowing. Add a little pigment to cover up the yellow, make the product more beautiful. Commonly used colorants are ultramarine, phthalocyanine blue and brightener.