1、PVC inspection of raw materials
The quality of raw materials directly affects the performance of the profiles and the quality of the finished doors and windows，Therefore, the choice of raw materials、testing,、warehousing and use of such links should be checked
1-1、Selection of PVC raw materials
According to the requirement of product formulation，Production capacity of PVC raw material suppliers、Delivery capability、product quality、Reputation and quality assurance system for investigation、Analysis，Selection of large, quality assurance manufacturers
1-2、Inspection of raw materials
In accordance with national standards, industry standards, enterprise standards, various raw materials testing items and methods
1-2-1、Detection of PVC
PVC is the main raw material，Linking all kinds of PVC auxiliaries，And give the specific properties of PVC Profiles,Often choose PVC - SG5(SUPER GRADE), that is the average degree of satisfaction is about =1000, and the K value is 67,To make the parts glass temperature (Tg) moderate, hot forming processing suitable, good mechanical properties, low temperature resistance. The molecular weight, viscosity number, {(ml/g), (g/ml)}, resin particle size and distribution, residue, volatile content and impurity particle number of PVC resin were tested.
1-2-2、Detection of Titanium dioxide (TiO2)
Rutile titanium dioxide is the ideal coloring agent for white plastic windows，It also has the function of shielding ultraviolet rays (UV) and infrared rays，It can improve the weather resistance and heat resistance of parts，Rutile type titanium dioxide is a cube structure, titanium and oxygen atoms arranged closely, the crystal structure is stable, high density (4.26/cm3), refractive index, titanium dioxide particle size influence the surface quality of the products, mechanical impurities in titanium dioxide, during melt processing can accelerate the catalytic dehydrogenation, PVC. The dehydrogenation reaction caused by PVC degradation and discoloration. Therefore, the mechanical impurities, sieve residues, appearance and volatile content of titanium dioxide should be taken as important quality standards.
1-2-3、Detection of chlorinated polyethylene (CPE 135A)
CPE is a PVC impact modifier，The addition of CPE is designed to enhance the impact resistance of rigid PVC profiles and resist external force damage during the installation and use of doors and windows. CPE does not contain double bonds in its molecular structure. Good weatherability and good stability of light and heat for PVC profile. The presence of hydrogen atoms makes CPE polar and increases the compatibility with PVC. The miscibility depends on the chlorine content in the CPE and the distribution of chlorine atoms on the PE backbone (represented by residual crystallinity). As a modifier of PVC, CPE with chlorine content of 36%-38% is good. It not only has good elasticity and compatibility, but also has low crystallinity, low glass transition temperature and good comprehensive properties. The main test items are chlorine content and residual crystallinity, apparent density, tensile strength, volatile content, decomposition temperature, etc..
1-2-4、Determination of light calcium carbonate (CaCO3)
In order to reduce costs, improve rigidity and heat resistance, improve weather resistance, increase dimensional stability and be favorable for extrusion and molding, a certain amount of lightweight CaCO3 is often added. The content of CaCO3 in light calcium carbonate residue on sieve fineness, has an important influence on the physical and mechanical properties of products and product appearance, it is the main index, the second test appearance, volatile content, acid insoluble content have requirements.
Concluding remarks：Production enterprises must strengthen the management system, establish and improve the quality management system, strictly implement the relevant standards of the state or enterprises, and strive to improve product quality and achieve sustainable and healthy development of the industry
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