The surface brightness of profiles has attracted more and more attention from customers. There are many factors affecting the surface luminance of the profile, and some factors restrict each other and complement each other.

Under normal circumstances, the factors affecting the surface brightness of PVC profiles are mainly the formulation raw materials, mold design and manufacturing, and the production process. The method of improving the surface brightness of PVC profiles is generally started from these three aspects:

1, optimize formula design to ensure the quality of raw materials

The ratio of stabilizers, processing modifiers and other additives in the formulation should ensure the good thermal stability and processing fluidity of PVC; the amount of lubricants (especially external lubricants) should be reasonable to reduce extrusion as much as possible.

2, from the mold design and manufacturing to ensure the surface brightness of the product

The flow path structure design of the machine head should ensure that the material flow rate of each part of the die section is as uniform as possible, the inner rib speed cannot be too different from the outer wall (generally not more than 15%), and the thickness should not exceed 2/3 of the outer wall thickness. 

3, reasonable adjustment of the extrusion process to improve the surface brightness of the product

In the actual production process, the process temperature, speed and pressure are adjusted in accordance with the plasticizing state of the material to ensure good plasticization of the material, and the mold temperature is appropriately increased on the basis of this. If a separate heating zone (typically about 10 mm long) is provided at the exit of the die forming section to independently control the temperature, it is more advantageous to increase the surface brightness of the article.

Below we detail the impact of three raw materials on surface luminance:

1. The influence of the amount of active calcium carbonate on the surface luminance of the profile

Packing is essential in the production of profile. It can reduce costs and improve some properties of profiles, such as decreasing the dimension change rate and increasing rigidity of profiles after heating, etc. The active calcium carbonate is a kind of commonly used filler in the production of profiles, which affects the surface luminance of the profile.This is because the active calcium carbonate oil absorption value is higher, adding too much, active calcium carbonate absorption profile formula of lubricant, thus reducing the surface brightness profile of .

2.PE wax on the surface luminance of the profile

PE wax is a more common external lubricant. In the process, under pressure, easily from the mixed material extrusion, shift analysis to the surface, arranged PE molecular orientation, polar groups to the metal surface by physical adsorption and chemical bonding, forming a layer of lubricant molecules, therefore, it can reduce the friction surface of the polymer and equipment, improve the optical surface brightness profile.This is because the lubricant is added too much, forming a layer of isolation film. There will be slipping phenomenon between the mixed materials and equipment. The material can not get the shear stress due to plasticization and cannot be well plasticized. Therefore, the profile performance is not qualified, and the surface brightness decreases. Therefore, the reasonable amount of lubricant is the key to ensure the properties of the profile and the surface light.

3.ACR on the surface luminance of profiles

As a processing auxiliary, ACR can improve the molding performance of hard PVC. Its addition can improve the friction coefficient between resin and machinery, make rigid PVC change from sliding wall to sticky wall, increase shear stress, and material is well plasticized, so that it will have good surface brightness.

 When the amount of ACR is increased, the material can get enough shear stress and good plasticization. Therefore, the physical properties and surface brightness of profiles are improved. However, the more ACR dosage is not better, because the addition of ACR can accelerate the process of material plasticization. If the material is plasticized prematurely, some material will be decomposed before the die is extruded, which will also reduce the brightness of the surface of the profile. Therefore, to find the appropriate amount of ACR and make it fit well with other auxiliaries, the surface and internal properties of the profile will be greatly improved.