How to improve the surface luminance of PVC special-shaped material

January 17, 2018

 

GB/T8814-2004 has specified the appearance quality of profiles. Although the specific values or grades of surface brightness have not been put forward, 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. In this paper, several main factors affecting the surface luminance of the profile are studied and analyzed.

 

Test part

1. Main test equipment

Cold and hot mixing unit, type SRL500-1000, Zhangjiagang plastic equipment factory, twin screw extruder, 65/132 type, Shanghai Jinhu extrusion equipment Co., Ltd., push and pull 80 frame molds, type 80, Jiangsu Jerry mould factory.

2. Main test materials

PVC, QS-1050P grade, CPE grade, Qilu Petrochemical; H135A Shandong, Weihai Chengdu production; production; lubricants, active calcium carbonate production in Jingxing, Shijiazhuang; Guangdong Shunde masterbatch production.

3. Test steps

Based on the 100 parts of the PVC resin, the test raw materials are accurately named according to the experimental formula. After mixing with the same process, the material is extruded continuously on the twin screw extruder - push and pull 80-K. In the test, the extrusion process is basically kept the same as the temperature of the machine barrel, 170~180 degrees C, the die temperature, and 180~190 degrees C. The influence of various factors on the surface luminance is discussed according to the surface luminance of the extruded profile.

Analysis and discussion of test results

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. [1]. The active calcium carbonate is a kind of commonly used filler in the production of profiles, whic

 

h affects the surface luminance of the profile.

It can be seen from table 1 that when the amount of activated calcium carbonate is 15 kg, the properties of the profiles are qualified and the surface luminance is better. When the dosage increased to 20kg, while the qualified product performance testing, but the surface brightness decreased significantly, 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].

Table 1 Effect of the amount of activated calcium carbonate on the surface luminance of the profile

 

 

Properties of surface luminance profiles on formula number activated calcium carbonate / profile surface

1# 15 is well qualified

2# 20 poor qualification

Note: the amount of PVC is 100 copies, the same below

The effect 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.

Table 2 Effect of the amount of PE wax on the surface luminance of the profile

Properties of luminance profiles on the surface of formula PE paraffin profile

3# 0.2 is poor qualified

4# 0.4 is better qualified

5# 0.6 poor disqualification

It can be seen from table 2 that when the amount of PE wax is 0.2 copies, the profile performance test is qualified, but the surface light brightness is poor. When the amount of its dosage is increased to 0.4 parts, the profile extrusion is well plasticized, the performance test is qualified and the surface is brighter. But when the amount of the material is increased to 0.6 parts, the extrusion of the material is difficult, the material is plasticized and the performance is not qualified. 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.

The effect of 3 and 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.

As can be seen from table 3, when the amount of ACR in the formula is 0.5. The surface luminance of the profile is poor, and the physical performance testing is also unqualified. This is because the amount of ACR is too small, so that PVC can not be well converted to the sticky wall. The material can not get enough shear stress and cannot be well plasticized. Therefore, the physical properties and surface brightness of profiles are poor. 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.

The effect of the amount of Table 3 ACR on the surface luminance of the profile

Performance of PE wax / profile surface profile

6# 0.5 is poor and unqualified

7# 1.5 is well qualified

8# 2.5 is slightly inferior

4. The surface quality of the die to the surface of the profile

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