The reason of PVC profile yellowing
The reason of PVC profile yellowing
(China petrochemical co., LTD., ciru branch, shandong zibo 255400)
[abstract] the test used in the production of material (NCM) and section B (color yellow) of the original whiteness of PVC resin, aging whiteness, thermal stability time, molecular weight and its distribution and the degree of gelation of profiles, profiles B, the results show that: (1) compared with section A, B for the production profile of original whiteness of PVC resin, aging whiteness, thermal stability time, molecular weight and its distribution are qualified; The gelation degree of the outer wall of section B is about 10% higher than the outer wall of section A, indicating that the temperature of the die is high when extruded section B is high, thus the color of the profile B is yellow. In addition, simulation tests are carried out to verify the analysis results.
[keywords] PVC profiles; DSC; Gelation degree
[Chinese map classification code] TQ325.3 [document code] A [article number] 1009-7937(2009)04-0015-03
The type of PVC resin produced by the company of the s-1000 type PVC resin (ethylene method) is used for the production of 1225, and the PVC resin produced by the same manufacturer is normal. To find out the reason, to guide the company's production, the author except for regular inspection, also USES (DSC), differential scanning calorimeter analysis the gelation of PVC profile, analyzes the problems of the company. The test method of gelation is X - ray diffraction, capillary flow variation and DSC method. The author adopts DSC method, which is less dependent on formula and is a potential method [1].
1 test section
1·1 main raw materials
Samples taken at the company site: 1220, 1225 batches of PVC resin; The section B (color yellow) produced by 1225 batches of PVC resin.
Compound lead salt stabilizer: German bear brand; Active calcium carbonate: changzhou calcium carbonate co., LTD. CPE 135A: weifang yaxing chemical co., LTD. ACR401: zibo huaxing auxiliary co., LTD. Titanium white powder: dupont China group co., LTD. Calcium stearate: zibo new plastic chemical co., LTD. Paraffin and stearic acid are sold in cities.
1·2 profile formula
PVC: 100, composite lead salt stabilizer: 6· 0, active calcium carbonate: 30, CPE 135A: 11, ACR401:2· 5, titanium white powder: 4· 0, stearic acid calcium, paraffin, stearate lubricant, etc.
1·3 test equipment
DSC: 2910, American TA company; Electric drying oven: DGF 3006a, chongqing test equipment factory; Whiteness meter: WSB-2 type, wenzhou instrument instrument factory; Alliance liquid chromatograph: American Waters.
2 results and discussion
2·1 whiteness and thermal stability time
The author according to the GB/T 5761-1993 "universal PVC resin suspension method" in appendix B white degree of the aging test method, 1220, 1225 batches of PVC resin for the whiteness measurement before and after aging, according to the GB/T 2917-1987 "PVC thermal stability measurement method --, Congo red method and the act of pH testing the thermal stability of PVC resin
