Polyvinyl Chloride (PVC) Powder Coatings – Develop, Application, Supply
This paper discusses the development of polyvinyl chloride (PVC) powder coatings at home and abroad, introduces the basic formula, preparation technology and performance index of PVC powder coatings, and makes a necessary introduction to its application in the anti-corrosion and decoration of steel pipes.
Foreword
Powder coating is a kind of 100% solid powder. It is different from the general solvent-based coating and water-soluble coating, not to solvent or water as a dispersion medium, but with the help of air as a dispersion medium. In the past decade, the governments of the world to produce coatings factories and enterprises caused by environmental pollution increasing attention, strengthened the restrictions on the use of solvents. By the end of the eighties in Europe and the United States in the coating manufacturing, production, construction application are strictly restricted the use of solvents and emissions, some parts of the United States also in the form of laws promulgated the solvent use limitation law, the provisions of as many as 66 articles, and Europe and the United States put forward the “three E” objective:
(1) Ecology Modification
(2) Energy Saving
(3) Economic Benefit
In this context, powder coatings have experienced rapid development due to their pollution-free nature, high utilization of raw materials, and numerous advantages. Specifically in Western Europe and North America, the annual growth rate of powder coatings reaches 10%. Moreover, in recent years, China has also witnessed a remarkable annual growth rate of 100% for powder coatings.
Polyvinyl chloride (PVC) Powder Coatings are particularly favored by users due to their exceptional decorative properties as well as weather and corrosion resistance. Currently, PVC powder coatings are extensively applied in various fields including cable protection with steel pipe, chemical corrosion resistance pipe, sewer drainage pipe, pipes for petroleum and chemical industry, road signs, lighting poles, highway guardrail etc.
Development Process
1.Basic formula of PVC powder coating
PVC powder coating is made of PVC resin as the base material with plasticizer, stabilizer, filler and other additives. The basic formula is shown in Table (White color).
| PVC Resin | Proportion(%) |
| DOP | 7-10 |
| DOS | 6-8 |
| Heat Stabilizer A | 10-12 |
| Heat Stabilizer B | 8-10 |
| TiO2(B101) | 12-15 |
| CaCo3 | 5-6 |
| Anti-aging Agent | 0.8-1 |
| Pigment Phthalein Blue/ BS | Proper Amount |
2.Preparation Technology of PVC powder coating
The preparation method of PVC powder coating, its process is shown in Figure.
3.Product Performance Analysis Test Results
After repeated research and development, testing, and compared with imported products, some of the performance of PVC powder coating finally reached or even exceeded the performance of imported products of the same kind, see the table.
| Hardness(Shore Hardness A) | 83-84 |
| Tensile Strength(N/Mm2) | 10.7-11.93 |
| Ultimate Elongation (%) | 95 |
| Heat Stability(250C, 15min) | Dark Yellow |
| Specific Gravity(g/Cm3) | 1.3 |
| Bending Under Low Tempeteature(-40℃ ±2℃) | Intact |
| Melt Index( Small Bore, g/10min | 10.44 |
| Flowability | 1”38 |
| Oxygen Index Oi(%) | 25.0 |
| Smoke Output(%) | 6.32 |
Application of PVC Powder Coated Steel Pipe
PVC powder coating film is semi-hard thermoplastic state. Compared with polyethylene, the melting temperature and decomposition temperature difference is small, so when used must pay strict attention to baking temperature and time. Because of its poor adhesion, before dipping, generally need to be coated with a layer of primer to increase the adhesion of the coating.
1.The main properties of the coating
- PVC powder coating products include: indoor decoration materials and waterproof fabric, chemical tanks, floors, covering packaging film, garden hose and wire insulation.
- The processing methods adopt dry mixing, injection molding, extrusion hollow blow molding, calendering, and fluidized bed dipping.
- Flame retardant (added flame retardant)
- Water and chemical resistance, good aging resistance.
2.Main construction method and application range
PVC powder coating is mainly used in metal mesh, cold storage shed, steel furniture, steel pipe and so on. The coating process is mainly as follows:
(1) Pre-treatment: phosphate treatment – rust removal, phosphating.
(2) Primer coating: Dip the primer, after drying, the thickness of the primer film is 5-10μm,
(3) electrostatic spraying or fluidized bed dipping.
4. preheating temperature :230-290℃,10min, film thickness: 500um;
Or 290℃, 5min without preheating, film thickness 200um.
PVC coated steel pipe is useful in petrochemical anti-corrosion, useful in highway guardrail, useful in the pole, after many years of application results show that PVC coating water resistance, atmospheric aging resistance is good, generally available for more than 15 years, eliminate the trouble of brush paint often, comprehensive comparison of its low cost, used in chemical anti-corrosion, can also be used for more than five years, for the user to solve the anti-corrosion problem.
