PVC Resin

1. What is PVC resin?

PVC resin, with the full name of polyvinyl chloride resin, is a kind of synthetic plastic polymer with large production volume each year. As a result, it is widely used in various plastic industrial fields. Polyvinyl chloride resin is a thermoplastic polymer compound formed by polymerization of vinyl chloride monomer(VCM) or dichloroethane(EDC) under the action of an initiator. Its main component is polyvinyl chloride. Meanwhile, adding some additives to enhance its heat resistance, toughness and ductility. Because of the characteristics of good chemical stability, corrosion resistance and water resistance, polyvinyl chloride is the most widely used raw material in plastic production. 

Before using PVC Resin to make finished products, we should convert it into compounds first by adding additives. As we all know, commonly used additives are heat stabilizers, UV stabilizers, plasticizers, heat modifiers, flame retardants, bactericides, foaming agents, etc.

2. What is PVC K value?

In brief, the K value is an index indicating the polymerization degree and molecular weight of polyvinyl chloride. In addition, the viscosity number is also an indicator of the molecular weight of the polymer. Since this product is an amorphous linear polymer compound, it is with various different characteristics. The larger the relatively molecular weight, the higher the viscosity, the better the strength, stiffness, toughness, heat and low temperature resistance of the material, but the worse the molding processability. On the whole, the difference in K value of polyvinyl chloride resin will have a certain impact on the processing technology and product performance. Therefore, when purchasing polyvinyl chloride resin, customers need to choose the suitable grade depends on the K value and applications.

By comparison, K70-75 PVC resin with high K value and higher molecular weight has the best mechanical properties. But it is more difficult to process.

In general, PVC resin k65/k66, PVC resin k67/k68 with suitable K value have a good balance between mechanical properties and processability. So they are the most popular and can meet the needs of the most PVC applications.

Compared to other types of PVC resin, K58-60 polyvinyl chloride with low value has the lowest mechanical properties and the processing is easiest. However, it has many difficulties in the application process.

3. What are the two main categories of PVC resin?

They are mainly classified into two categories based on particle morphology and plasticizer absorption:

Suspension PVC. The most common type, accounting for over 80% of total PVC production. Based on structure, it is further divided into “dense” and “loose” types. Loose PVC has more pores, easily absorbs plasticizers, has better processing performance, and is the most widely used.

Emulsion PVC. The particles are fine, often made into a paste, hence the name “PVC paste resin.” It is used for coating, impregnation, and slush molding processes, such as in the manufacture of gloves, artificial leather, and toys.

4. What are the main grades of PVC resin?

In China, general-purpose suspension PVC resin grades are represented by “SG” followed by a number, where S represents “suspension” and G represents “general-purpose.” The number represents the viscosity range. The higher the number, the higher the average degree of polymerization and the larger the molecular weight, usually resulting in higher product strength, but also increasing processing difficulty.

Internationally, the naming is usually directly linked to the average degree of polymerization, which is very intuitive. For example, S-1000 and S-1300 use internationally accepted naming conventions and refer to general-purpose suspension PVC resins used in rigid products. Different manufacturers may use different modeling systems, but the core is to reflect the resin’s average degree of polymerization and viscosity, which directly affects the product’s processing performance and final mechanical properties.

5. What is the difference between rigid PVC and flexible PVC?

The core difference lies in whether or not plasticizers are added.

Rigid PVC. No or very little (<10%) plasticizers are added. Products made from this type of PVC are rigid and have high strength, such as door and window profiles and water pipes.

Flexible PVC. High levels (up to 40% or more) of plasticizer are added. Products made from this material are soft and elastic, such as wire sheathing, inflatable toys, and hoses.

6. Can PVC be used for food packaging and medical supplies?

Yes, but under strict conditions. Food-grade or medical-grade PVC resin must be used. And all added additives (such as stabilizers and plasticizers) must meet the relevant hygiene standards.

7. How to improve the impact resistance of PVC resin?    

Virgin PVC, especially rigid PVC, has poor toughness. The most effective way to improve impact resistance is to add impact modifiers, most commonly chlorinated polyethylene and ACR. They significantly absorb impact energy, preventing brittle fracture of products.

8. What key information is needed when purchasing PVC resin?

Application Areas: Such as manufacturing pipes, profiles, wires, films, etc.

Processing Methods: Such as extrusion, injection molding, calendering, etc.

Product Requirements: Such as rigid or flexible PVC, whether there are special requirements such as food grade or weather resistance.

Target Model: If you have already determined the required model, please tell us directly, and we will provide you with a quote as soon as possible.

9. How to Quickly Select PVC Models by Applications?

1) Rigid Extrusion Products:

Door and window profiles, water pipes, chemical pipelines: SG-5, S-700.

High-strength rigid products: SG-4, S-1000 or higher polymerization degree models.

2) Injection Molded Products:

 Pipe fittings, valves, daily necessities: SG-7, S-600, S-800.

3) Flexible Products:

Wire and cable insulation layers, sheaths: SG-3, S-1000, S-1300.

Artificial leather, inflatable toys, and soft films: SG-3, S-1000, S-1300.

High-grade transparent soft products: Requires high resin purity and a high number of fish eyes; SG-3 is commonly used.

4) PVC Paste resin:

P-440, P-450 are used for coating (artificial leather, tarpaulins), dipping (gloves), and slush molding (toys).

10. What are the main types of PVC resin based on K value?

SG-3/K-65: High plasticizer absorption, mostly used in soft products such as cable materials, hoses, and flexible films.

SG-5/K-67: General-purpose mainstream grades, suitable for rigid products such as pipes, fittings, profiles, and sheets.

SG-7/SG-8/K-70: Better flowability and faster processing speed, mostly used in injection molded products and precision parts.

11. What are the main factors affecting the PVC resin price?

Upstream raw material costs: Fluctuations in the prices of ethylene, calcium carbide, liquid chlorine, electricity, and other energy sources.

Production process differences: The cost structures of the ethylene method and the calcium carbide method differ, resulting in different pricing.

Product grades: Prices increase progressively from general-purpose to high-transparency, food-grade, and medical-grade.

Supply and demand: Global plant operating rates, regional import demand, and seasonal demand changes.

Logistics and trade policies: Ocean freight, tariffs, exchange rate fluctuations, and regional trade barriers.

12. What about the delivery for your company’s PVC resin export orders?

Regular full container orders (1–10 containers): 3–7 working days after confirmation of prepayment and order details.

Large-volume long-term orders (500 tons or more): 7–10 working days depending on the production schedule.