PVC Resin Products: SG-5, SG-3, SG-7, SG-8
Four standard suspension grades, held and shipped out of Shandong, China. Between them they cover almost every enquiry we receive: pipe and profile at the top of the volume, soft plasticised products at the other end, and the low-viscosity grades for sheet, bottle and thin-wall work. 25 kg bags, jumbo bags or palletised; FCL and LCL.
Below is the decision logic, the full requirement figures for all four grades, and what we will and will not put our name to.
PVC Resin SG-3
SG-3 suspension PVC resin, K 71-72, viscosity number 127-135 mL/g. The GB/T 5761-2018 figures, plus what soft-product lines buy it for.
PVC Resin SG-5
SG-5 suspension PVC resin, K 66-68, viscosity number 107-118 mL/g. The GB/T 5761-2018 figures in one table, and what to send us for a firm offer.
PVC Resin SG-7
SG-7 suspension PVC resin, K 60-62, viscosity number 87-95 mL/g. The GB/T 5761-2018 figures, plus why rigid sheet and bottle lines buy it.
PVC Resin SG-8
SG-8 suspension PVC resin, K 55-59, viscosity number 73-86 mL/g. The GB/T 5761-2018 figures, plus why transparent sheet and foam lines buy it.
1. Which grade do you need
Grade selection is almost never ambiguous once you know the end product and the process. The K value follows from those two.
| Your end product | Process | Grade | Why |
|---|---|---|---|
| Water and drainage pipe, conduit, irrigation pipe | Extrusion | SG-5 | Molecular weight in the middle: fuses well enough to pass pressure and impact tests, flows well enough for output |
| uPVC window and door profiles, panels, fencing | Extrusion | SG-5 | Holds dimensional tolerance through cooling without demanding an unworkable torque |
| Pipe fittings, valves, electrical boxes | Injection | SG-5, or SG-7 on thin walls | SG-5 covers normal wall sections; thin and long-flow parts need the lower viscosity |
| Cable insulation and sheathing | Extrusion | SG-3 | The highest plasticiser absorption in the range, built for a heavily plasticised formulation |
| Flexible film, artificial leather, hose, footwear | Calendering, extrusion, moulding | SG-3 | Flexibility and low-temperature performance in the finished article |
| Rigid and transparent sheet, calendered film | Calendering, extrusion | SG-7, or SG-8 for the thinnest and clearest | Low melt viscosity gives clean roll release and even die filling |
| Bottles, containers, packaging | Blow moulding, thermoforming | SG-7 | Fills thin walls at low pressure and at a lower melt temperature |
| Foam board, shrink film, thin-wall transparent parts | Foam extrusion, injection, film | SG-8 | The furthest flow and the lowest gel level of the four |
If your product is not on this list, send us the end product and the process and we will tell you which of the four we would ship, including when the answer is that none of them is right.
2. The four grades, side by side
| Property | SG-3 | SG-5 | SG-7 | SG-8 |
|---|---|---|---|---|
| K value | 71 – 72 | 66 – 68 | 60 – 62 | 55 – 59 |
| Viscosity number (mL/g) | 127 – 135 | 107 – 118 | 87 – 95 | 73 – 86 |
| Average degree of polymerisation | 1251 – 1370 | 981 – 1135 | 741 – 845 | 650 – 740 |
| Apparent density (g/mL) | ≥ 0.45 | ≥ 0.48 | ≥ 0.50 | ≥ 0.50 |
| Plasticiser absorption (g per 100 g) | ≥ 26 | ≥ 19 | ≥ 12 | ≥ 12 |
| Fish eyes (per 400 cm²) | ≤ 20 | ≤ 20 | ≤ 30 | ≤ 30 |
| Volatile matter incl. water (%) | ≤ 0.30 | ≤ 0.40 | ≤ 0.40 | ≤ 0.40 |
| Typical application | Cable, film, artificial leather, hose | Pipes, fittings, profiles, rigid sheet | Rigid sheet, bottles, calendered film, injection | Transparent sheet, foam board, pipe fittings, injection |
What matters is the relationship between the numbers. As the K value falls from SG-3 to SG-8, viscosity number and polymerisation fall with it, and apparent density rises. That is the whole design of the system: higher molecular weight buys strength and plasticiser capacity, lower molecular weight buys flow and packing density.
The other thing to notice is how wide the bands are. SG-5 spans a viscosity number of 107 to 118, and SG-8 spans 73 to 86. Two deliveries can both be "SG-5" and behave differently in the same extruder. This is why we ask for the position in the band on every enquiry, and why quoting only a grade name leaves a specification open that later becomes somebody's reject rate.
3. What these figures are, and what they are not
They are the band requirements from GB/T 5761-2018. They define the range a conforming batch has to sit inside. What a specific delivery measured is on that delivery's certificate. The batch's own measured values are on its certificate.
The batch certificate comes from the producing plant. We are a first-tier distributor, not the plant that polymerises the resin. Each lot has a certificate issued by the plant's laboratory. Tell us at enquiry stage and we will obtain the certificate for the lot we are actually offering and send it to you before you commit, so you are deciding against a measured figure, not a marketing table.
We do not re-type certificates and present them as ours. If you need the COA for the lot on the water before you release the balance payment, that is a normal request and you should make it.
Watch the standard edition on the contract. GB/T 5761-2018 remains in force; the official record shows it was reviewed on 1 July 2025 and continued. The standards that govern designation and test methods, GB/T 3402.1-2026 and GB/T 3402.2-2026, take effect on 1 February 2027 in place of the 2005 and 2010 editions. What is confirmed and what a buyer should check is written up here.
4. Grades beyond these four
SG-5, SG-3, SG-7 and SG-8 are what we hold as standing grades, and they account for nearly every order we ship. They are not the limit of what we can source.
Other suspension grades (SG-4, SG-2, SG-1 and SG-6) can be sourced through the same channel. Paste resin (emulsion and micro-suspension) is available on request. Give us the grade and the application and we will confirm availability before quoting, rather than promising a lot we have not located.
We also have channels for CPVC, PE, PP and HDPE and can put them in the same enquiry. That side is smaller for us, and we say so up front.
5. How to enquire
Every enquiry that turns into a clean order has the same six things in it:
- The grade, and the position in the band: not "SG-5" but "SG-5, viscosity number 112–118".
- The end product and the process: what you make and how you make it.
- The quantity: first order and expected monthly volume.
- The packaging: 25 kg bags, jumbo bags, palletised, or your own bag design.
- The discharge port: name it and we quote FOB, CFR or CIF against it.
- The documents and the payment terms: so the figure we put in front of you is the cost of the order.
How to read the markings on a PVC resin bag is worth ten minutes before your first delivery arrives, and the grade comparison article is worth reading if you are still deciding between two of them.
Get a firm offer for this grade
Send the end product, the position in the band you need, the quantity and the discharge port. We will come back with a dated offer and the COA for the lot we are offering.