PVC resin supplier
Gandi Chemical Solutions supplies suspension PVC resin — polyvinyl chloride, CAS 9002-86-2 — as a white free-flowing powder in three grades: SG3, SG5 and SG8. The grade is chosen by K-value, and K-value is chosen by what the finished part has to do rather than by what the resin costs.
Grades held
3 grades of polyvinyl chloride, CAS 9002-86-2. Each one links to its full specification, safety data and packaging.
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SG3 — high viscosity
K-value 71–73
High molecular weight: better mechanical strength, higher elongation, and a much greater capacity to absorb plasticiser without becoming sticky. The grade flexible compounds are built on.
View the specification
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SG5 — standard
K-value 66–68
The general-purpose workhorse, also designated PVC1091, with a degree of polymerisation around 1000–1100. Most rigid extrusion and injection moulding is built around it.
View the specification
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SG8 — low viscosity
K-value 55–59
Low molecular weight, so lower melt viscosity and easier flow into thin sections and complex tooling — traded against reduced impact strength and lower elongation.
View the specification
What decides the grade
One resin, three molecular weights. Every difference below follows from that, and the specification that matters on the enquiry is the K-value rather than the SG number alone.
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Rigid or flexible
Rigid pipe, profile and fittings sit on SG5. Flexible compounds — cable insulation, hose, membrane, coated fabric — need SG3, because high plasticiser loading is exactly what a high-molecular-weight resin absorbs without going tacky.
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Flow against impact strength
SG8 flows into thin walls and tight tooling that SG5 will not fill cleanly, and it gives up impact strength and elongation to do it. Where flow is the problem, a processing change is sometimes the cheaper answer than a lower-molecular-weight resin.
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Plasticiser loading
State the phr you are targeting and the finished hardness. That pair confirms the grade before an order is placed, which is faster than proving it on a production line.
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Producer variation
The same nominal grade from different producers can vary enough in bulk density and porosity to change a formulation. Name the process — pipe, profile, injection, calendering — on the enquiry so the resin is quoted against it.
Supply, documentation and handling
Packaging
Bags and jumbo bags, packed to your requirement. Tell us how the resin is conveyed into the plant and the pack size is quoted to suit it.
Documentation
A safety data sheet ships with every consignment, and a certificate of analysis stating K-value and bulk density is issued on request.
Storage
Dry, off the floor and out of direct sun. PVC powder picks up moisture, and moisture in the feed is the usual cause of porosity and surface defects downstream.
How it is quoted
Priced by quotation. Send the K-value, the process and the monthly volume, and GCS confirms the grade against the application before quoting it.
Before you order pvc resin
Which PVC grade do I need for rigid pipe?
SG5, in almost every case. Its K-value of 66–68 balances melt processability against mechanical strength, which is the balance rigid extrusion is designed around. SG3 is for flexible compounds and SG8 for thin-wall parts that SG5 will not fill.
What is the K-value, and why does it decide the grade?
K-value is a measure of molecular weight read from solution viscosity. A higher K-value means longer polymer chains, which means more strength, more elongation and more plasticiser absorption — and a higher melt viscosity that is harder to push through tooling. Every other difference between SG3, SG5 and SG8 follows from it.
Will SG8 fix a flow problem?
Often, and it costs impact strength and elongation to do it. Before switching, tell us the part geometry and wall thickness — sometimes the answer is a processing or formulation change rather than a lower-molecular-weight resin.
Can I substitute the same grade from a different producer?
Not without checking. The same nominal SG number can vary in bulk density and porosity between producers, and that shows up as a formulation change rather than as a specification failure. Ask for the certificate of analysis and compare it against the resin you run now.
Still deciding between grades? Send the duty and the volume, and GCS comes back with what it costs and when it lands. Request a Quote
