Unsaturated Polyester Resin (UPR)
The versatile, general-purpose workhorse resin for FRP.
Review the official product data sheet for specifications and application information.
Samrat Poly Resins supplies Unsaturated Polyester Resin (UPR) to Indian B2B buyers as a category gateway for FRP and composite manufacturing. Start with the required product role, then review the specific grade data before selecting a resin.
Price
Price on Request
Industrial resin pricing varies based on:
- Order Quantity
- Resin Grade
- Current Raw Material Rates
Product details
| Minimum Order Quantity | 1,125 kg |
|---|---|
| Packaging | 225 kg Drum |
| Physical Form | Liquid |
| Colour / Appearance | Clear |
| Shelf Life | 3 months (225 kg drum) / 2 months (PET packaging) |
| Storage Temperature | 30–35 °C |
Technical specifications
| Resin Type | Orthophthalic Unsaturated Polyester Resin |
|---|---|
| Curing System | Non-accelerated |
| Viscosity | 350–450 cPs |
| Gel Time | < 8 minutes |
| Styrene Content | 33–40% |
| Specific Gravity / Density | Not part of the published specification for this grade |
| Cure Time | 45 minutes – 1.5 hours |
| MEKP Dosage | 1.5% |
| Cobalt Octoate Dosage | 0.4% |
| Purity | 99% |
Samrat Poly Resins manufactures Unsaturated Polyester Resin (UPR) at its facility in Doraha, Punjab, India. Established in 2017, the company operates an ISO 9001:2015 certified quality management system. UPR is a thermosetting resin widely used across the fibreglass-reinforced plastic (FRP) industry for its versatility and reliable mechanical properties. It crosslinks with styrene monomer through free-radical polymerisation, catalysed with MEKP, hardening into a rigid, durable composite. Polyester resins are broadly grouped into orthophthalic, isophthalic and vinyl ester families, differing in chemical resistance and cost. Samrat Poly Resins' standard UPR grade is a general-purpose orthophthalic resin — a clear liquid with 350–450 cPs viscosity, a gel time under 8 minutes and 99% purity — suited to hand layup, spray-up, moulding and everyday FRP work.
Samrat Poly Resins supplies this standard orthophthalic UPR grade under the product name GP Clear Resin, typically catalysed with an MEKP hardener and cobalt accelerator, then reinforced with glass fibre for hand layup and spray-up. For door and plywood lamination work, see our Lamination Resin; for higher chemical and corrosion resistance, step up to Vinyl Ester Resin; and pair with a Gelcoat Resin for a finished decorative surface.
Read the captions
- UPR is the category name many buyers search for.
- At Samrat Poly Resins, our standard orthophthalic UPR grade is supplied as GP Clear Resin. Our two data sheets share one reference: SPR-TDS-GCR.
- Our published data: 350–450 cPs viscosity, gel time under 8 minutes, 225 kg drums, 1,125 kg minimum order. Other suppliers’ grades differ.
What is Unsaturated Polyester Resin (UPR)?
Unsaturated Polyester Resin, commonly called UPR or polyester resin, is the broader resin category used in many FRP and composite applications. This page helps buyers start with that category, then move to the published Samrat product grade that matches the component, process and finished-product role.
The technical specifications and TDS on this page describe Samrat Poly Resins’ standard clear orthophthalic UPR, supplied as GP Clear Resin. Specialist products below have their own published data, packaging and suitability information; the standard UPR table should not be treated as their specification.
Types of unsaturated polyester resin
Unsaturated polyester resins are grouped by the acid in the polyester backbone, which is why a buyer usually chooses orthophthalic, isophthalic or terephthalic before choosing a grade. Samrat Poly Resins publishes these families, each with its own grades and data sheets.
| Family | Series | Published grades | Range |
|---|---|---|---|
| Orthophthalic Polyester Resins | SPR 201 | 18 | SPR 201 orthophthalic (ortho) unsaturated polyester resins made at Doraha, Punjab: general-purpose, casting, sheet, SMC/DMC, fire-retardant and gelcoat grades. |
| Isophthalic Polyester Resins | SPR 301 | 12 | SPR 301 isophthalic (ISO) polyester resins made at Doraha, Punjab, for water, chemical and outdoor service: tank-lining, filament-winding, SMC/DMC, rock-bolt and gelcoat grades. |
| Terephthalic Polyester Resins | SPR 401 | 4 | SPR 401 terephthalic polyester resins from Doraha, Punjab: SMC and DMC moulding-compound resins, a fire-retardant gelcoat and a heat-cured pultrusion grade. |
Vinyl ester is a separate resin class, listed under Vinyl Ester Resin. To start from the part you make, use FRP resin by job, or read the types of unsaturated polyester resin in more depth.
Key features
- Widely used, cost-effective orthophthalic UPR grade for general FRP work
- Clear liquid, 350–450 cPs viscosity for smooth reinforcement wet-out
- Gel time under 8 minutes for efficient production cycles
- Cures via MEKP and cobalt octoate at room temperature — no special curing equipment required
- 33–40% styrene content, 99% purity, consistent batch-to-batch quality
- Supplied in 225 kg drums, minimum order 1,125 kg
Applications
- Hand layup, spray-up and pultrusion
- FRP mouldings, panels and casting
- Bathware, automotive and marine composite parts
- General-purpose fiberglass fabrication
Choose the UPR grade by the product role
Use this as a starting point for enquiry and product-data review, not as a substitute for confirming process fit.
General FRP & clear GP work
Review GP Clear Resin for the published clear, general-purpose orthophthalic UPR grade used in common FRP processes.
Transparent-yellow GP work
Review GP Yellow Resin where its intentionally transparent-yellow supplied colour is acceptable in the required FRP build-up.
Door, plywood & FRP bonding
Review Lamination Resin for its published door-lamination, plywood-lamination and FRP-bonding applications.
Visible mould-side surface
Review GP Gelcoat Resin when the requirement is the mould-facing surface layer rather than the structural laminate.
Buttons & small decorative castings
Review Button Grade Resin for the published transparent casting role used for buttons and small decorative mouldings.
Specified fire-performance requirement
Review Fire Retardant Resin and its own published technical data when a project has a stated fire-performance requirement.
Chemical or corrosion resistance
Review Vinyl Ester Resin as the related alternative when the project specifies chemical- or corrosion-resistance requirements.
Separate epoxy system
Review the separate epoxy product data where a two-part epoxy system, rather than a polyester resin system, is specified.
