Isophthalic unsaturated polyester resin for laminates facing water immersion, chemical service or sustained outdoor conditions.
- Viscosity
- 500 cPs (mPa·s) at 25 °C
- Gel Time
- 15 minutes at 25 °C
Price on RequestTDS
Resin chemistry · SPR 301 series
Isophthalic Polyester Resins — SPR 301
Isophthalic polyester resin — "ISO resin" in the trade — is built on isophthalic acid rather than the phthalic anhydride of orthophthalic grades. The catalogue specifies the SPR 301 family where a laminate faces water immersion, chemical service or sustained outdoor conditions. Samrat Poly Resins manufactures the SPR 301 series at Doraha, Punjab, from a general isophthalic grade to lining, winding, moulding-compound, rock-bolt, fire-retardant and gelcoat grades.
In resin names, "ISO" means isophthalic chemistry. It is unrelated to ISO certification.
12Published
Grades
Grades
SPR 301 · 1 grade
General grade
SPR 301 · 2 grades
Tank-lining and anti-corrosive grades
Isophthalic grade with good electrical and heat-resistance properties, for the FRP lining of oil storage tanks.
- Viscosity
- 300–600 cPs at 25 °C
- Gel Time
- 15–35 minutes at 25 °C
Price on RequestTDS
Isophthalic grade with corrosion resistance against organic solvents and good chemical and heat resistance.
- Viscosity
- 200–400 cPs at 25 °C
- Gel Time
- 15–35 minutes at 25 °C
Price on RequestTDS
SPR 301 · 4 grades
Process grades
Isophthalic grade with high binding properties and high strength, for the filament winding process.
- Viscosity
- 200–400 cPs at 25 °C
- Gel Time
- 20–60+ minutes at 25 °C
Price on RequestTDS
Thixotropic isophthalic grade with heat, chemical and corrosion resistance and high strength.
- Viscosity
- 400–650 cPs
- Gel Time
- 15–35 minutes at 25 °C
Price on RequestTDS
Low-viscosity isophthalic grade designed for jute reinforcement.
- Viscosity
- 80–180 cPs at 25 °C
- Gel Time
- 40–90+ minutes at 25 °C
Price on RequestTDS
High-strength isophthalic liquid base resin used to manufacture rock-bolt anchoring compounds.
- Viscosity
- 2,000–3,500 cPs
Price on RequestTDS
SPR 301 · 2 grades
SMC and DMC grades
Two separate products sharing one typical specification in the catalogue.
SPR 301 · 1 grade
Fire-retardant grade
Halogen-free, ATH-filled isophthalic FR polyester resin.
- Viscosity
- 400 cPs
- Gel Time
- 5.5 minutes
SPR 301 · 1 grade
Gelcoat grade
Isophthalic polyester gelcoat, the grade normally specified where an FRP surface has to hold gloss and colour through weathering and water contact.
- Viscosity
- 40,000 cPs at 25 °C
- Gel Time
- 8 minutes at 25 °C
Price on RequestTDS
SPR 301 · 1 grade
Tooling grade — SPR 401 code range
SPR 401 TL carries an SPR 401 code but is an isophthalic NPG-based resin, so it is listed here and not with the terephthalic grades.
Highly reactive, high-molecular-weight isophthalic NPG-based polyester resin for composite mould production.
- Viscosity
- 400–650 cPs
- Gel Time
- 15–30 minutes at 25 °C
Price on RequestTDS
Isophthalic grades compared
Typical values from each grade's published data sheet, for shortlisting. They are not guaranteed properties of a finished part.
| Grade | Viscosity | Gel time | Data sheet |
|---|---|---|---|
| ISO Polyester ResinSPR 301 | 500 cPs (mPa·s) at 25 °C | 15 minutes at 25 °C | TDS |
| Oil Storage Tank Grade ResinSPR 301 OT | 300–600 cPs at 25 °C | 15–35 minutes at 25 °C | TDS |
| Organic Solvent-Resistant Grade ResinSPR 301 OS | 200–400 cPs at 25 °C | 15–35 minutes at 25 °C | TDS |
| Filament Winding Grade ResinSPR 301 FW | 200–400 cPs at 25 °C | 20–60+ minutes at 25 °C | TDS |
| Isophthalic Cooling Tower Grade ResinSPR 301 CT | 400–650 cPs | 15–35 minutes at 25 °C | TDS |
| Low-Viscosity Isophthalic ResinSPR 301 LV | 80–180 cPs at 25 °C | 40–90+ minutes at 25 °C | TDS |
| Rock Bolt Grade ResinSPR 301 RB | 2,000–3,500 cPs | See data sheet | TDS |
| Isophthalic SMC ResinSPR 301 SMC | 800–1,400 cPs at 25 °C | 12–18 minutes at 25 °C | TDS |
| Isophthalic DMC ResinSPR 301 DMC | 800–1,400 cPs at 25 °C | 12–18 minutes at 25 °C | TDS |
| ISO Fire Retardant ResinSPR 301 FR | 400 cPs | 5.5 minutes | TDS |
| ISO GelcoatSPR 301 GC | 40,000 cPs at 25 °C | 8 minutes at 25 °C | TDS |
| Tooling Grade ResinSPR 401 TL | 400–650 cPs | 15–30 minutes at 25 °C | TDS |
Choosing a grade
How to choose within isophthalic polyester resins
Linings and storage
Oil-storage tanks and chemical equipment: SPR 301 OT. Organic-solvent storage, sewage and effluent service: SPR 301 OS. The general grade, SPR 301, covers water immersion and chemical-service laminates.
Process-matched grades
Filament winding: SPR 301 FW. Thixotropic lay-up for cooling towers and wind-energy parts: SPR 301 CT. Jute reinforcement: SPR 301 LV. Rock-bolt anchoring compounds: SPR 301 RB (the base resin, not a capsule).
Surfaces and moulds
Mould-face surfaces facing weathering or water: SPR 301 GC. Composite moulds and tooling: SPR 401 TL, the isophthalic NPG tooling resin.
Isophthalic chemistry improves resistance relative to orthophthalic grades; it is not a compatibility guarantee for a particular chemical. The medium, its concentration and temperature, and the laminate construction decide suitability — share them for a service-specific review. For more aggressive corrosion service, compare the vinyl ester SPR 501 family.
Process guides
Application guides
Guides
Read before you specify
What Is ISO Resin? Isophthalic Polyester Resin ExplainedISO Polyester Resin is an isophthalic unsaturated polyester resin. Understand what the isophthalic backbone actually changes, why it resists water and chemicals better than a general-purpose grade, where it is specified, and what ISO does and does not mean in this product name.ISO Polyester Resin vs GP Resin: When Is the Step Up Worth It?Isophthalic and orthophthalic resins look and handle almost identically in the workshop. Understand what actually changes in the backbone, where the difference shows up in service, and the cases where paying for isophthalic is simply wasted.How to Specify and Buy ISO Polyester ResinA practical procurement guide for isophthalic polyester resin: the service data that actually determines the grade, the construction decisions that matter more than resin choice, the documents worth requesting, and the questions that avoid a mis-specified vessel.ISO Polyester Resin Applications: Where Isophthalic Grades Are UsedWhere isophthalic polyester resin is genuinely specified: chemical tanks and bunds, process pipework and ducting, marine skin coats, water and effluent equipment, sanitaryware, pultrusion and filament winding, and how the laminate is built in each case.ISO Polyester Resin vs Vinyl Ester: Where the Line FallsVinyl ester is the usual step up from isophthalic polyester for aggressive service. Understand the structural reason vinyl ester resists chemicals and heat better, what it costs in money and process discipline, and how to judge which side of the line your duty sits on.What Is ISO Gelcoat? Isophthalic Gelcoat ExplainedA gelcoat is not pigmented resin. Understand what an isophthalic gelcoat actually is, why air inhibition is deliberate, where ISO sits between orthophthalic and ISO-NPG, and what it can and cannot protect against.
Other resin chemistries
Browse by resin chemistry
SPR 201 · Orthophthalic Polyester ResinsSPR 201 orthophthalic (ortho) unsaturated polyester resins made at Doraha, Punjab: general-purpose, casting, sheet, SMC/DMC, fire-retardant and gelcoat grades.SPR 401 · Terephthalic Polyester ResinsSPR 401 terephthalic polyester resins from Doraha, Punjab: SMC and DMC moulding-compound resins, a fire-retardant gelcoat and a heat-cured pultrusion grade.SPR 501 · Vinyl Ester ResinsVinyl ester resin family (SPR 501): when corrosion-resistant FRP linings and chemical-service structures call for vinyl ester instead of isophthalic polyester.FRP resin by jobStart from the part you make and find the matching grade and data sheet.Resin selectorAnswer a few questions about the process and part to shortlist grades.
Ordering isophthalic resin: questions buyers ask
Choose the grade, send the quantity and delivery location, and we reply with a quotation. Call +91 74638 81652, message us on WhatsApp +91 74638 81005 or email info@samratpolyresins.in.
An unsaturated polyester resin built on isophthalic acid. It is specified where a laminate faces water immersion, chemical service or sustained outdoor conditions. Here ISO names the chemistry, not a certificate.
GP (orthophthalic) resin is the usual choice for hand lay-up, spray-up, sheets and everyday mouldings with no water, chemical or fire demand. Choose isophthalic where the laminate faces water immersion, chemical service or sustained outdoor conditions. Corrosion resistance still depends on the medium, its concentration and temperature, and the laminate construction, so confirm the grade on a trial of the real part.
12 published grades: ISO Polyester Resin, Oil Storage Tank Grade Resin, Organic Solvent-Resistant Grade Resin, Filament Winding Grade Resin, Isophthalic Cooling Tower Grade Resin, Low-Viscosity Isophthalic Resin, Rock Bolt Grade Resin, Isophthalic SMC Resin, Isophthalic DMC Resin, ISO Fire Retardant Resin, ISO Gelcoat and Tooling Grade Resin. Each is manufactured at Doraha, Ludhiana, Punjab.
ISO Polyester Resin: 225 kg industrial drum; ISO Fire Retardant Resin: 35 kg / 225 kg. For Oil Storage Tank Grade Resin, Organic Solvent-Resistant Grade Resin, Filament Winding Grade Resin, Isophthalic Cooling Tower Grade Resin, Low-Viscosity Isophthalic Resin, Rock Bolt Grade Resin, Isophthalic SMC Resin, Isophthalic DMC Resin, ISO Gelcoat and Tooling Grade Resin, packaging is confirmed with the quotation.
Prices are quoted on request, for your grade, monthly quantity and delivery location. Send those details on WhatsApp (+91 74638 81005), call +91 74638 81652 or email info@samratpolyresins.in. How ordering works.
Yes. ISO Polyester Resin, Oil Storage Tank Grade Resin, Organic Solvent-Resistant Grade Resin, Filament Winding Grade Resin, Isophthalic Cooling Tower Grade Resin, Low-Viscosity Isophthalic Resin, Rock Bolt Grade Resin, Isophthalic SMC Resin, Isophthalic DMC Resin, ISO Fire Retardant Resin, ISO Gelcoat and Tooling Grade Resin each link a technical data sheet (PDF) with the published specification.
Yes. Supply covers Punjab, Haryana, Delhi, Uttar Pradesh, West Bengal, Bihar, Jharkhand, Odisha, Assam and Andhra Pradesh, with exports to Nepal, Bangladesh, Ethiopia, Cameroon and South Africa.
Traders and distributors can send a dealer enquiry with their firm, location and expected monthly volume on the dealer and distributor enquiries page.
Enquiry
Discuss a isophthalic resin requirement
Tell us the process, the finished part, the service condition and the quantity, and the technical team can suggest a starting grade to trial. Samrat Poly Resins manufactures at Doraha, Punjab. Pricing is on request.