Application guide

Resin for Jute-Reinforced Composite Mouldings

Where the low-viscosity isophthalic grade designed for jute reinforcement fits in jute composite moulding, and what the moulder has to trial.

A thin resin designed for impregnating jute.

Jute-reinforced composites use jute fibre as the reinforcement in a polyester matrix, and the first job of the resin is to impregnate the jute thoroughly. Low-Viscosity Grade Resin (SPR 301 LV) is the grade the catalogue describes as a low-viscosity isophthalic resin designed for jute reinforcement; What Is Low-Viscosity Grade Resin? explains the grade. This guide covers where it fits in jute moulding and what the moulder still has to establish.

What manufacturers build

Jute-composite moulders impregnate jute mat or fabric with resin and mould it into panels, boards and shaped parts. The catalogue lists the impregnation of jute reinforcement and jute-reinforced composite mouldings as the uses of SPR 301 LV. What a finished part is — its thickness, fibre content and intended service — is decided by the moulder and proved on its own parts.

Why this material suits the work

The catalogue lists SPR 301 LV as a clear, water-white to light-straw liquid of 80–180 cPs at 25 °C, with a gel time of 40–90+ minutes at 25 °C, a specific gravity of 1.03–1.09 and 42–50% styrene by weight, supplied non-accelerated and non-thixotropic. The low viscosity is what the grade is designed around: a thin resin for impregnating jute, with a long gel-time range to work in. It belongs to the isophthalic polyester family. How it differs from a general-purpose clear resin is set out in GP Clear vs low-viscosity isophthalic resin. The values describe the liquid resin, not a moulded part.

Required resin characteristics

Low viscosity for impregnating jute (typical 80–180 cPs at 25 °C)
Non-thixotropic flow, so the resin runs into the fibre rather than sitting on it
A long working window for impregnation and moulding (typical gel time 40–90+ minutes at 25 °C)
Non-accelerated supply, so the moulder sets the cure for its own conditions
Trials on the moulder’s own jute reinforcement and moulding method before production

Process context

In general practice, jute mat or fabric is impregnated with catalysed resin — by brushing, rolling or dipping, depending on the moulder — then placed in or pressed against a mould, left to cure, demoulded and trimmed. The catalogue reference cure for SPR 301 LV is MEKP 1.5% with cobalt octoate 0.2%, each added separately to the resin; a concentrated peroxide is never mixed directly with a cobalt accelerator. The impregnation method, resin-to-fibre ratio, any pressing and the cure schedule are the moulder’s decisions, set on its own trials. The grade is designed for jute; use with glass or other reinforcements must be trialled.

Advantages

A grade the catalogue describes as designed for jute reinforcement
A low typical viscosity of 80–180 cPs at 25 °C for impregnation
A long typical gel-time range of 40–90+ minutes at 25 °C
Non-accelerated, non-thixotropic supply leaves cure and application control with the moulder

Common products

Jute-reinforced composite panels
Jute-reinforced boards and sheets
Shaped jute-composite mouldings

Common questions

Can I use SPR 301 LV with glass mat?

The catalogue describes the grade as designed for jute reinforcement. Use with glass or other reinforcements is not published and must be trialled on your own process.

How strong will a jute part made with it be?

No finished-part figures are published. Strength depends on the jute, the fibre content, the moulding method and the cure, and is established by testing your own parts.

Why is the cobalt in the reference cure 0.2%?

MEKP 1.5% with cobalt octoate 0.2% is the reference cure the catalogue gives for this grade, each added separately. Final dosage is set on your own trials for your workshop conditions.

How is it different from GP Clear Resin?

GP Clear Resin is a general-purpose orthophthalic resin; SPR 301 LV is a low-viscosity isophthalic grade designed for jute. The comparison guide on the two sets out which job each is chosen for.

Moulding with jute?

Tell us the jute reinforcement you use, the parts you mould and the quantity you expect to take. Nepal price, packaging and lead time are confirmed on enquiry.

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