Thixotropic Hand Lay-up UPR

Thixotropic Hand Lay-up UPR is an orthophthalic unsaturated polyester resin that has been pre-thickened with fumed silica or organoclay thixotropes to produce a gel-like, paste consistency that resists drainage and sagging on vertical and inclined surfaces. This is the workhorse resin for manual hand lay-up of large structures such as boat hulls, tanks, and architectural panels.

The thixotropic index (TI) of 3-6 ensures the resin flows easily under brush or roller action (shear thinning) but quickly recovers its gel structure when shear is removed, preventing styrene draining and resin sag. This property is critical for achieving uniform resin content in vertical laminates and reducing styrene evaporation by maintaining the resin in place on the fiber surface.

Viscosity under high shear (Brookfield spindle at 20 rpm) is 500-800 mPa·s, rising to 2,000-4,000 mPa·s at rest. Gel time at 25°C with 1.5% MEKP is 15-25 minutes. Cured flexural strength is 100-120 MPa. Suitable for hand lay-up of boat hulls, tanks, vessel covers, and any large-surface FRP structure where vertical or overhead lamination is required.