STP ShaliProtek 2AC PU TC 50
A two-component aliphatic acrylic polyurethane topcoat that stays glossy and colour-stable under years of UV, with high solar reflectance to keep facades and roofs cooler.
What is it?
A 2K, isocyanate-cured aliphatic acrylic polyurethane top coat that is UV-resistant, non-yellowing and high solar-reflective, mixed at 9:1 (v/v).
Where is it used?
Exposed building facades, cool-roof surfaces, and structural steel in coastal, industrial and chemical environments where sunlight and weathering degrade ordinary coatings.
Why use it?
Aliphatic PU chemistry holds gloss and colour under UV (colour change under 2 ΔE after 1000 hrs weathering), reflects solar heat, and resists impact, abrasion and mild chemicals.
How is it applied?
Prime the substrate (ShaliPrime PUM on concrete, ShaliPrime 2E on steel), blend Component B into A, wait ~5 minutes, then brush, roller or spray to a minimum recommended DFT of 50 micron.
About STP ShaliProtek 2AC PU TC 50
STP’s ShaliProtek 2AC PU TC 50 is the aliphatic polyurethane finish coat you reach for when a surface has to look good and stay protected in full sun. It is a two-component, liquid, aliphatic acrylic polyurethane that cures through an isocyanate reaction to give a tough, flexible, glossy film. Because the resin backbone is aliphatic rather than aromatic, the coating does not chalk or yellow the way cheaper PU and epoxy topcoats do once ultraviolet light gets to work on them. That single property is why it is specified as the exposed, weather-facing layer over epoxy anti-corrosive systems, waterproofing membranes and blasted steel across coastal plants, refineries and industrial roofs.
The “50” variant is positioned for solar-reflective, cool-surface duty. On top of the standard aliphatic PU protection, it is formulated to reflect a high proportion of incident solar radiation, so a treated roof deck or facade runs cooler than an untreated dark surface and eases the cooling load on the building. It ships as any-colour pigmented material (a transparent grade also exists in the range) in 4 L and 20 L unit packs, blended at a factory pre-weighed Component A to Component B ratio of 9:1 by volume. For engineers and applicators in Delhi NCR and across India, it slots neatly into a specification as the final, UV-durable, heat-reflective coat over a proven primer and intermediate build.
The technical insight
The durability comes from the resin chemistry. Aromatic isocyanates absorb UV and break down at the molecular level, which is what causes ordinary polyurethanes to chalk, fade and lose gloss outdoors. ShaliProtek 2AC PU TC 50 uses an aliphatic acrylic polyurethane, whose bonds are far more UV-stable, so the cured film keeps its gloss (over 80 at 60 degrees) and holds colour change to under 2 ΔE even after a minimum 1000 hours of accelerated weathering, with gloss loss staying below 25 percent. Curing itself is a two-part isocyanate reaction: Component B (the hardener) cross-links Component A into a dense, continuous film with roughly 57 percent volume solids, which is what delivers the solvent and mild-chemical resistance, 150 kg-inch impact resistance and low abrasion loss. The solar-reflective pigmentation reflects a large share of the sun’s radiant heat instead of letting the substrate absorb it, so surface temperatures and downstream cooling loads drop. The elastic, flexible film also tolerates the daily thermal movement of a hot facade without cracking, which is exactly where a hard, brittle finish would fail.
Where it is used
- UV-durable finish coat over epoxy anti-corrosive systems on structural and plant steel
- Solar-reflective cool-roof coating on concrete and metal deck roofs to cut surface temperature
- Protective topcoat over waterproofing membranes exposed to sunlight and weather
- Coating for offshore structures and marine environments in coastal India
- External protection for petrochemical, pharmaceutical and chemical plant assets
- Colour-stable finish on cement and steel plant structures and equipment
- Exterior coating for rail coaches and chemical wagons subject to abrasion and weather
- Directly applied protective finish on blast-cleaned metal facades
Key advantages
- Aliphatic PU chemistry resists UV and weathering without chalking or yellowing
- High solar reflectance lowers surface temperature and eases building cooling loads
- Holds colour (under 2 ΔE) and gloss (over 80) after 1000+ hours of weathering
- Tough yet flexible film handles thermal movement plus impact and abrasion
- Resists industrial corrosive environments, solvents and mild chemicals
- Can be applied directly to blast-cleaned metal for straightforward steel protection
- Factory pre-weighed 9:1 packs remove site guesswork on mixing
- Applies by brush, roller or spray to suit access and geometry
Limitations & considerations
- It is a topcoat, not a standalone system; it needs a compatible primer (ShaliPrime PUM on concrete, ShaliPrime 2E on steel) and, on steel, an anti-corrosive build beneath
- Contains isocyanate and is flammable, so it demands PPE, ventilation and control of ignition sources during application
- Low temperature, high humidity, rain or water ponding during and after application can cause incomplete curing and blistering
- Apply only within 10 to 40 degrees C ambient and substrate, with substrate moisture below 2 percent
- Multiple coats are usually needed to build meaningful dry film thickness
- As a two-part material it has a limited pot life (roughly 4 to 5 hours per 100 g of mix), so mix only what can be used in time
Selection & best practice
Start with the substrate. Concrete must be cured for at least 28 days, mechanically ground and cleaned of dust, laitance, oil and old paint; steel should be blast-cleaned to Sa 2 to Sa 2.5 depending on severity. Confirm substrate moisture is below 2 percent and that both substrate and air sit between 10 and 40 degrees C. Prime concrete with ShaliPrime PUM and steel (optionally) with ShaliPrime 2E, then let the primer reach touch-dry, typically 6 to 8 hours. Stir Component A thoroughly with a spiral-blade drill mixer at 300 to 400 rpm, add the full factory pre-weighed Component B at the 9:1 volume ratio, mix to a uniform blend and let it stand about 5 minutes so entrapped air escapes. Apply by brush, roller or spray to a minimum recommended DFT of 50 micron, planning for more than one coat where a higher build is specified. Avoid application when rain, high humidity or ponding is likely during cure. Clean all tools immediately with STP Thinner before the material hardens.
Specifications
| Chemistry | Two-component isocyanate-cured aliphatic acrylic polyurethane |
| Mixing ratio | Component A : Component B = 9 : 1 (v/v), factory pre-weighed |
| Theoretical coverage | 9 – 11 m2/L per coat (varies with surface roughness, porosity, method) |
| Recommended DFT | 50 micron minimum per coat |
| Volume solids | 57 +/- 2 % |
| Pot life | 4 – 5 hours per 100 g of mix @ 27 C, 55% RH |
| Drying (touch dry / recoat / hard dry / full cure) | 1 – 2 hrs / 9 – 36 hrs / 80 – 90 hrs / 50 – 60 days |
| Weathering (min 1000 hrs, ASTM D4587/D2244) | Gloss loss < 25%; colour change < 2 dE |
| Pack sizes | 4 L and 20 L unit packs |
Industry use cases
Oil, Gas & Petrochemical
UV-durable finish coat over epoxy anti-corrosive systems on plant steel and offshore structures in aggressive coastal atmospheres.
Commercial & Industrial Roofing
High solar-reflective cool-roof coating on concrete and metal decks to cut surface temperature and trim air-conditioning loads.
Chemical & Pharmaceutical Plants
Colour-stable, mild-chemical-resistant topcoat that protects external structures and equipment in corrosive process environments.
Infrastructure & Rolling Stock
Abrasion- and weather-resistant finish for rail coach and chemical wagon exteriors that must hold appearance in service.
Cement & Steel Plants
Tough aliphatic PU finish applied directly over blast-cleaned steel to protect exposed structural assets from UV and industrial fallout.
Frequently asked questions
Is ShaliProtek 2AC PU TC 50 a complete coating system on its own?
How much area does one litre cover?
What makes it different from a normal PU or epoxy topcoat?
What is the mixing ratio and pot life?
In what conditions should it not be applied?
What pack sizes does Space Arc supply and where?
How we position STP ShaliProtek 2AC PU TC 50
Within the STP ShaliProtek family, pair TC 50 with the right primer for the substrate: ShaliPrime PUM under it on concrete and ShaliPrime 2E on steel, over an epoxy anti-corrosive intermediate where corrosion protection is the priority. The transparent grade of ShaliProtek 2AC PU TC suits situations where you want UV protection without hiding the substrate. For the roofing and facade side of a project, Space Arc can also supply STP’s ShaliCem and membrane waterproofing systems that this coat is designed to protect. Across our other brands, teams needing a breathable, water-based anti-carbonation facade finish (rather than a solvent-based 2K PU) often look at Fosroc’s Dekguard range as an alternative approach.
Fosroc Dekguard Elastic — A specifier who wants a single-component, water-based, crack-bridging anti-carbonation facade coating that is easier to apply and lower-VOC may prefer Dekguard Elastic, accepting acrylic durability instead of the harder, chemical-resistant 2K aliphatic PU film of ShaliProtek.
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