Polythiol monomers are versatile building blocks for UV-curable coatings, adhesives, optical resins, and epoxy curing systems. The SINOMER® series offers three distinct polythiol products – BMPT, TMPMP, and PETMP – each designed for specific performance requirements.
The fundamental advantage of thiol-based chemistry lies in the thiol-ene click reaction, which delivers:
Low curing shrinkage – significantly lower than conventional acrylate systems
Reduced oxygen inhibition – improves surface cure without nitrogen protection
Fast curing speed – even at low temperatures and in thin films
Improved adhesion – to metals, glass, and plastics
CAS: 131538-00-6 | Synonyms: 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol; THIOCURE DMPT; Polythiol DMPT
BMPT is a trifunctional polythiol specifically engineered for high-end optical applications, particularly 1.67 high refractive index spectacle lenses.
| Parameter | Value |
|---|---|
| Refractive Index (20°C) | 1.6300 – 1.6350 |
| Appearance | Colorless transparent liquid |
| APHA Color | ≤ 8 |
| Water Content | ≤ 500 ppm |
High refractive index – enables ultra-thin, lightweight lenses
High Abbe number – excellent optical clarity with minimal chromatic aberration
High definition – superior optical quality for precision progressive lenses
Strong impact resistance – 6× more impact-resistant than conventional lenses
Good dyeing property – easy to tint for prescription and fashion lenses
1.67 high refractive index spectacle lenses
High refractive index optical resin monomers for automotive glass and eyeglass lenses
BMPT is also used in polythiourethane optical matrices, combined with isocyanate monomers to produce high-performance lens materials. Its three thiol groups provide high crosslinking density for optical clarity and mechanical strength.
CAS: 33007-83-9 | Chemical Name: Trimethylolpropane tris(3-mercaptopropionate)
TMPMP is a trifunctional thiol widely used as a crosslinking agent in thiol-ene and thiol-acrylate polymer systems.
| Parameter | Value |
|---|---|
| Appearance | Colorless transparent to yellowish liquid |
| Purity | ≥ 95% (industrial grade) |
| Refractive Index | 1.5170 – 1.5180 |
| Density (25°C) | 1.200 – 1.215 g/cm³ |
Trifunctional crosslinking – provides balanced crosslink density for improved mechanical and thermal properties
Versatile reactivity – participates in thiol-ene, thiol-epoxy, and thiol-isocyanate reactions
Enhanced adhesion, hardness, and toughness – improves coating performance
Good compatibility – with acrylic, epoxy, and polyurethane systems
UV/EB curing coatings – light curing coatings, photosensitive materials
Printed circuit boards – as a crosslinking and functional additive
Adhesives and sealants – improves adhesion and mechanical properties
Optical materials – improves transparency and refractive index of resins
Hydrogels – via crosslinking inulin derivatives
In UV curing systems, TMPMP enhances surface cure by reducing oxygen inhibition, providing faster and more complete curing in air.
CAS: 7575-23-7 | Chemical Name: Pentaerythritol tetrakis(3-mercaptopropionate)
PETMP is a tetrafunctional thiol with four –SH groups per molecule, delivering the highest crosslink density among the three products. It is widely used in UV/LED curing, epoxy systems, and high-performance adhesives.
| Parameter | Value |
|---|---|
| Appearance | Colorless transparent liquid |
| Sulfhydryl Content | 25 – 27% |
| Refractive Index | ≥ 1.529 |
| APHA Color | ≤ 15 |
| Density (25°C) | 1.28 g/mL |
Tetrafunctional crosslinking – four –SH sites create dense, stable 3D networks
Rapid curing – fast polymerization under UV/LED, even in low-light areas
Low shrinkage & stress – reduces warping, cracking, and interfacial debonding
Oxygen inhibition resistance – eliminates tacky surfaces without nitrogen protection
Good compatibility – with acrylic, epoxy, polyurethane, and silicone systems
UV coatings, inks & adhesives – improves surface cure, reduces shrinkage, enhances adhesion and flexibility
Epoxy resin curing – as a low-temperature curing agent and crosslinker
Optical lens monomers – used in polythiourethane optical matrix synthesis
Rubber vulcanization – accelerates curing and enhances crosslinking
Metal surface treatment – improves coating adhesion and protection
Structural adhesives – provides weather resistance and anti-aging properties
PETMP can be directly added to existing UV formulations without requiring complete system redesign, making it an efficient upgrade for performance improvement.
| Feature | BMPT | TMPMP | PETMP |
|---|---|---|---|
| CAS No. | 131538-00-6 | 33007-83-9 | 7575-23-7 |
| Functionality | Trifunctional | Trifunctional | Tetrafunctional |
| Refractive Index | 1.6300 – 1.6350 | 1.5170 – 1.5180 | ≥ 1.529 |
| Primary Application | High-index optical lenses | UV coatings, PCBs, adhesives | UV/LED systems, epoxy curing |
| Key Advantage | Highest refractive index | Versatile crosslinker | Highest crosslinking density |
| Low Shrinkage | ✓ | ✓ | ✓ |
| Low Color | ✓ (≤ 8 APHA) | ✓ | ✓ (≤ 15 APHA) |
| Oxygen Inhibition | Low | Low | Lowest |
| Compatibility | Optical resins, epoxy | Acrylic, epoxy, polyurethane | Acrylic, epoxy, PU, silicone |
| If you need... | Choose |
|---|---|
| 1.67 high refractive index optical lenses | BMPT |
| UV coatings with balanced crosslinking | TMPMP |
| Maximum crosslinking density & cure speed | PETMP |
| Low shrinkage & dimensional stability | PETMP or TMPMP |
| Best adhesion to metals and glass | PETMP |
| Optical clarity with high Abbe number | BMPT |
| Direct drop-in for existing UV formulations | PETMP |
All three products participate in the thiol-ene click reaction, offering:
Delayed gel point – better process control
High conversion – efficient material utilization
Low shrinkage and stress – improved dimensional stability
Oxygen tolerance – surface cure without nitrogen protection
Fast curing – even in thin films and at low temperatures
Packaging : 25 kg, 30 kg, or 250 kg / drum
Storage: Keep in dry, clean, well-ventilated warehouse. Avoid light and heat. Protect from leakage, rain, and direct sunlight during transportation.
A: BMPT is a trifunctional thiol with the highest refractive index (1.63), specifically designed for optical lenses. TMPMP is a trifunctional thiol for UV coatings and crosslinking. PETMP is a tetrafunctional thiol with four –SH groups, providing the highest crosslink density and fastest cure speed.
A: BMPT offers the highest refractive index (1.6300–1.6350) and is specifically designed for 1.67 high-index spectacle lenses.
A: Yes. All three products are UV-reactive and participate in thiol-ene photopolymerization. PETMP is particularly effective in UV/LED curing with excellent oxygen inhibition resistance.
A: Thiol-ene systems offer low shrinkage, low stress, oxygen tolerance, fast curing, and high conversion – significantly outperforming conventional acrylate systems in terms of dimensional stability and surface cure.
A: Yes. All three products can cure epoxy resins at low temperatures, especially when combined with tertiary amine accelerators. PETMP is particularly effective as a low-temperature epoxy curing agent.
A: Under proper storage conditions (original sealed packaging, cool, dry, away from light), shelf life is typically 12–24 months.
A: PETMP provides the best adhesion to metal, glass, and various plastic substrates due to its four thiol groups and high crosslink density.
A: Yes. PETMP can be directly added to existing UV adhesives, coatings, or ink formulations without requiring complete system redesign. TMPMP and BMPT are also compatible with most acrylic, epoxy, and polyurethane systems.
Sinocure Chemical Group
No. 61, South Industrial Road, Jinan Area of Shandong Pilot Free Trade Zone, China
Email: Info@sinocurechem.com | Tel: +86 15668330235
Website: www.sinocurechem.com
For free samples, technical data sheets, or custom formulation support, please contact our technical team.
This document is for informational purposes only. Users should conduct their own testing to determine suitability for their specific applications. SINOMER® is a registered trademark of Sinocure Chemical Group.
