Abstract
SINOMER® PETMP (Pentaerythritol Tetrakis(3-mercaptopropionate)) is a tetrafunctional thiol compound widely used as a curing agent in acrylic resin systems. Its unique thiol-ene click reaction mechanism enables rapid curing, low shrinkage, and high transparency, making it ideal for applications in optical adhesives, electronic encapsulants, and 3D printing resins. This article explores its curing mechanisms, performance advantages, and compatibility with other resin systems, including epoxy.
1. Introduction
SINOMER® PETMP is a high-performance thiol-based curing agent designed for advanced polymer systems. With four reactive mercapto (-SH) groups, it facilitates efficient crosslinking in acrylic resins via thiol-ene chemistry, while also exhibiting potential in epoxy and hybrid resin formulations.
2. Curing Mechanisms
2.1 Thiol-Ene Click Reaction
SINOMER® PETMP reacts with double bonds in acrylic resins (e.g., acrylates or methacrylates) through a radical-mediated thiol-ene click reaction, characterized by:
- High Speed: Curing completes within seconds to minutes under UV/thermal initiation.
- Low Shrinkage (<5%): Minimizes internal stress and material deformation.
- High Conversion: Near-stoichiometric reaction between thiols and enes ensures minimal residual monomers.
2.2 Radical Chain Transfer
As a chain transfer agent, SINOMER® PETMP regulates molecular weight distribution in free-radical polymerization systems when combined with traditional initiators (e.g., peroxides or photoinitiators).
3. Application Systems and Conditions
3.1 Acrylic Resin Systems
- UV-Curable Systems:
- Formula Example:
- Acrylate resin: 80–90%
- SINOMER® PETMP: 5–15%
- Photoinitiator (e.g., TPO): 1–3%
- Advantages: Ideal for optical films, coatings, and thick-section curing (e.g., lenses, adhesives).
- Formula Example:
- Thermal-Curable Systems:
- Initiation: Thermal initiators (e.g., AIBN) at 60–100°C.
- Applications: High-temperature-resistant adhesives, potting materials.
3.2 Epoxy Resin Systems (Potential Applications)
While primarily optimized for acrylics, SINOMER® PETMP shows promise in epoxy-thiol hybrid systems:
- Mechanism: Thiol-epoxy reactions, offering:
- Reduced Brittleness: Enhanced flexibility compared to traditional amine-cured epoxies.
- Faster Cure: Accelerated kinetics at moderate temperatures.
- Recommended Use: Flexible coatings, composite matrices.
- ★In the two-component epoxy curing system, we recommend another polythiol product as a low-temperature fast epoxy curing agent- SINOMER PM839,This product can full replace Capcure 3-800;GABEPRO GPM-800;Polythiol QE-340M;Thiocure 1200.SINOMER®PM839 is a transparent liquid polymer curing agent with thiol (-SH) termination. Excellent properties when combined with amines or polyamines to cure epoxy resins. Provides fast cure rates at low temperatures and in thin films.For more details of our polythiol products , please click: The first choice epoxy resin curing agent for low temperature and rapid curing/polymercaptan/
4. Performance and Considerations
4.1 Advantages
- Optical Clarity: Cured products are colorless, suitable for optical applications.
- Versatility: Compatible with UV/thermal initiation and multiple resin systems.
- Low Volatile Organic Compounds (VOCs): Environmentally friendly compared to solvent-based systems.
4.2 Challenges and Solutions
- Odor Control: Mild sulfur odor can be mitigated with masking agents or low-odor thiol alternatives.
- Storage Stability: Store in dark, sealed containers with antioxidants (e.g., BHT) to prevent oxidation.
- Compatibility Testing: Pre-testing is advised for hybrid systems (e.g., epoxy-thiol).
5. Comparison with Traditional Curing Systems
| Property | SINOMER® PETMP Thiol-Ene System | Conventional Free-Radical System |
|---|---|---|
| Curing Speed | Seconds to minutes | Minutes to hours |
| Shrinkage | <5% | 5–15% |
| Transparency | Excellent | Good (may yellow over time) |
| Applications | Optics, electronics, 3D printing | General-purpose coatings, adhesives |
6. Recommended Applications
- Optical Adhesives: Screen lamination, lens encapsulation.
- Electronic Encapsulants: Low-stress potting for circuits.
- 3D Printing Resins: High-resolution, rapid-curing formulations.
- Hybrid Epoxy Systems: Flexible coatings, composite materials.
7. Conclusion
SINOMER® PETMP is a versatile curing agent for acrylic resins, offering rapid curing, low shrinkage, and exceptional optical properties. Its compatibility with UV/thermal initiation and potential in epoxy-thiol hybrid systems broadens its utility across industries. For tailored formulations or technical support, contact Sinocure Chemical Group’s R&D team.
Keywords: Thiol-ene click chemistry, SINOMER® PETMP, acrylic resins, epoxy-thiol hybrids, low-shrinkage curing.
Sinocure Chemical Group
Innovating Polymer Solutions for a Sustainable Future
No. 61, South Industrial Road, Jinan Area of Shandong Pilot Free Trade Zone, China
Tel: +86 15668330235 | Email: info@sinocurechem.com
Note: This document is for technical reference only. Performance may vary based on specific formulations. Always conduct pre-application testing.