In modern industrial bonding, electronics encapsulation, and automotive composite repairs, formulation engineers constantly face the challenge of balancing open assembly time (pot life) with rapid demolding and cure throughput. While standard amine and polyamide curing agents require hours or elevated temperatures to achieve structural strength, Polymercaptan (Polythiol) curing agents offer unparalleled fast-curing kinetics at ambient and sub-zero temperatures (down to -20°C).
To eliminate the guesswork in formulation design, SINOCURE Chemical Group has systematically structured its SINOMER® Polymercaptan Portfolio into four distinct, application-driven tiers: Base Unaccelerated Resin, Ultra-Fast Seconds Series, Standard Fast-Curing Minutes Series, and Extended Working Life Series.
The SINOMER® polythiol family is categorized by reaction kinetics and operational windows, allowing formulators to select the exact speed required for automated or manual dispensing:
1. Base mercaptan (Unaccelerated)
• SINOMER® PM839: Pure unaccelerated polythiol (Full formulation flexibility for custom catalysts)
2. Ultra-Fast Series (Seconds / Instant Fixing)
• SINOMER® PM839-S40: ~40 Seconds Gel Time (Emergency field repair & spot fixing)
• SINOMER® PM839-S90: ~90 Seconds Gel Time (Automated precision assembly)
3. Standard Fast-Curing Series (5 to 20 Minutes / High-Volume Production)
• SINOMER® PM840-M5: ~5 Minutes Gel Time (General 5-minute structural epoxy)
• SINOMER® PM840-M10: ~10 Minutes Gel Time (Electronic component potting & sealing)
• SINOMER® PM840-M15: ~15 Minutes Gel Time (Multi-point manual assembly)
• SINOMER® PM840-M20: ~20 Minutes Gel Time (Complex joint alignment & injection)
4. Extended Working Life Series (30+ Minutes / Large-Part Potting)
• SINOMER® PM841-M30: ~30 Minutes Gel Time (Large-volume potting & wide-area bonding)
Formulator's Selection Rule:
"While the PM840 Series focuses on standard fast-curing assembly (5–20 minutes), the PM841 Series is engineered specifically for extended open time and large-volume potting (30 minutes and above). This clear distinction allows engineers to precisely balance pot life with rapid demolding efficiency."
Function: Pure, unpromoted polymercaptan resin.
Why Choose It: Designed for advanced R&D formulators who require complete control over gel time, exotherm, and pot life by adjusting their own tertiary amine catalysts (such as DMP-30 or Sinepoxy® AA-160) or using it as a flexible co-curing modifier for standard amine/polyamide systems.
Key Equivalence: Equivalent in performance to international benchmarks such as Capcure® 3-800, GABEPRO® GPM-800, Polythiol QE-340M, and Thiocure® 1200.
SINOMER® PM839-S40 (40 Seconds): The fastest ambient-temperature curing system in the portfolio. Creates an ultra-rapid green strength bond within a minute, ideal for instant structural fixing, optical lens positioning, and extreme sub-zero field maintenance.
SINOMER® PM839-S90 (90 Seconds): Provides a slight extension in working window for fast automated dispensing lines, preventing clogging in high-speed static mixing heads.
SINOMER® PM840-M5 (5 Minutes): The benchmark for 1:1 or 1:2 dual-barrel DIY and industrial 5-minute epoxy adhesives. Delivers high clarity, low odor, and excellent adhesion to metals, ceramics, glass, and composites.
SINOMER® PM840-M10 (10 Minutes) & PM840-M15 (15 Minutes): Balanced grades providing sufficient time for manual workpiece alignment, micro-electronic potting, and crack injection sealing.
SINOMER® PM840-M20 (20 Minutes): Engineered for assemblies requiring intricate part alignment or multi-cavity potting without premature gelation.
SINOMER® PM841-M30 (30 Minutes): Traditional fast mercaptans generate high exotherm when mixed in large batches. PM841-M30 mitigates peak exotherm while ensuring thorough, tack-free deep-section cure within 1–2 hours, making it the ideal choice for large-component potting, architectural anchoring, and structural composite laminations.
| Grade Name | Gel Time (25°C) | Catalyst State | Mixing Ratio (w/ DGEBA) | Primary Applications |
|---|---|---|---|---|
| SINOMER® PM839 | Adjustable (1–60 min) | Unaccelerated | 1:1 + 5–10% Accelerator | Custom formulations, co-curing toughening |
| SINOMER® PM839-S40 | ~40 Seconds | Pre-accelerated | 1:1 (w/w) | Emergency pipe repair, instant tacking |
| SINOMER® PM839-S90 | ~90 Seconds | Pre-accelerated | 1:1 (w/w) | High-speed automated assembly lines |
| SINOMER® PM840-M5 | ~5 Minutes | Pre-accelerated | 1:1 (w/w) | Classic 5-min epoxy adhesives, DIY kits |
| SINOMER® PM840-M10 | ~10 Minutes | Pre-accelerated | 1:1 (w/w) | Electronics potting, LED sealing |
| SINOMER® PM840-M15 | ~15 Minutes | Pre-accelerated | 1:1 (w/w) | Multi-part structural bonding, stone glue |
| SINOMER® PM840-M20 | ~20 Minutes | Pre-accelerated | 1:1 (w/w) | High-precision optical & sensor encapsulation |
| SINOMER® PM841-M30 | ~30 Minutes | Pre-accelerated | 1:1 (w/w) | Large potting units, civil crack injection |
Sub-Zero & Rapid Ambient Curing: Cures rapidly at temperatures ranging from -20°C to +25°C where conventional amine hardeners completely stall.
High Optical Clarity & Non-Blushing: Yields crystal-clear cured films with zero amine blush or surface oiling, perfect for decorative coatings and transparent bonding.
Broad Substrate Adhesion: Exceptional chemical bonding to difficult substrates including glass, polished ceramics, anodized aluminum, carbon fiber, and damp concrete surfaces.
Stable Quality & REACH/RoHS Compliance: Ultra-low volatile residuals, consistent mercaptan equivalent weight, and rigorous batch-to-batch quality control.
Q1: What is the primary difference between PM839 and pre-accelerated grades (PM840 / PM841)?
A: SINOMER® PM839 is an unaccelerated base polythiol containing no tertiary amine promoter. It offers formulators full freedom to tailor reaction speeds and shelf stability. In contrast, the PM839-S, PM840-M, and PM841-M series are pre-formulated with optimized promoters to deliver ready-to-use, standardized gel times (from 40 seconds to 30 minutes) at a simple 1:1 mixing ratio with standard DGEBA liquid epoxy resins.
Q2: Can SINOMER® polythiols be used with standard amine or polyamide hardeners?
A: Yes. SINOMER® PM839 is frequently utilized as a reactive accelerator and flexibilizer in polyamide, cycloaliphatic amine, and polyetheramine formulations, significantly accelerating cure speed while enhancing low-temperature impact resistance.
Looking to optimize your rapid-curing epoxy formulation or replace existing Capcure® / GABEPRO® grades?
Contact SINOCURE Technical Support at info@sinocurechem.com to request technical data sheets (TDS), safety data sheets (SDS), and laboratory testing samples.
