1 Overview

Silane oligomers are a class of silane coupling agents with 3-5 degrees of polymerization, synthesized from specific silane coupling agent bases, supplemented with terminating agents, catalysts, and stabilizers. Compared to conventional silane coupling agents, they offer longer molecular chains, better molecular flexibility, improved system stability, and provide enhanced adhesion, boiling water resistance, chemical resistance, abrasion resistance, heat resistance, weather resistance, and unique flexibility.

Mercapto silane oligomers are oligomeric organosilicon compounds containing reactive mercapto (-SH) and hydrolyzable siloxane structures. Compared to monomeric silanes, they offer more uniform film formation, greater stability, higher functionality, and superior reactivity. Their unique chemical structure enables wide applications in surface treatment, coatings, environmental protection, and solves many pain points of traditional materials.

2 Applications

2.1 Metal Surface Treatment

Primarily used for anti-corrosion passivation and surface modification of metals, replacing traditional phosphating and chromate treatment processes, solving environmental issues such as phosphorus content, heavy metals, and waste sludge generation, while improving metal surface performance. Siloxane groups hydrolyze to form Si-OH, which condenses with metal surface hydroxyl groups (Fe-OH, Al-OH) to form a dense Si-O-M (M = metal ion) chemical bonding film, isolating air, moisture, and other corrosive media. The mercapto group (-SH) forms strong chelates with metal ions such as Cu, Ag, Au, Fe, and Zn, further inhibiting metal oxidation, corrosion, and discoloration, while enhancing subsequent coating or adhesive adhesion.

Qingdao Kunji New Material Technology Co., Ltd. published patent "A High-Durability Metal Corrosion Inhibitor and Its Preparation Method," where γ-mercaptopropyltrimethoxysilane is hydrolyzed and reacted with triethyl phosphite to produce bis(γ-mercaptopropyl)phosphonate-modified polysiloxane. The product achieves long-term corrosion inhibition through chemical adsorption of mercapto and phosphonate groups with metals, chelation via the imidazolidinone ring, and water repellency from the fluorocarbon chain, significantly enhancing metal protection in harsh environments.

Wuxi Yongxing Metal Hose Co., Ltd. published patent "A Preparation Method of Anti-Corrosion Treatment Fluid for Metal Bellows," where mercaptopropyltriethoxysilane is added to the formulation. The resulting anti-corrosion treatment fluid significantly improves the corrosion resistance of treated metal bellows without any adverse effects.

Jiangsu Dafang Metal Powder Co., Ltd. published patent "A Modified Ultrafine Spherical Copper Powder for Photovoltaic Silver-Coated Copper and Its Preparation Method," where mercapto silane pretreatment constructs a 2-5 nm molecular-level bonding layer on the copper powder surface. Using an EDTA-sodium citrate composite complexation system at 40-45°C, a dense 80±5 nm silver layer is deposited. The resulting spherical copper powder reduces slurry rheological shear stress, effectively lowers printed grid line breakage rate, exhibits good oxidation resistance, and meets the core conductivity requirements of HJT cells.

2.2 Coatings

Mercapto silane oligomers are used in coatings as modifiers, crosslinking agents, or adhesion promoters to improve adhesion, weather resistance, abrasion resistance, and corrosion resistance, while enhancing application properties and suitable for waterborne coating systems.

2.2.1 Coating Adhesion Promoter

Acting as a "bridge" between coating and substrate, the siloxane group bonds to the substrate (metal, glass, concrete, etc.), while the mercapto group crosslinks with resin systems (polyurethane, epoxy, acrylic) in the coating, significantly improving adhesion and solving issues such as peeling, detachment, and blistering.

Guangzhou Jointas Chemical Co., Ltd. published patent "A Waterborne Low-Temperature Baking Paint and Its Preparation Method and Application," where waterborne mercapto silane is added. The resulting waterborne low-temperature baking paint rapidly crosslinks and cures at 90-110°C, and the cured film exhibits excellent adhesion to multiple substrates along with superior corrosion and wear resistance.

2.2.2 Coating Modifier

Leveraging the high reactivity of mercapto groups and the weather resistance/water repellency of siloxanes, the oligomer modifies coating resins to improve weather resistance, abrasion resistance, water resistance, and corrosion resistance, while reducing VOC content and enhancing environmental performance.

Keshun Waterproof Technology Co., Ltd. published patent "A Multiple-Curing PMMA Elastic Waterproof Coating Composition and Its Preparation Method," where mercapto silane coupling agent is added. The mercapto group undergoes Michael addition click chemistry with double bonds under free radical initiation, introducing organosiloxane structures onto PMMA side chains for moisture curing. Additionally, the mercapto group acts as a chain transfer agent, effectively controlling PMMA molecular weight during free radical polymerization, reducing large PMMA molecule formation, and improving PMMA conversion rate. Furthermore, the mercapto compound enhances air-drying properties, counteracts oxygen inhibition, and achieves a smooth coating surface.

2.3 Environmental Protection

Leveraging the strong chelation of mercapto groups with heavy metal ions and the curable nature of siloxanes, mercapto silane oligomers offer unique advantages in wastewater treatment, soil remediation, and other environmental fields, with no secondary pollution, aligning with green environmental principles.

When injected into heavy metal-contaminated soil, the mercapto groups chelate with heavy metal ions to form stable, insoluble complexes, immobilizing the heavy metal ions, preventing their migration and diffusion, and reducing contamination of groundwater and crops. Meanwhile, the siloxane groups improve soil permeability and stability, promoting soil microbial activity and accelerating soil remediation.

Tianjin Tianrun Yikang Environmental Technology Co., Ltd. published patent "A Mercapto-Modified Clay for Heavy Metal Adsorption and Its Preparation Method," where mercaptopropyltrimethoxysilane, ethanol, and deionized water are mixed to prepare a mercapto silane solution. The solution is mixed with acidified clay, stirred repeatedly, and the reaction product is collected, dried, and ground to obtain mercapto-modified clay. The resulting product exhibits strong adsorption capacity, fast adsorption rate, no secondary pollution, broad applicability, and a simple, low-cost preparation method suitable for large-scale application.

3 Product Introduction

Wuhan Hugarise New Material Co., Ltd. offers Mercapto Silane Oligomer (PCU-S80) , Substitute of Momentive CoatOSil T-Cure.