Shin-Etsu Silicones of America, Inc. has launched a new line of long-chain spacer type silane coupling agents that offer increased hydrophobicity and flexibility.

New to the coatings, adhesives and sealants industries, the KBM-1083 (olefinic functional) and KBM-4803 (epoxy functional) lines have eight carbons – creating more space between the reactive ends of the silanes. Typical silane coupling agents have three carbons separating the organic functional group from the inorganic silicon end. These traditional 3-carbon spacer silanes create a tighter, more rigid network than their 8-carbon counterparts.

The result of this ‘greater space’ presents a significant myriad of benefits that can be formulated into a wide variety of chemistries for coatings, adhesives, sealants and PSA applications including:

• Increased reactivity due to easier access to the reactive group;
• Improved adhesion;
• Enhanced flexibility of the cured resin;
• Higher filler content enabled;
• Greater alkali resistance;
• More compatibility with plastics.

 

KBM-1083 Profile: (Olefinic Functional)

General Properties (not specified values)

• Purity (GC%): 90 or higher 
• Viscosity (25 °C): 1.8cSt

Expected Effects:

• Enables higher filler contents
•  Increased flexibility of cured resin
• Increased alkali resistance and water resistance

 

KBM-4803 Profile: (Epoxy Functional)

General Properties (not specified values)

• Purity (GC%): 95 or higher
• Viscosity (25 °C): 6.6cSt

Expected Effects:

• Increased adhesion
• Increased flexibility of cured resin
• Increased alkali resistance and water resistance
• Enables higher filler contents

 

Tack-Free Comparison: The use of KBM-1083 resulted in a tack-free time that was one-fifth of that using a typical silane coupling agent–KBM-1003, and the Alkali resistance was improved.

 

 

 

Glass-Epoxy Coupling Performance: KBM-4803 accounted for an 18% improvement in interfacial shear strength compared to KBM-403. The product is not water-soluble and has been successfully used in dental, electronics, and aerospace applications.

 

 

Cured Resin Film Test: Due to its longer molecular chain, the KBM-4803 shrank less than the KBM-403 in the cured film test resulting in no observed warpage.

 

 

Silica Treatment: Fumed silica was treated with both KBM-4803 and KBM-403 and compounded with multi-functional epoxy at 10% loading. The viscosity of the compound with KBM-4803 was less than half of that with the traditional silane. The benefit is faster blending with less energy required.

 

 

Cationic Polymerization Activity: KBM-4803 exhibits higher polymerization activity compared to KBM-403 as evidenced by the higher heat value and the shorter peak time.

 

 

According to SESA’s International Business Development Manager for Silanes Technology, Michael Gunther, Ph.D., “Ultimately, this new line of long-chain spacer type 8-carbon silane coupling agents represents a great addition to SESA’s growing silane product portfolio in North America. We are confident that their increased hydrophobicity and flexibility will provide formulators infinite product options and advantages across a vast array of applications in the coatings, adhesives and sealants market segments.”

For more detailed information, visit the Shin-Etsu Silicones web site at www.shinetsusilicones.com.

By Shin-Etsu Silicones of America, Inc.