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.

 

TABLE 1 »

 

 

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.

 

FIGURE 1 »

 

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.

 

TABLE 2 »

 

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.

 

TABLE 3 »

 

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.

 

FIGURE 2 »

 

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.