Shin Etsu, industry partners debut new silicone processing technology

AKRON—Shin Etsu Silicones of America, along with several industry partners, debuted a pair of "wayfarer-style" sunglasses at the 2022 Silicone Expo in Detroit in October.

And while the Ray-Ban-like sunglasses were a hit, it was Shin Etsu's liquid injection molding system "KEG-2001-60" that caught the watchful eyes of expo-goers.

The new materials maintain "advanced handling and molding properties," according to Shin Etsu.

The LIMS silicone is supplied as two translucent components, mixed in a 1:1 ratio, with a 60 durometer and Shore A hardness with low viscosity.

"The material features high tear strength, rapid cure time at elevated temperature, and long pot life at room temperature," Shin Etsu said.

Outside of the complex geometries required by the wayfarer sunglasses, the silicone is excellent for use in O-rings, diaphragms, gaskets, medical devices, baby care components and consumer products.

Shin Etsu was assisted in the demonstration application process by Sumitomo Demag Plastics Machinery of Suwanee, Ga., using one of Sumitomo's all-electric injection molding machines.

"This is great for micro-molded LSR parts where a fraction of a millimeter means the difference between a good and bad part—particularly with optical grade parts that require precision to maintain their optical integrity," said Tony Marchelletta, Sumitomo's national sales manager.

The demonstration also was assisted by Nexus Elastomer Systems Inc., in Chicago, which featured its Servomix X200 machine.

"It was good to show the customers the immediate cycle data feedback you get per dose at the demo as it was happening live," said Mike Flander, Nexus' new North American technical manager. "It shows the menus and how easy of a system it is to use."

Nexus maintains a new warehouse in St. Michael, Minn., that opened July 1 and houses spare parts and systems. Nexus manufactures its equipment in Austria.

Sanford, Maine-based KRI-Color, a producer of dispersions for silicones (colorants, chemical additives, organic peroxides) also assisted the sunglasses demo with its product line for colorants, specifically designed for use in LSRs.

Kri-Color's hurdle was to customize translucent tint color on the sunglasses in black and green, while adjusting the tint levels so lightness and darkness intensity was achieved.

"With tint/translucent you must have no particulates in the dispersion as every particle must be broken down to its primary specific particle size," said KRI-Color Co-Owner Tom Manello. "Essentially, it must be perfect—if you miss anything it's going to show up. In effect, controlling the color on tint is key versus a solid color, requiring more adjustments."

Roembke Mfg. & Design of Ossian, Ind., provided the demo mold for the sunglasses.

"Silicones are pretty unique because you can change the texture of the tool and effect the feel and look of the molded part without changing materials," said Adam Shaal, Roembke's business development manager. "Many would think that it's two materials, but it's a single shot. (Shin Etsu's) silicone perfectly replicates anything in the mold and it's all about the mold being perfect."