Oxetane chemistry produces novel SL materials

Edited by the Engineeringtalk editorial team Jul 24, 2006

DSM Somos has introduced three new ABS-like resins representing the second generation of Somos Oxetane Advantage materials.

Historically, acrylate and epoxy chemistries have provided the primary building blocks for most stereolithography materials.

In 2000, DSM Somos used this traditional acrylate-epoxy chemistry to formulate the industry's first clear ABS-like SL resin, WaterClear 10120.

Although WaterClear generated huge commercial interest based on its multipurpose properties and its utility for fit and function testing (particularly fluid flow evaluation), the inherent limitations of its epoxy-based chemistry relative to dimensional consistency and water absorption quickly revealed the need for a new generation of materials.

In 2001, Somos began formulating with a novel technology platform based on oxetane chemistry.

Best described as a "cousin" to epoxy chemistry, oxetanes use a similar cure mechanism to epoxies but can be formulated for: low viscosity - important for faster processing and easier part clean up; faster photo speeds - for higher throughput and higher green strength; and ultra low moisture absorption (high dimensional stability) - particularly important for master patterns used in silicone moulding and QuickCast patterns for investment casting.

This year, DSM Somos has introduced three new ABS-like resins representing the second generation of Somos Oxetane Advantage materials.

Designed for general, multipurpose use, the ProtoGen O-XT series of materials (ProtoGen) uses oxetane chemistry (O-XT) for extra performance (O-XT) in such areas as heat deformation (74C with UV post-cure) and low water absorption.

As the names indicate, ProtoGen O-XT 18120 is a clear material, while ProtoGen O-XT18420 resembles white injection moulded plastic.

Both ProtoGen resins are formulated for high accuracy with very low differential shrinkage, while retaining rapid "draw speed" capabilities.

Coupled with their low viscosity, they deliver robust, efficient build characteristics and are well suited for use in master pattern and fit and function applications.

The clarity of ProtoGen O-XT 18120 also makes it useful for fluid flow evaluation as well as for assembly applications which require external inspection of internal features.

This year's introduction of ProtoCast AF 19120 sets a new performance standard for SL resins in investment casting applications.

Improving on the performance of WaterShed 11120 - the current standard within the investment casting industry - ProtoCast AF boasts ultra low ash (less then 0.01%) due to the elimination of heavy metals.

"Most epoxy-based SL resins contain an antimony-based catalyst which contributes to ash content after burn out", says Somos Technical Service Manager Brian Bauman.

"ProtoCast AF is antimony free".

"These three resins expand the property range of Somos' earlier oxetane materials by adding new levels of accuracy and temperature performance to their already high green strength and dimensional stability", says Somos Marketing Manager Eva Montgomery.

"As a result, RP users now have even more latitude in selecting robust materials that effectively model end-use conditions".

Somos' newest additions to the Oxetane Advantage product family - ProtoGen O-XT 18120 , ProtoGen O-XT 18420 and ProtoCast AF - are completing beta evaluation, with full commercialisation expected later this year.

Availability via distribution channels is planned for early 2007.