Liquid radiation curable resins for additive fabrication comprising a triaryl sulfonium borate cationic photoinitiator

Abstract

Liquid radiation curable resins for additive fabrication comprising an R-substituted aromatic thioetber triaryl sulfonmm tetrakis(pentafluorophenyl)borate cationic photoinitiator is disclosed. A process for using the liquid radiation curable resins for additive fabrication and three-dimensional articles made from the liquid radiation curable resins for additive fabrication are also disclosed.

Description

FIELD OF THE INVENTION[0001]The present invention relates to liquid radiation curable resins for additive fabrication processes.BACKGROUND OF THE INVENTION[0002]Additive fabrication processes for producing three dimensional objects are known in the field. Additive fabrication processes utilize computer-aided design (CAD) data of an object to build three-dimensional parts. These three-dimensional parts may be formed from liquid resins, powders, or other materials.[0003]A non-limiting example of an additive fabrication process is stereolithography (SL). Stereolithography is a well-known process for rapidly producing models, prototypes, patterns, and production parts in certain applications. SL uses CAD data of an object wherein the data is transformed into thin cross-sections of a three-dimensional object. The data is loaded into a computer which controls a laser beam that traces the pattern of a cross section through a liquid radiation curable resin composition contained in a vat, so...

AI Technical Summary

Benefits of technology

[0030]The fourth aspect of the instant claimed invention is a liquid radiation curable resin for additive fabrication comprising 5 wt % to about 90 wt %, preferably from 10 wt % to 75 wt %, more preferably from 30 to 75 wt % of inorganic filler, said inorganic filler preferably comprising greater than 80 wt %, preferably greater than 90 wt %, more preferably greater than 95 wt % of silica,

Problems solved by technology

When initially formed, the three-dimensional object is, in general, not fully cured and therefore may be subjected to post-curing, if required.

The use of bulky and expensive gas lasers to cure liquid radiation curable resins is well known.

However, their output power is limited which reduces the amount of curing that occurs during object creation.

In addition, excess heat could be generated at the point of irradiation which may be detrimental to the resin.

Further, the use of a laser requires scanning point by point on the resin which can be time-consuming.

Although LED lamps are available, liquid radiation curable resins suitable for additive fabrication and curable by the use of LED light are not well known commercially.

Although LED lamps are available, photocurable compositions suitable for additive fabrication and curable by the use of LED light are not well known commercially.

Further, the '368 patent fails to disclose the use of an acid generating photoinitiator, such as a cationic photoinitiator.

While the '018 patent and the '186 publication mention UV LEDs and laser diodes as suitable light-emitting centers, they fail to disclose detailed information on photo-activatable building material suitable for LED cure.

Liquid radiation curable resins for additive fabrication that contain cationically polymerizable components but no free-radical polymerizable components are known, however, such resins are generally considered to be too slow for use as rapid prototyping materials.

Many cationic photoinitiators useful in additive fabrication also have poor thermal-stability.

Over time, this small amount of polymerization will create an undesirable increase in the viscosity of the liquid radiation curable resin for additive fabrication.

However, highly filled compositions represent several challenges to the formulator of liquid radiation curable resins for additive fabrication.

A high viscosity liquid radiation curable resin is not desirable in some additive fabrication processes, for instance, stereolithography.

Furthermore, certain highly filled compositions are usually not as photo-stable as non-filled liquid radiation curable resins for additive fabrication.

Achieving good photo-stability is particularly challenging in highly filled liquid radiation curable resins because of additional light scattering effects caused by the filler.

However, in some municipalities, objects fabricated from antimonate based compositions must be disposed of as a hazardous waste or hazardous constituent waste.

For example, antimonate salts can have an undesirable effect in investment casting applications.

Iodonium-borate photoinitiators are available, but suffer from the need to be sensitized at the wavelengths useful for stereolithography and have low thermal-stability.

Sulfonium phosphate photoinitiators are available, but suffer from a poor rate of curing.

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