Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Patent
1997-09-11
2000-02-15
Hamilton, Cynthia
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
430269, 522 96, 522 92, 264401, G03F 7027, G03F 7028, G03C 908
Patent
active
06025114&
DESCRIPTION:
BRIEF SUMMARY
This invention relates to photocurable compositions, to a process for their polymerisation by means of actinic radiation, to a process for the production of three-dimensional articles from the compositions and to articles so prepared.
It is known that complicated three-dimensional articles can be produced from liquid, photocurable compositions by means of stereolithography. One such process is described in Hull's U.S. Pat. No. 4,575,330. Articles are built up in layers, each new curable layer of resin being firmly attached to the preceding pre-cured layer by preliminary curing by means of UV/VIS light. The overall construction of the three-dimensional article is normally controlled by computer. Photocurable compositions (e.g. liquid resins and resin mixtures) and their use as coating agents, adhesives and photoresists are known. However, the majority of such compositions are not suitable for the production of solidified three-dimensional articles by stereolithography because some are too viscous, whilst others are insufficiently light-sensitive, cure slowly or suffer from excessive shrinking or curling when they are cured.
Ideally photocurable compositions for stereolithography cure reasonably quickly and have a small volume shrinkage in the transition from the liquid to solid state. The so-called "curl factor" is often quoted as a measure of shrinkage induced deformation and a curl factor of 30% is considered by many as being the maximum acceptable, depending or what the article is, and curl factors of below 20% are preferred.
Canadian Patent application 2028541 suggests photocurable compositions for stereolithography. Whilst these compositions do work they tend to have a high curl distortion and high viscosity.
According to the present invention there is provided a liquid composition comprising: of at least 3 and a MW of at least 650; to 4 and a MW of 400 to 10,000; bisphenol A or bisphenol F; and a)+b)+c)+d) add up to 100.
The liquid composition of the invention preferably comprises or consists essentially of 5 to 18 parts, more preferably 8 to 16 parts of component a); 20 to 50 parts, more preferably 25 to 45 parts of component b); 20 to 70 parts, more preferably 30 to 60 parts, especially 35 to 55 parts, more especially 40 to 50 parts of component c); and 1 to 9 parts, more preferably 2 to 8 parts, especially 3 to 7 parts of component d); wherein all parts are by weight and the total number of parts of a)+b)+c)+d) add up to 100.
In a particularly preferred embodiment the liquid composition of the invention comprises or consists essentially of 8 to 16 parts of component a); 25 to 45 parts of component b); 40 to 50 parts of component c); and 3 to 7 parts of component d); wherein all parts are by weight and the total number of parts of a)+b)+c)+d) add up to 100.
Component a) preferably has a MW (i.e. molecular weight) greater than 800, more preferably in the range 880-1200, especially in the range 900-1100.
Examples of suitable compounds which may be used as component (a) are tri-, tetra- and penta-(meth)acrylates (including mixtures thereof), especially those of the formulae I, II, and III: ##STR1## wherein R.sup.1 is a hydrogen atom, methyl, hydroxyl or a group of the formula IV: ##STR2## wherein R.sup.2 is a group of the formula V: ##STR3## wherein n is from 3 to 8, preferably 4 to 8, and R.sup.3 and R.sup.4 are each independently hydrogen or methyl.
Compounds of the formulae I to III which are particularly preferred are those of the formula I in which R.sup.1 is methyl or a group of the formula IV, R.sup.2 is a group of the formula V wherein n is 4 or 5, and R.sup.3 and R.sup.4 are as hereinbefore defined.
As examples of compounds which can be used as component a) there may be mentioned highly propoxylated and ethoxylated 1,1,1-trimethylolpropane triacrylate or trimethacrylate and mixtures thereof. Compounds of this type are known and some are commercially available, for example SARTOMER products of Cray Valley Co. Limited, Newport, Wales and Sartomer Company supply such compounds under the product n
REFERENCES:
patent: 4789620 (1988-12-01), Sasaki et al.
patent: 4945032 (1990-07-01), Murphy et al.
Hunziker et al, 93-245154, English Abstract of EP554219, WPIDS File, Derwent Information LTD, 2 pages, 1998.
Bernard et al, 91-126891, English Abstract of EP 425441, WPIDS File, Derwent Information LTD, 2 pages, 1998.
Lawson John Robert
Popat Ajay Haridas
Hamilton Cynthia
Zeneca Limited
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