U.S. patent application number 10/143907 was filed with the patent office on 2002-10-31 for photocurable compositions with alicyclic epoxides of high monomer purity.
This patent application is currently assigned to VANTICO INC.. Invention is credited to Fong, John W., Melisaris, Anastasios P., Pang, Thomas H., Renyi, Wang.
Application Number | 20020160309 10/143907 |
Document ID | / |
Family ID | 22000442 |
Filed Date | 2002-10-31 |
United States Patent
Application |
20020160309 |
Kind Code |
A1 |
Pang, Thomas H. ; et
al. |
October 31, 2002 |
Photocurable compositions with alicyclic epoxides of high monomer
purity
Abstract
The present invention relates to novel resin compositions
containing at least one solid or liquid actinic radiation-curable
and cationically polymerizable organic substance, an actinic
radiation-sensitive initiator for cationic polymerization, an
actinic radiation-curable and radical-polymerizable organic
substance and an actinic radiation-sensitive initiator for radical
polymerization. The actinic radiation-curable and cationically
polymerizable organic substance is at least one glycidylether of a
polyhydric aliphatic, alicyclic or aromatic alcohol having at least
three epoxy groups with epoxy equivalent weight between 90 and 800
grams per equivalent, at least one solid or liquid alicyclic
epoxide with an epoxy equivalent weight between 90 and 330 grams
per equivalent having at least two epoxy groups and monomer purity
greater than about 90% by weight, or at least a solid or liquid
epoxycresol novolac or epoxyphenol novolac having epoxy equivalent
weight between 130 and 350, or mixtures thereof. The use of the
above-mentioned cationically polymerizable components substantially
increases the heat deflection temperature of the cured articles
while maintaining high photospeed, accuracy, wetting-recoatability,
water resistance and good side wall finish. The present invention
further relates to a method of producing a cured product,
particularly a three-dimensional article, in which a compositions
described above are treated with actinic radiation.
Inventors: |
Pang, Thomas H.; (Castaic,
CA) ; Melisaris, Anastasios P.; (Stevenson Ranch,
CA) ; Renyi, Wang; (Alhambra, CA) ; Fong, John
W.; (Los Angeles, CA) |
Correspondence
Address: |
LYON & LYON LLP
633 WEST FIFTH STREET
SUITE 4700
LOS ANGELES
CA
90071
US
|
Assignee: |
VANTICO INC.
|
Family ID: |
22000442 |
Appl. No.: |
10/143907 |
Filed: |
May 14, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10143907 |
May 14, 2002 |
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09602172 |
Jun 22, 2000 |
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6413696 |
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09602172 |
Jun 22, 2000 |
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09055832 |
Apr 6, 1998 |
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6100007 |
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Current U.S.
Class: |
430/280.1 ;
264/401; 430/269 |
Current CPC
Class: |
B33Y 70/00 20141201;
B29C 64/106 20170801; G03F 7/0037 20130101; G03F 7/038 20130101;
B33Y 10/00 20141201 |
Class at
Publication: |
430/280.1 ;
430/269; 264/401 |
International
Class: |
G03C 005/00 |
Claims
What is claimed is:
1. A novel resin composition comprising a) 55-90% by weight of at
least one solid or liquid actinic radiation-curable and
cationically polymerizable organic substance; b) 0.05 to 10% by
weight an actinic radiation-sensitive initiator for cationic
polymerization; c) 5% to 25% by weight of an actinic
radiation-curable and radical-polymerizable organic substance; and
(d) 0.02 to 10% by weight an actinic radiation-sensitive initiator
for radical polymerization, wherein component (a) comprises at
least one glycidylether of a polyhydric aliphatic, alicyclic or
aromatic alcohol having at least three epoxy groups with epoxy
equivalent weight between 90 and 800 g/equivalent and at least one
solid or liquid alicyclic epoxide with epoxy equivalent weight
between 80 and 330 having at least two epoxy groups with a monomer
purity of at least about 80% by weight, or mixtures thereof with
the sum total of components (a) through (d) being 100 percent by
weight.
2. A liquid composition according to claim 1 wherein component (a)
comprises the at least one solid or liquid alicyclic epoxide having
at least two epoxy groups, or mixtures thereof, at between 20 and
75% by weight.
3. A liquid composition according to claim 1 wherein component (a)
further comprises not more than 20% by weight of at least one
liquid or solid vinylether compound having at least two
cationically-reactive groups in the molecule or a
hydroxy-functionalized mono(poly)vinylether or mixtures
thereof.
4. A liquid composition according to claim 1 wherein component (a)
further comprises at least one liquid or solid epoxy cresol
novolac, epoxy phenol novolac, oxetane or spiro-ortho ester
compound having at least two cationically-reactive groups in the
molecule, or mixtures thereof.
5. A liquid composition according to claim 1 wherein the at least
one glycidylether of a polyhydric aliphatic, alicyclic or aromatic
alcohol having at least three epoxy groups is between 3 and 90% by
weight of the at least one alicylic epoxide having at least two
epoxy groups.
6. A liquid composition according to claim 5 wherein the at least
one glycidylether of a polyhydric alcohol having at least three
epoxy groups comprises at least 15% by weight of the at least one
alicylic epoxide having at least two epoxy groups.
7. A novel resin composition comprising a) 55-90% by weight of at
least one solid or liquid actinic radiation-curable and
cationically polymerizable organic substance; b) 0.05 to 10% by
weight an actinic radiation-sensitive initiator for cationic
polymerization; c) 5-25% by weight of an actinic radiation-curable
and radical-polymerizable organic substance; and (d) 0.02 to 10% by
weight an actinic radiation-sensitive initiator for radical
polymerization, wherein component (a), comprises of at least one
glycidylether of a polyhydric aliphatic, alicyclic or aromatic
alcohol having at least three epoxy groups with epoxy equivalent
weight between 90 and 800 g/equivalent and at least one solid or
liquid epoxy cresol novolac, or epoxy phenol novolac with epoxy
equivalent weight between 130 and 350 having at least two
functional groups, or mixtures thereof with the sum total of
components (a) through (d) being 100 percent by weight.
8. A liquid composition according to claim 7 wherein component (a)
comprises the at least one solid or liquid epoxy cresol novolac,
epoxy phenol novolac having at least two functional groups, or
mixtures thereof between 2 and 50% by weight.
9. A novel composition according to claim 7 wherein component (a)
further comprises not more than 20% by weight of at least one
liquid or solid vinylether compound having at least two
cationically-reactive groups in the molecule, or a
hydroxy-functionalized mono(poly)vinylether, or mixtures
thereof.
10. A novel composition according to claim 7 wherein component (a)
further comprises at least one liquid or solid alicyclic
polyfunctional epoxide, oxetane or spiro-ortho ester compound
having at least two cationically-reactive groups in the molecule,
or mixtures thereof.
11. A liquid composition according to claim 7 wherein the at least
one glycidylether of a polyhydric aliphatic, alicyclic or aromatic
alcohol having at least three epoxy groups is between 3 and 90% by
weight of the at least one solid or liquid epoxy cresol novolac,
epoxy phenol novolac having at least two functional groups.
12. A curable composition according to claim 7 wherein the at least
one glycidylether of a polyhydric aliphatic, alicyclic or aromatic
alcohol having at least three epoxy groups is at least 15% by
weight of the at least one solid or liquid epoxy cresol novolac,
epoxy phenol novolac having at least two functional groups.
13. A curable composition according to claim 7 wherein the at least
one solid or liquid epoxy cresol novolac or epoxy phenol novolac
having at least two functional groups has an epoxy functionality at
least 4.5.
14. A curable composition according to claim 1 wherein the
composition further comprises: e) 0.5 to about 40 percent by weight
of at least one solid or liquid cationic reactive
modifier-flexibilizer.
15. A curable composition according to claim 14 wherein the at
least one solid or liquid cationic reactive modifier is a reactive
epoxy modifier or reactive vinylether modifier or mixtures
thereof.
16. A curable composition according to claim 14 wherein the
reactive modifier-flexibilizer comprises at least one cationically
reactive bifunctional aliphatic, alicyclic or aromatic compound
containing a chain extension segment connected to the cationic
reactive group with a molecular weight of at least about 100 and
not more than 2000.
17. A curable composition according to claim 7 wherein the
composition further comprises: e) 0.5 to about 40 percent by weight
of at least one solid or liquid cationic reactive
modifier-flexibilizer.
18. A curable composition according to claim 17 wherein the at
least one solid or liquid cationic reactive modifier is a reactive
epoxy modifier or reactive vinylether modifier or mixtures
thereof.
19. A curable composition according to claim 17 wherein the
reactive modifier-flexibilizer comprises at least one cationically
reactive bifunctional aliphatic, alicyclic or aromatic compound
containing a chain extension segment connected to the cationic
reactive group with a molecular weight of at least about 100 and
not more than 2000.
20. A curable composition according to claim 1 wherein the
composition contains about 4 to 30% by weight of a free radically
curable component comprising at least 4% by weight one mono- or
di(meth)acrylate and at least 4% by weight a poly(meth)acrylate
having (meth)acrylate functionality greater than or equal to 3.
21. A method of producing a cured product, in which a composition
according to claim 1 is treated with actinic radiation.
22. A method of producing a cured product, in which a composition
according to claim 7 is treated with actinic radiation.
23. A method for producing three-dimensional shaped articles
comprising: a) treating a radiation-curable composition according
to claim 1 with actinic radiation to form an at least partially
cured layer on the surface of said composition within a surface
region corresponding to a desired cross-sectional area of the
three-dimensional article to be formed, b) covering the at least
partially cured layer produced in step a) with a new layer of said
radiation-curable composition, and c) repeating steps a) and b)
until an article having the desired shape is formed, and
optionally, d) post-curing the resulting article.
24. A method for producing three-dimensional shaped articles
comprising: a) treating a radiation-curable composition according
to claim 7 with actinic radiation to form an at least partially
cured layer on the surface of said composition within a surface
region corresponding to a desired cross-sectional area of the
three-dimensional article to be formed, b) covering the at least
partially cured layer produced in step a) with a new layer of said
radiation-curable composition, and c) repeating steps a) and b)
until an article having the desired shape is formed, and
optionally, d) post-curing the resulting article.
Description
[0001] The present invention relates to a liquid, radiation-curable
composition which is particularly suitable for the production of
three-dimensional shaped articles by means of stereolithography, to
a process for the production of a cured product and, in particular,
for the stereolithographic production of a three-dimensional shaped
article from this composition having a high heat deflection
temperature.
BACKGROUND
[0002] The production of three-dimensional articles of complex
shape by means of stereolithography has been known for a relatively
long time. In this technique the desired shaped article is built up
from a liquid, radiation-curable composition with the aid of a
recurring, alternating sequence of two steps (a) and (b); in step
(a), a layer of the liquid, radiation-curable composition, one
boundary of which is the surface of the composition, is cured with
the aid of appropriate radiation, generally radiation produced by a
preferably computer-controlled laser source, within a surface
region which corresponds to the desired cross-sectional area of the
shaped article to be formed, at the height of this layer, and in
step (b) the cured layer is covered with a new layer of the liquid,
radiation-curable composition, and the sequence of steps (a) and
(b) is repeated until a so-called green model of the desired shape
is finished. This green model is, in general, not yet fully cured
and must therefore, normally, be subjected to post-curing.
[0003] The mechanical strength of the green model (modulus of
elasticity, fracture strength), also referred to as green strength,
constitutes an important property of the green model and is
determined essentially by the nature of the
stereolithographic-resin composition employed. Other important
properties of a stereolithographic-resin composition include a high
sensitivity for the radiation employed in the course of curing and
a minimum curl factor, permitting high shape definition of the
green model. In addition, for example, the precured material layers
should be readily wettable by the liquid stereolithographic-resin
composition, and of course not only the green model but also the
ultimately cured shaped article should have optimum mechanical
properties.
[0004] Another requirement that has recently become a high priority
for stereolithography users is the high temperature performance of
cured articles produced by stereolithography. It is usually
measured by the Heat Deflection Temperature (HDT) or Glass
Transition Temperature (T.sub.g). The HDT value is determined by
the ASTM method D648 applying a load of 66 psi.
[0005] For several years, high temperature performance for
stereolithography produced articles has been achieved by the use of
(meth)acrylate chemistry. This approach primarily entails the use
of various commercially available urethane acrylate derivatives.
EP-802455 of Teijin Seiki Corp. (Oct. 22, 1997) and JP 08323866 of
Takemoto Oil & Fat Co Ltd (Dec. 10, 1996) describe acrylate
urethane compositions for achieving good heat resistance and
strength. However, a major disadvantage of such acrylate urethane
compositions is that polymerization is hindered by atmospheric
oxygen because polymerization is of a radical nature, that the cure
shrinkage is unacceptably large, that the resins are irritant to
the skin, particularly when the viscosity is low (low viscosity is
highly preferred for stereolithography applications). Thus,
acrylate urethane-based compositions show poor practicality for
stereolithography.
[0006] Liquid, radiation-curable compositions for stereolithography
which overcome the abovementioned problems of the acrylate
chemistry are described, for example, in U.S. Pat. No. 5,476,748,
which is incoporated herein by reference. These compositions are
so-called hybrid systems, comprising free-radically and
cationically photopolymerizable components. Such hybrid
compositions comprise at least:
[0007] (A) a liquid difunctional or more highly functional epoxy
resin or a liquid mixture consisting of difunctional or more highly
functional epoxy resins;
[0008] (B) a cationic photoinitiator or a mixture of cationic
photoinitiators;
[0009] (C) a free-radical photoinitator or a mixture of
free-radical photoinitiators; and
[0010] (D) at least one liquid poly(meth)acrylate having a
(meth)acrylate functionality of more than 2,
[0011] (E) at least one liquid cycloaliphatic or aromatic
diacrylate, and
[0012] (F) a certain hydroxy compound that is selected from the
group consisting of OH-terminated polyethers, polyesters and
polyurethanes. Such hybrid systems can optionally further contain
vinyl ether-based resins or other cationically cured components
such as oxetanes, spiro-ortho esters.
[0013] A drawback of commercial cationic or hybrid cationic-radical
stereolithographic compositions is that their cured articles show
HDT values that are much lower than those based on acrylate
chemistry, usually between 40 and 100.degree. C.
[0014] Many hybrid compositions have been developed by companies
for use in stereolithography process systems. For example, U.S.
Pat. No. 5,434,196, assigned on its face to Asahi Denka Kogyo K.
K., discloses resin compositions for so-called optical molding
containing a mixture of epoxy resins and vinylethers, a cationic
initiator, and a mixture of an acrylate compound and a triacrylate
compound.
[0015] To date, there is no scientifically published or universally
accepted term for defining the high temperature hybrid
stereolithography resins. Through marketing brochures of
stereolithography resin maufacturers and presentations in trade
organizations, high temperature hybrid stereolithography resins are
defined as those wherein their cured articles have HDT values over
80 and about 100.degree. C. The highest HDT value ever reported for
commercial hybrid stereolithography resins is about 100.degree.
C.
[0016] Despite all previous attempts, there exists a need for
hybrid stereolithography compositions capable of producing high
temperature performance cured articles for which the photospeed,
accuracy, water resistance are commercially acceptable. Such hybrid
compositions should possess HDT values over those of the existing
ones, especially over 100.degree. C.
SUMMARY OF THE INVENTION
[0017] The present invention relates to novel resin compositions
containing at least one solid or liquid actinic radiation-curable
and cationically polymerizable organic substance, an actinic
radiation-sensitive initiator for cationic polymerization and an
actinic radiation-curable and radical-polymerizable organic
substance. The compositions contain an actinic radiation-sensitive
initiator for radical polymerization. The actinic radiation-curable
and cationically polymerizable organic substance is at least one
glycidylether of a polyhydric aliphatic, alicyclic or aromatic
alcohol having at least three epoxy groups with epoxy equivalent
weight between 90 and 700 grams per equivalent and at least one
solid or liquid alicyclic epoxide with an epoxy equivalent weight
between 80 and 330 grams per equivalent having at least two epoxy
groups, or mixtures thereof having a monomer purity greater than
about 80% by weight.
[0018] The composition preferably contains 55-90%, more preferably
20 and 75% by weight, of the at least one solid or liquid actinic
radiation-curable and cationically polymerizable organic substance,
0.05 to 12% by weight an actinic radiation-sensitive initiator for
cationic polymerization, 5% to 25% by weight of an actinic
radiation-curable and radical-polymerizable organic substance, and
0.02 to 10% by weight, with the sum total of components being 100
percent by weight.
[0019] The actinic radiation-curable and cationically polymerizable
organic substance can contain not more than 20% by weight of at
least one liquid or solid vinylether compound having at least two
cationically-reactive groups in the molecule or a
hydroxy-functionalized mono(poly)vinylether or mixtures
thereof.
[0020] The actinic radiation-curable and cationically polymerizable
organic substance can further contain at least one liquid or solid
epoxy cresol novolac, epoxy phenol novolac, oxetane or spiro-ortho
ester compound having at least two cationically-reactive groups in
the molecule, or mixtures thereof.
[0021] The at least one glycidylether of a polyhydric aliphatic,
alicyclic or aromatic alcohol having at least three epoxy groups is
preferably between about 3 and 90%, more preferably 15% to 90% by
weight of the at least one alicylic epoxide having at least two
epoxy groups.
[0022] A further embodiment of the invention is a novel resin
composition containing at least one solid or liquid actinic
radiation-curable and cationically polymerizable organic substance,
an actinic radiation-sensitive initiator for cationic
polymerization, an actinic radiation-curable and
radical-polymerizable organic substance; and an actinic
radiation-sensitive initiator for radical polymerization. The
actinic radiation-curable and cationically polymerizable organic
substance contains at least one glycidylether of a polyhydric
aliphatic, alicyclic or aromatic alcohol having at least three
epoxy groups with epoxy equivalent weight between 90 and 700
grams/equivalent and at least one solid or liquid epoxy cresol
novolac, or epoxy phenol novolac with epoxy equivalent weight
between about 130 and 350 grams/equivalent having at least two
functional groups, or mixtures thereof.
[0023] The composition preferably contains between about 55-90% by
weight of the at least one solid or liquid actinic
radiation-curable and cationically polymerizable organic substance,
0.05 to 12% by weight an actinic radiation-sensitive initiator for
cationic polymerization, 5-25% by weight of an actinic
radiation-curable and radical-polymerizable organic substance, and
0.02 to 10% by weight an actinic radiation-sensitive initiator for
radical polymerization, with the sum total of the components being
100 percent by weight.
[0024] The composition preferably contains the at least one solid
or liquid epoxy cresol novolac, epoxy phenol novolac having at
least two functional groups, or mixtures thereof between 2 and 50%
by weight. The at least one solid or liquid epoxy cresol novolac or
epoxy phenol novolac more preferably has an epoxy functionality at
least 3. The at least one solid or liquid epoxy cresol novolac or
epoxy phenol novolac most preferably has an epoxy functionality at
least 4.
[0025] The composition can further include not more than 20% by
weight of at least one liquid or solid vinylether compound having
at least two cationically-reactive groups the molecule, or a
hydroxy-functionalized mono(poly)vinylether, or mixtures
thereof.
[0026] The actinic radiation-curable and cationically polymerizable
organic substance further comprises at least one liquid or solid
alicyclic polyfunctional epoxide, oxetane or spiro-ortho ester
compound having at least two cationically-reactive groups in the
molecule, or mixtures thereof.
[0027] The composition preferably contains the at least one
glycidylether of a polyhydric aliphatic, alicyclic or aromatic
alcohol having at least three epoxy groups at between 3 and 90%,
more preferably at least 15% to 90% by weight of the at least one
solid or liquid epoxy cresol novolac, epoxy phenol novolac having
at least two functional groups.
[0028] The composition can further include about 0.5 to about 40
percent by weight of at least one solid or liquid cationic reactive
modifier-flexibilizer. The at least one solid or liquid cationic
reactive modifier is preferably a reactive epoxy modifier or
reactive vinylether modifier or a hydroxy-functionalized vinylether
or mixtures thereof. More preferably, the reactive
modifier-flexibilizer includes at least one cationically reactive
bifunctional aliphatic, alicyclic or aromatic compound containing a
chain extension segment connected to the cationic reactive group
with a molecular weight of at least about 100 and not more than
2000.
[0029] The composition can contain from about 4 to 30% by weight of
a free radically curable component comprising at least 4% by weight
one mono- or di(meth)acrylate and at least 4% by weight a
poly(meth)acrylate having (meth)acrylate functionality greater than
or equal to 3.
[0030] The present invention further relates to a method of
producing a cured product, in which a compositions described above
are treated with actinic radiation. More preferably, the present
invention relates to a method for producing three-dimensional
shaped articles comprising:
[0031] a) treating a radiation-curable composition described above
with actinic radiation to form an at least partially cured layer on
the surface of said composition within a surface region
corresponding to a desired cross-sectional area of the
three-dimensional article to be formed,
[0032] b) covering the at least partially cured layer produced in
step a) with a new layer of said radiation-curable composition, and
c) repeating steps a) and b) until an article having the desired
shape is formed, and optionally, d) post-curing the resulting
article.
DETAILED DESCRIPTION OF THE INVENTION
[0033] The novel compositions herein contain, in the broadest
sense, a mixture of at least one cationically curable compound and
at least one photoinitator for the cationically cured compound(s),
and a selected free-radically curable component, wherein the
composition preferably contains substantially no polyol or
hydroxyl-group containing compounds. The compositions further
optionally contain a free radical photoinitiator/sensitizer and a
cationic reactive modifier.
[0034] The cationically curable liquid or solid compound may
expeditiously be an aliphatic, alicyclic or aromatic polyglycidyl
compound or cycloaliphatic polyepoxide or epoxy cresol novolac or
epoxy phenol novolac compound and which on average possess more
than one epoxide group (oxirane ring) in the molecule. Such resins
may have an aliphatic, aromatic, cycloaliphatic, araliphatic or
heterocyclic structure; they contain epoxide groups as side groups,
or these groups form part of an alicyclic or heterocyclic ring
system. Epoxy resins of these types are known in general terms and
are commercially available.
[0035] Polyglycidyl esters and poly(.beta.-methylglycidyl) esters
are one example of suitable epoxy resins. Said polyglycidyl esters
can be obtained by reacting a compound having at least two carboxyl
groups in the molecule with epichlorohydrin or glycerol
dichlorohydrin or .beta.-methylepichlorohydrin. The reaction is
expediently carried out in the presence of bases. The compounds
having at least two carboxyl groups in the molecule can in this
case be, for example, aliphatic polycarboxylic acids, such as
glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic
acid, sebacic acid or dimerized or trimerized linoleic acid.
Likewise, however, it is also possible to employ cycloaliphatic
polycarboxylic acids, for example tetrahydrophthalic acid,
4-methyltetrahydrophthalic acid, hexahydrophthalic acid or
4-methylhexahydrophthalic acid. It is also possible to use aromatic
polycarboxylic acids such as, for example, phthalic acid,
isophthalic acid, trimellitic acid or pyromellitic acid, or else
carboxyl-terminated adducts, for example of trimellitic acid and
polyols, for example glycerol or
2,2-bis(4-hydroxycyclohexyl)propane, can be used.
[0036] Polyglycidyl ethers or poly(.beta.-methylglycidyl) ethers
can likewise be used. Said polyglycidyl ethers can be obtained by
reacting a compound having at least two free alcoholic hydroxyl
groups and/or phenolic hydroxyl groups with a suitably substituted
epichlorohydrin under alkaline conditions or in the presence of an
acidic catalyst followed by alkali treatment. Ethers of this type
are derived, for example, from acyclic alcohols, such as ethylene
glycol, diethylene glycol and higher poly(oxyethylene) glycols,
propane-1,2-diol, or poly(oxypropylene) glycols, propane-1,3-diol,
butane-1,4-diol, poly(oxytetramethylene) glycols, pentane-1,5-diol,
hexane-1,6-diol, hexane-2,4,6-triol, glycerol,
1,1,1-trimethylolpropane, bistrimethylolpropane, pentaerythritol,
sorbitol, and from polyepichlorohydrins. Suitable glycidyl ethers
can also be obtained, however, from cycloaliphatic alcohols, such
as 1,3- or 1,4-dihydroxycyclohexane,
bis(4-hydroxycyclo-hexyl)methane,
2,2-bis(4-hydroxycyclohexyl)propane or 1,1-bis
(hydroxymethyl)cyclohex-3-- ene, or they possess aromatic rings,
such as N,N-bis (2-hydroxyethyl)aniline or
p,p'-bis(2-hydroxyethylamino)diphenylmethane.
[0037] Particularly important representatives of polyglycidyl
ethers or poly(.beta.-methylglycidyl) ethers are based on phenols;
either on monocylic phenols, for example on resorcinol or
hydroquinone, or on polycyclic phenols, for example on
bis(4-hydroxyphenyl)methane (Bisphenol F), 2,2-bis
(4-hydroxyphenyl)propane (Bisphenol A), or on condensation
products, obtained under acidic conditions, of phenols or cresols
with formaldehyde, such as phenol novolaks and cresol novolaks.
These compounds are particularly preferred as epoxy resins for the
present invention, especially diglycidyl ethers based on Bisphenol
A and Bisphenol F and mixtures thereof.
[0038] Poly(N-glycidyl) compounds are likewise suitable for the
purposes of the present invention and are obtainable, for example,
by dehydrochlorination of the reaction products of epichlorohydrin
with amines containing at least two amine hydrogen atoms. These
amines may, for example, be n-butylamine, aniline, toluidine,
m-xylylenediamine, bis(4-aminophenyl)methane or bis
(4-methylaminophenyl)methane. However, other examples of
poly(N-glycidyl) compounds include N,N'-diglycidyl derivatives of
cycloalkyleneureas, such as ethyleneurea or 1,3-propyleneurea, and
N,N'-diglycidyl derivatives of hydantoins, such as of
5,5-dimethylhydantoin.
[0039] Poly(S-glycidyl) compounds are also suitable as the cationic
curing resin herein, examples being di-S-glycidyl derivatives
derived from dithiols, for example ethane-1,2-dithiol or bis
(4-mercaptomethylphenyl) ether.
[0040] Examples of epoxide compounds in which the epoxide groups
form part of an alicyclic or heterocyclic ring system include
bis(2,3-epoxycyclopentyl) ether, 2,3-epoxycyclopentyl glycidyl
ether, 1,2-bis(2,3-epoxycyclopentyloxy)ethane,
bis(4-hydroxycyclohexyl)methane diglycidyl ether,
2,2-bis(4-hydroxycyclohexyl)propane diglycidyl ether,
3,4-epoxycyclohexyl-methyl 3,4-epoxycyclohexanecarboxylate,
3,4-epoxy-6-methyl-cyclohexylmethyl
3,4-epoxy-6-methylcyclohexanecarboxyl- ate,
di(3,4-epoxycyclohexylmethyl) hexanedioate, di
(3,4-epoxy-6-methylcyclohexylmethyl) hexanedioate,
ethylenebis(3,4-epoxycyclohexane-carboxylate, ethanediol
di(3,4-epoxycyclohexylmethyl) ether, vinylcyclohexene dioxide,
dicyclopentadiene diepoxide or
2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy-
)cyclohexane-1,3-dioxane.
[0041] However, it is also possible to employ epoxy resins in which
the 1,2-epoxide groups are attached to different heteroatoms or
functional groups. Examples of these compounds include the
N,N,O-triglycidyl derivative of 4-aminophenol, the glycidyl
ether/glycidyl ester of salicylic acid,
N-glycidyl-N'-(2-glycidyloxypropyl)-5,5-dimethylhydantoin or
2-glycidyloxy-1,3-bis
(5,5-dimethyl-1-glycidylhydantoin-3-yl)propane.
[0042] Also conceivable is the use of liquid prereacted adducts of
epoxy resins, such as those mentioned above, with hardeners for
epoxy resins. It is of course also possible to use liquid mixtures
of liquid or solid epoxy resins in the novel compositions.
[0043] Examples of cationically polymerizable organic substances
other than epoxy resin compounds include oxetane compounds, such as
trimethylene oxide, 3,3-dimethyloxetane and
3,3-dichloromethyloxethane, 3-ethyl-3-phenoxymethyloxetane, and
bis(3-ethyl-3-methyloxy)butane; oxolane compounds, such as
tetrahydrofuran and 2,3-dimethyl-tetrahydrofur- an; cyclic acetal
compounds, such as trioxane, 1,3-dioxalane and 1,3,6-trioxan
cycloctane; cyclic lactone compounds, such as .beta.-propiolactone
and .epsilon.-caprolactone; thiirane compounds, such as ethylene
sulfide, 1,2-propylene sulfide and thioepichlorohydrin; thiotane
compounds, such as 1,3-propylene sulfide and
3,3-dimethylthiothane.
[0044] Vinyl ethers that can be used in stereolithography
compositions include ethyl vinylether, n-propyl vinylether,
isopropyl vinylether, n-butyl vinylether, isobutyl vinylether,
octadecyl vinylether, cyclohexyl vinylether, butanediol
divinylether, cyclohexanedimethanol divinylether, diethyleneglycol
divinylether, triethyleneglycol divinylether, tert-butyl
vinylether, tert-amyl vinylether, ethylhexyl vinylether, dodecyl
vinylether, ethyleneglycol divinylether, ethyleneglycolbutyl
vinylether, hexanediol divinylether, triethyleneglycol
methylvinylether, tetraethyieneglycol divinylether,
trimethylolpropane trivinylether, aminopropyl vinylether,
diethylaminoethyl vinylether, ethylene glycol divinyl ether,
polyalkylene glycol divinyl ether, alkyl vinyl ether and
3,4-dihydropyran-2-methyl 3,4-dihydropyran-2-carboxylate.
Commercial vinyl ethers include the Pluriol-E200 divinyl ether
(PEG200-DVE), poly-THF290 divinylether (PTHF290-DVE) and
polyethyleneglycol-520 methyl vinylether (MPEG500-VE) all of BASF
Corp.
[0045] Hydroxy-functionalized mono(poly)vinylethers include
polyalkyleneglycol monovinylethers, polyalkylene alcohol-terminated
polyvinylethers, butanediol monovinylether, cyclohexanedimethanol
monovinylether, ethyleneglycol monovinylether, hexanediol
monovinylether, diethyleneglycol monovinylether.
[0046] Another highly important class of vinyl ethers that are
suitable for stereolithography and may be used in the hybrid
flexible stereolithography compositions are all those included in
the U.S. Pat. No. 5,506,087, which is incorporated herein by
reference. More preferred are aromatic or alicyclic vinyl ethers.
As an example, commercial vinylethers include Vectomer 4010,
Vectomer 5015, Vectomer 4020, Vectomer 21010 and Vectomer 2020 of
Allied Signal Corp., Morristown, N.J. Most preferred are Vectomer
4010 and Vectomer 5015.
[0047] Other cationically cured compounds include spiro ortho
esters that are prepared by reacting epoxy compounds with lactone;
ethylenically unsaturated compounds, such as vinylcyclohexane,
n-vinyl-2-pyrrolidone and its various derivatives, isobutylene and
polybutadiene, and derivatives of the above compounds.
[0048] The above cationically polymerizable compounds may be used
alone or as a mixture of two or more thereof depending upon the
desired performance.
[0049] Additional cationically curable commercial products that can
be used herein include:Uvacure 1500, Uvacure 1501, Uvacure 1502,
Uvacure 1530, Uvacure 1531, Uvacure 1532, Uvacure 1533, Uvacure
1534, Uvacure 1561, Uvacure 1562, all commercial products of UCB
Radcure Corp., Smyma, GA; UVR-6105, UVR-6100, UVR-6110, UVR-6128,
UVR-6200, UVR-6216 of Union Carbide Corp., Danburry, Conn.; the
Araldite GY series that is Bisphenol A epoxy liquid resins, the
Araldite CT and GT series that is Bisphenol A epoxy solid resins,
the Araldite GY and PY series that is Bisphenol F epoxy liquids,
the cycloaliphatic epoxides Araldite CY 179 and PY 284, the
Araldite DY and RD reactive diluents series, the Araldite ECN
series of epoxy cresol novolacs, the Araldite EPN series of epoxy
phenol novolacs, all commercial products of Ciba Specialty
Chemicals Corp., the Heloxy 48, Heloxy 44, Heloxy 84 and the other
Heloxy product line, the EPON product line, all of Shell Corp., the
DER series of flexible aliphatic and Bisphenol A liquid or solid
epoxy resins, the DEN series of epoxy novolac resins, all
commercial products of Dow Corp., Celoxide 2021, Celoxide 2021 P,
Celoxide 2081, Celoxide 2083, Celoxide 2085, Celoxide 2000,
Celoxide 3000, Glycidole, AOEX-24, Cyclomer A200, Cyclomer M-100,
Epolead GT-300, Epolead GT-302, Epolead GT-400, Epolead 401,
Epolead 403, (Daicel Chemical Industries Co., Ltd.), Epicoat 828,
Epicoat 812, Epicoat 872, Epicoat CT 508, (Yuka Shell Co., Ltd.),
KRM-2100, KRM-2110, KRM-2199, KRM-2400, KRM-2410, KRM-2408,
KRM-2490, KRM-2200, KRM-2720, KRM-2750 (Asahi Denka Kogyo Co.,
Ltd.).
[0050] It is possible to employ a host of known and industrially
tried and tested cationic photoinitiators for epoxy resins for
purposes of practicing the instant invention. Examples of these
photoinitiators are onium salts with anions of weak
nucleophilicity. Examples thereof are halonium salts, iodosyl salts
or sulfonium salts, sulfoxonium salts, or diazonium salts, as
described for example in U.S. Pat. No. 3,708,296. Other cationic
photoinitiators are metallocene salts.
[0051] An overview of further commonplace onium salt initiators
and/or metallocene salts is offered by "UV-Curing, Science and
Technology", (Editor: S. P. Pappas, Technology Marketing Corp., 642
Westover Road, Stamford, Conn., USA) or "Chemistry & Technology
of UV & EB Formulations for Coatings, Inks & Paints", Vol.
3 (edited by P. K. T. Oldring), which is incorporated herein by
reference.
[0052] Preferred compositions comprise, as a cationic
photoinitiator, a compound of the formula (B-I), (B-II) or (B-III)
1
[0053] in which R.sub.1B, R.sub.2B, R.sub.3B, R.sub.4B, R.sub.5B,
R.sub.6B, and R.sub.7B independently of one another are
C.sub.6-C.sub.18 aryl which is unsubstituted or substituted by
appropriate radicals, and
[0054] A.sup.- is CF.sub.3SO.sub.3.sup.- or an anion of the formula
[LQ.sub.mB].sup.-, where
[0055] L is boron, phosphorus, arsenic or antimony,
[0056] Q is a halogen atom, or some of the radicals Q in an anion
LQ.sub.m.sup.- may also be hydroxyl groups, and
[0057] mB is an integer corresponding to the valency of L enlarged
by 1.
[0058] Examples of C.sub.6-C.sub.18 aryl in this context are
phenyl, naphthyl, anthryl and phenanthryl. In these substituents
present for appropriate radicals are alkyl, preferably
C.sub.1-C.sub.6alkyl, such as methyl, ethyl, n-propyl, isopropyl,
n-butyl, sec-butyl, isobutyl, tert-butyl or the various pentyl or
hexyl isomers, alkoxy, preferably C.sub.1-C.sub.6alkoxy, such as
methoxy, ethoxy, propoxy, butoxy, pentoxy or hexoxy, alkylthio,
preferably C.sub.1-C.sub.6alkylthio, such as methylthio, ethylthio,
propylthio, butylthio, pentylthio or hexylthio, halogen, such as
fluorine, chlorine, bromine or iodine, amino groups, cyano groups,
nitro groups or arylthio, such as phenylthio. Examples of preferred
halogen atoms Q are chlorine and, in particular, fluorine.
Preferred anions LQ.sub.mB are BF.sub.4.sup.-, PF.sub.6.sup.-,
AsF.sub.6.sup.-, SbF.sub.6.sup.- and SbF.sub.5(OH).sup.-.
[0059] Particularly preferred compositions are those comprising as
a cationic photoinitiator a compound of the formula (B-III), in
which R.sub.5B, R.sub.6Band R.sub.7B are aryl, aryl being in
particular phenyl or biphenyl or mixtures of these two groups.
[0060] Further preferred compositions are those comprising as a
photoinitiator a compound of the formula (B-IV) 2
[0061] in which
[0062] cB is 1 or 2,
[0063] dB is 1, 2, 3, 4 or 5,
[0064] X.sub.B is a non-nucleophilic anion, especially
[0065] PF.sub.6.sup.-, AsF.sub.6.sup.-, SbF.sub.6.sup.-,
CF.sub.3SO.sub.3.sup.-, C.sub.2F.sub.5SO.sub.3.sup.-,
n-C.sub.3F.sub.7SO.sub.3.sup.-, n-C.sub.4F.sub.9SO.sub.3.sup.-,
n-C.sub.6F.sub.13SO.sub.3.sup.- and
n-C.sub.8F.sub.17SO.sub.3.sup.-,
[0066] R.sub.8B is a .pi.-arene and
[0067] R.sub.9B is an anion of a .pi.-arene, especially a
cyclopentadienyl anion.
[0068] Examples of .pi.-arenes as R.sub.8B and anions of
.pi.-arenes as R.sub.9B can be found in EP-A-0 094 915. Examples of
preferred .pi.-arenes as R.sub.8B are toluene, xylene,
ethylbenzene, cumene, methoxybenzene, methylnaphthalene, pyrene,
perylene, stilbene, diphenylene oxide and diphenylene sulfide.
Cumene, methylnaphthalene or stilbene are particularly preferred.
Examples of non-nucleophilic anions X.sup.- are FSO.sub.3.sup.-,
anions of organic sulfonic acids, of carboxylic acids or of anions
LQ.sub.mB.sup.-. Preferred anions are derived from partially
fluoro- or perfluoro-aliphatic or partially fluoro- or
perfluoro-aromatic carboxylic acids such as CF.sub.3SO.sub.3.sup.-,
C.sub.2F.sub.5SO.sub.3.sup.-, n-C.sub.3F.sub.7SO.sub.3.sup.-,
n-C.sub.4F.sub.9SO.sub.3.sup.-, n-C.sub.6F.sub.13SO.sub.3.sup.-,
n-C.sub.8F.sub.17SO.sub.3.sup.-, or in particular from partially
fluoro- or perfluoro-aliphatic or partially fluoro- or
perfluoro-aromatic organic sulfonic acids, for example from
C.sub.6F.sub.5SO.sub.3.sup.-, or preferably are anions
LQ.sub.mB.sup.-, such as BF.sub.4.sup.-, PF.sub.6.sup.-, AsF
.sub.6.sup.-, SbF.sub.6.sup.-, and SbF.sub.5(OH).sup.-. Preference
is given to PF.sub.6.sup.-, AsF.sub.6.sup.-, SbF.sub.6.sup.-,
CF.sub.3SO.sub.3.sup.-, C.sub.2F.sub.5SO.sub.3.sup.-,
n-C.sub.3F.sub.7SO.sub.3.sup.-, n-C.sub.4F.sub.9SO.sub.3.sup.-,
n-C.sub.6F.sub.13SO.sub.3.sup.- and
n-C.sub.8F.sub.17SO.sub.3.sup.-.
[0069] The metallocene salts can also be employed in combination
with oxidizing agents. Such combinations are described in EP-A-0
126 712.
[0070] In order to increase the light yield it is possible,
depending on the type of initiator, also to employ sensitizers.
Examples of these are polycyclic aromatic hydrocarbons or aromatic
keto compounds. Specific examples of preferred sensitizers are
mentioned in EP-A-0 153 904.
[0071] More preferred commercial cationic photoinitiators are
UVI-6974, UVI-6970, UVI-6960, UVI-6990 (manufactured by Union
Carbide Corp.), CD-1010, CD-1011, CD-1012 (manufactured by Sartomer
Corp.), Adekaoptomer SP-150, SP-151, SP-170, SP-171 (manufactured
by Asahi Denka Kogyo Co., Ltd.), Irgacure 261 (Ciba Specialty
Chemicals Corp.), CI-2481, CI-2624, CI-2639, CI-2064 (Nippon Soda
Co, Ltd.), DTS-102, DTS-103, NAT-103, NDS-103, TPS-103, MDS-103,
MPI-103, BBI-103 (MIdori Chemical Co, Ltd.). Most preferred are
UVI-6974, CD-1010, UVI-6970, Adekaoptomer SP-170, SP-171, CD-1012,
and MPI-103. The above-mentioned cationic photoinitiators can be
used either individually or in combination of two or more.
[0072] It is possible to employ all types of photoinitiators which
form free radicals given the appropriate irradiation. Typical
representatives of free-radical photoinitiators are benzoins, such
as benzoin, benzoin ethers, such as benzoin methyl ether, benzoin
ethyl ether and benzoin isopropyl ether, benzoin phenyl ether and
benzoin acetate, acetophenones, such as acetophenone,
2,2-dimethoxy-acetophenone and 1,1-dichloroacetophenone, benzil,
benzil ketals, such as benzil dimethylketal and benzil diethyl
ketal, anthraquinones, such as 2-methylanthraquinone,
2-ethylanthra-quinone, 2-tert-butylanthraquinone,
1-chloroanthraquinone and 2-amylanthraquinone, and also
triphenylphosphine, benzoylphosphine oxides, for example
2,4,6-trimethylbenzoyl-diphenylphosphine oxide (Luzirin.RTM. TPO),
bisacylphosphine oxides, benzophenones, such as benzophenone and
4,4'-bis(N,N'-dimethylamino)benzophenone, thioxanthones and
xanthones, acridine derivatives, phenazine derivatives, quinoxaline
derivatives or 1-phenyl-1,2-propanedione 2-O-benzoyl oxime,
1-aminophenyl ketones or 1-hydroxy phenyl ketones, such as
1-hydroxycyclohexyl phenyl ketone, phenyl 1-hydroxyisopropyl ketone
and 4-isopropylphenyl 1-hydroxyisopropyl ketone, all of which
constitute known compounds.
[0073] Particularly suitable free-radical photoinitiators which are
used customarily in combination with a He/Cd laser as light source
are acetophenones, such as 2,2-dialkoxybenzophenones and 1-hydroxy
phenyl ketones, for example 1-hydroxycyclohexyl phenyl ketone or
2-hydroxy-isopropyl phenyl ketone
(=2-hydroxy-2,2-dimethylacetophenone), but especially
1-hydroxy-cyclohexyl phenyl ketone.
[0074] A class of photoinitiators that are commonly employed when
using argon ion lasers comprises the benzil ketals, for example
benzil dimethyl ketal. In particular, the photoinitiator used is an
.alpha.-hydroxy phenyl ketone, benzil dimethyl ketal or
2,4,6-trimethylbenzoyidiphenyl-ph- osphine oxide.
[0075] A further class of suitable photoinitiators constitutes the
ionic dye-counterion compounds, which are capable of absorbing
actinic radiation and of generating free radicals which are able to
initiate the polymerization of the acrylates. The novel
compositions containing ionic dye-counterion compounds can in this
way be cured more variably with visible light in an adjustable
wavelength range of 400-700 nm. Ionic dye-counterion compounds and
their mode of action are known, for example U.S. Pat. Nos.
4,751,102, 4,772,530 and 4,772,541. Examples of suitable ionic
dye-counterion compounds are the anionic dye-iodonium ion
complexes, the anionic dye-pyryllium ion complexes and, in
particular, the cationic dye-borate anion compounds of the
following formula: 3
[0076] in which D.sub.c.sup.+ is a cationic dye and R.sub.1C,
R.sub.2C, R.sub.3C and R.sub.4C independently of one another are
each an alkyl, aryl, alkaryl, allyl, aralkyl, alkenyl, alkynyl, an
alicyclic or saturated or unsaturated heterocyclic group. Preferred
definitions for the radicals R.sub.1C to R.sub.4C can be taken for
example, from EP-A-0 223 587.
[0077] As photoinitiator, the novel compositions preferably include
a 1-hydroxy phenyl ketone, especially 1-hydroxycyclohexyl phenyl
ketone.
[0078] The free radical and cationic photoinitiators are added in
effective quantities, i.e. in quantities from 0.1 to 12,
particularly from 0.5 to 9 percent by weight, based on the overall
quantity of the composition. If the novel compositions are used for
stereolithographic processes, in which laser beams are normally
employed, it is essential for the absorption capacity of the
composition to be matched, by way of the type and concentration of
the photoinitiators, in such a way that the depth of curing at
normal laser rate is from approximately 0.1 to 2.5 mm.
[0079] The novel mixtures may also contain various photoinitiators
of different sensitivity to radiation of emission lines with
different wavelengths to obtain a better utilization of a UV/VIS
light source which emits emission lines of different wavelengths.
In this context it is advantageous for the various photoinitiators
to be selected such, and employed in a concentration such, that
equal optical absorption is produced with the emission lines
used.
[0080] The free radically curable component preferably comprises at
least one solid or liquid poly(meth)acrylate, for example, be di-,
tri-, tetra- or pentafunctional monomeric or oligomeric aliphatic,
cycloaliphatic or aromatic acrylates or methacrylates. The
compounds preferably have a molecular weight of from 200 to
500.
[0081] Examples of suitable aliphatic poly(meth)acrylates having
more than two unsaturated bonds in their molecules are the
triacrylates and trimethacrylates of hexane-2,4,6-triol, glycerol
or 1,1,1-trimethylolpropane, ethoxylated or propoxylated glycerol
or 1,1,1-trimethylolpropane, and the hydroxyl-containing
tri(meth)acrylates which are obtained by reacting triepoxide
compounds, for example the triglycidyl ethers of said triols, with
(meth)acrylic acid. It is also possible to use, for example,
pentaerythritol tetraacrylate, bistrimethylolpropane tetraacrylate,
pentaerythritol monohydroxytriacrylate or -methacrylate, or
dipentaerythritol monohydroxypentaacrylate or -methacrylate.
[0082] It is additionally possible, for example, to use
polyfunctional urethane acrylates or urethane methacrylates. These
urethane (meth)acrylates are known to the person skilled in the art
and can be prepared in a known manner by, for example, reacting a
hydroxyl-terminated polyurethane with acrylic acid or methacrylic
acid, or by reacting an isocyanate-terminated prepolymer with
hydroxyalkyl (meth)acrylates to give the urethane
(meth)acrylate.
[0083] Examples of suitable aromatic tri(meth)acrylates are the
reaction products of triglycidyl ethers of trihydric phenols and
phenol or cresol novolaks containing three hydroxyl groups, with
(meth)acrylic acid.
[0084] The (meth)acrylates used herein are known compounds and some
are commercially available, for example from the SARTOMER Company
under product designations such as SR.RTM.295, SR.RTM.350,
SR.RTM.351, SR.RTM.367, SR.RTM.399, SR.RTM.444, SR.RTM.454 or
SR.RTM.9041.
[0085] Preferred compositions are those in which the free radically
curable component contains a tri(meth)acrylate or a
penta(meth)acrylate.
[0086] Suitable examples of di(meth)acrylates are the
di(meth)acrylates of cycloaliphatic or aromatic diols such as
1,4-dihydroxymethylcyclohexane,
2,2-bis(4-hydroxy-cyclohexyl)propane, bis
(4-hydroxycyclohexyl)methane, hydroquinone,
4,4'-dihydroxybi-phenyl, Bisphenol A, Bisphenol F, bisphenol S,
ethoxylated or propoxylated Bisphenol A, ethoxylated or
propoxylated Bisphenol F or ethoxylated or propoxylated bisphenol
S. Di(meth)acrylates of this kind are known and some are
commercially available.
[0087] Other di(meth)acrylates which can be employed are compounds
of the formulae (F-I), (F-II), (F-III) or (F-IV) 4
[0088] in which
[0089] R.sub.1F is a hydrogen atom or methyl,
[0090] Y.sub.F is a direct bond, C.sub.1-C.sub.6alkylene, --S--,
--O--, --SO--, --SO.sub.2-- or --CO--,
[0091] R.sub.2F is a C.sub.1-C.sub.8alkyl group, a phenyl group
which is unsubstituted or substituted by one or more
C.sub.1-C.sub.4alkyl groups, hydroxyl groups or halogen atoms, or
is a radical of the formula --CH.sub.2--OR.sub.3F in which
[0092] R.sub.3F is a C.sub.1-C.sub.8alkyl group or phenyl group,
and
[0093] A.sub.F is a radical selected from the radicals of the
formulae 5
[0094] Further examples of possible di(meth)acrylates are compounds
of the formulae (F-V), (F-VI), (F-VII) and (F-VIII) 6
[0095] These compounds of the formulae (F-I) to (F-VIII) are known
and some are commercially available. Their preparation is also
described in EP-A-0 646 580.
[0096] Examples of commercially available products of these
polyfunctional monomers are KAYARAD R-526, HDDA, NPGDA, TPGDA;
MANDA, R-551, R-712, R-604, R-684, PET-30, GPO-303, TMPTA, THE-330,
DPHA-2H, DPHA-2C, DPHA-21, D-310, D-330, DPCA-20, DPCA-30, DPCA-60,
DPCA-120, DN-0075, DN-2475, T-1420, T-2020, T-2040, TPA-320,
TPA-330, RP-1040, R-011, R-300, R-205 (Nippon Kayaku Co., Ltd.),
Aronix M-210, M-220, M-233, M-240, M-215, M-305, M-309, M-310,
M-315, M-325, M-400, M-6200, M-6400 (Toagosei Chemical Industry Co,
Ltd.), Light acrylate BP-4EA, BP-4PA, BP-2EA, BP-2PA, DCP-A
(Kyoeisha Chemical Industry Co., Ltd.), New Frontier BPE-4, TEICA,
BR-42M, GX-8345 (Daichi Kogyo Seiyaku Co., Ltd.), ASF-400 (Nippon
Steel Chemical Co.), Ripoxy SP-1506, SP-1507, SP-1509, VR-77,
SP-4010, SP-4060 (Showa Highpolymer Co., Ltd.), NK Ester A-BPE-4
(Shin-Nakamura Chemical Industry Co., Ltd.), SA-1002 (Mitsubishi
Chemical Co., Ltd.), Viscoat-195, Viscoat-230, Viscoat-260,
Viscoat-310, Viscoat-214HP, Viscoat-295, Viscoat-300, Viscoat-360,
Viscoat-GPT, Viscoat-400, Viscoat-700, Viscoat-540, Viscoat-3000,
Viscoat-3700 (Osaka Organic Chemical lndustry Co., Ltd.).
[0097] According to the present invention, it is preferrable that
the radiation-curable and cationically polymerizable organic
component (a) comprise at least one component (a1) that is a
polyfunctional aliphatic, alicyclic or aromatic glycidylether(s)
having at least three epoxy groups per molecule. Component (a1) has
been found to 1) substantially increase the high temperature
performance of the cured article, 2) improve the wet recoatability
of the liquid composition and 3) improve the side wall finish of
the cured article. More preferred compositions contain component
(a1) that is a polyfunctional aliphatic, alicyclic or aromatic
glycidylether, or mixtures thereof having at least three epoxy
groups per molecule with an epoxy equivalent weight (EEW) between
90 and 800. Most preferred are those having an EEW weight between
90 and 650. The triglycidylether of trimethylolpropane, Heloxy 48
of Shell Corp., having an EEW of about 140-160 is one of the most
preferred polyglycidylether compounds. The polyfunctional
glycidylether(s) having at least three epoxy groups in their
molecule preferably comprises between about 2 and 90% by weight the
overall cationic component (a), more preferably, between about 9
and about 60% by weight, most preferably betweeh 10 and 50% by
weight.
[0098] According to the present invention, it is preferrable that
the radiation-curable and cationically polymerizable organic
component (a) comprise at least one component (a2) that is an
alicyclic polyepoxide having at least two epoxy groups per
molecule. Component (a2) has been found to be effective at
increasing the high temperature performance of cured articles when
it is in a very pure form, which means elimination of its dimers or
trimers at the highest possible extent. More preferred compositions
contain component (a2) with a monomer purity of over about 80% and
epoxy equivalent weight between 80 and 330, more preferably between
90 and 300. Most preferred compositions contain component (a2) in a
pure form having epoxy equivalent weight between 100 and 280
wherein dimers or trimers or oligomers are substantially
eliminated. Commercial products having over about 90% monomer
purity to greater than about 94% monomer purity are most preferred.
For example, 3,4-epoxycyclohexylmethyl 3',
4'-epoxycyclohexanecarboxylate (ECEC) having an epoxy equivalent
weight between 130 and 145 with varying degrees of monomer purity
can be purchased through various commercial sources. More preferred
is Araldite CY179 of Ciba Speciality Chemicals containing a limited
percentage of dimers or oligomers, such that the monomer purity is
about 90%. Most preferred is UVR6105 of Union Carbide Corp., which
contains a smaller percentage of oligomers than Araldite CY 179.
The most preferred is Uvacure 1500 of UCB Radcure Corp., which is
the purest ECEC known by the inventors. Table 1 in the example
demonstrate that the high monomer purity of Uvacure 1500 produces a
cured article having an unusually high thermal performance. Even a
small percentage by weight of dimers or trimers in a cycloaliphatic
epoxide, component (a2), can drastically reduce the HDT value of
the cured article. Preferred compositions contain component (a2) at
between 5 to 80% by weight. More preferred compositions contain
component (a2) at between 10 and 75% by weight. Most preferred
compositions contain component (a2) at between 15 to 70% by
weight.
[0099] According to the present invention, it is preferrable that
the radiation-curable and cationically polymerizable organic
component (a) comprise at least one component (a3) that is a solid
or liquid epoxycresol novolac or epoxyphenol novolac having at
least two epoxy groups per molecule. Component (a3) has been found
to be very effective at increasing the high temperature performance
of cured articles when its epoxy functionality becomes higher than
2. The epoxy equivalent weight of component (a3) is between 130 to
350 g/eq. More preferred compositions contain component (a3) that
is epoxycresol novolac or epoxyphenol novolacs having an epoxy
functionality at least about 3. Most preferred are those with epoxy
functionality over about 4 to greater than about 5. For example,
epoxycresol novolac ECN1299 has an epoxy equivalent weight number
between 217 and 244 with an epoxy functionality of about 5.4
(product of Ciba Specilaty Chemicals) and produces a cured article
having high temperature performance. Preferred amounts for
component (a3) is between 3 and 80% by weight. More preferred
amount is between 8 to 75% by weight. The most preferred amount is
between 10 to 55% by weight.
[0100] Component (a) optionally preferably includes vinyl-ether
group containing compounds. Preferred examples are aliphatic
polyalkoxy di(poly)vinylethers, polyalkylene di(poly)vinylethers
and hydroxy-functionalized mono(poly)vinylethers. More preferred
vinylethers are those having aromatic or alicyclic moities in their
molecules. Preferred amounts of the vinylether component is between
0.5 to 20% by weight. More preferred amounts is between 2 to 17% by
weight. Most preferred amounts is between 3 to 14 by weight.
[0101] According to the present invention, it is preferrable that
radiation curable and radically polymerizable organic component (c)
be contained in amounts of 4 to 35% by weight. More referred
compositions contain component (c) between 7 to 30% by weight. Most
preferred are compositions containing component (c) between 8 to
20% by weight. Most preferred compositions also contain 4 to 10% by
weight of at least one liquid or solid poly(meth)acrylate having a
(meth)acrylate functionality greater than or equal to 3, and from 4
to 10% by weight of one or more di(meth)acrylates.
[0102] Preferred compositions contain component (b) that is a
cationic photoinitiator or a mixture of cationic photoinitiators
between 0.05 to 12% by weight. More preferred compositions contain
component (b) between 0.1 to 11% by weight. Most preferred
compositions contain component (b) between 0.15 to 10% by
weight.
[0103] It is preferred for component (d) that is a free-radical
photoinitiator or a mixture of free-radical photoinitiators to be
contained between 0.1 to 10% by weight. More preferred compositions
contain component (d) between 0.3 to 8% by weight. Most preferred
compositions contain component (d) between 0.4 to 7% by weight.
[0104] Preferred, more preferred and most preferred compositions
may contain between 0 to 10% by weight of additives or reactive
diluents.
[0105] To impart flexibility and impact resistance, the novel
compositions herein optionally further include a cationic reactive
modifier (epoxy-, vinylether-, spiro-orthoester- or oxetane-based).
The cationic reactive modifier component imparts flexibility and
impact resistance to the cured article without compromising
photospeed, or accuracy of the liquid composition or water
resistance for the cured article. The selected cationic reactive
modifiers should be at least bifunctional compounds, more
preferably aliphatic, alicyclic and/or aromatic compounds having,
on average, at least two cationically reactive groups per molecule
containing at least one chain extension segment with a molecular
weight of at least about 100 and not more than 2000. Each chain
extension segment is an organic or inorganic chain that connects
the epoxide rings or vinylether groups or other cationically
reactive groups with the core or backbone of the main molecule. The
equivalent weight per epoxide can vary between about 180 and about
2000. The equivalent weight per vinylether group or any other
cationically cured group can vary between about 100 and 1600.
[0106] Cationic reactive modifiers having more than two
cationically reactive groups and a corresponding number of chain
extension segments are preferred. Preferred chain extension
segments are unsubstituted aliphatic or aliphatic substituted with
C.sub.1-C.sub.10alkyl or C.sub.1-C.sub.10alkoxy groups,
unsubstituted alkylene or substituted with C.sub.1-C.sub.10alkyl or
C.sub.1-C.sub.10alkoxy alkylene groups, unsubstituted
cycloaliphatic or substituted cycloaliphatic with C.sub.1-C.sub.10
alkyl or C.sub.1-C.sub.10alkoxy groups, unsubstituted aromatic or
aromatic substituted with C.sub.1-C.sub.10alkyl or
C.sub.1-C.sub.10alkoxy groups, saturated and unsaturated
polyesters, polyethers, polysiloxanes, polysilanes, polycarbonates,
polyalkylene ethers. A chain extension segment having 4 to 60
repeating C.sub.2-C.sub.4alkoxy groups, for example isopropoxy,
propoxy and ethoxy, is most preferred. Similarly, for aromatic
epoxides, the chain extension segment between the glycidyl ether
groups and the aromatic nucleus of polyhydric alcohol should have a
molecular weight of at least about 100 and not more than 2000.
[0107] Also preferred are polyglycidyl esters and
poly(.beta.-methylglycid- yl)esters having chain extension segments
having a molecular weight of at least about 100 and not more than
2000. Said compounds can be obtained by reacting a compound having
at least two carboxyl groups in the molecule with epichlorohydrin
or glycerol dichlorohydrin or .beta.-methylepichlorohydrin.
Likewise, it is possible to employ cycloaliphatic polycarboxylic
acids, for example tetrahydrophthalic acid. It is also possible to
use aromatic polycarboxylic acids such as phthalic
acid,pyromellitic acid, or else carboxyl-terminated adducts, for
example of trimellitic acid and polyols, for example glycerol or
2,2-bis(4-hydroxycyclohexyl)propane.
[0108] Epoxidized oils (e.g. the Union Carbide FLEXOL, LOE or EPO)
having chain extension segments having a molecular weight of at
least about 400 and not more than 3,000 are also preferred
epoxy-based cationic reactive modifiers.
[0109] A more preferred epoxy-based cationic reactive modifier is a
liquid or solid polyglycidyl ether of a polyhydric alcohol or
adducts or polybasic acid thereof with alkylene oxide (e.g.
triglycidyl ether of glycerol chain extended by between five and
fourteen isopropoxy groups per glycidyl ether group). Also
preferred is a dimer acid diglycidylether having an aliphatic
backbone of between about C.sub.15 to about C.sub.150, such as
Heloxy.RTM. 71 having an aliphatic backbone of about C.sub.34,
polyglycol diepoxides having a backbone consisting between about 4
and 50 isopropoxy units, such as Heloxy.RTM. 32, with 7 isopropoxy
groups, polyglycidylethers of castor oil, such as Heloxy.RTM. 505,
all three products are commercially available by Shell Corp.,
Houston, Tex. The most preferred epoxy-based cationic reactive
modifier is a triglycidyl ether of polypropoxylated glycerol having
the following structure: 7
[0110] which is commercially available under the tradename
Heloxy.RTM. 84 from Shell Company, Houston, Tex.
[0111] Other preferred cationic reactive modifiers are based on
liquid or solid vinyl ethers, such as polyalkylene glycol di-(poly)
vinyl ether, tetraethyleneglycol divinylether,
hydroxy-functionalized mono(poly)vinylethers, also cycloaliphatic
or aromatic (di)polyvinyl ethers chain extended with at least one
chain extension segment. Preferred chain extension segments are
unsubstituted aliphatic or aliphatic substituted with
C.sub.1-C.sub.10alkyl or C.sub.1-C.sub.10alkoxy groups,
unsubstituted alkylene or alklylene substituted with
C.sub.1-C.sub.10alkyl or C.sub.10-C.sub.10alkoxy groups,
unsubstituted cycloaliphatic or cycloaliphatic substituted with
C.sub.1-C.sub.10alkyl or C.sub.1-C.sub.10alkoxy groups,
unsubstituted aromatic or aromatic substituted with
C.sub.1-C.sub.10alkyl or C.sub.1-C.sub.10alkoxy groups, saturated
and unsaturated polyesters, polyethers, polysiloxanes, polysilanes,
polycarbonates, polyalkylene ethers. The vinylether-based cationic
reactive modifier should be at least bifunctional.
[0112] A chain extension segment having 4 to 80 repeating
C.sub.2-C.sub.4alkoxy groups, for example isopropoxy, propoxy and
ethoxy, is most preferred.
[0113] Depending on the polarity of the composition, the chain
extension segment can be chosen in such a way that the cationic
reactive modifier is highly compatible with the liquid curable
composition. Such a selection results in, not only an improvement
in elongation and impact resistance, but improved recoatability and
elimination of undesirable phase separation phenomena. In the case
of slightly polar liquid compositions, the chain extension segment
may be an ethoxy or propoxy or isopropoxy or oxytetramethylene or
derivatives thereof. In addition to high flexibility, if there is a
need for imparting water resistance into the composition, then the
aromatic or hydrocarbon or isopropoxy or low ether content chain
extenders are most preferred.
[0114] The cationic reactive modifiers are preferably present in
the overall composition at between about 0.5% to about 60% by
weight, more preferably about 2% to about 50% by weight, most
preferably about 2% to 30 by weight. The solid or liquid reactive
cationically modifiers may be used singly or as a mixture.
[0115] The compositions described above can further include
customary additives for stereolithographic compositions, such as
coloring agents, such as pigments and dyes, antifoaming agents,
leveling agents, thickening agents, flame retardant and
antioxidants.
[0116] In a particularly preferred embodiment, the hybrid
cationically and radically cured composition does not contain any
polyol or hydroxyl group-containing compounds. It has been widely
accepted that hydroxyl group-containing compounds are a required
component for epoxy hybrid compositions used in stereolithography.
It is believed that epoxy formulations do not cure and postcure to
high extent unless the composition contains a certain percentage of
a diol, triol or polyol. This belief is based on the understanding
that the hydroxyl groups react with the epoxy groups during the
epoxy ring opening, and contribute to the formation of a dense
three dimensional network. A recent application WO 97/38354 (Oct.
16, 1997) to DSM Corp., Japan Synthetic Rubber Co., Ltd., Japan
Fine Coatings Co., Ltd. teaches that a diol or trio or polyol
component is necessary to be present in a hybrid liquid composition
at a concentration above a critical one in order the cured articles
to possess good properties. The same patent teaches that "if the
proportion of the polyol component is too low, the aim of
developing the photo-curing characteristic can not be achieved and
these are cases where a three-dimensional object with sufficient
stability in shape and properties can not be produced from the
resin composition". Applicants, however, herein have been able to
obtain highly crosslinked networks by photopolymerizing hybrid
epoxy compositions with no diol or triol or polyol having high heat
deflection temperature values, in excess 110.degree. C.
[0117] If necessary, the resin composition for stereolithography
applications according to the present invention may contain other
materials in suitable amounts, as far as the effect of the present
invention is not adversely affected. Examples of such materials
include radical-polymerizable organic substances other than the
aforementioned cationically polymerizable organic substances;
heat-sensitive polymerization initiators; various additives for
resins such as coloring agents such as pigments and dyes,
antifoaming agents, leveling agents, thickening agents, flame
retardant and antioxidant; fillers such as silica, alumina, glass
powder, ceramic powder, metal powder and modifier resins.
Particular examples of the radical-polymerizable organic substances
include but not limited to compounds that thermally polymerize,
while those of the heat-sensitive polymerization initiator includes
aliphatic onium salts disclosed in Japanese Patent Laid-Open Nos.
49613/1982 and 37004/1983.
[0118] The filler to be used in the present invention is a reactive
or non-reactive, inorganic or organic, powdery, fibrous or flaky
material. The filler material can be organic or inorganic. Examples
of organic filler materials are polymeric compounds,
thermoplastics, core-shell, aramid, kevlar, nylon, crosslinked
polystyrene, crosslinked poly(methyl methacrylate)., polystyrene or
polypropylene, crosslinked polyethylene powder, crosslinked
phenolic resin powder, crosslinked urea resin powder, crosslinked
melamine resin powder, crosslinked polyester resin powder and
crosslinked epoxy resin powder. Examples of inorganic fillers are
mica, glass or silica beads, calcium carbonate, barium sulfate,
talc, glass or silica bubbles, zirconium silicate, iron oxides,
glass fiber, asbestos, diatomaceous earth, dolomite, powdered
metals, titanium oxides, pulp powder, kaoline, modified kaolin,
hydrated kaolin metallic filers, ceramics and composites. Mixtures
of organic and/or inorganic fillers can be used.
[0119] Further examples of preferred fillers are micro crystalline
silica, crystalline silica, amorphous silica, alkali alumino
silicate, feldspar, woolastonite, alumina, aluminum hydroxide,
glass powder, alumina trihydrate, surface treated alumina
trihydrate, alumina silicate. Each of the preferred fillers is
commercially available. The most preferred filler materials are
inorganic fillers, such as mica, Imsil, Novasite, amorphous silica,
feldspar, and alumina trihydrate. It has transparency to UV light,
low tendency to refract or reflect incident light and it provides
good dimensional stability and heat resistance.
[0120] The filler to be used for the resin composition for
stereolithography according to the present invention must satisfy
requirements that it hinders neither cationic nor radical
polymerizations and the filled SL composition has a relatively low
viscosity suitable for the stereolithography process. These fillers
may be used alone or as a mixture of two or more of them depending
upon the desired performance. The fillers used in the present
invention may be neutral acidic or basic. The filler particle size
may vary depending on the application and the desired resin
characteristics. It may vary between 50 nanometers and 50
micrometers.
[0121] The filler material can optionally be surfaced treated with
various compounds-coupling agents. Examples include methacryloxy
propyl trimethoxy silane, beta-(3,4-epoxycyclohexyl)ethyl
trimethoxy silane, gamma-glycidoxy propyl trimethoxy silane and
methyl triethoxy silane. The most preferred coupling agents are
commercially available from Osi Chemicals Corp. and other chemical
suppliers.
[0122] The filler loading is preferably from about 0.5 to about
90%, more preferably from about 5 to about 75%, most preferably
from about 5 to about 60% by weight with respect to the total
weight of the filled resin composition.
[0123] The novel compositions can be prepared in a known manner by,
for example, premixing individual components and then mixing these
premixes, or by mixing all of the components using customary
devices, such as stirred vessels, in the absence of light and, if
desired, at slightly elevated temperature.
[0124] The novel compositions can be polymerized by irradiation
with actinic light, for example by means of electron beams, X-rays,
UV or VIS light, preferably with radiation in the wavelength range
of 280-650 nm. Particularly suitable are laser beams of HeCd, argon
or nitrogen and also metal vapour and NdYAG lasers. This invention
is extended throughout the various types of lasers existing or
under development that are to be used for the stereolithography
process, e.g. solid state, argon ion lasers,etc. The person skilled
in the art is aware that it is necessary, for each chosen light
source, to select the appropriate photoinitiator and, if
appropriate, to carry out sensitization. It has been recognized
that the depth of penetration of the radiation into the composition
to be polymerized, and also the operating rate, are directly
proportional to the absorption coefficient and to the concentration
of the photoinitiator. In stereolithography it is preferred to
employ those photoinitiators which give rise to the highest number
of forming free radicals or cationic particles and which enable the
greatest depth of penetration of the radiation into the
compositions which are to be polymerized.
[0125] The invention additionally relates to a method of producing
a cured product, in which compositions as described above are
treated with actinic radiation. For example, it is possible in this
context to use the novel compositions as adhesives, as coating
compositions, as photoresists, for example as solder resists, or
for rapid prototyping, but especially for stereolithography. When
the novel mixtures are employed as coating compositions, the
resulting coatings on wood, paper, metal, ceramic or other surfaces
are clear and hard. The coating thickness may vary greatly and can
for instance be from 0.01 mm to about 1 mm. Using the novel
mixtures it is possible to produce relief images for printed
circuits or printing plates directly by irradiation of the
mixtures, for example by means of a computer-controlled laser beam
of appropriate wavelength or employing a photomask and an
appropriate light source.
[0126] One specific embodiment of the abovementioned method is a
process for the stereolithographic production of a
three-dimensional shaped article, in which the article is built up
from a novel composition with the aid of a repeating, alternating
sequence of steps (a) and (b); in step (a), a layer of the
composition, one boundary of which is the surface of the
composition, is cured with the aid of appropriate radiation within
a surface region which corresponds to the desired cross-sectional
area of the three-dimensional article to be formed, at the height
of this layer, and in step (b) the freshly cured layer is covered
with a new layer of the liquid, radiation-curable composition, this
sequence of steps (a) and (b) being repeated until an article
having the desired shape is formed. In this process, the radiation
source used is preferably a laser beam, which with particular
preference is computer-controlled.
[0127] In general, the above-described initial radiation curing, in
the course of which the so-called green models are obtained which
do not as yet exhibit adequate strength, is followed then by the
final curing of the shaped articles by heating and/or further
irradiation.
[0128] The term "liquid" in this application is to be equated with
"liquid at room temperature" in the absence of any statement to the
contrary, room temperature being understood as being, in general, a
temperature between 50 and 45.degree. C., preferably between
15.degree. and 30.degree. C.
EXAMPLES BACKGROUND
[0129] Representative embodiments of the present invention will be
described as examples, though the present invention by no means is
limited by them. In the following examples, all parts are by
weight. The formulations indicated in the examples are prepared by
mixing the components, with a stirrer at 20 to 80.degree. C.
(depending on viscosity) until a homogeneous composition is
obtained. Most formulations can be stirred to a homogenous
composition at room temperatures of about 25 to 30.degree. C.
[0130] The physical data relating to the formulations are obtained
as follows: The viscosity of the liquid mixture is determined at
30.degree. C. using a Brookfield viscometer. The mechanical
properties of the formulations are determined on three-dimensional
specimens produced with the aid of an He/Cd or Ar/UV laser. In
particular, the window panes (for measuring photospeed) and the HDT
specimens were built in a 3D Systems SL 350 sterelithography
machine using a solid state laser emitting at 355 nm. The HDT
specimens were UV postcured in a 3D PCA apparatus for 90 minutes
and subsequently thermally postcured at 160.degree. C. for 2 hours.
The HDT value was measured based on the ASTM method D648 under
maximum fiber stress of 66 psi.
[0131] The photosensitivity of the formulations is determined on
so-called window panes. In this determination, single-layer test
specimens are produced using different laser energies, and the
layer thicknesses obtained are measured. The plotting of the
resulting layer thickness on a graph against the logarithm of the
irradiation energy used gives a"working curve". The slope of this
curve is termed D.sub.p (given in mm or mils). The energy value at
which the curve passes through the x-axis is termed E.sub.c (and is
the energy at which gelling of the material still just takes place;
cf. P. Jacobs, Rapid Prototyping and Manufacturing, Soc. of
Manufacturing Engineers, 1992, p. 270 ff.).
[0132] The raw materials used for liquid SL compositions of Table 1
were:
[0133] Trimethylolpropane triglycidylether (Heloxy 48) and
4,4'-cyclohehanedimethanol diglycidylether (Heloxy 107) are
commercial products of Shell Corp., Houston, Tex.
[0134] 1,4-Butanediol diglycidylether (Araldite DY026), cresol
epoxy novolac (ECN1299), epoxy phenol novolac (EPN 9880CH),
3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate
(Araldite CY179), and radical photoinitiator 1-hydroxycyclohexyl
phenyl ketone (Irgacure 184), are all commercial products of Ciba
Specialty Chemicals Corp., Tarrytown, N.Y.
[0135] 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate
(UVAcure1500), is a distilled cycloaliphatic diepoxide, and the
Bisphenol A diglycidylether diacrylate (Ebecryl 3700) are
commercial products of UCB Radcure, Smyrna, Ga.
[0136] Dipentaerythritol monohydroxypentaacrylate (SR 399) and the
cationic photoinitiator CD1010 are commercial products of Sartomer
Corp, Exton, Pa.
[0137] Caprolactone polyester-polyol Tone 0301 is a commercial
product of Union Carbide, Danbury, Conn.
1TABLE 1 Liquid Stereolithography Compositions. Formula # 1 2 3 4 5
6 7 8 Heloxy 48 15.0 30.0 30.0 10.0 10.0 30.0 Heloxy 107 30.0 12.5
12.5 DY 026 30.0 20.0 20.0 ECN 1299 38.2 EPN 9880 38.2 CH UVACure
65.2 50.2 50.2 50.2 50.2 1500 CY 179 50.2 Vectomer 8.0 4010 N3700
6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 SR399 6.0 6.0 6.0 6.0 6.0 6.0 6.0
6.0 I-184 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 CD 1010 5.0 5.0 5.0 5.0
5.0 4.5 4.5 5.0 Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0
108.0 Weight D.sub.p (mils) 5.46 5.48 5.57 5.26 5.59 4.86 4.84 5.39
E.sub.c 8.85 8.54 7.39 6.75 10.05 14.38 21.35 6.06 (mJ/cm.sup.2)
HDT, 2 h at 215 254 129 130 141 240 110 208 160.degree. C.
[0138] Compositions 1 and 2 produce cured articles having excellent
heat deflection temperature values due to the presence of Uvacure
1500, a purified cycloaliphatic epoxide with epoxy equivalent
weight between 130 and 145, in conjuction with Heloxy 48, a
polyglycidylether component having at least three epoxy groups and
epoxy equivalent weight between 140 and 160. Composition 3 shows a
drop of about 125.degree. C. of the HDT value compared to that of
composition 2. This trend was attributed to the replacement of
Heloxy 48 of composition 2 with Heloxy 107, a difunctional
glycidylether in composition 3; note that Heloxy 48 and Heloxy 107
have very similar epoxy equivalent weight, and are contained at the
same percentage by weight. A similar trend was observed in
composition 4 where introduction of the Araldite DY 026, a
difunctional aliphatic epoxide with epoxy equivalent weight of
between 120-135 instead of Heloxy 48 (as in composition 2) may be
responsible for lowering the HDT value to about 130.degree. C.
Composition 5 is similar to composition 2 except that Uvacure 1500
has been replaced with Araldite CY 179. Araldite CY179 is an
alicyclic epoxide having substantially the same chemical structure
as UVAcure 1500. Without being bound by any theories, the lower HDT
value of composition 5 relative to composition 2 may be attributed
to the fact that CY179 has a lower monomer purity than UVAcure1500.
Composition 6 produces excellent heat deflection temperature value
due to the incorporation of ECN 1299 (epoxy cresol novolac), which
has a very high number of reactive functionality (approximately
5.4). Composition 7 containing an epoxy phenol novolac shows HDT
value that is higher than the commercially available hybrid
stereolithography resins having HDT values between 80 and
100.degree. C. Replacement of the EPN9880CH component (epoxy
functionality of 3.6) with another epoxy phenol novolac having
epoxy functionality over 4 would yield a cured article with much
higher HDT value than composition 7. Composition 8 shows that
incorporation of a vinylether, Vectomer 4010, improves the
photospeed of the liquid composition while maintaining high thermal
resistance.
[0139] The above-mentioned scientific comments on SL liquid
compositions of Table 1 were provided in an attempt to follow the
trend of thermal properties based on individual components. Our
intention was neither to distinguish amongst good or bad SL liquid
compositions nor to be bound by any theories. In addition to high
HDT values, the compositions shown above exhibit high photospeed,
good wet-recoatability properties, high water resistance and good
side wall finish.
* * * * *