U.S. patent application number 10/623270 was filed with the patent office on 2005-01-20 for systems and methods for using multi-part curable materials.
Invention is credited to Kasperchik, Vladek P., Kramer, Laura, Lambright, Terry M..
Application Number | 20050012247 10/623270 |
Document ID | / |
Family ID | 33477145 |
Filed Date | 2005-01-20 |
United States Patent
Application |
20050012247 |
Kind Code |
A1 |
Kramer, Laura ; et
al. |
January 20, 2005 |
Systems and methods for using multi-part curable materials
Abstract
Solid freeform fabrication (SFF) systems for producing a
three-dimensional object and methods of producing three-dimensional
objects are disclosed. The SFF system includes a dispensing system
and a curing system. The dispensing system is adapted to dispense a
radiation initiator and a build material. The radiation initiator
and the build material are stored separately in the dispensing
system and are dispensed separately. The curing system cures the
radiation initiator and the build material after each has been
dispensed.
Inventors: |
Kramer, Laura; (Corvallis,
OR) ; Lambright, Terry M.; (Corvallis, OR) ;
Kasperchik, Vladek P.; (Corvallis, OR) |
Correspondence
Address: |
HEWLETT PACKARD COMPANY
P O BOX 272400, 3404 E. HARMONY ROAD
INTELLECTUAL PROPERTY ADMINISTRATION
FORT COLLINS
CO
80527-2400
US
|
Family ID: |
33477145 |
Appl. No.: |
10/623270 |
Filed: |
July 18, 2003 |
Current U.S.
Class: |
264/401 ;
700/119 |
Current CPC
Class: |
B33Y 10/00 20141201;
B29C 64/112 20170801; B33Y 70/00 20141201 |
Class at
Publication: |
264/401 ;
700/119 |
International
Class: |
G06F 019/00; B29C
035/04 |
Claims
At least the following is claimed:
1. A solid freeform fabrication system for producing a
three-dimensional object, comprising: a dispensing system adapted
to dispense a radiation initiator and a build material, the
radiation initiator and the build material being stored separately
in the dispensing system, the radiation initiator and the build
material being dispensed separately; and a curing system operative
to cure the radiation initiator and the build material after each
have been dispensed.
2. The solid freeform fabrication system of claim 1, wherein the
dispensing system includes at least one ink-jet printhead.
3. The solid freeform fabrication system of claim 2, wherein a
first ink-jet printhead includes the radiation initiator in a first
compartment and the build material in a second compartment.
4. The solid freeform fabrication system of claim 2, wherein a
first ink-jet printhead includes the radiation initiator and a
second ink-jet printhead includes the build material.
5. The solid freeform fabrication system of claim 1, wherein the
radiation initiator is an ultraviolet (UV) initiator.
6. The solid freeform fabrication system of claim 5, wherein the UV
initiator has a viscosity less than 70 centipoise at a temperature
below about 200.degree. C.
7. The solid freeform fabrication system of claim 5, wherein the UV
initiator has a viscosity less than 20 centipoise at a temperature
below about 120.degree. C.
8. The solid freeform fabrication system of claim 5, wherein the UV
initiator is selected from a free radical initiator, a cationic
initiator, and combinations thereof.
9. The solid freeform fabrication system of claim 5, wherein the UV
initiator includes a colorant.
10. The solid freeform fabrication system of claim 1, wherein the
build material has a viscosity less than 70 centipoise at a
temperature below about 200.degree. C.
11. The solid freeform fabrication system of claim 1, wherein the
build material has a viscosity less than 20 centipoise at a
temperature below about 120.degree. C.
12. The solid freeform fabrication system of claim 1, wherein the
build material is selected from acrylic compounds, compounds having
one or more epoxy substituents, one or more vinyl ether
substituents, vinylcaprolactam, vinylpyrrolidone, urethanes, and
combinations thereof.
13. The solid freeform fabrication system of claim 1, wherein the
build material includes a dye.
14. The solid freeform fabrication system of claim 1, further
comprising a computer control system operative to control the
dispensing system and the curing system.
15. The solid freeform fabrication system of claim 1, wherein the
curing system comprises an ultraviolet curing system.
16. A method of producing a three-dimensional object, comprising
the steps of: providing a radiation initiator; providing a build
material, wherein the radiation initiator and the build material
are separated from each other; dispensing the radiation initiator
and the build material onto a build platform independently, wherein
the radiation initiator and the build material are commingled to
form a multi-part radiation curable material; and curing the
multi-part radiation curable material to produce the
three-dimensional object.
17. The method of producing a three-dimensional object of claim 16,
further comprising: heating the build material to a temperature of
about 40 to 200.degree. C.
18. The method of producing a three-dimensional object of claim 16,
further comprising: heating the build material to a temperature of
about 70 to 120.degree. C.
19. The method of producing a three-dimensional object of claim 16,
wherein dispensing includes: dispensing a layer of the build
material; and dispensing a layer of the radiation initiator onto
the layer of the build material thereby forming the multi-part
radiation curable material.
20. The method of producing a three-dimensional object of claim 16,
wherein dispensing includes: dispensing a layer of the radiation
initiator; and dispensing a layer of the build material onto the
layer of radiation initiator thereby forming the multi-part
radiation curable material.
21. The method of producing a three-dimensional object of claim 16,
wherein dispensing includes: dispensing the build material in a
spaced manner; and dispensing the radiation initiator within the
spaces between the build material, wherein the build material and
the radiation initiator form a layer of commingled build material
and radiation initiator thereby forming the multi-part radiation
curable material.
22. The method of producing a three-dimensional object of claim 16,
further comprising: mixing the radiation initiator and the build
material using ultrasonic energy.
23. The method of producing a three-dimensional object of claim 16,
wherein dispensing the UV initiator and the build material is
performed sequentially.
24. The method of producing a three-dimensional object of claim 16,
wherein dispensing the radiation initiator and the build material
is performed simultaneously.
25. The method of producing a three-dimensional object of claim 16,
further comprising means for controlling the temperature of the
build platform.
26. The method of producing a three-dimensional object of claim 16,
wherein the radiation initiator is an ultraviolet initiator.
27. The method of producing a three-dimensional object of claim 16,
wherein dispensing the radiation initiator and the build material
further comprises: dispensing the radiation initiator from a first
ink-jet printhead and dispensingthe build material from a second
ink-jet printhead.
Description
BACKGROUND
[0001] Solid freeform fabrication (SFF) or layer manufacturing (LM)
is a fabrication technology that builds an object of any complex
shape layer by layer or point by point without using a pre-shaped
tool (die or mold). This process begins with creating a Computer
Aided Design (CAD) file to represent the geometry of a desired
object. SFF technology enables direct translation of the CAD image
data into a three-dimensional object. SFF technology can be used in
applications such as verifying CAD database, evaluating design
feasibility, testing part functionality, assessing aesthetics,
checking ergonomics of design, aiding in tool and fixture design,
creating conceptual models and sales/marketing tools, generating
patterns for investment casting, reducing or eliminating
engineering changes in production, and providing small production
runs.
[0002] One SFF technique involves adding or depositing a build
composition to form predetermined areas of a layer essentially
point-by-point; but a multiplicity of points may be deposited at
the same time in some techniques (e.g., ink-jet technology). These
predetermined areas together constitute a thin section of a
three-dimensional object as defined by a CAD geometry. Successive
layers are then deposited in a predetermined sequence with a layer
being affixed to its adjacent layers forming an integral three
dimensional, multi-layer object.
[0003] Typically, an SFF system includes a dispensing system such
as an inkjet dispensing system, a curing system, and a build
platform. The build composition is stored within a compartment of
the inkjet dispensing system as a mixture of an initiator and a
build material. The build composition is dispensed (i.e., jetted)
onto the build platform from an ink-jet printhead of the ink-jet
dispensing system.
[0004] Currently, the build compositions used in the SFF processes
are limited to low viscosity materials (ie., typically lower than
20 centipoise (cps) for good jetting) so that the build composition
can be accurately dispensed. Viscosity is an important parameter
for dispensing materials because materials having a high viscosity
are difficult to dispense. One way to overcome problems associated
with viscosity is to increase the dispensing temperature of the
material. However, some of these build compositions degrade at the
higher temperatures. In addition, heating the build compositions
may initiate polymerization of the build composition prior to being
dispensed. Therefore, build compositions with high viscosities that
are unstable at higher jetting temperatures cannot be used.
SUMMARY
[0005] Briefly described, embodiments of this disclosure include
solid freeform fabrication (SFF) systems for producing
three-dimensional objects. One exemplary SFF system, among others,
includes a dispensing system and a curing system. The dispensing
system is adapted to dispense a radiation initiator and a build
material. The radiation initiator and the build material are stored
separately in the dispensing system and are dispensed separately.
The curing system cures the commingled radiation initiator and the
build material after each has been dispensed.
[0006] Methods of producing three-dimensional objects are also
provided. One exemplary method includes, among others: providing a
radiation initiator; providing a build material, wherein the
radiation initiator and the build material are separated;
dispensing the radiation initiator and the build material onto a
build platform independently, wherein the radiation initiator and
the build material are commingled to form a multi-part radiation
curable material; and curing the multi-part radiation curable
material to form the three-dimensional object.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Many aspects of the invention can be better understood with
reference to the following drawings. The components in the drawings
are not necessarily to scale. Moreover, in the drawings, like
reference numerals designate corresponding parts throughout the
several views.
[0008] FIG. 1 illustrates an embodiment of a solid freeform
fabrication (SFF) system.
[0009] FIG. 2 illustrates a perspective view of an embodiment of a
SFF apparatus.
[0010] FIG. 3 is a representative flow diagram for forming an
object using the embodiment of the SFF system shown in FIGS. 1 and
2.
[0011] FIG. 4A illustrates a layered dispensing process for use in
the SFF system shown in FIGS. 1 and 2, while FIG. 4B illustrates an
alternating dispensing process for use in the embodiment of the SFF
system shown in FIGS. 1 and 2.
DETAILED DESCRIPTION
[0012] Multi-part radiation curable materials, methods of
application thereof, and systems for using the multi-part radiation
curable materials are provided. In particular, the embodiments
relate to the use of multi-part radiation curable materials in the
manufacture of three-dimensional objects by solid freeform
fabrication (SFF) systems and methods. The term three-dimensional
object refers to objects that are sufficiently rigid to maintain a
fixed volume and shape to an extent, which is appropriate for use
in SFF systems.
[0013] The multi-part radiation curable material includes, but is
not limited to, one or more build materials and one or more
radiation initiators. One embodiment of the multi-part radiation
curable material is a two-part radiation curable material that
includes, but is not limited to, a build material and a radiation
initiator.
[0014] The multi-part radiation curable materials are stored
separately within the SFF system and are dispensed in an
independent manner onto a build platform. An advantage of the SFF
systems includes the ability to dispense the build material at
higher temperatures than previously possible. This allows higher
molecular weight components to be used since their relatively high
viscosity can be overcome by heating the components to a higher
temperature. In this regard, the use of higher molecular weight
build materials should result in better mechanical properties than
previously obtained. In addition, since the components are stored
separately, the shelf-life of the build material should be
longer.
[0015] FIG. 1 illustrates a block diagram of a representative SFF
system 10 that includes a computer control system 12, a dispensing
system 14, and a conventional curing system 16. FIG. 2 illustrates
a perspective view of the SFF system 10 shown in FIG. 1. The
computer control system 12 includes a process control system that
is adapted to control the dispensing system 14, the curing system
16 (e.g., a ultraviolet or visible radiation curing system), and
optionally a positioning system and a build platform temperature
control system. In addition, the computer control system 12
includes, but is not limited to, a Computer Aided Design (CAD)
system 18 or other SSF CAD-related systems.
[0016] The dispensing system 14 includes, but is not limited to,
conventional ink-jet technologies and conventional coating
technologies. Ink-jet technology, such as drop-on-demand and
continuous flow ink-jet technologies, can be used to dispense
chemical compositions onto a build platform 20 (FIG. 2). The
dispensing system 14 can include at least one conventional ink-jet
printhead (e.g., thermal ink-jet printhead and/or a piezo ink-jet
print head) adapted to dispense (e.g., jet) one or more chemical
compositions through one or more of a plurality of ink-jet
printhead dispensers. In addition, the ink-jet printhead can
include a plurality of ink-jet compartments (e.g., tanks or wells
for containing the components) that are capable of holding the
multi-part radiation curable materials and are fluidically coupled
to the ink-jet printhead dispensers. The ink-jet printhead
dispenser can be heated to assist in dispensing viscous chemical
compositions. For example, the inkjet printhead dispenser can be
heated up to about 200.degree. C., and preferably in the range of
70 to 120.degree. C.
[0017] In one embodiment, the dispensing system 14 includes a
separate ink-jet printhead for each component of the multi-part
radiation curable material. For example, a two-part radiation
curable material may include two ink-jet printheads, where one
holds a radiation initiator and one holds a build material. In
another example, a three-part radiation curable material may
include three ink-jet printheads, where one holds a radiation
initiator, a second holds a first build material, and the second
includes a second build material. Disposing the components of the
multi-part radiation curable material into different ink-jet
printheads allows the components to be heated to different
temperatures, which is advantageous when the viscosity of the build
material is increased to enhance the dispensement of the build
material.
[0018] The SFF system 10 can be incorporated into processes that
are used to fabricate or construct three-dimensional objects in an
iterative layered process. The computer control system 12 is
capable of being selectively adjusted to control the output from
the dispenser system 14, which controls the thickness and pattern
of each component in each layer of the iterative process.
[0019] The radiation initiator and the build material can be
dispensed onto the build platform in a variety of patterns, two of
which are discussed in more detail in reference to FIGS. 4A and 4B
below. The patterns can take the form of, but not limited to,
alternating layers of the radiation initiators and build materials,
alternating offset-checkerboard layers of the radiation initiators
and build materials, and alternating side-by-side strips of the
radiation initiators and build materials. In addition, other
patterns are possible using two or more printheads. Moreover, the
patterns of the components of the multi-part radiation curable
material can vary depending on the volume or drop-size of the
dispensed components. In this regard, multiple ink-jet printhead
passes (e.g., scans) across the build platform 20 can be conducted
to achieve the appropriate spacing of the components of the
multi-part radiation curable material.
[0020] In general, the volume (e.g., drops) of the radiation
initiator and the build material are from about 0.1 picoliters to
500 picoliters, about 0.1 picoliters to 100 picoliters, and about
0.1 picoliters to 35 picoliters. However, the desirable ejected
volume of the radiation initiator and the build material depends on
a number of factors such as, but not limited to, the concentration,
the viscosity, and the chemical characteristics of the radiation
initiators; the concentration, the viscosity, and the chemical
characteristics of the build materials, the temperature of the
build platform, the ratio between the radiation initiators and the
build materials, the desired resolution (e.g., 600 drops per inch),
and the design of the print-head firing chamber.
[0021] The multi-part radiation curable material includes chemicals
that are compatible for use with ink-jet technologies. The
multi-part radiation curable material can be a multi-part
ultraviolet (UV) radiation curable material or a multi-part visible
radiation curable material. The preferred embodiment is a two-part
UV curable material that includes, but is not limited to, a UV
initiator and build material. FIG. 3 and FIGS. 4A and 4B refer to a
two-part UV curable material, however, the same principals can be
adopted for multi-part radiation curable materials.
[0022] FIG. 3 is a flow diagram describing a representative method
30 for forming an object using the SFF system 10. The UV initiator
and the build material are provided, as shown in block 32. In
particular, the UV initiator and the build material are stored
separately in the dispensing system 14. For example, the UV
initiator and the build material can be stored in different
compartments of a single ink-jet printhead or stored in different
ink-jet printheads. The UV initiator and the build material are
dispensed through different ink-jet printhead dispensers either
simultaneously or in a step-wise manner, as shown in block 34. The
UV initiator and the build material are commingled on the build
platform 20 of the SFF system 10 to form the two-part UV curable
material, as shown in block 36. In addition, ultrasonic energy can
be used to mix the UV initiator and the build material to enhance
commingling of the UV initiator and the build material.
[0023] After one or more layers of the UV initiator and the build
material are dispensed (e.g., simultaneously or sequentially) onto
the build platform 20, the curing system 16 can be used to cure, or
partially cure, the two-part UV curable material, as shown in block
38. Then the process is repeated as necessary to produce the object
of interest in a layer-by-layer fashion. To enhance layer-to-layer
adhesion, it may be useful to only partially cure each layer during
the fabrication process. A full cure could be accomplished by
placing the object in a light box after removal from the
fabrication tool. In addition, the curing process can be performed
after the layers of the multi-part radiation curable material are
dispensed on the build platform 20 (e.g., flood exposure or scan
exposure). Furthermore, the curing process can be performed in a
substantially contemporaneous manner by scan exposing the
multi-part radiation curable material as the radiation initiator
and build material are dispensed onto the build platform 20.
[0024] FIG. 4A illustrates a layered dispensing process of the
build material 46 and the UV initiator 48 onto the build platform
20. The build material 46 and the UV initiator 48 are dispensed
from an ink-jet printhead 42 having two compartments 44a and 44b.
First, a layer of the build material 46 is dispensed onto the build
platform 20, then a layer of UV initiator 48 is dispensed onto the
layer of the build material 46. The build material 46 and the UV
initiator 48 are cured to form layer 50a. Subsequently, another
layer of the build material 46 is dispensed onto the cured layer
50a, then another layer of the UV initiator 48 is dispensed onto
the layer of the build material 46. The build material 46 and the
UV initiator 48 are cured to form layer 50b. This process continues
until the object to be formed is complete. It should be noted that
the order in which the build material 26 and the UV initiator are
dispensed could be reordered (e.g., reversed).
[0025] FIG. 4B illustrates an alternating dispensing process
dispensing the build material 46 and the UV initiator 48 onto the
build platform 20. The build material 46 and the UV initiator 48
are dispensed from an ink-jet printhead 42 having two compartments
44a and 44b. The build material 46 is dispensed onto the build
platform 20 in a spaced manner so that the UV initiator 48 can be
dispensed within the spaces between the build material 46. Next,
the build material 46 and the UV initiator 48 are cured to form
layer 62a. Subsequently, the build material 46 is dispensed onto
the cured layer 62a in a spaced manner so that the UV initiator 48
can be dispensed within the spaces between the build material 46.
The build material 46 and the UV initiator 48 are cured to form
layer 62b. This process continues until the object to be formed is
complete.
[0026] In general, the radiation initiator and/or the build
material can be carried and/or dissolved into a liquid vehicle that
is compatible with ink-jet technologies. For example the liquid
vehicle can include, but is not limited to, water, solvents,
biocides, and sequestering agents.
[0027] In one embodiment, the radiation initiator can be dissolved
in one or more solvents, such as, but not limited to, inert
volatile solvents such as aliphatic and aromatic hydrocarbons of
lower molecular weight, volatile alcohols, ethers, and esters, and
high boiling point plasticizers (e.g., dibutyl phthalate). It's
desirable that the solvent either evaporate quickly (within time
necessary to deposit few layers) or is non-volatile enough to stay
indefinitely long within the cured two-part radiation material.
[0028] In the embodiment described directly above, the volume of
the radiation initiator relative to the volume of the build
material dispensed onto the build platform 20 should be about 1
part radiation initiator to 100 parts of the build material,
although in some embodiments it may be 1 part of the radiation
initiator to 10 parts of the build material, while in still others
it may be 1 par of the radiation initiator to 1 part of the build
material. The ratio of the volumes of the components can be
controlled by the drop volume and/or the number of drops of the
components.
[0029] In other embodiments, the radiation initiator can be
dissolved in a solvent such as, but not limited to, low reactivity
monomers/low viscosity monomers, such as low molecular weight
monofunctional alkyl acrylates and alkyl methacrylates (e.g., allyl
methacrylate, isodecyl acrylate and methacrylate, isooctyl
acrylate), hydroxyalkyl acrylates and methacrylates (e.g.,
2-hydroxyethyl methacrylate), glycidyl methacrylate, isobomyl
acrylate, and the like. In particular, monofunctional monomer
solvents are preferred to dissolve the radiation initiator, because
monofunctional monomers provide better stability than di- and
tri-functional monomers and are less likely to cross-link. In
addition, low viscosity monomers are preferred as solvents for
radiation initiators so that the mixture can be dispensed at a
lower temperature. In these embodiments, the solvent participates
in the polymerization reaction and becomes part of the multi-part
radiation curable material.
[0030] In the embodiment described directly above, the volume of
the radiation initiator relative to the volume of the build
material dispensed onto the build support 20 should be about 10 to
100 parts of the radiation initiator to about 100 parts of the
build material, while in others it may be about 50 parts of the
radiation initiator to 100 parts of the build material. The ratio
of the volumes of the components can be controlled by the drop
volume and/or the number of drops of the components.
[0031] In general, the radiation initiator and the build material
have the characteristic that the chemical has a viscosity (i.e., a
jettable viscosity) less than 70 cps at a temperature below about
200.degree. C. and preferably less than 20 cps at a temperature
below about 100.degree. C.
[0032] In addition, the radiation initiator and the build material
should be able to react to form a "tack free" layer within about 5
seconds to 10 minutes at a temperature below about 100.degree. C.
Preferably, the radiation initiator and the build material should
be able to react to form a "tack free" layer within about 5 seconds
to 1 minute at a temperature below about 60.degree. C. The term
"tack free" is defined as the point where the crosslinking/chain
growth reaction has progressed such that the resulting material is
no longer tacky to the touch. It does not imply that curing/chain
growth is complete.
[0033] As is known in the art, the viscosity of the build material
can generally be lowered by increasing its temperature. Therefore,
the inkjet printhead can be heated to lower the viscosity of the
build material. The use of higher temperatures can allow more
viscous higher molecular weight materials to be used in the build
material, which can provide for more desirable mechanical
properties of the solid three-dimensional object upon cooling.
However, the ink-jet printhead should not be heated to temperatures
that exceed: (a) the boiling point of the build material; (b) the
temperature of thermal decomposition of the build material used;
and (c) the temperature of the build material thermal
activation.
[0034] In general, the radiation initiator and/or the build
material can include additional chemical components such as, but
not limited to, colorants (e.g., dyes, pigments, inks),
dispersants, and catalysts to optimize the reaction time of the
multi-part radiation curable material to obtain the proper balance
of cure rate and layer-to-layer adhesion.
[0035] The UV initiator can indude chemicals such as, but not
limited to, a free radical initiator, a cationic initiator, or
combinations thereof. The free-radical initiator includes compounds
that produce a free radical on exposure to UV radiation. The
free-radical is capable of initiating a polymerization reaction.
Exemplar free-radical initiators include, but are not limited to,
benzophenones (e.g., benzophenone, methyl benzophenone, Michler's
ketone, and xanthones), acylphosphine oxide type free radical
initiators (e.g., 2,4,6-trimethylbenzoyldiphenyl phosphine oxide
(TMPO), 2,4,6-trimethylbenzoylethoxyphenyl phosphine oxide (TEPO),
and bisacylphosphine oxides (BAPO's)), azo compounds (e.g., AlBN),
benzoins and bezoin alkyl ethers (e.g., benzoin, benzoin methyl
ether and benzoin isopropyl ether).
[0036] The free-radical initiator can be used alone or in
combination with a co-initiator. Co-initiators are used with
initiators that need a second molecule to produce a radical that is
active in UV-systems. For example, benzophenone uses a second
molecule, such as an amine, to produce a reactive radical. A
preferred class of co-initiators are alkanolamines such as, but not
limited to, triethylamine, methyldiethanolamine and triethanolamine
Suitable cationic initiators include, but are not limited to,
compounds that form aprotic acids or Bronsted acids upon exposure
to UV light sufficient to initiate polymerization. The cationic
initiator used may be a single compound, a mixture of two or more
active compounds, or a combination of two or more different
compounds (e.g., co-initiators). Exemplary cationic initiators
include, but are not limited to, aryidiazonium salts,
diaryliodonium salts, triarylsulphonium salts, and triarylselenium
salts.
[0037] The build material can include compounds such as, but not
limited to, acrylic compounds, compounds having one or more epoxy
substituents, one or more vinyl ether substituents,
vinylcaprolactam, vinylpyrolidone, urethanes, and combinations
thereof. In particular, monomers of these compounds can be used as
the build material. In addition, oligomers of these compounds,
which may not have been considered previously because of their high
viscosity, can be used as the build material. In this regard, the
increased viscosity latitude allows us to start with higher
molecular weight build materials, which may result in better
mechanical properties (e.g., material stiffness/flexibility and
strength, and resistance to impact) in the final three-dimensional
object. One skilled in the art could select build materials that
satisfy the desired mechanical properties of a particular
application.
[0038] Suitable acrylic compounds for the build material can
include, but are not limited to, an acrylic monomer, an acrylic
oligomer, an acrylic crosslinker, or combinations thereof. An
acrylic monomer is a monofunctional acrylated molecule, which can
be, for example, esters of acrylic acid and methacrylic acid. An
acrylic oligomer (an oligomer is a short polymer chain) is an
acrylated molecule, which can include, but is not limited to,
polyesters of acrylic acid and methacrylic acid and a polyhydric
alcohol (e.g., polyacrylates and polymethacylates of
trimethylolpropane, pentaerythritol, ethylene glycol, propylene
glycol). In addition, the acrylic oligomer can be a
urethane-acrylate.
[0039] An acrylic crosslinker is a polyfunctional molecule, which
provides enhanced crosslinking. Examples of acrylic crosslinkers
includes, but is not limited to, 1,4-butanediol diacrylate,
1,4-butanediol dimethacrylate, 1,6-hexamethylene glycol diacrylate,
neopentyl glycol dimethacrylate, trimethylol propane
trimethacrylate, pentaerythritol triacrylate, penta-erythritol
trimethacrylate triethylene glycol triacrylate, triethylene glycol
trimethacrylate, urethane acrylate, trimethylol propane
triacrylate, and urethane methacrylates.
[0040] The build material can also be a chemical having one or more
vinyl ether substituents such as, but not limited to, vinyl ether
monomers and oligomers having at least one vinyl ether group.
Exemplary vinyl ethers include, but are not limited to, ethyl vinyl
ether, propyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl
ether, 2-ethylhexyl vinyl ether, butyl vinyl ether, ethyleneglycol
monovinyl ether, diethyleneglycol divinyl ether, butane diol
divinyl ether, hexane diol divinyl ether, cyclohexane dimethanol
monovinyl ether, and 1,4 cyclohexane dimethanol divinyl.
[0041] The build material can also include chemicals having one or
more epoxy substituents such as, but not limited to, epoxy monomers
and oligomers having at least one oxirane moiety. Examples of
epoxy-containing build materials include, but are not limited to,
bis-(3,4 cyclohexylmethyl carboxylate), 3,4-epoxy cyclohexylmethyl
carboxylate, 3,4-epoxycydohexyl carboxylate , diglycidyl ether
vinylcyclohexene, 1,2 epoxy-4-vinylcyclohexane carboxylate,
2,4-epoxycyclohexylmethyl carboxylate, 3,4-epoxy cyclohexane
carboxylate, and the like.
[0042] Preferably, the build material includes chemicals such as,
but not limited to, acrylates and derivatives thereof, epoxy
acrylates and derivatives thereof, urethane acrylates and
derivatives thereof, and combinations thereof. In addition, the
build material can include materials, which otherwise may be
excluded from solid freeform fabrication processes using ink-jet
technologies because of high viscosity at room temperature. These
build materials can include, but are not limited to, ethoxylated
acrylates, methacrylates (e.g., ethoxylated nonyl phenol acrylate,
which has a viscosity of about 100 cps at 25.degree. C. (Sartomer
Inc., SR504), ethoxylated nonyl phenol ethacrylate, which has a
viscosity of about 80 cps at 25.degree. C. (Sartomer Inc., CD612),
ethoxylated bisphenol dimethacrylate, which has a viscosity of
about 400 cps at 25.degree. C. (Sartomer Inc., SR480)),
caprolactone acrylate, which has a viscosity of about 80 cps at
25.degree. C. (Sartomer Inc., SR495), and the like.
[0043] In addition, the build material can include high viscosity
materials such as, but not limited to, monomers and oligomers such
as: ethoxylated bisphenol-A dimethacrylate compounds (e.g.,
Sartomer Inc., SR348 (1082 cps at 25.degree. C.), Sartomer Inc.,
SR9036 (610 cps at 25.degree. C.), Sartomer Inc., CD541 (440 cps at
25.degree. C.), Sartomer Inc., SR480 (410 cps at 25.degree. C.),
and Sartomer Inc., CD540 (555 cps at 25.degree. C.)), ethoxylated
bisphenol-A diacrylates compounds (e.g., Sartomer Inc., SR601 (1080
cps at 25.degree. C.), Sartomer Inc., SR602 (610 cps at 25.degree.
C.), CD9038 (680 cps at 25.degree. C.), and Sartomer Inc., SR349
(1600 cps at 25.degree. C.)), pentaerythrol triacrylate compounds
(e.g., Sartomer Inc., SR344 (520 cps at 25.degree. C.)), and
ethoxylated trimethylolpropane triacrylate compounds (e.g.,
Sartomer Inc., SR415 (225-520 cps at 25.degree. C.)).
[0044] It should be noted that viscosity, temperature, ratios,
concentrations, amounts, and other numerical data may be expressed
herein in a range format. It is to be understood that such a range
format is used for convenience and brevity, and thus, should be
interpreted in a flexible manner to include not only the numerical
values explicitly recited as the limits of the range, but also to
include all the individual numerical values or sub-ranges
encompassed within that range as if each numerical value and
sub-range is explicitly recited. To illustrate, a concentration
range of "about 0.1% to about 5%" should be interpreted to include
not only the explicitly recited concentration of about 0.1 wt % to
about 5 wt %, but also include individual concentrations (e.g., 1%,
2%, 3%, and 4%) and the sub-ranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%,
and 4.4%) within the indicated range.
[0045] The visible radiation initiator can include, but is not
limited to, .quadrature.-diketones (e.g., camphorquinone,
1,2-acenaphthylenedione, 1H-indole-2,3-dione,
5H-dibenzo[a,d]cycloheptene-10,and 11-dione), phenoxazine dyes
(e.g., Resazurin, Resorufin), acylphosphine oxides, (e.g.,
diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide), and the
like.
[0046] Many variations and modifications may be made to the
above-described embodiments. All such modifications and variations
are intended to be included herein within the scope of this
disclosure and protected by the following claims.
* * * * *