U.S. patent application number 15/252182 was filed with the patent office on 2018-03-01 for photopolymer composition for 3d printing.
The applicant listed for this patent is Nano and Advanced Materials Institute Limited. Invention is credited to Wai Yan CHAN, Ka Leung Kevin CHEUK, Jifan LI, Ka Kit YEE.
Application Number | 20180057691 15/252182 |
Document ID | / |
Family ID | 61226096 |
Filed Date | 2018-03-01 |
United States Patent
Application |
20180057691 |
Kind Code |
A1 |
LI; Jifan ; et al. |
March 1, 2018 |
Photopolymer composition for 3D printing
Abstract
The present invention provides photopolymer compositions for 3D
printing which have low viscosity, proper curing rate, low volume
shrinkage, and low ash content. Such compositions may be used in 3D
printing for direct investment casting of products and rapid
prototyping.
Inventors: |
LI; Jifan; (Hong Kong,
CN) ; CHAN; Wai Yan; (Hong Kong, CN) ; YEE; Ka
Kit; (Hong Kong, CN) ; CHEUK; Ka Leung Kevin;
(Hong Kong, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nano and Advanced Materials Institute Limited |
Hong Kong |
|
CN |
|
|
Family ID: |
61226096 |
Appl. No.: |
15/252182 |
Filed: |
August 30, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09D 11/03 20130101;
C08F 222/1035 20200201; C09D 4/00 20130101; C09D 11/101 20130101;
C09D 4/00 20130101; C08F 222/10 20130101; C08F 222/1035 20200201;
C08F 220/20 20130101; C08F 220/1818 20200201; C08F 222/1035
20200201; C08F 220/1818 20200201; C08F 220/20 20130101 |
International
Class: |
C09D 4/00 20060101
C09D004/00; C09D 11/101 20060101 C09D011/101 |
Claims
1.-13. (canceled)
14. A photopolymer composition that produces 3D printed objects,
the photopolymer composition comprising: at least one
polyfunctional (meth)acrylate monomer; at least one space-filling
monomer or organic compounds; at least one (meth)acrylate monomer;
at least one photo-initiator; and at least one light stabilizer,
wherein the at least one light stabilizer controls a cure depth of
the 3D printed objects having a low ash content, prevents
photodegradation, and is selected from a group consisting of Sudan
dyes,
2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzortriazole,
2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzortriazole,
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole) and
(2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene.
15. The photopolymer composition of claim 14, wherein the
polyfunctional (meth)acrylate monomer is UV/visible curable, and is
selected from a group consisting of ethylene glycol dimethacrylate,
diethylene glycol dimethacrylate, 1,6-hexanediol dimethacyrlate,
trimethyolpropane trimethacrylate, trimethyolpropane triacrylate,
ethoxylated trimethylol propane trimethacrylate, ethyoxylated
pentaerythritol tetramethacrylate, pentaerythritol
tetramethacrylate, ethoxylated trimethylolpropane triacrylate, and
pentaerythritol tetraacrylate.
16. The photopolymer composition of claim 14, wherein the
space-filling monomer or organic compounds has low melting point
and comprises one functional group selected from a group consisting
of polyoxyethylene (40) stearate, 1-hexadecanol, 1-pentadecanol,
1-octadecanol, 1-tetradecanol, bisphenol A glycerolate
dimethacrylate, stearyl methacrylate and octadecyl acrylate.
17. The photopolymer composition of claim 14, wherein the
(meth)acrylate monomer serves to adjust viscosity and increase the
solubility of space-filling monomer, and is selected from a group
consisting of isobornyl acrylate, 2-hydroxyethyl acrylate,
4-hydroxybutyl acrylate, 2-hydroxybutyl acrylate, and
2-hydroxyethyl methacrylate.
18. The photopolymer composition of claim 14, wherein the photo
initiator generates radicals by UV/Visible light to initiate
polymerization, and is selected from a group consisting of
bis(2,4,6-trimethyl benzoyl)phenyl phosphine oxide and
2,4,6-trimethylbenzoyl diphenyl phosphine oxide.
19. (canceled)
20. The photopolymer composition of claim 14, wherein the
photopolymer composition comprises 10-40 wt % polyfunctional
(meth)acrylate monomer, 30-50 wt % space-filling monomer or organic
compounds, 15-35 wt % (methy)acrylate monomer, 0.5-5 wt %
photo-initiator, and 0.01-1 wt % light stabilizer.
21. The photopolymer composition of claim 20, wherein the
photopolymer composition comprises 36.29 wt % pentaerythritol
tetramethacrylate, 30.92 wt % stearyl methacrylate, 30.92 wt %
2-hydroxybutyl acrylate, 1.84 wt % 2,4,6-trimethylbenzoyl diphenyl
phosphine, and 0.03 wt % Sudan I dye.
22. The photopolymer composition of claim 14, wherein the
photopolymer composition comprises 20-40 wt % polyfunctional
(meth)acrylate monomer, 20-40 wt % space-filling monomer or organic
compounds, 20-40 wt % (methy)acrylate monomer, 0.5-5 wt %
photo-initiator, and 0.01-1 wt % light stabilizer.
23. The photopolymer composition of claim 22, wherein the
photopolymer composition comprises 33.09 wt % trimethyolpropane
trimethacrylate, 33.09 wt % stearyl methacrylate, 33.09 wt %
isobornyl acrylate, 0.57 wt % 2,4,6-trimethylbenzoyl diphenyl
phosphine, and 0.16 wt %
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole).
24. A photopolymer composition that produces 3D printed objects,
the photopolymer composition comprising: at least one
polyfunctional (meth)acrylate monomer; at least one space-filling
monomer or organic compounds; at least one (meth)acrylate monomer;
at least one photo-initiator; and at least one light stabilizer
that is selected from a group consisting of Sudan dyes,
2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzortriazole,
2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzortriazole,
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole) and
(2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene.
25. The photopolymer composition of claim 24, wherein the
polyfunctional (meth)acrylate monomer is pentaerythritol
tetramethacrylate; the space-filling monomer or organic compound is
stearyl methacrylate; the (meth)acrylate monomer is 2-hydroxybutyl
acrylate; the photo-initiator is 2,4,6-trimethylbenzoyl diphenyl
phosphine; and the light stabilizer is Sudan I dye.
26. The photopolymer composition of claim 25, wherein the
photopolymer composition comprises 36.29 wt % pentaerythritol
tetramethacrylate, 30.92 wt % stearyl methacrylate, 30.92 wt %
2-hydroxybutyl acrylate, 1.84 wt % 2,4,6-trimethylbenzoyl diphenyl
phosphine, and 0.03 wt % Sudan I dye.
27. The photopolymer composition of claim 24, wherein the
polyfunctional (meth)acrylate monomer is trimethyolpropane
trimethacrylate; the space-filling monomer or organic compound is
stearyl methacrylate; the (meth)acrylate monomer is isobornyl
acrylate; the photo-initiator is 2,4,6-trimethylbenzoyl diphenyl
phosphine; and the light stabilizer is
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole).
28. The photopolymer composition of claim 27, wherein the
photopolymer composition comprises 33.09 wt % trimethyolpropane
trimethacrylate, 33.09 wt % stearyl methacrylate, 33.09 wt %
isobornyl acrylate, 0.57 wt % 2,4,6-trimethylbenzoyl diphenyl
phosphine, and 0.16 wt %
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole).
29. A photopolymer composition that produces 3D printed objects,
the photopolymer composition comprising: at least one
polyfunctional (meth)acrylate monomer; at least one space-filling
monomer or organic compounds; at least one (meth)acrylate monomer;
at least one photo-initiator; and at least one light stabilizer,
wherein the photopolymer composition produces the 3D printed
objects that have a low ash content with an ash content at
600.degree. C. of less than 0.1%.
30. The photopolymer composition of claim 29, wherein the
polyfunctional (meth)acrylate monomer is pentaerythritol
tetramethacrylate; the space-filling monomer or organic compound is
stearyl methacrylate; the (meth)acrylate monomer is 2-hydroxybutyl
acrylate; the photo-initiator is 2,4,6-trimethylbenzoyl diphenyl
phosphine; and the light stabilizer is Sudan I dye.
31. The photopolymer composition of claim 30, wherein the
photopolymer composition comprises 36.29 wt % pentaerythritol
tetramethacrylate, 30.92 wt % stearyl methacrylate, 30.92 wt %
2-hydroxybutyl acrylate, 1.84 wt % 2,4,6-trimethylbenzoyl diphenyl
phosphine, and 0.03 wt % Sudan I dye.
32. The photopolymer composition of claim 29, wherein the
polyfunctional (meth)acrylate monomer is trimethyolpropane
trimethacrylate; the space-filling monomer or organic compound is
stearyl methacrylate; the (meth)acrylate monomer is isobornyl
acrylate; the photo-initiator is 2,4,6-trimethylbenzoyl diphenyl
phosphine; and the light stabilizer is
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole).
33. The photopolymer composition of claim 32, wherein the
photopolymer composition comprises 33.09 wt % trimethyolpropane
trimethacrylate, 33.09 wt % stearyl methacrylate, 33.09 wt %
isobornyl acrylate, 0.57 wt % 2,4,6-trimethylbenzoyl diphenyl
phosphine, and 0.16 wt %
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole).
Description
FIELD OF THE INVENTION
[0001] The present invention relates to photopolymer compositions
used for three-dimensional (3D) printing.
BACKGROUND
[0002] 3D printing is an additive manufacturing process, as opposed
to a subtractive manufacturing process which involves milling or
cutting of pieces in order to build a designed shape. In 3D
printing process, a material is added in successive layers until it
forms a shape of a desired product.
[0003] In 3D printing, hundreds or thousands of layers of material
are "printed" layer upon layer using various materials, most of
which are commonly plastic polymers or metals. Generally, the
printing technologies are material dependent. For instance,
photopolymer liquids are used in jetted 3D printer, acrylonitrile
butadiene styrene (ABS) material is used in fusion deposition
modeling (FDM) printer, and metals are used in laser sintering.
[0004] Among these 3D printing technologies, light polymerized
technologies, such as stereolithography (SLA) and digital light
processing (DLP) have incomparable advantages over FDM, such as
higher resolution, better mechanical strength, and smoother
surface.
[0005] In view of the demand for SLA/DLP technologies, polymer
compositions with improved performance are desired.
SUMMARY OF THE INVENTION
[0006] One example embodiment is a photopolymer composition for 3D
printing, comprising: at least one epoxy monomer; at least one
polyfunctional (meth)acrylate monomer; at least one space-filling
monomer; at least one a photo-initiator; at least one cationic
initiator; at least one co-initiator; and at least one light
stabilizer.
[0007] In a further example embodiment, the epoxy monomer is
selected from a group consisting of
3,4-epoxycyclohexanecarboxylate, bisphenol A diglycidyl ether,
trimethylolpropane triglycidyl ether, and pentaerythritol glycidyl
ether.
[0008] In another further example embodiment, the polyfunctional
(meth)acrylate monomer is UV/visible curable, and selected from a
group consisting of ethylene glycol dimethacrylate, diethylene
glycol dimethacrylate, 1,6-hexanediol dimethacyrlate,
trimethyolpropane trimethacrylate, trimethyolpropane triacrylate,
ethoxylated trimethyol propane trimethacrylate, ethyoxylated
pentaerythritol tetramethacrylate, ethoxylated trimethylolpropane
triacrylate, and pentaerythritol tetraacrylate.
[0009] In a further example, the space-filling monomer is
space-filling (meth)acrylate monomer and comprises at least one
rigid, bulky functional group which is selected from a group
consisting of bisphenol-A moiety, isobornyl moiety, cyclohexyl
moiety and phenyl moiety. In one embodiment, the space-filling
monomer is selected from a group consisting of 2,2
bis[4-(methacryloxy ethoxy)phenyl]propane, isobornyl methacrylate,
isobornyl acrylate, 2-phenoxyethylacrylate, and
3,3,5-trimethylcyclohexyl methacrylate.
[0010] In a further example embodiment, the cationic initiator
generates the cation radicals to initiate ring-opening
polymerization, and is selected from a group consisting of
bis(4-t-butylphenyl)iodonium hexafluorophosphate, and
bis(4-methylphenyl)iodonium hexafluorophosphate.
[0011] In a further example embodiment, the photo-initiator
generates free radicals by UV/Visible light to initiate
polymerization, and is selected from a group consisting of
bis(2,4,6-trimethyl benzoyl)phenyl phosphine oxide and
2,4,6-trimethylbenzoyl diphenyl phosphine.
[0012] In a further example embodiment, the co-initiator is
N-vinylcarbazole which accelerates the ring-opening
polymerization.
[0013] In a further example embodiment, the light stabilizer is
used to control cure depth in 3D printed products and prevent
photodegradation, and is selected from a group consisting of Sudan
dyes, 2-(2'-3',5'-di-tert-butylphenyl)-5-chlorobenzortriazole,
2-(2'-Hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzortriazole,
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole) and
(2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene.
[0014] In one example embodiment, the photopolymer composition
comprises 30-50 wt % epoxy monomer, 5-25 wt % polyfunctional
(meth)acrylate monomer, 30-50 wt % space-filling monomer, 0.5-2 wt
% photo-initiator, 0.5-2 wt % cationic initiator, 0.5-2 wt %
co-initiator, and 0.01-2 wt % light stabilizer. In a further
example, the photopolymer composition comprises 40.84 wt %
pentaerythritol glycidyl ether, 14.90 wt % trimethyolpropane
trimethacrylate, 40.84 wt % 2-phenoxyethylacrylate, 0.74 wt %
2,4,6-trimethylbenzoyl diphenyl phosphine, 0.88 wt %
bis(4-methylphenyl)iodonium hexafluorophosphate, 1.33 wt %
N-vinylcarbazole, and 0.47 wt % Sudan I dye.
[0015] In one example embodiment, the photopolymer composition
comprises 75-95 wt % epoxy monomer, 0.1-15 wt % polyfunctional
(meth)acrylate monomer, 0.1-10 wt % space-filling monomer, 0.5-2 wt
% photo-initiator, 0.5-2 wt % cationic initiator, 1-5 wt %
co-initiator, and 0.01-2 wt % light stabilizer. In a further
example, the photopolymer composition comprises 91.90 wt %
pentaerythritol glycidyl ether, 1.00 wt % trimethyolpropane
trimethacrylate, 1.00 wt % 2-phenoxyethylacrylate, 0.99 wt %
2,4,6-trimethylbenzoyl diphenyl phosphine, 1.98 wt %
bis(4-methylphenyl)iodonium hexafluorophosphate, 3.10 wt %
N-vinylcarbazole, and 0.03 wt % Sudan I dye.
[0016] Another example embodiment is a photopolymer composition for
3D printing comprising: at least one polyfunctional (meth)acrylate
monomer; at least one space-filling monomer or organic compounds;
at least one (meth)acrylate monomer; at least one photo-initiator;
and at least one light stabilizer.
[0017] In a further example embodiment, the polyfunctional
(meth)acrylate monomer is UV/visible curable, and is selected from
a group consisting of ethylene glycol dimethacrylate, diethylene
glycol dimethacrylate, 1,6-hexanediol dimethacyrlate,
trimethyolpropane trimethacrylate, trimethyolpropane triacrylate,
ethoxylated trimethyol propane trimethacrylate, ethyoxylated
pentaerythritol tetramethacrylate, pentaerythritol
tetramethacrylate, ethoxylated tri methylolpropane triacrylate, and
pentaerythritol tetraacrylate.
[0018] In a further example embodiment, the space-filling monomer
or organic compounds has low melting point and comprises one
functional group selected from a group consisting of
polyoxyethylene (40) stearate, 1-hexadecanol, 1-pentadecanol,
1-octadecanol, 1-tetradecanol, bisphenol A glycerolate
dimethacrylate, stearyl methacrylate and octadecyl acrylate.
[0019] In a further example embodiment, the (meth)acrylate monomer
serves to adjust viscosity and increase the solubility of
space-filling monomer, and is selected from a group consisting of
isobornyl acrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl
acrylate, 2-hydroxybutyl acrylate, and 2-hydroxyethyl
methacrylate.
[0020] In a further example embodiment, the photo-initiator
generates radicals by UV/Visible light to initiate polymerization,
and is selected from a group consisting of bis(2,4,6-trimethyl
benzoyl)phenyl phosphine oxide (BAPO) and 2,4,6-trimethylbenzoyl
diphenyl phosphine (TPO).
[0021] In a further example embodiment, the light stabilizer is
used to control cure depth of 3D printed products and prevent
photodegradation, and is selected from a group consisting of Sudan
dyes,
2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole,
2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzortriazole,
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole) and
(2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene.
[0022] In one example embodiment, the photopolymer composition
comprises 10-40 wt % polyfunctional (meth)acrylate monomer, 30-50
wt % space-filling monomer or organic compounds, 15-35 wt %
(methy)acrylate monomer, 0.5-5 wt % photo-initiator, and 0.01-1 wt
% light stabilizer. In a further example, the photopolymer
composition comprises 36.29 wt % pentaerythritol tetramethacrylate,
30.92 wt % stearyl methacrylate, 30.92 wt % 2-hydroxybutyl
acrylate, 1.84 wt % 2,4,6-trimethylbenzoyl diphenyl phosphine, and
0.03 wt % Sudan I dye.
[0023] In one example embodiment, the photopolymer composition
comprises 20-40 wt % polyfunctional (meth)acrylate monomer, 20-40
wt % space-filling monomer or organic compounds, 20-40 wt %
(methy)acrylate monomer, 0.5-5 wt % photo-initiator, and 0.01-1 wt
% light stabilizer. In a further example, the photopolymer
composition comprises 33.09 wt % trimethyolpropane trimethacrylate,
33.09 wt % stearyl methacrylate, 33.09 wt % isobornyl acrylate,
0.57 wt % 2,4,6-trimethylbenzoyl diphenyl phosphine, and 0.16 wt %
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole).
DETAILED DESCRIPTION
[0024] In particular, the present invention relates to photopolymer
compositions which have low viscosity, proper curing rate, low
volume shrinkage, and low ash content. Such compositions may be
used in 3D printing for direct investment casting of products and
rapid prototyping.
[0025] The photopolymer used in SLA/DLP process is the key to the
successes of the printed prototype. However, the current
photopolymer suffers problems like shrinkage occurring upon
solidification which results in warpage or curling phenomena. In
addition, the thermal-mechanical properties thereof are poor during
burnout cycles. The amount of ash is higher than expected at
relatively lower burnout temperature. The incomplete burnout
process causes residual ash to remain in the mold and leads to poor
surface properties.
[0026] Therefore, there is a need to provide an advanced
photopolymer composition which offers improved burn out properties
with a minimal amount of ash residue for investment casting.
[0027] The volume shrinkage is also one of the well-known
deficiencies of photopolymerization materials. When the inherent
polymerization shrinkage strain is frustrated by sufficient
interfacial adhesion between the polymer and base substrate, stress
is conveyed to the substrate. If the stress exceeds the adhesive
strength of any component of the system, the micro- or macro-defect
can emerge. The bulk volume shrinkage in photopolymerization is an
unavoidable result of the formation of new covalent bonds via the
van der Waals force.
[0028] Although numerous of methods have been reported to reduce
the polymerization volume shrinkage, there remains a need to
develop an advanced photopolymer composition that has lower volume
shrinkage rate.
[0029] Researches have been carried out to reduce the
polymerization volume shrinkage, which could be divided into three
types: changing the monomer structure or chemical structure, adding
fillers or additives, and changing process conditions. The chemical
method is a convenient way to reduce the shrinkage rate. It is
proved that free radical/cationic hybrid system, such as
(meth)acrylate/epoxy, is efficient to decrease the volume shrinkage
due to the two polymer network formation, especial for those
flexible structure containing system.
[0030] The other way to reduce shrinkage rate of composite resin is
changing the monomer structure. By introducing space-filling
monomer to the composite resin, the volume shrinkage can be
minimized. Bisphenol A-glycidyl methacrylate (Bis-GMA) is an
especially important monomer in 3D printing industry because of its
unique properties such as low-shrink and high stiffness. However,
the high viscosity of Bis-GMA resulted in slow polymerization rate
and further limited its applications. It is therefore typically
diluted with a less viscous acrylate or methacrylate monomer, such
as TEGDMA, or tetraethylene glycol dimethacrylate. However, such
low molecular weight monomers contribute to increased shrinkage.
Bulky acrylate monomers such as isobornyl acrylate (IBOA) and
isobornyl methacrylate (IBOMA) are two acrylate monomers with low
viscosity and shrinkage values. IBOA and IBOMA were used as
diluents to replace in the Bis-GMA/TEGDMA system because of their
low polymerization shrinkage.
[0031] An example embodiment includes a high performance
photopolymer for 3D printing. These developed photopolymer have low
volume shrinkage, and low burnout ash content. A hybrid network
based on acrylate, epoxy was developed using free radical/cationic
hybrid system in order to reduce the volume shrinkage.
Space-filling monomers are introduced into the photopolymer
composites in order to reduce the volume shrinkage. To minimize the
burnout ash content, low melting point space-filling monomer was
added into the composition.
[0032] High Performance Photopolymer with Low Volume Shrinkage
[0033] One object of an example embodiment relates to photo-curable
polymer compositions used to produce low volume shrinkage
3D-printed product. By "low shrinking" it means a material having
volume shrinkage of less than about 5%. In one example embodiment,
a low volume shrinkage photopolymer composition is prepared from a
photo-curable mixture that includes (i) at least one UV/visible
curable polyfunctional (meth)acrylate monomer; (ii) at least one
epoxy monomer; (iii) at least one space-filling (meth)acrylate
monomer; (iv) at least one photo-initiator; (v) at least one
cationic initiator; (vi) at least one co-initiator, and (vii) at
least one light stabilizer.
[0034] In one example embodiment, a photo-curable liquid low volume
shrinkage photopolymer composition includes any type of
polyfunctional (meth)acrylates monomer having two or more
functionalities. The polyfunctional monomer serves to enhance the
curing rate, adjust viscosity, and improve toughness of the
3D-printed product.
[0035] In one example embodiment, a photo-curable liquid low volume
shrinkage photopolymer composition includes any type of epoxy
monomer. The polymerization of epoxy monomer serves to reduce the
volume shrinkage of the 3D-printed product due to the ring opening
volume expansion.
[0036] In one example embodiment, a photo-curable liquid low volume
shrinkage photopolymer composition includes space-filling
(meth)acrylate monomer having space-filling bulky functional
group(s) to provide low volume shrinkage composition. The
space-filling monomer of an example embodiment is a monomer that
contains a rigid, bulky functional group that can miscible into
composites, which exhibit low volumetric shrinkage during
polymerization.
[0037] In one example embodiment, a photo-curable liquid low volume
shrinkage photopolymer composition includes a photo-initiator which
functions to generate radicals by UV/Visible light to initiate
polymerization.
[0038] In one example embodiment, a photo-curable liquid low volume
shrinkage photopolymer composition includes a co-initiator which
functions to accelerate the ring-opening polymerization.
Representative example of co-initiator is N-vinylcarbazole. This
compound can undergo addition process to hardly oxidizable
radicals. The resultant radicals can be easily oxidized by a
cationic initiator and thereby accelerating the ring opening
polymerization of epoxides.
[0039] In one example embodiment, a photo-curable liquid low volume
shrinkage photopolymer composition includes a cationic initiator
which functions to generate cation by radical to initiate
ring-opening polymerization.
[0040] In one example embodiment, a photo-curable liquid low volume
shrinkage photopolymer composition includes one or more light
absorber. The functions of light absorbers include control of cure
depth in an attempt to improve accuracy of 3D-printed parts and
prevent photodegradation.
[0041] High Performance Photopolymer with Low Ash Content
[0042] Another object of an example embodiment is to provide
photo-curable compositions used to produce low ash 3D-printed
object. By "low ash" it is meant a material having ash content at
600.degree. C. of less than 0.1%. In one example embodiment, a low
ash photopolymer composition is prepared from a photo-curable
viscous mixture that includes (i) at least one UV/visible curable
polyfunctional (meth)acrylate monomer; (ii) at least one
space-filling monomer or organic compounds; (iii) at least one
(meth)acrylate monomer; (iv) at least one photo-initiator; and (v)
at least one light stabilizer.
[0043] In one example embodiment, a photo-curable liquid low ash
photopolymer composition includes any type of polyfunctional
(meth)acrylates monomer having two or more functionalities used for
preparation of a 3D-printed products. The polyfunctional monomer
serves to enhance the curing rate, adjust viscosity, and improve
toughness of the 3D-printed product.
[0044] In one example embodiment, a photo-curable liquid low ash
photopolymer composition includes space-filling monomer or organic
compounds. The space-filling monomer is a low melting point organic
compound that can be fully dissolved in the monomer solution.
During the burn out cycle, the space-filling monomer melts away
first allowing the polymer to burn off without excessive expansion
or pressure from degassing which is a problem normally associated
with polymer based materials during the burn out cycle.
[0045] In one example embodiment, a photo-curable liquid low ash
photopolymer composition includes (meth)acrylate monomer serve to
adjust viscosity and increase the solubility of space-filling
monomer.
[0046] In one example embodiment, a photo-curable liquid low ash
photopolymer composition includes a photo-initiator which functions
to generate radicals by UV/Visible light to initiate
polymerization.
[0047] In one example embodiment, a photo-curable liquid low ash
photopolymer composition includes one or more light absorber. The
functions of light absorbers include control of cure depth in an
attempt to improve accuracy of 3D-printed product and prevent
photodegradation.
EXAMPLE 1
[0048] A masterbatch composition containing 30-50 wt % epoxy
monomer, 5-25 wt % polyfunctional (meth)acrylate monomer, 30-50 wt
% space-filling monomer, 0.5-2 wt % photo-initiator, 0.5-2 wt %
cationic initiator, 0.5-2 wt % co-initiator, and 0.01-2 wt % light
stabilizer, was made up by mixing the components well under subdued
light. Specifically, a composition containing 40.84 wt %
pentaerythritol glycidyl ether, 14.90 wt % trimethyolpropane
trimethacrylate, 40.84 wt % 2-phenoxyethylacrylate, 0.74 wt %
2,4,6-trimethylbenzoyl diphenyl phosphine (TPO), 0.88 wt %
bis(4-methylphenyl)iodonium hexafluorophosphate, 1.33 wt %
N-vinylcarbazole, and 0.47 wt % Sudan I dye is prepared. The
photopolymer composition was cured using 3D-printer for testing.
The characterized properties of the cured photopolymer are shown in
Table 1.
TABLE-US-00001 TABLE 1 The properties of 3D photopolymer
composition. Properties Results Viscosity 70-80 cP Hardness 78 D
Density 1.078 g/mL Polymer density 1.132 g/mL Volume shrinkage
4.78%
EXAMPLE 2
[0049] A masterbatch composition containing 10-40 wt %
polyfunctional (meth)acrylate monomer, 30-50 wt % space-filling
monomer or organic compounds, 15-35 wt % (methy)acrylate monomer,
0.5-5 wt % photo-initiator, and 0.01-1 wt % light stabilizer, was
made up by mixing the components well under subdued light.
Specifically, a composition containing 36.29 wt % pentaerythritol
tetramethacrylate, 30.92 wt % stearyl methacrylate, 30.92 wt %
2-hydroxybutyl acrylate, 1.84 wt % 2,4,6-trimethylbenzoyl diphenyl
phosphine, and 0.03 wt % Sudan I dye is prepared. The photopolymer
composition was cured using 3D-printer for testing. The test
results are shown in Table 2.
TABLE-US-00002 TABLE 2 The properties of 3D photopolymer
composition. Properties Results Viscosity 70-80 cP Hardness 70 D
Density 1.091 g/mL Polymer density 1.193 g/mL Volume shrinkage
8.54% Ash content 0.098%
EXAMPLE 3
[0050] A masterbatch composition containing 20-40 wt %
polyfunctional (meth)acrylate monomer, 20-40 wt % space-filling
monomer or organic compounds, 20-40 wt % (methy)acrylate monomer,
0.5-5 wt % photo-initiator, and 0.01-1 wt % light stabilizer, was
made up by mixing the components well under subdued light.
Specifically, a composition containing 33.09 wt % trimethyolpropane
trimethacrylate, 33.09 wt % stearyl methacrylate, 33.09 wt %
isobornyl acrylate, 0.57 wt % 2,4,6-trimethylbenzoyl diphenyl
phosphine, and 0.16 wt %
2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole).The
photopolymer composition was cured using 3D-printer for testing.
The test results are shown in Table 3.
TABLE-US-00003 TABLE 3 The properties of 3D photopolymer
composition. Properties Results Viscosity 220 cP Hardness 90 D
Density 1.095 g/mL Polymer density 1.170 g/mL Volume shrinkage
6.42% Ash content 0.06%
EXAMPLE 4
[0051] A masterbatch composition containing 75-95 wt % epoxy
monomer, 0.1-15 wt % polyfunctional (meth)acrylate monomer, 0.1-10
wt % space-filling monomer, 0.5-2 wt % photo-initiator, 0.5-2 wt %
cationic initiator, 1-5 wt % co-initiator, and 0.01-2 wt % light
stabilizer, was made up by mixing the components well under subdued
light. Specifically, a composition containing 91.90 wt %
pentaerythritol glycidyl ether, 1.00 wt % trimethyolpropane
trimethacrylate, 1.00 wt % 2-phenoxyethylacrylate, 0.99 wt %
2,4,6-trimethylbenzoyl diphenyl phosphine, 1.98 wt %
bis(4-methylphenyl)iodonium hexafluorophosphate, 3.10 wt %
N-vinylcarbazole, and 0.03 wt % Sudan I dye. The photopolymer
composition was cured using 3D-printer for testing. The
characterized properties of the cured photopolymer are shown in
Table 4.
TABLE-US-00004 TABLE 4 The properties of 3D photopolymer
composition. Properties Results Hardness 65 D Density 1.147 g/mL
Polymer density 1.191 g/mL Volume shrinkage 3.74%
[0052] The exemplary embodiments of the present invention are thus
fully described. Although the description referred to particular
embodiments, it will be clear to one skilled in the art that the
present invention may be practiced with variation of these specific
details. Hence this invention should not be construed as limited to
the embodiments set forth herein.
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