U.S. patent application number 13/896877 was filed with the patent office on 2013-11-21 for adhesive for 3d printing.
This patent application is currently assigned to 3D Systems, Inc.. The applicant listed for this patent is 3D Systems, Inc.. Invention is credited to Martin Alan Johnson, Praveen Tummala, Peter Scott Turner.
Application Number | 20130310507 13/896877 |
Document ID | / |
Family ID | 48485536 |
Filed Date | 2013-11-21 |
United States Patent
Application |
20130310507 |
Kind Code |
A1 |
Tummala; Praveen ; et
al. |
November 21, 2013 |
Adhesive for 3D Printing
Abstract
In one aspect, adhesives for use with a 3D printer are described
herein. In some embodiments, an adhesive for use with a 3D printer
comprises a first polymeric component comprising a poly(vinyl
alcohol) and a second polymeric component. The poly(vinyl alcohol),
in some embodiments, comprises amorphous poly(vinyl alcohol). In
some embodiments, the second polymeric component comprises a
water-soluble polymer. Further, in some embodiments, an adhesive
described herein further comprises a solvent, a surfactant, and/or
a preservative.
Inventors: |
Tummala; Praveen; (Rock
Hill, SC) ; Turner; Peter Scott; (Valencia, CA)
; Johnson; Martin Alan; (Rock Hill, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3D Systems, Inc. |
Rock Hill |
SC |
US |
|
|
Assignee: |
3D Systems, Inc.
Rock Hill
SC
|
Family ID: |
48485536 |
Appl. No.: |
13/896877 |
Filed: |
May 17, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61649176 |
May 18, 2012 |
|
|
|
Current U.S.
Class: |
524/503 ;
525/56 |
Current CPC
Class: |
C09J 133/08 20130101;
C09J 129/10 20130101; C09J 179/00 20130101; C09J 129/04 20130101;
C08L 29/04 20130101; C08L 79/02 20130101; B29C 64/106 20170801;
B29C 64/118 20170801; B29K 2029/04 20130101; B29C 64/40 20170801;
B29K 2033/04 20130101; B29C 64/124 20170801; B29C 64/245 20170801;
C08G 73/0233 20130101; C09J 177/00 20130101; B33Y 10/00 20141201;
C09J 179/02 20130101; B29C 37/0003 20130101; C09J 129/04 20130101;
C08L 79/02 20130101; C09J 179/02 20130101; C08L 29/04 20130101 |
Class at
Publication: |
524/503 ;
525/56 |
International
Class: |
C09J 129/04 20060101
C09J129/04 |
Claims
1. An adhesive for use with a 3D printer comprising: a first
polymeric component comprising a poly(vinyl alcohol); and a second
polymeric component.
2. The adhesive of claim 1, wherein the poly(vinyl alcohol)
comprises amorphous poly(vinyl alcohol).
3. The adhesive of claim 1, wherein the second polymeric component
comprises a poly(2-ethyl-2-oxazoline).
4. The adhesive of claim 1, wherein the second polymeric component
comprises a water-soluble polymer.
5. The adhesive of claim 4, wherein the water-soluble polymer is
extrudable.
6. The adhesive of claim 1 further comprising a solvent.
7. The adhesive of claim 6, wherein the solvent comprises deionized
water.
8. The adhesive of claim 1 further comprising a surfactant.
9. The adhesive of claim 1 further comprising a preservative.
10. The adhesive of claim 1, wherein the poly(vinyl alcohol) is
present in the adhesive in an amount between about 5 and about 50
weight percent.
11. The adhesive of claim 1, wherein the second polymeric component
is present in the adhesive in an amount between about 5 and about
50 weight percent.
12. The adhesive of claim 6, wherein the solvent is present in the
adhesive in an amount between about 50 and about 95 weight
percent.
13. The adhesive of claim 8, wherein the surfactant is present in
the adhesive in an amount between about 0.01 and about 0.5 weight
percent.
14. The adhesive of claim 9, wherein the preservative is present in
an amount between about 0.01 and about 0.5 weight percent.
15. The adhesive of claim 1, wherein the adhesive has a bonding
strength that is at least about 10 times greater at 100.degree. C.
than at room temperature.
16. The adhesive of claim 1, wherein the adhesive has a glass
transition temperature below about 100.degree. C.
17. The adhesive of claim 1, wherein the adhesive has a bonding
strength that is at least about 10 times greater when dry at
23.degree. C. than when wet at 23.degree. C.
18. The adhesive of claim 1, wherein the adhesive is
water-soluble.
19. The adhesive of claim 1, wherein the adhesive is
biodegradable.
20. A method of printing a 3D article comprising: applying an
adhesive to a build surface of a print pad of a 3D printer, the
adhesive comprising: a first polymeric component comprising a
poly(vinyl alcohol); and a second polymeric component.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority pursuant to 35 U.S.C.
.sctn.119(e) to U.S. Provisional Patent Application Ser. No.
61/649,176, filed on May 18, 2012, which is hereby incorporated by
reference in its entirety.
FIELD
[0002] The present invention relates to adhesives and, in
particular, to adhesives for use with three dimensional (3D)
printing systems.
BACKGROUND
[0003] Additive and subtractive manufacturing technologies enable
computer designs, such as CAD files, to be made into three
dimensional (3D) objects. 3D printing, also known as additive
manufacturing, typically comprises depositing, curing, fusing, or
otherwise forming a material into sequential cross-sectional layers
of the 3D object. For example, fused deposition modeling
techniques, which are generally disclosed in U.S. Pat. No.
4,749,347 and U.S. Pat. No. 5,121,329, among others, include
melting a filament of build material or print material and
extruding the print material out of a dispenser that is moved in
the x-, y-, and z-axes relative to a print pad. The print material
is generally deposited in layers in the x- and y-axes to form
cross-sectional layers that are stacked along the z-axis to form
the 3D object.
[0004] Commercially available three dimensional printers, such as
the Cube.RTM. 3D Printer manufactured by 3D Systems of Rock Hill,
S.C., use a print material or ink that is jetted or extruded
through a print head as a liquid to form various printed parts. In
some instances, the print material is deposited onto a print pad
(or onto a "raft" of support material disposed on the print pad),
which can result in the formation of a bond between the extruded
print material and the surface of the print pad (or between the
surface of the raft and the surface of the print pad). However,
after the print process is complete, the bond is generally broken
and the printed part is removed from the print pad.
[0005] A weak bond between the extruded print material (or the
support material, if a raft is used) and the surface of the print
pad can cause the extruded print material to separate from the
print pad prematurely. Such separation can lead to a failed print
process and/or to imperfections in the printed 3D object. In
contrast, a strong bond can prevent the extruded print material
from separating from the print pad prematurely but may also make it
difficult to remove the printed 3D object and any support material
from the print pad following completion of the print process.
Further, this difficulty can require a user to employ a hand tool
such as a scraper to separate the printed 3D object from the print
pad, which can lead to damage to the printed 3D object and/or the
surface of the print pad.
[0006] In addition, because print pads are often reusable, it can
be desirable to remove all of the extruded print material or
support material of a previous print process prior to beginning a
new print process. In some instances, such removal can be tedious
and time consuming as well as damaging to the print pad. Therefore,
a need exists to improve the printing of 3D objects to provide
accurate parts, models, and other 3D objects that are easily and
safely removed from the print pad.
SUMMARY
[0007] The various embodiments of the present invention address the
above needs and achieve other advantages by providing an adhesive
that provides satisfactory bonding of the extruded print material
(or support material) to the print pad during the print process yet
enables the printed material to be easily separated from the print
pad after the print process. Such use of an adhesive in 3D printing
is not previously known. Thus, some embodiments of the present
invention may be used to allow printing of accurate 3D objects with
surfaces that are easily separated from both the print pad and from
the support structures in a manner not previously achieved. Some
embodiments of the present invention may be particularly
advantageous with 3D printing techniques that use the same print
material to print the 3D object and the support structure. However,
some embodiments of the present invention may also be used with 3D
printing techniques that use different materials to print the 3D
object and the support structure.
[0008] In one aspect, adhesives for use with a 3D printer are
described herein which, in some embodiments, may provide one or
more advantages compared to prior adhesives. For example, in some
embodiments, an adhesive described herein can provide a bond
between a print material (or a raft) and a print pad having a
desired adhesive strength. In addition, in some embodiments, an
adhesive described herein is operable to selectively bond or
release a print material to or from a print pad. In some
embodiments, for instance, the adhesive properties of an adhesive
described herein are temperature dependent. In some embodiments,
the adhesive properties are water-sensitive.
[0009] An adhesive for use with a 3D printer described herein, in
some embodiments, comprises a first polymeric component comprising
a poly(vinyl alcohol) and a second polymeric component. The first
polymeric component and the second component are not the same
material but are instead separate components of the adhesive. The
poly(vinyl alcohol), in some embodiments, comprises amorphous
poly(vinyl alcohol). In some embodiments, the second polymeric
component comprises a water-soluble polymer such as a
poly(2-ethyl-2-oxazoline). Further, in some embodiments, an
adhesive described herein further comprises a solvent, a
surfactant, and/or a preservative.
[0010] In another aspect, methods of printing a 3D article or
object are described herein. In some embodiments, a method of
printing a 3D article comprises applying an adhesive to a build
surface of a print pad of a 3D printer, the adhesive comprising a
first polymeric component comprising a poly(vinyl alcohol) and a
second polymeric component. The first polymeric component and the
second component are not the same material but are instead separate
components of the adhesive. The method further comprises
selectively depositing layers of a fluid ink or print material onto
the surface of the print pad to form the 3D article. In some
embodiments, the method further comprises removing the 3D article
from the print pad. Moreover, in some embodiments, removing the 3D
article from the print pad comprises altering the adhesive property
of the adhesive.
[0011] These and other embodiments are described in greater detail
in the detailed description which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 illustrates a side view of an experimental setup used
to measure the adhesive properties of an adhesive according to one
embodiment described herein.
[0013] FIG. 2 illustrates a perspective view of the experimental
setup of FIG. 1.
[0014] FIG. 3 illustrates a perspective view of an experimental
setup used to measure the adhesion or bonding strength of an
adhesive according to one embodiment described herein.
DETAILED DESCRIPTION
[0015] Embodiments described herein can be understood more readily
by reference to the following detailed description, examples, and
drawings. Elements, apparatus and methods described herein,
however, are not limited to the specific embodiments presented in
the detailed description, examples, and drawings. It should be
recognized that these embodiments are merely illustrative of the
principles of the present invention. Numerous modifications and
adaptations will be readily apparent to those of skill in the art
without departing from the spirit and scope of the invention.
[0016] In addition, all ranges disclosed herein are to be
understood to encompass any and all subranges subsumed therein. For
example, a stated range of "1.0 to 10.0" should be considered to
include any and all subranges beginning with a minimum value of 1.0
or more and ending with a maximum value of 10.0 or less, e.g., 1.0
to 5.3, or 4.7 to 10.0, or 3.6 to 7.9.
[0017] Further, when the phrase "up to" is used in connection with
an amount or quantity, it is to be understood that the amount is at
least a detectable amount or quantity. For example, a material
present in an amount "up to" a specified amount can be present from
a detectable amount and up to and including the specified
amount.
[0018] The terms "three dimensional printing system," "three
dimensional printer," "printing," and the like generally describe
various solid freeform fabrication techniques for making three
dimensional (3D) articles or objects by selective deposition,
jetting, fused deposition modeling, and other techniques now known
in the art or that may be known in the future that use a build
material or print material to fabricate the three dimensional
object.
[0019] As understood by one of ordinary skill in the art and as
described further herein, 3D printing can include selectively
depositing layers of a fluid build or print material to form a 3D
article on a substrate such as a print pad. Any print pad not
inconsistent with the objectives of the present invention may be
used. In some embodiments, for instance, a print pad comprises an
anodized aluminum print surface. In other embodiments, a print pad
comprises a glass print surface such as a clear soda lime float
glass surface or a polymeric print surface such as a polycarbonate
print surface. Further, a print pad described herein can have a
smooth surface or a textured surface. For example, in some
embodiments, a glass print pad described herein has a "Course
Grind" finish on the build surface of the print pad, where the
"build surface" comprises the surface of the print pad on which
building or printing occurs.
[0020] In general, a fluid print material can be deposited onto a
print pad through a dispenser, which may be a heated nozzle through
which a filament print material is fed to generally melt the
filament print material and dispense the print material from the
exit of the dispenser. Any print material not inconsistent with the
objectives of the present invention may be used. In some
embodiments, the print material comprises an organic composition
such as organic polymeric composition. For example, in some
embodiments, a print material comprises a polylactic acid (PLA) or
acrylonitrile butadiene styrene (ABS) polymer. Other polymers may
also be used as a print material.
[0021] Moreover, in some embodiments, production of a 3D object in
a 3D printing system also includes the use of a support material in
conjunction with the print material. The support material can be
used to support at least one layer of the print material and can be
used to form a variety of support structures, such as one or more
fine points or a "raft." A raft, in some embodiments, can be
essentially planar and can form a lower portion of a support
structure in contact with the print pad, such that the raft is
disposed between the print pad and the print material of the 3D
article. Like the print material, the support material can be
jetted through a print head or other dispenser as a liquid. In some
embodiments, the support material can consist of hydrophobic
chemical species solid at ambient temperatures and liquid at the
elevated jetting temperatures. However, unlike the print material,
the support material is subsequently removed to provide the
finished three-dimensional part. In some embodiments, the support
material comprises the same material or has the same chemical
composition as the print material. In other instances, the support
material has a different chemical composition than the print
material.
[0022] Additionally, the print material and/or support material, in
some embodiments, can be selectively deposited according to an
image of the 3D article, the image being in a computer readable
format.
I. Adhesives
[0023] In one aspect, adhesives for use with a 3D printer are
described herein. More specifically, adhesives for use with a print
pad of a 3D printer are described herein. An "adhesive," in some
embodiments, comprises a material that is operable to bond a print
material or a raft to a print pad, including one or more print
materials, rafts, and/or print pads described herein, such as PLA
or ABS print materials and metal, glass, or plastic print pads.
Moreover, in some embodiments, an adhesive is operable to
selectively bond or release a print material or raft to or from a
print pad. For example, in some embodiments, the adhesive
properties of an adhesive described herein are
temperature-dependent. In some embodiments, the adhesive properties
are water-sensitive. As described herein, an adhesive can be
applied to a print pad prior to beginning of a printing process.
Such application of an adhesive to a print pad of a 3D printer as
described herein has not previously been known in the art.
[0024] In some embodiments, an adhesive described herein comprises
a first polymeric component comprising a poly(vinyl alcohol)
(hereinafter "PVOH") and a second polymeric component. The first
polymeric component and the second component are not the same
material but are instead separate components of the adhesive. In
some embodiments, an adhesive further comprises one or more of a
solvent, a surfactant, and a preservative. Alternatively, in other
embodiments, the first polymeric component of an adhesive described
herein does not necessarily comprise a PVOH. Moreover, in some
embodiments wherein the first polymeric component does not
necessarily comprise a PVOH, the first polymeric component and the
second polymeric component are the same. In other embodiments, the
first polymeric component and the second polymeric component are
different and are separate components of the adhesive.
[0025] Turning now to components of adhesives, adhesives described
herein, in some embodiments, comprise a first polymeric component
comprising a PVOH. Any PVOH not inconsistent with the objectives of
the present invention may be used. In some embodiments, a PVOH
comprises amorphous PVOH, including highly amorphous PVOH. In some
embodiments, a PVOH comprises crystalline PVOH.
[0026] A PVOH can have any molecular weight or molar mass not
inconsistent with the objectives of the present invention. In some
embodiments, a PVOH has a weight average molecular weight or molar
mass between about 5,000 and about 50,000 g/mol. In some
embodiments, a PVOH has a weight average molecular weight between
about 5,000 and about 20,000, between about 5,000 and about 15,000,
or between about 10,000 and about 15,000.
[0027] In addition, a PVOH can be present in an adhesive described
herein in any amount not inconsistent with the objectives of the
present invention. In some embodiments, a PVOH is present in the
adhesive, in an amount between about 1 and about 50 weight percent,
between about 2 and about 50 weight percent, between about 3 and
about 50 weight percent, or between about 5 and about 50 weight
percent, based on the total weight of the adhesive. In some
embodiments, a PVOH is present in an amount between about 1 and
about 20 weight percent, between about 1 and about 10 weight
percent, between about 3 and about 20 weight percent, or between
about 3 and about 10 weight percent, based on the total weight of
the adhesive. In some embodiments, a PVOH is present in an amount
between about 20 and about 40 weight percent or between about 25
and about 35 weight percent, based on the total weight of the
adhesive.
[0028] In some embodiments, a first polymeric component of an
adhesive described herein does not necessarily comprise a PVOH. In
some embodiments wherein a first polymeric component does not
necessarily comprise a PVOH, the first polymeric component
comprises one or more of a methyl vinyl ether/maleic anhydride
co-polymer, a poly(2-oxazoline), poly(2-ethyl-2-oxazoline),
poly(2-ethyl-oxazoline), polyvinylpyrrolidone, polyvinyl acetate,
ethylene vinyl alcohol, ethylene vinyl acetate, polymethyl
acrylate, polylactic acid, a starch based polymer, a cellulose
based polymer, polycaprolactone, a polyhydroxyalkanoate such as
polyhydroxybutyrate and/or polyhydroxybutyrate co-hydroxyalkanoate,
polyimide, polyesteramide, an ahphatic copolyester, aromatic
copolyester, poly(vinyl alcohol), and mixtures or blends
thereof.
[0029] Adhesives described herein, in some embodiments, also
comprise a second polymeric component. Any second polymeric
component not inconsistent with the objectives of the present
invention may be used. In some embodiments, a second polymeric
component comprises a water-soluble polymer such as an ionic
polymer, a polar polymer, or a hydrophilic polymer. A water-soluble
polymer, for reference purposes herein, has a solubility in water
at 25.degree. C. of greater than 10 mass percent, greater than 30
mass percent, greater than 50 mass percent, or greater than 90 mass
percent, based on the mass of the polymer.
[0030] In some embodiments, a second polymeric component comprises
an extrudable polymer. An extrudable polymer, for reference
purposes herein, comprises a polymer that can be extruded by a
plastic extrusion process. In some embodiments, a second polymeric
component comprises a polymer that is both water-soluble and
extrudable.
[0031] In some embodiments, a second polymeric component comprises
one or more of a methyl vinyl ether/maleic anhydride co-polymer, a
poly(2-oxazoline), poly(2-ethyl-2-oxazoline),
poly(2-ethyl-oxazoline), polyvinylpyrrolidone, polyvinyl acetate,
ethylene vinyl alcohol, ethylene vinyl acetate, polymethyl
acrylate, polylactic acid, a starch based polymer, a cellulose
based polymer, polycaprolactone, a polyhydroxyalkanoate such as
polyhydroxybutyrate and/or polyhydroxybutyrate co-hydroxyalkanoate,
polyimide, polyesteramide, an aliphatic copolyester, aromatic
copolyester, poly(vinyl alcohol), and mixtures or blends thereof.
In some embodiments, a polymer of the second polymeric component
does not comprise PVOH. Moreover, in some embodiments wherein a
first polymeric component of an adhesive described herein does not
comprise PVOH, the second polymeric component also does not
comprise PVOH.
[0032] A second polymeric component described herein can have any
molecular weight or molar mass not inconsistent with the objectives
of the present invention. In some embodiments, a second polymeric
component has a weight average molecular weight or molar mass
between about 5,000 and about 500,000. In some embodiments, a
second polymeric component has a weight average molecular weight
between about 10,000 and about 100,000 or between about 20,000 and
about 70,000.
[0033] A second polymeric component can be present in an adhesive
described herein in any amount not inconsistent with the objectives
of the present invention. In some embodiments, a second polymeric
component is present in an adhesive in an amount between about 1
and about 50 weight percent, between about 2 and about 50 weight
percent, between about 3 and about 50 weight percent, or between
about 5 and about 50 weight percent, based on the total weight of
the adhesive. In some embodiments, a second polymeric component is
present is an amount between about 10 and about 20 weight percent
or between about 5 and about 15 weight percent, based on the total
weight of the adhesive. In some embodiments, a second polymeric
component is present is an amount between about 15 and about 50
weight percent or between about 30 and about 50 weight percent,
based on the total weight of the adhesive.
[0034] Further, in some embodiments, an adhesive described herein
comprises only one polymeric component. Such a single polymeric
component, in some embodiments, can comprise, consist, or consist
essentially of any of the polymeric species described herein for a
first or second polymeric component of an adhesive. For example, in
some embodiments, a single polymeric component comprises, consists,
or consists essentially of a methyl vinyl ether/maleic anhydride
co-polymer, a poly(2-oxazoline), poly(2-ethyl-2-oxazoline),
poly(2-ethyl-oxazoline), polyvinylpyrrolidone, polyvinyl acetate,
ethylene vinyl alcohol, ethylene vinyl acetate, polymethyl
acrylate, polylactic acid, a starch based polymer, a cellulose
based polymer, polycaprolactone, a polyhydroxyalkanoate such as
polyhydroxybutyrate and/or polyhydroxybutyrate co-hydroxyalkanoate,
polyimide, polyesteramide, an aliphatic copolyester, aromatic
copolyester, or PVOH.
[0035] Such a single polymeric component can be present in an
adhesive described herein in any amount not inconsistent with the
objectives of the present invention. In some embodiments, a single
polymeric component is present in an adhesive in an amount between
about 5 and about 80 weight percent or between about 5 and about 60
weight percent, based on the total weight of the adhesive. In some
embodiments, a single polymeric component is present is an amount
between about 20 and about 80 weight percent, between about 20 and
about 60 weight percent, or between about 40 and about 70 weight
percent, based on the total weight of the adhesive.
[0036] Adhesives described herein, in some embodiments, also
comprise a solvent. Any solvent not inconsistent with the
objectives of the present invention may be used. In some
embodiments, a solvent comprises water, including distilled water
or deionized (DI) water. In some embodiments, a solvent comprises
one or more of acetone, ethanol, methanol, ethylene glycol,
propylene glycol, triethylene glycol, glycerin, acetamide, dimethyl
acetamide, dimethyl sulfoxide, methyl ethyl ketone, methylene
chloride, and combinations or mixtures thereof.
[0037] A solvent can be present in an adhesive described herein in
any amount not inconsistent with the objectives of the present
invention. In some embodiments, a solvent is present in the
adhesive in an amount greater than about 50 weight percent, based
on the total weight of the adhesive. In some embodiments, a solvent
is present in an amount between about 50 and about 95 weight
percent, based on the total weight of the adhesive. In some
embodiments, a solvent is present in an amount between about 55 and
about 75 weight percent or between about 60 and about 70 weight
percent, based on the total weight of the adhesive.
[0038] Adhesives described herein, in some embodiments, further
comprise a surfactant. Any surfactant not inconsistent with the
objectives of the present invention may be used. In some
embodiments, for instance, a surfactant comprises a non-ionic
surfactant. In some embodiments, a surfactant comprises a polyol
such as a diol. In some embodiments, a surfactant comprises an
alkoxylated diol. In some embodiments, a surfactant comprises a
cationic, anionic, or zwitterionic surfactant. For example, in some
embodiments, a surfactant comprises a quaternary ammonium compound
or quaternary ammonium salt such as cetyltrimethylammonium bromide.
Other non-limiting examples of surfactants suitable for use in some
embodiments described herein include SURFYNOL and/or DYNOL
surfactants (both available from Air Products), including SURFYNOL
104, SURFYNOL 440, SURFYNOL 2502, and DYNOL 604.
[0039] A surfactant can have any molar mass or molecular weight not
inconsistent with the objectives of the present invention. In some
embodiments, a surfactant has a molecular weight between about 100
and about 10,000. In some embodiments, a surfactant has a molecular
weight between about 1000 and about 10,000 or between about 5000
and about 10,000. In some embodiments, a surfactant has a molecular
weight between about 100 and about 500 or between about 500 and
about 1000. In some embodiments, a surfactant has a weight average
molecular weight between about 100 and about 50,000.
[0040] A surfactant can be present in an adhesive described herein
in any amount not inconsistent with the objectives of the present
invention. In some embodiments, a surfactant is present in an
adhesive in an amount between about 0.01 and about 1 weight
percent, based on the total weight of the adhesive. In some
embodiments, a surfactant is present is an amount between about
0.01 and about 0.1 weight percent or between about 0.01 and about
0.05, based on the total weight of the adhesive.
[0041] Adhesives described herein, in some embodiments, further
comprise a preservative. Any preservative not inconsistent with the
objectives of the present invention may be used. In some
embodiments, for instance, a preservative comprises a biocide. In
some embodiments, a preservative comprises an inorganic
composition, including metals and/or metal salts. In some
embodiments, for example, a preservative comprises metallic copper,
zinc, or silver or a salt of copper, zinc, or silver. In some
embodiments, a preservative comprises an alkali or alkaline earth
metal or salt thereof. In some embodiments, a preservative
comprises a nitrate or a nitrite, including a nitrate or a nitrite
of an alkali or alkaline earth species. In some embodiments, a
preservative comprises an aqueous solution.
[0042] A preservative can be present in an adhesive described
herein in any amount not inconsistent with the objectives of the
present invention. In some embodiments, a preservative is present
in an adhesive in an amount between about 0.01 and about 1 weight
percent, based on the total weight of the adhesive. In some
embodiments, a preservative is present is an amount between about
0.01 and about 0.1 weight percent or between about 0.01 and about
0.05 weight percent, based on the total weight of the adhesive.
[0043] Adhesives described herein, in some embodiments, can exhibit
one or more desirable properties. In some embodiments, an adhesive
exhibits good adhesion to a print material, support material,
printed part and/or a print pad, including a print material,
support material, printed part, and/or a print pad described
herein. In some embodiments, an adhesive exhibits good adhesion to
both a print material/support material/printed part and a print pad
simultaneously, providing bonding of the print material/support
material/printed part to the print pad. Moreover, in some
embodiments, an adhesive described herein is capable of bonding or
adhering to a print pad such as an anodized aluminum print pad even
if the print pad has been worn or damaged. For example, in some
embodiments, an adhesive described herein can bond or adhere to a
print pad that has lost some or all of its anodized coating. In
some embodiments, an adhesive described herein can bond or adhere
to a glass print pad, including a textured glass print pad. In some
embodiments, an adhesive described herein can bond or adhere to a
polymer print pad such as a polycarbonate print pad. Further, in
some embodiments, an adhesive is capable of bonding or adhering to
a print material and/or print pad without the use of a raft.
[0044] Some improved adhesion properties of an adhesive according
to some embodiments described herein were demonstrated by a 180
degree peel adhesion test as follows. The surface used for the peel
adhesion test was an anodized aluminum print pad described herein
having a 150 mm.times.150 mm build surface. The tape used for the
peel adhesion test was a polyester tape equipped with silicone glue
(3M 8992 tape) and having a width of 100 mm and a thickness of 0.1
mm. FIGS. 1 and 2 illustrate the setup of the 180 degree peel
adhesion test. FIG. 1 illustrates a side view of the setup. FIG. 2
illustrates a perspective view of the setup. As illustrated in
FIGS. 1 and 2, the print pad (100) was fixed in the bottom fixture
(210) and the tape (300) was fixed in the top fixture (220) on a
MTS tensile tester (not shown) in tensile testing mode. The test
was performed by pulling the tape (300) at a speed of 0.5
inches/min. The maximum load required to peel the tape (300) from
the build surface of the print pad (100) was recorded.
[0045] In one embodiment comprising an anodized aluminum print pad,
the tape was first adhered to the bare surface of the print pad. In
this case, the maximum load required to peel the tape was measured
to be 8 Newton or 1.8 lb-f. Second, a single coat of an adhesive
described herein was applied to a 100 mm.times.100 mm area of the
print pad surface using an applicator with a sponge tip, providing
a coating thickness of 0.05-0.1 mm. Following application of the
adhesive, the adhesive was allowed to dry and then the tape was
adhered on top of the adhesive. The 180 degree peel test was then
performed again. In this case, the maximum load required to peel
the tape was measured to be 17 Newtons or 3.8 lb-f. In both cases,
the failure interface was the interface between the silicone glue
on the back of the tape and the bare print pad or the adhesive
applied to the print pad. This test demonstrated that an adhesive
described herein provides much better adhesion to a print material
than the bare print pad surface. Despite using a tape equipped with
a silicone glue, which is relatively inert, the adhesion of the
tape to the print pad almost doubled when an adhesive described
herein was used.
[0046] In addition, an adhesive described herein, in some
embodiments, has adhesive properties that are tunable or
selectable, so that the adhesive can act as both a bonding agent
and a releasing agent. A bonding agent, in some embodiments,
comprises a material that is operable to bond a print material or
printed part to a print pad. A releasing agent, in some
embodiments, comprises a material that facilitates release or
separation of a print material or printed part from a print pad. In
some embodiments, the adhesion or bonding strength of an adhesive
to a print material and/or print pad is tunable such that the
adhesive can serve as a bonding agent during the print process but
a release agent after the print process. For example, in some
embodiments, an adhesive described herein has an adhesion or
bonding strength that is temperature-dependent and/or
water-sensitive. In some embodiments, an adhesive has an adhesion
or bonding strength described in Table I hereinbelow. The adhesion
or bonding strengths of Table I refer to the force needed to
separate a pyramid-shaped printed part having a footprint of either
2 inches by 2 inches or 3 inches by 3 inches from the print pad at
the stated temperature, with or without a raft. The labels "Dry"
and "Wet" refer to whether or not the print pad and part were
submerged in water. For entries in Table I below having an adhesion
or bonding strength greater than 20 pounds, the parts broke before
the parts separated from the print pad. FIG. 3 illustrates an
experimental setup for the adhesion or bonding strength testing. As
illustrated in FIG. 3, a printed part (400) is adhered or bonded to
a print pad (100) using an adhesive described herein (not shown). A
force gauge (500) is used to measure the force applied by a user
(600) in direction (F) needed to separate the printed part (400)
from the print pad (100). As understood by one of ordinary skill in
the art, however, other experimental setups could also be used.
TABLE-US-00001 TABLE I 100.degree. C. 23.degree. C. 23.degree. C.
Footprint Raft Print Pad (Dry) (Dry) (Wet) 2 .times. 2 raft
anodized >20 lbs 0-0.5 lbs 0-0.5 lbs aluminum 2 .times. 2 no
raft anodized >20 lbs >20 lbs 0-0.5 lbs aluminum 2 .times. 2
no raft Course Grind -- >20 lbs 0-0.5 lbs textured glass 3
.times. 3 raft anodized >20 lbs >20 lbs 0-0.5 lbs aluminum 3
.times. 3 no raft anodized >20 lbs 19 lbs 0-0.5 lbs aluminum
[0047] In some embodiments, an adhesive described herein has a
bonding strength that is at least about 10 times greater at
100.degree. C. than at room temperature (about 23.degree. C.). In
some embodiments, the bonding strength is at least about 15 times
greater or at least about 20 times greater at 100.degree. C. than
at room temperature. In some embodiments, an adhesive has a bonding
strength about 10-50 times greater at 100.degree. C. than at room
temperature. In some embodiments, an adhesive has a bonding
strength about 2-10 times greater at 100.degree. C. than at room
temperature.
[0048] In addition, in some embodiments, an adhesive described
herein has a bonding strength that is at least about 10 times
greater when dry at 23.degree. C. than when wet at 23.degree. C.,
where the terms "dry" and "wet" are as described above. In some
embodiments, the bonding strength is at least about 15 times
greater or at least about 20 times greater when dry at 23.degree.
C. than when wet at 23.degree. C. In some embodiments, an adhesive
has a bonding strength about 10-50 times greater when dry at
23.degree. C. than when wet at 23.degree. C. In some embodiments,
an adhesive has a bonding strength about 2-10 times greater when
dry at 23.degree. C. than when wet at 23.degree. C.
[0049] Moreover, in some embodiments, an adhesive described herein
has a glass transition temperature below the temperature
encountered during the print process. For example, in some
embodiments, an adhesive has a glass transition temperature below
about 120.degree. C. or below about 100.degree. C. In some
embodiments, an adhesive has a glass transition temperature between
about 50.degree. C. and about 90.degree. C. or between about
60.degree. C. and about 80.degree. C. In some embodiments, a film
of an adhesive described herein has a rubbery consistency above its
glass transition temperature, providing tackiness throughout the
print process, even upon evaporation of any solvent such as water
present in the adhesive. In some embodiments, an adhesive has
increased tackiness above its glass transition temperature. In some
embodiments, an adhesive has reduced tackiness or a hard or glassy
consistency below its glass transition temperature, permitting the
adhesive to act as a releasing agent.
[0050] Adhesives having adhesive properties described herein, in
some embodiments, permit adhesion of a print material or printed
part to a print pad throughout the print process until the part is
complete. In some embodiments, use of an adhesive described herein
prevents distortion or curling of the bottom of a part. Further, in
some embodiments, use of an adhesive described herein permits print
materials and/or printed parts to be removed or peeled from the
print pad easily, without breaking, and/or without the use of
tools.
[0051] Further, in some embodiments, an adhesive described herein
has a high thermal or heat resistance. In some embodiments, an
adhesive has a decomposition temperature greater than the
temperature encountered by the adhesive during the print process.
In some embodiments, an adhesive has a decomposition temperature
greater than about 150.degree. C. or greater than about 200.degree.
C. In some embodiments, an adhesive has a decomposition temperature
greater than about 300.degree. C. In some embodiments, an adhesive
has a decomposition temperature between about 150.degree. C. and
about 350.degree. C. or between about 200.degree. C. and about
300.degree. C.
[0052] Moreover, in some embodiments, an adhesive described herein
is capable of being applied to a print pad using a dispenser such
as a dauber top applicator. In some embodiments, for instance, a
dispenser such as a squeezable bottle with an applicator tip may be
turned upside down, squeezed, and moved along the top surface of
the print pad either prior to placement of the print pad on the 3D
printer (in the case of a removable print pad, for example) or
while the print pad is on the 3D printer. If desired, the adhesive
can be applied using a swirl pattern, stripe pattern, or other
pattern.
[0053] In some embodiments, an adhesive described herein is a
viscous gel at room temperature. The dynamic viscosities of some
adhesives described herein were measured in a mariner consistent
with ASTM D2983. Specifically, the dynamic viscosities were
measured using a Brookfield Model DV-E Viscometer and a Brookfield
Refrigerated Circulating Bath. Samples of adhesive (approximately
10 mL) were placed in the viscometer test chamber and maintained at
30.degree. C. using the circulating bath. To determine the dynamic
viscosity, a number 15 spindle set to a rotational speed of 50 rpm
was used.
[0054] In some embodiments, an adhesive described herein has a
dynamic viscosity at 30.degree. C. between about 2500 and about
10,000 centipoise (cP) when measured as described herein. In some
embodiments, an adhesive has a dynamic viscosity at 30.degree. C.
between about 2500 and about 4500 cP, between about 3000 and about
9000 cP, between about 3000 and about 4000 cP, or between about
4500 and about 8000 cP when measured as described herein. In some
embodiments, an adhesive has a dynamic viscosity at 30.degree. C.
between about 10,000 and about 25,000 cP when measured as described
herein. In some embodiments, an adhesive has a dynamic viscosity at
30.degree. C. between about 12,000 and about 20,000 cP, between
about 14,000 and about 22,000 cP, or between about 15,000 and about
20,000 cP when measured as described herein.
[0055] In some embodiments, the viscosity of an adhesive described
herein is selected to provide a desired adhesive layer thickness
when the adhesive is applied to a print pad described herein. For
example, in some embodiments, an adhesive having a dynamic
viscosity greater than about 4000 cP at 30.degree. C. provides a
uniform adhesive layer thickness of about 10 .mu.m when applied to
a print pad described herein. In some embodiments, an adhesive
having a dynamic viscosity between about 7000 and about 10,000 cP
at 30.degree. C. can provide a uniform adhesive layer thickness of
about 10-12 .mu.m when the adhesive is applied to a textured glass
print pad. Moreover, in some embodiments, an adhesive is applied to
a print pad in an amount between about 2.5 and about 5 mg/cm.sup.2
(where the mass is the adhesive mass and the area is the area of
the print pad to which the adhesive is applied).
[0056] In addition, in some embodiments, an adhesive described
herein does not coagulate during a print process described herein
sufficiently to interfere with the print nozzle, even if solvent
present in the adhesive evaporates during the print process.
[0057] Further, in some embodiments described herein, an adhesive
has a high water spread or wetting ability, including on a print
pad described herein. In some embodiments, an adhesive spreads
water or wets uniformly, including without dewetting. In some
embodiments, an adhesive is highly hydrophilic and/or has a high
surface energy. The water spread or wetting ability of an adhesive
described herein, in some embodiments, can be determined by
measuring the diameter of a droplet of deionized water disposed on
a layer of the adhesive on the surface of a print pad. In some
embodiments, for instance, a water droplet having a volume of about
0.01 mL spreads to a final diameter of about 7-9 mm when disposed
on an adhesive described herein disposed on a textured glass print
pad. In some embodiments, the diameter of a deionized water droplet
on a layer of adhesive described herein disposed on a print pad
described herein is at least about 1.5 times the diameter of an
equivalent water droplet on the bare surface of the print pad. In
some embodiments, the diameter of a deionized water droplet on a
layer of adhesive is at least about 3 times or at least about 5
times the diameter of the droplet on the bare print pad. In some
embodiments, the diameter of a deionized water droplet on a layer
of adhesive is between about 1.5 times and about 3 times, between
about 2 times and about 5 times, between about 3 times and about 5
times, or between about 5 times and about 10 times the diameter of
the droplet on the bare print pad.
[0058] In some embodiments, an adhesive described herein is water
soluble. A water-soluble adhesive, for reference purposes herein,
has a solubility in water at 25.degree. C. of greater than 10 mass
percent, greater than 30 mass percent, greater than 50 mass
percent, or greater than 90 mass percent, based on the mass of the
adhesive. Moreover, in some embodiments, an adhesive is water
soluble before, during, and after being used in a print process,
even if some or all of the solvent present in the adhesive
evaporates during the print process. In addition, in some
embodiments, an adhesive described herein is biodegradable. In some
embodiments, an adhesive described herein is safe and non-toxic to
humans. Therefore, in some embodiments, an adhesive described
herein can be safely dissolved and/or rinsed away from a print pad
or finished part, including down the sink and/or into the
environment.
[0059] Further, an adhesive described herein can have any
combination of components and properties described herein not
inconsistent with the objectives of the present invention. In some
embodiments, for example, an adhesive exhibits both water
solubility and hardening upon cooling below its glass transition
temperature. In some embodiments, an adhesive exhibits both a high
surface energy and increased tackiness in a rubbery state. In some
embodiments, an adhesive is a viscous gel that exhibits a
water-sensitive and/or temperature-dependent adhesion or bonding
strength. In some embodiments, an adhesive is biodegradable, has
water spreading properties described herein, has an adhesion or
bonding strength or other adhesion property described herein, and
has a high heat resistance.
[0060] Moreover, the properties of an adhesive described herein can
be selected or tuned by altering the relative amounts, chemical
identities, and/or molecular weights of the various components of
an adhesive described herein. For example, in some embodiments, the
adhesion or bonding strength of an adhesive can be selected by
altering the relative amounts and chemical identities of the first
polymeric component and the second polymeric component. A PVOH
described herein, for instance, can be selected as the first
polymeric component due to its crystallinity or molecular weight
and can be used in a specific amount relative to a second polymeric
component to provide a desired amount of adhesiveness or tackiness
or water solubility or a desired viscosity. In addition, in some
embodiments, the relative amounts of the first and second polymeric
components are selected based on a desired temperature-dependent or
water-sensitive adhesive property, including in combination with a
specific print pad and/or print material described herein. For
example, in some embodiments, the amount of a PVOH and/or of a
second polymeric component in an adhesive described herein may be
altered based on whether an anodized aluminum print pad, textured
glass print pad, or polycarbonate print pad is used, and/or whether
the print pad is heated or unheated during the print process.
[0061] Adhesives described herein can be made in any manner not
inconsistent with the objectives of the present invention. For
example, in some embodiments, an adhesive is made by combining,
stirring, blending, shaking, or mixing the various components of
the adhesive described herein, with or without heating. In some
embodiments, for instance, an adhesive is made by combining and
mixing a first polymeric component described herein (such as a
PVOH), a second polymeric component described herein (such as a
poly(2-oxazoline), poly(2-ethyl-2-oxazoline,
poly(2-ethyl-oxazoline), polyvinyl acetate, polymethyl acrylate, or
polylactic acid), and a solvent described herein (such as distilled
water). In some embodiments, an adhesive is made by combining and
mixing the components of Table II in the amounts indicated, where
all listed amounts correspond to weight percents based on the total
weight of the adhesive. Moreover, an adhesive described herein can
be made manually or by machine, including in an automated
process.
TABLE-US-00002 TABLE II Second Polymeric DI Adhesive PVOH Component
Water Surfactant Preservative 1 2-50 2-50 50-95 0.01-1 0.01-1 2
5-50 2-50 50-95 -- -- 3 3-10 30-50 50-95 0.01-0.05 0.01-0.05 4 3-10
30-50 50-95 -- -- 5 20-40 5-15 50-95 0.01-0.05 0.01-0.05 6 20-40
10-30 50-95 -- -- 7 -- 5-60 50-95 0.0-0.05 0.0-0.05 8 -- 30-50
50-95 0.01-1 0.01-1
[0062] In some embodiments, the PVOH comprises amorphous PVOH, and
the second polymeric component does not comprise PVOH. In some
embodiments, the second polymeric component comprises
poly(2-oxazoline), poly(2-ethyl-2-oxazoline), or
poly(2-ethyl-oxazoline).
II. Methods of Printing a 3D Article
[0063] In another aspect, methods of printing a 3D article or
object are described herein. In some embodiments, a method of
printing a 3D article comprises applying an adhesive to a build
surface of a print pad of a 3D printer, such as a Cube.RTM. 3D
Printer manufactured by 3D Systems of Rock Hill, S.C. The adhesive
can comprise any adhesive described hereinabove in Section I. For
example, in some embodiments, the adhesive comprises a first
polymeric component comprising a poly(vinyl alcohol) and a second
polymeric component. In some embodiments, the first polymeric
component and the second component are not the same material but
are instead separate components of the adhesive. In addition, the
adhesive can be applied to the build surface of the print pad in
such a manner as to provide a layer of adhesive. The layer can be
continuous or discontinuous and, in some embodiments, can be
substantially uniform, where a "substantially uniform" layer
exhibits a thickness that varies by less than about 10 percent or
less than about 5 percent. Moreover, the layer of adhesive can also
exhibit any other feature or property of a layer of adhesive
described hereinabove in Section I. Thus, as described herein, the
present invention also provides a print pad comprising a layer of
adhesive disposed on a build surface of the print pad. The print
pad can comprise any print pad described hereinabove in Section I,
such as an aluminum print pad, glass print pad, or polycarbonate
print pad of a 3D printer.
[0064] In some embodiments, a method described herein further
comprises selectively depositing layers of a fluid ink or print
material onto the build surface of the print pad to form the 3D
article. The print material can comprise any print material
described herein. In some embodiments, the layers of the print
material are deposited according to an image of the 3D article in a
computer readable format. In some embodiments, the print material
is deposited according to preselected computer aided design (CAD)
parameters.
[0065] Moreover, in some embodiments described herein, the print
material exhibits a phase change upon deposition and/or solidifies
upon deposition. In some embodiments, the temperature of the
printing environment can be controlled so that the jetted droplets
of print material solidify on contact with the receiving
surface.
[0066] In some embodiments, a method of printing a 3D article
further comprises supporting at least one of the layers of the
print material with a support material, including a support
material described herein. A support material, in some embodiments,
can be deposited in a manner consistent with that described herein
for the print material. The support material, for example, can be
deposited according to the preselected CAD parameters such that the
support material is adjacent or continuous with one or more layers
of the print material. Jetted droplets of the support material, in
some embodiments, solidify or freeze on contact with the receiving
surface.
[0067] Layered deposition of the print material and support
material can be repeated until the 3D article has been formed.
[0068] In some embodiments, a method described herein further
comprises removing the printed 3D article from the print pad.
Moreover, in some embodiments, removing the 3D article from the
print pad comprises altering an adhesive property of the adhesive,
including in a manner described hereinabove in Section I. For
example, in some embodiments, the adhesion strength or bonding
strength of the adhesive with the print pad or 3D article is
altered by changing the temperature of the adhesive or exposing the
adhesive to water. In some embodiments, the adhesion strength or
bonding strength of the adhesive is reduced by reducing the
temperature or exposing the adhesive to water. In some embodiments,
the adhesion strength or bonding strength of the adhesive is
reduced by submerging the print pad and printed 3D article in
water. In some embodiments, the water is warm water, such as water
at a temperature between about 45.degree. C. and about 90.degree.
C., between about 50.degree. C. and about 85.degree. C., or between
about 55.degree. C. and about 70.degree. C.
[0069] Various embodiments of the invention have been described in
fulfillment of the various objectives of the invention. It should
be recognized that these embodiments are merely illustrative of the
principles of the present invention. Numerous modifications and
adaptations thereof will be readily apparent to those skilled in
the art without departing from the spirit and scope of the
invention.
* * * * *