U.S. patent application number 11/466154 was filed with the patent office on 2007-03-01 for infiltrated articles prepared by a laser sintering method and method of manufacturing the same.
This patent application is currently assigned to VALSPAR SOURCING, INC.. Invention is credited to Paul Boehler, Raffaele Martinoni.
Application Number | 20070045891 11/466154 |
Document ID | / |
Family ID | 37561128 |
Filed Date | 2007-03-01 |
United States Patent
Application |
20070045891 |
Kind Code |
A1 |
Martinoni; Raffaele ; et
al. |
March 1, 2007 |
Infiltrated Articles Prepared by a Laser Sintering Method and
Method of Manufacturing the Same
Abstract
A composition and method of infiltrating an article of
manufacture prepared by a laser sintering process is disclosed. The
infiltration process maintains the dimensions and flexibility of
the article, increases the strength of the article, and improves
the physical and esthetic properties of the article.
Inventors: |
Martinoni; Raffaele;
(Wolfhausen, CH) ; Boehler; Paul; (Uetikon,
CH) |
Correspondence
Address: |
VALSPAR SOURCING, INC.
1101 SOUTH THIRD STREET
MINNEAPOLIS
MN
55415
US
|
Assignee: |
VALSPAR SOURCING, INC.
Minneapolis
MN
|
Family ID: |
37561128 |
Appl. No.: |
11/466154 |
Filed: |
August 22, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60710499 |
Aug 23, 2005 |
|
|
|
Current U.S.
Class: |
264/128 |
Current CPC
Class: |
B33Y 80/00 20141201;
B29C 64/165 20170801; B29C 64/153 20170801; B33Y 40/00
20141201 |
Class at
Publication: |
264/128 |
International
Class: |
B27N 5/00 20060101
B27N005/00 |
Claims
1. A method of infiltrating an article prepared by a laser
sintering method comprising the steps of: (a) applying a liquid
infiltrant to the article for a sufficient time to allow the liquid
infiltrant to infiltrate the article, said liquid infiltrant
comprising: (i) an elastomeric material; (ii) a vehicle; and (iii)
an optional colorant; (b) drying the infiltrated article of step
(a); (c) optionally, repeating steps (a) and (b) until the article
is infiltrated to a desired degree.
2. The method of claim 1 wherein dimensions of the article after
infiltration differ from the original dimensions by less than
1%.
3. The method of claim 1 wherein the method is free of a
crosslinking step.
4. The method of claim 1 wherein the article is a flexible article,
and the flexibility of the article after infiltration is
essentially identical to the flexibility of the article prior to
infiltration.
5. The method of claim 1 wherein the elastomeric material is
present in the liquid infiltrant in an amount of about 20% to about
60% by weight of the liquid infiltrant.
6. The method of claim 1 wherein the elastomeric material comprises
a naturally occurring resin, a synthetic resin, or a mixture
thereof.
7. The method of claim 1 wherein the naturally occurring resin
comprises a natural rubber latex.
8. The method of claim 7 wherein the natural rubber latex is
prevulcanized.
9. The method of claim 6 wherein the synthetic resin comprises
styrene-butadiene rubber, butadiene rubber, isoprene rubber,
poly(ethylene-co-propylene-co-diene) rubber, butyl rubber, nitrile
rubber, acrylonitrile-butadiene rubber, acrylonitrile-chloroprene
rubber, chloroprene rubber, a silicone, a fluorocarbon elastomer,
poly(vinylidene fluoride-co-hexafluoropropene), a polysulfide
rubber, a polyurethane, acrylate-butadiene rubber,
ethylene-propylene rubber, styrene-isoprene rubber,
vinylpyridine-butadine, vinylpyridine-styrene-butadiene,
carboxylic-acrylonitrile-butadiene, carboxylic-styrene-butadiene,
chlorobutyl rubber, bromobutyl rubber, a poly(propylene oxide), a
polyesterurethane, a polyetherurethane, an acrylic elastomer, an
ethylene-acrylic elastomer, a chlorosulfonated polyethylene, a
polyether, and mixtures thereof.
10. The method of claim 1 wherein the vehicle of the liquid
infiltrant comprises water.
11. The method of claim 10 wherein the vehicle further comprises an
organic solvent.
12. The method of claim 11 wherein the organic solvent comprises an
alcohol, a ketone, a glycol, a glycol ether, or mixtures
thereof.
13. The method of claim 1 wherein the colorant is present in the
liquid infiltrant in an amount of about 0.1% to about 15%, by
weight.
14. The method of claim 1 wherein the infiltrated article is dried
in step (b) at a temperature of about 20.degree. C. to about
80.degree. C.
15. The method of claim 1 wherein the infiltrated article is dried
in step (b) by applying a vacuum.
16. The method of claim 1 wherein the liquid infiltrant is applied
to the article by dipping the article into the liquid
infiltrant.
17. The method of claim 1 wherein the liquid infiltrant is applied
to the article by spraying the liquid infiltrant onto the
article.
18. An infiltrated article prepared by the method of claim 1.
19. The infiltrated article of claim 18 wherein the article is
substantially nonporous.
20. The infiltrated article of claim 18 wherein the article
exhibits improved tear strength and elongation at break compared to
the article prior to infiltration.
21. The infiltrated article of claim 18 wherein the article is
infiltrated through the total volume of the article.
22. The infiltrated article of claim 18 wherein less than the total
volume of the article is infiltrated.
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of Provisional
Application No. 60/710,499 filed on Aug. 23, 2005 by Martinoni, et
al., and entitled "Infiltrated Articles Prepared by a Laser
Sintering Method and Method of Manufacturing the Same," which is
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a composition and method of
infiltrating an article of manufacture prepared by a laser
sintering process. More particularly, the present invention relates
to a composition and method of infiltrating an article prepared by
a laser sintering process, wherein the dimensions of the article
are retained during the infiltration process, the flexibility of a
flexible article is maintained, and the physical and esthetic
properties of the article are improved.
BACKGROUND OF THE INVENTION
[0003] Laser sintering (LS), also termed selective laser sintering,
is a process whereby a dispenser deposits a layer of powdered
material into a target area. A laser control mechanism, which
typically includes a computer that houses the design of a desired
article, modulates and moves a laser beam to selectively sinter the
powder layer within the defined boundaries of the design. The
control mechanism operates the laser to selectively sinter
sequential powder layers, eventually producing a completed article
comprising a plurality of layers sintered together.
[0004] More particularly, laser sintering generally is performed
according to the following steps:
[0005] 1. A piston of a process chamber is lowered by one layer
thickness, and simultaneously, a piston of a cartridge containing a
particulate material is raised;
[0006] 2. The particulate material is introduced into the process
chamber, and a leveling roller spreads the particulate material
evenly over a build surface of the process chamber;
[0007] 3. The particulate material then is heated to a temperature
near, but below, its softening point;
[0008] 4. A laser beam then traces a predetermined cross section of
an article on the layer of heated particulate material in the build
surface, thus forming a solid layer; and
[0009] 5. Steps 2 through 4 are repeated until manufacture of a
three-dimensional article is completed.
[0010] Particulate material in areas that have not been sintered by
the laser remains unfused and in place, and acts as a natural
support for the article being manufactured. Accordingly, no need
exists for support structures during manufacture of the article.
After cooling, the article of manufacture and the unfused
particulate material are removed from the process chamber, and the
article of manufacture is separated from the unfused particulate
material, i.e., "breakout." FIGS. 1 and 2 are schematics
illustrating the LS process for the manufacture of an article
having a complex shape. LS technology has enabled the direct
manufacture of three-dimensional articles of high resolution and
dimensional accuracy from a variety of materials including polymers
and composite materials, such as polymer coated metals and
ceramics.
[0011] A detailed description of LS technology can be found in U.S.
Pat. Nos. 4,247,508; 4,863,538; and 5,017,753, each incorporated
herein by reference. Clausen et al. U.S. Pat. No. 6,110,411, also
incorporated herein by reference, provides a detailed description
of the selective layer sintering process, and also discloses
laser-sinterable thermoplastic compositions for use in the
process.
[0012] Articles manufactured using LS technology can be rigid or
flexible depending upon the identity of the particulate material
used in the LS process. For example, if the particulate material
contains a metal or a ceramic, the article is typically rigid.
Flexible articles are prepared by an LS technique when polymeric
materials such as those disclosed in WO 2005/025839 and U.S. Pat.
No. 6,110,411 are used as the particulate material.
[0013] Both rigid and flexible articles manufactured by LS
technology are sufficiently porous such that undesirable physical
and esthetic properties can result. Porous articles having
inadequate strength, unsatisfactory hardness, low abrasion
resistance, and/or rough surface finish, are significantly limited
with respect to the practical applications in which such articles
can be used. Therefore, a method of improving the physical and
esthetic properties of articles manufactured by LS technology
remains a need in the art.
[0014] One means of achieving improved physical and esthetic
properties is to infiltrate the article with a composition that at
least partially fills the voids in the article. Infiltration is a
long-practiced process to increase the strength of a porous
material. However, prior infiltration methods and compositions have
disadvantages, such as involving a complex procedure or altering
the dimensions or physical properties of an article prepared by an
LS process.
[0015] The present invention is directed to compositions and
methods of infiltrating articles manufactured by an LS process that
overcome the disadvantages associated with prior infiltration
compositions and methods.
SUMMARY OF THE INVENTION
[0016] The present invention is directed to an improved method of
infiltrating an article prepared by an LS process. For articles
manufactured using an LS process, the present method retains the
flexibility of the article, maintains the dimension of the article,
and improves the strength and esthetics of the article.
[0017] Accordingly, one aspect of the present invention is to
provide a liquid infiltrant for infiltrating an article
manufactured using an LS process. The liquid infiltrant comprises
an elastomeric polymeric material, such as a natural latex, in a
suitable vehicle. Preferably, the vehicle comprises water.
[0018] Another aspect of the present invention is to provide a
method of infiltrating an article manufactured using an LS process
comprising contacting the article with a liquid infiltrant
comprising an elastomeric polymeric material. The liquid infiltrant
is applied to the article one or more times to achieve the desired
degree of infiltration. Drying of the article treated with the
liquid infiltrant, either air drying at room temperature or with
mild heating, provides an infiltrated article of the present
invention. The present infiltration method preferably does not
utilize a crosslinking step.
[0019] Another aspect of the present invention is to provide an
infiltrated article prepared by an LS process comprising:
[0020] (a) applying a liquid infiltrant to the article, said liquid
infiltrant comprising an elastomeric polymer, an optional colorant,
and a suitable vehicle;
[0021] (b) maintaining application of the liquid infiltrant to the
article for a sufficient time to allow the liquid infiltrant to
penetrate the article;
[0022] (c) drying the treated article of step (b); and
[0023] (d) optionally repeating steps (a) through (c) until the
article is infiltrated to a desired degree or with a desired amount
of the liquid infiltrant.
[0024] In another aspect of the present invention, the liquid
infiltrant and method of infiltrating the article substantially
retain the original dimensions and flexibility of the article,
while increasing the strength and durability of the article. In yet
another aspect of the present invention, the esthetics of the
article are improved.
[0025] Still another aspect of the present invention is to provide
a composition and method of infiltrating a flexible article
prepared by an LS process from a particulate material comprising a
block copolymer, wherein the flexibility of the article is
maintained after infiltration.
[0026] Yet another aspect of the present invention is to provide an
article manufactured by an LS process and subjected to an
infiltration process, said article having dimensions and a
resolution essentially equivalent to that possessed by the article
prior to the infiltration process.
[0027] These and other novel aspects and advantages of the present
invention will become more apparent from the following detailed
description of the preferred embodiments taken in conjunction with
the figures.
BRIEF DESCRIPTION OF THE FIGURES
[0028] FIGS. 1 and 2 are schematics illustrating the laser
sintering process; and
[0029] FIG. 3 illustrates infiltrated and uninfiltrated
articles.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] The present invention is directed to a composition and
method of infiltrating an article manufactured using an LS process.
The infiltration process comprises easy and low-cost steps that
increase the strength and durability of the article, while
maintaining the dimensions, resolution, and flexibility of the
article, and improving the esthetics of the article.
[0031] An article first is built from a particulate polymeric build
material using an LS process known in the art. Often, the build
material is a thermoplastic polymeric material that provides a
flexible article. However, the present method also is useful for
infiltrating rigid articles, for example, an article prepared in an
LS process using a thermosetting polymeric material.
[0032] Nonlimiting examples of particulate polymeric materials
useful in an LS process are disclosed in WO 2005/025839 and in U.S.
Pat. No. 6,110,411. The polymeric materials disclosed therein are
thermoplastic block copolymers, which contain discrete segments
along the polymer chain characterized as soft and hard segments.
These segments are bonded one to another, randomly, by condensation
polymerization such that the head of one segment is joined to the
tail of another segment.
[0033] Nonlimiting examples of thermoplastic block copolymers that
can be used in an LS process include, but are not limited to,
copolymers sold under the tradenames HYTREL (E.I. duPont), SANIFLEX
(Wilden), ECDEL (Eastman Chemicals), GAFLEX (Celanese), LOMOD
(General Electric), ARNITEL (Dutch State Mines), PEBAX (Arkema),
ESTANE (B.F. Goodrich), ESTAMID (Dow), RITEFLEX (Ticona GmbH),
PELLATHANE (Dow Chemical), Q-THANE (K.J. Quinn), and TEXIN (Mobay).
HYTREL and RITEFLEX, for example, are polyether-ester elastomers;
ARNITEL is a polyester-ester elastomer; PEBAX is a polyether-amide
elastomer; ESTANE is a polyether-urethane elastomer; ESTAMID is a
polyester-amide; and TEXIN is a polyester-urethane.
[0034] Specific block copolymers useful in an LS process include,
but are not limited to, HYTREL.RTM. Types 4069, 4556, 5526, 4059FG,
G4778, G4774, 555HS, and 6359FG, and RITEFLEX.RTM. Type 663.
Especially useful block copolymers in an LS process are HYTREL.RTM.
4068FG and RITEFLEX.RTM. 640. HYTREL.RTM. 4068FG is a thermoplastic
block copolymer having a hard (i.e., crystalline) segment of
polybutylene phthalate and a soft (i.e., amorphous) segment based
on a long chain polyalkylenether glycol.
[0035] The infiltration method of the present invention is not
limited to articles manufactured in an LS process using a flexible
block copolymer. Other polymeric materials known for use in an LS
process also can be used, regardless of whether the article is
flexible or inflexible. For example, a polyamide can be used as the
polymeric particulate material in the LS process. Examples of
useful polyamides include, but are not limited to, nylon 12 and
nylon 11, sold as DURAFORM PA12, a polylaurolactam, DURAFORM PA 11,
EOSINT PA, and RILSAN PA-11. Other useful polyamides include, but
are not limited to, nylon 6, nylon 66, nylon 610, nylon 612,
copolymerized nylons, and mixtures thereof. Another nonlimiting
example of a nylon that can be used is the ELVAMIDE.RTM. line of
nylon resins, available from DuPont Co., Wilmington, Del., for
example, ELVAMIDE.RTM. 8061, a polyamide terpolymer of nylon 6,
nylon 66, and nylon 610.
[0036] Additional useful polymeric particulate materials are
end-capped polyamides, for example, the VESTOSINT line of
end-capped nylons, e.g., VESTOSINT X-1546 LV, VESTOSINT X-1546 HV,
and VESTOSINT X4175. Additional polymeric particulate materials
used to manufacture an article using LS processes include, but are
not limited to, a polyethylene, a polypropylene, a polyvinyl
acetate, a polymethacrylate, a phenolic, an ionomer, a polyacetal,
an acrylonitrile-butadiene-styrene copolymer, a polyimide, a
polycarbonate, a polyurethane, copolymers of the above, and
mixtures thereof.
[0037] Thermosetting resins also can be used as the polymeric
particulate material. Thermosetting resins provide an inflexible
article in an LS process, and include, but are not limited to,
epoxies, acrylates, vinyl ethers, unsaturated polyesters,
bismaleimides, and mixtures thereof. A mixture of thermoplastic
resins, or thermosetting resins, or thermoplastic resin and
thermosetting resin can be used as the polymer particulate material
in the LS process.
[0038] After preparation of an article by an LS process, the
article is subjected to an infiltration process of the present
invention. The article is infiltrated by applying a liquid
infiltrant to the article, once or a plurality of times, until the
article is infiltrated to a desired degree. FIG. 3a illustrates a
section of an article 1 prepared by an LS process prior to
infiltration. In the uninfiltrated article 1, voids 5 exist between
particles of fused particulate material 2. FIG. 3b illustrates a
fully infiltrated article 10 in which voids 5 of FIG. 3a are
completely filled by infiltrant 6. FIG. 3c illustrates an article
20 that is partially infiltrated by infiltrant 6.
[0039] The degree of infiltration, either partial or total, is
achieved by a selection of the number of times the liquid
infiltrant is applied to the article, and the length of time that
the liquid infiltrant is allowed to contact the article. Typically,
the liquid infiltrant is applied to the article one to four times,
for about 30 seconds to 5 minutes per application. After an
application of the liquid infiltrant to the article, the article
can be air dried or, preferably, dried under vacuum and/or moderate
heating, i.e., about 20.degree. C. to about 40.degree. C., to
remove a substantial amount of the vehicle from the article. After
the final application of the liquid infiltrant to the article, the
article is dried under vacuum and/or heating, e.g., about
30.degree. C. to about 80.degree. C., and most preferably about
40.degree. C. to about 70.degree. C., for a sufficient time to
provide a tack-free article.
[0040] Maintaining the dimensions of an article prepared in an LS
process is important in the design of the article. Laser sintering
provides a high resolution article of accurate and precise
dimensions. If subsequent process steps alter the dimensions of the
article, these changes must be known and factored into the design
of the LS process. Using the present infiltration process
eliminates difficult design concerns because the article can be
dimensioned to essentially exact specifications at the design stage
without a concern of dimension and resolution changes during the
infiltration step.
[0041] The liquid infiltrant applied to the article can be solvent
based or aqueous based. Aqueous liquid infiltrants are preferred
because such infiltrants are less prone to swelling the article to
any appreciable degree. Accordingly, the dimensions and the
resolution of the article remain essentially unchanged during the
infiltration process. Aqueous liquid infiltrants may optionally
contain a polar organic solvent, such as an alcohol, a ketone, a
glycol, a glycol ether, or a mixture thereof, to assist in
dispersing or solubilizing the elastomeric material present in the
liquid infiltrant.
[0042] Liquid infiltrants that are solvent based, such as
hydrocarbon based, also can be used provided the solvent present in
the liquid infiltrant is substantially inert with respect to the
material of construction of the article, e.g., the solvent does not
appreciably dissolve or swell the article.
[0043] A liquid infiltrant useful in the present method comprises
an elastomeric material in a vehicle. The elastomer can be a
naturally occurring resin, a synthetic resin, or a mixture thereof.
In particular, one preferred elastomeric material for use in the
liquid infiltrant is a natural rubber latex, and more preferably a
prevulcanized natural rubber latex. Examples of useful natural
latexes include Latex FA, Latex LATZ, REVULTEX MR, REVULTEX HR,
REVULTEX LA, REVULTEX LAN, REVULTEX MLA, REVULTEX HLA, REVULTEX
Standard, and REVULTEX LCS, all available from Safic-Alcan, Paris,
France. These natural latexes contain about 60% by weight dry
rubber content. Additional useful natural latexes are available
under the G-TEX, GIVUL, and LOPROTEX tradenames, for example, G-TEX
HA, LATZ, and MA; GIVUL LR, LAN 2056, MR, HR, LA, HM, LP2, LPT2,
and LTS-LA; and LOPROTEX LPX, available from Getahindus, Malaysia
and Southland Latex Co., Ltd., Thailand.
[0044] Synthetic elastomers can be used together with, or in place
of, a natural latex. For example, the following synthetic
elastomers can be used individually or in any compatible
combination: styrene-butadiene rubber, butadiene rubber, isoprene
rubber, EP(D)M (i.e., poly(ethylene-co-propylene-co-diene), butyl
rubber, nitrile rubber (e.g., acrylonitrile-butadiene or
acrylonitrile-chloroprene), chloroprene rubber, a silicone, a
fluorocarbon elastomer (e.g., poly(vinylidene
fluoride-co-hexafluoropropene), a polysulfide rubber, a
polyurethane, acrylate-butadiene rubber, ethylene-propylene rubber,
styrene-isoprene rubber, vinylpyridine-butadine,
vinylpyridine-styrene-butadiene,
carboxylic-acrylonitrile-butadiene, carboxylic-styrene-butadiene,
chlorobutyl rubber, bromobutyl rubber, a poly(propylene oxide), a
polyesterurethane, a polyetherurethane, an acrylic elastomer, an
ethylene-acrylic elastomer, a chlorosulfonated polyethylene, a
polyether, and mixtures thereof.
[0045] Examples of commercially available chloroprene rubbers
include NEOPRENE 115, 400, 571, 622, 654, 671A, 735A, 750, and 842A
(all commercially available from DuPont Elastomers as aqueous
dispersions).
[0046] In some embodiments, the infiltrated article is suitable for
contact with food or beverage products. In such embodiments, the
liquid infiltrant preferably includes an elastomeric material
suitable for contacting food or beverage products. Examples of
preferred elastomeric materials suitable for use in such
embodiments include suitable chloroprene rubbers such as, for
example, suitable polychloroprene and/or copolymers of chloroprene
and one or more other suitable monomers (e.g., methacrylic acic,
2,3 dichloro 1,3-butadiene, etc.). NEOPRENE 571 (commercially
available from DuPont Elastomers as aqueous dispersions) is a
specific preferred example of a commercially available chloroprene
rubber suitable for use in food or beverage applications.
[0047] The liquid infiltrant typically contains about 20% to about
60%, by weight, of the elastomeric material. The amount of
elastomeric material present in the liquid infiltrant is related to
the viscosity of the liquid infiltrant because if the viscosity is
too high, the liquid infiltrant may not sufficiently penetrate the
article. The amount of elastomeric material in the liquid
infiltrant also is related to the porosity of the article and the
desired degree of infiltration.
[0048] In addition to the elastomeric material, the liquid
infiltrant comprises a vehicle. As discussed above, the preferred
vehicle is aqueous, and comprises a majority of water and
optionally a polar organic solvent, such as an alcohol, ketone,
glycol, and/or glycol ether, as process aids. Nonpolar solvents can
be used as the vehicle provided the solvent does not adversely
affect the article. In particular, the vehicle is selected after
considering the identity of the elastomeric material in the liquid
infiltrant and the material of construction of the article, such
that the original dimensions of the article are changed by less
than 1% and the elastomeric material effectively infiltrates the
article.
[0049] In addition to the elastomeric material and the vehicle, the
liquid infiltrant preferably comprises an optional antifoam
additive, such as DEE FO.RTM. 215 (a slightly emulsifiable mineral
oil), Ultra Additives, Inc., Bloomfield, N.J., or ADVANTAGE.RTM.
357 Defoamer (an oil-based antifoaming agent), Hercules, Inc.,
Wilmington, Del., and an optional flow agent, such as TEGO.RTM.
Twin 4000 (a siloxane surfactant having wetting and defoaming
properties), Tego Chemie Service GmbH, Essen, Germany or BYK-381
(an acrylic leveling additive for aqueous systems), BYK Chemie,
Wesel, Germany, each in an amount to perform its intended function,
if present at all, without adversely affecting the liquid
infiltrant or the article to be infiltrated. For example, each of
the optional antifoam additive and optional flow agent are present
in an amount of 0% to about 0.5%, by weight, of the liquid
infiltrant.
[0050] Another optional ingredient in the liquid infiltrant is a
colorant. An article manufactured by an LS process typically has an
opaque appearance because of the presence of minute air bubbles in
the article. After infiltration using the present method, the
article has a transparent appearance because the voids of the
article have been infiltrated. By including a colorant in the
liquid infiltrant, the liquid infiltrant imparts a glossy color to
the article.
[0051] The colorant can be any dye or pigment, organic or inorganic
in nature, that is soluble or dispersible in the liquid infiltrant.
The colorant optionally can be iridescent, fluorescent,
phosphorescent, or conductive. The colorant can be, for example, a
color such as cyan, magenta, yellow, black, and mixtures thereof to
produce any desired color. The colorant also can be white in
color.
[0052] The colorant can be from dye classes such as Color Index
(C.I.) dyes, solvent dyes, disperse dyes, modified acid and direct
dyes, and basic dyes. Polymeric colorants also can be used, such as
Blue 92, Ink Red 357, Ink Yellow 1800, and Ink Black 8915-67. Other
yellow, cyan, magenta, and black polymeric colorants can be used
alone or in combination with conventional colorants such as those
disclosed in U.S. Pat. No. 5,372,852. Solvent soluble dyes also can
be used.
[0053] The colorant also can impart conductive properties on the
object, such as by using a metal oxide dye. In addition, if
desired, the colorant can be phosphorescent, thereby emitting light
following exposure to incident radiation if desired.
[0054] The colorant is present, if at all, in a sufficient amount
to impart the desired color degree and color intensity to the
infiltrated article without adversely affecting the article or the
liquid infiltrant as a whole. The colorant typically is added to
the liquid infiltrant as a paste or dispersion of the pigment in an
aqueous or nonaqueous solvent in an amount of about 0.1% to about
15%, as active colorant, by weight of the composition.
[0055] The following is a nonlimiting example of a liquid
infiltrant utilized in the present method. TABLE-US-00001 EXAMPLE 1
Weight % Elastomeric material.sup.1) 80 Antifoam.sup.2) 0.8 Flow
agent.sup.3) 0.2 Colorant.sup.4) 8 Water 11 .sup.1)REVULTEX .RTM.
MR, 60 wt % active, available from Revertex (Malaysia) SDN, BND.,
Johor, Malaysia; .sup.2)DEE Fo 215, 100 wt % active, available from
Ultra Additives; .sup.3)TEGO TWIN 4000, 100 wt % active, available
from Tego Chemie; .sup.4)Pintasol Black E-WL8 (C.I. Number 77266),
57 wt % active, available from Clariant, Leeds, UK.
[0056] The composition of Example 1 was prepared by mixing the
ingredients under constant mixing speed under constant mixing.
After admixing the composition ingredients, the composition was
filtered to remove any particulate or gelled material.
[0057] An article prepared by an LS is infiltrated by applying a
present liquid infiltrant to the article by dipping, brushing, or
spraying. The liquid infiltrant can be applied to the article once
or a plurality of times, and typically is applied two to four
times. The infiltrated article is allowed to dry after each
application at about 20.degree. C. to about 30.degree. C. After the
final application, the infiltrated article is dried at a
temperature of about 30.degree. C. to about 80.degree. C., and more
preferably about 50.degree. C. to about 70.degree. C., for a
sufficient time to provide a tack-free article to the touch. The
specific mode of application, time of application, and drying time
is related to the composition of the liquid infiltrant and to the
structural complexity, thickness, and material of construction of
the article.
[0058] After infiltration of the article, the article has a smooth,
rubber-like feel, regardless of whether the article is flexible or
inflexible. Flexible articles retain their flexibility, and the
elasticity of the elastomeric method of the infiltrant on the
article surface precludes the formation of crack on the
surface.
[0059] Importantly, the infiltrated article essentially retains the
dimensions and resolution of the uninfiltrated article, i.e.,
swelling of the article due to the infiltration process is less
than 1% of article volume. The present infiltration process also
permits coloring of the article with essentially any colorant that
can be solubilized or dispersed in the liquid infiltrant.
[0060] In addition to imparting improved esthetics to the article,
the present infiltration method renders the article substantially
nonporous, e.g., waterproof and airproof, and improves the
mechanical properties of the article, such as an improved tear
strength and elongation at break. The following table illustrates
the tear strength, elongation at break, and Shore A hardness for a
flexible article prepared in an LS system using a block copolymer,
i.e., a polybutylene phthalate-long chain polyalkylurethane glycol
block copolymer, as the polymeric build material, prior to and
after infiltration using the liquid infiltrant of Example 1. In the
infiltration process, the article was dipped into the liquid
infiltrant of Example 1 two times for a time period of 30 seconds
each, followed by drying after each dipping at 60.degree. C. for 45
minutes in an oven.
[0061] The infiltrated article was fully infiltrated. The tear
strength test was performed using ASTM Method D 638. TABLE-US-00002
% Infiltrant of Laser (W) Wt of Infiltrant Infiltrant the
Infiltrated Part 15 1.3 g Example 1 16.67% 13 1.4 g Example 1
18.67% 11 1.6 g Example 1 21.92% 9 1.6 g Example 1 22.22% 7 2.2 g
Example 1 30.99% 5 2.3 g Example 1 33.82% Elonga- Uninfiltrated
Infiltrated with Example 1 Elonga- tion Part Elonga- Weight (g)
Elonga- tion Shore Laser Weight tion (Part and tion Delta Delta (W)
(g) Shore (%) Infiltrant) Shore (%) % % 15 6.5 76 306 7.8 78 314
2.61 2.63 13 6.1 72 256 7.5 77 292 14.06 6.94 11 5.7 66 230 7.3 74
262 13.91 12.12 9 5.6 64 196 7.2 69 238 21.43 7.81 7 4.9 60 176 7.1
66 194 10.23 10.00 5 4.5 44 136 6.8 55 158 16.18 25.00 Tear
Strength Uninfiltrated Infiltrated Laser (W) mm.sup.2 N/mm.sup.2 N
mm.sup.2 N/mm.sup.2 N 15 40.00 4.46 178 40.65 4.42 180 13 40.15
3.59 144 40.17 3.85 155 11 39.08 3.03 118 39.74 3.17 126 9 40.15
2.27 91 40.45 2.45 99 7 39.75 1.72 68 39.89 1.88 75 5 39.00 1.09 43
39.24 1.32 52
[0062] In the above table, as the laser power increases (i.e., as W
increases), the article manufactured by an LS process has a lower
porosity, and consequently is a harder article (i.e., the Shore
hardness increases). Therefore, less liquid infiltrant is necessary
to infiltrate an article preparing using 15 W (i.e., 16.67% of the
infiltrated article is infiltrant) compared to an article prepared
using 5 W (i.e., 33.82% infiltrant).
[0063] The table also shows that infiltrating a porous article
(e.g., using a low wattage) substantially increases the mechanical
properties of the article, i.e., a substantially increased Shore
hardness, elongation at break, and tear strength. Articles
manufactured in an LS process using a high wattage also show an
increase in mechanical properties, but the percent improvement is
less because less infiltrant is required to infiltrate the harder
article.
[0064] The table further shows that the amount of infiltrate of a
fully infiltrated article varies with the laser power used in the
LS process. The amount of infiltrate of a full infiltrated article
also varies with the identity of the article. In general, a fully
infiltrated article, after drying, contains up to about 50% of the
infiltrant, by total weight of the infiltrated article. Preferably,
the fully infiltrated article, after drying, contains about 10% to
about 40%, and more preferably about 15% to about 35%, of the
infiltrant, based on the total weight of the infiltrated
article.
* * * * *