U.S. patent application number 11/521693 was filed with the patent office on 2007-03-15 for fabric pretreatment for inkjet printing.
Invention is credited to Scott W. Ellis.
Application Number | 20070056118 11/521693 |
Document ID | / |
Family ID | 37636511 |
Filed Date | 2007-03-15 |
United States Patent
Application |
20070056118 |
Kind Code |
A1 |
Ellis; Scott W. |
March 15, 2007 |
Fabric pretreatment for inkjet printing
Abstract
This invention pertains to inkjet printing on fabric and to a
pretreatment solution for the fabric that allows high quality
printing thereon. The preferred digitally printed inks are
pigmented inks.
Inventors: |
Ellis; Scott W.;
(Wilmington, DE) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY;LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1128
4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
37636511 |
Appl. No.: |
11/521693 |
Filed: |
September 15, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60717439 |
Sep 15, 2005 |
|
|
|
Current U.S.
Class: |
8/115.51 |
Current CPC
Class: |
D06P 5/30 20130101; D06P
1/67341 20130101; D06P 1/002 20130101; D06P 3/60 20130101; C09D
11/322 20130101; D06P 1/67333 20130101; C09D 11/54 20130101; B41M
5/0017 20130101 |
Class at
Publication: |
008/115.51 |
International
Class: |
C11D 3/00 20060101
C11D003/00 |
Claims
1. A method of digitally printing a textile comprising the steps
of: (a) pretreating the textile with a pretreatment solution
comprising an aqueous multivalent cationic salt solution, (b)
drying the pretreated textile, (c) digitally printing the dried,
pretreated textile with a pigmented ink jet ink.
2. The method of claim 1, wherein the multivalent cation is
selected from one or more of the group of multivalent cations of
elements Mg, Ca, Sr, Ba, Sc, Y, La, Ti, Zr, V, Cr, Mn, Fe, Ru, Co,
Rh, Ni, Pd, Pt, Cu, Au, Zn, Al, Ga, In, Sb, Bi, Ge, Sn and Pb.
3. The method of claim 1, wherein the multivalent cation is
calcium.
4. The method of claim 3, wherein the pretreatment solution
comprises a solution of a multivalent cationic salt in water,
wherein the multivalent cationic salt is selected from the group
consisting of calcium nitrate, calcium nitrate hydrate and mixtures
thereof.
5. The method of any one or combination of claims 1-4, wherein the
textile is pretreated with the pretreatment solution in a wet
pick-up of from about 0.20 to about 7.5 grams of multivalent
cationic salt per 100 grams of fabric.
6. The method of any one or combination of claims 1-5, wherein the
pigmented inkjet ink is a white pigmented inkjet ink.
7. The method of claim 6, wherein the textile is a colored textile,
and the white pigmented inkjet ink is printed onto the colored
textile as a background for an image.
8. The method of claim 7, wherein the textile is printed with the
white pigmented ink to an ink coverage of between about 5 to about
100 grams of ink per square meter of textile.
9. The method of any one or combination of claims 1-5, wherein the
textile is printed with a pigmented inkjet ink set comprises at
least two differently colored pigmented inkjet inks.
10. The method of claim 9, wherein at least one of the pigmented
inkjet inks is white.
11. The method of claim 9, wherein the ink set comprises at least
three differently colored pigmented inkjet inks, wherein at least
one is a cyan pigmented inkjet ink, at least one is a magenta
pigmented inkjet ink, and at least one is a yellow pigmented inkjet
ink.
12. The method of claim 9 or claim 10, wherein the ink set further
comprises a black pigmented inkjet ink.
13. The method of any one or combination of claims 9-12, wherein
the textile is printed with the at least two differently colored
inkjet ink to an ink coverage of between about 5 to about 17 grams
of ink per square meter of fabric.
14. The method of any one or combination of the preceding claims,
wherein the pigmented inkjet ink comprises, or each the pigmented
inkjet inks in the inkjet set individually comprise, an anionically
stabilized pigment in an aqueous vehicle.
15. The method of any one or combination of the preceding claims,
further comprising the step of post-treating the printed textile
with heat and/or pressure.
16. The method of any one or combination of the preceding claims,
wherein the textile is a T-shirt.
17. A pretreated fabric substrate comprising a fabric substrate
having applied thereon a pretreatment solution comprises a solution
of a multivalent cationic salt in water, wherein the multivalent
cationic salt is selected from the group consisting of calcium
nitrate, calcium nitrate hydrate and mixtures thereof, in a wet
pick-up of from about 0.20 to about 7.5 grams of calcium salt per
100 grams of fabric.
18. The pretreated fabric of claim 17, wherein the fabric comprises
a cotton or cotton blend.
19. The pretreated fabric of claim 17 or claim 18 which, subsequent
to application of the textile pretreatment solution, has been dried
to equilibrium moisture at ambient temperature.
20. The pretreated fabric of any one or combination of claims
17-19, which is a T-shirt.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. .sctn.119
from U.S. Provisional Application Ser. No. 60/717,439, filed Sep.
15, 2005.
BACKGROUND OF THE INVENTION
[0002] This invention pertains to inkjet printing on a pretreated
fabric with pigmented inkjet inks, and to a pretreatment solution
for the fabric that allows high quality printing thereon.
[0003] Digital printing methods such as inkjet printing are
becoming increasingly important for the printing of textiles and
offer a number of potential benefits over conventional printing
methods such as screen printing. Digital printing eliminates the
set up expense associated with screen preparation and can
potentially enable cost effective short run production. Inkjet
printing furthermore allows visual effects such as tonal gradients
and infinite pattern repeat sizes that cannot be practically
achieved with a screen printing process.
[0004] While digital printing provides a breadth of available
printing conditions for almost any fabric, there is often a need
for achieving a higher color on the fabric. It is an object of this
invention to enable higher color, high quality inkjet printing of
fabrics, such as cotton and cotton blends, with pigmented inkjet
inks.
SUMMARY OF THE INVENTION
[0005] In one aspect, the present invention relates to a method of
digitally printing a textile comprising the steps of:
[0006] (a) pretreating the textile with a pretreatment solution
comprising an aqueous multivalent cationic salt solution,
[0007] (b) drying the pretreated textile,
[0008] (c) digitally printing the dried, pretreated textile with a
pigmented ink jet ink.
[0009] The present invention pertains, in another aspect, to a
fabric that has been pretreated with an aqueous multivalent
cationic salt solution, wherein the multivalent cationic salt is a
calcium salt selected from the group consisting of calcium nitrate,
calcium nitrate hydrate and mixtures thereof.
[0010] These and other features and advantages of the present
invention will be more readily understood by those of ordinary
skill in the art from a reading of the following detailed
description. It is to be appreciated that certain features of the
invention which are, for clarity, described above and below in the
context of separate embodiments, may also be provided in
combination in a single embodiment. Conversely, various features of
the invention that are, for brevity, described in the context of a
single embodiment, may also be provided separately or in any
subcombination. In addition, references to in the singular may also
include the plural (for example, "a" and "an" may refer to one, or
one or more) unless the context specifically states otherwise.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Pretreatment Solution
[0011] The pretreatment solution used in the method of the present
invention is an aqueous multivalent cationic salt solution. More
preferably, the preteatment solution comprises a solution of a
multivalent cationic salt in water. Optionally, other ingredients
can be added. Ingredient percentages mentioned herein after are
weight percent based on the total weight of the final solution,
unless otherwise indicated.
Multivalent Cation
[0012] The pretreatments of this invention comprise one or more
multivalent cations. The effective amounts needed in a particular
situation can vary, and some adjustment, as provided for herein,
will generally be necessary.
[0013] "Multivalent" indicates an oxidation state of two or more
and, for an element "Z", are typically described as Z.sup.2+,
Z.sup.3+, Z.sup.4+ and so forth. For brevity, multivalent cations
may be referred to herein as Z.sup.x. The multivalent cations are
substantially soluble in the aqueous pretreatment solution and
preferably exist (in solution) in a substantially ionized state so
that they are in a form where they are free and available to
interact with textile when the textile is exposed to the
pretreatment solution.
[0014] Z.sup.x includes, but is not limited to multivalent cations
of the following elements: Mg, Ca, Sr, Ba, Sc, Y, La, Ti, Zr, V,
Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Cu, Au, Zn, Al, Ga, In, Sb, Bi,
Ge, Sn, Pb. In another embodiment, the multivalent cation comprises
at least one of Ca, Ba, Ru, Co, Zn and Ga. In yet another
embodiment, the multivalent cation comprises at least one of Ca,
Ba, Ru, Co, Zn and Ga. Preferably the multivalent cation is Ca.
[0015] Z.sup.x can be incorporated into pretreatment solution by
addition in a salt form or by addition in an alkaline form and used
as a base in the adjustment of the pretreatment solution pH.
[0016] The associated anionic material can be chosen from any
common anionic material, especially halides, nitrates and sulfates.
The anionic form is chosen so that the multivalent cation is
soluble in the aqueous pretreatment solution. The multivalent
cationic salts can be used in their hydrated form.
[0017] For Ca, the preferred multivalent cation salts are calcium
chloride, calcium nitrate, calcium nitrate hydrate and mixtures
thereof. Particularly preferred are calcium nitrate, calcium
nitrate hydrate and mixtures thereof.
[0018] Other optional ingredients in the pretreatment solution may
include, but are not limited to, humectants and biocides. Biocides
prevent microbial degradation--their selection and use is generally
well known in the art. Suitable humectants are the same as those
suitable for use in pigmented inkjet inks, as discussed in further
detail below.
[0019] The balance of the pretreatment solution is water. A
pretreatment solution consisting essentially of a solution of a
multivalent cationic salt in water is particularly suitable.
[0020] The solution should comprise sufficient multivalent cation
content and other ingredients to provide adequate infusion and/or
coating of the textile with the multivalent cation. Typically, the
pretreatment will comprise at least about 0.5 wt % of the
multivalent cation salt, and amounts can be used up to the
solubility limits of the particularly multivalent cation salt or
salts utilized. Preferably, the pretreatment will comprise from
about 1.0 wt % to about 30 wt % of the multivalent cation salt.
Fabric
[0021] The fabric to be pretreated can be any fabric suitable for
printing with pigmented inkjet inks, and is preferably a fabric
comprising cotton and/or cotton blends.
Pretreatment of the Fabric
[0022] Application of the pretreatment to the fabric can be any
convenient method and such methods are generally well-known in the
art. One example is an application method referred to as padding.
In padding, a fabric is dipped in the pretreatment solution, then
the saturated fabric is passed through nip rollers that squeeze out
the excess solution. The amount of solution retained in the fabric
can be regulated by the nip pressure applied by the rollers. Other
pretreatment techniques include spray application wherein the
solution is applied by spraying on the face or face and back of the
fabric. Spraying can be limited to the digitally printed area of
the printed fabric. An example of where this limited spraying would
be particularly applicable is in the digital printing of an image
on preformed textile articles such as, for example, a T-shirts,
caps, undergarments and like clothing articles.
[0023] Preferably, the pretreatment solution is applied to the
fabric in a wet pick-up of from about 0.20 to about 7.5 grams of
multivalent cationic (calcium) salt per 100 grams of fabric, more
preferably from about 0.60 to about 6.0 grams of multivalent
cationic (calcium) salt per 100 grams of fabric, and still more
preferably from about 0.75 to about 5.0 grams of multivalent
cationic (calcium) salt per 100 grams of fabric.
[0024] After application of pretreatment, the fabric may be dried
in any convenient manner. The fabric is preferably substantially
dry at the time of printing, such that the final percent moisture
is (approximately) equal to the equilibrium moisture of the
pretreated fabric at ambient temperature. The absolute amount of
moisture in the fabric, of course, can vary somewhat depending on
the relative humidity of the surrounding air.
[0025] The multivalent salts remaining in the fabric after drying
provide an interactive material that will interact with the inkjet
inks during printing. It will be appreciated that sufficient
multivalent salts must be present to effect a brighter/more
colorful image. Routine optimization will reveal appropriate
multivalent salt levels for a given printer and pigmented ink or
ink set.
Pigmented Inkjet Inks
[0026] Pigmented inkjet inks suitable for use in the present method
typically comprise a pigment dispersed in a vehicle. The vehicle
can be aqueous or non-aqueous, but aqueous vehicles are preferred.
Preferably, the pigment ink comprises an anionically stabilized
pigment dispersed in an aqueous vehicle.
[0027] An "aqueous vehicle" refers to a vehicle comprised of water
or a mixture of water and at least one water-soluble organic
solvent (co-solvent) or humectant. Selection of a suitable mixture
depends on requirements of the specific application, such as
desired surface tension and viscosity, the selected colorant, and
compatibility with substrate onto which the ink will be
printed.
[0028] Examples of water-soluble organic solvents and humectants
include: alcohols, ketones, keto-alcohols, ethers and others, such
as thiodiglycol, sulfolane, 2-pyrrolidone,
1,3-dimethyl-2-imidazolidinone and caprolactam; glycols such as
ethylene glycol, diethylene glycol, triethylene glycol,
tetraethylene glycol, propylene glycol, dipropylene glycol,
tripropylene glycol, trimethylene glycol, butylene glycol and
hexylene glycol; addition polymers of oxyethylene or oxypropylene
such as polyethylene glycol, polypropylene glycol and the like;
triols such as glycerol and 1,2,6-hexanetriol; lower alkyl ethers
of polyhydric alcohols, such as ethylene glycol monomethyl ether,
ethylene glycol monoethyl ether, diethylene glycol monomethyl,
diethylene glycol monoethyl ether; lower dialkyl ethers of
polyhydric alcohols, such as diethylene glycol dimethyl or diethyl
ether; urea and substituted ureas.
[0029] An aqueous vehicle will typically contain about 30% to about
95% water with the balance (i.e., about 70% to about 5%) being the
water-soluble solvent. Ink compositions typically contain about 60%
to about 95% water, based on the total weight of the aqueous
vehicle.
[0030] Pigments suitable for being used with the multivalent
pretreatment of the textile are those generally well-known in the
art for aqueous inkjet inks. Traditionally, pigments are stabilized
by dispersing agents, such as polymeric dispersants or surfactants,
to produce a stable dispersion of the pigment in the vehicle. More
recently though, so-called "self-dispersible" or "self-dispersing"
pigments (hereafter "SDP") have been developed. As the name would
imply, SDPs are dispersible in water without dispersants. Dispersed
dyes are also considered pigments as they are insoluble in the
aqueous inks used herein.
[0031] The dispersant or surface treatment applied to the pigment
creates an anionic surface charge ("anionic pigment dispersion").
Preferably, that surface charge is imparted predominately by
ionizable carboxylic acid (carboxylate) groups.
[0032] The pigments which are stabilized by added dispersing agents
may be prepared by methods known in the art. It is generally
desirable to make the stabilized pigment in a concentrated form.
The stabilized pigment is first prepared by premixing the selected
pigment(s) and polymeric dispersant(s) in an aqueous carrier medium
(such as water and, optionally, a water-miscible solvent), and then
dispersing or deflocculating the pigment. The dispersing step may
be accomplished in a 2-roll mill, media mill, a horizontal mini
mill, a ball mill, an attritor, or by passing the mixture through a
plurality of nozzles within a liquid jet interaction chamber at a
liquid pressure of at least 5,000 psi to produce a uniform
dispersion of the pigment particles in the aqueous carrier medium
(microfluidizer). Alternatively, the concentrates may be prepared
by dry milling the polymeric dispersant and the pigment under
pressure. The media for the media mill is chosen from commonly
available media, including zirconia, YTZ and nylon. These various
dispersion processes are in a general sense well known in the art,
as exemplified by U.S. Pat. No. 5,022,592, U.S. Pat. No. 5,026,427,
U.S. Pat. No. 5,310,778, U.S. Pat. No. 5,891,231, U.S. Pat. No.
5,976,232 and US20030089277. The disclosures of each of these
publications are incorporated by reference herein for all purposes
as if fully set forth. Preferred are 2-roll mill, media mill, and
by passing the mixture through a plurality of nozzles within a
liquid jet interaction chamber at a liquid pressure of at least
5,000 psi.
[0033] After the milling process is complete the pigment
concentrate may be "let down" into an aqueous system. "Let down"
refers to the dilution of the concentrate with mixing or
dispersing, the intensity of the mixing/dispersing normally being
determined by trial and error using routine methodology, and often
being dependent on the combination of the polymeric dispersant,
solvent and pigment.
[0034] The dispersant used to stabilize the pigment is preferably a
polymeric dispersant. Either structured or random polymers may be
used, although structured polymers are preferred for use as
dispersants for reasons well known in the art. The term "structured
polymer" means polymers having a block, branched or graft
structure. Examples of structured polymers include AB or BAB block
copolymers such as disclosed in U.S. Pat. No. 5,085,698; ABC block
copolymers such as disclosed in EP-A-0556649; and graft polymers
such as disclosed in U.S. Pat. No. 5,231,131. Other polymeric
dispersants that can be used are described, for example, in U.S.
Pat. No. 6,117,921, U.S. Pat. No. 6,262,152, U.S. Pat. No.
6,306,994 and U.S. Pat. No. 6,433,117. The disclosure of each of
these publications is incorporated herein by reference for all
purposes as if fully set forth.
[0035] Polymer dispersants suitable for use in the present
invention comprise both hydrophobic and hydrophilic monomers. Some
examples of hydrophobic monomers used in random polymers are methyl
methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate,
benzyl methacrylate, 2-phenylethyl methacrylate and the
corresponding acrylates. Examples of hydrophilic monomers are
methacrylic acid, acrylic acid, dimethylaminoethyl(meth)acrylate
and salts thereof. Also quaternary salts of
dimethylaminoethyl(meth)acrylate may be employed.
[0036] A wide variety of organic and inorganic pigments, alone or
in combination, may be selected to make the ink. The term "pigment"
as used herein means an insoluble colorant. The pigment particles
are sufficiently small to permit free flow of the ink through the
inkjet printing device, especially at the ejecting nozzles that
usually have a diameter ranging from about 10 micron to about 50
micron. The particle size also has an influence on the pigment
dispersion stability, which is critical throughout the life of the
ink. Brownian motion of minute particles will help prevent the
particles from flocculation. It is also desirable to use small
particles for maximum color strength and gloss. The range of useful
particle size is typically about 0.005 micron to about 15 micron.
Preferably, the pigment particle size should range from about 0.005
to about 5 micron and, most preferably, from about 0.005 to about 1
micron. The average particle size as measured by dynamic light
scattering is less than about 500 nm, preferably less than about
300 nm.
[0037] The selected pigment(s) may be used in dry or wet form. For
example, pigments are usually manufactured in aqueous media and the
resulting pigment is obtained as water-wet presscake. In presscake
form, the pigment is not agglomerated to the extent that it is in
dry form. Thus, pigments in water-wet presscake form do not require
as much deflocculation in the process of preparing the inks as
pigments in dry form. Representative commercial dry pigments are
listed in previously incorporated U.S. Pat. No. 5,085,698.
[0038] In the case of organic pigments, the ink may contain up to
approximately 30%, preferably about 0.1 to about 25%, and more
preferably about 0.25 to about 10%, pigment by weight based on the
total ink weight. If an inorganic pigment is selected, the ink will
tend to contain higher weight percentages of pigment than with
comparable inks employing organic pigment, and may be as high as
about 75% in some cases, since inorganic pigments generally have
higher specific gravities than organic pigments.
[0039] Self-dispersed pigments can be used and are often
advantageous over traditional dispersant stabilized pigments from
the standpoint of greater stability and lower viscosity at the same
pigment loading. This can provide greater formulation latitude in
final ink.
[0040] SDPs, and particularly self-dispersing carbon black
pigments, are disclosed in, for example, U.S. Pat. No. 2,439,442,
U.S. Pat. No. 3,023,118, U.S. Pat. No. 3,279,935 and U.S. Pat. No.
3,347,632. Additional disclosures of SDPs, methods of making SDPs
and/or aqueous inkjet inks formulated with SDP's can be found in,
for example, U.S. Pat. No. 5,554,739, U.S. Pat. No. 5,571,311, U.S.
Pat. No. 5,609,671, U.S. Pat. No. 5,672,198, U.S. Pat. No.
5,698,016, U.S. Pat. No. 5,707,432, U.S. Pat. No. 5,718,746, U.S.
Pat. No. 5,747,562, U.S. Pat. No. 5,749,950, U.S. Pat. No.
5,803,959, U.S. Pat. No. 5,837,045, U.S. Pat. No. ,5,846,307, U.S.
Pat. No. 5,851,280, U.S. Pat. No. 5,861,447, U.S. Pat. No.
5,885,335, U.S. Pat. No. 5,895,522, U.S. Pat. No. 5,922,118, U.S.
Pat. No. 5,928,419, U.S. Pat. No. 5,976,233, U.S. Pat. No.
6,057,384, U.S. Pat. No. 6,099,632, U.S. Pat. No. 6,123,759, U.S.
Pat. No. 6,153,001, U.S. Pat. No. ,6,221,141, U.S. Pat. No.
6,221,142, U.S. Pat. No. 6,221,143, U.S. Pat. No. 6,281,267, U.S.
Pat. No. 6,329,446, US2001/0035110, EP-A-1114851, EP-A-1158030,
WO01/10963, WO01/25340 and WO01/94476.
[0041] Titanium dioxide is also an example of a pigment that can be
used, and is potentially advantageous because it is white in color.
Titanium dioxide can be difficult to disperse in an ink vehicle
that is compatible with an ink jet printer system. Those
dispersions and/or ink vehicles that provide inkjet stable titanium
dioxide can be used with the multivalent cation pretreated
textile.
[0042] In a preferred embodiment, a combination of a graft and
block copolymers are used as co-dispersants for the titanium
dioxide pigment, such as described in U.S. application Ser. No.
10/872,856 (filed Jun. 21, 2004), the disclosure of which is
incorporated by reference herein for all purposes as if fully set
forth. This combination of dispersants is effective in stabilizing
titanium dioxide pigment slurries and, furthermore, provides
enhanced stability in the ink formulations. Other preferred
titanium dioxide ink jet inks are described in commonly owned US
Provisional Appln. Ser. No. 60/717,483, entitled "Aqueous Inkjet
Ink" (Internal Reference # IJ0132 USPRV) and filed concurrently
herewith, the disclosure of which is incorporated by reference
herein for all purposes as if fully set forth.
Additives
[0043] Other ingredients (additives) may be formulated into the
inkjet ink, to the extent that such other ingredients do not
interfere with the stability and jetablity of the finished ink,
which may be readily determined by routine experimentation. Such
other ingredients are in a general sense well known in the art.
[0044] Commonly, surfactants are added to the ink to adjust surface
tension and wetting properties. Suitable surfactants include
ethoxylated acetylene diols (e.g. Surfynols.RTM. series from Air
Products), ethoxylated primary (e.g. Neodol.RTM. series from Shell
and Tomadol.RTM. series from Tomah Products) and secondary (e.g.
Tergitol.RTM. series from Union Carbide) alcohols, sulfosuccinates
(e.g. Aerosol(.RTM. series from Cytec), organosilicones (e.g.
Silwet.RTM. series from GE Silicons) and fluoro surfactants (e.g.
Zonyl.RTM. series from DuPont). Surfactants are typically used in
the amount of about 0.01 to about 5% and preferably about 0.2 to
about 2%, based on the total weight of the ink.
[0045] Polymers may be added to the ink to improve durability. The
polymers can be soluble in the vehicle or dispersed (e.g. "emulsion
polymer" or "latex"), and can be ionic or nonionic. Useful classes
of polymers include acrylics, styrene-acrylics and polyurethanes. A
particularly preferred binder additive is a crosslinked
polyurethane as described in US20050182154, the disclosure of which
is incorporated by reference herein for all purposes as if fully
set forth.
[0046] Biocides may be used to inhibit growth of microorganisms.
Buffers may be used to maintain pH. Buffers include, for example,
tris(hydroxymethyl)-aminomethane ("Trizma" or "Tris").
[0047] Inclusion of sequestering (or chelating) agents such as
ethylenediaminetetraacetic acid (EDTA), iminodiacetic acid (IDA),
ethylenediamine-di(o-hydroxyphenylacetic acid) (EDDHA),
nitrilotriacetic acid (NTA), dihydroxyethylglycine (DHEG),
trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA),
dethylenetriamine-N,N,N',N'', N''-pentaacetic acid (DTPA), and
glycoletherdiamine-N,N,N',N'-tetraacetic acid (GEDTA), and salts
thereof, may be advantageous, for example, to eliminate deleterious
effects of heavy metal impurities.
[0048] The components described above can be combined to make an
ink in various proportions and combinations in order to achieve
desired ink properties, as generally described above, and as
generally recognized by those of ordinary skill in the art. Some
experimentation may be necessary to optimize inks for a particular
end use, but such optimization is generally within the ordinary
skill in the art.
[0049] The amount of vehicle in an ink is typically in the range of
about 70% to about 99.8%, and more typically about 80% to about
99%. Colorant is generally present in amounts up to about 10%.
Percentages are weight percent of the total weight of ink.
[0050] Other ingredients (additives), when present, generally
comprise less than about 15% by weight, based on the total weight
of the ink. Surfactants, when added, are generally in the range of
about 0.2 to about 3% by weight based on the total weight of the
ink. Polymers can be added as needed, but will generally be less
than about 15% by weight based on the total weight of the ink.
[0051] Drop velocity, separation length of the droplets, drop size
and stream stability are greatly affected by the surface tension
and the viscosity of the ink. Ink jet inks typically have a surface
tension in the range of about 20 dyne/cm to about 70 dyne/cm at
25.degree. C. Viscosity can be as high as 30 cP at 25.degree. C.,
but is typically somewhat lower. The ink has physical properties
are adjusted to the ejecting conditions and printhead design. The
inks should have excellent storage stability for long periods so as
not clog to a significant extent in an ink jet apparatus. Further,
the ink should not corrode parts of the ink jet printing device it
comes in contact with, and it should be essentially odorless and
non-toxic. Preferred pH for the ink is in the range of from about
6.5 to about 8.
Ink Sets
[0052] The term "ink set" refers to all the individual inks or
other fluids an inkjet printer is equipped to jet.
[0053] In one preferred embodiment, the ink set comprises at least
two differently colored pigmented inkjet inks, at least one of
which is a white pigmented inkjet ink as described above.
[0054] In another preferred embodiment, the ink set comprises at
least three differently colored pigmented inkjet inks, wherein at
least one is a cyan pigmented inkjet ink, at least one is a magenta
pigmented inkjet ink, and at least one is a yellow pigmented inkjet
ink.
[0055] In addition to the colored inkjet inks just mentioned, it is
also preferable to include a black pigmented inkjet ink in the ink
set.
[0056] In addition to the CMYKW inks mentioned above, the ink sets
may contain additional differently colored inks, as well as
different strength versions of the CMYKW and other inks.
[0057] For example, the inks sets of the present invention can
comprise full-strength versions of one or more of the inks in the
ink set, as well as "light" versions thereof.
[0058] Additional colors for the inkjet ink set include, for
example, orange, violet, green, red and/or blue.
Printing Method
[0059] The present method relates to digitally printing a
pretreated textile substrate. Typically, this involves the
following steps:
[0060] (1) providing an inkjet printer that is responsive to
digital data signals;
[0061] (2) loading the printer with the textile substrate to be
printed, in this case the pretreated textile substrate;
[0062] (3) loading the printer with the above-mentioned inks or
inkjet ink sets; and
[0063] (4) printing onto the substrate using the inkjet ink or
inkjet ink set in response to the digital data signals.
[0064] Printing can be accomplished by any inkjet printer equipped
for handling and printing fabric. Commercial printers include, for
example, the Dupont.RTM. Artistri.RTM. 3210 and 2020 printers, and
the Mimaki TX series of printers.
[0065] As indicated above, a variety of inks and ink sets are
available for use with these printers. Commercially available ink
sets include, for example, DuPont.RTM. Artistri.RTM. P700 and P5000
series inks.
[0066] The amount of ink laid down on the fabric can vary by
printer model, by print mode (resolution) within a given printer
and by the percent coverage need to achieve a given color. The
combined effect of all these considerations is grams of ink per
unit area of fabric for each color. In one embodiment, ink coverage
is preferably from about 5 to about 17 grams of ink per square
meter of fabric for colored inks (including black and white
inks).
[0067] If, however, a white ink is used as a background for the
digitally printed image, up to about six times more white ink
(generally from about 5 to about 100 grams of ink per square meter
of fabric) may be used to obtain an enhanced final image. In such
case, the white ink is initially printed onto the substrate in at
least a portion of the area to be covered by the final image (the
underprint portion), then the final image is printed at least over
the underprint portion.
[0068] The white ink can also be printed outside the boundaries of
the final image (either as part of the initial background printing
or subsequently as part of the image printing), for example, to
generate a small, imperceptible boundary to the image, making the
image appear to have a distinct boundary.
[0069] The use of the white ink for printing a background for an
image is particularly useful when printed onto colored (non-white)
textiles.
Post Treatment of Fabric
[0070] Fabric printed with pigmented inks will typically be
post-treated according to procedures well-known in the textile
printing art.
[0071] The printed textiles may optionally be post processed with
heat and/or pressure, such as disclosed in US20030160851 (the
disclosure of which is incorporated by reference herein for all
purposes as if fully set forth). Upper temperature is dictated by
the tolerance of the particular textile being printed. Lower
temperature is determined by the amount of heat needed to achieve
the desired level of durability. Generally, fusion temperatures
will be at least about 80.degree. C. and preferably at least about
140.degree. C., more preferably at least about 160.degree. C. and
most preferably at least about 180.degree. C.
[0072] Fusion pressures required to achieve improved durability can
be very modest. Thus, pressures can be about 3 psig, preferably at
least about 5 psig, more preferrable at least about 8 psig and most
preferably at least about 10 psig. Fusion pressures of about 30 psi
and above seem to provide no additional benefit to durability, but
such pressures are not excluded.
[0073] The duration of fusion (amount of time the printed textile
is under pressure at the desired temperature) is not believed to be
particularly critical. Most of the time in the fusion operation
generally involves bringing the print up to the desired
temperature. Once the print is fully up to temperature, the time
under pressure can be brief (seconds).
EXAMPLES
Printing Conditions
[0074] The examples described below were done using an Epson 3000
ink jet printer, a Fast T-Jet.TM. from US Screen Printing Institute
(Tempe, Ariz.), the and prints were made on various substrates. The
textile substrates used were Hanes Beefy T 100% cotton t-shirts,
Hanes Heavy weight 100% cotton t-shirts, Hanes 50/50 polycotton
cotton t-shirts, and a black fabric from Joann's Fabric (woven 100%
cotton tweed). All test prints were fused at about 170.degree. C.
for about 1 minute.
[0075] Colorimetric measurements were done using a Minolta
Spectrophotometer CM-3600d using Spectra Match software.
[0076] Where indicated the printed textile was tested for
washfastness according to methods developed by the American
Association of Textile Chemists and Colorists, (AATCC), Research
Triangle Park, N.C. The AATCC Test Method 61-1996, "Colorfastness
to Laundering, Home and Commercial: Accelerated", was used. In that
test, colorfastness is described as "the resistance of a material
to change in any of its color characteristics, to transfer of its
colorant(s) to adjacent materials or both as a result of the
exposure of the material to any environment that might be
encountered during the processing, testing, storage or use of the
material." Tests 2A and 3A were done and the color washfastness and
stain rating were recorded. The ratings for these tests are from
1-5 with 5 being the best result, that is, little or no loss of
color and little or no transfer of color to another material,
respectively.
Pretreatment Solutions
[0077] Reagent grade calcium nitrate tetrahydrate (Aldrich) was
mixed with deionized water until the calcium nitrate was completely
in solution. Four pretreatment solutions were prepared, and a
comparative solution without a multivalent cation present was also
prepared. TABLE-US-00001 TABLE 1 Pretreatment Solutions 1-4
Component (Wt %) as Calcium Nitrate as Calcium Tetrahydrate Nitrate
Pretreatment Solution 1 2 1.39 Pretreatment Solution 2 5 3.47
Pretreatment Solution 3 10 6.95 Pretreatment Solution 4 20 13.9
Comparative Solution 0.0 0.0
Pigmented Inks
[0078] Pigmented Inks were used for testing the multivalent
pretreatment solution.
[0079] Ink Example 1 has the following formulation shown in Table
1. This ink is a white ink that can be printed prior to printing
other pigmented ink or at the same time. TABLE-US-00002 TABLE 1 Ink
Example 1 Wt % (based on total Component Source weight of Ink)
Titanium Dioxide Slurry R-746 10.0 (solids) Polymeric Binder
Crosslinked 8.0 polyurethane (solids) PUD EX2 in US20050182154
Surfactant Byk-348 0.25 (BykChemie) Solvent Ethylene 25.0 Glycol
Solvent Glycerol 12.0 Biocide Proxel .RTM. GXL 0.2 (Avecia) Water
Bal. to 100%
[0080] R-746 is a commercially available titanium dioxide
dispersion (E.I. DuPont de Nemours, Wilmington Del.), which is
described as a 76.5 wt % (solids) titanium dioxide slurry with a
hydrophilic acrylic copolymer as the dispersant. The titanium
dioxide used in this slurry is described as being coated with 3%
hydrous silica and 1.5-2.0% hydrous alumina, with a mean particle
size of about 280 nm.
[0081] Where all of the weights are the net weights in the ink. For
example, the polymeric binder is available as an emulsion in about
a 33% weight percent solution in water. Thus about 24 grams of the
polymeric binder emulsion is added to the ink formulation so that
8% polymeric binder is in the final ink.
[0082] Ink example 2 is a magenta ink and is based on pigment R122.
The formulation is listed in Table 2. TABLE-US-00003 TABLE 2
Magenta Ink Formulation Component Wt % R122 Glycerol 15.00 Ethylene
Glycol 8.00 Dowanol .RTM. DPM (Dow Chemical) 3.00 Surfynol .RTM.
440 1.25 2-Pyrrolidone Proxel .RTM. GXL (Avecia) 0.10 Polymeric
Binder 7.00 (solids) Water Bal. to 100%
[0083] The polymeric binder was a crosslinked polyurethane (PUD
EX2) in previously incorporated US20050182154.
Printing Performance
[0084] Ink Example 1 was printed with and without Pretreatment
Solution 4. The Pretreatment solution was sprayed on the T-shirt in
an area about the same as the intended image to be printed. The
estimated amount of calcium nitrate on the T-shirt prior to
printing was about 5 grams/square meter.
[0085] The printing was done using a Fast T-Jet.RTM. from US Screen
Printing Institute with a Huffy beefy T-shirt that was used as a
dark black T-shirt. The white ink of Ink Example 1 was printed out
of three of the seven used printing channels (replacing the light
cyan, light magenta and light black), and DuPont.RTM. Artistri.RTM.
P5000 CMYK inks were printed out of the other four channels. The
image printed was a picture of racing airplanes at the Reno races.
The image had an area of a bright red and white nosecone. The color
at these two spots was measured. Table 3 shows colorimetric
measurements. TABLE-US-00004 TABLE 3 Colorimetric Measurement for
Ink Example 1; Black T-shirt Name L* a* b* C* h.degree. OD K/S 1
black t-shirt 16.3627 0.2819 -1.1899 1.2228 283.327 1.721246
25.3253 2 red nose cone control, 19.1147 1.4444 0.5092 1.5315
19.4208 1.609065 19.3375 no pretreatment, no white ink background 3
red nose cone, no 21.4612 1.9184 1.5157 2.4449 38.3126 1.543634
16.4968 pretreatment, white ink background 4 red nose cone, 28.2834
7.7313 7.3719 10.6826 43.6368 1.411168 11.906 pretreatment, no
white ink background 5 red nose cone, 40.043 24.4182 18.2712
30.4973 36.8061 1.304518 9.1054 pretreatment and white ink
background 6 white nose cone, no 23.9974 -0.924 -3.9734 4.0794
256.908 1.458421 13.3852 pretreatment, no white background 7 white
nose cone, no 28.0427 -1.3172 -4.7087 4.8894 254.372 1.341035
9.9877 pretreatment, with white ink background 8 white nose cone,
70.3828 -3.1101 -1.3964 3.4092 204.179 0.613144 1.1736
pretreatment, no white ink background 9 white nose cone, 77.6686
-2.4575 -2.3914 3.429 224.219 0.538501 0.8724 pretreatment, with
white ink background
[0086] Entry 1 was the colorimetric measurement of the unprinted
T-shirt. Entries 4, 5, 8 and 9 are inventive in that they show the
effect of the pretreatment. Entries 2,3, 6 and 7 show the print
performance without the pretreatment with the multivalent salt.
Significantly, enhanced colors are observed when the pretreatment
was used.
[0087] The t-shirt of entry 9 was subject to several cycles of
laundering and it was observed that the image did not fade with the
washings.
[0088] A similar test was done using a white T-shirt shown in Table
4. The T-shirt was pretreated by spraying a Pretreatment Solution 4
and printed using the Fast T-Jet.RTM. US Screen Printing Institute.
TABLE-US-00005 TABLE 4 Colorimetric Measurement for Ink Example 1;
White T-shirt Name L* a* b* C* h.degree. OD K/S White T-shirt 95.18
3.36 -13.87 14.28 283.62 0.68 1.50 red nose cone 53.18 29.26 23.47
37.51 38.73 1.13 5.72 White nose cone 78.79 -1.58 -1.17 1.97 216.42
0.70 1.62
[0089] Another test was done using the Epson 3000 printer and Black
100% woven cotton tweed. The cotton was pretreated with
Pretreatment Solution 4. Ink Example 1 was printed using 4 passes
and the DuPont.RTM. Artistri.RTM. P5000 CK inks in one pass. Blocks
of colors were printed and the color properties measured and the
results are shown in Table 5. TABLE-US-00006 TABLE 5 Colorimetric
Measurements for Ink Example 1; Black Cotton 3A Wash L* a b C
H.degree. OD A05 K 28.8139 -0.1573 0.1563 0.2218 135.1751 1.29 3.5
ink C 49.5002 -15.7895 -24.9692 29.5427 237.6924 1.08 4 ink
[0090] For comparison, K ink was printed on a 419 cotton and the OD
was 1.17 and the wash fastness was 3. For comparison, C ink was
printed on a 419 white cotton and the OD was 1.13 and the wash
fastness was 3. The combination of the pretreatment, the white ink
and the pigmented DuPont.RTM. Artistri.RTM. P5000 CK results in
superior color and wash fastness.
[0091] Pretreatment Solutions 1-4 and the Comparative Solution were
tested with Ink Example 1. The results are shown in Table 6.
TABLE-US-00007 TABLE 6 Pretreatment Solutions 1-4; Print
Performance L* a* b* C* h.degree. Refl. OD K/S Pretreatment 57.38
-2.74 -4.77 5.50 240.17 18.29 0.74 1.83 Sol 1 Pretreatment 64.28
-2.57 -5.22 5.82 243.82 22.70 0.64 1.32 Sol 2 Pretreatment 73.82
-3.01 -3.13 4.35 226.11 27.19 0.57 0.97 Sol 3 Pretreatment 77.67
-2.46 -2.39 3.43 224.22 28.94 0.54 0.87 Sol 4 Comparative 28.04
-1.32 -4.71 4.89 254.37 4.56 1.34 9.99 Sol 1
[0092] In this test the L* is significantly higher when
Pretreatment Solution 1 is compared to no pretreatment. The L*
improves with increase concentration of the multivalent salt in the
pretreatment solutions.
[0093] Ink Example 2 was printed with and without Pretreatment
Solution 4. TABLE-US-00008 TABLE 7 Pretreatment Solution 4 with Ink
Example 2 3A Wash- L* a b C H.degree. OD fastness Untreated cotton
55.65 42.94 11.45 44.44 345.07 0.88 3.00 treated cotton 52.08 47.90
10.38 49.02 347.77 1.02 1.40 untreated 56.13 41.08 11.67 42.71
344.14 0.86 3.00 polycotton treated polycotton 49.40 47.94 9.64
48.90 348.63 1.10 0.80 cotton: 419 available from Testfabrics, West
Pittston, PA polycotton: 7435 trom Testfabrics
[0094] The pretreatment significantly improves the OD for both the
polycotton cotton fabrics. The washfastness of this pigmented ink
is poorer with pretreatment with multivalent cations.
* * * * *