U.S. patent application number 13/999874 was filed with the patent office on 2014-09-25 for reaction-based laser marking compositions, systems and methods.
The applicant listed for this patent is Jagdip Thaker. Invention is credited to Jagdip Thaker.
Application Number | 20140287151 13/999874 |
Document ID | / |
Family ID | 45527013 |
Filed Date | 2014-09-25 |
United States Patent
Application |
20140287151 |
Kind Code |
A1 |
Thaker; Jagdip |
September 25, 2014 |
Reaction-based laser marking compositions, systems and methods
Abstract
An ink formulation comprises a binder and at least one marking
component, which comprises at least one metal oxides or oxyanion
and at least one oxidizing/reducing agent, which absorbs laser
irradiation between wavelengths of 780-10,600 nm, thereby causes
the formulation to change color.
Inventors: |
Thaker; Jagdip; (Schaumburg,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Thaker; Jagdip |
Schaumburg |
IL |
US |
|
|
Family ID: |
45527013 |
Appl. No.: |
13/999874 |
Filed: |
March 31, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13136288 |
Jul 28, 2011 |
8765855 |
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13999874 |
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Current U.S.
Class: |
427/466 ;
106/31.13; 106/31.6; 106/31.77; 106/31.78; 106/31.8; 106/31.81;
106/31.9; 427/555; 427/556 |
Current CPC
Class: |
C09D 7/61 20180101; C09D
11/14 20130101; B05D 3/06 20130101; C09D 11/037 20130101; C09D 5/26
20130101; C09D 5/32 20130101; C08K 5/0041 20130101; B05D 1/007
20130101; B41M 5/267 20130101; B05D 1/02 20130101 |
Class at
Publication: |
427/466 ;
106/31.13; 106/31.8; 106/31.81; 106/31.6; 106/31.77; 106/31.78;
106/31.9; 427/555; 427/556 |
International
Class: |
C09D 11/14 20060101
C09D011/14; B05D 1/00 20060101 B05D001/00; B05D 1/02 20060101
B05D001/02; B05D 3/06 20060101 B05D003/06 |
Claims
1. A laser marking composition comprising (I) a marking component
comprising (a) at least one metal oxide selected from vanadium
pentoxide and copper oxide, and (b) zinc phosphate; and (II)
optionally, a binder, wherein upon irradiation in a wavelength
range of between about 700 nm and 14000 nm the laser marking
composition bonds to a substrate to which it is contacted.
2. The composition of claim 1 wherein the binder comprises: i) a
resin selected from the group consisting of acrylics, acrylates,
alkyds, cellulose, cellulose derivatives, polysaccharides,
polysaccharide derivatives, rubber resins, ketones, maleics,
formaldehydes, phenolics, epoxides, fumarics, hydrocarbons,
isocyanate free polyurethanes, polyvinyl butyral, polyamides,
shellac, polyvinyl alcohol and any combination thereof; and ii) a
solvent selected from the group consisting of methylated spirits,
alkyl acetate, propanol, isopropanol, n-propyl acetate, toluene,
xylene, cyclohexanone, alkoxyethanol, butoxyethanol, aromatic
distillates having a boiling point of from about 200.degree. C. to
310.degree. C., water, and any combination thereof.
3. The composition of claim 1 further comprising one or more
additives selected from the group consisting of plasticizers, wax,
drying additives, chelating agents, antioxidants, anionic
surfactants, zwitterionic surfactants, amphoteric surfactants,
nonionic surfactants, defoamers, alkali additives, reducing agents,
lubricating agents, pigments, sensitizers, alumina, titanium oxide,
zinc oxide, kaolin, mica and any combination thereof.
4. The composition of claim 1 wherein irradiation is performed a
range of between about 700 nm and 11000 nm.
5. The composition of claim 1 further comprising a pigment
composition selected from monoazo pigments, C.I. Pigment Brown,
C.I. Pigment Orange, C.I. Pigment Red, C.I. Pigment yellow; diazo
pigments, C.I. Pigment Orange, anthanthrone pigments, anthraquinone
pigments, C.I. Pigment Violet, anthrapyrimidine pigments,
quinophthalone pigments, dioxazine pigments, flavanthrone pigments,
C.I. Pigment Blue, isoindoline pigments, isoviolanthrone pigments,
metal-complex pigments, C.I. Pigment Green; perinone pigments,
perylene pigments, C.I. Pigment Black, phthalocyanine pigments,
pyranthrone pigments, thioindigo pigments, triarylcarbonium
pigments, Aniline Black, Aldazine Yellow, C.I. Pigment Brown,
liquid crystal polymer pigments (LCP pigments) or any combination
thereof.
6. The composition of claim 1 wherein the substrate comprises
metal, ceramic, glass, porcelain, marble, natural stone, plastic,
paper, rubber, wood, cardboard or a combination thereof.
7. The composition of claim 1 wherein the substrate is selected
from the group consisting of glass, lead-free glass, ceramic tiles,
sanitary ware, stoneware, porcelain, bricks, electronic quality
ceramic substrates, marble, granite, slate, limestone, metal,
steel, brass, copper, aluminum, tin, zinc, PVC, polyamides,
polyolefins, polyethylenes, polycarbonates and
polytetrafluoroethylene.
8. A method of laser marking a substrate in a desired pattern
comprising: a) obtaining a laser ink formulation comprising the
composition of claim 1; b) contacting the formulation with a
substrate; and c) irradiating the formulation with a laser having a
wavelength of between about 700 nm and 11000 nm, thereby causing
the composition to form a semi-permanent bond to the substrate and
forming the desired pattern.
9. The method of claim 8 further comprising the step of determining
a desired pattern to be formed on the substrate.
10. The method of claim 8 wherein the step of contacting the
composition with a substrate comprises electrostatially applying a
layer of the composition onto the substrate.
11. The method of claim 8 wherein the step of contacting the
composition with a substrate comprises spraying a layer of the
composition onto the substrate.
12. The method of claim 8 wherein the pattern is selected from the
group consisting of a pattern, a bar code, an identifying code and
a name.
13. The method according to claim 8, wherein the laser is selected
from a fibre, diode, diode array or CO.sub.2 laser.
14. The method of claim 8 wherein the substrate comprises metal,
ceramic, glass, porcelain, marble, natural stone, plastic, paper,
rubber, wood, cardboard, lead-free glass, ceramic tiles, sanitary
ware, stoneware, bricks, electronic quality ceramic substrates,
granite, slate, limestone, steel, brass, copper, aluminum, tin,
zinc, PVC, polyamides, polyolefins, polyethylenes, polycarbonates,
polytetrafluoroethylene or any combination thereof.
15. The method of claim 8 wherein the composition further comprises
a pigment composition selected from monoazo pigments, C.I. Pigment
Brown, C.I. Pigment Orange, C.I. Pigment Red, C.I. Pigment yellow;
diazo pigments, C.I. Pigment Orange, anthanthrone pigments,
anthraquinone pigments, C.I. Pigment Violet, anthrapyrimidine
pigments, quinophthalone pigments, dioxazine pigments, flavanthrone
pigments, C.I. Pigment Blue, isoindoline pigments, isoviolanthrone
pigments, metal-complex pigments, C.I. Pigment Green; perinone
pigments, perylene pigments, C.I. Pigment Black, phthalocyanine
pigments, pyranthrone pigments, thioindigo pigments,
triarylcarbonium pigments, Aniline Black, Aldazine Yellow, C.I.
Pigment Brown, liquid crystal polymer pigments (LCP pigments) or
any combination thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation Application of
application Ser. No. 13/136,288, filed Jun. 28, 2011, which claims
the benefit of U.S. Provisional Application Ser. No. 61/400,407,
filed Jul. 28, 2010, herein incorporated by reference.
FIELD OF INVENTION
[0002] This invention relates to laser marking by
oxidation/reduction reactions.
BACKGROUND OF THE INVENTION
[0003] Pigments have been proposed, which can be used to mark a
substrate by the application of laser energy. Reference can be made
to WO-A-00/43456, JP-A-11001065, EP-A0522370, EP-A-0797511, U.S.
Pat. Nos. 5,053,440; 5,350,792; 5,928,780; 6,017,972; 6,019,831;
5,489,639 and 5,884,079.
[0004] WO02/01250 discloses the use of oxymetal salts in laser
marking. AOM (ammonium octamolybdate) is an example of a material
that can be marked directly with 10,600 nm laser radiation.
[0005] WO05/068207 discloses the use of NIR laser radiation (i.e.
at 800 to 2000 nm) to initiate a color change reaction when a
NIR-absorbing metal salt is used in combination with a substance
that normally undergoes a color change reaction at much longer
wavelength (about. 10,600 nm), e.g. AOM.
[0006] JP8127670 discloses the use of reduced titanium oxide
compounds for incorporation into thermoplastics, for the laser
marking of molded products.
[0007] U.S. Pat. No. 5,911,921 discloses the use of
non-stoichiometric ytterbium phosphate to produce NIR absorbing
inks, e.g. for printing stealth bar codes.
SUMMARY OF INVENTION
[0008] Described herein are compositions, systems and method
related to coating compositions which can be used in marking a
substrate, e.g., heating or laser marking. The combination of the
marking component(s) as described herein with a binder increases
the durability of the mark, rendering it permanent or
semi-permanent on a substrate or device to which it is applied. The
present invention can utilize a laser, for example a low to high
powered laser, to economically laser-mark substrates with the laser
marking composition of the present invention.
[0009] This invention is based on the discovery that certain
compounds absorb certain laser wavelengths, and in particular IR or
Near-IR laser wavelengths. When compositions or formulations
described herein are heated (using any variety of methods and in
particular laser light), it causes the formulation or composition
to stick (permanently or semi-permanently) to a material on which
it is applied to form an image or pattern. Such an image or pattern
can be formed by the localized application or irradiation with a
laser in the desired pattern after uniform coating of a substrate.
In some embodiments, the present invention utilizes a low-energy
laser, such as a diode laser, typically emitting light at a
wavelength in the range of 800 nm to 11000 nm. According to the
present invention, the potential of utilizing fibre, diode, diode
array and CO.sub.2 lasers for imaging applications on a substrate,
for example, of plastic or cardboard packaging can be realized. In
some embodiments, by the application of liquid film-forming
formulations (such as inks) onto various substrates to produce
coatings capable of distinct colors, exposure to near-IR sources
produces good results dependent primarily on the formulation of the
coated pigment powders.
[0010] The present invention will become apparent from the
following detailed description and examples, which comprises, in
one aspect is laser marking composition comprising (i) a marking
component comprising a metal oxide (the metal oxide selected from
bismuth vanadate, cobalt oxide, vanadium pentoxide, copper oxide,
chromium oxide, iron oxide, zirconium oxide, molybdenum oxide, red
iron oxide, tungsten oxide, silica or tin oxide or a combination
thereof) and an oxidizing/reducing agent (the oxidizing/reducing
agent selected from potassium permanganate, sodium permanganate,
calcium permanganate, ammonium permanganate, or other permanganate
salt, perchlorate or a percholorate salt, chromate or a chromate
salt, an inorganic peroxide, hydrogen peroxide, ionic peroxide
salts, acid peroxides, sodium perborate, perborate salts, silver
oxide, tetroxide, osmium tetroxide, fluorine, chlorine, sulfuric
acid, acid peroxides, lithium hydroxide, chromium compounds,
chromic diacids, chromium trioxide, pyridinium chlorochromate,
chromate compounds, dichromate compounds, persulfuric acids, nitric
acid, nitrate compounds, Lithium aluminium hydride, hydride salts,
Nascent (atomic) hydrogen, Sodium amalgam, Sodium borohydride,
borohydride salts, tin(II) chloride, chloride salts, Sulfite
compounds, Hydrazine, zinc-mercury amalgam Diisobutylaluminum
hydride, Lindlar catalyst, molybdenum oxide, Oxalic acid, Formic
acid, Ascorbic acid, Phosphites, hypophosphites, phosphorous acid,
phosphate, phosphate salts, zinc phosphate, copper phosphate,
ammonium phosphate, tricalcium phosphate, Dithiothreitol,
hydroquinone, isoascorbic acid, thiols, glutathione, polyphenols,
Vitamin A, iron(II) sulfate and, optionally, (ii) a binder. Upon
irradiation in a wavelength range of between about 700 nm and 14000
nm the laser marking composition bonds to a substrate to which it
is contacted.
[0011] In one embodiment, the metal oxide is selected from the
group consisting of bismuth vanadate, vanadium pentoxide, cobalt
oxide, red iron oxide, zinc phosphate, copper oxide, chromium
oxide, zirconium oxide and any combination thereof.
[0012] In one embodiment, the binder comprises: i) a resin chosen
from acrylics, acrylates, alkyds, cellulose, cellulose derivatives,
polysaccharides, polysaccharide derivatives, rubber resins,
ketones, maleics, formaldehydes, phenolics, epoxides, fumarics,
hydrocarbons, isocyanate free polyurethanes, polyvinyl butyral,
polyamides, shellac, polyvinyl alcohol or any combination thereof;
and ii) a solvent selected from methylated spirits, alkyl acetate,
propanol, isopropanol, n-propyl acetate, toluene, xylene,
cyclohexanone, alkoxyethanol, butoxyethanol, aromatic distillates
having a boiling point of from about 200.degree. C. to 310.degree.
C., water, or any combination thereof.
[0013] In one embodiment, one or more additives can be added, such
as plasticizers, wax, drying additives, chelating agents,
antioxidants, anionic surfactants, zwitterionic surfactants,
amphoteric surfactants, nonionic surfactants, defoamers, alkali
additives, reducing agents, lubricating agents, pigments,
sensitizers, alumina, titanium oxide, zinc oxide, kaolin, mica or
any combination thereof.
[0014] In another embodiment, the marking component further
comprises a pigment composition, which can be one or a combination
of monoazo pigments, C.I. Pigment Brown, C.I. Pigment Orange, C.I.
Pigment Red, C.I. Pigment yellow; diazo pigments, C.I. Pigment
Orange, anthanthrone pigments, anthraquinone pigments, C.I. Pigment
Violet, anthrapyrimidine pigments, quinophthalone pigments,
dioxazine pigments, flavanthrone pigments, C.I. Pigment Blue,
isoindoline pigments, isoviolanthrone pigments, metal-complex
pigments, C.I. Pigment Green; perinone pigments, perylene pigments,
C.I. Pigment Black, phthalocyanine pigments, pyranthrone pigments,
thioindigo pigments, triarylcarbonium pigments, Aniline Black,
Aldazine Yellow, C.I. Pigment Brown and liquid crystal polymer
pigments (LCP pigments).
[0015] The substrate can comprise metal, ceramic, glass, porcelain,
marble, natural stone, plastic, paper, rubber, wood, cardboard or a
combination thereof.
[0016] In another embodiment, the substrate is selected from the
group consisting of glass, lead-free glass, ceramic tiles, sanitary
ware, stoneware, porcelain, bricks, electronic quality ceramic
substrates, marble, granite, slate, limestone, metal, steel, brass,
copper, aluminum, tin, zinc, PVC, polyamides, polyolefins,
polyethylenes, polycarbonates and polytetrafluoroethylene.
[0017] In another aspect, described herein are methods of laser
marking a substrate in a desired pattern comprising: a) obtaining a
laser ink formulation comprising any laser marking composition
described herein; b) contacting the formulation with a substrate;
and c) irradiating the formulation with a laser having a wavelength
of between about 700 nm and 11000 nm, thereby causing the
composition to form a semi-permanent bond to the substrate and
forming the desired pattern.
[0018] Additionally, the method can comprise the step of
determining a desired pattern to be formed on the substrate.
[0019] The step of contacting the composition with a substrate can,
in one embodiment, comprise electrostatially applying a layer of
the composition onto the substrate or, in another embodiment,
spraying a layer of the composition onto the substrate.
[0020] The pattern can be any desired pattern such as a bar code,
an identifying code or a name.
DESCRIPTION OF INVENTION
[0021] Described herein are reaction-based laser or heat marking
(collectively referred to as "laser marking" or "ink formulation or
"ink laser formulation" or "laser ink composition", all synonymous)
which combines a reaction of one or more oxidizing/reducing agents
with a metal oxide (collectively, "marking component"). The marking
component is optionally dispersed, mixed or combined with a binder.
In some embodiments, the binder allows for better compatibility in
other formulations such as coatings, etc. In one embodiment, the
marking component can comprise one or more metal oxides, one or
more oxyanion or a combination one or more metal oxides with one or
more oxyanions. In another embodiment, marking component can
comprise one or more metal oxides in combination with one or more
oxidizing/reducing agents. The formulation described herein
provides a high-contrast color, black or white laser mark with
improved durability as compared with the current art. In some
embodiments, the black and/or white and/or color laser mark is a
high-contrast laser mark.
[0022] The marking component(s) (all or a portion of thereof) as
described herein are efficient absorbers of radiation at a
wavelength of from about 700 nm to about 12000 nm. In another
embodiment, the IR absorber pigments and dyes used in this
invention are an efficient absorber of radiation at a wavelength of
from about 780 nm to about 10600 nm. In yet another embodiment, the
IR absorber pigments and dyes used in this invention are an
efficient absorber of radiation at a wavelength of from about 780
nm to about 10000 nm. The present invention's marking components in
yet a further embodiment, absorbs radiation in the near infrared
region (NIR) of the electromagnetic spectrum (i.e. 780 to 3000
nm).
[0023] The formulation renders the marking to be permanent or
semi-permanent on a substrate or device to which it is applied to
provide a high-contrast marking. The present invention utilizes low
or high powered lasers to economically laser-mark substrates with
the formulation as described herein. Further, the methods for
providing an image on a substrate are discussed, which comprise
applying, to a relatively small area of the substrate, a
formulation comprising a binder and one or more metal oxides that
forms a high contrast image on irradiation with laser light.
[0024] This invention is based on the discovery that an image or
pattern using the formulation described herein can be formed by the
localized application or irradiation with a laser in the desired
pattern after uniform coating of a substrate. In some embodiments,
the present invention utilizes a low-energy laser, such as a diode
laser, typically emitting light at a wavelength in the range of 800
nm to 11000 nm.
[0025] It has been found that many oxyanions or metal oxides and/or
oxidizing/reducing agents (optionally in combination with a binder,
which in one typical embodiment is a polymer binder), absorb at the
wavelength of between 800 nm to 10,600 nm (for example, using
CO.sub.2 laser light) and undergo a color change. In one
embodiment, the color change is from a black or a dark color prior
to irradiation to yellow after irradiation at a certain light
wavelength. In another embodiment, the color change is-from black
prior to irradiation to a light or dark yellow after irradiation at
a certain light wavelength. In yet another embodiment, the color
change is from a first color (such as a dark color or black) prior
to irradiation to a second color (including but not limited to
yellow, red, green, blue, orange, purple, among others), which is
different than the first color, after irradiation at a certain
light wavelength. In another embodiment, the color change is from a
light color prior to irradiation to a dark color such as black
after irradiation at a certain light wavelength. The ink
formulations as described herein are effectively laser-selective,
and provide suitable material to be marked by the application of
laser light.
[0026] According to the present invention, the potential of
utilizing fibre, diode, diode array and CO.sub.2 lasers for imaging
applications on, for example, of plastic or cardboard packaging can
be realized. It has been shown that, by the application of liquid
film-forming formulations as described herein onto various
substrates to produce coatings capable of distinct colors, exposure
to near-IR sources produces good results.
[0027] The binder can be a solvent-based or aqueous-based,
depending on the desired application. It is understood that the
term "binder" includes a mixture of the resin and solvent, or
water-compatible resin (eg. Polyvinyl alcohol, Texicryl acrylic
emulsion, etc.) with water
[0028] In one embodiment, the resin is chosen from acrylics and
acrylates (including but not limited to copolymers of an alkyl
methacrylate or alkyl acrylate), alkyds, cellulose and cellulose
derivatives (including but not limited to nitrocellulose),
polysaccharides and polysaccharide derivatives, rubber resins
(including but not limited to chlorinated rubber and cyclised
rubber), keytones (including but not limited to methyl ethyl
ketone), maleics, formaldehydes, phenolics, epoxides, fumarics,
hydrocarbons, isocyanate free polyurethanes, polyvinyl butyral,
polyamides, shellac, polyvinyl alcohol, or any combination of the
foregoing.
[0029] The solvent can be chosen from methylated spirits, alkyl
acetate (including but not limited to methyl acetate, ethyl, propyl
or butyl acetate), propanol, polyvinyl alcohol, isopropanol,
n-propyl acetate, toluene, xylene, cyclohexanone, alkoxyethanol,
butoxyethanol, aromatic distillates having a boiling point of from
about 200.degree. C. to 310.degree. C., typically 240.degree. C. to
290.degree. C., or any combination of the foregoing.
[0030] The metal oxides are chosen from bismuth vanadate, vanadium
pentoxide, copper oxide, chromium oxide, iron oxide, zirconium
oxide, molybdenum oxide, tungsten oxide, silica, tin oxide, other
metal oxide compounds or any combination of the foregoing.
[0031] In one embodiment, the marking component comprises a metal
oxide mixture of bismuth vanadate, vanadium pentoxide, copper
oxide, chromium oxide and zirconium oxide. In another embodiment,
the marking component is a mixture of bismuth vanadate and vanadium
pentoxide.
[0032] In one embodiment, the oxidizing/reducing agent is selected
from potassium permanganate, sodium permanganate, calcium
permanganate, ammonium permanganate, or other permanganate salt,
perchlorate or a percholorate salt, chromate or a chromate salt, an
inorganic peroxide, hydrogen peroxide, ionic peroxide salts, acid
peroxides, sodium perborate, perborate salts, silver oxide,
tetroxide, osmium tetroxide, fluorine, chlorine, sulfuric acid,
acid peroxides, lithium hydroxide, chromium compounds, chromic
diacids, chromium trioxide, pyridinium chlorochromate, chromate
compounds, dichromate compounds, persulfuric acids, nitric acid,
nitrate compounds, Lithium aluminium hydride, hydride salts,
Nascent (atomic) hydrogen, Sodium amalgam, Sodium borohydride,
borohydride salts, tin(II) chloride, chloride salts, Sulfite
compounds, Hydrazine, zinc-mercury amalgam Diisobutylaluminum
hydride, Lindlar catalyst, molybdenum oxide, Oxalic acid, Formic
acid, Ascorbic acid, Phosphites, hypophosphites, phosphorous acid,
phosphate, phosphate salts, zinc phosphate, copper phosphate,
ammonium phosphate, tricalcium phosphate, Dithiothreitol,
hydroquinone, isoascorbic acid, thiols, glutathione, polyphenols,
Vitamin A, or iron(II) sulfate. In one embodiment, the
oxidizing/reducing agent is selected from potassium permanganate,
zinc phosphate, molybdenum oxide or sodium permanganate.
[0033] This method allows high contrast to be achieved between the
image and its immediate background with substantial savings in
cost, for packaging produced in high volume.
[0034] Other additives may optionally be added to the laser marking
formulation. Such additives can be chosen from reaction catalysts,
wax, drying additives (including but not limited to cobalt salts,
manganese salts, and zirconium salts), chelating agents,
antioxidants, surfactants (including but not limited to anionic
surfactants, zwitterionic surfactants, amphoteric surfactants,
nonionic surfactants), defoamers, alkali additives, reducing
agents, lubricating agents, pigments, sensitizers or any
combination thereof. Other additives include inert materials, such
as alumina, titanium oxide, zinc oxide, kaolin or mica.
[0035] In one embodiment, the marking component which comprises at
least one metal oxide and one oxidizing/reducing agent typically
comprises 10-70% w/w of the ink formulation, in another embodiment
10-50% w/w of the ink formulation, in another embodiment 1-35% w/w
of the ink formulation, in another embodiment 5-40% w/w of the ink
formulation.
[0036] In one embodiment, the metal oxide is a mixture comprising:
bismuth vanadate, of from about 40 to 80 wt % (weight percent) of
the mixture; vanadium pentoxide, of about 10 to 30 wt % of the
mixture; Copper (II) oxide, of about 5 to 15 wt % of the mixture;
Chromium oxide, of about 5 to 10 wt % of the mixture; and Zirconium
oxide of about 5 to 10 wt % of the mixture. In another embodiment,
the marking component comprises a mixture of metal oxides
comprising: bismuth vanadate, of about 40 to 80 wt % of the
mixture, vanadium pentoxide, of about 10 to 50 wt % of the mixture,
Copper (II) oxide (black) of about 5 to 15 wt % of the mixture. In
another embodiment, the marking component is a mixture of metal
oxides comprising: bismuth vanadate (about 40-80 wt % of mixture),
Vanadium Pentoxide (about 30-70 wt % of mixture) and Zirconium
oxide (about 5-10 wt % of the mixture).
[0037] In one embodiment, the metal oxides composition was prepared
using the quantities: bismuth vanadate (about 40-80 wt %), Vanadium
Pentoxide (about 10-30 wt %), Copper (II) oxide (black) (about 5-15
wt %), Chromium oxide (5-10 wt %) and Zirconium oxide (about 5-10
wt %). The components for the inventive sample were combined and
blended in a Waring blender. The mixture was then calcined in a gas
kiln to 1200-1325.degree. C. for several hours and cooled slowly.
The calcined mixture was pulverized to all particles less than 10
microns.
[0038] Formulations for use in the invention can be produced in
solvent and binder systems such as wood lacquers, nitrocellulose
lacquers, clear coats type printing inks, UV-curing inks etc.
[0039] Pigments, such as fumed silica or zinc stearate may also be
utilized. Typically, pigments are utilized in an amount of 1-85%
w/w of ink formulation. In other embodiment, pigments are utilized
in an amount of 1-60% w/w of ink formulation. In other embodiment,
pigments are utilized in an amount of 10-50% w/w of ink
formulation. In one embodiment, pigment can be any one or a
combination of monoazo pigments, C.I. Pigment Brown, C.I. Pigment
Orange, C.I. Pigment Red, C.I. Pigment yellow; diazo pigments, C.I.
Pigment Orange, anthanthrone pigments, anthraquinone pigments, C.I.
Pigment Violet, anthrapyrimidine pigments, quinophthalone pigments,
dioxazine pigments, flavanthrone pigments, C.I. Pigment Blue,
isoindoline pigments, isoviolanthrone pigments, metal-complex
pigments, C.I. Pigment Green; perinone pigments, perylene pigments,
C.I. Pigment Black, phthalocyanine pigments, pyranthrone pigments,
thioindigo pigments, triarylcarbonium pigments, Aniline Black,
Aldazine Yellow, C.I. Pigment Brown or liquid crystal polymer
pigments (LCP pigments). In another embodiment, pigments that can
be utilized include: monoazo pigments C.I. Pigment Brown 25, C.I.
Pigment Orange 5, 13, 36, 67, C.I. Pigment Red 1, 2, 3, 5, 8, 9,
12, 17, 22, 23, 31, 48:1, 48:2, 48:3, 48:4, 49, 49:1, 52:1, 52:2,
53, 53:1, 53:3, 57:1, 251, 112, 146, 170, 184, 210 and 245, C.I.
Pigment Yellow 1, 3, 73, 65, 97, 151 and 183; diazo pigments C.I.
Pigment Orange 16, 34 and 44, C.I. Pigment Red 144, 166, 214 and
242, C.I. Pigment Yellow 12, 13, 14, 16, 17, 81, 106, 113, 126,
127, 155, 174, 176 and 188; anthanthrone pigments C.I. Pigment Red
168, anthraquinone pigments C.I. Pigment Yellow 147 and 177, C.I.
Pigment Violet 31; anthrapyrimidine pigments C.I. Pigment Red 122,
202 and 206, C.I. Pigment Violet 19; quinophthalone pigments C.I.
Pigment Yellow 138; dioxazine pigments C.I. Pigment Yellow 138;
dioxazine pigments C.I. Pigment Violet 23 and 37; flavanthrone
pigments C.I. Pigment Blue 60 and 64; isoindoline pigments C.I.
Pigment Orange 69, C.I. Pigment Red 260, C.I. Pigment Yellow 139
and 185; isoindolinone pigments C.I. Pigment Orange 61, C.I.
Pigment Red 257 and 260, C.I. Pigment Yellow 109, 110, 173 and 185;
isoviolanthrone pigments C.I. Pigment Violet 31, metal-complex
pigments C.I. Pigment Yellow 117 and 153, C.I. Pigment Green 8;
perinone pigments C.I. Pigment Orange 43, C.I. Pigment Red 194;
perylene pigments C.I. Pigment Black 31 and 32, C.I. Pigment Red
123, 149, 178, 179, 190 and 224, C.I. Pigment Violet 29;
phthalocyanine pigments C.I. Pigment Blue 15, 15:1, 15:2, 15:3,
15:4, 15:6 and 16, C.I. Pigment Green 7 and 36; pyranthrone
pigments C.I. Pigment Orange 51, C.I. Pigment Red 216; thioindigo
pigments C.I. Pigment Red 88 and 181, C.I. Pigment Violet 38;
triarylcarbonium pigments C.I. Pigment Blue 1, 61 and 62, C.I.
Pigment Green 1, C.I. Pigment Red 81, 81:1 and 169, C.I. Pigment
Violet 1, 2, 3 and 27; Aniline Black (C.I. Pigment Black 1);
Aldazine Yellow (C.I. Pigment Yellow 101) and C.I. Pigment Brown
22, liquid crystal polymers (LCP pigments) or any combination
thereof.
[0040] When formulated as an ink for use as a solution, dispersion
or suspension, a suitable carrier liquid or solvent and other
components will be chosen accordingly. For example, inks and paints
can have the carrier liquid or an organic solvent such as
isopropanol, methyl ethyl ketone, ethanol or ethyl acetate,
optionally with amine and/or surfactant, e.g. in an amount of
20-80% w/w. The water based binders can also be used.
[0041] These compositions may be produced by using a) mechanical
mixing, b) ceramic ball grinding and milling c) silverson mixing d)
glass bead mechanical milling.
[0042] In some embodiments, the composition in part (for example
the pigment agglomerates) or in whole can be mixed in a "three roll
mill" or a "bead mill" or a "cavitation mixer". Generally, a three
roll mill is a series of cambered rollers rotating in opposite
directions. The pigment particles or agglomerated compound are fed
into a hopper above the two rear-most rollers and is dispersed by
the shear forces between the rollers. A doctor blade is fitted to
the front roller to remove the dispersed product. Roll pressure,
speed ratios and temperature must be carefully controlled to allow
reproducible dispersion. Each of the rolls is water cooled to
reduce the build up of frictional heat.
[0043] Bead Mills: A bead mill consists of a cylindrical chamber
filled with beads and surrounded by a water jacket for cooling. Ink
is pumped into the chamber and the beads (known as the `charge`)
set in motion by a series of spinning discs or pins. The charge
grinds the ink, breaking up the pigment clumps and evenly
dispersing the ink. The ink then flows out of the chamber through a
sieve and the charge remains behind to be re-used. The bead size
depends on the viscosity and rheology of the ink. Typical bead
sizes range from 1-2 mm for a high quality low viscosity product
such as a gravure ink up to 4 mm for a medium viscosity paste or
screen ink. The beads can be made of zirconium oxide, glass or
stainless steel. Certain beads discolour certain inks, so it is
important that each ink is tested with the different beads before
grinding to ensure that appropriate beads are used.
[0044] Cavitation Mixers: The use of cavitation mixers for the
production of resin solutions has already been discussed. However,
mixers of this type are also very efficient at dispersing certain
pigments, notably titanium dioxide, and allowing predispersion of a
number of others. In a highly viscous ink system a cavitation mixer
may be insufficient to ensure even dispersal and as a consequence
an additional sweeper blade may be added.
[0045] By application of liquid film-forming inks onto various
substrates, coatings capable of distinct color change can be
produced. Exposure to near-IR sources can produce dramatically
different results, dependent primarily on the formulation of the
ink. A composition of or for use in the invention can be used to
produce an IR-sensitive coating that can be applied by a range of
methods such as flood-coating, flexo/gravure etc. The coating can
be applied to a range of substrates such as paper, paperboard,
flexible plastic film, corrugate board etc.
[0046] The marking component as described herein can be inorganic
or organic in nature, depending on the specific application
desired. It should have thermally stability at above 150.degree.
C., more typically above 200.degree. C., and possess good light
stability and weatherability profiles. In one embodiment, the
marking component is colorless or imparts minimal color in the
finished coating formulation
[0047] The ink laser formulation as described herein binds, upon
irradiation with a laser of certain wavelength, to a workpiece,
machine, material, device or substrate (It is understood that the
term "substrate" also includes a workpiece, machine, material or
device.) The substrate can be made from a conductive or dielectric
material, or a combination of both. Examples of suitable substrates
for use with the present invention include but are not limited to
metal, glass, brick, ceramic, porcelain, plastics, marble, granite,
natural stone, paper, cardboard and corrugated cardboard, and the
like.
[0048] Glass substrate compositions capable of being laser-marked
by the present invention include lead as well as lead-free glasses
such as soda lime silicates, borosilicates, aluminum silicates,
fused silica and the like.
[0049] Ceramic substrates capable of being laser marked by the
present invention include tiles, sanitary ware, stoneware bodies,
porcelain bodies and bricks, as well as electronic quality ceramic
substrates such as silica, alumina, aluminum nitride, etc.
[0050] Natural stone substrates can include marble, granite, slate,
limestone and the like. Suitable metal substrates include but are
not limited to steel, brass, gold, silver, platinum, copper,
aluminum, tin, zinc and the like.
[0051] Typical plastic substrates include PVC, polyamides,
polyolefins, polyethylenes, polycarbonates and
polytetrafluoroethylene.
[0052] Combinations of the above substrate materials may also be
used, such as glass coated steel workpieces, glass coated ceramic
substrates or workpieces as sell as any substrate coated with an
epoxy or enamel.
[0053] Exemplary substrates that can be laser-marked in accordance
with the present invention include electronic devices, printed
circuit boards, automotive parts, automotive glass, aerospace
parts, medical devices, tooling, consumer products, packaging,
glass bottles, metal cans, metal tags, bricks, tiles, coated tiles
and ceramics, totes, plastic containers, plumbing, electrical and
construction supplies, lighting and the like.
[0054] The composition or ink laser formulation can be applied to
the substrate in any variety of applications. In one embodiment,
the composition is sprayed onto the substrate. Typically, the
composition is applied through use of aerosol-type spraying or
airbrushing-type spraying. In this way, the application can be
generally uniform in coating. In another embodiment, the
composition is applied through use of a brush, including but not
limited to foam brush application and bristle brush application. In
another embodiment, the composition is applied as an aqueous
application, including but not limited to screen printing ink
application pad printing ink application and the like.
[0055] The laser mark is permanent, which means in one embodiment
that such mark is resistant to both scrubbing and re-oxidation. The
compounds used in the present invention can be in the form of
particles having a D3,2 average particle size in the range from 10
nm to 10 .mu.m, typically less than 1 .mu.m, and more typically
less than 100 nm. In one embodiment, the inorganic compounds used
in the present invention can be in the form of particles having an
average particle size in the range from 10 nm to 10 .mu.m.
[0056] Any suitable laser or similar irradiating device can be used
in conjunction with the present invention. In one embodiment,
imaging or patterning of a substrate is accomplished through the
use of a diode array and CO.sub.2 lasers, namely, ND:YAG (1064 nm
wavelength) and industrial CO.sub.2 (10,600 nm wavelength).
[0057] In another embodiment, additional color-forming components
can be added to the formulation. Examples of suitable color-formers
include one or more of a range of conventional materials such as
electron-donating materials, e.g. phthalides, fluorans and leuco
dyes, for example crystal violet lactone. Lewis acids, whether
electron-accepting or acid-generating, may also be used; examples
are hydroxybenzoate, bisphenol A, zinc stearate and others. In
another embodiment, metallo-porphyrins, metallo-thiolenes,
metallo-polythiolenes, metallo-phthalocyanines, aza-variants or
annellated variants of any of these, pyrylium salts, squaryliums,
croconiums, amminiums, diimoniums, cyanines and/or indolenine
cyanines can be utilized.
[0058] In one embodiment, the present invention is a method of
laser-marking a substrate comprising a) obtaining a laser ink
formulation comprising a marking component of: a metal oxide and an
oxidizing/reducing agent; b) contacting the formulation with a
substrate; and c) irradiating the composition with a laser having a
wavelength of between about 700 nm and 11000 nm, thereby causing
the formulation to form a semi-permanent bond with the
substrate.
[0059] In yet another embodiment, the present invention is a method
of marking a substrate comprising: a) obtaining a laser ink
formulation comprising a marking component and a binder; c)
determining a desired pattern to be formed on the substrate; b)
contacting the laser ink formulation with a substrate; and c)
irradiating the composition in the desired pattern with a laser.
Typically, the laser is in the IR or Near-IR range, having a
wavelength of between about 700 nm and 11000 nm. This causes the
composition to form a semi-permanent bond with the substrate in the
form of the pattern.
EXAMPLE 1
[0060] Laser marking paint/ink: Nitrocellulose lacquer (20-40%
solids) (one liter) in the solvents Butyl Acetate and Toluene was
added to a mixture of very fine mix of calcined mixture (less than
10 microns all particles) of zinc phosphate (as oxidizing/reducing
agent), Copper (II) oxide, Vanadium Pentoxide. The paste was mixed
in a three roll rubber mill to disperse the oxides and binder. The
resultant paste was applied on glass, metals, ceramics and plastics
and were tested using 25 Watt CO.sub.2 laser (10,600 nm wavelength)
at 90% power, 30% speed and 1000 PPI. Upon observation, the laser
mark was black in color against yellow background.
EXAMPLE 2
[0061] Nitrocellulose lacquer (one liter) in solvents Butyl Acetate
and Toluene was added to a mixture of very fine mix of calcined
mixture (less than 10 microns all particles) of zinc phosphate,
vanadium pentoxide with tungsten oxide and cobalt oxide. The ink
was mixed in a three roll rubber mill to disperse the oxides and
binder. The resultant paste was applied on glass, metals, ceramics
and plastics and were tested using 25 Watt CO.sub.2 laser (10,600
nm wavelength) at 90% power, 30% speed and 1000 PPI. Upon
observation, the laser markings were light blue in color.
EXAMPLE 3
[0062] The solids in example one were replaced with red iron oxide,
Molybdenum Oxide and Vanadium Pentoxide. The ink was mixed in a
three roll rubber mill to disperse the oxides and binder. The
resultant paste was applied on glass, metals, ceramics and plastics
and were tested using 25 Watt CO.sub.2 laser (10,600 nm wavelength)
at 90% power, 30% speed and 1000 PPI. Upon observation, the laser
markings were grey in color.
[0063] It is apparent that embodiments other than those expressly
described herein come within the spirit and scope of the present
claims. Accordingly, the invention as described is not defined by
the above description, but is to be accorded the full scope of the
claims so as to embrace any and all equivalent compositions and
methods.
* * * * *