Note: Descriptions are shown in the official language in which they were submitted.
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3-1525311~2/+/CGM 296
Laser Marking of Pigmented High Molecular Weight Polymsr Surfaces
The present invention relates to a process for laser marking of
pigmented high molecular weight organic polymer surfaces and to the
marked material.
It is known e.g. from a reprint of Pack Report No. 1, January 1981,
page 4, to mark plastics materials such as PVC by irradiation with a
laser beam such that the energy applied thereto effects a mechanical
change or discolouration of the plastics material at the area which
is so marked. The lasers used for this purpose are CO2 lasers which
operate in the infra-red range at a wavelength of 10.6 ~m.
It is also known to mark plastics parts containing a filler that is
capable of being changed in colour by means of an applied energy
radiation. Thus, according to US patent specification 4 307 047,
plastic keys made of a base plastic material of ABS and containing
as colour changeable filler a colouring powder that responds to heat
irradiation ~heat radiation indicator) are marked by irradiation
with a laser beam, said filler producing a permanent change in
colour when subjected to irradiation with heat in the form of the
mark which it is desired to apply. The laser employed is an Nd:YAG
laser having a wavelength of 1.06 ~m (= 1064 nm) in the infra-red
range.
Finally, German Auslegeschrift 2 542 680 discloses a process for
recording information, in which an acetyl acetonate, dissolved in a
polymer, is used as light-absorbing substance and a laser beam
having a wavelength in the visible range is used as light source.
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The present invention relates to a process for marking a coating,
film or molded article of a high molecular weight organic polymer
composition wherein the high molecular weight organic polymer is
selected from the group consisting of polyethylene, polypropylene,
polyisobutylene, polystyrene, polyvinyl chloride, polyvinylidene
chloride, polyvinyl acetals, polyacrylonitrile, polyacrylates, poly-
methacrylates, polybutadiene, acrylbutadiene styrol copolymers,
ethylene vinyl acetate copolymers, polyesters, polyamides, poly-
imides, polycarbonates, polyurethanes, polyethers, polyacetals, the
condensates of formaldehyde and phenols (phenolic plastics), the
condensates of formaldehyde and urea, thiourea and melamine ~amino-
plasts), the epoxy resins, the polyesters used as surface-coating
resins, and as film formers or binders for varnishes or printing
inks, linseed oil varnish, nitrocellulose, alkyd resins, phenolic
resins, melamine resins, acrylic resins and urea/formaldehyde
resins, or mixtures of above polyplastics, as well as co-condensates
and copolymers thereof, which polymer composition contains at least
one radiation-sensitive additive effecting a change in colour upon
radiation in amounts from 0.001 to 10 % by weight, based on said
high molecular weight organic polymer, which radiation-sensitive
additive is an inorganic pigment, an organic pigment, a polymer-
soluble dye or a mixture thereof, which process comprises irradiat-
ing said polymer composition containing the additive with a pulsed
laser beam having a wavelength in the close ultra-violet range,
visible range, close infrared range or a combination of two or more
of these ranges, wherein the laser beam with pulse contents of
micro-Joule to Joule, intensities of kilowatt/cm2 to 100 mega-
watt/cm2, pulse durations of microseconds to picoseconds and
frequencies of hertz to 250 megahertz is applied to the surPace of
the composition to be marked according to the form of the graphic
symbol to be applied, such that a change in colour of marked
contrast and discernable to the eye is induced at the time of
exposure at the irradiated areas and corresponding to the form of
said graphic symbol, without perceptible damage to the surface of
the marked polymer composition.
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The high molecular organic material can be of natural or synthetic
origin. Such material may comprise for example natural resins 7
drying oils or rubber. However, it may also comprise modified
natural materials, for example chlorinated rubber, oil-modified
alkyd resins or viscose or cellulose derivatives such as acetyl
cellulose and nitrocellulose and, in particular, man-made organic
polyplastics, that is to say, plastics which are obtained by
polymerisation, polycondensation and polyaddition. The ollowing
products may be mentioned in particular as belonging to this class
of plastics: polyethylene, polypropylene, polyisobutylene, poly-
styrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl
acetals, polyacrylonitrile, polyacrylates, polymethacrylates or
polybutadiene, and copolymers thereof, in particular ABS or EVA;
polyesters, in particular high molecular esters of aromatic poly-
carboxylic acids and polyfunctional alcohols: polyamides, poly-
imides, polycarbonates, polyurethanes, polyethers such as poly-
phenylene oxide, polyacetals; the condensates of formaldehyde and
phenols (phenolic plastics), and the condensates of formaldehyde and
urea, thiourea and melamine (aminoplasts); the polyadducts and
polycondensates of epichlorohydrin and diols or polyphenols known as
epoxy resins; and also the polyesters used as surface-coa~ing
resins, namely saturated polyesters, for example alkyd resins, as
well as unsaturated polyesters, for example maleic resins. It must
be emphasised that not only the homogeneous compounds can be used in
the practice of this invention, but also mixtures of polyplastics,
as well as co-condensates and copolymers, for example those based on
butadiene.
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Also suitable are high molecular organic materials in dissolved form
as film formers or binders for varnishes or printing inks, e.g.
linseed oil varnish, nitrocellulose, alkyd resins, phenolic resins,
melamine resins, acrylic resins and urea/formaldehyde resins, the
films obtained from which may be marked by the method of this
invention. Particularly preferred plastics for use in the method o
this invention are linear polyesters, polystyrene, polyethylene,
polypropylene, ABS, polyacetals, polyphenylene oxide, polyamide,
polycarbonate, polymethylmethacrylate and epoxy resins.
Eligible additives which effect a change in colour are inorganic and
organic pigments and polymer-soluble dyes which absorb light
preferably in the close ultraviolet range and/or visible or close
infra-red range.
By "visible range" is meant the range between 0.38 ~m and 0.78 ,um,
by "close infra-red range" the range be~ween 0.78 ~m and 2 ~m, and
by "close ultraviolet range" the range between 0.25 ~m and 0.38 ~m.
Particularly suitable additives are those that absorb light in the
visible range.
Examples of inorganic pigments suitable for use as additives that
are able to effect a change in colour are white pigments such as
titanium dioxides (anatase, rutile), zinc oxide, antimony trioxide,
zinc sulfide, lithopones, basic lead carbonate, basic lead sulfate
or basic lead silicate, and also metal oxides such as iron oxides
[e.g. C.I. Pigment Yellow 42, 43 or Red 101 or 102], chromium
oxides, nickel antimony titanate ~C.I. Pigment Yellow 53], chromium
antimony titanate [e.g. C.I. Pigment Yellow ll8], manganese blue
~C.I. Pigment Blue 33], manganese violet ¦C.I. Pigment Blue 161,
cobalt blue and cobalt chromium blue ~e.g. C.I. Pigment Blue 28
or 36], cobalt nickel grey [C.I. Pigment Black 2S] or ultramarine
blue [C.I. Pigment Blue 29], Berlin blue [C.I. Pigment Blue 27j,
lead chromates and lead sulfochromates [C.I. Pigment Yellow 34],
molybdate orange and molybdate red [C.I. Pigment Orange or Red 103,
104], as well as metal sulfides such as cadmium sulfide [C.I.
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Pigment Yellow 37, or Orange 20], arsenic disulfide and antimony
trisulfide [C.I. Pigment Yellow 39] or cadmium sulfoselenides [C.I.
Pigment Orange 20], zirconium silicates such as zirconium vanadium
blue [C.I. Pigment Blue 71] and zirconium preseodyme yellow [C.I.
Pigmente Yellow 159], and also carbon black or graphite in low
concentration.
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Examples of organi~ pigment~ as additives are azo, azomethine,
methine, anthraquinone, lndanthrone, pyranthrone, flavanthrone,
benzanthrone, phthalocyanine, perinone~ perylene, dioxazlne,
thloindigo, isoindoline, isoindolinone, quinacridone, pyrrolopyrrole
or quinophthalone plgments, and also metal complexes of e.g. azo,
azomethine or methine dyes or metal salts oE azo compounds.
Suitable polymer-soluble dyes are e.g. disperse dyes such as tho3e
of the anthraquinone series, for example hydroxyanthraquinone6,
aminoanthraquinone6, alkylaminoanthraqulnone6, cyclohexylaminoanthra-
~uinones, a~yl~minoanthraquinones, hydroxyaminoanthraquinones or
phenylmercaptoanthraquinones, as well a6 metal complexes o~ aæo
dyes, in particular 1:2 chromium or cobalt complexes of monoazo
dyes, and fluo~escent dyes such as those of the coumarln, naphthal-
imide, pyrazoline, acridine, xanthene, thioxanthene, oxazine,
thiazlne or benzthiazole series.
The polymer-soluble dye6 are preferably used in combination ~ith
filler6 andlor pigments, in particular with inorganic pigment~ such
as titanium dioxide.
In the practice of this invention, pigments or polymer-soluble dyes
can be u~ed with or without pigment additives. Care must only be
taken that they are compatible with the high molecular material
employed and that they do not impair its mechanical or other
properties.
Suitable pigment addltives are e.g. fatty acid3 of at least 12 car-
bon atoms, for example ~tearic acid or behenlc acid and the amides,
salts or esters thereof such as magnesium stearate, zinc stearate~
aluminium stearate or magnesium behenate, and also quaternary
ammonium compounds such as tri(C1-C4)alkylben2;ylammonlum salts,
waxes such as polyethylene wax, resin acid3 such as abietlc acid,
colophonium soap, hydrogenated or dimeri~ed colophonium, Clz-cla
paraffin disulfonic acid6 or alkylphenols.
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In the practice of this invention it i~ prefer~ed to use the
metal-coDtaining pigments such 89 inorganic plgments and the metal
complexes of azo, azomethine or methine dyes.
Also preferred are azo, azomethine, methine, anthraqulnone, phthalo-
cyanine, perylene, dioxa~ine, thioindigo, i~oindoline, l~oindolin-
one, quinacridone or py~rolopyrrole plgments.
The high molecular organic material contains the additive e~ecting
a change in colour in amounts from 0.001 to 10 % by wei~ht, pre-
ferably from 0.01 to 3 % by weight, based on said high molecular
organic material.
The addition of the additive that effects a change in colour of the
high molecular organic material for proces~ing to moulded articles
is made in a manner known per se5 for example by incorporating such
sn additive, which may be in the form of a masterbatch, in~o the
substrates using extruders, roll mills, mixing or grinding machines.
The resultant material i9 then brought into the desired final form
by methods which are known per se, for example calendering9 moul-
ding, extruding, coating, cas~ing or by in~ection moulding. It is
often desirable to incorporate plastlcisers into the high molecular
organic compounds before processing in order to produce non-brittle
mouldings or to diminish their brittlsness. Suitable plasticisers
are for example esters of phosphoric acid, phthalic acid or sebacic
acid. In the method of this invention, the plasticisers may be
incorporated before or after working the additive into the polymer.
Depending on the end use, further substance~ may be added to the
high molecular organic material, for example fillers such as kaolin,
mica, feldspar, wollastonite, aluminium silicate, barium sulfate,
calcium sul~ate, chalk, calcite and dolomite, as well as light
stabilisers, antioxidants, flame retardants, heat stabilisers, gla~s
fibres or processing auxiliaries convent~onally employed in the
processing of plastic~ aDd which are kno~n to the skilled person.
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To prepare the varnishes and printing lnks suitsble for u3e in -thls
invention, the hlgh molecular organlc ~aterials and the additive
that effects a change in colour, with or wlthout the addition of
further auxilisrie6 of varnishQs and printing inks, are finely
dispersed or di~solved in a join~ organic solvent or mixture of
solvents. The procedure may be such that the indlvldual components,
or also ~everal components jointly, are dispersed or di~olved and
then all the components are combined. The homogeniset varnlsh or
printing ink is then applied to a substrate by a method which is
known per se and baked and dried~ and the film 90 obtained is
subsequently marked by the process of this invention.
Energy-rich sources such as lasers are used to mark the high
molecular organic materials suitable for use in the practice of this
invention. The procedure comprises applying the energy source to the
surface of the material to be marked, according to the form of the
graphic symbols to be applied, and optionally focussing said energy
source such that a change in colour is induced at the lrradiated
area~ without perceptible damage to the ~urface of the marked
material.
Exemplary of such energy sources are solid state pulsed lasers such
as ruby lasers or frequency multipli~d Nd:YAG lasers, pulsed lasers
with boo~ter such as pulsed dye lasers or Ra~an shifter, and also
continuous wave lasers with pulse modification~ (Q-switch, mode
locker), for example on the basis of CW Nd:YAG lasers with frequency
multiplier or CW ion lasers (Ar, Kr~, as well as pulsed metal vapour
lasers, for example copper vapour laser~ or gold vspour laser6, or
high capacity pulsad ~emi-conductor lasers~
Depend~ng on the laser ~ystem employed, pulse contents of up to
several Joule~, intensit~es of up to 10l2 W/cm25 pulse duration3 of
up to 10 15 seconds and frequencie~ of up to 109 ~z are pos3ible.
Pulse contents of micro-Joule to Joule7 intensitie~ of kilowatt/cm2
to 100 megawatt/cm2, pulse durat~ons of ~icrosecond~ to pic~3econds5
and ~requencie~ of hertz to 250 megahertz are advantageously used.
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lt i9 preferred to uge la~erg with pulsed light, for example those
listed in the following table. Especially preferred lasers are
pul~ed or pul~e-modified, frequency doubled ~d;YAG la~er~ or metal
vapour lasers ~uch as Au- or, in particular, Cu-vapour la~er~.
The following table li~ts a number of commercially available la~er~
which may be ~ultable in the practice of thia invention.
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_y~/Representative ¦ commercially j Principal wave1ength i
ava$1able lengths)
. types
Solid state pulsed
ruby laser (938R6R4L-4)694 (347)
~Nd:YAG laser Quanta Ray1064, (532
~Alexandrite laser Apollo (7562) 730-780
Pulsed lasers with
booster such as Quanta Ray UV-IR
Raman shifter (RS-1)
dye laser Lambda Physikca.300-1000
FL 2002
CW laser with pulse
modification 532
~Nd:YAG (Q-Switch,2~) asermetrics
~argon (mode-locked) Spectra- 514,5
~hysics _
pulsed metal vapour
Cu vapour laser Plasma- 510,578
Kinetics 751 628
~Au vapour laser Kinetics
~Mn vapour laser l Oxford 723
j Pb vapour laser j J Laser CU I _ .
Se~i-conductor diode Type LD 65 905
" Array STANTEL 905
¦ . I Type LF 100 i . . _
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In the practice of this invention, the laser employed will be for
example a pulsed, frequency doubled Nd:YAG laser with a pulse
content of about 250 milli-Joules/cm2, a maximum capacity of about
40 megawatts, pulse durations of 6-8 nanoseconds and a frequency of
20 Hz (Quanta Ray DCR-2A, available from Spectra Physics, ~ountain
View, California).
If a copper vapour laser (Plasma Rinetics 151) is used, exposure
will be carried out with a pulse content of e.g. 250 milli-
Joules/cm2, a maximum capacity of about 10 kW, a pulse duration of
30 nanoseconds and a frequency of 66 kHz.
Lasers whose parameters can be readily adj~sted, for example pulse
content and pulse duration, permit the best possible adaption to the
requirements of the materials to be marked.
The best wavelength to be selected for radiation is that at which
the additive effecting a change in colour absorbs light most
strongly and the high molecular organic material least strongly.
Three different methods are suitable for laser marking in the
practice of this invention: the mask method, the linear marking
method and the point matrix method. In these last two mentioned
methods (dynamic focuqsing), the laser is preferably combined with a
laser marking system so that high molecular organic material can be
marked with any, e.g. computer-programmed, dlgits, letters and
special symbols at the point where the laser beam strikes.
The choice of laser system in respect of capacity and frequency
depends basically on the marking method employed. The high capacity
and low frequer.cy of the solid state pulsed lasers are preferr~d for
mask exposure. Ths average to low capacities and rapid frequsncies
of pulsed metal vapour lasers or of continuous wave lasers with
pulse modifications are preferred for producing markings that
require dynamic focussing. Beam deflection can be effected e.g.
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acou~to-optically, holographically, with galvo-mirrors or polygon
scanners. Dynamic focussing mske~ possible an extremely flexible
marking, as the mark~ can be produced electronicslly.
A very wide range of markings can be produced by the present
lnvention. Examples are: variable text programming of nu~nerical
symbols by inp~tting text with a video display unit, test prograMs
of standard symbols or special symbols such as monograms, logos~ or
frequently recurring data, continuou6 piece numberlng, input of
measurable vari~bles, input of a stored program, linesr marking or
also decorations.
It is also possible in the practice of this invention to mark a very
wide range of plastics parts or mouldings ag well as varnish or
printing ink films. Ribbons, plates, tubes and profiles, keys and
plastics-coated electronio components may be cited by way of
example.
Typical utilities are the marking of circuit~, printed circuit
boards, printed circuitR, act~ve and passive electronic components,
encapsulated high voltage transformers, plug sockets~ casings,
mechanical components of preci~ion technology and of the watch-
making industry, automotive components, keyboards, electronic
components, cables, tube~, varnishes, ~heets and packaging ~heets,
as well as currency notes and security documents.
The present invention makes it possible to produce a marking that i~
indelible and which is therefore abrasion- and ~cratch proof. The
markings obtained in this invention are also corrosion-proof,
di~ensionally stable, free from deformation, fast to light, heat and
weathering, easily legible, snd have good edge definition. In
addition~ there is virtually no impairment of the mechanical and
physical properties of the marked material. The impression dspth of
the marking depends on the marked material and i~ about l mm, with
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minimum damage to the high molecular organic material. Hence lt i~3
possible to obtained markings thst give rise to no perceptible 10~8
of 3ur$ace gloss.
In the process of this invention, a change in colour of ~arked
contrast occur~ at the irradiated area of the materlal upon exposure
to a lase~ bea~. Usually the change in colour will be towards black;
but 19 i3 poA9ible to effect other colour changss, e.~. red or
yellow to brown, red or yellow to white or black to white, depending
on the additive employed that effects the change in colour.
In tha practice of this invention, semi-trsn~parent boards and
~heets can be marked in a particularly attractive manner, charac-
terlsed in that the marking appears opaque when viewed in reflected
light, but becomes almost transparent in a shsde of the ~tarting
colour before marking when vlewed by transmitted llght~ The contrast
when viewed in reflected light as well a~ the shade of the transpar-
ent colour can be controlled in si~ple manner by ad~usting the las~r
pulse parameters.
ln the following Examples parts are by weight, unles~ otherwise
indicated.
Example l
a) Coating of metal plates with sintering powders
Small ~teel plates messurlng 40 x 40 x 2 mm, which have been
degreased but not deflashed, are hea~ed in an oven to 120~C. Then
the plates are immersed rapidly for 3 seconds in a fluidised bed
with per se known epoxy resin sinterlng powders ~e.g, a mixture
comprising 38 parts of an advanced epoxy resin based on bisphenol A
and haviDg an epoxide content of 1.3 equivalents per kg, }4 parts o
a bromine-oontalning epoxy resin based on tetrabrominated big-
phenol A having an epox~de content of 2.0 to 2.2 equivalents per kg,
4.5 parts of an acrylate-based levelling agent, 5.8 pArts of
benzophenonetetracarboxyllc dianhydride as hardener, 29.S parts of
Al203-3H20 and 18.5 parts of quartz flour as fillers, 0.3 part of
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silicic acid (Aerosil~ 380, ex Degussa, West Germany) and 1.3 parts
of lmidazole as accelerator] and 2 parts of an addltive that effects
a change in colour. This procedure of heating and immer~ing i9
repeated once, affordlng a glossy flame-retardant coatlng with a
layer thickne~s of 250-400 ~Im. For complete curing, the coated
plates are stored for 15 minutes at 180C.
b) Marking
The steel plates coated by the general procedure descrlbed in a),
snd containing as additive that effect~ a change in colour 1.8% by
we~ght of C.I. Pigment Violet 19 (quinacridone), a~e then irradiated
by the beam of an ~d:YAG pulsed laser (Quanta Ray DCR-2A, svailable
from Spectra Physics, Mountain View, USA) wlth light pulses of
6-8 ns (nanoseconds~ at a wavelength of 0.532 ~m (frequency doubled
beam) and a pulse content of 120 mJ ~milli-~oules), to give a strong
black markng on the epoxy plates without any perceptible surface
damage.
Example 2: 99.7 g of polybutylene terephthalate [Crastin~ S 600, ex
Ciba-Geigy AG, Switzerland, hereinafter abbreviated to PBTP] are
mixed with 0.3 g of a red iron oxide pigment (Bay~errox~ 140,
ex Bayer, West Germany, C.I. Pigment Red 101) and thl~ mixture i8
processed to small plates measuring 4 x 5 cm (3 mm thick) in an
in~ection moulding machine at a cyllnder temperature of 250~C, a
~ould temperature of 80C and a cycle time of 40 second~. These
plates are irradiated with sn Nd:YAG pulsed laser as described in
Example l b). The black mark~ng ao obtained show~ no change in
colour after 250 hours exposure in a Weather-Ometer (cycle 45~.
Example 3: Ep~xy plates prepared in accordance with Example 1, but
using 2 g of C.I. Pigment Yellow 139 (isoindoline) as addltive that
effects a change of colour9 are marked in dar~ brown with good
contrast in accordance wi~h the procedure described in Example lb)o
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Example 4: Epoxy plates prepared in accordance with Example l, but
using 2 g of Irgazin Red ~PT lPerylene Red, ex Ciba-Geigy, Swltzer-
land, C.I. Pigment Red 224] as additive that effects a change of
colour, are marked ln black with good contrast in accordance with
the procedure described in Example 1 b).
Example 5: PBTP plates prepared in accordance with Example 2, but
using 0.3 g of a chromium yellow pigment (Chromium Yellow~ GMN 35,
ex Ciba-Geigy, Switzerland, C.I. Pigment Yellow 34) as addit~ve that
effects a change of colour, are marked in black with good contrast
in accordance with the procedure described in Example lb).
Example 6: Following the procedure of Example 2, but using 0.2 g of
a cadmium red pigment (Cadmium Red~ conc. X-2948, ex Ciba-Geigy,
Switzerland, C.I. Pigment Red 108) instead of 0.3 g of an iron oxide
pigment, the PBTP plates so obtained can be marked black with good
contrast by laser lrradiation in accordance with Example lb).
Example 7: PBTP plates prepared in accordance with Example 2, but
using 0.15 g of a molybdate red pigment (Molybdate Red~ AA-3, ex
Ciba-Gelgy, ~witzerland, C.I. Pigment Red 104) as additive that
effects a change in colour, are exposed to irradiation by a laser
beam in accordance with Example l b) at lower intensity (< 50mJJcm2)
to produce a yellow marking and at greater intensity (> 50 mJ/cm2)
to produce a black marklng.
Example 8: PBTP plates prepared in accordance with Example 2, but
uslng 8 g of anti~ony trioxide as additive that effects a change of
colour, are marked in black when exposed to laser irradiation in
accordance with Example lb).
Example 9:30 g of a 5S % by weight solution of an alkyd resin and a
melamine/formaldehyde resin [mixture of 67.5 g of a 60 % by weight
solution of an alkyd resin iD xylene (available from Bayer under the
registered trademark Alkydal~ F27), 26.4 g of a 55 % by weight
solution of a melamine/formaldehyde resin ln a 1:1 mixture of
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butanol/xylene (avallable from Casella under the registered trade-
mark Maprenal~ MF 590), l.1 g of xylene, 4.0 g of sthylene glycol,
1.0 g of silicone oil A~ (1 % in xylene) [available from Bayerl and
2 g of methylcellosolve], 8 g of methyl isobutyl ketone and 2 g of
Molybdate Red~ AA-3 (ex Ciba-Geigy, Switzerlsnd, C.I. Pigment
Orange 104) as additive that effects a change of olour, are mixed
in a 100 ml glass flask wlth screw top containing 135 g of glass
beads of 3.5 mm diameter. This mixture is dispersed Eor 16 hours in
a laboratory vibratory mill. The varnish so obtained is then applied
by conventional methods wit~ an applicator to give wet films with a
thickness of 150 ~m on metal and on a black-white contrast panel
conventionally employed ln the paint industry. The films are then
baked for 30 minutes at 130C. The finishes so obtained are then
irradiated in accordance with Example lb). In both cases a grey
marking is obtained without any perceptible damage to the surfaces
o~ the varnish films.
Example lO: Varnish films produced on metal and on a black-white
contrast panel as described in Example 9, except that 2 g of Cadmium
Yellow~ X-2822 (cadmium pigment of Ciba-Geigy, Switzerland,
C.I. Pigment Yellow 35) are used instead of 2 g of Molybdate Orange,
are marked in black with good contrast in accordance with
Example lb).
Example 11: Varnish fllms produced on metal and on a black-white
contrast panel as described in Example 9, except that 2 g of
Bayferrox~ 140 M (iron axide red pigment of Bayer, C.I. Pigment
Red 101) are used instead of 2 g of Molybdate Red, are marked in
grey with good contrast in accordance with Example lb~.
Example 12: 30 g of the 55 % by weight solution of an al~yd resin
and a melamine resin described in Example 9, 8 g of methyl isobutyl
ketone, 7.6 g of titanium dioxide (Bayer Titan~ RKB 3, ex Bayer) and
0.4 g of Molybdate Red~ M-3 (ex Ciba-Geigy, Switzerland) as
additive that effects a change in colour, are mixed in a lOO ml
glas~ flask with screw top containing 135 g of glass beads of
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3.5 diameter. Thi~ mixture is then dispersed for 16 hours in a
laboratory vibratory mill. The varnish so obtained is applied with
an applicator to give 150 ~m wet films on metal and on a black-whlte
contrast panel conventionally employed in the paint industry and the
films are baked for 30 minut~s at 130C. The finishes are then
irradiated in accordance with Example lb). A grey ~arking i8
obtained.
Example 13: Varnish films produced on metal and on a black-whlte
contrast panel as described in Example 12, except that 2 g of
Cadmium Yellow~ X-2822 (cadmium pigment of Ciba-Geigy, Switzerland,
C.I. Pigment Ysllow 35~ are used instead of 0.4 g of Molybdate Red,
are marked in grey with good contrsst in both case~ in accordance
with Example lb).
Example 14: Yarnish film~ produced on metal and on a black-white
contrast panel as dascribed in Example 12, except that 2 g of
Bayferrox~ 140 M (iron oxide red pigment of Bayer~ are used in~tead
of 0.4 g of Molybdate Red, are marked in light-blue with good
contrast in both cases in accordance with Example lb).
Exa~ple l5: Vsrnish films produced on metal and on a black-white
contra~t panel as described in Example 12, except that 2 g of
Filester~ Yellow 2648 A (anthraqulnone derivat~ve of Ciba-Geigy,
Switzerland, C.I. Pigment Yellow 147) are u~ed instead o~ 0.4 g of
Molybdate Red, are marked in grey with good contrast in accord-
ance wlth Example lb~.
Example 16: Following the procedure of Example 2, marking i9
effected with a laser beam having a wavelength of 355 nm (triple
frequency of an Nd:YAG la~er, Quanta Ray DCR-2A9 available from
Spectra Physics, USA) instead of a laser beam having a wavelengtb of
0.532 ~m. The pulse duration i8 6-8 n~ and the pulse content 50 mJ
and the beam is focussed through a glass lan~ with a focal length of
250 mm to give a beam diameter of 1-2 ~m. A black marking is
obtained.
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- 16 -
Example 17: Following the procedure of Example 5, marklng i9
effected out wlth a laser beam having a wavelength of 355 nm (triple
frequency of an Nd:YAG laser, Quanta Ray DCR-2A, avallable from
Spectra Physics, USA). The pulse duration is 6-8 ns and the pulse
content 50 mJ and the beam i5 focussed through a glass lens with a
focal length of 250 mm to glve a beam diameter of 1-2 mm. Black
markings with good contrast are obtalned.
Example 18: Marking is effected out in accordance with Example 7,
but irradiating wlth a laser beam having a wavelength of 355 nm
(triple frequency of an Nd:YAG laser, Quanta Ray DCR-2A, avallable
from Spectra Physics, USA). The pu130 duration is 6-8 ns and the
pul3e content 50 mJ and the beam i8 focussed through a glass lens
with a focal length of 250 mm to give a beam diameter of 1-2 mm. A
grey marking iB obtained.
Example 19: Marking is effected in accordance with Example 7~ but
irrsdiating with a laser beam having wavelength~ of 511 and 578 nm
of a copper vapour laser ~Plasma ~inetlcs 151, available from Plasma
KlneticA, USA). The pulse duration is 20-60 ns and the pulse content
is 0.5 mJ. Irradiation is made through a glass lens with a focal
length of 250 mm to give a beam diameter of 0.5-1 mm. A grey marking
with yellow etge is obtained at a beam diameter of 0.5 mm and a
yellow marklng at a beam diameter of 1 mm.
Example 2n: MarXing is effected in aocordance with ~xample 5, but
irradiating with a laser beam having wavelengths of 511 and 57~ nm
of a copper vapour laser (Plasma Kinetics 151 availabl~ from Plasma
Kinetics, USA~. The pulse duration is 20-60 ns and the pulse content
is 0.5 mJ. The beam is focussed through a glass lens with a focal
length of 250 mm to give a beam diameter of 0.5-1 mm. PBTP plates
are marked in grey wlth good contrAst.
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Example 21: Marking is effPcted in accordance with Example 2,
but lrradiating with a laser beam having wavelengths of 511 and
578 nm of a copper vapour laser (Plasma Kinetics 151 avallable from
Plasma Kinetics, USA). The pulse duration i9 20-60 ns and the pulae
content is 0.5 mJ. The beam is focussed through a gla~s lena with a
focal length of 250 ~m to give a beam diameter of 1-2 mm. PBTP
plates are marked in black.
Example 22: 10 parts of a PVC copolymer with a vinyl acetate content
of 10 % (Vinylite VYNS~, available from Union Carbide) ls stirred
into a mixture of solvents (77 parts of a 1:1 mixture of methyl
ethyl ketonelmethyl lsobutyl ketone and 10 parts of toluene) and
dissolved. Then 8 parts of a yellow azo condensation pigment
(Microlith~ Yellow 3G-R, ex Ciba-Geigy, base pigment C.I. Pigment
Yellow 93) are stirred in and subsequently dispersed in a dissolver
for 15 minutes at 6000 rpm. The resultant pigment disper~ion i~ used
as a printing ink for white pigmented soft PVC sheets containing
about 35 % of plasticlser. The sheets printed by rotogravure at
etching depths of 4, 8, 15, 28, 40 and 45 ~m are marked in grey with
good contrsst by the method described in Example la).
Example 23: 99.7 g of acrylic/butadiene styrene (Terluran~ 848S,
available from BASF, West Germany) are mixed with 0.3 g of a red
iron oxide pigment (Bayferrox~ 140, available frsm Bayer, C.I.
Pigment Red 101~ and the mixt~re i8 processed to small pla~es
measuring 4 x 5 cm (thickne~s 3 mm) in an in~ection moulding machtne
at a cylinder temperature of 200~-230C. These plates are irradiated
with an Nd:YAG pulsed laser in accordance with Example lb). A black
marking with good contrast i5 obtained.
Example 24: PBTP plat~s obtained in accordance with Example 2~ but
using 0.15 g of a copper phthalocyanine pigment (Mlcrolith~
Green G-FP, ex Ciba Geigy, Switzerland, base pig~ent C~Io Pigment
Green 7) a6 additive that effects a change in oolour, are marked
:
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- 18 -
black by the basic frequency (1064 nm) of an Nd:YAG laser (Quanta
Ray DCR-2A, available from Spectra Physics, USA~. The pulse
duration i9 6-8 ns and the pulse content 250 mJ.
Example 25: PBTP plate6 obtained according to Example 24, but
containing 0.3 g of Filester~ Yellow 2648A (anthraquinone deri~a-
tive, ex Ciba-Geigy, Switzerland, C.I. Pigment Yellow 147) as
addltive that effects a change in colour, are marked black with good
contrast. The pulse content is 500 mJ instead of 250 mJ.
Example 26: Following the procedure of Example 24, PBTP plates are
irradiated with a laser beam having wavelengths of 511 and 578 nm of
a copper vapour laser (Plasma Kinetics 151 available from Plasma
~inetlcs, USA). The pulse duration i9 20-60 ns and the pulse content
is 0.5 mJ. The beam is focussed through a glass lens with a focal
length of 250 mm to give a beam diameter of 0.5 mm and produces a
black marking.
Example 27: 99.7 g of polycarbonate tMa~rolan~ 2800, ex Bayer, West
Germany) are mixed with 0.3 g of a yellow cadmium pi~ment ~Cadmium
Yellow~ X-2822, ex Ciba-Geigy~ Switzerland, C.I. Pigment Yellow 35),
and the mixture is processed to small plates measuring 4 x 5 cm
(thickness 3 mm) in an injection moulding machine at a cylinder
temperature of 260-280C. These plates are irradiated with an
Nd:YAG pulsed laser in accordance with Example lb). A black marking
wlth good contrast is obtained.
Example 28: 99.7 g of polyoxymethylene ~Hostaform~ C 9020, a~ail-
able from Hoechst, West Germany) are mixed with 0~3 g of a yellow
pigment (Filester~ Yellow 2648 A, ex Cibs-Geigy~ Switzerland,
C.I. Pigment Yellow 147), and the mixture i~ processed to small
plates measuring 4 x 5 cm ~thickness 3 mm) in an inJectioD moulding
machine at a cylinder temperature of 190-210C. These plate~ are
irradia~ed with an Nd:YAG pulsed laser ln accordsnce wi~h
Example lb). A black marking with good contrast is obtained.
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- 19 -
Example 29: 99.7 g of HD polyethylene (Lupolen~ 1030 K, available
from ~ASF, West Germany) are mixed wlth 0.3 g of a red lron oxide
pigment (Bay~errox~ 140, available from Bayer, C.I. Pigment Red 101)
and the mixture is pro~ess~d to small plates measurlng 4 x 5 cm
(thickness 3 m~) in an injection moulding maohine at a cylinder
temperature of 190-230C. These plates are irradiated wlth an
Nd:YAG pulsed laser in accordance with Example lb). A black masking
with good contra~t is obtained.
Example 30: 99.7 g of polyamide 12 (Vestamid~ L 1901, available from
Chem. Werke Huls, West Germany) are mixed with 0.3 g of a yellow
anthraquinone pigment (Filester Yellow~ 2648 A, ex Ciba-Geigy,
Switzerland, C.I. Pigment Yellow 147), and the mixture i6 processed
to small plates measuring 4 x 5 cm (thickness 3 mm~ in an in~ection
moulding machine st a cylinder temperature of 210-250C. These
plates are irradiated with an Nd:YAG pulsed laser in accordance with
Example lb). A black marking with good contrast i9 obtained.
Example 31: 99.7 g of polyamide 66 (Ultramid~ A3K, available from
BASF, West Germany) are mixed with 0.3 g of a yellow anthraquinone
pigment (File~ter Yellow~ 2648 A, ex Ciba-Geigy, Switzerland,
C.I. Pigment Yellow 147), and the mixture is processed to small
plates measurlng 4 x 5 cm (thickness 3 mm) in a~ in~ection moulding
machine at a cylinder temperature of 250-280C. These plates are
irradiated with an Nd:YAG pulsed laser in acoordance with Example
lb~. A blsck marking with good contrast ia obtained.
Example 32: 100 g of polyvinyl chloride (Vestolite~S 6558, available
from Chem. Werke Huls, West Germany), 1.2 g of Irga~tab~ 17M
(butyltin sulfur stabiliser available from Ciba-Gelgy, Switzerland),
0.4 g of Irgawax~ 361 (lubr~cant, glycerol monooleate available from
Ciba-Geigy, Switzerland) and 0.2 g of Wax~ E (available from
Hoechst, West Germany) ars mixed with 0.3 g of a yello~ anthra-
quinone pigmont ~Filester Yellow~ 2648 A, e~ Ciba-Ceigy,
Switzerland, C.I. Pigment Yellow 147) and the mix~ure is rolled for
8 ~lnutes on a two-roll mill at a temperature of 160C. The coloured
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1 284~LZ5
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rigid PVC ~heet i~ stripped from the roller and pres~ed to plates
for 5 minutes at 160C on 8 multi-dayl~ght pres~. The plate~ 80
obtained are irradiated with an Nd:YAD pulsed laser in accordance
with Example lb). A black marking with good contrast i~ obtained.
Example 33: 99.7 g of polystyrene (Polystyrene~ 143 E, available
from BAS~, West Germany) are mlxed with 0.3 g of a red iron oxide
pigment (Bayferrox~ 140, available from Bayer, C.I. Pigment Red 101)
and the mixture i8 processed to ~all plate~ mea~uring 4 x 5 cm
(thickne~s 3 mm) in an injection moulding machlne at a cylinder
temperature of 200-~40C. Thsse plates are irradiated with an
Nd:YAG pulsed laser ln accordance with Example lb). A black marking
with good contrast i~ obtained.
Example 34: For colouring epoxy compositions, a colour paste i3
prepared from 85 g of basic epoxy re~in AY 105~ (ex Ciba-Geigy,
Switzerland), 1.5 g of a yellow azo condensation pigment (Cromo-
phtal Yellow~ 3G, C.I. Pigment Yellow 93~ and 13.5 g of a red azo
condensation pigment (Cromophtal Red~ G, C.I. Pigment Red 220, both
available from Ciba-Geigy, Switzerland). 1 8 of thi~ paste i~ mixed
with 24 g of an aliphatic amine HY 956~ ~ex Ciba-Geigy, Switzerland)
and 100 g of a basic epoxy resin AY 105~ (ex Ciba-Geigy, Switzer-
land) and cast to 1 mm plates. These plate~ are then cured for
3-4 hours at 40-50C. The plates are irradiated with a laser beam
in accordance with Example lb), except that the puls8 content is
1 mJ and the bea~ is focus~ed through a glass lens having a focal
length of 2S0 mm to give a beam diameter of 0.5 mm. The ~ark~ngs
obtained appear black when viewed normally in the direction of
viewing but have a tran~parent yellowish appearance when viewed
again~t a light ~ource.
Example 35: 65 g of ~tabili~ed polyvinyl chloride, 35 g of dioc~yl
phthalate and 0.2 g of 1,4-diketo-3,6-di-parachlorophenylpyrrolo-
3,4-c]pyrrole (according to US patent ~peclf~cation 4 415 685) are
stirred together and rolled for 7 minute~ at 160C Gn a ~wo-roll
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- 21 -
mill. The resultant red sheet is irradiated with an Nd:YAG pul~ed
laser in accordance with Example lb). A black marklng wlth good
contrast is obtalned.
Example 36: 99.7 g of melamine resin (Melopas~ N 37601, ~vailable
from Ciba-Geigy, Switzerland) are mixed with ~.3 g o~ a red iron
oxide pigment (Bayferrox~ 140, availablc from Bayer, C.I. Pigment
Red 101) and the mixture is processed to small plate~ measuring
4 x 5 cm (thickness 1-3 mm) in an injection moulding machine at a
cylinder temperature of 95C, 3 mould temperature of 170~C, and a
cycle of 35 seconds. These plates are irradiated with an Nd:YAG
pulsed la~er in accordance with Example lb). A grey marking with
good contrast i8 obtained.
Example 37: 98 g of polycarbonate granules (Lexan~ 101-111, avail-
able from General Electric Plastics BV, Holland) are mixed dry for
10 minutes with 0.25 g of a soluble anthraquinone dye ~Oracet~
Yellow GHS, ex Ciba-Geigy, Switzerland~ C.I. SolYent Yellow 163) and
1.5 g of T102 (type CL 220 ex Kronos Titan GmbH). The mixture is
moulded at 310C cylinder temperature and 80C mould te~perature by
injectiQn moulding, ground, and under the same conditlons ca~t to
plstes measuring 1.5 x 6.5 cm (thickness 1.5 mm~. The plates are
irradiated with a laser beam in accordance with Example lb) to give
black markings with good contra~t.
