1. Field of the invention.
[0001] The present invention relates to silver halide colour photographic film elements
having a thermoplastic support that are capable of being marked by means of a laser.
2. Background of the invention.
[0002] Well-known transparent film supports used for silver halide photographic projection
film elements or photographic film sheets to be examined as for e.g. colour print
film applications, can be e.g. cellulose triacetate, a polyester like a polyalkylene
terephthalate or naphthalate e.g. polyethylene terephthalate or polyethylene napthalate,
or polycarbonate.
[0003] As is further well-known, marking of such elements, before or after exposure to heat
or radiation can be performed by means of mechanical or chemical methods, by heat
or radiation, wherein said technique of radiation may be performed by means of a laser
beam, travelling over the zone of film that should be marked.
[0004] Marks added to a photographic film element may be e.g. graphic elements, characters,
bar codes or text.
[0005] Conventional chemical methods often make use of a technique wherein the surface of
the film is initially coated with a topcoat afterlayer, which is sensitive or made
sensitive to marking techniques by radiation, heat, etc. and wherein after etching
the marked zones, which behave differently from the non-marked ones, a washing process
cleans up the film element.
[0006] As is clear from this presentation huge amounts of chemicals are required and as
a consequence this inevitably causes environmental load. Moreover chemical methods
are rather complicated, as more steps are required, and as a consequence the said
chemical methods are penalised by the slowness of the treatment, the need to establish
artwork and the need to use plates of very high quality in order to get sharp marks.
Further aspects should not be neglected as there are: its sensitivity to the accuracy
with which various parameters should be adjusted such as the relief and the pressure
of the said plates, the problems of choosing reagents and of irregularities in adhesion
and in consistency of the protective layer, the need to take into account the sensitivity
and the detects of the element to be marked, the slowness and the instability of the
mechanical contact between the film element and the plate.
[0007] To summarise: chemical marking methods are much more complicated than e.g. laser
engraving methods. By means of a laser beam of a high energy laser, travelling along
a determined path corresponding to the inscriptions to be formed on the print film
element, the silver halide photographic emulsion present in the layer(s) coated onto
the support, becomes ablated locally.
[0008] In the particular application of laser subtitling methods of colour print films,
the quality of the result depends on the nature of the emulsion(s) and on the background
density of the images on which the subtitles are to be etched. Working parameters,
in particular the power of the laser beam radiation applied to the film and the displacement
speed of the laser beam, are determining the sharpness of the subtitles to a large
extent.
[0009] In said laser subtitling methods the power, the exposure time and the wavelength
are selected so as to destroy the photographic image forming emulsion elements completely
at points where the laser beam strikes the film. Due to the non-uniform release of
gelatinous residues, gelatin present as a main protective hydrophilic colloid in the
coated photographic layers, or to the damage of the support and as a result thereof
leaving dark spots and coloured spots, an unquiet and unpleasant enlarged view is
projected on the screen in the cinema.
[0010] A method and apparatus for subtitling colour multilayer motion pictures or photographic
plates by means of continuous or broken lines with a laser have been described in
EP-A 0 201 391.
Another method and apparatus makes use of a mask to produce subtitles and has been
described in EP-A 0 282 611.
Further EP-A 0 464 270 describes the application of a protective layer over at least
portions of a film or tape, whereupon characters should be written by means of a laser
beam.
[0011] An advanced environmental friendly system inscribes textures from a PC through the
support side of the film by means of a laser and has been described in DE 4 109 545:
a specific advantage herein is that no chemicals are used and that there is no waste
water at the end of the subtitling cycle.
[0012] An optimised method of subtitling motion pictures by laser beam travelling, directly
engraving a film element, has recently been disclosed in US-A 5,367,348. Said method
essentially comprises the steps of travelling the laser beam over the film at a speed
of displacement V lying in the range from about 1 to about 200 cm/s with a power of
the laser P lying in the range of about 100 mW to about 20 W, in order to have a ratio
V/P lying in the range from 10 to 30, followed by a washing step in order to remove
particles that have been heated and disclocated from the zones of the film that have
previously been marked by the low power laser beam. As has been disclosed in the said
US-Patent the method is well adapted to subtitle motion picture films on a support
constituted by a cellulose derivative such as cellulose triacetate, but is equally
applicable to film supports based on a thermoplastic polymer material, such as polyester.
However if use is made of a transparant polyester support such as e.g. polyethylene
terephthalate, it is not possible to obtain zones without undesired spots, resulting
in disturbing optical failures.
Moreover lowering of the power of the laser results in grayish or slightly yellow
coloured zones.
3. Objects of the invention.
[0013] It is an object of this invention to provide a silver halide colour photographic
film element coated on a transparent thermoplastic support showing no disturbing optical
failure after marking by means of a laser beam.
[0014] Particularly it is an object of this invention to provide a colour photographic motion
picture projection film element (print film element) coated on a transparent thermoplastic
support showing no disturbing optical failure after subtitling by means of a laser
beam.
4. Summary of the invention.
[0015] In order to reach the objects of this invention a silver halide colour photographic
film element is provided, comprising a transparent thermoplastic film support having
a subbing layer unit, coated thereon at least one colour forming hydrophilic layer
and protective layer, characterised in that at least said subbing layer unit comprises
at least one light-stabiliser, preferably absorbing ultraviolet radiation, and at
least one chemical compound having reducing properties. Said reducing properties are
defined in such a way that the sum of its polarographically determined anodic and
cathodic potentials is positive.
[0016] More particularly a colour motion picture projection film element, a so called colour
positive print film element is provided, comprising a transparent polyester film support
having a subbing layer unit, coated thereon in succession, a blue-sensitive silver
halide emulsion layer comprising a yellow-forming coupler, a red-sensitised silver
halide emulsion layer comprising a cyan-forming coupler, an intermediate layer, a
green-sensitised silver halide emulsion layer comprising a magenta-forming coupler,
and an antistress layer, characterised in that at least said subbing layer unit comprises
a chemical compound having reducing properties as defined above and/or a light-stabiliser,
preferably absorbing ultraviolet radiation.
5. Detailed description of the invention.
[0017] As described hereinbefore the problem is particularly encountered with photographic
film elements having thermoplastic supports with a polyester resin composition.
Thermoplastic polyesters are substantially composed of linear saturated polyester.
Preferred are homopolymers or copolymers having one recurring unit or at least two
different recurring units such as polyalkylene terephthalate or polyalkylene naphthalate.
[0018] Typical examples are butylene terephthalate, ethylene terephthalate, butylene naphthalene
dicarboxylate and ethylene naphthalene dicarboxylate, or mixtures of these. Examples
of the homopolymers are polybutylene terephthalate, polyethylene terephthalate, polybutylene
napthalene dicarboxylate, polyethylene napthalene dicarboxylate and mixtures thereof.
[0019] As is well-know from coating techniques applied to polyester supports it is preferred
to provide the transparent polyester film support with a primer coating or a subbing
layer before the application of further silver halide photographic emulsion layers.
An interesting primer coating for application between e.g. a polyethylene terephthalate
support and the said hydrophilic layers has been described e.g. in US-A 4,132,552.
Said primer coating, also called "subbing layer" is substantially composed of at least
one hydrophobic layer directly contacting the transparant film support and at least
one hydrophilic layer coated thereupon. The said subbing layer comprising at least
one hydrophobic polymer together with the adjacent hydrophilic layer coated thereupon
forms the "subbing layer unit" as set forth in the statement of this invention.
Preferred hydrophobic polymers used as subbing layers are styrene-butadiene copolymers,
vinylidene chloride copolymers, water-soluble polyesters and polyacrylic esters. From
these hydrophobic polymers styrene-butadiene copolymers and vinylidene chloride copolymers
are the most preferred. However it has been established that, according to this invention,
styrene-butadiene copolymers are the most preferred in order to find a solution for
the problem of getting laser marked zones on the film showing the fewest optical failures.
[0020] The hydrophilic layer coated adjacent to the subbing layer may be in the form of
an aqueous dispersion e.g. a latex, optionally containing a cross-linking agent, a
swelling agent, a matting agent or an antistatic agent. Examples of the cross-linking
agent include triazine compounds as described e.g. in US-A's 3,325,287; 3,288,775
and 3,549,377; dialdehyde compounds as described in US-A's 3,291,624 and 3,232,764;
epoxy compounds as described in US-A 3,091,537; vinyl compounds described in US-A
3,642,486; aziride compounds described in US-A 3,392,024; ethylene-imine compounds
described in US-A 3,549,378 and methylol compounds. Combinations of vinyl sulphonyl
compounds and triazine compounds may be useful and particularly the combination set
forth in US-A 4,680,257, wherein monochlorotriazine derivatives are preferred. According
to the present invention the said hydrophilic colloid layer (and the other hydrophilic
layers of the material) is(are) hardened with a vinyl sulphonyl hardener and/or with
a triazine hardener.
[0021] As a swelling agent present in the "subbing layer unit" hydrophilic colloids such
as dextran, polyacrylamide, polyvinylalcohol and polyvinyl pyrrolidone may be used,
but particularly preferred is gelatin, optionally in combination with at least one
of the other hydrophilic colloids cited.
Preferably hydrophilic layers are gelatinous layers. The gelatin used therein can
be lime-treated or acid-treated gelatin. The preparation of such gelatin types has
been described in e.g. "The Science and Technology of Gelatin", edited by A.G. Ward
and A. Courts, Academic Press 1977, page 295 and next pages. The gelatin can also
be an enzyme-treated gelatin as described in Bull. Soc. Sci. Phot. Japan, N° 16, page
30 (1966). Gelatine derivatives may be useful. Said derivatives have e.g. been described
in US-Patents 4,978,607; 5,378,598; 5,395,748 and 5,439,791 and in EP-A's 0 628 860
and 0 666 498.
[0022] As a matting agent present in the "subbing layer unit" use can be made of fine particles
of organic compounds such as polymethyl methacrylate homopolymer, copolymer of methyl
methacrylate with acrylic acid, starch and/or fine particles of inorganic compounds
such as colloidal silica, synthetic clay and titanium dioxide.
[0023] As an antistatic agent present in the "subbing layer unit" use can be made of metal
oxides, as described, e.g., in US-A's 4,394,441 and 5,439,785; of conductive polymers,
as described e.g. in US-A's 3,437,484 and 4,898,808; of fluoro-substuted compounds
as described e.g. in US-A's 4,407,937 and 4,366,238 or a combination thereof.
[0024] According to this invention at least said "subbing layer unit" defined above comprises
a chemical compound having reducing properties and/or a light-stabilising agent, also
called light-stabiliser, absorbing ultraviolet radiation. Both types of compounds
are mentioned as they compensate for or neutralise both an oxidation reaction which
takes place as a pure thermal process at a locally elevated temperature or with the
assistance of (laser) light respectively. In a preferred embodiment both types of
compounds are coated in the hydrophilic layer of the "subbing layer unit", coated
adjacent to the hydrophobic subbing layer which is in direct adhesive contact with
the support. The film element according to the present invention thus preferably comprises
said light-stabiliser and said chemical compound having reducing properties in the
said hydrophilic colloid layer: the other hydrophilic layers may simultaneously contain
one or more light-stabiliser(s) (which may e.g. also be present in the blue-sensitive
layer) and one or more chemical compound(s) having reducing properties (which is preferably
not present in light-sensitive emulsion layers comprising silver halide crystals,
as fog and instability may form a problem) or may contain one of more light-stabilizer
or one or more chemical compound(s) having reducing properties.
[0025] Reducing properties of the corresponding chemical compound having reducing properties
are derived from the sum of its polarographically determined anodic and cathodic potentials
which should be positive.
[0026] An overview of such compounds is given e.g. in "Plastic Additives Handbook", 3rd
Edition, 1990, Ed. by R. Gächter and H. Müller in Chapter 1, wherein antioxidants
have been described, and particularly in Chapter 12, wherein flame retardants have
been described. Another reference is found in "Ullmann's Encyclopedia of Industrial
Chemistry", Vol. A 20, p. 459.
[0027] To retard the thermal oxidation addition of anti-oxidants is the most commonly used
method of stabilisation. Especially preventive oxidants, also called secondary antioxidants,
that are responsible for the destruction of e.g. oxygen radicals, hydroxyl-radicals
and peroxy radicals generated rapidly in the presence of a sufficient amount of oxygen
at high temperatures, are particularly preferred.
[0028] Phosphites having the general formula O=P(OR)
3 with R being a substituted or unsubstituted alkyl or aryl group are the most well-known
typical representatives in the class of hydroperoxide decomposers, as well as organic
sulfides having the general formula R-S-R. With respect to having a negligible influence
on colour stability of the environment wherein the antioxidants are coated, before
and after laser marking, sterically hindered phenols are very useful compounds.
[0029] It is clear that the antioxidants should not decompose during different thermal attacks
of a polymer. Nevertheless at temperatures of up to 300°C and more parts of the oxidants
are consumed as a consequence of its protective function. Moreover it is important
to match the required amounts of antioxidants thereupon.
[0030] Specific classes of antioxidants are alkylphenols, hydroxyphenylpropionates, hydroxybenzyl
compounds, alkylidene bisphenols, secondary aromatic amines, thiobisphenols, aminophenols,
thioethers, phosphites and phosphonites, sterically hindered amines, etc.. Said products
are sold under well-known trade names as e.g. AGE RITE and VANOW, both from R.T. Vanderbilt
Co., Norwalk, USA; ANOX from Ente Nazionale Idrocarburi, Rome, Italy; AO from Song
Woun Ltd., Suweon, Korea; CAO from Ashland Chemical Co., Columbus, USA; CARSTAB from
Morton Thiokol, Cincinnati, USA; CYANOX from American Cyanamid Co., Wayne, USA; ETHANOX
from Ethyl Corporation, Baton Rouge, USA; GOOD-RITE from B.F. Goodrich Co., Cleveland,
USA; HOSTANOX from HOECHST, Frankfurt, Germany; IONOL and IONOX from Shell Nederland
Chemie BV, Den Haag, The Netherlands; IRGAFOS and IRGANOX from Ciba Geigy AG, Basel,
Switzerland; NONOX, TOPANOL and NEGONOX from ICI, London, GB; PERKANOX and PHOSCLERE
from Akzo Chemicals Nederland NV, Amsterdam, The Netherlands; SAMILIZER and ANTIGENE
from Sumimoto Chemical Co., Ltd., Osaka, Japan; SANTONOX, SANTOWHITE, SANTOFLEX, SANTICIZER
and FLECTOL from Monsanto Europe SA, Brussels, Belgium; VULKANOX from Bayer AG, Leverkusen,
Germany, etc., without however being limited thereto.
[0031] From the patent literature, well-known antioxidants have been described, e.g., in
US-A 5,427,997 and in DE 19502083.
[0033] A further type of useful compounds in order to reach the objects of this invention
is a so-called "flame retarding" agent.
[0034] If the layer unit adjacent to the thermoplastic support comprises one or more flame
retarding agents, its action is based on the formation of a "microshield" upon the
support in order to separate the combustible materials from oxygen, necessary for
the combustion process, which process is accelerated by heat, generated e.g. by laser
marking.
[0035] The surface of the support is thus cooled, smaller amounts of pyrolysis gases are
evolved, the oxygen necessary for the combustion process is excluded to a certain
extent and heat transfer is impeded. Typical useful compounds to reach that goal are
phosphorous compounds. The range of effectively working products containing phosphor
is extremely versatile and extends over several oxidation states: phosphines; phosphine
oxides, phosphonium compounds, phosphonates, elemental red phosphor, phosphites and
phosphates. Phosphorous compounds containing halogen, particularly bromine, have an
increased effectiveness as a flame retardant.
[0036] The effectiveness of flame retardants containing halogen atoms increases in the order
from fluorine to iodine.
As the C-F bond in such organic compounds is too strong and as the C-I bond is too
loose, compounds containing F and/or I are excluded. Compounds containing bromine
are preferred in comparison with those containing chlorine.
[0037] Typical classes of brominated flame retardants are
- (a) compounds with two benzene rings such as e.g. decabromodiphenyl ether, hexabromodiphenoxy
ethane etc.;
- (b) tetrabromophthalic anhydride and derivatives like e.g. tetrabromophthalate diols
and polyethers or ethylene bis(tetrabromophthalimide);
- (c) tetrabromobisphenol A (TBBA) and derivatives like e.g. TBBA-based epoxy resin,
TBBA-carbonate oligomer, TBBA-bis(allyl ether) etc.;
- (d) oligomeric and polymeric flame retardants like e.g. poly(pentabromobenzyl acrylate),
poly(dibromophenylene ether) or brominated polystyrene etc.;
- (e) aliphatic brominated compounds like e.g. hexabromocyclododecane; ethylene bis(dibromonorbornane-di-carboximide);
dibromoethyl dibromocyclohexane and dibromoneopentyl glycol etc..
[0038] Typical classes of chlorinated flame retardants are cycloaliphatic chlorinated flame
retardants like "dechlorane plus" and "HET-acid" and its anhydride. Aromatic chlorinated
compounds are not useful due to their limited flame retardancy.
[0039] Additions of antimony trioxide to the previously mentioned organic compounds produces
a synergistic effect in flame retardant action, thanks to the intermediary generated
SbOCl.
[0040] Further the list of useful inorganic compounds is rather limited: aluminum hydroxide
and boron containing compounds.
[0041] Specific flame retardant products sold under well-known trade names are e.g. SAYTEX
from Ethyl Corporation, Baton Rouge, USA; EXOLIT from HOECHST, Frankfurt, Germany;
REOFOS from Ciba Geigy Industrial Chemicals, Manchester, GB; CERECLOR from ICI, Cheshire,
GB; PHOSFLEX from Akzo Chemicals Nederland NV, Amsterdam, The Netherlands; PHOS-CHEK
from Monsanto Europe SA, Brussels, Belgium; DISFLAMOLL from Bayer AG, Leverkusen,
Germany, FIREBRAKE from U.S. Borax & Chemical Corp., Los Angeles, USA; IXOL from Kali-Chemie
AG, Hannover, Germany; SANDOFLAM from Sandoz AG, Basel, Switzerland; etc., without
however being limited thereto.
[0042] From the patent literature, especially phosphor containing compounds are preferred
as has been described e.g. in US-A 5,104,450 (arylene-bis(diaryl phosphates)), and
in US-A's 5,219,510 and 5,288,715 (non-volatile phosphoric acid ester).
Addition of antimony oxide or antimony-containing flame retardant aid has been disclosed
in US-A 4,666,965, wherein bromine-containing polymeric flame retarders having aromatic
rings have further been disclosed; and EP-A 0 485 181 respectively.
[0043] Flame retarders have also been described in US-Patents 5,071,912; 5,076,970; 5,081,176;
5,135,541; 5,218,021; 5,227,416; 5,238,982; 5,246,782; 5,326,805; 5,342,656; 5,346,938;
5,374,637; 5,389,712; 5,409,976 and 5,382,474, and in WO's 9411425; 9411439 and 9419382.
[0044] Light-stabilising agents, and more particularly those absorbing ultraviolet radiation
for linear or thermoplastic polyesters like polyethylene or polybutylene terephthalate,
show an absorption spectrum, which going from larger to smaller wavelengths begins
at 360 nm, significantly increases below 320 nm and becomes most pronounced below
300 nm.
[0045] Suitable light-stabilising agents absorbing ultraviolet radiation are selected from
the group of organic compounds consisting of 2-hydroxybenzophenones and 2-hydroxophenyl
benzotriazoles, sterically hindered amines (nitroxyl radicals as effectively absorbing
agent) and organic nickel compounds (like n-butylamine-nickel-2,2'-thio-bis-(4-t-octylphenolate)).
[0046] Well-known additives thereto are salicylates, cinnamate derivatives, resorcinol monobenzoates,
oxanilides and p-hydroxy-benzoates (like 3,5-di-tert.-butyl-4-hydroxybenzoic acid
2,4-di-tert.-butyl phenylester or 2-hydroxy-4-dodecyloxy-benzophenone). Benzotriazole
compounds are considered to act as quenchers, in the sense that they efficiently deactivate
excited states. UV-absorbers are further very effective decomposers of hydroperoxides
and scavengers of free radicals.
[0047] For linear polyesters benzotriazole type UV absorbers are generally chosen because
they inhibit low initial color and good color stability. Recently the effectiveness
of sterically hindered amines has been taken in consideration as opening new horizons.
[0048] Specific products sold under well-known trade names are e.g. HOSTAVIN from HOECHST,
Frankfurt, Germany; IRGASTAB, CHIMASSORB and TINUVIN from Ciba Geigy, Basel, Switzerland;
UVINIL and SICOSTAB from BASF, Ludwigshafen, Germany; UC-CHEK AM from Ferro Corp.,
Cleveland, USA; UV-ABSORBER BAYER from Bayer AG, Leverkusen, Germany; SANDUVOR from
Sandoz AG, Basel, Switzerland; GOODRITE UV, from BF Goodrich, Cleveland, USA; CYASORB
UV from American Cyanamid Co., Wayne, USA; EASTMAN INHIBITOR from Eastman Chemical
Products Inc., Kingsport, USA; RYLEX from Du Pont de Nemours, WILMINGTON, USA; SALOL
from Dow Chemical Co., Midland, USA; etc., without however being limited thereto.
[0049] Especially preferred concentrations of light stabilisers are in the range from 0.05
to 2 % by weight with respect to the layer or material to be protected.
[0050] Suitable UV-absorbers known from patent literature are e.g. aryl-substituted benzotriazole
compounds as described in US-A 3,533,794, 4-thiazolidone compounds as described in
US-A 3,314,794 and 3,352,681, benzophenone compounds as described in JP-A 2784/71
and US-A 3,503,330, cinnamic ester compounds as described in US-A 3,705,805 and 3,707,375,
butadiene compounds as described in US-A 4,045,229, butadiene compounds having a pyrrolidine
nucleus as has been disclosed in RD No. 18032 (April 1979), p. 139-140; benzoxazole
compounds as described in US-P 3,700,455 and polymeric stilbene-triazine compounds
as in US-P 3,615,547.
[0051] More particularly from said chemical compounds acting as UV-absorbers the following
chemical compounds were preferred in order to reach the objects of our invention:
- 2-OH-4-methoxy-benzophenone (compound II.1)

- 2,4-di-OH-benzophenone (compound II.2)

[0052] As set forth hereinbefore at least said subbing layer unit comprises a chemical compound
having reducing properties and/or a light-stabilising chemical compound absorbing
ultraviolet radiation.
[0053] Other layers in the layer arrangement of silver halide photographic film elements
according to this invention carrying a reducing agent and/or a light-stabilising agent
as set forth hereinbefore may be
- (a) radiation sensitive silver halide emulsion layers, the proviso that these agent(s)
has(have) no or a neglectable influence on sensitometric characteristics,
- (b) intermediate layers as e.g. layers between the "subbing unit" and the first light-sensitive
silver halide emulsion layer; between two light-sensitive silver halide emulsion layers,
between a light-sensitive layer and a protective overcoat layer (e.g. a protective
antistress layer)
- (c) protective layer(s)
- (d) overcoat layer(s)
- (e) afterlayer(s)
- (f) one or more backing layer(s).
[0054] In the case of hydrophilic colloid layers gelatin is the most preferred colloid.
[0055] According to this invention colour photographic motion picture projection film elements
as multilayer colour print film elements intended for making colour release prints
are subtitled after colour processing. Said elements basically consist of a transparent
polyester film support carrying in the given order a blue-sensitive silver halide
emulsion layer, a red-sensitised silver halide emulsion layer, and a green-sensitised
silver halide emulsion layer. Between the emulsion layers intermediate layers of a
hydrophilic colloid, mostly gelatin, are provided for better colour separation. The
side of the transparent film support opposite to that carrying the emulsion layers
is coated with a carbon black antihalation back layer. A carbon black antihalation
back layer indeed provides excellent halation protection and has excellent antistatic
properties. Unfortunately, carbon black has the disadvantage of getting loose easily
from the antihalation back layer, thus creating dust that smears the photographic
elements and exerts a disturbing influence during the imagewise exposure thereof.
Moreover, the removal of the carbon black antihalation back layer, which should take
place before the colour development can be started, is rather cumbersome. To avoid
the disadvantages concurrent with the use of carbon black antihalation back layers
in colour photographic motion picture projection film elements, one can make use in
a more preferred embodiment of antihalation dyes in these elements in the same way
as it is done in other types of photographic elements, in which one or several antihalation
dyes having light absorption spectra depending on the spectral sensitivity of the
light-sensitive layers are employed.
[0056] Attempts in colour photographic motion picture projection film elements in order
to use a combination of antihalation dyes, which can absorb light of the entire visible
spectral range, has been accomplished by providing a colour photographic motion picture
projection film element comprising a transparent film support and coated thereon in
succession, a blue-sensitive silver halide emulsion layer comprising a yellow-forming
coupler, an intermediate layer, a red-sensitised silver halide emulsion layer comprising
a cyan-forming coupler, an intermediate layer, a green-sensitised silver halide emulsion
layer comprising a magenta-forming coupler, and an antistress layer, characterised
in that between said support and said blue-sensitive silver halide emulsion layer
a yellow antihalation undercoat is provided, which comprises at least one yellow non-diffusing
dye that absorbs blue light and is removable and/or decolourisable in a processing
bath and that between said blue-sensitive silver halide emulsion layer and said red-sensitised
silver halide emulsion layer a bluish antihalation intermediate layer is provided,
which comprises at least one blue non-diffusing dye that absorbs red light and is
removable and/or decolourisable in a processing bath as has been disclosed in EP-Specification
0 252 550 and the corresponding US-Patent 4,770,984, which are incorporated herein
by reference.
[0057] Suitable amounts of both the ultraviolet light-absorbing compound and the reducing
agent are comprised between 25 and 250 mg/m
2 and more preferably between 50 and 150 mg/m
2.
[0058] According to a preferred embodiment according to this invention the said yellow antihalation
undercoat contains said at least one reducing agent and at least one light-stabiliser,
preferably in amounts as set forth hereinbefore. Dispersions of said reducing agent
and of said light-stabiliser in this hydrophilic yellow antihalation layer are preferably
prepared in the presence of oil-formers as e.g. tricresyl-phosphate, dibutylphthalate,
diethyllaurate, myristol, di-pentylphenol and the like. The type and the amounts of
oil-former used in the dispersion and coated therefrom in the "subbing layer unit",
preferably in the hydrophilic uppermost layer thereof, are decisive for the adhesion
characteristics of "subbing layer unit" and support.
[0059] As set forth hereinbefore bromine-containing agents are much better flame-retardant
or flame-resistant agents than chloride-containing agents. So it can be understood
that the use of silver halide emulsions rich in chloride, leads to a much larger extent
to a laser marking optical failure than the use of silver bromide or silver bromoiodide
emulsions, used preferably in e.g. colour negative films, microfilms, X-ray films
and the like. Materials in which silver halide emulsions rich in chloride are used
as e.g. colour print films, films for graphic applications and for diffusion transfer
are expected to be more sensitive to the phenomenon of flame-sensitivity, which causes
problems when laser engraving methods are applied to mark such films before processing.
It is clear however that in the particular case of subtitling colour print films according
to this invention the laser engraving method is applied after processing. Nevertheless
the presence of residual chloride ions, even after thoroughly washing procedures after
development, fixation and bleaching (as for colour films after being colour processed),
engraves the problem of flame-sensitivity to a large extent. This has been proved
by an experiment wherein a processed film was washed in a bath, containing an excess
of an alkaline chloride salt, followed by drying and laser engraving: the processed
film was much more sensitive to the known disturbing optical failures.
[0060] As has already been described in the background of this invention the power of the
laser is one of the factors determining the quality of the marks, obtained by laser
engraving techniques. Suitable lasers to be used, depending on the application are
gas-, dye- or semiconductor lasers emitting light in the wavelength ranges from ultraviolet
to infrared as well as a plasma light source. Said light sources are known as suitable
light sources for recording but in order to get subtitling action a "green-blue" YAG-laser
having a well-defined power and subtitling velocity, as e.g. described in US-A 5,367,348
is preferred. Another laser used in the Examples hereinafter is an Ar-laser, emitting
green-blue (488 nm) or, preferably, green (515 nm) light. Other lasers having a typical
emission in the longer (red) wavelength region are He-Ne and Kr-lasers.
6. EXAMPLES
[0061] Samples of colour photographic motion picture projection film elements A, B, C ....to
K were made. Each sample had a transparent film support, a subbing layer, a blue-sensitive
silver halide emulsion layer comprising a yellow-forming coupler, an intermediate
gelatin layer, a red-sensitised silver halide emulsion layer comprising a cyan-forming
coupler, an intermediate gelatin layer, a green-sensitised silver halide emulsion
layer comprising a magenta-forming coupler, and an antistress layer as has also been
described in EP-Specification 0 252 550. All samples were identical except for the
composition of the combination of reducing agent and light-stabiliser, as summarised
in Table 1.
[0062] Element A (comparative) had a yellow antihalation undercoat between the support and
the blue-sensitive emulsion layer, the yellow antihalation undercoat having a thickness
of 1 µm and comprising 290 mg of a yellow dye and 0.6 g of gelatin per m2.
[0063] Elements B, C .. to K (invention) had an identical yellow antihalation undercoat
as in Element A and in addition thereto the corresponding ultraviolet (UV) absorber
compound in an amount of 100 mg per m
2 and as a reducing agent in an amount of 100 mg per m
2, both UV-absorber and reducing agent as summarised in Table 1.
[0064] After exposure and colour processing the print film was subtitled by means of a laser
having a power of 6 W, 5 W and 4 W.
[0065] The colour motion picture film as well as still film pictures made therefrom were
projected and evaluated visually (qualitatively) on a projection screen. For all film
samples the results became better after inscription with the laser having a decreasing
power (4 W better than 5 W; 5 W better than 6W).
[0066] Differences between samples were about the same as the power of the laser was decreasing,
but as the global impression obtained was less noisy for a decreasing laser power,
results expressed as evaluation marks obtained after examining samples engraved with
a laser power of 4 W were summarised in Table 1 hereinafter.
[0067] Numbers of compounds are corresponding with those given in the detailed description.
[0068] Evaluation marks were given from 1 to 5:
1: excellent character type without noise
2: sligtly noisy, especially in overlapping parts of letters
3: noisy but still acceptable
4: noisy but unacceptable
5: very noisy, bad
Table 1
Exp. No. |
Reducing agent |
UV-absorber |
Laser Power |
Evaluation mark |
A |
No |
No |
4 W |
5 |
B |
I.4 |
II.1 |
4 W |
1 |
C |
I.5 |
II.1 |
4 W |
3 |
D |
I.1 |
II.1 |
4 W |
3 |
E |
I.2 |
II.1 |
4 W |
2 |
F |
I.3 |
II.1 |
4 W |
2 |
G |
I.4 |
II.2 |
4 W |
1 |
H |
I.5 |
II.2 |
4 W |
1 |
I |
I.1 |
II.2 |
4 W |
3 |
J |
I.2 |
II.2 |
4 W |
2 |
K |
I.3 |
II.2 |
4 W |
2 |
[0069] As can be concluded from the evaluation marks for the different coatings summarised
in Table 1 the disturbing optical failure, due to roughness on the bare support, obtained
after the destructive thermic and thermo-oxidative engraving processes due to the
laser subtitling method has been overcome as soon as a suitable combination of UV-absorber
and reducing agent has been added to the hydrophilic yellow antihalation layer, said
layer making part of the "subbing layer unit" as described hereinbefore. Especially
preferred therein is the combination of reducing compound I.4 together with ultraviolet
absorber II.1 or II.2, as well as the combination of reducing compound I.5 with ultraviolet
absorber II.2.
[0070] All other combinations lead to improvements if compared with the comparative sample
A, wherein none of both types of compounds are added.
[0071] Further experiments wherein amounts of 100 mg/m
2 of both an antioxidant and an ultraviolet absorbing compound were divided between
the yellow antihalation layer, the blue antihalation layer and/or the protective antistress
layer were showing that addition of both compounds to gelatinous intermediate or topcoat
layers situated farther from the support lead to less convincing or less pronounced
improvements in the quality of laser engraved characters.
1. A silver halide colour photographic film element comprising a transparent thermoplastic
film support having a subbing layer unit, coated thereon at least one colour forming
hydrophilic layer and protective layer, characterised in that at least said subbing
layer unit comprises at least one light-stabiliser and at least one chemical compound
having reducing properties.
2. A film element according to claim 1, wherein said chemical compound having reducing
properties is characterised by the property that the sum of its polarographically
determined anodic and cathodic potentials is positive.
3. A film element according to claim 1, wherein said light-stabiliser is a compound absorbing
ultraviolet radiation.
4. A film element according to any of claims 1 to 3, wherein said element is a colour
photographic motion picture projection film element comprising a transparent film
support having a subbing layer unit and coated thereon in succession, a blue-sensitive
silver halide emulsion layer comprising a yellow-forming coupler, an intermediate
layer, a red-sensitised silver halide emulsion layer comprising a cyan-forming coupler,
an intermediate layer, a green-sensitised silver halide emulsion layer comprising
a magenta-forming coupler, and an antistress layer.
5. A film element according to claim 4, wherein said intermediate layer coated between
the blue-sensitive silver halide emulsion layer and the transparant support a yellow
antihalation undercoat is present, which comprises at least one yellow non-diffusing
dye that absorbs blue light and is removable and/or decolourisable in a processing
bath.
6. A film element according to claim 4 or 5, wherein between said blue-sensitive silver
halide emulsion layer and said red-sensitised silver halide emulsion layer a bluish
antihalation intermediate layer is provided, which comprises at least one blue non-diffusing
dye that absorbs red light and is removable and/or decolourisable in a processing
bath.
7. A film element according to any of claims 1 to 6, wherein said transparent thermoplastic
film support has a polyethylene terephthalate support.
8. A film element according to any of claims 1 to 7, wherein said chemical compound is
an antioxidant and/or a flame retarding agent selected from the group of compounds
consisting of a phosphite compound, an aminophenol compound, an alkylphenol compound,
a di-ester of di-t-butylphenol compound and a 2,5-dialkylester substituted hydroquinone
compound.
9. A film element according to any of claims 3 to 8, wherein said light-stabilising agent
absorbing ultraviolet radiation is selected from the group of agents consisting of
aryl-substituted benzotriazole compounds, 4-thiazolidone compounds, benzophenone compounds,
cinnamic ester compounds, butadiene compounds, benzoxazole compounds and polymeric
stilbene-triazine compounds.
10. A film element according to any of claims 3 to 8, wherein said light-stabilising agent
absorbing ultraviolet radiation is selected from the group of benzophenone compounds
consisting of 2-hydroxy-4-methoxy-benzophenone and 2,4-dihydroxy-benzophenone.
11. A film element according to any of claims 1 to 10, wherein said subbing layer unit
is substantially composed of at least one hydrophobic layer directly contacting the
transparant film support and at least one hydrophilic colloid layer coated thereupon.
12. A film element according to claim 11, wherein said hydrophobic layer has a composition
selected from the group consisting of vinylidene chloride and styrene/butadiene copolymers.
13. A film element according to claim 11 or 12, wherein said hydrophilic colloid layer
is a gelatinous layer.
14. A film element according to any of claims 11 to 13, wherein said hydrophilic colloid
layer is hardened with a vinyl sulphonyl hardener and/or with a triazine hardener.
15. A film element according to any of claims 11 to 14, wherein said hydrophilic colloid
layer comprises said light-stabiliser and said chemical compound having reducing properties.