WO2009009066A1 - Composition de revêtement permettant de former un matériau ayant une stabilité à la chaleur et à l'humidité et qui peut être marquée par un laser - Google Patents

Composition de revêtement permettant de former un matériau ayant une stabilité à la chaleur et à l'humidité et qui peut être marquée par un laser Download PDF

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Publication number
WO2009009066A1
WO2009009066A1 PCT/US2008/008416 US2008008416W WO2009009066A1 WO 2009009066 A1 WO2009009066 A1 WO 2009009066A1 US 2008008416 W US2008008416 W US 2008008416W WO 2009009066 A1 WO2009009066 A1 WO 2009009066A1
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Prior art keywords
coating composition
laser markable
polyurethane
binder
laser
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PCT/US2008/008416
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English (en)
Inventor
Hai-Xing Wan
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Fujifilm Hunt Chemicals USA Inc
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Fujifilm Hunt Chemicals USA Inc
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/02—Emulsion paints including aerosols
    • C09D5/024—Emulsion paints including aerosols characterised by the additives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/41—Organic pigments; Organic dyes

Definitions

  • Laser beam marking is a growing area of great interest that can offer a clear advantage over conventional marking technologies in terms of marking speed, as well as the additional features of environmental friendliness, safety, and minimal maintenance.
  • the principle of laser marking is that the laser beam is absorbed by heat sensitive materials and is converted to heat. Subsequently the heat sensitive material reacts to the heat to form a mark.
  • One widely used laser marking method in industry is laser ablation.
  • a key disadvantage of laser ablation is that it requires strong interaction of the marking substrate with the laser beam to yield significant color or density changes over unmarked area.
  • packaging materials such as plastic films or containers and glass bottles, do not have sufficient interaction with the laser beam, the interaction does not yield significant contrast change on the material, or the interaction causes damages to the substrate surface.
  • the laser markable coating composition generally can contain color forming agents which include inorganic and organic pigments and dyes, as well as binders and other coating composition additives such as surfactants, plasticizers, antifoaming agents, ultraviolet radiation absorbers, sensitizers, and other compounds know to the art.
  • the binder used in a liquid coating composition is generally a natural or synthetic resin that has the major function of a film former.
  • Binders that function as a film forming agent in a laser markable coating composition are known in the art and are described in many patents, for example US 5608429, US 5691757, and US 6210472.
  • binder resins have been used to obtain special effects in a laser markable coating composition.
  • a coating composition is described which is free of dye or pigment compounds and which can generate white marks after being exposed to the laser beam.
  • the binder resin not only is the binder resin a film former, but also a heat responsive material used to form a mark.
  • US 613342 describes a coating composition that contains a combination of an opaque mix of resin and colorant. After receiving the exposure by a laser beam, the opacity of the resin fades and the color from the colorant becomes visible.
  • the resins claimed in this patent have the dual functions of film forming and color masking.
  • the binder in a laser markable coating composition can function to form special effect marks, this same effect of forming a white mark can be a severe disadvantage, having an adverse effect that contributes to poor mark quality when used with a laser markable coating composition that contains color forming agents.
  • low mark density and poor color purity is produced when a laser markable material is marked with a CO 2 laser when the laser markable coating composition contains a polyvinyl alcohol as the binder resin in combination with black color forming agents.
  • An opaque white mark is generated after being exposed with a CO 2 laser.
  • the white mark generated by the binder resin combines with the desired mark color given by the incorporated color forming agents to cause a lower mark density and reduced color purity on the marked region of the laser markable material.
  • WO 2006/063165 A2 One solution to solve this problem has been provided in WO 2006/063165 A2. It claims that a substituted or unsubstituted polyurethane compound can be used as the binder in the laser markable coating composition to promote improved mark density. While use of a laser markable coating composition containing polyurethane as a binder can provide the benefit of producing marks of higher density as provided in WO 2006/063165 A2, it has been found that these binder resins initiated an unexpected reaction between the color formation agents, and generated stain when the coated material was stored in a hot and/or humid environment. Unfortunately, many packaged goods can be exposed to hot and/or humid conditions when being handled, transported, and stored. When this stain formation occurs, laser markable coatings will be of only limited use in the product and package labeling industry.
  • the resin provides a media for suspending the color formation agents and other ingredients as well as being chemically and physically inert. This chemical and physical inertness can be effective to reduce or prevent unwanted white or opaque marks as well as minimize color formation reaction of the color forming agent. Minimizing the unwanted color formation reaction can provide reduced stain on the coated material which can be produced during storage in a hot and/or humid environment.
  • a laser markable coating composition comprising a binder resin which is commercially available in the market and inert to color formation.
  • the selected binder resin will not physically nor chemically affect the color forming system - an electron donor type of dye precursor and an electron acceptor type of developer.
  • a stain free background of the laser markable material can be obtained.
  • a laser markable material is provided comprising a color forming layer and assistant layers such as a protective layer in which the selected binder resin will not adversely affect the color formation agents in the laser markable layer to obtain a stain-free background for the laser markable material under a hot and/or humid condition.
  • binder resins are known in the art which can be selected for use as a binder in a coating composition of laser markable material.
  • useful binder resins include starch and modified derivatives, cellulose and modified derivatives, gelatin, casein, gum arabic, pectin, sodium alginate, silicate resin, polyvinyl alcohol, polyacrylic resin, epoxy, polystyrene, polyester, polyacrylic amide, styrene-acrylic acid copolymer, styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, styrene-maleic anhydride copolymer, ethylene- maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, polyvinyl pyrrolidone, ethylene-acrylic acid copolymer, vinyl acetate-acrylic acid copolymer, and others known in the art.
  • these resins polyvinyl alcohol, gelatin,
  • polyurethane and its derivatives are know in the art to be ideal compounds.
  • compounds claimed in WO 2006/063165 A2 include Macekote 9525 and Alberdingk U400N which are polyether-based polyurethanes, Alberdingk U2101VP which is a polyester-based polyurethane, Alberdingk U9152VP which is a polycarbonate-based polyurethane, and Alberdingk CUR21 , a castor oil-based polyurethane.
  • a laser markable material containing these binders can easily generated stain in a hot and/or humid environment.
  • the stain may be caused by an unexpected reaction between the binder and color formation agents which are suspended in the binders.
  • waterborne, solvent-free polyurethane emulsion, suspension, or dispersion as the binder in an exemplary laser markable coating composition which comprise color formation agents generates minimal stain under hot and/or humid storage conditions.
  • These waterborne, solvent-free polyurethane compounds offer similar CO 2 laser inertness to that of polyurethanes claimed in WO 2006/063165 A2. More importantly, minimal stain increase is achieved when the laser markable material is stored under hot and/or humid storage conditions. This offers a clear advantage over the prior art binders.
  • the definition for "waterborne, solvent-free polyurethane compounds” are those polyurethane compounds that do not contain organic solvents and which contain only water or other inorganic compounds as the solvent to form an emulsion, suspension, or dispersion.
  • waterborne, solvent-free polyurethane or modified derivatives are emulsions, suspensions, or dispersions of polyester-based polyurethane, polyether-based polyurethane, polycarbonate-based polyurethane, castor oil-based polyurethane, or any combinations thereof.
  • Laser markable coating composition containing waterborne, solvent-free polyurethane as a binder
  • a laser markable coating composition comprising the exemplary waterborne, solvent-free polyurethane as binder can also comprise color-forming agents and auxiliary additives.
  • the exemplary color-forming agent is a colorless compound that becomes colored after the laser-facilitated reaction with another compound in the coating composition.
  • the color-forming agent can also include a compound having a primary color that further changes color after reacting with another compound in a laser-marked material.
  • a preferred example of color forming agents is a pair consisting of an electron donor-type dye precursor and an electron acceptor-type developer. This pair of colorless compounds reacts with each other to produce colored compound.
  • Examples of the electron donor-type dye precursor include a triphenylmethane phthalide series compound, a fluorane series compound, a phenothiazine series compound, an indolyl phthalide series compound, a leucoauramine series compound, a rhodamine lactam series compound, a triphenylmethane series compound, a triazene series compound, a spiropyran series compound, a fluorene series compound, a pyridine series compound, and a pyradine series compound.
  • a triphenylmethane phthalide series compound a fluorane series compound, a phenothiazine series compound, an indolyl phthalide series compound, a leucoauramine series compound, a rhodamine lactam series compound, a triphenylmethane series compound, a triazene series compound, a spiropyran series compound, a fluorene series
  • Examples of the electron acceptor-type compound, which reacts with the electron donor-type dye precursor include an acidic substance, such as activated bentonite, metal salt of salicylate, phenol compound, organic acid or its metallic salt, oxybenzoate, and others known in the art.
  • an acidic substance such as activated bentonite, metal salt of salicylate, phenol compound, organic acid or its metallic salt, oxybenzoate, and others known in the art.
  • the auxiliary additives which can be incorporated into the coating composition can include: known coating additives, such as surfactants, anti-foam agents, plasticizers, rheological agents, biocides, antistatic agents, solvents, photoinitiator for radiation curing, and other compounds known in the art, additives for enhanced laser marking performance, such as heat transfer agents, melting agents, ultraviolet ray absorbing agents, antioxidants, as well as other compounds know in the art.
  • Heat transfer agents absorb CO 2 laser emission at 943 cm "1 and convert it to heat. Examples can include mica, fumed silica, fumed alumina, and inorganic or organic compounds that have strong absorption in the range of 900 cm '1 to 1000 cm "1 .
  • Melting agents may be contained in the laser- sensitive recording layer of the laser markable material in order to improve the laser responsiveness.
  • Examples can include aromatic ether, thioether, ester.aliphatic amide, ureide, and other compounds know in the art.
  • Ultraviolet ray absorbing agents include a benzophenone series ultraviolet ray absorbing agent, a benzotriazole series ultraviolet ray absorbing agent a salicylic acid series ultraviolet ray absorbing agent, a cyanoacrylate series ultraviolet ray absorbing agent, and an oxalic acid anilide series ultraviolet ray absorbing agent.
  • Antioxidants include a hindered amine series antioxidant, a hindered phenol series antioxidant, an aniline series antioxidant and a quinoline series antioxidant, and other compounds know in the art.
  • One or more water-soluble resins which comprise the binder in the coating composition which also comprise the above-described color forming agents and auxiliary additives can be appropriately selected from a solvent-free polyurethane or its modified derivatives, such as the emulsion, suspension, or dispersion of polyester-based polyurethane, polyether-based polyurethane, polycarbonate- based polyurethane, castor oil-based polyurethane, or any combinations thereof.
  • the emulsion, suspension, and dispersion of these polyurethane compounds must be waterborne and solvent-free.
  • a combination of the polyurethane compounds and other types of resins that are inert to the color forming agents in the laser markable coating composition can be used to form a liquid laser markable coating composition depending on necessity.
  • the concentration of binder can be from about 0.1% to about 60%, more preferably from about 1 % to about 50% and most preferably from about 2% to about 40%,
  • the laser markable coating composition can be formulated as a single part composition that contains all color forming agents and necessary auxiliary additives. Alternately the laser markable coating composition can be designed to have multiple parts to obtain increased storage stability before being mixed and coated onto a substrate.
  • a preferred embodiment for the binder compounds is the capability to be incorporated into any of the parts of the laser markable coating composition. Waterborne and/or solvent-free polyurethane and modified derivatives have been found to meet this requirement.
  • Laser markable coating composition containing microencapsulated dye and the solvent- free polyurethane binder In order to obtain high mark density, the electron donor-type dye precursor in a laser markable coating composition containing microencapsulated dye and the solvent- free polyurethane binder preferably exists in a high concentration in the microcapsules.
  • the compounds represented by general structural formula 1 are preferable because these can be incorporated into the microcapsules in very high concentration and can provide high mark density.
  • Ri and R 2 represent an alkyl group, such as a butyl group, a sec-butyl group, a ferf.-butyl group, a propyl group, an ethyl group, a methyl group;
  • R 3 represents a hydrogen, or an alkyl group, such as a butyl group, a sec. -butyl group, a terf.-butyl group, a propyl group, an ethyl group, a methyl group;
  • R 4 represents an imino-benzene group or a hydrogen.
  • a preferable embodiment is that the solubility of the said electron donor-type dye precursor is higher than about 10g/100g of ethyl acetate, more preferably is higher than about 15 g/100 g of ethyl acetate, and most preferably is higher than about 18 g/100 g of ethyl acetate.
  • the most preferable compound (Formula 2) is shown as below: Formula 2
  • a preferable embodiment is that more than about 80% by weight of the electron donor-type dye precursors are of the compounds represented by structural formula 1 , and a more preferable embodiment is that more than about 90% by weight are the said compound and a most preferable embodiment is that about 100% by weight are the said compound.
  • the color forming agents into a laser markable coating composition.
  • Several examples to incorporate the color forming agents are by dispersing the solid powder of color forming agents into the binder medium, dissolving the color forming agents in a solvent and add the solution of color forming agents into the binder medium, and microencapsulating the color forming agents and dispersing the encapsulated color forming agents into the binder medium.
  • a preferred method is micro-encapsulating the color forming agents and dispersing the encapsulated color forming agents into the binder medium.
  • the color forming agents are protected and a chemically stable coating composition can be achieved producing minimal color stain, especially under the storage conditions of high heat and/or humidity.
  • Preferred color forming agents comprising the laser markable coating composition are a pair of electron donor-type dye precursor and an electron acceptor-type developer.
  • either the dye precursor or the developer or both can be micro-encapsulated. It is preferred that electron- donor type dye precursor is micro-encapsulated.
  • a surface polymerization process is particularly preferably employed, such that the electron donor-type dye precursor that becomes a core of the microcapsules is dissolved or dispersed in a hydrophobic organic solvent to prepare an oily phase, which is then mixed with an aqueous phase obtained by dissolving a water-soluble polymer in water, and is then subjected to emulsification and dispersion by using, for example, an homogenizer, followed by heating, so as to conduct a polymer-forming reaction at the interface of the oily droplets, whereby a microcapsule wall of a polymer substance is formed.
  • the reactants for forming the polymer substance are added to the interior of the oily droplets and/or the exterior of the oily droplets.
  • Specific examples of the polymer substance include polyurethane, polyurea, polyamide, polyester, polycarbonate, a urea-formaldehyde resin, a melamine resin.
  • polyurethane, polyurea, polyamide, polyester and polycarbonate are preferred, and polyurethane and polyurea are particularly preferred.
  • the microcapsule wall can be easily formed by reacting a polyisocyanate, such as diisocyanate, triisocyanate, tetraisocyanate or a polyisocyanate prepolymer, with a polyamine, such as diamine, triamine or tetramine, a prepolymer having two or more amino groups, piperazine or a derivative thereof, or a polyol, in the aqueous phase by the interface polymerization process.
  • a polyisocyanate such as diisocyanate, triisocyanate, tetraisocyanate or a polyisocyanate prepolymer
  • a composite wall formed with polyurea and polyamide or a composite wall formed with polyurethane and polyamide can be prepared in such a manner that, for example, a polyisocyanate and a secondary substance for forming the capsule wall through reaction therewith (for example, an acid chloride, a polyamine or a polyol) are mixed with an aqueous solution of a water-soluble polymer (aqueous phase) or an oily medium to be encapsulated (oily phase), and subjected to emulsification and dispersion, followed by heating.
  • a polyisocyanate and a secondary substance for forming the capsule wall through reaction therewith for example, an acid chloride, a polyamine or a polyol
  • aqueous phase water-soluble polymer
  • oily medium to be encapsulated oily medium to be encapsulated
  • polyisocyanate compound a compound having an isocyanate group of three or more functional groups is preferred, and a difunctional isocyanate compound may be used in combination therewith.
  • a diisocyanate such as xylene diisocyanate or a hydrogenated product thereof, hexamethylene diisocyanate or a hydrogenated product thereof, tolylene diisocyanate or a hydrogenated product thereof and isophorone diisocyanate, as the main component; a dimer or a trimer thereof (burette or isocyanaurate); a compound having polyfunctionality as an adduct product of a polyol, such as trimethylolpropane, and a difunctional isocyanate, such as xylylene diisocyanate; a compound of an adduct product of a polyol, such as trimethylolpropane, and a difunctional isocyanate, such as xylylene diisocyanate, having a polymer compound, such as polyether having an active hydrogen, such as polyoxyethylene oxide, introduced therein; and a formalin condensation product of benzeneisocyanate.
  • a diisocyanate such as
  • the compounds described in JP-A-62-212190, JP-A-4-26189, JP-A-5-317694 and Japanese Patent Application No. 8-268721 are preferably used.
  • Specific examples of the polyol and/or the polyamine added to the aqueous phase and/or the oily phase as one constitutional component of the microcapsule wall through the reaction with the polyisocyanate include propylene glycol, glycerin, trimethylolpropane, triethanolamine, sorbitol and hexamethylenediamine. In the case where a polyol is added, a polyurethane wall is formed.
  • conditions for the microencapsulation reaction are set so that at least about 90% of the total volume of said dye precursor particles have an average particle diameter of the microcapsules that are formed of between about 0.3 to about 12 ⁇ m, preferably between about 0.2 ⁇ m and about 5 ⁇ m, and most preferably between about 0.2 ⁇ m and about 2 ⁇ m, the thickness of the microcapsule wall is preferably between about 0.01 ⁇ m and about 0.3 ⁇ m.
  • the microencapsulation reaction is also controlled so that the microcapsule wall has a Tg of from about 150 ° C to about 190 0 C 1 preferable from about 160 0 C to about 180°C, and most preferably from about 165 ° C to about 175 0 C.
  • reaction conditions for microcapsule preparation. These conditions include emulsification process of the electron donor-type dye precursor, addition rates and amounts of the polyisocyanate and polyamine to form the microcapsule wall, as well as mixing and reaction temperature, time, and agitation. In the reaction, it is preferred to increase the reaction rate by either maintaining a high reaction temperature or by adding an appropriate polymerization catalyst.
  • Particle size of the microcapsules in the suspension can be measured by diluting the suspension into aqueous solution and using laser scattering method based on Mie-scattering theory to measure the particle size and distribution.
  • Typical equipment used for such measurement is Horiba's LA series, Beckman Coulter's LS series or Malvern Instruments' Mastersizer series.
  • the T g of the microcapsule wall can be measured by using conventional differential thermal analysis methods, such as DSC (Differential Scanning Calorimeters) or DDSC (Dynamic DSC) 1 which measures specific heat (C p ) change over different temperature ranges.
  • DSC Different Scanning Calorimeters
  • DDSC Dynamic DSC 1 which measures specific heat (C p ) change over different temperature ranges.
  • Both a microcapsule-containing suspension and a blank suspension should be placed in the sample trays before measurement.
  • Typical equipment used for such measurements are Perkin Elmer Diamond DSC, Sapphire DSC, HyperDSCTM
  • the microcapsule wall may further contain, depending on necessity, a metal- containing dye, a charge adjusting agent, such as nigrosin, and other arbitrary additive substances. These additives may be contained in the capsule wall during wall formation or at other arbitrary times as required.
  • a monomer such as a vinyl monomer, may be graft-polymerized depending on necessity.
  • plasticizer that is suitable for the polymer that is used as the wall material.
  • the plasticizer preferably has a melting point of about 5O 0 C or more, and more preferably of about 12O 0 C or more.
  • plasticizers those in a solid state at ordinary temperature can be preferably selected.
  • the wall material comprises polyurea or polyurethane
  • a plasticizer a hydroxyl compound, a carbamate compound, an aromatic alkoxy compound, an organic sulfoneamide compound, an aliphatic amide compound, and an arylamide compound are preferably used.
  • an organic solvent having a boiling point of from about 100 to about 300 0 C is preferred.
  • an organic solvent having a boiling point of from about 100 to about 300 0 C is preferred.
  • Specific examples thereof include an ester compound, dimethylnaphthalene, diethylnaphthalene, diisopropylnaphthalene, dimethylbiphenyl, diisopropyldiphenyl, diisobutylbiphenyl, 1-methyl-1-dimethylphenyl-2- phenylmethane, 1 -ethyl-1 -dimethylphenyl-1 -phenylmethane, 1 -propyl-1 - dimethylphenyl-1 -phenylmethane, triarylmethane (such as tritoluylmethane or toluyldiphenylmethane), a terphenyl compound (such as terphenyl), an alkyl compound, an organic solvent having a boiling point of from about 100 to
  • ester compound examples include a phosphate, such as triphenyl phosphate, tricresyl phosphate, butyl phosphate, octyl phosphate or cresylphenyl phosphate; a phthalate, such as dibutyl phthalate, 2-ethylhexyl phthalate, ethyl phthalate, octyl phthalate or butylbenzyl phthalate; dioctyl tetrahydrophthalate; a benzoate, such as ethyl benzoate, propyl benzoate, butyl benzoate, isopentyl benzoate or benzyl benzoate; an abietate, such as ethyl abietate or benzyl abietate; dioctyl adipate; isodecyl succinate; dioctyl azelate; an oxalate, such as dibutyl o
  • hydrophobic organic solvents may be used alone or in combinations of two or more.
  • tricresyl phosphate is preferably used, either singly or as a mixture with other solvents since it provides high emulsion stability.
  • a low boiling point solvent having high solubility may additionally be used in combination.
  • Preferred examples of the low boiling point solvent include ethyl acetate, isopropyl acetate, butyl acetate, and methylene chloride.
  • the content of the electron donor-type dye precursor is preferably from about 0.1 to about 5.0 g/m 2 , and more preferably from about 1.0 to about 4.0 g/m 2 .
  • the content of the electron donor-type dye precursor is in the range of from about 0.1 to 5.0 g/m 2 , a sufficient coloring density can be obtained, and when the content is 5.0 g/m 2 or less, both a sufficient coloring density can be achieved while the transparency of the laser-sensitive recording layer can also be maintained.
  • water-soluble resins are added to the aqueous phase of the reaction mixture as a binder in order to stabilize the emulsified dispersion and formed microcapsules, and the type and the addition amount of the water-soluble resins are selected so that the viscosity of the coating composition has a viscosity of from about 5 centipoise (cP) to about 30 cP, preferably from about 10 cP to about 25 cP, and most preferably from about 10 cP to about 20 cP. Viscosity is measured using Brookfield Programmable DV-II+ viscometer with small sample adapter plus a S21 spindle at 100-200 RPM. Regular RV series spindle may also be used depending on sample quantity.
  • cP centipoise
  • Viscosity is measured using Brookfield Programmable DV-II+ viscometer with small sample adapter plus a S21 spindle at 100-200 RPM. Regular RV series spindle may also be used depending on sample quantity.
  • the water-soluble resin composition used as the binder for microcapsule formation of the electron-donor dye precursor can also be appropriately selected from compounds which can include solvent free polyurethane or its modified derivatives, such as the emulsion, suspension, or dispersion of polyester based polyurethane, polyether based polyurethane, polycarbonate based polyurethane, castor oil based polyurethane, or any combinations thereof. It is preferred that about at least 50% or more of the total binder solid weight comprising the electron-donor dye precursor microcapsule is the waterborne and/or solvent-free polyurethane and modified derivatives.
  • the mixing ratio of the oily phase to the aqueous phase is preferably from about 0.02 to about 0.6, and more preferably from about 0.1 to about 0.4.
  • the mixing ratio is in the range of from 0.02 to 0.6, a suitable viscosity can be maintained. This provides both an improved productivity of use for coating the composition as well as optimized stability of the coating composition.
  • a surfactant may be added to at least one of the oily phase and the aqueous phase.
  • the surfactant a known surfactant for emulsification may be used.
  • the addition amount of the surfactant preferably from about 0.1 % to about 5%, and more preferably from about 0.5 to about 2%, based on the weight of the oily phase.
  • the surfactant contained in the aqueous phase one that does not cause precipitation or aggregation through an action with the binder can be used by appropriately selecting from anionic and nonionic surfactants.
  • the surface-active agent include sodium alkylbenzenesulfonate, sodium alkylsulfate, sodium dioctyl sulfosuccinate and a polyalkylene glycol (such as polyoxyethylene nonylphenyl ether).
  • the emulsification can be easily conducted by subjecting the oily phase containing the foregoing components and the aqueous phase containing the binder and the surfactant to a means that is generally used for fine particle emulsification, such as high speed agitation or ultrasonic wave dispersion by using a known emulsifying apparatus, such as a homogenizer, Manton
  • Gaulin an ultrasonic wave disperser, a dissolver or a KADY mill.
  • the emulsion is heated to a temperature of from 30 to 70° C for accelerating the capsule wall-forming reaction.
  • water is added to the emulsion to decrease the probability of collision of the capsules or that sufficient agitation is conducted to prevent aggregation of the capsules.
  • a dispersion, emulsion, or suspension containing the said type of polyurethane or its modified derivatives for preventing aggregation may further be added during the reaction. Formation of a carbon dioxide gas is observed with progress of the reaction, and termination of the formation can be determined as completion of the capsule wall-forming reaction. In general, the reaction is conducted for several hours to obtain the objective microcapsules.
  • Laser markable coating composition containing electron acceptor-type developer and the solvent free polyurethane binder
  • the exemplary coating composition is used after mixing with an electron acceptor compound which acts as the developer for the laser marking coating composition. It is preferred that the liquid coating composition be provided separately from the developer in order to maintain the stability of the coating composition.
  • the electron acceptor-type compound which reacts with the electron donor-type dye precursor, include but are not limited to an acidic substance, such as activated bentonite, metal salt of salicylate, phenol compound, organic acid or its metallic salt, and oxybenzoate.
  • an acidic substance such as activated bentonite, metal salt of salicylate, phenol compound, organic acid or its metallic salt, and oxybenzoate.
  • bisphenol compound such as 2,2-bis(4'- hydroxyphenyl)propane (generic name: bisphenol A) 1 2,2-bis(4- hydroxyphenyl)pentane, 2,2-bis(4'-hydroxy-3 ⁇ 5'-dichlorophenyl)propane 1 1 ,1- bis(4'-hydroxyphenyl)cyclohexane, 2,2-bis(4'-hydroxyphenyl) hexane, 1 ,1-bis(4'- hydroxyphenyl)propane, 1 ,1-bis(4'-hydroxyphenyl)butane, 1 ,1-bis(4'- hydroxyphenyl)pentane, 1 ,1-bis(4'-hydroxyphenyl)hexane, 1 ,1-bis (4 1 - hydroxyphenyl)heptane, 1 ,1-bis(4'-hydroxyphenyl) octane, 1 ,1-bis(4'-- hydroxyphenyl)
  • the metal salt of salicylate is preferred, for instance, zinc salicylate. Good coloring characteristics can be achieved by using this type of developer.
  • the electron acceptor-type compounds may be used singly or in a combination of two or more.
  • the electron acceptor-type compound may be used as a solid dispersion prepared in a sand mill with water-soluble polymers, organic bases, and other color formation aids or may be used as an emulsion dispersion by dissolution in a high boiling point organic solvent that is only slightly water-soluble or is water- insoluble, mixing with the waterborne and solvent-free polyurethane and its modified derivatives as the binder (aqueous phase), followed by emulsification, for example, by a homogenizer.
  • a low boiling point solvent may be used as a dissolving assistant depending on necessity.
  • the electron acceptor compound and the organic base may be separately subjected to emulsion dispersion, and also may be dissolved in a high boiling point solvent after mixing, followed by subjecting to emulsion dispersion.
  • the emulsion dispersion particle diameter is preferably about 1 ⁇ m or less.
  • the high boiling point organic solvent used can be appropriately selected, for example, from the high boiling point oils described in JP-A-2- 141279.
  • the use of an ester compound is preferred from the standpoint of emulsion stability of the emulsion dispersion, and tricresyl phosphate is particularly preferred.
  • the oils may be used as a mixture thereof and as a mixture with other oils.
  • the waterborne resins contained as the binder can be appropriately selected from the compounds: solvent-free polyurethane or its modified derivatives, such as the emulsion or suspension or dispersion of polyester based polyurethane, polyether based polyurethane, polycarbonate based polyurethane, castor oil based polyurethane, or any combinations thereof.
  • Using only the solvent-free polyurethane or its modified derivatives as the binder in a laser markable coating composition is preferred for making laser markable material.
  • a combination of polyurethane compounds and other known binder resins that are inert to color forming agents in the laser markable coating composition such as acrylic, epoxy, cellulose, and others known in the art., can be a selected as required for the marking of laser markable material.
  • the preferred concentration of the solvent-free polyurethane and its modified derivatives is about 50% or more of the total binder quantity within the liquid coating composition. This concentration is necessary in order to minimize the formation of white marks when used in combination with other binder compounds outside.
  • Mixing ratio of the oily phase to the aqueous phase is preferably from 0.02 to 0.6, and more preferably from 0.1 to 0.4.
  • the mixing ratio is in the range of from 0.02 to 0.6, a suitable viscosity can be maintained, and thus the production adequacy and stability of the coating composition become excellent.
  • compositions of electron acceptor-type developers are disclosed in US 6,797,318 Example-1 as Developer Emulsion Dispersion, US 5,409,797 Example-1 as Emulsion Dispersion, and US 5,691 ,757 Example as Color Developer.
  • Preparation of mixed coating dispersion comprising a combination of the coating composition containing a microencapsulated electron donor-type dye precursor and the coating composition containing an electron acceptor-type developer
  • the coating compositions are mixed together to prepare a mixed coating dispersion which is subsequently coated on a substrate for use as a laser markable coating layer for laser marking.
  • the mix ratio of the 2 coating compositions is such that the ratio of total weight of electron donor-type dye precursors and the total weight of the developers is between from about 1 :0.5 to about 1 :30, preferably from about 1 :1 to about 1 :1.5.
  • binder resins and auxiliary additives can be used.
  • the binder resin can be the waterborne and/or solvent-free polyurethane and its modified derivatives.
  • the auxiliary additives can be surfactants, anti-foam agents, plasticizers, rheological agents, biocides, antistatic agents, water, cross linking agents, and other compounds know in the art.
  • Auxiliary additives for better laser marking performance may also be used, such as heat transfer agents, melting agents, ultraviolet ray absorbing agents, antioxidants, and other additives known in the art.
  • a known coating method applied to an aqueous or organic solvent series coating composition is used for coating the laser markable coating composition on a support.
  • the laser markable material may further comprise, on the support, assistant layers such as a protective layer, an intermediate layer, an undercoating layer called primer, and others known in the art.
  • assistant layers such as a protective layer, an intermediate layer, an undercoating layer called primer, and others known in the art.
  • the protective layer is located on top of the laser markable material and is commonly known as a topcoat.
  • the function of the topcoat layer is to provide protection for the laser-recording layer against physical damage such as rubbing, to protect against moisture attack, to strengthen the resistance against instant heat impact, and to block attack from ultraviolet radiation, heat, and humidity.
  • Intermediate layers may also be applied on the laser markable material. They function to prevent inter-mixing of the layers and also for blocking a gas (such as oxygen) that is harmful to image preservation properties.
  • a gas such as oxygen
  • One or more undercoating layers may be applied on the support before coating the laser markable coating composition. These can include a light reflection preventing layer or other necessary functional layers necessary to improve the adhesion of the said layers to the support.
  • the binder in the coating composition of the assistant layers in a laser markable material can also be appropriately selected from a solvent-free polyurethane or its modified compounds, such as the emulsion, suspension or dispersion of polyester-based polyurethane, polyether-based polyurethane, polycarbonate-based polyurethane, castor oil-based polyurethane, or any combinations thereof.
  • a protective topcoat coating composition comprising the waterborne, solvent-free polyurethane emulsions, suspensions, and dispersions to provide necessary protection for the color forming layer in a laser markable material.
  • the protective coating composition not only provides the desired protection, but also eases the concern of the white mark problem and the stain problem that affect the quality of a laser marked material.
  • the binder components in an assistant coating composition layer.
  • the quantity of binder for the protective topcoat and other assistant layers comprises from about 10% to about 90% of the total solid weight of the protective and other assistant coating compositions. More preferably the inventive binder composition is from about 20% to about 70%, and most preferably is from about 30% to about 60% of the total solid weight of the coating composition.
  • auxiliary additives in the assistant and protective coating compositions.
  • the auxiliary additives can be regular coating additives, such as surfactants, anti-foam agents, plasticizers, rheological agents, biocides, antistatic agents, water, hardening agents, cross linking agents, and other additives know in the art.
  • Other auxiliary additives that promote the quality and performance of the laser markable materials can be also incorporated into the protective coating composition, such as heat transfer agent, ultraviolet ray absorbing agent, and others know in the art.
  • the coating composition of the protective layer preferably has a fine particle substance having a refractive index of from about 1.45 to about 1.75 from the standpoint that the transparency of the laser markable material is maintained.
  • This experiment is designed to compare exemplary solvent-free polyurethane compounds with the disclosed polyurethane compounds of WO 2006/063165 A2 in terms of performance against white mark formation.
  • a matrix exposure consisting of 70 of the same mark, the letter "M”, was applied onto each of the coated samples, using a Domino S-100 CO 2 laser marker with a f 80mm lens, which provides 35mm X 35mm marking field and a spot size of from about 250 to about 280 ⁇ m.
  • the design of the test marking matrix is such that each row consists of 7 characters, with increasing laser power output from 26.5% to 100% (5.2W ⁇ 19.6W from left to right), and 20% power increment between neighboring characters, and each column consists of 10 characters, with increasing marking speed from 1300 bits/mS to 9500 bits/mS (from bottom to top), and 20% speed increment between neighboring characters.
  • the solvent-free polyurethane and its modified derivatives are inert to the CO 2 laser energy as well as other polyurethane compounds.
  • the inertness to CO 2 laser energy is the property of polyurethane compounds in general. This property offers good performance to resist white marking caused by CO 2 laser exposure.
  • This experiment is designed to determine the stability of a laser markable material under hot and/or humid conditions and how stability is affected by incorporating the solvent-free polyurethane and its modified derivatives as a binder into a laser markable coating composition.
  • the inventive polyurethane and modified derivatives are used as a binder in making: Part A - the coating composition containing the micro-encapsulated dye precursor; and Part B - the coating composition containing the electron acceptor-type developer.
  • the inventive polyurethane and modified derivatives that are not solvent-free are used in this experiment as a reference binder to compare the experimental results. Below is the procedure to conduct the experiment.
  • the above ethyl acetate solution was added in 53 g of 6%w/w solution of the said polyurethane dispersion, and emulsified with a homogenizer at 15,000 rpm for 5 minutes.
  • Part A is completed at this step.
  • the coating composition is named A.
  • the particle size distribution of the encapsulated electron donor-type dye precursor particles and the viscosity of the liquid coating composition were measured with Beckman Coulter's LS- 100Q particle size analyzer and Brookfield Programmable DV-II+ viscometer with S21 small size spindle at 100-200 RPM.
  • the T g of the microcapsule wall is measured by using (Perkin Elmer's Diamond DSC, Sapphire DSC 1 HyperDSCTM, or TA Instruments' Q-series).
  • a blank suspension without microcapsule is prepared under the same conditions as reference sample. Both the microcapsule containing suspension and the blank suspension are placed in the sample trays before measurement.
  • Table 2-1 lists the polyurethane and its modified derivative as the replacement of polyvinyl alcohol as a binder in Part A:
  • the quantity of each binder sample is adjusted to maintain equivalent solid content.
  • Surfactant A (Trade Name: W-502, Waco Pure Chemical Industries) 11.2g
  • Surfactant B (Trade Name: NEOPELEX G-15, Kao) 11.2g Part B is completed at this step.
  • the coating composition is named B.
  • Table 2-2 lists the polyurethane and its modified derivative as the replacement of polyvinyl alcohol as a binder in Part B:
  • the quantity of each binder sample is adjusted to maintain equivalent solid content
  • Tj The coating pot solution made from Aj+Bj is named Tj
  • Each of the above mixture was coated at 15ml/m 2 on a film of A4 size and 75 ⁇ m thickness PET which was preliminarily coated with SBR lutex and gelatin, and the following laser marking was applied after drying.
  • the exemplary solvent-free polyurethane and its modified derivatives have significantly reduced stain increase compared to other polyurethane compounds that are solvent-based or that contain a solvent.
  • the laser markable material comprising the solvent-free polyurethane and its modified derivatives provide low stain after storage in a hot and/or humid environment.
  • This experiment is designed to demonstrate how the stability of a laser markable material under a hot and/or humid condition is affected by incorporating the solvent- free polyurethane and its modified derivatives as a binder into a protective topcoat layer of a laser markable material.
  • the polyurethane and its modified derivatives comprise the binder of a protective coating composition.
  • the non-inventive polyurethane and modified derivatives that are not solvent-free are used in this experiment as a reference binders for comparison to the experimental results. Below is the procedure to conduct the experiment
  • Tinuvin P Ciba Geigy Corp.
  • ethyl acetate 20 g
  • ethyl acetate 12.6 g
  • capsule wall material (Trade Name: D-140N, Mitsui Takeda Chemical Co., Ltd.) was added into the ethyl acetate solution.
  • the above ethyl acetate solution was added in 53 g of 6%w/w polyvinyl alcohol aqueous solution (Trade Name: Kurary Poval MP-103, Kuraray Co., Ltd.) and emulsified with a homogenizer at 15,000 rpm for 5 minutes.
  • polyvinyl alcohol aqueous solution (Trade Name: Kurary Poval MP-103, Kuraray Co., Ltd.)
  • Part A is completed at this step.
  • Surfactant A (Trade Name: W-502, Waco Pure Chemical Industries) 1 1.2g
  • Surfactant B (Trade Name: NEOPELEX G-15, Kao) 1 1.2g
  • Part B is completed at this step.
  • the mixing ratio is as below:
  • the above mixture was coated at a film of A4 size and 75 ⁇ m thickness PET which was preliminarily coated with SBR latex and gelatin, and the following laser marking was applied after drying.
  • Table 3-2 lists the said polyurethane and its modified derivative to be tested as a binder in the protective coating composition:
  • the quantity of each binder sample is adjusted to maintain equivalent solid content.

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  • Wood Science & Technology (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
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Abstract

L'invention concerne une composition de revêtement qui peut être marquée par un laser et qui convient pour des matériaux qui peuvent être marqués par un laser CO2. Ladite composition comprend au moins un agent de formation de couleur et au moins un polyuréthane à base d'eau sans solvant, le ou les polyuréthanes à base d'eau sans solvant étant sélectionné parmi un polyuréthane à base de polyester, un polyuréthane à base de polyéther, un polyuréthane à base de polycarbonate, et un polyuréthane à base d'huile de ricin, et le ou les polyuréthanes à base d'eau sans solvant constituant au moins 50 % en poids du poids total de liant de résine organique.
PCT/US2008/008416 2007-07-09 2008-07-09 Composition de revêtement permettant de former un matériau ayant une stabilité à la chaleur et à l'humidité et qui peut être marquée par un laser Ceased WO2009009066A1 (fr)

Applications Claiming Priority (2)

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US92968607P 2007-07-09 2007-07-09
US60/929,686 2007-07-09

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WO2009009066A1 true WO2009009066A1 (fr) 2009-01-15

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PCT/US2008/008416 Ceased WO2009009066A1 (fr) 2007-07-09 2008-07-09 Composition de revêtement permettant de former un matériau ayant une stabilité à la chaleur et à l'humidité et qui peut être marquée par un laser

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006063165A2 (fr) * 2004-12-08 2006-06-15 Fuji Hunt Photographic Chemicals, Inc. Composition servant a former un revetement pouvant etre marque au laser, et procede de formation d'un marquage par exposition a un laser

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006063165A2 (fr) * 2004-12-08 2006-06-15 Fuji Hunt Photographic Chemicals, Inc. Composition servant a former un revetement pouvant etre marque au laser, et procede de formation d'un marquage par exposition a un laser

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