Classifications

• • 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
  • C09D5/22—Luminous paints

Definitions

• the present invention relates to photoluminescent paints and other photoluminescent coatings which are safe in terms of their chemical hazard to children, pets and others handling or contacting the paint.
• Tempera paint also known as egg tempera, is a permanent fast-drying painting medium consisting of colored pigment mixed with a water- soluble binder medium (usually a glutinous material such as egg yolk or some other size). Tempera also refers to the paintings done in this medium. Tempera paintings are very long lasting, and examples from the 1st centuries AD still exist. Egg tempera was a primary method of painting until after 1500 when it was superseded by the invention of oil painting. A paint which is commonly called tempera (although it is not) consisting of pigment and glue size is commonly used and referred to by some manufacturers in America as poster paint. Paints prepared with regard to children are made with components recognized as non-toxic and safe for handling and skin contact.
• Tempera paints exhibit a variety of desirable properties including color-strength, brightness, opacity, adhesion permanence, absence of cracking, and lack of odor. Tempura paints possess excellent paint qualities while remaining safe for children to handle. However, these paints do not exhibit photoluminescence which would further enhance the appeal of paints to artist and children wanting create more exotic art work for display under low light or dark conditions.
• a photoluminescent paint including a base paint composition having a component mixture recognized as safe for human contact and exposure, and including non-toxic photoluminescent phosphor particles.
• a photoluminescent paint including a base paint composition having a component mixture recognized as safe for human contact and exposure, a viscosity modifier, and non-toxic photoluminescent phosphor particles.
• a method for decorating objects with a photoluminescent paint including a base paint composition having a component mixture recognized as safe for human contact and exposure, and including nontoxic photoluminescent phosphor particles.
• FIG. 1 is a color photograph of different child-safe photoluminescent paints of this invention under day light- type conditions
• FIG. 2 is another color photograph of the same child-safe photoluminescent paints of FIG. 1 of this invention under low light or dark conditions.
• child-safe refers to components that are recognized as safe for human contact and exposure by organizations such as the Art & Creative Materials Institute, Inc. (ACMI), including safe to children as well as other age groups, but which are not necessarily safe for human ingestion in bulk quantities.
• ACMI Art & Creative Materials Institute, Inc.
• This invention recognizes that child-safe phosphors (i.e., phosphors that have received ACMI “approval” or “pre-approval”) can be mixed with child-safe paints to produce a unique paint product having both color and luminescent properties such that an object painted will exhibit permit desirable properties including for example color-strength, brightness, and opacity under normal lighting conditions and will be visible in low light or dark conditions.
• a viscosity modifier may be added to minimize settling and clumping of the phosphor particles.
• Figure 1 is a color photograph of different color child-safe photoluminescent paints of this invention under normal or daylight-type conditions.
• the far left paint sample represents that of a conventional child-safe "white" paint without any phosphor additions.
• the remaining paint samples shown in Figure 1 have different phosphors and color pigments added. A more complete discussion of the phosphor additions and color palette realized will be given below.
• Figure 2 is a color photograph of the same child-safe photoluminescent paints of Figure 1 but under low light or dark conditions. From left to right, the photoluminescrent colors realized in these examples are: natural, yellow, yellow-orange, rose, blue, orange, and green. Other colors are possible especially with the addition of different color pigments or dyes. As seen in Figure 2, the child-safe photoluminescent paints of this invention offer to the painter a rich variety of colors whose illumination in the dark adds a dimension to the art work, capturing the observer's attention.
• Luminescence is a long known phenomenon of nature. Recorded observations reach back to the last century. During that time period, words like "phosphor” and “luminescence” appeared in the art. In 1904, Dahms distinquished between “stimulation” and “quenching,” meaning inducing or stopping afterglow. Much of the later work is associated with Lenard, who received the Nobel Prize in 1905 in physics for cathode ray emission. Lenard studied different phosphors until at least 1918. Later work can be found by Urback in 1926 through 1934. These early scientists basically observed very small luminescent effects. In 1941, a program was instituted by the National Defense Committee for development of light emitting phosphors.
• photoluminescent phosphors are inorganic solids prepared from a metal cation, a nonmetal anion and an activator.
• the activator is usually a transition or a rare earth element which when added in small amounts (0.1% to 5%) can alter the color of the emitted light.
• ZnS zinc sulfide
• Cu element cadmium
• ZnS:Ag additive of the element cadmium (Cd) to ZnS:Ag increases the wavelength to green and extends the lifetime to 200 microseconds.
• the inorganic phosphor ZnCdS 2 :Ag can actually be tuned in color by varying the Cd level from blue (no Cd) to red (high Cd).
• Zinc sulfide with about 5 ppm of a copper activator is the most common phosphor for the glow-in-the-dark novelty items. It is also called a GS phosphor.
• a mix of zinc sulfide and cadmium sulfide emit color depending on their ratio; increasing of the CdS content shifts the output color towards longer wavelengths; its persistence ranges between 1-10 hours.
• the photoluminescent phosphors, or pigment used in one embodiment of this invention are mixed with child-safe paint to produce a child-safe photoluminescent paint.
• One suitable child-safe phosphor of the invention is a high-temperature processed crystalline zinc sulfide.
• Zinc-sulfide based pigments can glow with many colors.
• phosphorescent phosphors sulfide phosphorescent phosphors are known. Examples of sulfide phosphorescent phosphors include CaS:Bi (which emits light of violet blue), CaStS:Bi (which emits light of blue), ZnS:Cu (which emits light of green) and ZnCdS:Cu (which emits light of yellow or orange).
• Zinc sulfide pigments are capable of absorbing ambient UV-light, daylight or artificial light, store the light energy and discharge it over an extended period of time. (Additionally, these pigments are not radioactive and are nontoxic.) Luminescence of sulfides, selenides and tellurides of Zn, Sr, Cd, Hg, and others, is due to the presence of luminescent centers in the host crystal. For instance, Cu + centers in ZnS give rise to luminescence at 520 nm. Mn 2 is also a luminescent center for ZnS. The emission maximum in this case is situated at about 590 nm.
• strontium aluminate More strontium aluminate activated by europium, SrAl 2 0 4 :Eu(II):Dy(III), is a suitable material with a higher brightness and significantly longer glow persistence than the undoped strontium aluminate.
• SrAl 2 0 4 :Eu(II):Dy(III) produces green and aqua hues, where green gives the highest brightness and aqua the longest glow time.
• SrAl 2 0 4 :Eu:Dy is about 10 times brighter, 10 times longer glowing, but 10 times more expensive than ZnS:Cu.
• the excitation wavelengths for strontium aluminate range from 200 to 450 nm.
• the wavelength for its green formulation is 520 nm, its blue-green version emits at 505 nm, and the blue one emits at 490 nm. Colors with longer wavelengths can be obtained from the strontium aluminate as well, though for the price of some loss of brightness.
• these child- safe phosphors are mixed with child-safe paints such as those discussed below.
• U.S. Pat. No. 4,826,535 (the entire contents of which are incorporated herein by reference) describes a tempera paint composition which is easily removed by washing from the fibers of clothing garments is provided. A number of other U.S. patents also describe tempera paint compositions which are suitable for the invention.
• U.S. Pat. No. 7,153,356 (the entire contents of which are incorporated herein by reference) describes a washable paint composition which can be created in a variety of vivid colors, has good aesthetics— the paint does not drip, and paints smoothly.
• the polyethylene glycol, the water swellable clay, and high molecular weight cellulosic thickener improve fabric and skin washability.
• a number of other U.S. patents also describe washable paint compositions which are suitable for the invention if recognized as child-safe. Commercially available child-safe paints are also suitable.
• One example is a product sold by Rich Art Inc. under the tradename CLEAN COLORS WASHABLE PAINT.
• U.S. Pat. No. 5,320,670 (the entire contents of which are incorporated herein by reference) describes a vegetable oil, in particular a soy oil, based paint composition which is bioreducible and non-toxic.
• the child safe products of the invention would preferably not contain volatile organic compounds or VOCs (i.e., organic chemical compounds that have high enough vapor pressures under normal conditions to significantly vaporize and enter the atmosphere.)
• VOCs volatile organic compounds
• Particular VOCs used in many commercial paints which would be avoided or minimized in child safe products to concentrations of less than 1.0 mg/m 3 and preferably less than 0.3 mg/m 3 would include aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated solvents, dichlorobenzene, n-butyl acetate, 4-phenylcyclohexene, terpenes, ethyl acetate, glycol ethers, or acetone or combinations thereof.
• Child safe products do not contain heavy metals such as Pb, Cd, and Te at concentration of more than 0.06% or preferably less than 0.009%.
• Children's products today have to have a lead concentration of less than 0.06% or preferably less than 0.009% for younger children. Detailed restrictions on lead are found in requirements published in 16 C.F.R. 1303.
• a composition is formed from an "exotic" pigment, chosen for exhibiting a particular color.
• Suitable exotic pigments include D&C Yellow No. 5 (Pigment Yellow 100), Clarion Red (Pigment Orange 46), Barium Lithol (Pigment Red 49:1), D&C Blue No. 1 (Aluminum Lake), D&C Red No. 27 (Aluminum Lake) (Solvent Red 48), Victoria Blue Lake (Pigment Blue 1), Prussian Blue (Pigment Blue 27) and Lithol Rubine (Pigment Red 57).
• pigments tempera base that also can be used include D & C Yellow No. 6 (Aluminum Lake, Pigment Yellow 104), FD & C Blue No. 2 (Aluminum Lake, Pigment Blue 63), Acid Violet 4 BNS (Acid Violet 17), and Calcium Lithol (Pigment Red 49:2) and Titanium Dioxide (white).
• the pigment chosen can be present in an amount between about 0.8 and 2.0 weight percent.
• a carbon dioxide liberating substance can be included which produces carbon dioxide during laundering to assist in lifting the paint from the clothing fibers.
• the carbon dioxide liberating substance usually has a pH between 5.5 and 8.5.
• Examples of carbon dioxide liberating substances include an alkaline metal bicarbonate, such as sodium bicarbonate, potassium bicarbonate and strontium bicarbonate.
• Another carbon dioxide liberating substance is ammonium carbonate.
• the carbon dioxide liberating substance can be present in the paint composition in an amount between about 0.5 and 2.0 weight percent.
• a pH buffer or water softener can be present for example in an amount between 0.5 and 0.25 weight percent.
• One preferred pH buffer is sodium pyrophosphate.
• Other suitable pH buffers include disodium hydrogen phosphate, sodium hexametaphosphate and disodium dihydrogen pyrophosphate.
• a pigment extender or filler can be present for example in an amount between about 10 and 30 weight percent.
• the pigment extender functions to prevent the paint surface from being sticky.
• One suitable pigment extender is diatomaceous silica, which has a skeletal structure capable of holding pigment particles in its interstices and is present in an amount between about 10 and 15 weight percent.
• Other pigment extenders may be added to the diatomaceous silica in an amount between about 10 and 18 weight percent.
• Other suitable pigment extenders include silica clays, such as china clay, and non-clay extenders such as barium sulfate and calcium carbonate.
• a binder or adhesive which enables the paint composition to stick to a surface during application, can also be present.
• One exemplary adhesive is a starch solution.
• the adhesive can be present for example in concentrations between about 5 and 50 weight percent.
• Other suitable binders or adhesives include natural gums.
• the composition can include a plasticizer, which helps to make the paint soft and porous.
• a plasticizer is a glucose plasticizer in combination with a glycerine plasticizer which, although more costly than the glucose plasticizer, is included to confer controlled absorption of moisture from the air.
• Other suitable plasticizers include invert sugar and fructose syrup.
• the plasticizer component can be present in an amount between about 5 and 15 weight percent, an amount which exceeds that normally included in conventional water based paints.
• the excess plasticizer insures that the paint surface remains soft, even several days after application, which is desirable so that the paint can be more easily washed from the user's clothes.
• a preservative can also be included in the composition.
• the preservative in one embodiment is present in an amount between about 0.1 and 0.25 weight percent.
• the preservative can chosen from glutaraldehyde, benzoic acid, para -chloro-meta-xylenol and other phenolic derivatives.
• An opacifier is also an optional ingredient which might be added to the composition.
• the opacifier functions to make the paint film opaque, rather than transparent.
• the preferred opacifier is titanium dioxide and the opacifier, if present, is present in an amount up to about 15 weight percent. Suitable substitutes for titanium dioxide as the opacifier include lithopone, barium sulfate and zinc oxide.
• the composition may also include a paint thickener, which is preferably present in an amount between about 0.6 and 3.5 weight percent.
• the preferred paint thickener is a combination of attapulgite clay and xanthan gum.
• the attapulgite clay is an insoluble thickener, and can be present in an amount between about 0.5 and 3.0 weight percent.
• the xanthan gum is a water soluble thickener and could be present in an amount between about 0.1 and 0.5 weight percent. Although either thickener may be used alone, it is preferred to use both.
• non-soluble thickeners instead of the attapulgite clay, other suitable non-soluble thickeners would include bentonite and montmorillonite. Instead of xanthan gum, other suitable water soluble thickeners include alkali metal alginates and carboxy methyl cellulose.
• a composition is formed to have about 2.5 to 10 weight percent of a high molecular weight polyethylene glycol having a molecular weight between 2,000 and 20,000, a water swellable clay in the amount of 0.5 to 1.5 weight percent; and a high molecular weight cellulosic thickener in the amount of about 1.0 to 2.5 weight, percent, wherein the high molecular weight cellulosic thickener has a viscosity between 500 and 15,000 cps tested as a 2% by weight solution in water at 25° C.
• a high molecular weight polyethylene glycol can improves both fabric and skin wash results, when added to the paint in an amount of about 2.5 to 10 weight percent.
• the high molecular weight PEG has a molecular weight of between 2,000 and 20,000, more preferably between 3,000 and 10,000.
• Lower molecular weight PEG's have a positive effect on removal from fabric and skin but the effect is not as great as high molecular weight.
• High percentages (above approximately 12%) of PEG adversely affect the paint stability with noticeable separation of the paint components occurring in just a few days. At lower percentages (about 2.5 to 10% wt), the paint is stable at 40° C.
• the cellulosic thickener deters the colorants from diffusing into the paper with the water.
• Preferred cellulosic thickeners include, but are not limited to carboxymethyl cellulose (CMC), methylcellulose, and other cellulosic compounds.
• CMC has been found to keep colorants on the surface of the paper and paints with CMC have stability at higher temperature.
• the high molecular weight CMC will diffuse much slower into the paper than water.
• the CMC and other preferred cellulosic thickeners have a molecular weight of between 100,000 to 1,500,000.
• the viscosity of a 2% by weight solution of the cellulosic thickener is between 500 and 15,000 cps tested as a 2% by weight solution in water at 25° C, using a Brookfield DV-II+ viscometer with a number 21 spindle, a small sample adaptor for Brookfield and a speed of 2 rpm.
• the high molecular weight cellulosic thickener is found in an amount between 0.25 to 2.5 percent by weight, more preferably 0.5 to 1.5 percent by weight of the formulation. With many other thickeners, the polymeric colorants can migrate into the paper with the water giving lighter appearing color on paper.
• Formulations of this base paint for use here in the child-safe photoluminescent paints can utilize smectite and other water swellable clays in coatings to develop specific rheological and performance properties in formulations.
• Water swellable clays contain plates or platelets and are capable of hydrogen bonding. These properties are a result of their unique particle morphology, swelling capability and stable gel structure. This structure provides a shear thinning profile leading to many key characteristics. These characteristics include thixotropic flow, excellent spray properties, superior suspension and resistance to sag that can differentiate coatings in the market.
• swellable clay is a smectite clay.
• Smectite is a family of layered silicate clays that have the ability to swell in water. Within this family are the inorganic clays of the montmorillonite type (eg bentonite or aluminium silicate) and hectorite (magnesium silicate). The effect as thickener is based on a spatial alignment of the clay platelets or gel formation by hydrogen bonding.
• the water swellable clay is found in amount of between 0.25 and 1.5% by weight, more preferably 0.5 to 1.0% by weight in the paint formulation.
• "Dry" Water Based Paint Composition is a family of layered silicate clays that have the ability to swell in water. Within this family are the inorganic clays of the montmorillonite type (eg bentonite or aluminium silicate) and hectorite (magnesium silicate). The effect as thickener is based on a spatial alignment of the clay platelets or gel
• a base paint composition suitable for this invention (based on the washable paint of U.S. Pat. No. 6,235,273), a composition is formed using two different weight polyethylene glycol waxes together with stearic acid, calcium carbonate, talc, titanium dioxide, guar gum, a preservative and a colorant.
• the '273 describes the material of the paint being formed by initially mixing dry granular form ingredients at room temperature. Once mixed, the material was subjected to a melt at approximately one hundred fifty degrees centigrade to form a paste which is poured within a mold to cool forming a dry cake.
• the phosphors would be added in with the dry granular ingredients and mixed/
• the composition is formed by combining a pair of waxes such as polyethylene glycol-32 and polyethylene glycol- 180 together with stearic acid and calcium carbonate. A quantity of talc together with titanium dioxide and guar gum is also added. A preservative and colorant is further added.
• the basic ingredients include carbowax 1450, carbowax 8000, stearic acid, calcium carbonate, talc, titanium dioxide, jaguar 8012 and phenonip. Carbowax 1450 and Carbowax 8000 are both polyethylene glycol waxes. Stearic acid, calcium carbonate, talc and titanium dioxide are generic compound names. Jaguar 8012 is a commercial name of a guar gum and phenonip is a well known preservative.
• a child user can employ a conventional applicator having the capability to absorb and retain a quantity of water.
• the water mixing and applicator is very similar to the process employed with water color paints.
• Soy or Vegetable Oil-Based Paint Compositions As one example of a base paint composition suitable for this invention (based on the paint of U.S. Pat. No. 5,320,670), a composition comprised predominantly of vegetable oil, more particularly soybean oil, is advantageous because (i) it dries within a period of at least one hour but less than 5 months, preferably 10 days, (ii) it possess the quality, richness, and pliability of conventional oil base paints and (iii) it reduces, if not eliminates, the odor and irritation associated with harsh chemicals, in particular, turpentine, alcohol, mineral spirits, and other volatile organic compounds.
• This composition includes a primary oil, more particularly soybean oil, antioxidants, dryers and a secondary oil.
• a colorant (including the phosphors noted above) as well as a viscosity modifier can be to produce for example a mixture of primary oil, dryers and pigments in the ratios of about 60%-95%: l%-5%:5%-20%, more particularly, a ratio of 65%- 75%: 1.5%-2.5%: 10%-20% .
• the primary oil of this composition (which serves as the predominant ingredient of the paint of the instant invention) is a vegetable oil, usually from the class of "edible" oils, most particularly soybean oil.
• the proportion of primary oil is greater than 50% by weight, usually between about 60% to about 95%, more particularly about 65% to about 75%.
• Suitable dryers for this composition are those which do not contain harsh turpentine and other volatile organic solvents.
• dryers are selected from the group of oxides of manganese, cobalt, zirconium, carboxylate, calcium and mineral spirits.
• a selected dryer may be used alone or in combination with other dryers.
• the proportion of dryers can range between about 1% and about 5%., more particularly, about 1.5%) to about 2.5%, even more particularly 1.5% to about 1.7%.
• a secondary oil of this composition can include boiled linseed oil added in a range between about between about 3% and about 15%, more particularly, between about 4% and about 10%).
• boiled linseed oil added in a range between about between about 3% and about 15%, more particularly, between about 4% and about 10%.
• Another component of this composition is an antioxidant in the proportion of about
• antioxidants in particular those used as anti-rancidity agent in foods and in vitamins, can be used.
• Antioxidants such as butyl-P-cresol and butylated hydroxytoluene (BHT) are particularly suited for use.
• Colorants of this composition include pigments, dyes or other color imparting agents.
• organic and inorganic pigments which are far less toxic than "heavy metal toxic levels" are selected.
• pigments such as Napthol Red, Aylide Yellow, Carbazole Violet, Phthlocyanine Blue, Quinacridone, Azo Yellow, Napthol Red Light, Ultramarine, Burnt Umber, Burnt Sienna, Raw Umber and Raw Sienna or combinations thereof are suitable.
• These pigments tend to be in a dry powder form and are available through channels known to those skilled in the art. Generally, the proportion of pigment ranges from about 5% to about 20%.
• Fillers such as silica or others well known in the art may be added in quantities sufficient to give the composition a preferred "body.” In various embodiments, a proportion of between about 4% and about 10%, more particularly about 6.9% to about 7.5%, is used. However, as the array of suitable pigments is vast and the properties of the pigments vary, percentages of filler outside these ranges are foreseeable as the amount of filler depends upon the properties of the pigments.
• zinc sulfide ZnS and strontium aluminate SrAl 2 0 4 are suitable additives to child-safe paint formulations.
• these phosphors can be added for example at a weight concentration of 2 to 60%. In other embodiments, the above noted phosphors are added at weight concentration of 10 to 30%. In other embodiments, the above noted phosphors are added at weight concentration of 15 to 25%.
• the Zinc Sulfide colored phosphors used in one embodiment are United Minerals Corporation (UMC): GSS 6SSU Natural, GSS 205/1 -Yellow, GSS 207/1 -Orange- Yellow, GSS 8B/1-Blue, GSS 507/1 -Rose, GSS 305/1 Orange, and GSS 905/1 -Green.
• UMC United Minerals Corporation
• MT series pigment colors green, blue, yellow, orange-red, orange
• Lanxi Minhui Photoluminescent Co., Ltd., Zhejiang, China are used.
• a viscosity modifier, or leveling agent such as KY-366 from Changzhou Keyuan Chemical Co., Ltd., Jiangsu, China or Flood Floetrol from AkzoNobel Decorative Paints, USA, Strongsville, OH, or other similar products suitable for use in a tempera paint is used to adjust the paints viscosity and prevent settling and clumping of the photoluminescent phosphors.
• the viscosity of the photoluminescent paint is between 80 to 100 Pascal seconds. In one embodiment of the invention, the viscosity of the photoluminescent paint is between 50 to 80 Pascal seconds. In one embodiment of the invention, the viscosity of the photoluminescent paint is between 100 to 150 Pascal seconds.
• the above-noted child-safe photoluminescent paints can be applied using standard painting utensils (brushes, spray guns, etc.) to a variety of surfaces including, but not limited to, paper, plastics, ceramics, glass, cloth, fabric, wood, metal, leather, etc.
• the paints once applied can cure at room temperature conditions or may be heated to advance the drying by way of ovens or heated convective air supplies or radiators.

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Citations (9)

• 2013
  • 2013-01-31 WO PCT/US2013/024068 patent/WO2013116471A1/fr not_active Ceased

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