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Title:
INFRARED ABSORBER
Document Type and Number:
WIPO Patent Application WO/2008/127409
Kind Code:
A2
Abstract:
An antimony tin oxide (ATO) nanoparticle useful for infrared energy transfer, composites, methods of use, and methods of making thereof. The antimony tin oxide nanoparticles have a mean particle size less than or equal to 100 nm and an antimony content greater than or equal to 5.0 atomic percent of the antimony tin oxide nanoparticles themselves, wherein the antimony tin oxide nanoparticles have a particle size distribution, as measured by the ration or D90/50, less than or equal to 2.0, and wherein the antimony tin oxide nanoparticles have, when dispersed at 500 ppm in ethylene glycol, a figure of merit greater than or equal to 0.50.

Inventors:
GAUDET GREGORY T (US)
ZVOSEC RICHARD T (US)
STILL MARK (US)
RUSSELL VALERIE (US)
Application Number:
PCT/US2007/083779
Publication Date:
October 23, 2008
Filing Date:
November 06, 2007
Export Citation:
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Assignee:
NANOPRODUCTS CORP (US)
GAUDET GREGORY T (US)
ZVOSEC RICHARD T (US)
STILL MARK (US)
RUSSELL VALERIE (US)
International Classes:
C01G19/02; C01G30/00; B29C49/00
Domestic Patent References:
WO2005095516A12005-10-13
WO2005047009A12005-05-26
Foreign References:
US20060269739A12006-11-30
US20050163999A12005-07-28
Other References:
NANOPHASE TECHNOLOGIES: "NanoTek® Antimony Tin Oxide" 2008, , XP002507234 Retrieved from the Internet: URL:http://www.nanophase.com/catalog/item.asp?ITEM_ID=32&DEPARTMENT_ID=32> [retrieved on 2008-12-08] the whole document
Attorney, Agent or Firm:
PALLADINO, Donald, R. (PPG Industries Inc.,One PPG Plac, Pittsburgh PA, US)
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Claims:
WHAT IS CLAIMED IS:

1. Antimony tin oxide nanoparticles having a mean particle size less than or equal to 100 nm and an antimony content greater than or equal to 5.0 atomic percent of the antimony tin oxide nanoparticles themselves.

2. The antimony tin oxide nanoparticles of claim 1 , wherein the antimony content is greater than or equal to 15.0 atomic percent of the antimony tin oxide nanoparticles themselves.

3. The antimony tin oxide nanoparticles of claims 1-2, wherein the antimony content is greater than or equal to 20.0 atomic percent of the antimony tin oxide nanoparticles themselves.

4. The antimony tin oxide nanoparticles of claim 1 , wherein the antimony content ranging from 5.0 to 20.0 atomic percent of the antimony tin oxide nanoparticles themselves.

5. The antimony tin oxide nanoparticles of claims 1-4, wherein the antimony tin oxide nanoparticles, which, when dispersed at 500 ppm in ethylene glycol, have a figure of merit greater than or equal to 0.50.

6. The antimony tin oxide nanoparticles of claim 5, wherein the figure of merit is greater than or equal to 1.0.

7. The antimony tin oxide nanoparticles of claim 5, wherein the figure of merit is greater than or equal to 1.25.

8. The antimony tin oxide nanoparticles of claim 5, wherein the figure of merit is greater than or equal to 2.0.

9. The antimony tin oxide nanoparticles of claim 5, wherein the figure of merit is greater than or equal to 10.0.

10. The antimony tin oxide nanoparticles of claim 5, wherein the figure of merit ranges from 2.0 to 5.0.

11. The antimony tin oxide nanoparticles of claims 1-10, wherein the antimony tin oxide nanoparticles have a particle size distribution, as measured by the ratio of D90/D50, less than or equal to 2.0.

12. The antimony tin oxide nanoparticles of claim 11 , wherein the particle size distribution is less than or equal to 1.5.

13. The antimony tin oxide nanoparticles of claim 11 , wherein the particle size distribution ranges from 1.5 to 3.0.

14. The antimony tin oxide nanoparticles of claims 1-13, wherein the mean particle size equals less than 50 nm.

15. The antimony tin oxide nanoparticles of claims 1-13, wherein the mean particle size equals less than 20 nm.

16. The antimony tin oxide nanoparticles of claims 1-13, wherein the mean particle size ranges from 5 to 30 nm.

17. Use of the antimony tin oxide nanoparticles of claims 1-16 for heating a polymeric article.

18. The antimony tin oxide nanoparticles of claims 1-16, wherein the antimony tin oxide nanoparticles are in a medium suitable for energy transfer.

19. Use of the antimony tin oxide nanoparticles of claims 1 - 16 for making a polymeric article comprising, in a medium suitable for energy transfer, the antimony tin oxide nanoparticles of claims 1-16.

20. Antimony tin oxide nanoparticles having a mean particle size less than or equal to 100 nm and an antimony content greater than or equal to 5.0 atomic percent of the antimony tin oxide nanoparticles themselves, wherein the antimony tin oxide nanoparticles have a particle size distribution, as measured by the ratio of D90/D50, less than or equal to 2.0, and wherein the antimony tin oxide nanoparticles, which, when dispersed at 500 ppm in ethylene glycol, have a figure of merit greater than or equal to 0.50.

Description:

INFRARED ABSORBER

[0001] This application claims priority to US provisional application no. 60/857,115 filed November 7, 2006 and US provisional application no. 60/907,050 filed March 19, 2007, the disclosures of which are incorporated herein by reference in their entireties.

[0002] In some embodiments, this invention relates to an antimony tin oxide (ATO) nanoparticle useful for infrared energy transfer. More specifically, in some embodiments, this invention relates to an ATO nanoparticle having a combination of particle size and particle composition that make it possible to achieve both high absorption of near infrared light and low absorption of visible light. In some embodiments, this invention relates to an ATO nanoparticle having a ratio of infrared absorbance to visible absorbance. In some embodiments, this invention also relates to composite materials, including, for example, polymers, inks and coatings, containing the ATO nanoparticle. In some embodiments, this invention also relates to using the ATO nanoparticle for energy transfer to a composite material, including infrared heating, curing or drying. In some embodiments, the present invention relates to an infrared absorber containing the ATO nanoparticle, and in some embodiments, the infrared absorber is capable of transferring energy to a medium suitable for supporting the infrared absorber, and in some embodiments, the medium is a polymer as well as uses and methods of making infra red absorber, compositions, and articles thereof. [0003] Many plastic packages, especially poly(ethylene terephthalate) (PET) and oriented polypropylene (OPP) beverage bottles, are formed by a process called Reheat Blow Molding (RHB). In RHB, a preform or parison is heated to a certain temperature and then blown to fill a mold. The time required for the parison to reach the certain temperature is known as the reheat time or reheat rate of the material and varies as a function of the absorption characteristics of the polymer itself as well as any additives such as metals, catalysts, toners, dyes, or included foreign matter. With time, it has become possible to produce more bottles per hour, but it is still desirable to provide polymers which reheat faster or with less energy.

[0004] The heat lamps used in the beverage bottle industry typically are quartz lamps having a broad emission spectrum ranging from 500 nm to greater than 1500 nm. The quartz lamps' emission maximum is around 1100-1200 nm typically. Polymers like polyesters, and especially PET, and more especially OPP, absorb poorly in the region between 500 and 1400 nm. Additionally, the parison is suspended in air and not in contact with a surface that can absorb the infrared and transfer heat to the parison. Thus to improve the reheat rate of these polymers, one could increase the absorption of radiation by the polymer by addition of an additive known to absorb in the region of emission of the heat lamps, preferably in the region of maximum emission.

[0005] In the printing and coatings industries, similar infrared lamps are often used to improve the rate of drying or curing of inks, overprint varnishes, industrial coatings, and paper coatings. Lamps with varying emission spectra are often deployed against materials with poor absorption characteristics. Often, the industry relies on heating the substrate on which the coatings, adhesives, varnishes, papers, and inks has been applied and allowing heat to transfer from the substrate to the coatings, adhesives, varnishes, papers, and inks, which is inherently inefficient with respect to heat. To improve this process, one could increase the direct absorption of radiation by adding an infrared absorber to the ink, varnish, or coating. If the absorber operates effectively in the region of maximum emission of the heat lamps, it will generate more heat directly in the material to be dried/cured, utilizing the radiant energy more efficiently. This will permit faster operation of the application machinery and increase productivity.

[0006] In the construction and automotive industries, films such as PET and glass laminating adhesives such as poly (vinyl butyral) (PVB) are often treated with reflectors and/or absorbers to control the specific types of light that will pass through a window. This serves to reduce glare, deterioration of upholstery and carpeting, and heat entering a room or vehicle, among other things. As the amount of energy contained in sunlight is greater than 50% from the infrared region, addition of an effective infrared absorber to the PVB or PET can be very effective in controlling energy transfer through a window.

[0007] Various forms of antimony tin oxide are all well-known IR absorbing materials. Moreover, various forms of nanoparticles of these materials have been used to make visibly transparent nanocomposite polymers and coatings with IR absorbing properties. Generally, antimony tin oxide (ATO) is one of the less expensive of these materials, but unfortunately ATO is also one of the poorer performing materials in IR absorbing applications.

[0008] Antimony tin oxide is one of the transparent conductive oxides that has been used in thin film coatings. For example, Shanthi et. al. examined the optical and electrical properties of antimony tin oxide thin films, and they concluded that the optimum antimony content is 9%. (Crystal Res. Technol. Vol. 34, No. 8, pg. 1037- 1046 [1999]).

[0009] Antimony tin oxide has also been used in nanoparticle form as an additive for polymers, inks, and coatings.

[0010] U.S. Patent No. 7, 187,396 B2, assigned to Englehard Corporation, discloses a low visibility laser marking additive based on antimony tin oxide (Claim 2). The additive is intended to be used with an Nd:YAG laser that emits in the infrared at 1064 nm (Col. 3, Line 37). Preferred ranges for antimony content are up to 17% (Col. 4, Line 25), but most preferably about 2% (Col. 4, Line 30). Preferred ranges for particle size are between 10 and 70 nm, and more preferably between 20 and 50 nm (Col. 4, Line 29).

[0011] U.S. Patent Application Publication No. 2006-0269739, assigned to E I du Pont de Nemours and Company, discloses nanoparticulate solar control composites, which can be include nanoparticulate antimony tin oxide (Claim 1). The preferred antimony content is 0.1 to 20 weight percent, more preferred 5 to 15 weight percent, still more preferred 8 to 10 weight percent (Paragraph 31). The preferred particle size is less than 100 nm, with more preferred size less than 50 nm, still more preferred less than 30 nm, and still more preferred between about 1 nm and 20 nm (Paragraph 29). [0012] International Patent Application PCT/GB05/0012331, assigned to Colormatrix Europe Limited, discloses polymer additives for infrared reheating of polyester, including antimony tin oxide (Claim 9). The antimony tin oxide had an average particle size of 30 nm (Page 17, Item 3); the antimony content is not

disclosed. In Table 2, the application shows that the antimony tin oxide additive has a %Reheat/Unit of Lightness Lost of 1.18 (Example 8), compared to control values of 0.8 and 0.92 (Laser+ and CBl Ie). For comparison, a nanoparticulate tin-doped indium oxide has a much higher value of 6.67 (Example 6). So, the application shows that the antimony tin oxide is not optimized for the balance of infrared absorption and visible transparency, compared to the tin-doped indium oxide. [0013] International Patent Application PCT/EP2003/007796, assigned to Merck Patent GMBH, discloses particulate semiconductor materials as a hardening or drying additive or for improving the thermal conductivity of lacquer systems and printing inks. The particulate materials include mixtures of antimony oxide and tin oxide (Claim 5). The particle sizes are between 10 nm and 2000 microns, preferably between 100 nm and 100 microns, more preferably between 500 nm and 30 microns. The preferred dopant level is not disclosed specifically for antimony tin oxide, but for the semiconductor materials in general, the suitable level is disclosed as 0.01 to 30%, especially 5-16%.

[0014] In summary, the prior art for antimony tin oxide nanoparticles does not disclose a combination of particle size and particle composition that gives improved infrared absorbance. The most preferred antimony composition in the prior art is generally between 5% and 16%, more specifically between 8% and 10%. The prior art does not disclose an antimony tin oxide nanoparticle with a preferred particle size and particle composition to give a high ratio of infrared absorption to visible absorption. This prior art is confirmed by commercially available antimony tin oxide nanoparticles (reference NanoPhase, American Elements, Inframat webpages, last checked March 2007), which have antimony content of 8%-10%, and particle size of between 10 nm and 30 nm.

[0015] It is accordingly, in some embodiments, a primary object of the invention to develop an ATO nanoparticle that makes it possible to achieve improved IR absorbing properties, suitable for transparent nanocomposites. This is achieved, in some embodiments, by making ATO having a particular combination of particle size distribution and particle composition.

[0016] Furthermore, efforts to increase the IR absorption of coatings, inks, and adhesives are met with a number of problems, because the addition of IR absorbing material can adversely affect the performance and characteristics of the coatings, inks, or adhesives. For example, the IR absorbing material may alter the color or transparency of a coating, which is particularly problematic in applications such as clearcoats and color finishes. The coatings, inks, or adhesives also may not absorb IR radiation uniformly depending on the distribution of the IR absorbing material in the coatings, inks, or adhesives. The IR absorbing material may also adversely affect the performance of the coatings, such as be decreasing adhesivity of adhesives or making coatings less durable.

[0017] Thus, there exists a need for coatings, inks, and adhesives that dry or cure efficiently while retaining good performance and physical characteristics. There is also a need for IR absorbing materials that can be used with coatings, inks, and adhesives to dry or cure the materials more efficiently. Methods of effectively and efficiently drying and curing coatings, adhesives, and inks are also needed. To make it possible to address these and other needs, the present invention provides infrared (IR) absorbing nanoparticles that are substantially transparent to light in the visible spectrum. The present invention also makes it possible to provide coatings, inks, and adhesives comprising these IR absorbing nanoparticles, and methods of drying and curing coatings, inks, and adhesives using IR energy.

[0018] Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

[0019] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one (several) embodiment(s) of the invention and together with the description, serve to explain the principles of the invention.

[0021] Reference will now be made in detail to multiple embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a graph showing the absorbance of ethylene glycol comprising different IR absorbing materials as a function of wavelength. The graph demonstrates that nanoparticles of reduced indium tin oxide (rITO) and antimony tin oxide (New

Material) absorb IR radiation and are substantially transparent to light in the visible spectrum. Carbon black, on the other hand, absorbs energy in both the IR and visible spectrums.

[0023] Unless otherwise specified, "a" and "an" mean "one or more than one."

[0024] Unless otherwise specified, the term "or" is inclusive unless otherwise explicitly stated that the term is exclusive.

[0025] As used herein, "nanoparticles," "nanoscale powders," "nanocrystals," and

"nanosize powders" are used interchangeably. Nanoparticles means particles with a mean diameter of less than 10 microns and an aspect ratio ranging from 1 to

1,000,000. In some embodiments, the nanoparticles have a mean diameter of less than or equal to 250 nm. More embodiments are described below. In some embodiments, the nanoparticles have an aspect ratio ranging from 1 to 100. For example, a nanoparticle can have a mean diameter of 250 nm and an aspect ratio of

50.

[0026] In some embodiments, the invention is antimony tin oxide (ATO) nanoparticles having a mean particle size less than or equal to 250 nm and an antimony content greater than or equal to 5.0 atomic percent of the antimony tin oxide nanoparticles themselves.

[0027] In any embodiment, the atomic percent of the antimony in the ATO nanoparticles may vary as explained here. For example, in some embodiments, the antimony content is greater than or equal to 10.0 atomic percent of the antimony tin oxide nanoparticles themselves. In other embodiments, the antimony content is

greater than or equal to 12.5 atomic percent of the antimony tin oxide nanoparticles themselves. In some other embodiments, the antimony content is greater than or equal to 15.0 atomic percent of the antimony tin oxide nanoparticles themselves. In some other embodiments, the antimony content is greater than or equal to 17.5 atomic percent of the antimony tin oxide nanoparticles themselves. In some other embodiments, the antimony content is greater than or equal to 20.0 atomic percent of the antimony tin oxide nanoparticles themselves.

[0028] Furthermore, in some embodiments, the antimony content ranges from 5.0 to

20.0 atomic percent of the antimony tin oxide nanoparticles themselves, and in other embodiments, the antimony content ranges from 10.0 to 25.0 or 15.0 to 20.0 atomic percent of the ATO.

[0029] In any embodiment, the figure of merit of the ATO nanoparticles may vary as explained here.

[0030] A figure of merit (FOM) is be defined by the extinction of the composite material at 1100 nm (επoonm) divided by the extinction at 550 nm (εssonm):

FOM = εnoonm/εssonm (1)

[0031] In formula (1), ε is approximated by Beer's Law (A=εCl), in which A is the absorbance or Optical Density (OD), C is the concentration, and 1 is the path length.

In practice, the FOM may be determined by a ratio of ODs:

FOM = OD 110 o nm /OD 550nm (2)

[0032] For this measurement, the spectrophotometer should be set to receive a 2 nm band pass. A higher FOM means that the nanocomposite does a better job of absorbing infrared light at 1100 nm while remaining transparent to visible light at 550 nm. The FOM is strongly affected by both the particle size and particle composition, although the FOM is not strongly affected by the nanoparticle loading in the nanocomposite.

[0033] For example, in some embodiments, the antimony tin oxide nanoparticles, which, when dispersed at 0.05 wt% (500 ppm) in ethylene glycol, have a figure of merit greater than or equal to 0.50.

[0034] In some embodiments, the FOM is greater than or equal to 0.75. In some embodiments, the FOM is greater than or equal to 1.0. In some embodiments, the

FOM is greater than or equal to 1.25. In some embodiments, the FOM is greater than or equal to 1.5. In some embodiments, the FOM is greater than or equal to 1.75. In some embodiments, the FOM is greater than or equal to 2.0. In some embodiments, the FOM is greater than or equal to 10.0. In some embodiments, the FOM merit ranges from 2.0 to 5.0.

[0035] In any embodiment, a range of particle size distributions may be useful as explained here. The particle size distribution, as used herein, may be expressed by the following ratio: D90/D50, where D90 represents a particle size in which 90% of the volume of ATO nanoparticles have a diameter smaller than the stated D90; and D50 represents a particle size in which 50% of the volume of ATO nanoparticles have a diameter smaller than the stated D50. For example, if D90 is 90 nm, and D50 is 60 nm, then D90/D50 is 1.5. For the same antimony tin oxide particle composition and average particle size, a composition with a lower D90/D50 will, in general, have a higher Figure-of-Merit.

[0036] In some embodiments, the antimony tin oxide nanoparticles have a particle size distribution, as measured by the ratio of D90/D50, less than or equal to 2.0. In some embodiments, the particle size distribution is less than or equal to 1.5. In some embodiments, the particle size distribution ranges from 1.5 to 3.0. In some embodiments, the particle size distribution ranges from 1.75 to 2.25.

[0037] In any embodiment, the ATO nanoparticles may have different average particle size. For example, in some embodiments, the mean particle size equals less than 50 nm. In some embodiments, the mean particle size equals less than 20 nm. In some embodiments, the mean particle size ranges from 5 to 250 nm. In some embodiments, the mean particle size ranges from 30 to 100 nm. In some embodiments, the mean particle size ranges from 5 to 100 nm. In some embodiments, the mean particle size ranges from 5 to 30 nm. In some embodiments, the mean particle size ranges from 100 to 250 nm.

[0038] In any of the embodiments, the ATO nanoparticles may be stoichiometric or non-stoichiometric.

[0039] In some embodiments, the invention is a nanocomposite comprising any embodiment of the ATO nanoparticles in a medium suitable for energy transfer.

[0040] In some embodiments, the medium suitable for energy transfer is an aqueous or solvent based ink or coating formulation. In some embodiments, the ink or coating is transparent, in other embodiments it is light colored.

[0041] In some embodiments, the medium suitable for energy transfer is a polymer or a monomer. The polymer, in some embodiments, is any polymer that is suitable to produce a molded article or preform. The monomers are likewise those monomers capable of making any polymer that is suitable to produce a molded article or a preform. In some embodiments, the polymers are selected from polyesters such as polycarbonate, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). In other embodiments, the medium suitable for energy transfer comprises a monomer used to make polyesters, such as polycarbonate, PET and PEN. In other embodiments, the polymers are copolyesters and blends of PET and PEN. [0042] In some embodiments, the medium suitable for energy transfer is a monomer or polymer that is a polyester, and in some embodiments (PET), (PEN) or copolyesters or blends of PET and PEN. In some embodiments, the polyethylene terephthalate resin contains repeat units from at least 85 mole percent terephthalic acid and at least 85 mole percent ethylene glycol, while in some embodiments, the PEN resin contains repeat units from at least 85 mole percent 2,6-naphthalene- dicarboxlic acid and at least 85% ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol.

[0043] In some embodiments, the dicarboxylic acid component of the polyester may optionally be modified with up to about 15 mole percent of one or more different dicarboxylic acids other than terephthalic acid or suitable synthetic equivalents such as dimethyl terephthalate. In some embodiments, such additional dicarboxylic acids include aromatic dicarboxylic acids preferably having 8 to 14 carbon atoms, aliphatic dicarboxylic acids preferably having 4 to 12 carbon atoms, or cycloaliphatic dicarboxylic acids preferably having 8 to 12 carbon atoms. In some embodiments, examples of dicarboxylic acids to be included with terephthalic acid are: phthalic acid, isophthalic acid, naphthalenedicarboxylic acid (including, but not limited to the 2,6-isomer), cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'- dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid,

and the like. In some embodiments, examples of dicarboxlic acids to be included with naphthalene-2,6-dicarboxylic acid are phthalic acid, terephthalic acid, isophthalic acid, other isomers of naphthlenedicarboxylic acid, cyclohexane-dicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4"-dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and the like. In some embodiments, polyesters may be prepared from two or more of the above dicarboxylic acids. [0044] In some embodiments, it should be understood that use of the corresponding acid anhydrides, esters, and acid chlorides of these acids is included in the term "dicarboxylic acid."

[0045] In addition, in some embodiments, the polyester component may optionally be modified with up to about 15 mole percent, of one or more different diols other than ethylene glycol. Such additional diols include cycloaliphatic diols preferably having 6 to 20 carbon atoms or aliphatic diols preferably having 3 to 20 carbon atoms. Examples of such diols to be included with ethylene glycol are: diethylene glycol, triethylene glycol, 1 ,4-cyclohexanedimethanol, propane- 1, 3 -diol, butane- 1,2-diol, pentane-l,5-diol, hexane-l,6-diol, 3-methylpentanediol-(2,4), 2-methylpentanediol- (1,4), 2,2,4-trimethylpentane-diol-(l,3), 2-ethylhexanediol-(l,3), 2,2-diethylpropane- diol-(l,3), hexanediol-(l,3), 1 ,4-di-(hydroxyethoxy)-benzene, 2,2-bis-(4-hydroxy- cyclohexyl)-propane, 2,4-dihydroxy-l,l,3,3-tetramethyl-cyclobutane, 2,2-bis-(3- hydroxyethoxyphenyl)-propane, and 2,2-bis-(4-hydroxypropoxyphenyl)-propane. In some embodiments, polyesters may be prepared from two or more of the above diols. [0046] In some embodiments, the polyethylene terephthalate resin may also contain small amounts of trifunctional or tetrafunctional comonomers such as trimellitic anhydride, trimethylolpropane, pyromellitic dianhydride, pentaerythritol, and other polyester forming polyacids or polyols generally known.

[0047] In some embodiments, the PET polyesters comprise at least about 90 mole % terephthalic acid or dimethyl terephthalate and about 90 mole % ethylene glycol residues

[0048] In some embodiments, polyethylene terephthalate based polyesters may be prepared by conventional polycondensation procedures well-known in the art. In some embodiments, such processes include direct condensation of the dicarboxylic

acid(s) with the diol(s) or by ester interchange using a dialkyl dicarboxylate. For example, in some embodiments, a dialkyl terephthalate such as dimethyl terephthalate is ester interchanged with the diol(s) at elevated temperatures in the presence of a catalyst. In some embodiments, the polyesters may also be subjected to solid state polymerization methods. In some embodiments, PEN polyesters may also be prepared by well known polycondensation procedures.

[0049] In some embodiments, the medium suitable for energy transfer is chosen from organic polymers and organic monomers. In some embodiments, the organic polymers are chosen from polyesters. In some embodiments, the polyesters are chosen from polyethylene terephthalates. In some embodiments, the polymers are chosen from polypropylene and monomers thereof. In some embodiments, the polypropylene is biaxially oriented polypropylene. In some embodiments, the polymers and monomers are chosen from propylene homopolymers; random copolymers of propylene and α-olefms, which in some embodiments are ethylene; and propylene homopolymer/propylene-α-olefm copolymer. In some embodiments, the organic polymers and monomers are chosen from poly(ethylene terephthalate), polycarbonate, polypropylene, polyethylene, cyclic polyolefm's, Norborne polymers, polystyrene, syndiotactic polystyrene, styrene-acrylate copolymers, acrylonitrile- styrene copolymers, poly(ethylene naphthalate), polyethersulfone, polysulfone, polyamides, including nylons, poly(urethanes), acrylics, cellulose acetates, cellulose triacetates, vinyl chloride polymers, polyvinyl fluoride, polyvinylidene fluoride, poly(ethylene-co-vinyl acetate); ethyl acrylic acetate (EM); ethyl methacrylate (EMAC); metallocene-catalyzed polyethylene; plasticized poly(vinyl chloride); ISD resins; polyurethane; acoustically modified poly( vinyl chloride), an example of which is commercially available from the Sekisui Company; plasticized poly(vinyl butyral); acoustically modified poly( vinyl butyral); and the like and copolymers thereof and blends thereof and monomers thereof. In some embodiments, the polymers and monomers are chosen from resins, which, in some embodiments, may be chosen from any naturally occurring or synthetic polymer prepared by polymerization, polycondensation or polyaddition, such as polyethylene, polypropylene, polyisobutylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl

acetals, polyacrylonitrile, polyacrylates, polymethacrylates, polybutadiene, ABS, ethylene vinyl acetate, polyamides, polyimides, polyoxymethylene, polysulfones, polyphenylene sulfide, polycarbonates, polyurethanes, polyethers, polyether sulfones, polyacetals, phenolics, polycarbonate, polyester carbonate, polyethylene terephthalate, polybutylene terephthalate, polyarylates, polyether ketones, and blends thereof, copolymers thereof, and monomers thereof. In some embodiments, the polymers and monomers are chosen from polyvinylbutyrals and monomers thereof. In some embodiments, the polyvinylbutyrals are chosen from those containing from about 17 to 23% by weight of vinyl alcohol units, and in some embodiments those containing from 20 to 21% by weight of vinyl alcohol units.

[0050] The medium suitable for energy transfer can also be formulated into coating compositions as is well known in the art and applied by known coating techniques to any type of substrate. In some embodiments, the substrate is chosen from plastic, metal, glass, ceramic, wood, upholstery, carpets, and textiles. In some embodiments, the substrate is coated, associated with adhesive, varnishes, papers, and/or inks. [0051] In any nanocomposites embodiment, one or more other ingredients may be added. For example, in some embodiments, the one or more other ingredients are chosen from crystallization aids, impact modifiers, surface lubricants, denesting agents, stabilizers, antioxidants, ultraviolet light absorbing agents, deactivators, colorants, nucleating agents, fillers, acetaldehyde reducing compounds, other reheat enhancing aids, and anti-abrasion additives. In some embodiments, the polymer resin may also contain one or more branching agents, such as trifunctional and tetrafunctional comonomers such as trimellitic anhydride, trimethylol propane, pyromellitic dianhydride, pentaerythritol, and other polyester forming polyacids or polyols generally known in the art.

[0052] A variety of other articles can be made from any of the embodiments of the ATO nanoparticles and/or the nanocomposite comprising the ATO nanoparticles. In some embodiments, the articles are those in which reheat is neither necessary nor desirable. In some embodiments, articles include sheet, film, bottles, trays, other packaging, rods, tubes, lids, fibers and injection molded articles. In one embodiment, there is provided a beverage bottle containing and/or suitable for holding substances

like a liquid. In another embodiment, there is provided a heat-set beverage bottle containing and/or suitable for holding beverages which are hot-filled into the bottle. In yet another embodiment, the bottle is containing and/or suitable for holding carbonated soft drinks. Further, in yet another embodiment, the bottle is containing and/or suitable for holding alcoholic beverages. In some embodiments, there is provided a preform. In some embodiments, there is provided a container containing a preform.

[0053] In any embodiment, the medium suitable for energy transfer contains a plasticizers. In some embodiments, the plasticizer is dihexyl adipate, phosphoric acid ester and phthalic acid ester. In some embodiments, the plasticizer concentrations ranges up to 35% by weight of the mediums suitable for energy transfer. [0054] In any embodiment, the ATO nanoparticles may be made by any method. One of skill in the art is readily aware of methods of forming nanoparticles. For example the following references, which are specifically incorporated herein by reference, all teach methods of forming nanoparticles that may be used to form IR absorbing nanoparticles: U.S. Patent No. 5,788,738 to Pirzada et al; U.S. Patent No. 5,851,507 to Pirzada et al.; U.S. Patent No. 6,602,595 to Yadav et al.; U.S. Published Patent Appl. No. 2006/0099146 to Chow et al. (published 11 May 2006). [0055] In any embodiment, the ATO nanoparticles may be made by a high temperature gas phase method. Example high temperature processes include, but are not limited to, combustion processes, plasma processes, laser ablation processes, calcining and grinding processes and combinations of these processes. [0056] In any embodiment, the ATO nanoparticles may be made by a wet chemistry method. Example wet chemistry processes include, but are not limited to, sol-gel processes, precipitation processes, wet grinding processes, inverse-micelle methods, and combinations of these processes. See, e.g., Beck and Siegel, "The Dissociative Adsorption of Hydrogen Sulfide over Nanophase Titanium Dioxide," J. Mater. Res., 7, 2840 (1992), and Steigerwald and Brus, "Synthesis, Stabilization, and Electronic Structure of Quantum Semiconductor Nanoclusters," Ann. Rev. Mater. ScL, 19, 471 (1989).

[0057] In any embodiment, the ATO nanoparticles may be made by a method using organometallic containing liquids as precursors. See, e.g., U.S. Pat. No. 5,984,997 assigned on its face to Nanomaterials Research Corporation, now NanoProducts

Corporation, which patent is incorporated herein by reference.

[0058] In any embodiment, the ATO nanoparticles may be made by a method utilizing chlorides. See, e.g., U.S. Pat. No. 6,695,907 assigned on its face to

DeGaussa, which is incorporated herein by reference.

[0059] In any of the embodiments, the percentage of antimony in the ATO nanoparticles may be adjusted by routinely varying the amount of antimony to the reacting system.

[0060] In any of the embodiments, the figure of merit (FOM) may be adjusted by choosing the right combination of average particle size and the right antimony content.

[0061] In any of the embodiments, the D90/D50 ratio may be determined by a photosedimentation technique, such as measured by the LumiSizer instrument, sold by Lumi GMBH. Also, in any of the embodiments, the D90/D50 ratio may be varied by operating the nanoparticle production process to ensure homogenous conditions within the particle forming region of the process..

[0062] In any of the embodiments, the average size of the ATO nanoparticles may be determined by calculating the equivalent spherical diameter from the BET nitrogen surface area[ Adjustment technique depends strongly on the production process).

[0063] Any embodiment of the ATO nanoparticles may be introduced to a medium suitable for energy transfer (The energy transfer is from the photoexcited ATO nanoparticles to the medium suitable for energy transfer.). The introducing could be done by chemical or mechanical methods.

[0064] For example, any embodiment of the ATO nanoparticles may be introduced to a polymer or introduced to monomers before or during their polymerization at a suitable time and location. Furthermore, any embodiment of the ATO nanoparticles may be introduced to a polymer or introduced to a monomer by mechanical mixing, shaking, stirring, grinding, ultrasound, etc., with or without the aid of a solvent system.

[0065] The amount of ATO nanoparticles used in the medium suitable for energy transfer will depend upon the particular application, the desired reduction in reheat time, and the toleration level in optical properties. In some embodiments, the amount of ATO nanoparticles may be at least 0.5 ppm or at least 1 ppm or at least 5 ppm. In some embodiments, the amount may be at least 10 ppm, in some cases at least 20 ppm, or even at least 25 ppm. In some embodiments, the amount may be up to 500 ppm or more, or up to about 300 ppm, or up to about 250 ppm. In some embodiments, the amount may be up to 1,000 ppm, or up to 5,000 ppm, or even up to 10,000 ppm or the amount may even exceed 10,000 ppm.

[0066] In some embodiments, the method by which the ATO nanoparticles are introduced to the medium suitable for energy transfer may be illustrated by the following. In some embodiments, the ATO nanoparticles may be added to a polymer reactant system, during or after polymerization, to a polymer melt, or to a molding powder or pellets or molten polyester in the injection-molding machine from which the bottle preforms are made. In some embodiments, the ATO nanoparticles may be added at locations including proximate the inlet to an esterification reactor, proximate the outlet of an esterification reactor, at a point between the inlet and the outlet of an esterification reactor, anywhere along a recirculation loop, proximate the inlet to a prepolymer reactor, proximate the outlet to a prepolymer reactor, at a point between the inlet and the outlet of a prepolymer reactor, proximate the inlet to a polycondensation reactor, or at a point between the inlet and the outlet of a polycondensation reactor, or at a point between the outlet of a polycondensation reactor and a die for forming pellets, sheets, fibers, or bottle preforms. [0067] In some embodiments, the ATO nanoparticles may be added to a polyester polymer, such as PET, and fed to an injection molding machine by any method, including feeding the ATO nanoparticles to the molten polymer in the injection molding machine, or by combining the ATO nanoparticles with a feed of PET to the injection molding machine, either by melt blending or by dry blending pellets. The ATO nanoparticles may be supplied as-is, or in a concentrate form in a polymer such as PET, or as a dispersion in a liquid or solid carrier. In some embodiments,

examples of suitable carriers include polyethylene glycol, mineral oil, hydrogenated castor oil, and glycerol monostearate.

[0068] Alternatively, the ATO nanoparticles may be added to an esterification reactor, such as with and through the ethylene glycol feed optionally combined with phosphoric acid, to a prepolymer reactor, to a polycondensation reactor, or to solid pellets in a reactor for solid stating, or at any point in-between any of these stages. In some embodiments, the ATO nanoparticles may be combined with PET or its precursors as-is, as a concentrate containing PET, or diluted with a carrier. In some embodiments, the carrier may be reactive to PET or may be non-reactive. In some embodiments, the ATO nanoparticles, whether neat or in a concentrate or in a carrier, and the bulk polyester, may be dried prior to mixing together. In some embodiments, the ATO nanoparticles may be dried in an atmosphere of dried air or other inert gas, such as nitrogen, and if desired, under sub-atmospheric pressure. [0069] The polyester compositions of the present invention may be used to form preforms used for preparing packaging containers. The preform is typically heated above the glass transition temperature of the polymer composition by passing the preform through a bank of quartz infrared heating lamps, positioning the preform in a bottle mold, and then blowing pressurized air through the open end of the mold. [0070] In reheat blow-molding, bottle preforms, which are test-tube shaped injection moldings, are heated above the glass transition temperature of the polymer, and then positioned in a bottle mold to receive pressurized air through their open end. This technology is well known in the art, as shown, for example in U.S. Pat. No. 3,733,309, incorporated herein by reference. In a typical blow-molding operation, radiation energy from quartz infrared heaters is generally used to reheat the preforms. [0071] Because the ATO nanoparticles can be made substantially transparent to visible light, addition of these particles to coatings, adhesives, varnishes, papers, and inks does not alter the transparency or color of these materials. In addition, the small size of the ATO nanoparticles allows them to be distributed homogeneously in the coatings, adhesives, varnishes, papers, and inks and allows lower loading, which reduces costs.

[0072] In some embodiments, the present invention provides coatings, adhesives, varnishes, papers, and inks comprising the ATO nanoparticles described herein. The coatings, adhesives, varnishes, papers, and inks can contain one or more blends of ATO nanoparticles and/or composites comprising the ATO nanoparticles. The ATO nanoparticles and/or composites comprising the ATO nanoparticles can be mixed with the coatings, adhesives, varnishes, papers, and inks or applied to the surface of the coatings, adhesives, varnishes, papers, and inks. For example, the ATO nanoparticles and/or composites comprising the ATO nanoparticles can be mixed with the coatings, adhesives, varnishes, papers, and inks during manufacturing or can be sprayed on the coatings, adhesives, varnishes, papers, and inks after they are applied to a substrate. The ATO nanoparticles and/or composites comprising the ATO nanoparticles can be added at any time. For example, the ATO nanoparticles and/or composites comprising the ATO nanoparticles can be added by an end user, such as by mixing with the coating, adhesive, or ink or spraying the ATO nanoparticles and/or composites comprising the ATO nanoparticles on the coating, adhesive, or ink. [0073] One of skill in the art can readily select the amount of ATO nanoparticles and/or composites comprising the ATO nanoparticles to add to the composition depending on the particular application. For example, an curing or drying process required large amounts of IR energy may require addition of a large amount of ATO nanoparticles and/or composites comprising the ATO nanoparticles. Generally, the IR absorption increases linearly as the amount of ATO nanoparticles is increased. In some embodiments, the ATO nanoparticles can be present in the coatings, adhesives, varnishes, papers, and inks in amount of less than 0.005 wt. %, less than 0.01 wt. %, less than 0.02 wt. %, or less than 0.1 wt. %.

[0074] In some embodiments, the ATO nanoparticles can be functionalized depending on the particular application. For example, the ATO nanoparticles can be functionalized to bind or, in some embodiments, associate with a particular component of the coating, adhesive, or ink. Such functionalization can speed polymerization by causing the ATO nanoparticles to associate with monomers to be polymerized. As another example, the surface of the nanoparticles can be functionalized to be hydrophobic, hydrophilic, lipophilic, or lipophobic. Such ATO

nanoparticles can in some embodiments associate with some liquid component that is intended to be evaporated during drying. The ATO nanoparticles can also be functionalized to facilitate their dispersion. By functionalizing ATO nanoparticles, the ATO nanoparticles can be tailored to the particular application resulting in cheaper and more efficient use of coatings, adhesives, varnishes, papers, and inks. [0075] The ATO nanoparticles may also absorb energy from parts of the electromagnetic spectrum other than infrared. For example, the ATO nanoparticles may also absorb ultraviolet energy. Nanoparticles that absorb both IR energy and UV energy may be used in application where the coating, adhesive, or ink should be resistant to UV energy. Because the ATO nanoparticles can also absorb UV in addition to IR energy, they may slow or prevent degradation commonly caused by UV radiation. The resulting coating or adhesive can also prevent heat from passing through the material. This application may be useful in applications where the coating is used to prevent the coated item from being heated or exposed to UV energy or energy from other portions of the electromagnetic spectrum. Thus, IR absorbing nanoparticles that absorb both UV and IR energy can assist in curing or drying and improve the long-term performance of the coating, adhesive or ink. In some embodiments, the ATO nanoparticles absorb at least 50%, at least 75%, at least 85%, at least 90%, at least 95%, or at least 100% as much energy from a second portion of the UV electromagnetic spectrum as they absorb from the IR spectrum. [0076] The ATO nanoparticles and/or composites comprising the ATO nanoparticles can be added to any type of coating, adhesive, or ink that can be cured or dried using IR energy. In some embodiments, the coating, adhesive, or ink must retain its optical properties, such as color and transparency. For example, the coating can be a clear coat or a color coat used in an automotive finishing process. Because, in some embodiments, the ATO nanoparticles and/or composites comprising the ATO nanoparticles do not absorb significant amounts of light in the visible spectrum, they can be used in clear coat and color coat applications. The ability of the ATO nanoparticles and/or composites comprising the ATO nanoparticles to transmit visible light also make them suited to use with inks. Many adhesives must also retain one or more of their optical properties, such as retaining transparency, so ATO nanoparticles

and/or composites comprising the ATO nanoparticles are also useful in these applications.

[0077] In some embodiments, the present invention also provides methods of drying or curing coatings, inks, and adhesives using IR energy. Because the ATO nanoparticles absorb IR energy, the IR energy may be transferred to the medium suitable for energy transfer in the form of heat. Thus, the ATO nanoparticles and/or composites comprising the ATO nanoparticles can result in faster curing compared to curing coatings, inks, or adhesives without using the ATO nanoparticles and/or composites comprising the ATO nanoparticles. The method can also result in more efficient or effective curing compared to curing coatings, inks, or adhesives without using the ATO nanoparticles and/or composites comprising the ATO nanoparticles. Thus, the present invention provides an method of drying or curing coatings, inks, and adhesives that can speed processes, reduce costs, and result in coatings, inks, and adhesives with improves properties.

[0078] In some embodiments, the method comprises contacting a coating, ink, or adhesive with the ATO nanoparticles and/or composites comprising the ATO nanoparticles and exposing the coating, ink, or adhesive to IR energy. The contacting can occur in any manner. In some embodiments, the ATO nanoparticles can be mixed with at least one component of the coating, ink, or adhesive, such as one of more pigments, fillers, binders, solvents, or carriers. For example, many coatings, inks, and adhesives contain a polymer or similar material which functions as a binder for pigment or as the actual coating, ink, or adhesive itself. The ATO nanoparticles and/or composites comprising the ATO nanoparticles can be dispersed into the monomer composition used to make the polymer, thereby achieving uniform dispersion throughout the polymer and intimate contact in the final formulation of the coating, ink, or adhesive.

[0079] In other embodiments, the contacting can occur by applying the ATO nanoparticles and/or composites comprising the ATO nanoparticles to at least one surface of the coating, ink, or adhesive. For example, the ATO nanoparticles can be sprayed onto the coating, ink, or adhesive. The contacting can also occur by applying the ATO nanoparticles and/or composites comprising the ATO nanoparticles to a

substrate followed by applying the coating, ink, or adhesive to the substrate. The ATO nanoparticles and/or composites comprising the ATO nanoparticles can be in powder form or dispersed into a solvent or carrier.

[0080] In other embodiments, the contacting can occur by forming a film or sheet from the ATO nanoparticles and/or composites comprising the ATO nanoparticles. This film or sheet can then be applied to the coating, adhesive, ink, or substrate followed by application of IR energy. In some embodiments, this film or sheet can be used multiple times. For example, the sheet or film can be prepared to match the shape of the substrate and used multiple times to apply one or more coatings, adhesives, varnishes, papers, and inks to the substrate. [0081] In some embodiments, the method comprises removing the ATO nanoparticles and/or composites comprising the ATO nanoparticles after some period of exposure to IR energy. For example, if the ATO nanoparticles and/or composites comprising the ATO nanoparticles are formed into a film or sheet, this film or sheet can be removed once the IR energy has been applied. In some embodiments, the ATO nanoparticles and/or composites comprising the ATO nanoparticles can be simply washed off the surface of the coating, adhesive, or ink. In some embodiments, the ATO nanoparticles and/or composites comprising the ATO nanoparticles are not removed and remain a part of the coating, adhesive, or ink.

[0082] The IR energy can be applied in any manner. In some embodiments, the IR energy is applied using an IR heat source, such as an IR lamp. IR lamps are commonly used and available to one of skill in the art. Ambient IR energy is suitable. The IR energy can also be applied by simply exposing the coating, adhesive, or ink to some other light source. The other light source an be the light emitted by standard fluorescent lights or even sun light. Thus, the IR energy can be supplied in any manner, as long as the IR energy is sufficient to at least partially affect the curing or drying.

[0083] The method can further comprise applying a second coating, adhesive, or ink. This second coating can be the same or different than the first coating, adhesive, or ink. In some embodiments, the method comprises contacting the second coating, ink, or adhesive with the ATO nanoparticles and/or composites comprising the ATO

nanoparticles and exposing the coating, ink, or adhesive to IR energy. Thus, the method can comprise applying multiple coatings, adhesives, varnishes, papers, and inks, contacting one or more of the coatings, adhesives, varnishes, papers, and inks with ATO nanoparticles and/or composites comprising the ATO nanoparticles, and exposing the one or more of the coatings, adhesives, varnishes, papers, and inks to IR energy.

[0084] In some embodiments, the ATO nanoparticles and/or composites comprising the ATO nanoparticles are used to facilitate laser marking of articles suitable for laser marking. See, e.g., U.S. Patent No. 7,187,396, assigned on its face to Engelhard Corporation, which patent is explicitly incorporated herein by reference. In some embodiments, the articles suitable for laser marking are chosen from plastic articles suitable for laser marking, which in some embodiments include any plastic articles that are molded, extruded or formed by any known conventional method. In some embodiments, the articles suitable for laser marking comprise the ATO nanoparticles and/or composites comprising the ATO nanoparticles and may or may not further comprise other additives. In some embodiments, the other additives are chosen from reinforcing fillers, flame retardants, antioxidants, dispersants, impact modifiers, ultraviolet stabilizers, plasticizers, and the like.

[0085] In some embodiments, the ATO nanoparticles and/or composites comprising the ATO nanoparticles may be incorporated into plastic coatings, including coatings, varnishes, and inks. Such coatings or inks can be applied onto the surface of any article such as those formed of plastic, metal, glass, ceramic, wood. Thus, the plastic coatings containing the ATO nanoparticles and/or composites comprising the ATO nanoparticles make it possible to use of lasers to mark various types of substrates. [0086] In some embodiments of laser marking, any laser can be employed. In some embodiments, the laser has a wavelength ranging from 780 nm to 2000 nm, or the range from 380 nm to 780 nm, or the range 150 nm to 380 nm (each wavelength includes harmonics and summing). In some embodiments, suitable lasers are chosen from solid state pulsed or cw lasers, pulsed or cw metal vapor lasers, excimer lasers and continuous wave lasers with pulse modification, such as the commercially available Nd: YAG laser (wavelength 1064 nm), frequency-doubled Nd: YAG laser

(wavelength 532 nm plus other harmonics and sums), excimer laser (wavelengths depending on excimer, e.g., 193 nm, 351 nm, etc.), CO 2 laser (9.4-10.6 μm), titanium sapphire (from about 650 to 1100 nm)

Example 1.

[0087] We have found that the infrared absorbance of antimony tin oxide nanoparticles can be improved (increased) at higher antimony levels than the previously preferred range. Table 1 shows the infrared absorbance (extinction) of

0.05 wt% nanoparticles dispersed in ethylene glycol, measured at an infrared wavelength of 1100 nm, using a Perkin-Elmer spectrophotometer, operated in transmittance mode.

Table 1

Extinction of 0.05 wt% antimony-doped tin oxide nanoparticles in ethylene glycol at 1100 nm versus antimony content

Antimony Infrared

2% Sb 0.170

8% Sb 0.166

16% Sb 0.398

20% Sb 0.450

25% Sb 0.550

[0088] The table shows that the infrared extinction is improved at 20% and 25% antimony, compared to 8% antimony.

Example 2.

[0089] By way of comparison, a number of materials were tested to determine the

IR absorption properties of the materials. Specifically, nanoparticles of reduced indium tin oxide (rITO) and antimony tin oxide (New Material) were prepared.

Carbon black was also used. The materials were dispersed in ethylene glycol in differing percentages reduced indium tin oxide (0.025% and 0.05%), antimony tin oxide (0.1%), and carbon black (0.005%, 0.01%, 0.02%). Results are in Figure 1.

[0090] As seen in Figure 1 , carbon black absorbed IR energy, but it also absorbed energy in the visible spectrum. Thus, carbon black would be expected to alter the optical properties of a material to which it is added. On the other hand, the

nanoparticles of reduced indium tin oxide and antimony tin oxide also absorbed IR energy, but they absorbed very little energy in the visible spectrum. Thus, these IR absorbing nanoparticles can be used to increase optical absorption without disrupting the optical properties of a material to which they are added.

Example 3.

[0091] For this example, the 16% Sb antimony-doped tin oxide nanoparticles were used. We have further found that the visible absorbance can be improved (decreased) at smaller particle sizes. Table 2 shows the visible absorbance (extinction) of 0.05 wt% nanoparticles dispersed in ethylene glycol at a visible wavelength of 550 nm, using a Perkin-Elmer spectrophotometer, operated in transmittance mode.

Table 2

Extinction of 0.05 wt% antimony-doped tin oxide nanoparticles in ethylene glycol at 550 nm versus particle size

Average

Surface Area Particle Size Visible Extinction

90.4 m2/g 9.6 nm 0.29

52.8 m2/g 17.8 nm 0.39

24. 2 m2/g 35 .7 nm 0.59

18. 9 m2/g 45 .8 nm 1.10

7.3 m2/g 118. 5 nm 1.74

[0092] The table shows that the visible extinction is improved for particles below 20 nm (above 50 m2/g).

[0093] Tables 1 and 2 show that an improved antimony tin oxide would have both a high antimony content, and a low particle size. This specific combination of particle size and particle composition is needed to give a high ratio of infrared absorbance to visible absorbance.

[0094] Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.