JAMES DAVID (AU)
MATTHEWS WILLIAM (AU)
JAMES DAVID (AU)
| WO2002004527A2 | 2002-01-17 | |||
| WO2001003945A1 | 2001-01-18 | |||
| WO2003006965A1 | 2003-01-23 |
| CA1209341A | 1986-08-12 | |||
| CA1212021A | 1986-09-30 | |||
| GB2381530A | 2003-05-07 | |||
| US5929437A | 1999-07-27 | |||
| US20040106205A1 | 2004-06-03 |
| 1. | A polymeric material comprising a tagging component which is an inert rareearth compound or a mixture of inert rareearth compounds. |
| 2. | A polymeric material according to claim 1 wherein the tagging component is selected from rareearth oxides, rareearth sulfides, rareearth borides, rareearth alkyls, rareearth silicide, rareearth halides, and rareearth mixed metals; and mixtures thereof. |
| 3. | A polymeric material according to claim 1 or claim 2 wherein the tagging component comprises one or more rareearth oxides selected from Neodymium oxide, Neodymium acetate, Neodymium carbonate, Neodymium hydroxide, Neodymium nitrate, Neodymium oxalate, Neodymium sulfate, Yttrium Acetate, Yttrium carbonate, Yttrium nitrate, Yttrium oxalate, Yttrium oxide, Yttrium sulphate, Lanthanum acetate, Lanthanum carbonate, Lanthanum nitrate, Lanthanum oxalate, Lanthanum oxide, Cerium acetate, Cerium ammonium nitrate, Cerium ammonium sulfate, Cerium carbonate, Cerium hydroxide, Cerium nitrate, Cerium oxide, Cerium oxalate, Cerium sulphate, Praseodymium acetate, Praseodymium carbonate, Praseodymium nitrate, Praseodymium oxalate, Praseodymium oxide, Praseodymium sulphate, Samarium acetate, Samarium carbonate, Samarium oxalate, Samarium oxide, Samarium sulphate, Europium acetate, Europium carbonate, Europium nitrate, Europium oxalate, Europium oxide, Europium sulphate, Gadolinium acetate, Gadolinium carbonate, Gadolinium oxalate, Gadolinium nitrate, Gadolinium oxide, Terbium acetate, Terbium carbonate, Terbium nitrate, Terbium oxalate, Terbium sulphate, Dysprosium acetate, Dysprosium carbonate, Dysprosium oxalate, Dysprosium oxide, Dysprosium sulphate, Holmium acetate, Holmium carbonate, Holmium oxalate, Holmium oxide, Holmium sulphate, Erbium acetate, Erbium nitrate, Erbium oxide, Erbium sulphate, Thulium acetate, Thulium carbonate, Thulium nitrate, Thulium oxalate, Thulium oxide, Ytterbium acetate, Ytterbium carbonate, Ytterbium nitrate, Ytterbium oxalate, Ytterbium oxide, Ytterbium sulphate, Lutetium acetate, Lutetium nitrate, Lutetium oxide, Lutetium sulphate, and Scandium oxide. |
| 4. | A polymeric material according to claim 3 wherein the tagging cornponent comprises one or more rareearth oxides selected from those represented by the following formulae: Nd203, Nd (CH3COO) 3. H20, Nd2 (C03) 3.3H20, Nd (OH) 3. 3H20, Nd (N03) 3. 6H20, Nd2 ( (COO) 2) 3. 1OH20, Nd2 (S04) 3. 8H20, Y (CH3COO)3. 4H20, Y2 (C03) 3. 3H20, Y (N03). 3H20, Y2 ( (COO) 2) 3. 10H20, Y203, Y2 (S04) 3. 6H20, La (CH3COO) 3.3H20, La2 (C03). 3H20, La (N03) 3.6H20, La2 ( (COO) 2) 3. 9H20, La203, Ce (CH3COO) 3.xH2O, (NH4)2Ce(NO3)6, Ce(NH4)4.(SO4)4.xH2O, Ce2(CO3)3.xH2O, Ce (OH). |
| 5. | H20, Ce (N03) 3. xH20, Ce02, Ce2 ( (COO) 2) 3.9H20, Ce (S04) 2. xH20, Pr (CH3COO) 3. xH20, Pr (C03) 3. xH20, Pr (N03) 3. xH20, Pr2 ((COO)2) 3. xH20, Pr60n, Pr2 (SO4) 3. 8H20, Sm (CH3COO) 3. xH20, Sm2 (CO2) 3. xH20, Sm ((CO0) 2) 3.9H20, Sm203, Sm2(SO4) 3. 8H20, Eu (CH3COO) 3. xH20, Eu2 (C03) 3. xH2O, Eu (N03) 3. 6H20, Eu2 ((COO)2) 3. xH20, Eu203, Eu2 (SO2) 3. 8H20, Gd (CH3C00) 3.4H20, Gd2 (C03) 3. xH2O, Gd ( (COO) 2) 3. 10H20, Gd (N03) 3. H20, Gd2O3, Tb (CH3C00) 3. xH20, Tb2 (CO3) 3. xH20, Tb (N03) 3. xH20, Tb2 ((COO)2) 3. 10H20, Tb2 (S04) 3. 8H20, Tb4O7, Dy2 (CH3COO)3. xH20, Dy2 (C03) 3. xH20, Dy2 ( (COO) 2) 3. 10H2O, Dy203, Dy2 (S04) 3.6H20, Ho (CH3COO)3.xH2O, Ho2 (CO3) 3. xH20, Ho2 ( (COO) 2) 3. 6H20, Ho2O3, Ho2 (SO4) 3. 6H20, Er (CH3COO)3.xH2O, Er (N03) 3. 5H20, Er203, Er2 (S04) 3.8H20, Tm (CH3COO) 3. xH20, Tm2 (CO3) 3. H20, Tm(NO3)3.xH2O, Tm2((COO)2) 3.6H20, Tm203, Yb (CH3COO) 3.4H20, Yb2 (CO3) 3. xH2O, Yb (N03) 3. xH20, Yb2 ( (COO) 2) 3. 1OH20, Yb203, Yb2 (SO4) 3. 6H20, Lu (CH3COO) 3. xH20, Lu (N03) 3. H20, Lu203, Lu2 (S04). |
| 6. | 8H20, and Sc203. |
| 7. | A polymeric material according to claim 4 wherein the tagging component comprises one or more rareearth oxides selected from those represented by the formulae : Nd203, Dy2O3, H0203, Ce02, Pr6011, Sm203, Eu203, Gd203, Er203, Yb203, Lua03, Tm203, Sc2O3, Y203, La203, and Tb407. |
| 8. | A polymeric material according to claim 5 wherein the tagging component comprises one or more rareearth oxides selected from those represented by formulae: Y203, La203, Eu2O3, Gd203, Dy203, Ho2O3, Yb203, and Lu203. |
| 9. | A polymeric material according to claim 6 wherein the tagging component comprises one or more rareearth oxides selected from those represented by formula Y203 and La203. |
| 10. | A polymeric material according to claim 1 or claim 2 wherein the tagging component comprises one or more rareearth mixed metals selected from Yttrium Aluminium Alloys, Cerium Mishmetal, Neodymium Alloys, Samarium Alloys, Dysprosium Alloys, and ScandiumAluminium Alloys. |
| 11. | A polymeric material according to claim 8 wherein the tagging component comprises one or more rareearth mixed metals selected from the formulae YAl, NdDy, NdFe, NdFeDy, NdFeB, SmCo, DyFe, DyCo, and ScAl. |
| 12. | A polymeric material according to claim 1 or claim 2 wherein the tagging component comprises Lanthanum boride. |
| 13. | A polymeric material according to claim 1 or 2 wherein the tagging component comprises Cerium sulfide. |
| 14. | A polymeric material according to claim 1 or claim 2 wherein the tagging component comprises one or more inert rareearth a rareearth halides selected from Neodymium chloride, Neodymium fluoride, Yttrium chloride, Yttrium fluoride, Lanthanum chloride, Lanthanum fluoride, Cerium chloride, Cerium fluoride, Praseodymium chloride, Praseodymium fluoride, Samarium chloride, Samarium fluoride, Europium chloride, Europium fluoride, Gadolinium chloride, Gadolinium fluoride, Terbium chloride, Terbium fluoride, Dysprosium chloride, Dysprosium fluoride, Holmium chloride, Holmium fluoride, Erbium chloride, Erbium fluoride, Thulium chloride, Thulium fluoride, Ytterbium chloride, Ytterbium fluoride, Lutetium chloride, Lutetium fluoride, and Scandium fluoride. |
| 15. | A polymeric material according to claim 12 wherein the tagging component comprises one or more rareearth halides selected from those represented by the following formulae: NdCl3. 6H20, NdF3, YCl3. 6H20, YF3, LaCl3. xH20, LaF3, CeCl3. xH20, CeF3, PrCl3. xH2O, PrF3, SmCl3. xH2O, SmF3, EuCl3. 6H20, EuF3, GdCl3. 6H20, GdF3, TbCl3. 6H20, TbF3, DyCl3. 6H20, DyF3, HoCl3. 6H20, DyF3, ErCl3. 6H20, ErF3, TmCl3. 7H20, TmF3, YbCl3. 6H20, YbF3, LuCl3. 6H20, LuF3, and ScF3. |
| 16. | A polymeric material according to any one of claims 1 to 13 wherein the tagging component is present in an amount of from about 0.0001 to about 2.0% by weight of the total polymeric material. |
| 17. | A polymeric material according to claim 14 wherein the tagging component is present in an amount of from 0. 001 to 0. 1 % by weight of the total polymeric material. |
| 18. | A polymeric material according to any one of claims 1 to 15 wherein the polymeric material includes a mixture of two inert rareearth compounds with a mixing ratio of from 1: 0.1 to 1: 10. |
| 19. | A polymeric material according to claim 16 wherein the mixing ratio is from 1: 0.1 to 1: 3. |
| 20. | A polymeric material according to any one of claims 1 to 17 which is in the form of a manufactured article or processed article. |
| 21. | A polymeric material according to claim 18 which is a processed article selected from apparel; home, commercial and office furnishings ; housewares; tanks and pipes; composite wood panels; paints; adhesives; coating powders for powder coating applications; architectural extrusion components; industrial/automotive products; medical articles; and packaging. |
| 22. | A polymeric material according to claim 19 wherein the processed article is a coating powder for powder coating applications. |
| 23. | A polymeric material according to claim 19 wherein the processed article is a composite wood panel. |
| 24. | A polymeric material according to claim 21 wherein the composite wood panel is selected from particle board, medium density fibreboard (MDF), oriented strand board (OSB), plywood and combinations thereof. |
| 25. | A polymeric material according to claim 18 wherein the processed article is a binder composition for use in composite wood panel manufacture. |
| 26. | A polymeric material according to claim 18 wherein the manufactured article is a manufactured polymer. |
| 27. | A polymeric material according to claim 24 wherein the manufactured polymer is selected from thermoplastic and thermosetting polymers. |
| 28. | A polymeric material according to claim 25 wherein the manufactured polymer is selected from polyvinyl chloride, polyolefins, polyesters, polyamides, polysulfones, polyimides, polyether imides, polyether sulfones, polyphenylene sulfides, polyether ketones, polyether ether ketones, ABS resins, polystyrenes, polybutadiene, polyacrylates, polyacrylonitrile, polyacetals, polycarbonates, polyphenylene ethers, ethylenevinyl acetate copolymers, polyvinyl acetate, liquid crystal polymers, ethylenetetrafluoroethylene copolymer, aromatic polyesters, polyvinyl fluoride, polyvinylidene fluoride, polyvinylidene chloride, Teflons, and epoxy, phenolic, alkyds, polyester, fluorocarbon, formaldehyde, polyfunctional amines, polyimide, polyurethane, mineral filled silicone, bis maleimides, cyanate esters, vinyl, benzocyclobutene resins; and blends, copolymers, mixtures, reaction products and composites thereof. |
| 29. | A polymeric material according to claim 26 wherein the manufactured polymer is selected from linear and cyclic polyolefins, polyethylene, chlorinated polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polycyclohexylmethylene terephthalate, hydrogenated polysulfones, hydrogenated polystyrenes, syndiotactic and atactic polystyrenes, polycyclohexyl ethylene, styrene co acrylonitrile, styrenecomaleic anhydride, polymethylmethacrylate, methyl methacrylate polyimide copolymers, 2,6dimethylphenol and copolymers with 2,3, 6trimethylphenol; and blends, copolymers, mixtures, reaction products and composites thereof. |
| 30. | A method for tagging a polymeric material comprising incorporating into the polymeric material a tagging component which is an inert rareearth compound or a mixture of inert rareearth compounds. |
| 31. | A method according to claim 28 wherein the tagging component is incorporated into the polymeric material during a polymer manufacturing process, or during processing of said polymeric material to produce a processed article, or a combination thereof. |
| 32. | A method according to claim 28 or claim 29 wherein the tagging component is dispersed uniformly throughout the polymeric material. |
| 33. | A method according to any one of claims 28 to 30 wherein the polymeric material is a powder coating composition and the tagging component is introduced via one or more premixed intermediates. |
| 34. | A method according to any one of claims 28 to 30 wherein the polymeric material is a composite wood panel composed of a binder composition and cellulosebased particles, and that the tagging component is incorporated into said binder composition. |
| 35. | A tagging system for a polymeric material including: a tagging component which is incorporated into the polymeric material and comprises an inert rareearth compound or mixture of inert rareearth compounds; and a detector to identify the presence of said tagging component in said polymeric material. |
| 36. | A tagging system according to claim 33 wherein the detector is selected from an Atomic Absorption Spectrophotometer, Inductively Coupled PlasmaOptical Emission Spectrophotometer (ICPOES), ICPmass Spectrophotometer (ICPMS), XRay Fluorescence Spectrophotometer (XRF), or by Scanning Electron Microscopy (SEM) with an Energy Dispersive XRay (EDX) Spectrophotometer. |
| 37. | A tagging system according to claim 34 wherein the detector is an ICPOES. |
| 38. | A tagging system according to any one of claims 33 to 35 wherein the polymeric material is a manufactured polymer. |
| 39. | A tagging system according to claim 36 wherein the manufactured polymer is a component of a coating powder for powder coating applications or a component of a binder composition for a composite wood panel. |
| 40. | A tagging system according to claim 37 wherein the manufactured polymer is selected from epoxy, polyester, polyurethane, fluorocarbon, acrylic, PVC, polyamide, polyethylene, polypropylene, fluorocarbon, polyester, and cellulose ester polymer resins and formaldehyde based polymer resins. |
| 41. | A tagging system according to any one of claims 33 to 35 wherein the polymeric material is a processed article. |
| 42. | A tagging system according to claim 37 where the processed article is a powder coat or a composite wood panel. |
| 43. | A tagging system according to any one of claims 33 to 40 wherein the tagging component is present in an amount of from about 0.0001 to about 2.0% by weight of the total polymeric material. 42. A tagging system according to claim 41 wherein the tagging component is present in an amount of from 0. 001 to 0. |
| 44. | 1 % by weight of the total polymeric material. |
| 45. | A tagging system according to any one of claims 33 to 42 wherein further to identifying the presence of the tagging component the detector is capable of quantitatively determining the amount of the tagging component incorporated into said polymeric material and/or the ratio of one inert rareearth compound to another in the tagging component. |
Background of the Invention Identification of polymeric materials is desirable for a variety of applications including recycling, tracking a manufacturing source, anti-piracy protection, and the like.
While, UV, visible, and IR spectroscopy has been used to identify the structural make-up of polymeric materials they are not particularly useful techniques for distinguishing between the same or similar materials derived from different manufacturers. This is because the compositions and quantities of the raw materials (which form the materials) are often very similar. Furthermore, most polymers absorb UV light, and if coloured, also absorb visible light.
Tagging compounds such as near-IR fluorescent dyes have also been used to identify polymeric materials. The applicability of these dyes is generally dependent upon their thermal stability under the temperatures required to manufacture and process the polymeric materials. Many of the fluorescent dyes which are used in such applications impart unwanted colour to the polymer material. These dyes are generally organic based compounds having delocalised electron systems which can be relatively expensive primarily due to complex synthetic protocols. For instance, US 5,461, 136 discloses a method of tagging a thermoplastic polymeric material by incorporating one or more thermally stable, near-IR fluorescent compounds which impart fluorescence capable of being detected by a near infrared radiation detector when exposed to electromagnetic
radiation having wavelengths of about 670-2500nm. The preferred near-IR fluorescent compounds disclosed include phthalocyanine, napthalocyanines and derivatives of squaric acid.
Furthermore, US 6,514, 617 discloses a tagged polymer wherein the tagging material comprises at least one organic fluorophore dye, at least one inorganic fluorophore, at least one organometallic fluorophore, at least one semi-conducting luminescent nanoparticle, or a combination thereof, wherein the tagging material has a temperature stability of at least 350°C, and is detectable via a spectrofluorometer at an excitation wavelength between about 100 nanometers and about 1100 nanometers.
Summary of the Invention The present invention provides a polymeric material comprising a tagging component which is an inert rare-earth compound, or a mixture of inert rare-earth compounds.
The present invention also provides a method for tagging a polymeric material comprising incorporating into the polymeric material a tagging component which is an inert rare-earth compound or a mixture of inert rare-earth compounds.
Description of the Preferred Embodiments As used herein the term"inert rare-earth compound"refers to a compound incorporating a rare-earth element wherein the rare-earth element is in an isotopically stable form and the compound does not display luminescence in the visible region and provides no additional function other than to tag, trace, or label the polymeric material. The rare earth element which is incorporated into the inert rare-earth compounds of the present invention is in an isotopically stable form in that it does not comprise undesirable amounts of radioisotopes. For example, compounds incorporating Promethium (Pm) are excluded from the present invention as all known isotopes are radioactive and therefore not"inert". Accordingly, the presence of the inert rare earth compound into the tagged polymeric material does not
affect the normal physical properties or functioning of the tagged polymeric material.
Phosphorescent and fluorescent compounds, known as phosphors and fluorophores, are able to emit light at various detectable wavelengths upon excitation with energy derived from various sources. Fluorescence and phosphorescence are generally categorised as luminescent behaviour which is the emission of light as a result of a previous non-thermal energy transfer. Various phosphors and fluorophosphors are known which contain a rare- earth element as the luminescent centre. The rare-earth tagging compounds of the present invention do not rely on any luminescent behaviour for identification or their ability to act as a tag. Therefore the inert rare-earth tagging compounds of the present invention do not display sufficient luminescent behaviour to affect the normal physical properties of the polymeric compound.
"Rare-earth"as used herein refers to the elemental group including elements 21 (Scandium, Sc), and 39 (Yttrium, Y) as well as the so called"Lanthanides" ; elements 57 (Lanthanum, La) to 71 (Lutetium, Lu).
A"polymeric material"as used herein refers to a material which has a component which has undergone polymerisation. This includes industrially useful polymers, for example, synthetic polymers such as thermoplastic and thermoset polymer resins as well as natural polymers. The aforementioned thermoplastic and thermoset polymers are typically manufactured by known free radical, ionic addition or condensation polymerisation techniques. These polymeric materials are referred to herein as"manufactured polymers".
In addition the term"polymeric material"also refers to products derived from processing the above mentioned manufactured polymers. In relation to the thermoplastic and thermoset polymer resins, these polymers are processed either by injection moulding, extrusion, blow moulding or calendering (for thermoplastic polymers) and compression moulding, high-pressure lamination, reaction injection moulding, and reinforced plastic moulding (for thermoset polymers). The products derived from processing includes the articles of everyday known use, including apparel, home, commercial and office furnishings, housewares, tanks and pipes, construction material, including composite wood
panels, paints, adhesives, coating powders for powder coating applications, as well as architectural extrusion components, industrial/automotive products, medical articles, packaging and so on. These polymeric materials are referred to herein as"processed articles".
Accordingly, the tagging component of the present invention may serve to tag or label a "manufactured polymer"and/or a"processed article". It will be appreciated that if the tagging component is incorporated during the production of a manufactured polymer and that manufactured polymer is then converted into a processed article then the particular tagging component will be acting as a tag for the manufactured polymer. If however the tagging component is incorporated during the conversion of the manufactured polymer to a processed article then the tagging component will be acting as a tag for the processed article. Furthermore, one may use different combinations of tagging compounds during the manufacture and processing of the polymeric materials and this can serve to identify the origin of the source of both the manufactured polymer as well as the manufacturer of the processed article. The inert rare-earth compounds of the present invention make convenient tagging materials as they are not typically found or used in the preparation of manufactured polymers or the corresponding processed articles.
Examples of"manufactured polymers"which may be prepared to incorporate the tagging components (s) of the present invention include, but are not limited to, the thermoplastic polymers: polyvinyl chloride, polyolefins (such as linear and cyclic polyolefins and polyethylene, chlorinated polyethylene, polypropylene, and the like), polyesters (such as polyethylene terephthalate, polybutylene terephthalate, polycyclohexylmethylene terephthalate, and the like), polyamides, polysulfones (such as hydrogenated polysulfones, and the like), polyimides, polyether imides, polyether sulfones, polyphenylene sulfides, polyether ketones, polyether ether ketones, ABS resins, polystyrenes (such as hydrogenated polystyrenes, syndiotactic and atactic polystyrenes, polycyclohexyl ethylene, styrene-co-acrylonitrile, styrene-co-maleic anhydride, and the like), polybutadiene, polyacrylates (such as polymethylmethacrylate, methyl methacrylate-polyimide copolymers, and the like), polyacrylonitrile, polyacetals, polycarbonates, polyphenylene
ethers (such as those derived from 2, 6-dimethylphenol and copolymers with 2,3, 6- trimethylphenol, and the like), ethylene-vinyl acetate copolymers, polyvinyl acetate, liquid crystal polymers, ethylene-tetrafluoroethylene copolymer, aromatic polyesters, polyvinyl fluoride, polyvinylidene fluoride, polyvinylidene chloride, Teflons; as well as the thermosetting resins: epoxy, phenolic, alkyds, polyester, fluorocarbon, formaldehyde, polyfunctional amines, polyimide, polyurethane, mineral filled silicone, bis-maleimides, cyanate esters, vinyl and benzocyclobutene resins, in addition to blends, copolymers, mixtures, reaction products and composites comprising at least one of the foregoing types of polymers.
Preferred inert rare-earth tagging compound (s) of the present invention are selected from: rare-earth oxides which also include oxysulfides, alkoxides, hydroxides, carbonates, nitrates, silicates, phosphates, sulfates, titanates and zirconates; rare-earth sulfides; rare-earth borides; rare-earth alkyls, for example rare-earth organometallics; rare-earth silicides; and rare-earth halides, for example rare-earth chlorides and fluorides; and rare-earth mixed metals, for example alloys and mischmetals.
Examples of rare-earth oxides include: Neodymium oxide (preferably the commercially available compound with the formula Nd203), Neodymium acetate (preferably the commercially available compound with the formula Nd (CH3CO0) 3. H20), Neodymium carbonate (preferably the commercially available compound with the formula Nd2 (CO3) 3. 3H20), Neodymium hydroxide (preferably the commercially available compound with the formula Nd (OH) 3. 3H20), Neodymium nitrate (preferably the commercially available compound with the formula Nd (N03) 3.6H20), Neodymium oxalate (preferably the commercially available compound with the formula Nd2 ( (COO) 2) 3. 1 OH20), Neodymium sulfate (preferably the commercially available compound with the formula Nd2 (S04) 3. 8H20), Yttrium Acetate (preferably the commercially available compound with the formula Y (CH3CO0) 3.4H20), Yttrium
carbonate (preferably the commercially available compound with the formula Y2 (C03) 3. 3H20), Yttrium nitrate (preferably the commercially available compound with the formula Y (N03). 3H20), Yttrium oxalate (preferably the commercially available compound with the formula Y2 ( (COO) 2) 3. 1OH20), Yttrium oxide (preferably the commercially available compound with the formula Y203), Yttrium sulphate (preferably the commercially available compound with the formula Y2 (SO4) 3. 6H20), Lanthanum acetate (preferably the commercially available compound with the formula La (CH3CO0) 3.3H20), Lanthanum carbonate (preferably the commercially available compound with the formula La2 (C03). 3H20), Lanthanum nitrate (preferably the commercially available compound with the formula La (N03) 3.6H20), Lanthanum oxalate (preferably the commercially available compound with the formula La2 ( (COO) 2) 3. 9H20), Lanthanum oxide (preferably the commercially available compound with the formula La203), Cerium acetate (preferably the commercially available compound with the formula Ce (CH3CO0) 3. xH20), Cerium ammonium nitrate (preferably the commercially available compound with the formula (NH4) 2Ce (NO3) 6), Cerium ammonium sulfate (preferably the commercially available compound with the formula Ce (NH4) 4. (SO4) 4. xH20), Cerium carbonate (preferably the commercially available compound with the formula Ce2 (CO3) 3. xH20), Cerium hydroxide (preferably the commercially available compound with the formula Ce (OH) 4. H20), Cerium nitrate (preferably the commercially available compound with the formula Ce (N03) 3. xH20), Cerium oxide (preferably the commercially available compound with the formula Ce02), Cerium oxalate (preferably the commercially available compound with the formula Ce2 ( (COO) 2) 3.9H20), Cerium sulphate (preferably the commercially available compound with the formula Ce (S04) 2. xH20), Praseodymium acetate (preferably the commercially available compound with the formula Pr (CH3CO0) 3. xH20), Praseodymium carbonate (preferably the commercially available compound with the formula Pr (C03) 3. xH20), Praseodymium nitrate (preferably the commercially available compound with the formula Pr (N03) 3. xH20), Praseodymium oxalate (preferably the commercially available compound with the formula Pr2 ( (COO) 2) 3. xH20), Praseodymium oxide (preferably the commercially available compound with the formula Pur6011), Praseodymium sulphate (preferably the commercially available compound with the formula Pr2 (SO4) 3. 8H20), Samarium acetate (preferably the
commercially available compound with the formula Sm (CH3CO0) 3. xH20), Samarium carbonate (preferably the commercially available compound with the formula Sm2 (CO2) 3. xH20), Samarium oxalate (preferably the commercially available compound with the formula Sm ( (COO) 2) 3. 9H20), Samarium oxide (preferably the commercially available compound with the formula Sm203), Samarium sulphate (preferably the commercially available compound with the formula Sm2 (SO4) 3.8H20), Europium acetate (preferably the commercially available compound with the formula Eu (CH3C00) 3. xH20), Europium carbonate (preferably the commercially available compound with the formula Eu2 (CO3) 3. xH20), Europium nitrate (preferably the commercially available compound with the formula Eu (N03) 3.6H20), Europium oxalate (preferably the commercially available compound with the formula Eu2 ( (COO) 2) 3. xH20), Europium oxide (preferably the commercially available compound with the formula Eu203), Europium sulphate (preferably the commercially available compound with the formula Eu2 (S04) 3. 8H20), Gadolinium acetate (preferably the commercially available compound with the formula Gd (CH3CO0) 3. 4H20), Gadolinium carbonate (preferably the commercially available compound with the formula Gd2 (C03) 3. xH20), Gadolinium oxalate (preferably the commercially available compound with the formula Gd ( (COO) 2) 3. 1OH20), Gadolinium nitrate (preferably the commercially available compound with the formula Gd (N03) 3. H20), Gadolinium oxide (preferably the commercially available compound with the formula Gd203), Terbium acetate (preferably the commercially available compound with the formula Tb (CH3CO0) 3. xH20), Terbium carbonate (preferably the commercially available compound with the formula Tb2 (CO3) 3. xH20), Terbium nitrate (preferably the commercially available compound with the formula Tb (N03) 3. xH20), Terbium oxalate (preferably the commercially available compound with the formula Tb2 ( (COO) 2) 3. 1OH20), Terbium sulphate (preferably the commercially available compound with the formula Tb2 (SO4) 3. 8H20), Terbium oxide (preferably the commercially available compound of formula Tb407), Dysprosium acetate (preferably the commercially available compound with the formula Dy2 (CH3CO0) 3. xH20), Dysprosium carbonate (preferably the commercially available compound with the formula Dy2 (CO3) 3. xH20), Dysprosium oxalate (preferably the commercially available compound with the formula Dy2 ( (COO) 2) 3. 1OH20), Dysprosium oxide (preferably the commercially available
compound with the formula Dy203), Dysprosium sulphate (preferably the commercially available compound with the formula Dy2 (SO4) 3.6H20), Holmium acetate (preferably the commercially available compound with the formula Ho (CH3CO0) 3. xH20), Holmium carbonate (preferably the commercially available compound with the formula Ho2 (CO3) 3. xH20), Holmium oxalate (preferably the commercially available compound with the formula Ho2 ( (COO) 2) 3. 6H20), Holmium oxide (preferably the commercially available compound with the formula Ho203), Holmium sulphate (preferably the commercially available compound with the formula Ho2 (SO4) 3.6H20), Erbium acetate (preferably the commercially available compound with the formula Er (CH3CO0) 3. xH20), Erbium nitrate (preferably the commercially available compound with the formula Er (N03) 3. 5H20), Erbium oxide (preferably the commercially available compound with the formula Er203), Erbium sulphate (preferably the commercially available compound with the formula Er2 (SO4) 3. 8H20), Thulium acetate (preferably the commercially available compound with the formula Tm (CH3CO0) 3. xH20), Thulium carbonate (preferably the commercially available compound with the formula Tm2 (CO3) 3. H20), Thulium nitrate (preferably the commercially available compound with the formula Tm (N03) 3. xH20), Thulium oxalate (preferably the commercially available compound with the formula Tm2 ( (COO) 2) 3. 6H20), Thulium oxide (preferably the commercially available compound with the formula Tm203), Ytterbium acetate (preferably the commercially available compound with the formula Yb (CH3CO0) 3. 4H20), Ytterbium carbonate (preferably the commercially available compound with the formula Yb2 (CO3) 3. xH20), Ytterbium nitrate (preferably the commercially available compound with the formula Yb (NO3) 3. xH20), Ytterbium oxalate (preferably the commercially available compound with the formula Yb2 ( (COO) 2) 3. 1OH20), Ytterbium oxide (preferably the commercially available compound with the formula Yb203), Ytterbium sulphate (preferably the commercially available compound with the formula Yb2 (SO4) 3. 6H20), Lutetium acetate (preferably the commercially available compound with the formula Lu (CH3CO0) 3. xH20), Lutetium nitrate (preferably the commercially available compound with the formula Lu (N03) 3. H20), Lutetium oxide (preferably the commercially available compound with the formula Lu203), Lutetium sulphate (preferably the commercially available compound with the formula Lu2 (S04) 4. 8H20), and Scandium oxide (preferably the commercially available
compound with the formula Sc203) ; Rare-earth mixed metals include ; Yttrium-Aluminium Alloy (Y-Al), Cerium Mishmetal, Neodymium Allows (for instance Nd-Dy, Nd-Fe, Nd-Fe-Dy, Nd-Fe-B), Samarium Alloy (for instance, SmCo), Dysprosium Alloy (for instance DyFe and DyCo), and Scandium-Aluminium Alloy (Sc-Al); Rare-earth borides include: Lanthanum boride (LaB6) ; Rare-earth sulfides include; Cerium Sulfide (Ce2S3); Rare-earth halides include: Neodymium chloride (preferably the commercially available compound with the formula NdCl3. 6H20), Neodymium fluoride (NdF3), Yttrium chloride (preferably the commercially available compound with the formula YC13. 6H20), Yttrium fluoride (YF3), Lanthanum chloride (preferably the commercially available compound with the formula Lacs3. xH20), Lanthanum fluoride (LaF3), Cerium chloride (preferably the commercially available compound with the formula CeCl3. xH20), Cerium fluoride (CeF3), Praseodymium chloride (preferably the commercially available compound with the formula PrCl3. xH20), Praseodymium fluoride (PrF3), Samarium chloride (preferably the commercially available compound with the formula SmCl3. H20), Samarium fluoride (SmF3), Europium chloride (preferably the commercially available compound with the formula EuC13. 6H20), Europium fluoride (EuF3), Gadolinium chloride (preferably the commercially available compound with the formula GdCl3. 6H20), Gadolinium fluoride (GdF3), Terbium chloride (preferably the commercially available compound with the formula TbCl3. 6H20), Terbium fluoride (TbF3), Dysprosium chloride (preferably the commercially available compound with the formula DyCl3. 6H20), Dysprosium fluoride (DyF3), Holmium chloride (preferably the commercially available compound with the formula HoCl3. 6H20), Holmium fluoride (DyF3), Erbium chloride (preferably the commercially available compound with the formula ErC13. 6H20), Erbium fluoride (ErF3), Thulium chloride (preferably the commercially available compound with the formula TmCl3. 7H20), Thulium fluoride (TmF3), Ytterbium chloride (preferably the commercially available compound with the formula YbCl3. 6H20), Ytterbium fluoride (YbF3), Lutetium chloride
(preferably the commercially available compound with the formula LuCl3. 6H20), Lutetium fluoride (LuF3), and Scandium fluoride (ScF3).
More preferably the tagging component is an inert rare-earth oxide and even more preferably selected from the oxides with the chemical formulae; Sc203, Y203, La203, Ce02, Pr6011, Nd203, Sm203, Eu203, Gd203, Tb407, Dy203, H0203, Er203, Tm203, Yb203, Lu203. These oxides are preferred due to their high melting points (thermal stability), melting between-2200-2490°C as well as their general resistance to chemical attack at the temperatures required to manufacture and process polymeric materials. The most preferred of these oxides are those which are white in appearance and therefore not prone to discolour the polymer material. Included in this most preferred category are Y203, La203, Eu203, Gd203, Dy203, Ho203, Yb203 and Lu203. In another embodiment of the present invention it is preferred to use mixtures of the aforementioned inert rare-earth compounds.
In order for the rare-earth compounds of the present invention to act as effective tracers or "tags"they should be present in detectable amounts. Accordingly, the tagging component of the present invention is typically present in the polymeric material in an amount of from about 0.0001 to about 2.0% by weight of the total polymeric material. More preferably the total amount of the tagging component in the polymeric material is from 0.0001 to 1.0%, and most preferably from 0.001 to 0.1% by weight of the total polymeric material. The tagging component of the present invention can be present in the polymeric material as a single inert rare earth compound or a mixture of two or more inert rare-earth compounds. The present invention also encompasses polymeric materials which are tagged by way of one or more inert rare-earth compounds and one or more of the tagging components which may be, for instance, the fluorophores disclosed in US 5,461, 136 or US 6,514, 617. When the tagged polymeric material of the present invention includes a mixture of two inert rare- earth compounds the preferred mixture ratios are 1: 0.1 to 1: 10, with a more preferred ratio of 1: 0.1 to 1: 3. Varying the quantity and nature of the inert rare-earth tags of the present invention advantageously allows not only for identification of the source of a particular material, but may also serve to identify specific batches of manufactured polymeric
material from the same manufacturer. This enables effective identification for the quality control of each batch of the polyrneric material produced.
A further advantage of the preferred inert rare-earth tagging compounds of the present invention is that they are generally characterised by sharp absorption bands in the visible, ultraviolet and near infrared. Such electronic transitions make such rare-earth compounds (especially rare-earth oxides) easy to detect and quantify and thus make them suitable candidates as tags. Accordingly, these characteristic electronic transitions of the rare-earth compounds allows for the polymeric materials to be distinguished easily from other raw materials which do not have the same electronic transitions. Furthermore, as rare-earth compounds are rarely ever present in the raw materials which are used to prepare the polymeric materials, such compounds would be easily identifiable without interference from other components in the polymeric material. This also allows for accurate quantification of the rare-earth compound which has been incorporated into the polymeric material.
The detection of the inert rare-earth tagging compounds of the present invention can be performed using conventional analytical methods including Atomic Absorption Spectroscopy, Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), ICP-mass spectroscopy (ICPMS), X-Ray Fluorescence Spectroscopy (XRF), or Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDXA). The advantage of ICPMS in detecting rare earth elements was reported by Jarvis, K. E. , (1989), Elemental Analysis of the Lanthanides, pages 65-92, in J. C. G Lunzli and G. R. Choppin (ed) Lanthanide Probes in life, chemical and earth sciences ; Elsevier Science, Amsterdam, The Netherlands. In this report Jarvis commented on the exceptional detection limits for all rare earth elements (including rare earth oxides), in a range from nanograms per kilogram to micrograms per kilogram. The preferred method of detecting quantifiable amounts of an inert rare-earth tagging component of the present invention is through the use of ICP-OES mainly due to the lower cost associated with running large numbers of samples. In a typical analytical procedure using ICP-OES, the dissolved and tagged polymeric material is sprayed as an aerosol into an argon plasma. At temperatures of
around 6500K the elements are atomised and/or ionised. The temperatures used are high enough to excite atoms and ions electronically so that they emit light. The resulting spectrum consisting of many different emission lines can be analysed to determine which elements are present and can serve as an indication of the quantities of different elements present. As such, it is preferred that in addition to identifying the presence of the tagging component the detector is capable of quantitatively determining the amount of the tagging component incorporated into said polymeric material and/or the ratio of one inert rare- earth compound to another in the tagging component.
Accordingly, the present invention also provides a tagging system for a polymeric material including: a tagging component which is incorporated into the polymeric material and comprises an inert rare-earth compound or mixture of inert rare-earth compounds ; and a detector to identify the presence of said tagging component in said polymeric material.
The tagging component of the present invention can be incorporated into the polymeric material either during the polymer manufacturing process, during the processing of such polymeric materials to produce the processed articles, or a combination thereof. The tagged component is are preferably incorporated into the polymeric material such that it is dispersed uniformly throughout the polymeric material or such that it is dispersed on a portion of the polymeric material. By way of example and with respect to the processing of thermoplastic polymeric materials, the polymeric material (which includes additives commonly employed, for example catalysts, pigments, stabilizers, lubricants, etc. ), can be premixed with the tagging component. This can be carried out either in, for example, powder, pellet, and/or liquid form, and then fed from a hopper into the extruder. The extruder is generally maintained at a sufficiently high temperature to melt the polymer precursor without causing decomposition thereof. Optionally the tagging component may be added in the feed throat or through an alternate injection port of an injection molding machine or other type of molding. It will be appreciated that either processing method entails the use of elevated temperatures. As mentioned previously one of the advantages of the present invention is that the inert rare earth tagging component of the present invention
is generally thermally stable and accordingly unlikely to decompose or degrade at the temperatures required for the manufacture or processing of the polymeric materials.
As noted in the aforementioned list of preferred commercial compounds, many of these compounds are available as hydrates ("x"denoting that the degree of hydration of the commercial product is unknown or variable). It will be recognised that when incorporating any of these compounds as the tagging component according to the present invention into the polymeric material, the degree of hydration may vary. This does not effect the tagging capability of the component as the rare-earth content should not change.
In one preferred embodiment the polymeric material is a powder coating composition which has been tagged according to the present invention. Powder coating is a well established process which basically comprises the application of a polymer-based fusible coating powder composition to a substrate, heating the powder on the substrate causing the powder to melt and reflow, and cooling the resultant melt to form a solid coating on the substrate ("curing"). The terms"coating powder"and"powder coating"are sometimes used interchangeably in the art. However, in order to avoid confusion the term"coating powder"as used herein refers to the powder material and the term"powder coating"refers to the application and curing process and the film once applied to the substrate and cured.
Powder coating offers the advantage of high coating efficiency, satisfies a multitude of functions, and emits little or no volatile organic compounds (VOC). In this manner, coating powders can be applied to a variety of substrates including wood, metal, glass and even some plastics. Depending on the specific chemical make-up of the coating powder, powder coating can enhance the aesthetics of the substrate and/or provide added protection to the substrate. In particular, substrates may be powder coated in order to enhance electrical insulation properties, mechanical and chemical resistance and/or to avoid corrosion and weathering. For instance, thin film epoxy powder coats produce high attractive coatings of various gloss or surface textures while also providing toughness and corrosion resistance. Accordingly, coating powder compositions to be used in powder coating are frequently separated into decorative and functional grades depending upon
their specified purpose.
Coating powder compositions are generally based on either thermoplastic or thermosetting polymers. There are also many other components which may be added in addition to these polymers in the preparation of coating powder compositions and these additives generally assist with curing or provide the composition with specific properties. The tagging components of the present invention can serve as either a tag for the manufactured polymers which are used in coating powder compositions or of the coating powder composition itself.
Once a coating powder has been applied to a substrate and cured it can be very difficult to readily determine the origin of the coating powder. This is due to the fact that coating compositions prepared by different companies share many of the same components, and that the crosslinking which occurs during curing makes it difficult to identify and quantify the amounts and ratio of the compounds of the original coating powder which may assist in determining the origin of the powder coating. Determining the origin of a coating powder composition can be important should a powder coating become defective. The ability to accurately and readily identify the origin of a powder coating would be of great assistance in resolving warranty claims and preventing the substitution of low grade or poor quality coating powder composition for quality products. Determination of the origin of a coating powder composition (or powder coat) is particularly important in the resolution of customer complaints where multiple powder coatings may have been used on a single job and to ensure that the correct coating powder composition has been used as specified on large building projects.
The coating powder compositions incorporating the inert rare-earth tagging compound (s) of the present invention may be prepared by conventional methods including melt-mixing or dry-blend processes.
In a melt-mixing process the dry ingredients of the composition are generally weighed into a batch mixer, preferably a high speed impeller mixer such as a Henschel, Wellex or
Littleford mixer. These mixers impart high shear and accordingly mixing times are generally in the order of 2-10 minutes.
After the initial mixing the composition can be melt-compounded in a high-shear mixer.
This facilitates thorough dispersion of the individual components of the composition in the molten resin of the melt. Generally residence times within the high-shear mixer is a few minutes, which is usually adequate for compounding compositions based on thermosetting materials like epoxy, polyester, polyurethane, fluorocarbon, acrylic, and epoxy/polyester hybrid based polymer compositions.
Thermoplastics like PVC, polyamide, polyethylene, polypropylene, fluorocarbon, polyester and cellulose ester based compositions, are usually compounded on an extruder.
The strands of molten resin or extrudate produced in the extruder are immediately water cooled and pelletized before being ground.
Thermosetting polymer based compositions are also generally cooled quickly after being extruded to prevent reaction between resin and curing agent. The cooled strands from the extruder are usually broken into small chips suitable for fine grinding.
Thermoplastic polymer based compositions are usually ground on hammer or pin mills after cryogenic freezing with liquid nitrogen. Such a process is not usually required for thermosetting polymer based compositions as they are usually brittle enough to allow for efficient grinding.
An air-classifying mill is generally used to produce coating powder compositions from these resin compositions with particle-size ranges suitable for both fluidized bed and electrostatic powder coating applications.
After achieving the desired particle size distribution the coating powder compositions are generally packaged ready for distribution. However, coating powder compositions which contain functional additives like colloidal silica or other high oil absorption pigments can
be blended with the coating powder compositions post-grinding.
Dry-blending techniques are preferred for preparing PVC based coating powders for fluidized-bed coating applications. The process is less complicated than the melt-mixing process and simply entails loading the dry components of the composition into a high intensity mixer. After mixing is commenced and the temperature begins to rise, plasticizers and other liquid additives can be added. Mixing is continued until the resin absorbs the liquid additives and the composition becomes a free-flowing powder.
Generally the mixing is continued until the temperature reaches 110°-130°C and the resultant powder composition is transferred to a cooling mixer. At this stage, dispersion grade PVC resin is added once the temperature of the powder is cooled to below 37°C.
After mixing again, the composition is screened to remove agglomerates. The resultant coating powder composition can then be packaged for distribution. Polyamide based coating powders can also be prepared by such dry-blending techniques.
To prepare coating powder compositions incorporating a tagging component according to the present invention, one can add the component at any stage during the aforementioned processing. Thus, the tagging component can be added with the dry ingredients into the batch mixer, or prior to being melt-compounded. It is also possible to add the tagging component prior to grinding or even after grinding when blending is conducted to disperse any additional additives post-grinding. The tagging component of the present invention can also be added in a post blend way (during or after the milling stage) and still achieve acceptable incorporation of the tagging component in the coating powder.
Preferably, the tagged coating composition is produced in the form of particles of polymer powder each containing the tagging component. That is, the composition consists of a uniformly distributed mixture of the tagging component and polymer powder. In this embodiment the tagging component is introduced in the manufacturing process as one or more pre-mixed intermediates. That is, prior to mixing the tagging component to the bulk polymer composition the tagging component is mixed with a portion of the precursors to the polymer powder. This ensures that the intermediate mixture consists of a uniformly
distributed mixture of the tagging component and polymer composition. This can be done, for instance, with a tumble mixing or a ribbon blender process. After uniformity has been achieved the intermediate mixture can be added to the remaining quantity of the polymer composition and mixed further. The bulk mixture can then be subjected to the aforementioned processes for preparing coating powders.
After application of the coating powder to the substrate, identification of the tagged component can be achieved by taking a scraping from the substrate of a portion of the powder coat. The scraped off portion of the powder coat can be analysed for rare-earth elements using the analytical techniques mentioned previously. Preferably the rare-earth element content is analyzed by ICP-OES. To effect analysis by this method it is preferred that the scraped off portion of the powder coat is dissolved in an acid solution. Preferred solutions include sulphuric and nitric acid. More preferably the acid solution is a 50: 50 mixture of concentrated sulphuric and nitric acid.
In another preferred embodiment the polymeric material which has been tagged according to the present invention are composite wood panels, including particle board, medium density fibreboard (MDF), oriented strand board (OSB), plywood and combinations thereof.
The cellulose-based particles selected for use in the manufacture of composite panels will be dependent upon the nature of the composite panels to be produced. For instance, particle board may be made from small discreet particles of wood. The wood particles may be made by cutting or breaking of the wood, their shape not being narrowly critical to the construction of the particle board. The particles of wood generally contain a moisture content of from 2 to 10% by weight. The manufacture of particle board generally combines a mechanical mixing of the particles and a binder composition (including a polymer resin) followed by the application of heat and pressure so as to cure the resin and form the particle board. Typically the curing temperatures are in the range of from 130°C to 240°C although, dependent on the formulation other temperatures may be possible.
Generally particle boards contain from 3 to 40% by weight of resin, preferably from 5 to 20% by weight of resin.
Medium density fibreboard comprises cellulose-based fibres which are in the form of a wood pulp. The binder is added to the wood pulp and the mixture dried to form a mat of dried fibres and binder. The temperatures chosen for the drying of the mixture are preferably such that the mixture is dried whilst the binder is not subject to conditions which will induce substantial curing. The dried mat is consolidated into the desired preform which is subsequently subjected to heat and pressure so as to cure the binder and produce the desired composite board. The cellulose fibre may be dried at temperatures ranging from 80°C to 140°C.
The binder composition for these composite wood panels typically comprise a formaldehyde-based polymer resin. Formaldehyde-based resins incorporate formaldehyde along with a comonomer or comonomers.
Suitable comonomers for use in the formaldehyde-based resin include polyfunctional amines, phenols, and other comonomers capable of forming copolymers with the formaldehyde.
The polyfunctional amines comprise two or more primary, secondary and or tertiary amine groups. Examples of suitable polyfunctional amines include melamine, urea, guanidines, para-toluene sulfonamide, triazines, thiourea and dicyandiamide. Preferred polyfunctional amines include melamine and urea. Preferably the polyfunctional amine is urea.
Examples of suitable phenols include phenol, resorcinol, tannins, lignins, bisphenol A, cresol and xylenol.
Preferably, the formaldehyde-based resin may be selected from the group consisting of urea formaldehyde resins (UF), phenol formaldehyde resins (PF), phenol urea formaldehyde resins, melamine urea formaldehyde resins, phenol melamine urea formaldehyde resins, phenol melamine formaldehyde resins.
In urea formaldehyde resins it is preferable that the molar ratio of formaldehyde to comonomer is in the range of from about 0.3 : 1 to about 1.5 : 1, more preferably from about 0.4 : 1 to about 1.1 : 1, even more preferably about 0.4 : 1 to about 0. 9 : 1, and most preferably about 0.45 to about 0.75.
In urea formaldehyde resins part of the urea may be replaced with melamine. The modification of urea formaldehyde resins with melamine may provide improved water resistance to the binder composition, as well as the composite panels resulting in improved dimensional stability.
The melamine may replace up to 85% by weight of comonomer. The urea formaldehyde resin modified with melamine may include a melamine component of from about 0.5 to about 60% and preferably from 1 to 50% weight on solids.
Urea formaldehyde resins are preferably formulated to a viscosity of up to about 700 cps and more preferably in the range of about 30 to 600 cps. Preferably, when it is desired to use the urea formaldehyde resins in applications where the stability of the unpressed composite is an important factor, the viscosity is in range of from about 300 to about 500 cps. It is also possible to use the urea formaldehyde having a viscosity is in the range of from about 30 to about 60 cps.
Preferably, the urea formaldehyde resin comprises from about 40% to about 70% by weight solids, more preferably from about 35% to about 70% by weight solids.
Preferably, the urea formaldehyde resin has a pH in the range of from about 8 to about 10, more preferably from about 8.5 to about 9.5.
In phenol formaldehyde resins it is possible to formulate the resin at either acid curing or alkaline curing conditions. Under acid curing conditions it is preferable to use a high phenol content. Preferably the molar ratio of formaldehyde to comonomer is in the range
of from about 0.4 : 1 to about 1: 1, more preferably from about 0.4 : 1 to about 0.9 : 1, and most preferably about 0.45 : 1 to about 0.7 : 1.
Under alkaline curing conditions it is preferable to use a low phenol content. Preferably the molar ratio of formaldehyde to comonomer is in the range of from about 1. 8 : 1 to about 4: 1, more preferably from about 2: 1 to about 2.5 : 1, and about 3.5 : 1 to about 3. 8 : 1.
In these phenol formaldehyde resins part of the phenol may be replaced with urea.
The urea may replace up to 50% weight on solids. Preferably the urea may be present in an amount of from about 1% to about 25% weight on solids.
PF resins are preferably formulated to a viscosity of up to about 400 cps and more preferably in the range of about 30 to 400 cps. Preferably, when it is desired to use the phenol formaldehyde resins in applications where the stability of the unpressed composite is an important factor, the viscosity is in range of from about 200 to about 400 cps. It is also possible to use the phenol formaldehyde resins having a viscosity is in the range of from about 30 to about 60 cps.
Preferably, the phenol formaldehyde resin comprises from about 30% to about 50% by weight solids, more preferably from about 35% to about 45% by weight solids.
Preferably, the phenol formaldehyde resin has a pH in the range of from about 7 to about 12, more preferably from about 9 to about 12, such as from about 10 to about 12.
A variety of additives such as those used in the manufacture of conventional formaldehyde resins may incorporated into the formulations of the formaldehyde based resin. pH modifying agents such as acids, bases and buffers. Acids typically used may include formic acid, hydrochloric acid and sulfuric acid. Bases typically used may include sodium hydroxide and potassium hydroxide. Buffers which may be used include triethanolamines
and borax. Other additives include hexamine, which advantageously breaks down to formaldehyde in situ, sulfites, polyvinyl alcohol and sodium metabisulfite.
Isocyanates may also be added to the binder composition to reduce formaldehyde emissions. When using isocyanate based binders, fabricators will generally employ release agents to facilitate removal of the boards from the presses. Generally release agents such as waxes are independently applied to the cellulose fibres. The incorporation of release agents into the formaldehyde-based resin allows greater convenience in the manufacturing process, the fabricator may operate a reduced stock inventory and reduces likelihood of incorrect dosages being used. Alternatively the release agent may be included in the isocyanate component of the system. Suitable release agents include paraffin and synthetic waxes such as montan waxes, polyethylene waxes and polypropylene waxes. Generally the release agent may be present in the formaldehyde based resin in an amount of at least 5% by weight solids of the isocyanate based compound, preferably at an amount of about 10% by weight solids of the isocyanate based compound.
Release agents may preferably be incorporated into the formaldehyde-based resin in the form of an emulsion. An emulsion of the release agent may be formed by emulsifying a blend of the release agent and water in the presence of a surfactant. Preferably the blend is heated to an elevated temperature which promotes the formation of the emulsion. Suitable surfactants for promoting the formation and stabilisation of the emulsion include ethylene oxide derivatives.
Alternatively, the release agent may be incorporated in an unemulsified form. This advantageously enables the release agent to be incorporated without the need for additional surfactant.
The release agents may preferably be incorporated into the formaldehyde resin in the final stages of manufacture or may be incorporated by blending with the formaldehyde resin after the manufacture of the formaldehyde resin has been completed. Typically, the release
agent may be added as an emulsion. Alternatively the release agent may be added in solid form.
When tagging the composite wood panel according to this embodiment it is preferred that the tag is added into the binder composition. For instance, the cellulose-based particles may be blended with the formaldehyde-based resin, either where the formaldehyde based resin is premixed with the tagging component or where the component is simply added simultaneously. Preferably this is done when the other additives are included during the manufacture of the formaldehyde based resin. This is best done during the resin cool down stage, where stirring ensures uniformity. Alternatively one or more components which make up the binder composition may include the tagging components and the binder composition may be pre-blended with the cellulose-based particles and the remaining components subsequently combined with the pre-blended materials. For example, the cellulose-based particles may be blended with the formaldehyde-based resin and subsequently the tagging component may be incorporated into the pre-blended composition. Alternatively, a formaldehyde-based resin and the tagging component may be blended with the cellulose particles and subsequently further comonomer may be added to the pre-blended components to decrease the molar ratio of formaldehyde to comonomer.
Identification of the tagging component of the present invention can be achieved by taking a portion of the panel which can then be analysed for rare-earth elements using the analytical techniques mentioned previously. Preferably the rare-earth element content is analysed by ICP-OES. To effect analysis by this method it is preferred that the removed portion of the panel is dissolved (completely or partially) in an acid solution. Preferred solutions include sulphuric and nitric acid. More preferably the acid solution is a 50: 50 mixture of concentrated sulphuric and nitric acid.
The invention will now be described with reference to the following examples which are intended only for the purpose of illustrating certain embodiments of the invention and are not to be taken as limiting the generality of the invention previously described.
Examples Example 1 An intermediate mixture was prepared by mixing uniformly a combination of benzoin 35%, flow additive 64% and 1% w/w iron oxide. The intermediate mixture (1.5%) was then added to polyester resin 63%, crosslinker 3.3%, pigment 32.2%. The mixture was agitated to ensure uniformity and then extruded, cooled and granulated and then milled to form a coating powder. The coating powder was then applied electrostatically (using a Gem PG-1 Powder coating cup gun at a voltage of 80kV) to an aluminium substrate and baked at 200°C for 10 minutes in an electric convention oven.
Example 2 An intermediate mixture comprising a tagged compound was made by mixing uniformly a combination of benzoin 35%, flow additive 62. 8 67% w/w, Yttrium oxide 1.133% w/w and iron oxide 1% w/w. The intermediate mixture (1.5%) was then added to polyester resin 63%, crosslinker 3.3%, pigment 32.2%. The mixture was agitated to ensure uniformity and then extruded, cooled and granulated and then milled to form a coating powder with uniformly distributed tagged compound. The coating powder was then applied electrostatically (using a Gem PG-1 Powder coating cup gun at a voltage of 80kV) to an aluminium substrate and baked at 200°C for 10 minutes in an electric convention oven.
Example 3 An intermediate mixture comprising a tagging compound was made by mixing uniformly a combination of benzoin 35%, flow additive 60. 6 67% w/w, Yttrium oxide 3.333% w/w and iron oxide 1% w/w. The intermediate mixture (1.5%) was then added to polyester resin 63%, crosslinker 3.3%, pigment 32.2%. The mixture was agitated to ensure uniformity and then extruded, cooled and granulated and then milled to form a coating powder with uniformly distributed tagged compound. The coating powder was then applied
electrostatically (using a Gem PG-1 Powder coating cup gun at a voltage of 80kV) to an aluminium substrate and baked at 200°C for 10 minutes in an electric convention oven.
Example 4 An intermediate mixture comprising a tagging compound was made by mixing uniformly a combination of benzoin 35%, flow additive 57.333% w/w, Yttrium oxide 6.667% w/w and iron oxide 1% w/w. The intermediate mixture (1.5%) was then added to polyester resin 63%, crosslinker 3.3%, pigment 32.2%. The mixture was agitated to ensure uniformity and then extruded, cooled and granulated and then milled to form a coating powder with uniformly distributed tagging compound. The coating powder was then applied electrostatically (using a Gem PG-1 Powder coating cup gun at a voltage of 80kV) to an aluminium substrate and baked at 200°C for 10 minutes in an electric convention oven.
Example 5 An intermediate mixture comprising a tagging compound was made by mixing uniformly a combination of benzoin 35%, flow additive 63.277% w/w, Lanthanum oxide 0. 733% w/w and iron oxide 1% w/w. The intermediate mixture (1.5%) was then added to polyester resin 63%, crosslinker 3.3%, pigment 32.2%. The mixture was agitated to ensure uniformity and then extruded, cooled and granulated and then milled to form a coating powder with uniformly distributed tagging compound. The coating powder was then applied electrostatically (using a Gem PG-1 Powder coating cup gun at a voltage of 80kV) to an aluminium substrate and baked at 200°C for 10 minutes in an electric convention oven.
Example 6 An intermediate mixture comprising a tagging compound was made by mixing uniformly a combination of benzoin 35%, flow additive 60.667% w/w, Lanthanum oxide 3. 333% w/w and iron oxide 1% w/w. The intermediate mixture (1.5%) was then added to polyester
resin 63%, crosslinker 3.3%, pigment 32.2%. The mixture was agitated to ensure uniformity and then extruded, cooled and granulated and then milled to form a coating powder with uniformly distributed tagging compound. The coating powder was then applied electrostatically (using a Gem PG-1 Powder coating cup gun at a voltage of 80kV) to an aluminium substrate and baked at 200°C for 10 minutes in an electric convention oven.
Example 7 An intermediate mixture comprising a tagging compound was made by mixing uniformly a combination of benzoin 35%, flow additive 57.333% w/w, Lanthanum oxide 6.667% w/w and iron oxide 1% w/w. The intermediate mixture (1.5%) was then added to polyester resin 63%, crosslinker 3.3%, pigment 32.2%. The mixture was agitated to ensure uniformity and then extruded, cooled and granulated and then milled to form a coating powder with uniformly distributed tagging compound. The coating powder was then applied electrostatically (using a Gem PG-1 Powder coating cup gun at a voltage of 80kV) to an aluminium substrate and baked at 200°C for 10 minutes in an electric convention oven.
Example 8 Film from the powder coating films prepared in examples 1 to 7 was then removed (scraped) from the coated substrate and then tested using ICP-OES. The scraped off paint was dissolved in a solution of a 50: 50 mixture of concentrated sulphuric acid and nitric acid before being analysed. The results are shown below in Table 1.
Table 1 Example Nominal Amount, % w/w Found Amount, % w/w 1 0 Not detected (Y, La) 2 0. 017 Yttrium oxide 0. 01 3 0. 05 Yttrium oxide 0. 03 Example Nominal Amount, % w/w Found Amount, % w/w 4 0. 10 Yttrium oxide 0. 07 5 0. 011 Lanthanum oxide 0. 017 6 0. 05 Lanthanum oxide 0.036 7 0. 1 Lanthanum oxide 0.069
Throughout this specification and the claims which follow, unless the context requires otherwise, the word"comprise", and variations such as"comprises"and"comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.
Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications which fall within the spirit and scope. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any two or more of said steps or features.