Patent Application
20130101837
The invention relates to the field of radiation-curable coatings. More particularly, this invention is related to the field of radiation-curable floor coatings, for instance concrete floor coatings.
Radiation-curable coatings have been applied to surfaces in various industries for decades. Radiation-curable coatings have also been employed, for example, on surfaces such as concrete floors, vinyl, wood, and the like. As the name implies, radiation-curable coatings are cured by exposure to radiation, such as from UV light, visible light, and electron beams.
A subset of radiation-curable coatings is UV-curable coatings. UV-curable coatings are cured by exposure to at least UV radiation; for instance the UV portion of the electromagnetic spectrum, which includes radiation wavelengths of about 100-400 nanometers (nm). Higher wavelengths of radiation may also be included in addition to the UV radiation.
UV-curable coatings comprise components referred to as “photoinitiators” that absorb UV radiation and are thus raised to an excited state. The photoinitiators then either photolyze or degrade into cations or free radicals, which are extremely reactive species. The cations or free radicals react with the oligomers and/or monomers also present in the UV-curable coatings and polymerize to form cured coatings almost instantaneously, such as within seconds.
One benefit of using UV-curable coatings on floor surfaces is the quick speed at which the coatings are cured. Such rapid curing allows for return to normal use of the floor without lengthy delays as required by alternate coatings, such as coatings containing solvents that must evaporate, or coatings that substantially completely cure over a time span of hours to days. Another benefit provided by many UV-curable coatings is their strong mechanical and chemical resistance. For example, certain UV-curable coatings applied to floor surfaces can withstand the weight and friction of a forklift driving on the cured, coated surface within minutes after the UV curing. A further benefit of certain UV-curable coatings is that they comprise 100% solids, and thus do not include volatile organic components in the coating formulations, which allows personnel to work in the area without having significant respiratory health concerns from inhalation of volatile organic components. An additional benefit of UV-curable coatings is that the fact that the polymerization reaction is initiated using UV radiation means that the coating formulation does not have a “pot life”, which refers to the need to use the coating within a certain period of time before it polymerizes in its own container, due to having been mixed with a reactive component. Being a one-component formulation helps eliminate waste from individual projects, as unused coating may be stored for future use.
UV curable concrete coatings are further discussed in the article, “UV Curable Concrete Coatings” by Jo Ann Arceneaux, published in the January/February/March 2009 RADTECH Report; in the article, “Field-Applied, UV-Curable Coatings for Concrete Flooring”, by Peter T. Weissman, published in the January/February/March 2009 RADTECH Report; and in the presentation, “Field Applied UV Coatings for Concrete”, by Peter T. Weissman, presented at the UV/EB East October 2009.
U.S. Patent Publication No. 2002/0164434 discloses a radiation curable floor coating that includes an indicator for determining when curable coatings have cross-linked or cured thereby permitting the applier to know what part of the floor may be used without affecting the surface and what part is still in the curing process. The publication discloses incorporation of a dye or pigment into the liquid materials which dye or pigment is visible to the naked eye when the coating is in the liquid state and significantly less visible after the coating has cured.
A drawback to UV-curable coatings for large surfaces relates to the use of UV radiation sources that are smaller in at least one direction, such as width, than the surface to be cured. For example, typical UV curing instruments are portable machines having a cure width of between about 0.66 meters (26 inches) and about 0.86 meters (34 inches). To cure a large floor surface, then, the machine must be passed over the floor, curing an area of just 0.66-0.86 meters (26-34 inches) wide at a time across the length of the floor, followed by passing over and curing another area, the width of the machine, directly adjacent to the prior area. The one or more lamps, bulbs, and/or light emitting diodes (LEDs) fixed to the UV curing instrument direct emitted UV radiation at the floor surface to cure the coating, such as at a power of between about 4000-20000 watts per meter (100-500 watts per inch). Despite advances to the design of such portable UV radiation sources, there still exists a stray light zone at the edges of the cure unit where low intensity light leakage from the side light shielding of the machine is sufficient to initiate polymerization of coatings at a certain thickness near the surface and partially cure it to a skin layer, but insufficient to drive the polymerization of coatings to the entire thickness and therefore leaving a liquid layer at the bottom of the coating.
Such light leakage adjacent the side edges of the light shield of the UV radiation source typically results in the formation of a wrinkle in the partially cured coating skin layer within seconds of passing the UV curing instrument over the coating. The wrinkle is also referred to as a “buckle”, which exhibits a nonplanar wave pattern that is formed by buckling of the otherwise planar cured portion of the coating located on the top surface of the coating, whereas uncured wet coating remains between the cured portion and the substrate on which the coating was applied. The wrinkle or buckle remains visible at the cured surface, even upon complete curing of the entire thickness by the next curing pass. Each pass down the length of a floor may then be observed as a visible line located at or near the edge of the cured area, which is imparted by the wrinkle or buckle. The area located at or near the edge of the cured area from each curing pass may also be referred to as shoulder area.
A radiation gradient present at the front of a UV radiation source is rarely problematic, because as the UV radiation source proceeds forward, emitted full intensity radiation will quickly drive the polymerization reaction to completion. Similarly, a radiation gradient present at the back of a UV radiation source is not an issue as the coating at which such weak intensity light is directed has already been fully cured.
Typically, wrinkles are not an issue for clear coatings applied at a thickness of less than about 0.15 mm (6 mils), as even stray light can usually cure through the most thickness of coating to certain cure degree, whereas many UV-curable coatings applied at a thickness of about 0.15 mm (6 mils) or more are subject to wrinkling.
The formation of wrinkles has historically been a problem for UV coatings in field applied floor applications, in which the surface to be cured is larger than the UV radiation source, and no effective solution to the wrinkle formation problem has been reported. Indeed, the issue of wrinkle formation is reported in Weissman's UV/EB East 2009 presentation, which discloses on page 15 that wrinkling is “[c]aused by differential cure top to bottom within the film and laterally outside the primary exposure line of sight.” This presentation further states on page 16 that wrinkling is “[p]articularly problematic in colors, matte and high build (>8 mils) coatings.”
Typically, the current approach to minimize the appearance of the wrinkles in the final finish is by reducing the magnitude of the wrinkle of a clear primer or color coat and then to use a thin topcoat to attempt to cover up any visible wrinkles.
It would be advantageous to provide a UV-curable coating formulation that would allow for the application of the coating over an area larger than a UV radiation source, without the formation of wrinkles along or near the edge of each pass of the UV radiation source, in the shoulder areas where weak intensity light from a side edge of the UV radiation source is capable of partially curing only a portion of the coating thickness near the surface. In addition, it would be advantageous to provide a method for coating a surface, for example a concrete floor, with a UV-curable coating that provides a cured surface free of wrinkles formed by partial UV curing from stray light from the UV radiation source.
The invention may be embodied in various exemplary and nonlimiting forms. In particular, this Summary is intended merely to illuminate various embodiments of the invention and does not pose a limitation on the scope of the invention.
In a first embodiment, a radiation-curable coating composition for a floor is provided. The coating composition comprises at least one multifunctional monomer or oligomer, at least one photoinitiator, at least one polymer, and one or more tertiary amine compounds comprising zero or one acrylate crosslinkable double bonds.
In another embodiment, a method for coating a concrete floor is provided. The method comprises applying a coating composition in a predetermined area over a surface of a concrete floor. The coating composition comprises at least one multifunctional monomer or oligomer, at least one photoinitiator, at least one polymer, and one or more tertiary amine compounds comprising zero or one crosslinkable double bonds. Suitable tertiary amine compounds also include the salts of such compounds.
The coating composition comprises a thickness of at least about 0.15 mm on the surface. The method further comprises passing a UV radiation source over a first portion of the predetermined area of the surface to cure the coating composition, wherein a shoulder area of the predetermined area that includes partially cured coating, that is directly adjacent the first portion and that has not had the UV radiation source pass directly over it, has no wrinkles two minutes following the completion of the passing of the UV radiation source over the first portion.
In another embodiment, a coated concrete floor is provided. The coated concrete floor comprises a concrete floor comprising a surface and a radiation-curable coating composition applied directly to the surface, the coating composition comprising at least one multifunctional monomer or oligomer, at least one photoinitiator, at least one polymer, and one or more tertiary amine compounds. The coating composition has a thickness of at least 0.15 mm.
In another embodiment, a coated concrete floor is provided that is coated by the method comprising applying a radiation-curable coating composition in a predetermined area over a surface of a concrete floor, the coating composition comprising at least one multifunctional monomer or oligomer, at least one photoinitiator, at least one polymer, and one or more tertiary amine compounds comprising zero or one crosslinkable double bonds, wherein the cured coating composition comprises a thickness of at least about 0.15 mm; and passing a UV radiation source over a first portion of the predetermined area of the surface to cure the coating composition, wherein a shoulder area of the predetermined area that includes partially cured coating, that is directly adjacent the first portion and that has not had the UV radiation source pass directly over it, has no wrinkles two minutes following the completion of the passing of the UV radiation source over the first portion.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.
a is a photograph of a prior art color coating that has been cured using two passes of a UV radiation source, with a delay of about five seconds between the two passes.
b is a photograph of a prior art color coating that has been cured using two passes of a UV radiation source, with a delay of about thirty seconds between the two passes.
a is a photograph of a prior art color coating applied at a thickness of 4 mils.
b is a photograph of a prior art color coating applied at a thickness of 6 mils.
a is partial diagram of a large surface coated with a radiation-curable coating, over which one pass of a UV radiation source has been made.
b is a partial diagram of the surface of 9a, over which a second pass of a UV radiation source has been made.
The term “wrinkles” is defined to mean a visible wave pattern where the thickness at the valleys of the wave is thinner than the thickness at the flat film area and the thickness at the peaks of the wave is thicker than the thickness at the flat film area. The difference between the thickness at the peak areas and the thickness at the valley areas are at least about 10 μm. The terms “wrinkling”, “buckling” and “zippering” are synonymous and used interchangeably herein, as are the terms “wrinkle”, “buckle” and “zipper”.
The term “flat film area” is defined to mean an area of cured film where the surface of the film is planar.
The term “planar” is defined to mean a surface that generally extends in only one plane and does not include out-of-plane wavelike deformation patterns. A coating that does not comprise wrinkles or buckles is planar, whereas a coating that does comprise wrinkles or buckles is nonplanar.
The term “shoulder area” is defined as comprising a first longitudinal edge located immediately adjacent the area of coating directly over which a UV radiation source has been passed. The shoulder area comprises partially cured coating, which has been subjected to weak intensity UV radiation leaked from the side edge of the UV radiation source. The shoulder area is further defined as comprising a second longitudinal edge located at the boundary of the partially cured coating and the coating that remains uncured.
It is possible that the shoulder area can have coating cured to the bottom, but the coating is only partially cured. The term “partially cured” means that the double bond conversion is low. Therefore, in the shoulder area, it is expected that the coating is partially cured to the bottom, but this partial cure is not to the degree of full cure as in the bulk area. Similarly, the term “partial cure degree” refers to a radiation curable coating that has undergone polymerization; however the double-bond conversion of the polymerization is not complete.
As used herein, the term “about” means±10% of the stated value.
Aspects of the invention are directed to UV-curable coatings for surfaces, such as concrete floors, methods for coating UV-curable coatings onto a surface, and surfaces coated with cured UV-curable coatings.
As noted above, it would be advantageous to provide a UV-curable coating formulation that is capable of allowing the application of the coating at a thickness of at least about 0.15 mm (6 mils) over an area larger than a UV radiation source, without the formation of wrinkles in the shoulder area along or near the edge of each pass of the UV radiation source in the areas where weak intensity light from a side edge of the UV radiation source is capable of partially curing only a portion of the coating thickness near the surface. A shoulder area, as noted above, is the area of coating defined as comprising a first longitudinal edge located immediately adjacent the area of coating directly over which a UV radiation source has been passed. The shoulder area comprises partially cured coating, which has been subjected to weak intensity UV radiation leaked from the side edge of the UV radiation source. The shoulder area is further defined as comprising a second longitudinal edge located at the boundary of the partially cured coating and the coating that remains uncured. The width of any shoulder area would depend on various characteristics of the specific coating and UV radiation source, such as coating thickness, coating composition, and UV radiation intensity.
In some aspects of the instant claimed invention the shoulder area has a width of from about 0.1 cm to about 10 cm. In some aspects the shoulder area has a width of at least about 0.5 cm. In some aspects the shoulder area has a width of from about 0.2 to about 5.0 cm. In an aspect of the invention the shoulder area has a width of approximately about 2.0 cm to about 3.0 cm. In aspects the width of the shoulder area will be controlled in part by the type of UV radiation source used and the method of such use.
In addition, it would be advantageous to provide a method for coating a surface, for example a concrete floor, with a UV-curable coating that provides a cured surface free of wrinkles formed by partial UV curing from stray light from the UV radiation source.
Referring to the drawings, wherein like numbers refer to like elements,
In addition to the term “wrinkling”, the phenomenon of curing of a coating composition at the surface while uncured coating remains underneath has also been referred to as “buckling” or “zippering”, due to the appearance of the partially cured area. The terms “wrinkling”, “buckling” and “zippering” are synonymous and used interchangeably herein, as are the terms “wrinkle”, “buckle” and “zipper”. In general, a wrinkled section 13 comprises a visible pattern of folded, partially cured coating surface segments that are disposed approximately perpendicular to the length of the wrinkled section 13, as shown in
A coating that does not comprise wrinkles or buckles is planar, whereas a coating that does comprise wrinkles or buckles is nonplanar. The magnitude, or height, of each wrinkle or buckle typically increases over time until the partially cured coating composition is subjected to the next pass of UV radiation of sufficient intensity to drive the polymerization reaction to completion, at which time the height of the wrinkles or buckles becomes fixed. Referring to
In contrast,
Moreover, the magnitude of each wrinkle or buckle is typically proportional to the thickness of the applied coating. For instance,
In contrast,
In contrast to
Referring to
An alternate radiation source is a machine comprising light emitting diodes (LEDs). LED radiation sources are disclosed in PCT Patent Application, PCT/US2010/60647, “D1446 BT LED Curing of Radiation Curable Floor Coatings” which claims priority to U.S. Provisional Patent Application No. 61/287,600 filed on Dec. 17, 2009. PCT Patent Application, PCT/US2010/60647 and U.S. Provisional Patent Application No. 61/287,600 are incorporated herein by reference in their entirety.
Radiation intensity can be measured at various locations with respect to a selected radiation source. For example, referring to
It was only at half an inch or more outside of the equipment shield, where the irradiance was below the minimum detectable level of about 5-10 mW/cm2, that partial curing only the skin layer from the stray light occurred. As one of skill in the art will appreciate, the distance longitudinally from the end of a radiation source at which the radiation is sufficiently weak to result in only partial curing the skin layer will depend on characteristics of the particular radiation source, such as the bulb, lamp or LED intensity, equipment shield configuration and location, distance of the radiation source from the coated surface, etc.
In use, a UV radiation source employed to cure a large surface coated with a radiation-curable composition will usually be passed over the surface as depicted in the representations shown in
For instance, if the coated area 90 has a width of 3.05 m (10 feet) and a length of 3.05 m (10 feet), and a UV radiation source has a cure width of 0.86 m (34 inches) and a cure speed of about 105 m (10 feet) per minute, a first spot 93 located at approximately 0.89 m (35 inches) width and 0.15 m (6 inches) length (within the shoulder area 92) on the coated area 90 will become partially cured by the weak intensity stray radiation from the UV radiation source about 3 seconds into the first pass of the UV radiation source over the coated area 90. A second spot 94 located at approximately 0.89 m (35 inches) width and 2.90 m (9 feet 6 inches) length on the coated area 90 (also within the shoulder area 92) will become partially cured by weak intensity stray radiation from the UV radiation source at a time of about 57 seconds. Referring now to
Consequently, the size of a coated surface and the speed at which a UV radiation source is passed over the coated surface will impact the time lapse between a shoulder area being partially cured by weak intensity radiation from a first curing pass and being completely cured by high intensity radiation from a second curing pass. For large surface areas, it is impractical to achieve complete two directly adjacent curing passes of the coating composition on the surface in less than about one minute. As a result, it is an advantage of coating compositions according to the present invention to prevent wrinkling or buckling of the partially cured coating located in the shoulder area adjacent to a main body area that has been fully cured by a first pass of a UV radiation source, for at least about one minute or until a second pass of the UV radiation source can be made to completely cure the shoulder area. In certain embodiments, the inventive coating compositions are free of wrinkles following subjection to weak intensity radiation for at least about 0.5 minutes, or at least about one minute, or at least about two minutes, or at least about five minutes, or at least about ten minutes, or at least about twenty minutes, or at least about thirty minutes, prior to being completely cured by subjection to high intensity radiation from a UV radiation source.
Experiments can be executed to determine the amount of time for wrinkles to form in a shoulder area. Referring again to
Despite various design modifications, it is not believed that there are any available UV radiation sources that provide a radiation cutoff from high intensity light to zero light (e.g., does not provide a leakage of weak radiation at the edges of the shielding of one or more lamps, bulbs, and/or LEDs of the UV radiation source). Aspects of the present invention, however, overcome the problem of wrinkle formation caused by low intensity light leakage by providing specific compositions of UV-curable coating formulations. Accordingly, the particular type or instrument model of the UV radiation source is not a significant factor in achieving wrinkle-free UV-cured coatings according to embodiments of the invention, and any conventional UV radiation source may be employed with aspects of the current invention.
Referring to
Clear coatings can include up to 0.5 weight % of a pigment or dye in the coatings for color tint purposes, and still be considered clear coatings because the coatings do not provide full hiding, i.e., the coatings remain transparent.
As noted above, the present invention provides a solution to the problem of wrinkle formation in clear UV-curable coating compositions such that coatings of up to about 0.64 mm (25 mils), or thicker, may be applied to large areas and cured via UV radiation without the generation of visible wrinkles.
An embodiment of the instant claimed invention is a radiation-curable coating composition for a floor comprising:
at least one multifunctional monomer or oligomer;
at least one photoinitiator;
at least one polymer; and
one or more tertiary amine compounds comprising zero or one acrylate crosslinkable double bonds.
UV-curable compositions according to certain embodiments of the invention comprise at least one monomer in the 100% solids compositions. In certain aspects, the at least one monomer is a reactive diluent monomer. Reactive diluent monomers are well known in the art of radiation curable coatings for optical fiber and many of the reactive diluent monomers that are present in radiation curable coatings for optical fiber are also used in radiation curable coatings for concrete and wood floors. See pages 105 of the article entitled “Optical Fiber Coatings” by Steven R. Schmid and Anthony F. Toussaint, DSM Desotech, Elgin, Ill., Chapter 4 of Specialty Optical Fibers Handbook, edited by Alexis Mendez and T. F. Morse, ©2007 by Elsevier Inc., for a succinct summary of these types of reactive diluent monomers.
In embodiments of the invention, suitable monomers for the UV-curable compositions include for example and without limitation, monomers typically employed in the art of radiation-curable compositions and known by persons skilled in the art. In embodiments of the invention, the one or more monomers are included in an amount of between about 5% and about 90% by weight, or about 10% and about 80%, or about 20% and about 70%, or about 30% and about 60%, or about 40% and about 50% by weight of the total UV-curable composition. In certain aspects of the invention, the monomers comprise a viscosity of equal to or greater than 20 centipoises.
Oligomers suitable for use in the compositions of the instant claimed invention include any oligomer that is already known to be radiation curable. Such oligomers include, but are not limited to: urethane acrylate oligomers, aliphatic urethane acrylate oligomers such as Neorad U-10, available from DSM and aromatic monoacrylate oligomers, such as CN131B, available from Sartomer.
UV-curable compositions according to the invention comprise at least one photoinitiator to initiate the polymerization reaction upon absorption of UV radiation. Photoinitiators and stabilizers are described in the reference text MODERN COATING TECHNOLOGY cited above, on pages 29-34. In general, free radical photoinitiators are well known in the art of radiation curable coatings. See pages 105 of the article entitled “Optical Fiber Coatings” by Steven R. Schmid and Anthony F. Toussaint, DSM Desotech, Elgin, Ill., Chapter 4 of Specialty Optical Fibers Handbook, edited by Alexis Mendez and T. F. Morse, ©2007 by Elsevier Inc., for a succinct summary of these types of photoinitiators.
Typically, free radical photoinitiators are divided into those that form radicals by cleavage, known as “Norrish Type I” and those that form radicals by hydrogen abstraction, known as “Norrish Type II”. As discussed above, tertiary amine compounds have been known to be used as synergists in conjunction with Norrish Type II photoinitiators. Although certain embodiments of the invention comprise Norrish Type II photoinitiators in the UV-curable composition formulation, synergy between a Norrish Type II photoinitiator and a tertiary amine compound is not necessary for the instant invention. Indeed, embodiments of UV-curable coating compositions of the current invention comprise Norrish Type I photoinitiators, which generate free radicals via a fragmentation process (e.g., via cleavage). Any suitable Norrish Type I photoinitiator may be employed, for example and without limitation, a photoinitiator selected from the group consisting of acyl phosphine oxides, benzoin ethers, 2,2-diethoxyacetophenone, benzyl dimethylketal, 1-hydroxycyclohexylphenyl-ketone, 1-hydroxycyclohexyl benzophenone, 2-hydroxy-2-methyl propiophenone, 2-ethoxy-2-isobutoxyacetophenone, 2,2-dimethyl-2-hydroxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2,2-trichloro-4-t-butylacetophenone, 2,2-dimethyl-2-hydroxy-4-t-butylacetophenone, 1-phenyl-1,2-propanedione-2-O-ethoxycarbonyl ester, 1-phenyl-1,2-propanedione-2-O-benzoyl oxime, and combinations thereof. For embodiments comprising Norrish Type II photoinitiators, any suitable Type II photoinitiator as typically known in the art may be employed in the inventive UV-curable compositions. Photoinitiators are included in embodiments of the UV-curable compositions at any suitable amount, for example and without limitation, between about 0.1% and about 5% by weight, between about 1% and about 4% by weight, or about 3% by weight of the total composition.
It was unexpectedly discovered that the addition of polymers to the coating composition assists in preventing, decreasing or delaying the formation of wrinkles. Cured coatings that included polymers exhibited significant wrinkle-resistant properties in terms of wrinkle thickness and/or wrinkle delay time. It also was unexpectedly discovered that increasing the amount of polymer in the coating composition increases the amount of time for wrinkles to form in the coating and may prevent the formation of wrinkles. Examples 1 and 4 show that where the amount of polymer in the coating composition increases, the wrinkle resistant properties of the coating increases.
Suitable polymers for inclusion in radiation-curable compositions according to embodiments of the invention include polymers with no cross-linkable double bonds and polymers comprising crosslinkable double bonds. The preferred polymers are polymers with no cross-linkable double bonds. Suitable polymers include for example and without limitation polyesters, acrylate (co)polymers, methacrylate (co)polymers, cellulose acetate butyrate, vinyl acetate (co)polymers and combinations thereof.
In certain embodiments of the invention non-reactive polymers for inclusion in the compositions have a lower limit of the number average molecular weight, Mn, of 5,000 grams per mol and reactive polymers have a lower limit of the number average molecular weight, Mn, of 10,000 grams per mole. UV-curable compositions according to certain embodiments of the invention comprise non-reactive polymer in the compositions. One or more non-reactive polymers are included in certain embodiments of the invention in an amount of between about 5% and about 60% by weight, or about 10% and about 50%, or about 20% and about 40%, or about 30% by weight of the total UV-curable composition. In addition, in certain embodiments, reactive polymers are included in an amount of between about 5% and about 60% by weight, or about 10% and about 50%, or about 20% and about 40%, or about 30% by weight of the total UV-curable composition.
It was unexpectedly discovered that the addition of tertiary amines assists in preventing, limiting or delaying the formation of wrinkles during curing. Clear coatings with tertiary amines appear continuous across a plurality of portions that were cured in separate passes of the UV radiation source. The amine value of a particular tertiary amine sample is expressed as the number of milligrams of potassium hydroxide equivalent to the amine basicity in 1 g of the sample.
It also was unexpectedly discovered that increasing the amount of tertiary amine in the coating composition increases the wrinkle-resistant characteristics of the composition by increasing the amount of time it takes for a wrinkle to form or preventing wrinkles from forming. As is described below in Examples 1 and 2, increasing the tertiary amine value of a coating composition from 7.5 to 15 milligrams KOH per gram of the total radiation-curable resins in the composition significantly increases the wrinkle-resistant characteristic of the composition. In Example 1 the coating composition with 15 milligrams KOH per gram of the total radiation-curable resins in the composition does not form wrinkles after 10 minutes; in Example 2 the coating composition with 7.5 milligrams KOH per gram of the total radiation-curable resins in the composition exhibits wrinkle formation 5 minutes after the first pass of the UV radiation source.
Tertiary amine compounds have been employed as peroxide scavengers for overcoming oxygen inhibition of polymerization at the coating surface of UV-curable coatings, plus as synergists for Norrish Type II photoinitiators (i.e., photoinitiators that form an active species by a hydrogen abstraction process). However, it is not believed that there has been any investigation into the effects of tertiary amines on polymerization at extremely low radiation intensities such as the stray light condition disclosed in this application. In fact, the amount of radiation provided by light leakage from UV radiation sources is not even above the minimum detectable level of a typical dosimeter, which is about 5-10 mW/cm2. Without wishing to be bound by theory, it is hypothesized that at such low levels of radiation intensity, the small amounts of dissolved oxygen throughout the coating inhibit the photoinitiated polymerization reaction, thus the inclusion of a chain transfer agent, in particular one or more tertiary amine compounds, assists to partially cure enough thickness of the coating from the surface down to prevent wrinkling of this thick skin layer for up to about twenty minutes. In certain aspects, wrinkling is prevented completely regardless of the waiting time.
Suitable tertiary amine compounds include tertiary amine compounds comprising zero or one crosslinkable double bonds, for instance acrylate double bonds, which may also be referred to as “acrylate functionality”. Suitable tertiary amine compounds also include the salts of such compounds. Acrylated amines are commonly preferred over the non acrylated amines due to their advantages of low odor, low extractables, and improved yellowing as compared to the non acrylated amines. When non acrylated amines are employed, it is typically in a low amount, such as less than an amount sufficient to provide an amine value of 7.5 milligrams KOH per gram of the total amount of radiation-curable resins of the radiation-curable composition. Surprisingly, tertiary amine compounds having high acrylate functionality, i.e., comprising two or more crosslinkable double bonds, were not effective at preventing wrinkle formation for about one to about twenty minutes between passes of the UV radiation source. This is unexpected at least because the level of acrylate functionality is not supposed to affect a particular tertiary amine compound's effect on oxygen inhibition during polymerization.
Suitable tertiary amine compounds include some commercially available compounds and mixtures, for example and without limitation CN 386, CN 383 and CN 384, which are each available from Sartomer Company, Inc. (Exton, Pa.), and Ebecryl® P115, available from Cytec Industries Inc. (Woodland Park, N.J.). CN 386, CN 384 and CN 383 are tertiary amines, marketed by Sartomer Company, Inc. as difunctional amine coinitiators for use in conjunction with a photosensitizer such as benzophenone to promote rapid curing under UV radiation. CN383 is a non acrylated amine monomer with zero crosslinkable double bonds. CN384 is an amine acrylate monomer with one crosslinkable double bond. CN386 is a non acrylated amine monomer with zero crosslinkable double bonds. Ebecryl® P115 is a copolymerizable amine marketed by Cytec Industries Inc. as a hydrogen donor, or photoactivator with no acrylate functionality, in UV-curable coatings, optionally in combination with a photosensitizer. Additional suitable tertiary amine compounds for certain embodiments of the invention include for example and without limitation tertiary amine compounds selected from the group consisting of triethylamine, triethanolamine, N,N-dimethyl-p-toluidine, methyl diethanolamine, dimethyl ethanol-amine, 2-n-butoxyethyl-4-dimethylaminobenzoate, 2-ethyl-p-(N,N-dimethylamino) benzoate, 2-ethylhexyl-p-dimethylaminobenzoate.
In embodiments of the invention, one or more tertiary amine compounds are used in amounts sufficient to provide an amine value of at least 7.5 milligrams KOH per gram of the total amount of radiation-curable resins of the radiation-curable composition. In certain aspects, the one or more tertiary amine compounds are included in an amount sufficient to provide an amine value of at least 9 milligrams, or at least 12 milligrams, or at least 15 milligrams, or at least 20 milligrams, or at least 40 milligrams KOH per gram of the total amount of resins of the radiation-curable composition and excludes components such as inorganic fillers. The amount of the one or more tertiary amine compounds will also depend on the rest of the components present in the UV-curable composition.
In embodiments of the invention, the one or more tertiary amine compounds equal at least 5 weight % of the total amount of the radiation-curable composition. In certain aspects, the one or more tertiary amine compounds are included in an amounts equal to at least 10 weight %, at least 13 weight %, at least 15 weight %, or at least 20 weight %, of the total amount of the radiation-curable composition. The tertiary amine compounds, as discussed previously, include the salts thereof.
UV-curable compositions according to certain embodiments of the invention comprise at least one filler component. Suitable fillers include materials that have no significant absorption to visible light radiation (i.e., wavelengths longer than about 400 nm) and at least a portion of UV light radiation (i.e., wavelengths between about 250 nm and about 400 nm). Such suitable fillers according to aspects of the invention are for example and without limitation, fillers selected from the group consisting of any types of silica oxide particles, silicate particles, ceramic particles, clay particles, calcium carbonate particles, aluminum oxide particles, aluminum hydroxide particles, calcium sulfate particles, barium sulfate particles, hollow glass beads, solid glass beads, glass fibers, glass flakes, polymeric particles such as acrylic particles, polyolefin particles, silicon particles and the like, and combinations thereof. For example, ceramic microspheres are commercially available from 3M (St. Paul, Minn.), and Sphericel® hollow glass spheres are commercially available from Potters Industries Inc. (Valley Forge, Pa.). In certain aspects, the average particle size of the fillers comprises 300 microns or less in at least one dimension.
Without wishing to be bound by theory, it is hypothesized that the filler particles scatter weak light present within the coating composition to assist in driving the polymerization reaction to completion. One or more fillers may be present in UV-curable compositions in an amount of between about 1% and about 70% by weight, or between about 5% and about 60%, or between about 10% and about 50%, or between about 15% and about 40%, or between about 20% and about 30%, or between about 10% and about 20% by weight of the total UV-curable composition. In certain embodiments of the present invention, both tertiary amine compounds and fillers are included in UV-curable compositions to provide synergistically enhanced curing of the compositions without the formation of visible wrinkles.
In certain embodiments, the UV-curable composition comprises a topcoat, such as a clear topcoat for concrete. Such topcoats are applied on top of primer coats. Referring to
In certain embodiments, the UV-curable composition comprises a primer coat composition, such as a clear primer coat composition for concrete. Such primer coat compositions are applied directly to clean surfaces to provide good adhesion of the coating to the particular surface, such as concrete. The surface may be cleaned according to methods commonly used in the art of surface coating, wherein the cleaning comprises removing debris and optionally coatings adhered to the surface. In alternate embodiments, the primer coating composition is applied directly to substrates such as wood, vinyl, composite materials, and the like. One advantage of the invention is the ability to apply thick coatings of the UV-curable composition. For instance,
Aspects of the inventive UV-curable compositions allow for a high build clear coating composition to be applied to a surface having a thickness of at least about 0.25 mm (10 mils), or at least about 0.38 mm (14 mils), or at least about 0.46 mm (18 mils), or at least about 0.51 mm (20 mils), or at least about 0.56 mm (22 mils), such as up to about 0.64 mm (25 mils). High build clear coatings on surfaces having an area with at least one dimension greater than the width of a UV radiation source are capable of being cured using UV radiation in more than one pass of the UV radiation source having a time lapse of between about one and about twenty minutes between passes, while remaining wrinkle-fee. For instance, clear primer coat compositions are applied in certain embodiments at a thickness of at least about 6 mils, or at least about 0.30 mm (12 mils), or at least about 0.46 mm (18 mils), or at least about 0.61 mm (24 mils) thick.
In contrast to the inventive coatings, a prior art clear cured coating, having the composition disclosed below in Comparative Example 10, is shown in
According to the invention, a UV-curable coating composition is provided comprising at least one multifunctional monomer or oligomer, at least one photoinitiator, at least one polymer, and one or more tertiary amine compounds, such as in an amount that provides an amine value of at least 7.5 milligrams KOH per gram of the total radiation-curable resins of the radiation-curable composition. In other embodiments, the one or more tertiary amines are provided in an amount comprising an amine value of at least 9 milligrams KOH per gram of the total radiation-curable resins in the coating composition.
In an embodiment of the current invention, a method is provided for coating a concrete floor comprising applying a coating composition over a predetermined area of a surface of a concrete floor, wherein the coating composition comprises at least one multifunctional monomer or oligomer, at least one photoinitiator, at least one polymer, and one or more tertiary amine compounds comprising zero or one crosslinkable double bonds and wherein the coating composition comprises a thickness of at least 0.15 mm (6 mils) on the surface. In other embodiments, the one or more tertiary amines are provided in an amount comprising an amine value of at least 9 milligrams KOH per gram of the total radiation-curable resins in the coating composition. The method further comprises passing a UV radiation source over a first portion of the predetermined area of the surface to cure the coating composition, the first portion comprising a main body area in an initial pass. A shoulder area which is directly adjacent to the main body area does not have the UV radiation source pass over it in the initial pass but is partially cured by the stray light leaked from the edge of the light shield. Then, the UV radiation source is passed over a second portion of the predetermined area of the surface to cure the coating composition, wherein the second portion includes the shoulder area directly adjacent the first portion. The shoulder area in some embodiments has a width of at least about half of a centimeter, at least about one centimeter, at least about 5 centimeters, or at least about 10 centimeters. The passing over the second portion finishes at least about one minute after the passing over the first portion begins; in some embodiments, the passing over the second portion finishes at least about two minutes, or at least about five minutes, or at least about ten minutes, or at least about twenty minutes, or at least about thirty minutes after the passing over the first portion begins. The shoulder area is not visible following the passing of the UV radiation source over the second portion, for example the shoulder area directly adjacent the first portion is planar and/or free of wrinkles and/or buckles following the passing of the UV radiation source over the second portion.
The passing of the UV radiation source according to embodiments of the invention occurs at a rate of between about 4.57 m (15 feet) per minute and about 15.24 in (50 feet) per minute, such as between about 6.10 m (20 feet) per minute and 12.20 m (40 feet) per minute, for instance about 7.62 m (25 feet) per minute. For a coated surface comprising a length of 30.48 m (100 feet), it would take at least about 8 minutes to complete two full passes of the UV radiation source at a pass rate of about 7.62 m (25 feet) per minute, back and forth along the length of the surface, in order to cure two directly adjacent portions of the coated surface. Similarly, for a coated surface comprising a length of 60.10 m (200 feet), it would take at least about 10 minutes to complete two full passes of the radiation source at a pass rate of about 12.20 m (40 feet) per minute, back and forth along the length of the surface, in order to cure two directly adjacent portions of the coated surface. Consequently, the current invention allows surface areas comprising a length of from at least about 12.20 m (40 feet) to about 122 in (400 feet) to be coated to a thickness of at least about 0.15 mm (6 mils) and cured at a UV radiation source pass rate of between about 4.57 m per minute and about 15.24 in per minute (15 and about 50 feet), without forming visible wrinkles in the coating.
In an embodiment of the current invention, a coated concrete floor is provided comprising a surface and a coating composition applied to the surface. The coating composition comprises at least one multifunctional monomer or oligomer, at least one photoinitiator, at least one polymer and one or more tertiary amine compounds comprising zero or one acrylate double bonds, wherein the coating composition has a thickness of at least 0.15 mm (6 mils). In other embodiments, the one or more tertiary amines are provided in an amount comprising an amine value of at least 7.5 milligrams potassium hydroxide KOH per gram of the total UV-curable resins in the coating composition.
In an embodiment of the current invention, a coated concrete floor is provided coated by the method comprising applying a coating composition over a predetermined area of a surface of a concrete floor, the coating composition comprising at least one multifunctional monomer or oligomer, at least one photoinitiator, at least one polymer, and one or more tertiary amine compounds comprising zero or one acrylate double bonds, wherein the cured coating composition comprises a thickness of at least 0.15 mm (6 mils). In other embodiments, the one or more tertiary amines are provided in an amount comprising an amine value of at least 7.5 milligrams KOH per gram of the total UV-curable resins in the coating composition. The method further comprises passing a UV radiation source over a first portion of the predetermined area of the surface to cure the coating composition, the first portion comprising a main body area in a first pass. The UV radiation source does not pass over a shoulder area directly adjacent to the main body area during the first pass but has stray light leaked from the edge of the light shield partially curing the coating at the shoulder area. Then the UV radiation source is passed over a second portion of the predetermined area of the surface to cure the coating composition, the second portion includes the shoulder area directly adjacent the first portion. The passing over the second portion finishes at least about one minute after the passing over the first portion begins, and the shoulder area directly adjacent the first portion is planar and/or free of wrinkles and/or buckles following the passing of the UV radiation source over the second portion.
The following examples are illustrative of embodiments of the present invention, as described above, and are not meant to limit the invention in any way.
A radiation-curable composition comprising a combination of a tertiary amine compound having zero crosslinkable double bonds providing an amine value of 15.0 milligrams KOH per gram of the total radiation-curable resins in the composition, a urethane acrylate oligomer, a polymer, acrylate monomers, and photoinitiators, successfully provides a UV-curable composition that is free of wrinkles upon curing of more than one directly adjacent section of a coated surface. The UV-curable coating comprises the materials provided in Table 1 below. The weight percent of the tertiary amine compounds and the weight percent of polymer in the Examples are provided for comparative purposes.
A UV-curable coating is prepared comprising the materials listed in Table 1, then applied as a primer coat to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, one portion of the 0.25 mm (10 mil) thick coating is cured using a HID Hammerhead UV Floor Curing Equipment model 26-8000A (as shown in
A radiation-curable composition similar to the composition in Example 1, but containing 5 weight percent tertiary amine compound with zero crosslinkable double bonds rather than 10 weight percent of such compound, exhibits wrinkles in the coating within less than ten minutes. The tertiary amine compound provides an amine value of 7.5 mg potassium hydroxide (KOH) per gram of the total radiation-curable resins of the coating composition. The UV-curable coating comprises the materials provided in Table 2 below. A UV-curable coating is prepared comprising the materials listed in Table 2, then applied as a primer coat to a 4 inch×6 inch metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the clear primer coat at the shoulder area starts to show visible wrinkles at 5 minutes.
A radiation-curable composition similar to the composition in Example 1, but containing an acrylated functional acrylic polymer (CN 816) rather than non acrylated acrylic polymer (70%-80%) dissolved in acrylate monomer (20%-30%) exhibits no wrinkles 10 minutes after curing of a first pass, similar to Example 1. The amine acrylate monomer provides an amine value of 15 mg potassium hydroxide (KOH) per gram of the total radiation-curable resins of the coating composition. The UV-curable coating comprises the materials provided in Table 3 below. A UV-curable coating is prepared comprising the materials listed in Table 3, then applied as a primer coat to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the clear primer coat at the shoulder area shows no visible wrinkles for at least about 10 minutes before curing the next pass.
A radiation-curable composition similar to the composition in Example 1, but containing about 5 weight percent acrylic polymer (i.e., 7.1 weight percent acrylic polymer solution in acrylate monomer assuming 70% concentration of polymer), exhibits wrinkles in the coating at a faster rate than the composition in Example 1. The amine acrylate monomer provides an amine value of 19.5 mg potassium hydroxide (KOH) per gram of the total radiation-curable resins of the coating composition. The UV-curable coating comprises the materials provided in Table 4 below. A UV-curable coating is prepared comprising the materials listed in Table 4, then applied as a primer coat to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the clear primer coat at the shoulder area starts to show wrinkles at 6 minutes.
A radiation-curable composition comprising a combination of a tertiary amine compound having one crosslinkable double bond and an amine value of 14.6 milligrams KOH per gram of the total radiation-curable resins in the composition, a urethane acrylate oligomer, a polymer, acrylate monomers, and photoinitiators, successfully provides a UV-curable composition that is free of wrinkles upon curing of more than one directly adjacent section of a coated surface. The UV-curable coating comprises the materials provided in Table 5 below. A UV-curable coating is prepared comprising the materials listed in Table 5, then applied as a primer coating to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the clear primer coat at the shoulder area shows no visible wrinkles for at least about 10 minutes before curing the next pass.
A radiation-curable composition comprising a combination of a tertiary amine compound having zero crosslinkable double bonds and an amine value of 15.1 milligrams KOH per gram of the total radiation-curable resins in the composition, a urethane oligomer, a polymer, acrylate monomers, and photoinitiators, successfully provides a UV-curable composition that is free of wrinkles upon curing of more than one directly adjacent section of a coated surface. The UV-curable coating comprises the materials provided in Table 6 below. A UV-curable coating is prepared comprising the materials listed in Table 6, then applied as a primer coating to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the clear primer coat at the shoulder area shows no visible wrinkles for at least about 10 minutes before curing the next pass.
A radiation-curable composition comprising a combination of a tertiary amine compound having two crosslinkable double bonds and an amine value of 15.1 milligrams KOH per gram of the total radiation-curable resins in the composition, a urethane acrylate oligomer, a polymer, acrylate monomers, and photoinitiators, does not provide a UV-curable composition that is free of wrinkles upon curing of more than one directly adjacent section of a coated surface. The UV-curable coating comprises the materials provided in Table 7 below. A UV-curable coating is prepared comprising the materials listed in Table 7, then applied as a primer coat to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the clear primer coat at the shoulder area shows visible wrinkles within less than about one minute.
A radiation-curable composition comprising a combination of a tertiary amine compound having two crosslinkable double bonds and an amine value of 15.0 milligrams KOH per gram of the total radiation-curable resins in the composition, a urethane acrylate oligomer, a polymer, acrylate monomers, and photoinitiators, does not provide a UV-curable composition that is free of wrinkles upon curing of more than one directly adjacent section of a coated surface. The UV-curable coating comprises the materials provided in Table 8 below. A UV-curable coating is prepared comprising the materials listed in Table 8, then applied as a primer coating to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the cured clear primer coating instantly, or at least within less than about one minute, shows visible wrinkles.
A radiation-curable composition comprising a combination of a tertiary amine compound having four crosslinkable double bonds and an amine value of 15.3 milligrams KOH per gram of the total radiation-curable resins in the composition, a urethane oligomer, a polymer, acrylate monomers, and photoinitiators, does not provide a UV-curable composition that is free of wrinkles upon curing of more than one directly adjacent section of a coated surface. The UV-curable coating comprises the materials provided in Table 9 below. A UV-curable coating is prepared comprising the materials listed in Table 9, then applied as a primer coating to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the cured clear primer coating within about one minute shows visible wrinkles.
A radiation-curable composition comprising a combination of a urethane oligomer, a polymer, acrylate monomers, and photoinitiators does not provide a UV-curable composition that is free of wrinkles upon curing of more than one directly adjacent section of a coated surface. The UV-curable coating comprises the materials provided in Table 10 below. A UV-curable coating is prepared comprising the materials listed in Table 10, then applied as a primer coating to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the cured clear primer coating within about one minute shows visible wrinkles.
A sample starting point clear radiation-curable formulation provided on the Cytec Technical Data Sheet for Ebecryl® 891 does not result in a UV-cured composition that is free of wrinkles upon curing of more than one directly adjacent section of a coated surface. Ebecryl® 891 is a modified polyester acrylate having a theoretical acrylate functionality of 3.6 and a viscosity of 3,000 centipoises (at 25 degrees Celsius). Ebecryl® P115 is a tertiary amine with zero crosslinkable double bonds which provides and an amine value of 12.6 milligrams KOH per gram of the total radiation-curable resins in the composition in Table 11. The UV-curable coating comprises the materials provided in Table 11 below. A UV-curable coating is prepared comprising the materials listed in Table 11, then applied to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the cured clear coating within about one minute shows visible wrinkles.
A radiation-curable composition comprising a combination of a tertiary amine having zero cross-linkable double bonds, acrylate monomers, oligomers, a polymer and a photoinitiator successfully provides a UV-curable composition that is free of wrinkles upon curing of more than one directly adjacent section of a coated surface. The copolymerizable amine provides an amine value of 12.75 mg potassium hydroxide (KOH) per gram of the total radiation-curable resins of the coating composition. The UV-curable coating comprises the materials provided in Table 12 below. A UV-curable coating is prepared comprising the materials listed in Table 12, then applied as a primer coating to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the clear primer coat at the shoulder area shows no visible wrinkles for at least about 10 minutes before curing the next pass.
A radiation-curable composition similar to the composition in Example 12 but with only 5% adipic acid ester polymer provides a UV-curable composition that exhibits wrinkles in the composition more rapidly than the composition in Example 11 The UV-curable coating comprises the materials provided in Table 13 below. A UV-curable coating is prepared comprising the materials listed in Table 13, then applied as a primer coating to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the clear primer coat at the shoulder area shows wrinkles in the shoulder area 4 minutes after curing of the pass.
A radiation-curable composition similar to the composition in Example 12 but with no tertiary amine compound fails to provide a UV-curable composition that is free of wrinkles upon curing of more than one directly adjacent section of a coated surface. The UV-curable coating comprises the materials provided in Table 14 below. A UV-curable coating is prepared comprising the materials listed in Table 14, then applied as a primer coating to a 10.16 cm×15.24 cm (4 inch×6 inch) metal substrate, to a thickness of 0.25 mm (10 mils). Next, the 0.25 mm (10 mil) thick coating is cured according to the method described in Example 1. Following curing of the first pass, observation of the clear primer coat at the shoulder area shows wrinkles 1.5 minutes after curing of the pass.
All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10169997.3 | Jul 2010 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2011/042489 | 6/30/2011 | WO | 00 | 12/31/2012 |
| Number | Date | Country | |
|---|---|---|---|
| 61363118 | Jul 2010 | US |
