Variable chemiluminescent process and product

This invention is directed toward a process for producing chemiluminescent light of varying coloration and to devices which utilize the process. The process incorporates multiple fluorescers, at variable concentrations, having varying degrees of stability in peroxide. At the onset of the reaction, chemiluminescent light is generated by both the peroxide stable and less stable , e.g. peroxide unstable fluorescers, resulting in a first visible color. As the peroxide attacks the unstable fluorescer, its predominant color fades, and a different color is perceived. Inclusion of this process in chemiluminescent light producing devices results in a device which changes colors during its useful life.

FIELD OF THE INVENTION
 This invention relates to chemiluminescent processes and in particular to a
 chemiluminescent product and process which utilizes both peroxide stable
 and peroxide unstable fluorescers; said process and product are capable of
 expressing an initial color upon activation and an alternative color or
 colors as a reaction progresses.
 BACKGROUND OF THE INVENTION
 Chemiluminescence relates to the production of visible light attributable
 to a chemical reaction. The important aqueous chemiluminescence substances
 luminal and lucigenin were discovered in 1928 and 1935, respectively. A
 series of organic soluble chemiluminescent materials were developed in the
 early 1960's based upon a study of the luminescent reactions of a number
 of oxalate compounds. A typical organic system useful for
 chemiluminescence was disclosed by Bollyky et al., U.S. Pat. No. 3,597,362
 and claimed to exhibit a quantum efficiency of about 23% compared with
 about 3% for the best known available aqueous systems.
 In its most basic form the two-component, liquid phase oxalate ester
 chemical light system must comprise an "oxalate component" comprising an
 oxalic acid ester and a solvent, and a "peroxide component" comprising
 hydrogen peroxide and a solvent or mixture of solvents. In addition, an
 efficient fluorescer must be contained in one of the components. An
 efficient catalyst, necessary for maximizing intensity and lifetime
 control, may be contained in one of the components.
 The oxalate component provides an oxalate ester-solvent combination which
 permits suitable ester solubility and storage stability. The peroxide
 component provides a hydrogen peroxide-solvent combination which permits
 suitable hydrogen peroxide solubility and storage stability.
 The solvents for the two components may be different but should be
 miscible. At least one solvent solubilizes the efficient fluorescer and at
 least one solvent solubilizes the efficient catalyst. The fluorescer and
 at least one solvent solubilizes the efficient catalyst. The fluorescer
 and catalyst are normally placed as to permit both solubility and storage
 stability in the final components.
 Typical suitable fluorescent compounds for use in the present invention are
 those which have spectral emission falling between 300 and 1200 nanometers
 and which are at least partially soluble in the diluent employed. Among
 these are the conjugated polycyclic aromatic compounds having at least 3
 fused rings, such as: anthracene, substituted anthracene, benzanthracene,
 phenanthrene, substituted anthracene, benzanthracene, phenanthrene,
 substituted phenanthrene, naphthacene, substituted naphthacene, pentacene,
 substituted pentacene, perylene, substituted perylene, violanthrone,
 substituted violanthrone, and the like. Typical substituents for all of
 these are phenyl, lower alkyl (C.sub.1 -C.sub.6), chloro, bromo, cyano,
 alkoxy (C.sub.1 -C.sub.16), and other like substituents which do not
 interfere with the light-generating reaction contemplated herein.
 The preferred fluorescers are 9,10-bis(phenylethynyl) anthracene,
 1-methoxy-9,10-bis(phenylethynyl)anthracene, perylene, 1,5-dichloro
 9,10-bis(phenylethynyl) anthracene, rubrene, monochloro and dichloro
 substituted 9,10-bis(phenylethynyl) anthracene, 5,12-bis(phenylethynyl)
 tetracene, 9,10-diphenyl anthracene, and 16,17-dihexyloxyviolanthrone.
 The term "peroxide component," as used herein, means a solution of a
 hydrogen peroxide compound, a hydroperoxide compound, or a peroxide
 compound in a suitable diluent.
 The term "hydrogen peroxide compound" includes (1) hydrogen peroxide and
 (2) hydrogen peroxide-producing compounds.
 Hydrogen peroxide is the preferred hydroperoxide and may be employed as a
 solution of hydrogen peroxide in a solvent or as an anhydrous hydrogen
 peroxide compound such as sodium perborate, sodium peroxide, and the like.
 Whenever hydrogen peroxide is contemplated to be employed, any suitable
 compound may be substituted which will produce hydrogen peroxide. The
 hydrogen peroxide concentration in the peroxide component may range from
 about 0.2M to about 15M. Preferably, the concentration ranges from about
 1M to about 2M.
 The lifetime and intensity of the chemiluminescent light emitted can be
 regulated by the use of certain regulators such as:
 (1) by the addition of a catalyst which changes the rate of reaction of
 hydroperoxide. Catalysts which accomplish that objective include those
 described in M. L. Bender, "Chem. Revs.," Vol. 60, p. 53 (1960). Also,
 catalysts which alter the rate of reaction or the rate of
 chemiluminescence include those accelerators of U.S. Pat. No. 3,775,366,
 and decelerators of U.S. Pat. Nos. 3,691,085 and 3,704,231, or
 (2) by the variation of hydroperoxide. Both the type and the concentration
 of hydroperoxide are critical for the purposes of regulation.
 Of the catalysts tried, sodium salicylate and various tetraalkylammonium
 salicylates have been the most widely used. Lithium carboxylic acid salts,
 especially lithium salicylate, lithium 5-t-butyl salicylate and lithium
 2-chlorobenzoate are excellent catalysts for low temperature hydrogen
 peroxide/oxalate ester/fluorescer chemiluminescent systems.
 As outlined above, chemical light is produced by mixing an oxalate ester
 and hydrogen peroxide together in the presence of a catalyst and a
 fluorescer. Typically, fluorescers were chosen that were peroxide stable
 to provide a long lasting glow. In most instances, a single fluorescer has
 been used to produce a particularly colored light. In some cases, two or
 more fluorescers of essentially equivalent stability in peroxide have been
 mixed to produce a blended color. As an example, a blue emitting
 fluorescer will be mixed with a red emitting fluorescer to make a pink
 light.
 Of the numerous fluorescers outlined above, relatively few emit light in
 peroxyoxalate chemiluminescence and are sufficiently peroxide stable (five
 phenylethynyl anthracenes, one violanthrone, and three perylene
 dicarboximides) to yield commercially viable products. While other
 fluorescers are known to emit light they are not peroxide stable, and have
 historically been rejected for commercial use.
 Thus, while chemical lighting devices utilizing such systems have been
 available commercially for more than two decades, the majority of these
 devices have emitted a single color. Exceptions have been two, three, or
 five color devices, e.g. in the form of necklaces, where the multiple
 colors are discrete bands or sections, each formulated to emit a single
 color within the device.
 In every device, however, the color emitted by the device or section of the
 device has been a constant, single color. Green starts and stays green,
 blue starts and stays blue, etc.
 Therefore, the instant invention has perfected a process for producing
 chemical lighting devices which are capable of expressing differently
 colored lights during the course of the ongoing reaction.
 SUMMARY OF THE INVENTION
 The present invention embraces the concept of incorporating multiple
 fluorescers, at varying concentrations, and having varying degrees of
 stability in peroxide, in chemiluminescent reaction mixtures. It has been
 discovered that such mixtures are able to express one particularly colored
 light at the onset of the reaction and express a differently colored light
 as the reaction progresses.
 Oxalate ester chemiluminescent systems contemplated as useful for the
 present invention will ordinarily include an oxalate type ester, a
 peroxide activator, a plurality of fluorescent compounds effective to
 control the frequencies of light emitted over time as a result of the
 reaction between the ester and the peroxide, a catalyst to accelerate the
 reaction and a solvent or mixture of solvents in which the other
 constituents are dissolved or suspended.
 A typical chemical light device in accordance with the present invention is
 formed from the oxalate ester, hydrogen peroxide, catalyst, and a peroxide
 stable fluorescer or fluorescer blend. Examples of peroxide stable
 fluorescers include, but are not limited to:
 9,10-Bis-(Phenylethynyl)Anthracene
 2-Methyl-9,10-Bis-(Phenylethynyl)Anthracene
 1-Chloro-9,10-Bis-(Phenylethynyl)Anthracene
 9,10-Bis-(4-Methoxyphenyl)-2-Chloroanthracene
 9,10-Bis-(4-Ethoxyphenyl)-2-Chloroanthracene
 16,17-Didecycloxyviolanthrone
 LUMOGEN RED.RTM. (a red-emitting perylene dicarboximide fluorescer)
 LUMOGEN YELLOW.RTM. (a yellow emitting perylene dicarboximide fluorescer)
 LUMOGEN ORANGE.RTM. (an orange emitting perylene dicarboximide fluorescer)
 In addition to the normal ingredients, a quantity of a peroxide unstable
 fluorescer is added. Examples of peroxide unstable fluorescers include,
 but are not limited to:
 5,12-Bis-(Phenylethynyl) Napthacene
 5,16,11,12-Tetraphenylnapthacene.
 At the onset of the reaction, the device will luminesce and light will be
 generated by both the peroxide stable and peroxide unstable fluorescers.
 The perceived color being that of the peroxide unstable fluorescer or
 (depending on concentrations) the combination of the stable and unstable
 fluorescers. As the peroxide attacks the unstable fluorescer and it
 suffers degradation, its predominant color fades. The color emitted by the
 stable fluorescer then becomes the only color perceived. The observer thus
 perceives that the device changes from one color to another.
 Accordingly, it is an objective of the instant invention to teach a process
 for producing chemiluminescent light which incorporates a combination of
 peroxide stable and peroxide unstable fluorescers in a single reaction
 mixture.
 It is a further objective of the instant invention to teach a process
 wherein the light generated by the instant process expresses an initial
 visible frequency which yields to one or more alternatively visible
 frequencies as a function of reaction time.
 It is yet another objective of the instant invention to teach a
 chemiluminescent device which functions in accordance with the steps
 taught by the instant process, thereby providing a single device capable
 of expressing multiple colors within the visible spectrum during its
 useful reaction life.
 Other objects and advantages of this invention will become apparent from
 the following description wherein are set forth, by way of illustration
 and example, certain embodiments of this invention.
 DETAILED DESCRIPTION OF THE INVENTION
 A typical chemical light device in accordance with the present invention is
 formed from the oxalate ester, hydrogen peroxide, catalyst, and a peroxide
 stable fluorescer or fluorescer blend. In addition to the normal
 ingredients, a quantity of a peroxide unstable fluorescer is added. Thus,
 a fluorescer component mixture is created which is selected from a first
 group of fluorescer components having a first peroxide stability and a
 second group of fluorescer components having a second peroxide stability,
 the second group being less peroxide stable than the first group. At the
 onset of the reaction, the device will luminesce and light will be
 generated by both the peroxide stable and peroxide unstable fluorescers.
 The perceived color being that of the peroxide unstable fluorescer or
 (depending on concentrations) the combination of the stable and unstable
 fluorescers. As the peroxide attacks the unstable fluorescer and it
 suffers degradation, its predominant color fades. The color emitted by the
 stable fluorescer then becomes the only color perceived. The observer thus
 perceives that the device changes from one color to another. Appropriate
 selection of fluorescers of varying stability will result in the
 production of two or more colors from a discrete mixture of reactants
 during the reaction period.
 This phenomenon is more particularly illustrated by the following examples:

EXAMPLE 1
 A Tri-color Lite-Rope.RTM. Necklace is made with green, red and blue
 sections. The peroxide stable fluorescers
 2-Methyl-9,10-Bis-(Phenylethynyl) Anthracene(Green), LUMOGEN RED (a
 perylene dicarboximide) (Red), and 9,
 10-Bis-(4-Methoxyphenyl)-2-Chloroanthracene (Blue) are used. A peroxide
 unstable fluorescer 5,16,11,12-Tetraphenylnapthacene) is added to each
 colored section. The resulting device glows a bright orange when activated
 by the end user. After 30-40 minutes, the orange color fades and the three
 separate colors of green, red, and blue are revealed.
 The following concentrations of fluorescers are used:

Final
 Section
 Color Stable Fluorescer Unstable Fluorescer
 Green 2-Methyl-9,10-Bis- 5,16,11,12-Tetraphenylnapthacene
 (Phenylethynyl) 0.08% by weight
 Anthracene 0.1% by weight
 Red LUMOGEN RED 0.015% 5,16,11,12-Tetraphenylnapthacene
 by weight 0.06% by weight
 Blue 9,10-Bis-(4-Methoxy- 5,16,11,12-Tetraphenylnapthacene
 phenyl)-2-Chloro- 0.15% by weight
 Anthracene 0.48% by
 weight
 EXAMPLE 2
 A 6" Purple Glow Stick.RTM. Light Stick is made with a combination of
 peroxide stable fluorescers 9,10-Bis-(4-Methoxyphenyl)-2-Chloroanthracene
 and LUMOGEN RED. A peroxide unstable fluorescer (5,12-Bis(Phenylethynyl)
 Napthacene) is added. The resulting device glows a bright Peach color when
 activated by the end user. After 30-40 minutes, the Peach color fades and
 the Purple color is revealed.
 EXAMPLE 3
 A 6" Blue Glow Stick.RTM. Light Stick is made with a peroxide stable
 fluorescer 9,10-Bis-(4-Methoxyphenyl)-2 Chloroanthracene. A peroxide
 unstable fluorescer 5,16,11,12-Tetraphenylnapthacene is added. The
 resulting device glows a bright White color when activated by the end
 user. After 30-40 minutes, the White color fades and the Blue color is
 revealed.
 It is to be understood that while a certain form of the invention is
 described, it is not to be limited to the specific form or arrangement
 herein described. It will be apparent to those skilled in the art that
 various changes may be made without departing from the scope of the
 invention and the invention is not to be considered limited to what is
 described in the specification.