CA2048183A1 - High opacity solid marking composition - Google Patents

Abstract

ABSTRACT

A solid marking composition having an unexpected metallic sheen, a smooth, lipstick-like rub out, and unexpectedly enhanced opacity includes a metallic pigment and a nonmetallic colored pigment dispersed in a solid matrix. The solid matrix may be any suitable marking composition matrix, including a conventional wax and fatty acid matrix, a polyethylene resin matrix, or a polyethylene glycol resin matrix.

Description

EiIG~ OPACITY SOLID MARKING COMPOSITION

BACK5ROUND OF T~E INVENTION

1. Field of the Invention This invention relates in general to the ~ield of marking instruments, including crayons, and in particular, to solid compositions used in the manufacture of such instruments.

2. Brief Description Of The Prior Art That solid compositions used in the manufacture of crayonq and colored marking pencil~ may be produced from mixtures of waxe~, fatty acids, colorants and extenders is well known in the art of marking and writing instruments. ~hen properly formulated, such compositions may be u~ed to draw, write or color. Traditionally, these solid marking compositions have suffered from an inability to create a smooth~ even, and opaque mark and instead produce uneven lines of erratic intensity.
Conventional solid marking compositions in many instances also suffer from a lack of brilliance in color 2~ o the mark laid down, as well as a dull appearance of the ~olid marking composition itself. These inad2quacies Oe ~ t~ 3 available crayons can lead to disenchantment with the art capabilities of the crayon and loss of interest in usage of crayons.
One approach to achieving a more attractive marking composition has been to employ a metallic pigment, such as those prepared from metallic elements and their alloys, for example, aluminum, copper, gold, bronze and zinc. However, such compositions have employed the metallic pigment as the sole pigment in the solid marking composition for the purpose of producing a mark having the same appearance charac~eristics as the me~al itself.
Thus, the range of appearance effects which may be attained is limited by numbec of such metal pigments which may economically be utilized.
It is therefore one object of the invention to provide a solid marking composition which produces a marking instrument, such as a crayon, with a more appealing stick color.
It is also an object Oe the invention to provide a solid marking composition which imparts to the mark 1 id down by the crayon a unique appearance.
A eurther object of the invention i9 to provide a solid marking composition with superior tactile properties, including ease of application so as to produce a smooth flowing, even mark.
Yet another object is to produce a solid marking composition having improved opacity when applied to a surface .

ix~ ~ d~

SUMMARY OF TFIE INVE~NTION

The present invention is that the combination o~
a metallic pigment with a nonmetallic colored pigment dispersed in a solid matrix produces a solid marking composition yielding quite unexpected, but highly desirable, results.
First, the solid marking composition o~ the invention produces a colored mark which has an unexpected metallic sparkle, sheen, or glitter. The colored mark is, in addition, signieicantly more opaque in appearance.
Second, when the solid marking composition of the invention is used, for example, in the form of a crayon, the crayon stick has a surprisingly pearlescent appearance which is pleasing to the eye.
Purther, the composition of the invention produces a mark ~hich lays down on the surface in a very slick, smooth, "lipstick like" rub out, resulting in an unexpectedly enhanced ease of application, including better smoothnes3, glide, and color transfer.
Yet another unexpected property of the composition of the invention is that the stick color (masstone~ may vary signieicantly from the applied color (rubout), according to the choice of pigment components.
These uni~ue and surprising properties Oe the composition of the invention increase the appeal of the crayon for the consumers, including both children and artists. The appearance o~ the mark is improved over a conventlonal crayon in that the mark has a metallic sheen o~ sparkle which i~ much more pleasing to the eye. The application properties o~ the ~olid marking composition stimulate creativity and sel~-expression not normally ~ 3 encountered with traditional solid marking co~positions, such as conventional crayons. Such a smooth Elowing, more attractiv? mark increases the range oE uses for the composition and increases the breadth of the market for such a marking composition.
The solid marking composition of the invention is advantageously used in the manufacture of crayons employing any suitable matrix material. For example, the solid marking composition o~ the invention may utilize a conventional crayon matrix of paraffin wax and stearic acid, a so-calLed plastic crayon matrix of polyethylene resin and a plasticizer material, or a so-called washable crayon matrix material of water-soluble polyethylene glycol resins. In each, the composition of the invention produces a mark with unexpectedly superior tactile properties, a pleasing metallic sheen, and unexpectedly improved opacity.
The composition of the invention which achieves these results includes erom about 13 to about 40~ by weight of a metallic plgment, and from about 1~ to about 45% by weight nonmetallic colored pigments, dispersed in a suitable matrix.

DETAILED DESCRIPTION

The present invention in its most basic form is that the combination of a metallic pigment with a nonmetallic colored pigment dispersed in a matrix produces a solld marking compoqition producing a mark having a metallic sheen, spa~kle, or glitter. In one ~peci~ic embodlmentl a crayon, the composLtion of the invention 30 compri~es a combination o~ ~rom about 1~ to about 40~ by S~J ~Ji ~ ?~ ~-weight o~ a metallic pigment, from about 1~ to about 45~
by ~eight of a nonmetallic colored pigment, from about 16 to about 40% by weight inert fillers and extenders, and from about 50% to about 85~ by weight matrix materials.
The primary discovery is that the combination of a metallic pigment and a colored non-metallic pigment in a suitable matrix ~roduces a composition which unexpectedly achieves a colored mark which has a metallic sheen or sparkle in appearance. A further discovery is that the solid marking compositlon of the invention imparts a surprising pearlescent or sparkling appearance to the crayon stick itself. In addition, the colored mark produced by the composition has increased opacity and is laid down in a smooth "lip stick like" fashion, enhancing the tactile qualities of the crayon.
The metallic pigmen~s contemplated for use in the composition of the invention are prepared from metallic elements and their alloys, ~or example, aluminum, copper, gold, bronze and ~inc. Any of these may be used in the composition Oe the invention, depending upon the particular visual eefect desired~
The preferred metal is aluminum, and even more preferred is leafing aluminum. Aluminum is preferred because it imparts the desired qualities of pearlescent stick appearance, produces marks with a metallic sheen, and provides ease Oe laydown with a minimal intereerence with the actual color of the colored nonmetallic pigment.
Leafing aluminum imparts a greater metallic sheen to the mark laid down by the composition, while non-leafing 3~ aluminum impart~ more Oe a me~allic sparkle to the mark.

0~ course, combinations o~ two or rnore metallic pigments may be utilized to further broaden the range of appearance effects.
The more preferred leafing aluminum metallic S pigment is typically produced by g;inding aluminum to a powder in a wet ball mill containing a paint thinner or mineral spirits and a lubricant. Ordinarily, stearic acid is used as the lubricant in the mill, and the final product of lea~ing aluminum has a mono~olecular layer o~
stearic acid coating each ~lake of aluminum pigment.
Non-leafing aluminum metallic pigment is also suitable for the invention, however the effect upon the solid marking composition is to impart a glitter or sparkle look to the mark of the composition rather than a metallic sheen. Non-leafing aluminum metallic pigmen~ is also produced by grinding aluminum to a powder in a wet ball mill containing a paint thinner or mineral spirits and a lubsicant. To produce a non-leafing aluminum metallic pigment, however, an oleic acid is used a~ the lubricant in the mill.
Leafing and non-lea~ing aluminum metallic pigments are available in paste or in a powder form.
Commercially available aluminum metallic pigment contains only a nominal amount o stearic or oleic acid which remains as a microthin coating on the pigment particle.
Aluminum metallic pigment is available in a multitude of particle si%es.
The amount of metallic pigment which i~
necessary to yield the desired reqults is governed by the level Oe metalllc sheen or sparkle deYired, though a concentration Oe at least 1~ by weight i9 usually required to achieve a noticeable efect on the appearance and application characteristics of the composition. A
preeerred upper limit is about 40~ by weight, since greater amounts of aluminum metallic pigtnent may cvertake the coloring capability of the nonmetalllc colored pigment component.
When the solid marking composition is to be shaped into crayon form by a gravity molding process, a range of from about 4~ up to about 10~ metallic pigment is preferred, since ~reater amounts than about 10~ causes the solid marking composition to become too viscous for effective, efficient gravity molding application. Where, however, the solid marking composition i5 to be formed using such other processes as high pressure injection molding, extrusion molding, or press or tabletized lS molding, a range Oe metallic pigment of from about 153 up to about 40% is preferred, since a greater range of appearance effects can be achieved, and since maintaining a lower viscosity is not as critical to these processes.
Metallic pigments other than aluminum which may economically be used in the composition of the invention include zinc, copper, and bronze. These metallic pigments produce effects ~imilar to that of aluminum, however, they have a greater effect upon the color of the re~ulting compo itions. They typically p~oduce a mark with a deepe~, darker color than would be anticipated from the use of a colored nonmetallic pigment alone. Indeed, it has been found that compositions employing metallic pigment~ other than aluminum tend to be preferred for use in fine arts applications.
3n The ~econd componen~ of the solid marking composition is a nonmetallic colored pi9ment. Any conventional pigment which i9 compatible with the matrix material may be used, including inorganic pigments, organic pigments, and mixtures thereof. Typical inorganic pigments include iron blue, iron oxides, zinc oxide, ultramarine blue, lamp black, sodi~m rubine, and titanium dioxide. Typical organic pigments include azo, naphthol, and phthalo pigments. Additional pigmen~ materials such as acid dye toners, basic dye toners, acid dye lakes, and basic dye lakes may also be used. Various combinations of these pigments may advantageously be used.
The nonmetallic colored pigments are ordinarily used in amounts from about 1% up to about 45% by weight.
However, the amount of pigment utilized in a specific solid marking composition is determined by the desired color of thê solid marking composition, the coloring lS capacity Oe the pigment, and the desired application characteristics.
The third component o~ the solid marking composition of the invention is the matrix in which the pigments are dispersed. The matrix material is the substance which holds the solid marking composition together. Most solid matrix materials known Eor use in marking compositions are suitable for use in the present inventlon. So~e examples include a conventional para~fin wax and qtearic acid matrix, a plastic-based crayon ~5 matrix, and a polyethylene glycol resin matrix.
As is well known, a conventional crayon matrix includes a fatty acid component and a wax component.
Fatty acid~ which may be utilized a3 matrix material~ include ~uch materials as stearic acid and beef tallow~ Stearic acid is a solid member of the normal saturated fatty acid series present in most animal and vegetable eat~. It i~ a white crystalline solid generally ~3~

represented by the formula C17H35-CO2H. When stearic acid is mixed with waxes as a matrix material, it produces a structurally stable matrix. The stearic acid is generally softer than the waxes and is commercially available from a wide range of suppliers.
Beef tallow is the solid fat o~ oxen and is a mixture of tristearin, tripalmitin and triolein (tri-oleyl derivative of glycerol or any liquid oil obtained ~rom solid fats by pressure, to crude oleic acid ~ to potassium, sodium, or ammonium salt of sulphonate of oleic acid). Beef tallow is also generally softer than the waxes and also contributes mold release properties.
Paraffin ~axes are not true waxes but are mixtures o high melting point hydrocarbons. These waxes lS are white, translucent, waxy solids having 26 to 30 carbon atoms and have a wide range o~ melting points. The best results, in terms of strength, structural integrity, and laydown properties, are achieved by utilizing a blend of low, medium, and high-temperature melting paraffin waxes.
Microcrystalline waxes are derived from the heavy residual lubricating oil ~raction o~ crude after removal of paraffin wax. ~hese waxes closely resemble natural waxes in that they h~-e a high melting point, high viscosity, and high adhesion and cohesion. ~he waxes are commercially available from a number of manufacturers.
When the solid mar~ing composition u~ed in the form of a conventional crayon to be shaped by a gravity molding process, a wide range of content of matrix material ls suitable. However, a range of matrix materlal~ o from about 40~ up to about 60~ is mo~t preferred when the composition i~ to be used in the ~orm o~ a crayon. This range leads to the be~t per~ormance by the resulting solid marking composition, including laydown and general marking characteristicst as well as structural integrity of the formed solid marking composition. When the matrix content o the composition is below about 40~
or above about 60~ weightt the ~ormed sticks tend to lose strength, and their application characteristics become less desirable.
When the composition Oe the invention is in the form of a conventional crayon, a mixture of matrix materials is most useful. The most preferred combination of matrix materials when forming the compositlon into a conventional crayon comprises from about 50% to about 75 by weight fatty acid and from about 25% to about 50%
paraffin wax. While combinations of wax and fatty acid outside of these ranges are workable, they tend to produce solid marking compositions which lay down rather thln films of colorant which have a weaker apparent color.
When the composition of the invention is in the form of a plastic crayon, the matrix material is preferably comprised of polyethylene resin and a plasticizec which is compatible with the resin. In general, it has been found that the inclusion in the compo3ition of a plastic crayon Oe erom about 15~ up to about 50% by weight of a polyethylene resin produces an acceptable marking composition. The compatible plasticizer, the function of which is to provide the composition with good application characteristics, is typically effective when present in the range ~rom about 20~ up to about 55~ by weightO The be~t results are achieved when excluslvely high density polyethylene re~ins (density of at least about 0.95) are employed, since the best balance o~ prope~ties may be achieved while avoiding bloom.
When the invention is in the form of a washable crayon, the matrix material is comprised of polyethylene glycol resin. Such a washable crayon composition may also optionally include one or more of a plasticizer, a surfactant, a viscosity modifier, a filler, an antifoam agent, or a mold release agent. For the purpose of producing a marking composition useful in the form oE such a washable crayon, the polyethylene glycol resin should usually be present in an amount of from about 7~ up to about 85~ by weight. In addition, the be~t properties are attained when polyethylene glycol resins having a molecular weight below about 7,000 are avoided, since the lower molecular weight materials are undesirably hygroscopic.
Where the solid marking composition is to be used in the orm of a colored marking pencil lead, the wood or plastic sheathing provides structural support, and the structural integrity of the composition is less impoctant and the concentrations of the matrix materials may be varied accordingly.
An inert filler or extender may also be beneficially added to the composition of the invention to provide added strength and structural integrity. Typical fillers or extenders include talc, felspar, T-clay, mica, calcium carbonate, and glass and plastic microspheres. A
filler or extender is normally used in an amount of from about 1~ up to about 40~ by weight. These material~ are utili~ed a~ inexpensive eillers once sufficient pigment has been added to the composition to achieve the desired color. The amount of filler or extender utilized depends upon the type of color desired and the type of pigment utilized.
Mica does not contribute substantially to the laydown or per~ormance when used in combination with a leafing aluminum metallic pigment and merely acts as a filler. When used in conjunction with other metallic pigments however, the mica tends to imp~ove the laydown of the mark o~ the composition. The remaining fillers and extenders have little to no eefect upon the marking characteristic~ of the solid marking composition.

The eollowing solid marking compositions are formulated as examples of the present invention.
Examples 1-8 are representative of the solid marking composition in the form of a conventional crayon.
The crayons were produced by the following process. First, the wax and stearic acid were melt blended at a temperature in the range of about 210~F to about 250F. The non-metallic colored pigmenti were then ground with talc to produce a dry color blend. To the wax and stearic acid melt were added the dry color blend, additional talc, T-clay, or mica, and the metallic pigmentq. The molten blend was then agitated or mixed to provide adequate dispersion o~ the dry components, poured into molds, cooled, and ejected.

Example 1 Example 2 31ack Crayon Blue Crayon Co~ponent lbs wt ~ lbs wt ~
stearic acid 60 41.1 60 41.9 S paraffin wax 60 41.1 60 41.9 talc 14 9.6 14 9.8 dry color pigments leafing aluminum 8 5.5 7 4.9 lamp black 4 2.8 phthalo blue 2 1.4 Example 3 Fxample 4 Green Crayon Red Crayon Component lbs wt ~ lbs wt ~.
stearic acid 60 40.0 60 40.0 15 paraffin wax 60 40.0 60 40.0 talc 16 10.7 16 10.7 dry color pigments leafing aluminum 8 5.3 7 4.6 sodium rubine 7 4.6 phthalo green 6 4.0 Example 5 Blue-Green Example 6 Crayon Purple Crayon Component lbs wt ~ lbs wt 25 stearic acid 60 41.1 60 42.0 paraffin wa~ 60 41.1 60 42.0 talc (300 mesh~ 10 6.8 10 6.9 dry color pigment~
leafing aluminum 8 6.8 6 4.2 blue-green 8 6.8 royal purple 7 4.9 Example 8 Example 7 Strawberry Violet Crayon Crayon Com~onent lbs wt ~ lbs wt ~
stearic acid 60 39.5 60 40.9 paraffin wax 60 39.5 60 40.9 talc (300 mesh) 10 6.6 15 10.2 dry color pigments leaeing aluminum 8 5.3 7 4.8 violet 2 1.3 violet-red 12 7.9 2 1.4 wild strawberry 2.5 1.7 The compositions of Examples 1 8 had acceptable working properties when formed into crayon sticks by conventional gravity molding teohniques. In addition, the crayon sticks had a pleasing pearlescent appearance, a smooth, lipstick-like rub out, and a mark of enhanced opacity compared to a standard crayon.

To formulate the so1id marking composition of the invention in the eorm o~ a plas~ic crayon, a matrix material of polyethylene resin and a compatible plasticizer i used. Examples 9-12 are representative of the solid marking composition utilized as a plastic 25 crayon.

Example 9 Example lO
Red Crayon Blue Crayon Component lbs wt ~ lbs wt stearic acid 17 32.1 17 30.9 paraffin wax 18 33.9 18 32.7 high density poly- 12 22.6 12 21.8 ethylene dry color pigments leafing aluminum 3 5.7 7 12.7 naphthol red 3 5.7 phthalo blue l 1.8 Example 11 Example 12 Black Crayon 31ue Crayon Component lbs wt ~ lbs wt %

15 SteariG acid 13 25.5 13 25.5 parafin wax 19 37.2 l9 37.2 high density polyethylene 14 27.4 14 27.4 dry color pigments leafing aluminum 3 5.9 2.5 4.9 sodium rubine phthalo green 2 3.9 royal purple 2.5 4.9 The compositions of Examples 9-12, when formed into crayon sticks by conventional injection molding technique~, have a good balance of physical and application properties, with no bloom. The crayon sticks have a pleasing, pearlescent appearance, a smooth rub out, and a mark of enhanced opacity.

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EXA~PLES 13-15 To ~ormulat~ the solid marking composition of the invention in the form o~ a washable crayon, a ~atri~
material of polyethylene glycol resin i5 used. Examples 13-15 are representative of the solid marking composition utilized as a washable crayon.

Example 13 Example 14 Red Crayon Blue Crayon Component lbs wt ~ }bs ~_~
10 polyethylene glycol 15 10.3 15 10.3 resin ~m.w.=15,000-20,00o) stearyl alcohol 39 26.7 39 26.7 oleyl alcohol 9 6.2 9 6.X
15 polyethylene glycol 24 16.4 24 16.4 monostearate polyethylene glycol 35 24.0 35 24.0 distearate dry color pigment~
leafing aluminum 3 2.0 7 4.8 naphthol red 3 2.0 phthalo blue 1 0.7 talc (300 mesh) 18 12.3 16 lO.9 h '~ ,3 ~

Example 15 Red Crayon Component lbs wt ~

polyethylene glycol 15 10.3 S resin ~m.w.=15,000-20,00a~
stearyl alcohol 39 26. 7 oleyl alcohol 9 6.2 polyethylene glycol 24 16.4 monostearate polyethylene glycol 35 24.0 distearate dry color pigments leafing aluminum 3 2.4 sodium rubine phthalo green 2 1.6 royal purple The compositions of Examples 13-15, when formed into crayon sticks by conventional gravity molding 2V techniques, have good strength and working properties, and their marks are readily washable from textiles and other surfaces. The crayon sticks have a pleasing pearlescent appearance, a smooth rub out, and a highly opaque mark.
From the foregoing description and examples, it is apparent that the objects o~ the present invention have been achieved. The solid marking compositions of the invention produce marks which have a metallic sheen. The marks lay down with a lipstick-like rub out alld the b ~ C~

opacity is unexpectedly increased. When the composition is used in the form of a crayon, the crayon stick has an unexpected metallic sheen or pearlescent appearance.
While only certain embodiments have been set forth, alternative embodiments and various modifications will be apparent to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope o~ the present invention What is claimed is:

Claims (19)

1. A solid marking composition comprising a pigment dispersed in a matrix, said pigment having a metallic pigment component and a nonmetallic colored pigment component.

2. A composition according to claim 1 wherein:
(a) said metallic pigment component is present in an amount from about 1% to about 40% by weight, and (b) said nonmetallic colored pigment is present in an amount from about 1% to about 45% by weight.

3. A composition according to claim 1 wherein said matrix comprises:
(a) from about 15% to about 50% by weight polyethylene resin, and (b) from about 20% to about 55% by weight of a compatible plasticizer.

4. A composition according to claim 1 wherein the matrix comprises from about 7% up to about 85% by weight polyethylene glycol resin.

5. A composition according to claim 1 wherein said metallic pigment is selected from the group consisting of metallic aluminum pigment, metallic copper pigment, metallic zinc pigment, and metallic bronze pigment.

6. A composition according to claim 5 wherein the metallic pigment is a leafing metallic aluminum pigment.

7. A composition according to claim 1 wherein the metallic pigment is a metallic copper pigment.

8. A composition according to claim 1 wherein the metallic pigment is a metallic zinc pigment.

9. A composition according to claim 1 wherein the metallic pigment is a metallic bronze pigment.

10. A composition according to claim 1 wherein said nonmetallic colored pigment component comprises at least one pigment selected from the group consisting of inorganic pigments, organic pigments, and mixtures thereof.

11. A composition according to claim 10, wherein said inorganic pigment is selected from the group consisting of iron blue, iron oxides, zinc oxide, ultramarine blue, titanium dioxide, lamp black, sodium rubine, and mixtures thereof.

12. A composition according to claim 10, wherein said organic pigment is selected from the group consisting of azo, naphthol, and phthalo pigments.

13. A composition according to claim 1, wherein said nonmetallic pigment component further comprises a component selected from the group consisting of acid dye toners, basic dye toners, acid dye lakes, basic dye lakes, and mixtures thereof.

14. A composition according to claim 1, wherein said nonmetallic colored pigment component has a particle size in the range of from about 0.1 microns up to about 75 microns.

15. A composition according to claim 1 wherein said matrix material comprises a fatty acid and at least one material selected from the group consisting of paraffin waxes and microcrystalline waxes.

16. A composition according to claim 15 wherein said fatty acid is stearic acid.

17. A composition according to claim 1 further comprising at least one filler selected from the group consisting of talc, feldspar, T-clay, mica, calcium carbonate, glass microspheres, and plastic microspheres.

18. A composition according to claim 15 wherein said matrix comprises from about 50% to about 75% fatty acid and from about 25% to about 50% paraffin waxes.

19. The composition of claim 1 in the form of a crayon stick.