USRE23722E - Translucent metallic enamel and a - Google Patents

Description

Oct. 13, 1953 R. E. PIK E Re. 23,722

TRANSLUCENT METALLIC ENAMEL AND A PROCESS OF MAKING IT Original Filed Sept. 30. 1948 FIG. I.

VALUQ PURPLE CHROMA 4-- HUE GREEN BLUE INVENTOR. RALPH E. PIKE ATTORNEY Reissued Oct. 13, 1953 TRANSLUGENT METALLIC ENAMEL AND A I PROCESS OF MAKING IT Ralph E. Pike, Flint, Mich.,

Pont de Nemours and Company,

assignor to E. I. du Wilmington,

DeL, a corporation of Delaware Original No. 2,604,414, dated July 22, 1952, Serial September 30, 1948. Application for reissue July 21, 1953, Serial No. 370,909

(Cl. 106-173) Matter enclosed in heavy brackets I: II appears in the original patent but lorms no part of this 17 Claims.

reissue specification; matter printed in italics indicates This invention relates to lacquers and synthetic enamels and particularly to such coating compositions which possess a translucent metallic appearance and which are currently popular for automobile finishing.

A customary requirement for coating compositions is opacity in relatively thin films, a property commonly referred to as hiding power. Although desirable in some of its aspects, this opacity limits the appearance of a film of coating composition to the colors reflected from its surface. In the past few years, coating compositions which have a transparent appearance and relatively low hiding power, but which possess a desirable "depth," luster, and metallic appearance, have been very popular, particularly as automobile finishes. In this case depth does not involve intensity as in the term "deep color." Rather, it means the optical illusion of distance or thickness characteristic of metallic finishes. The metallic appearance is diflicult to describe, but it might be regarded as the optical sensation resulting from the multicolor effect produced by a somewhat translucent coating composition partly by the light reflected from the surface, and partly by the light transmitted by the translucent film and ultimately reflected by aluminum flakes in the film.

A coating composition described as being metallic in appearance possesses the following char acteristics, to some degree, simultaneously: (1) An appearance of depth or distance in the film, (2) An ability to change color depending on the nature and direction of the illuminating source, (3) The ability to high light, or attract attention to, changes in contour of the finished article (for instance, body design of automobiles), and (4) a multi-color or polychromatic efl'ect on flat surfaces. Thus, it is common in the coating composition industry to refer to overall metallic effect rather than to attempt to identify the specific quality that is present or absent. Since no composition is known which possesses a maximum of all four characteristics, useful coating compositions are selected on the basis of the most favorable combination of those characteristics.

In the description of this invention the terms for the qualities of color will be based upon the definitions given in the Munsell Book of Color the additions made by reissue.

by A. H. Munsell. Hue" is the name of a color, as red or green-the first characteristic that the eye detects. Value" is'the amount of light in a color; how light or dark it is, or how nearly white or black it is. Chroma is the strength of the color; how strong (intense) or weak (gray) it is.

U. S. Patents 2,140,745; 2,335,760; and 2,384,579 describe means of accomplishing some degree of transparency in nitrocellulose lacquer and synthetic enamel compositions. Essentially these methods retain the principal pigment in a state of very fine division sothat its transparent prop-- erties may be utilized, in conjunction with aluminum flakes, to produce the above-mentioned desirable metallic appearance. U. S. Patent 2,140,745 covers the process of flushing pigments from the wet pulp stage directly into uniform dispersion in lacquers without the intermediate steps of drying and pulverizing the pigment. While applicable to some degree with all pigments, the process is must useful with those ordinarily manufactured by chemical precipitation from water solution. U. S. Patents 2,335,760 and 2,384,579 prepare iron oxide pigments capable of being flushed into lacquer or enamel vehicles so that the verysmall primary particles of the pigment do not agglomerate to any marked extent and so that the nature of the particles is not substantially changed from their freshly-precipitated condition. Thus, durable, lightfast and relatively inexpensive pigments of comparatively high transparency and low hiding power are made available for use as the principal, or so-called prime pigment in lacquers and synthetic enamels for outdoor exposure. In low concentrations these colloidal hydrated or hydrous ferric oxides impart an amber tinge to the filmforming component of the coating compositions. In higher concentrations, the color is a translucent gold, brown, or reddish brown. In the actual use of the iron oxides, it has been necessary and desirable to add to the iron oxide base composition closely controlled amounts of selected relatively opaque tinting or toning pigments, suitably dispersed in a useful vehicle, to impart opacity or hiding power, at the same time coloring the composition to the desired hue. Small quantities of selected flaked aluminum pigment added to this mixture increase the "value" or lightness oi the color and provide the metallic appearance. However, when these hydrousiron oxide bases are shaded by orthodox methods using conventional pigments-black, white, maroon, blue, green and yellow-either of two things occurs: (1) So little shading pigment is used that the hiding power is insufilcient or an amber or brownish tone from the hydrous iron oxide is visible, limiting the color range of finished compositionsto browns and olive greens. (2) So much shading pigment is used that the excellent outdoor durability of the hydrous iron oxide in the coating composition is overcome by the comparatively poor outdoor durability of the shading pigments, which in most cases are notably inferior to hydrous iron oxide in color- Iastness, chalk-resistance, and general resistance to film deterioration. For instance, excessive amounts of phthalocyanine blue and green pigments, while providing satisfactory light stability, produce a dull red chalk or bronze under normal exposure conditions. Excessive amounts of aluminum fiake cause dulling and aluminum chalking. Carbon black and lamp black pigments, of the low tinting strength type required to maintain low aluminum concentration, show early dulling and chalking on exposure.

In order to obtain maximum freedom from aluminum mottling or flooding (heterogeneous pigment pattern in the applied film) in practical metallic enamel formulations, a minimum concentration of aluminum in the enamel is essential. Unfortunately, brightness and lightness increase with aluminum content, and the brighteniors are currently the most popular ones for articles commonly finished with metallic" colors. These bright colors can be made by any of the following methods.

- A. Use of high aluminum concentration resulting in severe flooding or mottling tendencies and early dulling on exposure.

B. 'Use of a combination of aluminum and nonchalking opaque white pigments, which invariably results in a sacrifice in metallic appearance over alternate A.

C. Use or a maximum oi low tinting strength, transparent type pigment and a minimum of strong toning pigments, by the complementary blending principles as described in this invention.

It has been desirable to prepare enamels and lacquers with a greater variety of hues, improved metallic appearance, and improved outdoor durability, using the iron oxides of U. 8. Patents 2,335,760 and 2,384,579. It has also been desirable to accomplish essentially the same results by finding and using, as additives to or substitutes for the hydrous iron oxides, prime pigments which possess the desirable properties of transparency, low tinting strength, and good durability, capable of being tinted to the desired hue with relatively minor quantities of light-fast toning pigments that are strong (high in chroma), relatively opaque, high in tinting strength, and that preferably but not necessarily possess good durability in enamel films.

Accordingly, the purpose 01 this invention is to provide improved synthetic enamels and lac quers which are durable, lustrous, translucent and metallic in appearance. A further object is to make new durable, relatively inexpensive colored coating compositions, suitable for finishing automobile exteriors, which possess metallic efi'ect to an unusual degree. Another object is to make durable gray lacquers or enamels without chromatic effect.

the use of black or white pigments. Still another object is to make a pigmented composition of a specific hue using a pigment 01' that hue or an equivalent blend oi. more than one pigment in only minor portions withrespect to the total pig merit present. An additional object of this invention is to provide a method oi! using the desirable properties of hydrated iron oxide pigments in enamels and lacquers possessing better durability and a wider variety of hues than heretofore avaialble. Other objects will appear as the invention is described.

There are no known pigments which individually impart all the desired properties discussed above to a, synthetic resin metallic enamel, but by selecting pigments according to the new procedure .oi the presentinvention, pigments which otherwise are undesirable can be combined to produce brilliant, durable beautiful metallic finishes which are substantially non-chalking and non-fading.

The objects of this invention are accomplished fundamentally by using the hydrous iron oxide pigments described in U.. S. Patents 2,335,760 and 2,384,579 in combination with one transparent pigment, or a blend of two transparent pigments, relatively complementary to the iron pigment so that the yellow nature of the latter is substantially neutralized to a true gray or to a grayish base of the same hue as that desired in the final color. Then a tinting pigment of that hue, but of higher chroma, or an equivalent blend' a way that it (or one of them) can be used in excess oi the required neutralizing quantity to produce the desired color. This method reduces the number of pigments required and simplifies the application or this invention to commercial enamel manufacture. Finally, the value or lightness is adjusted by adding flaked aluminum pigment. The resulting composition possesses simultaneously the desired hue, chroma, and value along with the most favorable combination of the four characteristics of a metallic enamel: depth, apparent color change, high lighting, and poly- While the above description is based on hydrous iron oxide pigments, the same principle is applicable to other prime pigment bases, as will be explained later.

In the attached drawing, Figure 1 shows the three dimensional diagrammatical concept of color characteristics. The vertical axis is value (from black to white), the horizontal axis is chroma (from neutral gray at the center to stronger color away from the center and the radial or angular location on any given value plane is hue. Figure 2 is a vertical view oi. the same system, a. two dimensional view showing only hue and chroma, the qualities most important in this invention. The numbered positions on Figure 2 show the approximate hue and chroma oi the eight pertinent pigments. Figures 3 and 4 are vertical diagrammatic views similar to Figure 2 and are described more fully hereinafter.

It is to be understood that throughout the examples, the pigments are in the form of mill bases prepared by dispersing the pigment in a suitable vehicle by grinding in a ball-, roller-, pebble-, or buhrstone-mill, by other suitable dispersing methods, or in some cases by the proccases or U. 8. Patents 2,140,745 and 2,384,579.

TABLE 1 Pigment key Description ote Medium Particle Site Channel Carbon Black. Lam Black D Ferrite Yellow Orange. Synthetic Red Iron Oxide. 40% P011901 Blue Lake. Milori Blue (Ferric Ferrocyanide).

Precipitated Hydrous Iron Oxide (Water Wet) (Note 1) U.S.P. 2,335,760. Vat Thioindigoid DyestuiiIndo Maroon.

Nor! l.-In all the enamel compositions oi the examples, the per centage of pigment is on a pigment solids basis.

Nora.2.Pigm'ent 7 can further be described as an "extra line aiuminum lining paste (non-1eailng), in which substantially no flakes are as large as 20 microns in diameter and substantially all of the flakes are less than micronin diameter.

N01! 3.Pigment 8- can further be described as a "standard aluminum paste (leailng), in which about 40% of the total surface area is composed of flakes with a diameter larger than 20 microns.

In Table 1 pigment l is a prime or transparent base pigment composed of iron oxide in chemical combination with water, an example of which is disclosed in U. S. Patent 2,384,579. Pigment 5 and 6 are prime pigments possessing qualities comparable to prime pigment l in durability, lighti'astness, transparency, and tinting strength. Hence they are substantially equivalent to pigment l in the principle of this invention, but being diil'erent in hue and chroma, they produce different families of colors when substituted for pigment I. Pigment i6 is similar to i but is prepared according to U. 8. Patent 2,335,760. In the claims the term hydrous iron oxide is intended to refer to pigments substantially equivalent to those'prepared according to either of the patents Just mentioned above. Pigments 2, 3 and 4 are transparent tinting or toning pigments possessing high tinting strengt, high chroma, lightiastness, and reasonably good outdoor durability.

A durable transparent metallic neutral gray without black or white pigment will serve as a fundamental example of an automotive enamel of this invention. In this case it is desired to neutralize the hue and chroma of pigment i, yet retain a preponderant proportion of pigment I in the finished enamel in order to utilize its trans parency and durability to an optimum degree.

6 Figure 3 is a graphical representation of the pigmentation. Since there is noknown pigment completely complementary to pigment I, proportions of 2 and I are blended to produce an intermediate hue II, which is substantially complementary to I. Then blend I8 and pigment i are blended in the proper proportions to produce IS.

a neutral gray possessing substantially no line or V chroma. Pigment 3 might be substituted for pigment 4. A blend of 2 and 3, complementary to I, would have a. higher chroma than blend l8 and would require larger proportions of pigment I to produce a neutral gray. The enamel thus produced would possess greater transparency, less hiding power, and a different metallic and than the same color gray enamel made with pigments I, I and I. In either case, a small amount of a flaked aluminum pigment is added. This lightens the color to the desired value and contributes to the metallic effect.

The final steps in producing a finished enamel are reduction to the desired pigment to hinder ratio with additional vehicle, introduction of driers and other modifiers, and adjustment to the desired viscosity with suitable solvents.

The method of this invention for pigmenting an enamel possessing hue and chroma, as contrasted with a neutral gray, is described as follows for a grayish blue metallic enamel. The desired hue and chrome. were selected and are represented by the point 20 on Figure 4. To arrive at this hue and chrome, pigments 2 and 3 are blended in proportions yielding blend 2| which is complementary to pigment l. Blend 2! and pigment I are mixed in proportions yielding blend 22 which is on an extension of a straight line connecting 2 and 20, so that by adding pigment 2 to blend-22 in small increments color 20 is approached and reached.

While the theory of producing a durable gray and a grayish blue metallic enamel have been explained above, the invention will be more completely understood from the examples listed in Table 2, in which the parts are by weight. The examples are largely shown in tabular form for convenience of comparison. The column or row headings are identified. as follows:

Complementary Blend is blend of pigments to produce an improved metallic enamel of a desired color by this invention.

Conventional Blends I and II are alternative blends of conventional pigments commonly used in metallic enamels of the same color as the corresponding Complementary enamel. Two alternatives are given for comparative purposes. For instance Color B Gray is substantially the same color in its three modifications, namely; Complementary, Conventional I, and Conventional 11.

TABLE 2 Metallic enamel compositions Complementary Blend Conventional Blend I Conventional Blend II Matched Color Pigment Pigment Pi ent P/B P/B P/B gm Ratio Ratio Ratio No. Color V Percent No. Color Percent N 0 Color Percent (A) Gray 9.2/ 8.7/liX) TABLE 2Continued Metallic enamel compositions Complementary Blend Conventional Blend I Conventional Blend II MatchedColOr f PB i me t P/B Pigment PIE e t Ra tio Ratio Ratio No. Color Percent No. Color Percent No. Color Percent g4) grelertnun 1g ggick T25 2) ice r 1 Y 11 51 12) Yellow Tr (B) Gray 9'3/100 E7;Al u i ll1um 30 102/100 g'olmo 7)Aluminum 75 Total 100 )Blu 16 (2) Vlcfiet 5(4) 6 1. o Green-Gray 0.4/100 E ff g j 30 913/100 00 Total 100 lfilg l ivi'if" 3 15 o 10) Black"; 12 (D) Blue-Gray.. 8.2/100 (9)Alummum I 8.9/100 (9) 44 9.6/100 Total In Total. 100

(3) Blue 11 (11) Black n (a) Blue.. IIII "5 (E) Gray (9)Aluminum 42 (9 Aluminum ca Total 100 Total "R 112 Black. 3 5 10 e 16 (6) Yellow 57 12) Yellow 54 (3mm (9)Aluminum 30 I (9)Aluminum, a1 J 9 Aluminum 25 Total 1(1) 100 1(1) are "i are e a; as 2 inc e e 3 Blu 1 Yellow 14 (1) Yellow l6 (G) Gray 15.3 100 S f 23 8.1/100 (8) Aluminum... 60 (8) Aluminum Total 100 TotaL. 100 Total 100 (5)81'4221: 55 (10131118 88 (gxl ill n 55 11) Black l (n) Blue 12.3/100 Aluminum 9.3/100 8) Aluminum Total 100 Total IR Trace.

P/B is a designation for the ratio of total pigments to solid vehicle by weight. This refers to the final enamel produced, using the pigment blends in the table. Variations in P/B ratio occur because each pigment is dispersed (or ground) separately with small quantities of liquid vehicle to produce a mill base. For commercial production reasons, mill bases do not necessarily have the same P/B ratio.

The following formula represents a typical baking enamel vehicle for all of the tabulated pigmentations in which the parts are by weight:

49% linseed oil-China-wood oil glyceryl The thinner or solvent content 01 the final enamel is variable because it is common practice to prepare enamels at a. uniform viscosity rather than at a constant percent oi volatile solvent. Therefore, variations occur from color to color and often even between diflerent batches of the same enamel. The viscosity of the baking enamels was 37 seconds :4 seconds in a Parlin #10 viscosity cup at 25 C. A suitable baking schedule for these products applied to metal substrates was 1 hour at 225 F.

The following formula is a typical air drying vehicle for illustrating all of the tabulated pigmentations in which the parts are by weight:

49% linseed oil-China-wood oil glyceryl The final volatile solvent content varied as described under the baking vehicle.. The viscosity of the air drying enamels was the same as for the baking enamels.

An example of a finished synthetic resin enamel typical of those intended in this invention, using the above'air drying vehicle as a basis, is as iollg'wa The parts are by weight. The

pigmentation is taken from Complementary Color A, Gray. of Table 2:

The following are examples of the application of this invention to nitrocellulose or lacquertype compositions. For direct comparison, the pigmentation of synthetic resin enamels of sub-- stantially the same color as the first two lac- Pigment 3, blue 0.454 5 Pigment 2' viulet 0247 quers is shown. In all compositions black and Pigment yellow 2,167 wh t pi m nts are absent, and the pigment Pigment l, aluminium 1.22s m in ns are based on the principles or this 49% linse d oil-China-wood 1 r' 1 invention. It is to be understood that in the phthalate resin 24.527 lacquers. 'as in the synthetic resin enamels, all 52% linseed oil glyceryl phthalate resin- 2.701 pigments had been previously dispersed in a suit- 50% soya oil-China-wood oil pentaerythable vehicle (usually nitrocellulose for the lacritol phthalate resin 6.599 quers) by methods known to the art.

TABLE 3 o l w B1 1 sienna... a. siesta-snail Matched Color P/B Pix e PIB Pig ent Ratio I Ratio No.'. Color Per Cent No. Color .Per Cent 16 Yll 11% Mt e; it? t tfifiilii t'i'tg (nm w 51 3 fiffig g gfii 2 /100 g Total Ho- 2 '(K) Brown /10 15.4/100 g; xig g 'fi i:::g i Total -.lw.0

E 16) 7) (L) Gray 11.3 100 (3) o 2; 2 7 (LDGray 8.551100 17) .s 2

5 .9 git; .3 02 [Dark Gray] om 11.31100 Gm 2s niumiimifinlilii Total. l00 o (0) Green 9.1/100 33% China-wood oil phenoliormaldehyde varnish (solid) 0.392 [Dried] Drier solution (16% lead) 0.654 Drier solution (3% manganese) 0.436 Drier solution (2% cobalt) 0.872 Hydrocarbon solvent (volatile) 59.723

In Table 3, the synthetic resin enamels may be made with either a baking or an air dry vehicle.

A suitable vehicle for the lacquers in Table 3 has the tollowing analysis, by weight:

The cellulose nitrate in this composition is the conventional lacquer type, having a viscosity of about 6 seconds in Formula of A. s ."r.'m., 1:- 301-33.

Brown Lacquer J of Table [2] 3, using this vehicle had the following composition, by weight:

lfledor modified with non-drying oils, semi-drying oils, or drying oils such as cocoanut oil, soy

Per cent Pigment ll, yellow 1.4 Pigment I green 0.2 Pigment ||,:f!naroon 0.2 Pigment I, aluminum 1.0 Cellulose nitrate 17.1 50% cocoanut oil glyceryfph halate resin 8.6 Dibutyl phthalate 3.5 Blown castor oil 2.4 Butyl acetate 23.6 Methyl ethyl ketone 10.5 Methyl isobutyl carbinol 5.3 Toluene .43 Xylene 4.9 Ethyl alcohol 9.8 High solvency naphtha. 6.6

In the claims the term "perpcnderant as applied to the transparent prime pigment means that it is present in amount greater than any other single pigment. The term transparent pigment" refers to a pigment which when dispersed in an organic vehicle has low hiding power and transparency as distinguished from a relatively opaque pigment with relatively high hiding power. In the former case the transparency of the pigment allows the light to reach the aluminum particles giving the fllm [for] a high metallic [brialliance] brilliance whereas an opaque pigment would mask thereflection giving a dull, lifeless film.

The aluminum powder used in the compositions of the present invention are widely available commercially in the form of mineral spirit pastes. They are made in leaflng and non-leaiing gradesand also in line grades called lining" pastes or coarser grades called "standard" pastes. Any grade may be used, but the standard" grade which is considerably coarser than the linings grade imparts a much greater brilliance to enamel films giving thm an unusual apparent depth. For this reason the"standard rade of aluminum paste is preferred hi both cellulose derivative and synthetic resin enamels of this invention where a maximum degree of reflection is desired.

The proportions of pigments may vary to give a large assortment of colors and effects; but in the preferred embodiment of the invention, the

prime transparent pigment (A) of the claims v may vary between and 85.7% by weight of the total pigment in synethetic resin enamels and between 50.2 and 84.2% for cellulose derivative lacquers.

The relatively transparent complementary pigments B and tinting pigment C- of the claims may vary in the preferred embodiment from 11% to 45% combined in synthetic resin enamels and from 4.7% to 44.6% in cellulose derivative enamels.

The aluminum powder D of the claims may vary from 3.1% to in synthetic resin enamels and from 4.5% to 36.4% in cellulose derivative lacquers.

The principles of pigmentation for coating compositions with a metallic appearance disclosed 'in this invention are applicable to all types of oil, and linseed 011, respectively; (2) cellulose derivative film-forming agents; (3) vinyl type materials such as vinyl, acrylic, and allyl resins; (4) ureaformaldehyde type resins; (5) melamine formaldehyde resins; (6) phenol formaldehyde resins and oleoresinous compositions prepared therefrom; and ('7) miscellaneous film-forming materials such as silicone resins.

The principles of pigmentation of this invention pertain also to durable, lightfast, transparent, low tinting strength, low hiding pigments other than the prime pigments which are shown as examples of the type most useful, namely, the hydrous iron oxides I and It, the yellow 6, and the green 5, which contribute predominately to the transparency and outdoor durability of the products. [Tinting] Transparent tinting and toning pigments other than violet 2, blue 3, green 4, and maroon I I will be found useful in the practice of this invention; and those listed .are used (coarse) and 9 (fine) listed in Table 1 each contribute to a different degree to the metallic appearance of a finished enamel. Pigment 8 (coarse) is preferred where the most brilliant metallic appearance is required. Pigment 9 (fine) gives a less brilliant effect and I yields the least brilliance of the three listed, although even enamels prepared from the latter are attractive and useful products.

It is obvious to one skilled in the art that useful coating compositions can be made within the scope of this invention using other prime or transparent base pigments, other tinting pigments, and other grades of aluminum pastes, resulting in the improvements set forth previously, although those used in this disclosure are currently preferred because the resulting colors are at present the most popular where metallic enamels are largely usedautomobiles and certain other commercial articles.

The advantages of the enamels of this invention over conventional metallic coating compositions are depth, high-lighting of colors, apparent color change when viewed from different directions or under different light, and polychromatic appearance; and, in addition to these, a marked improvement in outdoor durability over conventional metallic enamels in gloss retention, color retention, and general film integrity, including freedom from bronzing, chalking, checking, and cracking. The application properties and resistance to aluminum mottling of the metallic enamels of this invention are equal to, or better than, the duller and less brilliant conventional metallic enamels and are far superior to conventional products which have had large quantitles of aluminum flakes added to enhance the metallic eflect.

It is apparent that many widely diflerent embodiments of this invention may be made without departing from the spirit and scope thereparent pigment substantially complementary in color to the said prime pigment in amount to yield a gray when mixed separately therewith;

r (C) at least one colored tintins pigment and (D) flnely divided flake aluminum metal.

2. The composition of claim 1 in which the pigment B is a lake of dichloroisodibenzanthrone on barium rosinate.

3. The composition or claim '1 in which the pigment (B) is phthalocyanine blue.

4. The composition or claim 1 in which the pigment (B) is phthalocyanine green.

5. The composition oi claim '1 in which the pigment (B) is vat thioindigoid dyestutbindo maroon.

6. The composition or claim 1 in which the aluminum flake is relatively coarse and about 40% or the total aluminum surface area is composed of flakes with a diameter larger than 20 microns.

7. The composition of claim 1 in which the pigment (A) is present in amount between 11% and 85.7% by weight of the total pigment; complementary pigment (B) and tinting pigment (C) combined are present in amount between 4.7% and 45%; and aluminum flake powder (D) is present in amount between 4.5% and 36.4%.

8. The composition oi. claim 1 in which the vehicle contains a synthetic resin and the pigments are present in amount as follows:

(A) 25% to 85.7% by weight (B) and (C) 11% B 45%v (D) 3.1% to 30% 9. The composition of claim 1'in which the vehicle is a nitrocellulose lacquer and the pigments are present in amount as follows:

ments, one of which is in excess oi! the amount necessary to produce a pigment (A), the said excess color complementary to being pigment (C).

- sitions adapted to produce tough, durable 1m- Reference, Cited in the file 01 this patent or the original patent UNITED STATES PATENTS Number Name Date 1,829,623 Wright Oct. 27, 1931 1,895,559 Straub et a1 Jan. 31, 1933 1,974,745 Klinkenstein Sept. 25, 1934 2,062,137 McKinney et al Nov. 24, 1936 2,111,395 Hartwick Mar. 15, 1938 2,168,212 Hicks Aug. 1, 1939 2,178,018 Hoimann Oct. 31, 1939 2,185,293 Copeman Jan. 2, 1940 2,186,014 Ellis Jan. 9, 1940 2,343,925 Pike Mar. 14, 1944 2,405,953 Hillery Aug. 20, 1946 FOREIGN PATENTS Number Country Date 498,024 .France Dec. 24, 1919 704,499 France May 20, 1931 877,582 France Dec. 10, 1942 ishes having a metallic appearance of great depth and brilliance which comprises blending (A), a relatively transparent pigmented composition. the pigment portion or which is selected from the group consisting oi. colloidal hydrous iron oxide and chromium tetrahydroxide; with (B) a transparent pigmented composition in which the,

pigment is substantially complementary in color to the pigment or (A) tinting the resulting blend with (C)- a colored pigmented composition and adding (D) a flake aluminum metal thereto.

13. The process 01' claim 12 in which the pigment (B) is a lake or dichloroisodibenzanthrone on barium rosinate.

14. The process oi claim 12 in which the pigment (B) is phthalocyanine blue.

15. The process 01 claim 12 in which the pigment (B) is phthalocyanine green.

16. The process of claim 12 in which the pigment (B) is vat thioindlgoid dyestuflf-indo maroon.

17. The process of claim 12 in which the aluminum flake is relatively coarse and about 40% of the total aluminum surface area is composed oi flakes with a diameter larger than 20 microns.

RALPH E. PIKE.

; Certificate of Correction.

Reissue No. 23,722 Ralph E. Pike 1 It is hereby certified that error appears in the rinted specification of the above numbered patent requirlng correction as fol ows:

Column 2, line 21, for must read most column 4, line 11, for avaialble read available line 20,v after non-chalking insert a comma; column 5, under Table 1, Note 2, fourth line thereof, for 10 microm'n read 10 microns in line 34, for Pigment read Pigments line 49, for strengtread stren th columns 7 and 8, Table 2, opposite (F) Brown, fifth and seventh co umns thereof, before 100, each occurrence, insert Total ;column 9, lines 63, 67, and 68, for complementary, each occurrence, read Complementary line 66, for conventional read Conventional line 69, for enamals read enamels column 11, line 7, for Pi ent 4 green read Pigment 4, green line 24, for perponderant rea preponderant ;line 58, for synethetic read synthetic ;column 13, line 9, for pigment l3 read pigment (B) and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Ofiice.

' Signed and sealed this 15th day of December, A. D. 1953.

ARTHUR W. CROCKER,

7 Assistant C'ommia'sioner of Patents.

October 13, 1953

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