US3414491A - Electrodeposition of nickel - Google Patents

Description

United States Patent 3,414,491 ELECTRODEPOSITION OF NICKEL Arthur H. Du Rose, Euclid, and William J. Pierce, Lyndhurst, Ohio, assignors, by mesne assignments, to Kewanee Oil Company, Bryn Mawr, Pa., a corporation of Delaware No Drawing. Filed Oct. 22, 1965, Ser. No. 502,603

11 Claims. (Cl. 204-49) ABSTRACT OF THE DISCLOSURE This invention comprises a nickel plating process and a nickel electroplating bath containing coumarin or certain derivatives thereof for providing leveling and other desirable characteristics. The tendency of the coumarin and related compounds to produce byproducts which cause disadvantageous results in the type of plating is avoided by also having present in the bath an acetylenic compound having the formula HCE CCH OC H OH wherein n equals 1-3.

This invention relates to electrodepositing nickel from an aqueous acidic nickel plating bath, relating more particularly to a process of and solutions for such electrodeposition utilizing coumarin or substituted coumarins together with certain acetylenic compounds.

Nickel electroplating baths containing coumarin or certain substituted coumarins are well known for their ability to provide a nickel deposit having superior leveling characteristics as well as producing a deposit which is semibright and reasonably uniform in appearance. Semibright deposits are not mirrorlike but are lustrous and are desirable as an undercoat for an outer layer of chromium or of a brighter nickel. However, such semibright nickel deposits cannot be dull or gray, or contain dark areas, or contain areas of much contrast, or they cannot be covered to produce a satisfactory over-all appearance when the outer layer is deposited. Also, such semibright nickel deposits must possess other characteristics in order to be acceptable commercially. For example, they must be ductile, free from excessive stress, and have good leveling characteristics; that is, the ability to cover minor imperfections while providing a surface which is much smoother than the surface of the basis metal.

The use of coumarin and substituted coumarins to produce a satisfactory nickel deposit has been considerably limited, however, because of the formation in the plating bath of acid breakdown products resulting from the reducing action of the electrolysis. The principal breakdown product is melilotic acid (o-hydroxy phenyl propionic acid) although trace amounts of other breakdown products are formed. While these other products have not been isolated or even identified definitely, they can cause considerable ditficulty in obtaining a satisfactory semibright deposit, tending to cause embrittle-ment and stressed deposits. The melilotic acid and other products also cause stressed deposits and more so as to its concentration increases; and causes the deposit to be gray rather than semibright, particularly in the lower current density portions of the cathode.

Generally speaking, an unagitated nickel plating bath containing about 0.2 g./l. of coumarin, or an air agitated bath containing about 0.1 g./l., will eventually build up a concentration of these products of about 4 g./l. Under normal circumstances, the maximum tolerance of the plating bath toward melilotic acid alone, without considering the other breakdown products for the moment, is about 1 g./l.

Efforts have been made to remove these undesirable breakdown products by treatment of the bath with activated carbon or other means of absorbing them. This procedure is employed only as often as utterly necessary since it not only requires time and effort but usually removes coumarin or other components from the bath which must be replaced and, of course, the bath cannot be operated during this procedure.

In order to avoid such treatments of the bath and the attendant adjustments which are always necessary, attempts have been made to reduce the concentration of the coumarin or coumarin derivatives. Accordingly, under normal circumstances, an unagitated solution containing coumarin must be operated with a concentration of coumarin of about 0.12 g./l., or when air agitated about 0.06 g./l. This very low concentration will assist in preventing excessive build-up of the breakdown products, but unfortunately in some cases it is too low a concentration of coumarin to provide the desired leveling and other results.

We have found that when a low concentration of a particular acetylenic compound is utilized in a solution containing the normal, or lower than normal concentration of coumarin or certain of its derivatives, the difiiculties normally associated with the breakdown products of coumarin can be avoided. In fact, such breakdown products appear to be of assistance when used with these acetylenic compounds for providing the desired semibright nickel deposit. The unsaturated compounds used are: HECCH (OC H ),,O-H, in which 11:1, 2, or 3. In particular the diethylene glycol monopropargyl ether is preferred and the concentration of this or the similar unsaturated co'rnpounds employed is 0.006 to 0.05 millimole per liter.

It should be noted particularly that these unsaturated compounds, when used in coumarin-containing baths, should be used in this range of concentration. Higher concentrations, while producing a bright deposit, also produce striation, brittleness, or other undesirable results. Incidentally, in this small concentration these acetylenic compounds, when used without the coumarin or substituted coumarins, have no appreciable effects on the bath and, in particular, will not cause any noticeable brightening of the deposit. On the other hand, when used without these acetylenics a concentration of about 0.2 g./l. of coumarin for an unagitated bath is needed in order to be effective in improving the leveling and ductility of the nickel deposit. But coumarin when used without these acetylenics produces too much melilotic acid and other products to remain effective. Also,.coumarin plus the acetylenics, both in the recommended concentrations, produces only mediocre results. Thus, it is unexpected that these acetylenics at such low concentration when used with a relatively high concentration of the coumarin compound in the presence of melilotic acid and other normally harmful breakdown products of the coumarin compound, produce the improvement of the present invention.

We have also found that when these acetylenic compounds are used in the concentration range mentioned, together with coumarin or substituted coumarins, a higher plating temperature may be used as well as a higher chlorine concentration in the bath. As illustrated in greater detail in the examples provided hereinafter, plating temperatures of 155 F. have been used, whereas normally in baths of the present type, F. is considered as the upper limit. Also, a nickel chloride content in the bath of about 7 02/ gal. has been used, whereas about 5 oz./ gal. would be normal for such baths.

Coumarin and substituted coumarins are, generally speaking, 1,2-benzopyrone compounds having a structure represented by the following formula, the customary numbering system showing positions of the substituents on the two rings being indicated:

Coumarin compounds which have been utilized successfully in plating baths of the present invention include, in addition to coumarin itself (unsubstituted 1,2-benzopyrone), 3-chlorocournarin, 3-bromocoumarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, 8-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and o-acetamido coumarin.

In addition to the acetylenic compounds referred to hereinbefore and an appropriate courmarin compound, chloral, bromal, or formaldehyde may be added to the bath if desired. These compounds appear to assist in producing a deposit which is more uniformly semibright and ductile and also in permitting the use of higher plating temperatures. In this connection, chloral, bromal, or formaldehyde have been added to coumarin-containing nickel plating baths previously in an effort to prolong as much as possible the interval between purification treatments (see US. 2,683,115); but such baths are not capable of producing the improved deposits of the present invention or of operating under the variety of plating conditions permitted by the present process especially at higher plating temperature and chloride ion concentration which, in turn, makes possible a higher current density at the cathode.

The following specific examples are illustrative of the present invention and are provided by way of illustration and not of limitation:

EXAMPLE I A commercially operated nickel plating bath had the following analysis:

Nickel sulfate oz./ga1 44 Nickel chloride oz./gal 6.7 Boric acid oz./gal 6.2 Coumarin g./l 0.08 Melilotic acid g./l 0.5 Formalin cc./l 0.5 pH 4.2 Zn p.p.m 10

This solution had been operated at 135 F., with air agitation. The deposit was semibright at 20-80 amp/sq. ft. but was not bright at 10-15 amp./ sq. ft. When operated without the Formalin or with very little Formalin, the deposit was dull at -20 amp/sq. ft. When the solution was operated at 150 F. the leveling was improved and the deposit was semibright at 30-80 amp/sq. ft. but was dull at 5-30 amp/sq. ft. This dull area could not be brightened enough by plating 0.3 mil of bright nickel over the deposit. The original solution was chilled and filtered to lower the boric acid content to four ounces per gallon and a deposit was taken at 155 F. but the deposit was not appreciably improved.

In order to provide satisfactory conductivity at higher current densities at the cathode it was desirable to keep the original nickel chloride content at 6.7 ounces per gallon and plating temperature at 150-155 F. In order to do this, the original solution was operated at 155 F. with 0.002 gram per liter (0.014 millimole per liter) of diethylene glycol monopropargyl ether added to the original bath. The deposit was bright-semibright and smooth and uniform. Also, the deposit was ductile and possessed good leveling characteristics. There was very little change in the deposit when the solution was operated at a pH of 3.5 instead of 4.2.

4 EXAMPLE 11 A typical Watts nickel solution containing 3-chlorocournar-in was operated to build up the reduction product melilotic acid to about 1 gram per liter. The chlorocoumarin was then adjusted to 0.10 gram per liter and the pH to 3.8.

A deposit was taken at F. and all of the cathode was slate gray except those portions having a current density over 60 amp/sq. ft. The addition of chloral at a concentration of 0.1 gram per liter improved the deposit in that it had a semibright appearance when plated at 135 F. but was dull in many areas when plated at 155 F. Also, the deposit was not ductile enough and tended to be brittle.

Diethyleneglycol monopropargyl ether was then added at a concentration of 0.002 gram per liter. The deposit was uniformly bright and was easily covered by bright nickel. Also, the leveling and ductility improved to the point of being commercially acceptable.

EXAMPLE III A previously operated sulfamate solution having ten ounces per gallon of nickel, 3 ounces per gallon of nickel chloride, 4.5 ounces per gallon of boric acid, 0.1 g am per liter of coumarin and 0.2 gram per liter of melilotic acid, was operated at F. at a pH of 4.2. In this particular test, bent cathodes were used; that is, cathodes having a V-shaped recess and sharp bends.

The bath as described above produced semibright nickel at 30-70 amp/sq. ft. but was gray at 11-25 amp/sq. ft. Also, the deposit was quite brittle. To this solution 0.002 gram per liter of diethylene glycol monopargyl ether was added. The deposit was semibright at 12-70 amp/sq. ft. and bright at 5-12 amp/sq. ft. The semibright area was more lustrous. The coating did not contain sharp areas of demarcation and was very satisfactory from the point of view of leveling. The addition of 0.2 cc./l. of Formalin and 0.1 gram per liter of choral produced very little change although the coating tended to have somewhat less sharp lines of demarcation and was more ductile.

EXAMPLE IV A Watts nickel solution containing 1 gram per liter of melilotic acid and 0.02 gram per liter of coumarin was electrolyzed for two hours with air agitation. This treatment is used to form small amounts of harmful impurities or breakdown products in addition to the melilotic acid. Coumarin was then added in a concentration of 0.012 gram per liter and the temperature and pH were adjusted to F. and 4.0 respectively. Straight, unbent panels were plated at an average of 30 amp./ sq. ft. This low current density provided a severe test because dullness and brittleness are more noticeable under these conditions than at normal current density values. A deposit of 1 mil in thickness was plated. The solution was divided into two cells. The results are stated in Table I below.

semibright deposit. Ductility 0.5; not stressed.

3 0.2 ca/l. Formalin added.

Uniform semibright. Ductility 0.5. Not stressed.

semibright but ductility 0.02-0.035 and high stress. 0.2 cell. Formalin added.

Deposit almost bright. Duetility 0.5; hi h stress.

4 0.05 g./l. chloral added. De- 0.05 g./l. chloral a ded. De-

posit similar to 3A. posit similar to 313. 0.02 g./l.

more diethylene glycol monopropargyl ether added. Deposit similar but some striations.

A ductility of 0.05 is most unsatisfactory. A ductility of 0.5 would be satisfactory. In this experiment the additions were dissolved in the bath cumulatively; that is, di-

COMPARATIVE EXAMPLE I To a Watts solution operated at 140 F., 40 amp/sq. ft., pH of 4.0, and with air agitation, 0.12 g./l. of coumarin was added. The solution contained no melilotic acid during all of this particular experiment. The deposit was semibright with a tendency toward grayness at 7-8 amp/sq. ft. The ductility was satisfactory. Diethylene glycol monopropargyl ether was then added to a concentration of 0.002 g./l. The deposit was slightly more lustrous with the 7-8 amp/sq. ft. area being semibright. The ductility was also satisfactory. The diethylene glycol monopropargyl ether concentration was increased to 0.02 g./l. Now the deposit had bright and semibright areas with striations at the line of demarcation between semibright and bright areas. The ductility varied from 0.14 to 0.45, i.e., was only satisfactory at times. While this "was a brighter deposit than when 0.002 g./l. of diethylene glycol monopropargyl ether had been used, it was not commercially acceptable.

From a study of the foregoing examples, it will be noted that the use of coumarin or certain substituted coumarins required concentrations of 0.12 gram per liter or more in order to produce a deposit having a semibright appearance. However, such deposits were often nonuniform or even dull gray in areas, especially areas of low current density. Attempts to improve the situation by adding chloral, bromal, or formaldehyde, or combinations of these additives did not produce the desired results when a high temperature was used. Sometimes the deposit was made brighter or more uniform but it would also be stressed too much or at times have unsatisfactory leveling characteristics. Use of a higher plating temperature was desirable in that the current could be increased without an increase in voltage, but also failed to produce a wholly satisfactory deposit. The same could be said for increasing the chloride content and, of course, for increasing both the chloride content and the plating temperature.

It will also be noted from a consideration of Comparative Example I, that the addition of the acetylenic compounds of the present invention did not produce noticeably better results in the absence of melilotic acid or other breakdown products of the coumarin compounds. In this connection, the bath of this example was especially prepared and the experiment carefully conducted inasmuch as commercial baths build up such breakdown products of coumarin very readily, especially melilotic acid. Thus, the additives of the present invention become necessary in practical operating baths; and, as noted hereinbefore, the use of diethylene glycol monopropargyl ether or the other acetylenic compounds hereof in the concentrations recommended will produce a commercially satisfactory deposit when melilotic acid or other breakdown products are present in the bath, producing a deposit which is not only substantially uniformly semibright but possesses the necessary ductility and leveling characteristics to be wholly acceptable commercially.

The invention claimed is:

1. In a process for electrodepositing a ductile semibright nickel substantially smoother than the basis metal to which it is applied utilizing an aqueous acid electroplating bath containing at least one soluble nickel compound, the improvement consisting of conducting such electrodeposition from a bath containing a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, 8-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and G-acetamido coumarin, operating said bath so as to produce therein reduction products of said coumarin, and including in said bath in the presence of said reduction products 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula HCECCH (OC H OH wherein n=1, 2, or 3.

2. In a process for electrodepositing a ductile semibright nickel substantially smoother than the basis metal to which it is applied utilizing an aqueous acid electroplating bath containing at least one soluble nickel compound, the improvement consisting of conducting such electrodeposition from a bath containing a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8- dimethyl coumarin, 8-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and 6-acetamido coumarin, operating said bath so as to produce therein reduction products of said coumarin compound, and including in said bath in the presence of said reduction products 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula wherein n=1, 2, or 3 and also including in said bath a member of the group consisting of chloral, bromal, and formaldehyde.

3. In a process for electrodepositing a ductile semibright nickel substantially smoother than the basis metal to which it is applied utilizing an aqueous acid electroplating bath containing at least one soluble nickel compound, the improvement consisting of conducting such electrodeposition from a bath containing a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3- chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 7- hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, S-methoxy coumarin, 7-ethoxy coumarin, 6- propargoxy coumarin, and 6-acetamido coumarin, operating said bath at a temperature of F. to F. for such a time as to produce therein reduction products of said coumarin compound, and including in said bath in the presence of said reduction products 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula HCEC-CH (OC H ),,OH wherein ni=l, 2, or 3.

4. In a process for electrodepositing a ductile semibright nickel substantially smoother than the basis metal to which it is applied utilizing an aqueous acid electroplating bath containing 30 to 60 ounces per gallon of nickel sulfate and 6 to 10 ounces per gallon of nickel chloride, the improvement consisting of conducting such electrodeposition from a bath containing a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8- dimethyl coumarin, 8-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and 6-acetamido coumarin, operating said bath so as to produce therein reduction products of said coumarin compound, and including in said bath in the presence of said reduction products 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula wherein n=1, 2, or 3.

5. In a process for electrodepositing a ductile semibright nickel substantially smoother than the basis metal to which it is applied utilizing an aqueous acid electroplating bath containing at least one soluble nickel compound, the improvement consisting of conducting such electrodeposition from a bath containing a coumarin com pound selected from the group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8- dimethyl coumarin, 8-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and G-acetamido coumarin, operating said bath for such a time as to produce at least 0.5 gram per liter of melilotic acid in said bath, and including therein 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula HCECCH2(OC2H4)I1OH wherein 11:1, 2, or 3.

6. In a process for electrodepositing a ductile semibright nickel substantially smoother than the basis metal to which it is applied utilizing an aqueous acid electroplating bath containing at least one soluble nickel compound, the improvement consisting of conducting such electrodeposition from a bath containing a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocournarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, -chlorocoumarin, 4,8- dimethyl coumarin, S-methoxy coumarin, 7ethoxy coumarin, 6-propargoxy coumarin, and -acetamido coumarin, operating said bath at a temperature of 140 F. to 155 F. for such a time as to produce at least 0.5 gram per liter of melilotic acid in said bath, and including in said bath in the presence of said melilotic acid 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula HCECCH (OC H ),,OH

wherein 11:1, 2, or 3, and also including in said bath a member of the group consisting of chloral, bromal, and 1 formaldehyde.

7. In a process for electrodepositing a ductile semibright nickel substantially smoother than the basis metal to which it is applied utilizing an aqueous acid electroplating bath containing 30 to 60 ounces per gallon of pyrone, 3-chlorocournarin, 3-bromocoumarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, S-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and 6-acetamido coumarin, operating said bath at a plating temperature of 140 F. to 155 F. for such a time as to produce at least 0.5 gram per liter of melilotic acid in said bath, and including in said bath in the presence of said melilotic acid a compound having a structure represented by the formula HCECCH (OC H ),,OH wherein n:l, 2, or 3.

8. A nickel electroplating bath adapted to produce a ductile sernibright nickel deposit substantially smoother than the basis metal to which it is applied comprising an aqueous solution of at least one nickel salt and in which there is dissolved at least 0.5 gram per liter of a coumarin compound selected from the group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, 8-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and 6-acetamido coumarin, at least 0.5 gram per liter of melilotic acid, and 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula wherein 11:1, 2, or 3.

9. A nickel electroplating bath adapted to produce a ductile semibright nickel deposit substantially smoother than the basis metal to which it is applied comprising an aqueous solution of at least one nickel salt and in which there is dissolved at least 0.5 gram per liter of a coumarin compound selected from the group consisting of 1,2-

benzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3- acetylcoumarin, 6-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, 8-methoxy coumarin, 7- ethoxy coumarin, 6-propargoxy coumarin, and 6-acetamido courmarin, at least 0.5 gram per liter of melilotic acid, and 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula wherein 11:1, 2, or 3, and at least 0.01 gram per liter of a member of the group consisting of chloral, bromal, and a 40% aqueous solution of formaldehyde.

10. A nickel electroplating bath adapted to produce a ductile semibright nickel deposit substantially smoother than the basis metal to which it is applied, comprising an aqueous solution containing 30 to 60 ounces per gallon of nickel sulfate and 6 to 10 ounces per gallon of nickel chloride in which there is dissolved at least 0.5 gram per liter of a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 6-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, S-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and 6-acetamido coumarin, at least 0.5 gram per liter of melilotic acid, and 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula HCECCH (CH H ),,OH wherein 11:1, 2, or 3.

11. A nickel electroplating bath adapted to produce a ductile semibright nickel deposit substantially smoother than the basis metal to which it is applied comprising an aqueous solution containing 30 to 60 ounces per gallon of nickel sulfate and 6 to 10 ounces per gallon of nickel chloride and in which there is dissolved at least 0.5 gram per liter of a coumarin compound selected from a group consisting of 1,2-bcnzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 6-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dirnethyl coumarin, 8- methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and 6-acetamido coumarin, at least 0.5 gram per liter of melilotic acid, and 0.006 to 0.5 millimole per liter of a compound having a structure represented by the formula HCECCH (OC H OH wherein n:l, 2, or 3, and at least 0.01 gram per liter of amember of the group consisting of chloral, bromal, and a 40% aqueous solution of formaldehyde.

References Cited UNITED STATES PATENTS 2,635,076 4/1953 Du Rose 20449 2,712,522 7/ 1955 Kardos et al. 20449 2,782,153 2/1957 Du Rose et al. 20449 2,818,376 12/1957 Foulke et al. 204-49 2,900,707 8/1959 Brown 20449 XR 2,986,501 5/1961 Martin 20449 3,140,988 7/1964 Clauss et al. 20449 3,305,462 2/1967 Ostrow et al. 204-49 FOREIGN PATENTS 542,292 11/1955 Belgium.

632,773 12/1961 Canada.

269,880 6/ 1964 Netherlands.

HOWARD S. WILLIAMS, Primary Examiner.

G. KAPLAN, Assistant Examiner,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,414,491 December 3, 1968 Arthur H. Du Rose et'al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 30, "HEC-CH (OC H OH" should read HCEC-CH (OC H OH Column 4, line 49, "0.012" should read 0.12 Column 7, lines 49 and 65, and column 8, lines 18 and 33, "0.5", each occurrence, should read 0.06

Signed and sealed this 10th day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, IR.