US3591352A

US3591352A - Processes for selectively plating one component of multi-component plastic articles and articles produced thereby

Info

Publication number: US3591352A
Authority: US
Inventors: Peter D Kennedy; Harold M Goldstein
Original assignee: Nibot Corp
Current assignee: Precise TMP Inc; Nibot Corp
Priority date: 1968-12-04
Filing date: 1968-12-04
Publication date: 1971-07-06
Anticipated expiration: 1988-07-06

Abstract

THERE ARE DICLOSED HEREIN PROCESSES FOR PRODUCING MULTI-COMPONENT PLASTIC WORKPIECES IN WHICH AT LEAST A FIRST COMPONENT THEREOF HAS A PLATED METAL COATING THEREON, AND WORKPIECES PRODUCED BY SUCH PROCESSES. THESE PROCESSES GENERALLY COMPRISE PROVIDING A STRIKE SOLUTION, PROVIDING A MULTI-COMPONENT WORKPIECE INCLUDING A FIRST COMPONENT FORMED OF A FIRST PLASTIC MATERIAL ON WHICH A METAL IS DEPOSITED UPON APPLICATION OF THE STRIKE SOLUTION THERETO AND AT LEAST A SECOND COMPONENT FORMED OF A SECOND PLASTIC MATERIAL ON WHICH NO METAL IS DEPOSITED UPON APPLICATION OF THE STRIKE SOLUTION THERETO, APPLYING THE STRIKE SOLUTION TO THE WORKPIECE TO DEPOSIT A METAL STRIKE ON THE FIRST COMPONENT WITHOUT DEPOSITING A METAL STRIKE ON THE SECOND COMPONENT, AND PLATING A LAYER OF PLATING METAL OVER THE METAL STRIKE TO PROVIDE A PLATED METAL COATING ON THE FIRST COMPONENT WHILE NO METAL IS PLATED ON THE SECOND COMPONENT.

Description

July 6, 1971 p, KENNEDY ETAL 3,591,352

PROCESSES FOR SELECTIVELY PLATING ONE COMPONENT OF MULTI-COMPONENT PLASTIC ARTICLES AND ARTICLES PRODUCED THEREBY Filed Dec. 4, 1968 FIG./

IN VEN TORS PETER D. KENNEDY HAROLD M. GOLDSTE/N MW /D a I 667$ ATTYS.

United States Patent Filed Dec. 4, 1968, Ser. No. 780,984 Int. Cl. C23b 5/48, 5/60; B44d 1/18 US. Cl. 29-195 41 Claims ABSTRACT OF THE DISCLOSURE There are disclosed herein processes for producing multi-component plastic workpieces in which at least a first component thereof has a plated metal coating thereon, and workpieces produced by such processes. These processes generally comprise providing a strike solution, providing a multi-cornponent workpiece including a first component formed of a first plastic material on which a metal is deposited upon application of the strike solution thereto and at least a second component formed of a second plastic material on which no metal is deposited upon application of the strike solution thereto, applying the strike solution to the workpiece to deposit a metal strike on the first component without depositing a metal strike on the second component, and plating a layer of plating metal over the metal strike to provide a plated metal coating on the first component While no metal is plated on the second component.

The present invention is directed to processes for producing multi-component plastic workpieces, the components thereof being composed of different plastic materials whereby a deposit of metal strike is applied to at least one of the component parts followed by depositing a layer of plating metal thereover without depositing any metal on the remaining components, and workpieces produced by such processes.

It is a principal object of this invention to provide a process for producing a multi-component plastic workpiece having at least a first component formed of a first plastic material and at least a second component formed of a second plastic material joined thereto wherein a layer of plating metal is plated on the first component While no metal is plated to the second component thereof.

Generally, the process comprises providing a strike solution, providing a multi-component workpiece including at least a first component formed of a first plastic material on which a metal strike is deposited upon application of the strike solution threto and at least a second component formed of a second plastic material on which no metal strike is deposited upon application of the strike solution thereto, applying the strike solution to the workpiece to deposit a metal strike on the first component without depositing a metal strike on he second component, and plating a layer of plating metal over the metal strike to provide a plated metal coating on the first component while no metal is plated on the second component.

Another object of this invention is to provide a process for producing a multi-component plastic workpiece of the type set forth wherein the strike solution consists essentially of an aqueous solution containing strike metal ions and an electroless reducing agent therefor.

A further object of this invention is to provide a process for producing multi-com'ponent plastic workpieces of the type set forth wherein the individual components of the workpiece are joined together by mechanical interlocking, or by molding the components together.

A still further object of this invention is to provide a process for producing multi-component plastic workpieces of the type set forth wherein each of the plastic materials is a synthetic organic plastic resin.

Yet another object of this invention is to provide a process for producing multi-comp-onent plastic workpieces wherein the first plastic material is selected from polypropylene resins and acrylo-nitrile-butadiene-styrene copolymer resins; and the second plastic material is selected from polycarbonate resins, modified phenylene oxide resins, polyphenylene oxide resins, polyvinyl chloride resins and stereo-regular polyolefin resins.

A further object of this invention is to provide a process for producing multi-component plastic workpieces of the type set forth wherein the plating metal is deposited on the metal strike by contacting the workpiece with an electroplating bath.

Yet another object of this invention is to provide a process for producing multi-component plastic workpieces of the type set forth wherein the plating metal is deposited on the metal strike by contacting the workpiece with an electroless metallizing bath consisting essentially of an aqueous solution containing electroless metal ions and an electroless reducing agent therefor.

A further object of this invention is to provide a multicomponent plastic workpiece comprising at least a first component formed of a first plastic material and at least a second component formed of a second plastic material joined thereto, the first component carrying a layer of plated metal, being deposited thereon by simultaneously exposing to a plating bath both the first component and the second component after joinder thereof.

Still another object is to provide a multi-component plastic workpiece of the type set forth wherein the first component carries an intermediate deposit of metal strike thereon over which is plated a layer of plating metal.

Further features of the invention pertain to the particular arrangements of the steps of the processes and the plastic materials utilized therein, whereby the above outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which:

FIG. 1 is a top plan view of a multi-component plastic coaster provided with a layer of plated metal on the base portion thereof and embodying the present invention;

FIG. 2 is a view in vertical section along line 2-2 of FIG. 1; and

FIG. 3 is a view in cross-section of a two-component workpiece wherein the components are mechanically joined by a pin.

Heretofore, where it has been desirable to plate a metal coating to the surface of only a portion of a plastic material, it has been necessary to seal or cover that portion of the article which is to remain free of the metal lating and expose only the surface of that portion to be plated to the pro-plating and plating operations. To this end, sealers formed of masking tape or stripping lacquers and the like have been employed to shield that portion which is to remain free of the metal plate. Alternatively, the article may be produced as separate components, plating that component which is to carry the metal plate in a separate operation, and then joining or assembling the plated part with the unplated part or parts. The latter technique has had particular applicability with respect to those plastic articles which consist of two or more different plastic materials. However, these procedures entail a number of steps and are, therefore, not only cumbersome o and time consuming, but economically impractical from a manufacturing point of view.

In accordance with the present invention, there is provided a multi-component workpiece in which at least a first component thereof formed of a first plastic material is to have a plated metal coating thereon and at least a second component thereof formed of a second plastic material which is to have no metal coating plated thereon, said components being joined together to form a unitary article or workpiece. The individual components may be joined together by mechanical interlocking, or by molding one component to the other, such as the procedure known as double-shot molding, the present invention being essentially independent of the manner in which the components are so united. The different plastic materials utilized are selected such that the component which is to carry the plated metal is formed of a material which Will accept an initial deposit of a metal strike when contacted with a strike solution whereas the remaining components are selected from plastic materials which will not accept the deposit of the metal strike when simultaneously exposed to a strike solution.

The workpieces described herein are referred to as plastic workpieces, and while the term plastic may generally refer to any number of combinations or organic or inorganic substances and the processes of the present invention may be utilized in producing metal plated workpieces formed of such substances, the term as used herein has particular reference to synthetic organic plastic resins. More specifically, the preferred plastic materials which are to be plated are selected from the polypropylene resins such as those sold under the trademark Oleplate, and the acrylonitrile-butadiene-stryrene copolymer resins such as those sold under the trademark Marbon EP- 3510; and the plastic materials which are to remain unplated are selected from the polycarbonate resins such as those sold under the trademark Lexan, the modified phenylene oxide resins such as those sold under the trademark Noryl, the polyphenylene oxide resins such as those sold under the trademark PPO, the polyvinyl chloride resins such as those sold under the trademark Vinyl 7008 and Vinyl 84l-N, and the polyolefin resins such as the stereo-regular polyolefin sold under the trademark TPX.

To produce workpieces in accordance with the present invention, the workpiece is first thoroughly cleaned using any one of several well-known cleaning methods, after which the surface of the workpiece is conditioned in accordance with well-known conditioning procedures in order to prepare the surface thereof for receiving the initial deposit of metal strike. The surface of the workpiece having been cleaned and conditioned, it is then contacted with a strike solution which consists of an aqueous solution containing electroless metal ions and an electroless reducing agent therefor, whereby the metal ions are reduced and deposited on the surface of the component formed of a plastic material which will accept the strike deposit. The metals which may be used as the metal strike include any metals which will adhere to the surface and render the plastic surface catalytic, such as cooper, nickel and cobalt. The workpiece may then be plated by an electroplating system utilizing the metal to be plated thereon. Alternatively and if desired, the plating may be accomplished by contacting the workpiece with an electroless metallizing bath which consists of an aqueous solution containing electroless metal ions and an electroless reducing agent therefor. A suitable electroless metallizing bath of this type is, for example, a conventional chemical nickel plating bath of the nickel cation-hypophosphite anion type. In either event, a layer of plating metal is plated over the metal strike deposit forming a multi-component plastic workpiece having a layer of plating metal plated on the surface of only that component formed of a plastic material which will accept metal deposits while the remaining components are substantially free of any metal deposits.

The conditioning procedure is necessary in order to prepare the surface of the plastic material which is to receive the metal strike deposit. The workpiece is first contacted with a conditioner comprising a highly concentrated acid bath in order to clean and etch the surface thereof to promote bonding between the deposit of metal strike and the plastic surface. A suitable acid bath conditioner consists of a highly concentrated solution of chromic acid and sulfuric acid, although other acids such as nitric acid, may similarly be utilized. The workpiece is then rinsed in water and contacted with a neutralizer generally consisting of an alkaline carbonate solution in order to neutralize any acid which remains on the surface of the workpiece. Finally the workpiece is again rinsed in water and then contacted with an actuator consisting of an aqueous solution containing the salt of a catalytic metal such as palladium, platinum, gold or silver.

The workpiece having been cleaned and conditioned as set forth, it is now contacted with a strike solution. The strike solution generally consists of an aqueous solution containing metal strike ions and a reducing agent therefor. The metal strike ions are reduced by the reducing agent to deposit on the surface of the plastic material a deposit of metal strike. The deposit will only form on the surface of the plastic material which will accept a metal deposit leaving the remaining components of the workpiece free of any metal deposits. These strike metal deposits will then act as a substrate for the plating metal to be plated thereon in a plating operation.

The workpiece having the deposit of metal strike on the surface of that plastic material which will accept the deposit of metal thereon may then be plated with a layer of plating metal. The plating may be accomplished by standard electroplating procedures or by contacting the workpiece with an electroless metallizing bath consisting of an aqueous solution of an electroless metal salt and an electroless reducing agent therefor. In either event, a layer of plating metal is plated over the metal strike deposit, whereby the workpiece includes a first component formed of a first plastic material having a layer of plated metal covering the surface thereof, and at least a second component formed of a second plastic material which has no deposit of any metal thereon.

Although the processes of this invention may be practiced upon a multi-component workpiece, the components of which have been joined together by mechanical interlocking or other such means, these processes are particularly beneficial when practiced upon a multi-component workpiece which has been produced by a double-shot molding operation, since the number of processing steps are thereby reduced, simplifying the manufacture and reducing the cost of producing such articles.

The nature of the metal plated multi-component plastic workpieces produced in accordance with this invention will be more clearly understood by reference to the illustrative drawings. FIG. 1 is a top plan view of a household coaster 10 having the base 11 molded of a first plastic material and an inlay 12 molded of a second plastic material. The base 11 and the inlay 12 are produced by a double-shot injection molding operation wherein the base 11 is formed of a first plastic material and molded by a primary shot of the injection molding machine and subsequently transferred to a second mold where the inlay 12, formed of a second plastic material is molded to the base 11 by a second shot of the injection molding machine to provide a coaster formed of two different plastic components molded together. The base 11 is formed of a plastic material which will accept a deposit of metal strike whe ncontacted with a strike solution whereas the inlay 12 is formed of a plastic material which will not accept a deposit of metal strike when similarly contacted with a strike solution. The

coaster as molded is then cleaned, conditioned and finally contacted with a strike solution. As a result of the foregoing treatment, there is deposited only on the surface of the base 11 a deposit of strike metal 13 (FIG. 2.). The coaster 10 is then plated by an electroplating operation, or by contact with an electroless metallizing bath to provide a coating of plated metal 14 over the metal strike deposit 13.

FIG. 3 is a cross-sectional view of a two-component workpiece joined together by mechanical means. The first section 15 is formed of a plastic material which will accept a metal strike deposit when contacted with a strike solution whereas the second section 16 is formed of a plastic material which will not accept a deposit of metal strike when similarly contacted with a strike solution. The two sections are joined together by a pin 17, having a truncated cone portion 18 adjacent one end thereof and a head 19 at the other end thereof. The first and

second sections

15 and 16 are molded such that each has a fitment for receiving the corresponding section of the pin 17 in the sections to be joined together. As can be seen in FIG. 3 section 15 is provided with a channel 21 for receiving a portion of the stem 22 of the pin 17. The second section 16- is similarly provided with a channel 23 which mates with channel 21 of section 15 to receive the remaining portion of the stem 22 of the pin 17 and a truncated cone recess 24 adapted to receive the truncated cone portion 18 of the pin 17. Where the two

sections

15 and 16 have been mated, the pin 17 is inserted into the corresponding

channels

21 and 23 such that the truncated cone portion 18 of the pin 17 is fitted within the truncated cone recess 24. A hot plate or rod (not shown) then presses against the opposing end of the pin forming the head 19 which is fitted in a head recess such that the surface of section 15 remains essentially fiat. The head 19 and the truncated cone portion 18 of the pin 17 serve to lock the

sections

15 and 16 together.

After the

sections

15 and 16 have been joined together as illustrated, the workpiece may then be subjected to the processes provided by this invention whereby a strike metal is deposited on the surface of section 15 and plated metal is coated thereover, while section 16 receives no deposit or coating of any metal.

A typical example of the processes described herein for producing plated metal workpieces as illustrated in FIG. 1 through 3 is described in the following example:

EXAMPLE 1 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2 of the illustrative drawings that was produced by the use of a ram screw injection molding machine having a first mold in which the base or first component of the coaster was produced in a primary shot, and having a second mold in which the inlay or second component of the coaster was produced in a secondary shot of the injection molding machine. The base was formed of a polypropylene resin sold under the trademark Oleplate previously mentioned, while the inlay was formed of a modified phenylene oxide resin sold under the trademark Noryl previously mentioned.

Step 2 ladium chloride, for a period of one minute and rinsed in water once again.

Step 3 The conditioned coaster was then immersed in a strike solution in the form of an electroless metallizing bath comprising an aqueous solution containing the following ingredients and used under the conditions indicated:

Copper sulfate20 grams per liter Triethanolamine-1OO grams per liter Formaldehyde solution )20 milliliters per liter pH12.5

Temperature-25 C.

After immersion in the foregoing electroless metallizing bath for a period of about 30 minutes, a metal strike in the form of a continuous electrically-conductive deposit of copper metal was formed on the surface of the first component of polypropylene resin, i.e., upon the surface of the base 11, whereas no metal strike or deposit of copper metal was formed on the surface of the second component of modified phenylene oxide resin, i.e., upon the surface of the inlay 12.

Step 4 The copper-plated coaster was next electroplated with nickel metal by utilizing a nickel electroplating bath consisting of the following ingredients:

Nickel sulfate240 grams per liter Nickel chloridegrams per liter Boric acid-30 grams per liter The copper-plated coaster was connected as a cathode in a standard electroplating system utilizing the above bath at a temperature of C., a current density of 30 amps per square foot being established on the coaster. After a period of 30 minutes, a plated metal coating of nickel metal was electroplated over the copper metal strike deposit such that only the base portion of the coaster was plated while the inlay portion remained free of any nickel metal deposit.

The first and second components of the two-component workpiece in the form of a coaster as described in Step 1 of Example 1 may be formed of various other types of plastic materials, and processed in accordance with Steps 2, 3 and 4 of Example 1 to produce thereby a two-component coaster in which the first component thereof has a deposit of metal strike and a layer of electroplated metal thereover and in which the second component thereof has no deposit of metal strike or electroplated metal. The following examples illustrate other plastic materials of which the base or first component of the coaster may be formed which will accept a deposit of strike metal on the surface thereof and similarly, other plastic materials of which the inlay or second component of the coaster may be formed which will not accept a deposit of metal strike on the surface thereof.

EXAMPLE 2 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of a polypropylene resin sold under the trademark Oleplate, and having the second component or inlay thereof formed of a polycarbonate resin sold under the trademark Lexan.

Steps 2, 3 and 4 of Example 1 were then repeated utilizing the two-component plastic coaster as described above, whereby to provide first a copper metal strike on the base which was thereafter electroplated with nickel plating metal, the inlay receiving no deposit of strike metal or electroplated metal.

7 EXAMPLE 3 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of a polypropylene resin sold under the trademark Oleplate, and having a second component or inlay thereof formed of a polyphenylene oxide resin sold under the trademark PPO.

Steps 2, 3 and 4 of Example 1 were then repeated utilizing the two-component plastic coaster as described above, whereby to provide first a copper metal strike on the base which was thereafter electroplated with nickel plating metal, the inlay receiving no deposit of metal strike or electroplated metal.

EXAMPLE 4 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of a polypropylene resin sold under the trademark Oleplate, and having a second component or inlay thereof formed of a polyvinyl chloride resin sold under the trademark Vinyl 841-N.

EXAMPLE 5 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of a polypropylene resin sold under the trademark Oleplate and having the second component or inlay thereof formed of a polyvinyl chloride resin sold under the trademark Vinyl 7008.

EXAMPLE 6 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of a polypropylene resin sold under the trademark Oleplate, and having a second component or inlay thereof formed of a stereo-regular polyolefin and specifically a 4- methylpentene-l polymer sold under the trademark TPX'!7 Steps 2, 3 and 4 of Example 1 were then repeated utilizing the two-component plastic coaster as described above, whereby to provide first a copper metal strike on the base which was thereafter electroplated with nickel plating metal, the inlay receiving no deposit of strike metal or electroplated metal.

EXAMPLE 7 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of an acrylonitrile-butadiene-styrene copolymer resin sold under the trademark Marbon EP-3510, and having a second component or inlay thereof formed of a modified phenylene oxide resin sold under the trademark Noryl.

EXAMPLE 8 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of an acrylonitrile-butadiene-styrene copolymer resin sold under the trademark Marbon EP3510, and having a second component or inlay thereof formed of a polycarbonate resin sold under the trademark Lexan.

Steps 2, 3 and 4 of Example 1 were then repeated utilizing the two-component plastic coaster as described above, whereby to provide first a copper metal strike on the base which was thereafter electroplated with nickel plating metal, the inlay receiving no deposit of strike metal of electroplated metal.

" EXAMPLE 9 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of an acrylonitrile-butadienestyrene copolymer resin sold under the trademark Marbon EP3510 and having a second component or inlay thereof formed of a polyphenylene oxide resin sold under the trademark PPO.

EXAMPLE 10 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of an acrylonitrile-butadiene-styrene copolymer resin sold under the trademark Marbon EP-3510 and having a second component or inlay thereof formed of a polyvinyl chloride resin sold under the trademark Vinyl 841-N.

EXAMPLE 11 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of an acrylonitrile-butadiene-styrene copolymer resin sold under the trademark Marbon EP-3510 and having a second component or inlay thereof formed of the polyvinyl chloride resin sold under the trademark Vinyl 7008.

EXAMPLE 12 Step 1 There was provided a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2, the coaster having a first component or base thereof formed of an acrylonitrile-butadiene-styrene copolymer resin sold under the trademark Marbon -EP-3510, and having a second component or inlay thereof formed of a stereoregular polyolefin, 4-methylpentene-1 sold under the trademark TPX.

The foregoing examples illustrate the various combinations of plastic materials of which the individual components of a multi-component workpiece may be formed such that when the workpiece is treated as described in Steps 2, 3 and 4 of Example 1, there is produced a multicomponent workpiece having a first component formed of a first plastic material which has a deposit of strike metal on the surface thereof and a layer of plated metal thereover, and having a second component thereof formed of a second plastic material which has no deposit of strike metal or electroplated metal thereon.

In Step 2 of Examples 1 through 12, above, it has been found that a preferred conditioner is that which is sold under the trade designation Enplate Conditioner 470 (specific gravity: 1.550). Other combinations of time and temperature may be utilized in the place of the 5 minutes at 80 F. given in Example 1; for example, the same materials may be treated for 4 minutes at 100 F. for 30 seconds at 120 F.

The preferred neutralizer in Step 2 is that sold under the trade designation Enplate AD-480. Although it is preferred that the neutralizing step be conducted for a substantial period of time such as the 30 seconds specified in Example 1, it has been found that satisfactory results can be obtained with an immersion time as short as seconds.

Finally, it is pointed out that the preferred activator is that sold under the trade designation Enplate 440.

In each of the above example, the strike solution of Step 3 comprised an electroless metallizing bath containing an aqueous solution of strike metal ions in the form of copper ions and formaldehyde as the reducing agent therefor, whereby the strike metal deposit was a deposit of copper metal. It will be understood that a number of metallizing processes of the electroless type may be effectively utilized to produce a deposit of strike metal on the surface of a first component of a multi-component workpiece, while no deposit of strike metal is produced on the surface of a, second component thereof. In addition to the electroless processes described in Examples 1 through 12, electroless nickel processes and electroless cobalt processes may similarly be utilized. The following examples illustrate the use of such other metallizing processes of the electroless type which are useful as strike solutions in forming a deposit of strike metal on the surface of the first component of a multi-component workpiece without at the same time depositing any strike metal on the surface of the second component thereof.

EXAMPLE 13 Steps 1 and 2 of Example 1 were repeated to produce a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2 having a first component or base formed of a polypropylene resin sold under the trademark Oleplate and a second component or inlay formed of a modified phenylene oxide resin sold under the trademark Noryl, treated with a conditioner, a neutralizer and an activator in accordance with Step 2 of Example 1.

Step 3 The two-component coaster was then immersed in a strike solution in the form of an electroless metallizing bath comprising an aqueous solution containing the following ingredients and used under the conditions indicated:

Nickel sulfate0.08 mole/liter Sodium hypophosphite0.23 mole/liter Lactic anion0.30 mole/ liter Propionic anion-0.03 mole/liter Lead ion1 part per million After immersion in the foregoing electroless metallizing bath for a period of about 30 minutes, a strike metal deposit in the form of a continuous electrically-conductive deposit of nickel metal was formed on the surface of the first component of polypropylene resin, i.e. upon the surface of the base 11, whereas no strike metal or deposit of nickel metal was formed on the surface of the second component of modified phenylene oxide resin, i.e. upon the surface of the inlay 12.

Step 4 of Example 1, was then repeated utilizing the two-component coaster as described above whereby to provide first a nickel metal strike on the base which was thereafter electroplated with nickel plating metal, the inlay receiving no deposit of strike metal or electroplated metal.

In the foregoing example the absolute concentration of hypophosphite in the bath expressed in mole/liter may vary within the range from about 0.15 to about 1.20 and the ratio betWen the nickel cations and hypophosphite anions in the bath expressed in molar concentrations may vary within the range from about 0.25 to about 1.60. The lactic anion serves as a complexing agent and may be derived from lactic acid or salts thereof, the absolute concentration of lactic ions in the bath expressed in mole/ liter being within the range from about 0.25 to 0.60. The bath also includes an exalting additive, namely, the propionic anion, which has a concentration in the bath expressed in mole/liter in the range from about 0.025 to 0.060. Other exalting additives may be used in place of the propionic anion, the exalting additive being selected from the group consisting of simple short chain saturated aliphatic monocarboxylic acids, including three to five carbon atoms and salts thereof. Details of the composition of such a bath and the method of using same are set forth in US. Pat. 2,822,294, granted on Feb. 4, 1958 to Gregoire Gutzeit, Paul Talrney and Warren G. Lee.

The lead content of the nickel plating bath of Example 13 performs the function of stabilizing the bath during the plating operation. Other types of stabilizers and other amounts of such stabilizers may be advantageously utilized in connection With the present invention, suitable such stabilizers being disclosed in U.S. Pat. No. 2,762,723, granted on Sept. 11, 1956 to Paul Talmey and Gregoire Gutzeit.

EXAMPLE 14 Steps 1 and 2 of Example 1 were repeated to produce a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2 having a first component or base formed of a polypropylene resin sold under the trademark Oleplate and a second component or inlay formed of a modified phenylene oxide resin sold under the trademark Noryl, treated with a conditioner, a neutralizer and an activator in accordance with Step 2 of Example 1.

1 1 Cobalt chloride-50 grams/ liter Rochelle salt350 grams/ liter Ammonium chloridel grams/ liter Sodium hypophosphite35 grams/ liter pH9.0 Temperature98 C.

After immersion in the foregoing electroless metallizing bath for a period of about 30 minutes, a strike metal in the form of a continuous electrically-conductive deposit of cobalt metal was formed on the surface of the first component of polypropylene resin, i.e., upon the surface of the base, whereas no strike metal or deposit of cobalt metal was formed on the surface of the second component of modified phenylene oxide resin, i.e., upon the surface of the inlay 12.

Step 4 of Example 1 was then repeated utilizing the two-component coaster as described above whereby to provide first a cobalt metal strike on the base which was thereafter electroplated with nickel plating metal, the inlay receiving no deposit of strike metal or electroplated metal.

In connection with Examples 13 and 14 above, an alternative conditioning procedure may be used in place of Step 1 illustrated therein. The coaster as obtained from Step 1 was first thoroughly cleaned and then contacted with a conditioner of the type sold under the trade designation Macuplex XJ-43 Acid-Etchant for a period of 3 minutes at 110 F. After careful rinsing, the coaster was then immersed in an activator sold under the trade designation Macuplex for 3 minutes at 115 F. After 0 rinsing, the coaster was then immersed in an accelerator sold under the trade designation Macuplex for 15 seconds at 100 F.

The thickness of the metal strike formed on the first component in Step 3 of Examples 1 through 14 is a function both of the concentration of metal ions in the strike bath and of the plating time, whereby the desired thickness of metal strike on the surface of the first component may be obtained by suitably controlling these factors. More specifically, in Example 1, if smaller concentrations of copper ion are utilized in the strike solution, then in general, longer times of exposure of the first component to the strike solution should be utilized, and conversely, in general, if greater concentrations of copper ions in the strike solution are utilized, shorter exposure times may be utilized.

Likewise, in the electroplating process of Step 4, both the concentration of the plating ions in the bath and the plating time may be varied, the relationship therebetween being generally inverse in character. More specifically, if lesser concentrations of nickel ion are utilized in the eelctroplating bath, then the plating time should be proportionately increased and conversely if greater concentrations of nickel ions are utilized in the electroplating bath, then the plating time may be reduced.

Other metals may be electroplated upon the metal strike of the coasters in Examples 1 through 14 above in the place of the nickel specified in Step 4 thereof. More specifically, all of the conventional electroplating metals including copper, chromium, zinc, and the like, may be utilized in the place of the nickel illustrated. It will be understood that the plating conditions including bath temperature, plating time and current densities will be altered as is well understood in the art.

In each of the foregoing examples, the plating metal was plated over the strike metal deposit by an electroplating procedure such as that described in Step 4 of Example 1. The plated metal may, however, be deposited by contacting a multi-component workpiece of which a first component thereof has a deposit of strike metal thereon and a second component thereof has no deposit strike metal thereon with an electroless metallizing bath of the type previously described in connection with the strike solution whereby the plating metal is plated over the strike metal deposit by an electroless plating system. The fol- 12 lowing examples illustrate the use of various metallizing baths of the electroless type in whihc a layer of plating metal is plated over the strike metal deposit on the surface of the first component of the workpiece while no metal is plated on the surface of the second component thereof.

EXAMPLE 15 Steps 1, 2 and 3 of Example 1 were repeated to produce thereby a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2 having a first component or base formed of a polypropylene resin sold under the trademark Oleplate and having a deposit of copper metal on the surface thereof, and a second component or inlay formed of a modified phenylene oxide resin sold under the trademark Noryl, on which there is no deposit of copper metal.

Step 4 The two-component coaster was then immersed in an electroless metallizing bath consisting of an aqueous solution containing the following ingredients and used under the conditions indicated:

Nickel sulfate-0.08 mole/ liter Sodium hypophosphite-O.23 mole/liter Lactic anion0.30 mole/ liter Propionic anion-0.03 mole/ liter Lead ion-1 part per million phi-4.6

After a period of 30 minutes, a plated metal coating of nickel metal was plated over the copper metal strike deposit such that only the base portion of the coaster was plated while the inlay portion remained free of any nickel metal deposit.

EXAMPLE 16 Steps 1, 2 and 3 of Example 13 were repeated to produce thereby a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2 having a first component or base formed of a polypropylene resin sold under the trademark Oleplate and having a deposit of nickel metal on the surface thereof, ,and a second component or inlay formed of a modified phenylene oxide resin sold under the trademark Noryl on which there is no deposit of nickel metal.

Step 4 The two-component coaster was next immersed in an electroless metallizing bath consisting of an aqueous solu tion containing the following ingredients and used under the conditions indicated:

Copper sulfate-20 grams/liter Triethanolaminegram/ liter Formaldehyde solution (40% )20 milliters/liter pH12.5

Temperature25 C.

After a period of 30 minutes, a plated metal coating of copper metal was plated over the nickel strike deposit such that only the base portion of the coaster was plated while the inlay part remained free of any copper metal deposit.

EXAMPLE 17 Steps 1, 2 and 3 of Example 1 are repeated to produce thereby a two-component plastic workpiece in the form of a coaster as shown in FIGS. 1 and 2 having a first component or base formed of a polypropylene resin sold under the trademark Oleplate and having a deposit of copper metal on the surface thereof, and a second component or inlay formed of a modified phenylene oxide resin sold under the trademark Noryl, on which there is no deposit of copper metal.

Step 4 The two-component coaster was next immersed in an electroless metallizing bath consisting of an aqueous solution containing the following ingredients and used under the conditions indicated:

Cobalt chloride-50 grams/ liter Rochelle salt-375 grams/liter Ammonium chloride100 grams/ liter Sodium hypophosphite-35 grams/ liter pH9.0

Temperature-98 C.

After a period of 30 minutes, a plated metal coating of cobalt metal was plated over the copper metal strike deposit such that only the base portion of the coaster was plated while the inlay portion remained free of any cobalt metal deposit.

The processes described in the foregoing examples are fundamentally independent of the manner in which the individual components of the multi-component workpiece are joined together. The multi-component workpieces de- Step 1 There was provided a two-component plastic workpiece in the form of two plastic rods as shown in FIG. 3 of the drawings. The first component or section was formed of the polypropylene resin sold under the trademark Oleplate while the second component or section 16 was formed of the modified phenylene oxide resin sold under the trademark Noryl. The two

sections

15 and 16 are joined together by a pin 17 inserted through

channels

21 and 23 provided in each of the

sections

15 and 16 respectively. One end of the pin 17 is in the shape of a truncated cone portion 18 which seats in a truncated cone recess 24 provided in the second compartment or section 16, while the other end of the pin 17 is formed into a head portion 19 fitted within a recess provided in the first component or section 15, the truncated cone portion and head portion of the pin serving to mechanically lock the two

sections

15 and 16 into position.

Steps 2, 3 and 4 of Example 1 were then repeated utilizing the two-component plastic workpiece as described above to produce first a copper metal strike on the first component or section 15 which was thereafter electroplated with nickel plating metal, the second component or section 16 receiving no deposit of strike metal or electroplated metal.

The multi-component plastic workpieces having the individual components thereof joined together by mechanical means such as that described in Step 1 of EX- ample 17 may similarly be treated in accordance with Examples 13 and 14 to provide a deposit of strike metal of electroless nickel and electroless cobalt respectively on the surface of the first component, while the second component thereof receives no deposit of strike metal on the surface thereof. Similarly, a multi-component plastic workpiece having its individual components joined together by mechanical means as set forth above may be plated with a layer of plating metal by contacting the workpiece with metallizing bath of the electroless type as described in Examples 15 through 17 to provide on the surface of the first component thereof a first deposit of strike metal over which is plated a layer of an electroless plating metal consisting of either nickel metal, copper metal or cobalt metal, while the second component thereof receives no deposit of strike metal or plated metal.

Summarizing with respect to the above examples, the processes described herein are equally applicable to other multi-component plastic workpieces whether joined together by double-shot molding or by mechanical interlocking or any other means so long as the component to be plated is chosen from among those synthetic organic plastic resins which will accept an initial deposit of strike metal over which a layer of plating metal may be plated. As has been pointed out, the strike metal may consist of any metal which will render the surface of the component to be plated catalytic in nature, including copper, nickel and cobalt. Furthermore, the plating step may be accomplished by an electroplating system as set forth in Example l or by contacting the workpiece with an electroless metallizing bath as set forth in Example 9. The fundamental advantage of this invention resides in the ability to produce first a multi-component article or workpiece, and then subject that workpiece to the strike metal and plating operations such that at least one component of said workpiece is provided with a layer of plating metal while the remaining components receive no deposit of plated metal.

{From the above it will be seen that there have been provided processes for producing a multi-component plastic workpiece in which at least a first component thereof carries a plated metal coating and at least a second component thereof has no coating of metal plated thereon, which processes fulfill the objects and advantages set forth above. In addition, the processes provide multicomponent workpieces having plated metal coatings on at least one of said components thereof.

While there have been described what are presently considered to be certain preferred embodiments of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as wall within the true spirit and scope of the invention.

What is claimed is:

1. A process of producing a multi-component plastic workpiece in which at least a first component thereof carries a plated metal coating and at least a second component thereof has no metal coating plated thereon, said process comprising the steps of, providing a strike solution, providing a multi-component workpiece including at least a first component formed of a first plastic material on which a meta-l strike is deposited upon application of said strike solution thereto, said first plastic material being selected from the group consisting of polypropylene resins and aciylonitrile-butadiene-styrene resins and at least a second component formed of a second plastic material on which no metal strike is deposited upon application of said strike solution thereto, said second plastic material being selected from the group consisting of polycarbonate resins, modified phenylene oxide resins, polyphenylene oxide resins, polyvinyl chloride resins and stereo-regular polyolefin resins, applying said strike solution to said workpiece to deposit a metal strike on said first component without depositing a metal strike on said second component, and plating a layer of plating metal on said metal strike to provide a plated metal coating on said first component while no metal is plated on said second component.

2. The process of producing a multi-component plastic workpiece as set forth in claim 1, wherein said strike solution consists essentially of an aqueous solution containing strike metal ions and an electroless reducing agent therefor.

3. The process of producing a multi-component plastic workpiece as set forth in claim 2, wherein said strike metal ions are nickel ions and said electroless reducing agent is a hypophosphite.

4. The process of producing a multi-component plastic workpiece as set forth in claim 2, wherein said strike metal ions are copper ions and said electroless reducing agent is formaldehyde.

5. The process of producing a multi-component plastic workpiece as set forth in claim 2, wherein said strike metal ions are cobalt ions and said electroless reducing agent is a hypophosphite.

6. The process of producing a multi-component plastic workpiece as set forth in claim 1, wherein the individual components of said plastic workpiece are joined together by mechanical interlocking.

7. The process of producing a multi-component plastic workpiece as set forth in claim 1, wherein said second component is molded to said first component.

8. The process of producing a multi-component plastic workpiece as set forth in claim 1, wherein each of said plastic materials is a synthetic organic plastic resin.

9. The process of producing a multi-component plastic workpiece as set forth in claim 1, wherein said first plastic material is selected from the group consisting of polypropylene resins and acrylonitrile-butadiene-styrene copolymer resins.

10. The process of producing a rnulti-cornponent plastic workpiece as set forth in claim 1, wherein said second plastic material is selected from the group consisting of polycarbonate resins, modified phenylene oxide resins, polyphenylene oxide resins, resins, polyvinyl chloride resins and stereo-regular polyolefin resins.

11. The process of producing a multi-component plastic workpiece as set forth in claim 1, wherein the plating metal is deposited on said metal strike by electroplatmg.

12. The process of producing a multi-component plastic workpiece as set forth in claim 1, wherein the plating of said plating metal on said metal strike is accomplished by contacting said workpiece with an electroless metallizing bath consisting essentially of an aqueous solution containing electroless metal ions and an electroless reducing agent therefor, thereby to produce on the surface of said first component a coating of the electroless metal while said second component receives no coating of electroless metal thereon.

13. The process of producing a multi-component plastic workpiece as set forth in claim 1, wherein the electroless metal is nickel.

14. The process of producing a multi-component plastic workpiece as set forth in claim 1, wherein said electroless reducing agent is hypophosphite.

15. A process .of producing a multi-component plastic workpiece in which at least a first component thereof carries a metal plated coating and at least a second component thereof has no metal coating plated thereon, said process comprising the steps of, providing a strike solution consisting essentially of an aqueous solution containing electroless metal ions and an electroless reducing agent therefor, providing a multi-component workpiece including at least a first component formed of a first plastic material on which an electroless metal is deposited upon contacting said first component with said strike solution, said first plastic material being selected from the group consisting of polypropylene resins and acrylonitrile-butadiene-styrene resins and at least a second component formed of a second plastic material on which no electroless metal is deposited upon contact of said second component with said strike solution, said second plastic material being selected from the group consisting of polycarbonate resins, modified phenylene oxide resins, polyphenylene oxide resins, polyvinyl chloride resins and stereo-regular polyolefin resins, contacting said workpiece with said strike solution to deposit an electroless metal strike on said first component without depositing an electroless metal strike on said second component, and plating a layer of plating metal on said electroless metal strike to provide a plated metal coating on said first component while no metal is plated on said second component.

16. The process of producing a multi-component plastic workpiece as set forth in claim 15, wherein said electroless metal ions are nickel ions.

17. The process of producing a multi-component plastic workpiece as set forth in claim 16, wherein said electroless reducing agent is a hypophosphite.

18. The process of producing a multi-component plastic workpiece as set forth in claim 15, wherein said electroless metal ions are copper ions.

19. The process of producing a multi-component plastic workpiece as set forth in claim 18, wherein said electroless reducing agent is formaldehyde.

20. The process of producing a multi-component plastic workpiece as set forth in claim 15 wherein said electroless metal ions are cobalt ions.

21. The process of producing a multi-component plastic workpiece as set forth in claim 20, wherein said electroless reducing agent is a hypophosphite.

22. The process of producing a multi-component plastic workpiece as set forth in claim 15, wherein said strike solution has a slightly acidic pH.

23. A process of producing a multi-component plastic workpiece of which at least a first component thereof carries an electroplated metal coating and at least a second component thereof has no metal electroplated thereon, said process comprising the steps of, providing a strike solution, providing a multi-component workpiece including at least a first component formed of a first plastic material on which a metal strike is deposited upon application of said strike solution thereto, said first plastic material being selected from the group consisting of polypropylene resins and acrylonitrile-butadiene-styrene resins and at least a second component formed of a second plastic material on which no metal strike is deposited on application of said strike solution thereto, said second plastic material being selected from the group consisting of polycarbonate resins, modified phenylene oxide resins, polyphenylene oxide resins, polyvinyl chloride resins and stereo-regular polyolefin resins, applying said strike solution to said workpiece to deposit a metal strike on said first component without depositing a metal strike on said second component, and electroplating a layer of metal on said metal strike to provide an electroplated metal coating on said first component while no metal is electroplated on said second component.

24. The process of producing a multi-cornpone-nt plastic workpiece as set forth in claim 23, wherein said electroplated metal is nickel.

25. A process of producing a multi-cornponent plastic workpiece of which at least a first component thereof carries an electroplated metal coating and at least a second component thereof has no metal electroplated thereon, said process comprising the steps of, providing a strike solution consisting essentially of an aqueous solution containing electroless metal ions and an electroless reducing agent therefor, providing a multi-component workpiece including at least a first component formed of a first plastic material on which an electroless metal is deposited upon contacting said first component with said strike solution, said first plastic material being selected from the group consisting of polypropylene resins and acrylonitrile-butadiene-styrene resins and at least a second component formed of a second plastic material on which no electroless metal is deposited upon contact of said second component with said strike solution, said second plastic material being selected from the group consisting of polycarbonate resins, modified phenylene oxide resins, polyphenylene oxide resins, polyvinyl chloride resins and stereo-regular polyolefin resins, contacting said workpiece with said strike solution to deposit an electroless metal strike on said first component without depositing an electroless metal strike on said second component, and electroplating a layer of metal on said metal strike to provide an electroplated metal coating on said first component while no metal is electroplated on said second component.

26. A process of producing a multi-component plastic workpiece in which at least a first component thereof carries a plated metal coating and at least a second component thereof has no metal coating plated thereon, said process comprising the steps of, providing a plating solution, providing a multi-component workpiece including at least a first component formed of a first plastic material on which a metal is deposited upon application of said plating solution thereto, said first plastic material being selected from the group consisting of polypropylene resins and acrylonitrile-butadiene-styrene resins and at least a second component formed of a second plastic material on which no metal is deposited upon application of said plating solution thereto, said second plastic material being selected from the group consisting of polycarbonate resins, modified phenylene oxide resins, polyphenylene oxide resins, polyvinyl chloride resins and stereo-regular polyolefin resins, and applying said plating solution to said workpiece to deposit a plated metal coating on said first component without depositing a plated metal coating on said second component.

27. The process of producing a multi-component plastic workpiece as set forth in claim 26, wherein said strike solution consists essentially of an aqueous solution containing metal ions and an electroless reducing agent therefor.

28. The process of producing a multi-component plastic workpiece as set forth in claim 27, wherein said metal ions are nickel ions and said electroless reducing agent is a hypophosphite.

29. The process of producing a multi-component plastic workpiece as set forth in claim 27, wherein said metal ions are copper ions and said electroless reducing agent is formaldehyde.

30. The process of producing a multi-component plastic workpiece as set forth in claim 27, wherein said metal ions are cobalt ions and said electroless reducing agent is a hypophosphite.

31. A multi-component plastic workpiece comprising, at least a first component formed of a first plastic material, said first plastic material being selected from the group consisting of polypropylene resins and acrylonitrilebutadiene-styrene resins and at least a second component formed of a second plastic material joined thereto, said second plastic material being selected from the group consisting of polycarbonate resins, modified phenylene oxide resins, polyphenylene oxide resins, polyvinyl chloride resins and stereo-regular polyolefin resins, said first component having a layer of metal plating thereon, said metal plating being deposited thereon by simultaneously exposing to a plating bath both said first component and said second component after joinder thereof, thereby to provide a multi-component workpiece having a layer of plated metal on said first component and no plated metal on said second component.

32. The multi-component plastic workpiece as set forth in claim 31, wherein said components are joined together by mechanical interlocking.

33. The multi-component plastic workpiece as set forth in claim 31, wherein said second component is molded to said first component.

34. The multi-component plastic workpiece as set forth in claim 31, wherein each of said plastic materials is a synthetic organic plastic resin.

35. The multi-component plastic workpiece as set forth in claim 31, wherein said first plastic material is selected from the group consisting of polypropylene resins and acrylonitrile-butadiene-styrene copolymer resins.

36. The multi-component plastic workpiece as set forth in claim 31, wherein said second plastic material is selected from the group consisting of polycarbonate resins, modified phenylene oxide resins, polyphenylene oxide resins, polyvinyl chloride resins and stereo-regular polyolefin resins.

37. The multi-component plastic workpiece as set forth in claim 31, wherein said metal plating is an electroless metal layer.

38. The multi-component plastic workpiece as set forth in claim 31, wherein said metal plating is an electroplated metal layer.

39. The multi-component plastic workpiece as set forth in claim 38, wherein said electroplated metal is nickel.

40. A multi-component plastic workpiece as set forth in claim 31, wherein said first component carries an intermediate deposit of strike metal on the surface thereof and a plated metal coating thereover.

41. A multi-component plastic workpiece comprising, at least a first component formed of a first plastic material, said first plastic material being selected from the group consisting of polypropylene resins and acrylonitrile-butadiene-styrene resins and at least a second component formed of a second plastic material joined thereto, said second plastic material being selected from the group consisting of polycarbonate resins, modified phenylene oxide resins, polyphenylene oxide resins, polyvinyl chloride resins and stereo-regular polyolefin resins, said first component having an intermediate deposit of metal strike thereon and said second component having no deposit of metal strike thereon, said first component further having a layer of plating metal over said metal strike, said metal plating being deposited thereon by simultaneously exposing to a plating bath both said first component and said second component after joinder thereof, thereby to provide a multi-component workpiece having a layer of plated metal on said first component and having no plated metal on said second component.

References Cited UNITED STATES PATENTS 3,370,974 2/1968 Hepfer 117-47 3,259,559 7/1966 Schneble, Jr. 117-212 3,307,972 3/ 1967 Ehrhardt 1l7-47 3,378,400 4/1968 Sickles 117-130 FOREIGN PATENTS 938,365 10/1963 Great Britain 117--212 OTHER REFERENCES Plating on Plastics, by H. Narcus, Plating, August 1968, pp. 816-820.

TA-HSUNG TUNG, Primary Examiner T. TUFARIELLO, Assistant Examiner U.S. Cl. X.R.