US3650803A

US3650803A - Metal plating of substrates

Info

Publication number: US3650803A
Authority: US
Inventors: Kingso Chingtsung Lin
Original assignee: Hooker Chemical Corp
Current assignee: Occidental Chemical Corp
Priority date: 1969-07-03
Filing date: 1969-07-03
Publication date: 1972-03-21
Anticipated expiration: 1989-03-21

Abstract

Substrates are plated with metals by subjecting the substrate to low oxidation state phosphorus compounds, usually in a solvent, followed by subjecting the treated substrate to a metal salt or complex thereof. The low oxidation state phosphorus compounds, wherein the phosphorus has an oxidation state of less than 5, i.e., an oxidation number of -3 to +3, can be prepared by reacting elemental phosphorus, preferably elemental white phosphorus (which include various impure or commercial grades sometimes referred to as yellow phosphorus), with a nucleophilic reagent or organometallic compound. The resulting treated substrate is electroless metal plated and/or electroplated to provide an adherently bound metal layer on the substrate. In one embodiment, the substrate is subjected to a low oxidation state phosphorus compound and thereafter electroless metal plated.

Description

United States Patent Lin [54] METAL PLATING OF SUBSTRATES [72] Inventor: Kingso Chingtsung Lin, Niagara Falls,

[73] Assignee: Hooker Chemical Corporation, Niagara Falls, N.Y.

[22] Filed: July3, 1969 21 Appl. No.: 839,080

Related us. Application Data [63] Continuation-impart of Ser. No. 750,477, Aug. 6,

I968, abandoned.

Bayard, J. J., Electrodeposition on Plastic Materials in Metal Industry, May 1940, p. 256

[451 Mar. 21, 1972 Primary ExaminerAlfred L. Leavitt Assistant Examiner-Janyce A. Bell AttorneyPeter F. Casella, Donald C. Studley, Richard P. Mueller, James F. Mudd and Edward A. Meilman [5 7] ABSTRACT Substrates are plated with metals by subjecting the substrate to low oxidation state phosphorus compounds, usually in a solvent, followed by subjecting the treated substrate to a metal salt or complex thereof. The low oxidation state phosphorus compounds, wherein the phosphorus has an oxidation state of less than 5, i.e., an oxidation number of -3 to +3, can be prepared by reacting elemental phosphorus, preferably elemental white phosphorus (which include various impure or commercial grades sometimes referred to as yellow phosphorus), with a nucleophilic reagent or organometallic compound. The resulting treated substrate is electroless metal plated and/or electroplated to provide an adherently bound metal layer on the substrate. In one embodiment, the substrate is subjected to a low oxidation state phosphorus compound and thereafter electroless metal plated.

50 Claims, No Drawings METAL PLATING F SUBSTRATES This is a continuation-in-part of application Ser. No. 750,477, filed Aug. 6, 1968 and now abandoned.

BACKGROUND OF THE INVENTION There is a rapidly increasing demand for metal plated articles, for example, in the production of low cost plastic articles that have a simulated metal appearance. Such articles are in demand in such industries as automotive, home appliance, radio and television and for use in decorative containers and the like. Heretofore, the metal plating of plastics and the like has required many process steps, and generally such processes have been applicable to only one or a few related substrates.

It is an object of this invention to provide a simple process for the metal plating of substrates. Another object of the invention is to provide a process that is applicable to the plating of many different substrates particularly the thermoplastic polymers. A further object of the invention is to provide articles having an adherent metal coating that is resistant to peeling, temperature cycling, and corrosion. Such coatings are electrically conductive whereby static charges are readily dissipated from the surfaces. The metal coatings further serve to protect the articles from abrasion, scratching and marring, reduce their porosity and improve their thermal conductivity. The process of this invention can be used for unidirectional mirrors and the like; water and liquid collecting devices and the like; protective coatings on houses, cars, boats, power line poles, street lights and the like; in thermal control of clothing, houses and the like; and the like.

SUMMARY OF THE INVENTION This invention provides a process which comprises forming a metal-phosphorus coating at the surface of a substrate to render the surface susceptible to conventional electroless plating and/or electrolytic plating.

More particularly, this invention provides a process which comprises subjecting a substrate to a low oxidation state phosphorus compound so as to deposit the low oxidationstate phosphorus compound at the surface of the substrate and thereafter subjecting the thus-treated substrate'to a solution of a metal salt or complex thereof to form a metal-phosphorus coating. In one aspect of the invention, the resultant substrate is electroplated to deposit an adherent metal coating on the substrate. In another aspect of the invention, the treated substrate is subjected to electroless metal plating to deposit an electroless conductive coating onthe surface. Thereafter, the article is electroplated so as to deposit an adherent metal coating of the desired thickness on the electroless conductive coating.

Further, in accordance with the invention, there is provided a process which comprises subjecting a substrate to a low oxidation state phosphorus compound andthereafter subjecting the substrate to electroless metal plating to deposit an electroless conductive coating on the substrate. Thereafter, the article is electroplated so as to deposit an adherent metal coating of desired thickness on the electroless conductive coating.

Also in accordance with the invention, there is provided an article having a metal-phosphorus coating adherently formed at the surface of the substrate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The process of this invention is applicable to substrates, such as plastics and to other substantially nonmetallic substrates. Suitable substrates include, but-are not limited to, cellulosic and ceramic materials such as cloth, paper, wood, cork, cardboard, clay, porcelain, leather, porous glass, asbestos cement, and the like.

Typical plastics to which the process of this invention is applicable include the homopolymers and copolymers of ethylenically unsaturated aliphatic, alicyclic and aromatic hydrocarbons such as polyethylene, polypropylene, polybutene', ethylenepropylene copolymers; copolymersof ethylene or propylene with other olefins, polybutadiene; polymers of butadiene, polyisoprene, both natural and synthetic, polystyrene and polmers of pentene, hexene, heptene, octene, 2-methylpropene, 4-n1ethyl-hexene-I, bicyclo-(2.2.l )-2-heptene, pentadiene, hexadiene, 2,3-dimethylbutadiene-1,3,4- vinylcyclohexene, cyclopentadiene, methylstyrene, and the like. Other polymers useful in the invention include polyindene, indenecoumarone resins; polymers of perhaloethylenes such as poly(tetrafluoroethylene) and poly(monochlorotrifluoroethylene); polymers of acrylate esters and polymers of methacrylate esters, acrylate and methacrylate resins such as ethyl acrylate, n-butyl methacrylate, isobutyl methacrylate, ethyl methacrylate and methyl methacrylate; alkyd resins; cellulose derivatives such as cellulose acetate, cellulose acetate butyrate, cellulose nitrate, ethyl cellulose, hydroxyethyl cellulose, methyl cellulose and sodium carboxymethyl cellulose; epoxy resins; furan resins (furfuryl alcohol or furfural-ketone); hydrocarbon resins from petroleum; isobutylene resins (polyiso-butylene); isocyanate resins (polyurethanes); melamine resins such as melamineformaldehyde and melamine-urea-formaldehyde; oleo-resins; phenolic resins such as phenol-formaldehyde, phenolicelastomer, phenolic-epoxy, phenolic-polyamide, and phenolic-vinyl acetals; polyamide polymers, such as polyamides, polyamide-epoxy and particularly long chain synthetic polymeric amides containing recurring carbonamide groups as an integral part of the main polymer chain; polyester resins such as unsaturated polyesters of dibasic acids and dihydroxy compounds, and polyester elastomer and resorcinol resins such as resorcinol-formaldehyde, resorcinol-furfural, resorcinol-phenol-formaldehyde, resorcinol-polyamide and resorcinol-urea; rubbers such as natural rubber, synthetic polyisoprene, reclaimed rubber, chlorinated rubber, polybu' tadiene, cyclized rubber, butadiene-acrylonitrile rubber, butadiene-styrene rubber, and butyl rubber; neoprene rubber (polychloroprene); polysulfides (Thiokol); terpene resins; urea resins; vinyl resins such as polymers of vinyl acetal, vinyl acetate or vinyl alcohol-acetate copolymer, vinyl alcohol, vinyl chloride, vinyl butyral, vinyl chloride-acetate copolymer, vinyl pyrrolidone and vinylidene chloride copolymer, polyformaldehyde; polyphenylene oxide; polymers of diallyl phthalates and phthalates; polycarbonates of phosgene or thiophosgene and dihydroxy compounds such as bisphenols, thermoplastic polymers of bisphenols and epichlorohydrin (tradenamed Phenoxy polymers); graft copolymers and polymers of unsaturated hydrocarbons and an unsaturated monomer, such as graft copolymers of polybutadiene, styrene and acrylonitrile, commonly called ABS resins; ABS-polyvinyl chloride polymers, recently introduced under the trade name of Cycovin; and acrylic polyvinyl chloride polymers, known by the trade name of Kydex 100.

The polymers of the invention can be used in the unfilled condition, or with fillers such as glass fiber, glass powder, glass beads, asbestos, talc and other mineral fillers, wood flour and other vegetable fillers, carbon in its various forms, dyes, pigments, waxes and the like. If a wax is used as a filler, it has been found that the harder the wax, the more adherent the metal will be bound to the substrate.

The substrates of the invention can be in various physical forms, such as shaped articles, for example, moldings, sheets, rods, and the like; fibers, films and fabrics, and the like.

In the process of the invention, the substrate is subjected to atleast one low oxidation state phosphorus compound, usually in a solvent. The low oxidation state phosphorus compound, wherein the has an oxidation state of less than 5, i.e., an oxidation number of 3 to +3, can be prepared by reacting elemental phosphorus, preferably elemental white phosphorus (which includes various impure or commercial grades sometimes referred to as yellow phosphorus), with a suitable nucleophilic reagent or organometallic compound (including Grignard reagents). Suitable nucleophilic reagents include basic compounds having an unshared pair of electrons on a carbon, oxygen, nitrogen, sulfur, or phosphorus atom. The preferred nucleophilic reagents have the formula M2,,

wherein M is an alkali metal (Group 1A) or an alkaline earth metal (Group 11A), y is l or 2, and Z is hydroxide, alkoxide, amide, sulfite, thiosulfate, mercaptide, cyanate, thiocyanate, cyanide, azide and the like.

The organometallic compounds have the general formula R,.D wherein D is a metal selected from Groups 1A, 11 and l 1 1A ofthe Periodic Table, x is l to 3, and R is alkyl of one to 18 carbon atoms, aryl of six to 18 carbon atoms, alicyclic of five to 18 carbon atoms, aralkyl of six to 18 carbon atoms and alkylaryl of six to 18 carbon atoms. The R groups can be unsubstituted or substituted with halogen, nitro groups and the like. Typical organometallic compounds include di(n-butyl) cadmium, diphenylcadmium, dimethylcadmium, diisopropylcadmium, di(p-nitrophenyl) cadmium, triphenylmethylsodium, dianilinocadmium, diethylzinc, di(o-tolyl) zinc, methylzinc chloride, phenyllithium, butyllithium, cyclohexyllithium, triethylaluminum and the like.

The organometallic compounds include Grignard reagents which are the well-known alkylmagnesium halides such as methylmagnesium iodide, ethylmagnesium bromide, n-propylmagnesium chloride, isopropylmagnesium chloride, phenylmagnesium bromide and the like.

Useful hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydroxide, barium hydroxide and the like.

The metal alkoxides are alcohols or phenols in which the hydrogen atom of the hydroxyl group has been replaced by the metal. Thus, the term alkoxide encompasses alkylates and phenates. In these compounds, Z is OR, which represents the alcohol or phenol without the hydroxylic or phenolic hydrogen and where R is as hereinbefore defined. The alcohol or phenol from which the alkoxide is derived can be unsubstituted or substituted with hydrocarbon groups, halogen, nitro groups and the like. Typical alkoxides are lithium methoxide, lithium ethoxide, sodium methoxide, sodium ethoxide, sodium propoxide, potassium methoxide, potassium ethoxide, cesium ethoxide, barium methoxide, calcium ethoxide, sodium pentadecanoxide, sodium phenate, potassium phenate, calcium phenate, sodium chlorophenate, potassium chlorophenate, barium chlorophenate, sodium phenylethoxide, potassium phenylethoxide, magnesium phenylethoxide, sodium p-nitrophenoxide, calcium p-nitrophenoxide, sodium ,B-naphthoxide, potassium B-naphthoxide, barium ,8- naphthoxide and the like.

The metal amides are compounds where Z is RR"N- wherein R and R" are individually selected from the group consisting ofhydrogen, R and The R groups can be unsubstituted or can be substituted with halogen, nitro groups, hydrocarbon groups and the like. Useful metal amides include sodium amide, potassium amide, lithium amide, cesium amide, magnesium amide, calcium amide, barium amide, sodium anilide, potassium nitroanilide, calcium chloroanilide, sodium ethyl amide, potassium diethyl amide, sodium propyl amide, sodium cyclopentyl-amide, N- sodium acetamide and the like.

Useful sulfites and thiosulfates include sodium sulfite, potassium sulfrte, lithium sulfite, calcium sulfite, barium sulfite, magnesium sulfite, sodium thiosulfate, potassium thiosulfate, calcium thiosulfate, barium thiosulfate, mangesium thiosulfate and the like.

The mercaptides are metallic derivatives of mercaptans in which the sulfur hydrogen is replaced by a metal. Typical examples which include sodium methylmercaptide, potassium ethylmercaptide, cesium propylmercaptide, calcium butylmercaptide, barium octylmercaptide, sodium phenylmercaptide, potassium nitrophenylmercaptide, calcium chlorophenylmercaptide, sodium tolylmercaptide, potassium pethylphenylmercaptide and the like.

Useful cyanate, thiocyanate, cyanide and azide compounds include sodium cyanate, potassium cyanate, barium cyanate, calcium cyanate, sodium thiocyanate, potassium thiocyanate, lithium thiocyanate, magnesium thiocyanide, barium thiocyanate, sodium cyanide, potassium cyanide, strontium cyanide, sodium azide, potassium azide, barium azide and the like.

The phosphorus is reacted with the nucleophilic reagent or organometallic compound in a mole ratio that can vary from /1 to H100 phosphorus to reagent or compound, preferably from lO/l to l/lO. The reaction is generally conducted below the decomposition point of the nucleophilic reagent or organometallic compound and below the boiling point of the solvent, ifa solvent is used, preferably from about 20 C. to about 200 C. and more preferably at about 0 C. to about 60 C. The reaction time varies depending on the nature of the nucleophilic reagent or organometallic compound, the solvent and the temperature but is generally in the range of about 1 minute to 24 hours.

The resulting low oxidation state phosphorus compounds are usually employed in a solvent. The phosphorus can be reacted with a nucleophilic reagent or organometallic compound in the solvent or the phosphorus can be reacted with the reagent or compound and thereafter combined with the solvent. For example, phosphorus can be reacted with sodium ethoxide in the presence of ethanol or the phosphorus can be reacted with sodium ethoxide and combined with ethanol. In a similar manner, the phosphorus can be reacted with a mixture of nucleophilic reagents in a common solvent or reacted with each reagent and the products combined. Suitable solvents or diluents for the low oxidation state phosphorus compounds are solvents or mixtures thereof that dissolve the phosphorus compounds and do not interact with the compounds to rapidly destroy their activity. Solvents that reduce or only slowly destroy the activity of the phosphorus compounds of this in vention can be used if they have compensating properties, such as the property ofswelling the surface of the substrate.

Suitable solvents are generally neutral or only weakly acidic. They can be polar or non-polar. Strongly solvating solvents, either protic or di-polar aprotic are preferred. Solvents that swell a plastic surface or penetrate below the surface without detrimentally affecting the surface are preferable. Typical solvents or diluents can be aliphatic or aromatic and usually contain up to 30 carbon atoms. They include aliphatic and aromatic hydrocarbons, ethers, and thioethers; carbonyl compounds such as esters and ketones; nitrogen-containing compounds such as amides, amines, nitriles and nitro compounds; alcohols; phenols; mercaptans; and halogen-containing compounds. Examples of solvents include alcohols such as methanol, ethanol, propanol, butanol, octyl alcohol, decyl alcohol, benzyl alcohol, cyclohexanol, ethylene glycol, glycerol, and the like; aromatic hydrocarbons of six to 18 carbon atoms such as benzene, toluene, xylene, ethyl benzene, naphthalene, tetralin, and the like; ethers such as methyl ether, ethyl ether, propyl ether, isopropyl ether, methyl t-butyl ether, 3-methoxyhexane, anisol, carbitol, diphenyl oxide, and the like; alkanes of one to 18 carbon atoms such as methane, ethane, propane, hexane, octane, decane, octadecane, cyclopentane, cyclooctatetraene, and the like; dipropyl sulfide; dibutyl sulfide; dimethyl sulfoxide; tetrahydrothiophene; butyl formate; methyl acetate; ethyl acetate, benzyl acetate; phenyl carbonate; formamide; dimethylformamide; acetamide; N methyl-2-pyrrolidone; acetone; nitrobenzene; monochlorobenzene; acetophenone; isophorone;

tetrahydrofuran; halogenated hydrocarbons and halocarbons such as chloroform, carbontetrachloride, trichloroethylene, trichloroethane, dichloropropane, ethyl dibromide, ethylchlorobromide, and the like; aniline; hexylamine; acetonitrile; benzonitrile; hexamethylphosphoramide; dodecylmercaptan; phenols such as phenol, resorcinol, catechol, hydroquinone, para-tertiary-butyl phenol, parachlorophenol, para-phenyl phenol, cresol, thiophenol, mercaptophenol and the like; and the like solvents or diluents.

The amount of low oxidation state phosphorus compounds in solution, as measured by the amount of phosphorus therein, can vary from about 0.0001 weight percent phosphorus based on the total weight of the solution to about a saturated solution, preferably from 0.01 to 0.5 percent phosphorus.

As a result of the treatment with the low oxidation state phosphorus compound, the compound is deposited at the surface of the substrate. By this is meant that the low oxidation state phosphorus compound can be located on the surface, embedded in the surface and embedded beneath the surface of the substrate. The location of the low oxidation state phosphorus compound is somewhat dependent on the action of the solvent on the substrate.

Prior to contacting the substrate with the low oxidation state phosphorus compounds, the surface of the substrate should be clean. However, it is not necessary to subject the surface to special treatment such as etching, polishing and the like. The subjection of the substrate to the solution of low oxidation state phosphorus compounds is generally conducted at a temperature below the softening point of the substrate, and below the softening point of the solvent. Generally, the temperature is in the range of about 30 to 135 C., but preferably in the range of about to 100 C. The contact time varies depending on the nature of the substrate, the solvent and the temperature, but it is generally in the range of about 1 second to 1 hour or more, preferably in the range of 1 to 10 minutes.

Following the first treatment step, the substrate can be rinsed with a solvent, and then dried by merely exposing the substrate to the atmosphere or to inert atmosphere such as nitrogen, carbon dioxide, and the like, or by drying the surface with radiant heaters or in a conventional oven. Drying times can vary considerably, for example, from 1 second to 30 minutes or more, preferably 5 seconds to 10 minutes, more preferably 5 to 120 seconds. The rinsing and drying steps are optional. The treated substrate is thereafter stored before further treatment or can be immediately subjected to the subsequent processing steps.

In the second treatment step of the process of the invention, the phosphorus-treated substrate is contacted with a solution of a metal salt or a complex of a metal salt, which is capable of reacting with the low oxidation state phosphorus compound to form a metal-phosphorus coating. The term metal-phosphorus coating, as used herein, means the coating which is formed at the surface of the substrate. Without being limited to theory, the metal-phosphorus coating may be an ionic compound or a solution (alloy). The metals generally employed are those of Groups 1B, IIB, IVB, VB, VIB, VIIB and VIII of the Periodic Table appearing at pages 6061 of Langes Handbook of Chemistry (Revised tenth Ed.). The preferred metals are copper, silver, gold, chromium, manganese, cobalt, nickel, palladium, titanium, zirconium, vanadium, tantalum, cadmium, tungsten, molybdenum, and the like.

The metal salts that are used in the invention can contain a wide variety of anions. Suitable anions include the anions of mineral acids such as sulfat'e, chloride, bromide, iodide, fluoride, nitrate, phosphate, chlorate, perchlorate, borate, carbonate, cyanide, and the like. Also useful are the anions of organic acids such as formate, acetate, citrate, butyrate, valerate, caproate, heptylate, caprylate, naphthenate, 2-ethyl caproate, cinnamate, stearate, oleate, palmitate, dimethylglyoxime, and the like. Generally the anions of organic acids contain one to 18 carbon atoms.

Some useful metal salts include copper sulfate, copper chloride, silver nitrate and nickel cyanide.

The metal salts can be complexed with a complexing agent that produces a solution having a basic pH 7). Particularly useful are the ammoniacal complexes of the metal salts, in which one to six ammonia molecules are complexed with the foregoing metal salts. Typical examples include NiSO -6NH NiCl 'NH Ni(C H OO) -6NH CuSO.,-6NH CuCl -6NH AgNO '6NH NiSO,-3NH CuSO -4NH Ni(NO '4Nl-l and the like. Other useful complexing agents include quinoline, amines and pyridine. Useful complexes include compounds of the formula MX Q wherein M is the metal ion, X is chlorine or bromine and Q is quinoline. Typical examples include: CoCl- Q CoBr Q NiCl Q NiBr Q Nil Q MnCl Q CuCl Q CuBr Q 2 and ZnCl Q Also useful are the corresponding monoquinoline complexes such as CoCl Q. Useful amine complexes include the mono-(ethylenediamine)-, bis- (ethylenediamine)-, tris(ethylenediamine)-, bis( 1,2- propanediamine)-, and bis-( l,3-propanediamine)- complexes of salts such as copper sulfate. Typical pyridine complexes include NiCl (py and CuCl (py) where py is pyridine.

The foregoing metal salts and their complexes are used in ionic media, preferably in aqueous solutions. However, nonaqueous media can be employed such as alcohols, for example, methyl alcohol, ethyl alcohol, butyl alcohol, heptyl alcohol, decyl alcohol, and the like. Mixtures of alcohol and water can be used. Also useful are ionic mixtures of alcohol with other miscible solvents of the types disclosed hereinbefore. The solution concentration is generally in the range from about 0.1 weight percent metal salt or complex based on the total weight of the solution up to a saturated solution, preferably from about one to about ten weight percent metal salt or complex. The pH of the metal salt or complex solution can range from about 4 to 14, but is generally maintained in the basic range, i.e., greater than 7, are preferably from about 10 to about 13.

The step of contacting the phosphorus compound treated substrate with the solution of metal salt is generally conducted at a temperature below the softening point of the substrate, and below the boiling point of the solvent, if one is used. Generally the temperature is in the range of about 30 to 1 10 C., preferably from about 50 to C. The time of contact can vary considerably, depending on the nature of the substrate, the characteristics of the metal salts employed and the contact temperature. However, the time of contact is generally in the range of about 1.0 to 30 minutes, preferably about 5 to 10 minutes.

Depending on the conditions employed in the two treatment steps, the duration'of the treatments, and the nature of the substrate treated, the resulting treated surface may be either (1) conductive, such that the surface can be readily electroplated by conventional techniques, or (2) nonconductive. In the latter instance the treated surface contains active or catalytic sites that render the surface susceptible to further treatment by electroless plating processes that produce a conductive coating on the plastic surface. Such a conductive coating is then capable of being plated by conventional electrolytic processes.

The treated substrates that results from contacting the phosphorus compound treated surface with a metal salt solution can be subjected to a process that has become known in the art as electroless plating or chemical plating. In a typical electroless plating process, a catalytic surface is contacted with a solution of a metal salt under conditions in which the metallic ion of the metal salt is reduced to the metallic state and deposited on the catalytic surface. A suitable chemical treating bath for the deposition of a nickel coating on the catalytic surface produced in accordance with the process of the invention can comprise, for example, a solution of a nickel salt in an aqueous hypophosphite solution. Suitable hypophosphites include the alkali metal hypophosphites such as sodium hypophosphite and potassium hypophosphite, and the alkaline earth metal hypophosphites such as calcium hypophosphite and barium hypophosphite. Other suitable metal salts for use in the chemical treating bath include the metal salts described hereinbefore with respect to the metal salt treatment of the phosphorus-treated substrate of the invention. Other reducing media include formaldehyde, hydroquinone and hydrazine. Other agents, such as buffering agents, complexing agents, and other additives are included in the chemical plating solutions or baths. Suitable metals, solutions and conditions for electroplating are described in Metal Finishing Guidebook Directory for 1967, published by Metals and Plastics Publications, Inc., Westwood, NJ.

In one embodiment of the invention, wherein electroless metal plating is employed, the metal salt or complex is provided by the electroless metal plating bath, so that the treatment of the phosphorus compound treated substrate with the solution of metal salt or complex thereof can be eliminated as a separate step. Herein, the substrate is subjected to the low oxidation state phosphorus compound and thereafter subjected to electroless metal plating as described hereinbefore.

The treated substrates of the invention can be electroplated by the processes known in the art. The article is generally used as the cathode. The metal desired to be plated is generally dissolved in an aqueous plating bath, although other media can be employed. Generally, a soluble metal anode of the metal to be plated can be employed. ln some instances, however, a carbon anode or other inert anode is used.

The following examples serve to illustrate the invention but are not intended to limit it. Unless specified otherwise, all temperatures are in degrees centigrade and parts are understood to be expressed in parts by weight.

EXAMPLE 1 A half mole of NaOC H was prepared by adding 11.5 grams of sodium to 300 ml. of ethanol. A low oxidation state phosphorus compound was prepared by stirring at room temperature for several hours a mixture of 0.5 mole of white phosphorus with the NaOC H solution. Samples of polyurethane, a graft copolymer of polybutadiene, styrene and acrylonitrile (ABS), and polyvinylchloride were immersed in this solution for about 3 minutes at room temperature, exposed to air for 5 minutes, washed with water and immersed in an electroless bath prepared from 40 ml. ofwater, ml. of 28 percent NH OH, 1.8 grams of NiCl 6H O and 1 gram of NaH PO After 2 minutes in the bath, the plastics had obtained adherent, conductive coatings. The conductivity of each sample was in the range ofO to 20 ohms per 0.75 cm.

EXAMPLE 2 A low oxidation state phosphorus compound was prepared from white phosphorus, ethanol and sodium ethoxide as described in Example 1. A sample of polyurethane was subjected to the compound for 30 seconds at room temperature, washed with water for 30 seconds and immersed in a 5 percent ammoniacal solution of nickel chloride at room temperature for [0 minutes. An adherent nickel-phosphorus coating was formed. The sample was washed with water for 30 seconds and then subjected to an electroless bath containing 100 ml. of NH OH, 1.0 gram of NaH PO and 50 ml. of a solution prepared by dissolving grams of NiCl -6H O in 300 ml. of water. After 95 seconds, the polyurethane was removed and was found to have an adherent, conductive coating.

EXAMPLE 3 A low oxidation state phosphorus compound solution was prepared from 1 mole NaOC H 1 mole yellow phosphorus and 600 ml. of ethanol. An ABS sample was subjected to the solution at room temperature for 2 minutes and then dried in air for 1 minute. The sample was subjected to a solution containing 5 grams of AgNO 100 ml. of water and 100 ml. of concentrated NhqOH for about 5 minutes. The resulting sample had a silver-phosphorus coating at the surface of the substrate. The treated sample was subjected to the electroless bath of Example 2 at 70 C. to form a conductive coating.

EXAMPLES 4l3 Samples ofABS were subjected to a solution ofa low-oxidation state phosphorus compound at room temperature for about 3 minutes, air dried and subjected to electroless metal plating as described in Example 2 to provide adherent, conductive coatings on the substrates. The low oxidation state phosphorus compound solution was prepared for dissolving the following nucleophilic reagents or organometallic compounds in the following solvents and then adding white phosphorus to the solution in a 1 to 1 mole ratio with the reagent or compound:

Example Reagent or Compound Solvent 4 Sodium propoxide Propyl alcohol 5 Sodium butoxide Butanol 6 Sodium hydroxide Methanol 7 Sodium hydroxide Ethanol 8 Sodium ethoxide Ethanol 9 Sodium methoxide Methanol l0 Butylmagnesiurn bromide Eth \l ether ll Sodium amide Ethanol 12 Sodium-scc-butyl mercaptide Ethanol l3 Triethyl aluminum Tetrahydrofuran EXAMPLES 14-26 In these examples, various solvents were employed. Unless otherwise indicated, the substrate was subjected to the low oxidation state phosphorus compounds at room temperature for l to 3 minutes, dried, rinsed with water, and subjected to electroless metal plating as described in Example 2. In each instance, a conductive surface was obtained. Also unless indicated otherwise, the nucleophilic reagent or organometallic compound was added to white phosphorus in the solvent.

EXAMPLES 27-30 Samples of ABS were subjected to a solution for 10 minutes at room temperature prepared by mixing yellow phosphorus, ethanol and sodium ethoxide. The samples were then dried in air for 1 minute, rinsed with water and wiped dry. The plastic strips were thereafter immersed in the following 1 liter electroless baths for 15 minutes (20 minutes in Example 30) to obtain an adherent, conductive coating:

Example Electroless Bath 27 Acid Nickel Bath Nickel chloride 30 g. Sodium glycollate 50 g Sodium hypophosphite 10 pH 4-6 Temperature 190 F.

28 Basic Nickel Bath Nickel chloride 30 g. Sodium citrate g Ammonium chloride 50 g Sodium hypophosphite 10 g. Temperature C.

29 Cobalt Bath Cobalt chloride 30 g Sodium citrate 35 g. NH Cl 50 g. NaH,PO, 20 g. pH 9-10 Temperature 90-95 C.

30 Copper Bath Copper nitrate 15 g.

NaHCO l g. Sodium citrate 30 g. NaOH 30 g. formaldehyde (38%) 100 ml. pH 1 L Room temperature EXAMPLE 31 minutes in the solution, at room temperature, the plastic was air dried for 1 minute, dried in an air circulating oven at 85 C. for 20 minutes, air dried for 1 minute, rinsed with water and wiped dry. The treated specimen was then electroless plated as described in Example 2.

EXAMPLE 32 An ABS disk was subjected for minutes to the low oxidation state phosphorus compound solution of Example 8 at room temperature, air dried for 2 minutes and electroless plated with nickel in a MacDermid Electroless Nickel No. 28 Solution (acid) for 3 minutes. Thereafter, the disk was elec troplated with copper in a Udylite bright acid copper plating bath at a current density of40 amperes per cubic foot. The adhesion of the plated metal to the plastic surface (peel strength), measured by the quantity of force required to pull an inch wide strip of metal away from the plastic surface, was 10.8 pounds per inch.

EXAMPLE 32 Additional methanol was added to the low oxidation state phosphorus compound solution of Example 9. Five days later, an ABS disk was immersed in this solution for 5 minutes at 50 C., air dried for seconds, oven dried (at 85 C.) for 2 minutes, air dried for 15 seconds, rinsed with water for 30 seconds and wiped with a paper towel. The plastic was then electroless plated and electroplated as described in Example 32 except that the time the plastic was in the electroless bath was 2 minutes. The peel strength was determined to be 17.0 pounds per inch.

EXAMPLES 33-39 The following substrates are plated with metals by the procedure of Example 32:

Example Substrate Polyethylene Polystyrene Polymethylmethacrylate Cardboard Paper Asbestos cement WoocL.

EXAMPLES 40-42 Example Substrate 40 Porcelain 4| Neoprene rubber 42 Glass ill EXAMPLE 43 Several samples of ABS were immersed in a solution of a low oxidation state phosphorus compound. The solution was prepared by adding 7 grams of lithium to 600 milliliters of absolute ethanol, adding 3] grams of yellow phosphorus thereto with stirring and thereafter mixing 20 milliliters of the resulting solution with 600 milliliters of ethanol. The phosphorus constituted about 0.20 weight percent based on the total weight of the solution. Immersion time was 3 minutes and the temperature was 25 C. The samples were withdrawn into the air for 3 minutes and then electroless nickel plated for 3 minutes at -88 C. Thereafter, the samples were electroplated as follows: about 2.5 mils of nickel were applied by employing the treated ABS as the cathode, and using a nickel anode, in a Watts Nickel Bath. The resulting average adhesion was 18.0 pounds per inch.

EXAMPLE 44 Example 43 was repeated except that instead of immersing the ABS samples in the low oxidation state phosphorus compound solution, the solution was sprayed on the substrate by an airless spray gun which employed nitrogen. The resulting samples had adherently bound coatings on their surfaces.

This Example illustrates an additional method of subjecting a substrate to the low oxidation state phosphorus compound.

Various changes and modifications can be made in the process and products of this invention without departing from the spirit and scope of the invention. For example, a substrate can be mechanically or chemically etched, if desired, prior to subjection to the low oxidation state phosphorus compound. The various embodiments of the invention disclosed herein serve to further illustrate the invention but are not intended to limit it.

I claim:

1. A process which comprises coating a substrate by subjecting the substrate to at least one reaction product of elemental white phosphorus and a nucleophilic reagent or organometallic compound in a solvent.

2. The process of claim 1 wherein the substrate is a plastic.

3. A process wherein the treated substrate resulting from the process of claim 1 is subjected to electroless metal plating to deposit an electroless conductive coating on the treated substrate.

4. A process wherein the substrate resulting from the process of claim 3 is electroplated to deposit an adherent metal coating on the conductive coating.

5. The process of claim 4 wherein the nucleophilic reagent is sodium ethoxide.

6. The process of claim 4 wherein the nucleophilic reagent is lithium ethoxide.

7. The process of claim 4 wherein the plastic is a graft copolymer of polybutadiene, styrene and acrylonitrile.

8. The process of claim 4 wherein the plastic is polyvinylchloride.

9. The process of claim 4 wherein the plastic is polypropylene.

10. A process which comprises subjecting a substrate to at least one reaction product of elemental white phosphorus and a nucleophilic reagent or organometallic compound in a solvent and thereafter subjecting the treated substrate to a metal salt or complex thereof wherein the metal salt is selected from Groups 1B, 118, NE, VB, VlB, V118 and VIII of the Periodic Table.

11. The process of claim 10 wherein the nucleophilic reagent is an alkali metal alkoxide.

12. A process wherein the treated substrate resulting from the process of claim 10 is subjected to electroless metal plating to deposit aconductive coating on the treated substrate.

l3. A process wherein the substrate resulting from the process of claim 12 is electroplated to deposit an adherent metal coating on the conductive coating.

14. A process wherein the treated substrate resulting from the process of claim is electroplated to deposit an adherent metal coating on the treated substrate.

15. An article having a low oxidation state phosphorus compound deposited at the surface ofa substrate, wherein said low oxidation state phosphorus compound is the reaction product of elemental phosphorus and a nucleophilic reagent or organometallic compound.

16. The article ofclaim wherein the substrate is a plastic.

17. The article of claim 16 wherein the nucleophilic reagent is sodium ethoxide.

18. The article of claim 16 wherein the nucleophilic reagent is lithium ethoxide.

19. The article of claim 16 wherein the plastic is a graft copolymer of polybutadiene, styrene and acrylonitrile.

20. The article of claim 16 wherein the plastic is polyvinyl chloride.

21. The article of claim 16 wherein the plastic is polypropylene.

22. An article having an adherent metal-phosphorus coating on the surface of a substrate, wherein said metal-phosphorus coating is the reaction product of a metal salt or complex thereof and a low oxidation state phosphorus compound, wherein said low oxidation state phosphorus compound is the reaction product of elemental phosphorus and a nucleophilic reagent or organometallic, compound, and wherein the metal of the metal salt or complex thereof is selected from Groups [8, 11B, IVB, VB, VlB, VlIB and VIII ofthe Periodic Table.

23. The article of claim 22 wherein the substrate is a plastic.

24. The article ofclaim 23 wherein the nucleophilic reagent is an alkali metal alkoxide.

25. The article of claim 23 having an adherent metal coating electrolytically deposited on said metal-phosphorus coating.

26. The article of claim 23 having a conductive electroless metal coating deposited on said metal-phosphorus coating.

27. The article ofclaim 26 having an adherent metal coating electrolytically deposited on the conductive coating.

28. The article of claim 27 wherein the plastic is a graft copolymer ofpolybutadiene, styrene and acrylonitrile.

29. The article of claim 27 wherein the plastic is polyvinyl chloride.

30. The article of claim 15 having a conductive electroless metal coating deposited on said low oxidation state phosphorus compound.

31. The article of claim 27 wherein the plastic is polypropylene.

32. The article of claim 30 having an adherent metal coating electrolytically deposited on the conductive coating.

33. The article of claim 32 wherein the substrate is a graft copolymer of polybutadiene, styrene and acrylonitrile.

34. The article of claim 32 wherein the substrate is polyvinyl chloride.

35. The article of claim 32 wherein the substrate is polypropylene.

36. The article of claim 22 wherein said nucleophilic reagent has the formula M2,, wherein M is an alkali metal or an alkaline earth metal, y is 1 or 2, and Z is hydroxide, alkoxide, amide, sulfite, thiosulfate, mercaptide, cyanate, thiocyanate, cyanide or azide.

37. The article of claim 36 wherein the nucleophilic reagent is sodium methoxide.

38. The article of claim 36 wherein the nucleophilic reagent is sodium ethoxide.

39. The article of claim 36 wherein the nucleophilic reagent is lithium ethoxide.

40. The article of claim 22 wherein said organometallic compound has the formula R,D wherein R is alkyl of one to 18 carbon atoms, aryl of six to 18 carbon atoms, alicyclic of five to 18 carbon atoms, aralkyl of six to l8 carbon atoms or alkylaryl of six to 18 carbon atoms, D is a metal selected from Groups 1A, II and "IA of the Periodic Table, and .t is l to 3.

41. The article of claim 40 wherein the organometallic compound is triethyl aluminum.

42. The process of claim 10 wherein said nucleophilic reagent has the formula MZ wherein M is an alkali metal or an alkaline earth metal, y is l or 2, and Z is hydroxide, alkoxide, amide, sulfite, thiosulfate, mercaptide, cyanate, thiocyanate, cyanide or azide.

43. The process of claim 42 wherein the nucleophilic reagent is sodium methoxide.

44. The process of claim 42 wherein the nucleophilic reagent is sodium ethoxide.

45. The process of claim 42 wherein the nucleophilic reagent is lithium ethoxide.

46. The process of claim 42 wherein the nucleophilic reagent is sodium amide.

47. The process of claim 42 wherein the nucleophilic reagent is sodium-sec-butyl mercaptide.

48. The process of claim 10 wherein said organometallic compound has the formula R D wherein R is alkyl or one to 18 atoms, aryl of six to 18 carbon atoms, alicyclic of five to l8 carbon atoms, aralkyl of six to 18 carbon atoms or alkylaryl of six to 18 carbon atoms, D is a metal selected from Groups IA, ll and [HA ofthe Periodic Table, and x is l to 3.

49. The process of claim 48 wherein the organometallic compound is triethyl aluminum.

50. The process of claim 48 wherein the organometallic compound is butylmagnesium bromide.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION mmwo. 65 0 Dated rch 21; 1912 Invent-(8) V Kingso Chingtsung-Lin 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 66, "wherein the" should read ----wherein the 1 phosphorusm Column 6, line 26 "are preferrably" should read ---end preferablyu Column 7, line 62, "Nb 0 Should read -1--J-*.;IH O line 73 "for dissolving" should read ---by dissolving--. Column 8', line 36 ".(C H 21" should read @M.(C H -\1---. Column 9, line 3"NaOH 30 9" should read ms 20 -g-- Column 12, line 41 "alkyl or" should read This certificate supersedes Certificate of Correction issued August 1, 1972.

Signed and. sealed this 19th day of March 197A.

' (SEAL) Attestz EDWARD M.FLETCHER,IJR. c; MARSHALL'DANN Attest ing Officer Commissioner of Patents zg g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,650,803 Dated March 21, 1972 I v Kingso Chingtsung Lin It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

I Column 6, line 26 "are preferrably" should read --and preferably----. Column 7, line 62, "Nh OH" .should read -.-I ,IH OH---; line 73 "for dissolving" should read --by dissol\zing--.. Column 8, line 36 "(C H a1" should read (C H Al--. Column 9, line 3"NaOH 30 9" should read --NaOH 20 g-. Column 12, line 41 "alkyl or" should read ---a1kyl of-.

Signed and sealed this 1st day of August 1972-.

(SEAL) Attest':

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer I Commissioner of Patents

Claims

2. The process of claim 1 wherein the substrate is a plastic.
3. A process wherein the treated substrate resulting from the process of claim 1 is subjected to electroless metal plating to deposit an electroless conductive coating on the treated substrate.
4. A process wherein the substrate resulting from the process of claim 3 is electroplated to deposit an adherent metal coating on the conductive coating.
5. The process of claim 4 wherein the nucleophilic reagent is sodium ethoxide.
6. The process of claim 4 wherein the nucleophilic reagent is lithium ethoxide.
7. The process of claim 4 wherein the plastic is a graft copolymer of polybutadiene, styrene and acrylonitrile.
8. The process of claim 4 wherein the plastic is polyvinylchloride.
9. The process of claim 4 wherein the plastic is polypropylene.
10. A process which comprises subjecting a substrate to at least one reaction product of elemental white phosphorus and a nucleophilic reagent or organometallic compound in a solvent and thereafter subjecting the treated substrate to a metal salt or complex thereof wherein the metal salt is selected from Groups IB, IIB, IVB, VB, VIB, VIIB and VIII of the Periodic Table.
11. The process of claim 10 wherein the nucleophilic reagent is an alkali metal alkoxide.
12. A process wherein the treated substrate resulting from the process of claim 10 is subjected to electroless metal plating to deposit a conductive coating on the treated substrate.
13. A process wherein the substrate resulting from the process of claim 12 is electroplated to deposit an adherent metal coating on the conductive coating.
14. A process wherein the treated substrate resulting from the process of claim 10 is electroplated to deposit an adherent metal coating on the treated substrate.
15. An article having a low oxidation state phosphorus compound deposited at the surface of a substrate, wherein said low oxidation state phosphorus compound is the reaction product of elemental phosphorus and a nucleophilic reagent or organometallic compound.
16. The article of claim 15 wherein the substrate is a plastic.
17. The article of claim 16 wherein the nucleophilic reagent is sodium ethoxide.
18. The article of claim 16 wherein the nucleophilic reagent is lithium ethoxide.
19. The article of claim 16 wherein the plastic is a graft copolymer of polybutadiene, styrene and acrylonitrile.
20. The article of claim 16 wherein the plastic is polyvinyl chloride.
21. The article of claim 16 wherein the plastic is polypropylene.
22. An article having an adherent metal-phosphorus coating on the surface of a substrate, wherein said metal-phosphorus coating is the reaction product of a metal salt or complex thereof and a low oxidation state phosphorus compound, wherein said low oxidation state phosphorus compound is the reaction product of elemental phosphorus and a nucleophilic reagent or organometallic, compound, and wherein the metal of the metal salt or complex thereof is selected from Groups IB, IIB, IVB, VB, VIB, VIIB and VIII of the Periodic Table.
23. The article of claim 22 wherein the substrate is a plastic.
24. The article of claim 23 wherein the nucleophilic reagent is an alkali metal alkoxide.
25. The article of claim 23 having an adherent metal coating electrolytically deposited on said metal-phosphorus coating.
26. The article of claim 23 having a conductive electroless metal coating deposited on said metal-phosphorus coating.
27. The article of claim 26 having an adherent metal coating electrolytically deposited on the conductive coating.
28. The article of claim 27 wherein the plastic is a graft copolymer of polybutadiene, styrene and acrylonitrile.
29. The article of claim 27 wherein the plastic is polyvinyl chloride.
30. The article of claim 15 having a conductive electroless metal coating deposited on said low oxidation state phosphorus compound.
31. The article of claim 27 wherein the plastic is polypropylene.
32. The article of claim 30 having an adherent metal coating electrolytically deposited on the conductive coating.
33. The article of claim 32 wherein the substrate is a graft copolymer of polybutadiene, styrene and acrylonitrile.
34. The article of claim 32 wherein the substrate is polyvinyl chloride.
35. The article of claim 32 wherein the substrate is polypropylene.
36. The article of claim 22 wherein said nucleophilic reagent has the formula MZy wherein M is an alkali metal or an alkaline earth metal, y is 1 or 2, and Z is hydroxide, alkoxide, amide, sulfite, thiosulfate, mercaptide, cyanate, thiocyanate, cyanide or azide.
37. The article of claim 36 wherein the nucleophilic reagent is sodium methoxide.
38. The article of claim 36 wherein the nucleophilic reagent is sodium ethoxide.
39. The article of claim 36 wherein the nucleophilic reagent is lithium ethoxide.
40. The article of claim 22 wherein said organometallic compound has the formula RxD wherein R is alkyl of one to 18 carbon atoms, aryl of six to 18 carbon atoms, alicyclic of five to 18 carbon atoms, aralkyl of six to 18 carbon atoms or alkylaryl of six to 18 carbon atoms, D is a metal selected from Groups IA, II and IIIA of the Periodic Table, and x is 1 to 3.
41. The article of claim 40 wherein the organometallic compound is triethyl aluminum.
42. The process of claim 10 wherein said nucleophilic reagent has the formula MZy wherein M is an alkali metal or an alkaline earth metal, y is 1 or 2, and Z is hydroxide, alkoxide, amide, sulfite, thiosulfate, mercaptide, cyanate, thiocyanate, cyanide or azide.
43. The process of claim 42 wherein the nucleophilic reagent is sodium methoxide.
44. The process of claim 42 wherein the nucleophilic reagent is sodium ethoxide.
45. The process of claim 42 wherein the nucleophilic reagent is lithium ethoxide.
46. The process of claim 42 wherein the nucleophilic reagent is sodium amide.
47. The process of claim 42 wherein the nucleophilic reagent is sodium-sec-butyl mercaptide.
48. The process of claim 10 wherein said organometallic compound has the formula RxD wherein R is alkyl or one to 18 atoms, aryl of six to 18 carbon atoms, alicyclic of five to 18 carbon atoms, aralkyl of six to 18 carbon atoms or alkylaryl of six to 18 carbon atoms, D is a metal selected from Groups IA, II and IIIA of the Periodic Table, and x is 1 to 3.
49. The process of claim 48 wherein the organometallic compound is triethyl aluminum.
50. The process of claim 48 wherein the organometallic compound is butylmagnesium bromide.