JPS6252039B2 - - Google Patents

Description

[Detailed description of the invention]

[Related Applications] The present invention is disclosed in U.S. Patent Application No. 495,793 (filing date 1983).
This corresponds to a continuation-in-part application (CIP) filed on May 23, 2007), which is a related invention of U.S. Pat. No. 4,384,929. [Industrial Application Field] This invention relates to an improved method for preventing corrosion by electrodepositing a nickel-containing composite plating film on a metal substrate that is susceptible to corrosion. BACKGROUND OF THE INVENTION Composite electroplating consists of three nickel-containing layers in close contact with each other, each layer having a controlled thickness and a controlled sulfur content. The outermost plating layer is usually coated with a known chrome plating, which significantly improves the corrosion resistance of the base metal outdoors compared to a single or double layer of nickel-containing plating of the same thickness. It is elevated. Such nickel-containing composite plating can be applied to steel,
Copper, brass, aluminum or zinc die casting, etc.
It is widely used in industry to protect base metals exposed to outdoor conditions, especially marine conditions and automotive service conditions. Favorable results in terms of corrosion resistance can also be achieved by applying such a nickel-containing composite plating layer to the surface of a plastic substrate which has previously been provided with a conductive coating such as a copper metal layer, using known means. Representative of such plastic materials that can be plated are ABS, polyolefins, polyvinyl chloride and phenol formaldehyde resins. The use of such composite nickel-containing platings in conjunction with plastic substrates substantially reduces or eliminates so-called "green" corrosion spots caused by corrosive action on copper or flash layers. [References related to the prior art] Typical examples of nickel-containing composite electroplating methods and compositions thereof are disclosed in US Pat. No. 3,090,733 and US Pat. No. 3,703,448. According to the above-mentioned US Pat. No. 3,090,733, there is a method of electrodepositing three layers of nickel-containing plating film on a substrate,
The plating bath for applying this intermediate nickel layer contains at least some sulfur compounds;
This method allows a certain amount of sulfur to be mixed into the nickel-containing intermediate layer, thereby imparting the required adhesion between the composite layers and achieving corrosion resistance of the base material. Disclosed.
Improvements in this method are described in the aforementioned U.S. Pat.
No. 3,703,448 discloses a method in which a sulfur compound consisting of at least a nitrile or an amide thiosulfonate is used in the bath for electrodepositing the intermediate layer. [Object of the Invention] [Benefits and Advantages of the Invention] The method of the present invention provides a further improved method over the compositions and methods disclosed in the two aforementioned patents, By incorporating at least a new and valuable sulfur compound into the plating bath for interlayer electrodeposition, the stability of the bath under agitation is improved and the plating speed is increased by operating at high temperature and low pH. This makes it possible to increase the amount of additive compounds and reduce the consumption of additive compounds. The sulfur compounds used in this invention are easily maintained at optimum concentrations because they are easy to analyze in the bath, and the bath for the outer nickel-containing layer is not contaminated by this sulfur additive compound carried over from the bath for the intermediate layer. It also has the advantage that it does not significantly affect the sulfur concentration in the outer nickel-containing layer. The advantages listed below are because water washing is not normally performed between the intermediate plating step and the outer nickel plating step, and in some cases the final This is an important advantage due to the fact that the coverage of electrodeposited chromium films may be inhibited. DESCRIPTION OF THE INVENTION Benefits and advantages of the present invention include sufficient nickel ions to precipitate a nickel-containing interlayer and a sulfur content in the precipitated nickel-containing interlayer of from about 0.05 to about 0.5% by weight. A general formula that exists in such quantities that

[Formula] and

[wherein, X is S, NH; R is H, ^R1 ; ^R1 is -( _CH2 ) _o , _-SO3M , -( _CH2 ) _oCO2M ; n is an integer from 1 to ₄ ; Y is -SO ₃ M; M represents Na, K, NH ₄ , H]

This is achieved by preparing an aqueous acidic solution containing a thiazole compound and/or a thiazoline compound selected from the group consisting of the compounds represented by and mixtures thereof according to the proposal for the composition of the invention. Can be done. In order to keep the sulfur concentration in the intermediate layer within the above range, the thiazole compound and/or
or the thiazoline compound is typically about 0.01 to about
It is included in an amount of 0.4g/, preferably about 0.03 to about 0.1g/. The interlayer bath also desirably includes optional wetting agents and buffering agents such as boric acid. According to the method proposal of the present invention, the metal substrate or the plastic substrate having a conductive surface is first made of nickel having a film thickness of about 0.15 to about 1.5 mils (3.8 to 38 microns) and an average sulfur concentration of less than about 0.03% by weight. A containing inner layer is then electrodeposited with a film thickness of about 0.005 to about 0.2 mil (0.127 to 5.1μ) and an average sulfur concentration of about 0.05 to about 0.5.
A nickel-containing middle layer is electrodeposited, and a nickel-containing outer layer having a thickness of about 0.2 to about 1.5 mils (5.1 to 38 microns) and an average sulfur concentration of about 0.02 to about 0.15 weight percent. The sulfur concentration in the outer nickel layer is lower than that in the middle layer, but higher than that in the substantially sulfur-free inner layer. Each of the three layers of nickel content is electrodeposited from a Watt-type nickel plating bath, with thiazole and/or thiazoline additive compounds in the bath for the intermediate layer.
It is contained in an amount sufficient to eutectoid the required sulfur content in the layer. Further, the outer bath contains an organic sulfur compound as described below in an amount sufficient to eutectoid the required sulfur content in the layer. Individual baths typically operate within about room temperature (20°C) to about 85°C, and in the case of acidic baths, a pH range of about 1 to 6. [Description of preferred embodiments] This nickel-containing composite plating is characterized in that at least the bath for the intermediate layer contains a sulfur compound consisting of a special type of thiazole and/or thiazoline compound or a derivative thereof as described below. Other than that, U.S. Patent No. 3090733 and U.S. Patent No. 3703448
Precipitation is carried out using a waxing bath of the type described in the publication. Therefore, the plating bath for depositing the nickel plating of the inner layer may be a Watt type bath, a fluoroborate bath, a high chloride bath, a sulfamate nickel plating bath or substantially any of the known types. Consists of a sulfur-free semi-bright nickel bath. The bath for electrodepositing the nickel-containing interlayer is of the same type as the bath for the inner layer, but with an appropriate amount of thiazole and/or to eutectoid the required sulfur content into the interlayer. It further includes a thiazoline additive compound. Similarly, the bath for electrodepositing the outer nickel-containing layer is similar to that for the intermediate layer, but
The only difference is that the amount of sulfur-containing compounds other than thiazole and/or thiazoline compounds in the bath is controlled such that the net sulfur content in the outer layer is lower than the sulfur content in the middle layer. . If a decorative finish is required, the nickel-containing outer layer may be used as described in U.S. Pat. No. 2,512,280.
Preferably, the film is produced using a bright nickel plating bath using one or more organic sulfooxygen compounds as listed in the table of publication No. 2800440, and these brightener compounds are unsaturated. It is preferable to impart both smoothness and glitter by using a compound or an amine compound in combination. These three nickel-containing baths may also optionally contain bath-soluble and compatible wetting agents to prevent pitting, boric acid, formic acid, citric acid, acetic acid, fluoroboric acid, and other buffers. Suitable baths for the electrodeposition of the inner nickel-containing layer are Watt-type baths containing about 200 to about 400 g of nickel sulfate hexahydrate, about 30 to about 100 g of nickel chloride hexahydrate, and about 30 to about 60 g/b of boron as a buffering agent. This bath temperature is from about room temperature (20℃) to about 85℃ or less, and the pH is about 1 to about 6.
is within the range of The nickel-containing intermediate layer with a high sulfur content is the soaking bath used for the inner layer, with an additional layer of about 0.01
~about 0.4g/, preferably about 0.03 to about 0.1g/
The following general expression for

[Formula] and

[wherein, X is S, NH; R is H, ^R1 ; ^R1 is -( _CH2 ) _o , _-SO3M , -( _CH2 ) _oCO2M ; n is an integer from 1 to ₄ ; Y is -SO ₃ M; M represents Na, K, NH ₄ , H]

and mixtures thereof. Particularly preferred thiazole compounds falling within the first structural formula are sodium 2-mercaptothiazolepropanesulfonate and sodium 2-aminothiazolepropanesulfonate. Particularly preferred thiazoline compounds falling within the second structural formula are sodium 1-amino-5-sulfothiazoline and 2-mercaptothiazoline. The required amount of thiazole and/or thiazoline additive compounds to be added to the plating bath for the middle nickel-containing layer depends on the molecular weight of the compound or mixture used, the concentration of other components in the bath, the operating parameters of the bath and the outer nickel layer. It varies depending on the relative concentration of sulfur in it. Typically, the sulfur content in the interlayer is between about 0.05 and about
The thiazole and/or thiazoline additive compound is controlled at 0.5% by weight, preferably about 0.1 to about 0.2% by weight. Such sulfur content is typically achieved when using a concentration of about 0.03 to about 0.1 g/concentration of either or a mixture thereof. The outer nickel-containing layer is electrodeposited from the same bath used to electrodeposit the inner nickel layer, but
The bath for this outer layer contains a suitable sulfur compound to reduce the amount of sulfur eutectoided into the outer nickel layer.
The only difference is that it is within the range of 0.02 to about 0.15% by weight. Suitable sulfur compounds include, for example, sodium allylsulfonate, sodium styrenesulfonate, saccharin, benzenesulfonamide, naphthalenetrisulfonic acid,
Compounds such as benzenesulfonic acid and others commonly used in bright, blank finish nickel plating baths. Thiazole and/or thiazoline additives, benzenesulfinates and nitrile or amide thiosulfonates are generally not preferred. In any case, the sulfur content in the outer layer is less than the sulfur content in the middle layer and greater than that in the inner layer. The sulfur content of the inner layer is approximately 0.03
It should be less than or equal to 0.01% by weight, preferably less than about 0.01% by weight. In the proposed method of the invention, this three-layer composite nickel-containing plating is usually applied subsequently without an intermediate water washing step. This composite plating layer is then applied to a substrate surface, typically having a copper, brass, nickel, cobalt or nickel-iron alloy strike. The inner nickel layer is usually thicker than the outer layer. In order to produce the best results regarding the corrosion resistance performance of this composite plating film,
The ratio of inner layer thickness to outer layer thickness is approximately 50:50 to approximately
A range of 80:20 is recommended. The thickness of the intermediate layer is approx.
It is typically 0.005 to about 0.2 mils (0.127 to 5.1 microns) with a nickel-containing layer of about 0.2 to about 1.5 mils (5.1 to 38 microns) on the outside. To achieve the best corrosion resistance and decorative appearance, a final bright known chrome plating or microcrack chrome plating or microporous chrome plating is usually applied to the surface of the outer layer.
A coating thickness of 0.005 to about 0.2 mils (0.127 to 5.1 microns) is preferred. For substrates that are exposed to milder corrosive conditions, the inner and outer nickel-containing layers can be as thick as about 0.15 mils (4.2 microns) to provide significantly improved corrosion resistance. This nickel-containing layer of composite plating contains known amounts of other conventional contaminant components which enter the bath by entrainment or otherwise and become incorporated into the plating film. Additionally, cobalt can also be present in significant amounts in the nickel-containing layer, and the amount can be up to about 50% cobalt.
However, for general purposes it has been found that it is preferable for the inner nickel-containing layer to consist of nickel as pure as possible. [Examples] Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples unless it departs from the gist of the present invention. Example 1 Approximately 40 oz/gal (300 g/) of nickel sulfate hexahydrate, 8 oz/gal (60 g/)
Test Solution A was prepared consisting of a Watt-type nickel plating solution containing 6 oz/gal (45 g/) of nickel chloride hexahydrate and 6 oz/gal (45 g/) of boric acid. 800ml
of test solution A was placed in one container equipped with a nickel anode and an air agitator. The pH of this test solution A was adjusted to 2.5, and the bath temperature was raised to 60°C. 75 mg of dihexyl sulfosuccinate/
of lubricant was added to this test solution A. Test solution B was prepared by adding 35 mg of sodium 2-mercaptothiazolepropanesulfonate to test solution A. When nickel oil was precipitated from test solution B, this oil was
It contained 0.127% sulfur. The method for producing this Nickelf oil was as follows. A 2 inch by 4 inch (5 cm/10 cm) steel panel was first electrolytically cleaned in an alkaline cleaner, then rinsed with water and immersed in a 20% sulfuric acid solution. It was then washed with water and a nickel strike layer was applied in Woods nickel strike solution. The panels were passivated by anodic electrolysis in an alkaline detergent for 1-2 seconds. The panel was then subjected ^to 35
Plated in test solution B for 1 minute. The panels were then rinsed with water, dried and the edges were cut to remove the resulting Nickelf oil. Example 2 Test Solution C was prepared according to the method of Example 1 by adding 50 mg/sodium 2-mercaptothiazolepropanesulfonate into Test Solution A. Nickelf oil was prepared by the method of Example 1 and contained 0.175% sulfur. Example 3 Test solution D was prepared by adding 35 mg/l of 2-amino-5-sulfothiazoline sodium salt to test solution A. When Nickelf oil was prepared according to the method described in Example 1, the sulfur content was 0.150%. Example 4 Test solution E was prepared by adding 50 mg of 2-amino-5-sulfothiazoli sodium salt to test solution A, and nickel oil was prepared according to Example 1. The sulfur content was It showed 0.201%. Example 5 Test solution F was prepared by adding 35 mg of sodium 2-aminothiazolepropanesulfonate to test solution A, and nickel oil was prepared according to the method of Example 1. The sulfur content of this foil was 0.132%. Example 6 Test solution G was prepared by adding 50 mg of sodium 2-aminothiazolepropanesulfonate to test solution A, and nickel oil was prepared according to the method of Example 1. The sulfur content of this foil was found to be 0.178%. Example 7 Test solution H was prepared by adding 10 mg/2-mercaptothiazoline to test solution A, and nickel oil was prepared according to the method described in Example 1. The sulfur content of this foil was found to be 0.139% by chemical analysis. Example 8 A test solution was prepared by adding 20 mg/2-mercaptothiazoline to test solution A, and a nickel oil was prepared according to the method described in Example 1. The sulfur content of this foil is
It showed 0.305%. Example 9 Prepare test solution C as described in Example 2,
A 1.25 inch x 6 inch (3.2 cm x 15 cm) steel panel was plated under the conditions described in Example 1 with one edge rolled to create an area of significantly lower current density.
Plating was carried out for 7 minutes at a current density of 30 ASF (3.2 A/Dm ² ). The deposited nickel film was semi-glossy and had good coverage throughout the low current density to high current density range. The test solutions B to I described in the examples above are very satisfactory as plating baths for depositing nickel-containing intermediate plating layers with sulfur concentrations within the preferred range of about 0.05 to 0.3% by weight. This thiazole and/or thiazoline additive compound improves the stability of the bath and enables high speed plating, and even if the intermediate layer plating bath is brought into the outer layer plating bath, the outer It has the advantage that it does not significantly affect the physical properties and sulfur content of the nickel-containing layer. It has been found that increasing the bath PH reduces the sulfur content in the plated film when using such thiazole and/or thiazoline additive compounds. Therefore PH approx.
Operating the interlayer bath at 2.5 will result in a satisfactory amount of sulfur in the interlayer. However, even when this additive is introduced into the bright nickel bath for the outer nickel-containing layer, which is typically operated at a pH of about 3.5 to about 4.5, the sulfur content in the bright nickel outer plating increases noticeably. There's nothing to do. Example 10 To test solution A, 25 mg/50 mg/2-mercaptothiazoline with a molecular weight of 119.2 was added.
and 100 mg/added to test solutions J, K and L
was prepared. Brass-like exterior panels and Nickelf oil from each of test solutions J, K, and L at bath temperatures of approximately 135 to
Plating was carried out at 145°C (57 to 63°C) and pH 2.5 with air stirring. In each solution 75 mg/dihexyl sulfosuccinate was added as a wetting agent. This 1" x 6" (2.5cm x 15cm) brass-like appearance panel was first electrolytically cleaned in an alkaline cleaner, rounded at one end to create a low current density area, rinsed with water, soaked in 20% sulfuric acid,
Wash with water, then about 40 ASF in this test solution
(4.3A/Dm ² ) for 5 minutes. This brass-like panel was then unrolled and the overall appearance and adhesion of the film in the high current density and low current density regions was evaluated. This nickel oil made as described in Example 1 was also chemically analyzed for percent sulfur content. According to the results, the sulfur content of the Nickelf oil prepared from Solution J was 0.348%, the sulfur content of the Nickelf oil prepared from Solution K was 0.396%, and the sulfur content of the Nickelf oil prepared from Solution L was 0.848%. This additive compound, when used at the same general molecular concentration as the compounds described in the previous examples, significantly increases the sulfur content in the nickel layer to the extent that it is sufficient for the outer nickel layer of this composite plating. It can be seen that the sulfur content is higher than the level normally desired to achieve close adhesion. Nevertheless, the general appearance of this panel was satisfactory and the adhesion was acceptable. Therefore, the concentration of 2-mercaptothiazoline in test solutions H and I of Examples 7 and 8
It is preferable to control the sulfur content to about 60 mg/or less according to the composition of the sulfur content, so as to form an intermediate nickel layer with a preferable sulfur content. Since it is evident that widely different embodiments may be constructed without departing from the spirit and scope of the invention, this invention is not limited to the specific embodiments thereof, except as limited in the scope of the following claims. It is not something that will be done.

Claims (1)

[Claims] 1. A nickel-containing inner layer having an average sulfur content of 0.3% by weight or less is electrodeposited on a substrate, and the average sulfur content is 0.05% by weight.
A composite plated layer comprising a cohesive nickel-containing intermediate layer of ~0.5% by weight electrodeposited on the inner layer and an adhesive nickel-containing outer layer having an average sulfur content of 0.02 to 0.15% by weight electrodeposited on the intermediate layer. A method of electrodeposition comprising three nickel-containing layers, wherein the average sulfur content of the outer layer is lower than the average sulfur content of the intermediate layer and higher than the average sulfur content of the inner layer. In a method of electrodeposition on a substrate for composite nickel plating, a sufficient amount of nickel ions is deposited to deposit a desired nickel-containing intermediate layer, and the sulfur content in the deposited nickel-containing intermediate layer is adjusted to a desired content. a thiazole and/or a thiazoline additive compound present in an amount sufficient to provide the intermediate nickel-containing layer;
Or the thiazoline additive compound has the general formula [Formula] and [Formula] [wherein, X is S, NH; R is H, R ¹ ; R ¹ is -(CH ₂ ) _o , -SO ₃ M, -(CH ₂ ) _{o CO2M} ; n is an integer from 1 to 4; Y is _-SO3M ; M represents Na, K, _NH4 , H] and mixtures thereof; An improvement method. 2. Process according to claim 1, characterized in that the additive compound is present in the bath in such an amount that the sulfur content in the intermediate layer that is precipitated is between 0.1 and 0.2% by weight. 3. Process according to claim 1, characterized in that the additive compound is selected from 2-mercaptothiazolepropanesulfonic acid and its salts. 4. Process according to claim 1, characterized in that the additive compound is selected from 2-amino-5-sulfothiazoline and its salts. 5. Process according to claim 1, characterized in that the additive compound is selected from 2-aminothiazolepropanesulfonic acid and its salts. 6. Process according to claim 1, characterized in that the additive compound is selected from 2-mercaptothiazoline and its salts. 7. Process according to claim 1, characterized in that the additive compound is present in an amount of 0.01 to 0.4 g/g. 8. Process according to claim 1, characterized in that the additive compound is present in an amount of 0.03 to 0.1 g/g. 9. The inner layer is 0.15-1.5 mil (3.8-38μ), the middle layer is 0.005-0.2 mil (0.127-5.1μ), and the outer layer is 0.2-1.5 mil (5.1-38μ). A method according to claim 1.