CA2207179A1 - Zinc phosphate conversion coating composition and process - Google Patents
Zinc phosphate conversion coating composition and processInfo
- Publication number
- CA2207179A1 CA2207179A1 CA002207179A CA2207179A CA2207179A1 CA 2207179 A1 CA2207179 A1 CA 2207179A1 CA 002207179 A CA002207179 A CA 002207179A CA 2207179 A CA2207179 A CA 2207179A CA 2207179 A1 CA2207179 A1 CA 2207179A1
- Authority
- CA
- Canada
- Prior art keywords
- conversion
- treatment
- ions
- bath
- coating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
- C23C22/08—Orthophosphates
- C23C22/12—Orthophosphates containing zinc cations
- C23C22/16—Orthophosphates containing zinc cations containing also peroxy-compounds
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
- C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
- C23C22/362—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also zinc cations
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
- C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
- C23C22/364—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also manganese cations
- C23C22/365—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also manganese cations containing also zinc and nickel cations
Abstract
A zinc phosphate conversion coating composition which is accelerated only with nitrogen free organic peroxides is low-polluting and able to form uniform, fine, and dense conversion coatings that exhibit an excellent paint adherence when thin and excellent lubricity/lubricant carrier quality when thick.
Description
CA 02207179 1997-06-0~
Description ZINC PHOSPHATE CONVERSION COATING COMPOSITION AND PROCESS
Technical Field This invention relates to zinc phosphate-based conversion treatment baths which can be applied to a variety of metal substrates, for example, steel, steelsheet, galvanized steel sheet, and the like. More particularly, this invention re-lates to a zinc phosphate-based conversion bath and to a surface treatment method that are able to form a fine, dense, and uniform conversion coating on metal surfaces and that are ~Iso able to induce fine-crystal formation in the con-version coating.
Background Art ~o The execution of a zinc phosphate-based conversion treatment on various metals prior to the coating or plastic working thereof is known at present for the purpose of improving the paint adherence and post-paint corrosion resistance and improving the lubrication during plastic working.
The conversion treatment baths used for zinc phosphate-based conver-15 sion treatment are essentially acidic aqueous solutions that contain zinc ions, phosphate ions, and oxidizing agent(s). Nitrite salts, chlorate salts, hydrogen peroxide, organic nitro compounds, hydroxylamine, and the like, are ordinarily co"sidered for this oxidizing agent. These oxidizing agents are typically calledconversion "accelerators" bec~ se they ~unction to accelerate the conversion re-20 actions. Nitrate salts may be prese, IL ~n conversion baths, but--because, in theco,)cer,l,cliu, ,s usually presenl in zinc phos~chate-based conversion baths, nitrate ions do not exercise an oxidizing activity sufficient to convert ferrous ions sub-stantially completely to ferric ions--nitrate ions must be distinguished from the conversion accelerators.
One important role of conversion accelerators during the zinc phosphate based conversion treatment of ferriferous metals is to oxidize the divalent ironions eluting into the conversion bath to trivalent iron ions. For example, the conversion reactions are inhibited when divalent iron ions accumulate in the conversion bath during the continuous conversion treatment of fe" irerous metals, 30 and the role of the conversion accelerator in inhibiting this accumulation of CA 02207179 1997-06-0~
W O96/17976 PCTrUS95/15227 divalent iron ions is thus crucial.
However, each of these already kno~n conversion accelerators is associ-ated with problems that must be addressed. For example, in the case of the ni-trite salts, which are the most widely used conversion accelerators at the present time, these compounds are unstable in the acid region. As a result, these com-pounds undergo spontaneous decomposition and are thereby consumed even when conversion treatment is not being run (storage period). The maintenance of a constant or prescribed Col ,cenl, ~lion of these compounds therefore requires continual replenishment to make up for the amount lost to this consumption.
It is also known that as a result of their oxidative activity and spontaneous decor"posilio" these nitrite salts partially convert to NOx gas, which diffuses into and pollutes the atmosphere.
When chlorate salts are used as conversion accelerators, chloride ions are produced as a decomposition product during conversion treatment and ac-cumulate in the conversion treatment bath. The corrosion resistance of themetal substrate is substantially impaired when even a trace of chloride ions from the conversion treatment bath remains on the surface of the metal workpiece. In addition, chlorate salts are ordinarily used in combination with another conversion accelerator, such as nitrite salts, and when used alone provide only a significantly reduced conversion reaction rate.
Stability in the conversion treatment bath is also a problem for the use of hydrogen peroxide as a conversion accelerator: Hydrogen peroxide is readily decomposed by oxygen dissolved in the conversion bath. In addition, hydrogen peroxide has a narrow optimal concentration range for conversion treatment, which makes it difficult to manage the conversion treatment bath.
When the dissolved concentration is too high, a powdery, poorly adherent conversion coating is deposited on the metal surface.
With regard to the use of nitrogenous organic compounds as conversion accelerators, the following problems are associated with the use of organic nitro compounds such as nitroguanine and sodium m-nitrobenzenesulfonate:
Nitroguanine, for example, has a low solubility in water and as a result cannot be formulated as a concentrate for addition to the conversion bath. It is also CA 02207179 1997-06-0~
W O96/17976 PCTÇUS95/15227 difficult to control the divalent iron ions concentration in the conversion bathusing nitroguanine because this compound has a weak capacity to oxidize the divalent iron ions. On the other hand, sodium m-nitrobenzenesulfonate provides a poor conversion performance when used by itself, and for this s reason this compound must ordinarily be used in combination with another, more powerful conversion accelerator. Moreover, its concentration management requires the use of large-scale measurement equipment, such as an ion chromatograph. Another problem with the use of organic nitro compounds is that the accumulation of these compounds and their .0 decomposition products in the conversion bath causes an increase in the c:l,e",ical oxygen demand ("COD") of the conversion treatment effluent, which unfavorably affects the environment.
Hydroxylamine compounds are another type of nitrogenous organic compounds used as conversion accelerators. These compounds, however, in order to achieve the best results, must be added to give concentrations of at least 1,000 parts per million by weight (hereinafter usually abbreviated as "ppm") in the conversion bath, giving rise to the possibility of a large and economically undesirable consumption of the conversion accelerator.
In addition, results have been reported from an inveslis~alion into the use of chromic acid and permanganate salts as conversion accelerators for zinc phosphate-based conversion treatment baths (Norio Sato, et al., Boshoku Gijutsu [English title: Corrosion Engineering], Volume 15, No. 5 (1966)).
These authors report that the formation of conversion coatings was not observed at concentrations of 5 millimoles per liter (hereinafter usually abbreviated as "mmol/L") or 10 mmol/L.
Many of the known conversion accelerators as described above are nit-rogenous compounds, and as such resist removal by chemical wastewater treatment techniques, so that in practice they are usually removed through microbiological treatments. However, even with the use of microbiological treatments, the elimination of high concentrations of these nitrogenous compounds is highly problematic, while a complete elimination cannot be achieved even at low concentrations. Nitrogenous compounds have recently CA 02207179 1997-06-0~
W O 96/17976 PCTrUS95/15227 come to be thought of as one factor in the eutrophication of bodies of water, and the discharge of nitrogenous compounds has therefore become subject to an increasingly strict regulatory atmosphere. in view of these environmental considerations, the development of a nitrogenous compound-free zinc s phosphate-based conversion bath would be highly desirable.
Another drawback to each of the above-described conversion accelerators is that, in order to obtain the thin, uniform, fine, and dense conversion coatings desired as underpaint coatings, the metal surface must in each case be conditioned by treatment with a colloidal titanium system .0 immediately prior to execution of the conversion treatment. In addition to the fact that treatment bath management is quite complicated in the case of surface conditioners, a surface-conditioning step also requires installation of the corresponding treatment facilities and expansion of the space devoted to treatment. As a result, strong demand has recently appeared for the ~s development of a conversion accelerator that is able to form high-qualityconversion coatings on metal surfaces even without the implementation of a surface-conditioning step.
Disclosure of the Invention Problems to Be Solved by the Invention The present invention seeks to solve the problems described above for conversion accelerators. More specifically, the present invention introduces a zinc phosphate-based conversion bath for metals and a metal surface treatment method which are able to deposil a fine, dense, and uniform zinc phosphate-type conversion coating on the surface of the metal substrate and which are able to 2S induce fine-crystal formation in the conversion coating.
Description of the Invention, Includinq Preferred Embodiments As a consequence of investigations focusing on organoperoxides within the realm of orga"ic oxidizing agents, the inventors discovered that fine, dense, and uniform zinc phosphale-type conversion coatings can be formed through the use of or~~anopero,cides soluble in the conversion bath as conversion accelerat-ors. The following discoveries were also made: organoperoxide conversion ac-celerators need not be used in combination with nitrate salts or another conver-CA 02207179 1997-06-0~
W O 96/17976 PCTrUS95115227 sion accelerator and thereby make possible the elimination of nitrogenous com-pounds from the conversion bath; the use of organoperoxide conversion acceler-ators yields fine dense and uniform crystals in the coating even without the ap-plication of a surface-conditioning treaL,I ,e, ll and the use of Ol y~"operoxide con-s version accelerators results in the formation of high-quality conversion coatings on metal substrates without being subject to narrow limitations of temperature zinc conce, Ill aLion and the like The present invention was developed as a result of these discoveries.
Since nitrogenous compounds are not included among the essential com-.0 ponents of conversion baths acco~;iir~y to the present invention treatment baths according to the present invention can also satisfy environmental regulations concerning the amount of nitrogenous compound in the effluent. One should note in this connection that there is very little risk of envil u"" ,e"lal damage when the nitrogen concentration in a conversion treatment bath is less than or equal to 20 ppm.
In specific terms then the present invention relates to an acidic zinc ~hos~hale-based conversion ll ~ aqueous liquid co~ osilio, 1 usually here-inafter called a "bath" for brevity for ll ealil ,9 metal substrates wherein said bath is ~:h~ erized in that it con~ins zinc ions and p hospl)~le ions as its main com-ponents and also contains organoperoxide(s) as a conversion accelerator.
The organoperoxide concenl,a~ion in said conversion treatment bath is preferably 50 to 1 500 ppm.
The zinc ~.hosphale-based treatment method according to the present in-vention for al-plil~tion to metal surfaces is ch~ractel i~ed by contacting the metal 2s surface with the above-described zinc phosphate-based conversion treatment bath accol dil ,9 to the present invention after the pH of the conversion bath has been a~ sted to 2.0 to 4Ø
Finally the described zinc pi ,ospl ,dle-based surface treatment accorcii, 19 to the invention method is preferabiy carried out by subjecting the preliminarily o 30 degreased surface of the metal to a water rinse and consecutively thereafter to the conversion treatment.
The app, u~riate range for zinc ions concer,ll clion in a bath according to CA 02207179 1997-06-0~
W O96/17976 PCTrUS95/15227 the invention will vary as a function of the service intended for the conversioncoating produced, but as a general matter the preferred range for this concen-tration is 0.5 to 15.0 g/L.
For example, the formation of a conversion coating with a coating weight of around 0.5 to 10.0 g/m2 is preferred when the conversion treatment bath according to the present invention is to be used to provide an underpaint coating for metals. The cGr,~sponding preferred zinc ions concentration range in the conversion bath will therefore be 0.5 to 5.0 g/L. When the zinc ions concenl,~lion falls below 0.5 g/L, the resulting zinc phosphate-type conversion coating will exhibit a reduced coverage ratio, which can cause an unsatisfactory post-paint coating adherence and an unsatisfactory post-paint corrosion resistance. Zinc ions concentrations in excess of 5.0 g/L cause a coarsening of the crystals in the coating, which can in particular cause a reduced post-paint coating adherence.
As another example, when the conversion treatment bath is to be used in support of the plastic working of metals, the formation of a thick conversioncoating with a coating weight of around 5.0 to 15.0 g/m2is preferred in order to produce a conversion film capable of following the plastic deformation of theworkpiece. In this case the preferred zinc ions concentration range in the conversion bath will be 5.0 to 15.0 g/L. It becomes difficult to obtain the prescribed coating weights for this application at zinc ions concentrations below 5.0 g/L. The coating weight no longer increases at above 15.0 g/L, which makes such values economically undesirable. The zinc ions can be provided by dissolving zinc oxide or zinc hydroxide in the acid component of the conversion bath or by dissolving a water-soluble zinc salt, such as the phosphate salt, sulfate salt, or the like, in the conversion bath.
The phosphate ions concentration in the conversion bath according to the present invention is preferably 5.0 to 30.0 g/L. Obtaining a normal conversion coating can become problematic at below 5.0 g/L. No additional benefits are obtained at above 30.0 g/L, which makes such values uneconomical. The phosphate ions can be generated by the addition of phosphoric acid or its aqueous solutions to the conversion bath or by -CA 02207179 1997-06-0~
dissolving a salt of phosphoric acid, such as the sodium, potassium, magnesium, zinc, or the like salt, in the conversion bath.
The zinc phosphate-based conversion treatment bath according to the present invention is an acidic aqueous solution whose pH preferably is from 2.0 to 4.0 and more preferably from about 2.5 to 3.5. In this pH region, ortho-phosphoric acid (H3PO4) exists in equilibrium primarily with dihydrogen phosphate ions (H2PO4), but also with much smaller amounts of hydrogen phosphate ions (HPo4-2) and phosphate ions (P043-); however, the concentrations specified herein as those of "phosphate ions" are intended to 0 include the stoichiometric equivalent as phosphate ions of any of the chemical species from undissociated orthophosphoric acid to completely ionized phosphate ions. The free acid content, measured as described in the examples below, of the compositions according to the invention preferably is at least, with increasing preference in the order given, 0.1, 0.3, 0.5, or 0.6 point and independently prt:rt:rably is not more than, with increasing preference in the order given, 1.5, 1.3, 1.2, 1.1, 1.0, or 0.9 point(s).
The or~anoperoxides used by the present invention can be classified into, for example, organoperoxides, such as ethyl hydroperoxide, isopropyl hy-droperoxide, tert-butyl hydroperoxide, tert-hexyl hydtoperoxide, diethyl peroxide, tert-butyl peroxymaleate, and the like, that contain a peroxy moiety without an ~ cent carbonyl group; and percarboxylic acid types such as per-acetic acid, monoperphthalic acid, persuccinic acid, and the like.
Organoperoxide molecules are preferably used at concentrations of 50 to 1,500 ppm in a conversion bath according to the invention. Acceleration of conversion film ru~ lion can become u~s~ r~ctory when the organoperoxide concenl~dliG" in the conversion bath is below 50 ppm. Accordingly, the organ-operoxide molecules present in the conversion bath according to the present invention preferably contain C, to C, alkyl moieties, because a low water sol-ubility is exhibited by organoperoxides containing aromatic or higher molecular weight alkyl moieties, and this can result in a failure to obtain a satisfactoryoxidizing activity. On the other hand, no additional effect is obtained at concentrations in excess of 1,500 ppm, and such values are therefore CA 02207179 1997-06-0~
W O96/17976 PCTrUS95/15227 uneconomical.
Because the conversion treatment bath according to the present invention also functions to induce fine-crystal formation on the part of the depositing zinc phosphate-type crystals, the instant conversion bath can produce a fine, dense, and uniform zinc phosphate-type conversion coating even in the absence of an immediately preceding surface-conditioning treatment for the specific purpose of inducing fine-crystal formation in the coating.
In addition, the conversion bath according to the present invention does ~o not require the addition of nitric acid, nitrous acid, an organic nitro compound, or the like, and thus can be formulated entirely free of nitrogenous compounds.
In this form it therefore offers the advantage of not requiring the inciusion ofa treatment step for nitrogenous compounds in the effiuent treatment process.
Nitrogenous compounds may be added to the conversion treatment bath 15 according to the present invention on an optional basis, but the nitrogen concentration is preferably held to no greater than 100 ppm and more preferably to 20 ppm or less.
Metal ions other than the zinc ions can be added to the zinc phosphate based conversion bath according to the present invention. These metal ions 20 can act as etchants in order to induce a uniform etch of the surface of the metal workpiece, or can act as paintability improvers when the conversion coating is being used as an underpaint coating.
Sllit~hle non-zinc metal ions are exemplified by nickel ions, manganese ions, cobalt ions, iron ions, magnesium ions, calcium ions, and so forth. Each 25 of these ions can be provided by ~issc' ~tion in the treatment bath of the oxide, hydroxide, carbonate, sulfate, phosphate, or the like, of the corresponding metal.
Fluoride ions or complex fluoride ions, e.g., fluosilicate ions, fluozirconate ions, and the like, can be used as etchant. These ions can be provided, for example, by dissolving in the conversion treatment bath one or more of the following fluorine compounds: hydrofluoric acid, fluosilicic acid, fluozirconic acid, fluotitanic acid, and the corresponding metal salts (e.g., CA 02207179 1997-06-0~
W O96117976 PCTrUS95115227 sodium, potassium, magnesium).
The following process steps preferably should be consecutively executed in the sequence given in order to form a conversion coating on metal surfaces using a zinc phosphate based conversion bath according to the present invention: alkaline degreasing, a water rinse, treatment with the zinc phosphate-based conversion bath, and a water rinse. The degreasing and water rinse processes may themselves each be implemented as multistage plucesses. A d0ioni~d water rinse is preferably used for the final water rinse when the conversion coating will be used as an underpaint coating. Moreover, 0 when the conversion coating is produced on a metal surface for use as an underpaint CGdlillg, it is preferred that the conversion treatment be immediately preceded by a surface conditioning process using a colloidal titanium-containing surface conditioner for the purpose of inducing fine-cr,vstal formation in the coating.
.s Metals subjected to the above-described conversion treatment can be painted after the final water rinse as described above or after a drying step that follows the final water rinse.
When plastic working is the intended service for the conversion film formed on a metal substrate using the conversion bath according to the present invention, after the above-described degreasing and water rinse the metal workpiece is preferably subjected to a pickling step for purposes of descaling. Again with reference to production of the conversion film for plasticworking service, the lubricity of the coating can be improved even further by a soap ~ lmellL (lubrication ~ dl",ent) after formation of the conversion film.
Surface l~ l",ent using the zinc phosphate-based conversion bath ac-co,di"y to the present invention is generally executed by immersion, spraying, or a combination thereof. When the conversion film is intended as an underpaint coating, the desired coating can be, and preferably is, formed by conversion treatment at a treatment temperature from about room temperature to about 60 ~C and at a treatment time from about 0.5 minute to about ~
minutes. When the conversion film is intended for plastic working service, the desired coating can be, and preferably is, formed by conversion treatment at CA 02207179 1997-06-0~
W O96tl7976 PCT~US95/15227 a treatment temperature from about 50 ~C to about 90 ~C and at a treatment time from about 1 minute to about 15 minutes.
The invention will be explained in greater detail below with reference to the following working and comparative examples of actual treatment. The scope of the present invention is in no way limited by these examples.
Exampies The test materials were (1 ) 0.8 mm-thick cold-rolled steel sheets (SPCC-SD, abbreviated below as "SPC") and (2) galvanized steel sheets (abbreviated below as "plated") prepared by the zinc electFoplating (20 g/m2) of the aforemen-tioned cold-rolled steel sheets. These were in each case cut to 70 x 150 mm and subjected to treatment in the working and co"~F,ar~ /e examples described be-low.
The following treatment process steps, which are a typical example of treatment for the purpose of producing an underpaint coating, were used in the ,s working and comparative examples:
(1) degreasing (alkaline degreaser, brand name: FINECLEANERTM L4460 from Nihon Parkerizing Company, Limited, 20 g/L of constituent A, 12 glL of constituent B);
43 C, 120 seconds, immersion;
20 (2) water rinse (tap water);
ambient temperature, 30 seconds, spray;
Description ZINC PHOSPHATE CONVERSION COATING COMPOSITION AND PROCESS
Technical Field This invention relates to zinc phosphate-based conversion treatment baths which can be applied to a variety of metal substrates, for example, steel, steelsheet, galvanized steel sheet, and the like. More particularly, this invention re-lates to a zinc phosphate-based conversion bath and to a surface treatment method that are able to form a fine, dense, and uniform conversion coating on metal surfaces and that are ~Iso able to induce fine-crystal formation in the con-version coating.
Background Art ~o The execution of a zinc phosphate-based conversion treatment on various metals prior to the coating or plastic working thereof is known at present for the purpose of improving the paint adherence and post-paint corrosion resistance and improving the lubrication during plastic working.
The conversion treatment baths used for zinc phosphate-based conver-15 sion treatment are essentially acidic aqueous solutions that contain zinc ions, phosphate ions, and oxidizing agent(s). Nitrite salts, chlorate salts, hydrogen peroxide, organic nitro compounds, hydroxylamine, and the like, are ordinarily co"sidered for this oxidizing agent. These oxidizing agents are typically calledconversion "accelerators" bec~ se they ~unction to accelerate the conversion re-20 actions. Nitrate salts may be prese, IL ~n conversion baths, but--because, in theco,)cer,l,cliu, ,s usually presenl in zinc phos~chate-based conversion baths, nitrate ions do not exercise an oxidizing activity sufficient to convert ferrous ions sub-stantially completely to ferric ions--nitrate ions must be distinguished from the conversion accelerators.
One important role of conversion accelerators during the zinc phosphate based conversion treatment of ferriferous metals is to oxidize the divalent ironions eluting into the conversion bath to trivalent iron ions. For example, the conversion reactions are inhibited when divalent iron ions accumulate in the conversion bath during the continuous conversion treatment of fe" irerous metals, 30 and the role of the conversion accelerator in inhibiting this accumulation of CA 02207179 1997-06-0~
W O96/17976 PCTrUS95/15227 divalent iron ions is thus crucial.
However, each of these already kno~n conversion accelerators is associ-ated with problems that must be addressed. For example, in the case of the ni-trite salts, which are the most widely used conversion accelerators at the present time, these compounds are unstable in the acid region. As a result, these com-pounds undergo spontaneous decomposition and are thereby consumed even when conversion treatment is not being run (storage period). The maintenance of a constant or prescribed Col ,cenl, ~lion of these compounds therefore requires continual replenishment to make up for the amount lost to this consumption.
It is also known that as a result of their oxidative activity and spontaneous decor"posilio" these nitrite salts partially convert to NOx gas, which diffuses into and pollutes the atmosphere.
When chlorate salts are used as conversion accelerators, chloride ions are produced as a decomposition product during conversion treatment and ac-cumulate in the conversion treatment bath. The corrosion resistance of themetal substrate is substantially impaired when even a trace of chloride ions from the conversion treatment bath remains on the surface of the metal workpiece. In addition, chlorate salts are ordinarily used in combination with another conversion accelerator, such as nitrite salts, and when used alone provide only a significantly reduced conversion reaction rate.
Stability in the conversion treatment bath is also a problem for the use of hydrogen peroxide as a conversion accelerator: Hydrogen peroxide is readily decomposed by oxygen dissolved in the conversion bath. In addition, hydrogen peroxide has a narrow optimal concentration range for conversion treatment, which makes it difficult to manage the conversion treatment bath.
When the dissolved concentration is too high, a powdery, poorly adherent conversion coating is deposited on the metal surface.
With regard to the use of nitrogenous organic compounds as conversion accelerators, the following problems are associated with the use of organic nitro compounds such as nitroguanine and sodium m-nitrobenzenesulfonate:
Nitroguanine, for example, has a low solubility in water and as a result cannot be formulated as a concentrate for addition to the conversion bath. It is also CA 02207179 1997-06-0~
W O96/17976 PCTÇUS95/15227 difficult to control the divalent iron ions concentration in the conversion bathusing nitroguanine because this compound has a weak capacity to oxidize the divalent iron ions. On the other hand, sodium m-nitrobenzenesulfonate provides a poor conversion performance when used by itself, and for this s reason this compound must ordinarily be used in combination with another, more powerful conversion accelerator. Moreover, its concentration management requires the use of large-scale measurement equipment, such as an ion chromatograph. Another problem with the use of organic nitro compounds is that the accumulation of these compounds and their .0 decomposition products in the conversion bath causes an increase in the c:l,e",ical oxygen demand ("COD") of the conversion treatment effluent, which unfavorably affects the environment.
Hydroxylamine compounds are another type of nitrogenous organic compounds used as conversion accelerators. These compounds, however, in order to achieve the best results, must be added to give concentrations of at least 1,000 parts per million by weight (hereinafter usually abbreviated as "ppm") in the conversion bath, giving rise to the possibility of a large and economically undesirable consumption of the conversion accelerator.
In addition, results have been reported from an inveslis~alion into the use of chromic acid and permanganate salts as conversion accelerators for zinc phosphate-based conversion treatment baths (Norio Sato, et al., Boshoku Gijutsu [English title: Corrosion Engineering], Volume 15, No. 5 (1966)).
These authors report that the formation of conversion coatings was not observed at concentrations of 5 millimoles per liter (hereinafter usually abbreviated as "mmol/L") or 10 mmol/L.
Many of the known conversion accelerators as described above are nit-rogenous compounds, and as such resist removal by chemical wastewater treatment techniques, so that in practice they are usually removed through microbiological treatments. However, even with the use of microbiological treatments, the elimination of high concentrations of these nitrogenous compounds is highly problematic, while a complete elimination cannot be achieved even at low concentrations. Nitrogenous compounds have recently CA 02207179 1997-06-0~
W O 96/17976 PCTrUS95/15227 come to be thought of as one factor in the eutrophication of bodies of water, and the discharge of nitrogenous compounds has therefore become subject to an increasingly strict regulatory atmosphere. in view of these environmental considerations, the development of a nitrogenous compound-free zinc s phosphate-based conversion bath would be highly desirable.
Another drawback to each of the above-described conversion accelerators is that, in order to obtain the thin, uniform, fine, and dense conversion coatings desired as underpaint coatings, the metal surface must in each case be conditioned by treatment with a colloidal titanium system .0 immediately prior to execution of the conversion treatment. In addition to the fact that treatment bath management is quite complicated in the case of surface conditioners, a surface-conditioning step also requires installation of the corresponding treatment facilities and expansion of the space devoted to treatment. As a result, strong demand has recently appeared for the ~s development of a conversion accelerator that is able to form high-qualityconversion coatings on metal surfaces even without the implementation of a surface-conditioning step.
Disclosure of the Invention Problems to Be Solved by the Invention The present invention seeks to solve the problems described above for conversion accelerators. More specifically, the present invention introduces a zinc phosphate-based conversion bath for metals and a metal surface treatment method which are able to deposil a fine, dense, and uniform zinc phosphate-type conversion coating on the surface of the metal substrate and which are able to 2S induce fine-crystal formation in the conversion coating.
Description of the Invention, Includinq Preferred Embodiments As a consequence of investigations focusing on organoperoxides within the realm of orga"ic oxidizing agents, the inventors discovered that fine, dense, and uniform zinc phosphale-type conversion coatings can be formed through the use of or~~anopero,cides soluble in the conversion bath as conversion accelerat-ors. The following discoveries were also made: organoperoxide conversion ac-celerators need not be used in combination with nitrate salts or another conver-CA 02207179 1997-06-0~
W O 96/17976 PCTrUS95115227 sion accelerator and thereby make possible the elimination of nitrogenous com-pounds from the conversion bath; the use of organoperoxide conversion acceler-ators yields fine dense and uniform crystals in the coating even without the ap-plication of a surface-conditioning treaL,I ,e, ll and the use of Ol y~"operoxide con-s version accelerators results in the formation of high-quality conversion coatings on metal substrates without being subject to narrow limitations of temperature zinc conce, Ill aLion and the like The present invention was developed as a result of these discoveries.
Since nitrogenous compounds are not included among the essential com-.0 ponents of conversion baths acco~;iir~y to the present invention treatment baths according to the present invention can also satisfy environmental regulations concerning the amount of nitrogenous compound in the effluent. One should note in this connection that there is very little risk of envil u"" ,e"lal damage when the nitrogen concentration in a conversion treatment bath is less than or equal to 20 ppm.
In specific terms then the present invention relates to an acidic zinc ~hos~hale-based conversion ll ~ aqueous liquid co~ osilio, 1 usually here-inafter called a "bath" for brevity for ll ealil ,9 metal substrates wherein said bath is ~:h~ erized in that it con~ins zinc ions and p hospl)~le ions as its main com-ponents and also contains organoperoxide(s) as a conversion accelerator.
The organoperoxide concenl,a~ion in said conversion treatment bath is preferably 50 to 1 500 ppm.
The zinc ~.hosphale-based treatment method according to the present in-vention for al-plil~tion to metal surfaces is ch~ractel i~ed by contacting the metal 2s surface with the above-described zinc phosphate-based conversion treatment bath accol dil ,9 to the present invention after the pH of the conversion bath has been a~ sted to 2.0 to 4Ø
Finally the described zinc pi ,ospl ,dle-based surface treatment accorcii, 19 to the invention method is preferabiy carried out by subjecting the preliminarily o 30 degreased surface of the metal to a water rinse and consecutively thereafter to the conversion treatment.
The app, u~riate range for zinc ions concer,ll clion in a bath according to CA 02207179 1997-06-0~
W O96/17976 PCTrUS95/15227 the invention will vary as a function of the service intended for the conversioncoating produced, but as a general matter the preferred range for this concen-tration is 0.5 to 15.0 g/L.
For example, the formation of a conversion coating with a coating weight of around 0.5 to 10.0 g/m2 is preferred when the conversion treatment bath according to the present invention is to be used to provide an underpaint coating for metals. The cGr,~sponding preferred zinc ions concentration range in the conversion bath will therefore be 0.5 to 5.0 g/L. When the zinc ions concenl,~lion falls below 0.5 g/L, the resulting zinc phosphate-type conversion coating will exhibit a reduced coverage ratio, which can cause an unsatisfactory post-paint coating adherence and an unsatisfactory post-paint corrosion resistance. Zinc ions concentrations in excess of 5.0 g/L cause a coarsening of the crystals in the coating, which can in particular cause a reduced post-paint coating adherence.
As another example, when the conversion treatment bath is to be used in support of the plastic working of metals, the formation of a thick conversioncoating with a coating weight of around 5.0 to 15.0 g/m2is preferred in order to produce a conversion film capable of following the plastic deformation of theworkpiece. In this case the preferred zinc ions concentration range in the conversion bath will be 5.0 to 15.0 g/L. It becomes difficult to obtain the prescribed coating weights for this application at zinc ions concentrations below 5.0 g/L. The coating weight no longer increases at above 15.0 g/L, which makes such values economically undesirable. The zinc ions can be provided by dissolving zinc oxide or zinc hydroxide in the acid component of the conversion bath or by dissolving a water-soluble zinc salt, such as the phosphate salt, sulfate salt, or the like, in the conversion bath.
The phosphate ions concentration in the conversion bath according to the present invention is preferably 5.0 to 30.0 g/L. Obtaining a normal conversion coating can become problematic at below 5.0 g/L. No additional benefits are obtained at above 30.0 g/L, which makes such values uneconomical. The phosphate ions can be generated by the addition of phosphoric acid or its aqueous solutions to the conversion bath or by -CA 02207179 1997-06-0~
dissolving a salt of phosphoric acid, such as the sodium, potassium, magnesium, zinc, or the like salt, in the conversion bath.
The zinc phosphate-based conversion treatment bath according to the present invention is an acidic aqueous solution whose pH preferably is from 2.0 to 4.0 and more preferably from about 2.5 to 3.5. In this pH region, ortho-phosphoric acid (H3PO4) exists in equilibrium primarily with dihydrogen phosphate ions (H2PO4), but also with much smaller amounts of hydrogen phosphate ions (HPo4-2) and phosphate ions (P043-); however, the concentrations specified herein as those of "phosphate ions" are intended to 0 include the stoichiometric equivalent as phosphate ions of any of the chemical species from undissociated orthophosphoric acid to completely ionized phosphate ions. The free acid content, measured as described in the examples below, of the compositions according to the invention preferably is at least, with increasing preference in the order given, 0.1, 0.3, 0.5, or 0.6 point and independently prt:rt:rably is not more than, with increasing preference in the order given, 1.5, 1.3, 1.2, 1.1, 1.0, or 0.9 point(s).
The or~anoperoxides used by the present invention can be classified into, for example, organoperoxides, such as ethyl hydroperoxide, isopropyl hy-droperoxide, tert-butyl hydroperoxide, tert-hexyl hydtoperoxide, diethyl peroxide, tert-butyl peroxymaleate, and the like, that contain a peroxy moiety without an ~ cent carbonyl group; and percarboxylic acid types such as per-acetic acid, monoperphthalic acid, persuccinic acid, and the like.
Organoperoxide molecules are preferably used at concentrations of 50 to 1,500 ppm in a conversion bath according to the invention. Acceleration of conversion film ru~ lion can become u~s~ r~ctory when the organoperoxide concenl~dliG" in the conversion bath is below 50 ppm. Accordingly, the organ-operoxide molecules present in the conversion bath according to the present invention preferably contain C, to C, alkyl moieties, because a low water sol-ubility is exhibited by organoperoxides containing aromatic or higher molecular weight alkyl moieties, and this can result in a failure to obtain a satisfactoryoxidizing activity. On the other hand, no additional effect is obtained at concentrations in excess of 1,500 ppm, and such values are therefore CA 02207179 1997-06-0~
W O96/17976 PCTrUS95/15227 uneconomical.
Because the conversion treatment bath according to the present invention also functions to induce fine-crystal formation on the part of the depositing zinc phosphate-type crystals, the instant conversion bath can produce a fine, dense, and uniform zinc phosphate-type conversion coating even in the absence of an immediately preceding surface-conditioning treatment for the specific purpose of inducing fine-crystal formation in the coating.
In addition, the conversion bath according to the present invention does ~o not require the addition of nitric acid, nitrous acid, an organic nitro compound, or the like, and thus can be formulated entirely free of nitrogenous compounds.
In this form it therefore offers the advantage of not requiring the inciusion ofa treatment step for nitrogenous compounds in the effiuent treatment process.
Nitrogenous compounds may be added to the conversion treatment bath 15 according to the present invention on an optional basis, but the nitrogen concentration is preferably held to no greater than 100 ppm and more preferably to 20 ppm or less.
Metal ions other than the zinc ions can be added to the zinc phosphate based conversion bath according to the present invention. These metal ions 20 can act as etchants in order to induce a uniform etch of the surface of the metal workpiece, or can act as paintability improvers when the conversion coating is being used as an underpaint coating.
Sllit~hle non-zinc metal ions are exemplified by nickel ions, manganese ions, cobalt ions, iron ions, magnesium ions, calcium ions, and so forth. Each 25 of these ions can be provided by ~issc' ~tion in the treatment bath of the oxide, hydroxide, carbonate, sulfate, phosphate, or the like, of the corresponding metal.
Fluoride ions or complex fluoride ions, e.g., fluosilicate ions, fluozirconate ions, and the like, can be used as etchant. These ions can be provided, for example, by dissolving in the conversion treatment bath one or more of the following fluorine compounds: hydrofluoric acid, fluosilicic acid, fluozirconic acid, fluotitanic acid, and the corresponding metal salts (e.g., CA 02207179 1997-06-0~
W O96117976 PCTrUS95115227 sodium, potassium, magnesium).
The following process steps preferably should be consecutively executed in the sequence given in order to form a conversion coating on metal surfaces using a zinc phosphate based conversion bath according to the present invention: alkaline degreasing, a water rinse, treatment with the zinc phosphate-based conversion bath, and a water rinse. The degreasing and water rinse processes may themselves each be implemented as multistage plucesses. A d0ioni~d water rinse is preferably used for the final water rinse when the conversion coating will be used as an underpaint coating. Moreover, 0 when the conversion coating is produced on a metal surface for use as an underpaint CGdlillg, it is preferred that the conversion treatment be immediately preceded by a surface conditioning process using a colloidal titanium-containing surface conditioner for the purpose of inducing fine-cr,vstal formation in the coating.
.s Metals subjected to the above-described conversion treatment can be painted after the final water rinse as described above or after a drying step that follows the final water rinse.
When plastic working is the intended service for the conversion film formed on a metal substrate using the conversion bath according to the present invention, after the above-described degreasing and water rinse the metal workpiece is preferably subjected to a pickling step for purposes of descaling. Again with reference to production of the conversion film for plasticworking service, the lubricity of the coating can be improved even further by a soap ~ lmellL (lubrication ~ dl",ent) after formation of the conversion film.
Surface l~ l",ent using the zinc phosphate-based conversion bath ac-co,di"y to the present invention is generally executed by immersion, spraying, or a combination thereof. When the conversion film is intended as an underpaint coating, the desired coating can be, and preferably is, formed by conversion treatment at a treatment temperature from about room temperature to about 60 ~C and at a treatment time from about 0.5 minute to about ~
minutes. When the conversion film is intended for plastic working service, the desired coating can be, and preferably is, formed by conversion treatment at CA 02207179 1997-06-0~
W O96tl7976 PCT~US95/15227 a treatment temperature from about 50 ~C to about 90 ~C and at a treatment time from about 1 minute to about 15 minutes.
The invention will be explained in greater detail below with reference to the following working and comparative examples of actual treatment. The scope of the present invention is in no way limited by these examples.
Exampies The test materials were (1 ) 0.8 mm-thick cold-rolled steel sheets (SPCC-SD, abbreviated below as "SPC") and (2) galvanized steel sheets (abbreviated below as "plated") prepared by the zinc electFoplating (20 g/m2) of the aforemen-tioned cold-rolled steel sheets. These were in each case cut to 70 x 150 mm and subjected to treatment in the working and co"~F,ar~ /e examples described be-low.
The following treatment process steps, which are a typical example of treatment for the purpose of producing an underpaint coating, were used in the ,s working and comparative examples:
(1) degreasing (alkaline degreaser, brand name: FINECLEANERTM L4460 from Nihon Parkerizing Company, Limited, 20 g/L of constituent A, 12 glL of constituent B);
43 C, 120 seconds, immersion;
20 (2) water rinse (tap water);
ambient temperature, 30 seconds, spray;
(3) surface conditioning (colloidal titanium surface conditioner, brand name:
PREPALENE~ ZN from Nihon Parkerizing Company, Limited, 1 g/L
aqueous solution);
2s ambient temperature, 30 seconds, spray;
PREPALENE~ ZN from Nihon Parkerizing Company, Limited, 1 g/L
aqueous solution);
2s ambient temperature, 30 seconds, spray;
(4) zinc phosphate-based conversion treatment (as described below for the individual working and comparative examples);
43 C, 120 seconds, immersion;
43 C, 120 seconds, immersion;
(5) water rinse (tap water);
ambient temperature, 30 seconds, spray;
ambient temperature, 30 seconds, spray;
(6) deionized water rinse (deionized water, conductivity = 0.2 microS/cm) CA 02207179 1997-06-0~
ambient temperature, 20 seconds, spray;
ambient temperature, 20 seconds, spray;
(7) drain and dry;
hot air at 110 ~C, 180 seconds, except that the surface-conditioning step was not carried out in Examples 5 and 7 or in Comparative Example 3, and in these cases the zinc phosphate-based conversion treatment step (4) was therefore carried out directly after the degreasing (1) and ensuing water rinse (2) steps.
The free acidity in the zinc phosphate-based conversion baths in Ex-arnples 1 to 8 and Comparative Examples 1 to 4 was adjusted to specific values using sodium hydroxide. The free acidity was measured by titrating 10 milliliters (hereinafter usually abbreviated as "mL") of the particular treatment bath to neutrality with 0.1 N aqueous sodium hydroxide, using bromophenol blue as the indicator. The number of mL of the 0.1 N aqueous sodium hydroxide required for the color change from yellow to blue was determined and is reported as "points" of free acidity. The fluoride ions concentration in the conversion bath was measured using a fluoride sensitive electrode.
The coating weight was measured as follows: The weight (W1) in grams of the treated sheet after conversion treatment was first measured, and the treated sheet was then subjected to a film stripping treatment using the stripping solution and stripping conditions reported below. The weight of the stripped sheet was measured to give W2 in grams, and the coating weight was calcul~ter~ from the following equation:
Coating weight (in g/m2) = (W1 - W2)/0.021.
Treatment for cold-rolled steel sheets stripping solution: 5 % aqueous chromic acid solution stripping conditions: 75 ~C, 15 minutes, immersion Treatment for qalvanized steel sheets stripping solution: 2 % by weight (hereinafter usually abbreviated as "wt%") of ammonium dichromate + 49 wt% of 28 wt% aqueous solution of ammonia + 49 wt%
pure water stripping conditions: ambient temperature, 15 minutes, immersion.
CA 02207179 1997-06-0~
The appearance of the coatings was inspected visually, and the mor-phology and size of the grains in the conversion coating was evaluated by inspection with a scanning electron microscope (SEM).
Example 1 5 Composition of the conversion bath phosphate ions : 15 g/L (from addition of 75% phosphoric acid) zinc ions : 1.3 g/L (from addition of zinc oxide) nickel ions : 1.0 g/L (from addition of nickel carbonate) manganese ions : 0.5 g/L (from addition of manganese carbonate) fluoride ions : 100 ppm (from addition of 55 % hydrofluoric acid) 450 ppm of tert-butyl hydroperoxide (organoperoxide component) was added to the conversion bath with the above composition, and the free acidity of the conversion bath was then adjusted to 0.9 point. A cold-rolled steel test sheetpon was subjected first to the colloidal titanium surface-conditioning treatment and then to conversion treatment (conversion temperature = 43 ~C, treatment time = 120 seconds) using the above-described conversion bath.
The resulting conversion coating weight was 1.2 g/m2. The coating crystals were plates with an average grain size of 6 micrometers. The conversion coating was grayish black and was uniform, fine, and dense.
Example 2 A galvanized steel test sheet was subjected first to the same surface conditioning ll~l",el)t as in E)~dulple 1 and then to conversion treatment usingthe same conversion treatment bath as in Example 1. The resulting conversion coating weight was 2.8 g/mZ. The crystals were plates with an 2s average grain size of 4 micrometers. The conversion coating was grayish white and was uniform, fine, and dense.
ExamPle 3 A cold-rolled steel test sheet was subjected first to the same sur-face-condilioning treatment as in Example 1 and then to conversion treatment using the same conversion treatment bath as in Example 1, except that the or-ganoperoxide addition consisted of 80 ppm tert-butyl hydroperoxide and the free acidity was adjusted to 0.6 point. The resulting conversion coating weight CA 02207179 1997-06-0~
W 096/17976 PCT~US95/lS227 was 0.9 g/m2. The coating crystals were plates with an average grain size of 8 micrometers. The conversion coating was grayish black and was uniform, fine, and dense.
ExamPle 4 A cold-rolled steel test sheet was subjected first to the same surface conditioning l,e~l",ent as in Example 1 and then to conversion treatment using the same conversion treatment bath as in Example 1, except that 1,200 ppm of tert-butyl hydroperoxide was added as the organoperoxide and sufficient 65.5% nitric acid was added to give a nitrogen component content of 500 ppm.
The free acidity of the conversion bath was adjusted to 0.9 point. The resulting conversion coating weight was 1.1 g/m2. The coating crystals were plates with an average grain size of 7 micrometers. The conversion coating was grayish black and was uniform, fine, and dense.
ExamPle 5 ~6 A ~ld-rolled s~.eel t~:st sheei ~rs suojected to conversion treatment as in Example 1, except that there was no surface-conditioning treatment and only 400 ppm of tert-hexyl hydroperoxide was added as the organoperoxide.
The free acidity was adjusted to 0.9 point. The resulting conversion coating weight was 1.0 g/m2. The coating crystals were plates with an average grain size of 6 micrometers. The conversion coating was grayish black and was uniform, fine, and dense.
ExamPle 6 A cold-rolled steel test sheet was subjected first to the same surface condilioning treatment as in Example 1 and then to conversion treatment using z5 the same conversion treatment bath as in Example 1, except that 100 ppm of peracetic acid was added as the organoperoxide, and the free acidit~ was ad-justed to 0.6 point. The resulting conversion coali"g weight was 1.3 glm2. The coating crystals were plates with an average grain size of 10 micrometers.
The conversion coating was grayish black and was uniform, fine, and dense.
Example 7 A cold-rolled steel test sheet was subjected to conversion treatment us-ing the same conversion bath as in Example 1, except that the surface condi-CA 02207179 1997-06-0~
W O 96/17976 PCTrUS95/15227 tioning treatment was not used, 500 ppm of tert-butyl hydroperoxide was added as the organoperoxide, and the free acidity was adjusted to 0.6 point.
The resulting conversion coating weight was 1.1 g/m2. The coating crystals were plates with an average grain size of 10 micrometers. The conversion~ coating was grayish black and was uniform, fine, and dense.
ExamPle 8 Composition of the conversion bath phosphate ions : 15 g/L (from addition of 75 % phosphoric acid) zinc ions : 1.3 g/L (from addition of zinc oxide) ~0 nickel ions : 1.0 g/L (from addition of nickel nitrate) manganese ions : 0.5 g/L (from addition of manganese carbonate) fluoride ions : 100 ppm (from addition of 55 % hydrofluoric acid) nitrate ions : 7.2 g/L (from addition of sodium nitrate and nickel ni-trate) (nitrogen concentration = 1.4 g/L).
450 ppm of tert-butyl hydroperoxide (organoperoxide component) was added to the conversion bath with the above composition, and the free acidity of the conversion bath was then adjusted to 0.9 point. A cold-rolled steel test sheetpon was subjected first to the colloidal titanium surface-conditioning treatment and then to conversion treatment (conversion temperature = 43~C, treatment time = 120 seconds) using the above-described conversion bath.
The resulting conversion coating weight was 1.1 g/m2. The coating crystals were plates with an average grain size of 5 micrometers. The conversion coating was grayish black and was uniform, fine, and dense.
Comparative Example 1 A cold-rolled steel test sheet was subjected to the same surface condi-tioning treatment as in Example 1 and was then submitted to the same conver-sion treatment as in Example 1, except that the organoperoxide addition con-sisted of 5 ppm of tert-butyl hydroperoxide. The conversion coating weight was 0.5 g/m2, and the development of yellow rust was observed.
Comparative ExamPle 2 A galvanized steel test sheet was subjected to conversion treatment as in Example 1, except that the organoperoxide addition consisted of 5 ppm of CA 02207l79 l997-06-0~
Wo 96/17976 PCT/US95/15227 tert-butyl hydroperoxide. The conversion coating weight was 0.9 g/m2 the average grain size was 15 micrometers and the coating was sparse.
Com~arative Example 3 A cold-rolled steel test sheet was subjected to conversion treatment as in i-=~(dlllplC 8 except that there was no surface-col1diliol ~ing treatment and 150 ppm of nitrite salt was added to the conversion bath in place of the organoper-oxide. The conversion coating weight was 0.1 g/m2 whici1 indicated that almost no conversion coating deposition had occurred. Yellow rust had developed over the entire surface.
.0 ComParative Example 4 A cold-rolled steel test sheet was subjected to conversion treatment as in Example 1 except that sodium chlorate was added to the conversion bath in place of the organoperoxide. The sodium chlorate was added to give a chlorate ions conce~ liol) of 1.5 g/L. The conversion coating weight was 0.9 9/m2. The codlil,~ crystals were columnar and the average grain size was 15 ~,i run,eters. The conversion codlill~ was sparsely deposited and yellow rust was observed.
The co"dilio"s and results of these examples are summarized in Table 1 below.
The organoperoxide conce"lrdlions used in Examples 1 to 8 were 50 to 1 500 ppm. It was thereby cler"onsl, dlad that this concentration range produceda good~uality conversion coating on cold-rolled steel sheet as well as galvan-ized steel sheet. A uniform dense and fine coali"g was obldi"ed even when the surface conditioning treatment was not used.
In co, lllasl Co",pdlalive Examples 1 and 2 used ûrgdl ,oper~xide concen-lrdlio"s beiow 50 ppm and it was found that in these cases the oxidation activity by the conversion accelerator was in~de~u~te~ resulting in the ~leposilion of scat-tered coating crystals. The uniformity of the coating on the basis metal was therefore diminished.
Co",pa,ali"e i~a,r,ples 3 and 4 used non-o,gci~operoxide conversion ac-cclerdlor~. In Colllpdldlive i-xample 3 a nitrite salt was used as the conversion accelerator and no surface~, ,.liliûr,i,)g 1, edll "ent was carried out. It was found W O96/17976 PCT~US95/15227 Examples Substrate Phos- Zinc Nitrogen Surface Oxidizing And phate Ions,Concen- Condi- Agent Colllpal~ re Ions, g/Ltration, tioning *
Examples g/L ppm Example 1 SPC 15 1.3 0 yes a F.x~mple 2 plated 15 1.3 0 yes a Example 3 SPC 15 1.3 0 yes a Example 4 SPC 15 1.3 500 yes a Example 5 SPC 15 1.3 0 no b Example 6 SPC 15 1.3 0 yes c Example 7 SPC 15 1.3 0 no a Example 8 SPC 15 1.3 1400 yes a Co~ Li~re Example 1 SPC 15 1.3 0 yes a Collll~al ~Li~e Example 2 plated 15 1.3 0 yes a Colllpal~ e Fx~mrle 3 SPC 15 1.3 1400 no d Comparative Fx~mrle 4 SPC 15 1.3 0 yes e grayish Fx~mrle 1 450 0 9 1.2 black plates 6 grayish Fx~mple 2 450 0.9 2.8 white plates 4 grayish F.x~mrle 3 80 0.6 0 9 black plates 8 grayish Example 4 1200 0.9 1.1 black plates 7 *Type of oxi~i~in~ agents added:
a tert-butyl hydroperoxide b tert-hexyl hydlopero~ide c peracetic acid d nitriteions e chlorate ions ... Table I is conVnued on V7e nex~ page ...
wo 96/17976 PCT/Us95/15227 Examples Substrate Phos- ZincMtrogen Surface Oxidizing And phate Ions,Concen- Condi- Agent Co~ al~;ve Ions, g/Ltration, tioning *
F~mrle~ g/L ppm grayish F.Y~mrle 5 400 0-9 1.0 black plates 6 grayish Example 6 100 0.6 1.3 black plates 10 grayish Example 7 500 0.6 1.1 black plates 10 grayish Example 8 450 0.9 1.1 black plates 5 yellow Col~lp~Live lUSt Example 1 5 0.9 0.5appeared columnar 13 Co-l.p~ ive sparse Example 2 ~ 0.9 0.9 coating columnar 15 yellow C~o.. pal ~ive rust Example 3 150 0.9 0.1appeared granular 80 C~ Li~e sparse Example 4 1500 0.9 0.9 coating col-lmnQr 15 that in this case conversion coating deposition was entirely absent.
A chlorate salt was used by itself as the conversion accelerator in Com-parative Example 4. It was found that in this case the conversion reaction rate was sul~sLdrllially slowed.
Benefits of the Invention The zinc phosphate-based conversion bath according to the present in-vention for application to metal substrates contains a,~,pro,u, iate concentrations of o~ uanoperuxide as conversion accelerator. In consequence thereof, this bath yields uniform, fine, and dense conversion coatings with coating weights ~o a~ uru~ul iale for the intended applications. This bath at the same time also acts to induce fine crystal formation in the conversion coating. As a result, the bath has such good effects that a surface-conditioning treatment is no longer a CA 02207179 1997-06-0~
W O 96117976 PCT~US95/15227 necessity.
The organoperoxides used by the present invention react under mild con-ditions and are more stable than the generally used inorganic accelerators, and as a consequence have very good economic attributes. Since the presence of s nitrogenous compounds in the conversion treatment bath is also no longer a ne-cessity, environmental regulations relating to the levels of ni~, oge~ ,ous compound discharge can now be fully satisfied, and on this point the conversion bath ac-cording to the present invention represents a major practical development.
hot air at 110 ~C, 180 seconds, except that the surface-conditioning step was not carried out in Examples 5 and 7 or in Comparative Example 3, and in these cases the zinc phosphate-based conversion treatment step (4) was therefore carried out directly after the degreasing (1) and ensuing water rinse (2) steps.
The free acidity in the zinc phosphate-based conversion baths in Ex-arnples 1 to 8 and Comparative Examples 1 to 4 was adjusted to specific values using sodium hydroxide. The free acidity was measured by titrating 10 milliliters (hereinafter usually abbreviated as "mL") of the particular treatment bath to neutrality with 0.1 N aqueous sodium hydroxide, using bromophenol blue as the indicator. The number of mL of the 0.1 N aqueous sodium hydroxide required for the color change from yellow to blue was determined and is reported as "points" of free acidity. The fluoride ions concentration in the conversion bath was measured using a fluoride sensitive electrode.
The coating weight was measured as follows: The weight (W1) in grams of the treated sheet after conversion treatment was first measured, and the treated sheet was then subjected to a film stripping treatment using the stripping solution and stripping conditions reported below. The weight of the stripped sheet was measured to give W2 in grams, and the coating weight was calcul~ter~ from the following equation:
Coating weight (in g/m2) = (W1 - W2)/0.021.
Treatment for cold-rolled steel sheets stripping solution: 5 % aqueous chromic acid solution stripping conditions: 75 ~C, 15 minutes, immersion Treatment for qalvanized steel sheets stripping solution: 2 % by weight (hereinafter usually abbreviated as "wt%") of ammonium dichromate + 49 wt% of 28 wt% aqueous solution of ammonia + 49 wt%
pure water stripping conditions: ambient temperature, 15 minutes, immersion.
CA 02207179 1997-06-0~
The appearance of the coatings was inspected visually, and the mor-phology and size of the grains in the conversion coating was evaluated by inspection with a scanning electron microscope (SEM).
Example 1 5 Composition of the conversion bath phosphate ions : 15 g/L (from addition of 75% phosphoric acid) zinc ions : 1.3 g/L (from addition of zinc oxide) nickel ions : 1.0 g/L (from addition of nickel carbonate) manganese ions : 0.5 g/L (from addition of manganese carbonate) fluoride ions : 100 ppm (from addition of 55 % hydrofluoric acid) 450 ppm of tert-butyl hydroperoxide (organoperoxide component) was added to the conversion bath with the above composition, and the free acidity of the conversion bath was then adjusted to 0.9 point. A cold-rolled steel test sheetpon was subjected first to the colloidal titanium surface-conditioning treatment and then to conversion treatment (conversion temperature = 43 ~C, treatment time = 120 seconds) using the above-described conversion bath.
The resulting conversion coating weight was 1.2 g/m2. The coating crystals were plates with an average grain size of 6 micrometers. The conversion coating was grayish black and was uniform, fine, and dense.
Example 2 A galvanized steel test sheet was subjected first to the same surface conditioning ll~l",el)t as in E)~dulple 1 and then to conversion treatment usingthe same conversion treatment bath as in Example 1. The resulting conversion coating weight was 2.8 g/mZ. The crystals were plates with an 2s average grain size of 4 micrometers. The conversion coating was grayish white and was uniform, fine, and dense.
ExamPle 3 A cold-rolled steel test sheet was subjected first to the same sur-face-condilioning treatment as in Example 1 and then to conversion treatment using the same conversion treatment bath as in Example 1, except that the or-ganoperoxide addition consisted of 80 ppm tert-butyl hydroperoxide and the free acidity was adjusted to 0.6 point. The resulting conversion coating weight CA 02207179 1997-06-0~
W 096/17976 PCT~US95/lS227 was 0.9 g/m2. The coating crystals were plates with an average grain size of 8 micrometers. The conversion coating was grayish black and was uniform, fine, and dense.
ExamPle 4 A cold-rolled steel test sheet was subjected first to the same surface conditioning l,e~l",ent as in Example 1 and then to conversion treatment using the same conversion treatment bath as in Example 1, except that 1,200 ppm of tert-butyl hydroperoxide was added as the organoperoxide and sufficient 65.5% nitric acid was added to give a nitrogen component content of 500 ppm.
The free acidity of the conversion bath was adjusted to 0.9 point. The resulting conversion coating weight was 1.1 g/m2. The coating crystals were plates with an average grain size of 7 micrometers. The conversion coating was grayish black and was uniform, fine, and dense.
ExamPle 5 ~6 A ~ld-rolled s~.eel t~:st sheei ~rs suojected to conversion treatment as in Example 1, except that there was no surface-conditioning treatment and only 400 ppm of tert-hexyl hydroperoxide was added as the organoperoxide.
The free acidity was adjusted to 0.9 point. The resulting conversion coating weight was 1.0 g/m2. The coating crystals were plates with an average grain size of 6 micrometers. The conversion coating was grayish black and was uniform, fine, and dense.
ExamPle 6 A cold-rolled steel test sheet was subjected first to the same surface condilioning treatment as in Example 1 and then to conversion treatment using z5 the same conversion treatment bath as in Example 1, except that 100 ppm of peracetic acid was added as the organoperoxide, and the free acidit~ was ad-justed to 0.6 point. The resulting conversion coali"g weight was 1.3 glm2. The coating crystals were plates with an average grain size of 10 micrometers.
The conversion coating was grayish black and was uniform, fine, and dense.
Example 7 A cold-rolled steel test sheet was subjected to conversion treatment us-ing the same conversion bath as in Example 1, except that the surface condi-CA 02207179 1997-06-0~
W O 96/17976 PCTrUS95/15227 tioning treatment was not used, 500 ppm of tert-butyl hydroperoxide was added as the organoperoxide, and the free acidity was adjusted to 0.6 point.
The resulting conversion coating weight was 1.1 g/m2. The coating crystals were plates with an average grain size of 10 micrometers. The conversion~ coating was grayish black and was uniform, fine, and dense.
ExamPle 8 Composition of the conversion bath phosphate ions : 15 g/L (from addition of 75 % phosphoric acid) zinc ions : 1.3 g/L (from addition of zinc oxide) ~0 nickel ions : 1.0 g/L (from addition of nickel nitrate) manganese ions : 0.5 g/L (from addition of manganese carbonate) fluoride ions : 100 ppm (from addition of 55 % hydrofluoric acid) nitrate ions : 7.2 g/L (from addition of sodium nitrate and nickel ni-trate) (nitrogen concentration = 1.4 g/L).
450 ppm of tert-butyl hydroperoxide (organoperoxide component) was added to the conversion bath with the above composition, and the free acidity of the conversion bath was then adjusted to 0.9 point. A cold-rolled steel test sheetpon was subjected first to the colloidal titanium surface-conditioning treatment and then to conversion treatment (conversion temperature = 43~C, treatment time = 120 seconds) using the above-described conversion bath.
The resulting conversion coating weight was 1.1 g/m2. The coating crystals were plates with an average grain size of 5 micrometers. The conversion coating was grayish black and was uniform, fine, and dense.
Comparative Example 1 A cold-rolled steel test sheet was subjected to the same surface condi-tioning treatment as in Example 1 and was then submitted to the same conver-sion treatment as in Example 1, except that the organoperoxide addition con-sisted of 5 ppm of tert-butyl hydroperoxide. The conversion coating weight was 0.5 g/m2, and the development of yellow rust was observed.
Comparative ExamPle 2 A galvanized steel test sheet was subjected to conversion treatment as in Example 1, except that the organoperoxide addition consisted of 5 ppm of CA 02207l79 l997-06-0~
Wo 96/17976 PCT/US95/15227 tert-butyl hydroperoxide. The conversion coating weight was 0.9 g/m2 the average grain size was 15 micrometers and the coating was sparse.
Com~arative Example 3 A cold-rolled steel test sheet was subjected to conversion treatment as in i-=~(dlllplC 8 except that there was no surface-col1diliol ~ing treatment and 150 ppm of nitrite salt was added to the conversion bath in place of the organoper-oxide. The conversion coating weight was 0.1 g/m2 whici1 indicated that almost no conversion coating deposition had occurred. Yellow rust had developed over the entire surface.
.0 ComParative Example 4 A cold-rolled steel test sheet was subjected to conversion treatment as in Example 1 except that sodium chlorate was added to the conversion bath in place of the organoperoxide. The sodium chlorate was added to give a chlorate ions conce~ liol) of 1.5 g/L. The conversion coating weight was 0.9 9/m2. The codlil,~ crystals were columnar and the average grain size was 15 ~,i run,eters. The conversion codlill~ was sparsely deposited and yellow rust was observed.
The co"dilio"s and results of these examples are summarized in Table 1 below.
The organoperoxide conce"lrdlions used in Examples 1 to 8 were 50 to 1 500 ppm. It was thereby cler"onsl, dlad that this concentration range produceda good~uality conversion coating on cold-rolled steel sheet as well as galvan-ized steel sheet. A uniform dense and fine coali"g was obldi"ed even when the surface conditioning treatment was not used.
In co, lllasl Co",pdlalive Examples 1 and 2 used ûrgdl ,oper~xide concen-lrdlio"s beiow 50 ppm and it was found that in these cases the oxidation activity by the conversion accelerator was in~de~u~te~ resulting in the ~leposilion of scat-tered coating crystals. The uniformity of the coating on the basis metal was therefore diminished.
Co",pa,ali"e i~a,r,ples 3 and 4 used non-o,gci~operoxide conversion ac-cclerdlor~. In Colllpdldlive i-xample 3 a nitrite salt was used as the conversion accelerator and no surface~, ,.liliûr,i,)g 1, edll "ent was carried out. It was found W O96/17976 PCT~US95/15227 Examples Substrate Phos- Zinc Nitrogen Surface Oxidizing And phate Ions,Concen- Condi- Agent Colllpal~ re Ions, g/Ltration, tioning *
Examples g/L ppm Example 1 SPC 15 1.3 0 yes a F.x~mple 2 plated 15 1.3 0 yes a Example 3 SPC 15 1.3 0 yes a Example 4 SPC 15 1.3 500 yes a Example 5 SPC 15 1.3 0 no b Example 6 SPC 15 1.3 0 yes c Example 7 SPC 15 1.3 0 no a Example 8 SPC 15 1.3 1400 yes a Co~ Li~re Example 1 SPC 15 1.3 0 yes a Collll~al ~Li~e Example 2 plated 15 1.3 0 yes a Colllpal~ e Fx~mrle 3 SPC 15 1.3 1400 no d Comparative Fx~mrle 4 SPC 15 1.3 0 yes e grayish Fx~mrle 1 450 0 9 1.2 black plates 6 grayish Fx~mple 2 450 0.9 2.8 white plates 4 grayish F.x~mrle 3 80 0.6 0 9 black plates 8 grayish Example 4 1200 0.9 1.1 black plates 7 *Type of oxi~i~in~ agents added:
a tert-butyl hydroperoxide b tert-hexyl hydlopero~ide c peracetic acid d nitriteions e chlorate ions ... Table I is conVnued on V7e nex~ page ...
wo 96/17976 PCT/Us95/15227 Examples Substrate Phos- ZincMtrogen Surface Oxidizing And phate Ions,Concen- Condi- Agent Co~ al~;ve Ions, g/Ltration, tioning *
F~mrle~ g/L ppm grayish F.Y~mrle 5 400 0-9 1.0 black plates 6 grayish Example 6 100 0.6 1.3 black plates 10 grayish Example 7 500 0.6 1.1 black plates 10 grayish Example 8 450 0.9 1.1 black plates 5 yellow Col~lp~Live lUSt Example 1 5 0.9 0.5appeared columnar 13 Co-l.p~ ive sparse Example 2 ~ 0.9 0.9 coating columnar 15 yellow C~o.. pal ~ive rust Example 3 150 0.9 0.1appeared granular 80 C~ Li~e sparse Example 4 1500 0.9 0.9 coating col-lmnQr 15 that in this case conversion coating deposition was entirely absent.
A chlorate salt was used by itself as the conversion accelerator in Com-parative Example 4. It was found that in this case the conversion reaction rate was sul~sLdrllially slowed.
Benefits of the Invention The zinc phosphate-based conversion bath according to the present in-vention for application to metal substrates contains a,~,pro,u, iate concentrations of o~ uanoperuxide as conversion accelerator. In consequence thereof, this bath yields uniform, fine, and dense conversion coatings with coating weights ~o a~ uru~ul iale for the intended applications. This bath at the same time also acts to induce fine crystal formation in the conversion coating. As a result, the bath has such good effects that a surface-conditioning treatment is no longer a CA 02207179 1997-06-0~
W O 96117976 PCT~US95/15227 necessity.
The organoperoxides used by the present invention react under mild con-ditions and are more stable than the generally used inorganic accelerators, and as a consequence have very good economic attributes. Since the presence of s nitrogenous compounds in the conversion treatment bath is also no longer a ne-cessity, environmental regulations relating to the levels of ni~, oge~ ,ous compound discharge can now be fully satisfied, and on this point the conversion bath ac-cording to the present invention represents a major practical development.
Claims (8)
1. An aqueous acidic phosphate conversion coating treatment composition for metal surfaces said composition comprising water zinc ions phosphate ions and an accelerating component consisting essentially of one or more organoperoxides.
2. A composition according to claim 1 comprising from 50 to 1,500 ppm of the organoperoxide accelerating component.
3. A composition according to claim 2 having a pH value from 2.0 to 4Ø
4. A composition according to claim 3 having a pH value from about 2.5 to about 3.5.
5. A composition according to claim 1 having a pH value from 2.0 to 4Ø
6. A composition according to claim 5 having a pH value from about 2.5 to about 3.5.
7. A process for forming a phosphate conversion coating on a metal surface, wherein the metal surface is contacted with an aqueous liquid composition according to any one of claims 1 through 6.
8. A process according to claim 7 wherein the metal surface before the formation of a phosphate conversion coating thereon is degreased and then rinsed with water.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6/302289 | 1994-12-06 | ||
| JP30228994 | 1994-12-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2207179A1 true CA2207179A1 (en) | 1996-06-13 |
Family
ID=17907208
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002207179A Abandoned CA2207179A1 (en) | 1994-12-06 | 1995-12-06 | Zinc phosphate conversion coating composition and process |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0793737B1 (en) |
| AT (1) | ATE226648T1 (en) |
| CA (1) | CA2207179A1 (en) |
| DE (1) | DE69528664T2 (en) |
| ES (1) | ES2183891T3 (en) |
| WO (1) | WO1996017976A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5888315A (en) * | 1995-03-07 | 1999-03-30 | Henkel Corporation | Composition and process for forming an underpaint coating on metals |
| AU699822B2 (en) * | 1995-03-07 | 1998-12-17 | Henkel Corporation | Composition and process for forming an underpaint coating on metals |
| DE102011089714A1 (en) * | 2011-12-23 | 2013-06-27 | Chemetall Gmbh | Combating microorganisms in plants, aqueous rinse baths and/or aqueous compositions of a surface treatment, comprises protecting the aqueous bath, a rinse fluid and the aqueous composition for pretreatment before coating |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2471908A (en) * | 1948-04-08 | 1949-05-31 | American Chem Paint Co | Method of and material for preparing surfaces of ferriferous metals for the reception of a siccative finishing coat |
| US3161549A (en) * | 1955-04-08 | 1964-12-15 | Lubrizol Corp | Solution for forming zinc phosphate coatings on metallic surfaces |
| FR1192515A (en) * | 1957-12-31 | 1959-10-27 | Process for preparing iron or steel parts for cold forming | |
| DE1095625B (en) * | 1959-02-27 | 1960-12-22 | Collardin Gmbh Gerhard | Process for phosphating metals |
| GB1272772A (en) * | 1968-08-16 | 1972-05-03 | Ici Ltd | Phosphating solutions |
| US3642541A (en) * | 1969-02-12 | 1972-02-15 | Republic Steel Corp | Method for applying corrosion-resistant composite coating to ferrous metals and product resulting therefrom |
| NZ188918A (en) * | 1977-11-29 | 1981-01-23 | Ici Ltd | Applying phosphate coating to ferrous or zinciferous metal substrate and materials therefor |
| US4171231A (en) * | 1978-04-27 | 1979-10-16 | R. O. Hull & Company, Inc. | Coating solutions of trivalent chromium for coating zinc surfaces |
| DE3913089A1 (en) * | 1989-04-21 | 1990-10-25 | Henkel Kgaa | CHLORATE- AND NITRITE-FREE METHOD FOR THE PRODUCTION OF NICKEL- AND MANGANE-CONTAINING ZINC PHOSPHATE LAYERS |
-
1995
- 1995-12-06 EP EP95942466A patent/EP0793737B1/en not_active Expired - Lifetime
- 1995-12-06 AT AT95942466T patent/ATE226648T1/en not_active IP Right Cessation
- 1995-12-06 DE DE69528664T patent/DE69528664T2/en not_active Expired - Fee Related
- 1995-12-06 ES ES95942466T patent/ES2183891T3/en not_active Expired - Lifetime
- 1995-12-06 CA CA002207179A patent/CA2207179A1/en not_active Abandoned
- 1995-12-06 WO PCT/US1995/015227 patent/WO1996017976A1/en active IP Right Grant
Also Published As
| Publication number | Publication date |
|---|---|
| WO1996017976A1 (en) | 1996-06-13 |
| ATE226648T1 (en) | 2002-11-15 |
| EP0793737A1 (en) | 1997-09-10 |
| EP0793737A4 (en) | 1998-03-04 |
| DE69528664D1 (en) | 2002-11-28 |
| ES2183891T3 (en) | 2003-04-01 |
| MX9702738A (en) | 1997-09-30 |
| EP0793737B1 (en) | 2002-10-23 |
| DE69528664T2 (en) | 2003-07-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0106459B1 (en) | Phosphate coating metal surfaces | |
| KR100250366B1 (en) | Acid aqueous compositions and concentration in order to make zinc phosphate coating on the meal plate | |
| US20110180186A1 (en) | Method and solution for coating metallic surfaces with a phosphating solution containing hydrogen peroxide, metallic object produced and use of the object | |
| MXPA97003675A (en) | Compositions of zinc phosphate pararecubriment containing ox accelerators | |
| GB2106146A (en) | Aqueous acidic zinc-phosphate solutions for low temperature coating iron and/or zinc | |
| US4003761A (en) | Process for the production of sprayed phosphate coats on iron and steel | |
| AU740987B2 (en) | Aqueous solution and method for phosphatizing metallic surfaces | |
| US6231688B1 (en) | Composition and process for zinc phosphate conversion coating | |
| US6485580B1 (en) | Composition and process for treating surfaces or light metals and their alloys | |
| US5932292A (en) | Zinc phosphate conversion coating composition and process | |
| AU712410B2 (en) | Moderate temperature manganese phosphate conversion coating composition and process | |
| KR19990082154A (en) | Zinc phosphate treatment method using low concentration of copper and manganese | |
| CA2207179A1 (en) | Zinc phosphate conversion coating composition and process | |
| US5232523A (en) | Phosphate coatings for metal surfaces | |
| US5888315A (en) | Composition and process for forming an underpaint coating on metals | |
| SK112498A3 (en) | Zinc-phosphatizing method using low nickel and/or cobalt concentrations | |
| EP0055615B1 (en) | A method for forming a conversion coating on a metal surface | |
| AU699822B2 (en) | Composition and process for forming an underpaint coating on metals | |
| US6168674B1 (en) | Process of phosphatizing metal surfaces | |
| MXPA97002738A (en) | Composition and coating process deconversion of z phosphate | |
| CA2244902C (en) | Moderate temperature manganese phosphate conversion coating composition and process | |
| EP1290244A1 (en) | Method for forming phosphate coatings on nonferrous metals and plated steel sheets | |
| WO1997020964A1 (en) | Composition and process for zinc phosphate conversion coating | |
| EP1177329A1 (en) | Composition and process for treating surfaces of light metals and their alloys | |
| CA2237889A1 (en) | Composition and process for zinc phosphate conversion coating |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |