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
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D19/00—Degasification of liquids
  • B01D19/02—Foam dispersion or prevention
  • B01D19/04—Foam dispersion or prevention by addition of chemical substances
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D19/00—Degasification of liquids
  • B01D19/02—Foam dispersion or prevention
  • B01D19/04—Foam dispersion or prevention by addition of chemical substances
  • B01D19/0404—Foam dispersion or prevention by addition of chemical substances characterised by the nature of the chemical substance

Definitions

• the present invention provides an acid pickling solution containing a wetting agent, the solution also containing an anti'foa'ming agent consisting essentially of a mixture of octadecaediol-l,12 and a paraffin oil.
• the present invention relates to a process for preventing the formation of foam in acid pickling solutions which contain wetting agents and which are used mainly for the simultaneous pickling and cleaning of metal surfaces.
• wetting agents are added to the conventional pickling acids such as hydrochloric acid, sulfuric acid and phosphoric acid. Mixtures of wetting agents are also generally used, preferably non-ionic wet ting agents because of their higher solubility and better degreasing effect.
• non-ionic wetting agents are the products of addition of ethylene oxide to alkylphenols, optionally mixed with alkylbenzenesulfonates if required.
• the non-ionic wetting agents are known to foam only to a slight extent in the alkaline pH range, but they undergo considerable foam formation when used in an acid environment.
• anionic active wetting agents which foam to a considerable extent in the alkaline pH range because of their good solubility in that range, undergo only a slight foam development in the acid pH range.
• these anionic active wetting agents can only be used to a limited extent and are furthermore less effective with respect to degreasing.
• antifoaming agents In order to prevent an excess formation of foam, antifoaming agents have to be added to the acid pickling solutions containing Wetting agents. This is particularly necessary when pickling is carried out at low temperatures, for example, when using hydrochloric acid as a pickling agent. Moreover an anti-foaming agent frequently has to be added to sulfuric acid pickling solutions containing Wetting agents and to phosphoric acid pickling solutions containing wetting agents which are frequently used at higher temperatures. The anti-foaming agents are added in order to prevent any considerable formation of foam when discharging these wetting agents containing solutions into a waste water treatment plant.
• the conventional anti-foaming agents for the neutral and alkaline pH ranges have proved to be ineffective in acid pickling solutions or have resulted in significant operating difiiculties during surface treatment processes such as galvanic treatment, which frequently follows pickling and degreasing. These troublesome influences can cause, for example, poor adhesion of the galvanic layer to the base metal.
• the present invention is directed to an acid pickling solution comprising a pickling acid, a wetting agent, and an anti-foaming agent consisting essentially of a mixture of octadecanediol-l,l2 and a parafiin oil.
• the present invention is also directed to a process for pickling metals wherein the improvement comprises contacting the metal with an acid pickling solution comprising a pickling acid, a wetting agent, and an anti-foaming agent consisting essentially of a mixture of octadecanediol-1,l2 and a parafiin oil for a time sufficient to effect pickling and degreasing.
• an acid pickling solution comprising a pickling acid, a wetting agent, and an anti-foaming agent consisting essentially of a mixture of octadecanediol-1,l2 and a parafiin oil for a time sufficient to effect pickling and degreasing.
• the foam-inhibiting effect is obtained only by a mixture of the two substances, i.e. the formation of foam is not prevented solely by octadecanediol-1,12 or solely by paraffin oil. Similarly, other diols mixed with paraffin oil are virtually ineffective. Octadecanediol-l,12 and parafiin oil are generally present in the pickling solutions in the Weight ratio of 4:1 to 1:3.
• the mixture of octadecanediol-LIZ and paraflin oil is added to the pickling solutions in a concentration of from 0.5% to 10.0% by weight based on the content of Wetting agent. It is to be recognized that the preferred concentration is dependent upon the wetting agent or mixture of wetting agents used, and upon the particular pickling acid.
• the diol/oil mixture of the present invention is added to the pickling solutions in a concentration of 0.05% to 2.0% by weight based on the acid concentration.
• concentration 0.05% to 2.0% by weight based on the acid concentration.
• the most preferred concentration is again dependent upon the particular wetting agent or upon the mixture of wetting agents used, and upon the particular pickling acid.
• the process has proved to be particularly advantageous if the mixture of octadecanedioll,l2 and paraffin oil is added to the pickling solutions in a concentration of from 0.1% to 1.2% by weight relative to the acid content, and from 1% to 7% by weight relative to the content of wetting agent.
• the parafiin oil is a refined mixture of hydrocarbons having a viscosity of to 200 cst. at 20 C.
• the pickling solutions may additionally contain chlorohydrocarbons, preferably trichloroethylene.
• the preferred pickling compositions of the invention comprise from about 5% to 25% ofa pickling acid selected from the group consisting of hydrochloric acid, sulfuric acid and phosphoric acid, from about 0.2% to 5% of a wetting agent selected from the group consisting of non-ionic surface active compounds, and mixtures of non-ionic surface active compounds and anionic surface active compounds, and a content of an anti-foaming agent consisting of a mixture of octadecanediol-l,12 and paraffin oil having a viscosity of between 100 and 200 cst.
• a pickling acid selected from the group consisting of hydrochloric acid, sulfuric acid and phosphoric acid
• a wetting agent selected from the group consisting of non-ionic surface active compounds, and mixtures of non-ionic surface active compounds and anionic surface active compounds
• an anti-foaming agent consisting of a mixture of octadecanediol-l,12 and paraffin oil having a vis
• the weight ratio of said octadecanediol- 1,12 to said paraflin oil being between 4:1 to 1:3, said anti-foaming agent being present in an amount of from 0.5% to 10% by weight based on the amount of wetting agent and from 0.05% to 2% by weight based on the amount of pickling acid.
• the non-ionic surface active compounds employed are alkylphenols having 6 to 12 carbon atoms in the alkyl, condensed with from 4 to 20 mols of ethylene oxide.
• the anionic surface active compounds employed are alkylbenzene-sulfonic acids having from 8 to 24 carbon atoms in the alkyl.
• the pickling and degreasing process is conducted in the usual manner by contacting the surface of the metal, such as iron, steel, aluminum, etc. with a pickling composition of the invention at temperatures of from 15 C. to 80" C. for a period of about 1 second to about 5 minutes. Thereafter the metal surfaces are rinsed and dried.
• the metal such as iron, steel, aluminum, etc.
• Example 1 0.01% octadecanediol-1,12 and 0.01% paraflin oil (150 cst.) were added to a 15% hydrochloric acid solution which contained 0.7% nonylphenol-l-IS E.O. (where 15 ED. means the product of addition of 15 moles of ethylene oxide to 1 mole of nonylphenol).
• the development of foam was determined at room temperature in accordance with DIN 53902, both with and without the addition of anti-foaming agent. The volume of foam was read off immediately after the foam had been produced at time equal to zero minutes and after 1 minute. 'In the absence of an anti-foaming agent, the volume of foam amounted to 600 ml. after minutes and 500 ml. after 1 minute; while the volume of foam amounted to 300 ml. after 0 minutes and 0 ml. after 1 minute with the above addition of octadecanediol-1,12 and paraflin oil.
• Example 2 The following Tables 1 and 2 show the volumes of foam, according to DIN 53902, which were obtained when using a 15% hydrochloric acid solution having a content of 2.85% nonylphenol+9.5 ED. and 0.15% dodecylbenzene sulfonic acid at room temperature without an additive and with the addition of the given additive substances. The volume of foam was measured immediately after the foam had been produced at time equal to zero minutes and after minutes.
• Table 1 shows the results obtained with octadecanediol-1,12, parafiin oil, and mixtures of these two substances.
• Example 4 1.4% nonylphenol+11 ED. and 0.06% alkylbenzene sulfonic acid were added to a 10% phosphoric acid solution to produce solution 1; and the volume of foam was ascertained, in accordance with DIN 53902 at room temperature. For comparison the volume of foam in a 10% phosphoric acid solution was determined after 0.035% octadecanediol-1,l2 and 0.035% parafiin oil cst.) had been added to the phosphoric acid solution in addition to the above-mentioned wetting agents to produce solution 2. In the case of solution 1, the volume of foam amounted to:
• Aluminum parts contaminated with residues of polishing paste were degreased and pickled at 60 to 80 C. in a solution containing 5% phosphoric acid, 2% nonylphenol 9.5 E.O., 0.06% octadecanediol-l,l2 and 0.04% paraflin oil (120 cst.).
• An aqueous pickling bath consisting essentially of from about 5% to 25% of a pickling acid selected from the group consisting of hydrochloric acid, sulfuric acid and phosphoric acid, from about 0.2% to 5% of a wetting agent selected from the group consisting of (a) an addition product of 4 to 20 moles ethylene oxide to 1 mole of alkylphenol having 6 to 12 carbon atoms in the alkyl,
• said wetting agent consists of from to by weight based upon the weight of said wetting agent of said addition product of (a) and from 0% to 5% by weight of said alkylbenzenesulfonate of (b) based upon the weight of said wetting agent.
• a pickling acid selected from the group consisting of hydrochloric acid, sulfuric acid and
• the weight ratio of said octadecanediol-1,12 to said paraflin oil being between 4:1 to 1:3, said anti-foaming agent being present in an amount of from 0.5% to 10% by weight based on the amount of wetting agent and from 0.05% to 2% by weight based on the amount of pickling acid.

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Cited By (2)

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• 1971
  • 1971-02-02 DE DE2104699A patent/DE2104699C3/de not_active Expired
  • 1971-12-31 SE SE7116971A patent/SE376848B/xx unknown
• 1972
  • 1972-01-26 US US00221039A patent/US3776852A/en not_active Expired - Lifetime
  • 1972-01-28 IT IT19935/72A patent/IT948047B/it active
  • 1972-02-01 GB GB459372A patent/GB1318676A/en not_active Expired
  • 1972-02-01 ES ES399380A patent/ES399380A1/es not_active Expired
  • 1972-02-01 ZA ZA720648A patent/ZA72648B/xx unknown
  • 1972-02-01 BR BR548/72*[A patent/BR7200548D0/pt unknown
  • 1972-02-02 JP JP1212572A patent/JPS5432420B1/ja active Pending
  • 1972-02-02 FR FR7203429A patent/FR2124373B1/fr not_active Expired

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