JPH05247664A - Concentrate for activating and refining bath and bath obtained from the concentrate - Google Patents

Abstract

Concentrate for an activating and refining bath used in phosphating processes employing zinc, characterised in that it is based on an aqueous dispersion which has a content of 2 to 20 % by weight of Jernstedt salt, the titanium content of the dispersion being consequently from 140 to 10,000 ppm of Ti, this dispersion additionally comprising: - a proportion of 0.2 to 8 % by weight of at least one dispersing or sequestering agent and - a proportion of 0.05 to 7 % by weight of at least one polysaccharide-based thickening agent.

Description

Detailed Description of the Invention

[0001]

The object of the present invention is to provide a liquid for providing an active and refining bath containing titanium for use during the process of crystalline zinc phosphating by diluting with a reasonable amount of water. I have a concentrate.

The invention further relates to the active and refining baths obtained from the above concentrates. Steel, aluminum,
Processes for the treatment of crystalline zinc phosphating on galvanized steel, or galvanized steel or iron alloys alloyed with nickel, cobalt, aluminium, are intended to protect said substrates from corrosion or to make these substrates cold. It is often used to reduce the coefficient of friction when subjected to processing.

These processes generally consist of 6 stages: -one or more stages of alkaline degreasing-one or more stages of rinsing with running tap water-one stage of activation and scouring Correctly speaking, one step of phosphoric acid treatment of zinc, one or more steps of rinsing with water, preferably final passivation, especially with a hexavalent chromium salt or a salt of a mixture of hexavalent chromium and trivalent chromium. One stage of rinsing of treatment.

To put it frankly, it is possible to produce chemical inhomogeneities on the metal surface whose active stage has been cleaned, before the phosphoric acid treatment. As a result, the generation of a crystalline phosphate layer is promoted and a thin and dense coating can be obtained. Such coatings are: -to improve the adhesion of paint layers that may be used later, and to improve the corrosion resistance in case of damage to the paint layer or coating-or in the cold working environment In order to deposit crystals that adhere firmly to the metal substrate.

In particular, the activation and phosphoric acid treatment steps are generally carried out by spraying a suitable bath on the substrate, or by dipping the substrate in the bath, or by continuous spraying and dipping.

[0006] The step of activity may be at the same time as the step of degreasing by mixing the concentrated active product with an aqueous degreasing solution, or by making a degreasing active bath from a concentrated degreasing composition containing the active concentrate. May be performed at the same time as the degreasing step. Two such simultaneous treatments are carried out in a surface treatment facility in which only spraying is carried out in the phosphoric acid treatment stage. However, if the phosphating step also comprises a soaking phase, fine and dense phosphating can only be achieved by means of an active, independent step method.

The titanium used in the activation and refining stages constitutes the refining agent. The active and scouring baths are generally based on titanium salts and contain alkali metal phosphates.

Alkali metal phosphates and eg US patents
It is known to make these from solid, powdery concentrates consisting of a mixture of colloidal titanium salts known under the name Jernstedt salt described in 2,456,947.

Such a Gernsted salt can be obtained by mixing 95 parts of disodium hydrogen phosphate and 5 parts of potassium fluorotitanate in sufficient water to dissolve them. Sodium and potassium polyphosphates may also be added to this mixture, in particular in the proportion ^1-300 by weight of P ₂ O ₇ ^4- . Moisture is then removed from the mixture by evaporation until a powdery product is obtained.

Titanium sulfate, oxide or oxysulfate may be used in place of potassium fluorotitanate as the titanium raw material.

One example of a Gernsted salt that is commonly used and is marketed by the applicant under the trademark FIXODINE 5 has the following components: as titanium (IV) in the form of titanium phosphate. Represented titanium 0.7-5% by weight sodium phosphate 85-99.3% by weight sodium polyphosphate 0-10% by weight.

As indicated above, the known concentrates used for making active and refining baths are powdery products.

However, these have the following drawbacks.・ To remove water in the manufacturing process, 110
Unless it is considered uneconomical to heat to temperatures above ° C, powdered products contain water, so that some of the water remains in the product powder. This leads to the formation of lumps, which makes dissolution difficult. The formation of these lumps is also promoted by the humidity in the workplace where the surface treatment is performed and also by the water absorption of the powder. • These concentrates contain a non-negligible proportion of fine particles that may contaminate the environment where they are used. In addition, the production of active baths requires the user to produce the mother liquor from the concentrate. This mother liquor must be prepared with vigorous stirring, as the Gernsted salt is extremely difficult to dissolve under such manufacturing conditions. • During the production of the active bath, these products must be placed in the dilution water gently, and therefore preferably automatically, because the activation step induces the nucleation of the phase after the phosphoric acid treatment. .. However, automatic introduction is often designed with an endless screw under the feed hopper for the powder, which compresses the powder and often forms lumps that interfere with the operation of the screw. Is causing

Up until now, it has been necessary to commercialize in powder form. It is possible that once the Gernsted salt is mixed in water it forms a suspension of insoluble crystals after a few hours, these crystals increasing in size over time, only fine crystals (< 3 μm) due to the fact that it is known to have the desired active effect. Proposed to use liquid concentrates based on Gernstedt salt, and to use liquid concentrates which do not have the disadvantages due to the properties of the powders of the above solid concentrates because they become liquid (EP-A-454,21
2).

However, despite the fact that these liquid concentrates are stored for several months without the formation of precipitates by the addition of thickeners, especially the known polysaccharides due to their multiple thickening properties, they are sufficiently high. It has the major drawback that it must contain a titanium concentration, so that when diluted with normal amounts of water it provides an effective active bath after storage for several months, ie finely crystalline. It must have a titanium content capable of imparting the required active properties to the bath, even in the liquefied state. The high content of such titanium in the concentrate makes the active bath produced from this concentrate, on the contrary, immediately after the production of the latter, or shortly thereafter, and therefore before crystal growth takes place. The result is that the treatment of the substrate has a high titanium concentration, which occurs on highly activated surfaces, resulting in virtually zero layer thickness during the full-scale phosphoric acid treatment step. Will result. This layer is therefore a passive layer rather than a phosphoric acid treated layer.

[0016]

SUMMARY OF THE INVENTION It is therefore the main object of the present invention to provide a concentrate which is suitable for the production of this type of active and refining baths, which does not have the disadvantages of the prior art concentrates. It is a purpose. 2 to 2 of the above concentrate
If in the form of an aqueous dispersion containing 0% by weight of the Gernsted salt, the concentration of titanium in the dispersion is therefore 140 to 10,000 ppm of titanium, and this dispersion is: At least one dispersant or sequestrant in a proportion of 0.2 to 8% by weight and-at least one thickener based on a polysaccharide as defined below 0.05 to 7% by weight Then, it is a merit of the applicant company that it has been discovered that this purpose is achieved.

The concentrate thus constituted is physically stable for at least 3 months and in its activity, at any time, ie immediately after its production or even after storage for several months, likewise, It provides an active bath, a scouring bath, which has a titanium content of 1 to 75 ppm by dilution with a colleague's water and gives satisfactory results with regard to the activity of the treated substrate.

[0018]

The present invention therefore contains from 2 to 20% by weight of the Gernstedt salt, depending on the active concentrate used for the purpose of the zinc phosphating process, a concentrate which is suitable for the production of scouring baths for that purpose. Having an aqueous dispersion of Gernstedt salt. This dispersion is 140
Corresponding to a titanium concentration of from 10,000 to 10,000 ppm, the above dispersion further contains the following substances: Alkali metal phosphonates or ammonium phosphonates, or alkali carboxylic acids with sequestering agent activity. 0.2 to 8 of at least one dispersant or sequestering agent selected from the group consisting of metal salts or ammonium salts, and all combinations of several of these derivatives.
Percentage by weight, which is understood as follows: the phosphonate is preferably selected from the group consisting of the following phosphonates: hydroxymethylphosphonic acid hydroxypropylphosphonic acid 1-hydroxyethylidene-1 , 1-diphosphonic acid, amino-tri (methylene-phosphonic) acid, ethylene-diamino-tetra (methylene-phosphonic) acid, 2-phosphono-butane-1,2,4-tricarboxylic acid, Of some carboxylic acids, nitrile triacetic or NTA are preferred, especially carbohydrates composed of sugars such as glucose, sucrose, fructose, maltose, lactose, galactose and / or
Or in particular organic and / or alkali metal nitrates
Alternatively, a nutrient medium based on an inorganic nitrogen source, an inorganic ammonium salt, sodium caseinate, or a soluble extract of cereals was added to Xanthomonas or Sclerothia.
erotia), Xanthomonas campestris (Xanthomon)
as campestris) or Sclerotium lolfushii (S
clerotium rolfsii) at least one thickener 0.05 based on a polysaccharide obtained by fermentation by the action of
To 7% by weight is preferred.

The proportion of Gernstedt salt is preferably 4 to 15% by weight of the liquid concentrate.

The proportion of sequestrant or dispersant is preferably from 4 to 15% by weight of the liquid concentrate.

The proportion of polysaccharide is preferably 4 to 15% by weight of the liquid concentrate.

The liquid concentrates according to the invention may contain antifreeze compounds, so that they can also be stored below 0 ° C. The antifreeze compound may be selected from glycol derivatives such as ethylene glycol, propylene glycol or high molecular weight glycols or nitrogen derivatives such as urea.

The pH of the liquid concentrate is preferably 7 to 1
It is adjusted to 0, more preferably 7 to 9. Derivatives of alkali metals such as soda, potato, carbonates of alkali metals, carbonates of ammonium hydroxide, phosphates such as trisodium phosphate, tripotassium phosphate, sodium and potassium pyro- and tripolyphosphates, citrates. It is carried out by using an alkali metal salt or ammonium salt of a carboxylic acid such as an acid.

The active, scouring bath according to the invention obtained by diluting the above concentrate to an aqueous solution of 3-30 g / l contains: 60 to 6000 mg / l of Gernstedt salt, ie an alkali metal 1 to 75 mg / l of titanium in the form of titanium phosphate in the phosphate matrix of 15:15 to 1500 mg / l of a carboxylic acid derivative having a sequestering agent activity and / or a dispersible phosphonic acid derivative: 3 To 600 mg / l of the nutrient medium containing the polysaccharides obtained from the microbial fermentation, the volume being made up to 1 liter with water.

Immediately after production, or at any time,
And by constant dilution for at least 3 months after manufacture,
To demonstrate the suitability of the concentrate according to the invention for providing a completely satisfactory activity, refining bath during the zinc phosphating process,
A test consisting of measuring the efficiency of the bath obtained by diluting the concentrate according to the invention during the surface treatment step consisting of phosphoric acid treatment was carried out on the one hand immediately after dilution and on the other hand after storage at various temperatures.

The surface treatment process, which is the same for all tests for efficiency, consists of the following steps:・ The applicant company is RIDOLINE 1550CF /
The applicant company added RIDOSOL to a 2% aqueous solution of an alkali silicate degreasing agent sold under the trademark of 2.
Alkaline degreasing by immersion in an aqueous solution containing 0.2% of a surface-active compound added under the trademark 550CF for 3 minutes at 60 ° C.-rinsing with running tap water at room temperature-water and liquid concentrate according to the invention Activation by immersion in a dilute bath prepared from the product for 1 minute at room temperature • 3 minutes in an aqueous solution based on the acidic zinc phosphate marketed by the applicant company under the trademark GRANODINE 958CF. Phosphoric acid treatment with zinc at 53 ° C · Rinse with running tap water · Dry for 5 minutes in a stream of heated air at 80 ° C The purpose here is to vary the morphology and amount of zinc phosphate crystals deposited during the active phase. Since it is to study the effect of the active baths, the passivation and subsequent usual steps of paint application were omitted. The morphology may be examined by a scanning electron microscope adjusted to a magnification of 1500 times.

The stability may be examined by weighing the amount of zinc phosphate deposited after the deposit is dissolved in the refining medium.

The substrate used in the test is a sheet of cold rolled steel, electrogalvanized steel or hot galvanized steel, the size of which is 10 cm × 20 cm × 0.7 mm.

The invention will be better understood by the following examples which describe the advantageous embodiments of the invention, which are not intended to limit the invention in particular.

[0030]

【Example】

Example 1 100 g of Gernstedt salt (commercially available under the trademark Fixodyne 5 by the applicant company), 4 g of polysaccharides (commercially available under the trademark KELZAN S by KELCO) and 1 -Hydroxy-ethylidene-1,1-diphosphonic acid tetrasodium salt 1
0 g is diluted in 500 g of 60 ° C. deionized water with vigorous stirring.

This composition was prepared by adding deionized water to 100
Set to 0g.

The product is homogenized and used as a liquid concentrate according to the invention.

This product was deionized water at a rate of 10 per liter.
Dilute to g to prepare a dilute aqueous activation solution or activation bath.

The liquid concentrate is homogeneous and opalescent. Divide this into 3 equal parts, 4 ℃, 20 ℃, 40 ℃
Store at ℃ for 3 months.

After this storage, and after the fractions stored at 4 ° C. and 40 ° C. respectively were adjusted to 20 ° C., any of these parts showed any significant signs of phase separation, precipitation, crystallization or thickening. Inspect to make sure it is not awake.

The active bath obtained from this concentrate and the powdered Gernsted salt (Fixodyne 5 from the applicant company)
Marketed under the trademark)).

The above-mentioned surface treatment was performed and the following results were obtained.

[0038]

[Table 1]

[0039]

[Table 2] The liquid concentrate according to the invention is stable even after storage for 3 months, and the liquid concentrate according to the invention shows the activity of the bath obtained from the solid powder concentrate of the prior art at the end of March. Tables 1 and 2 show that baths having equivalent activity are provided. Example 2 A liquid concentrate was prepared for the active bath by the same method as described in Example 1, but normally used to stabilize an aqueous concentrate containing a dispersion of solids. The polysaccharide was replaced with a thickener that is used. The other ingredients are unchanged.

These samples were stored at 4 ° C., 20 ° C. and 40 ° C. respectively and the time at which more than 10% by volume of the concentrate separated was recorded. This phenomenon is considered unacceptable for the stability of liquid concentrates. The results are summarized in Table 3.

[0041]

[Table 3] * 1 Trademark SECAL GUM A500; CECA
Marketed by the company * 2 Trademark BRANOSE 7HC; HOEC
Commercially available from HST * 3 Trademark CLARSOL FB2; CECA
Marketed by the company * 4 Trademark BENTONE 38; CECA
Marketed by the company * 5 Trademark VEEGUM F; marketed by VAN DER BILT company Table 3 is based on cellulose such as carboxymethyl cellulose and has a Brookfield viscosity at a rotation speed of 20 rpm / min. It was shown that any thickener had a stability comparable to that obtained in Example 1, even when used at the concentrations normally used to produce viscosities of 800 cps to 2000 cps, as measured with a meter. ing. The thickener is the decisive factor. Example 3 A liquid concentrate was prepared for an active bath prepared in the same manner as described in Example 1, except that 1-hydroxyethylidene-1,1-diphosphonic acid was dispersed in various other dispersions. The agent was replaced. The other ingredients were unchanged.

Samples of these concentrates were stored at 4 ° C., 20 ° C., 40 ° C.
Stored at 0 ° C, the time required for the appearance of persistent crystallization was recorded when the temperature returned to 20 ° C. It is believed that the appearance of this phenomenon cannot be approved for liquid concentrates.

The concentrate is then deionized water at 10 g / l.
The active bath was made with it and the surface treatment described in Example 1 was performed on the steel sheet. The product was investigated to see if it was still active (crystals comparable to those obtained in Example 1). The results are summarized in Table 4.

[0044]

[Table 4] * 1 COATEX TH50-50 C
Commercially available from OATEX * 2 Tetrapotassium pyrophosphate * 3 Sodium tripolyphosphate * 4 Sodium hexametaphosphate NTA Nitrile Triacetic acid sodium salt ATP Amino-tri (methylenephosphonic) acid pentasodium salt Table 4 The examination of the results was done using an appropriate ratio of NT
Not only is the advantage that A and ATP only stabilize the concentrate according to the invention with respect to crystallinity, but also that after the concentrate has been stored at various temperatures, a bath in which the concentrate is still usable thanks to its active properties. It clearly shows that it has the advantage of guaranteeing that it can be provided.

Such a result is not trivial since the person skilled in the art is expecting all dispersants and / or sequestrants to work in a similar manner.

The need for the simultaneous presence in the liquid concentrate according to the invention of an effective amount of a sequestering agent and / or dispersant selected from each of the above groups and a polysaccharide was therefore clearly established. ..

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michel Südoul France 95270 Ryuzarshsan Martin du T TELTOUL ARE PABRO Picasso 5 (72) Inventor Verounik Le Rou Geneva Ahull France 92270 Boua Colomb Avenyu Le Minyoun 20

Claims (5)

[Claims] 1. A concentrate is based on an aqueous dispersion of this salt containing from 2 to 20% by weight of Jernstedt salt, the dispersion comprising titanium 140 to 10.0.
Corresponding to a concentration of 00 ppm, the dispersion is further: an alkali metal phosphonate or ammonium phosphonate, or an alkali metal salt or ammonium salt of a carboxylic acid having a sequestering agent activity, and all combinations of several of these derivatives. At least one dispersant or sequestering agent selected from the group consisting of 0.2 to 8
% By weight, which is understood as follows: the phosphonate is preferably selected from the group consisting of the following phosphonates: hydroxymethylphosphonic acid, hydroxypropylphosphonate, 1-hydroxyethylidene -1,1-diphosphonic acid, amino-tri (methylene-phosphonic) acid, ethylene-diamino-tetra (methylene-phosphonic) acid, 2-phosphono-butane-1,2,4-tricarboxylic acid, -Among the carboxylic acids having a sequestering activity, nitrile triacetic acid or NTA is preferable.-Carbohydrates composed of sugars such as glucose, sucrose, fructose, maltose, lactose and galactose, and / or
Or in particular organic and / or alkali metal nitrates
Alternatively, a nutrient medium based on an inorganic nitrogen source, an inorganic ammonium salt, sodium caseinate, or a soluble extract of cereals was added to Xanthomonas or Sclerothia (Scl).
erotia), Xanthomonas campestris (Xanthomon)
as campestris) or Sclerotium lolfushii (S
clerotium rolfsii) at least one thickener 0.05 based on a polysaccharide obtained by fermentation by the action of
Active, refining bath concentrates used in the zinc phosphating process characterized by the fact that a proportion of from 1 to 7% by weight is preferred. 2. A concentrate according to claim 1, characterized by the fact that the concentration of the Gernsted salt is preferably 4 to 15% by weight of the liquid concentrate. 3. A concentrate according to claim 1 or 2, characterized by the fact that the proportion of sequestrant or dispersant is preferably 0.5 to 5% by weight of the liquid concentrate. 4. A concentrate according to claim 1, characterized by the fact that the proportion of polysaccharide is preferably 0.1 to 2% by weight of the liquid concentrate. 5. An active, scouring bath is obtained by diluting the concentrate according to claim 1 to 4 to an aqueous solution of 3-30 g / l, the bath being: 60 to 6000 mg / l Gernstead. 1 to 75 mg / l of titanium in the form of titanium phosphate in a phosphate matrix of an alkali metal, i.e. an alkali metal phosphate matrix, 15 to 1500 mg / l of a carboxylic acid derivative having sequestering activity and / or dispersibility Containing 3 to 600 mg / l of a polysaccharide obtained from microbial fermentation of nutrient medium, characterized by the fact that its volume is made up to 1 liter of water, a scouring bath ..