DE2101631A1 - Removable, film-forming stain - Google Patents

Description

Dr.P / De Removable, film-forming stain

The invention relates to a peelable, film-forming dressing tool for descaling and removing steel from steel.

So far, steel stock has been descaled and ro et-free by pickling, usually using a dipping process. While When immersing small-dimensioned workpieces, no significant difficulties arise, however, when immersing large-dimensioned steel goods, a large (immersion) space is created »© how large amounts of pickling solution are required, which increases the pickling costs very much ·

It is also known that pickling is carried out using a spraying process to undertake. Since the amount of pickling solution is insufficient and the pickling solution dries up, the pickling solution must be sprayed on repeatedly in order to supply a sufficient amount of pickling solution to the steel material to be descaled and / or rustproof. In addition, the spray heating as such is cumbersome.

Finally, a pickling process is also known in which a pickling compound in the form of a paste with an additive on a powdery organic or inorganic thickeners the surface of a steel sheet is applied. This verse

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• Driving, however, has the disadvantage that the distance of the thickener from the pickled standing surface is time consuming and expensive.

The invention was based on the task of a pickling compound indicate, with the help of which simply apply the üasse on the steel rod to be pickled and then pulling it off of the peelable (by chemical reaction) formed Films (coating) τοη the steel surface without final Wash with water, without neutralization and without post protection treatment a perfect and cheap Beizunp; reach leaves.

It has now been found that this object can be solved with a peelable film-forming etching mass of descaling stainless υηα making steel material, which i * ¹ consisting essentially of sodium alginate or sodium alginate, and gelatin; at least one further additive consisting of starch, a water-soluble synthetic resin, bentonite, talc, powdered silicon dioxide and powdered, activated terra alba; an acid in liquid or solid form;

The pickling compound according to the invention can be used, for example, for "descaling or rustproofing ships, large-dimensioned ships Use tanks, bridges and other steel structures.

In the preparation of a pickling compound according to the invention, sodium alginate, which gels in the reaction with the acid contained in the pickling compound and the iron on the steel surface to be pickled to form iron, and gelatin, which is characterized by the property that when the pH of the mass is lowered to 3 to 5 as a result of the conversion between the , JJ ^ j ₁ - * fj * ··? -. «" ■ ■

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ORfGfNAt.

Acid and iron quickly gelled, mixed in a filament-forming base mass, Troreuf the base mass obtained -vit at least. Another component, consisting of starch, a water-soluble, synthetic resin, such as polyacrylamide, methyl cellulose, carboxymethyl cellulose sodium salt, alkyd resin, phenolic heart, melamine resin and acrylic resin, bentoriite, talc, powdered silicon dioxide and powdered, active terra alba, The base mixture obtained here is finally an acid in liquid form, for example a 15 to 20% strength by weight hydrochloric acid, sulfuric acid and / or, in particular, phosphoric acid solution, or an acid in solid form, for example one known as "ultraphosphoric acid" Polyphosphoric acid of the general formula Jtä

Dc with a molar ratio 0 \ x <1 or a phosphoric acid of the formula ^ + ^ η ^ Βη + Ι ^ ⁿ "^ * ^ * * ^and 5)» -in the wrestling of the acid (in the scale or remainder) promoting agent, For example, a non-ionic, surface-active agent, and optionally an agent which promotes the dissolution of iron, such as ammonium fluoride and tin (II) chloride, are added.

As already stated, the sodium alginate incorporated in the mass reacts with the iron salt, which in the reaction between the acid contained in the pickling mass and the iron on the Surface of the steel material to be pickled with gelation (of the pickling compound) to form iron alginate. The gelatin gels in a corresponding manner rapidly, when the mass, as a result of the reaction between the acid and the iron, has a pH of 3 to 5, in particular of 3 to 4, assumes.

The sodium elginate, when it is in dissolved form, begins to gel at a pH value of 3 or below in the presence of Fe * ⁴ ions, while gelatin in the. mentioned pH values of 3 to 5 are used. If a pickling compound with these two components is applied to the surface to be pickled, the iron alginate and gelatin gel in the specified order, resulting in caking of the starch, water-soluble resin, bentonite, talc,

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powdered silicic acid and powdered, active terra alba components of the stain comes. In this way the stain becomes a film with a strong cohesive force. As already mentioned, these film-forming masses contain an acid in liquid form and have a long-lasting, 3 to 4 Rust-removing effect on the one to be pickled for hours Surface.

After the end of the pickling process, evaporation of the in the water contained in the pickling compound, gelation and caking of said constituents formed a continuous film of high tear strength. ' Therefore, when you pull this Film completely removes the rust on the surface to be pickled and achieves the desired pickling. The the Penetration of the acid promoting agent is used to pickle the liquid acid after the pickling compound has been applied Let the surface penetrate quickly into the rust; the means promoting the dissolving or bringing into solution of Bisen serves to reduce the dissolving effect of the acid on iron by reducing the Fe ** - formed in the liquid acid during pickling Ions to Fe ions to promote. The last two means mentioned are intended to accelerate rust removal.

When applying a pickling compound according to the invention to the Rusty surface of steel goods occurs initially as a result of the presence of the acid, with the rust being removed by dissolving the same for the formation of iron alginate; at the same time the increases The pH value of the pickling compound gradually increases so that a film is formed from the compound that becomes semi-solid when it dries. This movie can be removed from the stained surface without difficulty. After the film has been peeled off, the pickling is complete, a clean, rust-free metal surface being obtained. the The stain applied should be left on the surface for about 2 to 3 hours before the peelable film is formed is deducted.

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In the following, the invention will be based on a few recipes are explained in more detail:

Formula A

Parts by weight

Sodium alginate 6

Powdered gelatin 0.3

(water soluble) starch 20

20% strength by weight phosphoric acid solution 74 non-ionic surfactant

Medium 0.5.

The desired beiza & sse can be added to these components in the form of a paste by first heating the gelatin to a temperature of 50 ° to 60 ° C. Phosphoric acid solution dissolves and then the other components clogs under charges. The components mentioned can consist of commercially available products, with one Highest possible chemical purity of the products used should be.

Bezcptur B

Parts by weight Sodium alginate 10 Filtered Telkcui or Bentonite $ 0-80

15% by weight hydrochloric acid solution 70 - 100 non-ionic surfactant

Medium 0.5-0.5

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Recipe C

Parts by weight ITatr iumalgina t Powdered Talc or Bentcnite

15% by weight phosphoric acid solution 5% by weight hydrochloric acid solution non-ionic surfactant middle

50

40-6C

0.3 - G ₁ 5

Recipe D

Sodium alginate Powdered talc Powdered silicon dioxide 10 g aqueous sulfuric acid solution non-ionic surfactant

Parts by weight

3-5 50-80

3-5 120

0.3-0.5

In the case of recipes B, C and D, the same commercially available -; a tr iumalgina t used as in recipe 1; Instead of the surfactant sold under the trade name THtSUBI 1-125 used in formulation 1, a non-ionic surfactant sold under the trade name PU3UEP 1-210 was used in formulations B, C and D. Powdered silicon dioxide is preferred either a colloidal or amorphous silica having a surface ψοη about 200 £ 50 m / β ^"w * ^{e they} are also commercially available, is used. The other components of recipes B, C and D aelian must also be of the greatest possible chemical purity.

The "recipes B, C and D are converted into a paste-like consistency, that the individual ingredients are

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BATH ORIGINAL

impresses with sufficient stirring in the respective acid solution,

Formula E

Sodium alginate

Powdered silica 15 wt% phosphoric acid solution 5% by weight nitric acid solution non-ionic surface-active middle

Formula F

Parts by weight 3 - 20 - 40 - 40 - - 5th - 40 - 60 - 60

0.3-0.5

Parts by weight

Sodium alginate

Powdered silicon dioxide Powdered, active terra alba 15% strength by weight phosphoric acid solution 5% by weight hydrochloric acid solution non-ionic surfactant middle

15th 15th 40 40

60 60

0.3-0.5

The formulations B and P can be prepared in the same way as the formulations B ₁ C and D using just as pure commercially available ingredients.

Recipe G

Sodium alglnate

Powdered silicon dioxide Powdered, active terra alba

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Parts by weight 3 - 15 - 15 - - 5th - 25th - 25th

^H Ultraphosphoric ^{Acid M} 5-20 (Acid) -Awmonium Fluoride 1-5 Powdered- Nonionic Surfactant 0.3-0.5

To produce a pickling compound according to the invention, the components mentioned are mixed with one another and in a Mill homogeneously finely divided} the pickling mass is used in the form of a paste by adding 40 - 80 parts Water can be added. As a non-ionic surface-active agent in the present case, for example, those under the

rr "-, τ. · ^ "" -R "-n" T - "* _ηΛ · _ρ Λ" .τ r ^ .vertriebenen Hetznittel Handelsbezexchnungen SOLGEF be 50 or SOLGBN 70 / used.

Formula H

Parts by weight

Sodium Alginate 3-5 Powdered Silica 15-25 Powdered ·, active terra alba. 15-25 5-10 polyphosphoric citric acid '10-15 tin (II) chloride 1-3 Powdered non-ionic surfactant 0.3 to 0 _t 5

For the production of a pickling axis according to the invention the mentioned ingredients in the same way as for the recipe G mixed and ground. The pickling compound is after adding 40 - 80 wt .- ^ water ready for use with stirring. The addition of tin ions is used to bring iron into solution; in the same Like tin (II) chloride, metallic tin, tin (II) oxide can also be used or tin (II) sulfate can be used.

The formulations G and F, initially obtained in powder form

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can be stored and transported in an advantageous manner; by adding water they are readily converted into a ready-to-use one Form transferred.

Steel surfaces that have been treated with a pickling compound according to the formulations B> F »G and H do not have to be post-treated. eg neutralized or subjected to a rust protection treatment *; In addition, it is advantageously up to about 7 TJeine Tageanach pickling self-standing can not be in air at a temperature of 20 ⁰ C and a humidity of 755 to & Eostbildung. After the pickling process, such steel surfaces can be painted or varnished.

The following examples are intended to illustrate in more detail the advantageous use of pickling compositions according to the invention.

The pickling compounds used in the following examples were each made by mixing the individual formulations specified ingredients in amounts that the agent between the respective lower and upper limit of the individual components make up "&", manufactured·

example 1

The pickling bases prepared according to formulations A, B, C and D were individually applied with the help of a brush to a thickness of 2 to 3 μm on the surface of 6 and 12 mm thick steel sheets, which had mill scale on their entire surface and leave it on for 2 to 3 hours at room temperature. A semi-solid film was formed from each of the pickling corns applied in the manner described. The continuous film could be peeled off in one piece without difficulty, revealing a clean metal surface on the steel sheet. The exposed metal surface was then washed with water, neutralized and treated for rust protection with a 1% strength by weight aqueous ifodium nitrite solution

math 3-day storage (inside a building) was the

• ·

- .10 -

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BATH

Metal surface painted with an epoxy varnish. After the Was leak dried, the metal sheet was left outdoors for 1 year; the condition of the painted surface was satisfactory; between this painted surface and the surface of a steel sheet, which with the help of a sandblasting fan was polished and then varnished, no difference was found.

BeisOJel 2

The pickling compositions obtained according to the formulations E, F, G and H were each in the manner described in Example 1 on 12 mm thick sheet steel on its tresaat surface ^ alcinder was applied. After removing each The film formed was exposed as in Example 1, a clean, bare metal surface.

The stained surface was then simply cleaned with a clean «! Cloth wiped with an an alkyd resin, chlorinated rubber, an epoxy resin or a coal tar / epoxy resin al ,? Varnish containing soupt carrier and finally 7 days Ibng dried. The painting was then done using the cross-cutting method examined for their adhesive strength. The eaex investigation showed that no steel sheet was painted could be withdrawn. The painted sheet steel surface was also immersed or immersed in 3% salt water for 3 months. Sprayed with a 5% salt water for a month resulted in calibration between that with a pickling compound according to the invention treated and painted steel sheet surface and the surface of one treated with a sandblasting blower and then painted steel sheet no difference

-11.- 109830/1785

Claims (1)

Claim Removable, film-forming pickling compound for descaling and rustproofing steel goods, consisting essentially of sodium alginate or sodium alginate and gelatine; at least one further additive consisting of starch, a »water-soluble synthetic resin, bentonite, talc, powdered silicon dioxide and powdered, activated terra alba; of a bull in liquid or solid arm; an agent that promotes the penetration of the acid (into the scale or rust) and possibly an agent that promotes the dissolution of iron. 109830/1785 '^ n OFiföJNAL