DE3837794A1 - Process for producing an anticorrosion composition for steel reinforcements, based on aqueous dispersions - Google Patents

Abstract

The invention relates to a process for producing an anticorrosion composition for steel reinforcements in autoclaved silicate concretes, based on aqueous dispersions. Starting from a thermoplastic polymer dispersion based on polyvinyl compounds, such as a carboxyl latex dispersion of the copolymer of an alpha , beta -vinylidene carboxylic acid, butadiene and styrene or of a styrene acrylate dispersion of the copolymer of an acrylic ester and styrene, and from bitumen, coal-tar pitch and clay with water-soluble additives such as cellulose derivatives, polyalcohols, stearates, pigments and inhibitors, in accordance with the invention the known thermoplastic polymer dispersion is neutralised with sodium hydroxide and stabilised, and homogenised at a pH of 8 to 9 with the known mixing components comprising bitumen or coal-tar pitch, clay, water, the soluble additives and with 0.25 % by mass of a mixture of sodium hydroxide and sodium carbonate, the ratio of sodium hydroxide to sodium carbonate being 1:0.8.

Description

field of use

The invention relates to a method of producing a corrosion inhibitor autoclaved for steel reinforcements Silicate concrete.

Characteristic of the known state of the art

There are corrosion protection systems for steel reinforcements especially for autoclaved silicate concrete known (DD WP 69 170, DD WP 2 32 164, DE 35 19 884, CSSR EB 2 06 067, SU EB 8 67 895). DD WP 2 32 164 includes a corrosion inhibitor consisting of an organic polymer dispersion based on polyvinyl compounds, an organic high polymer such as cyclohexanone-formaldehyde resin, bitumen, coal tar pitch and polyvinyl butyral with a melting interval of 70-160 ° C and other organic and inorganic Additives, such as water-soluble cellulose derivatives, melamine-formaldehyde condensates, Alkylphenylpolyglykoläther, clay, pigments, inhibitors composed. The polymer dispersion used is a styrene acrylate dispersion based on a copolymer of acrylic acid and styrene or a carboxylatex dispersion of the copolymer of an α-β- vinylidenecarboxylic acid, butadiene and styrene.

The latices underlying these dispersions are liable for the special use of the disadvantage that they after the Polymerization process with primary, secondary or tertiary Amines or neutralized with ammonia and stabilized.

The alkalinity of the anticorrosion agent necessary for the passivation effect, which by alkaline reacting pigments or Ca (OH) ₂ or NaOH is achieved caused a strong and uncontrolled foaming during production the composition.

Foaming is caused by a strong NH₃ development, this in turn is caused by a displacement reaction or aminolysis of the amines contained in the latex or Ammonia due to the presence of strong alkaline components.  

The stable foaming in the aqueous corrosion inhibitor is the cause of existing pores up to a diameter of 80 μm of the applied film on the steel surface. In In extreme cases, the applied protective film shows channeling to the steel surface, causing the corrosion protection order itself questioned.

The gas evolution or foaming according to the above principle is increasingly involved in the thermoplastic protective film elevated temperature and the highly alkaline medium of silicate concrete at about 185 ° C on. The pore structure is thereby increased.

Another disadvantage after o. G. Patent produced corrosion inhibitor This is not exactly the consistency to be able to adjust. Alone with the thickener is clay the required homogeneity can not be achieved. The required Layer thickness of the applied coating can therefore only be achieved with a two-time job.

Object of the invention

With the invention, a corrosion inhibitor to liquid Dispersion base can be prepared with alkaline Pigments and additives does not cause gas evolution and by appropriate composition the required Layer thickness is achieved in a single dipping process.

Essence of the invention

The invention has for its object to provide a method for To develop a corrosion inhibitor, with despite alkaline pigments and filler components production, processing and autoclave treatment no gas evolution occurs and an exact Konsistenzeinstellung allows, so that with a unique coating the protection of the steel is ensured.

With a thermoplastic polymer dispersion based on a Karboxyllatexdispersion of the copolymer of an α-β- vinylidenecarboxylic acid, butadiene and styrene or a Styrenakrylatdispersion of the copolymer of an acrylic acid ester, styrene and butadiene, and additions of bitumen or coal tar pitch, clay and water-soluble components in cellulose derivatives, polyalcohol , Stearates, pigments, inhibitors, the object is achieved in that the known elastic or thermoplastic polymer dispersion stabilized with sodium hydroxide and "neutralized" to a pH of 8-9 "and with the known mixing ingredients, such as bitumen or coal tar pitch, clay , Water, water-soluble additives such as cellulose derivatives, polyalcohols, stearates, pigments, inhibitors and homogenized with 0.25 parts by mass in% of a mixture of sodium hydroxide and sodium carbonate, wherein the ratio of sodium hydroxide to sodium carbonate 1: 0.8 be wearing.

The mixture components are in the following proportions ground together in a ball mill:

Elastic or thermoplastic polymer dispersion: bitumen or coal tar pitch: clay: water: water-soluble additives : NaOH / Na₂CO₃ = 1: 1.20: 0.2: 0.85: 0.005 / 0.004. By neutralizing and stabilizing the alkali and heat-resistant polymer dispersions by means of sodium hydroxide Foaming due to gas evolution is excluded. The mixture of sodium hydroxide / sodium carbonate increases the viscosity after the preparation of the corrosion inhibitor mixed in. This makes it possible that in the single coating process a non-porous, well-adhering corrosion protection film can be applied. Sodium hydroxide and sodium carbonate enhance the passivity properties of the anticorrosion agent.

embodiment parts by weight 1. NaOH-stabilized and neutralized latex VP 6263 28.2 2. Water 23.8 3. bad luck 33.42 4. carboxymethylcellulose 0.08 5. Stabilizer 1216 0.18 6th tone 5.50 7. Butyl polyglycol 0.28 8. Surfactant N 0.02 9. polyvinyl alcohol 0.01 10. Polyacrylic salt AN 0.14 11. Calcium stearate 3.16 12. Lead II oxide 4.94 13. Fatty alcohol KR 0,018 14. Sodium hydroxide 0.14 15. Sodium carbonate 0.112

Claims (2)

1. A process for the preparation of a corrosion inhibitor for steel reinforcements autoclaved silicate concrete with a thermoplastic polymer dispersion based on polyvinyl compounds, such as a Karboxyllatexdispersion of Kopolymerisates of an α- β -Vinylidenkarbonsäure, butadiene and styrene or a Styrenakrylatdispersion of the copolymer of an acrylic ester. Styrene, with bitumen, coal tar pitch, clay and water-soluble additives, such as cellulose derivatives, polyalcohols, stearates, pigments, inhibitors, characterized in that the known elastic or thermoplastic polymer dispersion is neutralized and stabilized with sodium hydroxide, at pH 8-9 with the known mixture constituents Bitumen or coal tar pitch, clay, water, the water-soluble additives and is homogenized with 0.25 mass% in a mixture of sodium hydroxide and sodium carbonate, wherein the ratio of sodium hydroxide to sodium carbonate = 1: 0.8. 2. The method according to claim 1, characterized in that the Blend ingredients in the pulp ratios thermoplastic polymer dispersion: bitumen or coal tar pitch : Clay: water: water-soluble additives: NaOH / Na₂CO₃ = 1: 1.2: 0.2: 0.85: 0.005 / 0.004 with each other be ground.