Get instant access to Acronal® D technical datasheet. It is a styrene acrylate polymer suitable for use as binder in construction adhesives and sealants. Get instant access to Acronal® D technical datasheet. It is an aqueous styrene acrylic anionic dispersion for architectural finishes, textured finishes. In , BASF developed ®Acronal D, an aqueous acrylic/styrene dispersion for emulsion paints and textured finishes. At that time, very few people could.
|Published (Last):||8 August 2007|
|PDF File Size:||7.8 Mb|
|ePub File Size:||11.67 Mb|
|Price:||Free* [*Free Regsitration Required]|
The present invention relates to anticorrosive coating compositions in aqueous phase. Acronnal especially relates to such compositions, free from toxic pigment containing tungsten, chromium in oxidation state VI, lead, molybdenum or boron.
The compositions according to the invention are useful for coating metal elements including iron, particularly ferrous metal parts in the automotive industry to provide protection against corrosion. ART Most anticorrosion paints available on the market today include two-component epoxy or alkyd binder, one or organic solvents and one or anticorrosion pigments such as zinc chromate or strontium metaborates or phosphates.
These paintings do not allow to respect fully or easily environmental constraints mainly due to the presence of organic solvent. Furthermore, many studies on the use of aqueous coating compositions as anticorrosion primer on steel, has been made. These coatings are formed by drying and optionally curing the applied composition. The difficulties 20 formulating corrosion High performance compositions from aqueous polymer dispersion are still highlighted by ZW Wicks, Jr.
Such coating compositions usually comprise an aqueous dispersion of a film-forming polymeric x, one or more corrosion inhibiting pigments, and optionally one or more additives, for example thickener. Among them, many compositions generally have at least one of the following disadvantages: Thus, through the European patent EP-Baqueous anticorrosion paints are known comprising: Such paints which can be applied and dried at room temperature, aim to eliminate the risk of instantaneous formation of rust.
Instability including storage has not been described as a problem in such aqueous anticorrosion paints. However, in practice it has been observed that certain aqueous dispersions of film-forming polymer, such as acrylic polymers are generally unstable at acidic pH and flocculate at these pH.
Other documents also disclose aqueous anticorrosion paints based on dispersions of acrylic co polymer modified or not. So that the polymer dispersion is stable overlooked metal ions, particularly those inhibitors pigments from corrosion, this patent recommends the addition of a system of two specific emulsifiers on their chemical nature, in proportions ranging from 0.
If the stability of these anticorrosion paints is satisfactory, however their term corrosion performance is average. When they are applied to sheet metal construction tinplate degreased, so as to obtain a thick dry layer 50 to 80 microns after drying for 3 days at room temperature, results of salt spray test according DIN 50 standard lead adronal a fairly rapid onset of rusting: In fact, a significant number of paintings covered by EP demand lead to unsatisfactory results in terms of corrosion.
It has now been unexpectedly discovered that by employing a combination of a particular class of acrylic binders, a class of special non-toxic anticorrosive pigments and additives appropriately aceonal, it is possible to prepare compositions anticorrosion coating in the aqueous phase having all of the advantages a – f below:.
B – forming coatings on ferrous substrates without immediate corrosion phenomena when they are dried at room temperature. C – forming coatings on ferrous materials having hardnesses up to approach those obtained with the anti-corrosive paint containing an alkyd or epoxy bicomponent binder and one or more organic solvents in the conditions of the standard NF T December As part of the invention, the hardness of the anti-corrosion coatings are advantageous-ing adaptable depending on the intended application.
D – formation of coatings on ferrous materials having a resistance to satisfactory saline mist s approaching that obtained with the anti-corrosive paint containing an alkyd binder or epoxide bicomponent and one or more organic solvents, and in some cases, equal or higher in the conditions of the ISO standard.
Specifically, the required salt spray damage as part of the present invention are generally in the conditions of the above standard:.
Acronal D: A binder for textured finishes. | Article Information | J-GLOBAL
E – formation of coatings on ferrous substrates with adhesion of the metal support at least equal to those obtained with the anti-corrosive paint containing an alkyd or epoxy bicomponent binder and one or more organic solvents in the conditions of NF T of November. F – for forming coatings on ferrous substrates with good strength and held when it is immersed in demineralised water.
The present invention therefore xcronal to anticorrosive coating compositions, aqueous phase having a basic acrobal and characterized in that they essentially comprise: In addition, according to an essential feature of the present invention, the hydrophobic film forming binder, therefore capable of favorably influencing the water permeability of the dry film of the anticorrosive coating must meet the test conditions. The present invention also relates acroal the use of compositions for the protection of metal elements comprising iron in various fields of activity such as automotive and construction.
Advantageously, thanks to the anticorrosive coating composition according to the invention, it is not necessary to add other film-forming binder, such as an epoxy ester, to achieve high performance of the corrosion resistance.
Another essential component of the compositions according to the present invention is an anticorrosive pigment forming compounds with iron II and III ions which are very sparingly soluble or insoluble in water.
The anticorrosion pigment is selected from non-toxic compounds, preferably from the group consisting of: Advantageously, the anticorrosion pigment used in the context of the invention preferably contains one or more sparingly soluble oxides in water e alkaline such as zinc oxide or aluminum oxide. Among the anti-corrosive pigments which led to the highest performance in resistance to saline mist, when they are associated with the aforementioned components a – foptionally g selected include:.
As indicated above, the present invention avoids the use of toxic anti-corrosive pigments. Examples of toxic anti-corrosive pigments that are recommended not to use include chromates, molybdates, lead oxides, pigments containing a metal such as tungsten, lead, and boron compounds. Also, some well known anticorrosive pigments of the art such as pure zinc phosphate are not recommended in the compositions of the present invention because the performance which they lead are not satisfactory.
Thus, the adhesion of coatings containing pure zinc phosphate as an anti-corrosion pigment on ferrous substrates is poor and the corrosion resistance of such coatings is also poor. The maximum particle size of the anticorrosion pigment must obviously be less than the thickness of the dry film It is advantageously chosen as low as possible as well, the corrosion resistance is better. Preferably, the maximum size of the grains constituting the anticorrosion pigment is 30 microns.
Another essential component of the compositions according to the present invention is a corrosion-inhibiting agent also called “anti flash-rusting agent” whose main function is to acgonal the immediate corrosion phenomenon also known as “flash-rusting” without wherein a varnish of the type used in the test a for selecting the film-forming binder, is colored in brown instantly. Preferably, the corrosion inhibitor is capable of modifying the time to attack by corrosion of a ferrous metallic article with an aqueous hydrochloric acid solution.
To verify the efficacy of the compound selected, the procedure is preferably to test C below:.
Acronak sponge of the metal acid attack causes the appearance of bubbles of hydrogen on aconal surface of the sponge. It quickly rises to the surface: In the context of experiments conducted by the Applicant, the reference rise time, tr, was 8 seconds. In contrast with the anticorrosion pigment which is solid and practically insoluble in water, the corrosion inhibitor agent is soluble in water.
Compounds having a corrosion inhibiting activity are well known in the art. For example corrosion inhibitor suitable for the preparation of compositions according to the invention, reference may usefully in Table II contained in the part concerning the embodiments, retaining preferably those having led in the test of the frame Ca rise time of the upper metal sponge to that obtained in the control test.
Also, to better meet environmental constraints, it is recommended to avoid the use of toxic corrosion inhibitor, such as those containing nitrites. The corrosion inhibitor content is preferably limited since, due to its solubility in water, a too high content may increase the sensitivity of the dry dd water. Therefore, it is advantageously between 0. The compositions according to the invention also contain at least one dispersing acrpnal if this function is not provided by another component of the compositions according to the invention.
Search Import Export Data of India
This agent is primarily used to deagglomerate the anti-corrosive pigments and various other solid additives may be present in these compositions. Acroal dispersants may be used in the present invention are well-known products of the art. Examples of dispersing agents acdonal suited to the invention, there may be mentioned: The dispersant content is preferably between 0. The compositions according to the invention also contain at least e antifoaming agent.
The anti-foaming agents that may be used in the context of the present invention are well-known products of the art. Examples of antifoam agents include polysiloxanes copolymers, acornal and mineral oils. The content of the antifoaming c is preferably between 0. The compositions according to the invention also contain at least one coalescing agent whose primary function is to promote the rapid formation of a dry film.
Coalescing agents that may be selected are volatile chemical compounds in the film forming conditions, which then progressively remove the dry film as opposed to the plasticizers which are low volatile compounds under the conditions of the art in question but which are likely to exude to the r of the dry film by incompatibility therewith and therefore compromise its adhesion to topcoats.
Preferably, the coalescing agents chosen as to acrnal an anticorrosive coating composition to be air dried, have a low boiling point and high vapor pressure to promote s final properties of the film. For these reasons, in the case of an air drying or forced air, it is recommended not to use, in particular the 2,2,4 trimethyl 1,3 pentane diol boiling point: Examples of coalescing agents suitable for the invention include glycols, ethers and glycol esters and paraffinic compounds.
According to the invention, the anticorrosive coating compositions in aqueous phase have a basic pH: Preferably, it is between 8 and 9. If necessary, to achieve a basic pH, is added to the compositions according to the invention a pH regulator or neutralizing agent. Advantageously, to further improve the performance screw c corrosion, water is used free of soluble salts, such as distilled water, demineralized or deionized.
However, satisfactory performance is achieved with the urban water distribution network. The compositions according to the invention may contain, advantageously, at least one water repellent agent or hydrophobic compound whose primary function is to enhance the hydrophobicity of the dry film. Indeed, under these conditions, the corrosion resistance was further improved ie resistance to salt spray according to standard ISO and held in deionized water by immersion for hours according to the test method D27 September entitled “paint coatings – the immersion resistor in water Ford tray and prescribed for Peugeot and automobiles Citroen.
Examples of water repellent agent include polyethylene waxes, polypropylene waxes, polyamide waxes, polysiloxanes, silanes and mixtures formed with the aforementioned waterproofing agents. Preferred hydrophobizing agents r selected from polysiloxanes and silanes. The aforementioned waterproofing agents are optionally in the form of aqueous emulsion.
The compositions according to the invention may also contain, advantageously, finely divided mineral fillers. By finely divided inorganic fillers is meant fillers with a maximum grain size not exceeding 30 microns, preferably less than or equal qcronal 5 microns. Mineral fillers that may be used are well-known products of the art.
Examples of inorganic fillers include: However, it is recommended not to use mineral fillers can cause significant acdonal of air, such as talc, which can lead, by the inclusion of air bubbles, the formation of defects in the film as micropitting and thus increase the risk of rusting on these defects. Preferably, use is mica, wollastonite and micaceous iron oxides. Acronxl mineral filler content may vary within wide limits: The compositions according to the invention may also contain various additives conventionally used in the field in avronal, such as: Preferably used polyurethanes, associative acrylic polymer or a combination of these two compounds.
However, it is recommended not to use thickening agents having a strong power of water retention, such as cellulose ethers, because of the sensitivity to water corrosion coatings so prepared. However, it should not be introduced in the compositions according to the invention, the agents capable of promoting, significantly, the dissolution of iron II and III ions such as certain emulsifiers and water-soluble agents capable of increasing the water absorption of the film.
Protective coating compositions according to the present invention are advantageously presented, prior to use, as a single component.
As indicated above, the carriers contemplated for anticorrosive coating compositions of the present invention are varied. As another example, it may also be made degreased steel supports or blasted steel or steel iron phosphate or zinc phosphate or chromate.
The compositions according to the invention can be applied for example by dipping or casting, brushing, using an applicator bar or spray gun. The drying conditions after application, can be varied and determined depending on the chemical nature of the film-forming binder and its ability to form a dry film.
Thus, drying can be carried out naturally in air or by forced air to a temperature above room temperature e. On the anticorrosive coating compositions of the present invention, once the deposited film is dry, one can apply one or more finishing layers provided that they are compatible with the protective film of the corrosion. Other advantages of the compositions of the invention will become clearer on reading the examples below.
I – Selection of film-forming binders suitable for preparation of anticorrosive coating compositions according to the invention. The film-forming binders used and the results obtained are listed in the table I below. Attack time was determined by corrosion in the test conditions C described above to quantify the effectiveness of chemical compounds as a corrosion inhibitor.