Metallic substrate coating composition

FIELD: protective coatings.

SUBSTANCE: invention relates to undercoat for metallic substrates designed for manufacturing articles and for applying top coating layers. Undercoat comprises silicate binder containing aqueous silica sol having SiO2/M2O molar ratio at least 25:1, wherein M represents sum of alkali metal ions and ammonium ion, silica particles having average size above 10 nm. Binder may further contain insignificant amount of alkali metal silicate. Content of solids in undercoat ranges between 20 and 40% (v/v) and volume ratio of pigment concentration to critic concentration thereof is below 1. Undercoat contains following proportions of components aqueous silicate sol as binder having SiO2/M2O molar ratio at least 25:1 and pH value between 9.5 and 11, wherein M represents sum of alkali metal ions and ammonium ion and silica particles are optionally modified with aluminum oxide and have average diameter 10-16 nm; 10-55% zinc and/or zinc alloy powder based on the weight of dry film having average particle size between 2 and 12 μm; 0-35% organic resin based on the weight of dry binder; and 0-30% organosilicon finishing material. Coating may contain zinc-free pigment(s) and filler increasing storage life time of undercoat. Method of applying undercoat onto steel substrate comprises preparing undercoat using silica sol, whose pH is adjusted to 9.5-11, and depositing undercoat onto steel substrate.

EFFECT: increased hardness and wear resistance, and enabled deposition of corrosion-resistant coating without blistering.

15 cl, 10 tbl, 14 ex

 

This invention relates to a composition for coating, which can be used for coating metal substrates, such as steel substrates. Specifically, it relates to compositions for coating for steel semi-finished products, of which then produce the products by means of high heat intensity and cause additional coverage. Such steel semi-finished products used in the shipbuilding industry and for other large-scale structures, such as platforms for oil extraction, and include steel plates, for example, a thickness of 6 to 75 mm, rods, beams and various steel profiles are used as rigid structural elements. The most important way with high thermal intensity is welding; almost all such steel semi-finished products are subjected to welding. Other important ways of handling the high heat intensity are cutting, for example oxy-flame cutting, plasma cutting, laser cutting, and shaping of, when the steel bend when heated, giving the desired shape. These steel products are often exposed to weather conditions before and during construction, and are usually applied coating, which is called "factory primer" or "pre-coating" in order to prevent corrosion of steel, to ora occurs before as the design of steel, for example, a ship, a fully coat with anticorrosive paint, thereby avoiding solving the problem of applying a protective coating or removal of corrosion products of steel. Most of the major shipyards primer exercise as one of several types of processing on the production line, for which steel, for example, pre-heated, put sand or shot peened to remove scale and corrosion products, apply primer and passed through the drying unit. There is also a variant in which the primer causes the seller or supplier of steel before joining her at the shipyard or other place of construction.

While the main goal of applying the factory primer is to provide temporary corrosion protection during construction, for shipbuilders preferably, the primer should not be removed, and it could remain on the surface during and after production. Therefore, it is necessary to allow welding to steel with factory applied primer, without removing it, and apply it to various types of protective anti-corrosion coatings, commonly used for ships and other steel structures, with good adhesion between the primer and applied vpos is estii coating. Steel coated with a primer coating preferably should be suitable for welding, and this coverage should not degrade the quality of welding or slow down the speed of the welding process, in addition, the primer coating must be sufficiently heat-resistant to retain its anti-corrosion properties in areas heated while giving a streamlined shape or welding the opposite side of the steel.

Successfully manufactured primer coatings currently available are coatings, solvent-based pre-hydrolyzed tetraethylorthosilicate binder and powdered zinc. These coatings have a high percentage of volatile organic solvent, typically about 650 grams per liter, in order to stabilize the binder of the paint and allow the coating in the form of a thin film, typically a thickness of about 20 microns. The volatile organic solvent can have a harmful impact on the environment, and in many countries, such effects are regulated by law. There is a need for a primer coating, which not emit volatile organic solvent or makes it much less. Examples of such coatings are described in applications for U.S. patent US-A-4888056 and Japan JP-A-7-70476.

Application JP-A-6-200188 relates to a primer coating and indicates the possibility of application of the binder in the aqueous alkali metal silicate. Coatings containing aqueous alkali metal silicate and powdered zinc, also proposed in the applications GB-A-1226360, GB-A-1007481, GB-A-997094, US-A-4230496 and JP-A-55-106271. The alkali metal silicates as binders for anti-corrosion coatings specified in the application US-A-3522066, US-A-3620784, US-A-4162169 and US-A-4479824. In the application EP-A-295834 described coating containing a mixture of alkali metal silicate with a small amount of colloidal silicon dioxide powder of Al2O3as filler and metal powder as an additive improving impact strength. The authors of this invention have found that a primer coating based on an aqueous alkali metal silicate as a binder containing powder of zinc, can provide sufficient protection against corrosion and makes it possible to weld the steel surface, which caused these coatings, but when applying the next coating problems. Water silicates contain a large number of cations of alkali metals, necessary for the preservation of silicate in aqueous solutions, and these ions are retained in the coating after drying. The authors of this invention have shown that if these primer coatings containing large number is the number of ions of alkali metals, put any conventional organic coating, and then immersed in water, the formation of bubbles (local delamination of the coating). The authors conducted tests that showed that the problem can be reduced if the coating after application of the primer subjected to weathering for some time or wash before applying the next coating. However, these methods are not suitable for use on modern shipyards with high performance.

Aqueous silica sols with a very low content of alkali metal ions commercially available, but coverage on the basis of commonly used nuclei with large particles, as a rule, have a very low strength of the initially formed film from the viewpoint of adhesion, cohesion, hardness, abrasion resistance and water resistance. These are not good enough the physical characteristics of the coatings can be easily damaged in handling during further processing. This is the reason for the potential need of significant repair coating with large repair costs. Suggestions for improvement of coatings based on silica sols are described in the following applications: US-A-3320082 where add organic amine, which is not miscible with water, GB-A-1541022 where add acrylamide polymer, soluble in water, GB-A-1485169 where DOB is given in silicate Quaternary ammonium or alkaline metal, and in JP-A-55-100921, where it is proposed to add the clay and/or oxides of metals such as Al2O3and phosphate of aluminum and/or ethyl silicate. However, such coatings do not have the physical characteristics close to the characteristics of coatings based on alkali metal silicates. Coatings based on silica sols less bubbling away when applying the top coating/dipping into the water. Despite the low content of soluble salts and low osmotic pressure, bubbling still has a place because the floor because of his poor physical characteristics has a low resistance to the emergence/growth of bubbles.

There is a need in the factory primers, water-based with low content of alkali metal ions, with high adhesion to substrates and increased strength of the film to give it the properties discussed above, to resist the formation of bubbles and their growth. In addition, there is a need in the factory primer is water-based, which gives the floor, forming bubbles, with the rapid development of its physical characteristics after application that allows you to work with the substrate and further processing of the substrate without the risk of damaging the floor.

It was found that the ratio of the volume concentration of the pigment (PVC) to a critical volume concentration of pigment (CPVC)has a significant influence on the characteristics of the film. In addition, the pace of the film characteristics can be adjusted by adjusting the ratio of PVC/CPVC.

Bulk pigment concentration (PVC) is a pigment volume% in the dry paint film. The critical volume concentration of pigment (CPVC) is usually defined as the volume concentration of the pigment, which has such a sufficient amount of binder that provides a fully adsorbed layer of binder on the surfaces of the pigment and the filling of all gaps between the particles in a tightly-Packed system. The critical volume concentration of the pigment can be determined by soaking the dry pigment with so many of linseed oil, which is exactly enough to form a tight mass. This method gives a value known as the "absorption"of oil, from which it is possible to calculate the critical volume concentration of pigment. Method for determination of oil absorption is described in the British standard 3483 (BS3483).

In the application US-A-3721574 offers coatings containing a mixture of alkali metal silicate with minor amount of colloidal silicon dioxide, preferably, if this colloidal silicon dioxide modified Al2O3. Also mentioned coating containing a mixture of alkali metal silicate with minor to the number of colloidal silicon dioxide and zinc dust. In coatings modified with zinc, preferably a mixture of alkali metal silicate with a small amount of unmodified colloidal silicon dioxide. In the examples apply coatings with extremely high percentage of zinc dust. This leads to the formation of films, containing in the dry coverage of about 95% wt. zinc. However, such a high content of zinc has a negative impact on the suitability of the coating for welding. Consequently, these coatings are not suitable for use as a factory primers for steel semi-finished products, which are then subjected to give a streamlined shape or weld and cause them additional coverage. In the patent US-A-3721574 not provide any guidance on the relationship PVC/CPVC in the coating - any coating containing zinc, or for coatings that do not contain zinc. In this application, however, indicated that the ratio of PVC/CPVC has a significant influence on the properties of the films and on the speed of development of the film characteristics.

In international publication WO 00/55260 described composition for coatings containing silicon dioxide or silicate as a binder and the powder and/or a zinc alloy. Binder has a molar ratio of SiO2/M2O, where M denotes alkali metal ions and ammonium ions, of at least 6:1. This is the document approved, what is the volume concentration of the pigment in the coating should be at least equal to the critical volume concentration of pigment. To date, found that the characteristics of the film formed by the composition for coating, and the speed of development of these characteristics can be improved by using a composition for coating according to this invention, when the binder contains particles of silicon dioxide or silicate with an average particle size greater than 10 nm.

The composition according to this invention, which can be used for coating a metal substrate, intended for the manufacture of products and the overcoating is related PVC/CPVC less than 1. The coating includes a binder of silica containing silica Sol and optionally a minor amount of alkali metal silicate with an average particle size of the silica and/or silicate in the composition is greater than 10 nm. The molar ratio of SiO2/M2O in the specified binder is at least 6:1, where M refers to ions and alkali metal and ammonium. For purposes of this application a "minor amount of alkali metal silicate" means that the composition ratio of the mass of the silicate of an alkali metal to the weight of silica Sol is less than 0.5, preferably less than 0.25 and more preferably less than 0.1.

It was found that improved the diversified characteristics of the pre-coating can be obtained by using the coating with PVC from 35% to 65%, more preferably from 40% to 55%. In coating with PVC below 35%, which contains as a pigment only zinc, to maintain effective protection against atmospheric corrosion is not enough zinc, if you want protection for more than 6 months. When using coatings with a low zinc content, for example from 10 to 40%, acceptable corrosion protection can be obtained by adding one or more secondary corrosion inhibitors or adding a conductive filler, such as iron phosphide.

Primer coating preferably contains a powder of zinc, the average particle size of which ranges from 2 to 12 microns, and most preferably, when such powder zinc is an industrial product - zinc dust with an average particle size of from 2 to 8 microns. Powder zinc protects the steel by galvanic mechanism and may also form a protective layer of corrosion products of zinc, enhances corrosion protection, which provides coverage.

The entire powder zinc or its part can be replaced by zinc alloy. The amount of powder of zinc and/or zinc alloy in the coating is usually not less than 10% and can reach 90% of the volume of the coating, counting on dry film. Powder zinc and/or zinc alloy may be essentially all pigmentation of the coating, or may, for example, up to 70%, for example the EP, from 25 to 55% of the volume of the coating, counting on a dry film, and the coating also contains an additive corrosion inhibitor, for example, molybdate, phosphate, tungstate or Vanadate, as described in US-A-5246488; finely ground titanium dioxide, as described in detail in Korean patent KR №8101300, and/or zinc oxide, and/or a filler such as silicon dioxide, calcined clay, aluminum silicate, talc, barites, or mica. The amount of powder of zinc and/or zinc alloy in the coating is preferably from 35 to 60%, more preferably from 40 to 50%.

You can use other pigments in combination with pigments based on zinc. Examples of these other pigments that do not contain zinc include conductive fillers such as iron phosphide (Ferrophos®), micaceous iron oxide, etc. the Use of these conductive pigments which do not contain zinc, can make possible a reduction in the content of zinc while maintaining effective protection against corrosion. Order to obtain optimum performance of the coating is preferably used in compositions for coating sufficiently dispersed fillers. Types and sizes of used fillers can be adjusted to obtain the desired dispersion. For example, when choosing a filler pigment Satintone®(from Lawrence Industries), it is possible to use particles with an average size of less than 3 μm, the preference is sustained fashion than 2 microns.

The most preferred binder is a binder based on an aqueous silica Sol. Such sols are available, they are manufactured by Akzo Nobel under the registered trademark "Bindzil and DuPont under the registered trademark "Ludox", although in the literature on such sols emphasizes that the commonly used grades of colloidal silicon dioxide are not a good film. There are various varieties of Zola with different particle sizes of colloidal silicon dioxide and containing various stabilizers. The particle size of the colloidal silica may, for example, be from 10 to 100 nm; preferably, when the particle size is closer to the lower limit of this interval, for example, from 10 to 22 nm. In the compositions of this invention more preferably, if the binder, the average particle size of colloidal silica is from 10 nm to 20 nm, even more preferably from 10 nm to 16 nm.

Preferably, if the silicate ash molar ratio SiO2/M2O is at least 10:1, more preferably not less than 25:1, even more preferably at least 50:1, and the molar ratio of SiO2/M2O can be 200:1 or more. In addition, you can use a mixture of two or more of silica sols with different molar ratio of SiO2/M2O, where the molar ratio of SiO2 /M2O the mixture is at least 25:1. The Sol can be stabilized by alkali, for example sodium hydroxide, potassium or lithium, or a Quaternary ammonium hydroxide or water-soluble organic amine, such as alkanolamine. One example of such sols is the product Bindzil®3NH3/220-stabilized ammonium hydroxide, with low content of sodium, which is characterized by the following indicators: a Sol of silicon dioxide with a concentration of 30 wt.%, the average particle size of 15 nm, the molar ratio of SiO2/NH3about 30:1, the ratio of NH3/Na2O about 10:1 or more (30% wt. SiO2, 0,27% wt. NH3and <0.1% by weight. Na2O); pH 9,4; slightly turbid liquid of low viscosity with a distinct smell of ammonia; issued by the company Akzo Nobel (Eka Chemicals). Examples of other aqueous colloidal solution of silicon dioxide will be described below.

Silica Sol can be mixed with a small amount of silicate of alkaline metal such as lithium silicate, sodium silicate is lithium or potassium silicate or silicate ammonium, or Quaternary ammonium silicate. Other examples of suitable compounds (or compositions) can be found in U.S. patent No. 4902442. The addition of silicates of alkali metals or ammonium can improve the initial film-forming properties of silicate Zola, but the amount of alkali metal silicate should be the residual is small, so that the molar ratio of SiO2/M2O binder ash was at least 6:1, preferably not less than 8:1, and most preferably more than 15:1. For purposes of this application a "minor amount of alkali metal silicate" means that the composition ratio of the mass of the silicate of an alkali metal to the weight of silica Sol is less than 0.5; preferably, when it is less than 0.25, more preferably less than 0.1.

Silica Sol preferably has a low level of aggregation. It is possible to determine the value of specific surface area (S) for Zola. The value of S can be measured and calculated as describedVol.60 (1956), pp.955-975. The value of specific surface area S is influenced by the silicon dioxide content, the volume of the dispersed phase, the density and viscosity of silicate Sol. We can assume that the low value of the specific surface, S indicates a high degree of particle aggregation or attraction between particles. Silica Sol used in compositions for coating according to this invention, may have a value of S equal to 20-100%, preferably 30-90%, more preferably 50-85%.

Presently discovered that silica Sol with a low level of aggregation also gives very good results in the systems and methods described in the publications of international applications WO 00/55260, WO 00/55261, WO 02/22745 and WO 02/2276. For these systems, and methods silica Sol may have a value of S equal to 20-100%, preferably 30-90%, more preferably 50-85%.

Silica Sol may contain (alternatively or additionally) dissolved or dispergirovannoyj organic resin. The organic resin is preferably a latex, such as latex-based copolymer of butadiene and styrene, latex-based copolymer of butadiene and acrylic acid latex of a copolymer of vinyl acetate with ethylene, the dispersion of polyvinyl butyral, silicone/siloxane dispersion or latex dispersion based on acrylic acid. Examples of suitable dispersions of latex that can be used include XZ 94770 and XZ 94755 (both from Dow Chemicals), Airflex®500, Airflex®EP3333DEV, Airflex®CEF 52 and Flexcryl®SAF34 (all from Air Products), Primal®E-330DF and Primal®MV23 LO (both from Rohm and Haas) and Silres®MP42E, Silres®M50E and SLM 43164 (all from Wacker Chemicals). You can use water-soluble polymers, such as polymers of acrylamide, but they are less preferred. The organic resin is preferably used in amount up to 30 wt.%, more preferably, from 10 to 20 wt.%, dry binder. A higher content of organic resin may cause the formation of pores in the weld during subsequent the x welding works. It was shown in the result of measurement of adhesion by the method of cross-hatch test that adding organic resin improves the adhesion/cohesion.

Alternatively, the silica Sol may contain the agent linking the silane, which contains alkoxysilane group and an organic residue containing the functional group, for example, amino-, epoxy or isocyanate group. The agent linking the silane is preferably aminosilanes, such as gamma aminopropyltriethoxysilane, or gamma aminopropyltrimethoxysilane, or their partial hydrolyzates, although you can also apply epoxysilane, such as gamma glycidoxypropyltrimethoxysilane. The number of agent linking silane, preferably up to 30 wt.%, for example, 1 to 20 wt.%, counting on the dry binder.

Spanning primer coating may further comprise an aqueous solution of alkali metal silicate or ammonium silicate, stable siliconates, substituted with at least one anionic group with a lower PKa than that of silicic acid, such as carboxylate or sulphonate group. This binder is preferably a solution with a molar ratio of SiO2/M2O in the range of from 8:1 to 30:1 and a pH in the range from 7 to 11.5, which is prepared by lowering the pH of the solution of the silicate and siliconate by nationalwomen. So, siliconate can be added in relatively small amounts, for example, at a molar ratio of from 1:2 to 1:20, standard alkali metal silicate SiO2/K2O of 3.9:1. The solids content can then be reduced to facilitate processing and improve stability. At this stage the pH of the solution is 12-12,5. The solution is subjected to ion exchange using standard ion-exchange resin. Ions To+are replaced by ions of N+when this decreases as the alkali content in the binder, and its pH. Without the presence of siliconate silicate was gelatinous would with decreasing pH. Get transparent sustainable solutions with a pH of 8. The obtained binder typically has a molar ratio of SiO2/K2O in the range of from 8:1 to 20:1, and it can be concentrated, if required to increase the solids content. A binder is a transparent sustainable solution, which is stable in the presence of zinc, but the coating on the basis of these ion-exchange binding have relatively low strength of the film compared with the coatings on the basis of alkali metal silicates as binders.

It is preferable to use a binder with a pH of 9 to 11.5, more preferably a pH of from 9.5 to 11. Although the inventors do not wish to be bound by any theory, obyasnyau is th effect of pH on the properties of the film, it seems that the increased pH results in an increased number of ions of silicon oxide and/or silicate ions in solution. This, apparently, has the ability to influence the hardening of the gel in situ after application of the composition for coating. In addition, the regulation of pH may have a slight effect, increasing the viability of the composition. When used manufacture in the industry of silica Sol, it is possible to select the Sol with a high pH and/or pH of the Sol can be adjusted. You can bring the pH to the desired value, for example, by adding affecting the pH of the fillers that increase the viability (such as dimethylaminoethanol (DMAE) or diluted sulfuric acid), or by adding sodium hydroxide. For example, commercially available silica sols with particle size of 22 nm typically have a pH of about 8.5-9. The increase in pH of these sols to 10-11 significantly increases the speed of development of the characteristics of the coating.

The solids content in the primer coating is usually not less than 15% vol., and preferably from 20 to 35%. Volumetric content of dry substances is a theoretical value, which is calculated with respect to all components constituting the composition for coating. The coating usually has such a viscosity that it can be easily applied to conventional applicators is for coating, such as atomizers, especially airless sprayers and sprayers large amount of operating at low pressure (HVLP sprayers), and to obtain a coating with a dry film thickness less than 40 microns, preferably from 12-25 to 30 microns.

Composition for coating can optionally contain additional additives, well known to experts in this field, for example, thixotropy and/or agents that regulate the rheology (organic clay, xanthan gum, cellulose thickeners, polyurethane polyether urea, (pyrogenic) silica, derivatives of acrylic acid and the like), antifoaming agents (in particular, when there are modifiers latex) and optional fillers that increase secondary viability, such as chromates (e.g., sodium dichromate) or tertiary amines (e.g. triethylamine or dimethylaminoethanol). Preferred thixotropy and/or agents that regulate the rheology include Bentone®EW (from Elementis), which is a silicate of sodium-magnesium (organic clay), Bentolite WH (Rockwood), which is a water-aluminum silicate, Laponite RD (Rockwood), which is a water-silicate of magnesium-lithium, HDK®-N20 from Wacker Chemie), which is a pyrogenic silicon dioxide and Rheolate®425 (from Elementis), which is a proprietary acrylic dispersion in the de. Preferred antifoaming agents include Foamaster®NDW (from Cognis), Tego Foamex®88 (Tego Chemie) and Dapro®1760 (from Elementis). It was found that other agents that may be contained in the compositions for coating other reasons, can also act as secondary agents that increase the viability of the composition. For example, adding Molywhite anti-corrosion pigments or the best choice of latex (rubber) may cause a slight increase in viability. Preferred fillers that increase the viability, are tertiary amines, which give the possibility of increasing the viability without the use of chromates.

For systems that additionally contains aluminum oxide, also found increased viability. In this application, the concentration of alumina in the composition for coating is given as the percentage (wt.) Al3O3in the calculation of the silica Sol or silicate particles present in the composition. Order to obtain optimum performance of the coating, I prefer to use silica sols stabilized aluminum oxide, for example, silicate solu, modified aluminum oxide. In the sols modified aluminum oxide, the surface of the particles is modified sodium aluminate related the particles. Preferably, when the silica Sol modified aluminum oxide in amounts of from 0.05 to 2.5 wt.%, more preferably aluminum oxide in amounts of from 0.05 to 2.0% wt.

Usually the system for coverage offered in the form of two-component or multicomponent systems, where components are thoroughly mixed before coating. You can also prepare a composition for coating directly before coating, for example by adding and thoroughly mixing all of the components of the composition for coating just prior to its application. This method is also known as "online components are mixed in the composition for coating". This method is especially suitable for compositions for coatings that have limited viability.

The development characteristics of the coating can be accelerated further processing, where the substrate can be processed with a solution that increases the strength of the film primer coating. Preferably, if the metal substrate is applied primer coating according to this invention, and after drying the primer coating to such an extent that it was dry to the touch, it is treated with a solution that increases the strength of the film. This solution, which increases the strength of the film primer coating may generally be aq is m solution of inorganic salt or solution of a substance with reactive silicon-containing groups.

The development characteristics of the coating can also be accelerated by immersion is not necessarily processed substrate into the water or air is not necessarily processed substrate in an atmosphere with a humidity of at least 50%, preferably not less than 80%. Preferably, if the metal substrate is applied primer coating according to this invention and after drying of the coating to such an extent that it was dry to the touch, they are immersed in water or stand in an atmosphere with a relative humidity of at least 50%, more preferably not less than 80%. More preferably, if the metal substrate is applied primer coating according to this invention and after drying of the primer coating to such an extent that it was dry to the touch, it is first treated with a solution that increases the strength of the film, and then immersed in water or stand in an atmosphere with a relative humidity of at least 50%, more preferably not less than 80%.

Used in this application to describe the degree of drying of the coating, the term "to such an extent that it was dry to the touch", or until dry to the touch" is the standard adopted in English-speaking countries the technical term is"touch dry") and it means such a state of drying, when the weak (i.e. virtually the ski without clicking) the touch of your finger is already not felt sticky. Thus, this term corresponds to the term "drying to a tack-free", standard used for similar purposes (i.e. to characterize the degree of drying of the coating) in Russian literature in this field of technology.

When quick drying is not a problem, it is possible drying of the raw coating at low relative humidity, for example, with relative humidity of 25%to 50%. The development characteristics of the coating will occur more slowly, but eventually get a coating with good performance.

In a preferred embodiment of the invention, the composition for coating according to this invention is a factory primer water-based coatings on steel substrates, which are intended for the manufacture of products and the application of additional coverage, with a dry matter content of from 20 to 40% vol., where the ratio of the volume concentration to the critical pigment volume concentration of the pigment is less than 1, containing:

- binding of an aqueous silica Sol with a molar ratio of SiO2/M2O at least 6:1 and a pH of from 9.5 to 11, where M means as alkali metal ions and ammonium ions, and where the average particle size of silica, optionally modified aluminum oxide is from 10 nm to 16 nm,

from 10 to 55%. on osca zinc and/or zinc alloy with an average particle size of from 2 to 12 μm, calculated on the dry film,

from 0 to 35% wt. organic resin dry binder,

- from 0 to 30 wt.%. silicone sizing dry binder,

- optional pigment(s), not containing the zinc, and

- optional filler to increase vitality.

The invention will be explained with reference to the examples below. They are intended to illustrate this invention, but should not be construed as limiting the scope of his claims in any way.

Compounds used as starting materials in the examples are obtained from the following sources:

Ludox SMSilica Sol 30% (wt.) concentration, average particle size 7 nm, the molar ratio of SiO2/Na2O 50:1, from DuPont, pH of 10.3
Ludox HS-40silica Sol 40% (wt.) concentration, particle size 12 nm, the molar ratio of SiO2/Na2O 95:1, from DuPont, pH of 9.8
Ludox TM-40Silica Sol 40% (wt.) concentration, the average particle size of 22 nm, the molar ratio of SiO2/Na2O 225:1, from DuPont, a pH of 8.8
Bindzil 40/170Silica Sol 40% (wt.) concentration, average particle size 20 nm, the molar ratio of SiO2/Na2O 160:1, from Akzo Nobel (Ek Chemicals), the pH of 9.4
NyacolSilica Sol 40% (wt.) concentration and average particle size of 16 nm, a molar ratio of SiO2/Na2O 105:1, from Akzo Nobel (Eka Chemicals), pH of 9.8
Nyacol Aloption Nyacol, modified alumina, the pH of 9.9
XZ94770the best choice organic latex containing 50% by vol. dry matter from Dow Chemicals
Minex 20matricarialubricant filler with an average particle size 2,95 μm from the North Cape Minerals
Zinc dustmetal powder with an average particle size of 7 μm from Trident Alloys
Molywhite 212qualitycontrolled, antirust pigment with a particle size of 4.1 μm from Sherwin Williams
Bentone EWnitromagnesite, thixotrop from Elementis

In the experiment of silica sols used in the form in which they are received, i.e. the pH values listed above, unless otherwise noted. When you specify a pH different from the pH above the pH was adjusted as follows:

(i) pH Zola is brought to 9 by adding to the mix solu diluted sulfuric acid, the pH of which is equal to 1.5

(ii) pH of the Sol was adjusted to 10 by adding to the mix solu sodium hydroxide, the pH of which is equal to 14

(iii) pH Zola is avodat to 11 by adding to the mix solu sodium hydroxide, pH which is equal to 14

Example 1

To determine the effect of various PVC coatings containing silica Sol with a particle size of 12 nm and 40%. zinc in the dry film received several compositions, the concentration of solids was approximately 28%. The song, which was used in example 1C, was composed of the following ingredients:

Componentwt.%.
Ludox HS-4041,43
Water14,77
Zinc dust39,91
Bentone EW0,20
Molywhite 2122,11
Minex 201,58

Compositions for examples 1A, 1b, 1d and 1e with various PVC received, adding Molywhite 212 and Minex 20 songs, composed for example 1, or by removing them from this composition.

The obtained primer coating was applied to steel panels with a size of 15 cm (10 cm, and dry film thickness ranged from 15 to 20 μm at 35°C and a relative humidity (RH) of 30%. Primers (primers) were left for drying at a temperature of 23°C and 60% RH and were testing their physical characteristics after 1 hour, the next day after application. The results of these tests are shown in table 1.

Table 1
no experiencePVCΛMW 212Minex 20Mechanical properties after 1 h after applicationMechanical properties after 24 h after application
wet on wet abrasion resistanceThe pencil hardness scalewet on wet abrasion resistanceThe pencil hardness scale
1a400,56003<2B4<2B
1b450,655012<2B152B
1c500,725512<2B28B
1d550,80510222B602H
1e600,8851517B502H
1f701,0 52513HB302H

Example 2

To determine the effect of latex XZ 94770 in coatings containing silica Sol with a particle size of 12 nm and 40%. zinc in the dry film received several compositions, the concentration of solids was approximately 28%. A primer composition was obtained similarly to the compositions of examples 1A-1f. The content of the latex in all compositions, obtained for example 2 was 20%. in the calculation of the silica Sol.

The song, which was used in example 2, was obtained from the following ingredients:

Componentwt.%.
Ludox HS-4034,99
Water15,64
Zinc dust42,19
XZ 94770is 3.08
Bentone EW0,20
Molywhite 2122,23
Minex 201,67

The obtained primer coating was applied to steel panels with a size of 15 cm (10 cm, and dry film thickness ranged from 15 to 20 μm at 35°C and a relative humidity (RH) of 30%. Primers were left to dry at a temperature of 23°C and 60% RH and were testing their physical nature of the stick after 1 hour, the next day after application. The results of these tests are shown in table 2.

Table 2
no experiencePVCΛMW 212Minex 20Mechanical properties after 1 h after applicationMechanical properties after 24 h after application
wet on wet abrasion resistanceThe pencil hardness scalewet on wet abrasion resistanceThe pencil hardness scale
2a400,560014HB≫100H
2b450,6550262H≫1003H
2c500,7255>1002H≫1006H
2d550,80510>1002H≫1006H
2e600,88515/td> 652H≫1006H
2f701,04525252H>1004H

The comparison results are shown in table 2, the results of table 1 shows that the addition of latex to the composition can be improved film characteristics. The most rapid improvement in the characteristics of the coating is achieved with PVC from 50 to 55% wt.

Example 3

To determine the effect of increased content of latex coatings containing silica Sol with a particle size of 12 nm and 40%. zinc in the dry film received several compositions, the concentration of solids was approximately 28%. The volume concentration of the pigment in the primer compositions was 50%, which equals to 0.72 critical volume concentration of pigment.

The composition used in example 3A, was received from the following ingredients.

Componentwt.%.
Ludox HS-4041,43
Water14,77
Zinc dust39,91
Bentone EW0,20
Molywhite 2122,11
Minex 201,58

p> Compositions for examples 3b-3d was obtained by reduction of silica Sol and adding latex XZ94770 in increased quantities.

Conditions for application and curing of coatings were the same as in the above examples. Testing the physical characteristics of the primer was performed after 1 hour, the next day after application. The results of these tests are given in table 3. The amount of silica Sol and the latex XZ94770 are given as percentage (about.) in the dry film.

Table 3
no experienceThe content of silica Sol, % vol.The content of the latex XZ94770,

% vol.
Mechanical properties after 1 h after applicationMechanical properties after 24 h after application
wet on wet abrasion resistanceThe pencil hardness scalewet on wet abrasion resistanceThe pencil hardness scale
3a50012<2B28B
3b4010>1002H≫100 6H
3c3020752H≫1006H
3d2525903H≫1006H

Examples 4-7

Prepared a few songs Zola with particle sizes greater than 12 nm and a volume concentration of the pigment is 50% (Λ=0,72). All compositions contained 40% zinc, 5% Molywhite 212, 5% Minex 20 and 20% on. latex XZ94770 in the calculation of the silica Sol. In addition, one example for comparison (example 41) was carried out with a composition containing 70% PVC (Λ=1,06).

Conditions for application and curing were the same as in the above examples. The results are given in table 4.

Table 4
no experienceSilica SolThe particle size of ZolaMechanical properties after 1 h after applicationMechanical properties after 24 h after application
wet on wet abrasion resistanceThe pencil hardness scalewet on wet abrasion resistanceThe pencil hardness scale
4 16 nm35HB≫1003H
41Nyacol16 nm16HB47HB
5Nyacol Al16 nm30HB≫100H
6Bindzil®40/17020 nm10HB60HB
7Ludox®TM-4022 nm7<2B40H
1Example to compare

These examples show that for sols with particle size of 16 nm rapid development characteristics of the coating is achieved with PVC 50-55%. In addition, these examples show that the coating is deteriorated with the increase of particle sizes Zola.

Examples 8 and 9

Got two primer coating with a concentration of solids 28 vol.%, using a mixture of sols. The volume concentration of pigment in both the primer coating is 50%, which is equal to 0.72 critical volume concentration of pigment.

Primer coating used in example 8, was prepared from the following ingredients and got in the floor with the average time the leader of the particles Zola 10 nm.

Componentwt.%.
Ludox SM (7 nm)5,5
Ludox HS-40 (12 nm)29,6
XZ 947703,1
Water15,5
Bentone EW0,2
Zinc42,2
Molywhite 2122,2
Minex 201,7

Primer coating used in example 9, was prepared from the following ingredients and received a coating with an average particle size of Zola 10 nm.

Componentwt.%.
Ludox SM (7 nm)6,8
Nyacol (16 nm)30,0
XZ 947703,1
Water13,9
Bentone EW0,2
Zinc42,1
Molywhite 2122,2
Minex 201,7

The obtained primer coating applied to steel panels with a size of 15 cm x 10 cm, and the thickness of the dry film is from 15 to 20 μm at 35°C and a relative humidity (RH) of 30%. Within 1 hour of the coating is maintained at 60%RH. Then test their physical features is to 1 hour and one day after application. The test results shown in table 5.

Table 5
no experienceDimensions (particles) Zola in the mixMechanical properties after 1 h after applicationMechanical properties after 24 h after application
wet on wet abrasion resistanceThe pencil hardness scalewet on wet abrasion resistanceThe pencil hardness scale
87 nm/12 nm42HB≫100H
97 nm/16 nm28HB≫100N

The results in table 5 show that films with good characteristics can be obtained when using a mixture of sols.

Examples 10-13

Got a few songs with different pH and volume concentration of the pigment is 50% (Λ=0,72). All compositions contained 40% zinc, 5% Molywhite 212, 8% Minex 20 and 20% on. latex in the calculation of the silica Sol.

Used the same conditions for application and curing as in example 1. The results are given in tables 6, 7, 8 and 9.

Table 6
no experiencepHSilica SolThe particle size of ZolaMechanical properties after 1 h after applicationMechanical properties after 24 h after application
wet on wet abrasion resistanceThe pencil hardness scalewet on wet abrasion resistanceThe pencil hardness scale
10a9Ludox HS-4012 nm92B92B
11a9Nyacol16 nm52B52B
12A9Bindzil40/17020 nm52B52B
13A9Ludox TM-4022 nm7<2B7<2B

Table 7
no experiencepHSilica SolThe particle size of Zola Mechanical properties after 1 h after applicationMechanical properties after 24 h after application
wet on wet abrasion resistanceThe pencil hardness scalewet on wet abrasion resistanceThe pencil hardness scale
10b10Ludox HS-4012 nm40B≫1002H
11b10Nyacol16 nm35HB≫1003H
12b10Bindzil 40/17020 nm75H≫1003H
13b10Ludox TM-4022 nm6In60HB

Table 8
no experiencepHSilica SolThe particle size of ZolaMechanical properties after 1 h after applicationMechanical properties after 24 h after application
"wet-on-wet the mu abrasion The pencil hardness scalewet on wet abrasion resistanceThe pencil hardness scale
10c11Ludox HS-4012 nm>100HB≫1002H
11c11Nyacol16 nm55H≫1003H
12c11Bindzil 40/17020 nm30HB≫100HB
13c11Ludox TM-4022 nm15HB100H

10d
Table 9
no experiencepHSilica SolThe particle size of ZolaMechanical properties after 1 h after applicationMechanical properties after 24 h after application
wet on wet abrasion resistanceThe pencil hardness scalewet on wet abrasion resistanceThe pencil hardness scale
>11Ludox HS-4012 nm>1002H≫1004H
13d>11Ludox TM-4022 nm15HB60HB

From tables 6-9 becomes obvious that lowering the pH of the sols with an average particle size of from 12 to 20 nm affects (development characteristics) of the coating. On the other hand, the increase in pH of the Sol with a particle size of 22 nm increases the speed of development of the characteristics of the coating.

Example 14

Received the following samples primer:

Content (% wt.) in the liquid composition
ComponentA sample AndSampleSample
Ludox HS-4034,9535,0748,08
Water15,6315,6821,49
Bentone EW0,20,20,27
XZ 94770of 3.073,094,23
Zinc (powder)42,1542,290
Molywhite 2122,3300
Minex 201,67to 3.6725,93
the ratio of PVC/CPVC0,720,720,80

Sample And practically corresponds to a sample previously obtained in example 2, the description of the present invention. The sample does not contain additives Molywhite, and the sample contains no additives Molywhite 212 and powdered zinc.

The obtained primer coating was applied to a steel panel size 15 cm × 10 cm, and dry film thickness ranged from 15 to 20 μm, and was dried at 23°C and a relative humidity (RH) of 60%. The physical characteristics of the samples were measured after 1 hour, 2 hours and 24 hours after application. The test results shown in table 10.

Table 10
Mechanical properties (strength, wear wet on wet / pencil hardness scale)
Sample cover1 hour2 hours24 hours
And25/NR37/N>100/3H
In30/HB44/NV>100/2H
25/NR34/NV >100/2H

As can be seen from table 10, all three coatings have very similar properties. This shows that the additive Molywhite 212 and powdered zinc are not required to obtain coatings of the present invention, with the rapid development of the required physical characteristics of the coating after application.

1. Primer coating for coating a metal substrate, intended for the manufacture of products and the application of the top coating layer, with the specified primer coating contains silicate binder, wherein the ratio of the volume concentration to the critical pigment volume concentration of pigment in the specified primer coating is less than 1, the binder contains a water silicasol (Sol of silicon dioxide) and, optionally, a small amount of silicate of alkali metal, and particles of silicon dioxide have an average size greater than 10 nm in the binding molar ratio of SiO2/M2O is at least 25:1, where M stands for all ions such as alkali metal and ammonium in total.

2. Primer coating according to claim 1, characterized in that the volume concentration of the pigment is from 40 to 55%.

3. Primer coating according to claim 1, characterized in that the binder contains particles of colloidal silica, the average size of a cat is, which is from 10 to 22 nm.

4. Primer coating according to claim 3, characterized in that the binder contains particles of colloidal silica, an average size of from 10 to 16 nm.

5. Primer coating according to claim 4, characterized in that the pH of the water silicasol is from 9.5 to 11.

6. Primer coating according to claim 1, characterized in that the primer coating further comprises from 0 to 30 wt.% organic resin dry binder.

7. Primer coating according to claim 6, characterized in that the primer coating further comprises from 10 to 20 wt.% organic resin dry binder.

8. Primer coating according to claim 1, characterized in that the binder contains a water silicasol, surface modified aluminum oxide.

9. Primer coating according to claim 9, characterized in that the binder contains from 0.05 to 2.5 wt.% of aluminum oxide, calculated as a percentage (wt.) Al2O3per silicasol in composition.

10. Primer coating according to claim 1, characterized in that it is a primer coating is water-based.

11. Primer coating according to claim 1, characterized in that the coating further includes a powder of zinc and/or zinc alloy.

12. Primer coating water-based coatings on steel substrates intended DL is the manufacture of products and the application of the top coating layer, moreover, the solids content in the specified primer coating is from 20 to 40 vol.% and the ratio of the volume concentration to the critical pigment volume concentration of the pigment is less than 1, containing aqueous silica Sol as a binder with a molar ratio of SiO2/M2O at least 25:1 and a pH of from 9.5 to 11, where M stands for all ions such as alkali metal and ammonium in an amount and particles of silicon dioxide, optionally modified aluminum oxide, have an average size of from 10 to 16 nm, 10-55% powdered zinc and/or zinc alloy, calculated on the dry film with an average particle size of from 2 to 12 μm, 0-35 wt.% organic resin dry binder, 0-30 wt.% silicone sizing dry binder; optionally, the pigment(s), not containing(s) zinc; and optionally, a filler that increases the durability of the primer during storage.

13. The method of applying a primer coating to the steel substrate, which comprises the following stages: obtaining the primer coating according to any one of claims 1 to 12 using silicates, the pH of which was adjusted to 9.5-11, and applying this primer coating on the steel substrate.

14. The method of applying a primer coating to the steel substrate, which comprises the following stages: application of primer coating according to any one of claims 1 to 11 N. the steel substrate, optionally, the processing solution, a reinforcing film, after drying the primer coating to dry to the touch.

15. The method of applying a primer coating to the steel substrate, which comprises the following stages: application of primer coating according to any one of claims 1 to 11 on a steel substrate, the immersion coated with a primer coating of the substrate in water or, alternatively, keeping it in an atmosphere with a relative humidity of at least 50% after drying the primer coating to dry to the touch.



 

Same patents:

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