BRPI0707140B1 - Process and apparatus for spraying without pneumatic assistance without pneumatic assistance a surface with a viscous aqueous architectural coating composition - Google Patents

Abstract

a process and apparatus for spray-free coating of a surface with a viscous aqueous architectural coating composition, and a viscous aqueous architectural coating composition. Disclosed is a process, apparatus and coating composition for spray-free coating (e.g., airless) a surface with a viscous aqueous architectural coating composition (e.g., a paint) suitable for hiding marks on surfaces whose composition has a non-Newtonian flux and contains a binder polymer and above 30% by weight of solid ingredients (especially those chosen from thickeners, opacifiers, pigments and diluents) wherein the composition is expelled through a hole in a nozzle under a pressure of 2, 5 to 5 bar that can be generated by a hand or electric pump. a suitable composition has a brookfield viscosity of at least 0.5 pa and preferably not exceeding 50 pa if it contains a predominantly associative thickener for spraying through an oblate or circular orifice, or alternatively has an apparent extensional viscosity of 0.10%. 05 to 0.5 pa.s. preferably, the nozzle has devices for imparting a transverse force to the composition so that it enters the orifice with swirling motion.

Description

(54) Title: PROCESS AND APPLIANCE TO COVER BY ASPERSION WITHOUT PNEUMATIC ASSISTANCE WITHOUT PNEUMATIC ASSISTANCE A SURFACE WITH A COMPOSITION OF ARCITETONIC WATERPROOF COATING VISCOSA (51) Int.CI .: B05D 1/02; B05B 9/00 (30) Unionist Priority: 13/01/2006 GB 0600674.6, 17/03/2006 EP 06380052.8 (73) Holder (s): AKZO NOBEL COATINGS INTERNATIONAL B.V.

(72) Inventor (s): GERAD MARY SPILLANE; MIGUEL ANGEL IRIZAR IGARZABEL; ARKAITZ ZABALO ONDARRA

PROCESS AND APPARATUS TO SPRAY A SURFACE WITH ASPERSION WITHOUT PNEUMATIC ASSISTANCE WITH A COMPOSITION OF WATER ARCHITECTURAL COATING

VISCOSE

This invention relates to a process and apparatus for spraying without a pneumatic assistance a surface with a viscous aqueous architectural coating composition that is a suitable composition for hiding marks on surfaces, a process that can meet non-Newtonian flow using non-Newtonian pressures. more than 5 bar. In practice, spray coating without pneumatic assistance usually means that the spray formation is not assisted by air injection, but occasionally other gases, such as carbon dioxide, are used instead of air and so, to summarize, no air will be used in this description to denote spray coating in which the spray formation is not assisted by air or any other gas. The invention also relates to a coating composition for use in the process and apparatus.

The significance of pressures up to 5 bar is that these are pressures obtainable by simple hand-operated compressors, usually less precisely known as hand pumps. It is also possible to use an electric pump to generate such pressures.

Architectural cladding compositions are almost always paints and the like, to summarize, paints will often be used in this description to denote architectural cladding compositions in general. Most paints suitable for hiding marks have a non-Newtonian flow resulting from their pseudoplastic nature that causes them to undergo non-linear reductions in viscosity when subjected to high shear. Despite more than 70 years of painting by

Petition 870170089154, of 11/17/2017, p. 6/15 sprinkling (despite high pressures), there is still no simple or reliable way to predict how such non-linear viscosity reductions will affect the characteristics of the sprinklers obtained.

Architectural paints are designed for application on surfaces found in buildings, or parts of them, such as walls, ceilings, window frames, doors and door frames, radiators and custom furniture. Some paints are particularly designed for application on external building surfaces and on surfaces found in the earth (for example, gardens and patios) around buildings. Such surfaces are usually stone, brick or concrete, and it is hoped that the paints can reasonably hide marks on the surface. Paints must be applied on site at ambient temperatures and humidity, both by amateur and professional painters. Ambient temperatures in Europe encountered during on-site painting are typically 5 to 45 ° C. For paints to be reasonably suitable for hiding marks, they must contain sufficient opacifiers, pigments and / or thinners to give the paint a total solids content of at least 30% by weight (based on the total weight of the paint before drying) and preferably a solids content of 40 to 70% by weight, with 43 to 55% by weight being the most preferred range. Diluents are solid particles, for example, of clays and / or chalk, which are added to the architectural coating compositions in order to separate pigment and / or opacifying particles, whereby they increase their pigmentation and opacification efficiencies. A more complete description of them is given in the third edition of an Introduction to Paint Chemistry by G P A Tumer, published in 1967 by Chapman and Hall of London, whose contents are incorporated by reference here.

The application can be done by brush or roller, or, if the painters are professionals, by spraying (optionally assisted by air) generated using pressures above 130 bar. Spraying large areas is on the order of five to ten times faster than painting with a brush, but the high pressure device used is both very expensive and very dangerous for use by amateurs, that is, painters on their own. .

Cheap low pressure sprinkler that can be pressurized to about 3 bar using a hand pump is widely used by hobbyists (especially gardeners) to spray organic solvent-based liquids, such as wood paints, fungicides and insecticides, which contain low or zero levels of solid material, and which have negligible Brookfield viscosities, which means that they have Newtonian flow which makes them easy to spray. Attempts to use such a device to spray aqueous paints with a Brookfield viscosity at 22 ° C above 0.5 Pa.s and solids contents above 7% by weight have resulted in the production of approximately cylindrical jets of small radii, which collide in a no more than tiny and approximately circular area of a target surface. The small size of this area would take the painting process a long time.

The Cuprinol brochure introducing a major breakthrough in Fence Treatments for 2005 published in 2005 describes commercially available devices for spraying non-Newtonian architectural coating compositions using pressures up to 5 bar generated by a hand pump. The architectural coating composition is contained in a reservoir that is pressurized by the pump to distribute the composition through a nozzle to an elongated crack formed in the nozzle, from which the composition comes out as a flat fan-shaped sprinkler. However, it has been found that the device can only be used successfully with architectural coating compositions with solids content below about 12% by weight that, otherwise, the architectural coating composition cannot both emerge from the crack or not. emerges as a spray or usable jet. A possible reason for inefficiency when the solids content is high is that a large part of the energy in the ink flow entering the nozzle is consumed in the flow shear adjacent to the slit walls and causing the solid particles in the ink to rotate. Before explaining how this problem can be overcome, it would be useful to describe a little about the formulation of aqueous architectural paints and the way in which they acquire their viscosity.

Aqueous architectural paints typically comprise an aqueous organic film-forming binder latex that serves first to bond a dry coating of the composition to a surface on which it has been applied and, second, to bond any other ingredients of the composition, such as pigments, dyes, opacifiers, thinners and biocides in the dry coating. The binding polymer is a significant cause of non-Newtonian flow.

A wide variety of conventional film-forming binder polymers are available for use in aqueous architectural paints, but the most commonly used are of three general types obtained from ethylenically unsaturated monomers, and they are colloquially known as acrylic, vinyl or styrenic. Acrylics are typically copolymers of at least two alkyl esters of monoethylene unsaturated carboxylic acids (e.g., methyl, ethyl, butyl or 2-ethylhexyl esters of acrylic or methacrylic acids, such as methyl methacrylate / butyl acrylate copolymer) optionally with some non-esterified acid (for example, acrylic or methacrylic acid). Vinyls typically comprise copolymers of a vinyl monoester of a saturated carboxylic acid, such as vinyl acetate and at least somewhat of an acrylic monomer and of a different vinyl monoester, for example, the vinyl ester of a carboxylic acid containing 10 to 12 carbon atoms, such as those sold under the trade name of Versatate by Resolution Europe BV of Rotterdam. Styrenics are copolymers containing styrene (or a similar mono-vinyl aromatic monomer) together with a copolymerizable monomer that is normally an alkyl ester of acrylic or methacrylic acid. A more complete description of suitable aqueous binder polymers is given in Tumer, ibid.

Architectural paints need to have a low-shear viscosity (ie a Brookfield viscosity at 22 ° C) of at least 0.5 Pa.s (Pascal.second) so that if they were applied to a vertical surface at a thickness conventional in the range of 0.02 to 0.05 mm, the applied coating will generally resist dripping, that is, dripping on the surface below before the coating has time to dry enough to lose its fluidity. Drainage is illustrated in Plate 14 of the Handbook of Painting and Decorating Products by A H Beckly published in 1983 by Granada of London, whose contents of Plate 14 are incorporated by reference here. In aqueous paints, most of the viscosity is usually conferred by the inclusion of cellulosic thickeners of long or medium chain lengths, and these greatly contribute to non-Newtonian flow. A more complete description of thickeners suitable for use in architectural coating compositions is given by E J Schaller and P R Sperry in Chapter 4 of Volume 2 of The handbook of Coatings Additives edited by L J Caibo, the contents of which in Chapter 2 are incorporated by reference.

Shaller and Sperry explain that there is a need for thickeners in aqueous latex paints to adjust viscosity in order to control various properties of the paints, including runoff and also film formation and leveling. They list the various ways in which viscosity can be increased, but conclude that thickeners (which they alternatively call water-soluble polymers) provide a more efficient and controllable means of adjusting viscosity. Shaller and Sperry continue to differentiate between two types of thickeners known as non-associative thickeners and associative thickeners. Non-associative thickeners are water-soluble (or at least water-swellable) polymers that increase viscosity basically by overlapping and / or entangling their polymer chains and / or by occupying large volumes of space within the paint. These effects are promoted by the molecular weight, rigidity and straightness of their polymer chains. Associative thickeners are also water-soluble (or at least water-swellable) polymers. They have hydrophobic groups chemically attached that are capable of self-association in micellar-type assemblies, as well as are capable of non-specific adsorption on all colloidal surfaces present. This behavior is analogous to that of conventional surfactants. This results in a transient network of polymer chains that increase the Brookfield viscosity of paints.

The most important non-associative thickeners are long, medium or small chain cellulose ethers, known as cellulosics, which comprise straight and rigid polymeric backbones, which make cellulosics exceptionally effective in increasing the viscosity of aqueous systems. The chain length is defined in terms of average molecular weight by weight derived from viscosity measurements. Examples of cellulosics include hydroxyethyl cellulose, sodium carboxymethyl cellulose, methyl cellulose, hydroxyproylmethyl cellulose and ethyl hydroxyethyl cellulose.

Long-chain cellulosics (for example, molecular weights above 250,000 Da) and medium-chain (for example, 100,000 to 250,000 Da) increase viscosity by entangling the chain that allows high Brookfield viscosities to be achieved at low concentrations. However, if the concentrations of long and medium chain cellulosics are to be increased to achieve high viscosities at high shear (which is necessary for high film build-up), they will inhibit the atomization of the coating composition during spraying, resulting in accumulation of excessive and uneven film and runny.

Short-chain cellulosics (eg, molecular weights below 100,000 Da) increase viscosity primarily due to concentration effects (eg, volume occupancy) and they are less likely to inhibit atomization during spraying. However, high concentrations are necessary to achieve the required Brookfield viscosities. Such high concentrations are expensive to use and, moreover, they significantly impair the water resistance of the dry coating, making it vulnerable to rain or water condensation.

Associative thickeners are relatively low molecular weight and they overcome some of the drawbacks of cellulosics. The transient networks they create produce increases in Brookfield viscosity comparable to those obtained with high molecular weight cellulosics. This allows them to be used in relatively small concentrations that do not seriously impair the water resistance of the dry coating.

Schaller and Sperry report that four main types of associative thickeners have found commercial use in aqueous coating compositions. The first, main type is the hydrophobically modified alkali-soluble emulsion type, or HASE. Commercial examples of HASE types have hydrophilic backbones comprising salts of polymerized or copolymerized unsaturated carboxylic acids or acid anhydrides, such as acrylic or methacrylic acid, or maleic anhydride. Hydrophilic fractions such as polyalkylene glycols (for example, polyethylene glycol) are attached to the hydrophilic backbones and hydrophobic groups are in turn attached to the hydrophilic fractions. In use, solutions of these HASE thickeners are added as flowable liquids to a coating composition at neutral or slightly acidic pH. An increase in Brookfield viscosity is then caused by an increase in pH to slightly alkaline conditions (say, 8 to 9), by which carboxylate anions are formed.

The second type of associative thickener is the hydrophobically modified alkyl hydroxy cellulose type (especially ethyl), or

HMHEC conveniently made by adding long chain alkyl epoxides to hydroxyalkyl celluloses of the type used as non-associative thickeners.

The third type of associative thickener is the HEUR block / condensation copolymer type comprising hydrophilic blocks and hydrophobic blocks normally ending in hydrophobic groups. Hydrophilic blocks can be provided by relatively low molecular weight polyalkylene oxide (especially polyethylene oxide) fractions, say below 10,000 Da, preferably 3,400 to 8,000 Da. Hydrophilic blocks are condensed, for example, with urethane-forming diisocyanates hydrophobic such as toluene diisocyanate.

The fourth type of associative thickener is the hydrophobically modified polyacrylamide type in which the hydrophobic groups are incorporated as free radical copolymers with N-alkyl acrylamides. These are most commonly used in acid coating compositions.

A fifth major type of associative thickener has been introduced since Shaller and Sperry's review. This is the type of hydrophobically modified ethoxylated urethane oxide intumescible emulsion or 'HEURASE'. This type combines the functionality of the HASE and HEUR types.

It has recently been found that where a non-Newtonian architectural coating composition has a high solids content and derives significant amounts of its thickener viscosity, however there are conditions that allow spraying without pneumatic assistance of the composition, even when the composition is sprayed using cheap sprinkler device that operates at low enough pressures to be easily generated using a simple and inexpensive hand pump, these being hand pumps that can be both made available and used safely by an amateur.

In this way, this invention provides a process for spray coating without pneumatic assistance (for example, without air) of a surface with a viscous aqueous architectural coating composition (for example, paint) suitable for hiding marks on surfaces, the composition of which presents non-Newtonian flow and contains a binding polymer and other solid ingredients (especially those chosen from thickeners, opacifiers, pigments and thinners) and whose process comprises expelling the composition under pressure through a hole formed in a nozzle, in which:

a) the solids content of the composition is at least 30% by weight (preferably 35 to 65% by weight and more preferably 40 to 53% by weight) of the total weight of the composition,

b) the composition has a Brookfield viscosity measured at 22 ° C of at least 0.5 Pa.s and preferably not exceeding 50 Pa.s and more preferably a Brookfield viscosity of 1 to 12 Pa.s,

c) the composition contains from 0.08 to 0.6% by weight based on the total weight of the thickener composition, where more than 50% by weight (based on the total weight of thickener) is associative thickener,

d) the orifice has both an oblate circumference and, preferably, a circular circumference; and

e) the composition is subjected to a pressure of 2.5 to 5 bar before being expelled through the orifice.

It was observed that the thickening in the aforementioned amounts of predominantly associative thickener gives the composition an apparent extensional viscosity that allows effective spraying, even at pressures no higher than those that can reasonably be generated by a hand pump, especially if the orifice is elliptical and preferably circular . An oblate is understood as a hole that has a curved circumference (including an elliptical circumference), where the circumference has a larger diameter and also smaller diameters, but where the smaller diameter is not less than half the length (and preferably not less than at least four-fifths of the length) of the largest diameter. Preferably, the composition should not contain more than 0.4% by weight of thickener in order to minimize any risk of loss of yield strength. Preferably, the thickener should comprise 60 to 80% by weight (based on the total weight of the thickener) of associative thickener, with balance being r

non associative thickener. It is possible, but expensive, to have over 80% by weight and up to 100% by weight of associative thickener. The most preferred concentrations of associative thickener are 0.1 to 0.3% by weight based on the total weight of the composition.

The invention alternatively provides a process for spray coating without pneumatic assistance (for example, airless) of a surface with a viscous aqueous architectural coating composition (for example, paint) suitable for hiding marks on surfaces, the composition of which shows non-flow Newtonian and contains a polymer binder and other solid ingredients (especially those chosen from thickeners, opacifiers, pigments and thinners) and whose process comprises expelling the composition under pressure through a hole formed in a nozzle, in which:

a) the solids content of the composition is at least 30% by weight (preferably 35 to 65% by weight and more preferably 40 to 53% by weight) based on the total weight of the composition,

b) the composition has an apparent extensional viscosity measured at 25 ° C from 0.05 to 0.5 Pa.s (and preferably from 0.15 to 0.35 Pa.s) together with a Brookfield viscosity measured at 22 ° C of at least 0.5 Pa.se preferably not exceeding 50 Pa.se more preferably a Brookfield viscosity of 1 to 12 Pa.s, and

c) the composition is subjected to a pressure of 2.5 to 5 bar before being expelled through the orifice.

It was observed that the selection of compositions with the mentioned range of apparent extension viscosities allows effective spraying, even at pressures that can reasonably be generated by a hand pump, especially if the orifice is oblate or, preferably, circular.

For the purposes of this description, the apparent extensional viscosity, q _a , of a complex non-Newtonian fluid, such as an aqueous architectural coating composition, is defined as:

fia = ã §t where σ is the surface tension of the coating composition at 25 ° C and ôd / δΐ is the rate of decrease in time, t, in diameter, d, of a vertical capillary filament of the composition at its point medium, whose capillarity is formed when the composition is placed between two vertically opposing plates, and the plates are quickly separated according to the procedure described in the Haake CaBER 1 Instruction Manual, available from Thermo Haake (International) of Karlsruhe, Germany. The contents of the Haake CaBER 1 Instruction Manual are hereby incorporated by reference. The midpoint is the equidistant point of the plates. CaBER stands for Capillary Break-up Extensional Rheometer.

The procedure used for the purposes of this description involves placing the paint between two 6 mm diameter vertically opposed plates with an initial separation of 3 mm. The plates are then pushed vertically away from each other very quickly for a period of 50 ms until a separation of 7 to 20 mm in order to create the capillary filament of liquid that connects the two plates. As a result of surface tension and gravity drainage, the filament thins and eventually splits into two separate droplets, one attached to the upper plate and the other to the lower plate. A laser micrometer is used to make a sufficient number of sequential measurements of the filament's midpoint diameter as it tapers for the purpose of determining ôd / ôt. Measurements are preferably made at a frequency of 1 to 30 kHz for a period of time of 0.1 to 1 second, with the precise frequency and period for a particular composition being chosen by trial and error, ensuring that measurements are made enough of the midpoint diameter, etc. Diameters above 700 pm are preferably ignored to minimize initial distortions because of gravity and, at least when this is done, the graph comprises a substantially linear part. The gradient of this part is considered ôd / ôt. Care is needed to move the plates at a constant speed during their separation and, in particular, there should be no damping because of any final deceleration.

The final distance between the plates is chosen so as to produce a capillary filament whose useful life is long enough to allow a sufficient number of valid measurements to be made for the purpose of determining ôd / ôt. For example, a final separation of about 20 mm (say 19.8 mm) is preferred for Brookfield high viscosity compositions, while a final separation of 14 to 15 mm (say 14.5 mm) is preferred for Brookfield viscosities. intermediate, and a final separation of about 8 mm (say 7.9 mm) is preferred for low Brookfield viscosities.

A refinement of the procedure is preferred to determine ôd / ôt for non-Newtonian compositions. It comprises making an determination of Ôd / Ôt in the manner described above, then quickly returning the plates to their starting positions and then repeating the determination as soon as possible after the plates have resumed to the starting position. Sufficient time (usually 0.1 to 30 seconds, depending on the particular composition) has to be given for the composition to recover enough structure to be able to form a filament again. Then more repeated determinations similar enough to ôd / ôt are made to allow the reliable construction of an ôd / ôt graph over time. It was found that the graph produces an asymptotic ôd / ôt value that is most used in predicting the spray characteristics of the composition.

If the apparent extensional viscosity exceeds 0.5 Pa.s, then the architectural coating composition is expelled at most as a jet or stream of large droplets, which produces an excessively thick coating that runs or runs quickly downward on a vertical surface and , in the worst case (for example, if the apparent extensional viscosity exceeds about 2 Pa.s), the composition cannot be expelled in any way. If the apparent extensional viscosity falls below 0.05 Pa.s, the architectural coating composition will be expelled as a fine mist that does not coat the vertical surface efficiently, and that is vulnerable to inhalation by an unprotected (usually amateur) painter or when being blown outdoors with breeze.

For coating without efficient draining, it is preferable that 50% by volume of the sprayed paint is sprayed as droplets with a diameter in the range of 150 to 300 pm (and more preferably 180 to 250 pm). Preferably, no more than 5 to 20% (preferably 8 to 15%) by volume of the sprayed paint are sprayed as droplets with a diameter below 100 pm, otherwise there will be an undesired danger of the jet being inhaled or blown by the wind. It is also preferable that no more than 5 to 20% (preferably 8 to 15%) by volume of the sprayed paint are sprayed as droplets with a diameter above 300 pm.

As a preferred but not sufficient condition to achieve the appropriate apparent extensional viscosity, it is preferable that the high shear viscosity of the paint at 25 ° C is reduced to 0.015 to 1.0 Pa.s (preferably, 0.02 to 0 , 12 Pa.s), when under high shear upstream of the orifice, where high shear means a shear speed of 104 / s. Viscosity at such shear rates can be measured by the ICI Cone and Plate viscometer, described in the ASTM Test D4827-88.

Other factors that can affect the usefulness of sprinkles are certainly the surface tension of the paint and its density. Both are functions of the complex formulations used to make modern paints, so it is not easy to vary both. In theory, the surface tension (and, consequently, apparent extensional viscosity) can be reduced by adding detergents to an ink, but this will increase the ink's sensitivity to water. Consequently, variation in surface tension is generally a practical option. Most architectural paints will have a surface tension at 20 ° C in the range of 20 to 60 (preferably 23 to 45) N.10 ' ³ / m.

The density of paints is strongly affected by their concentrations of heavy inorganic opacifiers, such as titanium dioxide, rutile (which also serves as a white pigment), or colored pigments or thinners, such as calcium or magnesium carbonates, or clays. The concentrations of pigment and thinner are carefully chosen to give colors with precise hues, chroma and gloss, thus varying their concentrations merely to adjust the density is also rarely a practical option. In short, the density cannot vary significantly without unacceptable consequences for opacity and color, and the eye is very sensitive to color variations. Generally, the density of an aqueous paint is 1.1 to 1.6 kg / liter for compositions with solids content above 30% by weight.

In carrying out this invention, ink is provided in a reservoir that can be pressurized by the hand-held compressor in order to pump ink through a hose through a nozzle to an outlet orifice formed in the nozzle, from which the ink is sprayed. The circumference of the orifice is preferably circular, but it can be oblate. Preferably, the hole has a diameter greater than 0.5 to 2 (preferably 0.7 to 1.3 mm) and an axial length preferably 0.2 to 1 mm and more preferably 0.3 to 0.7 mm .

It is also preferable to give a transverse force to the ink as it passes through the nozzle, in order to rotate the ink flow, causing it to pass through the hole with an essentially helical whirl movement that increases the shear forces of the ink which, in turn, it is believed to assist in atomizing the flow in a sprinkling of duly sized droplets. Transverse is understood to be an angle with another general direction of displacement of the composition from its entry into the nozzle to its exit through the orifice.

The transverse force can be conferred, for example, by reacting an inclined surface at an angle (preferably 25 ° to 65 °) with the general direction of flow of the coating composition through the nozzle, that is, inclined with the longitudinal axis of the nozzle. Suitable surfaces can be provided by one or more helical faces (similar to the internal radius of the barrel of a revolver) located in an elongated portion of the nozzle, which portion extends upstream. However, the preferred means of providing a suitable reaction comprises an annular ring in which a plurality (preferably 3 or 4) of substantially tangential notches (i.e., at least partially) extending from the outer circumference of the annular crown to its internal circumference. The notches are preferably 0.5 to 1.5 mm wide and the inner and outer radii of the annular crown are preferably 4 to 6 mm and 5 to 7 mm, respectively, provided that the outer radius is certainly greater than the inner radius. The notched annular corrode is preferably made integral with the nozzle, whereby the nozzle and annular crown form part of the same unitary component, and the unitary component does not rotate so that the transverse force comes from the surface without assistance from any coupling of fluid. Preferably, the notched annular crown receives ink from the pressurized reservoir by means of partial annular clearances formed on a disc upstream of the notches, the clearances of which communicate with the outer ends of the notches.

When leaving the orifice, the jet expands to define a conical shape as it moves towards the surface to be coated, thus allowing the coating of a wider band. The maximum preferred cone diameter is 100 to 250 mm at a distance of 100 to 150 mm from the orifice in order to minimize the risk of the cone becoming uneven, leading to a less uniform surface coating.

It is also preferable to pass the ink flow through a filter as it travels from the reservoir to the nozzle, in order to shear and break any agglomerate of pigments or thinners that may be present in the ink. A preferred filter comprises a mesh with rectangular openings whose sides are 0.8 to 1.5 mm long. Ink is preferably distributed from the reservoir to the nozzle by means of a tandem combination of a flexible hose and a rigid lance that incorporates a firing mechanism to stop and start the ink distribution. The various components of the dispensing device all impart a certain shear to the paint as it passes through them, and the shear will affect the viscosity of the paint and thus have to be taken into account in the design of the total spraying apparatus.

The nozzle geometry should be selected with the composition distribution rate in mind. It has been observed that the paint compositions are better distributed at a rate of 0.3 to 1.3 liters / minute, and preferably 0.5 to 1 liter / minute. The spray stability can be affected by the ambient temperature which can increase or decrease the apparent extensional viscosity of the composition. A distribution rate of 0.6 to 0.9 L / minute is believed to be least affected by changes in temperature.

Selecting ideal nozzle dimensions is a simple matter. It is suggested that, to start, the nozzle dimensions should be chosen to be about half of the preferred ranges and then the dimensions may vary possibly with variations in the pressure of the hand pump in order to investigate how the flow rates and distribution rates vary with pressure for any particular ink.

The distribution of the composition by means of a pressure chamber (preferably cylindrical) upstream of an outlet port, and leading to it, can optionally be used to minimize fluctuations in pressure, which can accompany the operation of the hand pump by an amateur, who can get tired with the continuity of pumping. Preferably, the pressure chamber should have a cross-flow dimension through the nozzle of 0.5 to 3 (especially 1.3 to 2.7) mm and a length of 0.2 to 4 mm (especially 0.2 to 3 mm ).

This invention also provides an apparatus for spray coating without pneumatic assistance a surface with a viscous aqueous architectural coating composition to hide marks on surfaces, the composition of which has non-Newtonian flow and in which the apparatus comprises.

a) a pressurized reservoir containing an architectural coating composition (for example, paint) with a solids content of at least 30% by weight (preferably 35 to 65% by weight, and more preferably 40 to 53% by weight) based in the total weight of the composition, and including from 0.08 to 0.6 (preferably 0.1 to 0.4) in weight (based on the total weight of the composition) of thickener, where more than 50% by weight (preferably , at least 60% by weight, and more preferably at least 80% by weight) of the thickener (based on the total weight of thickener) are associative thickener, and the composition has a Brookfield viscosity of at least 0.5 Pa.se preferably not exceeding 50 Pa.s, and above all preferably a Brookfield viscosity of 1 to 12 Pa.s, and

b) a nozzle in communication with the reservoir, the nozzle of which ends in an oblate or circular outlet port,

c) a compressor capable of pressurizing the composition from 2.5 to bar, and

d) a pressure release valve adjust to release pressure from the container when the pressure reaches a value in the range of 2.5 to 5.0 bar.

This invention provides at least apparatus for spray coating without pneumatic assistance (for example, without air) a surface with a viscous aqueous architectural coating composition suitable for hiding marks on surfaces, the composition of which has non-Newtonian flow and in which the apparatus comprises:

a) a pressurizable reservoir containing an architectural coating composition (for example, paint) with a solids content of at least 30% by weight (preferably 35 to 65% by weight, and more preferably 40 to 53% by weight) based the total weight of the composition, and the composition has an apparent extensional viscosity, measured at 25 ° C, from 0.05 to 0.5 Pa.S and a Brookfield viscosity of at least 0.5 Pa.s,

b) a nozzle in communication with the reservoir, the nozzle of which ends in an outlet orifice,

c) a compressor capable of pressurizing the composition from 2.5 to bar, and

d) a pressure release valve adjusted to release pressure from the container when the pressure reaches a value in the range of 2.5 to 5.0 bar.

Although both devices mentioned can use hand pumps, either can use pressures generated by the domestic low pressure compressor, if they can create pressures of 2.5 to 5 bar. Similarly, electric pumps can be used to generate pressures, if appropriate.

This invention additionally provides a viscous aqueous architectural coating composition that has a non-Newtonian flow and is suitable for spraying on a surface at a pressure of 2.5 to 5 bar to hide marks on it, the composition of which has a content of hair solids minus 30% by weight (preferably 35 to 65% by weight and more preferably 40 to 53% by weight) based on the total weight of the composition, and including from 0.08 to 0.6 (preferably 0.1 to 0, 4) by weight (based on the total weight of the composition) of thickener, where more than 50% by weight (preferably at least 60% by weight and more preferably at least 80% by weight) of the thickener (based on the total weight of the thickener) are associative thickener, and the composition has a Brookfield viscosity of at least 0.5 Pa.s and preferably not more than 50 Pa.s, and more preferably a Brookfield viscosity of 1 to 12 Pa.s. This invention alternatively provides a viscous aqueous architectural coating composition that has non-Newtonian flow and is suitable for spraying on a surface at a pressure of 2.5 bar to hide marks on it, whose composition contains a binder polymer and other solid ingredients in which the composition has a solids content of at least 30% by weight (preferably 35 to 65% by weight, and more preferably 40 to 53% by weight) based on the total weight of the composition, and the composition has an apparent extensional viscosity, measured at 25 components from 0.05 to 0.5 Pa.and a Brookfield viscosity of at least

0.5 Pa.s and preferably not more than 50 Pa.s, more preferably a Brookfield viscosity of 1 to 12 Pa.s.

Brookfield Viscosity Measurement:

Brookfield viscosity was measured at 22 ° C using a Brookfield Viscometer, Model HA, supplied by Brookfield Engineering Laboratories Incorporated of Middleboro, Massachusetts. Essentially, a Brookfield viscosity comprises a rotating tree that carries a disk which, when mediation is carried out, is immersed in the coating composition about 10 mm below its surface. The composition must be provided in a cylindrical container with a diameter of at least 100 mm in order to avoid errors due to the proximity of the reservoir walls.

To perform the measurement for the purposes of this description, a Brookfield tree no. 3, immersed in the composition and then rotates at Brookfield speed no. 10 for at least three revolutions. The shaft is coupled to a torque measuring device that is calibrated to express torque in terms of the viscosity of the composition, both directly and after the operation of a Brookfield-specified multiplier.

Surface Tension Measurement

The surface tension was measured at 20 ° C using the De Nuoy method which employs a wire ring with a wire diameter of 0.44 mm and a ring diameter of 13 mm. To perform the method, the ring is positioned horizontally on the surface of the composition so that it is held by a meniscus. The ring is pulled vertically upward from the meniscus and the minimum force required to do this is measured using a spring torsion balance.

This invention and preferred embodiments of your device will now be illustrated with reference to the drawings, in which:

Figure 1 is an exploded perspective view showing components of a nozzle assembly for use in apparatus in accordance with this invention.

Figure 2 is a plan view of the cracked disc shown in Figure 1.

Figure 3 is a plan view of the notched ring shown in Figure 1.

Figure 4 is a diagrammatic representation of an apparatus that incorporates a nozzle according to this invention.

Figure 5 is an exploded perspective view showing components of an alternative nozzle assembly according to this invention.

Figure 6 is a perspective view of the alternative cracked disc shown in Figure 5.

Figure 7 is a section on line A-A of the alternate cracked disc shown in figure 5.

Figure 8 is a perspective view of the integral nozzle and the notched ring shown in Figure 5.

Figure 9 is a section on line B-B of the integral nozzle and ring shown in figure 5.

Figure 10 is an exploded perspective view showing the components of Figure 5 when viewed from opposite directions.

Figure 11 is a section of the components shown in Figures 5 and 10 assembled and ready for use.

Figure 1 shows an exploded view of components of a nozzle assembly for use in apparatus in accordance with this invention. The components include:

i) nozzle 5 with an outer ring 5c and containing cylindrical outlet orifice 1 with a circular circumference formed at the distal end 5 a of the protrusion 5b of the nozzle 5;

ii) notched ring 2 with upstream face 2a in which three essentially tangential grooves are formed symmetrically located 16, also shown in dashed lines in figure 3, and inclined 45 ⁰ with the longitudinal axis of the nozzle 5;

iii) cracked disc 3 with three partially circumferential slits 13 located symmetrically around the disc adjacent to the base of the circumferential flange 14, whose flange 14 protrudes downstream when in use and defines the space 15; and iv) filter 4 comprising wire mesh 12 and a gasket 4a.

In use, these components are kept together in mutual contact by the cooperating coupling components of the type shown by 31 and 32 in figure 11, so that the ring 2 is kept in the space 15 defined by the flange 14 of the disc 3 and the assembled combination of the disk 3 and ring 2 is held inside the nozzle 5 by the gasket 4a of the filter 4, which is pushed against the outer ring 5c of the nozzle 5 by coupling components of the type shown as 31 and 32.

To use the device, paint is poured into the 5 liter reservoir 7, shown in figure 4, and a pumping pressure of 2.5 to 5 bar is generated using a hand pump 8. In an alternative embodiment, the pressure can be generated using an electric pump. A flexible hose 9 goes from the reservoir 7 to a valve 10, which can be opened by means of a trigger 10a, so that, by opening the valve 10, paint 6 under pressure moves through the rigid lance 11 through the wire mesh 12 of the filter 4. The wire mesh 12 filters and shears the paint 6, which then leaves the filter 4, travels the elongated cylindrical part 5 d of the nozzle 5, meets the upstream face of the cracked disc 3 and then flows through the slits 13 to the notches 16 on the notched ring 2.

The notches 16 extend between the outer and inner circumferences 18 and 17 of the ring 2. As it passes through the notches 16, paint 6 (still under pressure) exerts a rotating force on the ring 2, causing it to rotate. Paint 6 then enters the space between the ring 2 and the outlet port 1, which is of the type defined by the inner surface 25d of the protruding portion 25b shown in figure 9. In this space, the coupling of viscous fluid between the paint 6 and the ring rotating 2 causes the ring 2 to exert a transverse force on the ink flow 6, which, together with the transverse component of the flow direction imposed on the ink by the tangential notches 6, causes and / or increases the rotation (ie swirling) moving ink 6.

A swirling stream of paint 6 enters outlet port 1 through which it travels with swirling motion (i.e. helical). It is then expelled through the orifice 1, whereby it is atomized and forms the paint cone 19 which can be directed and applied to the surface 20 in a coating process.

In an alternative embodiment, the cracked disc 3 and the rotating ring 2 are omitted and a helical movement is provided by the helical faces (not shown) similar to the internal radius of the barrel of a revolver which are provided in the part of the nozzle 5 d.

Figures 5 to 11 show a more preferred embodiment of a nozzle assembly for apparatus according to the invention. In particular, figure 5 shows the cylindrical circular hole 21 formed at the distal end 25 a (see figure 10) of the conical part 25b protruding from the nozzle 25. The nozzle 25 is integral with the notched annular crown 22 containing notches essentially tangential 26 that extend between the outer circumference 28 and the inner circumference 27 and inclined 45 ⁰ with the longitudinal axis of the nozzle 25. The cylindrical space 22a (see figure 9) defined by the inner circumference 27 communicates in register with the space 25c defined by the inner surface 25d of the conical part 25b.

Figure 5 also shows the cracked disc 23 containing four symmetrically placed slits that extend partially circumferentially 23a (better seen in figure 6) that are located adjacent to the base of circumferential flange 23b that protrudes downstream when in use . The flange 23b is dimensioned to make a tight fit in the annular recess 25e formed in the nozzle 25. Finally, figure 5 also shows a filter 24 with gaskets 24a and 24b and wire mesh 24c.

Figure 11 shows the components of figures 5 to 10 when held in their positions assembled by coupling components with cooperating screw threads 31 and 32. Component 32 also holds the lance 12 in hermetic fluid communication with the filter 24. The gasket 24b holds the disc 23 in place at the nozzle 25 upstream and adjacent to the notches 26 with the pendant flange 23b of the disc 23 in place in the recess 25e.

Again, to use the device, paint 6 is poured into the 5 liter reservoir 7 and a pumping pressure of 2.5 to 5 bar is generated using a hand pump 8. As in the previous embodiment, pressure can also be generated using a pump electrical. The pumping pressure serves to make the paint 6 pass through the device in the general direction of the nozzle inlet 25 to the outlet through the orifice 21, but, otherwise, it has no significant effect on the formation of the spray, so that the process is essentially without pneumatic assistance as would be the case with a spray with conventional air assistance.

The valve 10 is opened and ink 6 under pressure flows through the flexible hose 9 and the valve 10 through the rigid lance 11 directly to the mesh 24c of the filter 24 shown in figure 11. The elongated nozzle part 5d is omitted in this embodiment. The paint 6 is filtered and sheared by the mesh 24c, after which it meets the upstream face of the cracked disc 23. It then passes through slits that extend in a partially circumferential manner 23a in the essentially tangential notches 26 formed in the notched annular crown. 22 as a result of which a cross reaction is exerted on the ink flow 6 by the surface 26a. The transverse reaction gives a helical or swirling movement to the ink flow, with which it travels through spaces 22a and 25c in nozzle 25. The swirling ink is then expelled through the outlet port 21, allowing an atomized cone 19 of ink 6 is directed and applied to the surface 20 in a coating process.

Nozzle components can be made of metal or molded from a thermoplastic material such as polyacetal or polypropylene.

The invention is further illustrated by the following Examples of which Examples A and B are comparative.

EXAMPLE 1

A viscous aqueous non-Newtonian paint with a solids content of 46.6 and suitable for hiding marks on a surface was made by mixing the ingredients shown in table 1. The paint had an associative thickener and had a pH of 8 to 9. Its Brookfield viscosity, surface tension, apparent extensional viscosity and density all at 22 ° C are also shown in table 1. The paint also had an ICI Cone and Plate viscosity at 25 ° C of 0.06 Pa.s.

The ink was filled in the 5 liter reservoir of the device described with reference to figures 5 to 11. Using the hand pump, the ink was pressurized to 4 bar and then the valve was opened, allowing the ink to be propelled from the reservoir and distributed by the flexible hose 10 mm in diameter through a valve and the lance through the filter in the nozzle. A helically rotating flow of ink was expelled through the nozzle outlet. The paint atomized well to give a conical spray about 200 mm in diameter at a point 150 mm from the hole. The paint sprinkled on a surface and produced a uniform coating capable of hiding the usual type of marks found on the external walls of domestic buildings. More efficient results would be achieved if the spraying was done with an action in which the boom moves along a loop path consisting of a circular revolution combined with a lateral displacement necessary to make it cross the surface in a linear direction. .

COMPARATIVE EXAMPLES A and B

A conventional viscous aqueous non-Newtonian paint to hide marks on a surface when applied by a brush was made by mixing the ingredients shown in Example A in table 1. Also, a paint of the type promoted by the aforementioned brochure was made by mixing it if the ingredients shown in table 2. The surface stresses, apparent extension viscosities, Brookfield viscosities and paint densities are shown in table 1.

Both paints were in turn sprayed onto the surface, as was done for example 1. Conventional ink to hide marks (Example A) failed to be sprayed, while the fence paint atomized excessively to give a wide conical mist that would certainly it broke easily.

Table 1

Ingredients Example 1 Parts by weight Example A Parts by weight Example B see table 2 Water 32.63 25.43 Mineral oil antifoam agent 0.31 0.45 Maleic anhydride pigment dispersant / olefin copolymer 1.08 1.00 Biocides 0.67 0.80 Benzilic alcohol 0.9 1.00 Anionic surfactant 0.18 0.20 Dolomite 3.9 3.00 Calcined clay 9.00 9.00 China clay 4.90 5.27 Titanium dioxide - Rutile 10.81 10.55 Medium chain-length hydroxyethyl cellulose: non-associative thickener 0 0.54 short chain length hydrophobically modified hydroxyethyl cellulose: associative thickener 0.18 0 Binding polymer * 32.42 34.20 Ammonia 0.11 0.12

Polymeric pigment with Ropaque voids 2.69 7.60 Acrysol TT615 0.20 0 properties % by weight of solids 46.56 48.65 10.1 Surface tension 10 ' ³ N / m 39.9 40.6 40 Brookfield Viscosity Pa.s 4.6 16 0.06 Apparent extensional viscosity Pa.s *** 0.3 3 0.025 End plate separation mm 7.9 19.8 7.9 Density kg / L 1.24 1.27 1.03

* The binder polymer is an aqueous latex of a copolymer of 51% by weight of methyl methacrylate, 48% by weight of e-2ethyl hexylacrylate and 1% by weight of acrylic acid.

** Acrysol TT-615 is an alkali-swellable acrylic polymer supplied 5 as an associative thickener by Rohm and Haas Company of

Philadelphia.

*** Determined by the refined method using its asymptotic value.

Table 2

Ingredient % by weight Water 88.7 Vinyl acetate copolymer / Versate vinyl 4.4 Acrysol TT-615 associative thickener 0.5 Pigments 2.9 Wax emulsion 2.3 Biocides 0.5 Coalescent, ammonia and defoamer solvent 0.7 Total solids content 10.1

Claims (23)

1. PROCESS TO COVER WITH ASPERSION WITHOUT PNEUMATIC ASSISTANCE A SURFACE WITH A COMPOSITION OF WATER ARCHITECTURAL COATING 5 VISCOSE, suitable for concealing marks on surfaces, whose composition has a non-Newtonian flow and contains a binder polymer and other solid ingredients, characterized by comprising expelling the composition under pressure through a hole formed in a nozzle (5), in which: a) the solids content of the composition is at least 30% by weight 10 of the total weight of the composition; b) the composition has a Brookfield viscosity, measured at 22 ° C, of at least 0.5 Pa.s .; c) the composition contains from 0.08 to 0.6% by weight based on the total weight of the thickener composition, where more than 50% by weight (with 15 based on the total weight of thickener) are associative thickener; d) coating composition has an apparent extensional viscosity, measured at 25 ° C, from 0.05 to 0.5 Pa.s; e) the orifice has both an oblate and a circular circumference; F) a transverse force is given to the composition as it passes through the nozzle (5), and g) the composition is subjected to a pressure of 2.5 to 5 bar before being expelled through the orifice. PROCESS, according to claim 1 characterized in that the coating composition contains from 0.08 to 0.6% by weight (based on the total weight of the composition) of thickener, where at least 60% by weight of the thickener ( based on the total weight of the thickener) is an associative thickener. Petition 870180036903, of 05/04/2018, p. 5/12 PROCESS according to claim 1 or 2, characterized in that the coating composition has a solids content of 40 to 53% by weight. 4. PROCESS according to any one of the claims 1 to 3, characterized in that the coating composition has a Brookfield viscosity, when measured at 22 ° C, from 1 to 12 Pa.s. PROCESS according to any one of claims 1 to 4, characterized in that the coating composition has an ICI Cone & Plate viscosity, when measured at 25 ° C, from 0.015 to 1.0 Pa.s. 10 PROCESS according to any one of claims 1 to 5, characterized in that a transverse force is given to the composition as it passes through the nozzle (5). 7. PROCESS, according to claim 6, characterized in that the surface is inclined at an angle of 25 ° to 65 ° with the 15 longitudinal axis of the nozzle (5). PROCESS, according to claim 6 or claim 7, characterized in that the surface confers the reaction as part of a notch (16) through which the coating composition passes. 9. PROCESS, according to any one of the claims 6 to 8, characterized in that the coating composition is fed into the surface that confers the reaction through at least one partially circumferential slit (13) upstream and adjacent to the surface. 10. PROCESS, according to any one of claims 6 to 9, characterized by the surface that confers the reaction to be 25 provided by at least one helical base provided in a circumferential portion of the nozzle (5). PROCESS according to any one of claims 6 to 10, characterized in that the coating composition passes Petition 870180036903, of 05/04/2018, p. 6/12 through a conical space located between the surface that confers the reaction and the orifice. 12. PROCESS according to any one of claims 1 to 11, characterized by 50% by volume of the sprayed paint 5 are sprayed as droplets with a diameter in the range of 150 to 300 pm. 13. PROCESS according to any one of claims 1 to 12, characterized in that the coating composition passes through a filter (4). 14. PROCESS according to any one of the claims 1 to 13, characterized in that the coating composition is distributed through the orifice at a rate of 0.3 to 1.3 liters / minute. 15. PROCESS according to any one of claims 1 to 14, characterized in that the compressor is a hand pump or in which the pump is electrically operated. 15 16. APPLIANCE TO COAT BY SPRAYING WITHOUT PNEUMATIC ASSISTANCE A SURFACE WITH A COMPOSITION OF ARCHITECTURAL ARCENTETONIC COATING VISCOUS, suitable for concealing marks on surfaces, whose composition has a non-Newtonian flow, using a process, as defined 20 in any one of claims 1 to 15, characterized in that it comprises: a) a pressurizable reservoir (7) containing an architectural coating composition that has a solids content of at least 30% by weight based on the total weight of the composition and that includes 0.08 to 0.6 by weight (based on in the total weight of the composition) of thickener, where more than 25 50% by weight of the thickener (based on the total weight of the thickener) is associative thickener, and the composition has a Brookfield viscosity of at least 0.5 Pa.s .; b) a nozzle (5) in communication with the reservoir (7), whose Petition 870180036903, of 05/04/2018, p. 7/12 nozzle (5) ends in an outlet orifice (1) oblate or circular; c) devices for imparting a force transverse to the longitudinal axis of the nozzle (5), which force causes the composition to enter the orifice with a swirling motion; D) a compressor capable of pressurizing the composition from 2.5 to 5 bar; and e) a set of pressure relief valve (10) to release pressure from the container when the pressure reaches a value in the range of 2.5 to 5.0 bar. 17. Apparatus according to claim 156 characterized by a pressurizable reservoir (7) containing an architectural coating composition that has a solids content of at least 35 65% by weight, preferably 40 to 53% by weight based on weight total composition. 18. APPLIANCE according to one of claims 16 or 17, characterized by the coating composition contains 0.08 to 0.6% by weight (based on the total weight of the composition) of thickener, where at least 60% by weight of the thickener (based on the total weight of the thickener) is an associative thickener. 19. Apparatus according to any one of claims 16 to 18, characterized in that the circumference of the hole has a diameter greater than 0.5 to 2 mm. 20. APPLIANCE according to any one of claims 16 to 19, characterized by the device for imparting a force 25 transversal to the composition comprises an inclined surface with the longitudinal axis of the nozzle (5). 21. Apparatus according to claim 20, wherein the surface is inclined at an angle of 25 ^o to 65 ^o. Petition 870180036903, of 05/04/2018, p. 12/8 22. APPLIANCE according to any one of claims 16 to 21, characterized in that it comprises a component upstream and adjacent to the surface for imparting the transverse flow, the component of which comprises at least a partially circumferential slit (13) through which the composition can be fed on the surface. 23. APPLIANCE according to any one of claims 16 to 21, characterized in that the device for imparting a transversal force to the composition is provided by at least one helical base located in a cylindrical portion (5d) of the nozzle (5). 24. APPARATUS, according to any one of claims 16 to 23, characterized in that the apparatus comprises a truncated cone space located between the surface that confers the transverse force and the orifice. 25. APPLIANCE according to any one of claims 16 to 24, characterized in that the compressor is a hand pump (8) or in which the compressor is an electrically operated pump. Petition 870180036903, of 05/04/2018, p. 9/12 1/7