SE409322B - PROCEDURE AND APPARATUS FOR APPLYING A COATING ON A SURFACE OF A SUBSTRATE - Google Patents

Description

15 20 25 50 _55 40 7316813-0 the country of techniques for applying vaporized coating compositions to heated substrates at atmospheric pressure, some difficulties have arisen. It has been difficult to obtain coatings which comprise fine grains and have a uniform appearance. Thick coatings have been prepared by contacting the substrate with a jet of liquid material, but it has been extremely difficult, if not impossible, to obtain fairly thick films having light transmittance of less than 50 percent using known vapor deposition techniques.

Methods for vapor phase precipitation are previously known. The most commercial embodiments of vapor deposition processes are those which are carried out under conditions of subatmospheric pressure. A number of techniques have been developed to increase the film deposition rate using these techniques, for example electric fields, magnetic fields and radio frequency or microwave excitation have been used to increase the moment of the reactant particles in vapor coating compositions upon their application. In addition, wave control means have been used to direct the vapors of coating compositions towards particularly limited target areas.

See U.S. Patent Nos. 3,114,652 and 3,561,940.

It has been found that the uniformity of films produced by chemical vapor deposition and the rate of chemical vapor deposition or film build-up can be significantly increased by directing reactant vapors via a nozzle to a substrate under certain flow conditions and preferably using certain nozzle-substrate distances. using nozzles having a special shape.

An evaporating coating reactant is evaporated into a vapor phase carrier or a gaseous carrier and is supplied through a nozzle and directed towards a heated substrate. The temperature of the substrate and the reactant is such that upon contact with the substrate, the reactant reacts to form an adhesive coating on the substrate. In order to ensure rapid, efficient and uniform precipitation of the coating, the gaseous mixture containing the coating reactant is directed through the nozzle with an Eeynold number of at least 2,500. For high speed coating of a continuous strip or sheet of glass, it is preferred that the Reynolds number of the flowing gaseous mixture be at least about 5,000.

The evaporable coating reactant is usually a material which is in solid or liquid form at room temperature, although the preferred reactants are usually solid at room temperature. The reactant can be evaporated by conventional methods, for example boiling in case it is liquid, or if the reactant is solid it can be evaporated by inserting it on a heated plate, is mixed with an inert material, such as true, and a heated carrier gas passes through the mixture or it is fluidized with a rapidly moving stream of carrier gas with heating of the fluidized mixture. According to the preferred embodiments of the present invention, the reactant is dissolved in a suitable solvent, after which the solution is injected into a hot carrier gas in order to evaporate the solvent and reactant.

The reactive coating materials preferred for use in the present invention include pyrolysable organometallic salts of metals of groups 1b to VIIb and of group VIII of the Periodic Table. Preferred organometallic salts include beta-diketonates, acetates, hexoates, formates and the like. tonates of iron, cobalt and chromium are especially preferred as reactive constituents in the present coating compositions. Although the coating reactants which are preferred for use according to the invention are pyrolysable materials, for example β-cetylacane other types of reactants may also be used. hydrolytic reactants such as fluorinated beta-diketonates, especially acetylacetonates, and metal dicumen are used. Reactants, which require the presence of significant amounts of other cooperating reactants such as oxygen, hydrogen, halogens or the like, can also be used. As already stated, the preferred evaporation method comprises a first dissolution step, so the reactant or reactants used should be readily soluble in a suitable solvent.

A variety of aliphatic and olefinic hydrocarbons and carbon halides are suitable as solvents for carrying out the indicated methods. One component solvent system, especially a solvent system using methylene chloride, is effectively used in the present invention.

Solvent systems using two or more solvents have also been found to be particularly useful.

Some representative solvents which can be used in the present invention include: methylene bromide, carbon tetrachloride, carbon tetrabromide, chloroform, bromoform, 1,1,1-trichloroethane, perchlorethylene, 1,1,1-trichloroethane, dichloroiodomethane, 1,1,2 tribromethane, trichlorethylene, tribromethylene, trichloromonofluoroethane, hexochloroethane, 1,1,2,2-tetrachloro-2-chloroethane, 1,1,2-trichloro-1,2-dichloroethane, tetrafluorobromoethane, hexachlorobutadiene, tetrachloroethane and the like.

Other solvents may also be used, especially in the form of mixtures of one or more organic polar solvents, for example an alcohol containing 1 to 4 carbon atoms and a hydroxy group and one or more aromatic non-solvents. polar compounds such as benzene, toluene or xylene. The volatility of these materials makes their use somewhat more difficult than the use of the above-mentioned group of preferred halogenated hydrocarbons and hydrohalogens, but they have some economic usefulness.

According to a preferred embodiment of the invention, a solution of a reactive organometallic salt in an organic solvent is directed towards an evaporation chamber. The evaporation chamber is designed to provide a heating element which heats the space surrounding the element to a temperature sufficient to evaporate the coating solution in the space instead of only evaporating the liquid which is in contact with the heating element itself. A carrier gas is directed transversely and away from the heater to trap the coating composition to be mixed with it for the purpose of increasing its evaporation rate and passing the vapors through the heater to the substrate to be coated. Vapors of solvent and reactive organometallic salt are directed from the evaporation chamber to an elongate manifold, which is arranged across the width of a heated substrate to be coated.

An elongate nozzle is connected to this manifold to direct the vapors towards the substrate.

According to a preferred embodiment, the elongate nozzle has, as a minimum cross-section, a uniformly converging shape in order to effect a substantially continuous acceleration of the boundary layers in the steam which passes therethrough. The largest cross-sectional dimension of the nozzle is slightly smaller than the corresponding substrate width so that a substrate, which is placed with the surface facing the nozzle, extends beyond the largest dimension of the nozzle at both ends. This condition ensures the maintenance of a substantially uniform pressure drop along the largest dimension of the nozzle and prevents leakage of a disproportionately large amount of vapors directed through the nozzle at each end of the nozzle and consequently the entire amount of steam is in good contact with the substrate.

The nozzles according to the invention are elongate to be arranged transversely over a substrate. Relative movement between the substrate and the nozzle along the direction perpendicular to the elongate dimension of the nozzle allows full coverage of the substrate by means of the nozzle.

The smallest section of the nozzle (ie the cross-section formed by a plane perpendicular to both the plane of a substrate uniformly separated from the nozzle opening and perpendicular to the elongate dimension of the nozzle) is substantially uniform to its shape and dimension over the entire effective elongated dimension of the nozzle. The elongate nozzle has at its smallest cross-section a converging shape which converges substantially uniformly and evenly from its inlet to its outlet. This shape causes the boundary layers of steam and gas flowing through the nozzle adjacent the nozzle walls to accelerate over substantially the entire length of the nozzle. According to a preferred embodiment, the smallest cross section is defined as a cubic parabola, preferably with the walls at the exit and with 1 to 10 percent of the nozzle length approaching the exit parallel to each other. With such a shape, the flow not only accelerates when passing through the nozzle but also accelerates at a constant speed, whereby special stability is imparted to the flow and flow pulsations are eliminated.

The largest cross-section of the nozzle is usually rectangular, especially for nozzles with an elongated dimension which is more than about 10 times as large as the inlet width at the smallest cross-section. This is simply a nozzle shape that can be constructed easily and economically using conventional machining technology and equipment. With this preferred shape, two elongate nozzle portions can be machined separately to the desired shape and mounted in parallel relationship facing each other to form a nozzle. For a short nozzle having an elongated dimension, which is less than about 10 times the width of the smallest cross-section, the largest cross-section should preferably be reduced from entrance to exit in the same way as the smallest cross-section. Throughout the specification, an elongate nozzle means a nozzle having an elongate dimension that is at least 2 times and preferably at least 5 times the inlet width of the smallest cross section of the nozzle. The nozzle according to the invention preferably has a contraction ratio of at least four and especially of at least about six.

The effect of such contraction conditions is that irregular flow conditions, which can develop upstream if the nozzle is leveled and eliminated over the length of the nozzle so that an even and uniform flow is achieved along the entire area, in which stroke occurs against the substrate with meadow-substrate contact density symmetrical. in the plane of the substrate by means of a plane which cuts the nozzle perpendicular to its smallest cross-section. The contraction ratio is the ratio between the flow surface of the nozzle inlet and the flow surface of the nozzle outlet. The side of the nozzle facing a substrate to be coated is located in such a way in relation to a support for substrates to be coated that the distance between the nozzle side and the area closest to it during the coating process is at least 0.5 times the width of the nozzle at its exit. Preferably, the distance-nozzle width ratio is at least 0.65 and more particularly is between 0.9 and 5. According to the most preferred embodiments, the ratio is between 1.25 and 5.

Evaporator or evaporator and manifold in the coating apparatus of the invention are operated at sufficient pressure to cause vapor flow through the nozzle at a Reynolds number of at least 2,500 and preferably at least about 5,000 in order to ensure rapid, efficient and uniform precipitation of the coating.

The device and method according to the invention can be used for applying coatings to a plurality of susceptible substrates. Refractory substrates, for example glass, glass ceramics, ceramics, porcelain coated metals and the like are particularly suitable for coating in accordance with the present invention. Other materials such as metals, plastics, paper and the like can also be coated according to the invention. In particular, the invention is useful for coating flat glass. The resulting flat metal. with transparent metal oxide coatings. oxide-coated glassware has been found to have particular utility for architectural applications.

Fig. 1 is a partial perspective view, cut away, of the preferred device for carrying out the present invention, showing the flows of remorse and other fluids used in accordance with the invention.

Fig. 2 is a partial sectional view of the preferred evaporator, manifold and nozzle according to the present invention and shown in combination with a sheet of float glass supported so that it faces the nozzle.

Fig. 3 is a partial sectional view through a preferred device taken along section line 3-3 of Fig. 2.

Fig. 4 is a partial sectional view of the preferred evaporator device of the invention taken along section line 4-4 of Fig. 3 showing the particular relationship between the heating element located therein and the chamber space with its inlets, outlets and partition devices to provide evaporation of coatings the compositions which according to the invention are used within the space of the chamber rather than to give evaporation in contact with the heating element itself. Fig. 5 is an enlarged sectional view through a preferred nozzle according to the invention in combination with a suitable manifold for distributing steam to the nozzle.

Fig. 6 is a sectional view through a preferred nozzle of the invention taken along section line 6-6 of Fig. 5.

In carrying out the invention, it is important that the Reynolds number, which characterizes the flowing vapors which emerge from the nozzle and are directed towards the substrate, which is coated, is kept higher than about 2,500. Although a Reynolds number of at least 1,700 assures that the steam flow is completely turbulent, it has now been observed that the Reynolds number must be at least about 2,500 in order for the flow to be substantially uniform over the entire area of impact to the substrate, as determined by inerferometric technique and by the uniformity of the resulting precipitates.

In carrying out the invention, it is preferred that the boundary layer of vapors and gases flowing through a nozzle and directed towards a substrate to be coated be accelerated during passage. This prevents undue flow pulsations and increases the nozzle through the nozzle. speed for and uniformity of coating precipitates. preferably has a contraction ratio of at least six.

Reynolds numbers are defined by the following classical equation: NRe = W .j °. LÅQ. Reynolds' speech is dimensionless. The symbols W, jçoch / 2 represent flow rate, density and dynamic viscosity of the steam stream. L is a characteristic length defined at the point where the other variables are determined. According to known hydraulic principles, the characteristic dimension L, which is relevant in the defined ratio, is the hydraulic diameter, which is defined as four times the cross-sectional area of the nozzle outlet divided by the wet circumference of the nozzle outlet. The flow, density and vapor viscosity are all characterized in the equation as the values of these properties at the nozzle outlet. The present invention is explained in more detail below with a detailed description of the device and method.

Referring to Fig. 1, a substrate, for example a glass sheet 11, is provided for coating. The glass sheet 11 is usually supported, preferably in the horizontal plane, and is supported by means which can move or transport the glass sheet 11 along a path, as indicated by the arrow in the lower right part of Fig. 1. The coating device according to the invention is mounted facing the glass sheet 11 and comprises a 10 15 20 25 §O 55 40 'with outlet opening located on the inside of the evaporator chamber 14. 7316813-0 evaporator or evaporator unit 12 and a steam distribution unit 15.

The evaporator assembly 12 comprises an evaporator chamber 14 which, according to a preferred embodiment of the invention, comprises a cylindrical chamber containing elements for evaporating the reactants, which elements are described in more detail below. The evaporator assembly 12 further includes means for supplying a reactant 15 and means for supplying a carrier gas 16.

A reactant is passed via a solution line 17 to a series of solution feed lines 18, each connected to a syringe tip 19. The solution line 17 is surrounded by a coolant line 20, which is divided into front and return flow portions by a partition 21. atomizing gas, preferably air , each syringe tip 19 is supplied via a series of atomizing feed lines 22, all of which are connected to a line 23 for atomizing gas. The entire reactant supply means 15 is mounted on the evaporation chamber 14 by means of a series of caps 24, which surround the conduits and by means of bolts or other means connected to a series of coatings 25 welded to the evaporator chamber 14.

The carrier gas supply means 16 comprises a carrier gas manifold 26 mounted on the evaporator chamber 14 by means of a holder 27. A series of carrier gas supply lines 28 are mounted to the carrier gas manifold 26, each such conduit being connected to a carrier gas preheater 29, which in in turn is connected to the evaporation chamber 14 in such a way that the heated carrier gas can be directed into the chamber. The preheaters 29 preferably consist of electric 7 resistance heaters, each of which has an electric power outlet BO connected to a source of regulated electric power (not shown).

The evaporation chamber 14 may be of simple structure, but in case it has an extended length, it is preferably of modular construction with a series of rather short evaporation chambers 14 connected end-to-end by means of evaporation chamber couplings 31, which interlock the individual chambers. Inside the evaporation chamber 14 there are elements for extending a reactant and other materials such as a solvent. A heater 32 is mounted in the evaporating chamber 14 in such a way that the chamber is divided into two parts, all incoming material entering one part and outgoing steam escaping from the other. The heater E2 is designed so that the vapors can pass through it from the inlet part to the outlet part of the evaporator chamber 14. A preferred heater consists of a heat sink and tubular heat exchanger, a thermal heater regulated heat exchanger fluid is supplied to its pipes.

The heater 32 is mounted in the chamber 14 on fittings, which effectively also constitute distribution plates 33 for the carrier gas, welded or otherwise connected to the inner walls of the chamber 14. The distribution plates 33 for the carrier gas are so shaped and connected to the chamber 14 that an enclosed manifold space is formed between each plate 33 and the closely spaced chamber wall. The carrier gas distribution plates 33 are provided with a series of openings which allow free flow from the inlet portion of the evaporator chamber 14, where the gas is mixed with sprayed reactant and solvent which evaporates them.

The gaseous mixture, which contains a reactant in the inlet part of the evaporator chamber 14, passes through the heater 32, which sets or carefully regulates the temperature of the mixture which enters the outlet part of the evaporator chamber 14. The heater preferably has a high heat capacity in relation to the mass of flowing gaseous mixture, so that thermal stability is ensured.

In the outlet part of the evaporator chamber 14 there are a series of steam outlet conduits 34 which extend outwards through the wall of the evaporator chamber 14 and have many inlet openings near their inner ends. The inner end of each steam outlet conduit 34 is preferably covered with an umbrella 35 which deflects any comminuted material entering the chamber or formed in the chamber, thereby preventing the material from clogging the steam outlet conduit.

An exhaust steam heater 36 surrounds the steam outlet lines 34. The steam outlet heater 36 has two cavities, an inlet cavity and a return cavity, which are connected to a heat exchanger fluid recirculation system (not shown). In operation, hot fluid, such as oil, is circulated through the steam heater 36 to control the temperature of the gaseous mixture discharged from the evaporation chamber 14.

A coupling 37, preferably a flexible coupling, is connected to each steam outlet line 34, which coupling connects the evaporator assembly 12 to the steam distribution assembly 13. The steam distribution assembly 13 comprises a steam manifold or chamber 38 having two steam channels 39 separated by separate steam channels 39. partition 40 and sheathed with internal and external heat-regulating fluid cavities 41 and 42.

In operation, hot fluid, such as oil, is circulated through the inner and outer cavities to control the temperature of the gaseous mixture flowing through the vapor channels 39.

The steam ducts 39 of the collecting chamber 38 open into nozzles 43, preferably converging nozzles. Each nozzle includes opposing nozzle walls 44 connected to the chamber 38. Preferably, each nozzle wall 44 is provided with a cavity 45 through which hot fluid, for example oil, can be directed to precisely control the temperature of a gaseous coating mixture directed through the nozzle. paragraph 43 against the substrate ll.

The present coating apparatus and method can be used in combination with a number of other methods and substrates, such as in papermaking, sheet metal rolling and the like. The present method can be used to apply a continuous strip or series of separated or separate substrates. According to the preferred embodiments of the invention, a continuous flat glass is coated.

This can be flat glass made by the casting glass process, in 9 by any machine glass process (Colburn, Fourcault or Pittsburgh Pennvernon process) or by a float method.

The present invention can be effectively used to apply a coating to a substrate in a vertical, horizontal or otherwise oriented plane and this feature is particularly valuable and unique to the invention.

According to a particularly preferred embodiment of the present invention, a newly formed strip of float glass is coated. The strip can be easily coated on either of the main surfaces of the present invention and the following description relates to the coating of the upper surface of the glass strip.

Reference is made to Figs. 2, 5 and 4 as well as to Fig. 1, in which the device according to the invention can be observed in a particularly preferred environment constituting the space between a float-forming bath and a cooling furnace. __ f A continuous glass strip 11 is shown on a bath of molten metal 46, for example molten tin, the contents of a bath 47 comprising a refractory bottom and side and top walls 48 surrounded by metal lining "'49.

The belt 11 is lifted from the molten metal 46 at the exit end of the bath chamber 47 on lift rollers 50, which are suitably mounted and driven by conventional roller pulling means coupled to a drive motor (not shown). Carbon blocks 51 are spring-loaded and press against the bottom v u I.

L n of the rotating rollers 50 for the purpose of removing material which may fall on the rollers. The carbon blocks 51 are supported within a refractory extension of the bath chamber 52. Materials which are removed from the rollers and fall into this extension 52 can be easily removed on an intermittent basis.

The glass strip 11 is fed into a cooling furnace 55 with a plurality of cooling rollers located therein. Conventional drive means are provided for rotating the rollers 54. Each cooling roller 54 exerts a pulling force on the glass of sufficient size to pass the glass through the cooling furnace, wherein its temperature is regulated to release permanent stress and tension in the glass.

The rollers 54 form part of a means for transporting newly formed float glass from the float bath chamber 47 through an evaporation coating chamber 55 and thereafter through the cooling furnace 55.

The atmosphere in the bath 47 consists of a reducing atmosphere containing nitrogen gas and a small amount of hydrogen gas to ensure that oxidation of the molten metal 46 is avoided. Usually the atmosphere contains about 90 to 99.9 percent nitrogen, with the remainder being hydrogen. The atmosphere is maintained at a pressure which slightly exceeds the ambient pressure, for example 2.5 to 12.5 mm water columns, in order to substantially prevent intrusion of the surrounding atmosphere into the bath 47.

In order to maintain the atmosphere and allow the passage of the glass ribbon from the bath 47, the exit end of the bath is provided with a series of curtains or drapes 56, which are guided on the glass ribbon and serve as means for separating the slightly compressed atmosphere in the evaporation coating chamber 55 from the baths 47. These drapes or curtains 56 are usually made of flexible asbestos or fiberglass material which does not damage the glass and withstands ambient temperature, i.e. a temperature of about 558 to 648 ° C. Additional draperies or curtains 57 of similar material are provided at the entrance of the cooling furnace 55, the latter draperies serving as means for separating the cooling furnace 55 from the evaporation coating chamber 55. The steam coating chamber 55 is provided with vacuum caps 58 with inlets arranged both upstream, near the bathroom, and downstream the cooling furnace. The vacuum caps 58 extend vertically upwardly to a pair of outlet pipes 59 and are sufficiently spaced to provide the required space for supporting I-beams 60 and for the steam coating device including the evaporator assembly 12 and the steam distribution assembly 15 as well as associated equipment. The vacuum caps 58 are movably supported on the I-beams 60 by means of wheels 61, which rest on top of the I-beams 60. The I-beams are arranged across the path of the glass strip 11, which moves from the bath chamber 47 to the cooling furnace 55.

The vacuum caps are kept in separate relationship by means of a cross joint 62. ... e-que m ...

The outlet pipes 59 are mounted on holders 65, on which wheels 64 are mounted, which wheels rest on grooves 65 belonging to a supporting overhead beam 66. The entire vacuum housing assembly comprising the vacuum housing 58 and the outlet pipes 59 can be moved transversely in relation to the path of the glass strip in order to completely remove the unit from the flow line for maintenance and repair. This removal is accomplished by causing the assembly to move along beams 60 and 99 while rotating on the support wheels 61 and 64. The steam coating assembly is supported in the steam coating chamber 55 f by I-beams 60 by means of a support holder 67. Support wheels 68 for the steam coating are mounted on the support bracket 67. The support wheels 68 for the steam coating rest on I-beams 60 and one of these has a groove 69 mounted thereon. The shape of the groove 69 and the cooperating support wheel 68 is such that lateral movement of the assembly in relation to the track and the I-beams are prevented. å i L The steam coating assembly comprises, in addition to the evaporator assembly 12 and the steam distribution assembly 15, a mechanical structure for supporting these operating elements. This mechanical structure includes a motor 70 and jacks 71 for raising and lowering the assembly in order to place it closer or farther away from the ground, | which is to be coated.

Transverse arms 72 for steam coating hang from the steam support support holder 67. A motor support 73 and jack support 74 are mounted on the cross arms 72. The motor 70, preferably a DC motor 5 of variable speed, is mounted on the motor support 75. A drive shaft 75 is coupled to this motor 70, which shaft is in turn coupled to screw jacks 71. In each jack 71 there is a suitable gear for driving a screw shaft in vertical motion.

Screw shafts 76 are connected to the drive shaft 75 via jacks 71 connected to a gear. By driving the drive shaft 75 by means of the motor 70, the screw shafts 76 are caused to move vertically to raise and lower the steam coating assembly. Brackets 77 are mounted on the screw shafts 76. Support arms 78 are connected to and hang from the brackets 77, which arms are connected to cross plates 79.

An evaporation arc support 80 is mounted on the cross plates 79, and the evaporation chamber 14 is connected to this support by means of bolts or other means.

As briefly described above, according to a preferred embodiment of the invention, a carrier gas, preferably air, is required to be supplied to the evaporation chamber 14 to mix with the finely divided jet 10 15 20 25 §O 35 40 13 '7316813-0 of coating composition, which is based on the jet nozzle tips 19 in order to increase the evaporation rate of the coating material and to then pass the mixture through the heater 32 in order to further heat the combination for final delivery to the substrate to be coated. The carrier gas is supplied to the evaporator from manifolds 26, which are preferably made of pipes mounted on the unit by means of holders 27.

A flexible hose 28 is connected to the carrier gas manifold 26 and is directed through heating elements 29 to coupling details which pass through the wall of the evaporator chamber 14 and open into the space formed by the air distribution plates 33 and the wall of the evaporator chamber.

Power is supplied to the heaters 29 from an electrical line 81, which passes through a supporting distribution line 82 mounted on the holders 27 and 83.

The structural properties of the presently unreacted or coated device are shown in Figs. 2, 3 and 4. The tax coating composition beds and carrier gas discharged from the nozzles 43 to the substrate 11 fill the vapor coating chamber 55. The unreacted vapors and gases are removed from the middle chamber. vacuum caps 58. to reduce the build-up of precipitates to a minimum or even to avoid it on irregular construction surfaces, which can result in flaking and deposition on the substrate ll causing defects, the steam coating assembly is encapsulated in a steam coating protection 84. The steam coating can be pre-coated. with reinforcement plates 85.

It is connected to the coating assembly by connection with the cross plates 79.

The cross plates 79 are, as previously stated, connected to the support day assembly 78 and are further connected to the support 80 for the evaporating arc.

As previously described, the evaporator chamber 14 is connected to the support 80 for the evaporator arc.

The cross plates 79 are provided with access holes 86. The space between the vapor barrier protection 84 and the vapor collection pipe 38 is preferably filled with thermal insulation 87, for example mineral wool, asbestos or the like.

As shown in Fig. 3, a meadow coating assembly may have a modular structure for the purpose of bridging the entire width of a conventional g-shaped glass strip. Modular shape is preferred for easy maintenance and repair of the equipment.

Individual evaporation chambers 14 with suitable equipment are connected together to form a unit which bridges the entire width of the belt. Although the evaporator 14 may have a modular shape, the meadow manifold 58 and the steam nozzles 43 preferably consist of simple units. of the material to be coated.

In this way, the vapors are uniformly distributed across the width for the purpose of reference to Figs. 5 and 6, the details of the steam distribution manifold and the steam nozzles are shown.

The coating vapors are uniformly distributed along the substrate by means of the vapor collection tube or chamber 38. The construction of a particularly preferred combination of chamber 38 and nozzle 43 is shown in the enlarged views of Figures 5 and 6. of the collection chamber or tube 38 which bridge the width of a vapor barrier. glass strips to be coated are much larger than the width of the manifold. | For example, to coat a glass strip with a width of about 3 m, the length of the manifold, denoted by d in Fig. 6, is approximately also 3 m. Usually the width of the manifold is 0.3 m or less. The steam collection pipe 38 comprises a plurality of steam channels, which are elongate and separate from each other at the outlet ends, but the plurality of couplings 37 meet in a common channel at their inputs. which bring vapors from the evaporator 14 to the manifold 38, are connected to the manifold 38 along the entrance of the common channel.

Each vapor channel 39 may preferably be constructed with at least two opposite curves so that the path of movement of vapors passing through the channel must change direction at least twice. In this way, the uniformity of the steam distribution along the length of the channel is increased. Although partitions can be arranged in the ducts in order to further stop the steam flow and distribute the steam along the length of the ducts, the simple design without partitions but with a changed flow direction is preferred. In the preferred embodiment, there are no areas of stagnation and no protruding bodies which can create eddy currents of considerable size.

Cavities 41 and 42 surround the steam ducts 39 to contain a heating or cooling fluid as desired according to cross-flow flows illustrated in Fig. 6. These chambers 41 and 42 extend along the length of the steam manifold 38 and are connected to a source of heating. or cooling fluid (not shown). According to the preferred embodiment, hot oil is supplied to the chambers. Nozzle wall portions 44 are connected to the steam manifold 38, which wall portions form nozzles 43 which direct the vaporized coating composition and the carrier gas toward the substrate 11 to be coated.

As can be seen from Fig. 6, the nozzles 43 are elongate and in plan view they appear as slots. The cross section of the nozzle openings seen in parallel with the largest slot dimension, e, illustrates that preferred nozzles taper considerably from entrance to exit. The contraction of each slit is such that vapors which pass through the slit are continuously accelerated along the length of the slit in a transverse length ¿¿Era 10 15 20 25 30 55 40 7316813-0 15. In this way, the boundary layer of vapors adjacent to the slit wall is reduced to a minimum and the circumference of the slit is uniformly wetted by the vapors so that outgoing vapors are evenly and uniformly directed towards the substrate. The present nozzles are characterized by a contraction ratio, which is the ratio c / a between the inlet surface and the outlet surface of the nozzles illustrated in Figs. 5 and 6.

Preferred flow conditions to achieve efficient and equal T cs. shaped coating is described below and the conditions described are defined as the conditions prevailing at the initial nozzles. End.

The smallest dimension of each nozzle outlet, indicated as "a" in Fig. 5, dictates the distance "b" between nozzle outlet and the ratio b / a is preferably in the range from 0.75 to 10. In the especially preferred embodiments, the ratio b / a between 1.25 and 5. In the most preferred range for distances, indicated by the ratio b / a, the rate of coating precipitation is considerably greater than at smaller or larger distances. ¿Each steam duct 39 preferably has a volume of at least E about six times the volumetric flow of the duct per minute. By ; this ability to hold vapors passing through the duct serves the duct as a calming section to smooth out residual velocity variations resulting from the flow of separated streams starting from the flexible connections 37. As previously stated, the vapor ducts 39 preferably reorient vapor flow and tends to uniformly pre- Shape and size of steam- For the substrate. divide the steam along the length of the manifold 38. the channels 39 are observed to cooperate with the shape of the nozzles 43. In the event that the contraction ratio of the nozzles, c / a, is increased, especially above about 5 to 6, the capacity or volume of the steam ducts 39 can be reduced without detrimental effect.

Each nozzle 43 is formed by two parts 44, each having a curved side, coupled to the manifold 38 with its curved surfaces facing each other. Each part may be provided with a channel 45 for containing a fluid, for example hot oil, for regulating the temperature of vapors and gas which are released. In the preferred embodiment, hot oil passes through parallel channels 45 and then. through the channels 41 and 42. The temperature of the oil to and from the nozzles can be measured and the temperature which from such measurements is calculated to constitute the nozzle temperature is the temperature used in indicating steam flow conditions at each nozzle outlet.

The curved surfaces which form the flow area in each nozzle are machined evenly in order to avoid the creation of small obstacles or scratches which would give the steam and gas flow local disturbances.

According to a preferred embodiment, the nozzle parts are made of machined steel or other base metal, and the curved inner surfaces are plated with an easily machined metal, for example gold or other precious metal. A metal finish of at least about 16 x 10 "; mm and preferably about 4 x 10 -5 mm is satisfactory. When the contraction ratio; c / a is large enough, said metal finish may be less smooth without D effect. The radius is at least at the entrance and According to a particularly preferred embodiment, the radius of curvature increases monotonically (ooh preferably constantly) as a function of the E distance from the nozzle inlet to its outlet. For easy construction of the device, the nozzle parts 44 are machined to a fixed position. different radii in separate areas (eg I, II, III and IV) along the nozzle§_path length ._Each area_ is evenly machined_§ to merge into the next. ”The exit edges of the nozzle parts preferably form sharp, well-defined corners so that facing a portion of the nozzle portions, is not wetted by outgoing vapors and gas.The edge facing the substrate of each nozzle portion 44 should be about 900 relative to the portion surface and is preferably about 870 so that the edge has an angle of about 30 up away from the nozzle exit in relation to the plane of the substrate. The flow conditions maintained in the practice of the invention are defined at each nozzle outlet. With reference to Fig. 5, the following parameters are considered. The characteristic length, N, fs used in determining the Reynolds number of the steam outlet, is the hydraulic diameter of the nozzle, defined as four times the cross-sectional area of the nozzle divided by the wet circumference of the nozzle opening: D = 486 2 (a + e) Since a is much smaller than e approaches the value of the hydraulic diameter 2a. The temperature of the flowing meadow-gas mixture is considered to be the average oil temperature across the nozzle and is determined from measured temperatures for inlet and outlet oil. The density and viscosity of the meadow-gas mixture are determined to be the density and viscosity of the mixture at nozzle temperature and pressure. in the evaporation chamber. In general, the properties of the curvature of the inner surfaces of the nozzle are such that the curvature of the carrier gas at this temperature and this pressure is satisfactory.

The flow rate is determined from the mass flow to the evaporator divided by the density of the mixture, as indicated, and further divided by the total area of the nozzle outlet openings (the number of nozzles multiplied by [a. E]).

The following exemplary embodiments illustrate the use of the nozzle according to the invention in several different Reynolds numbers and with varying distance nozzle substrates. z EXAMPLE I A test device with a single nozzle of the type described above having the following properties is used for the tests described below. The nozzle used has a contraction ratio of close to six. Referring to Figures 5 and 6, the nozzle can be illustrated by the following table of dimensions. The largest dimension, e, decreases from the nozzle input to its output in the same way as the smallest dimension, a at the output and c at the input. The contraction ratio thus constitutes the relationship between the cross-sections for input and output. at the outlet 3 7316813-0 18 The hydraulic diameter is indicated for points along the nozzle blade: ¿f.

Nozzle length Maximum dimension Minimum dimension Simplified (e) (c to a) diameter Input .0 mm 386.0 mm c = 38.6 mm 70 mm 1 585.9 58.5 70 2 385.8 58.4 70 5 585, 5 58.1 59 4 585.1 57.7 69 5 584.5 57.5 58 6 584.0 56.7 _ 67 7 585.5 56.1 56 8 582.5 55.5 55 9 581.6 54.8 64 10 580.6 34.0 62 15 574.5 50.1 55 20 366.1 26.5 49 25 556.7 25.4 411 50 546.6 '20, 9 59 55 556.1 18 , 8 56 40 525.8 17.2 55 45 515.9 15.8 50 50 506.5 14.7 28 55 297.9 15.8 i 25 60 290.0 15.0 25 65 282.9 7 12 , 4 24 70 276.6 11.9 257 75 271.1 11.5 22 80 266.5 11.1 21 85 262.2 10.8 21 90 258.7 10.6 20 95 255.9 10.4 20 100 255.7 10.2 20 110 250.9 10.1 19 120 250.0 _ 10.0 19 150 250.0 10.0 19 10 15 20 25 50 35 40 7316813-0 19 .The device comprises a motor-driven fan, which can deliver 5,000 liters of gas per minute. A heating coil with a power of 4 kilowatts is arranged downstream of the fan, the heating coil being located in the line through which the gas flows from the fan to the nozzle.

A thermocouple is located in the pipe wall immediately upstream of the nozzle, and this thermocouple is connected to a temperature controller, which in turn is connected to and regulates the power to the heating loop. A support for the base is arranged opposite the nozzle opening. the support, and a series of thermocouples are provided to keep the support of the substrate provided with means for heating the temperature of the substrate. a flat surface in a plane perpendicular to a plane formed by the center of the nozzle along the axis of emitted gas flow.

An optical interferometer (Mach-Zehnder) is arranged in ambient relation to the test device. The interferometer is located so that the center of its line of sight is in the plane formed by the axis of the gas flow and is parallel to the plane of a substrate.

The interferometer uses two coherent monochromatic light beams, each with a wavelength of 546 nanometers (mercury arc lamps with narrow band green filter). Since the anticipated flow fields to be studied have a considerable temperature gradient, a system of one rotational speed was used, such as the optical interference with rotating mirror in the interferometer. gives 200 times interference was used. are recorded using a camera and the resulting photographs reveal temperature profiles by comparing changes in outer parts expressed as widths of the outer parts according to the well-known principles of interferometry. Derived from the Gladstone-Dale ratio, a change in n outer ranges indicates a temperature difference of n.

The device was first operated with a nozzle base distance of twice the width of the nozzle (once the hydraulic diameter).

Only heated air was emitted at several flow velocities characterized by Reynolds 900, 1,500, 2,000, 2,500, 4,000 and 5,000.

The heated gas (air) emitted to the substrate must rotate 900 in the vicinity of the substrate. The beginning of this rotation is observed from the interoferograms (the photographs of the interfered light) about 0.8 times the nozzle width, a, above the substrate. At Reynolds numbers at and higher than 2,500, a pronounced sharp boundary area with uniform density is observed near the ground. This indicates uniform -1 and 15 15 precipitation conditions and effective precipitation conditions. Even at and above a Reynolds number of 2,500, the width of the effective flow, which cooperates with the substrate, is observed to be much larger than the nozzle width, so that the coating reactants can be efficiently spread over the substrate surface.

When the experiments are repeated with substrate temperatures in the range from 500 to 55100, no significant variation with the substrate temperature is revealed.

The experiments are repeated with varying nozzle base distances.

Distance ratios of b / a = 4, b / a = 2 and b / a = l are examined.

For a distance ratio of 4, the interferograms reveal gas density maps, which show a sufficiently wide range of non-uniformity near the base for uniform coating at a Reynolds number of 5,000. At lower Reynolds numbers, the area decreases and at a Reynolds number of about 2,500, the density map indicates the possibility of non-uniform coating.

For a distance ratio of 2, the interferograms reveal that the gas density maps show a divergence of the current into a uniform coating area starting at about 0.67 times the nozzle width above the substrate. At this distance ratio, flow oscillations, which were visible at larger distance ratios, are absent and the flow and density fields remain uniform with respect to time. Even below a Reynolds number of 2,500, a small uniform coating area is observed and above a Reynolds number of 2,500, the width of the area exceeds the nozzle width and at a Reynolds number of 5,000, the width of the area is about 2 times the nozzle width.

“For a distance ratio of l, the interferograms reveal gas density maps with sharply reversing flows, which create variable pressure fields. This tends to destroy the effect of the outlet flow and the higher Reynolds numbers within the preferred range are reached with a uniform coating range, which is still limited to approximately the nozzle width.

Further reduction of the distance ratio requires higher Reynolds numbers. Despite the possible a priori idea that improvements can be achieved by moving the nozzle closer to the substrate, boundary penetration, which can be expected to occur, can be observed offset by non-uniform conditions, which are experimentally observed. Although the example described above establishes the significance of Reynolds' speech and the nozzle-substrate distance for vapor deposition as long as their significance can be deduced from gas density variations and other conditions in the vicinity of the substrate, the following descriptions are described. For example, coating a glass substrate according to the preferred embodiment of the invention. EXAMPLE II The experiments according to Example I are repeated using a simple flat-walled opening with the same input and output cross-sectional surfaces as the nozzle according to the invention instead of the nozzle of the invention. At all Reynolds numbers and distances, the observed flow conditions near the substrate are more irregular than in Example I.

EXAMPLE III The device shown and described above is placed across a strip of glass made by the float glass method between a float-forming bath and a cooling furnace.

The nozzle is machined to four radii over a nozzle length of 6.04 cm. The width of the nozzle inlet, c, is 12.1 cm and its outlet width, a, is 0.16 cm. The radius of the nozzle is: area I 7.0 cm, area II 2.1 cm, area III 28 cm and area IV infinite- häæn, ie. having flat surfaces.

A continuous strip of clear glass with a width of about 3 m and a thickness of about 0.6 cm is passed under the device at a linear speed of about 6.4 m per minute. The glass is a conventional soda glass with a visible light transmission of about 88 percent.

A coating solution is prepared. The solution has the following composition calculated per 5.785 liters: Iron acetyl acetonate 510 grams Chromacetylacetonate 150 grams Cobalt acetyl acetonate 55 years Methylene chloride 3.785 liters The coating solution is fed to the solution line 17 at a speed of about 0.76 liters per minute, at and a temperature of about 2100. Atomized air is supplied to the atomizing gas line 23 at an overpressure of about 0.55 kp / cmg and a temperature of about 2100.

Carrier air is supplied to the carrier gas manifold 26 at an overpressure of about 4.2 kp / cm2 and an approximate speed of 4,830 standard liters / min. (170 SCFM). The carrier air is heated to about 26,000 in the preheaters 29 and supplied to the evaporator chamber 14, the air velocity through the distribution plates 53 being about 1.5 to about 3 m per minute.

The sensitive heat in the air is sufficient to vaporize the coating solution and establish the resulting temperature of the air-vapor mixture in the range of about 204 to 216 ° C. 10 15 20 25 30 ”355 40 7316313-of 22 Hot oil is supplied to all heaters at a temperature of about 200 ° C. The coating mixture leaving the evaporation chamber 14 and passing through the collection chamber 38 and the nozzles 45 thus has a stabilized temperature of about 20 ° C. The glass temperature under the nozzles is about 564 ° C.

The nozzle base distance is b / a = 2. The conditions described give a Reynolds number at the nozzle output of 5,000. The Reynolds number is based on the viscosity of air at 21000 and the density of the mixture of air methylene chloride at 21000 and pressures of 1 atmosphere.

The mass flow is known directly from the inlet to the evaporator.

The device is operated for a period of 20 minutes to coat about 18 m2 of glass. The resulting coating is uniform across the glass surface, with the average visible light transmittance of the coated glass being 40 percent and the transmittance variation being less than f 2 percent except for the extreme marginal edges of the glass, which extend beyond the largest dimension of the nozzles.

The coatings are found to be more uniform and show a much finer grain appearance than coatings produced by spray methods using the same coating material. EXAMPLE: v The method of Example III is repeated several times with the exception that in all cases some procedural parameter is changed in order to determine its effect on the coatings produced.

First, the starting flow method is repeated with a Reynolds number of 2,500. The resulting coating exhibits excellent quality as in Example III despite the fact that the total average transmittance is only 50 percent, indicating slightly less coating or precipitation efficiency than according to the preferred embodiment of the invention.

Second, the starting flow method is repeated with a Reynolds number of 2.0QO. and less uniform than in the previous example; the average transmittance is only 60 percent with a transmittance interval of t "5 percent, which is not acceptable for architectural use. The resulting coating is thinner. 7 As a third experiment, the starting flow method is repeated with a Reynolds number of 7,000. The resulting coating is of excellent quality as in Example III.

Finally, two experiments are performed with starting flow showing a Reynolds number of 5,000. In one experiment, the distance is nozzle--

Claims (2)

1. 0 15 7316813-0 23 substrate 0.9 times the nozzle width and in the second experiment the distance is 5 times the nozzle width. The resulting coating is in both cases sufficient to give a total average transmittance lower than 50 percent, but the variation in both cases is about É 3 percent indicative marginal quality for many architectural applications. In the case where the distance ratio is 0.9, the coating has a coarse grain structure approaching that encountered in spray application of similar coatings. EXAMPLE V The experiments according to Example III are repeated except that the nozzle according to the invention is replaced by an opening with flat walls having the same inlet and outlet cross-sectional area as the nozzle according to Example III. The resulting coatings are much thinner than those obtained in Example III. In addition, the coatings obtained show irregular transmittance, which can be visually observed. A method of applying a coating to a surface of a substrate (II), characterized in that: a gaseous mixture comprising at least one coating reactant is passed through a nozzle (45) (i) with an inlet end and a outlet end, the cross-section of which (a) is smaller than the cross-section (c) of the inlet end, and (ii) viewed at the opening of the outlet end, with a first pair of opposite inner sides and a second pair of opposite inner sides, the first pair of sides having a length which is greater than the length of the second pair of sides, so that the nozzle has an elongated cross-section, and wherein at least the first pair of inner sides has increasing radius of curvature from the inlet end opening to the outlet end opening to accelerate the flow of the gaseous mixture adjacent the nozzle surfaces, and directs the gaseous mixture towards the surface of the substrate to be coated, whereby said fl ïta is coated. 2. A method according to claim 1, characterized in that the gaseous mixture is passed through a nozzle, wherein the increasing radius of curvature of at least the first pair of inner sides increases constantly and uniformly from the opening of the inlet end to the opening of the outlet end. . 5. A method according to claim 2, characterized in that the linear velocity of the gaseous mixture through the nozzle increases uniformly from the opening of the inlet end to the opening of the outlet end. -4. Method according to claim 2, characterized in that the ratio between the area of the flow of gaseous mixture at the opening of the inlet end and the area of the flow of gaseous mixture at the opening of the outlet end is greater than about 4.5. A process according to claim 1, characterized by evaporating the coating reactant and mixing coating reactant vapors and a carrier gas to form said gaseous mixture and passing the gaseous mixture through the nozzle at a Reynolds number at the outlet end of at least about 2500. A process according to claim 5, characterized in that the gaseous mixture comprises vapors of reactive metal compound and a carrier gas, which comprises at least one reactant which reacts with said metal compound under the conditions prevailing next to the substrate. 7. A method according to claim 5, characterized in that the gaseous mixture directed from the nozzle wets substantially all the inner surfaces of the nozzle while the surfaces of the nozzle facing the substrate are not substantially wetted by the gaseous mixture . A method according to claim 5, characterized in that the gaseous mixture is passed through the nozzle at a Reynolds number of at least about 5000.. 9. A method according to claim 5, characterized in that the gaseous mixture, which is passed through the nozzle, has a substantially greater linear velocity at the nozzle outlet facing the substrate than at the inlet of the nozzle. 10. A method according to claim 5, characterized in that the nozzle has an elongate outlet end with a larger dimension and a smaller dimension and that the gaseous mixture flows from the nozzle outlet at a distance of at least 0.5 x the smaller dimension of the nozzle outlet, before it hits the ground. 7316813-0 25 ll. A method according to claim 10, characterized in that the gaseous mixture flows from the nozzle outlet at a distance of from about 1.25 to about 5 times the smaller dimension of the nozzle outlet, before it hits the substrate. Process according to Claim 5, characterized in that the temperature of the gaseous mixture at the nozzle outlet exceeds the temperature at which the metal reactant saturates the gaseous mixture, and in that the temperature of the gaseous mixture at the nozzle outlet is lower than the temperature at which The metal reactant reacts to form a coating material. A method according to claim 5, characterized in that the substrate is a glass strip moving in the downstream direction from the outlet end of a bath (47) in a float tank into a cooling furnace (55) and that the gaseous mixture is passed through the nozzle upstream of the cooling furnace and downstream of the outlet end of the bath. A method according to claim 15, characterized in that the nozzle has an elongate outlet end with a larger dimension and a smaller dimension and that the gaseous mixture flows from the nozzle outlet a distance of from about 0.5 to about 10 times the smaller dimension of the nozzle outlet before it hits the glass strip for coating the same. Apparatus for carrying out the method according to claim 1 for applying a coating to a surface of a substrate (II), characterized in that it comprises: "a. means for supporting a substrate, b. means (12 ) for vaporizing at least one coating reactant, c. means (13) for delivering the vaporized coating reactant to the substrate over an elongate area transverse to the substrate, the delivery means comprising a nozzle (43) having an inlet end and an outlet end. flue end, the cross section (a) of which is smaller than the cross section (c) of the inlet end and, viewed at the opening of the outlet end, having a first pair of opposite inner sides and a second pair of opposite inner sides, the first pair of sides having a length greater than the length of the second pair of sides, so that the nozzle has an elongate cross-section, and wherein at least the first pair of inner sides has an increasing radius of curvature from the opening of the inlet end to the opening of the outlet end to the flow of the gaseous mixture shall be accelerated adjacent to the inner surfaces of the nozzle. * fav at least about H3 * 7316813-0 26 16. Apparatus according to claim 15, characterized in that the nozzle has a contraction ratio (c / a) inlet to outlet 17. Apparatus according to claim 16, characterized in that the nozzle has a contraction ratio of at least about 6. Apparatus according to claim 15, characterized in that the radius of curvature of all nozzle walls facing each other increases uniformly from the inlet of the nozzle to its outlet. Apparatus according to claim 15, characterized in that it comprises a closed chamber (14) with inlet means (15 and 16, respectively) for receiving the evaporable coating reactant and a gaseous carrier for mixing the coating reactant with the gaseous carrier. , so that a gaseous mixture is formed at a first pressure, and conduit means (34) which connect the chamber to the nozzle and which are intended to distribute the gaseous mixture to the nozzle, and that the nozzle at its inlet is connected to the conduit means for directing the gaseous the mixture to the substrate at a second pressure which is lower than the first pressure, the nozzle having such inlet and outlet flow surfaces that the gaseous mixture has a Reynolds number at the outlet of at least about_§§QQ_when it leaves the closed the chamber at the first pressure. 20. An apparatus according to claim 19, characterized in that the means for supporting the substrate is arranged to transport said substrate in a path which is substantially transverse in relation to the larger dimension of the elongate nozzle. 21. An apparatus according to claim 19, characterized in that the surfaces of the nozzle adjacent to the inner surfaces of the nozzle at the outlet of the nozzle form an angle of less than about 900 with the adjacent inner surfaces. Apparatus according to claim 21, characterized in that the angle is about 870. Apparatus according to claim 19, it comprises means for setting the nozzle outlet at a distance from the facing surface of the substrate of at least 0.5 times characterized of that the smaller dimension of the nozzle outlet. Apparatus according to claim 23, characterized in that the distance between the nozzle outlet and the substrate is from about 1.25 to about 5 times the smaller dimension of the nozzle outlet. Apparatus according to claim 19, characterized in that the means for supporting the substrate is arranged in close proximity to the nozzle outlet, so that the center line of the gas flow from the nozzle outlet is substantially perpendicular to the main plane of a supported substrate and the distance from the nozzle outlet to the opposite face of the supported substrate is at least about 0.5 times the smaller dimension of the nozzle outlet. Apparatus according to claim 25, characterized in that the distance between the nozzle outlet and the substrate is from about 0.65 to about 5 times the smaller dimension of the nozzle outlet. Apparatus according to claim 25, characterized in that the distance between the nozzle outlet and the substrate is from about 1.25 to fi about 5 times the smaller dimension of the nozzle outlet. Apparatus according to claim 25, characterized in that the means for supporting the substrate comprises means for transporting the substrate past the nozzle with (i) the larger dimension of the nozzle outlet substantially perpendicular to the transport direction of the substrate, (ii) the projection of the larger dimension of the nozzle on a plane perpendicular to both the substrate and the transport direction of the substrate and (iii) the larger dimension of the nozzle is less than the width of the substrate perpendicular to the direction of movement of the substrate. Apparatus according to claim 25, characterized in that the distance between the nozzle outlet and the substrate is from about 1.25 to about 5 times the smaller dimension of the nozzle outlet and that the combination is provided with means for distributing the gaseous mixture substantially homogeneously. to the nozzle along its larger dimension. Apparatus according to claim 25, characterized in that the nozzle is provided with means for maintaining the temperature of the gaseous mixture flowing therethrough. 31. Apparatus according to claim 28, characterized in that the transport means are arranged between an outlet end of a forming chamber and an inlet end of a cooling chamber. An apparatus according to claim 19, characterized in that the nozzle has such inlet and outlet flow surfaces that the gaseous mixture has a Reynolds number of about 5000. PRESENTED PUBLICATIONS: US 2,704,728 (117-5Û); 3 282 243 (118 ~ 49), 3 438 803 (117-106)