CA1205994A - Foam generating nozzle - Google Patents
Foam generating nozzleInfo
- Publication number
- CA1205994A CA1205994A CA000439180A CA439180A CA1205994A CA 1205994 A CA1205994 A CA 1205994A CA 000439180 A CA000439180 A CA 000439180A CA 439180 A CA439180 A CA 439180A CA 1205994 A CA1205994 A CA 1205994A
- Authority
- CA
- Canada
- Prior art keywords
- solution
- chamber
- foam
- liquid
- gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
- B05B7/02—Spray pistols; Apparatus for discharge
- B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
- B05B7/0807—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets
- B05B7/0815—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets with at least one gas jet intersecting a jet constituted by a liquid or a mixture containing a liquid for controlling the shape of the latter
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/74—Mixing; Kneading using other mixers or combinations of mixers, e.g. of dissimilar mixers ; Plant
- B29B7/7438—Mixing guns, i.e. hand-held mixing units having dispensing means
- B29B7/7452—Mixing guns, i.e. hand-held mixing units having dispensing means for mixing components by spraying them into each other; for mixing by intersecting sheets
Abstract
FOAM GENERATING NOZZLE
Abstract of the Invention A foam generating nozzle is provided for converting a liquid containing a gas maintained under pressure in solution in the liquid, to a foam for application to a substrate.
Complete foaming of the solution is accomplished prior to discharge from the nozzle. This assures in some applications complete atomization before contact with the substance to be coated.
Abstract of the Invention A foam generating nozzle is provided for converting a liquid containing a gas maintained under pressure in solution in the liquid, to a foam for application to a substrate.
Complete foaming of the solution is accomplished prior to discharge from the nozzle. This assures in some applications complete atomization before contact with the substance to be coated.
Description
~- ~
~2~g~
Field of the Inven-tlon 'rhis invention relates generally to coating and finishing equipment and, more particularly, to an improved foam generating no~zle used in the application of film~orming solids includlng high ~olidg compo~itions.
L~LrgU~d ~f~ the Invention The problems associated with techniques known in the coating and finishing industry for the application of a coating to a substrate have been de~ailed in U.S. Patent No.
4,247,581 to Cobbs, Jr., et al~ Reference ~o such patent should be made for a detailed treatment of that subject, but it may be briefly stated for purposes of the present invention that the coating and finishing industry, despite extensive research and development effort, remains predominantly dependent on the use of ~vlve~t-containing coatings. It has been suggested that possibly the most serious concern of the industry today, considering both raw material usage and problems with envisonmental e~ects, concerns the solvent components of paint. In a spray co~ting application of a resinou6 material~ th~ resinous material i5 typically dissolved in an organic solvent to provide a viscosity suitable for spraying. This i5 required because it has been found that at each stage of the process for atomizing and conveying a resinous material in liquid form to a substrate, the liquid resists high speed deformation. Organic solvents are added to the resinous liquid because they have the effect of separating ~he molecules of resinous material and facilitating their relative movement making the solution more deformable at high speeds and therefore more susceptible to atomi~ation~
_~_ ~Z~S~94~
While a qreat deal of ef~ort ha~ be~n expended to reduce the volume of liquid solvent components in preparing high solids coating compositions containing above 50% by volume of polymeric and pigmentary solids, little success has been achieved. Most high solids coating compositions still contain from 15-40~ by volume of liquid solvent components.
The problem with such a high volume content of liquid solvents is that duxing handling, atomization or deposition of solvent coating compo~ltion~, the solvents will escape and can become alr contaminants if not properly ~rapped. Moreover, once a solvent coating is applied to a substrate the solvents are susceptible to escape fxom the film by evaporation and such evaporated solvents also contaminate the surrounding atmosphere. In addition, since most solvents react with oxidants, polluti~n problems of toxicity, odor and smog may also be created. Generally, attempts at overcoming such environmental problems are costly and relatively inefficient.
The invention disclosed in the 'S81 patent mentioned above is a method and apparatus ~or atomizing and conveylng high solids paint or other film formlng solids to a substrate for coating. In accordance with the method disclosed in the '581 patent, polymeric compositions having little or no solvent content and viscosities in the range o 300-30,800 centipoises are firs~ foamed to a relatively stable energized state and thereafter subjected to an atomizing force for uniform coating of a substxate. An important element of the '581 invention is the recognition that the use of an energized, relatively s able foam in coa ng applications eliminates many of the major problems existing in the finishing and coating industry including a drastic r~duction or elimination of the use of organic solvents. In contrast to conventional spraying or coating systems wherein foam was suppress~d during the manufacture, pigmenting, tinting, and application of paint or coating materials to a substrate, it was found as disclosed in the '581 patent that an exceptional surface coating could be achieved by first converting a film forming solid into a ~, foamed state and then disintegrating or atomizing the foam using known techniqu~s.
~ Given the teachings of the '581 patent that it is ,~ desirable to convert high solid paint or other film forming solids to a foam prior to atomi~ation and conveyance to a substrate, it should be stated that there are basically two ! generally used techniques to convert a liquid into a foam material. As discussed in U~S. Patent No. 4,059,714 to Scholl, et al, for example, one m~thod o producing a foam materlal from li~uid involves the injection of air or a gas such as nitrogen into the liquid under a suitable pressure.
The gas is forc~d into solution wi-th th~ liquid ~nd wh~n the liquid-gas ~olution i~ sub~quently di~pen~d into atmospheric pressure, the gas comes out o~ solution and ;, beco~es entrapped in the liquid to form a closed cell solid foam. The gas es~entially evolves from ~he solution under a~mospheric pressure in the form of small bubbles, cau~ing the surrounding liquid to expand volumetrically. The result is a homogeneous solid foam having closed air or gas cells evenly distributed throughout. In the alternative, as , disclosed for example in the '581 patent discussed above, a ; 30 so-called blowing agent may be placed into solution with a ~, r ~l ~ o ~
~2~ 4 I liquid under appropriate temperature and p~essure condikions. ~hen the soluti~n is ~xposed ~o a pr~ssure les3 than that required to maintain the blowing agent in i solution, gas bubbles ar~ produced and trapp~d in the liquid, forming a closed cell solid foam.
1 Several parameters must be observed in the process of creating and/or atomizing the foam to achieve an even coating of high solids paint or a similar ilm forming t material such as hot melt adhesives on a ~ubstrate. The ~ubject invention i9 primarily directed to improvements $n : the noæzles utilized to generate and atomi~e the closed cell solid foam. The problem is one of creating a ~table, low density foam which can be atomized prior to contact with the sub~trate. It was found using conven~ional paint or fluid nozzles that the point of formation of the high solids paint foam could not be adequately controlled. As mentioned above, whether a pressuriæed gas or a blowing agent is introduced into solution with a li~uid to be foamed, the foaming will not occur until the solution is exposed ~o a pressure less than the maintenance pre3sure of the solution.
Experiments with conventional fluid nozzles have shown that foaming of a solution containing high solids paint often occurred several inches from the end of the nozzle. As is well known, air jets or similar means are typically disposed immediately adjacent the end of foam nozzles to disintegrate or atomize the foam prior to contact with the substrate.
This assures even coating of the substrate. It can be appreciated that if foaming does not occur immediately at the point of exit from the nozzle, then complete atomization of the foam is impossible. The result is uneven coating of z~sg~
- the substrate. It can be appreciated that ~f foaming does no-t occur immedia-tely at the point of exit from the nozzle, then complete atomization of the foam i5 impossible. The result is uneven coating of the substrate, running or dripping of the paint and similar problems.
In addition to -the problem of forming the foam at the proper time, prior art foam nozzles tend Ito cause sputtering or non-uniform flow of the stream of foam formed from a high solids coating or similar material. It has been found that such a problem creates the same undesirable results as incomplate atomization of the foam discussed above.
I-t is therefore an objective of this invention -to provide a nozzle assembly for converting a liquid containing gas maintained under pressure in the liquid to a foam for application to a substrate.
; It is another object herein to provide a nozzle assembly capable of producing complete foaming of a solution containing a liquid and a gas maintained under pressure in the liquid, prior to the discharge of the liquid from the noæzle assembly, to assure complete àtomization upon dis-charge.
Summary of the Invention The invention herein which achieves these object-ives comprises a foam generating nozzle construction in which foaming of high solids paint or other relatively high density film forming solids such as adhesives is accom-pllshed prior to the point at which the paint exits the nozzle. A plug is disposed at one end of a foaming chamber and a discharge orifice is disposed at the other end of the chamber. A passage is formed in the plug, having a cross-sectional area at least as small as the cross~sectional area of the X
lcm/KH -6--- ~ -~ 4 discharge orifice and preferably five to ten times smaller than that of the discharge orifice.
A solution of high solids paint, for example, and air or a blowing agent, under pressure, is introduced into a high pressure chamber dlsposed on the other sidé of -the plug from the foaming chamber. The cross-sectional area of the discharge orifice is sufficiently large to introduce air withln the foaming chamber at a pres~ure approach~ng atmospheric. In a pre~erred embodiment of this invention, the pa~age is formed in the plug at an included angle of approximately 30, plus or minus 10~, measured relative to the longitudinal axis of the plug ox the side walls of the chamber, so that the pressurized solution of high solids paint and gas or a blowing agent will flow through the pas~age and impact again~-t the side-walls o~
tha foamlng chambe~ at such angla. In combination with the reduced pre~sure existing in the foaming chamber, the impacting of the pressurized solution against the foaming chamber's ~ide walls at such angle induces air bubbles to come out of ~olution to orm a closed-cell solid foam. Upon exiting the foaming chamber through th~ discharge orifice, the high solids paint foam iB atomized u~ing convention~l mean~ a~ discussed in detail below.
In other embodiments of this lnvention, it will b~
shown that the angle at which the solution of high solids palnt and air or a blowing agen~ impacts against the side walls of the foaming chamber may be essentially duplicated by other means, In particular, a sphere may be disposed in the foaming cha~ber immediately adjacent the outlet of the passage such that the pre urized solution impacts the ~ ,,, ;.~ .1 1 .`:
~(?59~
foaMlng chamb~r~ In ~he alternative, a wire or simllar obs~ructlon may ~e disposed Wi`t}lill the foamlncl chamber at ~n angle relative to the passage to accomplish the s~me angled impacting of the pressurized solu~ion as it enters the foaming chamber.
In summary of the above, therefore, the present invention provides a nozzle assembly for conver-ting a liquid/
gas solution into a foam, the gas being maintained under pressure in solution in the liquid, the nozzle assembly comprising: chamber means including an obstruction for - receiving the liquid/gas solution and causing the gas to leave solution and form a foam, the chamber means having a pressure lower than that required to maintain the ~as in solution in the liquid; a discharge oriice communicating with the chamber means; delivery means includlng an inlet passageway communicating with the chamber ~eans for directing the liquid/gas solution to the chamber means while maintaining the gas in soluti.on; the inlet passageway directing the liquid/gas solution into the chamber means and into engagement with the obstruction to agitate the liquid/gas solution, the agitation of the liquid/gas solution within the chamber means inducing the gas to leave solution and form a foam within the chamber means, the foam thereafter being emitted from the chamber means through the discharge orifice.
The present invention also may be considered as providing a method for converting a liquid containing a gas maintained under pressure in solution in the liquid to a foam for application to a substrate comprising the steps of conveying the solution to a chamber having a pressure lower than the pressure required to maintain the gas in solution in the liquid; releasing the solution w.ithin the chamber to form a foam; and discharging the foarn from the chamber sd/`- -8--` lZ~?S~4 for ~pplication to a substrate.
In one aspect o~ ~he invention, the nozzle assembly is disclosed for con~Terting a pressurized liquid/yas solution into foam ~hich includes a chamber having an obstruction therein. The pressurized liquid/gas solution enters the chamber and impacts the obstruction which, combined with a lowering of the pressure, causes a disturbance to the solution which results in a~ least partial foaming oE the solution ~efore it exits the nozzle assembly.
Descript~on of the Drawings The structure, operation and advantages of the foam generating nozzle herein will become apparen~ upon consideration of the following discussion taken in conjunction with the accompanying drawings, wherein:
Figure 1 is a side view in partial cross section of a spray gun incorporating the foam generating nozzle o~
this invention.
Fig~re 2 is an enlarged view of the foam generating nozzle portion of the spray gun shown in Figure 1.
Figure 3 is a cross-sectional view taken generally along line 3-3 of Figure 2.
Figure 4 is an alternate embodiment of the foam generating nozzle herein.
Figure 5 is a still further embodiment of the foam generatiny nozzle of this invention~
Detailed Description of the Invention -The spray gun labeled generally with the reference 11 in the drawings is a modification of that disclosed in U.S. Patent No. 4,241~880, which is assigned to the same assiynee as the present invention. Spray gun 11 generally includes a handle assembly 13, a harrel assembly 15 and nozzle assembly 17 which incorporate two distinct delivery sd/`~- _9 5i9941 systems; one for the conveyance of pressurized air to the nozzle of the gun 11, and a second for the conveyance of a liquid solution consisting of a film-forming solid and a blowing agent to the nozzle.
Referring now to Figures 1 and 2, the system for conveying a pressurized liquid solution through gun 11 will be considered first. As mentioned above, and discussed in detail in the '581 patent to Cobbs, Jr., et al, the initial step in the creating of a high solids foam is the formation of a pressurized solution consisting of either a blowing agent or gas and a high viscosity paint or other film-formlng solid. The '581 patent may be referred to for details of the formation of the solution. For purposes of the present discussion, the solution will be considered to include a film-forming solid such as paint or a hot melt adhesive and a blowing agent The pressurized solution is introduced into gun 11 through a hose lg connected to one side of a lug 21 attached to the lower end of the handle assembly 13. The lug 21 includ~s a fluid passage so as to convey the solution from hose 13 into a second hose 23 which is connected at the other end of lug 21. The second hose 23 extends from lu~ 21 and is connected at its other end to the barrel assembly 15 of gun 11 through a threaded inlet port 25 which communicates with an inlet passage 27. In turn, inlet passage 27 communicates with the rearward end of a central, annular passage 29 which extends axially along the barrel .~, ~-` ~ - i ~Z~`5~
~: assembly 21 and forwardly to the nozzle ~ssem~ly 17 of gun 1~ 11.
Axially disposed within the annular passage 29 is a control rod 31 which governs the flow of solution to the nozzle assembly 17. The con~rol rod 31 is mounted at its rearward end in ~ Dclrin packing nut 33 and exten~
outwardly therefrom to a trigger 35 mounted to the barrel a~sembly 15 of yun 11. The trigger 35 is blased forwardly toward the nozzle assembly 17 of gun 11 by a spring 36 mounted ~etween the handle assembly 13 and trigger 35. A
flexible bellows ~eal 37 is disposad along a portion of control rod 31 such as described in detail in ~.S. Patent No. 4,079,894 assigned to the assignee of this invention.
The trigger 35 is operable to axially reciprocate oontrol rod 31 within annular passage 29.
The forward end of control rod 31 terminates in a cone-shape tip 39 as shown in more detail in Figure 2. The cone-shape tip 39 o~ control rod 31 i~ engagable with a seat 41 to open and close the flow of solution from within the annular passage 29 to a high pressure chamb~r 43 disposed immediately forward of seat 41 toward the nozzle assembly 17. When the trigger 35 is pull~d rearwardly compressing spring 36, the control rod 31 is retracted thereby re~racting the cone-shape tip 39 from seat 41 allowing solution in annular passage 29 to enter the high pressure chamber 43~ When the trigger 35 is released, the spring 3Ç
urges control rod 31 forwardly so that its cone-shaped tip 39 engages seat 41 ~hereby isolating annular passage 29 from the high pressure chamber 43.
~, -10-;'`
., ~ ~ j 1 . , `! ~ i -\ o ~Z~5ig94 The ~olution of high solids paint and a blowing agent is conveyed from hose 13 and through gun 11 to the high pressure chamber 43 as discussed above. It should be understood that throughout the transfer of the solution along this path, ~h~ ~ioLution is mairltained at a ~r~s~ur~
above that of the so-called solution maintenance pressure or the pressure required to prevent the blowing agent from leaving solution and thus forming a foam. As discussed above, once the solution maintenance pressure is lowered, foaminq of the film forming solid will begin to occur. The problem to which this invention i9 directed involve~ the formation of ~uch foam at the desired poink in no~zle aS~2mbly 17 80 that problems of sputtering and ~ncomple~e atomization may ~e overcome.
Nozzle assembly 17 further includes a discharge orifice 45 through which tha foamed solution is emitted, as discussed below, and a plug 47 which ~ogether define the boundries of a foamin~ chamber 49~ The plug 47 is dispoqed ak one end of foaming chamber 49 immediately adjacent high pressure chamber 43. In one embodiment of the subject invention, a passage 51 i~ formed in plug 47 and is disposed at an acute angle relative to the sid~walls of foaming chamber 49 and the longitudinal axis of plu~ 47. As shown in Fiyura 3, plug 47 includes a slot 48 which can be rotat~d without effecting the position and angle of the passage 51, facilitating easy removal. The cross-sect.ional area of passage 51 is at least as small as the cross-sectional area of discharge orifice 45, and preerably from five to ten times or more smaller ~han the cross-sectional area of discharge orifice 45 in one embodiment. Oue to such size .
: -~LZ~99~
clifferential between discharge orific~ 45 and passage 51, the pressure within foaming chamber 49 is much le~s than that in high pressure chamber 43, and wel:L below the maintenance pressure of the solution. It has been found that as the solution is introduced through passage 51 and impacts against the side walls of foaming chamber 49, gas bubbles come out of solution ancl become entrapped in th~
high solids paint to form a closed-cell solid foam. The foam formed within chamber 49 is pushed toward the discharge oxifice 45 as additional solution released from high pressure chamber 43 enters foaming chamber 49, and such foam exiting through discharge orifice 45 is then atomized by known means as described in more detail below.
Experimentation has shown that easily atomized, low density foam can be produced in foaming chamber 49 only ~f variou~ parameters are met. It has bean obsexved that to achieve complete foaming of the high solid~ paint or other film forming solid within foaming chambex 49, the cross-sectional area of the passage 51 must be at least as ~0 small as the cross-sectional area of discharge orifice 45 and preferably between five and ten times or more smaller than orifice 45. In one experiment, a passage 51 having an internal diameter of .028" was utilized with a discharge orifice 45 having an internal diamter of .082l'. In terms of cross-sectional area, this meant that the discharge orifice 45 was approximately eight and one-half times as large as that of the passage Sl. Experiments c,onductecl using this relationship indicated that a low clensity foam was produced within foaming chamber 49 which was easily atomized. Tests conducted w e the disc a ge orifice 45 nd passege 51 wer - ~ -~Z~S99~
more nearly equal in cross-sectional area produced foam within foaming chamber 49 having a higher density making it difficult to break up through atomization when released from discharge orifice 45.
In addition, it is preferred to subject the solution flowing from high pressure chamber 43 through passage 51 to some form of obstruction within the foaming charnber 49. In the preferred embodiment of this invention shown in Figure 2, the passage 51 is formed in plug 47 at an angle A of about 30, plus or minus 10, with respect to the longitudinal axis of the plug 47 and the walls of foaming chamber 49. It has been found that by using some form of obstruction means which the stream of solution impacts at such an acute angle, foaming of the high solids paint will occur within foaming chamber 49 before being emitted from the discharge orifice 45. In Figure 2, the obstruction means is defined by the walls of oaming chamber 49.
Figures ~ and 5 show alternativs~ to the obstruction means of Fi~ure 2 in which the pl~g 47 is eliminated and solution flows from annular passage 29 to a constructed passage 54 formed at the rearward end of seat 41~ In Figure 4, a flat plane 53 is disposed within foaming chamber 49 immediately adjacent the constricted passage 54 so that the solution exi~ing high pressure chamber 43 is deflected from flat plane 53 which is disposed at an angle of approximately 30, plus or minus 10 relative to the longitudinal axis of passage 54. In Figure 5 a sphere 55 is disposed immediately adjacent constricted passage 54 within foaming cnan~er 49 so that its center is offset relative to -the path of the solu~ion exiting release orifice 51. In ` ~ S99~
both embodiments shown in Fiyures 4 and 5 the constrict~d ,~ passage 54, and th~? flat plan~3 53 or ~pher~ 55 ob~;tructi~n i means, are pref~rably disposed at such an angle relative to one ano~her that the solu~ion is shocked or disturbed to an extent where optimum foaming is achieved.
The preferred angle of 30, plus or minus 10, at which the p~essurized solution contacts an obstruction means, avoids problems of sputtering and incomplete atomiæation which are possible with prior nozzle assemblies.
For example, existing nozzle assemblies generally include a single discharge ori~ice for the release of solution from the gun~ In such prior nozzles little or n~ foaming occurs within the nozzla itself but b~gins only after the solution is released from the discharge orifice into the atmosphera.
1 It can be appreciated that unless complete or nearly complete foaming occurs immediately ater emission of the solution from the spray gun, incomplete atomization can occur. In fact, it has been found that depending on the .~ flow rate, foaming o~ a solu~ion containln(J high solids paint and a blowing agent may not occur using conventional nozzle assemblies until the solution has moved several .. inches from the discharge orifice. It is apparent that ; atomi2ation means associated with those noz~le assemblies : are ineffective due to atomizing the ~olution prior to foaming. As discussed above r the spray gun 11 herein avoids this problem by assuring that foaming occurs within foaming chamber 49 prior to emission from the discharge orifice 45.
A further advantage of disposing the obs-truction means at an angle of 30, plus or minus 10, relative to the pafh of the solution is that proper shocking or agitation of , -14-,.
,`. ~2~5~34 ',.
I the solution is achieved, thus enhancing the evolution of ,- the proper density of bubbles which cau~a the surrounding ; liquid to expand volumetrically. I~ has been found that foaming is restricted where the obstruction means is dispo~ed at angles approaching 90 relativé to the pa~h of the solution, since the bubbles evolving from the solution r tend to be broken up. As a result, the extent of foaming i8 reduced making atomization dificult.
The importance of achieving production of foam i 1~ having a proper d~nYity at or immediat~ly adjacent the point of exit from discharge orifice 45 is apparent upon ., consideration o~ the system of spray gun 11 ~or delivering pressurized air to the nozzle assembly 19. A hose 61 is connected on one end to an air inlet 63 mounted in the but~
.~ of handle aBsembly 13. The other end of ho~e 61 is ; connec~ed to a source of pressurized air (not shown). Aix inlet 63 communicates with an air passage 65 which extends ~ upwardly through handle assembly 13 toward th~ nozzle,, assembly 17 where it separates into an upper and lower branch duct or conduit 67 and 69 r~sp~ctively. Upper branch conduit 67 extends forwardly in~o an annular air chamber 71, while the lower branch duct 69 communicates with a plurality of circum~erentially spaced axial passag~s 73 which extend linearly along the length of foaming chamber 49.
Nozzle assembly 17 further include an annular retaining ring 75 which is thr~aded over a correspondingly threaded section of barrel assembly 15 at one end. The , other end of annular retainin~ ring 75 includes a lip 76 over which an air cap 77 is disposed, wi~h the lip 76 ; 30 engaging a wall 79 in an annular groove Bl formed in the ~2~5~
outside surface of the air cap 77 such that the air cap 77 is securely retained and sealed against the escape of air to the atmosphere. The air cap 77 is formed with opposed air horns 83 each havin~ anyl~(l oponinCJs 85 whi~h kaee inwardly toward the discharge oriEice 4S. The openin~s 85 in air horns 83 communicate with the annular air chamber 71. In addition, a plurality o~ axial orifices 87 are formed in air cap 77 immediately adjacent and generally parallel to thc discharge orifice 45. Axial orifices 87 communicate with axial passages 73.
Pressurized air is thus conveyed through hose 61, air passage 65, upper and lower branch conduits 67 and 69 to the annular air chamber 71 and the axial passages 73. Air ~raveling through the axial passages 73 exits the nozzle asRembly 17 through axial orifices 87 which atomizes the oam emitted from discharge orifice 49. From annular alr chamber 71, ~he pressurized ai~ Xlows thr~ugh the openings 85 in opposed air horns 83 where it impinges agains~ the foam exiting discharge orifice ~9 and performs tha dual function of atomizing the foam and also shaping th~ pattern in which the foam is delivered to a subs~rate as it axits spray gun ll. As discussed above, the proximity of axial orifices 87 and openings 85 to the discharg~ orifice 45 require that foaming of the high solids paint be complete at or immediately adjacent discharge orifice 45. This is accomplished by the invention herein since foaming o the hi~h solids paint occurs within foaming chamber 49 and not exterior to t~le discharge orifice 45.
Although the invention has been described in terms of three different preferred embodiments, persons skilled in ,:
.
~s~4 Throughout this specification and claims the term"solution" has been used to describe the liquid gas dispersion supplied under high pressure to the gun, which dispersion when ¦ dispensed from the gun at atmospheric pressure cools and cr ates a coating. The applicants are of the view that this I mixture is a true solution in which the molecules of the dissolved gas are dispersed among those o~ the liquid. The l term though as used in the specification and the claims of the - ¦ application is intended to define and encompass the broader ¦ generic definition of solution which i5 a ga~ homogenously mixed with the liquid, whether or not the molecules o~ the dissolved gas are in fact dispersed among those of the solvent.
I Although the invention has been described in terms of ; three different preferred embodiments, persons skilled in thQ
art to which this invention pertains will readily appreciate other modi~ications and change~ which may ~e made without , departing from the spirit o~ the invention. Therefore, we do ! ~ not in~end to bs limited except by the scope o~ the appended ! claims.
~ Thus havinq described the inven~ion, what is claimed ~ is:
~2~g~
Field of the Inven-tlon 'rhis invention relates generally to coating and finishing equipment and, more particularly, to an improved foam generating no~zle used in the application of film~orming solids includlng high ~olidg compo~itions.
L~LrgU~d ~f~ the Invention The problems associated with techniques known in the coating and finishing industry for the application of a coating to a substrate have been de~ailed in U.S. Patent No.
4,247,581 to Cobbs, Jr., et al~ Reference ~o such patent should be made for a detailed treatment of that subject, but it may be briefly stated for purposes of the present invention that the coating and finishing industry, despite extensive research and development effort, remains predominantly dependent on the use of ~vlve~t-containing coatings. It has been suggested that possibly the most serious concern of the industry today, considering both raw material usage and problems with envisonmental e~ects, concerns the solvent components of paint. In a spray co~ting application of a resinou6 material~ th~ resinous material i5 typically dissolved in an organic solvent to provide a viscosity suitable for spraying. This i5 required because it has been found that at each stage of the process for atomizing and conveying a resinous material in liquid form to a substrate, the liquid resists high speed deformation. Organic solvents are added to the resinous liquid because they have the effect of separating ~he molecules of resinous material and facilitating their relative movement making the solution more deformable at high speeds and therefore more susceptible to atomi~ation~
_~_ ~Z~S~94~
While a qreat deal of ef~ort ha~ be~n expended to reduce the volume of liquid solvent components in preparing high solids coating compositions containing above 50% by volume of polymeric and pigmentary solids, little success has been achieved. Most high solids coating compositions still contain from 15-40~ by volume of liquid solvent components.
The problem with such a high volume content of liquid solvents is that duxing handling, atomization or deposition of solvent coating compo~ltion~, the solvents will escape and can become alr contaminants if not properly ~rapped. Moreover, once a solvent coating is applied to a substrate the solvents are susceptible to escape fxom the film by evaporation and such evaporated solvents also contaminate the surrounding atmosphere. In addition, since most solvents react with oxidants, polluti~n problems of toxicity, odor and smog may also be created. Generally, attempts at overcoming such environmental problems are costly and relatively inefficient.
The invention disclosed in the 'S81 patent mentioned above is a method and apparatus ~or atomizing and conveylng high solids paint or other film formlng solids to a substrate for coating. In accordance with the method disclosed in the '581 patent, polymeric compositions having little or no solvent content and viscosities in the range o 300-30,800 centipoises are firs~ foamed to a relatively stable energized state and thereafter subjected to an atomizing force for uniform coating of a substxate. An important element of the '581 invention is the recognition that the use of an energized, relatively s able foam in coa ng applications eliminates many of the major problems existing in the finishing and coating industry including a drastic r~duction or elimination of the use of organic solvents. In contrast to conventional spraying or coating systems wherein foam was suppress~d during the manufacture, pigmenting, tinting, and application of paint or coating materials to a substrate, it was found as disclosed in the '581 patent that an exceptional surface coating could be achieved by first converting a film forming solid into a ~, foamed state and then disintegrating or atomizing the foam using known techniqu~s.
~ Given the teachings of the '581 patent that it is ,~ desirable to convert high solid paint or other film forming solids to a foam prior to atomi~ation and conveyance to a substrate, it should be stated that there are basically two ! generally used techniques to convert a liquid into a foam material. As discussed in U~S. Patent No. 4,059,714 to Scholl, et al, for example, one m~thod o producing a foam materlal from li~uid involves the injection of air or a gas such as nitrogen into the liquid under a suitable pressure.
The gas is forc~d into solution wi-th th~ liquid ~nd wh~n the liquid-gas ~olution i~ sub~quently di~pen~d into atmospheric pressure, the gas comes out o~ solution and ;, beco~es entrapped in the liquid to form a closed cell solid foam. The gas es~entially evolves from ~he solution under a~mospheric pressure in the form of small bubbles, cau~ing the surrounding liquid to expand volumetrically. The result is a homogeneous solid foam having closed air or gas cells evenly distributed throughout. In the alternative, as , disclosed for example in the '581 patent discussed above, a ; 30 so-called blowing agent may be placed into solution with a ~, r ~l ~ o ~
~2~ 4 I liquid under appropriate temperature and p~essure condikions. ~hen the soluti~n is ~xposed ~o a pr~ssure les3 than that required to maintain the blowing agent in i solution, gas bubbles ar~ produced and trapp~d in the liquid, forming a closed cell solid foam.
1 Several parameters must be observed in the process of creating and/or atomizing the foam to achieve an even coating of high solids paint or a similar ilm forming t material such as hot melt adhesives on a ~ubstrate. The ~ubject invention i9 primarily directed to improvements $n : the noæzles utilized to generate and atomi~e the closed cell solid foam. The problem is one of creating a ~table, low density foam which can be atomized prior to contact with the sub~trate. It was found using conven~ional paint or fluid nozzles that the point of formation of the high solids paint foam could not be adequately controlled. As mentioned above, whether a pressuriæed gas or a blowing agent is introduced into solution with a li~uid to be foamed, the foaming will not occur until the solution is exposed ~o a pressure less than the maintenance pre3sure of the solution.
Experiments with conventional fluid nozzles have shown that foaming of a solution containing high solids paint often occurred several inches from the end of the nozzle. As is well known, air jets or similar means are typically disposed immediately adjacent the end of foam nozzles to disintegrate or atomize the foam prior to contact with the substrate.
This assures even coating of the substrate. It can be appreciated that if foaming does not occur immediately at the point of exit from the nozzle, then complete atomization of the foam is impossible. The result is uneven coating of z~sg~
- the substrate. It can be appreciated that ~f foaming does no-t occur immedia-tely at the point of exit from the nozzle, then complete atomization of the foam i5 impossible. The result is uneven coating of the substrate, running or dripping of the paint and similar problems.
In addition to -the problem of forming the foam at the proper time, prior art foam nozzles tend Ito cause sputtering or non-uniform flow of the stream of foam formed from a high solids coating or similar material. It has been found that such a problem creates the same undesirable results as incomplate atomization of the foam discussed above.
I-t is therefore an objective of this invention -to provide a nozzle assembly for converting a liquid containing gas maintained under pressure in the liquid to a foam for application to a substrate.
; It is another object herein to provide a nozzle assembly capable of producing complete foaming of a solution containing a liquid and a gas maintained under pressure in the liquid, prior to the discharge of the liquid from the noæzle assembly, to assure complete àtomization upon dis-charge.
Summary of the Invention The invention herein which achieves these object-ives comprises a foam generating nozzle construction in which foaming of high solids paint or other relatively high density film forming solids such as adhesives is accom-pllshed prior to the point at which the paint exits the nozzle. A plug is disposed at one end of a foaming chamber and a discharge orifice is disposed at the other end of the chamber. A passage is formed in the plug, having a cross-sectional area at least as small as the cross~sectional area of the X
lcm/KH -6--- ~ -~ 4 discharge orifice and preferably five to ten times smaller than that of the discharge orifice.
A solution of high solids paint, for example, and air or a blowing agent, under pressure, is introduced into a high pressure chamber dlsposed on the other sidé of -the plug from the foaming chamber. The cross-sectional area of the discharge orifice is sufficiently large to introduce air withln the foaming chamber at a pres~ure approach~ng atmospheric. In a pre~erred embodiment of this invention, the pa~age is formed in the plug at an included angle of approximately 30, plus or minus 10~, measured relative to the longitudinal axis of the plug ox the side walls of the chamber, so that the pressurized solution of high solids paint and gas or a blowing agent will flow through the pas~age and impact again~-t the side-walls o~
tha foamlng chambe~ at such angla. In combination with the reduced pre~sure existing in the foaming chamber, the impacting of the pressurized solution against the foaming chamber's ~ide walls at such angle induces air bubbles to come out of ~olution to orm a closed-cell solid foam. Upon exiting the foaming chamber through th~ discharge orifice, the high solids paint foam iB atomized u~ing convention~l mean~ a~ discussed in detail below.
In other embodiments of this lnvention, it will b~
shown that the angle at which the solution of high solids palnt and air or a blowing agen~ impacts against the side walls of the foaming chamber may be essentially duplicated by other means, In particular, a sphere may be disposed in the foaming cha~ber immediately adjacent the outlet of the passage such that the pre urized solution impacts the ~ ,,, ;.~ .1 1 .`:
~(?59~
foaMlng chamb~r~ In ~he alternative, a wire or simllar obs~ructlon may ~e disposed Wi`t}lill the foamlncl chamber at ~n angle relative to the passage to accomplish the s~me angled impacting of the pressurized solu~ion as it enters the foaming chamber.
In summary of the above, therefore, the present invention provides a nozzle assembly for conver-ting a liquid/
gas solution into a foam, the gas being maintained under pressure in solution in the liquid, the nozzle assembly comprising: chamber means including an obstruction for - receiving the liquid/gas solution and causing the gas to leave solution and form a foam, the chamber means having a pressure lower than that required to maintain the ~as in solution in the liquid; a discharge oriice communicating with the chamber means; delivery means includlng an inlet passageway communicating with the chamber ~eans for directing the liquid/gas solution to the chamber means while maintaining the gas in soluti.on; the inlet passageway directing the liquid/gas solution into the chamber means and into engagement with the obstruction to agitate the liquid/gas solution, the agitation of the liquid/gas solution within the chamber means inducing the gas to leave solution and form a foam within the chamber means, the foam thereafter being emitted from the chamber means through the discharge orifice.
The present invention also may be considered as providing a method for converting a liquid containing a gas maintained under pressure in solution in the liquid to a foam for application to a substrate comprising the steps of conveying the solution to a chamber having a pressure lower than the pressure required to maintain the gas in solution in the liquid; releasing the solution w.ithin the chamber to form a foam; and discharging the foarn from the chamber sd/`- -8--` lZ~?S~4 for ~pplication to a substrate.
In one aspect o~ ~he invention, the nozzle assembly is disclosed for con~Terting a pressurized liquid/yas solution into foam ~hich includes a chamber having an obstruction therein. The pressurized liquid/gas solution enters the chamber and impacts the obstruction which, combined with a lowering of the pressure, causes a disturbance to the solution which results in a~ least partial foaming oE the solution ~efore it exits the nozzle assembly.
Descript~on of the Drawings The structure, operation and advantages of the foam generating nozzle herein will become apparen~ upon consideration of the following discussion taken in conjunction with the accompanying drawings, wherein:
Figure 1 is a side view in partial cross section of a spray gun incorporating the foam generating nozzle o~
this invention.
Fig~re 2 is an enlarged view of the foam generating nozzle portion of the spray gun shown in Figure 1.
Figure 3 is a cross-sectional view taken generally along line 3-3 of Figure 2.
Figure 4 is an alternate embodiment of the foam generating nozzle herein.
Figure 5 is a still further embodiment of the foam generatiny nozzle of this invention~
Detailed Description of the Invention -The spray gun labeled generally with the reference 11 in the drawings is a modification of that disclosed in U.S. Patent No. 4,241~880, which is assigned to the same assiynee as the present invention. Spray gun 11 generally includes a handle assembly 13, a harrel assembly 15 and nozzle assembly 17 which incorporate two distinct delivery sd/`~- _9 5i9941 systems; one for the conveyance of pressurized air to the nozzle of the gun 11, and a second for the conveyance of a liquid solution consisting of a film-forming solid and a blowing agent to the nozzle.
Referring now to Figures 1 and 2, the system for conveying a pressurized liquid solution through gun 11 will be considered first. As mentioned above, and discussed in detail in the '581 patent to Cobbs, Jr., et al, the initial step in the creating of a high solids foam is the formation of a pressurized solution consisting of either a blowing agent or gas and a high viscosity paint or other film-formlng solid. The '581 patent may be referred to for details of the formation of the solution. For purposes of the present discussion, the solution will be considered to include a film-forming solid such as paint or a hot melt adhesive and a blowing agent The pressurized solution is introduced into gun 11 through a hose lg connected to one side of a lug 21 attached to the lower end of the handle assembly 13. The lug 21 includ~s a fluid passage so as to convey the solution from hose 13 into a second hose 23 which is connected at the other end of lug 21. The second hose 23 extends from lu~ 21 and is connected at its other end to the barrel assembly 15 of gun 11 through a threaded inlet port 25 which communicates with an inlet passage 27. In turn, inlet passage 27 communicates with the rearward end of a central, annular passage 29 which extends axially along the barrel .~, ~-` ~ - i ~Z~`5~
~: assembly 21 and forwardly to the nozzle ~ssem~ly 17 of gun 1~ 11.
Axially disposed within the annular passage 29 is a control rod 31 which governs the flow of solution to the nozzle assembly 17. The con~rol rod 31 is mounted at its rearward end in ~ Dclrin packing nut 33 and exten~
outwardly therefrom to a trigger 35 mounted to the barrel a~sembly 15 of yun 11. The trigger 35 is blased forwardly toward the nozzle assembly 17 of gun 11 by a spring 36 mounted ~etween the handle assembly 13 and trigger 35. A
flexible bellows ~eal 37 is disposad along a portion of control rod 31 such as described in detail in ~.S. Patent No. 4,079,894 assigned to the assignee of this invention.
The trigger 35 is operable to axially reciprocate oontrol rod 31 within annular passage 29.
The forward end of control rod 31 terminates in a cone-shape tip 39 as shown in more detail in Figure 2. The cone-shape tip 39 o~ control rod 31 i~ engagable with a seat 41 to open and close the flow of solution from within the annular passage 29 to a high pressure chamb~r 43 disposed immediately forward of seat 41 toward the nozzle assembly 17. When the trigger 35 is pull~d rearwardly compressing spring 36, the control rod 31 is retracted thereby re~racting the cone-shape tip 39 from seat 41 allowing solution in annular passage 29 to enter the high pressure chamber 43~ When the trigger 35 is released, the spring 3Ç
urges control rod 31 forwardly so that its cone-shaped tip 39 engages seat 41 ~hereby isolating annular passage 29 from the high pressure chamber 43.
~, -10-;'`
., ~ ~ j 1 . , `! ~ i -\ o ~Z~5ig94 The ~olution of high solids paint and a blowing agent is conveyed from hose 13 and through gun 11 to the high pressure chamber 43 as discussed above. It should be understood that throughout the transfer of the solution along this path, ~h~ ~ioLution is mairltained at a ~r~s~ur~
above that of the so-called solution maintenance pressure or the pressure required to prevent the blowing agent from leaving solution and thus forming a foam. As discussed above, once the solution maintenance pressure is lowered, foaminq of the film forming solid will begin to occur. The problem to which this invention i9 directed involve~ the formation of ~uch foam at the desired poink in no~zle aS~2mbly 17 80 that problems of sputtering and ~ncomple~e atomization may ~e overcome.
Nozzle assembly 17 further includes a discharge orifice 45 through which tha foamed solution is emitted, as discussed below, and a plug 47 which ~ogether define the boundries of a foamin~ chamber 49~ The plug 47 is dispoqed ak one end of foaming chamber 49 immediately adjacent high pressure chamber 43. In one embodiment of the subject invention, a passage 51 i~ formed in plug 47 and is disposed at an acute angle relative to the sid~walls of foaming chamber 49 and the longitudinal axis of plu~ 47. As shown in Fiyura 3, plug 47 includes a slot 48 which can be rotat~d without effecting the position and angle of the passage 51, facilitating easy removal. The cross-sect.ional area of passage 51 is at least as small as the cross-sectional area of discharge orifice 45, and preerably from five to ten times or more smaller ~han the cross-sectional area of discharge orifice 45 in one embodiment. Oue to such size .
: -~LZ~99~
clifferential between discharge orific~ 45 and passage 51, the pressure within foaming chamber 49 is much le~s than that in high pressure chamber 43, and wel:L below the maintenance pressure of the solution. It has been found that as the solution is introduced through passage 51 and impacts against the side walls of foaming chamber 49, gas bubbles come out of solution ancl become entrapped in th~
high solids paint to form a closed-cell solid foam. The foam formed within chamber 49 is pushed toward the discharge oxifice 45 as additional solution released from high pressure chamber 43 enters foaming chamber 49, and such foam exiting through discharge orifice 45 is then atomized by known means as described in more detail below.
Experimentation has shown that easily atomized, low density foam can be produced in foaming chamber 49 only ~f variou~ parameters are met. It has bean obsexved that to achieve complete foaming of the high solid~ paint or other film forming solid within foaming chambex 49, the cross-sectional area of the passage 51 must be at least as ~0 small as the cross-sectional area of discharge orifice 45 and preferably between five and ten times or more smaller than orifice 45. In one experiment, a passage 51 having an internal diameter of .028" was utilized with a discharge orifice 45 having an internal diamter of .082l'. In terms of cross-sectional area, this meant that the discharge orifice 45 was approximately eight and one-half times as large as that of the passage Sl. Experiments c,onductecl using this relationship indicated that a low clensity foam was produced within foaming chamber 49 which was easily atomized. Tests conducted w e the disc a ge orifice 45 nd passege 51 wer - ~ -~Z~S99~
more nearly equal in cross-sectional area produced foam within foaming chamber 49 having a higher density making it difficult to break up through atomization when released from discharge orifice 45.
In addition, it is preferred to subject the solution flowing from high pressure chamber 43 through passage 51 to some form of obstruction within the foaming charnber 49. In the preferred embodiment of this invention shown in Figure 2, the passage 51 is formed in plug 47 at an angle A of about 30, plus or minus 10, with respect to the longitudinal axis of the plug 47 and the walls of foaming chamber 49. It has been found that by using some form of obstruction means which the stream of solution impacts at such an acute angle, foaming of the high solids paint will occur within foaming chamber 49 before being emitted from the discharge orifice 45. In Figure 2, the obstruction means is defined by the walls of oaming chamber 49.
Figures ~ and 5 show alternativs~ to the obstruction means of Fi~ure 2 in which the pl~g 47 is eliminated and solution flows from annular passage 29 to a constructed passage 54 formed at the rearward end of seat 41~ In Figure 4, a flat plane 53 is disposed within foaming chamber 49 immediately adjacent the constricted passage 54 so that the solution exi~ing high pressure chamber 43 is deflected from flat plane 53 which is disposed at an angle of approximately 30, plus or minus 10 relative to the longitudinal axis of passage 54. In Figure 5 a sphere 55 is disposed immediately adjacent constricted passage 54 within foaming cnan~er 49 so that its center is offset relative to -the path of the solu~ion exiting release orifice 51. In ` ~ S99~
both embodiments shown in Fiyures 4 and 5 the constrict~d ,~ passage 54, and th~? flat plan~3 53 or ~pher~ 55 ob~;tructi~n i means, are pref~rably disposed at such an angle relative to one ano~her that the solu~ion is shocked or disturbed to an extent where optimum foaming is achieved.
The preferred angle of 30, plus or minus 10, at which the p~essurized solution contacts an obstruction means, avoids problems of sputtering and incomplete atomiæation which are possible with prior nozzle assemblies.
For example, existing nozzle assemblies generally include a single discharge ori~ice for the release of solution from the gun~ In such prior nozzles little or n~ foaming occurs within the nozzla itself but b~gins only after the solution is released from the discharge orifice into the atmosphera.
1 It can be appreciated that unless complete or nearly complete foaming occurs immediately ater emission of the solution from the spray gun, incomplete atomization can occur. In fact, it has been found that depending on the .~ flow rate, foaming o~ a solu~ion containln(J high solids paint and a blowing agent may not occur using conventional nozzle assemblies until the solution has moved several .. inches from the discharge orifice. It is apparent that ; atomi2ation means associated with those noz~le assemblies : are ineffective due to atomizing the ~olution prior to foaming. As discussed above r the spray gun 11 herein avoids this problem by assuring that foaming occurs within foaming chamber 49 prior to emission from the discharge orifice 45.
A further advantage of disposing the obs-truction means at an angle of 30, plus or minus 10, relative to the pafh of the solution is that proper shocking or agitation of , -14-,.
,`. ~2~5~34 ',.
I the solution is achieved, thus enhancing the evolution of ,- the proper density of bubbles which cau~a the surrounding ; liquid to expand volumetrically. I~ has been found that foaming is restricted where the obstruction means is dispo~ed at angles approaching 90 relativé to the pa~h of the solution, since the bubbles evolving from the solution r tend to be broken up. As a result, the extent of foaming i8 reduced making atomization dificult.
The importance of achieving production of foam i 1~ having a proper d~nYity at or immediat~ly adjacent the point of exit from discharge orifice 45 is apparent upon ., consideration o~ the system of spray gun 11 ~or delivering pressurized air to the nozzle assembly 19. A hose 61 is connected on one end to an air inlet 63 mounted in the but~
.~ of handle aBsembly 13. The other end of ho~e 61 is ; connec~ed to a source of pressurized air (not shown). Aix inlet 63 communicates with an air passage 65 which extends ~ upwardly through handle assembly 13 toward th~ nozzle,, assembly 17 where it separates into an upper and lower branch duct or conduit 67 and 69 r~sp~ctively. Upper branch conduit 67 extends forwardly in~o an annular air chamber 71, while the lower branch duct 69 communicates with a plurality of circum~erentially spaced axial passag~s 73 which extend linearly along the length of foaming chamber 49.
Nozzle assembly 17 further include an annular retaining ring 75 which is thr~aded over a correspondingly threaded section of barrel assembly 15 at one end. The , other end of annular retainin~ ring 75 includes a lip 76 over which an air cap 77 is disposed, wi~h the lip 76 ; 30 engaging a wall 79 in an annular groove Bl formed in the ~2~5~
outside surface of the air cap 77 such that the air cap 77 is securely retained and sealed against the escape of air to the atmosphere. The air cap 77 is formed with opposed air horns 83 each havin~ anyl~(l oponinCJs 85 whi~h kaee inwardly toward the discharge oriEice 4S. The openin~s 85 in air horns 83 communicate with the annular air chamber 71. In addition, a plurality o~ axial orifices 87 are formed in air cap 77 immediately adjacent and generally parallel to thc discharge orifice 45. Axial orifices 87 communicate with axial passages 73.
Pressurized air is thus conveyed through hose 61, air passage 65, upper and lower branch conduits 67 and 69 to the annular air chamber 71 and the axial passages 73. Air ~raveling through the axial passages 73 exits the nozzle asRembly 17 through axial orifices 87 which atomizes the oam emitted from discharge orifice 49. From annular alr chamber 71, ~he pressurized ai~ Xlows thr~ugh the openings 85 in opposed air horns 83 where it impinges agains~ the foam exiting discharge orifice ~9 and performs tha dual function of atomizing the foam and also shaping th~ pattern in which the foam is delivered to a subs~rate as it axits spray gun ll. As discussed above, the proximity of axial orifices 87 and openings 85 to the discharg~ orifice 45 require that foaming of the high solids paint be complete at or immediately adjacent discharge orifice 45. This is accomplished by the invention herein since foaming o the hi~h solids paint occurs within foaming chamber 49 and not exterior to t~le discharge orifice 45.
Although the invention has been described in terms of three different preferred embodiments, persons skilled in ,:
.
~s~4 Throughout this specification and claims the term"solution" has been used to describe the liquid gas dispersion supplied under high pressure to the gun, which dispersion when ¦ dispensed from the gun at atmospheric pressure cools and cr ates a coating. The applicants are of the view that this I mixture is a true solution in which the molecules of the dissolved gas are dispersed among those o~ the liquid. The l term though as used in the specification and the claims of the - ¦ application is intended to define and encompass the broader ¦ generic definition of solution which i5 a ga~ homogenously mixed with the liquid, whether or not the molecules o~ the dissolved gas are in fact dispersed among those of the solvent.
I Although the invention has been described in terms of ; three different preferred embodiments, persons skilled in thQ
art to which this invention pertains will readily appreciate other modi~ications and change~ which may ~e made without , departing from the spirit o~ the invention. Therefore, we do ! ~ not in~end to bs limited except by the scope o~ the appended ! claims.
~ Thus havinq described the inven~ion, what is claimed ~ is:
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A nozzle assembly for converting a liquid/gas solution into a foam, the gas being maintained under pressure in solution in the liquid, said nozzle assembly comprising:
chamber means including an obstruction for receiving the liquid-gas solution and causing the gas to leave solution and form a foam, said chamber means having a pressure lower than that required to maintain the gas in solution in the liquid;
a discharge orifice communicating with said chamber means;
delivery means including an inlet passageway communicating with said chamber means for directing the liquid/
gas solution to said chamber means while maintaining the gas in solution;
said inlet passageway directing the liquid/gas solution into said chamber means and into engagement with said obstruction to agitate the liquid/gas solution, the agitation of the liquid/gas solution within said chamber means inducing the gas to leave solution and form a foam within said chamber means, said foam thereafter being emitted from said chamber means through said discharge orifice.
chamber means including an obstruction for receiving the liquid-gas solution and causing the gas to leave solution and form a foam, said chamber means having a pressure lower than that required to maintain the gas in solution in the liquid;
a discharge orifice communicating with said chamber means;
delivery means including an inlet passageway communicating with said chamber means for directing the liquid/
gas solution to said chamber means while maintaining the gas in solution;
said inlet passageway directing the liquid/gas solution into said chamber means and into engagement with said obstruction to agitate the liquid/gas solution, the agitation of the liquid/gas solution within said chamber means inducing the gas to leave solution and form a foam within said chamber means, said foam thereafter being emitted from said chamber means through said discharge orifice.
2. The nozzle assembly of claim 1 further including means for atomizing said foam emitted from said discharge orifice.
3. The nozzle assembly of claim 1 in which the cross-sectional area of said discharge orifice is at least five times greater than the cross-sectional area of said inlet passageway.
4. The nozzle assembly of claim 1 further including a plug having a longitudinal axis, said inlet passageway being formed in said plug at an acute angle in the range of about 20°-40° relative to said longitudinal axis of the plug.
5. The nozzle assembly of claim 1 in which said chamber means includes an inner wall, said inlet passageway delivering the liquid/gas solution under pressure into engagement with said inner chamber wall, said inner chamber wall forming said obstruction to agitate the liquid/gas solution.
6. A method for converting a liquid containing a gas maintained under pressure in solution in said liquid to a foam for application to a substrate comprising the steps of:
conveying said solution to a chamber having a pressure lower than the pressure required to maintain said gas in solution in said liquid;
releasing said solution within said chamber to form a foam; and discharging said foam from said chamber for application to a substrate.
conveying said solution to a chamber having a pressure lower than the pressure required to maintain said gas in solution in said liquid;
releasing said solution within said chamber to form a foam; and discharging said foam from said chamber for application to a substrate.
7. A method for converting a liquid containing a gas maintained under pressure in solution in said liquid to a foam for application to a substrate comprising the steps of:
providing a nozzle assembly;
providing foaming means within said nozzle assembly, said foaming means including a chamber having a pressure lower than the pressure required to maintain said gas in solution in said liquid, and obstruction means disposed within said chamber;
conveying said solution to said chamber;
releasing said solution into said chamber and impacting said solution with said obstruction means to form said foam; and discharging said foam from said nozzle assembly.
providing a nozzle assembly;
providing foaming means within said nozzle assembly, said foaming means including a chamber having a pressure lower than the pressure required to maintain said gas in solution in said liquid, and obstruction means disposed within said chamber;
conveying said solution to said chamber;
releasing said solution into said chamber and impacting said solution with said obstruction means to form said foam; and discharging said foam from said nozzle assembly.
8. A method for converting a liquid containing a gas maintained under pressure in solution in said liquid to a foam for application to a substrate comprising the steps of:
providing a nozzle assembly;
providing foaming means within said nozzle assembly, said foaming means including a chamber having a pressure lower than the pressure required to maintain said gas in solution in said liquid, obstruction means disposed within said chamber, and plug means formed with a passage communicating with said chamber;
conveying said solution to said plug means;
releasing said solution through said passage into said chamber and into contact with said obstruction means to form said foam within said chamber; and discharging said foam from said nozzle assembly.
providing a nozzle assembly;
providing foaming means within said nozzle assembly, said foaming means including a chamber having a pressure lower than the pressure required to maintain said gas in solution in said liquid, obstruction means disposed within said chamber, and plug means formed with a passage communicating with said chamber;
conveying said solution to said plug means;
releasing said solution through said passage into said chamber and into contact with said obstruction means to form said foam within said chamber; and discharging said foam from said nozzle assembly.
9. A method for converting a liquid containing film-forming solids and a gas maintained under pressure in solution in said liquid to a foam for application of said film-forming solids to a substrate comprising the steps of:
providing a nozzle assembly;
providing foaming means within said nozzle assembly, said foaming means including a chamber having a pressure lower than the pressure required to maintain said gas in solution in said liquid, obstruction means disposed within said chamber, and plug means formed with a passage communicating with said chamber;
conveying said solution to said plug means;
releasing said solution through said passage into said chamber and into contact with said obstruction means to form said foam within said chamber;
discharging said foam from said nozzle assembly; and atomizing said foam.
providing a nozzle assembly;
providing foaming means within said nozzle assembly, said foaming means including a chamber having a pressure lower than the pressure required to maintain said gas in solution in said liquid, obstruction means disposed within said chamber, and plug means formed with a passage communicating with said chamber;
conveying said solution to said plug means;
releasing said solution through said passage into said chamber and into contact with said obstruction means to form said foam within said chamber;
discharging said foam from said nozzle assembly; and atomizing said foam.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/436,012 US4553701A (en) | 1982-10-22 | 1982-10-22 | Foam generating nozzle |
| US436,012 | 1982-10-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1205994A true CA1205994A (en) | 1986-06-17 |
Family
ID=23730741
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000439180A Expired CA1205994A (en) | 1982-10-22 | 1983-10-18 | Foam generating nozzle |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4553701A (en) |
| EP (1) | EP0107173B1 (en) |
| JP (1) | JPS59123547A (en) |
| CA (1) | CA1205994A (en) |
| DE (1) | DE3378894D1 (en) |
| ES (1) | ES8406227A1 (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE8434459U1 (en) * | 1984-11-24 | 1986-04-03 | Zeller Plastik Koehn, Graebner & Co, 5583 Zell | Foam generator |
| US4925101A (en) * | 1988-08-26 | 1990-05-15 | Nordson Corporation | Wax spray gun and nozzle |
| US4987854A (en) * | 1988-12-12 | 1991-01-29 | Nordson Corporation | Apparatus for gas-aided dispensing of liquid materials |
| US5114752A (en) * | 1988-12-12 | 1992-05-19 | Nordson Corporation | Method for gas-aided dispensing of liquid materials |
| US5159894A (en) * | 1989-08-04 | 1992-11-03 | Nordson Corporation | Apparatus for forming a permanent foam coating by atomization onto a substrate |
| US4983424A (en) * | 1989-08-04 | 1991-01-08 | Nordson Corporation | Method for forming a permanent foam coating by atomization onto a substrate |
| US5106659A (en) * | 1989-10-04 | 1992-04-21 | Nordson Corporation | Method and apparatus for spraying a liquid coating containing supercritical fluid or liquified gas |
| US5088443A (en) * | 1989-10-04 | 1992-02-18 | Nordson Corporation | Method and apparatus for spraying a liquid coating containing supercritical fluid or liquified gas |
| US5215253A (en) * | 1990-08-30 | 1993-06-01 | Nordson Corporation | Method and apparatus for forming and dispersing single and multiple phase coating material containing fluid diluent |
| US5197800A (en) * | 1991-06-28 | 1993-03-30 | Nordson Corporation | Method for forming coating material formulations substantially comprised of a saturated resin rich phase |
| US5354378A (en) * | 1992-07-08 | 1994-10-11 | Nordson Corporation | Slot nozzle apparatus for applying coatings to bottles |
| CA2098784A1 (en) * | 1992-07-08 | 1994-01-09 | Bentley Boger | Apparatus and methods for applying conformal coatings to electronic circuit boards |
| JPH07508923A (en) * | 1992-07-08 | 1995-10-05 | ノードソン コーポレーション | Apparatus and method for applying separate foam coatings |
| US5418009A (en) * | 1992-07-08 | 1995-05-23 | Nordson Corporation | Apparatus and methods for intermittently applying discrete adhesive coatings |
| US5421921A (en) * | 1992-07-08 | 1995-06-06 | Nordson Corporation | Segmented slot die for air spray of fibers |
| EP0579012B1 (en) * | 1992-07-08 | 1998-04-01 | Nordson Corporation | Apparatus and methods for applying discrete coatings |
| US5443796A (en) * | 1992-10-19 | 1995-08-22 | Nordson Corporation | Method and apparatus for preventing the formation of a solid precipitate in a coating material formulation |
| US5490726A (en) * | 1992-12-30 | 1996-02-13 | Nordson Corporation | Apparatus for proportioning two components to form a mixture |
| US5407267A (en) * | 1992-12-30 | 1995-04-18 | Nordson Corporation | Method and apparatus for forming and dispensing coating material containing multiple components |
| EP0974400B1 (en) | 1993-05-25 | 2002-08-07 | Nordson Corporation | Powder coating system |
| US5368233A (en) * | 1993-09-01 | 1994-11-29 | Nordson Corporation | Spray disk for close centerline spacing |
| US5407132A (en) * | 1993-10-20 | 1995-04-18 | Nordson Corporation | Method and apparatus for spraying viscous adhesives |
| US8814070B2 (en) * | 2010-10-20 | 2014-08-26 | Finishing Brands Holdings, Inc. | Fine finish airless spray tip assembly for a spray gun |
Family Cites Families (36)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US576762A (en) * | 1897-02-09 | Nozzle-valve | ||
| US604873A (en) * | 1898-05-31 | And roscoe bean | ||
| US587344A (en) * | 1897-08-03 | Hose-nozzle | ||
| US617472A (en) * | 1899-01-10 | And jonas | ||
| US614883A (en) * | 1898-11-29 | And jonas | ||
| US986201A (en) * | 1909-09-07 | 1911-03-07 | George F Nilsson | Lawn-sprinkler. |
| US1178905A (en) * | 1915-07-09 | 1916-04-11 | Edward F Cogley | Intensifier for spark-plugs. |
| US1886623A (en) * | 1931-07-22 | 1932-11-08 | Swartzbaugh Mfg Company | Liquid dispensing apparatus |
| US2161111A (en) * | 1935-05-25 | 1939-06-06 | Babcock & Wilcox Co | Spray nozzle |
| US2164411A (en) * | 1936-11-21 | 1939-07-04 | Kennedy Van Saun Mfg & Eng | Nozzle |
| US2231782A (en) * | 1939-07-17 | 1941-02-11 | Gertrude Phelps Thompson | Means for atomizing cleaning fluids |
| US2624622A (en) * | 1950-02-04 | 1953-01-06 | Pullman Sales Corp | Gun for delivering a detergent in foam form |
| US2760821A (en) * | 1954-04-05 | 1956-08-28 | Alfred L Kenworthy | Compound spray nozzles |
| US2764452A (en) * | 1954-06-28 | 1956-09-25 | Anderson Denton | Sprayer |
| US2955764A (en) * | 1958-01-24 | 1960-10-11 | Rain Jet Corp | Sprinkler |
| US3051397A (en) * | 1961-04-03 | 1962-08-28 | Grinnell Corp | Foam-water sprinkler device |
| US3446285A (en) * | 1967-08-07 | 1969-05-27 | Norman C Hout | Foam devices for fog nozzles |
| US3547200A (en) * | 1969-05-15 | 1970-12-15 | Norman C Hout | Foam device for fog nozzles |
| US3633795A (en) * | 1969-12-16 | 1972-01-11 | Insta Foam Prod Inc | Foam dispenser |
| US3625436A (en) * | 1969-12-19 | 1971-12-07 | Karl Heinz Wirths | Device for atomizing liquid |
| US3701482A (en) * | 1971-03-17 | 1972-10-31 | Norman H Sachnik | Foam generating nozzle |
| US3797747A (en) * | 1971-09-25 | 1974-03-19 | Hano Grohe Kg Fa | Device for aspirating and admixing additives into a stream |
| US3784111A (en) * | 1972-03-29 | 1974-01-08 | Spraying Systems Co | Foam producing nozzle |
| US3739989A (en) * | 1972-07-19 | 1973-06-19 | Coen Co | Duct burner for operation with liquid or gaseous fuels |
| US3836076A (en) * | 1972-10-10 | 1974-09-17 | Delavan Manufacturing Co | Foam generating nozzle |
| US3814329A (en) * | 1972-12-04 | 1974-06-04 | J Clark | Pressure reducing nozzles for pressure guns |
| US3946947A (en) * | 1973-09-11 | 1976-03-30 | Chemtrust Industries Corporation | Foam generating apparatus |
| US4103876A (en) * | 1975-04-30 | 1978-08-01 | Hasselman Jr Walter J | Method and apparatus for continuously producing and applying foam |
| US3961754A (en) * | 1975-09-12 | 1976-06-08 | Economics Laboratory, Inc. | Spray and foam producing nozzle apparatus |
| DE2619415C2 (en) * | 1976-05-03 | 1986-01-02 | Dietz-Armaturen Gmbh, 5060 Bergisch Gladbach | Dousing shower for generating a free-falling flat jet of liquid |
| US4059714A (en) * | 1976-08-02 | 1977-11-22 | Nordson Corporation | Hot melt thermoplastic adhesive foam system |
| US4247581A (en) * | 1977-10-14 | 1981-01-27 | Nordson Corporation | Method of coating with film-forming solids |
| US4241880A (en) * | 1979-03-16 | 1980-12-30 | Nordson Corporation | Electrostatic spray gun |
| DE7924574U1 (en) * | 1979-08-30 | 1979-11-29 | Brab, Hubert, Ing.(Grad.), 5100 Aachen | APPLICATION NOZZLE WITH VALVE |
| US4330086A (en) * | 1980-04-30 | 1982-05-18 | Duraclean International | Nozzle and method for generating foam |
| US4349156A (en) * | 1980-08-11 | 1982-09-14 | Spraying Systems Company | Efficiency nozzle |
-
1982
- 1982-10-22 US US06/436,012 patent/US4553701A/en not_active Expired - Fee Related
-
1983
- 1983-10-18 CA CA000439180A patent/CA1205994A/en not_active Expired
- 1983-10-19 EP EP83110398A patent/EP0107173B1/en not_active Expired
- 1983-10-19 DE DE8383110398T patent/DE3378894D1/en not_active Expired
- 1983-10-20 JP JP58195361A patent/JPS59123547A/en active Granted
- 1983-10-21 ES ES526668A patent/ES8406227A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0107173A3 (en) | 1985-11-21 |
| EP0107173B1 (en) | 1989-01-11 |
| JPH041666B2 (en) | 1992-01-13 |
| JPS59123547A (en) | 1984-07-17 |
| ES526668A0 (en) | 1984-08-01 |
| ES8406227A1 (en) | 1984-08-01 |
| EP0107173A2 (en) | 1984-05-02 |
| US4553701A (en) | 1985-11-19 |
| DE3378894D1 (en) | 1989-02-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1205994A (en) | Foam generating nozzle | |
| US4630774A (en) | Foam generating nozzle | |
| CA2047860C (en) | Plural component external mix spray gun and method | |
| US3734406A (en) | Method and apparatus for producing a flat fan paint spray pattern | |
| US3764069A (en) | Method and apparatus for spraying | |
| US4760956A (en) | Internal mix plural component system | |
| US3199790A (en) | Spraying apparatus for the production of foamed plastic materials for use as fillers and insulations | |
| US4927079A (en) | Plural component air spray gun and method | |
| EP0941144B1 (en) | A colliding stream spray dispensing system with a moldable nozzle | |
| US5074466A (en) | Fluid valve stem for air spray gun | |
| US3759450A (en) | Fluid mixing and spraying apparatus | |
| CA2318211A1 (en) | Modular system for atomizing a liquid and method of atomizing a liquid | |
| WO1992017279A1 (en) | Spray gun nozzle head | |
| KR860008803A (en) | Powder spraying apparatus and method | |
| JPS60232265A (en) | Air type spray nozzle device | |
| CA2163533A1 (en) | Spraying nozzle for regulating a rate of flow per unit of time | |
| CA2024657A1 (en) | Method and apparatus for spraying a liquid coating containing supercritical fluid or liquified gas | |
| US3923253A (en) | Spraying nozzle | |
| US4928884A (en) | Fluid assist airless spray nozzle | |
| US2895685A (en) | Spray nozzle | |
| ZA200600311B (en) | Method for producing a moulded article comprising a sprayed polyurethane layer | |
| KR100433299B1 (en) | Thermosetting plastic supply nozzle and method | |
| JP7343272B2 (en) | Spray nozzles with a pre-spray restrictor, spray heads and spray devices equipped with such nozzles | |
| HU189932B (en) | Nezzle for atomizing viscous fluids | |
| GB1350794A (en) | Mechanical nebulization device for the product stream from a pressurized dispenser |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |