HK1139356A - Spray gun - Google Patents

Description

Spray gun

Technical Field

The present invention relates to a method and apparatus for mixing a resin and a catalyst, and more particularly, to an apparatus for efficiently mixing a high viscosity densely packed resin with a catalyst and pressurized air, wherein the catalyst and pressurized air are mixed before being introduced into the resin.

Background

Resins have a variety of uses including, but not limited to, the construction of swimming pools, exterior coatings for buildings, protective interior coatings for tanks, and secondary containment wall coatings. Resins such as polyesters are typically applied to a surface with a catalyst such as methyl ethyl ketone peroxide. The catalyst allows the resin to polymerize and cure. In the prior art, the resin application method involves spraying the resin and methyl ethyl ketone peroxide onto a particular surface with a spray gun. Various spray guns are known in the prior art.

Internal mixing guns are often used when solvent injection is an issue because internal mixing limits the amount of atomized material and catalyst exiting the gun. Internal mixing guns typically have three feed lines, namely an air line and a resin line and a catalyst line feeding into a manifold. Typically the resin and catalyst are mixed within the manifold. After mixing, the resin and catalyst exit the gun through a nozzle or similar orifice in a combined state with pressurized air from the air line. The pressurized air provides sufficient pressure to cause the resin and catalyst to be sheared and atomized as they are discharged from the gun. The main disadvantage of such spray guns is that the catalyzed resin often flows back into and catalytically reacts with the air supply during the spraying operation. The catalyzed resin in the air supply device results in costly, time consuming downtime when the spraying operation is stopped and any obstructions to the air supply device are cleared. Standard check valves are rarely effective because they can be quickly closed by the hardening of the catalyzed resin or the inner working portion of the check valve can become blocked by the catalyzed resin. Another problem with such spray guns is that a portion of the catalyst supply line extends beyond the on/off valve (i.e. between the on/off valve and the manifold) so that when the device is shut off, some of the catalyst is discharged from the end of the supply line into the manifold, thus wasting catalyst.

The second type of gun typically used is an external mix gun. In the external mixing gun, the resin and the catalyst are atomized and discharged separately and directed toward each other, respectively. The resin and catalyst combine in air shortly before contacting the object to be treated. The main drawback of the external mixing gun is the incomplete mixing of the resin and the catalyst, which often results in pieces of incompletely catalyzed resin appearing on the finished product. This incompletely catalyzed resin fraction can create weak spots or blisters on the surface of the finished product.

A more important problem with external mixing guns is the external atomization of the catalyst. Because the catalyst is not completely mixed with the resin, a large portion of the atomized catalyst is dispersed into the atmosphere, and more specifically, into the immediate working environment in which the application is being performed. The use of these external mixing guns is subject to a number of limitations in view of the safety of the workers breathing air contaminated with catalyst. At least one state has completely prohibited the use of such guns.

Another gun is disclosed in U.S. patent nos. 5,388,767, 5,388,768, and 5,388,763. In the devices disclosed in these patents, the resin and catalyst are neither mixed in the manifold nor mixed after they are discharged. Rather, in these devices, the resin and catalyst are introduced separately into a mixing tube where they mix as they move toward the nozzle end of the mixing tube. Separately from the mixing tube, a flow of pressurized air is combined, which introduces pressurized air into the mixing tube. The pressurized air helps mix the catalyst and resin in the mixing tube and also helps to expel the catalyst/resin from the end of the mixing tube (the nozzle end). One problem with this design is that in order to prevent backflow of the resin into the catalyst supply line in the event of a blocked mixing tube, the catalyst must be introduced into the mixing tube at the same pressure as the resin, which can approach 3000 pounds per square inch (psi) depending on the viscosity of the resin. It is undesirable to introduce the catalyst at such high pressures, as the catalyst can often be aggressive and dangerous. If the catalyst lines break at high pressure, the catalyst can be sprayed out violently, and thus can cause serious damage to life and property. Another problem with the designs disclosed in these patents is that it can be difficult for the viscous resin to mix well with the watery catalyst as the catalyst and resin move through the mixing tube. In fact, a relatively high viscosity catalyst typically forms its own path as it moves through the mixing tube without completely mixing with the resin, thus resulting in incomplete mixing of the resin and catalyst.

The present invention substantially eliminates the difficulties encountered with the prior art as discussed herein above.

Disclosure of Invention

It is therefore an object of the present invention to provide a spray gun in which the catalyst is introduced into an air supply line and atomized in the air supply line prior to introduction into the resin, so that the pressure at which the catalyst is supplied to the system need only approximate the pressure at which air is supplied to the system.

It is another object of the present invention to provide a spray gun wherein the catalyst is introduced into an air supply line and atomized in the air supply line prior to introduction into the resin such that the atomized catalyst is thoroughly mixed with the resin in the mixing tube.

It is another object of the present invention to provide a spray gun having means for supplying an air/catalyst mixture to the resin wherein the resin does not foul the air supply means.

It is a further object of the present invention to provide a spray gun having means for preventing unmixed catalyst from being discharged from the end of the supply line when the spray gun is not in use.

These and other objects of the present invention will become apparent with reference to the following description, drawings and claims.

By the present invention, it is intended to overcome the difficulties encountered heretofore. To this end, a catalyst and resin sprayer is provided that is capable of providing a resin that merges with a catalyst so that the catalyst is introduced into and atomized by pressurized air before the catalyst is introduced with the resin. The sprayer is capable of applying a resin/catalyst mixture to a surface to provide a catalyzed resin coating on the surface. The sprayer has a mixer capable of receiving the resin and the catalyst and mixing them into a substantially homogeneous mixture. Means operatively connected to the mixer for directing the resin and catalyst to the mixer are also provided on the sprayer.

To which a device for supplying pressurized air into the mixer is operatively connected. The catalyst is introduced into and atomized by the pressurized air before the catalyst is introduced into the resin in the mixing tube. After introduction into the mixing tube, the pressurized air/catalyst acts to mix the catalyst and resin and assist in ejecting the catalyst and resin mixture from the end of the mixing tube. Means are also provided for spraying the atomized resin and catalyst stream onto a surface to form a catalyzed resin coating on the surface. Operatively connected to the charge air supply means is means for preventing resin from entering the charge air/catalyst supply means.

In one embodiment of the invention, the means for preventing resin in the mixer from entering the pressurized air supply includes a check valve having a teflon seat and a stainless steel stop held in the seat by a spring. The tension on the spring is adjusted so that the stop moves away from the seat only when the pressure of the air/catalyst on the seat is greater than the pressure of the resin on the seat.

Drawings

FIG. 1 is a perspective view of the spray gun of the present invention;

FIG. 2 is a front view of the lance of FIG. 1 with the static mixer removed;

FIG. 3 is an exploded perspective view of the nozzle end, ferrule and disposable static mixing tube of the present invention;

FIG. 4 is a top cross-sectional view of the manifold of the present invention;

FIG. 5 is an exploded view of the spray gun of the present invention; and

FIG. 6 is a side cross-sectional view of the check valve of the present invention.

Detailed Description

In the drawings, a resin application system, specifically a spray gun 10, is provided with a manifold 12, the manifold 12 having a catalyst inlet 26 and a resin inlet 27 (fig. 1 and 4). The spray gun 10 is used to apply a densely packed system to a surface. Examples of fillers that may be added to the resin to reduce cost or improve quality include: silicates, ceramic, gypsum, wood fillers, calcium carbonate, cellulose, glass fibers, and gel coats. These fillers serve as extenders or reinforcing agents for the base resin. It should be noted that although the present invention is primarily described herein as being used with a resin/catalyst introduction system, the apparatus and method of the present invention may be used with many other systems for many other purposes including spraying.

As shown in FIG. 1, a disposable static mixing tube 82 extends from the manifold 12 and terminates in a nozzle end 86. The gun 10 has an air tube 122, the air tube 122 being in fluid communication with the static mixing tube 82 for atomizing and spraying the catalyzed resin from the static mixing tube 82 through the nozzle end 86. The catalyst is introduced into the air supply line before the air/catalyst mixture is introduced into the resin in the static mixing tube 82. In one embodiment of the invention, the manifold 12 is a tooled aluminum block approximately fifteen centimeters wide, ten centimeters long, and three centimeters deep (FIG. 1). The manifold is a drilled one-piece block having a top 14 and a bottom 16. Secured to the bottom 16 of the manifold 12 is a wedge-shaped handle 17, the handle 17 preferably being a turn switch handle 19. The angle of the handle 17 makes it easier to hold the gun 10 while it is being operated.

In one embodiment, the manifold 12 is tooled with grooves that form two cylindrical passages, a catalyst passage 18 and a resin passage 20 (FIG. 4). The resin passage 20 begins at one end of the manifold 12 and terminates at the other end of the manifold 12 where the resin is directed into the static mixing tube 82. The catalyst passage 18 begins at one end of the manifold 12 and terminates at the other end of the manifold 12 where the resin is directed into the charge air supply line. In an alternative embodiment, the manifold 12 is not required, as the resin can be introduced directly into the static mixing tube 82, and the catalyst can be introduced directly into the air supply line. Preferably, these channels 18, 20 are not provided with check valves or O-rings. Since the resin and catalyst do not mix within the manifold 12, there is no need to provide check valves to prevent backflow of catalyzed resin into the passages 18 and 20. The O-ring associated with such check valves may also be eliminated. Thus, the gun 10 has a longer life than conventional guns, which must be overhauled or discarded as the manifold O-ring becomes coated with hardened resin.

Preferably, a pressure gauge 24 is connected to the catalyst passage 18, the pressure gauge 24 being mounted to the exterior of the manifold 12 and operatively connected to the passage 18 to allow an operator to know the pressure at which the catalyst moves through the passage 18 (FIG. 4). The pressure gauge 24 is very effective as an alarm means for the present invention, which not only alerts the operator of a problem occurring, but also diagnoses the problem.

Preferably, the pressure gauge 24 measures pressure from zero to over one thousand pounds per square inch. As discussed further below, during normal operation, the spray gun 10 operates at a catalyst pressure of about ninety to one hundred thirty pounds per square inch because the catalyst pressure need only match the air pressure to unseat the check valve 107 and allow catalyst to flow through the system. If the pressure drops below ninety pounds per square inch, a pump (not shown) providing catalyst to the gun 10 should be adjusted to increase the flow of catalyst through the gun 10. If the pressure rises rapidly beyond about one hundred thirty pounds per square inch, it is likely that a resin clog will plug the gun 10. Then any blockages must be cleared. If the pressure rises and falls between zero and normal pressure, the catalyst pump may only pump on one stroke rather than two. The pump must then be repaired to ensure accurate application of the catalyst and resin. While a catalyst pressure range of between ninety and one hundred thirty pounds per square inch is exemplified, the pressure may be lower or higher depending on the particular application.

Preferably, a stainless steel catalyst pipe fitting 28 (FIG. 5) is mounted on the catalyst inlet 26 of the manifold 12. It is important to ensure that all parts of the device that come into contact with the catalyst do not react with the catalyst. Methyl ethyl ketone peroxide and aluminum or similar active materials can cause fatal explosions. The fitting 28 consists of a short section of tubing connecting the manifold 12 to a catalyst ball valve assembly 30. The catalyst ball valve assembly 30 is preferably a one-quarter inch high pressure ball valve constructed of stainless steel to avoid reaction with the catalyst. The ball valve assembly 30 is connected to a threaded catalyst line connection 32, which catalyst line connection 32 allows the lance 10 to be connected to and disconnected from a catalyst supply (not shown). Thus, the ball valve assembly 30 acts as a "trigger" or on/off valve to start and stop the flow of catalyst through the gun 10.

Preferably, a restricted orifice union 22 (FIG. 5) is connected to the resin inlet 27 of the manifold 12. The restricted orifice union 22 is comprised of an orifice nipple 34, a coupling nut 36 and a resin connecting tube 38. The coupling nut 36 is slidably engaged with the resin connection pipe 38, and is prevented from falling off from the end of the resin connection pipe 38 by a flange 35 provided on the end of the resin connection pipe 38. A pair of O-rings 40a and 40b and an orifice plate 42 are provided between the orifice joint 34 and the resin connection pipe 38. The orifice plate 42 is provided with an opening having a diameter smaller than the inner diameter of the orifice nipple 34. The orifice plate 42 is located between the orifice nipple 34 and the resin connection pipe 38, and the coupling nut 36 is screwed onto the orifice nipple 34. Coupling nut 36 is tightened until orifice plate 42 is compressed between O-rings 40a and 40b sufficiently tightly to prevent resin from passing between O-rings 40a, 40b and orifice plate 42.

The diameter of the orifice in the orifice plate 42 is slightly smaller than the inner diameter of the resin connection pipe 38 so that the blockage passing through the resin connection pipe 38 stops at the orifice plate 42 before entering the manifold 12. When such a blockage occurs, the spray force from the gun 10 is greatly reduced, thus informing the operator that the coupling nut 36 must be removed from the orifice nipple 34. After the coupling nut 36 has been removed from the orifice nipple 34, the orifice plate 42 is removed, clearing the resin connection tube 38 of any blockages. Thus, the restricted orifice union 22 allows rapid removal of the blockage in situ. The restricted orifice coupling 22 is extremely useful because it does not require any tools to remove the blockage from the resin line, even in the field. It is necessary to remove the blockage from the line before it reaches the resin passage 20 of the manifold 12, otherwise, a significant amount of overhaul time would be required to remove the blockage within the resin passage 20 (fig. 4 and 5).

A resin ball valve assembly 44 (fig. 5) is connected to the resin connection pipe 38. The resin ball valve assembly 44 is a one-quarter inch high pressure stainless steel ball valve, preferably capable of withstanding pressures up to two thousand pounds per square inch. A T-valve adaptor 46 connects the resin ball valve assembly 44 to a T-valve 48. The right angle connection of the T-valve 48 is connected to a fluid relief valve 50. in the preferred embodiment, the fluid relief valve 50 is an 3/8 inch standard ball valve. The opposite end connection of the T-valve 48 is connected to a fluid hose T-adapter 52. The fluid hose T-adapter 52 allows for quick connection and disconnection of the spray gun 10 to resin hoses and supplies. The resin relief valve 50 allows resin to be expelled from the valve 50 to prevent excessive pressure build up and damage to more delicate parts of the gun 10.

The safety valve 50 is provided with a handle 51 for opening and closing the valve 50. The handle 51 may be opened and the valve 50 placed over a resin reservoir (not shown) to clean the air line prior to spraying. The valve 50 may also be used to circulate resin that has been idle in the line for an extended period of time to prevent resin that has come to rest from being applied to a surface.

Operatively connected between the catalyst ball valve assembly 30 and the resin ball valve assembly 44 is a ball valve yoke 54, which ball valve yoke 54, when rotated, simultaneously opens both the catalyst ball valve assembly 30 and the resin ball valve assembly 44 (fig. 5). The ball valve yoke 54 is comprised of two components, a catalyst connector 56 and a resin and handle connector 58. The catalyst connector 56 is a cylindrical member made of metal that fits over the catalyst ball valve assembly orifice control 60 and is attached to the catalyst ball valve assembly orifice control 60 by set screws 62.

The resin and handle connector 58 is also a cylindrical member made of steel, but which fits over the resin ball valve orifice control 64 (FIG. 5). The resin and handle connector 58 is attached to the resin ball valve bore control member 64 by a set screw 66. The inner circumference of the free end of the resin and handle connector 58 is substantially similar to the outer circumference of the catalyst connector 56. The free end of the catalyst attachment is inserted into the free end of the resin and handle attachment 58 and is attached to the resin and handle attachment 58 by a thumb screw 68.

A switch handle shaft 70 is secured to the resin and handle connector 58. In the preferred embodiment, the switch handle shaft 70 is a steel rod threaded on either end. One end of the shaft 70 is threaded into the resin and handle connector 58 and the handle ball 72 is threaded to the opposite end of the switch handle shaft 70 to make the shaft 70 easy to grasp and manipulate.

In one embodiment of the invention, when the axis is perpendicular to both the catalyst pipe nipple 28 and the orifice nipple 34, the ball valves 30 and 44 are closed, thus preventing catalyst or resin from flowing into the manifold 12 of the spray gun 10. When the handle ball 72 is pushed toward the manifold 12, the catalyst and resin ball valve assemblies 30 and 34 open, thereby allowing catalyst and resin to enter the catalyst and resin passages 18 and 20 of the manifold 12 (fig. 4 and 5). It should be noted that other valves known in the art capable of starting and stopping the flow of fluid may be used in place of the above-described components.

In one embodiment, the resin passage 20 is exposed at the forward end of the manifold 12 on the ferrule mount 74 (FIG. 4). The ferrule mount 74 is a cylindrical projection that extends forwardly from an output end 76 of the manifold 12. The outer circumference of the ferrule mount 74 is threaded so that the ferrule 78 may be screwed onto or off of the manifold 12 (fig. 3-4). The resin passageway 20 exits from the kidney-shaped aperture 79 in the ferrule mounting member 74 (fig. 2 and 4). The resin is then introduced into the static mixing tube 82 as described in further detail below.

The catalyst passages 18 emerge from the manifold 12 and lead into an air supply line (fig. 5) where the catalyst mixes with and is atomized by the charge air entering the system through the air tube 122. Preferably, the catalyst passes through a screen filter 111, a first check valve 107, and a proportioning hole 109 (FIG. 5) before entering the air line. The screen filter 111 prevents large pieces of catalyst material from entering the system so that the large pieces of catalyst material do not clog the proportioning hole 109 and affect the amount of catalyst entering the system. The proportioning hole 109 has a predetermined diameter that helps ensure that the proper amount of catalyst is introduced into the air line. If more catalyst is required, a proportioning hole 109 with a larger diameter is used. If less catalyst is required, a smaller diameter proportioning hole 109 is used.

The first check valve 107 may be similar to the check valve shown in fig. 6. The primary function of this first check valve 107 is to prevent catalyst from being discharged from the catalyst supply line when the device is shut off, i.e. when catalyst is not being pumped through the system. As described above, the prior art device wastes a significant amount of catalyst and resin because the catalyst in the catalyst line between the on/off valve (ball valve yoke 54) and the end of the catalyst line is allowed to drain from the catalyst line when the spray gun 10 is shut off. The prior art spray guns require the catalyst and resin to flow within the spray guns for a period of time before they can be used to ensure that the catalyst is properly mixed with the resin, thus wasting resin and catalyst. The first check valve 107 of the present invention overcomes this problem because the first check valve 107 closes when the supply of catalyst is shut off, thereby not allowing any catalyst to drain from the end of the catalyst line.

A unique feature of the present invention is that the catalyst pressure need only match the air pressure to unseat the check valve 107 and allow catalyst to flow through the system. As noted above, many prior art devices require the catalyst pressure to match the resin pressure (which may be about 3000 pounds per square inch) to ensure that the resin does not back-flow into the catalyst line. The design of the present invention overcomes the need to introduce the catalyst at such high pressures because the catalyst is introduced through the air supply line and only needs to match the pressure of the incoming air, which is typically much less than the pressure used to introduce the resin. Typically, in the present invention, air pressure is introduced between about ninety and one hundred thirty pounds per square inch and flows at about ten cubic feet per minute (cfm).

After passing through the first check valve 107, the catalyst is directed into the air supply line, preferably into the ninety degree adapter 120 of the air line as shown in FIG. 5. It should be noted, however, that the catalyst may be introduced into any suitable portion of the air supply line including the air pipe 122. The catalyst then passes through the second check valve 106 and eventually enters the mixing tube 82 where the atomized catalyst mixes with the resin in the mixing tube 82. The second check valve 106 prevents backflow of resin into the air/catalyst supply line. Check valve 106 is comprised of a bolt 108 and a closure mechanism 110 (fig. 6). The bolt 108 is hollow and is provided with a spring 112, and a spring mount 114 operatively connected to one end of the spring 112 and the bolt 108. The opposite end of the spring 112 is connected to a frusto-conical stainless steel stop 118. The spring 112 retains the stop 118 within a teflon seat 116 secured to the periphery of the bolt 108. The teflon polytetrafluoroethylene seat 116 is designed to engage the surface of the stop 118 and prevent material from passing between the seat 116 and the stop 118 into the bolt 108. The stopper 118 and the seat 116 are preferably constructed of different materials, such as stainless steel and Teflon polytetrafluoroethylene, to prevent catalyzed resin from sealing the stopper 118 to the seat 116 during operation of the gun 10.

In one embodiment shown in fig. 6, the wall 113 of the bolt 108 extends a predetermined distance beyond the seat 116. The diameter of the groove formed by the extended wall 113 is slightly larger than the diameter of the stopper 118 so that when the valve 106 is in the open position, the air/catalyst mixture flows between the stopper 118 and the extended wall 113. This air flow helps to clean and prevent the accumulation of any resin that has made way to the stop 118 of the valve 106.

The check valve 106 is designed to have a blow-off pressure of about five pounds per square inch so that once the pressure within the bolt 108 is five pounds per square inch higher than the pressure on the spring side of the stopper 118, the stopper 118 moves out of the seat 116 to allow air to flow out of the bolt 108. A particular advantage of this configuration is that the spring 112 is always in contact with air and never in contact with the catalyzed resin. Thus, the closure mechanism 106 will prevent itself from becoming contaminated and malfunctioning due to contact with the catalyzed resin.

In the embodiment shown in fig. 5, a ninety-degree adapter 120 is used to connect the check valve 106 to an air tube 122. The air tube 122 is secured to a quick-plug disconnect 124. The air tube 122 is preferably secured to the manifold 12 by a bracket or similar securing device to locate the quick-plug disconnect 124 near the catalyst line connection 32 and the fluid hose T-adapter 52 so that all hose connections can be made quickly and easily.

The static mixing tube 82 is placed over the ferrule mount 74, and the ferrule 78 is placed over the mixing tube 82, slid down the tube 82, and screwed onto the ferrule mount 74 to secure the static mixing tube 82 to the manifold 12 (FIGS. 1 and 5). In a preferred embodiment, the static mixing tube 82 is made of an inexpensive lightweight plastic such as polyethylene or polypropylene. These materials ensure that the tube 82 does not add additional weight to the spray gun 10 and that the tube 82 can be discarded each time the spray gun 10 stops spraying resin long enough to allow catalyzed resin to accumulate within the tube 82. The rear end of the tube 82 has a flange to prevent the tube 82 from being removed from the manifold 12 after the ferrule 78 is screwed into place (fig. 1 and 3). The forward end of the static mixing tube 82 is threaded on its inner circumference so that the nozzle tip body 84 can be screwed into the tube 82. A nozzle end 86 is secured to the nozzle end body 84 to controllably dispense catalyzed resin discharged from the spray gun 10. The threads on the static mixing tube 82 provide the nozzle end 86 with the ability to be quickly disconnected from the static mixing tube 82 by hand to remove blockages during operation of the gun 10.

Disposed within the static mixing tube 82 and extending the entire length of the tube 82 is a helical mixer 88 (fig. 3). The helical mixer 88 is preferably in the form of reverse-rolled segments, each segment of which is rolled in reverse with an adjacent segment. This form is continuous along the length of the helical mixer 88 to allow the catalyst and resin to mix evenly as they pass through the static mixing tube 82. The tube 82 and the helical mixer 88 are preferably molded from inexpensive plastic so that the catalyzed resin does not need to be removed from the tube 82 after spraying. Instead of washing the tube 82 with an expensive and dangerous solvent such as acetone, the tube is set aside until the resin hardens within the tube 82. The tube 88 is also less harmful to the environment than a plastic rod after the resin has hardened, and can simply be discarded after use. Thereby avoiding unnecessary diffusion of toxic solvents into the environment.

The side of the static mixing tube 82 is provided with a hole 83 and a chamfered air supply tube end 90 is provided in said hole 83 (fig. 3 and 5). The air/catalyst mixture enters the mixing tube 82 through the tube end 90 and mixes in the mixing tube 82 with the resin already present in the mixing tube 82. Atomizing the catalyst in the air supply line prior to introducing the catalyst with the resin helps the catalyst mix with the resin in the tubes. As discussed above, some prior art devices are inefficient at mixing resin and catalyst because the catalyst and resin form their own separate paths as they move through the mixing tube 82. Air pressure also helps the densely packed system with resin, filler and catalyst to be sheared (shear) at the nozzle end 86. A rubber end seal 92 is provided between the tube end 90 and the static mixing tube 82 to prevent air and catalyzed resin from exiting the static mixing tube 82 through the holes 83 as shown in fig. 4 and 5.

The air supply tube end 90 is held in place by a connector assembly 94 (fig. 5). The tube end holder 96 is preferably made of sheet metal and is designed to fit around the tube end 90 and half-way around the static mixing tube 82. The ends of the tube end supports 96 extend away from the static mixing tube 82 but parallel to each other. The fastening bracket 98 is formed of a thin sheet of metal to fit tightly around half of the circumference of the static mixing tube 82. The ends 100a, 100b of the fastening bracket 98 extend outwardly from the static mixing tube 82 but parallel to the ends 102a, 102b of the tube end bracket 96. The ends 102a, 102b of the tube end bracket 96 and the ends 100a, 100b of the securing bracket 98 are provided with holes so that they can be secured together. In a preferred embodiment, one set of ends 100a and 102a is fastened by nut and bolt, while the other set of ends 100b and 102b is fastened by a much larger ball screw 104. The ball screws 104 are provided so that the connector assembly 94 can be easily manipulated by an operator in the field to remove the static mixing tube 82.

To begin the application of catalyzed resin, fluid hose T-adapter 52 is connected to a line supplying resin such as polyester and catalyst line connector 32 is connected to a line supplying catalyst such as methyl ethyl ketone peroxide (FIG. 5). The quick-plug disconnect 124 is connected to the air supply line to initiate air flow through the air tube 122. The nozzle end 86 of gun 10 is directed toward the object to be treated with the nozzle end 86 and the nozzle end 86 is maintained at a distance of about twelve inches from the surface of the object while the treatment is being performed. Gun 10 is grasped tightly by handle 17 while switch handle shaft 70 is moved slowly forward to open ball valve assemblies 30 and 44 (fig. 1). The catalyst gauge 24 is monitored at the appropriate pressure as the catalyst and resin begin to flow through the manifold 12. The resin passes through the manifold 12 and into the static mixing tube 82. The catalyst passes through the manifold 12 and into the air supply line where it is atomized and then introduced into the static mixing tubes 82. As the resin combines with the catalyst in the mixing tube 82, air supplied through the mixing tube tip 90 forces the catalyzed resin through the nozzle tip 86. As the catalyzed resin passes through the nozzle end 86, the catalyzed resin is sheared and dispersed.

When a particular spray application has been completed, the switch handle shaft 70 is moved back to stop the flow of catalyzed resin and then the air supply is turned off (fig. 1). The thumb screw 104 is loosened to allow the air supply tube end 90 to be pulled out of the hole 83 in the static mixing tube 82 (fig. 3 and 5). The ferrule 78 is unscrewed from the ferrule mount 74 and the static mixing tube 82 is removed from the gun 10. The nozzle tip body 84 and nozzle tip 86 are removed from the static mixing tube 82 and the ferrule 78 is slid off of the static mixing tube 82. The nozzle tip body 84, nozzle tip 86, and ferrule 78 are thoroughly cleaned and the catalyzed resin remaining within the static mixing tube 82 is allowed to harden within the static mixing tube 82. Once the catalyzed resin within the static mixing tube 82 has hardened, the tube 82 is no longer environmentally hazardous and can therefore be disposed of in a landfill or similar disposal.

When it is desired to begin spraying, the ferrule 78 is slid onto a new static mixing tube 82 and the spray tip body 84 and spray tip 86 are connected to the new static mixing tube 82 (fig. 1 and 3). The tube 82 is then mounted to the manifold 12 by the ferrule 78, and the end seal 92 is connected to the static mixing tube 82 by the connector assembly 94.

The unique design of the present invention provides a resin/catalyst mix that mixes more thoroughly than any of the prior art spray guns known to the applicant. Introducing the catalyst into the air supply line and atomizing before introducing the catalyst into the resin provides for adequate and uniform mixing in the static mixing tube 82. In addition, the catalyst need only be introduced into the system at approximately the same pressure at which the air is introduced, which is much lower and safer than introducing the catalyst at the same pressure at which the resin is introduced. The spray gun 10 allows resin to be applied to objects in the range of one million centipoise (cps), whereas the maximum viscosity that most prior art guns can apply is only 20,000 cps. The ability to spray a resin with greater viscosity, which may or may not be densely filled with filler, allows layers of more than one centimeter in thickness to be sprayed onto a surface with each pass. This device also reduces the amount of solvent that must be added to the resin during the manufacturing process. Thus, the amount of solvent added to the resin is reduced and thus the amount of solvent that eventually evaporates into the air is reduced. The internal mixing nature of the present invention also reduces the amount of catalyst atomized directly into the air and allows the present invention to be used in areas where external mixing equipment is disabled or where emissions are prohibited by law.

Another advantage of the spray gun 10 is the elimination of any O-rings within the manifold 12. Typically, the spray gun has a check valve located within the manifold to prevent mixing of the catalyst with the resin where a solvent flush (solvent flush) cannot be reached. These check valves typically use O-rings to obtain a tight seal with the manifold. These O-rings often burst or break after prolonged contact with catalyst, resin and solvent, thus allowing the catalyzed resin to pass through the O-rings. Once the catalyzed resin hardens near or behind the O-ring, the entire manifold must be disassembled and repaired. Furthermore, the manifold is often damaged during removal of the damaged O-ring, thus requiring replacement of the entire spray gun. Since a typical spray gun may cost more than two thousand dollars, removing easily damaged parts such as O-rings like this invention is of great value to the industry.

The foregoing description and drawings merely explain and illustrate the invention and the invention is not limited thereto but only to the extent defined by the claims, and those skilled in the art will be able to make modifications and variations thereto without departing from the scope of the invention.

Claims (10)

1. An applicator capable of providing a first liquid merged with a second liquid, the second liquid being combined with a flow of pressurized air prior to its introduction into the first liquid, the applicator comprising:

a first liquid passage for passing the first liquid through the applicator, a second liquid passage for passing the second liquid through the applicator, and a pressurized air passage for passing the pressurized air through the applicator, wherein the second liquid passage is injected into the air passage such that the second liquid combines with the flow of pressurized air before it is introduced into the first liquid.

2. An applicator capable of providing a first liquid merged with a second liquid, the second liquid being combined with a flow of pressurized air prior to its introduction into the first liquid, the applicator comprising:

a first liquid passage for passing the first liquid through the sprayer;

a second liquid passage for passing the second liquid through the sprayer;

a pressurized air passage for passing the pressurized air through the sprayer, wherein the second liquid passage is injected into the air passage such that the second liquid combines with the flow of pressurized air before it is introduced into the first liquid; and

a mixer capable of receiving the first liquid, the second liquid, and the pressurized air after the second liquid has been combined with the pressurized air, the mixer capable of mixing the liquids into a substantially homogeneous mixture prior to ejecting the mixed liquids therefrom.

3. The sprayer of claim 2, wherein the mixer is a disposable mixer removably attached to the manifold such that the disposable mixer can be easily removed from the manifold and replaced.

4. An applicator capable of providing a first liquid merged with a second liquid, the second liquid being combined with a flow of pressurized air prior to its introduction into the first liquid, the applicator comprising:

a first liquid passage for passing the first liquid through the sprayer;

a second liquid passage for passing the second liquid through the sprayer;

a pressurized air passage for passing the pressurized air through the sprayer, wherein the second liquid passage is injected into the air passage such that the second liquid combines with the flow of pressurized air before it is introduced into the first liquid; and

a first check valve between the second liquid passage and the air passage, wherein the first check valve is adapted to close and prevent the second liquid from being discharged from the second liquid passage when the second liquid is not pumped through the second liquid passage.

5. The sprayer of claim 4, wherein the first check valve comprises a bolt frame having a wall and a stop fitting into a seat; and is

Wherein the wall of the frame extends longitudinally outward beyond the seat such that the stopper is retained within the extended wall when the stopper is removed from the seat to allow the second liquid to pass through the check valve.

6. The sprayer of claim 1, further comprising a second check valve downstream of the intersection of the second liquid passage and the air passage, the second check valve for preventing backflow of the first liquid into the air passage.

7. The sprayer of claim 6, wherein the second check valve comprises a bolt frame having a wall and a stop fitting into a seat; and is

Wherein the wall of the frame extends longitudinally outward beyond the seat such that the stopper is retained within the extended wall when the stopper is removed from the seat thereby allowing the second liquid and pressurized air to pass through the second check valve.

8. The sprayer of claim 1, wherein the first liquid is a resin and the second liquid is a catalyst.

9. The sprayer of claim 1, further comprising a proportioning hole located on the second liquid supply line;

the proportioning hole has a predetermined diameter to help ensure that an appropriate amount of the second liquid is introduced into the air passage.

10. The sprayer of claim 9, further comprising a filter on the second liquid supply line upstream of the proportioning hole, the filter adapted to prevent large pieces of the second liquid from clogging the proportioning hole.