Fluid dispensing gun and method for dispensing 1 K-polyurethane foam

The invention concerns a fluid dispensing gun for 1 K-polyurethane foam comprising a dispensing tube with a dosing nozzle at its outlet, a spring-loaded needle which is co axially moveable in the dispensing tube for opening and closing the dosing nozzle, a trigger for actuating said needle in order to open the dosing nozzle and to dispense the fluid, regulating means for regulating the degree of opening of the outlet of the dosing nozzle and coupling means for coupling a pressurized can to the gun. It also concerns a method for dispensing 1 K-polyurethane foam.

A foam gun of this kind is described in EP 2 808 088 A1 .

Such fluid dispensing guns are used for dispensing foam, in particular polyurethane foam. There is 1 -K (one component) polyurethane foam that hardens under the influence of humidity contained in the air and 2-K polyurethane foam in which two components react together in order to form hardening polyurethane foam.

WO 98/30373 A1 describes a polymeric substance delivery method and device in which the outflow is determined from a first container of a monomeric substance able to polymerize autonomously upon air contact, and eventually, the outflow from a second container is determined of a hardening substance able to accelerate the polymerization of the monomeric substance, by sending the same hardening substance towards a mixing zone of the hardening substance with the same monomeric substance. The monomeric substance and the hardening substance are mixed in the mixing zone which is situated in the device and flow out of the device immediately after mixing.

WO 2005/009628 A2 describes a delivery device forming a handle, for in-situ PU foam with two or more receiver mountings for a can, such as an in-situ PUR foam can and a can of further substances and at least one delivery tube, connected to the delivery device, whereby the substances from at least two cans may be applied by the same delivery tube. The object of the invention is to shorten the hardening time of 1-K polyurethane foam dispensed by a fluid dispensing gun.

According to the present invention, this object is achieved in that the fluid dispensing gun comprises means for delivering a curing fluid separately from the 1 K- polyurethane foam in a direction which is essentially parallel to that of the outlet of the dosing nozzle of the dispensing tube, the means for delivering a curing fluid comprising a curing fluid reservoir, a curing fluid outlet situated in proximity of the dosing nozzle of the dispensing tube and a curing fluid line connecting the curing fluid reservoir and the curing fluid outlet, the means for delivering a curing fluid being activated via the trigger of the fluid dispensing gun.

When activating the trigger of the fluid dispensing gun, the means for delivering curing fluid are activated so that the fluid dispensing gun delivers both 1 K- polyurethane foam and a curing fluid (which can be water or another fluid capable to cure 1 K polyurethane) which are put out separately in essentially the same direction. The curing fluid makes the polyurethane foam cure more rapidly than with the sole humidity contained in the air. Thus, the 1 K polyurethane foam cures like a 2K- polyurethane foam and cellularity and the Lambda (l) values are improved compared to current 1 K-polyurethane foams.

According to an embodiment of the invention, the curing fluid reservoir is a

pressurized reservoir on the fluid dispensing gun provided with a valve for delivering the curing fluid from the curing fluid reservoir to the curing fluid outlet.

According to an alternative embodiment of the invention, the curing fluid reservoir is a non-pressurized reservoir on the fluid dispensing gun that comprises a pump for pumping the curing fluid from the curing fluid reservoir via the curing fluid line to the curing fluid outlet.

The curing fluid reservoir is preferably arranged on the lower side of the fluid dispensing gun. The curing fluid reservoir may be arranged in front of the trigger, e.g. in a hollow second handle of the fluid dispensing gun.

Alternatively, the curing fluid reservoir is arranged on the upper side of the fluid dispensing gun.

The curing fluid reservoir may for instance be arranged behind the can containing 1 -K polyurethane foam.

Preferably, the curing fluid reservoir is at least partly transparent.

This allows checking the curing fluid level in the curing fluid reservoir. The curing fluid reservoir can also be completely transparent.

According to an embodiment of the invention, the curing fluid outlet is designed as a spray nozzle.

This feature in connection to a sufficient pressure of the curing fluid allows delivering a spray of curing fluid in the area around the outlet of the fluid dispensing gun so that the 1 K-polyurethane foam dispensed via the outlet cures quickly.

According to a further embodiment of the invention, control means are provided for starting the curing fluid delivery upon activation of the trigger of the dispensing gun.

These control means allow defining whether the curing fluid leaves the outlet before the 1 -K polyurethane, at the same time as the 1 -K polyurethane or after the 1 -K polyurethane.

The object of the invention is also achieved by a method for dispensing 1 K- polyurethane foam with a fluid dispensing gun according to the present invention, characterized in that curing fluid is delivered via a separate fluid line in an essentially parallel direction of the outlet of the dosing nozzle of the dispensing tube of the fluid dispensing gun upon activation of the trigger of the fluid dispensing gun. According to an embodiment of the invention, the curing fluid is delivered in form of a spray.

According to a further embodiment of the invention, the curing fluid delivery starts before the delivery of the 1 K-polyurethane foam.

According to another embodiment of the invention, the curing fluid delivery starts at the same time as the delivery of the 1 K-polyurethane foam.

According to a further embodiment of the invention, the curing fluid delivery starts after the delivery of the 1 K-polyurethane foam.

In the following, a preferred embodiment of the invention is described with reference to the figures wherein

Fig. 1 shows a side view of a first fluid dispensing gun according to the

invention,

Fig. 2 shows a longitudinal cut through the fluid dispensing gun according to figure 1 ,

Fig. 3 shows a side view of a second fluid dispensing gun according to the invention with the curing fluid reservoir in an unmounted state,

Fig. 4 shows a longitudinal cut of the fluid dispensing gun according to figure 3 with the curing fluid reservoir in an unmounted state,

Fig. 5 shows a side view of a second fluid dispensing gun according to the invention with the curing fluid reservoir in a mounted state. The fluid dispensing gun according to the invention comprises a housing 1 on the upper side of which coupling means 2 for coupling a pressurized can to the gun are arranged.

The means 2 for coupling a pressurized can are connected via a fluid line to a dispensing tube 3 with a dosing nozzle 4 at its outlet. A spring-loaded needle is co axially moveable in the dispensing tube 3 for opening and closing the dosing nozzle 4.

There is a handle 5 for holding the gun during operation. The user can actuate said needle by pushing on a trigger 6 situated on the lower side of the housing 1 in front of the handle. By actuating the needle, he opens the dosing nozzle 4 in order to dispense the fluid.

At the free end of the fluid dispensing gun opposed to the dosing nozzle 4, regulating means 7 for regulating the degree of opening of the outlet of the dosing nozzle are provided. By turning these regulating means, the degree of opening of the outlet is modified.

The fluid dispensing gun according to the present invention comprises means 8, 9,

10 for delivering curing fluid to a curing fluid outlet 10 situated in proximity of the outlet of the dispensing tube 3. These means comprise a curing fluid reservoir 8, a curing fluid outlet 10 situated in proximity of the outlet of the dispensing tube 3 and a curing fluid line 9 connecting the curing fluid reservoir 8 and the curing fluid outlet 10. The curing fluid is transported and delivered separately from the 1 -K polyurethane so that no mixing thereof occurs in the fluid dispensing gun.

In the first embodiment shown in Fig. 1 and 2, the curing fluid reservoir 8 is

configured as a pressurized reservoir 8 situated on the lower side of the fluid dispensing gun in front of the trigger 6. This reservoir 8 may serve as a second handle of the fluid dispensing gun. The reservoir 8 is made of transparent material so that the curing fluid level can easily be controlled. The curing fluid outlet 10 is designed as a spray nozzle. Depending on the movement of the fluid dispensing gun during the 1 K-polyurethane application, the curing fluid outlet nozzle 10 can be turned around the dispensing tube 3 of the fluid dispensing gun.

Control means are provided for starting the curing fluid delivery when the trigger 6 of the dispensing gun is activated. These control means can be mechanical or electronic control means. When the trigger 6 is activated, the opening of the dosing nozzle 4 is preferably slightly delayed so that the surface is moistened with the curing fluid before the 1 K-polyurethane foam comes out of the dosing nozzle. The curing fluid will be sprayed while dispensing the 1 K-polyurethane foam. This solution allows moistening the area in which 1 K-polyurethane foam is sprayed afterwards.

However, it is also possible that the curing fluid delivery starts either at the same time as the delivery of the 1 K-polyurethane foam or after the delivery of the 1 K- polyurethane foam. The first solution allows moistening the 1 K-polyurethane foam upon leaving the outlet of the fluid dispensing gun and the second one allows moistening the already dispensed 1 K-polyurethane foam.

The second embodiment of the invention shown in figures 3, 4 and 5 differs from the first embodiment in that the curing fluid reservoir 8 is on the upper side of the fluid dispensing gun, just behind the means 2 for coupling a pressurized can so that the reservoir 8 and the pressurized can containing the 1 -K polyurethane are one behind the other on the upper side of the fluid dispensing can.

It can be seen from the figures 3, 4 and 5 that the fluid dispensing gun has an inner thread for fixing a ring onto which the curing fluid reservoir 8 is fixed by means of a second thread.

Furthermore, the curing fluid outlet 10 is shown on the upper side of the dosing nozzle 4 for the 1 -K polyurethane. However, it is possible to unscrew the fixation of the curing fluid outlet 10 and to turn it by 180° around the dispensing tube 3 so that the curing fluid outlet 10 is on the lower side of the dosing nozzle 4 for the 1 -K polyurethane foam. It also could be turned by another angle, e.g. by 90° in order to have the curing fluid outlet 10 at one side of the dispensing tube 3.

Instead of dispensing the curing fluid parallel to the direction of the dosing nozzle 4, it is also possible to dispense it in another direction, if suitable for the application.