Low pressure 2-K handheld spray gun

Abstract

A low pressure limited overspray handheld aerosol spray gun for spraying a two-component adhesive, a method for spraying a two-component adhesive and a two-component adhesive obtainable by that method. In manufacturing of larger objects, such as matrasses and furniture, adhesives are often applied to fix parts of the large object together. Most adhesives are applied using either air-spray equipment or air-assisted spray equipment.

Claims

1. A low pressure limited overspray handheld aerosol spray gun for spraying a two-component adhesive comprising 80-97 wt. % of a first fluid and 3-20 wt. % of a second fluid, the wt. percentage calculated on a combined first and second fluid, comprising: (a) a first and second connection for supply of the first and second fluid, respectively, (b) one first nozzle and one second nozzle, wherein the first nozzle has an opening with a first area, wherein the second nozzle has an opening with a second area, wherein a ratio between the first area and the second area is between 0.2 and 5, (c) a separate fluid passageway for the first and second fluid between the connection and nozzle, respectively, (d) a first and second mechanism for opening and closing of the passage way of each fluid to the nozzle, (e) a trigger for simultaneous control of the mechanisms, a third fluid passageway for providing air, (g) a chamber wherein the second and third passage ways enter and from which access to the second nozzle is provided, and (h) a first removable nozzle tip attached to the first nozzle, and wherein the first nozzle tip has a slit incorporated therein, and wherein the system is capable of withstanding a first fluid airless pressure of 200-800 kPa (2-8 Bar) and capable of withstanding a second fluid air-assisted pressure of 12-100 kPa (0.12-1.0 Bar).

2. The aerosol spray gun according to claim 1, wherein the second nozzle is directed such that the second fluid intimately mixes with the first fluid at a distance of 1-10 cm of the first nozzle.

3. The aerosol spray gun according to claim 1, wherein the ratio between the first area and the second area is between 0.33 and 3.5.

4. A system for spraying a two-component adhesive comprising an aerosol spray gun according to claim 1, comprising: (A) a pump for providing an airless pressure of 200-800 kPa to the first fluid, and (B) a pump for providing an air pressure of 10-100 kPa to the second fluid.

5. A method of spraying a two component adhesive comprising a first and second fluid comprising the steps of: providing an aerosol spray gun according to claim 1, providing the first fluid selected from the group consisting of polychloroprene dispersion, polyurethane dispersion, polyacrylate dispersion, vinylacetate-ethylene dispersion, ethylene-vinylacetate dispersion, natural rubber dispersion, styrene-butadiene-styrene copolymer dispersion, styrene-butadiene rubber dispersion, and combinations thereof, at an airless pressure of 200-800 kPa (2-8 Bar), providing the second fluid which comprises an activator at an air assisted pressure of 15-50 kPa (0.15-0.5 Bar), and applying the combined fluids as the adhesive to a surface.

6. The method according to claim 5, wherein the viscosities of the first- and second-fluids are in the range of 0.2 mPa*s to 10 Pa*s at 25 C.

7. The method according to claim 5, wherein pressure for spraying is provided by one or more selected from the group consisting of positive displacement pumps, pressurized systems, and gravity feed feeding systems.

8. The method according to claim 5, applying >90 wt. % of adhesive as provided to a surface.

9. An adhesive layer obtained by a method according to claim 5, the adhesive layer comprising: the first fluid selected from the group consisting of polychloroprene dispersion, polyurethane dispersion, polyacrylate dispersion, vinylacetate-ethylene dispersion, ethylene-vinylacetate dispersion, natural rubber dispersion, styrene-butadiene-styrene copolymer dispersion, styrene-butadiene rubber dispersion, and combinations thereof, and the second fluid comprising activator, and having a >95% reduced overspray and an improved homogeneity of more than 90%.

10. The use of an aerosol spray gun according to claim 1 in applying an adhesive layer, the adhesive layer comprising: the first fluid selected from the group consisting of polychloroprene dispersion, polyurethane dispersion, polyacrylate dispersion, vinylacetate-ethylene dispersion, ethylene-vinylacetate dispersion, natural rubber dispersion, styrene-butadiene-styrene copolymer dispersion, styrene-butadiene rubber dispersion, and combinations thereof, and the second fluid comprising an activator, and wherein upon application one or more is provided of limiting use of air by more than 50%, limiting overspray to less than 10 wt. %, improving mixing of first and second fluid to more than 90%, improving homogeneity of a sprayed layer to more than 90%, enlarging a width of a spray pattern by more than 20%, limiting an amount of adhesive per unit sprayed area to less than 80%, and limiting tailing to less than 10%.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more embodiments of the invention and are not to be construed as limiting the invention. In the drawings:

(2) FIG. 1 relates to a spray gun according to the invention; and

(3) FIGS. 2a-c relate to a spray gun add on according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) The present invention relates in a first aspect to a handheld spray gun according to claim 1.

(5) In an example of the present handheld spray gun the second nozzle is directed such that the second fluid intimately mixes with the first fluid at a distance of 1-10 cm of the first nozzle, preferably 2-7 cm. Is has been found that in order to reduce overspray and have a good mixing the first and second fluid mix at a certain distance from the top. Depending on a pressure applied, and to a ratio of the pressures, as well as on the nozzles provided, a distance may vary somewhat. The distance is preferably not too large, as mixing is than not optimal and overspray increases. A similar argument holds for a too small distance.

(6) In an example of the present handheld spray gun the first nozzle has an opening with a first area, preferably a circular opening, wherein the second nozzle has an opening with a second area, preferably a circular opening, wherein a ratio between the first area and the second area is between 0.2 and 5, preferably between 0.33 and 3.5, more preferably between 0.45 and 2.5, such as between 0.66 and 1.5. It has been found that the openings are relatively small, such as 0.28-0.8 mm for the first nozzle, and 0.35-1.0 mm for the second nozzle. The openings preferably have an annular form. It has also been found that the ratio of surface areas of the openings of the two nozzles is within the above mentioned ranges, despite the first fluid being provided in much larger quantities, compared to the second fluid.

(7) In an example of the present handheld spray gun is capable of withstanding a first fluid pressure of 200-800 kPa (2-8 Bar), preferably at 250-400 kPa, more preferably at 275-350 kPa. In other words, compared to other airless systems, the first fluid is provided at a relatively low pressure. It has been found that, in combination with the nozzle and nozzle tip, such a pressure provides a very good spray pattern, e.g., in terms of quantity provided per unit surface area, in terms of overspray, in terms of mixing, in terms of tailoring, in terms of amount of airborne particles, etc. The pressure used is also relatively safe for employees using the present spray gun.

(8) In an example of the present handheld spray gun is capable of withstanding a second fluid pressure of 10-100 kPa (0.1-1.0 Bar), preferably at 12-40 kPa, more preferably at 20-30 kPa. Despite the pressure being provided with air, the pressures used are surprisingly low and can be provided with e.g. a simple ring tubing for pressurized air, a container having pressurized air, etc. The amount of air used is estimated to be about 1-10% com-pared to prior art air spray guns. It is noted that the second fluid itself is pressurized as well, comparable to the first fluid, but at a lower pressure, typically at a pressure of 15-100 kPa (0.15-1.0 Bar), preferably at 20-50 kPa, more preferably at 25-35 kPa.

(9) It is noted that with the present adaptable nozzles a spray pattern can be adjusted easily, such as by adjusting a pressure. Also a mixing ratio between first and second fluid can be adjusted easily.

(10) In a second aspect the present invention relates to a system for spraying a two-component adhesive comprising an aerosol spray gun according to any of the preceding, comprising:

(11) (A) a means for providing an airless pressure of 200-800 kPa to the first fluid, and

(12) (B) a means for providing an air pressure of 10-100 kPa to the second fluid.

(13) In a third aspect the present invention relates to a method of spraying a two component adhesive comprising a first and second fluid. The method comprises the steps of providing an aerosol spray gun according to any of claims 1-5 or a system according to claim 6.

(14) The first fluid relates to a first component of a two component adhesive. It is preferably selected from a polychloroprene dispersion, polyurethane dispersion, polyacrylate dispersion, vinylacetate-ethylene dispersion, ethylene-vinylacetate dispersion, natural rubber dispersion, styrene-butadiene-styrene copolymer dispersion, styrene-butadiene rubber dispersion, and combinations thereof. The first component is preferably provided at a pressure of 200-800 kPa (2-6 Bar), preferably at 250-400 kPa, more preferably at 275-350 kPa.

(15) The second fluid relates to a second component of a two component adhesive. The second fluid is preferably an activator. It is preferably selected from a salt of a multivalent metal such as zinc, aluminum or calcium; or an acid solution, such as selected from citric acid, formic acid, acetic acid, lactic acid and mineral acid having a pH below 5, preferably below 4.5, most preferably below 4, and combinations thereof. The second component is preferably provided at a pressure of 150-500 kPa (0.15-0.5 Bar), preferably at 200-400 kPa, more preferably at 250-300 kPa.

(16) A next step relates to applying the combined fluids as an adhesive to a surface.

(17) In an example of the present method the viscosities of the first- and second-fluids are in the range of 0.2 mPa*s to 10 Pa*s at 25 C. It has been found that for intimate mixing, obtaining a good spray pattern, reducing overspray, etc., these viscosities suit particularly well.

(18) In an example of the present method a pressure for spraying is provided by one or more selected from: positive dis-placement pumps, such as double diaphragm pumps or piston pumps; pressurized systems such as pressure tanks; and, gravity feed feeding systems.

(19) In an example the present method is for applying >90 wt. % of adhesive as provided to a surface, preferably >95 wt. %, such as >98 wt. %. An amount of overspray (loss) and an amount of adhesive applied (yield) is measured according to DIN 13966 (September 2003), specifically part 1 thereof. If boundary conditions are optimized almost 100.0 wt. % is provided to an intended surface. As such the present method reduces overspray and provides further advantages, as mentioned.

(20) An amount of overspray (loss) and an amount of adhesive applied (yield) is measured according to DIN 13966, specifically part 1 thereof.

(21) In a fourth aspect the present invention relates to a use of the present spray gun or system for one or more of limiting use of air by more than 50%, limiting overspray to less than 10 wt. %, improving mixing of first and second fluid to more than 90%, improving homogeneity of a sprayed layer to more than 90%, enlarging a width of a spray pattern by more than 20%, limiting an amount of adhesive per unit sprayed area to less than 80%, and limiting tailing to less than 10%.

(22) In a fifth aspect the present invention relates to an adhesive layer, such as obtainable by a method according to the invention, amongst others having an improved homogeneity to more than 90%.

(23) The invention is further detailed by the accompanying figures and examples, which are exemplary and explanatory of nature and are not limiting the scope of the invention. To the person skilled in the art it may be clear that many variants, being obvious or not, may be conceivable falling within the scope of protection, defined by the present claims.

(24) The reference numerals used in the figures are: 10 Main Body of spray gun 20 Air input regulator 30 Opening and closing mechanism 40 Material needle 70 Nipple 80 Airless nozzle 81 Slit 90 Swivel 95 Spray gun add on 1 first and second connection 2 first nozzle and second nozzle 3 separate fluid passage ways 4 first and second mechanism for opening and closing 5 trigger for simultaneous control of the mechanisms 6 third fluid passage way 7 chamber

(25) FIG. 1 relates to a spray gun 100. Therein various elements of an example of the present spray gun can be seen. For instance an input regulator for air 20 is shown. Also a handle 60 for opening and closing is provided. Part 10 relates to a main body. Further an opening and closing mechanism 30 for air and a material needle 40 for adhesive is shown. Also an air hose to activator switch 50 is shown. Further, the elements 1-7 (found in claim 1) have been identified in the figure.

(26) FIGS. 2a-c relate to a spray gun add on 95. The add-on is for providing air pressure to a second component of the adhesive to be applied. FIG. 2a shows the assembled activator switch, whereas FIG. 2b shows construction of the switch.

(27) FIG. 2c shows a worked open version of the add on 95. Further, the elements 1-7 (found in claim 1) have been identified in the figure.

(28) It should be appreciated that for commercial application it may be preferable to use one or more variations of the present system, which would similar be to the ones disclosed in the present application and are within the spirit of the invention.