content_image/921915.jpg content_image/921916.jpg
or 

<img src='content_image/921915.jpg'>

[0015] Which can also be presented as a reversible reac› tion equilibrium: 

<img src='content_image/921916.jpg'>

[0016] By removing water from the right side of the hydrolyzing reaction (la) or by removing water from elimi› nating stage in condensing reaction (1 b) with water scav› engers, one can either prevent the amines (epoxy or poly› urethane hardener compounds) to be formed in reaction (la) or to shift reaction equilibrium (1 b) to favor forming imines ( epoxy or polyurethane hardener precursors) instead of amines ( epoxy or polyurethane hardeners). 

[0017] In the prior art the inventors have added big amounts of water scavengers to control the formation of epoxy or polyurethane hardeners in the above mentioned reaction (la) between imine and water. Removing water with scavengers also shifts reaction (1 b) into formation of more imines. The amount of water scavengers used to control reactions la and lb have been so high that it has deteriorated the quality of coating to be achieved. Use of water scavengers will tend to prevent making high quality paints because surface of paint film will remain soft or brittle and making a clear coat high gloss or a colour high gloss is also impossible if high amount of water scavengers are used in an aerosol formulation to control formation of epoxy hardeners. Therefore, good quality paints cannot be prepared from these known one-can-two-component-aerosol-formu› lation(s). 

[0018] For example, the abstract of JP2004035947 dis› closes a two component aerosol formulation for an aerosol can. The formulation comprises an epoxy resin such as bisphenol A type, an imine as hardener precursor and a propellant. The drawback and challenge in this type of solution is typically the presence of moisture in the aerosol formulation causing premature hardening already in the can. Therefore, zero ambient moisture for the precursors and the packaging ambient is a key requirement. Additionally, in this patent document it has been proposed that ensuring the dry conditions should be done by adding water scavengers. As mentioned above adding water scavengers will prevent forming hardener compounds prematurely because it will affect to imine-keton balance in reactions (2a) and (2b ). However, the addition of water scavengers will affect nega› tively to paint quality and therefore the primary use of the disclosed two component aerosol of this kind is as a primer with gloss <5. 

-continued 

[0019] Patent document JP2004035947 discloses also an epoxy resin based two component aerosol formulation, which can be used in an aerosol can, wherein the epoxy resin and a hardener are mixed extended time in the same room of the aerosol can before manufacturing the paint or lacquer. However, also this patent document uses water scavengers to remove excess water from aerosol. These scavengers will make it impossible to achieve commercial 2K paints with high gloss and therefore this two component aerosol is suitable only to making primers. 

[0020] The target of the present invention was to remove drawbacks of the prior art mentioned above. 

[0021] Based on the above presented prior art there was a general need for a polyurethane based two-component aero› sol paint and adhesive system wherein an extended shelflife could be achieved without relying on the use of water scavengers, especially solid water scavengers whose use have proven problematic. 

[0022] The first main object of the present invention was to provide a polyurethane resin based aerosol dispersion, such as paint and adhesive system, that has a good stability and a long shelf life in a sealed aerosol can. 

[0023] Especially object of the present invention was to provide an aerosol dispersion in a sealed and pressurized aerosol can, which would be stable for a long time period and which would enable successful reuse after initial first usage anytime within at least a year, preferable at least three years. 

[0024] The second main object of the present invention was to control reaction equilibrium between t the polyure› thane hardener precursors and polyurethane hardeners (amines) presented in reactions la-le, so that it will also enable making high quality paints and primers. 

[0025] This second objective means that the objective of the present invention was to prevent polyurethane hardener compounds to be formed from polyurethane precursor in the polyurethane based two-component aerosol paint and adhe› sive system, without affecting negatively to the quality of the paint to be manufactured from said aerosol formulation. 

[0026] This second main objective means also that method to be used should enable making a wide range of paints with high gloss, lacquers or varnishes with high transparency, adhesives and primers with good adhesion and paints with good surface hardness and resistance to corrosion. In this connection should be noted that especially solid water scavengers will reduce the corrosion resistance; primers cannot be used as surface paints, because they include fillers (solid water scavengers) and a primer film will thus pass water. In a case an epoxy paint contains solid water scav› engers, the water can remain inside the epoxy paint when the paint film is formed. This can cause corrosion problems. 

[0027] The present invention provides a method for pre› venting hardener compounds to be formed from hardener precursors and extending the shelf life of the dispersion in the sealed can as depicted by claims 1 and 2, the method for preparing said dispersion into the sealed can as depicted in claims 15 and 16 and also a paint forming, pressurized dispersion in a sealed aerosol as depicted by claim 24. 

[0028] This inventive two-component aerosol paint and adhesive system have a long shelf life, is simple to manu- 

## DESCRIPTION OF THE INVENTION 

