When a patent (or application) does not contain any evidence that the underlying problem is indeed solved, the patent proprietor (or applicant) is in a bad position because it has to argue that this was credible, on the basis of common general knowledge (CGK). This, however, will prove problematic at a later stage of the problem-solution approach where the very same CGK then suggests that this solution was indeed obvious to the skilled person.
The present case provides an example of such a situation.
Claim 1 of the main request on file read:
1. A vehicle for a hot melt ink-jet ink, the vehicle comprising from 35 to 98% by weight of a radiation curable material and a thickener, said vehicle being a thixotropic paste at 20ºC, preferably also at 25ºC, and said vehicle having a viscosity of less than 25 centipoise at least one temperature in the range of from 40ºC to 130ºC.
The Board found document D0 to be the closest prior art and then pursued the assessment of inventive step:
[3.4] As the next step according to the problem-solution approach, it is necessary to determine the problem which the claimed invention addresses and successfully solves in the light of the closest prior art.
[3.4.1] The [patent proprietor] defined the problem to be solved in view of document D0 as lying in the provision of an ink-jet ink affording better flow properties within the printer apparatus, and improved image quality and durability.
The solution as defined in claim 1 of the patent in suit relates to a vehicle for a hot melt ink-jet ink characterised in its higher content of radiation-curable material and lower content of thickener, and being a thixotropic paste at 20ºC.
[3.4.2] The board would like to emphasise in this context that the patent in suit itself does not contain a single example of a printing process employing the claimed vehicles or inks, nor has any such data been supplied by the [patent proprietor] in the present opposition/appeal proceedings.
Thus, no evidence has been provided that any of the alleged advantages have actually been achieved in comparison with the inks according to document D0 or any other prior art.
Any positive assessment in this respect can therefore only be based on CGK and the known properties of the components of the claimed compositions.
[3.4.3] Concerning the alleged advantage of improved flow properties within the printer apparatus, the [opponent] disputed that this had been plausibly demonstrated. Indeed, according the printing process disclosed in document D0, at the operating temperature of the printing apparatus, the ink is in a liquid state in the printer head […], and therefore possesses good flow properties. Therefore, it does not appear to be credible that any advantage in this respect would be observed by employing the present vehicle in the printer apparatus disclosed in document D0.
[3.4.4] The remaining two advantages relied on by the [patent proprietor] were improved print quality and durability. In view of the fact that the [opponent] explicitly acknowledged that these two advantages could be regarded as having been achieved by the subject-matter claimed, the board sees no reason to differ. Indeed, as explained in more detail under point [3.5.1] below, the paste-like consistency of the claimed vehicle at room temperature could be expected to allow controlled mingling of droplets to occur on printing, thus improving image quality. Additionally, it can be accepted that larger amounts of curable material in the ink would increase the durability of print.
[3.4.5] Consequently, the board considers it to be plausible that the problem as defined above under point 3.4.1 has been successfully solved as far as the aspects of improved print quality and durability are concerned.
[3.5] It remains to be investigated whether the proposed solution would have been obvious to the skilled person in the light of the prior art.
[3.5.1] […] D0 already discloses the principle of combining the advantages hot-melt and radiation-curable inks by formation of inks comprising “wax and resin whose melting point is 40-70ºC” and “ultraviolet ray setting resin”. On heating, the inks become liquid and jettable, and at room temperature they return to their initial “solid or semi-solid” state […].
Through the reference to “semi-solid”, the skilled person would already derive the clear teaching that a range of consistencies may be tolerated in the inks according to document D0. Further confirmation thereof can be found in paragraph , wherein it is suggested that the viscosity of the ink at room temperature may be adjusted, as need demands.
It must be emphasised in this context that, starting from the solid ink composition specifically exemplified in document D0 and faced with problem of improving image quality and durability, the skilled person would have had at his disposal the same CGK as that relied on above under point [3.4.4].
Thus, as outlined above under point [3.4.4], the skilled person would have been aware of the fact that a vehicle having a semi-solid or paste-like consistency would allow controlled mingling of droplets to occur. This is also derivable from document D0 itself, which discloses that liquid inks suffer from colour bleed […], whereas no spread of the ink droplets occurs in the exemplified solid inks […]. It follows that a substance having an intermediate viscosity behaviour, between that of a liquid and a solid, would be expected to provide the required intermediate extent of mingling of droplets, and thus provide a solution to the problem of image quality.
Moreover, the skilled person would have been aware of the properties imparted by the various components of the ink according to document D0. Thus, the known purpose of the radiation-curable component in ink-jet inks is to provide a hardened film when subjected to an external energy source […]. Therefore, as outlined above under point [3.4.4], greater amounts of curable material in the ink would be expected to increase the durability of print.
Similarly, the wax component in document D0 is known to impart the solid consistency of the ink at room temperature […].
In view of the above, it would be within the normal routine of a skilled person, and within the teaching of document D0, to adapt the exemplified ink composition in order to achieve the optimum balance of properties required for achieving image quality and durability, namely, by decreasing the amount of wax, in order to produce a product that was semi-solid at room temperature, and by increasing the amount of radiation-curable material, in order to improve hardening. […]
The [patent proprietor’s main request is rejected for lack of inventive step.
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