Friday, 18 January 2013

T 227/10 – Sharp Change?

Remember T 106/84?

In this case the Board had to deal with an appeal against the refusal of an application. The claims were directed at a packing machine for wrapping up goods in a plastic foil, comprising a heatable tear-off edge and temperature control means, arranged in such a way as to allow the separate the piece of foil in which the goods were to be wrapped from the supply.

In the closest prior art the edge was formed by a resistance heating wire whose maintenance of the desired temperature was critical and the stabilisation of which was difficult to achieve.

The technical problem to be solved resided in the provision of a simple, robust package table construction.

The solution was based on the idea of making use of the known temperature self-limiting phenomenon of PTC resistors for accurately maintaining a predetermined critical cutting temperature.

The decision of the Board, which was published in the OJ EPO in 1985, is interesting because the appellant succeeded in persuading the Board that its invention presented several secondary indicia for inventive step (change of direction in the art, surprising advantage, commercial success, long-standing great human need, achievement of simplicity with concomittant improved quality, …).

In the present case, the applicant tried to surf the same wave, but with less success.

Claim 1 of the main request before the Board (which was almost identical to claim 1 before the Examining Divison) read:
A method of refining a crystal of cyclic ester, comprising the steps of:
  • supplying a crude cyclic ester as crystalline raw materials to a vertically extending cylindrical refiner D1 from an inlet (3) provided at a lower part of said refiner D1;
  • agitating said crude cyclic ester by an agitator (2) provided in said refiner D1 while making said crude cyclic ester flow upwardly;
  • forming a downflowing melt of crystal components as refined;
  • bringing said upflowing crude cyclic ester and said downflowing melt into counter-flow contact so as to clean off the impurities adhered to the surface of the crystal and sweat out the impurities caught inside the crystal, whereby said crude cyclic ester is refined; and
  • taking out, as products, the crystals thus refined from an outlet (4) provided at an upper part of said refiner D1.
Document D6 discloses a method of purification, wherein the feed material including cyclic esters is subjected to an adsorption step in which impurities are adsorbed from the feed material. The document points out the difficulty to transfer the processes for purifying cyclic ester compositions, inter alia melt-crystallization, in controlled laboratory conditions to a commercial process because they are complex or have impractical operating parameters and the cyclic esters may degrade resulting in poor purity.

The applicant pointed out that D6 established a prejudice against applying a continuously refining tower to easily degradable cyclic esters. Melt-crystallization was cited, but merely as one of alternative methods in the course of post-adsorption treatments.

The problem to be solved in view of document D6 was the provision of a simpler and industrially better adapted method for purifying easily degradable cyclic esters.

The solution was to suppress the main purifying step on an adsorbent, and adapting the melt crystallization step destined for post-treatment in document D6 to a single-step continuously refining method, carried out in a vertically extending cylindrical refiner on a counter-current basis. It was surprising that the use of downflowing melt in a refining tower in a gravitational manner with a tight control of temperature and exposed time could lead to a purification of these unstable cyclic esters.

There was a general trend not to use the refining tower method but crystallization methods, or a distilling method. The development in the past led away from the use of a refining tower for unstable cyclic esters. T 106/84 was cited to show that a sharp change of direction should be considered as involving an inventive step.

The relevant passage of T 106/84 reads:
“The cited documents do indicate that, although the PTC elements and their characteristics were commonly known and they had been used in other fields, the packing machine industry nevertheless adhered to additional control means separate from the heating means proper, and concentrated on efforts for improving the control means. Consequently, development led away from the use of PTC elements for heating a cutting edge. What was needed was a sharp change of direction in the art and that is what the present invention has provided through the appreciation of the feasibility of using PTC elements for the novel purpose of cutting.”
The Board was not persuaded that the same could be said in respect of the present invention:

[3.3] In the absence of evidence showing a different or better technical effect provided by the claimed invention vis-à-vis document D6, the problem underlying the present application can be regarded in the provision of a further continuous process to purify crude cyclic esters, namely to remove mother liquid impurities adhered to the crystal and to those taken inside it.

[3.4] In view of the example and the general description it is considered that the problem was actually solved.

[3.5] It remains to be decided whether or not the claimed solution is obvious in view of the state of the art.

[3.5.1] Any argument related to the judicious control in the present invention of temperature and time necessary to maintain the cyclic esters in a state with no heat degradation is without any merit since the claim 1 does not recite those conditions which are, in addition not disclosed in the application. Therefore, document (E8, E1) which represents the thermal decomposition of cyclic esters depending on heat and time has no bearing with the claimed solution.

[3.5.2] The person skilled in the art seeking to find a further process to solve the problem underlying the present would know from document D6 that melt crystallisation is particularly appropriate for cyclic esters as a further purification step, after the adsorption step. Moreover, he would also know from this document that several configurations of equipment can be used to perform the said purification by-melt crystallization […]. Unless a prejudice would have prevented him, he would have considered the equipment known in the prior art.

[3.5.3] As properly noted by the examining division melt-crystallization, although after the adsorption step, is envisaged in document D6 and even said to have “a number of particular advantages”. The alleged “technical prejudice” is, therefore, without any merit. Furthermore, that document D4 relates to a process involving distilling out the dimeric cyclic ester together with a high-boiling polar organic solvent cannot confirm a general trend teaching away from using melt crystallization as further purification step.

[3.5.4] The alleged sharp change of direction relied upon, by reference to T 106/84, cannot be acknowledged because contrary to the former case cited, where the PCT resistors in the claimed packing machine functioned as stringent control means, technical effect not known from the previous uses, in the present case the melt-crystallisation as a post-purification step of cyclic esters was known from document D6.

[3.5.5] Hence, the person skilled, having no prejudice against the use of melt-crystallization as further purification step in the context of the teaching of document D6, would have looked at document D1, which describes a process to purify continuously a crystalline substance […]. It is true that the material teaching of document D1 is confined to stable substances (e.g. p-dichlorobenzene). However, the instability of cyclic esters being not an obstacle to melt-crystallization (see document D6), a device such as disclosed in document D1 would have been prima facie appropriate for implementing the purification by melt-crystallization as taught in document D6. Document D1 describes the supply of the crude crystal from the charging mouth 6 (lower part of the tower) into the purification tower by means of a screw conveyor 7. The raw materials charged into the tower are purified while being transported to the upper portion of the tower by means of the stirrer 5. The heating and melting means 1 positioned in the upper portion of the tower is maintained at the temperature of the melting point of the crystal component, or above whereby the purified crystal is melted to a liquid. A portion of the liquid descends back down through the tower and contacts the raw material crystal rising in the tower. One portion of the purified material reaching the upper portion is removed by means of products outlet 2 and the remaining liquid portion is returned to the inside of the tower […]. The person skilled in the art applying the teaching of document D6, namely adsorption step then melt-crystallization, in combination document D1 would have designed without inventive ingenuity a process falling within the definition of claim 1 and for this reason the subject-matter of claim 1 of the main request and first auxiliary request does not involve an inventive step. Documents D2, D3 and D5 disclose other crystal refining apparatuses and cannot rebut but only reinforce, if needed, this finding.

Should you wish to download the whole decision, just click here.

The file wrapper can be found here.