T 1993/07 – Divergence

This decision deals with appeals against the maintenance of the opposed patent in amended form.

Claim 1 of the main request (patent as granted) read:

1. A process for producing polymer from a polymerization slurry in a loop reactor operating at a space time yield greater than 2.6 lbs/hr-gal (8.65 x 10^-5 kg s^-1dm^-3) which comprises the steps of :

• forming the polymer in the polymerization slurry, wherein the polymerization slurry comprises a liquid medium and solids;
• continuously discharging the polymerization slurry through a discharge valve into a first transfer conduit, the polymerization slurry after discharge referred to as a polymerization effluent;
• heating the polymerization effluent in said first transfer conduit to a temperature below the fusion temperature of the polymer;
• communicating said polymerization effluent through said first transfer conduit to a first flash tank wherein the pressure in said first flash tank and the temperature of said heated polymerization effluent are such as to produce a vapor from about 50% to about 100% of the liquid medium;
• condensing the vapor obtained in the first flash step by heat exchange;
• discharging from said first flash tank polymer solids to a second flash tank through a seal chamber of sufficient dimension such as to maintain a volume of polymer solids in the said seal chamber sufficient to maintain a pressure seal;
• communicating the polymer solids to a second flash tank;
• exposing the polymer solids to a pressure reduction from a higher pressure in the first flash tank to a lower pressure in said second flash; and
• discharging the polymer solids from said second flash tank.

Claim 1 as held allowable by the Opposition Division (OD) read:

1. A process for producing polymer from a polymerization slurry in a loop reactor operating at a space time yield greater than 2.6 lbs/hr-gal (8.65 x 10^-5 kg s^-1dm^-3) which comprises the steps of :

• forming the polymer in the polymerization slurry, wherein the polymerization slurry comprises a liquid medium and solids;
• continuously discharging the polymerization slurry through a discharge valve into a first transfer conduit, the polymerization slurry after discharge referred to as a polymerization effluent;
• heating the polymerization effluent in said first transfer conduit to a temperature below the fusion temperature of the polymer;
• communicating said polymerization effluent through said first transfer conduit to a first flash tank wherein the pressure in said first flash tank and the temperature of said heated polymerization effluent are such as to produce a vapor from about 50% to about 100% of the liquid medium;
• condensing the vapor obtained in the first flash step by heat exchange;
  
• discharging from said first flash tank polymer solids to a second flash tank through a seal chamber of sufficient dimension such as to maintain in the said seal chamber a volume of polymer solids being a continuous plug flow having an l/d ratio of from 1.5 to 8 and being sufficient to maintain a pressure seal;
  
• communicating the polymer solids to a second flash tank;
• exposing the polymer solids to a pressure reduction from a higher pressure in the first flash tank to a lower pressure in said second flash; and
  
• discharging the polymer solids from said second flash tank.
  

In its statement of grounds of appeal filed on March 7, 2008, the patent proprietor filed a main request (rejection of the oppositions), a first auxiliary request (maintenance in amended form) and an second auxiliary request (maintenance of the patent as maintained by the OD).

On September 22, 2011, i.e. shortly before the oral proceedings (OPs) held on October 13, 2011, the patent proprietor filed five auxiliary requests. Auxiliary request 3 aimed at the maintenance of the patent as maintained by the OD and auxiliary request 5 was equivalent to the first auxiliary request filed together with the statement of grounds of appeal.

The Board found the main request to lack inventive step.

Claim 1 of the first auxiliary request read (differences with claim 1 as granted are underlined):

1. A process for producing polymer from a polymerization slurry in a loop reactor operating at a space time yield greater than 2.6 lbs/hr-gal (8.65 x 10^-5 kg s^-1dm^-3) which comprises the steps of :

• forming the polymer in the polymerization slurry, wherein the polymerization slurry comprises a liquid medium and solids;
• continuously discharging the polymerization slurry through a discharge valve into a first transfer conduit, the polymerization slurry after discharge referred to as a polymerization effluent;
• heating the polymerization effluent in said first transfer conduit to a temperature below the fusion temperature of the polymer;
• communicating said polymerization effluent through said first transfer conduit to a first flash tank wherein the pressure in said first flash tank and the temperature of said heated polymerization effluent are such as to produce a vapor from about 50% to about 100% of the liquid medium;
• condensing the vapor obtained in the first flash step by heat exchange;
• continuously discharging from said first flash tank polymer solids to a second flash tank through a seal chamber of sufficient dimension such as to maintain a volume of polymer solids in the said seal chamber sufficient to maintain a pressure seal, wherein the said chamber is of sufficient length to allow measurement and control of the solids level; maintaining a polymer solids level in the said chamber to form the pressure seal;
• communicating the polymer solids to a second flash tank;
• exposing the polymer solids to a pressure reduction from a higher pressure in the first flash tank to a lower pressure in said second flash; and
• discharging the polymer solids from said second flash tank.

The Board refused to admit this request – pursuant to Article 13 (1) and (3) RPBA – because it was late filed and raised questions regarding its compliance with A 123(2) and A 84.

It then dealt with the second auxiliary request, claim 1 of which read (differences with claim 1 as granted are underlined):

1. A process for producing polymer from a polymerization slurry in a loop reactor operating at a space time yield greater than 2.8 lbs/hr-gal (9.3 x 10^-5 kg s^-1dm^-3) which comprises the steps of :

• forming the polymer in the polymerization slurry, wherein the polymerization slurry comprises a liquid medium and solids;
• continuously discharging the polymerization slurry through a discharge valve into a first transfer conduit, the polymerization slurry after discharge referred to as a polymerization effluent;
• heating the polymerization effluent in said first transfer conduit to a temperature below the fusion temperature of the polymer;
• communicating said polymerization effluent through said first transfer conduit to a first flash tank wherein the pressure in said first flash tank and the temperature of said heated polymerization effluent are such as to produce a vapor from about 50% to about 100% of the liquid medium;
• condensing the vapor obtained in the first flash step by heat exchange;
• discharging from said first flash tank polymer solids to a second flash tank through a seal chamber of sufficient dimension such as to maintain a volume of polymer solids in the said seal chamber sufficient to maintain a pressure seal;
• communicating the polymer solids to a second flash tank;
• exposing the polymer solids to a pressure reduction from a higher pressure in the first flash tank to a lower pressure in said second flash; and
• discharging the polymer solids from said second flash tank.

As a matter of fact, this claim corresponds to the combination of claims 1 and 2 as granted. 

Will the Board admit it into the proceedings?

[6] The second auxiliary request was filed together with the first auxiliary request, and so its very late filing raises the question of its admissibility.

[6.1] The request was filed without justification as to its lateness, and with no further argumentation as to the purpose of the amendment. At the OPs, [the patent proprietor] stated that the new requests had been filed in reaction to new arguments regarding lack of novelty in the light of document D2 raised by [opponent 2] in its letter of 13 September 2011.

[6.1.1] The board observes that the claims according to this request were not only filed late but – compared to the claims as granted (main request) – also go in a completely different direction to the claims of the first auxiliary request referred to above and those held allowable by the OD. More particularly, none of the features additionally incorporated into the respective claims 1 of the latter requests concerning the dimensioning of the seal chamber have been taken over into claim 1 at issue, which only differs from claim 1 of the main request by a different lower limit of the prescribed range of STY values (2.8 in the second auxiliary request vs. 2.6 in the main request). 

[6.2] So although the amendments consist in the incorporation of features from a dependent claim into claim 1 as granted, the claims submitted as second auxiliary request “diverge” in the sense that they pursue different lines of amendment - by incorporating different features in each version - instead of increasingly limiting the subject-matter of independent claim 1 of the main request in one direction. For the board, the very late filing of the “diverging” second auxiliary request is not admissible, for the reasons set out in decision T 1685/07 [6.5-6], which the present board decided to follow. 

[6.3] The board thus decided, in the exercise of the discretion conferred on it by Article 13(1) and (3) RPBA, not to admit into the proceedings the first auxiliary request.

Finally, the Board dismissed the appeals.

I find it somewhat surprising that the second auxiliary request is criticized for going into a completely different direction than the first auxiliary request, as the latter had not even been admitted into the proceedings. All in all, this looks rather harsh.

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