T 2169/21 22-04-2024

Reasons for the Decision

1. Decision in written proceedings

Both the patent proprietor and opponent 1 withdrew their appeals and confirmed that they would not be attending the oral proceedings. Their declarations confirming that they would not be attending are considered to constitute a withdrawal of their requests for oral proceedings (see Case Law of the Boards of Appeal, 10th edition, 2022, Chapter III.C.4.3.2).

Opponent 2's request for oral proceedings was filed subject to the Board not revoking the patent.

As the Board has decided to revoke the patent, therefore, the decision in the present case can be taken in written proceedings - in accordance with Article 12(8) RPBA 2020 and Articles 113 and 116 EPC - on the basis of the contested decision to be reviewed and the parties' written submissions.

2. Admittance of D27a and D29 by the opposition division

Documents D27a and D29 had been filed after the end of the time limits fixed under Article 99(1) EPC and Rule 79(1) EPC. The admittance of these documents was at the discretion of the opposition division (see T 1776/18, Reasons 4.6.4).

When exercising its discretion, the opposition division took into account the prima facie relevance of the late-filed documents. It follows that the opposition division applied the correct criteria when exercising its discretion.

Therefore, the Board sees no reason to interfere with the exercise of discretion by the opposition division (G 7/93, point 2.6 of the reasons).

3. Admittance of D31, D32, D33 and D34

3.1 Documents D31 to D33 were filed by opponent 2 for the first time with its reply to the statement of grounds of appeal. For the following reasons, the Board takes the view that the filing of these documents constituted a justified reaction to procedural events occurring during the opposition proceedings.

D31 can be regarded as a justified reaction to the late filing of D27a during the opposition proceedings.

D32 and D33 illustrate common general knowledge of the physical properties of tertiary amines. The filing of these documents can be seen as a justified reaction to the argument put forward by the patent proprietor that the experimental results in D18 are not credible.

Since the physical properties of tertiary amines are not dependent on a publication date, the Board does not consider it appropriate to disregard D32 simply because its publication date is unknown.

Therefore, the Board decides to admit documents D31 to D33 into the appeal proceedings under Article 12(4) RPBA.

3.2 Document D34 was filed by opponent 2 shortly after the latter had received the Board's communication under Article 15(1) RPBA.

D34 supplements the main line of argument used by opponent 2 and presented throughout the entire appeal proceedings - namely that the experimental evidence does not show a synergistic effect for the curing efficiency of amine blends according to claim 1. Therefore, it does not change the matters to be discussed, and its admittance is not detrimental to procedural economy. D34 also confirms, prima facie, the preliminary conclusion presented by the Board in its communication under Article 15(1) RPBA, namely that the experimental evidence presented by the patent proprietor does not prove the presence of a synergistic effect.

Furthermore, D34 is a declaration which had been filed by the patent proprietor itself during parallel US proceedings. It was prepared by Mr Ruppin, an employee of the patent proprietor, from whom the comparative tests D27 as filed by the patent proprietor originated. In fact, D34 encompasses the experimental evidence set out in D27 but also contains further experimental evidence which had not been reported in D27.

Therefore, D34 cannot be expected to contain any information that is surprising for the patent proprietor.

3.3 The Board further notes that the patent proprietor did not provide any arguments concerning D34 - either in relation to its admittance or in relation to its substance - but withdrew its appeal and stated that it would not be attending the oral proceedings a few months after D34 was filed by opponent 2.

3.4 In its overall assessment, the Board considers the above circumstances to constitute exceptional circumstances justifying the admittance of document D34 into the appeal proceedings under Article 13(2) RPBA.

4. Auxiliary request 7 - inventive step

4.1 Choice of closest prior art

4.1.1 The opponents and the opposition division concluded that D5 is a suitable starting point for the evaluation of inventive step.

The Board sees no reason to deviate from this assessment, since D5 explicitly relates to the use of amine blends as curing agents for binder compositions in the polyurethane cold-box process (D5, point 1). The latter is precisely the technical field of the invention in the present case (see [0001] and [0002] of the patent).

4.1.2 The patent proprietor argued that D5 was not a suitable starting point since it did not relate to the same specific purpose. The patent proprietor was of the view that only D15 should be considered as the closest prior art, since it addressed the problems associated with the odour of the amines generally used in the cold-box process and with the speed of hardening of the form - see page 2, line 31 - page 3, line 1 of D15.

This argument is not convincing.

4.1.3 Although D15 - in contrast with D5 - explicitly mentions the odour problem associated with the amines used in the cold-box process, this problem (ammonia or fish-like smell of short-chain alkylamines) is nevertheless well-known in the art. Indeed, it is an inherent property of this type of compound.

Moreover, the odour problem associated with the amines is also inherently reflected by D5 in the explanation contained therein, according to which the development of smell should be reported immediately (see D5, page 3, left column, sixth paragraph) and strict limits are to be respected for the amount of gas in the air - see point 6.3 of D5.

4.1.4 In view of the above, the Board concludes that D5 is a realistic starting point for the evaluation of inventive step.

4.2 Disclosure of D5

D5 discloses, in Chapter 3.1.3, tertiary amines which act as catalysts for the cold-box process (see Chapter 1). More specifically, it discloses that

- triethylamine (TEA)

- dimethylethylamine (DMEA)

- dimethylisopropylamine (DMIA)

or mixtures thereof can be used as catalysts.

4.3 Distinguishing features

Starting from D5, the subject-matter of claim 1 differs in that the blend of amines is chosen from

- DMEA-DMIPA, DMEA/DMPA, the blend containing from 10 to 30 parts by weight of DMEA to the total of the amine blend or

- DMEA-DEMA, and DMEA-TEA, the blend containing from 10 to 50 parts by weight of DMEA to the total of the amine blend.

4.4 Alleged synergy in terms of curing

4.4.1 The patent proprietor argues that a combination of tertiary amines provides a synergistic effect in terms of curing and that the objective technical problem can be seen as providing a binder system having improved curing properties.

This argument is not convincing.

4.4.2 Experimental results in the patent

As far as the experimental results in Tables 1 and 2 of the patent are concerned, it is undisputed that the experimental data in Tables 1 and 2 of the patent itself are not suitable for the purpose of demonstrating a synergistic effect. Indeed, the theoretical mass of the blend required for 100% curing as referred to in Tables 1 and 2 has been wrongly determined.

In response to this finding, the patent proprietor filed D27 during the opposition proceedings.

4.4.3 Experimental results in D27

The annex of D27 contains a modified version of Table 2 of the patent, which has been supplemented by further columns:

FORMULA/TABLE/GRAPHIC

and further experimental results for the following blends of tertiary amines

- 50/50 DMEA/DEMA

- 20/80 DMEA/DEMA

- 10/90 DMEA/DEMA

- 20/80 DMEA/DMIPA

- 20/80 DMEA/DMPA.

According to the patent proprietor the alleged synergistic effect can be seen in the column "ratio of total expected curing with this experimental mass ...". A ratio of 100% reflects curing as expected. A ratio of less than 100% is a sign of a synergistic effect.

For the following reasons, the Board agrees with the conclusion of the opposition division, namely that the effects demonstrated in D27 do not render it credible that the synergistic effect in terms of reactivity is achievable over the whole scope of the claim.

A) doubts generated by D27

The experimental results reported in D27 demonstrate that the choice of amine and also the amounts thereof (ratio of amines) have a great impact on the curing properties.

D27 confirms that it is not even possible to achieve a synergistic effect for the same tertiary amine blend (e.g. DMEA/DMPA 20/80) for different products (Avecure xxx/yyy) of the same binder system (the Avecure system).

Indeed, the last table on page 6 of D27 indeed confirms that, for Avecure 373/673, the "ratio of total expected curing with this experimental mass of 20/80 DMEA/DMPA blend" is clearly below 100% and therefore could be regarded as a sign of a synergistic effect. However, for Avecure 331/631, the same ratio is 102.5% and thus even suggests a worsening of the curing properties obtained by the blend.

A similar observation can be made for the results of the blend DMEA/TEA 20/80 (D27, page 5, first table). It follows that the results reported in the table on page 6 of D27 vary to a great extent from one resin to the other.

Therefore, D27 supports the Board's understanding that a surprising synergistic effect observed for a specific combination of actives cannot be generalised.

In addition to the experimental results obtained for the "ratio of total expected curing with this experimental mass" - which are clearly above and below 100% - the table on page 6 of D27 also shows results which are relatively close to 100%, such as 98.2% (Avecure 363/663, Mixture DMEA/DEMA 20/80).

As argued by opponent 2, it is questionable whether results that are very close to 100% support the presence of a synergistic effect. Indeed, the error margin for the experiments is relatively high due to the amines being dosed in portions of 50 myl.

The patent proprietor confirms - by reference to paragraph [0091] of the patent - that, depending on the reactivity of the amines used as the catalyst, the quantity of the amines can range from 0.2 ml to 1.5 ml. The patent proprietor also thereby confirms that the syringe used to inject the amine mixture into the furnace has a volume of 50 µl.

Hence, the error margin for loading a syringe is multiplied by the number of doses required to achieve 100% curing. Moreover, it follows from the fact that the last dose comprises 50 myl that a certain error margin has to be taken into account. The influence of the dose volume on the error margin is also confirmed by the table on page 9 of the patent proprietor's reply to the statement setting out the grounds of appeal (in which D24 should be read as D27). In that table, the patent proprietor presents an overview of the results calculated by the opponent 2 using a 50-myl dosage regime according to D27 and the corresponding results including an error margin for experiments using a syringe having a volume of only 10 myl.

FORMULA/TABLE/GRAPHIC

This table confirms that - in the absence of a statistically significant error margin - examples resulting in a "ratio of total expected curing with this experimental mass" of, e.g., 98.2% or higher cannot be deemed to show a synergistic effect either, since the alleged improvement is considerably smaller than the error margin.

In view of the above, the Board concludes that the further experimental results reported in D27 do not render it credible that, for the selected amines used in the experiments, a blend of tertiary amines in any ratio in any type of resin achieves a synergistic effect regarding curing.

B) doubts confirmed by D34

The doubts generated by D27 are further confirmed by D34.

D34 is a declaration by the author of D27. D34 discloses, in rows 1, 4 and 5 of Table C, the experimental results of D27 as regards the blend of DMEA/DMPA 20/80 - see last table on page 6 of D27.

However, Table C of D34 additionally reports - in row 2 (binder system Avecure 353/653) and row 3 (binder system Avecure 333/633) - on the results of further experiments relating to a blend of DMEA/DMPA 20/80.

See also D27, page 6, last table:

FORMULA/TABLE/GRAPHIC

and D34, Table C, on page 4:

FORMULA/TABLE/GRAPHIC

The ratio of total expected curing with this experimental mass of 20/80 DMEA/DMPA blend can be calculated by analogy with D27 (including the error margins as discussed above) also for the additional experiments contained in D34 - see point [10] of the submission of opponent 2 dated 28 August 2023.

For the binder system Avecure 353/653 the ratio is 101.5%, and for the binder system Avecure 333/633 the ratio is 107.2%.

FORMULA/TABLE/GRAPHIC

FORMULA/TABLE/GRAPHIC

Similar observations apply in relation to the DMEA-DEMA (20/80) amine blend - see D34, Table A, which reports on additional experiments with further binder systems such as Avecure 353/653 and Avecure 325/625.

FORMULA/TABLE/GRAPHIC

Once again, the ratio of total expected curing with this experimental mass of 20/80 DMEA/DEMA blend can be calculated by analogy with D27 also for the additional experiments reported in D34 in Table A - see point [12] of the submission of opponent 2 dated 28 August 2023.

FORMULA/TABLE/GRAPHIC

FORMULA/TABLE/GRAPHIC

The ratio of total expected curing with this experimental mass can be calculated as 101.7% for Avecure 353/653 and 98.9% for Avecure 325/625.

Since a ratio of total expected curing with experimental mass of approximately 100% or above indicates the expected curing results, or even worse, the further experimental results obtained by the patent proprietor itself, and submitted by opponent 2 as D34, further confirm - in addition to D27 - that a synergistic effect in terms of curing cannot be obtained over the claimed scope - not even for the preferred amine blends (DMEA/DMPA, DMEA/DEMA) in the preferred ratio (20/80).

4.5 Alleged synergy in terms of olfactory properties

4.5.1 The patent proprietor argues that a combination of tertiary amines provides a synergistic effect in terms of olfactory properties and that the objective technical problem to be solved can be seen as the provision of a binder system having a less unpleasant odour. In support of this allegation, the patent proprietor refers to the olfactory analytics reported on pages 3 and 4 of D27 and to the further experimental evidence presented in D27a.

For the reasons set out below, this argument is not convincing. The Board agrees with the conclusion of the opposition division that the effects demonstrated in D27 and D27a do not make it credible that the synergistic effect regarding the olfactory properties is achievable over the whole scope of protection.

4.5.2 D27 and D27a evaluate the intensity of the odour and the hedonic tone according to VDI 3882 (parts 1 and 2).

These documents demonstrate that, for a specific amine blend (30/70 DMEA/DMPA blend), an improvement in the olfactory properties can be achieved.

However, the Board is convinced that the perception of odour and the interaction of different smells vary from blend to blend. Even if a specific combination of amines in a specific ratio can be observed to have synergistically improved olfactory properties, the same effect cannot be expected for all combinations of amines and for all ratios thereof, since the interaction of odour molecules cannot generally be extrapolated.

This assessment is confirmed by D29 and D31, which report - for a 20/80 DMEA/DMPA blend, hence a blend of the same amines as used for D27 and D27a but in a different ratio - that no synergistic improvement in the perception of odour can be observed - see, e.g., D31: diagrams on pages 7 and 8, and summary.

The Board therefore concludes that the experimental evidence presented by the patent proprietor does not render it credible that a synergistic effect regarding the olfactory properties can be achieved over the whole scope of the claim.

4.6 Obviousness in view of D5

Since no synergistic effect over the whole scope of the claims has been made credible by the experimental data on file (see discussion above), the objective technical problem in view of D5 has to be formulated in a less ambitious way, namely as the provision of an alternative.

Starting from the teaching in D5, according to which a mixture of tertiary amines is used, the skilled person has to use a certain quantity of each amine.

Selecting amines in arbitrary amounts as defined in claim 1 does not require inventive skills, but - instead - falls within the scope of experimental routine of the skilled person.

4.7 Therefore, the subject-matter of claim 1 of auxiliary request 7 is obvious when starting from D5, and it does not fulfil the requirements of Article 56 EPC.

5. Auxiliary requests 8 to 16 - inventive step

5.1 The subject-matter of the independent claims according to auxiliary requests 8 to 16 has been tailored - with varying levels of generality - to blends of tertiary amines which have been tested in D27, D27a and D34.

However, as discussed above in point 2.4, a synergy regarding curing has not been demonstrated for the specific blends tested in D27, D27a and D34 (see, e.g., 20/80 DMEA/DMPA blend in combination with Avecure 331/631, Avecure 353/653, Avecure 333/633) and is hence not credible for the whole scope of the claim.

The same applies for a synergy regarding the olfactory properties, which is not considered to be achievable over the whole scope of the claim, as demonstrated by D31 - see point 2.5 above.

It follows that the subject-matter of claim 1 as defined in auxiliary requests 8 to 16 can be considered to solve the same objective technical problem as claim 1 of auxiliary request 7.

Hence, the same arguments apply for the subject-matter of auxiliary requests 8 to 16 as for auxiliary request 7.

5.2 Therefore, the subject-matter of claim 1 of each of auxiliary requests 8 to 16 is obvious when starting from D5 and does not fulfil the requirements of Article 56 EPC.

It follows that the question of whether auxiliary requests 11, 12, 15 and 16 should be admitted into the appeal proceedings does not need to be addressed.