T 1484/15 26-09-2018

Reasons for the Decision

Main request

Novelty over D2

1. The general principle consistently applied by the Boards of Appeal for concluding lack of novelty is that there must be a direct and unambiguous disclosure in the state of the art which inevitably leads the skilled person to subject-matter falling within the scope of what is claimed. The objection that the claimed subject-matter lacks novelty over D2 is based on the enumeration of several isolated passages of that document which relate to various possibilities encompassed by its teaching, but have not been shown to be necessarily read in combination by the skilled person. A pointer towards that combination of features taken from isolated passages of D2 was not indicated by the appellant.

2. Moreover, having regard to the feature of operative claim 1 that the dispersed polyurethane comprises a block derived from an oil B which among others is defined to have a hydroxyl number of from 120 mg/g to 230 mg/g, it is noted that the only disclosure relating to the hydroxyl number of the polyester oligomer (A) of D2 is to be found in the experimental part of that document describing the preliminary step of preparing polyester-oligomer-precursors 1 and 2 (page 4, lines 31-41).

Said oligomers are obtained by a transesterification reaction carried out on a mixture of castor (ricinus) oil (which comprises an hydroxyl group along the fatty acid chain) and soybean oil (having no hydroxyl group along the fatty acid chains). The transesterification reaction leads to a rearrangement of the fatty acid moieties between the two starting oils and as a consequence to a hydroxyl number of the obtained oil which is necessary below that of the castor oil. The two polyester-oligomer-precursors obtained in the examples exhibit hydroxyl numbers of 89 and 109 mg/g.

3. Accordingly, the polyurethane structure in accordance with the subject-matter of operative claim 1 differs from those disclosed in the examples of D2 at least in that it contains blocks derived from an ester having a higher hydroxyl number. The subject-matter of claim 1 and that of claims 2 to 5 which also incorporates the features of claim 1 is therefore novel over D2.

Inventive step

Closest state of the art

4. According to paragraph [0005] of the patent in suit, the object of the present invention is to provide aqueous polyurethane dispersions which exhibit superior wood-wetting properties, while at the same time retaining other favourable polyurethane properties in coatings prepared therefrom such as mechanical and chemical resistance.

4.1 According to D2, page 2, lines 7-10, it is advantageous to use polyurethane dispersions, especially for coating surfaces exposed to severe mechanical stress, since these dispersions combine the important properties of resistance to chemicals and mechanical stress. The aqueous polyurethane dispersions in accordance with D2 are used for the preparation of coating compositions for parquet (passage from page 5, line 56 to page 6, line 54) using in particular the polyurethane dispersion "PUR-Dispersion 1" described on page 4, lines 43-61. On this basis, as it appears from the contested decision, a suitable starting point for assessing inventive step was seen by the opposition division to be represented by D2, in particular the coating composition obtained with "PUR-Dispersion 1". This was not disputed by the parties. Having no reason to take a different view, the Board is satisfied that the coating composition of D2 prepared with "PUR-Dispersion 1" can be taken as the closest prior art.

4.2 The polyurethane of the aqueous polyurethane dispersion "PUR-Dispersion 1" comprises building blocks derived from the following educts:

- Desmodur® W (Bayer AG) and Desmodur® I (Bayer AG) which are polyfunctional isocyanates corresponding to component A of operative claim 1

- a "polyester-oligomer oil precursor 1"

- 1,6-hexanediol (component C according to operative claim 1)

- a poly(tetrahydrofuran) having a molecular weight of 2000 (optional component C' of operative claim 1) and

- dimethylolpropionic acid (component D according to operative claim 1).

The polyurethane is obtained by reaction of those compounds until a NCO content of 4,3% is obtained, followed by neutralisation with triethylamine (see also page 3, lines 65-66 of D2) and dispersion in water. Excess isocyanate groups are then reacted with hydrazine hydrate and ethylenediaamine (see also page 4, lines 1-3).

It is undisputed that the "polyester-oligomer- precursor 1" fulfills all requirements of operative claim 1 with the exception of the hydroxyl number, which is 89 mg/g as indicated in above section 2. In particular, at least 40% by weight of the fatty acids contained in this polyester-oligomer-precursor have at least one hydroxyl group as shown by the ratio of castor oil to soybean oil used for its preparation.

4.3 Accordingly, the coating compositions according to operative claim 1 differ from the coating composition of D2 using "PUR-Dispersion 1" in that:

(i) they are two-pack compositions wherein the curing agents are selected from the group consisting of non-blocked polyfunctional isocyanates I , polyaziridines Z , and carbodiimides Y,

(ii) the oil B used as a building block for the dispersed polyurethane U has a hydroxyl number of from 120 mg/g to 230 mg/g and

(iii) compounds F as defined in operative claim 1 is used as an additional building block of the dispersed polyurethane.

Problem successfully solved

5. The respondent regarded the problem solved over the closest prior art as the provision of coating compositions bringing about improved mechanical and wood application properties.

5.1 As to whether evidence has been provided that these alleged benefits resulted from the use of the distinguishing features identified in above section 4.3, the respondent relied on the results of the comparative tests mentioned in paragraph [0047] of the patent in suit. According to that paragraph [0047] a similar test to that indicated in paragraphs [0044] to [0046] of the patent in suit has been made with a polyurethane prepared according to EP 1 026 186 A1 (i.e. D4 in the present proceedings) used as comparative example. It was found that the paints 1 and 2 according to the patent in suit exhibited superior mechanical and wood wetting properties.

5.2 According to the established jurisprudence, if comparative tests are relied on to demonstrate an inventive step on the basis of an improved effect, the nature of the comparison with the closest state of the art must be such that the alleged advantage or effect is convincingly shown to have its origin in the features distinguishing the invention from the closest state of the art (Case Law of the Boards of Appeal of the EPO, 8th edition, 2016, I.D.10.9).

5.3 The comparative test referred to by the respondent which is mentioned in paragraph [0047] of the patent in suit, however, is not further specified. In particular, the nature of the compounds making the coating or even the constituents of the dispersed polyurethane prepared according to D4 as a comparative example is not indicated, which makes it impossible to assess whether any effect identified in this test could be considered to result from any of the features distinguishing the compositions of operative claim 1 from the closest prior art. The same holds true with respect to the other comparative data mentioned in paragraphs [0044] to [0046] of the patent in suit, which are based on a comparison with a commercial paint whose compositions apart from being indicated to be a two- pack aqueous polyurethane coating composition are not further specified.

5.4 Consequently, it follows that the respondent has not presented any corroborating evidence rendering it credible that the purported technical effect of improving mechanical and wood application properties in comparison to the closest prior art is achieved by the compositions of operative claim 1. Accordingly, any such advantage of the claimed coating compositions over the closest prior art cannot be taken into account for the purpose of assessing inventive step.

5.5 Accordingly, the problem successfully solved by the subject-matter of claim 1 over the closest prior art can only be formulated, in line with the arguments presented by the appellant, as the provision of further polyurethane coating compositions which are suitable for application on wood.

Obviousness of the solution

6. It remains to be decided whether the skilled person desiring to solve the problem identified above, would, in view of the closest prior art, possibly in combination with other prior art or with common general knowledge, have modified the disclosure of the closest prior art in such a way as to arrive at the claimed subject matter. In that respect, in the absence of any synergistic effect arising from the features distinguishing the claimed invention from the closest prior art, it has to be assessed separately whether each of said distinguishing features, taken alone, was obvious in the light of the prior art.

Two-pack composition

6.1 As to the possibility of preparing a two-pack composition, D2 teaches on page 4, lines 15-16 that it is possible to add cross-linking agents prior to application of the coating application, hydrophilic and hydrophobic polyisocyanate cross-linking agents being preferred for this purpose. This constitutes a clear suggestion for the skilled person that the polyurethane dispersions of claim 1 of D2, for example that exemplified on page 4, can be used in a two-pack composition also comprising a polyisocyanate cross-linking agent. Moreover, the selection of non-blocked polyisocyanates among known curing agents is a measure well known in the art, especially for preparing two-pack coating compositions to be applied not long after the curing agent has been added, and is therefore obvious for the skilled person.

The passage of D2 on page 2, lines 17-18 cited by the opposition division, which allegedly would discourage the skilled person from making a two-pack composition when starting from the teaching of D2, concerns the description of a prior art document, but does not concern the teaching of D2 in itself. That passage therefore cannot in the Board's view constitute any indication for the skilled person to go against the unmistakable suggestion provided on page 4, lines 15-16 of D2 to prepare two-pack compositions with the polyurethane dispersions taught in that document.

The respondent's argument that the skilled person would have assumed that he would be faced with the same applicability problems of two-pack coating compositions referred to on page 2, lines 17/18 of that document, namely that the application of two-components systems is comparatively complex and their range of applications limited, especially in the case of manual application or application by an artisan, is also not convincing, since it was not shown, let alone argued, that said mentioned problem has been overcome when using the two-pack coating composition of operative claim 1. Given the established principle that the answer to the question as to what a person skilled in the art would do depends on the result he wished to obtain (T 939/92, OJ EPO 1996, 309; Reasons for the decision, point 2.5.3), the use of a two-pack coating composition is considered by the skilled person as a useful and obvious measure in view of the fact that, in the present case, the skilled person is deemed to be merely seeking to provide further polyurethane coating compositions which are suitable for application on wood, i.e. regardless of their ability to be applied manually or by an artisan.

Oils B

6.2 The polyester-oligomer-precursors 1 and 2 disclosed in the experimental part of D2 are prepared by a transesterification reaction of a mixture of castor and soybean oils in a weight proportion of 2:1 in the presence of dibutyltin oxide or lithium hydroxide as transesterification catalyst, the polyester oligomers obtained exhibiting hydroxyl numbers of 89 and 109 mg KOH/g, respectively. Apart from the type of transesterification catalyst used, the synthesis conditions are identical. Both represent suitable polyester oligomers to be incorporated as building blocks of the polyurethane as shown by the preparation of the exemplified dispersions "PUR-Dispersion" 1 to 3 (pages 4 and 5 of D2).

6.2.1 Having regard to the hydroxyl number of castor oil which undisputedly is in the range of 160 to 168 mg/g, it can be seen that the hydroxyl number of polyester-oligomer- precursor 2 prepared in D2 corresponds to the expected value, which is 2/3 of the hydroxyl number of the castor oil, namely a value ranging from 107 to 112, indicating the efficiency of the catalyst used for preparing polyester-oligomer-precursor 2.

6.2.2 According to claim 1 and to page 2, lines 46-53 of D2, the polyester oligomer is obtainable from

AI) 30-85%, preferably 50-70%, of castor oil fatty acid,

AII) 10-60%, preferably 25-35%, of one or more carboxylic acids having 8 to 30 C atoms and 0 to 4 C=C double bonds and

AIII) 3-20%, preferably 5-15%, of one or more alcohols with an average functionality of 2,5 to 3,5.

It was not disputed that this definition of the polyester oligomer in D2 suggests that the weight proportions of castor and soybean oils can be broadly varied. By way of illustration, it can be calculated for example based on the content of glycerin in these oils (about 10 wt.%) and the amount of castor oil fatty acid contained in castor oil (77 to 83 wt.% indicated by the appellant based on D3, which was not disputed) that a 90:10 proportion by weight of castor oil to soybean oil would approximately correspond to a polyester oligomer obtainable from 65% of castor oil fatty acid AI), 25 % of other fatty acids AII) and 10% by weight of glycerine AIII), corresponding to amounts which are in the preferred ranges disclosed in D2.

Using such mixture of castor oil and soybean oil in a weight ratio of 90:10 would lead under suitable transesterification conditions to a maximum value of the hydroxyl number of 144 to 151 (based on the approximation that the the hydroxyl number of the resin would be about 9/10 of that of the castor oil). In other words, increasing the proportion of castor oil used in the examples of D2 will contribute to increase the hydroxyl number of the polyester-oligomer-precursors to the level defined in operative claim 1.

It is also noted for the sake of completeness that the fatty acids B2 used for the preparation of polyester- oligomer-precursors 1 and 2 of D2 already comprise at least 40% by weight of a castor oil (fatty acid B21 within the meaning of operative claim 1), so that increasing the proportion of castor oil necessarily leads to a polyester oligomer meeting that requirement.

Moreover, since the result the skilled person whished to obtain was the mere provision of further polyurethane coating compositions which are suitable for applying on wood, then all measures recommended in D2 for providing polyurethane coating compositions which are suitable for application on wood would be equally suitable and suggested. In addition, no inventive skill needs to be exercised in selecting for this purpose, for instance, a higher proportion of castor oil acid within the teaching of D2, while keeping the other conditions recommended for the synthesis of the polyester-oligomer-precursors described in the experimental part of D2. Consequently, acting routinely, the skilled person would arrive at the feature "oils B" defined in operative claim 1 without the exercise of inventive skills.

6.2.3 The fact that the hydroxyl number was not a relevant criterion according to the teaching of D2 as argued by the respondent, is not decisive, since arriving at polyester oligomers B meeting the hydroxyl number requirement of claim 1 is as shown above the mere result of an obvious choice concerning the proportion of oils used for the synthesis of said polyester oligomers. The argument that obtaining targeted hydroxyl number was not straightforward, as it did not only depend on the ratio of the oils undergoing transesterification, but also on the reaction time and the catalyst employed, also fails to convince. Being instructed in D2 to prepare the polyester-oligomers by transesterification, the skilled person would in an obvious manner when changing the proportion of castor and soybean oils take the transesterification catalyst successfully used for the preparation of polyester-oligomers 1 and 2, allowing if necessary sufficient time for the transesterification reaction to take place.

Compounds F

6.3 D2 teaches on page 4, lines 1-4 that excess isocyanate groups are reacted with polyfunctional isocyanate-reactive compounds providing chain extension. To this end, water or polyamines are preferably used, particularly preferably di- and triamines and hydrazine. Termination with a monoamine, such as for example diethylamine, dibutylamine, ethanolamine, N-methylethanolamine or N,N-diethanolamine is also possible according to that passage. Accordingly, the skilled person faced with the problem of providing further polyurethane coating compositions which are suitable for application on wood would find it obvious to use ethanolamine, N-methylethanolamine and N,N-diethanolamine, i.e. a compound F within the meaning of operative claim 1 (see paragraph [0025] of the patent in suit) in addition to or in replacement of hydrazine hydrate and ethylenediamine used for the preparation of PUR Dispersion 1.

6.4 Consequently, the skilled person faced with the problem of providing further polyurethane coating compositions which are suitable for application on wood would have arrived in an obvious manner in view of the teaching of D2 alone at the three modifications of the closest prior art identified in above point 4.3 and therefore at compositions which fall within the ambit of operative claim 1. It is therefore concluded that the subject-matter of claim 1 of the main request lacks an inventive step.

6.5 The main request is therefore not allowable.

Auxiliary requests 1 to 4

7. The parties stated that their inventive step arguments equally applied to claim 1 of auxiliary requests 1 to 4. Under those circumstances the Board has no reason to conclude that the amendments introduced into auxiliary requests 1 to 4 result in the introduction of additional distinguishing features and/or a different formulation of the problem solved over the closest prior art.

7.1 More specifically, the amendment introduced into claim 1 of auxiliary request 1, namely the restriction of the curing agent to non-blocked polyfunctional isocyanates, does not change the conclusion in respect of the main request, since the use of said curing agent is obvious as indicated in above section 6.1.

7.2 As to the amendment introduced into auxiliary request 2, namely that the fatty acid B2 comprises at least one olefinic unsaturation, this amendment does not result in any additional distinguishing feature over the closest prior art which describes the use of castor oil, which also is an unsaturated fatty acid. As regards auxiliary requests 3 and 4 their claim 1 differs from claim 1 of the main request in that process steps defining the preparation of the aqueously dispersed polyurethane U have been inserted. It has not been shown, let alone argued, that said process features would result in structural feature(s) of the claimed composition which constitute additional distinguishing feature(s) over D2. Accordingly, the additional amendments contained in claim 1 of auxiliary requests 2 to 4 cannot overcome the negative finding on inventive step in respect of claim 1 of the main request.

7.3 Consequently, none of the auxiliary requests 1 to 4 is allowable.

Auxiliary request 5 - admittance

8. The admittance to the proceedings of auxiliary request 5 submitted at the beginning of the oral proceedings underlies the stipulations of Articles 13(1) and 13(3) RPBA. That auxiliary request corresponds to the main request wherein claim 1 has been modified by amending the values of the hydroxyl number of oils B to be in the range of from 140 mg/g to 190 mg/g, instead of that from 120 mg/g to 230 mg/g.

8.1 The whole discussion in the appeal proceedings up to the oral proceedings before the Board was focused only on the obviousness of using a two-pack coating composition when starting from D2 as closest prior art. The respondent's line of defense that the skilled person based on the teaching of D2 would not arrive in an obvious way at preparing oils B with a hydroxyl number within the claimed range was put forward for the first time at the oral proceedings. In view of the fact that the appellant had already argued in its statement setting out the grounds of appeal (see passage in point 6.1.3.2, starting with the 4th paragraph on page 14), that D2 disclosed oils having the hydroxyl number required by claim 1, there was not justification for the respondent to wait until the oral proceedings to argue that preparing oils having the hydroxyl numbers defined in claim 1 of the main request was not a trivial measure for the skilled person in the light of D2, let alone to submit auxiliary request 5 which gave more strength to the respondent's new line of defense. The allegation that the relevance of the hydroxyl number had been triggered by the Board's communication therefore fails to convince and the Board finds no justification for the late filing of auxiliary request 5.

8.2 Whereas the question raised in relation to the minimum hydroxyl number defined in the main request and auxiliary requests 1 to 4 could be reasonably addressed during the oral proceedings (see in particular section 6.2.2 above), it became evident that the appellant could not adequately react to the new situation arising from the filing of auxiliary request 5 without adjournment of the oral proceedings, since it would have required at least further clarification and investigation in order to assess whether it was credible that a skilled person following the teaching of D2 could have prepared an oil B having a hydroxyl number with the new range defined in claim 1 of auxiliary request 5. The fact that the filing of auxiliary request 5 constituted the last chance for the respondent to obtain maintenance of the patent, when there was no other justification for the late filling of this request, does not outweigh the need for fair proceedings and procedural economy.

8.3 On this basis, auxiliary request 5 is not admitted into the proceedings under Article 13(3) RPBA.

9. Documents D10 to D16 were cited in support of the appellant's objection that the claimed subject-matter lacked an inventive step. Having regard to the above negative finding in respect of inventive step, which is not based on documents D10 to D16, there is no need for the Board to address the admittance of these documents into the proceedings.