T 1654/13 (Dilution-thickening surfactant system / UNILEVER) 27-01-2015

Admissibility of the appeal

1. The notice of appeal was filed by the then common representative of the two joint patent proprietors Unilever N.V. and Unilever PLC, indicated on the patent in suit and in the (online) Register (at the time of filing the appeal), i.e. Mr Rosen Jacobson, "on behalf of the patent proprietor, Unilever N.V.".

1.1 In the letter of 4 December 2014 (see point VIII above) it was submitted that the appeal filed by the common representative of the joint patent proprietors had to be understood as having been filed on behalf of both patent proprietors as joint appellants. The wording used in the notice of appeal, referring to only the first one of the two patent proprietors, i.e. Unilever N.V., had thus to be understood in relation to the request for the reduction of the appeal fee only.

1.2 The Board firstly remarks that according to

Article 118 EPC (Unity of the European patent application or European patent) proprietors of a European patent who are not the same in respect of different designated Contracting States shall be regarded as joint proprietors for the purposes of proceedings before the EPO.

This applies in the present case to the joint proprietors Unilever N.V. and Unilever PLC.

1.3 Secondly, the principle that a plurality of legal or natural persons can only act jointly as a single party (a "group party"), and the requirement that such a group party has to act through a common representative, were endorsed by the Enlarged Board of Appeal with respect to proceedings before the Boards of Appeal in decision R 18/09 of 27 September 2010 (see points 4 to 7 of the reasons) with respect to a petition for review originally filed by and on behalf of only one of the three joint patent proprietors. Attention is drawn in this respect in particular to the following passage of decision R 18/09 (see Reasons, point 5; emphasis added): "[t]he Enlarged Board of Appeal held in decision G 3/99 (OJ EPO 2002, 347) that an opposition filed by several persons in common is to be dealt with as an opposition filed by only one party and such a group of common opponents is to be considered as a single party represented by a common representative (see Reasons, point 15). It further held that, if such a group of common opponents should file an appeal, they can only do so jointly as a single party acting through their common representative (see Reasons, point 17). The same principle has been applied to the filing of an appeal by one of the joint proprietors (see T 1154/06 of 9 December 2008, Reasons, point 1)."

Said principle was also considered and found to be respected in decision T 1366/04 of 16 April 2008 (see point 1.3 of the reasons, last paragraph). In said case the appeal had been filed by the first one of two joint patent proprietors only. The Board entrusted with the case held that the requirements of Article 118 EPC were met and that there was no doubt about the identity and appellant status of the two patent proprietors, since the appeal had been filed by the patent proprietor mentioned first on the patent in suit, who had acted as the common representative pursuant to Rule 100(1) EPC 1973.

1.4 Considering the submission of the Appellant mentioned under point 1.1 supra, the Board therefore accepts that in the present case, in the absence of an express indication to the contrary in the notice of appeal, the appeal was indeed intended to be filed on behalf of the two joint patent proprietors. Hence, there is no doubt that Unilever N.V. and Unilever PLC are joint appellants in the present case.

1.5 Consequently, the appeal is admissible (Article 108 and Rule 99(1)a) EPC).

Admissibility of the Appellant's auxiliary request

2. The Appellant filed with its statement of grounds a new set of amended claims 1 to 8 labelled 3**(rd) auxiliary request. This set of claims differs from the set of claims as granted substantially only in that granted claims 9 and 10 are deleted.

2.1 For the Board, the filing of this request thus represents an attempt to overcome one of the reasons for the revocation of the patent. The deletion of claim 9 (and of claim 10 referring back to this claim), the subject-matter of which had been found to lack inventive step (see point IV above), can be considered as a direct reaction to the reasoning given in the appealed decision. Moreover, the deletion of said claims raised no new, let alone complex issues, since the remaining independent claims had already been debated in the first instance proceedings.

2.2 The claims according to the new auxiliary request filed at the oral proceedings are identical to those according to said 3**(rd) auxiliary request apart from some straight-forward amendments (see point X above and point 5 infra).

2.3 Said new auxiliary request thus did not raise any further complex issues and its late filing was also not objected to by the Respondent.

2.4 Therefore, the Board decided to admit this request into the proceedings despite its late filing (Articles 114(2) EPC and 13(3) RPBA).

Admissibility of the Appellant's experimental report

3. An experimental report labelled "Annex - Additional example" was submitted together with the statement of grounds of appeal.

3.1 The filing of this experimental report merely constitutes an additional attempt of the Appellant to corroborate its position that the claimed subject-matter was indeed an improvement, compared to the compositions according to the closest prior art. The report can be considered as a reaction to the findings of the Opposition Division, which did not accept that such an improvement had been proven (see page 6, point 1.3.2, sixth full paragraph of the decision reading "In the absence of any surprising effect the objective technical problem, starting from D1, is considered to be the provision of a further dilution-thickening system.").

3.2 The Respondent did not object to the late filing of said experimental report either.

3.3 Hence, the Board decided to admit this experimental report into the proceedings despite its late filing (Articles 114(2) EPC and 12(2),(4) RPBA).

Main request (patent as granted)

4. Inventive step - Claim 9

4.1 The invention

4.1.1 The invention concerns a dilution-thickening surfactant system.

4.1.2 As can be gathered from the description of the patent in suit (paragraphs [0017]) the dilution-thickening surfactant system of the invention is supposed to be more economical in use and suitable for being advantageously incorporated into cleaning compositions (paragraphs [0012] to [0016]), thereby providing an "enhanced retention of its cleaning agents (such as surfactants) in a carrier when being diluted".

4.2 Closest prior art

4.2.1 It is common ground between the parties that document D1 represents the closest prior art.

4.2.2 Considering that D1, as the patent in suit, relates to dilution-thickening surfactant systems, comprising similar surfactant components, to assist retention of a cleaning composition in a carrier (page 2, lines 28 to 30; page 4, lines 8 to 10; page 8, lines 10 to 14; page 11, line 30, to page 12, line 14), the Board has no reason to take another stance.

4.3 Technical problem solved according to the Appellant

The Appellant held that (see point XII above), starting from D1 as the closest prior art, the objective technical problem solved by the invention, was not merely the provision of a further dilution-thickening system providing high viscosity upon dilution, as exposed in point 1.3.1 of the decision under appeal. The experimental results submitted with the grounds of appeal showed that the technical problem solved was indeed the provision of a cleaning composition having enhanced retention in a carrier and/or high viscosity upon dilution such that controlled release, and thus efficient use, of the composition is obtained.

4.4 Solution

As a solution to this technical problem, the patent in suit proposes the ternary surfactant system according to claim 9, which is characterised in that it comprises specified amounts of three specific surfactant components, namely

"(a) 40-85%w Alkyl ether sulphate (0-4 EO)

(b) 0.01-50%w Linear alkylbenzene sulphonate

(c) 0.01-55%w Betaine;

adding up to 100%."

4.5 Alleged success of the solution

4.5.1 The Board remarks that according to the experimental data filed with the grounds of appeal a cleaning composition no. 1 (according to claim 1 at issue), comprising the three surfactants ethoxylated alkyl ether sulphate (AES hereinafter), LAS and betaine (i.e. a surfactant system according to claim 9 at issue) and, additionally, Magnesium Sulphate-7H2O as electrolyte, is compared with similar compositions A to E containing only two out of said three surfactants.

4.5.2 Therefore, in the Board's judgement, for reasons analogous to those expressed in point 1.3.1 of the decision under appeal (see point IV above) with respect to the comparative data contained in the patent in suit, the Appellant's new experimental data do not convincingly show any specific effect or improvement attributable to the use of a ternary surfactant system according to claim 9, but not comprising electrolyte, instead of a comparable binary surfactant system.

4.6 Reformulation of the technical problem

Hence, the Board has no reason to call into question the finding of the Opposition Division exposed in point 1.3.1 of the decision under appeal, that starting from D1, the technical problem must be formulated in a less ambitious manner, i.e. as the provision of a further dilution-thickening surfactant system providing high viscosity upon dilution.

4.7 Success of the solution

In view of paragraph [0023] of the description and the diagram of figure 1 of the patent in suit, the Board has no reason to doubt that the ternary surfactant system of claim 9 solves said less ambitious technical problem.

4.8 Obviousness of the solution

4.8.1 It remains thus to be evaluated whether providing a ternary surfactant system as defined in claim 9 was obvious to the skilled person in the light of the state of the art.

4.8.2 The only argument submitted by the Appellant in this respect (see point XII above) was that D1 did not suggest in any way to use a three-surfactant system according to the contested patent when faced with the technical problem of providing a cleaning composition having enhanced retention in a carrier upon dilution with water such that controlled release, and thus efficient use, of the composition is obtained.

4.8.3 However, the Board notes that this argument does not concern the less ambitious technical problem actually solved by the surfactant system according to claim 9.

Hence the Board has no reason to overturn the finding of the Opposition Division that it was obvious for the skilled person, in the light of the teaching of document D1, to provide a combination of three surfactants according to claim 9 as granted.

4.8.4 More particularly, D1 discloses preferred surfactant systems which thicken when diluted with water and contain one or more surfactants of AES, lauryl sulphate and betaine (page 8, lines 12 to 14). Moreover, D1 explicitly suggests that "it is possible to use other anionic surfactant in combination with ... the ether sulphate surface active agent" (page 8, lines 31 to 33), one of the two preferred additional anionic surfactants being alkyl benzene sulphonate (page 9, lines 17 to 19), i.e. the class of surfactants including the well known LAS. A surfactant system comprising such a combination of AES and alkyl benzene sulphonate surfactants is used in the preferred cleaning composition exemplified on page 17, lines 1 to 8, of D1, whilst the particularly preferred cleaning composition exemplified in the following paragraph of D1 contains the preferred mixture of an AES and a betaine.

Therefore, in the Board's judgement, it was indeed obvious for the skilled person, seeking to solve the technical problem (point 4.6 supra) and taking into account the teaching of page 8 of D1 referred to supra, to try the readily available option of combining the two anionic surfactants used in the preferred formulation described on page 17, lines 1 to 8, of D1, for example a C8-C18 alkyl ether sulphate and LAS, with betaine as a third surfactant component.

4.8.5 Document D1 moreover generally teaches to use typically 2 to 30% of AES (page 8, lines 24 to 25), 10 to 30% alkyl benzene sulphonate (page 9, lines 25 to 26) and 0.5 to 5% betaine (page 11, lines 8 to 9), all percentages being by weight of the fully formulated compositions.

Expressed in percentages by weight based on the ternary surfactant system only, the corresponding individual, relative surfactant concentrations will be higher (to add up to 100%) and will necessarily overlap with the broad ranges of claim 9 at issue (40-85% AES, 0.01-50% LAS and 0.01-55% by weight betaine).

As already held in the decision under appeal (point 1.3.1, penultimate sentence), the skilled person would thus readily consider operating in these ranges.

4.8.6 In the Board's judgement, the skilled person seeking to provide an alternative dilution thickening surfactant system and merely following the general teaching of document D1 would thus obviously try, according to one of several approaches readily available to him, ternary surfactant systems comprising AES, LAS and betaine in relative amounts being such that the resulting systems fall within the scope of claim 9 as granted.

4.9 The Board thus concludes that the subject-matter of claim 9 at issue lacks an inventive step (Articles 52(1) and 56 EPC).

4.10 Hence, the main request is not allowable.

Auxiliary request

5. Allowability of the amendments

5.1 The replacement of "215**(-1)" by "21**()s**(-1)" in claim 1 (see point X above) is nothing more than the correction of an obvious typing error and finds basis in the application as filed (published as WO 2008/074667 A1) see e.g. page 6, line 30.

5.2 In claims 2 to 4 further typing errors were removed and claim 7 was deleted altogether, with consequential renumbering of claim 8 and adaptation of the back-reference to the preceding claims contained therein.

5.3 The allowability of these amendments was not contested by the Respondent.

5.4 The Board is also satisfied that the amendments made are not objectionable under Article 123(2) EPC.

6. Inventive step - Claim 1

6.1 The invention

6.1.1 The invention concerns a dilution-thickening aqueous liquid cleaning composition comprising a dilution-thickening surfactant system (see claim 1) and a method to clean hard surfaces involving the use of said composition (see claim 7).

As indicated in the description (paragraphs [0012] to [0016]) cleaning compositions according to the invention are supposed to have enhanced retention in a carrier and/or high viscosity upon dilution, even at high dilution rates, which enhanced retention in the carrier provides controlled release of the composition.

6.2 Closest prior art

6.2.1 D1 relates to a dilution-thickening composition containing a surfactant system to assist retention of the cleaning composition in a carrier (see page 4, lines 8 to 10; page 8, lines 9 to 13; page 11, line 22 to page 12, line 14). It discloses inter alia a composition which contains the two surfactant components AES and alkyl benzene sulphonate, as well as an electrolyte (D1, page 17, lines 1 to 8).

6.2.2 Therefore, it was common ground between the parties that document D1, and in particular the preferred composition disclosed on page 17, lines 1 to 8, represents the closest prior art. The Board has no reason to take another stance.

6.3 Technical problem

The Appellant submitted during oral proceedings that the technical problem solved by the invention consisted in the provision of an improved cleaning composition showing an enhanced retention in a carrier and higher viscosity on dilution with water so that better controlled release and efficient use of the composition is obtained.

6.4 Solution

As the solution to this technical problem, the patent in suit proposes the composition according to claim 1 at issue, which is characterised in particular in that it contains specific amounts of a specific ternary surfactant system and of a specific electrolyte, and in that it has an initial viscosity within a specific range, more particularly (emphasis added by the Board)

"(a) 5-50%w of dilution-thickening surfactant system comprising:

(i)40-85%w Alkyl ether sulphate (0-4 EO);

(ii)0.01-50%w Linear alkylbenzene sulphonate; and

(iii)0.01-55%w Betaine;

adding up to 100%,

and wherein the composition further comprises

(b) 2.5-7.5%w of an electrolyte, selected from water-soluble organic and inorganic salts other than anionic surfactants, wherein the cation is chosen from alkali metals, alkaline earth metals, ammonium and mixtures thereof and the anion is chosen from chloride, sulfate, phosphate, acetate, nitrate and mixtures thereof;

and wherein the initial viscosity of the composition is 800-1250 mPa.s, wherein the viscosity is determined at 25ºC, using a Haake VT550/VT500 viscometer at 21 s**(-1) with an MVII spindle."

6.5 Success of the solution

6.5.1 The experimental report filed by the Appellant with its statement of grounds contains a comparison

- of a composition no. 1 according to claim 1 at issue containing the ternary surfactant system AES/LAS/betaine and Magnesium Sulphate-7H2O as electrolyte

- with compositions A to E, each containing a merely binary surfactant system of AES/betaine, LAS/betaine, AES/betaine, LAS/betaine and AES/LAS, respectively.

The comparative compositions differ from composition no. 1 insofar as they comprise only two surfactant components in concentrations which are either the same (compositions A, B and E) or different (compositions C and D) compared to composition no. 1.

6.5.2 Even though none of the comparative compositions A to E reproduces exactly the composition of D1 (page 17, lines 1 to 8) which is the closest prior art, the compositions A, C and E represent compositions falling within the teaching of document D1, which inter alia identifies AES as a most preferred surfactant (page 8, lines 16 to 22). Moreover, composition A falls within the definition of another preferred composition of D1 (described on page 17, lines 10 to 16).

6.5.3 For the Board, these tests thus constitute a fair comparison with the compositions of the type disclosed in document D1.

It can be deduced therefrom that only the composition no. 1 according to the invention has an initial viscosity (1000 mPa.s) as required by claim 1 at issue. It is plausible that such a viscosity contributes to an easy impregnation and good retention of the composition in a carrier.

The comparative compositions A to E, respectively, show instead viscosities (Gel, 5, 5, 420, 3600 mPa.s, respectively) which are outside the claimed range of 800 to 1250 mPa.s. The Board remarks also, in this respect, that even if the viscosities have been measured in this report at a shear rate of 20 s**(-1) instead of 21 s**(-1) as required by claim 1, the viscosities of such compositions measured at 21 s**(-1) would be very similar. Therefore, the viscosity of the composition no. 1 would be within the range of 800 to 1250 mPa.s, while those of the compositions A to E would be outside this range. For the Board, the slightly different shear rate used in the viscosity measurements does not call into question the significance of the comparative tests. This was also not argued by the Respondent.

6.5.4 The tests also show that composition no. 1 has a viscosity profile wherein a viscosity peak of 4350 mPa.s is reached upon dilution at 60% concentration in water whilst by further dilution the viscosity is gradually reduced again. Instead, comparative compositions A, D and E do not show any increase of viscosity upon dilution but a steady decrease of the viscosity. Composition B shows an increase upon dilution from 5 to 50 mPa.s, which value does not change upon further dilution and is very much lower than the initial viscosity required in claim 1 at issue. Composition C shows a thickening from the initial viscosity of 5 mPa.s to a gel consistency at 70% concentration in water and a reduction of the viscosity upon further dilution. This viscosity profile is very different from that of the composition according to claim 1 at issue which starts from a much higher initial viscosity and involves a thickening upon dilution which does not lead to gel formation, and thus credibly results in an enhanced retention in a carrier and a better controlled release and efficient use of the composition.

6.5.5 Moreover, even though these tests concern only one composition according to claim 1 at issue, the Board accepts as plausible, in the absence of evidence to the contrary, that similar results will be achieved throughout the whole range of compositions claimed according to claim 1.

6.5.6 For the Board, the stated technical problem (point 6.3 supra) is thus convincingly solved by the composition according to claim 1 at issue.

6.6 Non-obviousness of the solution

6.6.1 Firstly, the Board remarks that document D1 does not contain any teaching concerning a desirable initial viscosity of the compositions disclosed therein.

6.6.2 Secondly, there is no suggestion in D1 that the use of a ternary surfactant system as defined in claim 1 (components and relative amounts) in combination with electrolyte could bring about any advantage in terms of the viscosity profile of the composition upon dilution, with a consequential better controlled release and efficient use of the composition.

6.6.3 In fact, document D1 (page 4, lines 9 to 21 and page 5, lines 1 to 9) suggests instead the use of a particular carrier, namely a sponge body containing a pouch, for obtaining a better controlled release of the composition. D1 is not concerned with results obtainable by combining specifically three surfactants with an electrolyte.

6.6.4 Therefore, even assuming that the skilled person could have been induced by the teaching of document D1 to try ternary surfactant systems instead of binary ones (see point 4.8.3 above), and could have tried to modify in this sense the preferred composition listed on page 17 of D1, he would not have done it with the expectation of achieving any advantage in terms of enhanced retention in a carrier and higher viscosity on dilution with water, resulting in a better controlled release and efficient use of the composition.

6.6.5 For the Board, the prior art invoked by the Respondent does not contain any teaching that, without the benefit of hindsight, would actually induce the skilled person to modify the preferred composition of D1 such as to arrive at a composition according to claim 1 at issue with the expectation of solving the above mentioned technical problem.

6.6.6 The Board thus concludes that the compositions according to claim 1, and claims 2 to 6 dependent thereon, as well as the method according to claim 7 making use of such compositions, involve an inventive step (Articles 52(1) and 56 EPC).