T 0028/20 11-02-2021

Reasons for the Decision

1. Admittance of D9a

Document D9a was submitted for the first time by the respondent in its rejoinder to the statement of grounds of appeal. The appellant did not raise any objection against the admittance of D9a, which was filed at the outset of the appeal proceedings. Further considering that D9a was relied upon by both parties, in particular during the oral proceedings, whereby both parties indicated that the disclosure of D9a - in English - was equivalent to the one of D9 - in German , and that D9a can therefore be considered as a translation of D9, which was already part of the opposition proceedings, D9a is also in the proceedings.

Main request

2. Sufficiency of disclosure

2.1 In order to meet the requirements of sufficiency of disclosure, an invention has to be disclosed in a manner sufficiently clear and complete for it to be carried out by the skilled person, without undue burden, on the basis of the information provided in the patent specification, if needed in combination with the skilled person's common general knowledge. This means in the present case that the skilled person should in particular be able to prepare a composition according to operative claim 1 or to use such a composition according to operative claim 8, both of which is contested by the appellant.

2.2 Regarding claim 1, the opposition division's conclusion according to which the requirements of sufficiency of disclosure were fulfilled (sections 8 and 4.2 of the reasons) is contested by the appellant for the reason that the skilled person would not have sufficient information in order to choose appropriately the "same" first polymer of the HMWA and second polymer of the LMWA as indicated in operative claim 1, in particular in view of the unclear definition of the wording "same polymer" and of the definition of base polymers 4 to 8 of the patent in suit, which could both serve either as HMWA or as LMWA depending on the weight average molecular weight (sections 5.11 to 5.14 of the statement of grounds of appeal).

2.2.1 In that respect, sufficiency of disclosure is to be assessed in view of the patent specification as a whole and not on the basis of the wording of the claims only. In the present case, although the definition of the first polymer of the HMWA and/or of the second polymer of the LMWA as indicated in operative claim 1 (e.g. "said (co)polymer comprising ... a first polymer and, optionally, ... a first copolymer...") may be unclear, it is agreed with the respondent that it is derivable from paragraph 18 and from the experimental part (paragraphs 108-111) of the patent specification that the skilled person wanting to prepare a composition according to operative claim 1 would understand the terms "first polymer" and "first copolymer", respectively "second polymer" and "second copolymer" indicated in operative claim 1 as meaning "first monomer" and "first comonomer", respectively "second monomer" and "second comonomer" (sections 2.8 to 2.11 of the rejoinder to the statement of grounds of appeal).

Also, no argument was put forward by the appellant to refute the conclusion of the opposition division in that respect, according to which the terms "first polymer" and "second polymer" according to operative claim 1 would be read as "first polymer unit" and "second polymer unit" (first paragraph of section 4.2 of the reasons of the decision).

Under these circumstances, it cannot be agreed with the appellant that the skilled person is not in the position to select appropriately the "same" first polymer of the HMWA and second polymer of the LMWA in order to prepare a composition according to operative claim 1.

2.3 Regarding claim 8, the appellant argued that there was a lack of sufficiency of disclosure related to the definition of the term "high Tg" as given therein.

2.3.1 Claim 8 is a use claim which is characterised by a combination of structural features related to the definition of the HMWA and LMWA materials which have to be mandatorily present, with the additional functional feature "to provide a high Tg melt blended composition or moulded polymer product", whereby there is no reason to consider that said functional feature is mandatorily implicitly satisfied by all the compositions falling under the structural definition of claim 8. Therefore, the question to be answered is whether or not the patent in suit, optionally in combination with common general knowledge, provides sufficient guidance how to achieve such "high Tg".

2.3.2 In that respect, both parties read the term "high Tg" on the basis of the definition of that term given in paragraph 87 of the patent in suit (statement of grounds of appeal: sections 5.4-5.10; sections 2.3-2.6 of the rejoinder).

However, the normal rule of claim construction is that the terms used in a claim should be given their broadest technically sensible meaning in the context of the claim in which they appear. In particular, if a term present in a claim has a clear, accepted, generic meaning, it may not be held to have a limited meaning in view of the description of the patent specification (Case Law of the Boards of Appeal of the European Patent Office, 9th edition, 2019, section II.A.6.3.1).

In the present case, it makes no doubt that the term "high Tg" refers to a usual property of polymers, namely glass transition temperature. Although the term "high" is a relative one, it only means that said feature will have to be read in its broadest - technically meaningful - sense. On this basis there is no reason to read the term "high Tg" as being limited in the sense of paragraph 87 of the patent in suit.

2.3.3 The objections raised by the appellant in sections 5.5-5.10 of the statement of grounds of appeal are closely related to the definition of "high Tg" according to paragraph 87 of the patent in suit. In view of the conclusion reached in section 2.3.2 above, these objections cannot succeed. In particular, the arguments of the appellant do not show that the skilled person would have any difficulty in providing "high Tg" melt blended compositions using two acrylic materials HMWA and LMWA as defined in operative claim 8. In addition, any objection related to the meaning of the term "high Tg" would be related to the definition of the scope of the claims, i.e. would be an issue of clarity (which, according to G 3/14, OJ EPO 2015, 102 cannot be addressed at the present stage since the feature at stake is already present, in the same context, in claim 8 as granted) rather than sufficiency of disclosure.

2.3.4 The appellant further argued that the selection of monomers to prepare both the HMWA and the LWMA defined in claim 8 so that they exhibit a "high Tg" according to operative claim 1 required an undue burden (section 5.6 of the statement of grounds of appeal). Also, the definition of that term was relative and it was not possible from the data of the patent in suit to distinguish between low and high Tg (sections 5.7-5.9 of the statement of grounds of appeal).

In the Board's view, these arguments are again related to the definition of the scope of the claims and constitute a possible issue of clarity rather than sufficiency of disclosure, as argued by the respondent (section 2.6 of the rejoinder to the statement of grounds of appeal).

2.4 In view of the above, the appellant's arguments provide no reason for the Board to overturn the opposition division's decision pursuant to Article 100(b) EPC.

3. Inventive step

3.1 Objections raised

3.1.1 In its statement of grounds of appeal, the appellant not only put forward an objection of lack of inventive step against the subject-matter of claim 1 of the main request starting from D9 as closest prior art - as during the opposition proceedings - but further argued that it lacked inventive step in view of D4 as closest prior art, in particular examples 4D-1 and 4D-2 thereof, in combination with common general knowledge or D9 (sections 6.18 to 6.20). The question of the admittance of that new objection was addressed in the Board's communication (section 7.5) and the respondent requested at the oral proceedings before the Board that said objection be not admitted.

3.1.2 In that respect, it was not contested by the appellant, in particular at the oral proceedings before the Board, that such an objection of lack of inventive step based on D4 as closest prior art was neither dealt with in the contested decision, nor that there were any reasons justifying the submission of said objection for the first time in the statement of grounds of appeal.

Under these circumstances, that objection does not fall under a party's appeal case as defined in Article 12(2) RPBA 2020 (since it is not directed to an objection on which the decision under appeal was based). Therefore it constitutes an amendment of the appellant's case in the sense of Article 12(4), first paragraph, RPBA 2020, whereby also the stipulations of Article 12(4) 2020, second paragraph are not satisfied, since the appellant has not explained why that objection was first raised in appeal.

In view of the above, the Board finds it appropriate to make use of its discretion pursuant to Article 12(4), first paragraph, second sentence, RPBA 2020 by not admitting into the proceedings the objection of lack of inventive step starting from D4 as closest prior art.

3.2 D9/D9a as closest prior art

3.2.1 During the current proceedings the arguments regarding inventive step were either based on document D9 (decision under appeal; statement of grounds of appeal) or D9a (rejoinder to the statement of grounds of appeal; both parties at the oral proceedings). In the present decision, following the common position of the parties that D9 and D9a are equivalent documents and in the absence of any evidence to the contrary, the assessment of inventive step will be made in respect of document D9. However, the same conclusions would be reached considering D9a.

3.2.2 D9 as closest prior art

Both parties agreed with the opposition division's conclusion according to which D9 constitutes a suitable closest prior art document. There is no reason for the Board to deviate from that view.

In that respect, D9 (claim 1) deals with an impact-strength-modified polymethacrylate moulding compound, characterized by a Vicat softening temperature per ISO 306 (B 50) of at least 90°C, a notched impact strength (Charpy) per ISO 179/1eA of at least 3.0 kJ/m**(2) at 23°C, and a melt volume-flow rate MVR (230°C/3.8 kg) per ISO 1133 of at least 11 cm**(3)/10 min, obtained by mixing, in the melt,

a) 80 to 98 wt% of an impact-strength-modified polymethacrylate moulding compound with

b) 20 to 2 wt% of a low molecular weight polymethacrylate moulding compound,

the impact-resistant moulding compound comprising 70 to 99 wt.% of a matrix of 80 to 100 wt.% of radical-polymerized methyl methacrylate units and if necessary 0 to 20 wt.% of further comonomers that can undergo radical polymerization, and containing 1 to 30 wt.% of an impact-strength modifier,

and the low molecular weight polymethacrylate molding compound comprising 80 to 100 wt.% of radical-polymerised methyl methacrylate units and 0 to 20 wt.% of further comonomers that can undergo radical polymerisation, and having a viscosity number (etasp/c) of 25 to 35 ml/g as measured in chloroform per ISO 1628 Part 6.

In particular, the examples of D9 (pages 9-11) disclose the preparation of samples by injection-moulding of a composition comprising:

- an impact-strength modified moulding composition comprising 92.5 wt.% of a matrix polymer and 7.5 wt.% of a core-shell impact modifier, whereby the matrix polymer is made of 91 wt.% methyl methacrylate and 9 wt.% methyl acrylate;

- an amount of either 0, 5 or 10 wt.% of a low molecular weight moulding compound comprising 85 wt.% methyl methacrylate and 15 wt.% methyl acrylate units with a weight average molecular weight of about 50,000 g/mol.

In view of the above, the examples of D9 carried out with 5 wt.% and 10 wt.% low molecular weight moulding compound constitute a particularly appropriate starting point for the analysis of the inventive step.

3.3 Distinguishing feature(s) over D9

3.3.1 It was undisputed by the parties that the subject-matter of operative claim 1 differs from the compositions prepared in the examples of D9 carried out with 5 wt.% and 10 wt.% low molecular weight moulding compound in that it comprises a higher amount of impact-modifier (30-50 wt.%), in particular an amount which is even higher than the maximum amount taught in D9 (29.4 wt.%, as derivable from claim 1 thereof).

3.3.2 However, the parties disagreed whether or not the following features specified in operative claim 1 were effectively satisfied by the examples of D9 carried out with either 5 wt.% or 10 wt.% of low molecular weight moulding compound:

(a) The requirement in terms of the molecular weight of the HMWA component, which should be between 40k Daltons and 1000k Daltons and above the one of the LMWA component;

(b) The requirement in terms of the molecular weight of the LMWA component, which should be between the entanglement molecular weight Me and 250k Daltons.

3.3.3 Regarding above feature (a)

It is correct that no explicit disclosure in respect of the molecular weight of the matrix polymer used to prepare the impact-strength modified moulding composition is provided in D9.

However, in the Board's view, the skilled person would understand the disclosure of D9 as a whole as implying that the molecular weight of the impact modified polymer matrix should be higher than the one of the so-called low molecular weight polymethacrylate moulding compound. Firstly, the terminology used in D9 to indicate the second component (low molecular weight) implies that it has a lower molecular weight than the matrix. Secondly, the only ranges of molecular weight for the matrix indicated in D9 (90.000 to 200.000 g/mol, preferred 100.000 to 150.000 g/mol, page 4, lines 9-11), albeit as a preferred feature, provide values which are all largely above the molecular weight of the low molecular weight component indicated in the general disclosure (30.000 to 70.000 g/mol, in particular 40.000 to 60.000 g/mol, page 7, lines 2-3) and in the examples of D9 (50 000 g/mol, i.e. 50k Daltons). On top of that, the fact that in the examples of D9 the addition of the low molecular weight component leads to an increase in the melt flow rate of the impact modified polymer composition (D9: table on page 11) confirms that the impact modified polymer matrix must have a higher weight average molecular weight than the low molecular weight component, as put forward by the appellant during the oral proceedings before the Board. Therefore, it is derivable from D9 as a whole that the polymethacrylate matrix used in the examples of D9 implicitly, but directly and unambiguously, has a weight average molecular weight higher than 50k Daltons, which is both above 40k Dalton and higher than the molecular weight of the low molecular weight polymer component used therein, as required by claim 1 of the main request.

In addition, it was not objected to by the respondent that the impact modified polymethacrylate matrix used in the examples of D9 could not have a weight average molecular weight above 1000k Daltons, as also specified in claim 1 of the main request. The Board has also no reason to deviate from that view, in particular because there is no reason to expect that that requirement would not be met in view of the very high value of the higher limit of the range of molecular weight indicated in claim 1 (1000k Daltons) and taking into account the preferred values indicated in D9 (90.000 to 200.000 g/mol, preferred 100.000 to 150.000 g/mol, page 4, lines 9-11).

For these reasons, the requirement in terms of the molecular weight of the HMWA component specified in claim 1 of the main request does not constitute a distinguishing feature over the examples of D9 carried out with either 5 wt.% or 10 wt.% of the low molecular weight moulding compound.

3.3.4 Regarding above feature (b)

The component of D9 corresponding to the LMWA material defined in operative claim 1 is the low molecular weight polymethacrylate disclosed therein, which in the examples of D9 is a copolymer of 85 wt% methylmethacrylate and 15 wt.% methyl acrylate having a weight average molecular weight of 50 000 g/mol (D9: page 10, last paragraph). Although it is correct that there is no information in D9 if said molecular weight is above the entanglement molecular weight Me, the question to be answered is if said requirement is implicitly satisfied, as put forward by the appellant in view of the information provided in the patent in suit in respect of said feature Me (statement of grounds of appeal: sections 6.8-6.9). In this respect the molecular weight of the low molecular weight moulding compound disclosed in the examples of D9 (50 000 g/mol) is not only according to all preferred embodiments indicated in paragraph 46 of the patent in suit, but also much higher than the molecular weight of the low molecular weight component used in the examples of the patent in suit (see "base polymer 3" in paragraph 106, with a weight average molecular weight of 22.1k Daltons). Taking into account in addition the similarity of the copolymers in the examples of D9 and of the patent in suit, the Board finds it not credible that the molecular weight of the low molecular weight component in the examples of D9 may be below the entanglement molecular weight Me. Although that issue was mentioned in the Board's communication (section 7.5.3), no argument or evidence was provided by the respondent to show that there were any reason to consider that the low molecular weight component used in the examples of D9, in particular characterised in that it has a weight average molecular weight of 50 k Daltons, may not have satisfied the Me requirement defined in claim 1 of the main request. Under these circumstances, the Board holds that the requirement in terms of the molecular weight of the LMWA component specified in operative claim 1 is implicitly satisfied in the examples of D9.

For these reasons, the requirement in terms of molecular weight of the LMWA component specified in claim 1 of the main request does not constitute a distinguishing feature over the examples of D9 carried out with either 5 wt.% or 10 wt.% of the low molecular weight moulding compound.

3.3.5 In view of sections 3.3.1, 3.3.3 and 3.3.4 above, the subject-matter of claim 1 of the main request only differs from the examples of D9 carried out with either 5 wt.% or 10 wt.% of the low molecular weight moulding compound in that it requires the presence of a higher amount of impact-modifier, as already concluded by the opposition division.

3.4 Problem effectively solved over the closest prior art

During the oral proceedings before the Board, both parties agreed with the findings of the opposition division that the problem effectively solved over the examples of D9 carried out with either 5 wt.% or 10 wt.% of the low molecular weight moulding compound resided in the provision of an alternative impact-modified acrylic polymer composition with good processability, thermal resistance and impact properties. The Board has no reason to deviate from that view, in particular because there is no evidence on file in support of a fair comparison between the subject-matter being claimed and the above identified closest prior art, i.e. it was not shown that the above indicated distinguishing feature is related to any technical effect. In that respect, it was in particular clarified at the oral proceedings that the improvement relied upon by the respondent in writing (letter of 11 January 2021: sections 3.7 and 3.8; see in particular Figure 4 of the patent in suit) was based on the comparison of compositions as claimed with compositions which do not illustrate the teaching of the closest prior art D9/D9a and are not related to the above indicated distinguishing feature (higher amount of impact modifier). Rather, the improvements claimed to be achieved (both in the patent in suit and in the respondent's letter of 11 January 2021) by the compositions claimed are discussed with respect to compositions comprising only HMWA copolymers having similar molecular weight but comprising higher levels of acrylate commoners (as indicated in paragraph 86 of the patent in suit).

3.5 Obviousness

3.5.1 The question has to be answered whether the skilled person, desiring to solve the problem indicated 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.

3.5.2 In that respect, it was undisputed by the parties that the most general teaching of D9 is that the impact-modifier may be used in an amount of up to 29.4 wt.% (as derivable from e.g. claim 1 of D9). Therefore, it makes no doubt that D9 alone would at least render obvious to solve the problem defined in above section 3.4 by increasing the amount of impact-modifier up to that value.

3.5.3 It remains to be assessed whether the skilled person aiming at solving that problem would contemplate using even higher amounts of impact-modifier, in particular amounts in the range of 30-50% w/w as defined in claim 1 of the main request.

a) In that respect, it is first noted that while D9 indeed discloses a maximum amount of 29.4 wt.% impact-modifier, it contains no teaching not to use higher amounts thereof or no disclosure that would prevent the skilled person from doing so.

b) The respondent and the opposition division both argued that the skilled person would not increase the amount of impact-modifier because it was unpredictable how the properties of the whole composition would be affected, in particular taking into account that the compositions prepared in D9 were a complex chemical system.

However, the established decisive principle governing the answer to the question as to what a person skilled in the art would have done depends on the result he wished to obtain (T 939/92, OJ EPO 1996, 309: point 2.5.3 of the reasons). In the case in hand, it must therefore be considered that the skilled person is deemed to be merely seeking to provide further impact-modified compositions in alternative to the ones of D9 but is not wishing to necessarily keep all properties obtained with the compositions of the examples of D9 at the same level. Thus, the skilled person would consider an increase in the amount of impact-modifier even in amounts higher than the ones taught in D9 as a useful and obvious measure, in particular to further increase the impact resistance of the compositions so prepared. In doing so, the skilled person would be merely accepting possible disadvantages (which were not demonstrated in the present case but only alleged, both by the opposition division and the respondent) related to the use of higher amounts of impact modifiers. In that respect, it is further noted that it is not credible to the Board that increasing the amount of impact-modifier from a maximum of 29.4 wt.% as taught in D9 to a slightly higher amount of 30 wt.% as defined in claim 1 of the main request may be expected to lead to so dramatic changes in the properties of the composition that the skilled person would be deterred from using such an amount of impact modifier.

In the Board's view, the fact that D9 indeed discloses that the preferred range of impact modifier is far removed from the upper end disclosed therein and that a rather low amount of impact modifier is used in the examples of D9, as argued by the opposition division and the respondent, does not affect the above conclusion because the problem to be solved is, as indicated above, to provide a mere alternative to the closest prior art. Therefore, these arguments are rejected.

For these reasons, the arguments put forward by the respondent and those retained by the opposition division are not persuasive.

c) In view of the above and in particular in the absence of any effect related to an amount of impact-modifier in the range of 30-50% w/w as indicated in claim 1 of the main request, said feature can only be seen as being arbitrary. Therefore, it would be obvious for the skilled person aiming at providing an alternative composition to the ones of the closest prior art defined above to increase the amount of impact-modifiers to an amount in the range of 30-50% w/w, thereby arriving at the subject-matter of claim 1 of the main request.

3.6 In view of the above, the subject-matter of claim 1 of the main request is not inventive in view of D9 as closest prior art and the main request is not allowable.

Auxiliary request 1

4. Article 123(2) EPC

4.1 The appellant argued that subject-matter defined in the claims of auxiliary request 1 could only be arrived at after combining passages of the application as filed which were related to the first aspect and the third aspect of the invention, which amounted to making a choice from two different lists.

4.2 However, the application as filed when discussing these embodiments defined as "aspects of the present invention", disclosed in particular:

- An acrylic polymeric composition comprising a melt blend of thermoplastic HMWA and LMWA components as defined in the paragraph bridging pages 4 and 5 of D1 ("first aspect");

- An impact modified acrylic polymer composition comprising a base polymer in accordance with the acrylic polymeric compositions according to the first aspect and a core-shell impact modifier (application as filed: page 16, lines 15-21; "third aspect").

Under these circumstances, the combination of the first and third aspects of the invention is directly and unambiguously derivable from the application as filed and does not amount to a choice from different lists. Therefore, the appellant's objection pursuant to Article 123(2) EPC is rejected.

5. The appellant confirmed at the oral proceedings before the board that no other objections were present against auxiliary request 1 (see section XI f) above). Since the sole objection put forward by the appellant in respect of auxiliary request 1 is not successful, the decision under appeal is to be set aside and the patent is to be maintained in amended form on the basis of the claims of said auxiliary request 1, after any consequential amendment of the description.