T 1207/21 18-03-2024

Summary of Facts and Submissions

I. Opponent 1 (appellant I), opponent 2 (appellant II) and opponent 3 (appellant III) lodged an appeal against the opposition division's decision rejecting the oppositions filed against European patent No. 3 141 374 (hereinafter: "the patent"), which is based on the European divisional application No. 16 193 166.2.

II. The patent proprietor (respondent) filed a reply to the appellants' statements of grounds of appeal, including claim sets according to auxiliary requests 1 and 2.

III. By letters dated 12 May 2022 and 17 April 2023, appellants I and III filed further submissions.

IV. In a communication under Article 15(1) RPBA issued on 30 January 2024, the board provided its preliminary opinion that, inter alia, there was a discrepancy between claim 1 of the respondent's auxiliary request 1 and the corresponding passages of its reply.

V. By letter dated 16 February 2024, the respondent filed further submissions including two claim sets entitled "Auxiliary Request 1 (corrected)" and "Auxiliary Request 2". In point 1 of that letter, it is stated:

"We maintain our Main Request (section 2) as well as Auxiliary Requests 1 and 2 (sections 3 and 4). In addition, we file herewith Corrected Auxiliary Requests 1 and 2 for the avoidance of any doubt about the patentee's requests filed with the Response to the Appeal."

VI. The following documents submitted during the first-instance proceedings are cited in this decision:

D1: |US 3,013,925 |

D18:|DE 23 48 607 C2|

VII. Oral proceedings before the board were held on 18 March 2024.

Appellants I, II and III requested that the decision under appeal be set aside and that the patent be revoked.

The respondent requested that the opponents' appeals be dismissed (main request) or, as an auxiliary measure, that the decision under appeal be set aside and that the patent be maintained as amended according to the claims of auxiliary request 1 or 2, both requests filed with the reply to the statements of grounds of appeal. In addition, the respondent requested that its auxiliary requests 1 and 2 be corrected under Rule 139 EPC.

VIII. Claim 1 as granted reads (the feature numbering used by the board is included in square brackets):

"[1] A method for welding profiled elements in plastic material, in particular PVC, comprising the steps of:

[2] - preparing at least two profiled elements (3; 3a, 3b; 60, 61), arranged with respective zones to be welded (4; 62, 63) facing one another;

[3] - making a groove (19) in correspondence to at least one zone to be welded (4; 62, 63) of the profiled elements (3; 3a, 3b; 60, 61), [4] said step of making the groove (19) being performed by means of a removal operation on a peripheral edge of at least one profiled element (3; 3a, 3b; 60, 61);

[5] - heating said zones to be welded (4; 62, 63);

[6] - coupling the zones to be welded (4; 62, 63) to one another, [7] pressing the profiled elements (3; 3a, 3b; 60, 61) one against the other so as to keep the zones to be welded (4; 62, 63) in reciprocal contact;

[8] - said step of coupling the zones to be welded (4; 62, 63) comprising a sub-step of melting the zones to be welded (4; 62, 63) into one another in order to define a welding bead and a sub-step of [9] making a containing compartment (19a) defined by said at least one groove (19); [10] said welding bead being made internally of said containing compartment (19a);

[11] characterised in that said step of coupling the zones to be welded (4; 62, 63) comprises the step of arranging a containing presser (27) in correspondence to said containing compartment (19a) for preventing exit of the welding bead from the compartment itself."

IX. Claim 1 of the respondent's auxiliary request 1 differs from claim 1 as granted in that the following feature 12 is included at the end of the claim:

"[12] wherein said removal creates a step of said peripheral edge, extending along the entire extension of the zone to be welded (4; 62, 63) of said profiled element (3; 3a, 3b; 60, 61)."

X. The correction of auxiliary request 1 requested by the respondent involves including the following feature 4.1 between features 4 and 5 in claim 1:

"[4.1] wherein the removal operation is by milling;"

XI. The parties made the following submissions.

(a) Patent as granted - Ground for opposition under Article 100(b) EPC

(i) Appellants

The patent did not disclose the invention defined in claim 1 as granted in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art. Paragraph [0064] of the patent not only disclosed that the purpose of the tools 21 was to shape the grooves 19 but that these were also fundamental for evening out the walls and correcting any cutting errors. In the absence of any such levelling, the zones to be welded would be too irregular and therefore not weldable. Claim 1 as granted, however, also covered embodiments in which no levelling was performed on the zones to be welded. The patent did not explain how the profiled elements could be successfully welded when no levelling was carried out, in spite of the zones to be welded being too irregular and therefore not weldable. The explanations in the patent itself gave rise to serious doubts that the skilled person could carry out the claimed invention. No recourse to the common general knowledge was necessary. The burden to prove that the invention was sufficiently disclosed had shifted to the respondent.

Feature 3 required the groove to be identical to the at least one zone to be welded of the profiled elements. In view of this claim interpretation, the invention defined in claim 1 as granted could not be carried out. Figures 4 and 5 of the patent showed that the groove was adjacent to the zone to be welded and not identical to it. Moreover, feature 3 contradicted feature 7, which implied that the groove was not identical to the zone to be welded.

(ii) Respondent

The patent disclosed the invention defined in claim 1 as granted in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art. Paragraph [0064] of the patent spoke about the purpose of the tools 21 in a preferred embodiment. This in itself did not teach anything about the subject-matter of claim 1 as granted, which was directed to a method. Dependent claim 7 of the patent indicated that the levelling step was optional. Levelling of cut profiled ends was known in the art and did not need to be performed necessarily when making the grooves. Even in the absence of a levelling step, the method of claim 1 could be carried out and lead to the advantages of the invention (smooth surface, no need for post-processing) even if more molten material was generated. If any, the only adaptation needed was sizing the groove to adapt to the amount of material, which was within the skilled person's capabilities.

The expression "in correspondence to" (see feature 3) was not a synonym of "coinciding". There was no suggestion of that interpretation in the patent. The skilled reader understood that the groove was made "at" the at least one zone to be welded. This understanding was supported by Figures 4 and 5 of the patent.

(b) Patent as granted - Ground for opposition under Article 100(a) in conjunction with Article 54 EPC

(i) Appellants

The subject-matter of claim 1 as granted was not new in view of document D1 or D18.

The term "peripheral edge" (see feature 4) merely meant "at the distal end of the profiled elements" and/or "in the zones to be welded". The method disclosed in document D1 used a reamer 38 to make chamfer-shaped grooves ("bevels") at 33 into the internal peripheral edges of the profiled elements 17, 24 (see document D1: Figures 2 and 4; column 3, lines 13, 14, 29 and 30). Document D1 thus disclosed feature 4. According to paragraph [0077] and Figure 8a of the patent, the groove 19 may be partially or entirely covered. Thus the groove did not have to be visible. Regarding feature 11, the method disclosed in document D1 provided that containing pressers ("die clamps" or "die molds" 16, 19) were arranged in correspondence to a containing compartment formed by the grooves ("bevels") in the opposing profiled elements 17, 24 to be welded (see document D1: column 3, lines 18 to 21). The term "in correspondence" did not necessarily mean that the containing pressers had to cover an opening of the containing compartment. It also encompassed embodiments in which the containing pressers were axially aligned with the containing compartment, regardless of whether the compartment opened to the outside or the inside of the profiled elements. This view was supported by paragraph [0105] and Figures 8a to c and 9a to d of the patent. In the embodiment shown in Figures 8a to c of the patent, it was the protrusion 31, not the containing presser, that delimited the containing compartment. Figures 7a and b and 9a to d of the patent showed that molten material exited on the inside of the profiles. Feature 11 therefore did not require that no molten material could escape at all. While the containing pressers 16, 19 disclosed in document D1 formed a recess 34 on the inside, the formation of that recess was also envisaged in paragraph [0045] of the patent. The containing pressers 16, 19 of document D1 were suitable for preventing the welding bead from exiting the compartment itself (see document D1: column 3, lines 24 to 28; column 4, lines 1 to 6). The recess 34 was filled with molten material during the pressing. This molten material would otherwise remain on the inner circumference and exit the recess. This was apparent from the following drawings:

FORMULA/TABLE/GRAPHIC

The drawing on the left showed modified containing pressers 16, 19. When the pipes 17, 24 were pressed together, all of the molten material flowed radially inwards and emerged from the groove 33. A welding bead was thus formed, which the patent intended to prevent. Therefore, the purpose and effect of the containing pressers in the drawing on the left was not to prevent welding beads. The drawing on the right, on the other hand, corresponded to Figure 3 of document D1 and showed exactly the opposite. The containing pressers 16, 19 were aligned with the bevels or grooves 33. When the pressers were pressed together, the molten material did not flow radially inwards to exit the groove 33, but radially outwards. The recess 34 provided in the die clamps 16, 19 received exactly that molten material which would otherwise form a welding bead (see document D1: column 3, lines 13 to 17; Figures 2 and 3). The term "substantially" in column 3, line 28 of document D1 was understood as referring to the normal process variations associated with the process disclosed in document D1. The object in document D1 was to avoid the formation of the welding bead. The containing pressers disclosed in document D1 thus served to prevent the welding bead from exiting the groove 33. Column 1, lines 12 to 14 of document D1 disclosed that an objectional bead was prevented from forming on the inside of a welded thermoplastic pipe. Whether a technical problem stated in the description of the patent was solved by the method disclosed in document D1 was not a relevant criterion for the assessment of novelty. In view of paragraph [0007] of the patent, feature 11 only required an aesthetically pleasing surface and not the avoidance of any welding bead at all.

Document D18 disclosed all the features of claim 1 as granted. Regarding feature 11, Figure 4d of document D18 showed that a rigid part 49, which served as a presser, pressed the bead 47 into the remaining recess 48. The rigid part 49 moved while the plastic material was still soft. This meant that this process step took place during the step of joining the zones to be welded. The fact that the bead 47 protruded above a wall surface for a short period did not contradict feature 11. No sequence was defined or claimed for the method steps in claim 1 as granted. Feature 11 merely specified that, at the end of the process, two profiles had been welded and a welding bead prevented. Claim 1 as granted did not specify that the welding bead was prevented from exiting at all times.

(ii) Respondent

The subject-matter of claim 1 as granted was new in view of document D1, which did not disclose features 4 and 11. In document D1, the bevels 33 (see document D1: Figure 2) formed on the cylindrical plastic tubes 17, 24 were not "peripheral" because they resided on the inner edge of the tube opening and not on the outer edge as required by the term "peripheral edge of the profiled element". Hence, feature 4 was not disclosed. The generally recognised meaning of the term "peripheral edge" was that of an edge forming the external boundary or surface of a body - in the present case an edge forming the external boundary of the profiled elements. The term "peripheral" meant "towards the periphery". The peripheral edges were the edges at the outside of the profile. Regarding paragraphs [0007] and [0015] of the patent, the problem addressed by the patent and the solution only related to the visible surface and, hence, the external edges of the profiles, namely the peripheral edges. The broadest technically sensible meaning of "peripheral", without any undue limitation by the description, was "at the outer bounds". In view of the detailed description of the embodiments in the patent, the grooves could only be formed on the external edges. It was there where they formed the containing compartment and took up the molten material, ready to co-operate with the containing presser to avoid material overflowing beyond the visible surface (see for example Figures 7a, b and 8a, b of the patent). This was the object of the invention. If the grooves were formed on the internal edges, then the containing compartment would be too, and it would not be possible to arrange a containing presser in correspondence to any such "internal" containing compartment in order to prevent the welding bead from exiting the compartment itself. Moreover, when considering the technical solution of the invention, the broadest technically sensible meaning was that the "peripheral edge" was on the outer surfaces of the profile and not at some inner surface. Unlike the claimed subject-matter, the device and method of document D1 did not prevent a welding bead from forming on the visible surface of the profile. Document D1 did not aim for an aesthetic outer appearance but aimed at reducing the inner bead which disturbed the flow of liquid through a tube and strengthening the welding bond by avoiding failure from notch sensitivity, which was relevant for a liquid-conveying conduit (see document D1: column 1, lines 39 to 45). A "peripheral" edge had to be an edge that at least had continuity with the outward bounds of the profile, i.e. the outer visible surfaces. The skilled person understood a peripheral edge as the edge that would remain visible.

In document D1, the die clamps 16 and 19 were positioned on the wrong side, not "in correspondence to said containing compartment" as required by feature 11. These die clamps were not intended to and could not prevent a welding bead from exiting the containing compartment. In document D1, there was no compartment formed by grooves and closed towards the outside as defined in paragraph [0082] of the patent. Feature 11 implied that no welding bead could exit at all. This followed from the object of the method stated in the patent as granted, which was that post-processing method steps could be avoided. In document D1, a small welding bead 37 was formed (see document D1: column 1, lines 48 and 49; column 2, lines 7 to 10; column 3, lines 23 to 28; column 4, lines 1 to 6; Figure 3). The reason why document D1 spoke only of "substantially" no bead on the inner side was that control was brought about by, for example, the amount of pipe protrusion through the clamps, how big the bevels were and how strongly the tubes were pressed together. This was a rather coarse adjustment. The formation of an internal bead could not positively be prevented. While the clamps 16, 19 affected the formation of a welding bead on the inside of the pipes, they could not prevent it. The die clamps 16, 19 did not anticipate feature 11 as they were not suitable for preventing the welding bead from exiting the compartment formed by bevels 33. Some material - even if just a little - still protruded and formed a bead 37. Column 1, lines 12 to 14 of document D1 referred to an "objectional bead". This did not mean that no bead was formed at all. For the fluid conducting system of document D1, it was not necessary to completely remove the bead; it just needed to be small. Document D1 did not provide a logical link between the clamps 16, 19 and the fact that "substantially no bevel" was formed. The clamps 16, 19 were provided with recesses 34 that took up material flowing outwards. The molten material flowed into the recess 34, forming a bead 36 on the outer visible surface of the tubes.

The subject-matter of claim 1 as granted was new in view of document D18, which did not disclose features 4, 9 and 11. As could be seen from the sequence of Figures 4a to d of document D18, when the walls 41 and 42 were pressed together, a bead 47 formed on the outside, protruding beyond the surface. This bead 47 was not prevented from exiting the compartment. The rigid part 49 was not arranged at the recess 48 during the coupling step but was only moved there later when the welding bead 47 protruded over the surface of the walls 41, 42. Its effect was to spread the bead 47 into the adjacent remaining recess 48. The rigid part 49 did not fulfil the functional definition of feature 11.

(c) The respondent's request for correction of its auxiliary request 1

(i) Respondent

It was obvious that there was a discrepancy between claim 1 of auxiliary request 1 filed with the reply and the corresponding passages of the reply. In its submissions on novelty, inventive step and Article 123(2) EPC, the respondent had consistently referred to the feature of the removal operation being by milling. The respondent's true intention had been clear from the start. It had also been clear what the error was and what the correction had to be. The delay in filing the request for correction was immaterial. The respondent only became aware of the discrepancy in question as a result of the board's communication under Article 15(1) RPBA.

(ii) Appellant III

The discrepancy between the claims of auxiliary request 1 filed with the respondent's reply and the corresponding passages of the reply had already been indicated in appellant III's letter dated 17 April 2023. The respondent had filed its request for correction with the letter dated 16 February 2024, i.e. with a considerable delay. However, a request for correction had to be filed without delay (see G 1/12, point 37 of the Reasons, and T 2058/18). The request for correction should thus be refused.

(d) The respondent's auxiliary request 1 filed with its reply to the statements of grounds of appeal

(i) Appellants

The respondent's auxiliary request 1 filed with its reply to the statements of grounds of appeal should not be admitted into the appeal proceedings under Article 13(2) RPBA. Maintaining this request in the oral proceedings before the board constituted an amendment to the respondent's appeal case within the meaning of Article 13(2) RPBA.

Claim 1 of auxiliary request 1 lacked clarity because the features of evening out the walls and correcting any cutting errors were missing. These features were essential. Auxiliary request 1 contained amendments taken from the description. The amendments were thus open to an examination of clarity in accordance with decision G 3/14. Claim 2 of auxiliary request 1 was not clear because it referred to the "preceding claims" (i.e. plural) while there was only a single preceding claim.

Article 123(2) EPC was violated in view of the expression "a step of said peripheral edge, extending along the entire extension of the zone to be welded (4; 62, 63) of said profiled element (3; 3a, 3b; 60, 61)" (see feature 12). On page 9, lines 21 to 28 of the divisional application as filed (see paragraph [0072] of the published divisional application), on which the patent in suit was based, the above feature was inextricably linked to the following features: the peripheral edges were defined by the head extremities of each profiled element; the groove had a substantially stepped conformation in square, i.e. shaped at 90 ; during the removal by milling step, the step was implemented of the retention of the shavings by means of the cutter tool 21 with helical shape and the axial suction which conveyed the removed shavings towards the inside of the chamber 29a. On page 10, lines 6 and 7 of the divisional application as filed (see paragraph [0076] of the published divisional application), feature 12 was inextricably linked to the feature that the groove had a stepped conformation in undercut. Claim 1 of auxiliary request 1 was thus the result of an unallowable intermediate generalisation. In claim 2 of the divisional application as filed, the terms "developing" and "whole development" were used. The skilled person understood this as defining that a groove was provided and then enlarged, which was different from feature 12 of claim 1 of auxiliary request 1.

Auxiliary request 1 did not meet the requirements of Article 123(3) EPC. Although the scope of claim 1 of auxiliary request 1 was smaller than that of claim 1 as granted, the scope of protection conferred by claim 1 of auxiliary request 1 had been shifted compared with claim 2 as granted.

Moreover, the subject-matter of claim 1 of auxiliary request 1 was not new and did not involve an inventive step.

(ii) Respondent

Auxiliary request 1 had already been filed in the opposition proceedings and had been maintained throughout the opposition and appeal proceedings. It thus formed part of the appeal proceedings.

Feature 12 had a basis in claim 2 and on page 9, lines 21 to 28 of the divisional application as filed (see claim 2 and paragraph [0072] of the published divisional application). To interpret claim 2 of the divisional application as filed, the skilled person would have turned to page 9, lines 21 to 28 of the divisional application as filed and would have understood that the term "developing" corresponded to "extending". The fact that the embodiment disclosed in the description comprised further features was irrelevant since these were not part of claim 2 of the divisional application as filed. The square mentioned in the cited passage referred to a stepped conformation. There was no inextricable link between feature 12 and a square shape of the step. The head extremities of the profiled elements mentioned in the cited passage corresponded to the zones to be welded.

The requirements of Article 123(3) EPC were met since auxiliary request 1 did not lead to an extension of the protection conferred by the patent.

The subject-matter of claim 1 of auxiliary request 1 was new and involved an inventive step.

(e) Remittal

Appellants I and III were in favour of a remittal because they considered an examination at two instances appropriate in the case in hand. Appellant II had no comments. The respondent argued against remittal for reasons of procedural economy, since all parties and the board had expressed their views on auxiliary request 1 with regard to novelty and inventive step; the opposition division had expressed its views on these issues in its communication annexed to the summons.