T 0657/96 () of 29.4.1998

European Case Law Identifier: ECLI:EP:BA:1998:T065796.19980429
Date of decision: 29 April 1998
Case number: T 0657/96
Application number: 91900961.3
IPC class: G03H 1/02
B29C 59/00
Language of proceedings: EN
Distribution: C
Download and more information:
Decision text in EN (PDF, 1007.068K)
Documentation of the appeal procedure can be found in the Register
Bibliographic information is available in: EN
Versions: Unpublished
Title of application: Method for embossing holograms
Applicant name: Koninklijke Emballage Industrie Van Leer B.V.
Opponent name: Giesecke & Devrient GmbH
Board: 3.4.02
Headnote: -
Relevant legal provisions:
European Patent Convention 1973 Art 56
European Patent Convention 1973 R 86(3)
Keywords: Inventive step (no)
Admissability of fifth auxiliary request at the oral proceedings (no)
Catchwords:

-

Cited decisions:
T 0095/83
T 0270/90
Citing decisions:
-

Summary of Facts and Submissions

I. European patent No. 0 502 111 (application No. 91 900 961.3) was revoked by decision of the Opposition Division.

The reason for the revocation was that the subject-matter of claim 1 as granted did not involve an inventive step in the sense of Article 56 EPC in view of the disclosure in documents:

D1: DE-A-2 649 479

D3: EP-B-0 034 392.

The Opposition Division in particular considered that it would be obvious to a person skilled in the art interested in obtaining interference effects from a laminate to include an embossing step as taught in document D1 in the manufacturing method described in document D3, and thus to arrive at the claimed method.

II. The appellant (proprietor of the patent) filed an appeal against the decision revoking the patent.

III. In a communication pursuant to Article 11(2) of the rules of procedure of the Boards of Appeal, issued in preparation for the oral proceedings which were held on 29. April 1998, the Board inter alia drew the parties' attention to the contents of document:

D6: JP-A-62-283 382.

A translation into English of document D6, which was prepared on the Board's behalf, was transmitted to the parties on 2 April 1998.

IV. The appellant requested that the decision under appeal be set aside, and that the patent be maintained, either as granted (main request) or with a single independent claim as filed with his letter of 21 October 1996 (first auxiliary request).

Appellant's second to fifth auxiliary requests were directed to the maintenance of the patent on the basis of a series of further single independent claims filed during the oral proceedings on 29 April 1998.

Claim 1, the only independent claim of appellant's main request, reads as follows:

"1. Method for producing a material embodying an interference pattern, for example a holographic image, comprising the steps of:

- providing a base film,

- solvent coating a transparent, thermoformable lacquer on one side of the base film which lacquer is capable of forming a releasable, direct bond with the base film,

- drying the lacquer so as to form a solid lacquer layer,

- introducing an interference pattern by embossing the side of the solid lacquer layer which faces away from the base film with a printing device carrying the negative of said interference pattern,

- cladding the embossed side of the lacquer layer with a metal layer,

- glueing a substrate onto the metal layer, and

- releasing the base film from the lacquer layer."

Claim 1 of appellant's first auxiliary request is distinguished from claim 1 of the main request in that the paragraph which defines the solvent coating step is supplemented at its end with the expression "and which lacquer is plasticized with a plasticizer,".

Claim 1 of appellant's second auxiliary request reads as follows:

"1. Method for producing a sheet material, such as packaging paper, comprising the steps of:

- providing a base film,

- solvent coating a transparent, thermoformable lacquer, on one side of said base film, which lacquer is capable of forming a releasable, direct bond with the base film, and which lacquer is plasticized with a plasticizer,

- drying the lacquer so as to form a solid lacquer layer,

- introducing an interference pattern by embossing the side of the plasticized, solid lacquer layer which faces away from the base film with a printing device carrying the negative of said interference pattern,

- cladding the embossed side of the lacquer layer with a metal layer,

- glueing a sheet-type substrate onto the metal layer,

- stripping off the base film by means of a roller so as to obtain the sheet material comprising the sheet-type substrate, glue, metal layer and embossed lacquer layer."

Claim 1 of appellant's third auxiliary request is distinguished from Claim 1 of his second auxiliary request in that the expression "having a contact angle of zero degrees with respect to the base film" has been inserted into the paragraph defining the solvent coating step, to replace the comma after "thermoformable lacquer".

Claim 1 of appellant's fourth auxiliary request reads as follows:

"1. Method for producing a packaging paper, comprising the steps of:

- providing a base film,

- solvent coating a transparent, thermoformable lacquer, on one side of said base film, which lacquer is capable of forming a releasable, direct bond with the base film, which lacquer is plasticized with a plasticizer,

- drying the lacquer so as to form a solid lacquer layer,

- introducing an interference pattern by embossing the side of the plasticized, solid lacquer layer which faces away from the base film with a printing device carrying the negative of said interference pattern,

- said step of embossing the lacquer layer being carried out at relatively low pressure and temperature,

- cladding the lacquer layer with a metal layer,

- glueing a sheet-type substrate onto the metal layer,

- stripping off the base film by means of a roller so as to obtain the packaging paper comprising the sheet-type substrate, glue, metal layer and lacquer layer."

Claim 1 of appellant's fifth auxiliary request is distinguished from Claim 1 of his fourth auxiliary request in that the expression "from the group comprising phtalates, citrates, phosphates, adipates, azelates, sebacates, ditridecyl phtalates and polymeric plasticizers of polyethers and polyurethanes" has been added at the end of the paragraph defining the solvent coating step, after "a plasticizer".

V. The respondent (opponent) requested that the appeal be dismissed (main request). As an auxiliary request, in case the Board envisaged to decide to maintain the patent as amended in accordance to the appellant's fifth auxiliary request, the respondent requested that the oral proceedings be adjourned and that costs incurred be awarded to him.

VI. Appellant's arguments in support of his requests can be summarized as follows.

The invention of the patent in suit relates to the manufacturing of packaging paper, which is quite different from the manufacturing of transfer foils to be applied by hot stamping onto various objects, as disclosed in document D1 and most of the cited prior art documents. The manufacturing of transfer foils is subjected to a number of technical constraints, which would render it totally unsuitable for the manufacturing of packaging paper.

In particular, hot stamping of transfer foils involves high pressure and temperatures being applied to limited portions of the foils through a dye, resulting in a breaking of the foils along the outline of the dye. Since the interference pattern previously embossed into the lacquer layer should not be altered in the hot stamping step, it is necessarily formed under high pressure and high temperature conditions, into a hard layer material.

In contrast, the invention is based on the manufacturing process of document D3, in which packaging paper is obtained by providing a soft and flexible lacquer layer onto a base film, the whole surface of which can easily be stripped off by means of a roller without any risk of breakage of the film.

Since document D1, like all the prior art citations relating to the manufacturing of hot stamping transfer foils, discloses an embossing operation which is performed at high pressure and high temperature conditions, it cannot suggest the low pressures and temperatures used in the embossing step of the present invention, nor the addition of a plasticizer into the composition of the lacquer layer which receives the embossed interference pattern.

It has also been recognized that in the method of the invention, a small proportion of the solvent used for coating the lacquer onto the base film remains within the lacquer layer, of which it improves the deformability and flexibility in combination with a definite amount of plasticizer.

In addition, an intermediate wax layer is formed between the base film and the thermoformable lacquer in the method of document D1, in such a way as to cause separation of the base film upon heating during the hot stamping process. The absence of such intermediate release layer is however an essential aspect of the present invention, which is not disclosed either in document D6.

In his written submissions the appellant also stressed that document D3, published in August 1981, referred to document US-A-3 235 395, which was published as early as February 1966 and which already related to a method wherein a base film was coated with a lacquer layer, without interposition of a wax layer. Document D1 was published in May 1978, thus, it was more than eleven years counted from the publication date of document D1 and more than twenty-three years counted from the publication of US-A-3 235 395, before the claimed manufacturing process was envisaged. Taking into account that the process according to the invention fulfilled a long-felt need to manufacture luxury packaging material at higher speed and at lower costs, the above long delay was certainly an indication for an inventive step.

With respect to the question of the admissibility of his fourth and fifth auxiliary requests, presented only at the end of the oral proceedings of 29 April 1998, the appellant indicated that in his experience, it was common practice of the instances of the EPO to accept such requests. Furthermore, the additional features introduced into claim 1 of the fourth auxiliary request to specify that the sheet material produced by the claimed method was a packaging paper and that the step of embossing the lacquer layer was carried out at relatively low pressure and temperature were already implicitly included in the claims of the preceeding requests, and had been amply discussed, accordingly. Claim 1 of the fifth auxiliary request had been supplemented with a list of specific plasticizers in order to better stress the inventive presence of such plasticizers. The appellant however indicated that he did not claim to have invented these specific plasticizers.

VII. The respondent for his part approved of the Opposition Division's reasoning as to lack of inventive step and submitted the following additional arguments.

Document D1, and the other citations relating to the manufacturing of hot stamping transfer foils cannot be considered to pertain to a different technical art than the claimed invention. These documents are indeed directed to the manufacturing, among others, of credit cards provided with a hologram, which is also an application explicitly envisaged in the patent in suit, and a hot stamping transfer foil certainly constitutes a sheet material comparable to packaging paper.

As compared to the method disclosed in documents D1 or GB-A-2 129 739 (D4), the claimed method only uses a different lacquer material, which does not require any intermediate wax release layer. Such lacquer material is however known from document D3, and also document D6 shows a manufacturing method in which a thermoformable lacquer layer for receiving an embossed interference pattern is directly solvent coated onto a base film.

Introducing plasticizers into plastic materials to improve their workability is a most common measure, as is evidenced for instance by the document:

Kunststoff-Lexikon, Carl Hanser Verlag, Munich and Vienna, 7th edition, 1981, pages 361, 555 and 556 (D5).

Neither can the proper selection of adequate pressure and temperature conditions for an embossing operation be considered to go beyond the skilled person's normal capabilities.

Concerning the question of the admissibility of appellant's late fourth and fifth auxiliary requests, the respondent accepted that claim 1 of the fourth auxiliary request did not raise fundamentally new issues which had not been considered earlier in the procedure. However, assessment of the merits of the specific plasticizers identified for the first time in claim 1 of the fifth auxiliary request called for advice from a competent specialist of such plasticizers. The surprising move of the appellant could not have been anticipated by the respondent, who could hardly have prepared an adequate reaction.

Reasons for the Decision

1. The appeal is admissible.

2. Appellant's main request

2.1. Novelty of the subject-matter of claim 1 of appellant's main request was not contested by the respondent.

In particular, document D3 discloses a method for producing a laminate material, which comprises a sequence of manufacturing steps from which the sequence defined in claim 1 is distinguished by the additional step of embossing the solid lacquer with a printing device carrying the negative of an interference pattern (see D3, claim 2).

Document D1 for its part discloses a method for producing a material embodying an interference pattern, for example a holographic image which comprises most of the steps set out in present claim 1, but in which an intermediate release layer 2 is provided between base film 1 and lacquer layer 3 (see Figure 1 and description page 6, last paragraph to page 7, first paragraph). The method set out in present claim 1 is distinguished from this known method in that the lacquer layer is provided directly onto the base film and is capable of forming a releasable, direct bond with it.

2.2. Present claim 1 is not expressly limited to the manufacturing of large sheets of material comprising interference patterns extending over a large portion of their surface, such as luxury packaging paper, as was submitted by the appellant. It could, at least formally, be considered to encompass methods of providing any kind of support with an interference pattern or holographic image.

However, taking into account the specific embodiments disclosed in the patent, which all relate to the manufacturing of packaging paper, the references made in the description to the content of document D3, which is also dedicated to the manufacturing of packaging paper, and the identity of certain figures of the drawings of the patent in suit with those of document D3, the choice of the method disclosed in the latter document as constituting the nearest prior art, which was made also by the Opposition Division and not contested by the parties, seems technically reasonable.

2.3. In the manufacturing method disclosed in document D3, the smooth surface of a lacquer layer formed upon a base film is clad directly, without any intermediate embossing operation, with a metal layer, so as to obtain as an end product a metallised packaging paper having a regularly reflecting mirror surface (see column 2, lines 14 to 17 and column 3, lines 33 to 39).

The distinguishing feature of the method set out in claim 1, which consists in introducing an interference pattern by embossing the side of the solid lacquer layer which faces away from the base film with a printing device carrying the negative of said interference pattern, results in a three-dimensionally structured reflective metallic surface instead of the smooth surface of document D3. Such structured surface is able of generating optical interference effects, which confer a particularly attractive visual aspect to the material so produced, rendering it highly suitable for being used as luxury packaging paper (see column 3, lines 22 to 24 of the present description).

Thus, the technical problem solved by the claimed method can be seen, generally, in providing a method for manufacturing a packaging paper of an improved visual attractivity, as compared to the packaging paper produced in accordance with the method of document D3.

The mere formulation of the above technical problem cannot, in the Board's view, provide any positive contribution for the assessment of the inventive step involved by the claimed method, and this was not alleged by the appellant either. As a matter of fact, optical aspect and visual attractivity are common concerns in the manufacturing of the packaging paper, which are illustrated for instance by the suggestions made in document D3 to dye or pigment the lacquer layer (see column 2, lines 49 to 52) or to deposit the metal layer in spaced or interconnected bands, strips, or lines for decorative or ornamental purposes (see column 3, lines 8 to 13 and column 4, line 62 to column 5, line 4).

2.4. The skilled person starting from the method of document D3 and striving at solving the above technical problem would in the Board's view look for prior art techniques expressly dedicated to the producing of optical, decorative effects in a transparent lacquer layer cladded with a metal layer, similar to the lacquer layer at the surface of the packaging paper of document D3.

The introductory portion of document D1 explicitly states that particularly interesting optical effects can be obtained, when a metal layer of substantial constant thickness is deposited onto the surface of a lacquer layer which is provided with the structured pattern (see page 3, last paragraph), whereby the structured pattern is embossed with a printing device 30. carrying the negative of said pattern (see Figure 3). Document D1 admittedly does not specify that the structure pattern forms an "interference" pattern in the sense of claim 1, stating only that the pattern gives rise to different light reflection or light refraction (see page 3, lines 5 to 14). A very similar technique is disclosed in document D6, in particular for the illustration of books, in which, like in the patent in suit, holograms are employed "on account of their ornamental character in emitting light with rainbow colours and their surprise effect due to the three-dimensional appearance". These holograms are embossed into the surface of a solid resin layer with a printing device carrying the negative of an interference pattern, the embossed layer being then clad with a metal layer and transferred to a paper surface (see the translation into English of document D6, page 2, lines 21 to 35 and page 6, the first paragraph below the table).

Document D4 also discloses the embossing of a hologram into the surface of a transparent thermoplastic layer clad with a metal layer, and its transferring onto any document "where a particularly unusual and attractive effect is desired" (see page 1, lines 110 to 115).

Thus, in the Board's opinion, the skilled person would easily derive from the prior art the idea of increasing the visual attractivity of the packaging paper obtained by the method of document D3 by providing it with an interference pattern or holographic image of the kind disclosed in documents D1, D4 or D6. Documents D1, D4 and D6 consistently teach that a three-dimensional or holographic pattern can be introduced by embossing the solid thermoformable layer which faces away from a base film with a printing device carrying the negative of said pattern, said embossing operation being performed in accordance with documents D1 and D6 before the surface of a solvent coated, transparent thermoformable layer is clad with a metal layer. The laminate produced by the method of document D3, which is the starting point for the skilled person's considerations, also comprises a transparent, thermoformable layer which is solvent coated onto a based film before being clad with a metal layer. Accordingly, it would seem obvious for the skilled person to introduce the desired pattern by embossing the side of the thermoformable layer which faces away from the base film with a printing device, before cladding the embossed surface with a metal layer, like in documents D1 or D6.

The appellant in this respect submitted that the skilled person would not seriously consider the teaching of documents D1, D4 or D6, because these documents related to the application of transfer foils onto substrates by a hot stamping procedure, which implied the use of transparent, thermoformable layers exhibiting a greater hardness and being capable of resisting higher temperature and pressure conditions than the lacquer layer used in document D3 for the production of packaging paper. He also stressed that the prior art did not disclose the embossing of a solid lacquer layer directly formed upon the surface of a base film, i.e. without any intermediate wax layer.

However, the Board is not convinced that the solid lacquer layers or the transfer foils disclosed in documents D1, D4 or D6 exhibit mechanical properties so fundamentally different from those of the lacquer layer of document D3, that the skilled person would have been deterred from at least trying to perform the embossing operation also onto the lacquer layer of document D3. On the contrary, the reference made in the description of the present patent to the advantages brought by the optional addition of plasticizer into the lacquer layer in reducing temperature and pressure requirements for the embossing operation (see column 3, lines 3 to 11) suggests that the unplasticized lacquer layer is relatively hard. In addition, the lacquer layers of documents D1 and D6 are obtained substantially in the same way as the lacquer layer disclosed in document D3 and defined in present claim 1, i.e. by solvent coating a transparent, thermoformable lacquer which is subsequently dried (see document D1, example 2 as described in the passage bridging pages 8 and 9 or the translation into English of document D6, page 3, lines 34 to 41). The last mentioned passage of document D6 also shows that, contrary to appellant's submission, the embossing of a hologram image onto a lacquer layer directly formed onto a base film is explicitly disclosed in the document. Accordingly, the mechanical properties of the lacquer layer used in the transfer foils of documents D1 and D6 would not be expected to be fundamentally different from those of the lacquer layer in the packaging paper of document D3.

The scant description of the embossing step in the present patent does not either appear to support the existence of any particular difficulties caused by the mechanical properties of the solid lacquer layer, which could deter the skilled person from at least trying to perform the embossing operation, and thus to arrive at the claimed method.

In support of his argumentation in favour of the non-obviousness of the claimed method, the appellant also referred to the long span of time between the date of publication of the citations invoked by the respondent, of which the last, document D3, was published in 1981, and the priority of the present patent, which is in 1989. He did not however demonstrate nor produce any evidence that a noticeable amount of efforts had been made in the interval to solve the technical problem underlying the invention, nor that there was any long-felt need of manufacturing a packaging paper having an improved visual appearance.

For these reasons, the subject-matter of claim 1 of appellant's main request does not in the Board's opinion involve an inventive step in the sense of Article 56 EPC.

3. Appellant's first auxiliary request

Claim 1 of appellant's first auxiliary request is distinguished from claim 1 of his main request by the additional feature that the transparent, thermoformable lacquer is plasticized with a plasticizer.

The addition of plasticizers is a well known means of reducing the solidification temperature, brittleness and hardness of synthetic materials, and to improve their workability, as is evidenced by document D5, and was not contested by the appellant. In the Board's opinion, once the skilled person has envisaged to emboss the solid lacquer layer of document D3 with a printing device to introduce into it an interference pattern, which is obvious for the reasons given above in relation with appellant's main request, he would without the exercise of inventive ingenuity select adequate operation conditions for the embossing step. The workability or consistence of the material of the lacquer layer is an evident parameter upon which the skilled person can exert an influence, in particular through the addition of an appropriate amount of plasticizers.

Accordingly, the subject-matter of claim 1 of appellant's first auxiliary request is not considered to involve an inventive step in the sense of Article 56 EPC.

4. Appellant's second and third auxiliary requests

Claim 1 of appellant's second auxiliary request corresponds in substance to claim 1 of his first auxiliary request with the additional limitation that the material to be produced by the method is specified to be a "sheet material such as packaging paper", and that the releasing of the base film from the lacquer layer at the last step of the method is specified to be obtained by "stripping off the base film by means of a roller".

Claim 1 of appellant's third auxiliary request is identical to claim 1 of his second auxiliary request, with the additional limitation that the transparent, thermoformable lacquer which is solvent coated onto the base film is specified to have "a contact angle of zero degrees with respect to the base film".

The method of document D3, which as the nearest prior art is the starting point for the assessment of inventive step of the claims of appellant's main and second auxiliary requests, already produces "a sheet material, such as packaging paper" (see column 3, lines 34 to 39), from which the base film is stripped off by means of a roller (see roller D on Figure 5), the lacquer also having a contact angle of zero degrees with respect to the base film (see claim 1).

Accordingly, claims 1 of appellant's second and third auxiliary requests, as compared to claim 1 of his first auxiliary request, have only been supplemented with features already present in the nearest prior art as disclosed in document D3. The subject-matter of these claims does not therefore involve an inventive step in the sense of Article 56 EPC either, for the reasons already given in relation with claim 1 of the first auxiliary request.

5. Appellant's fourth auxiliary request

Claim 1 of appellant's fourth auxiliary request corresponds in substance to claim 1 of his second auxiliary request with the additional limitations that the "sheet material, such as packaging paper" is now definitely specified to be "packaging paper" and that the step of embossing the lacquer layer is specified to be "carried out at relatively low pressure and temperature".

The limitation of the claim to the producing of a packaging paper does not change the situation with respect to the assessment of inventive step, because the method of documents D3, which is the nearest prior art, is also specifically dedicated to the manufacturing of such packaging paper.

The pressure and temperature conditions of the embossing step constitute, besides the workability of the lacquer material, most obvious operational parameters to be properly selected by the skilled person, when he envisages to emboss the lacquer layer with an interference pattern.

The manufacturing of a packaging paper as disclosed in document D3 does not require any high temperature and pressure treatment like the hot stamping operation disclosed in documents D1, D4 or D6, which calls for still higher temperature and pressure conditions for the embossing step in order to avoid that the embossed pattern be later destroyed during the hot stamping operation. The skilled person would not therefore, in the Board's opinion, have any reasonable ground not to select for the embossing of the lacquer layer in the manufacturing of a packaging paper "relatively low pressure and temperature" conditions in the sense of claim 1 of appellant's fourth auxiliary request, i.e. pressure and temperature conditions below those of the known hot stamping procedure.

For these reasons, the subject-matter of claim 1 of appellant's fourth auxiliary request is not considered to involve an inventive step in the sense of Article 56 EPC.

6. Appellant's fifth auxiliary request

Claim 1 of appellant's fifth auxiliary request is identical to claim 1 of his fourth auxiliary request, with the additional limitation that the plasticizer in the transparent, thermoformable lacquer is specified to be selected from the group comprising phtalates, citrates, phosphates, adipates, azelates, sebacates, ditridecyl phtalates and polymeric plasticizers of polyethers and polyurethanes.

6.1. Admissibility of the request

The appellant filed his fifth auxiliary request only towards the end of the oral proceedings held on 29. April 1998.

The Board cannot agree to his submission that it would be common practice of the Boards of Appeal to accept such late filed requests. As a matter of fact, the established practice of the Boards when deciding upon the admission of late requests into the procedure, is to exert their discretion under Rule 86(3) EPC with caution, taking in particular in due consideration whether there was some clear justification both for the amendments proposed and for the late submission (see decision T 95/83, OJ EPO 1985, 75) or whether, for reasons of fairness to the other party, they were simple and clear enough to be understood immediately and were obviously allowable (see decision T 270/90, OJ EPO 1993, 725).

In the present procedure, the admissibility of appellant's second to fourth auxiliary requests, all filed during the oral proceedings, was recognized because, on the one hand, the wording of claim 1 of the second and third auxiliary requests only differed from the wording of the corresponding claims filed by the appellant one month before the oral proceedings in that they were re-drafted in the one-part form, after the Board had objected to certain unclarities caused by the proposed two-part form. On the other hand, claim 1 of the fourth auxiliary request had only been supplemented with features specifying that the material produced was packaging paper and that the embossing was performed at relatively low pressure and temperature, which had already been amply discussed in the proceedings in relation to the earlier requests. The respondent himself explicitly indicated that he had no objection to the fourth auxiliary request being considered by the Board.

In contrast, the introduction into claim 1 of the fifth auxiliary request of the list of specific compounds from which the plasticizer of the transparent, thermoformable lacquer should be selected, surprisingly introduces new issues. The fact that this list of compounds could be of any relevance to the procedure could hardly have been forseen by the respondent or the Board, the less so since the list had not been specified in any of the dependent claims as originally filed or as granted.

In addition, the appellant himself admitted that he did not claim any inventive merit of the compounds identified in the list, which were all well known plasticizers. The Board cannot therefore see any justification for the appellant filing at this late stage amendments which, a priori, cannot reasonably be expected to substantially modify the issue on inventive step, and thus to result in an allowable claim.

For these reasons appellant's fifth auxiliary request is not considered to be admissible.

The respondent's auxiliary requests for postponement of the oral proceedings and apportionment of costs, which were subject to the condition of the Board envisaging to allow appellant's fifth auxiliary request, need not be considered, accordingly.

ORDER

For these reasons it is decided that:

The appeal is dismissed.

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