T 2148/21 (Laminated glass/Sekisui Chemical) 06-07-2023

Main request

1. Inventive step

1.1 The patent in suit relates to a laminated glass with an interlayer film, used for automobiles, buildings etc., having high heat shielding properties and high visible light transmittance (paragraphs [0001] and [0009]).

1.2 D4 relates to a similar purpose (paragraphs [0001] and [0007]) and is a suitable starting point for assessing inventive step. D4 describes a laminated glass in which the interlayer film is composed of a first thermo­plastic resin layer, a heat reflecting film and a second thermoplastic resin layer, the second thermoplastic resin layer having a heat shielding function (Figure 1; claim 2). According to Working Example 1, these are a first polyvinyl butyral (PVB) layer free from ITO fine particles, a heat reflecting film and a second PVB layer with ITO fine particles dispersed therein functioning as a heat absorbing layer. The content of the ITO fine particles is 0.7% by weight (paragraphs [0033] and [0034]). D4 already provides high (initial) heat shielding properties and visible light transmittance (Working Example 1).

1.3 The technical problem may be considered that of better retaining the desired properties, in particular the visible light transmittance, during use ("the visible light transmittance becomes further difficult to be lowered", paragraph [0094] of the patent in suit).

1.4 As the solution to this problem, the claimed laminated glass is proposed, in which the first and second resin layers of the interlayer film both contain a UV shielding agent.

1.5 In light of the experimental report D18, it may be accepted that this problem has been solved.

1.6 D9 also relates to a laminated glass comprising an interlayer film containing a heat shielding metal oxide and already addresses the problem of deteriorating visible light transmittance or durability to light (D9, paragraph [0012]). D9 attributes this problem of deterioration to a chemical change of the heat shielding metal oxide by UV rays, which affects the resin matrix (same paragraph). As the solution to this problem, D9 proposes a UV shielding layer (paragraphs [0009] and [0014]). While D9 separately refers to a "heat shielding layer" and a "UV shielding layer" (see e.g. claim 1 of D9), it is clear from the experimental protocol used (Example 1, paragraphs [0103]-[0107]) that the UV shielding agent is present in both these layers in the exemplified embodiments. Specifically, a plasticizer solution containing a UV absorbent is prepared and the ITO powder is loaded into the obtained plasticizer solution, which is then added to PVB resin to obtain a heat shielding layer (paragraphs [0103]-[0106]; heat shielding layer A). This ITO-containing heat shielding layer consequently contains a UV absorbent. A UV shielding layer containing no ITO is also produced by using the same initial UV absorbent-containing plasticizer solution and adding it to PVB resin (paragraph [0107]).

There is no reason why the skilled person would not rely on this example in D9. The observation that the general description in D9 (paragraphs [0016]-[0054]) does not explicitly mention the additional presence of UV shielding agent in the heat shielding layer would not lead the skilled person to disregard Example 1 of D9, or to disregard the presence of UV shielding agent in the heat shielding layer as an accidental, non-functional aspect of it. It is not convincing either that the skilled person would refrain from a UV shielding agent merely to save costs; it may even be more efficient if the same UV absorbent-containing solution is used in both resin layers, as in Example 1 of D9.

Since it is the ITO-containing layer which is prone to degradation by UV rays (D9, paragraphs [0012] and [0013]), the skilled person would expect that the presence of the UV shielding agent in the heat shielding layer may contribute to the desired function of preventing this degradation.

1.7 Example 1 of D9 illustrates the general experimental protocol which is also used in the other examples, in particular for preparing heat shielding layer B (Example 2). The examples do not contradict the general description of D9. It can be seen that they solve the stated problem (Tables 1 and 3 and paragraphs [0148] and [0149]).

The skilled person would thus derive that the presence of the UV shielding agent in both the heat shielding layer and the UV shielding layer is a particular embodiment of the teaching of D9, and they would rely on this embodiment because the successful solution of the technical problem has been demonstrated for it.

1.8 In summary, the skilled person starting from D4 would be faced with the problem of deteriorating visible light transmittance and would find the solution to this problem in D9, namely the presence of a UV shielding layer and a heat shielding layer with UV absorbent present in both these layers.

1.9 The skilled person would readily apply the solution taught in the examples of D9 to D4, in particular as both documents relate to a structurally similar film of laminated layers comprising an ITO-containing PVB layer. By contrast with the appellant's view, it cannot be said that the teaching of D4 and D9 would be conceptually so different from one another that the skilled person would not have combined them.

The teaching of D9 is not limited to films consisting of a UV shielding layer and a heat shielding layer; see also paragraphs [0099] and [0100]. Moreover, the UV shielding layer is not required to be directly adjacent to the heat shielding layer, nor can any such requirement be derived from the intended functions of the layers. The additional presence of a heat reflecting film in Example 1 of D4 would therefore not have prevented the skilled person from applying the teaching of D9 to the structure exemplified in D4.

1.10 By contrast with the appellant's view, applying the teaching of D9 to D4 would not entail additional modifications such as providing additional layers. Nor would it involve adding or inserting the two-layer laminate of Example 1 of D9 as an additional layer in the structure known from D4. On the contrary, the skilled person would immediately understand that the teaching of D9 regarding the presence of an ITO-containing heat shielding layer and a UV shielding layer, both containing a UV absorbent agent, may be accomplished in the structure known from D4 by adding a UV absorbent to the relevant layers, i.e. to both the ordinary and the ITO-containing PVB layer, which according to D4 are arranged on opposite sides of the heat reflection layer. There is thus no need to add further layers to the structure known from D4, the result being a laminated glass with an interlayer film within the scope of claim 1 at issue.

1.11 The appellant's argument that the skilled person wishing to implement the teaching of D9 would have taken a stepwise approach and in a first step would have added the UV absorbent only to the heat shielding layer is not convincing either. This first step would in fact reflect the comparative examples of D9 in which there is only the heat shielding layer containing a UV absorbent (heat shielding layer A or B, see Table 3) but no additional UV shielding layer. This would be contrary to the teaching of D9, which requires the presence of an additional UV shielding layer (i.e. a UV shielding layer in addition to the heat shielding layer) as an essential feature (claim 1 of D9). Whether adding the UV absorbent to only the heat shielding layer would have a disadvantageous effect, as argued by the appellant, is thus irrelevant because, as indicated, the skilled person would not have taken the stepwise approach in the first place.

1.12 The subject-matter of claim 1 consequently lacks an inventive step, in line with the impugned decision.

Auxiliary request 1

2. Inventive step

2.1 Reference is made to the comments regarding the main request (see point 1.). In auxiliary request 1, it is additionally specified that the second resin layer contains at least one kind from among a phthalocyanine compound, a naphthalocyanine compound and an anthracyanine compound ("Ingredient X"). The presence of Ingredient X constitutes a further difference over D4.

2.2 According to the patent in suit, this ingredient functions as a heat shielding compound (paragraph [0075]).

2.3 The appellant argued that the effect of Ingredient X was not limited to additional heat shielding but was functionally interdependent with the UV shielding agent, giving rise to a combined effect. Impinging UV rays would provoke the degradation of Ingredient X and would considerably impair long-term visible light transmittance. This was prevented by the presence of the UV shielding agent.

2.4 However, the available examples in the patent in suit and in test reports D19 and D21, in so far as they relate to Ingredient X, only show the initial properties. It can be seen that increasing amounts of X result in better heat shielding but lower visible light transmittance (D19, Table 5, Tests 1-3; D21, Table 5, Tests 4-7). While these examples do not illustrate the stability over time and thus do not prove the combined effect, it may nevertheless be acknowledged that there is a functional interdependence of using Ingredient X and a UV shielding layer because this is confirmed by D14.

2.5 The problem may thus be considered that of providing a laminated glass that has improved heat shielding and good visible light transmittance and better retains these properties over time.

2.6 The skilled person would have been aware of D14, which relates to a laminated glass having high heat shielding properties (paragraph [0001]). D14 already teaches how to improve the heat shielding properties while maintaining the visible light transmittance, and how to maintain these properties over time.

Specifically, D14 addresses the problem of insufficient heat shielding properties of laminated glass comprising ITO particles in the interlayer film (paragraph [0008]). D14 teaches that the additional presence of Ingredient X (in conjunction with the heat shielding particles) increases the heat shielding properties and the visible light transmittance (paragraph [0042]). D14 furthermore describes that the heat shielding properties eventually decrease (paragraph [0044]). According to D14, a UV shielding layer is therefore provided (paragraph [0044]). It is taught that this prevents a chemical change of Ingredient X and a deterioration of the resin which can be caused by this chemical change (same paragraph). The heat shielding layer preferably also contains a UV shielding agent (paragraph [0096]), as is additionally shown in e.g. Example 1 of D14. Furthermore, the examples show good retention of the desired properties over time (Table 5).

2.7 The skilled person starting from D4 and faced with the problem posed (see point 2.5) would readily apply this teaching of D14 to D4, with the expectation of obtaining improved heat shielding and durability over time. They would thus provide an Ingredient X and a UV shielding agent in the heat shielding layer. They would also provide a UV shielding agent in the first resin layer, referred to as the "ordinary first interlayer" in D4, such that the first resin layer functions as a UV shielding layer within the meaning of D14, as indicated.

2.8 The board cannot agree with the appellant's view that this would entail laminating the UV shielding layer directly on a surface of the heat shielding layer. While this structure is present in the examples of D14, it is not an essential feature of the teaching of D14. In the examples, each layer (the heat shielding layer and the UV shielding layer) is separately produced. It cannot be concluded that they necessarily have to be arranged in the exemplified directly laminated structure. The skilled person applying the teaching of D14 to D4 has no reason to additionally modify the arrangement of the layers in D4, in which the first resin layer and the heat shielding layer are adhered to opposite surfaces of the heat reflecting film.

2.9 In the general part of D14 it is expressly foreseen that a different layer from the heat shielding layer and the UV shielding layer may be sandwiched between them (paragraph [0052]). The heat reflecting film in D4 may be regarded as such a sandwiched layer. Its presence is consequently compatible with D14.

2.10 By contrast with the appellant's arguments, the film's function as specifically a heat reflecting film would not have prevented the skilled person from applying the teaching of D14 to it either.

D14 teaches that heat reflecting laminated glass that has a metal thin film or contains heat reflecting PET reflects not only infrared rays but also communication waves and is therefore not desired in a windshield (paragraph [0011]). However, these disadvantages of the indicated heat reflecting films are unrelated to the problem under consideration here, which concerns the heat shielding properties and the visible light transmittance. Moreover, they relate to different heat reflecting films from that preferred in D4, namely one that does not include metal and is specifically a film formed by layering polyethylene naphthalate and poly(methyl methacrylate) (paragraph [0029] of D4).

2.11 The skilled person starting from D4 would therefore have arrived at the subject-matter of claim 1 by following the guidance of D14 alone, which suggests both distinguishing features.

2.12 The subject-matter of claim 1 consequently lacks an inventive step.

Auxiliary request 2

3. Article 123(2) EPC

3.1 Compared with auxiliary request 1, claim 1 includes the additional feature that the second resin layer contains an oxidation inhibitor.

3.2 In the application as originally filed (paragraph [0109] of the translation, corresponding to paragraph [0108] of the A-publication), the presence of an oxidation inhibitor in the second resin layer is disclosed as one of three alternatives, the other alternatives relating to the presence of an oxidation inhibitor in the first resin layer and to the presence of an oxidation inhibitor in the first and second resin layers. Each of these alternatives is (equally) preferred, there being no preference for the presence of an oxidation inhibitor in the second resin layer.

The examples cannot provide a pointer to the presence of an oxidation inhibitor in specifically the second resin layer either, because the oxidation inhibitor is additionally present in the first resin layer.

The claimed subject-matter involves multiple selections within the general disclosure of the application as originally filed, of not only the oxidation inhibitor specifically in the second resin layer, but additionally of at least the heat shielding particles in addition to Ingredient X (paragraphs [0075] and [0081] of the translation). The combination of features in claim 1 is therefore not directly and unambiguously derivable from the application as originally filed.

3.3 In conclusion, the requirements of Article 123(2) EPC are not met.

Auxiliary request 3

4. Article 84 EPC

4.1 Compared with the main request, claim 1 specifies that "the first resin layer and the second resin layer are each directly layered on the infrared ray reflection layer". This amendment is based on the description. Pursuant to G 3/14 (catchword), it may be examined whether that amendment introduces a lack of clarity.

4.2 The infrared ray reflection layer may itself comprise multiple layers (claim 6). However, no clear criterion is available to determine whether a layer is part of a multilayer IR reflection layer, or an additional intermediate layer. In a case such as this, it is unknown whether the first (or second) resin layer is directly layered on a multilayer IR reflection layer or on an intermediate layer. The appellant's argument that a layer of a multilayer IR reflection layer could be distinguished from other layers because it was very thin is not convincing. There is no evidence that it is necessarily thinner than all the other layers that may possibly be included in interlayer films, irrespective of their function. Nor is there any evidence for the appellant's assertion that the reference to the infrared ray reflection layer, which is a functional definition, specified a distinct set of possible layer materials so that it could be clearly identified and delimited within an interlayer film.

4.3 The amendment consequently results in a lack of clarity.

Auxiliary request 4

5. Inventive step

5.1 Reference is made to the comments regarding the main request which apply accordingly.

5.2 The presence of an oxidation inhibitor in the first and second resin layers constitutes an additional difference over D4.

5.3 An oxidation inhibitor (BHT) is present in all the resin layers exemplified in the patent in suit and in experimental reports D18-D21. There is no comparative example where an oxidation inhibitor is not present. The examples as a whole thus do not specifically address the technical effect of the additional presence of an oxidation inhibitor. Nevertheless, on the basis of the inhibitor's intrinsic function to prevent oxidation, and in line with paragraph [0115], it may be assumed that it contributes to solving the problem posed (see point 1.3) and improves the durability.

5.4 However, adding an oxidation inhibitor is common general knowledge (D1, page 617, "Stabilization Mechanisms") and is already taught in the secondary document D9 (paragraphs [0052]-[0054] and the examples); in fact, the same oxidation inhibitor is used as in the examples of the patent in suit (BHT). The skilled person applying the teaching of D9 to D4 would thus readily include an oxidation inhibitor, with the expectation of obtaining some durability benefit in the light of its intrinsic function.

5.5 This additional feature therefore does not support an inventive step.

Auxiliary request 5

6. Claim 1 of auxiliary request 5 has effectively the same scope as claim 1 of auxiliary request 4. The appellant did not contest that the considerations were the same as for auxiliary request 4.

The subject-matter of claim 1 thus lacks an inventive step for the same reasons (see point 5.).

Auxiliary request 6

7. Inventive step

7.1 Reference is made to the comments regarding the main request (point 1.). Compared with the main request, claim 1 specifies that both the first resin layer and the second resin layer contain a plasticizer, and that the plasticizer includes at least one kind from among triethylene glycol di-2-ethylhexanoate and triethylene glycol di-2-ethylbutyrate (paragraph [0073]). However, the resin layers in D4 contain triethylene glycol di-2-ethylbutyrate (see Working Example 1). The plasticizer is a component of the vinyl-based resin composition. The skilled person would therefore understand that the "ordinary first interlayer", i.e. the PVB interlayer that is free from ITO fine particles, also contains the plasticizer.

7.2 The feature relating to the plasticizer thus does not provide any additional delimitation from D4, and an inventive step is lacking for the same reasons as set out for the main request.

Auxiliary requests 7 and 8

8. Article 84 EPC

8.1 As in auxiliary request 3, claim 1 in auxiliary requests 7 and 8 also specifies that "the first resin layer and the second resin layer are each directly layered on the infrared ray reflection layer". The requirements of Article 84 EPC are consequently not met for the same reasons as indicated for auxiliary request 3 (see point 4.).

Auxiliary request 9

9. Inventive step

9.1 Reference is made to the comments regarding the main request (point 1.). Compared with the main request, claim 1 specifies that the heat shielding particles contain at least one kind from among antimony-doped tin oxide particles, gallium-doped zinc oxide particles, indium-doped zinc oxide particles, tin-doped indium oxide particles and tungsten oxide particles. However, using ITO (tin-doped indium oxide) is already disclosed in documents D4 (Working Example 1) and D9 (Example 1) and thus does not provide any additional delimitation from this prior art.

9.2 An inventive step is therefore lacking for the same reasons as set out for the main request.

Auxiliary requests 10 and 11

10. Article 123(2) EPC

10.1 Compared with claim 1 as granted, it is additionally specified that the second resin layer contains at least one kind from among a phthalocyanine compound, a naphthalocyanine compound and an anthracyanine compound (as in auxiliary request 1; based on claim 9 as granted). Furthermore, claim 1 was amended to stipulate an upper limit of the content of Ingredient X in 100% by weight of the second resin layer ("0.1% by weight or less" in auxiliary request 10, "0.05% by weight or less" in auxiliary request 11).

10.2 According to the appellant, this amendment was based on paragraphs [0074] and [0079] (referring to the A-publication, corresponding to paragraphs [0075] and [0080] as originally filed). It was supported by the examples.

10.3 Paragraph [0080] as originally filed relates to preferred lower and upper limits, according to various levels of preference, of the content of Ingredient X "in the case where the first resin layer or the second resin layer contains the Ingredient X". It is also stated that "[w]hen the content of the Ingredient X in the first and second resin layers is not less than the above lower limit and not more than the above upper limit, the heat shielding properties are sufficiently enhanced and the visible light transmittance is sufficiently enhanced".

10.4 Amended claim 1, by contrast, specifies only the upper limit in the second resin layer but not any lower limit. It is also silent as to the additional presence and content of Ingredient X in the first resin layer, thus allowing for the presence of an undefined content of Ingredient X in the first resin layer. The functional requirement regarding the IR ray transmittance of the relevant "whole layers" does not imply any clear restriction in this regard.

10.5 The examples do not constitute a suitable pointer towards extracting only the disclosure regarding the upper limit of the content of Ingredient X and applying it to the second resin layer only. Where the examples contain Ingredient X, it is present in the second resin layer but absent in the first resin layer, and its content in the second resin layer is not only below the specified upper limit but also above the specified lower limit.

10.6 The subject-matter of claim 1 thus extends beyond the content of the application as originally filed.

Auxiliary request 12

11. Article 84 EPC

11.1 As in auxiliary request 3, claim 1 in auxiliary request 12 also specifies that "the first resin layer and the second resin layer are each directly layered on the infrared ray reflection layer". The requirements of Article 84 EPC are consequently not met for the same reasons as indicated for auxiliary request 3 (see point 4.).

Auxiliary requests 13-16

12. Article 12 RPBA 2020

12.1 Auxiliary requests 13-16 were filed for the first time with the statement of grounds of appeal. They constitute further attempts to address the opposition division's finding of lack of inventive step. However, the issue of lack of inventive step as dealt with by the opposition division had already been raised in the notice of opposition. This included an objection based on the combination of D4 with D9 (point 6.1.6 on page 15 of the notice of opposition). The question whether the teaching of D9 was applicable to other laminates did not newly arise during the oral proceedings before the opposition division.

The point in time when the filing of auxiliary requests 13-16 "appeared attractive for the proprietor for the first time" on the basis of commercial considerations is irrelevant.

12.2 The filing of further auxiliary requests thus cannot be regarded as a response to a procedural development in the opposition proceedings.

Auxiliary requests 13-16 should therefore have been filed before the opposition division. They are not taken into consideration (Article 12(6) RPBA 2020).