T 0609/05 09-08-2007

Reasons for the Decision

1. The appeal complies with Articles 106 and 108 EPC and Rule 64 EPC and is therefore admissible.

2. Priority

2.1 D1, a published European application validly designates all states designated in the patent in suit, and validly claims a priority date of 19 November 1992 from JP 310617/92 (D16). It was published on 25 May 1994. In the decision under appeal D1 was considered to be state of the art pursuant to Article 54(3) and (4) EPC because, according to the opposition division, the claims in suit were not entitled to a priority date of 17 June 1992 from JP 157937/92 but only to a priority date of 26 March 1993 from JP 68282/93. Consequently, a disclaimer was added to Claim 1 to remove Comparative Example 5 of D1 from the scope of the claims (point III (a), above).

2.2 It has never been questioned that the claims of the patent in suit are entitled to a priority date of 26 March 2003 from JP 68282/93. However the respondent argued that partial priority could also be claimed from JP 157937/92 (17 June 1992) which contained a disclosure of all the features of Claim 1 with the exception of parameter (ii) of [B-1]. This parameter was concerned with the relationship between the molecular weight distribution (Mw/Mn) and the melt flow rate (MFR) and stated that:

Mw/Mn >= 7.5 x log(MFR) - 1.2.

Since, however, Mw/Mn of any (co)polymer always was equal to or greater than 1, this parameter (ii) was not a distinguishing feature for a polyethylene [B-1] with an MFR of below 1.97 g/10 min (only an MFR >= 1.97 g/10 min gave a value >= 1 on the right hand side of the above cited relationship). Thus, compositions of the claims in suit which used a polyethylene [B-1] with an MFR below 1.97 g/10 min were identical to those disclosed in JP 157937/92 and therefore entitled to claim a priority date of 17 June 1992. This date was before the valid priority date of D1 and thus Comparative Example 5 of D1, which used a polyethylene with an MFR of 0.50 g/10 min, was not citable against the claims in suit. In that case, the respondent should be allowed to delete the disclaimer in accordance with the exception to the prohibition of reformation in peius as set out in G 1/99 (supra).

2.3 However, the board cannot decide differently on the priority issue from the opposition division for the following reasons:

The parameter (ii) for [B-1] reflects the recognition that the molecular weight distribution depends upon the MFR. It is conspicuous to the board that such a recognition is completely absent from JP 157937/92 which in itself is an indication that JP 157937/92 is not directed to the same invention as the claims in suit. Furthermore, even if one accepts that parameter (ii) in the claims in suit defines two distinct alternatives for the polyethylene [B-1], namely the first alternative with an MFR >= 1.97 g/10 min and the second with an MFR < 1.97 g/10 min (where no restrictions with respect to the molecular weight distribution exist), it is conspicuous to the board that JP 157937/92 does not disclose that second alternative. In fact, JP 157937/92 does not disclose an MFR of 1.97 g/10 min or a range below that value, let alone the relevance of such a range in relation to the molecular weight distribution. Therefore, the requirement for claiming priority as set out in G 2/98 (OJ EPO 2001, 413, headnote), namely "that priority of a previous application in respect of a claim in a European patent application in accordance with Article 88 EPC is to be acknowledged only if the skilled person can derive the subject-matter of the claim directly and unambiguously, using common general knowledge, from the previous application as a whole", is not met for the "second" alternative identified by the respondent. Consequently, partial priority cannot be claimed from JP 157937/92 and Comparative Example 5 is citable against the claims in suit under Article 54(3) and (4) EPC.

2.4 In view of the board's finding on the priority issue, the respondent did not pursue its request to delete the disclaimer from Claim 1.

3. Article 100(c) EPC / amendments

3.1 Claims 1-7 of the main request are identical with the claims as allowed by the opposition division (point III (a), above).

3.2 The opposition division's finding that Claim 5 of the main request meets the requirements of Articles 100(c) and 123(2) EPC, respectively, as well as the finding that the amendments to Claim 1 of the main request meet the requirements of Articles 123(2) and (3) and 84 EPC was not challenged by the appellant. Nor does the board see any reason to raise an objection of its own.

3.3 As regards the disclaimer in Claim 1, it is apparent from the priority discussion in point 2, above, that the disclaimer has been introduced to restore novelty by delimiting the claim against state of the art under Article 54(3) and (4) EPC. This is, according to G 1/03 (OJ EPO, 2004, 413, headnote II.1), allowable.

3.4 Thus, no formal objections arise against Claims 1-7 of the main request.

4. Sufficiency of disclosure (main request)

4.1 In Claim 1 of the main request the melt tension (MT) of the ethylene/C3-20 alpha-olefin copolymer [A-1] is set in a relationship with the melt flow rate (MFR) of [A-1] such that MT > 2.2 x MFR-0.84. With respect to the parameter MT, the appellant raised two objections, namely, (i) that it was in principle not possible to measure MT for a copolymer [A-1] having a MFR of less than around 0.1 or in excess of around 10 g/10 min and (ii) that it was not clear how MT had to be measured.

4.2 As regards objection (i), it is conspicuous to the board that the appellant has not provided any evidence in support of this objection whereas the respondent has submitted an Experimental Report 2 (D21) where the MT value was determined for a copolymer [A-1] having an MFR of 26.7 g/10 min. Furthermore, the application as originally filed discloses in Table 10 three copolymers with an MFR of 123, 165 and 19.2 g/10 min, respectively, whereby for all these copolymers a MT value of > 0.1 g is indicated. Although no exact values are given, it is nevertheless evident from Table 10 that the MT values were measured. Finally, D4 discloses in Example 5 a copolymer which has an MFR of 0.075 g/10 min and an MT of 42 g. All these data show that the MT value can be determined for samples with an MFR of less than 0.1 or in excess of 10 g/10 min. Hence, the appellant's allegation that the invention cannot be worked over the whole range claimed is without merit.

4.3 With respect to the measurement of MT, it is apparent from Claim 1 that the parameter is measured at 190ºC. The measurement is explained in further detail at page 4, line 54 to page 5, line 1 of the patent in suit (corresponding passage on page 25, lines 17-27 of the application as originally filed):

"In the invention, the melt tension (MT (g)) of an ethylene/alpha-olefin copolymer is determined by measuring a stress given when a molten copolymer was stretched at a constant rate. That is, a powdery polymer was melted in a conventional manner, and the molten polymer was pelletized to give a measuring sample. Then, the MT of the sample was measured under the conditions of a resin temperature of 190ºC, an extrusion rate of 15 mm/min and a take-up rate of 10 to 20 m/min using a MT measuring apparatus (produced by Toyo Seiki Seisakusho K.K.) having a nozzle diameter of 2.09 mmø and a nozzle length of 8 mm."

4.3.1 As can be seen from the above cited passage in the patent in suit, a key element for measuring MT of the copolymer [A-1] is the apparatus produced by Toyo Seiki Seisakusho K.K. In order to demonstrate that such a machine and its working was well known to the skilled person, the respondent provided D22 and D23.

D22, an international application filed in the name of the Dow Chemical Company, is contemporaneous with the patent in suit and is concerned with elastic substantially linear olefin polymers. At page 8, lines 22-25 of D22 the measurement is said to be:

"… similar to the "Melt Tension Tester" made by Toyoseiki and is described by John Dealy in "Rheometers for Molten Plastics", published by Van Nostrand Reinhold Co. (1982) on page 250-251)."

The text book referenced in D22 was filed as D23. D23 mentions in the passage bridging pages 250 and 251 the Melt Tension Tester made by Toyoseiki which is said to be similar to the Rheotens. Thus, both D22 and D23 refer to a machine manufactured by Toyoseiki which is, as can be seen from D24, the same company as Toyo Seiki Seisakusho K.K. mentioned in the patent in suit.

The fact that such a machine appeared in a text book published over ten years before the filing date of the patent in suit (as evidenced by D23) and was known to other polymer manufacturers (as evidenced by D22) demonstrates that the machine was indeed widely known in the art and its working would be well understood by the skilled person. Thus, following the detailed information in the patent in suit and applying the common general knowledge relating to the Melt Tension Tester produced by Toyoseiki a skilled person is, in the board's view, in a position to carry out a reliable measurement of the melt tension.

4.3.2 The appellant, on the other hand, has not provided any evidence which could cast doubt on the finding that the Melt Tension Tester made by Toyoseiki was not common general knowledge for the skilled person.

As regards the appellant's argument that there were at least two machines available from Toyoseiki is not supported by the facts on file. Both D22 and D23 refer to "the Melt Tension Tester" which does not imply the existence of two or more Melt Tension Testers made by Toyoseiki. The only other machine mentioned on page 251 of D23 is a "Melt Strength Device". In the board's view, a person skilled in the art trying to measure the melt tension of a copolymer would normally go for the Melt Tension Tester referred to in D23 and not the Melt Strength Device.

4.3.3 Nor was the appellant in a position to demonstrate that other insuperable difficulties existed in determining the MT parameter.

The appellant's argument that the method of measurement for MT was insufficiently disclosed because the length of the spin line to be used in the Melt Tension Tester was not indicated, is not convincing for the following reasons: The length of the spin line is apparently of importance in the Rheotens made by Göttfert. However, it is conspicuous to the board that the MT measurement with the Toyoseiki machine is apparently not identical with a Rheotens test. They might be similar, as stated in D23, but this does not mean that they are identical. In particular, the board has no reason for reading into the word "similar" the concept that they work according to the same principle. On the contrary, D23 does not elaborate on the nature of the similarity. Therefore, issues relating to Rheotens cannot be held against the Melt Tension Tester made by Toyoseiki. Nor has the appellant provided any evidence which would support the alleged lack of sufficiency arising from the missing indication of the spin line length.

The appellant also argued that the relevant passage in the patent in suit indicated an extrusion rate of 15 mm/min and a take-up rate of 10 to 20 m/min but did not indicate at which specific "constant rate" the melt tension should be measured. However, the indication of a range of 10 to 20 m/min for the take-up rate does not give rise to an objection under sufficiency of disclosure for the following reasons: In general, an apparatus for extruding and collecting fibres allows for variation in the rate at which the fibre is collected after extrusion. This rate is referred to as the "take-up rate". When the take-up rate is relatively low, the melt tension of a polymer such as polyethylene is also relatively low. As the take-up is increased, MT is also seen to increase. As can be seen from the plot D19 provided by the respondent (MT versus take-up rate for a typical general purpose polyethylene), further increases in take-up rate lead to a plateau effect and MT becomes essentially constant (the limiting value), despite further increases in take-up rate, over a wide range of take-up rates. The limiting value of MT can be measured at any part of the plateau or constant region of MT versus take-up rate curve which is, according to the respondent, typically in the range of 10 to 20 m/min. As pointed out by the respondent, the skilled person knows very well that this behaviour is generally exhibited by polyolefins and therefore would understand that the reference in the patent in suit to a take-up rate of 10 to 20 m/min simply means that the limiting value of MT should be measured at any convenient take-up rate within the range between 10 and 20 m/min. In order further to support this argument, the respondent has filed Experimental Report 1 (D20) which shows experiments with three different polymers, namely a general purpose polyethylene, a 4-methyl 1-pentene copolymer and a 1-butene copolymer. As can be seen from these experiments, all three polymers show the same plateau in the curves of MT versus take-up rate and for each the limiting value of MT is reached before a take-up rate of 10 m/min and sustained well beyond the take-up rate of 20 m/min. In other words, the experiments show that the value for MT within a take-up range of 10 to 24.7 m/min is virtually independent of the actual take-up rate. Hence, the indication of a range of 10 to 20 m/min for the take-up rate in relation to the MT measurement of the copolymer [A-1] causes no difficulties to a person skilled in the art.

4.3.4 In view of the above, the board comes to the conclusion that the method of measurement for MT is sufficiently disclosed in the patent in suit.

4.3.5 This finding is not at variance with the two previous decisions from this board, namely T 757/03 of 23 June 2006 and T 412/02 of 16 June 2004 (neither of them published in the OJ EPO) because the facts underlying the two previous decisions differ from those of the present case.

In T 757/03, the method of measurement for MT was described in exactly the same manner as in the present case (see point 4.3, above), including a reference to a machine made by Toyo Seiki Seisakusho K.K. The patent proprietor had not established in T 757/03 that the machine made by Toyo Seiki Seisakusho K.K. was widely known in the art and its working would be well understood by the skilled person. Hence, the board decided in T 757/03 that the parameter MT amounted to a newly reformulated and unfamiliar parameter which was insufficiently disclosed (point 5.2.2 and 5.3.3 of the reasons). In the present case, however, the same corporate patent proprietor as in T 757/03 has filed D22 and D23 which clearly demonstrate that the machine made by Toyo Seiki Seisakusho K.K. was common general knowledge. Thus, different facts, namely D22 and D23, result in a different finding on the sufficiency of the measurement of MT.

In T 412/02, Claim 1 had been amended during the opposition appeal proceedings by introducing a relationship between MT and MFR (basically log[MT] >= -0.8 log[MFR] + 0.3). This board, again in a different composition, refused the amendment to Claim 1 under Article 84 EPC - inter alia - because it was not clear which temperature should be applied for the determination of the MT. The application in that case as originally filed referred only to "a melting temperature" but did not indicate the exact test temperature. Apart from the fact that MT is part of the granted claim in the present case and thus not objectionable under Article 84 EPC, the measuring temperature for MT is not an issue in the present case. The relevant passage in the patent in suit (point 4.3, above) clearly identifies this temperature as being 190ºC.

5. Novelty (main request)

5.1 The only relevant document with respect to novelty is D1 which is, as shown in point 2, above, state of the art pursuant to Article 54(3) and (4) EPC.

5.2 D1 discloses various ethylene copolymer compositions comprising one or more ethylene/alpha-olefin copolymers and a low-density polyethylene obtained by high pressure polymerization, a crystalline polyolefin, an olefin type elastomer or a graft modified ethylene elastomer. Comparative Example 5 of D1 discloses in Table 14 a composition comprising the two ethylene/hexene copolymers [A10] and [A11] and the high pressure radical polymerization low-density polyethylene [B10]. The appellant has shown during the opposition procedure that copolymer [A10] and polyethylene [B10] of Comparative Example 5 of D1 meet all the requirements of copolymer [A-1] and polyethylene [B-1] of Claim 1 as granted. However, Claim 1 of the main request contains a disclaimer which removes Comparative Example 5 of D1 form the scope of the claims in suit. Thus, Comparative Example 5 of D1 is not novelty destroying for the claims in suit.

5.3 It has not been shown that any other composition of the examples of D1 would fall within the scope of the claims in suit, but the appellant has raised a novelty objection against Claim 1 of the main request in view of the passage on page 27, lines 9-55 of D1. This passage relates to "the eighth copolymer composition according to the present invention" which is formed from an ethylene/alpha-olefin copolymer composition [C1] comprising the ethylene/alpha-olefin copolymer [A4] and an ethylene/alpha-olefin copolymer [A5] (with the proviso that the ethylene/alpha -olefin copolymer [A4] differs from the ethylene/alpha-olefin copolymer [A5]), and the high-pressure radical polymerization low-density polyethylene [B1]. According to the appellant, component [B1] as disclosed in D1 is identical with component [B-1] of Claim 1 of the main request, at least in the case of a MFR of 0.1 g/10 min, and composition [C1] is identical with component [A-1] of Claim 1 of the main request.

5.3.1 The respondent was of the opinion that the claimed subject-matter was different from D1 because component [C1] of D1 was a blend of ethylene/alpha-olefin copolymer [A4] and ethylene/alpha-olefin copolymer [A5] whereas the copolymer [A-1] in the claims in suit was a single component. However, as pointed out by the appellant, a copolymer is a composition in itself, eg "a copolymer" is composed of polymer molecules of different chain length. Furthermore, it is stated in paragraph [0093] of the patent in suit that the polymerization of [A-1] "may also be carried out in not less than 2 steps having reaction conditions different from each other". In other words, component [A-1] of the patent in suit may be a reactor blend. A similar statement can be found in D1 on page 27, lines 47-49 where it is said that "the ethylene/alpha-olefin copolymer composition [C1] may be prepared by forming the ethylene/alpha -olefin copolymer [A4] and the ethylene/alpha-olefin copolymer [A5] in two or more copolymerization stages having reaction conditions different from each other, or …". Thus, it appears that the difference between the blend [C1] and the copolymer [A-1] is merely a difference in words but not a difference in substance. If the blend [C1] of D1 has the same parameters as [A-1] of the claims in suit, such a composition composed of two copolymers appears to be indistinguishable from a composition composed of "only one" copolymer.

5.3.2 But even if one accepts that the term "an ethylene/C3-20 alpha-olefin copolymer" as used in the patent in suit encompasses blends as disclosed in D1, a detailed analysis of the relevant passage on page 27 shows that this disclosure is not novelty destroying to the claimed subject-matter.

Page 27, lines 19-44 indicates that [C1] preferably has the following properties (c-i) to (c-vi):

(c-i) a density (d) in the range of 0.850 to 0.980 g/cm**(3), preferably 0.890 to 0.955 g/cm**(3), more preferably 0.900 to 0.950 g/cm**(3);

(c-ii) a MFR in the range of 0.1 to 100 g/10 min, preferably 0.2 to 50 g/10 min;

(c-iii) a MT which satisfies the relation:

MT >= 2.2 x MFR-0.84;

(c-iv) a FI which satisfies the relation:

FI > 100 x MFR;

(c-v) a Tm which satisfies the relation:

Tm < 400 x d - 250; and

(c-vi) a quantity fraction W of a decane-soluble portion which satisfies the relation:

in the case of MFR <= 10 g/10 min:

W < 80 x exp(-100(d-0.88)) + 0.1,

preferably W < 60 x exp(-100(d-0.88)) + 0.1, more preferably W < 40 x exp(-100(d-0.88)) + 0.1, and

in the case of MFR > 10 g/10 min:

W < 80 x (MFR-9)**(0.26)x exp(-100(d-0.88)) + 0.1.

The high-pressure radical polymerization low-density polyethylene [B1] has a MFR of 0.01 to 100 g/10 min, preferably 0.05 to 10 g/10 min, more preferably 0.1 to 8 g/10 min as can be seen from the passage bridging pages 18 and 19.

In order to arrive at something falling within the scope of Claim 1 of the main request one would have to select for [C1] a density falling within the range required in Claim 1 (0.890 to 0.935 g/cm**(3)) and the preferred range for W. Furthermore, one would have to select a low MFR for [B1], eg 0.1 g/10 min, so that requirement [B-1](ii) of present Claim 1 is met. According to decision T 653/93 of 21 October 1996 (not published in the OJ EPO, point 3.2 of the reasons), in case of "multiple selection", the question of novelty cannot be answered by contemplating the ranges of various parameters separately. Moreover, one would have to show that the "combined selection" emerges from the prior art.

In the present case, a person skilled in the art had no reason, when applying the teaching of page 27 of D1, to concentrate on the combination of the above mentioned features. Such a combined selection is neither explicitly disclosed in nor derivable from D1. Such a combined selection is also not derivable from Examples 12 and 13 of D1 referred to by the appellant. Although these examples disclose blends of two ethylene/alpha-olefin copolymers in admixture with a high-pressure radical polymerization low-density polyethylene [B10] having a MFR of 0.5 g/10 min, it is not clear whether these examples relate to component [C1] mentioned on page 27 because Tm, which relates to requirement (c-v) of page 27, is not even indicated for the blends of these examples. Hence, these examples cannot be used to support a selection of parameters which lead to a novelty destroying disclosure.

5.3.3 In summary, the passage on page 27 of D1 does not disclose the combination of parameters required in Claim 1 of the main request.

5.4 Consequently, the subject-matter of Claim 1 of the main request, and, by the same token, the subject-matter of Claims 2-7 of the main request is novel over D1.

6. Problem and solution

6.1 The patent in suit is directed in general terms to ethylene copolymer compositions comprising a linear low density polyethylene (LLDPE), ie component [A-1], and a high-pressure low density polyethylene (HD-LDPE), ie component [B-1]. The compositions are excellent in heat stability, melt tension and flowability under the high-shear region, and films obtained from these compositions are excellent in transparency, mechanical strength and blocking resistance (paragraph [0010] of the patent specification). The LLDPE used in the patent in suit is an ethylene/C3-20 alpha-olefin copolymer which has certain defined properties, namely properties [A-1](i)-(vi). These properties are typical of a LLDPE produced using a metallocene-type catalyst. In contrast, "conventional" LLDPE is produced using a Ziegler-type titanium catalyst. The "conventional" LLDPE differs from the one used in the patent in suit insofar as they do not fulfil requirement (vi) defined in present Claim 1.

6.2 D4 discloses ethylene copolymers which are likewise metallocene-produced LLDPEs. The general disclosure of D4 does not disclose each and every feature of component [A-1] of present Claim 1, but Example 12 of D4 discloses in Table 2 an LLDPE made from ethylene and hexene which has exactly the same density, MFR, MT, DSC maximum melting peak and percentage of decane soluble component as polymer A-1-5 in the patent in suit. Although a value of the flow index (FI) is not given in Example 12 of D4, due to the similarity of this example to polymer A-1-5 of the patent in suit it must be assumed that Example 12 has a similar FI as polymer A-1-5. Consequently, the copolymer of Example 12 of D4 must meet all the requirements of component [A-1] of Claim 1 of the main request.

Apart from this structural similarity, D4 discloses technical effects and intended use most similar to the subject-matter claimed in the main request. Thus, D4 refers to the necessity of selecting an ethylene copolymer having a high MT compared with its molecular weight when an inflation film is molded (page 2, lines 20-22) or stickiness of films (equivalent to "blocking" as described in the patent in suit). However, D4 does not disclose the addition of LDPE.

Thus, D4, and in particular a copolymer as described in Example 12 of D4, is considered to represent the closest prior art.

6.3 The above analysis shows that the difference between the compositions of the claims in suit and the prior art lies in the presence of the second component [B-1] which is a LDPE.

As can be seen from Table 3 in the patent in suit, compositions comprising components [A-1] and [B-1] (Examples 1-3, 5 and 6) exhibit a higher MT than the corresponding component [A-1] alone. A higher MT normally manifests itself in an improved mouldability (Table 3, last column). Furthermore, it is apparent from Table 3 that the compositions comprising [A-1] and [B-1] maintain to a high degree the excellent mechanical properties (such as "film impact" and "impact retention") shown by the LLDPE [A-1]. This latter aspect is quite important to the performance of the claimed subject-matter. In contrast, a "conventional" Ziegler-titanium LLDPE does not show such an effect when blended with LDPE. As can be seen from Comparative Example 1 in the patent in suit, a blend comprising "conventional" LLDPE and LDPE has much worse mechanical properties than the LLDPE alone.

Thus, contrary to the opinion of the appellant, the objective technical problem with respect to the closest prior art does not lie solely in the provision of compositions having further improved melt tension (or mouldability). Rather, the objective technical problem has to be seen in the provision of compositions having further improved melt tension (or mouldability) while maintaining the excellent mechanical properties of the prior art polymers.

In view of the examples provided in the patent in suit, the results of which are summarized in Table 3, the board is satisfied that the above defined objective technical problem is solved by the features required in Claim 1 of the main request.

7. Inventive step

7.1 It remains to be decided whether the proposed solution, ie the addition of a LDPE, is obvious from the available prior art in order to solve the objective technical problem. The relevant documents for the assessment of inventive step are D4, D10 and D14.

7.2 D4 is the only citable prior art which is concerned with metallocene-produced LLDPE (see point 6.2, above). This document itself does not suggest to add a LDPE as a further component, let alone to add LDPE in order further to improve the mouldability of the LLDPE while maintaining its good mechanical properties.

7.3 The appellant basically relied on a combination of the closest prior art with D10 and D14. D10 describes the practice of film manufacturers to blend LDPE with LLDPE. D14 is an extract from an encyclopaedia relating to LDPE. Under the section "Products and Uses" on page 420, D14 discusses blends of LDPE with LLDPE as being especially useful for film applications. Furthermore, on page 422, section "Blends and Coextruded Film", D14 discloses that in film applications LLDPE is blended with 25-50%, and sometimes with 75%, of LDPE homopolymers in order to increase the rate of extrusion and the melt strength of the polymer during the film blowing operation and provide better properties.

7.4 However, this line of argumentation is not convincing for the following reasons:

Firstly, D10 and D14 deal with "conventional" LLDPE used by industry at that time which were produced using Ziegler-type titanium catalysts. Thus, although these documents may be contemporaneous with the date of the patent in suit, they do in fact not contain any information which is of relevance to the "new" type of LLDPE used as component [A-1] in present Claim 1. It takes several years for a newly developed material to progress through the experimental and testing stages to eventually become a common industry practice which might be presented in documents such as D10 and D14. It is hard to see why the skilled person would consider such documents when he is faced with a problem relating to "new" LLDPE, namely further improving the mouldability of this "new" LLDPE without sacrificing its mechanical properties. Normally, it is not permissible to assume that the "new" LLDPE would behave in the same way as the "concentional" LLDPE. Product performance and properties of a blend comprising the "new" LLDPE can only be determined by testing the specific blend.

Secondly, D10 and D14 do not address a key element of the objective problem, namely maintaining the excellent mechanical properties of the LLDPE. D10 and D14 cannot provide any hint in this direction because it is a fact that the addition of LDPE to a "conventional" LLDPE considerably decreases the mechanical properties as can be seen from Comparative Example 1 in the patent in suit (see also point 6.3, above). Thus, neither D10 nor D14 can provide a hint to the objective technical problem with regard to maintenance of the mechanical properties. Moreover, it appears that a combination of D4 with D10 and/or D14 is based on hindsight. Without the knowledge of the patent in suit a person skilled in the art would not consider such a combination.

7.5 The respondent requested that D12 and D13 not be admitted into the proceedings because it was not clear that these documents were made available to the public before the priority date of the patent in suit.

As regards D12, which was briefly referred to in the statement of grounds of appeal, the appellant did not rely on this document any more in the oral proceedings before the board. In fact, this document became virtually superfluous in view of the filing of D14 at the appeal stage. Thus, there was no need to pursue this issue.

As regards D13, the appellant declared in the oral proceedings that he did not want to introduce this document any more and, consequently, did not rely on it any more. Hence, there was no need to pursue this issue.

7.6 Summing up, neither D4 alone nor the combination with D10 or D14 would lead the skilled person to add LDPE to the "new" LLDPE in order to improve its melt tension (or mouldability) while maintaining its excellent mechanical properties.

Consequently, the subject-matter of Claim 1 of the main request, and, by the same token, the subject-matter of Claims 2-7, is based on an inventive step (Article 56 EPC).

8. Since the respondent's main request is allowable, any discussion of the auxiliary requests is superfluous.