T 0608/01 07-04-2005

1. The appeal is admissible.

Amendments

2. Amended claims 1 and 8 go back to process claim 7 and product claim 2 as filed, respectively. Amended claim 8 has been made dependent on claim 1, so that the filamentary yarn is obtainable by the process steps of claims 1 to 7. Amended claim 11 is based on claims 16 and 17 as filed. Amended claim 12 corresponds to claim 18 as filed except for the amended reference back. The further amendments to claims 1 and 8 have a basis in the application as filed as follows:

- claim 1, step 1): "60°C" (claim 11);

- claim 1, step 2): "80°C - 120°C" (claim 12);

- claim 1, step 3): "160°C" (page 49, line 10);

- claim 8, feature iv): page 34, last three lines.

2.1 The amendments to the claims have not been objected to by the appellants. The board sees no reason to take a different position. Thus, the amended claims meet the requirements of Article 123, paragraphs (2) and (3), EPC.

Insufficiency of disclosure

3. The former main objections to insufficiency of disclosure were based on the calculation of the mesomorphous portion and the reference to the Tg. The first objection has been overcome by cancelling granted claim 1 and maintaining granted claim 2 as an alternative definition of the yarn produced by the claimed process. The second objection has been overcome by replacing the Tg in the process claim by specific temperature values. Consequently, those objections are overcome.

3.1 The appellants, however, argued that the temperature window for drawing the yarn was not clearly disclosed, since the patent specification did not indicate whether or not the drawing temperature referred to the temperature of the yarn itself, the heated rolls, the heating plates and/or hot air.

3.2 The question to be answered under Article 83 EPC is whether or not the claimed process can be reproduced by a person skilled in the art by taking into account the information in the patent in suit and common general knowledge.

3.2.1 According to amended claim 1, the quenching temperature in step 1) is 25 to 60°C, the temperature in step 2) is 80 to 120°C, the thermal heat treatment step 3) is effected at 160°C to 210°C and in step 4) the relaxation temperature is 140°C. Furthermore, it is specified that in step 2) said "undrawn yarn" is drawn, in step 3) that the "obtained drawn yarn" is thermally heat treated and in step 4) that the "thermally treated yarn" is relaxed.

3.2.2 As confirmed by the technical expert of appellant 01, the claimed process steps normally include rolls for spinning, drawing, thermal heating and relaxation similar to those as illustrated in Figure 2 of D9. According to Figure 2 of D9, after quenching of the filaments, the spun filament is drawn by a feeding roll 1 having a specified temperature, then passed over two pairs of rolls 2 and 3 both running at the same velocity but at a higher speed than roll 1. In that second (last) drawing step a pair of rolls 5 and 6 is used, which normally has the highest temperature of the rolls. In the final step, the rolls 7 and 8 run at a lower velocity so that a relaxation occurs. Appellant 01 agreed that the thermal heating step 3), which is neither a drawing step 2) nor a relaxation step 4), will be carried out with rolls running at the same velocity (draw ratio: 1:1).

3.2.3 Thus, from the above it follows that process steps 1) to 4) are quite separate process steps carried out at different process conditions and temperatures, which do not overlap.

3.2.4 The claimed process is illustrated in the patent in suit by twenty examples and ten comparative examples, in which detailed process conditions for steps 1) to 4) are specified, in particular spinning speed, drawing ratio, relaxation ratios and different temperatures to be used in those steps. In particular, the drawing is carried out in two steps, wherein the temperatures indicated refer to the "draw zone" (see tables 1 and 2). Since it is practically impossible to measure directly the temperature of a fast-running yarn as confirmed by D17 (page 11, lines 6 to 8), the drawing temperature cannot refer to the yarn itself.

3.2.5 According to the patent in suit, at a too high drawing temperature (above 120°C) fine crystals are formed before the orientation of the molecular chains and accordingly the drawability is degraded. At a too low temperature (below 80°C) the molecular chains lose their mobility whereby efficiency of drawing is low (page 11, lines 39 to 42). Thus, the skilled person will maintain the temperature of the medium in the draw zone within the claimed range so that these disadvantages are avoided.

3.2.6 Consequently, the skilled person gets sufficient information from the patent in suit as to how to set the temperature conditions of the medium in the drawing zone. On the other hand, the appellants have not provided any experimental evidence showing that the skilled person, with the guidance of the patent in suit and common general knowledge, would be unable to carry out the claimed process and to arrive at yarns having satisfactory properties. The onus of proof in this respect lies, however, with the opponents (appellants) (T 219/83, OJ EPO 1986, 211), which they failed to discharge.

3.3 The appellants further argued that the strength of the cord defined in claim 11 had no concrete meaning, since the total fineness of the tire cord was not defined.

3.3.1 According to the patent in suit, filaments having a total fineness of 1000 denier (111 tex) (page 12, line 53) and a yarn with a fineness of 111 tex (1000 denier) (page 13, line 18) are used to produce a tire cord under specified process conditions (page 13, lines 23 to 31, tables 3 and 4). For that purpose the yarns are twisted 49 times/10cm in Z direction and then 49. times/10cm in S direction before doubling them together (page 13, lines 25 to 27). The properties of such tire cords are presented in Table 3, which reflect the properties of the tire cord according to claim 11. Hence, the skilled person is able to reproduce the tire cord for which the specific properties are indicated.

3.3.2 Furthermore, it has not been shown by experimental results that the skilled person was unable to reproduce such tire cords having the features i) to iv) as claimed. The onus of proof in this respect lies with the opponents (appellants) (T 219/83, supra), which they failed to discharge.

3.3.3 The question whether or not the cord fineness should be indicated in claim 11 concerns an objection of clarity under Article 84 EPC rather than an objection of insufficiency under Article 83 EPC. Since that objection did not arise out of any amendment made, the argued missing indication in the claim cannot be objected to under Article 84 EPC, which is not a ground of opposition (Case Law, supra, VII.C.10.2).

Novelty

4. Appellant 01 did not raise any novelty objections, during oral proceedings, against the amended claims of the main request. The board sees no reason to take a different position. In addition, the novelty of the claimed subject-matter becomes apparent from the discussion of inventive step below.

Inventive step

Problem and solution

Process claim 1

5. The patent in suit inter alia concerns a process for the production of polyester filamentary yarn. Such processes are known from the prior art, in particular from D16 and D11, which the parties and the opposition division considered as an appropriate starting point for assessing inventive step of the claimed process. Since claim 1 concerns a process claim and since appellant 01 started from D16 as the closest state of the art, it is appropriate to start with D16 first.

5.1 The patent in suit aims at a process for the production of a polyester filamentary yarn which exhibits excellent fatigue resistance and dimensional stability both before and after it has been incorporated in a rubber matrix even under the conditions where it is subjected to repeated fatigue behaviour at high temperatures (at least 210°C) (page 4, lines 16 to 19).

Starting point D16

5.2 D16 discloses a process for production of a dimensionally stable drawn polyethylene terephthalate multifilament yarn having filaments of at least 2.5 denier per filament comprising the steps of:

(a) extruding a polyethylene terephthalate polymer melt through a spinnerette having a plurality of extrusion orifices to form filaments;

(b) advancing the extruded multifilament yarn first through a delay zone then through a quenching zone to solidify the filaments in a controlled manner;

(c) withdrawing the solidified multifilament yarn from the quenching zone at a desired spinning speed V;; whereby steps (a) through (c) are performed under conditions to form a partially-oriented multifilament yarn having an undrawn birefringence (Delta/n/u) of at least 0.020 and wherein Delta/n/u = Rf V2.0 IV2.4 where IV is the intrinsic viscosity of the undrawn yarn and is at least 0.80 and Rf is at least 9.0 x 10/-3; then (d) hot drawing the partially-oriented multifilament yarn (claim 1).

5.2.1 According to Examples 1 to 4 of D16, a two stage drawing step and a relaxation step are used. In Examples 1 and 3 a PET polymer is spun through a heated sleeve and quenched in a radial quench stack. The spun yarn is subsequently drawn on a panel similar to Figure 2 with a roll 1 maintained at 90°C. The yarn is drawn 1.5/1 to unheated rolls 2, 3 with a normal ambient temperature of 40-50°C, then drawn 1.6/1 from rolls 2, 3 to rolls 5, 6 maintained at 200°C and then the yarn is relaxed to rolls 7, 8 at 1 to 1.5 percent. Rolls 7 and 8 have an operating temperature of 150°C. The drawn yarn is taken up at 2.98 km/min. The drawn yarn is 1004 denier and IV is 0.92 dl/g. In claimed step 4) the relaxation temperature (140°C) is lower and the relax ratio (3 to 6%) is higher than in the relaxation stage of D16.

5.2.2 In Examples 2 to 4, the spun yarn is first drawn 1.4/1 between rolls at 90°C and unheated rolls, then drawn 1.15/1 between these and rolls maintained at 220°C. The drawn yarn is then relaxed at 3% to rolls maintained at 135°C. The drawn yarn is taken up at 4.6 km/min. The drawn yarn is 924 denier and IV of the undrawn yarn is 0.92 dl/g. Since the relaxation conditions in Examples 2 and 4 cover those of claimed step 4), Examples 2 to 4 have more features in common with the claimed subject-matter than Examples 1 and 3. Hence, it is appropriate to use Examples 2 and 4 as starting point.

5.2.3 The drawing steps in Examples 2 and 4 of D16 cover temperatures of 90°C, 40 to 50°C and 220°C. In particular, in those examples the higher temperature of 220°C is specifically described as part of the drawing process, but not as separate thermal heat treatment different from the drawing and the relaxation conditions as claimed. Contrary to D16, the temperatures in drawing step 2) as claimed are limited to 80 to 120°C.

5.3 Since heated rolls 5 and 6 having a temperature of 220°C form part of the drawing step, they cannot be a thermal heating step 3) separate from a drawing step 2) and a relaxation step 4) in the sense of the steps of claim 1.

5.3.1 But even if the temperature of 220°C was interpreted as a kind of thermal treating step, that specific temperature would be outside the claimed range of 160 to 210°C.

5.4 The temperature of the thermal heating is one of the important factors to determine the structure of the yarn because in this thermal treatment a yarn with nearly completed orientation is treated. The temperature is required to be in the range of 160 to 210°C. When the temperature exceeds 210°C, which is the case in Examples 2 and 4 of D16, the network structure characteristic of the claimed invention i.e. the development of intermicrofibrillar tie molecules cannot be achieved and the orientation of the crystalline portions is greatly increased and the orientation of the amorphous region is decreased. Therefore, the lowering of strength due to abnormal crystal growth in the subsequent dipping process cannot be minimized (patent in suit, page 12, lines 17 to 21).

5.4.1 Examples 1 to 20 of the patent in suit illustrate the production of a yarn having a three phase microstructure, when using the above defined process steps 1) to 4) (Table 1, pages 15 to 17). This microstructure is evident from yarns having a crystalline orientation function (fc) below 0.94 and an amorphous orientation function (fa) of at least 0.60 as also specified in claim 8, since in those yarns besides the crystalline and amorphous portions a pseudo-crystalline portion of mesomorphous portion exists (page 7, lines 29 to 31). Those yarns show in addition a crystal volume of 152 nm3 or less (Example 16; claim 7). Furthermore, by those process conditions yarns having a relative high shrinkage of 8 to 15% and a maximum thermal stress of less than 0.5 g/d will be obtained (see tables 1 and 2). In particular, the yarns produced by the claimed process show a "decrease" in the thermal stress behaviour beyond 210°C.

5.4.2 On the other hand, comparative examples 1 to 10 illustrate yarns which do not achieve the above mentioned properties when process conditions outside the claimed range are used. In particular, when the temperature of the second drawing zone is 220°C and/or the heat treatment is above 210°C, the desired three phase microstructure, crystallite size and crystal volume cannot be achieved (see Table 2, page 20, in particular comparative examples 9 and 10). Furthermore, the shrinkage of the yarn produced by the comparative examples is lower than that obtained by the claimed process (see comparative examples 9 and 10 having a shrinkage of 5.9 and 5.6, respectively). In addition, in all yarns produced according to the comparative examples the thermal stress behaviour "increases" beyond 210°C.

5.4.3 When the exemplified yarns obtained by the claimed process are incorporated in the tire cord under the specified conditions of claim 12, a combination of (i) high strength at 10% elongation of at least 100 Newtons, (ii) low shrinkage S of at most 3.5% obtained upon dry heat treatment at 177°C during 2 minutes under a dead weight loading of 20 g, (iii) high strength at 10% elongation after the treatment in ii) above, L, of at least 65 Newtons, and (iv) a coefficient of dimensional stability L/S, of at least 20, can be achieved (page 21, Table 3). Furthermore, the strength retention when tested on a tire before and after 48h rotation at an inner tube pressure of 3.5 kg/cm2, rotation speed of 850 rpm and tube angle of 80°C is 94% or higher (see page 14, lines 6 to 8; Table 3). However, all exemplified comparative examples tested do not provide the above combination of tire cord properties and have in particular a strength retention of at most 90%.

5.4.4 From the results in tables 1 to 3 it can be gathered that yarns obtained by the claimed process have a distinct crystalline microstructure with the potential, when incorporated into a tire cord, to provide dimension stable products having low shrinkage at most 3.5% and maximum thermal stress of 0.06 to 0.09, although the starting yarns have a relative high shrinkage of above 10 (Example 9) to 12.4% (Example 12) and a maximum thermal stress of 0.28 (Example 9) to 0.48 (Example 1). In comparison thereto, tire cords according to comparative examples 15 to 20 which have been produced under the same dipping conditions do not show the desired combination of properties, in particular a lower fatigue resistance and strength retention efficiency although the lower starting shrinkage of the yarn of comparative examples 3, 5, 9 and 10 appears to be more promising in that respect than that of the yarns obtained by the claimed process.

5.5 Appellant 01 argued that the comparative examples have been carried out under unrealistic conditions and that no valid comparison to the state of the art has been made.

5.5.1 Comparative examples 9 and 10 use a temperature in the second drawing zone of 220°C and heat treatment temperature of 240°C and a high relax temperature of 180°C. The temperature of 220°C in the second drawing zone of Example 2 and 4 of D16 lies within that range. There are a lot of examples and comparative examples showing that the process conditions as claimed are critical for achieving the claimed effect in the final tire cord and that outside the claimed process condition these properties cannot be achieved. Hence, it has been made plausible that improved properties over the state of the art can be achieved, because in D16 the critical process conditions have not been met.

5.5.2 Whilst no direct comparison is on file which reproduces the exemplified process conditions of D16, there are, however, no process conditions disclosed in D16, under which the tire cords should be produced, making a direct comparison with the state of the art possible.

5.5.3 In this respect, appellants 01 and 02 have not shown by experimental evidence anything which might invalidate the plausible results shown in the patent in suit.

5.5.4 From the above it follows that the problem solved over D16 can be seen in providing a process for producing a yarn which, when incorporated into a tire cord shows an enhanced fatigue resistance and an improved strength retention.

Starting point D11

5.6 D11 discloses a polyester fibre composed of a polyester comprising ethylene terephthalate units as the main recurring units and having an intrinsic viscosity of at least 0.90, wherein the amorphous orientation degree is in the range of from 0.30 to 0.55 and the crystal melting point is at least 265°C (claim 1). The fibre has a crystal volume of at least 4.0 x 10/5 Å3 (400 nm3) a dry-heat shrinkage factor at 210°C of less than 6% and a long-period spacing is at least 160 Å (claims 2, 3. and 6).

5.6.1 The fibres according to D11 are produced at a take up speed of the undrawn fibre of 2000 to 6000 m/min (page 8, line 26), which is comparable to the claimed spinning speed. The cooling is effected by blowing air at room temperature (page 7, line 33). After spinning, the fibre is first drawn at a temperature in the range of Tg + 15°C to Tg + 50°C (page 9, lines 7 to 9), corresponding to 95 to 130°C, if Tg of PET is assumed to be 80°C. Thereafter, the fibre is subjected to a subsequent drawing stage. If a heat treatment is carried out, it is effected at a temperature in the range of (fusing temperature - 50°C) to (fusing temperature - 110°C) at a relax ratio to 10 to 20% (page 9, lines 17 to 24). The fusing temperature of PET is at least 265°C (D11, page 3, line 29) so that the temperature of that heat treatment is within the range of 155 to 215°C.

5.6.2 In Example 3 of D11 a melted polyester at about 300°C is extruded from a spinneret, spun at a spinning speed of 3500 to 6000 m/min (Table 2), cooled and solidified by blowing cooling air maintained at 25°C. The undrawn fiber is supplied to a roller heated at 85°C and subjected to a first stage drawing between this roll and a take-up roll at a first draw ratio (DR1) and is then subjected to second stage drawing through a gas bath maintained at 325°C at a second draw ratio (DR2). Then, the fibre is subjected to a relax heat treatment at a third drawn ratio (DR3) by using a roller heated at 130°C and a gas bath at 330°C (page 18, lines 33 to page 19, line 5). The relax ratio in only one of fourteen runs is 5% (run 12), in all other runs 7% and above. In none of these exemplified runs is a heat treatment separate from the drawing and relaxation steps carried out. Furthermore, that relaxation step includes a gas bath having a temperature of 330°C which is far above the relaxation temperature used in step 4) as claimed.

5.6.3 According to Example 1 of D11, the draw ratio DR3 may be 1.00 (runs 3 and 8 to 10). This separate heat treatment is effected at a roller heated to 130°C and a gas bath maintained at 330°C. Even if in those runs a separate heat treatment is effected, the temperature thereof is above 210°C. Furthermore, in D11 there is no hint to a combination of steps 3) and 4) as claimed.

5.6.4 According to the patent in suit, when the relaxing temperature is greater than 140°C, the yarn will initiate the creation of defects in the crystalline structure or destruction of the same upon the application of heat in the subsequent dipping process. When the relax ratio is more than 6 percent, the strength efficiency may be decreased and the resulting lowering of shrinkage may be so small that the effect cannot remain in the dipped cord (page 12, lines 34 to 39).

5.6.5 A too high temperature of 220 to 240°C in the heat treatment and/or in the relaxation steps changes the microstructure of yarn considerably as shown by the crystalline and amorphous orientation function, the long period spacing and the crystal volume (patent in suit, Table 2, comparative examples 3, 5, 8 and 9). According to D11 the crystal volume of the yarns is preferably at least 400 nm3 to avoid that a degradation of the strength is readily caused (page 5, lines 4 to 9). Hence, the crystal volume of the yarns obtained by the claimed process (Table 1, pages 16 and Table 2, page 18) is more than two and a half times smaller than that of the yarns obtained by D11. Furthermore, the thermal stress behaviour of Example 3, run 12 of D11, "increases" beyond 210°C as shown by Figure 2, whilst in all exemplified yarns obtained according to the claimed process the thermal stress behaviour beyond 210°C shows the opposite effect (Table 1, pages 15 to 18).

5.6.6 From the above it follows that the process conditions in D11 are more distinct from the claimed process conditions than D16 and provide yarns having a crystal microstructure quite different from the claimed subject-matter. Furthermore, there are no examples in D11, which illustrate the behaviour of those yarns when incorporated into a tire cord under specific conditions.

5.6.7 Thus, considerations similar to those according to D16 (points 5.5 to 5.5.4 above) apply mutatis mutandis to D11 so that the problem to be solved over D11 can be formulated accordingly as outlined under point 5.5.4 above.

Product claim 8

5.7 D10 discloses a polyester yarn comprising primarily polyethylene terephthalate for use in reinforcing rubber goods and having the following properties:

(a) an intrinsic viscosity of at least 0.91,

(b) a tenacity of at least 8 g/d,

(c) E2.25 of 4.5 percent or less,

(d) DeltaHmf of at least 11.5 cal/g,

(e) (Tmf - TmF) of at least 20°C, and

(f) an amorphous orientation function of 0.75 or less, wherein E2.25 is the elongation under a load of 2.25 g/d, DeltaHmf is the amount of heat at the melting peak in differential scanning calorimeter (DSC), Tmf is the melting point measured by DSC under a tension of 0.05 g/d, and TmF is the melting point measured by DSC under no tension (claim 1). The crystalline orientation function fc of the yarn generally exhibits a value of about 0.94 (page 3, lines 49 and 50).

5.7.1 According to the example of D10, the spun yarn is cooled with air at 18°C and taken up at a speed of 2000 m/minute to a take-up roller which is heated to 85°C. The undrawn yarn is given a first stage drawing to a draw ratio of 1.45 between the heated take-up roller and an unheated No. 1 Nelson roller. Then, between the No. 1 Nelson roller and a No. 2 Nelson roller heated to 240°C, the yarn is passed through 400°C steam jet apparatus to effect a second stage drawing. Then, between the No. 2 Nelson roller and a conditioning roller which was heated to 100°C, the yarn is subjected to a relaxation ratio of 1.3 to 4.8 (Table 1). However, only one of the twelve examples (Example 11) shows a relaxation ratio between 3 and 6% as claimed.

5.7.2 D10 does not provide any indication of the claimed long period value and the shrinkage of the yarn. The long period value is a parameter reflecting the size of the crystal and amorphous regions so as to prevent the dimension deformation as such shrinkage by heat (patent in suit, page 8, lines 6 to 9).

5.7.3 Furthermore, the process conditions specified in the example of D10 are in many aspects different from those of the claimed process conditions. In particular, the exemplified spinning conditions of 2000 m/min at a quenching temperature of 18°C are outside the claimed range. Since the quenching temperature is less than 25°C, the filament is too quickly quenched and thus the tension at the solidification point may be decreased so that it may be difficult to obtain a highly oriented undrawn yarn (patent in suit, page 11, lines 23 to 30). Furthermore, in D10, the drawing conditions at very high temperatures by using rollers heated to 240°C and steam heated to 400°C cannot provide the microstructure of yarn as obtained by the claimed process as illustrated in the Examples 1 to 20 and comparative examples 3 and 5 of the patent in suit (tables 1 and 2). In particular, those comparative examples do not exhibit the crystalline microstructure as specified by the long period value, the crystallite size, the crystal volume and its shrinkage which characterize the yarn obtained by the claimed process. Thus, it has not been shown that the process conditions in D10 are suitable to provide a yarn showing a decrease in thermal stress behaviour beyond 210°C as illustrated in tables 1 and 2 of the patent in suit.

5.7.4 Furthermore, although the conditions for measuring the shrinkage of the tire cord in D10 are not fully comparable to those of Table 3 of the patent in suit, they are measured at similar temperatures of 177 and 180°C respectively. Whilst the tire cord obtained by yarns according to D10 shows a heat shrinkage of 4.2 to 6.8% (Table 1, line N), the tire cord according to the patent in suit shows a shrinkage of less than 3.5% (Table 3; claim 11). The appellants have not shown anything to the contrary by experimental evidence.

5.7.5 From the above it is plausible that the claimed yarn exhibits a decrease in thermal stress behaviour above 210°C and provides, when incorporated into a tire cord, a lower shrinkage.

5.7.6 Thus, the problem solved over D10 can be seen in providing a polyester filamentary yarn which exhibits an improved fatigue resistance and dimensional stability when incorporated in a rubber matrix.

Obviousness

6. It remains to be decided whether or not the claimed subject-matter is obvious having regard to the documents on file.

Process claim

6.1 In D16, according to which a proper selection of process variables results in desired yarns exhibiting improved "dimensional stability" (page 9, lines 13 to 16), there is no hint to combine the teachings of Examples 1 and 3 with Examples 2 and 4. In particular, a simple lowering of the drawing temperature from 220°C according to Example 2 to 200°C according to Example 1 would not result in the claimed process, since those examples neither describe a drawing step within a temperature range of 80 to 120°C nor a separate heat treatment 3) as defined in claim 1. Thus, the claimed process steps for solving the technical problem are not made obvious from D16 alone.

6.2 Although in D11 four examples of Table 1 describe a thermal heat treatment without drawing and one example in Table 2 discloses a heat treatment under the claimed relaxation conditions, there is no incentive to combine these features in order to arrive at the claimed steps 3) and 4). Furthermore, the temperature conditions in all examples include a second drawing step comprising a heat roll at 130°C and a gas bath at 330°C resulting in temperatures at the drawing stage outside the claimed range. Having regard to the fact that the thermal stress increases at temperatures beyond 210°C as shown in Figure 2 of D11, whilst yarns obtained by the claimed process show an opposite behaviour under those conditions, there is no incentive in D11 to modify the process conditions in a direction as claimed. Furthermore, there is no indication in D11 for modifying the process steps of D16 in order to improve the fatigue resistance and retention of strength of the tire cord. Consequently, the claimed process is not made obvious when considering D16 and D11 in combination.

6.3 D9 discloses a process for spinning an organic synthetic melt spinnable polymer comprising the steps of extruding the polymer through a spinneret; passing the filaments from the spinneret through an elongated zone; maintaining the filaments at a temperature above the glass transition of the polymer over a distance of about 3 meters or greater within the zone; and thereafter converging the filaments (claim 1). The filaments have a spun denier per filament of 3-20 (claim 3). The filaments are quenched with a hot gas having a temperature no greater than 260°C, preferably 230°C (claims 5 and 6). The fibres of polyesters having an intrinsic viscosity of at least 0.85 (Examples IV, V and VII) were produced at a spinning speed of 3000 to 5800, preferably 3200 to 3800 m/min (page 6, lines 20 to 24) and have a crystalline portion of 10 to 43% (page 6, line 46). The draw ratio is about 1.65 for a spun yarn made at about 3800 m/min and the optimum draw roll temperature is 240 to 245°C (page 6, lines 58 to 58). In Example IV the draw rolls are maintained at a temperature of 180 to 255°C. In Example V, a single stage drawing by using an ambient feed roll and a 245°C draw roll are applied.

6.3.1 Since temperatures of 220°C and above in the drawing and/or heat treatment step result in yarns which show an increase in thermal stress behaviour beyond 210°C (see Table 2 of the patent in suit, comparative examples 3, 5, 9 and 10) and since nothing to the contrary has been shown, it is plausible that the exemplified yarns produced in accordance with D11 will show a similar effect. Furthermore, yarns of those comparative examples will not show the high strength retention and dimensional stability of the yarns obtained by the claimed process when incorporated into tire cords (Tables 3 and 4).

6.4 Since D9 does not disclose any separate thermal heat and relaxation step and since the exemplified temperatures of the drawing step are quite outside the claimed range, there is no incentive in D9 to modify the teaching of D16 in a direction of the claimed process conditions in order to solve the problem posed.

6.5 D2 discloses a continuous melt-spin process for the simultaneous spin-drawing of high performance polyester multifilament yarn with an intrinsic viscosity of at least 0.90, a toughness of at least 0.40 grams per denier and a work loss of less than 0.04 inch-pounds when cycled between a stress of 0.6 gram per denier and 0.05 gram per denier at 150°C measured at a constant strain rate of 0.5 inch per minute in a 10-inch length of yarn normalized to that of a multifilament yarn of 1000 total denier, which comprises the steps of

(a) feeding prepolymer to a first finisher vessel operated at 280°C or less for a period sufficient to increase the intrinsic viscosity to at least 0.4,

(b) transferring polymer from said first finisher vessel to a second finisher vessel while maintaining said polymer below about 280°C,

(c) maintaining said polymer in said second finisher vessel at 280°C or less for a period sufficient to achieve an intrinsic viscosity of at least 0.95,

(d) removing said polymer of intrinsic viscosity of at least 0.95 from said second finisher and supplying said polymer to an extrusion spinnerette at a temperature above the polymer melting point, maintaining said polymer at said spinnerette for a residence time no greater than one and one-half minutes and at a temperature no greater than 325°C prior to spinning, then

(e) spinning the polymer under conditions to produce an undrawn yarn having a birefringence of at least 0.01 and drawing said yarn to produce said high performance polyester multifilament yarn (claim 1).

6.5.1 The process conditions of D2 mainly concern the spinning conditions and the drawing should be effected between rolls at temperatures above the glass transition temperature (i.e. 80°C) to with 85% of the maximum draw ratio (column 7, lines 4 to 6). However, D2 does not mention any process conditions specified in steps 3) and 4) as claimed. Thus, there cannot be any guidance in D2 to modify the teaching of D16 in the direction of the claimed process.

6.6 The process conditions according to D10 (see point 4.7) are quite different from those required by the claimed process and would not suggest the claimed subject- matter even when considering D10 and D16 in combination.

6.7 No other documents were referred to by appellant 01 at the oral proceedings when discussing inventive step. Since the further prior art documents cited during the proceedings are even more unrelated to the claimed subject-matter than those already discussed, they could not suggest the claimed subject-matter either. Thus, the board has no reason to go into more detail in that respect. Hence, when starting from D16 the claimed subject-matter of process claim 1 is not rendered obvious by the cited prior art.

6.8 When starting from D11, run 12 of Example 3 can be considered as the nearest starting point. However, the yarn in run 12, Example 3 of D11 shows a behaviour of the thermal stress at a temperature beyond 210°C opposite to that of the yarns produced according to the claimed process. Furthermore, the drawing step of D11 includes a gas bath maintained at 325°C and the relax treatment uses a roller heated at 130°C and a gas bath maintained at 330°C, which temperature conditions are different from the temperature conditions of claimed steps 2) and 4). Since also the other examples of D11 use high temperature conditions similar to those of run 12, they do not provide any incentive, to modify the conditions in a direction of the claimed process steps 2) to 4), let alone to its combination.

6.8.1 Having regard to D2, D9, D10 and D16 the same considerations as outlined above (Reasons, points 6.1, 6.3, 6.4 and 6.5) apply mutatis mutandis when starting from D11 as the closest state of the art. In particular, there is no incentive in those prior art documents to modify the teaching of D11 in the direction of the claimed process in order to solve the problem posed. Thus, the claimed subject-matter of the process claim is not obvious from the cited prior art documents and involves an inventive step.

Product claim 8

6.9 Having regard to product claim 8, D10 does not disclose or suggest how yarns having the claimed long period value and shrinkage may be produced to modify those yarns so that, when incorporated into a tire cord, improved shrinkage and dimensional stability may be achieved. In particular, the exemplified process conditions in D10 at rollers heated to 240°C lead the skilled person in a direction opposite to the claimed subject-matter and do not provide yarns which show a decrease in the thermal stress behaviour beyond 210°C as illustrated in Table 1 and Figure 3 of the patent in suit.

6.9.1 Although D2 discloses a yarn B having a long period value of 11.8 within the claimed range, its crystal orientation function is 0.95 and its shrinkage at 177°C is 5.7% (tables I and II), both features being outside the claimed range. Furthermore, D2 does not disclose any specific heat treatment or relaxation conditions which, according to the patent in suit, are necessary to provide a yarn which, when incorporated into a tire cord, solves the problem posed. Consequently, the skilled person gets no incentive from D2 to modify the yarns according to D10 in a direction of the claimed product.

6.9.2 In D9, Example VII, yarns are produced which show a long period value within the claimed range (Table VII, runs 1 and 5 to 8). However, those yarns have been produced from PET having a low IV of 0.63, whilst yarns having an IV of 0.92 exhibit a long period value of 1.83 to 1.92 far outside the claimed range (Table VII, runs 9 to 11). There is no indication in D9, showing how yarns can be produced from high IV PET which exhibit a long period value as claimed, let alone in combination with the other claimed features, in order to solve the problem posed (see Reasons, point 6.4). Thus, D9 does not add anything to the disclosure of D10.

6.9.3 Since the product claims make reference to the process claims, the same considerations discussed in respect of D11 and D16 apply mutatis mutandis to the claimed yarns as outlined above (Reasons, points 6.1 and 6.2). Consequently, claim 8 is not rendered obvious when starting from D10 as the closest state of the art.

6.10 Since the tire cord according to claim 11 is referred back to product claims 8 to 10, since process claim 12 is dependent on process claims 1 to 7, and since the tire claim 13 is referred back to claim 11, the same considerations discussed in respect of the process and product claims 1 to 10 apply mutatis mutandis to claims 11 to 13 (Reasons, points 6.1 to 6.9 above).

6.11 From the above it follows that the appellants failed to show that claimed subject-matter is made obvious by the cited prior art. Hence, the claims according to the main request involve an inventive step.