T 2090/12 (Surface area/IBIDEN) 19-01-2015

1. Admittance of E1 and E1'

1.1 The evidence E1 and its translation E1' were filed on 19 December 2014, i.e. after the oral proceedings had been arranged. Hence, it was within the discretion of the board whether to admit them into the proceedings (Article 13(1) and (3) RPBA).

1.2 E1 and E1' were filed in reaction to the preliminary opinion set out in the communication in which the board expressed its concerns with regard to sufficiency of disclosure.

1.3 For the above reasons, and because the amendments to the appellant's case did not raise issues which the board or respondent could not reasonably be expected to deal with without adjournment of the oral proceedings, the board exercised its discretionary power under Article 13(1) and (3) RPBA and admitted documents E1 and E1' into the proceedings.

2. Sufficiency of disclosure - all requests

2.1 Statutory law and jurisprudence of the boards of appeal

2.1.1 A European patent must disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art (Articles 83 and 100(b) EPC).

2.1.2 According to the established jurisprudence of the boards of appeal, the requirement of sufficiency of disclosure is met only if the invention as defined in the independent claim can be performed by the person skilled in the art within the whole area claimed without the burden of an undue amount of experimentation, taking into consideration common general knowledge and the whole information content of the patent in suit (see also T 435/91, OJ 1995, 188, Reasons 2.2.1, third paragraph; T 409/91, OJ 1994, 653, Reasons 2, first paragraph, penultimate sentence).

2.1.3 The requirement of sufficiency of disclosure is not met in particular if the patent lacks guidance and this lack of guidance cannot be overcome drawing on common general knowledge (cf. also T 575/05, Reasons 1, fourth and fifth paragraphs; T 817/11, Reasons 2.3 to 2.6).

2.2 Lack of guidance in the present case

2.2.1 According to the appellant the features "specific surface area of the cell wall" (main request and auxiliary requests 1 to 3) and "the specific surface area of the particles forming the cell wall" (auxiliary request 4) all related to the grains in the state after the formation of the cell walls and thus after sintering, since only during sintering of the ceramic material were grains formed and grown. Thus, it was clear to the skilled person that the expression referred to the specific surface area of grains obtained by grinding a sample of the cell wall.

2.2.2 According to the respondent, even if the skilled person knew that the feature "specific surface area of the cell wall" related to the particles obtained after grinding a sample of the cell wall, there was a lack of sufficiency of disclosure. This grinding method was not specified in the patent in suit, and nor was the method to be used to measure the specific surface area of the particles obtained after grinding.

2.2.3 The board, in favour of the appellant, construes the features "specific surface area of the cell wall" (main request and auxiliary requests 1 to 3) and "the specific surface area of the particles forming the cell wall" (auxiliary request 4) to refer to the grains forming the cell wall in the state after sintering (cf. paragraphs [0023], [0123], [0124], and [0127] of the patent in suit).

However, the board cannot identify any passage in the patent in suit that would support the appellant's view that the skilled person would know that, for the purpose of measuring the specific surface area of those grains, a sample of the cell wall needed to be ground. What is more, there is no information in the patent in suit concerning

(i) the grinding method to be used and

(ii) the method for determining the surface area of the particles obtained after grinding.

2.2.4 The board thus concludes that there is a lack of guidance regarding the method to be applied in order to determine the specific surface area of the grains forming the cell wall in the state after sintering.

2.3 Drawing on common general knowledge

2.3.1 The question that arises is whether this lack of guidance could be overcome by drawing on common general knowledge.

In support of its contention that the skilled person would know which grinding method was to be applied, the appellant referred to ISO standard 8213 (document D15) and to test report E1.

2.3.2 Document D15

D15 refers to a number of possible grinding/crushing techniques (see sections 4.2 to 4.2.1.5). As is known to the skilled person, the particle size (distribution) and hence the specific surface area are highly dependent on the type of grinding/crushing technique applied. Consequently, even assuming that the skilled person would have consulted D15 he would have been at a loss as to the type of grinding/crushing technique to be applied.

2.3.3 Test report E1

In E1 (page 5, section 3.1 to page 6, section 3.2 of E1'), milling using an agate mortar is repeated "until the powder for which measurement of specific surface area was possible was achieved". This type of milling is carried out three times before a milling is carried out for a specific time using 18 g of sample, 500g of ball stone of 5 mm diameter made of zirconia and 100 ml of ethanol.

Specific surface area vs milling time|

Milling

time(minutes) |Sintered body particle A |Sintered body particle B |

Total

surface

area (m**(2)) |Sample

weight

(g) |Specific

surface area

(m**(2)/g) |Total

surface

area (m**(2)) |Sample

weight (g) |Specific

surface area

(m**(2)/g) |

0 |1.01 |1.447 |0.6999 |1.20 |1.774 |0.676 |

30 |0.65 |1.442 |0.449 |0.89 |1.365 |0.652 |

180 |0.73 |1.315 |0.559 |0.86 |1.007 |0.859 |

As can be seen from the above table (see page 7 of E1'), the specific surface area for sintered body particles A decreases with time from 0.699 at t=0 minutes to 0.449 m**(2)/g at t=30 minutes and increases again to 0.559 at t=180 minutes, i.e. a value below the initial value. The skilled person would expect the specific surface area to increase with time, since continued milling would normally result in smaller particles with a higher specific surface area.

For the board, it is not at all plausible that the specific surface area decreases with time during milling. Asked by the board at the oral proceedings, the appellant could not explain the data and referred to possible agglomeration phenomena occurring during milling. For the board, there is no indication whatsoever that the milling using a ball mill in E1 would lead to agglomeration rather than to disintegration of the particles.

Considering the data for sintered body particles B contained in the above table, the board observes that the specific surface area again decreases from 0.676 m**(2)/g at the beginning to 0.652 at t=30 minutes, but then increases to 0.859 m**(2)/g at t=180 minutes.

In the case of both sintered body particles A and sintered body particles B, the specific surface area changes significantly over time. It follows that the appellant's contention that "the specific surface area of the ceramic sintered bodies does not change substantially with the milling time" is not supported by the facts as evidenced by E1.

2.3.4 As a consequence, it is not possible to conclude from either E1 or D15 that the measured surface area does not depend on the grinding method used, and in particular on the duration of the grinding.

2.3.5 According to the appellant, the skilled person could verify whether or not a ceramic sintered body fell within the scope of the claims. The test results provided in E1 showed that usual equipment available on the market enabled the skilled person to arrive at values falling within the claimed range.

The board is not convinced by this argument. There is no evidence that would support the view that common general knowledge would prompt the skilled person to determine the specific surface area of the particles forming the cell wall according to the method set out in E1. Many other ways of milling/grinding, including different types of ball mills, different kinds of ball stones, different milling times and so forth, are conceivable for the skilled person. Obviously, not all of these different conceivable milling/grinding techniques would lead, for the same sample, to a specific surface area within the range claimed. It is therefore also not sufficient to show that a specific grinding and milling method leads to values within the range claimed.

2.3.6 The board thus concludes that the the skilled person cannot overcome the lack of guidance identified at 2.2.4 supra by drawing on common general knowledge.

2.4 It follows that the requirement of sufficiency of disclosure is not met for the main request or any of the auxiliary requests (Articles 83 and 100(b) EPC).