Monday, 14 October 2013

T 389/11 – Blessed Are The Pure

This examination appeal case is interesting because the Board found the claimed product of higher purity to be both novel and inventive.

Product-by-process claim 1 before the Board read:
1. A metal powder obtainable by a process for producing metal powders comprising the steps of:
  • providing a hydride powder of a first metal being selected from the group consisting of tantalum, niobium and alloys of said metals with each other or one or both of them with other metals, the hydride having an oxygen content of under 300 ppm;
  • mixing said metal hydride with a metal having a higher affinity for oxygen and heating the mixture;
  • removing the metal having a higher affinity for oxygen from the metal, to form a powder of the first metal with an oxygen content of less than 100 ppm.

[3.1] [… C]laim 1 has been drafted as a product by process claim in order to comply with A 76(1). It is, however, well established that a product per se must be novel and inventive, and is not rendered so merely because it is made by a new and inventive process (see Case Law, 6th Edition, II.B.6.2 [II.A.7.2 in the 7th edition]). For a process feature to have any relevance in a product claim it must result in a discernible physical characteristic in the product.

In the present case, claim 1 defines a powder of tantalum, niobium and their alloys with an oxygen content of less than 100 ppm. These are the features of the product of claim 1, hence it is necessary to determine if such a product is disclosed in the prior art.

[3.2] The Examining Division (ED) held that the claimed powder lacks novelty over D1, which concerns powders of tantalum, niobium or their alloys having an oxygen content of less than 300 ppm.

In reaching its decision, the ED argued that the claimed oxygen content (less than 100 ppm) is a sub-range of that disclosed in D1 (less than 300 ppm). Since the criteria for novelty of a sub-range (i.e. sufficiently narrow, sufficiently far removed from prior art values and a purposive selection, as set out in T 279/89) were not met, the claimed subject-matter lacked novelty.

[3.3] The problem addressed by the present invention is to reduce as far as possible the oxygen content in the metal, as it is seen to be an impurity element. The approach to cases dealing with the purity of a material is set out in T 803/01 (see in particular points [4.6.3] and [5.3]), and is summarised in section I.C.4.1.4 of the Case Law (6th Edition) [now I.C.5.1.4]. To establish novelty and inventive step, it must be shown that prior art techniques have failed to achieve the claimed degree of purity. Thus, the assessment of novelty and inventive step of the product is inextricably linked to the purification process.

[3.4] The process defined in claim 1 (an example of which is given in Example 3 in the description) differs from that of D1 principally in that a metal hydride having an oxygen content of under 300 ppm is used as the starting material, rather than a metal powder having an oxygen content of less than 1000 ppm, as disclosed in D1 […].

The process of D1 is said to result in a product having an oxygen content preferably between about 100 and about 300 ppm […]. The ED emphasised […] that the value “about 100 ppm”, being an end point of a range, is specifically disclosed and cannot be distinguished from the upper value of the range defined in claim 1 (100 ppm). However, the examples in D1 give oxygen contents of 155, 140, 135, 130 ppm for tantalum and 175 ppm for niobium; these are clearly above the level of 100 ppm. The skilled person reading D1 would thus not reach the conclusion that the process of D1 results in a product having an oxygen level below 100 ppm.

The claimed powder is therefore novel.

[3.5] Starting from D1, the problem to be solved is to reduce the oxygen content yet further. The proposed solution of starting with a hydride instead of a metal leads to a material having an oxygen content of less than 100 ppm, as demonstrated in Example 3 of the application.

[3.6] Document D2 discloses a process for reducing the oxygen content in tantalum and/or niobium (columbium) materials. Although Examples 1 to 10 and 12 all concern metallic tantalum as the starting material, Example 11 starts from tantalum hydride. The hydride powder is heated in hydrogen gas, and the water vapour formed by the reaction of hydrogen with the oxygen in the powder is then “gettered” by a more oxygen-active metal than tantalum, in this example, zirconium. However, the oxygen content is not reduced to less than 100 ppm by the process; it is 1140 ppm in the hydride starting powder and is present in a comparable amount in the tantalum powder end product […].

Whereas the process of D1 involves heating metal powder with a metal having a higher affinity for oxygen, the process of D2 involves heating a hydride powder in a hydrogen atmosphere, as described above. D1 and D2 thus concern different processes and it is unreasonable to combine the teachings of these documents. Consequently, tantalum hydride is not an obvious alternative to tantalum metal as a starting material for the process of D1.

In addition, even if D1 and D2 were to be combined, there is no indication in D2 that use of a hydride starting powder results in an oxygen content below 100 ppm.

[3.7] The subject-matter of claim 1 is not obvious in light of D1 and D2. There is no indication in the available prior art that a powder of tantalum, niobium and their alloys can be produced with an oxygen content of less than 100 ppm. The metal powder of claim 1 is thus novel and has an inventive step.

Should you wish to download the whole decision, just click here.

The file wrapper can be found here.

Today I would like to pose my readers a question: It is established case law (I believe) that “in general, a document disclosing a chemical compound and its manufacture makes available this compound to the public in the sense of A 54 in all grades of purity as desired by a person skilled in the art”. I would agree with that statement if available ... to the public in the sense of A 54 was replaced by obvious to the skilled person in the sense of A 56. The statement as it stands somewhat hurts my understanding of novelty. I find it hard to accept that all degrees of purity are actually disclosed, although I would be willing to endorse that obtaining a specific degree of purity would be obvious to the skilled person, unless there are specific circumstances that require inventiveness to reach certain degrees of purity. Where is the error in my reasoning?


Anonymous said...

Having reviewed the case law cited ( I.C.5.1.4], I just feel that the board missed to state here that the present case is an exceptional case where it is proven that it has not been possible to manufacture such pure powder until now (T990/96).

And I understand from 3.1 that the wording of the claim (product by process) has been chosen to meet A76(1). I deduct from this sentence that the board would have granted a product claim as well, if there had been support in the application.

TB said...

The error in your argumentation below is common to many.

A (chemical) compound is a single entity that cannot be divided lest it is destroyed. So once it is known, it stays known, even when it is mixed with other (chemical) compounds. H2O e.g is a compound and you can add another compound NaCl to make a mixture of these two compounds. This however is not salt water, yet. You need an Avogadros number (give or take) of H2O molecules to make water, but this action does not change the chemical composition of H2O and adding NaCl to water does not make the H2O-molecules impure but it does create salt water. Wikipedia has a good definition of compounds for further reading.

The problem to the chemist however is usually the reverse. He starts out with salt water and wishes to prepare pure liquid water (i.e. An Avogadro's number of H2O molecules without any other constituent compounds in the water). But what he has is a mixture of an Avogadros number of H2O molecules mixed with an Avogadros number of NaCl ions. Achieving your goal from this starting point is pretty tough, since your working against entropy. So a good process for purifying a compound in a mixture can be worth quite a lot of money. But given your starting point, you'll never reach perfection.

In relation to the below, what you have are metals. They consist, by definition, of an Avogadros number of atoms and so may form mixtures with other atoms which creates the need for purification of the metal. However no atoms are thereby transmuted.

Nevertheless, given that the Boards are pretty savvy and do understand about chemical compounds, I never understood from the case law why the Boards had to include purity into the discussion in relation to the novelty of chemical compounds since purity is only a topic when discussing mixtures.

oliver said...


I found your comment very enlightening.

Thank you very much.

Anonymous said...

What TB says is right, IMO. In chemistry, especially if you deal with macromolecules, there is no 100% purity. There are always remnants of the things you need to prepare the compound, e.g. catalyst, diluent, monomer, undesired byproduct, etc. So, even if the claim says "compound X", in fact you have a mixture of mainly one compound with a lot of other minor stuff. Often, after production, a purification step is necessary. Now if there are well- known means to get a certain purity, let us say 95%, then one might consider the compound with that purity known. But if then someone finds a method to get a higher purity, that compound of e.g. 98% purity may well be novel. It would depend on the exact circumstances in that particular field. That higher purity might make the difference between the necessity of having a further purification step after production or not, involving an extra factory process unit or not. A whole lot of money. But do not underestimate the commercial interest of even an apparently minor improvement either, because if you deal with tons and tons of product, every ppm improvement in purity may mean a lot of money. So purity is a real issue in chemistry patents and not a simple one.

Anonymous said...

The problem I have with this case is that the Board has ordered a patent to be granted rather than referring the matter back to the ED for further examination. This is particularly worrying since such powdered metals with 100 ppm oxygen are well known in the art. The method of production may be different but not the product.

Suleman said...

Just to comment on the writer's question at the end of the post: inventive step is a tricky beast, especially on complicated cases where you can show reasons why the skilled person would not attempt to make a substance at a particular degree of purity. Using inventive step to argue a substance at a different purity is not patentable would sometimes be complicated (and burdensome) for the EPO, and so they've saved themselves the trouble with the 'disclosed at all grades of purity' assumption. From my experience of what happens in EPO examination and opposition this approach is likely to lead to less mistakes and more certainty and justice for all parties, even though it's a bit artificial.

Anonymous said...

Free beer, anyone?