Sappi Fine Papers (Pty) Ltd v ICI Canada Inc (Formerly CIL Inc)

• Jurisdiction: South Africa

Sappi Fine Papers (Pty) Ltd v ICI Canada Inc (Formerly CIL Inc)
1992 (3) SA 306 (A)

1992 (3) SA p306

Citation	1992 (3) SA 306 (A)
Court	Appellate Division
Judge	Corbett CJ, E M Grosskopf JA, Nestadt JA, Vivier JA, Nicholas AJA
Heard	February 24, 1992; February 25, 1992; February 26, 1992
Judgment	March 30, 1992

Flynote : Sleutelwoorde B

Patent — The specification — Construction of — To be construed with reference to state of knowledge of those skilled in the art — Relevant C state of knowledge being that obtaining at time of publication of specification, ie at time of filing application for registration — Court to be instructed by expert evidence as to state of art in field to which invention relates at relevant time — Court to be placed, as far as possible, in position of skilled addressee — Court thus to adopt purposive approach to interpretation of patents. D

Patent — The specification — Construction of — Skilled addressee — Who is — Someone expected to bring reasonable intelligence to bear upon language of specification — Skilled addressee, while not required to struggle unduly with specification, must not adopt attitude of studied obtuseness.

E Patent — Convention patent — Revocation of — On grounds of misrepresentation — Patents Act 37 of 1952, s 23 (now repealed) — Section 23(1)(i) and (k) providing for revocation in case of misrepresentation — Section 23(1)(k), providing for specific case of F convention patent, laying down additional requirements in subparas (i) and (ii) — Patent in suit a convention patent — No suggestion that requirements of subparas (i) and (ii) met — Applicant for revocation nonetheless pursuing case for revocation on basis of alleged disconformity between application in convention country and patent in suit — Court holding that, while alleged disconformity could fall under wide and G general wording of s 23(1)(i), generalia specialibus non derogant rule supporting conclusion that Legislature intended para (k) to deal specifically with disconformity as to invention in convention application — Disconformity as to invention in case of convention application and consequential misstatements in application thus not constituting ground for revocation under s 23(1)(i). H

Headnote : Kopnota

A patent specification must be construed with reference to the state of the knowledge of those skilled in the art and, according to English authority and, it appears, the South African law, the relevant state of knowledge is that obtaining at the time of the publication of the specification, ie at the time of filing of the application. In order to I enable the Court to construe a specification properly, it must be instructed by expert evidence as to the state of the art in the field to which the invention relates as it was at the relevant date. The Court must be placed, as far as is possible, in the position of the skilled addressee. The skilled addressee is someone who is expected to bring reasonable intelligence to bear upon the language of the specification and who, while not required to struggle unduly with it, is to make the best of it and not to adopt an attitude of studied obtuseness. The Court should, J thus, adopt a 'purposive' approach to the interpretation of patents.

1992 (3) SA p307

A Wood has to be pulped, by mechanical or chemical means, in order to produce paper. Delignification, in terms of chemical pulping, involves the removal of lignin from the wood. This is achieved by a process known as 'cooking', which entails the wood being placed in a vessel, known as a 'digester', together with a chemical agent in an aqueous solution, known as the 'pulping liquor'. The contents of the digester are then heated under pressure for a chosen period, during which period the pulping liquor penetrates the wood, reacts with the lignin and takes it into solution, B leaving the wood fibres as lignin free as possible. The wood fibre and liquor are then separated. A problem inherent to the chemical pulping process is the degradation of the cellulose fibres themselves, resulting in lower yields of cellulose and a reduction in the strength of the pulp produced. One of the two best-known processes using an alkaline pulping liquor produces a 'stronger' pulp, but also produces unacceptable air pollutants as a side-effect; the other, while not producing unacceptable C pollutants, is inclined to degrade cellulose faster and consequently produces an inferior pulp.

The respondent's patent concerned a process for the delignification of lignocellulosic material (ie the removal of lignin from, inter alia, wood in order to produce cellulose suitable for the manufacture of paper products). In its patent specification, the respondent described the objects of its invention as providing an increased yield of cellulosic pulp with a lower pollution potential. The delignification process D protected by the patent entailed the treatment of lignocellulosic material in a closed reaction vessel with an alkaline pulping liquor, which pulping liquor contained a specific range of percentage (by weight based on the material) of a cyclic keto compound selected from a specified group of compounds, the treatment taking place at a maximum temperature in a stated range for a stated range of time.

The process used by the appellant at one of its mills seemed, prima facie, to fall within the process protected by the patent, using as it did one of E the selected cyclic keto compounds, namely anthraquinone (AQ), in an alkaline pulping liquor. The appellant's denial that it had infringed the respondent's patent was based upon the chemical reactions which occurred during the 'cooking' process: the conversion of AQ, which was virtually insoluble in aqueous systems and thus did not dissolve into the pulping liquor when added to the digester, into semi-anthraquinone (semi-AQ), then F into anthrahydraquinone (AHQ) by reduction and, subsequently, by oxidation when AHQ was converted back to AQ, possibly via semi-AQ. Unlike AQ, AHQ is highly soluble in an alkaline solution. The conversion of AQ into AHQ accordingly enabled the latter to go into solution, to penetrate the wood chips in the digester, to react with the lignin and to facilitate and speed up the delignification process. AHQ also counteracted the degradation of the cellulose.

The appellant's defence was that: (a) claim 1 of the respondent's patent, properly interpreted, meant that during the process of treatment the G alkaline pulping liquor had to contain a prescribed concentration of a cyclic keto compound and, more particularly, one of those included in the group of selected compounds; (b) while at its mill the compound initially added to the alkaline pulping liquor before digestion commenced was one of the selected compounds (AQ), as the treatment progressed the AQ was converted to semi-AQ and AHQ, neither of which was a cyclic keto compound; H and (c) it was not possible at any given time during the process of digestion, or immediately upon its termination, to say how much, if any, AQ was still contained in the pulping liquor.

The appellant led expert evidence, which was undisputed, with reference to the process at its mill to the effect (i) that the major delignification took place at maximum temperature; (ii) that during the period while the contents of the digester were heating to maximum temperature the AQ was progressively converted to AHQ, so that by the time that maximum I temperature was reached the amount of AQ left in the pulping liquor would not be substantial and at the end of time at temperature (ie the period for which the contents of the digester were maintained at maximum temperature) would be minimal; (iii) that during the process of digestion it was not possible to determine at any particular time what the concentration of AQ in the pulping liquor was; and (iv) that after the termination of the digestion process and the emergence of the liquor from J the digester the semi-AQ and AHQ, immediately

1992 (3) SA p308

A upon contact with air, were oxidised and converted to AQ, thus preventing any measurement at that stage in order to determine what the concentration of AQ during the digestion process had been.

Held (per Corbett CJ; EM Grosskopf JA, Nestadt JA, Vivier JA and Nicholas AJA concurring), that at the relevant date the skilled addressee would have known that a high pressure built up in a digester while cooking was in progress and that there inevitably would be problems in then B introducing pulping liquor or additives, or in removing additives in order to measure quantities.

Held, further, that it could be inferred from the evidence of the respondent's expert witness that the insolubility of AQ in aqueous systems and the solubility of AHQ had been well-known facts at the relevant date.

Held, further, that it appeared, too, that at least part of the reduction-oxidation reaction involving the conversion of AQ into AHQ would have been known.

C Held, further, accepting the above to have been the state of the art at the relevant date, that the following conclusions reached by the Court a quo had, in the main, been well founded: (a) that a skilled addressee would have been surprised to have been told that the addition of one of the selected cyclic keto compounds had to take place when the interior of the digester had reached high temperature and pressure; (b) that it followed that any reasonable reader of the claim would have realised that, in order to 'treat' the wood chips, the AQ had to change from AQ into AHQ, D and that a reference in the patent claims to AQ had to be a reference to AQ in some other form, for example the reduced form, AHQ; and (c) that if it were taken into account that AHQ could not be measured, especially not in a closed vessel at high temperature and high pressure, it had to follow that the...