“1. A glass reinforcement strand whose composition comprises the following constituents in the limits defined below, expressed as percentages by weight: SiO 2 58-63% Al 2O 3 12-20% CaO 12-17% MgO 6-12% CaO/MgO ≤ 2, preferably ≥1.3 Li 2O 0.1-0.8%, preferably ≤ 0.6% BaO + SrO 0-3% B 2O 3 0-3% TiO 2 0-3% Na 2O + K 2O ˂ 2% F 2 0-1% Fe 2O 3 ˂ 1% wherein the composition has an Al 2O 3 + MgO + Li 2O content equal to 23% or higher.”
“Other attempts at increasing the mechanical strength of glass strands have been made, but generally to the detriment of their fiberizability, the processing then becoming more difficult or imposing the need to modify existing fiberizing installations. There is therefore a need to have glass reinforcement strands having a cost as close as possible to that of E-glass and exhibiting mechanical properties at a performance level comparable to that of R-glass.”
“Lime (CaO) is used to adjust the viscosity and to control the devitrification of the glasses. The CaO content preferably lies in the range from 13 to 15%. Magnesia (MgO), like CaO, acts as a viscosity reducer and also has a beneficial effect on the specific Young's modulus. The MgO content lies in the range from 6 to 12%, preferably from 7 to 9%. The CaO/MgO weight ratio proves to be an essential factor for controlling devitrification. The inventors have identified that a CaO/MgO ratio not exceeding 2, but preferably greater than 1.3, promotes crystallization of the glass in several phases (anorthite: CaO.Al 2O 3.2SiO 2 and diopside: CaO.MgO.2SiO 2, or even forsterite: 2MgO.SiO 2 or enstatite: MgO.SiO 2) which enter into competition for growth at the expense of the liquid phase. This competition has the effect of limiting the maximum growth rate of the crystalline phases and therefore reducing the risk of the glass devitrifying, and of allowing it to be fiberized correctly.”
“In the glass composition of Table IV other substituents may also be present in small amounts typically below 1 percent each. In general, Fe 2O 3 is present in quantities of 0.1 to 0.5 percent, TiO 2 between 0.2 to 0.8 percent, K 2O between 0.1 and 0.5 percent and also if the glass composition desired is only a boron-free composition, then a small amount of fluorine up to 1 weight percent can be used in the composition.”
“…the approach to be adopted to the interpretation of claims containing a numerical range is no different from that to be adopted in relation to any other claim. But certain points of particular relevance to claims of this kind do emerge from the authorities to which I have referred and which are worth emphasising. First, the scope of any such claim must be exactly the same whether one is considering infringement or validity. Secondly, there can be no justification for using rounding or any other kind of approximation to change the disclosure of the prior art or to modify the alleged infringement. Thirdly, the meaning and scope of a numerical range in a patent claim must be ascertained in light of the common general knowledge and in the context of the specification as a whole. Fourthly, it may be the case that, in light of the common general knowledge and the teaching of the specification, the skilled person would understand that the patentee has chosen to express the numerals in the claim to a particular but limited degree of precision and so intends the claim to include all values which fall within the claimed range when stated with the same degree of precision. Fifthly, whether that is so or not will depend upon all the circumstances including the number of decimal places or significant figures to which the numerals in the claim appear to have been expressed.”
“There is normally no reason to suppose the patentee when he set the limits of his monopoly knew of a particular piece of prior art which is therefore irrelevant in deciding what those limits are. Of course the position is different if the prior art is specifically acknowledged in the patent. The purposive construction would lead to a construction of a claim which did not cover that acknowledged prior art: it can hardly have been the inventor's purpose to cover that which he expressly recognises was old.”
“… the matter relied upon as prior art must disclose subject-matter which, if performed, would necessarily result in an infringement of the patent. That may be because the prior art discloses the same invention. In that case there will be no question that performance of the earlier invention would infringe and usually it will be apparent to someone who is aware of both the prior art and the patent that it will do so.”
"[6] The Respondent also submitted in the course of oral proceedings that, as a matter of law, it was not permissible to cross the legal borderline between novelty, in the strict sense of a clear and specific disclosure in a prior document of the particular narrow combination of claimed ranges in question on the one hand, and the obviousness of choosing such a combination of ranges from that prior art document containing a disclosure of the broader range, on the other hand. In this connection the Board wishes to set out the general legal principles that apply to so-called "selection" patents. The most important one is that under the EPC patents are not granted for inventions for the sole reason that they are "selections", but only for new and inventive subject–matter of certain defined kinds (Articles 52 to 57 EPC). Selection is in fact only a conceptual tool, used principally in the field of chemical inventions, for deciding novelty in certain situations, which novelty can, however, only be decided under the express provisions of Article 54, and in particular Articles 54(2) and (3) EPC. Article 54 (2) EPC defines the state of the art as comprising "everything made available to the public by means of written or oral description, by use or in any other way"
"(1) (a) Identify the notional "person skilled in the art" (b) Identify the relevant common general knowledge of that person; (2) Identify the inventive concept of the claim in question or if that cannot readily be done, construe it; (3) Identify what, if any, differences exist between the matter cited as forming part of the "state of the art" and the inventive concept of the claim or the claim as construed; (4) Viewed without any knowledge of the alleged invention as claimed, do those differences constitute steps which would have been obvious to the person skilled in the art or do they require any degree of invention?"