Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1999-09-03
2001-11-27
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S392000, C065S432000, C065S433000, C065S447000, C065S448000, C065S450000, C065S453000
Reexamination Certificate
active
06322888
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
In the field of reinforcing yarns and composites, the present invention relates to a process for the production of sized glass yarns, as well as to the yarns obtained and to the composites made from the said yarns.
2. Description of the Background
Reinforcing glass yarns are manufactured, in a known manner, from molten glass streams flowing through die orifices. These streams are drawn in the form of continuous filaments and these filaments are then assembled as base yarns, which are then collected.
Before being assembled in the form of yarns, the filaments are usually coated with a sizing composition by passing them through a sizing member. This deposition of sizing is very important: on the one hand, it allows the yarns to be obtained and, on the other hand, it allows these yarns to be used efficiently in the production of composites. Sizing has indeed the following usual functions: it protects the yarns from abrasion and thus prevents them from breaking during their manufacture and, possibly, during their use; it furthermore allows the combination of yarns with organic and/or inorganic materials, by facilitating, in particular, the wetting and/or impregnation of the yarns by these materials. In most cases, sizing also enhances the adhesion between the glass and the material to be reinforced and allows composites to be obtained with improved mechanical properties.
It is thus important for the deposition of sizing to be carried out efficiently and under the best possible conditions, so that the sizing can carry out its functions correctly.
The sizings most commonly used are aqueous sizings (containing more than 85% by weight of water) which are easy to deposit, the water then being removed by drying. Sizing compositions are normally chosen so as not to undergo chemical reactions at room temperature (during storage) and under the die (for example polymerization of the sizing, thereby making it impossible to deposit). On the other hand, they can optionally be chosen to polymerize under the effect of a treatment subsequent to the deposition on the filaments. This is, in general, a heat treatment at a temperature above 100° C., carried out after collecting the yarns. This polymerization of the sizing makes it possible to obtain integral yarns (whose filaments are solidly attached to each other) and which can be manipulated, this integrity being especially desired in textile applications in which the yarns are subjected to high mechanical stresses.
Since each additional treatment of the sized yarns, in particular each energy-consuming treatment, results in additional cost with regard to the yarn manufacturing process and is liable to generate defects on the yarns obtained (problems of migration of the components of the sizing on a winding of heat-treated yarns, for example), it is economically advantageous to find means for reducing the importance or number of these treatments.
However, no process currently exists which is both very cost-effective (especially insofar as it does not require an expensive energy treatment of the sized yarns during their manufacture) and which makes it possible to obtain, in good yields (in particular at high rates, with a limited level of breakage and with no variation in the quality of the yarns which would necessitate rejection of some of the products), an entire range of sized yarns for various applications, these sized yarns having uniform coating and characteristics over their entire length.
SUMMARY OF THE INVENTION
The object of the present invention is thus to provide a process for the production of sized glass yarns of constant quality in favourable yield, this process being both cost-effective and affording the best possible yarn-coating conditions. The object of the present invention is also to provide a process which makes it possible to obtain, with these same advantages, an entire range of glass yarns which can be used in various applications. The object of the present invention is also to obtain yarns which can be manipulated directly and which can be used to prepare composites and which have a uniform coating over their entire length.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
This object is achieved by the process according to the invention, in which the conditions necessary for obtaining the desired yarns with the advantages described above are defined. In this process, streams of molten glass are drawn, these streams coming from orifices located at the bottom of one or more dies, in the form of one or more fans (or sheets) of continuous filaments, and the filaments are then assembled into one or more yarns which are collected on one or more moving support(s), this process consisting in depositing a first stable composition, having a viscosity of between 0.5 and 250 cP, onto the surface of the filaments, in depositing at least a second stable composition, supplied separately of the first and having a viscosity of between 0.5 and 300 cP, onto the surface of the filaments or of the yarn(s), at the very earliest during the deposition of the first composition and at the very latest during the collection of the yarn(s), the difference in viscosity between the compositions deposited being less than 150 cP, the mixture of the compositions deposited furthermore having the functions of a sizing composition and being capable of polymerizing at room temperature.
The process according to the invention has several advantages: firstly, it makes it possible to dispense with the treatments (heat treatments or irradiation) usually used to polymerize sizing compositions on glass yarns, which represents a considerable economy. In the same way, it avoids the treatment of certain effluents, the release of effluents generally being associated with the polymerization heat treatments carried out. The process according to the invention is of improved production efficiency, the yarns obtained especially being of uniform quality over their entire length. Furthermore, it allows better control over the sizing polymerization reactions carried out on the yarns and limits the risks of these yarns breaking. This process also reduces the risks of irregular migration of sizing components on the yarn and/or the risks of coloration of the yarns or of deformation of the windings associated with certain yarn treatments (such as drying). Moreover, the process can be applied with the same advantages to the preparation of different types of sized yarns for the purpose of various applications. It also makes it possible to obtain yarns coated with novel compositions, based on systems not existing in current sizings on account of their reactivity and instability. The process according to the invention thus makes it possible to broaden considerably the field of sizings and opens the way to novel products and novel applications.
According to the invention, the term “glass yarns” is understood to refer to yarns based on glass, i.e. not only yarns formed solely of glass filaments but also yarns formed of glass filaments and of organic filaments, in particular thermoplastic filaments. In the latter case, during the drawing of the glass filaments, the organic filaments are extruded and entrained simultaneously (or the organic yarns coming, for example, from windings are supplied simultaneously), the paths followed by the glass filaments and the organic filaments (or yarns) converging on one another before the said filaments are assembled into at least one mechanically-entrained composite yarn.
The glass filaments can be drawn in the form of a fan from a die or in the form of several fans from one or more dies and can be assembled into one or more yarns. The draw rate of the glass filaments in the process according to the invention is generally between 8 and 75 m/s, usually between 10 and 60 m/s. In general and preferably according to the invention, the compositions (in particular the first composition) are deposited on the filaments once cooled below 90° C., that is to say when the temperature of these filaments is below 9
Gibello Bruno
Moireau Patrick
Roubin Marc
Gray J. M.
Kelly Cynthia H.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Vetrotex France
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