Compositions: ceramic – Ceramic compositions – Glass compositions – compositions containing glass other than...
Reexamination Certificate
2000-01-24
2002-10-22
Group, Karl (Department: 1755)
Compositions: ceramic
Ceramic compositions
Glass compositions, compositions containing glass other than...
C501S036000, C216S097000, C428S359000, C428S362000
Reexamination Certificate
active
06468932
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an Al
2
O
3
-containing, high-temperature resistant, silica-based glass sliver with highly textile character, products of a like glass sliver, and their use.
2. Description of the Related Art
The production of textile products on an inorganic fiber basis in accordance with various processes has been known for a long time (Ullmanns Enzyklopädie der technischen Chemie, Bd. 11, Verlag Chemie, Weinheim, 1989). For the current manufacture of the like products, SiO
2
fibers on the basis of silica or silica glass are being used, with a distinction being made with respect to the single fibers into the primary forms of filament (monofilament, fiber having an unlimited length and a defined fiber cross-section) and staple fiber (fiber having a finite length and a defined fiber cross-section) (Z. Ges. Textilind. 69, 839 (1967), DE patent No. 42 40 354).
In DE patent No. 42 40 354 it was described that a linear textile fiber product—the sliver (staple fiber ribbon)—is a starting material for the production of staple fiber yarns and twisted yarns suited for processing into further follow-up products such as woven or interlaced fabrics. According to this patent specification, a silica sliver has become known which consists of silica staple fibers having a length of 50 to 1000 mm and which is characterised by an individual fiber strength of 20 to 50 cN/tex, a sliver adhesion of 2 to 20 N, and a sliver fineness of 50 to 2000 tex. This textile fiber product is obtained in a three-stage process combining dry spinning of soda water glass filament yarn, formation of soda water glass sliver according to the withdrawal cylinder process, and transformation into silica sliver in an aftertreatment section. It is hence based on a soda water glass solution and exclusively contains SiO
2
and Na
2
O in various weight proportions. Use of a siliceous sliver produced in such a manner for the production of corresponding staple fiber yarns and twisted yarns, cords, and woven and interlaced fabrics is claimed for application temperatures above 400-500° C. Information on the behavior of such siliceous sliver at temperatures in the vicinity of 1000° C. is, however, not provided. This material is moreover not offered on the market.
Also known for a long time has been the production of glass slivers according to the withdrawal cylinder process (DE examined patent application No. 1 270 748, DE patent No. 1 199 935, DE published patent application No. 195 05 618). In these methods, molten glass emanates from spinning nozzles located at the bottom of a melting end. The elementary glass filaments are subsequently drawn off via a rotating drum, with the filaments being split, by means of an evener and supported by air flow, into glass fibers having non-uniform staple lengths and conveyed into a device arranged in parallel with the drum axis for production of a fiber tape. Strength and close formation of the glass sliver herein are directly dependent on the drawing velocity. Customarily, textile processing aids (e.g. sizing agents) are furthermore added during the process of manufacturing the sliver material. Owing to the components contained in the glass, however, such glass slivers are not suited for applications at temperatures above 300-400° C.
Numerous trials have been undertaken to subject glass fibers to acid treatment in order to enhance their temperature stability, in order to remove glass constituents (boundary-forming substances) and partly remove network modifiers (GB 976 565, EP 236 735, GB 933 821, GB 20 94 363, U.S. Pat. No. 2,718, 461, U.S. Pat. No. 2,491,761, U.S. Pat. No. 4,778,499). In these known processes, acid treatment is carried out on the glass fibers in the sense of individual fibers (filaments), on glass fiber bodies such as mats, felts, loose bulk material etc., wherein the fibers are present randomly (at random orientations), or on particular textile follow-up products such as plain yarns or wovens on the basis of glass fiber filaments. Although it is possible to enhance the thermal strength of the fibers and products thus treated, the mechanical properties (fiber strength, elasticity etc.) thereof are, however, thereby reduced so strongly that processing into various textile follow-up products is not possible. The like materials are thus primarily utilised for manufacturing wovens having high specific gravities (cf. DE patent No. 42 40 354). For this reason it was attempted to ensure textile processing with the aid of additional process steps, by providing the acid-treated glass fibers with particular coatings (EP 236 735), or incorporating further materials such as organic textile fibers (DE-OS 42 21 001). These sophisticated measures to some extent improve the mechanical properties, however not the textile properties of these fiber materials. It has hitherto not been successful to obtain fiber materials having properties typical of cotton. Upon heating these known fibers, moreover, organic constituents are released which are partly hazardous to health. Manufacture of all previously known technical textiles for application temperatures above 400-500° C. cannot be implemented on the basis of these materials as the corresponding voluminous slivers are not available.
For a potential use in the high-temperature range about 1000° C. as textile fiber products, there have previously been furthermore proposed—apart from the named siliceous slivers and silica glass fibers, production of which starts out from a molten quartz material (temperatures in excess of 2,000° C.) and incurs enormous costs—plain yarns on filament basis (SiO
2
-contents in excess of 90%,). In order to render them more voluminous and bulky, these plain yarns are generally subjected to a sophisticated and costly processing stage, i.e. texturing. The texturing process is contrived such that the capillary glass filaments supplied to a nozzle by means of a feeding installation are intermingled by means of cold air (blast method). By this processing, however, it is equally not possible to obtain the desired bulky and voluminous fiber products having a highly textile character as in the present invention, which have substantially more points in common with a cotton fiber than with a fiber material presenting typical glass properties (fiber brittleness, skin irritation etc.). A possible variety of textile follow-up products obtainable from these textured plain yarns is thus a priori limited. Attempts to produce glass staple fiber yarns having a textured effect, which are disclosed in the prior art (DE-OS 195 05 618), do not constitute an alternative in this context because the utilised C glass sliver must in turn be processed with additional continuous filaments on the one hand and is not suited for use at elevated temperatures (400—approx. 1100° C.) on the other hand.
The inorganic fiber-based materials known in the prior art thus do not satisfy the following criteria:
highly textile fiber properties (cotton character, i.e., bulky, fleecy, voluminous structure, high air retaining capacity, similarity with a cotton flyer roving, pleasant sensation upon skin contact, absence of skin irritation, no brittleness of the fibers)
obtention or improvement of mechanical properties following an acid treatment
direct production of a variety of textile follow-up products; no limitation to technical textiles but use in textile industry moreover possible
no additional materials or measures (texturing, coating etc.) required for the manufacture of variegated textile follow-up products
sufficient thermal strength at continuous temperatures above 400° C.
no release of organic constituents during heating, no health hazards.
SUMMARY OF THE INVENTION
It is the object of the present invention to prepare an Al
2
O
3
-containing, high-temperature resistant glass sliver as a textile, high-performance fiber material which is suited to serve as a starting product for the manufacture of any textile follow-up products known up to the present. This textile high-performance fib
Robin Richter
Sven Lehr
Thomas Focke
Group Karl
Pendorf & Cutliff
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