Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
2002-01-29
2004-11-09
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C428S441000, C428S430000, C428S412000, C428S415000, C427S165000, C427S166000, C427S168000, C427S169000, C427S553000, C065S066000, C065S090000
Reexamination Certificate
active
06815070
ABSTRACT:
The invention relates to a glass-plastic composite film, especially for use in electronic components and devices, such as displays, consisting of a glass film which is between 10 &mgr;m and 500 &mgr;m thick, and a polymer layer with a thickness between 1 &mgr;m and 200 &mgr;m applied to at least one of its side faces. Furthermore, it relates to methods for manufacturing said glass-plastic composite film and using the same.
Flat glass substrates are a suitable substrate material for many applications where transparence, high chemical and thermal resistance and defined chemical and physical properties are important. In particular, these are the areas of application where the methods for thin film and thick film technology are used, such as displays, thin and thick film sensors, solar cells, micro-mechanical components and lithographic masks. In recent times, the demand for new product functionalities and areas of applications has called for ever thinner and ultra-thin substrates that have the known good properties of glass substrates, but also have new properties, in part, such as flexibility. Again, the typical fields of application are electronic applications, such as sensors and membrane elements.
Especially in displays, for example liquid crystal displays (LCD), the trend is increasingly moving toward a more appealing design and therefore new functionalities are required. In particular, these are ultra-thin and especially light displays, for example for portable pocket devices, flexible displays for devices with a rounded housing form, such as cell phones or round pin-type devices or displays for smart cards or shelf price tags or displays that are based on organic or inorganic light emitting layers, the so-called light emitting organic polymer displays (OLED).
Generally, this type of display is structured as follows: The core is a cell that houses the liquid crystals or the polymers. It is provided with a front and a rear plate on which electrodes are applied. In most liquid crystal displays the front and rear walls of the cell are both joined by a polarizer. In reflective displays, a reflector plate is provided behind the rear polarizer. In the case of the emitting polymers the counterelectrodes can also be vapor-deposited directly to the polymer before the display is sealed with the rear plate. In order for the display to function as well as possible it must be ensured, for example, that the liquid crystals are able to align as evenly as possible and that the electrode pairs all have the same distance from each other, if possible, as otherwise distortions or localized intensity fluctuations will occur in the display. One influencing factor is the surface quality of the substrates used for manufacturing the individual components.
Preferred substrate materials for manufacturing the individual components are glass and plastic. The special advantages of glass are that it is chemically and photo-chemically inert, optically isotropic, temperature-resistant, mechanically stable and it also has a hard surface. However, it has a relatively high density, it is brittle and thus highly susceptible to breaking. Breaking glass in the production process not only causes losses for the manufacturer because of high waste, but also because of the fact that the process has to be stopped every time so as to remove all splinters from the machines.
Plastics have a lower density and they are elastic and resistant to breaking, but they also have various disadvantages: In the past few years, substrate materials have been developed and manufactured on the basis of high quality plastic films for manufacturing displays as a replacement for thin glass substrates. All these films require complex special manufacturing processes so as to achieve the required properties. Such complex manufacturing processes make the substrates considerably more expensive. It was also found that in spite of considerable development efforts the water and vapor permeability of such substrate films cannot be adequately reduced. The consequences are that the quality and the lifetime of the LCDs made of such substrate films are highly limited. In the so-called OLEDs the oxygen diffusing through the film will result in oxidizing the organic semiconductor layers and the electrodes consisting of base metals and thus it will also reduce the lifetime of the displays. When plastic is used as a protective layer for the display the susceptibility to scratches will reduce the lifetime.
Similar to the safety glass industry, attempts are being made to combine the favorable properties of glass with the good properties of plastic: In DE-OS 36 15 277 A1, glass panes are coated with plastic by means of melting on so as to provide protection against splintering. DE-OS 31 27 721 A1 specifies plastic sheets which are coated with glass films as scratch protection where the coating takes place under the effects of pressure and/or heat, but preferably using an intermediate inserted hot-melt adhesive film.
Analogous, several examples are known in the field of display technology where the properties of glass and plastic are combined. An approach of providing glass with a protective plastic layer is known from the Korean disclosure of patent KR-A 98-3695. In all probability, the glass is brought to the desired thickness by means of etching and the protective plastic layer then has to close the pores caused by the etching and also serve as protection against breaking.
The break protecting function primarily consists of preventing the propagation of micro-cracks that already exist. Except for saying that it is a resin from the group of thermosetting plastics the selection of the polymer is not discussed in more detail. Also, it is not disclosed in detail how the protective coat is applied. Assuming a commonly used glass thickness for producing displays at the time of the patent application, which typically was between 0.55 mm and 1.1 mm at that time, and the etched glass surface the glass-plastic composite materials produced thus will not meet the current requirements for display applications.
With regard to the production of polarizer films, DE-OS 196 06 386 A1 describes an oriented optically active dye film of plastic which is applied for mechanical stabilization to a glass film by means of pressing, melting, preferably adhesion. The adhesive agent provides additional mechanical stabilization for the dye film. The thickness of the glass film ranges between 10 and 200 &mgr;m, the thickness of the dye film is between 5 and 60 &mgr;m.
Applying the dye film is not without problems. With pressing, the scrap as a result of breaking glass is very high; melting is a complex process which can have an adverse effect on the properties of the dye film; adhesion has the following disadvantages: The process of bonding films, in this case a polymer film with a glass film, is also called laminating. Lamination generally takes place in that pressure is applied by means of rollers. This causes considerable stress on the glass film, which, especially with very thin films, results in breaking or damaging the glass film, for example scratching the surface.
At least four separate manufacturing processes are required: manufacturing the thin glass, manufacturing the film, coating with adhesive and the actual laminating process, which results in significant costs. Also, the adhesion and laminating methods have to meet high requirements because the product, especially for display applications, must not contain any air or dust particles. For the selection of the adhesive agents it should be taken into consideration that they generally have a limited temperature and solvent resistance. A homogeneous thickness of the glass laminate cannot be adequately ensured because of fluctuations in the thickness of the ductile adhesive layer.
The use of polymer films in itself is problematic because when the temperature fluctuates they build up considerable pressure and tensile stresses in the laminate because of their high degree of cross-linking. The thermal coefficients of expansion of p
Bürkle Roland
Deutschbein Silke
Mauch Reiner
Sossenheimer Karl-Heinz
Weber Andreas
Baker & Daniels
Blackwell-Rudasill G.
Jones Deborah
Schott Spezialglas GmbH
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