Stock material or miscellaneous articles – Composite – Of polycarbonate
Patent
1996-05-16
2000-07-11
Nakarani, D. S.
Stock material or miscellaneous articles
Composite
Of polycarbonate
156242, 156246, 1563082, 1563096, 349119, 428 16, 428480, B32B 2708, B32B 2736
Patent
active
060870079
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an optically transparent and heat-resistant plastic laminated sheet, its producing method and a heat-resistant transparent substrate using the aforementioned laminated sheet.
BACKGROUND ART
With rapid progress of the electronic techniques lately, the field of photoelectronics such as liquid crystal display elements, electroluminescent display elements and photoelectronic transfer elements for solar cells has been spreading steadily.
In such fields, photoelectronic elements have been supplied to various uses generally for such elements placed on a glass substrate having a transparent conductive layer.
Since, however, glass is problematic due to its insufficient mechanical strength, especially brittleness, this resulting in lowering of durability of elements and, to cope with it, substrates specially treated like those of tempered glass are now being often used. When such elements are incorporated into portable devices in particular, their weight is increased due to the large specific gravity of glass. Therefore, thinning of the glass substrate is required and substrates 0.4 mm or so in thickness are now feasible. However, its brittleness still remains and problems such as lowering the yield due to breaking in the process or lowering of impact strength of the elements remain unsolved.
Thus, strengthening and weight-saving of substrates are strongly desired and from the viewpoints of lightness, impact strength and interchangeability with glass, generally preferred are optically transparent (i.e. 80% or more in ray transmission and 5% or less in haze) plastic substrates having 0.2-0.5 mm thickness and having a reasonable rigidity.
With respect to the process temperature required for the formation of photoelectronic elements taken into consideration, however, a high heat resistance of not less than 180.degree. C., preferably not less than 200.degree. C. are required and, when application to liquid crystal elements is considered, a low retardation preferably of not more than 50 nm, more preferably, not more than 20 nm, is required. Meanwhile, when a plastic film or sheet is made, its molecules are subjected to orientation, and it is particularly difficult to obtain a film or sheet which is low in retardation by a melting method, especially when the material used is high in heat resistance. For example, when a material used is relatively low in heat resistance such as polycarbonates, it is even possible to obtain a sheet low in retardation of not more than 50 nm which is usable for the production of liquid crystal display elements, but no low-retardation sheet is obtainable from a material of not less than 180.degree. C. in glass transition temperature such as polyarylates.
Meanwhile, in the case of supernematic liquid crystal displays (STN-LCD), it is a general practice to use a high molecular film (phase difference film) with its retardation, which is represented by the product of birefringence and thickness, controlled to a specific value stuck to a glass substrate in order to improve its display quality. When the substrate is made of a plastic, features not obtained with a glass substrate such as imparting the phase difference function thereto for cost saving are expected. Thus, particularly desired is a plastic substrate which is heat-resistant with its retardation well controlled to be not less than 100 nm, preferably in a range of about 100-700 nm.
For that purpose, proposed is a method of using heat-resistant high molecular materials such as polyarylates, polysulfones, polyethersulfones, and polyetheretherketones made in film form by a solvent casting method and used in the form of the so-called plastic liquid crystal cells etc. (Japanese Laid-open Patent Publication No. 119321/'84, Japanese Laid-open Patent Publication No. 167208/'85, Japanese Laid-open Patent Publication No. 147721/'85, Japanese Patent Publication No. 41539/'86, U.S. Pat. No. 4,623,710), but such plastic substrates are filmy some 0.1 mm in thickness. These are, however, more flexible
REFERENCES:
patent: 5227458 (1993-07-01), Freitag et al.
Kenichi et al., "Heat Resistant, Transparent and Multilayer Plastic Sheet", Patent Abstracts of Japan, vol. 15, No. 253, (M1129) and JP Publication No. 03082530 published Apr. 8, 1991, Abstract.
WPI, Section Ch, Week 8705, "Mat Films for Keyboards, Displays, Tracking Films, etc.", Derwent Publications Ltd., London, GB, Class A23, Appl. No. 87-032203, Publ. No. JP61287741A on Dec. 18, 1986, Abstract.
Hitoshi et al., WPI, Section CH, Week 9151, "Electrode Substrate for Liquid Crystal Display Panel," Derwent Publications Ltd., London, GB, Class A28, Appl. No. 91-374148, Publ. No. JP3252625A on Nov. 11, 1991, Abstract and Drawing.
WPI, Section Ch, Week 8541, "Transparent Electroconductive Film," Derwent Publications Ltd., London, GB, Class A28, Appl. No. 85-252815, Publ. No. JP60167208 on Aug. 30, 1985, Abstract.
Fujii Sadao
Matsumoto Kenji
Kanegafuchi Kagaku Kogyo & Kabushiki Kaisha
Nakarani D. S.
LandOfFree
Heat-Resistant optical plastic laminated sheet and its producing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heat-Resistant optical plastic laminated sheet and its producing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat-Resistant optical plastic laminated sheet and its producing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-540082