Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Patent
1997-03-07
1999-06-01
Mosley, Terressa
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C08G 6400
Patent
active
059089164
DESCRIPTION:
BRIEF SUMMARY
The present invention is in the field of optical polymers, more particularly, optical polycarbonates for use in optical components. In the field of optical polymers polycarbonates are preferred in view of their low light absorbance in the wavelength area for optical uses (1300-1600 nm), making it possible to obtain optical components with low light loss.
Polymeric optical components usually have a multilayer polymer structure one a substrate with a guiding layer (the core clayer) sandwiched between two polymer layers of a lower refractive index (cladding layers). Said layer structure can be formed conveniently by applying the various subsequent layers in the form of a solution, e.g., by means of spincoating, followed by evaporation of the solvent. However, in spincoating layer-on-layer it was found that the first polycarbonate layer re-dissolves when the next layer is applied onto it. As it is essential for optical components to have a specific layer structure with each layer having a specific refractive index and layer thickness, this re-dissolving of the layers is a serious problem: since no well-defined refractive index contrast and specific layer thicknesses can be obtained, the light travelling through the component is not confined within the core layer, resulting in substantial light losses.
In EP-A1-0 645 413 NLO polycarbonates are described. In order to solve the layer-on-layer spincoating problem, it is suggested here to introduce polyisocyanates or polyepoxides into the polycarbonate as cross-linkers. However, it proved quite hard to make a polycarbonate cross-linkable without detrimentally influencing the properties which determine the applicability of optical polycarbonates in optical components, such as Tg, refractive index, light loss, etc. For instance, it was found that the use of Desmodur N.RTM., a polyisocyanate, posed problems due to swelling of the layers. Furthermore, it was found that even after curing the polycarbonate was still partly soluble in the spincoating solvent. Also, the use of polyepoxides was not optimal: it was found that the layers could not be reproducibly obtained: some of the layers were sound but others appeared to have cracks.
The present invention provides a cross-linkable or cross-linked optical polycarbonate wherein the properties determining the applicability in optical components are detrimentally affected hardly if at all, and the layers can be applied on top of each other without re-dissolving of the first layer.
For this reason the cross-linkable or cross-linked optical polycarbonate according to the invention is obtained from a monomer mixture comprising: ##STR2## wherein: P stands for --Cl, O--R, an imidazole group or --O--Ph, Q stands for --Cl, O--R, an imidazole group or --O--Ph, --Ph--Ph--, halogenated --Ph--Ph, --Ph--C(CH.sub.3).sub.2 --Ph--, --Ph--SO.sub.2 --Ph--,--Ph--C(CF.sub.3).sub.2 --Ph--, halogenated --Ph--C(CH.sub.3).sub.2 --Ph, halogenated --Ph--C(CF.sub.3).sub.2 --Ph, phenolphthalein, --Ph--C(Ph).sub.2 --Ph,
With the use of 2,3 dihydroxy propyl methacrylate as a cross-linker, polymerisation can take place separately from curing (cross-linking). The polymerisation reaction of the polycarbonates can take place at approximately room temperature, while the curing reaction is performed either thermally (50 to 220.degree. C., depending on the initiator used) or via photocuring with irradiation (UV or visible light).
The optical polycarbonate according to the invention can be applied in a conventional way, for instance by spincoating. After (or during) evaporation of the spincoating solvent, the layer can be cured, so that the next layer can be applied without any problem.
For thermal curing radical initiators, for instance, peroxides such as dicumyl peroxide, ditert. butyl peroxide, dilauroyl peroxide and dibenzoyl peroxide, azobisisobutyronitrile (AIBN) etcetera, can be included in the spincoating solution. Suitable photoinitiators are for instance Irgacures .RTM., ex Ciba Geigy and Darocures .RTM., Ex Merck. The initiators are usually present in
REFERENCES:
patent: 3124554 (1964-03-01), Schnell et al.
patent: 5142605 (1992-08-01), Diemeer et al.
patent: 5208299 (1993-05-01), Bales et al.
"Polycarbonates", Kirk-Othmer Encyclopedia of Chemical Technology, Third Edition, vol. 18, pp. 491-492 (1982).
"Polycarbonates", Encyclopedia of Polymer Science and Engineering, vol. 11, pp. 680-687 (1982).
Boonstra Tjerk Oedse
van Olden David
Woudenberg Richard Herman
Akzo Nobel N.V.
Fennelly Richard P.
Mosley Terressa
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