Patent GB-792840-A (GB)
Title: Improvements in or relating to fluorescent screens
IPC: H01J29/18
Filed: 1954-07-05
Abstract: A process for producing a dot or line-fluorescent screen for a C.R.T. comprises coating a support with a layer of a composition containing an addition photo-polymerizable ethylenically unsaturated compound, finely-divided phosphor particles and an initiator for addition polymerization activatable by actinic light, exposing the composition to actinic light through an opaque mask having a plurality of small light apertures or transparent areas, and developing the phosphor-polymer image by removing the layer in the non-exposed areas by the application of a solvent. The polymerizable compound is preferably a monomer, particularly monoethylenically unsaturated monomers wherein the unsaturation is terminal, i.e. monomers having the characteristic formula: <FORM:0792840/IV (a)/1> where R is hydrogen, an alkyl radical or a halogen, and X is a hydrocarbon radical or a negative group, e.g. a halogen, -CN, -COOH, -COOR1, -CHO, -OCOR and ether radicals, -CONH2, -CONHR1, -CONR12, -COR1, e.g. -OR11, where R and R1 are alkyl radicals and R11 is an alkyl or aryl radical.  From 5-100 per cent of the monomers may be cross-linking, e.g. those containing two ethylenic unsaturations, preferably terminal, conjugated or not, such as methacrylic and acrylic acid diesters of ethylene glycol and the polyethylene glycols or mixtures of these alcohols or of the polymethylene glycols, or divinylacetylene, divinylbenzene, di-isopropenyldiphenyl, crotyl methacrylate, diallyl phthalate, diallyl maleate and triallyl cyanurate.  Other suitable polymers are described in U.S.A. Specification 2,255,313, made by reacting an ethylene-a ,b -dicarboxylic acid or anhydride with a glycol. Specific polymerizable materials include a mixture of vinyl chloride and allyl glycidyl ether, a mixture of methyl methacrylate, polymethyl methacrylate and the monomeric dimethacrylate esters of polyethylene glycol of molecular weight about 200 described in U.S.A.  Specification 2,468,094, a methyl methacrylate/polyethylene glycol dimethacrylate mixture, a mixture of monomeric polyethylene glycol dimethacrylate and acrylonitrile, and a mixture of poly-(methyl methacrylate co-isobutyl methacrylate) and polyethylene glycol dimethacrylate. Initiators referred to include vicinal ketaldonyl compounds such as diacetyl and benzil, g -ketaldonyl alcohols such as benzoin and pivalvin, acryloin ethers such as benzoin methyl or ethyl ethers, alpha-hydrocarbon substituted aromatic acyloins including a -methylbenzoin, a -allylbenzoin and a -phenylbenzoin. Particular polymerizable compositions referred contain a mixture of styrene and polypropylene glycol phthalate maleate or triethylene glycol dimethacrylate, with benzoin methyl ether as initiator.  The layer composition can also contain preformed compatible condensation or addition polymers, or inorganic fillers, e.g. ground glass, glass fibres and barytes particles. Solvents for removing the unpolymerized areas of the screen include isopropyl acetate, and mixtures of methanol or ethanol with methyl, ethyl or propyl acetate. Specifications 702,468 and 713,908 [both in Group XL(a)] are referred to.