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PatentsPATENT NUMBER
4,774,223
Abstract A diisopropylnaphthalene mixture containing 50% or more of 2,7-isomer is substantially odorless, has a low viscosity and exhibits a high dissolving power particularly for an electron-donating color former including a black color former. By coating of micro-capsules of an ink comprising the solvent and a color former on a substrate, a carbonless copying paper which is odorless and excellent in color developing speed including that at lower temperatures, can be obtained.
Chemicals Referenced "diisopropylnaphthalene isomers, containing 50 weight percent or more of the 2,7-isomer and an electron-donating color former, 3 to 20 parts by weight of the color former per 100 parts by weight of the solvent composition, the content of 2,7-isomer in the mixture of diisopropylnaphthalene isomers is 55 weight percent or more, 2,7-isomer in the mixture of diisopropylnaphthalene isomers is 70 weight percent or more, the total content of 1,4-, 1,5- and 1,6-isomers in the mixture of diisopropylnaphthalene isomers is 15 weight percent or less, the content of 2,6-isomer in the mixture of diisopropylnaphthalene isomers is 18 weight percent or less, 1,3-isomer in the mixture of diisopropylnaphthalene isomers is 7 weight percent or less, the content of 1,7-isomer in the mixture of diisopropylnaphthalene isomers is 7 weight percent or less, 1-dimethylphenyl-1-phenyl-methane as disclosed in U.S. Pat. No. 4,130,299 and 1-dimethylphenyl-1-phenylethane, etc., as disclosed in U.S. Pat. No. 3,936,566, etc., the common drawback of these solvents is strong odor possessed by the solvents per se, which makes the working environment during production of carbonless copying paper extremely bad and further gives extremely unpleasant feeling to the users of the carbonless copying papers during use thereof, although these solvents appear at a glance to be suitable as solvents for carbonless copying papers to be used as business forms, they do not satisfy the requirement of being substantially odorless, partially hydrogenated terphenyl disclosed in U.S. Pat. No. 3,968,301, solvents for carbonless copying paper which have been practically applied in the prior art, dialkylnaphthalenes disclosed in U.S. Pat. No. 3,806,463 and sec-butylbiphenyls disclosed in U.S. Pat. No. 4,287,074, also, U.S. Pat. No. 4,383,705 (Japanese Laid-Open patent application No. 116686/1982) propose to improve the color developing speed by mixing 1-isopropylphenyl-2-phenylethane with partially hydrogenated terphenyl, and/or diisopropylnaphthalene, DIPN is generally prepared according to (1) reaction between naphthalene and propylene, (2) reaction between naphthalene and an aromatic compound having a propyl group, or combination of these in the presence of a solid acid catalyst such as silica-alumina, zeolite, alumina, etc., and an acid catalyst such as aluminum chloride, etc., contains unaltered naphthalene, monoisopropylnaphthalene and polypropylnaphthalene such as tripropylnaphthalene or more-substituted product in addition to the desired DIPN (about 50% at maximum), the present solvent can be combined with a sec-butylbiphenyl solvent to improve its odor, the present solvent can be combined with a hydrogenated terphenyl to improve its color developing characteristic, the present solvent can be added to diarylalkanes such as 1,2-ditolylethane, 1,1-cumylphenylethane, the lower limit of dissolving power required may be practically 1%, preferably about 3% with CVL (crystal violet lactone, 20.degree. C.), including phenothiazine type lactone compounds such as benzoyl leuco-methylene blue, triphenylmethane, PSD-150 produced by Shinnisso Kako K.K., 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(4'-methylanilino)fluorane, 3-diethylamino-6-methyl-7-(2',4'-dimethylanilino)fluorane, 3-diethylamino-6-methyl-7-p-n-octylanilinofluorane, 2-di(.alpha.-phenylethyl)amino-6-diethylaminofluorane, 3-diethylamino-6-methyl-7-p-butylanilinofluorane, 2-p-dodecylanilino-3-methyl-1-diethylaminofluorane, 2-di-.alpha.-phenylethylamino-6-ethyl-p-toluylaminofluorane, etc., examples of the wall material may include polyamide resin, polyurethane resin, urea-formalin condensed resin, melamine-formalin condensed resin, gelatin, etc, condensed resins of p-alkyl-substituted phenols such as (p-phenylphenol, p-nonylphenol, p-octylphenol, etc.) with formalin, maleic acid-rosin resins, hydrolyzed styrene-maleic anhydride copolymers and ethylene-maleic anhydride copolymers, hydrolyzed vinyl methyl ether-maleic anhydride copolymers, carboxypolymethylene, or metal salts of hydroxybenzoic acid (particularly zinc salt), etc, 2,7-diisopropylnahthalene, butylbiphenyl mixture (Suresol 290, produced by KOCH chemical)"
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