INK COMPOSITION FOR HIGH-SPEED SCREEN PRINTING, PRINTED MATTER PRODUCED BY THE HIGH-SPEED SCREEN PRINTING OF THE INK COMPOSITION, AND METHOD FOR PRODUCING THE PRINTED MATTER

摘要

[Problem]In recent year s, high-speed screen printing using cylinderpresses is being carried out with a greater variety of designsfor printed matter, not only for graphics decoration but alsofor high-speed screen printing onto electric and electronic parts,as well as increasing high definition of printed images, and demandis increasing for more convenient and lower cost and more rapidproduction of printed matter comprising both fine patterns andwide-area solid patterns . Also desired is higher quality andhigher definition of the visibility of printed images that compriseboth fine patterns and solid patterns, by improving the sharpnessof the image edge sections in solid patterns while also obtaininga satisfactory leveling property.[ Solution Means]An ink composition for high-speed screen printing, whichis an ink composition for high quality/high definition high-speedscreen printing that, when producing printed matter by high-speedscreen printing onto an object to be printed using a screen printingplate made by flat working a photosensitive emulsion film on a355 mesh/inch polyester mesh printing plate, at a squeegee speedof 400 mm/sec, produces printed matter with a printed image edgespreading width of no more than 10 µm from the printed image designdimensions of the printing plate, the ink composition forhigh-speed screen printing containing a solvent with a boilingpoint of not less than 170°C at not less than 70 wt% of the totalsolvent, and a prepolymer or polymer with a weight-average-molecularweight of not less than 2000 at not ess than 7 wt%with respect to the total ink composition, and having a viscosityof not less than 6 Pa.cndot.s and less than 30 Pa.cndot.s as measured witha BH-type rotating viscosimeter at 25°C, and a thixotropic index(TI value) of 2.0 to 8.0, the measured flow radius value of 14.0to 24.0 mm after 1 minute from the start of measurement by a flowproperty measuring method using a spread meter at 25°C accordingto JIS K5701-1:2000.