| 摘要 |
409,274. Making window envelopes. GRAY, R. L., 55, 33rd Street, Brooklyn, New York, U.S.A. Sept. 24, 1932, No. 26591. Convention date, Sept. 25, 1931. [Class 94 (ii).] Window envelopes are formed from separate envelope blanks, the patch lying on one face of the blank and bearing the adhesive, preferably of a heat-plastic nature, pressure being then applied to unite blank and patch, to leave no loose edges to the patch to interfere with the insertion of the envelope contents. Transparent material 14, e.g. that known under the Registered Trade Mark " Cellophane " &c., from a roll A, is coated at 15 with gum, e.g. animal glue and glycerine, by the apparatus 10-13 and dried by passing through a chamber 16 of dry air at a low temperature. Feed rolls 25 lead it to cutters 26, the cut off patch being taken up by suction on a vertically reciprocating plunger 27. The envelope blank 18 is positioned on the table 17, and held thereon by suction, the window aperture overlying a depressed portion 24 of the table 17. The plunger 27 is provided with electric heating elements 34 to maintain its temperature at 135‹ F.-200‹ F. to render tacky the gum on the patch. The patch is affixed by the pressure of the plunger and is said to be " welded " into position, the blank with its patch being stated to be immediately available for any further operation. |
