United States Patent (19) (11) 4,055,704 Fahimian et al. (45) Oct. 25, 1977 TYPNG CORRECTION PAPER 3,813,441 5/1974 Miller-Schiedmayer et (54) al. ............... 260/567.6M (76) Inventors: John Fahimian; Clive H. Hare, both 3,922,240 11/1975 Berg et al. ............... 260/567.6 MX of 72 Second St., Cambridge, Mass. Primary Examiner-Charles E. Van Horn 02141 Assistant Examiner-Thomas Bokan (21) Appl. No.: 601,323 Attorney, Agent, or Firm-Richard P. Crowley Filed: Aug. 1, 1975 57 ABSTRACT 22 A correction sheet material for masking characters on a (51) Int. Cl’.......................... B32B 9/06; B32B5/30; substrate is composed of a carrier sheet and a thin dry B32B 9/04 coating layer on the carrier sheet, the coating layer (52) U.S.C. ...................................... 428/411; 106/27; adapted, on the application of sufficient pressure, to be 106/296; 106/300; 106/306; 106/308 F; transferred from the carrier sheet onto the characters on 106/308 N; 156/234; 156/326; 197/172; the substrate, the coating layer comprising a pigment in 197/181; 260/567.6 M; 427/146; 427/147; an amount to provide sufficient opacity to cover the 427/153; 428/537; 428/539; 428/914 characters to be masked, and a high molecular weight (58) Field of Search ............... 428/914, 537, 539, 411, organic ammonium salt as a binder for the pigment, and 428/913; 427/146, 147, 153; 252/316; as an adhesive agent for the subsequently transferred 260/567.6 M; 197/172, 181; 156/234, 326; coating, the salt insoluble in water and also in oils used 106/27, 266,308 F, 308 N in typewriter ink and carbon paper, the salt present in the coating layer in both continuous film and precipi (56) References Cited tated salt form and on the application of pressure, a U.S. PATENT DOCUMENTS strong opaque film of pigment and precipitated salt 3,114,447 12/1963 Wollowitz............................. 197/172 particles is transferred to mask the character on the substrate. 3,459,127 8/1969 Barouh........ pse 197/181 X 3,515,572 6/1970 Dabisch ...... is as 428/914 X 3,776,864 12/1973 Woerner........................... 428/94X 11 Claims, No Drawings 4,055,704 1. 2 tated particles. This property occurs because of the unique combination of a high molecular weight and TYPING CORRECTION PAPER highly ionic character of the organic ammonium salts BACKGROUND OF THE INVENTION: used in our invention. The combined effect of these two Transfer sheets, such as typing correction paper, car 5 properties strongly influences solubility in such solvents bon paper, decalcomania sheets and the like, typically as petroleum naphthas and alcohols and the degree to comprise a thin opaque coating layer on a carrier sheet, which they precipitate from a solution in these solvents. such as fabric, paper or a deformable plastic sheet like Thus when a suitable organic salt is made to dissolve polyethylene. The coating layer is subject to transfer to completely in aheated solvent to which a pigment, such another surface by the application of a certain pressure 10 as titanium dioxide, is added, a large fraction of the salt level, such as the pressure exerted by a typewriter key, will precipitate out as discrete particles when the mix but is immune to transfer by light pressure, such as by ture is ultimately cooled. A small fraction of the salt will ordinary handling or use. In effect, such transfer sheets remain dissolved even in the cold mixture. If this mix permit the physical movement of a portion of the dry ture is then coated in a thin layer onto a substrate, such coating layer to another surface on the application of 15 as paper, the precipitated salt and the pigment will de pressure which is sufficient to rupture the adhesive posit as discrete particles. The remaining salt, being bond of the coating layer to the carrier sheet, and which completely dissolved in the solvent system, forms a increases the adhesive bond in the dry coating layer. lightly cohesive film as the solvent evaporates, which Depending on the particular use, the coating layer may loosely binds both pigment and precipitated salt to be the same or a different color or shade than the sur 20 gether and to the substrate; for example, in a weight face to which the layer is to be transferred. In correc ratio of film to precipitate salt of about 0.01 to 0.40. In tion paper, the coating layer more commonly is de this form as a dry coating, the product is ready for use signed to match the paper to be corrected so that erro as a transfer sheet material. neously typed characters may be effectively masked by The organic ammonium salts useful in our invention the use of the correction paper. 25 comprise those salts which have a sufficiently high Pressure-sensitive transfer sheets, particularly correc molecular weight to have a melting point above normal tion paper as presently commercially marketed, typi storage temperatures; for example, above about 130 F, cally comprise a carrier sheet with a coating composi and which at least are partially soluble in the selected tion composed of a pigment like titanium dioxide to solvent system employed to form the coating layer. provide opacity, a transferable binder composed of 30 Such salts comprise the cationic surface-active acyclic metallic soaps, waxes, resin and/or oils, and an adhesive organic ammonium salts having one, two, three or four agent to affix or adhere the binder and pigment lightly hydrocarbon-saturated or unsaturated substituent to the carrier sheet prior to cohesion and transfer of the groups, particularly the mono and dialkyl and fatty coating layer on the application of pressure. Typical acid long-chain hydrocarbon salts. The remaining sub transfer sheet materials and the coating compositions 35 stituent groups may be hydrogen or lower alkyl groups; employed are described in U.S. Pat. Nos. 2,931,752; e.g., C1-C, such as methyl. In particular, the ammo 3,025, 180; 3,515,572; 3,552,990; and 3,776,756. Our in nium salts useful in our coatings should have one or vention relates to the field of transfer sheets and im more organic groups of at least 18 carbon atoms; e.g., proved transfer sheets, particularly typing correction from about 18 to 22 carbon atoms or a mixture thereof. papers and to methods of preparing such materials. 40 Also useful is a mixture containing ammonium salts SUMMARY OF THE INVENTION with one or more organic groups of 16 and fewer car bon atoms and ammonium salts, with one or more or Our invention relates to transfer sheet materials, par ganic groups of 18 to 22 carbon atoms. In the preferred ticularly correction sheet materials and to methods of embodiment, the ammonium salts comprise mono or di preparing and using such materials. In particular, our 45 Cis-C saturated or unsaturated long-chain hydrocar invention concerns a correction sheet with an improved bon groups and mono or dihydrogen atoms or methyl and novel coating layer on the carrier sheet. groups. When only ammonium salts containing organic Our transfer sheet materials comprise a carrier sheet groups of 16 and fewer carbon atoms are used, we have or substrate and a thin coating layer thereon which is found that the correction sheets are unsatisfactory, pressure-sensitive, and which layer comprises an 50 since bleedthrough of the typewriter ink often occurs opaque particulate material, such as a pigment, and an due to the higher solubility of salts containing such ammonium salt. We have found that the use of metallic groups. organic materials or other prior art binders in transfer The high molecular weight organic acyclic ammo sheets and the disadvantages associated therewith may nium salts useful in our coatings are represented by the be avoided by the use in particular organic ammonium 55 formula: salt compounds. Further, we have discovered that a certain class of organic ammonium salts of our inven tion may be employed as combination binder and adhe sive agents in transfer sheet layers. Our organic ammo nium salts also function as wetting agents for the pig ment used to opacify the coating layer and permit excel lent dispersion of the pigments in the preparation of the coating mixture. In our invention, a single ammonium salt can function wherein R is a cationic organic radical or hydrogen as both the binder and adhesive, since it can coexist in 65 atoms with at least one R being a cationic organic radi two different physical states within a transferable coat cal, and A is an anionic radical as herein set forth. ing layer. It can exist as a continuous film. Also, it can Where all the Rs are organic radicals, the salt is referred exist in the form of microscopic-sized discrete, precipi to as a quaternary ammonium salt, and otherwise the 4,055,704 3 4. ammonium salts are sometimes referred to as amine. acetone and other solvents typically used in preparing salts. The amine salts are formed by the reaction of a such coatings, such as those solvents set forth in the primary, secondary or tertiary amine with an acid. For cited prior art patents. the purpose of this application, the term "ammonium The carrier sheets on which the thin dry coating layer salt' shall be used to define such quaternary and amine containing the salts and pigment combination of our salts where the nitrogen atom contains four radicals invention are prepared include any substrate sheet ma bonded thereto. terial, but typically for correction sheet materials com The organic cationic radicals include, but are not prise a thin sheet material of paper, fabric or of a poly limited to; the arichidyl-behenate, stearate, oleate, lino mer like polyethylene to which the dry coating layer is leate, tallow and other fatty acid C18-C22 groups and 10 loosely adhered, and which, when struck on the oppo mixtures thereof.