US3300879A - Mark resistant coating - Google Patents

Description

Jan. 31, 1967 L. T. COPPETA 3,300,879

' MARK RESISTANT COATING Filed March 30, 1965 TRUE FALSE 1 Tn c: \l\ lf |1:\. nu l. U 4

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LEONARD T. COPPETA ATTORNEYS 3,300,879 MARK RESISTANT CGATING Leonard Thomas Coppeta, North Andover, Mass., as-

signor to The Carters Ink Company, Cambridge, Mass, I

a corporation of Massachusetts Filed Mar. 30, 1965, Ser. No. 443,979 1 Claim. (Cl. 3548) This invention relates to self-correcting testing devices, more particularly to a sheet for receiving test marks in a manner which indicates whether a given marking is correct.

The testing devices of this invention may be used in connection with numerous teaching programs which can utilize testing of the multichoice type. In these the student is given a question, or instructions requiring him to mark a score sheet in one 'or several areas according to the particular test pattern. Certain areas correspond to right answers, and others to wrong answers. The test is scored by tallying the number of right and wrong answers.

In the testing device of this invention the score sheet is designed to receive markings only in selected areas, which may correspond to either the right answer or the wrong answer, and the student is immediately apprised of whether his selection of a particular marking area is correct.

The score sheet of this invention is provided with visible marks defining the areas to be marked, the surfaces of a selected number of which are of sufiicient roughness and high coefiicient of friction to receive a mark from a given pencil or similar marking device, and the surfaces of the others are of sufiicient smoothness and low coefiicient of friction as not to pick up a mark from the same device.

It has been found that selected surface areas of a sheet may be rendered relatively less capable of being marked upon without substantially altering the appearance or feel of the surface sufliciently to designate to a casual observer which area is which. Preferably the base sheet will be paper having a smooth surface, such as a bond paper or other rag pulp or chemical wood pulp paper, which may be uncoated or surface sized.

Selective areas of the paper are rendered more mark resist-ant by the application of a coating of plastic, polymeric, or waxy material having surface properties that render it incapable of eliciting a mark from a soft lead pencil or similar device.

Many materials and formulations may be devised to behave in this manner, examples of which are given below. In general, the coating will make use of such materials as waxes, e.g., paraflinic hydrocarbon waxes, polyethylene, aluminum stearate, halogen substituted polyo-lefins, high molecular weight alcohols and esters, and other similar solid materials of a soft and waxy or unctuous nature capable of forming a coating having a smooth surface. In addition, various compatible modifiers, plasticizers and additives, commonly employed in materials of this nature may be incorporated.

By way .of example the following coating compositions may be employed with entirely satisfactory results, the first of these being the presently preferred embodiment.

3,300,879 Patented Jan. 31, 1967 "ice Example I Percent by Ingredient: weight Nuosperse 657 1.0 5 EHEC-High 3.0 Piccotex 120 Resin 7.0 Aluminum stearate 12.0 Isop-arK 43.0 Chlorothene NU 15.0 Methyl ethyl ketone 15.0 A-C Polyethylene 656 4.0

A solution of EHEC and Piccotex 120 in methyl ethyl ketone and Chlorothene is prepared and set aside. Onetwelfth (1.0% of total formulation) of the aluminum stearate and the A-C Polyethylene 656 is dissolved in Isopar K at 160 F. This solution is allowed to cool to room temperature, whereupon the polyethylene forms a dispersion, and the remainder of the aluminum stearate is added with agitation. Finally, the solution of EHEC This formulation is processed in the same manner as in Example I. The EHEC and Piccotex are dissolved in the Chlorothene, and the Microthene and A-C Polyethylene 656 are dispersed in the Isopar.

Example III Percent by Ingredient: weight EHEC-High 2.0 Piccotex 120 Resin 15.0 Isop ar K 30.0 Chlorothene 30.0 Nuosperse 657 a- 1.0 Stearic acid 2.0 Zinc stearate 5.0

Microthene 200 12.0 A-C Polyethylene 656 3.0

This formulation is processed in the same manner as in Example I. The EHEC and Piccotex are dissolved in the Chlorothene, and the Microthene and A-C Polyethylene 656 are dispersed in the Isopar. Zinc stearate and stearic acid are used in lieu of aluminum stearate.

Example IV Percent by Ingredient: weight A-C Polyethylene 656 40 Tergitol NPX 10 Potassium hydroxide .6 Water 49.4

The ingredients are combined and mixed together. In the foregoing examples:

Nuosperse 657 is a combination wetting, dispersing, and anti-settling agent produced by the Nuodex Products Division of Hey-den Newport Chemical Corporation.

EHEC-High is a high viscosity125 to 250 centipoises-ethyl hydroxy ethyl cellulose, manufactured by Hercules Powder Company.

Piccotex 120 is an aromatic, thermoplastic styrene copolymer resin, having a softening point, ball-and-ring, of 120 C., produced by Pennsylvania Industrial Chemical Corporation.

I-sopar K is a synthetic petroleum hydrocarbon having a chemical composition that is about 95 percent isoparaflinic (branched), sold by the Humble Oil & Refining Company.

Chlorothene NU is a specially inhibited 1,1,1-trichloroethane, prepared by The Dow Chemical Company.

The A-C Polyethylene is an oxidized, emulsifiable polyethylene produced by Allied Chemical Corporation.

Microthene 200 is a polyethylene powder produced by US. Industrial Chemicals Company.

Tergitol NPX is a nonyl phenyl polyethylene glycol containing 10.5 moles of ethylene oxide, an all-purpose non-ionic detergent and wetting agent produced by Union Carbide Chemicals Company.

A testing device embodying this invention is shown in the accompanying drawing in which FIG. 1 is a plan view.

The sheet 2, preferably formed of bond paper of 16-28 lbs. per ream (500 sheets 17" x 2 is imprinted with test questions which call for answers to be applied by marking one or another of several areas 4. Certain of these, 6, are provided with a substantially invisible coating of a mark resistant composition, such as that described in Example I above. Preferably the material is applied to a thickness of dour-tenths of a mil or more, conveniently by silk screening the coating composition onto the paper and then allowing it to dry.

In use the coated areas will resist a mark from a soft lead pencil such as that designated Dixon, Andel black 1995.

Other suitable paper bases include white offset book paper, typically weighing -100 lbs. per ream (500 sheets 25 x 38), text paper, or ledger paper, which may be of rag or chemical wood pulp. These papers have a surface appearance similar to that of the coating, and render the coated areas unobvious to casual observation. Calendered or clay coated papers on the other hand have a surface index of reflection which so differs from the coating that the coated areas can be seen.

Although this invention has been described with specific reference to its preferred embodiments, it is contemplated that modifications will occur to those skilled in the art and familiar with the principles herein set forth, and that such may be made without departing from the scope of this invention.

Having thus disclosed my invention and described in detail a preferred embodiment thereof, I claim and desire to secure by Letters Patent:

A self correcting testing device designed to receive marks from a pencil in selected areas corresponding to a predetermined test pattern comprising a score sheet having visible marks defining areas including said selected areas and also other areas outside of said test pattern, the surface of said selected areas of said sheet being of sufficient roughness and high frictional coefiicient to receive a mark from a given pencil, and the surfaces of said other areas being coated with a substance of sufiicient smoothness and low frictional coefficient to resist marking from said pencil.

References Cited by the Examiner UNITED STATES PATENTS 1,849,708 3/1932 Colbert et al. 3566 1,883,775 10/1932 Finkenbinder 35-48.1 1,884,197 10/1932 Peterson et al. 35-2-6 2,210,879 8/ 1940 Cahoon et al. 3526 2,618,866 11/1952 Adams 3548.1

EUGENE R. CAPOZIO, Primary Examiner.

S. M. BENDER, R. W. WEIG, Assistant Examiners.

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