US2862832A - Heat transfer - Google Patents

Description

Dec. 2, 1958 R. G. SHEPHERD, JR 2,862,832

HEAT TRANSFER Filed Jan. 9, 1956 jizz eiwor United States Patent HEAT TRANSFER Application January 9, 1956, Serial No. 558,129

6 Claims. (Cl. 117 3.2)

The present invention relates to heat transfers and particularly to improvements in heat transfers embodying a wax release coating.

The objects of the present invention. are to provide an improved heat transfer. embodying a wax release layer, to provide an inexpensive heat transfer receptive to high quality printing, to provide a heat transfer which can be readily printed on conventional equipment and with conventional inks, and to provide a heat transfer which can be transferred to impermeable as well as permeable surfaces without the need for special adhesive layers over the printed design and without need for sizings on the paper carrier.

Heat transfer products embodying release coatings of wax have long been known but the products heretofore disclosed have possessed severe limitations which have prevented their wide-spread use. One limitation has been the difficulty in printing due to ink striking into the wax during printing, ink migration into the wax after printing, ink crawling on the wax surface, wax oifset during storage, and picking and embossing of the wax during printing.

A further limitation in prior wax transfers has been the faulty transfer of the design, particularly where the surface to be labeled is smooth and impermeable. This faulty transfer is commonly manifested as an ink-split with part of the design transferring and part remaining on the backing or carrier. Attemptshave been made to remedy this latter limitation by using heavy wax layers but this increased the distortion of the design during transfer and promoted wax staining of the surface being labeled. Heavy image layers which were intended to split have also been used but fine reproduction detail is impossible with such materials. Images with high strength properties overlayed with adhesive coatings have also been disclosed but these are expensive and are difficult to apply with conventional printing equipment. Finally, impermeable paper backing or carriers such as glassine and coated papers have been suggested to overcome the drawbacks of wax transfer coatings but such materials are not entirely satisfactory and increase the cost of the product.

Thus ideally a wax release coat should be inexpensive, be eflective in thin films as a release agent when coated on inexpensive paper, be receptive to high quality printing, resist strike through or migration of an ink design, have low staining properties, resist picking during printing, show no ofiset tendency during storage, and'be easy to apply on production equipment. None of the prior disclosures meet all of these requirements.

According to the present invention, the above requirements and objects are met by a heat transfer com prising a backing and a release coating thereon comprising an oxidized wax obtained as the reaction product of the oxidation of hard, high-melting, aliphatic, hydrocarbon waxes. These oxidized waxes include the oxidation products of both natural and synthetic hydrocarbon Waxes such as petroleum waxes, low-molecular weight polyethylene, and waxes obtained from the Fischer- Tropsch synthesis. The oxidized waxes useful for transfer coatings are those which have melting points between about 50 C. and C.,'saponification values between about 25 and '100, acid values between about 5 and 40, and which have a penetrometer hardness (ASTM D5- 52) below about 15 as measured with 100 grams for 5 seconds at 25 C.

Minor amounts of certain additives such as fillers and resins may be added to the oxidized wax without adverse efiect.

The present invention may better be understood by reference to the accompanying drawing in which Fig. l is an isometric view of the present transfer; and

Fig. 2 is a section on line 2-2 in Fig. 1.

Referring to the drawings, a backing 10 is coated with an oxidized wax Y11 and a design 12 is printed on the exposed surface of the wax. While any convenient backing may be used, paper is preferred for economy. Unlike prior wax transfer disclosures, no sizing is required for the paper before application of the wax and special papers are not required.

The oxidized, aliphatic, hydrocarbon waxes herein disclosed appear to be unique among waxes in having good printing and transfer characterictics. This is believed to be due to the polar nature of such materials which probably comprise a mixture of fatty acids, waxy alcohols, esters, aldehydes and ketones in addition to hydrocarbon wax. These oxidized waxes can be prepared by a. number of well known methods which generally comprise heatingthe hydrocarbon waxes in the presence of oxygen or other oxidizing agents. In addition to these oxidization products, further derivatives, such as esterification products of the oxidized waxes, are included within the scope of this invention.

' The oxidized waxes of the present invention may be applied to the carrier backing by any convenient method such'as by emulsions, hot melts or as solvent solutions.

Emulsions prepared with' alkalies or organic amines are preferred since they are easily formed and give emulsions of low foam-forming characteristics making them easy .to apply with conventional paper coating equipment.

The coated paper is printed with a design by conventional printing equipment such as letterpress, rotogravure, and flexographic presses and with conventional inks including those made from powdered metals. The term design as used herein includes both printing and art work or a combination of both.

The present invention may be more clearly understood by reference to the following examples. All parts are by weight:

Example'No. 1

Fifty (50) parts of Duroxon H-llO, an esterification product ofan oxidized, Fischer-Tropsch wax, available as a proprietary product from the Dura Commodities Corp., is melted. 5 parts of morpholine are added with agitation and the mixture then poured into 280 parts of boiling water. The resulting emulsion is cooled with agitation and is coated on a 50 lb. supercalendered sulfite paper on an air-knife coating machine to give a dry weight of wax of from 1 to 1.5 lbs. per ream (20 x 25 500).

The paper is then printed on the wax side with a glossy, oil-base ink. After the ink has dried, the design is transferred to MST53 cellophane by rolling the cellophane, in contact with the design, over a hot plate at F. with mild pressure. The paper backing is immediately removed while hot, leaving the design firmly attached to the cellophane.

Duroxon H7110 wax melts at 90-95 C. with a solidification point (rotating thermometer) of 80-83 C.

and has-an acid-valueof--15-30,- a saponification value of- 60-75, and a penetration (ASTM D-52) of 2-4 as measured with 100 grams for 5 seconds at 25 C.

After coating with the wax; the paper will havea glossy appearance; will show no signs of tackiness; and will exhibit excellent ink-' receptivity with sharp outline and good" ink-drying properties. design will transfer to the cellophane with only faint staining from the" wax and' without significant distortion;

Example N0. 2

Example N0. 3

Two parts of stearic acid, 3 parts. oftriethanolamine andparts of Cardis320 (Warwick' Wax Co., Long Island City, N. Y.), an oxidized, emulsifiable microcrystalline-wax, aremelted at 100C and poured into 40 parts of 1boiling .water. Theresulting emulsion is chilled with-agitation and applied. to a supercalendered sulphite paper. to give. a coating weight of1-2'lb's.,per ream (20 x .25-500 Cardis 320'. has a melting point of 82 85 C., an acid value of 2830, a saponification value of 75-80, and a penetrometer hardness of .5 7.

The transferof theabove examples will also transfer with good results to materials other than cellophane, such as for example, metal foil, wood, fabric, plastic, glass and the like.

It should beunderstood that the. above disclosure is for the purpose of illustration only andfthat the invention includes all' equivalents and modifications falling within the scope-of theappendedclaims.

1'. A heat transfer comprising a backing and a trans- Substantially-all of the ink fer coating thereon,.said coatingcomprising; an oxidized wax obtained as the reaction product of the oxidation of a hard, high-melting, aliphatic. hydrocarbon. wax, said coating having a melting point between about C. and 110 C., an acid value between about 5 and 40, a saponification value between about 25 and 100, and a penetrometer hardness below about 15 as measured with 100 grams for 5 seconds at 25 C., whereby designs comprising commercial inks can be printed on the surface of the coating by conventional commercial processes and transferred to permeable-or impermeable surfaces by the application of heat and pressure.

2. A heat transfer according'to claim 1 wherein the oxidized wax is obtained by oxidation of the high-melting wax'fraction of the Fischer-Tropsch synthesis.

3. A heat transferaccording to claim 1 wherein the oxidized wax is oxidized, low-molecular weight polyethylene.

4. A heat transfer according to claim 1 wherein the oxidized wax isoxidized, microcrystallinewax.

5. A heat transfer according to claim 1 wherein the transfer coating comprises the esterification product of an oxidized hydrocarbon wax.

A heat transfer comprising a backing and a transfer'coating'th'ereon, a major portion of said coating comprising -an oxidized waxobtained 'asthe reaction product of theoxidation of'a-hard, high-melting, aliphatic hydrocarbonwax, said coating having a melting point between about50'C. and='110 C., an acid'value between about Sand 40, a saponification value between about 25 and 100, and" a penetrometer hardness below about 15' as measured with grams for five seconds at 25 C., and a design 1011 said coating, whereby said'design printed by conventional commercial inks-and processes can be'transferredto permeable-or impermeable surfaces by the ap plication of heat and-pressure;-

References Cited-in the file of this patent UNITED STATES PATENTS 1,990,193 Lohmann Feb. 5, 1935 2,118,915. Butz May 31, 1938 2,219,071 Humphner Oct. 22, 1940 2,471,102 Fish May-24, 1949 2,743,191 Klimkowski et-al. Apr. 24, 1956 2,748,024 Klimkowski et a] May 29, 1956 2,794,040 Annable et al. May 28, 1957

Claims (1)

1. A HEAT TRANSFER COMPRISING A BACKING AND A TRANSFER COATING THEREON, SAID COATING COMPRISING AN OXIDIZED WAX OBTAINED AS THE REACTION PRODUCT OF THE OXIDATION OF A HARD, HIGH-MELTING, ALIPHATIC HYDROCARBON WAX, SAID COATING HAVING A MELTING POINT BETWEEN ABOUT 50*C. AND 110*C., AN ACID VALUE BETWEEN ABOUT 5 AND 40, A SAPONIFICTION VALUE BETWEEN ABOUT 25 AND 100, AND A PENETROMETER HARDNESS BELOW ABOUT 15 AS MEASURED WITH 100 GRAMS FOR 5 SECONDS AT 25*C., WHEREBY DESIGNS COMPRISING COMMERCIAL INKS CAN BE PRINTED ON THE SURFACE OF THE COATING BY CONVENTIONAL COMMERCIAL PROCESSES AND TRANSFERRED TO PERMEABLE OR IMPERMEABLE SURFACES BY THE APPLICATION OF HEAT AND PRESSURE.

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