US 3340086 A
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Description (OCR text may contain errors)
Sept 5,1967 J. GROAK 3,340,086
' TRANSFER SYSTEMS Filed March 24, 1966 I '11 m v1x: Y szz $2257 .38 8 B B B my F F F F INTERMEDIATE I I1 A I I1 LAYE R v i I A 2:51a I A sszzc 3 Sheets-Sheet 1 Sept. 5, 1967 J. GROAK 3,340,086
TRANSFER SYSTEMS Filed March 24, 1966 5 Sheets-Sheet 2 VIIIIIIIIIflIII/IIIIIIIL 5 4 sosz ZIIIIIIIIIIIIIIIIIIIIIIA no-ofiuo-oh-a-o-om 6O mmwnmmw Sept. 5,1967 J. GROAK 3,340,086
TRANSFER SYSTEMS I Fil ed March 24, 1966 v 5 Sheets-Sheet 5 O O O m\\\\\\\\\\\\\\\\\\\\\w United States Patent TRANSFER SYSTEMS Josef Groak, St. Louis, Ave. de Sully 1, La Tour de Peilz, Vaud, Switzerland Filed Mar. 24, 1966, Ser. No. 561,301 Claims priority, application Great Britain, Aug. 17, 1959,
8 Claims. (Cl. 11736.4)
The present application is a continuation-in-part of my co-pending application Ser. No. 138,553 filed Sept. 14, 1961, now abandoned, which is itself a continuationin-part of my application Ser. No. 49,750, now abandoned.
The present invention concerns improvements in transfer systems, that is to say systems comprising a base and transferable material thereon of which at least part can be caused to become detached from the said base and adhere to a receiving surface. Such systems are commonly employed as copying and manifolding materials, but can also be utilised in, for example, typewriting, printing, and hectographic processes and in such processes as the production of printing plates and offset plates. Transfer may not only be effected by simply mechanical pressure, but may also be initiated by heat, as in hot transfer techniques or by electrostatic pressure.
Conventional transfer materials such as carbon paper and carbonised manifolding materials, consist of a base sheet, usually paper, on which is spread a layer of a transfer composition which is substantially homogeneous and contains a pigment or dye and a material, such as an oil or soft wax, which renders the layer tacky and thereby readily adherent to a second sheet of paper. A disadvantage of such materials is the ease with which they can be smudged. They also tend to deteriorate during storage, owing to drying-out of the tacky layer. Moreover the transfer composition must usually be applied to the base sheet in the hot state, using a non-porous paper of special properties.
In an effort to overcome the smudging problem, previous proposals have been made (for example in Patent No. 2,912,344 to Newman et al.) for the provision of additional layers which are either uncolored or are less tacky or relatively hard. Such transfer materials, however, still rely on the presence of at least one tacky layer to secure transfer, and thus do nothing to avoid the disadvantages of deterioration on storage or difliculty of production.
It is an object of the present invention to provide a transfer system in which transfer is effected by physical attraction or affinity between essentially dry layers of material and which are not subject to the above mentioned disadvantages.
It is a further object of the invention to provide a transfer system which, because it does not rely on tacky or non-drying formulations, has great flexibility as regards the number of layers employed and the variations possible in the distribution of record pigments and other materials in the various layers.
I have found that dry, thin films or layers of organic polymers exhibit an afiinity for one another and, in many cases, for paper, that is, they tend to adhere to one another (or to paper) when pressed together, and that this 'aflinity makes possible a new type of transfer system which includes no tacky or non-drying layers.
Furthermore, I have found that one or more such dry, non-tacky layers on the surface of a base or carrier sheet can by reason of this affinity be caused to adhere to a receptor surface under marking pressure, as by a writing, typing or other instrument, and that the pressured areas of the dry, non-tacky layer will upon separation of the base sheet from the receptor surface remain adherent to 3,340,086 Patented Sept. 5, 1967 the receptor surface (that is, be transferred thereto) if the said dry, non-tacky layer is initially secured to the base sheet by a readily di-sruptable bond. Such a bond is provided according to the invention by a dry, discontinuous, essentially particulate, frangible layer of low cohesion on the surface of said base sheet, said one or more dry, non-tacky cooperating layers being applied over said frangible layer.
By a frangible layer is meant a relatively hard and brittle layer which can readily be broken or disrupted and has a low cohesion such that when a force is exerted over a given area of the layer tending to break the said area away from the remainder of the layer, material from the said area will part readily from the material of the re mainder of the layer at the boundaries of the said area. The system is such that pressure, for example by writing, typewriting or printing, of the base sheet and the frangible layer on to the receptor surface, with the cooperating layer interposed, and subsequent removal of the base sheet, causes the pressured area of the cooperating layer, usually accompanied by at least part of the frangible layer, to be removed over the whole of the said area and to be retained by the receptor surface.
The preferred frangible layer consists of or contains discrete fine particles of a hard resin or synthetic resin. The resin should be one which does not exhibit appreciable flow at normal temperatures, as such flow can in time affect the discontinuity of the layer; for this reason synthetic resins employed for this purpose should preferably be substantially unplasticised. Non-porous paper of special quality is not essential for the production of materials with such discontinuous layers, and porous, matt or poorly sized papers can be used provided that sufficient of the material of the discontinuous layer is applied to build up at least a very thin complete layer above the surface of the paper. Frangible layers of synthetic resin have the advantage of an almost indefinite storage life. When paper or the like is used as the base material, it is preferable that the material of the frangible layer should be non-ionic or anionic, since cationic materials have a comparatively high afIinity for cellulosic materials. The particle size of the layer of fine particles should preferably not exceed one and a half microns.
Although mechanical procedures, for example printing methods, can under some circumstances be adopted for generating the discontinuity of a frangible layer, the preferred method of preparation of such a layer is by applying a coating of a dispersion of the hard, brittle material on the surface of the base and thereafter drying the coating. In emulsions of hard synthetic resins suitable for this method of application, one phase, namely the resin phase, is discontinuous, and remains discontinuous on drying the coating provided the temperature of drying is not excessive. The particle size of the resin in the dispersion is preferably not greater than about one micron.
The frangible layer may be strengthened, to facilitate handling and storage of material with an exposed frangible layer, for example by blending with a high meltingpoint acrylate resin, an emulsion of a polymerised terpene resin or a butadiene copolymer. Discontinuous layers are formed from such blends at room temperature or slightly elevated temperatures.
The cooperating layer which adheres to the receptor surface in the act of transfer must have affinity for the receptor surface and may thus be termed a transfer-inducing or activating layer. In an alternative arrangement, a transfer-inducing or activating layer can be present on the surface of the receptor sheet, in which case it will suflice for the then outermost layer on the base or carrier sheet to have affinity for the transfer-inducing material and it need not have substantial affinity for the untreated material of the receptor sheet itself (for example, paper). In this latter arrangement, the transfer-inducing material can be regarded from another point of view as itself constituting the receiving surface, rather than the underlying paper or other structural component of the receptor sheet.
A transfer sheet of which the outermost layer has negligible affinity for the actual material of the intended receptor sheet, for example paper, will not mark off inadvertently on untreated paper.
Where more than one of said cooperating layers is present on the base sheet, the outermost of which is a transfer-inducing or activating layer having direct affinity for the receptor surface, the other cooperating layer or layers are herein termed intermediate layers, from their position between the frangible layer and the activating layer. The same term, intermediate layer is also applied to any cooperating layer on the base sheet when a transfer-inducing or activating layer is formed on the receptor sheet, because such a cooperating layer is still disposed between frangible and activating layers in the complete assembly, and "the same formulations can be used in its formation.
Since it is dry and not tacky, the activating layer will not usually have noticeably adhesive properties provided it has adequate affinity for the receptor surface with which it is intended to be used, and for the frangible layer or, if present, the outermost intermediate layer. It is preferably but not essentially composed of a synthetic resin which forms a continuous film, although other organic thermoplastic substances can be used. When a resin with appreciable flow properties is applied in the form of a dispersion or emulsion, a continuous film is usually formed on drying, unless the special precautions taken in the production of the frangible layer are observed. Where the activating material is to be applied to the receptor sheet, coating can be avoided by incorporating the transfer-inducing substance or substances in the pulp in the paper-making process. Resins used in activating layers may advantageously be plasticised. Examples of suitable resins for use with a receptor surface of paper or like material are polyethylene, plasticised polystyrene, acrylic resins, polymerised tervpene resins, and polyamides, or certain copolymers or mixtures thereof. At least part of such resins can be replaced by a hard, dry wax, in particular where the activating material is applied to the receptor surface. An activating layer of synthetic resin will have an almost indefinite storage life.
When the layers comprised by a system according to the invention are applied in the form of resin dispersions or emulsions they may be applied by a variety of processes such as printing, coating, dipping, rolling, spraying. The coatings may be dried in air at room or somewhat elevated temperatures or, for example, by vacuum or cool forced circulation methods. Electrostatic or transfer methods of application can be used in suitable cases. The layers may cover the whole of the surface to which they are applied, for example one side (or both sides) of a sheet of paper, or some or all of the layers may be applied only to restricted areas. For example, one face of a sheet may be coated all over with frangible and intermediate layers, and an activating layer may be printed over selected areas of the sheet or on selected areas of a second sheet intended for use with the coated sheet. The configuration of the restricted areas can be selected so that a pattern is formed by simple transfer. It is also possible to build up by way of intermediate layers a design in relief, which can be transferred by simple pressure when covered or opposed by an activating layer.
The layers may be colourless, translucent or white, or they may contain colouring matters or other record materials. Thus when a system according to the invention is utilised as a manifolding material, a dye or pigment may be included in one or other of the layers on the back of an upper sheet. If the outermost layer is an activating layer, the colour will mark off to give a record on any receptor surface for which the given activating layer has affinity. If the outermost layer is an intermediate layer having no affinity for the untreated receptor material, the colour will be transferable only to a surface prepared with an activating layer. It is possible to include over the frangible layer a layer of pigment unbound by resin since a following layer of resin, such as will form an intermediate layer, can penetrate the powder layer and bond it to the frangible layer beneath.
An outer layer may contain a masking colour which on the unused material conceals a record colour contained in an inner layer. The record colour may be contained in the frangible or an intermediate layer, and the masking colour in an intermediate or'the activating layer. Two reeord colours may be incorporated, for example one in the frangible and one in an intermediate layer.
A reverse material can be prepared, in which a coloured base or coloured base layer is covered by a frangible layer, a masking colour being incorporated in the frangible layer or in an overlying layer. When an activating layer is present either as the overlying layer or on the back of an upper sheet, pressure will cause the masking colour to be stripped from the base to reveal the colour beneath.
The system according to the invention can be applied to both sides of a carrier or base sheet. Thus one face may bear transferable material comprising a frangible layer and at least one cooperating layer, and the other face may bear a transfer-inducing or activating layer therefor. In another possible arrangement, the upper surface of the base sheet is coloured and forms part of a reverse system as described in the preceding paragraph, while the lower face of the sheet bears a normal transfer system. Such a sheet will at the same time make a record mark on an underlying sheet while receiving a corresponding mark on its own upper surface. When such a sheet forms part of a business or form set or block, only every other sheet requires coating according to the invention, with consequent economies in production.
A particularly advantageous material is obtained where the frangible layer is covered successively by a single intermediate layer containing a record colour and an outer layer which is an activating layer and at the same time contains a masking colour. By this means there is provided a clean one-time 'manifolding material which will mark off on any appropriate untreated receptor surface, for example a paper surface, and in the production of which only a few simple steps are involved. A corresponding material, the production of which is even simpler, is obtained where a coloured base sheet is covered by a frangible layer and an outer layer which is an activating layer and at the same time containing a masking colour.
The layers of a system according to the invention may contain reagents (provided they do not have deleterious effects on the materials of the layers), for example colourforming reagents. The layers of a system may provide protective coatings to shield underlying layers of other materials which become accessible when the transferable layers of the system according to the invention are removed by pressure. For example, a clean hectograph carbon paper can be produced by covering a layer of a spirit-soluble hectographic ink successively by a frangible layer and an intermediate or activating layer, used respectively in conjunction with a sheet backed by an activating layer or an untreated sheet.
Record materials other than colouring matters, suitable for use with systems according to the invention include material detectable by physical methods, such as mechanical sensing, magnetic or electrostatic detection, or by chemical methods. For example, a material containing 10% finely divided magnetic oxide or iron (Fe O is suitable for use with a magnetic sensing head.
The invention will be further described by way of example with reference to the accompanying drawings, together with examples of transfer systems according to the invention.
In the drawings:
FIG. 1 is a diagram showing by way of example six simple arrangements incorporating transfer systems according to the invention; 7
FIG. 2 shows in diagrammatic cross-section three stages in the formation of a transfer mark with a system as described in Example 1 below;
FIG. 3 shows in diagrammatic cross-section a system as described in Example 2 before and after the application of pressure;
FIG. 4 shows in diagrammatic cross-section a system as described in Example 3 before and after the application of pressure;
FIG. 5 shows in diagrammatic cross-section a system as described in Example 5 below before and after the application of pressure;
FIG. 6 shows in diagrammatic cross-section a system as described in Example 6 before and after the application of pressure;
FIG. 7 shows in diagrammatic cross-section a system as described in Example 7 below before and after the application. of pressure, and
FIG. 8 shows in diagrammatic cross-section a system as described in Example 8 below before and after the appli cation of pressure.
In FIG. 1, B denotes a base material, R a receptor material, F a frangible layer having relatively low cohesion, relatively low adhesion to B, and negligible affinity for R, I an intermediate layer showing adhesion to F but negligible affinity for R, 1 a first intermediate layer showing adhesion to F, I a second intermediate layer showing adhesion to 1 but negligible aflinity for R, and A an activating layer with affinity for R and for F, I or 1 The arrangements shown at I, II, and III employ a receptor surface R prepared by the application of the activating layer A, and with such arrangements no mark will be obtained when the base is pressed with normal pressures against an untreated receptor surface, since the frangible layer F (in I), the intermediate layer I (in II), and the second intermediate layer I (in III) have negligible aflinity for the receptor material itself. If the frangible layer F is particularly weak, the arrangement I will suffer from the disadvantage of the vulnerability of the frangible layer ,when exposed in the finished material.
The arrangements shown at IV, V and VI have the activating layer A as the final layer applied to the base material B. These systems will mark off on an untreated receptor surface, as indicated in the figure.
The following examples use systems as shown in II-VI in FIG. 1. In Examples 1, 2, 3, and 4 the record colour is a black pigment composition. This pigment composition can be replaced by any other pigment or dye which does not dissolve in or bleed into other layers of the system. All quantities are given in parts by weight.
Example 1 Frangib'le layer: Parts High M.P. unplasticised polystyrene emulsion,
non-ionic (Vinamul N.710) 100 Carbon black, 35% paste in water Blue pigment, aqueous paste (SPV blue paste) 4 Activating layer: Parts Low M.P. polyethylene emulsion, solids 100 Carbonblack paste 14 The resulting material is a. one-time manifolding material; the layers are clean to handle, and give excellent mark on unprepared paper under the pressure of a writing,
typewriting, or printing instrument. The colour does not show appreciably on the face of thin paper.
The structure and operation of the material are illustrated diagrammatically in FIG. 2, where the three diagrams A, B and C represent respectively the material 20 and a sheet of unprepared paper 21 before the application of pressure, the pressing of the material in contact with the paper over a predetermined area, and the withdrawal of the material leaving a mark on the paper. The system corresponds to that shown at IV in FIG. 1, the base sheet of paper 22 carrying the pigmented frangible layer 23 of polystyrene particles, on which is superposed the pigmented activating layer 24 of polyethylene. Pressure by the instrument 25 causes an area of the pigmented polyethylene layer to adhereto the unprepared paper 21, and on withdrawal of the paper (as in C) the affected portion 26 of the polyethylene layer 24 breaks away, carrying with it a portion of the polystyrene layer 23, and remains adherent to the paper 21 to provide a visible mark.
Example 2 Frangible layer: Parts High M.P. unplasticised polymethyl methacrylate emulsion, non-ionic (Texicryl P8323) Butadiene copolymer emulsion (Butakon BCL/C) 10 Polyacrylate thickener (Texigel SPAS) 2 Water 10 are mixed and applied by roller or air-knife coating to the surface of a sheet of paper and dried.
First intermediate layer (record-colour layer): Part-s Polymerised terpene resin (Dresinol 100 Black pigment paste (SPV black paste) 12 Blue pigment paste 1 are mixed, and a layer applied over the frangible layer and dried. If desired, the mixture may be thickened with a polyacrylate thickener, for example 1% to 3% of Texigel PS253A.
Second intermediate layer (masking layer): Parts Titanium dioxide, 60% paste in water 100 Polystyrene emulsion (Vinamul N710) i 18 Ethyl acrylate emulsion (Texicryl A950) 20 Polymerised terpene resin emulsion (Dresinol 155) 10 Polyacrylate thickener (Texigel PS253A) 2 are mixed, and a layer applied over the first inter-mediate layer and dried. The resulting sheet has a clean white appearance in the untreated side, and will not mark off on untreated paper.
Activati0n.-A surface on which the material will mark can be prepared by applying to the face of a sheet of paper the following composition, and drying it at room temperature.
Parts Polyethylene emulsion, 20% solids 100 Ethyl acrylate emulsion (Texicryl A950) 24 Polyacrylate thickener (Texigel PS253A) 12 Example 3 A sheet of paper is coated successively with a frangible layer and first and second intermediate layers as described in Example 2. Thereafter a coating is applied of the activating composition also described in Example 2, and th coating dried at room temperature. 1
The resulting material has a clean, almost White appearance on its treated surface, and gives excellent marks on untreated paper surfaces.
The structure and operation of the material are illustrated in FIG. 4, A and B, where the material 40 consists of the base sheet 42, the methacrylate layer 43, the pigmented terpene resin layer 47, the pigmented polystyrene/ ethyl acrylate layer 48 and the unpigmented activating layer 44. The system thus corresponds to that shown at V1 in FIG. 1. After the application of pressure, the portion 46 of the layer 44, carrying portions of the layers 48, 47 and 43, remains adherent to the paper 41.
Example 4 A material is prepared by the method described in Example 2 or 3, with the substitution of the following composition for that used as the activating layer in those examples:
Parts Polymerised terpene resin emulsion (Dresinol 155) 12 Ethyl acrylate emulsion (Texicryl A950) Acrylic copolymer emulsion (Texicote P5251) 5 Terpene resin emulsion (Dresinol 215) 2 Water 20 Polyacry-late thickener (Texigel PS253A) 3 The resulting material corresponds in structure to that of Example 2 or 3, and is equally effective.
Example 5 The following layers are applied to the face of a sheet of paper coloured with a colouring matter which will not dissolve or bleed into the layers.
Frangible layer: Parts High M.P. methyl methacrylate resin emulsion (Vinamul N323) 100 Polyacrylate thickener (Texigel PS253A) 4 are mixed until the viscosity develops, applied by roller or air-knife coating and dried at room temperature.
Intermediate layer (masking layer) A coating of the composition described as the Second intermediate layer in Example 2.
The resulting material has a white surface which can be stripped off by transfer under pressure to the activated undersurface of a second sheet placed over the material. The activating layer on the second sheet can be that described under Activation in Example 2. As an alterna tive, the activating layer may consist of a layer of a high melting-point parafiin wax.
The structure and operation of this material is illus trated in FIG. 5, A and B, where the material 50 consists of the pigmented base sheet 52 carrying the methacrylate layer 53 and the pigmented polystyrene/ethyl acrylate layer 58. To this is applied an upper sheet 51, the underside of which is provided with an activating layer 54 of polyethylene and acrylates. The arrangement thus corresponds to II of FIG. 1 (inverted), and the mark is formed by the removal on the sheet 51 of a portion 59 of the masking layer 58, thus exposing to view the pigment of the base sheet 52.
Example 6 As an alternative to the material of Example 5, the activating layer can be superposed on the intermediate layer of the material, to give an activated material from which the white masking can be stripped by pressure through untreated paper placed over the material.
This alternative arrangement corresponds to that shown at V in FIG. 1 (inverted), and includes a mate-rial 60 consisting of a base sheet 62, a frangible layer 63, a pig- 8 after local pressure has been applied to the upper surface of the sheet 61.
Example 7 The following is an example of a particularly advantageous one-time manifolding material. Frangible layer: Parts Polymethyl methacrylate emulsion (Texicyl P5323) Butadiene copolymer emulsion (Butakon are mixed and applied by roller or air-knife coating to the surface of a sheet of paper and dried. A suitable coating weight with an average paper is of the order of 1 /22 g./m.
Intermediate layer (record colour): Parts Polystyrene emulsion (Vinamul N710) 114 Polyvinyl alcohol, 10% aqueous solution Ethyl acrylate emulsion (Texicryl A950) l9 Polymethyl methacrylate emulsion (Texicryl P5323 38 Black pigment paste VS, 22% solids (I.C.I.) 57 Superfine graphite powder 2 are mixed and a layer applied over the frangible layer and dried. A suitable coating weight is of the order of l-l /2 g./m.
Activating layer (masking layer): Parts Polyethylene emulsion (30% solids) 100 Rutile titanium dioxide (RUNA RHZO) 26 A useful material which is particularly simple to prepare uses a coloured base sheet which is covered by a frangible layer and an activating layer containing a masking pigment, the composition of these layers being as described in Example 7.
The resulting material shows record marks where the white masking layer is transferred to an overlying paper sheet, as illustrated in FIG. 8. (The system corresponds to IV in FIG. 1, inverted.) The material 80 consists of a pigmented or other coloured paper sheet 82 carrying a frangible layer 83 and a white pigmented activating layer 84, parts of which layer are transferred by local pressure to the under side of an overlying paper sheet 81.
The polystyrene and polymethyl methacrylate emulsions used in the foregoing examples form discontinuous films on drying at room temperature and the polystyrene has a softening point in the region of to the methacrylate in the region of to C. The polystyrene used has a particle size of about one micron or slightly below, the polymethyl methacrylate a size of about half a micron.
What is claimed is:
1. A transfer sheet comprising a carrier sheet having opposite first and second faces, a hard, non-smearing and non-staining color-containing color layer applied to one of said first and second faces, and a color-transfer-inducing layer having adhesive characteristics covering said color layer, said color layer having sufiicient hardness so as to prevent transfer of the color in said color layer to writing paper upon application of ordinary Writing pressure to t e oth r of said first and second faces of said carrier sheet in the absence of said transfer inducing layer, said color, however, being capable of being transferred to writing paper upon application of ordinary writing pressure to said other face of said carrier sheet in the presence of said color transfer inducing layer, said color-transfer-inducing layer essentially consisting of adhesive l-ow molecular weight polyethylene applied in the form of a dispersion in a liquid, said transfer sheet being adapted to be placed in contact with a color-receptive surface whereby, upon application of pressure to the other one of said faces, color of said color layer is transferred to and anchored at said color-receptive surface due to the transfer inducing adhesive action of said polyethylene layer.
2. A transfer system comprising a carrier sheet having opposite first and second faces, a hard, non-smearing and non-staining transfer layer which has no appreciable adhesive properties but which has affinity under ordinary writing pressure for a transfer-receptive surface, and a pressure-disruptable bond which joins said transfer layer to one of said first and second faces of said carrier sheet and which consists of a hard, brittle discontinuous layer of low cohesion, readily disrupted by ordinary writing pressure, comprising discrete fine particles of a hard resin, said transfer layer being capable of being transferred to said transfer-receptive surface by application of ordinary writing pressure to the other face of said carrier sheet to disrupt said bond, and said transfer layer being adapted to be placed in contact with said transfer-receptive surface whereby, upon application of writing pressure to said other face of said carrier sheet, said discontinuous bonding layer is disrupted over the pressured area, thus releasing the pressured area of the transfer layer from the carrier sheet and permitting the pressured area of the transfer layer to be retained by the receptive surface.
3. A transfer system according to claim 2 wherein the transfer layer has aflinity for writing paper under ordinary writing pressure.
4. A transfer system according to claim 3 wherein the transfer layer is composed of a plurality of strata, the stratum most remote from the bonding layer having no appreciable adhesive properties but having affinity for writing paper under ordinary marking pressure, and a record material being contained in another stratum of the transfer layer.
5. A transfer system according to claim 2 wherein a record material is contained in the transfer layer.
6. A transfer system according to claim 2 wherein the face of the carrier sheet adjacent to the bonding layer is colored, and the transfer layer masks the color of said face.
7. A transfer system according to claim 2 that comprises a receptor sheet having a transfer-receptive surface for which the transfer layer has affinity.
8. A transfer system according to claim 2 wherein the transfer layer is composed of a plurality of strata one of which contains a record material and another of which, more remote from the bonding layer, masks the color of said record material.
References Cited UNITED STATES PATENTS 1,864,097 6/1932 Sherman 11736.4 2,318,096 5/1943 Quick 11736.7 2,729,575 l/ 1956 Newman 1173'6.4 2,777,781 1/1957 Kordig et al. 11736.4 2,872,340 2/1959 Newman et al. 117--36.4 3,034,918 3/1962 Cook et al. 11736.4 3,062,676 -1 1/1962 Newman et al. 117-36.4 3,087,832 4/1963 Fogle 1l736.4
FOREIGN PATENTS 501,983 3/1939' Great Britain. 855,912 12/ 1960 Great Britain.
MURRAY KATZ, Primary Examiner.