US 2723468 A
Description (OCR text may contain errors)
United States Patent SHOE HAVING A POLYETHYLENE COUNTER Robert J. Marcy, New York, N. Y., assignor to Endicott Johnson Corporation, New York, N. Y., a corporation of New York No Drawing. Application April 27, 1953, Serial No. 351,597 7 Claims. (Ci. 36-68) This invention relates to the assembly of polyethylene shoe counters in shoes and more particularly to the securing of polyethylene counters within shoes.
It is an object of this invention to assemble a heel counter in a shoe with a tacky adhesive which bonds the counter to adjacent parts of the shoe and permits the counter to disengage from and move in relation to the adjacent parts of the shoe and which rebonds the counter to adjacent parts of the shoe after the relative motion.
It is another object of this invention to providethat the layers adjacent the counter are carried back to shape after deformation by being held onto by at least part of the polyethylene counter and then subsequently readhered to the part of the counter from which they were detached.
These and other objects of this invention will become more apparent upon consideration of the following description.
In my co-pending application Serial No. 223,480, filed April 28, 195 I, now abandoned and which was a continuation-in-part of my earlier application Serial No. 104,529, filed July 13, 1949, and now abandoned, I disclose and describe a shoe counter composed entirely of the plastic compound known and identified as polyethylene. The assembly of this polyethylene shoe counter in conventional shoes by means of conventional shoe assembly methods presents a problem in normal shoe manufacture. This is brought about by the characteristics of the polyethylene compound of which the shoe counter is composed. The counter surface is smooth and impervious to penetration by adhesive chemicals and resistant to reaction with adhesive chemicals. The surface has no tooth for conventional adhesives used in conventional shoe manufacture. Moreover, adhesives which do adhere to the surface of the polyethylene are not suitable for holding the counter to the adjacent parts of the shoe during normal shoe wear.
In incorporating polyethylene counters in shoes it is desirable to have the polyethylene counters fixed in place in the quarter of the shoe without sewing. Thus it is important that the polyethylene counter be fixed in the quarter by adhesive methods. According to this invention, the assembly of a shoe is based upon a last as is customary in all shoe manufacture and assembly. First, an innersole is applied to the last of the shoe, being nailed to it, then the upper of the shoe is assembled. Next, a counter coated with adhesive is placed inside the upper. The assembled upper is placed over the last and with the upper in place on the last, the last is side-lasted which forms the upper on the last in the vicinity of the middle of the shoe and nails the upper to the last. The last and the upper are then placed in the heel lasting machine which forms the heel of the shoe. During heel lasting, the quarter at the rear of the upper is worked to make it snug over the counter. Then the remaining steps are taken to provide a finished shoe. It is a feature of this invention, during the lasting of the shoe subsequent to the insertion of the polyethylene counter in the shoe, relative motion between the counter and adjacent parts of the upper is permitted without preventing or spoiling the securing of the polyethylene to adjacent surfaces in the finished shoe.
It is another feature of this inventionthat after relative movement between the parts of the upper, the layers adjacent the counter are carried back to shape by being held onto by at least part of the counter and then readhered to the areas of the counter from which they had become detached.
One method of fixing a polyethylene shoe counter in a quarter of a shoe, according to this invention, is by coating the counter prior to the insertion in the quarter with an adhesive which forms a permanently tacky surface coating on the smooth, impervious, resistant surface of the polyethylene shoe counter. The coating of this type of adhesive of this invention on the shoe counter remains tacky and pressure sensitive so as to permit a disengagement of adhered adjacent surfaces, a re-arrangement of the relative positioning of the adjacent parts, also a support of the adjacent shoe layers by parts of the shoe counter surface and a subsequent re-adhesion between the polyethylene shoe counter and adjacent surface or surfaces. Thisis important during the heel lasting operation as explained above and in the subsequent use of the finished shoe.
In the accompanying drawing 1 have shown a polyethylene counter of the type disclosed in my aforesaid patent application, Serial No. 223,485), and I have also shown it assembled in a shoe as disclosed therein.
Thus Fig. l is a perspective view of a polyethylene shoe counter held in a hand and illustrating it in deformed position in full lines, and in normal position in dotted lines; and
Fig. 2 is a longitudinal sectional view in elevation of the quarter and heel portion of a shoe having the polyethylene counter therein.
The polyethylene counter 13 may be of any desired shape. It is assembled with the quarter portion 19 of the shoe 10 between the outer layer 12 and the lining 14- and the flange 39 of the counter extends beneath the inner sole 16 and the sock liner 2t). Adhesive bonds 2i and 22 serve to secure the counter to the outer layer 12 and to the lining 14. The adhesive forming the bonds should be of the type disclosed herein.
The tacky pressure sensitive adhesive must be of a nature which provides the adhesive with an adherence to the counter surface greater in strength than the relative film cohesion within the coating of adhesive. The
. adhesives used to provide this tacky pressure sensitive coating should, therefore, be relatively non-film forming. The adhesive must also be sufficiently coherent to resist parallel motion between the adhered surfaces. Other requirements are that the adhesive be adequately flexible and tacky at freezing temperatures and below,
non-toxic, and not stick to an assembiers hands.
The purpose of adhesion between a shoe counter and the quarter of a shoe upper is to prevent a parting of the quarter from the counter which would permit the leather of the quarter to wrinkle and bunch toward the bottom bond is also strong enough to carry the quarter with the resilient polyethylene shoe counter as it returns to normal shape from deformation. At the same time the adhesive of this invention is adapted to re-establish the seal be tween such abutting surface whenever such adhesion becomes disrupted.
Thc adhesive coating which thus seals and reseals the abutting surfaces between the counter and the quarter provides a counter-quarter relationship which will correct the misplacement of the parts that is characteristic of bending, creasing or other misuse of the rear or heel portion of the shoe. If the rear of the shoe is crushed the component parts of the shoe tend to become disassembled. In the assembly of a shoe counter in a shoe of this invention the tacky adhesive coating which is provided reestablishes adhesion between the counter and the adjacent parts of the quarter. If such a re-adhesion does not provide the original arrangement between the parts, the resultant disarrangement is not permanent. In thenormal use of the shoe the subsequent working between the quarter and the counter will cause a second disruption between the adhered surfaces. Subsequent to this second disruption a second resealing between the surfaces will take place. At the time of the second resealing between the abutting surfaces the original disarrangement resulting from the initial bending or creasing will be corrected and the proper arrangement of the parts will be obtained.
In the counter adhesion of this invention the bond also serves to hold some areas of the counter surface and the adjacent layers of the shoe in contact while the polyethylene shoe counter is returning the heel structure to normal shape.
It has been determined that the adhesiveness in this method of assembly is a combination of factors. One of the factors is the permanent tackiness of the adhesive by which the adhesive maintains its adherence both to the polyethylene counter and to adjacent material and permits multiple rescaling without losing its tackiness. Another factor is coherence which provides the adhesive with resistance against relative parallel motion between the adhered surfaces and the relationship between the surface adhesiveness and the film forming characteristics of the adhesive on the shoe counter. Another factor in the tacky adhesive is its pliability under deformation. Still another factor is coherence of the adhesive on partial areas of the counter surface to adhere between the counter and the adjacent material and support the adjacent material on the counter. One of the features of the polyethylene counter as set forth in my above-mentioned co-pending application is the pliability or crushability of the polyethylene counter. The counter wall can be depressed to the point where it is folded almost in half and it will then return to its original shape quickly and without any permanent indication of the deformation. The adhesive employed in assembling the shoe of this invention must comply with these extreme demands placed upon the polyethylene counter and the adjoining shoe structure. The shoe assembling procedure of-incorporating a tacky adhesive coated polyethylene shoe counter in a shoe provides an adhesion of the counter to its adjacent surfaces through all the various deformations to which a shoe might normally be subjected.
The tacky adhesive form of this first type of adhesive used in this invention has permanent tackiness, sufficient coherence to resist parallel motion between adhered surfaces, pliability, and is preferably deposited on the counters from a water base or carrier either in the form of an emulsion or a solution. The dispersion of suitable ingredients has been found to adhere firmly to polyethylene and has been applied in the same manner as conventional shoe counter adhesives. The materials used in this invention do not stick objectionably to the hands of an assembler. The adhesive may be easily removed from the assemblers hands without use of a cleaning agent. The adhesive also is not affected materially by the normally low temperatures applied to shoes. dispersion employed includes a mixture of various resins emulsified in a casein solution from which the adhesive is deposited on the counter by the dipping operation described above. The adhesive may also containin the A tacky adhesive I emulsion a synthetic rubber such as Vistanex. Low molecular weight Vistanex, employed in my invention, is a series of polymers formed by the low-temperature polymerization of isobutylene having a molecular weight of from 10,00020,000. Four types of low molecular weight Vistanex are commercially available: Vistanex LMS having a molecular weight of 9,000-10,000 Staudinger method, average molecular weight of 26,00027,000 viscosity method, and intrinsic viscosity of 0.28-0.33; Vistanex LM-MS having a molecular weight of 10,000- ll,OOO Staudinger method, average molecular weight of 47,00049,000, viscosity method, and intrinsic viscosity of 0.330.34;Vistanex LM-MH having a molecular weight of 1l,000-l3,000 Staudinger method, averable molecular weight of 49,00055,000 viscosity method, and intrinsic viscosity of 0.34-0.37; Vistanex LM-H having a molecular weight of 13,00020,000 Staudinger method, average molecular weight of 55,00098,000 viscosity method, and intrinsic viscosity of 0.37-0.63. It has been found desirable to add 2% Kelgin solution to the emulsion for the purpose of increasing the viscosity and the smoothness of the emulsion. 2% Kelgin solution is a water solution of sodium alginate which serves as a stabilizing colloid.
The adhesive provided by this mixture has a range of properties depending upon the relative percentages of the components. This range of properties of the adhesive provided by the above mixture includes adhesives which are useful in this invention. Within this range of properties adhesives may be provided which have a relatively hard surface and a relatively high cohesiveness within its body ranging to an adhesive which has a relatively soft surface and a relatively low cohesiveness within its body. The limiting factors on the range of properties is a hardness of the adhesive surface which does not have adequate tackiness on the one hand and a lack of cohesiveness against parallel pull in the body of the adhesive on the other hand. In the mixture the ester-type resin provides hardness and cohesiveness to the bond in the assembly of the shoe while a softer resin and the Vistanex provide tackiness and militate against film forming in the adhesive. By the variation of the relative percentages of these components in the adhesive, the effect of the adhesive on the assembly of a polyethylene shoe counter in a shoe can be varied to provide a bond with a relatively non-tacky but considerable inherent cohesive strength on the one hand and an adhesive having a relatively tacky surface but lower internal cohesiveness on the other hand. The adhesiveness of the surface coat is more important than its film forming characteristics.
Certain compounds have been found useful in providing the components of the above noted dispersion. The resins for example may be thermoplastic teipene resins. The ester may be a glyceryl and glycol ester of a polymerized rosin. The synthetic rubber component may be a series of polymers formed by the low temperature polymerization of isobutylene. Other suitable compounds having the same adhesive properties may be added in proportion or substituted in the dispersion. In the following specific example the Piccolyte resins are light colored hydrocarbon thermoplastic terpene resins. Two Piccolyte resins employed in the specific examples below are Piccolyte Resin S-55 and Piccolyte Resin S40. These are products of Pennsylvania industrial Chemicals Corp. having a molecular weight of between 1000 and 1200. Piccolyte S-55 has a softening point of 55 C. and Piccolyte 8-40 has a softening point of 40 C. as determined by the ball and ring method. The Polypale ester 10 is a Hercules Powder Company product and is defined as a glyceryl and glycol ester of polymerized rosin.
The casein solution is prepared by dissolving approximately 6 parts of casein in 54 parts of water containing 1% of ammonia (28%). This is then further diluted with 40 parts of water containing 2% caustic soda.
The resins are melted and, at a temperature-just below 100 C., the casein solution, which has also been heated to approximately 95 C., is added with rapid agitation. It will also be found advantageous to add a water retaining agent in order to slow the drying of the adhesive to conform to the time schedule used in lasting the shoes. These agents may be, for example, one of the vegetable gums such as tragacanth or karaya, or algin or methyl cellulose or any similar material able to absorb several times its weight of Water.
Specific examples of permanently tacky adhesives for use in this invention are as follows:
EXAMPLE I Parts by Weight Percent Piccolyte Resin 8-55 25 21. 5 Polypale Ester 15 13.02 Casein solution 75 65. 5
EXAMPLE H Parts by Weight Percent Piecolyte Resin S-55 32. 5 22 Polypale Ester 17. 5 10. 7 Vistanex 25 15. 9 Casein Solution 82. 5 53 EXAMPLE 111 Parts by Weight Percent Piceolyte Resin 8-55 40 20 Polypale Ester 20 10 Vistanex 50 25 Casein Solution 90 4e EXAMPLE IV Parts by Weight Percent 60 23. 5 30 11. 5 110 41. 5 2% Kelgin Solution 60 23. 5
EXAMPLE V Parts by Weight Percent I 8-40 Piccolyte 47 18 Polypale ester 10.. 24 9. 2 Vistanex LM-H 22 8. 4 Casein S0lution .r. 107 41. 1 2% Kelgin Solution (i0 23. 5
The range in parts by weight of the components in the adhesive are generally within the limits set forth in the following table: v
sets forth a generally intermediate adhesive which has modified tackiness and cohesiveness. The selection of the adhesive is determined by the properties desired of the adhesive in the shoe assembly. Any of the adhesives having the properties of the range of adhesive set forth in the above examples and table may be employed.
The type of adhesive of this invention set forth in the above noted examples provides this invention with the above described advantages. Employing the tacky type of adhesive is one embodiment of this invention. According to another embodiment of the invention fixing a polyethylene shoe counter in the quarter of a shoe is accomplished by precoating the counter with a thermoplastic adhesive cement which is substantially nontacky at room temperature. Thus, previous to its insertion in the upper, the counter of this invention has applied to it a cement. which is thermoplastically adhesive at temperatures above F., and is cooperative with the smooth, resistant surface and other material of the shoe upper. After application of the thermoplastic adhesive cement, the counters are permitted to dry at a temperature below 140 F. to set the adhesive coat on the counter. The counter with the coat thus set is manipulatable and susceptible to handlingin a manner similar to uncoated counters. The coated counter is then positioned in the upper by hand or any of the customary methods. Next, the upper'is side-lasted onto the last. This is followed by heel forming and lasting and toe forming and lasting.
The thermoplastic adhesive is a mixture of organic materials having a lower fusing point than the material of which the counter is formed. The composition is strongly adhesive to the polyethylene shoe counter and it is flexible in thin films even at freezing temperatures. It is preferred that an adhesive composition be employed which has a fusing point in the range of the temperatures normally used in the drying oven in shoe factories.
The thermoplastic cement with which the counter is coated has a tackiness at temperatures above 140 F. The heating of the lasted upper in this step is carried on at temperatures above 140 F. and preferably at temperatures around F. At these temperatures, the thermoplastic cement softens and becomes tacky. It attaches the counter to its neighboring shoe parts which are the quarter on the outside and the quarter lining on the inside. When the lasted shoe is removed from the heating stage, the counter has become adhered to the upper and the quarter lining because of the adhesiveness of the coating. The shoe assembly is then cooled to below 140 F., and the cement on hardening at the lower temperature serves to bond together the counter and the upper on one side and the counter and the quarter lining on the other side. In this way, the counter is fixed in the assembled shoe without the use of other fastening means. It is preferred, in thus securing a polyethylene shoe counter in a conventional shoe, that the adhesive compound fuse in the range of the temperatures in the drying oven, i. e., 140 F. to 240 F., and most preferably, 140 F. to F. These temperatures are critical from two aspects: first, the adhesive should be suificiently low melting to soften and bond the counter into a laminated structure in the oven under the pressure of the shoev last. The second temperature aspect is that the viscosity of a hot-melt type of dipping bath varies inversely with the temperature; the adhesive must melt at a sufiiciently low temperature so that the dipping bath may be heated to a sufficiently high temperature to maintain the viscosity thereof below about 500 centipoises and preferably below 100 centipoises, so that the fiilm of adhesive adhering to the counter will be sufiiciently thin as dictated by economic requirements. Thus, the temperature of the hot-melt dipping bath may range as high as 310 F., but in any case will be insufiicient to soften and deform the molded shoe counter.
The temperature at which the shoe may be heated during the adhesive stage of the assembly depends upon the period of time during which the heating takes place. For example, if the heating is to take place for a period shorter than one-half hour, there is a danger that the adhesion would be incomplete. For that reason, the tem- 7 perature which is most effective is dependent upon'the length of the period of heating. Generally, if the heating period is less than one-half hour, the temperature must be over 160 F. On the other hand, if the temperature is to be around 140 F., the heating period must be correspondingly increased.
The adhesive composition in this second embodiment for securing the polyethylene shoe counter is predominantly a wax with minor rubbery modifiers and minor quantities of resinous modifiers. .The wax components may include the following:
Micro-crystalline paraffin was having a melting point range of 160 F. to 185 F.;
Ordinary crystalline paraffin was having a melting point of 130 F. to 140 F.;
Higher fatty acids, for example, stearic acid, oleic acid or hydrogenated fish oil fatty acids;
Elastomeric film-forming waxy non-oil modified alkyd resins, such as Neolyn #23. Neolyn #23 is a tough, somewhat elastomeric, grease-resistant, non-migrating resin-derived alkyd-type resin having a softening point of about 72 C. determined by the Hercules drop method and a softening point of 58 C. by the ASTM ring and ball softening point method.
Cholorowax 70 is a white, pulverized chlorinated resinous product of Diamond Alkali Company having a melting point of 90 C.,'an average formula of C24H29C121 and an average molecular weight of 10,600.
The rubbery components include various rubbery polymers of the nature of high molecular polyisobutylene, for example, butyl rubber (GR-10), milled natural unvulcanized rubber, and GR-S synthetic rubber. GR-S rubber is a copolymer of butadiene with styrene manufactured according to a Government specification.
GR-l'-70 polybutene synthetic rubber may also be employed in this adhesive as illustrated by one of the following examples.
GR-I-70 is a butyl rubber which is a synthetic rubber prepared by copolymerization of isobutylene and small percentages of butadiene or other dienes such as isoprene.
The resinous components are made up of a thermoplastic fusible resin, for example, polystyrene resins, polyterpenes and bituminous resins. Representative resins include polymerized beta-pinene (Piccolyte), bituminous resin from Utah coal (RBH Resin 51OL), and modified polystyrene resins.
The composition may be prepared by solution in a volatile solvent for application to the polyethylene counter. The composition may also be prepared by compounding the composition at a temperature sufiicient to bring about the formulation of the composition. In formulating the melted type of the adhesive the rubbery component and the paraffin wax are mixed together in a heavy-duty heated dough mixer of the Werner-Pfleiderer type. The resultant rubbery batch and the other components of the composition are melted together in a steam jacketed kettle and mixed until a homogeneous material is obtained.
The adhesive type solvent is formulated by solution of the components in the solvent. The mixture is agitated at ordinary room temperature or slightly elevated temperatures up to 140 F. An added reflux of the solvent may be made, if desired. When a homogeneous solution is obtained the adhesive composition is cooled to room temperature and may be used for dipping or spraying.
The following table shows the components of the melted adhesive and the solvent adhesive, by weight:
Table II Solvent 1 Solvent 2 Solvent The following examples illustrate the specific components of the melted type composition:
EXAMPLE VI Parts by weight GR-I-70 polybutene synthetic rubber 5.5 Crystalline, parafiin wax (melting point F.) 16.5 Microcrystalline parafiin wax (melting point F.) 63.7 Picco 1O coumarone-indene resin 20 EXAMPLE VII Parts by weight Vistanex B-80 polybutene (80100,000 molecular weight) 5 Crystalline parafiin wax (melting point 130-140 F.) 15 Microcrystalline paraffin Wax (melting point 175- 185 F.) 60 Piccolyte S-10 polyterpene 16 The following examples illustrate the specific components of the solvent type of adhesive composition:
EXAMPLE VIII Parts by weight 6R4 synthetic rubber 8 Quarter as used in the above description refers to both the outer layer and the lining of the quarter unless otherwise indicated in the description.
Various modifications may be made in this invention without parting from the spirit thereof as set forth above in the description of the advantages of this invention. The examples set forth are for the purpose of illustration of typical adhesive compositions used in this invention. It is therefore intended that the invention be limited by only the appended claims.
This application is a continuation-in-part of my copending application Serial Number 217,405, filed March 24, 1951, now abandoned.
1. In a shoe structure, the improvement which comprises a shoe quarter portion of a size and shape to embrace the heel of a wearer and made of a material which will become deformed when bent or creased, a one piece molded heel counter disposed inside the quarter portion in intimate contact therewith, composed of shape retaining, relatively stiff and resilient plastic polyethylene which will bend and flex without fracturing or taking a permanent set, said quarter portion being tightly stretched and fitted around the heel counter whereby ,the quarter portion is maintained in the shape and contour of the heel counter, an impermanent adhesive bond between the contacting surfaces of the quarter portion and the heel counter and a non-film-forming adhesive providing said bond, said adhesive being greater in adhesive strength than in film forming cohesion whereby the quarter portion and heel counter are normally maintained in fixed relative position but may shift relative to each other when submitted to stresses as in bending and flexing.
2. In a shaped heel construction for a shoe, a resilient flexible preformed polyethylene shoe counter positioned in the heel of said shoe, a layer of said shoe adjacent and extending over and formed by said polyethylene shoe counter, said polyethylene shoe counter being severely deformable and returning to the preformed shape rapidly, a smooth, impervious, resistant surface on said polyethylene shoe counter, said adjacent layer being attached to said polyethylene surface by a permanently tacky surface coating on said smooth, impervious, resistant surface, an adhesive comprising said permanently tacky surface coating being greater in adhesive strength than in film forming cohesion, said surface coating serving to maintain adherence of said layer to said polyethylene surface in a deformed shape and after return to the preformed shape of the shoe counter after deformation.
3. A shoe including in the heel portion a flexible, resilient, polyethylene shoe counter capable of doubling by folding and rapid return to original preformed shape, a layer of said shoe adjacent and extending over said polyethylene shoe counter shaped by the preformed shape of said polyethylene shoe counter, a smooth impervious, resistant surface on said polyethylene counter, a permanently tacky adhesive coating on said polyethylene surface adhering said layer to said polyethylene surface, the adhesive coating allowing a disengagement of said layer from said polyethylene shoe counter upon deformation of said shoe counter and providing readhesion of said shoe counter surface and said layer after deformation whereby said polyethylene shoe counter and said layer are severely deformable and are adhered together after said deformation. I
4. A shoe construction adapted to withstand severe deformation including a flexible, resilient, preformed, polyethylene shoe counter, at least one layer of shoe material adjacent, extending across and formed by saidpreformed polyethylene shoe counter, said layer being less resilient than said polyethylene shoe counter, said polyethylene shoe counter being deformable without permanent shaping and rapidly returnable to the original preformed shape, a permanently tacky adhesive coating on the surface of said polyethylene shoe counter adhering said layer to the surface of said shoe counter before, during and after deformation of said polyethylene shoe counter and said adjacent layer.
5. A shoe construction as claimed in claim 4 in which said permanently tacky adhesive coating comprises a nonfilm forming adhesive greater in adhesive strength than in film forming cohesion.
6. In a shoe having a shaped heel portion, the combination of a layer of material for embracing the heel of a wearer and made of a material which will become deformed when bent or creased, a resilient, pliable, polyethylene plastic shoe counter positioned within said shoe adjacent said layer of material and having greater resiliency than said layer and sufficient resiliency to overcome deformation in the shape of said layer, a pliable bond attaching said counter to said layer at least equal in pliability to said shoe counter, a non-film forming adhesive providing said pliable bond, said adhesive being greater in adhesive strength than in film forming cohesion and having tackiness to reattach said counter and said layer after separation and cohesiveness to maintain said pliable bond against shear between said counter and said layer in normal wear of said shoe.
7. In a shoe having an upper with a quarter portion having a flexible inner lining layer and a relatively stiffer outer leather layer, the combination of: a solid plastic polymerized polyethylene shoe counter being capable of doubling by folding and rapid return to original preformed shape and having a smooth, impervious, chemically resistant outer surface; a leather layer adjacent and extending over said shoe counter and being shaped by the preformed shape of said shoe counter, a permanently tacky adhesive coating composed of a dispersion of thermoplastic terpene resin, an ester of polymerized rosin and a low temperature polymer of isobutylene on said surface, said coating having a pliability at low temperatures, coherence to provide resistance against rela tive parallel motion over said inner and outer layers over the surfaces of said shoe counter, said outer leather layer being disposed adjacent and extending over said adhesively coated surface of said counter and releasably adhered thereto by said coating to allow disengagement of said layer from said polyethylene shoe counter upon deformation of said shoe counter and readhesion after return to original shape, whereby said polyethylene shoe counter and said layer are severely deformable and are adhered together after said deformation.
References Cited in the file of this patent UNITED STATES PATENTS 1,836,825 Stuart Dec. 15, 1931 1,948,127 Perry Feb. 20, 1934 2,010,092 Lawson Aug. 6, 1935 2,114,486 Gialdini Apr. 19, 1938 2,145,410 Thurston Jan. 31, 1939 V FOREIGN PATENTS 409,941 Great Britain May 10, 1934 OTHER REFERENCES Plastics (Chicago), September 1944, pp. 39, 40, 42, 43 and 100. (Copy in Div. 50.)