US 2180924 A
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Description (OCR text may contain errors)
NOV. 2l, 1939. El W. DUNBAR 2,180,924
RUBBER FOOTWEAR Filed Feb. 24, 1957 4 Sheets-Sheet l ATTORN EY Nov. 21, 1939. E, w. DUNBAR 2,180,924
RUBBER FO OTWEAR Filed Feb. 24, 1957 4 Sheets-Sheet 2 ATTORNEY Nov. 2l, 1939. E w. DUNBAR RUBBER FOOTWEAR 1937 4 Sheets-Sheet 3 Filed Feb. 24
ATTORNEY Nov. 21, 1939. E w, DUNBAR 2,180,924
RUBBER FO OTWEAR Filed Feb. 24, 1957 4 Sheets-Sheet 4 Ei 15W Ufm M 24 23 ATTORNEY Patented Nov. 21, 1939 UNITED STATES RUBBER FOOTWEAR Ernest W. Dunbar, Hudson, Mass., assgnor to Cambridge Rubber Co., Cambridge, Mass., a' corporationof Massachusetts e Application February 24, 1937, Serial No. 127,426
'I'his invention relates to rubber soled shoes and to the parts of such shoes. It is more especially concerned with the bottom structure of footwear of this type.
Objections often raised to the use of rubber shoes are the facts that they burn the bottoms of the feet of some individuals, or cause the feet to sweat excessively, and the further fact that these shoes are relatively heavy. On the other hand, a large proportion of the purchasing public prefers shoes with rubber bottoms because of the cushion effect which they afford, the better grip on the ground which they give, and their superior waterproof and wearing properties.
The present invention aims to improve rubber-soled shoes with a view to eliminating the objectionable features above mentioned, while still preserving the advantages of footwear of this type.
The nature of the invention will be readily understood from the following description when read in connection with the accompanying drawings, and the novel features will be particularly pointed out in the appended claims.
1n the drawings,
Figure 1 is a perspective view of an outing or beach shoe embodying features of this invention;
Fig. 2 is a. vertical, sectional view of a portion of the sole structure of the shoe shown in Fig. 1;
Fig. 3 is a similar'view through the entire bottom of the shoe;
Fig. 4 is a transverse, sectional View through the forepart of the shoe;
Fig. 5 is a side view of a portion of the binder strip used on the outsole;
Figs. 6 and '7 are perspective and edge views, respectively, illustrating steps in the process of manufacture of elements of the shoe bottom;
Fig. 8 is an edge view showing a further step in this process;
Fig. 9 is a perspective view of a mans shoe including a bottom embodying features of this invention;
Fig. 10 is a vertical, sectional view showing a diiferent type of shoe bottom embodying the invention;
Figs. 11 and 12 are perspective views of the bottom and top, respectively, of a combined sole and heel constructed in accordance with the invention;
Figs. 13 and 14 are sectional views on the lines i3-i3 and M-H, respectively, Fig. 10;
Fig. 15 is a perspective view oi another shoe embodying this invention;
Figs. 16 and 17 are vertical, sectional views through the forepart and heel part, respectively, of the shoe shown in Fig. 15; and
Fig. 18 is a fragmentary, vertical, sectional view showing features of another form of the invention.
Referring rst to Figs. 1 to 4, inclusive, the shoe there shown comprises an upper `2, an insole 3, and an outsole, which is indicated in general at 4. The upper may be of any suitable character such as fabric, leather, or combinations of these materials. As above indicated, the greater part of the weight of a shoe is in its bottom structure. In most shoes it is necessary to have a bottom of considerable thickness in order to prevent the foot from feeling too plainly the irregularities in the ground, to provide better heat insulation, and to avoid excessive flexibility in the shoe bottom. According to the present invention, these desirable characteristics are obtained, while still producing the necessary wearing qualities and avoiding excessive weight, by using in the bottom structure a high percentage of sisal fiber. In the particular shoe shown the insole 3 consists essentially of a layer of sisal ibers loosely matted together but heid in cooperative relationship to each other through the use of a limited quan-y tity of a waterproof binder. This may, for example, be rubber. or it may consist of some cellulose ester, such as cellulose acetate, dissolved in a suitable solvent. Or, binders may be dispensed with, and the body of iiber may be mechanically bound together as, for example, by superposing a flexible top sheet a, Fig. 1, on the layer of fibers, and stitching this and said layer together, preferably with a fabric bottom sheet.
The outsole, as shown in Fig. 3, is composed of an upper section c and a lower or tread layer d. The upper section consists of a body of sisal ber either made of ply structure or not, as desired, and containing a sumcient proportion of rubber, or other waterproof binder, to bond the fibers securely together' but Without materially decreasing the porosity or reducing the volume of the voids in this member. The top and bottom surfaces of this sisal fiber layer, however,
are suiciently coated with a highgrade gum covered with a binder strip 8 which is initially coated with a rubber and therefore bonds securely to the rubber content of the sisal fiber assembly.- The nature of this binder strip necessarily will be determined by the character of the shoe in which it is to be used. For some purposes it will simply be a strip of rubber compound. In other shoes, such for example as that shown in Fig. l, it is preferable to use a fabric binder of some such nature as that illustrated in Fig. 5, the .color and texture of which will contribute to the general design of the shoe. The tread layer d may be made of any suitable rubber composition which will give the desired wearing qualities. It also may be colored, embossed, or ornamented in any suitable manner. In making this shoe the usual procedure is to make and stitch together the parts of the upper'in the usual manner, and then to perform the shoe making operations on a last, the 'various parts of the bottom having previously been manufactured. Usually the insole 3 is first secured to the bottom of the last, its margins are coated with cement, and the upper is lasted over upon these margins in the same manner as in making rubber footwear of the orthodox types. Next a rubber welt 6 is cemented entirely around the lower margin of the insole 3, and a friction binder sheet 'l is cemented to the bottom of the insole, provided this strip has not been included in the insole: structure. In the latter event, it is coated with cement at this stage oi' the process. The sisal fiber assembly c now is properly registered with the edges of the shoe andl is laid upon the bottom of the insole and the overlasted margins of the upper, after which the tread layer d is similarly registered with and applied to the bottom of the section c. If the parts have been assembled while the rubber elements are in an unvulcanized condition, then the shoe will be subjected to vulcanization. n the other hand, if the parts when assembled are in a vulcanized or self-vulcanizing state, then the vulcanizing step may be eliminated. Usually the former practice is preferred. While the sisal section of the outsole may be made in various ways, the preferred method consists in working the long sisal fibers into the form of a layer or sheeted body having considerable thickness, say for example, three-eighths of an inch or a half inch. such a body is illustrated at Ill in Fig. 6. This operation can be performed by hand or in various kinds or ber working machinery designed for the purpose of manipulating fibers and presenting them in a sheeted or bat form. In such a, sheeted body the fibers are not arranged inany definite relationship to each other, but are disposed promiscuously, the fibers being so distributed, however, that when the mass is compressed a sheet or layer of substantially uniform thickness will be produced. In this connection it may be pointed out that while sisal is the preferred ber, hemp can also be used satisfactorily. The textile bers and others of a similar nature, however, are distinctly inferior. The sheeted stock produced in the manner. above described is next impregnated with a binder adapted to bond the fibers together permanently. lA flexible waterproof binder should be used for this purpose and the best material which I have been able to i'lnd is a rubber binder such as rubber latex, either vulcanized or unvulcanized. In some cases, however, other binders, such as those of an asphaltic nature, or those made from synthetic gums, resins, or balsams, may be employed. The impregnating step may be performed in any convenient manner as. for example, by running the sisal ber bat through the liquid binder and then through squeeze rolls to remove the surplus, after which the bat should be dried to evaporate the solvent or other dispersing agent used. If latex is used for this purpose in the ordinary concentrations, the bat will pick up approximately its own weight' of rubber. In other words, after the water or serum has been evaporated, the impregnated sheet will have gained approximately its own weight of dry rubber. The proportion of binder so`added to the bat can, however, be controlled by suitably varying the concentration of the impregnated bath.
The impregnating, squeezing, and drying operations above described compresses the bat so that its nal thickness may be perhaps one-quarter or one-half of that of the original bat. The material at this stage of the process is indicated at Il in Fig. 7. Usually it is desirable to apply a calendar coat of rubber to one side of the sheet ll, as shown at I2 in Fig. 8, and for most purposes a spreader coat I3 of rubber is subsequently applied to the uncoated side f the sheet.
In making insoles a sheet of the material which is to form the upper surface of the insole may then be combined with the layer shown in Fig. 8. Also,in these calendaring and spreader coating operations the layer is further consolidated to bring it down to the desired dimensions, the final thickness being so predetermined that the layer will have the necessary degree of mechanical strength, porosity and resistance to compression.
The sheeted layer of sisal fiber produced in the manner above described is a highlyporous, open, reticulated structure through which air flows very freely, the proportion of binder added to the original fiber being so limited-.that the fibers are united chiefly at their intersections with each other, but the interstitial spaces are not substantially reduced. In this connection it may be pointed out that in making the insole 3 the layer Il, as shown in Fig. 7, is sometimes used.
In making soles or heels several processes may be followed. For example, the' uncoated but impregnated layers l I may be completely filled with rubber and either vulcanized, or partially vulcanized, depending upon the subsequent shoe making processes. At any convenient stage in this procedure the plies may be secured together to produce soles and heels of the desired thickness as illustrated at 8 and 9 on the shoe shown in Fig. 9. Here the soles and heels are solid, but a high proportion of the rubber has been displaced by sisal ber and the presence of these fibers at the bottom or wearing surfaces of these members greatly reices the tendency of the rubber to slip on a wet surface.
According to the method usually preferred, the sisal layers Il are coated on one or -both sides and then the desired number of them are superposed, one on another, necessary to build up a structure of the required thickness for the heel or sole (both these elements being hereinafter included, where the context permits, in the term outsole). Sole and heel blanks may be cut out of such an assembly with the usual cutting dies, and the heel blanks may be applied to the heel ends oi' the sole blanks, as shown in Fig. 10,
the sole blank being indicated at Il and the heel blank at I5. These parts will be secured to each other by the rubber coating or coatings which they carry. Subsequently a tread layer I6 of a suitable rubber composition is applied to the outer Cil surface of this entire assembly and secured thereto by the inherent adhesiveness of these parts or by suitable rubber cement. Also, an edge covering or binding strip I1 of rubber preferably is applied to this whole assembly, this strip being cut to size and shaped preparatory to being applied, one edge f, Fig. 11, being registered with the inclined breast of the heel portion of the outsole and then the strip being extended around the heel and the forepart and the nal edge g abutted against the edge f. 'I'his binder overlaps both the sisal and the rubber plies and is folded over upon the upper surface of the sisal section I4, as clearly shown in Fig. 12.
'I'he outsole assembly produced in the manner just described is then ready to be applied to the bottom of such a shoe as that shown, for example, in both Figs. 9 and 15. The latter shoe is of the outing type, usually made with a fabric upper, and the upper and outsole are secured together partly by the union of the rubber constituents of the insole and outsole and partly through the medium of a welt strip I8 like that shown at 6 in Figs. 1 to 4. During the vulcanizing operation this welt bonds securely to or unites with the folded-over portion of the cover strip I1 on the upper surface of the outsole assembly and these two parts thus cooperate to form a continuous rubber member uniting the-tread ply I6 of rubber with-the upper of the shoe. Thus all the exposed surfaces of thesisal body are completely covered with rubber.
Sections of the shoe shown in Figt 15 are illustrated in Figs. 16 and 17, the upper being indicated at 2D and the insole at 2I. A sisal ller strip 22 may or may not be used, as desired.
In some cases it is preferable to run the tread strip I6 for the sole directly through the heel and then to mount the heel on top of this strip. Such an arrangement is illustrated in Fig. 18 where the sisal layer is shown at I4' and the tread layer of the sole at I6', this latter layer extending the entire length of the sole. T he heel includes a sisal section I', a tread section 23 of rubber, and an edge covering strip 24 also of rubber. In this arrangement, therefore, the sisal body I5 is completely enclosed at top, bottom and sides by rubber. Preferably a stiifer sheet of material I9, Figs. 10 and 14, loaded with rubber is placed at the bottom of the heel above the tread layers I5 or I6 where it serves to reinforce the tread layer.
It should be observed that in all these shoes .a` high proportion of the volume of the bottom structure consists of sisal ber. Consequently,
such a shoe may be made extremely light in weight while still having exceptionally good heatinsulating properties, ample resiliency to give the cushioning properties which are one of the important advantages of rubber shoes, and while body of air immediately under the foot, and a limited amount of interchange of this air naturally occurs in walking due to the resiliency of the sisal structure, better ventilation for the foot is produced than in ordinary shoes, and the tendency to burn the bottoms of the feet or to make them sweat excessively, is obviated. In fact, the shoe is extremely cool in hot weather. The shoe bottom also has the same wearing and waterproof characteristics as prior rubber soled shoes of corresponding types. vMoreover the sisal layers are of advantage in imparting to the sole added strength and the degree of stiness necessary to counteract the excessive exibility of the rubber. In addition, the expense of manufacture of a shoe of this character is less than that of shoes of corresponding grades made by the usual rubber shoe methods.
Having thus described my invention, what I desire to claim as new is:
1. A shoe comprising an upper, an insole, and a rubber tread member united thereto, a high percentage of the volume of said tread member consisting of a layer of sisal fibers loosely matted together but secured to each other by a exible binder, the proportions of said binderbeing so limited that said layer maintains a relatively thick body of air under the foot, and a rubber connection between lthe tread member and the shoe upper.
`2. A shoe comprising an upper, an insole, and an outsole united thereto, said outsole comprising a relatively thick layer of sisal fibers loosely matted together but secured to each other by a ilexible waterproof binder, the proportions of said binder being so limited l that said layer maintains a relatively thick body of air under the foot, a rubber tread layer permanently secured to said sisal layer, and a rubber connection between the tread layer and the shoe upper.
` 3. A shoe comprising an upper, an insole, and an outsole united thereto. said outsole comprising a relatively thick layer of sisal bers loosely matted together but secured to each other by a-ilexible binder, the proportions of said binder being so limited that said layer maintains a relatively thick body of air under the foot, a rubber tread layer permanently secured to said sisal layer, and a rubber strip covering the edge of said sisal layer and united with said rubber layer and connected to the shoe upper.
4. A shoe comprising an upper, an insole, and an outsole united thereto, said outsole comprising a relatively thick layer of sisal iibers loosely matted together but secured to each other by a ilexible waterproof binder, the proportions of said binder being so limited that said layer maintains a relatively thick body of air under the foot, a rubber tread layer permanently secured to said sisal layer, a rubber strip covering the edge o! said sisal layer -and united with said rubber layer, and a rubber welt strip connecting said edge covering strip with the upper o! the shoe.
ERNEST W. DUNBAR.