US3416244A - Shoe manufacture - Google Patents

Description

Dec. 17, 1968 M. R. RADCLIFFE ETAL. 3,416,244.

SHOE MANUFACTURE Filed Feb.` .18, 1964 [raven LO 11s /V/lzvon R. Radcliffe William Tabr'off United States Patent O 3,416,244 SHOE MANUFACTURE Milton R. Radcliffe, Marblehead, and William Tabrotf, Peabody, Mass., assignors to United Shoe Machinery Corporation, Flemington, NJ., Boston, Mass., a corporation of New Jersey Filed Feb. 18, 1964, Ser. No. 345,773 15 Claims. (Cl. 36--30) The present invention relates to shoe manufacture and more specifically to shoe bottom filling.

In Shoemaking, particularly welt and similarly constructed shoes, an upper is pulled over a last and attached by its lasting margin to an insole previously positioned on the last. This causes a cavity to be formed which is defined as to the bottom by the insole and peripherally by the inner edge of the lasting margin or by the insole rib. In order then to lay on an outsole properly it becomes necessary to fill or level this cavity. The usual practice is to do so with what is referred to as a shoe bottom filler, and, then following that the outsole is laid.

Shoe bottom filling may be effected in various ways. In one practice a pre-cut insert is used. More common, however, is the use of mastic fillers. These are introduced into the cavity in fiuid or workable state and set up in situ to a solid state. In the solid state, that is in set up or stiffened condition the fillers are preferably flexible and resilient in nature.

In theory at least the practice of using a mastic filler allows the attainment of better or more complete filling or to state it again better conformation between the filler and the cavity. It is the mastic type filler with which the present invention is particularly concerned.

Present mastic shoe bottom fillers are most commonly asphalt or other resin and cork mixtures. To place them in a fiuid or workable state they are heated or solvated using a common, volatile organic solvent.

Although the mastic fillers presently known contribute advantages to the shoemaking art, they have certain shortcomings. Perhaps the most serious of these involves shrinkage on setting. This is particularly troublesome. Aggravating this situation further is the fact that not only is it difficult to arrive at a bottom filler which completely fills a shoe bottom cavity on setting, but most shoemakers dictate that the filling should be carried out to the extent that it contributes a convex configuration to the outsole of a finished shoe. This is commonly referred to as a crown or crowning. It is in effect over-filling the cavity. Filling to that extent, with present mastic fillers, can interfere without sole laying and attaching. Other difficulties with mastic fillers that are presently known include their proneness to break down, crack, fragment or disintegrate and fioat. The latter cited difficulties reliect that it is desirable to unitize the various shoe bottom parts, to wit: insole, outsole, as well as the shank which is commonly included, and the filler.

It is an object of this invention to provide a shoe bottom filler which may be introduced into a shoe bottom cavity in fiuid form -where it sets conveniently to a solid state, and in the latter state has excellent conformation with the shoe bottom cavity.

It is another object of this invenion to provide a shoe bottom filler which contributes to convenience in obtaining crowning in an outsole laid on a shoe in which the filler is included.

It is another object of this invention to provide a shoe bottom filler which on setting serves to unitize the various shoe bottom components, to wit: insole, outsole and shank, together with the filler.

It is another object to :provide an improved method for filling a shoe bottom cavity.

3,416,244 Patented Dec. 17, 1968 ice These and other objects are obtained in a shoe bottom filler which is initially in fiuid state being based on a moisture-curable isocyanate-containing prepolymer. In fiuid state the subject filler may be introduced into a shoe bottom cavity where with exposure to moisture it sets up to a solid state conforming with or filling or leveling the cavity to a predetermined extent.

In order to illustrate the present invention the following drawings are included in which:

FIG. l is a bottom plan view of a lasted, shoe upper assembly shown prior to filling the shoe bottom cavity;

FIG. 2 is a bottom plan view of a shoe upper assembly shown after the shoe bottom cavity has been filled;

FIG. 3 is a section along the line III- III of FIG. 2; and

FIG. 4 is a transverse sectional view of a finished shoe assembly of Goodyear welt construction.

An embodiment of the present invention will now be described with reference to the drawings in which a shoe upper 10 is shown pulled over a last 12, see FIG. 3. Initially insole 14 is positioned on the last 12 by means of tacks 16. Insole 14 includes a rib 18. A shank piece 20 is prelimnarily stationed on the insole 14 by staples 21 which pass through holes 22 located toward the ends of the shank piece 20. Referring to FIG. 1, the lasting margin 10a is attached to an insole 14 in a convenient manner as by adhesive attachment or the like. The lasting edge 10b which is the inward edge of the lasting margin 10a may also extend upwardly of the same and is shown trimmed to approximately the same height as that of the rib 18. A shoe bottom cavity 23 is formed, being defined as to its bottom by the insole 14 and peripherally by the rib 18. In the case of a fiat-lasted shoe, the cavity 23 would be defined peripherally by the edge 10b of the lasting margin 10a.

A welt 24 is included in the assembly. This is attached by stitching 25 to the rib 18, see specifically FIGS. 3 and 4.

Continuing with reference to FIG. 2, the cavtiy 23 is caused to be at least partially filled by a predetermined amount of the mastic ller 26 of this invention. As shown, mastic filler 26 is introduced into the cavity 23 in fluid form from a nozzle 28 of a mastic dispensing applicator, not shown, which maintains the mastic filler in essentially moisture-free condition prior to dispensing or extruding the same. Following that, the mastic filler 26 may be distributed throughout the cavity 23 by a spreading tool 30, or, as otherwise desired. While the mastic filler 26 may be distributed throughout the entire area of cavity 23 it is generally restricted to the forward end and partially in the shank area of cavity 23 as indicated in FIG. 2. This is sufficient to facilitate outsole laying and obtain the desired unification of various components.

The mastic filler 26 is of foamable or expandable nature. This characteristic serves to cut down Weight. In addition however, the mastic filler 26, when it assumes a foamed or expanded solid state is liexible and resilient, and if desired, may be compressible in order for it to provide a cushioning effect when it is in a final solidified form.

Turning to FIG. 4, after the mastic Afiller 26 is introduced into the cavity 23 an outsole 32 may be laid on and permanently attached vby stitching 34. Other shoemaking loperations in the nature of finishing usually practiced may be carried out as desired.

As previously indicated, the mastic filler 26- sets up or is cured in situ to a solid state within the cavity 23. In solid state the mastic filler 26 has a cellular or expanded structure and exhibits a fiexible, resilient nature.

A crown effect may be obtained in the outsole 32 by tak-` ing advantage of the fact that the mastic filler 26 expands with curing.

Following the introduction of mastic iiller 26 into the cavity 23v it is not necessary to allow hiatus in time before laying on outsole32. Rather, the preferred practice is to carry out the outsole laying operation as soon as possible following tilling the cavity 23 with mastic iller 26.

As can be noted from FIG. 4, on setting, the iiller 26 not only serves to lill the cavity 23 but also serves to unitize the various shoe parts, to wit, the outsole 32, shank 20, insole 14, etc. into a consolidated, yet flexible whole.

The mastic filler which can be used in practice of the present invention is an isocyanate-containing polymer. In its initial, Huid or workable state it is a prepolymer which is moisture-curable. Moisture-curable indicates that the prepolymer, and more specifically the free isocyanate groups contained in the same, have the capacity to react with water, either in vapor or liquid state to effect curing to an expanded, flexible and resilient solid state. The moisture required for reaction may be provided by the atmosphere, that is it may be ambient in nature, or it may be added from a separate source. The capacity to be moisture-cured by means of ambient moisture represents a convenience and so is desirable from a Shoemaking consideration.

Prepolymers which may be used are those based on polyols. These include lin addition to polyhydric alcohols, the polyester polyols and polyether polyols. Principally, the polyesters and polyether polyols are used. Examples of the polyester polyols are those based on adipic acid, dimer acid, phthalic acids, phthalic acid anhydrides, castor oil, etc. while the polyethers are exemplied by those based on glycerine, trimethylol propane, sorbitol and pentaerythritol to which polypropylene oxide may be added to increase the molecular weight. Examples of the polyhydric alcohols which may be used include those which are chain extended such as the polyhydric polypropylene oxide, polyethylene oxide, etc. In order that the prepolymers obtained have desirable exibility or crackability it is recommended that the polyol used have a molecular weight in the range 500 to 2500 per hydroxyl group present on the polyol.

In producing the prepolymers, the polyols are reacted with an excess of isocyanate to provide moisture-curable isocyanate-containing prepolymers having an excess of free yor unreacted isocyanate groups. The excess isocyanate groups'then contained in the prepolymer are then capable of reacting with moisture causing the prepolymer to cure to an expanded, ilexible, resilient solid state. In order that the expanding-curing reaction be effectively orestalled until filling itself is carried out it is prescribed that the polyols for reaction with the polyisocyanate be in at least essentially moisture-free condition and that also the polyisocyanate-polyol reaction be carried out under at least essentially moisture-free conditions.

The polyols, for use in the prepolymer may be a diol, triol, and other polyhydrics in addition to blends of the same. When reacted with a polyisocyanate a prepolymer may be provided having an excess of isocyanate groups. The excess is free isocyanate groups desired on the prepolymer is preferably greater than two free isocyanate groups on a mol ratio basis in order that a resilient, flexible, solid ller be obtained as a result of moisturecuring. With less than the indicated amount of free isocyanate groups present in the prepolymer the prepolyrner does cure ybut in doing so does not provide a solid filler which is iiexible, resilient and coalesced into a unitary -form of the nature of rubber, such as is preferred in practice of this invention. In the event that the polyol is a diol, a triisocyanate such as polymethylene polyphenyl isocyanate (PA-PI) may be used to obtain a prepolyrner having this desired excess of isocyanate groups. If the polyol is .a triol, a diisocyanate such as toluene diisocyanate (TDI), etc. may be used to obtain this result.

The isocyanate containing prepolymers are expandable with moisture-curing. The moisture, that is the water, when made available reacts with the isocyanate groups to provide carbon dioxide which causes foaming or expansion together with curing. Auxiliary blowing agents may be added if desired, but are no-t necessary. These would include the various uorocarbons generally used for this purpose. In addition various catalysts, stabilizers such as moisture yscavengers and the like may be included.

The prepolymers for .use in this invention may include extenders such as the petroleum derived, high aromatic content hydrocarbon oils, of the type used as rubber extenders (examples are the Dutrexes which is a trademark designation of the Shell Oil Company), also various natural oil derived extenders such as tall oil, cottonseed oil, corn oil and the like may also be used for a similar purpose. Fillers such as pitch, bitumins, ashphalts, synthetic polymers such as polyvinyl chloride, polyestrene, etc. may also be used to extend the prepolymers. Other llers which may be included are ground cork, clay, sulfur, glass bers, wood pulp, foam glass, gypsum,l also alumina silicates, alumina hydroxides, etc. It is proposed that with respect to extenders and fillers as well as other additives to the prepolymer that they be free of moisture and non-reactant in nature with the free isocyanate groups contained on the prepolymer. The various lillers and extenders may be included in the prepolymer, on a weight ratio of 1:4 to 4:1 with good results.

The following examples are included for the purpose of further illustrating the invention.

EXAMPLE I Prepolymer Preparation A-Formulaton Part l: Ppw. Polypropylene Glycol (3000 mol wt.) 600 Dutrex 739 (aromatic petroleum fraction) 1200 Sulfur 3600 Part 2:

PAPI (polymethylene polyphenyl isocyanate) 160 N,N tetramethyl butane diamine 1.6

Part l is dehydrated under vacuum of 30 mm. Hg and C. for a period of two hours in a Baker-Perkins dough mixer. The ingredients of Part 2 are then added to the mixer and while maintaining the vacuum, reaction is allowed to proceed for a period of two hours. The reaction product is obtained as a heavy, pasty yet spreadable or workable mixture. It is removed from the mixer and packed into a tive gallon metal container under vacuum conditions. The reaction product is noted to have a doughy consistency.

Prepolymer Preparation ,fl-Formulation Part l: Ppw. Polypropylene glycol (3000 mol wt.) 600 Dutrex 795 (aromatic petroleum fraction) 1200 Molecular Sieve S-A powder (synthetic crystalline alumina-silicate) 20 PAPI Part 2:

Sulfur (Rubber Makers) 3600 Ground cork 340 The individual ingredients of both Parts l and 2, exclusive of the polyisocyanate, are dehydrated under 30 mm. Hg vacuum and 80 C. in a Baker-Perkins dough mixer. Part 1 ingredients are then tumbled for two hours in the mixer, again under 30 mm. Hg and 80 C. Thereafter, one half of the sulfur is added and after five minutes of tumbling the remainder of the sulfur is added. Again afteriive minutes tumbling time the cork is added and tumbling continued for another tive minute period. The product of the mixer is fluid in nature and is discharged and directed into a ve gallon container quickly. The container is rapidly closed With minimum air space.

Prepolymler Preparation C-Formulation Part 1: Ppw. Propylene oxide runout of hexane triol (3300 mol wt.) 240 Toluene diisocyanate 40 Tall oil 1640 Part 2 Sulfur 1000 Exclusive of the toluene diisocyanate, the ingredients of both Parts l and 2 are dehydrated under 30 mm. Hg vacuum at 80 C. for a period of two hours. The ingredients of Part 1 are then charged separately into the mixer and tumbled for two hours under the conditions specified above for dehydrating. Thereafter, half the sulfur of Part 2 is added and tumbling continued for 10 minutes. The remainder of the sulfur of Part 2 is added and tumbling continued for another 30 minutes. The prepolymer is removed from the mixer and transferred to a ve gallon container which is then tightly closed with a minimum of air space retained in the same.

Shoe cavity filling D Immediately prior to utilization each of the prepolymer fillers prepared according to paragraphs A-C above, are charged into a Graco Powero Extrusion Unit (Model 225-95/designed for use with a five gallon drum). This involves removing the covers from the containers storing the 'prepolymer iillers and introducing into each the intake of the Extrusion unit. The intake is fitted with a horizontally flaring O-ring gasket which fits tightly at its periphery with the interior sides of the storing container (v'e gallon).

The Extrusion unit is used to provide each of the shoe bottom cavities of a number of mens shoes, size 81/2, leather upper assemblies which include metal shantk pieces and are supported on lasts, with 30 gram charges of the prepolymer llers. The filler charge is actually deposited in the form of a ribbon approximately one inch wide and a quarter inch thick at the forward or toe end of the cavity and distributed back part way through the shank area. Distribution is facilitated by means of a spatula.

After filling, leather outsoles are immediately laid on the upper assemblies by cement spotting, and following that, the assemblies are placed in a soling press and outsole stitching is then carried out. The shoes are then finished in the usual fashion and the lasts removed. At this time it may be noted that the outsoles are crowned or to state it dicerently have a distinct convex shape.

4Shoes produced as above are then wear-tested for an extended period. Wet and dry iexing tests are also carried out on them. The shoes are then slit through to show their structures in cross-section. At this point it is noted that in each of the shoes the ller has a foamed or celled structure. The filler is resilient and flexible; and does not show cracking, fragmentation or disintegration of any type. In addition each of the shoes shows good unitization or bonding between the outsoles, Shanks, and insoles through the fillers. y

It will thus be seen that the objects set forth above among those made apparent from the preceding description, are eiiiciently obtained and, since certain changes may be made in carrying out the above method and in the shoe assembly set forth Without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. A method for bottom filling a shoe which comprises (a) at least partially filling a bottom cavity of a shoe assembly with a mastic iiller which comprises moisturecurable isocyanate-containing prepolymer in fluid form, (b) laying an outsole on the shoe assembly and (c) allowing the prepolymer to set to a solid state by exposure to moisture.

2. A method according to claim 1 wherein the prepolymer contains greater than two free isocyanate groups in mol ratio.

3. A method according to claim 1 wherein the prepolymer comprises a triisocyanate and a diol.

4. A method according to claim 1 wherein the prepolymer comprises a diisocyanate and a triol.

5. A method according to claim 1 wherein the isocyanate-containing prepolymer is extended with a hydrocarbon oil having a high aromatic content.

6. A method according to claim 1 wherein the prepolymer is combined with a solid iiller while in uid form.

7. A method according to claim 6 wherein the solid ller is sulfur.

8. A method according to claim 6 wherein the solid ller is ground cork.

9. A shoe assembly having a bottom. cavity lled with a mastic filler in expanded solid state comprising polyurethane obtained by in situ curing a `quantity of a moisture-curable isocyanate-containing prepolymer located within said bottom cavity and having an outsole laid on the same prior to said curing in situ.

10. A shoe assembly according to claim 9 wherein the prepolymer comprises a triisocyanate and a diol.

11. A shoe assembly according to claim 9 wherein the prepolymer-comprises a diisocyanate and a triol.

12. A shoe assembly according to claim 9 wherein the prepolymer is extended by a hydrocarbon oil having a high aromatic content.

13. A shoe assembly according to claim 9 wherein the mastic ller includes a solid filler.

14. A shoeassembly according to claim 13 wherein the solid filler is sulfur.

15. A shoe assembly according to claim 13 wherein the solid ller is ground cork.

References Cited UNITED STATES PATENTS 1,909,089 5/1933 Beckwith 12-'148 X 2,096,511 10/1937 Gordon 12-148 X 2,905,582 9/1959 Coleman et al. 154-139 3,061,475 10/1962 Wallace 117-155 3,116,501 1/1964 Markevitch 36-14 X OTHER REFERENCES Dombrow, B. A.; Polyurethanes, Rheinhold Publishing Corp., N.Y., 1957, pp. 24 and 25.

PATRICK D. LAWSON, Primary Examiner. H. H. HUNTER, Assistant Examiner.

U.S. C1. X.R.

Claims (1)

1. 9. A SHOE ASSEMBLY HAVING A BOTTOM CAVITY FILLED WITH A MASTIC FILLER IN EXPANDED SOLID STATE COMPRISING POLYURETHANE OBTAINED BY IN SITU CURING A QUANTITY OF A MOISTURE-CURABLE ISOCYANATE-CONTAINING PREPOLYMER LOCATED WITHIN SAID BOTTOM CAVITY AND HAVING AN OUTSOLE LAID ON THE SAME PRIOR TO SAID CURING IN SITU.

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