US1968668A - Shoe bottom filling material and method of making the same - Google Patents

Description

Patented July 31, 1934 PATENT OFFICE snon BOTTOM FILLING MATERIAL AND METHOD or MAKING THE SAME Richard .Almy, Lancaster, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania v i No Drawing. Application May 5, 1932,

' Serial N0. 609,503

9 Claims.

This invention relates to shoe bottom filling material and more particularly to abottom filling material which can be spread into the shoe cavity in a cold condition as contrasted with bottom ,5 fillers which depend upon a thermoplastic binder which must be rendered workable by the application of heat or heat and moisture.

The most commonly used shoe filler of the hot or thermoplastic type consists of a filler such as cork particles held together with a thermoplastic binder such as wax tailings. The mass is formed into loaves at the manufactory and supplied-to the shoe trade in that shape. The material is usually broken into small pieces and placed in heating devices which render-the binder plastic and permit application of the filler to the shoe cavity by means of a heated spreading tool. Upon cooling, the binder hardens and returns to its original condition.

The hot fillers have never been entirely satisfactcryfrom a production nor a quality standpoint. The temperature of the heaters must be carefully watched or the filler will char; the mass is of a sticky, messy nature and requires careful manipulation in order to prevent smearing of the shoe upper upon handling by the filler operator. Thehot fillers due to their thermoplasticity are readily deformed and take a. permanent set when deformed by pressure. On account of the melting nature of the binder, the material has a tendency to bunch and form ridges in, the innersole around that portion which is engaged by the ball of the foot. There has always been the problem of staining. This staining is particu larly prevalent in womens shoes where a high grade, thin flexible outersole is used. This somewhat porous and readily absorbs the binder of the filler, carrying it throughout the sole :and causing discoloration of the outer surface of the outsole. There has also been considerable diffi: culty encountered due to the fact that the binder oozes through the tack holes in the inner sole under pressure such as at the leveling opera-. tion. The presence of the thermoplastic binder in the inner face of the innersole is objectionable from many standpoints. Its presence is readily detected. Its presence often results in discoloration of the stockings of the wearer. This has been one of the major problems facing the shoe filler to manufacturer. 7

Due to the shortcomings of the thermoplastic fillers, the shoe manufacturers have looked for other types of fillers. Fillers capable of application in the cold have been tried. These fillers {53 usually set up by the evaporation of a solvent and can therefore be applied in the cold state and will set up by exposure to the air or by the action of moderate heat and no expensive conditioning equipment is required for their use. The cold fillers at present on the market, however, have not overcome the problems which were inherent in the hot fillers and at the same time certain new problems have come into play.

A. mixture of comminuted soft filling material and dissolved rubber has been used to some extent as a cold filler. This mixture usually is prepared at the shoe factory due to the unstable nature of the binder. There is considerable shinkage upon evaporation of the rubber solvent and as a consequence the entire cavity is not filled. The binder does not form a tough, tenacious mass and the filler gradually disintegrates upon flexing of the shoe. The material is relatively slow drying and production is curtailed while the filler is drying.

It has also been proposed to use a mixture of cork held together with a water solution of gum or other adhesive. This material is relatively slow-drying and shrinks materially, so that a relatively wide channel exists between the filler and the insole lip upon drying of the filler. This of course is objectionable. The material being water soluble is not extremely waterproof and-takes a relatively long time to set. The gum binder is somewhat brittleand the filler will crack upon flexing.

More recently a cold filler has been introduced which consists mainly of mineral fillers held together with a dispersed rubber binder. While this material is fairly satisfactory so far as bond and flexibility are concerned, the shrinkage is great and the setting progresses slowly. This filler is quite heavy and expensive. It tends to take a permanent set under compression and is not resilient.

In the manufacture of shoes, the innersole is nailed to the last usually with five or six nails; three of which commonly are placed in the fore part of the innersole. Prior to the laying of the outsole, the nails which hold the innersole to the last are removed and the filler placed in the space formed by the raised lip or channel on the innersole. The outsole is subsequently applied. If the outsole is secured by stitching or nailing, the sole is leveled. This operation consists essentially in applying high pressure upon the sole by means of rolls which contour the shoe bottom to the desired form. When thermoplastic fillers are used, this pressure forces the binder of the filler through the nail or tack holes in the innersole and causes staining.

In the so-called cemented shoes, the outsole is secured by means of a suitable adhesive. The component parts are first covered with adhesive and pressed together under considerable pressure. This pressure frequently forces the binder of the filler through the tack holes in the innersole as Well as through the thin fiexible outsoles used in womens shoes.

The methods of forming shoes and the problems incident thereto are so well known in this art that a detailed outline of the various processes and defects is not necessary. I will, however, outline some of the desired physical characteristics of a bottom filling material:

1. It should be of such character that it can be applied without the aid of heat or other processing at the shoe factory so that a stable product is obtained upon completion of the shoe and expensive processing is eliminated.

2. It should be of an unctuous, slippery nature so that a smooth, even surface can be quickly and conveniently obtained.

3. It should take a definite set quite rapidly so as to permit further processing without delay but it should not take a permanent set until after the shoe has been finally formed because the sole must be contoured during the leveling operation and the filling must conform generally to this shape. The filling should take an initial set in 4 or 5 minutes but should not become permanent for at least 10 or 12 hours.

l. It should contain a binder which produces a tough, resilient mass upon final setting.

5. It should contain a major portion by volume of a light filler such as cork in order that it will possess a springy, heat insulating character which resists permanent deformation under pressure but which will quite readily deform under pressure and reexpand to its original shape. a

6. It should contain a'binder which holds the particles together and prevents crumbling or bunching. The binder should preferably be relatively stable at normal temperature so as to maintain its shape under warm, moist conditions of usage.

7. It should be flexible after the permanent setting has taken place so that the filler will not crack upon fiexing of the sole. 7

8. The material should not shrink to any great extent in order that the shoe cavity be entirely filled after setting of the binder.

9. It should contain a binder which firmly and tenaciously secures the individual filler particles one to the other and forms a homogeneous, tough, flexible, resilient mass. 7

10. It should preferably be waterproof in order to maintain its shape and characteristics when exposed to moisture. I

I have found that a shoe filler having the desired characteristics outlined above can be obtained with the use of an oil-resin gel binder which has been modified with a suitable material which toughens the binder and produces a stable and resilient binding agent.

As a base for the binder of my new shoe filler, I prefer to use a siccative oil-resin gel. Linseed, soya bean, China-wood and menhaden oils are examples of siccative oils suitable for use in my binder. Other drying or semi-drying oils or mixtures thereof may be used if desired.

The gel may be produced in any desired manner such for example as by heating or oxidizing. The oil may be mechanically oxidized in the presence of a resin in the usual heated heaters, such as the Bedford machine'or it may be oxidized by the scrim process wherein the oil is trickled over hanging sheets of scrim cloth in a heated chamber until a sufiiciently thick layer of gelled oil is obtained. The resin may be then incorporated with the oil gel so formed by the use of a suitably heated mixing kettle.

I have found that a thoroughly oxidized oilresin gel produced by mechanically oxidizing a mixture of 90 parts menhaden oil, 10 parts linseed oil and 33 parts rosin forms a satisfactory base for my binder; all parts being given by weight.

This mechanically oxidized oil and rosin is discharged from the oxidizing kettle and allowed to cool. The gel produced is relatively stiff, tough, flexible, and. coherent. The gel is out into pieces convenient for handling and placed in a suitable mixing machine and suitable solvents for the gel are added thereto in order to form a jellylike mass which can be readily intermixed with the fillers and which will coat the filler particles. For example, with a batch of gelled oil and rosin weighing about 400 pounds, a mixed solvent consisting of about 245 pounds toluol which is an active solvent for the gel, 245 pounds denatured alcohol which is a substantially inactive solvent for the gel and 19 pounds turpentine will reduce the stiff gel to a relatively viscous, jellylike mass in about 5 or 6 hours. The effect of the above solvents on the oil-rosin gel is to cause the gel to swell by imbibition of the solvent. Only sufficient solvent is used and the processing time so controlled that the oil-rosin gel is swelled but not completely dissolved, thus forming the jelly-like mass. If desired, the material may be warmed to about 100 to 110 Bin order to facilitate reduction. The action of the various solvents in the production of my filler will be more fully described hereinafter.

The toughening agent may consist of nitrocellulose, partially denitrated gun cotton or other cellulose esters. I prefer to use dissolved film scrap such as sheeted cellulose nitrate or cellulose acetate, which is relatively cheap and readily available.

Cellulose nitrate film scrap when dissolved forms a very desirable toughening agent. This may be readily produced by dissolving 17 parts by weight of film scrap in 83 parts by weight of ethyl acetate. I prefer to use just sufiicient solvent to produce a jelly-like viscous mass by swelling. If too much solvent is used there is a tendency for the solvent to break down the oilresin gel upon mixing the toughening agent with the binder and the amount of shrinkage of the final product is dependent to some extent upon the amount of solvent used.

The toughening agent may be incorporated into the oil-resin gel base up to about parts by weight of the total batch. The amount of toughening agent added will depend to some extent upon the hardness desired in the final filler and the kind of bulking filler used. I have found that a mixture of parts by weight of swollen oilresin binder and 25 parts by weight of toughening agent produces a satisfactory binder for a cork filling material. Stated in terms of actual binder and toughening constituents, less solvents, the mixture would consist of 88.5 parts by weight of oil-resin gel and 11.5 parts by weight of toughening agent. The proportions can be varied to a considerable extent in order to meet the requirements of the shoe manufacturer.

The oil-resin binder and the toughening agent are thoroughly intermixed to produce a homogeneous mass. 'Ihebinde'r thus formed isthen mixed with the desired bulking fillers.

A highly satisfactory commercial shoe filler having the desired characteristics above outlined can be produced by mixing a large volume of cork granules with a minor amount of my binder. For example, an easily worked filler may be produced by mixing in any suitable mixing machine a batch consisting of 25 parts by weight of 20 to 30 mesh cork and 150 parts byweight of the toughened binding agent above described. The proportion of cork to binder and solvent is about 3 parts of cork to 1 part of binder and solvent by volume or stated in terms of actual binder and toughening constituents, less solvents, about 8 or 9 parts of cork to 1 part of binder by volume.

The size of the cork granules can be" varied considerably. A finer granulation of cork will produce a somewhat less resilient filling material, however. Leather dust, wood flour or other filling materials may be used in place of the cork. I prefer to use cork because of itssoft, springy, resilient nature and also because of its heat insulating properties. A 'more dense filler will result if mineral filling material is used.

In the specific example given above, just sufiie oient solvent is used to produce a viscous oil-resin gel. The gel holds the solventsand permits more I rapid setting than if there were an excess of solvent which would be absorbed by the filling material. It is not essential that a mixed solvent such as toluol and alcohol be used. Alcohol has a lower boiling point than toluol and a more rapidly setting filler is produced if alcohol is used. A suflicient amount of toluol may be used as the sovent, however, if a quick setting composition is not essential. In place of toluol, naphtha or solvent naphtha may be substituted and in place of denatured alcohol, any low-boiling solvent may be used such as carbon tetrachloride or ethylene dichloride. I prefer to use alcohol because of its ,cheapness. In the specific example, 19 parts by weight of turpentine has been used. This serves primarily as a deodorant to kill the odor of the menhaden oil. In place of turpentine any suitable deodorant may be used, for example, the oil of Wintergreen or Sassafras or the deodorant may be entirely eliminated if desired.

A swelled oil-resin gel contains a large proportion of solid material and therefore there is no material shrinkage upon evaporation of the dissolving agents. The swelled oil-resin gel, however, sets up rather slowly and since a rapid setting material is desired, I prefer to use a quick setting toughening agent in the form of a jelly-like viscous mass. A swelled cellulose ester toughening agent is ideal for this purpose since it produces a tough, tenacious binder and sets up quite rapidly due to the low-boiling solvent employed. There is, however, a relatively small amount of solid matter as compared with volatile matter in this swelled cellulose ester and for that reason it should be incorporated into the oil-resin gel binder in such proportion that shrinking is maintained at a minimum. In the example given above wherein the ratio of cork to binder and solvent is 3 to 1 and the ratio of swollen oil-resin gel binder to toughening agent is 3 to 1, there is no apparent shrinkage. If the ratio of filler to binder is decreased, the ratio of toughening agent to oilresin gel should also be decreased if shrinking is to be kept at a minimum.

I believe there is some interaction between the oil-resin gel and the cellulose ester which actszas a stabilizer of the oil-resin gel. It is well known that oil-resin gels harden considerably upon aging due to oxidation. I do not limit myself to the theories thus expressed but at any rate, the shoe filler is permanently elastic and flexible.

.In place of ethyl acetate, I may use any lowboiling solvent or mixture of solvents such as acetone, diacetone alcohol for dissolving the cellulose.

Iumy preferred'embodiment, the rosin, which is added to the oil prior to oxidizing, acts as a Ipeptizer and prevents heat thickening prior to complete oxidation. The rosin may be eliminated and a gelled oil will be produced. The gel will not be thoroughly oxidized, however, and will not possess the adhesive qualities of an oxidized oil-rosin mixture. In place of rosin in my preferred oil gel, I may employ any of the well known anti-coagulants possessing adhesive properties, such for example as Kauri gum or ester gum which have been used to a considerable extent in the linoleum industry.

When a .mechanically oxidized oil-resin gel is used, the solvents may be added to the oilresin gel in the oxidizer after the oil-resin gel has cooled sufficiently to prevent any undue volatilization of the solvent. I have successfully introduced the solvents into the oxidizer after the mass has cooled to about 170 F. Mixing is continued until the proper swelling has taken place.

Oil-resin gels of the type employed in my binder are readily soluble in solvents such as toluol, alcohols, solvent naphtha or combinations thereof and care must be exercised in the swelling of the oil-resin gel or a thin, nonviscous, relatively liquid material will result upon continued mechanical working. By the term readily soluble I mean that the oil-resin gel will dissolve by mere intermixing with the solvent or solvents and does not require autoclaving or other pressure equipment, such as is required to dissolve some oil gels.

The completed filler is usually placed in suitable air-tight cans or drums for shipment to the shoe manufacturer. The workman simply removes a small portion from the container, (usually sufficient for about twenty minutes work) and places this in a small bowl or container on the work-bench. He then fills the shoes with the aid of a spatula or other spreading tool. No heating or processing of any sort is required after the material reaches the shoe manufacturer.

The material is slippery and is easily applied. It takes a set within a few minutes due to the low boiling solvents. The material upon final setting is tough, resilient and does not perma nently deform under pressure. There is little 135 or no shrinkage due to the minor amount of volatile constituents compared with the solids. The binder holds the filler particles tenaciously and prevents crumbling or bunching and at the same time produces a flexible mass. 140

By the term siccative oil I wish to include both drying and semi-drying oils.

While I have described certain specific preferred embodiments of my invention, it will be understood that the invention is not limited to 14% the specific examples but may be otherwise embodied and practiced within the scope of the following claims.

I claim:

l. A cold spreadable shoe filler composition 150 consisting of a mixture of comminuted resilient substantially non-absorbent filler, a swelled siccative oil-resin gel binder, and sufficient quick drying solution of a cellulose ester toughening agent to impart a rapid initial set but insuffie cient tovimpart noticeable shrinkage, made in accordance with the method of claim.5.

2. A cold spreadable shoe filler composition comprising a major portion by volume of a comminuted filler and a viscous jelly-like binder including a homogeneous mixture of asiccative oil-resin gel swelled by imbibition of an organic solvent in which said oil-resin gel is readily soluble, a minor amount of cellulose ester, and suliicient low-boiling solvent to swell the cellulose ester to a jelly-like consistency, said binder coating said comminuted filler without impregnation.

3. A cold spreadable shoe filler composition comprising a major portion by volume of comminuted cork and a viscous jelly-like binder including a homogeneous mixture of a siccative oil-resin gel swelled by imbibition of an organic solvent in which said oil-resin gel is readily soluble and a quick setting solvent swelled cellulose ester toughening agent of a jelly-like consistency, the quantity of said swelled siccative oilrosin gel exceeding the quantity of toughening agent and inhibiting shrinkage during the setting of the composition.

a. A cold spreadable shoe filler composition comprising a majorportion by volume of a comminuted filler and a viscous jelly-like binder coating said filler and including a mixture of siccative oil-resin gel swelled by imbibition of an organic solvent in which said oil-resin gel is readily soluble and a quick setting cellulose ester toughening agent in the form of a viscous gel, the ratio of filler to binder being substantially the same as the ratio of swelled siccative oil-resin gel to cellulose ester gel.

5. In the method of making a cold spreadable shoe filler composition, the steps consisting in forming a siccative oil-resin gel, swelling said gel by imbibition of solvent to form a jelly-like mass, forming a cellulose ester gel, mixing the gels to form a homogeneous viscous jelly-like mixture and adding a comminuted filler material to said gel mixture.

6. In the method of making a cold spreadable shoe filler composition, the steps consisting in forming a stiii oxidized gel of a siccative oilrosin mixture, swelling said gel by imbibition of a solvent until a jelly-like mass is obtained, forming a cellulose ester toughening agent by soaking said cellulose ester in sufficient low-boiling solvent to form a swelled gel of a jelly-like consistency, mixing the gels to form a viscous mixture and adding comminuted cork to said mixture.

7. In the method of making a cold spreadable shoe filler composition, the steps consisting in forming a siccative oil-adhesive resin gel, swelling said gel by imbibition of a mixture of active and inactive organic solvents to form a jelly-like mass, forming a cellulose ester gel, mixing substantially three parts of said oil gel with one part of said cellulose ester gel to form a homogeneous viscous jelly-like mixture and adding substantially three parts by volume of commnuted cork to one part by volume of said mixture and mixing the mass to form a tenacious, resilient filling material possessing a rapid initial set and a delayed permanent set.

8. A cold spreadable shoe filler composition comprising a major portion by volume of comminuted cork as a base and a binder for said base including a jelly-like mixture of a siccative oilresin gel swelled by imbibition of an organic solvent in which said oil-resin gel is readily soluble and a cellulose nitrate toughening agent of jelly-like consistency.

9. A cold spreadable shoe filler composition comprising a mixture of comminuted cork and a binder in the form of a jelly-like mixture and including an oxidized siccative oil-resin gel swelled by imbibition of a relatively high boiling organic solvent in which said oil-resin gel is readily soluble and a cellulose ester toughening agent swelled in a relatively low boiling solvent, said filler being soft, flexible and waterproof, will set up rapidly without substantial shrinkage and may be contoured subsequently to the initial set.

RICHARD ALMY.