U.S. patent number 3,724,107 [Application Number 05/196,663] was granted by the patent office on 1973-04-03 for elastic overshoes.
This patent grant is currently assigned to The B. F. Goodrich Company. Invention is credited to Winnifred B. Makinen, Raymond C. Srail.
United States Patent |
3,724,107 |
Makinen , et al. |
April 3, 1973 |
ELASTIC OVERSHOES
Abstract
Elastic overshoes of the type which are stretched over the
street shoes, commonly called "rubbers," are molded from a material
which is elastomeric and vulcanized, and which when heated,
stretched, and cooled, will retain the stretched size and shape.
The overshoes may be heated and pressed into a solid cake for
storage and shipping. Before use, the overshoes are reheated,
stretched over the street shoes of the user while hot, and when
cooled, will retain the proper size and shape to fit the user's
shoes.
Inventors: |
Makinen; Winnifred B. (Berea,
OH), Srail; Raymond C. (Parma, OH) |
Assignee: |
The B. F. Goodrich Company (New
York, NY)
|
Family
ID: |
22726321 |
Appl.
No.: |
05/196,663 |
Filed: |
November 8, 1971 |
Current U.S.
Class: |
36/7.3 |
Current CPC
Class: |
A43B
3/16 (20130101) |
Current International
Class: |
A43B
3/16 (20060101); A43b 001/10 () |
Field of
Search: |
;36/2.5R,4,7.1,7.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawson; Patrick D.
Claims
We claim:
1. Reshapable overshoes made of a material having minute coherent
domains of vulcanized elastomer, and of a substance which is
extensible only when hot, vulcanized in a size and shape smaller
than those of the shoes on which they are used.
2. Overshoes as in claim 1, in which the domains are of vulcanized
natural rubber and of trans 1,4 polybutadiene.
3. Overshoes as in claim 1, of a size larger than that in which
they were vulcanized, having internal strains holding them in the
larger size.
4. Overshoes as in claim 1, compressed into a compact mass for
convenience in shipping.
5. A process for shaping overshoes to fit a pair of shoes, which
comprises vulcanizing a material having minute coherent domains of
elastomer and of a substance which is extensible only when hot, to
produce overshoes of a size too small to fit the shoes, heating the
overshoes, stretching while hot to a size which fits the shoes, and
cooling while stretched.
6. A process as in claim 5, including the intermediate steps of
heating the vulcanized overshoes, compressing while hot to a
compact shape for shipment, and cooling while compressed.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
The materials used in the practice of this invention are the
subject of applications for patent of James Sidles and Raymond C.
Srail, Ser. No. 189,026 filed Oct. 13, 1971 and of Gary A. Harpell,
Ser. No. 191,118 filed Oct. 20, 1971 both assigned to the assignee
of this application.
BACKGROUND OF THE INVENTION
Elastic overshoes which are put on by stretching over the user's
street shoes, and which therefore require no fasteners, have been
made in two principal constructions. In one construction, these
"rubbers" are built on lasts, of an exact size and shape to fit a
particular style and size of shoe, and generally with some fabric
reinforcement, especially in the sole portion. If fabric is used in
the uppers, it has of necessity been a stretchable fabric, such as
stockinet. The other construction is a simple molded all-rubber
article containing no fabric, often made in small, medium, and
large sizes only, so that considerable stretching may be needed to
pull it over a shoe not quite large enough to require the next
larger size.
The fabric reinforced rubbers will not stretch enough to conform to
sizes and shapes other than those of the particular shoes they are
made to fit, so they are often purchased too loose, and then shift
in position during walking, or even drop off. The all-rubber
articles are subject to tearing, and if highly stretched may be
uncomfortable to wear.
SUMMARY OF THE INVENTION
We have found that rubber overshoes can be made of a particular
kind of elastomeric material which can be reshaped while hot, and
which will retain the new size and shape as long as the material is
not reheated.
This permits overshoes to be molded in a single size and shape to
permit use on a wide range of sizes and styles of shoes. For
example, men's rubbers may be molded in a single size and shape,
slightly smaller than the smallest normal men's size, and in a
neutral shape which is neither a right nor left shape. The user
will then heat a pair of these rubbers, quickly pull them over his
street shoes, and when cool, they will be the exact size and shape
to fit snugly without excessive tension.
THE DRAWINGS
In the accompanying drawings, FIG. 1 shows an overshoe made
according to this invention in a small size and neutral shape.
FIG. 2 shoes the same overshoe compressed for storage and
shipment.
FIG. 3 shows the same overshoe resized and shaped to fit a
particular size and style of men's shoe for the right foot.
DETAILED DESCRIPTION
The material from which the overshoes of this invention are made is
one consisting of minute domains of two different polymeric
substances, one of which is a vulcanized elastomer, and the other
of which is essentially inextensible at room temperature but is
either elastomeric or plastic at a higher temperature, and is
bonded to the vulcanized elastomer. There are two principal ways in
which such a material can be prepared.
One way is to add vulcanizing agents and such pigments and other
additives as may be desired to natural rubber, or to any of the
vulcanizable synthetic rubbers which are highly elastic at ordinary
outdoor temperatures, and also to mix in a substantial quantity of
a material which is thermoelastic or thermoplastic, and which will
bond to the rubber during vulcanization. For example, trans 1,4
polybutadiene can be described as thermoelastic, since it is a
diene polymer which is crystalline and essentially inextensible at
room temperature, but is highly extensible at about 200.degree. F,
so that it will form a firm bond to the rubber during vulcanization
and can be shaped while hot. This mixture is then vulcanized in the
desired shape.
The other way to prepare such a material is to make a block
copolymer with a central block of thermoplastic and terminal blocks
of vulcanizable elastomer. The central block may be polystyrene of
molecular weight about 40,000 to as high as 400,000, and the
terminal blocks may be elastomeric polybutadiene or polyisoprene of
molecular weight about 8,000 to 100,000 or more. Other combinations
of synthetic polymers having similar physical properties can be
prepared. Vulcanizing agents are added, with or without added
vulcanizable elastomer, depending on the proportions of the
ingredients in the block copolymer and on the properties which are
desired in the finished product, and the material is vulcanized in
the desired shape. In all cases the total quantity of elastomer
should be at least half of the volume of the material.
In a preferred embodiment of this invention, 100 parts by weight of
natural rubber are mixed with 40 parts carbon black, eight parts
zinc oxide, one part stearic acid, 0.5 parts sulfur, two parts
dithiodimorpholine, 1.25 parts benzothiazyl disulfide, and if
desired, small quantities of softener and antioxidant. To this
composition is then added one-third of its weight of trans 1,4
polybutadiene, and the mixture is thoroughly blended.
The foregoing mixture is molded and vulcanized in a mold having a
cavity the approximate size and shape of the smallest normal men's
size of rubbers, except that it is symmetrical rather than right or
left shoe shape. The molded rubber shown in FIG. 1 has a sole
portion 10 and an upper portion 11, which may have a small bead 12
for reinforcement of the edge. The outside of the sole 10 is
preferably somewhat arched under the instep 13, and in addition is
made somewhat thinner than the remainder of the sole, so that
longitudinal stretching will occur to a greater extent at the
instep than elsewhere. The sole under the toe and ball of the foot
14, and also under the heel 15, is formed with a pattern of
protuberances or ribs as is usual, to minimize slipping.
Preferably, the tread pattern of the sole and heel is extended
slightly around the edges so that the pattern will still extend
completely across the sole and heel surfaces even after substantial
stretching.
One of the molded and vulcanized overshoes is heated to 200.degree.
F, dropped into a cold cylindrical plunger mold and quickly
compressed under high pressure. Because of the thermoelasticity of
the material, the product takes and retains the exact shape, as
long as it is kept cool. After cooling in the mold, the overshoe is
a dense cylindrical disc 16, as shown in FIG. 2. A pair of these
compressed overshoes is then packaged for shipment and sale in a
small, conveniently shaped container.
The user removes the discs 16 from the package and reheats them to
a temperature of about 200.degree. F, which may be done in boiling
water, but preferably in an oven so as to avoid spillage of hot
water. As the overshoes heat up, they spontaneously revert to the
vulcanized shape shown in FIG. 1, unfolding progressively as the
heat penetrates. The user then grasps one of the hot overshoes and
quickly slips it over his street shoe, then places the other
overshoe over his other street shoe, and allows them to cool to
room temperature, which will occur very quickly. Thus, the reshaped
overshoe, as shown in FIG. 3, will conform to the size and shape of
the shoe, including unsymmetrical distension of the toe portion 17
to fit over the great toe location of the street shoe.
The overshoes can be left on the street shoes as long as may be
desired, and will fit snugly without excessive pressure. They may
be pulled off whenever they are not needed, as they retain
sufficient elasticity for that purpose. They will then be the
exactly proper size and shape to be put on the shoes on which they
were shaped, or on others of the same size and shape. If the user
should wear other shoes of a different style, requiring a different
shape, the overshoes are reheated in the oven and reshaped to fit
the other shoes.
Although a single style of rubbers is shown, others, designed to
fit men's, women's, or children's shoes of various kinds with
varying heights of heels, or with or without heel covering, or with
varying heights of uppers, can be made in accordance with this
invention.
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