DOUBLE DENSITY SLIPPER
Field of the Invention
The present invention relates to an improved slipper or footwear and more particularly to the sole of the slipper or footwear which has improved softness properties while maintaining a desirable wear resistance. The upper or the footbed part is made of lighter weight or of lower density with increased softness, better cushioning, comfort and minimum fatigue. The bottom is of relatively higher density and is reinforced to achieve greater toughness, durability ensuring enhanced foot protection and safety.
Background of the Invention
The foot contains more bones than any other single part of the body. Though it has evolved over hundreds of thousands of years in relation to vastly varied terrain and climate conditions, the foot is still vulnerable to environmental hazards such as sharp rocks and hot ground, which shoes can protect against.
The footwear industry is an old and bundled art. The industry is constantly attempting to design new products with aesthetic appeal, as well as being comfortable and having ease of construction and long lasting.
Most styles of slipper offer little or no support for the tender arch of the human foot. This is essential to children, whose young feet are still developing. The lack of support can allow the foot to roll inwards during walking, which can cause many health issues. Of course, opposing studies suggest that the introduction of rigid heels in slippers and shoes of infants and toddlers can actually inhibit a child's ability to learn to walk as quickly as they would otherwise.
In a conventional slipper the insole and outsole compound are made with same material composition and expansion properties with only the colour difference. Further in the conventional slipper both the compounds expand in same percentage and shrink in same percentage. The side profile of the conventional slipper is either straight or round.
The conventional slippers are either soft with cushion feeling in the insole but lacking foot protection and durability, or, hard with more foot protection and durability but without any cushion feeling in the insole.
Further in the present slipper the material composition, expansion properties and colour all are different in both insole and outsole compound as compared to the conventional slipper. The expansion and shrinkage percentage is controlled in spite of different insole and outsole compound are used in the present invention as compared to the conventional slipper.
The present invention discloses a new improved slipper made by combining a soft insole with a hard outsole made by specially designed formulation and selected polymeric combination and other chemicals. The object of the present invention is to make a slipper which has a comfortable and soft insole with a hard and anti skid outsole to protect the foot and increase the durability of the footwear.
While wearing slippers can offer comfort, it can also be a danger, in both terms of walking and movement, as well as the development of the young foot.
Summary of Invention
Accordingly it is an object of the present invention to provide an improved slipper. The slipper includes an outsole, an insole and straps. The present invention describes an improved slipper wherein the insole compound and
outsole compound are formulated separately and later they are enjoined together to make a single sheet
It is an object of the present invention to provide a slipper wherein the insole is soft with cushion feeling for better comfort and also hard outsole for better foot protection and durability. The comfort felt by the wearer of a shoe or slipper depends, in large part, on the ability of this foam insole to redistribute the various forces imposed on the foot during walking and standing. These forces are greatest in the heel, arch and forefoot regions.
Another object of the present invention is to make a slipper which is light in weight, has a comfortable and soft insole with a hard and anti skid outsole to protect the foot and increase the durability of the footwear.
Still another object of the present invention is to ensure a mass production system without any extra workmanship and thereby to reduce the manufacturing cost thereof.
Another object of the present invention is to provide the slippers with colouring, printing and sizing choices so as to meet the necessities of individuals and institutions.
Yet another object of the present invention is to provide a slipper, which can be recycled and is environment friendly i.e ecofriendly and reproducible so as to bring forth an economical material and manufacture.
Description of the Accompanying Drawings:
Fig 1: Schematic flow chart of Sheet production process.
Fig 2: Schematic flow chart of Strap production process.
Fig 3: Schematic flow chart of Assemble workshop process.
Fig 4: Schematic diagram illustrating an exploded and side isometric view of the footwear in accordance with the present invention.
Detailed Description of the Invention
Slippers are presently under use at places such as hotels, hospitals, saunas, common baths, pools etc. as they are practical and handy. At common baths, saunas and pools, slippers are necessarily used in place of bare foot. Even in some special pools, the folk participate particularly with their own slippers.
The present invention is explained in greater detail below. This description is not intended to be a detailed catalog of all the different ways in which the invention may be implemented, or all the features that may be added to the instant invention. For example, features illustrated with respect to one embodiment may be incorporated into other embodiments, and features illustrated with respect to a particular embodiment may be deleted from that embodiment. In addition, numerous variations and additions to the various embodiments suggested herein will be apparent to those skilled in the art in light of the instant disclosure, which do not depart from the instant invention. Hence, the following specification is intended to illustrate some particular embodiments of the invention, and not to exhaustively specify all permutations, combinations and variations thereof.
The present invention describes an improved slipper wherein the insole compound and outsole compound are formulated separately and later they are enjoined together to make a single sheet. Desired sizes are then cut from the said sheet and enjoined together with the straps to hold the foot. The most suitable material used for insole is Ethyl Vinyl Acetate co-polymer blended with suitable choice of compatible polymers, chemicals and fillers.
The insole and out sole is made using the Ethyl Vinyl Acetate (also known as EVA). EVA is the copolymer of ethylene and vinyl acetate. The weight percentage of vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene.
It is a polymer that approaches elastomeric materials in softness and flexibility, yet can be processed like other thermoplastics. The material has good clarity and gloss, better properties, low-temperature flexibility, stress-crack resistance, hot-melt adhesive, water proof properties, and resistance to UV radiation.
EVA has little or no odour and is competitive with rubber and vinyl products in many electrical applications. EVA is one of the materials popularly known as expanded rubber or foam rubber. EVA foam is used as padding in equipment for various sports such as ski boots, hockey, boxing, mixed martial arts, wakeboard boots, water ski boots, fishing rods and fishing reel handles. It is typically used as a shock absorber in sports shoes, for example. EVA slippers and sandals are nowadays very popular because of its properties like light weight, easy to mould, odourless, glossy finish, and cheaper compared to natural rubber. In fishing rods, it is used to construct handles on the rod-butt end. EVA can be used as a substitute for cork in many applications.
The manufacturing process of the slipper is broadly divided into three major operational processes.
1. Sheet production.
2. Strap production.
3. Assemble workshop
1. Sheet Production Process:- Fig. 1 depicts to the Sheet production process,
which is described in accordance with principles of the present invention.
Referring to Fig. 1, the different steps of the sheet production process are
described below:
Step 1: Weighing of different chemicals/ polymers/ fillers is done as per
formula. The weighing is done using the bale cutter or weighing scale in
the Compounding room.
Step 2: The compounded ingredients are mixed in intermix/kneader at a
temperature being 100-110 degree Celsius.
Step 3: Mixed compound is then added with certain chemicals on two roll
mill.
Step 4: After chemical mixing, the compound is again fed into two roll
mill for further uniform mixing of all ingredients.
Step 5: Uniformly mixed compound is fed into calendar for sheeting out
and cutting into pieces as per required size/ weight.
Step 6: Pieces that are cut are laminated and then they are weighed to
form blanks according to the requirement.
Step 7: The ready blanks are then loaded into respective moulds in
hydraulic press at 160 degrees centigrade and with 1.5 ton/sq. inch
pressure for 15-20 minutes for curing.
Step 8: Later on, the cured blanks or sheets are put into water tank for
cooling
Step 9: At last cooled sheets are made free of mould flashes and are
stacked in sheet stock.
2. Strap Production Process:- Fig. 2 depicts to the Strap production process,
which is described in accordance with principles of the present invention.
Referring to Fig. 2, the different steps of the strap production process are described below:
Step 1: Weighing of different chemicals/polymers/fillers is done as per
formula. The weighing is done using the bale cutter or weighing scale in
the Compounding room.
Step 2: The compounded ingredients are mixed in intermix/kneader at a
temperature between 80 - 90 degree Celsius.
Step 3: The mixed compound is then fed into two roll mill for making
slabs which are cooled and stored.
Step 4: cooled slabs are again rewarmed with certain chemicals in two
roll mill.
Step 5: The chemical mixed compound is then fed into for sheeting out
and cutting into pieces as per required size/weight to form blanks.
Step 6: The blanks are sized and weighed as required and then dusted
with dusting powder and then stacked.
Step 7: The ready blanks are then put to curing in hydraulic press by
loading them in respective moulds.
Step 8: The cured straps are then removed from press, made free of mould
flashes manually and then cooled and stored.
Step 9: At last the stored straps are sent for trimming after which finished
straps are taken into strap stock for further process.
3. Assemble Section Process:- Fig. 3 depicts to the Assemble Section Process, which is described in accordance with principles of the present invention. Referring to Fig. 3, the different steps of the Assemble Section Process are described below:
Step 1: Sheets are received from Sheet Stock and cut into soles by cutting
machines /cutting knives.
Step 2: The cut soles are then drilled at three places being one at the top
half and two on either sides of the slipper just below the middle half of the
slipper to fit in the straps by strap putting machine.
Step 3: The cut and drilled soles are then screen printed by screen and ink.
Printing is then done on the insole of the said slipper to make it attractive
and appealable. The said slipper then goes through the process of buffing
for giving side finishing and giving multi dimensional shape. It also gives
a smoother and a brighter finish
Step 4: Profiling of the printed sole is made by the profile grinder.
Step 5: The grinded soles are then fitted with straps, received from strap
stock, by strap putting machine.
Step 6: The strap fitted soles or slippers are put into water tank for
cleaning.
Step 7: The cleaned slippers are then dried by blowers.
Step 8: The dried slippers are applied with some finishing materials for
better look and sales appeal.
Step 9: The finished slippers are put to quality checking and pairing.
Step 10: The quality checked slipper pairs are attached with tag cards and
packed into boxes.
Step 11: The packed boxes are put into cartoons as per required size
assortment.
Step 12: The packed cartoons are sent to finished goods, stock and are
ready for
The above described manufacturing process provides slipper in which the insole is soft with cushion feeling for better comfort and hard outsole for better
foot protection and durability. Thus after all the three steps we get fresh slipper according to our invention.
To make the insole soft, EVA along with other compatible polymers is mixed with different chemicals namely Zinc Oxide, Zinc Stearate, Stearic Acid, Dicumyl Peroxide, Calcium carbonate, etc. as per the following formulation: -
Polymer = 60% to 65% Chemicals = 10% to 15% Fillers = 20% to 30%
The insole compounds are mixed in Intermix / kneader machine at a temperature 100 to 110 degree Celsius for 15 to 20 minutes which is in the form of a lump is put into two roll mill for mixing with some chemicals. The chemical mixed batch is transferred to another two roll mill for further mixing of the compound uniformly. The uniformly mixed batch is finally fed into calendar for sheeting out in the form of thin sheets which are cut into required sizes and weights.
Similar is the process for sole compounds with EVA and other ingredients according to different formulations.
Fig 4 is a schematic diagram illustrating an exploded and side isometric view of the slipper which we get after the above mentioned manufacturing process. The optimum thickness of top layer of the slipper is 1.5 mm; optimum thickness of middle layer of the slipper is 8 mm and optimum thickness of bottom layer of the slipper is 7mm. Thus the optimum thickness of the slipper is 16.5 mm and optimum buffing of the slipper is 5mm. The colour and printing of the slipper can be changed according to the requirement.
The foregoing is illustrative of the present invention, and is not to be construed as limiting thereof. While embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. In the claims that will follow subsequently in the complete specification, the indefinite article "A", or "An" refers to a quantity of one or more of the item following the article, except where expressly stated otherwise. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the claims that will follow in the complete specification will define the scope of the invention and the methods and structures within the scope of these claims and their equivalents will be covered thereby.

We claim:
1. An improved slipper comprising of:
an insole compound formulated separately with most suitable material
Ethyl Vinyl Acetate co-polymer blended with suitable choice of compatible
polymers, chemicals and fillers; and
an outsole compound formulated separately with most suitable material
used for outsole is Ethyl Vinyl Acetate co-polymer blended with suitable
choice of compatible polymers,chemicals and fillers;
which are both later enjoined by together to make a single sheet.
2. The improved slipper as claimed in claim 1, wherein weight percentage of vinyl acetate in Ethyl Vinyl Acetate co-polymer usually varies from 10 to 40%, with the remainder being ethylene.
3. The improved slipper as claimed in claim 1, wherein to make the sole and insole compounds, EVA along with other compatible polymers is mixed with different chemicals namely Zinc Oxide, Zinc Stearate, Stearic Acid, Dicumyl Peroxide, Calcium carbonate etc. as per the following formulation:-Polymer = 60% to 65%; Chemicals = 10% to 15%; and Fillers = 20% to 30%.
4. The improved slipper as claimed in claim 3, wherein the mixture is mixed for about 15 to 20 minutes in Intermix/Kneader at temperature 100 - 110 degree , till the said mixture gets completely mixed; then the compound then to two roll mill for further mixing with certain chemicals; and the chemical mixed compound is taken to another two roll mill for uniform dispersion of compounding ingredients and lastly the compound is passed through calendar for sheeting out and cutting into thin pieces or blanks of required size and weight
5. The improved slipper as claimed in claim 1, wherein the insole as well as the outsole are made with the blend of chemicals and fillers as per formulation and by mixing in Intermix / Kneader under Temperature of 100-110 degree Celsius.
6. The improved slipper as claimed in claim 1, wherein the blanks (Sheet Shape) of both insole and outsole are then laminated separately in the proportion of thickness, size and weight.
7. The improved slipper as claimed in claim 1, wherein the blanks (Sheet Shape) of both insole and outsole are then compressed through Hydraulic press at 160 degrees centigrade and with 1.5 ton/sq. inch pressure for 15 to 20 minutes.
8. The improved slipper as claimed in claim 7, wherein the compressed sheets are then allowed to cool in water and are stacked followed by storing in sheet stock; thereafter, sheets are taken from sheet stock and cut into slipper-soles of desired sizes.
9. The improved slipper as claimed in claim 1, wherein slipper-soles of desired sizes are cut from the said sheet and enjoined together with the straps or any other means to hold the foot.
10. The improved slipper as claimed in claim 1, wherein the insole is soft with cushion feeling for better comfort and also hard outsole for better foot protection and durability.