Patent Application
20250113893
The present invention relates to shoe covers having slip-resistant properties. The shoe covers are generally made of a variety of fabric substrates, such as woven reusable fabrics and nonwoven disposable fabrics, e.g. polypropylene fabric. In general, most readily available fabrics lack slip-resistant properties. There are some fabrics that have slip-resistant properties, but they are more rigid and more expensive, thus not the best solution for softness, comfort, and low cost. Disposable shoe covers must be relatively inexpensive due to their application. The need for one-time use shoe covers is greater in hospitals and operating rooms, where preventing contamination or keeping sterilized environment is important. However, shoe covers are used indoors on different surfaces in many different residential and commercial settings. Those surfaces can be smooth and slippery, posing a serious safety hazard. Since shoe covers are put over the shoes of the wearer, the only grip left once they are put on is the grip coming from the shoe cover material.
When making reusable shoe covers, manufacturers have used different rubberized materials for the sole portion of the shoe cover and another less expensive material for the uppers of the shoe cover. This design is normally costly and requires cutting separate blanks in different shapes and sewing the blanks together, which makes it not suitable for manufacturing disposable shoe covers. One of the biggest challenges that a manufacturer of disposable shoe covers faces ismaking disposable shoe covers that have slip-resistant properties at a low cost. In the past, manufacturers have tried different methods to make slip-resistant disposable shoe covers, but none of the known methods provides an optimal solution that balances cost, performance, and production speed, while using readily available materials.
One method to make slip-resistant disposable shoe covers is to make a blank from nonwoven fabric that has slip-resistant properties and form the entire shoe cover from the same fabric material. Although this method works to some degree, the fabric cost is quite high. Since the slip-resistant properties are only necessary at the bottom portion of the shoe cover, which contacts the ground, the rest of the fabric slip-resistant properties are never used but are paid for by the manufacturer and the end user. In addition, adding slip-resistant properties to a fabric normally makes the fabric more rigid, which can make the shoe cover uncomfortable and noisy.
Another method used to make slip-resistant shoe covers is by sewing an exposed rubber rib to the bottom portion of the shoe cover. This method provides some slip resistance, but its effect is limited by the width of the rubber rib. The wider the rib, the better the slip-resistance of the shoe covers. However, increasing the width of the rubber rib can make the shoe cover uncomfortable and costly. Since the rubber rib is exposed and designed to contact the ground, the shoe cover user will be stepping over the rubber, which can be very uncomfortable. In addition, the cost of the rubber rib can be as much as or more than the whole shoe cover blank. Also, this method is time consuming and involves extra sewing steps.
A third method of making slip-resistant disposable shoe covers is by printing, painting, or spraying various patterns on the bottom section of the shoe covers. These methods are time consuming, costly, require a high-volume production, and the slip-resistance effect is limited. In many instances the print on the bottom of the shoe cover does not provide any grip and it is just a visual appearance. There are some PVC (rubber) based inks that can provide a good grip, but the cost for such prints is very high and much more than the entire shoe cover.
Another known method of making slip-resistant shoe covers is by applying different polymers that have slip resistant properties in various patterns directly on to a nonwoven fabric being used to make the shoe cover body. Those polymers are designed to adhere to the substrate materials and may require additional consumables, such as adhesives and glues. The polymers used are often proprietary to the companies that make them and require large purchasing volumes and significant investment for the application process in order to be automated. Also, the slip-resistant effect and the durability are somewhat limited.
There is a need for slip-resistant shoe cover that is low in cost, comfortable, quick to manufacture and makes use of readily available materials.
The shoe cover in exemplary embodiments of this invention solves the problem of manufacturing slip-resistant shoe covers by ultrasonically welding a slip-resistant fabric strip, pre-cut to a desired width from a fabric with slip-resistant properties, to another less expensive fabric that does not have slip-resistant properties. The shoe cover according to exemplary embodiments comprises of a body shaped to surround the foot of the wearer. The body is made of a fabric comprising an inside surface and an outside surface, the outside surface designed to contact the ground when the shoe cover is being worn, and a slip-resistant fabric strip, pre-cut to a desired width from a different fabric that has non-slip properties, ultrasonically welded to the bottom outside surface of the shoe cover.
Another aspect of the present invention relates to a method of making slip-resistant shoe cover comprising ultrasonically welding of a fabric strip with slip-resistant properties to another fabric without slip-resistant properties, the latter used to form the body of the shoe cover. The body of the shoe cover comprises an inside surface and an outside surface. The inside surface of the shoe cover is designed to contact the wearer's shoe and the outside surface is designed to contact the floor or ground. The slip-resistant fabric strip is ultrasonically welded to the bottom outside surface of the shoe cover.
Ultrasonic welding is the joining of two or more substrates through the use of heat generated from high-frequency mechanical motion. It is accomplished by converting high-frequency electrical energy into high-frequency mechanical motion. Pressure is applied to two or more overlapping fabrics to create friction. Friction produces heat and melts the two fabrics at one or more contact points. Once cooled down, a solid homogeneous weld between the two fabrics is created. The ultrasonic welding process is easy and quick to setup, consumes low energy, and has high productivity speed.
These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, where:
Referring to
In accordance with exemplary embodiments, the shoe cover 10 further includes a slip-resistant fabric strip 101 located on the bottom portion 40 and overlapping with the bottom fold 24 along the entire length of the shoe cover. The slip-resistant fabric strip is ultrasonically welded over the bottom fold 24. The slip resistant fabric strip 101 can be formed from any available nonwoven or woven fabric coated, bonded or laminated with various polymers such as Acrylics, Polyurethane, Nylon, Polyethylene, Polyvinyl Chloride, or any other polymer that provides slip resistance to the finished material. In general, fabrics are made from synthetic fibers (manufactured), natural fibers (occur in nature) or combination of both. In preferred embodiments, the fabric being used to form the slip-resistant strip 101 has a composition of 60% or more synthetic fibers in order to be weldable. The slip-resistant fabric strip 101 works best when it has a width from 2 centimeters to 6 centimeters and it is positioned along the bottom fold 24. The slip-resistant fabric strip 101 can be any desired width and can be positioned anywhere along the bottom portion of the shoe cover 40 that is designed to contact the ground. It should also be noted that a plurality of slip-resistant fabric strips can be ultrasonically welded along the bottom portion 40 of the shoe cover 10.
There are many advantages in the shoe cover of this invention having an ultrasonically welded slip-resistant strip 101 along the bottom portion 40 of the shoe cover 10.
For example, nonwoven fabrics with slip-resistant properties are 3 to 4 times more expensive than nonwoven fabrics without any slip-resistant properties. By ultrasonically welding just a small slip-resistant strip along the bottom portion of the shoe cover, the incremental cost increase of adding slip-resistance to the shoe cover is very minimal as compared to other solutions described in the background section. This invention gives the manufacturers options to experiment with various readily available fabrics and find the one that best suit their needs when trying to achieve a balance between cost and safety. Slip-resistance is measured on a scale based on Coefficient of Friction (COF). The Coefficient of Friction is the ratio of the frictional force resisting the motion of two surfaces in contact to the normal force pressing the two surfaces together. By increasing the width or the count of the slip-resistant fabric strip 101 manufacturers can easily increase or decrease the COF of the shoe cover of the present invention while having control over the cost.
Furthermore, when the slip-resistant fabric strip 101 and the fabric blank 102 are overlapped and placed in an ultrasonic welding tool 110 a uniform joint is formed. This ultrasonically welded joint keeps the shoe cover bottom portion 40 of the present invention flat and much more comfortable when compared to other solutions.
Third, since the slip-resistant fabric strip 101 is ultrasonically welded the need for additional consumables, adhesives, glue, inks, or polymers is eliminated. Also, the ultrasonic welding process is easy and quick to setup and consumes low energy.
Fourth, the ultrasonic welding process also eliminates the need of stitching, which creates holes in the shoe cover and allows water or other liquids to penetrate the material quicker.
Another advantage of the present invention is the ability to automate the production process of slip-resistant shoe covers. The blanks 101 and 102 can be cut individually as shown on
