Waterproof breathable high-vis arc resistant laminate

Abstract

A fabric for use in garments worn by electrical workers is constructed of at least three layers including a high visibility face fabric layer; an intermediate expanded polytetrafluoroethylene membrane layer, coated with polyurethane; and an inner layer comprised of flame resistant, high temperature fibers.

Description

This invention relates generally to garments and, more specifically to garment fabrics that meet high visibility, flame resistance, electric arc thermal performance and other industry standards.

BACKGROUND OF THE INVENTION

Garments made from flame resistant (FR) fibers provide electrical workers the needed protection from danger caused by electric arcs which may pass near them in the event of an accidental discharge in high voltage equipment and transmission lines, leading to potentially serious injuries. Such garments when made from flame retardant cotton or other non breathable fabrics are uncomfortable in warm environments because of the heavyweight fabric required for such FR protection. Most of these garments also lack the waterproofness needed to protect the workers from rain. Current waterproof garments that do provide arc protection are made of PVC coated Nomex® that do not have any breathability, leading to extreme discomfort for electrical workers.

Various industry standards define minimally acceptable performance characteristics or properties for special purpose fabrics, but not all fabric standards are mandated for every one of such fabrics. For example, fabrics used in garments for electrical workers are required to meet certain standards but not others. On the other hand, it may well be beneficial to provide garments with additional, non-mandated performance characteristics as a matter of, for example, comfort, as opposed to safety.

Some of the more relevant standards are described briefly below.

The ANSI/ISEA 107-1999 standard establishes a set of performance criteria for high-visibility apparel. The standard defines three garment categories that are based on worker hazards and tasks, complexity of the work environment or background, and vehicular traffic and speed. Class 1 garments are intended for use in activities that permit the wearer's full and undivided attention to approaching traffic, and where there is ample separation of the worker from traffic, which should be traveling no faster than 25 miles per hour. Class 2 garments are intended for use in activities where greater visibility is necessary during inclement weather conditions or in work environments with risks that exceed those for Class 1. Garments in this class also cover workers who perform tasks that divert their attention from approaching traffic, or that put them in close proximity to passing vehicles traveling at 25 miles per hour or higher. Class 3 garments provide the highest level of visibility, and are intended for workers who face serious hazards and often have high task loads that require attention away from their work.

The ASTM F1506 standard is a performance specification for textile material for wearing apparel for use by electrical workers exposed to momentary electric arc and related thermal hazards. This specification provides performance requirements for clothing worn by electric utility workers and other personnel working around energized parts. In addition to non-thermal requirements, the standard requires the fabric to be flame-resistant; that is, to not ignite and continue to burn after exposure to an ignition source.

The NFPA 70E standard addresses electrical hazard threats that are present in the workplace. NFPA 70E requires that the employer shall document the incident energy exposure of the worker when it has been determined that the worker will be performing tasks within the flash protection boundary. NFPA bases incident energy exposure levels on the working distance of the employee's face and chest areas from a prospective arc source for the specific task to be performed. Flame Resistant Clothing and Personal Protective Equipment are specified that provide an adequate level of protection based upon on the incident energy exposure associated with the specific task.

The ASTM F 1959 standard is used to measure the arc rating of materials intended for use as flame resistant clothing for workers exposed to electric arcs that would generate heat flux rates from 84 to 25 120 kW/m² [2 to 600 cal/cm²s].

The ASTM D 3393 standard sets forth the minimum requirements for hydrostatic resistance of fabrics coated with rubber or plastics. Coated fabrics satisfying these requirements are considered to be waterproof.

There is a continuing need for multi-standard-compliant fabric for use in garments, and especially garments worn by electrical workers, that not only meet certain mandated requirements, but that also provide other comfort-related benefits as well.

BRIEF SUMMARY OF DISCLOSED TECHNOLOGY

In accordance with one aspect, there is described a fabric comprised of at least three layers including a high visibility face fabric layer, an intermediate expanded polytetrafluoroethylene membrane layer; and an inner layer comprised of flame resistant, high temperature fibers.

In another aspect, there is disclosed a fabric for use in garments exposed to electrical equipment comprising: a first outer layer constructed of plain woven modacrylic material; a second intermediate layer constructed of an untreated, expanded polytetrafluorethylene membrane coated on one side with polyurethane or polyester; and a third inner layer comprised of a tricot jersey material composed of flame resistant, high temperature fibers.

The disclosed technology will now be described in greater detail in connection with the drawing identified below.

BRIEF DESCRIPTION OF THE DRAWING

The single FIGURE illustrates a cross section of a fabric in accordance with an exemplary, non-limiting implementation of the technology disclosed herein.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawing, an exemplary, non-limiting embodiment comprises a fabric 10 of three-layer laminate construction that includes an outer or face fabric 12, an intermediate fabric or layer 14 and an inner fabric or layer 20. In one non-limiting exemplary implementation, a plain woven 6.5 ounce per square yard (opsy), high visibility yellow (or orange) fabric (e.g., fabric #W825 available from Glen Raven Inc. of Glen Raven, N.C.) may be utilized as the face fabric 12.

The intermediate layer 14 in the non-limiting exemplary implementation may be a treated expanded polytetrafluroethylene or a bi-component film comprising an untreated expanded polytetrafluoroethylene membrane 16 with a conventional polyurethane (or polyester) coating 18 shown on the upper side thereof. It will be understood, however, that the coating 18 could be on either side of the membrane 16.

The inner layer 20 of the non-limiting exemplary implementation may be a tricot (1.75 ospy) jersey material available from SSM Industries, Inc. of Spring City, Tenn. that utilizes flame resistant high temperature fibers such as Nomex®.

In the described example, a commercially available flame resistant polyurethane adhesive is used to secure the laminations. Thus, as viewed in FIG. 1, adhesive layers 22, 24 are applied between the adjacent layers 12 and 14 and layers 14 and 20.

It will be appreciated that the fabric 10 as shown in the Figure is not drawn to scale and does not necessarily depict accurate relative thicknesses. Thicknesses of the fabrics, coatings and adhesives may vary depending on fabric application and other factors. In an example implementation, the thickness dimensions may be (but are not limited to) the following:

• • Outer layer: 0.029 in.
  • Intermediate layer: 0.00172 in.
  • Polyurethane coating plus adhesive layer: 0.00028 in.
  • Inner layer: 0.0090 in.

The fabric as described was tested and found to be in compliance with at least the minimum guidelines in each of the above-described standards mandated for electrical workers, but also with the non-mandated waterproofness standard. Thus, the garment fabric disclosed herein provides acceptable performance in terms of high visibility, flame resistance, electric arc and thermal properties and waterproofness (passing the Mulle waterproofing test), with good breathability (MTVR in the range of 2500-5600 g/m²/24 hrs. depending on the construction and the adhesive lay down).

It will be appreciated that other equivalent known fabric compositions may be used for any one or more of the layers of the laminate construction.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A fabric comprised of at least three layers including a high visibility face fabric layer, an intermediate expanded polytetrafluoroethylene membrane layer; and an inner layer comprised of flame resistant, high temperature fibers.

2. The fabric of claim 1 wherein said face fabric layer comprises a plain-woven modacrylic based fabric.

3. The fabric of claim 2 wherein said face fabric layer has a weight of substantially 6.5 opsy.

4. The fabric of claim 1 wherein said inner layer comprises a tricot jersey material.

5. The fabric of claim 2 wherein said inner layer comprises a tricot jersey material.

6. The fabric of claim 1 wherein said face fabric layer is high-visibility yellow or orange in color.

7. The fabric of claim 1 wherein said inner layer has a weight of substantially 1.75 opsy.

8. The fabric of claim 1 wherein said three layers are laminated together using a flame resistant polyurethane adhesive applied between adjacent layers.

9. The fabric of claim 5 wherein said three layers are laminated together using a flame resistant polyurethane adhesive applied between adjacent layers.

10. The fabric of claim 1 wherein said membrane is coated with polyurethane.

11. A fabric for use in garments exposed to electrical equipment comprising:

a first outer layer constructed of plain woven modacrylic material;

a second intermediate layer constructed of an untreated, expanded polytetrafluorethylene membrane coated on one side with polyurethane or polyester; and

a third inner layer comprised of a tricot jersey material composed of flame resistant, high temperature fibers.

12. The fabric of claim 11 wherein said face fabric layer has a weight of substantially 6.5 opsy.

13. The fabric of claim 11 wherein said inner layer has a weight of substantially 1.75 opsy.

14. The fabric of claim 11 wherein said face fabric layer is yellow in color.

15. The fabric of claim 11 wherein said three layers are laminated together using a flame resistant polyurethane adhesive applied between adjacent layers.