Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Woven fabric – Including strand which is of specific structural definition
Reexamination Certificate
2001-07-31
2004-03-02
Ruddock, Ula C. (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Woven fabric
Including strand which is of specific structural definition
C442S301000, C442S302000, C428S364000, C428S365000, C428S370000, C428S373000, C428S374000, C008S920000, C008S924000, C008S925000, C008S934000
Reexamination Certificate
active
06699805
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to flame resistant fabrics. More particularly, the present invention relates to dyed fabrics containing melamine fibers, as well as processes used to dye melamine fabrics.
BACKGROUND OF THE INVENTION
Melamine is a material used in the manufacturing of inherently flame resistant fibers. Melamine fibers are highly resistant to heat decomposition and are therefore desirable in the manufacture of flame resistant garments intended for environments in which flames or extreme heat will be encountered. For example, melamine fibers are occasionally used in the construction of outer shells for firefighter turnout gear.
Although highly flame resistant, melamine fibers have relatively low abrasion resistance due to the low tenacity of the fibers. Because of this, melamine fibers are typically blended with other, higher tenacity, fibers when used in the construction of various garments. Such blending is typically necessary to satisfy various fabric standards, such as those specified by the National Fire Protection Association (NFPA), which establishes fabric guidelines for the firefighting industry. Normally, the fibers blended with the melamine fibers are similarly inherently flame resistant. By way of example, aramid fibers (e.g., para-aramid fibers) can be blended with the melamine fibers to achieve a commercially viable garment material.
After such fabric blends have been constructed, they are usually dyed a desired shade of color. Where the melamine blend includes an aramid, typically only the melamine component of the blend is dyed due to the adverse affects the acidic conditions generally considered necessary for dyeing or coloring aramid fibers have on the melamine fibers. Where dark shades are desired, the melamine fibers may be blended with producer-colored aramid fibers. As is known in the art, producer-coloring involves the addition of pigment to the fibers during the fiber spinning process.
Most often, melamine blends are dyed in a jet dyeing procedure. In this procedure, the ends of the fabric (in rope form) are joined so that the fabric forms a continuous loop of material within a jet dyeing machine. Once so disposed, the fabric, along with the dyebath, is circulated through a continuous path within the machine with the aid of a venturi jet that is powered by a pump.
Although providing for dyeing of the melamine fibers, use of jet dyeing machines can damage melamine fabrics due to the relatively low tenacity of the melamine fibers within the fabrics. In particular, the agitation the fabric experiences while being circulated within the jet dyeing machine can adversely affect the strength of the melamine fibers and, therefore, the melamine fabric as a whole. For example, jet dyeing can significantly reduce the trapezoidal tear strength of melamine fabrics to the point at which they may not satisfy NFPA requirements. Accordingly to NFPA 1971, 2000 edition, fabrics used to construct outer shells of firefighter turnout gear must exhibit a trapezoidal tear strength of at least 100 newtons (N) (22 pound-force (lbf.)) in the warp and filling directions both before and after five launderings conducted in accordance with NFPA 1971.
Testing was performed to determine the effect jet dyeing has on the strength of melamine fabrics. In this testing, a 60/40 blend of melamine and para-aramid fibers was dyed in a jet dyeing machine under normal dyeing conditions. Later, the blend was tested in accordance with NFPA 1971 and was found to have trapezoidal tear strengths of 32 lbf. in the warp direction and 25 lbf. in the filling direction before laundering, and 32 lbf. in the warp direction and 25 lbf. in the filling direction after five launderings. Although these values each were greater than the 22 lbf. required by NFPA 1971, the filling direction strength values are only marginally acceptable. As noted above, further strength loss can be observed when the blends are dyed in acidic conditions in an attempt to dye or color the non-melamine component(s) of the blend. Although such acidic dyeing is not necessary when producer-colored fibers are used, producer-colored fibers are relatively expensive and are therefore economically undesirable.
In addition to strength problems, other difficulties can arise when jet dyeing melamine fabrics. Specifically, it can be difficult to attain high shade consistency when jet dyeing machines are used. Such problems may again be due to the relatively low tenacity of melamine fibers. In particular, the melamine fibers may cause excessive creasing of the fabric within the jet dyeing machine which can result in the formation of “crack” marks, i.e. relatively dark lines that form along fabric creases during the dyeing process.
In view of the above, it can be appreciated that it would be desirable to have dyed melamine fabrics that do not suffer from the aforementioned drawbacks as well as methods for dyeing the fabrics so as to avoid those drawbacks.
SUMMARY OF THE INVENTION
The present disclosure generally relates to dyed melamine fabrics and methods for dyeing melamine fabrics.
In one arrangement, the fabrics comprise a plurality of melamine fibers, wherein the flame resistant fabric has been dyed through a beam dyeing process in which the fabric has not been mechanically agitated.
In one arrangement, the methods comprise the steps of wrapping melamine fabric around a perforated beam of a beam dyeing machine such that several layers of fabric surround the beam, injecting dyebath into the beam so that it penetrates the fabric layers, and circulating the dyebath through the fabric layers until the fabric is dyed to a desired shade.
The features and advantages of the invention will become apparent upon reading the following specification.
DETAILED DESCRIPTION OF THE INVENTION
Introduction
As summarized above, various problems exist in the production of melamine fabrics. Specifically, it can be difficult to produce dyed melamine fabrics that possess good strength and shade consistency. Accordingly, this disclosure is directed to dyed melamine fabrics that are strong and/or that have good shade consistency. As used herein, the term “melamine fabric” designates any fabric that contains melamine fibers. Furthermore, it is to be noted that, when a material name is followed by the term “fiber,” the fiber described is not limited to fibers composed exclusively of the named material. Therefore, the term “melamine fiber” includes any fiber that contains melamine.
This disclosure is also directed to methods for dyeing melamine fabrics in a manner in which high strength is maintained and/or good shade consistency is achieved. The discussion that follows begins with an identification of example fabric constructions. Next, the discussion describes dyeing methods used to dye these fabrics. Finally, the discussion provides various examples of dyeing procedures and coloration results.
Fabric Construction
As noted above, the fabrics described herein comprise melamine fibers. Melamine is a material that can be used as a building block for condensation synthesis with formaldehyde to facilitate the formation of three-dimensional polymeric lattices. In the condensation reaction, methylol compounds are initially formed that react with each other to form a three-dimensional structure of methylene ether and methylene bridges. Fibers can then be formed of a condensation polymer by reacting a mixture comprising 30% to 99% molar melamine, 1% to 70% molar substituted melamine, and 0.1% to 10% molar phenols or substituted phenols, with formaldehyde or formaldehyde-liberating compounds, the molar ratio of melamine to formaldehyde ranging from 1:1.5 to 1:4.5. Suitable melamine fibers are currently available from BASF under the tradename Basofil™ and can be formed as described in U.S. Pat. No. 5,560,990, which is hereby incorporated by reference into this disclosure Typically, the melamine fibers are blended with at least one other type of fiber (i.e., blending fibers) to form a fabric blend. To attain a highly flame resistant end fa
Ruddock Ula C.
Southern Mills, Inc.
Thomas Kayden Horstemeyer & Risley LLP
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