Do synthetic-natural fiber blends dry and wick better?

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From the text of patent documents:

Polyester/cotton blends were consistently more comfortable than 100% cotton and “Akwatek”–treated polyester over the whole range of thermal sensations.

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The wicking away of moisture is purported to help guard against irritation, as well as wetness. The wicking away of moisture, however, does not necessarily equate to reduced drying times or improved water release rates.

For example, a garment that wicks quickly may, nonetheless, have a relatively slow drying time and low water release rate. The wicking rate of a fabric is dependent upon capillary forces and is usually considered when a fluid moves along a surface, not away from the surface. The drying time or water release rate depends on the differential forces that attract and repel fluid to or from the surface. – From Optimer Inc.’s patent application below.
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I recently did some researc on Optimer, Inc.’s Dri-release (800-994-3083). Dri-release is a family of woven fabrics of very different synthetic-natural fiber blends used in sportswear.

Sierra Designs, Mammut, Berghaus, Outdoor Research and many other brands http://www.dri-release.com/partners use Dri-release.

Dri-release states that their fabric dries quicker than Coolmax Extreme and other fabrics
http://www.dri-release.com/hiw_un_dry_time.html But conspicuous by its absence is a comparison with some other fabrics, such as Schoeller’s Dryskin Extreme or Polartec’s Power Dry.

Optimer’s patent claims that a synthetic-natural fiber blend fabric is more comfortable than either cotton alone or a synthetic fabric alone.

The patent for Dri-release is for a woven fabric made from yarning containing 85-90% quick drying fiber and 10-15% hydrophilic fiber by weight. The materials used in Dri-release vary, but include such combinations as 85% polyester and 15%cotton 15%, or 88% polyester and 12% wool or 85% nylon 85% and 14% cotton. Other blends use can use linen, Tencel® and bamboo http://www.drirelease.com/news/news.php?i=0.

Recently, a “new” natural fiber, SeaCell, by SeaCell GmbH, in Rudolstadt, Germany a division of Zimmer AG, http://www.seacell.com/en/home has been introduced to the Dri-release line.

SeaCell is a lyocell-like cellulosic fiber into which both seaweed extract and silver ions are permanently incorporated. Highly breathable and soft, SeaCell will use the natural attributes of seaweed and silver. http://www.drirelease.com/news/news.php?i=2

Here’s some information from Optimer’s patent and patent application. Unfortunately, I could not find any user reviews which compared Dri-release to other fabrics. The information in the patent documents printed below raises an interesting, to wit, whether blends offer superior performance and comfort, to all natural and all synthetic fabrics.

Excerpts from the official text of patent number 5,888,914 (March 30, 1999) granted by the U.S. Patent and Trademark Office:

Synthetic fiber fabrics with enhanced hydrophilicity and comfort
Inventor: Katz; Manfred
Assignee: Optimer, Inc. (Wilmington, DE)

DETAILED DESCRIPTION OF THE INVENTION

The yarns of this invention comprise a combination of hydrophilic and hydrophobic fibers. As is well known in the art, hydrophilic fibers are fibers that exhibit a relatively high water absorption. For the purpose of this invention, hydrophilic fibers are those which will absorb at least about 15 percent of their weight in water. Examples of hydrophilic fibers include cellulosic fibers such as cotton and rayon, as well as worsted, wool and polyvinylalcohol.

Conversely, hydrophobic fibers are fibers that are relatively non-water absorptive and moisture insensitive. For the purpose of this invention, hydrophobic fibers are those fibers that will absorb from zero to 10 percent of their weight in water.

Examples of hydrophobic fibers include nylon, polypropylene, polyesters such as polyethyleneterephthalate and nylon, and polyacrylonitrile.

For the purpose of this invention, the amount of water that fibers will absorb may be measured by weighing the dried fibers, exposing the fibers to conditions of 100% relative humidity and room temperature, for a period of twelve hours, and weighing the fibers to determine the weight % of water absorbed.

The yarns of this invention may include more than one type of hydrophilic fiber and/or more than one type of hydrophobic fiber. Preferred embodiments of this invention are yarns consisting essentially of blends of polyester and cotton.

As illustrated in the examples below, it has surprisingly been found that fabrics made from fibers of blends of about 10 and about 15 weight percent hydrophilic fiber and about 85 to about 90 weight percent hydrophobic fiber are preferred by users in wear tests.

This finding is surprising because these fabrics are preferred, by a significant amount, over fabrics made from blends containing only 5% more, or 5% less, of the hydrophilic fiber.

The hydrophilic and hydrophobic fibers may be combined by any number of means known in the art. For example, the fibers may be blended as staple and then spun into yarn from which a fabric is knitted or woven.

Alternatively, the yarn may be prepared by wrapping the blended staple fibers around a continuous hydrophobic core to form a sheath. The term “yarn” is utilized herein to encompass any assemblage of the hydrophilic and hydrophobic fibers, in a continuous strand, that can be made into a textile material.

In other words, the term “yarn” as used herein encompasses spun yarns and sheathed filaments, as well as other possible embodiments. The methods for preparing such yarns are well known in the art and need not be repeated here.

/snip/

The yarns of hydrophilic and hydrophobic fibers can be made into a textile material by conventional means such as weaving and knitting. Non-woven fabrics may also be made from the blended fibers. Other fibers may be incorporated into the fabric to obtain desired properties. For example, the fabric may contain about 5 to about 10% of a continuous elastomeric filament (such as Lycra.RTM. elastomer fiber, DuPont Company, Wilmington, Del.), incorporated into the fabric to provide stretch and recovery properties. Due to the enhanced hydrophilic nature, low moisture retention, and rapid drying of the fabrics of this invention, they should be particularly preferred for making active wear garments and thermal underwear.

/snip/

On analyzing data for average skin moisture and the subjects responses regarding comfort, it was determined that perceived skin moisture is highly correlated with measured skin wetness. As shown in FIG. 1, an increase in skin moisture or wetness leads to increasing discomfort.

FIG. 2 shows the differences in comfort for the six different garments as a function of skin wetness. Under dry conditions, the 100% cotton garment is the most comfortable, but, as the body perspires, it rapidly becomes the least comfortable, even more uncomfortable than the “Akwatek”–treated polyester.

The regression lines for the polyester/cotton blends are almost parallel, and fabrics of those blends are more comfortable than cotton as the body begins to perspire. Although differences among the four blends are small, the 10% cotton blend appears to be preferred.

FIG. 3 presents a correlation between comfort and thermal sensation. A close linear relationship exists between comfort and thermal sensation (p<0.001). As a person's body temperature rises (increasing thermal sensation), there is an increase in discomfort.

The four polyester/cotton blends were consistently more comfortable than 100% cotton and “Akwatek”–treated polyester over the whole range of thermal sensations. Of the four blends, the 10 and 15% cotton blends were very close and were perceived as being more comfortable than the 5 and 20% cotton blends.

FIG. 4 presents a correlation between texture and average skin wetness. Ratings of the fabric texture correlate well with measured and perceived skin moisture (p<0.001). Water on the skin from perspiration increases the friction between skin and fabric which leads to the perception that the texture is rough and unpleasant.

The increase in perceived texture roughness is generally slower for the polyester/cotton blends. With increasing skin wetness the regression lines for these cotton blend garments fall below the lines of the “Akwatek”–treated polyester and the 100% cotton.

The 10% cotton blend is perceived as the smoothest of all of the fabrics at all levels of wetness.

/snip/

Consistent with the test results presented in FIGS. 2, 3 and 4, the subjects preferred the garments made of the 85/15 and 90/10 polyester/cotton blends.

/snip/

Full text of patent: http://tinyurl.com/y94tg5
(viewing patent images may require using a free
viewer at http://alternatiff.com).

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United States Patent Application number 20040185728, September 23, 2004,Textiles with high water release rates and methods for making same,inventors: Moore, John W. and Moore, Christopher S., assignee: Optimer, Inc.,

FIELD OF THE INVENTION

The present invention relates to textiles that are treated to enhance performance. More particularly, the present invention relates to textiles that are treated to increase water release rates and reduce drying times.

Even more particularly, the present invention relates to yarns, fabrics, and articles of clothing that are treated with low levels of dispersions which are more hydrophobic than the textile to which they are applied to reduce drying times, reduce spin-dry water contents, increase water release rates, and improve comfort while offering flexibility and minimal added costs to the manufacturing process.

BACKGROUND OF THE INVENTION

During both normal everyday activities and athletic activities, a person desires clothing that is comfortable to wear. A key factor in providing comfort is a garment’s ability to absorb and release perspiration away from the wearer nearly as fast as it is generated by the wearer.

Accordingly, increasing the water release rate of a fabric used in the garment will improve the comfort of the garment. The improved water release rate reduces the drying time after washing or after periods of heavy perspiration.

The drying time of a yarn, fabric, or article of clothing is determined by measuring the amount of time it takes for a yarn, fabric, or article of clothing of a known liquid content to reach its dry weight in known environmental conditions. A more useful measurement for evaluating the ability of a yarn, fabric, or article of clothing to keep the wearer feeling dry is to measure the water release rate of the yarn, fabric, or article of clothing. The water release rate is determined by measuring the change in liquid content of a yarn, fabric, or article of clothing over a fixed time interval.

The water release rate of a given yarn, fabric, or article of clothing will depend on the liquid content of the yarn, fabric, or article of clothing as well as environmental conditions.

The water release rate at or near dryness is representative of a fabric’s ability to keep a person dry during normal use conditions.

Accordingly, a comparison of water release rates at or near dryness of various fabrics is useful in determining which fabric will provide more comfort to the wearer.

Attempts have been made to reduce the drying time of a fabric without reducing the fabric’s overall comfort. For example, Dupont’s CoolMax.RTM. performance fabrics are said to dry faster than other fabrics containing natural or synthetic fibers.

The CoolMax.RTM. fabric, however, requires the use of a synthetic lobed and/or channeled fiber. Accordingly, the fiber must be introduced into the manufacturing process of the yarn to produce CoolMax.RTM. fabrics and garments.

The properties of fabrics and garments also can be altered by treatment of the fiber, yarn, fabric, or garment with an agent providing the desired property. For example, flame retardant, antimicrobial, stain resist, or wetting agents can be added to a fiber, yarn, fabric, or garment. The agent can be added after the garment is manufactured by, for example, adding the agent in a bath form or spraying the agent onto the garment.

U.S. Pat. No. 5,590,420 http://tinyurl.com/y77msv [low friction apparel] discloses an article of clothing treated with low friction materials, such as DuPont’s Teflon.RTM., to reduce the level of friction exhibited by the article of clothing. Most preferably, the level of treatment is incorporated in amounts between 30 and 50% by weight of the treated area, such that the coefficient of friction of the treated material is less than 50% of the coefficient of friction of the untreated material.

U.S. Pat. No. 5,590,420 reports that the addition of low friction material to the fiber, yarn, fabric, or garment can be useful to wick away moisture from the skin. The wicking away of moisture is purported to help guard against irritation, as well as wetness. The wicking away of moisture, however, does not necessarily equate to reduced drying times or improved water release rates.

For example, a garment that wicks quickly may, nonetheless, have a relatively slow drying time and low water release rate. The wicking rate of a fabric is dependent upon capillary forces and is usually considered when a fluid moves along a surface, not away from the surface. The drying time or water release rate depends on the differential forces that attract and repel fluid to or from the surface.

Accordingly, U.S. Pat. No. 5,590,420 does not disclose, teach, or suggest a cost-effective method for improving the water release rates of fibers, yarns, fabrics, or garments

U.S. Pat. No. 5,575,012 http://tinyurl.com/y6f5bq [method for treating legwear and product] discloses a method for treating socks to reduce friction by applying a fluoropolymer. According to U.S. Pat. No. 5,575,012, the socks provide improved comfort to the wearer as a result of the increased sensation of lubricity, not reduced drying times or improved water release rates.

Therefore, a need exists for a garment that will provide increased comfort to the wearer by reducing drying times or increasing water release rates. In addition to improving comfort, there is a need for a fabric that retains less water after completing the spin-dry cycle in a washing machine.

The reduced water content reduces the amount of energy required to dry the fabric. More specifically, there is a need for a fabric that has a faster drying time, lower spin-dry water content, and higher water release rate than conventional fabric. The fabric should be comfortable to wear and offer flexibility and minimize additional costs to the manufacturing process. Preferably, the water release rate of the fabric can be enhanced at any point in the manufacturing process, including before the creation of yarns to after the completion of an article of clothing.

SUMMARY OF THE INVENTION

The present invention provides a textile material having a surface and a discontinuous treatment located on the surface. The discontinuous treatment includes discrete, individual particles that are more hydrophobic than the surface. The discontinuous treatment is in the range of about 0.1% to about 8% by weight of the textile material and increases the water release rate near dryness of said textile material.

Also provided are fabrics having a hydrophilic surface and a discontinuous treatment that is more hydrophobic than the hydrophilic surface.

The discontinuous treatment includes discrete, individual particles located on the hydrophilic surface. The discontinuous treatment is in the range of about 0.1% to about 8% by weight of the fabric and increases the water release rate near dryness of the fabric.

The present invention also provides textile materials having a surface with a discontinuous treatment located on the surface, wherein the discontinuous treatment includes discrete, individual particles of one or more of polyvinyl acetate and a polyvinyl acetate/acrylic copolymer. The discontinuous treatment is present in an amount sufficient to increase the water release rate near dryness of the textile materials.

In certain embodiments, one or more of polytetrafluoroethylene (PTFE), polyvinyl acetate (PVA), and polyvinyl acetate/acrylic copolymer (PVA/a) dispersions are used to treat the textile. Textiles treated with the hydrophobic dispersions exhibit superior drying rates and lower spin-dry water contents. Most surprising, the treated textiles exhibit superior drying properties at very low levels of treatment. By keeping the treatment levels low, the costs of treating the textiles and any negative effects are kept to a minimum.

Also provided are methods for making textiles of the invention. In one aspect, the method includes the step of applying discrete, individual particles of a treatment on a textile surface, wherein the treatment is more hydrophobic than the textile material, the treatment is in the range of about 0.1% to about 8% by weight of the textile material, and the treatment increases the initial water release rate of said textile material.

In other embodiments, the treatment is applied to a fabric or an article of clothing. The variety of methods available for applying the dispersion offers flexibility to the manufacturing process.

The present invention thus introduces textiles and methods for producing textiles that have superior performance characteristics and are cost effective to manufacture. In certain embodiments, the textile is an article of clothing, where the improved water release rate of the treated fabric near dryness helps keep the wearer dry, whether the wearer is vigorously exercising or inactive.

Full text of patent: http://tinyurl.com/y3xuzc
(viewing patent images may require using a free
viewer at http://alternatiff.com).