CN101313094A - Flame and heat resistant stretch fabrics with improved chemical resistance and durability - Google Patents

Abstract

The present invention relates to flame and heat resistant stretch fabrics with improved durability. The stretch fabrics comprise crosslinked polyolefin elastic fibers which may be combined into a core spun yarn with inherently flame resistant fibers. The elastic fibers or yarns can be conveniently formed into fabrics using well-known techniques such as, for example, warp or weft weaving or by using co-knitting techniques with other flame resistant fibers or yarns. Such fabrics are useful in various durable or repeated-use fabric applications such as, but not limited to, clothing (in particular protective garments), and upholstery.

Description

Flame and heat resistant stretch fabric with improved chemical resistance and durability

Background technology and content of the invention

The present invention relates to flame and heat resistant stretch fabrics with improved durability. The stretch fabric comprises cross-linked polyolefin elastic fibers which can be combined with intrinsically flame resistant fibers to form corespun yarns. The elastic fibers or yarns can be conveniently formed into fabrics using known techniques, such as weaving or co-knitting with other flame-resistant fibers or yarns. The fabric is suitable for a variety of durable or reusable fabric applications such as, but not limited to, clothing (especially protective clothing) and upholstery.

Workers in occupations exposed to heat and/or flame hazards, such as foundry workers and chemical and oil refining industry workers, wear protective clothing to minimize the possibility of severe burns or other bodily injury. In attempting to provide these workers with maximum protection against heat and fire, the prior art has emphasized the use of heat and/or flame resistant fabrics to form protective clothing. Flame resistant fabrics suitable for these garments are usually made from woven intrinsically flame resistant yarns, which tend to be heavy and rigid. As a result, garments made therefrom tend to be heavy, bulky and somewhat inflexible. The rigidity and general inflexibility of these fabrics tend to limit the movement of workers wearing garments made from these fabrics.

Attempts have been made in the prior art to develop garments which are protective against exposure to extreme heat and fire, but which are flexible so as to allow greater freedom of movement for the wearer. One approach is to use conventional, heavy, somewhat inflexible flame-retardant fabrics for the majority of the garment, and lighter, less flame- and heat-resistant materials for the seams of the garment. For example, U.S. Patent No. 4,922,552 discloses a firefighter's garment formed from a thick layer of flame-retardant fabric, wherein the outer layer of the protective flame-retardant material has been partially cut away from it, and the flame-retardant and protective properties are significantly improved. A poorer layer of lighter material takes its place, but with greater flexibility and less bulk. The problem with this garment is that the flexibility of the garment is limited to certain parts of the garment, and some flame protection is sacrificed for flexibility.

More recently, US Patent No. 5,527,597 proposes the use of elastic fibers such as spandex or rubber to make protective clothing more flexible. This reference teaches that since elastic corespun yarns have low heat resistance and/or flame resistance, they require protective yarns such as fibers made from aramid/polybenzimidazole (PBI) blends winding. Wrap fibers are designed to protect the elastic corespun yarn from direct exposure to heat and fire that would otherwise cause the corespun yarn to degrade or melt. However, this reference acknowledges that the protective wrap will not fully protect the elastic fibers (especially when subjected to stretching) and that the elastic yarns will eventually break. This is especially true when clothes are exposed to high temperatures for relatively long periods of time, such as during industrial laundering of clothes.

Another method of making fabrics flame resistant involves chemically treating fabrics that are otherwise not flame resistant. It is generally believed that the fabric of intrinsic flame retardant fiber has a longer lasting protection time; while it is generally believed that the chemically treated fabric (such as flame retardant cotton) has a shorter lasting protection time, but is more comfortable for the wearer. Furthermore, the chemical treatments used in this process are often too harsh on the elastic fibers to withstand, resulting in a rapid loss of elasticity or even breakage.

Therefore, there remains a need for a more comfortable elastic heat and/or flame resistant fabric that is durable after repeated exposure to industrial laundering. The present invention relates to such fabrics. The fabric is elastic, flame and/or heat resistant, and durable, making it particularly suitable for these applications.

A material is typically characterized as elastic if it has a high percentage of elastic recovery (ie, a low percentage of permanent set) after application of a biasing force. Ideally, elastic materials are characterized by a combination of three important properties, namely, (i) a low percentage of permanent set, (ii) low stress-strain or load-strain, and (iii) low percentage of stress-relaxation or load-relaxation. In other words, there should be (i) stretching the material requiring low stress or load, (ii) no or low stress or unloading relaxation once the material is stretched, and (iii) after cessation of stretching, biasing or straining, Full or height return to original size.

In order to be useful in the elastic, durable, flame-resistant and/or heat-resistant fabrics of the present invention, the fibers from which the fabrics are made must be stable under, inter alia, dyeing and heat-setting treatments as well as industrial laundering conditions. For an elastic polyolefin fiber to be stable under dyeing and heat setting conditions, it must be crosslinked. These fibers can be crosslinked by one or more of a number of different methods, e.g., e-beam or UV radiation, silane or azide treatment, peroxide, etc. better than other methods. For example, polyolefin fibers irradiated in an inert atmosphere (as opposed to irradiated in air) tend to be highly stable during dyeing (ie, the fibers do not melt or fuse together). At higher temperatures, such as those encountered in some heat-setting steps (e.g., 200-210°C for polyethylene terephthalate (PET) fibers), the addition of hindered phenol and hindered amine stabilizers The mixture further stabilizes these fibers.

Spandex (also known as elastane), a segmented polyurethane elastic material, is currently being used in a variety of stretch fabrics, including flame and heat resistant fabrics (see US 5,527,597). However, spandex fibers and some auxiliary fibers are unstable at the usual high heat setting temperatures, and spandex fibers tend to lose their integrity when subjected to high service temperatures (such as those encountered during washing, drying, and ironing) , shape and elastic properties.

It has been discovered that elastic flame resistant and/or heat resistant fabrics can be produced which survive exposures where other flame resistant and/or heat resistant fabrics cannot. In particular, the fabrics of the present invention are durable, which means that the fabric can withstand c) 50 industrial laundering cycles at at least 65°C, where "survived" means that the treated fabric exhibits less than about 20% Growth, preferably less than about 10%, more preferably less than about 8%.

Detailed ways

The following terms have the meanings indicated when used in this patent application:

"Fiber" means a material having a length to diameter ratio greater than about 10. Fiber is usually classified according to its diameter. Filament fibers are generally defined as fibers having a single fiber diameter greater than about 15 denier, usually greater than about 30 denier. Fine fibers generally refer to fibers having a diameter of less than about 15 denier. Microdenier fibers are generally defined as fibers having a diameter of less than about 100 microdenier.

"Filament filament" or "monofilament fiber" in contrast to "staple fibers" (that is, tows that have been cut or otherwise divided into segments of predetermined lengths) of discrete tow material of defined length. Refers to a single, continuous tow material of indeterminate (ie, not predetermined) length.

The term "flame retardant" applied to fabrics or articles means that the fabric or article exhibits 1) a reaction to flame propagation when directly exposed to flame, as specified in DIN EN 531:02.95 guidelines (DIN ISO15025:02.03 standard test method) Belonging to class A; 2) heat transfer when exposed to flame, according to DIN EN 531: 02.95 guideline specification (DIN EN 367: 11.92 standard test method) belonging to class B1 or higher (B2, B3, B4 or B5); 3 ) for heat transfer when exposed to radiant heat, according to DIN EN 531:02.95 guideline specification (DIN EN 366:05.93 standard test method) of class C1 or higher (C2, C3 or C4). Fabrics or products that can meet or partially meet these requirements are in accordance with the ISO 2801:1998 international standard "Clothing for protection against heat and flame-General recommendation for selection, care and use of protective clothing (heat-resistant and flame-resistant clothing - protective clothing selection, preservation and general recommended practice for use)", considered suitable for at least "low risk level: localized exposure to heat and/or fire" protective clothing.

The term "durable" as applied to a fabric or article means that the fabric or article exhibits durability in both the warp and weft directions after 50 cycles of industrial laundering at a temperature of at least 65°C, or at least 75°C, 85°C or even 95°C. An increase of less than 20%, preferably less than about 10%, more preferably an increase of less than about 8%, 6% or even 5%.

The term "growth" refers to the residual elongation of a fabric, or the amount of elongation of a fabric, expressed as a percentage of the original fabric dimension, after a load has been applied and allowed to recover over a period of time. Growth was determined using ASTM D3107.

"Elastic fiber" means that the fiber will recover at least about 50%, more preferably at least about 60%, and still more 70% is preferred. A suitable way to carry out this test is based on the International Bureau for Standardization of Manmade Fibers, BISFA 1998, chapter 7, option A). In this test, fibers are placed between grips 4 inches apart, and the grips are pulled apart to 8 inches apart at a rate of about 20 inches per minute, followed by immediate recovery. Preferably, the elastic textile articles of the present invention have a high percentage of elastic recovery (ie, a low percentage of permanent set) after application of a biasing force. Ideally, elastic materials are characterized by a combination of three important properties, namely, (i) low stress-strain or load-strain; (ii) low percent stress relaxation or load relaxation; and (iii) low percent permanent set. In other words, there should be (i) stretching the material requiring low stress or load, (ii) zero or low stress or unloading relaxation once the material is stretched, and (iii) after cessation of stretching, biasing or straining, Full or height return to original size.

"Elastomeric material" is also referred to as "elastomer" and "elastomeric" in the prior art. For the purposes of the present invention, "elastic article" means an article comprising elastic fibers.

"Non-elastomeric material" means a material, such as a fiber, that does not have elasticity as defined above.

"Core spun yarn" means a yarn of fiber twisted around a core yarn, which is another filament fiber or a previously spun yarn, thereby at least partially covering the core yarn.

One aspect of the invention is an elastic, durable, flame-resistant and/or heat-resistant article, such as a fabric or assembled garment comprising heat-resistant, cross-linked elastic fibers. The fabric can be rendered flame and/or heat resistant by incorporation with intrinsically flame retardant materials, and/or the article can be chemically treated to render it heat and/or flame resistant.

In one embodiment, the article is a durable stretch fabric prepared and processed from one or more crosslinked, heat resistant olefin elastic fibers. The fabric may be prepared by any method, eg, weaving, knitting, etc., and may be made from a combination of elastic and inelastic ("stiff") fibers. These fabrics exhibit excellent chemical resistance (eg, chlorine resistance) and durability, eg, they retain their shape and feel ("hand") after repeated exposure to usage conditions such as washing, drying, etc. The fabric or garment exhibits no greater than about 10% change in elasticity, and/or maintains no greater than about 50% growth, more preferably no greater than An increase of about 20%, more preferably an increase of no greater than about 10%, and most preferably an increase of no greater than about 8%.

The elastic fibers are preferably cross-linked, heat-resistant olefin elastic fibers. These fibers include ethylene polymers, propylene polymers and perhydrogenated styrene block copolymers (also known as catalytically modified polymers). The ethylene polymers include homogeneously branched and substantially linear homogeneously branched ethylene polymers, as well as ethylene-styrene interpolymers. Most preferably homogeneously branched and substantially linear homogeneously branched ethylene polymers are crosslinked.

The elastic fibers of the present invention may have any suitable fiber diameter, for example, 15, 40, 70, 140 denier or higher.

Suitable elastic fibers for use in the present invention are disclosed in US 6,437,014, the entire contents of which are incorporated herein by reference. As described in this reference, the fibers can be produced by a number of methods known in the art, such as meltblown fibers, spunbond fibers or, more preferably, by melt spinning. Likewise, as taught in US 6,437,014, the fibers can be made from many different materials including ethylene-alpha olefin interpolymers, substantially hydrogenated block polymers, styrene butadiene styrene block polymers, styrene- Ethylene/butylene-styrene block polymers, ethylene-styrene interpolymers, polypropylene, polyamides, polyurethanes, and combinations thereof. The crosslinked homogeneously branched ethylene polymers described in this reference, especially the substantially linear ethylene polymers, are especially useful in preparing the articles of the present invention.

These elastic fibers can be used purely or can be advantageously used as the core yarn of the core yarn. Corespun yarns are easier to process on some commercial weaving or knitting machines. Additionally, the overall flame and/or heat resistance of the corespun yarn (and articles comprising the yarn) can be enhanced by selecting an intrinsically flame retardant material for use as the wrap fiber of the corespun yarn. Suitable fiber materials for wrapping the elastic core yarn include polyamides (including aramids), polynosic rayon, cellulose (especially flame retardant cellulose), polyester (especially flame retardant polyester ), polyvinyl alcohol, polytetrafluoroethylene, wool (especially flame retardant wool), polyvinyl chloride, polyether ether ketone, polyetherinide, polyolefin, polyamide imide (polyimideamide), Polybenzoxazole, carbon, modified acrylic acrylic, melamine, glass, polybenzimidazole (PBI) fiber, polyphenylene sulfide PPS fiber, polyacrylate, semicarbon, phenolic Phenolic or novoloid fibers, modified acrylics, chlorofibres, FR viscose, nylon and acrylic, and combinations thereof. Aramid fibers are particularly preferred because of their flame retardancy.

These fibers, whether used purely or more preferably as the core yarn of a core yarn, are preferably used with other fibers or yarns in a weaving or knitting process to make the fabrics of the present invention. In order to increase the flame resistance of the article, it may be advantageous to combine elastic fibers or corespun yarns with intrinsically flame resistant fibers. Suitable fiber materials for use in combination with the elastic fibers or yarns include those listed above for use as covering fibers in corespun yarns. Aramid fibers are particularly preferred because of their intrinsic flame retardancy. Typically, cross-linked, heat-resistant olefinic elastic fibers constitute only a minority by weight of the fabric, and the precise percentage of each fiber can be optimized for any particular application. Typically, the fabric contains at least about 2% elastane by weight, with woven fabrics often having less than about 15% elastane by weight and knitted fabrics up to about 35% elastane by weight, although amounts within these ranges are possible outside.

It is also desirable to include static dissipating fibers, such as metal or carbon fibers, in the fabric. Clothing comprising this static dissipative fiber will provide additional protection to workers.

The fabrics of the invention can be produced according to known manufacturing methods, such as weaving or knitting. One of ordinary skill in the art will understand that, generally for any given fabric composition, the denser the fabric structure, the better the flame resistance of the fabric. But at the same time, the denser the fabric, the heavier the fabric, which will make the clothes made from it less comfortable.

The fabrics of the present invention can be used to make garments. Examples of garments which may advantageously be made from the fabrics of the invention include uniforms, especially uniforms which are subject to industrial ironing.

The fabrics of the present invention include fabrics known to require harsh and severe processing using chemicals and conditions that degrade most conventional stretch fabrics because these chemicals and conditions degrade the spandex component of these fabrics. However, the fabrics of the present invention comprise elastane fibers that are particularly resistant to such degradation, and thus fabrics comprising these fibers exhibit surprising durability and chemical resistance.

In another embodiment of the present invention, the elastic fibers may be chemically treated to impart flame retardancy. In this method, the fibers or articles are treated with special chemicals to render them flame retardant. These chemicals are known in the art and include 4-hydroxymethylphosphonium salts (hereinafter designated THP salts), such as THPS, which are very effective for imparting flame retardancy to cellulosic materials. These chemicals can be applied using ammonia-insoluble THP/urea precondensate salts or using the THP/pad/dry/cure process or both. While any known method of imparting flame retardancy may be used, exemplary techniques are described in US Patent Nos. 4,494,951, 4,078,101, and 5,238,464. Treatments to improve the heat resistance of wool-based fabrics are also known by adding hexafluorotitanates and hexafluorozirconates to the wool fibres, which enter the wool at or below the boiling point. The treatment was like the Zirpro finishing technology commercialized by the International Wool Bureau (IWS).

The chemical treatments commonly used to impart flame resistance expose the fibers to harsh environments which degrade most elastane fibers. However, preferred melt-spun fibers comprising cross-linked homogeneously branched ethylene polymers are resistant to degradation even under the harsh conditions typically seen in these processes. It is envisioned that the treatment can be applied to fibers, fabrics and even the desired finished product.

It is also possible to combine techniques for making flame-resistant and/or heat-resistant durable stretch fabrics, such as utilizing chemical treatments of fabrics made from inherently flame-resistant and/or heat-resistant fibers.

The following examples serve to illustrate the invention, but do not limit it. Ratios, parts and percentages are by weight unless otherwise indicated.

Example

Fiber Description:

The core yarn is produced by the Siro spinning method. The corespun yarn comprised 91% by weight polyamide-imide fibers; 1% by weight carbon fibers and 8% by weight 140 denier crosslinked ethylene-octene copolymer fibers (Dow XLA fibers from The Dow Chemical Company) produced fibers. An intimate mix of polyamide-imide fibers and short (cotton-like) fiber lengths of carbon fibers is spun using a conventional ring spinning frame, with 140 denier ethylene-octene copolymer during twisting Combined, the pre-draw ratio is 5.2:1 (draw). This spinning method results in the formation of a corespun yarn with an average yarn count of Nm 1/26 in which ethylene-octene copolymer of 140 denier 5.2X draft constitutes the core yarn and polyamide-imide fibers and carbon fibers constitute the outer sheath layer. Cohesion was imparted to the sheath fibers by applying a twist of 570 twists per meter.

The fabric is then woven using the corespun yarn as the weft component. A similar yarn was used as the warp component, the yarn count being Nm 1/26 based on 99% by weight polyamide-imide fibers and 1% by weight short (cotton-like) fiber length carbon fibers. The settings of the loom are: the total number of warps is 4867, the reed width is 201 cm, and the number of wefts per meter of weft is 2550.

The fabric thus woven is then subjected to relaxation finishing in open width in order to promote weft shrinkage and allow for the required extensibility. The fabric is then subjected to the following flame retardant tests:

1) Response to flame propagation when directly exposed to flame, in accordance with DIN EN531: 02.95 guidelines (DIN ISO 15025: 02.03 standard test method): the result is grade A;

2) Heat transfer when exposed to flame, in accordance with DIN EN 531: 02.95 guidelines (DINEN 367: 11.92 standard test method): the result is B1 level;

3) Heat transfer when exposed to radiant heat, according to DIN EN 531: 02.95 guidelines (DIN EN 366: 05.93 standard test method): the result is class C1.

Elasticity is tested using the TTM074 DuPont method (total elongation of woven fabrics) known in the art; while growth is tested using the TTM077 DuPont method (percent growth of stretch woven fabrics) known in the art. The growth and elongation on the fabric in this example was: 10% elongation, 4.0% growth after 1 minute, 3.2% growth after 1 hour.

These fabrics exhibit similar durability to the fabrics reported in WO 03/078723A1 (herein incorporated by reference in its entirety), especially the fabrics described in Example 5 "Laundering".

While the invention has been described in some detail through the foregoing embodiments, such detail is for purposes of illustration. Many changes and modifications may be made to the present invention without departing from the spirit and scope of the invention as described in the claims. All references, including patents and patent applications, cited above are hereby incorporated by reference.

Claims (21)

1, the preparation method of the fire-retardant or heat-resisting goods of a kind of durable elastic force, this method comprise the steps: a) to select to comprise the elastomer of cross-linked polyolefin; And b) with step (a) thus described fiber combine with one or more essential fire resistance fibres the preparation goods.

2, method according to claim 1, wherein, described cross-linked polyolefin is the ethene polymers of crosslinked even branching.

3, method according to claim 1, wherein, the ethene polymers of described crosslinked even branching is at the preceding heart yarn as cladded yarn of step (b).

4, method according to claim 3, wherein, it is to have the fire-retardant and/or stable on heating fiber of essence that the skin of described cladded yarn coats.

5, method according to claim 4, wherein, described skin comprises polyamide fiber.

6, method according to claim 5, wherein, described polyamide fiber is an aramid fibre.

7, method according to claim 1, wherein, the essential fire resistance fibre of described step (b) comprises polyamide fiber.

8, method according to claim 1, wherein, the essential fire resistance fibre of described step (b) comprises aramid fibre.

9, method according to claim 1, wherein, described step (b) further comprises with the quiescent dissipation fiber and combining.

10, the fire-retardant and/or heat-resisting goods of a kind of durable elastic, described goods comprise elastomer and the essential fire resistance fibre that contains cross-linked polyolefin.

11, goods according to claim 10, wherein, described cross-linked polyolefin is the ethene polymers of even branching.

12, goods according to claim 10 is characterized in that: described goods after 50 circulations of industry laundering, show the growth less than 20% under at least about 65 ℃.

13, goods according to claim 12, wherein, described growth is less than 10%.

14, goods according to claim 13, wherein, described growth is less than 8%.

15, goods according to claim 10, wherein, described goods are woven or knit goods.

16, a kind of clothes of making by the described fabric of claim 15.

17, goods according to claim 10, wherein, described essential fire resistance fibre comprises polyamide fiber.

18, goods according to claim 10, it further comprises the quiescent dissipation fiber.

19, goods according to claim 18, wherein, described quiescent dissipation fiber is metal or carbon fiber.

20, goods according to claim 10, wherein, described goods show at least a in the following test: a) when directly being exposed to flame for the reaction of flame propagation, according to DIN EN 531:02.95 criterion standard (DIN ISO15025:02.03 standard testing method), belong to the A level; Conductivity of heat when b) being exposed to flame belongs to B1 level or more senior (B2, B3, B4 or B5) according to DIN EN 531:02.95 criterion standard (DINEN 367:11.92 standard testing method); Or c) conductivity of heat when being exposed to radiant heat belongs to C1 level or more senior (C2, C3 or C4) according to DIN EN 531:02.95 criterion standard (DIN EN366:05.93 standard testing method).

21, goods according to claim 20, wherein, described goods satisfy all test requests.