KR20060124761A - Modacrylic/cotton/aramid fiber blends for arc and flame protection - Google Patents

Abstract

Yarns, fabrics and garments suitable for use in arc and flame protection contain modacrylic, cotton and aramid fibers.

Description

Modacrylic / Cotton / Aramid Fiber Blends for Arc and Flame Protection}

The present invention relates to blended yarns useful in the manufacture of fabrics having arc and flame protective properties. The invention also relates to garments made of such fabrics.

Personnel working near live electrical installations and emergency personnel responding to events near the electrical installation are exposed to the risk of electric arcs and flames that may result from an arcing event. Electric arcs are very extreme phenomena that typically involve thousands of volts and thousands of amps of electricity. Electric arcs are formed in air when the potential difference (ie, voltage) between two electrodes ionizes atoms in the air to allow electricity to pass through.

Arc protective and flame retardant garments are typically inconvenient to wear because of the incorporation of protective fibers with poor water vapor permeability. Persons wearing protective clothing typically experience both unpleasant touch and heat stress due to protective fibers incorporated in protective clothing.

U.S. Patent No. 5,208,105 to Ichibori et al. Discloses a flame retardant composite fiber blend comprising a halogen containing fiber having a large amount of antimony compound, and one or more fibers selected from a series of fibers consisting of natural and chemical fibers. After being woven into the fabric, this fiber blend was tested against its limited oxygen index (Limited Oxygen Index).

Green U.S. Patent No. 5,223,334 discloses a fabric that protects against radiant energy from an electric arc. Green did not disclose the use of Modacrylic fibers in blended yarns. In addition, green has not disclosed a protective fabric formed of yarn comprising less than 50% cotton.

What is needed are threads, fabrics and garments that provide a high level of protection and flame retardancy upon exposure to electric arcs to protect the wearer from secondary effects.

Summary of the Invention

The present invention

(a) 40 to 75% by weight of modacryl fiber,

(b) 10 to 40% by weight of cotton fibers and

(c) 1 to 25% by weight of aramid fibers

(The above weight percentages are based on components (a), (b) and (c).)

It relates to a thread for use in arc and heat protective fabrics and garments comprising a.

Such yarns are usefully incorporated in thermal and arc resistant fabrics that are particularly suitable for protecting workers from electric arcs. Furthermore, the fabrics and garments can provide resistance to breakopen, flame and abrasion.

The present invention relates to the provision of threads, fabrics and garments to provide both improved arc protection and flame retardancy. Fabrics and garments comprising flame retardant fibers with low tensile strength are ruptured by incident energy upon exposure to the intense thermal stress of the electric arc, exposing the wearer to further injury. Electric arcs typically involve currents of thousands of volts and thousands of amps. Electric arcs are much more powerful than the incident energy, for example from a flash fire. To protect the wearer, clothing and fabrics must resist the passage of energy to the wearer. It is believed that this is done both by the fabric absorbing some of the incident energy and by the fabric resisting rupture. Upon rupture, holes are formed in the fabric, exposing the surface or wearer directly to incident energy.

The threads, fabrics and garments of the present invention resist the transfer of energy upon exposure to the intense thermal stress of an electric arc. It is believed that the present invention absorbs some of the incident energy to reduce energy transfer and to reduce the energy transmitted by charring.

The yarns of the present invention comprise blends of modacryl fibers, cotton fibers and aramid fibers. Typically, the yarns of the present invention comprise 40 to 75 weight percent modacryl fiber, 10 to 40 weight percent cotton fiber and 1 to 40 weight percent aramid fiber. Preferably, the yarn of the present invention comprises 45 to 65% by weight of modacryl fiber, 15 to 35% by weight of cotton fiber and 5 to 30% by weight of aramid fiber. The weight percentages are based on the three components.

"Thread" means a collection of fibers spun together or twisted together to form continuous strands that can be used in weaving, knitting, braiding, or plaiting or otherwise produced into textiles or fabrics. .

Modacrylic fibers refer to acrylic synthetic fibers made primarily from polymers comprising acrylonitrile. Preferably, the polymer is a copolymer comprising 30 to 70% by weight of acrylonitrile and 70 to 30% by weight of halogen containing vinyl monomers. Halogen containing vinyl monomers are for example one or more monomers selected from vinyl chloride, vinylidene chloride, vinyl bromide, vinylidene bromide and the like. Examples of vinyl monomers that can be copolymerized are acrylic acid, methacrylic acid, salts or esters of these acids, acrylamide, methacrylamide, vinyl acetate and the like.

Preferred modacryl fibers of the present invention are copolymers of vinylidene chloride and acrylonitrile, further having antimony oxide or antimony oxides for improving flame retardancy. Such useful modacrylic fibers are fibers having 2% by weight of antimony trioxide, disclosed in US Pat. No. 3,193,602, various oxidations present in amounts of at least 2% and preferably up to 8% by weight, as disclosed in US Pat. No. 3,748,302. Fibers made of antimony, including, but not limited to, fibers having 8 to 40 weight percent antimony compound, disclosed in US Pat. Nos. 5,208,105 and 5,506,402.

In the yarns of the present invention, the modacryl fiber provides flame retardant char forming fibers with typically LOIs of 28 or more depending on the level of doping of the antimony derivative. Modacrylic fibers also prevent the expansion of fiber damage due to exposure to flame. Modacrylic fibers are highly flame retardant but by themselves do not provide sufficient strength to the yarn or fabric made from the yarn to provide the desired level of burst resistance upon exposure to an electric arc.

As used herein, "aramid" means polyamide in which at least 85% of the amide (-CONH-) bonds are bonded directly to two aromatic rings. Additives may be used for the aramid, and in practice, up to 10% by weight of other polymeric materials may be mixed with the aramid, the diamine of the aramid may be replaced by up to 10% of other diamines, or the diacid chloride of the aramid with up to 10% of other diacid chlorides. It has been found that substituted copolymers can be used. Suitable aramid fibers are described in Man-Made Fibers-Science and Technology, Volume 2, Section titled Fiber-Forming Aromatic Polyamides, page 297, W. Black et al., Interscience Publishers, 1968. Aramid fibers are also disclosed in US Pat. Nos. 4,172,938, 3,869,429, 3,819,587, 3,673,143, 3,354,127, and 3,094,511. m-aramid is aramid with amide bonds in meta position relative to each other, and p-aramid is aramid with amide bonds in para position relative to each other. In the practice of the present invention, the most commonly used aramids are poly (paraphenylene terephthalamide) and poly (methphenylene isophthalamide).

Within the scope of the present invention, a single kind of aramid fiber can be used. By way of example, either meta-aramid or para-aramid fibers can be used.

However, a preferred embodiment is the use of both para-aramid and meta-aramid fibers. Exemplary percent contents are 20 to 40% by weight of para-aramid fibers and 60 to 80% by weight of meta-aramid fibers. The percentage content is based on aramid only. The preferred range of the two aramids is from 25 to 35% by weight of para-aramid and from 65 to 75% by weight of meta-aramid.

In the yarns of the invention, the cotton fibers provide flame retardant fibers that carry moisture through the yarns. Garments comprising cotton fibers draw moisture away from the wearer to enhance wearer comfort. By sucking up the sweat away, the thermal stress on the wearer who is exercising is reduced.

In addition, antistatic components such as steel fibers, carbon fibers, or carbon coatings may be added to the yarns, fabrics or garments of the present invention. The conductivity of metals such as carbon or steel, when incorporated into the yarns, fabrics or garments of the present invention, provides electrical conduits to help dissipate accumulated static electricity. Electrostatic discharges can be dangerous for workers using sensitive electrical equipment or working near flammable vapors.

The yarns of the present invention include, but are not limited to, ring spinning, core spinning, and air jet spinning or more advanced air spinning techniques such as Murata Air Jet Spinning, which uses air to twist staple fibers into yarn. It can be prepared by any practical spinning technique commonly known in the art. Typically, single yarns made by any conventional technique are spun together to form a plywood comprising two or more single yarns and then converted to a fabric.

In order to protect against the intense thermal stresses caused by electric arcs, arc protective fabrics and garments formed from such fabrics may have a short char length indicating slow development of fabric damage, LOI higher than oxygen concentration in the air for flame retardancy (char length), and good rupture resistance that prevents the incident energy from directly hitting the surface below the protective layer.

Thermal protective clothing, such as firefighter's protective clothing, typically provides protection against convective heat generated by open flames. Such protective clothing may rupture (i.e., puncture the fabric) upon exposure to the strong energy generated by the electric arc, causing the energy to penetrate the garment and cause severe damage to the wearer. The fabric of the present invention provides both protection against convective heat of open flames and resistance to bursting and energy transfer upon exposure to electric arcs. The fabric thickness and overall weight of protective clothing commonly worn, such as fireman's protective clothing, can cause heat stress to the wearer by keeping body heat and sweat close to the skin. The fabric of the present invention includes moisture-carrying fibers, such as cotton, inside the yarn of the fabric to draw moisture away from the sweat away from the wearer to provide a means of improving fit and reducing thermal stress.

Basis weight is a measure of fabric weight per unit area. Typical units are ounces per square yard and grams per square centimeter. Base weights reported herein are given in ounces per square yard (OPSY). As the amount of fabric per unit area increases, the amount of material between the potential hazard and the protected object increases. An increase in the basis weight of the material suggests that a corresponding increase in protective performance will be observed. Increasing the basis weight of the fabrics of the present invention results in an increase in burst resistance, an increase in thermal protection index, and an increase in arc protection. The basis weight of the fabric of the invention is typically greater than about 8.0 opsy, preferably greater than about 8.7 opsy, most preferably greater than about 9.5 opsy. If the basis weight of the fabric of the present invention exceeds 12 opsy, the stiffness will be increased to reduce the fit of the garment made of the fabric.

Char length is a measure of the flame retardancy of textiles. Char is defined as a carbonaceous residue formed as a result of pyrolysis or incomplete combustion. The char length of the fabric under ASTM 6413-99 test conditions as reported herein is defined as the distance from the fabric end exposed directly to the flame to the furthest point where fabric damage is observed after applying a certain tear force. Preferably, the char length of the fabric of the present invention is less than 6 inches, preferably less than 4.5 inches.

The fabric of the invention can be used as a single layer or as part of a multilayer protective garment. The yarns of the present invention may be present on the warp or weft of the fabric. Preferably, the yarn of the present invention is present in both warp and weft of the resulting fabric.

Test method

Abrasion test

The wear performance of the present invention was measured according to ASTM D-3884-01 ("Standard Guide for Abrasion Resistance of Textile Fabrics (Rotary Platform, Double Head Method)").

Arc resistance test

The arc resistance of the fabric of the present invention was measured according to ASTM F-1959-99 ("Standard Test Method for Determining the Arc Thermal Performance Value of Materials for Clothing"). Preferably, the arc resistance of the fabric of the present invention is at least 0.8 cal / cm 2 / opsy, more preferably at least 1.2 cal / cm 2 / opsy.

Grab Test

Grab resistance of the fabric of the present invention was measured according to ASTM D-5034-95 ("Standard Test Method for Breaking Strength and Elongation of Fabrics (Grab Test)").

Limit Oxygen Index Test

The limit oxygen index (LOI) of the fabric of the present invention was measured according to ASTM G-125-00 ("Standard Test Method for Measuring Liquid and Solid Material Fire Limits in Gaseous Oxidants").

Tear test

Tear resistance of the fabric of the present invention was measured according to ASTM D-5587-03 ("Standard Test Method for Tearing of Fabrics by Trapezoid Procedure").

Thermal protection performance test

The thermal protection performance of the fabrics of the present invention was measured according to NFPA 2112 ("Standard on Flame Resistant Garments for Protection of Industrial Personnel Against Flash Fire").

Vertical flame test

The char length of the fabric of the present invention was measured according to ASTM D-6413-99 ("Standard Test Method for Flame Resistance of Textiles (Vertical Method)").

The term thermal protective performance (or TPP) relates to the ability of the fabric to provide continuous and reliable protection for the wearer's skin under the fabric when exposed to direct flame or radiant heat.

Limit Oxygen Index (LOI) according to ASTM G125 / D2863

Minimum concentration of oxygen, expressed as a percentage by volume of oxygen and nitrogen mixture, that will support the burning combustion of materials started at room temperature under the conditions of ASTM D2863.

The following examples are provided to illustrate the invention. Unless stated otherwise, all parts and percentages are by weight and temperatures are in degrees Celsius.

Modacrylic / Cotton / Aramid Fabric

Example 1

Both warp and weft yarns produced a comfortable and durable fabric, a ring spun yarn composed of Nomex® type 462, Kevlar® 29, an intimate blend of modacryl and cotton. NOMEX® Type 462 is 93% poly (m-phenylene isophthalamide) (MPD-I), 5% poly (p-phenylene terephthalamide) (PPD-T), and electrostatic dispersion fibers (DuPont) P-140) 2%, modacryl is ACN / polyvinylidene chloride copolymer with 15% antimony (known as Protex®M), and Kevlar® 29 is poly (p-phenylene terephthalate) Amide) (PPD-T).

A conventional cotton system produces a picker blend sliver with 10% by weight Nomex® Type 462, 10% by weight Kevlar® 29, 55% by weight of modacryl, and 25% by weight of a cotton, It was processed into a spun yarn with a twist constant of 3.7. The yarn thus produced was a single yarn of 24.6 tex (24 cotton number). Then, two single yarns were plyed together in a plywood machine to prepare two plywood yarns. Using a similar process and the same twist and blend rate, 32.8 tex (18 face number) yarns were prepared and used as weft yarns. Subsequently, this yarn was double braided to prepare a braided yarn.

Nomex® / Kevlar® / modacryl / cotton yarn was used as the warp and weft of the 3 × 1 twill structure in the loom. The greige twill had a structure of 24 warp yarns per cm and 15 weft yarns (60 warp yarns per inch, 39 weft yarns) and had a basis weight of 271.3 g / m 2 (8 oz / yd ² ). The raw twill fabric prepared as above was refined in hot water and dried under storage capacity. The refined fabric was then jet dyed with a basic dye.

Example 2

Both warp and weft yarns produced a comfortable and durable fabric, a ring yarn composed of an intimate blend of Nomex® type 462, Kevlar® 29, modacryl and cotton. NOMEX® Type 462 is 93% poly (m-phenylene isophthalamide) (MPD-I), 5% poly (p-phenylene terephthalamide) (PPD-T), and electrostatic dispersion fibers (P- from DuPont) 140) 2%, modacryl is ACN / polyvinylidene chloride copolymer (known as Protex®M) with 15% antimony, and Kevlar® 29 is poly (p-phenylene terephthalamide) (PPD-T )to be.

A conventional cotton system produces a picker blend sliver with 10% by weight of NOMEX® Type 462, 10% by weight of Kevlar® 29, 45% by weight of modacryl, and 35% by weight of cotton, and twisted using a ring spinning machine It was processed into a yarn of constant 3.7. The yarn thus produced was a single yarn of 24.6 tex (24 cotton number). Subsequently, two single yarns were spliced together in a fusing machine to prepare two flies. Using a similar process and the same twist, a 32.8 tex (18 face number) yarn was made with a Nomex®462 / modacryl blend of 50/50 ratio and used as weft yarn. Subsequently, this yarn was double brazed to prepare a braided yarn.

Nomex® / Kevlar® / modacryl / cotton thread was used as a weft yarn with a 3 × 1 twill structure in a loom weaving machine, and Nomex® / modacryl thread was used as the weft yarn. The raw twill had a structure of 23 warp yarns per cm, 16 weft yarns (58 warp yarns per inch, 40 weft yarns) and a basis weight of 264.5 g / m 2 (7.8 oz / yd ² ). The raw twill fabric prepared as above was refined in hot water and dried under storage capacity. The refined fabric was then jet dyed with a basic dye.

The table below shows the measured properties of Examples 1 and 2.

Example 1 Example 2 Fabric composition Fabric structure 2 × 1 twill 2 × 1 twill Basis weight (opsy) 6.7 6.7 Char Length (in) Slope × Weft 4 × 4 3.3 × 3.6 TPP value (cal / cm 2) 11.8 12.5 Grab Strength (lbf) Slope × Weft 100 × 96 118 × 89 Trap Tear (lbf) Slope × Weft 13.6 × 11.7 13.8 × 10.8 Taber Abrasion (cycles) CS-10 / 1000 g 352 317

Claims (20)

(a) 40 to 75% by weight of modacryl fiber, (b) 10 to 40% by weight of cotton fibers and (c) 1 to 40% by weight of aramid fibers (The above weight percentages are based on components (a), (b) and (c).) Comprising a seal suitable for providing arc and flame protection. The method of claim 1, (a) 45 to 60% by weight of modacryl fiber, (b) 15 to 35 weight percent of cotton fibers and (c) 5 to 30% by weight of aramid fibers Thread containing. The yarn of claim 1 wherein the fiber comprises both para-aramid and meta-aramid fibers. The yarn of claim 3 wherein the para-aramid fibers are present in the range of 20 to 40 weight percent and the meta-aramid fibers are in the range of 60 to 80 weight percent, based on the total aramid fibers. The yarn of claim 4 wherein the para-aramid fiber is present in the range of 25 to 35 weight percent and the meta-aramid fiber is present in the range of 65 to 75 weight percent. 6. The yarn of claim 5 further comprising an antistatic component. The yarn of claim 6 wherein the antistatic component is carbon or metal. 8. The yarn of claim 7, wherein the antistatic component is carbon. The yarn of claim 1 further comprising an antistatic component. 10. The yarn of claim 9 wherein the antistatic component is carbon. (a) 40 to 75% by weight of modacryl fiber, (b) 10 to 40% by weight of cotton fibers and (c) 1 to 40% by weight of aramid fibers (The above weight percentages are based on components (a), (b) and (c).) A fabric suitable for providing arc and thermal protection, comprising. The method of claim 11, (a) 45 to 60% by weight of modacryl fiber, (b) 15 to 35 weight percent of cotton fibers and (c) 5 to 30% by weight of aramid fibers Fabric comprising a. The fabric of claim 11 wherein the char length according to ASTM D-6413-99 is less than 6 inches. 12. The fabric of claim 11 wherein the char length according to ASTM D-6413-99 is less than 4.5 inches. 12. The fabric of claim 11 comprising para-aramid and meta-aramid fibers. 16. The fabric of claim 15 wherein the para-aramid fibers are present in the range of 20 to 40 weight percent and the meta-aramid fibers are in the range of 60 to 80 weight percent, based on the total aramid fibers. The fabric of claim 16 wherein the para-aramid fibers are present in the range of 25 to 35 weight percent and the meta-aramid fibers are present in the range of 65 to 75 weight percent. 12. The fabric of claim 11 further comprising an antistatic component. (a) 40 to 75% by weight of modacryl fiber, (b) 10 to 40% by weight of cotton fibers and (c) 1 to 40% by weight of aramid fibers (The above weight percentages are based on components (a), (b) and (c).) Apparel suitable for providing arc and thermal protection, comprising. The method of claim 19, (a) 45 to 60% by weight of modacryl fiber, (b) 15 to 35 weight percent of cotton fibers and (c) 5 to 30% by weight of aramid fibers Apparel containing a.