MXPA06010452A

MXPA06010452A - Modacrylic/cotton/aramid fiber blends for arc and flame protection

Info

Publication number: MXPA06010452A
Application number: MXPA/A/2006/010452A
Authority: MX
Inventors: Zhu Reiyao
Original assignee: Ei Dupont De Nemours And Company; Zhu Reiyao
Priority date: 2004-03-18
Filing date: 2006-09-13
Publication date: 2007-04-10

Abstract

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

Description

MIXTURES OF MODACRYLIC FIBER / COTTON / ARAMIDA FOR PROTECTION AGAINST ARC FLASH AND FLAMES FIELD OF THE INVENTION This invention relates to a mixed yarn useful for the production of fabrics which possess protective properties against electric arc and flames. This invention also relates to garments produced with such fabrics.

BACKGROUND OF THE INVENTION Individuals who work near energized electrical equipment and emergency personnel who respond to incidents near electrical equipment are at risk of electric arc hazards and flames which may result from an arcing event. Electric arcs are extremely violent events typically involve thousands of volts and thousands of amps of electricity. Electric arcs are formed in the air when the potential difference (ie, voltage) between two electrodes causes the atoms in the air to ionize and become able to conduct electricity. Flame-resistant garments and electric arc protectors are typically not user-friendly due to the poor transportation of Ref. 174807 moisture vapor from the protective fibers incorporated inside. Individuals who wear protective clothing typically experience both tactile discomfort and thermal stress as a result of the protective fibers incorporated into their protective garments. U.S. Patent 5,208,105 to Ichibori et al. discloses a mixture of flame retardant composite fibers comprising a halogen-containing fiber having a large amount of an antimony compound and at least one fiber selected from the list consisting of natural fibers and chemical fibers. The fiber mixture is woven into a cloth which is then tested for the Limited Oxygen Index as a measure of its flame resistance. U.S. Patent 5,223,334 to Green discloses a fabric that offers the protection of radiant energy due to electric arcs. Green does not describe the use of modacrylic fibers within the mixed yarn. In addition, -Green does not disclose a protective fabric formed of yarns comprising less than 50 percent cotton. What is needed is a thread, cloth and garment to provide a high level of protection when exposed to an electric arc and also flame resistance to protect the user from side effects.

BRIEF DESCRIPTION OF THE INVENTION This invention relates to a yarn for use in protective fabrics and garments against electric arc and flame comprising: (a) 40 to 75 weight percent modacrylic fiber, (b) 10 to 40 percent by weight of cotton fiber and (c) 1 to 25 weight percent of aramid fiber, the percentages based on components (a), < b), and (c). j The yarn is useful for incorporation into a thermally and electrically arc resistant fabric and garment suitable for protecting workers against electric arc. In addition, the fabric and garment can provide resistance to breakage, flame and abrasion.

DETAILED DESCRIPTION OF THE INVENTION This invention relates to the proportion of a yarn, fabric and garment to provide both electric arc protection and flame resistance. Fabrics and garments comprising flame resistant fabrics of low tensile strength when exposed to the intense thermal stress of an electric arc can be broken exposing the user to further injury as a result of the incident energy. Arcs typically involve thousands of volts and thousands of amperes of electrical current. The electric arc is much more intense than the incident energy such as instant fire. To offer protection to a user a garment or cloth must resist the transfer of energy through the user. It is believed that this occurs both by the fabric that absorbs a portion of the incident energy and by the fabric that resists breaking. During breakage a hole is formed in the fabric by directly exposing the surface or user to the incident energy. The threads, fabrics and garments of this invention when exposed to the intense thermal stress of an electric arc resist the transfer of energy. It is believed that this invention reduces energy transfer by absorbing a portion of the incident energy and through carbonization allows a reduction in transmitted energy. The yarns of this invention comprise a blend of modacrylic fiber, cotton fiber, and aramid fiber. Typically, the yarns of this invention comprise 40 to 75 weight percent modracrylic fiber, 10 to 40 weight percent cotton fiber, and 10 to 40 weight percent aramid fiber. Preferably, the threads of this invention comprise 45 to 65 weight percent modacrylic fiber, 15 to 35 weight percent cotton fiber, and 5 to 30 weight percent aramid. The above percentages are on the basis of the three named components. By "yarn" is meant an association of spun or twisted fibers together to form a continuous filament, which may be used in weaving, knitting, braiding, or folding, or otherwise made into a fabric or textile material. By modacrylic fiber is meant acrylic synthetic fiber made of a polymer comprising mainly acrylonitrile. Preferably, the polymer is a copolymer comprising 30 to 70 weight percent of an acrylonitrile and 70 to 30 weight percent of a vinyl monomer containing halogen. The halogen-containing vinyl monomer is at least one monomer selected, for example, from vinyl chloride, vinylidene chloride, vinyl bromide, vinylidene bromide, etc. Examples of copolymerizable vinyl monomers are acrylic acid, methacrylic acid, salts or esters of such acids, acrylamide, methylacrylamide, vinyl acetate, etc. The preferred modacrylic fibers of this invention are copolymers of acrylonitrile combined with vinylidene chloride, the copolymer further having an antimony oxide or antimony oxides for improved fire retardancy. Such useful modacrylic fibers include, but are not limited to, the fibers described in U.S. Patent No. 3,193,602 having 2 percent by weight of antimony trioxide, the fibers described in U.S. Patent No. 3,748,302 made with various antimony oxides which are present in an amount of at least 2 weight percent and preferably no greater than 8 weight percent, and the fibers described in U.S. Patent Nos. 5,208,105 and 5,506,042 having 8 to 40 weight percent of an antimony compound. Within the yarns of this invention, the modacrylic fiber provides a flame-resistant carbonization forming fiber with an IOL typically of at least 28 depending on the level of doping with the antimony derivatives. Modacrylic fiber is also resistant to the extension of fiber damage due to exposure to flames. Modacrylic fiber while being highly flame resistant does not by itself provide adequate tensile strength to a yarn or cloth made of the yarn to offer the desired level of tear strength when exposed to an electric arc. As used herein, "aramid" is understood to mean a polyamide wherein at least 85% of the amide bonds (-CONH-) are directly attached to two aromatic rings. The additives can be used with aramid and, in fact, it has been found that up to as much as 10 percent by weight of other polymeric material can be mixed with aramid or that copolymers having as much as 10 percent can be used of another substituted diamine for the diamine of the aramid or as much as 10 percent of another substituted diacid chloride for the diacid chloride of the aramid. Suitable aramid fibers are described in Man-Made Fibers-Science and Technology, Volume 2, Section entitled Fiber-Forming Aromatic Polya ides, page 297, W. Black et al., Interscience Publishers, 1968. Aramid fibers are also described in U.S. Patent Nos. 4,172,938; 3,869,429; 3,819,587; 3,673,143; 3,354,127; and 3,094,511. The m-aramides are those aramides where the amide bonds are in the meta position relative to each other, and the p-aramides are those aramides where the amide bonds are in the para position relative to each other. In the practice of this invention, the most frequently used aramides are poly (paraphenylene terephthalamide) and poly (metaphenylene isophthalamide). It is within the scope of this invention that a single type of aramid fiber can be employed. Illustratively, either a meta-aramid fiber or para-aramid can be used. However, in a preferred mode both the para-aramid and meta-aramid fibers are used. An illustrative percentage is 20 to 40 weight percent para-aramid fibers and 60 to 80 weight percent meta-aramid fibers. The above percentages are on a base of aramid only. A preferred range of these two aramides is 25 to 35 weight percent para-aramid and 65 to 75 weight percent meta-aramid. Within the yarns of this invention the cotton fibers provide a flame resistant fiber that provides moisture transport within the yarn. Garments comprising cotton fibers improve user comfort by purging user moisture. By allowing the sweating to purge, thermal stress is reduced to a user who is exercising on his own. Additionally, an antistatic component such as steel fiber, carbon fiber, or a carbon coating to an existing fiber may be added to the yarn, fabric, or garment of this invention. The conductivity of the carbon or a metal such as steel when incorporated into a yarn, cloth or garment of this invention provides electrical conduit to assist in the dissipation of static electricity buildup. Static electric shocks can be dangerous for workers who work with sensitive electrical equipment or nearby flammable vapors. The yarns of this invention can be produced by any of the yarn spinning techniques commonly known in the art such as but not limited to ring spinning, core spinning, and air jet spinning or superior air spinning techniques such as like Murata air jet spinning where air is used to twist the fibers cut into a thread. Typically the single threads produced by any of the common techniques are then folded together to form a twisted cape thread comprising at least two unique threads prior to being converted into a fabric. To provide protection from the intense thermal stresses caused by electric arcs it is desirable that an electric arc protective cloth and garments formed of this fabric possess characteristics such as an IOL above the concentration of oxygen in air for flame resistance. , a short carbonization length indicative of slow propagation of damage to the fabric, and good breaking strength to prevent the incident energy from directly hitting the surfaces below the protective layer. Thermally protective garments such as firemen's luggage typically provide protection from the heat of convection generated by an outdoor flame. Such garments-protective when exposed to the intense energy generated by an electric arc can be broken (ie, a form of opening in the fabric) resulting in the penetration of energy to the garment and causing severe injury to the garment. user. The fabrics of this invention provide both protection against the convective heat of an outdoor flame and offer increased resistance to breakage and energy transfer when exposed to an electric arc. The thickness of the fabric and total weight of a protective garment such as a lining Typically used firefighters' luggage can cause thermal stress to a user trapping body heat and sweating then to the skin. The fabrics of this invention comprise a moisture transport fiber such as cotton within yarns of the fabric to provide a means for the moisture due to sweating to be purged from the wearer thereby improving comfort and reducing thermal stress. The basis weight is a measure of the weight of a fabric per unit area. Typical units include ounces per square yard and grams per square centimeter. The base weights reported in this specification are reported in ounces per square yard (OPYC). When the amount of fabric per unit area increases the amount of material between a potential hazard and the subject to be protected increases. An increase in the base weight of a material suggests that a corresponding increase in protective performance will be observed. An increase in the basis weight of the fabrics of this invention results in increased breaking strength, increased thermal protection factor, and increased arc protection. The basis weights of the fabrics of this invention are typically greater than about 8.0 opyc (271.2 gpmc), preferably greater than about 8.7 opyc (294.9 gpmc), and most preferably greater than about 9.5 opyc (322.0 gpmc). It is believed that the fabrics of this invention with base weights greater than about 12 opyc (406.8 gpmc) could show increased stiffness and could thereby reduce the comfort of a garment produced from such a fabric. The carbonization length is a measure of the flame resistance of a textile. A carbonization is defined as a carbonaceous residue formed as the result of pyrolysis or incomplete combustion. The carbonization length of a fabric under the ASTM 6413-99 test conditions as reported in this specification is defined as the distance from the edge of the fabric, which is directly exposed to the flames to the furthest point of the damage of the fabric. visible fabric after a specified tear force has been applied. Preferably the fabrics of this invention have a carbonization length of less than 6 inches (15.24 cm) and preferably less than 4.5 inches (11.43 cm).

The fabrics of this invention can be used as a single layer or as part of a multi-layer protective garment. The yarns of this invention may be present in either the warp or fabric fill. Preferably the yarns of this invention are present in both the warp and the filling of the resulting fabric.

TEST METHODS Abrasion Test The abrasion performance of the fabrics of this invention is determined in accordance with ASTM D-3884-01"Standard Guide for Abrasion Resistance of Textile Fabrics (Rotary Platform, Double Head Method)".

Arc Flash Resistance Test The electrical arc resistance of the fabrics of this invention is determined in accordance with ASTM F-1959-99"Standard Test Method for Determining the Are Thermal Performance Valué of Materials for Clothig". Preferably the fabrics of this invention have an electric arc resistance of at least 0.8 calories and more preferably at least 1.2 calories per square centimeter per opyc.

Grip Test The gripping resistance of the fabrics of this invention is determined in accordance with ASTM D-5034-95"Standard Test Method for Breaking Strength and Elongation of .Fabrics (Grab Test)".

Limited Oxygen Index Test The limited oxygen index (IOL) of the fabrics of this invention is determined in accordance with ASTM G-125-00"Standard Test Method for Measuring Liquid and Solid Material Fire Limits in Gaseous Oxidants".

Tear Test The tear strength of the fabrics of this invention is determined in accordance with 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 this invention is determined in accordance with NFPA 2112"Standard on Flame Resistant -Garments for Protection of Industrial Personnel Against Flash Fire".

Vertical Flame Test The carbonization length of the fabrics of this invention is determined in accordance with ASTM D-6413-99"Standard Test Method for Flame Resistance of Textiles (Vertical Method)". The term thermal protector performance (or FPT) refers to a capacity of the fabric to provide continuous and reliable protection to a user's skin under a fabric when the fabric is exposed to a radiant heat or direct flame.

Limited Oxygen Index (IOL) of ASTM G125 / D2863 The minimum oxygen concentration, expressed as a percentage of volume, in a mixture of oxygen and nitrogen that will adjust the flaming combustion of a material initially at room temperature under the conditions of ASTM D2863. To illustrate the present invention, the following examples are provided. All parts and percentages are by weight and degrees in Celsius unless otherwise indicated.

EXAMPLES Modracrylic / Cotton / Aramid Fabric Example 1 A durable and comfortable fabric was prepared having both the warp and filling yarns spun with ring intimate blends of Nomex® type 462, Kevlar® 29, Modacrylic and Cotton. Nomex® type 462 is 93% poly (phenylene isophthalamide) (MPD-I), 5% poly (p-phenylene terephthalamide) (PPD-T) and 2% static dissipative fibers (P-140 from DuPont) , Modacrylic is ACN / polyvinylidene chloride copolymer with 15% antimony (known as Protex®M), and Kevlar® 29 is poly (p-phenylene terephthalamide) (PPD-T). A wick mixed in 10% by weight of Nomex® type 462, 10% by weight of Kevlar® 29, 55% by weight of Modacrylic and 25% by weight of cotton was prepared and processed by the conventional cotton system in a yarn that has a torsional multiplier of 3.7 using a ring loom. The yarn thus made was a single yarn of 24.6 tex (24 cotton count). Two single strands were then bent in the folding machine to make a two-strand thread. Using similar process and same torsion and bending ratio, a 32.8 tex thread (18 cotton count) was made to be used as filler yarn. The threads were then twofold to form a folded yarn. Nomex® / Kevlar® / Modacrylic / cotton yarns were used as the warp and filling in a shuttle loom in a 3 x 1 asadogado construction. The raw asadogado fabric had a construction of 24 ends x 15 passes per cm (60 ends by 39 passes per inch), and base weight of 271.3 g / m? 2 (8 oz / yd? 2). The raw roasting cloth prepared as described above was washed in hot water and dried under low tension. The washed cloth was then jet dyed using basic dye.

Example 2 A durable and comfortable fabric was prepared having both the warp and filling yarns spun with ring of intimate blends of Nomex® type 462, Kevlar® 29, Modacrylic and cotton. Nomex® type 462 is 93% poly (m-phenylene isophthalamide) (MPD-I), 5% poly (p-phenylene terephthalamide) (PPD-T) and 2% static dissipative fibers (DuPont P-140) ), and Modacrylic is ACN / polyvinylidene chloride copolymer with 15% antimony (known as Protex®M), and Kevlar® 29 is poly (p-phenylene terephthalamide) (PPD-T). A wick mixed batch of 10% by weight of Nomex® type 462, 10% by weight of Kevlar® 29, 45% by weight of Modacrylic and 35% by weight of cotton was prepared and processed by the conventional cotton system in a yarn that has a torsional multiplier of 3.7 using a ring loom. The yarn thus made was a single yarn of 24.6 tex (24 cotton count). Two single strands were then bent in the folding machine to make a two-strand thread. Using similar process and twist, a 32.8 tex (18 cotton count) with Nomex® type 462 / Modacrylic blend at a 50/50 ratio was made to be used as filler yarn. The threads were then twofold to form a folded yarn. The Nomex® / Kevlar® / Modacrylic / cotton yarn was used as the warp and Nomex® / Modacrylic yarn as the filling on a shuttle loom in a 3 x 1 asadogado construction. The raw asadogado fabric had a construction of 23 ends x 16 passes per cm (58 ends per 40 strokes per inch), and weight, base of 264.5 g / m 2 (7.8 oz / yd 2). The raw roasting cloth prepared as described above was washed in hot water and dried under low tension. The washed cloth was then jet dyed using basic dye. The following table illustrates the measured properties of examples 1 and 2.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims

CLAIMS Having described the invention as above, the contents of the following claims are claimed as property:

1. Suitable wire to provide protection against electric arc and flame, characterized in that it comprises: (a) 40 to 75 weight percent modacrylic fiber, (b) 10 to 40 weight percent cotton fiber and (c) 1 to 40 percent by weight of aramid fiber, percentages based on components (a), (b) and (c).

2. Thread according to claim 1, characterized in that it comprises: (a) 45 to 60 weight percent modacrylic fiber, (b) 15 to 35 weight percent cotton fiber and (c) 5 to 30 weight percent. 100 percent by weight of aramid fiber.

3. Thread according to claim 1, characterized in that the fiber includes both ole-para and meta-aramid fiber.

4. Thread according to claim 3, characterized in that the para-aramid fiber is present in a range of 20 to 40 weight percent and the meta-aramid fiber is present in a range of 60 to 80 weight percent over the base of the total aramid fiber.

5. Thread according to claim 4, characterized in that the para-aramid fiber is present in a range of 25 to 35 weight percent and the meta-aramid fiber is present in a range of 65 to 75 percent by weight. weight.

6. Thread according to claim 5, characterized in that it additionally contains an anti-static component.

7. Thread according to claim 6, characterized in that the anti-static component is metal or carbon.

8. Thread according to claim 7, characterized in that the anti-static component is carbon.

9. Thread according to claim 1, characterized in that it additionally contains an anti-static component.

10. Thread according to claim 9, characterized in that the anti-static component is carbon.

11. Fabric suitable for providing thermal and arc flash protection, characterized in that it comprises: (a) 40 to 75 weight percent modacrylic fiber, (b) 10 to 40 weight percent cotton fiber and (c) ) 1 to 40 weight percent of aramid fiber, percentages based on components (a), (b) and (c). Fabric according to claim 11, characterized in that it comprises: (a) 45 to 60 weight percent modacrylic fiber, (b) 15 to 35 weight percent cotton fiber and (c) 5 to 30 weight percent. 100 percent by weight of aramid fiber. 13. Fabric according to claim 11, characterized in that the carbonization length according to ASTM D-6413-99 is less than 6 inches (15.24 cm). Fabric according to claim 11, characterized in that the carbonization length according to ASTM D-6413-99 is less than 4.5 inches (10.54 cm). 15. Fabric according to claim 11, characterized in that it includes para- and meta-aramid fibers. 16. Fabric according to claim 15, characterized in that the para-aramid fiber is present in a range of 20 to 40 weight percent and the meta-aramid fiber is present in a range of 60 to 80 percent by weight. weight based on total aramid fiber. 17. Fabric according to claim 16, characterized in that the para-aramid fiber is present in a range of 25 to 35 weight percent and the meta-aramid fiber is present in a range of 65 to 75 percent by weight. weight. 18. Fabric according to claim 11, characterized in that it additionally contains an anti-static component. 19. Garment suitable for providing thermal and arc flash protection, characterized in that it comprises: (a) 40 to 75 weight percent modacrylic fiber, (b) 10 to 40 weight percent cotton fiber and (c) ) 1 to 40 weight percent of aramid fiber, percentages based on components (a), (b) and i). 20. Garment in accordance with claim 16, characterized in that it comprises: (a) 45 to 60 weight percent modacrylic fiber, (b) 15 to 35 weight percent cotton fiber and (c) 5 to 30 weight percent of aramid fiber.