KR20060041294A - Flame retardant fiber blends comprising flame retarded cellulosic fibers and fabrics and garments made therefrom - Google Patents

Abstract

The intimate blend of staple fibers has 10 to 75 parts by weight of one or more aramid staple fibers, 15 to 80 parts by weight of one or more flame retardant cellulosic staple fibers and 5 to 30 parts by weight of one or more polyamide staple fibers. Intimate blends of staple fibers provide yarns and fabrics that are flame retardant, also referred to as fire resistant, and can be used to make fire retardant articles, such as clothing. The flame retardant fabric may have a basis weight of 4 to 15 ounces per square yard.

Flame Retardant Fabric, Staple Fiber, Intimate Blend, Aramid, Flame Retardant Cellulose, Rayon, Polyamide

Description

FLAME RETARDANT FIBER BLENDS COMPRISING FLAME RETARDANT CELLUOSIC FIBERS AND FABRICS AND GARMENTS MADE THEREFROM}

There is a need for flame retardant fabrics, also referred to as fire resistant, that can be used to make garments suitable for people working near flames, high temperatures or electric arc flashes. In addition to exhibiting good thermal performance, effective flame retardant fabrics must be durable, comfortable and low in manufacturing costs. While fabrics made from fibers that are inherently flame retardant have been very useful in protective garments, certain properties of the fibers cause problems. For example, these fibers are difficult to dye, give an uncomfortable fabric texture, and are expensive. To address this problem, fibers that were originally flame retardant were blended with fibers made of other materials. Fiber blending can be used to obtain the desired fabric combining the beneficial properties of each constituent fiber. However, such blending often sacrifices durability and thermal performance.

Certain fiber blends and fabrics made from such blends are known in the art. For example, US Pat. No. 4,920,000 (Green), issued April 24, 1990, discloses a durable, heat resistant fabric comprising a specific blend of cotton, nylon, and heat resistant fibers. US Patent 4,970,111 (Smith, Jr.), registered November 13, 1990, discloses a fire resistant fabric comprising a blend of chlorine containing polymer fibers, polyacrylonitrile fibers, and a refractory polyester binder. U.S. Patent 5,503,916 (Ichibori et al.), Registered April 2, 1996, discloses flame retardant clothing comprising natural or chemical fibers, and polymer fibers containing antimony and halogen compounds. US Patent 6,132,476 (Lunsford et al.), Registered October 17, 2000, discloses dyed fabric blends comprising fibers that are inherently flame retardant, and flame retardant cellulosic fibers containing flame retardant compounds. US Patent 6,254,988 B1 (Zhu et al.), Registered July 3, 2001, discloses a fabric consisting of a specific blend of cotton, nylon, and para-aramid fibers that is comfortable, cut and wear resistant. U.S. Patent Application Publication 2001/0009832 A1 (Shaffer et al.), Published July 26, 2001, includes warp spatter or filament fibers and has a Limiting Oxygen Index of at least 27, Flame retardant fabrics are disclosed that include natural fibers and have dissimilar warp and weft yarns in which the ratio of warp to weft of the fabric is at least 1.0. US Patent 6,547,835 B1 (Lunsford et al.), Registered April 15, 2003, discloses a method of dyeing flame retardant fabrics.

Fabrics made from the fiber blends and yarns discussed above have a large proportion of cotton fibers that are inherently poor in wear resistance or have very low wear resistance as disclosed in US Pat. No. 4,920,000 (Green), registered April 24, 1990. I use it. Flame protective clothing and garments are usually used in harsh environments, so improving the wear resistance of the fabrics used in such garments is important and required. Accordingly, there is a need for flame retardant fiber blends, yarns and fabrics with improved wear resistance.

Summary of the Invention

According to the object of the invention practiced and broadly described herein, the present invention provides 10 to 75 parts by weight of at least one aramid staple fiber, 15 to 80 parts by weight of at least one flame retardant cellulosic staple fiber and 5 to 30 parts by weight of at least one It is an intimate blend of staple fibers comprising polyamide staple fibers of.

In another embodiment, the present invention provides a staple comprising 20 to 40 parts by weight of at least one aramid staple fiber, 50 to 80 parts by weight of at least one flame retardant cellulosic staple fiber and 15 to 20 parts by weight of at least one polyamide staple fiber. It is an intimate blend of fibers.

In another embodiment, the present invention is one of the intimate blends wherein at least one aramid staple fiber is poly (metaphenylene isophthalamide) and at least one flame retardant cellulose staple fiber is flame retardant rayon.

In another embodiment, the present invention provides that the at least one aramid staple fiber is poly (methaphenylene isophthalamide), the at least one flame retardant cellulosic staple fiber comprises silicon dioxide in the form of polysilicate in the cellulose support structure, Silicon dioxide in the form of polysilicate in the support structure is one of the intimate blends present in an amount up to 40% by weight of the intimate blend.

The intimate blends of the present invention can be used in the manufacture of yarns that can be used in the manufacture of fire retardant articles, for example flame retardant fabrics for use in apparel.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from the detailed description, and therefore, it should be understood that the detailed description and specific examples are presented for illustrative purposes only and refer to embodiments of the present invention. do. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and do not limit the claimed invention.

There is a need for fiber blends that can produce flame retardant fabrics, also referred to as fire resistant, that can be used to make clothing and other articles suitable for those working near flames, high temperatures or electric arc flash. Considerable efforts have been made to maintain or enhance their comfort and durability and reduce the overall cost while increasing the effectiveness of the fiber blends and the resulting fabrics. The present invention represents just such progress in the field of flame retardant garments.

Intimate blends of staple fibers of the present invention include aramid fibers, flame retardant cellulosic fibers and polyamide fibers. The proportion of each ingredient is important to achieve the required combination of physical qualities. The term "intimate blend" means that two or more fiber types are blended prior to spinning the yarn. In the present invention, the intimate blend is formed by mixing aramid fibers, flame retarded cellulosic fibers and polyamide fibers in the form of fibers and then spinning into yarns of a single strand. The term "yarn" refers to a collection of fibers that are spun together or twisted together to form a continuous strand that can be used in weaving, knitting, braiding or crimping or can be made of a fabric material or fabric. Such yarns are conventional methods for spinning staple fibers into yarns, such as ring-spinning or high speed air spinning techniques, such as Murata, where air is used to twist staples into yarns. Murata) can be prepared by air jet spinning.

Intimate blends of staple fibers of the present invention include aramid fibers that are inherently flame retardant. "Aramid fiber" means one or more fibers made from one or more aromatic polyamides, wherein at least 85% of the amide (-CONH-) linker is directly attached to the two aromatic rings. Aromatic polyamides are formed by reacting aromatic diacid chlorides with aromatic diamines to produce amide linkages in amide solvents. Aramid fibers can be spun by dry or wet spinning using any number of processes, but are described in US Pat. No. 3,063,966; 3,227,793; 3,287,324; 3,414,645; 3,869,430; 3,869,429; 3,767,756; And 5,667,743 illustrate useful spinning processes for making fibers that can be used in the present invention.

Aramid fibers are usually two distinct types, namely meta-aramid fibers or m-aramid fibers, one of which consists of poly (methaphenylene isophthalamide), also called MPD-I), and para-aramid fibers or p Aramid fibers, one of which consists of poly (paraphenylene terephthalamide), also called PPD-T. Meta-aramid fiber is currently E.I. Wilmington, Delaware, USA. There are several forms available under the tradename NOMEX® from E.I. du Pont de Nemours: NOMEX T-450® is 100% meta-aramid; NOMEX T-455® is a blend of 95% NOMEX® and 5% KEVLAR® (para-aramid); NOMEX IIIA® (also known as NOMEX T-462®) is 93% NOMEX®, 5% KEVLAR® and 2% carbon core nylon. In addition, the meta-aramid fibers are sold under the trade names CONEX® and APYEIL® (Teijin, Ltd., Tokyo, Japan) and Unitika, Eltidy, Osaka, Japan. , Ltd.)). Para-aramid fibers are currently E.I., Wilmington, Delaware, USA under the trade name KEVLAR®. Available from DuPont de Nemewa, and Teijin L.T., Tokyo, Japan under TWARON®. For the purposes herein, TECHNORA® fibers (available from Teijin L. T., Tokyo, Japan) and made from copoly (p-phenylene / 3,4'diphenyl ester terephthalamide) -Considered as aramid fibers.

In one embodiment of the present invention, the at least one aramid staple fiber is poly (methphenylene isophthalamide).

Intimate blends of the staple fibers of the invention also include flame retardant cellulosic fibers. Flame retardant cellulosic staple fibers consist of one or more cellulosic fibers and one or more flame retardant compounds. Cellulosic fibers, such as rayon, acetate, triacetate and lyocell, which are general terms for fibers derived from cellulose, are well known in the art.

Cellulosic fibers are softer and less expensive than fibers that are inherently flame retardant, but do not inherently prevent flame. In order to increase the flame retardancy of these fibers, one or more flame retardants are incorporated into or with the cellulosic fibers. These flame retardants include spinning flame retardants into cellulosic fibers, coating cellulosic fibers with flame retardants, or contacting cellulosic fibers with flame retardants to absorb the flame retardants into the cellulosic fibers, or flame retardants into or with the cellulosic fibers. It may be included by any other process to include. Various flame retardants include, for example, certain phosphorus compounds, such as SANDOLAST 9000® (currently available from Sandoz), certain antimony compounds, and the like. In general, cellulosic fibers containing one or more flame retardants are given the name "FR" for flame retardants. Thus, flame retardant cellulosic fibers such as FR rayon, FR acetate, FR triacetate and FR lyocells can be used in the present invention. Flame retardant cellulosic fibers are also available under various trade names, such as VISIL® (available from Sateri Oy, Finland). VISIL® fibers contain silicon dioxide in the form of polysilicate in the cellulose support structure, wherein the polysilicate comprises aluminum silicate sites. When the intimate blend of the present invention comprises VISIL® fibers, the VIRIL® fibers should be present in an amount up to 40% by weight of the intimate blend. Methods of making fire retardant cellulosic fibers are generally disclosed, for example, in US Pat. No. 5,417,752.

In one embodiment of the invention, the at least one flame retardant cellulosic fiber is flame retardant rayon. Rayon is well known in the art and is a generic term for filaments made from various solutions of modified cellulose by pressing or drawing cellulose solutions. Cellulose bases for rayon production are obtained from wood pulp.

In another embodiment of the present invention, the at least one flame retardant cellulosic staple fiber comprises silicon dioxide in the form of polysilicate in the cellulose support structure, wherein the silicon dioxide in the form of polysilicate in the cellulose support structure comprises up to 40% by weight of the intimate blend. Present in quantities.

Intimate blends of the staple fibers of the present invention also include polyamide fibers. "Polyamide fiber" means one or more fibers made of one or more aliphatic polyamide polymers collectively referred to as nylon. Examples include polyhexamethylene adipamide (nylon 66), polycaprolactam (nylon 6), polybutyrolactam (nylon 4), poly (9-aminononanoic acid) (nylon 9), polyenantholactam (nylon 7), polycapryllactam (nylon 8) and polyhexamethylene sebacamide (nylon 6,10). Nylon fibers are generally spun by extrusion into the gaseous condensation medium through the capillary of the polymer melt. If the nylon is a polyamide fiber in an intimate blend of staple fibers forming a yarn, these yarns preferably form a fabric to enhance protection against soft surface wear in the finished fabric or garments made from these fabrics. When used as a slope. In one embodiment of the invention, when nylon is used in this manner to make the fabric or garment of the invention, the fabric or garment of the invention is subjected to cycles to failure according to the following abrasion resistance test. It is expected to have at least 10% greater wear resistance when compared to similar fabrics without nylon. However, too much nylon in the fabric will cause the fabric to become hard and will lose drape when the fabric is exposed to high temperatures for a while.

In one embodiment of the present invention, the nylon fibers have a linear density of 1 to 3 dtex. In another embodiment, the nylon fiber has a linear density of 1 to 1.5 dtex. In yet another embodiment, the nylon fiber has a line density of about 1.1 dtex.

Intimate blends of staple fibers of the present invention can be used to make yarns and fabrics that are flame retardant. These yarns and fabrics can be used to make fire retardant articles, such as flame retardant garments and clothing, that are particularly useful to firefighters and other workers working in close proximity to flames, high temperature or electric arc flashes. In general, "flame retardant" means that the fabric does not sustain flame in air after contact with the flame for a short time. More precisely, "flame retardant" can be defined by the following vertical flame test. The flame retardant fabric preferably has a char length of less than 6 inches after 12 seconds exposure to flame. The terms "flame retardant", "flame retardant", "fireproof" and "fireproof" are used interchangeably in the industry and reference herein to "flame retardant" compounds, fibers, yarns, fabrics and garments is "flame retardant", " Equally fireproof "or" fireproof ".

Staple fibers for use in spinning yarns are generally those having a certain length and specific line density. For use in the present invention, synthetic fiber staple lengths of 2.5 to 15 cm (1 to 6 inches) and 25 cm (10 inches) can be used, with lengths of 3.8 to 11.4 cm (1.5 to 4.5 inches) being preferred. . Yarns made from such fibers having staple lengths of less than 2.5 cm have been found to require excessively high levels of twist to maintain strength for processing. Yarns made from the aforementioned fibers having a staple length of at least 15 cm are more difficult to manufacture because long staple fibers tend to entangle and cut to produce shorter fibers. Synthetic staple fibers may or may not be crimped if required for any particular purpose. Staple fibers of the present invention are generally made by cutting continuous filaments into certain predetermined lengths. However, staple fibers can be made by other means, for example by stretch-breaking, and yarns can be made from the fibers and from various different staple fiber lengths.

In one embodiment of the present invention, the yarns of the present invention can be used to make flame retardant fabrics, which are fabrics that can be made by weaving, knitting or otherwise blending the yarns of the present invention. Flame retardant fabrics having warp yarns comprising the yarns of the present invention, weft yarns comprising the yarns of the present invention, or warp yarns and wefts comprising the yarns of the present invention can be fabricated. If the fabric uses the yarns of the present invention in only one direction (ie only weft or ramp), other suitable yarns may be used in other directions depending on the desired fabric properties. For best wear resistance, the yarns of the present invention are used in the warp direction, since the warp usually forms most of the direct contact surface of the fabric. This translates to better wear performance of the outer surface of the fabric in garment form.

In one embodiment of the present invention, the flame retardant fabric has a basis weight of 4 to 15 ounces per square yard. In another embodiment of the present invention, the flame retardant fabric has a basis weight of 5.5 to 11 ounces per square yard. These fabrics can be made in apparel articles such as shirts, pants, overalls, aprons, jackets or any other single or multi-layered form for flame or electric arc protection.

Articles of the invention will be further described below with reference to the examples. However, it should be understood that the concept of the present invention will not be limited by these embodiments.

<Test method>

In the following examples the following test methods were used.

Thermal protection Performance test  ( TPP )

The predicted protective performance of the fabric in heat and flame was measured using the "heat protection performance test" (NFPA 2112). The flames were delivered to the area of the fabric mounted in the horizontal position at a particular heat flow rate (usually 84 kW / m ² ). The test measures the thermal energy transferred through the sample from the heat source using a copper slug calorimeter with no space between the fabric and the heat source. The test endpoint is characterized by the time required to obtain predicted second degree skin burns using a simple model developed by Stol & Chianta ("Transactions New York Academy Science", 1971, 33 p 649). The value assigned to the sample in this test (denoted as the "TPP value") is the total heat energy required to obtain the endpoint, or the direct heat source exposure time x incident heat flow rate for the predicted image. Higher TPP values indicate better insulation performance.

Vertical flame test

The "Vertical Flame Test" (ASTM D6413) is commonly used as a screening test to determine if a fabric burns as a predictor of whether an article of clothing has any flame retardant properties. According to this test, a 3 × 12 inch zone of fabric was mounted vertically and a specific flame was applied to its lower edge for 12 seconds. The response of the fabric to flame exposure was recorded. The length of the burnt or charred fabric was measured. Times after flame (ie, continued burning of the fabric zone after removing the test flame) and after burning (characterized by the burning of the fabric zone after removing the test flame) were also measured. In addition, observations of melting and dripping from the fabric zone were recorded. Passes / failures based on this method are known for industrial worker clothing, firefighter convocation clothing and fire retardant workwear and military clothing. According to industry standards, fabrics can be considered flame retardant or fire resistant if they have a char length less than 6 inches after 12 seconds of exposure to flame.

Abrasion Resistance Test

Wear resistance is achieved by using an H-18 wheel, 500 gms load on a Taper wear meter available from Teledyne Taber, 14120 North Towanda, Bryant Street 455, New York, USA. It was measured using ASTM method D3884. Taber wear resistance was recorded as a cycle for failure.

Tear  Strength test

Tear strength measurements are based on ASTM D 5587. Tear strength of the fabric was measured by a trapezoidal procedure using a record constant tensile (CRE) tensile tester. Tear strength when measured in this test method requires that the tear be initiated before testing. The sample is torn at the center of the trapezoid's shortest base to begin tearing. Labeled trapezoidal non-parallel sides were clamped in parallel jaws of a tensile tester. The spacing of the jaws was continuously increased to force the tear to proceed across the sample. At the same time, the power displayed was recorded. The force to sustain tear was calculated from an automatic chart recorder or microprocessor data acquisition system. Two calculations were provided for the trapezoidal tear strength: the average of the single-peak force and the five highest peak forces. As an example here, a single peak force was used.

grab  (Grab) strength test

Grab strength measurement, which is a measure of the breaking strength and elongation of a fabric or other sheet material, is based on ASTM D5034. A 100 mm (4.0 inch) wide sample was mounted centrally in the clamp of the tensile tester and force was applied until the sample broke. Values for breaking force and elongation of the test sample were obtained from a machine scale or a computer interfaced with the tester.

<Example>

Example  One

Comfortable and durable fabrics from weft yarns comprising an intimate blend of Nomex® Type 462 staple fibers, flame retardant (FR) rayon staple fibers and nylon staple fibers and intimate blends of FR rayon staple fibers and nylon staple fibers Was prepared. Nomex® Type 462 is a 93% by weight poly (m-phenylene isophthalamide) (MPD-I) staple fiber, 5% by weight poly (p-phenylene terephthalamide) (PPD-T) staple fiber and 2 Wt% carbon-core nylon-shell electrostatic dissipating staple fiber (type P-140, available from E.I. DuPont de Nemwa, Wilmington, Delaware). FR rayon is a cellulosic fiber containing a flame retardant compound and nylon is polyhexamethylene adipamide. A picker blend sliver of 40% by weight Nomex® type 462 staple fibers, 45% by weight FR rayon staple fibers and 15% by weight nylon staple fibers was prepared and prepared by conventional cotton systems. The ring spinning machine was used to fabricate a spun yarn with a twist multiplier of 3.5. The yarn thus prepared was 19.7 tex (30 cotton number) single yarn. Two single yarns were then twisted on a plying machine to make a two-ply yarn. Using a similar process and the same twist and yarn density, two-ply yarns were made using a blend of 75 wt% FR rayon staple fibers and 25 wt% nylon fibers.

Nomex® / FR rayon / nylon yarns were used as warp yarns and FR rayon / nylon yarns were used as weft yarns in a 3 × 1 twill structure in a shuttle loom. The raw twill had a structure of 36 ends x 22 picks / cm (92 ends x 57 picks / inch) and a basis weight of 323 g / m ² (9.7 oz / yd ² ). The raw twill fabric prepared as described above was washed in hot water and dried under storage capacity. The washed fabric was then dyed using acid dyes. Finished fabrics were then tested for their thermal and mechanical properties. The results of these tests are shown in Table 1.

Example 1 Test Results Fabric design slope Nomex (trademark) / FR rayon / nylon 40/45/15 weight% Weft FR Rayon / Nylon 75/25 wt% Exam description unit value Basis weight oz / y ² 9.7 Yarn size Count (Bevel x Weft) 30 / 2x30 / 2 TPP cal / cm ² 17.2 Vertical flame charcoal Inch (inclined x weft) 4.7x2.4 Wear cycle 1578 Tear resistance lbf (bevel x weft) 26.6 x 11.0 Grab strength lbf (bevel x weft) 191.0x97.8

Example  2

A comfortable and durable fabric was prepared as in Example 1, but the warp was made from 20% by weight Nomex® Type 462 staple fiber, 55% by weight FR rayon staple fiber and 25% by weight nylon staple fiber. Spun Yarn had a twist coefficient of 3.7. The yarn thus prepared was 24.6 tex (24 facet count) single yarn. Two single yarns were then twisted on a twisting machine to make a two-ply yarn. Using a similar process and the same twist as in Example 1, a 32.8 tex (18 cotton number) comprising a blend of 20% by weight Nomex® type 462 staple fibers and 80% by weight of FR rayon staple fibers Single yarns with a linear density were made. Two of these yarns were then twisted to form a double yarn.

Nomex® / FR Rayon / Nylon Yarn and Nomex® / FR Rayon Yarn were used as the warp and weft yarns in the 3 × 1 twill structure in the weaving machine, respectively. The raw twill had a structure of 26 ends x 17 picks / cm (66 ends x 44 picks / inch) and a basis weight of 323 g / m ² (9.7 oz / yd ² ). The raw twill fabric prepared as described above was washed in hot water and dried under storage capacity. The washed fabric was then dyed using acid dyes. Finished fabrics were then tested for their thermal and mechanical properties. The results of these tests are shown in Table 2.

Example 2 Test Results Fabric design slope Nomex (trademark) / FR rayon / nylon 20/55/25 weight% Weft Nomex® / FR Rayon 20/80 wt% Exam description unit value Basis weight oz / y ² 9.7 Yarn size Count (Bevel x Weft) 24 / 2x18 / 2 TPP cal / cm ² 16.9 Vertical flame charcoal Inch (inclined x weft) 1.0x1.3 Wear cycle 784 Tear resistance lbf (bevel x weft) 18.3 x 14.8 Grab strength lbf (bevel x weft) 121.1 x 124.9

Example  3

Fabrics were prepared as in Example 1, but both warp and weft yarns were fabricated from 50% by weight of Nomex® Type 462 staple fiber, 35% by weight of VISIL® staple fiber and 15% by weight of nylon staple fiber. Was prepared, and the spun yarn had a twist coefficient of 3.7. The yarn thus prepared was 24.6 tex (24 facet count) single yarn. Two of these yarns were then twisted on a twisting machine to make a two-ply yarn. Using the same fiber composition, process and twist coefficient, a single yarn of 32.8 tex (18 cotton number) was prepared. Two of these yarns were then twisted to form a double yarn.

Nomex® / VISIL® / nylon yarn was used as a warp and weft yarn in a 3 × 1 twill structure in a weaving machine. The raw twill had a structure of 23 ends x 16 picks / cm (58 ends x 40 picks / inch) and a basis weight of 247.5 g / m ² (7.3 oz / yd ² ). The raw twill fabric prepared as described above was washed in hot water and dried under storage capacity. The washed fabric was then dyed using acid dyes. Finished fabrics were then tested for their thermal and mechanical properties. The results of these tests are shown in Table 3.

Example 3 Test Results Fabric design slope Nomex (registered trademark) / VISIL (registered trademark) / nylon 50/35/15 weight% Weft Nomex (registered trademark) / VISIL (registered trademark) / nylon 50/35/15 weight% Exam description unit value Basis weight oz / y ² 7.3 Yarn size Count (Bevel x Weft) 24 / 2x18 / 2 TPP cal / cm ² 14.4 Vertical flame charcoal Inch (inclined x weft) 3.7x3.2 Wear cycle 558 Tear resistance lbf (bevel x weft) 30.1 x 34.2 Grab strength lbf (bevel x weft) 157.1 x 168.7

Claims (20)

An intimate blend of staple fibers comprising 10 to 75 parts by weight of one or more aramid staple fibers, 15 to 80 parts by weight of one or more flame retardant cellulosic staple fibers and 5 to 30 parts by weight of one or more polyamide staple fibers. The intimate blend of claim 1 wherein 20 to 40 parts by weight of one or more aramid staple fibers, 50 to 80 parts by weight of one or more flame retardant cellulosic staple fibers and 15 to 20 parts by weight of one or more polyamide staple fibers. The intimate blend of claim 1, wherein the one or more aramid staple fibers are selected from the group consisting of para-aramid fibers, meta-aramid fibers, and mixtures thereof. The intimate blend of claim 2, wherein the at least one aramid staple fiber is selected from the group consisting of para-aramid fibers, meta-aramid fibers, and mixtures thereof. The intimate blend of claim 1, wherein the at least one aramid staple fiber is poly (metaphenylene isophthalamide) and the at least one flame retardant cellulosic staple fiber is flame retardant rayon. 3. The intimate blend of claim 2, wherein the at least one aramid staple fiber is poly (metaphenylene isophthalamide) and the at least one flame retardant cellulosic staple fiber is flame retardant rayon. The method of claim 1, wherein the at least one aramid staple fiber is poly (methphenylene isophthalamide), the at least one flame retardant cellulosic staple fiber comprises silicon dioxide in the form of polysilicate in the cellulose support structure, and the poly in the cellulose support structure. Silicon dioxide in the form of silicic acid is present in an amount of up to 40% by weight of the intimate blend. 3. The method of claim 2, wherein the at least one aramid staple fiber is poly (metaphenylene isophthalamide), the at least one flame retardant cellulosic staple fiber comprises silicon dioxide in the form of polysilicate in the cellulose support structure and the poly in the cellulose support structure. Silicon dioxide in the form of silicic acid is present in an amount of up to 40% by weight of the intimate blend. Yarn comprising the intimate blend of claim 1. A flame retardant fabric comprising the yarn of claim 9. The flame retardant fabric of claim 10, wherein the flame retardant fabric has a basis weight of 4 to 15 ounces per square yard. A flame retardant clothing article comprising the flame retardant fabric of claim 11. The flame retardant fabric of claim 10, wherein the flame retardant fabric has a basis weight of 5.5 to 11 ounces per square yard. A flame retardant clothing article comprising the flame retardant fabric of claim 13. A yarn comprising the intimate blend of claim 5. A flame retardant fabric comprising the yarn of claim 15. The flame retardant fabric of claim 16, wherein the flame retardant fabric has a basis weight of 4 to 15 ounces per square yard. A flame retardant clothing article comprising the flame retardant fabric of claim 17. The flame retardant fabric of claim 16, wherein the flame retardant fabric has a basis weight of 5.5 to 11 ounces per square yard. A flame retardant clothing article comprising the flame retardant fabric of claim 19.