DESC:TECHNICAL FIELD OF THE INVENTION
[1] The present invention relates to fabrics, garments for conferring thermal protection against electrical arcs and/or flash fires and method of manufacturing such garments thereof.

BACKGROUD OF THE INVENTION
[2] Flame-retardant protective wear is typically used when there is a risk of electric arc and/or flash fires. If the workplace contains highly flammable material, additional fire hazards arise from static charge developed on the protective wear.
[3] Fabrics and garments manufactured using low tensile strength flame resistant fibers, break open easily forming a hole upon exposure to intense thermal stress of an electrical arc, rendering the wearer vulnerable to additional injury as a result of the incident energy. Electrical arcs typically involve thousands of volts and thousands of amperes of electrical current, more intense than incident energy such as from a flash fire. Therefore, a protective garment or fabric must resist the transfer of the arc energy through the fabric to the wearer.
[4] Conventional protective garments disclose a blend of flame-retardant cotton or cotton/ Nylon 66 fabrics and a Cotton/Modacrylic flame retardant polymer blended fabric for protection against such electrical arcs. Further, there are fabrics blended with Modacrylic or Polyacrylic Nitrile (PAN) carbon fiber with aramid.
[5] However, it has been observed that these known fabrics / conventional protective garments are ineffective to thermal protection against electrical arcs and/or flash fires. They do not provide complete protection to the wearer. Further, they are of high weight or have limited colour options. They have limited bleach resistance and/or very stringent wash /care instructions.
[6] Therefore, there is a need to overcome one or more of the aforementioned problems.

SUMMARY OF THE INVENTION
[7] Accordingly, an aspect of the present invention discloses a treated protective fabric comprising an intimate blend of natural fibers, flame-retardant vinylon fibers, para-aramid, polyamide fibers and antistatic fibers having a blend ratio of about 60% to 85% natural fibers, about 10% to 20% flame-retardant vinylon fibers, about 5% to 20% para-aramid, about 5% to 10% polyamide fibers and about 0.4% to 3% antistatic fibers, of total fabric weight about 150 to 250 grams per square meter.
[8] According to an embodiment of the present invention, said fabric comprises of intimate blend of polyvinyl alcohol and polyamide fibers in a blend ratio of about 10% to 30%.
[9] In the embodiment, said fabric is made flame-retardant by a proban tetrakis (hydroxymethyl)-phosphonium chloride (THPX) treatment.
[10] In the embodiment, said natural fibers include cotton or cellulosic fibers.
[11] In the embodiment, said fabric complies with the requirements of NFPA 2112, ISO 11612, ISO 11611, EN 1149/5, ASTM F1959/F1959M – 13, and EN 61482-1-1.
[12] In the embodiment, said fabric is woven with twill or satin textile weaves.
[13] In the embodiment, said fabric is made of double yarn woven having yarn count of 2/30s Ne to about 2/60s Ne.
[14] In the embodiment, said fabric has a moisture vapour transmission rate (MVTR) of more than 1400 gm/M2/Day when tested pursuant to ASTM E-96-05.
[15] In the embodiment, said fabric has high abrasion resistance of more than 150000 revolutions when tested pursuant to ISO 12947/2 or ASTM D4966.
[16] In the embodiment, said fabric has an arc thermal protective value (ATPV) of more than 8 Cal/cm2 at 180gsm weight when tested pursuant to ASTM F1959/F1959M – 13.
[17] According to another aspect, the present invention discloses method for manufacturing garment from the fabric comprising the steps of:
a) spinning an intimate blend of natural fibers, flame-retardant vinylon fibers, para-aramid fibers, polyamide fibers and antistatic fibers through a ring spinning system to form yarns, said natural fibers include cotton or cellulosic fibers;
b) weaving with twill or satin textile weaves to form fabric;
c) wet processing said fabric, wherein said fabric is padded with a vat dye and an auxiliary pad dry - pad steam process and dried about 1400C and then said fabric is made flame-retardant by proban tetrakis (hydroxymethyl)-phosphonium chloride (THPX) treatment; and
d) garmenting with flame retardant trims to form a protective garment.

DETAILED DESCRIPTION OF THE INVENTION
[18] In general, the present invention discloses a treated protective fabric comprising an intimate blend of natural fibers, flame-retardant vinylon fibers, para-aramid, polyamide fibers and antistatic fibers having a blend ratio of about 60% to 85% natural fibers, about 10% to 20% flame-retardant vinylon fibers, about 5% to 20% para-aramid, about 5% to 10% polyamide fibers and about 0.4% to 3% antistatic fibers, of total fabric weight about 150 to 250 grams per square meter. The fabric is made flame-retardant by a proban tetrakis (hydroxymethyl)-phosphonium chloride (THPX) treatment. The fabric complies with the requirements of NFPA 2112, ISO 11612, ISO 11611, EN 1149/5, ASTM F1959/F1959M – 13, and EN 61482-1-1. The intimate blend is spun through a ring spinning system to form yarns and twill or satin textile woven to form fabric. The fabric is padded with a vat dye and an auxiliary pad dry - pad steam process and dried about 1400 C and garmented with flame retardant trims to form a protective garment.
[19] According to an embodiment, the present invention discloses a treated protective fabric consisting of an intimate blend of natural fibers, flame-retardant vinylon fibers, para-aramid, polyamide fibers and antistatic fibers having a blend ratio of about 60% to 85% cotton / cellulosic fibers, about 10% to 20% flame-retardant vinylon fibers, about 5% to 20% para-aramid, about 5% to 10% polyamide fibers and about 0.4% to 3% antistatic fiber, of total fabric weight about 150 to 250 grams per square meter.
[20] According to the embodiment, said fabric consists of intimate blend of polyvinyl alcohol and polyamide fibers in a blend ratio of about 10% to 30%.
[21] According to the embodiment, said natural fibers include cotton or cellulosic fibers.
[22] According to the embodiment, the protective garment consists of a blend of thermoplastic fiber i.e. a blend of Poly Vinyl Alcohol and Polyamide fibers in an amount of about 10% to 30% by weight of a total protective fabric weight that confers higher thermal stability.
[23] According to the embodiment, the protective garment is treated with a proban tetrakis (hydroxymethyl)-phosphonium chloride (THPX) treatment.
[24] In the embodiment, the protective fabric is air permeable and moisture vapour permeable. The protective fabric may reduce perspiration and provide greater comfort to a user for longer periods of time.
[25] In the embodiment, the protective fabric has a MVTR (Moisture Vapour Transmission Rate) of more than 1400 gm/M2/Day when tested pursuant to ASTM E-96-05.
[26] In the embodiment, the protective fabric has high abrasion resistance of more than 150000 revolutions when tested pursuant to ISO 12947/2 or ASTM
D4966.
[27] According to the present invention, the garment may be dimensionally stable (i.e., display reduced stretching or shrinking), and optionally further comprise other functional durable finishes such as an anti-microbial, water and oil repellent, stain release finishes and the like, without affecting protective performance.
[28] According to the present invention, the protective garment confers thermal protection against arc / flash fire hazard and has aesthetic properties like colour, breathability and/or durability and are suitable for are light weight protective wear.
[29] According to the embodiment, the protective garment is woven with textile weaves such twill or satin textile weaves or their derivative.
[30] According to the embodiment, the yarn count of the fabric may be varied from about 2/30s Ne to about 2/60s Ne (double yarn) for imparting good lustre and strength while having the same resultant count of single yarn i.e. the twist multiplier of 4.5 remains constant for any count of yarn (single yarn).
[31] According to the embodiment, the protective garment has an arc thermal protective value (ATPV) of more than 8 Cal/cm2 (HRC 2) at 180 gsm weight when tested pursuant to ASTM F1959/F1959M – 13.
[32] According to another aspect, the present invention discloses a method of manufacturing an inherently protective garment comprises the steps of (A) spinning a blend of natural fibers in an amount of about 60% to 85% by weight of said total protective fabric weight, flame-retardant vinylon fibers in an amount of about 10% to 20% by weight of a total protective fabric weight, Para Aramid fibers in an amount of about 5% to 20% by weight of said total protective fabric weight, Polyamide fibers in an amount of about 5% to 10% by weight of said total protective fabric weight and antistatic fiber in an amount of about 0.4% to 3% by weight of said total protective fabric weight, through a ring spinning system.
[33] In the embodiment, natural fibers include cotton or cellulosic fibers.
[34] In the embodiment, the protective garment consists of a blend of thermoplastic fiber i.e. a blend of Poly Vinyl Alcohol and Polyamide fibers in an amount of about 10% to 30% by weight of a total protective fabric weight that confers higher thermal stability.
[35] According to the embodiment, the step (A) further includes operations of (a) blow room, wherein opening and blending of the different fibers in specific proportion is conducted, then the blended fibers are sent to next machine by a chute feed system. Spinning oil is added to reduce antistatic charge and increase fiber cohesive force;
(b) carding, wherein a carding machine cleans all the impurities, naps etc. and provides an output sliver;
(c) draw framing, wherein the fibers are made more parallel by drafting and removing hooks;
(d) speed framing, wherein the fibers are roved and fed as input material to a ring framing operation;
(e) ring framing, wherein to make single yarn, a separate specialized ring frame line, having 30 mm diameter of drafting roller for aramid blended yarn and for fiber having staple length 51 mm is used;
(f) winding for making a bigger package and remove objectionable faults like thick and thin segments from the ring yarn;
(g) steaming for removing snarling by eliminating any tendency for undesirable torqueing. The yarn is made to relax till it is stable, the steam treatment to yarn is given at 900 C in an autoclave;
(h) parallel winding, wherein two yarns are wound as required for double yarn; and
(i) twisting, wherein a required twist in the yarn is provided. Double yarn gives good lustre and strength while having the same resultant count of single yarn.
[36] According to step (B), the method discloses, weaving said fabric with textile weaves such twill or satin textile weaves or their derivative of 150 gsm to 250 gsm weight.
[37] In the embodiment, the step (B) further includes the step of:
(a) warping, wherein a warp sheet is made for loom;
(b) sizing, wherein starch with softener and thickener is added for enhancing weavability properties, especially lubrication, binding and antistatic properties; and
(c) weaving, wherein a twill base rip-stop weave fabric is weaved with an air jet loom having 12 shafts drafting at 1000 rpm loom speed.
[38] According to step (C), the method discloses wet processing of said fabric, said wet processing further includes the step of:
(a) singeing, wherein a singeing machine through a gas burner burns out any protruding fibers for improving the resistance to pilling and imparting luster to the fabric;
(b) desizing, wherein oxidative desizing of said fabric when treated for a predetermined period of at least 8 hours that removes any added impurities like size, spinning oil etc.;
(c) washing, wherein the fabric is washed with hot water to remove impurities;
(d) continuous scouring and bleaching, wherein treatment with hydrogen peroxide, a Caustic, a H2O2 stabilizer, a sequestering agent and steam accelerating for a predetermined period of at least 10 minutes, followed by washing removes all the natural impurities and natural color;
(e) mercerization, wherein treatment with at least 310 gpl caustic in tight mode for at least 56 sec provides a cotton rod like structure from twisted ribbon like structure imparting luster and dimensional stability.
(f) dyeing, wherein said fabric is padded with a vat dye and an auxiliary (PDPS - Pad dry - pad steam process) and dried at 1400 C.
[39] According to the embodiment, further, in step (g) said fabric may be developed on a continuous dyeing range (CDR) machine by treating with a reducing agent and steaming for a prescribed time of 1 minute. Then said fabric may be oxidized with H2O2, washed and dried on a vertical drying range (VDR) at 800 C.
[40] In the embodiment, further, step (h) includes a proban tetrakis (hydroxymethyl)-phosphonium chloride (THPX) treatment, wherein a first coating, fabric is treated with THPX chemical by padding and dry process resulting to a moisture content of at least 8%. In the second coating, fabric is given an ammonia treatment followed by oxidative washing.
[41] In the embodiment, further, step (i) includes sanforizing, wherein said fabric may be shrunken length and width wise to provide a permanent dimension to said fabric.
[42] In the embodiment, further, step (j) includes garmenting, wherein the fabric, is garmented with flame retardant trims.
[43] According to the present invention, the fabrics and/or garments confer thermal protection against flash fires, and also against electrical arcs. Further, the garments / fabrics comprise with antistatic fibers that reduce the risk of static charge and consequent fire hazards associated with static energy. The fabrics and garments described herein resist the transfer of energy when exposed to the intense thermal stress of an electrical arc by absorbing a portion of the incident energy and through charring which allows for a reduction in transmitted energy.
[44] According to the present invention, the fabrics are dyed with vat dyes thereby allowing for fastness of colors. As the colors are fast, there are no limitations on wash care like oxidative bleaching or drying. Further, the vat dyeing process overcomes limits on colors of fabrics when compared to other processes for making fabrics.
[45] According to the present invention. THPX treatment has industrial importance in the production of crease-resistant and flame-retardant finishes on cotton textiles and other cellulosic fabrics. A flame-retardant finish can be prepared from THPX by the Proban Process, in which THPC is treated with urea. The urea condenses with the hydroxymethyl groups on THPX. The phosphonium structure is converted to phosphine oxide as the result of this reaction.
[P(CH2OH)4]X + NH2CONH2 ? (HOCH2)2POCH2NHCONH2 + HX + HCHO + H2 + H2O
The reaction proceeds rapidly, forming insoluble high molecular weight polymers. The resulting product is applied to the fabrics in a "pad-dry process." This treated material is then treated with ammonia and ammonia hydroxide to produce fibers that are flame-retardant. THPX can condense with many other types of monomers in addition to urea. These monomers include amines, phenols, and polybasic acids and anhydrides.
[46] The following examples show various results obtained when tested to the following standards:
Example 1:
[47] A fabric made of double yarn having yarn count of about 2/40s Ne is woven with an intimate blend of natural fibers, flame-retardant vinylon fibers, para-aramid, polyamide fibers and antistatic fibers having a blend ration of about 69% cotton fibers, about 20% flame-retardant vinylon fibers, about 5% kelvar fibers, about 5 % nylon 66 (polyamide 66) fibers, about 1% antistatic fibers of total fabric weight about 220 grams per square meter. The weave type of the fabric is 2/2 rht. The following results have been obtained when the fabric of above-mentioned composition is tested pursuant to international standards:
The fabric has a tensile strength of about 1000N in warp and 500N in weft, when tested pursuant to ISO 13934-1;
The fabric has a tear strength of about 30N in warp and about 25 N in weft, when tested pursuant to ISO 13937-2;
The fabric has high abrasion resistance of more than 150000 revolutions when tested pursuant to ISO 12947/2 without any thread break;
The fabric has flame resistance as per ASTMD6413 surface ignition with damage length of about 70 mm. The fabric has no after flame, and no afterglow.
The fabric has an arc thermal protective value (ATPV) of about 8.4 Cal/cm2 when tested pursuant to ASTM F1959/F1959M.
Example 2:
[48] A fabric made of double yarn having yarn count of about 2/30s Ne is woven with an intimate blend of natural fibers, flame-retardant vinylon fibers, para-aramid, polyamide fibers and antistatic fibers having a blend ration of about 69% cotton fibers, about 20% flame-retardant vinylon fibers, about 5% kelvar fibers, about 5 % nylon 66 (polyamide 66) fibers, about 1% antistatic fibers of total fabric weight about 280 grams per square meter. The weave type of the fabric is 3/1 rht. The following results have been obtained when the fabric of above-mentioned composition is tested pursuant to international standards:
[49] The fabric has a tensile strength of about 1250N in warp and 750N in weft, when tested pursuant to ISO 13934-1;
The fabric has a tear strength of about 60N in warp and about 60N in weft, when tested pursuant to ISO 13937-2;
The fabric has high abrasion resistance of more than 250000 revolutions when tested pursuant to ISO 12947/2 without any thread break;
The fabric has flame resistance as per ASTMD6413 surface ignition with damage length of about 40 mm. The fabric has no after flame, and no afterglow.
The fabric has an arc thermal protective value (ATPV) of about 15 Cal/cm2 when tested pursuant to ASTM F1959/F1959M.
Example 3:
[50] According to the present invention, an “Arc Thermal Protective Value” (ATPV) refers to the maximum incident energy (in calories per centimeter squared) that protective fabric can be exposed to and prevent onset of a second-degree burn. Ratings are based upon the total weight of the fabric. A Hazard Risk Category (HRC) level is determined by the minimum number of calories per square centimeter (ATPV or Cal/cm2). Any treated garment must pass through with a 50% probability of a 2nd or 3rd degree burn occurring, which is how the protective level of the treated clothing is determined. The higher the ATPV, the higher the HRC level attained, the greater the protection that is needed. Typical HRCs are given below.
HRC 1: 4 Cal/cm2 = ATPV < 8 Cal/cm2
HRC 2: 8 Cal/cm2 = ATPV < 25 Cal/cm2
HRC 3: 25 Cal/cm2 = ATPV < 40 Cal/cm2
HRC 4: 40 Cal/cm2 = ATPV
According to the embodiment, the protective garment has an arc thermal protective value (ATPV) of more than 8 Cal/cm2 (HRC 2) at 180gsm weight when tested pursuant to ASTM F1959/F1959M.
[51] According to the present invention ISO 12947-2, ASTM D4966: refers to code, wherein the fabric being tested is pulled taut and loaded onto the lower plates of the Martindale machine. Small discs of worsted wool or wire mesh (the abradant) are continually rubbed against the test specimens in a Lissajous oscillating circle with a lode of 12 kpa or more / less as per fabric gsm. The fabric is continually inspected for wear and tear, and the test ends when two yarns break.
[52] According to the present invention, “Tensile strength” refers to the maximum amount of stress that can be applied to a material before rupture or failure. The “tear strength” is the amount of force required to tear a fabric. In general, the tensile strength of a fabric relates to how easily the fabric will tear or rip. The tensile strength may also relate to the ability of the fabric to avoid becoming permanently stretched or deformed. The tensile and tear strengths of a fabric should be high enough so as to prevent ripping, tearing, or permanent deformation of the garment in a manner that would significantly compromise the intended level of protection of the garment.
[53] The National Fire Protection Association (NFPA) is a United States trade association, albeit with some international members, that creates and maintains private, copyrighted standards and codes for usage and adoption by local governments. This includes publications from model building codes to the many on equipment utilized by firefighters while engaging in hazardous material (hazmat) response, rescue response, and some firefighting. The NFPA 2112 standard provides minimum requirements for the design, construction, evaluation, and certification of flame-resistant garments for use by industrial personnel, with the intent of not contributing to the burn injury of the wearer, providing a degree of protection to the wearer, and reducing the severity of burn injuries resulting from short-duration thermal exposures or accidental exposure to flash fires. The International Organization for Standardization (ISO) is an international standard-setting body composed of representatives from various national standards organizations. ISO 15025: Protective clothing -- Protection against heat and flame -- Method of test for limited flame spread. EN 1149/5 Electrostatic properties. Material performance and design requirements: This standard specifies requirements for materials and design of protective clothing with electrostatic dissipation, used as part of a complete set grounded to avoid incendiary discharges. These requirements may not be sufficient in flammable atmosphere rich in oxygen. This European Standard is not applicable for protection against voltage. Other standards are ASTM F1959/F1959M – 13: Standard Test Method for Determining the Arc Rating of Materials for Clothing. EN 61482-1-1: Determination of the arc rating (ATPV) of flame-resistant materials for clothing.
[54] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
[55] The present invention has been described in the context of a protective fabric which confers thermal protection against flash fires, and electrical arcs and also has aesthetic properties like colour, breathability and/or durability. The yarns, fabrics and garments disclosed by the embodiments of the present invention resist the transfer of energy when exposed to the intense thermal stress of an electrical arc by absorbing a portion of the incident energy and through charring which allows for a reduction in transmitted energy. However, the fabric can be used in any type of protective garments for any fire-retardant applications such as home interiors, Electric Arc suits and fire blankets.
[56] In the foregoing detailed description of aspects embodiments of the invention, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the detailed description of aspects, embodiments of the invention, with each claim standing on its own as a separate embodiment.
[57] It is understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined in the appended claims. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” is used as the plain-English equivalent of the respective term “comprising” respectively.

,CLAIMS:
1. A treated protective fabric comprising:
an intimate blend of natural fibers, flame-retardant vinylon fibers, para-aramid, polyamide fibers and antistatic fibers having a blend ratio of about 60% to 85% natural fibers, about 10% to 20% flame-retardant vinylon fibers, about 5% to 20% para-aramid fibers, about 5% to 10% polyamide fibers and about 0.4% to 3% antistatic fibers, of total fabric weight about 150 to 250 grams per square meter.

2. The fabric as claimed in claim 1, wherein said fabric comprises intimate blend of polyvinyl alcohol and polyamide fibers in a blend ratio of about 10% to 30%.

3. The fabric as claimed in claim 1 or 2, wherein said fabric is made flame-retardant by a proban tetrakis (hydroxymethyl)-phosphonium chloride (THPX) treatment.

4. The fabric as claimed in claims 1-3, wherein said natural fibers include cotton or cellulosic fibers.

5. The fabric as claimed in claims 1-4, wherein said fabric complies with the requirements of NFPA 2112, ISO 11612, ISO 11611, EN 1149/5, ASTM F1959/F1959M – 13, and EN 61482-1-1.

6. The fabric as claimed in claims 1-5, wherein said fabric is woven with twill or satin textile weaves.

7. The fabric as claimed in claims 1-6, wherein said fabric is made of double yarn woven having yarn count of about 2/30s Ne to about 2/60s Ne.

8. The fabric as claimed in claims 1-7, wherein said fabric has a moisture vapour transmission rate (MVTR) of more than 1400 gm/M2/Day when tested pursuant to ASTM E-96-05.

9. The fabric as claimed in claims 1-8, wherein said fabric has high abrasion resistance of more than 150000 revolutions when tested pursuant to ISO 12947/2 or ASTM D4966.

10. The fabric as claimed in claims 1-9, wherein said fabric has an arc thermal protective value (ATPV) of more than 8 Cal/cm2 at 180gsm weight when tested pursuant to ASTM F1959/F1959M.

11. A method for manufacturing garment from the fabric as claimed in any of the preceding claims 1-10 comprising the steps of:
a) spinning an intimate blend of natural fibers, flame-retardant vinylon fibers, para-aramid, polyamide fibers and antistatic fibers through a ring spinning system to form yarns, said natural fibers include cotton or cellulosic fibers;
b) weaving with twill or satin textile weaves to form fabric;
c) wet processing said fabric, wherein said fabric is padded with a vat dye and an auxiliary pad dry - pad steam process and dried about 1400C and then said fabric is made flame-retardant by proban tetrakis (hydroxymethyl)-phosphonium chloride (THPX) treatment; and
d) garmenting with flame retardant trims to form a protective garment.