GARMENT AND A COMPOSITE FABRIC FOR USE IN HAZARDOUS ENVIRONMENTS

Abstract

A base layer for use in hazardous environments, such as smoky environments, the base layer (1) comprising a composite fabric (100) comprising a breathable membrane layer (101) having a multiplicity of pores and a breathable fire-retardant fabric layer (102,103) having a multiplicity of openings, the breathable membrane layer laminated on at least one side to the breathable fire-retardant fabric layer with an adhesive (104,105).

Claims

1. Abase layer for use in smoky environments, the base layer comprising a composite fabric comprising a breathable membrane layer having a multiplicity of pores and a breathable fire-retardant fabric layer having a multiplicity of openings, the breathable membrane layer laminated on at least one side to the breathable fire-retardant fabric layer with an adhesive.

2. A base layer as claimed in claim 1, wherein the adhesive is a hotmelt polyurethane and optionally a moisture curing hotmelt polyurethane.

3. A base layer as claimed in claim 1, wherein the breathable membrane is hydrophilic.

4. A base layer as claimed in claim 1, wherein the breathable membrane comprises pores sized to inhibit ingress of particles found in smoke and optionally to allow egress of sweat and moisture.

5. A base layer as claimed in claim 1, wherein the breathable membrane is fire-retardant.

6. A base layer as claimed in claim 1, wherein the breathable membrane is made from a polymer.

7. A base layer as claimed in claim 1, wherein the breathable fire-retardant fabric layer comprises openings which are significantly larger the pores in the breathable membrane.

8. A base layer as claimed in claim 1, wherein the openings are formed between woven yarn and optionally, the yarn is made from polyester filaments which are optionally discontinuous.

9. A base layer as claimed in claim 1, wherein the composite fabric comprises a breathable fabric layer laminated with an adhesive to an opposing side of the breathable membrane layer.

10. A base layer as claimed in claim 1, wherein the breathable membrane layer and the breathable fire-retardant fabric layer each have an elasticity, the elasticity of each being substantially equal.

11. Abase layer as claimed in claim 1, wherein the base layer comprises a base layer top and base layer leggings, wherein the base layer top comprises a portion which covers the torso and sleeves, wherein the sleeves are over-length to cover a portion of the hands and a thumb opening provided and wherein the base layer leggings comprise a waist portion provided with an elastic waist band and elasticated ankle portions. Optionally, the base layer comprises seam stitching with fire-retardant thread.

12. A method of making a composite fabric for use as a garment, the method comprising the steps of unfurling a breathable fire-retardant fabric from a roll of breathable fire-retardant fabric, applying with an engraved roller an amount of adhesive to the fire-retardant fabric, unfurling a breathable membrane from a roll of breathable membrane and passing the fire-retardant fabric with adhesive thereon and breathable membrane through a nip between two rollers to laminate the fire-retardant fabric and breathable membrane to form a composite fabric.

13. A composite fabric comprising a breathable membrane layer having a multiplicity of micropores, the breathable membrane having an inner and outer surfaces, and an inner fabric layer laminated to said inner surface of said breathable membrane and an outer fabric layer laminated to said outer surface of said breathable membrane.

14. A composite fabric as claimed in claim 13, wherein the inner fabric material comprises a woven yarn comprising polyester filaments, optionally, the polyester filaments are discontinuous and may be short polyester fibres and optionally, the yarn or filaments are coated in a fire-retardant coating.

15. A composite fabric as claimed in claim 13, wherein the inner fabric material comprises a woven yarn comprising polyester filaments, optionally, the polyester filaments are discontinuous and may be short polyester fibres and optionally, the yarn or filaments are coated in a fire-retardant coating.

16. A composite fabric as claimed in claim 13, wherein the outer layer comprises a woven yarn comprising polyester filaments, optionally, the polyester filaments are discontinuous and may be short polyester fibres and optionally, the yarn or filaments are coated in a fire-retardant coating.

17. A composite fabric as claimed in claim 13, wherein the breathable membrane layer is a polymer based sheet material with said micropores formed therein.

18. A composite material as claimed in claim 13, wherein said breathable membrane layer is between 10 and 50μ (0.01-0.05 mm) and may be between 20 and 30μ (0.02-0.03 mm) and may be 25μ (0.025 mm).

19. A composite material as claimed in claim 13, wherein said breathable membrane layer has a water vapour transmissibility of between 100 and 1000 (g/m.sup.2/24 hr) and may be of between 400 and 800 (g/m.sup.2/24 hr) and may be of between 500 and 650 (g/m.sup.2/24 hr.

20. A composite material as claimed in claim 13, wherein said breathable membrane layer has a 25% elongation when subjected to between 0.3 and 1 N/cm optionally between 0.5 and 0.8 N/cm and optionally 0.6 to 0.7 N/cm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] For a better understanding of the present invention reference will now be made, by way of example only, to the accompanying drawings, in which:

[0034] FIG. 1 shows a base layer worn by a firefighter, the base layer in accordance with the present invention made from a composite fabric in accordance with the present invention, the base layer comprising base layer leggings and a base layer top;

[0035] FIG. 1A is enlarged perspective view of the leggings shown in FIG. 1;

[0036] FIG. 1B is an enlarged view of the base layer top shown in FIG. 1, as viewed from in front and to the right;

[0037] FIG. 1C is an enlarged view of the base layer top shown in FIG. 1, as viewed from in rear and to the right;

[0038] FIG. 2 is an enlarged scrap schematic end view of the composite fabric of the present invention used in the base layer shown in FIG. 1;

[0039] FIG. 3A is a perspective view of a piece of fabric used in an outer layer of the composite fabric shown in FIG. 2;

[0040] FIG. 3B is an enlarged view of the piece of fabric shown in FIG. 3A, together with a 1 cm scale with divisions of 5 mm, 1 mm and 0.5 mm; FIG. 3C is a perspective view of the composite fabric used in the base layer shown in FIG. 1;

[0041] FIG. 3D is an enlarged view of a piece of fabric used in an inner layer of the shown in FIG. 2, together with a 1 cm scale with divisions of 5 mm, 1 mm and 0.5 mm;

[0042] FIG. 3E is a cross sectional view of the composite fabric of the invention;

[0043] FIG. 4 is a top plan view of a membrane used in the composite fabric;

[0044] FIG. 4A is a view of the composite fabric shown in FIG. 2, in use, the schematic view showing ends of discontinuous fibres;

[0045] FIG. 5A is a schematic view of an apparatus used in a method of making the composite fabric in a first stage of operation;

[0046] FIG. 5B is a schematic view of the apparatus shown in FIG. 5A in a second stage of operation;

[0047] FIG. 6 shows a surface of an engraved roller of the apparatus of FIGS. 5A and 5B;

[0048] FIG. 7A is a side view of an apparatus used in a method of making the composite fabric, with some hidden parts shown; and

[0049] FIG. 7B is a front of the apparatus shown in FIG. 7A.

DETAILED DESCRIPTION

[0050] Referring to FIG. 1 there is shown a base layer in accordance with the present invention, generally identified by reference numeral 1. The base layer 1 comprises a base layer top 2 for covering a torso, arms and a portion of the hands of a firefighter 4 and base layer leggings 3 for covering the bottom part of the torso and legs of the firefighter 4. The base layer 1 covers a major portion of the body of the firefighter 4.

[0051] The base layer leggings 3 has annular elasticated portions 5 and 6 at a lower end of each leg portion 7 and 8. The annular elasticated portions may provide a tight fit around the ankles which may inhibit smoke from rising and passing between the skin and the base layer leggings. It should be noted that above the elasticated portions 5 and 6, there is either a small annular gap between the base layer bottoms and the skin or no gap between the base layer bottoms and the skin. A small annular gap may provide additional insulation and improved circulation of air over the skin, reducing the possibility of heat-stress. A small gap may be regarded as a continuous annulus of less than 25 mm and optionally less than 15 mm around the circumference of the leg. The base layer leggings 3 are provided with a high waist with an elasticated waist band 9, with a pair of spaced annular neoprene sealing bands 9′ and 9″. In use, the base layer top 2 is tucked in between the torso and elasticated waist band 9 of the base layer leggings 3. The double neoprene seal seals against the base layer top to inter alia inhibit an entrance for smoke to pass between the skin and the base layer and to inhibit creating a continuous chimney like flow path along which would facilitate flow of smoke between the base layer and the skin. A line of stitching 10′ is provided along an inner side of leg portions 7 and 8 and meet at a crotch. The stitching 10′ facilitate providing a consistent annular gap between the legs of the firefighter and the composite fabric. The stitching 9′ may form a ladder pattern, a series of H shapes to facilitate the shape of the leggings 3.

[0052] The base layer top 2 has a collar 11 and shoulder portions 12 and 13, chest portion 14, over length sleeves 15 and 16. The base layer top 2 hangs over the shoulders and chest and loosely fits around the waist and arms. No gap between the base layer top 2 and the skin is provided over the shoulder and chest. A small annular gap may provide additional insulation from excessive ambient heat and improve circulation of air over the skin around the waist region of the torso 17 and around the arms, reducing the possibility of heat-stress. A small gap may be regarded as less than a continuous annulus of 25 mm and optionally less than 15 mm around the circumference of the waist and arms. A line of stitching 11′ is provided substantially concentric with the collar 11. The stitching 10′ may facilitate providing a flat contact area with a neckline of the firefighter 4. The stitching 10′ may increase the rigidity of the composite fabric in the area about the neck. A line of stitching 14′ and 14″ runs down each front-side of the base layer top 2 which may facilitate a contact fit with the shoulder and upper chest area 14E of the firefighter 4 and a loose fit area 14A over the stomach area. The loose fit area may provide a consistent gap around the stomach area and may provide a consistent gap around the lower back area and may provide a consistent annular gap about the lower torso of the firefighter. The stitching 11′, 14′ and 14″ may form a ladder pattern, a series of H shapes to facilitate the shape of the leggings 3.

[0053] A line of stitching 15′ and 16′ is provided substantially along a substantially portion of respective sleeves 15 and 16. The lines of stitching 15′ and 16′ may facilitate providing a flat contact area about the shoulder of the firefighter 4. The lines of stitching 15′ and 16′ may increase the rigidity of the composite fabric in the area about the neck. The over length portions 19 and 20 of the sleeves 15 and 16 comprise thumb holes 18 provide protection over palms and backs of the hands. The over length portions 19 and 20 may also provide a tortuous path for any smoke contaminated air to pass between the hands and the sleeves 15 and 16 of the base layer top 2. Each base layer may be tailored to each individual firefighter 4.

[0054] The base layer 1 is made from a composite fabric 100 shown in FIG. 2. The composite fabric 100 comprises three layers: a breathable membrane layer 101 sandwiched between an inner fabric layer 102 and outer fabric layer 103. The inner fabric layer 102 is laminated to a first side of the breathable membrane layer 101 with a polyurethane 104. The outer fabric layer 103 is laminated to an opposing side of the breathable membrane layer 101 with a polyurethane 105. The composite fabric 100 may have elastic properties to allow the firefighter to move in an agile fashion whilst providing a close fit, providing a small gap or be tight against the skin of the firefighter. Alternatively, the base layer has very limited elastic properties to maintain consistent breathability characteristics. In the latter case, it may be preferred to have each base layer tailored to each firefighter.

[0055] During manufacture, the composite fabric 100 is cut to a pattern using conventional techniques, such as scissors or punches and machine sewn along seams using a fire-resistant thread 10.

[0056] The inner and outer fabric layers 102 and 103 may be of the same fabric, which also preferably has similar elasticity characteristics to the breathable membrane 101. Thus, the elasticity of the inner and outer layers is identical, which may help maintain a bond with the breathable membrane 101. A piece of fabric 106 is shown in FIG. 3A which may be used for the inner and outer fabric layers 102 and 103.

[0057] The fabric 106 may be woven from fire-retardant yarn 107. Optionally, the yarn 107 comprises polyester filaments (optionally 75% to 100% of the filaments are polyester). Optionally, the filaments are discontinuous fibres which are spun into the yarn, optionally using conventional cotton spinning techniques. This may provide a more natural, cotton-like feel. The discontinuous fibres are of random lengths, such as between 20 mm and 1000 mm. The polyester filaments or the yarn may be coated, injected, impregnated or dipped in a fire-retardant liquid, such as a Toray fire-retardant, a fire-resistant epoxy or polyolefin resin composition or other suitable fire-retardant.

[0058] As shown in FIG. 3A, the yarn 107 is woven into the fabric 106 and used for the inner and outer fabric layers 102 and 103. The woven fabric 106 comprises a warp 108 and a weft 109, defining openings 110. The warp and weft may be at right-angles to each other, but may be up to 45 degrees to each other. The fabric is preferably between 50 gsm (grams per square metre) and 200 gsm and optionally between 75 and 125 gsm and optionally Jersey 100 gsm on a gauge 28 with a yarn numbered Ne (English Cotton Count) of 30. The fabric may alternatively be 90 gsm with a yarn number Ne 40 or may have a yarn number between Ne 30 and Ne 40.

[0059] As shown in FIGS. 3B and 3D, there are approximately thirty threads of warp 108 per 10 mm and thirty threads of weft 109 per 10 mm. However, it is envisaged that anywhere between ten and one hundred threads of warp 108 per 10 mm and weft 109 per 10 mm would be sufficient and may between fifteen and fifty threads of warp 108 per 10 mm and weft 109 per 10 mm would be sufficient and may between thirty and forty threads of warp 108 per 10 mm and weft 109 per 10 mm would be sufficient.

[0060] As shown in FIG. 3E, the fabric 106 is considerably thicker than the membrane 101. The outer fabric layer 103 may be thicker than the inner fabric layer 102, such as between two and five times thicker and may be between two and three times thicker. This may improve moisture release from the base layer 1. Alternatively, the inner fabric layer 102 may be thicker than the outer fabric layer 103, such as between two and five times thicker and may be between two and three times thicker. This may improve moisture gathering from the skin of the firefighter to the base layer 1. The outer fabric layer 103 may be approximately 1.5 mm thick and the inner fabric layer 102 may be approximately 0.5 mm thick. Alternatively, the inner fabric layer 102 may be approximately 1.5 mm thick and the outer fabric layer 103 may be approximately 0.5 mm thick. The membrane 101 may be in the order of 0.1 mm thick.

[0061] The yarn 106 may have the following characteristics:

TABLE-US-00001 TESTING DATA OF FLAME RETARDANT FIBER 1.56DTEX/38 MM YGN443 1 Dry tenacity 5.39 ± 10% (Breaking Strength) cN/dtex 2 Dry elongation 25.9 ± 10% (Elongation at Break) % 3 Deviation of linear density −1.9 ± 10% (Line Density Deviation Rate) % 4 Deviation of length −2.4 ± 10% % 5 Content of double-length fibres  0.8 ± 10% mg/100 g 6 Defects Content  0.5 ± 10% mg/100 g 7 No. of crimps 10.8 ± 25% No./25 mm 8 Crimp ratio 14.7 ± 25% (Curl Rate) % 9 Shrinkage in 180° C. hot air  7.9 ± 10% (180° C. dry heat shrinkage rate) % 10 Resistivity  0.1 ± 100% (Specific Resistance) Ω .Math. cm

[0062] FIG. 4 shows the breathable membrane 101, which is a flexible membrane with small pores 101′ to inhibit particles generally found in smoke to pass through, but which will allow sweat to pass through. This may be achieved by the breathable membrane 101 being microporous and may be hydrophilic and may be made from a polymer. This may facilitate moisture to pass through the membrane, whilst utilising small pores, which will not allow particles found in smoke to pass across the membrane 101. The membrane may thus act as a filter to inhibit ingress of particles found in smoke whilst allowing egress of moisture from the skin of a firefighter.

TABLE-US-00002 TEST PROPERTY SPECIFICATION METHOD Thickness Range 22-28 BS EN ISO (μ) Typical 25 2286-3: 1998 (STM 229) Weight Range 34-42 BS EN ISO (g/m2) Typical 38 2286-2: 1998 (STM 230) W.V.T. (g/m.sup.2/24 hr) Min 550 ± 10% ASTM E96: 95, (Water Vapour Typical 630 ± 10% Procedure B Transmission) (STM 201) W.V.P. Index (%) Min  74 ± 10% BS 7209: 1990 (Water Vapour Typical  80 ± 10% (STM 200) Permeability) Hydrostatic Initial 700  BS3424, Part Head (cm) x3 washes 700  26: 1990, Method 29A (STM 241) Shrinkage L Max   2.5 STM 205 @160° C. (%) X Max   2.5 Load @ 25% Min 0.65 ± 10%  BS ISO 37: Elongation (N/cm) 2011 (STM 007) Tensile Min  3.7 ± 10% BS ISO 37: Strength (N/cm) 2011 (STM 007) Elongation Min 275 ± 10% BS ISO 37: at Break (%) 2011 (STM 007) Vertical No drip or 13 cm ± 20%  FTM Standard Burn Test afterglow 191A, Burn length Method 5903-1 max: (STM 112) Mean: 10 cm ± 20%  UV Stability: Min: 50 STM 116 Retained Tensile Strength (%) and Elongation at Break (%)

[0063] FIG. 3B shows a perspective view showing the outer fabric layer 103 laminated to a first side of the breathable membrane 101. An inner fabric layer 102 is optionally laminated to the opposing side of the breathable membrane 101, although this is not shown in this view.

[0064] In use, moisture from the skin passes through openings 110 in the inner fabric layer 102, swiftly removing moisture from the skin. The breathable membrane 101 allows moisture to pass through micropores in the hydrophilic membrane 101 and out into the openings 110 in the outer fabric layer 103. Air circulating between the base layer 1 and out garments flows over the openings 110, sucking the moisture therefrom. The openings 110 in the inner and outer fabric layers 102 and 103 are considerably larger than the micropores in the breathable membrane 101.

[0065] Referring to FIG. 4A, the inner fabric layer 102 may comprise short discontinuous polyester fibres 140. The short discontinuous polymer fibres 140 or the yarn 107 made up of these fibres may act as wicks, so that when the fabric is used as an inner fabric layer 102, sweat from pores 143 is drawn from the skin 141 and hairs 142 on the skin and along and between the short polyester fibres 140. This wicking effect, (which may be similar to capillary action and may utilise surface tension to pull the sweat away from the skin) moves the sweat away from the skin, through openings 110 in the inner layer of fabric 102 to the breathable membrane 101. The pores in the breathable membrane 101 are very small, but the hydrophilic breathable membrane 101 helps draw the water through the membrane. Any particles in the sweat may or may not be drawn through the breathable membrane 101. Movement of the wearer may facilitate movement of the sweat, providing a pumping action by differential movement between adjacent fibres and adjacent yarn 107 in the warp 108 and weft 109. The sweat is then conveyed away from the breathable membrane 101 by the same wicking action in outer fabric layer 103, drawing the sweat away from the breathable membrane 101 along short discontinuous polyester fibres 145. The droplets of sweat on the short discontinuous polyester fibres 145 are drawn off by warm air in the air gap or annulus 146 between the base layer 1 and an outer garment 147 circulates in the gap. The outer surface of the outer fabric layer 103. Warm air in the gap 146 may be warmer than the skin 141 and thus create a pressure differential which may facilitate movement of sweat away from the skin and across the breathable membrane 101.

[0066] The breathable membrane 101 may be a single layer of Poly Tetra Fluoro Ethylene (PTFE). Optionally, the breathable membrane 101 is a single layer of an expanded polytetrafluoroethylene (ePTFE) and may form a matrix. The matrix may form openings suitable to allow air and/or moisture to pass across the membrane. Optionally, the breathable membrane 101 comprises at least one of: Poly Tetra Fluoro Ethylene (PTFE); expanded polytetrafluoroethylene (ePTFE), polyvinyl chloride (PVC); polyurethane (PU); polyaxnide polyester; or a blend thereof. The membrane incorporates pores or micropores to allow moisture to pass through the membrane, which may be formed by the matrix.

[0067] The breathable membrane 101 and/or woven fabric layers 102, 103 may be coated. The coating may be a polymer coating. The coating may comprise 15-20%, optionally 16.4% Polyvinyl alcohol (such as a mixture of ⅓ Airvol 103 and ⅔ of Airvol 125), 1 to 10%, optionally 5% Polyvinyl acetate (Airflex 410), 10 to 20% optionally 16.4% Polyethylenimine (Lupasol F WF from BASF); about 1% Cross-linking agent CX-100, about 0.9-1% Surfactant and defoamer Surfynol 104H and 50 to 70%, optionally 60.3% Water.

[0068] The composite material of the invention is light weight and flexible, which does not significantly affect body movement. The breathable membrane 101 may be the membrane element of one of the moisture barriers sold under the trade mark STEDAIR PREVENT, STEDAIR GOLD or STEDAIR 3000 by Stedair, Inc.

[0069] Referring to FIG. 5A, there is shown an apparatus used in the manufacture of the composite fabric 100, the apparatus generally identified by reference numeral 200. The apparatus 200 comprises a roll 201 of fabric 106. A tensioner or drive roller 202 may be used to control the speed of rollout and/or tension in the fabric 106 which may inhibit wrinkling. The fabric 106 may pass over a guide roller 203 and under an engraved roller 205. The engraved roller 205 is coated with a hotmelt polyurethane 206. The hotmelt polyurethane is stored in a 200 litre drum 207. The hotmelt polyurethane is highly viscous at room temperature. The hotmelt polyurethane is heated and flows from the drum 207 into a sump formed in a nip between adjacent rollers 208, 209. Roller 208 rotates in a clockwise direction and roller 209 rotates in an anticlockwise direction. Roller 208 picks up a thin layer of polyurethane from the sump and passes it on to coat the engraved roller 205 rotating anticlockwise. Any or all of the rollers 208, 209 and engraved roller 205 may be driven by a motor M.

[0070] The engraved roller may have any suitable relief pattern engraved thereon, such as the pattern 210 shown in FIG. 6. This pattern comprises a series of ridges 211 and valleys 212 which run parallel to each other and may be arranged radially to apply the hotmelt polyurethane 206 is continuous lines which run in the direction of travel of the fabric 106 through the apparatus. Alternatively, the series of parallel ridges 211 and valley 212 may be arranged at an angle to the direction of travel of the fabric 106 through the apparatus to apply discontinuous lines of hotmelt polyurethane to the fabric 106. The ridges 211 may be spaced 1 to 2 mm apart to provide a valley 212 of width 1-2 mm across. The width of each ridge top may be approximately 1 mm.

[0071] Any or all of the rollers 208, 209 and engraved roller 205 may be heated to maintain the polyurethane at a desired application temperature, which may be between 100 and 180 degrees Celsius and preferably between 110 and 130 degrees Celsius.

[0072] The hotmelt polyurethane 206 may be a moisture curing hotmelt polyurethane adhesive with a temperature resistance of between −30 and 130 degrees Celsius and an application temperature of 120 degrees Celsius. The hotmelt polyurethane 106 may be applied at a rate of between 6 and 30 grams per square metre and optionally 10 g per square metre. Initial cure time may be in the order of 30 minutes.

[0073] The engraved roller 205 applies the hotmelt polyurethane 206 to the fabric 106 in thin lines. The fabric may pass over a further roller 215 and into a nip between rollers 216 and 217. Either or both of rollers 216, 217 may be driven or tensioned by a respective motor M. A roll 220 of breathable membrane 101 passes into the nip between the rollers 16, 217 over the hotmelt polyurethane applied to the fabric 106, laminating the breathable membrane 101 to the fabric 106. The laminated fabric 120 wound on to roll 221. The roll 221 may be driven or tensioned by a motor M.

[0074] A computer controller 225 is used to control the speed and tension in the rolls and rollers 201, 221, 208, 209, 205, 216, 217 of the apparatus 200.

[0075] When desired, the apparatus 200 is shut down and roll 220 is removed and left for the hotmelt polyurethane to cure which may be for between one hour and several days, and may be 48 hours. Roll 221 removed and placed where roll 220 was and unfurled to the nip between rollers 216 and 217, as shown in FIG. 5B, The apparatus 200 is set running to apply the laminated fabric 120 to the hotmelt glue applied to fabric 106, as described above with reference to FIG. 5A, to make a composite fabric 100 of the invention, which is wound on to roll 222. With correct machine settings up to 70% open area possible for breathability, so the composite fabric 100 maintains most of its breathability. Technique relays may be used on geometry of fabrics to remove adhesive where it touches.

[0076] FIGS. 7A and 7B there is shown a further alternative apparatus used in the manufacture of the composite fabric 100, the apparatus generally identified by reference numeral 300. The apparatus 300 is generally similar to the apparatus 200, utilizing a similar arrangement of rollers, but within an upright apparatus. The apparatus may also comprise a doctor blade to facilitate spreading the hotmelt polyurethane after application using the engraved roller and before the fabric 106 enters the nip to apply the breathable membrane 101. The apparatus 300 may comprise a close couple 3 roller configuration steel-steel-steel, with unwinds with tension control, laps rolls, tension sensing winder with an engraved roller, form Trihelical 3 start multi helix depth 100 micron approximately and 28 mesh. Design weight 10-20 gam.