Classifications

• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
  • D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
  • D04H3/10—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with bonds between yarns or filaments made mechanically
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04B—KNITTING
  • D04B21/00—Warp knitting processes for the production of fabrics or articles not dependent on the use of particular machines; Fabrics or articles defined by such processes
  • D04B21/14—Fabrics characterised by the incorporation by knitting, in one or more thread, fleece, or fabric layers, of reinforcing, binding, or decorative threads; Fabrics incorporating small auxiliary elements, e.g. for decorative purposes
  • D04B21/16—Fabrics characterised by the incorporation by knitting, in one or more thread, fleece, or fabric layers, of reinforcing, binding, or decorative threads; Fabrics incorporating small auxiliary elements, e.g. for decorative purposes incorporating synthetic threads
  • D04B21/165—Fabrics characterised by the incorporation by knitting, in one or more thread, fleece, or fabric layers, of reinforcing, binding, or decorative threads; Fabrics incorporating small auxiliary elements, e.g. for decorative purposes incorporating synthetic threads with yarns stitched through one or more layers or tows, e.g. stitch-bonded fabrics
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2403/00—Details of fabric structure established in the fabric forming process
  • D10B2403/02—Cross-sectional features
  • D10B2403/024—Fabric incorporating additional compounds
  • D10B2403/0241—Fabric incorporating additional compounds enhancing mechanical properties
  • D10B2403/02412—Fabric incorporating additional compounds enhancing mechanical properties including several arrays of unbent yarn, e.g. multiaxial fabrics

Definitions

• the present invention relates to stitch-bonded fabrics which are especially suitable for reinforcing the backings of coated abrasives.
• Stitch-bonded fabrics in general have been known for at least the last twenty years. However, it has not been appreciated that such fabrics could confer special advantages when used as the reinforcing substrate for coated abrasive backings. Thus no fabrics explicitly suitable for such purposes were known to the applicant from prior art.
• the preferred machines for the fabrics of the present invention are those of the Malimo type.
• the description of mechanical characteristics of Malimo machines given immediately below condenses from this publication those characteristics believed by the applicant to be most relevant to design of fabrics suitable for use in coated abrasives.
• Malimo machines have three principal mechanical characteristics which limit the variety of fabric constructions available from them. The first of these limits is provided by a group of several matched mechanical structures which fix a maximum "gauge" or number of yarns per 25 mm of width for the warp yarn and stitching yarn assemblies which can be used with the machine. Twelve possible gauges from 3 to 22 are available from the manufacturer.
• the second of the principal mechanical limitations of the Malimo machine is its stitch length. This can be adjusted in 20 steps within a range of 0.7 to 5 mm. It should be noted that this nominal "stitch length" is actually the projected length in the direction of the warp yarns. When a tricot style stitch is used, as was the case for the fabrics to be described here, the actual spatial orientation of the stitch is at a substantial angle to the warp yarns, and the actual length is correspondingly longer than the nominal length. In addition, because the stitch yarns form loops, the length of yarn consumed for each stitch is generally considerably longer than either the nominal or actual lengtho With the fabrics described below, stitch yarn length consumption was about four times warp yarn length consumption.
• hooks which hold the fill yarns in tension until they can be stitched to the warp.
• Hook units are available in linear densities from 8 to 48 hooks per 25 mmo Under the normal conditions of use as contemplated by the instructions furnished by the manufacturer, no more than one bend of fill yarns around each hook is accommodated during fabric assembly operations.
• this result is preferably attained by the use of warp arrays with yarns of high denier, high tenacity synthetic multifilament or glass in a number of at least 12 yarns per 25 mm of fabric width, fill yarn arrays of smaller denier texturized multifilament or staple synthetic yarn in a number of at least 64 per 25 mm of fabric length, and by fine denier stitch yarns with a breaking strength of at least 0.007 dekanewtons per denier.
• Malimo machines with model numbers 14010 or 14011 were preferred for making the fabrics of the present invention. Liba machines and Raschel knitting machines make equally satisfactory fabrics but are limited to lower speeds of operation and thus are less economicalo
• high tenacity yarns are very effective in providing warp tensile strength, they provide relatively little cover or opportunity for facile mechanically aided adhesion of cloth finishing adhesives, which are needed to complete the final backings on which coated abrasives are to be made. I have found it possible to compensate for these deficiencies by using high linear densities of relatively small spun staple or textured multifilament fill yarns. The greater surface area per unit mass of these yarns, as compared with the warp yarns, provides superior possibilities for mechanical adhesion of the finishing adhesives and ready achievement of adequate cover, when combined with suitable processing techniques for the finishing.
• Hooks 5 mm high were used for all constructions shown except those with 500 denier fill yarns; with these larger yarns the 7 mm size hooks gave better results.
• Medium size sliding needles and closing wires, 1.8 mm diameter stitching yarn guide holes, and round rather than oval retaining pins among the choices offered by the manufacturer were preferred for the fabrics shown.
• Both fill yarn carrier reeds and hook carriers with 32 openings per 25 mm were used for fabrics with 64 or 128 fill yarns per 25 mm, while carrier reeds and hook carriers with 24 openings per 25 mm were used for achieving 96 fill yarns per 25 mm.
• stitch yarns Additional possibilities for adhesion and cover are provided by the stitch yarns.
• synthetic multifilament yarns in deniers from 70 to 220 very satisfactory as stitch yarns for these fabrics.
• the primary requisite from the stitch yarn for the ultimate coated abrasive is sufficient strength to resist rupture between the warp and fill arrays of yarns under use conditions.
• 70 denier polyester yarn with a breaking strength of at least 0.008 daN per denier was found to be adequate for most purposes.
• Each stitch normally forms a loop around only one warp yarn (unless more than one yarn is fed through a single opening as noted above), but the number of fill yarns inside a stitch loop can vary from none to several, depending on how many fill yarns happen to occupy the space inside the fixed stitch length.
• a random pattern of short, relatively open spaces may often be observed in the fabric produced, as a result of greater or lesser than average number of fill yarns being caught inside the loops of particular stitches. Within the limits described herein, this pattern has not been found to cause any difficulty in the coated abrasives produced with such fabrics as substrates.
• the cover factor for the fill yarn array noted in Table 1 is the same as the value often called "fractional coverage" by others; i.e., the fraction of the total area enclosed within the borders of a sample of the fabric which is covered by the fill yarn array therein. In principle, this value could be easily calculated from a knowledge of the linear density and the diameter of the fill yarns: If n is the number of fill yarns per unit length of the fabric and d is the diameter of each yarn in the same units, the cover factor is 100nd%. In practice, measuring the diameter of yarn precisely is very difficult, and in conformance with common textile art practice, the cover factor used herein was determined by an indirect calculation making use of the density and denier size of the yarn. From the definition of denier (cf.
• the density of a yarn in turn depends on the fundamental density of the fibers which compose it and on how tightly the fibers are packed.
• the latter characteristic of the yarn is quantified as a packing fraction, which when multiplied by the fiber density gives the yarn density.
• the following values in gm/cm for fiber density of the fill yarn fibers listed in Table 1 were taken: polyester, 1.3; cotton, 1.56; and polyamide, 1.14. Packing fractions taken were: textured polyamide, 0.80; textured polyester, 0.70; staple polyester, 0.59; and mixed yarn, 1.0.
• the fabrics specified in Table 1, or other fabrics constructed using the same principles, may be finished in a variety of ways to make suitable backings for coated abrasives. These backings in turn may be coated with any of the variety of maker adhesives, abrasive grits, and sizer adhesives, well known in the art. Some specific examples of these ways to use my invention are given below, and others will be readily apparent to those skilled in the art of manufacturing coated abrasives, upon considering the teachings herein in combination with those of the aforesaid copending application.
• Standard sizing rolls are employed to apply the following composition in the amount of 40 to 60 grams per square meter.
• the fill yarn side of the fabric was facing up.
• the fabric Upon completion of the application of the saturant the fabric is dried on a tenter frame for at least 3 minutes in a hot air oven in which the temperature in the entry zone is 96°C., and the temperature at the exit zone is 177°C. A tension of at least 3.5 Newtons per centimeter (N/cm) of width is maintained on the fabric during its travel through the oven. This process not only dries the saturant but also heat-sets the fabric.
• composition of the frontfill coating applied to the fill yarn side in this example, but which can instead be applied to the warp yarn side if desired, is as follows:
• the front fill coating composition is applied with a knife in the amount of 150-165 dry grams per square meter (gm/m 2 ), and water may be added as necessary to maintain the required viscosity for proper coating.
• the coated cloth is again dried on a tenter frame with a tension of at least 3.5 N/cm of width by passing through a hot air oven in which the entry temperature is 96°C. and the exit zone temperature is 150°C.
• composition is applied by knife coating in the amount of 140-165 gm/m 2 and dried in an oven having an entry zone temperature of 66°C. and an exit zone of 93°C.
• a suitable formulation to be applied to the frontsized side of the backing is as follows:
• a size coat (about 160 gm/m2 dry) of the same composition as the maker coat, except of lesser viscosity, is then applied according to usual techniques.
• the wet adhesive layer is then dried: 25 minutes at 52°C., 25 minutes at 57°C., 18 minutes at 82°C., 25 minutes at 88°C., and 15 minutes at 107°C., after which final cure at 110°C, for 8 hours is given.
• the coated abrasive material is then ready to be converted according to usual techniques, into belts, discs, and other desired abrasive products.
• Cloth of the construction described with the identifying number 3 in Table 1 was coated by the dip and squeeze method with a two roll padder, using the following saturant:
• the fabric was held in a tenter frame to prevent width shrinkage and dried by passing for 3.75 minutes through an oven with an entry zone temperature of 135°C. and an exit zone temperature of 240°C. Sufficient saturant to give a dry add-on of 52 + 7 gm/m 2 was used.
• the ingredients are added in the order listed, with continuous stirring.
• the adhesive is coated on the saturated fabric by a knife over roll technique in sufficient quantity to give 175-225 gm/m 2 of adhesive after drying.
• the coated fabric is again tentered to eliminate any possible loss in width and is passed for 3.75 minutes through an oven with an entry zone temperature of 65°C. and an exit zone temperature of 107°C.
• the backfilled fabric was then frontfilled on the opposite side from backfilling with the same adhesive composition as used for backfilling, in sufficient quantity to give 120-180 gm/m 2 of dried frontfill. Coating of frontfill could be accomplished either by knife or roll techniques with approximately equal facility. Oven conditions for drying frontfill were the same as for backfill, but satisfactory results in drying at this stage could be achieved without tentering if desired.
• the finished backing was then ready for making and sizing steps to convert it to a coated abrasive by conventional means as described briefly in Example 1.
• Table 2 shows physical properties of the coated abrasives prepared in Examples 1-3 and compares them against the same measurements on commercial coated abrasive products with woven cloth backings.
• the tensile strength of the products described herein is closely comparable to the commercial products for Example 1 and superior for Examples 2 and 3.
• the burst strength which is generally correlated with resistance to many environmental hazards during use of coated abrasives, is quite notably superior for Example 2 and closely comparable for the others. Elongation is higher for Examples 1 and 2 but lower or comparable for Fabric 3.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Mechanical Engineering (AREA)
• Polishing Bodies And Polishing Tools (AREA)
• Woven Fabrics (AREA)
• Knitting Of Fabric (AREA)
• Treatment Of Fiber Materials (AREA)
• Details Of Garments (AREA)
• Measuring Fluid Pressure (AREA)
• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)

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Publications (3)

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Cited By (7)

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Citations (1)

• 1982
  • 1982-05-21 CA CA000403563A patent/CA1215242A/en not_active Expired
  • 1982-06-24 ZA ZA824506A patent/ZA824506B/xx unknown
  • 1982-06-25 AT AT82105651T patent/ATE24341T1/de not_active IP Right Cessation
  • 1982-06-25 DE DE8282105651T patent/DE3274749D1/de not_active Expired
  • 1982-06-25 DE DE198282105651T patent/DE73313T1/de active Pending
  • 1982-06-25 EP EP82105651A patent/EP0073313B1/de not_active Expired
  • 1982-06-29 AU AU85435/82A patent/AU557338B2/en not_active Expired
  • 1982-07-21 MX MX193684A patent/MX171960B/es unknown
  • 1982-07-27 ES ES514405A patent/ES8502176A1/es not_active Expired
  • 1982-07-27 JP JP57129728A patent/JPS5841951A/ja active Granted
  • 1982-07-27 BR BR8204384A patent/BR8204384A/pt not_active IP Right Cessation
  • 1982-07-27 DD DD82241982A patent/DD202320A5/de unknown
  • 1982-07-27 YU YU01632/82A patent/YU163282A/xx unknown

Patent Citations (1)

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