MXPA97004659A - Method for producing a non tram tissue - Google Patents

Abstract

A process is provided which comprises the step of subjecting a newly produced spunbond fabric to a heated flow of high air flow rate through essentially the width of the fabric to join the fibers of the fabric together very slightly. Such a union must be the minimum necessary in order to satisfy the needs of an additional procedure but not to detrimentally affect the tissue. The fibers of the fabric may be monocomponent or biconstituent and the fabric must be substantially free of adhesives and not subjected to compaction rolls.

Description

METHOD FOR PRODUCING A NON-TRAMED TISSUE This invention relates to the field of non-woven fabrics or fabrics and their manufacture. More particularly, this relates to such non-woven fabrics which are composed of at least one layer of fibers or filaments joined by spinning. Such fibers are commonly composed of a thermoplastic polymer such as polyolefins, for example, polypropylene, polyamides, polyesters and polyethers.

The uses for such fabrics are in such applications as diapers, products for women's hygiene and barrier products such as medical gowns and surgical drapes.

In the process of producing a woven fabric by non-woven yarn, it is a standard practice to increase the integrity of the fabric by some method for further processing. The increase in tissue integrity is necessary in order to maintain its shape during the post-training process. Generally, compaction is used immediately after tissue formation.

The compaction is achieved by "the compaction rollers" which squeeze the fabric in order to increase its self-adherence and therefore its integrity. The compaction rollers perform this function well but they have a number of disadvantages. One such disadvantage is that the compaction rollers actually compact the fabric, using a decrease in the volume or elevation in the fabric which may be undesirable for the intended use. A second more serious disadvantage for the compaction rollers is that the fabric sometimes wraps around one or both of the rollers causing a closing of the fabric production line to clean the rollers, with the obvious accompanying loss in the production during the time dropped. A third disadvantage of the compaction rollers is that if a slight imperfection occurs in the formation of the fabric, such as a fall of the polymer that is being formed in the fabric, the compaction roller may be forced to fall within the band. foraminous, on which most of the tissues are formed, causing an imperfection in the band and ruining it.

Therefore, it is an object of this invention to provide a method for providing a non-woven fabric with sufficient integrity to further process without the use of compaction rollers or adhesives and which is suitable for use in the continuous industrial production operation.

The present invention seeks to overcome the aforementioned problems. The object is solved by the method of producing a nonwoven fabric according to the independent clause 1 and also by the use of the fabric according to clause 17.

The advantages, features, aspects and additional details of the invention are apparent from the dependent claims, from the description and from the accompanying drawings. The claims are intended to be understood as a first non-limiting approach to defining the invention in general terms.

According to one aspect of the present invention there is provided a process which comprises the step of subjecting a newly produced yarn-bonded fabric to a heated stream of high air flow rate through essentially the width of the fabric to join very slightly the tissue fibers together. Such a union must be of the minimum necessary in order to satisfy the needs of the additional processing without detrimentally impacting the properties of the finished fabric. The fibers of the fabric must be monocomponent or biconstituent and the fabric must be essentially free of adhesives and not subject to the compaction rollers.

The inventors have surprisingly discovered that a suitably controlled HAK, operating under the conditions presented herein, can serve to lightly bond a spunbonded fabric of monocomponent and biconstituent fibers without detrimentally affecting the properties of the fabric and even improving said tissue properties, thus making the need for the compaction rollers obvious. The invention will be better understood with reference to the following description of the embodiments of the invention taken in conjunction with the accompanying drawings, wherein: Figure 1 is a schematic illustration of an apparatus which can be used to perform the method and to produce the non-woven fabric of the present invention.

Figure 2 is a cross-sectional view of a device which can be used in the practice of this invention.

Figures 3 and 4 are micrographs of electronic analysis of two tissues made according to the invention.

As used herein the term "nonwoven fabric or fabric" means a fabric having a structure of individual fibers or threads which are interleaved, but not in an identifiable manner as in a woven fabric. formed from many processes such as, for example, meltblowing processes, spinning bonding processes, and bonded and carding processes.The basis weight of non-woven fabrics is usually expressed in ounces of material per square yard (osy ) or grams per square meter (gsm) and the fiber diameters are usually expressed in μm (Note that to convert from osy to gsm, multiply osy by 33.91).

As used herein the term "icrofibers" means small diameter fibers having an average diameter no greater than about 75 μm, for example, having an average diameter of from about 0.5 μm to about 50 μm, or more particularly, microfibers that can have an average diameter of from about 0.5 μm to about 40 μm. Another frequently used expression of fiber diameter is denier, which is defined as grams per 9000 meters of a fiber. For example, the diameter of a given polypropylene fiber in μm can be converted to denier by quadrature and multiplying the result by 0.00629, therefore, a polypropylene fiber of 15 μm has a denier of about 1.42 (152 X 0.00629 = 1.415).

As used herein, the term "spunbonded fibers" refers to fibers of small diameter which are formed by extruding the melted thermoplastic material as filaments of a plurality of usually circular and thin capillary vessels of a spinner organ having the diameter of the extruded filaments then being rapidly reduced as by the process shown, for example, in U.S. Patent No. 4,340,563 issued to Appel et al., and in U.S. Patent 3,692,618 issued to Dorschner et al. , and in U.S. Patent No. 3,802,817 issued to Matsuki et al., in U.S. Patent Nos. 3,338,992 and 3,341,394 issued to Kinney, in U.S. Patent Nos. 3,502,538 granted to Levy, in the patent of the United States of North America No. 3,502,763 granted to Hartman, and in the patent of and the United States of America No. 3,542,615 granted to Dobo and others. Spunbond fibers are generally continuous and have diameters greater than 7 μm, more particularly between about 10 and about 30 μm. Spunbonded fibers are not generally sticky when they are deposited on the collector surface.

As used herein the term "meltblown fibers" means the fibers formed by extruding a melted thermoplastic material through a plurality of capillary matrix vessels, usually circular and thin as melted threads or filaments into gas streams. (for example, air) at a high converging speed which attenuate the filaments of the melted thermoplastic material to reduce its diameter, which can be a microfiber diameter. Then, the melt-blown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a meltblown fabric of fibers randomly discharged. The fibers formed by meltblowing are generally sticky when they are deposited on the collecting surface. Such a process is described, for example, in United States Patent No. 3,849,241 issued to Butin. The fibers formed by meltblowing are microfibers which can be continuous or discontinuous and are generally smaller than 10 μm in diameter.

As used herein the term "polymer" generally includes but is not limited to, homopolymers, copolymers, such as, for example, block, grafted, random and alternating copolymers, thermopolymers, etc. and mixtures and modifications thereof. . In addition, unless specifically limited otherwise, the term "polymer" will include all possible molecular geometric configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic and random symmetries.

As used herein the term "machine direction" or "MD" means the length of a fabric in the direction in which it is produced. The term transverse direction to the machine or "CD" means the width of the fabric, for example, an address generally perpendicular to the MD.

As used herein the term "monocomponent" fibers refers to fibers formed of only one polymer. This does not mean that fibers formed from a polymer to which small amounts of additives for coloring, antistatic properties, lubrication, hydrophilicity, etc. have been added are excluded. These additives, for example, titanium dioxide for coloration, are generally present in an amount of less than 5 percent by weight and more typically of about 2 percent by weight.

As used herein the term "bicomponent fibers" refers to fibers which have been formed from at least two extruded polymers from separate extruders but have been spun together to form a fiber. The polymers are arranged in distinct zones essentially constantly placed across the cross section of the bicomponent fibers which extend continuously along the length of the bicomponent fibers. The configuration of such bicomponent fiber can be, for example, a pod / core arrangement where one polymer is surrounded by another or can be a side-by-side arrangement or an arrangement of "islands in the sea". The bicomponent fibers are shown in U.S. Patent No. 5,108,820 issued to Kaneko et al., In U.S. Patent No. 5,336,552 issued to Strack et al., And in European Patent 0586924. If two polymers are used they may be present in proportions of 75/25, 50/50, 25/75 or any other desired proportions.

As used herein the term "biconstituent fibers" refers to fibers which have been formed from at least two extruded polymers from the same extruder as a mixture. The term "mixture" is defined below. The biconstituent fibers do not have the various polymer components arranged in distinct zones relatively constantly placed across the cross-sectional area of the fiber and the various polymers usually not continuous along the entire length of the fiber, instead of this usually forming fibrils that start and end in random form. Biconstituent fibers are sometimes also referred to as multi-constituent fibers. Fibers of this type are discussed in, for example, United States Patent No. 5,108,827 issued to Gessner. Bicomponent and biconstituent fibers are also discussed in the text mixtures and polymer compounds by John A. Manson and Leslie H. Sperling, copyright 1976 by Plenu Press, a division of Plenum Publishing Corporation of New York, IBSN 0-306 -30831-2, pages 273 to 277.

As used herein the term "mixtures" means a combination of two or more polymers while the term "alloy" means a subclass of mixtures wherein the components are immiscible but have been compatibilized. "Miscibility" and "immiscibility" are defined as mixtures having negative and positive values, respectively, for the free energy of mixing. In addition, "compatibilization" is defined as the process for modifying the interfacial properties of an immiscible polymer mixture in order to make an alloy.

As used herein, through air bonding or " " means a process of joining a non-woven bicomponent fiber fabric which is at least partially wound around a perforated roll which is encased in a cover. The air which is hot enough to melt one of the polymers from which the fibers of the fabric are made is forced from the cover, through the fabric and into the perforated roller. The air speed is between 30.48 m and 152.4 m per minute and the dwell time can be as long as 6 seconds. The melting and resolidification of the polymer provides the bond. The continuous air union has restricted variability and is generally seen as a second step joining process. Since the continuous air union requires the melting of at least one component to achieve the bond, it is restricted to bicomponent fiber fabrics.

As used herein, the term "medical product" means surgical gowns and wipes, face masks, head covers, shoe covers, wound dressings, bandages, sterilization wraps, cleansers and the like.

As used herein, the term "personal care products" means diapers, training pants, absorbent underwear, incontinence products for adults, and products for women's hygiene.

As used herein, the term "protective cover" means a cover for vehicles such as cars, trucks, airplanes, motorcycles, bicycles, golf carts, etc. , covers for equipment frequently left outdoors such as grills, garden and yard equipment (mowers), rotary cultivators, etc.) and meadow furniture, as well as floor coverings, table cloths and covers for lunch area.

As used herein, the term "outer fabric" means a fabric which is primarily, but not exclusively, used in the open. The outer fabric includes a fabric used in protective covers, a tow / tent fabric, tarpaulins, awnings, canopies, tents, agricultural fabrics and outdoor clothing, pants, shirts, jackets, gloves, socks, shoe covers , and similar.

TEST METHODS Cup crush: The fall of a non-woven fabric can be measured according to the "cup crush" test. The cup crush test evaluates fabric stiffness by measuring the peak load required so that a hemispherically formed foot 4.5 cm in diameter deforms a 23 cm by 23 cm piece of cloth in an inverted cylinder of approximately 6.5 cm in diameter. 6.5 cm in height while the cup-shaped fabric is surrounded by a cylinder of approximately 6.5 cm in diameter to maintain a uniform deformation of the cup-shaped fabric. The foot and cylinder are aligned to avoid contact between the walls of the cup and the foot that could affect the peak load. The peak load was measured while the foot was lowered at a rate of about 38.1 cm per minute (0.25 inches per second). A lower cup crush value indicates a softer tissue. One suitable device for measuring cup crushing is the FTD-G-500 load cell (range 500 grams) available from Shaevitz Company, of Pennsauken, NJ. Cup crushing was measured in grams.

Tension: The tensile strength of a fabric can be measured according to the ASTM D-1682-64 test. This test measures the resistance in kilograms (pounds) and the elongation in percent of a fabric.

Spunbond fibers are small diameter fibers which are formed by extruding a melted thermoplastic material as filaments from a plurality of usually circular and thin capillaries of a spinning organ with the diameter of the extruded filaments then being rapidly reduced. Spunbond fibers are generally continuous and have diameters greater than 7 μm, more particularly between about 10 and 30 μm. The fibers are usually deposited on a band or foraminous forming wire where they form a fabric.

Spunbonded fabrics are generally slightly bonded in some way immediately after they are produced in order to give them sufficient structural integrity to withstand the rigors of further processing to a finished product. This attachment of a first light step can be achieved through the use of an adhesive supplied to the fibers as a liquid or powder which can be activated by heat, or more commonly, by the compaction rollers.

The fabric then generally moves to a more substantial second step joining process where it can be joined with other non-woven fabrics which can be spunbond fabrics, formed by melted or bonded-carded blown, films, woven fabrics , foams, etc. The second step junction can be achieved in various forms such as hydroentanglement, perforation, ultrasonic bonding, air bonding, adhesive bonding and thermal point or calendering bonding.

Compaction rollers are widely used for the first light-weight joint and have a number of disadvantages which are delineated above. For example, closures caused by the wrapping of the non-woven fabric are very expensive. These "compaction shells" require the dismantling and cleaning of the compaction rollers which takes a substantial amount of time and effort. This is costly not only from the point of view of loss or discarded material, but also from the loss of production, assuming one is operating at full capacity. The compaction rollers can also force a fall of the polymer from a forming imperfection is the foraminous band or the forming wire on which the spunbonded fabrics are formed. This "milling" of the polymer drop can ruin a band for additional use, requiring its replacement. Since the forming wires are very long and of specialized materials, the replacement costs can be as high as $ 50,000 dollars, as of the date this is written, in addition to the lost production while changing the band.

The novel method for providing integrity to a non-woven fabric that is the subject of this invention, avoids the use of rollers and compaction adhesives. This invention works through the use of a "hot air knife" or HAK. A hot air knife is a device which focuses a stream of heated air at a very high flow rate, generally from about 305 to 3050 meters per minute (1000 to about 10000 feet per minute (fpm)), directed to the non-woven fabric immediately after its formation.

The air from the hot air blade is heated to an insufficient temperature to melt the polymer in the fiber but enough to soften it slightly. This temperature is generally between about 93 and 290 ° C (200 and 550 ° F) for the thermoplastic polymers commonly used in spinning.

The focused air stream HAK is arranged and directed by at least one slot of about 3 to . 4 mm (1/8 to 1 inch) wide, particularly around 9.4 mm (3/8 inch), serving as the outlet for heated air towards the fabric, with the groove running in a direction essentially transverse to the machine about essentially the full width of the fabric. In other embodiments, there may be a plurality of grooves arranged close to each other or separated by a slight gap. The at least one slot is preferably, although not essentially, continuous and may be composed of closely spaced holes for example.

The HAK has a plenum to distribute and contain the heated air before leaving the slot. The full pressure of the HAK is preferred between about 0.2 kPa and 3 kPa (1.0 and 12.0 inches of water, 2 to 22 mmHg), and the HAK is placed between about 6 mm and 254 mm (0.25 and 10 inches) ) and more preferably 19 to 76.2 mm (0.75 to 3.0 inches) above the forming wire. In a particular embodiment, the full HAK size, as shown in Figure 2, is at least twice the area of the cross section for the CD flow relative to the total output slot area.

Since the foraminous wire upon which the polymer is formed generally moves at a high velocity rate, the time of exposure of any part of the tissue to the area discharged from the hot air blade is less than one tenth of a second. and generally about one hundredth of a second in contrast to the continuous air union process which has a much longer residence time. The HAK process has a greater range of variability and control of at least air temperature, air velocity and distance from the full HAK to the tissue.

As mentioned above, the spinning process uses thermoplastic polymers which may be known to those skilled in the art. Such polymers include polyolefins, polyesters, polyether esters, polyurethanes and polyamides, and mixtures thereof, more particularly polyolefins such as polyethylene, polypropylene, polybutene, ethylene copolymers, propylene copolymers and butene copolymers. Polypropylenes that have been found useful include, for example, the polypropylene available from Himont Corporation of ilmington, Delaware, under the trade designation PF-304, the polypropylene available from Exxon Chemical Company of Baytown, Texas, under the trade designation Exxon 3445 and the polypropylene available from Shell Chemical Company of Houston, Texas, under the trade designation DX 5A09.

Although the present invention can use air temperatures above the melting point of the polymer, the surface of the polymer does not reach its melting point by controlling the air flow rate and maintaining the exposure of the fabric within the specified time range.

Referring to the drawings, particularly Fig. 1, an exemplary process for providing integrity to a spunbond fabric without the use of compaction adhesives or rollers is illustrated schematically in step 20.

The polymer is added to the hopper 1 from which it is fed into the extruder 2. The extruder 2 heats the polymer and melts it and forces it into the spinner 3. The spinner 3 has the openings arranged in one or more rows . The openings of the spinning organ 3 form a curtain of filaments that extend downwards when the polymer is extruded. The air from the cooling blower 4 cools the filaments extending from the spinning organ 3. A fiber pulling unit 5 is placed below the spinner 3 and receives the cooled filaments.

Illustrative fiber pulling units are shown in U.S. Patent Nos. 3,802,817, 3,692,618 and 3,423,266. The fiber pull unit pulls the filaments or fibers by sucking the air that enters from the sides of the duct and flows down through the duct.

A generally foraminous endless forming surface 6 receives the continuous spunbonded fibers from the fiber pulling unit 5. The forming surface 6 is a band which travels around the guide rollers 7. A vacuum 8 placed below the forming surface 6 pulls the fibers against the forming surface 6. Immediately after forming, hot air is directed through the fibers from a hot air knife (HAK) 9. The hot air knife 9 gives the woven sufficient integrity to be passed out of the forming surface and up to the band 10 for further processing.

Figure 2 shows the cross-sectional view of an exemplary hot air knife. The area of the plenum 1 is at least twice the cross-sectional area for the flow in the direction transverse to the machine in relation to the air outlet area of total slot 2.

Figures 3 and 4 show the electron analysis micrograph (SEM) photos which have been treated with the HAK. The fabric of figure 4 has been treated at slightly more severe conditions than those of figure 3. Note that there is very little union between the filaments in figure 3 and a little more in figure 4. figure 3 is an increase of 119X and Figure 4 is an increase of 104X. The fabrics subjected to only the compaction rollers did not have these characteristic bonds.

The fabric used in the process of this invention may be a single-ply form or a multiple-ply laminate of spunbond and other fibers but is not necessarily limited to spunbond. Such fabrics usually have a basis weight of from about 5 to about 407 grams per square meter (0.15 to 12 ounces per square yard). Such a multilayer laminate may be a mode wherein some of the layers are spun bonded and some are formed by meltblowing such as a meltblown / spunbond (SMS) spin-bonded laminate as described in the patent. No. 4,041,203 issued to Brock et al., and in United States Patent No. 5,169,706 issued to Collier et al., or as a spunbonded / spunbonded laminate. Note that there may be more than one layer of meltblown present in the laminate.

An SMS laminate can be made by depositing in sequence on the mobile conveyor belt or the forming wire first a layer of spunbond fabric, then at least one layer of meltblown fabric and at the last another layer of spunbond, Treat the fabric with the HAK after depositing each layer by spun bonding. The treatment of the meltblowing layers with the hot air blade is not thought to be necessary since the meltblown fibers are usually sticky when they are deposited and therefore adhere naturally to the picking surface but such treatment with the hot air knife it is not excluded, which in the case of an SMS laminate is a layer joined by spinning. Alternatively, the fabric layers can be individually made, collected in rolls, and combined in a separate joining step, with each layer joined by spinning having been subjected to the hot air blade as it is produced.

The most substantial secondary binding step is generally achieved by the previously mentioned methods. One such method is calendering and several patterns of calendering rolls have been developed. An example is the expanded Hansen Pennings pattern with around a 15% bond area with about 100 joints / 6.45 cm2 (100 joints / square inches) as taught in United States Patent No. 3,855,046 issued to Hansen and Pennings. Another common pattern is a diamond pattern with slightly off-centered and repetitive diamonds.

The fabric of this invention can also be laminated with films, glass fibers, short fibers, paper and other commonly used materials known to those skilled in the art.

CONTROL 1 The non-woven spunbonded fabrics were generally made according to Figure 1 in which the layer was deposited on a mobile forming wire. Five samples were made with an average basis weight of 42 grams per square meter (1.24 ounces per square yard). The polymer used to produce the layer was Exxon 3445 polypropylene to which 2% by weight of titanium dioxide (Ti02) was added to provide a white color to the fabric. The Ti02 used was designated SCC4837 and is available from Standridge Color Corporation of Social Circle, Georgia. The fabric was processed through the compaction rollers after forming and a hot air knife was not used.

CONTROL 2 The non-woven spunbonded fabrics were generally made according to Figure 1 in which the layer was deposited on a mobile forming wire, except that the fabric was processed through the compaction rollers after forming and was not used. a hot air blade. Five samples were made with an average of 20 grams per square meter (0.6 ounces per square yard) of base weight. The polymer and the additive were the same as in Control 1.

CONTROL 3 The non-woven spunbonded fabrics were generally made according to Figure 1 in which the layer was deposited on a mobile forming wire, except that the fabric was processed through the compaction rollers after forming and was not used. a hot air blade. Five samples were made with an average of 17 grams per square meter (0.5 ounces per square yard) of base weight. The polymer and the additive were the same as in Control 1.

EXAMPLE 1 The non-woven spunbonded fabrics were generally made according to Figure 1 in which the layer was deposited on a mobile forming wire. Five samples were made with an average of 42 grams per square meter (1.25 ounces per square yard) of base weight. The polymer used to produce the Exxon 3445 polypropylene layer to which 2% by weight of titanium dioxide (Ti02) was added to produce a white color to the fabric. The Ti02 used was designated SCC4837 and is available from Standrige Color Corporation of Social Circle, Georgia. The fabric was not processed through the compaction rolls after forming but was treated with a hot air knife. The hot air blade was placed 2.54 cm (1 inch) above the fabric and the slot of the hot air blade was 0.635 cm (one quarter of an inch) wide. The hot air blade had a full pressure of 1.7 kPa (7 inches of water, 13 mmHg) and a temperature of 160 ° C (320 ° F). The exposure time of the fabric to the air of the hot air blade was less than one tenth of a second.

EXAMPLE 2 Unwoven fabrics joined by spinning generally were made according to Figure 1 in which the layer was deposited on a mobile forming wire. Five samples were made with an average base weight of 20 grams per square meter (0.6 ounces per square yard). The polymer and the additive were the same as in Example 1. The fabric was not processed through the compaction rollers after forming but was treated with a hot air knife. The hot air blade was placed 2.54 cm (1 inch) above the fabric and the HAK slot was 0.635 cm (one quarter of an inch) wide. The hot air blade had a full pressure of 1.7 kPa (7 inches of water, 13 mmHg) and a temperature of 160 ° C (320 ° F). The exposure time of the fabric to the air of the hot air blade was less than one tenth of a second.

EXAMPLE 3 The nonwoven spunbond fabrics were made generally according to Figure 1 in which the layer was deposited on a mobile forming wire. Five samples were made with an average of 17 grams per square meter (0.5 ounces per square yard) of base weight. The polymer and the additive were the same as in Control 1. The fabric was not processed through the compaction rollers after the formation but instead was treated with a hot air knife. The hot air blade was placed 2.54 cm (1 inch) above the fabric in the groove of the hot air blade was 0.635 cm (one quarter of an inch) wide. The hot air blade had a full pressure of 1.7 kPa (7 inches of water, 13 mmHg), and a temperature of 166 ° C (330 ° F). The exposure time of the fabric to the air of the hot air blade was less than one tenth of a second.

The average results of the test of five tissues of each control and example are shown in Table 1. The line speed is given in one m per minute (foot per minute), the full pressure in kPa (inches of water) and the temperature in ° C (° F).

TABLE 1 Controls Examples gsm (OSY) 42 (1.24) 21 (.62) 17.3 (0.51) 42.4 (1.25) 21. (0.62) 17 (0.5) kg tension MD (pounds) 11.16 (24.6) 5.17 (11.4) 3.9 (8.6) 10.39 (22.9) 5.08 (11.2) 3.95 (8.7) kg tension CD (pounds) 9.34 (20.6) 3.72 (8.2) 3.31 (7.3) 8.53 (18.8) 4.17 (9.2) 2.8 (6.2) Crushing of Cup g 162.6 39.8 27.4 172.6 43.8 29.4 Crushing energy gm mm 3062 776 423 3416 733 517 Line Speed m / min (foot / min) 56.1 (184) 114 (374) 141 (464) 56.1 (184) 114 (374) 141 (464) Pres Plan, mmHg (inches of water) NA NA NA 1.7 (7) 1.7 (7) 1.7 (7) Temperature ° C (° F) NA NA NA 160 (320) 160 (320) 166 (330) It can be seen from the preceding examples that a hot air knife can achieve comparable tissue integrity results if not higher than those of the compaction rollers without the tremendous and costly problems that have been experienced with those devices and without negatively impacting them. the key tissue properties such as resistance or fall.

Claims (25)

R E I V I N D I C A C I O N S

1. A method for producing a non-woven fabric comprising the steps of: forming a non-woven fabric by passing the fabric through a hot air blade having at least one groove to slightly bind the fibers of the fabric in order to provide sufficient integrity to the fabric for further processing.

2. The method as claimed in clause 1, characterized in that the non-woven fabric is a woven fabric by spinning or a fabric formed by melt blowing.

3. The method as claimed in at least one of clauses 1 or 2, characterized in that the fabric is formed of a fiber selected from the group consisting of monocomponent and biconstituent fibers.

4. The method as claimed in at least one of clauses 1 to 3, characterized in that said hot air blade operates at a temperature between about 93 and 290 ° C (200 and 550 ° F).

5. The method as claimed in at least one of clauses 1 to 4, characterized in that said hot air blade operates at an air flow of between 305 and 3050 meters per minute (1000 and 10000 feet per minute).

6. The method as claimed in at least one of clauses 1 to 5, characterized in that said fabric is essentially free of adhesives before said passing step.

7. The method as claimed in at least one of clauses 1 to 6, characterized in that said fabric is not subjected to the compaction rollers.

8. The method as claimed in at least clauses 1 to 7, characterized in that said fabric is subjected to said hot air blade for less than one-tenth of a second.

9. The method as claimed in at least one of clauses 1 to 8, characterized in that said hot air blade has a plenum and said plenum has an area which is at least twice the area in the cross section for the CD flow in relation to the total output slot area.

10. The method as claimed in at least one of clauses 1 to 9, characterized in that said fabric is composed of microfibers of a polymer selected from the group consisting of polyolefins, polyamides, polyetheresters, polyesters and / or polyurethanes.

11. The method as claimed in clause 10, characterized in that said polymer is a polyolefin.

12. The method as claimed in clause 11, characterized in that said polyolefin is polypropylene.

13. The method as claimed in clause 11, characterized in that said polyolefin is polyethylene.

14. The method as claimed in at least one of the preceding clauses, characterized in that it comprises the step of depositing on the fabric at least one layer of melted or spunbonded blowing.

15. The method as claimed in clause 14, characterized in that it comprises the step of depositing on the fabric and on said at least one layer of blowing melted or joined by spinning, a second layer joined by spinning or melt blowing adjacent to the meltblown layers bonded by spinning to form a laminate and pass said laminate through said hot air blade.

16. The method as claimed in clauses 14 or 15, further characterized in that it comprises the step of joining the laminate thermal point.

17. The use of a fabric as claimed in at least one of the preceding clauses in an article selected from the group consisting of medical products, personal care products and outdoor fabrics.

18. The use as claimed in the clause 17, characterized in that said article is an article for personal care and said article for personal care is a diaper.

19. The use as claimed in the clause 17, characterized in that said article is an article for personal care and said article for personal care is a training brief.

20. The use as claimed in the clause 17, characterized in that said article is an article for personal care and said item for personal care are absorbent underpants.

21. The use as claimed in clause 17, characterized in that said article is an article for personal care and said article for personal care is an incontinence product for adults.

22. The use as claimed in clause 17, characterized in that said article is an article for personal care and said article for personal care is a product for the hygiene of women.

23. The use as claimed in clause 17, characterized in that said article is a medical product and said medical product is a surgical gown.

24. The use as claimed in clause 17, characterized in that said article is a medical product and said medical product is a sterilization wrap.

25. The use as claimed in clause 17, characterized in that said article is a fabric for the exterior, and said fabric for the exterior is a protective cover. SUMMARY A process is provided which comprises the step of subjecting a newly produced spunbond fabric to a heated flow of high air flow rate through essentially the width of the fabric to join the fibers of the fabric together very slightly. Such a union must be the minimum necessary in order to satisfy the needs of an additional processing but not to detrimentally affect the tissue. The fibers of the fabric may be monocomponent or biconstituent and the fabric must be substantially free of adhesives and not subjected to compaction rollers.