EP0389612A1

EP0389612A1 - Hydraulically entangled wet laid base sheets for wipers.

Info

Publication number: EP0389612A1
Application number: EP89911338A
Authority: EP
Inventors: Hugo P Watts; Sharon L Watkins; Cherie H Everhart; Wielen Michael J Vander
Original assignee: Kimberly Clark Corp
Current assignee: Kimberly Clark Worldwide Inc
Priority date: 1988-10-05
Filing date: 1989-09-29
Publication date: 1990-10-03
Anticipated expiration: 2009-09-29
Also published as: WO1990004066A2; GR890100639A; WO1990004066A3; AU624191B2; JP2838110B2; PT91915A; JPH03504622A; ES2016739A6; CA1318115C; KR0157409B1; ZA897322B; EP0389612B1; IE71223B1; DK137090D0; PT91915B; MX170986B; ATE107719T1; DE68916415T2; AU4402889A; DE68916415D1

Abstract

A cloth-like nonwoven material useful for wiping and having strength, toughness, abrasion resistance and resistance to certain solvents and/or chemicals is made from mixtures of wood pulp and staple fibers randomly distributed and hydraulically entangled with each other to form a coherent entangled fibrous structure having a thickness index of at least about 0.008 and a ratio of machine direction strength to cross machine direction strength of at least about 1.5.

Description

HYDRAULICA Y ENTANGLED WET LAID BASE SHEETS FOR WIPERS

FIELD OF THE INVENTION

The field of the present invention includes nonwoven composite materials, for example hydroentangled materials containing mixtures of wood pulp fibers and staple fibers, which may be used as wipers for industrial and other applications.

BACKGROUND OF THE INVENTION

Nonwoven materials such' as, for example, meltblown or spunbonded polypropylene may be used as wipers. In certain applications such as automobile finishing the wiper is usually moistened with one or more volatile or semi-volatile solvents such as, for example, isopropyl alcohol/water, n-heptane, naphtha, and C₅ to C7 aliphatic hydrocarbons in order to remove grease, fingerprints and/or smudges from the automobile finish before painting or priming. Some solvents and/or other chemicals cause some components such as, for example, low molecular, weight polyolefins to leach out onto the wiped surface rendering that surface unsuitable for painting. Many nonwoven materials are hydrophobic and require treatment with one or more surfactants to become wettable. The surfactant may also be transferred to the wiped* surface rendering that surface unsuitable for painting or priming.

Some nonwoven materials have a low tendency to shed fibers and may be used as wipers in applications where lint and dust are undesirable such as, for example, micro-electronic manufacturing clean rooms. However, such wipes are typically treated with surfactants to provide the absorbance and clean wiping characteristics desired in such applications. Surfactant treatments typically comprise an anionic surfactant such as, for example sodium dioctyl sulfosuccinate which has a high metallic ion content. These metallic ions provide special problems since, if present in sufficient concentrations, they may adversely affect the electrical properties of metal oxide semiconductors. Additionally, certain nonwoven materials have a slow rate of electrical charge dissipation which results in static build-up. Static build-up on a wiper may cause problems such as, for example, discomfort for the user, hazards with flammable solvents or damage to sensitive electronic equipment.

Nonwoven materials used in wiping applications typically require some bonding to maintain the integrity of the nonwoven web. Thermal bonding can reduce the content of "active" fibers available for absorption. Thermal bonding also results in a stiffer material which may scratch or abrade a soft surface such as newly applied paint. Chemical bonding offers potential problems with extractable bonding agents.

Nonwoven materials such as, for example, bonded carded webs and air laid webs can be hydroentangled into a coherent web structure and used as wipers. However, these materials typically have high strength in only one direction because the fibers in the web are oriented in only one direction during the initial web forming process. That is, the materials have high strength in one direction such as, for example, the machine direction and relatively low strength in the cross machine direction. This inequality of strength is undesirable because the material is more likely to tear in the weak direction and because the material must be much stronger than necessary in one direction in 5 order to meet minimum strength requirements in the weak direction.

Composite hydroentangled materials containing staple fibers and wood pulp fibers are typicaliy made by overlaying a wood pulp Q tissue layer on a staple fiber web and hydraulically entangling the two layers. Each side of the resulting hydroentangled material usually has a noticeably different level of abrasion resistance from the other side because of the way the material is produced. 5 Wood pulp and combinations of wood pulp and staple fibers can b processed to make paper tissue and paper items which may be use as wipers. Although these wipers have desirable absorbency economy, and resistance to certain solvents and chemicals, the generally have low strength (particularly when wet) , lo toughness, low abrasion resistance and undesirable levels o lint. Such wipers also have poor visual and tactile aesthetics For example, these materials are typically thin and sheet-lik having a thickness index of about 0.01 or typically less tha 0.01. Some physical properties of^' these materials such as, fo example, strength and abrasion resistance may be improved b adding binders. However, binders increase the cost of the wipe and may leave residue on the surface to be wiped.

wipers may also be formed from woven materials. Depending on th material used, the wipers may have desirable absorbency an strength but typically are expensive and must be reused in orde to be economical. Reusable cloths are not desirable because the may retain foreign, possibly injurious objects from previo uses. Cloth made from natural fibers has the disadvantage tha many natural fibers such as, for example, cotton have natur oils such as, for example, cotton oil that can be extracted some solvents and deposited onto the wiped surface. Cloth ma from man-made fibers such as, for example, polyester may not able to absorb water unless the fibers are treated with surfactant so that the fibers are wettable. The .presence surfactants is undesirable for the reasons noted above.

DEFINITIONS The term "Peak Load" as used herein is defined as the maxim amount of load or force encountered in elongating a material break. Peak Load is expressed in units of force, i.e., gf. *τ

The term "Peak Energy Absorbed" (Peak EA) as used herein defined as the area under a load versus elongation (stress vers strain) curve up to the point of "peak" or maximum load. Peak is expressed in units of work, i.e., kg-mm.

The term "Total Energy Absorbed" (TEA) as used herein is defin as the total area under a load versus elongation (stress vers strain) curve up to the point where the material breaks. TEA expressed in units of work, i.e., kg-mm.

The term "Peak Percentage Elongation" as used herein is defin as relative increase in length of a specimen when a material extended to up to the point of "peak" or maximum load. Pe percentage elongation is expressed as a percentage of t original length of the material, i.e., [(increase length)/(original length)] X 100.

The term "Total Percentage Elongation" as used herein is defi as the relative increase in length of a specimen when a materi is extended to up to the point where the material breaks. To percentage elongation is expressed as a percentage of original length of the material, i.e., [(increase length)/(original length)] X 100.

The term "Thickness Index" as used herein is defined as value represented by the ratio of the thickness and the ba weight of a material where the thickness is described millimeters (mm) and the basis weight is described in grams square-, meter (gsm) . For example, the thickness index may expressed as follows: Thickness Index - [thickness(mm)/basis weight(gsm)]

The term "machine direction" as used herein is defined as direction of travel of the forming surface onto which fibers deposited during formation of composite nonwoven material. The term "cross-machine direction" as used herein is defined a the direction which is perpendicular to the machine direction.

The term "Isotropic Strength Index" as used herein is defined a the value represented by the ratio of the peak load of material in one direction such as, for example, the machin direction with the peak load of the material in the perpendicula direction, for example, the cross-machine direction. The inde is typically expressed as the ratio of the machine direction pea load with the cross-machine direction peak load. Material usually have an index of greater than one (1) unless comparison of peak load in a particular direction is specified An isotropic strength index near one (1) indicates an isotropi material. An isotropic strength index significantly greater tha one (1) indicates an anisotropic material.

The term "staple fiber" as used herein refers to natural o synthetic fibers having an approximate average length of fro about 1 mm to about 24 mm, for example, from about 6 mm to abou 15 mm, and an approximate denier of about 0.5 to about 3, fo example, from about 0.7 to about 1.5 denier.

The term "Total Absorptive Capacity" as used herein refers to t capacity of a material to absorb liquid and is related to t total amount of liquid held by a material at saturation. Tot Absorptive Capacity is determined by measuring the increase the* weight of a material sample resulting from the absorption a liquid and is expressed, in percent, as the weight of liqu absorbed divided by the weight of the sample. That is, Tot Absorptive Capacity _* [(saturated sample weight - samp weight)/sample weight] X 100. The term "Mop Up Capacity" as used herein refers to the capacit of a material to absorb liquid after the material has bee saturated and wrung to simulate the multiple use of a wiper The mop up capacity is related to the amount of liquid remainin in a material after liquid is removed from a saturated materia by wringing. Mop up capacity is determined by measuring th difference between the saturated weight and the wrung out weigh of a material sample and dividing that amount by the weight o the dry sample. It is expressed, in percent, as the weight o liquid removed from the sample by wringing divided by the weigh of the dry sample. That is, [(saturated sample weight - wrun out sample weight)/weight of dry sample] X 100.

SUMMARY OF THE INVENTION

The present invention addresses the above-discussed problems b providing cloth-like nonwoven materials made from mixtures wood pulp fibers and staple fibers randomly distributed a hydraulically entangled with each other to form a cohere entangled fibrous structure having a thickness index of at lea about 0.00S and a isotropic strength index of not greater th about 1.5.

The materials of the present invention are made in a two st process. The materials are formed by conventional wet-formi techniques using an inclined wire. The materials are th hydroentangled using conventional hydroentangling techniques pressures ranging from about 500 to about 2000 pounds per squa inch (psi) and at speeds ranging from about 20. to about 3 meters per minute to form a coherent web structure without t use of thermal or chemical bonding.

The wet-formed materials of the present invention conta randomly distributed mixtures of wood pulp fibers and stap fibers. Typical materials contain from about 50 to about percent by weight staple fiber and from about 10 to about percent by weight wood pulp fibers. Materials may contain up to ■ about 100 percent staple fibers. The cloth-like nonwoven materials of the present invention have basis weights from about 30 to about 150 gsm.

staple fibers used in the invention may have a denier in the range of about 0.7 to about 3 and an average length in the range of about 5 mm to about 18 mm. The staple fibers may be one or more of rayon, cotton, polyester, polyamides and polyolefins such as, for example, one or more of polyethylene, polypropylene, polybutene, ethylene copolymers, propylene copolymers and butene copolymers. Long fiber wood pulps such as hardwood pulps ar also particularly useful. Mixtures of long fiber and short fibe wood pulps may also be used.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention there is provided a cloth-like composite nonwoven material having strength toughness, abrasion resistance, resistance to certain solvents and good visual and tactile aesthetics.

The cloth-like nonwoven material is made from a dispersion o wood pulp fibers and staple fibers which is formed into a laye of randomly distributed fibers on a foraminous surface b conventional wet-laying techniques using an inclined wire Exemplary wet-forming processes are described in, for example U.S. Patent No. 2,414,833 to Osborne, the disclosure which i hereby incorporated by reference.

In the headbox of the wet-forming apparatus, the dispersion o fibers may be dilute, for example, containing about 2.5 grams o dry fiber per liter of fiber and water mixture. The consistenc of the uniform layer of fibers after formation on the foraminou surface may range from about 10 to about 30 weight percent fibe solids in water. For example, the consistency may be about 2 percent by weight solids. The uniform layer of fibers may transferred to a different surface for entangling. T entangling surface may be, for example, a wire screen of fr about 35 to about 100 mesh. The entangled material may transferred to another surface for patterning. Mesh size and/ the texture of the foraminous patterning surface can be varied create different visual and tactile properties. A coarse me such as, for example, from about 14 to about 35 mesh can be us to impart a textile or cloth-like appearance and feel.

The newly formed layer of randomly distributed fibers hydraulically entangled to form a nonwoven material. Exempla hydraulic entangling processes are described in, for exampl U.S. Patent No. 3,485,706 to Evans, the disclosure of which hereby incorporated by reference. For example, entangling may effected with a manifold produced by Honeycomb System Incorporated containing a strip having 0.005 inch diamet orifices, 40 holes per inch and 1 row of holes. Other manifo configurations may also be used. The wet-formed materials may run under the strip at speeds ranging from about 20 to about 3 meters per minute to be entangled by jets of liquid at pressur ranging from about 500 to about 2000 psi. It has been found th greater strength materials have been obtained by hydroentangli the base sheets at slower speeds and/or higher pressure Additional passes through the hydroentangling equipment al yields improved strength.

Patterning may be accomplished by transferring the entangl material to a coarse mesh such as, for example, 14 to about mesh and running the material under the hydraulic entangli apparatus at pressures from about 200 to about 1000 psi.

The nonwoven material formed by hydraulic entangling may dried utilizing one or more conventional drying methods such a for example, forced air, vacuum, heat or pressure. The nonwov material may be dried on a foraminous surface such as, for example, a wire mesh. Alternatively, the nonwoven material may be dried on an un-textured surface by conventional drying methods. Materials- dried on a foraminous surface are softer and more drapeable than materials dried on an un-textured surface. 5 Additionally, materials dried on a foraminous surface can be expected to have lower peak loads but greater peak elongations than materials dried on an un-textured surface.

In connection with this description certain test procedures hav 0 been employed to determine oil and water absorption capacity an rate, linting, abrasion resistance, static decay, drap stiffness, sodium ion concentration, level of extractables, pea load, peak energy absorbed, total energy absorbed, pea elongation, and total elongation. 5

Lint tests were carried out using a Climet™ particle counte model Cl-250 available from the Climet Instrument Company Redlands, California. Test were conducted essentially i accordance with INDA Standard Test 160.0 - 83 with the followin 0 changes: (1) the sample size was 6 inches X 6 inches; and (2) th background count was not determined for each individual specime tested. This test employed a mechanical particle generator whic applied bending, twisting and crushing forces to sampl specimens. Samples were placed in machine direction alignment i 5 an enclosure and twisted through an angle of 150* for a distanc of .4.2 inches at a rate of about 70 cycles per minute. Th enclosure is connected by tubing to the particle counter whic draws the particles to the counter at a rate of about 20 cubi feet per hour. The flow rate through the instrument sensor i

30 1.0 cubic feet per hour. Each count takes 36 seconds an represents the number of particles of the specified size in 0.0 cubic feet of air.

35 Grab Tensile Test were conducted essentially in accordance wi Method 5100 of Federal Test Method Standard No. 191A, utilizi samples of the entangled material having a width of about inches and a length of about 6 inches. The samples were held opposite ends by a one (1) square inch gripping surface. T samples were tested with an Intellect II Model tensile testi apparatus available from Thwing Albert and with an Instron Mod 1122 Universal Testing Instrument, each having a 3 inch jaw sp and a crosshead speed of about 12 inches per minute. Values f peak load, peak energy absorbed, peak percentage elongatio total energy absorbed and total percentage elongation we determined.

The rate of electrical charge dissipation of the material w determined essentially in accordance with Method 4046 of Feder Test Method Standard No. 101B. Test results were obtained wi an Electro/Tech™ Calibrated Electrostatic Charge Detector wi High Voltage Sample Holder using rectangular samples measuring 1/2 inches X 3-1/2 inches.

The rate that the material absorbed oil was determined follows: A sample measuring 300 mm in the cross-machi direction and about 150 mm in the machine direction was plac flat on the liquid surface of an oil bath containing SAE 20 / motor oil. A stopwatch was used to record the time for t sample to completely wet-out, that is, total saturation of percent of the surface area of the sample. Non absorbent strea of the material are not acceptable under the definition complete wet-out but non absorbent individual fibers a acceptable. The rate that the material absorbed water w determined by the same procedures utilized for oil except th distilled water was used instead of oil.

The capacity of the material to absorb oil was determined follows: A dry 15 cm X 30 cm standard felt available from t British Paper and Board Industry Federation, London, England was submerged for at least 24 hours in an oil bath containing SAE 20W/50 motor oil. The weight of a 10 cm X 10 cm material sample was determined to the nearest 0.01 gram. The sample was then submerged in the oil bath over the piece of felt until the sample was completely saturated (at least 1 minute) . The felt and sample were removed and suspended over the bath until the observed drainage of oil from the sample was complete, i.e., when the sample assumed a single overall color or appearance. The drained sample was weighed to the nearest 0.01 gram and the total absorptive capacity was calculated.

The mop up capacity of the material was determined from the sample in the total absorptive capacity test by folding the saturated sample in half, and then in half again. The sample was then grasped between the thumb and fore finger on opposite edges and twisted as far as possible to wring oil from the sample. The oil was allowed to drain while the sample was twisted. When no further oil drained from the twisted sample the sample wa untwisted. The sample was weighed to the nearest 0.01 gram an the mop up capacity was determined.

The capacity of the material to absorb and mop up water wa determined by the same procedures utilized for oil except tha distilled water was used instead of oil.

The drape stiffness measurements were performed using a Shirle Stiffness Tester available from Shirley Developments Limited, Manchester, England. Test results were obtained essentially i accordance with ASTM Standard Test D 1388 except that the sampl size was 1 inch X 8 inches with the larger dimension in th direction being tested.

The levels of (1) extractables in isopropyl alcohol, 1,1,1 trichloroethane and distilled water and (2) the concentration o sodium ions was determined by the following procedure. Duplica samples of the wipes weighing approximately 2 grams were reflux for 4 hours in 200 mL of solvent using a soxhlet extracti apparatus. The solvent was evaporated to dryness and t percent extractables was calculated by determining t difference in the weight of the container before and aft evaporation. The percent extractables is expressed as weig percent of the starting material. The quantity of sodium in t sample was determined by measuring the concentration of sodi ions in water obtained from the soxhlet extraction apparat after the water extractables test. A Perkin-Elmer Model 3 atomic absorption spectrophotometer was used to measure t sodium ion concentration in the water.

The abrasion resistance of the material was determin essentially in accordance with British Standard Test Method 5.69 1979 with the following changes: (1) the abrasion machine us was available under the trade designation Martindale Wear a Abrasion Tester Model No. 103 from Ahiba-Mathis, Charlotte, Nor Carolina; (2) the samples were subjected to 100 abrasion cycl under a pressure of 1.3 pounds per square inch (psi) or kilopascals (kPa) ; (3) a 1.5 inch diameter abradant was a c from a 36 inch X 4 inch X 0.050 (±0.005) inch piece of gla fiber reinforced silicone rubber having a surface hardness of 8 Durometer, 81±9 Shore A available from Flight Insulati incorporated. Marietta, Georgia, distributors for Connecti Hard Rubber; and (4) the samples were examined for the presen of surface fuzzing (fiber lofting), pilling, roping, or hole The samples were compared to a visual scale and assigned a we number from 1 to 5 with 1 indicating little or no visib abrasion and 5 indicating a hole worn through the sample.

EXAMPLE 1 A mixture of about 50 percent by weight hardwood pulp availa from the Weyerhauser Company under the trade designation Gr Regular and about 50 percent by weight uncrimped polyester staple fiber (1.5 denier x 12 mm), was dispersed to a consistency of about 0.5 percent by weight solids an then formed into handsheets of about 75 gsm on a standard 94 x 100 mesh plastic screen.

A manifold available from Honeycomb Systems, Incorporated was utilized to entangle the handsheets. The handsheets were transferred to a standard 100 x 92 mesh stainless steel wire. The manifold was positioned approximately one-half (1/2) inch above the stainless steel wire mesh. The manifold contained a strip having 0.005 inch diameter orifices, 40 holes per inch and 1 row of holes. The strip was inserted into the manifold with the conical shaped holes diverging in the direction of the wire. Entanglement was performed with the handsheet travelling at a speed of about 20 meters per minute.

The handsheets were entangled at pressures of 200, 400, 600, 800, 1200 and 1400 psi on one side of the sheet and at pressures of 1200 and 1400 psi on the opposite side of the sheet. The flow rate of the entangling water was 1.054 cubic meters per hour per inch of strip. The entangled sheets were air dried at ambient temperature. The dried material had a basis weight of about 7Q gsm.

Samples of the entangled material having a width of about 4 inches were tested using an Intellect II tensile testing apparatus available from Thwing Albert and an Instron Model 1122 Universal Testing Instrument, each having a 3 inch jaw span and a crosshead speed of about 12 inches per minute. Values for Peak Load, Peak EA, Peak Percentage Elongation, TEA and Total Percentage Elongation for the dry samples are reported in Table 1 for the machine direction and the cross-machine direction. Similar data was collected for wet samples in the -machine direction only and is also reported in Table 1. EXAMPLE 2 A mixture of about 20 percent by weight hardwood pulp availa from the Weyerhauser Company under the trade designation Gr Regular, about 40 percent by weight uncrimped polyester sta fiber (1.5 denier x 12 mm) and about 40 percent by wei uncrimped rayon staple fiber (1.5 denier x 12 mm) was dispers and then formed into handsheets of about 75 gsm on a standard x 100 mesh plastic screen.

The handsheet was entangled using the equipment and procedure Example 1 on a standard 100 x 92 mesh stainless steel wire pressures of 600, 900, 1200 and 1500 psi on one side of the sh and at pressures of 1200 and 1500 psi on the opposite side of sheet. The flow rate of the entangling water was 0.808 cu meters per hour per inch of strip. The entangled sheets were dried at ambient temperature. The dried material had a ba weight of about 73 gsm.

samples of the entangled material having a width of about inches were tested using the equipment and procedures of Exam 1. Values for Peak Load, Peak EA, Peak Percentage Elongati TEA and Total Percentage Elongation for the dry samples reported in Table 2 for the machine direction and the cro 5 machine direction.

EXAMPLE 3

A mixture of about 18.5 percent by weight hardwood pulp availa from the Weyerhauser Company under the trade designation Gr Q Regular, about 78.5 percent by weight uncrimped polyester sta fiber (1.5 denier x 12 mm) and about 3 percent by wei polyvinyl alcohol binder fiber was dispersed and then for continuously onto a foraminous surface at about 60 gsm. The was formed utilizing a continuous inclined wire paper mak 5 machine. The web was dried over a series of steam heated cans. Polyvinyl alcohol was added to facilitate reeling and handling.

The dried web was re-wetted and then entangled using the equipment and procedure of Example 1 on a standard 100 x 92 mesh stainless steel wire employing 6 passes at pressures of 1800 psi on each side of the sheet. The flow rate of the entangling water was 2.04 cubic meters per hour per inch of strip. The entangled sheets were air dried at ambient temperature. The dried material had a basis weight of about 53 gsm.

Samples of the entangled material having a width of about 4 inches were tested using the equipment and procedures of Example 1. Values for Peak Load, Peak EA, Peak Percentage Elongation, TEA and Total Percentage Elongation for the dry samples are reported in Table 3 for the machine direction and the cross- machine direction.

EXAMPLE 4 A mixture of about 19 percent by weight hardwood pulp available from the Weyerhauser Company under the trade designation Grade Regular, about 39 percent by weight uncrimped polyester staple fiber (1.5 denier x 12 mm), about 39 percent by weight uncrimped rayon staple fiber (1.5 denier x 12 mm) and about 3 percent by weight polyvinyl alcohol binder fiber was dispersed and then formed continuously onto a foraminous surface at about 60 gsm. The web was formed utilizing a continuous incline wire paper making machine. The web was dried over a series of steam heated cans. Polyvinyl alcohol was added to facilitate reeling and handling.

The dried web was pre-wetted and then entangled using the equipment and procedure of Example 1 on a standard 100 X 92 mesh stainless steel wire. Pre-wetting was done on one side at pressures of 200, 400 and 600 psi. Entangling on that side was performed at pressures of 800, 1000, 1200 and three passes 1500 psi. The other side of the material was entangled by passes at 1500 psi. The entangled sheets were air dried ambient temperature. The dried material had a basis weight about 53 gsm.

Samples of the dried and the entangled material having a wi of about 4 inches were tested using an Intellect II tens testing apparatus with a 3 inch jaw span and a crosshead speed about 10 inches per minute. Values for Peak Load, Peak EA Peak Strain are reported in Table 4 for the machine direct and the cross-machine direction for dry samples. Similar resu are also reported in Table 4 for wet samples.

For comparative purposes. Table 5 lists the Thickness Ind Isotropic Strength Index, abrasion test results, and dr stiffness test results for.the entangled material of Examples the entangled and unentangled material of Example 4, and commercially available materials which can be used for wipi Wiper A is a hydraulically entangled nonwoven material having trade designation Sontara, grade 8005 available E.I. duPont Nemours and Company. Wiper B is made from a wood pulp/sta fiber blend formed by laying a wood pulp web over a staple fi web and then hydroentangling the webs. wiper B has the tr designation Mohair Bleu and is available in France from Maury Nantes, France and from-Sodave of Angers, France. Table 5 a lists the thickness index and the isotropic strength index the identified materials.

As can be seen from Table 5, the hydroentangled materials f Examples 2 and 4 have a greater thickness index than unentangled material of Example 4, iper A and iper B. materials from Examples 2 and 4 also have a greater isotro strength index than Wipers A and B. Table 6 provides results of testing for the absorption rate, total absorptive capacity and mop-up capacity of the material from Example 4 for oil and water. The material of Example 2 had a total absorptive capacity and mop-up capacity for both oil and water which is significantly greater than the values for Wiper B.

Tables 7, 8 and 9 provide test results for the materials of the present invention and for various other wipers that are commercially available in Europe. Wiper CW1 is made of a meltblown polypropylene fabric. Wiper CW2 is a laminate of spunbonded polypropylene/meltblown polypropylene/spunbonded polypropylene. The wiper available under the trade designation MIRACLE WIPES is made of hydroentangled staple and cellulosic fibers. The wiper available under the trade designation CLEAN ROOM WIPERS is made of wet formed staple and cellulosic fibers. The wiper available under the trade designation DURX is made of hydroentangled staple and cellulosic fibers. The wiper available under the trade designation LABX is made of wet-formed staple and cellulosic fibers. The wiper available under the trade designation TEXWIPE is made of a 100 percent cotton woven fabric. The wiper available under the trade designation MICRONWIPE is made of hydroentangled staple and cellulosic fibers. The wipe available under the trade designation TEXBOND is made of spunbonded nylon fabric. The wiper available under the trad designation TECHNI-CLOTH is made of hydroentangled staple an cellulosic fibers.

For comparative purposes, Table 7 lists the results o extractablβ tests and sodium ion tests for the material o Example 2 and for some of the above-mentioned wipers. Als included in Table 7 are results for two materials made accordin Example 2. Material H contains about 80 percent by weight rayo staple fibers and about 20 percent by weight wood pulp. Materia F contains about 80 percent by weight polyester staple fibers an about 20 percent by weight wood pulp. Table 8 lists the result of electrical charge dissipation tests for the material of Example 2, Wiper A and for some of the above-mentioned wipers. Table 9 lists the results of Climet™ lint tests for the materials from Example 2, the entangled and untangled material from Example 4, Wiper A, and for some of the above-mentioned wipers.

As shown in Table 7, the materials of the present invention have levels of extractables which compare favorably with many commercial wipers. From Table 8, it can be seen that the materials of the present invention without any anti-static treatment have a static decay which is comparable with many commercial wipers. From Table 9, it can be seen that the materials of the present invention have relatively low lint levels and compare favorably with many commercial wipers.

Thus, it is apparent that the present invention provides a wiper

' that satisfies problems associated with previous wipers. While the invention has been described in conjunction with specific embodiments, the disclosed embodiments are intended to illustrate and not to limit the invention. It is understood that those of skill in the art should be capable of making numerous modifications without departing from the true spirit and scope of the invention.

TABLE 1

DRY

Peak Load (g)

Peak Energy Absorbed (kg-mm)

Peak Strain (%)

Total Energy Absorbed (kg-mm)

Total Strain ( )

WET

Peak Load (g) 7214

Peak Energy Absorbed (kg-mm) 117

Peak Strain (%) 120

Total Energy Absorbed (kg-mm) 196

Total Strain (%) 217

TABLE 2

TABLE 3

Peak Load (g)

Peak Energy Absorbed (kg-mm)

Peak Strai n (%)

Total Energy Absorbed (kg-mm)

Total Strain (%)

TABLE 4

TABLE 5

TABLE 6

OIL

Absorption Rate (sec.) 9.0 7.0

Total Absorptive Capacity (%) 596 230

Mop-Up Capacity 250 33

TABLE 7

EXTRACTABLES

TABLE 8

Notes: 1. Higher static decay times indicate increased tendency for static charge accumulation.

TABLE 9

CLIMET LINE (# PARTICLES

PRODUCT/CODE 10 u 0.5 u

CW1 0.4 112

CW2 0.1 9

Miracle Wipes* 1003 0.2 56

Clean Room Wipes^® 8025 0.2 4

Drux^® 670 0.4 442

Labx^® 123 0.4 428

Texwipe™ 309 2.6 5130

Micronwipe^® 500 0.7 498

Texbond™ 909 0.0 7

Techni-Cloth^® 609 0.6 358

Techni-Cloth^® II 1009 0.4 8

Example 2 2 65

Example 4 (Entangled) 0.8 76

Example 4 (Base Sheet) 2 72

Wiper A 0.8 51

Wiper B 0.2 286

Example 1 0.2 328

Claims

What is claimed is:

1. A hydraulically entangled coherent fibrous structur comprising: from about 10 to about 50 percent by weight wood pul fibers; and from about 50 to about 90 percent by weight of stapl fibers; and wherein said structure has a basis weight of from about 3 gsm to about 150 gsm and a thickness index of at least abou 0.008.

2. A hydraulically entangled coherent fibrous structur comprising: from about 10 to about 50 percent by weight wood pul fibers; and from about 50 to about 90 percent by weight of stapl fibers; and wherein said structure has a basis weight of from about 3 gsm to about 150 gsm and an isotropic strength index less th about 1.5.

3. A hydraulically entangled coherent fibrous structu comprising: from about 0 to about 50 percent by weight wood pu fibers; and from about 50 to ^:about 100 percent by weight of stap fibers; and wherein said structure has a basis weight of from about gsm to about 150 gsm and a thickness index of at least abo 0.008.

4. A hydraulically entangled coherent fibrous structu comprising: from about .0 to about 50 percent by weight wood pu fibers; and from about 50 to about 100 percent by weight of staple fibers; and wherein said structure has a basis weight of from about 30 gsm to about 150 gsm and an isotropic strength index less than about 1.5.

5. The structure of claim 1 wherein the staple fibers have a denier in the range of about 0.7 to about 3 and an average length in the range of about 5 mm to about 18 mm.

6. The structure of claim 1 wherein said staple fibers comprise one or more of rayon, cotton, polyesters, polyolefins, and polyamides.

7. The structure of claim 1 wherein the material has an oil absorption capacity of at least about 300 percent.

8. The structure of claim 1 wherein the material has a water absorption capacity of at least about 375 percent.

9. The structure of claim 1 wherein the material has a sodium ion content of less than about 150 parts per million.

10. A hydraulically entangled coherent fibrous structure comprising: from about 10 to about 50 percent by weight wood pulp fibers; and from about 50 to about 90 percent by weight of staple fibers; and wherein said structure has- a basis weight of from about 30 gsm to about 150 gsm, a thickness index of at least about 0.008 and a water absorption capacity of at least about 375 percent.

11. A hydraulically entangled coherent fibrous structur comprising: from about 10 to about 50 percent by weight wood pul fibers; and from about 50 to about 90 percent by weight of stapl fibers; and wherein said structure has a basis weight of from about 3 gsm to about 150 gsm, an isotropic strength index less tha about 1.5 and an oil absorption capacity of at least about 30

10 percent.

12. A hydraulically entangled coherent fibrous structur comprising: from about 0 to about 50 percent by weight wood pul fibers; and from about 50 to about 100 percent by weight of stapl fibers; and wherein said structure has a basis weight of from about 3 gsm to about 150 gsm, a thickness index of at least about 0.00 and a water absorption capacity of at least about 375 percent.

13. A hydraulically entangled coherent fibrous structur comprising: from about 0 to about 50 percent by weight wood pul fibers; and from about 50 to about 100 percent by weight of stapl fibers; and wherein said structure has a basis weight of from about 3 gsm to about 150 gsm, an isotropic strength index less than abou 1.5 and an oil absorption capacity of at least about 30

•10 percent.

14. The structure of claim 10 wherein the staple fibers have denier in the range of about 0.7 to about 3 and an average lengt in the range of about 5 mm to about 18 mm.

15. The structure of claim 10 wherein said staple fibers comprise one or more of rayon, cotton, polyesters, ^{^}polyolefins, and polyamides.

16. The structure of claim 10 wherein the material has a sodium ion content of less than about 150 parts per million.