MXPA00004422A - Liquid absorbent base web - Google Patents

Abstract

The present invention is generallydirected to base webs that are creped after a bonding material has been applied to at least one side of the web according to a predetermined pattern. The base web disclosed in the present application is made from at least three fibrous layers. The outer layers of the web contain synthetic staple fibers for increasing the tensile strength and abrasion resistant properties of the web. In one embodiment, the middle layer can further contain hardwood fibers, such as eucalyptus fibers, which improves the wipe dry properties of the web.

Description

BASE FABRIC ABSORBENT LIQUID Field of the Invention The present invention is generally directed to strong and abrasion resistant base fabrics that have good liquid absorption properties. The base fabric is generally made from a combination of pulp fibers and synthetic fibers. In one embodiment, the base fabric is used as a cleaning product.

Background of the Invention Liquid absorbent products such as paper towels, industrial cleaners, food service cleaners, napkins, medical pads and other similar products are designed to include several important properties. For example, products should have good volume, a soft feel and should be slightly absorbent. The products must also have good resistance even when wet and must be resistant to tearing. In addition, the products must have good stretch characteristics, must be resistant to abrasion, and must not deteriorate in the environment in which they are used.

In the past, many attempts have been made to improve and increase certain physical properties of such products. Unfortunately, however, when steps are taken to increase ownership of these products, other characteristics of the products may be adversely affected. For example, the softness of paper cleaning products can be increased by several different methods, such as by selecting a particular type of fiber, or by reducing the cellulosic fiber bond within the product. The increase in softness according to one of the methods, however, can adversely affect the strength of the product. Conversely, the steps normally taken to increase the strength of the fibrous tissue typically have an adverse impact on the softness or on the absorbency of the tissue.

A particular process that has proved to be very successful in producing paper towels and other cleaning products is described in United States Patent No. 3,879,257 issued to Gentile et al., Which is incorporated herein by reference in its entirety. in Gentile et al., a process is described for producing soft fibrous fabrics, single layer absorbers having a laminate type structure that are particularly suitable for use as cleaning products.

The fibrous tissues described in Gentile et al. Are formed from an aqueous solution of mainly lignocellulosic fibers under conditions which reduce the binding of the previous fiber. A binding material, such as a elastomeric latex composition, was applied to a first surface of the fabric in a spaced-apart pattern. In particular, a bonding material is applied so that it covers from about 50 to about 60% of the surface area of the fabric. The bonding material provides resistance to the fabric and resistance to abrasion to the surface. Once applied, the bonding material can penetrate the fabric preferably from about 10 to about 40% of the thickness of the fabric.

The bonding material can be similarly applied to the opposite side of the fabric to provide abrasion resistance and additional strength. Once the bonding material is applied to the second side of the fabric, the fabric can be brought into contact with a creping surface. Specifically, the fabric will adhere to the creping surface according to the pattern to which the bonding material was applied. The tissue is then creped from the creping surface with a doctor blade. The creping of the tissue greatly disrupts the fibers within the tissue, thereby increasing the softness, absorbency, and tissue volume.

In one of the preferred embodiments described in Gentile et al., Both sides of the paper web are creped after the bonding material has been applied. Gentile and others also discuss the use of chemical debonders to treat the fibers before forming the fabric in order to further reduce the interfiber bond and to increase softness and bulk.

Although the process described in Gentile et al. Has provided great advances in the art for making disposable cleaning products, the present invention is directed to further improvements in fibrous base fabrics. In particular, the present invention is directed to a fibrous base fabric having an improved combination of abrasion resistance, strength and dry cleaning properties. These and other advantages will be apparent from the following description.

Synthesis of the Invention As stated above, the present invention is directed to further improvements in the methods and constructions of the prior art, which are achieved by providing an abrasion-resistant liquid-absorbing base fabric. The base fabric may include a first outer fibrous layer defining a first side of the fabric and a second outer and opposite fibrous layer defining a second side of the fabric. The first and second outer layers may contain synthetic short fibers either alone or in combination with the pulp fibers. An intermediate fibrous layer can be placed between the first outer layer and the second outer layer. The intermediate layer may contain pulp fibers.

Desirably, a bonding material is applied to at least one side of the base fabric. In particular, the bonding material can be applied to the fabric according to a predetermined pattern, such as a geometric pattern. After the binding material is applied to at least one side of the fabric, the fabric can be creped. For example, in an embodiment the bonding material can be applied to both sides of the base fabric and both sides of the fabric can then be creped.

The synthetic short fibers contained within the base fabric of the present invention can be made of one or more polymers including polyester, nylon, polypropylene and rayon. The fibers may have a length of at least 0.25 inches and may have a denier of less than about 2.5, and particularly of less than 1.5. Synthetic fibers can be added to the base fabric in an amount of up to about 50% by weight and particularly from about 5 to about 15% by weight. In addition, each outer layer containing the synthetic fibers may comprise from about 15% to about 40% of the total weight of the fabric, and particularly * from about 25% to about 35% of the weight of the fabric.

In order to increase the softness and absorbent properties of the liquid of the base fabric, the intermediate fibrous layer may contain short pulp fibers having a low roughness, which create a pore size gradient between the outer layers and the inner layer. It is believed that by creating a pore size gradient, the base fabric has improved transmission properties. The short fibers having a low roughness that can be included in the intermediate layer include hardwood fibers, such as eucalyptus fibers or eucalyptus type fibers. For example, the fibers may have a length of less than about 2.0 millimeters and a roughness of less than about 10. Hardwood fibers may be present within the base web in an amount of from about 10% to about of 40% by weight.

Other fibers that can be incorporated within the intermediate fibrous layer in order to improve the dry cleaning properties of the fabric include the highly wettable and highly absorbent fibers of the liquid. For example, such fibers can include highly extracted pulp fibers such as mercerized alpha fibers. The alpha pulp can be made of soft wood fibers or hardwood fibers and can be present in the intermediate layer either alone or in a combination with the fibers described above.

The bonding material applied to the base fabric can be applied in a pattern covering from about 10% to about 60%, and more particularly from about 20% to about 50% of the surface area of each side of the fabric base. The bonding material may be applied to each side of the base fabric in an amount of up to about 10% by weight, and particularly from about 5% to about 8% by weight. Once applied, the bonding material can penetrate the fabric in an amount of from about 15% to about 50% of the total thickness of the fabric.

The preselected pattern used to apply the bonding material can be, in one embodiment, an interconnected network design. Alternatively, the preselected pattern may comprise a succession of discrete points. The binding material can be for example a latex, for example such as a copolymer of ethylene vinyl acetate crosslinked with N-methyl acrylamide groups. Vinyl acrylic copolymers with cross-linking capability are also useful.

Once formed, the base fabric of the present invention can have a basis weight of from about 20 pounds per ream to about 80 pounds per ream, depending on the particular application. The base fabric can be used in numerous products. For example, the base fabric can be used as a cleaning product, such as a towel, as a medical pad, or as a table cloth, as a cover material, such as a car cover, such as a paint drop cloth. , as a layer in rolled product or as any other similar liquid absorbent product.

These and other features are also achieved by providing a method for producing a base fabric. The method to include first providing a fibrous tissue having a middle layer containing pulp fibers, such as hardwood fibers. The base fabric may further include a first outer layer containing synthetic short fibers and a second outer layer also containing synthetic short fibers. The synthetic short fibers may be present within the outer layers either alone or in combination with the pulp fibers.

A first bonding material may be applied to the first side of the fabric in a preselected pattern and, if desired, a second bonding material may be applied to the second side of the fabric also in a preselected pattern. Once the binding materials are applied to the tissue, the tissue can then be creped. For example, the fabric can be adhered to a creping surface and then creped from the surface using for example, a creping blade.

Other features and aspects of the present invention are discussed in more detail below.

Brief Description of the Drawings A total and enabling description of the present invention, including the best mode thereof for one with ordinary skill in the art is more particularly set forth in the remainder of the description including reference to the accompanying figures in which: Figure 1 is a schematic diagram of a fibrous web forming machine illustrating an embodiment for forming a base fabric having multiple layers according to the present invention.

Figure 2 is a schematic diagram of a fibrous tissue forming machine that crepes one side of the tissue; Y Figure 3 is a schematic diagram of an embodiment of a system for a double creping of a base fabric according to the present invention.

The repeated use of the reference characters in the present description and drawings is intended to represent the same or analogous elements or features of the present invention.

Brief Description of Preferred Additions It should be understood by one of ordinary skill in the art that the present discussion is a description of example embodiments only and is not intended to limit the broad aspects of the present invention, the broader aspects of which are involved in the example construction.

In general, the present invention is directed to a strong abrasion-resistant base fabric. Of particular advantage, in one embodiment, the base fabric is made with improved strength while maintaining good softness characteristics and liquid absorbency properties. In particular, the base fabric contains an extremely efficient transmission mechanism which transports fluid from the surface of the base fabric to the interior of the fabric. In addition, the base fabric has good stretch characteristics, is tear resistant and does not produce a substantial amount of lint when in use.

The base web of the present invention can have a multi-layer construction. In particular, the fabric can be made from a stratified fiber supply having three main layers. According to the present invention, the outer layers of the fabric contain short synthetic fibers, such as polymer fibers. The synthetic fibers in the outer layers of the fabric make the fabric resistant to surface abrasion and reinforce the tensile strength properties of the fabric or fabric.

In one embodiment, the base fabric may also include an intermediate layer containing relatively short fibers having a low roughness value or other highly wettable and absorbent fibers. For example, the intermediate layer may contain hardwood fibers, such as eucalyptus fibers or eucalyptus type fibers. The hardwood fibers contained within the intermediate layer create a pore and capillary size gradient between the outer layers and the intermediate layer. This capillary and pore size gradient increases the transmission properties of the base fabric, providing the fabric with improved liquid absorbing properties. The middle layer of the fabric counteracts the hydrophobicity of the synthetic fibers by causing the fluids that contact the liquid to be transported inside the tissue. In addition, since the hardwood fibers are contained in the intermediate layer, the base fabric does not create a substantial amount of lint when in use.

The base fabric of the present invention may further include a binding material that is applied to at least one side of the fabric, and desirably to both sides of the fabric. After the bonding material is applied, the fabric can be creped at least on one side and preferably on both sides. More particularly, the bonding material can be applied to the fabric in a preselected pattern to provide strength and stretchability without adversely affecting the softness of the fabric. Creping tissue increases softness and tissue volume.

As indicated above, one aspect of the present invention is directed to incorporating synthetic short fibers into the outer layers of the base fabric. As used herein, synthetic short fibers refer to fibers made of one or more synthetic materials, such as polymeric materials, and may include single component or multi component fibers such as bicomponent fibers. The bicomponent fibers refer to fibers made of two different polymers such as in a side-by-side arrangement or in a sheath and core arrangement. The particular materials which can be used to build the synthetic fibers include nylon, polypropylene and rayon. In a preferred embodiment, the polyester fibers are used.

In general, the length and denier of the synthetic fibers will depend on the particular application and the manner in which the base fabric is formed. For most applications, the fibers must have a length of at least 0.25 inches, such as from about 0.25 inches to about 0.75 inches. Longer fibers which can improve the strength of the fabric however, can be used.

The denier of the fibers, on the other hand, is preferably relatively low. For example, the denier of the fibers can be less than about 2.5 dpf and particularly less than about 1.5 dpf. By using smaller denier fibers, less material may be required in tissue formation.

The synthetic short fibers should be incorporated within the outer layers of the fabric in an amount sufficient to increase the abrasion resistance and tensile strength properties of the fabric. The amount of synthetic fibers added to the fabric will generally depend on the particular application. In most embodiments, synthetic fibers may be present within the fabric in an amount of up to about 50% by weight, and particularly from about 5% to about 15% by weight. In addition, for most applications, the amount of the synthetic fibers contained within one of the outer layers of the base fabric will be essentially equal to the amount of the synthetic fibers contained within the opposite outer layer of the base fabric.

The weight of each outer layer in relation to the total weight of the fabric is generally not critical. In most embodiments, however, the weight of each outer layer will be from about 15% to about 40% of the total weight of the fabric, and particularly from about 25% to about 35% of the weight of the fabric. tissue.

In addition to the synthetic short fibers, the outer layers may also contain pulp fibers, such as various cellulosic fibers, for example, in one embodiment, the northern softwood kraft fibers may be combined with the synthetic fibers. Soft wood fibers generally have a fiber length of from about 1.8 millimeters to about 3 millimeters. Preferably, the pulp fibers are homogenously mixed with the synthetic short fibers.

The middle layer of the base fabric of the present invention may contain various types of fibers. In a preferred embodiment, the middle layer contains hardwood fibers either alone or in combination with the soft wood fibers. In particular, softwood fibers can be added to the middle layer to create a capillary and pore size gradient between the outer layers and the middle layer, which creates a highly efficient transmission mechanism as described above.

More particularly, the hardwood fibers incorporated within the middle layer of the base fabric must have a relatively short fiber length rating and relatively low roughness, which serve to create the pore size gradient described above. For example, hardwood fibers can have a length of less than about 2 millimeters, and particularly less than about 1.5 millimeters. The roughness rating of the fibers, on the other hand, can be less than 10, and particularly less than 8, as determined on a KAJANNI fiber test machine.

In one embodiment, the hardwood fibers incorporated within the middle layer of the base weave include the eucalyptus fibers. Eucalyptus fibers typically have a length of from about 0.8 millimeters to about 1.2 millimeters. When added to the fabric, eucalyptus fibers increase softness, improve brilliance, increase opacity, and increase the ability to transmit tissue.

In addition to eucalyptus fibers, other eucalyptus type fibers may also be incorporated into the base fabric of the present invention. As used herein, eucalyptus type fibers refer to fibers that have characteristics similar to eucalyptus fibers. Such fibers include, for example, birch fibers and possibly recycled wood fibers.

In addition to the hardwood fibers described above, other fibers particularly suitable for use in the middle layer of the base fabric are the highly absorbent and wettable fibers, such as those produced when the wood pulp is highly extracted. For example, the mercerized alpha pulp can be incorporated into the base fabric. The alpha pulp may contain softwood fibers or hardwood fibers. Since the alpha pulp is highly humid- able, the pulp will increase the dry cleaning properties of the base tissue similar to eucalyptus fibers. Alpha pulp is commercially available from, for example, IT Rayonier.

In general, the hardwood fibers described above or the alpha pulp may be present in the base fabric in an amount of from about 10% to about 40% by weight and particularly in an amount of about 20% by weight. The fibers may comprise from about 5% to about 100% by weight of the middle layer of the fabric.

As stated above, hardwood fibers or alpha pulp fibers may be present within the middle layer of the fabric either alone or in combination with other fibers, such as other cellulosic fibers. For example, hardwood fibers can be combined with softwood fibers, and with recycled fibers, with superabsorbent materials, and with thermomechanical pulp. In addition to the fibers, any material that can improve a property of the base fabric can also be included within the middle layer.

The multilayer base fabric made according to the process of the present invention, for most applications, must be formed without a substantial amount of fiber to inner fiber bond strength. In this aspect, the fiber supply used to form the base fabric can be treated with a chemical binder agent. The debinding agent can be added to the fiber solution during the pulping process or can be added directly into the headbox. Suitably, the binder agents which can be used in the present invention include the cationic debinding agents such as the quaternary dialkyl fatty amine salts, the ammonium fatty acid tertiary amine salts, the primary amine salts, the quaternary imidazoline salts, and the alkyl amine salts of unsaturated fatty acids. Other suitable binder agents are described in U.S. Patent No. 5,529,665 issued to Kaun which is incorporated herein by reference.

In a preferred embodiment, the deagglutinating agent used in the process of the present invention may be an organic quaternary ammonium chloride. In this embodiment, the debinding agent can be added to the fiber solution in an amount of from about 0.1% to about 1% by weight, based on the total weight of the fibers present within the solution.

The manner in which the base web of the present invention is formed may vary depending on the particular application. For example, in an embodiment the fabric can be formed in a wet-laid process according to conventional papermaking techniques. In a wet-collocated process, the fiber supply is combined with water to form an aqueous suspension. The aqueous suspension is spread on a wire or felt and dried to form the fabric.

Alternatively, the base fabric of the present invention can be formed by air, in this embodiment, the air is used to transport the fibers and form a fabric. Air forming processes are typically capable of processing fibers longer than most wet laying processes, which may provide an advantage in some applications.

Referring to Figures 1-3, an embodiment of a process for producing a base fabric according to the present invention is illustrated. The process illustrated in the figures shows a wet laying process, although as described above, other techniques for forming the base fabric of the present invention can be used.

Referring to Figure 1, an embodiment of a device for forming a multi-layer stratified fiber supply is illustrated. As shown, a three layer head box generally indicated with the numeral 10 can include a top head box wall 12 and a lower head box wall 14. The head box 10 can further include a first divider 16 and a second divider 18, which separates three layers of fiber supply.

Each of the fiber layers comprises a dilute aqueous suspension of fibers. According to the present invention, as described above, the middle layer 20 may contain hardwood fibers, or softwood fibers, or a combination of both. The outer layers 22 and 24, on the other hand, contain synthetic short fibers alone or in combination with pulp fibers, such as soft wood fibers.

An endlessly moving forming fabric 26, suitably supported and driven by the rollers 28 and 30, receives the layered supply coming out of the head box 10. Once retained on the fabric 26, the layered fiber suspension passes to through the fabric as shown by the arrows 32. The removal of water is achieved by combinations of gravity, centrifugal force and suction with vacuum depending on the forming configuration.The formation of multilayer fabrics is also described and disclosed in U.S. Patent No. 5,129,988 issued to Farrington, Jr. and in U.S. Patent No. 5,494,554 issued to Ed ards and others, which are incorporated here by reference.

Referring to Figure 2, there is illustrated an embodiment of a base woven forming machine capable of receiving the fiber suspension in layers of the head box 10 and forming a fabric. As shown in this embodiment, the forming fabric 26 is supported and propelled by a plurality of guide rollers 34. A vacuum box 36 is positioned below the forming fabric 26 and is adapted to remove water from the fiber supply to assist in the formation of a fabric.

From the forming fabric 26, a formed fabric 38 is transferred to a second fabric 40, which may be a wire or a felt. The fabric 40 is supported for movement about a continuous path by means of a plurality of guide rollers 42. A take-up roller 44 designed to facilitate the transfer of the fabric 38 from the fabric 26 to the fabric 40 is also included. Preferably , at the speed at which the fabric is driven is approximately the same speed at which the fabric 26 is driven so that the movement of the fabric 38 through the system is consistent.

From the fabric 40, the fabric 38 in this embodiment is transferred to the surface of a rotary heated dryer drum 46, such as a Yankee dryer. The fabric 38 is pressed lightly into contact with the drum surface of the dryer 46 to which it adheres, due to its moisture content and its preference for the smoother of the two surfaces. As the fabric 38 is carried through a portion of the rotational path of the dryer surface, heat is imparted to the fabric causing most of the moisture contained within the fabric to evaporate.

In an alternate embodiment, the fabric 38 can be dried continuously instead of being placed on a dryer drum. A continuous dryer achieves the removal of moisture from the fabric by passing air through the fabric without applying any mechanical pressure. Continuous drying can increase the volume and softness of the fabric.

From the dryer drum 46, as shown in Figure 2, the fabric 38 is pressed into contact with the creping dryer 45 by a press roll 43. The press roll 43 in combination with the creping dryer 45 applies a sufficient amount of heat and pressure to the fabric 38 to cause the fabric to adhere to the creping dryer surface without the use of an adhesive. However, if desired, an adhesive can be applied on the surface of the drum fabric to facilitate the attachment of the fabric to the drum.

The fabric 38 is then removed from the dryer drum 45 by means of a creping blade 47. The creping fabric 38 being formed reduces the internal bond within the fabric and increases softness.

The base fabric formed of the process illustrated in Figure 2 has certain physical characteristics that are particularly advantageous for use in the remainder of the process of the present invention. In particular, the fabric 38 is characterized by having a reduced amount of inner fiber bond strength. As described above, the fabric may also have hardwood fibers. The low bond strength in combination with hardwood fibers provides softness, volume, absorbency, opacity, transmission capacity and brilliance. As will be described hereafter, the remainder of the process of the present invention is designed not only to improve the aforementioned properties but also to provide the paper fabric with strength and stretchability.

Once the paper web 38 is formed, a bonding material can be applied to at least one side of the fabric and at least the side of the fabric can then be creped. For most applicationsDesirably a bonding material is applied to both sides of the fabric and both sides of the fabric are creped. When the base web of the present invention is used in a multilayer laminate, however, it may be desired to only apply the bonding material to one side of the fabric. For example, when a two-layer product is made, base fabrics made in accordance with the present invention can be worn together and joined along adjacent surfaces where the bonding material has not been applied.

Referring to Figure 3, a process for applying a bonding material to both sides of the fabric and to creping both sides of the fabric in accordance with the present invention is illustrated.

As shown, desirably, the base fabric 38 made according to the process illustrated in Figure 2 or according to a similar process, is passed through a first binding material application station indicated generally at 50. station 50 may include a pressure point formed between a smooth rubber press roll 52 and a patterned rotogravure roller 54. The rotogravure roller 54 may be in communication with a reservoir 56 that contains a first bonding material 58. The rotogravure roller 54 applies to the bonding material 58 on one side of the fabric 38 in a preselected pattern.

The fabric 38 is then pressed to a contact with a first creping drum 60 by means of a press roll 62. The bonding material causes only those parts of the fabric where it has been placed to adhere to the creping surface. If desired, the creping drum 60 can be heated to promote clamping between the tissue and the surface of the drum and to partially dry the fabric.

Once adhered to the creping drum 60, the fabric 38 can be brought into contact with the creping blade 64. Specifically, the fabric 38 can be removed from the creping roller 60 by the action of the creping blade 64, carrying out a first creping pattern controlled on the tissue.

Once creped, the fabric 38 can be advanced by the pull-down rollers 66 to a second binding material application station generally indicated with the number 68. The station 68 can include a transfer roller 70 in contact with a rotogravure roller. 72, which may be in communication with a reservoir 74 containing a second attachment material 76. Similar to station 50, a second attachment material 76 may be applied to the opposite side of tissue 38 in a preselected pattern. Once the second binding material is applied, the fabric 38 can be adhered to a second creping roller 78 by means of a press roll 80. Desirably, the fabric 38 is carried on the surface of the creping drum 78 by a distance and then it is removed from it by the action of a second sreening towel 82. The second creping blade 82 performs a second creping operation with controlled pattern on the second side of the base fabric.

Once creped for a second time, the base fabric 38, in this embodiment, is pulled through a drying or curing station 84. The drying station 84 can include any form of heating unit, such as from an oven energized by infrared heat, microwave energy, hot air or the like. The drying station 84 may in some applications necessarily dry the fabric and / or cure the first and second bonding materials. Depending on the selected bonding materials, however, in other applications, the drying station 84 may not be necessary.

Once pulled through the drying station 84, the fabric 38 can be wound onto a roll of material 86 for immediate use or for further processing according to the present invention.

The bonding materials applied on each side of the base fabric 38 are selected to not only aid in the creping of the fabric but also to assist in dry strength, wet strength, stretchability, and tear resistance for the fabric. The bonding materials also prevent the lint from escaping from the fabric during use.

The bonding material can also be applied to the base fabric as described above in a preselected pattern. In one embodiment, for example, the binder can be applied to the fabric in a lattice pattern, so that the pattern is interconnected forming a network type design on the surface.

In an alternate embodiment, the bonding material can be applied to the fabric in a pattern representing a succession of points or other geometric shapes. By applying a bonding material in discrete shapes, such as stitches, fabric strength is provided without covering a substantial part of the surface area of the fabric.

In general, according to the present invention, the bonding material can be applied to each side of the base fabric as to cover from about 10% to about 60% of the surface area of the fabric. More particularly, for most applications, the bonding material will cover from about 20% to about 50% of the surface area of each side of the fabric. The amount of the bonding material applied to each side of the fabric will desirably be in the range of about 3% to about 10% by weight, and particularly from about 6% to 8% by weight, based on the total weight of the tissue. For example, in one embodiment, the bonding material can be applied to each side of the fabric in an amount of about 7% by weight.

At the above-mentioned amounts, the bonding material can penetrate into the base fabric from about 25% to 50% of the thickness of the fabric. In most applications, the bonding material must at least penetrate from about 10% to about 15% of the thickness of the fabric.

Particular binding materials that can be used in the present invention include latex compositions such as acrylates, vinyl acetates, vinyl chlorides and methacrylates. Some water-soluble binding materials can also be used including polyacrylamides, polyvinyl alcohols, and carboxymethyl cellulose.

In a preferred embodiment, the binding material used in the process of the present invention comprises a copolymer of ethylene vinyl acetate. In particular, the ethylene vinyl acetate copolymer is desirably crosslinked with N-methyl acrylamide groups using an acid catalyst. Suitable acidic catalysts include ammonium chloride, citric acid, and maleic acid. The bonding material must have a glass transition temperature of not lower than -10 ° F and not higher than + 20 ° F.

The base fabrics made according to the process described above provide many advantages and benefits over conventional constructions. In particular, the base fabrics made according to the present invention have improved abrasion resistance properties and improved tensile strength properties. In fact, it has been found that the base fabrics made according to the present invention have a total stress resistance (resistance to the transverse direction plus machine direction) which is much higher at higher volumes than many constructions of the machine. previous art Further, when the base fabric of the present invention contains hardwood fibers or other highly wettable fibers as described above, the fabric strength is improved while at the same time creating a fabric with good cleaning drying properties.

The basis weight of the base fabrics made according to the present invention may vary depending on the particular application. In general, for most applications, the basis weight can be from about 20 pounds per 2,880 square feet (ream) to about 80 pounds per ream. Some of the uses of the base fabrics include use as a cleaning product, such as a napkin, as a medical pad, as an absorbent layer in a laminated product, such as a single tablecloth, such as a drop cloth, as a dressing material. cover, or for any product that requires liquid absorbency.

The present invention should be better understood with reference to the following example.

EXAMPLE The following example was carried out in order to compare a base fabric made according to the present invention with a base fabric which has been used in the past as a cleaning product.

A base weave made in accordance with the present invention was produced according to a process similar to that illustrated in Figures 1-3. The base fabric contained a middle layer separated by two outer layers. In particular, each outer layer accounted for about 26% by weight of fabric while the middle layer accounted for about 47% of the weight of the fabric.

In accordance with the present invention, each outer layer contained polyester edges. The polyester fibers were present within the fabric in a total amount of about 8% by weight (4% by weight in each outer layer). In this arrangement, polyester fibers accounted for about 15% of the surface fibers. The rest of the outer layers was composed of pulp fibers, specifically soft wood fibers.

The middle layer contained a mixture of soft wood fibers and eucalyptus fibers. The eucalyptus fibers will be present in the base fabric in an amount of 20% by weight, as for the account by about 42% by weight of the middle layer.

After the base fabric was formed, a bonding material was printed on each side of the fabric and both sides of the fabric were creped. The binding material used was an ethylene vinyl acetate latex. The bonding material was applied to each side of the fabric according to a small diamond-shaped pattern. The bonding material was also applied to one side of the weave according to a larger diamond shape pattern for the most part to improve the aesthetic appearance of the base fabric.

It was noted that the resulting base fabric had good feel and good aesthetic appearance. Four samples of the base fabric were tested and the following results were obtained: Table 1: Results of the Base Tissue made according to the Present Invention The above-mentioned base fabric was compared to a multi-layer base fabric conventionally made containing polyester fibers in the middle layer. In the past, polyester fibers were incorped into the middle layer of the base fabrics in order to increase the strength of the fabrics.

The conventionally made base fabric included two outer layers made of soft wood fibers and a middle layer containing a mixture of soft wood fibers and polyester fibers. The polyester fibers were present within the middle layer in an amount of 15% by weight of the middle layer. Each layer of the fabric accounted for one third of the total weight of the fabric.

Similar to the base fabric described above made according to the present invention, a binding material was applied to each side of the conventionally made fabric and the fabric was creped on both sides.

Five core samples made conventionally were tested and the results are as follows.

Table 2: Results of a Conventional Fabric Made Conventionally Containing Polyester Fibers in the Medium Layer As shown above when comparing the two tables, the base fabric made according to the present invention had much better stretch properties and tensile strength in the machine direction than the conventionally made fabric. The resistance to the total tension of the base fabric made according to the present invention is much greater compared to the constructions of the prior art, especially at the level of volume that was tested. Furthermore, even though the resistance in the transverse direction and the stretching properties were not as good as those of conventionally made fabric, the base fabric of the present invention had better resistance in the transverse direction when wetted. In addition, because the base fabric of the present invention contains synthetic fibers on the outer layers, the fabric must have better abrasion resistance properties than the conventionally made fabric.

These and other modifications and variations to the present invention can be practiced by those with ordinary skill in the art., without departing from the spirit and scope of the present invention which is more clearly stated in the appended claims. In addition, it should be understood that the aspects of the various incorporations can be exchanged both in whole and in part. In addition, those of ordinary skill in the art will appreciate that the foregoing description is only by way of example only, and that no attempt is made to limit the invention as further described in such appended claims.

Claims (26)

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

1. An abrasion-resistant liquid absorbent base fabric comprising: a first outer fibrous layer defining a first side of said base fabric and a second outer and opposite fibrous layer defining a second side of said base fabric, said first and second outer layers containing synthetic short fibers; an intermediate fibrous layer placed between said first outer layer and said second outer layer, said intermediate layer comprising pulp fibers; a bonding material applied to at least one of said sides of said base fabric, said bonding material being applied to said at least one side according to a predetermined pattern; Y wherein said at least one side of said base weave is creped after said joint material has been applied.

2. A base fabric, as claimed in clause 1, characterized in that said synthetic short fibers comprise fibers containing polyester, nylon, polypropylene, rayon or mixtures thereof.

3. A base fabric, as claimed in clause 1, characterized in that said synthetic short fibers have a length of at least 0.25 inches and have a denier of less than about 2.5.

4. A base fabric, as claimed in clause 1, characterized in that said synthetic short fibers are present within said fabric in an amount of up to about 50% by weight.

5. A base fabric, as claimed in clause 1, characterized in that said first and second outer layers further contain pulp fibers combined with said synthetic short fibers.

6. A base fabric, as claimed in clause 1, characterized in that said synthetic short fibers are present within said fabric in an amount of from about 5% to about 15% by weight.

7. A base fabric, as claimed in clause 1, characterized in that said synthetic short fibers comprise polyester fibers.

8. A base fabric, as claimed in clause 1, characterized in that said intermediate layer comprises hardwood fibers having a fiber length of less than about 2 millimeters.

9. A base fabric, as claimed in clause 1, characterized in that a joining material is applied to said first side of said fabric and to said second side of said fabric and in which both sides of said fabric are creped.

10. A base fabric, as claimed in clause 1, characterized in that said intermediate layer comprises alpha pulp fibers.

11. A base fabric absorbent to the abrasion resistant liquid comprising: a first outer fibrous layer defining a first side of said base fabric and a second outer and opposite fibrous layer defining a second side of said base fabric, said first and second outer layers comprising a blend of synthetic short fibers and pulp fibers , said synthetic short fibers contain a material selected from the group consisting of polyester, nylon, polypropylene, rayon and mixtures thereof, each of said first and second outer layers comprise from about 15% to about 40% by weight of said base fabric; an intermediate fibrous layer placed between said first outer layer and said second outer layer, said intermediate layer comprises fibers having a length of less than about 2.0 millimeters and a roughness of less than about 10; a bonding material applied to at least one of said sides of said base fabric, said bonding material being applied to said at least one side according to * a predetermined pattern; Y wherein said at least one side of said base web is creped after the bonding material has been applied.

12. A base fabric, as claimed in clause 11, characterized in that a bonding material was applied to said first side of said fabric and said second side of said fabric and in which both sides of said fabric are creped.

13. A base fabric, as claimed in clause 11, characterized in that said synthetic short fibers are present within the base fabric in an amount of from about 5% to about 15% by weight.

14. A base fabric, as claimed in clause 11, characterized in that said fibers contained within said intermediate layer comprise eucalyptus fibers or eucalyptus type fibers.

15. A base fabric, as claimed in clause 11, characterized in that said fibers contained within said intermediate layer comprise hardwood fibers.

16. A base fabric, as claimed in clause 11, characterized in that said fibers contained within said intermediate layer are aggregated in an amount of from about 10% to about 40% by weight of said base fabric.

17. A base fabric, as claimed in clause 11, characterized in that said fibers contained within said intermediate layer are aggregated in an amount sufficient to create a pore size gradient between said intermediate layer and said first and second outer layers.

18. A method for producing a liquid absorbent base fabric comprising the steps of: providing a fibrous fabric including a middle layer comprising hardwood fibers or alpha pulp fibers, a first outer layer comprising a mixture of pulp fibers and synthetic short fibers, and a second outer layer also comprising a mixture of pulp fibers and synthetic short fibers, said fibrous fabric having a first side and a second side; applying a first bonding material to said first side of said fabric in a preselected pattern and adhering said first side a of said fabric to a first creping surface; Y creping said first side of said fabric from said first creping surface.

19. A method, as claimed in clause 18, characterized in that it comprises the steps of applying a second joining material to said second side of said fabric in a pre-selected pattern and adhering said second side of said fabric to a second creping surface; Y creping said second side of said fabric from said second creping surface.

20. A method, as claimed in clause 18, characterized in that said synthetic short fibers are present within said fabric in an amount of up to about 50% by weight, said synthetic short fibers contain a material selected from the group consisting of of polyester, nylon, polypropylene, rayon and mixtures thereof.

21. A method, as claimed in clause 18, characterized in that said middle layer comprises a mixture of pulp fibers and hardwood fibers, said hardwood fibers comprising eucalyptus fibers or eucalyptus type fibers.

22. A method, as claimed in clause 19, characterized in that said first joining material and said second joining material are each applied to said base fabric in an amount of up to about 10% by weight, said joining materials first and second are applied to said base weave in a pattern that covers from about 20% to about 50% of the surface area of said first and second sides of said base fabric respectively.

23. A cleaning product comprising: a base fabric including a first outer fibrous layer defining a first side of said base fabric and a second outer and opposite fibrous layer defining a second side of said base fabric, said first and second outer layers comprise a mixture of synthetic short fibers and pulp fibers, said synthetic short fibers being present within said cleaning product in an amount of from about 5% to about 15% by weight, each of the first and second outer layers comprises from about from 15% to about 40% of the weight of said base fabric; an intermediate fibrous layer placed between said first outer layer and said second outer layer, said intermediate layer comprising fibers of wood pulp or fibers of alpha pulp, said fibers of wood pulp or said fibers of alpha pulp being present within said base fabric in an amount of from about 10% to about 40% by weight; a bonding material applied to said first side of said base weave according to a first predetermined pattern and said second side of said base fabric according to a second predetermined pattern; Y wherein said first side and said second side of said base weave are creped after the joint material has been applied.

24. A cleaning product, as claimed in class 23, characterized in that said synthetic short fibers comprise polyester fibers.

25. A cleaning product, as claimed in clause 23, characterized in that said intermediate layer comprises wood pulp fibers, said wood pulp fibers comprising eucalyptus fibers or eucalyptus type fibers.

26. A cleaning product, as claimed in clause 25, characterized in that said intermediate layer also contains soft wood fibers. R E U M E N The present invention is generally directed to base fabrics that are creped after a bonding material has been applied to at least one side of the fabric according to a predetermined pattern. The base fabric described in the present application is made of at least three fibrous layers. The outer layers of the fabric contain synthetic short fibers to increase the tensile strength and abrasion resistance properties of the fabric. in an embodiment, the middle layer may also contain hardwood fibers, such as eucalyptus fibers, which improves the drying properties of fabric cleaning.