Patent Description:
Nowadays, various kinds of products a part of which contains the water absorbing body have been supplied. The water absorbing body is a sanitary goods in which a water absorbing property is required. For instance, a paper diaper, a paper diaper for animals, a training pad, a sanitary napkin, a sweat pad, an incontinence pad, a support sleep sheet, a care support sheet, etc. are enumerated as examples.

In a process for producing the paper diapers containing a water absorbing body, for instance, a back sheet is fed from a web roll to be transported on mesh belt, and short fibers which is a material for the water absorbing body are rested on such a back sheet. Thereafter, tissues, gathers or top sheets fed from the web roll are fed on a no-woven fabric to be cut into a desired size by means of a side cutter, an end cutter, as needed, whereby the water absorbing body is produced as a final product via a bending device. Patent Publication <NUM>, for instance, discloses such a structure of the water absorbing body, and the method of producing the water absorbing body.

Such a mesh belt used in the has been known to have a short produce life. The present inventor found out causes for the short product life, that is, the meandering of the mesh belt in the conveyor on the apparatus for producing the water absorbing body. The applicant took measures to adjust the meandering of the mesh belt by providing a guide roll on the mesh belt, for instance, but it did not turn out to be sweeping countermeasures,.

Such being the case, the present inventor paid attention to the powder material stuck on the transfer roll in order to identify the causes for the meandering of the mesh belt on the conveyor. It was found out that the generation of such a powder material causes the mesh belt to slide, or tilt on the transfer roll to causes irregularities of the normal running of the mesh belt, whereby the direction in which the mesh belt is run is meandered, or the end portion of the mesh belt was turned up.

The present inventor found out that a relatively light pulp fibers, or chemical fibers are used in short fibers for the material of the water absorbing body, in a case where the causes for the scattering of the power material were further investigated. In addition, it was found out that, in the mesh belt at present constituted by plastic resin warps and plastic resin wefts, a static electricity was generated between the yarns constituting such a fabric and the short fibers. More specifically, the powder material was scattered due to the static electricity generated on the mesh belt, so that the conventional technical problems have arisen doe to such the scattered powder material.

For instance, the material of the water absorbing body of the diaper is normally constituted mainly by the pulp fibers and high molecule absorbing polymers. Such high molecule absorbing polymers are neither used in the normal water-absorbing paper, nor in the normal non-woven fabric. The present inventor assumed that high molecule absorbing polymers which is a material for the water absorbing body bears a negative charge, while that the pulp fibers bear the positive charge. Such being the case, since the mesh belt formed by the plastic wires made of the conventional resin, etc. or the metal tends to bear the negative charge due to the excessive electrons on the surface of the fabric, the above-described high molecule absorbing polymers and the pulp fibers repulse with each other, so that the powder material for the water absorbing body was caused to scatter. In an actual process for producing the water absorbing body, the mesh belt and the powder material for the water absorbing body do not contact directly, it was found out that the static electricity born on the mesh belt directly influences on the powder material to cause the scattering of the powder material, since the back sheet is not made of an electrically insulating material.

In this connection, the present inventor investigated Patent Publication <NUM> disclosing the technique concerning the prevention of the electrically charging used in the producing of the non-woven fabric. In the Patent Publication <NUM>, the technique in which a structure made of an electrically conductive material is laminated on the lower surface of the mesh belt. However, since the different structure and material are laminated in this technique, the desired rigidity and the desired dehydration property for the mesh belt are not fulfilled.

In addition, Patent Publication <NUM> discloses a fabric in which flat longitudinal yarns with an electrically conductive material are used. However, since this technique is preferably applied to a fabric used in an air blown part, no attention was paid to the dehydration, the surface smoothness of the fibers, fiber supportability, the improvement of the yield of the powder material, the dimensional stability, the running stability, etc., so that the desired properties required for the mesh belt are not attained.

Accordingly. By intensive studies carried out by the present inventor, the mesh belt including the electrically discharging property fitted for an apparatus for producing the water absorbing body was developed.

<CIT> relates to a conveyor belt for conveying bulk materials having low specific density under vacuum. The woven conveyor belt for transporting bulk materials with low specific weight under vacuum comprises a weft filament which is combined with warp filaments in such a way that one side of the belt is rendered smooth, while its opposite side is extremely rough for better transport of such materials.

<CIT> relates to a method of connecting the ends of screen fabrics for producing endless forming wires for paper machines. The end portions of a woven screen fabric strip having synthetic plastic warp wires are interconnected to produce an endless forming wire for a paper-making machine by heat setting the corrugated ends of the wires in both edge portions of the strip; cutting the ends of adjacent wires in each portion to different lengths and complementary to the lengths of the ends of the wires in the other portion; removing the cut-off parts of the wires; removing at least some of the weft wires from the marginal areas between the shortest and longest ends so as to expose these ends; and inserting new weft wires to connect the projecting ends of both portions with each other. In one embodiment, the synthetic plastic warp wires of the portion are graphically distinguished from the synthetic plastic warp wires of the portion by an additional centre line. Metal weft wires and synthetic plastic weft wires alternate. After cutting, all of the weft wires are removed from the areas between the shortest and longest ends. The portions are fitted together so that the ends of the wires abut. New weft wires, preferably of metal or alternating wires of metal and synthetic plastic, are threaded laterally through the corrugations in the exposed ends. Preferably each of the wires has an angular cross-section, to grip the warp wires. Each wire may be formed with a portion of smaller diameter than the actual weft wire. The portion is first threaded through the ends and the full-size weft wire is then drawn into the fabric. In an alternative embodiment, alternate warp wires of the portions are cut off to short lengths which differ from each other preferably by the length of only one screen aperture and the remainder of the wires have lengths. The weft wires, except for the last weft wire in front of the shortest warp wire end, are removed from the area in which the warp wires have been cut off. Weft wires, preferably those previously removed, are laid into the upwardly open corrugations of the ends of the portion and the ends of the portion are placed over the weft wires and between the ends so that corresponding warp wire ends abut. Small diameter auxiliary weft wires, are first threaded through the open apertures in the warp wire ends and then replaced by normal weft wires or normal weft wires are immediately threaded therethrough. The inserted weft wires may each comprise a thin metal wire core coated with a weldable thermoplastic material. The metal core is heated by an electric current after the weft wires have been positioned so that the plastic coating is fused together with the warp wires.

<CIT> relates to a woven mesh belt for the production of sanitary goods according to the preamble of claim <NUM>.

The object of the present invention is to eliminate the technical problems in the producing line of the water absorbing body. More specifically, the object of the present invention is to prolong the product life of the mesh belt used in the producing line of the water absorbing body, as compared with the conventional product.

In addition, the object of the present invention is to restrict the scattering of the powder material upon the operation of the producing line by preventing the scattered powder material from being stuck on the transfer roll, etc. to restrain the meandering of the mesh belt.

In order to achieve the above-mentioned objects, there is provided a mesh belt according to claim <NUM>.

Advantageous embodiments are defined by the dependent claims.

Here, with respect to the electrically conductive material for the present invention, metal or graphite with an excellent conductivity may be uniformly dispersed into a synthetic fiber, the surface of the metal fiber which is made by metal such as stainless being fiberized, or the one of the organic fiber may be coated with metal, or the surface of the organic fiber may be coated with resin containing the electrically conductive material. For instance, the carbon fiber, metal fiber such as stainless fiber, copper and amorphous alloy, conductive synthetic fiber the surface of which is coated with a conductive polymer, or copper sulfide, or the metal dyeing fiber may be adopted.

In the present invention, at least one of the warps or the wefts constituting the fabric may be made of an electrically conductive material. In addition, all of the warps constituting the fabric may be made of an electrically conductive material, or all of the wefts constituting the fabric may be made of an electrically conductive material. Further, a plurality of the warps of the wefts may be made of an electrically conductive material.

In addition, the mesh belt used in the apparatus for producing the water absorbing body of the present invention is used in the process for producing the water absorbing body. It is normally the fabric processed in an endless type. It can be used in any process, so long as the fabric is used in the process for producing the water absorbing body. For instance, the mesh belt of the present invention can be used in the fabric for transporting, or the fabric for drying.

Still further, any layered structure in the mesh belt of the present invention can be adopted. For instance, one or two multi-layered structure of the fabric is within the scope of the present invention.

By making a portion of, or all of the warps constituting the transporting side of the fabric contacting the material of the water absorbing body, made of an electrically conductive material, the negative charge born on the surface of the fabric due to the contact, etc. can be discharged to the atmosphere from the surface of the fabric, or it can be discharged to the ground via the apparatus for producing the fabric. As a result, the repulse between the material which bears the negative charge such as a high molecule absorbing polymer contained in the water absorbing body can be restricted.

By adopting the above structure, the static electricity generated on the mesh belt can be discharged to the ground via the wefts made of the above-described electrically conductive material, while it can be discharged to atmosphere at the folding back portion of the belt via the roll, so that the negative charge on the transporting side of the fibric contacting the material of the water absorbing body can be efficiently removed.

The warp density is defined according to the following equation: <MAT>.

The warp density is the special equation which the present inventor devised in order to indicate the denseness degrees of the diameter of the warp emerging on its cross section in a case where the fabric is vertically cut along its longitudinal direction.

The diameter of the warp is the one of one single warp, the mesh is defined to be the number of the longitudinal yarns arranged within one inch. In addition, the number [<NUM>] is what one inch is converted into millimeters. For instance, in a case where the diameter of the warp is <NUM>, the number of longitudinal yarns per <NUM> (<NUM> inch) is <NUM>, (<NUM>×<NUM>/<NUM>)×<NUM>=<NUM>%.

The warp density for the mesh belt of the present invention is between <NUM>% and <NUM>%.

The lowest value of the ideal warp density is above <NUM>%. If the highest value of the ideal warp density is below <NUM>%, the technical problem of the clogging, etc. can be restricted, so that the product life can be largely prolonged, as compared with the conventional product, in case of below <NUM>%.

Further, since the rigidity of the mesh belt can be increased by setting the warp density to be within the above numerical range, the extension of the mesh belt can be restricted, so that the slippage can be prevented.

In a case where the warp density of the present invention is <NUM>%, the warps are closely arranged without a space between the adjacent warps. In a case where the warp density of the present invention exceeds <NUM>%, the structure of the warps is multi-layered structure.

According to the mesh belt used in the apparatus for producing the water absorbing body of the present invention, the technical problems in the producing line of the water absorbing body were eliminated, so that the product life of the mesh belt used in the producing line of the water absorbing body was prolonged, as compared with the conventional product.

In addition, according to the mesh belt used in the apparatus for producing the water absorbing body of the present invention, the scattering of the powder material upon the operation of the producing line was restricted by preventing the scattered powder material from being stuck on the transfer roll, etc. to restrain the meandering of the mesh belt.

<FIG> is a conceptual view showing an apparatus for producing a diaper according to the embodiment <NUM> of the present invention.

Now, one example of the embodiment of the mesh belt used in the apparatus for producing the water absorbing body according to the present invention will be described below. Since the following embodiment is a mere example of the present invention, any embodiment which is not explicitly described below can be within the scope of the present invention.

The mesh belt of this embodiment used in the apparatus for producing the water absorbing body is constituted at least by warps and the wefts being woven with each other. The mesh belt of this embodiment may be constituted by a single weaving, one and a half weaving, a double weaving, two and a half weaving, a triple weaving, three and a half weaving, etc. In addition, no particular limitation is put on the fabric structure, so that a plain weaving, or a twill weaving may be adopted. Further, no particular limitation is put on the number of the shafts.

With respect to the electrically conductive material for the present invention, carbon fiber may be adopted.

In particular, the carbon fiber is preferable for the electrically conductive material for the present invention. Since the flexibility can be readily added to the carbon fiber, the workability of the carbon fiber is excellent, so that the carbon fiber can be easily woven with the plastic wire or the metal wire. In addition, the electrical resistance of the carbon fiber is low, so that it is highly electrically conductive, and thus, the negative charge on the surface of the fiber can be efficiently removed. RER( TORAY Co. ), RET( TORAY Co. ), CN225(SHAKESPEARE),etc. can be enumerated.

No particular limitation is imposed on a material for the yarn to be used in the warps and wefts other than the electrically conductive material in the fabric of the present invention, and such material may be selected, in accordance with the application. Examples of it include, in addition to monofilaments, multifilaments, spun yarns, finished yarns subjected to crimping or bulking such as so-called textured yarn, bulky yarn and stretch yarn, and yarns obtained by intertwining them. As the cross-section of the yarn, not only circular form but also square or short form such as stellar form, or elliptical or hollow form can be used. The material of the yarn can be selected freely and usable examples of it include polyester, polyamide, polyphenylene sulfide, polyvinylidene fluoride, polypropylene, aramid, polyether ketone, polyethylene naphthalate, polytetrafluoroethylene, cotton, wool and metal. Of course, yarns obtained using copolymers or incorporating or mixing the above-described material with a substance selected depending on the intended purpose may be used.

Embodiments <NUM>,<NUM> of the present invention will now be explained about as follows.

The mesh belt used in the apparatus for producing the water absorbing body of the Embodiment <NUM> of the present invention is a fabric of a single woven type which is constituted by warps and wefts being woven with each other by means of the plain weaving.

The warps are constituted by <NUM> shafts under a complete structure, and two of sixteen warps are made of a carbon fiber, that is, an electrically conductive material. In addition, the fabric of this embodiment includes eight wefts under a complete structure, and two of eight wefts are made of a carbon fiber, that is, an electrically conductive material. Other warps and wefts are constituted by a mono-filament made of polyester. In the mesh belt of the Embodiment <NUM> of the present invention, the diameter of the warp is <NUM>, the number of the meshes is <NUM>, and the warp density is <NUM>%. Further, the fabric of the Embodiment <NUM> of the present invention is formed into an endless type as a belt for transporting the water absorbing body.

In the mesh belt used in the apparatus for producing the water absorbing body of the Embodiment <NUM> of the present invention, a negative charge under an electrostatic state generated due to the contact between the material can be removed, in a case where the material for the water absorbing body rested on the surface of the fabric ( which is constituted by the pulp fiber and a high molecule absorbing polymer, in this embodiment) is rested on the transporting belt in the producing apparatus. In other words, in the warps contacting the water absorbing body which is made of the above-described electrically conductive material, the negative charge can be discharged to the atmosphere mainly via the folding back portion of the belt. In addition, the wefts made of the above-described electrically conductive material can be electrically discharged to the ground via the side surface portion of the producing apparatus, so that the negative charge on the side contacting the water absorbing body where the fabric is transported can be removed.

By the above mechanism, the scattering of the powder material of the water absorbing body can be prevented upon the operation of the producing line, so that the scattered powder material can be prevented from being stuck on the transfer roll, etc., and thus, the meandering of the mesh belt can be restricted.

The mesh belt used in the apparatus for producing the water absorbing body of the Embodiment <NUM> of the present invention is a fabric of a single woven type which is constituted by warps and wefts being woven with each other.

The warps are constituted by <NUM> shafts under a complete structure, and one fourth of it is woven in a twill weaving. The warps are constituted by a mono-filament made of polypropylene. In addition, the fabric of this embodiment includes eight wefts under a complete structure, and one of eight wefts are made of a carbon fiber, that is, an electrically conductive material. Other wefts are constituted by a mono-filament made of polyester. In the mesh belt of the Embodiment <NUM> of the present invention, the diameter of the warp is <NUM>, the number of the meshes is <NUM>, and the warp density is <NUM>%. Further, the fabric of the Embodiment <NUM> of the present invention is formed into an endless type as a belt for transporting the water absorbing body.

In the mesh belt used in the apparatus for producing the water absorbing body of the Embodiment <NUM> of the present invention, a negative charge under an electrostatic state generated due to the contact between the material can be removed, in a case where the pulp fiber and a high molecule absorbing polymer rested on the surface of the fabric is used with being rested on the transporting belt in the producing apparatus. In other words, the wefts made of the above-described electrically conductive material can be electrically discharged to the ground via the side surface portion of the producing apparatus, so that the negative charge on the side contacting the water absorbing body where the fabric is transported can be removed.

The mesh belt used in the apparatus for producing the water absorbing body of the Embodiment <NUM> of the present invention is a fabric of a double woven type which is constituted by warps and wefts being woven with each other by means of the plain weaving.

The warps are constituted by <NUM> shafts under a complete structure, and are constituted by a mono-filament made of polyester. The wefts are constituted by eight wefts on an upper surface side and four wefts on a lower surface side under a complete structure. In addition, the warps are constituted by eight warps on an upper surface side and four warps on a lower surface side under a complete structure. Further, in this embodiment, two of eight wefts on the upper surface side are made of a carbon fiber, that is, an electrically conductive material. Two of eight warps on the upper surface side are made of a carbon fiber, that is, an electrically conductive material. In the mesh belt of the Embodiment <NUM> of the present invention, the diameter of the warp is <NUM>, the number of the meshes is <NUM>, and the warp density is <NUM>%. Further, the fabric of the Embodiment <NUM> of the present invention is formed into an endless type as a belt for transporting the water absorbing body.

<FIG> is a conceptual drawing showing the apparatus for producing the diaper of the Embodiment <NUM>. The apparatus for producing the diaper of the Embodiment <NUM> will now be explained about, with reference to <FIG>.

As shown in <FIG>, the apparatus <NUM> for producing the diaper of the Embodiment <NUM> includes an apparatus <NUM> for producing the water absorbing body, a process <NUM> for laminating sheets, a process <NUM> for compressing sheets, a process <NUM> for cutting sheets, a process <NUM> for folding sheets, and a process <NUM> for inspecting product.

In the apparatus <NUM> for producing the water absorbing body, water proof sheets forming the surface of the diaper are fed between the feeding rolls <NUM>, <NUM> from the apparatus <NUM> for unwinding water proof sheets to be rested on the mesh belt <NUM> in the apparatus <NUM> for producing the water absorbing body. Cotton-like pulp made of paper is sprayed toward the water proof sheets to be transported on the mesh belt <NUM> by an apparatus <NUM> for spraying cotton-like pulp. Further, polymer which functions to absorb urine and hardens it into jelly form is sprayed toward the water proof sheets to be transported on the mesh belt <NUM> by an apparatus <NUM> for spraying high molecule water absorbing body. In such a case, the mesh belt <NUM> in an endless form is rotated in the direction as shown in an arrow via the folding back roll <NUM>, and the tension rolls <NUM>,<NUM>,<NUM>.

Next, the water proof sheet on which the water absorbing body is rested is transported to the mesh belt used in the process <NUM> for laminating sheets. More specifically, the water absorbing sheet is fed between the feeding rolls <NUM>, <NUM> from the unwinding device <NUM> for the water absorbing sheet, and the water absorbing body is laminated so as to be sandwiched between the water proof sheet and the water absorbing sheet. Next, the surface sheet is fed between the feeding rolls <NUM>, <NUM> from the unwinding device <NUM> for the surface sheet, and the water absorbing sheet and the surface sheet are laminated. Next, in order to form a three-dimensional gather which prevent urine which has been once absorbed from returning back, the sheet is fed between the feeding rolls <NUM>,<NUM> from an apparatus for mounting the gather sheet, and the three-dimensional gather is mounted o the surface sheet. In such a case, the mesh belt is rotated in the direction as shown by an arrow via the feeding roll <NUM>, the folding back roll <NUM>, and tension rolls <NUM>, <NUM>,<NUM>.

Next, the laminated member constituted by a plurality of sheet being laminated is transported to the mesh belt used in the process <NUM> for compressing sheets. The laminated member is transported between the press roll and a support roll to be shaped into a diaper in a compressing manner. In such a case, the mesh belt is rotated in the direction as shown by an arrow via the feeding roll <NUM>, the folding back roll <NUM>, and tension rolls <NUM>,<NUM>.

Next, the laminated member rested on the mesh belt is transported to the process <NUM> for cutting sheets including the cutting device, to be cut into a diaper one by one. Next, the cut diaper is formed into a commercial product via the process <NUM> for folding sheets, and the diaper as a final product is completed via the process <NUM> for inspecting the product through the mech belt. In such a case, the mesh belt is rotated in the direction as shown by an arrow via the feeding roll <NUM>, the folding back roll <NUM>, and tension rolls <NUM>,<NUM>,<NUM>.

Claim 1:
A mesh belt used in a process for producing a water absorbing body, wherein said water absorbing body is a sanitary goods in which a water absorbing property is required, the mesh belt being
formed by warps and wefts being woven with each other, one or more yarns which constitutes the warps and/or the wefts emerging on at least a transporting surface side of the mesh belt is made of an electrically conductive material,
characterized in that
the warp density for the mesh belt defined by the following equation is between <NUM>% and <NUM>%, wherein the warp density (%) = [the diameter of the warp ×the number of meshes (the number of warps per <NUM> (1inch))/<NUM>] ×<NUM>,
wherein the warps and/or wefts made of an electrically conductive material are made of carbon fiber.