Patent Description:
More specifically, the present invention is related to the industrial fabric which is capable of making a manufacturing machine of the nonwoven fabric to operate at a higher speed, and of preventing generation of wrinkles or the rolling back of the web which conspicuously occurs in a case where a light nonwoven fabric is manufactured.

Conventionally, it has been generally prevalent that after a fiber assembly is fed on an endless running industrial fabric, the nonwoven fabric is formed while the fiber assembly (referred to as " web" hereinafter) is transported. Many kinds of methods of manufacturing the nonwoven fabric are widely known, and new technology for manufacturing the nonwoven fabric has been developed one after another.

Such being the case, it is difficult to clearly classify the types for manufacturing the nonwoven fabric. If the types for manufacturing the nonwoven fabric is classified, in view of the method of bonding the fibers, one type in which the fibers with low melting point is adopted as web, other type in which a composite fiber of core-sheath type covering the resin with low melting point is used, and still another type ( thermal bonding method) in which web formed by powders with low melting point being mixed is fed to the industrial fabric, and the fibers with low melting point is melted by heating or by ultra-sonic welder to generate the welding of the portions between the fibers to form into the non-woven fiber are known. In addition, a resin bond method in which the web is fed to the industrial fabric, and adhesive resin is contained and dried to form the nonwoven fabric. Further, a chemical bonding method, a spun race method in which the fibers are entangled by water stream with high pressure.

On the other hand, if the method of manufacturing the nonwoven fabric, in view of the method of feeding the web, a carding method in which the web is fed using the carding machine, an air laid method in which the defibrate fibers is fed using air, and a spun bonding method in which the fibers spun into yarns from the fiber material is directly fed to the industrial fibers without using the fibers formed in advance, and the portions between the fibers is welded by heating, etc. are known as a method of using dry fibers. In addition, a melting blow method in which the fibers are spun like mist to fed to the industrial fabric.

Now, the industrial fabric is concretely explained below. The Patent publications <NUM> and <NUM> are exemplified as prior art of the industrial fabric.

In the industrial fabric used in the spun bonding method and the melting blow method, raw material for the nonwoven fabric is arranged in parallel or indefinitely on the front surface of the industrial fabric to form the web, and the nonwoven fabric is manufactured by the portions between the fibers being welded by heating, etc.. In such a case, since the nonwoven fabric to be manufactured is light, and, in the method of manufacturing the nonwoven fabric at a high speed in recent years, in particular, the web is caused to float due to the air stream generated around the web, so that technical troubles in which wrinkles are partially generated, or the end portion can be caused to roll back when the web is transported can arise.

<FIG> is a view showing a process of manufacturing the nonwoven fabric of a spun-bond type. As shown in <FIG>, material from a hopper <NUM> is mixed, welded and stirred, etc. by an extruder <NUM>, and an amount of melted material is extruded from a spin opening <NUM> by a gear pump <NUM> to be formed into long fibers. Then, the long fibers are exposed to cool wind to be fiberized by the ejector <NUM>, and captured on the endless industrial fabric <NUM> which is suspended on guide rolls <NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM> to be rotated, whereby the web is formed by the fact that air is suck from the underside of the industrial fabric <NUM>.

The web is pressurized and bonded by the heated compaction roll <NUM> and the calendar roll <NUM> to be formed into a nonwoven fabric SB in a sheet form, and raw nonwoven fabric in a roll form is formed by a winding apparatus <NUM>.

The nonwoven fabric SB is a nonwoven fabric with long fibers, so that it is used for a variety of applications, such as a hygiene material such as diapers, sanitary products, life material, vehicle material, construction material, and agricultural material.

In addition, in recent years, since SB is comparatively thin and light, the roll back and the wrinkle problem can conspicuously arise, due to the speed up of the manufacturing apparatus.

In particular, a part, an end, of all of the web can float after it passes the compaction roll <NUM>.

In addition, if the wrinkles are generated on the nonwoven fabric in a span-bond type, the quality of the final product can be deteriorated.

The present inventor devised to process the industrial fabric used in the process of manufacturing the nonwoven fabric in order to prevent the floating of the web, the generation of the rolling back or the wrinkles. More specifically, the present inventor carried out the method of coating the surface of the industrial fabric with resin. As a result, although the problem of the rolling back, etc. of the non-nonwoven fabric rested on the industrial fabric is temporarily solved, it was found out that the resin was peeled off from the surface having irregularities of the industrial fabric with time, so that the above effect was not lasted. In addition, the resin peeled off from the industrial fabric was mixed with the nonwoven fabric to be manufactured, so that the quality or the yield of the nonwoven fabric was deteriorated. Next, the present inventor carried out a method of surface roughening by polishing the surface of the industrial fabric. As a result, it was found out that burr formed on the surface of the industrial fabric by the polishing was peeled off along with resin with time, or worn out due to the friction between the burr and the raw material, so that the effect derived from such burr turns out not to last. Further, the problems of reproducibility and workability were arisen.

<CIT> relates to a dryer and/or industrial fabric with a silicone-coated surface. An industrial fabric having improved sheet restraint and wear resistance along with acceptable permeability. The improvement is effected by coating only the high spots of the fabric with silicone material. The coating methods used in this invention may include kiss roll coating, gravure roll coating, rotogravure printing, rotary screen coating, screen-printing and/or flexography. The improvement is also applicable to corrugator fabrics.

<CIT> relates to a method to reduce forming fabric edge curl. A method for reducing or eliminating forming fabric edge curl includes slitting or scoring the knuckles formed by cross-machine direction yarns on the long-shute knuckle side of a papermaker's forming fabric. The knuckles are scored or slit to a depth no greater than half the diameter of the cross-machine direction yarns. At least one such slit or score is provided per knuckle. The scoring or slitting has the effect of bringing the ratio between the shrink forces acting on the two sides of the forming fabric in the cross-machine direction closer to unity, and, in turn, reduces or eliminates the edge curl resulting from shrinkage in the cross-machine direction.

The object of the present invention is to provide an industrial fabric which is capable of preventing the roll back or the floating of the web, and the wrinkles on the surface of the nonwoven fabric from being generated when the nonwoven fabric is manufactured.

The object of the present invention is to provide an industrial fabric which is capable of maintaining the rigidity as the industrial fabric, while at the same time, of preventing the roll back or the floating of the web, and the wrinkles from being generated for a long time during the web forming process.

The object of the present invention is to provide an industrial fabric which is capable of attaining a suitable gripping performance so as to smoothly remove the web without enhancing the adhesiveness to the web (referred to as "gripping performance" hereinafter) more than necessary when the web is transferred from the web forming process to the next process.

In order to achieve the above-mentioned object, there is provided an industrial fabric according to claim <NUM>. In addition, there is provided a method according to claim <NUM>. Advantageous embodiments are defined by the dependent claims.

The industrial fabric of the present invention includes following technical features in order to solve the above technical problems.

In an industrial fabric formed by warps and wefts being woven with each other, at least an emboss pattern with at least one embossing design is formed near an apex of a knuckle portion emerging on a front surface side in said warps and/or said wefts, wherein the emboss patterns are lateral stripe patterns.

The technical feature of the present invention is that at least an emboss pattern with an embossing design being regular and/or irregular is formed near an apex of a knuckle portion emerging on a front surface side in said warps and/or said wefts. For example, if embossing designs are formed on a portion other than the knuckle portion emerging on a front surface side in said warps and/or said wefts, the gripping performance becomes too much, so that the web cannot be smoothly removed when the web is transferred to the next process. The present invention solves such a problem. In other words, in the present invention, the web is gripped only when necessary, and the web can be smoothly transferred to the next process.

Here, the emboss pattern with embossing designs means the pattern with embossing designs is formed on the surface of the warps and/or the wefts. More specifically, in a plan view is a lateral stripe pattern.

Said warps and/or said wefts in which said emboss pattern with irregularities is formed can be made of plastic mono-filament.

Since the tension force is applied on the industrial fabric in the warp direction, the yarn of the industrial fabric of the present invention is preferred to be made of mono-filament.

With respect to plastic mono-filament forming the industrial fabric of the present invention, usable examples of it include polyester, polyamide, polyphenylene sulfide, polyvinylidene fluoride, polypropylene, aramid, polyether ketone, polyethylene naphtha late, and polytetrafluoroethylene. 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. In addition, with respect to plastic mono-filament forming the industrial fabric of the present invention, yarns with core-sheath structure in which material for layer portion is different from that for the inside can be used.

As the cross-section of the yarn, not only circular form but also square or short form such as stellar form, or elliptical form can be used.

The industrial fabric can be constituted by a fabric used in the manufacturing of nonwoven fabric which is arranged in a parallel or in a non-parallel manner, and a portion between fibers of which is welded.

The cutting depth of said emboss pattern can be formed between <NUM>% and <NUM>% of a diameter of said warps and/or said wefts.

The cutting depth of the emboss pattern can be set to be <NUM>~<NUM>% of the diameter of the yarn. If the cutting depth of the emboss pattern is below <NUM>% of the diameter of the yarn, the gripping performance is low, while If the cutting depth of the emboss pattern is above <NUM>% of the diameter of the yarn, the strength of the yarn is weak, and the technical problem that the web cannot be smoothly removed when it is transferred to the next process due to the too strong gripping performance of the nonwoven fabric can arise. In particular, the cutting depth of the emboss pattern is preferred to be set to be <NUM>~<NUM>% of the diameter of the yarn.

When the industrial fabric is manufactured, the direction in which the lower coefficient of static friction of the industrial fabric is low among the results of measuring the grip property in the forward direction or reverse direction should be aligned with the traveling direction in which the industrial fabric is advanced in the nonwoven fabric manufacturing machine, the floating of the web can be prevented during the web forming process, so that the smooth transfer of the web to the next process can be realized.

The cross sectional shape of said warps and/or said wefts can be a circle, a rectangle such as a quadrangle, a polygon such as a star, or an ellipse.

The invention further relates to a method of manufacturing an industrial fabric, said method comprises a step of weaving warps and wefts, and a step of forming at least an emboss pattern with embossing designs near an apex of a knuckle portion emerging on a front surface side in said warps and/or said wefts by means of thermal emboss process, wherein the emboss patterns are lateral stripe patterns.

Said warps and/or said wefts in which said emboss pattern with embossing designs is formed are made of plastic mono-filament, the process of forming said emboss pattern by said thermal emboss process is carried out under a temperature between a glass transition point of plastic mono-filament and a melting point of plastic mono-filament, and a pressure between <NUM> MPa (<NUM>/cm) and <NUM> MPA (<NUM>/cm).

An explanation is made about a case where the material of the plastic mono-filament is polyethylene terephthalate below as an example.

The glass transition point and the melting point of polyethylene terephthalate are <NUM> and <NUM>. In a case where the temperature condition is below the glass transition point, the embossing design shape cannot be sufficiently formed on the surface of the industrial fabric, since the softening of the plastic mono-filament is insufficient. On the other hand, the temperature condition exceeds the melting point, the plastic mono-filament is caused to be welded, so that the configuration of the industrial fabric cannot be maintained. From the standpoint of the above, the temperature condition is more preferred to be set to be <NUM>~<NUM>. In particular, the temperature condition is more preferred to be set to be <NUM>~<NUM>.

In addition, in the present invention, the process is preferred to be carried out under the pressure condition of <NUM> Mpa~<NUM> MPa (<NUM>~<NUM>/cm). If the pressure condition is below <NUM>,<NUM> MPa (<NUM>/cm), the embossing designs cannot be sufficiently formed on the surface of the industrial fabric. On the other hand, if the pressure condition exceeds <NUM> MPa (<NUM>/cm), the thickness of the industrial fabric becomes thinned due to the excess process. Further, the mesh is collapsed, so that the air permeability is lowered. From the standpoint of the above, the pressure condition is more preferred to be set to be <NUM>~<NUM>/cm. In particular, the pressure condition is more preferred to be set to be <NUM> MPa~<NUM> MPa (<NUM>~<NUM>/cm).

The cutting depth of said emboss pattern can be formed between <NUM>% and <NUM>% of a diameter of said warps and/or said wefts in the step of forming said emboss pattern.

By adopting the industrial fabric according to the present invention, the roll back or the floating of the web, and the wrinkles on the surface of the nonwoven fabric can be prevented from being generated when the nonwoven fabric is manufactured.

By adopting the industrial fabric according to the present invention, the rigidity as the industrial fabric can be maintained, while at the same time, the roll back or the floating of the web, and the wrinkles can be prevented from being generated for a long time during the web forming process.

By adopting the industrial fabric according to the present invention, a suitable gripping performance so as to smoothly remove the web without enhancing the adhesiveness to the web more than necessary can be attained when the web is transferred from the web forming process to the next process.

Now, the structure and the effect of the fabric of the present invention will be described below. Embodiments of the fabric of the present invention will be described thereafter with reference to the drawings. In this connection, since the embodiment is just an example of the present invention, the embodiment which is not described hereinafter can be encompassed by the scope of the present invention.

As shown in <FIG>, the industrial fabric <NUM> of the Embodiment <NUM> of the present invention is the one formed by the warps <NUM> and the wefts <NUM> being woven with each other. Emboss concave patterns <NUM> are formed on only an portion T near an apex of the knuckle portions emerging on the front surface side of the warps <NUM>. Such emboss patterns <NUM> are formed in lateral stripes.

By forming the emboss patterns <NUM>, the web can be prevented from floating due to the fact that the abutting surface of the nonwoven fabric is caught in the emboss patterns <NUM>, even if the web is rested on the industrial fabric <NUM>. As a result, the wrinkles can be prevented from generating on the front surface of the web. In addition, the end portion of the nonwoven fabric can be prevented from rolling back. Further, when the web is transferred from the web forming process to the next process, the web can be smoothly transferred to the next process, since the abutting surface of the nonwoven fabric is not caused to be caught in the emboss patterns <NUM> more than necessary.

In this connection, the warps and the wefts in the industrial fabric in the first embodiment are made of polyethylene terephthalate.

With respect to the method of forming the emboss patterns in the industrial fabric in the First Embodiment, the industrial fabric is pressed against the emboss roll with convex portions. The pressing process is effected under the temperature of <NUM>, and the pressure of <NUM> MPa (<NUM>/cm).

Under such conditions, the emboss patterns with the cutting depth of <NUM>%~<NUM>% in the lateral stripes can be formed by pressing the industrial fabric against the emboss roll with the convex portions.

Second Embodiment (not according to the invention).

As shown in <FIG>, the industrial fabric <NUM> of the second embodiment of the present invention is the one formed by the warps <NUM> and the wefts <NUM> being woven with each other. Emboss concave patterns or embossing design patterns <NUM> are formed on only a portion T near an apex of the knuckle portions emerging on the front surface side of the warps <NUM>. Such emboss patterns <NUM> are formed in oblique cross patterns.

By forming the emboss patterns <NUM>, the web can be prevented from floating, even if the web is rested on the industrial fabric <NUM>. As a result, the wrinkles can be prevented from generating on the front surface of the web. In addition, the end portion of the nonwoven fabric can be prevented from rolling back. Further, when the web is transferred from the web forming process to the next process, the web can be smoothly transferred to the next process, since the abutting surface of the nonwoven fabric is not caused to be caught in the emboss patterns <NUM> more than necessary.

In this connection, the warps and the wefts in the industrial fabric in the second embodiment are made of polyamide.

Third Embodiment (not according to the invention).

shown in <FIG>, the industrial fabric <NUM> of the third embodiment of the present invention is the one formed by the warps <NUM> and the wefts <NUM> being woven with each other. Emboss concave patterns or embossing design pattern <NUM> are formed on only a portion T near an apex of the knuckle portions emerging on the front surface side of the warps <NUM>. Such emboss patterns <NUM> are formed in patterns in each of which circles are arranged in a zigzag.

By forming the emboss patterns <NUM>, the web can be prevented from floating, even if the web is rested on the industrial fabric <NUM>. As a result, the wrinkles can be prevented from generating on the front surface of the web. In addition, the end portion of the nonwoven fabric can be prevented from rolling back. Further, when the web is transferred from the web forming process to the next process, the web can be smoothly transferred to the next process, since the abutting surface of the nonwoven fabric is not caused to be caught in the emboss patterns 27more than necessary.

In this connection, the warps and the wefts in the industrial fabric in the third embodiment are made of polyvinylidene fluoride.

Fourth Embodiment (not according to the invention).

As shown in <FIG>, the industrial fabric <NUM> of the fourth embodiment of the present invention is the one formed by the warps <NUM> and the wefts <NUM> being woven with each other. Emboss concave patterns or embossing design patterns <NUM> are formed on only a portion T near an apex of the knuckle portions emerging on the front surface side of the warps <NUM>.

Such emboss patterns <NUM> are formed in oblique cross patterns.

In this connection, the warps <NUM> and the wefts <NUM> in the industrial fabric <NUM> in the fourth embodiment are made of polyethylene terephthalate and carbon yarns of core-sheath structure.

As shown in <FIG>, the industrial fabric of the fifth embodiment of the present invention is the one formed by the warps <NUM> and the wefts <NUM> being woven with each other. Emboss concave patterns or embossing design patterns <NUM> are formed on only a portion T near an apex of the knuckle portions emerging on the front surface side of the warps <NUM>. Such emboss patterns <NUM> are formed in concave manner.

By forming the emboss patterns <NUM>, the web can be prevented from floating, even if the web is rested on the industrial fabric. As a result, the wrinkles can be prevented from generating on the front surface of the web. In addition, the end portion of the nonwoven fabric can be prevented from rolling back. Further, when the web is transferred from the web forming process to the next process, the web can be smoothly transferred to the next process, since the abutting surface of the nonwoven fabric is not caused to be caught in the emboss patterns <NUM> more than necessary.

In this connection, the warps <NUM> and the wefts <NUM> in the industrial fabric in the fifth embodiment are made of polyethylene terephthalate.

The emboss pattern of the industrial fabric of each of the embodiments <NUM> to <NUM> is a circular zigzag pattern in which the circles are arranged in a zigzag, the embodiments <NUM> to <NUM> is a lateral stripe pattern. In this connection, the emboss process is not applied to the industrial fabric of the reference example.

The following feeding speed, temperature, and pressure are the process conditions, in a case where the emboss patterns are formed on an apex of the knuckle portion emerging on the front surface side of the manufactured warps means of emboss processing.

The temperature is set between <NUM>°Cand <NUM>, the pressure is set between <NUM> MPa (<NUM>/cm) and <NUM> MPa (<NUM>/cm), and the feeding speed is set between <NUM>/min and <NUM>/min. The process conditions in each of the embodiments are set in Table <NUM>.

In the warps, there are yarns made of polyethylene terephthalate and yarns made of carbon with core-sheath structure. The diameter of the warp is <NUM>, and the cutting depth of the hounds tooth pattern in polyethylene terephthalate is about <NUM> (its ratio to diameter is <NUM>%), while the cutting depth of the carbon yarns is about <NUM> (its ratio to diameter is <NUM>%).

On the other hand, the cutting depth of the lateral stripe in polyethylene terephthalate is about <NUM> (its ratio to diameter is <NUM>%), while the cutting depth of the carbon yarns is about <NUM> (its ratio to diameter is <NUM>%).

As clearly seen from Tables <NUM> and <NUM>, as compared with the reference example, a certain gripping performance was caused in the industrial fabric in each of the embodiments. The industrial fabric in each of the embodiments <NUM> -<NUM> conspicuously attained the preferred gripping performance. The emboss pattern or embossing design patterns formed in the embodiments <NUM> -<NUM> was a lateral stripe pattern.

With respect to the industrial fabric in the embodiment <NUM>, the air permeability and the gripping performance (the forward and the reverse directions : the unit is "N" ("kgf') were excellent, the decreasing rate of the fabric thickness to the reference example was <NUM>%. The industrial fabric with a little decreasing rate of the fabric thickness is evaluated to be a good product.

With respect to the industrial fabric in the embodiments <NUM>~<NUM>, the gripping performance, etc. was inferior to the industrial fabric in the embodiments <NUM>~<NUM>. In particular, the air permeability in the embodiment <NUM> was low. In addition, the gripping performance (the forward direction) was low in the embodiments <NUM>~<NUM>. Further, the gripping performance (the reverse direction) was also low in the embodiments <NUM>~<NUM>. The decreasing rate of the fabric thickness was bad in the embodiment <NUM>, in particular.

Still further, in a case where these industrial fabrics were used in the nonwoven fabric manufacturing machine, the floating of the web, the rolling back or the wrinkles of the web was not caused. No special technical problem was not arisen when the web was transferred from the web forming process to the next process.

In the following table <NUM>, the pressure is converted as follows: <NUM>/cm<NUM> corresponds to <NUM> MPa; <NUM>/cm<NUM> corresponds to <NUM> MPa; <NUM>/cm<NUM> corresponds to <NUM> MPa and <NUM>/cm<NUM> corresponds to <NUM> MPa.

Claim 1:
An industrial fabric formed by warps (<NUM>; <NUM>) and wefts (<NUM>; <NUM>) being woven with each other, characterized in that emboss patterns (<NUM>; <NUM>) with irregularities are formed on an apex and near the apex of a knuckle portion emerging on a front surface side in said warps and/or said wefts, wherein the emboss patterns (<NUM>; <NUM>) are lateral stripe patterns.