JP3000553B2 - Nonwoven fabric and method for producing the same - Google Patents

Description

The present invention relates to a nonwoven fabric composed of ultrafine fibers,
Particularly, it relates to a nonwoven fabric suitable for a wiping material.

[Prior Art] Conventionally, non-woven fabrics using ultrafine fibers formed from splittable conjugate fibers have been developed as base fabrics for artificial leather, for example, Japanese Patent Publication No. 52-30628 and Japanese Patent Publication No. 52-30629.
And JP-B-53-37456. These non-woven fabrics have a structure in which fiber bundles are entangled to imitate the structure of natural leather, and are usually formed by forming a non-woven fabric containing splittable composite fibers and then dividing the fibers by heat treatment or chemical treatment. Manufactured.

By the way, recently, such nonwoven fabrics have come to be used for applications such as wiping materials due to their high wiping properties due to their large surface area. That is, the nonwoven fabric is composed of ultrafine fibers formed by division, and since the bonding of the fibers is mainly performed only by the entanglement between the fibers, the fiber surface area is smaller than when using other bonding means. Large, high garbage collection power.

However, such a structure is liable to be deformed by an external force, and in particular, fibers may come off or pills may occur on the surface of the nonwoven fabric. When used as a base cloth for artificial leather, the surface is coated with resin, so such a drawback is not a problem.However, in the case of a wiping material, it is a major problem since it is used by being rubbed with an object to be cleaned. Was.

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned drawbacks of the related art, and has an object to provide a nonwoven fabric having a large surface area and excellent surface resistance.

[Means for Solving the Problems] That is, the present invention provides a nonwoven fabric formed by splitting splittable conjugate fibers and / or a bundle of the ultrafine fibers, wherein the ultrafine fibers are subjected to a hydroentanglement treatment. Are entangled with each other, and there are two or more types of ultrafine fibers having different melting points in the ultrafine fibers.
The present invention relates to a nonwoven fabric having a plurality of recesses formed by heat bonding only ultrafine fibers having a low melting point.

As the splittable conjugate fiber used in the present invention, a conjugate fiber made of a resin having two or more components having different melting points and divided into ultrafine fibers by mechanical impact or chemical treatment is suitably used. As a combination of resins constituting the splittable conjugate fiber,
It is desirable to use different peeling properties or solvent solubility, for example, a combination of polyamide resin and polyester resin, polyamide resin and polyolefin resin, polyester resin and polyolefin resin, polyester resin and polyacrylonitrile resin and the like are suitable. I have. In particular, the combination of polyester resin and polyamide resin,
The composite spinning process and the stretching process are easy, and the separation can be easily performed by the impact force of the high-pressure water flow. Here, an example of a combination of two components has been described, but three or more components may be combined. Also,
The difference in melting points of the resins to be combined is desirably at least 20 ° C., and when three or more components are combined, the difference in melting points between the resin having the highest melting point and the resin having the lowest melting point is preferably 20 ° C. or more.

Examples of the splittable conjugate fiber as described above include, for example, a chrysanthemum flower-shaped fiber in which one component is radially arranged between other components, a sea-island fiber having a cross-section in which another component is dispersed in an island shape in one component, and different components alternately. Fibers having various cross-sectional shapes, such as bimetallic fibers having a cross-section laminated in layers, can be used.

In forming a fibrous web such as a carding process, if the fibers are too fine, the yield is reduced. Therefore, the fineness of the splittable conjugate fiber before splitting is preferably in the range of 1 to 5 denier, Is roughly fine
It is desirable to be in the range of 0.05 to 0.5 denier. The cross-sectional shape of the divided ultrafine fibers has various shapes such as a circle, an ellipse, a crescent, a triangle, a rectangle, a sector, and an arrowhead, but in the case of a nonwoven fabric used for a wiping cloth or the like,
It is preferable to select one having a cross-sectional shape that increases the surface area of the fiber.

The splittable conjugate fiber is formed into a fibrous web by a known fibrous web forming method such as a carding method, an air lay method, a wet method, and a spun bond method. This fiber web must be mainly composed of splittable conjugate fibers,
It is desirable that at least 50% by weight or more, preferably 70% by weight or more of the splittable conjugate fiber is contained. Further, a plurality of fiber webs may be laminated, and in this case, it is preferable to laminate fiber webs having different fiber orientations.
For example, a unidirectional fiber web laminated with a cross lay web or a non-directional fiber web whose fiber orientation crosses,
A nonwoven fabric having strength in any direction can be manufactured.

Next, the fiber web is subjected to a splitting process of splittable conjugate fibers. As a method of splitting the splittable conjugate fiber, for example, a method of treating with a solvent that dissolves only one of the resin components constituting the split fiber, or utilizing a difference in heat shrinkage of the resin component forming the split fiber There are a dividing method and a dividing method by applying a mechanical impact such as a water entanglement process or a needle punch. Of these, the method of splitting the fibers by water entanglement is particularly desirable because the fibers can be entangled at the same time as the splitting, so that the steps can be omitted. In this case, it is preferable to select a splittable conjugate fiber that is easily split by a mechanical impact. The ultrafine fibers divided by the mechanical impact are partially present in bundles, partially branched from the bundle, and partially released from the bundle. The ultrafine fibers are classified into those made of a resin having a relatively high melting point and those made of a resin having a low melting point.

The fibers split as described above are entangled by a hydroentanglement treatment. The water entanglement process, for example, by blowing a high-pressure water flow from a plurality of nozzles at a pressure of 15 to 100 kg / cm ² ,
This is done by acting on the fibrous web. Since the divided fibers are very fine and many, the fibers are entangled densely by the hydroentanglement, and the obtained nonwoven fabric has a large surface area. If splitting of the splittable conjugate fiber and entanglement of the fiber are performed simultaneously in this water entanglement step, after the splitting process, the strength is higher than that of the entangled fiber, and the orientation of the original fiber is higher. Was saved.

Thereafter, a concave portion is formed on at least one surface of the nonwoven fabric by hot embossing or the like. Heat embossing is to heat the nonwoven fabric to a certain temperature, and then to preheat embossing that passes between the engraving roll and flat roll having a predetermined uneven pattern, or to heat at least one of the rolls to a certain temperature, and put the nonwoven fabric between the rolls. Through which heating embossing is performed. At this time, the residual heat or heating temperature is set to be equal to or higher than the softening point of the low melting point resin and lower than the melting point of the high melting point resin among the resins constituting the splittable conjugate fiber. In other words, among the ultrafine fibers formed by dividing the splittable conjugate fiber, those formed of a resin having a low melting point function as adhesive fibers, and those formed of a resin having a high melting point are substantially subjected to this heat treatment. No change will occur. Further, as the concavo-convex pattern of the engraving roll, generally, a pattern in which convex portions having a predetermined shape selected from a circle, a quadrangle, a triangle, a polygon, and the like are distributed in an appropriate arrangement is used. On the surface of the nonwoven fabric in contact with the convex portion of the engraving roll, the fiber web is compressed and the low melting point resin is thermally bonded to form a concave portion. The proportion of the recesses on the nonwoven fabric surface is desirably in the range of 5 to 30%. If it exceeds 30%, the hand of the nonwoven fabric becomes hard, while if it is less than 5%, one of the objects of the present invention is the surface. Improves resistance.

The nonwoven fabric obtained in this way has a structure in which ultrafine fibers are highly entangled, so the surface area is very large,
The strength is excellent, and since the concave portion is formed by the thermal bonding of the ultrafine fibers made of a low melting point resin, the fibers do not come off and are hardly worn. In addition, the presence of the concave portion also has a function of facilitating scraping of dust when the nonwoven fabric is used for an application such as a wiping cloth.

[Example] (Example 1) A unidirectional fiber web 15 g / m ² made of a splittable conjugate fiber having a chrysanthemum-shaped cross section made of a polyester resin and a nylon resin (trade name: Berima X, manufactured by Kanebo Co., Ltd.) A cross lay web 60 g / m ² composed of the same split fibers was laminated.

Next, a high-pressure water stream blown from a plurality of nozzles under the condition of a water pressure of 45 to 90 kg / cm ² was first applied to the laminated web from the side of the unidirectional fiber web. , The split fibers were split and at the same time the fibers were entangled to obtain a nonwoven fabric with a basis weight of 75 g / m ² . When the surface of the obtained nonwoven fabric was observed with a microscope from the side where the unidirectional fiber web was laminated, there were a plurality of fiber bundles composed of microfibers oriented in one direction substantially in parallel,
Other fiber bundles or fibers are entangled so as to bridge between the fiber bundles to form a lattice-like pattern.

This nonwoven fabric was passed through an embossing roll composed of a combination of an engraving roll and a smooth roll having an arrangement pattern in which a plurality of rectangular protrusions were arranged vertically and horizontally, and subjected to heating embossing. At this time, the temperature of the engraving roll was set to 220 ° C. The ratio of the total area of the concave portions formed in the nonwoven fabric to the surface of the nonwoven fabric was about 20%.

The obtained nonwoven fabric was measured for 5% modulus, tensile strength, tensile elongation, and washing resistance according to JIS L-1096, and abrasion resistance was measured according to JIS L-1048.

(Comparative Example 1) A nonwoven fabric was obtained in exactly the same manner as in Example 1 except that embossing was not performed.

The obtained nonwoven fabric was measured for 5% modulus, tensile strength, tensile elongation, and washing resistance according to JIS L-1096, and abrasion resistance was measured according to JIS L-1048.

(Example 2) 18 g / unidirectional fiber web composed of 50% splittable conjugate fiber (Berima X manufactured by Kanebo Co., Ltd.) having a chrysanthemum-shaped cross section made of polyester resin and nylon resin and 50% rayon fiber and m ^2, and by laminating a cross-laid web 67 g / m ² made of the same fiber blend.

Next, a high-pressure water stream blown from a plurality of nozzles under the condition of a water pressure of 50 to 95 kg / cm ² was first applied to the laminated web from the side of the unidirectional fiber web. And splitting the split fibers and simultaneously entangled the fibers to obtain a nonwoven fabric with a basis weight of 85 g / m ² .

This nonwoven fabric was passed through an embossing roll composed of a combination of an engraving roll and a smooth roll having an array pattern in which a plurality of diamond-shaped convex portions were arranged vertically and horizontally, and subjected to heat embossing. At this time, the temperature of the engraving roll is 220 ° C
Set to. The ratio of the total area of the recesses formed in the nonwoven fabric to the surface of the nonwoven fabric was about 28%.

The obtained nonwoven fabric was measured for 5% modulus, tensile strength, tensile elongation, and washing resistance according to JIS L-1096, and abrasion resistance was measured according to JIS L-1048.

(Comparative Example 2) A nonwoven fabric was obtained in exactly the same manner as in Example 2 except that embossing was not performed.

The obtained nonwoven fabric was measured for 5% modulus, tensile strength, tensile elongation, and washing resistance according to JIS L-1096, and abrasion resistance was measured according to JIS L-1048.

[Effects of the Invention] Since the nonwoven fabric of the present invention has the above-described configuration, the following effects can be obtained.

Since the concave portion is formed on the surface of the nonwoven fabric, the effect of scraping and collecting dust can be expected, and the wiping property is improved.

Since the concave portions are formed by adhesion of ultrafine fibers made of a low melting point resin, the surface strength of the nonwoven fabric is high.

For this reason, when used as a wiping material,
Even when the wiping operation is performed, the surface is hardly roughened and the fluff is not easily removed, and the service life is prolonged.

In addition, since the surface does not become rough even after washing,
It can be used repeatedly by washing.

Further, the ultrafine fibers made of a high melting point resin are not substantially deformed in the above-mentioned bonding, so that the surface area can be maintained large and the wiping property does not decrease. For example, when all of the constituent fibers are thermally bonded in the concave portions, the surface portion of the nonwoven fabric that comes into contact with the roll naturally undergoes some thermal deformation and the portion that turns into a film increases, and the surface area significantly decreases. Ultrafine fibers made of a high melting point resin do not undergo such deformation and have a large surface area.

In addition, since the embossing is performed after the water entanglement is performed, the substantial strength of the nonwoven fabric is covered by the water entanglement. It is soft.

There is a design effect because a pattern is generated by the distribution of the concave portions.

In particular, in the nonwoven fabric manufacturing method, when the division and the entanglement of the fibers are performed simultaneously with a high-pressure water stream, the process can be rationalized, and after the division treatment, the orientation of the original fibers is higher than that of the entangled fibers. A high-strength nonwoven fabric with preserved properties is obtained.

As described above, the nonwoven fabric of the present invention has an excellent function and is extremely suitable as a wiping material.

Claims (3)

(57) [Claims] An ultrafine fiber formed by splitting splittable conjugate fibers and / or a nonwoven fabric in which bundles of ultrafine fibers are entangled, wherein the ultrafine fibers are entangled by a hydroentanglement treatment, In addition, two or more types of ultrafine fibers having different melting points exist in the ultrafine fibers, and among the ultrafine fibers, only a low-melting ultrafine fiber has a plurality of concave portions formed by heat bonding. Non-woven fabric. 2. The nonwoven fabric according to claim 1, wherein the ratio of the total area of the concave portions to the surface of the nonwoven fabric is 5 to 30%. 3. A method comprising two or more resins having different melting points,
A high-pressure water stream is applied to a fiber web mainly composed of splittable conjugate fibers that are split into microfibers by mechanical impact to split the splittable conjugate fibers and entangle the fibers, and then soften a resin having a low melting point. A method for producing a nonwoven fabric, comprising: performing heat embossing at a temperature equal to or higher than a point and lower than the melting point of a resin having a high melting point, and thermally bonding only ultrafine fibers made of a resin having a low melting point to form a concave portion.