JPH06158498A - Production of nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain a method for readily obtaining nonwoven fabric, excellent in process passableness in a process to the formation of a web such as a carding step and capable of being readily split and fibrillated in a process for making a high-pressure fluid stream act and assuming soft hand. CONSTITUTION:The nonwoven fabric is prepared by a method for using splittable conjugate fiber composed of mutually incompatible components, carding the fiber, making a high-pressure fluid stream act thereon, carrying out splitting, fibrillating and fiber interlacing. In the method, the conjugate fiber having 3.0-7.0 ratio of the area of the incompatible contact part to the surface area of the conjugate fiber is used. When the area ratio is >=3.0 to <=7.0, the splitting and fibrillating are hardly caused under the stress applied to the time for forming the web. Thereby, the card passableness is good. On the other hand, the splitting and fibrillating under the stress acting by the high-pressure liquid stream are sufficiently advanced to provide the nonwoven fabric assuming soft hand.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a non-woven fabric having a soft texture. More specifically, the present invention relates to a method capable of efficiently producing a nonwoven fabric made of ultrafine fibers using splittable conjugate fibers.

[0002]

2. Description of the Related Art Generally, it is well known that a non-woven fabric using fine fibers has a soft texture, and various proposals have been made as a method for obtaining such ultra fine fibers. The most useful method is solubility (solvent or acid,
There is a method in which sea-island type fibers are formed by two or more kinds of polymers having different alkali solutions), and sea components are dissolved and removed to form ultrafine fibers. However, in such a method, a solvent treatment step and a solvent recovery step are required, and there are drawbacks that the process becomes complicated, and the cost is disadvantageous.

As another method, composite fibers composed of polymers having no affinity for each other, for example, polyester / polyamide, polyester / polyolefin, polyamide / polyolefin, etc., are subjected to mechanical impact such as puffing, needle punching, high-pressure water treatment and the like. A method of forming ultrafine fibers by the method described above is proposed in JP-A-62-133164 and JP-A-62-268861.

However, since the composite fiber obtained by such a method has a poor affinity between polymers, component cracks are produced when mechanical crimping is applied or when a web is formed by passing through a card process, and thus produced. However, there is a problem that the property significantly decreases.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and its purpose is to make it difficult to form divided fibrils until a web is formed in a mechanical crimping step, a card step, etc. It is an object of the present invention to provide a method for producing a nonwoven fabric exhibiting a soft texture, which can easily achieve split fibrillation and random entanglement of single fibers when a high-pressure fluid flow is applied to form the nonwoven fabric.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that mechanical crimping is imparted by increasing the ratio of the contact area between components to the surface area of splittable conjugate fiber. The stress per unit area acting on the composite interface at the time of card passage or at the time of passing through the card is reduced, and as a result, the process passability up to web formation is improved. The inventors have found that the same can be achieved as in the past, and have reached the present invention.

That is, according to the present invention, a splittable conjugate fiber composed of mutually incompatible components, at least one of which is divided into multiple layers by the remaining components, is made into a web with a card, By injecting a high-pressure liquid flow, in a method for producing a nonwoven fabric which causes split fibrillation of fibers and performs random entanglement to form an integral structure, the composite fiber satisfies the following conditions: Manufacturing method, 3.0 ≦ R ≦ 7.0 (where R represents the ratio S ₁ / S ₀ of the surface area S _{0 of the} composite fiber and the total contact area S ₁ of mutually incompatible components). Provided.

The present invention will be described in detail below. As a specific example of the cross section of the splittable conjugate fiber in the present invention, as shown in FIG. 1, for example, two kinds (component A, component B) or more incompatible thermoplastic polymers having no mutual adhesiveness are used. It refers to a cross-sectional shape in which coalescing components are alternately arranged, but is not limited to this as long as it can be divided into a plurality of fibrils.

In the present invention, the splittable conjugate fiber described above has a ratio (R = S ₁ / S ₀ ) of the total contact area S ₁ of the mutually incompatible components to the surface area S ₀ thereof.
The greatest feature is that it is 3.0 or more and 7.0 or less,
Particularly, it is preferably 4.0 or more and 6.0 or less. When the area ratio R is in this range, split fibrillation does not proceed at the stress level acting on the composite fiber when mechanical crimping is given by indentation crimping or the like and when passing through the card, resulting in good card passing property. Is obtained. On the other hand, during the treatment with the high-pressure liquid flow, the stress acting on the composite fiber is sufficiently large so that it can be split into fibrils as in the conventional case, and the random entanglement between the fibers is also achieved to provide a soft texture. A non-woven fabric is obtained.

On the other hand, when R is less than 3.0,
The contact areas of the components which are incompatible with each other are too small, the stress per unit area of contact acting on the composite fiber increases, the split fibrils are easily formed, and the card passing property is deteriorated. On the other hand, when it exceeds 7.0, the contact area of the incompatible component becomes too large, the efficiency at the time of jetting a high-pressure fluid flow to form fibers into split fibrils decreases, and the flexibility of the resulting nonwoven fabric is reduced. Is decreased, which is not preferable.

In the present invention, the combination of two thermoplastic polymer components which are incompatible with each other means, for example, polyester and polypropylene, polyester and nylon, nylon and polypropylene.

The splittable conjugate fiber used in the present invention is obtained by bundling unstretched composite spun yarns by a method known in Japanese Patent Publication No. 39-29636 and Japanese Patent Laid-Open No. 50-5650, stretching them, and then mechanically winding them. It can be obtained by adhering an oil agent while imparting crimp and cutting it into finite fiber lengths to form short fibers. In order to obtain the nonwoven fabric of the present invention, it is preferable to heat the splittable conjugate fiber by an appropriate method such as wet heat or dry heat so that the boiling water area shrinkage rate is 20% or less.

The thickness of the splittable conjugate fiber is about 1 to 20 denier, and the denier of the split fibrillated single fiber composed of at least one component formed by split fibrillation is preferably 0.5 denier or less. More preferably, it is 0.3 denier or less, and if it exceeds 0.5 denier, it becomes hard to the touch, and loses its suitability as a base fabric for artificial leather and a cover stock material for sanitary materials.

The number of crimps of the splittable conjugate fiber is preferably in the range of 5 to 25 per inch. When the number of crimps is less than 5 / inch, the entanglement between the fibers becomes weak and the compression recovery property also deteriorates. On the other hand, if it exceeds 25 per inch, it becomes difficult to open the fiber, and the bulk of the web becomes small.

The fiber length of the splittable composite short fibers is 15 to 80 mm.
Is preferred. If the fiber length is less than 15 mm, the web obtained during carding will be cut and the handling will be poor.
On the other hand, if the fiber length exceeds 80 mm, process troubles such as nep will occur and it will be difficult to obtain a uniform web.

In the present invention, after the split type composite short fibers are formed into a web by a card by a conventional method, the split type composite short fibers in the web ascending the card are further promoted to form split fibrils and are randomly entangled. To cause
The high pressure liquid stream impinges on the web surface.

The liquid used as the liquid stream is water or hot water.
Is desirable because it is easy to handle. In addition,
The diameter of the hole is 0.05 to 1.0 mm, preferably 0.1 to
0.4 mm, injection pressure 100-200 kg / cm²so
Yes, the distance between the injection hole and the web is preferably 1 to 15 cm
If the distance becomes wider, the jet flow and air will mix.
The division confounding effect becomes small. In this way the non-woven eye
10 to 300 g / m ²If it is in the range, soft wind
The base cloth for artificial leather and cover stock for sanitary materials
A non-woven fabric useful as a material can be manufactured.

[0018]

As described in detail above, in the method for producing a non-woven fabric of the present invention, the ratio of the total area where the incompatible components are contact-bonded to the composite fiber surface area is 3.0.
Since the above composite fibers are used, the stress applied to the composite fibers in the process of applying a mechanical crimp such as an indentation crimp applying device, the process of forming a web by carding, etc. It is presumed that this is because the stress per unit area is dispersed due to the dispersion on the contact surface, the split fibril formation of the composite fiber does not proceed, and a good quality web can be stably obtained.

On the other hand, since the upper limit of the same area ratio is 7.0, the load stress per unit contact area when a high-speed liquid flow such as a pressure of 100 kg / cm ² or more can be sufficiently increased, and split fibrillation and random fibrillation can be performed. The entanglement can be performed in the same manner as in the past.

[0020]

Therefore, according to the present invention, it is possible to efficiently produce a web by using splittable conjugate fibers, efficiently split fibers and randomly entangle fibers by using a high-speed liquid flow. The non-woven fabric is characterized by exhibiting a soft texture and having excellent properties as a sanitary material such as a base fabric for artificial leather and a cover stock material.

[0021]

The present invention will be described in more detail with reference to the following examples.

Polyethylene terephthalate as component A and nylon 6 as component B were melt-composite spun at a weight ratio of 1: 1 and wound at 1000 m / min.
A split-type composite undrawn yarn having a cross section similar to that shown in FIG. The unstretched yarns are aligned and roller-stretched 3.5 times at a stretching temperature of 90 ° C., and 18 threads / in a crimping machine.
After applying a mechanical crimp of 25 mm, it was heat treated at 130 ° C. for 30 minutes and then cut into a length of 51 mm to obtain a short fiber having a single fiber fineness of 3 denier. The obtained short fibers were made into a web having a basis weight of 40 g / m ² with a roller card at a speed of 60 m / min. At this stage, split fibril formation of the fibers was hardly observed, and the card passing property was also very good.

Next, a pressure of 120 kg / cm is applied from a group of injection nozzles in which holes having a diameter of 0.1 mm are arranged in a row at a pitch of 0.6 mm.
Using a device in which a columnar water stream is sprayed at ² , after repeating the above web three times to form split fibrils and entangle,
It was dried with hot air at 130 ° C. for 20 minutes. When the obtained sheet was observed with a microscope, 95% or more of the splittable conjugate fibers were peeled and split in the nonwoven fabric according to the present invention, and exhibited an extremely soft texture.

[0024]

[Table 1]

[Brief description of drawings]

FIG. 1 shows an example of a cross-sectional view of a splittable conjugate fiber used in the present invention.

FIG. 2 shows an example (R is less than 3) of a cross section of a splittable conjugate fiber outside the present invention.

FIG. 3 shows an example of a cross section of a splittable conjugate fiber outside the present invention (R exceeds 7).

Claims (1)

[Claims] 1. A web of splittable conjugate fibers composed of mutually incompatible components, at least one of which is divided into multiple layers by the rest of the components, and then jetted with a high-pressure liquid stream. Thus, in the method for producing a non-woven fabric in which the fibers are split into fibrils and are randomly entangled to form an integral structure, the composite fiber satisfies the following conditions. 3.0 ≦ R ≦ 7.0 (In the formula, R represents the ratio S ₁ / S ₀ of the surface area S _{0 of the} composite fiber and the total contact area S ₁ of mutually incompatible components)