JP2763056B2 - Method for producing composite nonwoven sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention is composed of a bicomponent composite filament, one component is a filament, the other component is amorphous, and a filament is formed inside the irregularly formed part. The present invention relates to a method for producing a composite nonwoven sheet in which components are present.

(Prior Art) Nonwoven fabrics made of long fibers are often used in places where strength is required because they are often superior in strength to short fiber nonwoven fabrics. However, not only on the powerful side,
There are many functional demands depending on the application, and in many cases, these non-woven fabrics alone cannot be achieved to satisfy these requirements. In such a case, the non-woven fabric is combined with other materials. Often respond to.

When a nonwoven fabric requires ventilation performance close to that of a film,
This is one of the things that can be achieved by the combination. In other words, it is desired to give the nonwoven fabric a film-like smoothness, while keeping the properties of the nonwoven fabric, that is, the tear properties, tensile strength, appropriate air permeability, and the like.

These requirements cannot be met by the conventional long-fiber nonwoven fabric alone, and in many cases, these requirements have been met by compounding. For example, a laminate in which a thermoplastic resin film is bonded to one or both sides of a long-fiber nonwoven fabric, and a resin processed product in which a resin is deposited on a nonwoven fabric are known.

(Problems to be Solved by the Invention) However, a conventional composite nonwoven sheet is manufactured by laminating a long-fiber nonwoven fabric with a sheet-like material such as a film or by depositing a liquid resin solution prepared on a long-fiber nonwoven fabric. Method, the complex process is complicated, and
The obtained sheet-like material also has a problem that the resin cannot be uniformly deposited on the entire nonwoven fabric when the sheet is easily peeled from the bonded portion or when the sheet is thick.

Although the present invention is a two-component composite nonwoven sheet, its manufacturing process is simple, there is no separation between the two components, it has a film-like smoothness, low air permeability, and it has a nonwoven fabric. An object of the present invention is to provide a method for producing a composite composite nonwoven sheet having characteristics, that is, tear strength and tensile strength.

(Means for Solving the Problems) The present inventors have made intensive studies to solve such problems, and as a result, have reached the present invention. That is, the present invention relates to a web comprising a two-component composite filament having a core-sheath structure comprising a thermoplastic resin A and a thermoplastic resin B having a melting point higher than that of the resin A, wherein the A component covers the entire surface of the B component. Is entirely heat-pressed at a temperature equal to or lower than the melting point of the component A, and the component A of the filament constituting the web is softened and melted, and the polymer is caused to flow, so that only the component A is applied over the entire surface of the web. The gist of the present invention is to provide a method for producing a composite nonwoven sheet, which is characterized in that the sheet is made amorphous and the sheet surface is provided with a film-like form.

As the thermoplastic resin used in the present invention, usually, polyethylene, polypropylene,
Polyamide, polyester, etc. can be used. In particular, when polyethylene is used for component A and polyethylene terephthalate is used for component B, the difference in melting point is 100%.
℃ or more, and the melting point difference between the two is large, so that the allowable range of the thermal welding conditions described later is large, and the polystyrene itself, which is the irregular component of the two-component composite nonwoven sheet, has a moderate softness. Very good results are obtained.

The bicomponent composite filament used in the present invention can be produced using a conventionally known composite spinning apparatus. The weight ratio of the low melting point component A to the high melting point component B is to be determined according to the purpose of use of the composite nonwoven sheet, which is a finally obtained product, and is not particularly limited. That is, when the component A is large, the obtained nonwoven sheet has a large amount of indefinite formation, and is a sheet having little or no air permeability. On the other hand, when the amount of the component A is small, the sheet has a small amount of irregular shapes and a high air permeability.

In addition, the fineness of the bicomponent composite filaments should also be determined according to the intended use of the nonwoven sheet that will be the final product. That is, the fineness of the entire bicomponent composite filament is determined by the fineness of the component B remaining in the nonwoven sheet while maintaining the fiber shape and the weight ratio of the component A and the component B described above.
Mechanical properties such as strength are to be determined.

As described above, in the two-component composite filament of the present invention, the weight ratio and the fineness of the component A and the component B are not limited at all, but the fineness is considered in consideration of the productivity. The weight ratio of the component A to the component B is preferably 1 to 20 denier, and the weight ratio of the component A is preferably in the range of 0.2 to 10. It is preferable to select an appropriate one in the above range according to the purpose of use of the final product.

The two-component composite filament in the present invention is
When the entire surface is heat-welded after forming the web, the low melting point component A that deforms or melts needs to be distributed almost uniformly over the entire surface of the web. Therefore, a two-component composite filament having a so-called core-sheath structure having a shape in which the component A wraps the component B everywhere is used.

The above-mentioned core-sheath structure generally has a cross-sectional shape in which the inner layer portion and the outer layer portion are substantially concentric. However, the so-called multi-core structure has two or more core components in one fiber. There may be. The cross-sectional shape does not necessarily have to be circular. However, if it is stated that, particularly, the A component of the outer layer is deformed by thermal pressure welding, so considering productivity, etc., at least the outer layer has a deformed cross section. You don't have to.

In the present invention, since the component A is deformed or melted by hot pressing, it is not necessary that all filaments constituting the web have a two-component composite structure. Even if a fiber consisting of the component A alone is included, it is only necessary that continuous filaments exist inside the low-melting amorphous sheet.

As described above, the effect of the present invention can be most exhibited when all the filaments constituting the web have a two-component composite core-sheath structure, but as described above, the present invention is not necessarily limited to this. If the B component is distributed over the entire surface of the sheet in the form of a filament, the same effect can be expected.

Next, in the present invention, a conventionally known technique is also used for a method of depositing the spun fibers and forming a web.
In other words, a method is generally used in which the spun two-component composite filament is stretched by utilizing the air thickness, and is transported while being deposited on the moving mesh. However, the deposition and web formation in the present invention is not particularly limited to the above-described method, and the fiber is maintained over a whole surface in a state where the fiber can be substantially regarded as a continuous filament and without a significant deviation in the direction of the fiber. What is necessary is just to be able to deposit substantially uniformly.

Further, for the sake of continuous production, for example, for the purpose of transporting the web, the deposited web is partially hot-pressed and fixed before it is entirely hot-pressed, or entangled with the web by needle punching. There is no particular limitation on the application of heat or partial entanglement with a needle punch after being thermally pressed.

The entire surface thermal welding in the present invention is intended to soften or partially melt the low melting point component of the two-component composite filament constituting the web and to make the web into an irregular shape. Become restricted.

First, it is essential that the thermal pressure welding method be a method in which pressure is applied to the web substantially uniformly and entirely. More specifically, it is a calendar device comprising a pair of flat rolls and the like. There is no particular limitation on the material of the roll, but usually, heating and pressurization are performed simultaneously with this calendar device, so that a combination of metal / metal or a combination of metal / heat-resistant elastic material is generally used. There is no limitation on repeating the thermal pressing process a plurality of times for the purpose of performing the thermal pressing uniformly over the entire surface.

In addition, since the A component must be deformed, the heat welding temperature must be at least the glass transition temperature of the A component, and the upper limit must be lower than the melting point of the A component. There is. When hot pressing is performed at a temperature equal to or higher than the melting point of the component A, the melted component A is fused to the hot pressing device, and the contamination of the roller increases, resulting in a production problem. Here, the melting point is a temperature indicating the maximum endothermic amount when the temperature and the calorific value are measured while raising the temperature with a differential scanning calorimeter.

Since the upper limit of the thermal welding temperature is controlled mainly by the production problem that the component A is fused to the thermal welding device, it has a close relationship with the processing speed, and is not determined only by the temperature. Absent. When the processing speed is low, the possibility of fusion to the thermal welding apparatus is increased even at a lower temperature, while when the processing speed is high, the possibility of fusion at a higher temperature is reduced. However, in any case, the possibility of fusion is extremely high when the members are hot-pressed at a temperature higher than the melting point of the component A. Therefore, the present invention is not performed under a temperature condition exceeding the melting point of the component A.

For this reason, the heat welding temperature should be determined by the performance of the target product and cannot be determined unconditionally, but it is usually a temperature about 20 ° C lower than the melting point of component A. Is good.

(Function) According to the present invention, the difference between the melting points of the two-component thermoplastic resin is used to make only the low-melting-point component amorphous, but the high-melting-point component is hardly subjected to thermal deformation. Demonstrates the performance of composite nonwoven sheet as a film,
It is possible to obtain a nonwoven sheet having a performance in which the high-melting-point component exhibits the performance as a nonwoven fabric, which cannot be realized by a conventional one-component nonwoven fabric alone.

In addition, many of the conventional two-component nonwoven sheets only expected to function only as an adhesive component with respect to the low-melting point component, whereas the method for producing a composite nonwoven sheet of the present invention provided a low-melting point. In addition to the function of the component as an adhesive component, a nonwoven sheet having the performance of a conventional composite laminated sheet having the performance of a sheet film, that is, the performance of smoothness and low air permeability, is obtained.

Furthermore, unlike the composite sheet conventionally used for the same purpose, it does not require a step of bonding a nonwoven fabric to a film or impregnating the nonwoven fabric with a resin. Sheets are formed by heat-welding the entire surface, thereby eliminating the drawbacks of the composite sheet such as peeling of the bonded part and uneven adhesion of resin.

(Example) The present invention will be specifically described by way of an example. The measurement methods measured in this example are summarized below.

(1) Tensile strength A 3 cm wide and 30 cm long sample was tested at a test length of 20 cm for 1 minute at 100% elongation speed using a constant speed elongation type tensile tester, and the stress at cutting was measured. .

(2) Air permeability The air permeability was measured according to the JIS L-1096A method.

(3) Melting point of polymer The melting point of polyethylene was defined as the temperature at which the maximum value of the melting endothermic peak was measured at a heating rate of 20 ° C./min using a DSC-2 differential scanning calorimeter manufactured by Perkin Elmer.

(4) Intrinsic viscosity The intrinsic particle size of polyethylene terephthalate is determined by using a mixed solvent of phenol and titanium tetrachloride of equal weight composition,
The measurement was performed under the conditions of 0.5 g / 100 ml and measurement temperature of 20 ° C.

As a core component Pollet Chi terephthamide regulator of Example 1 intrinsic viscosity 0.70, density ^{0.973g / cm 3, ASTM-D} -1238 melt index is 25 g / 10 min according to (E), straight-melting point of 128 ° C. A two-component core-sheath structure with a chain low-density polyethylene as the sheath component. A filament with a single fiber fineness of 3.0 denier and a composite ratio (weight ratio) of the core component and the sheath component of 1: 1 is spun and immediately drawn by air pressure. After the fiber was spread by an opening device, the web was produced by depositing the material on a moving porous strip. This web
The whole was hot-pressed by a heat-pressing device consisting of a pair of flat rolls heated to 110 ° C to obtain a nonwoven sheet having a basis weight of 40 g / m ² .

The obtained non-woven sheet has a vertical tensile strength of 10.8 kg / c.
m, air permeability was ^2.5 cc / cm ² / sec, thickness was 62 μm, and air permeability was low while maintaining strength.

Example 2 The same polyethylene terephthalate and polyethylene as in Example 1 were used, with the same core-sheath structure as in Example 1 and a single yarn fineness of 5.
A filament having a denier of 0 and a composite ratio (weight ratio) of a core component and a sheath component of 1: 3 was spun to obtain a nonwoven sheet having a basis weight of 70 g according to Example 1.

The obtained nonwoven sheet has a vertical tensile strength of 18.5 kg / 3.
cm, the air permeability was 1.0 cc / cm ² / sec or less, and the thickness was 118 μm.

Comparative Example 1 The same filament as in Example 1 was spun and formed into a web, and the area ratio of the press contact portion was 15% and the density of the press contacts was 22 pieces.
using a hot-pressing device consisting of an engraving roll and a flat roll with a dot pattern of / cm ² and partially hot-pressing at 110 ° C.
A nonwoven sheet having a basis weight of 40 g was obtained.

The obtained nonwoven sheet has a vertical tensile strength of 9.9 kg / c.
m, air permeability is 230 cc / cm ² / sec, thickness is 210 μm, irregularities are large on the non-woven fabric surface, air permeability is high,
Since it has only the performance of a non-woven fabric as it is, it is necessary to bond a film or apply a resin to obtain a smooth surface and low air permeability.

(Effects of the Invention) According to the present invention, a fiber having a composite structure is spun in advance, and only the low melting point component is made amorphous after being formed into a sheet. A composite non-woven sheet that combines the performance of a film and the performance of a non-woven fabric in one process without the need for laminating a non-fibrous sheet with a non-fibrous sheet.
In addition, the obtained sheet is a problem in the case of a laminated product.
The components do not exfoliate or separate.

Claims (2)

(57) [Claims] 1. A web comprising a two-component composite filament having a core-sheath structure comprising a thermoplastic resin A and a thermoplastic resin B having a melting point higher than that of the resin A, wherein the A component covers the entire surface of the B component. The entire surface is hot-pressed at a temperature equal to or lower than the melting point of the component A, and the component A of the filaments constituting the web is softened and melted, and the polymer is flown so that only the component A is immobilized over the entire surface of the web. A method for producing a composite nonwoven sheet, comprising shaping the sheet into a film-like form on the sheet surface. 2. The method according to claim 1, wherein the component A is polyethylene and the component B is polyethylene terephthalate.