JPH0759786B2 - Olefin-based composite filament non-woven sheet and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is composed of two components, one component is filamentous, the other component is amorphous, and filamentous form is present inside the amorphous part. The present invention relates to existing olefin-based composite non-woven sheets and a method for producing the same.

(Prior Art) Nonwoven fabrics made of long fibers are superior in strength to short fiber nonwoven fabrics, and are therefore widely used in fields that take advantage of this feature. However, recent non-woven fabrics are required not only to have a strong surface but also to pursue various functionalities depending on the application, and to satisfy these requirements, non-woven fabrics alone cannot be achieved. In many cases, this is often addressed by combining non-woven fabrics with other materials. For example, even when a non-woven fabric is required to have ventilation performance close to that of a film, this is one of the things that can be achieved by combining these. In other words, in order to satisfy both the film-like smoothness of the non-woven fabric and the fabric performance such as the tearing property, the tensile strength and the appropriate air permeability, it is not possible to achieve it by the conventional long fiber woven non-woven fabric alone. We have responded to these demands by compounding. For example, there are known a laminated product in which a thermoplastic resin film is attached to one side or both sides of a long fiber non-woven fabric, or a resin processed product obtained by depositing a resin on the non-woven fabric.

(Problems to be Solved by the Invention) However, in the above-mentioned composite non-woven sheet, the production is performed by laminating a long-fiber non-woven fabric and a sheet-like material such as a film or by depositing a resin liquid prepared in a liquid state on the long-fiber non-woven fabric. Since it is created by the method, the compounding process is complicated and
The obtained sheet-like material also has a problem that it is easily peeled from the bonded portion, or in the case of a thick sheet, the resin cannot be uniformly deposited on the entire nonwoven fabric.

The object of the present invention is a two-component composite filament non-woven sheet, which has a simple manufacturing process, has no peeling between the two components, has film-like smoothness and low air permeability, and is a non-woven fabric sheet. It is an object of the present invention to provide a composite filament nonwoven sheet having properties such as tear strength and tensile strength, and a method for producing the same.

(Means for Solving the Problems) The inventors of the present invention have arrived at the present invention as a result of earnest studies for solving such problems.

That is, in the present invention, the blend structure (C) obtained by mixing polyethylene (A) and polypropylene (B ₁ ) is the first component, and the same polypropylene (B ₂ ) as the polypropylene (B ₁ ) is used as the first component. An olefin-based composite filament non-woven sheet comprising two-component composite filaments having two components, wherein the polyethylene (A), polypropylene (B ₁ ) and polypropylene (B ₂ ) are each of the following conditions (a): ), (B) and (c)
The essence is to provide an olefin-based composite filament non-woven sheet and a method for producing the same.

(I). The polyethylene (A) is flow-indeterminate and distributed over the entire surface of the sheet, (b). The polypropylene (B ₂ ) retains the filament morphology, (C). In the fluidized amorphous polyethylene (A), at least the polypropylene (B ₁ ) and the polypropylene (B ₁ ) and the polypropylene (B ₂ ) are hot-pressed to each other.

The polyethylene (A), polypropylene (B ₁ ) and (B ₂ ) used in the present invention may be ordinary fibers or those used for molding. In the present invention,
The same polypropylene is contained in both the amorphous part and the part that maintains the filament shape.
Therefore, the adhesive force between the fibers constituting the non-woven sheet is excellent. Moreover, the polyethylene itself, which is the amorphous part of the composite non-woven sheet, has appropriate softness. As described above, according to the present invention, a very good result can be obtained because it is a non-woven fabric made of a composite filament made of a blend structure of polyethylene and polypropylene and polypropylene.

The two-component composite filament used in the present invention can be manufactured using a conventionally known composite spinning device.

In the first component of the blend structure (C), mixing polypropylene (B ₁ ) with polyethylene (A) is
When component (B ₁ ) is mixed instead of component (A) alone, spinning can be performed at a higher speed, and filament of fine denier can be spun out, and a nonwoven sheet with a softer texture can be obtained. Because it will be done. However, (B ₁ )
On the contrary, if the mixing amount of the components exceeds 25% by weight, the spinnability becomes poor, and if the mixing amount of the (B ₁ ) component is less than 1% by weight, the spinnability is the same as that of the polyethylene (A) component alone. , (B ₁ ) component is preferably mixed in an amount of 1 to 25% by weight.

The ratio of the first component (C) to the second component (B ₂ ) of the two-component composite filament, that is, the composite ratio (weight fraction), should be determined according to the intended use of the thermocompression-bonded composite filament nonwoven sheet. There is no particular limitation. That is, when the amount of the component (C) is large, the resulting non-woven sheet has a large number of irregular shaped portions and becomes a sheet with little or no air permeability. On the other hand, if the amount of component (C) is small, the amorphous portion is small and the sheet has high air permeability.

In addition, the fineness of the two-component composite filament should be determined according to the purpose of use of the non-woven sheet that will be the final product. That is, since the non-woven sheet of the present invention is composed of a two-component composite filament, the fineness of the (B ₂ ) component that remains while maintaining the filament shape and the (C) component of the (B ₂ ) component described above. The weight ratio determines the performance of the non-woven sheet and determines mechanical properties such as strength.

The non-woven sheet of the present invention solves the problem of easy peeling, which is present in the conventional composite of film and non-woven fabric, and has both the performance as a film and the performance as a non-woven fabric. This is achieved by optimizing the amount of polyethylene in the woven sheet. This means that the weight ratio (B ₁ / A) of the polypropylene (B ₁ ) component to the polyethylene (A) component in the first component (C) of the two-component composite filament is in the range of 1 to 25/99 to 75. , And the weight ratio of the component (C) to the polypropylene (B ₂ ) component (C /
B ₂ ) in the range of 40-80 / 60-20, that is, the polyethylene (A) component in the filament is 30
It is achieved by adjusting the amount to be ~ 79% by weight. (A) component
If it is less than 30% by weight, the peel resistance is not improved, and conversely, if the amount of component (A) exceeds 79% by weight, the fineness of the component (B ₂ ) that remains in the filament sheet while maintaining the filament shape is maintained. It becomes too small and the mechanical properties of the nonwoven sheet become insufficient.

Thus, in the present invention, considering the performance and productivity of the non-woven sheet, the weight ratio (B ₁ / A) of the polypropylene (B ₁ ) component to the polyethylene (A) component in the first component (C) is In the range of 1 to 25/99 to 75, and the weight ratio (C / B ₂ ) of the component (C) to the polypropylene (B ₂ ) component is
The range of 40-80 / 60-20 and the fineness of filament should be within the range of 1-20 denier.

In the composite filament non-woven sheet which is the object of the present invention, 2
It is necessary that the component-based composite filament is heat-pressed over the entire surface after the web is formed, and the polyethylene (A) component that deforms or melts is distributed almost uniformly over the entire surface of the web. Therefore, in the filament, not only the polypropylene (B ₂ ) component but also the blend structure (C) component obtained by mixing the polyethylene (A) component and the polypropylene (B ₁ ) component in the longitudinal direction. it is necessary that the continuous, in particular component (C) (B ₂₎ or the so-called core-sheath structure of enveloped shape components, or (C) the component wraps the (B ₂₎ component However, a so-called side-by-side structure in which both the (C) component and the (B ₂ ) component are continuous is desirable.

The core-sheath structure generally has a cross-sectional shape in which the inner layer portion and the outer layer portion are substantially concentric circles, but it is a so-called multicore structure having two or more core components in one fiber. It may be. The cross-sectional shape does not necessarily have to be circular, but if it is stated, the polyethylene (A) component in the outer layer is indefinite due to thermocompression welding. It is not necessary to have a modified cross section.

In the case of the composite filament nonwoven sheet of the present invention, since the polyethylene (A) in the component (C) is deformed or melted by hot pressing, all filaments constituting the web are necessarily a two-component composite structure. Need not be a fiber having That is, fibers made of polyethylene (A) alone may be contained, and a continuous filament may be present inside the low melting point amorphous sheet material. What is important here is the weight ratio of the polyethylene (A) component in the fibers constituting the non-woven sheet. Considering the composite ratio of the present invention, the two-component composite filament and polyethylene (A) are considered. With respect to the ratio of the fibers composed of a single component, it is preferable that the weight ratio of at least the two-component composite filament is 80% or more. If it is less than 80%, the resulting non-woven sheet cannot obtain a uniform composite structure over the entire surface, and the portion where only the polypropylene (B ₂ ) component is present is reduced, which is the non-woven object of the present invention. I can't get a seat.

As described above, the effect of the present invention can be most effectively exerted when all filaments forming the web have a two-component core-sheath composite structure, but the invention is not necessarily limited to this. ₂ ) If the component is distributed in the filament form over the entire surface of the sheet, the same effect can be expected even if the composite filament has a side-by-side structure.

The reason is that the two-component composite filament constituting the non-woven sheet of the present invention has the blend structure (C) of polyethylene (A) and polypropylene (B ₁ ) as the first component, and in the above-mentioned component (C). This is due to the fact that the same polypropylene (B ₁ ) as in ( ₂ ) is constituted as the second component (B ₂ ). In the non-woven sheet, the state of polypropylene components in polyethylene (A) that has been flow-deformed by full-scale heat pressing is because polypropylene (B ₁ ) and (B ₂ ) are the same thermoplastic resin. Has a high affinity for, for example, in the case of a core-sheath composite filament,
The first part, which is a sheath in the filament that has been heat-pressed
Polypropylene (B ₁ ) in component (C) and second core
A component of the polypropylene (B _2), but also between filaments are bonded to produce self-heating undergoing polypropylene (B ₁₎ between the strong pressure contact stress of the first in the component (C) is the filament sheath Forming part. on the other hand,
In the case of side-by-side type composite filaments, in the heat Pressed filaments is polypropylene of the first in the component (C) (B ₁₎ and the polypropylene of the second component (B _2), and each is between filaments filaments Polypropylene (B ₁ ) in the first component (C) of
Polypropylene of the first in the component (C) (B ₁₎ and the polypropylene of the second component (B _2), but polypropylene of the second component (B ₂₎ each other by bonding as in the case of core-sheath type composite filament Part will be formed. Therefore, each of the obtained unknowable sheets has a strong adhesive force at the interface between the first component and the second component, and therefore has excellent mechanical properties such as tear strength and tensile strength, and is suitable for applications. It also has low air permeability.

Next, as a method of depositing the spun fibers in the present invention and forming a web, a conventionally known technique is used.
That is, a method is generally used in which the spun bicomponent composite fiber is drawn by utilizing air pressure and is transferred while being deposited on a moving mesh body. However, the deposition and web formation in the present invention are not limited to this method, and the fibers can be regarded as substantially continuous filaments, and there is no significant deviation in the direction of the fibers, and almost all over the entire surface. It goes without saying that a method for manufacturing a nonwoven fabric that can be uniformly deposited can also be used.

In addition, for the convenience of continuously producing a non-woven sheet, for example, for the convenience of transferring a web, the deposited web is partially heat-pressed and fixed before the whole is heat-pressed, or a web is formed by needle punching. There is no particular limitation on the entanglement of the web, or the entanglement of the web by the needle punching after the partial hot pressing.

The whole-surface hot-pressing in the present invention is intended to soften or partially melt the low melting point component of the filament having a two-component composite structure constituting the web to make it indefinite, so that the temperature and The pressure welding method will be limited. First, it is essential that the hot-pressing method is a method capable of applying a pressure to the web substantially uniformly and entirely. Specifically, it is a calender device consisting of a pair of flattrols and the like. There is no particular limitation on the material of the roll, but since this calendering device normally heats and pressurizes at the same time,
A metal / metal combination and a metal / heat resistant elastic body combination are common. It should be noted that there is no limitation on repeating the heat-pressure welding process several times for the purpose of performing uniform heat-pressure welding over the entire surface.
The pressure of the heat press contact is adjusted by the linear pressure between the pair of flat rollers, which is the above-mentioned calender device, according to the performance of the intended product. However, in order to maintain the shape of the non-woven sheet, the linear pressure is preferably at least 20 kg / cm, and in order to obtain the sheet of the present invention, the linear pressure is preferably 150 kg / cm or more. This makes it possible to form a portion where polypropylenes are adhered to each other as described above. If the linear pressure is set to 200 kg / cm or more using a multi-stage device, it is possible to obtain a sheet suitable for applications requiring performance as a film. The upper limit of the linear pressure is not particularly limited as long as it does not damage the sheet and maintains uniform smoothness, but it is usually determined by the mechanical specifications of the device as described above. Further, regarding the temperature of the heat-pressure welding, it is necessary to deform the polyethylene (A), so that the temperature of the heat-pressure welding is at least equal to or higher than the glass transition point of the polyethylene (A), and the upper limit is that of the polyethylene (A). It must be below the melting point. When hot pressing is performed at a temperature equal to or higher than the melting point of polyethylene (A), the melted polyethylene (A) is fused to the hot pressing device, and the contamination of the roller increases, which causes a problem in production. In addition,
The melting point referred to here is the temperature indicating the maximum endothermic amount when the temperature and the calorific value are measured while the temperature is being raised by a differential scanning calorimeter. Further, the upper limit of the heat-welding temperature is limited mainly by the production problem that polyethylene (A) is fused to the heat-welding device, so that it is closely related to the processing speed, and only the temperature. It is not decided by. When the processing speed is low, the possibility of fusion bonding to the thermocompression bonding apparatus is higher even at lower temperatures, while when the processing speed is higher, the possibility of fusion bonding at higher temperatures is low. However, in any case, when hot-pressure welding is performed at a temperature higher than the melting point of polyethylene (A), the possibility of fusion becomes extremely high. Therefore, in the present invention, heat-pressure welding is performed at a temperature condition higher than the melting point of polyethylene (A). is not.

For this reason, the heat-welding temperature should be determined by the performance of the intended product and cannot be determined unconditionally, but it is usually 10 to 30 ° C above the melting point of polyethylene (A).
Lower temperatures are preferred.

(Operation) In the present invention, the low melting point component (polyethylene) is utilized by utilizing the difference in the melting points of the thermoplastic resins constituting the two-component composite filament.
However, since the high melting point component (polypropylene) does not undergo the thermal deformation to the extent that it becomes amorphous, the low melting point component exhibits the performance as a non-woven sheet film, and the high melting point component Most of the components exert the performance as a non-woven fabric. Furthermore, since polypropylene, which is the same thermoplastic resin, is contained in both the first component composed of a blend structure of polyethylene and polypropylene and the second component composed of polypropylene, the amorphous part and filament form are retained. Between the
Polypropylene partially adheres between the first component and the second component in the composite filament, the first component and the first component between the composite filaments, and in some cases, the second component and the second component. Integral is obtained from the presence of the cracked portion, which improves the adhesion at the interface between the two composite components.

Further, in the conventional two-component non-woven sheet, the low melting point component was required only to function as an adhesive component for maintaining the shape of the non-woven fabric, whereas in the composite filament non-woven sheet of the present invention, the two-component non-woven sheet Since the same polypropylene is contained in all the components of the system composite filament, it is possible to provide the adhesive function and the film-like function of the sheet, that is, the smoothness and the low air permeability function, in the low melting point component, and the thermal compression bonding When performing, the feature is that a feeling of unity of both the irregular shape portion and the portion that maintains the filament shape can be obtained.

Further, the manufacturing method is not a conventional method of laminating a non-woven fabric and a film or impregnating a non-woven fabric with a resin, but a composite filament non-woven sheet is obtained by heat-bonding a web or sheet made of a two-component composite filament over the entire surface. As a result, the drawbacks of the conventional composite non-woven sheet such as peeling of the bonded portion and uneven adhesion of resin can be eliminated.

(Example) An example demonstrates this invention concretely. The measurement methods used in this example are summarized below.

(1) Tensile strength A sample with a width of 3 cm and a length of 30 cm was tested using a constant-speed elongation type tensile tester with a test length of 20 cm at an elongation rate of 100% for 1 minute to measure the stress during cutting.

(2) Air permeability It was performed according to JIS L-1096A method.

(3) Melting point of polymer The melting point of polyethylene and polypropylene was measured using a Perkin-Elmer DSC2 differential scanning calorimeter.
The temperature showing the maximum value of the melting endothermic peak measured at 20 ° C./min was taken as the melting point.

Example 1 Containing 5% by weight of octene-1 and having a density of 0.937 g / cm ³ and a melt index value of ASTM D-1238 (E) of 40 g / 10 min, measured by DSC 90 parts by weight of linear low-density polyethylene (A) with a melting point of 128 ° C, melting point of 162 ° C, melt flow rate value of AST
A blend structure (C) consisting of 10 parts by weight of polypropylene (B ₁ ) of 30 g / 10 min measured by the method of D-1238 (L) of M is used as a sheath component, and the same polypropylene (B ₁ ) as the above is used as a core. A two-component core-sheath type composite filament used as a polypropylene (B ₂ ) component, with a single yarn fineness of 3 denier and a composite ratio (weight fraction) of the sheath component to the core component of 50/50 was spun. After being stretched by air pressure and opened, it was deposited on a moving porous strip and made into a web. A non-woven sheet having a basis weight of 50 g / m ³ was obtained by hot-pressing this web onto the entire surface of the sheet at a heat-pressing temperature of 100 ° C. and a linear pressure of 700 kg / cm using a calendering device made of a pair of metal flat rolls.

The obtained sheet has a tensile strength of 8.8 kg and air permeability of 3.9 cc /
It had a cm ² / sec, a thickness of 150μ, retained its strength, had low air permeability, and had a smooth sheet surface.

Example 2 Using polyethylene (A) and polypropylene (B) used in Example 1, except that the composite ratio (weight fraction) of the sheath component to the core component was 67/33, all other conditions were the same as in Example 1 A non-woven sheet having a basis weight of 50 g / m ² was obtained in accordance with the above.

The obtained sheet has a tensile strength of 8.4 kg and an air permeability of 1.5 cc /
The thickness was cm ² / sec and the thickness was 139μ.

Comparative Example 1 Polyethylene (A) and polypropylene (B ₁ ) and (B ₂ ) used in Example 1 were used, and according to Example 1, the fibers were deposited on the porous strip by the spunbond method. It has become a web. This web was pressed at an area ratio of 15% and a contact density of 22
Partial thermocompression bonding was performed with an embossing roller under the conditions of a heating roller temperature of 100 ° C and a linear pressure of 700 kg / cm so that the number of pieces / cm ² was set.

The obtained sheet has a basis weight of 50 g / m ² , tensile strength of 8.6 kg, and air permeability of 3
00cc / cm ² / sec, thickness 253μ, the unevenness of the surface of the non-woven fabric is large, and the air permeability is high, so it has only the performance of the non-woven fabric. Therefore, to obtain surface smoothness and low air permeability, It required film lamination or resin application.

(Effects of the Invention) According to the present invention, a composite filament made of a blend structure made of polyethylene and polypropylene and the same polypropylene as the polypropylene is melt-spun and formed into a sheet, and then only the low melting point component is made amorphous. Therefore, a composite filament non-woven sheet that combines the performance as a film and the performance as a non-woven fabric in one process without attaching a sheet-like material made of fibers and a non-fibrous sheet-like material as in the past Can be obtained. Further, the obtained sheet does not peel or separate the two components which are problematic in the case of the conventional laminated product of the nonwoven fabric and the film.

Claims (4)

[Claims] 1. A polyethylene (A) and the polypropylene (B ₁₎ a blend structure obtained by mixing and the (C) as a first component, said polypropylene (B ₁₎ the same polypropylene and (B ₂₎ a second An olefin-based composite filament nonwoven sheet comprising a two-component composite filament as a component, wherein the polyethylene (A) comprises:
An olefin-based composite filament non-woven sheet characterized in that polypropylene (B ₁ ) and polypropylene (B ₂ ) satisfy the following conditions (a), (b) and (c), respectively. (I). The polyethylene (A) is flow-indeterminate and distributed over the entire surface of the sheet, (b). The polypropylene (B ₂ ) retains the filament morphology, (C). In the fluidized amorphous polyethylene (A), at least the polypropylene (B ₁ ) and the polypropylene (B ₁ ) and the polypropylene (B ₂ ) are hot-pressed to each other. 2. The two-component composite filament has a core-sheath structure in which the first component which is the blend structure (C) completely covers the second component which is polypropylene (B ₂ ). Olefin composite filament non-woven sheet. 3. A blend structure (C) comprising 99 to 75% by weight of polyethylene (A) and _{1 to} 25% by weight of polypropylene (B ₁ ) as the first component, and the polypropylene (B ₁ )
A two-component composite filament having the same polypropylene (B ₂ ) as the second component, wherein at least the component (B ₂ ) is continuous in the axial direction of the filament and at least the component (C) in the filament. Of the two-component composite filament exposed on the surface of the filament is heat-pressed over the entire surface at a temperature lower than the melting point of the polyethylene (A) to form the composite filament (C). A method for producing an olefin-based composite filament non-woven sheet, characterized by softening or melting the polyethylene (A) in a component to make it amorphous. 4. A composite ratio (C / C) of a two-component composite filament.
The method for producing an olefin-based composite filament nonwoven sheet according to claim 3, wherein B ₂ ) (weight fraction) is 40 to 80/60 to 20.