JPH02289160A - Olefinic complex nonwoven sheet and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject sheet having excellent nonwoven fabric characteristics by performing melt spinning of conjugate fiber from a blended matter comprising polyethylene and polypropylene and polypropylene, making to sheet-like and making low-melting point component to amorphous. CONSTITUTION:(A) A blended matter mixed of (i) 99-75wt.% polyethylene and (ii) 1-25wt.% polypropylene and (B) component (ii) are subjected to conjugate spinning. Resultant two-components conjugate filament contains continuous at least the component (ii) in axial direction of the filament and the component A in the filament is bared on the surface of the filament. Then, said two- components conjugate filament is made to web and whole of the web is hot- pressed at a temperature below melting point of the component A, thus a part of the component A of the conjugate filament is softened or melted to make the component A to amorphous to afford the aimed sheet having excellent tear strength and tensile strength, etc.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention consists of two components, one component is filament-like, the other component is amorphous, and the amorphous portion has a filament shape inside. The present invention relates to existing olefin-based composite nonwoven sheets and methods for producing the same.

(Prior Art) Nonwoven fabrics made of long fibers have superior strength compared to nonwoven fabrics made of short fibers, and are therefore widely used in fields that take advantage of this feature. However, in recent years, non-woven fabrics are required not only to be strong but also to have a variety of functionality depending on their use, and in order to satisfy these demands, there are many things that cannot be achieved with non-woven fabrics alone. Much, in that case.

This is often achieved by combining nonwoven fabrics with other materials. For example, when a nonwoven fabric is required to have air permeability similar to that of a film, this can be achieved by combining these materials. In other words.

In order for a nonwoven fabric to satisfy both film-like smoothness and fabric properties such as tear properties, tensile strength, and appropriate breathability, it is necessary to
These requirements could not be achieved using conventional long-fiber nonwoven fabrics alone, and in many cases, composites have been used to meet these demands.

For example, laminates in which a thermoplastic resin film is bonded to one or both sides of a long fiber nonwoven fabric, and resin processed products in which a resin is deposited on a nonwoven fabric are known.

(Problem to be Solved by the Invention) However, in the above-mentioned composite nonwoven sheet, the long fiber nonwoven fabric and a sheet-like material such as a film are pasted together, or the long fiber nonwoven fabric is coated with a resin liquid prepared in a liquid form. Because the nonwoven fabric is manufactured using a manufacturing method, the compositing process is complicated, and the resulting sheet material also tends to peel off from the bonded parts, or if the sheet is thick, the resin cannot be deposited uniformly over the entire nonwoven fabric. There were other problems.

The object of the present invention is a two-component composite nonwoven sheet,
The manufacturing process is simple, there is no peeling between the two components, and the surface is film-like smooth.

The object of the present invention is to provide a composite nonwoven sheet having the characteristics of a nonwoven fabric, such as tear strength, tensile strength, and appropriate air permeability, and a method for producing the same.

(Means for Solving the Problems) The present inventors have conducted extensive research to solve the above problems, and as a result, they have arrived at the present invention.

In other words, the present invention provides an olefin consisting of a two-component composite filament in which one component is a blend structure (C) formed by mixing polyethylene (A) and polypropylene (B), and the other component is polypropylene (B). Component (B) is in the form of a filament, while component (C) is made into an amorphous shape by the flow of component (A), and both of the above-mentioned sheets are The gist of this paper is an olefin-based composite nonwoven sheet consisting of two-component composite filaments distributed over the entire surface of the sheet, and a method for producing the same.

As the polyethylene and polypropylene used in the present invention, 1 ordinary fibers or those used for molding can be used. Contains polypropylene, which provides excellent adhesion between the fibers that make up the nonwoven sheet. Moreover, the polyethylene itself, which forms the irregularly shaped portion of the composite nonwoven sheet, has appropriate softness. As described above, in the present invention, very good results can be obtained because the nonwoven fabric is made of a blend structure of polyethylene and polypropylene and composite fibers made of polypropylene.

The two-component composite fiber used in the present invention can be produced using a conventionally known composite spinning apparatus.

Mixing polypropylene (It) with polyethylene (A) allows for faster spinning by mixing component (13) rather than component (A) alone, resulting in thinner denier fibers. This is because a nonwoven sheet with a softer texture can be obtained. however,(
B) When the amount of the component mixed exceeds 25% by weight.

On the other hand, if the spinnability becomes poor, and if the amount of the (B) component mixed is 1% by weight without grooves, the spinability is the same as that of the polyethylene (A) component alone, so the amount of the (n) component mixed is 1% by weight. ~25% by weight is preferred.

Composite ratio of two-component composite filament ((B) component and (C)
) The weight fraction of the component) should be determined depending on the purpose of use of the composite acyclic sheet after being heat-pressed and should not be particularly limited. In other words, when the amount of component (C) is large, the obtained nonwoven sheet has many irregularly shaped parts.
This results in a sheet with little or no air permeability. Conversely, if the amount of component (C) is small, the sheet will have fewer irregularly shaped portions and will have high air permeability.

Next, the fineness of the two-component composite fiber should also be determined depending on the intended use of the nonwoven sheet that will become the final product. In other words, since the nonwoven sheet is composed of two-component composite filaments, it maintains its fiber shape while retaining the remaining CB.
The performance of the nonwoven sheet is determined by the fineness of component () and the weight ratio of component (C) mentioned above.

Mechanical properties such as strength will be determined.

As described above, in the two-component composite fiber of the present invention, there are no restrictions on the weight ratio of component (C) and component CB) and the fineness, but if productivity and texture are taken into consideration, the fineness is 1 to 20 denier.

The weight ratio of component (C) to component (B) is 0.2 to 1
A range of 0 is desirable.

To obtain the composite nonwoven sheet that is the object of the present invention.

Since the two-component composite fibers are welded under heat over the entire surface after forming the web, it is necessary that the deformed or melted polyethylene (A) be distributed almost uniformly over the entire surface of the web.

Therefore, it is necessary that the (C) component as well as the (B) component is continuous in the length direction of the filament. Specifically, the (C) component must be continuous with the (B) component. Either the so-called core-sheath structure is wrapped everywhere, or the (C) component does not wrap around the (B) component, but (
Both component C) and component (B) are continuous. A so-called side-by-side structure is desirable.

Regarding the above-mentioned core-sheath structure, the cross-sectional shape is generally such that the inner layer portion and the outer layer portion are almost concentric circles, but it is also a so-called multi-core structure in which one fiber has two or more core components. There may be. In addition, the cross-sectional shape does not necessarily have to be circular, but in particular, the outer layer (
^) Since the ingredients are made into an amorphous shape by thermo-pressure welding, considering productivity etc.

At least the outer layer does not need to have an irregular cross section.

In the case of the composite nonwoven sheet of the present invention, since the polyethylene (A) in the component (C) is deformed or melted by thermal welding, not all of the filaments constituting the web have a two-component composite structure. It is not necessary for the fiber to have That is, fibers consisting of component (A) alone may be included, and it is sufficient that continuous filaments are 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 nonwoven sheet.9 Considering the composite ratio of the present invention, the weight ratio of the two-component composite filament and other fibers is important. The ratio is
The weight ratio of the two-component composite filament is at least 80%
It is preferable that it is above. If it is less than 80%, the resulting nonwoven sheet will not have a uniform composite structure over the entire surface (this will result in areas where only either the blend structure (C) or the polypropylene (B) component is present). becomes more.

The nonwoven sheet targeted by the present invention cannot be obtained.

As described above, the effects of the present invention can be best exhibited when all of the filaments constituting the web have a two-component core-sheath type composite structure, but this is not necessarily the case. ) If the component is distributed over the entire surface of the sheet in the form of filaments, similar effects can be expected.

Next, the fibers spun according to the present invention are deposited.

Conventionally known techniques can also be used to create a web version. In other words, a common method is to draw the spun two-component composite fiber using air pressure and transport the fiber while depositing it on a moving filament. However, the deposition and web formation in the present invention are not limited to this method, and the fibers are kept in a state where they can be considered as continuous filaments, and moreover, the fibers are almost entirely distributed over the entire surface without significant deviation in direction. It goes without saying that methods for producing nonwoven fabrics that can be deposited uniformly can also be used.

In addition, for the convenience of continuously producing nonwoven sheets9, for example, for the convenience of web transportation, the deposited web may be partially fixed by heat pressure welding before being fully heat pressure welded, or the web may be fixed by needle bunching. There are no particular restrictions on the method of entangling the web or using a needle bunch to entangle the web after partial heat-pressure welding.

The purpose of the full-surface thermocompression welding in the present invention is to soften or partially melt the low melting point component of the fibers with a two-component composite structure constituting the web, and to make the fibers into an amorphous shape. The pressure welding method will be limited. First, it is essential that the thermocompression welding method is a method that can apply pressure almost uniformly and over the entire surface of the web. Specifically, it is a calender device consisting of a pair of flat rolls or something similar thereto. There are no particular restrictions on the material of the roll, but since heating and pressure are usually performed at the same time in this calendar device, metal/metal combinations or metal/heat-resistant elastic material combinations are common. It should be noted that there is no limit to repeating the thermocompression welding process several times for the purpose of uniform thermocompression welding over the entire surface, and it is necessary to change the temperature of the thermocompression welding component (A).

The thermocompression welding temperature must be at least the glass transition point of component (A), and the upper limit must be less than the melting point of component (A). When hot pressure welding is carried out, the molten component (A) adheres to the heat pressure welding device, resulting in increased dirt on the rollers.

Production problems arise. Note that the melting point here refers to the temperature that indicates the maximum amount of heat absorbed when the temperature and amount of heat are measured while increasing the temperature using a differential scanning calorimeter. In addition, the upper limit of the thermocompression welding temperature is mainly limited by the production problem of polyethylene (A) being fused to the thermocompression welding equipment, so it is closely related to the processing speed, and it is not just the temperature. On the other hand, at lower processing speeds, there is a higher possibility of welding to the thermocompression equipment even at lower temperatures.

Higher processing speeds reduce the possibility of fusion even at higher temperatures. However, in any case, if thermo-pressure welding is carried out at a temperature above the melting point of component (A), there is an extremely high possibility of fusion, so in the present invention, heat-pressure welding is performed at a temperature above the melting point of polyethylene (A) isn't it.

Therefore, the thermocompression welding temperature should be determined depending on the performance of the target product, and although it cannot be determined generally, it is usually 10 to 3 times lower than the melting point of polyethylene (A).
A temperature as low as 0°C is preferred.

(Function) The present invention makes use of the difference in melting point of thermoplastic resins constituting a two-component composite fiber, and makes only one component into an amorphous shape by fluidizing the low melting point component, but almost no high melting point component is formed. Since it is not thermally deformed, the low melting point component exhibits the performance of the composite nonwoven sheet as a film, and most of the high melting point component exhibits the performance of the nonwoven fabric. Furthermore, since both of the two components contain polypropylene (B), the amorphous portion and the filament-shaped portion can be integrated.

Therefore, the adhesion at the interface between the two composite components is improved.

In addition, in conventional two-component nonwoven sheets, the low melting point component was only required to function as an adhesive component that maintains the shape of the nonwoven fabric, whereas in the composite nonwoven sheet of the present invention, the two-component Since all of the composite fibers contain polypropylene (El), the low-melting point component can provide adhesive functions and sheet film-like functions, that is, smoothness and low air permeability functions, making it possible to use thermo-pressure welding. When this is done, the feature is that a sense of unity can be obtained between both the amorphous portion and the filament-shaped portion. Also.

The manufacturing method is also not the conventional method of laminating nonwoven fabric and film or impregnating nonwoven fabric with resin, but the composite nonwoven sheet is obtained by heat-pressing the entire surface of the nonwoven sheet. It is possible to eliminate the drawbacks of composite sheets such as peeling of the resin and spots of resin adhesion.

(Example) The present invention will be specifically explained with reference to Examples. In addition.

The measurement methods used in this example are summarized below.

(1) For a sample with a tensile strength width of 3ca+ and a length of 30cm, a constant speed extension type tensile tester was used to test the tensile strength at 100% for 1 minute at a word length of 20C11.
The test was conducted at an elongation rate of , and the stress at cutting was measured.

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

(3) Melting point of polymer The melting point of polyethylene and polypropylene was measured using a PerkinElmer DSCZ differential scanning calorimeter at a heating rate of 20°C/min, and the melting point was defined as the temperature showing the maximum value of the melting endothermic peak. .

Example 1 Contains 5% by weight of octene-1 and has a density of 0.937g/
ca! , melt index value is ASTM o-1
40g/10 minutes, DS as measured by the method of 238(E)
1 part of linear low density polyethylene (A) 901°C with a melting point of 128°C as measured by C, a melting point of 162°C as measured by DSC and a melt flow rate value of AS
TM's D-1238, which is a two-component core-sheath type composite fiber containing the above-mentioned polypropylene (B) as a core component, with a single fiber fineness of 3 denier and a composite ratio (weight fraction) of the sheath component to the core component of 50150. The composite filaments were spun, pneumatically drawn and opened, and then deposited on a moving porous strip to form a web. This web was heat-pressed onto the entire surface of the sheet using a calender device consisting of a pair of metal flat rolls at a heat-pressing temperature of 100° C. and a linear pressure cuff of 00 kg/cta to obtain a nonwoven sheet with a basis weight of 50 g/rrr.

The performance of the obtained sheet is that the tensile strength is 8.8 kg, the air permeability is 3.9 cc/aJ/sec, and the thickness is 150μ, and it maintains 9 tensile strength, 5 low air permeability, and a smooth sheet surface. It was something.

Example 2 All other conditions were the same as in Example 1, except that polyethylene (A) and polypropylene (B) used in Example 1 were used, and the composite ratio (weight fraction) of the sheath component to the core component was 67/33. Create a non-woven sheet according to
A nonwoven sheet was obtained.

The properties of the obtained sheet were that the tensile strength was 8.4 kg, the air permeability was 1.5 cc/aj/sec, and the thickness was 139 μm.

Comparative Example 1 Using the polyethylene (A) and polypropylene (B) used in Example 1, the above fibers were deposited on a porous strip by the spunbond method to form a web according to Example 1. This web has a pressure contact area ratio of 15% and a pressure contact point density of 22 pieces/c.
si, thermal welding was performed using an embossing roller under the conditions of a heating roller temperature of 100°C and a vA pressure cuff of 00 kg/cm.

The obtained sheet had a basis weight of 50 g/rrf and a tensile strength of 8.
6kg, air permeability 300cc/al/sec, thickness 2
53μ, the surface of the nonwoven fabric has large irregularities, and the air permeability is high.As it is, it only has the performance of a nonwoven fabric, so in order to obtain smoothness and low air permeability on the surface, it is necessary to laminate one film or add a resin. It was what I needed.

(Effects of the Invention) According to the present invention, a blend structure made of polyethylene and polypropylene and a composite fiber made of polypropylene are melt-spun and formed into a sheet, and then only the low melting point component is made into an amorphous shape, unlike the conventional method. A composite nonwoven sheet having both the performance as a film and the performance as a nonwoven fabric can be obtained in the second step without bonding a sheet-like material made of fibers and a sheet-like material that is not fibrous. Moreover, the obtained sheet is one in which the two components do not peel or separate, which is a problem in the case of laminated products.

Patent applicant: Yu-Tei Riki Co., Ltd.

Claims (4)

[Claims] (1) A blend structure made by mixing polyethylene (A) and polypropylene (B). One component is a blend structure (C), and the other component is polypropylene (B). A woven sheet,
In the nonwoven sheet, the component (B) is in the form of a filament, while the component (C) is amorphous due to the flow of the component (A), and both are distributed over the entire surface of the sheet.
Olefin-based composite nonwoven sheet consisting of component-based composite filaments. (2) The two-component composite filament has a blend structure (
The olefin-based composite nonwoven sheet according to claim 1, wherein C) has a core-sheath structure that completely covers component (B). (3) A two-component composite filament consisting of a blend structure (C) made by mixing 99 to 75% by weight of polyethylene (A) and 1 to 25% by weight of polypropylene (B) and polypropylene (B). A web consisting of a two-component composite filament in which the component B) is continuous in the axial direction of the filament and at least component (C) in the filament is exposed on the filament surface is completely coated with polyethylene (A). Heat pressure welded at a temperature below the melting point,
(C) of the above composite filament constituting the web;
A method for producing an olefin-based composite nonwoven sheet, which comprises softening or melting a part of the components and making component (C) amorphous. (4) Composite ratio (weight fraction) of two-component composite filament
The method for producing an olefin-based nonwoven sheet according to claim 3, wherein (C)/(B)=20-80/80-20.