JPH04263660A - Production of low-basis weight nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain a low-basis weight nonwoven fabric having excellent formation and required strength by laminating a staple fiber web to at least the top surface of a netlike sheet and then carrying out treatment with a high-speed water stream. CONSTITUTION:A film is fibrillated and extended into the form of a net to provide a netlike sheet having 5-20g/m<2> basis weight. A staple fiber web having 5-40g/m<2> is then laminated to at least the top surface of the resultant netlike sheet. A high-speed water stream is subsequently jetted on the aforementioned laminate to entangle fibers in the above-mentioned staple fiber web alternately and with the aforementioned netlike sheet. Thereby, the objective low-basis weight nonwoven fabric is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a low basis weight nonwoven fabric in which fibers are entangled by high-speed water treatment.

(Prior Art) Conventionally, a method for manufacturing a nonwoven fabric in which fibers are entangled by high-speed water treatment is known.

The present inventors have published JP-A-57-39268, JP-A-59
In No. 125954, the above-mentioned effective method for producing a low basis weight nonwoven fabric having a uniform texture with substantially no density unevenness and a required strength has already been proposed.

(Problems to be Solved by the Invention) However, when producing a low basis weight nonwoven fabric by using a low basis weight fibrous web as a material to be treated and interlacing the fibers with high speed water treatment, it has been found that there are points that need to be further improved. In other words, as the basis weight of the short fiber web to be processed is reduced, the texture of the fiber web is disturbed due to tension in the direction of movement during the movement process for processing, and as a result, density unevenness occurs, resulting in a nonwoven fabric having the required strength. was not obtained, and it was found that this should be improved.

An object of the present invention is to provide a method for producing a nonwoven fabric that does not suffer from the above-mentioned drawbacks even when a low basis weight fiber web is used as the material to be treated.

(Method for Solving the Problems) The present invention for solving the above problems involves laminating a short fiber web on at least the upper surface of a sheet, guiding this laminate to a support, and subjecting it to high-speed water jet treatment on the support. The following method is used to produce a nonwoven fabric by interlacing fibers.

That is, the short fiber web has a basis weight of 5 to 40 g/
m2, and the sheet has a fabric weight of 5 to 20 when the film is fibrillated and expanded into a net shape.
g/m2 of the net-like sheet and the treatment intertwines the fibers of the short fiber web with each other and with the net-like sheet.

(Example) The embodiments of the method of the present invention will be described as follows.

As illustrated in FIG. 1, the material to be treated in the method of the present invention is one in which a short fiber web 2 having a basis weight of 5 to 40 g/m2 is laminated on the top surface of a net-like sheet 1 having a basis weight of 5 to 20 g/m2.

Net-like sheet 1 and short fiber web 2 have a basis weight of 5 g/m2
If it is less than 20 g/m2, density unevenness will occur in the treatment process described later, making it impossible to obtain a nonwoven fabric having a substantially uniform texture. If it exceeds m2, the short fiber web 2
The fibers are not sufficiently intertwined with the net-like sheet 1, and the fibers tend to fall off from the net-like sheet 1.

As the net-like sheet 1, a film obtained by fibrillating a film and expanding it into a net shape is used. In FIG. 3, a net-like sheet 1 is illustrated. The net-like sheet 1 is one in which continuous filaments 3 are partially connected.

As the short fiber web 2, all natural fibers and synthetic fibers conventionally commonly used in nonwoven fabrics can be used alone or in mixtures. The length of these fibers is not particularly limited as long as guarding is possible, but generally 100
Although the diameter is not particularly limited and the fineness is not particularly limited, it is generally 12 denier or less.

Further, as the material to be treated, as shown in FIG. 2, a material obtained by laminating short fiber webs 2 and 2' on the upper and lower surfaces of a net-like sheet 1 can also be used.

However, in this case, as the basis weight of the short fiber web 2' on the lower surface increases, the fibers of the short fiber web 2 become more concentrated in the net-like sheet.
The fibers are not sufficiently intertwined, and the fibers tend to fall off from the net-like sheet 1. Incidentally, when the material to be treated is a material in which the short fiber web 2' is laminated only on the lower surface of the net-like sheet 1, the fibers of the short fiber web 2' are hardly entangled with the net-like sheet 1.

Although not shown, the material to be treated is introduced onto the upper surface of a support, preferably a non-porous support having a substantially smooth surface, and is preferably sprayed at a pressure of 3 from an orifice disposed above the support.
The fibers of the short fiber web 2 are entangled with each other and with the net-like sheet 1 by treatment with a fine water stream of less than 5 kg/cm 2 . The orifice preferably has a hole diameter of 0.
．． 05 to 0.2 mm, and are arranged in multiple rows on the lower surface of the pipe at intervals of 2 mm or less. Although not shown in the drawings, in carrying out the present invention, there are
It is preferable to go through the steps in the method for manufacturing a nonwoven fabric disclosed in No. 4. In these manufacturing methods, the fibers of the material to be treated are entangled in a preliminary treatment step, and then the fibers are further entangled in stages in a full-scale treatment step. I will briefly explain about this. In other words, the support in the pretreatment process is a wide non-porous belt placed between rotating rolls, or a perforated belt (mesh screen) placed between rotating rolls at a predetermined interval, with a narrow support surface on the lower surface. It is possible to use a structure in which non-porous supports are arranged in contact with each other, and a structure in which a plurality of non-porous rolls are arranged at a predetermined interval can be used as the support in the full-scale treatment process. When using only the short fiber web 2 as the material to be treated and fiber-entangling it by high-speed water jet treatment such as the above-mentioned injection pressure in a treatment step in which such a support is arranged, in order to obtain the required low basis weight nonwoven fabric, As the basis weight of the short fiber web 2 is reduced, the texture of the web becomes irregular due to tension in the moving direction during the process of moving the short fiber web 2 for processing. Further, even if a random web is used as the short fiber web 2, the tension causes the fibers of the web to be arranged in the direction of movement, resulting in a difference in strength in the longitudinal and lateral directions, reducing the strength of the entire nonwoven fabric.

(Effects of the Invention) According to the method of the present invention, a short fiber web is laminated on at least the upper surface of a net-like sheet whose structure does not collapse during fiber entanglement by high-speed water treatment, unlike a short fiber web in which fibers are simply accumulated. Since the treated material is used as the treated material, even if the treated material, especially the short fiber web, has a low basis weight,
A nonwoven fabric with good texture and required strength can be obtained.

[Brief explanation of the drawing]

1 and 2 are schematic cross-sectional views of a material to be treated in the method of the present invention. FIG. 3 is a schematic plan view showing an example of a net-like sheet forming a part of the processing material.

Claims (1)

[Claims] A method for producing a nonwoven fabric in which a short fiber web is laminated on at least the upper surface of a sheet, the laminate is guided to a support, and the fibers are entangled on the support by high-speed water treatment, comprising: The film has a basis weight of 5 to 40 g/m2, and the film is fibrillated as the sheet,
A low basis weight nonwoven fabric, characterized in that a net-like sheet having a basis weight of 5 to 20 g/m2 is used which is expanded into a net-like shape, and the fibers of the short fiber web are intertwined with each other and with the net-like sheet in the above-mentioned treatment. manufacturing method.