JPH02472B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a nonwoven fabric, and more specifically, the present invention relates to a method for producing a nonwoven fabric that satisfies required properties such as texture, compression properties, and absorption performance, suppresses fluffing of the edges, and has good quality. The present invention relates to a method for producing nonwoven fabrics that are particularly suitable for sanitary products. [Prior art and its problems] In recent years, with the development and sale of composite fibers made of two types of thermoplastic polymers with different melting points, nonwoven fabrics made of heat-fusible fibers have been continuously produced as dry-processed nonwoven fabrics. , and is used for filters, clothing, sanitary products, etc. When attempting to obtain a highly bulky nonwoven fabric using such a method, crimped fibers are usually used, which naturally increases the thickness of the nonwoven fabric. The constituent fibers of the nonwoven fabric have a three-dimensional structure, and depending on the required properties such as texture, strength, and compression properties, heat-fusible fibers may have a three-dimensional structure.
Fibers having a melting point equal to or higher than the high melting point side of the heat-fusible fibers (these are called non-heat-fusible fibers) may be partially mixed. In such cases, if a nonwoven fabric is produced by fusing heat-fusible fibers by passing the web continuously through a heat treatment machine, the three-dimensional arrangement of the fibers and/or the mixture of non-heat-fusible fibers will result in heat-fusible properties. Fibers do not necessarily fuse together sufficiently. In such a state, the nonwoven fabric is cut to a certain width in the winding direction, or when the nonwoven fabric is used as a surface material for sanitary products such as diapers and sanitary napkins. Some of the short fibers that make up the nonwoven fabric are pulled out by the force of the cutter at the edges (selvedges), and tend to become fluffy, impairing the quality of the product. The reason for this is thought to be that the binding force of the heat-fusible fibers and/or non-heat-fusible fibers within the nonwoven fabric becomes low. One way to prevent this fluffing is to press the entire surface or most of the nonwoven fabric with a roll or the like immediately after leaving the heat treatment machine, but this method significantly reduces the bulkiness and improves the texture. It becomes hard and is not very suitable as a surface material for sanitary products. [Means for Solving the Problems] As a result of intensive research to solve the above problems, the present inventors found that immediately after heat-sealing the heat-fusible fibers together, the heat-fusible fibers adhere to each other. By pressing the vicinity of the cut portion where the nonwoven fabric is cut to a certain width in the winding direction and then cutting the nonwoven fabric, the fiber adhesion of the nonwoven fabric edge after cutting is increased, and the edge is The present inventors have discovered that it is possible to improve the restraint of the constituent fibers of the fibers, and have completed the present invention. That is, the present invention provides a web containing heat-fusible fibers made of two different types of thermoplastic polymers having melting points different by 10°C or more at a temperature higher than the low melting point and lower than the high melting point. Heat treated with
Immediately after the heat-fusible fibers were heat-fused together, the heat-fusible fibers were pressed in the vicinity of the cut portion where the nonwoven fabric was cut to a constant width in the winding direction while the heat-fusible fibers had adhesive ability. The present invention provides a method for producing a nonwoven fabric, which is characterized in that the nonwoven fabric is then cut. By the method of the present invention, the adhesion of the heat-fusible fibers in the edge portion of the cut nonwoven fabric is increased compared to the inner part of the edge, and the heat-fusible fibers constituting the nonwoven fabric and/or
The restraint properties of non-thermal fusible fibers can be improved. The heat-fusible fiber used in the present invention is composed of two types of thermoplastic polymers whose melting points differ by 10°C or more, and the melting point of the low-melting thermoplastic polymer is 110°C to 140°C. The melting point of the high melting point thermoplastic polymer is preferably 160° C. or higher. The mixing ratio of these two types of thermoplastic polymers is preferably in the range of 40/60 to 60/40 (weight ratio). If the amount of the low melting point thermoplastic polymer is larger than the above range, preferred fiber properties cannot be obtained, and if the amount of the high melting point thermoplastic polymer is larger than the above range, the adhesive force will not be sufficient. Specific examples of the heat-fusible fibers used in the present invention include polyolefin fibers, polyester fibers, polyamide fibers, polyacrylonitrile fibers, or those having a melting point difference of 10°C or more, preferably 20°C or more. Examples include combinations of any two types of A difference in melting point of 10°C or more means that if it is smaller than 10°C, it is due to variations in the temperature of heat medium such as air or steam when heat-treating with a heat treatment machine and fusing the heat-fusible fibers.
This is because the polymer on the higher melting point side of the nonwoven fabric may also partially melt, damaging the fiber morphology. The web used in the present invention may also contain non-thermal fusible fibers having a melting point equal to or higher than the high melting point of the heat fusible fibers. In the present invention, the width of the pressed portion of the cut end (selvage) in the winding direction is preferably 3 mm or more and 15% or less of the nonwoven fabric width. By making this width, most of the nonwoven fabric maintains high bulkiness in the width direction, satisfies required properties such as texture, compression characteristics, and absorption performance, and also prevents fuzzing at the edges. A nonwoven fabric for sanitary products with good quality can be obtained. In other words, if the width of the pressed portion of the ear in the winding direction is narrower than 3 mm, it is insufficient to suppress fuzzing, and the width of the pressed portion of the ear in the winding direction is narrower than 3 mm. If it exceeds 15%, it is not preferable because it impairs the requirements of having high bulkiness, good hand feel, compression properties, and absorption performance. [Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Example 1 (1) Fiber composition of nonwoven fabric Polyethylene (melting point 130
°C), polypropylene (melting point
163℃) at a ratio of 50/50 (weight ratio).
Denier x 5mm cut length (manufactured by Chitsuso Co., Ltd.)
(trade name “ES” fiber) was used as the heat-fusible fiber. (2) Weighing of nonwoven fabric: 25 g/m ² (3) Manufacturing conditions Immediately after heat treating the fiber web with the above configuration in a heat treatment machine at 140°C, the pressed width of the edge after cutting is 2 mm, 3 mm, and 5 mm, respectively. After pressing the area near where the nonwoven fabric will be cut to the same width, the width of the nonwoven fabric will be
A nonwoven fabric was obtained by cutting it to a length of 180 cm. In addition, for comparison, we also produced products without pressing and products in which the entire surface of the nonwoven fabric was pressed. (4) Evaluation of physical properties and results The texture, bulkiness, absorbency, and fluffiness of the edges of the obtained nonwoven fabric were evaluated according to the following criteria. The results are shown in Table 1. <Evaluation criteria> 〇: Good △: Fairly poor ×: Poor

[Table] Example 2 (1) Fiber composition of nonwoven fabric First layer: Composite fiber containing polyethylene (melting point 130°C) as a low melting point component and polypropylene (melting point 163°C) as a high melting point component in a 50/50 (weight ratio). 3 denier x 51mm cut length (Chitsuso
100% heat-fusible fiber (manufactured by Co., Ltd., product name "ES" fiber) Second layer: 50% the same heat-fusible fiber as the first layer
and polyester (melting point 260℃) 6 denier
51mm (manufactured by Teijin Ltd.) 50% mixed fiber The above two-layer structure nonwoven fabric was obtained. (2) Weighing of nonwoven fabric 1st layer: 15 g/m ^2nd layer: 20 g/m ² (3) Manufacturing conditions A nonwoven fabric was manufactured in the same manner as in Example 1 using the fiber web having the above configuration. (4) Evaluation of physical properties and results The physical properties of the obtained nonwoven fabric were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Table] Example 3 (1) Fiber composition of nonwoven fabric First layer: Composite fiber containing polyethylene (melting point 130°C) as a low melting point component and polypropylene (melting point 160°C) as a high melting point component in a 50/50 (weight ratio). 100% heat-fusible fiber made of 2 denier x 38 mm cut length (manufactured by Daiwabo Co., Ltd., trade name "NBF") Second layer: polyethylene (melting point 130°C) as a low melting point component, high melting point component Composite fiber containing polyester (melting point 260℃) at a ratio of 50/50 (weight ratio), 3 denier x 38 mm cut length (Daiwabo Co., Ltd.)
(product name: “NBF”)
100% (2) Weighing of nonwoven fabric 1st layer: 10 g/m ^2nd layer: 10 g/m ² (3) Manufacturing conditions Example 1 except that the fiber web having the above structure was used and the heat treatment temperature was 143°C. A nonwoven fabric was produced in the same manner as above. (4) Evaluation of physical properties and results The physical properties of the obtained nonwoven fabric were evaluated in the same manner as in Example 1. The results are shown in Table 3.

【table】

Claims (1)

[Claims] 1. A web containing heat-fusible fibers made of two different thermoplastic polymers having melting points different by 10°C or more at a temperature higher than the low melting point and lower than the high melting point. Immediately after the heat-fusible fibers are heat-fused to each other by heat treatment at a high temperature, the heat-fusible fibers are cut into a constant width in the winding direction of the nonwoven fabric while having adhesive ability. 1. A method for producing a nonwoven fabric, which comprises cutting the nonwoven fabric after pressing the vicinity of the cutting part. 2 The heat-fusible fibers are made of olefin-based fibers, polyester-based materials, polyamide-based materials, polyacrylonitrile-based materials that have a melting point difference of 10°C or more, or a combination of any two types of these fibers that have a melting point difference of 10°C or more. The method for producing a nonwoven fabric according to claim 1, wherein the nonwoven fabric is a composite fiber. 3. Claim 1, characterized in that the web contains non-heat-fusible fibers having a melting point that is the same as or higher than the high melting point of the heat-fusible fibers.
Method for producing a nonwoven fabric as described in Section 1. 4. The method for manufacturing a nonwoven fabric according to claim 1, wherein the width of the pressed portion of the cut end in the winding direction is 3 mm or more and 15% or less of the width of the nonwoven fabric.