JP3445534B2 - High strength non-woven fabric - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field in which the surface smoothness and strong tensile strength of a nonwoven fabric are required, for example, a wire holding tape, a printing substrate, a separator, and the like. The present invention relates to a high-strength nonwoven fabric useful in fields such as filters. 2. Description of the Related Art In general, performances particularly required for wire holding tapes and the like include tensile strength, denseness and smoothness of the surface for facilitating separation from the PE sheath material, and an increase in the amount of winding. It is thin and strong because of the economic reason that it can be done. The surface smoothness of the nonwoven fabric is an important performance also from the viewpoint of clearness of printing, uniform adhesion of ink, and economy. Conventionally, in order to obtain a thin and strong nonwoven fabric having a smooth surface with a polyethylene terephthalate spunbonded nonwoven fabric, for example, as described in JP-B-57-24427, the heat-compression bonding strength is improved by using a flat cross-section yarn. The method of making it known is known. However, the strength and surface smoothness required for the wire holding tape cannot be ensured only by the method of the prior art. JP-A-55-32342 and JP-A-57-56564 disclose a method of obtaining a nonwoven fabric suitable for an electric wire holding tape by using an adhesive in addition to a flat cross-section yarn, so-called resin processing. It is shown. As described above, conventionally, in a polyethylene terephthalate spunbonded nonwoven fabric, to obtain a thin, strong nonwoven fabric with a smooth surface,
Since only the bonding by heating and pressing is insufficient in strength and smoothness, it is necessary to use resin processing together. That is, a non-binder type non-woven fabric having no surface and having a smooth surface, which is not combined with resin processing, has not been known. As a result, costs have been increased due to resin processing. Recycling of resin-treated nonwoven fabric into raw resin has also been restricted. [0004] As described above, in the prior art, resin processing was required to obtain a thin and strong nonwoven fabric having a smooth surface, and as a result, production costs were reduced. An object of the present invention is to economically provide a thin and strong nonwoven fabric only by heat-press bonding without resin processing. Means for Solving the Problems The present inventors have conducted extensive research on a non-binder type without resin processing, in other words, a thin and strong nonwoven fabric only by heating and pressing, and as a result, the present invention has been completed. . That is, the present invention provides a partially thermocompression bonded polyethylene terephthalate fiber spunbonded nonwoven fabric, wherein the nonwoven fabric is a binderless nonwoven fabric.
Ri, and the reduced viscosity of the polyethylene terephthalate fibers constituting the nonwoven fabric (ηsp / c) is 0.67 or more, fineness of 3.0 denier or less, Ri flat der the cross section of the textiles,
Further, the tensile strength per unit weight ([g / cm width] / [g /
m ^2]) is a high strength nonwoven fabric which is characterized in der Rukoto than 65. [0006] The following, a more detailed description of the present invention. The nonwoven fabric of the present invention is a nonwoven fabric in which the reduced viscosity (ηsp / c) of the polyethylene terephthalate fibers constituting the partially thermocompressed nonwoven fabric is 0.67 or more. When the reduced viscosity of the fibers constituting the nonwoven fabric after the partial thermocompression bonding is 0.67 or more, combined with the requirement that the fineness of the fibers is 3 deniers or less, the binder is not used, and only the partial thermocompression bonding is performed. A nonwoven fabric that simultaneously satisfies the strength is obtained. Polyethylene terephthalate is thermally degraded in the melt spinning step and the partial thermocompression bonding step, and the reduced viscosity of the fiber is reduced. Therefore, in order to reduce the reduced viscosity of the fibers constituting the nonwoven fabric after the partial thermocompression bonding to 0.67 or more, the raw material chips are used. It is necessary to appropriately select one having a high reduced viscosity. When the reduced viscosity of the fibers constituting the nonwoven fabric after the partial thermocompression bonding is less than 0.67, a nonwoven fabric having high strength cannot be obtained. Therefore, it is necessary to jointly use fibers by resin processing. In the nonwoven fabric of the present invention, the fineness of the polyethylene terephthalate fibers constituting the nonwoven fabric is 3.0 denier or less. When the fineness exceeds 3.0 denier, it is difficult to perform partial thermocompression bonding, and it is difficult to obtain a high-strength nonwoven fabric only by partial thermocompression bonding. Therefore, joint use of resin processing and the like are required. In the nonwoven fabric of the present invention, the polyethylene terephthalate fibers constituting the nonwoven fabric have a flat cross section. The flat shape means that the ratio of the major axis to the minor axis is 1.5 to 1.5, for example, as described in JP-A-55-32342.
It refers to those in the range of 5.0. In the nonwoven fabric of the present invention, the polyethylene terephthalate fiber has a flat cross section, the reduced viscosity of the fiber is 0.67 or more, and the fineness of the fiber is 3.0.
When the denier is equal to or less than the denier, a non-woven fabric of a non-conventional type that is thin and strong and has no binder is achieved. That is, as shown in the examples, the relationship between the reduced viscosity and the fineness of polyethylene terephthalate fiber having a flat fiber cross section is in the range of a reduced viscosity of 0.67 or more and a fineness of 3.0 denier or less, without resin processing. Tensile strength per [g
/ Cm width] / [g / m ² ]) is 65 or more. For example, the reduced viscosity is 0.67 in the flat fiber cross section.
Even with the above polyethylene terephthalate fiber nonwoven fabric, if the fiber fineness exceeds 3.0 denier, the tensile strength per unit weight ([g / cm
Width / g / m ² ) of 65 or more cannot be obtained. The nonwoven fabric of the present invention is a nonwoven fabric obtained by partially thermocompression bonding polyethylene terephthalate fibers. Usually, it is obtained by passing a fibrous web between a pair of heated and pressurized embossing rolls and a flat roll to join the fibers. It is no exaggeration to say that the final physical properties of the nonwoven fabric are determined by the partial thermocompression bonding. The area of the individual crimping points constituting the embossed pattern, the arrangement and arrangement of the crimping points, and the like can be arbitrarily selected, but the embossing ratio (crimping area ratio) is preferably from 6% to 40%. As the emboss ratio decreases, the strength of the nonwoven fabric decreases, and when it exceeds 40%, the nonwoven fabric becomes paper-like and the tear strength tends to decrease. In applications where the surface smoothness of the non-woven fabric is required, for example, in the case of printing base materials or electric wire holding tapes, a pair of flat rolls or the like may be passed through after a partial thermocompression bonding using an embossing roll as necessary. The thickness can be reduced and the surface smoothness can be further improved without impairing the tensile strength. In producing the nonwoven fabric of the present invention, various modifiers such as polyethylene terephthalate, for example, those obtained by copolymerizing a flame retardant or an antistatic agent and various additives, for example, pigments, weathering agents, antioxidants, etc. May be added. In the production of the nonwoven fabric, various additives may be added to and mixed with the polyethylene terephthalate chip in the form of a master batch at the ordinary melt spinning stage. The spinning nozzle used for spinning polyethylene terephthalate fiber can be selected from those employed in ordinary melt spinning. Similarly, the spunbond manufacturing method, for example, the spinning form is a rectangular integrated spinning method or individual spinning method, the drawing form is a roll drawing method or a high-speed airflow drawing method, and the dispersion form is a friction charging method, a corona charging method, or a webbing form. A net collecting method or a drum collecting method can be arbitrarily selected from a production method such as a single-layer web and a plurality of multilayer laminated webs. The present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The evaluation method of the polyethylene terephthalate nonwoven fabric used in Examples and Comparative Examples of the present invention is as follows. (1) Reduced viscosity [ηsp / c] A nonwoven fabric piece is sampled from an arbitrary portion of the nonwoven fabric, and reduced viscosity at a concentration of 1 g / 100 ml (temperature) 35 ° C. in a mixed solvent of tetrachloroethane / phenol and the like. (Ηsp / c) is measured. (2) Fineness (denier) Set on an optical microscope equipped with a digital microscopic eyepiece so that the cut surface of the test specimen sampled from any part of the nonwoven fabric can be observed, and it is almost perpendicular to the direction across the fiber axis. The lengths of the major axis and the minor axis of the fiber cross section are measured for 20 arbitrary fibers cut into pieces, the cross-sectional area of each fiber is obtained, and the values are averaged to calculate the cross-sectional area of the fiber. The fiber density is 1.38 g / cm ³ and the weight at a length of 9,000 m is calculated and determined. The digital microscopic eyepiece used for the measurement is a model OSM-D2 manufactured by Olympus Optical Industry Co., Ltd.
The minimum reading unit is 0.01 μm (objective lens: 100
X). Denier = fiber cross section (cm ² ) x 900,000 (c
m) × 1.38 (g / cm ³ ) (3) A sample having a width of 3 cm × a length of 20 cm and a sample having the same dimension in the direction perpendicular to the sample at the midpoint in the longitudinal direction of the non-woven fabric Sampling is performed at one point per 20 cm width. The specimen was gripped by a constant-speed extension type tensile tester with a grip length of 10
cm, and apply a load at a tensile speed of 30 cm / min until the test piece is cut. The average value of the strength of the test piece at the maximum load is determined and defined as the tensile strength (kg / 3 cm width). (4) Tensile strength per 1 mm thickness Calculated by proportional calculation from the tensile strength calculated by the method of (3) and the thickness measured by the method of (6) below. Tensile strength per 1 mm thickness = tensile strength ×
(1000 / thickness [μ]) (5) Tensile strength per unit weight The tensile strength calculated by the above method (3) is converted into the strength per 1 cm width, and the strength per 1 cm width is used as the basis weight. Divide and calculate. Tensile strength per unit weight = [tensile strength obtained in (3)] /
[3 × basis weight] (6) A sample having a width of 6.5 cm × length of 10 cm and a sample having the same dimension in a direction perpendicular to the sample at a midpoint in the longitudinal direction of the sample from the tear-resistant strong nonwoven fabric were added at one point per 20 cm width of the nonwoven fabric. Collect at the rate of Using this sample, it is measured by the JIS general textile test method (L1096) 6.15.5D method (pendulum method). The average of those values is taken as the tear strength (k
g). (7) Thickness Average value of the thickness measured under a constant load of 100 g / cm ² for each 5 cm in the width direction of the sample. The measurement was performed with a Peacock thickness gauge (R1-B type). (8) Flatness The flatness is calculated using the values of the lengths of the short axis and the long axis obtained at the time of measuring the fineness in the above (2). Flatness = length of major axis / length of minor axis (9) Surface roughness (center line average roughness: Ra) A sample having a size of about 10 cm × 10 cm is sampled from an arbitrary position of the nonwoven fabric, and the surface roughness is measured. Shape measuring device: Surfcom 1
Measure with 10A (Tokyo Seimitsu Co., Ltd.). The measurement is performed on the front and back surfaces of the nonwoven fabric, and the maximum value among them is defined as the surface roughness. Examples 1 to 7, 9, 10 and Comparative Examples 1 to 8 A 1.2 m-wide spout nozzle having a rectangular cross section having a width of 1.0 mm and a thickness of 0.1 mm and a total of 2,214 nozzles. Was used. In each of Examples and Comparative Examples, raw material chips of polyethylene terephthalate having different reduced viscosities were melt-extruded while changing the discharge amount per spinning nozzle. 0.6 denier extruded long fiber groups, respectively, 1.1 denier,
The web was formed by pulling it with a high-speed airflow so as to have 2 denier, 3 denier, and 3.5 denier as a comparative example, and collected on a wire mesh net. This web was partially thermocompression-bonded between a pair of weave pattern embossing (compression area ratio: 22.0%) rolls and flat rolls to produce each nonwoven fabric having a basis weight of 45 g / m ² . Table 1 shows the results of measuring various physical properties of each of the obtained nonwoven fabrics. The nonwoven fabric of 3.5 denier in the comparative example was examined by changing the temperature and pressure of the partial thermocompression bonding in the range of the reduced viscosity of 0.66 to 0.72, but the fiber bonding was insufficient only by the partial thermocompression bonding. The fluffing did not stop and the tensile strength did not improve. Examples 11-14, Comparative Examples 9-12 Each Example and Ratio
In the comparative example, the raw material chips of polyethylene terephthalate having different reduced viscosities, the spinning nozzle shape was 1.0 mm in width,
Melt extrusion from 1.2m width rectangular spinneret that Yusuke <br/> the 2,214 pieces total number of nozzles in a rectangular cross section of thickness 0.1 mm, and pulling at a spinning speed of 4,500 m / min at a high speed air flow, 1. An 8-denier continuous filament web was formed on a wire mesh net. This fiber web is embossed with a pair of texture patterns (crimp area ratio: 2
2.0%) Compression temperature between roll and flat roll
2. Partial thermocompression bonding was performed as shown in Fig. 2 to obtain a basis weight of 45 g.
/ M ² of each nonwoven fabric. Table 2 shows the results of measuring various physical properties of these nonwoven fabrics. The pressure during the partial thermocompression bonding was 30 kg / cm. As Comparative Examples 9 and 10, except that the Example and those changed viscosity of the raw material chips and spinning orifice nozzle shape 0.25 mm, in the same manner as in Example 1 1, and crimping shown in Table 2
Each nonwoven fabric was manufactured by partial thermocompression bonding at a temperature and evaluated.
Table 2 shows the results. The basis weight 4 under the conditions of Comparative Examples 9 and 10
To produce a 1 g / m ² nonwoven fabric, these PVA-based resin processing agent (Gosenol: NM-11) the resin processing performed in each comparative example manufactures the nonwoven 45 g / m ² 1
Table 2 shows the results as 1 and 12 . Examples 16 to 24 Example 1 was repeated except that the reduced viscosity of the polyethylene terephthalate fiber of the nonwoven fabric was 0.72.
Partial heat pressure under the same conditions as in Example 1 and at the crimping temperature shown in Table 3.
Each nonwoven fabric having a basis weight of 30 to 120 g / m ² was manufactured, and various physical properties were measured. Table 3 shows the results. The flatness of the fibers constituting the nonwoven fabric was 3.3. Examples 25 to 31, Comparative Examples 13 to 14 The nonwoven fabrics obtained in Examples 11 and 16 to 21 were treated at a temperature of 215.degree.
The surface smoothness of the nonwoven fabric was further improved through a pair of flat rolls under the condition of kg / cm. Table 4 shows the results of evaluating the performance of this nonwoven fabric. As a comparative example, Table 4 shows the results of processing the nonwoven fabrics obtained in Comparative Examples 9 and 10 under the same conditions and evaluating the performance. Examples 32 to 35, Comparative Examples 15 to 16 Under the conditions of Example 12, partial thermocompression bonding was performed using emboss rolls and flat rolls having different emboss ratios to produce a nonwoven fabric having a basis weight of 45 g / m ^2. The performance was evaluated. Table 5 shows the results. As is clear from Table 1, Table 2, Table 3, Table 4, and Table 5, the nonwoven fabric of the present invention has superior tensile strength and surface smoothness as compared with the comparative example with the same basis weight, It is possible to achieve the same tensile strength and surface smoothness as a conventional resin-processed nonwoven fabric without resin processing. [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] The nonwoven fabric of the present invention is a thin, strong nonwoven fabric having no binder and the same surface smoothness as a conventional resin processed product. This nonwoven fabric can be economically provided to, for example, an electric wire holding tape, a printing substrate, a blind, and the like.

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Claims (1)

(57) [Claim 1] In a partially thermocompression-bonded polyethylene terephthalate fiber spunbonded nonwoven fabric, the nonwoven fabric is
-Reduced viscosity (ηsp) of a polyethylene terephthalate fiber which is a binder type nonwoven fabric and constitutes the nonwoven fabric
/ C) is 0.67 or more, fineness of 3.0 denier or less, Ri cross section flat der of fiber <br/> Wei, further tensile strength per basis weight
It is ([g / cm width) / (g / m ^2]) is a high strength nonwoven fabric which is characterized in der Rukoto than 65.