LOW LEACHABLE FIBERS AND FIBER STRUCTURE

Abstract

A fiber including olefin-based resin, wherein temperatures of the olefin-based resin losing five percent by weight and the fiber losing five percent by weight have a difference of 20 degrees Celsius or below according to thermogravimetric measurements. The fiber can reduce the leaching of impurities with low molecular weight by controlling the deterioration of olefin-based resin when heated during its spinning process.

Claims

1. A fiber comprising olefin-based resin, wherein temperatures of the olefin-based resin losing five percent by weight and the fiber losing five percent by weight have a difference of 20 degrees Celsius or lower according to thermogravimetric measurements.

2. The fiber of claim 1, wherein the olefin-based resin is cyclic olefin-based resin.

3. The fiber of claim 1, wherein all or part of a surface of the fiber is the olefin-based resin.

4. The fiber of claim 3, wherein the fiber is a core-in-sheath-type composite fiber, a sea-island-type composite fiber or a parallel-type composite fiber.

5. A fiber structure made from the fiber of claim 1.

6. The fiber structure of claim 5, wherein the fiber structure is a filter or a medical fiber structure.

Description

EXAMPLES

[0061] The present invention is described below based on examples. Note that the present invention shall not be limited to these examples. These examples may be modified and changed based on the intent of the present invention. Such changes and modifications shall not be excluded from the scope of the invention.

Example 1

Preparation of the Fiber

[0062] The fiber for the present example (single filament fineness 3.3 dtex) was obtained by melt extruding a cyclic olefin-based copolymer (using the TOPAS8007S-04 made by Polyplastics Co., Ltd.) with a MFR of 32 and that has a glass transition temperature of 78 degrees Celsius upon setting the temperature of the extruder and the pipe at 270 degrees Celsius in an environment where the extruder and the pipe are purged of nitrogen, discharged through a nozzle with a pore diameter of 0.12 mm, and wound at a speed of 1500 m/minute.

[0063] (Measuring the Temperature of Losing Five Percent by Weight)

[0064] The weight change of the cyclic olefin-based copolymer (raw material resin) and the prepared fiber were measured under a nitrogen atmosphere using a thermogravimetric apparatus (using a TG-DTA Heat Analysis Apparatus Thermoplus 2 made by Rigaku Co., Ltd.).

[0065] More specifically, the measurements were taken under the conditions of the test weight being approximately 10 mg and the temperature being raised at a speed of 10 degrees Celsius per minute, and the temperature of losing five percent by weight was set as the temperature at which five percent of the mass of the test weight was lost since the measurements began. The difference between the temperatures of the cyclic olefin-based resin losing five percent by weight and the fiber losing five percent by weight was calculated with thermogravimetric analysis. Table 1 shows the results.

Evaluation of Leachability

[0066] An extraction solution was prepared by placing 1 g of the prepared fiber in 100 ml of pure water for 24 hours at 25 degrees Celsius. The total organic carbon (TOC) value (mg/L) of the extraction solution was measured by a TOC measurement apparatus (using TOC150 made by Toray Engineering Co., Ltd.) and was set as the amount of organic material eluted from the fiber. Table 1 shows the results.

Example 2

[0067] The fiber for the present example (single filament fineness 1.7 dtex) was made by melt extruding a cyclic olefin-based copolymer (using the TOPAS6013S-04 made by Polyplastics Co., Ltd.) with a MFR of 14 and a glass transition temperature of 138 degrees was used as a raw material resin upon setting the temperature of the extruder and the pipe at 280 degrees Celsius in an environment where the extruder and the pipe are purged of nitrogen, discharged through a nozzle with a pore diameter of 0.12 mm, and wound at a speed of 1500 m/minute.

[0068] Similar to Example 1 above, the temperature of losing five percent by weight was measured and the leachability was evaluated. Table 1 shows the results.

Example 3

[0069] A fiber (single filament fineness 1.7 dtex) was made in the same manner as Example 2 except with the alteration of setting the temperature of the extruder and the pipe at 300 degrees Celsius. Similar to Example 1 above, the temperature of losing five percent by weight was measured and the leachability was evaluated. Table 1 shows the results.

Example 4

[0070] A cyclic olefin-based copolymer (TOPAS6013S-04 made by Polyplastics Co., Ltd.) with a MFR of 14 and a glass transition temperature of 138 degrees was set as the sheath component, and a thermoplastic copolymer made from polyethylene terephthalate was set as the core component. These components were bonded into a core-sheath type using a composite spinning apparatus with a round cross-sectional base that was purged of nitrogen at a spinning temperature of 300 degrees Celsius and a composite rate (cyclic olefin copolymer/polyethylene terephthalate) of 50/50 (weight ratio), and collected. The fiber (single filament fineness 2.0 dtex) having a core-sheath type structure of the present example was obtained after the yarn was spun out, cooled, solidified, and wound in a bobbin through a take-up roller.

[0071] Similar to Example 1 above, the temperature of losing five percent by weight was measured and the leachability was evaluated. Table 1 shows the results.

[0072] For the present example, the temperature of losing five percent by weight was set as the temperature when the mass ratio (50 mass percent) of the sheath component compared to the entire core-sheath conjugated fiber was reduced by five percent (the 47.5 percent mass loss, which is a five percent loss of the 50 mass percent). Table 1 shows the results.

Example 5

[0073] A fiber (single fiber fineness 3.3 dtex) was prepared in the same manner as Example 1 except with the alterations that a polypropylene (Y2005GP made from Prime Polymer Co., Ltd.) having a melting point of 161 degrees Celsius and a MFR of 20 was used as a raw material resin that was melt extruded from an extruder and a pipe, both purged of nitrogen, at a temperature of 300 degrees Celsius. Similar to Example 1 above, the temperature of losing five percent by weight was measured and the leachabiliity was evaluated. Table 1 shows the results.

Comparative Example 1

[0074] A fiber (single fiber fineness 3.3 dtex) was made in the same manner as Example 1 except with the alteration of setting the temperature of the extruder and the pipe at 450 degrees Celsius for melt extrusion. Similar to Example 1 above, the temperature of losing five percent by weight was measured and the leachability was evaluated. Table 1 shows the results.

Comparative Example 2

[0075] A fiber (single fiber fineness 1.7 dtex) was prepared in the same manner as Example 2 except with the alteration of setting the temperature of the extruder and the pipe at 310 degrees Celsius and that both the extruder and the pipe were not purged of nitrogen. Similar to Example 1 above, the temperature of losing five percent by weight was measured and the leachability was evaluated. Table 1 shows the results.

TABLE-US-00001 TABLE 1 Comparative Comparative Raw Material Resin Example 1 Example 2 Example 3 Example 4 Example 5 Example 1 Example 2 Cross-Section of the Fiber Circle Circle Circle Core-Sheath Circle Circle Circle type type type type type type type Resin Resin B (50 mass percent PET Core Sheath Resin Resin (50 mass part part A*.sup.1 B*.sup.2 percent) PP Resin A Resin B Resin B PET Resin B PP Resin A Resin B Spinning 270 280 300 300 300 450 310 Temperature ( C.) Nitrogen Purge Yes Yes Yes Yes Yes Yes No Temperature of 443 449 453 385 435 436 432 452 366 420 414 Losing Five Percent by Weight ( C.) Difference in 8.0 13.0 17.0 1.0 19.0 23.0 35.0 Temperature of Losing Five Percent by Weight ( C.) TOC (mg/L) 0.54 0.52 0.65 0.80 0.93 1.20 1.70 *.sup.1Cyclic Olefin-Based Resin Copolymer (TOPAS8007S-04) *.sup.2Cyclic Olefin-Based Resin Copolymer (TOPAS6013S-04)

[0076] In Table 1, the PET is polyethylene terephthalate and the PP is polypropylene.

[0077] Regarding the fiber from Example 1 to Example 5 that each have a difference of 20 degrees Celsius or below between the temperatures of the olefin-based resin and the fiber respectively losing 5 percent by weight according to thermogravimetric measurements, it can be said that the TOC value is remarkably low and the leaching of impurities (organic materials) has been reduced compared to Comparative Examples 1 as shown in Table 1. It seems that the deterioration of the cyclic olefin-based resin from heating during the spinning process was reduced in Example 1 through Example 5 because they had a difference in temperature of losing five percent by weight of twenty degrees Celsius or below.

[0078] Regarding how the spinning temperature of Comparative Example 1 (450 degrees Celsius) is higher compared to the spinning temperature of Example 1 (270 degrees Celsius), the cyclic olefin-based resin in Comparative Example 1 thermally decomposed during the spinning process and, as a result, it seems that the TOC value rose.

[0079] Since the nitrogen purge was not performed in Comparative Example 2, the cyclic olefin-based resin thermally decomposed due to the nitrogen during the spinning process and, as a result, it seems that the TOC value rose.

INDUSTRIAL APPLICABILITY

[0080] As explained above, the present invention is a fiber including cyclic olefin-based resin that is suitable for use by filters or medical fiber structures.