Patent Application
20080042312
It was found in the present invention that a deep-dyeable modified polylactic acid fiber having improved heat resistance and color fastness to washing can be obtained when a modifying polymer, which has good binding capability to a dispersive dye and good compatibility with polylactic acid, is added to the polylactic acid to produce a modified polylactic acid composition for the polylactic acid fiber.
The modified polylactic acid composition for forming the deep-dyeable modified polylactic acid fiber includes a polylactic acid, and 1-15% by weight of a modifying polymer based on a total weight of the modified polylactic acid composition. The modifying polymer is an aliphatic polyester other than polylactic acid, an aromatic polyester, an aliphatic-aromatic copolyester, or combinations thereof.
When the modified polylactic acid composition and a non-modified polylactic acid composition free of the modifying polymer are dyed under the same dye concentration, the modified polylactic acid composition provides a decreased L-value compared to the non-modified polylactic acid composition.
The L-value used herein is a value to measure the color fastness of a material, which is in the form of pellets, for a dyed fiber. The lower the L-value, the better will be the color fastness to washing.
If the modifying polymer contained in the modified polylactic acid composition is less than 1% by weight, the fiber cannot be deep-dyed. On the other hand, if the modifying polymer contained in the modified polylactic acid composition is more than 15% by weight, the modified polylactic acid composition cannot be processed easily to form a fiber. The modifying polymer contained in the modified polylactic acid composition ranges preferably from 1 to 10% by weight, more preferably from 1 to 5% by weight, based on a total weight of the modified polylactic acid composition.
The aliphatic polyester suitable for the present invention is represented by formula (I):
wherein R1 and R2 are the same or different, and independently of one another are linear or branched C2-C40 alkyl. Preferably, the aliphatic polyester has a melting point ranging from 30 to 140° C., and the examples thereof are polybutylene succinate (e.g., Bionolle 1020, Bionore 1001, and Bionore 1903 from Showa High Polymer Co., Ltd.), polybutylene succinate/adipate (e.g., EnPOl G400 from IRE Chemicals Ltd.), polybutylene adipate (e.g., FEPOL1000 series from Far Eastern Textile, Taiwan), polyethylene succinate/adipate, polybutylene succinate/carbonate, polycaprolactone, polyethylene adipate, and the like.
The aliphatic-aromatic copolyester suitable for the present invention is represented by formula (II):
wherein
Preferably, the aliphatic-aromatic copolyester has a melting point ranging from 50 to 200° C., and the examples thereof are polybutylene adipate/terephthalate (e.g., FEPOL2000 series from Far Eastern Textile, Taiwan, Ecoflex from BASF, or Enpol 8000 from IRE Chemicals Ltd.), polybutylene succinate/terephthalate (e.g., Biomax from DuPont), polytetramethylene adipate/terephthalate (e.g., EastarBio from Eastman Chemicals), and the like.
The aromatic polyester suitable for the present invention is represented by formula (III):
wherein
Preferably, the aromatic polyester has a melting point ranging from 110 to 200° C., and the examples thereof are polyethylene terephthalate/1,3-dihydroxy-2-methylpropane alkoxylate, polyethylene terephthalate/adipate (e.g., CS-113 from Far Eastern Textile, Taiwan), or the like.
Furthermore, the modifying polymer may further include 4-10% by weight of TiO2 based on the total weight of the modifying polymer. TiO2 is used as a matting agent, and is blended within the modified polylactic acid composition so as to produce a semi dull type of fiber.
The modified polylactic acid composition can be processed to produce a deep-dyeable polylactic acid fabric by melt spinning the modified polylactic acid composition to form a partially oriented yarn, false twisting the partially oriented yarn to form a draw-textured yarn, and forming the draw-textured yarn into the fabric.
The fiber fineness of the partially oriented yarn and the draw-textured yarn preferably ranges from 1 to 10 denier/filament, and the fiber number thereof is 36, 48, 72, 108, or 144. The fiber of the partially oriented yarn may have any suitable cross-sectional shape, such as circular, oval, trilobal, triangular, dog-boned, flat, or hollow shape.
The following examples are provided to illustrate the preferred embodiments of the invention, and should not be construed as limiting the scope of the invention.
Chemicals used in the examples:
In Examples 1-6, the PLA and a variety of the modifying polymers in different amounts, as shown in Tables 1-6, were admixed to form PLA compositions in the form of pellets. The pellets were dyed for 40 minutes at a temperature of 110° C. using a blue dispersive dye at a concentration of 2.5% owf (on the weight of fabric). The L-values of the pellets were measured. The lower the L-value, the deeper the color. Comparative Example 1 in Tables 1-3 and 5-6 is a PLA composition having no modifying polymer. In Example 4, each of Samples 1-5 contains PLA, the modifying polymer, and TiO2 as a matting agent, whereas Comparative Example 2 is a PLA composition having TiO2 but not containing the modifying polymer.
In this example, the modifying polymer included in Samples 1-5 is polybutylene succinate (PBS).
In this example, the modifying polymer included in Samples 1-5 is polybutylene succinate/adipate (EnPol)
In this example, the modifying polymer included in Samples 1-4 is polybutylene adipate/terephthalate (PBAT-FB).
In this example, the modifying polymer used in Samples 1-5 is polybutylene adipate/terephthalate (PBAT-SD), which is semi dull type. Each sample includes 6% by weight of TiO2 based on the total weight of the modifying polymer. In Comparative Example 2, pellets were formed by admixing 98% by weight of PLA and 2% by weight of masterbatch from Easterman Company. The masterbatch is composed of 85% by weight of PLA and 15% by weight of TiO2.
In this example, the modifying polymer included in Samples 1-6 is Polyethylene terephthalate/adipate (CS-113).
In this example, the modifying polymer included in Samples 1-5 is polyethylene terephthalate/1,3-dihydroxy-2-methyl propane alkoxylate (DHMPA).
From the L-values above, it is evident that the pellets containing the modifying polymer exhibit a lower L-value compared to the comparative examples containing no modifying polymer. Further, it is also evident that the greater the amount of the modifying polymer, the lower will be the L-value. The results reveal that addition of the modifying polymer to the polylactic acid enhances the deep-dyeable effect of the polylactic acid. The results also show that the deep-dyeable effect of the modified PLA composition containing the modifying polymer and TiO2 is better than that of the non-modified PLA composition containing only TiO2.
In Examples 7 and 8, modified PLA compositions were prepared by using 2% by weight and 3% by weight of PBAT-FB. The compositions were then melt spun to form partially oriented yarns of 130d/72f. The operating conditions were: 105° C. (drying temperature), 72 round spinneret holes, 220-230° C. (spinning temperature), 225° C. (Dow temperature), 0.55 m/min (cooling air speed), 0.6% (spinning oil per unit), 2780 m/min (take-up speed), and 40.4 g/min (spinning rate). The partially oriented yarns were thereafter twisted with a false twist crimping machine at a speed of 450 m/min and a draw ratio DR1/DR2=1.75 to produce draw-textured yarns of 75d/72f.
Example 9 was conducted by repeating the procedures set forth in Examples 7 and 8 except that 4% by weight of PBAT-SD was used to form the modified PLA composition, which was further processed to form the partially oriented yarns and the draw-textured yarns.
Comparative Example 3 was conducted by repeating the procedures set forth in Examples 7 and 8 except that the PLA composition used in the example did not contain the modifying polymer.
Examination of Examples 7-9 revealed that the partially oriented yarns and the draw-textured yarns obtained in all of Examples 7-9 have normal appearance and normal mechanical strength. Upon comparison with Comparative Example 3, the modified PLA compositions of Examples 7 and 8 exhibited good processability in terms of spinning and false-twisting. This reflects that there is no adverse effect on spinnability and the false twistability due to the addition of the modifying polymer.
Garters were made from the draw-textured yarns of Examples 7, 8 and Comparative Example 3, respectively. Thereafter, the garters were dyed with brown and blue dispersive dyes, respectively, in a concentration of 2.5% owf, in a bath ratio of 1:15 and a temperature of 110° C. for 40 mins. Then, the L-values and the color strengths of the garters made from Example 8 and Comparative Example 3 were measured. The results are shown in Table 7.
Additionally, garters made from the draw-textured yarns of Examples 7, 8 and Comparative Example 3 were dyed with brown and blue dispersive dyes with a dye concentration of 2.5% owf, a bath ratio of 1:15 and a temperature of 110° C. for 40 mins. Then, the garters were washed with water at a temperature of 70° C. for 15 mins, and the shapes thereof were set at 130° C. for 1.5 mins. The color fastness to washing of the garters was measured according to ISO-105C06. The results are shown in Table 7.
As shown in Table 7, the L-values of the garters made from the draw-textured yarns of Examples 7 and 8 are lower than that of the garter made from the draw-textured yarn of Comparative Example 3. That is, the garters made from the draw-textured yarns of Examples 7 and 8 exhibit a superior deep-dyeable property as compared to the garter made from the draw-textured yarn of Comparative Example 3. After being dyed with the brown dispersive dye, the color strength of the garter made from the draw-textured yarn of Example 8 was 148.7 and was determined using the color strength (100) of the garter made in Comparative Example 3 as a standard. Furthermore, after being dyed with the blue dispersive dye, the color strength of the garter made from the draw-textured yarn of Example 8 was 150.7 and was determined using the color strength (100) of the garter made in Comparative Example 3 as a standard. Additionally, as for the color fastness to washing, the grades of the garters made from the draw-textured yarns of Examples 7 and 8 are more than 3.0, which means that the color strength of the garters made from the modified polylactic acid fiber of the present invention reached the commercial standard.
Furthermore, the color strength and the color fastness to washing of the garter made from the draw-textured yarn of Example 9 were determined after the garter was dyed with blue and brown dispersive dyes following the procedures of Examples 7 and 8. The color strengths of the garters dyed with the blue and brown dispersive dyes are 163.03 and 167.24, respectively, compared to the standard value 100 of Comparative Example 3. The color fastness to washing of the garter made in Example 9 is comparable to that of the garter made in Comparative Example 3.
The biodegradation of the draw-textured yarn of Example 7 was tested according to CNS 14432 (ISO 14855, ASTM D5338). The biodegradation rate obtained from the biodegradating test is based on the percentage of carbon dioxide converted from organic carbon contained in the tested draw-textured yarn. The result is shown in Table 8. Table 8 shows that the biodegradation rate of the modified polylactic acid fiber of the present invention can reach 90% in 180 days, which meets the statutory requirement.
In view of the aforesaid, the deep-dyeable modified polylactic acid fiber of the present invention has a superior deep-dyeable property while maintaining the acceptable color fastness to washing and biodegradable properties.
While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 095123139 | Jun 2006 | TW | national |
