TW202511558A - Biodegradable Fiber - Google Patents

Abstract

The present invention provides a biodegradable fiber which does not become brittle in a moist heat environment, and which has excellent alkali resistance. Disclosed is a biodegradable fiber which contains a blend polymer containing a polyethylene terephthalate, a polybutylene adipate terephthalate and a polylactic acid, wherein the content of the polyethylene terephthalate in the fiber is 80 mass% or more. It is preferable that the content of the polyethylene terephthalate in the fiber is at least 93 mass% or more, the content of the polybutylene adipate terephthalate in the fiber is 0.4 mass% to 2.4 mass%, the content of the polylactic acid in the fiber is 0.4 mass% to 2.4 mass%, and the ratio of the content of the polybutylene adipate terephthalate to the content of the polylactic acid is 40/60 to 60/40 in terms of the mass ratio.

Description

Biodegradable Fiber

The present invention relates to biodegradable fiber with polyethylene terephthalate as a main component.

Polyethylene terephthalate fiber is preferably used in various applications due to its excellent mechanical and chemical properties.

On the other hand, in recent years, biodegradable fibers have attracted much attention due to environmental issues. Polylactic acid fibers are a representative example.

Polylactic acid fiber has poor alkali resistance and cannot improve its texture by reducing the amount of alkali like polyethylene terephthalate, so it is not suitable for clothing. In addition, it will hydrolyze and become brittle in a humid and hot environment, so it is not suitable for automotive interior materials used in high temperature environments, and its use is limited.

As a biodegradable fiber with excellent alkali resistance, a core-sheath type composite fiber has been proposed in which polyethylene terephthalate is arranged in the sheath and polylactic acid is arranged in the core (Patent Document 1). [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2008-208482

[Problems to be solved by the invention]

However, although the fiber of Patent Document 1 is covered with polyethylene terephthalate on the surface, the core will still become brittle in a humid and hot environment, and the strength of the fiber will not be reduced. In addition, the polylactic acid in the core will dissolve when the alkali is reduced. In addition, although the polylactic acid used in the core is biodegradable, the polyethylene terephthalate used in the sheath is not biodegradable, so it is insufficient in terms of environmental load.

As mentioned above, there has been no biodegradable fiber that can be used in a wet and hot environment and exhibits alkali resistance. Therefore, the purpose is to provide a fiber that has polyethylene terephthalate as a main component and has excellent biodegradability. Furthermore, the purpose is to provide a biodegradable fiber that does not become brittle even in a wet and hot environment and has excellent alkali resistance. [Means for Solving the Problem]

As a result of repeated studies, the inventors of the present invention have found that if the fiber is composed of a blended polymer of polyethylene terephthalate as the main component and contains a specific amount of polybutylene adipate terephthalate and polylactic acid, the polyethylene terephthalate fiber, which originally shows almost no biodegradability, can be effectively biodegraded, thereby completing the present invention. That is, the purpose of the present invention can be achieved by a biodegradable fiber containing a blended polymer of polyethylene terephthalate, polybutylene adipate terephthalate and polylactic acid, and the content of polyethylene terephthalate in the fiber is 80 mass % or more. In addition, the inventors have found that fibers made of a blended polymer containing polyethylene terephthalate as the main component and a specific amount of polybutylene adipate terephthalate and polylactic acid in a specific mixing ratio will not become brittle even in a wet and hot environment, and have good alkali resistance to the extent that the alkali content can be reduced. Furthermore, fibers that are completely biodegradable can be obtained when the content of polybutylene adipate terephthalate and polylactic acid is greater than that of polyethylene terephthalate. That is, the purpose of the present invention can be achieved by the following biodegradable fiber, which is characterized by comprising a fiber containing a blended polymer of polyethylene terephthalate, polybutylene adipate terephthalate and polylactic acid, wherein the content of polyethylene terephthalate in the fiber is at least 93% by mass, the content of polybutylene adipate terephthalate in the fiber is 0.4-2.4% by mass, the content of polylactic acid in the fiber is 0.4-2.4% by mass, and the content ratio of polybutylene adipate terephthalate and polylactic acid is 40/60-60/40 in terms of mass ratio.

In addition, in the above-mentioned biodegradable fiber, the content of polyethylene terephthalate in the fiber is 98% by mass or more, and the content ratio of polybutylene adipate terephthalate and polylactic acid is preferably 50/50 to 60/40 in terms of mass ratio (polybutylene adipate terephthalate/polylactic acid). In this way, a biodegradable fiber having higher resistance to wet and hot environments, biodegradability, and alkali resistance can be obtained. In addition, the biodegradability rate of the above-mentioned biodegradable fiber after 135 days in the ASTM D5511 test is preferably 15% or more.

In addition, the reduction rate of the breaking strength of the aforementioned biodegradable fiber after the following wet and hot environment test is preferably less than 25%. (Wet and hot environment test) A tube knit is produced, and a 120mm×150mm test piece is taken from the produced tube knit. After heat setting, the test is performed using the AG-IS Autograph (registered trademark) tensile testing machine manufactured by Shimadzu Corporation, with a sample width of 50mm, a test length of 50mm, and a constant tensile speed of 100mm/min. The maximum load value of the load-elongation curve is set as the breaking strength (cN), and the test pieces are measured twice in the warp knitting direction and the weft knitting direction, and the average value is set as the breaking strength before the wet and hot environment test. The test piece is measured using the AG-IS Autograph (registered trademark) tensile testing machine manufactured by Espec Corporation. The windless constant temperature/humidity testing machine PR-3KP was placed in a humid and hot environment with a temperature of 80°C and a relative humidity of 95%. After 400 hours, the breaking strength was measured twice by the above tensile test in the same way as before the humid and hot environment test. The average value was set as the breaking strength after the humid and hot environment test. The average value was used to calculate the reduction rate of the breaking strength in the humid and hot environment using the following formula. Fracture strength reduction rate in wet and hot environment (%) = {(fracture strength before wet and hot environment test - fracture strength after wet and hot environment test) / (fracture strength before wet and hot environment test)} × 100.

In addition, the mass reduction rate of the aforementioned biodegradable fiber after the following alkali resistance test is preferably 15% or less. (Alkaline resistance test) A 100mm×100mm test piece is taken from the produced woven tube, and the mass (W1) in the water balance state is measured. Then, it is immersed in a 4 mass% sodium hydroxide aqueous solution maintained at 98±2°C. After 30 minutes, the test piece is taken out, washed and dried, and then placed in a water balance state again, and the mass at this time is measured (W2). This measurement is performed twice, and the average value is used to calculate the mass reduction rate by the following formula. . [Invention Effect]

According to the present invention, a biodegradable fiber can be obtained which makes polyethylene terephthalate, which originally does not show biodegradability, also show biodegradability, and which has excellent alkali resistance and does not dissolve immediately when the alkali decreases, and is not easily brittle even in a wet and hot environment. In addition, the breaking strength and breaking elongation of the obtained biodegradable fiber are equivalent to those of polyethylene terephthalate fiber.

The biodegradable fiber of the present invention must have polyethylene terephthalate (hereinafter referred to as PET) as the main component, and includes a blended polymer containing polybutylene adipate terephthalate (hereinafter referred to as PBAT) and polylactic acid. By blending PBAT and polylactic acid into PET, the PET fiber that originally does not show biodegradability can be given biodegradability.

The biodegradable fiber of the present invention is biodegradable by the synergistic effect of the polylactic acid, a hydrolyzable material, being hydrolyzed in the high temperature and high humidity environment of the soil, utilizing the effect of promoting biodegradation by the action of microorganisms, and the direct microbial action of the PBAT, an enzyme-degradable material, being biodegradable.

The biodegradable fiber of the present invention preferably contains PET at least 93% by mass. The content of PET in the fiber is preferably 95% by mass or more. If the content of PET in the fiber is 93% by mass or more, the high breaking strength and alkali resistance of the fiber composed only of PET are not impaired, and the strength is not easily reduced in a humid and hot environment, so it can be used in the same applications as PET fiber.

The PET in the present invention is not only homopolymer PET, but also copolymer PET obtained by copolymerization with sulfoisophthalic acid metal salt.

In the PET of the present invention, for the purpose of improving various physical properties, modifiers such as light-resistant agents, heat-resistant agents, and matting agents may be added.

The content of PBAT in the present invention is preferably 0.4-2.4% by mass. It is preferably 0.6-2.2% by mass, and more preferably 0.8-2.0% by mass. If it is 0.4% by mass or more, PET can be given biodegradability. If it is 2.4% by mass or less, the alkali resistance is good, and the breaking strength and breaking elongation are not easily reduced.

The content of polylactic acid in the present invention is preferably 0.4-2.4% by mass, and preferably 0.6-2.2% by mass, and more preferably 0.8-2.0% by mass. If it is 0.4% by mass or more, it is easily hydrolyzed in the soil, and biodegradability can be imparted to PET. If it is 2.4% by mass or less, it is not easy to become brittle even in a wet and hot environment, has good alkali resistance, and the breaking strength and breaking elongation are not easy to decrease.

In the present invention, the content ratio of PBAT and polylactic acid is preferably 40/60 to 60/40 in terms of mass ratio. Moreover, it is preferably 45/55 to 55/45, and more preferably 48/52 to 52/48. When the content ratio is within the range of 40/60 to 60/40, the synergistic effect of PBAT and polylactic acid can be used to impart biodegradability to PET. Moreover, the strength is not easily reduced even in a humid and hot environment.

The biodegradability of the biodegradable fiber of the present invention after 135 days in the ASTM D5511 test is preferably 15% or more. It is more preferably 20% or more, and particularly preferably 25% or more. If the biodegradability after 135 days is 15% or more, sufficient biodegradability is shown. And the biodegradability of the biodegradable fiber of the present invention after 360 days in the ASTM D5511 test is preferably 35% or more. It is more preferably 40% or more, and particularly preferably 45% or more. The biodegradability of the biodegradable fiber of the present invention after 675 days in the ASTM D5511 test is preferably 57% or more. It is more preferably 60% or more, and particularly preferably 65% or more.

The reduction rate of the breaking strength of the biodegradable fiber of the present invention after the wet and hot environment test described below is preferably 25% or less. It is more preferably 15% or less, and particularly preferably 10% or less. If it is 25% or less, it can be used in applications that may become wet and hot environments, just like PET fibers.

The biodegradable fiber of the present invention preferably has a mass reduction rate of 15% or less after the alkali resistance test described below. If it is 15% or less, the texture can be appropriately improved by reducing the alkali content, similar to PET.

The total fiber density of the biodegradable fiber of the present invention is not particularly limited, and can be the same as the total fiber density used for conventional PET fibers. Based on the viewpoints of spinning operability and mechanical strength, it is preferably 1-300 dtex. If it is 1-100 dtex, it will maintain good texture when mainly used for clothing purposes. And, if it is 30-300 dtex, it will maintain good strength when used for vehicle purposes.

The preferred single yarn fineness of the biodegradable fiber of the present invention is 0.8-25 dtex. If it is 0.8 dtex or more, it can maintain good strength when mainly used for clothing. If it is 25 dtex or less, the specific surface area of the fiber is large and it is easy to biodegrade.

The breaking strength of the biodegradable fiber of the present invention is preferably 2.0 cN/dtex or more. It is more preferably 2.5 cN/dtex or more, and particularly preferably 3.0 cN/dtex or more. If it is 2.0 cN/dtex or more, it has good passing properties in the spinning operation and weaving step, and can be used in the same applications as PET fiber.

The elongation at break of the biodegradable fiber of the present invention is preferably 20% or more. If it is 20% or more, the fiber has good passing properties in the spinning operation and weaving process, and can be used in the same applications as PET fiber.

The biodegradable fiber of the present invention may be circular or have an irregular cross section. Examples of the irregular cross section include multi-lobed, triangular, flat, and elliptical.

The biodegradable fiber of the present invention can be used as long fibers, but can also be used as woven fabrics. In addition, the long fibers can be processed into short fibers, and can also be used as lining. It can also be used as non-woven fabrics. [Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the examples. In addition, the physical property measurements/evaluations in the examples were performed as follows.

(Tensile test) According to JIS L 1013, the AGS-1kNG Autograph (registered trademark) tensile tester manufactured by Shimadzu Corporation was used to measure the sample yarn length of 200 mm and the constant tensile speed of 200 mm/min. The value obtained by dividing the maximum load of the load-elongation curve by the fiber diameter is set as the breaking strength (cN/dtex), and the elongation at this time is set as the breaking elongation (%). The measurement was repeated 3 times and the average value was calculated.

(Biodegradability Evaluation) According to ASTM D5511 standard, an anaerobic biodegradability test at 52±2°C is carried out.

(Wet and hot environment test) A tube knitting machine (NCR-EW) (produced by Yingguang Industrial Co., Ltd.) was used to knit two yarns together to produce a tube with a warp of 30 yarns/inch and a weft of 37 yarns/inch. A 120mm×150mm test piece was taken from the produced tube and heat-set at 190℃ for 1 minute. Then, the tube was knitted using AG-IS manufactured by Shimadzu Corporation. Autograph (registered trademark) tensile testing machine was used for the test under the conditions of sample width 50mm, test length 50mm, and constant tensile speed 100mm/min. The maximum load value of the load-elongation curve was set as the breaking strength (cN). The warp knitting direction and weft knitting direction of the test piece were measured twice each, and the average value was set as the breaking strength before the wet and hot environment test. The windless constant temperature/constant humidity testing machine PR-3KP manufactured by Espec Co., Ltd. was used to place the test piece in a wet and hot environment with a temperature of 80℃ and a relative humidity of 95%. After 400 hours, the breaking strength of the warp knitting direction and weft knitting direction of the test piece was measured twice each, and the average value was set as the breaking strength after the wet and hot environment test. Use the following formula to calculate the reduction rate of fracture strength in a wet and hot environment. Reduction rate of fracture strength in a wet and hot environment (%) = {(fracture strength before wet and hot environment test - fracture strength after wet and hot environment test) / (fracture strength before wet and hot environment test)} × 100.

(Alkali resistance test) Use a tube knitting machine (NCR-EW) (produced by Yingguang Industrial Co., Ltd.) to knit with 2 combined yarns to produce a tube with 30 warps/inch and 37 wefts/inch. Take a 100mm×100mm test piece from the produced tube, measure the mass (W1) in the moisture balance state, and then immerse it in a 4 mass% sodium hydroxide aqueous solution maintained at 98±2℃. After 30 minutes, take out the test piece, wash and dry it, and then put it in the moisture balance state again, and measure the mass (W2) at this time. Perform this measurement twice, use the average value, and calculate the mass reduction rate by the following formula. The mass reduction rate is used as an indicator of alkali resistance. .

(Example 1) The blended polymer obtained by mixing 98 mass% PET, 1.0 mass% PBAT, 1.0 mass% polylactic acid, and 50/50 mass% PBAT to polylactic acid was melt-sprayed at 294°C and stretched to 3.1 times at 1350 m/min circumferential speed and 90°C temperature of GR1 and 4200 m/min circumferential speed and 140°C temperature of GR2 to produce 84 dtex/36f biodegradable fiber. The obtained biodegradable fiber was subjected to tensile test, biodegradability evaluation, wet and hot environment test, and alkali resistance test.

(Example 2) Biodegradable fiber was prepared in the same manner as in Example 1, except that the PBAT content was set to 1.1% by mass, the polylactic acid content was set to 0.9% by mass, and the PBAT and polylactic acid content ratio was mixed in a 55/45 mass ratio. The obtained biodegradable fiber was used to perform tensile test, biodegradability evaluation, wet and hot environment test, and alkali resistance test in the same manner as in Example 1.

(Example 3) Biodegradable fiber was prepared in the same manner as in Example 1, except that the PBAT content was set to 0.9 mass %, the polylactic acid content was set to 1.1 mass %, and the PBAT and polylactic acid content ratio was mixed in a 45/55 mass ratio. The obtained biodegradable fiber was used to perform tensile test, biodegradability evaluation, wet and hot environment test, and alkali resistance test in the same manner as in Example 1.

(Example 4) Biodegradable fiber was prepared in the same manner as in Example 1 except that the PET content was set to 96 mass%, the PBAT content was set to 2.0 mass%, and the polylactic acid content was set to 2.0 mass%. The obtained biodegradable fiber was used to perform the tensile test, biodegradability evaluation, wet and hot environment test, and alkali resistance test in the same manner as in Example 1.

(Example 5) Biodegradable fiber was prepared in the same manner as in Example 1, except that the PET content was set to 96% by mass, the PBAT content was set to 2.2% by mass, the polylactic acid content was set to 1.8% by mass, and the PBAT and polylactic acid content ratio was mixed in a 55/45 mass ratio. The obtained biodegradable fiber was used to perform tensile test, biodegradability evaluation, wet and hot environment test, and alkali resistance test in the same manner as in Example 1.

(Comparative Example 1) Except that only PET was used for melt spinning, multifilaments were prepared in the same manner as in Example 1. The obtained multifilaments were subjected to tensile tests, biodegradability evaluation, wet and hot environment tests, and alkali resistance tests in the same manner as in Example 1.

(Comparative Example 2) Except that only polylactic acid is melt-sprayed at 230°C, melt spinning is performed by a common method to produce 84dtex/36f multifilaments. The obtained multifilaments are used to perform tensile tests, biodegradability evaluation, and alkali resistance tests in the same manner as in Example 1. In addition, the heat setting temperature is set to 120°C, and the wet and hot environment tests,

(Comparative Example 3) Except that the PBAT content was set to 2.0 mass % and polylactic acid was not contained, multifilaments were prepared in the same manner as in Example 1. The obtained biodegradable fibers were used to perform tensile tests, biodegradability evaluation, wet and hot environment tests, and alkali resistance tests in the same manner as in Example 1.

(Comparative Example 4) Multifilaments were prepared in the same manner as in Example 1 except that PBAT was not contained and the polylactic acid content was set to 2.0 mass %. The obtained biodegradable fibers were used to perform tensile tests, biodegradability evaluation, wet and hot environment tests, and alkaline resistance tests in the same manner as in Example 1. These results are shown together in Table 1.

The results of the fiber property evaluation show that the PET fiber, which is almost non-biodegradable, shows excellent biodegradability for a long period of time when it contains both polylactic acid and PBAT (Example and Comparative Examples 1, 3, 4). In addition, from the results of each Example and Comparative Examples 3 and 4, it can be seen that the fiber of the Example can suppress the reduction of strength even when exposed to a high temperature and high humidity environment. Moreover, from the results of Comparative Example 2, it is confirmed that the fiber of the Example is a fiber with excellent alkali resistance because it contains PET as the main component. By making the PET content 97 mass% or more, it is confirmed that particularly excellent alkali resistance is obtained (Examples 1, 2, 3). Furthermore, it was confirmed that by setting the content ratio of PBAT/polylactic acid to 1 or more, particularly excellent alkali resistance was obtained (Examples 2 and 3, 4 and 5). Furthermore, it can be seen that in the case of Examples 1 and 2, the breaking strength after the wet and hot environment test can be suppressed to a particularly low level of 4% or less, and the biodegradability is also excellent. As shown in Table 1, Examples 1 to 5 show sufficient biodegradability. Moreover, the strength is fully maintained even in a wet and hot environment, and the alkali resistance is also excellent. Moreover, the breaking strength and breaking elongation are not reduced, and are equivalent to PET. The obtained biodegradable fiber is suitable as a fiber for clothing and a fiber for automotive interior materials.

Comparative Example 1 has no reduction in strength in a hot and humid environment and shows high alkali resistance, but does not show biodegradability. Comparative Example 2 has excellent biodegradability, but its strength is significantly reduced in a hot and humid environment. In addition, it has poor alkali resistance and completely dissolves after immersion in a sodium hydroxide aqueous solution for 10 minutes. Comparative Examples 3~4 have poor biodegradability, and the biodegradation rate after 135 days in the ASTM D5511 test does not reach 15%. [Industrial Applicability]

Although the biodegradable fiber of the present invention shows biodegradability after hydrolysis in soil, it can be appropriately used in automotive interior materials that can be used in high temperature environments, because its strength is only slightly reduced even in a humid and hot environment. In addition, it is also excellent in alkali resistance, so it can be reduced in alkali like PET fiber to improve its texture, so it can be appropriately used in clothing applications, for example. In addition, it can also be appropriately used in industrial materials, daily materials, etc., which are the same as the uses of ordinary PET fibers.

Claims (6)

A biodegradable fiber comprising a blended polymer of polyethylene terephthalate, polybutylene adipate terephthalate and polylactic acid, wherein the content of the polyethylene terephthalate in the fiber is 80% by mass or more. A biodegradable fiber, comprising a blended polymer containing polyethylene terephthalate, polybutylene adipate terephthalate and polylactic acid, wherein the content of the polyethylene terephthalate in the fiber is at least 93% by mass, the content of the polybutylene adipate terephthalate in the fiber is 0.4-2.4% by mass, the content of the polylactic acid in the fiber is 0.4-2.4% by mass, and the content ratio of the polybutylene adipate terephthalate to the polylactic acid is 40/60-60/40 by mass. The biodegradable fiber of claim 1 or 2, wherein the content of the polyethylene terephthalate in the fiber is 98% by mass or more, and the content ratio of the polybutylene adipate terephthalate to the polylactic acid is 50/50 to 60/40 by mass. For biodegradable fibers as claimed in claim 1 or 2, the biodegradability rate after 135 days in the ASTM D5511 test is 15% or more. For biodegradable fibers as claimed in claim 1 or 2, the reduction rate of breaking strength after the following wet heat environment test is less than 25%. (Wet heat environment test) Make a tube knitted fabric, take a 120mm×150mm test piece from the produced tube knitted fabric, heat-set it, and use AG-IS Autograph (registered trademark) tensile testing machine manufactured by Shimadzu Corporation to measure the test piece under the conditions of sample width 50mm, test length 50mm, and constant speed tensile speed 100mm/min. The maximum load value of the load-elongation curve is set as the breaking strength (cN). The test piece is measured twice in the warp knitting direction and the weft knitting direction respectively, and the average value is set as the breaking strength before the wet heat environment test. Use Espe c Co., Ltd., placed in a humid and hot environment with a temperature of 80°C and a relative humidity of 95%. After 400 hours, the breaking strength of the test piece in the warp knitting direction and the weft knitting direction were measured twice each, and the average value was set as the breaking strength after the humid and hot environment test. Using these average values, the following formula was used to calculate the reduction rate of the breaking strength in the humid and hot environment. Reduction rate of breaking strength in the humid and hot environment (%) = {(breaking strength before the humid and hot environment test - breaking strength after the humid and hot environment test) / (breaking strength before the humid and hot environment test)} × 100. For the biodegradable fiber of claim 1 or 2, the mass reduction rate after the following alkali resistance test is 15% or less. (Alkali resistance test) A 100 mm × 100 mm test piece is taken from the produced woven fabric, and the mass (W1) in the water balance state is measured. Then, the test piece is immersed in a 4 mass% sodium hydroxide aqueous solution maintained at 98±2°C. After 30 minutes, the test piece is taken out, washed and dried, and then the water balance state is set again. The mass at this time (W2) is measured. The mass reduction rate is calculated by the following formula using the average value of the two measurements. .