JP2011157646A - Polyester microfiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microfiber that is formed from a sea-island type conjugate fiber having excellent yarn manufacturing properties and island component formation properties during elution, has strength and uniformity and overcomes problems of conventional technology. <P>SOLUTION: The polytrimethylene terephthalate microfiber satisfies that (a) the microfiber has an average single fiber diameter of 50-2,000 nm, a CV% of an average single fiber diameter of 0-25% and a strength of 1.5-6.0 cN/dtex, (b) the microfiber is a microfiber obtained by eluting the sea component of the sea-island type conjugate fiber comprising a polytrimethylene terephthalate as an island component and (c) the sea component is a copolyester of a polyethylene glycol-based compound and 5-sodium sulfoisophthalic acid and is a polyester in which the amount of the polyethylene glycol-based compound copolymerized is 5-12 wt.% based on the total weight of the polyester and the amount of the 5-sodium sulfoisophthalic acid copolymerized is 5-8 mol% based on the total acid component of the polyester. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ultrafine polytrimethylene terephthalate fiber having flexibility and strength, and excellent handleability and aesthetics.

  Conventionally, ultrafine fibers have been used in industrial materials such as clothing fabrics, artificial leather, and filters in order to exhibit flexibility, aesthetics, and denseness. As materials for ultrafine fibers, polyamides such as nylon 6 and nylon 66 and polyesters such as polyethylene terephthalate are generally used. However, the ultrafine fiber made of polyamide has poor weather resistance due to the inherent properties of this material and has disadvantages such as yellowing. On the other hand, the ultrafine fiber made of polyethylene terephthalate has excellent weather resistance but is similar to nylon 6. There is no flexibility, and it has been desired to have both light resistance and flexibility.

In order to solve such a problem, an ultrafine multifilament made of polytrimethylene terephthalate (Patent Document 1) can be used. However, this method is a method by direct yarn production, and there is a limit to the fineness to be obtained, and the productivity. There is also a problem in processability.
On the other hand, as a method for producing polytrimethylene terephthalate ultrafine fibers, for example, Patent Document 2 discloses polytrimethylene terephthalate ultrafine yarns obtained by eluting sea components from sea-island fibers. However, in this case as well, the fineness is as thick as 0.01 to 0.5 dtex, which is insufficient in terms of flexibility and denseness for industrial materials.

  Patent Document 3 proposes a sea-island composite fiber having a number of islands of 100 or more per sea-island fiber as a method for obtaining polyester ultrafine fibers. Certainly, this method can obtain very fine polytrimethylene terephthalate, but it is not sufficient for industrial materials, and the formation of island components is poor, so uniformity cannot be obtained when polished, and polytrimethylene terephthalate is There has been a problem that it is difficult to crystallize oriented polyethylene terephthalate and it is difficult to ensure strength.

Therefore, in the case of sea-island fibers with polytrimethylene terephthalate as an island component for industrial materials, it is necessary that the sea component be compatible with both the solubility removability, the strength of the obtained ultrafine fibers, and the yarn production. There was a need to select a limited one.
As described above, in the conventional method, there are still problems in securing processability and fiber strength when the polytrimethylene terephthalate is further miniaturized.

Japanese Patent No. 3199669 JP 2006-265786 A WO2005 / 095686

  An object of the present invention is to provide a polytrimethylene terephthalate microfiber having a strength and uniformity and a fabric including the same, which is formed from a sea-island type composite fiber excellent in yarn-forming property and island component formation at the time of elution. It is in.

  As a result of investigations to solve such problems, the present inventors have used a polyester polymer obtained by copolymerizing a specific component in a sea-island type composite fiber containing polytrimethylene terephthalate as an island component as a sea component. The object was achieved because the ultrafine fibers comprising the components could be made uniform and high in physical properties.

That is, according to the present invention,
A polyester ultrafine fiber whose main repeating unit is trimethylene terephthalate, which satisfies the following requirements:
a) The ultrafine fiber has an average single fiber diameter of 50 to 2000 nm, an average single fiber diameter of 0 to 25%, and a strength of 1.5 to 6.0 cN / dtex.
b) The ultrafine fiber is an ultrafine fiber obtained by elution treatment of a sea component of a sea-island type composite fiber containing polytrimethylene terephthalate as an island component.
c) The sea component is a polyester obtained by copolymerizing 5-sodium sulfoisophthalic acid with 5 mol% or more of the total polyester acid component and 5% or more of the polyethylene glycol compound with respect to the total weight of the polyester.
Is provided.

  The polyester microfiber of the present invention can be processed into any form of fiber, spun yarn, and non-woven fabric, and since it is soft, uniform and excellent in strength, as described above, including industrial materials, It can be suitably used for clothing and medical applications.

Hereinafter, the polyester microfiber of the present invention will be described in detail.
The polyester microfiber of the present invention is a polyester obtained by using polytrimethylene terephthalate, which is a polyester whose main repeating unit is trimethylene terephthalate, and having terephthalic acid as the main acid component and 1,3-propanediol as the main glycol component. is there. As used herein, “main” refers to containing 80 mol% or more, and includes a copolymer component capable of forming another ester bond at a ratio of 20 mol% or less within a range not impairing the effects of the present invention. It may be a thing. The copolymerizable compound includes dicarboxylic acids such as isophthalic acid, cyclohexanedicarboxylic acid, adipic acid, dimer acid, sebacic acid and 2,6-naphthalenedicarboxylic acid, and glycol components such as ethylene glycol and diethylene glycol. , Butanediol, neopentyl glycol, cyclohexane dimethanol, polyethylene glycol, polypropylene glycol and the like, but are not limited thereto.
Further, various additives such as matting agents, heat stabilizers, flame retardants, antistatic agents, lubricants, color pigments, antifoaming agents, and the like may be copolymerized or mixed as necessary.

The polytrimethylene terephthalate used in the present invention can be polymerized by a known method.
The polyester ultrafine fiber of the present invention preferably has an intrinsic viscosity of 0.8 to 2.0. When the intrinsic viscosity is less than 0.8, mechanical properties such as strength are deteriorated and wear resistance is inferior. When the intrinsic viscosity is more than 2.0, ultrafine fibers cannot be stably produced. A more preferable intrinsic viscosity is 0.9 to 1.5.

  Moreover, the average single yarn diameter of the polyester microfiber of the present invention is required to be 50 to 2000 nm. If it is less than 50 nm, the strength of the total fiber is lowered and it is difficult to use it as an industrial material, and if it exceeds 2000 nm, sufficient flexibility and expression of performance as an ultrafine yarn are lowered. A preferred range is 300-1500 nm.

  Furthermore, CV% of the average fiber diameter of the polyester microfiber of the present invention is 0 to 25%. When CV% exceeds 25%, the variation in diameter is large and the performance of the ultrafine fiber is markedly lowered, more preferably 0 to 20%, still more preferably 0 to 15%. Since the ultrafine fiber of the present invention has a small CV% and a small variation in diameter, it is possible to control the fiber diameter of the fine single fiber at the nano level and to design a product suitable for the application. For example, in filter applications, if a substance that can be adsorbed at a fine single fiber diameter is selected, the fiber diameter can be designed according to the application, and product design can be performed very efficiently. Become.

  The strength of the polyester ultrafine fiber of the present invention is required to be 1.5 to 6.0 cN / dtex as the tensile strength when the ultrafine fiber is measured as a fiber bundle. If the tensile strength is 1.5 cN / dtex, the application is limited and it is difficult to put it to practical use. Moreover, the fiber exceeding 6.0 cN / dtex is not preferable in consideration of the balance with the elongation in the production process. A more preferable range is 1.8 to 5.5 cN / dt. The elongation at break is preferably 10 to 80%, and the shrinkage in boiling water is preferably 5 to 20%.

  As a method for producing the polyester ultrafine fiber of the present invention, a conventionally known method can be mentioned, but a method of producing by removing sea components from a multi-island structure sea-island composite fiber is most preferable. In this case, the sea component polymer can be appropriately selected as long as it is a combination having higher solubility than the island component polymer, but the dissolution rate ratio (sea / island) is preferably 200 or more. When this dissolution rate ratio is less than 200, part of the island component of the fiber cross-section surface layer is dissolved while the sea component of the fiber cross-section center is dissolved, so the sea component is completely dissolved and removed. In order to do so, the island component will be reduced by a percentage, resulting in deterioration of the strength due to unevenness of the thickness of the island component and solvent erosion, resulting in fluff and pilling, etc. is there.

  When sea component removal by alkali elution is performed, the sea component polymer is, for example, an alkaline aqueous solution easily soluble polymer, and is compatible with both easy alkali solubility and sea-island cross-sectional formability. It is necessary to copolymerize sulfoisophthalic acid in an amount of 5 to 8 mol%, preferably 6 to 8 mol%, based on the total polyester acid component. Further, polyethylene glycol having a number average molecular weight of 4000 to 12000 is copolymerized in an amount of 5 to 12% by weight, preferably 5 to 10% by weight, based on the total weight of the polyester. The intrinsic viscosity of the sea component is preferably 0.4 to 0.6. Here, 5-sodium isophthalic acid contributes to improving the hydrophilicity and melt viscosity of the resulting copolymer, and polyethylene glycol (PEG) improves the hydrophilicity of the resulting copolymer.

  The definition of the copolymerization amount is important for obtaining the polyester ultrafine fiber of the present invention, and 5-sodium isophthalic acid is 5 to 8 mol%, preferably 6 to 8%, based on the total acid components constituting the polyester. It must be mol%. If it exceeds 8 mol%, the yarn-making property is remarkably lowered and stable production becomes difficult, and a product having a predetermined strength cannot be obtained. If it is less than 5 mol%, the difference in dissolution rate from polytrimethylene terephthalate is not sufficient. Elimination of sea components is impossible. On the other hand, polyethylene glycol is required to be 5 to 12% by weight, preferably 6 to 10% by weight, based on the total sea component polyester weight. When the copolymerization amount of polyethylene glycol exceeds 12% by weight, polyethylene glycol originally has a melt viscosity lowering action and a plasticizing action, so that the fiber cross-section formability becomes difficult, and if it is less than 5% by weight, the stability of the spinning process In particular, the stretchability is lowered, it is difficult to ensure strength, and it is difficult to dissolve only the sea components. Therefore, it is preferable to copolymerize both components within the above range.

  The sea-island type composite fiber composed of the sea component polymer and the island component polymer preferably has a sea component melt viscosity higher than that of the island component polymer during melt spinning. In such a relationship, even if the composite mass ratio of the sea components is as low as less than 40%, the islands are joined together, or the sea island type sea island where most of the island components are joined together. A cross-sectional shape different from the mold is not formed. A preferable melt viscosity ratio (sea / island) is 1.1 to 2.0, and more preferably 1.3 to 1.5. If this ratio is less than 1.1 times, the island components can be easily joined to each other at the time of process stable melt spinning, whereas if it exceeds 2.0 times, the viscosity difference is too large and spinning is performed. The stability of the process tends to decrease.

  Next, the greater the number of island components, the higher the productivity when producing ultrafine fibers by dissolving and removing sea components, and the resulting ultrafine fibers are also significantly thinner, with the softness and smoothness unique to ultrafine fibers. In addition, since glossiness and the like can be expressed, it is important that the number of island components is 100 or more, and preferably 500 or more. Here, when the number of island components is less than 100, high multifilament yarns composed of ultrafine fibers cannot be obtained even if sea components are dissolved and removed, and the object of the present invention cannot be achieved. If the number of island components is too large, not only the manufacturing cost of the spinneret increases, but also the processing accuracy of the spinneret itself tends to decrease. Therefore, the number of island components is preferably 1000 or less.

  Furthermore, the sea-island composite fiber of the present invention preferably has a sea-island composite mass ratio (sea: island) in the range of 40:60 to 5:95, particularly in the range of 30:70 to 10:90. It is preferable that it exists in. If it exists in the said range, the thickness of the sea component between island components can be made thin, the dissolution removal of a sea component will become easy, and the conversion to an ultrafine fiber of an island component will become easy. Here, when the proportion of the sea component exceeds 40%, the thickness of the sea component becomes too thick. On the other hand, when the proportion is less than 5%, the amount of the sea component becomes too small and the mutual connection occurs between the islands. It becomes easy.

  The sea component and the island component are melted separately, combined into a sea-island shape in the base, and discharged. Then, after solidifying with cooling air or the like, the undrawn fiber is taken up at a speed of preferably 400 to 6000 m / min, more preferably 1000 to 3000 m / min. A lower spinning speed is preferable because higher fiber strength is obtained, but productivity is insufficient at 400 m / min or less, and spinning stability is poor at 6000 m / min or more.

  The obtained unstretched fiber is stretched by any one of a method of winding it once or after winding through a stretching process without winding. The drawing temperature is 60 to 90 ° C, preferably 70 ° C to 80 ° C, preheated on a preheating roller and drawn at a draw ratio of 1.1 to 6.0 times, preferably 1.2 to 5.0 times. It is preferable to carry out heat setting at 120 to 180 ° C, preferably 130 to 160 ° C. If it is a slit type heater, 180-220 degreeC is used preferably. In the case where the preheating temperature is insufficient, the intended high-strength drawing cannot be achieved. If the set temperature is too low, the shrinkage rate of the obtained drawn fiber is too high, which is not preferable. On the other hand, if the set temperature is too high, the physical properties of the obtained drawn fiber are remarkably lowered, which is not preferable.

  In the present invention, in order to produce a sea-island type composite fiber having a particularly fine island component diameter with high efficiency, the fiber structure is generally prior to neck stretching (orientation crystallization stretching) with so-called orientation crystallization. It is also possible to adopt a fluid drawing process in which only the fiber diameter is refined without being changed. Specifically, the drawn composite fiber is immersed in a hot water bath in the range of 60 to 100 ° C., preferably in the range of 60 to 80 ° C. and uniformly heated, while the draw ratio is 10 to 30 times and the supply speed is 1 to 10 m. / Min, the winding speed is 300 m / min or less, and it is particularly preferable to carry out the pre-flow stretching in the range of 10 to 300 m / min.

  The polytrimethylene terephthalate ultrafine fiber of the present invention can produce the above-mentioned sea-island type composite fiber by the following method. That is, after weaving a woven fabric having a specific cover factor and thickness, for example, a sea-island type composite fiber in which the island component is made of polytrimethylene terephthalate and the diameter of the island component is 50 to 2000 nm, an alkaline aqueous solution treatment is performed, By dissolving and removing the sea component of the sea-island type composite fiber with an alkaline aqueous solution using a known alkali weight loss device, an ultrafine fiber bundle having a single fiber diameter of 50 to 2000 nm can be obtained.

  In order to remove the sea component, it is preferable to treat with an aqueous solution of an alkali metal compound such as sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate, among which sodium hydroxide and potassium hydroxide are particularly preferably used. The concentration, treatment temperature, and treatment time of the aqueous alkali solution vary depending on the type of alkali compound used, but the concentration is 10 to 300 g / L, the temperature is 40 ° C. to 180 ° C., and the treatment time is in the range of 2 minutes to 20 hours. Is preferred.

  Applications of the polytrimethylene terephthalate ultrafine fibers of the present invention include intermediate products such as braided yarns, spun yarns made of short fibers, woven fabrics, knitted fabrics, felts, and nonwoven fabrics. In addition, interior products such as carpets, sofas and curtains, vehicle interior products such as car seats, cosmetics, cosmetic masks, wiping cloths, health products, etc. using these, abrasive cloths, filters, harmful substance removal products, Environment / industrial material applications such as battery separators, medical applications such as sutures, scaffolds, artificial blood vessels, blood filters, and clothing such as jackets, skirts, pants, and underwear, sports clothing, and clothing materials . We can provide textile products that combine the softness and flexibility of polytrimethylene terephthalate with the feel of ultrafine fibers.

The invention is further illustrated by the following examples.
In the following examples and comparative examples, the following measurements and evaluations were performed.
(1) Average single yarn fiber diameter The fiber diameter was determined by TEM observation 30000 times the fine fiber after sea component dissolution and removal. Here, the fiber diameter of the single yarn that was not glued was measured. In the fiber diameter data of 100 randomly selected fine fibers, the average single yarn fiber diameter r was calculated.
(2) Average single fiber diameter variation CV%
When determining the average single yarn fiber diameter, the standard deviation σ was calculated, and the fiber diameter variation coefficient CV% defined below was calculated.
CV% = standard deviation σ / average single yarn fiber diameter r × 100 (%)
(3) Tubular knitting was made from high-strength sea-island composite fibers, and sea components were eluted with an alkaline solution to make ultrafine fiber bundles. This ultrafine fiber bundle was measured for strength at break and elongation under conditions of a sample length of 20 cm and a speed of 20 cm / min with a tensile tester in an atmosphere of 20 ° C. and 65% RH. The number of measurements was 10, and the average value of strength was calculated using the fineness determined from the average single yarn fiber diameter, and the strength (cN / dtex) was obtained.
(4) Process stability Spinnability, stretchability, and weight loss were evaluated as follows.
Spinnability: Spinning was performed for 48 hours, ◯ when the yarn was broken or troubled 0 to 1 times, Δ when the yarn was broken several times, and × when the winding was impossible in several hours.
Stretchability: When the composite fiber obtained by spinning is stretched and heat-set, ○ when there is almost no fluff or breakage, △ when breakage is observed several times, and the process is unstable and impossible Was marked with x.
Weight loss: Treated in an alkaline solution and observed the cross section of the fiber with SEM, ○ that can remove only the sea component is ○, and that that could not find the weight loss condition that can remove only the sea component is × did.

[Example 1]
Polytrimethylene terephthalate having an intrinsic viscosity of 0.96 (35 ° C. in orthochlorophenol) as an island component, and 6 mol% of 5-sodium sulfoisophthalic acid and 6% by weight of polyethylene glycol having a number average molecular weight of 4000 as a sea component were copolymerized. Polyethylene terephthalate with an intrinsic viscosity of 0.54 was melted separately and joined in a composite die. A sea-island composite unstretched fiber with sea: island = 30: 70 and island number = 836 was spun at a spinning temperature of 270 ° C. It was melt-spun at a speed of 1500 m / min and wound up. Spinning was carried out for 48 hours, but no breakage was observed. The obtained undrawn yarn was roller-drawn at a drawing temperature of 80 ° C. and a draw ratio of 3.5 times, and then heat-set with a non-contact heater at 220 ° C. to obtain a sea-island type composite drawn yarn. In the drawing process, no fluff or yarn breakage occurred, and all undrawn yarns could be drawn without problems. The obtained sea-island type composite drawn yarn was 56 dtex / 10 fil, and a tubular knitting was prepared. When the weight was reduced in an alkaline solution at 90 ° C. and 3.5 g / l, only the sea component was eluted. The average fiber diameter was 710 nm, CV% was 12%, the strength was 2.2 cN / dtex, and the elongation was 61%.

[Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 3]
A sea-island composite fiber was obtained in the same manner as in Example 1 using a sea polymer having the composition shown in Table 1 as the sea component. Table 1 shows the physical properties of the ultrafine yarn obtained by elution from the obtained sea-island type composite fiber.
As shown in Table 1, in Examples 1 and 2, there were no problems in spinnability, stretchability, and weight loss, and ultrafine fibers with excellent strength and uniformity could be obtained.
As the composition of the sea polymer, Comparative Example 1 in which the copolymerization amount of 5-sodium sulfoisophthalic acid was increased and the copolymerization amount of polyethylene glycol was decreased was poor in both spinnability and stretchability and poor in stability for production. -In Comparative Examples 2 and 3 in which the copolymerization amounts of sodium sulfoisophthalic acid and polyethylene glycol were reduced, the weight loss was poor, and ultrafine fibers could not be obtained.

  The polytriethylene terephthalate microfiber of the present invention is used for interior products such as carpets, sofas, curtains, vehicle interior products such as car seats, cosmetics, cosmetic masks, wiping cloths, health products, etc. For environmental and industrial material applications such as substance removal products and battery separators, medical applications such as sutures, scaffolds, artificial blood vessels and blood filters, and clothing such as jackets, skirts, pants and underwear, sports clothing, and clothing materials Can be used.

Claims (1)

A polyester ultrafine fiber whose main repeating unit is trimethylene terephthalate, which satisfies the following requirements.
a) The ultrafine fiber has an average single fiber diameter of 50 to 2000 nm, an average single fiber diameter of 0 to 25%, and a strength of 1.5 to 6.0 cN / dtex.
b) The ultrafine fiber is an ultrafine fiber obtained by elution treatment of a sea component of a sea-island type composite fiber containing polytrimethylene terephthalate as an island component.
c) The sea component is a copolymerized polyester of a polyethylene glycol compound and 5-sodium sulfoisophthalic acid, the polyethylene glycol compound is 5 to 12% by weight based on the total weight of the polyester, and 5-sodium sulfoisophthalic acid is the total acid of the polyester. It is a polyester copolymerized with 5 to 8 mol% with respect to the component.