JP5655632B2 - Sea-island composite cross-section fiber made of alkali-eluting polyester - Google Patents

Description

  The present invention relates to a sea-island type composite cross-section fiber.

  Polyamide fiber typified by polycaproamide and polyhexamethylene adipamide, and polyester fiber typified by polyethylene terephthalate and polybutylene terephthalate are excellent in mechanical properties and dimensional stability. Widely used in interior and industrial applications.

  When melt-spinning ultra-fine fibers for the purpose of imparting adsorptive properties (hygroscopicity, water absorption, deodorant properties, etc.) and softness to the fibers, the spinneret design should be used for fibers with a single yarn diameter of micron. It can also be obtained by melt spinning with a single polymer focusing on the main point, but for ultrafine fibers, composite spinning with a readily soluble polymer to obtain a composite cross-section fiber, dissolving and removing the easily soluble polymer It is the mainstream to get.

  For example, a composite cross-section fiber composed of polyamide and aliphatic polyester, in which at least a part of the aliphatic polyester is arranged to be exposed on the fiber surface, a fabric is obtained from the composite cross-section fiber, and the aliphatic polyester is obtained from the fabric. A method of dissolving and removing to obtain polyamide ultrafine fibers is disclosed (Patent Document 1). In addition, after obtaining a sea-island type composite cross-section fiber with polylactic acid as a sea component and polyamide as an island component, and having an island diameter and a uniform island interval, the sea component is dissolved and removed from the composite cross-section fiber to obtain a fiber diameter. Discloses a method for obtaining uniform polyamide ultrafine fibers (Patent Document 2). However, since the methods described in Patent Documents 1 and 2 are a combination of polymers that are poorly compatible with polyamide and easily peel off at the interface, generation of fluff due to peeling at the sea-island composite interface in the yarn-making process in this method. There was a problem.

  In obtaining a sea-island-type composite cross-sectional fiber suitable for obtaining a polyamide ultrafine fiber, a combination of an easily soluble polymer that is incompatible with the polyamide described in Patent Document 1 or a simple island diameter described in Patent Document 2 is used. It was extremely difficult to suppress peeling at the sea-island composite interface in the yarn forming process only by a method that specified uniformity and distribution of island components. Therefore, a sea-island type composite cross-sectional fiber suitable for obtaining a polyamide ultrafine fiber that can be stably melt-spun and has good high-order passability is desired.

JP 2000-54228 A JP 2009-74211 A

  The present invention can suppress peeling of the composite interface at the time of yarn production, which has been a problem due to the poor affinity with the island component polyamide for the polyester conventionally used as a sea component, and greatly reduces fluff, yarn breakage, etc. It is an object of the present invention to provide a sea-island-type composite cross-sectional fiber that can be improved and an ultrafine polyamide fiber obtained by dissolving and removing the polyester contained in the sea-island composite fiber.

In order to solve the above problems, the present invention adopts the following configuration.
(1) The main repeating unit is composed of ethylene terephthalate, the isophthalic acid component containing a metal sulfonate group is 2.0 to 5.5 mol% based on the total acid component, and the adipic acid component is 3.0 to A sea-island type composite cross-section fiber containing 6.0 mol% of an alkali-eluting polyester as a sea component and polyamide as an island component.
(2) The sea-island type composite as described in (1) above, wherein the alkali-elutable polyester containing 3 to 10 ppm of a titanium compound soluble in polyester and containing 5 to 40 ppm of phosphorus compound in terms of phosphorus element is used. Cross-section fiber.
(3) The sea-island composite cross-section fiber according to (1) or (2), wherein the weight ratio of the polyester to the polyamide is in the range of 5:95 to 40:60.
(4) Any of the above (1) to (3), wherein the elongation is 30 to 50%, and the number of fluffs per 10,000 m length of the fiber yarn is 0 to 2 The sea-island type composite cross-section fiber described in 1.
(5) A fabric having at least a part of the sea-island composite cross-section fiber according to any one of (1) to (4).
(6) An ultrafine polyamide fiber formed by dissolving and removing the polyester by subjecting the sea-island type composite cross-section fiber according to any one of (1) to (4) to an alkali treatment.
(7) A fabric having at least a portion of the ultrafine polyamide fiber according to (6).
(8) A fiber product having at least a part of the ultrafine polyamide fiber according to (6).

  According to the present invention, peeling of the composite interface during yarn production can be suppressed, and fluff, yarn breakage, and the like can be significantly improved.

  In addition, the polyester contained in the sea-island type composite cross-section fiber of the present invention is obtained by copolymerizing an isophthalic acid component containing a metal sulfonate group, and further copolymerizing an adipic acid component, thereby improving alkali elution. The elution rate is fast and industrially advantageous.

  By dissolving and removing the polyester contained in the sea-island type composite cross-section fiber of the present invention to obtain a polyamide ultrafine fiber, it is possible to obtain excellent characteristics not found in conventional synthetic fibers. In particular, a fabric having an excellent soft feeling and a good touch can be obtained, and since the fiber specific surface area is increased, an ultrafine polyamide fiber excellent in adsorption performance, for example, hygroscopicity can be obtained.

1 is a schematic view of a sea-island type composite spinneret used in Examples and Comparative Examples of the present invention.

  The sea-island type composite cross-sectional fiber of the present invention is a sea-island type composite cross-sectional fiber in which an alkali-eluting polyester is a sea component and polyamide is an island component.

  The polyamide used in the present invention is a resin composed of a high molecular weight substance in which a so-called hydrocarbon group is connected to the main chain through an amide bond, and such a polyamide has excellent dyeability and mechanical properties, and is an alkali. It is preferably composed mainly of polycaproamide (nylon 6), which is suitable for composite melt spinning with easily eluting polyester. The term “mainly” as used herein means that ε-caprolactam units constituting polycaproamide are 80 mol% or more in all monomer units, and more preferably 90 mol% or more. Examples of other components include, but are not limited to, polydodecanoamide, polyhexamethylene adipamide, polyhexamethylene azelamide, polyhexamethylene sebamide, polyhexamethylene dodecanoamide, polymetaxylylene adipa Examples thereof include units such as aminocarboxylic acid, dicarboxylic acid, and diamine, which are monomers constituting imide, polyhexamethylene terephthalamide, polyhexamethylene isophthalamide and the like.

  In addition, the degree of polymerization of the polyamide is the required characteristics of the sea-island composite cross-section fiber, the polyamide ultra-fine fiber fiber obtained by dissolving and removing the alkali-eluting polyester contained in the sea-island composite cross-section fiber, or a processed product thereof, or In order to obtain them stably, it may be appropriately selected from an appropriate range, but it is preferably in the range of 2.0 to 3.6 in terms of 98% sulfuric acid relative viscosity at 25 ° C., more preferably 2.4 to The range is 3.3.

  The polyester used for the sea component of the sea-island composite cross-section fiber of the present invention is based on polyethylene terephthalate obtained after esterification or transesterification of dicarboxylic acid or its ester-forming derivative and diol or its ester-forming derivative. And

  The polyethylene terephthalate contains 2.0 to 5.5 mol% of an isophthalic acid component containing a metal sulfonate group with respect to the total acid component, and 3.0 to 6.0 mol% of an adipic acid component with respect to the total acid component. It is a leachable polyester.

  It is essential for the alkali-eluting polyester to contain 3.0 to 6.0 mol% of the adipic acid component with respect to the total acid component in order to have alkali elution and affinity with polyamide. More preferably, it is 4.0-5.5 mol%. When it is less than 3.0 mol%, the color tone and heat resistance of the resulting polyester are good, but peeling at the composite interface occurs, and the elution to alkali is also reduced. If the amount is more than 6.0 mol%, the heat resistance of the resulting polyester is inferior, so that the yarn-making property is deteriorated.

  Adipic acid or an ester-forming derivative of adipic acid is used as the monomer constituting the adipic acid component in the alkali-eluting polyester. For example, as the adipic acid-forming derivative, adipic acid-forming derivatives such as methyl ester, ethyl ester, isopropyl ester, and ethylene glycol ester can be used. The adipic acid component is preferably adipic acid or dimethyl adipate from the viewpoint of easy procurement of raw materials.

  It is essential for the alkali-elutable polyester to contain 2.0 to 5.5 mol% of isophthalic acid containing a metal sulfonate group with respect to the total acid component in order to have good alkali elution. More preferably, it is 2.0 mol% to 3.0 mol%. When the amount is less than 2.0 mol%, the color tone and heat resistance of the resulting polyester are good, but the elution property to alkali decreases. When it is more than 5.5 mol%, the heat resistance of the resulting polyester is inferior, so that the yarn-making property is deteriorated.

  As the monomer for forming an isophthalic acid component containing a metal sulfonate group of an alkali-eluting polyester, a known isophthalic acid component containing a metal sulfonate group can be used. Dimethyl isophthalate.

  The alkali-eluting polyester preferably contains 3 to 10 ppm of a titanium compound soluble in the polyester in terms of titanium element. More preferably, it is 4-8 ppm. If it is less than 3 ppm, the polymerization reaction activity is insufficient, the reaction is delayed, and the resulting polyester is colored yellowish. If it exceeds 10 ppm, the activity of the polymerization reaction is good, but the color tone and heat resistance of the polyester obtained due to the high activity deteriorate.

  The titanium compound soluble in the alkali-eluting polyester is preferably a titanium complex. Examples of the chelating agent that forms the complex include polyhydric alcohols, polycarboxylic acids, hydroxycarboxylic acids, and nitrogen-containing carboxylic acids. These are preferably used, and one or more of them are preferably used from the viewpoint of the color tone and heat resistance of the obtained polyester.

  Specific examples of titanium compound chelating agents soluble in alkali-eluting polyesters include polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, mannitol, and the like. Acid, trimellitic acid, trimesic acid, hemititic acid, pyromellitic acid and the like, hydroxycarboxylic acid includes lactic acid, malic acid, tartaric acid, citric acid, and the like, and nitrogen-containing carboxylic acid includes ethylenediaminetetraacetic acid, nitrilolic acid. Tripropionic acid, carboxyiminodiacetic acid, carboxymethyliminodipropionic acid, diethylenetriamino acid, triethylenetetraminohexaacetic acid, iminodiacetic acid, iminodipropionic acid, hydroxyethyliminodiacetic acid, hydroxyethyliminodipropionic acid, methoxye Ruimino diacetate, and the like. These titanium compounds may be used alone or in combination. Titanium oxide generally used in fibers and the like is not soluble in polyester and is therefore excluded from the titanium compound referred to in the present invention.

  The alkali-eluting polyester preferably contains 5 to 40 ppm of a phosphorus compound in terms of phosphorus element. More preferably, it is 9-35 ppm. If the amount is less than 5 ppm in terms of phosphorus element, an adipic acid component and an acidic isophthalic component containing a metal sulfonate group are copolymerized, so that the decomposition reaction of the polyester is easily promoted, and the color tone and heat resistance of the resulting polyester deteriorate. If the amount is more than 40 ppm in terms of phosphorus element, the polymerization reaction catalyst is deactivated, the polymerization reaction activity is lowered, the polymerization reaction is delayed, and the resulting polyester is colored yellowish.

  As a phosphorus compound, the phosphorus compound represented by (Formula 1)-(Formula 5) can be used. When the phosphonite compound represented by (Formula 1) or (Formula 2) and the phosphate compound represented by (Formula 3) are used, an adipic acid component and an isophthalic acid component containing a metal sulfonate group are copolymerized. Regardless, the alkali-eluting polyester is preferable in terms of further improving the color tone during melt spinning and excellent heat resistance.

(In the above (Formula 1), R1 and R2 each independently represents a hydroxyl group or a hydrocarbon group having 1 to 20 carbon atoms.)

(In the above (Formula 2), R1 to R4 each independently represents a hydroxyl group or a hydrocarbon group having 1 to 20 carbon atoms.)

(In the above (Formula 3), R1 to R3 each independently represents a hydrocarbon group having 1 to 20 carbon atoms.)

  The coloring of the polyester and the deterioration of heat resistance are caused by a side reaction of the polyester polymerization reaction as clearly shown in the saturated polyester resin handbook (Nikkan Kogyo Shimbun, first edition, P.178 to P.198). In the side reaction of this polyester, carbonyl oxygen is activated by a metal catalyst, and β hydrogen is extracted, thereby generating a vinyl end group component and an aldehyde component. The polyene is formed by this vinyl end group, so that the polyester is colored yellow, and the main chain ester bond is cleaved because the aldehyde component is generated, so that the polyester has poor heat resistance. In particular, when the polyester skeleton has an adipic acid component or an isophthalic acid component containing a metal sulfonate group, coordination to carbonyl oxygen easily occurs by a metal catalyst, β-hydrogen is easily extracted, and vinyl terminal Machine components and aldehyde components are likely to be generated. Due to the formation of polyene by this vinyl end group, the polyester is colored yellowish, and since an aldehyde component is generated, the main chain ester bond is easily cleaved, so that the polyester has poor heat resistance and color tone. It becomes.

  Further, when a titanium compound is used as a polymerization catalyst, since the side reaction due to heat is strongly activated, a large amount of vinyl end group components and aldehyde components are generated, resulting in a yellowish colored polyester having poor heat resistance. The phosphorus compound not only plays a role in regulating the activity of the polymerization catalyst by appropriately interacting with the polymerization catalyst, but also distributes the titanium compound to the carbonyl oxygen of the isophthalic acid component containing an adipic acid component or a metal sulfonate group. Make it difficult to occur.

  When the phosphonite compound of (Formula 1) or (Formula 2) and the phosphate compound of (Formula 3) of the alkali-eluting polyester are used, the heat resistance and color tone of the polyester are greatly improved while sufficiently maintaining the polymerization activity of the titanium compound. Therefore, it is preferable.

  Among these, when a phosphorus compound represented by the following (formula 4) is used, the color tone and heat resistance of the polyester are excellent.

(In the above (Formula 4), R5 to R7 each independently represents a hydroxyl group or a hydrocarbon group having 1 to 10 carbon atoms. The hydrocarbon group is an alicyclic structure, an aliphatic branched structure, an aromatic group. (It may contain one or more group structures, hydroxyl groups and double bonds, and a + b + c = 0 to 5 is an integer.)

  Examples of the phosphorus compound represented by the above (formula 4) include, for example, a compound in which a is 2, b is 0, c is 0, R5 is a tert-butyl group, and R5 is a 2,4-position. -Di-tert-butylphenyl) [1,1-biphenyl] -4,4'-diylbisphosphonite, and this compound is IRGAFOS P-EPQ (manufactured by Ciba Specialty Chemicals) or Sandostab P-EPQ ( Available from Clariant Japan).

  Among these, a phosphorus compound represented by (Formula 5) is preferable because the color tone and heat resistance of the obtained polyester are particularly good.

(In the above (Formula 5), R8 to R10 each independently represents a hydroxyl group or a hydrocarbon group having 1 to 10 carbon atoms. The hydrocarbon group is an alicyclic structure, an aliphatic branched structure, an aromatic group. One or more group structures, hydroxyl groups and double bonds may be included.)

  As the phosphorus compound represented by the above (formula 5), R8 is a tert-butyl group, R9 = tert-butyl group, and R10 is a methyl group. Tetrakis (2,4-di-t-butyl-5 -Methylphenyl) [1,1-biphenyl] -4,4'-ylbisphosphonite, and this compound is available as GSY-P101 (Osaki Kogyo).

  Furthermore, as a phosphorus compound represented by (Formula 3), it is preferable that R1 to R3 are all trimethyl phosphates which are methyl groups because the color tone and heat resistance of the resulting polyester are improved. This compound is available as TMP (manufactured by Daihachi Chemical).

  The alkali-eluting polyester preferably does not substantially contain an element having a true specific gravity of 5 or more. The element having a true specific gravity of 5 or more is, for example, an antimony element generally used as a polymerization catalyst, or a cobalt element or a manganese element generally used as a transesterification catalyst.

  “Substantially free” means that the content is 10 ppm or less, preferably 5 ppm, more preferably 3 ppm or less.

  In addition, a well-known additive can be contained in the range which does not impair the objective of this invention. For example, a by-product inhibitor of diethylene glycol (hereinafter referred to as DEG) such as tetraethylammonium hydroxide (hereinafter referred to as EAH) or lithium acetate (hereinafter referred to as LAH), a transesterification catalyst represented by a metal acetate such as magnesium acetate, A radical scavenger represented by IR1010 and a matting agent represented by titanium oxide. In particular, the content of EAH is preferably 125 ppm or less, more preferably 40 ppm or less in terms of nitrogen.

  The content of LAH is preferably 15 to 70 ppm as lithium element, and more preferably 25 to 55 ppm. These by-product inhibitors of DEG can be used in combination.

  Magnesium acetate used as the transesterification reaction catalyst is preferable because the true specific gravity of the magnesium element is 5 or less. The content is preferably 40 ppm to 100 ppm, more preferably 50 ppm to 90 ppm, as magnesium element.

  In addition, you may contain the titanium oxide used as a matting agent, and in order to implement spinning of the obtained polyester stably, it can contain to 2.5 wt% as a titanium oxide density | concentration.

  The sea-island composite cross-sectional fiber of the present invention may contain various additives as long as the effects of the present invention are not impaired. Examples of this additive include stabilizers such as manganese compounds, colorants such as titanium oxide, flame retardants, conductivity imparting agents, and fibrous reinforcing agents.

  The weight ratio of the alkali-elutable polyester and the polyamide contained in the sea-island composite cross-section fiber of the present invention is obtained by dissolving and removing the alkali-elutable polyester contained in the sea-island composite cross-sectional fiber and the sea-island composite cross-sectional fiber. The required properties of the polyamide ultrafine fiber, or processed product thereof, or an appropriate range for obtaining them stably may be appropriately selected, but preferably 5:95 to 40 by weight ratio of the alkali-eluting polyester to polyamide. : 60, and more preferably in the range of 10:90 to 50:50. If the weight ratio between the alkali-elutable polyester and the polyamide is less than 15:95, the polyamide which is an island component is easily fused with each other during melt spinning. Therefore, when the alkali-elutable polyester is dissolved and removed, it has a uniform fiber diameter. It becomes difficult to obtain polyamide ultrafine fibers. In addition, when the weight ratio between the alkali-eluting polyester and the polyamide exceeds 40:60, the amount of solvent necessary for dissolving and removing the alkali-eluting polyester increases. It is not preferable also from a viewpoint. In addition, since the polyamide ultrafine fiber itself obtained by dissolving and removing the alkali-eluting polyester is too thin compared to the sea-island type composite cross-section fiber before dissolution and removal, the fabric density becomes too rough when it is made into a fabric or the like. The fabric design of the textile product may become difficult, and the product variation may be reduced.

With respect to the fiber cross section of the sea-island type composite cross-section fiber of the present invention, when the single yarn is divided into four equal parts by drawing two straight lines that pass through the center of the single yarn cross section of the fiber and are orthogonal to each other, When the area variation (Scv) of the sea component of the part is represented by the following relational expression, the following Scv is preferably small.
Scv = Sstd / Sx × 100
(However, Sx represents the area average value of the four sea components, and Sstd represents the standard deviation (square root of unbiased variance) of the area of the four sea components.)

  About Scv, Preferably it is the range of 0-25, More preferably, it is the range of 0-20. The purpose of this range is the uniform dispersion of the polyamide, which is an island component, and by suppressing the fusion of the polyamides due to the localized bias of the polyamide, when the aliphatic polyester is dissolved and removed, the uniform fiber diameter is reduced. It is possible to obtain polyamide ultrafine fibers. Further, when viewed in the fiber cross section, since the stress is evenly distributed in the fiber cross section, it is possible to obtain, for example, a sea-island type composite cross section fiber with less variation in strength and elongation in the fiber longitudinal direction.

  When Scv exceeds 25, the polyamide which is an island component is locally biased, the polyamides are fused at the time of melt spinning, and when the alkali-eluting polyester is dissolved and removed, it has a uniform fiber diameter. It becomes difficult to obtain polyamide ultrafine fibers. Moreover, it becomes a fiber with many strong elongation variations in a fiber longitudinal direction.

Regarding the fiber cross section of the sea-island type composite cross-section fiber of the present invention, with respect to all the islands arranged on the outermost periphery of the single yarn cross section of the fiber, the distance variation (Rcv) between each island and the outermost periphery of the single yarn is as follows: As a relational expression, the following Rcv is preferably small.
Rcv = Rstd / Rx × 100
(However, Rx represents an average value of the distance between each island disposed on the outermost periphery and the outermost periphery of the single yarn, and Rstd represents a standard deviation (unbiased) between each island disposed on the outermost periphery and the outermost periphery of the single yarn. (The square root of dispersion.) The distance between each island arranged on the outermost periphery and the outermost periphery of the single yarn is expressed by the shortest linear distance from the center of the island to the outermost periphery of the fiber.)

  About Rcv, Preferably it is the range of 0-30, More preferably, it is the range of 0-20. The purpose of this range is to obtain a uniform polyamide ultrafine fiber, and to obtain a sea-island type composite cross-section fiber with little variation in strength and elongation in the longitudinal direction of the fiber, as described above.

  When Rcv exceeds 30, when the polyamide which is an island component arranged on the outermost periphery is locally biased, the polyamides are fused together at the time of melt spinning, and the alkali-eluting polyester is dissolved and removed. A polyamide ultrafine fiber having a uniform fiber diameter cannot be obtained. Moreover, it becomes a fiber with many strong elongation variations in a fiber longitudinal direction.

  The single yarn fineness of the polyamide ultrafine fiber obtained by dissolving and removing the alkali-eluting polyester of the sea-island composite cross-section fiber of the present invention is preferably in the range of 0.01 to 0.5 dtex, and more preferably Is in the range of 0.01 to 0.2 dtex. When the single yarn fineness of the polyamide ultrafine fiber is less than 0.01 dtex, stable melt spinning including the yarn quality becomes difficult.

  Generally, when thinning the single yarn fineness of polyamide ultrafine fibers, there are methods such as increasing the total number of islands per spinneret or decreasing the discharge rate of polyamide per spinneret, but the total number of islands per spinneret If the amount is too large, there is a problem in that, as described above, when the alkali-eluting polyester is dissolved and removed, polyamide ultrafine fibers having a uniform fiber diameter cannot be obtained. In addition, if the discharge amount of the polyamide per spinneret is too low, it becomes difficult to measure the melted polyamide in the spinneret, and the polyamide ultrafine fiber having a uniform fiber diameter is obtained when the alkali-eluting polyester is dissolved and removed. The problem remains that you can no longer get.

  Polyamide ultrafine fibers having a single yarn fineness of more than 0.5 dtex can be obtained by single melt spinning with a single polymer focusing on the spinneret design, so there is no merit obtained as a sea-island type composite cross-section fiber.

  The sea-island composite cross-section fiber of the present invention can be obtained as a fiber product as it is, but by dissolving and removing the alkali-elutable polyester contained in the sea-island composite cross-section fiber by alkali, it has excellent soft feeling and adsorption performance. It is possible to obtain a very fine polyamide fiber. Furthermore, it is also possible to obtain new added values such as glossiness and tactile sensation by partially dissolving and removing the alkali-eluting polyester contained in the sea-island type composite cross-section fiber. In these cases, the fabric obtained from the sea-island composite cross-section fiber is treated with alkali. Examples of the alkali here include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like, but strong alkalis (pH = 10-14) such as sodium hydroxide, potassium hydroxide and the like are 0.5-20. It is preferable to process at 60-120 degreeC as weight% aqueous solution.

  The fiber product using the sea-island type composite cross-section fiber of the present invention, and the fiber product using the polyamide ultrafine fiber obtained by dissolving and removing the alkali-elutable polyester contained in the sea-island type composite cross-sectional fiber are camisole. , Innerwear such as shorts, leg knits such as stockings and socks, sports and casual wear such as shirts and blousons, pants, coats, apparel materials such as men's and women's apparel, as well as apparel materials such as bra cups and pads, It can also be suitably used for interior applications such as curtains, carpets, mats and furniture, industrial material applications such as water-absorbing felts and polishing cloths, industrial material applications such as filters, and vehicle interior applications.

  The manufacturing method of the sea-island type composite cross-section fiber of the present invention will be described. The sea-island type composite cross-section fiber of the present invention can be produced by any known method, but from the viewpoint of sea-island composite formability, productivity, and cost, production by melt spinning is most excellent. Regarding the production method by melt spinning, a method in which the spinning-stretching process is continuously performed (direct spinning stretching method), a method in which the unstretched yarn is wound once and then stretched (two-step method), or a spinning speed is 3000 m / min or more. Thus, it can be produced by any method such as a method (high speed spinning method) that substantially eliminates the drawing step at a high speed, and yarn processing such as false twisting or air entanglement may be performed as necessary.

  Examples of production by the direct spinning drawing method will be described below.

  First, the melting part will be described. In melting the polyamide and the alkali-eluting polyester, a pressure melter method or an extruder method can be mentioned, but both are not particularly limited. The melting temperature is preferably 240 to 280 ° C. in the case of polyamide, and preferably 270 to 290 ° C. for the alkali-elutable polyester.

  The polyamide and the alkali-eluting polyester that have flowed into the spinning pack are joined together by a known spinneret, formed into a sea-island composite cross section, and discharged from the spinneret. There are various known examples of the sea-island composite spinneret, but the sea island in the spinneret is provided with a plurality of pipes that serve as island component channels and sea component channels (slits) surrounding each of these island components. Complex formation is preferable because Scv and Rcv can be easily controlled. This will be described in detail with reference to FIG. FIG. 1 is an example of a sea-island type composite spinneret that can be used in the present invention, and is a schematic view showing a cross section of a sea-island type composite spinneret used in examples described later. The island component flowing in from the island component inflow hole (pipe) (5) passes through the gap (6) to the slit (7) between the sea component inflow hole (4) to the first plate (1) and the second plate (2). According to the sea component which passed, it will become the form coated in a so-called junction part (8). The island components coated with the sea component merge at the junction (9) of the No. 3 plate (3), are formed in a sea-island composite section, and are discharged from the discharge hole (10). In order to obtain a good sea-island composite cross-section satisfying Scv and Rcv, it is particularly necessary to sufficiently measure the sea component, and there are 2 pipes in the island component inflow hole (pipe) (5) as shown in FIG. A spinneret that has entered the middle of the plate (2) is more preferable because the length of the slit (7) necessary for measuring sea components can be obtained.

  Further, the spinning temperature (so-called temperature keeping temperature around the polymer pipe or spinning pack) is preferably 240 to 280 ° C.

  The sea-island type composite cross-section fiber discharged from the spinneret is cooled and solidified, and after an oil agent is applied, it is taken up. The take-up speed is preferably in the range of 1000 to 5000 m / min, the draw ratio is appropriately set so that the elongation of the drawn yarn is in the range of 30 to 50%, and 1 goded roll is 80 to 100 ° C., 2 goded rolls are 150 to It is preferable to set a heat setting temperature in the range of 180 ° C., perform stretching and heat treatment, and wind up at a speed of 3000 to 5000 m / min. In addition, it is possible to perform entanglement using a known entanglement device in the process up to winding. If necessary, the number of confounding can be increased by giving a plurality of times. Furthermore, it is also possible to add an oil agent immediately before winding.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example at all unless the summary is exceeded. Moreover, the measuring method of the physical property of the sea-island type composite cross-section fiber and polyamide ultrafine fiber of the present invention is as follows.

A. Intrinsic viscosity of polyester IV
The sample was dissolved in orthochlorophenol and measured at 25 ° C. using an Ostwald viscometer.

B. Polyester color tone A color difference meter (manufactured by Suga Test Instruments Co., Ltd., SM color computer model SM-T45) was used to measure as a Hunter value (b value). In batch polymerization, the color tone of polyester sampled in half the time in terms of weight in the discharge process is used.

C. Δ Intrinsic viscosity 280 (index indicating heat resistance)
After the polyester was dried under reduced pressure at 150 ° C. for 12 hours and then heated and melted at 280 ° C. for 60 minutes in a nitrogen atmosphere, the intrinsic viscosity was measured by the method A, and the difference before and after heating and melting was designated as Δ intrinsic viscosity 280. Calculated.

D. DEG content in polyester The polyester was thermally decomposed with monomethanolamine, diluted with 1,6 hexanediol / methanol, neutralized with terephthalic acid, and then determined from the peak area of gas chromatography.

E. Content of Titanium Element, Phosphorus Element and the like in Polyester Elemental analysis of contained metals such as phosphorus element and magnesium element was performed using a fluorescent X-ray elemental analyzer (manufactured by Horiba, Ltd., MESA-500W type).

  In addition, about the fixed_quantity | quantitative_assay of the titanium element soluble in polyester, the titanium compound insoluble in polyester was removed by performing the next pre-processing, and the fluorescent X ray analysis was performed. That is, polyester is dissolved in orthochlorophenol (5 g of polyester with respect to 100 g of solvent), and after adding the same amount of dichloromethane as this polyester solution to adjust the viscosity of the solution, a centrifuge (rotation speed 18000 rpm, 1 hour) To settle the particles. Thereafter, only the supernatant liquid is collected by the gradient method, and the polyester is reprecipitated by adding the same amount of acetone as the supernatant liquid, and then filtered through a 3G3 glass filter (manufactured by IWAKI). After washing with, the acetone was removed by vacuum drying at room temperature for 12 hours. The polyester obtained by the above pretreatment was analyzed for titanium element.

F. 98% sulfuric acid relative viscosity (ηr) of polyamide
The number of seconds at 25 ° C. of the following solution was measured with an Ostwald viscometer and calculated according to the following formula. When 98% concentrated sulfuric acid (T1) and 98% concentrated sulfuric acid (T2) in which polycaproamide is dissolved to 1 g / 100 ml are used,
(Ηr) = T1 / T2.

G. Spinning property The yarn breakage per t when producing a composite fiber yarn or the like was shown according to the following criteria.
A: Less than 2 yarn breaks (excellent in yarn production),
B: Thread breakage 2 to less than 4 times,
C: Yarn break 4 or more and less than 6 times,
D: Thread breakage 6 to less than 8 times,
E: Thread breakage of 8 or more (inferior in yarn production).

H. Fiber cross-sectional observation with an optical microscope Cut out a thin section of about 6 microns by, for example, hardening the fiber with wax in the fiber crossing direction, and cross the fiber with an optical microscope (80iTP-DPH-S manufactured by Nikon Corporation). The surface was observed. When observing the entire fiber yarn, the magnification was 1000 times, and when observing a single yarn, it was 3000 times, and the observation magnification was changed as necessary to observe the fiber cross section.

I. Scv
The fiber cross-sectional photograph by the optical microscope (3000 times) described above was obtained using image processing software (WINROOF manufactured by Mitani Corporation). Details are as follows.
(1) Five single yarns were randomly selected from a fiber cross-sectional photograph.
(2) For each single yarn, two straight lines passing through the center and perpendicular to each other by 90 degrees were drawn to divide the single yarn into four equal parts.
(3) About each single yarn, the area of four sea components was measured by WINROOF, and the area average value (Sx) and standard deviation (Sstd) were calculated. The standard deviation was calculated from unbiased variance.
(4) For each single yarn, Scv was calculated from the relational expression of Scv = Sstd / Sx × 100, and the average value was calculated from the Scv of each single yarn.

J. et al. Rcv
The fiber cross-sectional photograph by the optical microscope (3000 times) described above was obtained using image processing software (WINROOF manufactured by Mitani Corporation). Details are as follows.
(1) Five single yarns were randomly selected from a fiber cross-sectional photograph.
(2) For each single yarn, the shortest linear distance between the center of all the islands arranged on the outermost periphery and the outermost outer periphery of the single yarn was measured with WINROOF, and the average value (Rx) and standard deviation (Rstd) were calculated. . The standard deviation was calculated from unbiased variance.
(3) For each single yarn, Rcv was calculated from the relational expression of Rcv = Rstd / Rx × 100, and the average value was calculated from the Rcv of each single yarn.

K. Elongation (1) Elongation (S) conformed to Section 8.5 of JIS L1013 (1999). In addition, as measurement conditions, a constant-speed tension type testing machine (Tensilon manufactured by Orientec Co., Ltd.) was used, and the grip interval was 50 cm and the tensile speed was 50 cm / min.

L. Using a multi-point fluff counting device (MFC-120 manufactured by Toray Engineering Co., Ltd.), fibers were unwound from the fiber package at 600 m / min, measured for 10,000 m, and the number of fluff displayed on the device was counted. In addition, warp cloth (made of stainless steel, 1 mm spacing) was provided before the measurement point, and the fiber was passed therethrough. 50 packages selected at random were evaluated all at once, and the average number was evaluated.

M.M. Alkali-eluting properties Four pieces of fabric pieces (20 cm × 20 cm) after weaving were prepared and treated with 20 g / l sodium hydroxide aqueous solution at 95 ° C. (temperature rising 2 ° C.), 30 minutes, 60 minutes, 90 minutes, 120 The weight loss rate of polyethylene terephthalate when taken out every minute is measured. The time required for the weight loss rate to reach 90% or more is shown by the following criteria.
◎: 30 minutes or less,
○: More than 30 minutes and less than 60 minutes Δ: More than 60 minutes and less than 90 minutes ×: More than 90 minutes or insoluble removal

  The synthesis | combining method of the titanium compound used in the following Example is shown.

(Ti-lactic acid catalyst)
In a reaction tank purged with nitrogen, 536.4 g of lactic acid (manufactured by Wako Pure Chemical Industries, Ltd.) is added to 40 L of ethylene glycol as a reaction solvent and heated to 80 ° C. Then, after cooling to 40 degreeC, 712g of titanium tetraisopropoxide (made by Nippon Soda) was added, and it stirred for 24 hours. Thus, a Ti-lactic acid catalyst (titanium content: 2.63 g / L) was obtained.

(Ti-mannitol catalyst)
456.8 g of mannitol (manufactured by Tokyo Kasei Co., Ltd.) is added to 40 L of ethylene glycol as a reaction solvent in a nitrogen-substituted reaction tank, and heated to 80 ° C. to dissolve. Then, after cooling to 40 degreeC, 712g of titanium tetraisopropoxide (made by Nippon Soda) was added, and it stirred for 24 hours. Thus, a Ti-mannitol catalyst (titanium content: 2.63 g / L) was obtained.

[Example 1]
(Polymerization method)
In a transesterification reaction tank equipped with a rectifying column, 927 parts by weight of dimethyl terephthalate, 595 parts by weight of ethylene glycol, and a concentration of 5.1 mol% with respect to all acid components in the polyester from which dimethyl adipate is obtained. Preparation was carried out so that dimethyl 5-sodium sulfoisophthalate was obtained in an amount of 2.4 mol% based on the total acid components in the polyester. Thereafter, the Ti-lactic acid catalyst is 5 ppm in terms of titanium element, and tetrakis (2,4-di-t-butyl-5-methylphenyl) [1,1-biphenyl] -4,4′-diylbisphosphonite as a phosphorus compound. (GSY-P101 manufactured by Osaki Industrial Chemical Co., Ltd.) was added to 10 ppm in terms of phosphorus element, magnesium acetate tetrahydrate was added to 600 ppm, and then EAH20 (tetraethylammonium hydroxide 20%, water 67%, A methanol 13% mixture (manufactured by Sanyo Chemical) was added at 1200 ppm (29.3 ppm in terms of nitrogen). Thereafter, the temperature of the transesterification reaction tank was gradually raised, and the reaction was allowed to proceed while distilling off methanol generated during the transesterification reaction out of the reaction system to obtain a low polymer. Thereafter, the low polymer was transferred from the transesterification reaction tank to the polymerization reaction tank. After completion of the liquid transfer, an ethylene glycol slurry of titanium oxide was added so that the concentration in the polyester was 0.07 wt%. After 5 minutes, the temperature in the reaction vessel was gradually raised from 240 ° C. to 280 ° C., and the pressure was reduced to 50 Pa while distilling off ethylene glycol. When the predetermined agitator torque (power value) was reached, the reaction system was purged with nitrogen to return to normal pressure, the polymerization reaction was stopped, discharged in a strand form, cooled, and immediately cut to obtain polyester pellets. The time from the start of decompression to the arrival of the predetermined agitator torque was approximately 2 hours and 15 minutes. The obtained polyester had an intrinsic viscosity of 0.62, DEG 2.0 wt%, b value 14.0, Δ intrinsic viscosity 280 of 0.015, and was excellent in color tone and heat resistance.

(Spinning method)
This polyester chip was dried by a conventional method so that the moisture content was 0.01% by weight or less. Further, as a polyamide layer, a nylon 6 chip having a sulfuric acid relative viscosity (ηr) of 2.6 was dried by a conventional method so that the moisture content was 0.05% by weight or less.

  Polyester chips at 270 ° C., nylon 6 chips at a melting temperature of 270 ° C., 20% by weight of the polyethylene terephthalate chip and 80% by weight of nylon 6 chips (in the weight ratio shown in Table 1). Then, it was melted in a spinning pack, joined to a spinning pack and a die, formed into a sea-island composite, and discharged from the spinning die. The spinneret is a spinneret in which the pipe (5) shown in FIG. 1 has entered partway through the No. 2 plate (2). There are 37 islands per single yarn (hole) and the number of holes per spinneret. Of 20 (total number of islands is 740). The spinning temperature was 270 ° C. After discharging from the spinneret, cooling with 18 ° C. cold air and refueling, it was stretched 2.20 times and wound at a winding speed of 4000 m / min to obtain a 78 dtex-20 filament sea-island type composite cross-section fiber. . With the obtained split split fiber type composite fiber, the island part circumscribed circle diameter (μm) and the sea island part area ratio were evaluated. In the terephthalate polyethylene terephthalate layer, a circumscribed circular 0.3 μm island was present at an island area ratio of 20% of the sea island.

(Evaluation method)
The obtained sea-island type composite cross-section fibers were evaluated for Scv, Rcv, strong elongation product, strong elongation product variation, and number of fluff. Regarding the spinning operability, the number of spun yarn breakage when 1 t of sea-island type composite cross-section fiber was produced was evaluated. In addition, the softness of plain woven fabric made of polyamide ultrafine fibers obtained by dissolving and removing the polyester of the obtained sea-island type composite cross-section fibers by the method described above was also evaluated. These results are shown in Table 1.

[Examples 2 to 8]
It implemented by the same method as Example 1 except having set it as the conditions of Tables 1 and 3. All of them were excellent in yarn production and alkali elution, and the obtained sea-island composite fiber was good with almost no fluffing.

[Examples 9, 10, 12, 13]
It implemented by the same method as Example 1 except having set it as the conditions of Tables 2 and 4. Although all were inferior in yarn-making property compared with Examples 1-8, they were excellent in alkali elution, and the obtained sea-island composite fiber was good with little occurrence of fluff.

Example 11
It implemented by the same method as Example 1 except having set it as the conditions of Tables 2 and 4. Although it was inferior to the yarn forming property as compared with Examples 1 to 8, it was excellent in alkali elution and almost free from fluff.

[Comparative Examples 1, 3, 5]
The same method as in Example 1 was performed except that the conditions described in Tables 5 and 6 were used. All were excellent in yarn-making property, and when the content of adipic acid in the obtained sea-island composite fiber was reduced, the fluff increased and the alkali elution was inferior.

[Comparative Examples 2, 4, 6]
The same method as in Example 1 was performed except that the conditions described in Tables 5 and 6 were used. All were excellent in alkali elution, and the obtained sea-island composite fiber was good with little occurrence of fluff, but was inferior in yarn-making property.

[Comparative Example 7]
The same method as in Example 1 was performed except that the conditions described in Tables 5 and 6 were used. The resulting sea-island composite fiber was excellent in yarn-making property, and fuzz frequently occurred, and the alkali elution property was inferior.

[Comparative Example 8]
The same method as in Example 1 was performed except that the conditions described in Table 7 were used. The affinity between the sea component polylactic acid and the island component nylon 6 was poor, and fluff was generated.

[Comparative Example 9]
The same method as in Example 1 was performed except that the conditions described in Table 7 were used. Due to the difference in viscosity between the polylactic acid, which is a sea component, and nylon 6, which is an island component, the island components are fused together, resulting in a complex abnormality.

表１、２の結果から明らかなように、本発明の海島型複合断面繊維は、従来の海島型複合断面繊維と比較して、ポリアミド極細繊維の剥離による高次工程での毛羽が大幅に改善されており、紡糸操業性が良好で、アルカリに対しても優れた溶解性を示す、極めて顕著な効果を奏するものであると言える。また、好ましい態様においては、さらに紡糸操業性をさらに改善した海島型複合繊維が得られ、実用性をさらに向上させることができる。

As is clear from the results in Tables 1 and 2, the sea-island composite cross-section fiber of the present invention has significantly improved fluff in the higher-order process due to the peeling of the polyamide ultrafine fiber compared to the conventional sea-island composite cross-section fiber. Therefore, it can be said that the spinning operability is good and the solubility to the alkali is excellent, and a very remarkable effect is exhibited. Moreover, in a preferred embodiment, a sea-island type composite fiber with further improved spinning operability can be obtained, and the practicality can be further improved.

1: No. 1 plate 2: No. 2 plate 3: No. 3 plate 4: Sea component inflow hole 5: Island component inflow hole (pipe)
6: 1 No. plate (1) and No. 2 plate (2) gap 7: slit 8, 9: junction 10: discharge hole

Claims (8)

The main repeating unit is composed of ethylene terephthalate, the isophthalic acid component containing a metal sulfonate group is 2.0 to 5.5 mol% based on the total acid component, and the adipic acid component is 3.0 to 6.0 based on the total acid component. A sea-island type composite cross-section fiber comprising a sea component of an alkali-eluting polyester and an island component of polyamide. The sea-island-type composite cross-section fiber according to claim 1, wherein an alkali-eluting polyester containing 3 to 10 ppm of a titanium compound soluble in polyester in terms of titanium element and 5 to 40 ppm in terms of phosphorus element of phosphorus compound is used. The sea-island type composite cross-section fiber according to claim 1 or 2, wherein the weight ratio of the polyester to the polyamide is in the range of 5:95 to 40:60. The sea-island composite according to any one of claims 1 to 3, wherein the elongation is 30 to 50% and the number of fluffs per 10,000 m of the fiber yarn is 0 to 2 Cross-section fiber. A fabric having at least a portion of the sea-island type composite cross-section fiber according to any one of claims 1 to 4. An ultrafine polyamide fiber formed by dissolving and removing polyester by subjecting the sea-island type composite cross-section fiber according to any one of claims 1 to 4 to an alkali treatment. A fabric having at least a portion of the ultrafine polyamide fiber according to claim 6. A fiber product having at least a part of the ultrafine polyamide fiber according to claim 6.

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