JP2020026599A - Water-repellent ultrafine fiber bundle and fabric comprising water-repellent ultrafine fiber bundle - Google Patents

Abstract

To provide an ultrafine fiber filament bundle having excellent water repellency even without undergoing a water-repellent post-processing treatment.SOLUTION: A water-repellent ultrafine fiber bundle is provided which comprises a thermoplastic resin having a surface tension of 40 mN/m or less. The single fiber diameter of fibers comprising the thermoplastic resin is 50 to 1500 nm and the coefficient CV of variation of the fiber diameter is 30% or less. A fabric is also provided which comprises the water-repellent ultrafine filament bundle.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to an ultrafine fiber bundle having excellent water repellency and a fabric using the ultrafine fiber bundle without particularly performing post-water repellency processing.

2. Description of the Related Art Conventionally, it has been widely practiced to treat a cloth with a dispersion liquid containing a fluorine-based resin or a silicone-based resin, attach the resin to the cloth surface, and perform a water-repellent treatment. However, although the fabrics obtained by these processings have water repellency, if the treatment is performed in an amount sufficient to impart sufficient water repellency, the texture of the fabrics becomes hard and, therefore, sports Application to fields where both water repellency and feeling are required, such as wear and casual wear, has been greatly limited. In addition, soft water-repellent fibers having a fine-textured texture are obtained by using only a resin having water-repellency and hydrophobicity. On the other hand, conventional methods for producing ultrafine fibers using such a resin are limited to melt blowing, electrospinning, and the like (JP-A-2005-29931, JP-A-2015-124255), and nonwoven fabric sheet production methods. There has been a demand for a fiber bundle having excellent water repellency without performing post-water repellency processing so that various processes such as wet nonwoven fabric can be performed.

JP 2009-56765 A JP 2005-29931 A JP 2015-124255 A

  The present invention has been made in view of the above background, and an object of the present invention is to provide an ultrafine fiber long fiber bundle having excellent water repellency without performing post-water repellency processing.

As a result of intensive studies to solve the above problems, the present invention has been achieved. That is, according to the present invention,
1. The surface tension is made of a thermoplastic resin having a surface tension of 40 mN / m or less, and the fiber made of the thermoplastic resin has a single fiber diameter of 50 to 1500 nm, and a variation rate CV of the fiber diameter is 30% or less. It is a water-repellent ultrafine fiber bundle.
According to the present invention, it has been found that a fiber bundle having excellent water repellency can be provided without performing post-water repellency processing.
Preferably, the present invention employs the following configuration.
2. The above-mentioned water-repellent ultrafine fiber bundle comprising a water-repellent ultrafine fiber having a contact angle of 120 ° or more.
Then, in order to solve the above-mentioned problem, the following fabric is adopted.
3. A cloth comprising the water-repellent ultrafine fiber bundle of 1 or 2.

  According to the present invention, a water-repellent ultrafine fiber bundle and a water-repellent ultrafine fiber bundle that have excellent water repellency without being subjected to post-water repellent processing and are excellent in various processes such as woven, knitted, and wet nonwoven fabrics are also used. Can be provided.

FIG. 1 is a schematic view of a spinneret used for spinning the sea-island composite fiber of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail.

  The present invention is directed to a sea-island composite fiber in which a thermoplastic resin having a surface tension of 40 mN / m or less in a sea component in a cross section of a composite fiber is present in a number of islands and continuously present in the fiber axis direction. A water-repellent ultrafine fiber bundle made of yarn is produced. And the water-repellent ultrafine fiber bundle has a single yarn fiber diameter of the thermoplastic resin fiber of 50 to 1500 nm and a variation rate CV of the fiber diameter of 30% or less.

(Sea-island type composite fiber)
First, the sea-island composite fiber of the present invention is formed of a thermoplastic polymer having a surface tension of 40 mN / m or less, preferably 1 to 35 mN / m or less, measured according to JIS K 6768, after being formed into a film having a thickness of 20 μm. And an island component having an island diameter of 50 to 1500 nm, preferably 100 to 1000 nm, and a sea component composed of an easily soluble polymer having higher solubility in a solution than the above-mentioned island component. The cv% representing the variation of the diameter is 30% or less, preferably 0.01 to 25% or less, more preferably 0.1 to 20% or less, and particularly preferably 1 to 15% or less.

  Even if ultrafine fibers having an island diameter of 50 to 1500 nm are produced using a thermoplastic resin having a surface tension of more than 40 mN / m, it is not preferable because a fiber bundle having excellent water repellency cannot be obtained.

  Examples of the water-repellent thermoplastic resin constituting the island component include polyethylene (PE), polypropylene (PP), polymethylpentene, and fluorine-based thermoplastic resins.

  If the island diameter is less than 50 nm, it is extremely difficult to design a die for arranging a large number of islands, and the operability may be poor. Conversely, if the island diameter exceeds 1500 nm, excellent water repellency cannot be obtained, which is not preferable. When the shape of the island is an irregular cross-section other than the round cross-section, the above-mentioned island diameter is defined as the diameter of a circumscribed circle. Further, if the cv%, which represents the variation in the diameter of the island component, exceeds 30%, it is not preferable because it may cause a yarn break during spinning / drawing.

  The easily soluble polymer as the sea component has a dissolution rate ratio of 200 times or more, preferably 300 times or more, as compared with the poorly soluble polymer as the island component. When the dissolution rate is less than 200 times, while the sea component at the center of the sea-island type composite fiber cross section is dissolved, the island component at the surface layer portion of the separated fiber cross section is dissolved due to a small fiber diameter. Despite the considerable amount being reduced, the sea component in the center of the fiber cross section cannot be completely dissolved and removed, leading to unevenness in the thickness of the island component and solvent erosion of the island component itself, and the uniformity of the object of the present invention. There is a possibility that ultra-fine short fibers having a large fiber diameter cannot be obtained.

  Preferable examples of the easily soluble polymer that forms the sea component include polyesters, aliphatic polyamides, and polystyrene having particularly good fiber-forming properties. More specifically, preferred examples of the easily soluble polymer in the aqueous alkali solution include polylactic acid, an ultrahigh molecular weight polyalkylene oxide condensed polymer, and a copolymerized polyester of a polyalkylene glycol compound and 5-sodium sulfoisophthalic acid. Here, the alkaline aqueous solution refers to an aqueous solution of potassium hydroxide, sodium hydroxide, or the like. Other examples include formic acid for aliphatic polyamides such as nylon 6 and nylon 66, and trichloroethylene for polystyrene, and hot water for polyvinyl alcohol and ethylene-modified vinyl alcohol-based polymers.

  When the island component used in the conjugate fiber is polyolefin, preferred examples of the easily soluble polymer forming the sea component include polyesters, aliphatic polyamides, and polyolefins such as polyethylene and polystyrene, which have particularly good fiber-forming properties. be able to. Among them, polyesters are particularly preferable because of excellent fiber moldability.

  Among the polyester-based polymers, a polyester copolymer containing polyethylene glycol, 5-sodium sulfoisophthalic acid, and diethylene glycol is preferable.

Here, the composition of the sea component will be described below.
The composition of the sea component consists of dicarboxylic acid (A), diol (B), and polyethylene glycol (C or PEG).

  5-sodium sulfoisophthalic acid used as a part of the dicarboxylic acid (A) aims to improve hydrophilicity and melt viscosity, polyethylene glycol (PEG) improves hydrophilicity, and diethylene glycol (DEG) used as the diol (B) ) Contributes to adjustment of the glass transition point and melting point and improvement of hydrophilicity.

  The 5-sodium sulfoisophthalic acid in the polyester copolymer as a sea component is preferably 4 to 16 mol%, more preferably 6 to 14 mol%, based on all dicarboxylic acid components (A) constituting the polyester. Mol%, more preferably 7 to 12 mol%.

  When the amount of 5-sodium sulfoisophthalic acid is less than 4 mol%, sufficient solubility cannot be obtained, and when it exceeds 16 mol%, the number of breaks during spinning of the conjugate fiber increases, and the process stability tends to deteriorate. Is not preferred.

  The amount of polyethylene glycol (PEG) in the polyester copolymer as a sea component is preferably 1 to 10% by weight, more preferably 1 to 8% by weight, and more preferably 100 to 100% by weight of the polyester copolymer (A + B + PEG). Preferably it is 2 to 7% by weight.

When the copolymerization amount of PEG is less than 1% by weight, the dissolution rate of the easily soluble polymer constituting the sea component becomes low, and although the sea component at the center of the fiber cross section is not completely dissolved and removed, Since the island component in the surface layer portion of the already separated fiber cross section is further eroded, not only unevenness in the thickness of the island component is generated, but also strength deterioration is caused, causing problems such as fluff and dyed spots.
On the other hand, if the amount of PEG exceeds 10% by weight, the melt viscosity decreases and the high-speed spinnability deteriorates.

  The molecular weight of PEG is preferably in the range of 2,000 to 14,000, and more preferably in the range of 3,000 to 12,000. If it exceeds 14,000, there is an effect of increasing hydrophilicity, which is considered to be caused by a higher-order structure. However, since reactivity becomes poor and a blend system is formed, problems arise in heat resistance and high-speed spinning stability in spinning. Sometimes.

Next, the amount of diethylene glycol (DEG) in the diol (B) in the polyester copolymer, which is an easily soluble polymer, is preferably from 5 mol% to 80 mol%, more preferably from 7 mol% to 60 mol%. The following are copolymerized. In this case, the intrinsic viscosity of the polyethylene terephthalate-based copolymerized polyester is preferably 0.3 to 0.6.

  When the content of diethylene glycol is less than 5 mol%, the dispersion of the diameter of the island component becomes large when the sea-island composite fiber is formed, and even if the sea component is dissolved and removed, fusion is observed between the polyolefin ultrafine fibers, which is favorable. Dispersibility is not observed, and the wet nonwoven fabric obtained when it is made into a wet nonwoven fabric has undesirably large pores.

  For the polymer forming the sea component, an organic filler, an antioxidant, a heat stabilizer, a flame retardant, a lubricant, a rust inhibitor, a cross-linking agent, as long as it does not affect the spinning properties and the physical properties of the ultrafine fibers after extraction. Various additives such as an agent, a foaming agent, a fluorescent agent, a surface lubricant, a surface gloss improver, and a mold release improver such as a fluororesin may be included.

When producing the sea-island composite fiber using the island component and the sea component, it is preferable that the melt viscosity of the sea component during melt spinning is larger than the melt viscosity of the island component. In such a case, even if the composite weight ratio of the sea component is reduced to less than 40%, the islands are bonded to each other, or most of the island components are bonded to each other, so that the sea-island composite fiber is different. hard.
The preferred melt viscosity ratio (sea / island) is in the range of 1.1 to 6.0, especially 1.3 to 4.0.

  If this ratio is less than 1.1 times, the island components are likely to be joined at the time of melt spinning, while if it exceeds 6.0 times, the viscosity difference is too large and the spinning condition tends to decrease.

  Next, the number of islands is preferably 100 or more, more preferably 300 to 1500. Further, the sea-island composite weight ratio (sea: island) is preferably in the range of 20:80 to 80:20. This range is preferable because the thickness of the sea component between the islands can be reduced, the sea component can be easily dissolved and removed, and the conversion of the island component to ultrafine fibers can be facilitated. Here, when the proportion of the sea component exceeds 80%, the thickness of the sea component becomes too thick, and when it is less than 20%, the amount of the sea component becomes too small, so that bonding is likely to occur between islands.

  As a spinneret used for melt spinning, any one having a group of hollow pins or a group of micropores for forming an island component can be used. For example, a spinneret in which an island component extruded from a hollow pin or a fine hole and a sea component whose flow path is designed to fill the space between them are merged and compressed to form a sea-island cross section may be used. . Examples of the spinneret preferably used are FIGS. 1 and 2 of JP-A-2007-107160, but are not necessarily limited thereto. FIG. 1 shows a method of forming an island by discharging a hollow pin to a sea component resin storage portion and compressing the merged portion. The discharged sea-island composite fibers are solidified by cooling air, and are taken out by a rotating roller or an ejector set at a predetermined take-up speed to obtain an undrawn yarn. The take-up speed is not particularly limited, but is preferably from 200 m / min to 5000 m / min. If it is less than 200 m / min, the productivity is poor. If the speed is 5000 m / min or more, spinning stability is poor.

The obtained undrawn yarn may be subjected to the cutting step or the subsequent extraction step as it is, depending on the use and purpose of the ultrafine fiber obtained after extracting the sea component, or may have the desired strength, elongation and heat. In order to adjust to the shrinkage property, it can be subjected to a cutting step or a subsequent extraction step via a stretching step or a heat treatment step. The drawing process may be a separate drawing method in which spinning and drawing are performed in separate steps, or a straight drawing method in which drawing is performed immediately after spinning in one step.

(Water-repellent ultrafine fiber bundle)
In order to dissolve and remove the sea component of the obtained sea-island type conjugate fiber to obtain a water-repellent ultrafine fiber bundle, any method can be adopted as long as the polymer is selectively eluted. The dissolution and removal of the sea component is preferably performed at the stage of a fabric such as a woven or knitted fabric, but may be performed at the stage of yarn, string, cotton, or a secondary product.

The water-repellent ultrafine fiber bundle obtained above is made of a thermoplastic resin having a surface tension of 40 mN / m or less, preferably 1 to 35 mN / m or less.
The single fiber diameter of the fiber bundle is 50 to 1500 nm, preferably 100 to 1000 nm.
The variation rate CV of the fiber diameter needs to be 30% or less, preferably 0.01 to 25% or less, more preferably 0.1 to 20% or less, and particularly preferably 1 to 15% or less. is there.

  If the surface tension exceeds 40 mN / m and the diameter of the single fiber exceeds 1500 nm, excellent water repellency cannot be obtained without performing post-water repellency processing, which is not preferable. Further, if the single fiber diameter is less than 50 nm and the cv%, which represents the variation in the diameter of the island component, exceeds 30%, it is not preferable because it is a very fine fiber and may cause breakage.

  The contact angle of the water-repellent ultrafine fiber bundle of the present invention is preferably 120 ° or more, more preferably 125 ° or more. If the contact angle is lower than 120 °, satisfactory water repellency cannot be obtained.

  The water-repellent ultrafine fiber bundle of the present invention can be used as an intermediate product such as a woven fabric, a knitted fabric, a felt, a nonwoven fabric, and artificial leather. And these fabrics, intermediate products, and final products made from them have moisture-permeation and waterproof performance. The moisture-permeation and waterproofness refers to a property that does not allow water (water droplets) to pass through but allows moisture (sweat) to pass. Therefore, by using the fiber bundle of the present invention as a raw material, a waterproof effect by excellent water repellency and a moisture permeability by controlling the inter-fiber gap of the ultrafine fiber bundle can be obtained. Waterproofness can be imparted.

  These include clothing such as jackets, skirts, pants, and underwear, sports clothing, clothing materials, interior products such as carpets, sofas, and curtains, vehicle interior products such as car seats, cosmetics, cosmetic masks, wiping cloths, and health products. It can be applied for daily use.

Next, Examples and Comparative Examples of the present invention will be described in detail, but the present invention is not limited thereto. In addition, each measurement item in an Example was measured by the following method.
(1) Surface Tension A film having a thickness of 20 μm was formed from the thermoplastic resin (island component) constituting the water-repellent ultrafine fibers of the present invention, and the measurement was performed in accordance with JIS K6768.
(2) Melt viscosity The sea component and the island component after the drying treatment are set in an orifice set to the melting temperature of the ruder during spinning, melted and held for 5 minutes, and then extruded by applying a load of several levels and shearing at that time. Plot velocity versus melt viscosity. By connecting the plots gently, a shear rate-melt viscosity curve is created, and the melt viscosity at a shear rate of 1000 sec- ¹ is observed.
(3) Island diameter of sea-island composite fiber Using a transmission electron microscope (TEM), a photograph of the fiber cross section perpendicular to the fiber axis direction is taken at a magnification of 30,000 times, and the circumscribed island component of the sea-island composite fiber is taken. The circle was calculated, and the island diameter of the sea-island composite fiber was calculated from the average value (n number = 100).
(4) Measurement of dissolution speed The sea component and the island component were discharged by discharging a capillary having a diameter of 0.3 mm and a length of 0.6 mm from a die having 24 holes, and were drawn at a spinning speed of 1000 to 2000 m / min. The drawn yarn was drawn so that the residual elongation was in the range of 30 to 60% to prepare a multifilament of 83 dtex / 24 filaments. Using this as a bath ratio of 100 with a predetermined solvent and dissolution temperature, the rate of weight loss was calculated from the dissolution time and dissolution amount. In the table, the case where the difference between the sea-island dissolution rates was 200 times or more was judged as pass, and the case where the difference was less than 200 times was judged as failed.
(5) Uniformity of Fiber Diameter of Ultrafine Fiber As the uniformity of the fiber diameter of the ultrafine fiber, the variation (cv%) of the fiber diameter was calculated and evaluated. Take a photograph of the fiber cross section at a magnification of 30,000 times, calculate the circumscribed circle of each single yarn of the ultrafine fiber, find the circumscribed circle diameter, and from the circumscribed circle diameter data of each single yarn of 100 ultrafine fibers selected at random. The average fiber diameter (r2) and standard deviation (σ) were calculated, and the fiber diameter variation coefficient (cv) defined below was calculated.
Fiber diameter variation coefficient (cv%) = σ / r2
(6) Contact Angle Two sea-island composite fibers were plied, and a cylinder knitting (fabric) was performed with a cylinder knitting machine so as to have a stitch of 40 to 55 to produce a length of 30 cm. Thereafter, the tubular knitting is reduced to a water-repellent ultrafine fiber (cloth), air-dried, and 0.1 cc of water is dropped from a distance of 5 mm onto the knitting ground with a dropper. After dropping, the contact angle between the knitted fabric and the water droplet was measured. The measurement result is defined as the contact angle of the water-repellent ultrafine fiber.

[Example 1]
The island component has a surface tension of 34 mN / m, a polypropylene having a melt viscosity at 240 ° C. of 77 Pa · sec, and a sea component has a melt viscosity at 240 ° C. of 300 Pa · sec. Polyester (modified PET1) obtained by copolymerizing 3% by weight of PEG), 9 mol% of 5-sodium sulfoisophthalic acid (SIP), 80 mol% of ethylene glycol (EG), and 20 mol% of diethylene glycol (DEG) was used. : Island = 40:60 Sea-island ratio: 836 islands and 10 filaments were spun using a spinneret and taken off at a spinning speed of 1000 m / min to obtain an undrawn yarn. Subsequently, the undrawn yarn was drawn by a hot roll-hot roll drawing machine at a drawing temperature of 80 ° C and a heat setting temperature of 140 ° C at a draw ratio of 3 to obtain a sea-island type multifilament of 50 dtex.

  The sea-island composite fibers were bundled and immersed in a 4% NaOH aqueous solution at 75 ° C. for 20 minutes to obtain the obtained ultrafine fiber bundle made of polypropylene. At this time, the dissolution rate ratio between the sea component and the island component was 200 times or more. The fiber diameter of the obtained ultrafine polypropylene fiber was 700 nm, and the fiber diameter variation coefficient was 10%.

  In addition, two sea-island composite fibers are plied, and a 30-cm-long tubular knitted fabric is produced by a tubular knitting machine so as to have a stitch length of 40 to 55. After that, it was air-dried to obtain a fabric. The contact angle was 140 °. Other results are shown in Table 1.

[Example 2]
A sea-island type multifilament of 175 dtex was obtained in the same manner as in Example 1. At this time, the dissolution rate ratio between the sea component and the island component was 200 times or more. Subsequently, weight reduction was performed in the same manner as in Example 1, and the fiber diameter of the obtained ultrafine polypropylene fiber was 1300 nm, and the fiber diameter variation coefficient was 9%. The contact angle measured by the same measurement method as in Example 1 was 125 °. Other results are shown in Table 1.

[Example 3]
A 17 dtex sea-island type multi-layered multi-layer of the same method as in Example 1 except that high-density polyethylene (HE495 manufactured by Mitsubishi Chemical Corporation) having a surface tension of 32 mN / m and a melt viscosity at 240 ° C. of 130 Pa · sec was used as the island component. Filament was obtained. At this time, the dissolution rate ratio between the sea component and the island component was 200 times or more. Subsequently, weight reduction was carried out in the same manner as in Example 1, and the obtained ultrafine polypropylene fiber had a fiber diameter of 400 nm and a fiber diameter variation coefficient of 15%. The contact angle measured by the same measuring method as in Example 1 was 150 °. Other results are shown in Table 1.

[Comparative Example 1]
A sea-island type multifilament of 300 dtex was obtained in the same manner as in Example 1. At this time, the dissolution rate ratio between the sea component and the island component was 200 times or more. Subsequently, weight reduction was performed in the same manner as in Example 1, and the fiber diameter of the obtained ultrafine polypropylene fiber was 1700 nm, and the fiber diameter variation coefficient was 12%. The contact angle measured by the same measuring method as in Example 1 was 110 °. Other results are shown in Table 1.

[Comparative Example 2]
An attempt was made to obtain a 0.3 dtex sea-island type multifilament so that the diameter of the ultrafine fiber became 40 nm in the same manner as in Example 1, but it was difficult to collect a sample due to thread breakage. Other results are shown in Table 1.

[Comparative Example 3]
Polyethylene terephthalate having a surface tension of 43 mN / m and a melt viscosity at 290 ° C. of 100 Pa · sec was used as the island component. Melt viscosity at 280 ° C. is 300 Pa · sec as a sea component, 3% by weight of polyethylene glycol (PEG) having a molecular weight of 4000, 9 mol% of 5-sodium sulfoisophthalic acid (SIP), and ethylene glycol (EG) as a diol component. Using 100 mol% copolymerized polyester (modified PET2), spinning is performed with a sea: island = 30: 70 sea / island ratio using a die of 836 islands and 10 filaments, taken up at a spinning speed of 1000 m / min, and an undrawn yarn is obtained. Obtained. A sea-island type multifilament of 62 dtex was obtained in the same manner as in Example 1 except that the sea component was used. At this time, the dissolution rate ratio between the sea component and the island component was 200 times or more. Subsequently, weight reduction was performed in the same manner as in Example 1, and the resulting polyethylene terephthalate ultrafine fibers had a fiber diameter of 700 nm and a fiber diameter variation coefficient of 11%. The contact angle measured by the same method as in Example 1 was 60 °. Other results are shown in Table 1.

[Comparative Example 4]
As the island component, nylon 6, 6 having a surface tension of 46 mN / m and a melt viscosity of 100 Pa · sec was used. In the same manner as in Comparative Example 3, a sea-island type multifilament of 50 dtex was obtained. At this time, the dissolution rate ratio between the sea component and the island component was 200 times or more. Subsequently, weight reduction was performed in the same manner as in Example 1, and the resulting polyethylene terephthalate ultrafine fibers had a fiber diameter of 700 nm and a fiber diameter variation coefficient of 10%. When the contact angle was measured in the same manner as in Example 1, the contact angle could not be measured because water droplets were immediately absorbed by the fibers. Other results are shown in Table 1.

  The water-repellent ultrafine fiber bundle made of the water-repellent thermoplastic ultrafine fiber of the present invention exhibits excellent water repellency without performing post-water-repellent processing, and can be woven, knitted, and variously processed from wet nonwoven fabrics. It can be combined with fiber products to give excellent water repellency.

1: Island component polymer reservoir portion before distribution 2: Inlet hole for island component distribution 3: Sea component introduction hole 4: Sea component polymer reservoir portion before distribution 5: Individual sea / island = sheath / core structure forming portion 6: Constriction of the entire sea-island Part 7: Distance from outermost row of island component distribution introduction holes to outer periphery

Claims (3)

  The surface tension is made of a thermoplastic resin having a surface tension of 40 mN / m or less, and the fiber made of the thermoplastic resin has a single fiber diameter of 50 to 1500 nm, and a variation rate CV of the fiber diameter is 30% or less. Water-repellent ultrafine fiber bundle.   The water-repellent microfine fiber bundle according to claim 1, comprising a water-repellent microfine fiber having a contact angle of 120 ° or more.   A cloth comprising the water-repellent ultrafine fiber bundle according to claim 1 or 2.

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