KR102502868B1 - Heat-sealed core-sheath type composite fiber and tricot letter - Google Patents

Abstract

There is little fluff generation in high-order processes, high-order passability is excellent even in applications requiring high quality and quality, such as tricot applications, and the woven fabric after thermal bonding has excellent strength, dimensional stability, and durability, and the channel material of liquid filtration membranes The following fibers are provided as heat-sealable core-sheath composite fibers with excellent quality as a fiber. A core-sheath type conjugate fiber made of polyester with a melting point of 250°C or higher as the core and a polyester sheath with a melting point of 215°C or higher and a melting point lower than that of the polyester constituting the core by 20 to 35°C, and having a strength of 3.8 cN/dtex or higher. , Heat-bonded core-sheath type composite fiber, characterized in that the elongation is 35% or more.

Description

Heat-sealed core-sheath type composite fiber and tricot letter

The present invention has little fluff generation in high-order processes, excellent high-order passability even in applications requiring high quality and quality, such as tricot applications, and a woven fabric after thermal bonding has excellent strength, dimensional stability, and durability, and a liquid filtration membrane It relates to a heat-sealable core-sheath type composite fiber with excellent quality as a channel material for

Polyester fiber is suitable as a raw material fiber for clothing, industrial materials, etc., due to its excellent dimensional stability, weather resistance, mechanical properties, durability, and productivity that can be mass-produced at a relatively low cost, and is used in various fields and uses.

In recent years, for material applications such as water treatment membranes and filters, interior applications such as chair covers and partitions, and various other medical applications, polyester fibers are woven and knitted, and then subjected to heat treatment such as calendering to produce fibers. The use of heat-sealable polyester fibers, which can improve the shape retention and rigidity of fabrics by partially melting them and thermally bonding the fibers together, is progressing. Among them, the demand for water treatment membranes is increasing year by year in order to solve the serious water shortage caused by population growth in the Middle East and Africa. Demand for polyester tricot euro materials in which tricot letters are thermally bonded is rapidly increasing.

As the polyester fiber having thermal adhesiveness, yarns composed of two or more kinds of polyesters having different melting points or softening points are suitable. As its form, for example, mixed filament yarn composed of filament yarn, core-sheath type or side-by-side type conjugate fiber is exemplified. Compared to mixed filament yarns in which filaments with different melting points are mixed at the single yarn level, composite fibers composed of polymers with different melting points are superior in quality after thermal bonding. In particular, it is a core-sheath composite yarn with excellent quality such as productivity of yarn and surface smoothness of fabric after heat treatment, and a heat-sealable core-sheath type composite fiber in which the sheath component is composed of a component with a lower melting point or softening point than the core component is actively used.

As the heat-sealable core-sheath-type composite fiber, a core-sheath-type composite fiber (Patent Document 1) having a polyester core in which the main repeating unit is composed of ethylene terephthalate and a polymer having a softening temperature of 130 to 200 ° C. as a sheath is proposed there is.

According to the core-sheath type conjugate fiber, it is possible to obtain a heat-bonded woven fabric having a predetermined strength and elongation, without generating wrinkles or creases due to misalignment at the heat-bonded junction, and having a good quality. However, as a preferred composition of the polymer used for the sheath component is polyester copolymerized with isophthalic acid, the polymer of the sheath portion has low crystallinity and does not have a clear melting point. For this reason, when the woven or knitted fabric made of the core-sheath type conjugate fibers is thermally bonded, unevenness in the adhesion between the conjugate fibers occurs, resulting in dimensional stability and variations in fabric strength, resulting in poor quality when used as a channel material for liquid filtration membranes. There was a problem with falling.

On the other hand, a core-sheath type in which a core is a polymer in which 90 mol% or more of the repeating units are composed of ethylene terephthalate, and a copolymer polybutylene terephthalate in which 60 to 90 mol% of the repeating units is composed of butylene terephthalate is used as a sheath. Composite fibers (Patent Document 2) have been proposed.

According to the core-sheath type composite fiber, since the sheath component is endowed with appropriate crystallinity and the fiber properties such as boiling water shrinkage rate and heat shrinkage stress peak temperature are good, it is possible to obtain a thermally bonded woven or knitted product of good quality. .

In addition, tricot knitted fabric using the heat-sealable core-sheath type composite fiber described in Patent Document 3 or Patent Document 4 has also been reported. In these techniques, polyester with a very low melting point of the sheath component is used for the high melting point polyester of the core component, and if the spinning temperature is set only at the melting point of the polyester core component, thermal degradation of the sheath component tends to proceed. On the other hand, if the spinning temperature is lowered in consideration of the melting point of supercomponent polyester, the strength of the core component cannot be maximized, so the conjugate fiber has poor strength.

Japanese Unexamined Patent Publication No. 62-184119 Japanese Unexamined Patent Publication No. 2000-119918 Japanese Unexamined Patent Publication No. 2011-245454 Japanese Unexamined Patent Publication No. 2014-070279

Since the core-sheath type composite fiber described in Patent Document 2 lacks strength and elongation, it is processed at high tensile strength and high speed, and it is difficult to deploy to tricot applications where yarn quality defects such as fluff are markedly expressed as fabric defects. There was a problem that it was difficult. In addition, since the melting point of the sheath component is low, it is not possible to increase the thermal bonding temperature after weaving, so the shrinkage of the composite fibers constituting the fabric is insufficient, resulting in water treatment membrane channel materials that require high dimensional accuracy in the design of the fabric. In terms of applications, there was a problem with dimensional stability when used under high pressure for a long period of time. In addition, since the heat-sealable core-sheath type composite fiber described in Patent Document 3 or Patent Document 4 has low elongation, high order passability is low, and the elongation when fabricated is insufficient, resulting in durability when used as a channel material for a long period of time. There was a problem with this falling off. In addition, for the same reason as in Patent Document 2, since the thermal bonding temperature after weaving cannot be increased, the shrinkage of the fibers constituting the fabric is insufficient, so it is suitable for applications such as water treatment membrane channel materials requiring high dimensional accuracy in fabric design. However, dimensional stability when used under high pressure for a long period of time had a problem as a matter of fact.

The present invention solves the problems of the prior art, generates little fluff in high-order processes, has excellent high-order passability even in applications requiring high quality and quality such as tricot applications, and provides strength and dimensional stability to woven fabrics after thermal bonding. To provide a heat-sealable core-sheath type composite fiber with excellent durability and excellent quality as a channel material for a liquid filtration membrane.

In order to solve the above problems, the present invention consists of the following configuration.

(1) A core-sheath type conjugated fiber in which a polyester having a melting point of 250°C or higher is used as a sheath for a core having a melting point of 215°C or higher and a melting point lower than that of the polyester constituting the core by 20 to 35°C as a sheath, and has a strength of 3.8 cN/dtex. Above, heat-sealable core-sheath type composite fiber characterized in that the elongation is 35% or more.

(2) In (1),

A heat-sealable core-sheath-type composite fiber in which the total fineness of the core-sheath composite fiber is 30 dtex or more and the single yarn fineness is 3.0 dtex or less.

(3) A tricot knitted fabric comprising the heat-sealable core-sheath type composite fiber according to (1) or (2).

(Effects of the Invention)

According to the present invention, there is little fluff generation in high-order processes, high-order passability is excellent even in applications requiring high quality and quality, such as tricot applications, and woven fabrics after thermal bonding have excellent strength, dimensional stability, and durability, It is possible to provide a heat-sealable core-sheath type composite fiber with excellent quality as a channel material for a liquid filtration membrane.

1 shows an example of the cross-sectional shape of a single yarn of a heat-sealable core-sheath type conjugate fiber preferably used in the present invention.
2 is an example of the cross-sectional shape of a single yarn of the heat-sealable core-sheath type composite fiber of the present invention, and is a view for explaining the cross-sectional eccentricity.

Hereinafter, the heat-sealable core-sheath type composite fiber of the present invention will be described in detail.

The core-sheath type conjugate fiber of the present invention is composed of polyester having a core component melting point of 250 ° C. or higher, and polyester having a sheath component melting point of 215 ° C. or higher and 20 to 35 ° C. lower than the melting point of the polyester constituting the core part.

By setting the melting point of the core component polyester to 250 ° C. or higher, the spinning temperature can be increased to the extent that the polyester's strength characteristics can be maximized, and the strength and durability when made into a fabric are excellent. It is preferable that the melting|fusing point of core component polyester is 270 degreeC or less from the practical upper limit. When the core component polyester has a melting point of 270° C. or less, it is not necessary to perform extremely high-temperature spinning, and spinning can be performed using a general-purpose melt spinning machine, which is preferable. More preferably, it is 253 degreeC or more and 260 degreeC or less.

The melting point of supercomponent polyester is 215°C or higher and preferably 250°C or lower. If the melting point of the supercomponent polyester is 250 ° C. or less, it is preferable because it is possible to use a general-purpose device for thermal bonding of the fabric and suppress fumes due to the oil component in the thermal bonding process. More preferably, it is 220 degreeC or more and 235 degreeC or less. By setting the difference in melting point between the super component polyester and the core component polyester to 20°C or more, the thermal bonding temperature of the fabric can be set to a temperature sufficiently lower than the melting point of the core component polyester, making it a highly durable fabric that takes advantage of the strength of the yarn. can do. In addition, by setting the melting point difference to 35 ° C. or less, the spinning temperature can be set to a temperature that maximizes the elongation of the core component polyester and suppresses thermal degradation of the super component polyester as much as possible. It is a composite fiber with less fluff and excellent quality. The melting point difference between super component polyester and core component polyester is preferably 23°C or more and 30°C or less.

Further, the softening temperature of the core component polyester is preferably 245°C or higher, and the softening temperature of the super component polyester is preferably 205°C or higher. When the softening temperature of the core component polyester is 245 ° C. or higher, the dimensional change is small when the fabric is thermally bonded at a temperature higher than the melting point of the super component polyester, and the shape of the fabric is stabilized, which is preferable. The softening temperature of the core component polyester is more preferably 250°C or higher. The upper limit temperature of the softening temperature of core component polyester is 270 degreeC in practical use.

When the softening temperature of the supercomponent polyester is 205° C. or higher, it is preferable because there is no fusion to the heater during heat setting in the processing step and the high-speed passability is stable. The softening temperature of supercomponent polyester is more preferably 215°C or higher. By setting the melting point of the sheath component polyester to 215°C or higher and the softening point to 205°C or higher, the thermal bonding temperature after forming into a fabric can be sufficiently high. It is preferable because the dimensional stability of is improved. The upper limit of the softening temperature of supercomponent polyester is 250°C in practice.

As the core component polyester, any polyester can be selected as long as the melting point is within the above range, but polyethylene terephthalate (hereinafter referred to as PET) is preferable from the viewpoint of dimensional stability and strength characteristics. PET is a polyester obtained by using terephthalic acid as a main acid component and ethylene glycol as a main glycol component. As long as the melting point is within the above range, core component polyester may contain a copolymerization component as appropriate. Examples of copolymerizable compounds include dicarboxylic acids such as isophthalic acid, succinic acid, cyclohexanedicarboxylic acid, adipic acid, dimer acid, sebacic acid, and 5-sodium sulfoisophthalic acid, ethylene glycol, for PET. Diols such as diethylene glycol, 2,2-dimethyl-1,3-propanediol, butanediol, neopentyl glycol, cyclohexanedimethanol, polyethylene glycol, polypropylene glycol, and bisphenol A ethylene oxide adducts are exemplified. However, it is more preferable that 100% of the homo PET is composed of repeating units of ethylene terephthalate in terms of dimensional stability and strength characteristics. Moreover, you may add inorganic fine particles, such as titanium dioxide, as a matting agent, and silica fine particles as a lubricant as needed.

As the supercomponent polyester, any polyester can be selected as long as the melting point is within the above range, but besides PET, polytrimethylene terephthalate and polybutylene terephthalate are preferable. When PET is used as the core component polyester, it is particularly preferable to use PET as the super component polyester in view of suppression of peeling at the composite interface. Any copolymerization component can be added in an arbitrary ratio as long as the melting point is within the above range, but if copolymerized PET comprising 70 mol% or more of repeating units of ethylene terephthalate, the polymer has appropriate crystallinity. It can be given, and since spinning workability is stable, it is preferable. In addition, when the fabric is thermally bonded, thermal bonding non-uniformity is unlikely to occur, which is preferable. It is more preferable if it is copolymerized PET which consists of 80 mol% or more repeating units of ethylene terephthalate. Even when a polymer other than PET is used as the supercomponent polyester, a copolymerization component can be appropriately added within a range that does not impair yarn productivity or the quality of the fabric after thermal bonding. As a copolymerization component, arbitrary components, such as the above-mentioned copolymerization component, can be copolymerized. In addition, regardless of the selected polymer species, inorganic fine particles such as titanium dioxide as a matting agent and silica fine particles as a lubricant may be added as necessary.

Next, it is preferable that the intrinsic viscosity (hereinafter referred to as IV) of the composite fiber is 0.55 to 0.75. When the IV is 0.55 or more, the degree of polymerization is not too low, and sufficient toughness can be achieved so that the composite fiber can withstand practical use, so it is preferable. On the other hand, when the IV is 0.75 or less, the IV is not too high during spinning, there is no need to perform extremely high-temperature spinning, the increase in the amount of COOH during melt spinning can be suppressed, melt fracture does not occur, and uniform This is preferable because a single conjugate fiber is obtained and the toughness is not reduced. More preferably, IV is in the range of 0.60 to 0.70.

1 is a cross-sectional schematic diagram of a core-sheath-type conjugate fiber of the present invention, and is a core-sheath-type conjugate fiber 10 in which a sheath component 2 surrounds a core component 1.

The cross-sectional shape of the composite fiber is not particularly limited as long as the high melting point component is placed as the core and the low melting point component is arranged in a sheath covering the core, but it is preferable that the sheath component completely covers the core component and does not expose the core component. In addition, for the stability of physical properties such as yarn productivity and Worcester non-uniformity (U%), the eccentricity of the center of the core component with respect to the center of the entire composite fiber in the cross section of the composite fiber is preferably 5% or less. If the eccentricity is 5% or less, even if the combination of the core component and the sheath component polymer produces a difference in shrinkage, coil-shaped crimping does not occur, and the fabric quality is excellent, so it is preferable. More preferably, the eccentricity is 1% or less.

Further, the cross-sectional outer circumferential shape of the conjugate fiber is preferably substantially circular with an flattening ratio of 1.1 or less expressed by A/B when A is the major axis and B is the minor axis of the columnar shape. By adopting such a shape, the force can be uniformly distributed and received when external tension is received, and the variation in strength and elongation in the S-S curve of the composite fiber is also reduced, which is preferable. More preferably, the flattening ratio is 1.0.

The composite ratio of core component and sheath component in the core-sheath type composite fiber is preferably that the cross-sectional area ratio of core:sheath is 40:60 to 90:10, more preferably 55:45 to 75:25. When the composite ratio is within the above range, the composite fibers can be stably spun, have excellent stretchability, little fuzzing, and are preferable because the stretchability can be maintained even when the fabric is thermally bonded.

The content of the inorganic particles contained in the core component is preferably 3.0% by weight or less, since toughness is improved, and more preferably 0.5% by weight or less. When the content rate of the inorganic fine particles included in the vinegar component is 0.05% by weight or more, process passability is improved, so it is preferable. More preferably, the content of inorganic fine particles included in the vinegar component is 0.05% by weight or more and 0.5% by weight or less, so that the guide is not excessively worn during the process, and when used as a channel member, unnecessary inorganic particles are not dropped off. do. As for the inorganic fine particles, titanium oxide is preferable from the point of view of passing the process as a composite fiber.

In the composite fiber of the present invention, the total fineness is preferably 30 dtex or more. By setting the total fineness to 30 dtex or more, sufficient strength and rigidity can be secured even after thermal bonding treatment, and when used as a channel material, a sufficient amount of permeate can be ensured even when water pressure acts. The total fineness is preferably 90 dtex or less, more preferably 40 dtex or more. By setting the total fineness to 90 dtex or less, thinning of the fabric is achieved, and when used as a channel material, it is preferable to increase the number of laminates per unit formed by joining the filtration membrane and the channel material.

In addition, the single yarn fineness of the composite fiber is preferably 3.0 dtex or less. By setting the single yarn fineness to 3.0 dtex or less, the specific surface area is large, thermal bonding can be performed uniformly even in a short time heat bonding process, and the decrease in strength of the fabric due to the thermal bonding process can be suppressed, so that a highly durable fabric can be obtained. there is. The single yarn fineness is preferably 0.7 dtex or more, more preferably 1.5 dtex or more and 2.5 dtex or less. By setting the single yarn fineness to 0.7 dtex or more, yarn unevenness and yarn fluffing are reduced, stably spinning is possible, and knitting yarn breakage is reduced, high order passability is excellent, and appropriate stiffness is obtained even when made into a fabric. This is preferable because it is possible.

The strength of the composite fiber is 3.8 cN/dtex or more, and the elongation is 35% or more. By setting the strength to 3.8 cN/dtex or more, the strength when used as a fabric is high, and the durability when used as a channel material is excellent. The practical upper limit is a strength of 7.0 cN/dtex. In addition, by setting the elongation to 35% or more, fluffing of the yarn can be prevented, and a fabric with excellent high-order passability and excellent quality with fewer defects can be produced with less yarn breakage during weaving and less yarn breakage during weaving. do. It is more preferable that the elongation is 35 to 50%. A woven or knitted fabric obtained by setting the elongation to 50% or less is preferable because of its excellent dimensional stability.

Worcester nonuniformity (U%), which is an index of thickness nonuniformity in the fiber length direction of composite fibers, is preferably set to 1.4% or less in order to obtain a highly uniform fabric. If the Worcester non-uniformity (U%) is 1.4% or less, the surface of the fabric after thermal bonding becomes smooth, and when used as a channel material, a uniform channel can be formed, which is preferable. More preferably, it is 1.0% or less of Worcester nonuniformity (U%).

It is preferable that the dry heat shrinkage of the composite fiber is 20% or less. When the dry heat shrinkage rate is 20% or less, it is preferable because the dimensional change due to the thermal bonding treatment can be suppressed. The practical lower limit is 2.0% of dry heat shrinkage.

A preferable method for making yarn for achieving the object of the present invention will be described.

As the spinneret used in the melt spinning method of the heat-sealable core-sheath composite fiber of the present invention, a conventional spinneret for composite spinning may be used.

As the melting method, a method using a pressure melter and a method using an extruder are exemplified, but melting using an extruder is preferable from the viewpoint of efficiency and suppression of decomposition. The melting temperature is preferably set to a temperature higher than the melting point of the polymer used by 10 to 40°C.

A preferred spinning temperature is 280 to 295°C. More preferably, the spinning temperature is 285°C to 293°C. By employing such a spinning temperature, a composite fiber having high toughness and good yarn-making properties can be obtained. A heating heater may be installed under the cap to mitigate rapid cooling directly under the cap.

It is preferable to shorten the melting passage time from melting to discharge and the heating time as much as possible because the molecular weight of each of the core component and the sheath component can be suppressed. Core components and sheath components are individually melt-kneaded, discharged and weighed precisely through a heating zone, passed through a filtration layer for foreign matter replenishment, and discharged, threaded, and cooled using a composite spinneret to form a core-sheath shape. If the residence time of the polymer, which is the passage time from melting to ejection, is within 30 minutes, the thermal degradation of the polymer can be reduced, and the decrease in IV can be suppressed, thereby preventing the decrease in yarn toughness. In addition, since an increase in the amount of COOH in the composite fiber can be suppressed, fluffing is suppressed, heat resistance is excellent, high-order passability is excellent, and durability when made into a fabric can be improved, so it is preferable. More preferably, it is 20 minutes or less of polymer residence time.

From the balance of strength and productivity, it is preferable to set the nozzle surface temperature to 270 ° C. or more and 290 ° C. or less. By setting the nozzle surface temperature to 270 ° C. or higher, the characteristics of the core component can be maximized, and yarns with excellent strength and elongation can be obtained. Setting the spinneret surface temperature to 290° C. or lower is preferable because the increase in yarn breakage due to the deposition of the polymer hydrolyzate immediately below the spinneret is suppressed and the yarn productivity is excellent.

The core-sheath type conjugate fiber of the present invention is a two-step method in which the discharged polymer is used as an unstretched yarn, once taken up, and then drawn, as well as a one-step method such as a direct spinning and drawing method in which spinning and drawing steps are continuously performed, a high-speed weaving method, or any other method. It can also be manufactured in a process.

As the drawing temperature, it is preferable to carry out at 60 ° C. or more and 100 ° C. or less, which is around the glass transition temperature of the unstretched yarn. By setting the drawing temperature to 60° C. or higher, uniform drawing can be performed, and by setting the drawing temperature to 100° C. or lower, deterioration in productivity due to fusion to a drawing roll or spontaneous stretching of fibers can be prevented. More preferably, the stretching temperature is 75°C or higher and 95°C or lower.

In addition, after drawing, it is preferable to heat set at a temperature at which the crystallization speed of the undrawn yarn is maximized, and it is preferable to set it to 110°C or more and 180°C or less. Heat setting at 110 ° C. or higher is preferable because it promotes crystallization of the fiber and increases strength, as well as stabilization of various physical properties including shrinkage stress and dry heat shrinkage. In addition, heat setting at 180° C. or less is preferable because deterioration in productivity due to fusion of conjugate fibers to a heat setting device can be prevented.

Example

Hereinafter, examples will be described in detail. In addition, the main measurement value of an Example was measured by the following method.

(1) Intrinsic viscosity (IV)

ηr in the definition formula is obtained by dissolving 0.8 g of a sample in 10 mL of O-chlorophenol (OCP) with a purity of 98% or more, using an OSTWALD viscometer at a temperature of 25 ° C. Calculated.

ηr=η/η0=(t×d)/(t0×d0)

Intrinsic Viscosity (IV)=0.0242ηr+0.2634

[η: viscosity of polymer solution, η0: viscosity of OCP, t: drop time of solution (sec), d: density of solution (g/cm), t0: drop time of OCP (sec), d0: density of OCP (g/cm 3 )].

(2) melting point

Using a differential scanning calorimetry (DSC) Q100 manufactured by TA Instruments, 10 mg of the dried sample was weighed, sealed in an aluminum pan, and measured from room temperature to 300°C at a heating rate of 16°C/min in a nitrogen atmosphere. After the first measurement (1st run), the mixture was held for 5 minutes, then rapidly cooled to room temperature, followed by a second measurement (2nd run), and the peak top temperature of the melting peak in the 2nd run was taken as the melting point.

(3) softening temperature

Using a thermal mechanical device (TMA/SS-6000) manufactured by Seiko Instruments Inc., a dry sample is placed on a sample stage, and a measurement load of 10 g is applied using an immersion probe with a tip diameter of 1.0 mm from room temperature to 300 ° C. in a nitrogen atmosphere. The temperature increase rate was measured at 16°C/min. The temperature at the start of displacement was defined as the softening temperature.

(4) Section eccentricity

The cross section of the fiber was observed using a microscope VHX-2000 manufactured by Keyence Corporation, and each value was measured using the attached image analysis software, the center position of the core component was C1 (3 in Fig. 2), and the center position of the composite fiber was determined. When Cf (4 in Fig. 2) and the radius of the composite fiber were rf (5 in Fig. 2), the cross-sectional eccentricity was calculated from the following equation.

Section eccentricity (%)={|Cf-C1|/rf}×100.

(5) section flatness

The composite fiber cross section was observed by the same method as in (4), and the longest diameter (A) and the shortest diameter (B) were defined as the longest diameter among the diameters passing through the center of the cross section, and the cross-sectional flatness was calculated according to the following formula .

Section flatness=major axis (A)/minor axis (B).

(6) Fineness, strength, elongation, toughness

It was measured according to JIS L1013 (2010, chemical fiber filament yarn test method). Toughness was calculated with the following formula.

(Toughness) = (Strength) × (Elongation) ^0.5 .

(7) Worcester nonuniformity (U%)

Using a USTER TESTER 4-CX manufactured by Zellweger, the measurement was performed in normal mode while feeding the yarn at a speed of 200 m/min for 5 minutes.

(8) Boiling water shrinkage rate, dry heat shrinkage rate

Cassettes for 10 times were produced using a frame circumference of 1.0 m using a detector, and calculated according to the following formula. In addition, when measuring both the original length and the length after treatment, a load {(display fineness (dtex) × 2) g} was applied and measured. Regarding the shrinkage treatment, the boiling water shrinkage rate was immersed in boiling water for 15 minutes, and the dry heat shrinkage rate was treated at 200 ° C. for 5 minutes.

Shrinkage rate (%) = {(raw length (L1) - length after treatment (L2)) / original length (L1)} × 100.

(9) Number of fluff defects

Using a ply counter (MFC-120S) manufactured by Toray Engineering Co., Ltd., 48 composite fibers were measured under the measurement conditions of yarn unwinding speed = 500 m/min and measurement length = 50000 m, and the number of detected fluffs was counted. Based on the counted number of fluffs, it was set as the following score.

3 points: 0 for a total of 48

2 points: The average number of 48 items is less than 0.1, and the maximum number of 48 items is 1

1 point: The average number of 48 items is 0.1 or more and less than 0.3, and the maximum number of 48 items is 1

0 points: The average number of 48 items is 0.3 or more, or the maximum number of 48 items is 2 or more.

(10) High order permeability

When the composite fiber of the present invention is knitted with a double denby seam using a tricot knitting machine (36 gauge) composed of two bodies using the yarns obtained by the present invention for both the front yarn and the back yarn after warping, The following evaluation scores were given for the number of warp fluff detecting fingers and the number of knitting yarn breaks.

3 points: less than 0.3 lint/10 million m of warp yarn, and less than 0.5 times/200 m of yarn breakage

2 points: 0.3 yarn/10 million m or more and less than 0.6 yarn/10 million m, and yarn breakage 0.5 times/200 m or less, or warp yarn 0.3 yarn/10 million m or less, and yarn break 0.5 times/200 m or more 1.0 times/less than 200m

1 point: 0.3 yarn/10 million m or more and 0.6 yarn/less than 10 million m, and yarn breakage 0.5 times/200 m or more and 1.0 times/200 m or more

0 point: 0.6 warp yarn/10 million m or more, or 1.0 yarn break/200 m or more.

(11) Fabric strength after thermal bonding

A tricot knitted fabric was produced by the method of (10), and heat treatment was performed by the melting point of the sheath component + 10 ° C in a pin tenter dryer under no load, and a thermally bonded fabric was produced. The density of the fabric after thermal bonding was adjusted to be 66/2.54 cm (= inch) in the wale direction and 53/2.54 cm (= inch) in the course direction. The strength of the fabric after thermal bonding was measured in accordance with JIS 1096: 2010 (Dough test method for woven and knitted fabrics) in each of the wale (vertical) and course (transverse) directions, and based on the strength value, the following score was given.

3 points: 600 N/5 cm or more in length and 100 N/5 cm or more in width

2 points: 500 N/5 cm or more and less than 600 N/5 cm, and 100 N/5 cm or more, or 600 N/5 cm or more, and 80 N/5 cm or more and less than 100 N/5 cm

1 point: Vertical 500 N/5 cm or more and less than 600 N/5 cm, and horizontal 80 N/5 cm or more and less than 100 N/5 cm

0 point: Less than 500 N/5 cm in length or less than 80 N/5 cm in width.

(12) Water resistance test of channel material (salt removal rate (%), tidal volume (㎥/day))

The thermally bonded tricot knitted fabric fabricated in the same way as in (11) was sandwiched between two RO separators with a thickness of 150 μm to form a spiral unit, mounted on a module with a diameter of 0.2 m and a length of 1 m, and TDS (soluble evaporation residual water) was filtered for 5 days with a differential pressure of 4.5 MPa at a liquid temperature of 25 ° C. After 5 days, the electrical conductivity of the permeate was measured, and the magnesium sulfate removal rate was calculated. In addition, the amount of permeated liquid after 5 days was measured, and the amount of fresh water per day was calculated. Based on the results of the test, it was set as the following evaluation scores.

3 points: The removal rate of magnesium sulfate is 99.8% or more, and the amount of tidal water is 45 m3/day or more

2 points: The magnesium sulfate removal rate is 99.8% or more, and the tidal volume is 40 m3/day or more and less than 45 m3/day, or the magnesium sulfate removal rate is 99.0% or more and less than 99.8%, and the tidal volume is 45 m3/day more

1 point: The removal rate of magnesium sulfate is 99.0% or more and less than 99.8%, and the tidal volume is 40 m3/day or more and less than 45 m3/day

0 points: The removal rate of magnesium sulfate is less than 99.0%, or the amount of tidal water is less than 40 m3/day.

(13) Pass or fail judgment

In the evaluation items (9) to (12), the case where all scores were 2 points or more was regarded as pass, and the case where even one score was 1 point or less was regarded as disqualified.

Example 1

7.1 mol% and 4.4 mol of isophthalic acid and bisphenol A ethylene oxide adduct, respectively, as copolymerization components, with IV0.67 homo PET polymer (high melting point component, melting point 255 ° C.) that does not contain titanium oxide, based on the total acid component A copolymerized PET polymer (low melting point component, melting point 230°C) having a % copolymerized titanium oxide content of 0.05wt% and IV0.65 was prepared, the high melting point component was melted at 285°C by an extruder, and the low melting point component Melting at 260 ° C. with an extruder, setting the spinning temperature at 290 ° C., measuring with a metering pump, filtering in a pack, and concentric core and sheath cross-sectional shape (cross-sectional eccentricity) as shown in FIG. It was discharged as a core-sheath composite type with a composite area ratio of 65:35 so that the cross-sectional flatness was 0% and the cross-sectional flatness was 1.0). At this time, the high-melting-point component was arranged as the core and the low-melting-point component as the sheath.

As the drawing device, the direct spinning method (DSD), which performs drawing and winding all at once, is adopted, and the ejected polymer passes through a cooling section and an oil supply section, and a drawing roll (1st HR) set at a speed of 1728 m/min and a surface temperature of 85 ° C. , and without winding once, it was continuously wound with a heat treatment roll (2nd HR) set at 4489 m/min and 128° C., and stretched 2.6 times. The stretched and heat-treated yarns are tensioned by godet rollers (3rd GR, 4th GR) set at speeds of 4549 m/min and 4584 m/min, respectively, and cheese by a tension of 0.20 cN/dtex at a speed of 4500 m/min. The shaped package was wound up to obtain a core-sheath type composite fiber of 56 dtex-24 filaments. Table 1 shows the evaluation results for the obtained fibers. The Worcester unevenness (U%) was 0.4%, the boiling water shrinkage was 10.3%, and the dry heat shrinkage was 17.2%.

As shown in Table 1, the strength and toughness were excellent, and the occurrence of fluff of the yarn was small, which was good. The obtained yarn was used for both the front yarn and the back yarn, and was knitted with a seam of double denby structure using a tricot knitting machine (36 gauge) composed of two bodies. Excellent. In addition, the strength of the fabric after thermal bonding with a pin tender at 240 ° C (melting point of vinegar + 10 ° C) is high, and as a result of using it as a channel material for a water treatment membrane, the tricot channel material has excellent dimensional stability due to high-temperature heat treatment , It was possible to secure a stable amount of fresh water while maintaining membrane performance without damage or clogging of the passage material during continuous use.

Examples 2-4, Comparative Examples 1-3

In Examples 2 to 4 and Comparative Examples 1 to 3, the melting point of the core component polyester and the sheath component polyester was changed using the copolymerization component used in the sheath component of Example 1, respectively, and the melting point as shown in Table 1. , and accordingly, the same as in Example 1 was followed except that an appropriate spinning temperature was adopted. The evaluation results are shown in Table 1.

Example 5

Example 5 was in accordance with Example 1 except that the spinning machine was changed from DSD to two process methods and the spinning conditions were incidentally adjusted. The evaluation results are shown in Table 1.

Examples 6-7

Examples 6 to 7 were in accordance with Example 1 except that the shape of the discharge port of the spinneret was changed and the cross-sectional shape and eccentricity of the core sheath were changed as shown in Table 2. The evaluation results are shown in Table 2.

Examples 8-11

Examples 8 to 11 were in accordance with Example 1 except that the fineness and the number of filaments of the composite fiber were changed as shown in Table 2. The evaluation results are shown in Table 2.

Examples 12-14

Examples 12 to 14 were in accordance with Example 1 except for changing the amount of titanium oxide added to the core component polyester and super component polyester as shown in Table 3. The evaluation results are shown in Table 3.

Examples 15-17

Examples 15 to 17 were in accordance with Example 1 except that the amount of discharge of the core component polyester and the sheath component polyester was changed and the core: sheath ratio shown in Table 3 was changed. The evaluation results are shown in Table 3.

1 core ingredient
2 second component
Center position of three core components
4 Central location of composite fibers
5 Radius of Composite Fiber
10 Heat-sealable core-sheath composite fiber

Claims (3)

A core-sheath type conjugate fiber made of polyester with a melting point of 250°C or higher as the core and a polyester sheath with a melting point of 215°C or higher and a melting point lower than that of the polyester constituting the core by 20 to 35°C, and having a strength of 3.8 cN/dtex or higher. , Elongation is 35% or more and 50% or less, and the sheath contains 0.05% by weight or more and 0.5% by weight or less of inorganic fine particles. According to claim 1,
A heat-sealable core-sheath-type composite fiber in which the total fineness of the core-sheath-type composite fiber is 30 dtex or more and the single yarn fineness is 3.0 dtex or less. A tricot knitted fabric comprising the heat-sealable core-sheath type composite fiber according to claim 1 or 2.

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