Patent Application
20230332336
This disclosure relates to a polyester fiber having hygroscopicity.
Polyester fibers typified by polyethylene terephthalate are widely used in clothing applications and industrial applications because of their characteristics such as having excellent mechanical properties, chemical resistance, and heat resistance, having characteristic texture with tension and stiffness, hardly absorbing moisture and having small change in properties with wet, and having excellent dimensional stability. However, as described above, polyester fibers do not have hygroscopicity, and they have a problem of getting sweaty or sticky particularly in a high-temperature and high-humidity environment in summer. Thus, a composite fiber with a polymer having hygroscopicity to impart hygroscopicity to a polyester fiber has been proposed.
For example, Japanese Patent Laid-open Publication No. 2016-69770 proposes a sea-island composite fiber having hygroscopicity in which polyethylene terephthalate is used as a sea part and a polyether block amide copolymer is used as an island part.
International Publication No. 2018/012318 proposes a sea-island composite fiber in which hygroscopicity is imparted to a fiber by using a polymer having hygroscopicity in an island part, and the thickness of a sea part present in an outermost layer in a transverse section of the fiber is controlled to reduce breaking of the sea part in a hot water treatment.
In the sea-island composite fibers disclosed in JP '770 and WO '318, the thickness of the sea part and the number of the island parts are defined regarding the arrangement of the island parts in a transverse section of the fiber, but when the single fiber fineness is reduced to obtain a soft texture required for clothing applications, stress generated with volume swelling of the polymer having hygroscopicity in a hot water treatment cannot disperse, and breaking such as cracks may occur in the fiber surface. Thus, the quality of a woven or knitted fabric or the like may degrade because of generation of dyeing unevenness, fuzz, and the like. Further, there is also a problem of elution of the polymer having hygroscopicity because of surface breaking of the fiber, which lowers the hygroscopicity. In addition, in such fibers, the fiber surface may break when the fibers or a textile made of the fibers are worn, which has been a problem in applying the fibers to clothing that is repeatedly washed such as an inner, clothing that is repeatedly abraded such as sports clothing and the like.
There is thus a need to address the above problems, in which breaking of the fiber surface is dramatically reduced by dispersing the stress generated with volume swelling of the fiber at the time of moisture absorption. It could therefore be helpful to provide a polyester fiber free from dyeing unevenness, fuzz and the like when formed into a woven or knitted fabric, has excellent quality, and does not decrease its hygroscopicity because of a hot water treatment or the like.
We thus provide:
Our composite fibers, in which stress generated with volume swelling of the fiber at the time of moisture absorption can be dispersed and breaking of the fiber surface is reduced, is free from dyeing unevenness, fuzz, and the like when it is formed in a woven or knitted fabric, with which a polyester fiber excellent in quality can be obtained. In addition, since the hygroscopicity does not degrade, the fiber has excellent hygroscopicity, and it can be suitably used particularly in clothing applications.
Our polyester fiber includes an aromatic polyester as a main component. Having an aromatic polyester as the main component allows the polyester fiber to have excellent mechanical properties and heat resistance, and thus the polyester fiber has a favorable tactile sensation such as tension, stiffness, and dry feeling. Further, since the polyester fiber has excellent hygroscopicity with a moisture absorption/release parameter ΔMR of 2.0% or more, the polyester fiber can obtain a fiber structure body excellent in wearing comfort as a cooling material.
The fiber having hygroscopicity incorporates water molecules through physical adsorption of water molecules to the fiber and/or formation of an interaction between a functional group in a molecular structure of a component constituting the fiber and water molecules. In particular, when the fiber has high hygroscopicity, water molecules are incorporated into the fiber, and thus the fiber is swollen in volume. However, aromatic polyesters, which have rigid aromatic rings in their polymer structures, are hardly deformed, and stress generated with volume swelling due to moisture absorption cannot disperse, which may cause cracks and the like in the fiber surface.
Thus, in the polyester fiber that reduces breaking of the fiber surface with volume swelling at the time of moisture absorption, it is important that the centroids of the components disposed on the outermost periphery among the components disposed inside the fiber in a transverse section of the fiber form a regular polygon with line segments connecting the centroids as vertexes.
The sectional form of the fiber having components disposed inside the fiber in a transverse section of the fiber is preferably a sea-island composite fiber composed of two or more polymers, and the components disposed inside the fiber is island parts. The figure obtained by connecting the centroids of the components disposed on the outermost periphery among the components disposed inside the fiber in a transverse section of the fiber, that is, the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery in a transverse section of the fiber with line segments, is drawn by selecting the centroids such that the line segments do not intersect with each other except for the centroids as shown in
The definition of the regular polygon that is the disposition form of the island components as a feature of our fiber will be described.
Regarding the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery in a transverse section of the fiber with line segments, a figure formed by n line segments is an n-sided polygon, and the length of each line segment is A1, A2, A3 . . . An. When the average value of the lengths of these line segments is Lx, the ratio (A1/Lx, A2/Lx, A3/Lx . . . An/Lx) of the length of each line segment to the average value Lx is obtained by rounding off the ratio to the second decimal place, and the ratio is 0.97 to 1.03, it means that the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery in a transverse section of the fiber with line segments is a regular n-sided polygon.
In the polyester fiber, since the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery in a transverse section of the fiber with line segments is a regular polygon having the centroids as vertexes, vectors of stress generated when the fiber swells in volume because of moisture absorption are diametrically opposite between adjacent island parts, and the stress is canceled between the island parts, which can reduce stress to propagate to the sea part on the fiber surface side. Because the stress to propagate to the sea part on the fiber surface side is reduced, the fiber surface hardly breaks, and generation of dyeing unevenness and fuzz can be reduced. On the other hand, when the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery in a transverse section of the fiber with line segments is not a regular polygon having the centroids as vertexes, stress generated with volume swelling at the time of moisture absorption is less likely to disperse, and a point at which stress is concentrated is likely to be generated at the interface between the island parts and the sea part. For this reason, the fiber surface may break, dyeing unevenness and fuzz may be generated, and the quality of a woven fabric or a knitted fabric may degrade.
As described above, in the polyester fiber, the island components disposed on the outermost periphery are disposed in a regular polygon to greatly improve the problem in the conventional composite fiber having a hygroscopic component, and the number of island parts disposed on the outermost periphery in a transverse section of the fiber is preferably an odd number.
Setting the number of island parts disposed on the outermost periphery to an odd number can reduce concentration of stress generated with volume swelling due to moisture absorption in a linear shape, can disperse the stress, and can reduce breaking of the fiber surface. Thus, the fiber can reduce generation of dyeing unevenness and fuzz caused by breaking of the fiber surface and obtain excellent quality when the fiber is formed into a woven or knitted fabric. The number of island parts disposed on the outermost periphery in a transverse section of the fiber is more preferably an odd number of 9 or less, still more preferably an odd number of 5 or less, and the minimum number of the island parts is 3.
In the polyester fiber, the total number of the island parts in a transverse section of the fiber is preferably 15 or less. Setting the total number of the island parts in such a range can reduce concentration of stress generated with volume swelling due to moisture absorption in a linear shape, can disperse the stress, and can reduce breaking of the fiber surface. Thus, the fiber can reduce generation of dyeing unevenness and fuzz caused by breaking of the fiber surface and obtain excellent quality when the fiber is formed into a woven or knitted fabric. The total number of the island parts in a transverse section of the fiber is more preferably 10 or less, still more preferably 6 or less, and the minimum number of the island parts is 3.
In the polyester fiber, a ratio C/L of the radius of curvature C (μm) of a side on the fiber surface side of the outer periphery of an island part disposed on the outermost periphery in a transverse section of the fiber to the radius L (μm) of a circumscribed circle including the island parts disposed on the outermost periphery in a transverse section pf the fiber is preferably 0.50 to 0.90. The circumscribed circle including the island parts disposed on the outermost periphery in a transverse section of the fiber is the circle 4 in
C/L indicates the sharpness of the curve of the side on the fiber surface side of the outer periphery of the island part disposed on the outermost periphery in a transverse section of the fiber with respect to the fiber surface. When C/L is 0.50 or more, stress generated with volume swelling at the time of moisture absorption is uniformly applied and dispersed in the sea part, and the fiber surface hardly breaks. C/L is more preferably 0.55 or more, still more preferably 0.60 or more. When C/L is 0.90 or less, the curve of the side part on the fiber surface side of the outer periphery of the island part disposed on the outermost periphery in a transverse section of the fiber does not become large, and no corners are formed. Thus, stress generated with volume swelling at the time of moisture absorption does not concentrate on these parts, and the fiber surface hardly breaks. C/L is more preferably 0.85 or less, still more preferably 0.80 or less. The fact that C/L is 1.0 indicates that the bending of the fiber surface is equivalent to the curve of the side on the fiber surface side of the outer periphery of the island part disposed on the outer periphery. A specific example of a transverse section of the fiber includes a core-sheath composite fiber having one island part.
In the polyester fiber, the ratio L/R of the radius L (μm) of the circumscribed circle including all the island parts disposed on the outermost periphery in a transverse section of the fiber to the fiber radius R (μm) is preferably 0.50 to 0.90.
L/R indicates the thickness of the sea part between the fiber surface and the island parts disposed on the outermost periphery in a transverse section of the fiber. When L/R is 0.90 or less, the thickness of the sea part is sufficiently secured with respect to the fiber diameter. Thus, breaking of the sea part due to the stress generated with volume swelling at the time of moisture absorption can be reduced, generation of dyeing unevenness and fuzz due to breaking of the fiber surface caused by breaking of the sea part can be reduced, and the fiber has excellent quality when formed into a woven or knitted fabric. Based on this idea, L/R is more preferably 0.80 or less, still more preferably 0.60 or less. When L/R is 0.50 or more, the rigidity with the thickness of the aromatic polyester disposed in the sea part can be reduced, and stress generated with the volume swelling at the time of moisture absorption can be reduced.
In the polyester fiber, a ratio S/L of the minimum distance S (μm) between island parts in a transverse section of the fiber to the radius L (μm) of the circumscribed circle including all the island parts disposed on the outermost periphery in the transverse section of the fiber is preferably 0.05 to 0.50. The minimum distance between island parts in a transverse section of the fiber is the line segment 7 in
The minimum distance between the island parts in a transverse section of the fiber is the thickness of the sea parts sandwiched between two adjacent island parts. When S/L is 0.05 or more, stress generated with volume swelling at the time of moisture absorption is relaxed in the sea part between the island parts, propagation of stress to the sea part is reduced, and breaking of the fiber surface can be reduced. S/L is more preferably 0.10 or more, still more preferably 0.15 or more. When S/L is 0.50 or less, since the distance between island parts is not long, a stress relaxation effect by the sea part between the island parts is exhibited, propagation of stress to the sea part on the fiber surface side can be reduced, and breaking of the fiber surface can be reduced. Based on this idea, S/L is more preferably 0.40 or less, still more preferably 0.30 or less.
In the polyester fiber, the minimum thickness of the sea part is preferably 0.3 μm or more.
The minimum thickness of the sea part is the smallest distance among the distances between the intersection of a straight line and the outer periphery of any island part and the intersection of the straight line and any fiber surface, the straight line being drawn from the centroid of the island part in a transverse section of the fiber toward the fiber surface by the method described in Examples. The minimum thickness is the length of the line segment 6 in
The composite ratio of the sea part/island part of the polyester fiber is preferably 50/50 to 90/10 in terms of weight ratio. When the proportion of the sea part is 50 wt % or more, the aromatic polyester of the sea part provides excellent mechanical properties and heat resistance, tension, stiffness, and dry feeling, and a fiber structure body excellent in wearing comfort can be obtained. In addition, breaking of the sea part due to stress generated with volume swelling at the time of moisture absorption can be reduced, and generation of dyeing unevenness and fuzz due to breaking of the fiber surface caused by breaking of the sea part is reduced, and the fiber has excellent quality when formed into a woven or knitted fabric. The proportion of the sea part is more preferably 60 wt % or more, still more preferably 70 wt % or more. When the proportion of the sea part of the polyester fiber is 90 wt % or less, that is, the proportion of the island part is 10 wt % or more, the rigidity with the thickness of the aromatic polyester disposed in the sea part can be reduced, and stress generated with volume swelling at the time of moisture absorption can be reduced. Based on this idea, the proportion of the sea part is more preferably 85 wt % or less, still more preferably 80 wt % or less.
The polyester fiber has a moisture absorption/release parameter ΔMR, which is an index of hygroscopicity, of 2.0% or more. ΔMR is a difference in the moisture absorption rate of a fiber at a high temperature and a high humidity represented by 30° C.×90% RH and at a temperature and a humidity in a standard state represented by 20° C.×65% RH, and the higher ΔMR is, the higher the hygroscopicity of the fiber is. When ΔMR is 2.0% or more, stuffy feeling in clothes is small, and wearing comfort is exhibited. The range of ΔMR is more preferably 2.5% or more, still more preferably 3.0% or more, and particularly preferably 4.0% or more. There is no particular upper limit to the range of ΔMR, but the level that can be achieved is about 10%, which is a substantial upper limit. The polyester fiber satisfies the above-described range of ΔMR before and after a hot water treatment such as dyeing.
The aromatic polyester as the main component of the polyester fiber is a polymer composed of a combination of an aromatic dicarboxylic acid and an aliphatic diol, an aliphatic dicarboxylic acid and an aromatic diol, and an aromatic dicarboxylic acid and an aromatic diol. In general, from the viewpoint of mechanical properties, heat resistance, and handleability in production, it is preferable to use an aromatic polyester composed of a combination of an aromatic dicarboxylic acid and an aliphatic diol.
Specific examples of the aromatic dicarboxylic acid include, but are not limited to, terephthalic acid, isophthalic acid, phthalic acid, 5-sodium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid, 5-(tetraalkyl) phosphonium sulfoisophthalic acid, 4,4′-diphenyl dicarboxylic acid, and 2,6-naphthalene dicarboxylic acid.
Specific examples of the aliphatic diol include, but are not limited to, ethylene glycol, 1,3-propanediol, 1,4-butanediol, hexanediol, cyclohexanediol, diethylene glycol, hexamethylene glycol, and neopentyl glycol.
The method of producing the aromatic polyester is not limited, and the aromatic polyester may be produced by synthesizing monomers by a general polycondensation reaction, an addition polymerization reaction, or the like when raw materials at the time of production are comprehensively used as the monomers. The monomers are not limited, and examples thereof include petroleum-derived monomers, biomass-derived monomers, and mixtures of the petroleum-derived monomers and the biomass-derived monomers.
In addition, the aromatic polyester may be copolymerized or mixed with a second and third components in addition to the main component without departing from the desired effect. To have an aromatic polyester as the main constituent component, the copolymerization amount is 10 mol % or less as the monomer amount of the copolymerization component with respect to the total monomer amount.
In the polyester fiber, the main component of the sea part is an aromatic polyester as described above. However, aromatic polyesters typically do not have a functional group or the like that forms a strong interaction with water molecules in the polymer structure. Thus, as examples of the method of setting the ΔMR of the polyester fiber within the above range, adding a hygroscopic compound, disposing a polymer having high hygroscopicity (hereinafter, it may be referred to as hygroscopic polymer), treating polymer molecules on the fiber surface with ozone or the like to generate a hygroscopic functional group and the like are given. Of these, it is preferable to dispose a hygroscopic polymer in the island parts with consideration of obtaining a polyester fiber having excellent hygroscopicity.
Examples of the hygroscopic polymer suitably disposed in the island parts of the polyester fiber include polyether esters, polyether amides, polyether ester amides, polyamides, thermoplastic cellulose derivatives, and polyvinylpyrrolidone. Of these, polyether esters, polyether amides, and polyether ester amides containing a polyether as a copolymerization component are excellent in stability in melt molding, have high hygroscopicity which is intended, and are more preferably used for the polyester fiber. Further, polyether esters, having excellent affinity with the aromatic polyester in the sea part and excellent heat resistance of the hygroscopic polymer, have an effect of improving the mechanical properties of the resulting sea-island composite fiber, and they are particularly preferably used. In addition, a polyether ester composed of polybutylene terephthalate having excellent crystallinity and a polyether is more preferable since elution of the hygroscopic polymer into hot water can be reduced.
The hygroscopic polymer as described above has high affinity with water and is easily eluted when brought into contact with water or hot water in a dyeing treatment. When breaking of the fiber surface occurs because of stress generated with volume swelling at the time of moisture absorption, the hygroscopic polymer in the island parts may come into contact with hot water and elute off the fiber, leading to degradation of the hygroscopicity of the fiber. Thus, when the hygroscopic polymer is disposed in the island parts, the effect of reducing breaking of the fiber surface because of the composite sectional shape of the polyester fiber is remarkably exhibited, and a polyester fiber having excellent hygroscopicity is obtained.
In the hygroscopic polymer, the second and third components may be copolymerized or mixed in addition to the main component without departing from the desired effect, and the copolymerization amount is 10 mol % or less as the monomer amount of the copolymerization component with respect to the total monomer amount.
As the sectional shape of the polyester fiber, not only a round section but also a wide variety of sectional shapes such as a flat shape, a Y shape, a T shape, a hollow shape, a cross-in-square shape, and a shape like a hash tag, may be employed.
The polyester fiber may be in any form such as a long fiber (filament) or a short fiber (staple). In a long fiber, a monofilament composed of one single yarn or a multifilament composed of a plurality of single yarns may be used. In a short fiber, the cut length and the number of crimps are not limited.
The total fineness of the polyester fiber may be appropriately set according to the application, but it is preferably 8 dtex or more and 150 dtex or less in a long fiber for clothing in practice. The strength is preferably 1.5 cN/dtex or more for clothing, but the polyester fiber with a strength of 1.5 cN/dtex or less can also be used without any problems by taking measures such as using the fiber together with other fibers in producing a fabric. The elongation may be appropriately set according to the application, but it is preferably 25% or more and 60% or less from the viewpoint of processability in processing into a fabric.
The polyester fiber preferably has a single fiber fineness of 6.0 dtex or less. Having a single fiber fineness in such a range can reduce rigidity with the thickness of the aromatic polyester disposed in the sea part, and in addition, a fiber structure body having excellent mechanical properties and heat resistance, tension, stiffness, and dry feeling, and excellent wearing comfort can be obtained. In addition, breaking of the sea part due to stress generated with volume swelling at the time of moisture absorption can be reduced, and generation of dyeing unevenness and fuzz due to breaking of the fiber surface caused by breaking of the sea part is reduced, and the fiber has excellent quality when formed into a woven or knitted fabric. The single fiber fineness is more preferably 4.0 dtex or less, still more preferably 2.0 dtex or less.
The polyester fiber may be obtained by known methods of melt spinning and composite spinning, and examples thereof are as follows. The spinning method and the composite method are not limited to those exemplified herein.
The polyester fiber composed of two or more polymers may be produced by a melt spinning method for the purpose of producing a long fiber, a solution spinning method such as a wet method or a dry-wet method, a melt blowing method and a spunbonding method suitable for obtaining a sheet-shaped fiber structure, or the like, and the melt spinning method is suitable from the viewpoint of enhancing productivity. In the melt spinning method, it is preferable to use a composite spinneret described later. When the melt spinning method is used, the spinning temperature at that time is set to a temperature at which a polymer having a high-melting point or a high-viscosity polymer among polymer types to be used exhibits fluidity. The temperature at which the polymer exhibits fluidity varies depending on the molecular weight, but when the temperature is set between the melting point of the polymer and the melting point+60° C., the fiber can be stably produced.
A production method by a melt spinning method includes, for example, separately melting a polymer in the sea part and a polymer in the island part, measuring and transporting them by using a gear pump, forming a composite flow to have a specific composite structure as it is by an ordinary method, and discharging the composite flow from a spinneret, cooling a thread to room temperature by blowing cooling air with a thread cooling device such as a chimney, converging the thread with a supply of oil from an oil supply device, entangling the thread with a fluid entangling nozzle device, and passing the thread through a take-up roller and a stretching roller, and then stretching the thread according to a ratio of peripheral speeds of the take-up roller and the stretching roller. Further, the method includes thermally setting the thread with a stretching roller and winding the thread with a winder (winding device). There is also a two-step method in which the circumferential speeds of the take-up roller and the stretching roller are set to the same speed, and the thread is wound with a winder at the same speed to once form an unstretched yarn, and the yarn is stretched in a separate step.
In the polyester fiber, when the melt viscosity ratio of two or more polymers used in the sea part and the island part is less than 5.0, a composite polymer flow can be stably formed, and a fiber having a good composite section can be obtained, which is preferable.
As the composite spinneret used in production of the polyester fiber, a composite spinneret described in Japanese Patent Laid-open Publication No. 2011-208313 is preferably used. The composite spinneret shown in
Of the spinneret members shown in
Although not shown in
The polyester fiber can be subjected to post-processing such as false twisting or twisting, and it can be handled for weaving and knitting in the same manner as in n fibers.
The polyester fiber and/or its post-processed yarn may be formed into a fiber structure such as a woven fabric, a knitted fabric, a pile fabric, a nonwoven fabric, a spun yarn, or batting according to a known method. The fiber structure composed of the polyester fiber and/or its post-processed yarn may be any woven or knitted structure. A plain weave, a twill weave, a satin weave, or a weave changed from these weaves; or warp knitting, weft knitting, circular knitting, lace stitching, knitting or stitching changed from these knitting or stitching or the like can be suitably employed.
Our polyester fiber may be combined with other fibers by union weaving or union knitting in the formation of the fiber structure, or it may be combined with other fibers to form a combined filament yarn and then the combined filament yarn may be formed into a fiber structure.
The fiber structure body composed of the polyester fiber and/or its post-processed yarn is excellent in hygroscopicity, and therefore it can be suitably used in applications requiring comfort and quality. Examples of the applications include, but are not limited to, general clothing applications, sports apparel applications, bedding applications, interior applications, and materials applications.
Our composite fibers and fiber products will be described in detail with reference to Examples, but this disclosure is not limited to the Examples. Each property value in Examples was obtained by the following method.
A polymer sample having a moisture content set to 300 ppm or less with a vacuum dryer was put into a heating furnace set at the same temperature as the spinning temperature, melted under a nitrogen atmosphere, and extruded from a capillary at the tip of the heating furnace while changing the strain rate stepwise, then the viscosity was measured with Capilograph manufactured by Toyo Seiki Seisaku-sho, Ltd. The measurement was started after the sample was put into the heating furnace and left for 5 minutes, and the value at a shear rate of 1216 sec−1 was taken as the melt viscosity of the polymer.
Using a differential scanning calorimeter (DSC) model Q2000 manufactured by TA instruments, 20 mg of the polymer sample was heated from 20° C. to 300° C. at a temperature rising rate of 20° C./min, held at 300° C. for 5 minutes, then cooled from 300° C. to 20° C. at a temperature falling rate of 20° C./min, held at a temperature of 20° C. for 1 minute, and further heated from 20° C. to 280° C. at a temperature rising rate of 20° C./min. A peak top temperature of an endothermic peak then observed was defined as the melting point. When a plurality of endothermic peaks were observed, the endothermic peak top on the highest temperature side was taken as the melting point.
A hank was made by winding the sample yarn 200 times using a wrap reel with a frame circumference of 1.125 m, the hank was dried with a hot-air dryer (105±2° C.×60 minutes), then the hank was weighed with a balance, and the total fineness was calculated from a value obtained by multiplying the weight by official moisture regain. The measurement was performed four times, and the average was defined as the total fineness.
A measurement was performed under a constant rate of extension conditions shown in JIS L1013 (chemical fiber filament yarn test method, 2010) using “TENSILON” (registered trademark) UCT-100 manufactured by ORIENTEC CORPORATION as a measuring instrument. The elongation was calculated from the elongation at the point showing maximum strength in the tensile strength-elongation curve. The tensile strength was defined as the value obtained by dividing the maximum strength by the total fineness. The measurement was performed 10 times, and the average was defined as the tensile strength and the elongation.
A hank was made by winding the fiber sample 20 times using a warp reel with a frame circumference of 1.125 m, and an initial length L0 of the sample was determined under a load of 0.09 cN/dtex. Next, the sample was treated in boiling water under no load for 30 minutes, and then air-dried. Subsequently, a length L1 of the sample after the treatment under a load of 0.09 cN/dtex was obtained, then calculated with Formula (1):
Boiling water shrinkage percentage (%)=[(L0−L1)/L0]×100 (1).
About 1 to 2 g of the fiber sample or a fabric sample was weighed in a weighing bottle, dried at 110° C. for 2 hours, and then the mass was measured, and this mass was defined as w0. Next, the dried fiber sample was held at a temperature of 20° C. and a relative humidity of 65% for 24 hours, and then the mass was measured, and this mass was defined as w65%. Subsequently, the temperature was adjusted to 30° C. and the relative humidity was adjusted to 90%, the fiber sample was held for 24 hours, the mass was then measured, and this mass was defined as w90%:
MR1=[(w65%−w0)/w0]×100 (2)
MR2=[(w90%−w0)/w0]×100 (3)
ΔMR=MR2−MR1 (4).
At this time, the value calculated from Formulas (2) to (4) was defined as ΔMR.
G. ΔMR after Hot Water Treatment
A tubular knitting was produced by adjusting the fiber sample to have a density of 50 using a circular knitting machine NCR-BL (pot diameter 3 inch and half (8.9 cm), 27 gauge) manufactured by EIKO INDUSTRIAL CO., LTD. When the regular fineness of the fiber was less than 80 dtex, the fiber was appropriately combined so that the total fineness of the fiber to be fed to the tubular knitting machine was 80 to 160 dtex, and when the total fineness was more than 80 dtex, one yarn was fed to the tubular knitting machine, and the tubular knitting was produced by adjusting the fiber sample to have the density of 50 as described above. Next, the obtained tubular knitting was charged into an aqueous solution containing sodium carbonate at 1 g/L and a surfactant SUNMORL BK-80 manufactured by NICCA CHEMICAL, CO., LTD, treated for 20 minutes with the aqueous solution whose temperature was raised to 80° C., and then dried in a hot air dryer at 60° C. for 60 minutes. The tubular knitting after drying was subjected to a hot water treatment under the conditions of a bath ratio of 1:100, a treatment temperature of 130° C., and a treatment time of 60 minutes, and then dried in a hot air dryer at 60° C. for 60 minutes to obtain a tubular knitting after the hot water treatment. For the obtained tubular knitting after the hot water treatment, ΔMR was calculated according to the description of item F.
The fiber sample was embedded in an embedding agent such as an epoxy resin, and an image was taken at a magnification at which 10 or more single fibers can be observed with a scanning electron microscope (SEM) manufactured by HITACHI, Ltd. in a fiber transverse section in a direction perpendicular to the fiber axis. The obtained image was analyzed using computer software WinROOF manufactured by MITANI CORPORATION to determine the radius of curvature C of a side on the fiber surface side of the outer periphery of the island part disposed on the outermost periphery in the fiber transverse section.
In obtaining the radius of curvature, first, with reference to
In the same manner as in the item H, an image of a transverse section of the fiber was taken by SEM, the image taken with WinROOF was analyzed, the radius of the circumscribed circle including all the island parts disposed on the outermost periphery in the transverse section of the fiber was measured up to the third decimal place, a simple number average of the results of performing this operation on 10 single fibers randomly extracted was obtained, then the value obtained by rounding off to the second decimal place was taken as the radius L (μm) of the circumscribed circle.
In the same manner as in the item H, an image of a transverse section of the fiber was taken by a SEM, radiuses of single fibers randomly extracted in the same image from each taken image were measured to the third decimal place in units of μm, a simple number average of results of performing this operation on 10 single fibers randomly extracted was obtained, then a value obtained by rounding off to the second decimal place was taken as the fiber radius R (μm). When the transverse section of the fiber in a direction perpendicular to the fiber axis was not a perfect circle, the area thereof was measured, and a value obtained by converting it into a circle was employed.
In the same manner as in the item H, an image of a transverse section of the fiber was taken by SEM, and the image taken with WinROOF was analyzed to determine the minimum distance S between island parts in the transverse section of the fiber.
In obtaining the minimum distance between island parts, with reference to
In the same manner as in the method of obtaining the length of the line segment BF described in the item H, with reference to
A tubular knitting produced by the method described in the item G and subjected to the hot water treatment was vapor-deposited with a platinum-palladium alloy and observed at a magnification of 1,000 using scanning electron microscope (SEM) S-4000 manufactured by HITACHI, Ltd., and micrographs of 10 fields were randomly taken. In the obtained 10 photographs, the fiber surface constituting the tubular knitting was observed, and the points where the sea part was broken were counted. When the number of breaks of the sea part was 10 or less, it was regarded as pass.
A tubular knitting was produced by the method described in the item G, and the obtained tubular knitting was charged into an aqueous solution containing sodium carbonate at 1 g/L and a surfactant SUNMORL BK-80 manufactured by NICCA CHEMICAL, CO., LTD, treated for 20 minutes with the aqueous solution whose temperature was raised to 80° C., and then dried in a hot air dryer at 60° C. for 60 minutes. Next, the tubular knitting was subjected to dry heat setting at 160° C. for 2 minutes. The tubular knitting after the dry heat setting was charged into a dyeing solution in which 1.3 wt % of Kayalon Polyester Blue UT-YA manufactured by NIPPON KAYAKU, Co., Ltd. was added as a disperse dye to adjust the pH to 5.0, or into a dyeing solution in which 1.0 wt % of Kayacryl Blue 2RL-ED manufactured by NIPPON KAYAKU, Co., Ltd. was added as a cationic dye to adjust the pH to 4.0, and dyed under the conditions of a bath ratio of 1:100, a dyeing temperature of 130° C., and a dyeing time of 60 minutes.
Using the tubular knitting after dyeing as a sample, the L value was measured three times per sample using a spectrophotometer CM-3700d manufactured by Minolta Co., Ltd. with a D65 light source and a viewing angle of 10° under an optical condition of SCE (specular component excluded), and the average value thereof was rounded off to the first decimal place to obtain the L value of the sample. This operation was performed on 10 samples randomly extracted, and the variation rate was obtained from the average value and standard deviation of the L values of 10 samples. When the variation rate of the L value of the 10 samples was 5.0% or less, it was determined that there was no dyeing unevenness.
Using a multipoint fuzz counting apparatus (MFC-120 manufactured by TORAY ENGINEERING Co., Ltd.), the fiber sample was run at 600 m/min and measured for 10,000 m, and the fuzz number displayed on the apparatus was counted. A warping reed (made of stainless steel, with an interval of 1 mm between reeds) was provided before the measurement point, and the fiber was passed therethrough. This measurement was repeated 10 times, the average value at 10,000 m was taken as the fuzz number, and when the fuzz number was 10/10,000 m or less, it was regarded as pass.
A tubular knitting produced by the method described in the item G and subjected to the hot water treatment was held at a temperature of 20° C. and a relative humidity of 65% for 24 hours, and then the mass thereof was measured and taken as wa. Next, 0.3 ml of water was dripped to the center of the sample, and the mass was measured. This mass was defined as w0min. The moment when water was dripped to the sample was defined as 0 minutes, the mass of the sample was measured at intervals of 5 minutes, and the mass was defined as wnmin. n minutes represents a freely-selected time at which the mass of the sample was measured, having 5 minutes of intervals such as 5 minutes, 10 minutes, and 15 minutes. The moisture residual ratio WR at the free-selected time was calculated from Formula (5):
WR=[(w0min−wnmin)/(w0min−wa)]×100 (5).
When the time at which the moisture residual ratio WR calculated from Formula (5) was less than 30% was 60 minutes or less, it was determined that the sample has water-absorbing and quick-drying properties.
Change in hygroscopicity of the fiber before and after the hot water treatment was evaluated with a difference in ΔMR obtained by subtracting ΔMR before the hot water treatment calculated in the item F from ΔMR after the hot water treatment calculated in the item G. When the change in ΔMR was 2.0% or less, it was considered that the hygroscopicity of the fiber was maintained before and after the hot water treatment.
Polyethylene terephthalate (melt viscosity: 120 Pa·s, melting point: 254° C.) was used as the sea part, and polybutylene terephthalate (melt viscosity: 50 Pa·s, melting point: 217° C.) copolymerized with 50 wt % of polyethylene glycol having a number average molecular weight of 8,300 g/mol (PEG6000S manufactured by Sanyo Chemical Industries, Ltd.) was used as the island part. The polymers for the sea part and the island part were separately melted at a spinning temperature of 285° C., and then weighed such that the sea-island ratio was 80:20 in terms of weight ratio. The polymers were allowed to flow into a spinning pack incorporating the composite spinneret shown in
A stretched yarn of polyester fiber of 84 dtex and 36 filaments was obtained under the same conditions as in Example 1, except that the sea part was changed to polyethylene terephthalate (melt viscosity: 170 Pa·s, melting point: 244° C.) copolymerized with 1.5 mol % of 5-sulfoisophthalic acid sodium salt and 1.0 wt % of polyethylene glycol having a number average molecular weight of 1,000 g/mol (PEG1000 manufactured by Sanyo Chemical Industries, Ltd.). For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios between the length of each line segment and the average value of the lengths of the line segments were 0.99, 1.02, and 0.99, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.
A stretched yarn of polyester fiber of 84 dtex and 72 filaments was obtained under the same conditions as in Example 2 except that the number of discharge holes was 72, a polyester fiber of unstretched yarn of 155 dtex and 72 filaments was obtained, and the obtained unstretched yarn was stretched at a stretch ratio of 1.84 times. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 0.99, 0.99, and 1.02, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.
A stretched yarn of polyester fiber of 84 dtex and 14 filaments was obtained under the same conditions as in Example 2 except that the number of discharge holes was 14, a polyester fiber of unstretched yarn of 258 dtex and 14 filaments was obtained, and the obtained unstretched yarn was stretched at a stretch ratio of 3.07 times. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 0.97, 1.00, and 1.03, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.
A stretched yarn of polyester fiber of 84 dtex and 72 filaments was obtained under the same conditions as in Example 3 except that the sea-island ratio was 50:50 in terms of weight ratio. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 1.00, 0.99, and 1.01, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.
A stretched yarn of polyester fiber of 84 dtex and 36 filaments was obtained under the same conditions as in Example 1 except that the sea part was changed to polyethylene terephthalate (melt viscosity: 40 Pa·s, melting point: 254° C.). For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 0.98, 1.03, and 0.99, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.
A stretched yarn of polyester fiber of 84 dtex and 72 filaments was obtained under the same conditions as in Example 3 except that the sea part was changed to polyethylene terephthalate (melt viscosity: 40 Pa·s, melting point: 254° C.), and the sea-island ratio was 50:50 in terms of weight ratio. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 1.03, 1.01, and 0.97, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.
A stretched yarn of polyester fiber of 66 dtex and 96 filaments was obtained under the same conditions as in Example 3 except that a polyester fiber of unstretched yarn of 115 dtex and 96 filaments was obtained with discharge holes having a hole diameter of 0.23 mm and the number of holes of 96, and the obtained unstretched yarn was stretched at a stretch ratio of 1.72. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 0.99, 1.01, and 0.99, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.
A stretched yarn of polyester fiber of 56 dtex and 144 filaments was obtained under the same conditions as in Example 3 except that a polyester fiber of unstretched yarn of 88 dtex and 144 filaments was obtained with discharge holes having a hole diameter of 0.20 mm and the number of holes of 144, and the obtained unstretched yarn was stretched at a stretch ratio of 1.57. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 0.98, 1.03, and 0.99, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.
Polyethylene terephthalate (melt viscosity: 68 Pa·s, melting point: 251° C.) copolymerized with 16 wt % of polyethylene glycol having a number average molecular weight of 8,300 g/mol (PEG6000S manufactured by Sanyo Chemical Industries, Ltd.) was used as the sea part, and polyethylene terephthalate (melt viscosity: 120 Pa·s, melting point: 254° C.) was used as the island part. The polymers for the sea part and the island part were separately melted at a spinning temperature of 285° C., and then weighed such that the sea-island ratio was 90:10 in terms of weight ratio. The polymers were allowed to flow into a spinning pack incorporating the composite spinneret shown in
Polyethylene terephthalate (melt viscosity: 170 Pa·s, melting point: 244° C.) copolymerized with 1.5 mol % of 5-sulfoisophthalic acid sodium salt and 1.0 wt % of polyethylene glycol having a number average molecular weight of 1,000 g/mol (PEG1000 manufactured by Sanyo Chemical Industries, Ltd.) was used as the sea part. Next, a polycaprolactam master chip was produced by adding 20 wt % of polyvinylpyrrolidone (“Luviskol” K30SP, K value=30, manufactured by BASF SE) to polycaprolactam containing no additives. Subsequently, the master chip was chip-blended with polycaprolactam (sulfuric acid relative viscosity: 2.71, melting point: 220° C.) containing no additives to prepare a polycaprolactam blended polymer having a polyvinylpyrrolidone additive rate of 5.0 wt %, and this blended polymer (melt viscosity: 130 Pa·s, melting point: 220° C.) was used as the island part. A stretched yarn of polyester fiber of 84 dtex and 36 filaments was obtained under the same conditions as in Example 1 except that the polymers were combined as the sea part and the island part, and the sea-island ratio was 50:50 in terms of weight ratio. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 0.98, 1.02, and 0.99, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.
A stretched yarn of polyester fiber of 84 dtex and 36 filaments was obtained under the same conditions as in Example 2 except that the island part was changed to “PEBAX MH1657” (melt viscosity: 45 Pa·s, melting point: 203° C.) manufactured by Arkema Inc. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 1.01, 1.01, and 0.98, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.
A stretched yarn of polyester fiber of 84 dtex and 72 filaments was obtained under the same conditions as in Example 3 except that the polymers were allowed to flow into a spinning pack incorporating the composite spinneret shown in
A stretched yarn of polyester fiber of 84 dtex and 36 filaments was obtained under the same conditions as in Example 2 except that the polymers were allowed to flow into a spinning pack incorporating the composite spinneret shown in
A stretched yarn of polyester fiber of 84 dtex and 36 filaments was obtained under the same conditions as in Example 2 except that the sea-island ratio was 65:35 in terms of weight ratio. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 1.01, 0.98, and 1.01, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.
Polyethylene terephthalate (melt viscosity: 120 Pa·s, melting point: 254° C.) was used as the sea part, and polybutylene terephthalate (melt viscosity: 50 Pa·s, melting point: 217° C.) copolymerized with 50 wt % of polyethylene glycol having a number average molecular weight of 8,300 g/mol (PEG6000S manufactured by Sanyo Chemical Industries, Ltd.) was used as the island part. The polymers for the sea part and the island part were separately melted at a spinning temperature of 285° C., and then weighed such that the sea-island ratio was 80:20 in terms of weight ratio. The polymers were allowed to flow into a spinning pack incorporating the composite spinneret shown in
A stretched yarn of polyester fiber of 84 dtex and 36 filaments was obtained under the same conditions as in Example 1 except that the sea part was changed to polyethylene terephthalate (melt viscosity: 500 Pa·s, melting point: 254° C.). For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, the ratios of the length of each line segment to the average value of the lengths of the line segments were 1.10, 1.04, and 0.86, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was not a regular triangle. Thus, the obtained polyester fiber had breaking of the sea part at the time of moisture absorption, and dyeing unevenness and fuzz were generated when the polyester fiber was formed into a fabric. In addition, the polymer of the island part was eluted from the broken part of the sea part, and the moisture absorption and release properties after the hot water treatment were also poor. The evaluation results of the obtained polyester fiber are shown in Table 3.
A stretched yarn of polyester fiber of 84 dtex and 36 filaments was obtained under the same conditions as in Example 1 except that the sea-island ratio was 40:60 in terms of weight ratio. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, the ratios of the length of each line segment to the average value of the lengths of the line segments were 1.09, 0.96, and 0.95, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was not a regular triangle. Thus, the obtained polyester fiber had breaking of the sea part at the time of moisture absorption, and dyeing unevenness and fuzz were generated when the polyester fiber was formed into a fabric. In addition, since the amount of polyethylene terephthalate in the sea part was small, the water-absorbing and quick-drying properties were poor. The evaluation results of the obtained polyester fiber are shown in Table 3.
A stretched yarn of polyester fiber of 84 dtex and 10 filaments was obtained under the same conditions as in Example 2 except that the number of discharge holes was 10, a polyester fiber of unstretched yarn of 270 dtex and 10 filaments was obtained, and the obtained unstretched yarn was stretched at a stretch ratio of 3.21 times. For a triangle obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments in a transverse section of the fiber of the obtained polyester fiber, we confirmed that the ratios of the length of each line segment to the average value of the lengths of the line segments were 0.98, 1.02, and 1.00, and the figure obtained by connecting the centroids of the island parts disposed on the outermost periphery with line segments was a regular triangle. However, the moisture absorption and release properties were poor since the sea part was thick, the fiber had rigidity since the single fiber fineness was large, and the texture of the obtained fabric was also poor. The evaluation results of the obtained polyester fiber are shown in Table 3.
The polyester fiber, in which stress generated with volume swelling of the fiber at the time of moisture absorption can be dispersed and breaking of the fiber surface is reduced, has excellent quality when formed into a woven or knitted fabric without having dyeing unevenness, fuzz, and the like. In addition, since the hygroscopicity does not degrade, the fiber has excellent hygroscopicity, and it can be suitably used particularly in clothing applications.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-149756 | Sep 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/032054 | 9/1/2021 | WO |
