Modified flat cross-section fiber, fabric, and fiber product

Abstract

The present invention addresses the problem of providing: a modified flat cross-section fiber having excellent heat-shielding properties, ultraviolet-shielding properties, transparency, and light-transmitting properties; a fabric; and a fiber product.　The present invention is: a modified flat cross-section fiber in which in the cross-sectional shape of the fiber, the number of linear sites having an inclination angle with respect to the longitudinal direction of the cross-section of the fiber is within the range of 6‒12, the flatness (A / B) is within the range of 3‒6, the degree of modification (B / C) is within the range of 2‒4.5, and the inclination angle (θs) is within the range of 30‒70°; a fabric containing the fiber; and a fiber product obtained using the fabric.

Description

Irregular flat cross-section fibers, fabrics, and textile products

[0001] The present invention relates to a modified flat cross section fiber, fabric, and textile product that are excellent in heat shielding properties, ultraviolet shielding properties, transparency prevention properties, and light transmission properties.

[0002] Conventionally, synthetic fibers such as polyester fibers have many excellent characteristics such as strength, dimensional stability, and easy care, and are used as fabrics in a wide range of applications, including clothing and industrial use. Furthermore, it has been proposed to modify the cross-sectional shape of single fibers of synthetic fibers in order to improve their properties (for example, Patent Documents 1 to 3).

[0003] Furthermore, because ultraviolet rays contained in sunlight can affect the human body and can cause deterioration of interior products and tatami mats in homes, it has been proposed to construct textile products such as lace curtains from polyester fibers containing inorganic ultraviolet absorbers / reflectors such as titanium dioxide, or organic ultraviolet absorbers, in order to block ultraviolet rays (e.g., Patent Documents 4 and 5).

[0004] However, fabrics using polyester fibers containing inorganic ultraviolet absorbers have the problem of blocking not only ultraviolet but also visible light, impairing lighting properties, while fabrics using polyester fibers containing organic ultraviolet absorbers have not yet been satisfactory in terms of heat insulation properties.

[0005] Japanese Patent Laid-Open No. 4-24214 WO99 / 47734 Pamphlet Japanese Patent Laid-Open No. 2005-330615 Japanese Patent Laid-Open No. 2006-299438 Japanese Patent Laid-Open No. 2024-02360

[0006] The present invention has been made in view of the above background, and an object of the present invention is to provide a modified flat cross section fiber, fabric, and textile product that are excellent in heat shielding properties, ultraviolet shielding properties, transparency prevention properties, and light transmission properties.

[0007] The present inventors have conducted extensive research to solve the above problems, and have thus completed the present invention. Thus, the following inventions are provided: 1. An irregular flat cross section fiber, characterized in that in the cross section of the fiber, the number of linear portions having an inclination angle with respect to the longitudinal direction of the cross section is in the range of 6 to 12, the flatness is in the range of 3 to 6, the irregularity is in the range of 2 to 4.5, and the inclination angle is in the range of 30° to 70°. 2. The irregular flat cross section fiber according to item 1 above, wherein the content of the matting agent is 3.0% by weight or less. 3. The irregular flat cross section fiber according to item 1 or 2 above, wherein the irregular flat cross section fiber is made of polyester, polyamide, or polyethylene. 4. A fabric comprising the modified flat cross section fiber according to any one of 1 to 3 above, which is a woven fabric having a cover factor (CF) of 1500 to 3500, or a knitted fabric having 10 to 50 courses / 2.54 cm and 9 to 30 wales / 2.54 cm, where the cover factor (CF) is defined by the following formula: CF = (DWp / 1.1). １／２ ×MWp+(DWf / 1.1) １／２ × MWf [DWp is the total warp fineness (dtex), MWp is the warp weave density (counts / 2.54 cm), DWf is the total weft fineness (dtex), and MWf is the weft weave density (counts / 2.54 cm)] 5. The fabric according to 4 above, which has a heat shielding property of 35% or more as measured in accordance with JIS L1951. 6. The fabric according to 4 or 5 above, which has an ultraviolet shielding property of 90% or more as measured in accordance with JIS L1925. 7. The fabric according to any one of 4 to 6 above, which has a light transmission property of 10% or more as measured in accordance with JIS L1913. 8. A textile product selected from the group consisting of curtains, tents, shoji paper, clothing, and hats, which is made using the fabric according to any one of 4 to 7 above.

[0008] According to the present invention, it is possible to obtain a modified flat cross section fiber, fabric, and textile product that are excellent in heat shielding properties, ultraviolet shielding properties, transparency prevention properties, and light transmission properties.

[0009] 1 is a diagram showing an example of the cross-sectional shape of a non-circular flat cross section fiber that can be used in the present invention. 2 is a diagram showing an enlarged schematic view of only a set of "straight portions" (V-shaped portions) of a non-circular flat cross section fiber that can be used in the present invention. 3 is a diagram showing an apparatus used in a heat insulation test (infrared lamp, 60°C method).

[0010] The modified flat cross section fiber of the present invention will be described in detail below. The modified flat cross section fiber of the present invention must satisfy all of the following requirements (1) to (4): (1) In a cross section perpendicular to the longitudinal direction of the fiber (the fiber axis direction), the cross section is composed of a plurality of linear segments, and the number of linear segments forming zigzag surfaces at an inclination angle relative to the longitudinal direction of the cross section (the direction of the long side of the circumscribing rectangle in the cross section) is within a range of 6 to 12. (2) The flatness (A / B) is within a range of 3 to 6. (3) The modification (B / C) is within a range of 2 to 4.5. (4) The inclination angle (zigzag surface angle) θs relative to the longitudinal direction of the fiber cross section (parallel plane) is within a range of 30° to 70°.

[0011] The modified flat cross section fiber of the present invention has a flat cross section with multiple zigzag faces with an inclination angle θs in the range of 30° to 70°, so that when light travels from the polymer forming the fiber to the air layer, the incident angle (θ0) tends to be equal to or greater than about 30°, which is the critical angle of the polymer. As a result, the total reflection condition is satisfied, whereby a portion of the light does not transmit into the air layer ahead in the traveling direction, and excellent transparency prevention and heat shielding properties are obtained.

[0012] This will be explained in more detail using Figure 1. Note that Figure 1 illustrates an example of a cross-sectional shape of the modified flat cross-section fiber having seven inclined surfaces (the number of linear portions), but this does not limit the scope of the present invention.

[0013] In Figure 1, A is the maximum length in the longitudinal direction of the cross section. The longitudinal direction of the cross section corresponds to the long side direction of a circumscribing rectangle drawn in a cross section perpendicular to the length direction of the fiber (fiber axis direction). B is the maximum width in the short side direction of the cross section. The short side direction of the cross section corresponds to the short side direction of a circumscribing rectangle drawn in a cross section perpendicular to the length direction of the fiber (fiber axis direction). C is the distance between the incisions in the short side direction of the cross section. θs represents the inclination angle of the zigzag portion (zigzag linear portion) with respect to the longitudinal direction of the cross section.

[0014] First, regarding requirement (1), the cross section of the irregular flat cross section fiber has a number of linear portions (number of zigzag surfaces) with an inclination angle relative to the longitudinal direction of the cross section within a range of 6 to 12 (preferably 6 to 10, most preferably 7). This is important for making the longitudinal direction of the cross section parallel to the planar direction of the fabric when this irregular flat cross section fiber is used to form a fabric such as a woven fabric, knitted fabric, or nonwoven fabric, thereby making it easier to achieve the total reflection condition. If the number of linear portions is less than 6, the number of reflective surfaces is reduced, making it difficult to achieve the flatness required by requirement (2), which is undesirable. On the other hand, if the number of linear portions is more than 12, both ends in the longitudinal direction of the cross section may become rounded or bent due to the Beyrles effect, making it difficult to achieve flatness and also making it difficult to align the orientation of the fiber cross sections within the plane of the fabric.

[0015] Next, regarding requirement (2), the flatness (A / B) is within the range of 3 to 6 (preferably 3.5 to 5.0). If the flatness (A / B) is less than 3, when a sheet-like object such as a fabric is formed using the irregular flat cross-section fiber, the cross-sections tend to be randomly oriented, which may result in insufficient light reflection on the fiber surface. On the other hand, if the flatness (A / B) exceeds 6, the orientation crystallinity of the polymer in the cross-section of the yarn formed during spinning and drawing may differ, which may result in poor spinnability. Furthermore, when the fiber is heat-treated in hot water, it may become seaweed-like, resulting in reduced reflective performance.

[0016] Regarding requirement (3), the irregularity (B / C) is the value obtained by dividing the length of the short side B in the short direction by the length C of the overlapping portion of the inclination, and represents the length contributing to the surface reflection of the inclined portion. A larger irregularity value results in a longer inclined portion contributing to the surface reflection of the fiber cross section, allowing for more efficient reflection of incident light. Therefore, it is important that the irregularity (B / C) is 2 to 4.5 (preferably 3 to 4.5). If the irregularity (B / C) is less than 2, the reflective surface is small, and sufficient effect may not be achieved. If the irregularity (B / C) is greater than 4.5, the inclined portion is likely to bend, which may deteriorate spinnability or cause the fiber to become seaweed-like when heat-treated in hot water, resulting in reduced reflective performance. Regarding requirement (4), the inclination angle (zigzag surface angle) θs is 30° to 70° with respect to the longitudinal direction of the fiber cross section.

[0017] Next, the principle of total reflection is shown in Figure 2. First, the conditional expression for when light from the polymer layer that constitutes the fiber is transmitted to the air layer is as follows (Equation 1): n0 sin θ0 = n1 sin θ1 (Equation 1)

[0018] Total reflection occurs when the angle of incidence is equal to or less than the critical angle of total reflection. The refractive index of the polymer constituting the fiber is n0, the refractive index of air is n1, the angle of incident light from the polymer layer to the interface with the air layer (incident angle, or incident light angle) is θ0, and the angle of transmitted light (transmission angle, or transmitted light angle) is θ1. This will be explained in detail below.

[0019] When the angle θ0 at which light travels through the fiber is the critical angle for total reflection calculated from the refractive index of the polymer that makes up the fiber and the refractive index of air, the light that travels from the polymer layer that makes up the fiber to the air layer passes almost along the straight part of the fiber ([Circle 2] in Figure 2: Total reflection). If the angle is small, the light is only bent slightly and transmits to the air layer ([Circle 1] in Figure 2: Transmission). On the other hand, if the angle is large, the light is totally reflected ([Circle 3] in Figure 2: Total reflection). In the present invention, total reflection refers to reflection that satisfies the conditions for total reflection.

[0020] For example, in the case of polyethylene terephthalate, the refractive index n0 of polyethylene terephthalate is 1.57, so the angle θ1 of transmitted light becomes 90° when the angle of incident light θ0 is 40°. Note that the refractive indexes of other fiber polymers are also within the range of about 1.55 to 1.65, and the angle of incidence θ0 (critical angle) at which the angle of transmission θ1 = 90° is approximately 40°.

[0021] When the incident angle is 40° or more, the total reflection condition is met and light does not transmit into the air layer. Therefore, one of the essential requirements of the present invention is that the angle θs of the inclined portion of the zigzag surface is set to 30° to 70° so that the incident angle θ0 is likely to be 40° or more.

[0022] If the angle θs of the inclined portion of the zigzag surface is smaller than 30°, light is likely to transmit through it. If θs is larger than 70°, the distance between adjacent inclined surfaces is small, which makes it easier for fusion between surfaces to occur during the spinning process, and there is a risk that a cross section that satisfies the requirements (2) and (3) may not be obtained.

[0023] Furthermore, by adopting such an angle for the inclined portion of the zigzag surface, even if the polymer does not contain (or contains only a small amount of) fine particles with a high refractive index such as titanium oxide, heat-shielding properties, ultraviolet-shielding properties, and transparency-blocking properties can be obtained while maintaining a moderate level of light transmission, unlike the dullness and opacity caused by the diffuse reflection phenomenon due to the fine particles.

[0024] In the modified flat cross section fiber of the present invention, the polymer constituting the fiber is preferably one that is easily light-transmitting or light-reflecting and can be melt-spun. Specifically, polyester, polyamide, or polyethylene is preferred. While composite fibers (conjugate fibers) containing the above polymers as one component may be used, they are preferably composed of a single polymer in terms of ease of shape retention. In the case of polyester, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polylactic acid, etc. are preferred. Furthermore, in the case of polyamide, nylon 6, nylon 66, etc. are preferred.

[0025] The polyester is further described. Polyesters are produced from a dicarboxylic acid component and a diglycol component. The dicarboxylic acid component is preferably primarily terephthalic acid. The diglycol component is preferably primarily one or more alkylene glycols selected from ethylene glycol, trimethylene glycol, and tetramethylene glycol. The polyester resin may also contain a third component in addition to the dicarboxylic acid component and glycol component. Examples of such a third component include an anionic component dyeable with a cationic dye (e.g., sodium sulfoisophthalic acid; dicarboxylic acids other than terephthalic acid, such as isophthalic acid, naphthalenedicarboxylic acid, adipic acid, and sebacic acid), and glycol compounds other than alkylene glycols (e.g., one or more of diethylene glycol, polyethylene glycol, bisphenol A, and bisphenol sulfone). Such polyesters may include material-recycled or chemically recycled polyesters, as well as polyethylene terephthalate, polylactic acid, and stereocomplex polylactic acid, which are produced using monomer components derived from biomass, i.e., biologically derived materials. Furthermore, polyesters obtained using a catalyst containing a specific phosphorus compound and a titanium compound, as described in JP-A Nos. 2004-270097 and 2004-211268, may also be used. Modified flat cross section fibers made of such polymers can be obtained by melt spinning, drawing, and heating.

[0026] Here, in the modified flat cross section fiber, it is preferable from the viewpoint of light transmission that the content of the matting agent (titanium oxide) contained in the fiber is 3.0% by weight or less (more preferably 0.5% by weight or less, even more preferably 0 to 0.4% by weight, and particularly preferably 0.001 to 0.1% by weight). If the content of the matting agent is greater than 3.0% by weight, the light transmission may be reduced. The content of the matting agent may be 0% by weight (i.e., no matting agent is contained). Note that the fiber may contain additives such as antioxidants, fluorescent brighteners, and flame retardants, as long as they do not impair the effects of the present invention.

[0027] In the irregular flat cross section fiber, an organic UV absorber may be contained in the polymer forming the fiber, or an organic UV absorber may be applied to the fiber or fabric to improve the UV shielding performance. When an organic UV absorber is contained in the irregular flat cross section fiber, the content must be limited so as not to interfere with the irregular cross section shape simultaneously satisfying the above requirements (1) to (4). A preferred range is 0.01 to 5.0 wt % (more preferably 0.05 to 2.0 wt %).

[0028] Examples of the organic UV absorber include benzoxazine-based organic UV absorbers, benzophenone-based organic UV absorbers, benzotriazole-based organic UV absorbers, benzoxazole-based organic UV absorbers, triazine-based organic UV absorbers, salicylic acid-based organic UV absorbers, etc. Among these, benzoxazine-based organic UV absorbers are particularly preferred because they do not decompose during the spinning stage.

[0029] Suitable examples of such benzoxazine-based organic UV absorbers include those disclosed in JP-A-62-11744, such as 2-methyl-3,1-benzoxazin-4-one, 2-butyl-3,1-benzoxazin-4-one, 2-phenyl-3,1-benzoxazin-4-one, 2,2'-ethylenebis(3,1-benzoxazin-4-one), 2,2'-tetramethylenebis(3,1-benzoxazin-4-one), 2,2'-p-phenylenebis(3,1-benzoxazin-4-one), 1,3,5-tri(3,1-benzoxazin-4-one-2-yl)benzene, and 1,3,5-tri(3,1-benzoxazin-4-one-2-yl)naphthalene.

[0030] The single fiber fineness of the modified flat cross section fiber is preferably within the range of 0.3 to 6.0 dtex (more preferably 0.5 to 3 dtex). If the single fiber fineness is less than 0.3 dtex, the yarn will be too thin, which may cause process defects such as the generation of fluff during yarn production, false twisting and crimping, and weaving and knitting, or may result in poor quality. If the single fiber fineness exceeds 6.0 dtex, the texture of the fabric may become particularly stiff.

[0031] Next, the fabric of the present invention contains the above-mentioned modified flat cross section fiber. In this case, it is preferable that a large number of modified flat cross section fibers are gathered together and contained in the fabric as a yarn (multifilament or spun yarn).

[0032] In this case, the total fineness of the yarn is preferably 20 to 300 dtex (more preferably 40 to 160 dtex). The number of filaments constituting the yarn is preferably 12 to 72 (more preferably 12 to 48). Furthermore, such yarn may be doubled or doubled or mixed with other yarns to form a thicker yarn. If the total fineness or number of filaments of the yarn is too small, productivity may decrease or the texture may become too soft. Conversely, if the total fineness or number of filaments of the yarn is too large, the texture of the fabric may become hard.

[0033] The toughness value of such yarn is preferably 10 or more (more preferably 10 to 40). If the toughness value is less than 10, the practical durability of the fabric made from the yarn may be low. The toughness value is calculated by the following formula: Toughness value = Breaking strength (cN / dtex) x (Breaking elongation (%)) １／２

[0034] In the fabric of the present invention, the modified flat cross section fiber is preferably contained in an amount of 30% by weight or more (more preferably 60 to 100% by weight, and particularly preferably 100% by weight) relative to the weight of the fabric. If the content is less than 30% by weight, the fabric may not be satisfactory in terms of heat shielding properties, opaque properties (image shielding properties), light transmission properties, and ultraviolet shielding properties.

[0035] The weave or knit structure of the fabric is not particularly limited, and may be one knitted or woven by a conventional method. Furthermore, it may be a nonwoven fabric. For example, examples of the weave structure of the fabric include three basic weaves such as plain weave (plain weave), twill weave (twill weave), and satin weave, as well as modified weaves, single double weaves such as warp double weave and weft double weave, and warp velvet. The type of knitted fabric may be a weft knit or a warp knit. Preferred examples of weft knit structures include plain knit, rib knit, double knit, purl knit, tuck knit, float knit, single rib knit, lace knit, and fringe knit. Preferred examples of warp knit structures include single denbigh knit, single atlas knit, double cord knit, half tricot knit, fleece knit, and jacquard knit. The number of layers may be a single layer or two or more layers.

[0036] When the fabric is a woven fabric, the cover factor (CF) calculated by the following formula is preferably 1500 to 3500. If the cover factor is less than 1500, the inter-weave voids in the fabric become large, and the heat shielding, transparency-proofing, and ultraviolet shielding properties may become insufficient. In terms of heat shielding, transparency-proofing, and ultraviolet shielding properties, the higher the cover factor, the better, but if it is more than 3500, the light transmission and softness of the fabric may be impaired. CF=(DWp / 1.1) １／２ ×MWp+(DWf / 1.1) １／２ ×MWf where DWp is the total warp fineness (dtex), MWp is the warp weave density (counts / 2.54 cm), DWf is the total weft fineness (dtex), and MWf is the weft weave density (counts / 2.54 cm).

[0037] Furthermore, when the fabric is a knitted fabric, it preferably has a density of 10 to 50 courses / 2.54 cm and 9 to 30 wales / 2.54 cm. If the density is lower than this range, the inter-woven voids in the knitted fabric will be large, and there is a risk that the heat shielding property, transparency prevention property, and ultraviolet shielding property will be insufficient. In terms of heat shielding property, transparency prevention property, and ultraviolet shielding property, the higher the density, the better, but if it is higher than this range, there is a risk that the light transmission property and softness of the fabric will be impaired.

[0038] The fabric of the present invention may be subjected to conventional dyeing and finishing processes, water-repellent processes, and nap-raising processes, as well as processes that impart functions such as ultraviolet screening agents, antibacterial agents, deodorizing agents, insect repellents, luminescent agents, retroreflective agents, and negative ion generators, within the scope of the present invention.

[0039] The fabric of the present invention has the above-described configuration and is therefore extremely excellent in heat shielding properties, ultraviolet shielding properties, transparency prevention properties, and light transmission properties. Here, the heat shielding properties measured according to JIS L1951 are preferably 35% or more (more preferably 38% or more). Furthermore, the ultraviolet shielding properties measured according to JIS L1925 are preferably 90% or more (more preferably 95 to 99.9%). Furthermore, the transparency prevention properties of the fabric measured according to the JIS L1923 transparency prevention test are preferably 80% or more (more preferably 82% or more, particularly preferably 85 to 99%).

[0040] The light transmission measured according to JIS L1913 is preferably 10% or more (more preferably 11 to 40%). Furthermore, the fabric of the present invention has a strong design potential, such as a sparkling reflective glossy appearance and a glittery feel. This is due to a particularly pronounced reflective effect and glossiness, which differs from the dullness and opacity caused by diffuse reflection of fine particles.

[0041] Next, the textile products of the present invention contain the above-mentioned fabric. Such textile products include curtains, tents, shoji paper, clothing, hats, etc. Since such textile products contain the above-mentioned fabric, they are extremely excellent in heat shielding, ultraviolet shielding, transparency prevention, and light transmission. In particular, lace curtains are preferred because the above-mentioned fabric is also excellent in privacy and transparency prevention.

[0042] The present invention will be described in more detail below with reference to the following examples. The various measurements mentioned in the following examples were determined by the following methods. (1) Intrinsic Viscosity (IV) of Polyester: A sample was dissolved in a mixed solvent of phenol:tetrachloroethane = 60:40 (mass ratio), and the intrinsic viscosity at 20°C was measured using an automatic viscosity measuring device ("ALC-6C" manufactured by Sun Electronics Industries Co., Ltd.) equipped with an Ubbelohde viscosity tube. (2) The cross-sectional shape of the fiber was observed at 400x magnification using an optical microscope for flatness. Here, the cross-sectional shape of the fiber is an image of a cross section perpendicular to the fiber axis of the target irregular flat cross section fiber. A is the maximum length in the longitudinal direction of the cross section of the irregular flat cross section fiber. B is the maximum width in the lateral direction of the cross section. Each length was measured, and the flatness was calculated using the following formula: Flatness = A / B. (3) The cross-sectional shape of the fiber was observed at 400x magnification using an optical microscope for flatness. B is as described above. C is the distance between the incisions in the cross-sectional short direction of the irregular flat cross-section fiber. Each length was measured, and the irregularity was calculated using the following formula: Irregularity = B / C (4) Angle θs of the inclined portion of the cross section The inclination angle θs of the zigzag inclined portion relative to the cross-sectional longitudinal direction was measured using an optical microscope at 400x magnification to observe the cross-sectional shape of the fiber. (5) Breaking strength and breaking elongation Breaking strength and breaking elongation were measured using a constant-speed extension tensile tester ("Tensilon" manufactured by Orientec Co., Ltd.) in accordance with the method described in JIS L1013, with a grip spacing of 20 cm and a pulling speed of 20 cm / min. (6) Total fineness and single fiber fineness The total fineness of the yarn was measured according to JIS-L-1013. The single fiber fineness was calculated by dividing this value by the number of single fibers in the yarn. (7) Fabric Weight: The fabric weight was measured according to JIS L1096 8.3.1 Correct Weight. (8) Fabric Transparency: The fabric weight was measured according to JIS L1923 Transparency Test.

[0043] (9) Thermal insulation of the fabric: The fabric was measured according to JIS L1951 heat insulation test (infrared lamp 60°C method). The thermal insulation test (infrared lamp 60°C method) was performed by hanging a test piece measuring approximately 50 cm x 40 cm in the apparatus shown in Figure 3, installing an infrared lamp approximately 50 cm away from the glass plate, and installing a black panel [1] 8 cm from the front side of the test piece and a temperature sensor [2] 4 cm from the wall opposite the glass surface. The infrared lamp was irradiated for 60 minutes, and the black panel temperature and the temperature inside the test chamber were measured every 5 minutes. A blank test was also conducted without hanging the test piece. The thermal insulation effect was calculated using the following formula from the maximum value of the blank test and the maximum value of the test piece. Test conditions: Ambient temperature: 25.0±1.0°C Initial temperature: Black panel 25.0±0.5°C Inside test chamber 25.0±0.5°C Effective blank test conditions: Maximum temperature rise on black panel 37.0±0.5°C Maximum temperature rise in test chamber 23.0±0.5°C Temperature rise difference X (°C) = Maximum temperature rise in blank test (°C) - Maximum temperature rise in test specimen test (°C) Insulation effectiveness rate (%) = X (°C) / Maximum temperature rise in blank test (°C) x 100 The insulation effectiveness rate (%) was calculated for each of [1] and [2] based on the values ​​measured by temperature sensors installed in the above [1] and [2] locations. (10) Two rooms separated by a fabric privacy window were prepared, with furniture installed in one room and facing indoors, and the other room facing outdoors. For the daytime test conditions, the outdoor side was brightly lit. Then, the sample (110 cm x 110 cm) was attached to a window frame, and the view inside the room was photographed from the outside with a camera. The obtained image was compared with a special scale to evaluate the difficulty of visibility inside the room. The scale grades the difficulty of visibility from 1 to 5, with grade 5 being the most difficult to see. Test conditions: Daytime test: Outdoor side: with lighting (1600 lx) - Indoor side: with lighting (500 lx) (11) Cover factor (CF) Calculated using the following formula: CF = (DWp / 1.1) １／２ ×MWp+(DWf / 1.1) １／２×MWf [DWp is the total warp fineness (dtex), MWp is the warp weave density (counts / 2.54 cm), DWf is the total weft fineness (dtex), and MWf is the weft weave density (counts / 2.54 cm).] (12) Heat shielding property (Examples 4 to 7 and Comparative Examples 6 and 7) Measured according to JIS L1951. (13) Light transmission property of fabric Light transmission property (%) was measured according to JIS L1913 Transmittance. (14) Ultraviolet shielding property of fabric Ultraviolet shielding property (%) was measured according to JIS L1925.

[0044] Example 1: Polyethylene terephthalate with an intrinsic viscosity of 0.65 dL / g and a titanium oxide (matting agent) content of 2.6 wt% in the polymer was used. After hot air drying at 160°C for 6 hours, the polymer was fed to a melt extruder to produce a 285°C molten polymer, which was then extruded from a spinneret equipped with 30 nozzles forming a modified cross section corresponding to the cross section shown in Figure 1. After extrusion, the polymer was cooled by horizontally blowing cold air at a temperature of 20°C and a humidity of 65% at a speed of 0.3 m / s from a position 120 mm below the spinneret. A 10% water emulsion finishing oil was then applied, and the polymer was taken up at a spinning speed of 1000 m / min, yielding an undrawn yarn with a total fineness of 235 dtex / 30 strands. The yarn was then stretched 2.8 times between a preheated roller at 85°C and a stretching roller at 130°C to obtain a yarn having a total fineness of 85 dtex / 30 strands and consisting of a modified flat cross section fiber having a cross section (seven straight lines) as shown in Figure 1. The properties of the fiber and yarn are shown in Table 1.

[0045] Next, using this yarn as the weft and a polyethylene terephthalate multifilament with a round cross section and a total fineness of 84 dtex / 36 strands and a titanium oxide (matting agent) concentration of 0.3 wt % twisted at 1000 turns / m as the warp, a plain weave fabric was produced with a weft density of 138 threads / 3.79 cm and a warp density of 132 threads / 3.79 cm. The resulting fabric was excellent in both heat-shielding and opacity prevention properties, and also in gloss. The evaluation results of the resulting fabric are shown in Table 2.

[0046] [Example 2, Comparative Examples 1 to 4] The spinneret used in Example 1 was changed, and the discharge holes were changed so as to have the cross-sectional shapes shown in Table 1. Except for changing the cross-sectional shapes, spinning was carried out under the same conditions as in Example 1 to obtain the yarns shown in Table 1.

[0047] Next, using these yarns as wefts and the same yarns as in Example 1 as warps, plain weave fabrics were produced in the same manner as in Example 1. The evaluation results of the fabrics are shown in Table 2.

[0048] In Example 2, both the heat-shielding property and the transparency-preventing property were good. In Comparative Example 1, the flatness A / B and the irregularity B / C, which indirectly represents the length of the inclined portion, were small, so there were single fibers whose longitudinal direction was not parallel to the fabric plane, and the reflective surface length was short, so sufficient reflective performance (heat-shielding property, transparency-preventing property) was not obtained. In Comparative Example 2, the inclination angle was 80° and the distance between the slit discharge holes forming the inclined surface was small, so the flatness and irregularity were small. As a result, it was difficult to align the fiber orientation, the inclined surface length was short, and a sufficient reflective surface was not obtained. In Comparative Example 3, the number of inclined surfaces was too small, so the desired performance was not obtained. In Comparative Example 4, the number of inclined surfaces was too large, so the flat cross section was curved or seaweed-like, and the inclination angle varied, so the desired performance was not obtained.

[0049] Comparative Example 5: The same polyethylene terephthalate as in Example 1 was prepared, with an intrinsic viscosity of 0.65 dL / g and a titanium oxide (matting agent) content of 2.6 wt% in the polymer. After 6 hours of hot air drying at 160°C, the polymer was fed to a melt extruder to produce a 285°C molten polymer, which was then extruded from a spinneret equipped with 72 round nozzles and cooled by horizontally blowing cold air at a temperature of 20°C and a humidity of 65% at a speed of 0.2 m / s from a position 120 mm below the spinneret. A 10% water emulsion finishing oil was then applied, and the resulting yarn was taken up at a spinning speed of 3000 m / min, yielding an intermediately oriented yarn with a total fineness of 123 dtex / 36 strands. The intermediately oriented yarn was then passed through a preheated heater zone at 200°C, where it was drawn at a draw ratio of 1.5 and simultaneously subjected to disk false twisting to obtain a false twisted crimped yarn (DTY yarn) with a total fineness of 83 dtex / 72 strands. The fiber and yarn properties are shown in Table 1.

[0050] Next, using this yarn as the weft and the same yarn as in Example 1 as the warp, a woven fabric was produced in the same manner as in Example 1. Although this woven fabric used ultrafine fibers with random crimping properties, light was transmitted through the gaps between the fibers, and sufficient reflective performance was not obtained. The evaluation results of the woven fabric are shown in Table 2.

[0051] Example 3 Melt spinning was performed in the same manner as in Example 1, except that polyethylene terephthalate was used, with a polymer intrinsic viscosity of 0.65 dL / g and a titanium oxide (matting agent) content of 0 wt% in the polymer. An undrawn yarn with a total fineness of 235 dtex / 30 strands was obtained. The yarn was then drawn 2.8 times between a preheated roller at 85°C and a drawing roller at 130°C, yielding a yarn with a total fineness of 83 dtex / 36 strands, consisting of a modified flat cross-section fiber having a cross-section as shown in Figure 1 (seven straight lines). The properties of the fiber and yarn are shown in Table 1.

[0052] Using this yarn, a monofilament having a fineness of 56 dtex, and a false twisted crimped yarn (DTY yarn) having a total fineness of 84 dtex / 72 strands, a raschel lace was produced at 28G 40 cpi. The weave structure and fabric properties are shown in Table 3.

[0053] The fabric obtained does not contain titanium oxide, but due to the total reflection function of the cross-sectional shape, it is able to exhibit good heat reflectivity and privacy. In addition, the reflected light gives it a sparkling luster and an appearance of reflected light.

[0054] [Comparative Example 6] Polyethylene terephthalate with an intrinsic viscosity of 0.65 dL / g and a titanium oxide (matting agent) content of 0 wt% in the polymer was used. After hot air drying at 160°C for 6 hours, it was fed into a melt extruder to produce a 285°C molten polymer. The polymer was extruded from a spinneret equipped with 36 Y-shaped nozzles forming a triangular cross section, and cooled by blowing cold air at a temperature of 20°C and a humidity of 65% horizontally at a speed of 0.3 m / s from a position 120 mm below the spinneret. A 10% water emulsion finishing oil was then applied, and the yarn was taken up at a spinning speed of 1000 m / min to obtain an undrawn yarn with a total fineness of 255 dtex / 36 strands. The yarn was then drawn 3.1 times between a preheated roller at 85°C and a drawing roller at 130°C to obtain a triangular cross section yarn with a total fineness of 83 dtex / 36 strands. The yarn properties are also shown in Table 1.

[0055] Using this yarn, a monofilament having a fineness of 56 dtex, and a false twisted crimped yarn (DTY yarn) having a total fineness of 84 dtex / 72 strands, a raschel lace was produced at 28G 40 cpi. The weave structure and fabric properties are shown in Table 3.

[0056] The fabric obtained was inferior to that obtained in Example 3. In particular, the image blocking ability was low, and the suppression of visibility of objects on the other side of the fabric was insufficient.

[0057]

[0058]

[0059]

[0060] [Example 4] Polyethylene terephthalate with an intrinsic viscosity of 0.65 dL / g and no matting agent in the polymer was used. After hot air drying at 160°C for 6 hours, the polymer was fed into a melt extruder to produce a 285°C molten polymer, which was then extruded from a spinneret equipped with 30 nozzles forming a modified cross section corresponding to the cross section shown in Figure 1. After extrusion, the polymer was cooled by horizontally blowing cold air at a temperature of 20°C and a relative humidity of 65% at a speed of 0.3 m / s from a position 120 mm below the spinneret. A 10% water emulsion finishing oil was then applied, and the resulting yarn was taken up at a spinning speed of 1000 m / min, yielding an undrawn yarn with a total fineness of 235 dtex / 30 fibers. The yarn was then drawn 2.8 times between a preheated roller at 85°C and a drawing roller at 130°C, yielding a yarn (A) consisting of 30 modified flat cross section fibers with inclined surfaces and a total fineness of 83 dtex / 30 fibers. Each single fiber constituting the yarn was a non-uniform flat cross section fiber having seven straight portions of the same shape (as shown in FIG. 1).

[0061] Polyethylene terephthalate containing 0.3% by weight of titanium oxide as a delustering agent and having an intrinsic viscosity of 0.65 dL / g was spun and drawn in a conventional manner to obtain a polyester multifilament (B) with a round cross section and a total fineness of 84 dtex / 36 strands.

[0062] Next, using the multifilament (B) as the warp and two parallel multifilaments (A) as the weft, a plain weave fabric was woven with a warp density of 88 threads / 2.54 cm and a weft density of 67 threads / 2.54 cm. This was then dyed using a conventional method without using a dye to obtain a fabric with a warp density of 107 threads / 2.54 cm, a weft density of 75 threads / 2.54 cm, and a cover factor (CF) of 1845.

[0063] The resulting fabric had a heat shielding property of 38%, an ultraviolet shielding property of 93%, and a light transmission property of 15.39%, and was therefore excellent in heat shielding property, ultraviolet shielding property, and light transmission property. The evaluation results are shown in Table 4.

[0064] Example 5 A yarn and a woven fabric were obtained in the same manner as in Example 4, except that polyethylene terephthalate having an intrinsic viscosity of 0.65 dL / g and containing 0.3 wt % of titanium oxide having a particle size of 0.3 μm as a matting agent in the polymer was used.

[0065] The resulting woven fabric had a heat shielding property of 39%, an ultraviolet shielding property of 95%, and a light transmission property of 13.59%, indicating that the fabric was excellent in heat shielding property, ultraviolet shielding property, and light transmission property. The evaluation results are shown in Table 4.

[0066] [Example 6] A yarn was obtained in the same manner as in Example 4, except that the spinneret used in Example 4 was changed, the discharge holes were changed to have the cross-sectional shapes shown in Table 4, and the cross-sectional shapes were changed.

[0067] Next, using the multifilament (B) as the warp and two paralleled multifilaments (A) as the weft, a 3 / 1 twill fabric with a warp density of 127 threads / 2.54 cm and a weft density of 71 threads / 2.54 cm was woven. This was then dyed using a conventional method without using a dye to obtain a fabric with a warp density of 155 threads / 2.54 cm, a weft density of 80 threads / 2.54 cm, and a cover factor (CF) of 2322.

[0068] The resulting fabric had a heat shielding property of 40%, an ultraviolet shielding property of 95%, and a light transmission property of 12.53%, indicating that the fabric was excellent in heat shielding property, ultraviolet shielding property, and light transmission property. The evaluation results are shown in Table 4.

[0069] [Example 7] A woven fabric having a warp density of 108 threads / 2.54 cm, a weft density of 74 threads / 2.54 cm and a cover factor (CF) of 1842 was obtained in the same manner as in Example 4, except that 2.6% by weight of titanium oxide having a particle size of 0.3 μm was added to the yarn (A) as a matting agent.

[0070] The obtained woven fabric had a heat shielding property of 42%, an ultraviolet shielding property of 93%, and a light transmission property of 11.30%, and was therefore excellent in heat shielding property, ultraviolet shielding property, and light transmission property. The evaluation results are shown in Table 4.

[0071] Comparative Example 7 A woven fabric having a warp density of 108 threads / 2.54 cm, a weft density of 75 threads / 2.54 cm and a cover factor (CF) of 1854 was obtained in the same manner as in Example 5, except that the cross-sectional shape of the yarn (A) was changed to a four-peak flat type (a flat cross section having three constrictions and a cross-sectional flatness of 3.2) as described in Example 1 of JP 2024-14344 A.

[0072] The fabric obtained had a heat shielding property of 31%, an ultraviolet shielding property of 93%, and a light transmission property of 15.92%, which indicated that the fabric had poor ultraviolet and heat shielding property. The evaluation results are shown in Table 4.

[0073] Comparative Example 8 In Example 5, the cross section of the yarn (A) was changed to a round cross section, and a woven fabric having a warp density of 107 threads / 2.54 cm, a weft density of 76 threads / 2.54 cm, and a cover factor (CF) of 1857 was obtained in the same manner as in Example 4.

[0074] The fabric obtained had a heat shielding property of 28%, an ultraviolet shielding property of 67%, and a light transmission property of 14.32%, which means that the fabric was poor in both heat shielding property and ultraviolet shielding property. The evaluation results are shown in Table 4.

[0075]

[0076] According to the present invention, there are provided a modified flat cross section fiber, a fabric, and a textile product using said fabric, which are excellent in heat shielding properties, ultraviolet shielding properties, transparency prevention properties, and light transmission properties, and the industrial value of these is extremely great.

[0077] A: Maximum length of the cross section of the irregular flat fiber in the longitudinal direction B: Maximum width of the cross section of the irregular flat fiber in the lateral direction C: Distance between the incisions in the lateral direction in the cross section of the irregular flat fiber θs: Angle (inclination angle) between the longitudinal direction of the cross section and each linear portion in the cross section of the irregular flat fiber θ0: Incident angle of light to the interface between the polymer layer and the air layer θ1: Transmission angle of light when passing from the polymer layer to the air layer

Claims

1. An irregular flat cross section fiber, characterized in that in the cross section of the fiber, the number of linear portions having an inclination angle relative to the longitudinal direction of the cross section is within the range of 6 to 12, the flatness is within the range of 3 to 6, the irregularity is within the range of 2 to 4.5, and the inclination angle is within the range of 30° to 70°.

2. The irregular flat cross section fiber according to claim 1, wherein the content of the matting agent in the irregular flat cross section fiber is 3.0% by weight or less.

3. The modified flat cross section fiber according to claim 2, wherein the modified flat cross section fiber is made of polyester, polyamide, or polyethylene.

4. A fabric comprising the modified flat cross section fiber according to any one of claims 1 to 3, which is a woven fabric having a cover factor (CF) of 1500 to 3500, or a knitted fabric having 10 to 50 courses / 2.54 cm and 9 to 30 wales / 2.54 cm, where the cover factor (CF) is defined by the following formula: CF = (DWp / 1.1). １／２ ×MWp+(DWf / 1.1) １／２ × MWf [DWp is the total warp fineness (dtex), MWp is the warp weave density (counts / 2.54 cm), DWf is the total weft fineness (dtex), and MWf is the weft weave density (counts / 2.54 cm)] 5. The fabric according to claim 4, which has a heat shielding property of 35% or more as measured in accordance with JIS L1951.

6. The fabric according to claim 4, which has an ultraviolet ray shielding property of 90% or more as measured according to JIS L1925.

7. The fabric according to claim 4, which has a light transmission rate of 10% or more as measured in accordance with JIS L1913.

8. A textile product selected from the group consisting of curtains, tents, shoji paper, clothing, and hats, which is made using the fabric according to any one of claims 4 to 7.

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