Near-infrared shielding fiber, method for producing same, master batch for fiber, blended yarn, apparel article, and article of daily use

Abstract

The present invention provides a fiber which more effectively shields thermal energy and has improved thermal insulation properties. A near-infrared shielding fiber which has at least one continuous layer (A) in the longitudinal direction of the fiber, the continuous layer (A) being obtained by dispersing titanium oxide particles in a first fiber-forming resin, the volume fraction of the titanium oxide particles exhibiting a particle diameter of 0.40-1.25 [mu] m being 70% or more, and the volume fraction of the titanium oxide particles exhibiting a particle diameter of 0.40-1.25 [mu] m being 70% or more. The titanium oxide particles are contained in an amount of 3-18% by mass relative to the continuous layer (A).

Description

Technical Field

[0001] The present invention relates to near infrared shielding fiber and a manufacturing method thereof, a fiber masterbatch, blended yarn, clothing items and daily necessities. Background Art

[0002] In the past, various types of fibers have been proposed as fibers that can provide a cooling feeling when used in fabrics, such as fibers that can be used in clothing that provides a cooling feeling by reflecting strong sunlight, and fibers that can be used in curtains to mitigate increases in indoor temperature.

[0003] For example, Patent Document 1 discloses that by producing a core-sheath type composite fiber in which the core portion contains 3% by weight or more of titanium oxide having an average particle size of 0.8 to 1.8 μm and the sheath portion contains substantially no titanium oxide having an average particle size of 0.8 μm or more, a product having a cool feeling can be obtained at low cost without performing a bulking treatment or silver plating.

[0004] Patent document 2 discloses the following: By preparing a core-sheath type composite fiber in which the core component is a polyester polymer containing 8 wt% to 70 wt% of titanium oxide with an average particle size of 0.2 to 0.8 μm and the surface is coated with an aluminum oxide compound, and the sheath component is a polyester polymer containing 0.5 wt% to 4.0 wt% of inorganic fine particles, and the weight ratio of the core component to the sheath component is 10:90 to 40:60, a polyester core-sheath type composite fiber having excellent anti-permeability, heat insulation, color rendering and light resistance and a method for manufacturing the same can be provided.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-116660

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2019-7096 Summary of the Invention

[0009] Patent Document 1 is characterized by the use of titanium oxide of a specific particle size to reflect light with a wavelength of 0.8 to 3 μm, which is easily converted into heat energy. Patent Document 2 is also characterized by the inclusion of a large amount of specific titanium oxide in the core to achieve high reflectivity at visible and infrared wavelengths (380 to 3000 nm). However, due to the recent impact of climate change, there is a demand for fibers with more effective thermal insulation properties.

[0010] Therefore, an object of the present invention is to obtain a fiber that can shield heat energy more effectively and improve thermal insulation properties.

[0011] The present inventors conducted intensive research and discovered that, in order to effectively scatter and shield near-infrared light with a wavelength of 800 to 2500 nm, they focused on shielding the energy of this wavelength by utilizing diffusion based on Mie scattering. By using titanium oxide with a specific particle size distribution of approximately half the size of the aforementioned wavelength, it is possible to effectively shield light with wavelengths in the near-infrared region, thereby completing the present invention.

[0012] That is, the present invention is as follows:

[0013] The first embodiment is a near-infrared shielding fiber having at least one continuous layer A in the longitudinal direction of the fiber.

[0014] The continuous layer A is formed by dispersing titanium oxide particles in a first fiber-forming resin.

[0015] The volume percentage of the titanium oxide particles having a particle size of 0.40 to 1.25 μm is 70% or more.

[0016] The titanium oxide particles are contained in an amount of 3 to 18% by mass relative to the continuous layer A.

[0017] A second embodiment is a sea-island type composite fiber in which the near-infrared shielding fiber is a sea-island type composite fiber, the island portion is the continuous layer A, and the sea portion is a second fiber-forming resin layer containing a component that scatters visible light and ultraviolet rays.

[0018] A third embodiment is a near-infrared shielding fiber that is a sea-island type composite fiber, wherein the island portion is the continuous layer A and the sea portion is a portion composed of a readily soluble component.

[0019] Furthermore, a fourth aspect is that in the near-infrared shielding fiber, the area ratio of the sea portion:the island portion in the fiber cross section is 50:50 to 5:95.

[0020] A fifth embodiment is a fiber masterbatch comprising 30 to 60 mass % of titanium oxide particles dispersed in a fiber-forming resin, wherein the titanium oxide particles having a particle size of 0.40 to 1.25 μm account for 70% or more of the volume fraction thereof.

[0021] In addition, the sixth option is a method for manufacturing the above-mentioned near-infrared shielding fiber, comprising: a process of diluting the above-mentioned masterbatch with the same type of fiber-forming resin used in the above-mentioned masterbatch, and a process of melt-spinning the diluted masterbatch to obtain a fiber having at least one continuous layer A in the axial direction of the fiber.

[0022] Furthermore, the seventh embodiment is an article of clothing using the above-mentioned near-infrared shielding fiber, and the eighth embodiment is a daily necessities product using the above-mentioned near-infrared shielding fiber.

[0023] Furthermore, the ninth embodiment is a near-infrared shielding blended yarn obtained by blending the above-mentioned near-infrared shielding fiber as a short fiber with cotton and / or water-absorbent quick-drying short fiber.

[0024] The tenth embodiment is an article of clothing using the above-mentioned near-infrared shielding blended yarn.

[0025] The fiber of the present invention can effectively shield light (heat energy) with wavelengths in the near-infrared region (typically 800 to 2500 nm) in sunlight, and thus can effectively diffuse thermal radiation of this wavelength. If used as a fabric, it can suppress the temperature rise caused by sunlight.

[0026] In particular, when used in daily necessities such as curtains, it can suppress the rise in room temperature caused by sunlight. Furthermore, when used in clothing items such as polo shirts and hats, it can alleviate the body's sense of heat caused by sunlight.

[0027] According to the masterbatch of the present invention, by using the same fiber-forming resin as that used in the masterbatch as a diluent resin for melt spinning, stable spinning can be performed, and fibers having improved thermal insulation properties can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a graph showing the particle size distribution of titanium oxide used in Example 1 and Comparative Examples 5 and 6.

[0029] Figure 2 : is the particle size distribution of the control yarn and the titanium oxide used in Comparative Example 1.

[0030] Figure 3 This is the particle size distribution of titanium oxide used in Comparative Example 2.

[0031] Figure 4 This is the particle size distribution of titanium oxide used in Comparative Example 3.

[0032] Figure 5 This is a graph showing the particle size distribution of titanium oxide used in Examples 7 and 8.

[0033] Figure 6 It is a reference diagram showing a method for evaluating thermal insulation performance. DETAILED DESCRIPTION

[0034] The present invention is a near-infrared shielding fiber containing titanium oxide.

[0035] The near-infrared shielding fiber of the present invention has at least one continuous layer A in the fiber major axis direction.

[0036] The continuous layer A is formed by dispersing titanium oxide particles in a fiber-forming resin, and the ratio of titanium oxide in the continuous layer A is 3 to 18% by mass.

[0037] The titanium oxide particles must have a particle size of 0.40 to 1.25 μm (400 to 1250 nm) and must exist in an amount of 70% or more by volume.

[0038] The above-mentioned existence volume percentage can be calculated by the following formula.

[0039] [Existing volume percentage of particles with a particle size of 0.40 to 1.25 μm (%)] = [Cumulative value of particles with a particle size of 1.25 μm (%)] - [Cumulative value of particles with a particle size of 0.40 μm (%)]

[0040] A method for measuring the volume percentage of titanium oxide present in the above-mentioned particle size range of 0.40 to 1.25 μm (400 to 1250 nm) will be described.

[0041] For the volume percentage of titanium oxide present, the laser diffraction particle size distribution determination method generally used in the particle size distribution determination of powders is applied to measure the particle size, frequency, and accumulation. At this time, it is important to fully disperse the particles to be measured in water as the measurement medium. When preparing the dispersion liquid for measurement, the dispersion liquid must be irradiated with ultrasound for at least 5 minutes, preferably more than 10 minutes. In addition, a surfactant can be added for the purpose of facilitating dispersion or stabilizing dispersion. Specifically, the measurement can be performed as described in the examples described below. In addition, as long as the same measured value can be obtained, the measuring instrument can be changed.

[0042] Generally, the product commercially available as a general-purpose titanium oxide used in fibers is anatase-type titanium oxide, which is generally called a matting agent and diffuses the wavelength of the visible light region (typically 380 to 800 nm) to appear white and suppress the gloss. The following describes the method for producing such a general titanium oxide. Generally, the mainstream method is the sulfuric acid method. First, ilmenite, which is a raw material ore, is crushed and treated with concentrated sulfuric acid to obtain titanium sulfate. The obtained titanium sulfate is hydrolyzed to produce hydrated titanium hydroxide. Furthermore, the hydrated titanium hydroxide is calcined using a rotary kiln or the like. Then, it is crushed and classified to obtain titanium oxide. In this method, the maximum diameter is about 1 μm, and the median particle size (the volume frequency of the particle size is accumulated to 50%, also called D 50 The particle size is about 0.2 to 0.4 μm.

[0043] In contrast, since the volume fraction of the titanium oxide particles used in the present invention showing a particle size of 0.40 to 1.25 μm is 70% or more, it is necessary to increase the particle size. As a general method for producing large-particle titanium oxide, when the temperature and time during calcination of hydrated titanium hydroxide are increased, the grain growth of the titanium oxide crystals in one direction can be increased, resulting in a large particle size. However, since the shape of the titanium oxide particles is rod-shaped, the scattering efficiency is reduced. In this case, the ratio of the major diameter to the minor diameter of the titanium oxide particles is about 4 to 10, which is relatively large. It should be noted that the ratio of the major diameter to the minor diameter of the titanium oxide particles can be measured and calculated using transmission electron microscope photographs or scanning electron microscope photographs taken at appropriate magnifications during particle size distribution measurement.

[0044] The titanium oxide particles used in the present invention are preferably those produced by the production method disclosed in International Publication No. WO2004 / 052786. Specifically, to increase the particle size while preventing unidirectional crystal growth, 0.1-0.5% by weight of an aluminum compound (calculated as Al2O3), 0.2-1.0% by weight of a zinc compound (calculated as ZnO), and 0.1-0.5% by weight of a potassium compound (calculated as K2CO3) are mixed with hydrated titanium hydroxide, based on the TiO2 content. The resulting mixture is calcined at 900-1100°C to induce grain growth. This produces titanium oxide particles with a major-to-minor-diameter ratio of approximately 1-3, which is less likely to reduce scattering efficiency and a large particle size.

[0045] As the titanium oxide used in the present invention, for example, titanium oxide grown by the above-mentioned method is classified so that the volume fraction of titanium oxide particles having a particle size of 0.40 to 1.25 μm (400 to 1250 nm) is 70% or more.

[0046] In the above-mentioned production method, since the crystal grains are grown at a high temperature, the crystal form is rutile.

[0047] The classification method may be air classification or classification by elutriation, and air classification is preferred in order to avoid secondary aggregation during drying.

[0048] Next, the fiber-forming resin will be described.

[0049] The fiber-forming resin is not particularly limited as long as it is a melt-spinnable thermoplastic resin. However, considering the use in clothing fabrics, daily necessities, etc., it is preferably selected from polyester resins, polyamide resins, and polyolefin resins.

[0050] The polyester resin is obtained by dehydration polycondensation of an acid component and a diol component. Examples thereof include polyethylene terephthalate obtained by reacting terephthalic acid with ethylene glycol, polypropylene terephthalate obtained by reacting terephthalic acid with propylene glycol, polybutylene terephthalate obtained by reacting terephthalic acid with 1,4-butanediol, and polyethylene furandicarboxylate obtained by reacting furandicarboxylic acid with ethylene glycol.

[0051] These polymers may be used as homopolymers or as copolyester resins obtained by replacing part of the acid component with isophthalic acid, naphthalene dicarboxylic acid, cyclohexanedimethanol, etc., and part of the diol component with diethylene glycol, polyethylene glycol, etc., within a range that does not degrade the properties.

[0052] Examples of the polyamide resin include polyamide 6, polyamide 4, and polyamide 12 obtained by ring-opening polymerization of cyclic lactams, polyamide 11 obtained by condensing aminocarboxylic acids such as 11-aminoundecanoic acid, and polyamide 66, polyamide 610, and polyamide 1010 obtained by dehydration condensation of diamine compounds and dicarboxylic acid compounds.

[0053] Some of these polymers may be copolymerized.

[0054] As the polyolefin resin, high-density polyethylene resin, polypropylene resin, polymethylpentene resin, etc. can be appropriately used.

[0055] Furthermore, the fiber-forming resin may be compounded with a heat-resistant agent, an antioxidant, carbon black, a pigment such as iron oxide (Bengala), etc., within a range that does not degrade the physical properties and heat insulation properties of the fiber.

[0056] The first fiber-forming resin used in the continuous layer A is one or a combination of two or more of the above-mentioned fiber-forming resins. The content of the titanium oxide particles in the first fiber-forming resin used in the continuous layer A should be 3 to 18% by mass. A content of less than 3% results in a low near-infrared shielding effect, while a content exceeding 18% by mass tends to reduce fluidity and cause breakage during stretching. A more preferred content of the titanium oxide particles in the fiber-forming resin used in the continuous layer A is 6 to 12% by mass.

[0057] As described above, the near-infrared shielding fiber of the present invention has, in the fiber longitudinal direction, at least one continuous layer A. The continuous layer A is formed by dispersing the titanium oxide particles in the fiber-forming resin.

[0058] The near-infrared shielding fiber of the present invention may be a single fiber having only one continuous layer A in the longitudinal direction of the fiber, or may be a composite fiber having one or more continuous layers A.

[0059] When the near-infrared shielding fiber is a composite fiber, the cross-sectional shape of the composite fiber is not particularly limited. Suitable cross-sectional shapes of the composite fiber include, for example, sea-island composite fibers having one or more continuous layers A in the island portion and a conventional fiber-forming resin layer that does not contain the titanium oxide particles in the sea portion.

[0060] When the near-infrared shielding fiber is a sea-island type composite fiber, the continuous layer A of the near-infrared shielding fiber of the present invention preferably contains 50% or more, more preferably 66% or more of the area ratio of the fiber cross section in order to obtain excellent heat shielding properties.

[0061] From the perspective of fiber cross-sectional formability, the upper limit of the area ratio of the continuous layer A in the fiber cross section is preferably 95%, more preferably 90%. If the area ratio of the continuous layer A in the fiber cross section exceeds 95%, there is a possibility that the seam portion will not be continuously and stably connected.

[0062] That is, the area ratio of the sea portion:the island portion in the fiber cross section is preferably 50:50 to 5:95, more preferably 50:50 to 10:90, and even more preferably 34:66 to 10:90.

[0063] When the near-infrared shielding fiber of the present invention is a sea-island type composite fiber, it is preferably made into a fiber cross-sectional shape in which the island portion is a continuous layer A and the sea portion has a fiber-forming resin layer that does not contain the above-mentioned titanium oxide particles from the aspects of heat insulation, process passability, and cloth-making properties.

[0064] When the continuous layer A is used in the island portion, the sea component used in the fiber-forming resin layer of the sea portion preferably contains a component that scatters visible light and ultraviolet light. Preferred specific examples include white pigments with an average particle size of 0.2 to 0.5 μm. Examples of white pigments include titanium oxide, zinc oxide, barium sulfate, and calcium carbonate. Among these, titanium oxide is preferred, and anatase-type titanium oxide is particularly preferred.

[0065] These white pigments, such as titanium oxide, are preferably present in an amount of approximately 0.3 to 1.5% by mass relative to the fiber-forming resin. The fiber-forming resin (second fiber-forming resin) used in the sea portion may be one or a combination of two or more of the aforementioned fiber-forming resins. Furthermore, the first fiber-forming resin (the fiber-forming resin used in the continuous layer A) and the second fiber-forming resin may be the same or different.

[0066] The white pigment is contained not only in the sea component of the sea portion but also in the island component of the island portion.

[0067] Furthermore, the white pigment may be contained in the continuous layer A or the fiber-forming resin layer that does not contain the titanium oxide particles, even when the fibers are not island-in-the-sea composite fibers.

[0068] In the present invention, when the white pigment is contained, the volume percentage of particles having a particle size of 0.40 to 1.25 μm is 70% or more when the white pigment titanium oxide and the large-particle titanium oxide are combined.

[0069] When the near-infrared shielding fiber of the present invention is a sea-island composite fiber and the continuous layer A is used as the island portion, the sea component used in the fiber-forming resin layer of the sea portion can be a readily soluble component. In this case, for example, the sea component can be easily removed by subjecting a fabric woven from the sea-island composite fiber to an alkali weight reduction treatment or a hot water weight reduction treatment.

[0070] Suitable easily soluble components include easily alkali soluble components and hot water soluble components.

[0071] Preferred examples of the readily alkali-soluble component include an alkali-soluble polyester resin comprising 2.0 to 3.0 mol% of an isophthalic acid component containing a metal sulfonate group in a terephthalic acid-based acid component, 6 to 12% by mass of a polyalkylene glycol having an average molecular weight of 3,000 to 10,000 in the polymer, and a diethylene glycol content of 4.5 to 6.0 mol%.

[0072] Preferred examples of other readily soluble components include hot-water-soluble polyester resins composed primarily of terephthalic acid as an acid component and ethylene glycol as a diol component, wherein 8 to 15 mol% of the acid component is sodium sulfoisophthalate, 10 to 40 mol% of the acid component is isophthalic acid, and 8 to 25 mol% of the diol component is diethylene glycol. Furthermore, as the hot-water-soluble resin, there is no problem in using ethylene-vinyl alcohol copolymer resins obtained by further saponifying ethylene-vinyl acetate copolymer resins obtained by polymerizing ethylene and vinyl acetate.

[0073] When the near-infrared shielding fiber of the present invention is a single fiber consisting only of a continuous layer A, if a large amount of titanium oxide particles are dispersed, it is possible that the yarn guide, roller, net and other parts will be worn during the spinning and weaving processes. In this way, if the continuous layer A is used for the island part and the above-mentioned easily soluble component is used for the sea part, the easily soluble component can be easily removed in the subsequent process after spinning and weaving, which can prevent troubles from occurring in the various spinning and weaving processes.

[0074] When the near-infrared shielding fiber of the present invention is a single fiber consisting solely of the continuous layer A, particularly preferred uses include spunbond nonwoven fabrics or wadding. Spunbond nonwoven fabrics can be produced using a spinning device or nonwoven fabric manufacturing apparatus equipped with an air jet ejector. Wadding can be made of staple fibers (staple fibers) obtained by spinning single fibers consisting solely of the continuous layer A and then cutting them to a predetermined length without winding.

[0075] Furthermore, the near-infrared shielding fiber of the present invention can be cut into staple fibers to a predetermined length and then blended with staple fibers composed of cotton and / or water-absorbent, quick-drying fibers (e.g., fibers having a Y-shaped or C-shaped cross-section) to form a blended yarn. It should be noted that the fibers are more preferably crimped using a method such as the Oshikomi method before being cut into predetermined lengths to form a blended yarn.

[0076] When the near-infrared shielding fiber of the present invention is a sea-island composite fiber, the area ratio of the sea portion:island portion in the fiber cross section is preferably 50:50 to 5:95. It is more preferably 50:50 to 10:90, and even more preferably 34:66 to 10:90. Within this range, the island portions are not exposed on the fiber surface, allowing for stable spinning.

[0077] Hereinafter, an example of a method for producing the near-infrared shielding fiber of the present invention will be described.

[0078] First, titanium oxide particles having a particle size of 0.40 to 1.25 μm (400 to 1250 nm) are prepared, with a volume fraction of 70% or more. A predetermined amount of these titanium oxide particles is dispersed in a fiber-forming resin using a biaxial extruder or other extruder to produce fiber-forming resin pellets. These pellets are placed in the hopper of a spinning machine, melt-spun through a spinneret capable of forming a continuous layer A in the longitudinal direction of the fiber, and then appropriately stretched to produce the near-infrared shielding fiber of the present invention.

[0079] As in the above-mentioned method, particles in which 3 to 18% by mass of titanium oxide particles are dispersed by melt kneading can be used to form the continuous layer A. Furthermore, from the perspectives of cost and stable spinning, it is preferred to form a masterbatch of titanium oxide particles in a fiber-forming resin to minimize aggregation of the titanium oxide particles and allow for more uniform dispersion. The masterbatch is then diluted with the fiber-forming resin before melt spinning.

[0080] When the masterbatch is formed, for example, the target masterbatch can be appropriately obtained by setting a resin feeding area, a melting area (first kneading area), a titanium oxide feeding area (side feeding area), and a spike mixing area (or a mixing area using a notched seal or a mixing area using progressive thin blade kneading) in a co-rotating meshing twin-screw extruder for kneading. As the second kneading area, it is preferred to use a screw in which a mixing area using thin blades (thickness less than 1 / 7 of the screw diameter) for kneading is arranged in the above order. The key is to feed the fiber-forming resin from the most upstream part, and when it is completely melted, use a side feeder to feed titanium oxide in a prescribed proportion in the range of 30 to 60% by mass relative to the fiber-forming resin, and disperse it in the spike mixing area to avoid aggregation. The set temperature and screw speed during kneading can be appropriately adjusted while confirming the torque load of the motor and the discharge condition. It should be noted that if at least one screw with a notch with forward twist and reverse twist is provided after the spike mixing area, the dispersion is further improved, and thus it is preferred.

[0081] When using the above masterbatch to form the continuous layer A, it is crucial that the fiber-forming resin constituting the masterbatch and the diluent resin be the same type. If the fiber-forming resin constituting the masterbatch and the diluent resin are different types of fiber-forming resin, the spinning nozzle may produce a rain-like or dog-leg shape during spinning, and the die hole may become larger, making it difficult to achieve continuous and stable spinning.

[0082] Example

[0083] The present invention will be described in detail below with reference to Examples. However, the present invention is not limited to the following Examples.

[0084] The methods for measuring and evaluating various physical properties are as follows.

[0085] [Showing the volume percentage of particles with a diameter of 0.40 to 1.25 μm: Particle size distribution measurement method and specific particle size abundance ratio]

[0086] The particle size distribution was measured using a particle size distribution measuring apparatus MT3300EXII (manufactured by Microtrac BEL). Ion-exchanged water was used as the dispersion medium. The ion-exchanged water in which the titanium oxide particles were dispersed was irradiated with ultrasonic waves for 10 minutes to disperse the particles, and then the measurement was performed.

[0087] The volume fraction of particles having a volume particle diameter of 0.40 to 1.25 μm was calculated by the following formula.

[0088] [Existing volume percentage (%) of particles having a particle size of 0.40 to 1.25 μm] = [Cumulative value (%) of particles having a particle size of 1.25 μm] - [Cumulative value (%) of particles having a particle size of 0.40 μm].

[0089] 〔Measurement of long diameter and short diameter〕

[0090] The major axis and minor axis of the titanium oxide particles were measured based on photographs taken with a transmission electron microscope.

[0091] 〔Calculation method of ash content〕

[0092] Dry the sample (filament). Prepare a 2-5g sample in the form of a twisted wire. Place the sample in a porcelain crucible with an upper diameter of 50-60mm and a height approximately equal to the diameter. Accurately weigh the sample to determine the sample mass. Ash the sample in a muffle furnace at 600°C. Measure the residual ash mass. Calculate the ash content using the following formula.

[0093] Ash content (%) = (ash mass / sample amount) × 100

[0094] [Thermal insulation evaluation]

[0095] 1. Preparation of evaluation sample fabric

[0096] Evaluation sample fabrics were prepared by weaving a plain weave with a warp density of 110 yarns / 2.54 cm and a weft density of 77 yarns / 2.54 cm using conventional semi-dull polyester yarns 56 dtex / 24f as the warp and a parallel yarn obtained by plying two of the obtained polyester yarns as the weft.

[0097] 2. Preparation of control sample fabric

[0098] A control sample fabric was woven in the same manner as the evaluation sample fabric except that two conventional semi-dull polyester yarns of 84 dtex / 24f were twisted as a control yarn as the weft yarn.

[0099] 3. Preparation of Thermal Insulation Evaluation Test Fabric (Evaluation Sample Fabric, Control Sample Fabric)

[0100] The resulting evaluation sample fabric and control sample fabric were scoured with an aqueous solution of 2 g / L sodium bicarbonate (Fujifilm Wako Pure Chemical Industries, Ltd.) and 2 g / L polyoxyethylene alkyl ether (Kao Corporation) at 70°C for 20 minutes, and then heat-set at 180°C. The resulting fabric was cut into 10 cm squares to prepare thermal insulation evaluation test fabrics (evaluation sample fabric and control sample fabric).

[0101] 4. Preparation of evaluation samples and control samples, and preparation of thermal insulation measurement equipment

[0102] Reference Figure 6 The device shown is described.

[0103] Two evaluation sample fabrics were stacked so that the near infrared shielding fibers were perpendicular to each other to prepare an evaluation sample (1). Two control sample fabrics were stacked so that the near infrared shielding fibers were perpendicular to each other to prepare a control sample (2).

[0104] Prepare two sheets of black paper with temperature sensors attached.

[0105] The evaluation sample (1) and the control sample (2) are placed on black paper (5) to which the temperature sensor 1 (6) and the temperature sensor 2 (7) are attached, respectively.

[0106] The evaluation sample (1) and the control sample (2) were placed side by side, and a 500 W halogen lamp (3) (manufactured by Ushio Electric Co., Ltd.) was placed 50 cm vertically above the two samples.

[0107] An infrared transmission filter (800 to 2700 nm transmission type) manufactured by HOYA was installed between the evaluation sample (1) and the control sample (2) and the halogen lamp (3), and 2 cm above each sample as a near infrared transmission filter (4).

[0108] This filter shields long-wavelength light exceeding 2700 nm, which is hardly contained in sunlight.

[0109] 5. Evaluation of thermal insulation

[0110] The evaluation samples and control samples were illuminated with light from a 500W halogen lamp. After 30 minutes, the temperatures of the evaluation samples and control samples were checked with a temperature sensor. The [Evaluation Sample Temperature] - [Control Sample Temperature] was calculated and evaluated as follows.

[0111] ○: Temperature difference exceeds 2°C

[0112] ×: Temperature difference is 2°C or less

[0113] 〔Evaluation of Spinning Properties〕

[0114] Spinning was performed for 2 hours, and the spinnability was evaluated as follows.

[0115] ○: No problem

[0116] ×: There is an undesirable situation

[0117] 〔Control Silk Production〕

[0118] 0.4 mass% of Figure 2Polyethylene terephthalate resin particles containing anatase-type titanium oxide having the particle size distribution shown (average particle size (D50): 0.37 μm, showing a volume percentage of particles with a particle size of 0.40 to 1.25 μm: 43%) were used to produce 84 dtex / 24f drawn yarns as control yarns using a trial spinning machine under the same conditions as in Example 1 described later.

[0119] [Example 1]

[0120] 40% by mass of the Figure 1 Polyethylene terephthalate resin pellets of rutile titanium oxide having the particle size distribution shown (average particle size (D50): 1.0 μm, volume fraction of particles with a particle size of 0.40 to 1.25 μm: 75%) were compounded using a twin-screw extruder to prepare a masterbatch A (hereinafter sometimes referred to as MB-A).

[0121] Masterbatch A and polyethylene terephthalate resin pellets (fiber-forming resin) as a matrix were mixed at a ratio of 1:9. Using a prototype spinning machine, the spinning temperature was 290°C, the spinning speed was 1000 m / min, and the take-up speed was 3630 m / min to produce a drawn yarn of 84 dtex / 24 f. The resulting drawn yarn was a single fiber having a continuous layer (continuous layer A) in the longitudinal direction of the fiber. The ash content of the resulting drawn yarn was 4.0% by mass.

[0122] The thermal insulation evaluation of the obtained fiber showed that the temperature difference was -3°C, indicating that good thermal insulation was obtained.

[0123] [Example 2]

[0124] A drawn yarn of 84 dtex / 24 f was produced in the same manner as in Example 1 except that the masterbatch A and the matrix polyethylene terephthalate resin pellets (fiber-forming resin) were mixed at a ratio of 1:3.44. The ash content of the obtained drawn yarn was 9.0 mass %.

[0125] The thermal insulation evaluation of the obtained fiber showed a temperature difference of -5°C, indicating excellent thermal insulation.

[0126] [Example 3]

[0127] A drawn yarn of 84 dtex / 24 f was produced in the same manner as in Example 1 except that the masterbatch A and the matrix polyethylene terephthalate resin pellets (fiber-forming resin) were mixed at a ratio of 1:2.33. The ash content of the obtained drawn yarn was 12.0 mass %.

[0128] The thermal insulation evaluation of the obtained fiber showed a temperature difference of -6°C, indicating that very excellent thermal insulation was obtained.

[0129] [Comparative Example 1]

[0130] 40% by mass of the Figure 2 Anatase-type titanium oxide having the particle size distribution shown (average particle size (D50): 0.37 μm, abundance ratio of particles having a volume particle size of 0.40 to 1.25 μm: 43%) and polyethylene terephthalate resin pellets were compounded using a twin-screw extruder to prepare a masterbatch B (hereinafter sometimes referred to as MB-B).

[0131] A drawn yarn of 84 dtex / 24 f was produced in the same manner as in Example 1 except that the masterbatch B and the matrix polyethylene terephthalate resin pellets (fiber-forming resin) were mixed at a ratio of 1:3.44. The ash content of the obtained drawn yarn was 9.0 mass %.

[0132] The thermal insulation evaluation of the obtained fiber showed that the temperature difference was -1°C, indicating that sufficient thermal insulation was not obtained.

[0133] [Comparative Example 2]

[0134] 40% by mass of the Figure 3 Polyethylene terephthalate resin pellets of rutile titanium oxide having the particle size distribution shown (average particle size (D50): 0.82 μm, volume fraction of particles with a particle size of 0.40 to 1.25 μm: 58%) were compounded using a twin-screw extruder to produce a masterbatch C (hereinafter sometimes referred to as MB-C).

[0135] A drawn yarn of 84 dtex / 24 f was produced in the same manner as in Example 1 except that the masterbatch C and the matrix polyethylene terephthalate resin pellets (fiber-forming resin) were mixed at a ratio of 1:3.44. The ash content of the obtained drawn yarn was 9.0 mass %.

[0136] The thermal insulation evaluation of the obtained fiber showed that the temperature difference was -2°C, indicating that sufficient thermal insulation was not obtained.

[0137] The average particle size of the rutile titanium oxide used in this comparative example was between 0.40 and 1.25 μm, which is suitable for near-infrared reflection. However, due to the presence of a large amount of titanium oxide particles smaller than 0.04 μm, which do not contribute to near-infrared scattering, and particles larger than 1.25 μm, which do not effectively contribute to near-infrared reflection, it is believed that sufficient thermal insulation properties were not achieved.

[0138] [Comparative Example 3]

[0139] 40% by mass of the Figure 4Polyethylene terephthalate resin particles of rutile titanium oxide with the particle size distribution shown (average particle size (D50): 1.50 μm, volume percentage of particles with a particle size of 0.40 to 1.25 μm: 33%, aspect ratio: 6) are compounded using a twin-screw extruder to form a masterbatch D (hereinafter sometimes referred to as MB-D).

[0140] Spinning was performed using an 84 dtex / 24 f prototype spinning machine in the same manner as in Example 1, except that masterbatch D and polyethylene terephthalate resin pellets (fiber-forming resin) as the matrix were mixed at a ratio of 1:3.44. Significant unevenness in the single yarn fineness was observed. A very small amount of drawn yarn was collected and spinning was terminated immediately. The resulting drawn yarn had an ash content of 9.0 mass%.

[0141] [Comparative Example 4]

[0142] The masterbatch A of Example 1 and polyamide 6 resin (fiber-forming resin) pellets as a diluent resin were mixed in a ratio of 1 to 2.33 and intended for spinning. However, the discharge state from the spinning nozzle became a large dog-leg shape, resulting in large expansion and unable to be placed on the yarn path.

[0143] [Example 4]

[0144] The masterbatch A used in Example 1 and the polyethylene terephthalate (fiber-forming resin) resin particles as the matrix are mixed in a ratio of 1 to 3.44 as the island component, and the polyethylene terephthalate resin particles containing 0.4% by mass of titanium oxide used in the control yarn are used as the sea component. The respective resins are melted at 290°C, and a composite spinning machine is used with an island-in-the-sea spinneret (1 island, equivalent to a core-sheath spinneret) at a spinning speed of 1000m / min, a winding speed of 3600m / min, and the gear pump is adjusted so that the sea:island ratio is 10:90 to produce an island-in-the-sea type composite stretched yarn of 84dtex / 24f.

[0145] The thermal insulation evaluation of the obtained fiber showed a temperature difference of -4°C, indicating excellent thermal insulation.

[0146] [Example 5]

[0147] The masterbatch A of Example 1 and polyethylene terephthalate (fiber-forming resin) resin particles as a matrix are mixed in a ratio of 1 to 3.44 as the island component, and alkali-soluble polyester resin particles are used as the sea component. A trial spinning machine is used to produce 84dtex / 24f sea-island type composite stretched yarn with a sea:island ratio of 20:80.

[0148] In the thermal insulation evaluation, the evaluation sample fabric was obtained by completely dissolving and removing the sea component using a 4% by mass sodium hydroxide aqueous solution at 70° C. during scouring of the sample fabric.

[0149] The thermal insulation evaluation of the obtained fiber showed a temperature difference of -4°C, indicating excellent thermal insulation.

[0150] [Example 6]

[0151] The masterbatch A of Example 1 and polyethylene terephthalate (fiber-forming resin) resin particles as a matrix are mixed in a ratio of 1 to 3.44 as the island component, and a hot water-soluble polyester resin is used as the sea component. A trial spinning machine is used to produce an island-in-sea type composite stretched yarn of 84dtex / 24f with an area ratio of the sea part to the island part of 20:80.

[0152] In the thermal insulation evaluation, the evaluation sample fabric was obtained by boiling the sample fabric during scouring to completely dissolve and remove the sea component.

[0153] The thermal insulation evaluation of the obtained fiber showed a temperature difference of -4°C, indicating excellent thermal insulation.

[0154] [Example 7]

[0155] 30% by mass of titanium oxide was dispersed in a twin-screw extruder. Figure 5 Masterbatch E was prepared by compounding rutile titanium oxide (average particle size (D50): 0.94 μm, with a volume fraction of 0.40-1.25 μm particles: 83%) with polyethylene terephthalate resin particles. Masterbatch E was diluted threefold with polyethylene terephthalate to form the island component and the sea component, respectively. The mixture was melted at 290°C and spun using an island-in-the-sea spinneret (one island, equivalent to a core-sheath spinneret) at a sea:island resin ratio of 20:80 using a gear pump at a spinning speed of 1000 m / min and a take-up speed of 3600 m / min to produce island-in-the-sea composite fibers. The resulting drawn yarn had an ash content of 10.0% by mass. Furthermore, the resulting fiber exhibited excellent thermal insulation properties when evaluated at a temperature differential of -5°C.

[0156] [Example 8]

[0157] Masterbatch E was diluted threefold with polyethylene terephthalate (PET) as the island component, and polyethylene terephthalate as the sea component. These were melted at 290°C and spun using a seven-island spinneret. The sea:island resin ratio was adjusted to 25:75 using a gear pump. The fibers were spun at a spinning speed of 1000 m / min and a take-up speed of 3600 m / min to produce island-in-the-sea composite fibers. The resulting drawn yarn had an ash content of 10.0% by mass. Furthermore, the resulting fiber exhibited excellent thermal insulation properties, with a temperature differential of -5°C.

[0158] [Comparative Example 5]

[0159] A drawn yarn of 84 dtex / 24 f was produced in the same manner as in Example 1 except that the masterbatch A and the matrix polyethylene terephthalate resin pellets (fiber-forming resin) were mixed at a ratio of 1:19. The ash content of the obtained drawn yarn was 2.0 mass %.

[0160] The thermal insulation evaluation of the obtained fiber showed that the temperature difference was -1°C, indicating that sufficient thermal insulation was not obtained.

[0161] [Comparative Example 6]

[0162] A drawn yarn of 84 dtex / 24 f was produced in the same manner as in Example 1 except that masterbatch A and polyethylene terephthalate resin pellets (fiber-forming resin) as a matrix were mixed at a ratio of 1:1. However, yarn breakage occurred frequently and no drawn yarn could be obtained. The ash content of the broken yarn was measured and found to be 20% by mass.

[0163] Table 1 shows the physical properties of titanium oxide in Examples and Comparative Examples, the resins used, and various evaluations.

[0164] The "temperature reached after 30 minutes" in the thermal insulation evaluation refers to the temperature reached by the control sample of the control yarn and the evaluation samples of the examples and comparative examples 30 minutes after irradiation with a 500W halogen lamp. "MB" stands for masterbatch, and "MB: dilution ratio" indicates the mixing ratio (mass ratio) of the masterbatch and the dilution resin.

[0165] [Table 1]

[0166]

[0167] Examples 1-8 had at least one continuous layer in the fiber axis direction, obtained by dispersing titanium oxide particles with a particle size of 0.40 to 1.25 μm at a volume percentage of 70% or more in the fiber-forming resin layer, resulting in excellent thermal insulation. Comparative Examples 1-2 had a relatively low volume percentage of 33% to 58%, and therefore failed to achieve sufficient thermal insulation. Comparative Example 3 used titanium oxide with a very large particle size, but the particle shape was considered poor, and spinning was impossible for this reason. Furthermore, in Comparative Example 4, due to the different types of resin used in the masterbatch and the diluent resin, doglegs were evident when ejected from the spinneret, making spinning impossible. Comparative Example 5 did not exhibit a significant thermal insulation effect due to the low amount of titanium oxide present. In Comparative Example 6, the excessive amount of titanium oxide caused the yarn to break, and no evaluation yarn could be obtained.

[0168] [Example 9]

[0169] The fibers obtained in Example 2 were crimped using a crimper and then cut into 38 mm lengths to obtain staple fibers. The obtained staple fibers were mixed with 38 mm staple fibers of "Soierion (registered trademark)," a water-absorbing and quick-drying fiber manufactured by KB Seiren Co., Ltd., at a mass ratio of 2:1. Subsequently, a cotton roll was obtained while mixing using a blending machine. The obtained cotton roll was combed and bundled to obtain cotton strips. The obtained cotton strips were further stretched and twisted using a spinning machine to obtain near-infrared shielding blended yarn. The obtained near-infrared shielding blended yarn was used in clothing, and as a result, excellent heat insulation properties were obtained.

[0170] Industrial applicability

[0171] The near-infrared shielding fiber of the present invention has excellent shielding properties against near-infrared rays contained in sunlight and can be used in various applications requiring heat-shielding properties and cooling properties, such as clothing and daily necessities.

[0172] Explanation of symbols

[0173] 1: Evaluation sample

[0174] 2: Control sample

[0175] 3: Halogen lamp

[0176] 4: Near infrared transmission filter

[0177] 5: Black paper

[0178] 6: Temperature sensor 1 (for evaluation sample)

[0179] 7: Temperature sensor 2 (for control sample)

Claims

1. A near-infrared shielding fiber having at least one continuous layer A in the direction of the fiber's long axis, The continuous layer A is formed by dispersing titanium oxide particles in a first fiber-forming resin. The volume percentage of the titanium oxide particles having a particle size of 0.40 to 1.25 μm is 70% or more. The titanium oxide particles are contained in an amount of 3 to 18% by mass relative to the continuous layer A.

2. The near-infrared shielding fiber according to claim 1, which is a sea-island type composite fiber. The island portion is the continuous layer A, The sea portion is a second fiber-forming resin layer containing a component that scatters visible light and ultraviolet rays.

3. The near-infrared shielding fiber according to claim 1, which is a sea-island type composite fiber. The island portion is the continuous layer A, The sea part is composed of easily soluble components.

4. The near-infrared shielding fiber according to claim 2 or 3, wherein The area ratio of the sea portion: the island portion in the fiber cross section is 50:50 to 5:

95.

5. A fiber masterbatch comprising 30 to 60% by mass of titanium oxide particles dispersed in a fiber-forming resin. The titanium oxide particles have a particle size of 0.40 to 1.25 μm and the volume percentage of the particles is 70% or more.

6. A method for producing the near-infrared shielding fiber according to any one of claims 1 to 4, comprising: a step of diluting the masterbatch according to claim 5 with the same type of fiber-forming resin as used in the masterbatch, and A step of melt-spinning the diluted masterbatch to obtain fibers having at least one continuous layer A in the fiber axis direction.

7. An article of clothing comprising the near-infrared shielding fiber according to any one of claims 1 to 4.

8. Daily necessities comprising the near-infrared shielding fiber according to any one of claims 1 to 4.

9. A near-infrared shielding blended yarn, which is obtained by blending the near-infrared shielding fiber according to any one of claims 1 to 4 as a short fiber with cotton and / or a water-absorbent quick-drying short fiber.

10. An article of clothing comprising the near-infrared shielding blended yarn according to claim 9.

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