Thread and method for manufacturing the same, and article and method for determining authenticity thereof

Abstract

To provide a thread capable of exhibiting a circular polarization separation function, which can be produced by a simple method.SOLUTION: A thread includes a thread substrate and a polarization separation layer formed on the surface of the thread substrate. The polarization separation layer contains a cured product of cholesteric liquid crystal composition.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a yarn, a method for manufacturing the same, an article including the yarn, and a method for determining the authenticity thereof.

Background Art

[0002] A cholesteric liquid crystal composition has a circular polarization separation function of selectively transmitting one of circularly polarized light having a clockwise rotation direction (i.e., right circularly polarized light) and circularly polarized light having a counterclockwise rotation direction (i.e., left circularly polarized light) and selectively reflecting the other. Using this circular polarization separation function, conventionally, decorative yarns have been proposed (Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventional yarns using a cholesteric liquid crystal composition have a special manufacturing method, and the manufacturing method tends to be complicated.

[0005] For example, Patent Document 1 describes a method of manufacturing an optical functional fiber by winding an optical functional element obtained by processing a cholesteric liquid crystal layer into an elongated shape around a fiber material as a core. However, in the method described in Patent Document 1, since the cholesteric liquid crystal layer is wound around the core after being manufactured, the number of steps increases. That is, the step of forming the cholesteric liquid crystal layer, the step of processing the cholesteric liquid crystal layer into an elongated shape to obtain an optical functional element, and the step of winding the optical functional element around the core are performed separately, so the number of steps increases. Further, usually, after winding, it is required to fix the cholesteric liquid crystal layer to the core using an adhesive such as a UV curable ink. The number of steps also increases due to the step of performing such fixation using an adhesive. Furthermore, in the method described in Patent Document 1, generally, in order to compensate for the low mechanical strength of the cholesteric liquid crystal layer during winding, a support layer is also wound around the core together with the cholesteric liquid crystal layer. However, the more the support layer is used, the more members are used in the manufacture of the optical functional fiber, so the complexity of the manufacturing process increases. Thus, the optical functional fiber described in Patent Document 1 could not be manufactured without a complicated manufacturing method.

[0006] The techniques described in Patent Documents 2 and 3 are also the same as the optical functional fiber described in Patent Document 1 in that they require a complicated manufacturing method, although the structure of the obtained yarn is different from that of the optical functional fiber described in Patent Document 1.

[0007] The present invention was devised in view of the above problems, and an object thereof is to provide a yarn capable of exhibiting a circular polarization separation function that can be manufactured by a simple method and a method for manufacturing the same; and an article including the yarn and a method for determining the authenticity thereof.

Means for Solving the Problems

[0008] The present inventor diligently studied to solve the above problems. As a result, the present inventor found that a yarn including a yarn base material and a polarization separation layer formed by a cured product of a cholesteric liquid crystal composition on the surface of the yarn base material can solve the above problems, and completed the present invention. That is, the present invention includes the following.

[0009] 〔1〕 A yarn base material and, a polarization separation layer formed on the surface of the yarn base material, wherein the polarization separation layer contains a cured product of a cholesteric liquid crystal composition, a yarn. 〔2〕 The yarn according to 〔1〕, wherein the yarn base material is a drawn yarn. 〔3〕 The yarn according to 〔1〕 or 〔2〕, wherein the yarn base material is a twisted yarn. 〔4〕 The yarn according to any one of 〔1〕 to 〔3〕, wherein the polarization separation layer is continuously formed in the longitudinal direction and the circumferential direction of the yarn base material. 〔5〕 The yarn according to any one of 〔1〕 to 〔4〕, wherein the diameter of the yarn base material is 500 μm or less. 〔6〕 The yarn according to any one of 〔1〕 to 〔5〕, wherein the yarn base material is colored. 〔7〕 The yarn according to any one of 〔1〕 to 〔6〕, wherein the polarization separation layer can reflect right-handed circularly polarized light and transmit left-handed circularly polarized light. 〔8〕 The yarn according to any one of 〔1〕 to 〔6〕, wherein the polarization separation layer can reflect left-handed circularly polarized light and transmit right-handed circularly polarized light. 〔9〕 A method for manufacturing a yarn, comprising the steps of preparing a yarn base material, forming a layer of a cholesteric liquid crystal composition on the surface of the yarn base material, orienting the cholesteric liquid crystal composition, and curing the cholesteric liquid crystal composition, in this order. 〔10〕 An article comprising the yarn according to any one of 〔1〕 to 〔8〕. 〔11〕 The article according to 〔10〕, comprising an article body and the yarn sewn to the article body. 〔12〕 The yarn is a yarn for right circularly polarized light reflection, having a polarization separation layer that can reflect right-handed circularly polarized light and transmit left-handed circularly polarized light, and A thread for left circular polarization reflection, comprising a polarization separation layer capable of reflecting left-handed circularly polarized light and transmitting right-handed circularly polarized light, and The article according to

[10] or

[11] , comprising . 〔13〕 A method for determining the authenticity of an article according to any one of 〔10〕 to 〔12〕, comprising: observing the article through a right circular polarizing plate to obtain a first observation image; observing the article through a left circular polarizing plate to obtain a second observation image; determining the authenticity of the article based on the first observation image and the second observation image. A method for determining the authenticity of an article, comprising the above steps.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a thread capable of exhibiting a circular polarization separation function, which can be manufactured by a simple method, and a method for manufacturing the same; and an article provided with the thread and a method for determining the authenticity thereof.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in detail with reference to embodiments and exemplifications. However, the present invention is not limited to the embodiments and exemplifications described below, and can be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and its equivalent scope.

[0013] In the following description, unless otherwise specified, the in-plane retardation Re of the layer is a value represented by Re = (nx - ny) × d. Here, nx represents the refractive index in the direction (in-plane direction) perpendicular to the thickness direction of the layer and giving the maximum refractive index. ny represents the refractive index in the in-plane direction and orthogonal to the direction of nx. nz represents the refractive index in the thickness direction. d represents the thickness of the layer. Unless otherwise specified, the measurement wavelength is 550 nm.

[0014] In the following description, "circular polarization" includes elliptical polarization as long as the effects of the present invention are not significantly impaired.

[0015] [1. Outline of the composite yarn] FIG. 1 is a side view schematically showing a yarn 100 according to an embodiment of the present invention with a part broken. As shown in FIG. 1, a yarn 100 according to an embodiment of the present invention includes a yarn base material 110 and a polarization separation layer 120 formed on a surface 110S of the yarn base material 110. In the following description, the yarn 100 including the yarn base material 110 and the polarization separation layer 120 may be referred to as a "composite yarn".

[0016] The polarization separation layer 120 includes a cured product of a cholesteric liquid crystal composition. Since the cured product of the cholesteric liquid crystal composition has a circular polarization separation function, the polarization separation layer 120 can have a circular polarization separation function. The "circular polarization separation function" represents a function of reflecting circular polarization in one of the clockwise and counterclockwise rotation directions and transmitting circular polarization in the opposite rotation direction. Therefore, in the wavelength range in which the polarization separation layer 120 can exhibit the circular polarization separation function, the polarization separation layer 120 can reflect circular polarization in one of the clockwise and counterclockwise rotation directions and transmit circular polarization in the opposite rotation direction. In the following description, the above wavelength range in which the circular polarization separation function can be exhibited may be referred to as the "selective reflection range". The reflectance of the polarization separation layer 120 with respect to non-polarized light in this selective reflection range is usually 35% to 50%, preferably 40% to 50%.

[0017] Since the polarization separation layer 120 has a circular polarization separation function in the selective reflection range, the composite yarn 100 including the polarization separation layer 120 can also exhibit the circular polarization separation function. Therefore, the composite yarn 100 can realize various display forms utilizing its circular polarization separation function.

[0018] For example, when the composite yarn 100 is illuminated with light including circularly polarized light that the polarization separation layer 120 can reflect, the polarization separation layer 120 can reflect the circularly polarized light in the selective reflection range. Thus, the composite yarn 100 can be visually recognized as a yarn presenting the color of the circularly polarized light in the selective reflection range. Also, for example, when the composite yarn 100 is illuminated with light not including circularly polarized light that the polarization separation layer 120 can reflect, no light reflection or weak reflection occurs in the polarization separation layer 120. Thus, the composite yarn 100 cannot be visually recognized or can be visually recognized as a yarn presenting a color other than the circularly polarized light in the selective reflection range.

[0019] Furthermore, for example, when the composite yarn 100 illuminated with light including circularly polarized light that the polarization separation layer 120 can reflect is observed through a circular polarizing plate that can transmit the circularly polarized light that the polarization separation layer 120 can reflect, the circularly polarized light reflected by the polarization separation layer 120 can pass through the circular polarizing plate. Thus, the composite yarn 100 can be visually recognized as a yarn presenting the color of the circularly polarized light in the selective reflection range. Also, for example, when the composite yarn 100 illuminated with light including circularly polarized light that the polarization separation layer 120 can reflect is observed through a circular polarizing plate that can block the circularly polarized light that the polarization separation layer 120 can reflect, the circularly polarized light reflected by the polarization separation layer 120 cannot pass through the circular polarizing plate. Thus, the composite yarn 100 cannot be visually recognized or can be visually recognized as a yarn presenting a color other than the circularly polarized light in the selective reflection range.

[0020] This composite yarn 100 can be manufactured by a simple manufacturing method including, in this order, forming a layer of a cholesteric liquid crystal composition on the surface 110S of the yarn base material 110, aligning the cholesteric liquid crystal composition, and curing the cholesteric liquid crystal composition. Therefore, the composite yarn 100 can be manufactured by a simple manufacturing method.

[0021] [2. Thread substrate] The thread substrate is a substrate having the shape of a thread, and a wide range of threads can be used. The thread substrate has a surface as an outer peripheral surface on the outer periphery of the thread substrate, and a polarization separation layer is formed on this surface. The thread substrate usually functions as a core material of a composite thread and can enhance the mechanical strength of the composite thread. Therefore, even if the polarization separation layer is thin or the mechanical strength is low, the cutting of the composite thread can be suppressed.

[0022] The thread substrate usually may contain one or two or more fibers. When the thread substrate contains two or more fibers, those fibers may be twisted. Twisted fibers are generally called "twisted threads". This twisted thread may include spun yarns obtained by twisting short fibers such as cotton yarns and filament yarns obtained by twisting long fibers such as silk yarns, and both spun yarns and filament yarns can be used as the thread substrate. Also, as the fiber, natural fibers such as cotton, hemp, silk, and wool may be used, or chemical fibers may be used. Chemical fibers may include regenerated fibers obtained by spinning natural materials such as cellulose, semi-synthetic fibers obtained by subjecting natural materials to chemical treatment and spinning, and synthetic fibers formed of synthetic resins, and any of them can be used as the thread substrate.

[0023] Among these, it is preferable to use a thread containing chemical fibers as the thread substrate. Since chemical fibers are generally manufactured by a method including extruding raw materials from a spinning nozzle, they may have a uniform shape in the length direction. Therefore, when manufacturing the composite thread, the uniformity in the length direction of the alignment state of the liquid crystalline compound contained in the cholesteric liquid crystal composition can be enhanced. Therefore, a composite thread with high quality uniformity can be easily manufactured.

[0024] Also, it is preferable to use drawn yarn as the yarn base material. Drawn yarn refers to yarn that has been subjected to a drawing process during the manufacturing process. Since drawn yarn usually contains polymer molecules oriented in the length direction by the drawing process, the surface can have a large orientation control force due to the action of the oriented polymer molecules. The "orientation control force" of the surface refers to the property of the surface that can orient liquid crystalline compounds in the cholesteric liquid crystal composition.

[0025] The above-mentioned drawn yarn is preferably formed of a synthetic resin. Since the drawn yarn formed of a synthetic resin can have a particularly high orientation control force on the surface of the drawn yarn, a polarization separation layer excellent in the uniformity of the orientation state of the cholesteric liquid crystal composition can be formed. Preferred synthetic resins include, for example, nylon and polyethylene.

[0026] Usually, since the drawn yarn formed of a synthetic resin contains polymer molecules oriented in the length direction, it has birefringence. At this time, the slow axis as the direction in which the refractive index of the drawn yarn is the largest can be parallel or perpendicular to the length direction of the drawn yarn. Therefore, by observing a certain yarn with a polarizing microscope and examining the direction of the slow axis, it can be confirmed that the yarn is a drawn yarn.

[0027] As the material of the yarn base material, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio.

[0028] The yarn base material may be transparent or non-transparent. Also, there is no limitation on the color of the non-transparent yarn base material, and it may be colorless such as white, or colored. The color of the colored yarn base material may be achromatic such as black and gray, or chromatic such as red, green, and blue. The color of the yarn base material can be appropriately selected according to the design required for the composite yarn. Therefore, the yarn base material may be dyed with an appropriate dye or pigment as required.

[0029] In particular, the color of the yarn base material is preferably a dark color. A dark color can be a color with a lightness and chroma of 2 or less in the JIS Z 8721 Munsell notation. When using a yarn base material presenting a dark color, the amount of light reflected by the yarn base material can be suppressed. Therefore, the visibility of the circularly polarized light reflected by the polarization separation layer can be relatively enhanced, and the clarity of the design by the polarization separation layer can be enhanced.

[0030] The diameter (thickness) of the yarn base material can be appropriately set according to the design of the composite yarn. To give a specific range, the diameter of the yarn base material is preferably 500 μm or less, more preferably 450 μm or less, and particularly preferably 400 μm or less. The lower limit is preferably 50 μm or more, more preferably 100 μm or more, and particularly preferably 150 μm or more from the viewpoint of enhancing the visibility of the composite yarn.

[0031] [3. Polarization separation layer] The polarization separation layer is a layer containing a cured product of a cholesteric liquid crystal composition formed on the surface of the yarn base material. The polarization separation layer may be formed directly on the surface of the yarn base material or indirectly via an arbitrary layer. The mode where the polarization separation layer is formed on the surface of the yarn base material is called "direct" when there is no other layer between the yarn base material and the polarization separation layer and the polarization separation layer is in contact with the surface of the yarn base material. Among them, from the viewpoint of promoting the alignment of the cholesteric liquid crystal composition by the alignment regulating force of the surface of the yarn base material, the polarization separation layer is preferably formed directly on the surface of the yarn base material.

[0032] The polarization separation layer is preferably formed so as to cover at least a part of the surface of the yarn base material, and more preferably formed so as to cover the entire surface of the yarn base material. Also, the polarization separation layer is preferably formed continuously in the longitudinal direction of the composite yarn. Therefore, the polarization separation layer is preferably formed without being interrupted by a member, gap or discontinuous surface other than the polarization separation layer in the longitudinal direction of the composite yarn. Furthermore, the polarization separation layer is preferably formed continuously in the circumferential direction of the composite yarn. Therefore, the polarization separation layer is preferably formed without interruption by a member, gap, or discontinuous surface other than the polarization separation layer in the circumferential direction of the composite yarn. Also, the polarization separation layer is preferably formed continuously in the radial direction of the composite yarn. Therefore, the polarization separation layer is preferably formed without interruption by a member, gap, or discontinuous surface other than the polarization separation layer in the radial direction of the composite yarn. When the composite yarn according to this embodiment has a polarization separation layer that is continuous in the length direction, circumferential direction, and radial direction in this way, it can be easily manufactured.

[0033] As described above, the polarization separation layer contains a cured product of a cholesteric liquid crystal composition. A cholesteric liquid crystal composition refers to a composition that can exhibit a liquid crystal phase (cholesteric liquid crystal phase) in which the liquid crystalline compounds have cholesteric regularity when the liquid crystalline compounds contained in the liquid crystal composition are oriented. Here, for the sake of convenience, the material referred to as "liquid crystal composition" includes not only a mixture of two or more substances but also a material composed of a single substance. Examples of such cholesteric liquid crystal compositions include those described in JP-A-2014-174471 and JP-A-2015-27743.

[0034] Since the molecules contained in the cured product of the cholesteric liquid crystal composition have cholesteric regularity, the cured product can exhibit a circular polarization separation function. Cholesteric regularity means that on a certain plane, the molecular axes are arranged in a certain direction, but on the next plane overlapping it, the direction of the molecular axes is shifted at a slight angle, and on the next plane, the angle is further shifted. That is, as it passes through the planes arranged overlappingly in sequence, the angle of the molecular axes in the plane is shifted (twisted). That is, when the molecules inside a certain layer have cholesteric regularity, the molecules are arranged so that the molecular axes are in a certain direction on a first plane inside the layer. On the next second plane inside the layer that overlaps the first plane, the direction of the molecular axes is shifted at a slight angle from the direction of the molecular axes on the first plane. On the next third plane that further overlaps the second plane, the direction of the molecular axes is shifted at a further angle from the direction of the molecular axes on the second plane. Thus, in the planes arranged overlappingly, the angle of the molecular axes in the plane is sequentially shifted (twisted). The structure in which the direction of the molecular axes is twisted in this way is usually a helical structure and is an optically chiral structure.

[0035] Normally, the reflection in the cured product of the cholesteric liquid crystal composition reflects circularly polarized light while maintaining its chirality.

[0036] The specific wavelength at which the cured product of a cholesteric liquid crystal composition exhibits a circular polarization separation function generally depends on the pitch of the helical structure in the cured product of the cholesteric liquid crystal composition. The pitch of the helical structure is the distance in the direction of the normal to the plane in which the direction of the molecular axis gradually shifts as it progresses in the plane in the helical structure and then returns to the original molecular axis direction. By changing the magnitude of the pitch of this helical structure, the wavelength at which the circular polarization separation function is exhibited can be changed. As a method for adjusting the pitch, for example, the method described in JP-A-2009-300662 can be used. Specific examples include methods of adjusting the type or amount of the chiral agent in the cholesteric liquid crystal composition. In particular, when the magnitude of the pitch of the helical structure continuously changes within the layer of the cured product of the cholesteric liquid crystal composition, a circular polarization separation function over a wide wavelength range can be obtained with a single layer.

[0037] Examples of the layer of the cured product of a cholesteric liquid crystal composition that can exhibit a circular polarization separation function over a wide wavelength range include (i) a layer of a cured product of a cholesteric liquid crystal composition in which the magnitude of the pitch of the helical structure is changed stepwise, and (ii) a layer of a cured product of a cholesteric liquid crystal composition in which the magnitude of the pitch of the helical structure is changed continuously.

[0038] (i) A layer of a cured product of a cholesteric liquid crystal composition in which the pitch of the helical structure is changed stepwise can be obtained, for example, by laminating layers of cured products of a plurality of cholesteric liquid crystal compositions having different pitches of the helical structure. Lamination can be carried out, for example, by sequentially forming another layer on top of a formed layer.

[0039] (ii) A layer of a cured product of a cholesteric liquid crystal composition in which the pitch size of the helical structure is continuously changed can be obtained, for example, by subjecting a layer of the liquid crystal composition to a broadbanding treatment including irradiation treatment and / or heating treatment with active energy rays one or more times and then curing the layer of the liquid crystal composition. The "active energy rays" may include light such as visible light, ultraviolet rays, and infrared rays, and any energy rays such as electron beams. According to the above-mentioned broadbanding treatment, since the pitch of the helical structure can be continuously changed in the thickness direction, the wavelength range (reflection band) in which the layer of the cured product of the cholesteric liquid crystal composition can exhibit a circular polarization separation function can be expanded, and therefore, it is called a broadbanding treatment.

[0040] The polarization separation layer preferably includes a cured product layer formed only of a cured product of a cholesteric liquid crystal composition. This cured product layer may be a single-layer structure layer consisting of only one layer, or may be a multi-layer structure layer including two or more layers. From the viewpoint of ease of manufacture, the number of layers included in the cured product layer is preferably 1 to 100, and more preferably 1 to 20.

[0041] Among them, the polarization separation layer preferably includes only the above-mentioned cured product layer. That is, it is preferable that the polarization separation layer is a cured product layer formed only of a cured product of a cholesteric liquid crystal composition. In this case, since the polarization separation layer does not include any arbitrary layers such as a support layer, the polarization separation layer can be made thin. In addition, the polarization separation layer formed only of a cured product of a cholesteric liquid crystal composition in this way can be provided on the surface of the yarn base material by a simple method.

[0042] The polarization separation layer preferably has a uniform composition in the longitudinal direction of the composite yarn. In addition, the polarization separation layer preferably has a uniform composition in the circumferential direction of the composite yarn. Furthermore, the polarization separation layer preferably has a uniform composition in the radial direction of the composite yarn. The polarization separation layer having such a uniform composition can be provided on the surface of the yarn base material by a simple method.

[0043] Since the polarization separation layer contains a cured product of a cholesteric liquid crystal composition, it usually contains molecules of a liquid crystalline compound. The molecules of this liquid crystalline compound may have their orientation states fixed by reactions such as polymerization and crosslinking. According to the above reactions, the liquid crystallinity usually possessed by the liquid crystalline compound is lost, but the liquid crystalline compound with the orientation state fixed as described above is also included in the liquid crystalline compounds contained in the polarization separation layer. At this time, the orientation state of the liquid crystalline compound contained in the polarization separation layer is preferably continuous in one or both of the longitudinal direction and the circumferential direction of the composite fiber. That is, in one or both of the longitudinal direction and the circumferential direction of the composite fiber, it is preferable that there is no portion in the polarization separation layer where the orientation state of the liquid crystalline compound is discontinuous. Usually, when a composite fiber illuminated with non-polarized light is observed through a circular polarizing plate, a portion where the orientation state of the liquid crystalline compound is discontinuous is visually recognized as a portion where the luminance is discontinuously different from the surroundings. Therefore, it is preferable that there is no such portion in the polarization separation layer where the luminance is discontinuously different from the surroundings.

[0044] In a preferred embodiment, the molecules of the liquid crystalline compound in the polarization separation layer are oriented according to the orientation regulating force possessed by the surface of the fiber base material. Therefore, preferably, all the molecules of the liquid crystalline compound on the surface of the fiber base material side of the polarization separation layer are oriented in one direction corresponding to the orientation regulating force possessed by the surface of the fiber base material. Therefore, it is preferable that the orientation direction of the molecules of the liquid crystalline compound on the surface of the fiber base material side of the polarization separation layer is constant. The orientation direction of the molecules of the liquid crystalline compound represents the direction showing the maximum refractive index in the refractive index ellipsoid of the molecules.

[0045] Generally, among the liquid crystalline compounds contained in the layer of the cured product of the cholesteric liquid crystal composition formed on a certain surface, the molecules of the liquid crystalline compound on the surface of the fiber base material side are all oriented in a direction parallel to the above surface. Therefore, in the above preferred embodiment where the liquid crystalline compound is oriented according to the orientation regulating force possessed by the surface of the fiber base material, the orientation direction of the molecules of the liquid crystalline compound on the surface of the fiber base material side of the layer of the cured product of the cholesteric liquid crystal composition is usually parallel to the surface of the fiber base material.

[0046] Since the polarization separation layer contains a cured product of a cholesteric liquid crystal composition, it can exhibit a circular polarization separation function. Therefore, the polarization separation layer can reflect circularly polarized light with one of the clockwise and counterclockwise rotation directions and transmit circularly polarized light with the opposite rotation direction in the selective reflection range. From the viewpoint of realizing a display mode visible to the naked eye, the selective reflection range is preferably in the visible wavelength region. The visible wavelength region generally refers to the wavelength range of 400 nm or more and 780 nm or less.

[0047] The wavelength width of the selective reflection range of the polarization separation layer is preferably set appropriately according to the color exhibited by the polarization separation layer. Among them, from the viewpoint of enhancing the difficulty of forgery, the wavelength width of the selective reflection range is preferably wide. Specifically, it is preferably 70 nm or more, more preferably 100 nm or more, still more preferably 200 nm or more, and particularly preferably 400 nm or more. The polarization separation layer having such a wide selective reflection range can reflect circularly polarized light of a wide range of colors. The upper limit of the wavelength width of the selective reflection range is not particularly limited, but it can be, for example, 600 nm or less.

[0048] The circular polarization characteristics of the polarization separation layer can be selected according to the design of the composite fiber. The circular polarization characteristics represent the rotation direction of the circularly polarized light reflected in the selective reflection range. Therefore, the polarization separation layer may have circular polarization characteristics that can reflect clockwise circularly polarized light and transmit counterclockwise circularly polarized light. This polarization separation layer has a right circular polarization reflection range as a wavelength range that can selectively reflect right circularly polarized light, and in this right circular polarization reflection range, it can reflect clockwise circularly polarized light and transmit counterclockwise circularly polarized light. Also, the polarization separation layer may have circular polarization characteristics that can reflect counterclockwise circularly polarized light and transmit clockwise circularly polarized light. This polarization separation layer has a left circular polarization reflection range as a wavelength range that can selectively reflect left circularly polarized light, and in this left circular polarization reflection range, it can reflect counterclockwise circularly polarized light and transmit clockwise circularly polarized light.

[0049] The circular polarization characteristics of the polarization separation layer can be adjusted by the twist direction in the cholesteric regularity of the cholesteric resin composition. Further, the twist direction can be adjusted, for example, by the structure of the chiral agent contained in the cholesteric liquid crystal composition. To give a specific example, when the twist is clockwise, a cholesteric liquid crystal composition containing a chiral agent that imparts dextrorotation can be used, and when the twist direction is counterclockwise, a cholesteric liquid crystal composition containing a chiral agent that imparts levorotation can be used.

[0050] The thickness of the polarization separation layer is preferably 2 μm or more, more preferably 3 μm or more, preferably 20 μm or less, and more preferably 10 μm or less. When the thickness of the polarization separation layer is equal to or greater than the lower limit value of the above range, effective reflection of polarized light becomes possible. Further, when the thickness of the polarization separation layer is equal to or less than the upper limit value of the above range, the transparency of the polarization separation layer can be enhanced.

[0051] [4. Any Component] The composite fiber may further contain any element in combination with the fiber base material and the polarization separation layer as long as the effects of the present invention are not significantly impaired. For example, the composite fiber may include any layer that covers the outside of the polarization separation layer. Examples of such an arbitrary layer include a mat layer for improving slipperiness; a hard coat layer; an antireflection layer; an antifouling layer; and the like. These arbitrary layers preferably have a small in-plane retardation. The specific in-plane retardation of the arbitrary layer is preferably 20 nm or less, more preferably 10 nm or less, particularly preferably 5 nm or less, and ideally 0 nm. Since a layer having a small in-plane retardation is an optically isotropic layer, a change in the polarization state due to the arbitrary layer can be suppressed.

[0052] [5. Characteristics of Composite Fiber] Since the composite yarn includes a polarization separation layer, a new display mode utilizing polarization can be realized. For example, a new display mode can be realized in which the image of the composite yarn visible when illuminated with light including circularly polarized light that the polarization separation layer can reflect is different from the image of the composite yarn visible when illuminated with light not including circularly polarized light that the polarization separation layer can reflect. Also, for example, a new display mode can be realized in which the image of the composite yarn visible through a right circular polarizing plate that can transmit right circularly polarized light and block left circularly polarized light is different from the image of the composite yarn visible through a left circular polarizing plate that can transmit left circularly polarized light and block right circularly polarized light.

[0053] Further, since the composite yarn includes a yarn base material as a core material, it can have high mechanical strength. Therefore, the composite yarn can be used in a wide range of applications where conventional yarns are used.

[0054] The diameter (thickness) of the composite yarn is not particularly limited, but can preferably be 50 μm or more, more preferably 100 μm or more, particularly preferably 150 μm or more, and can preferably be 300 μm or less, more preferably 250 μm or less, particularly preferably 200 μm or less.

[0055] [6. Method for manufacturing composite yarn] The above-described composite yarn can be manufactured by a manufacturing method including, in this order, step (I) of preparing a yarn base material, step (II) of forming a layer of a cholesteric liquid crystal composition on the surface of the yarn base material, step (III) of orienting the cholesteric liquid crystal composition, and step (IV) of curing the cholesteric liquid crystal composition.

[0056] - Step (I) - In step (I), the above-described yarn base material is prepared. Generally, the yarn base material can be stretched under tension in the length direction during the production, winding, and unwinding of the yarn base material. Due to this stretching, an orientation regulating force can be imparted to the surface of the yarn base material. In particular, when the yarn base material is a drawn yarn, the drawn yarn can have a large orientation regulating force.

[0057] Therefore, when a layer containing a liquid crystalline compound is usually formed on the surface of the yarn substrate, the yarn substrate can have an orientation regulating force for orienting the molecules of the liquid crystalline compound. In the method for producing a composite yarn described in the present embodiment, the cholesteric liquid crystal composition can be oriented by utilizing the above-described orientation regulating force possessed by the surface of the yarn substrate.

[0058] - Step (V)- The method for producing a composite yarn may include, as an optional step before step (II), a step (V) of subjecting the prepared yarn substrate to a treatment for enhancing the orientation regulating force. Examples of this treatment include a stretching treatment. However, even if this treatment is not performed, the yarn substrate can generally have a sufficiently large orientation regulating force. Therefore, the method for producing a composite yarn may not include step (V).

[0059] - Step (II)- In step (II), a layer of a cholesteric liquid crystal composition is formed on the surface of the yarn substrate. There is no limitation on the method for forming the layer of the cholesteric liquid crystal composition, but usually, a liquid cholesteric liquid crystal composition is prepared, and this cholesteric liquid crystal composition is applied to the surface of the yarn substrate to form a layer of the cholesteric liquid crystal composition.

[0060] The liquid cholesteric liquid crystal composition usually contains a solvent in combination with a liquid crystalline compound. The cholesteric liquid crystal composition may contain a liquid crystalline compound and, if necessary, any optional components (for example, a chiral agent, a crosslinking agent, a polymerization initiator, a surfactant, a polymerization inhibitor, an oxidation inhibitor, an ultraviolet absorber, a light stabilizer, etc.). However, when the cholesteric liquid crystal composition contains a solvent, the liquid crystalline compound and any optional components can be dissolved or dispersed in the solvent. Such a liquid cholesteric liquid crystal composition is easy to apply to the surface of the yarn substrate, so that the formation of the layer of the cholesteric liquid crystal composition can be easily performed.

[0061] The amount of the solvent is preferably set so that the solid content concentration of the cholesteric liquid crystal composition can be adjusted within an appropriate range. Here, the solid content refers to components other than the solvent contained in the cholesteric liquid crystal composition. The solid content concentration of the cholesteric liquid crystal composition is preferably 5% by weight or more, more preferably 10% by weight or more, particularly preferably 15% by weight or more, and preferably 50% by weight or less, more preferably 45% by weight or less, particularly preferably 40% by weight or less. When the solid content concentration of the cholesteric liquid crystal composition is within the above range, the viscosity of the cholesteric liquid crystal composition can be adjusted within an appropriate range to obtain excellent coatability.

[0062] Examples of the coating method of the cholesteric liquid crystal composition include, for example, a spray coating method, a dip coating method, and the like. Among them, the dip coating method is preferable.

[0063] The dip coating method coats the surface of the yarn substrate with the cholesteric liquid crystal composition by a method including immersing the yarn substrate in the cholesteric liquid crystal composition. For example, the yarn substrate is immersed in the cholesteric liquid crystal composition stored in an appropriate container, and then the yarn substrate is taken out from the cholesteric liquid crystal composition. This operation can be performed while transporting the yarn substrate in the longitudinal direction so that the yarn substrate is temporarily submerged in the cholesteric liquid crystal composition. Since the cholesteric liquid crystal composition adheres to the surface of the taken-out yarn substrate, formation of a layer of the cholesteric liquid crystal composition on the surface of the yarn substrate can be achieved.

[0064] Since the dip coating method can be performed while continuously transporting the yarn substrate in the longitudinal direction, continuous formation of a layer of the cholesteric liquid crystal composition is possible. Further, in the dip coating method, even when the yarn substrate is transported at high speed, a sufficient amount of the cholesteric liquid crystal composition can be adhered to the surface of the yarn substrate, so that formation of a layer of the cholesteric liquid crystal composition at high speed is possible.

[0065] In the above dip coating method, it is preferable to take out the yarn substrate from the cholesteric liquid crystal composition at an appropriate pulling-up speed. The specific pulling-up speed is preferably 0.5 m / min or more, more preferably 1.0 m / min or more, still more preferably 1.5 m / min or more, and preferably 5 m / min or less, more preferably 4 m / min or less, still more preferably 3 m / min or less.

[0066] - Step (III)- In Step (III), the cholesteric liquid crystal composition contained in the layer formed on the surface of the yarn substrate is aligned. By this alignment, the molecules of the liquid crystalline compound contained in the cholesteric liquid crystal composition are aligned according to the alignment regulating force on the surface of the yarn substrate, so that the cholesteric liquid crystal composition containing the molecules can exhibit a cholesteric liquid crystal phase.

[0067] The alignment may proceed without any special treatment, but in order to promote the alignment, it is preferable to perform an alignment treatment of adjusting the temperature of the layer of the cholesteric liquid crystal composition to an appropriate alignment temperature. It is preferable to select an appropriate temperature according to the composition of the cholesteric liquid crystal composition. For example, 50°C to 150°C is preferable. Also, the alignment time for bringing the temperature of the cholesteric liquid crystal composition to the above alignment temperature can be, for example, 0.5 minutes to 10 minutes.

[0068] - Step (VI)- After Step (III), a step (VI) of performing a broadbanding treatment for widening the pitch of the helical structure of the cholesteric liquid crystal phase may be performed. This step (VI) is usually performed before Step (IV). The broadbanding treatment can be performed by a combination of irradiation treatment with active energy rays one or more times and heating treatment.

[0069] The irradiation treatment in the broadbanding treatment can be performed, for example, by irradiating light with a wavelength of 200 nm to 500 nm for 0.01 seconds to 3 minutes. At this time, the energy of the irradiated light is, for example, 0.01 mJ / cm 2 ~50 mJ / cm 2This is possible. Further, the heat treatment can be carried out, for example, by heating to a temperature preferably of 40°C or higher, more preferably 50°C or higher, preferably 200°C or lower, and more preferably 140°C or lower. The heating time at this time can preferably be 1 second or longer, more preferably 5 seconds or longer, and preferably 3 minutes or shorter, and more preferably 120 seconds or shorter.

[0070] By performing such a broadbanding process, the pitch size of the helical structure of the cholesteric liquid crystal phase can be continuously and greatly changed in the thickness direction of the cholesteric liquid crystal composition, so that the selective reflection range can be widened. The irradiation of the active energy ray may be carried out in air, or a part or all of the process may be carried out in an atmosphere with controlled oxygen concentration. Examples of the atmosphere with controlled oxygen concentration include an inert atmosphere such as nitrogen and argon.

[0071] - Step (IV)- In step (IV), the cholesteric liquid crystal composition is cured. By curing the cholesteric liquid crystal composition in a state presenting a cholesteric liquid crystal phase, a polarization separation layer including a cured product of the cholesteric liquid crystal composition having a circular polarization separation function can be formed on the surface of the yarn substrate to obtain a composite yarn.

[0072] The curing of the layer of the cholesteric liquid crystal composition can be carried out by polymerizing a polymerizable component such as a polymerizable liquid crystalline compound contained in the cholesteric liquid crystal composition. As the polymerization method, a method suitable for the properties of the components contained in the liquid crystal composition can be selected. Examples of the polymerization method include a method of irradiating active energy rays and a thermal polymerization method. Among them, since the polymerization reaction can proceed at room temperature, the method of irradiating active energy rays is preferred. When curing the layer of the cholesteric liquid crystal composition by irradiating active energy rays, the intensity of the active energy rays irradiated can be, for example, 50 mJ / cm 2 ~10,000 mJ / cm 2 This is possible. The above-mentioned irradiation of the active energy ray may be carried out in air, or a part or all of the process may be carried out in an atmosphere with controlled oxygen concentration.

[0073] - Any process - The method for producing the composite yarn may further include any arbitrary process in combination with the above-described processes. For example, the method for producing the composite yarn may include a process of drying the cholesteric liquid crystal composition after forming a layer of the cholesteric liquid crystal composition on the surface of the yarn base material in step (II). By drying, the solvent can be removed from the layer of the cholesteric liquid crystal composition. However, usually, drying can also proceed simultaneously with alignment in step (III).

[0074] [7. Article comprising the composite yarn] The composite yarn can be used for a wide range of applications where the yarn can be used. Therefore, by using the composite yarn, an article comprising the composite yarn can be provided. This article can realize a new display mode by utilizing the circular polarization separation function of the polarization separation layer of the composite yarn.

[0075] Examples of the article include those comprising an article body and a composite yarn sewn to the article body. Specific examples include an article in which a design such as characters, numbers, figures, patterns, etc. is formed by a composite yarn sewn to the article body, like embroidery. Another specific example includes an article in which a display medium such as a label is sewn to the article body by the composite yarn. Still another specific example includes an article in which a display medium such as a label is tied to the article body by the composite yarn. Still another specific example includes an article in which a plurality of article bodies forming an article, such as clothing and a bag, are sewn together with the composite yarn. In any of the examples, it is possible to provide an impactful new display mode by utilizing the circular polarization separation function of the polarization separation layer of the composite yarn.

[0076] An article may be provided only with a composite yarn for right circular polarization reflection having a polarization separation layer that can reflect right-handed circular polarization and transmit left-handed circular polarization as the composite yarn. Further, an article may be provided only with a composite yarn for left circular polarization reflection having a polarization separation layer that can reflect left-handed circular polarization and transmit right-handed circular polarization as the composite yarn. Furthermore, an article may be provided by combining a composite yarn for right circular polarization reflection and a composite yarn for left circular polarization reflection. Among these, from the viewpoint of realizing a novel design that has not existed before, it is preferable to use a combination of a composite yarn for right circular polarization reflection and a composite yarn for left circular polarization reflection.

[0077] For example, consider a case where a composite yarn for right circular polarization reflection and a composite yarn for left circular polarization reflection are sewn onto an article body so as to form different shapes. In this case, when the article illuminated with unpolarized light such as natural light is observed with the naked eye, both the shape formed by the composite yarn for right circular polarization reflection and the shape formed by the composite yarn for left circular polarization reflection can be visually recognized. Further, when the article is observed through a right circular polarizing plate, the shape formed by the composite yarn for right circular polarization reflection can be visually recognized, but the shape formed by the composite yarn for left circular polarization reflection is not visually recognized. Furthermore, when the article is observed through a left circular polarizing plate, the shape formed by the composite yarn for left circular polarization reflection can be visually recognized, but the shape formed by the composite yarn for right circular polarization reflection is not visually recognized. Therefore, in this case, depending on the presence or absence of the use of a circular polarizing plate and the type of the circular polarizing plate, different shaped observation images can be visually recognized, so that a design with unexpectedness that has not existed before can be realized.

[0078] Also, for example, consider a case where a composite yarn for right circularly polarized light reflection and a composite yarn for left circularly polarized light reflection are mixed nearby and sewn onto an article body. In this case, when observing an article illuminated with unpolarized light such as natural light with the naked eye, it is possible to visually recognize the color mixture of the right circularly polarized light reflected by the composite yarn for right circularly polarized light reflection and the left circularly polarized light reflected by the composite yarn for left circularly polarized light reflection. Also, when observing the article through a right circularly polarized plate, the color of the right circularly polarized light reflected by the composite yarn for right circularly polarized light reflection can be visually recognized, but the color of the left circularly polarized light reflected by the composite yarn for left circularly polarized light reflection is not visually recognized. Further, when observing the article through a left circularly polarized plate, the color of the left circularly polarized light reflected by the composite yarn for left circularly polarized light reflection can be visually recognized, but the color of the right circularly polarized light reflected by the composite yarn for right circularly polarized light reflection is not visually recognized. Therefore, in this case, depending on the presence or absence of the use of a circularly polarized plate and the type of the circularly polarized plate, different color observation images can be visually recognized, so that a design with unexpectedness not found in the past can be realized.

[0079] In the application of actively displaying a design by means of a composite yarn as described above, it is preferable to sew the composite yarn at a position where the article is easily visible. On the other hand, the composite yarn may be sewn at a position where the article is difficult to see. For example, when using a composite yarn for the purpose of identifying the authenticity of an article, since the composite yarn does not need to be actively seen, the purpose can be achieved even if it is provided at a position where it is difficult to see. Specific examples include sewing the composite yarn at a position such as the back side of clothing or the inside of a bag.

[0080] Also, even when a composite yarn is provided at a position where the article is easily visible, the composite yarn can be used for identifying authenticity. Therefore, by using a composite yarn, it is possible to provide an article with high design and high difficulty in forgery.

[0081] The determination of the authenticity of an article provided with a composite yarn is, for example, observing the article through a right circularly polarized plate to obtain a first observation image, observing the article through a left circularly polarized plate to obtain a second observation image, and determining the authenticity of the article based on the first observation image and the second observation image. It can be carried out by a determination method including

[0082] Specifically, the authenticity determination method can be carried out as follows. In this determination method, an article is illuminated with light such as non-polarized light including right-circularly polarized light and left-circularly polarized light, and the article is observed through a right-circularly polarized plate and through a left-circularly polarized plate. In the observation through the right-circularly polarized plate, since the left-circularly polarized light is blocked by the right-circularly polarized plate, a first observation image formed by the right-circularly polarized light can be obtained. Also, in the observation through the left-circularly polarized plate, since the right-circularly polarized light is blocked by the left-circularly polarized plate, a second observation image formed by the left-circularly polarized light can be obtained. Since the composite yarn is provided with a polarization separation layer that selectively reflects one of the right-circularly polarized light and the left-circularly polarized light, when observing a genuine article provided with the composite yarn, the first observation image and the second observation image are different. However, when observing a non-genuine article, the first observation image and the second observation image are the same. Therefore, when the first observation image and the second observation image are different, the article can be determined to be genuine. Also, when the first observation image and the second observation image are the same, the article can be determined to be non-genuine.

[0083] Examples of the article body to which the composite yarn can be applied as described above include, for example, fabric products such as clothing; leather products such as bags and shoes; metal products such as screws; paper products such as price tags; rubber products such as tires; plastic containers for food; glass containers for food; plastic containers for pharmaceuticals; and glass containers for pharmaceuticals. However, the article body is not limited to these examples.

Example

[0084] Hereinafter, the present invention will be specifically described by showing examples. However, the present invention is not limited to the examples shown below, and can be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and its equivalent scope.

[0085] In the following description, “%” and “parts” representing amounts are based on weight unless otherwise specified. Also, the following operations were carried out in the normal temperature and pressure atmosphere unless otherwise specified.

[0086] [Production Example 1: Production of Solution (G) Containing a Cholesteric Liquid Crystal Composition Capable of Reflecting Right Circularly Polarized Light of Green Color] 100 parts of a photopolymerizable liquid crystalline compound represented by the following formula (X1), 25 parts of a photopolymerizable non-liquid crystalline compound represented by the following formula (X2), 8 parts of a chiral agent ("LC756" manufactured by BASF), 5 parts of a photopolymerization initiator ("Irgacure 379" manufactured by Ciba Japan Co., Ltd.), 0.15 part of a surfactant ("S-420" manufactured by AGC Seimi Chemical Co., Ltd.), 128 parts of cyclopentanone and 192 parts of dioxolane as solvents were mixed to produce a solution (G) containing a cholesteric liquid crystal composition capable of reflecting right circularly polarized light of green color.

[0087]

Chemical formula

[0088]

Chemical formula

[0089] [Production Example 2: Production of Solution (R) Containing a Cholesteric Liquid Crystal Composition Capable of Reflecting Right Circularly Polarized Light of Red Color] A solution (R) containing a cholesteric liquid crystal composition capable of reflecting right circularly polarized light of red color was produced in the same manner as in Production Example 1, except that 7 parts of a chiral agent ("LC756" manufactured by BASF) was used instead of 8 parts of the chiral agent ("LC756" manufactured by BASF).

[0090] [Production Example 3: Production of Solution (GL) Containing a Cholesteric Liquid Crystal Composition Capable of Reflecting Left (Reverse Right) Circularly Polarized Light of Green Color] A solution (GL) containing a cholesteric liquid crystal composition capable of reflecting left (reverse right) circularly polarized light of green color was produced in the same manner as in Production Example 1, except that 8 parts of D-mannitol, 1,4:3,6-dihydro-, 2,5-bis[4-[[[6-[[[4-[(1-oxo-2-propen-1-yl)oxy]butoxy]carbonyl]oxy]-2-naphthalenyl]carbonyl]oxy]benzoate shown in the following formula (X3) was used instead of 8 parts of the chiral agent ("LC756" manufactured by BASF).

[0091]

Chem.

[0092] [Production Example 4: Production of a Solution (RL) Containing a Cholesteric Liquid Crystal Composition Capable of Reflecting Left (Reverse Right) Circularly Polarized Light of Red Color] A solution (RL) containing a cholesteric liquid crystal composition capable of reflecting left (reverse right) circularly polarized light of red color was produced in the same manner as in Production Example 1, except that 7 parts of D-mannitol, 1,4:3,6-dihydro-, 2,5-bis[4-[[[6-[[[4-[(1-oxo-2-propen-1-yl)oxy]butoxy]carbonyl]oxy]-2-naphthalenyl]carbonyl]oxy]benzoate] represented by the above formula (X3) was used instead of 8 parts of the chiral agent ("LC756" manufactured by BASF).

[0093] [Production Example 5: Production of a Solution (B) Containing a Cholesteric Liquid Crystal Composition Capable of Reflecting Right Circularly Polarized Light of Blue Color] A solution (B) containing a cholesteric liquid crystal composition capable of reflecting right circularly polarized light of blue color was produced in the same manner as in Production Example 1, except that the amount of the chiral agent ("LC756" manufactured by BASF) was changed to 10 parts.

[0094] [Example 1] (1.1. Production of a Composite Yarn (CLC_G) Capable of Reflecting Right Circularly Polarized Light of Green Color) As a yarn substrate, a colorless and transparent nylon fishing line (manufactured by Shimano; thickness 0.3 mm) was prepared. The solution (G) of the cholesteric liquid crystal composition produced in Production Example 1 was applied to this yarn substrate by the dip coating method. Specifically, the yarn substrate was immersed in the solution (G), and then pulled up to apply the solution (G) to the surface of the yarn substrate. The pulling-up speed of the yarn substrate was 2 m / min.

[0095] Thereafter, the thread base material and the solution (G) on its surface were heat-treated at 120°C for 4 minutes. By this heat treatment, removal of the solvent by drying and alignment treatment of the cholesteric liquid crystal composition were performed, so that a layer of the cholesteric liquid crystal composition exhibiting a cholesteric liquid crystal phase was formed on the surface of the thread base material. Thereafter, ultraviolet rays of 800 mJ / cm 2 were irradiated onto the layer of the cholesteric liquid crystal composition to cure it. As a result, a composite thread (CLC_G) was obtained which included the thread base material and a polarization separation layer formed by a cured product of the cholesteric liquid crystal composition on the surface of this thread base material. The composite thread (CLC_G) had a green reflection visually.

[0096] (1.2. Manufacture of an article using the composite thread (CLC_G)) FIG. 2 is a plan view schematically showing the embroidery formed in Example 1 of the present invention. In FIG. 2, the eyes of the sewn composite threads (CLC_G) 10 are each shown as a rectangular block. In this FIG. 2, the eyes of the sewn composite threads (CLC_G) 10 are shown large, but in the actually formed embroidery, the eyes of the composite threads (CLC_G) 10 were formed finer. As shown in FIG. 2, the above-mentioned composite thread (CLC_G) 10 was sewn onto a black cloth to form an embroidery in the shape of the number "1088".

[0097] (1.3. Observation through a circular polarizing plate) A cloth with embroidery formed as described above was placed on a horizontal table. While illuminating the cloth with the embroidery formed with a fluorescent lamp as an unpolarized light source, observation was made through a circular polarizing plate to examine whether the embroidery could be visually recognized. Specifically, observation was performed using a right circular polarizing plate that transmits right circular polarization and blocks left circular polarization, and observation was performed using a left circular polarizing plate that transmits left circular polarization and blocks right circular polarization.

[0098] [Example 2: Manufacture and evaluation of a composite thread (CLC_B) that can reflect blue right circular polarization] Except for using solution (B) containing the cholesteric liquid crystal composition produced in Production Example 5 instead of solution (G) of the cholesteric liquid crystal composition, the composite yarn (CLC_B) was produced, embroidery was formed using the composite yarn (CLC_B), and observation of the embroidery through a circular polarizing plate was carried out in the same manner as in Example 1. The composite yarn (CLC_B) had a blue reflection when viewed visually.

[0099] [Example 3: Production and Evaluation of Composite Yarn (CLC_R) Capable of Reflecting Right Circular Polarization of Red Color] Except for using solution (R) containing the cholesteric liquid crystal composition produced in Production Example 2 instead of solution (G) of the cholesteric liquid crystal composition, the composite yarn (CLC_R) was produced, embroidery was formed using the composite yarn (CLC_R), and observation of the embroidery through a circular polarizing plate was carried out in the same manner as in Example 1. The composite yarn (CLC_R) had a red reflection when viewed visually.

[0100] [Example 4: Production and Evaluation of Composite Yarn (CLC_GL) Capable of Reflecting Left (Reverse Right) Circular Polarization of Green Color] Except for using solution (GL) containing the cholesteric liquid crystal composition produced in Production Example 3 instead of solution (G) of the cholesteric liquid crystal composition, the composite yarn (CLC_GL) was produced, embroidery was formed using the composite yarn (CLC_GL), and observation of the embroidery through a circular polarizing plate was carried out in the same manner as in Example 1. The composite yarn (CLC_GL) had a green reflection when viewed visually.

[0101] [Example 5: Production and Evaluation of Yarn (CLC_RL) Capable of Reflecting Left (Reverse Right) Circular Polarization of Red Color] Except for using solution (RL) containing the cholesteric liquid crystal composition produced in Production Example 4 instead of solution (G) of the cholesteric liquid crystal composition, the composite yarn (CLC_RL) was produced, embroidery was formed using the composite yarn (CLC_RL), and observation of the embroidery through a circular polarizing plate was carried out in the same manner as in Example 1. The composite yarn (CLC_RL) had a red reflection when viewed visually.

[0102] [Example 6: Manufacture and Evaluation of Composite Yarn (CLC_W) Capable of Reflecting Broadband Right-Circularly Polarized Light] The composite yarn (CLC_W) was manufactured, embroidery was formed using the composite yarn (CLC_W), and the embroidery was observed through a circular polarizing plate in the same manner as in Example 1, except that a layer of a cholesteric liquid crystal composition was formed on the surface of the yarn substrate and the layer of the cholesteric liquid crystal composition was subjected to a broadband treatment before being cured.

[0103] Specifically, in the same manner as in Example 1, Solution (G) was applied to the surface of the yarn substrate and heat-treated to form a layer of a cholesteric liquid crystal composition. Thereafter, the layer of the cholesteric liquid crystal composition was subjected to a broadband treatment. In this broadband treatment, weak ultraviolet irradiation of 5 mJ / cm 2 ~30 mJ / cm 2 and heat treatment at 100°C to 120°C were alternately repeated a plurality of times to control the wavelength width of the selective reflection range of the obtained circular polarization separation layer to a desired bandwidth. Thereafter, the layer of the cholesteric liquid crystal composition was irradiated with ultraviolet light of 800 mJ / cm 2 and cured. As a result, a composite yarn (CLC_W) including the yarn substrate and a polarization separation layer formed of a cured product of a cholesteric liquid crystal composition on the surface of the yarn substrate was obtained. The composite yarn (CLC_W) had a silver-colored broadband reflection visually. Using this composite yarn (CLC_W), embroidery was formed and the embroidery was observed through a circular polarizing plate in the same manner as in Example 1.

[0104] [Example 7: Manufacture and Evaluation of Composite Yarn (CLC_Gb) Capable of Reflecting Green Right-Circularly Polarized Light and Having a Black Yarn Substrate] The composite yarn (CLC_Gb) was manufactured, embroidery was formed using the composite yarn (CLC_Gb), and the embroidery was observed through a circular polarizing plate in the same manner as in Example 1, except that a black nylon fishing line (manufactured by Daiwa; thickness 0.3 mm) was used as the yarn substrate. The composite yarn (CLC_Gb) had a green reflection visually.

[0105] [Example 8: Production and Evaluation of Composite Yarn (CLC_Gr) Capable of Reflecting Green Right Circular Polarization and Having a Cotton Twisted Yarn as Yarn Substrate] Except for using a black cotton twisted yarn (manufactured by Kurobara Co., Ltd.; thickness of about 0.3 mm) as the yarn substrate, the composite yarn (CLC_Gr) was produced, embroidery was formed using the composite yarn (CLC_Gr), and observation of the embroidery through a circular polarizing plate were carried out in the same manner as in Example 1. The composite yarn (CLC_Gr) had a green reflection visually.

[0106] [Example 9: Production of Composite Yarn (CLC_GLr) Capable of Reflecting Green Left (Reverse Right) Circular Polarization and Having a Cotton Twisted Yarn as Yarn Substrate] Instead of the solution (G) of the cholesteric liquid crystal composition, a solution (GL) containing the cholesteric liquid crystal composition produced in Production Example 3 was used. Also, as the yarn substrate, the same black cotton twisted yarn (manufactured by Kurobara Co., Ltd.; thickness of about 0.3 mm) as that used in Example 8 was used. Except for the above matters, the composite yarn (CLC_GLr) was produced, embroidery was formed using the composite yarn (CLC_GLr), and observation of the embroidery through a circular polarizing plate were carried out in the same manner as in Example 1. The composite yarn (CLC_GLr) had a green reflection visually.

[0107] [Example 10: Production and Evaluation of Composite Yarn (CLC_GrR) Capable of Reflecting Green Right Circular Polarization and Having a Cotton Twisted Yarn as Yarn Substrate] The same black cotton twisted yarn (manufactured by Kurobara Co., Ltd.; thickness of about 0.3 mm) as that used in Example 8 was prepared. This twisted yarn was passed between folded rubbing cloths at a speed of 2 m / min to perform a rubbing treatment in the longitudinal direction on the surface of the twisted yarn. Except for using the twisted yarn thus rubbed as the yarn substrate, the composite yarn (CLC_GrR) was produced, embroidery was formed using the composite yarn (CLC_GrR), and observation of the embroidery through a circular polarizing plate were carried out in the same manner as in Example 1. The composite yarn (CLC_GrR) had a green reflection visually.

[0108] [Results of Examples 1 - 10] The results of observing the embroidery obtained in the above Examples 1 to 10 through a right circular polarizing plate and through a left circular polarizing plate are shown in Table 1 below. In Table 1, the meanings of the symbols are as follows. [Recognition criteria] ×: It was difficult to recognize the color and pattern of the embroidery. △: The color and pattern of the embroidery were faintly recognizable. 〇: The color and pattern of the embroidery were clearly recognizable. ◎: Both the color and pattern of the embroidery were more clearly and distinctly recognizable. The visibility was significantly higher than in the state of "〇" above.

[0109]

Table 1

[0110] [Examination of Examples 1 to 10] As shown in Table 1, the embroideries produced in Examples 1 to 10 were all such that the color and visibility exhibited by each composite yarn changed according to the circular polarization characteristics of the circular polarizing plate. It can be seen that when observing through a circular polarizing plate having circular polarization characteristics opposite to those of the cholesteric liquid crystal composition used in each composite yarn, it is possible to block that information. Also, it was confirmed that by making the yarn substrate a dark color, the visibility is further improved. It became clear that it is actually possible to manufacture such a special composite yarn having such characteristics. When the yarn substrate is made of cotton yarn, it was confirmed that although the polarization characteristics are slightly inferior, the same effect can be exhibited, and the effect is the same even when the surface of the yarn substrate is rubbed.

[0111] [Example 11] (11.1. Manufacture of an article using composite yarn (CLC_G) and composite yarn (CLC_GL)) Figure 3 is a plan view schematically showing the embroidery formed in Example 11 of the present invention. In Figure 3, the eyes of the sewn composite yarn (CLC_G) 11 are shown as white blocks, and the eyes of the composite yarn (CLC_GL) 12 are shown as black rectangular blocks. In this Figure 3, the eyes of the sewn composite yarn (CLC_G) 11 and the composite yarn (CLC_GL) 12 are shown large, but in the actually formed embroidery, the eyes of the composite yarn (CLC_G) 11 and the composite yarn (CLC_GL) 12 are formed finer.

[0112] As shown in Figure 3, the composite yarn (CLC_G) 11 manufactured in Example 1 and the composite yarn (CLC_GL) 12 manufactured in Example 4 were sewn onto a black cloth to form embroidery. At this time, the composite yarn (CLC_G) 11 was sewn so as to form an embroidery in the shape of the number "1111", and the composite yarn (CLC_GL) 12 was sewn so as to form an embroidery in the shape of the character string "CEE". With the whole of the composite yarn (CLC_G) 11 and the composite yarn (CLC_GL) 12, an embroidery in the shape of the number "1088" was formed when viewed with the naked eye.

[0113] (11.2. Observation through a circular polarizing plate) A cloth with embroidery formed as described above was placed on a horizontal table. While illuminating the cloth with the embroidery formed with a fluorescent lamp as an unpolarized light source, the color and shape of the visible embroidery were examined. The observation was carried out with the naked eye, with a right circular polarizing plate, and with a left circular polarizing plate.

[0114] As a result of observation with the naked eye, a green embroidery having the shape of the number "1088" was visually recognized. As a result of observation through the right circular polarizing plate, a green embroidery having the shape of the number "1111" was visually recognized. As a result of observation through the left circular polarizing plate, a green embroidery having the shape of the character string "CEE" was visually recognized.

[0115] [Example 12] (12.1. Manufacture of an article using a composite yarn (CLC_G) and a composite yarn (CLC_RL)) Figure 4 is a plan view schematically showing the embroidery formed in Example 12 of the present invention. In Figure 4, the eyes of the sewn composite yarn (CLC_G) 11 are shown as white blocks, and the eyes of the composite yarn (CLC_RL) 13 are shown as black rectangular blocks. In this Figure 4, the eyes of the sewn composite yarn (CLC_G) 11 and the composite yarn (CLC_RG) 13 are shown large, but in the actually formed embroidery, the eyes of the composite yarn (CLC_G) 11 and the composite yarn (CLC_RG) 13 are formed finer.

[0116] As shown in Figure 4, the composite yarn (CLC_G) 11 manufactured in Example 1 and the composite yarn (CLC_RL) 13 manufactured in Example 5 were sewn onto a black cloth to form an embroidery in the shape of the number "1088". When forming this embroidery, the composite yarn (CLC_G) 11 and the composite yarn (CLC_RL) 13 were sewn so that the eyes of the composite yarn (CLC_G) 11 and the eyes of the composite yarn (CLC_RL) 13 were alternately formed.

[0117] (12.2. Observation through a circular polarizing plate) A cloth with embroidery formed as described above was placed on a horizontal table. The cloth with the embroidery formed was observed while being illuminated with a fluorescent lamp as an unpolarized light source to examine the color and shape of the visible embroidery. The observations were made with the naked eye, with a right circular polarizing plate, and with a left circular polarizing plate.

[0118] As a result of observation with the naked eye, an embroidery of a mixed color of green and red having the shape of the number "1088" was visually recognized. As a result of observation through the right circular polarizing plate, a green embroidery having the shape of the number "1088" was visually recognized. Also, as a result of observation through the left circular polarizing plate, a red embroidery having the shape of the number "1088" was visually recognized.

[0119] [Results of Examples 11 - 12] The results of observation through the right circular polarizing plate and observation through the left circular polarizing plate of the embroidery obtained in the above Examples 11 - 12 were summarized in Table 2 below.

[0120]

Table 2

[0121] [Examination of Examples 11 to 12] As shown in Table 2, in Example 11, according to the circular polarization characteristics of the polarization separation layer provided in the composite yarn, the observed embroidery pattern changed among the observed image visually recognized by naked-eye observation, the observed image visually recognized by observation through a right circular polarizing plate, and the observed image visually recognized by observation through a left circular polarizing plate. Also, in Example 12, according to the circular polarization characteristics of the polarization separation layer provided in the composite yarn, the hue of the observed embroidery changed among the observed image visually recognized by naked-eye observation, the observed image visually recognized by observation through a right circular polarizing plate, and the observed image visually recognized by observation through a left circular polarizing plate. Therefore, it was confirmed that by using the composite yarn, it is possible to realize various novel designs, and authenticity determination can be performed by taking advantage of the fact that the observed images are different.

Explanation of Signs

[0122] 10 to 12 Composite yarn 100 Composite yarn 110 Yarn base material 110S Surface of the yarn base material 120 Polarization separation layer

Claims

1. A thread base material, and a polarization separation layer formed on the surface of the thread base material, wherein the polarization separation layer includes a cured product of a cholesteric liquid crystal composition containing a liquid crystalline compound, and molecules of the liquid crystalline compound on the surface of the thread base material side of the polarization separation layer are aligned in one direction parallel to the surface of the thread base material. A thread.

2. The thread according to claim 1, wherein the thread base material is a drawn thread.

3. The thread according to claim 1 or 2, wherein the thread base material is a twisted thread.

4. The thread according to any one of claims 1 to 3, wherein the polarization separation layer is continuously formed in the longitudinal direction and the circumferential direction of the thread base material.

5. The thread according to any one of claims 1 to 4, wherein the diameter of the thread base material is 500 μm or less.

6. The thread according to any one of claims 1 to 5, wherein the thread base material is colored.

7. The thread according to any one of claims 1 to 6, wherein the polarization separation layer can reflect right-handed circularly polarized light and transmit left-handed circularly polarized light.

8. The thread according to any one of claims 1 to 6, wherein the polarization separation layer can reflect left-handed circularly polarized light and transmit right-handed circularly polarized light.

9. A step of preparing a thread base material, a step of forming a layer of a cholesteric liquid crystal composition on the surface of the thread base material, a step of aligning the cholesteric liquid crystal composition, and a step of curing the cholesteric liquid crystal composition, in this order. A method for manufacturing a thread.

10. An article comprising the thread according to any one of claims 1 to 8.

11. An article main body, and the thread sewn to the article main body. The article according to claim 10.

12. The thread is, a thread for right circularly polarized light reflection having a polarization separation layer that can reflect right-handed circularly polarized light and transmit left-handed circularly polarized light, a thread for left circularly polarized light reflection having a polarization separation layer that can reflect left-handed circularly polarized light and transmit right-handed circularly polarized light, and the article according to claim 10 or 11.

13. A method for determining the authenticity of an article according to any one of claims 10 to 12, a step of observing the article through a right circularly polarized plate to obtain a first observation image, a step of observing the article through a left circularly polarized plate to obtain a second observation image, and a step of determining the authenticity of the article based on the first observation image and the second observation image. A method for determining the authenticity of an article.

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