JPH11124747A - Composite yarn having optical interfering function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composite yarn having optical interfering functions, excellent in touch, color developing properties and brightness and useful for a fabric or the like by composing the composite yarn of a high shrinkage yarn and a low shrinkage yarn consisting essentially of a specific light interfering fiber. SOLUTION: This composite yarn comprises a high shrinkage yarn which is a dyed or a spun-dyed fiber having <=40 value of L and further the hue in a relation of complementary color with that of a light interfering fiber and a low shrinkage yarn consisting essentially of the light interfering fiber, composed of an alternate laminate of two or more polymers different in refractive index satisfying requirements of 4-15 flatness ratio, 5-120 number of laminations and 10-60% elongation. The combination of the two polymers different in refractive index is preferably that of (i) a polyester (a high-refractive index polymer) consisting essentially of polyethylene terephthalate in which a dibasic acid component having a metallic sulfonate group is copolymerized in an amount of 0.3-5 mol.% based to the total dibasic acid component forming the polyester with (ii) an aliphatic polyamide (a low-refractive index polymer).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite yarn having a novel optical function, and more particularly, to a composite yarn using a multifilament yarn having an optical function of reflecting, interfering, diffracting, or scattering light. About.

[0002]

2. Description of the Related Art In recent years, due to the demand for high-quality texture of fabrics, sensible fibers such as bulges have been developed by changing from a simple round cross-section yarn to an irregular cross-section and further combining two or more fibers, and flowering as a new synthetic fiber. did. Recently, fibers having higher sensitivity and function have been demanded. One of them is deep color and gloss. However, if you try to satisfy the deep color and gloss at the same time, you can get the deep color effect, but the color becomes dull and loses vividness. And
Heretofore, there has been no technique for achieving both. The reason is that, in the prior art, a color is formed by a dye or a pigment, that is, the color is formed by light absorption. .

On the other hand, when overlooking the natural world, for example, a beetle or a morpho butterfly satisfies both deep color and luster at the same time, and exhibits a color completely different from dyes and pigments. This coloring mechanism is based on light reflection and interference. And
Various approaches have been devised for synthetic fibers utilizing this mechanism. For example, JP-A-7-34320, JP-A-7-34324, and JP-A-7-34324
Japanese Patent No. 331532 discloses a flat optical coherent monofilament having a multilayer thin film structure in which polymers having different refractive indexes (here, optical refractive indexes) are alternately laminated and having an aspect ratio of 3.5 or less.

Natural light incident on the optical coherent monofilament ideally exhibits a reflection spectrum based on multilayer thin film interference, that is, an interference color. However, in fact, the structure has imperfections (such as the thickness of the polymer layer or the thickness of the polymer layer). Due to the wavelength dependence of the refractive index (polymer dispersibility), the wavelength dependence of the absorptivity, etc., a part of the light is transmitted, refracted or scattered, and the so-called "stray light" Act as. This means that the reflection component based on the stray light is superimposed on the reflection spectrum based on the multilayer thin-film interference, thereby impairing the original vivid hue.
For this reason, in the above-mentioned JP-A-7-331532,
As a countermeasure against the above-mentioned stray light, it has been proposed to interweave the optical coherent monofilament and the black-dyed fiber with plain weave, twill weave, satin weave or the like.

[0005] By the way, actual woven fabrics using filaments are usually used in the form of multifilament yarns because of the need to express "feel". Nothing is recognized about textiles.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multifilament yarn capable of sufficiently exhibiting the vivid coloration exhibited by an optical coherent monofilament even when a texture is added.

[0007]

Means for Solving the Problems The present inventors have constituted a multifilament yarn comprising the above-mentioned monofilament as a constitutional unit and a multifilament yarn having a lower boiling water shrinkage ratio than the yarn, thereby forming a composite yarn. We solved that problem.

Thus, according to the present invention, in a composite yarn comprising a high shrinkage yarn (multifilament yarn) and a low shrinkage yarn (multifilament yarn), the main component of the low shrinkage yarn is refraction. The present invention provides a composite yarn having an optical interference function, which is an optical interference fiber composed of an alternating laminate of at least two types of polymers having different ratios.

FIG. 1 is a cross-sectional view of a monofilament constituting a multifilament yarn exhibiting an optical interference function which is an object of the present invention. FIG. 1A shows a shape in which polymers A and B having different refractive indices are alternately laminated in the major axis direction of the flat cross section, and FIG. 1B shows a shape of the hollow flat cross section. -(C) shows the above A, B,
Alternatively, FIG. 1- (d) shows a shape in which a reinforcing portion (membrane) is provided on the outer peripheral portion.

In the present invention, a multifilament yarn having a monofilament as a constituent unit as described above is combined with a multifilament yarn having a higher boiling water shrinkage ratio. There is a great relationship between the color development of the light interference monofilament and the filament arrangement, and the higher the light interference filaments arranged on the yarn surface, the higher the color development. In this sense, in the present invention, a light interference multifilament yarn is provided as a low shrinkage component of the hetero-shrinkage mixed woven yarn which gives the fabric a swelling feeling and a soft feeling.

Further, the light interference filament develops color by interference between incident light and light reflected inside the filament. By the way, the human eye recognizes the color intensity based on the difference between the interference light reflected from other parts and the stray light entering the eye. Therefore, when stray light from the surroundings is strong, even if there is sufficient interference light from inside the filament, it cannot be recognized as a color. As a method for preventing stray light, it is preferable to use a filament yarn having a function of absorbing stray light as a highly shrinkable filament yarn located at a position closest to the light interference fiber, particularly the light interference fiber. In order to absorb stray light, it is preferable to use dyed fibers or soaked fibers having an L value of 40 or less, preferably 30 or less, more preferably 20 or less. In particular, a black filament yarn is preferable because it absorbs light of all wavelengths and has a large effect of removing stray light. In this case, it is more preferable to use a filament having a hue that is complementary to the color of the light interference filament as the high shrinkage component. This is because, in the composite yarn, the light having the same wavelength as the interference light and the interference light in the stray light portion can be used as the reflected light, so that the intensity of the reflected light is further increased, and the color generated by the interference can be taken out as a large one. Because you can.

Although the L value can be read directly by a color difference meter, in the present invention, a type ND-101DC manufactured by Nippon Denshoku Industries Co., Ltd. is used.
The L value was measured with a color difference meter.

The form of the composite yarn in the present invention includes a mixed yarn, a braid, and a covering yarn. Of course, in the case of the covering yarn, it is needless to say that the light interference filament yarn is wound around the highly shrinkable filament yarn.

When such a composite yarn is subjected to a heat shrink treatment in a yarn or cloth state, the high shrinkage filament shrinks more and sinks into the inside (core) of the composite yarn, while the light interference filament becomes a composite yarn. The light interference effect can be largely taken out because it comes to the surface (sheath part).

As described above, in the composite yarn of the low-shrinkage light interference filament and the high-shrinkage filament, in order for the light interference filament to float by the heat shrinkage treatment,
It is preferable that the shrinkage ratio BWS in the boiling water satisfies the following expression. BWS (A) ≦ 20% (1) BWS (B) −BWS (A) ≧ 5% (2) BWS (B) ≦ 30% ... (3)

Here, the shrinkage BWS (A) of the light interference filament having a low shrinkage is preferably 20% or less as shown in the equation (1). If the shrinkage exceeds 20%, a difference in shrinkage from the other filament cannot be sufficiently provided. Further, BWS (A) is particularly preferably 10% or less. On the other hand, the shrinkage BWS (B) of the high shrink filament is 3
Preferably it is less than 0%. If it exceeds 30%, the dimensional change during the shrinkage treatment is too large, so that it is difficult to obtain a desired product. The value of BWS (B) is 25
% Or less is preferable.

Further, (BWS (B) -BWS (A))
Is preferably 5% or more. When it is less than 5%, the optical interference fiber (A) cannot float on the surface of the fabric or braid. Further, the difference in boiling water shrinkage is preferably 7% or more, more preferably 9% or more.

In the present invention, the monofilament has a flatness of 4 to 15 in order to maximize the optical interference effect of the light coherent multifilament yarn as a whole.
It is preferable to use

Here, the oblateness is the length W of the long axis of the oblate cross section.
And the ratio W / T of the length of the short axis to the length T of the minor axis. As for the flatness, 3.5 has been sufficient to obtain optical coherence as a monofilament, as conventionally proposed. However, when a plurality of such monofilaments are collected and used as a multifilament, the flat long axis surfaces of the filaments are randomly arranged and bundled, so that the light interference function cannot be effectively exerted as a whole multifilament yarn. .

However, when the oblateness is a value of 4, preferably 4.5 or more, a self-orientation control function is added to each of the filaments constituting the multifilament yarn, and the flat long axis of each of the constituent filaments is controlled. The multifilament yarns are assembled by assembling such that the surfaces are parallel to each other. That is, such a multifilament is used when a filament is pressed against a take-up roller or a drawing roller in the process of forming the filament, or when wound on a bobbin in a cheese form, or in a process such as knitting or weaving a fabric. Each time, for example, when receiving a superior pressure contact, the flat long axis surfaces of the filaments are gathered so as to be parallel to the pressure contact surface, so the parallelism of the flat long axis surfaces of the constituent filaments in the multifilament is reduced. High, and excellent light interference as a fabric can be obtained.

On the other hand, if the oblateness exceeds 15, the shape becomes excessively thin, so that it is difficult to maintain the cross-sectional shape, and there is a concern that a part of the cross-section may be bent. From this point, the easy-to-handle flatness is preferably 15 or less, particularly preferably 10 or less.

As described above, since the flatness of the monofilament is 4 to 15, which is larger than that of the conventional optical interference monofilament, the number of the alternately laminated layers is at least 5 or more, which is larger than the conventional number of laminated layers. It is better, preferably 15 layers or more, more preferably 20 layers or more, and most preferably 25 layers or more.

According to the theory of optical interference, when the thickness of each layer is equal to the set value, if the number of layers is at least 5 or more and at most 10 layers, the obtained interference light quantity reaches a saturation state. However, in practice, unevenness in thickness occurs inevitably in the spinning process. Therefore, when the number of laminations is about 10, the light interference effect becomes insufficient. In this sense, if the number of layers is preferably 15 or more, more preferably 20 or more,
The aforementioned disadvantages are compensated. On the other hand, the upper limit is 120 layers,
Particularly, considering the complexity of the spinneret and the control of polymer flow, the number of layers is 70.

The elongation of the optically coherent multifilament of the present invention is in the range of 10 to 60%, preferably 2 to 60%.
It is preferably in the range of 0 to 40%. This is because the bifilament index (Δn) is further increased by stretching the multifilament spun and cooled and solidified once, and the difference in the refractive index between the polymers is defined as the difference of “the refractive index of the polymer plus the birefringence of the fiber”. As a result, the difference in the refractive index as a whole is enlarged, and thereby the optical coherence is enhanced.

The method for producing the light coherent multifilament yarn used in the present invention will be described. First, regarding the combination of polymers, a desired refractive index is selected from the group of polyester (polyethylene terephthalate, polyethylene naphthalate, etc.), polycarbonate, polystyrene, polyolefin, polymethacrylate, polyamide (aliphatic polyamide, aromatic polyamide, etc.). What is necessary is just to select suitably according to it. However, among them, the following combinations are particularly preferable from the viewpoint of ensuring compatibility (adhesion) between the respective layers.

(A) Polyester containing polyethylene naphthalate as a main component, in which a dibasic acid component having a sulfonic acid metal base is copolymerized in an amount of 0.3 to 5 mol% based on all dibasic acid components forming the polyester (High refractive index polymer) and aliphatic polyamide (low refractive index polymer). (B) the dibasic acid component having a sulfonic acid metal base is 0.3 to 0.3 to the total dibasic acid components forming the polyester;
Polyester mainly composed of polyethylene terephthalate copolymerized at 10 mol% (high refractive index polymer)
And polymethyl methacrylate having an acid value of 3 or more. (C) a dibasic acid component and / or a glycol component having at least one alkyl group (for example, a methyl group) in a side chain as a copolymer component (for example, neopentylene glycol, bisphenol A or an alkylene oxide adduct thereof), 5 to 3 copolymer components per total repeating unit
A combination of a copolymerized aromatic polyester (high refractive index polymer) copolymerized with 0 mol% and polymethyl methacrylate (low refractive index component).

The above-mentioned two kinds of polymers are spun from a die as shown in FIG. Here, FIG. 2- (a) is a partially cut perspective view showing an example of the base used in the present invention. In the figure, 1 is a distribution plate, 2 is an upper die, 3 is a middle die, 4 is a lower die, and these four disk-shaped components are laminated. Flow paths 5 and 6 are provided for supplying the polymers A and B by separate paths.
The upper base 2 is provided with a flow path for guiding the polymer A to the row of openings 7, and a flow path 6 ′ for guiding the polymer B to the center of the base. The polymer B guided to the center of the middle base 3 passes through a flow path 8 provided radially on the upper surface of the middle base 3 and further to a funnel-shaped part 9 provided parallel to the flow path 8. 10 passes through the upper surface as a band-like flow. As described above, the polymer A flowing out of the row-shaped openings 7 enters the polymer B passing through the upper surface of the weir-like portion 10 in a strip shape, and the polymer A and the polymer B
Flows into the funnel-shaped part 9 in a form of being alternately laminated in layers (see the arrow in FIG. 2). Is enlarged, and the polymer in which a large number of polymers are stacked gradually becomes shorter. Further, the polymer laminar flow emerging from the discharge port 11 is spun through a final spinning port 12 opened in the lower die 4.

FIG. 2B is a cross-sectional view showing a modification of the die when the reinforcing layer (protective layer) shown in FIG. 1 is formed. Here, a reinforcing layer is formed in the vicinity of the funnel-shaped portion 9 of the middle die 3 of the die shown in FIG.
To form a structure in which the polymer is merged with the main polymer stream through an annular polymer reservoir 15 and an annular flow path 16 surrounding the upper part of the spinneret 12 via a gap 14 between the middle die 3 and the lower die 4. Has become.

The spun alternating laminate is wound up and then hot-drawn (separate drawing method), or drawn and wound up as it is after spinning, or drawn by using high-speed spinning. What is necessary is just to wind up as a multifilament yarn corresponding to. Among these, the separate method is the most effective method for increasing the birefringence between the laminated polymers described above.

In the finally obtained monofilament having an alternately laminated structure, the thickness of each polymer layer is preferably 0.01 μm or more and 0.4 μm or less.
On the other hand, the thickness of the reinforcing portion is preferably 2 microns or more. When the thickness is less than 2 microns, the reinforcing layer and the multilayer molded layer are peeled off due to friction occurring in practical use. On the other hand, if it exceeds 10 microns, light absorption and diffuse reflection at the reinforcing portion cannot be ignored, which is not preferable.

The thickness of the monofilament (denier) and the thickness of the multifilament yarn (denier) may be appropriately set in consideration of the texture and performance of the intended woven fabric. Generally, the former is selected from the range of 2 to 30 denier, and the latter is selected from the range of 50 to 300 denier.

[0032]

According to the present invention, a multi-filament structure in which a light interference multifilament yarn and a yarn having a higher boiling water shrinkage ratio than the yarn coexist has the following advantages. a. By subjecting the composite yarn to a heat shrink treatment in a fabric state, the highly shrinkable yarn is sunk into the composite yarn (that is, located at the core), while the light interference multifilament yarn rises to the composite yarn surface, It has a structure that covers the surface of the composite yarn and thus the surface of the fabric. b. At this time, a yarn foot difference occurs between the two yarns, so that the composite yarn as a whole exhibits a swelling feeling and a soft feeling, and a desired texture is realized. At the same time, the surface of the composite yarn is covered with the light interference multifilament yarn,
Light interference is further emphasized, and a clear coloring effect is obtained. c. These effects are due to the fact that in the conventional method, that is, in a cross-woven fabric of an optical coherent monofilament and other fibers, a parallel state occurs in which both yarns are always adjacent to each other on the woven fabric surface. No yarn can be present. Therefore, the light interference effect on the surface of the fabric is lower than that of the composite yarn of the present invention, and at the same time, the significance of the present invention becomes clear when illuminating the fact that the fabric does not have a swelling feeling or a soft feeling. .

[0033]

【Example】

[Examples 1 to 3] Polyethylene naphthalate (intrinsic viscosity: 0.58; naphthalenedicarboxylic acid: 89 mol%) copolymerized with 10 mol% of terephthalic acid and 1 mol% of sodium sulfoisophthalic acid, and nylon 6 (extreme) Viscosity =
1.3) and 2/3 under a volume ratio of 2/3 (composite ratio).
The composite spinning is performed using the die shown in FIG. 2, and the undrawn yarn having a flat cross-section lamination number of 30 shown in FIG. 1D is wound up (spinning speed).
It was wound at 1500 m / min. 110 ° C
Was drawn 2.0 times with a roller type drawing machine composed of a supply roller heated to 170 ° C. and a drawing roller heated to 170 ° C. to obtain a drawn yarn of 90 denier / 12 filaments.
When the film thickness of the two polymer layers at the center of the flat yarn was measured, the polyethylene naphthalate layer was 0.07 μm,
The nylon layer was 0.08 μm, and a green interference color was observed.

Further, a 75 denier / 24 filament of polyethylene terephthalate containing a black pigment having a high shrinkage obtained by copolymerizing various components as shown in Table 1 was used for the light coherent multifilament yarn. The yarn was combined with the heat-set yarn, and entangled with an interlace nozzle. The number of confounds at this time was approximately 30 pieces / m. The filament composite yarn having the light interference effect thus obtained was used for the warp and the weft of the woven fabric to prepare a 4/1 twill woven fabric. Table 1 shows the results.

[0035]

[Table 1]

Examples 4 to 6 Composite spinning was performed in the same manner as in Example 1 except that the number of layers was set to 15. The obtained unstretched yarn was obtained using the same roller-type stretching machine as in Example 1 for 1.8.
It was drawn twice to obtain a drawn yarn of 78 denier / 12 filaments. At this time, 2 in the center of the flat yarn in the long axis direction
When the film thicknesses of the two polymer layers were measured, the polyethylene naphthalate layer was 0.09 μm and the nylon layer was 0.10 μm.
And a red interference color was observed. The flatness of the monofilament was 5.5.

Further, as shown in Table 2, polyethylene naphthalate copolymerized with 5 mol% of 2,2-bis (hydroxyethoxyphenyl) propane (boiling water shrinkage = 21)
%), A composite yarn using the stretched unheated set yarn as a highly shrinkable yarn was prepared (number of entanglements = 35 yarns / m). At this time, the difference in shrinkage of the composite yarn was 12%. This was used for the warp and the weft of the woven fabric to prepare an 8/2 twill woven fabric. Further, using the disperse dye, dyeing was performed at 125 ° C., which is lower than the glass transition temperature (130 ° C.) of the copolymerized polyethylene naphthalate, using the disperse dye. At this time, the light interference fiber was not dyed, and only the high shrinkage fiber (B) was dyed.

[0038]

[Table 2]

[Examples 7 to 9] Polyethylene naphthalate (boiling water shrinkage) obtained by copolymerizing 5 mol% of 2,2-bis (hydroxyethoxyphenyl) propane with the light coherent multifilament yarn obtained in Examples 4 to 6 was used. (Entanglement = 21%) and a drawn unheated set yarn (entanglement number = 35 / m). At this time, the difference in shrinkage of the composite yarn was 13%. A braid is formed using the composite yarn, and a glass transition temperature of the copolymerized polyethylene naphthalate (130) is further determined using a disperse dye.
C.) at a lower temperature of 125.degree. C. with a disperse dye. At this time, the light interference fiber was not dyed, and only the high shrinkage filament yarn was dyed.

[0040]

[Table 3]

[0041]

According to the present invention, a composite yarn using a low shrinkage yarn having a multilayer laminated structure which is effective for reflecting and interfering light and a yarn having a higher shrinkage than the yarn is used to obtain a high light interference effect. A cloth and a braid having both a texture and a texture can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a unit constituting a light coherent multifilament yarn used in the present invention, that is, a monofilament.

FIG. 2 (a) is a partial cross-sectional perspective view of a die used for spinning a light coherent multifilament yarn used in the present invention. (B) is a partial sectional view showing a variation of the base of (a).

[Explanation of symbols]

 Reference Signs List A Polymer layer B Polymer having a different refractive index from polymer layer A 1 Distribution plate 2 Upper ferrule 3 Middle ferrule 4 Lower ferrule 5 Flow path 6 Flow path 7 Row of openings 8 Radial flow path 9 Toroidal section 10 weir 13 reinforced polymer flow path 14 reinforced polymer flow path 15 reinforced polymer flow path 16 reinforced polymer flow path

Continued on front page (72) Inventor Toshimasa Kuroda 3-4-1, Amihara, Ibaraki-shi, Osaka Teijin Limited Inside Osaka Research Center (72) Inventor Kinya Kumazawa 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Automobile Stock In-house (72) Inventor Hiroshi Tabata 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Susumu Shimizu 2-73 Shinmachi, Hiratsuka-shi, Kanagawa Tanaka Kikinzoku Kogyo Co., Ltd. Inventor Akio Sanehara 26 Suzukawa, Isehara-shi, Kanagawa Prefecture Tanaka Kikinzoku Kogyo Co., Ltd.

Claims (17)

[Claims] 1. A composite yarn comprising a high shrinkage yarn and a low shrinkage yarn, wherein the main component of the low shrinkage yarn is an optical interference comprising an alternating laminate of at least two polymers having different refractive indexes. A composite yarn having an optical interference function, which is a conductive fiber. 2. The composite yarn having an optical interference function according to claim 1, wherein the highly shrinkable yarn is a dyed or soaked fiber having an L value of 40 or less. 3. The composite yarn having an optical interference function according to claim 2, wherein the hue of the highly shrinkable yarn has a complementary color with that of the light interference fiber. 4. The optical interference fiber comprises the following (a) to (c):
The composite yarn having an optical interference function according to claim 1, which satisfies the following condition. (A) Flatness: 4 to 15 (b) Number of layers: 5 to 120 (c) Elongation (%): 10 to 60 5. The boiling water shrinkage BWS (A) of a highly shrinkable yarn.
And the boiling water shrinkage BW of the light interference fiber which is a low shrinkage yarn
The following relationship exists with S (B):
4. The composite yarn having an optical interference function according to any one of 4. BWS (A) ≦ 20% (1) BWS (B) −BWS (A) ≧ 5% (2) BWS (B) ≦ 30% ... (3) 6. The composite yarn according to claim 1, wherein the composite yarn is a mixed yarn of a high shrinkage yarn and a light interference fiber which is a low shrinkage yarn.
A composite yarn having an optical interference function according to any one of the above. 7. The optical interference function according to claim 1, wherein the composite yarn is a composite braid including a high shrinkage yarn and a light interference fiber which is a low shrinkage yarn. Having composite yarn. 8. The optical interference function according to any one of claims 1 to 5, wherein the composite yarn is a covering yarn in which a light shrinkable yarn as a low shrinkage yarn is wound around a high shrinkage yarn. A composite yarn having: 9. A dyed or soaked fiber having an L value of 40 or less is relatively located in a core portion, an optical interference fiber is relatively arranged in a surface layer portion, and both fibers are in a mixed state. A composite yarn having the characteristic optical interference function. 10. The composite yarn having an optical interference function according to claim 9, wherein the color of the dyed or deposited fiber has a complementary color with that of the light interference fiber. 11. The optical interference fiber according to the following (a) to
The composite yarn having an optical interference function according to claim 9, which satisfies the requirement (c). (A) Flatness: 4 to 15 (b) Number of layers: 15 to 120 (c) Elongation (%): 10 to 60 12. A combination of two kinds of polymers having different refractive indices, wherein (a) a dibasic acid component having a sulfonic acid metal base is in a range of 0.3 to 0.3 to a total of dibasic acid components forming a polyester.
10. A combination of a polyester (high refractive index polymer) composed mainly of polyethylene naphthalate copolymerized with 5 mol% and (b) an aliphatic polyamide (low refractive index polymer). 2. The composite yarn having an optical interference function according to item 1. 13. A combination of two kinds of polymers having different refractive indices, wherein (a) a dibasic acid component having a sulfonic acid metal base is in the range of 0.3 to 0.3 per total dibasic acid components forming a polyester.
Polyester mainly composed of polyethylene terephthalate copolymerized at 10 mol% (high refractive index polymer)
The composite yarn having an optical interference function according to any one of claims 1 to 9, which is a combination of (b) a polymethyl methacrylate having an acid value of 3 or more. 14. A combination of two kinds of polymers having different refractive indices: (a) a dibasic acid component having at least one alkyl group in a side chain and / or a glycol component as a copolymerization component, wherein the copolymerization component is 10. A combination of a copolymerized aromatic polyester (high refractive index polymer) copolymerized in an amount of 5 to 30 mol% per all repeating units, and (b) polymethyl methacrylate (low refractive index component). A composite yarn having the optical interference function according to any one of the above. 15. The composite yarn having an optical interference function according to claim 14, wherein the alkyl group is a methyl group. 16. The composite yarn having an optical interference function according to claim 14, wherein the copolymer component is neopentylene glycol. 17. The composite yarn having an optical interference function according to claim 14, wherein the copolymer component is bisphenol A or an ethylene oxide adduct of bisphenol A.