JP2004115954A - Stretchable fancy yarn having antimicrobial property - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a stretchable fancy yarn which has metallic luster, antimicrobial properties and antistatic characteristic, keeps the antimicrobial properties and antistatic characteristic for a long period of time and provides corrosion resistance and low antigenicity. <P>SOLUTION: The stretchable yarn is obtained by cutting a laminate film, in which a metal thin film layer composed of silver or copper exists on at least one side of a plastic film, into a filamentous state to form a flat foil yarn having metallic luster, winding the flat foil yarn on an elastic yarn being a core yarn in a drawn state in fixed length in one direction and winding a press yarn on the wound yarn in the reverse direction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a stretchable design yarn having antibacterial properties, and also relates to a stretchable design yarn having antistatic properties, and further having excellent corrosion resistance and low antigenicity.
[0002]
[Prior art]
For many years, foil yarns such as gold and silver yarns and lame yarns have been considered to be unable to produce stretchable yarns because cracks occur in the foil when stretched, resulting in loss of metallic luster.
After that, a stretchable design yarn in which a foil yarn is wound around an elastic yarn was developed, and the present applicant has already applied for a patent and obtained a patent for the invention relating to the design yarn (see Patent Document 1). It was impossible to impart commercial value antibacterial properties, antistatic properties, corrosion resistance, and low antigenicity to the glossy product of the design yarn.
The term “low antigenicity” as used herein means that the antigenicity that causes skin damage (the property that can be an allergen that is a substance causing allergy) is low.
[0003]
[Patent Document 1]
Japanese Patent No. 2796708
[Problems to be solved by the invention]
The present invention has a metallic luster, has antibacterial properties and antistatic properties, maintains the antibacterial properties and antistatic properties for a long time, and can also impart corrosion resistance and low antigenicity. An object of the present invention is to provide a stretchable design yarn.
[0005]
[Means for Solving the Problems]
Stretchable decorative yarn of the present invention, at least one side of the plastic film, a metal glossy flat foil yarn obtained by cutting a laminate film having a metal thin film layer made of silver or copper into a thread, stretched to a certain length. It is characterized in that it is wound in one direction around an elastic yarn which is a core yarn in a folded state, and a pressing yarn is wound therefrom in an opposite direction.
[0006]
Such a design yarn has not only antibacterial properties but also antistatic properties since a metal thin film layer made of silver or copper is present in the structure of the flat foil thread.
In addition, the holding yarn prevents the flat foil yarn from shifting, so that the elastic yarn and the flat foil yarn do not separate, and since the holding yarn also reinforces the entire stretchable design yarn, the stretchable design yarn of the present invention is stable. It becomes possible to expand and contract.
[0007]
The flat foil yarn used in the present invention may have a so-called one-ply configuration in which a metal thin film layer is formed on one side of a plastic film, or two laminates each having a metal thin film layer formed on a plastic film. This is a so-called two-ply configuration in which the metal thin film layer is bonded inside with an adhesive layer, or a plastic film is bonded to the metal thin film layer side of the laminate in which the metal thin film layer is formed on a plastic film with an adhesive layer. There may be.
In particular, in the two-ply flat foil yarn, since the plastic film exists on both the front and back surfaces of the metal thin film layer, corrosion of the metal thin film layer is prevented, and antibacterial properties and antistatic properties are maintained for a long time. .
[0008]
As the plastic film, various plastic films conventionally used for flat foil yarns, such as a polyethylene terephthalate film, a polyamide film, a polyethylene film and a polypropylene film, can be used.
[0009]
The adhesive layer is formed by a conventionally known coating method, such as a gravure coating method or a reverse coating method, using various resins conventionally used for an adhesive layer of a flat foil yarn such as a polyester resin and a polyurethane resin. it can.
[0010]
The metal thin film layer of the flat foil yarn is made of silver or copper formed on a plastic film by a conventionally known thin film forming method such as vacuum deposition, sputtering, or ion plating.
By using silver or copper for the metal thin film layer, it has antistatic properties as well as antibacterial properties.
[0011]
The flat foil yarn has a so-called anchor coat layer formed of an appropriate resin such as an amino resin, a polyester resin, an epoxy resin, an acrylic resin, or a urethane resin for the purpose of improving the adhesion between the plastic film and the metal thin film. May be. Also, for the purpose of improving corrosion resistance, an amino resin, a polyester resin, an epoxy resin, an acrylic resin, a urethane resin, or the like is provided on the surface of the metal thin film layer opposite to the side on which the plastic film or the anchor coat layer is formed. A so-called top coat layer made of an appropriate resin may be formed.
[0012]
In addition, if an anchor coat layer having an amino resin content of 40 to 3% by weight is formed between the plastic film of the two-ply flat foil yarn and the metal thin film layer, the adhesion between the two is further improved and the elasticity is improved. The design yarn has excellent corrosion resistance that does not corrode easily even if it comes into contact with sweat, alkali, or the like. As a result, antibacterial properties and antistatic properties can be maintained more stably for a long period of time.
[0013]
Further, if a top coat layer having an amino resin content of 40 to 3% by weight is formed on the surface of the metal thin film layer opposite to the side on which the anchor coat layer is formed, only the anchor coat layer is formed. It is more preferable than the case because the corrosion resistance of the stretchable design yarn is further improved.
[0014]
In particular, in a two-ply flat foil yarn, when an anchor coat layer and a top coat layer each having an amino resin content of 40 to 3% by weight are formed and the metal thin film layer is a silver thin film layer, In addition, it becomes a stretchable design yarn having very excellent corrosion resistance, that is, it can withstand severe refining, that is, also has refining resistance.
[0015]
By the way, since the amino resin paint contains a considerable amount of formaldehyde which is generally considered to have high antigenicity, when the amino resin paint is used for forming an anchor coat layer or a top coat layer, As the amino resin content in the anchor coat layer and the top coat layer increases, the amount of formaldehyde eluted from the flat foil yarn increases.
Therefore, by setting the amino resin content of the anchor coat layer and the top coat layer in the two-ply flat foil yarn to 20 to 3% by weight, the corrosion resistance when the amino resin content exceeds 20% is improved. Since the amount of formaldehyde eluted from the anchor coat layer and the top coat layer is suppressed while maintaining the level, the `` Regulations for Enforcement of the Regulations on the Regulation of Household Products Containing Hazardous Substances '' were established to protect consumers from harmful substances. (September 26, 1974, Ministry of Health and Welfare Ordinance No. 34) "(hereinafter abbreviated as Ministry of Health and Welfare Ordinance No. 34). In particular, it is possible to completely clear the strictly defined standards for textile products for infants (absorbance difference of 0.05 or less). Stretchable design yarn Ming also naturally be to clear the above criteria, it becomes having both also corrosion resistance while having excellent low antigenicity.
Therefore, the stretchable decorative yarn of the present invention can be used for textile products for infants and underwear that directly touches the skin.
[0016]
In addition, the flat foil yarn may form a colored layer colored with an appropriate dye or pigment, etc. separately from the anchor coat layer between the plastic film and the metal thin film layer, or the anchor coat layer by coloring the anchor coat layer. May also serve as a colored layer.
In addition, for the purpose of improving antibacterial properties, an antibacterial agent is mixed into the anchor coat layer and the topcoat layer to form an anchorcoat layer and a topcoat layer with antibacterial properties, and the antibacterial agent is mixed into the front and back surfaces of the flat foil yarn. A formed resin layer may be formed.
[0017]
The stretchable design yarn of the present invention, in a state where the elastic yarn is stretched to a certain length, a core yarn obtained by aligning water-soluble yarns, and the flat foil yarn is wound around the core yarn in one direction. The holding thread may be wound in the opposite direction from above.
[0018]
According to the present invention, as described above, since the presser yarn prevents the displacement of the flat foil yarn and also reinforces the entire stretchable design yarn, stable expansion and contraction becomes possible, but the elastic yarn is stretched to a certain length. In a state where the water-soluble yarn is aligned, the core yarn is used as the core yarn, and the flat foil yarn is wound around this core yarn in one direction, and the holding yarn is wound in the opposite direction from above, thereby further expanding and contracting. Becomes stable.
When the water-soluble yarns are aligned, the elastic yarns do not extend beyond the length of the aligned water-soluble yarns. Therefore, the elongation is limited during weaving or knitting, and weaving or knitting can be performed with good workability.
In addition, during dyeing or refining after weaving or knitting, the water-soluble yarn dissolves and drops off. The property can be imparted.
[0019]
The stretchable design yarn of the present invention may be used in the form of a single yarn as it is, or may be used by twisting two or more yarns, and in any form such as a woven fabric, a knitted fabric, a lace, a lily yarn, and the like. Can be used with good elasticity.
Furthermore, the above-mentioned woven cloth, knitted cloth, etc. are towels, tablecloths, pillow covers, underwear, baby clothes, socks, pantyhose, pajamas, aprons, shirts, sweaters, lining of clothes, curtains, rugs, mats, carpets, chair covers. It can be used for various textile products such as car seats, futons, cloths and sheets.
[0020]
As the elastic yarn serving as the core yarn of the stretchable design yarn, any elastic yarn having rubber elasticity can be used, and the material is not particularly limited. For example, nylon wooly yarn, polyurethane elastic yarn, polyester strong twist yarn An elastic yarn such as a natural fiber strong twist yarn can be used.
[0021]
Generally, the thickness of the elastic yarn is preferably about 7 to 1000 denier.
If the thickness is less than 7 denier, the strength is weak, and the yarn breaks easily, and the twisting becomes difficult.
On the other hand, if the thickness is greater than 1000 denier, the strength becomes too strong and the texture becomes poor. It is particularly preferred that it is about 10 to 300 denier.
[0022]
Next, the thickness and width of the flat foil yarn used in the present invention are not particularly limited, but are generally about 3 to 60 μm in thickness and about 0.13 to 10 mm in width for easy handling, and particularly about 9 to 35 μm in thickness. And a width of about 0.15 to 3.3 mm.
If the thickness is less than 3 μm, the flat foil yarn is too thin to easily stretch at the time of twisting. If the thickness is more than 60 μm, the texture becomes too thick and the texture becomes poor.
On the other hand, if the width is less than 0.13 mm, the flat foil yarn is too thin to easily stretch at the time of twisting. If the width is more than 10 mm, it is too wide and difficult to handle, and the texture is poor.
[0023]
Furthermore, the holding yarn wound in the opposite direction from the top of the flat yarn wound around the elastic yarn while it is stretched prevents the flat yarn from shifting and at the same time reinforces the entire stretchable design yarn of the present invention. In order to stabilize expansion and contraction, the yarn is preferably substantially non-stretchable.
The type of fiber used for the holding yarn may be any of natural fiber, semi-synthetic fiber and synthetic fiber, and may be made of short fiber or long fiber.
[0024]
The winding of the flat foil yarn and the winding of the presser yarn can be performed by twisting, that is, twisting.
In the twisting method, it is preferable to wind a flat foil yarn in a state where the elastic yarn is stretched 1.1 to 5.0 times, and it is difficult to twist when the elongation rate of the elastic yarn during twisting is smaller than 1.1 times. On the other hand, if the loop formation of the flat foil yarn is not sufficient, and if it is more than 5.0 times, the elongation is too large, it is also difficult to twist, and the loop of the flat foil yarn becomes too large and it is easy to catch. , Becomes difficult to handle.
In the case where the water-soluble yarn is used by being aligned with the elastic yarn, the elastic yarn is stretched about 1.5 to 5.0 times, the water-soluble yarn is aligned, and the flat foil yarn is laid on top of the water-soluble yarn. Good to wrap.
In any case, the stretched state of the elastic yarn at the time of twisting is more preferably about 1.5 to 3.5 times the elongation.
[0025]
The number of windings (twisting number) of the flat foil yarn around the elastic yarn varies depending on the stretched state of the elastic yarn and the thickness of the elastic yarn or the flat foil yarn, but is usually 50 to 1500 T / M in a state where the elastic yarn is stretched. It is preferred that
When this rotation is less than 50 T / M or more than 1500 T / M, the number of loops formed by the flat foil yarn is too small or too large, and it is difficult for the loops to appear on average. It is difficult to obtain a textured product.
A particularly preferred number of twists is 100 to 600 T / M.
[0026]
Next, the number of windings (twisting number) of the presser yarn wound in the opposite direction to the flat foil yarn from above the flat foil yarn in a state where the elastic yarn is stretched should be 100 to 2000 T / M. preferable.
If it is less than 100 T / M, the whole of the stretchable design yarn is insufficiently reinforced, and the flat foil yarn is not sufficiently prevented from being displaced. The flat foil yarn is not fixed, easily moves in the longitudinal direction, and has a good texture. I can't get it.
Conversely, if it is more than 2000 T / M, the number of loops of the presser thread is too large, so that it is easy to move in the longitudinal direction without fixing, and as a result, it does not serve as reinforcement and it is difficult to obtain a good texture. A particularly preferred number of twists is 200 to 600 T / M.
In addition, the number of twists of the presser yarn wound from above the flat foil yarn is usually equal to or more than the number of twists of the flat foil yarn, for example, it is preferably about 1 to 13 times the number of twists of the flat foil yarn, and particularly preferably 1 to 1. It is preferably about five times.
[0027]
The thickness of the presser yarn wound around the elastic yarn is preferably about 0.5 to 15 times the thickness of the elastic yarn in the stretched state.
[0028]
The water-soluble yarn used in line with the elastic yarn is preferably a water-soluble filament yarn, and a water-soluble vinylon yarn or the like can be used.
In order to limit the elasticity of the elastic yarn, the thickness is preferably equal to or more than the thickness of the elastic yarn in the stretched state, about 1 to 8 times, particularly about 1 to 6 times.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in more detail with reference to examples.
Production of flat foil yarn On one side of a transparent polyethylene terephthalate film having a thickness of 12 μm, a colored layer having a thickness of 0.8 μm is formed by mixing a yellow dye in a resin of 95% by weight of a polyester resin and 5% by weight of a melamine resin, and then forming a polyester resin. An anchor coat layer having a thickness of 0.8 μm comprising 95% by weight and 5% by weight of a melamine resin is formed, and a 60 nm-thick silver thin film layer is further formed on the anchor coat layer by vacuum evaporation. A 0.8 μm thick top coat layer made of the same resin as the anchor coat layer was formed to obtain a laminate.
Next, a transparent polyethylene terephthalate film having a thickness of 0.8 μm formed on a transparent polyethylene terephthalate film having a thickness of 12 μm was formed on the top coat layer of the above-mentioned laminate, with the coloring layer being on the inside. The laminate bonded with a 5 μm polyester resin adhesive layer was slit to obtain a flat foil yarn having a width of 0.3 mm and a thickness of about 28 μm, both front and back surfaces of which were golden.
B. On one surface of a transparent polyethylene terephthalate film having a thickness of 9 μm, an anchor coat layer having a thickness of 0.8 μm comprising 90% by weight of a polyester resin and 10% by weight of a melamine resin is formed. After forming a 60 nm silver thin film layer, a 1.0 μm thick white top coat layer in which titanium oxide powder is mixed into a resin of 90% by weight of a polyester resin and 10% by weight of a melamine resin is formed on the silver thin film layer. A laminate was obtained.
Next, two sheets of the above-mentioned laminated body were prepared, and the two sheets were bonded together with a 1.5 μm-thick polyester resin adhesive layer with the top coat layer on the inside. A flat foil having a silver color of about 23 μm on both sides was obtained.
C. A 1.0 μm thick anchor coat layer composed of 80% by weight of a polyester resin and 20% by weight of an acrylic resin is formed on one side of a transparent polyethylene terephthalate film having a thickness of 9 μm. A laminate having a 60 nm thick copper thin film layer was obtained.
Next, two sheets of the above laminated body were prepared, and the two sheets were bonded together with a 1.5 μm-thick polyester resin adhesive layer with the copper thin film layer on the inner side, and slit. A flat foil yarn having a copper color on both the front and back sides having a thickness of about 22 μm was obtained.
D. On the anchor coat layer, a silver flat foil yarn having both front and back surfaces was obtained in the same manner as the flat foil yarn of B except that a 60 nm thick aluminum thin film layer was formed by vacuum evaporation instead of the silver thin film layer. Was.
[0030]
Embodiment 1
In a state where a 70-denier elastic yarn (polyurethane yarn from Toray DuPont: Lycra) is stretched 2.5 times (the thickness of the yarn in the stretched state is about 28 denier), the flat foil yarn obtained in the above A is subjected to 200T. / M twisted to the right, and a 50-denier nylon yarn was twisted leftward at a twist of 400 T / M.
The stretched state of the elastic yarn was released to obtain a stretchable design yarn of the present invention in which a loop of a gold flat foil yarn was formed uniformly over the entire surface and was highly stretchable.
[0031]
Embodiment 2
Except for using the flat foil obtained in B above as the flat foil, in the same manner as in Example 1, the stretchable design yarn of the present invention in which the loops of the silver flat foil were uniformly formed throughout. Got.
[0032]
Embodiment 3
The stretchable design of the present invention in which the loops of the copper-colored flat foil yarn were uniformly formed in the same manner as in Example 1 except that the flat foil yarn obtained in the above C was used as the flat foil yarn. Yarn was obtained.
[0033]
[Comparative Example 1]
Except for using the flat foil obtained in the above D as the flat foil, a stretchable design yarn in which the loop of the silver flat foil was uniformly formed on the whole was obtained in the same manner as in Example 1. .
[0034]
Embodiment 4
The stretchable design yarns obtained in Examples 1 to 3 were produced into a two-needle liliyaan A and a four-needle liliyaan B, respectively.
The lily yarn A and the lily yarn B using the stretchable design yarn obtained in Example 1 are golden, the lily yarn A and the lily yarn B using the stretchable design yarn obtained in Example 2 are silver, and they are obtained in Example 3. The lily yarn A and the lily yarn B using the stretchable design yarn each exhibited a copper-colored metallic luster, and all the above-mentioned lily yarns A and B had elasticity.
[0035]
Embodiment 5
A 20 denier elastic yarn (polyurethane yarn made by Asahi Kasei Corporation: Leica) is stretched 3.0 times (the thickness of the yarn in the stretched state is about 7 deniers), and a 30 denier water-soluble vinylon yarn (Nichibi) is added. Co., Ltd .: Solblon), which is used as a core yarn, and the flat foil yarn obtained in the above B is wound thereon with a twist number of about 600 T / M, and then a 15-denier nylon yarn is turned upside down to 600 T / M. / M twists to obtain a stretchable design yarn of the present invention.
[0036]
Embodiment 6
When the stretchable decorative yarn obtained in Example 5 was woven, the stretch of the elastic yarn was restricted by the aligned water-soluble vinylon yarn, so that the fabric could be woven with good workability in the same manner as ordinary yarn.
After weaving, refining and high-pressure dyeing revealed that the water-soluble vinylon yarn was dissolved and removed in the dye bath, and the elasticity of the elastic yarn was restored. Thus, a beautifully dyed elastic woven fabric was obtained.
The woven fabric did not cause any corrosion of the silver thin film layer even by refining, was extremely excellent in corrosion resistance, and had refining resistance.
[0037]
Embodiment 7
When the stretchable decorative yarn obtained in Example 5 was knitted by a weft knitting machine, the elongation of the elastic yarn was restricted by the aligned water-soluble vinylon yarns, so that a good-quality knit fabric was obtained without any problem. Was completed.
When the knitted fabric was subjected to high-pressure dyeing, the water-soluble vinylon yarn was dissolved and removed in a dye bath, and the elasticity of the elastic yarn was restored. The obtained elastic knitted fabric had a strong so-called kickback property.
[0038]
Embodiment 8
When a car seat was manufactured using the knitted fabric obtained in Example 7, almost no static electricity was generated at the time of getting on and off the car, and the car seat was excellent in antistatic property.
[0039]
1. Antimicrobial test (evaluation sample) 0.4 g of the stretchable design yarn of the present invention obtained in Examples 1 to 3 and the stretchable design yarn obtained in Comparative Example 1 were prepared as samples.
(Evaluation method) SEK microbial counting method: After sterilizing the sample with autoclave, inoculate each sample with 0.2 ml of a leukomycobacterial solution adjusted to about 10 ⁵ CFU / ml with a 1/20 nutrient medium. After storage at 37 ° C. for 18 hours, the number of surviving bacteria was measured.
(Evaluation Results) The stretchable design yarn of the present invention obtained in Examples 1 to 3 and 5 in which the metal thin film layer of the flat foil yarn is formed of the silver or copper thin film layer, has a viable cell count before culturing. It was reduced to 1/10 or less of the number and had excellent antibacterial properties.
On the other hand, with respect to the stretchable design yarn obtained in Comparative Example 1 in which the metal thin film layer of the flat foil yarn was formed of the aluminum thin film layer, the number of surviving bacteria did not change at all from the number of bacteria before culturing, and the antibacterial property was not changed. Did not have.
[0040]
2. Formaldehyde test (evaluation sample) 2.5 g of the stretchable design yarn of the present invention obtained in Examples 1, 2, and 5 was prepared and used as a sample.
(Evaluation method) Test method for textile products for infants specified in Ministry of Health and Welfare Ordinance No. 34.
(Evaluation Results) All of the stretchable design yarns had a difference in absorbance of 0.01, satisfying the standard for textile products for infants (absorbance difference of 0.05 or less).
[0041]
【The invention's effect】
In the present invention, at least one side of a plastic film, a metallic glossy flat foil yarn obtained by cutting a laminate film having a metal thin film layer made of silver or copper into a thread shape is stretched to a certain length. The elastic yarn is wound in one direction, and the presser yarn is wound in the opposite direction from above, so that it has good antibacterial properties, and also has a metallic luster, elasticity, and antistatic properties. Can be obtained.
In addition, in the case where the core yarn is made of a combination of elastic yarns and water-soluble yarns, a woven or knitted fabric can be obtained more stably with a normal loom or knitting machine. By dissolving and removing the yarn, it is possible to obtain a designable elastic fabric having excellent antibacterial properties.
[0042]
When the flat foil yarn used for the stretchable design yarn has a two-ply configuration, since the plastic film exists on both front and back surfaces of the metal thin film layer of the flat foil yarn, corrosion of the metal thin film layer is prevented, The anti-bacterial property and the anti-static property can be maintained for a long time.
[0043]
Furthermore, if an anchor coat layer having an amino resin content of 40 to 3% by weight is formed between the plastic film of the two-ply flat foil yarn and the metal thin film layer, the adhesion between the two is further improved and the elasticity is improved. The design yarn has excellent corrosion resistance that does not corrode easily even if it comes into contact with sweat, alkali, or the like. As a result, antibacterial properties and antistatic properties can be maintained more stably for a long period of time.
[0044]
Further, if a top coat layer having an amino resin content of 40 to 3% by weight is formed on the surface of the metal thin film layer opposite to the side on which the anchor coat layer is formed, only the anchor coat layer is formed. It is more preferable than the case because the corrosion resistance of the stretchable design yarn is further improved.
In particular, when the metal thin film layer is a silver thin film layer at this time, it also has refining resistance.
[0045]
When the amino resin content of the anchor coat layer or the top coat layer of the two-ply flat foil yarn is 20 to 3% by weight, the corrosion resistance when the amino resin content exceeds 20% is reduced. In addition, the amount of formaldehyde eluted from the anchor coat layer and the top coat layer is suppressed, so that the standards for the textile products for infants (absorbance difference (0.05 or less), the stretchable design yarn of the present invention using such a flat foil yarn naturally satisfies the above criterion, and has excellent low antigenicity and resistance to resistance. It also has corrosiveness.
Therefore, the stretchable decorative yarn of the present invention can be used for textile products for infants and underwear that directly touches the skin.
[0046]
The stretchable design yarn of the present invention, in a state where the elastic yarn is stretched to a certain length, a core yarn obtained by aligning water-soluble yarns, and the flat foil yarn is wound around the core yarn in one direction. The holding thread may be wound in the opposite direction from above.
When the water-soluble yarns are aligned, the elastic yarns do not extend beyond the length of the aligned water-soluble yarns. Therefore, the elongation is limited during weaving or knitting, and weaving or knitting can be performed with good workability.
In addition, during dyeing or refining after weaving or knitting, the water-soluble yarn dissolves and drops off. The property can be imparted.

Claims (7)

A metallic glossy flat foil yarn obtained by cutting a laminate film having a metal thin film layer made of silver or copper on at least one surface of a plastic film into an elastic yarn which is a core yarn stretched to a certain length. Is stretched in one direction, and a presser yarn is wound in the opposite direction from above, the stretchable design yarn having antibacterial properties. The stretchable decorative yarn according to claim 1, wherein the flat foil yarn has a plastic film on both front and back surfaces, and a metal thin film layer made of silver or copper exists between these films. The stretchable decorative yarn according to claim 2, wherein an anchor coat layer having an amino resin content of 40 to 3% by weight is formed between the plastic film and the metal thin film layer. The stretchable decorative yarn according to claim 3, wherein a top coat layer having an amino resin content of 40 to 3% by weight is formed on the surface of the metal thin film layer opposite to the side on which the anchor coat layer is formed. The stretchable decorative yarn according to claim 4, wherein the metal thin film layer is a silver thin film layer. The stretchable decorative yarn according to any one of claims 3 to 5, wherein the amino resin content is 20 to 3% by weight. The stretchable design yarn according to any one of claims 1 to 6, wherein a core yarn is obtained by stretching water-soluble yarns in a state where the elastic yarns are stretched to a predetermined length.