JP2005154909A - Wound body of polyurethane elastic yarn for paper diaper and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wound body of a polyurethane elastic yarn for a disposable paper diaper, having a good adhesion of a nonwoven fabric with the elastic yarn for the paper diaper in the paper diaper product and a good processing property in the production of the paper diaper, capable of discriminating the polyurethan elastic yarn from the upper direction of the nonwoven fabric and without having dyeing unevenness in the cheese wound body of the polyurethane elastic yarn for the paper diaper. <P>SOLUTION: This wound body of the polyurethane elastic yarn for the paper diaper is characterized by having ≥20 and ≤80 color difference ΔE of the yarn and wound in a state of containing or attaching a lipophilic dye. The method for producing the wound body of the polyurethane elastic yarn for the paper diaper is provided by dissolving or dispersing the lipophilic dye in a fiber-treating agent containing a polydimethylsiloxane and attaching it by ≥2.5 % and ≤5.0 % to the polyurethane elastic yarn and winding. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a polyurethane elastic yarn used for the purpose of imparting stretch properties to a gathered portion or a crotch portion of a disposable paper diaper, and more particularly, to a colored polyurethane elastic bobbin for paper diapers and a method for producing the same. Is.

With the recent trend of disposable diapers, it is common practice to form gathers using polyurethane elastic yarn or rubber yarn on the waist and crotch for the purpose of enhancing wear and preventing leakage. Yes. As a method for supplying elastic yarn used for gathering paper diapers, an elastic yarn wound body is placed on a driving roller, and the elastic yarn is pulled out while rotating the wound yarn body in the direction of unwinding the elastic yarn, A method of supplying to a diaper making machine is used. As such a polyurethane elastic bobbin for paper diapers, for example, Patent Document 1 proposes a polyurethane elastic bobbin for paper diapers that is excellent in adhesiveness and process performance in the manufacturing process of paper diapers.
With the increase in added value demanded by consumers in recent years, disposable paper diaper products have been diversified, and various functions have been demanded as polyurethane elastic bobbin for paper diapers. In particular, the colored polyurethane elastic yarn for paper diapers that makes it possible to identify polyurethane elastic yarn even from the top of non-woven fabrics can be used for checking the quality of products when making paper diapers, and for positioning when using paper diapers, etc. There was a strong request. For example, Patent Document 2 proposes using an elastic thread colored on a disposable diaper to align the urine pad.

  Usually, as a method for producing a colored polyurethane elastic fiber, a method of mixing and spinning various dyes, pigments or inorganic compounds such as carbon black and titanium oxide in a raw material polymer is known. For example, Patent Document 3 proposes a polyurethane elastic yarn colored by adding an inorganic pigment having an average particle diameter of 10 μm or less. Patent Document 4 also proposes to make a colored polyurethane by adding a pigment. However, in any production method, a pigment is added in the polymerization step, and there are problems such as an increase in defects in the yarn and a decrease in physical properties such as breaking strength and elongation. In addition, even if it is possible to produce one color, changing the amount of dye or pigment to change the type of color or the color intensity will increase the liquid loss and the cost of yarn production. However, the production of polyurethane elastic bobbin with various colors is difficult. In addition, in the process of producing polyurethane elastic yarn, a fiber treatment agent is usually attached to the surface for the purpose of improving the unwinding property. However, the fiber made of a polyurethane polymer to which a pigment is added is compatible with the fiber treatment agent. However, since the agent is difficult to adhere, there is a problem that the amount of adhesion and adhesion spots are likely to occur. Decrease in adhesion amount and adhesion spots are likely to cause thread breakage in the paper diaper manufacturing process, so increasing the adhesion amount as a countermeasure reduces the adhesion to the nonwoven fabric that forms the gathered part of the paper diaper, There was a problem of non-uniform shapes.

As a method for producing a colored polyurethane elastic yarn other than adding a pigment during polymerization, a so-called cheese dyeing method for dyeing an elastic bobbin (cheese) itself is performed. Interlayer color difference variation is likely to occur, and the fiber treatment agent adhering to the elastic yarn is removed by dyeing, so when supplying it to the paper diaper process, yarn breakage due to unwinding failure, friction with the guide, etc. Since the processability deteriorates, such as being easily generated, there is a problem that it cannot be used in the paper diaper manufacturing process.
Due to the above problems, polyurethane elastic yarns for paper diapers, which are excellent in processability and free from color spots and colored in various colors, have not been obtained.
Japanese Patent Publication No. 5-50429 Japanese Patent Laid-Open No. 11-347065 JP 58-186609 A Japanese Patent Publication No. 60-44406

The present invention has good adhesiveness between the nonwoven fabric and the elastic yarn for paper diapers in the paper diaper product and the processability in the paper diaper manufacturing process, and can identify the polyurethane elastic yarn for paper diaper from above the nonwoven fabric, and It is an object of the present invention to obtain a polyurethane elastic bobbin for disposable paper diapers that is free from unevenness in the polyurethane elastic bobbin for paper diapers and spots of fiber treatment agents.
In addition, in order to solve the problems of the conventional method for producing colored polyurethane elastic yarns and to cope with the diversification of disposable paper diaper products, many types of colored polyurethane elastic yarns were used in the production of polyurethane elastic yarns. It aims at providing the manufacturing method which provides without the influence of the contamination of a stock solution process, and a raw material physical property.

The present invention is as follows.
1. A polyurethane elastic bobbin for paper diapers, wherein the yarn has a color difference ΔE of 20 or more and 80 or less, and is wound in a state of containing or adhering a lipophilic dye.
2. 2. The polyurethane elastic bobbin for paper diapers according to 1 above, wherein the color difference variation in the bobbin is 2 or less.
3. 3. The polyurethane elastic bobbin for paper diapers according to 1 or 2 above, wherein the fiber treatment agent containing polydimethylsiloxane as a main component is wound in a state of containing or adhering to 0.5 to 10.0 wt%. body.
4). 4. The polyurethane elastic bobbin for paper diapers according to any one of 1 to 3 above, wherein the yarn fineness is 155 to 3000 dtex.
5). The polyurethane for paper diapers according to any one of 1 to 4 above, wherein the difference in ΔE indicating the fastness before and after being immersed in physiological saline at 40 ° C. for 24 hours is 1.0 or less. Elastic bobbin.
6). The polyurethane elastic bobbin for paper diapers as described in any one of 1 to 5 above, wherein the lipophilic dye is at least one of an azo type or an anthraquinone type.
7). 7. The polyurethane elastic bobbin for paper diapers according to any one of 1 to 6 above, wherein the polyurethane elastic yarn contains at least a copolymer diol unit having a unit represented by the following (I).

(Wherein R ₁ is a C ₁ -C ₃ alkyl group, R ₂ is H or a C ₁ -C ₃ alkyl group, m and n are integers of 1 to 3)
8). A fiber treatment agent containing 10 wt% or more of polydimethylsiloxane and 0.1 to 10 wt% of a lipophilic dye dissolved or dispersed is attached to 2.5 to 5.0 wt% of a polyurethane elastic yarn and wound. The manufacturing method of the polyurethane elastic bobbin for paper diapers in any one of said 1-7.

  The present invention provides a polyurethane elastic bobbin that can be distinguished from the nonwoven fabric without losing the processability and adhesiveness of the paper diaper manufacturing process, and has sufficient fastness to withstand practical use and does not discolor. provide. Further, it is possible to produce a polyurethane elastic bobbin colored in various colors without polluting the polyurethane elastic yarn production process and without affecting the physical properties of the polyurethane elastic yarn.

Hereinafter, the present invention will be described in detail.
The present inventor has found that the polyurethane elastic yarn can be easily identified even from the top of the nonwoven fabric because the color difference ΔE when the polyurethane elastic yarn is card-wrapped is 20 or more. Here, the color difference ΔE indicates the color when there is no black light as a zero point, and indicates the difference between the values of white, black, red, green, yellow, and blue colors and the reference white plate, It is the value measured by the method to be described later.
Further, in order to maintain the quality in the paper diaper product, the change in the color difference ΔE in the polyurethane elastic bobbin for paper diapers is preferably 2 or less, but when the color difference ΔE is 80 or more, The difference in color difference increases, and the quality of paper diaper products cannot be maintained. If ΔE is less than 20, the distinguishability of the polyurethane elastic yarn is lowered, which is not preferable. In order to prevent color fading, color bleeding, etc. when using paper diapers, it is preferable that the change in color difference ΔE before and after being immersed in physiological saline at 40 ° C. for 24 hours is 1 or less.

  The polyurethane elastic bobbin of the present invention is characterized in that it is wound in a state where a lipophilic dye is contained or adhered. By using an oleophilic dye, the process performance at the time of manufacturing for paper diapers can be maintained at the same level as that of a conventional uncolored polyurethane elastic yarn. Moreover, it can use suitably in the polyurethane elastic bobbin thread manufacturing method mentioned later. There are many types of lipophilic dyes, such as dyes using oil-based pigments and those obtained by solubilizing originally water-soluble dyes, such as azo-based and anthraquinone-based oil-soluble metal-containing dyes, turmeric There are natural pigments such as pigments, and azo or anthraquinone oil-soluble metal-containing dyes are desirable from the viewpoint of dispersibility of the fiber treatment agent and the lipophilic dye. The polyurethane elastic bobbin for hair diapers of the present invention containing or adhering a lipophilic dye is excellent in dyeability and dyeing fastness, and can be preferably used for paper diaper applications.

  In addition, it has been found that the processability in the colored polyurethane elastic yarn paper diaper manufacturing process can be maintained by containing or adhering a fiber treatment agent and a lipophilic dye that improve the processability of the diaper manufacturing process. It was. Examples of such a fiber treatment agent include a mixture of polydimethylsiloxane and mineral oil. In the present invention, a fiber treatment agent containing polydimethylsiloxane as a main component contains or adheres a lipophilic dye. It is preferable that 0.1 to 10 wt% of the polyurethane elastic bobbin is contained or attached. If it is less than 0.1 wt%, the processability in the paper diaper manufacturing process may be deteriorated, and if it exceeds 10 wt%, the adhesiveness with the nonwoven fabric constituting the paper diapergather may be deteriorated. More preferably, it is 2.5-5.0 wt%.

  In the present invention, the polyurethane elastic yarn has an isocyanate-terminated prepolymer prepared with a substantially linear polymer diol, a chain extender having a polyfunctional active hydrogen atom, and a terminal having a monofunctional active hydrogen atom. Any polymer can be used as long as it is obtained by dry spinning, wet spinning or melt spinning a polyurethane polymer having a urethane group in the molecule, obtained by reacting a blocking agent in one or more stages. When the diol contains a copolymerized diol having a unit represented by the following formula (I), it is preferable because the color difference ΔE is improved by further improving the stability of the dye to the polyurethane elastic yarn.

(Wherein R ₁ is a C ₁ -C ₃ alkyl group, R ₂ is H or a C ₁ -C ₃ alkyl group, m and n are integers of 1 to 3)
Examples of such a copolymer diol include a copolymer of tetrahydrofuran and neopentyl glycol. Specifically, a copolymer diol of tetrahydrofuran and neopentyl glycol is preferably 15 to 15 mol%.

The fineness of the polyurethane elastic yarn of the present invention is preferably 155 to 3000 dtex for paper diapers. More preferably, it is 310-2500 dtex. In addition, the above-mentioned polyurethane polymer may optionally include an organic or inorganic compounding agent having a specific chemical structure used in known polyurethane polymer compositions, such as benzophenone compounds, benzotriazole compounds, binders. UV absorbers such as doamine compounds, antioxidants such as binderd phenol compounds, inorganic fine particles such as barium sulfate, magnesium oxide, magnesium silicate, calcium silicate, zinc oxide, hydrotalcite, magnesium stearate, An anti-adhesive agent such as calcium stearate, polytetrafluoroethylene, and organopolysiloxane can be appropriately blended.
The winding amount of the polyurethane elastic bobbin of the present invention is not particularly limited as long as it can be used in the paper diaper manufacturing process. Usually, a wound body having a winding amount of about 1.0 to 5.0 kg is often used.

The present inventor attaches a fiber treatment agent in which a lipophilic dye is dispersed or dissolved in a fiber treatment agent application step during the production of polyurethane elastic yarn to a polyurethane elastic bobbin for diapers having the above-described characteristics. It has been found that it is possible to produce colored polyurethane elastic yarns for diapers that have sufficient fastness to withstand practical use.
In order to produce the colored polyurethane elastic bobbin of the present invention, at least 0.1 wt% or more of a lipophilic dye is dispersed or dissolved in a fiber treatment agent containing at least 10 wt% or more of polydimethylsiloxane. Can be suitably obtained by adhering at the time of polyurethane elastic yarn production. When the lipophilic dye is dispersed or dissolved in an amount of 10 wt% or more, a colored polyurethane elastic bobbin with a color difference ΔE of 80 or more can be produced. However, the lipophilic dye easily settles in the fiber treatment agent, This is not desirable because the color difference variation at the same time increases and the fastness to dyeing deteriorates, causing problems in the quality of paper diaper products.

As the fiber treatment agent application step for polyurethane elastic yarn, generally, the polyurethane elastic yarn winding step as shown in FIG. 1 is applied using a nozzle oiling method or a roll rotating in a bath containing the fiber treatment agent. The nozzle oiling system can control the fiber treatment agent adhesion amount accurately with a gear pump or the like, and can reduce dyeing spots. Therefore, it is preferable.
As a method of dissolving and dispersing the dye when preparing the fiber treating agent containing the dye, if dissolved, by heating and stirring, etc., if dispersed, homomixer dispersion, ultrasonic disperser, etc. It is possible to make adjustments using a method generally used for dispersion. In order to prevent clogging at the tip of the nozzle oiling, it is preferable to remove aggregates with a filter or the like.

  By confirming the color difference ΔE, the polyurethane elastic bobbin for paper diapers obtained by the above production method can easily find defective threads such as fiber treatment agent adhesion spots, non-adhering yarns, Yarn breakage in the paper diaper manufacturing process can be suppressed, and its processability is equivalent to an uncolored elastic thread for paper diapers. In addition, since the raw solution process is not involved, there is no contamination of the raw solution process and there is no influence on the physical properties of the raw yarn, and many types of colored polyurethane elastic yarns for paper diapers can be produced.

Hereinafter, the present invention will be described in more detail with reference to examples. Measurement methods, evaluation methods, etc. are as follows.
<Color difference evaluation method>
The outermost layer portion of the produced polyurethane elastic yarn was subjected to a winding-side pitch of 0.2 mm (feed: 25 m / min), winding of 20 m / min, and lap winding using a card winding winder (Asano Machinery Manufacturing Co., Ltd.). A sample for color difference measurement is prepared by winding a card with a winding width of 25 mm on a transparent acrylic plate having a thickness of 3 mm and a side of 35 mm × 45 mm. Next, using a simultaneous photometric spectroscopic color difference meter SQ-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.), after adjusting the zero point with the zero point adjustment cap and adjusting the standard value to the standard value with a standard white plate, card winding The sample is placed horizontally on the reflection measurement sample stage, sealed with a zero-point adjustment cap from the top to prevent other colors from entering, and the difference between the standard white plate and the sample color value is measured. ΔE was calculated from the following formula.

<Calculation method of color difference ΔE>
ΔE = [(ΔL) ² + (Δa) ² + (Δb) ² ] ^0.5
ΔL indicates the difference between the value of the monochrome color and the value of the white plate.
Δa indicates the difference between the red-green color value and the white plate value.
Δb indicates the difference between the value of yellowish blue color and this value of the white plate.

<Measurement method of color difference variation>
Measure the color difference ΔE at three points of the outermost layer (100 wt%), outer layer (50 wt%), and inner layer (10 wt%) in the produced polyurethane elastic bobbin body 1 cheese, and the maximum and minimum values Let the color differences ΔE be ΔE _MAX and ΔE _MIN , respectively. The color difference variation in the polyurethane elastic bobbin was taken as the difference from ΔE _MAX and ΔE _MIN, and the value was determined from the following equation.
Color difference variation = ΔE _MAX -ΔE _MIN

<Fastness evaluation method>
The color ΔE of the polyurethane elastic yarn wound on the card is set to ΔE ₁ . Next, this carded sample is immersed in 500 cc physiological saline heated to 40 ° C. in a 1 L beaker for 24 hours, and then dried in a 60 ° C. constant temperature bath for 3 hours. The color difference Delta] E and Delta] E _2. The fastness when using disposable paper diapers was determined as the difference between ΔE ₁ and ΔE ₂ and the value was obtained from the following equation.
Fastness = ΔE ₁ −ΔE ₂

<Identification evaluation method for paper diaper products>
Polyurethane elastic yarn was fed from the wound body at a feed rate of 20 m / min and supplied to a paper diaper manufacturing machine while being stretched 3 times to produce a gathered portion with a nonwoven fabric. About the gathered part of the completed paper diaper, it was judged visually whether a color could be distinguished from the nonwoven fabric.
○: Good △; Difficult to identify immediately ×: Almost impossible to identify

<Processability of paper diaper manufacturing process>
The number of yarn breaks when 1000 m of polyurethane elastic yarn was fed to the paper diaper making machine was measured.
<Adhesiveness with non-woven fabric>
The gathered part of the paper diaper obtained under the above conditions is pasted on the plate in a state where the gathered part is completely pulled until there is no sagging of the nonwoven fabric. Mark both ends of the nonwoven fabric with a polyurethane elastic yarn bonded with a width of 20 cm. As shown in FIG. 2, one end is cut and left in a constant temperature bath at 40 ° C. for 6 hours, and then the moving distance of the polyurethane elastic yarn cutting portion from the uncut cloth is measured. Judged by.
○: within 5 cm ×: longer than 5 cm

[Examples 1 to 4, Comparative Examples 1 to 5]
2200 g of polyoxytetramethylene glycol having a number average molecular weight of 1800 is dissolved in 1400 g of dimethylacetamide and reacted with 480 g of 4,4′-diphenylmethane diisocyanate under stirring in a dry nitrogen atmosphere at 50 ° C. for 2 hours. A polyurethane prepolymer solution was obtained. This was cooled in a water bath at 15 ° C. and dissolved in 1900 g of dimethylacetamide to dilute the polyurethane prepolymer solution. On the other hand, 40.28 g of ethylenediamine and 5.82 g of diethylamine were dissolved in 2144 g of dimethylacetamide and added to the polyurethane prepolymer solution to obtain a polyurethane solution having a concentration of 33.8 wt% and a viscosity of 4500 poise at 30 ° C.

Table 1 shows the amount of red azo lipophilic dye RED RR or Blue 2N (both manufactured by Orient Chemical Co., Ltd.) in a fiber treatment agent adjusted at a component ratio of 30 wt% mineral oil and 70 wt% dimethylpolysiloxane. And a fiber treatment agent in which the dye was uniformly dispersed was prepared by stirring for 2 hours using a homomixer. In Comparative Example 5, a fiber treatment agent in which no dye was dispersed was used.
Using this polyurethane solution and the fiber treatment agent, spinning is performed by a normal dry spinning method, and in the fiber treatment agent application step shown in FIG. 1 when winding the polyurethane elastic yarn, the fiber treatment agent temperature is constant at 30 ° C. and dry air. While bubbling, a predetermined amount of the fiber treatment agent in which the dye is dispersed is sent out from the fiber treatment bath by a gear pump, and is attached to the polyurethane elastic yarn and wound up. The fineness is 620 dtex, and the fiber treatment agent adhesion amount is 3.0 wt%. A polyurethane elastic bobbin was prepared (wound amount 3.0 kg). Here, the nozzle diameter of the nozzle oiling was 0.5 mm in order to prevent adhesion of dyes and the like.

  Color adjustment ΔE of the obtained polyurethane elastic yarn, fastness, identification with paper diaper products, processability of paper diaper manufacturing process, determination of adhesion to non-woven fabric, adjustment amount of dye of the example to fiber treatment agent Of 0.1 wt% or more, the color difference ΔE becomes 20 or more, and a colored polyurethane elastic yarn having a fastness that can be distinguished from the nonwoven fabric and can be sufficiently practically obtained is obtained. The processability in the paper diaper manufacturing process was also good.

[Examples 5, 6, 7 and Comparative Example 6]
A polyurethane elastic bobbin having the same fiber treatment agent prepared in Example 2 as the same polymer and the same fineness and a fiber treatment agent adhesion amount of 2.5 wt%, 5 wt%, and 7.0 wt% was produced. In addition, as Comparative Example 6, a polyurethane elastic bobbin body not provided with a fiber treatment agent was produced. Looking at the color difference ΔE of the obtained polyurethane elastic yarn, fastness, identification with paper diaper products, processability of the paper diaper manufacturing process, and adhesion to the nonwoven fabric, if the amount of fiber treatment agent attached is too much, It can be seen that the adhesiveness tends to decrease, and if the fiber treatment agent is not attached, yarn breakage in the paper diaper manufacturing process increases.

[Examples 8 and 9]
In Example 1, instead of polyoxytetramethylene glycol, a copolymer diol of tetrahydrofuran and neopentyl glycol 10 mol% was used, except that a polymer was prepared under the same conditions as in Example 1, and ordinary dry spinning was performed. A polyurethane elastic yarn having 3% by weight of a fiber treating agent adjusted to the amount shown in Table 1 with the same fineness as in Example 1 was prepared (amount of winding: 3.0 kg). The color difference of the obtained polyurethane elastic yarn, fastness, identification with a paper diaper product, the processability of the paper diaper manufacturing process, compared with Examples 1-2, by using the copolymer diol shown in Formula 1, It can be seen that the color difference ΔE, the color difference variation, and the fastness are better.

[Comparative Example 7]
A commercially available colored wound body was obtained. It was considered to be due to cheese dyeing, and the fiber treatment agent was not attached. Moreover, the color difference variation was large, and the processability of the paper diaper manufacturing process was poor.

[Comparative Example 8]
2.0% of a commercially available acid dye was dispersed in a fiber treatment agent adjusted with a component ratio of 30 wt% mineral oil and 70 wt% dimethylpolysiloxane, but a large amount of undissolved material was uniformly dispersed in the fiber treatment agent. Since the prepared fiber treatment agent cannot be adjusted, the produced yarn provided with 3 wt% of the fiber treatment agent adhesion amount by the same method as in Example 2 has a large variation in color difference and partly due to uneven adhesion of the treatment agent. Sex deteriorated.

[Comparative Examples 9 and 10]
A commercially available carbon black was uniformly dispersed in dimethylacetamide using a homomixer, and then a polyurethane solution in which 5% by weight of carbon black solid content was added to the polymer solid content in the polyurethane solution of Example 1 was added to a normal polyurethane solution. A polyurethane elastic yarn was prepared by dry spinning and having a fineness similar to that of Example 1 and 3 wt% of a fiber treatment agent adjusted with a component ratio of 30 wt% mineral oil and 70 wt% dimethylpolysiloxane (wound amount 3.0 kg). However, there was a large variation in color difference due to insufficient replacement of piping in the stock solution process, and the processability in the paper diaper manufacturing process was poor. Moreover, by increasing the fiber treatment agent application amount to 15 wt%, the processability in the paper diaper manufacturing process was improved, but the adhesiveness with the nonwoven fabric was deteriorated.

  The present invention provides a polyurethane elastic yarn that is discriminable even from the top of a non-woven fabric without losing the processability and adhesiveness of the paper diaper manufacturing process, and has a fastness that can sufficiently withstand practical use and does not lose its color. . Further, it is possible to produce polyurethane elastic yarns colored in many kinds of colors without polluting the polyurethane elastic yarn manufacturing process and without affecting the physical properties of the polyurethane elastic yarn.

It is explanatory drawing of the process provided with a fiber processing agent, when the undiluted | stock solution discharged from the spinning nozzle falls by the free fall from the inside of the heated spinning tower, and is wound up in the state converged uniformly. It is explanatory drawing of the method of evaluating adhesiveness by notching the polyurethane elastic yarn adhere | attached on the nonwoven fabric, and measuring the distance pulled back.

Claims (8)

  A polyurethane elastic bobbin for paper diapers, wherein the yarn has a color difference ΔE of 20 or more and 80 or less, and is wound in a state of containing or adhering a lipophilic dye.   2. The polyurethane elastic bobbin for paper diapers according to claim 1, wherein the color difference variation in the bobbin is 2 or less.   The polyurethane elastic bobbin for paper diapers according to claim 1 or 2, wherein the fiber treatment agent containing polydimethylsiloxane as a main component is wound in a state of containing or adhering to 0.5 to 10.0 wt%. Yarn body.   The polyurethane elastic bobbin for paper diapers according to any one of claims 1 to 3, wherein the yarn fineness is 155 to 3000 dtex.   The difference in ΔE indicating fastness before and after being immersed in physiological saline at 40 ° C for 24 hours is 1.0 or less, for paper diapers according to any one of claims 1 to 4 Polyurethane elastic bobbin.   The polyurethane elastic bobbin for paper diapers according to any one of claims 1 to 5, wherein the lipophilic dye is at least one of an azo type or an anthraquinone type. The polyurethane elastic yarn wound body for paper diapers according to any one of claims 1 to 6, wherein the polyurethane elastic yarn contains a copolymerized diol unit having at least a unit represented by the following (I).

(Wherein R ₁ is a C ₁ -C ₃ alkyl group, R ₂ is H or a C ₁ -C ₃ alkyl group, m and n are integers of 1 to 3)   A fiber treatment agent containing 10 wt% or more of polydimethylsiloxane and 0.1 to 10 wt% of a lipophilic dye dissolved or dispersed is attached to 2.5 to 5.0 wt% of a polyurethane elastic yarn and wound. The manufacturing method of the polyurethane elastic bobbin for paper diapers in any one of Claims 1-7.

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