JPH06102068B2 - Water absorbent shrinkage material and disposable diaper using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water-absorbing shrink material and a disposable diaper using the water-absorbing shrink material. More specifically, a non-woven fabric that shrinks due to water absorption and a yarn (yarn, twisted yarn, cord, etc.) that shrinks faster and at a higher rate than the non-woven fabric are integrated, and aiding the water-absorbing shrink material The present invention relates to a disposable diaper that is used as a water absorbent body at an edge portion.

<Prior Art> Various types of diapers have been proposed in the past, but the edge of the diaper used has a function of closely contacting the user's thigh to prevent leakage of urine and the like. The following three types of structures are known as specific means for that.

(A) An elastic body (tape-shaped or thread-shaped) such as polyurethane or rubber is used for the edge portion of the diaper and the elasticity is used to bring the edge portion into close contact with the user's thigh.

(B) A thread that shrinks due to water absorption is used for the edge portion of the diaper so that water such as urine excreted by the user is absorbed by the water-absorption shrinkable thread, and the shrinkage generated at that time is used to generate the edge. The part that makes the part adhere to the thigh.

(C) A combination of the method (a) and the method (b).

Among these three methods, the (b) method has the advantages that the product packaging before use is smaller than that of the (a) method, is convenient to carry, and has little stuffiness. It has been transformed into FIG. 3 shows an example of the cross section in the lateral direction. In the figure, 5 is a back sheet made of polyethylene film having a thickness of about 25 μ, 6 is a water absorbing body for absorbing water such as urine, and 7 is a surface. The sheet 8 is a water-absorbing shrinkage thread that shrinks due to water absorption to bring the end edge of the diaper into close contact with the thigh when used, and the portion B is a seal portion for fixing the water-absorbing shrinkage thread at a fixed position of the edge ( Adhere the front and back sheets)
Is. For a diaper using this method (b),
While having the above-mentioned features, when a larger amount of water absorbed by the water-absorbing shrinkable yarn reaches the edge portion, the shrinkage of the water-absorbing shrinkable yarn cannot be done in time and the water leaks from the edge portion. There is. In order to prevent this phenomenon, for example, JP-A-57-
As disclosed in Japanese Patent No. 35002 and Japanese Patent Laid-Open No. 57-56502, water absorbent paper or the like is absorbed before the water absorbed by the water absorbent naturally leaches out to the edge (as early as possible). A method has been adopted in which a part of the water that is positively absorbed by the water absorber is guided to the water-absorbing shrinkable yarn by the auxiliary means, and the shrinkage due to the water-absorbing shrinkable yarn is expressed early (the water-absorbing yarn shown in FIG. 3). Paper does this work). However, even with this method, in an abnormal use condition (for example, when the user lays sideways and urinates, or when severe diarrhea is discharged), the contraction of the water-absorptive contraction thread cannot be completed in time, and the problem of leakage can be solved. It's never done.

Also, when using water absorbent shrinkage yarn for the edge of the diaper, if the water absorbent body and the water absorbent shrinkage yarn are used in superposition, the bulkiness of the water absorbent body itself is high, and the water absorbent body itself does not shrink and the dust end Edge contraction does not occur. Therefore, it has been an essential condition that the water-absorbing shrinkable yarn is used independently of the water-absorbing body and is placed almost independently at the edge of the diaper. (JP-A-57-35
002, JP-A-57-56502). However, the water-absorbing shrinkage thread used for the edge of the diaper after use generally has a diameter of 0.
Since it is a filamentous material of about 5 to 0 mm, it is considered that when used alone, it causes streaks due to depressive blood on the thigh when it adheres to the thigh, and there is no medical adverse effect on the user. However, when the user is an infant, it may cause anxiety to the mother, and this is also a big problem with the method (b).

The method (c) is also a combination of the method (a) and the method (b), and has the same problems as described above.

<Problems to be Solved by the Invention> When the present invention is used as a shrink material for the edge portion of a diaper when it is used, the present invention prevents the diaper from leaking, and causes streaks due to depressive blood on the thigh. Provided is a water-absorbing shrinkage material that does not cause stuffiness in the crotch part, and has the ideal performance that the folded form before use is small (compact), and can be used to make a disposable diaper. The present invention provides a disposable diaper using a material as an auxiliary water absorbent body.

<Means for Solving the Problem> The present invention relates to a water-absorbing shrink material having an elongated shape, characterized by integrating a nonwoven fabric that shrinks due to water absorption and a yarn that shrinks at a higher speed and a higher rate than the nonwoven fabric due to water absorption, and The water-absorbing shrinkage material is used for the longitudinal edge of a diaper to provide a diaper for use that does not have urine or other leakage and has no streaks on the thighs.

Furthermore, the water-absorptive shrink material according to the present invention preferably has the following characteristics.

a) In 20 ° C water, the maximum shrinkage ratio in the length direction is 30% or more, the time to reach 30% shrinkage in the length direction is 20 seconds or less, the shrinkage stress in the original length state is 100 g or more, until the shrinkage stress of 100 g appears. The time is preferably 20 seconds or less. This is because if a water-absorbing shrinkage material having insufficient initial properties relating to water-absorption shrinkage is used for the edge portion of the diaper, leakage may sometimes occur.

b) It is preferable that the shrinkage stress in a water-absorbed state after 30% contraction in the length direction and immersion in 20 ° C. water for 8 hours is 30 g or more and the tensile breaking strength is 1 kg or more. If the sustainability after absorbing these water is insufficient, the diaper using the water-absorbing shrink material may not be able to expand or contract sufficiently in accordance with the movement of the user and the adhesion to the thigh may be insufficient, or the user may move violently. This is because there may be a case of disconnecting when the

c) The non-woven fabric that shrinks when it absorbs 200 g / m ² of water at 20 ° C
Absorbs more than the above, and the shrinkage ratio in the length direction in 20 ° C water is
It is preferably 10% or more and the basis weight is 30 g / m ² or more.
Urine, etc. may leak out from a non-woven fabric with a water absorption capacity of 200 g / m ² or less, and a non-woven fabric with a basis weight of 30 g / m ² or less may cause streaks on the thigh due to water-absorption shrinkage threads. . This is because if a non-woven fabric having a contraction rate in the longitudinal direction of 10% or less is used, the non-woven fabric may have a gusset at the time of contraction of the water-absorbing shrinkage material, which may cause depression in the thigh due to the gusset. Furthermore, the water-absorbing shrinkable yarn used in the water-absorbing shrinkable material is required to give sufficient initial performance to the water-absorbent shrinkable material, considering the economical efficiency,
The maximum shrinkage rate in water at 20 ° C is 30% or more, the time to reach 30% shrinkage is 10 seconds or less, and the shrinkage stress in the original length state is 150 m.
g / d or more, time to develop stress of 150 mg / d is 10 seconds or less, shrinkage stress in a state of shrinking 30% from the original length is 30 mg / d or more,
It is preferable to include high-speed shrinkable fibers having a dissolution loss of 25% or less.

The most important structural feature of the water-absorptive shrinkage material of the present invention is that a nonwoven fabric that shrinks due to water absorption and a yarn that shrinks at a higher speed and a higher rate than the nonwoven fabric due to water absorption are integrated. As the unifying means, a method of sewing a water-absorption shrinkage thread on the nonwoven fabric (using the water-absorption shrinkage thread for the upper thread or the bobbin thread or both), a method of weaving the water-absorption shrinkage thread on the nonwoven fabric, and a water absorption between two nonwoven fabrics A method in which a shrink thread is sandwiched and needle punching is used for integration is used. Among them, the sewing method is the most preferable in terms of workability and cost.

The water-absorptive shrinkage material according to the present invention is used in addition to the member for the diaper edge portion, and has a water-absorption capacity, a water-absorption contraction property, and a surface-shaped (rather than linear) contraction during the water-absorption contraction. It is also very useful as a blood-sucking material, a hemostatic material, a first aid material for fixing an affected area such as a fracture.

The contents of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the water-absorbing shrink material 1 according to the present invention. In this case, the unit for integrating the non-woven fabric and the water-absorption shrinkage yarn is one in which the water-absorption shrinkage yarn is sewn into the non-woven fabric. In FIG. 1, 2 is a water-absorbing shrinkable nonwoven fabric, 3 is a water-absorbing shrinkable yarn, and 4 is a polyester sewing thread. Further, the present invention provides a disposable diaper that uses a water-absorbing shrinkage material as an auxiliary water-absorbing body without contacting the water-absorbing body and using a means for transmitting moisture. Second example of diapers
Shown in the figure. In FIG. 2, 5 is a back sheet made of polyethylene film having a thickness of about 25 μ, 6 is a water absorbing body that absorbs moisture such as urine, 7 is a top sheet, and 1 is a water absorbing shrink material having a function as an auxiliary water absorbing body. . Also, A ₁ and A ₂ parts in the figure are locations where the top sheet and the back sheet are bonded by means such as heat sealing. These A ₁ and A ₂ are for uniformly causing the shrinkage of the water-absorptive shrinkage material at the edge portion, and are not necessarily an essential condition of the present invention. As is clear from FIG. 2, the water-absorbing shrink material 1 is preferably disposed at the edge of the diaper without being in contact with the water-absorbing body 6, and moisture is not provided between the water-absorbing body 6 and the water-absorbing shrink material 1. It is not necessary to use any means for transmitting.

The features of the water-absorbing shrinkable material of the present invention and the diaper for use using the water-absorbing shrinkable material will be described below.

(I) No streak on the thigh due to depression.

As described above, the water-absorptive shrinkage yarn used in the conventional disposable diaper is a filamentous material having a thickness of about 0.5 to 0.7 mm, but the water-absorption shrinkage material of the present invention is a nonwoven fabric and a water-absorption shrinkage yarn integrated with each other. Since the water-absorptive shrinkage material contracts as a flat surface and adheres tightly to the thigh, streaks due to depressive blood are not or hardly attached to the thigh.

(Ii) There is no leakage from the edge.

The water-absorbing shrinkage material of the present invention has a non-woven fabric as a constituent element, and the non-woven fabric has a function as an auxiliary water-absorbing material, and in addition to the fact that the water-absorbing shrinkage material of the present invention requires a very short time to shrink, Even if a larger amount of water is used than the water absorbing body and seeps out to the edge of the diaper, the water does not leak to the outside from the edge.

(Iii) It is difficult to get stuffy.

The disposable diaper according to the above method (a) is in close contact with the thigh from the time of wearing to the time of removal, and stuffiness tends to occur. In addition, the conventional type (b) has a structure in which the water due to the initial urination after wearing is guided to the water-absorbing contraction yarn by an auxiliary means such as water-absorbing paper as soon as possible, and the non-urination before the initial wearing. Sometimes the edge is loose, but after urination, the edge is in close contact with the thigh. On the other hand, the disposable diaper of the present invention uses a non-woven fabric as a water-absorption shrinkage material, preferably a non-woven fabric having a water-absorption capacity of 200 g / m ² or more, and since the non-woven fabric functions as an auxiliary water-absorbing body due to the water-absorption capacity of the non-woven fabric. It is possible to use a structure that causes shrinkage only when the water absorbed by the water absorbent has leached into the water-absorbing shrink material, and therefore, when such a structure is used, the time from wearing to shrinking can be reduced. Can be greatly delayed, stuffiness is very unlikely to occur.

Next, the structure of the water-absorption shrinkage material of the present invention will be described in detail.

(I) Composition of Nonwoven Fabric The nonwoven fabric constituting the water-absorption shrinkage material of the present invention contains 200 g of water at 20 ° C.
It is preferable that it has an ability to absorb water of not less than / m ² and a self-shrinkage ratio of 10% or more in the lengthwise direction when absorbing water in 20 ° C. water. Furthermore, it is appropriate that the shrinkage ratio upon absorption of water in the length direction reaches 30% or more when it is integrated with the absorption shrinkage yarn with the help of external force. Non-woven fabrics with a water absorption capacity of less than 200 g / m ² are slightly lacking in the function of absorbing the water that has leached from the water absorbent body of the diaper to the edges (that is, the function as an auxiliary water absorbent body). Leakage may occur. Non-woven fabrics with a self-shrinkage rate of less than 10% when absorbing water in the length direction are not sufficiently soft when absorbing water, and reduce the shrinkage characteristics (shrinkage rate, shrinkage rate, shrinkage stress, expression rate) of the integrated water-absorbing shrinkable yarn In some cases, the function as a shrink material may be insufficient, and since it is rough and rigid during water absorption shrinkage, wrinkles may occur in the non-woven fabric, which may cause depression and leakage.

Further, the non-woven fabric preferably has a basis weight of 30 g / m ² or more, particularly 40 g / m ^2.
More preferably m ² or more. If the basis weight is less than 30 g / m ^2, the function of receiving the shrinkage generated in the water-absorbing shrinkable yarn on a flat surface and dispersing it in the width direction may be insufficient, and streaks due to depression may occur in the thigh.

A non-woven fabric with a basis weight of less than 30 g / m ² or a water absorption of less than 200 g / m ² is simply folded or stacked to produce a basis weight of 30 g / m ^2.
m ² or more, you can either naturally effectively used those with water absorption 200 g / m ² or more and basis weight 30 g / m ² less than or water absorption 200 g / m
It is also possible to simply fold or stack a non-woven fabric of less than ² with water-absorbing shrink yarn integrated. That is, the non-woven fabric referred to in the present invention also includes a multi-layer non-woven fabric in which the layers are not joined.

A nonwoven fabric which absorbs 200 g / m ² or more of water at 20 ° C. and has a self-shrinkage ratio of 10% or more in the longitudinal direction in 20 ° C. water can be obtained, for example, as follows. Raw cotton used is 10% in water at 20 ℃
It is a fiber made of a hydrophilic polymer having the above shrinkage ratio. A typical example of such a fiber is a polyvinyl alcohol fiber according to the invention of the present inventors (JP-A-60-2709). That is, a polyvinyl alcohol aqueous solution having a degree of polymerization of 1200 to 3000 and a degree of saponification of 98.0 mol% or more is wet-spun, and the resulting Shinoshino contains water and salts in an atmosphere of 130 ° C. or less at 4 ° C.
After stretching more than twice, the maximum shrinkage temperature of the fiber in water is in the range of 65 ° C or higher and 80 ° C or lower, and the maximum shrinkage ratio is 50.
It is obtained by heat-treating under tension so as to be at least%. The shrinkage rate of the fiber thus obtained in water at 20 ° C. is about 35%.

Further in addition thereto, hydrolyzed poly acryloxypropyl nitriloacetate (-COOX nitrile groups, X = Li, K, obtained by introducing Na, the NH _4), carboxymethylated cellulose, fibers consisting of acrylic acid graft products of cellulose Etc. can also be used suitably.

The nonwoven fabric used in the present invention is produced by a dry method mainly using these fibers. When the web taken out from the card or the random web bar contains a normal needle punch system or a system in which a knitted fabric is formed on the surface of the non-woven fabric by the fiber itself (so-called arachne system) and / or a hot melt fiber (binder fiber). Becomes a nonwoven fabric by hot air treatment. It is also possible to manufacture a nonwoven fabric using a resin binder instead of performing needle punching, but in this case, the resin binder adheres to the surface of each single fiber constituting the nonwoven fabric, so the nonwoven fabric's self-shrinkage rate when absorbing water. Therefore, the water absorption capacity is lowered, and thus the needle punch method, the heat fusion method, and the arachne method are more preferable.

The thickness of the non-woven fabric is preferably 0.5 mm to 3 mm. The thickness of the non-woven fabric can be adjusted by the number of needle punches and the calender roll treatment after producing the non-woven fabric, in addition to the basis weight.

The non-woven fabric may contain so-called binder fibers which are heat-meltable as described above. If it contains a heat-meltable binder fiber, it can be used directly as a means to integrate the water-absorbing shrink material into the diaper by directly heat-sealing it to the back sheet and top sheet (sheets shown in FIG. 2 and 5). This is because it is possible to use the method of making it. Further, for a non-woven fabric containing no heat-meltable binder fiber, for example, at the time of sewing with a water-absorption shrinkage yarn, which will be described later, a polyethylene sheet and the non-woven fabric are superposed and sewn, a back sheet,
A method of heat sealing the surface sheet and the polyethylene sheet can also be adopted.

The water absorption of the non-woven fabric can be changed by the unit weight of the non-woven fabric, the tightness, the number of needle punches and the like.

(Ii) Water-absorbing shrinkable yarn As the water-absorbing shrinkable yarn constituting the present invention, the high-speed shrinkable fiber (polyvinyl alcohol fiber) of the invention previously filed by the present inventors as Japanese Patent Application No. 60-246914 is preferably used. it can. The shrinkable fiber is a fiber that reacts extremely sensitively when it comes into contact with water at 20 ° C, and exhibits a large shrinkage behavior with almost no dissolution. Specifically, the maximum shrinkage rate in water at 20 ° C is 30%. Above, 10 times to reach 30% contraction
Seconds or less, shrinkage stress in the original length state is 150 mg / d or more, 150
Dissolution when the time to develop the stress of mg / d is 10 seconds or less, and the shrinkage stress in 20 ° C water is 30 mg / d or more when it is shrunk by 30% from the original length and dispersed in 20 ° C water. It has various properties with a weight loss of 25% or less.

As described in detail in Japanese Patent Application No. 60-246914, such a high-speed shrinkable fiber contains a carboxyl group in an amount of 0.5 mol% to 10 mol%, an average degree of polymerization of 500 to 3000, and a saponification property. Denatured polyvinyl alcohol represented by carboxyl group-modified polyvinyl alcohol with a degree of 77-99.9% 35% -60
Immediately after being ejected from the nozzle, using the 10% aqueous solution as the spinning stock solution.
Cooling zone adjusted to the temperature of 20 ℃ -70 ℃, and 80 ℃
Fibers are formed using a spinning cylinder consisting of a pre-drying zone of ~ 170 ° C, and then dried at a temperature of 110 ° C to 180 ° C to an almost dry state, and the spinning raw yarn thus obtained is 190 ° C.
It is manufactured by a method of performing a stretching heat treatment at a stretching ratio of 4 to 7 times at a temperature of to 230 ° C. Such fast shrink fibers
After being made into a thread having an appropriate thickness, it can be used and can exhibit the initial performance and sustainability required for the water absorbent shrinkage material for the edge portion of the diaper by being integrated with the water absorbent shrinkable nonwoven fabric. .

Furthermore, the highly functional water-absorbing shrinkable yarn, which the present inventors have already filed as Japanese Patent Application No. 60-297942, can be preferably used. The shrinkable yarn is a water-absorbent shrinkable yarn obtained by kneading or twisting a fiber that rapidly shrinks due to water absorption and a fiber that loosens and shrinks due to water absorption, and has an initial shrinkage performance due to water absorption (shrinkage rate during water absorption, shrinkage rate during water absorption, water absorption rate). Shrinkage stress, shrinkage stress development rate at the time of water absorption) is expressed by the fiber that shrinks rapidly due to water absorption,
It is a hybrid yarn in which sustainability after water absorption (shrinkage stress after water absorption, shrinkage stress after water absorption at 35 ° C., strength after water absorption) is shared by fibers that shrink and shrink due to water absorption. The water-absorbing shrink yarn is 20 ° C
The maximum shrinkage rate in water is 30% or more, the time to reach 30% shrinkage is 10 seconds or less, and the shrinkage stress in water at 20 ° C in the original length state is 30 mg / d or more, until the shrinkage stress of 30 mg / d appears. Is 10 seconds or less, and the shrinkage stress is 10 mg / d or more in the water-absorbed state when immersed in water at 20 ° C for 16 hours in a state of shrinking 30% from the original length, and the strength in this state is 300 m.
It is described in Japanese Patent Application No. 60-297942 that the content is g / d or more.

Regarding the method for producing such a water-absorbing shrinkable yarn, Japanese Patent Application No.
-297942, which is described in detail in the patent specification filed above, the production method is described in the above-mentioned Japanese Patent Application No. 60-
High-speed shrinkable fiber obtained by the invention of 246914 and the above-mentioned JP-A-60
It is obtained by mixing or spinning fibers obtained by the method described in JP-A-2709.

However, the water-absorbing shrinkable yarn used in the present invention is not limited to the above. In addition, the thickness of the water-absorption shrinkage yarn is the point of integration with the non-woven fabric and the prevention of streaks due to depression.
200 to 5000 dr is preferable.

(Iii) Method of integrating non-woven fabric and water-absorbing shrinkable yarn The non-woven fabric and water-absorbing shrinkable yarn are integrated by using the water-absorbing shrinkable yarn as both the upper thread and the lower thread, or the upper thread and lower thread, and sewing them together using a sewing machine. To be achieved.

Main stitch is the preferred sewing method, and the pitch of the seam is 1 to 10 mm.
Is preferred. When the water-absorptive shrinkable thread is used as the upper thread or the lower thread, the other thread does not necessarily have to be a thread that contracts when it absorbs water, and if it is a thread having sewability, it is used for ordinary clothing and industrial materials. Sewing threads made of natural fibers, chemical fibers and synthetic fibers, such as cotton threads, polyester threads, vinylon threads, nylon threads, etc., can be used. Although there is no limitation on the thickness of the sewing thread, a thinner thread is preferable in consideration of the condition when using the diaper and economy, and a thread having a sewing thread number of 60 to 100 is preferably used.

The integration of the water-absorbing shrinkable yarn and the water-absorbing shrinkable non-woven fabric can also be achieved by knitting using the water-absorbing shrinkable yarn as the knitting yarn. That is, the water-absorbing shrinkable yarn and the water-absorbing shrinkable nonwoven fabric can be integrated by knitting the water-absorbing shrinkable yarn at the same time as manufacturing the nonwoven fabric or while feeding the previously-prepared nonwoven fabric. At this time, the warp pitch (interval) is preferably 3 to 10 mm, and the number of courses is preferably 3 to 25 / in.

In addition to the above method, the integration of the non-woven fabric and the water-absorbing shrinkable yarn can also be achieved by needle-punching by sandwiching the water-absorbing shrinkable yarn between two water-absorbing shrinkable nonwoven fabrics in a sandwitch shape. Furthermore, an integration method other than these methods may be used.

The integrated product of the water-absorbing shrinkable yarn and the water-absorbing shrinkable non-woven fabric thus obtained is slit into a tape-like material having a width of 5 mm to 4 cm, preferably 1 to 3 cm to be a water absorbent shrinkage material. It is preferable that there are two or more rows of water-absorption shrinkage yarns in the water-absorption shrinkage material. Further, the water-absorptive shrinkable yarn is preferably integrated in the longitudinal direction of the tape-shaped water-absorptive shrinkable material in order to fully exhibit its shrinkability. Of course, this does not mean only the state where the water-absorbing shrinkable yarn is integrated in a straight line in the longitudinal direction, but is integrated so that the shrinkage of the water-absorbing shrinkable yarn contributes to the shrinkage of the water-absorbing shrinkable material in the longitudinal direction. Means all states that

The water-absorbing shrink material having the above-mentioned structure must be used effectively as a water-absorbing shrink material for the edge of the diaper, and has the following performance in consideration of all usage conditions of the diaper. Is preferred.

i) Shrinkage upon absorption of water: Maximum shrinkage in the longitudinal direction in water at 20 ° C (hereinafter referred to as shrinkage upon absorption of water) is 30% or more, and
The time to reach 30% contraction (hereinafter referred to as contraction rate when absorbing water)
It is preferably 20 seconds or less. If the shrinkage rate after water absorption is less than 30%, it may not be possible to make sufficient contact with the user's thigh. The shrinkage rate upon water absorption and the shrinkage rate upon absorption of water greatly depend on that of the water-absorptive shrinkable yarn, but it also depends on the water-absorptive shrinkage of the nonwoven fabric, and a nonwoven fabric with a water-absorption shrinkage ratio of 10% or less is not preferred.

ii) Shrinkage stress upon absorption of water: The shrinkage stress in the original length of water at 20 ° C (hereinafter referred to as contraction stress upon absorption of water) is 100 g or more, and as the time when 100 g of contraction stress upon absorption of water (hereinafter referred to as contraction stress development rate upon absorption of water) Is preferably 20 seconds or less. If the shrinkage stress during absorption of water is low, it may cause leakage even if the force for keeping the diaper end edge in close contact with the thigh after use is insufficient. The shrinkage stress upon absorption of water and the contraction stress development rate upon absorption of water are substantially determined by that of the contraction yarn.

iii) Shrinkage stress after water absorption The water absorption shrinkage material after water absorption shrinkage has rubber-like elasticity, specifically, the shrinkage stress in the water absorption state when immersed in 20 ° C water for 8 hours in a state of being shrunk by 30% from the original length. (Hereinafter referred to as shrinkage stress after water absorption) is preferably 30 g or more. If the contraction stress after absorption of water decreases during use, the edge of the diaper that is already used may lack the ability to expand and contract according to the movement of the user, resulting in poor adhesion to the thigh. Occurs. The shrinkage stress after absorbing water is almost determined by that of the absorbing shrinkage yarn,
Since it is integrated with the non-woven fabric, it shows a higher value than that of the water-absorbing shrinkable yarn itself.

iV) Strength after water absorption shrinkage: Tensile rupture strength (hereinafter referred to as strength after water absorption) in a water absorption state after immersion for 8 hours in water at 20 ° C with 30% shrinkage from the original length means 1k
It is preferably g or more. This is to prevent the absorbent shrinkage material from being cut due to the user's violent movement after the absorbent shrinkage material shrinks by 30% or more and swells with water when the diaper is not worn properly. This is because it is necessary to consider it.

Next, a disposable diaper using such a water-absorbing shrinkage material will be described. As described above, the water-absorbing shrinkage material of the present invention has a water-absorbing ability, and the water content of the urine or the like absorbed in the diaper after being used cannot be completely absorbed by the water-absorbing body until the water-absorbing shrinkage material is absorbed. Since it only has to move, there is no need for a means for guiding water between the absorber and the water-absorbing shrinkage material. Rather, the means has a negative effect, so that the water-absorbing body and the water-absorbing shrinkage material are not in contact with each other. Is preferred. This is because the water-absorbing shrinkage material functions as an auxiliary water-absorbing material, so that it is only necessary to start shrinking when water leaks from the water-absorbing material and reaches the water-absorbing shrinkage material. If the water-absorbing shrink material contracts early, it causes stuffiness. In the disposable diaper using the water-absorptive shrinkable material of the present invention, a conventionally used elastic body such as polyurethane may be used in combination.

The preferred embodiments of the water-absorbing shrink material of the present invention and the diaper for use using the shrink material are as follows, but the present invention is not limited to this embodiment.

Non-woven fabric: A non-woven fabric having a basis weight of 40 to 80 g / m ² and a thickness of 0.5 to 2 mm obtained by needle punching a card web or a random web using a fiber having a shrinkage rate of 20% or more in water at 20 ° C.

Water-absorbing shrinkable yarn: One yarn that rapidly shrinks by absorbing water (for example, fiber 500d / 72f made of polyvinyl alcohol copolymerized with 2 mol% of itaconic acid), and a yarn that shrinks slowly by absorbing water (polyvinyl alcohol is described in the above-mentioned Japanese Laid-Open Patent Publication 60-
An English cotton count 10's / 1 spun yarn obtained by spinning a tow obtained by wet spinning according to the method described in Japanese Patent No. 2709) was combined to produce 3.0t / In (Z) twist.

Water-absorbing shrinkage material: The above-mentioned water-absorbing shrinkage thread is used as the lower thread in the above-mentioned non-woven fabric, and the upper thread is made of the sewing thread number 80 (the cotton thread 80's / 3 polyester sewing thread is used, the stitch pitch is 2 to 5 mm, and the stitch interval is 3 to 5).
Water absorbent shrinkage material sewn in as mm and then cut into a width of 10 to 15 mm. It should be noted that 2 pieces of water-absorbing shrink material should be parallel to the longitudinal direction.
Rows or three rows of seams may be included. The thickness of the water-absorbing shrink material containing the sewing thread is preferably 0.5 to 2 mm.

Disposable diaper: A disposable diaper in which the above-mentioned water-absorbing shrink material is fixed to the edge without contacting the water-absorbing body. No means for guiding water from the water absorber to the water-absorbing shrinkable yarn is used.

As described in detail above, the water-absorptive shrinkage material of the present invention is mainly used for diapers after use, but as described above, it is an emergency material for fixing a blood-sucking material at hemorrhage, a hemostatic material, and an affected area at the time of fracture. It is also used as a treatment material.

The method for measuring the performance of the water-absorbing shrinkable material of the present invention will be described in detail below. All samples to be measured are left in the standard condition (20 ± 2 ℃, relative humidity 65 ± 2%) in advance,
After reaching the water equilibrium, measure under standard conditions.

i) Shrinkage rate of water-absorbing shrinkage material when absorbing water and shrinkage rate when absorbing water so that a load of 1 mg / d in water is applied to the water-absorbing shrinkage material.
The water-absorption shrinkage material is immersed in water of ± 1 ° C., and the immersion time (second) and the shrinkage rate (shrinkage rate with respect to the original length) are measured. And the time (second) to reach the contraction rate of 30% at that time is the contraction rate at the time of water absorption,
The maximum shrinkage ratio within 5 minutes after immersion in water is defined as the shrinkage ratio during water absorption.

ii) Shrinkage stress of water-absorbing shrinkage material and development rate of shrinkage stress of water-absorbing shrinkage material When the initial tension of 5 mg / d is applied to the water-absorption shrinkage material, it is attached to a constant-speed extension type tensile tester with a gripping interval of 10 cm, and then the water-absorption shrinkage material is applied to 20 times. It is immersed in water at ± 1 ° C and the relationship between shrinkage stress and immersion time (seconds) is measured with the grip interval unchanged. Then, the maximum shrinkage stress within 5 minutes of water immersion is defined as the shrinkage stress upon absorption of water (unit: g), and the time required for the shrinkage stress to reach 100 g (seconds) is defined as the rate of contraction stress upon absorption of water.

iii) Shrinkage stress of water-absorbing shrinkage material after absorbing water. The water-absorbing shrinkage material is slackened by 30% with respect to the original length and mounted on a constant-speed extension type tensile tester with a gripping interval of 10 cm, and then the water-absorption shrinkage material is 20 ± 1 ° C. The shrinkage stress after immersion in water for 8 hours with the gripping interval unchanged is the shrinkage stress after water absorption (unit: g).

iv) Strength of water-absorbing shrink material after absorbing water Using the same method as the method of measuring shrinkage stress of water-absorbing shrink material after absorbing water, a sample immersed in water for 8 hours was used with a constant-speed elongation type tensile tester while containing water. Tensile breaking strength is measured. Apply 5 mg / d of initial tension when mounting to the check part.

v) Water absorption capacity of the nonwoven fabric itself Take out a sample of the nonwoven fabric area of 20 to 100 cm ² and determine the area. Then, soak it in water at 20 ° C for 5 minutes, take it out of the water, place it horizontally on the wire mesh and let it stand for 5 minutes to allow excess water to drop, then weigh it and absorb water per 1 m ² area before water immersion. Ask for.

vi) Shrinkage rate of the non-woven fabric itself when it absorbs water A sample strip of about 30 cm in the length direction of the non-woven fabric is sampled, marked exactly at 20 cm, and immersed in water at 20 ° C for dipping time (seconds) and shrinkage rate ( The shrinkage ratio with respect to the original length) is measured, and the maximum shrinkage ratio within 5 minutes of water immersion is defined as the shrinkage ratio during water absorption.

vii) Water absorption shrinkage The measurement is performed in the same manner as the water absorption shrinkage rate and the water absorption shrinkage rate i).

viii) Shrinkage stress of water-absorbing shrinkage yarn and development speed of shrinkage stress of water-absorbing shrinkage are measured in the same manner as ii). However, the rate of contraction stress development during water absorption shall be the time (sec) until the stress development of 150 mg / d.

ix) Shrinkage stress of water-absorbing shrinkage yarn in the state of being shrunk by 30% ii
The measurement is started in the same manner as in i), and the change in shrinkage stress for 5 minutes after immersion in 20 ± 1 ° C. water is measured and the maximum shrinkage stress value within 5 minutes (unit: mg / d) is obtained.

x) Dissolution loss of water-absorbing shrinkable yarn After cutting a sample to a length of approximately 10 mm, 1 to 2 g was sampled and precisely weighed according to JIS L-1013 to obtain the initial amount W ₀
g. Then, the sample precisely weighed in 20 ° C. water having a bath ratio of 200 is dispersed, allowed to stand for 60 minutes, and then filtered using a filter paper of quantitative No. 5A-11 cmφ. When the water droplets that have become unsuitable are dried completely and weighed accurately to obtain Wg, the loss on dissolution is Required by.

xi) The thickness of the non-woven fabric and the water-absorbing shrink material is measured using a dial gauge adjusted so that a load of 10 g / cm ² is applied.

(Note) (i) The load and initial tension applied to the water-absorbing shrink material are calculated by using the total denier of the water-absorbing shrink yarn contained in the water-absorbing shrink material.

(Ii) When the water-absorbing shrinkable yarn is composed of a composite of high-speed shrinkable fiber and other material, only the high-speed shrinkable fiber is taken out and measured.

Hereinafter, the present invention will be described with reference to Examples. Examples 1 to 4 and Comparative Examples 1 to 3 <Production of Water-Absorbable Shrinkable Thread> (1) Production of Yarn that Shrinks Rapidly by Absorption of Water Same as that shown in Japanese Patent Application No. 60-297942. Was prepared as follows. Polyvinyl alcohol modified with 2 mol% itaconic acid (average degree of polymerization: 1800, saponification degree: 97 mol%) was used as a stock solution with a polyvinyl alcohol aqueous solution concentration of 50%, and the spinning raw yarn discharged from the spinneret into the air was subjected to the following conditions: Then, cooling and preliminary drying were performed.

Spindle temperature (cooling zone): 30 ℃ 〃 (pre-drying zone): 110 ℃ Cooling zone length: 0.25m Pre-drying zone: 2.35m Drying temperature: 125 ℃ Atsuta

This spinning raw yarn was drawn 5.5 times through a drawing furnace at 200 ° C.
I got 0d / 72f yarn. This yarn has a shrinkage rate of 62 when it absorbs water.
%, Shrinkage rate at water absorption 4 seconds, shrinkage stress at water absorption 220 mg / d, shrinkage stress at water absorption 4 seconds, shrinkage stress 55 mg / d in a state of being shrunk 30% from the original length, dissolution loss 17%, The function as a high-speed shrinkable fiber was sufficiently satisfied.

(2) Manufacture of soft shrink yarn by absorbing water The following process was carried out using the same method as described in JP-A-60-2709. Average degree of polymerization 1700, saponification degree 99.9 mol%
Wet-spun polyvinyl alcohol aqueous solution in saturated Na ₂ SO ₄ aqueous solution, then stretched 4.5 times in air at 40 ° C and saturated Na ₂ SO ₄ aqueous solution at 90 ° C until it is completely dried in the fixed length condition. Hot air drying at 130 ° C and heat treatment at 170 ° C were performed. Since this fiber is accompanied by remarkable swelling and contraction with water,
Fiber-attached Na under sufficient tension to maintain a constant length
₂ SO ₄ removal water washing 30 ° C. for the purpose of the wet treatment of the oil supply such applied until further to fiber moisture content reaches 40% 80
Dry under tension with hot air at 120 ° C, then 120 ° C. Using the obtained monofilament denier 1.5dr Ito (tow), after cutting with a parlock method, using a ring spinning machine, cotton count 10's / twist number
A spun yarn of 6.8 t / in (Z) was obtained.

(3) Manufacture of water-absorbing shrinkable yarn 500d / 72f yarn (fast-shrinking fiber) which shrinks rapidly due to water absorption shown in Production Example (1), and yarn 10 'which shrinks slowly due to water absorption shown in Production Example (2) s / 1 Each one was combined and twisted into 3t / in (Z).

<Production of Water Absorbing Shrinkable Fiber for Nonwoven Fabric> A crimp was applied to the thread obtained in (2) above to obtain a cut fiber having a fiber length of 51 mm. The shrinkage rate of this fiber in water at 20 ° C. was 35%.

<Non-water-absorptive shrinkable fiber for non-woven fabric> A commercially available vinylon cut fiber (1.5 dr x 51 mm) was used. The shrinkage ratio of this fiber in water at 20 ° C. was 3%.

<Manufacture of water-absorbing shrinkage material> Water-absorbing shrinkage fiber for nonwoven fabric manufactured by the above method 1.5dr × 5
Using 1 mm, a card web was produced by a conventional method. Next, 200p / cm ² × needle punching on both sides is performed and the basis weight is 50g /
A non-woven fabric with m ² and a thickness of 1.2 mm was obtained. 20 ℃ of the obtained non-woven fabric
23% contraction rate in water, water absorption capacity 740g / m ²
It was. This water absorbent shrinkage yarn prepared in (3) was used as a lower thread for this nonwoven fabric, and the polyester sewing thread was 80th count (cotton count 80's /
Using 3) as the upper thread, 3 rows of stitches with stitch pitches of 3 mm were made parallel to the longitudinal direction of the nonwoven fabric at intervals of 5 mm to obtain a water-absorbing shrink material having a width of 2 cm (Example 1). The non-woven fabric used for this purpose and its performance as a water-absorbing shrinkage material are shown in Table 1.

Next, 80% of water-absorption shrinkable fiber for nonwoven fabric made by the above method
And binder fiber NBF (manufactured by Daiwabo Co., Ltd., core: polypropylene, sheath: polyethylene core-sheath fiber, 2dr x 51m
m) 20% was mixed and a nonwoven fabric and a water-absorptive shrink material were produced in the same manner as in Example 1 (Example 2). Table 1 shows the results of performance measurement of the nonwoven fabric itself and the water-absorbing shrinkage material.

In addition, 50% of water-absorption shrinkable fiber for non-woven fabric produced by the above method
And binder fiber NBF 50% were mixed, and a nonwoven fabric and a water-absorption shrinkage material were prepared in the same manner as in Example 1 (Example 3). The results of performance measurement are shown in Table 1.

Further, a non-woven fabric and a water-absorbing shrink material were produced in the same manner as in Example 1 except that the basis weight of the non-woven fabric was 80 g / m ² (Example 4).
The results of performance measurement are shown in Table 1.

On the other hand, a non-woven fabric and a water-absorbing shrink material were produced in the same manner as in Example 1 by using the non-water-absorbing shrinkable fiber for nonwoven fabric (normal vinylon fiber) produced by the above method (Comparative Example 1). The results of performance measurement are shown in Table 1.

Next, a nonwoven fabric and a water-absorbing shrink material were prepared in the same manner as in Example 1 except that the basis weight was set to 20 g / m ² (Comparative Example 2). The results of performance measurement are shown in Table 1.

400p / cm using 80% non-water-absorbing shrinkable fiber for non-woven fabric (normal vinylon fiber) and 20% NBF manufactured by the above method
² x double-sided needle punching to make a non-woven fabric with a basis weight of 30g / m ² and pass through a 140 ° C calender roll 3 times to 0.3mm
A thick non-woven fabric was used as a water-absorption shrinkage material in the same manner as in Example 1 (Comparative Example 3). The results of performance measurement are shown in Table 1.

<Practical test as a disposable diaper> A disposable diaper was prepared using the water-absorptive shrinkable materials shown in Example 1, Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 3 at the edges. Table 2 shows the results of a practical test conducted by wearing it on a 12-month-old infant. The structure of the prepared used diaper is also shown in Table 2.

From the results shown in Table 2, it can be seen that when the amount of water absorption of the non-woven fabric constituting the water-absorbing shrinkage material is small, the function as an auxiliary water-absorbing body is insufficient and leakage of urine occurs. The basis weight of the non-woven fabric is 30 g /
In the case of m ² or less, although the streaks on the thigh due to depressive blood are somewhat reduced as compared with the case where only the water-absorbing shrinkable yarn is used,
No sufficient preventive effect was observed. Further, it can be understood that even if the water absorbent body and the water absorbent shrinkage material are not in contact with each other as a structure of a diaper that is used, a sufficient shrinkage and leakage prevention effect can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view of an example of the water-absorbing shrink material of the present invention, and FIG. 2 is a cross-sectional view of an example of the disposable diaper of the present invention.
FIG. 3 is a sectional view of an example of a conventional disposable diaper.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location D01F 6/14 Z 7199-3B 6/34 Z 7199-3B D04H 1/04 Z 7199-3B 1 / 42 M 7199-3B 1/46 A 7199-3B

Claims (7)

[Claims] 1. A water-absorbing shrink material having an elongated shape, characterized by integrating a nonwoven fabric that shrinks due to water absorption and a yarn that shrinks at a higher speed and a higher rate than the nonwoven fabric due to water absorption. 2. In 20 ° C. water, the maximum shrinkage in the lengthwise direction is 30% or more, the time to reach 30% in the lengthwise direction is 20 seconds or less, and the shrinkage stress in the original length state is 100g or more, 100g shrinkage. The water-absorptive shrinkable material according to claim 1, wherein the time until stress development is 20 seconds or less. 3. A shrinkage stress of 30 g or more and a tensile breaking strength of 1 kg or more in a water absorbing state after being shrunk by 30% in the length direction and immersed in water at 20 ° C. for 8 hours. The water-absorbing shrinkage material described in. 4. A non-woven fabric that shrinks due to water absorption retains water at 20 ° C.
The water absorption according to any one of claims 1 to 3, which absorbs 200 g / m ² or more, and has a shrinkage ratio in the length direction in water at 20 ° C of 10% or more and a basis weight of 30 g / m ² or more. Shrink material. 5. A water-absorbing shrinkable yarn has a maximum shrinkage rate of 30% or more in water at 20 ° C., a time to reach 30% shrinkage of 10 seconds or less, and a shrinkage stress in the original length state of 150 mg / d or more and 150 mg / d. The time until expression is 10 seconds or less, the shrinkage stress in a state of shrinking 30% from the original length is 30 mg / d or more, and the dissolution loss is 25% or less. The water-absorption shrinkage material according to any one of the above. 6. The water-absorbing shrinkable material according to any one of claims 1 to 5, wherein the means for integrating the water-absorbing shrinkable nonwoven fabric and the water-absorbing shrinkable yarn sew the water-absorbing shrinkable yarn into the water-absorbing shrinkable nonwoven fabric. 7. A water-absorbing shrinkage material having an elongated shape in which a nonwoven fabric that shrinks due to water absorption and a yarn that shrinks at a higher speed and a higher rate than the nonwoven fabric due to water absorption are integrated at the longitudinal edge of the diaper to be used. A disposable diaper characterized by being installed as a water absorber.