JP2002004161A - Highly elastic nonwoven fabric and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly elastic nonwoven fabric structure suitable as a base fabric requiring high elastic recovery, such as for a disposable diaper, napkin or a cataplasm. SOLUTION: This composite nonwoven fabric structure is produced by spraying a solution of a thermoplastic elastomer such as the styrene-based one and a polyurethane in a volatile solvent, on a nonwoven fabric web by an airflow to accumulate a sprayed fabric layer, further laminating the nonwoven fabric web on the resultant sprayed fabric layer, and heating and attaching the laminated product by pressure. If necessary, the nonwoven fabric structure is reinforced by interlacing the structure with a water-jet. As a result, the highly elastic elastomer interlaced layer can be inserted without damaging the nonwoven fabric material, and the composite nonwoven fabric structure having >=100% breaking elongation at least at one direction, and >=80% elastic recovery after 100% elongation can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a disposable diaper, a sanitary napkin, a patch material, a protective cover, a supporter, a clothing interlining, and an undergarment material which require a high degree of elongation and elongation recovery. The present invention relates to a highly stretchable nonwoven fabric suitable as a cloth and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, for example, in a disposable diaper, a portion such as a waist or a thigh, which requires elastic contact, is made of a natural rubber or polyurethane-based thread in order to maintain a worn form and to prevent leakage. And tape-like objects have been used. However, these were inevitably localized tensions and were accompanied by discomfort due to the appearance of gathers, and when the diaper was removed, inconveniences such as red tightening marks remained. Attempts have also been made to attach high-elastic nonwoven fabrics to the tightening portions on both sides of the pants-type disposable diaper, but there is still a complaint about lack of tightness. In any case, in recent years, in order to improve the fit to the body, the nonwoven fabric itself has been moving in a direction to have a high degree of elasticity.

The nonwoven fabric itself is still fundamentally unsatisfactory in terms of stretch recovery, and one or more non-elastic nonwoven web layers are provided on the outer surface side of the elastic sheet material to supplement its function. It has been proposed to manufacture a composite nonwoven fabric structure that obtains suitable elasticity, recovery performance, and favorable tactile sensation by laminating them and integrating them by some method. These conventionally attempted methods can be roughly classified into the following three methods.

The first category is a composite structure in which the elastic sheet material is a film of a thermoplastic elastomer, and a nonwoven web is attached to one or both sides of the film. In practice, it has been noted that the film and the nonwoven fabric web are point-adhered and the texture is maintained.
Also, excellent proposals have been made to extend and widen the nonwoven fabric web before and after lamination to control the extensibility and the recoverability, as disclosed in Japanese Patent Publication No. 7-91752, JP-A-5-222601, and JP-A-5-222601. 245961, JP-A-7
No. 252762 implements a systematic composite nonwoven structure of this class. Also, JP-A-7-70
No. 936 proposes an attempt to prevent the thermoplastic elastomer film from becoming uneven by retaining moisture permeability. However, the original purpose is to impart a high degree of elasticity while maintaining sufficient air permeability to the composite nonwoven fabric structure, and lamination with a film as the first classification still suffers from insufficient performance.

[0005] The second category is an elastic nonwoven structure in which the elastic sheet material is formed by melt-blowing or spunbonding a thermoplastic elastomer, and a nonwoven web is laminated on one or both sides of the elastic sheet material. Fusion,
It is a composite nonwoven fabric structure integrated by needle punching, hydroentanglement, or the like. For example, Japanese Patent Publication 7-863,
JP-A-4-28059 and JP-A-7-216707 disclose melt-blown nonwoven fabrics or Japanese Patent Publication No. 3-5515.
2. In a series of inventions such as Japanese Patent Publication No. 3-64157, JP-A-4-11062, JP-A-4-257363, and JP-A-7-70902, a polyurethane spunbonded nonwoven fabric is used as an elastic sheet material.

In a state where a nonwoven elastic web mainly composed of a styrene-based block copolymer and formed by a melt blow method is stretched in advance, nonwoven webs made of an inelastic material are laminated, and further heat-sealed. And a nonwoven fabric structure integrated by a hydroentanglement method have also been proposed, for example, Japanese Patent Publication No. 7-37703 and Japanese Patent Publication No. 7-8123.
0, JP-A-62-33889, JP-A-5-27204
3, JP-A-6-10259 and JP-A-6-184897 are known as a series of trials.

A third category is a method in which a thermoplastic polyurethane is melted by heat, and collected and integrated on a non-elastic nonwoven web in a melt-blown manner.
2 is proposed. As a similar method, JP-B-7-35631 and JP-A-7-197382 can be mentioned as a method of collecting a thermoplastic polymer on a nonwoven web by spraying a hot-melt adhesive, but this is far from the object of the present invention. .

[0008]

In any case, attempts to produce a composite nonwoven fabric structure having elasticity, which has been proposed and used in part, have been carried out in advance by using an elastic nonwoven sheet in a separate step. The basic method is to prepare and laminate an inelastic short fiber web structure by a specific means, or to form and integrate the short fiber web. The elastic nonwoven fabric prepared in another step is in the form of a normal sheet, wound on a roll, and discontinuous.
In addition, since the production process is different from the final production of the composite stretchable nonwoven fabric, it cannot be said that it is necessarily advantageous in terms of cost or productivity. The present invention basically aims at achieving the original purpose in a series of steps for producing a composite nonwoven fabric structure.

Although it is different from the object of the present invention, a method in which a hot-melt adhesive used for laminating a nonwoven fabric structure is deposited on an inelastic nonwoven web by melt spinning like a melt blow method ( For example, Tokiko 6-7030
2, JP-A-2-14057), or a method of spraying the same nonwoven web surface by hot melt spraying (for example, Japanese Patent Publication No. 7-35631, JP-A-7-197382,
There are also JP-A-7-91770), but none of these methods has actively formed an elastic non-woven fabric layer and exerted an elastic function. A structure in which a thermoplastic elastomer having substantially no air permeability is bonded is far from the original object of the present invention.

[0010] Each of the elastic nonwoven fabrics obtained by molding these stretchable thermoplastic elastomers by a so-called melt blow method elutes the elastomer fluidized by hot melting from a die, and puts the long fibers (that is, filaments) while placing them in a hot air flow. Basically, it is deposited in a non-woven form. Therefore, since these filamentous fibers are bonded by thermal means, the hand becomes hard at the bonded portion, and there is a disadvantage for the purpose of providing a moderate elongation recovery property that the fiber is gently and sufficiently expanded. For example,
When applied to the waist around the diaper or the elastically tightened part of the thigh, it can be worn without any resistance depending on its thickness, and it has a strong tightening feeling and has enough recovery to prevent slippage There is a problem with the control of the texture. The same problem remains with the joining method only by thermal means.

[0011] Thus, the present invention has a function of solving the above-mentioned problem and having a function of not being excessively stiff at the time of elongation and rapidly recovering from elongation as expressed by the phrase "fit gently and stretched". Further, it is an object of the present invention to provide a highly stretchable nonwoven fabric structure having essentially air permeability. Furthermore, the present invention is a method for producing a composite high-stretch nonwoven fabric in a substantially continuous production process, taking into consideration that it can also be used for applications originally used at low cost such as disposable diapers. Is provided.

[0012]

According to the present invention, a short-fiber non-woven web of a first layer and a solution of an organic solvent of a thermoplastic elastomer as a second layer are discharged by an air stream, and the solvent is evaporated under the volatilization of the solvent. A composite in which a short fiber nonwoven web spread fabric and / or a short fiber nonwoven web is further laminated as a third layer and integrated by heat and / or high pressure columnar water flow. A composite woven fabric structure is provided, wherein the composite structure has a breaking elongation in at least one direction of at least 100% and at least 10%.
The present invention discloses a highly stretchable nonwoven fabric characterized in that the elongation recovery rate after 0% elongation is 80% or more, and a method for producing the same.

As used herein, the term “highly stretchable”
The elongation at break in at least one direction is 100% or more and 10
It is defined as a material whose elongation recovery rate after 0% elongation is 80% or more. For example, a specimen having a length of 10 cm in one direction can be stretched for 20 cm or more without substantial material destruction, and after elongating to 20 cm, the load is released and the length is reduced to a value shorter than 12 cm. Means to recover.

[0014] The term "short fiber nonwoven web" refers to a carding method, a random webbing method,
It is defined as a material that is spread and accumulated by an air opening method or the like, and is further entangled by means such as a water entanglement method, a heat fusion method, and a needle punching method as necessary.

“Thermoplastic elastomer” in the present invention
Is defined as a polymer material which exhibits elastic behavior like vulcanized rubber at normal temperature, but which can be plastically flowed at high temperature, that is, heated, and which can be molded by various plastic processing machines. Elastic behavior is at least 250%
It is a property that it can be stretched without material destruction over the above, quickly return to the original shape by deloading, and does not leave permanent set of 20% or more. This property is derived from the molecular structure of a polymer component comprising a rubber component (soft block or soft segment) exhibiting elasticity and a resin or a crystal component (hard block or hard segment). That is, a thermoplastic elastomer requires both a soft segment having entropy elasticity and a hard segment as a molecular constraint component for preventing plastic deformation or flow. By acting as such a crosslinking point, elastic behavior is exhibited.

[0016] Furthermore, "spread fabric" means that a solution of a volatile organic solvent of a polymer material having partial crystallinity is sprayed and discharged together with an air stream, and the solvent is volatilized and dried while being scattered in a fibrous form. It is defined as a nonwoven fabric-like material obtained by accumulating thread-like materials. The thickness of the fibrous material is irregular, and its shape and length are not constant but discontinuous, and therefore, it becomes short fibrous. Further, although it changes depending on the degree of drying at the accumulation point, that is, the residual degree of the solvent, the fibrous material partially adheres to form a three-dimensionally entangled structure, and exhibits practically sufficient strength. In addition, the superposition of short fibrous materials or the control of the adhesion point at the entangled portion is easy, so that the texture of the nonwoven structure is extremely soft. In order to scatter the polymer solution in a fibrous form when sprayed, the spinnability of the material becomes a problem, but the thermoplastic elastomer of the present invention has a necessary and sufficient crystalline hard segment. Processing became possible.

[0017] Spread fabric differs from meltblown or spunbonded fibers in spinning method and shape. In the melt blow method or the spun bond method, the molten thermoplastic material is extruded as long fibers or filaments through a die having a large number of thin circular capillaries, and is further finely stretched by a high-speed gas flow or electric means such as static electricity to be assembled. Manufactured by assembling on a surface. Therefore, these fabrics are substantially continuous in the form of long fibers, have a large amount of adhesion at the overlapping portions of the filaments, and have a stiff texture.

The present invention is based on the fact that a spread fabric based on a thermoplastic elastomer is formed as an essential nonwoven fabric layer and in the process of forming a composite nonwoven structure. 1 and 2 show cross-sectional views of a highly elastic nonwoven fabric structure manufactured according to the present invention. In the figures, 1 and 3 are short fiber nonwoven web layers, 2 is a spread fabric layer based on a thermoplastic elastomer, FIG. 1 shows a two-layer structure, and FIG. 2 shows a three-layer (sandwich) structure. . Each layer is partially adhered and integrated by hot pressing to an appropriate temperature (indicated by a in FIGS. 1 and 2, respectively), and further, as illustrated by b, a short fiber nonwoven web Short fibers are entangled in the second layer by the high-pressure columnar water flow from the first or third side to form a structure.

The spread fabric is formed by spraying a solution of an organic solvent of a thermoplastic elastomer by a stream of air and depositing the solvent into a web as substantially dried short fibers while evaporating the solvent. In this method, a relatively low-viscosity high molecular weight polymer solution is extruded into the atmosphere at a relatively low temperature and low pressure as a fine stream at a high speed, and the spinning property of the polymer solution is utilized. A feature is that a bundle of ultrafine short fibers is formed by quickly evaporating and drying the solvent. Therefore, the manufacturing and control apparatus can be greatly simplified, and it is advantageous even in consideration of the processing apparatus for the organic solvent to be used.

The thermoplastic elastomer used in the present invention is a block polymer having a soft segment exhibiting rubber elasticity in a polymer and a hard segment functioning as a crosslinking point of a vulcanized rubber. Particularly preferred materials for the present invention are those having a relatively low boiling point and being soluble in a highly volatile organic solvent, and that the elastomer solution can exhibit sufficient spinnability from the requirements of the construction of the spread fabric. Required. The first group is polystyrene-based block polymers. Here, a polystyrene as a hard segment forms a cross-linking point as a spherical aggregate phase, and is dispersed in a continuous phase of a soft segment. Depending on the selection of the soft segment, block polymers such as styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene / butylene / styrene (SEBS), and styrene / ethylene / propylene / styrene (SEPS) , Or random SBR hydrogenated product (HSBR)
Is a suitable example. Since these elastomers are produced by ionic polymerization or hydrogenation reaction in a hydrocarbon solvent having a relatively low boiling point, it is also a special point that the reaction solvent can be used as it is in the present invention.

A second preferred polymer is a polyurethane-based segmented polymer. Here, a polyol having a molecular weight of 500-5000 and having both terminal hydroxyl groups such as polyalkylene ether, polyester, polyesteramide, and polycarbonate is used as a soft segment component, and a crystalline hard segment is introduced by a reaction between an organic diisocyanate and a chain extender. Obtained by Polyurethane can be widely changed in physical properties by changing the type of the reaction component, the molecular weight of the soft segment component, and the use ratio of each component, and is designed according to the object of the present invention. Also in the case of polyurethane, since it is generally produced by a solution polymerization reaction, the reaction solvent can be used as it is in the present invention.

In addition, although it is difficult to use it alone due to poor spinnability, a polydiolefin-based thermoplastic elastomer such as syndiotactic poly-1,2-butadiene (RB) and trans polyisoprene (TPI)
Since it is relatively inexpensive, it can be used in an appropriate amount mixed with the first and second polymers. Other thermoplastic elastomers, such as polyester-based, polyamide-based, and chlorine-based polymers, are not very suitable for the present invention in terms of the volatility of the solvents that can be used.

In the present invention, the thermoplastic elastomer is used in a solution state. As the organic solvent, a relatively low boiling point, high volatility, low cost, non-toxic one is required,
Preferred examples include n-hexane, cyclohexane,
Examples include hydrocarbon solvents such as toluene and p-xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and ester solvents such as ethyl acetate and n-butyl acetate. Dimethylformamide, which is a good solvent for polyurethane, can also be used as a necessary component. For these, it is effective to use the polymerization solvent itself. Table 1 picks up the properties of the main organic solvents used in the present invention.

[0024]

[Table 1]

In Table 1, the volatilization rate ratio is acetic acid-n-
It is a numerical value with butyl being 100. The volatile and dry state of the solvent while the fine stream of the elastomer solution discharged from the spray nozzle is deposited on the target surface in the form of short fibers as a spread fabric determines the structure and physical properties of the spread fabric. For this reason, the selection of the solvent is important, and it is particularly preferable to mix solvents having different volatilization rates as necessary.

In the present invention, a relatively low-viscosity solution is used to discharge the polymer solution by a spray method. Depending on the spraying mechanism and equipment, the viscosity used is in the range of 1,000 to 100,000 cps (centipoise), preferably 2,000 to 50,000 cps, and the preheating temperature of the solution is relatively low at room temperature to -80 ° C. Because of the temperature, the solids concentration of the polymer is also adjusted to be relatively low. In consideration of maintaining sufficient spinnability, the corresponding polymer solid content concentration is adjusted within the range of 10 to 50%, preferably 15 to 40%. The temperature of the solution guided to the spray discharge may be room temperature, but heating to a temperature up to 80 ° C. is also a very preferable method.

The spray device for a thermoplastic elastomer solution according to the present invention basically includes a fixed-quantity supply unit for feeding a constant amount of the solution to a spray mechanism, a solution discharge port for discharging the solution in a fibrous form, and a high-speed (heating) ) Consists of a discharge section having an air discharge port. The supply device used for the fixed amount supply unit is
Air pressure may be used because the solution viscosity is relatively low,
There is no particular limitation as long as the solution can be fed at a constant and constant pressure, such as a gear pump or a screw pump. Also, in the supply line, the solution temperature is heated to a constant temperature,
It is further desirable to provide a heating device that can be controlled to be constant in a viscosity range of preferably 2.000 to 50,000 cps. The discharge unit is composed of a base in which solution discharge ports and air discharge ports are appropriately arranged, and is designed according to the purpose. Generally, the nozzle orifice diameter of the solution discharge port is
0.1-3.0 mmφ, preferably 0.2-1.5 mm
φ is used. The discharge air is usually adjusted to be higher than the solution temperature. It is controlled constant at a temperature such as room temperature-100 ° C. The air pressure is provided at 0.2-4 atm, preferably 0.4-2 atm. Further, a configuration and an apparatus are practical, in which the entirety of these discharge units can move in a direction perpendicular to the production line in a so-called traverse or circular manner.

The thermoplastic elastomer solution discharged from the spray device is uniformly sprayed on the surface on which the laminate is to be formed, but the elastomer solution discharged from the spray nozzle forms a small stream to rapidly volatilize the solvent. As it gradually becomes a fibrous solid, it reaches the target surface. The distance from the spray outlet to the surface is critical and determines the structure, hand and strength of the resulting spread fabric. The distance varies depending on the composition, concentration, temperature, and discharge rate of the solvent used, and the temperature, air volume, and air velocity of the air flow, but the distance must be sufficiently adjusted in the range of 20 to 1,500 mm. In consideration of the size of the equipment, preferably, it can be 30 to 1,000 mm,
Conversely, the temperature requirements are appropriately designed. When the distance is short, a large amount of solvent remains, and the short fiber-like aggregate has a remarkable adhesion between fibers, and in an extreme case, the aggregate becomes sponge-like. On the other hand, if the distance is too long, the solvent is substantially completely evaporated and dried, and there is no adhesion between the fibers, and the strength of the aggregate becomes extremely small, which is inappropriate. The texture also varies with changes in these conditions. Therefore, control of these processing conditions is the most important issue in forming a structure having no delamination and good strength and texture, that is, a spread fabric.

The basis weight of the spread fabric formed of the thermoplastic elastomer is designed according to the required characteristics of the target composite nonwoven fabric structure. -1
It is sprayed in the range of 00 g / m ² , practically 15-80 g / m ² . Even with the same required characteristics, the weight per unit area is variable depending on the hardness of the elastomer, that is, the magnitude of the modulus. For example, by using a high modulus elastomer, the weight per unit area can be adjusted to be small. Further, since the physical properties vary depending on the degree of adhesion between the fibers of the spread fabric, the basis weight is also adjusted accordingly.

After the spread fabric is formed, it is heated and dried in order to completely remove some residual solvent. The temperature in this case should never be high,
Care should be taken not to cause a substantial change in the structure obtained. The drying temperature is therefore adjusted in the range of 60-150 ° C., and the wind speed and volume of the drying air are carefully controlled.

In the present invention, a composite nonwoven fabric structure illustrated in FIG. 1 or FIG. 2 is manufactured while molding a spread fabric having a thermoplastic elastomer as a base as described above. That is, the structure illustrated in FIG. 1 is manufactured as a two-layer structure by depositing the elastomer as a short fiber spread fabric layer on a short fiber nonwoven web. The structure illustrated in FIG. 2 is manufactured as a three-layer sandwich structure by further laminating a short fiber nonwoven web on the spread fabric layer of the two-layer structure.

The short fiber nonwoven web used for the first layer and the third layer of the present invention is not particularly limited, and conventionally known webs can be appropriately used according to the purpose. The first layer and the third layer may be webs having the same composition and basis weight, or different webs. As the short fiber material, cotton and rayon, as well as polyolefin, polyester, polyamide and polyacrylic fibers, can be used, and they may be used alone or in combination. Among them, it is preferable to use short fibers having a strong crimp since the elasticity of the web itself is improved. A conjugated fiber that develops a helical crimp by further heating gives the web a high elasticity recovery property and greatly improves flexibility and strength, and is particularly preferable. In this case, the heat treatment for the appearance of crimp is preferably performed after forming and entanglement of the web. In selecting the short fiber material, it should not swell or dissolve in the solvent of the thermoplastic elastomer, and the processing temperature (crimping, drying, laminating, heat fusing,
It is necessary to take into account that there is no substantial change with respect to heat setting. Also, for example, it is necessary to set the crimping temperature higher than the processing temperature by at least 20 ° C. or more so as to maintain the performance and dimensional stability of the web. As long as it is used, use of polyolefin or vinyl fibers such as polyethylene, polypropylene, acryl, and polyvinylidene chloride requires careful use.
The cross-sectional shape, denier, and cut length of the short fiber material are appropriately selected within a range suitable for a general nonwoven fabric.
Those having a denier of about 5 and a length of about 25 to 76 mm are used.

The short fiber material is spread and accumulated by means such as carding, random webbing, and air spreading to form a web. The arrangement of the fibers in this case, that is, the orientation, has an important meaning for the effect of the present invention. For example, by arranging and accumulating most of the short fibers in the machine traveling direction by using several card machines or air opening machines, the composite nonwoven fabric structure of the present invention is hardly stretched in the machine direction and is not stretched in the machine direction. It can be designed to exhibit elasticity exclusively in the direction perpendicular to the machine direction. In addition, by appropriately combining carding machines and adjusting the crossing angle of the fleece spun by the card and integrating them as a web, the elongation of the composite structure in the machine (machine direction) weft (lateral direction) and the balance of elasticity can be achieved. Can also be taken. In the latter case, the web itself can be designed to exhibit high elongation and high elongation recoverability by selecting to use a conjugate fiber for heat crimping. In the present invention, in each case, at least the transverse elongation at break is 100% (2 times), preferably 150%.
(2.5 times) or more.

The obtained web is entangled by a high-pressure water entanglement method or a needle punching method to form a nonwoven web having a stable form. The basis weight of the web varies depending on the target product.
g / m ² . When such a disposable diaper is 10-30g / ^{m 2,} when patch material, such as a base fabric is preferably in the range of 15-80g / ^{m 2.} The thickness and apparent specific gravity are also selected according to these purposes.

FIG. 3 is a conceptual diagram showing an example of a line configuration of a typical apparatus for manufacturing the composite nonwoven fabric structure of the present invention by making full use of the above-described components. FIG. 3 shows FIG.
3B schematically illustrates a line configuration for manufacturing a three-layer structure, that is, a sandwich-like structure. 1
Is a short-fiber non-woven web, which is guided from a delivery device capable of controlling tension through a nip roll 2 onto an endless net conveyor 3. The material of the net conveyor is not particularly limited as long as it allows air to freely pass therethrough. However, a net-shaped conveyor made of stainless steel or the like is preferable in consideration of hot air temperature, removability of the nonwoven web, and durability.

The first step is a step of forming a spread fabric layer on the short fiber non-woven web. The solution 4 of the thermoplastic elastomer is supplied to the spray nozzle by the action of a pump or air pressure, and the compressed air Spray 5 on the web. The line of the elastomer and the air flow is adjusted to a required temperature, and is blown out from a nozzle of a base, and is quickly deposited on the web in the form of short fibers while evaporating the solvent. The volatile solvent is exhausted through the suction duct 7. Regarding processing conditions,

-

The setting is made in consideration of the requirements described in the section. Although the spread fabric layer formed in this process is substantially dried, the solvent is completely dried and removed while passing through the drying furnace 8. The exhaust gas from the furnace containing the residual solvent is guided to the catalytic oxidation combustion device 10 through the dust collector 9 together with the exhaust gas from the duct 7, where it is completely burned, made non-polluting, and released into the atmosphere. It is conceivable that the solvent in the exhaust gas can be reused by collecting it.However, in consideration of equipment costs and running costs, for example, the solvent is completely oxidized and burned under a platinum catalyst, and carbon dioxide and steam are removed. It is advantageous to release as In the present invention, the method for treating these solvents is not particularly limited.

The second step is a step of laminating a short fiber nonwoven web layer and a spread fabric layer. In order to form a three-layer structure as shown in FIG. 2, another short fiber non-woven web 11 is sent out while controlling the tension, and the web is spread through a pre-laminator 12.
Place on the fabric layer. Then, it is heated and pressurized by a hot laminator 13 composed of a heated steel roll and a backup roll lined with soft rubber to be combined and integrated. In this step, the purpose is to eliminate the delamination between the layers, in this case,
It is not preferable that the surface of the heating roll is flat and pressed over the entire surface. If excessive pressure is applied to the entire surface, the density of the spread fabric layer is increased and the number of bonding points with the nonwoven web is increased, resulting in a remarkably hard texture and impaired elasticity. Therefore, it is preferable that partial thermocompression bonding, that is, discontinuous bonding, be limited to the extent that substantial delamination can be prevented. In order to satisfy such a condition, it is necessary to employ a thermocompression bonding mechanism in which a dot-shaped uneven pattern is formed on the surface of the heating roll. In the present invention, the pattern is not limited. The conditions for heat sealing and fixing vary depending on the pattern, depth, area, thickness of the structure to be pressed, and the like of the heating embossing roll, but the heating temperature is 10 to 25 ° C. higher than the softening point of the generally used thermoplastic elastomer. The temperature is preferably low, and the pressure of the roll is preferably in the range of 30 to 200 g / cm.

If it is assumed that the intended composite nonwoven fabric exhibits the required function at this stage, after the lamination process, it is taken up by the winding device 15 through the cooling cylinder 14 to be cooled by cold water.

In addition, when it is desired to minimize the heat-sealing fixation from the required functions and required characteristics and to improve the strength and texture by entanglement between the fibers, the action of the high-pressure columnar water flow further reduces the short fiber staples. It is preferable to add an operation of pushing a part into the spread fabric layer from the web side to integrate the part. For this, a method and equipment known as a high-pressure water jet (water jet) confounding method are used. The high pressure columnar water flow is 0.01-0.
Injection pressure 30-150k from injection nozzle of 5mmφ diameter
It is obtained by jetting water at gf / cm ² G. Injection is from the side of the short fiber nonwoven web, with the two-layer structure of FIG. 1 on one side of the web and the three-layer structure of FIG. 2 on both sides. When a water jet stream is sprayed on the web surface, at least a part of the staple fiber group penetrates to the other side through the gap of the spread fabric layer and forms entanglement between the layers, thereby increasing the sense of unity of the composite structure Let it.

As the equipment of the water jet entanglement method, there are, for example, a Mitsubishi rayon method, a Perfo-Jet method, and the like, and FIG. 3 illustrates a production line according to the Honeycomb method. The structure integrated by the hot laminator 13 is guided to the high pressure water entanglement zone in the third step without being wound up through the cooling cylinder 14. High pressure water flow is the first stage nozzle unit group 1
6. Injected from the second stage nozzle unit group 17 toward the surface of the structure, and sucked by the suction drums 18 and 19. The suction drum also serves as a support for the structure,
The surface of the drum has a perforated structure, and the high-pressure water stream effectively penetrates the structure and is sucked into the drum and returned.
The suction is performed by a vacuum pump 21 connected to a water / water separation tank 20, returned to a water storage tank 23 by a drainage pump 22, and subjected to a process such as filtration. The high-pressure water flow is generated by the high-pressure pump 25 via the water supply pump 24 and sent to the nozzle unit group. Thus, while passing through the first and second stage water jet zones, the structure receives a jet of high pressure water from both surfaces to produce effective fiber entanglement. In the case of the two-layer structure shown in FIG. 1, the first-stage processing is omitted, and this is achieved only by the entanglement processing in the second-stage water jet zone. And cylinder dryer 26
, And wound around a winding device 28 via a cooling cylinder 27 to complete a series of continuous manufacturing steps.

[0041]

According to the present invention, the elongation at break in at least one direction is 10
In order to obtain a highly stretchable composite nonwoven structure having an elongation recovery rate of 80% or more after 0% or more and 100% elongation, a thermoplastic elastomer is produced during the process of continuously producing the nonwoven structure. Is formed and integrated. The physical properties of the composite nonwoven fabric structure are determined by (1) the properties of the nonwoven web and (2) the properties of the thermoplastic elastomer, (3) the conditions for forming the spread fabric, and (4) the processing conditions for bonding and integration.

In the present invention, the physical properties of the nonwoven fabric structure are evaluated based on the high elongation property and the repetitive elongation property.
In the measurement, a test piece having a width of 5 cm and a length of 15 cm was used according to an autograph, a chuck interval was 10 cm, and a pulling and returning speed was 20 cm / min. FIG. 4 shows a typical nonwoven web A used in the present invention, a thermoplastic elastomer film B,
FIG. 3 illustrates the high elongation characteristics of a three-layer composite structure C in which a nonwoven web is laminated on both sides of a spread fabric molded from the elastomer. The abscissa plots the elongation when the material is pulled by applying a load, and the ordinate plots the load (tensile stress), and the curve following the progress is shown as an SS curve. Numerical values are compared and evaluated based on tensile stress at 50, 100, 150, and 200% elongation, and strength (tensile strength) or elongation (breaking elongation) at the time of material breakage.
A: 1.5 d (d is a denier unit representing the thickness of a yarn) polyester short fiber is laminated to a basis weight of 30 g / m ^{2 by} a carding method, and 70 kg / cm from a 0.15 mmφ nozzle.
² is a non-woven web obtained by entanglement treatment with a high-pressure columnar water stream, in which the fibers are oriented so that they hardly stretch in the machine traveling direction (MD) but increase in the transverse direction (CD). As the nonwoven web A is stretched, a stress corresponding to the elasticity of the tissue is generated. However, after passing the point A1 (primary yield point), the resistance due to the entanglement of the fibers is applied, and the stress is rapidly increased. At, their confounding begins to break (secondary yield point), and as they are further stretched, the confounding is sequentially damaged and eventually breaks (A3). B is the SS curve of a 60 μm thick styrene-isoprene-styrene (SIS) block polymer film. Also C
Is a three-layer manufactured by spraying a SIS polymer toluene solution (solid content 25%) onto A to form a spread fabric layer, then laminating A and hot laminating at 120 ° C. S- of structure
It is an S curve.

The repetition elongation property is such that the test piece is for example 1
Elongate by 50% and then relax the load at the same rate to obtain a hysteresis curve. The weighted time is indicated as OUT, and the deweighted time is indicated as IN, 50, 100, 15 respectively.
The elongation characteristics of the material are evaluated by the stress value at 0% elongation. In addition, the ratio of the IN / OUT stress at each elongation% is determined to evaluate the elastic recovery of the material. FIG. 5 exemplifies an SS curve of three consecutive repetitive elongations of a three-layer structure having the SIS-spread fabric as an intermediate layer. Permanent strain can also be determined from the elongation at the intersection of the return (IN) curve illustrated in FIG. 5 with the horizontal axis.

[0044]

[Table 2]

Table 2 shows the measured values of the characteristics of the gathers of typical commercially available pants-type disposable diapers. The gathers used for the measurement were prepared by preparing a required number of thread-like elastic bodies in advance and stretching them to a predetermined elongation ratio to obtain two thermal bond nonwoven fabrics (2.2
d This was obtained by laminating a polypropylene fiber between random webbers, sandwiching it between thermal-bonded basis weights of 25 g / m ² ), fixing with a hot melt adhesive, and then relaxing. This achieves tightness on the waist, thighs, and the like. In the present invention, a novel composite nonwoven fabric structure is proposed in order to improve the gather structure, but the actual values of the tightening force are referred to. For example,
Gathers of this kind are attached to both sides of the waist (waist) of the pants-type diaper. The stress at the time of 50% elongation shown in Table 2, especially natural rubber tape is OUT: 172, I
N: Considering that the weight is 145 g, the sheet material of the present invention is applied to both sides around the waist, and a width of about 5
If you put a cm gore (town, okumi), it will be regarded as one eye. That is, in the present invention, for example, as a 50% elongation stress value of a composite nonwoven fabric structure suitable for a disposable diaper, OUT: 150 ± 30 g / 5 cm width, IN / O
The UT ratio is set to be a value as large as possible, preferably 80% or more. Alternatively, considering that the tightening feeling of the elastic material corresponds to the return (IN) stress, a 50% elongation stress IN: 120 ± 30 g / 5c
It is also appropriate to set the width to m.

Regarding the evaluation of elastic recovery, which is the object of the present invention, the hysteresis loss,
Although numerical values such as permanent set and IN / OUT stress ratio are useful, a 3 cm-wide test piece is stretched to, for example, 150% for 30 minutes, then unloaded, relaxed, and allowed to stand for 30 minutes, and measured at that time. The “residual strain” is adopted as a ratio obtained by dividing the elongation. 150% of the test piece with a length of 10 cm between the marked lines
After stretching, i.e. stretching to 25 cm (15 cm extension) and removing the weight, the length of the test piece is 11.8 cm (1.8 cm extension)
If it had recovered by then, the residual strain would be 1.8 ÷ 15 ×
Calculated as 100 = 12%. The elastic recovery is 88%.

With the above evaluation methods and criteria in mind,
In the present invention, the type, composition, structure, and composition of the nonwoven web and the thermoplastic elastomer are selected, and the molding conditions of the spread fabric, the thermocompression bonding, and the conditions of the high-pressure hydroentanglement treatment are adjusted. A highly stretchable nonwoven fabric structure having a high air permeability, a soft texture and an excellent elongation recovery property is manufactured. In particular, the present invention has been completed with an emphasis on softness not available in the melt blow method of hot-melting a thermoplastic elastomer. The melt blow method has been devised in order to produce a nonwoven fabric made of ultrafine fibers. The polymer is melted at a high temperature of 300-350 ° C, and even at a low temperature of 220 ° C or more, and extruded from a nozzle.
It is formed into a thin fibrous form as a web on a support by a high-temperature air flow of about 500C / sec at a high temperature of about 0 ° C. The collected fibers in the semi-molten state are strongly thermocompression bonded to each other by the heat of the air fluid and the wind pressure. Therefore, the entangled points of the obtained nonwoven web are fused and joined to have a high density and a hard texture. It becomes something. On the other hand, in the method for forming a spread fabric of the present invention, the web is formed by spraying at a low temperature and evaporating and drying the solvent in an air stream having a low wind speed. The adhesion between the fibers is adjusted as needed by the degree of drying of the solvent, and the web has a low density and a soft texture. Although the tensile strength is lower than that of the melt blow method, it does not matter in the multilayer structure of the present invention.

Tables 3 and 4 illustrate the molding conditions and physical properties of typical nonwoven webs formed by the meltblowing method and the method of the present invention. Table 3
Is an example of a comparison of both types with a styrenic block polymer. In the table, SEBS is styrene / ethylene / butylene / styrene, SEPS is styrene / ethylene / propylene / styrene, and SIS is styrene / isoprene / styrene / block polymer.
Is a polypropylene used together to prevent sticking.
Melt blown nonwoven fabrics are melted at a temperature near 300 ° C. and blown with hot air at around 300 ° C., so that the strength of the nonwoven fabric is large but the modulus is high and the hand is not good. Further, since the styrene block polymer having an unsaturated bond is melted at a high temperature, thermal discoloration, deterioration, and the like are concerned, and its use is restricted. In the method of the present invention, since a low-viscosity solution dissolved in a solvent such as toluene is sprayed, molding and drying can be performed even at room temperature, discoloration,
There is no worry about deterioration. Generally, the wind speed is as low as about 2 to 10 m / sec, and the degree of drying of the solvent is adjusted depending on the distance to the support, so that the bonding between the fibers of the fabric itself, and hence the modulus, can be sufficiently controlled. Further, the breaking elongation is sufficiently maintained at 200% or more.

[0049]

[Table 3]

[0050]

[Table 4]

Table 4 exemplifies a comparison of both types of nonwoven fabrics using polyurethane elastomers. Here, similarly, in the melt blow method, it is melted at a high temperature of 220 ° C. or more, and the hot air temperature also exceeds 200 ° C.
Polyether-based elastomers have poor thermal stability and large thermal discoloration. Therefore, care must be taken during their use in hot melting. However, in the present invention, there is no problem at all because they are molded at a low temperature. In the table, PTMG-1100 is polytetramethylene glycol (molecular weight 1,100) having hydroxyl groups at both ends, PMPA-1500 is a polyester having a molecular weight of 1,500 from 3-methyl-1,5-pentanediol and adipic acid, PEBA-2500 is a polyester glycol having a molecular weight of 2,500 from 80% ethylene glycol / 20% 1,4-butylene glycol and adipic acid. BHEB is 1,4-bis (β-hydroxyethoxy) benzene, BG is 1,4-
Butylene glycol and MDI are diphenylmethane-
4,4'-diisocyanate. The spread fabric of the present invention has a low strength but a breaking elongation of 200.
%, The modulus can be adjusted sufficiently softly. The fibers are slightly thick and broadly distributed, but have a higher air permeability.

Hereinafter, embodiments of the present invention will be described in detail with reference to examples.

[0053]

EXAMPLES Example 1 Production of Highly Stretchable Composite in the CD Direction Using Styrene Elastomer <Preparation of Short-Fiber Nonwoven Web> 1.5d, Cut Length 4
A parallel card web was prepared from a 5 mm polyester short fiber using a roller card. 25g weight
/ M ² , and the directionality between the machine direction (hereinafter referred to as MD) and the direction perpendicular to the direction (hereinafter referred to as CD) was MD / CD = 7. This web was entangled with a high-pressure columnar water stream to obtain a spunlaced nonwoven fabric. The confounding treatment consists of three water jets: the first stage 0.12 mmφ nozzle, 30 kg / cm ² water pressure, the second stage 0.12 mmφ nozzle, 50 kg / cm ² water pressure, the third stage 0.2 mmφ nozzle, 70 kg / cm ² water pressure. It is implemented by passing through the zone,
The nonwoven web obtained by drying has a basis weight of 27 g /
m ² and thickness 0.22 mm.

This web is used as the first and third layers of a three-layer composite structure as shown in FIG. 2 assuming that the web is for a disposable diaper.
D had physical properties sufficient to elongate. MD CD MD / CD specific tensile strength, kg / 5 cm width 5.7 1.2 4.8 / 1.0 Elongation at break,% 20 235 1.0 / 11.8

<Preparation of Styrene Block Polymer Solution> In order to form a spread fabric layer of a polystyrene elastomer as an intermediate layer of the three-layer composite structure, the polymers shown in Table 5 were selected, and each was uniformly stirred with toluene. Upon dissolution, a spray solution was prepared.

[0056]

[Table 5]

SBS is a styrene-butadiene-styrene block polymer, and SEBS is produced by hydrogenating SBS. For this reason, SBS and SIS have unsaturated bonds, but SEBS is completely saturated and is resistant to thermal stability and thermal discoloration. In general, in the melt blow method, processing is performed at a high temperature, and the polymer having an unsaturated bond is limited. However, in the present invention, since molding is performed at a much lower temperature, low-cost SBS and SIS can be utilized.
In this example, toluene was used as a solvent because commercially available pellets were used, but a polymer polymerization solvent such as n-
Hexane and cyclohexane can be preferably used as they are in the present invention.

<Forming of Spread Fabric> The polymer solution shown in Table 5 was sprayed from a nozzle die arranged at right angles to the traveling direction of the short fiber nonwoven web. The orifice diameter of the nozzle was 0.8 mmφ and the pitch was 2.0 mm. The air flow for spraying was blown out of a slit having a width of 2 mm in parallel with the center line of the orifice array at a distance of 2.5 mm. Blast air pressure is 4 kgf / cm ²
G, the wind pressure at the nozzle outlet is 0.3 kgf / cm ² G,
The wind speed is 12m / sec and the air temperature at the nozzle outlet is about 50
The temperature was adjusted to be ° C. The web, which is the object to be sprayed, was kept almost vertical, and sprayed almost horizontally. The web was backed using a stainless steel mesh of 10 mesh as a support so that the distance from the nozzle could be changed at any time. While heating a 35% solids toluene solution of each polymer to about 50 ° C, the flow rate was 3.
Air was fed and supplied at a rate of 8 g / hole / min. First, a spread fabric was formed on a support without using a short-fiber nonwoven web, and suitable conditions were searched for. The results shown in Table 6 were obtained.

[0059]

[Table 6]

The dry state in Table 6 is “good” when almost all the solvent volatilizes and is fixed in a fibrous form. Conversely, tack refers to a state in which fibrous aebs deposited on a support have sufficient tackiness to adhere to each other.
And The same applies to self-adhesion between fibers. The strength was evaluated as “good” when the deposited web did not elongate and did not break more than 250%, and was ranked according to the degree.

The polymer A had a short fiber length of 3 to 10 mm obtained by spraying, and the spinnability was not so good. In terms of spinnability, polymers C and A are good, and from the viewpoint of drying properties and proper bonding between fibers, spraying at a distance of about 40 cm using SIS or 20-40 cm in SEBS Was the best. Table 3 shows an example of the physical properties of the spread fabric from SIS.

<Preparation of three-layer nonwoven fabric structure>

The polyester spun lace nonwoven fabric (weight per unit area: 27 g / m ² , width: 1.5 m) shown on the both surfaces was used.
A composite structure is prepared with a spread fabric layer from a 35% solution of SIS polymer in toluene. The nonwoven fabric was placed on a 10 mesh stainless steel net conveyor and supplied at a speed of 25 m / min.

The spray nozzles are arranged at right angles to the conveyor. As a polymer discharge port on the nozzle base,
Orifices having a diameter of 0.8 mm were arranged in a line at a pitch of 2.5 mm over a width of 1.5 m, and three or more orifices each having a slit having a width of 2 mm set on each side as air outlets were combined. Therefore, the nozzle plate as a whole has 1,800 holes (1,2).
A nozzle plate having an orifice of (00 holes / m) was kept at a temperature of 50-53 ° C. The distance from the outlet of the nozzle to the conveyor surface was fixed to be 40 cm. Dehumidified air heated to 50 ° C. is supplied with a pressure of 4 kgf
Although the air was blown at a flow rate of 15 Nm ³ / min / cm ² G / cm ² G, the wind speed at the nozzle outlet was measured to be about 10-12 m / sec. A suction / exhaust duct is provided in the direction of air flow, just behind the net conveyor, to exhaust air containing volatile solvents by 25 Nm.
It is equipped to draw at ³ / min. As a result, the air stream blown out from the nozzle plate is fiberized under the volatilization of the solvent while carrying the polymer solution stream linearly,
The air is exhausted from the duct through the nonwoven fabric and the conveyor net. The polymer is deposited as short fibers on the nonwoven fabric.

While continuously supplying the nonwoven fabric on the net conveyor, the SIS polymer (Nippon Synthetic Rubber: JSR-S
A 35% toluene solution of IS-5505) is sprayed and discharged. The solution is heated to 50 ° C. in advance in a pressure tank, adjusted to a flow rate of 7 kg / min while pressurizing with nitrogen gas, and supplied to the nozzle. 50 ° C of the solution
Was 1,780 cps. The solution deposited continuously on the nonwoven fabric with rapid volatilization. The deposited splayed fabric layer was entangled with the fibrous polymer, and also had good self-adhesion to the bonding points and the nonwoven polyester fibers. Next, the same polyester spunlace nonwoven fabric is continuously supplied onto the spread fabric layer by a pre-laminator while continuously supplied. Laminator is 1.5kgf / c
a steel roll having an m ² G steam heating mechanism, and a backup roll lined with soft rubber,
After laminating the second non-woven fabric, clearance 0.3m
and lamination at a pressure of 3 kgf / cm ² G. In this state, since a small amount of solvent still remains, it is completely dried by passing through a hot air dryer at 85 ° C. for about 30 seconds, cooled, and wound up. At this point, the thickness of the three-layer structure is 0.69.
-0.74Mm, no substantial shrinkage in the width direction, basis weight was 110-116g / ^{m 2.}

<Preparation of Composite Structure by Hot Pressing> The resulting three-layered structure has a weak adhesion between the fabric layers and the non-woven fabric, and is slightly easily peeled off. did. The hot press used an embossing method. The embossing roll was provided with a diagonal lath pattern, and was pressed against a backup roll lined with soft rubber to form a point bond, so that elongation and texture were not impaired. The lath is 4.5 × 3.0 mm,
The one having a depth of 0.4 mm was used. For the embossing roll, the roll surface temperature is adjusted to 145 ° C. by a heating medium heating method, the clearance is 0.2 mm, and the pressure is 4 kgf / cm.
² G, running speed 25 m / min. The thickness of the obtained structure is 0.63-0.66 mm, and the basis weight is 108-1.
It was 10 g / m ² . The peel strength between the respective layers was accompanied by material destruction, and all showed a value of 200 g / cm width or more.

<Physical Properties of Composite Structure> Table 7 shows the high elongation characteristics and the repetitive elongation characteristics of the composite nonwoven fabric structure using the obtained SIS elastomer and a spread fabric as an intermediate layer. Here, a comparison is made with a three-layer nonwoven fabric structure (denoted as a commercial product) collected from a commercially available pants-type baby paper diaper. About 25 g of commercial products
/ M ² polyester spunlace on both sides, about 6
It is a stretchable material that has been analyzed as having an intermediate layer of 0 g / m ² SEPS film. FIG. 6 also shows a comparison of the first loop in repeated extension of these structures in the CD direction.

[0067]

[Table 7]

In the comparison of these physical properties, particularly the elastic recovery properties, Table 7 and FIG. 6 show that the material of this example is superior to the commercial product. Further, in order to analyze this relationship, comparing the IN / OUT ratio in repetitive elongation, that is, how much (%) of the energy required for pulling the material returns effectively can be a great indication. Further, by observing the ratio between the first and second tensile stresses, it is possible to estimate the decay of the elastic modulus caused by repeated stretching. Comparing these elastic behaviors with the values in Table 7, it is known that the material of this example is significantly superior to the commercially available product. Example 1 IN / OUT ratio (%) in the first loop of commercially available material 50% elongation 93 100% elongation 26 12 Second / first time stress ratio (%) 50% elongation 44 25 100% elongation 59 47 150% elongation 80 74

Example 2 Production of Highly Stretchable Composite in the CD Direction Using Urethane Elastomer <Preparation of Short-Fiber Nonwoven Web> In the same manner as in Example 1, for the purpose of a three-layer composite structure, polyurethane was used for the intermediate layer. Manufactures materials for disposable diapers with an elastomeric spread fabric. On both surfaces, the same spun lace nonwoven fabric as in Example 1 having a basis weight of 1.5 g polyester fiber of 27 g / m ² and a thickness of 0.22 mm was used.

<Preparation of Polyurethane Elastomer Solution> A polyurethane elastomer solution was prepared by solution polymerization using polyester glycol as a starting material.
As the polyester glycol, a polyol having a molecular weight of 2,500 at both ends hydroxyl obtained by polycondensation of a mixed glycol of 80 mol% of ethylene glycol and 20 mol% of 1,4-butylene glycol and adipic acid was used. 1 mol of this polyol, 2.5 mol of 1,4-butylene glycol and diphenylmethane-4,4 '
-A substantially linear polyester urethane solution was obtained by a solution polymerization method using 3.4 mol of diisocyanate as a starting material. To further facilitate spraying, the solid content was adjusted to a final concentration of 15%, and the viscosity was 760.
Although a solution of cps (30 ° C.) was obtained, the final solvent composition was 15/25 by weight ratio of DMF / toluene / MEK.
/ 60. The film properties of this polyurethane elastomer are 100% modulus 14 kgf / cm
² , tensile strength 190 kgf / cm ² , elongation at break 750%
Met.

<Molding of Three-Layer Structure Using Spread Fabric as Intermediate Layer> The molding of a polyurethane spread fabric was attempted using a handy type coating spray gun. The spray gun is Kitashinsei Seisakusho Model RS-506. The nozzle orifice diameter is 1.
2mmφ, 4kg / cm ² G from flat blown air cap
The solution was spun into a thread by blowing out compressed air. 15% polyurethane solution at room temperature (26-28)
° C), and the supply amount of the solution at this time was 6.7 g /
(A solid content PU of 1.0 g / min).
The solvent of the solution volatilizes well even at room temperature, at least 60
At a distance of more than cm, a good fibrous bundle was obtained.

A polyester spunlace having a basis weight of 27 g / m ² was fixed to a 10-mesh wire net, leaned almost vertically on a spray booth, and moved by a spray gun in a direction perpendicular to the object to be sprayed, that is, horizontally to make it even. Sprayed as follows. The fibrous elastomer was deposited on the spunlace in a spider web and formed a splayed fabric layer, so it was sprayed patiently until the required basis weight was reached. The adhesion between the elastomer and the spunlace was sufficient and the spray layer did not peel off. The distance between the object to be sprayed and the spray gun and the basis weight of the spray layer were changed to prepare two-layer structures, and the same polyester spunlace was superposed on the spray side surfaces to form three layers. Since a slight amount of the solvent was considered to remain, it was dried for 10 minutes using a hot air dryer at 100 ° C.

Next, it was partially adhered and reinforced by hot pressing. The hot press used the same embossing conditions as in Example 1, except that the roll surface temperature was changed to 160 ° C.

[0074]

[Table 8]

<Physical Properties of Composite Structure> Table 8 shows the strong elongation characteristics and the repetitive elongation characteristics of the composite nonwoven fabric structure using a polyurethane spread fabric as an intermediate layer. These results show that the closer the distance between the surface of the spunlace and the mouthpiece of the spray gun is 80 cm, the greater the strength and the quicker the elastic recovery.

FIGS. 7 and 8 show graphs comparing the first loop of repeated elongation of the composite structure obtained in Table 8. In particular, the behavior of the structure of the polyurethane spread fabric intermediate layer having a basis weight of 60 g / m ² obtained by spraying at a close distance of 80 cm shown in FIG. It turns out that they are very similar. It is also very similar in the OUT curve compared to the composite structure with the SIS splayed fabric interlayer shown in FIG. 5, but the position of the IN loop is relatively high and the elastic recovery is higher. It is shown that it is prompt. In this regard, polyurethane is considered to be more preferable than styrene.

Example 3 Production of Polyurethane Spread Fabric Intermediate Layer Composite Structure <Preparation of Short Fiber Nonwoven Web> Polyurethane spread fabric was inserted into the intermediate layer, and polyester spunlace was arranged on both sides. An example of a process for producing a nonwoven fabric having high elasticity in the CD direction for the purpose of a three-layer composite structure will be described. As the polyester spunlace, a material having a basis weight of 27 g / m ² and a thickness of 0.22 mm obtained by using the same 1.5 d polyester short fiber as in Example 1 was selected.
The physical properties of this non-woven fabric

The results were equivalent to those shown in FIG. Width 1.5
m spunlace was previously wound up on a paper tube having an inner diameter of 7.5 mm.

<Preparation of Polyurethane Elastomer Solution> A polyester urethane elastomer equivalent to that in Example 2 was selected. Polyester polyol, 1,4-
Butylene glycol, diphenylmethane-4,4'-
A linear polyurethane elastomer solution was prepared from the diisocyanate by a solution polymerization method. The final solvent composition was DMF / toluene / MEK at a weight ratio of 60 /
It was adjusted to have a mixed composition of 10/30, a solid content of 30%, and a viscosity at room temperature of 120,000 cps. The solution was adjusted to 60 ± 2 ° C. and fed to a spray mechanism, at which time the viscosity was 22,000 cps.

<Preparation of Spray Nozzle> The production line employed in this embodiment has substantially the configuration shown in FIG. As a nozzle head for spraying the elastomer solution, Dyntech Co., Ltd.
Afiber nozzle head was used. The nozzle head was connected at right angles to the traveling direction by connecting four sets of units having a width of 381 mm. The head is provided with nozzle holes having a diameter of 0.5 mm on a straight line at a pitch of 2.54 mm, and thus has about 600 holes over a total width of 1.5 m. The nozzle head was connected so that the solution was fed by a gear pump (75 cc / rpm, 10-90 rpm) for each set. The pipeline was also kept at 60 ° C. Hot air outlets for spraying are provided on both sides of the nozzle hole array, and hot air of 80 ° C. is applied at 0.4 kgf /
It was adjusted so as to blow out with a small pressure of cm ² G. As a result, the solvent of the elastomer solution is quickly volatilized, and at the same time, the fine stream discharged from the nozzle slightly fluctuates, resulting in the formation of a fibrous entanglement. In this embodiment, the distance from the outlet of the nozzle to the conveyor surface is 50.
cm.

<Manufacture of Three-Layer Nonwoven Fabric Structure> An embodiment of this embodiment will be described with reference to FIG. The polyester spunlace, which is the first layer of the composite structure, is hung on a delivery device 1, and is fed onto a net conveyor 3 via a nip roll 2. The speed is adjusted so as to be 30 m / min.

The polyurethane elastomer solution is stored in the tank 4, adjusted to 60 ° C., and fed to the nozzle head 6 by a gear pump. The rotation speed of the gear pump was set to 60 rpm, and the supply amount of the solution was set to 4.5 k.
g / min. As a result, the polyurethane elastomer is formed as a spread fabric having a basis weight after drying of 30 g / m ² .
The feed pipeline is also kept at 60 ° C.

On the other hand, the air for spraying is heated to 80 ° C., and the pressure is adjusted so as to be 0.4 kgf / cm ² G. Thus, the heating air is blown out from the slit of the nozzle head in a countercurrent direction to the fine stream of the elastomer solution, and is vaporized from the solvent in the solution, and is guided from the combustion furnace to the atmosphere through the net conveyor.
The nozzle head is also kept at 60 ° C. in advance. Opening the valve of the polyurethane elastomer solution will substantially initiate spraying.

After completion of the above preparation, spraying is continuously started on the nonwoven fabric on the conveyor, and a small amount of the remaining solvent is guided to the drying furnace 8 to be further dried. This makes the first
A two-layer structure of a two-layer nonwoven fabric and a second-layer spread fabric is obtained.

Next, the polyester spunlace to be the third layer is hung on the delivery device 11 and the nip roll 12
And continuously laminated on the two-layer structure. Further, in order to fix the adhesion, the adhesive is guided to the hot laminator 13 and pressed to form a three-layer structure. The temperature of the heating roll of the hot laminator was set to 135 ° C. in advance. The structure is guided and cooled by a cooling cylinder 14, where a part thereof is taken up by a winding device 15. Separately, the three-layer structure is guided to the next water jet entanglement device, and further processing is added to improve the entanglement between the three layers.

The water jet device is arranged so that a high pressure water stream can be jetted from both sides of the structure in two stages, drums 18 and 19. A nozzle unit is provided on each of the nozzles, and a water jet stream having a water pressure of 50 kgf / cm ² G is jetted from the nozzle of 0.12 mmφ almost perpendicularly to the structure to form a sufficient entanglement. Further, it is dried and cooled by being guided to a cylinder dryer 26 and a cooling cylinder 27, and finally wound up by a winding device 28.

<Physical Properties of Composite Structure> Table 9 shows the high elongation characteristics and the repeated elongation characteristics of the obtained three-layer composite structure. A shows the case where the water jet entanglement process was not performed after the formation of the three-layer structure, and B shows the case where the water jet entanglement process was further performed. From the repetitive elongation characteristics of these structures, it is recognized that all of the structures had a soft texture as compared with A in Example 2.

[0087]

[Table 9]

<Comparison of Elongation Recovery Ratio of Composite Nonwoven Fabric Structure>
The elastic recovery rates of the three-layer nonwoven fabric structures obtained in Examples 1, 2, and 3 were measured. The test is

According to the method specified in the above, a method of elongating a specimen 10 cm in length between the marked lines to 100% for 30 minutes, removing the weight, relaxing, and allowing the specimen to stand for 30 minutes was adopted. It was measured. As summarized in Table 10, all of the composite structures obtained in this example had an elastic recovery rate superior to those of commercially available materials.

[0089]

[Table 10]

[0090]

As described in detail above, according to the present invention, in a series of steps for producing a composite nonwoven fabric structure, a spray fabric layer is inserted by a method of spraying a thermoplastic elastomer solution and evaporating a solvent. The present invention provides a method for imparting high elasticity with an elongation recovery rate of 80% or more after 100% elongation. It has been shown that the method of the present invention can be carried out under extremely low temperature and low pressure as compared with known methods, in order to form fibrous entanglement in a solution state.
As a result, a wide range of fiber materials can be used, and high-speed processing can be performed online. In addition, in the method of the present invention, since the thermoplastic elastomer is formed into a solution and sprayed, an elastomer having a low softening point unlike a known hot melt material and a compounding thereof are not essential, so that it can be used in a state of high performance and high elasticity. Is also a big feature.

Each of the composite nonwoven fabric structures obtained in the present invention shows a large elongation recovery rate. Depending on the selection of the fiber material, the thermoplastic elastomer, the basis weight, and the processing conditions,
It can be seen that a wide range of characteristics can be changed. It was also shown that all of the composite structures obtained in the present invention had characteristics compatible with the intended disposable diaper, napkin, patch material and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a two-layer composite nonwoven fabric structure of the present invention.
In the figure, 1 is a short fiber nonwoven web layer, 2 is a spread fabric layer based on a thermoplastic elastomer, <a> is a structure in which layers 1 and 2 are thermally bonded, and <b> is The schematic diagram of the structure in which each layer was entangled by the high-pressure water flow.

FIG. 2 is a cross-sectional view of a three-layer composite nonwoven fabric structure of the present invention.
In the figures, 1 and 3 are short fiber nonwoven web layers, 2 is a spread fabric layer based on a thermoplastic elastomer, <a> is a structure in which each layer is thermally bonded, and <b> is a structure in which each layer is thermally bonded. The schematic diagram of the structure entangled by the high-pressure water flow.

FIG. 3 is a schematic view showing an example of a line configuration of a typical apparatus for producing a three-layer composite nonwoven fabric structure of the present invention. The names of each device in the figure are shown below. 1: Short fiber non-woven web feeder 2: Nip roll 3: Endless net conveyor 4: Storage / supply tank for thermoplastic elastomer solution 5: Heated pressurized air 6: Nozzle head 7: Suction for volatile solvent Duct 8: Drying furnace 9: Dust collector 10: Oxidation combustion device 11: Short fiber non-woven web delivery device 12: Prelaminator 13: Hot laminator 14: Cooling cylinder 15: Winding device for composite nonwoven fabric structure 16: First stage high pressure Water flow nozzle unit 17: Second stage high pressure water flow nozzle unit 18: First stage suction drum 19: Second stage suction drum 20: Steam / water separation tank 21: Vacuum pump 22: Drain pump 23: Water storage tank 24: Water supply pump 25: High pressure water pump 26: Cylinder dryer 27: Cooling Grayed Cylinder 28: winder as composite nonwoven structure

FIG. 4 is a stress-elongation curve diagram when elongation is applied to a sheet material. A is the polyester used in the examples of the present invention.
Spunlaced nonwoven fabric (basis weight 30 g / m ² ), B is a thermoplastic elastomer (SIS) film (thickness 60
μ), C is a three-layer composite nonwoven fabric structure obtained according to the present invention (Example 1; a structure using a spread fabric formed by SIS as an intermediate layer, a basis weight of 110 g /
m ² ).

FIG. 5 is a three-time repeated stress-elongation curve diagram of the three-layer composite nonwoven fabric structure obtained in Example 1 of the present invention.

FIG. 6 is a graph showing a repeated stress of the three-layer composite nonwoven fabric obtained in Example 1 of the present invention and a commercially available material.
FIG.

FIG. 7 is a repetitive stress-elongation curve diagram of a three-layer composite nonwoven fabric obtained according to Example 2 of the present invention. Comparison of structures in which the polyurethane elastomer solution was inserted as a spread fabric with a basis weight of 85 g / m ² under varying distances from the nozzle to the first layer nonwoven web.

FIG. 8 is a cyclic stress-elongation curve diagram of a three-layer composite nonwoven fabric obtained according to Example 2 of the present invention. Comparison of structures where the polyurethane elastomer solution was inserted as a spread fabric with a basis weight of 60 g / m ² under varying distances from the nozzle to the first layer nonwoven web.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // A61F 13/00 355 A61F 13/00 355F F-term (reference) 3B154 AA07 AA09 AB22 BA31 BA32 BA48 BB02 BB12 BB35 BB62 BE04 BF18 DA30 4C098 AA02 AA09 BC02 CC10 CE05 CE06 DD10 4L047 AA21 AB02 BA04 BA08 BC03 CA02 CC02 CC04 CC05

Claims (4)

[Claims] 1. A short fiber non-woven web of a first layer and a short fiber entangled web of a short fiber thermoplastic elastomer of a second layer,
Alternatively, a short fiber nonwoven web is laminated as the third layer, and the elongation at break in at least one direction is 100% or more, and the elongation recovery rate after 100% elongation integrated by heat and / or high-pressure columnar water flow. Is 80% or more. 2. The woven web of the second layer is a spread fabric in which a solution of an organic solvent of a thermoplastic elastomer is sprayed and discharged by an air stream and accumulated and entangled in a short fiber form under the volatilization of the solvent. The highly elastic nonwoven fabric according to claim 1, characterized in that: 3. An organic solvent solution of a thermoplastic elastomer is spray-sprayed onto a short fiber nonwoven web by an air stream to deposit the elastomer in the form of short fibers while substantially completely removing the solvent. A method for producing a highly stretchable nonwoven fabric, which is followed by fusion by heating and / or entanglement by a high-pressure columnar water flow. 4. A method of spraying a solution of an organic solvent of a thermoplastic elastomer onto a short fiber nonwoven web by an air stream to deposit the elastomer in the form of short fibers while substantially completely removing the solvent. A method for producing a highly elastic nonwoven fabric, further comprising laminating a short fiber web thereon, followed by fusion by heating and / or entanglement by a high-pressure columnar water flow.