JP2010005918A - Moisture-permeable stretchable sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moisture-permeable stretchable sheet having a sufficient moisture-permeability and an excellent stretchability. <P>SOLUTION: A number of elastic filaments 13 arranged in a way that they are not crossed with each other, stretchable in one direction and in a substantially unstretched state are bonded throughout their entire length between a first stretchable non-elastic moisture-permeable sheet 11 and a stretchable sheet 12. Alternatively, a moisture-permeable elastic film 13A is bonded in a substantially unstretched state and throughout its entire length between a first stretchable non-elastic moisture-permeable sheet 11 and a stretchable sheet 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a stretchable sheet having moisture permeability.

  In absorbent articles such as disposable diapers and sanitary napkins, it is non-permeable as a back sheet for the purpose of preventing the occurrence of discomfort and rash due to stuffiness occurring during wearing, and A moisture permeable sheet is used. As such a sheet, a sheet obtained by kneading a filler not compatible with the resin into a synthetic resin and uniaxially or biaxially stretching a sheet melt-formed into a film is generally used. . However, the above-mentioned sheet is generally not stretchable or, if present, is insufficient.

  Therefore, the present applicant has previously proposed several non-permeable moisture-permeable sheets having stretchability (see Patent Documents 1 and 2). However, these moisture permeable sheets have the disadvantage that it is not easy to make the moisture permeability sufficiently high or it is difficult to prevent the occurrence of blocking. Thus, the conventional non-water-permeable moisture-permeable stretch sheet still has room for improvement.

Japanese Patent Laid-Open No. 7-24005 JP-A-8-300531

  Accordingly, an object of the present invention is to provide a moisture-permeable stretchable sheet that can eliminate the drawbacks of the above-described conventional techniques.

  According to the present invention, a first non-stretchable transparent fiber is formed in which a plurality of elastic filaments or elastic strips arranged so as to extend in one direction without crossing each other can extend over their entire length in a substantially non-stretched state. A moisture-permeable stretch sheet joined between a wet film and a stretchable non-stretch sheet is provided.

  In the present invention, the moisture-permeable elastic film is substantially non-stretched between the first non-stretchable moisture-permeable film that can be stretched over the entire length and the stretchable non-stretchable sheet. A moisture-permeable stretch sheet that is joined is provided.

  The moisture-permeable stretch sheet of the present invention has sufficiently high moisture permeability and further has good stretchability. Moreover, the moisture-permeable elastic sheet of the present invention does not cause problems such as blocking.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The partially broken perspective view of 1st Embodiment of the moisture-permeable stretch sheet of this invention is shown by FIG. The stretchable sheet 10 of the present embodiment includes a total of two sheets, a first non-stretchable moisture permeable film (hereinafter referred to as the first sheet 11) and a stretchable non-stretchable sheet (hereinafter referred to as the second sheet 12). It is comprised from the sheet | seat and many elastic filaments 13 clamped between both sheets. Each elastic filament 13 is joined to the first and second sheets 11 and 12. In the present invention, elasticity refers to the original length when the force is released from a state where it can be stretched and stretched 100% of the original length (which is 200% of the original length). The property of returning to a length of 125% or less.

  Each of the sheets 11 and 12 can be extended. However, each of the sheets 11 and 12 is non-stretchable. Each of the sheets 11 and 12 can be extended in the same direction as the direction in which the elastic filament 13 extends. For example, when the sheet is made of a non-woven fabric, the stretchable fibers are (i) when the constituent fibers of the non-woven fabric are stretched, and (b) even if the constituent fibers themselves are not stretched, the fibers that are bonded at the intersection. When the three-dimensional structure formed by multiple fibers is structurally changed due to the separation of fibers, the constituent fibers are torn, the slack of the fibers is stretched, and the whole nonwoven fabric is stretched Including. In the case where the sheet is made of a moisture permeable film, the term “extendable” includes the case where the molecular chain of the constituent resin (such as PE or PP) extends or shifts. In the case where the moisture permeable film contains a substance that is not compatible with the resin constituting the moisture permeable film, it includes a case where peeling occurs at the interface between the resin and the substance that is not compatible and the entire sheet is stretched. Further, in the present invention, non-stretchability means “when the force is released from a state where it can be stretched and stretched 100% of the original length (which is 200% of the original length). In other words, it does not have the property of returning to a length of 125% or less of the original length.

  Each of the sheets 11 and 12 may be already stretchable in the state of the original fabric before being joined to the elastic filament 13. Alternatively, it is not stretchable in the state of the original fabric before being joined to the elastic filament 13, but is processed so as to be stretchable after being joined to the elastic filament 13, and becomes stretchable. Also good. Specific methods for making each of the sheets 11 and 12 stretchable include heat treatment, inter-roll stretching, bite-and-gear stretching by teeth, gears, and tensile stretching by a tenter. In view of a suitable manufacturing method of the moisture-permeable stretchable sheet 10 described later, each sheet 11, 12 has a good transportability when the elastic filament 13 is fused to each sheet 11, 12. 12 is preferably not stretchable in its original state. Further, generally speaking, each of the sheets 11 and 12 does not have stretchability in both the original fabric state and the state after being joined to the elastic filament 13.

  Each elastic filament 13 is substantially continuous over the entire length of the moisture-permeable stretchable sheet 10. The elastic filament 13 contains an elastic resin. The elastic filaments 13 are arranged so as to extend in one direction without crossing each other. However, the elastic filaments 13 are allowed to cross unintentionally due to inevitable fluctuations in the manufacturing conditions of the moisture-permeable stretchable sheet 10. Each elastic filament 13 may extend linearly as long as it does not cross each other, or may extend while meandering.

  The fact that the filaments do not cross each other means that there are almost no intersections. If there is an intersection point, it means that there are a plurality of fibers between the intersection points. However, it is rare that the lengths of the fibers existing between the intersection points coincide with each other industrially. If stretching is performed while the lengths of the fibers existing between the intersections are different, stress is applied only to the shorter fibers contained between the intersections. However, many fibers are not involved in elongation. When compared with fibers of the same weight, the shrinkage force becomes smaller as the number of fiber intersections increases. Therefore, cost is wasted. Considering expansion and contraction only in the vertical direction, if there are fibers in the horizontal direction like a net, the fibers in the horizontal direction are not only useless, but the intersections mentioned above occur, and the fibers in the vertical direction are also used in the same way. The part will occur.

  The direction in which the elastic filament 13 extends may coincide with the flow direction when the sheets 11 and 12 are manufactured, or may be orthogonal to the flow direction when the sheets 11 and 12 are manufactured. When the moisture-permeable stretchable sheet 10 is manufactured according to a preferable manufacturing method to be described later, the extending direction of the elastic filament 13 coincides with the flow direction at the time of manufacturing the sheets 11 and 12.

  The elastic filament 13 is bonded to the sheets 11 and 12 in a substantially non-stretched state. These sheets 11 and 12 are non-stretchable and extendable. Since the elastic filament 13 is bonded to the sheets 11 and 12 in a state where the elastic filament 13 is not stretched, the moisture-permeable stretch sheet 10 of the present embodiment has an advantage that the stretch (relief) does not occur and the stretchability is not easily lowered. is there. Further, for example, when the elastic filament 13 is stretched twice and bonded to the sheets 11 and 12, if it is temporarily returned to 1.3 times the initial value, it can only be stretched up to 1.54 times from this state. . However, when pasting is performed in a non-stretched state, the initial origin when the moisture-permeable stretch sheet is stretched is different, so that the stretchable length of the sheets 11 and 12 or the maximum stretch of the elastic filament 13 is reached. There is an advantage that it can be extended.

  There are the following advantages in joining the elastic filaments 13 to the sheets 11 and 12 in a state where the elastic filaments 13 are not stretched. The moisture-permeable stretch sheet 10 of the present embodiment, for example, joins the substantially non-stretched elastic filament 13 to the non-stretched sheets 11 and 12 to form a wound-up raw sheet (at this time, the elastic filament 13 and non-stretched sheets 11 and 12 joined to 13 are non-stretchable), and the original fabric is drawn out and stretched in another process (for example, tooth gap stretching) to stretch the non-stretched sheets 11 and 12 Manufactured by making possible sheets. In the state of the original fabric, the original fabric is non-stretchable and non-stretchable, so that no external force acts on the elastic filament 13. As a result, there is an advantage that even if the original fabric is stored for a long period of time, relaxation due to elongation does not occur.

  The elastic filament 13 can be a thread-like synthetic rubber thread or natural rubber. Alternatively, it may be obtained by dry spinning (melt spinning) or wet spinning. Among these, in view of a suitable manufacturing method to be described later, the elastic filament 13 is preferably obtained by direct melt spinning without temporarily winding or storing the elastic filament 13.

  The elastic filament 13 is preferably obtained by stretching a molten resin discharged from a nozzle on a spinning line. By stretching, the polymer constituting the elastic filament 13 is molecularly oriented in the longitudinal direction of the elastic filament 13, so that the going / returning ratio at 70% elongation described later is increased and the hysteresis loss is reduced. Further, a thin elastic filament can be obtained by stretching. From this point of view, the elastic filament 13 is preferably stretched 1.1 to 400 times, particularly 4 to 100 times.

  In particular, the elastic filament 13 is preferably formed by being stretched in a state where the elastic resin is melted or softened. This makes it possible to obtain a sufficiently thin filament, and the texture is improved for reasons described later. In addition, the elastic filament 13 is stretched in a state where the elastic resin is melted or softened, so that the elastic filament 13 brought to room temperature after being bonded to the sheets 11 and 12 does not show a force to shrink, and the elastic filament 13 is not It becomes the same state as having joined to each sheet | seat 11 and 12 in the expansion | extension state. Specific operations for stretching in the present embodiment are as follows: (a) A resin as a raw material of the elastic filament 13 is melt-spun to obtain an unstretched yarn, and the elastic filament of the unstretched yarn is heated again to soften the temperature. (B) Operation for stretching in a state higher than (hard segment glass transition temperature Tg), and (b) operation for directly stretching a molten fiber obtained by melt spinning a resin as a raw material of the elastic filament 13 . When the moisture-permeable stretchable sheet 10 is manufactured according to a preferable manufacturing method described later, the elastic filament 13 is obtained by directly stretching a melted fiber obtained by melt spinning.

  The elastic filament 13 obtained by drawing after spinning preferably has a diameter of 10 to 200 μm, particularly 20 to 130 μm. This range is determined in consideration of the texture of the moisture-permeable stretch sheet 10 and the productivity of the elastic filament 13. Specifically, if the diameter of the elastic filament 13 is too large, a step due to the elastic filament 13 is easily perceived when the moisture-permeable stretchable sheet 10 is touched. This step acts negatively on the texture of the moisture-permeable stretchable sheet 10. From this point of view, it is preferable that the elastic filament 13 has a smaller diameter because only the texture of the sheets 11 and 12 is easily perceived. In addition, the elastic filament 13 is preferably thin in order to reduce the light transmittance of the sheets 11 and 12 so as to provide a so-called body fluid color concealing performance. Furthermore, in the elastic expression process by the tooth space roll described later, the diameter of the elastic filament 13 is equal to or less than the tooth-to-tooth clearance between the tooth space rolls. Since the clearance is reduced at a higher point and is 250 μm or less, more preferably 200 μm or less, the elastic filament is less likely to be damaged (cracked or cut) during stretching. The ratio between the diameter of the elastic filament and the clearance is preferably 0.2 to 1, and more preferably 0.2 to 0.5. However, the smaller the elastic filament 13 is, the less easy it is to manufacture. Considering these, the diameter of the elastic filament 13 is preferably within the above-mentioned range.

  From the viewpoint of preventing the above-described step from being generated, the ratio of the diameter in the thickness direction of the elastic sheet 13 of the elastic filament 13 to the thickness of the moisture-permeable elastic sheet 10 is 1 to 30%, particularly 5 to 15%. Is preferred.

  The elastic filament 13 may have a circular cross section, but may be elliptical or flat in some cases. For example, when the moisture-permeable stretchable sheet 10 is manufactured according to the manufacturing method described later, the cross section of the elastic filament 13 tends to be flat. In this case, in the moisture permeable stretch sheet 10, the elastic filament 13 has a flat major axis substantially in the same direction as the plane direction of the moisture permeable stretch sheet 10 and a short axis in the thickness direction of the moisture permeable stretch sheet 10. It is preferable to arrange so as to be substantially in the same direction.

  When the cross section of the elastic filament 13 is flat, the ratio of long axis / short axis (average flatness ratio) is 1.0 to 7.0, particularly 1.1 to 3.0. This is preferable from the viewpoint of increasing the bonding strength between the filament 13 and the constituent materials of the sheets 11 and 12 and the hiding performance of the moisture-permeable stretchable sheet 10. The elastic filaments 13 having a flat cross section are arranged such that the major axis direction thereof substantially coincides with the plane direction of the moisture-permeable stretchable sheet 10. In addition, when the cross section of the elastic filament 13 is flat, the diameter of the elastic filament 13 means what averaged the major axis diameter and the minor axis diameter. The major axis in the elastic filament 13 having a flat shape refers to the length of the longest transverse line on the outer periphery of the elastic filament 13 extracted by microscopic observation. The short axis in the elastic filament 13 refers to the length of the short side when a rectangle having two sides parallel to the long axis determined as described above and circumscribing the outer periphery is drawn. These are measured with respect to five arbitrary elastic filaments, and the average flatness is defined as the average flatness, and the average diameter is defined as the diameter of the elastic filament.

In relation to the thickness of the elastic filament 13, the bonding area of the elastic filament 13 and the first and second sheets 11, 12 is 1 to 30% with respect to the area of the moisture-permeable stretchable sheet 10, especially 2 It is preferable that it is ˜20%, particularly 3 to 15% from the viewpoint of maintaining high moisture permeability (hereinafter, this value is referred to as “bonded area ratio”). The bonding area ratio is calculated from the following equation.
Bonding area ratio [%] = filament diameter [mm] × (1000 ÷ filament pitch [mm]) × 1000 ÷ (1000 × 1000) × 100
The bonded area ratio is the occupied area ratio of the filament as viewed from the plane direction. The above formula is a formula calculated for a sample of 1000 mm × 1000 mm. (1000 ÷ filament pitch) is the number of filaments in a width of 1000 mm, and by multiplying this by the filament diameter and multiplying the length by 1000 mm, the occupied area of the filament is obtained, and this is the sample area of 1000 mm × 1000 mm The divided value is expressed as a percentage.

  The elastic filament 13 is also preferably colored in a color different from the colors of the sheets 11 and 12. As a result, the elastic filament 13 can be seen through the first sheet 11 and / or the second sheet 12, and the moisture-permeable stretchable sheet 10 exhibits a striped pattern. Such an effect becomes more remarkable particularly when the thickness and basis weight of each of the sheets 11 and 12 are within the ranges described later.

  From the viewpoints of the moisture-permeable stretch sheet 10 exhibiting sufficient stretchability, the fabric-like texture, and the design effect as necessary, the pitch of the adjacent elastic filaments 13 ( The distance between the adjacent elastic filaments 13) is 0.1 to 5 mm, particularly 0.4 to 3 mm, and further 0.5 mm to 2 mm, provided that the diameter of the elastic filament 13 is in the above-described range. Is preferred.

  The elastic filament 13 is bonded to the sheets 11 and 12 over its entire length. Here, “joined over the entire length” means that all the portions of the sheets 11 and 12 that are in contact with the elastic filament 13 (the constituent fibers when the sheet 12 is a nonwoven fabric) are the elastic filaments. 13 that the elastic filament 13 and the sheets 11 and 12 are bonded in such a manner that there is no intentionally formed non-bonded portion in the elastic filament 13. To tell. Since the elastic filament 13 is bonded to the sheets 11 and 12 over the entire length, the bonding force between the elastic strand 13 and the sheets 11 and 12 can be sufficiently increased. As a result, even if the moisture-permeable stretchable sheet 10 is stretched, the elastic filament 13 is difficult to peel from the sheets 11 and 12. If the elastic filament 13 is peeled off from the sheets 11 and 12, in the natural state (relaxed state), the elastic filament 13 floats between the sheets 11 and 12, and the moisture-permeable stretchable sheet 10 is wrinkled. It becomes easy to generate | occur | produce and it lacks the sense of unity as the moisture-permeable elastic sheet 10 whole.

  As a mode of joining the elastic filament 13 and each of the sheets 11 and 12, for example, fusion is mentioned. When the moisture-permeable stretchable sheet 10 is manufactured according to a suitable manufacturing method described later, the elastic filament 13 is bonded to the sheets 11 and 12 by fusion bonding. The fusion includes both a state in which the elastic filament 13 and the sheets 11 and 12 are melted and bonded to each other, or a state in which either one is melted and the other bites into the adhesive. According to this method, excessive heat is not applied to the sheets 11 and 12, and the elastic filaments 13 are fused to the sheets 11 and 12 before the elastic filaments 13 obtained by melt spinning are solidified. 11 and 12, only the portion existing around the elastic filament 13 is joined to the elastic filament 13, and the portion located further away from the elastic filament 13 maintains the texture of the sheets 11 and 12. There is an advantage that the texture of the moisture-permeable stretchable sheet 10 is kept good. In this case, an adhesive may be applied as an auxiliary joining means before joining the sheets 11 and 12 and the elastic filament 13. Or after joining each sheet | seat 11,12 and the elastic filament 13, heat processing (steam jet, heat embossing) etc. can also be performed as an auxiliary joining means. When the sheet 12 is a non-woven fabric, mechanical entanglement (needle punch, spun lace) or the like can be performed. However, these auxiliary joining means may damage the texture of the obtained moisture-permeable stretch sheet 10 or damage the elastic filament 13. Therefore, it is preferable to fuse the elastic filament 13 to the sheets 11 and 12 with the heat of fusion. However, in the case where the sheet 12 is made of a nonwoven fabric, the texture of the moisture-permeable stretchable sheet 10 to be obtained is not impaired if a heat treatment consisting of hot air blowing by an air-through method is used as an auxiliary joining means. This is preferable in that a high bonding strength can be obtained.

  The moisture-permeable stretchable sheet 10 can be stretched in the same direction as the direction in which the elastic filament 13 extends. The stretchability of the moisture permeable stretch sheet 10 is expressed due to the elasticity of the elastic filament 13. When the moisture-permeable stretchable sheet 10 is stretched in the same direction as the direction in which the elastic filament 13 extends, the elastic filament 13 and the first and second sheets 11 and 12 extend. When the stretch of the moisture-permeable stretchable sheet 10 is released, the elastic filament 13 contracts, and the first and second sheets 11 and 12 return to the state before stretching as the contraction occurs.

  In the moisture-permeable stretch sheet 10 of the present embodiment, there are no other elastic filaments bonded in a state orthogonal to the elastic filaments 13. Therefore, even if the moisture-permeable stretchable sheet 10 is stretched in the same direction as the direction in which the elastic filament 13 extends, the stretchable sheet 10 stretches with little width shrinkage. That is, in the stretched state, the moisture-permeable stretchable sheet 10 has a substantially uniform width in the longitudinal direction. As a result, handling properties when the moisture-permeable stretchable sheet 10 is conveyed and processed in the stretched state are improved. Moreover, when the moisture-permeable stretchable sheet 10 is used as, for example, a back sheet of a disposable diaper, it is effectively prevented that the diaper is slipped or wrinkled during wearing. In addition, considering the configuration of the diaper and the movement of the user, uneven expansion occurs in the width direction, but there is almost no shrinkage in the width, and it is effective that the diaper is displaced or wrinkled. To be prevented. From this viewpoint, it is preferable that the moisture-permeable stretch sheet 10 has a width shrinkage ratio of 1% to 10%, particularly 1% to 5% of the width before stretching when the sheet is stretched 1.5 times. . The width reduction can be calculated as (1−width after extension ÷ width before extension) × 100. The width after stretching is measured as follows. The sample is cut out with a width of 50 mm so that the length direction is substantially along the flow direction (within an angle difference of 15 degrees or less). The length is over 150 mm. While maintaining the width of the sample at 50 mm, both ends in the longitudinal direction of the sample are gripped at a gripping interval of 150 mm. At this time, care is taken so that the sample does not sag in the longitudinal direction and does not stretch. From this state, the width of the central portion in the length direction of the sample when the grip interval is extended to 1.5 times is measured, and the value is taken as the width after extension.

  FIG. 2 shows a photograph of the moisture-permeable stretch sheet 10 according to one embodiment of the present invention taken from the first sheet 11 side in its natural state (relaxed state). The moisture-permeable stretchable sheet 10 uses a stretchable non-stretchable moisture-permeable film as the first sheet 11 and uses a stretchable non-stretchable nonwoven fabric as the second sheet 12. Reference numeral 13 denotes an elastic filament. In the figure, a direction X indicated by an arrow indicates a direction in which the elastic filament 13 extends. The embodiment shown in FIG. 2 is a form that remarkably develops when tooth gap extension is used in the elastic expression treatment process described later in the manufacturing process of the moisture-permeable stretchable sheet 10. In the moisture-permeable stretch sheet 10 shown in FIG. 2, the relatively transparent portion 15 and the portion 14 that is whitened and non-transparent and has the wrinkle-like unevenness 14 a are formed in a direction orthogonal to the X direction. Each extends and is alternately located along the X direction. The ridge-like unevenness 14a in the portion 14 extends in a direction orthogonal to the X direction. As will be described later, the part 15 is a part in contact with teeth at the time of tooth gap extension, and the part 14 is a part where a part between teeth is extended.

  In detail, in the natural state, in the portion 14 of the stretchable sheet 10, minute protrusions and recesses extending in the same direction (direction orthogonal to the X direction) are alternately arranged on one surface and the other surface. Is formed. At the position of the convex portion and the concave portion on one surface, the concave portion and the convex portion on the other surface are located.

  Next, the constituent materials of the first and second sheets 11 and 12 and the elastic filament 13 constituting the moisture-permeable stretchable sheet 10 will be described. The first sheet 11 is made of a non-stretchable moisture permeable film. This non-stretchable moisture permeable film is obtained by, for example, melt-molding a resin composition obtained by kneading a material incompatible with the resin into a thermoplastic resin into a film shape, and the obtained film is uniaxial or biaxial. It is made porous by axial stretching. Examples of the thermoplastic resin that can be used include polyolefins such as polyethylene, polypropylene, and olefin copolymers. Examples of substances that are not compatible with thermoplastic resins include calcium carbonate, gypsum, calcium sulfate, calcium phosphate, magnesium carbonate, magnesium sulfate, hydrated silicic acid, anhydrous silicic acid, soda ash, sodium chloride, sodium sulfate, and barium sulfate. Inorganic fillers such as talc, clay, various cements, volcanic ash, shirasu, titanium oxide, iron oxide and carbon black, various metal powders, other inorganic substances, and organic metal salts mainly composed of inorganic substances. Moreover, polymers such as thermosetting resins such as phenol resin, epoxy resin, and sodium polyacrylate, or resins having a melting temperature higher than the molding temperature of the thermoplastic resin are mentioned. These substances are desirably used as a granular material having an average particle diameter of 50 μm or less, preferably 0.05 to 30 μm, particularly about 0.1 to 5 μm. The blending ratio of the thermoplastic resin and the substance is preferably 50 to 400 parts by weight, more preferably 60 to 300 parts by weight with respect to 100 parts by weight of the thermoplastic resin.

  The first sheet 11 preferably has a moisture permeability (JIS Z0208) of 0.4 to 6 g / (100 cm 2 · hr), particularly 0.8 to 4 (100 cm 2 · hr). The first sheet 11 preferably has a water pressure resistance (JIS L1092 A method: low water pressure method) of 5 cm or more, more preferably 10 to 500 cm, and even more preferably 50 to 200 cm. . Further, the first sheet 11 made of a moisture permeable film has a thickness of 5 to 100 μm, particularly 7 to 50 μm, particularly 10 to 40 μm, provided that the moisture permeability and the water pressure resistance are within the above-mentioned ranges. preferable. The thickness measurement method is the same as the thickness measurement method when the second sheet 12 is a non-woven fabric (this measurement method will be described later).

As described above, the second sheet 12 is an extensible sheet. Examples of the stretchable sheet include non-stretchable paper (mounting paper), non-stretchable nonwoven fabric, and a second non-stretchable moisture permeable film. When the second sheet 12 is made of paper, paper containing plant fibers such as wood pulp and natural fibers such as animal fibers, or paper containing synthetic fibers can be used. These papers are generally moisture permeable. These papers are manufactured by a wet method or a dry method. The basis weight of the paper used as the second sheet 12, depending on the specific application of the moisture-permeable stretch sheet 10, 5 to 50 g / m ^2, can be appropriately selected from the range in particular of 10 to 30 g / m ² .

  When the 2nd sheet | seat 12 consists of a 2nd non-stretchable moisture-permeable film, the same kind as a 1st non-stretchable moisture-permeable film, or a different kind can be used as this film. Therefore, for the details of the second non-stretchable moisture-permeable film, the above description of the first non-stretchable moisture-permeable film is applied as appropriate. The same type here means a non-stretchable moisture permeable film manufacturing process, the type of resin constituting the non-stretchable moisture permeable film, and the thickness and basis weight of the non-stretchable moisture permeable film are all the same. It means between wet films. When at least one of these is different, it is said to be a different kind of non-stretchable moisture permeable film.

  When the 2nd sheet | seat 12 consists of a nonwoven fabric, a substantially inelastic fiber is used as a fiber which comprises this nonwoven fabric. Examples thereof include fibers made of polyethylene (PE), polypropylene (PP), polyester (PET or PBT), polyamide, and the like. The fibers constituting the nonwoven fabric may be short fibers or long fibers, and may be hydrophilic or water repellent. Further, core-sheath type or side-by-side composite fibers, split fibers, irregularly shaped cross-section fibers, crimped fibers, heat-shrinkable fibers, and the like can also be used. These fibers can be used singly or in combination of two or more. The nonwoven can be a continuous filament or short fiber nonwoven. In particular, from the viewpoint of making the moisture-permeable stretch sheet 10 thick and bulky, the nonwoven fabric is preferably a nonwoven fabric of short fibers. When the moisture-permeable stretchable sheet 10 is used as a member that comes into contact with the skin, a short fiber nonwoven fabric having a good texture may be used on the skin contact side, and a high-strength continuous filament nonwoven fabric may be used on the opposite surface.

  The non-woven fabric is preferably composed of two or more components of a low melting point component and a high melting point component. In that case, the constituent fibers are joined at fiber intersections by at least thermal fusion of the low melting point components. As the core-sheath type composite fiber composed of two or more components of a low melting point component and a high melting point component, those having a core of high melting point PET, PP and a sheath of low melting point PET, PP, PE are preferable.

The thickness of the nonwoven fabric is preferably 0.05 to 5 mm, more preferably 0.1 to 1.0 mm, and still more preferably 0.15 to 0.5 mm. The thickness is measured by observing the cross section of the moisture-permeable stretchable sheet 10 with a load of 0.5 cN / cm ² at a magnification of 50 to 200 times with a microscope, and obtaining the average thickness in each field of view. It can be obtained as an average value of the thickness of the visual field. The total thickness of the moisture-permeable stretchable sheet 10 is obtained by measuring the distance between the flat plates. The basis weight of the nonwoven fabric is preferably ³ to 100 g / m ² , particularly preferably 10 to 30 g / m ² , from the viewpoints of texture, thickness, and design properties.

  The nonwoven fabric is preferably made of substantially inelastic fibers from the viewpoints of texture, stickiness, and the like. The proportion of inelastic fibers in the nonwoven fabric is preferably 70% by weight or more, particularly 90% by weight or more, and particularly preferably 100% by weight. Moreover, the substantially inelastic fiber may contain a small amount of elastic resin in the inelastic resin. In this case, the proportion of the inelastic resin is preferably 70% by weight or more, more preferably 90% by weight, and still more preferably 100% by weight.

  In particular, it is preferable to use a non-elastic fiber whose fiber thickness is not uniform in the length direction (hereinafter, this fiber is referred to as an indefinite fiber). That is, indefinite-diameter fibers have a large fiber cross-sectional area (diameter) and a small part when viewed along the length direction. In the indefinite fiber, the diameter (cross-sectional area) may continuously change from the smallest part to the largest part. Alternatively, the diameter (cross-sectional area) of the fiber may change in a substantially step shape, as in the necking phenomenon observed in the undrawn yarn drawing process. FIG. 3 shows an example of an inelastic fiber in which the fiber diameter (cross-sectional area) is changed in a substantially step shape.

  The inelastic fiber is made from a fiber having a constant fiber diameter and a high elongation (for example, the maximum elongation of the fiber is 80 to 800%, particularly 120 to 650%). It is preferable at the point obtained. The elongation of the fiber conforms to JIS L-1015, based on the measurement environment temperature and humidity 20 ± 2 ° C., 65 ± 5% RH, tensile tester gripping distance 20 mm, tensile speed 20 mm / min. To do. In addition, when collecting fibers from an already manufactured non-woven fabric and measuring the elongation, when the gripping interval cannot be 20 mm, that is, when the length of the fiber to be measured is less than 20 mm, the gripping interval is set. Measure by setting to 10 mm or 5 mm.

  The high-stretch fiber is preferably a low-stretch inelastic fiber. When the moisture-permeable stretchable sheet 10 according to the present embodiment is manufactured using low-stretched inelastic fibers as a raw material according to the manufacturing method described later, a thin portion is generated in the fibers by stretching the low-stretched fibers in the elastic expression treatment. The indefinite diameter fiber mentioned later is formed. As a result, in the elastic expression treatment of the moisture-permeable stretch sheet 10 of the present embodiment, the nonwoven fabric is changed into a shape that is easily stretched structurally, but the entire nonwoven fabric structure is easily stretched by stretching the fibers. Therefore, it is possible to minimize the breakage of the joint points between the amorphous fibers and the joint points between the nonwoven fabric 12 and the elastic filaments 13, and the strength of the moisture-permeable stretch sheet 10 while maintaining the stretch performance. Can be high. That is, the moisture-permeable stretch sheet 10 having both high elongation and high strength is obtained. Further, in the elastic expression treatment, the bonding between the indefinite fibers is less likely to be destroyed, which also has the effect of making the nonwoven fabric less likely to become fluffy. This is advantageous in terms of improving the appearance of the moisture-permeable stretchable sheet 10 of the present embodiment.

  The non-constant fiber preferably has an inter-fiber fusion point strength higher than the strength at 100% elongation of the non-constant fiber. Thereby, in the elastic expression treatment process when manufacturing the moisture-permeable elastic sheet 10, when the moisture-permeable elastic sheet 10 before the elastic expression treatment is stretched and subjected to the elastic expression treatment, the fibers of the nonwoven fabric 12 before the elastic expression treatment are processed. From the point that it becomes difficult for breakage of the fusion point to occur and the strength of the moisture-permeable stretch sheet 10 obtained through the elastic development treatment step is less likely to be lower than the strength of the moisture-permeable stretch sheet 10 before the elasticity development treatment. preferable. The fusion point strength is measured according to the description in paragraph [0040] of Japanese Patent Application Laid-Open No. 2004-218183 relating to the previous application of the present applicant. The strength at 100% elongation is measured using a tensile tester under conditions of a distance between chucks of 20 mm and a tensile speed of 20 mm / min.

  The low-stretched inelastic fibers described above include both fibers drawn at a low draw ratio after spinning and unstretched fibers, that is, unstretched fibers. As the low-stretched fiber, it is preferable to use a fiber having a high elongation of 80 to 800%, particularly 120 to 650% as described above. By using a low-stretched fiber having an elongation in this range, the fiber is successfully stretched by a stretching apparatus 22 shown in FIG. The fiber diameter of the low-stretched fiber is preferably 10 to 35 μm, particularly preferably 12 to 30 μm.

  As described above, the non-constant diameter fiber is preferably made from a low-stretched fiber having a constant fiber diameter as a raw material. In this case, the low-stretched fiber may be a fiber made of a single raw material, or a composite fiber using two or more raw materials, such as a core-sheath type composite fiber or a side-by-side type composite fiber. Good. Considering the ease of joining the indefinite diameter fibers and the ease of joining the nonwoven fabric 12 and the elastic filaments 13, it is preferable to use a composite fiber. In the case of the core-sheath type composite fiber, the core is preferably polyester (PET or PBT) or polypropylene (PP), and the sheath is preferably low melting point polyester (PET or PBT), polypropylene (PP) or polyethylene (PE). In particular, when these composite fibers are used, when the elastic filament 13 contains a polyolefin-based elastomer, thermal fusion between the elastic filament 13 and the constituent fibers of the nonwoven fabric 12 becomes strong and delamination hardly occurs.

  The non-constant diameter fiber may be a short fiber such as a staple fiber, or may be a long fiber such as a continuous filament. In view of a suitable manufacturing method of the moisture-permeable stretch sheet 10 described later, it is preferable to use short fibers. The indefinite fiber may be hydrophilic or water repellent.

  The nonwoven fabric 12 may be composed of only indefinite diameter fibers, or may contain other inelastic fibers having a constant diameter in addition to the indefinite diameter fibers. Other inelastic fibers include those mentioned above. When the nonwoven fabric 12 contains non-elastic fibers having other fixed diameters in addition to the non-constant diameter fibers, the blending amount of the other non-elastic fibers may be 1 to 30% by weight, particularly 5 to 20% by weight. preferable.

  As described above, the elastic filament 13 is made of, for example, an elastic resin such as a thermoplastic elastomer or rubber. In particular, when a thermoplastic elastomer is used as a raw material for the elastic resin, melt spinning using an extruder is possible in the same manner as a normal thermoplastic resin, and the filaments thus obtained are easy to heat-seal, It is suitable for the elastic sheet of this embodiment. Examples of the thermoplastic elastomer include SBS (styrene-butadiene-styrene), SIS (styrene-isoprene-styrene), SEBS (styrene-ethylene-butadiene-styrene), and SEPS (styrene-ethylene-propylene-styrene). And olefin elastomers (ethylene-based α-olefin elastomers, propylene-based elastomers copolymerized with ethylene / butene / octene), polyester-based elastomers, and polyurethane-based elastomers. These can be used individually by 1 type or in combination of 2 or more types. A core-sheath type or side-by-side type composite fiber made of these resins can also be used. In particular, use of a styrene-based elastomer, an olefin-based elastomer, or a combination thereof is preferable in terms of moldability, elastic properties, and cost of the elastic filament 13.

  Next, the preferable manufacturing method of the moisture-permeable elastic sheet 10 of this embodiment is demonstrated, referring FIG. In this manufacturing method, a large number of molten elastic filaments 13 spun from the spinning nozzle 16 are drawn and stretched at a predetermined speed, and the elastic filaments 13 do not cross each other before the elastic filaments 13 are solidified. The elastic filaments 13 are fused to the sheets 11 and 12 so as to be arranged in one direction, and then the composite 19 to which the elastic filaments 13 are fused is subjected to an elastic expression process along the extending direction of the elastic filaments 13. Elasticity is imparted to the composite 19.

  The spinning nozzle 16 is provided in the spinning head 17. The spinning head 17 is connected to an extruder. Resin can also be supplied to the spinning head 17 via a gear pump. The elastic resin melt-kneaded by the extruder is supplied to the spinning head 17. The spinning head 17 has a large number of spinning nozzles 16 arranged in a straight line. The spinning nozzle 16 is disposed along the width direction of the first and second sheets 11 and 12. The interval between the adjacent spinning nozzles 16 corresponds to the interval between the elastic filaments 13 in the intended moisture-permeable stretch sheet 10. The spinning nozzle 16 is usually circular, and its diameter affects the diameter of the elastic filament 13 and the draw ratio. From this viewpoint, the diameter of the spinning nozzle 16 is preferably 0.1 to 2 mm, particularly preferably 0.2 to 0.6 mm. For the purpose of increasing the bonding strength with the sheets 11 and 12, the purpose of increasing the spinnability of the elastic filament 13, and the purpose of improving the stretch characteristics of the moisture-permeable stretch sheet 10, the elastic filament 13 is in a composite form (side-by-side, core sheath, Sea-island structure). Specifically, it is preferable to combine a PP elastomer resin and a styrene elastomer resin.

  The melted elastic filaments 13 spun together with the first sheet 11 and the second sheet 12 fed from the original fabric at the same speed, and are sandwiched between the sheets 11 and 12 and taken up at a predetermined speed. It is done. The take-up speed of the elastic filament 13 coincides with the feeding speed of both sheets 11 and 12. The take-up speed of the elastic filament 13 affects the diameter and the draw ratio of the elastic filament 13. The tension generated in the elastic filament 13 by stretching prevents the elastic filament 13 from being disturbed due to wind or static electricity when the elastic filament 13 is bonded to the sheets 11 and 12. Thereby, the elastic filaments can be arranged in one direction without crossing each other. From these viewpoints, the drawing speed of the elastic filament 13 is 1.1 to 400 times, particularly 4 to 100 times, more preferably 10 to 80 times the resin discharge speed in the spinning nozzle hole. It is preferable to adjust.

  The elastic filament 13 merges with the first and second sheets 11 and 12 before solidification, that is, in a state capable of being fused. As a result, the elastic filament 13 is fused to these sheets 11 and 12 while being sandwiched between the first and second sheets 11 and 12. That is, the elastic filament 13 is pulled and stretched while the elastic filament before solidification is fused to the conveyed sheets 11 and 12. When the elastic filament 13 is fused, heat is not applied to the first and second sheets 11 and 12 from the outside. That is, the elastic filament 13 and the two sheets 11 and 12 are fused only by the heat of fusion caused by the elastic filament 13 that can be fused. As a result, only the site | part which exists in the circumference | surroundings of the elastic filament 13 among both the sheets 11 and 12 fuse | melts with this elastic filament, and the site | part which exists in the position away from it does not fuse | melt. As a result, since the heat applied to both the sheets 11 and 12 is kept to a minimum, the good texture inherent to the sheets 11 and 12 themselves is maintained. Thereby, the texture of the moisture-permeable elastic sheet 10 obtained becomes favorable.

  Until the spun elastic filament 13 merges with the first and second sheets 11 and 12, the elastic filament 13 is stretched and molecules are oriented in the stretching direction. Also, the diameter is reduced. Due to the molecular orientation, an elastic filament 13 having a small strength going / return ratio (hysteresis) at 70% elongation can be obtained. From the viewpoint of sufficiently stretching the elastic filament 13 and from the viewpoint of preventing the elastic filament 13 from being broken, a wind (hot air or cold air) of a predetermined temperature is blown onto the spun elastic filament 13 to set the temperature of the elastic filament 13. You may adjust.

  The stretching of the elastic filament 13 may be not only stretching in the molten state of the raw material resin (melt stretching), but also stretching in the softened state (softening stretching) in the cooling process. The molten state is a state in which the resin flows when an external force is applied. The melting temperature of the resin is measured as a peak temperature of Tan δ by viscoelasticity measurement (for example, measured by adding vibration strain in the rotational direction to a resin sandwiched between circular parallel plates). In order to prevent thread breakage when using an elastic resin, it is preferable to secure a long stretch section. Similarly, the melting temperature of the elastic resin is preferably 130 to 300 ° C. so that the yarn breakage does not occur. Furthermore, the melting temperature is preferably 220 ° C. or less from the viewpoint of the heat resistance of the elastic resin. The molding temperature (die temperature) of the elastic filament 13 is preferably + 50 ° C. or more of the melting temperature of the raw material resin in order to increase the fluidity of the resin and improve the moldability, and is preferably + 110 ° C. or less for heat resistance. The softening temperature is measured as the Tg temperature in the viscoelastic property of the measurement sample of the elastic resin in sheet form. The range from the softening temperature to the melting temperature is called a softened state. Moreover, the state of temperature lower than softening temperature is called solidified state. The softening temperature is preferably 60 ° C. or higher, more preferably 80 ° C. to 180 ° C., from the viewpoint of the growth of elastic resin crystals during storage of the moisture permeable stretch sheet 10 and the decrease in stretch properties of the moisture permeable stretch sheet 10 due to body temperature. preferable.

  The temperature of the elastic filament 13 when the elastic filament 13 and the sheets 11 and 12 are joined is preferably 100 ° C. or higher in order to ensure fiber fusion. More preferably, it is 120 degreeC or more, More preferably, it is 140 degreeC or more. Further, from the viewpoint of obtaining the moisture-permeable stretch sheet 10 having a good stretch property while maintaining the shape of the elastic filament 13, the temperature of the elastic filament is preferably 180 ° C. or lower. More preferably, it is 160 degrees C or less. As a result, the optimum filament temperature is in the range of 120 to 160 ° C, more preferably 140 to 160 ° C. The bonding temperature is observed using a film made of a modified polyethylene or a modified polypropylene having a melting point different from the melting point of the elastic resin constituting the elastic filament as a laminate base material to be bonded to the elastic filament 13. Can be measured. At this time, if the elastic filament and the laminate base material are fused, the joining temperature is equal to or higher than the melting point of the laminate base material.

  At the time of joining the elastic filament 13 and the first and second sheets 11, 12, the elastic filament 13 is substantially in a non-stretched state (a state in which it does not shrink when an external force is removed). Further, when the elastic filaments 13 are joined with the sheets 11 and 12, the elastic filaments 13 are arranged in one direction without crossing each other. Then, the elastic filament 13 is merged with the first and second sheets 11 and 12, and the elastic filament 13 is sandwiched between the sheets 11 and 12, and these three members are clamped by a pair of nip rolls 18 and 18. . The condition of the clamping pressure affects the texture of the stretchable sheet 10 obtained. If the pinching pressure is too large, the elastic filament 13 is likely to bite into both the sheets 11 and 12, and the texture of the moisture-permeable stretchable sheet 10 obtained due to the elastic filament 13 tends to decrease. From this point of view, the clamping pressure by the nip rolls 18 and 18 is sufficient for the elastic filament 13 to contact both the sheets 11 and 12, and an excessively high clamping pressure is not required.

  Another condition for the clamping pressure by the nip roll 18 is the temperature of the nip roll 18. As a result of the study by the present inventors, it is better not to heat the nip roll 18 in a heated state (that is, to leave it to the result), or to perform the pressing while cooling, a better texture. It has been found that a moisture-permeable stretch sheet 10 can be obtained. When cooling the nip roll 18, it is preferable to use a coolant such as cooling water and adjust the temperature so that the surface setting temperature of the nip roll 18 is 10 to 50 ° C.

  In this way, a composite 19 in which the elastic filament 13 is sandwiched between the two sheets 11 and 12 is obtained. When the sheets 11 and 12 that are inherently extensible are used, the composite 19 becomes the moisture-permeable stretchable sheet 10 itself. On the other hand, when the sheets 11 and 12 that are not inherently extensible are used, the composite body 19 including the sheets 11 and 12 is elastically treated along the direction in which the elastic filament 13 extends, An operation of imparting stretchability to the composite 19 is performed. In the present manufacturing method, this operation is performed using an elastic expression processing device 22 having a pair of tooth space rolls 20 and 21 in which teeth and roots are alternately formed in the circumferential direction, and the composite 19 is moved in the conveying direction. That is, it is performed by performing an elastic expression process along the extending direction of the elastic filament 13.

  The elastic expression processing device 22 has a known lifting mechanism (not shown) for vertically displacing the pivot portion of one or both of the tooth gap rolls 20 and 21, and the interval between the tooth gap rolls 20 and 21 can be adjusted. It has become. In this manufacturing method, each tooth gap roll 20 and 21 is inserted freely between the teeth of one tooth gap roll 21 and the tooth of the other tooth gap roll 21 is one tooth. It combines so that it may be loosely inserted between the teeth of the groove roll 20, and the composite body 19 is inserted between the both tooth groove rolls 20 and 21 of the state, and this is elastically processed.

  In the elastic expression processing device 22, both the pair of tooth groove rolls 20 and 21 may be driven by a driving source (co-rotating roll), and only one tooth groove roll 20 or 21 is driven by the driving source. It may come to drive (rotating roll).

  FIG. 5 schematically shows a state in which the composite 19 is subjected to an elastic expression process. When the composite 19 passes between the tooth gap rolls 20 and 21, the composite 19 is in a region that contacts the teeth 23 and 24 of the tooth gap rolls 20 and 21 (between P 3 and P 2 and between P 1 and P 4). Is hardly stretched. On the other hand, in the region (between P2 and P1) pressed toward the tooth surface of the tooth 23 of the tooth space roll 20 that is the driven roll by the tooth surface of the tooth 24 of the tooth space roller 21 that is the driving roll. The two teeth 20 and 21 are greatly stretched. Further, in the region (between P4 and P3) that is separated from the tooth 23 of the tooth space roll 20 by the tip of the tooth 24 of the tooth space roll 21, it is not as large as the region (between P2 and P1), but is greatly stretched. The As a result, the portion 14 shown in FIG. 2 described above that is whitened and non-transparent and has the ridge-like unevenness 14a is formed in the portions corresponding to between P2 and P1 and between P4 and P3.

  The composite 19 is hardly stretched as described above in the region (between P3 and P2 and between P1 and P4) in contact with the tips of the teeth 23 and 24 of the tooth gap rolls 20 and 21, but the teeth 23 and 24 are as described above. Is pushed in the radial direction, that is, in the thickness direction of the composite 19, so that it becomes thinner in the thickness direction. As a result, the above-described relatively transparent portion 15 shown in FIG. 2 is formed at portions corresponding to between P3-P2 and between P1-P4. However, because the region (between P3 and P2) and the region (between P1 and P4) are in the opposite direction, the thinning direction is the opposite direction.

  When the sheet 12 is made of a non-woven fabric including low-stretched fibers, the stretching force by the tooth gap rolls 20 and 21 mainly acts on the stretching of the low-stretched fibers, and is applied to the joint portion between the sheets 11 and 12 and the elastic filament 13. Does not apply excessive force. As a result, the composite 19 can be efficiently stretched while preventing breakage of the bonded portion and separation of the sheets 11, 12 and the elastic filament 13. In addition, as shown in FIG. 6, the stretching causes the nonwoven fabric sheet 12 to be sufficiently stretched without breaking the bonding between the fibers, whereby the sheet 12 inhibits free expansion and contraction of the elastic filament 13. Is greatly reduced. As a result, according to the present production method, the moisture-permeable stretch sheet 10 having high strength and high stretchability and good appearance with less tearing and fuzzing can be efficiently produced. In FIG. 6, the thickness of the inelastic fiber generated by stretching is uniformly expressed for convenience.

  As described above, when low-stretched fibers are included in the sheet 12 made of nonwoven fabric, the fibers are successfully stretched, and the joint between these fibers is not broken by stretching. Can be suppressed as much as possible.

  The composite body 19 is elastically treated by the pair of tooth space rolls 20 and 21 to obtain the intended moisture-permeable stretchable sheet 10. After the obtained moisture-permeable stretch sheet 10 passes through the tooth gap rolls 20 and 21, the stretched state in the MD direction is quickly released by its own shrinkage restoring force. As a result, the moisture-permeable stretchable sheet 10 is generally restored in length in the transport direction. Thereby, in the extended state, the high basis weight portions 14 and the low basis weight portions 15 are alternately arranged in the extending direction of the elastic filaments 13. When the stretched state is released, the stretched state may be completely released, or the stretched state may be released in a state where a certain stretched state is maintained as long as stretchability is exhibited.

  By the elastic expression processing, the thickness of the moisture-permeable stretchable sheet 10 is increased 1.1 times to 4 times, particularly 1.3 times to 3 times the thickness of the composite 19 before the elastic expression processing. Is preferred. As a result, the sheet 12 becomes more bulky, the touch is good, and the cushioning property is good.

  The moisture-permeable stretch sheet 10 thus obtained is stretched 70% along the direction in which the elastic filaments 13 extend (170% stretched based on the original length of the moisture-permeable stretch sheet 10 before stretching). ), A load A when returned to a length of up to 130% (hereinafter also referred to as 30% return strength) and a load B when extended along the direction in which the elastic filament 13 extends (hereinafter referred to as 30%). The ratio (A / B) to the travel strength) is preferably 10% or more, particularly 25% or more, from the viewpoint of sufficient stretch properties. A is preferably 10 cN / 50 mm or more, more preferably 20 cN / 50 mm or more, and particularly preferably 35 cN / 50 mm or more from the viewpoint of expression of sufficient stretch properties.

Moreover, it is preferable that the moisture permeability stretchable sheet 10 has a moisture permeability (JIS Z0208) of 0.4 to 6 g / (100 cm ² · hr), particularly 0.8 to 4 (100 cm ² · hr). Moreover, it is preferable that the moisture-permeable stretchable sheet 10 is non-permeable, and the water pressure resistance (JIS L1092 A method: low water pressure method) is preferably 5 cm or more, particularly 10 to 500 cm, and particularly preferably 50 to 200 cm.

Furthermore, although depending on a specific use, the moisture permeable stretch sheet 10 preferably has an overall basis weight of 10 to 150 g / m ² , particularly 25 to 60 g / m ² . Regarding the thickness of the stretchable sheet 10, it is preferably 0.05 to 5 mm, particularly preferably 0.5 to 2 mm. The thickness of the moisture-permeable stretchable sheet 10 is measured by the same method as the measurement of the thickness of each of the sheets 11 and 12 described above.

The moisture-permeable elastic sheet 10 of this embodiment is suitably used as a back sheet for various absorbent articles including disposable diapers and sanitary napkins. Moreover, in the said absorbent article, it uses suitably also for the site | part which wants to provide a stretching property, water impermeability, and moisture permeability. For example, it is suitably used as a panel material for disposable diapers or a wing material for sanitary products. In addition to this application, it is also suitably used for various applications such as medical disposable clothing, cleaning sheets, eye patches, masks, bandages and the like. The moisture-permeable elastic sheet 10 is preferably used as a constituent material for absorbent articles such as sanitary napkins and disposable diapers. Examples of the constituent material include a liquid-permeable sheet (including a surface sheet and a sublayer) positioned on the skin side of the absorbent body, a sheet constituting an outer surface of a disposable diaper, a waistline part, a waist part, a leg Examples thereof include a sheet for imparting elastic stretchability to the surrounding portion and the like. It can also be used as a sheet or the like for forming a napkin wing. Moreover, even if it is a site | part other than that, it can be used for the site | part etc. which want to provide a stretching property. The basis weight and thickness of the stretchable sheet 10 can be appropriately adjusted according to the specific application. For example, when used as a constituent material of an absorbent article, it is desirable that the basis weight is about 20 to 60 g / m ² and the thickness is about 0.5 to 1.5 mm.

  Next, 2nd and 3rd embodiment of this invention is described, referring FIG.7 and FIG.8. Regarding the points that are not particularly described with respect to these embodiments, the above-described description with respect to the first embodiment is appropriately applied. 7 and 8, the same members as those in FIG. 1 are denoted by the same reference numerals.

  In the embodiment shown in FIG. 7, an elastic film 13 </ b> A having moisture permeability is disposed between the first and second sheets 11 and 12. The elastic film 13A has the same shape as the first and second sheets 11 and 12. Therefore, in the moisture-permeable elastic sheet 10 of the present embodiment, there is no portion where the first sheet 11 and the second sheet 12 are in direct contact. However, the elastic film 13A may be one in which one or two or more through holes are formed, and the first sheet 11 and the second sheet 12 may be in direct contact with each other at the position of the through holes.

  The elastic film 13A has moisture permeability as described above. As such an elastic film 13A, for example, a non-porous moisture-permeable elastic film made of a block copolymer polyester resin composed of a hard component and a soft component (see Japanese Patent Application Laid-Open No. 2004-305711) can be mentioned. Further, for example, non-porous materials described in JP-A-7-70936, JP-A-6-134000, JP-B-6-67604, JP-A-1-141669, JP-B-5210104, etc. A moisture-permeable urethane-based elastomer or Soflan palm (trade name) manufactured by Toyo Tire & Rubber Co., Ltd. can be used. Furthermore, for example, non-porous moisture-permeable ester elastomers described in JP-A No. 51-111290 and Frekuma (trade name) manufactured by Nippon Synthetic Chemical Co., Ltd. can be used.

The elastic film 13A preferably has a moisture permeability (JIS Z0208) of 0.4 to 6 g / (100 cm ² · hr), particularly 0.8 to 4 (100 cm ² · hr). Further, the first sheet 11 preferably has a water pressure resistance (JIS L1092 A method: low water pressure method) of 5 cm or more, particularly 10 to 500 cm, particularly 50 to 200 cm. Moreover, it is preferable from the viewpoint of obtaining the moisture-permeable stretch sheet 10 having sufficient stretchability that the elongation before joining of the elastic film 13 is 50 to 500%, particularly 80 to 400%. The elongation of the elastic film 13A is measured by a tensile tester according to the following procedure. A rectangular test piece having a size of 50 mm in the longitudinal direction at the time of manufacturing the elastic film 13A and 50 mm in a direction perpendicular thereto is cut out. The distance between chucks is set to 25 mm (the test piece is a tensile test), and the test piece is attached to the tensile tester. The test piece is stretched in the longitudinal direction at a speed of 300 mm / min. The elongation at break of the test piece is defined as the elongation of the elastic film 13A. The measurement environment was 20 ± 2 ° C. and humidity 65 ± 5% RH. As a tensile tester, a tensile tester AG-1kNIS manufactured by Shimadzu Corporation was used.

  The moisture-permeable stretch sheet 10 of this embodiment can be manufactured by extruding an elastic resin from the spinning head 17 in the form of a film in the apparatus shown in FIG. 4 used in the first embodiment.

  According to this embodiment, there exists an advantage that it is possible to provide elasticity to both the longitudinal direction at the time of manufacture of elastic film 13A, and the direction orthogonal to it.

  A moisture-permeable stretch sheet 10 shown in FIG. 8 uses an elastic band 13B made of a film instead of the elastic filament 13 in the moisture-permeable stretch sheet of the first embodiment. The elastic strip 13B is essential to have elasticity, but unlike the elastic film 13A used in the second embodiment, it is not essential to have moisture permeability. However, it is not prevented at all that the elastic band 13B has moisture permeability. Therefore, as the material of the elastic band 13B, any of the material of the elastic filament 13 used in the first embodiment and the material of the elastic film 13A used in the second embodiment can be used.

  Each elastic strip 13B has a substantially constant width in the extending direction. This width can be appropriately determined according to the specific application of the moisture-permeable stretchable sheet 10. When the moisture-permeable stretch sheet 10 is used as, for example, a back sheet of an absorbent article, the width is preferably 1 to 200 mm, particularly 5 to 100 mm, and more preferably 10 to 50 mm. The width of each elastic strip 13B may be the same or different depending on the specific application of the moisture-permeable stretch sheet 10.

  The elastic strips 13B are separated from each other in the direction orthogonal to the extending direction, and the first sheet 11 and the second sheet 12 are in direct contact with each other between the adjacent elastic strips 13B. Alternatively, the elastic strip 13B may be one in which one or more through holes are formed, and the first sheet 11 and the second sheet 12 may be directly provided at the position of the through holes. In any case, the pitch P between the adjacent elastic strips 13B can be appropriately determined according to the specific application of the moisture-permeable stretch sheet 10. When using the moisture-permeable elastic sheet 10 as a back sheet of an absorbent article, for example, the pitch P is preferably 3 to 500 mm, particularly 6 to 300 mm, and more preferably 11 to 100 mm. The pitch P may be the same or different depending on the specific application of the moisture-permeable stretch sheet 10.

  The moisture-permeable stretch sheet 10 of this embodiment can be manufactured by extruding an elastic resin from the spinning head 17 in a band shape in the apparatus shown in FIG. 4 used in the first embodiment.

  According to the present embodiment, there is an advantage that the balance between moisture permeability and stretchability can be appropriately controlled by the dimensions and arrangement (width and pitch) of the elastic band-like body.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the embodiment shown in FIG. 1, all the elastic filaments 13 have the same diameter and are arranged at an equal pitch. Therefore, the elongation stress is the same regardless of the portion of the moisture-permeable stretchable sheet 10. However, instead of this, the moisture-permeable stretchable sheet may be configured to include two or more regions having different extension stresses in the extension direction of the elastic filament. Two or more of the regions are arranged substantially in parallel with the extending direction. In this case, the pitches of the adjacent elastic filaments are different and / or the diameters of the elastic filaments are different between the regions having different elongation stresses. Thereby, the elongation stress can be made different between the regions. Even when two or more different resins are introduced into an arbitrary spinning nozzle to perform spinning at the time of producing the moisture-permeable stretch sheet, the elongation stress between the regions can be made different.

  In each of the above-described embodiments, the moisture-permeable stretchable sheet 10 can be partially embossed, or the elastic filament 13 can be partially cut or partially heat-sealed. These operations are performed for the purpose of forming a non-stretchable portion in the moisture-permeable stretchable sheet 10 or partially increasing the strength. Alternatively, it is performed for the purpose of bonding with other members or providing design.

  Further, regarding the elastic expression processing using the elastic expression processing device 22, the elastic expression processing direction is not limited to the flow direction of the sheets 11 and 12, but may be, for example, an oblique direction. Furthermore, it is possible to combine two or more kinds of elastic expression treatment methods, increase the draw ratio stepwise, or partially perform the elastic expression treatment. The elastic development processing direction may be not only one direction but also two orthogonal directions.

  Moreover, in the manufacturing method of the said embodiment, although the elastic expression processing apparatus provided with a pair of tooth space roll 20 and 21 was used for the elastic expression processing, it replaced with using the elastic expression processing apparatus provided with the tenter. Elasticity treatment processing may be performed.

  Furthermore, in the manufacturing method described above, as another method for joining the elastic filament 13 and the sheets 11 and 12, the elastic filament 13 can be directly extruded on one sheet without being melted and stretched directly. The draw ratio in this case is 1 time. Moreover, before joining the elastic filament 13 and the sheet | seats 11 and 12, an adhesive agent can be apply | coated to a sheet | seat or an elastic filament auxiliary, and an elastic filament can also be bonded together in the substantially unexpanded state after that. Furthermore, after applying the elastic filament 13 and the sheets 11 and 12 without applying an adhesive, the heat treatment (spraying hot air using an air-through method, steam jet, heat embossing) or mechanical entanglement (needle punch, span) Race). At this time, a fiber web can be used on one side or both sides instead of the nonwoven fabric.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples.

[Example 1]
A moisture-permeable stretchable sheet having the structure shown in FIGS. 1 and 2 was produced using the apparatus shown in FIG. As the first sheet 11, a moisture permeable film having a basis weight of 24 g / m ² was used. As the second sheet 12, an air-through nonwoven fabric having a basis weight of 20 g / m ² was used. The constituent fiber of this nonwoven fabric was a core-sheath type composite fiber (core: PET, sheath: PE) having a diameter of 19 μm, a maximum elongation of 180%, and a fiber length of 44 mm. As a raw material resin for the elastic filament 13, an elastomer made of SEPS resin (weight average molecular weight 50,000, MFR 60 g / 10 min (230 ° C., 2.16 kg, JIS K7210: 1999)) was used. The spinning conditions were a temperature of the spinning head 17 of 310 ° C., a diameter of the spinning nozzle 16 of 400 μm, and a pitch of the spinning nozzle 16 of 1.5 mm. The diameter of the elastic filament 13 was 120 μm. The apparent basis weight (filament weight in the sample / sampling sheet area) of the filament was 10 g / m ² and the draw ratio was 11 times. The draw ratio is defined by (nozzle hole diameter / fiber diameter before elastic expression treatment). The elastic expression processing was performed using an elastic expression processing device 22 provided with a pair of tooth gap rolls 20 and 21 in which teeth and roots were alternately formed in the axial length direction. The pitch between teeth and the bottom of each tooth was 2.0 mm (the pitch P between teeth in the meshed state was 1.5 mm). The pressing amount of the upper and lower tooth gap rolls was adjusted, and the composite 19 was elastically treated in the extending direction of the elastic filament 13 at a draw ratio of 2.3 times. As a result, a water-impermeable, moisture-permeable stretch sheet 10 having a basis weight of 57 g / m ² that stretches in the direction in which the elastic filament 13 extends was obtained. The obtained moisture-permeable stretch sheet 10 exhibited a striped pattern resulting from stretching during the elastic expression treatment.

[Evaluation]
About the moisture-permeable elastic sheet obtained in Example 1, 30% return strength / 30% strength, 30% return strength and moisture permeability were measured by the following methods. The results are shown in Table 1 below.

[30% return strength / 30% strength, 30% return strength]
A moisture-permeable stretch sheet was cut out in a size of 200 mm in the stretch direction and 50 mm in a direction perpendicular to the stretch direction, to obtain a test piece. Shimadzu Corporation: A test piece was mounted on an autograph AG-IS 1 kN at a distance between chucks: 150 mm. The test piece was stretched in the stretching direction at a speed of 300 mm / min. The load at the time of extending 30% was recorded, and the value was taken as 30% strength. Subsequently, the test piece was stretched to 70%, and then shrunk at the same speed in the return direction (shrink direction) to be stretched by 30% with respect to the length of the group. The load at that time was recorded, and the return strength was 30%.

[Moisture permeability]
The moisture permeability was measured according to JIS Z-0208 in an environment of a temperature of 30 ° C. ± 0.5 ° C. and a humidity of 90 ± 12% RH.

  As is clear from the results shown in Table 1, it can be seen that the moisture-permeable stretch sheets of the examples have good stretch properties and good moisture permeability.

FIG. 1 is a partially broken perspective view showing a first embodiment of a moisture-permeable stretch sheet of the present invention. FIG. 2 is a photograph of the moisture-permeable stretch sheet according to one embodiment of the present invention taken from the first non-stretch moisture-permeable film side in its natural state (relaxed state). FIG. 3 is an SEM image showing an example of an inelastic fiber in which the diameter (cross-sectional area) of the fiber is changed in a substantially step shape. FIG. 4 is a schematic view showing an apparatus suitably used for manufacturing the moisture-permeable stretchable sheet shown in FIG. FIG. 5 is a schematic view showing a state in which the composite is subjected to an elastic expression treatment by the apparatus shown in FIG. FIG. 6 is a schematic diagram showing a state where the non-elastic fiber is subjected to an elastic expression process. FIG. 7 is a partially broken perspective view (corresponding to FIG. 1) showing a second embodiment of the moisture-permeable stretch sheet of the present invention. FIG. 8 is a partially broken perspective view (corresponding to FIG. 1) showing a third embodiment of the moisture-permeable stretch sheet of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Moisture-permeable elastic sheet 11 1st sheet 12 2nd sheet 13 Elastic filament 13A Elastic film 13B Elastic strip

Claims (7)

  A first non-stretchable moisture permeable film in which a plurality of elastic filaments or elastic strips arranged so as to extend in one direction without crossing each other are stretchable over their entire length in a substantially non-stretched state; A moisture-permeable stretch sheet joined between a stretchable non-stretch sheet.   The moisture-permeable stretch sheet according to claim 1, wherein the stretchable non-stretch sheet is a stretchable non-stretchable nonwoven fabric or a stretchable second non-stretch moisture-permeable film.   The joining area of joining of the elastic filament, the first non-stretchable moisture-permeable film and the non-stretchable sheet is 1 to 30% with respect to the area of the moisture-permeable stretch sheet. Moisture permeable stretch sheet.   A moisture-permeable elastic film is joined between the stretchable first non-stretchable moisture-permeable film and the stretchable non-stretchable sheet over its entire length in a substantially non-stretched state. Moist elastic sheet.   The moisture-permeable stretch sheet according to claim 4, wherein the stretchable non-stretchable sheet is a stretchable non-stretchable nonwoven fabric or a stretchable non-stretchable second moisture-permeable film.   The moisture-permeable stretch sheet according to claim 4 or 5, wherein the elastic film has an elongation before joining of 50 to 500%.   Minute protrusions and recesses extending in the same direction are alternately formed on one surface and the other surface, and the recesses and protrusions on the other surface are located at the positions of the protrusions and recesses on one surface. The moisture-permeable stretch sheet according to any one of claims 1 to 6.