Patent Description:
In a disposable wearable article such as a disposable diaper, it is common to impart elasticity to appropriate places such as around legs and around a waist in order to improve fitting to a body surface. As a method of imparting elasticity, conventionally, a method of attaching an elongated elastic member such as a rubber thread in a state of being stretched in a longitudinal direction thereof has been widely adopted. However, when it is desired to impart elasticity at a certain width, a mode is adopted in which rubber threads are fixed while being arranged side by side at intervals in the width. In addition, there has been a proposed method in which an elastic sheet is attached in a state of being stretched in an elasticity imparting direction as a material excellent in fitting as a surface. (For example, see Patent Literature <NUM>).

A stretchable structure including this elastic sheet is obtained by stacking the elastic sheet between a first sheet layer and a second sheet layer, and bonding the first sheet layer and the second sheet layer through joint holes formed in the elastic sheet at a plurality of dot-shaped bonded portions arranged at intervals in a stretchable direction and a direction orthogonal thereto in a state in which the elastic sheet is stretched in the stretchable direction. The stretchable structure of the elastic sheet can be provided not only with a stretchable region in which elongation at elastic limit changes depending on the arrangement and area ratio of the bonded portions and the elongation at elastic limit changes, but also a non-stretchable region that hardly extends or contracts. In the stretchable region, in a natural length state, as the elastic sheet contracts between the bonded portions, an interval between the bonded portions becomes narrower, and pleats extending in a direction intersecting the stretchable direction are formed between the bonded portions in the first sheet layer and the second sheet layer. On the other hand, at the time of stretching, as the elastic sheet stretches between the bonded portions, the interval between the bonded portions and the pleats in the first sheet layer and the second sheet layer widen, and elastic stretching is allowed until a fully spread state of the first sheet layer and the second sheet layer.

The stretchable region by the elastic sheet is excellent in surface fitting is, is extremely flexible since there is no bonding between the first sheet layer and the second sheet layer, and the elastic sheet and bonding between the first sheet layer and the second sheet layer is extremely small, and has an advantage that the joint holes of the elastic sheet contribute to improvement of air permeability.

Meanwhile, a design is printed on the disposable wearable article, and examples of the design include a pattern for decoration (including picture and one-point character), function indication such as usage, use assistance, or size, or mark display such as a manufacturer, a product name, or a characteristic feature (for example, see <NUM>). In general, such a design printing section is printed on a material such as a nonwoven fabric included in an outer surface of the disposable wearable article, or a printed sheet is attached.

In addition, when such a general method is applied to the stretchable region, there is a problem that the design greatly collapses due to formation of the pleats in the design print material in the natural length state. Thus, to solve this problem, it has been proposed to provide a stretchable region by a stretchable structure including an elastic sheet, and print a design on a part of the elastic sheet located in the stretchable region (for example, see Patent Literature <NUM>). In this case, wrinkles or pleats are not formed by extension or contraction in the elastic sheet, and thus design collapse due to formation of the wrinkles or pleats on a prink target of the design does not occur. Furthermore, when the entire design uniformly extends or contracts, a shape of the design is uniformly deformed, and thus the overall balance of the design is not lost.

However, in the case of providing the non-stretchable region to the stretchable structure including the elastic sheet, when a uniform print is applied to a part corresponding to the stretchable region and a part corresponding to the non-stretchable region in the elastic sheet, the elastic sheet hardly contracts in the non-stretchable region, whereas the elastic sheet contracts to some extent in the stretchable region during wearing. Thus, a difference in design appearance becomes large between the stretchable region and the non-stretchable region. In particular, in the case of not being equal between the two regions, there is a problem that distortion of one of the regions is noticeable.

In order to improve the appearance of the design of the stretchable region in a worn state, it may be considered that the design is not printed only on the part of the elastic sheet located in the non-stretchable region. However, since it is generally difficult to stably position a non-printed part in the non-stretchable region during manufacturing, it is desired to uniformly print the design on the elastic sheet.

Therefore, a main object of the invention is to reduce the difference in design appearance between the stretchable region and the non-stretchable region in the worn state.

Disposable wearable articles solving the above problems are as follows.

A disposable wearable article having an elastic sheet stretchable structure in which an elastic sheet is stacked between a first sheet layer and a second sheet layer, and the first sheet layer and the second sheet layer are bonded through joint holes penetrating the elastic sheet or with the elastic sheet interposed therebetween at a plurality of bonded portions arranged at intervals,.

In this disposable wearable article, the first design and the second design are the same when the stretchable region and the non-stretchable region are at the elongation at elastic limit. This description merely means that uniform printing is applied to the part corresponding to the stretchable region and the part corresponding to the non-stretchable region in the elastic sheet. In addition, in this disposable wearable article, the stretchable direction dimension of the design elements of the first design when the stretch rate of the stretchable region is <NUM>% or more, that is, in a general worn state is <NUM>% or more the stretchable direction dimension of the design elements of the first design when the stretchable region is at the elongation at elastic limit. For this reason, there is little difference in appearance between the designs in the stretchable region and the non-stretchable region during wearing.

Note that "the same" with respect to the first design and the second design means that the design elements have the same dimensions, shapes, orientations, arrangements, etc. However, it is natural that the areas of the designs, the number of design elements that change depending on the area, or discontinuity, missing, etc. of the design elements may be different. In addition, "design elements" are elements included in a distinguishable part as a part different from other parts in the design, and is not particularly limited.

The disposable wearable article according to the first aspect, including:.

In general, the disposable wearable article does not frequently have a stretchable structure as a whole. This description is similarly applied to the case of adopting the elastic sheet stretchable structure. Therefore, in the disposable wearable article having the elastic sheet stretchable structure, to add a design to a wider range, as in this aspect, it is preferable to provide the third design to a non-stretchable sheet other than the elastic sheet extending from the non-stretchable region to a region not having the elastic sheet stretchable structure. In this case, similarly to a relationship between the first design and the second design, to enhance integrity of the design, the third design preferably includes design elements which are the same as the design elements of the first design when the stretchable region and the non-stretchable region are at the elongation at elastic limit. In this way, the difference in appearance between the first design and the third design decreases in the worn state.

Note that "the same" design elements with respect to the first design and the third design means that dimensions and shapes are the same, and colors and directions may be different.

In addition, a technical feature of the second aspect may not require the second design. Therefore, it is significant even when the second design is not provided. That is, the following disposable wearable article is possible.

The disposable wearable article according to the second aspect,.

In the case of providing the second design and the third design described above, in the non-stretchable region, there is concern that the design elements of the second design of the elastic sheet and the design elements of the third design of the non-stretchable sheet may overlap with each other, resulting in a cluttered appearance. Therefore, it is preferable that an interval of design elements of one design is sufficiently sparse with respect to a size of design elements of the other design, the design elements rarely overlap each other when compared to the other case, and clutter in appearance is suppressed as in this aspect.

In addition, a technical feature of the third aspect has significance in a case other than a case where "the third design includes design elements which are the same as the design elements of the first design when the stretch rate of the stretchable region is <NUM> to <NUM>%". That is, the following disposable wearable article is preferable.

The disposable wearable article according to any one of the first to third aspects,.

In the case of providing the stretchable region in the outer body of the underpants-type disposable wearable article, it is desirable to arrange the elastic sheet in a part of the outer body overlapping the absorber for manufacturing reasons. However, the part is a region not requiring extension and contraction, and is generally set to the non-stretchable region. Therefore, the above-mentioned first design and second design are particularly preferable for such an underpants-type disposable wearable article.

According to the invention, it is possible to reduce the difference in design appearance between the stretchable region and the non-stretchable region in the worn state.

Hereinafter, an example of an underpants-type disposable diaper will be referred to describe a disposable wearable article in detail with reference to the accompanying drawings. Note that a dotted pattern portion in the figures indicates an adhesive as bonding means that bonds respective components located on the front surface side and the back surface side thereof, and is formed by solid, bead, curtain, summit, or spiral coating of a hot melt adhesive, or pattern coating (transfer of the hot melt adhesive in a letterpress method), or application of an elastic member to an outer peripheral surface such as comb gun or sure wrap application instead of or together with the above methods in a fixed part of the elastic member. Examples of the hot melt adhesive include EVA-based, pressure sensitive adhesion rubber-based (elastomer-based), polyolefin-based, and polyester/polyamide-based adhesives, and can be used without any particular limitation. As bonding means that bonds respective components, it is possible to use means by material welding such as heat sealing or ultrasonic sealing.

<FIG> illustrate the underpants-type disposable diaper (hereinafter also simply referred to as a diaper) as an example of the disposable wearable article. Reference character ED indicates a stretchable direction ED of a stretchable region, which is the same direction as a width direction WD of the diaper in this example. Reference character XD indicates a direction orthogonal to the stretchable direction ED, which is the same direction as a front-back direction LD of the diaper in this example.

The underpants-type disposable diaper has an outer body <NUM> forming a front body F and a back body B, and an inner body <NUM> fixed to and integrated with an inner surface of the outer body <NUM>, and the inner body <NUM> is obtained by interposing an absorber <NUM> between a liquid pervious top sheet <NUM> and a liquid impervious sheet <NUM>. In manufacturing, after a back surface of the inner body <NUM> is bonded to an inner surface (upper surface) of the outer body <NUM> by bonding means such as a hot melt adhesive, the inner body <NUM> and the outer body <NUM> are folded at a center in a front-back direction LD (vertical direction), which is a boundary between the front body F and the back body B, and both side portions thereof are bonded by heat welding or a hot melt adhesive to form side seal portions <NUM>, thereby forming the underpants-type disposable diaper in which a waist opening and a pair of right and left leg openings are formed.

As illustrated in <FIG>, the inner body <NUM> has a structure in which the absorber <NUM> is interposed between the liquid pervious top sheet <NUM> and the liquid impervious sheet <NUM> made of polyethylene, etc., and absorbs and retains an excreted liquid passing through the top sheet <NUM>. A planar shape of the inner body <NUM> is not particularly limited, and is generally a substantially rectangular shape as illustrated in <FIG>.

As the top sheet <NUM> that covers the front surface side (skin side) of the absorber <NUM>, a perforated or non-perforated nonwoven fabric, a porous plastic sheet, etc. is preferably used. As a raw material fiber included in the nonwoven fiber, in addition to synthetic fibers such as polyolefin-based fiber such as polyethylene or polypropylene, polyester-based fiber, and polyamide-based fiber, it is possible to use regenerated fibers such as rayon and cupra, and natural fibers such as cotton, and it is possible to use a nonwoven fabric obtained by an appropriate processing method such as a spun lace method, a spun bond method, a thermal bond method, a melt blown method, or a needle punch method. Among these processing methods, the spun lace method is excellent in flexibility and drapability, and the thermal bond method is excellent in bulkiness and softness. When a plurality of through holes are formed in the top sheet <NUM>, urine and, etc. can be rapidly absorbed, and a dry touch property becomes excellent. The top sheet <NUM> extends up to the back surface side of the absorber <NUM> with side edge portions of the absorber <NUM> wrapped around.

As the liquid impervious sheet <NUM> covering the back surface side of the absorber <NUM> (non-skin contact side), a liquid impervious plastic sheet of polyethylene, polypropylene, etc. is used. However, in recent years, a sheet having moisture permeability is preferably used from a viewpoint of preventing stuffiness. This water blocking and moisture-permeable sheet is, for example, a microporous sheet obtained by melt kneading an inorganic filler in a polyolefin resin such as polyethylene or polypropylene to form a sheet, and then monoaxially or biaxially stretching the sheet.

As the absorber <NUM>, it is possible to use a known one, for example, an accumulates of pulp fibers, an assembly of filaments such as cellulose acetate, or one having a nonwoven fabric as a base and a super absorbent polymer mixed and fixed therein as necessary. The absorber <NUM> can be wrapped with a wrapping sheet <NUM> such as crepe paper having the liquid pervious property and liquid holding property to hold the shape and the polymer as necessary.

A shape of the absorber <NUM> can be a substantially hourglass shape having a narrowing part 13N narrower than both front and back sides in a crotch portion. Dimensions of the narrowing part 13N can be appropriately determined. However, a front-back direction dimension of the narrowing part 13N can be set to about <NUM> to <NUM>% of a maximum length of the diaper, and a width of a narrowest part thereof can be set to about <NUM> to <NUM>% of a maximum width of the absorber <NUM>. In the case of having such a narrowing part 13N, when the planar shape of the inner body <NUM> is substantially rectangular, a non-absorber side portion <NUM> not having the absorber <NUM> is formed in a part of the inner body <NUM> corresponding to the narrowing part 13N of the absorber <NUM>.

The liquid impervious sheet <NUM> is folded back to the back surface side together with the top sheet <NUM> on both sides of the absorber <NUM> in the width direction. As the liquid impervious sheet <NUM>, it is desirable to use an opaque sheet so that brown of excreta, urine, etc. does not appear. As the opaque sheet, a film obtained by internally adding a pigment or a filler such as calcium carbonate, titanium oxide, zinc oxide, white carbon, clay, talc or barium sulfate to plastic is preferably used.

Three-dimensional gathers <NUM> fit around legs are formed on both sides of the inner body <NUM>. As illustrated in <FIG> and <FIG>, each of the three-dimensional gathers <NUM> has fixed portion <NUM> fixed to a side portion of a back surface of the inner body <NUM>, a main unit section <NUM> extending from the fixed portion <NUM> to a side portion on a front surface of the inner body <NUM> through a side of the inner body <NUM>, a fallen portion <NUM> formed by fixing front and back end portions of the main unit section <NUM> to the side portion of the front surface of the inner body <NUM> (top sheet <NUM> in the illustrated embodiment) in a fallen state, and a free part <NUM> formed by not fixing between fallen portions <NUM>. Each of these portions is formed by a gather sheet <NUM> that is a duplicate sheet obtained by folding back a sheet of a nonwoven fabric, etc. The gather sheet <NUM> is attached over the entire part of the inner body <NUM> in the front-back direction, the fallen portion <NUM> is provided on the front side and the back side of the non-absorber side portion <NUM>, and the free part <NUM> extends on both front and back sides of the non-absorber side portion <NUM>. In addition, an elongated gather elastic member <NUM> is arranged at a tip portion of the free part between parts of the double gather sheet <NUM>. The gather elastic member <NUM> is for raising the free part <NUM> by elastic contraction force as illustrated in <FIG> in a product state.

In the embodiment illustrated in <FIG> and <FIG>, in a part other than the fallen portion <NUM>, the gather elastic member <NUM> is attached and fixed to the gather sheet <NUM> through a hot melt adhesive at a position of the gather elastic member <NUM>, and facing surfaces of the gather sheet <NUM> are not bonded. However, in the fallen portion <NUM>, there is no hot melt adhesive at the position of the gather elastic member <NUM>, and therefore the gather elastic member <NUM> and the gather sheet <NUM> are not bonded, and the facing surfaces of the gather sheet <NUM> are not bonded at a position having the gather elastic member <NUM>.

The three-dimensional gathers <NUM> illustrated in <FIG> and <FIG> correspond to a mode in which the main unit sections <NUM> are not folded back.

Examples of the gather elastic member <NUM> include a commonly used material such as polystyrene-based rubber, polyolefin-based rubber, polyurethane-based rubber, polyester-based rubber, polyurethane, polyethylene, polystyrene, styrene-butadiene copolymer, silicone, or polyester. Further, in order to make it difficult to see from the outside, it is preferable that the thickness is <NUM> dtex or less, the tension is <NUM> to <NUM>%, and the interval is <NUM> or less. Note that as the gather elastic member <NUM>, in addition to a thread-shaped member as in the illustrated embodiment, it is possible to use a tape-shaped member having a certain width.

As a row material fiber included in the gather sheet <NUM>, similarly to the top sheet <NUM>, in addition to synthetic fibers such as polyolefin-based fiber such as polyethylene or polypropylene, polyester-based fiber, and polyamide-based fiber, it is possible to use regenerated fibers such as rayon and cupra, and natural fibers such as cotton, and it is possible to use a nonwoven fabric obtained by an appropriate processing method such as a spun bond method, a thermal bond method, a melt blown method, or a needle punch method. In particular, in order to prevent stuffiness, it is preferable to use a nonwoven fabric having a low basis weight and excellent air permeability. Further, with regard to the gather sheet <NUM>, in order to prevent the permeation of urine, etc., prevent the rash, and enhance the texture (dry feeling), it is desirable to use a water-repellent nonwoven fabric coated with a silicone-based, paraffin metal-based, or alkylchromic chloride-based water repellent agent.

As illustrated in <FIG>, the back surface of the inner body <NUM> is bonded to the inner surface of the outer body <NUM> by a hot melt adhesive, etc. in an inner/outer fixing region 10B (diagonal line region). The inner/outer fixing region 10B can be appropriately determined and can be set to almost the entire part of the inner body <NUM> in the width direction WD, and it is preferable that both end portions in the width direction are not fixed to the outer body <NUM>.

The outer body <NUM> extends outward from side edges of the absorber <NUM>. Referring to the outer body <NUM>, side edges of the outer body <NUM> may be located on the center side of side edges of the inner body <NUM> in the width direction in the crotch portion as in the illustrated embodiment, or located on the outer side thereof in the width direction. In addition, the outer body <NUM> has a lower torso portion T which is a front-back direction range corresponding to the side seal portions <NUM> and an intermediate portion L which is a front-back direction range between the lower torso portion T of the front body F and the lower torso portion T of the back body B. A planar shape of the outer body <NUM> is formed by concave around-leg lines <NUM> so that both side edges of the intermediate portion L in the width direction form leg openings, respectively, and forms a shape similar to an hourglass as a whole. The outer body <NUM> may be separately formed in the front body F and the back body B, and both parts may be arranged to be separated in the front-back direction LD of the diaper in the crotch portion.

Further, except for a middle of the intermediate portion L in the front-back direction, the outer body <NUM> of the illustrated embodiment has an elastic sheet stretchable structure 20X in which an elastic sheet <NUM> such as an elastic film is interposed between the first sheet layer 20A and the second sheet layer 20B as illustrated in <FIG> and <FIG>, and the first sheet layer 20A and the second sheet layer 20B are bonded through joint holes <NUM> penetrating the elastic sheet <NUM> at a plurality of bonded portions <NUM> arranged at intervals as illustrated in <FIG>. In this case, the stretchable direction ED is the width direction WD of the diaper. The first sheet layer 20A and the second sheet layer 20B may be indirectly bonded via the elastic sheet <NUM> instead of through the joint holes <NUM> of the elastic sheet <NUM>.

The mode illustrated in <FIG> and <FIG> is a mode in which the elastic sheet stretchable structure 20X is extended to waist end portions <NUM>. However, when the elastic sheet stretchable structure 20X is used in the waist end portions <NUM>, tightening of the waist end portions <NUM> is insufficient. As necessary, as illustrated in <FIG> and <FIG>, instead of providing the elastic sheet stretchable structure 20X in the waist end portions <NUM>, it is possible to provide a stretchable structure by conventional elongated waist portion elastic members <NUM>. The waist portion elastic members <NUM> are elongated elastic members such as a plurality of rubber threads arranged at intervals in the front-back direction LD, and gives a stretching force so as to tighten around a waist of a body. The waist portion elastic members <NUM> may not be arranged closely substantially in a bundle, and three or more, preferably five or more waist portion elastic members <NUM> are arranged at intervals of about <NUM> to <NUM> in the front-back direction to form a predetermined stretchable zone. A stretch rate of the waist portion elastic members <NUM> during fixing can be appropriately determined. However, in the case of using for normal adults, the stretch rate can be set to about <NUM> to <NUM>%. The waist portion elastic members <NUM> are made of rubber threads in the illustrated example. However, for example, it is possible to use other elongated elastic members such as flat rubbers. Although not illustrated, it is possible to provide the elastic sheet <NUM> in the waist end portions <NUM>, and provide the elongated waist portion elastic members <NUM> at positions overlapping the elastic sheet <NUM>, thereby forming a stretchable structure by both the elastic members. In addition, in the illustrated embodiment, the elongated elastic members extending along the leg openings are not provided at edge parts of the leg openings in the outer body <NUM>. However, it is possible to provide elongated elastic members at positions of the edge parts overlapping the elastic sheet <NUM> or in place of the elastic sheet <NUM> at the edge parts.

As another mode, although not illustrated, it is possible to adopt a mode in which the elastic sheet stretchable structure 20X is not provided to the intermediate portion L between the lower torso portion T of the front body F and the lower torso portion T of the back body B, or an appropriate modification in which the elastic sheet stretchable structure 20X is provided continuously in the front-back direction LD from the inside of the lower torso portion T of the front body F to the inside of the lower torso portion T of the back body B through the intermediate portion L, or the elastic sheet stretchable structure 20X is provided only to one of the front body F and the back body B.

As illustrated in <FIG> and <FIG>, cover sheets <NUM> and <NUM> are provided to reinforce the outer body <NUM> or cover front and back end portions of the inner body <NUM> attached to the inner surface of the outer body <NUM>. The illustrated embodiment will be more specifically described. The cover sheet <NUM> on the front side extends over the entire part in the width direction WD from an inner surface of a folded part 20C on the waist side in the inner surface of the front body F to a position overlapping the front end portion of the inner body <NUM>, and the cover sheet <NUM> on the back side extends over the entire part in the width direction WD from the inner surface of the folded part 20C on the waist side in the inner surface of the back body B to a position overlapping the back end portion of the inner body <NUM>. Bonding between the cover sheets <NUM> and <NUM> and the inner surface of the outer body <NUM>, that is, the inner surface of the first sheet layer 20A in the illustrated example can be performed by a hot melt adhesive or by material welding. When a slight non-bonded portion is provided over the entire part in the width direction WD (or may be provided only at a center portion) at a crotch side edge portion of each of the cover sheets <NUM> and <NUM>, this portion can be slightly lifted from the top sheet <NUM> to function as a leak prevention wall.

When the cover sheets <NUM> and <NUM> are separately attached as in the illustrated embodiment, there is an advantage that a degree of freedom in selecting a material is increased. However, there is a demerit that the number of materials and the manufacturing process are increased. For this reason, the folded part 20C obtained by folding back the outer body <NUM> on the inner surface of the diaper can be extended to the part overlapping the inner body <NUM> to form a part equivalent to the above-described cover sheets <NUM> and <NUM> (not illustrated).

A region of the outer body <NUM> having the elastic sheet stretchable structure 20X has a stretchable region that can be extended and contracted in the width direction WD. In a stretchable region <NUM>, the elastic sheet <NUM> has a part <NUM> (see <FIG>) that is linearly continuous along the width direction WD, contracts in the width direction WD by a contraction force of the elastic sheet <NUM>, and is stretchable in the width direction WD. More specifically, in a state where the elastic sheet <NUM> is extended in the width direction WD, the first sheet layer 20A and the second sheet layer 20B are bonded through the joint holes <NUM> of the elastic sheet <NUM> at intervals in the width direction WD and the front-back direction LD orthogonal thereto (direction LD orthogonal to the stretchable direction), and the plurality of bonded portions <NUM> is formed, thereby forming the elastic sheet stretchable structure 20X. Further, in the stretchable region <NUM>, such elasticity can be imparted by arranging the joint holes <NUM> so that the elastic sheet <NUM> has the part <NUM> (see <FIG>) that is linearly continuous along the width direction WD.

The stretchable region <NUM> may have a part (separation interval d described later) in which the elastic sheet <NUM> is linearly continuous along the width direction WD as in an example illustrated in <FIG> described later or may not have the part as in an example illustrated in <FIG>.

In the natural length state, as illustrated in <FIG> and <FIG>, the stretchable region <NUM> bulges in a direction in which the first sheet layer 20A and the second sheet layer 20B between the bonded portions <NUM> are separated from each other, and pleats 25F extending in the front-back direction LD are formed. Even in a worn state of extending in the width direction WD to some extent, the pleats 25F are left even though the pleats 25F are stretched. In addition, as in the illustrated example, when the first sheet layer 20A and the second sheet layer 20B are not bonded to the elastic sheet <NUM> except at least between the first sheet layer 20A and the second sheet layer 20B in the bonded portions <NUM>, as can be seen from <FIG> presuming the worn state and <FIG> presuming a spread state of the first sheet layer 20A and the second sheet layer 20B, in these states, a gap is formed between the joint holes <NUM> in the elastic sheet <NUM> and the bonded portions <NUM>, and air permeability is imparted by this gap even when the material of the elastic sheet <NUM> is a non-perforated film or sheet. In addition, in the natural length state, the joint holes <NUM> are narrowed by further contraction of the elastic sheet <NUM>, and almost no gap is formed between the joint holes <NUM> and the bonded portions <NUM>.

It is desirable that elongation at elastic limit of the stretchable region <NUM> in the width direction WD is set to <NUM>% or more (preferably <NUM> to <NUM>%). The elongation at elastic limit of the stretchable region <NUM> decreases due to a factor that inhibits contraction in the width direction WD based on a stretch rate of the elastic sheet <NUM> at the time of manufacturing. In a normal case, a length L of the bonded portions <NUM> has a correlation with an area ratio of the bonded portions <NUM>, and thus the elongation at elastic limit of the stretchable region <NUM> can be adjusted by the area ratio of the bonded portions <NUM>.

Where the elastic sheet <NUM> has the part (separation interval d described later) which is linearly continuous along the width direction WD as in the example illustrated in <FIG> described later, the extension stress of the stretchable region <NUM> can be adjusted mainly by a sum of orthogonal direction dimensions (equal to the separation interval d of the joint holes <NUM>) of the part in which the elastic sheet <NUM> is linearly continuous along the width direction WD. On the other hand, where the elastic sheet <NUM> has not the part which is linearly continuous along the width direction WD as in the example illustrated in <FIG>, the extension stress can be adjusted by an angle γ described later. In a normal case, it is preferable that the angle γ is set to a range of more than <NUM> degree and <NUM> degrees or less, particularly to a range of <NUM> to <NUM> degrees.

The area ratio of the bonded portions <NUM> and the area of each of the bonded portions <NUM> in the stretchable region <NUM> can be appropriately determined. However, in the normal case, the area ratio and the area are preferably within the following ranges.

In this way, since the elongation at elastic limit and the extension stress of the stretchable region <NUM> can be adjusted by the area of the bonded portions <NUM>, as illustrated in <FIG>, a plurality of regions having different area ratios of the bonded portions <NUM> can be provided in the stretchable region <NUM> to change fitting depending on the site. In an example illustrated in <FIG>, edge portion stretchable regions <NUM> of the leg openings are provided, and the edge portion stretchable regions <NUM> are set to flexibly extending and contracting regions in which the area ratio of the bonded portions <NUM> is higher than that of other regions, and thus the extension stress is weak.

A shape of each of the bonded portions <NUM> and the joint holes <NUM> in the natural length state can be appropriately determined, and can be set to an arbitrary shape such as a perfect circle, an ellipse (see <FIG>), a polygon such as a triangle, a rectangle (see <FIG>, etc.), or a rhombus (see <FIG>), a convex lens shape (see <FIG>), a concave lens shape (see <FIG>, a star shape, or a cloud shape. Dimensions of each of the bonded portions <NUM> are not particularly limited. However, a maximum length 40y (almost equal to the dimension 31y of the joint holes <NUM> in the orthogonal direction) is preferably <NUM> to <NUM>, particularly <NUM> to <NUM>, and a maximum width 40x is preferably <NUM> to <NUM>, particularly <NUM> to <NUM> in the case of a shape which is long in the direction XD orthogonal to the stretchable direction.

The joint holes <NUM> mainly relate to the shape of the bonded portions <NUM> (<NUM>, <NUM>, and <NUM>) and a manufacturing stage or a degree of extension and contraction.

Hereinafter, arrangement examples of the bonded portions suitable for the stretchable region will be described in order.

<FIG> is illustrated as a representative example in Patent Literature <NUM>. That is, a group of the bonded portions <NUM> is in staggered arrangement, the bonded portions <NUM> have a line-symmetrical shape (right-left symmetry in <FIG>) with respect to a center line passing through a center in the stretchable direction, which is elongated in the direction orthogonal to the stretchable direction, the width 40x of the bonded portions <NUM> in the stretchable direction is preferably set to <NUM> to <NUM>, an interval d1 of the bonded portions <NUM> arranged in the stretchable direction is set to <NUM> to <NUM>, more preferably <NUM> to <NUM>, and an interval d2 of the bonded portions <NUM> arranged in the direction orthogonal to the stretchable direction is set to <NUM> to <NUM>, more preferably <NUM> to <NUM>.

In this way, the bonded portions <NUM> having a remarkably narrow width 40x in the stretchable direction are arranged in a staggered shape at the separation interval d1 which is wide to some extent in the stretchable direction, the contraction force of the elastic sheet <NUM> directly acts on each of the bonded portions <NUM>, and arrangement/interval of the respective bonded portions <NUM> are firmly maintained at positions of the joint holes <NUM> of the elastic sheet <NUM>. As a result, flexibility is less likely to deteriorate. In addition, pleats 25f extend almost straight along the direction orthogonal to the stretchable direction, and the bonded portions <NUM> are hidden between the pleats 25f and the pleats 25f and become inconspicuous. Therefore, the elastic sheet stretchable structure 20X has an appearance closer to that of cloth while suppressing deterioration in flexibility.

On the other hand, even though arrangement of the bonded portions <NUM> is staggered arrangement, when the shape of each of the bonded portions <NUM> is a circular shape, the bonded portions <NUM> are clearly visible between the pleats 25f and the pleats 25f which are wrinkles, and the pleats 25f greatly wrap around the bonded portions <NUM> and extend in the direction orthogonal to the stretchable direction. Thus, the wavy line-shaped pleats 25f are formed as a whole, and cloth-like appearance is less likely to be obtained.

From this point of view, it is desirable that the shape of each of the bonded portions <NUM> is elongated in the direction orthogonal to the stretchable direction. However, when the maximum length of the bonded portions <NUM> in the direction orthogonal to the stretchable direction is excessively short or excessively long, there is concern that linearity of the pleats 25f may decrease, or flexibility may decrease. Therefore, these dimensions can be appropriately determined. However, it is preferable that the length 40y of the bonded portions <NUM> in the direction orthogonal to the stretchable direction is <NUM> to <NUM>, and particularly <NUM> to <NUM>.

Meanwhile, in Patent Literature <NUM>, in both examples of <FIG><FIG>, arrangement of bonded portions of an elastic film (illustrated as a rather vertically long rectangle) is similarly staggered arrangement, and in the example of <FIG>, small circular sub-bonded portions are arranged between rectangular main bonded portions. The example of <FIG> is based on the idea of staggered arrangement.

Further, arrangement and dimensions of the respective bonded portions are preferably within dimensional ranges (unit is mm) illustrated in <FIG> mainly in terms of appearance, touch, and air permeability.

In arrangement example <NUM> described above, the separation interval between the bonded portions of the elastic sheet <NUM> in the direction orthogonal to the stretchable direction, which is reference character C in <FIG>, is set to be a large value of <NUM> or more, and thus stretching stress in the stretchable direction is high. For example, in the case of applying to the underpants type disposable diaper, there are not a few wearers who feel that the wearers are excessively tightened (in the width direction).

Here, in Patent Literature <NUM>, it is preferable that a length B of the bonded portions illustrated in <FIG> is <NUM> to <NUM>, and a separation interval H is <NUM> to <NUM>.

On the other hand, as illustrated in <FIG>, when the separation interval d between the bonded portions of the elastic sheet <NUM> in the orthogonal direction XD orthogonal to the stretchable direction ED is set to be small, the stretching stress in the stretchable direction can be reduced. Therefore, in the case of applying to the underpants-type disposable diaper, the disposable diaper can be gently fit to the wearer with a weak tightening force.

A reason therefor is considered as follows. While the bonded portions are open in the width direction and become the joint holes <NUM> as illustrated in <FIG> merely by applying a small stretching force in the width direction (stretchable direction of the elastic sheet <NUM>) from the outside, the bonded portions are not present in a separation interval region orthogonal to the stretchable direction between the bonded portions even when stretched in the width direction. Thus, the extension stress of the elastic sheet <NUM> becomes a contraction force without change to tighten the wearer.

The mode illustrated in <FIG> has an advantage that the diaper can be gently fit to the wearer, and air permeability is excellent since an area ratio of the bonded portions and an area ratio of the joint holes in a use state of being stretched in the width direction increase.

Arrangement example <NUM> described above has an advantage that the diaper can be gently fit to the wearer. However, it may be desirable to apply a weaker contraction force.

In addition, a product provider generally sets a wearer having an intermediate body type within a certain body type (size around the waist) group range and determines the contraction force of the diaper for the wearer.

There are large individual differences in the size around the waist, and there is a desire for a product in which the contraction force of the diaper with respect to the wearer does not change much between a person having a large waist and a person having a thin waist as much as possible.

<FIG> illustrates one possible solution to this problem. In more detail, in an example illustrated in <FIG>, in the stretchable region, the bonded portions <NUM> are formed to be spaced apart in the stretchable direction ED and the orthogonal direction XD orthogonal thereto,.

A reason why this example does not give an excessive contraction force to the wearer is presumed to be due to the following phenomenon even though the reason may not be clear.

It is considered that stretching in the stretchable direction may not occur when the bonded portion group is in the relationship of intersecting the stretchable direction line at each position in the orthogonal direction XD as in <FIG>, or is in a relationship of not intersecting the stretchable direction line at the separation interval d of <NUM> or less in the orthogonal direction XD of the stretchable direction line as in <FIG>.

However, a force in the stretchable direction in the case of spreading in the stretchable direction ED during wearing is propagated while making a detour as in <FIG> (a propagation path is indicated by reference character S). The propagation path S is illustrated since the elastic sheet <NUM> extends and contracts in the orthogonal direction in addition to the width direction. As a result, extension in the stretchable direction ED occurs while forming the joint holes <NUM> and <NUM> on both sides of the bonded portion <NUM> in the width direction.

In general, when the elastic sheet <NUM> is stretched during manufacturing, and then a stretching force is released, the elastic sheet <NUM> does not return to an original length and returns to a length obtained by subtracting strain. For example, when an elastic sheet having a natural length of <NUM> is stretched <NUM> times to <NUM> and a stretching force is released to <NUM>, there is a strain of <NUM>, and a strain ratio ε% is (<NUM> - <NUM>) × <NUM>/<NUM> = <NUM>%.

Based on this fact, when further studied, in the spread state of the diaper in the width direction, stretching in the stretchable direction occurs while forming the joint holes <NUM> and <NUM> on both sides of the bonded portion <NUM> in the width direction. That is, the elastic sheet is deformed on both sides of the bonded portion <NUM> in the width direction by the openings of the joint holes <NUM> and <NUM>. It will be understood that the part that has once deformed has a smaller contraction force.

In this way, when a spreading force of the diaper is released, contraction in the width direction occurs while shorting an opening width (opening length) of the joint holes <NUM> and <NUM> by the contraction force of the elastic sheet. In this case, when the separation interval d is large, the elastic sheet is not deformed in a separation interval d region, and thus the amount (length) of contraction in the width direction is large. For example, in the case of a thin person, contraction occurs until the joint holes <NUM> and <NUM> are closed. As a result, there is concern that air permeability from the openings of the joint holes <NUM> and <NUM> may be insufficiently ensured.

On the other hand, when the separation interval d is small or zero, the elastic sheet <NUM> is deformed by the openings of the joint holes <NUM> and <NUM> (in a sense, the elastic sheet is damaged) in the all part or almost all part in the orthogonal direction. As a result, when the stretching force in the width direction is released, the opening width (opening length) of the joint holes <NUM> and <NUM> that have been once opened is short and a ratio thereof is small. Therefore, ensuring of the air permeability from the openings of the joint holes <NUM> and <NUM> is not excessively reduced.

Moreover, the contraction force in the width direction is smaller than that in a case where the separation interval d is large, and thus the wearer is not excessively pressed.

Note that, for example, to cause extension and contraction in the width direction in the propagation path S, as illustrated in <FIG>, at a predetermined separation interval H in the orthogonal direction XD in a orthogonal direction diagonal line group of the diagonal lines q and q intersecting the stretchable direction line within the range of the angle γ of <NUM> degrees or less, the group of bonded portions <NUM>, <NUM>. needs to be in a relationship not intersecting the diagonal lines.

Here, for example, as illustrated in <FIG>, the angle γ of <NUM> degrees or less with respect to the stretchable direction line is defined as an opening angle between the stretchable direction line and the diagonal line q even in the case of a diagonal line from the upper left to the lower right.

The separation interval H along the orthogonal direction XD is <NUM> to <NUM>, more desirably <NUM> to <NUM>, and particularly desirably <NUM> to <NUM>.

The opening angle γ between the stretchable direction line and the diagonal line is more preferably <NUM> degrees or less, and particularly desirably <NUM> degrees or less.

The bonded portions <NUM> are formed to have a stretchable direction width of <NUM> to <NUM>, preferably <NUM> to <NUM>, and particularly preferably <NUM> to <NUM>.

The bonded portions <NUM> are formed to have a length L based on the orthogonal direction XD in a range of <NUM> to <NUM>, preferably <NUM> to <NUM>, and particularly preferably <NUM> to <NUM>.

In addition, a row of first bonded portions <NUM>, <NUM>. is formed to have a forming pitch S0 based on the stretchable direction ED (WD) in a range of <NUM> to <NUM>, preferably <NUM> to <NUM>, and particularly preferably <NUM> to <NUM>.

Hereinafter, various modifications based on the above-mentioned arrangement example <NUM> will be described in order.

In a usage form of a product having a form illustrated in <FIG>, the pleats 25F along the orthogonal direction XD are formed in a separation region between a row of bonded portions <NUM>, <NUM>. along the orthogonal direction XD and a row of adjacent bonded portions <NUM>, <NUM>. spaced apart therefrom in the stretchable direction ED. As illustrated in <FIG>, the pleats 25F simply have a uniform mountain shape. That is, the shape is different from that in the cross section shown in Patent Literature <NUM> and illustrated here in <FIG>.

The example illustrated in <FIG> has the elastic sheet stretchable structure in which the elastic sheet is interposed between the first sheet layer having air permeability and the second sheet layer having air permeability, and the first sheet layer and the second sheet layer are bonded through the joint holes penetrating the elastic sheet or with the elastic sheet interposed therebetween at a plurality of bonded portions arranged at intervals.

In addition, the stretchable region exhibiting the elastic sheet stretchable structure can be extended and contracted in the stretchable direction by the contraction force of the elastic sheet.

The bonded portions have second bonded portions <NUM>, <NUM>. in addition to the first bonded portions <NUM>, <NUM>.

The first bonded portions <NUM>, <NUM>. are arranged at intervals along the orthogonal direction XD, and a first bonded portion row is formed.

As will be described later with reference to <FIG>, for example, the row of the first bonded portions <NUM>, <NUM>. does not extend along the orthogonal direction XD and is inclined in a range in which an angle θ intersecting the stretchable direction ED is <NUM> degrees to <NUM> degrees (therefore <NUM> degrees is not included), and is more desirably inclined in a range of <NUM> degrees to <NUM> degrees (<NUM> degrees is not included).

In the example illustrated in <FIG>, the angle θ at which inclination does not occur and intersection occurs is <NUM> degrees.

The first bonded portions <NUM> are formed to have a length L based on the orthogonal direction XD in a rage of <NUM> to <NUM>, preferably <NUM> to <NUM>, and particularly preferably <NUM> to <NUM>.

Further, as a distance based on the orthogonal direction XD, which is determined by a mutual relationship between the adjacent first bonded portions <NUM> and <NUM> in the row of the first bonded portions <NUM>, <NUM>. , a percentage R of a ratio of (separation distance d between adjacent first bonded portions)/(distance P from a point of the bonded portions to a point corresponding to an adjacent first bonded portion) is desirably set to <NUM> to <NUM>%, preferably <NUM> to <NUM>%, and particularly <NUM> to <NUM>%.

When this percentage is excessively high, in the case of being applied to a product, the stretching stress in the width direction (stretchable direction) is high, and it tends to be difficult to obtain suitable fitting as a wearable article.

In addition, when the percentage is excessively low, it is impossible to exclude the possibility that the first bonded portions <NUM> and <NUM> adjacent to each other in the orthogonal direction XD may become mutually continuous in a manufacturing process. More fundamentally, an anvil and a heating horn that form the bonded portions may have an excessive facility load, which may hinder stable operation.

It is desirable that a bonded portion having the length L of the first bonded portions <NUM> or a larger length is not formed in the row of the second bonded portions <NUM> and <NUM>.

In this example, the following advantages or characteristics are typically shown.

Moreover, since an opening ratio becomes high, the air permeability becomes high.

As illustrated in <FIG>, the group of the second bonded portions <NUM>, <NUM>. can be arranged between the first bonded portions <NUM> and <NUM> in the orthogonal direction XD. In this case, even when the length L of the first bonded portion <NUM> is short, the stretching stress can be reduced since the second bonded portions <NUM> are positioned.

As illustrated in <FIG>, the second bonded portions <NUM> may not be adjacent to the first bonded portions <NUM> on a one-to-one basis. For example, it is possible to adopt a mode in which one second bonded portion <NUM> is arranged to be adjacent to two first bonded portions <NUM> and <NUM>.

As illustrated in <FIG>, a row of third bonded portions <NUM>, <NUM>. having a long separation interval in the orthogonal direction XD can be formed between the row of the first bonded portions <NUM>, <NUM>. and the row of the second bonded portions <NUM>, <NUM>. By forming the third bonded portion <NUM>, it is possible to form a large pleat bf obtained by dividing the inter-row pleat R illustrated in a first embodiment in the orthogonal direction XD. A small pleat sf can be formed between the third bonded portion <NUM> and the row of the first bonded portions <NUM>, <NUM>. A group of pleats formed by dividing the inter-row pleat R lowers flexural rigidity of the stretchable member (easy to bend) and has excellent followability to movement of the body.

As illustrated in <FIG>, by obliquely arranging positions of the third bonded portions <NUM> together with the second bonded portions <NUM>, a group of large pleats bf in oblique arrangement can be formed, and a design property is enhanced.

As illustrated in <FIG>, a fourth bonded portion <NUM> can be arranged to be inserted into the row of the first bonded portions <NUM>, <NUM>. In this case, a group of the fourth bonded portions <NUM>, <NUM>. extends along the stretchable direction ED, and can be obliquely arranged as illustrated in the figure. In this case, the area of the fourth bonded portion <NUM> is preferably <NUM>% or more and <NUM>% or less of the area of the first bonded portion <NUM>.

As illustrated in <FIG>, the first bonded portion <NUM> may be inclined. The second bonded portion <NUM> may be inclined. Since the bonded portion length is based on the orthogonal direction XD, as illustrated in <FIG>, the length L of the first bonded portion <NUM> is a bonded portion length corresponding to a length in the orthogonal direction XD from a center of one side to a center portion of the other side. As for the separation interval, a distance in the orthogonal direction XD between a center of a side and a center of an opposite side is a separation distance d.

<FIG> illustrates an example in which both the first bonded portions <NUM> and the second bonded portions <NUM> are inclined, and each of the row of the first bonded portions <NUM> and the row of the second bonded portions <NUM> does not extend along the orthogonal direction XD and is inclined in a range in which the angle θ intersecting the stretchable direction ED is <NUM> degrees to <NUM> degrees, desirably <NUM> degrees to <NUM> degrees. The intersecting angle θ is particularly preferably <NUM> degrees to <NUM> degrees. However, <NUM> degrees is naturally not included in these angular ranges showing inclination.

An advantage by this bonded portion row which does not extend in the orthogonal direction XD and is inclined to intersect with the stretchable direction ED becomes clear by comparing with an eighth embodiment illustrated in <FIG>. That is, in the example illustrated in <FIG>, a reason for having the advantage is that, for example, the separation interval between the first bonded portions <NUM> and <NUM> on the orthogonal direction XD line is considerably larger than that in the eighth embodiment illustrated in <FIG>.

That is, for example, bonding of the first sheet layer 20A and the second sheet layer 20B at the bonded portions <NUM> is desirably performed by bonding means by material welding such as heat sealing or ultrasonic sealing.

In the case of continuous production, seal melting by ultrasonic waves is performed between the anvil roll and the ultrasonic horn. However, in order to prevent energy loss, it is important that the ultrasonic horn is in close contact with the sheet throughout entire part of the anvil roll in an axial direction. For this reason, it is necessary to output a large ultrasonic wave in the case of forming a pattern having a large proportion of anvil roll convexes as the row of the bonded portions <NUM>, <NUM>. of <FIG> along a generatrix that makes line contact. To this end, when an excessive close force is applied along the generatrix that makes line contact, the load on the facility side is large.

On the other hand, in the case of this example (generally in the case of the inclined arrangement), the proportion of the bonded portions located on the line in the orthogonal direction XD is small, and the stable linear pressure is obtained. Thus, the facility load becomes small, and stable operation can be performed. In addition, in this example, the first bonded portions <NUM> (and the second bonded portions <NUM>) are inclined, and thus there is an advantage that the pleats excellent in the design property can be formed.

In the region of the outer body <NUM> having the elastic sheet stretchable structure 20X, as illustrated in <FIG>, a non-stretchable region <NUM> can be provided in addition to the stretchable region <NUM>. The non-stretchable region <NUM> means that the elongation at elastic limit in the stretchable direction is <NUM>% or less. The elongation at elastic limit of the non-stretchable region <NUM> is preferably <NUM>% or less, and more preferably <NUM>%. Arrangement of the stretchable region <NUM> and the non-stretchable region <NUM> can be appropriately determined. In the case of the outer body <NUM> of the underpants-type disposable diaper as in the illustrated example, a part overlapping the absorber <NUM> is a region that does not require extension and contraction. Thus, as in the illustrated example, it is preferable that a part or all of the part overlapping the absorber <NUM> (desirably including substantially the entire inner/outer fixing region 10B) is set to the non-stretchable region <NUM>. Naturally, the non-stretchable region <NUM> may be provided from the region overlapping the absorber <NUM> to the region not overlapping the absorber <NUM> positioned in the width direction WD or the front-back direction LD thereof, or the non-stretchable region <NUM> may be provided only in the region not overlapping the absorber <NUM>.

A shape and arrangement of the individual bonded portions <NUM> in the non-stretchable region <NUM>, and a shape and arrangement of the joint holes <NUM> in the elastic sheet <NUM> can be appropriately determined.

In addition, the area ratio of the bonded portions <NUM> and the area of the individual bonded portions <NUM> in the non-stretchable region can be appropriately determined. In a normal case, the following ranges are preferable since the area of each of the bonded portions <NUM> is small and the area ratio of the bonded portions <NUM> is low, so that the non-stretchable region <NUM> does not become hard.

The non-stretchable region <NUM> can be formed by arranging the bonded portions <NUM> densely so that the pleats are not formed by the first sheet layer and the second sheet layer contracting due to the contraction force of the elastic sheet <NUM>. Specific examples of the method of forming the non-stretchable region <NUM> include those shown in <CIT>, <CIT>, <CIT>, and <CIT>.

In particular, the non-stretchable region <NUM> is preferably a region not having a linearly continuous part along the width direction WD due to the presence of the joint holes <NUM> even though the elastic sheet <NUM> is continuous in the width direction WD. In this case, even when in a state where the elastic sheet <NUM> is extended in the width direction WD, the first sheet layer 20A and the second sheet layer 20B are bonded through the joint holes <NUM> of the elastic sheet <NUM> at intervals in the width direction WD and the front-back direction LD orthogonal thereto, and the plurality of bonded portions <NUM> is formed, thereby forming the entire elastic sheet stretchable structure 20X including both the stretchable region <NUM> and the non-stretchable region <NUM>, the elastic sheet <NUM> is not linearly continuous along the width direction WD in the non-stretchable region <NUM>. Thus, the contraction force of the elastic sheet <NUM> hardly acts on the first sheet layer 20A and the second sheet layer 20B, the elasticity is lost, and the elongation at elastic limit is close to <NUM>%.

In such a non-stretchable region <NUM>, the first sheet layer 20A and the second sheet layer 20B are bonded at a plurality of bonded portions <NUM> arranged at intervals, and the bonded portions <NUM> are not continuous. Thus, a decrease in flexibility is prevented.

In a case where bonding of the first sheet layer 20A and the second sheet layer 20B in the bonded portions <NUM> is performed through the joint holes <NUM> formed in the elastic sheet <NUM>, it is desirable that the first sheet layer 20A and the second sheet layer 20B are not bonded to the elastic sheet <NUM> except at least between the first sheet layer 20A and the second sheet layer 20B in the bonded portions <NUM>.

Bonding means for bonding the first sheet layer 20A and the second sheet layer 20B at the bonded portions <NUM> is not particularly limited. For example, bonding of the first sheet layer 20A and the second sheet layer 20B at the bonded portions <NUM> may be performed by a hot melt adhesive, or by bonding means by material welding such as heat sealing or ultrasonic sealing.

In a case where the first sheet layer 20A and the second sheet layer 20B are bonded through the joint holes <NUM> of the elastic sheet <NUM> in the bonded portions <NUM>, as a structure in which the bonded portions <NUM> are formed by material welding, it is possible to adopt any one of a first welded structure in which the first sheet layer 20A and the second sheet layer 20B are bonded only by a melted and solidified material <NUM> in a most part or a part of at least one of the first sheet layer 20A and the second sheet layer 20B in the bonded portions <NUM> (see <FIG>), a second welded structure in which the first sheet layer 20A and the second sheet layer 20B are bonded only by a melted and solidified material <NUM> in all, a most part, or a part of the elastic sheet <NUM> in the bonded portions <NUM> (see <FIG>), and a third welded structure in which both of these welded structures are combined (see <FIG>). However, the second and third welded structures are preferable.

A particularly preferable structure is a structure in which the first sheet layer 20A and the second sheet layer 20B are bonded by the melted and solidified material <NUM> in a part of the first sheet layer 20A and the second sheet layer 20B and the melted and solidified material <NUM> in all or a most part of the elastic sheet <NUM> in the bonded portions <NUM>. Note that in the third welded structure illustrated in <FIG>, the melted and solidified material <NUM> of the elastic sheet <NUM> shown in white is seen between melted and solidified materials <NUM> of the fibers of the first sheet layer 20A or the second sheet layer 20B shown in black. On the other hand, in the first welded structure illustrated in <FIG>, the melted and solidified material of the elastic sheet <NUM> is not seen between melted and solidified materials <NUM> of the fibers of the first sheet layer 20A or the second sheet layer 20B.

In the case of bonding the first sheet layer 20A and the second sheet layer 20B using the melted and solidified material <NUM> in a most part or a part of at least one of the first sheet layer 20A and the second sheet layer 20B as an adhesive as in the first adhesive structure or the third adhesive structure, it is preferable that a part of the first sheet layer 20A and the second sheet layer 20B is not melted since the bonded portions <NUM> are not hardened.

Note that when the first sheet layer 20A and the second sheet layer 20B are nonwoven fabrics, structures in which a part of the first sheet layer 20A and the second sheet layer 20B does not melt include a structure in which a core (including not only a core of a composite fiber but also a central part of a mono-component fiber) remains and a peripheral part thereof (including not only a sheath of the composite fiber but also a surface layer side part of the mono-component fiber) melts for all the fibers of the bonded portions <NUM>, or a structure in which some fibers do not melt at all and the rest of the fibers melt, or the core remains and the peripheral part thereof melts.

When the first sheet layer 20A and the second sheet layer 20B are bonded using the melted and solidified material <NUM> of the elastic sheet <NUM> as an adhesive as in the second welded structure and the third welded structure, the peel strength becomes high. The second welded structure can be manufactured by interposing the elastic sheet <NUM> between the first sheet layer 20A and the second sheet layer 20B, pressurizing/heating sites corresponding to the bonded portions <NUM>, and melting only the elastic sheet <NUM> under the condition that a melting point of at least one of the first sheet layer 20A and the second sheet layer 20B is higher than a melting point of the elastic sheet <NUM> and a heating temperature at the time of forming the bonded portions <NUM>.

On the other hand, the third welded structure can be manufactured by interposing the elastic sheet <NUM> between the first sheet layer 20A and the second sheet layer 20B, pressurizing/heating sites corresponding to the bonded portions <NUM>, and melting at least one of the first sheet layer 20A and the second sheet layer 20B and the elastic sheet <NUM> under the condition that a melting point of at least one of the first sheet layer 20A and the second sheet layer 20B is higher than a melting point of the elastic sheet <NUM>.

From this point of view, the elastic sheet <NUM> preferably has a melting point of about <NUM> to <NUM>, the first sheet layer 20A and the second sheet layer 20B preferably have a melting point of about <NUM> to <NUM>, particularly about <NUM> to <NUM>, and a difference between the melting point of the first sheet layer 20A and the second sheet layer 20B and the melting point of the elastic sheet <NUM> is preferably about <NUM> to <NUM>. In addition, the heating temperature is preferably set to about <NUM> to <NUM>.

In the second welded structure and the third welded structure, when the first sheet layer 20A and the second sheet layer 20B are nonwoven fabrics, the melted and solidified material <NUM> of the elastic sheet <NUM> may penetrate between fibers throughout the entire part of the first sheet layer 20A and the second sheet layer 20B in the thickness direction in the bonded portions <NUM> as illustrated in <FIG>. However, flexibility of the bonded portions <NUM> becomes high in a structure in which the material penetrates between the fibers to a middle in the thickness direction as illustrated in <FIG> or a structure in which the material hardly penetrates between the fibers of the first sheet layer 20A and the second sheet layer 20B as illustrated in <FIG>.

<FIG> illustrates an example of an ultrasonic sealing device suitable for forming the second welded structure and the third welded structure. In this ultrasonic sealing device, at the time of forming the bonded portions <NUM>, the first sheet layer 20A, the elastic sheet <NUM>, and the second sheet layer 20B are fed between an anvil roll <NUM> having protrusion portions 60a formed in a pattern of the bonded portions <NUM> on an outer surface and an ultrasonic horn <NUM>. In this instance, for example, by making a feed transfer speed of the elastic sheet <NUM> on the upstream side by a feed drive roll <NUM> and a nip roll <NUM> slower than a transfer speed on the downstream side of the anvil roll <NUM> and the ultrasonic horn <NUM>, the elastic sheet <NUM> is stretched to a predetermined stretch rate in an MD direction (machine direction, flow direction) along a path from a nip position by the feed drive roll <NUM> and the nip roll <NUM> to a sealing position by the anvil roll <NUM> and the ultrasonic horn <NUM>. The stretch rate of the elastic sheet <NUM> can be set by selecting a speed difference between the anvil roll <NUM> and the feed drive roll <NUM>, and can be set to, for example, about <NUM>% to <NUM>%. Reference character <NUM> denotes the nip roll.

The first sheet layer 20A, the elastic sheet <NUM>, and the second sheet layer 20B fed between the anvil roll <NUM> and the ultrasonic horn <NUM> are heated by ultrasonic vibration energy of the ultrasonic horn <NUM> while being pressed between the protrusion portions 60a and the ultrasonic horn <NUM> in a state of being stacked in this order, and only the elastic sheet <NUM> is melted, or at least one of the first sheet layer 20A and the second sheet layer 20B and the elastic sheet <NUM> are melted, thereby bonding the first sheet layer 20A and the second sheet layer 20B through the joint holes <NUM> simultaneously with formation of the joint holes <NUM> in the elastic sheet <NUM>. Therefore, in this case, the area ratio of the bonded portions <NUM> can be selected by selecting a size, a shape, a separation interval, and an arrangement pattern in a roll length direction and a roll circumferential direction of the protrusion portions 60a of the anvil roll <NUM>.

Even though a reason why the joint holes <NUM> are formed may not be clear, it is considered that the holes are opened when parts of the elastic sheet <NUM> corresponding to the protrusion portions 60a of the anvil roll <NUM> are melted and separated from the surroundings. In this instance, as illustrated in <FIG> and <FIG>, a part between adjacent joint holes <NUM> arranged in the stretchable direction ED in the elastic sheet <NUM> is cut from parts on both sides of the joint holes <NUM> in the stretchable direction and loses support on both sides in the stretchable direction. Thus, within a range in which continuity in the direction orthogonal to the contraction direction can be maintained, a center side in the direction LD orthogonal to the stretchable direction ED contracts until the center side balances with a center side in the stretchable direction, and the joint holes <NUM> expand in the stretchable direction ED.

As a constituent material of the first sheet layer 20A and the second sheet layer 20B, any sheet-shaped material can be used without particular limitation. However, it is preferable to use a nonwoven fabric from a viewpoint of air permeability and flexibility. A raw material fiber of the nonwoven fabric is not particularly limited. Examples of the raw material fibers can include synthetic fibers such as polyolefin-based fiber such as polyethylene and polypropylene, polyester-based fiber, and polyamide-based fiber, regenerated fibers such as rayon and cupra, natural fibers such as cotton, mixed fibers and conjugate fibers in which two or more of these are used, and the like. Further, the nonwoven fabric may be manufactured by any processing.

As a method of fiber bonding in the nonwoven fabric, it is possible to adopt any one of chemical means such as an adhesive or a solvent, physical means such as heating, or so-called entanglement. For example, it is possible to adopt a spun lace method, a spun bond method, a thermal bond method, a melt blown method, a needle punch method, an air through method, a point bond method, etc. When the nonwoven fabric is used, a basis weight thereof is preferably set to about <NUM> to <NUM>/m<NUM>. Further, a part or all of the first sheet layer 20A and the second sheet layer 20B may be a pair of layers in which a single material is folded back to face each other. For example, as in the illustrated example, in the waist end portions <NUM>, a constituent material located outside may be set to the second sheet layer 20B, the folded part 20C folded back to the internal surface side at a waist opening edge may be set to the first sheet layer 20A, and the elastic sheet <NUM> may be interposed therebetween. In other parts, a constituent material located inside may be set to the first sheet layer 20A, a constituent material located outside may be set to the second sheet layer 20B, and the elastic sheet <NUM> may be interposed therebetween. Naturally, the constituent material of the first sheet layer 20A and the constituent material of the second sheet layer 20B may be individually provided over the entire part in the front-back direction LD, and the elastic sheet <NUM> may be interposed between the constituent material of the first sheet layer 20A and the constituent material of the second sheet layer 20B without folding the constituent materials.

The elastic sheet <NUM> is not particularly limited, and may be a stretchable nonwoven fabric other than an elastic film as long as the sheet is made of a thermoplastic resin that elastically extends and contracts. In addition, as the elastic sheet <NUM>, it is possible to use not only a non-perforated sheet but also a sheet provided with a plurality of holes or slits for ventilation. In particular, it is preferable that the elastic sheet <NUM> has a tensile strength of <NUM> to <NUM> N/<NUM> in the width direction WD (stretchable direction ED and MD direction), a tensile strength of <NUM> to <NUM> N/<NUM> in the front-back direction LD (direction XD orthogonal to the stretchable direction and CD direction), a tensile elongation of <NUM> to <NUM>% in the width direction WD, and a tensile elongation of <NUM> to <NUM>% in the front-back direction LD. A thickness of the elastic sheet <NUM> is not particularly limited, and is preferably about <NUM> to <NUM>. In addition, an elastic nonwoven fabric may be provided on one side or both sides of an elastic film, which may be interposed as the elastic sheet <NUM> between the first sheet layer 20A and the second sheet layer 20B.

As illustrated in <FIG>, a part of the elastic sheet <NUM> located in the stretchable region <NUM> is printed with a first design <NUM> including design elements 51a, and a part of the elastic sheet <NUM> located in the non-stretchable region <NUM> is printed with a second design <NUM> including design elements 52a. The first design <NUM> and the second design <NUM> are the same when the stretchable region <NUM> and the non-stretchable region <NUM> are at the elongation at elastic limit. In addition, as a matter of course, the first design <NUM> and the second design <NUM> are visible from the outside of the outer body <NUM>.

To impart the first design <NUM> and the second design <NUM> to the elastic sheet <NUM>, in manufacturing, it is possible to use the elastic sheet <NUM> in which the first design <NUM> is preprinted on the part corresponding to the stretchable region <NUM>, and the second design <NUM> is preprinted on the part corresponding to the non-stretchable region <NUM>. In addition, prior to stretching of the elastic sheet <NUM> (on the upstream side of the feed drive roll <NUM> and the nip roll <NUM> in the manufacturing method of <FIG>), the first design <NUM> may be printed in-line on the part of the elastic sheet <NUM> corresponding to the stretchable region <NUM>, and the second design <NUM> may be printed on the part corresponding to the non-stretchable region <NUM>. A printing method is not particularly limited, and may be letterpress printing, gravure printing, offset printing, inkjet printing, etc. In order to improve the printability of the elastic sheet <NUM>, it is desirable to perform corona treatment on a printed surface.

The first design <NUM> may be provided not only on a portion of the part of the elastic sheet <NUM> located in the stretchable region <NUM> but also on the entire part of the elastic sheet <NUM> located in the stretchable region <NUM>. The second design <NUM> may be provided not only on a portion of the part of the elastic sheet <NUM> located in the non-stretchable region <NUM> but also on the entire part of the elastic sheet <NUM> located in the non-stretchable region <NUM>.

The first design <NUM> and the second design <NUM> are not particularly limited and may be, for example, a pattern for decoration (in addition to a polka dot pattern, a floral pattern, etc., a picture and a one-point character are included), function display such as a usage method, a usage assistance, or a size, mark display such as a manufacturer, a product name, or a characteristic function, or a combination of a plurality of these types. The design elements 51a, 52a, and 53a, including a third design <NUM> described below, are elements constituting a part that can be distinguished from other parts in the designs <NUM>, <NUM>, and <NUM> and are not particularly limited. For example, the design elements may be various geometric figures (for example, a circle in a polka dot pattern), hieroglyphics (a figure that represents a shape of an object by abstraction (for example, a single flower-shaped figure in a floral pattern), a picture (for example, a picture of a single flower in a floral pattern), a letter, or a combination of a plurality of these types. The design elements 51a, 52a, and 53a may be arranged at intervals, or may be arranged so as to be in contact with other design elements.

Characteristically, as illustrated in <FIG> by comparing (a) the spread state (state of being stretched in the width direction to the elongation at elastic limit), (b) the natural length state, and (c) the worn state (the stretch rate in the width direction is within a range of <NUM> to <NUM>%), a stretchable direction dimension 51x of the design elements 51a of the first design <NUM> when the stretch rate of the stretchable region <NUM> is <NUM>% or more (an upper limit is inevitably the elongation at elastic limit) is set to <NUM>% or more, particularly <NUM>% of the stretchable direction dimension 51x of the design elements of the first design <NUM> when the stretchable region <NUM> is at the elongation at elastic limit. This setting can be achieved by suppressing a difference between the stretch rate in the worn state and the elongation at elastic limit to some extent. To this end, the above-mentioned arrangement examples <NUM> to <NUM> are particularly suitable.

Note that as described above, "the same" with respect to the first design <NUM> and the second design <NUM> means that the design elements 51a and 52a have the same dimensions, shapes, orientations, arrangements, etc. However, it is natural that the areas of the designs <NUM> and <NUM>, the number of design elements 51a and 52a that change depending on the area, how the design elements 51a and 52a are discontinued, or missing may be different.

In this disposable wearable article, the first design <NUM> and the second design <NUM> are the same when the stretchable region <NUM> and the non-stretchable region <NUM> are at the elongation at elastic limit. This description merely means that uniform printing is applied to the part corresponding to the stretchable region <NUM> and the part corresponding to the non-stretchable region <NUM> in the elastic sheet <NUM>. In addition, in this disposable wearable article, the stretchable direction dimension 51x of the design elements 51a of the first design <NUM> when the stretch rate of the stretchable region <NUM> is <NUM>% or more, that is, in a general worn state is <NUM>% or more, particularly <NUM>% or more of the stretchable direction dimension 51x of the design elements 51a of the first design <NUM> when the stretchable region <NUM> is at the elongation at elastic limit. For this reason, there is little difference in appearance between the designs <NUM> and <NUM> in the stretchable region <NUM> and the non-stretchable region <NUM> during wearing. For example, when the first design <NUM> and the second design <NUM> are printed on the elastic sheet <NUM> to obtain a normal state in which the first design <NUM> and the second design <NUM> at the elongation at elastic limit are not deformed, a particularly preferable appearance is obtained during wearing.

In general, the disposable wearable article does not frequently have a stretchable structure as a whole. This description is similarly applied to the case of adopting the elastic sheet stretchable structure 20X. Specifically, in the example illustrated in <FIG>, etc., the elastic sheet stretchable structure 20X is not provided in a middle of the intermediate portion L of the outer body <NUM> in the front-back direction LD. In such a case, to add a design to a wider range, as in an example illustrated in <FIG> and <FIG>, it is preferable to provide the third design <NUM> including the design elements 53a and 53b to a non-stretchable sheet <NUM> other than the elastic sheet <NUM> extending from the non-stretchable region <NUM> to a region not having the elastic sheet stretchable structure 20X. The non-stretchable sheet <NUM> is not particularly limited as long as the third design <NUM> printed thereof is visible from the outer surface. In the underpants-type disposable diaper of the illustrated example, the non-stretchable sheet <NUM> may be a sheet (for example, the liquid impervious sheet <NUM> as in the illustrated example) closer to the outer side in the inner body <NUM>, and it is desirable that the third design <NUM> is printed on an outer surface thereof.

In the case of providing the third design <NUM>, to enhance integrity of the design, the third design <NUM> preferably includes design elements which are the same as the design elements of the first design <NUM> when the stretchable region <NUM> and the non-stretchable region <NUM> are at the elongation at elastic limit. In this way, the difference in appearance between the first design <NUM> and the third design <NUM> decreases in the worn state. Note that as described above, "the same" design elements with respect to the first design <NUM> and the third design <NUM> means that dimensions and shapes are the same, and colors and directions may be different.

As long as third design <NUM> includes design elements 53a which are the same as the design elements 51a of the first design <NUM> described above, the third design <NUM> may include only the same design elements 53a, or may include design elements 53b in which one or both designs are different from the other design.

In the case of providing the second design <NUM> and the third design <NUM> described above, in the non-stretchable region <NUM>, there is concern that the design elements 52a of the second design <NUM> of the elastic sheet <NUM> and the design elements 53a and 53b of the third design <NUM> of the non-stretchable sheet <NUM> may overlap with each other, resulting in a cluttered appearance. Therefore, as illustrated in <FIG>, it is proposed that the third design <NUM> is obtained by arranging the design elements 53a and 53b at intervals, a minimum value of a stretchable direction interval 53d between the design elements 53a and 53b arranged side by side in the stretchable direction in the third design <NUM> is set to be larger than (for example, about <NUM> to <NUM> times, in particular about <NUM> to <NUM> times) a minimum value of a stretchable direction dimension 52x of the design elements 52a of the second design <NUM>, and a minimum value of an orthogonal direction XD interval 53e of the design elements 53a and 53b arranged side by side in the orthogonal direction XD orthogonal to the stretchable direction in the third design <NUM> is set to be larger than (for example, about <NUM> to <NUM> times, in particular about <NUM> to <NUM> times) a minimum value of an orthogonal direction XD dimension 52y of the design elements 52a of the second design <NUM>. In this way, when the intervals 53d and 53e of the design elements 53a and 53b of the third design <NUM> are sufficiently sparse with respect to the sizes 52x and 52y of the design elements 52a of the second design <NUM>, the design elements 52a, 53a, and 53b rarely overlap each other, and clutter in appearance can be suppressed when compared to the opposite case. In the illustrated example, the intervals 53d and 53e of the design elements 53a and 53b of the third design <NUM> are set to be larger than the sizes 52x and 52y of the design elements 52a of the second design <NUM>. However, on the contrary, the intervals 52d and 52e of the design elements 52a of the second design <NUM> may be set to be larger than the sizes 53x and 53y of the design elements 53a and 53b of the third design <NUM>.

The dimensions and intervals of the design elements 51a, 52a, 53a, and 53b may be set as appropriate, and one example is as follows. Note that the following dimensions mean values when the stretchable region <NUM> and the non-stretchable region <NUM> are at the elongation at elastic limit (spread state).

The following terms in the specification have the following meanings unless otherwise specified in the specification.

Claim 1:
A disposable wearable article having an elastic sheet stretchable structure (20X) in which an elastic sheet (<NUM>) is stacked between a first sheet layer (20A) and a second sheet layer (20B), and the first sheet layer (20A) and the second sheet layer (20B) are bonded through joint holes (<NUM>) penetrating the elastic sheet (<NUM>) or with the elastic sheet (<NUM>) interposed therebetween at a plurality of bonded portions arranged at intervals,
wherein a region having the elastic sheet stretchable structure (20X) has a stretchable region (<NUM>) which contracts in a stretchable direction by a contraction force of the elastic sheet (<NUM>) and is stretchable in the stretchable direction, and a non-stretchable region (<NUM>),
a part of the elastic sheet (<NUM>) located in the stretchable region (<NUM>) is printed with a first design (<NUM>) including design elements (51a),
a part of the elastic sheet (<NUM>) located in the non-stretchable region (<NUM>) is printed with a second design (<NUM>) including design elements (52b),
the first design (<NUM>) and the second design (<NUM>) are the same when the stretchable region (<NUM>) and the non-stretchable region (<NUM>) are at an elongation at elastic limit, and
a stretchable direction dimension (51x) of the design elements of the first design (<NUM>) when a stretch rate of the stretchable region (<NUM>) is <NUM>% or more is <NUM>% or more of a stretchable direction dimension (51x) of the design elements of the first design (<NUM>) when the stretchable region (<NUM>) is at the elongation at elastic limit.