JPH08300499A - Porous sheet, manufacture thereof and absorptive article wherein the sheet is utilized - Google Patents

Abstract

PURPOSE: To give moisture permeability and water resistance to sheet and improve the strength of the sheet by a method wherein a plurality of ribs are provided in multiple rows at the predetermined intervals respectively in the longitudinal direction and in the lateral direction of the sheet on the surface of the sheet and, recessed parts are provided on the rear surface of the sheet at the positions corresponding to the ribs. CONSTITUTION: Porous sheet 1 consists of ribs 3 and 3' formed on a planar part 2 and recessed parts 4 and 4' provided on the rear surface of the planar part 2 in respectively corresponding to the ribs 3 and 3'. The ribs 3 and 3' are formed respectively in multiple rows in the longitudinal direction or the machine direction or the direction A and in the lateral direction or the cross direction or the direction normal to the direction A. The thickness (b) of the rib 3 in the machine direction is made to be 0.1-4 times as much as the thickness (a) of the planar part 2 and the pitch (c) is preferably set to be 100μ-50mm and the width (d) is preferably set to be 50μ-10mm. Further, the preferable ranges of the thickness (b) of the rib 3', of the pitch (e) and of the width (f) of the rib 3' are made to be equal to those of the ribs arranged in multiple rows in the machine direction. Furthermore, the thicknesses (b) of the ribs 3 and 3' are respectively and preferably to be 3-400μ and the thickness (a) of the planar part 2 is preferably 10-200μ. In addition, the depth (g) of the recessed part 4 is made to be 0.1-3 times as much as the thickness (a) of the planar part 2 and its width (h) is made to be 50μ-50mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous sheet, a method for producing the same, and an absorbent article, which have excellent sheet strength.
The present invention also relates to a porous sheet having excellent moisture permeability and water pressure resistance, a method for producing the same, and an absorbent article using the porous sheet.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
As the porous sheet, a sheet obtained by melt-mixing a crystalline polyolefin resin and an inorganic filler, shaping the sheet into a sheet, and then stretching the sheet in a uniaxial or biaxial direction, a crystalline polyolefin resin and melting of the resin An organic compounding agent that is miscible with the resin below and causes phase separation when cooled to a crystallization temperature of the resin or a temperature lower than that is melt-mixed and molded into a sheet, and then easily mixed with the organic compounding agent. A sheet obtained by extraction in a soluble extract, a sheet obtained by uniaxially or biaxially stretching with the organic compounding agent contained therein, or a sheet easily soluble in the organic compounding agent after stretching. Sheets and the like obtained by extraction in an extract are known. In addition, such a porous sheet is added with a plasticizer or the like for the purpose of flexibility and prevention of sharp noise (sound generated when the sheet is rubbed or rubbed), such as disposable diapers and sanitary napkins. Used as a backing material for absorbent articles.

However, in these absorbent articles,
A tape or the like for fixing the diaper is generally attached to the porous sheet as the backing material when the diaper is used, but in the conventional porous sheet, longitudinal uniaxial stretching, transverse uniaxial stretching or Even if it is obtained by either longitudinal or transverse stretching, neither the tensile strength nor the tear strength is sufficient, and the sheet is damaged during wearing or detaching without attaching the reinforcing tape to the fastening position of the fastening tape. There was a problem of doing. In addition, in order to reinforce the strength, Japanese Patent Publication No. 6-89
Japanese Patent Publication No. 163 and Japanese Patent Publication No. 6-89164 propose a method in which a sheet is provided with streaks in a striped pattern by embossing and then stretched in a direction intersecting with the streaks. It has not been possible to increase the tensile strength in a well-balanced direction, and it has not been possible to omit the reinforcing tape at the tape fastening portion.

Therefore, an object of the present invention is to provide a porous sheet which has moisture permeability and water resistance, is excellent in sheet strength, and has a good usability when used for absorbent articles and the like, and a method for producing the same. An object is to provide an absorbent article using the porous sheet.

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies in order to solve the above problems. As a result, the sheet has ribs in the MD direction and the CD direction, and the ribs are provided on the back surface. It has been found that a porous sheet having recesses can achieve the above object.

The present invention has been made based on the above findings, and has a plurality of ribs formed in multiple rows on the front surface of the sheet at predetermined intervals in the MD direction and the CD direction, and the back surface of the sheet. The present invention provides a porous sheet having a concave portion provided corresponding to the rib.

The present invention also provides, as a preferable method for producing the above-mentioned porous sheet, a resin from a T die on one surface of a lattice pattern-shaped member having a lattice pattern and a large number of openings formed by the lattice pattern. The composition is extruded and then vacuum-sucked from the other surface side of the lattice pattern-shaped member to obtain the MD direction and the CD.
Provided is a method for producing a porous sheet, which comprises forming a film having a rib in each of the directions and a recess corresponding to the rib, and then stretching the film in the MD direction, the CD direction, or the MD direction and the CD direction. To do.

Further, the present invention provides an absorbent article comprising a liquid-permeable surface material, a leak-proof back surface material, and an absorber arranged between them, wherein the surface material is the above-mentioned material. An absorbent article characterized by using a porous sheet.

First, the porous sheet of the present invention will be described in detail below. Examples of the material for forming the porous sheet of the present invention include the following resin compositions and the like. Composition: A composition comprising 100 parts by weight of a crystalline polyolefin resin, 30 to 400 parts by weight of a filler, and 0.1 to 20 parts by weight of a softening agent. Composition: 30 to 90 parts by weight of a crystalline polyolefin resin, 70 to 10 parts by weight of an organic compounding agent that is miscible with the crystalline polyolefin above the melting point of the crystalline polyolefin and dissolves, but causes phase separation below the melting point. Composition consisting of parts.

The above-mentioned crystalline polyolefin resin used in the above-mentioned composition is one having, as a main component, a monoolefin polymer or copolymer such as ethylene, propylene, butene, and linear low density polyethylene, homopolypropylene, Examples thereof include high density polyethylene, low density polyethylene, block copolymer polypropylene, random copolymer polypropylene, polybutene, ethylene-vinyl acetate copolymer, and mixtures thereof.

As the filler used in the composition, inorganic and organic fillers are used. Calcium carbonate, gypsum, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, sulfuric acid. Examples thereof include barium, calcium phosphate, aluminum hydroxide, zinc oxide, titanium oxide, alumina, mica, zeolite, carbon black, wood powder and pulp. Further, the calcium carbonate or the like may be surface-treated by hydrophobizing the surface with a fatty acid or a metal salt thereof.

Examples of the softening agent used in the composition include polyesters and hydrocarbon polymers. The polyester is a polyester having a polybasic acid or a polyhydric alcohol as a constituent component, and examples thereof include a trimethylolpropane / adipic acid / stearic acid polyester.

The crystalline polyolefin resin used in the composition is the same as the crystalline polyolefin resin used in the composition.

The above-mentioned organic compounding agent used in the above-mentioned composition is not particularly limited as long as it has the above-mentioned characteristics. Preferred examples thereof include triethylene glycol, dibutyl phthalate, and esters of phthalic acid, trimellitic acid, pyromellitic acid and / or aliphatic polybasic carboxylic acid with an alkyl alcohol.

Thus, the porous sheet of the present invention has a machine direction (MD direction) and a transverse direction (CD direction) on the surface of the sheet.
Each has a plurality of ribs formed in multiple rows at predetermined intervals, and has a recess provided on the back surface corresponding to the ribs. The "predetermined interval" can be represented by the pitch between the ribs. This pitch will be described later.

The porous sheet of the present invention will be described in more detail with reference to FIGS. 1 and 2. Here, FIG. 1 is an enlarged perspective view showing an enlarged main part of the porous sheet of the present invention, and FIG. 2 is a sectional view taken along the line AA of the porous sheet shown in FIG.

The porous sheet 1 of the present invention shown in FIGS. 1 and 2 has a flat portion 2, ribs 3 and 3'formed on the surface of the flat portion 2, and ribs on the back surface of the flat portion 2. The concave portions 4 and 4'are provided corresponding to the respective portions 3 and 3 '. The ribs 3 are formed in multiple rows along the MD direction of the porous sheet 1 (the direction of the arrow in FIG. 1), and the ribs 3 ′ are in the CD direction of the porous sheet 1 (as indicated by the arrow in FIG. 1). It is formed in multiple rows along the vertical direction). In addition, the concave portion 4 corresponds to the rib 3 in the MD of the porous sheet 1.
The recesses 4'are provided in multiple rows along the direction (direction of the arrow in FIG. 1), and the recesses 4'correspond to the ribs 3 '. Direction) is provided in multiple rows. That is, in the porous sheet of the present invention, the ribs 3 and 3'are formed so as to intersect each other and form a lattice-like pattern as a whole. Here, the intersecting angle Θ between the rib 3 and the rib 3 ′ is preferably 1 to 90 °, and more preferably a substantially right angle. Also, the ribs 3 and 3 ′ are
1 to 90 need not be parallel to MD or CD
Ribs may be formed in parallel in multiple rows at an angle of °.

The thickness b of the ribs 3 formed in multiple rows in the MD direction is preferably in the range of 0.1 to 4 times the thickness a of the flat surface portion 2, as shown in FIG. 0.3 ~
It is more preferable that the range is double. If the thickness b of the rib 3 is less than 0.1 times the thickness a of the flat surface portion 2, sufficient strength cannot be obtained, and if it exceeds 4 times, the flexibility is impaired, which is not preferable. The pitch c between the ribs 3 formed in multiple rows in the MD direction is 100 μ to 50 mm.
Is preferable, and 1 to 5 mm is more preferable. If the pitch c exceeds 50 mm, sufficient strength cannot be obtained, and if it is less than 100 μ, flexibility is impaired, which is not preferable. The width d of the ribs 3 formed in multiple rows in the MD direction is preferably 50 μ to 10 mm, more preferably 0.5 to 2 mm. If the above d is less than 50 μ, sufficient strength cannot be obtained and 1
If it exceeds 0 mm, flexibility is impaired, which is not preferable.

The thickness b of the ribs 3'formed in multiple rows in the CD direction, the pitch e between the ribs 3 ', and the ribs 3'.
The preferable range of the width f is the same as the preferable range of the rib formed in multiple rows in the MD direction described above, but different from the thickness b, the pitch c, and the width d of the rib 3 in the MD direction. They may be the same or the same. In addition, if it is less than the lower limit of the range or exceeds the upper limit of the range, it is not preferable for the same reason as the reason for the rib formed in multiple rows in the MD direction.

The widths d and f of the ribs 3 and 3'formed in multiple rows in the MD direction and the CD direction respectively depend on the line width of the lattice-pattern-shaped member and the stretching conditions described below. Since it depends on the case, it may not be clearly shown as shown in FIG. In that case, as shown in FIG. 3, the widths d and f of the ribs 3 and 3'are determined by using the rib width at a point half the distance between the top and bottom of the rib as a representative value. be able to.

The thickness b of each of the ribs 3 and 3'formed in multiple rows in the MD and CD directions is preferably 3 to 400 .mu.m. Further, the thickness a of the flat portion 2 is preferably 10 μ to 200 μ.

The recesses 4 and 4'provided in the porous sheet of the present invention are provided directly behind the ribs 3 and 3'corresponding to the ribs 3 and 3 ', respectively.
Therefore, like the ribs 3 and 3 ', the recesses 4 and 4'are also provided so as to intersect each other, and form a lattice-like pattern as a whole. The intersection angle Θ between the recess 4 and the recess 4 ′ is preferably in the same range as the intersection angle between the rib 3 and the rib 3 ′.

As shown in FIG. 2, the depth g of the concave portions 4 provided in multiple rows in the MD direction is the thickness a of the flat surface portion 2.
Is preferably 0.1 to 3 times the range of 0.3 to 1
More preferably, it is in the double range. Depth g of the recess 4
Is less than 0.1 times the thickness a of the flat portion 2, flexibility is impaired, and if it exceeds 3 times, sufficient strength cannot be obtained, which is not preferable. The pitch i between the recesses 4 provided in multiple rows in the MD direction is preferably 100 μm to 50 mm, and more preferably 1 mm to 5 mm. If the pitch i exceeds 50 mm, sufficient strength cannot be obtained, and if it is less than 100 μ, flexibility is impaired, which is not preferable. The width h of the recesses 4 provided in multiple rows in the MD direction is preferably 50 μ to 50 mm, and more preferably 0.5 to 2 mm. When h is less than 50 μm, flexibility is impaired, and
If it exceeds m, sufficient strength cannot be obtained, which is not preferable.

The depth j of the recesses 4'provided in multiple rows in the CD direction, the pitch l between the recesses 4 ', and the recesses 4'.
The preferred range of the width k is the same as the preferred range of the recesses 4 provided in multiple rows in the MD direction described above, but the depth g, the pitch i, and the width h of the recesses 4 in the MD direction are each. May be the same or different. Further, if the value is less than the lower limit of the range or exceeds the upper limit of the range, it is not preferable for the same reason as the reason for the recesses 4 provided in multiple rows in the MD direction described above.

The widths h and k of the recesses 4 and 4'provided in multiple rows in the MD direction and the CD direction depend on the line width and the stretching conditions of the lattice pattern-shaped member described below. Since it depends on the case, it may not be clearly shown as shown in FIG. In that case, as shown in FIG. 3, by setting the width of the concave portion at a point half the distance between the deepest portion of the concave portion and the peripheral surface portion as a representative value, the concave portions 4, 4 '
The widths h and k can be obtained.

Further, the depths g and j of the recesses 4 and 4'provided in multiple rows in the MD direction and the CD direction are preferably 3 to 200 .mu.m, respectively. In addition, the flat portion 2
The thickness a of is preferably 10 to 200 μ. Here, as shown in FIG. 2, the flat surface portion 2 usually has a concave mirror-like depression with both the front surface and the back surface slightly recessed, and the thickness a of the flat surface portion 2 means the most of the depression. The distance between deep parts, that is, the shortest distance.

The flat portion 2 may be concave mirror-like (having recesses on both sides) as shown in FIG. 2, or may be concave on one side and flat on the other side. The front surface and the back surface may both be parallel and planar.

Next, a preferred method for producing the porous sheet of the present invention will be described with reference to FIGS. 4, 5 (a) and 5 (b). Here, FIG. 4 is a schematic view showing a manufacturing apparatus used in the method for manufacturing a porous sheet of the present invention. 5 (a) is an enlarged plan view of the plain weave net as the lattice pattern-shaped member shown in FIG. 4, and FIG.
FIG. 6 is a BB cross-sectional view of the plain weave net shown in FIG.

First, the manufacturing apparatus 100 shown in FIG. 4 will be described. The manufacturing apparatus 100 includes an extruder 10 including a T die 11 for extruding the molten resin composition 1 ″,
Plain weave net 2 as a lattice pattern-shaped member for imparting a predetermined pattern to the resin composition 1 ″ extruded from the extruder 10.
0 and the suction nozzle 31 from the other side of the plain weave net 20.
Vacuum pump 3 for vacuum-sucking the resin composition 1 ″ through
0, a cooling roll 40 for cooling the film 1 ′ having a predetermined pattern (the ribs and the recesses) formed therein, and an MD stretching machine 60 for stretching the film 1 ′ passing through the cooling roll 40 in the MD direction. A CD direction stretching machine 70 for stretching the film 1'in the CD direction, a winding machine 80 for winding up the porous sheet 1 formed by stretching the film 1 ', and guide rollers 50, 51, 52. Consists of.

More specifically, the plain weave net 20 is used.
Has a lattice pattern 21 and a large number of apertures 22 formed by the lattice pattern 21.
Are arranged in parallel and in multiple rows (M of the porous sheet above).
A large number of wire rods 2 arranged in the direction corresponding to the D direction)
3 and a large number of wire rods 24 woven in the wire rods 23 so as to be orthogonal to the wire rods 23 and in multiple rows (toward the direction corresponding to the CD direction of the porous sheet). The plain weave net 20 is in the form of a belt conveyor so that the film 1'can be conveyed in the direction of the arrow. Here, the line pitches i ′ and l ′ of the nets 23 and 24 are the pitches i and l of the recesses 4 and 4 ′ described above.
And the line widths (line diameters) h ′ of the nets 23 and 24, which are optional depending on the pitches c and e of the ribs 3 and 3 ′.
k ′ is arbitrary depending on the widths h and k of the recesses 4 and 4 ′ described above and the widths d and f of the ribs 3 and 3 ′ described above. The material for forming the wires 23, 24 is not particularly limited as long as it does not deform even when the molten resin composition is placed, but metal or the like is preferably used.

The suction nozzle 31 is arranged above the conveyor-like plain weave net 20 so that vacuum suction can be performed while the resin composition 1 "extruded on the plain weave net 20 is in a molten state. On the side, it is arranged so as to abut on the other surface side of the plain weave net.
The size of the extruder 10 and the T-die 11 and the width and length of the plain weave net 20 are arbitrary depending on the size of the desired porous sheet.

In order to carry out the method for producing a porous sheet of the present invention, as shown in FIG. 4, the resin composition 1 ″ is extruded from the T die 11 onto one surface of the plain weave net 20. Further, vacuum suction is performed from the other surface side of the plain weave net 20 by the vacuum pump 30 to have ribs 3 and 3'in the MD direction and the CD direction, respectively, and the recesses 4 corresponding to the ribs 3 and 3 '. It can be carried out by forming a film 1 ′ having 4 ′ and then stretching the film 1 ′ in the MD direction, the CD direction, or the MD direction and the CD direction.

Specifically, the set temperature of the T die is 15
The temperature is preferably 0 to 240 ° C. The extruded resin composition 1 ″ is conveyed in the arrow direction and formed into a film by rolling the conveyor-like plain weave net 20 in the arrow direction. The plain weave net 20 at this time Of the film 1'corresponds to the take-up speed of the film 1 ', and the take-up speed is preferably 5 to 300 m / min. In the vacuum suction, the resin composition 1 "is in a molten state. The degree of vacuum V at this time is arbitrary depending on the desired thickness b of the ribs 3 and 3'and the desired thickness a of the flat surface portion 2. Then, by appropriately changing the degree of vacuum V, the thickness of the obtained porous sheet (thickness a of the flat surface portion), the thickness b of the ribs 3, 3'and the depths of the recesses 4, 4'in the porous sheet. g and j can be adjusted.

Then, the obtained film 1'is cooled by passing it through a cooling roll 40, and is supplied to a MD-direction stretching machine 50 and a CD-direction stretching machine 60 via a guide roller 50. Here, the MD direction stretching machine 60 and the CD direction stretching machine 70
If only one of the two is operated, a porous sheet stretched in only one of the MD and CD directions can be obtained, and if both are operated, the porous sheet stretched in both directions. You can get a sheet. Here, the above stretching can be performed according to a usual stretching method, and the stretching ratio is preferably 1.2 to 3 times in both the MD direction and the CD direction. Then, the stretched porous sheet 1 can be supplied to the manufacturing process of various molded products by winding it with the winder 80 through the guide rollers 51 and 52.

In this manner, the resin composition 1 "is extruded onto the plain weave net 20 and then vacuum suction is applied to the grid pattern 21 and the openings 2 of the plain weave net 20.
2, the unevenness (that is, the ribs 3 and 3 ′ and the recesses 4 and 4 ′) corresponding to the lattice pattern 21 and the flat surface portion 2 along the opening 22 are formed, and the porous sheet 1 is obtained. To be

In this embodiment, the plain weave net is used as an example of the lattice pattern-shaped member, but
Without being limited to this, a twill net, a plate having apertures surrounded by lattice-like ridges and ridges, and the like can be used.

As mentioned above, the porous sheet of the present invention is
The entire sheet is stretched, and the portion where the ribs and the concave portions are formed has lower moisture permeability than the portion where the ribs are not formed. As a whole, the sheet has high strength. Since it has ribs and recesses, it is a sheet that is strong in both tensile and tear strength in both longitudinal and lateral directions. Further, especially by having the above-mentioned recessed portion, the flexibility of the rib portion is not impaired. Therefore, the porous sheet of the present invention is suitable as a backing material for absorbent articles such as sanitary napkins and disposable diapers, and can also be used for filters, medical materials, and clothing materials.

Next, the absorbent article of the present invention will be described. The absorbent article of the present invention comprises a liquid-permeable front material, a leak-proof back material, and an absorber arranged between them. Such a configuration and the material for forming the surface material and the absorber and the like are the same as the conventionally known configuration and material. Thus, in the absorbent article of the present invention, the porous sheet of the present invention is used as the back material. The absorbent article of the present invention includes sanitary napkins, disposable diapers for adults or infants, incontinence pads, and the like, and the porous sheet is used in a desired shape depending on the application of the absorbent article. To be

[0039]

EXAMPLES Next, the porous sheet of the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

[Example 1 and Example 2] In Example 1, the following composition A was used, and in Example 2, the following composition B was used, and with the following extruder and plain weave net, the production apparatus shown in FIG. Then, it was molded under the following molding conditions to obtain a porous sheet.

(Composition) Composition A: Linear low-density polyethylene [trade name "Ultzex 2520F" manufactured by Mitsui Petrochemical Industries, Ltd.) 100 parts by weight Surface-treated calcium carbonate (1.1 μm) 150 parts by weight Polyester ( Trimethylolpropane / avidic acid / stearic acid = 2 mol / 1 mol / 4 mol 5 parts by weight Composition B: Polypropylene (M1 = 0.5, density = 0.91) 100 parts by weight Paraffin oil (density = 0. 87) (made by Idemitsu Kosan, trade name "PW3 80") 40 parts by weight

(Extruder) Extruder equipped with a T-die; 50-mm single-screw extruder (plain weave net) Line width (line diameter); 0.6 mm Line pitch; 1.8 mm

[Molding conditions]; set temperature; composition A ... 180 ° C. composition B ... 210 ° C. take-up speed; 16 m / min longitudinal stretching ratio: 1.6 times, transverse stretching ratio: 1.6 times

The shapes of the porous sheets obtained in Examples 1 and 2 were such that the thickness a of the flat surface portion was 40 μ and the thickness b of the rib was b.
Is 70 μ, the pitch c between the ribs is 1.8 mm, the rib widths d and f are 0.6 mm, the depths g and j of the recesses are 20 μ, the pitches i and l between the recesses are 1.8 mm, and the recesses are Has a width h, k of 0.4 mm. The following 1) to 4) tests were performed and evaluated on these porous sheets according to the following evaluation criteria. The results are shown in [Table 1].

[Evaluation Criteria] 1) Water vapor transmission rate: measured according to JIS ZO 208 2) Water pressure resistance: measured according to JIS L 1093B method 3) Tensile strength: direction of stretching and direction perpendicular to the stretching direction Sheets each having a width of 10 mm were subjected to a Tensilon tensile tester and measured at a chuck distance of 50 mm and a tensile speed of 300 mm / min. 4) Tear strength: Cut a piece of 60 mm × 30 mm so that its long side is equal to the stretching direction of the sheet, and further cut in parallel with the long side from the center of the above piece to one end of the short side with a razor blade. It was used as a sample. Then, using a Tensilon tensile tester, the two ends formed by cutting the sample were fixed to a chuck, the sample was T-shaped, and the tear measurement in the sheet stretching direction was performed at a tensile speed of 300 mm / min. The average load was determined from the obtained measurement chart and used as the tear strength.

[Comparative Example 1 and Comparative Example 2] A porous sheet having no ribs was obtained in the same manner as in Example 1 and Example 2, except that a normal T-die film forming machine not using a plain weave net was used. Got The obtained porous sheet was tested in the same manner as in Example 1 and Example 2. The results are shown in [Table 1].

[0047]

[Table 1]

[0048]

INDUSTRIAL APPLICABILITY The porous sheet of the present invention has moisture permeability and water pressure resistance, is excellent in sheet strength, and has a good feeling when used in absorbent articles and the like. Further, according to the method for producing a porous sheet of the present invention, the above-mentioned porous sheet can be easily produced. Further, since the absorbent article of the present invention uses the above-mentioned porous sheet as a backing material, even when there is no reinforcing tape in the tape fastening portion, even when it is adhesively fixed with a tape or the like during use, it is worn or removed. Moreover, the sheet is not torn, and the tape can be attached and removed at any position, which is excellent in usability.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view showing an enlarged main part of a porous sheet of the present invention.

2 is a cross-sectional view taken along the line AA of the porous sheet shown in FIG.

FIG. 3 is a cross-sectional view showing another example of the rib width measuring method.

FIG. 4 is a schematic view showing a manufacturing apparatus used in the method for manufacturing a porous sheet of the present invention.

5 (a) is an enlarged plan view of the plain weave net shown in FIG. 4, and FIG. 5 (b) is a BB cross-sectional view of the plain weave net shown in FIG. 5 (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Porous sheet 1'Film 1 '' Resin composition 2 Plane part 3,3 'Rib 4,4' Recess 10 Extruder 11 T die 20 Plain weave net 21 Lattice pattern 22 Open hole 23,24 Wire rod 30 Vacuum pump 31 Suction Nozzle 40 Cooling roll 50, 51, 52 Guide roller 60 MD direction stretching machine 70 CD direction stretching machine 80 Winding machine 100 Manufacturing apparatus

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B29K 105: 04 B29L 7:00 C08L 23:02

Claims (6)

[Claims] 1. A sheet has a plurality of ribs formed in multiple rows at predetermined intervals in the MD direction and the CD direction on the front surface, and has recesses provided on the back surface corresponding to the ribs. Porous sheet. 2. The porous sheet is stretched in the MD direction, the CD direction, or the MD direction and the CD direction, and the moisture permeability of a portion where the rib is not formed is a portion where the rib is formed. The porous sheet according to claim 1, which has a higher water vapor transmission rate. 3. The porous sheet according to claim 1, wherein the thickness of the rib is in the range of 0.1 to 4 times the thickness of the portion where the rib is not arranged. 4. The porous sheet according to claim 1, wherein the ribs have a width of 50 μm to 10 mm and the ribs have a pitch of 100 μm to 50 mm. 5. The method for producing a porous sheet according to claim 1, wherein a T-die is formed on one surface of the lattice pattern-shaped member having a lattice pattern and a large number of openings formed by the lattice pattern. The resin composition is extruded and further vacuum-sucked from the other surface side of the lattice pattern-shaped member to form a film having a rib in each of the MD direction and the CD direction and having a recess corresponding to the rib, Then, a method for producing a porous sheet in which the film is stretched in the MD direction, the CD direction, or the MD direction and the CD direction. 6. An absorbent article comprising a liquid-permeable surface material, a leak-proof back surface material, and an absorber arranged between them, wherein the surface material is the surface material. An absorbent article comprising a porous sheet.