JPH08281795A - Porous sheet, production thereof and absorbable article using porous sheet - Google Patents

Abstract

PURPOSE: To obtain a porous sheet having humidity permeability and water resistance, having no necessity of providing a reinforcing tape to a tape fastening surface, excellent in sheet strength in a degree capable of sticking the tape to the sheet at any position, having a good use feeling when used in an absorbable article and to provide the absorbable article using the porous sheet. CONSTITUTION: A porous sheet has a large number of ribs 3 formed thereto at an angle of 0-180 deg. with respect to the MD direction (shown by an arrow) of the sheet in many rows at a predetermined interval and is produced by supplying a resin compsn. to an annular die having many grooves to mold a film while rotating the die and stretching the film. An absorbable article is constituted of a liquid permeable surface material, a leak preventing rear surface material and the absorbing element arranged between them and the porous sheet is used as the rear surface material.

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 crystalline polyolefin resin and an inorganic filler are melt-mixed, molded into a sheet, and then stretched in a uniaxial or biaxial direction. The resin is miscible with, and an organic compounding agent that causes phase separation when cooled to a crystallization temperature of the resin or a temperature lower than that is melt-mixed and formed into a sheet, which is easily soluble in the organic compounding agent. A sheet obtained by extraction treatment in an extract, a sheet obtained by uniaxially or biaxially stretching while containing the organic compounding agent, or an extract which is easily soluble in the organic compounding agent after the stretching. Sheets and the like obtained by extraction treatment in liquid 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 What was obtained by any of the stretching treatments in the longitudinal and transverse directions had insufficient tensile strength and tear strength, and there was a problem that the sheet was damaged during wearing or detaching.
Further, in order to reinforce the strength, a reinforcing tape is attached to the tape fastening portion on the surface of the porous sheet, or a large amount of hot melt is used for reinforcement, but such reinforcement is used. There is a problem that the above-mentioned inconvenience and comfort are lacked. That is, there is a problem in that the position where the tape is attached is limited and the usability (mountability) is poor. In short, the conventional porous sheet does not satisfy both sufficient strength and good usability as the backing material of the absorbent article, and the development of a porous sheet satisfying both of these has been demanded. It is the current situation.

Therefore, it is an object of the present invention to have a sheet strength to such an extent that it has moisture permeability and water pressure resistance, it is not necessary to provide a reinforcing tape on the tape fixing surface, and the tape can be adhered to any position of the sheet. (EN) Provided are a porous sheet which is excellent in use and has a good feeling when used for an absorbent article and the like, a method for producing the same, and 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 and found that a porous sheet having ribs formed in a predetermined direction can achieve the above object. .

The present invention has been made based on the above findings, and is a porous sheet having a large number of ribs formed in multiple rows at predetermined intervals at an angle of 0 to 180 degrees with respect to the MD direction of the sheet. Is provided.

In the present invention, as a preferred method for producing the above-mentioned porous sheet, the resin composition is supplied to an annular die having a multi-row groove, a film is formed while rotating the die, and then the film is formed. The present invention provides a manufacturing method of stretching.

The present invention also provides an absorbent article comprising a liquid-permeable surface material, a leak-proof back surface material, and an absorber disposed between these materials, wherein the back surface material is the porous material. The present invention provides an absorbent article, which is characterized by using a flexible 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 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 which is miscible and soluble in the crystalline polyolefin above the melting point of the crystalline polyolefin but causes phase separation below the melting point. A composition comprising:

The above-mentioned polyolefin resin used in the above-mentioned composition is a resin containing, as a main component, a monoolefin polymer or copolymer such as ethylene, propylene or butene, linear low density polyethylene, homopolypropylene, high density. Examples thereof include 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 subjected to a surface treatment such as 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 polyolefin resin used in the composition is the same as the 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, and specifically, mineral oil such as liquid paraffin, synthetic lubricating oil, dioctyl phthalate, diethyl phthalate, tri-titanium Preferable examples include ethylene glycol, dibutyl phthalate, and esters of phthalic acid, trimellitic acid, pyromellitic acid and / or aliphatic polybasic carboxylic acid with an alkyl alcohol.

The porous sheet of the present invention has a predetermined angle of 0 to 180 degrees, preferably 30 to 150 degrees, and more preferably 45 to 135 degrees with respect to the longitudinal direction (MD direction) of the sheet. It has a plurality of ribs formed in multiple rows at intervals. 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 plan view showing a main part of the porous sheet of the present invention in an enlarged manner, and FIG. 2 is a sectional view taken along line I-I of the porous sheet shown in FIG.

The porous sheet 1 of the present invention shown in FIGS. 1 and 2 comprises a flat portion 2 and a rib 3 formed on the flat portion 2, and the rib 3 is in the MD direction of the sheet (FIG. The angle Q with respect to the arrow direction 1) is in the range of 0 to 180 degrees.

Further, as shown in FIG. 2, the thickness b of the rib 3 is preferably in the range of 0.1 to 4 times, and in the range of 0.2 to 1 times, the thickness a of the flat surface portion 2. It is more preferable that there is. The thickness b of the rib 3 is 0.1 of the thickness a of the flat surface portion 2.
If it is less than twice, sufficient strength cannot be obtained, and if it exceeds 4 times, flexibility is impaired, which is not preferable. The pitch c between the ribs 3 is preferably 50 μ to 50 mm, more preferably 1 to 5 mm. If the pitch c is less than 50 μ, the flexibility is impaired and 50 mm
If it exceeds, it is not preferable because sufficient strength cannot be obtained. Further, the width d of the rib 3 is preferably 50 μ to 10 mm, more preferably 0.5 to 2 mm.
If the width d is less than 50 μ, sufficient strength cannot be obtained, and if it exceeds 10 mm, flexibility is impaired, which is not preferable. Further, since the rib width d depends on the groove shape of the die described below, it may not be clearly shown as shown in FIG. In that case, as shown in FIG. 3, the rib width d can be obtained by using the rib width at a point half the distance between the top and bottom of the rib as a representative value.

The thickness of the flat portion 2 is 10 to 200 μm.
Is preferable, and the thickness of the rib 3 is preferably 3 to 200 μ.

Next, a preferred method for producing the porous sheet of the present invention will be described in detail. To carry out the method for producing a porous sheet of the present invention, by supplying a resin composition to an annular die having a multi-row groove, forming a film while rotating the die, and then stretching the film. It can be carried out.

The above manufacturing method will be described in more detail with reference to FIGS. Here, FIG. 4 is a schematic view showing an apparatus for carrying out the manufacturing method of the present invention, and FIG.
FIG. 5B is a cross-sectional view showing the main part of the annular die, and FIG.
5A is a plan view showing an outer ring and an inner cylinder of the annular die shown in FIG. 5A, and FIG. 5C is a sectional view showing a main part of another example of the annular die. d) is shown in FIG.
FIG. 3 is a plan view showing an outer ring and an inner cylinder of the annular die shown in FIG.

In the above manufacturing method, as shown in FIG. 3, the resin composition is used in the form of an annular die 11 to which a multi-row groove is applied.
The resin composition is fed into the annular die 11 and blown up, and the annular die 11 is rotated in the direction of arrow A to be formed at an arbitrary angle with respect to the MD direction. Film having a multi-row rib 1 '
Is blow-molded, and the film 1 ′ is supplied to the guide plate 30 while being cooled by the air ring 20, and the film 1 ′ is stretched by the stretching roller 31 in either longitudinal or lateral direction (uniaxial) or both longitudinal and lateral directions (biaxial). It can be performed by stretching. Further, the stretched porous sheet 1 of the present invention can be wound by a winding roller 33 via a plurality of guide rollers 32.

At this time, by selecting the size of the extrusion slit and the depth of the groove in the annular die 11, the rib having the desired thickness described above can be formed.
Further, by selecting the pitch of the groove, the rib can be formed with the desired pitch described above.

The size of the extruder and the size of the annular die are arbitrary depending on the size of the desired porous sheet. Further, the set temperature in the inflation molding is preferably 150 to 240 ° C., and the take-up speed is preferably 5 to 40 m / min. Also,
The stretching ratio in the above stretching is preferably 1.2 to 3 times.

When the ribs are attached to the outer surface of the bubble during film forming, as shown in FIGS. 4 (a) and 4 (b), the outer ring 12 of the annular die 11 is formed.
A groove may be provided, and when the rib is attached to the inner surface of the bubble during film formation, the rib shown in FIG.
And, as shown in (d), a groove may be provided in the inner cylinder 13 of the annular die 11. Furthermore, ribs can be applied to both the inside and outside of the bubble at the same time.

As mentioned above, the porous sheet of the present invention comprises:
The entire sheet is stretched, and the portion where the rib is formed has lower moisture permeability than the portion where the rib is not formed, and although it is a porous sheet as a whole, it has high-strength ribs. Therefore, the sheet is strong in both tensile and tear strength in both longitudinal and lateral directions. 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

[0028]

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 The following compositions A and B were inflation-molded under the following molding conditions using an extruder having an annular die provided with the following grooves, and stretched to obtain a porous sheet.

(Composition) Composition A: Linear low-density polyethylene [trade name, "Ultzex 2520F" manufactured by Mitsui Petrochemical Co., Ltd.) 100 parts by weight Surface-treated calcium carbonate (1.1 μm) 150 parts by weight Polyester (Trimethylolpropane / Avidin 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) (Idemitsu Petrochemical, trade name "PW 380") 40 parts by weight

(Extruder) Extruder 50 mm single screw extruder Annular die 200 mm rotating die Groove width 0.35 mm Groove pitch 0.90 mm Groove height 0.6 mm Groove angle 50 degrees

[0032]

The shape of the porous sheet obtained in this example is such that the thickness a of the flat portion is 35 μ, the thickness b of the rib is 7 μ, the pitch c between the ribs is 1.8 mm, and the rib width is 0.6 mm. is there. The porous sheet was tested and evaluated according to the following evaluation criteria. The results are shown in [Table 1]. For composition A, the rib angle was set to 0 ° to produce a porous sheet, and for composition B, the rib angle was set to 0 °, 4 °
The porous sheet was manufactured with three angles of 5 degrees and 90 degrees.

(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: Stretching direction: 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] Example 1 was repeated except that a die having no groove was used as the annular die.
A porous sheet having no ribs was obtained in the same manner as in (1) and tested in the same manner as in Example 1. The results are shown in [Table 1].

[0036]

[Table 1]

[0037]

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 plan view showing an enlarged main part of a porous sheet of the present invention.

FIG. 2 is a cross-sectional view taken along the line II 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 an apparatus for carrying out the manufacturing method of the present invention.

5 (b) is a plan view showing an outer ring and an inner cylinder of the annular die shown in FIG. 5 (a), and FIG. 5 (c) is a plan view showing the inner ring.
5 is a cross-sectional view showing a main part of another example of the annular die, and FIG.
FIG. 5D is a plan view showing an outer ring and an inner cylinder of the annular die shown in FIG. 5C.

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[Procedure amendment]

[Submission date] September 4, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

In the above manufacturing method, as shown in FIG. 4 , the resin composition is formed into an annular die 11 to which a multi-row groove is applied.
The resin composition is fed into the annular die 11 and blown up, and the annular die 11 is rotated in the direction of arrow A to be formed at an arbitrary angle with respect to the MD direction. Film having a multi-row rib 1 '
Is blow-molded, and the film 1 ′ is supplied to the guide plate 30 while being cooled by the air ring 20, and the film 1 ′ is stretched by the stretching roller 31 in either longitudinal or lateral direction (uniaxial) or both longitudinal and lateral directions (biaxial). It can be performed by stretching. Further, the stretched porous sheet 1 of the present invention can be wound by a winding roller 33 via a plurality of guide rollers 32.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

When the ribs are attached to the outer surface of the bubble during film forming, as shown in FIGS. 5 (a) and 5 (b), the outer ring 12 of the annular die 11 is formed.
May be granted a groove in, also when attaching the rib to the bubble of the inner surface at the time of film molding, and FIG. 5 (c)
And, as shown in (d), a groove may be provided in the inner cylinder 13 of the annular die 11. Furthermore, ribs can be applied to both the inside and outside of the bubble at the same time.

[Procedure amendment]

[Submission date] September 4, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

FIG . 5 (a) is a cross-sectional view showing a main part of an annular die.
, And the FIG. 5 (b) is a plan view showing the outer ring and the inner cylinder of the circular die shown in FIG. 5 (a), FIG. 5 (c),
5 is a cross-sectional view showing a main part of another example of the annular die, and FIG.
FIG. 5D is a plan view showing an outer ring and an inner cylinder of the annular die shown in FIG. 5C.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location B29L 7:00 C08L 23:02

Claims (5)

[Claims] 1. A porous sheet having a large number of ribs formed in multiple rows at predetermined intervals at an angle of 0 to 180 degrees with respect to the MD direction of the sheet. 2. 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. 3. 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. 4. The method for producing a porous sheet according to claim 1, wherein the resin composition is supplied to an annular die having multiple grooves, a film is formed while rotating the die, and then the film is formed. A method of stretching. 5. An absorbent article comprising a liquid-permeable surface material, a leak-proof backing material, and an absorber arranged therebetween, wherein the backing material is porous. An absorbent article characterized by using a permeable sheet.