JP3526971B2 - Porous sheet and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous sheet and a method for producing the same, and more particularly to a porous sheet having excellent moisture permeability and leakproofness and strength, and a supple texture, and a method for producing the same. is there.

[0002]

2. Description of the Related Art A sheet obtained by melt-kneading a filler in a polyolefin resin and molding the same is stretched uniaxially or longitudinally and biaxially to obtain a sheet.
There have been many attempts to obtain a porous sheet. In the porous sheet obtained by the uniaxial stretching,
There is a problem that the anisotropy of strength, that is, the tear strength in the stretching direction and the tensile strength in the transverse direction are extremely weak. As a method of improving the anisotropy of the strength, there is a method of stretching at a draw ratio as low as possible, but there is a problem that a uniform stretched sheet cannot be obtained by drawing at a draw ratio of low. In addition, although the problem of strength anisotropy is solved by biaxially stretching the sheet,
This causes a problem that the stretchability is remarkably deteriorated.

In Japanese Examined Patent Publication No. 60-26009, a tubular film of a thermoplastic resin containing an inorganic filler is uniaxially pre-stretched in the longitudinal direction, then biaxially stretched in the transverse and longitudinal directions, and then cooled. A method for producing a porous film comprising the above is described. However, the manufacturing method has problems that not only the operation is complicated, but also the labor for controlling the uniaxial pre-stretching is required.

Further, with a sheet formed from a resin composition consisting of a polyolefin resin and a filler, it is impossible to obtain a porous sheet having a supple texture even when stretched. As a means for solving such a problem, it has been proposed to add some additives including a liquid hydrocarbon as a third component to a resin composition composed of a polyolefin resin and a filler. For example, as a third component for improving the above problems, JP-A-58-15538 discloses liquid polybutadiene, liquid polybutene and terminal hydroxy liquid polybutadiene, and JP-A-58-14992.
No. 5, the liquid polyisoprene rubber is disclosed in Japanese Patent Publication No. 6-
JP 62795 and JP 62-280235 disclose specific polyester mixtures and monoesters.

However, even with these improved techniques, it was not possible to obtain a porous sheet having both excellent moisture permeability and tear strength in the stretching direction. In particular, when it is used as a constituent material that shares a fastening function with a fastening tape, such as a moisture-permeable leakproof sheet for absorbent articles such as disposable diapers, if the tear strength in the longitudinal direction is weak, the fastening tape will be Since the stress is locally concentrated on the surrounding area of the fastening tape of the moisture-permeable leak-proof sheet during peeling and use, the tearing of the surrounding area of the fastening tape is likely to occur. It cannot be used as a moisture-permeable leak-proof sheet for absorbent articles such as diapers.

Accordingly, an object of the present invention is to provide a porous sheet having a soft and supple texture and having a necessary and sufficient strength when used as a moisture-permeable leakproof sheet for absorbent articles such as disposable diapers. It is to provide a manufacturing method.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors formed a melt-kneaded product of a specific resin composition into a sheet, and embossed the sheet with a specific embossing. It was found that a porous sheet stretched by a roll can achieve the above object.

The present invention has been made based on the above findings, and a sheet formed from a melt-kneaded product of a resin composition (a) containing a polyolefin resin and a filler as essential components,
A pair of embossing rolls in which a convex portion of one roll is engraved with a pattern corresponding to a concave portion of the other roll, and the pattern is a striped pattern in a direction orthogonal to the roll axis. The present invention provides a porous sheet characterized by being obtained by stretching the film in the transverse direction by 1.05 times or more and then in the longitudinal direction.

Further, according to the present invention, a sheet formed from a melt-kneaded product of a resin composition (b) containing a polyolefin resin and a thermoplastic resin incompatible with the polyolefin resin as essential components is used for one roll. A pair of embossing rolls in which a convex portion is engraved with a pattern so as to correspond to the concave portion of the other roll, and the pattern is a striped pattern in a direction perpendicular to the roll axis. The present invention provides a porous sheet obtained by performing a stretching treatment and then a longitudinal stretching treatment.

Further, according to the present invention, a melt-kneaded product of the resin composition (a) or the resin composition (b) is formed into a sheet, and the sheet has a convex portion of one roll and a concave portion of the other roll. A pair of embossing rolls in which a pattern is engraved so as to correspond to the above, and the pattern is a striped pattern in a direction perpendicular to the roll axis. Then, the present invention provides a method for producing a porous sheet, which comprises subjecting the film to 1.2-4.0 times stretching in the machine direction.

First, the porous sheet of the present invention will be described in detail. The porous sheet of the present invention is a porous sheet obtained by subjecting a sheet molded from a melt-kneaded product of a resin composition to a stretching treatment, and the resin composition contains a specific polyolefin resin and a specific filler as essential components. Is a resin composition (a) or a resin composition (b) containing a specific polyolefin resin and a thermoplastic resin incompatible with the polyolefin resin as essential components, and a plasticizer, a lubricant, etc., if necessary. It is a resin composition containing.

Examples of the specific polyolefin resin used in the resin composition (a) in the present invention include homopolymers or copolymers of olefins and copolymers of olefins with other monomers. As the polyolefin resin, polyethylene resin or polypropylene resin can be preferably used. Among these, for example, high-density polyethylene resin, low-density polyethylene resin and linear low-density polyethylene resin are preferably used, and among them, the density is 0.910 to 0.940 g.
/ Cm ³ melt flow rate (MFR) 0.1-5
A linear low density polyethylene resin of g / 10 min is particularly preferably used.

The resin composition (a) has a crystalline polyolefin resin and a crystallinity of 5 to 2 by X-ray.
It was 5%, and density of 0.86~0.90g / cm ³
When the resin composition containing the (ethylene-α-olefin) copolymer as an essential component is used, flexibility is imparted to the obtained porous sheet, and particularly, the tensile strength and the tear strength are excellent, and therefore it is preferably used. . In the present invention, the above polyolefin resins may be used alone or in combination of two or more.

The above (ethylene-α-olefin)
When the copolymer is blended, the blending amount is generally preferably 20 to 100 parts by weight with respect to 100 parts by weight of the crystalline polyolefin resin. In addition, the above-mentioned polyolefin resin may be blended with a resin other than the above-mentioned polyolefin resin as long as the characteristics of the above-mentioned polyolefin resin are not lost.

In the present invention, the specific filler used in the resin composition (a) is not particularly limited as long as it is a filler usually mixed in rubber or plastic. As the filler, for example, calcium carbonate, gypsum, calcium sulfate, calcium phosphate, magnesium carbonate, magnesium sulfate, hydrated silicic acid, silicic acid anhydride, soda ash, sodium chloride, sodium sulfate, barium sulfate, talc, clay, Inorganic fillers such as various cements, volcanic ash, shirasu, titanium oxide, iron oxide and carbon black; various metal powders; other inorganic substances and organic metal salts mainly composed of inorganic substances. Further, a resin obtained by crosslinking a thermoplastic resin such as a phenol resin, an epoxy resin and a polyacrylic acid ester by radiation or the like; or a polymer such as a resin having a melting temperature higher than the molding temperature of the porous sheet can also be used. In the present invention, the above fillers may be used alone or in combination of two or more.

The average particle size of the filler is preferably 50.
It is not more than μm, more preferably 0.05 to 30 μm, most preferably 0.1 to 5 μm. When the average particle size exceeds 50 μm, the density of the pores of the resulting porous sheet is lowered, and when the average particle size is less than 0.05 μm, stretching unevenness easily occurs and a good porous sheet cannot be obtained. There is.

The filler is preferably surface-treated with a surface-treating agent from the viewpoint of uniform dispersibility in the resin. The surface treatment agent is not particularly limited, and examples thereof include compounds such as fatty acids or metal salts thereof that can make the surface of the filler hydrophobic.

The above resin composition (a) used in the present invention
The mixing ratio of the polyolefin resin and the filler in the above is 100 parts by weight of the polyolefin resin,
The amount of the filler is preferably 50 to 400 parts by weight, more preferably 60 to 250 parts by weight. If the blending ratio of the filler exceeds 400 parts by weight, it becomes difficult to form and stretch the sheet-like material, and if it is less than 50 parts by weight, the number of communicating holes of the obtained porous sheet becomes small and the moisture permeability becomes low.

A third component may be added to the resin composition (a) in order to impart a supple texture, a reduction in noise, a slipping property, and an improvement in stretchability. As the third component, it is possible to use a plasticizer or a lubricant which is usually mixed with rubber or plastic, and for example, a monoester composed of a fatty acid and an aliphatic alcohol, an aromatic carboxylic acid and an aliphatic alcohol. Monoester or polyester, polyester consisting of aliphatic polycarboxylic acid and polyalcohol, polyester consisting of monocarboxylic acid and / or polycarboxylic acid and monoalcohol and / or polyalcohol, part of alcohol and / or carboxylic acid Leftover ester or polyester, aliphatic amide, aromatic amide, fatty acid metal soap, aromatic carboxylic acid metal soap, butadiene oligomer, butene oligomer, isobutylene oligomer, isoprene oligomer, petroleum resin, coumarone resin, ketone resin, chlorination paraffin, Recone oil, liquid paraffin, polyethylene wax.

When the third component is added to the resin composition (a), the addition amount is the above-mentioned polyolefin resin 100.
It can be added preferably in an amount of 0 to 20 parts by weight, more preferably 1 to 15 parts by weight, based on parts by weight.

As the specific polyolefin resin used in the resin composition (b) in the present invention, homopolymers or copolymers of olefins such as ethylene and propylene can be used without any particular limitation. When the melting temperature of the soluble thermoplastic resin is close to the sheet film forming temperature, by controlling the melt viscosity of the polyolefin resin and the thermoplastic resin, the thermoplastic resin during the sheet film formation is controlled. It is important to reduce resin shear. In such a case, the desired melt viscosity can be obtained by adding a softening agent. As the softening agent, known softening agents are used without particular limitation.

The dispersed particle size of the thermoplastic resin is
It is preferably 50 μm or less, more preferably 0.05 to 3
It is 0 μm, most preferably 0.1 to 5 μm. If the dispersed particle size exceeds 50 μm, the density of the pores of the resulting porous sheet decreases, and if the dispersed particle size is less than 0.05 μm, uneven stretching tends to occur and a good porous sheet may not be obtained. is there.

In the present invention, the resin which is incompatible with the polyolefin resin used in the resin composition (b) is not particularly limited, but examples thereof include general-purpose polystyrene, high-impact polystyrene and acrylonitrile-styrene copolymer. , Butadiene-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, polyester resins such as polymethylmethacrylate, polyethylene terephthalate, polybutene terephthalate, polyamide resins such as nylon 6, nylon 66, polycarbonate, acrylonitrile, and the like. And modified products thereof. In the present invention, the above resins may be used alone or in combination of two or more.

The above resin composition (b) used in the present invention
The blending ratio of the polyolefin resin and the thermoplastic resin in is preferably 10 to 100 parts by weight, and more preferably 20 to 100 parts by weight with respect to 100 parts by weight of the polyolefin resin. When the blending ratio of the thermoplastic resin exceeds 100 parts by weight, the continuous phase resin (the above polyolefin resin) and the dispersed phase resin (the above thermoplastic resin) of the sheet undergo phase inversion, which is not preferable. On the other hand, if it is less than 10 parts by weight, the number of communicating holes in the moisture permeable region of the resulting porous sheet will be small, so that the moisture permeability may be reduced.

A thermoplastic elastomer may be added to the thermoplastic resin in order to facilitate control of dispersibility. The thermoplastic elastomer is not particularly limited, but examples thereof include styrene elastomer, olefin elastomer, urethane elastomer, ester elastomer, amide elastomer, 1-2 polybutadiene elastomer, trans 1,4-polyisoprene elastomer and the like. Can be mentioned.
In the present invention, when the above-mentioned thermoplastic elastomer is added to the above-mentioned thermoplastic resin, the above-mentioned thermoplastic elastomers can be used alone or in combination of two or more kinds. In the present invention, when the thermoplastic elastomer is added to the thermoplastic resin, the blending amount thereof is preferably 0.05 to 3 with respect to 100 parts by weight of the mixture of the polyolefin resin and the resin incompatible with the polyolefin resin.
0 parts by weight.

Further, in the above-mentioned thermoplastic resin, in order to control the stretching opening, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid are used. Acid ester copolymer, ethylene-acrylic acid-acrylic acid ester copolymer, ethylene-methacrylic acid-acrylic acid ester copolymer, ethylene-vinyl acetate-glycidyl methacrylate copolymer, ethylene-maleic anhydride-acrylic acid It is possible to add an ethylene-based copolymer resin composed of one kind or a mixture of two or more kinds selected from ester copolymers. In the present invention, when the resin is added to the thermoplastic resin, the amount thereof is preferably 1 to 30 parts by weight with respect to 100 parts by weight of the mixture of the polyolefin resin and a resin incompatible with the polyolefin resin. .

Further, a softening agent can be added to the resin composition (b) in order to control the melt viscosity and the draw openability of the polyolefin resin. As the softening agent, a plasticizer or a lubricant which is usually mixed with rubber or plastic can be used. For example, a monoester composed of a fatty acid and an aliphatic alcohol, an aromatic carboxylic acid and an aliphatic alcohol is used. Monoester or polyester, polyester consisting of aliphatic polycarboxylic acid and polyalcohol, polyester consisting of monocarboxylic acid and / or polycarboxylic acid and monoalcohol and / or polyalcohol, part of alcohol and / or carboxylic acid Leftover ester or polyester, aliphatic amide, aromatic amide, fatty acid metal soap, aromatic carboxylic acid metal soap, butadiene oligomer, butene oligomer, isobutylene oligomer, isoprene oligomer, petroleum resin, coumarone resin, ketone resin, chlorination paraffin, Recone oil, liquid paraffin, polyethylene wax.

When the softening agent is added to the resin composition (b), the addition amount is the above-mentioned polyolefin resin 10
It is preferably 0 to 20 parts by weight, more preferably 1 to 15 parts by weight, based on 0 parts by weight.

The porous sheet of the present invention is a porous sheet obtained by subjecting a sheet formed from the melt-kneaded product of the resin composition (a) or the resin composition (b) to a stretching treatment. The above "molding" and "stretching" will be described in detail in the description of the "manufacturing method" described later.

The porous sheet of the present invention is suitable as a backing material for absorbent articles such as disposable diapers, and is also laminated with woven cloth, non-woven cloth, paper, etc. for waterproofing, cold protection, germ proofing, tents, and bedding. , Wrapping bag, base material of Hap material for clothing and medical use, freshness preservation, life preservation of small animals and seeds, packaging material for decay prevention, ripening material for fruits, shading material, filtration, separation membrane for diffusion prevention, etc. It can be used as a material.

Next, the method for producing the porous sheet of the present invention, which is a preferable method for producing the porous sheet of the present invention, will be described in detail. To manufacture the porous sheet of the present invention, first, a melt-kneaded product of the resin composition (a) or the resin composition (b) is molded into a sheet. Here, the melt-kneaded product is obtained by premixing with a commonly used Henschel mixer, super mixer, or the like, and then kneading with a usual method such as a Banbury mixer, a mixing roll, a single-screw extruder or a twin-screw extruder. You can

Next, the melt-kneaded product is formed into a sheet. The above-mentioned molding is a commonly used inflation method,
It can be performed by molding by a T-die method or the like.

Then, the sheet is stretched. The sheet is first stretched in the transverse direction by an embossing roll and then in the longitudinal direction.

The transverse stretching in the above manufacturing method will be described in more detail with reference to FIGS. Here, FIG.
FIG. 2 is a schematic view showing an example of an apparatus 10 for performing a transverse stretching treatment in the method for producing a porous sheet of the present invention, and FIG. 2 is an embossing roll used in the method for producing a porous sheet of the present invention. It is the II-II sectional view taken on the line of 14 and 14 '. To stretch the sheet in the production method of the present invention,
First, the sheet 12 is embossed with rolls 14 and 14 '.
To stretch in the transverse direction. The embossing roll 14,
As shown in FIG. 2, 14 'is a pair of embossing rolls in which a pattern is engraved so that the convex part of one roll corresponds to the concave part of the other roll, and the pattern is relative to the roll axis. A pair of embossing rolls having a vertical stripe pattern. The sheet 12 is conveyed in the direction of the arrow while passing between the pair of embossing rolls 14 and 14 ′ to perform stretching in the lateral direction.

The pair of embossing rolls 14 and 14 '.
Is generally a combination of hard iron rolls and hard iron rolls,
There are combinations of hard iron rolls and paper rolls, and combinations of hard iron rolls and cotton rolls. Further, the sheet 12 stretched in the lateral direction is taken up by a winding roller (not shown).
It can be wound up with.

In the transverse stretching treatment, the sheet can be heated as required in the same manner as the ordinary stretching treatment of the sheet, or the sheet is preheated prior to the transverse stretching treatment. You can also leave it. Also, when inserting the sheet 12 between the embossing rolls 14, 14,
It is also possible to dispose a pressing roll (not shown) in order to prevent the sheet 12 from wrinkling and the sheet 12 from shifting.

FIG. 3 is a schematic view showing another apparatus 30 for carrying out the transverse stretching treatment in the method for producing a porous sheet of the present invention, and FIG. 4 is a method for producing a porous sheet of the present invention. IV-of embossing rolls 34, 34 'used for
FIG. 5 is a cross-sectional view taken along the line IV, and FIG.
It is a principal part enlarged view of the cross section of the V line.

The embossing rolls 34, 34 'are shown in FIG.
As shown in Fig. 2, a convex portion of one roll is a pair of embossing rolls in which a pattern is engraved so as to correspond to the concave portion of the other roll, and the pattern is a striped pattern in a direction perpendicular to the roll axis. A pair of embossing rolls, sheet 3
While conveying 2 in the direction of the arrow, a pair of embossing rolls 3
Stretching in the transverse direction is carried out by passing between 4, 34 '. In the device 30, the embossing roll 3
When inserting the seat 32 between the 4'and 34 '
In order to prevent wrinkles from being generated and the sheet 32 from being displaced, press rolls 36 and 36 'are arranged. The sheet 32 stretched in the lateral direction can be wound by a winding roller (not shown). The material of the embossing roll in the device 30 is the same as that in the device 10.

The embossing roll 14, 14 'or 3
Stretching in the transverse direction of the sheet carried out by 4, 34 ', the is the draw ratio is 1.05 times or more, it is good preferable is 1.1 times or more. The transverse stretching treatment,
The purpose is to improve the mechanical properties of the sheet, and if the draw ratio is less than 1.05 times, the effect can hardly be expected.

The embossing rolls 14, 14 'and 3
The patterns 4, 34 'are striped patterns in the direction orthogonal to the roll axis. When the pitch of this striped pattern is p and the depth of the pattern is d, the draw ratio X in the transverse direction of the sheet is expressed by the following equation. ^{X = 1 / cos (tan -1} 2d / p) transverse draw ratio than Ru der least 1.05, X ≧ 1.05
Therefore, the following equation is derived by rearranging. d / p> 0.16 In the pattern of the embossing roll of the present invention, it is preferable that the pitch p and the depth d of the pattern are within the range of the above formula. Specifically, the pitch p of the pattern is preferably 0. 1 to 20 mm, more preferably 0.5 to 10 mm, pattern depth d is preferably 0.1 to 10 mm, more preferably 0.5 to 5 mm
It seems to be.

The sheet thus stretched in the transverse direction is
Subsequently, the film is stretched in the longitudinal direction. The stretching treatment method in the longitudinal direction is not particularly limited, and a known stretching treatment method is used, for example, a normal roll stretching method performed by changing the peripheral speed of rolls between two ordinary sets of nip rolls. You can also Also, a pair of embossing rolls in which a pattern is engraved so that the convex part of one roll corresponds to the concave part of the other roll, and the pattern is a pair of embossing patterns that are striped in the horizontal direction with respect to the roll axis. It can also be performed by a stretching method using a roll or the like. In the longitudinal stretching treatment, the sheet can be heated if necessary, and the sheet can be preheated before that.

Further, after the sheet is stretched in the transverse direction in the previous step, the sheet may be cooled once, and then the preheating for the stretching in the longitudinal direction can be reheated, or the stretching heating in the previous step can be preliminarily performed. It can also be used as heating. Generally, after performing such a stretching process and then performing heat treatment under tension,
It is preferable to cool to room temperature below the stretching temperature and then take out.

In the longitudinal stretching treatment, the stretching ratio is preferably 1.2 to 4.0 times, and 1.5 to 3.
It is more preferably 0 times. If the stretching ratio in the stretching treatment in the longitudinal direction exceeds 4.0 times, the mechanical balance and strength are not maintained, and if it is less than 1.2 times, the moisture permeability of the obtained porous sheet becomes low.

The porous sheet which has been subjected to the stretching treatment in the longitudinal direction may be subjected to a surface treatment such as corona discharge treatment, if necessary, and may be provided with an uneven pattern on the surface of the sheet. .

[0045]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

Example 1 Linear low density polyethylene 10
0 parts by weight (Mitsui Petrochemical Industry Co., Ltd., Ultzex 2520F), surface-treated calcium carbonate (Shiraishi Industry Co., Ltd., Ryton 22S) 150 parts by weight and polyester (trimethylolpropane / adipic acid / stearic acid = 2) SV = 240 consisting of mol / 1 mol / 4 mol,
A resin composition consisting of 5 parts by weight of AV = 1, OHV = 8) was mixed by a Henschel mixer, and then kneaded into pellets by a biaxial kneader having a diameter of 45 mm. Then, the kneaded pellets were molded into a sheet having a sheet width of 300 mm by an inflation method using a single screw extruder having a diameter of 32 mm. Using the steel sheet embossing roll having a diameter of 200 mm and having a pattern pitch p of 4 mm and a depth d of 1.4 mm, the formed sheet is roll temperature 60 ° C., roll pressure 100 kg /
The film was stretched 1.22 times in the transverse direction at a cm ² . Then diameter 2
The above sheet was stretched 1.7 times in the machine direction at 50 ° C. using a roll stretching machine having a width of 00 mm and a width of 500 mm to obtain a porous sheet.

Each of the obtained porous sheets was evaluated according to the following evaluation criteria. The results and the thickness of the obtained porous sheet are shown in [Table 1].

Evaluation criteria for porous sheet (1) Water vapor transmission rate: measured in accordance with JIS Z-0209. (2) Tear strength (longitudinal direction); JIS P-8116
Measured according to. (3) Water pressure resistance; measured according to JIS L-1092. (4) Texture: The obtained porous sheet was evaluated according to the following criteria by touch feeling with fingers. ◎: Soft and very good texture. ○: Soft and good texture. Δ: Slightly hard and slightly bad in texture. X: Hard and bad texture.

Example 2 Linear low density polyethylene 10
0 parts by weight (Mitsui Petrochemical Co., Ltd., Ultzex 2520F), polyethylene terephthalate (Unitika Co., Ltd., Elitel MA2100) 60 parts by weight, polystyrene-polyisoprene-polystyrene block copolymer (Shell Japan Co., Ltd.) Manufactured by Califflex) and 10 parts by weight of ethylene-maleic anhydride-acrylic acid ester copolymer (Sumitomo Chemical Co., Ltd., Bondine) are mixed with a Henschel mixer, and then a twin-screw kneader having a diameter of 45 mm. And kneaded into pellets. Styrenic thermoplastic elastomer as a rubber elastic body (Shell Chemical Co.,
Kraton G1657) was used. Then, the kneaded pellets were molded into a sheet having a sheet width of 300 mm by an inflation method using a single screw extruder having a diameter of 32 mm.
Next, the pattern pitch of the above-mentioned sheet is 4 mm.
200 mm diameter steel embossing roll with depth d of 1.4 mm, roll temperature 60 ° C, roll pressure 100 k
The film was stretched 1.22 times in the transverse direction at g / cm ² . Then
Using a roll stretching machine having a diameter of 200 mm and a width of 500 mm, the above sheet was stretched at 50 ° C. in the longitudinal direction by 3.0 times to obtain a porous sheet. The evaluation of the obtained porous sheet was carried out in Example 1.
I went the same way. The results and the thickness of the obtained porous sheet are shown in [Table 1].

[Comparative Example 1] An embossing roll having a pattern pitch p of 1.2 mm and a depth d of 0.13 mm was used as the embossing roll, except that the transverse draw ratio was 1.02. The same operation as in Example 1 was performed to obtain a porous sheet. The obtained porous sheet was evaluated in the same manner as in Example 1. The results and the thickness of the obtained porous sheet are shown in [Table 1].

Comparative Example 2 Using the resin composition of Example 1, the same operation as in Example 1 was carried out to obtain a sheet having a diameter of 200 mm and a width of 500 mm.
It was stretched 2.3 times in the machine direction at 0 ° C. to obtain a porous sheet. The obtained porous sheet was evaluated in the same manner as in Example 1.
The results and the thickness of the obtained porous sheet are shown in [Table 1].

Comparative Example 3 Using the resin composition of Example 2, the same operation as in Example 2 was performed to obtain a sheet having a diameter of 200 mm and a width of 500 mm.
It was stretched 3.0 times in the longitudinal direction at 0 ° C. to obtain a porous sheet. The obtained porous sheet was evaluated in the same manner as in Example 1.
The results and the thickness of the obtained porous sheet are shown in [Table 1].

[0053]

[Table 1]

[0054]

EFFECTS OF THE INVENTION The porous sheet of the present invention has a soft and supple texture, and has a necessary and sufficient strength when used as a moisture-permeable leakproof sheet for absorbent articles such as disposable diapers. . Further, according to the method for producing a porous sheet of the present invention, a porous sheet having a soft and supple texture and having a necessary and sufficient strength when used as a moisture-permeable leak-proof sheet for absorbent articles such as disposable diapers. The flexible sheet can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for stretching in the transverse direction in the method for producing a porous sheet of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a schematic view showing another example of an apparatus for stretching in the transverse direction in the method for producing a porous sheet of the present invention.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

5 is an enlarged view of an essential part of a cross section taken along line VV in FIG.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Haruo Sakahashi Inventor Haruo Sakahashi 2606 Akabane Kai, Haga-gun, Tochigi Kao Corporation Research Institute (56) Reference JP 63-162736 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08J 9/00 B29C 55 / 02,59 / 04

Claims (8)

(57) [Claims] 1. A sheet molded from a melt-kneaded product of a resin composition (a) containing a polyolefin resin and a filler as essential components, so that a convex portion of one roll corresponds to a concave portion of the other roll. a pair of embossing roll pattern is carved, 1.05 laterally by a pair of embossing rolls is a stripe pattern perpendicular direction該模-like with respect to the roll axis
A porous sheet obtained by performing a stretching treatment in the longitudinal direction after a stretching treatment of at least twice . 2. The porous sheet according to claim 1, wherein the blending ratio of the filler in the resin composition (a) is 50 to 400 parts by weight based on 100 parts by weight of the polyolefin resin. 3. A longitudinal porous sheet stretch ratio claim 1 or 2, wherein a 1.2 to 4.0-fold. 4. A sheet molded from a melt-kneaded product of a resin composition (b) containing a polyolefin resin and a thermoplastic resin incompatible with the polyolefin resin as essential components, wherein the convex portion of one roll is the other. Is a pair of embossing rolls in which a pattern is engraved so as to correspond to the recessed portion of the roll, and the pattern is a striped pattern in a direction perpendicular to the roll axis ,
A porous sheet obtained by stretching in a longitudinal direction. 5. The blending ratio of the thermoplastic resin incompatible with the polyolefin resin in the resin composition (b) is 10 to 100 parts by weight of the polyolefin resin.
The porous sheet according to claim 4, which is 100 parts by weight. 6. The porous sheet according to claim 4 or 5, wherein the stretching ratio in the transverse direction by the embossing roll is 1.05 times or more. 7. A longitudinal porous sheet according to any one of claims 4-6 draw ratio is 1.2 to 4.0 times the. 8. A polyolefin resin and a filler are essential components.
And a resin composition (a) or a polyolefin resin
It is necessary to use a thermoplastic resin that is incompatible with the polyolefin resin.
A melt-kneaded product of the resin composition (b) used as the ingredient is formed into a sheet, and the sheet is embossed with a pattern such that the convex portion of one roll corresponds to the concave portion of the other roll. A pair of embossing rolls, each of which is a roll and has a striped pattern in a direction perpendicular to the roll axis, is stretched at least 1.05 times in the transverse direction and then 1.2 to 4.0 in the longitudinal direction. A method for producing a porous sheet, which comprises performing a double stretching treatment.