JPH07179637A - Porous sheet and absorbent article using the same - Google Patents

Abstract

(57) [Summary] [Purpose] A porous sheet that has breathability, moisture permeability, and water resistance, yet has high strength and is industrially safe and can be continuously produced at high speed. And to provide an absorbent article using the same. [Structure] The present invention comprises 55 to 90 parts by weight of a crystalline polyolefin resin having a melt index of 3 g / 10 minutes or less,
It has an ester bond in the molecule and has a volatilization temperature of 24 at normal pressure.
Compounds 45 to 10 having a melting point of 100 ° C or lower and 0 ° C or higher
A sheet formed from a melt-kneaded product containing 1 part by weight, stretched in at least one direction, a liquid-permeable surface material, a leak-proof backing material, and a space between these double-sided materials. In the absorbent article including the absorbent body disposed in the above, the above-mentioned porous sheet is used as the backside 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 and an absorbent article using the same, and more specifically, to a porous sheet having excellent tensile strength and molding productivity and having moisture permeability, water pressure resistance and the like. The present invention relates to a sheet and an absorbent article using the sheet.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
As a method for manufacturing a porous sheet, a method is known in which 40 parts by weight or more of an inorganic filler is melt-kneaded in an olefin resin such as polyethylene or polypropylene to form a sheet, and then stretched in a uniaxial or biaxial direction. There is. The porous sheet thus obtained is excellent in breathability and moisture permeability and does not cause a dew condensation phenomenon, and thus is suitably used for wallpaper, wrapping paper, and the like. Further, by imparting further flexibility to the excellent properties of such a porous sheet, it can be used as a back material of a disposable diaper or the like. In order to impart flexibility to the porous sheet, it has been proposed to use linear low density polyethylene as the olefin resin.

The commonly used disposable diapers are
It consists of an absorbent body that absorbs excrement such as urine, a surface material that covers the surface of the absorbent body and is applied to the skin, and a back surface material that covers the absorbent body and prevents liquid leakage. ing. In addition, it has a stretching function that is provided to prevent wetting from the waist and legs, and a fastening function that consists of tape, etc. that fastens the dorsal and ventral waist when wearing a diaper. I have it. The fastening tape having a width of about 25 mm is often used for convenience. If you try to peel off the fastening tape for diaper wearing mistakes or to check urine while wearing it, the backing material with flexibility will be torn due to insufficient strength,
I have to replace it with a new diaper. In order to prevent this, a wide holding tape (commonly called landing tape) is attached in advance to the back surface material of the ventral waist circumference, and a fastening tape (commonly known as fastening tape) is pasted on it when mounting. The fastening tape can be repeatedly attached and removed.

However, the use of landing tape has the drawback of increasing the number of diaper constituting members and the number of manufacturing processes. Since landing tape is the most expensive diaper material, using a wide range (large amount) of the tape increases the cost. Further, even if the landing tape is wide, the fastening tape may stick to the backing material other than the landing tape depending on the wearer's body shape, and the fastening tape cannot be removed.

As a high-strength porous sheet, Japanese Unexamined Patent Publication No.
In Japanese Patent Publication No. 98057, "a manufacturing method in which a filler, a specific plasticizer, and a radical generator are mixed with a specific polyolefin, inflation molding is performed, and further uniaxially stretched in a take-up direction"
Is proposed. However, such an improved porous sheet has a strength up to slightly less than twice that of a stretched sheet formed from a molded sheet obtained by melt-kneading an ordinary olefin resin with an inorganic filler.
However, landing tapes such as disposable diapers cannot be omitted with this level of strength. Furthermore, when a radical generator is used, the melt flow characteristics of the molded product are different from that of the pre-molding composition, making it difficult to recycle unnecessary parts such as edges that occur in a normal actual production process.
There is a problem of poor productivity.

As another method for producing a porous sheet, Japanese Patent Publication No.
No. 38011, “A specific crystalline polymer and a specific compound (miscible with the polymer) are melt-blended, formed into a sheet, phase-separated in the cooling process, and stretched to form a fine film. A method for producing a porous sheet "has been proposed. Such a microporous sheet can have a strength of 2 to 3 times that of an ordinary olefin resin melt-kneaded with an inorganic filler and stretched. However, this is still not enough to eliminate the landing tape. According to the study by the present inventors, it is necessary that the strength is at least 4 times, preferably 5 times that of the porous sheet produced by the usual manufacturing method.

Further, in the formulation of such a microporous sheet, since the volatilization temperature of the compound used is low, not only is there a risk of environmental pollution and ignition due to smoking during sheet formation,
The volatile matter adheres to the die lip and causes the occurrence of a so-called "eye dent". Therefore, there is a problem that the industrial productivity is remarkably deteriorated due to frequent disassembly and cleaning after interrupting the molding. Therefore, an object of the present invention is to provide a porous sheet which has breathability, moisture permeability, and water resistance, and which has high strength and is industrially safe and can be continuously produced at high speed, and a porous sheet having excellent productivity. An object is to provide an absorbent article using the same.

[0008]

Means for Solving the Problems The inventors of the present invention have made extensive studies in order to solve the above problems, and as a result, have found that a crystalline polyolefin resin having a specific melt index and a compound having a specific volatilization temperature and melting point are used. It has been found that the above object can be achieved by finding that a sheet obtained by melting and kneading a specific amount of is a porous sheet, which has a very high tensile yield strength.

The present invention has been made based on the above findings, and has 55 to 90 parts by weight of a crystalline polyolefin resin having a melt index of 3 g / 10 minutes or less, and has an ester bond in the molecule and volatilization under normal pressure. A porous sheet obtained by stretching a sheet molded from a resin composition containing 45 to 10 parts by weight of a compound having a temperature of 240 ° C. or higher and a melting point of 100 ° C. or lower in at least one direction. To do. The present invention also includes a liquid-permeable surface material,
In an absorbent article consisting of a leak-proof backing material and an absorber arranged between these double-sided materials, as the backing material,
An absorbent article characterized by using the above-mentioned porous sheet.

Hereinafter, the porous sheet according to the present invention and the absorbent article using the same will be described in detail. The porous sheet according to the present invention is a sheet obtained by forming a resin composition into a sheet shape and subjecting it to stretching, and the resin composition comprises a crystalline polyolefin resin and a compound having an ester bond in the molecule, and if necessary. Fillers, colorants, etc. are included.

The crystalline polyolefin resin used in the present invention is mainly composed of polypropylene resin, but other than that, it is a copolymer resin of propylene and ethylene, and other vinyl contained in an amount that does not impair the crystallinity of propylene and ethylene. It may be a copolymer resin with a monomer. The crystalline polyolefin resin has a melt index of 3 g / 10 minutes or less, preferably 0.2 to 3 g / 10 minutes. Among them, the melt index generally used for extrusion molding is 0.2.
A crystalline polypropylene resin having a content of ˜2 g / 10 minutes and a crystalline ethylene-propylene copolymer resin having an ethylene content of 20% by weight or less are preferable. Especially texture and strength (yield point strength)
From the viewpoint of
Most preferred is 15% by weight of crystalline ethylene-propylene copolymer resin. It is also preferable to use a mixture of two or more of the above polymers or copolymers.

The melt index of the above resin is 3 g / 1
When a porous sheet having a length of more than 0 minutes is used, the strength of the porous sheet is lowered, and it becomes difficult to obtain the required strength as a backing material such as a disposable diaper. Further, it is conceivable to increase the thickness of the porous sheet in order to obtain the required strength, but if it is increased, the moisture permeability of the porous sheet decreases and the cost of the product increases. Further, the insufficient tear strength of the porous sheet cannot be expected to have a sufficient effect even if it is thickened.
If the melt index of the above resin is less than 0.2 g / 10 minutes, a problem arises in that a large amount of power is required for extrusion molding during the sheet molding. In the present invention,
The melt index is a value measured according to ASTM D-1238 at 230 ° C. and 2.16 kgf.

The compound having an ester bond in the molecule used in the present invention is a combination of an aliphatic or aromatic monobasic or polybasic carboxylic acid and an aliphatic, alicyclic or aromatic monohydric or polyhydric alcohol, respectively. Or an ester compound (that is, a mono- or polyester) obtained from a dehydration condensation reaction by a combination of compounds having both a hydroxyl group and a carboxyl group in the molecule. Among them, polybasic carboxylic acids are preferable as the aliphatic and aromatic carboxylic acids, and aromatic dicarboxylic acids, tricarboxylic acids and tetracarboxylic acids are particularly preferable as the aromatic polybasic carboxylic acids, and examples thereof include phthalic acid, trimellitic acid and pyromellitic acid. Is mentioned. As the aliphatic carboxylic acid, aliphatic dicarboxylic acid and tricarboxylic acid are preferable. As the alcohol, monohydric alkyl alcohol or the like is preferable. As the compound having an ester bond in the molecule, an ester compound (that is, mono- or polyester) obtained from an aromatic polybasic carboxylic acid and a monovalent alkyl alcohol, or an aliphatic polybasic carboxylic acid and a monovalent alkyl alcohol The resulting ester compound (ie mono or polyester) is preferred. Further, an ester compound (that is, mono- or polyester) of a polyhydric alcohol (particularly a polyhydric alkyl alcohol) and a monocarboxylic acid (particularly an aliphatic monocarboxylic acid) is also preferable. Furthermore, from the viewpoints of preventing environmental pollution and safety, polyesters obtained from an aliphatic dicarboxylic acid or tricarboxylic acid and a monovalent alkyl alcohol are preferable. Among them, an ester compound obtained from a monovalent alkyl alcohol and an aromatic polycarboxylic acid such as phthalic acid, trimellitic acid or pyromellitic acid, or an aliphatic polycarboxylic acid such as adipic acid, sebacic acid or citric acid, and glycerin Obtained from polyhydric alcohols such as diglycerin, trimethylolpropane, pentaerythritol, dipentaerythritol or sorbitan and aliphatic monocarboxylic acids such as capric acid, lauric acid, palmitic acid, stearic acid or oleic acid. Preferred are the ester compounds mentioned. It is also preferable to add a small amount of polycarboxylic acid such as adipic acid to the ester so that the obtained ester compound does not gel. Furthermore, from the viewpoint of environmental pollution prevention and safety, polyester obtained from an aliphatic carboxylic acid and an aliphatic alcohol is preferable. The ester compound can be prepared from one or more of the carboxylic acids and one or more of the alcohols. The preparation method is not particularly limited, and any conventionally known esterification method can be used. Further, the above ester compound is not only an ester in which all of the carboxyl groups in the carboxylic acid and the hydroxyl groups in the alcohol have completely reacted, but also some of the carboxyl groups in the carboxylic acid and / or the hydroxyl groups in the alcohol have not reacted. It may be a partially esterified product left as it is.

The compound having such an ester bond also has a volatilization temperature at atmospheric pressure of 240 ° C. or higher, preferably 25.
It is 0 ° C or higher, and the melting point of the compound is 100 ° C or lower, preferably 80 ° C or lower. The sheet molding temperature of the resin composition of the crystalline polyolefin resin and the compound in the present invention is 180 to 250 ° C, preferably 190 to 24 ° C.
It is 0 ° C. If the volatilization temperature of the compound having an ester bond in the molecule at atmospheric pressure is less than 240 ° C., smoke of the volatile matter is likely to occur during sheet molding. Emission of volatile matter during molding not only poses a risk of environmental pollution and ignition, but also causes volatile matter to adhere to the die lip and cause burns, which is commonly referred to as "eye stain". Therefore, the sheet molding has to be interrupted once and the die lip has to be disassembled and cleaned frequently, and the industrial productivity is remarkably inferior. Therefore, the preferable volatilization temperature of such a compound is 250 ° C. or higher, and the particularly preferable volatilization temperature is 260 ° C. or higher.

Further, the melting point of the compound is limited to 100 ° C. or less. When the molded sheet is stretched, it is easier for the sheet to become finer when the compound is softened or melted at the stretching temperature. This is because it is porous, and a more preferable melting point is 80 ° C. or lower. In addition, "volatilization temperature" used in this specification
Is a thermobalance, in a nitrogen stream (30 ml / min),
The heating rate is 10 ° C./min, the sample is measured at 10 mg, a heating weight loss curve is drawn, and the temperature at which the weight loss is 1% is meant.

Specific preferred compounds satisfying such conditions include distearyl phthalate, trioctyl trimellitate, tetraoctyl pyromellitate, distearyl adipate, distearyl sebate, trimethylolpropane trilaurate, penta Examples thereof include erythritol tetracaprate. These can be selected from the combination of the solubility parameter of the crystalline polymer and within several units.

The crystalline polyolefin resin used in the present invention (hereinafter abbreviated as "resin") has an ester bond in the molecule, has a volatilization temperature of 240 ° C. or higher at normal pressure and a melting point of 100 ° C.
The compounding ratio of the following compounds (hereinafter abbreviated as “compound”) is
"Compound" 45-1 relative to 55-90 parts by weight of "resin"
0 part by weight, preferably 35 to 20 parts by weight of "compound" with respect to 65 to 80 parts by weight of "resin". When the amount of the "compound" is more than 45 parts by weight, the sheet moldability of the resin composition is poor, the strength of the porous sheet obtained by the stretching treatment is insufficient, and the compound bleeds out from the sheet during long-term storage. And lack practicality. Further, if the amount is less than 10 parts by weight, it is impossible to obtain a porous sheet satisfying a sufficient moisture permeability by the stretching treatment.

If necessary, a filler, a colorant and the like can be added to the resin composition having the above blending ratio. Fillers, colorants and the like are not particularly limited, and fillers usually used for rubber or plastic, such as calcium carbonate,
Examples thereof include gypsum, barium sulfate, talc, clay, titanium oxide, metal powder and other inorganic substances or organic metal salts mainly composed of inorganic substances. Further, a granular or powdery material of thermosetting resin such as phenol resin, epoxy resin or sodium polyacrylate can be used. These fillers are 50 μm or less,
It is preferably used as a powder or granular material having an average particle diameter of 0.1 to 5 μm. The colorant may be organic or inorganic. Furthermore, if necessary, a small amount of a usual resin physical property improving agent such as a stabilizer and an antistatic agent may be used so long as the basic physical properties of the porous sheet of the present invention are not adversely affected.
These additives are added in an amount of 0.1 to the total amount of the resin composition.
-30 wt%, preferably 1-20 wt% can be added.

In forming a sheet from a melt-kneaded product of the above resin composition, the melt-kneading is preferably carried out by a kneading method using a commonly used twin-screw kneading extruder. For actual production, "resin" is supplied from the hopper. However, a method in which the “compound” is press-fitted with a metering pump from the kneading part (middle abdomen) of the extruder in which the resin is plasticized is preferable. When the melting point of the "compound" is equal to or higher than room temperature, the "compound" is heated to a temperature equal to or higher than the melting point to be liquid and injected. In the sheet forming following the melt kneading, the molten resin composition is supplied to the die through a gear pump attached to the discharge part (tip) of the twin-screw kneading extruder, or the twin-screw kneading extruder and the single-screw extruder are combined in tandem. The method of feeding the die through a single screw extruder is preferable.

Further, the melt-kneaded material (compound) is once extruded into a filament shape by a twin-screw kneading extruder, cut into pellets, and then the pellets are fed to a single-screw extruder equipped with a die to form a sheet. A molding method is also good. When the melt-kneaded product is formed into pellets, the cooled filament is stretched to about 1.2 to 1.5 times and then cut, rather than being cooled and cut as it is in the usual molten resin composition extruded into a filament shape. Is desirable. If this step is omitted, a part of the "compound" may bleed on the surface of the filament, and the bite into the subsequent single-screw extruder may be deteriorated, resulting in poor sheet formability. The sheet may be formed by either a flat die or a circular die, but a circular die is preferable from the viewpoint of sheet yield.

Further, in order to obtain the porous sheet of the present invention with a good yield, the cooling conditions in the sheet molding of the resin composition are important. That is, crystal formation (crystal size) of the crystalline polyolefin resin by cooling the molten resin composition is important. For example, formation of a maximum crystal by remarkable slow cooling,
Also, the formation of fine crystals due to remarkable quenching hinders uniform stretching in the subsequent stretching process, resulting in the resulting porous sheet having low strength and low moisture permeability. Preferable cooling conditions are such that the resin composition temperature is 0.1 to 3 from the die discharge temperature to the melting temperature of the crystalline polyolefin resin.
sec, the time to further drop 100 ° C from the melting temperature is 2 to 2
It is 0 sec. For example, in the case of a resin composition using polypropylene having a melting point of 175 ° C., the melt-kneading temperature is 220 to
240 ° C., the melting temperature is 158-160 ° C.,
The former time is 0.8-2.0 sec, the latter time is 5-
20 seconds.

The function of the nucleating agent (crystal nucleating agent) is also important. The crystalline polyolefin resin that is already on the market contains a high-rigidity, high-cycle grade nucleating agent, and a substance that has a substantially nucleating function even if it is not blended as a nucleating agent. There are also things. It is preferable to add a nucleating agent to the grades in which these are not added and the grades in which the effect of the nucleating agent is inferior are inferior, if necessary. The nucleating agent used is not particularly limited, and nucleating agents well known in the art may be used. For example,
Plastics (published by the Industrial Research Council) Vol. 43, N
o. "Functions and effects of plastic compounding agents = nucleating agents" are introduced on pages 11, 113 to 116. Specific examples thereof include metal salts of aromatic carboxylic acids (Al-PTBBA, etc.), sorbitol derivatives, organic phosphates (PTBNa, etc.), high melting point polymer nucleating agents, talc as an inorganic nucleating agent, and the like.

The sheet material of the resin composition in the porous sheet according to the present invention is stretched by uniaxially stretching in the machine direction (MD), or after uniaxially stretching, a tenter stretching machine, an air inflation stretching machine or a mandrel stretching. It can be obtained by sequentially biaxially stretching in the transverse direction (TD) by a machine or by simultaneously biaxially stretching in the longitudinal and transverse directions.
In this case, the stretching temperature is preferably a temperature that is 10 ° C. or more lower than the melting point of the resin composition at room temperature or higher, and particularly 30 ° C. or more lower than the melting point. The stretching ratio is at least 1.1 times in the uniaxial direction (the length after stretching is 1.1 with respect to the original length of 1.0) or more, preferably 1.3 times or more and 6 times or less, that is, in the case of uniaxial stretching. Is preferably 1.1 to 6 times in the machine direction, and in the case of biaxial stretching, it is 1.1 to 6 times in the machine direction and the transverse direction, respectively, in order to maintain mechanical balance and strength, and to exhibit excellent moisture permeability and water pressure resistance. .

The porous sheet according to the present invention has a moisture permeability
Is 0.5-4.0g / 100cm²・ Hr, especially 0.8
~ 2.5g / 100cm²・ I want to be Hr
Yes. Water vapor transmission rate is 0.5g / 100cm²・ Lower than Hr
And the effect of preventing stuffiness as a backing material for absorbent articles is poor.
And vice versa, 4.0g / 100cm²・ Exceeds Hr
Then, the water pressure resistance decreases, and the leakproof property decreases. Porous sheet
When using for absorbent articles such as disposable diapers,
The water pressure resistance of the sheet is 1.5 mAq or more, particularly preferably
Needs to be 2.0 mAq or more. Book again
The porous sheet according to the invention has a tensile yield strength of 11
0 kgf / cm ²The above is preferable, and particularly preferable
120kgf / cm²Or more, more preferably 13
0 kgf / cm²That is all.

Next, the absorbent article according to the present invention will be described in detail. The absorbent article of the present invention includes a disposable diaper,
There are incontinence briefs and sanitary napkins and the like, for example, disposable diapers include an absorber that absorbs excrement such as urine, a surface material that covers the surface of the absorber and is applied to the skin, and a liquid leak that covers the absorber. It consists of a backing material to prevent them, and these are bonded and integrated. In addition, a stretchable function to prevent wetting from the waist and legs, and a fastening tape that secures the back waist and the abdominal waist when wearing a diaper. It has a function. The fastening tape having a width of about 25 mm is often used for convenience.

The above-mentioned porous sheet according to the present invention is used as the backing material. The thickness of the backing material used for disposable diapers is usually 25 μm or more, preferably 35 μm or more, from the flexibility required for diapers, the waist of the sheet required when assembling and processing the diaper, and the security of using the backing material. On the other hand, it is 55 because of the flexibility and cost required for diapers.
It is not more than μm, preferably not more than 45 μm.

In the disposable diaper thus constructed, the strength of the backing material required for directly removing the fastening tape from the backing material without using the so-called landing tape is the tensile yield point strength per sheet width of 1 cm. 600 gf or more, preferably 700 gf or more, particularly preferably 800 gf or more. Therefore, the thickness is 55μ
To obtain 600 gf / cm in m, 109 kgf /
The backing material must have a strength of at least cm ² . in this way,
The backside material of the disposable diaper has a sufficient strength when the tensile yield point strength is 110 kgf / cm ² or more as described above. Therefore, since it is not necessary to use the landing tape, a diaper is not attached incorrectly, and the backing material is not broken even if the diaper is peeled off for urine inspection while wearing. Further, if the moisture permeability of the back surface material is within the above range, stuffiness does not occur and a comfortable wearing feeling can be maintained.

[0028]

[Examples 1 to 5 and Comparative Examples 1 to 2 (porous sheet)]

-Composition of "resin" and "compound": density of "resin" of 0.91 g / cm ³ , melt index of 0.4 g / 1
270 cm of crystalline polypropylene (Chisso Petrochemical, Chisso HCPPXF1932) having a melting point of 169 ° C. for 0 minutes
^The mixture was supplied at a rate of ³ / min, and the following various samples of "compound" were supplied to the twin-screw kneading extruder described below such that "resin": "compound" = 70:30 (weight ratio).

Various samples of “compound”: “compound” of Example 1 = esterified product of phthalic acid and stearyl alcohol (acid value = 0.1, OH value = 0.2: abbreviation DSP) Compound ”= esterification product of phthalic acid and isotridecyl alcohol (Vinizer # 2 manufactured by Kao Corporation)
0: Abbreviation DTDP) "Compound" of Example 3 = Esterification product of trimellitic acid and 2-ethylhexyl alcohol (Trimex T-08 manufactured by Kao Corporation: Abbreviation TOT) "Compound" of Example 4 = pyromellitic acid And an esterified product of 2-ethylhexyl alcohol (Piromex P-08 manufactured by Kao Corporation: abbreviated TOP) “Compound” of Example 5 = esterified product of adipic acid and stearyl alcohol (acid value = 0.2, OH value = 0) .2:
Abbreviation DSA "Compound" in Comparative Example 1 = Mineral oil (Chuo Kasei Co., Ltd., Flow Para 350S, flash point 220 ° C, aniline point 112 ° C, aroma / naphthene / paraffin type = 0/34/66: Abbreviation 350S ) "Compound" of Comparative Example 2 = esterified product of phthalic acid and 2-ethylhexyl alcohol (Vinizer # manufactured by Kao Corporation)
80: Abbreviation DOP) In addition, Table 1 shows the physical properties of the "compound".

[0030]

[Table 1]

Sheet forming: Biaxial kneading extruder (φ45m
m, L / D = 33.5), a circular die (φ200 mm) was connected to the tip (discharge port) of the gear pump. Then, an air-cooled inflation molding facility having a distance of 4 m from the die to the nip roll was used. The "resin" was supplied from the hopper, and the heated and liquefied "compound" was injected by a gear pump into the middle (kneading) part of the twin-screw kneading extruder. The set temperature is 190 ° C for the cylinder C1 part (hopper side) of the extruder, 210 ° C for C2 part, and 2 for C3 to C8 part.
40 degreeC, the gear pump part was 230 degreeC, and the die was 230 degreeC. A sheet having a thickness of 40 μm was obtained at a sheet folding width of 60 cm and a take-up speed of 8 m / min while blowing air at 20 ° C. from an air ring onto the bubble to forcibly cool it.

Stretching treatment: Using a roll stretching machine with a width of 1 m, the above sheet was stretched 1.6 times in the molding direction at 60 ° C., and subsequently annealed 1.5 times (1.5 times before stretching).
Times). The obtained sheets were all 36 to 38 μm.

Evaluation Criteria for Porous Sheet (1) Smoke emission during molding: The smoke emission state of the volatile matter during the sheet molding was visually evaluated according to the following criteria. ⊚: No smoke was emitted. ○: A little smoking. Δ: A lot of smoke is emitted. X: Very much smoke is emitted. (2) Occurrence time (accumulation) of eye blemishes: The time until occurrence of a die line, which can be visually observed on the sheet surface in the above-mentioned sheet molding, was measured. (3) Sheet formability: The sheet was visually evaluated according to the following criteria. ◎: Valve stable, no die line. ○: Valve is stable and has a die line. Δ: Valve fluctuation. X: Cannot be molded. (4) Stretchability; ⊚: No cutting, uniform whitening *. * Confirmed that whitening and stretching are correlated. ◯: No cutting, slight whitening unevenness. Δ: No cutting, many whitening unevenness. X: Cutting. (5) Tensile strength at yield point: 10 mm in the direction perpendicular to the stretching direction
Width sheet is 300 mm / min with Tensilon tensile tester
Measured at. (6) Water vapor transmission rate; measured in accordance with JIS Z0208. (7) Water pressure resistance; measured according to JIS L1093B method Table 2 shows the evaluation of the porous sheets of Examples 1 to 5 and Comparative Examples 1 and 2.

Comparative Example 3 A density of 0.90 g / cm ³ and a melt index of 0.5 g were used in place of the “resin” of the example.
/ 10 minutes, a crystalline polypropylene having a melting point of 170 ° C. (Chisso Petrochemical Co., Ltd., Chisso PP FM101) was used, the same DOP as in “Comparative Example 2” was used as the “Compound”, and the sheet manufacturing method and evaluation method were those of the Example. I went the same as 1. Table 2 shows the evaluation for obtaining the porous sheet and the evaluation results of the obtained sheet.

[0035]

[Table 2]

The porous sheet of the present invention is free from volatilization and smoke generation during sheet formation, and therefore has a very long time for generation of eye blemishes and is excellent in productivity, and is flexible and has high strength and is excellent in moisture permeability and leakproofness. Further, the disposable diaper having such a porous sheet as a backing material can be attached and removed with the fastening tape without using the landing tape, and has a simple structure and is excellent in convenience.

[Examples 6 and 7 and Comparative Examples 4 and 5 (Porous Sheet)] In Example 6 and Comparative Example 4, a density of 0.91 g / cm ³ and a melt index were used instead of the “resin” of Example 1. An esterification product of lauric acid and trimethylolpropane (each compound) was used as a "compound" using a crystalline block copolymerized polypropylene (manufactured by Chisso Petrochemical Co., Ltd.) containing 0.5 g / 10 minutes, a melting point of 168 ° C. and 8% by weight of ethylene. Acid value = 0.24, OH value = 3.8: Abbreviation TTL and mineral oil (Idemitsu Kosan Co., Ltd. Diana Process Oil PW-90,
Flash point 272 ° C, aniline point 127.7 ° C, aroma /
Naphthenes / paraffins = 0/29/71: Abbreviation PW
-90) was used. In Example 7 and Comparative Example 5, Example 1 was used.
"Resin" of "," and "compound" respectively TTL and P
W-90 was used. Table 3 shows the physical properties of TTL and PW-90.
Shown in. The sheet manufacturing method and evaluation method were the same as in Example 1,
Further evaluation (8) was performed. The evaluation for obtaining the porous sheet and the evaluation of the obtained sheet are shown in Table 4. Evaluation (8) Texture ◎: Flexible and very good texture ○: Flexible and good texture Δ: Slightly hard and slightly poor texture ×: Hard and poorly texture

[0038]

[Table 3]

[0039]

[Table 4]

[Examples 8 to 9 and Comparative Examples 6 to 7 (disposable diapers)] Porous sheets of Example 1, Example 6 and Comparative Example 1, and conventional linear low density polyethylene and calcium carbonate Using the sheet as a backing material, a disposable diaper including a front surface material, an absorber, a back surface material and a fastening tape (however, no landing tape was used) was manufactured (in order, Example 8, Example 9, Comparative Example 6 and Comparative Example 7). As a result, in Examples 8 and 9, as compared with the sheet of Comparative Example 1 and the diapers using the conventional backing material (Comparative Examples 6 and 7), the fastening tape was attached and removed well. In particular, the diaper of Comparative Example 7 was not peeled at all and the backing material was broken. In terms of texture, the diaper of Example 9 was soft and had the best feel.

[0041]

INDUSTRIAL APPLICABILITY The porous sheet of the present invention has breathability, moisture permeability, and water resistance, and is excellent in high strength and industrially safe and high-speed continuous production. ing. Further, the absorbent article of the present invention can be attached / detached with the fastening tape without using a landing tape, which is excellent in convenience and economically advantageous.

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Claims (6)

[Claims] 1. A crystalline polyolefin resin having a melt index of 3 g / 10 minutes or less and 55 to 90 parts by weight of a crystalline polyolefin resin, and having an ester bond in the molecule, a volatilization temperature at atmospheric pressure of 240 ° C. or higher and a melting point of 100 ° C. or lower. A porous sheet, which is formed by stretching a sheet molded from a resin composition containing 45 to 10 parts by weight of the compound described above in at least one direction. 2. The porous sheet according to claim 1, wherein the crystalline polyolefin resin is a polypropylene resin or a copolymer resin of propylene and ethylene. 3. The compound is an ester of an alkyl alcohol with at least one or more polybasic carboxylic acid selected from the group of phthalic acid, trimellitic acid, pyromellitic acid and aliphatic polybasic carboxylic acid. The porous sheet according to claim 1 or 2, which is characterized. 4. The compound according to claim 1, which is an ester of a monocarboxylic acid and a polyhydric alcohol.
Alternatively, the porous sheet according to item 2. 5. A moisture vapor transmission rate of 0.5 to 4.0 g / 100 cm.
^2. The porous sheet according to claim 1, wherein the porous sheet is ² · Hr. 6. An absorbent article comprising a liquid-permeable front material, a leak-proof backing material, and an absorber arranged between these double-sided materials, wherein the backing material is any one of claims 1 to 5. An absorbent article using the porous sheet according to any one of 1.