JP2008080747A - Air-permeable water-resistant sheet and absorbent article using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet member which can be used for a hygienic material such as a diaper or the like and a medical material by enhancing the liquid leakage preventive property of a composite sheet material comprising micro-fibrous cellulose and a non-woven fabric. <P>SOLUTION: An air-permeable water-resistant sheet is formed by making a water repellent material 2 overlie a composite sheet material 1 comprising the non-woven fabric and the micro-fibrous cellulose. The water-repellent material is the air-permeable water-resistant sheet containing an olefinic water-repellent agent, a synthetic resin-based binder and a cross-linking agent, and preferably, the non-woven fabric is spun-melt non-woven fabric, the synthetic resin based binder is a styrene-butadiene resin, and the cross-linking agent is ammonium zirconium carbonate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a breathable water-resistant sheet obtained by laminating a water-repellent material on a composite sheet material composed of fine fibrous cellulose and a nonwoven fabric mainly used for hygiene or medical products. The present invention also relates to an absorbent article using this breathable water-resistant sheet.

A sheet-like or film-like material used for hygiene or medical products requires a certain degree of air permeability while not leaking liquid. Although it is difficult for a plastic film to infiltrate a liquid, the plastic film does not have air permeability because the tissue is dense. That is, phase separation by mixing a hydrophobic film such as polyethylene with a filler such as calcium carbonate and a heterogeneous polymer as a sheet material such as a back sheet (non-contact side with a human body) of a diaper that requires water resistance and breathability Although a microporous film by means such as forming a layer is used, it cannot be said that the air permeability (JIS P 8117) of about 100 to 500 S / 100 ml exhibits practically sufficient ventilation performance. Currently. Moreover, although non-woven fabric and paper have air permeability, it is impossible to completely prevent liquid leakage. As a sheet material that solves the drawbacks of these sheet materials, a sheet material composed of microfibrous cellulose and a nonwoven fabric has been proposed (see, for example, Patent Document 1). The fine fibrous cellulose used therein is an extremely thin fibrous cellulose having an average fiber length of 0.3 mm or less and a water retention of 15 mL / g or more, and a slurry of pulp or cotton fibers is obtained by mechanical treatment. There are known what is called bacterial cellulose that is obtained by microfibrosis and what is produced by bacteria. Examples of the mechanical treatment method include a method using a high-pressure homogenizer, a grinder, a refiner, and the like. A thin layer is formed by applying a dispersion obtained by dispersing the fine fibrous cellulose in a solvent on a nonwoven fabric, and the sheet material is prepared by removing the solvent from the thin layer.
JP-A-10-248872

  Since the sheet material is thin, it has good ventilation, and has dust resistance and bacterial barrier properties, so it is an excellent material for hygiene or medical use. However, it has not been put to practical use as an absorbent body for women's goods, diapers for children and adults, because the leakage prevention property of liquids such as urine is insufficient. An object of the present invention is to provide an improved sheet leakage preventing property of a composite sheet material composed of fine fibrous cellulose and a nonwoven fabric, and to provide a sheet material that can be used for sanitary materials such as diapers and medical materials.

  In response to the problem of increasing the water leakage of a composite sheet material composed of fine fibrous cellulose and a nonwoven fabric, the present inventor has selected an olefinic water repellent from among many material systems considered to satisfy the function of water repellency. It has been found that a water-repellent material containing a synthetic resin binder is effective, and that a long-term water leakage is greatly improved by adding a crosslinking agent, particularly a zirconium-based crosslinking agent. It is a thing.

  That is, the present invention is a breathable water-resistant sheet in which a water-repellent material is laminated on a composite sheet material composed of a nonwoven fabric and fine fibrous cellulose, and the water-repellent material is an olefin-based water repellent, a synthetic resin-based binder, and a crosslinking agent. It is a breathable water-resistant sheet characterized by including (Claim 1). The nonwoven fabric is preferably a spun melt nonwoven fabric (Claim 2), and the fine fibrous cellulose has an average fiber length of 0.3 mm or less and a water retention of 15 mL / g or more. Preferred (claim 3).

  The synthetic resin binder is preferably a styrene butadiene resin (Claim 4), and the crosslinking agent is preferably made of ammonium zirconium carbonate (Claim 5). Furthermore, it is preferable that the breathable water-resistant sheet of the present invention is densified by calendering (Claim 6). In addition, the present invention is characterized in that the breathable water-resistant sheet is used for a back sheet portion of an absorbent article (Claim 7).

  In the present invention, in addition to being able to improve the water leakage resistance of a composite sheet material composed of a nonwoven fabric and fine fibrous cellulose by the film-forming effect of a synthetic resin binder containing an olefinic water repellent, zirconium carbonate By adding a system cross-linking agent, it was possible to further improve long-term water leakage resistance. Furthermore, as a result of densifying the whole sheet, the sheet was calendered, and as a result, the density increased and a further improvement in water resistance was confirmed. Moreover, as an effect by a calendar process, the air permeable water-resistant sheet compensates for the defect that it is bulky compared with a microporous film, and the improvement of the printing suitability by smoothness improvement is mentioned. According to an infant wearing test using a diaper in which the back sheet portion of a commercially available diaper is replaced with this breathable water-resistant sheet, the water-proof and breathable properties of the breathable water-resistant sheet of the present invention are practically sufficient. Proven.

  As shown in FIG. 1, the breathable water-resistant sheet of the present invention is a sheet in which a water repellent material 2 is laminated on a composite sheet material 1 composed of a nonwoven fabric and fine fibrous cellulose. In addition, as shown in FIG. 2, the breathable water-resistant sheet of the present invention may have a water repellent material 2 laminated on both surfaces of a composite sheet material 1 made of a nonwoven fabric and fine fibrous cellulose.

  Examples of the nonwoven fabric used in the present invention include nonwoven fabrics obtained from various materials such as natural fibers such as wool and cotton, chemical fibers such as rayon and acetate, synthetic fibers, and inorganic fibers such as glass fibers and carbon fibers. In particular, in the present invention, a nonwoven fabric made of synthetic fibers such as polyethylene, polypropylene, polyester, polyester / polyethylene composite fiber, and polyester / low-melting polyester composite fiber is preferable. Of these, a non-woven fabric made of spunbond (hereinafter referred to as “S”) obtained from polypropylene fibers which are hydrophobic and relatively inexpensive, and a non-woven fabric made of melt blown (hereinafter referred to as “M”) obtained from polypropylene fibers are preferred. Further, in the present invention, a so-called spunmelt nonwoven fabric in which S and M are combined is preferable, and SMS or SMMS is particularly suitable for the purpose of the present invention because it has a low basis weight and is dense. S and M have different fiber diameters and properties due to different manufacturing methods. For example, melt blown non-woven fabric (M) is made of ultrafine fibers of about 0.5 to 5 microns and can remove bacteria and small dust in the air. It is necessary to cover and reinforce with a non-woven fabric. SMS has a three-layer structure in which a melt-blown nonwoven fabric (M) having a low strength is sandwiched between spunbond nonwoven fabrics (S) having a fineness of 10 to 50 microns and a higher strength. SMMS is a non-woven fabric having a four-layer structure in which a melt blow layer is provided as an intermediate layer in order to make the sheet more dense.

Examples of the fine fibrous cellulose used in the present invention include those obtained by mechanically micropulverizing a pulp or cotton fiber slurry, or those called bacterial cellulose produced by bacteria (acetic bacteria). be able to. The fine fibrous cellulose is preferably an extremely thin fibrous cellulose having an average fiber length of 0.3 mm or less and a water retention of 15 mL / g or more. When the average fiber length of fine fibrous cellulose exceeds 0.3 mm or when the water retention is less than 15 mL / g, the penetration into the nonwoven fabric becomes difficult and the anchoring effect is lost, and the adhesion between the fine fibrous cellulose and the nonwoven fabric There is a possibility that problems such as lowering of the thickness and difficulty in forming a uniform texture in the fine fibrous cellulose layer may occur.
The water retention was measured by the following method. 50 mL of an aqueous dispersion of fine fibrous cellulose (0.5 g) was weighed into a centrifugeable test tube (inner diameter 30 mm × length 100 mm, volume 50 mL), and centrifuged at 2000 × g (3300 rpm) for 10 minutes. Then, the amount of sedimentation (mL) was read, and the water retention was calculated according to the following formula.
Water retention (mL / g) = volume of sedimentation (mL) / amount of fine fibrous cellulose (g)

The basis weight of the nonwoven fabric used in the present invention is preferably 10 to 50 g / m ^2, more preferably 12.0 to 20 g / m ² . When the basis weight is less than 10 g / m ² , the strength is insufficient, and when used in an absorbent article such as a diaper, the water resistance is lowered and urine tends to leak, which is not preferable. On the other hand, when the basis weight is more than 50 g / m ² , the sheet is thick and the rigidity is increased, and the cost is further increased. Further, the basis weight of the fine fibrous cellulose is preferably 2.0 to 20.0 g / m ^2, more preferably 4.0 to 10.0 g / m ² . When the weight per unit area is less than 2.0 g / m ² , the water resistance is lowered when used for absorbent articles such as diapers and urine is likely to leak, which is not preferable. On the other hand, when the basis weight is more than 20.0 g / m ² , the air permeability is lowered and the cost is not preferable.

In addition, as a method for producing a composite sheet material constituting the present invention, first, a dispersion liquid in which fine fibrous cellulose is dispersed in water or a mixed solvent composed of water and an organic solvent compatible with water. Is coated on a non-woven fabric to form a composite sheet material. When an organic solvent is mixed and used, methanol, ethanol or the like is used.
The concentration of the dispersion during coating is preferably in the range of 0.5 to 2.0% by weight. In this case, in order to eliminate the influence of air in the nonwoven fabric, the nonwoven fabric used as the base material includes water or a mixed solvent containing water, and a uniform sheet can be produced by leaving it in a deaerated state. . Then, it can manufacture by removing the said solvent contained in this from this sheet | seat, and drying.

  The water repellent material constituting the present invention includes an olefin water repellent, a synthetic resin binder, and a crosslinking agent. As the water repellent, olefin (wax) type, acrylic type, fluorine type, silicone type, etc. are known, but the fluorine type and silicone type are not superior to the olefin type in terms of performance, although they are expensive. Since an acrylic type tends to inhibit air permeability, it is necessary to use an olefin type water repellent in the present invention. The olefin-based water repellent is also called a wax-based water repellent, and is a water repellent mainly composed of natural wax, synthetic wax, fatty acid derivative, etc., and generally has a solid content concentration of 30 to 50 wt. % Emulsion form.

  Examples of the synthetic resin binder include styrene butadiene resin, acrylic resin, polyester resin, and ethylene-vinyl acetate copolymer. Among these, a styrene butadiene resin (SBR) is particularly preferable in terms of a combination of water resistance improvement by film formation and an olefinic water repellent.

  Examples of the crosslinking agent include polyamide epichlorohydrin resin, polyamine epichlorohydrin resin, melamine resin, urea resin, ketone resin, glyoxal, and ammonium zirconium carbonate. In particular, the carboxyl group / hydroxyl group in ammonium zirconium carbonate reacts directly with the functional group in the synthetic resin binder and the olefin water repellent to crosslink, thereby obtaining a water resistance and a sustained effect of the water repellent. It is preferable because a long-term water leakage prevention effect can be obtained.

  The relative ratio of the olefinic water repellent which is a component of the water repellent material used in the present invention and the synthetic resin binder is preferably in the range of 40/60 to 70/30, more preferably from 45/55. The range is 60/40. Further, the amount of the crosslinking agent (particularly zirconium-based crosslinking agent) added thereto is in the range of 4 to 2 parts by weight with respect to 100 parts by weight of the total amount of the olefin-based water repellent and the synthetic resin-based binder. If the amount is more than 4 parts by weight, the pot life of the paint is shortened. If the amount is less than 2 parts by weight, sufficient effects cannot be obtained with water resistance and water repellency.

  Next, the process for producing the breathable water-resistant sheet of the present invention will be described. FIG. 3 is a flowchart of a production method for producing a breathable water-resistant sheet of the present invention by producing a composite sheet material comprising a nonwoven fabric and fine fibrous cellulose using a nonwoven fabric as a base material. The raw material of the nonwoven fabric is fed from the unreel to the production line (substrate unwinding). The substrate is filled and saturated with water and an organic solvent for the purpose of degassing the air in the substrate (pretreatment of the substrate). Thereafter, a slurry of fine fibrous cellulose prepared in advance is coated on the substrate (slurry coating on the substrate), and water and the organic solvent are removed by a vacuum device (vacuum removal). Next, the non-woven fabric / fine fibrous cellulose that has been evacuated to vacuum is dried and fixed (dried and fixed) after being squeezed and drained (pressed by pressing) through a felt press, or dried as it is. The composite sheet material which consists of a nonwoven fabric and a fine fibrous cellulose is manufactured.

  FIG. 4 shows a schematic diagram of an apparatus for producing a composite sheet material with the above steps. The substrate (nonwoven fabric) 800 unwound from the unwinding device 824 is disposed on a net conveyor 810 that is conveyed by a roller 822. A filling saturant (used for the purpose of degassing the air in the base material) 804 is synchronized with the movement of the moving base material 800, and the surface of the base material 800 at the constriction 806 of the filling saturant supplier 814. Supplied on top. The coating slurry 802 is supplied from the head box 812 onto the surface of the substrate 800 so as to be synchronized with the movement of the moving substrate 800. Thereafter, the base material 800 passes between the coating roller 820 and the net conveyor 810 while moving, and is drained by a draining device 850 connected to a vacuum pump (not shown) or the like. A composite sheet material made of fine fibrous cellulose can be obtained.

  Next, as shown in FIG. 3, a water repellent paint prepared in advance is applied to the composite sheet material (water repellent material application) to be laminated, and after drying (fixed to dryness), a calendar process (calendar process) is performed. As a result, the breathable water-resistant sheet of the present invention is produced. In this invention, in order to improve water resistance after a calendar process, it may heat-process and may wind up as needed. In FIG. 3, the manufacturing process of the composite sheet material and the lamination process of the water repellent material are continuous processes, but the breathable water-resistant sheet may be manufactured by separating each process.

  Next, a method for laminating a water repellent material on the composite sheet material composed of a nonwoven fabric and fine fibrous cellulose in the above production process will be described in detail. First, a coating material that becomes a water repellent material is prepared in the following manner. That is, an olefin-based water repellent and a synthetic resin-based binder are mixed with stirring in the following composition to create a main agent, and then a crosslinking agent is added with stirring in the following composition immediately before coating on the composite sheet material. Water is added to prepare a paint having a predetermined concentration and viscosity.

Examples of the water repellent coating method include air knives, Mayer bars, gravure, offset gravure, micro gravure, flexo, reverse roll, blade, curtain, and die, but any coating amount can be obtained. A coating method is also acceptable. Is preferably in the range of 1.0 to 10.0 g / ^{m 2} for coating weight, but more preferably in the range of 1.5~3.0g / ^{m 2.} If it is less than 1.0 g / m ² , sufficient performance may not be obtained due to water resistance and water repellency. If it exceeds 10.0 g / m ² , the water resistance performance is almost saturated, and the cost is low. This is because it becomes higher.
Although the composite sheet material of the present invention has a nonwoven fabric surface and a fine fibrous cellulose surface, it is effective to apply the water repellent material to the highly fibrous fine fibrous cellulose surface, Of course, you may go to both sides.

Next, the absorbent article of the present invention will be described in detail.
The present invention is an absorbent article using the breathable water-resistant sheet as a back sheet.
Examples of the absorbent article include disposable paper diapers and feminine hygiene products, and the back sheet is a sheet provided on the non-contact surface side with the human body as shown in FIG.
A disposable paper diaper will be described as an example of the absorbent article.
FIG. 5 is a plan view of the disposable paper diaper in the present embodiment. 6 is a cross-sectional view taken along the line AB in FIG.

  As shown in FIGS. 5 and 6, the disposable paper diaper (hereinafter referred to as a paper diaper) includes a paper diaper body 30, a fastening part 40 for attaching the paper diaper body 30 to a human body, and a fastening part 40. And an adherend part 50 for causing the above.

  The paper diaper main body 30 includes a top sheet 31 made of a liquid-permeable nonwoven fabric or the like provided on the contact surface side with the human body, a back sheet 32 provided on the outside side when worn, and between the top sheet 31 and the back sheet 32. Gather sheets 34 and 34 provided along the longitudinal direction of the paper diaper main body 30 on both sides of the absorbent body 33 and the absorbent body 33 on the top sheet 31 side, and a paper diaper main body than the gather sheets 34 and 34 It is mainly comprised by the protrusion parts 35 and 35 with which it is provided along the longitudinal direction of the paper diaper main body 30 on the absorber 33 inside 30 width directions.

  As the absorber 33, fluff pulp obtained by pulverizing wood pulp having liquid retention can be used, and a combination of this and a superabsorbent polymer is preferable. In particular, a heat-treated mixture of thermoplastic resin, fluff pulp and superabsorbent polymer is preferable. The superabsorbent polymer may be used by mixing with fluff pulp, or may be partially present in the fluff pulp. The highly water-absorbing polymer is preferably in the form of particles having a holding performance capable of absorbing and holding a liquid 20 times or more of its own weight and having a property of gelling. Examples of such superabsorbent polymers include starch-based, cellulose-based, and synthetic polymers. Particularly, starch-acrylic acid (salt) graft copolymer, saponified starch-acrylonitrile copolymer, sodium carboxymethylcellulose, and the like. Preferred examples include cross-linked products and acrylic acid (salt) polymers.

In the present invention, in the absorbent article (paper diaper) as described above, the breathable water-resistant sheet is used as the back sheet 32 provided on the outside side without being in contact with the human body.
By using the breathable water-resistant sheet of the present invention as the back sheet of such an absorbent article, the breathable water-resistant sheet of the present invention has sufficient breathability, so that the occurrence of skin irritation or rash on the human body is extremely small, and sufficient water resistance is achieved. Therefore, an absorbent article in which moisture such as urine does not leak can be obtained.
Next, the breathable water-resistant sheet and the absorbent article of the present invention will be described in more detail using examples and comparative examples.

Fine fibrous cellulose was prepared as follows.
First, hardwood bleached kraft pulp (trade name: Peace River LBKP manufactured by Daishowa Marubeni International Co., Ltd.) was disaggregated with a pulper at a concentration of 5% by weight for 20 minutes and transferred to a circulation tank to a concentration of 3.5% by weight. Prepared. A fine fibrous cellulose was prepared by beating a 3.5% by weight pulp slurry with a double disc refiner (hereinafter referred to as DDR) under the following conditions. The conditions were as follows. A load was applied as much as possible without causing metal touch (contact between the fixed blade and the rotating blade).
DDR model: AW14 manufactured by Aikawa Iron Works
Disc plate: Blade width 2.0mm, groove width 3.0mm
Pulp flow rate to DDR: 1 m ² / min Average number of passes of DDR: 100 times Blade clearance: range from 0.23 mm to 0.13 mm

The characteristics of the prepared fine fibrous cellulose were as follows.
Water retention: 27 mL / g
Average fiber length: 0.15mm
Viscosity of 0.5 wt% slurry: 320 mPa.s s
Final concentration: 3.0% by weight (because it is diluted with sealing water)

<Preparation of fine fibrous cellulose slurry>
Ethanol was added to the fine fibrous cellulose to give ethanol / water = 65/35 (weight ratio) and a fine fibrous cellulose concentration of 0.7% by weight to prepare a fine fibrous cellulose slurry.

<Nonwoven fabric>
An SMS non-woven fabric made of polypropylene (AVGOL) having the following characteristics was used.
Weight per unit area: 15 g / m ²
Configuration of SMS: Spunbond (1) (5.0 g / m ² )
Melt blown (5.0 g / m ² )
Spunbond (2) (5.0 g / m ² )
Water resistance: 150mmH ₂ O

<Coating of fine fibrous cellulose slurry on non-woven fabric>
The nonwoven fabric (width 1,500 mm, length 10,000 m) was placed in an unwinding device 824 shown in FIG. The non-woven fabric is supplied on a net conveyor 810 set via a roller 822. Preliminary treatment was carried out to saturate the nonwoven fabric with water by supplying water from the filling saturant supply machine 814 at a rate of 17 kg / min onto the nonwoven fabric running on the net conveyor 810 at 40 m / min. The filling saturation agent made of water supplied in this way is applied at the narrowed portion 806 of the coater header as the nonwoven fabric travels. In addition, the clearance between the coating roller 820 and the net conveyor 810 was set to 750 μm by a height adjusting device. On the other hand, the coating slurry 802 is supplied from the storage tank so that the liquid level of the head box 812 is 60 mm. After the above preliminary treatment was completed, the supplied coating slurry 802 was supplied to the above-mentioned nonwoven fabric at a rate of 42 kg / min. Thereby, the fine fibrous cellulose layer was formed on the nonwoven fabric.

Next, this was supplied to the upper part of the liquid removal apparatus 850, liquid was drained with a vacuum of -30 kPa, and it dried with the cylinder dryer at the temperature of 100 degreeC, and the winding composite sheet material was obtained. In this apparatus, the drainage liquid in the drainage part and the ethanol in the exhaust of the dry part are recovered by the solvent recovery apparatus and reused. For this reason, the dry part was completely sealed and filled with nitrogen gas to prevent the ignition and combustion of ethanol. The physical properties of the composite sheet material are as follows. As a result, water pressure resistance of the composite sheet (400mmH ₂ O) It was confirmed that a significant improvement compared with the water pressure resistance (150mmH ₂ O) of the nonwoven fabric.
Weight per unit area: 20 g / m ² (SMS: 15 g / m ² , fine fibrous cellulose: 5 g / m ² )
Water pressure resistance: 400mmH ₂ O

<Production of water repellent paint>
50 parts by weight of an olefin-based water repellent (trade name: Petrox P300, manufactured by Meisei Chemical Co., Ltd.) and 48 parts by weight of a styrene butadiene resin (product name: SMARTEX PA3802, manufactured by Nippon A & L Co., Ltd.) are mixed with stirring to mix the main agent. After the preparation, immediately before coating, 2 parts by weight of a zirconium carbonate-based crosslinking agent (product name: Baycoat 20 manufactured by Nippon Light Metal Co., Ltd.) was added with stirring, and water was added to prepare a paint having a total solid content of 40% by weight. . At this time, the viscosity of the paint was 95 mPa · S, and it was 17 seconds by the Zahn cup method.

The properties of the olefin-based water repellent, styrene butadiene resin and zirconium carbonate-based crosslinking agent used here are as follows.
(Product name: Petrox P300, manufactured by Meisei Chemical Co., Ltd.)
Ingredient: Wax emulsion Appearance: White liquid pH: 8.5
Ionicity: Nonion Solid content concentration: 34% by weight

(Nippon A & L Co., Ltd., trade name: Smartex PA3802)
Ingredients: Styrene-Butadiene Latex Monomer Composition: Butadiene 30, Styrene 59, MMA3, ACN5, Acid 3
Tg: 21 ° C
Average particle size: 200 nm
Appearance: White liquid pH: 6.1
Ionicity: Anion Solid content concentration: 48% by weight

(Nippon Light Metal Co., Ltd., trade name: Baycoat 20)
Ingredient: ammonium zirconium carbonate Chemical formula: (NH ₄ ) ₂ [Zr (CO ₃ ) ₂ (OH) ₂ ]
Appearance: Colorless-light yellow transparent liquid pH: 9.0-9.5
Ionicity: Anion Solid content concentration: 20% by weight

<Preparation of breathable water-resistant sheet by application of water repellent material>
The water repellent paint was applied to the surface of the composite sheet material obtained above on the fine fibrous cellulose side with a flexo coater under the following conditions. The coating amount at this time was 2.1 g / m ² .
Anilox roll used: 130 lines Coating speed: 100 m / min Air dryer drying temperature: 100 ° C
After coating, calendaring (calendering line pressure: 100 kg / cm) was performed, and then the breathable water-resistant sheet of the present invention was produced by treating in a dryer at 120 ° C. for 30 minutes.

[Effects of calendaring process]
The physical property values before and after the calendaring process are as shown in Table 1 below. The thickness is compressed to 2/3 or less as compared with that before the treatment, and there is an effect that the product using the breathable water-resistant sheet is not bulky. In addition, the smoothness was improved from 1 second to 5 seconds, and it became possible to print a finer picture. The smoothness [coating surface] means the smoothness of the surface of the water-repellent material coated and laminated on the nonwoven fabric, and the smoothness [non-coating surface] is the smoothness of the opposite side surface.
In addition, the measurement of Table 1 was performed according to the following method.
Thickness: JIS P 8118
Gurley air permeability: JIS P 8117
Smoothness: JIS P 8119

The results of measuring the physical properties of this breathable water resistant sheet are shown below.
SMS nonwoven fabric basis weight: 15 g / m ²
Fine fibrous cellulose basis weight: 5 g / m ²
Water repellent coating amount: 2.1 g / m ²
Water repellency (JIS P 8137): R10
Water pressure resistance: 488mmH ₂ O
Gurley air permeability: 2 seconds / 100ml

In Example 1, the breathable water-resistant sheet of the present invention was obtained in the same manner except that the water-repellent material was changed to the following and the coating amount on the composite sheet was changed to 2.0 g / m ² .

<Production of water repellent paint>
50 parts by weight of an olefin-based water repellent (trade name: Petrox P300, manufactured by Meisei Chemical Co., Ltd.) and 48 parts by weight of a styrene butadiene resin (product name: SMARTEX PA3802, manufactured by Nippon A & L Co., Ltd.) are mixed with stirring to mix the main agent. After the preparation, immediately before coating, 2 parts by weight of a polyamide epichlorohydrin-based cross-linking agent (trade name: Sumirez Resin SPI-203, manufactured by Sumitomo Chemical Co., Ltd.) is added with stirring, and water is added to obtain a total solid content. A 40% by weight paint was prepared. At this time, the viscosity of the paint was 95 mPa · S, and it was 17 seconds by the Zahn cup method.

The properties of the polyamide epichlorohydrin-based crosslinking agent (trade name: Sumirez Resin SPI-203 manufactured by Sumitomo Chemical Co., Ltd.) used here are as follows.
Ingredient: Polyamide epichlorohydrin Appearance: Colorless-light yellow transparent liquid pH: 6.0-8.0
Ionicity: cation Solid content concentration: 50% by weight

[Comparative Example 1]
The composite sheet material obtained in Example 1 was calendered (calendar line pressure: 100 kg / cm) to obtain a comparative sheet on which no water repellent material was applied.

[Comparative Example 2]
The composite sheet material obtained in Example 1 was coated only with a silicone-based water repellent (trade name: POLON MWS, manufactured by Shin-Etsu Chemical Co., Ltd.) as follows to obtain a comparative sheet.
The properties of the silicone water repellent (trade name: POLON MWS, manufactured by Shin-Etsu Chemical Co., Ltd.) are as follows.
Ingredient: Silicone emulsion Appearance: White liquid Ionicity: Anion Solid content: 30% by weight

<Coating of silicone water repellent>
On the surface of the fine fibrous cellulose side of the composite sheet material, a paint obtained by diluting the above silicone-based water repellent with water to a solid content concentration of 10% by weight is hand-painted with a bar, and the coating amount is 2.1 g / m ² . A sheet was produced. After coating, the dryer was treated at 120 ° C. for 30 minutes, and then calendared at a linear pressure of 100 kg / cm.

[Comparative Example 3]
The composite sheet material obtained in Example 1 was coated only with a fluorine-based water and oil repellent (trade name: Solvera PT5045 manufactured by Solvay Solexis Co., Ltd.) as follows to obtain a comparative sheet.
The properties of the fluorine-based water / oil repellent (trade name: Solvera PT5045 manufactured by Solvay Solexis Co., Ltd.) are as follows.
Ingredient: Fluorine-based dispersion Appearance: Transparent amber solution pH: 7-9
Solid content concentration: 20% by weight

<Coating of fluorinated water and oil repellent>
On the surface of the composite sheet material on the fine fibrous cellulose side, a paint obtained by diluting the above-mentioned fluorinated water and oil repellent with water to a solid content concentration of 10% by weight is hand-painted with a bar, and the coating amount is 2.2 g / m ^2. A sheet of was prepared. After coating, the dryer was treated at 120 ° C. for 30 minutes, and then calendared at a linear pressure of 100 kg / cm.

[Comparative Example 4]
The composite sheet material obtained in Example 1 was coated with only the olefinic water repellent used in Example 1 (trade name: Petrox P300, manufactured by Meisei Chemical Co., Ltd.) as follows. Got.

<Coating of olefinic water repellent>
On the surface of the fine fibrous cellulose side of the composite sheet material, a paint obtained by diluting the above olefinic water repellent with water to a solid content concentration of 10% by weight is hand-painted with a bar, and the coating amount is 2.0 g / m ² . A sheet was produced. After coating, the dryer was treated at 120 ° C. for 30 minutes, and then calendared at a linear pressure of 100 kg / cm.

[Comparative Example 5]
The composite sheet material obtained in Example 1 was coated with a water repellent material using an acrylic water repellent as follows to obtain a comparative sheet.

<Production of water repellent paint>
50 parts by weight of acrylic water repellent (Syden Chemical Co., Ltd., trade name: Cybinol EK-752) and 48 parts by weight of styrene butadiene resin (Japan A & L, trade name: Smartex PA3802) were mixed with stirring. After preparing the main agent, immediately before coating, 2 parts by weight of a polyamide epichlorohydrin-based cross-linking agent (trade name: Sumirez Resin SPI-203, manufactured by Sumitomo Chemical Co., Ltd.) is added with stirring, and water is added to the whole. A paint having a solid content of 40% by weight was prepared. At this time, the viscosity of the paint was 95 mPa · S, and it was 17 seconds by the Zahn cup method.

The properties of the acrylic water repellent (trade name: Cybinol EK-752, manufactured by Saiden Chemical Co., Ltd.) are as follows.
Ingredient: Acrylic polymer emulsion Appearance: White liquid pH: 8.0-9.0
Ionicity: Anion Solid content concentration: 46% by weight

(Water-repellent paint coating)
The water repellent coating material was applied to the surface of the composite sheet material on the fine fibrous cellulose side with a flexo coater under the following conditions. The coating amount at this time was 2.3 g / m ² .
Anilox roll used: 130 lines Coating speed: 100 m / min Air dryer drying temperature: 100 ° C
After coating, calendaring (calendering line pressure: 100 kg / cm) was performed, and then a dryer was processed at 120 ° C. for 30 minutes to prepare a comparative sheet.

Next, the following evaluation was performed on the sheets obtained in Example 1, Example 2, and Comparative Examples 1-5.
(Breathability)
The air permeability of the sheets obtained in Example 1, Example 2 and Comparative Examples 1 to 5 was measured using a Gurley densometer (JIS P 8117). The results are shown in Table 2 below. As is apparent from Table 2, the air permeability after Example 1 was low and the air permeability was very good, but Example 2 was slightly deteriorated in air permeability after the calendar process due to the difference in the crosslinking agent. There is a good level. On the other hand, since the water-repellent material of Comparative Example 5 was easy to form a film, the air permeability after the calendar treatment was an air permeability close to that of the current back sheet (microporous film), and had a practical problem.

〔water resistant〕
The water resistance tests of the sheets obtained in Example 1, Example 2, and Comparative Examples 1 to 5 were performed by the following method. That is, 10 sheets of wiper paper (product name: Kim Towel, manufactured by Crecia Co., Ltd.) with a sufficient amount of water on the filter paper are placed on top of each other. The observation method was taken.

  The results of the water resistance test are shown in Table 3 below. As is apparent from Table 3, in Example 1, there was no leakage to the filter paper until 5 hours later, and the water resistance was very good. In Example 2, no leakage was observed until 2 hours, and the water resistance was relatively good although it was inferior to Example 1. On the other hand, in Comparative Example 1, water leakage occurred after 1 minute. In Comparative Examples 2 to 5, water leakage occurred after 10 to 15 minutes, and it could not be said to have sufficient water resistance. Since the conditions of the water resistance test are conditions more severe than the actual use conditions of a back sheet of a commercially available diaper for children, the breathable water resistant sheet according to the present invention (Example 1 and Example 2) is used for a commercially available child. Even if it is used for a diaper backsheet, there is no risk of leakage for a long time, and it can sufficiently withstand actual use.

  An example that demonstrates that the breathable water-resistant sheet obtained in Example 1 can be applied to the back sheet portion of a diaper for children will be described. As for the diaper, an actual wearing test was conducted in which a baby is actually worn by replacing the back sheet portion of a commercially available diaper with the breathable water-resistant sheet of the present invention. As an evaluation, it was decided to observe the appearance of urine leakage, skin irritation, and rash after a predetermined period of time after wearing.

<Production of test diapers>
From the back sheet side of the children's diaper (product name: “Moony Noble Fit” manufactured by Unicharm Co., Ltd.) configured as shown in FIGS. 5 and 6, the entire back sheet (laminate of breathable film and nonwoven fabric) is used as the joint. Carefully removing the cold spray while spraying, 40 children's diapers for testing were newly replaced with the breathable water-resistant sheet according to the present invention.

<Actual wearing test by infants>
Forty test diapers were prepared and worn by eight infants (four boys and four girls) with a normal urination mechanism (use five per person). The wearer's guardian was asked to record the state of use, and all diapers after use were collected to confirm leakage from the backsheet. The wearing time was 3 hours on average. As a result, no leakage from the back sheet occurred in 35 out of 40 sheets. Further, in the case of three sheets, a circular ooze occurred in the rear part, and in the case of two sheets, a pinhole-like ooze occurred, but it was not a problem that was practically problematic. Moreover, there was no stuffiness or fogging while wearing on all infants. From these results, it was confirmed that the children's diaper using the breathable water-resistant sheet of the present invention as a back sheet is sufficiently practical.

It is typical sectional drawing of an example of the air permeable waterproof sheet of this invention. It is typical sectional drawing of an example of the air permeable waterproof sheet of this invention. It is a flowchart of the manufacturing method of the air permeable waterproof sheet of this invention. It is a schematic diagram of the manufacturing apparatus used for the manufacturing process of the air permeable waterproof sheet of this invention. It is the top view which developed the disposable paper diaper which is an example of the absorber article of the present invention. It is sectional drawing of AB in FIG.

Explanation of symbols

1 Composite sheet material 2 Water repellent material

Claims (7)

  A breathable water-resistant sheet obtained by laminating a water-repellent material on a composite sheet material composed of a nonwoven fabric and fine fibrous cellulose, wherein the water-repellent material contains an olefin-based water-repellent agent, a synthetic resin-based binder, and a crosslinking agent. Features a breathable water-resistant sheet.   The breathable water-resistant sheet according to claim 1, wherein the nonwoven fabric is a spun melt nonwoven fabric.   The breathable water-resistant sheet according to claim 1 or 2, wherein the fine fibrous cellulose has an average fiber length of 0.3 mm or less and a water retention of 15 mL / g or more.   The breathable water-resistant sheet according to any one of claims 1 to 3, wherein the synthetic resin binder is made of a styrene butadiene resin.   The breathable water-resistant sheet according to any one of claims 1 to 4, wherein the crosslinking agent is made of ammonium zirconium carbonate.   The breathable water-resistant sheet according to any one of claims 1 to 5, wherein the breathable water-resistant sheet is calendered.   An absorbent article, wherein the breathable water-resistant sheet according to any one of claims 1 to 6 is used as a back sheet.

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