JPH0425444A - Moisture-permeable nonwoven fabric composite sheet - Google Patents

Abstract

PURPOSE:To obtain a nonwoven fabric composite sheet, a surface of which has a hydrophilic nature and which has high water resistance though it has moisture permeability, by bonding a nonwoven-fabric having water repellency of a specific value or less and a web having water resistance of a specific value or more. CONSTITUTION:At least one surface is coated with a hydrophilic nonwoven fabric having the surface of water repellency of 70 points or less, and the nonwoven fabric layer and a layer including a wab having water resistance of 50cm or more are bonded and unified in a discontinuous manner with a bonding resin having an equilibrium moisture rate of 3% or less. The nonwoven fabric having the water repellency of 70 points or less of a surface can be acquired through a wet type method, a dry type method such as a card method, a random web method, etc., and a span bonding method, etc., from fibers having the equilibrium moisture rate of approximately 4% or more or fibers, into which these fibers are mixed. The nonwoven fabric having water resistance of 50cm or more is represented by polypropylene. A polyolefin resin, etc., having moisture content of approximately 0% can be obtained by the nonwoven fabric through an MB method.

Description

[Detailed Description of the Invention] <Industrial Application Field> The product of the present invention has a parent wood surface, water absorbency, moisture permeability, and high water resistance that makes it difficult for water to pass through. It can be used in a wide range of fields, including cover materials for sanitary materials such as disposable diapers, work clothes, drapes used in hospitals, bed sheets, bedwetting mats, and packaging materials for preserving freshness.

<Prior Art> In a nonwoven fabric obtained by the melt blown (hereinafter referred to as MB) method, the fineness (diameter) of the single fibers constituting the nonwoven fabric is small. Therefore, the interfiber voids of the nonwoven fabric can be several microns or less. M from hydrophobic resins such as polypropylene
If B nonwoven fabric is made, a nonwoven fabric that has breathability and a certain degree of waterproofness, that is, water resistance as referred to in the present invention, can be obtained.

On the other hand, MB nonwoven fabric has less strength because the molecular orientation of its constituent fibers is not as advanced as that of general-purpose fibers.

Therefore, as shown in Special Publication No. 60-11148 <MB
Non-woven fabrics and strong spunpond non-woven fabrics are fused together and used in work clothes, surgical gowns used in hospitals, drapes, sterilization wraps, etc. In this way, by laminating the MB nonwoven fabric and the spunpond, it is possible to obtain a composite sheet that has sufficient strength, air permeability, and high water resistance. However, if high water resistance is required, the current situation is that the sheet surface must be water repellent. For example, if a MB nonwoven fabric made of polypropylene with a water resistance of 65 crrl is sandwiched between nylon spunpons coated with a hydrophilic oil agent, and the three layers are fused together, the surface will certainly be hydrophilic and absorb liquid. However, the water resistance drops to about 3 cm. In other words, the current situation is that if the surface is made hydrophilic, the water resistance will decrease.

<Means and effects for solving the problem> The present inventors have conducted intensive studies to solve the above-mentioned problem, and as a result, have completed the present invention. That is, at least one surface is covered with a hydrophilic nonwoven fabric having a surface water repellency of 70 points or less, and the nonwoven fabric layer and a layer containing a web having a water resistance of 50 cm or more have an average moisture content of 3% or less. It has a hydrophilic surface characterized by being integrally bonded discontinuously with an adhesive resin and has a water resistance of 50c.
It is an object of the present invention to provide a moisture permeable nonwoven fabric composite sheet having a moisture permeability of at least m.

Here, the water repellency is JIS L-1092 (spray method),
Water resistance is measured by JIS L-1092A method (low water pressure method), and equilibrium moisture content is measured by JIS L-1096.

Nonwoven fabrics with a surface water repellency of 70 points or less can be obtained by various methods, but fibers such as cotton, rayon, vinylon, or nylon having an average water content of about 4% or more, or those fibers It can be easily obtained from the mixed fibers by a wet method, a card method, a dry method such as a random web method, or a spun-pond method. Even if the fibers on the surface are hydrophobic, a surface material with a water repellency of 70 points or less can be obtained by adding a hydrophilic surfactant or incorporating a hydrophilic component. In the present invention, the water repellency is preferably at least 70 points or less, but if hydrophilicity and liquid absorption are particularly desired, the water repellency is more preferably lower than 30 points.

Next, a nonwoven fabric having a water resistance of 50 cm or more can be easily obtained by making a polyolefin resin, typified by polypropylene, with a moisture content of about 0% into a nonwoven fabric by the MB method. At this time, if the average fiber diameter is set to 10 microns or less, or even several microns or less, an MB nonwoven fabric with high water resistance can be obtained. Further, by flat heat calendering, it is possible to improve water resistance while maintaining moisture permeability and air permeability. In order to obtain an MB nonwoven fabric having the water resistance required for the present invention, the basis weight of the nonwoven fabric must be 15 g/m2 or more. By adjusting factors such as the diameter of the fibers constituting the MB nonwoven fabric, thermal calendar treatment, and basis weight, it is possible to improve water resistance while maintaining moisture permeability and air permeability, and the effects of the present invention are further enhanced. It becomes something big.

In the present invention, the MB web may be used as it is, but the MB web may be laminated with a hydrophobic material with an average water content close to 0%, such as polypropylene spunpond or polypropylene knitted fabric, or the MB web may be laminated with a hydrophobic material such as polypropylene spunpond or polypropylene knitted fabric, or the MB web may be laminated with a hydrophobic material such as polypropylene spunpond or polypropylene knitted fabric. A laminate in which materials are sandwiched in a sandwich-like manner and fused together may be used.

In order to integrate the hydrophilic surface material and the layer containing the MB web, an adhesive resin having an average moisture content of 3% or less, preferably 1% or less, is applied in a discontinuous manner so as not to form a film. , the surface material and the layer containing the MB web are interposed between the surface material and the layer containing the MB web, pressure is applied, and if necessary, heating and pressure is applied to bond the surface material and the layer containing the MB web. As the adhesive resin, an olefin resin or acrylic resin into which a functional group is introduced is used. Adhesion can be achieved by chemical or physical methods, including fusion, adhesion, etc., or by a combination of these mechanisms. When a thermoplastic resin having a melting point is used as the adhesive resin, the melting point is preferably lower than the softening point of the MB resin (the temperature at which changes begin in differential thermal analysis), and the composition of the surface material contains thermoplastic fibers. If the melting point is lower than the melting point of the fiber, it is more preferable.

In order to prevent the composite sheet of the present invention from losing its moisture permeability, the adhesive resin needs to be interposed continuously between the surface material and the layer containing the MB web, i.e. discontinuously so as not to form a film. . In addition, the equilibrium moisture content of the adhesive resin is 3
%, it is not preferable because the water resistance of the obtained nonwoven fabric composite sheet decreases.

EXAMPLES In order to make the content of the present invention easier to understand, examples will be described below, but the present invention is not limited to these examples.

Example 1 An MB web having a basis weight of 30 g/m'' and an average fiber diameter of 4 microns was obtained by the MB method from a polypropylene resin with a moisture content of 0%. Thickness: 0.1mm.

An MB nonwoven fabric having a water resistance of 90c+n and a softening point of 115°C was produced.

On the other hand, a hydrophilic surfactant was applied to a nylon spun surface material having a water repellency of 0 points and a basis weight of 25 g/m. 0.01% ethylene-vinyl acetate resin was applied at a rate of 8 g/m'' in dots (polka dots), ie, discontinuously, at intervals of about 5 mm.

Next, sandwich the MB nonwoven fabric with nylon spun pads with the resin-coated side facing inside.
The treatment was carried out continuously while being pressurized with a hot roll heated to 100°C. As a result, a three-layer laminated nonwoven fabric composite sheet was obtained in which a MB nonwoven fabric was placed in the center and nylon spunponds were placed on both sides.

This non-woven composite sheet has a water repellency of 0 points on both surfaces,
It has water absorption properties, and has a moisture permeability of 300 g/m"・hr according to the JIS L-1099A-1 method, and a water resistance of 88 cm.
showed that.

When the nonwoven composite sheet obtained in this way was used as a mat cover for a hospital bed, it did not feel stuffy, and while the surface absorbed liquid spilled on the bed, it also prevented the liquid from passing through to the mat, causing it to become dirty. That never happened.

Comparative Example 1 The MB nonwoven fabric and nylon spunpond used in Example 1 were used in the same way as in Example 1, with the MB nonwoven fabric in the center and nylon spunponds placed on both sides, and the three layers were partially and discontinuously formed by heat embossing. Integrated by fusion. The nonwoven composite sheet thus obtained was hydrophilic on both surfaces and had moisture permeability, or its water resistance was reduced to 5 cm.

Even if this sheet is used as a cover for a bed mat as in Example 1, liquid spilled on the bed will penetrate into the mat.
It was not possible to prevent the mat from becoming dirty.

Example 2 An MB web having a basis weight of 20 g/m 2 , an average fiber diameter of 3.5 microns, and a softening point of 105° C. was obtained from a polypropylene resin. This web was sandwiched between polypropylene spunpons having a basis weight of 15 g/m'' to which no surfactant was added, and fused and integrated using a discontinuous pattern in which the Empon area was 16% of the total area.The obtained MB web (three-layer laminate) had a water resistance of 77 cm.

On the other hand, a dry nonwoven fabric having a basis weight of 30 g/m2 and a water repellency of 0 points was obtained from rayon staples.

Next, ethylene/ethyl acrylate/maleic anhydride terpolymer powder having a melting point of 85°C and an average water content of 0.1% is dispersed on the layer containing MB at a rate of 15 g/m2, and then A dry nonwoven fabric was polymerized and the two were pressed together using a 90°C heated roll.

The rayon dry nonwoven fabric side of the obtained nonwoven fabric composite sheet exhibited excellent water absorption, with a water vapor permeability of 320 g/m''·hr and a water resistance of 75 cm.

<Effects of the Invention> According to the present invention, it is possible to obtain a nonwoven fabric composite sheet that has a hydrophilic surface, moisture permeability, and high water resistance, and its utility value is extremely high.

Special fraud applicant RiRashi Co., Ltd. Representative Patent Attorney Ken Mizuki

Claims (1)

[Claims] At least one surface is covered with a hydrophilic nonwoven fabric having a surface water repellency of 70 points or less, and the nonwoven fabric layer has a water resistance of 50 points or less.
It has a hydrophilic surface characterized by being integrally bonded with a layer containing a web having an average moisture content of 3% or less in a discontinuous manner, and has a water resistance of 50cm or more. Moisture-permeable nonwoven composite sheet.