JPH10264321A - Laminated sheet and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a laminated sheet efficiently at a low cost while the laminated sheet which has a good water vapor permeability and a soft touch, and is suitable as a back sheet of sanitary goods such as a diaper or the like, is provided. SOLUTION: A water vapor permeable resin film is preferably composed of (a) 60-100 wt.% of water vapor permeable elastomer resin, and (b) 40-0 wt.% of polyethylene resin having 0.925 g/m<3> or under density and 8-30 μm thickness, and a laminated sheet is provided wherein nonwoven fabric is partially so joined as to have 5-20% of an area of the joined part, preferably a pitch of the joined part is 1.8 mm or over, and the area of the joined part of one piece is 7 mm or under. Further, a laminated layer manufacturing method is provided wherein a metal made roll having a recessed and projected state in which a pitch of a projected part is 1.8 mm or over, an area of one piece of the projected part is 7 mm or under, and further a height of the projected part is 0.5 mm or over.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated sheet obtained by partially joining a moisture-permeable resin and a nonwoven fabric, and more particularly to a laminated sheet preferably used as a back sheet for sanitary articles such as diapers, and a method for producing the same.

[0002]

2. Description of the Related Art In sanitary articles such as diapers, resin products are widely used as a back sheet. The performance required of the back sheet is liquid impermeability such that urine and other liquids do not leak. It is necessary to have moisture permeability so as not to cause skin irritation or the like due to stuffiness, and to have a soft and good texture.

Conventionally, to satisfy these, for example,
A laminated sheet in which a moisture-permeable resin such as polyurethane is laminated to a nonwoven fabric by heat or an adhesive is known, but in order to smoothly perform a laminating process, the moisture-permeable resin layer must be thickened to some extent. As a result, there was a problem that the moisture permeability was reduced and the softness was also poor. In order to solve such a problem, a method has been proposed in which a moisture-impermeable resin is directly laminated on a nonwoven fabric and then moisture-permeable is imparted. As one of the methods, for example, a method of extruding a thermoplastic resin to which a filler such as an inorganic filler is added, joining the extruded thermoplastic resin to a nonwoven fabric, and then performing stretching to generate micropores to impart air permeability (Japanese Patent Application Laid-Open No.
No. 135231) or a resin composition obtained by adding a filler such as an inorganic filler and a liquid component having heat resistance to a thermoplastic resin, extruding the resin composition, laminating the resin composition on a porous substrate such as a nonwoven fabric, and then press-bonding with a roll to form a void. (Japanese Patent Application Laid-Open No. 02-162008).

[0004] However, in any of these, there is a problem that an increase in cost is unavoidable due to complicated processing steps, and a soft texture cannot be obtained due to the entire surface joining in terms of performance. Therefore, there has been a demand for a sheet that satisfies the performance required for a back sheet, such as good moisture permeability and soft texture, and a method of manufacturing the sheet that can be mass-produced at low cost.

[0005]

SUMMARY OF THE INVENTION The present invention provides a laminated sheet having good moisture permeability and soft texture under such circumstances and suitable as a back sheet for sanitary articles such as diapers. is there. Further, the present invention provides a method for manufacturing the laminated sheet at low cost and efficiently.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that, preferably, a melt-extruded moisture-permeable resin and a nonwoven fabric are partially joined so that the area of the joining portion becomes a specific value or less. As a result, it has been found that the object can be achieved. The present invention has been completed based on such findings.

That is, the present invention provides the following laminated sheet:
It is an object of the present invention to provide a method of manufacturing the same. (1) A laminated sheet in which a moisture-permeable resin film and a nonwoven fabric are laminated and partially bonded so that the area of the bonded portion is 5 to 20%. (2) The laminated sheet according to (1), wherein the pitch of the joints is 1.8 mm or more, and the area of one joint is 7 mm ² or less. (3) The moisture-permeable resin film is composed of (a) a moisture-permeable elastomer resin of 60 to 100% by weight and (b) a density of 0.925.
The laminated sheet according to the above (1) or (2), wherein the laminated sheet comprises 40 to 0% by weight of a polyethylene resin having a g / cm ³ or less, and the thickness of the moisture-permeable resin film portion is 8 to 30 μm. (4) The nonwoven fabric is selected from a spunbonded nonwoven fabric, a composite nonwoven fabric of a spunbonded nonwoven fabric and a meltblown nonwoven fabric, and a nonwoven fabric obtained by heat-sealing composite short fibers, and has a basis weight of 10 to 30 g / a m ² (1) to
The laminated sheet according to any one of (3). (5) The laminated sheet according to any one of the above (1) to (4), wherein the moisture-permeable resin film is obtained by melt extrusion molding. (6) In a method of manufacturing a laminated sheet by passing a moisture-permeable resin film and a nonwoven fabric between a pair of rolls, a surface in contact with the moisture-permeable resin film or the nonwoven fabric on one of the pair of rolls. Has a plurality of projections, the pitch of the projections is 1.8 mm or more, the area of one projection is 7 mm ² or less, and the height of the projections is 0.5 m
(1) to (5) using a metal roll having a diameter of at least m.
The method for producing a laminated sheet according to any one of the above.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. 1. Moisture-permeable resin film In the moisture-permeable resin film constituting the laminated sheet according to the present invention, the resin to be used is not particularly limited as long as it is a thermoplastic resin having moisture permeability. It is preferable to appropriately select one or a combination of a plurality of thermoplastic resins having water vapor permeability, such as a series thermoplastic elastomer.

In the present invention, these thermoplastic resins having moisture permeability may be used alone, but from the viewpoint of production cost, other thermoplastic resins are used in combination within a range where the desired moisture permeability can be ensured. Is preferred. In this case, as the other thermoplastic resin to be used, a polyethylene resin, particularly a polyethylene resin having a density of 0.925 g / cm ³ or less, an ethylene-vinyl acetate copolymer (EVA resin), or the like is preferable since it has softness. Used.

Specifically, (a) the moisture-permeable elastomer resin is 60 to 100% by weight, preferably 60 to 85% by weight, more preferably 60 to 70% by weight, and (b) the density is 0.925 g / cm. 4 polyethylene resins less than ³
Those comprising 0 to 0% by weight, preferably 40 to 15% by weight, more preferably 40 to 30% by weight are suitably used. As the moisture-permeable elastomer resin (a), a polyurethane thermoplastic elastomer is more preferably used, and as the polyethylene resin (b), a density of 0.9 is used.
Low density polyethylene (LDPE) of 25g / cm ³ or less
And linear low-density polyethylene (LLDPE) are preferred, but if it exceeds 0.925 g / cm ³ , good softness may not be obtained. If the moisture-permeable elastomer resin (a) is less than 60% by weight, satisfactory moisture permeability may not be obtained. Further, it is desirable from the viewpoint of moldability that the melt viscosities of the moisture-permeable elastomer resin (a) and the polyethylene resin (b) are close to each other. Further, a compatibilizer such as maleic anhydride, modified polyethylene, and modified ethylene-vinyl acetate copolymer may be added to the moisture-permeable elastomer resin (a) and the polyethylene resin (b).

The thickness of the moisture-permeable resin film is 8 to 30 μm.
m, more preferably 10 to 25 μm, even more preferably 10 to 20 μm. If it exceeds 30 μm, moisture permeability may be insufficient or flexibility may be impaired,
If it is less than 8 μm, pinholes are likely to occur, and good liquid impermeability may not be obtained. As a method for producing a moisture-permeable resin film, melt extrusion molding using a known film molding machine such as a T-die is suitably used. 2. Nonwoven fabric The nonwoven fabric constituting the laminated sheet according to the present invention includes:
This includes not only nonwoven fabric products that have undergone a bonding process such as thermal bonding or bonding with an adhesive, but also so-called nonwoven webs that have not undergone these bonding processes. The fiber used is not particularly limited, but polypropylene,
Polyethylene, polyethylene terephthalate (PE
T), polyurethane, cellulosic fibers and composite fibers thereof are preferably used. Among them, polypropylene is more preferably used. There is also no particular limitation on the method for producing the nonwoven fabric, and it is appropriately selected from the methods that provide flexibility and bulkiness. Spunbond, spunlace, hot air card,
It can be manufactured by a known method such as a hot embossed card or a melt blow. Among them, the following method is preferably used from the viewpoints of securing air permeability and softness.
For example, the spun bond method is preferable because it can be manufactured in one step, and a bulky and soft material having excellent hydrophobicity is easily obtained. In addition, composite fibers of the spun bond method and the melt blow method, specifically, composite fibers of the spun bond method / melt blow method / spun bond method, and composite fibers of the spun bond method / melt blow method, It has excellent performance that there is no unevenness in weight, the appearance is good, and the excrement is highly concealable. Moreover,
A conjugate short fiber (for example, polyethylene and polyethylene terephthalate) formed into a sheet using a card machine and heat-sealed with hot air, hot embossing, or the like is also preferable because it is soft and has high concealability of excrement. Such a conjugate short fiber includes a side-by-side type and a core-sheath type.

The basis weight of the nonwoven fabric is not particularly limited, but is 10 to 30 g / m ² , preferably 15 to ²⁰ g / m ² .
² If it exceeds 30 g / m ² , the nonwoven fabric itself may become thick and lack softness.
If it is less than 0 g / m ² , there is a problem that it is difficult to obtain industrially stable quality. 3. Laminated sheet The laminated sheet according to the present invention is characterized in that the moisture-permeable resin film and the nonwoven fabric are laminated, and the area of the joint portion is 5 to 20%.
The laminated sheet is preferably partially joined so as to have a content of 5 to 15%. Here, the laminated sheet includes a multilayer sheet in which the above-described laminated sheet composed of two layers is laminated with another sheet. In these cases, the types of other sheets are not particularly limited. If the area of the joining portion exceeds 20%, it becomes sheet-like, and the cloth-like texture may be impaired.
If it is less than 1, there is a possibility that a sufficient adhesive strength cannot be obtained. Examples of the shape of the joint portion include a stripe shape, a grid shape, and a dot shape, and a dot shape is preferably used from the viewpoint of softness. The dot shape includes polygonal shapes such as a round shape, a triangular shape, and a square shape, but is not particularly limited. It is preferable in terms of softness that the pitch of the joining portions, that is, the distance between the center points of the joining portions is 1.8 mm or more, and the area of one joining portion is 7 mm ² or less. It is desirable that the joining portions are uniformly distributed without being unevenly distributed in the laminated portion. In the method of manufacturing a laminated sheet by passing a moisture-permeable resin film and a nonwoven fabric between a pair of rolls,
Either one has a plurality of convex portions on the surface in contact with the moisture-permeable resin film or the nonwoven fabric, and the pitch of the convex portions is 1.8.
and the mm or more, the area of one of the projections is not more 7 mm ² or less, the laminated sheet according to claim 1, further height of the convex portion is used a metal roll is 0.5mm or more Manufacturing method. 4. Method for Producing Laminated Sheet The method for producing the laminated sheet according to the present invention is not particularly limited, but the following method is preferably used.

That is, a moisture-permeable resin sheet obtained by melt extrusion.
And a nonwoven fabric are laminated by passing between a pair of rolls.
According to the method, a pair of rolls used at this time
Of either the moisture permeable resin film or the
It has a plurality of protrusions on the surface in contact with the woven fabric, and the pitch of the protrusions
Is 1.8 mm or more, and the area of one protrusion is 7 mm. ^Two
Or less, and the height of the convex portion is 0.5 mm or more.
It is preferable to use one made of a metal. The pitch of the projections
1. It is less than 8 mm or the area of one projection is 7
mm^TwoWhen it exceeds, softness may be lost.
It is desirable that the height of the projection is 0.5 mm or more.
If the height of the
The resin sheet layer enters the non-woven fabric layer
There is a possibility that the state may not be understood.

The roll to be used may be any one of a pair of rolls as long as one of the rolls has a plurality of convex portions on a surface in contact with the moisture-permeable resin sheet or the nonwoven fabric.
A method in which a nip roll having a convex portion on its surface is pressed against a cooling roll is preferably used. Here, usually, the rubber nip roll and the metal cooling roll are used, but in the present invention, the stability of the surface temperature due to its durability and ease of temperature adjustment, and furthermore, the joining based on the stability From the viewpoint of the strength and the like, it is desirable that the roll having the unevenness on the surface is made of metal. Further, both the roll having the unevenness on the surface and the cooling roll may be made of metal.

[0015]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The properties of the obtained laminated sheet were evaluated by the following methods. Moisture permeability: 40 ° C, 90 according to JIS L1099 method
The moisture permeability at% relative humidity was measured.

Flexibility: KES-F manufactured by Kato Tech
A pure bending test was performed using a B2 type machine to measure rigidity. Hand: Sensory evaluation by hand was performed by six testers. Four levels of △ ○ か × were evaluated as to whether or not there was a feeling of being bulky and soft and close to a cloth. Example 1 As a moisture-permeable resin film, 60% by weight of a polyurethane resin (trade name “Elastollan OH-3 / 37U” manufactured by Takeda Birdish Urethane Industry Co., Ltd.) and linear low density polyethylene (LLDPE) (Idemitsu) Petrochemical Co., Ltd., trade name “Idemitsu Polyethylene-L 0134L” (density 0.920 g / cm ³ , MI = 1.2 g / 10 min) 4
While melt extruding a resin composition containing 0% by weight with a T-die molding machine, a non-woven fabric (polypropylene spun bond (PP spun bond) non-woven fabric, manufactured by Idemitsu Petrochemical Co., Ltd .;
² ) was partially wound with an uneven nip roll and wound up.
The processing conditions are as follows.

Extrusion temperature: 270 ° C. Extruded amount: 150 kg / h Take-off speed: 90 to 100 m / min (film thickness of 10 ± 2 μm)
m. ) Convex (emboss) side roll Material: SS41, Convex area: 8% of total Convex shape: Tip 0.8φ pin, Convex pitch: 2.5
mm Height of convex portion: 1.0 mm Table 1 shows the properties of the obtained laminated sheet.

[0018]

[Table 1]

[Example 2] In Example 1, the nonwoven fabric was obtained by fusing polyethylene terephthalate / polyethylene composite short fibers with hot air (trade name "H-23" manufactured by Kuraray Co., Ltd .; was replaced by m ²⁾⁾ was performed in the same manner as in example 1. Table 1 shows the properties of the obtained laminated sheet. Example 3 In Example 1, a polyurethane resin (trade name “Elastollan OH-3 / 37U”, manufactured by Takeda Birdish Urethane Industry Co., Ltd.) was used as the moisture-permeable resin film.
70% by weight of linear low density polyethylene (LLDP)
E) (made by Idemitsu Petrochemical Co., Ltd., trade name "Idemitsu Polyethylene-
L 0134L "(density 0.920 g / cm ³ , MI =
1.2 g / 10 min)) The procedure of Example 1 was repeated, except that the resin composition was changed to 30% by weight.

The properties of the obtained laminated sheet are shown in Table 1. [Example 4] In Example 3, the nonwoven fabric was replaced with a polyethylene terephthalate / polyethylene composite hot air card nonwoven fabric (trade name "H-23", manufactured by Kuraray Co., Ltd .;
² ) In the same manner as in Example 3 except that the above was used.

The properties of the obtained laminated sheet are shown in Table 1. [Comparative Example 1] In Example 1, a linear low-density polyethylene (LLDPE) (trade name “Idemitsu Polyethylene-L 0134L”, manufactured by Idemitsu Petrochemical Co., Ltd.) was used as the moisture-permeable resin film without using a polyurethane resin. 0.92
0 g / cm ³ , MI = 1.2 g / 10 min)) 100% by weight
Was used. That is, LLDPE which is a moisture-impermeable resin
The procedure was performed in the same manner as in Example 1 except for using only.

Table 1 shows the properties of the obtained laminated sheet. Comparative Example 2 In Example 2, a linear low-density polyethylene (LLDPE) (trade name “Idemitsu Polyethylene-L 0134L” (manufactured by Idemitsu Petrochemical Co., Ltd.) without using a polyurethane resin as the moisture-permeable resin film was used. 0.92
0 g / cm ³ , MI = 1.2 g / 10 min)) 100% by weight
Was used. That is, LLDPE which is a moisture-impermeable resin
The procedure was performed in the same manner as in Example 2 except for using only.

Table 1 shows the properties of the obtained laminated sheet. [Comparative Example 3] In Example 1, the entire surface was joined using a normal flat nip roll having no unevenness, instead of the uneven nip roll. Other than that, it carried out similarly to Example 1.

The properties of the obtained laminated sheet are shown in Table 1. [Comparative Example 4] In Example 3, as the embossing-side roll, the convex area was 32% of the whole area, the convex shape was a 1.6-pin tip, the convex pitch was 2.5 mm, and the convex height was 1.0 mm. The procedure was performed in the same manner as in Example 3 except that the above-mentioned compound was used.

Table 1 shows the properties of the obtained laminated sheet. [Comparative Example 5] Nonwoven fabric (polypropylene spunbond (P
P Spunbond) non-woven fabric, manufactured by Idemitsu Petrochemical Co., Ltd. Product name “Stratec RW2020” (basis weight 20g /
m ² )) and a moisture-permeable film (trade name “Polam” (thickness: 15 μm), manufactured by Tokusoh Co., Ltd.) using 3 g / m ² of a rubber-based hot melt adhesive to form a laminated sheet.

Table 1 shows the properties of the obtained laminated sheet.

[0027]

The laminated sheet of the present invention has good moisture permeability and a soft texture, and is suitable as a back sheet for sanitary articles such as diapers. Further, the method for producing a laminated sheet of the present invention allows the laminated sheet to be produced inexpensively and efficiently.

Claims (6)

[Claims] 1. A laminated sheet in which a moisture-permeable resin film and a nonwoven fabric are laminated and partially bonded so that the area of the bonded portion is 5 to 20%. 2. The laminated sheet according to claim 1, wherein the pitch of the joining portions is 1.8 mm or more, and the area of one joining portion is 7 mm ² or less. 3. A moisture-permeable resin film comprising: (a) 60 to 100% by weight of a moisture-permeable elastomer resin; and (b) a polyethylene resin having a density of 0.925 g / cm ³ or less.
3. The laminated sheet according to claim 1, comprising 0 to 0% by weight, and the moisture-permeable resin film portion having a thickness of 8 to 30 μm. 4. 4. The nonwoven fabric is selected from a spunbonded nonwoven fabric, a composite nonwoven fabric of a spunbonded nonwoven fabric and a meltblown nonwoven fabric, and a nonwoven fabric obtained by heat-sealing composite short fibers, and has a basis weight of 10 to 10. laminated sheet according to claim 1 which is 30 g / m ^2. 5. The laminated sheet according to claim 1, wherein the moisture-permeable resin film is obtained by melt extrusion molding. 6. A method for producing a laminated sheet by passing a moisture-permeable resin film and a nonwoven fabric between a pair of rolls, wherein one of the pair of rolls is provided with the moisture-permeable resin film or the nonwoven fabric. A plurality of protrusions are provided on the surface in contact with each other, the pitch of the protrusions is 1.8 mm or more, the area of one protrusion is 7 mm ² or less, and the height of the protrusions is 0.5 mm or more. Claim 1 which uses a certain metal roll.
5. The method for producing a laminated sheet according to any one of 5.