JP4255561B2 - Method for producing hydrophilic laminated sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a hydrophilic laminated sheet obtained by laminating a hydrophobic nonwoven fabric and a water-absorbent sheet by thermal bonding, and more specifically, hydrophilicity preferably used for packaging of fresh foods such as diapers, fish and fruits. The present invention relates to a method for producing a laminated sheet.
[0002]
[Prior art]
In recent years, non-woven fabrics have been favorably used for portions that come into direct contact with the skin of diapers and the like, and portions that come into direct contact with fish and fruits in the packaging of fresh foods such as fish and fruits because of their softness and texture. In these applications, in any case, it is required as a function to directly touch and absorb moisture. In other words, diapers are required to absorb urine and the like and not cause discomfort to the skin of the wearer, and in packaging materials (drip sheets) that are in direct contact with fish or fruits, It is required to have a function of quickly absorbing moisture from fruits and the like and preventing these rots. And in order to satisfy | fill this request | requirement, what laminated | stacked the water absorbing material on the nonwoven fabric is used normally.
[0003]
However, in this laminate, if the nonwoven fabric itself is hydrophobic, although the water absorbing material is laminated, water cannot be absorbed by the water absorbing material, and the above function cannot be performed sufficiently.
Therefore, a hydrophilic treatment is performed by applying a surfactant or the like to the nonwoven fabric.
[0004]
However, if a nonwoven fabric coated with a surfactant is used as the surface material of a diaper, it may cause skin irritation due to the drug, and if used on a drip sheet for fish, fruits, etc. There is a risk of losing the flavor.
For this reason, the appearance of a water-absorbing sheet that does not use such a surfactant or the like has been desired.
[0005]
[Problems to be solved by the invention]
The present invention provides a method for producing a hydrophilic laminated sheet having sufficient water absorption performance as a result of imparting hydrophilicity to a nonwoven fabric without applying a hydrophilic treatment by applying a surfactant or the like. .
[0006]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that a hydrophilic laminated sheet obtained by laminating a hydrophobic nonwoven fabric and a water-absorbent sheet by thermal bonding can effectively solve the above problems. It was. The present invention has been completed based on such findings.
[0007]
That is, an object of the present invention is to provide the following method for producing a hydrophilic laminated sheet.
1 . Sparse aqueous non-woven fabric and absorption paper, in the manufacturing method of the hydrophilic layered sheet comprising a laminate by thermal bonding by passing between heated two embossing rolls, the embossing roll on the side contacting the hydrophobic nonwoven fabric, a hydrophobic nonwoven fabric while the low have temperature Ri by the melting point of the side embossing roll in contact with the absorption paper, hydrophilic method for producing a laminated sheet characterized by the a temperature above the melting point of the hydrophobic nonwoven fabric.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described.
1. Material of each layer constituting the hydrophilic laminated sheet according to the present invention (1) Hydrophobic nonwoven fabric (A)
As the hydrophobic nonwoven material, a thermoplastic resin, particularly an ethylene / α-olefin copolymer, and an ethylene / α-olefin copolymer mixed with another resin, preferably a polyolefin-based resin, is preferably used. Depending on the case, an antioxidant, an ultraviolet absorber, a colorant, an antistatic agent, a weathering agent and the like that are usually used for fibers and nonwoven fabrics are appropriately added. The number of carbon atoms of the α-olefin in the ethylene / α-olefin copolymer is preferably 3-18, and more preferably 3-12, and examples thereof include propylene, 1-butene, 1-hexane, 1-octene and the like. be able to.
[0009]
Examples of the hydrophobic non-woven fabric include a continuous long-fiber non-woven fabric using the above-described resin, a so-called spunbonded non-woven fabric. About the manufacturing method of this spun bond nonwoven fabric, it can manufacture by the well-known spun bond method. For example, in the spinning process, (1) a method using an ejector or air soccer using high-pressure air, (2) a method using a throttle plate to increase the air speed by sealing the air guide path using a suction blower, Or {circle around (3)} either of these methods may be used.
[0010]
As the properties of the spunbond nonwoven fabric as the hydrophobic nonwoven fabric in the present invention, the basis weight has a certain amount of voids so as not to prevent water from touching the water absorbent sheet when bonded to the water absorbent sheet by thermal bonding. Therefore, it is desirable to be in the range of 5 to 50 g / m ² , preferably 10 to 30 g / m ² . In addition, the fiber diameter is too dense if too thin, and there are too few voids to pass through, and if too thick, thermal bonding cannot be performed effectively, and the texture becomes hard, etc., 50 μm or less, Preferably it is 30 μm or less.
[0011]
The method for producing the spunbonded nonwoven fabric is not particularly limited. Specifically, the apparatus includes a 45 mmφ single-screw extruder, a spunbond die & nozzle, a cooling tower, a filament pulling device, a fiber opening device, a conveyor, and an embossing roll.・ It is recommended to use the one that consists of winding order. Moreover, it is good to use an embossing roll in a thermocompression bonding process. If the temperature of the embossing roll is too low, sufficient strength cannot be obtained and fluffing will occur, and if the temperature is too high, the web may adhere to the roll and cause troubles. It is better to set the embossing temperature.
(2) Water absorbent sheet (B)
The water-absorbent sheet (B) may be any material as long as it is made of a material having water-absorbing performance, but water-absorbent paper obtained by papermaking wood pulp is particularly preferably used. In such water-absorbent paper, the basis weight is preferably in the range of 10 to ²⁰⁰ g / m ² . If it is less than 10 g / m ² , the strength will be insufficient and it will be difficult to unwind the original fabric, and it may be difficult to laminate and heat bond. When it exceeds 200 g / m ² , it becomes difficult to heat to a temperature for thermal bonding, and there is a possibility that good thermal bonding cannot be performed.
(3) Layer made of a waterproof material (C)
In the present invention, a layer (C) made of a waterproof material may be further laminated on the water absorbent sheet layer side of the laminated sheet comprising the hydrophobic nonwoven fabric (A) and the water absorbent sheet (B). .
[0012]
The layer (C) made of a waterproof material is laminated for the purpose of preventing the water absorbed by the water-absorbent sheet layer from leaking to the outside, and the waterproof material meets this purpose. If it is a thing, there will be no restriction | limiting in particular. Specific examples include a thermoplastic resin film or a laminate including a thermoplastic resin film layer. For example, a polyethylene film, a polypropylene film, a polyethylene resin coated paper, a laminate of a polyethylene film and a non-woven fabric, a polyethylene Examples thereof include a resin moisture permeable film and a laminate of a polyethylene film and paper. Among these, a polyethylene film, a laminate of a polyethylene film and a nonwoven fabric, and a laminate of a polyethylene film and paper are preferable because they can be easily bonded by heat and can be obtained at low cost.
(3) Other Layers The laminate according to the present invention is not only composed of two layers (A) and (B), or three layers (A), (B) and (C), If necessary, other layers may be laminated in addition to these layers.
2. Structure and action of the laminate according to the present invention The laminate according to the present invention is obtained by laminating the hydrophobic nonwoven fabric (A) and the water absorbent sheet (B). In this case, the laminate is thermally bonded. By using this method, the hydrophobic nonwoven fabric fibers partially melt and impregnate the water absorbent sheet, and the hydrophobic nonwoven fabric thermoplastic resin embracs the hydrophilic fibers of the water absorbent sheet. Will adhere. As a result, the hydrophilic fibers of the water-absorbent sheet are exposed on the surface of the hydrophobic nonwoven layer, or the hydrophilic fibers of the water-absorbent sheet are present near the surface of the hydrophobic nonwoven layer even if not exposed. It is in the state which has a part.
[0013]
Water adhering to the surface of the hydrophobic non-woven fabric layer is absorbed into the water-absorbent sheet by infiltrating from the voids on the surface of the non-woven fabric, or into the water-absorbent sheet fibers present on the surface of the non-woven fabric. By being absorbed directly, it will be absorbed by this laminated body.
There are no particular restrictions on the thickness of the hydrophobic nonwoven fabric (A) and the water absorbent sheet (B) used for lamination, and the hydrophilic fibers of the water absorbent sheet are exposed on the surface of the hydrophobic nonwoven fabric layer as described above. Or what is necessary is just to be able to achieve the state which has the part in which the hydrophilic fiber of a water absorbing sheet exists near the surface of a hydrophobic nonwoven fabric layer.
[0014]
Furthermore, when the layer (C) made of a waterproof material is further laminated on the water absorbent sheet layer side, the thickness of the layer (C) made of the waterproof material is not particularly limited and depends on the purpose. May be selected as appropriate.
3. Method for producing laminate according to the present invention As a method for producing a laminate according to the present invention, as described above, the hydrophobic nonwoven fabric (A) and the water absorbent sheet (B) must be by thermal bonding. It is. The mode is not particularly limited as long as it is based on thermal bonding, but specifically, thermocompression bonding with a heating roll is preferably used. That is, in a method of directly laminating the nonwoven fabric and the water absorbent paper, the nonwoven fabric and the water absorbent paper wound around the rolls are pulled out from the rolls, and both are stacked and laminated by passing between the two heated rolls, It is to wind up. In this method, lamination temperature, the nonwoven fabric in contact with the side of the roll for (hereinafter, "first roll" and that there is called), is a low have temperature Ri by the melting point of the nonwoven material. If the melting point is exceeded, the nonwoven fabric resin may adhere to the heating roll and heat bonding may not be possible, and the nonwoven fabric may be formed into a sheet, resulting in a harder texture or reduced strength and brittleness.
[0015]
On the other hand, if the temperature is too low, the temperature of the bonding surface is low, resulting in insufficient adhesion or adhesion. For example, when an ethylene-α-olefin copolymer spunbonded nonwoven fabric having a melting point of 120 ° C. is used as the nonwoven fabric, the temperature is preferably 100 to 120 ° C. The roll on the side in contact with the water absorbent sheet (hereinafter sometimes referred to as “second roll”) needs to be at a temperature equal to or higher than the melting point of the nonwoven fabric material. If it is less than the melting point of the nonwoven fabric material, the hydrophobic nonwoven fabric (A) and the water absorbent sheet (B) cannot be sufficiently bonded. For example, when an ethylene-α-olefin copolymer spunbonded nonwoven fabric having a melting point of 120 ° C. is used as the nonwoven fabric, the temperature is desirably 120 to 180 ° C.
[0016]
Moreover, there is no restriction | limiting in particular about the pressure and the speed of a roll, What is necessary is just to select suitably by balance with the temperature of a roll. About a pressure, it is chosen in the range of 1-10 kgG / cm < ² > normally.
In the heating roll to be used, the surface thereof may be a lattice shape, a pin shape, a stripe shape, a flat shape, or the like.
[0017]
Furthermore, a method in which the nonwoven fabric is formed and laminated in-line may be used. That is, the water absorbent paper wound around the roll is pulled out of the roll, the nonwoven fabric fibers are dropped on the water absorbent paper to form a web on the water absorbent paper, and this is laminated by passing between two heated rolls, It is to wind up. Also in this case, the temperature, pressure, and speed of the heating roll are the same as in the case where the nonwoven fabric and the water absorbent paper are directly heat laminated.
[0018]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.
〔Evaluation methods〕
(1) Skin irritation evaluation The nonwoven fabric side of the laminate used was applied to the skin of the subject, and after 24 hours, the condition of the applied skin was visually evaluated. The number of test subjects was 10, and the number of persons whose changes such as skin redness and rash were recognized was defined as “number of defects”.
(2) Hydrophilic evaluation A test piece is fixed to a slope with an inclination angle of 45 °, a drop of water is dropped from a height of 2 cm from the test piece, and the length (cm) that has flowed over the test piece until it is absorbed. It was measured. About each test piece, it repeated 10 times, and made the average value the measured value.
[Example 1]
As a hydrophobic nonwoven fabric, an ethylene-1-octene copolymer nonwoven fabric (“Stratec LN2015 (weight per unit: 15 g / m ² , fiber diameter: 20 μm, melting point: 120 ° C.) manufactured by Idemitsu Petrochemical Co., Ltd.) is used, and water absorbent paper is used as a water absorbent sheet. (using Daishowa first manufactured "absorption paper (basis weight 17 g / m ^2)", the first roll temperature 110 ° C., the second roll temperature 140 ° C., a pressure 6kgG / cm ^2, the heat under the conditions of speed of 20 m / min take-off A laminated body was obtained by pressure bonding, and a heating roll having a lattice-like surface was used.
[0019]
As a result, the number of defects in skin irritation evaluation was 0, and the measured value in hydrophilicity evaluation was 4.4 cm.
[Comparative Example 1]
As a hydrophobic nonwoven fabric, an ethylene-1-octene copolymer nonwoven fabric (“Stratec LN2015 (weight per unit: 15 g / m ² ) manufactured by Idemitsu Petrochemical Co., Ltd.)” and a surfactant (“Pepol” manufactured by Toho Chemical Co., Ltd., concentration 2.5) A laminate was produced in the same manner as in Example 1 except that the one coated with (weight%) was used.
[0020]
As a result, the number of defects in skin irritation evaluation was 4, and the measured value in hydrophilicity evaluation was 4.2 cm.
[0021]
【The invention's effect】
According to the present invention, hydrophilicity is imparted to the nonwoven fabric without applying a surfactant or the like and applying hydrophilic treatment, and as a result, a hydrophilic laminated sheet having sufficient water absorption performance can be obtained. .

Claims (1)

In the method for producing a hydrophilic laminated sheet obtained by laminating a hydrophobic nonwoven fabric and water absorbent paper by thermal bonding by passing between two heated embossing rolls,
An embossing roll on the side contacting the hydrophobic nonwoven fabric, while the low have temperature Ri by the melting point of the hydrophobic nonwoven fabric,
A method for producing a hydrophilic laminated sheet, characterized in that the embossing roll on the side in contact with the water-absorbent paper is brought to a temperature equal to or higher than the melting point of the hydrophobic nonwoven fabric.