JP2012187830A - Method for manufacturing liquid absorbent sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a liquid absorbent sheet which prevents the sticking of a resin melt to a needle for forming pores, and can improve productivity.SOLUTION: In the method for manufacturing the liquid absorbent sheet 10 having a hydrophobic layer 11 and a liquid absorbent layer 12 with liquid absorbency, and pores 13 formed at least on the hydrophobic layer 11, the method includes: a layering step of forming a laminate of the hydrophobic layer 11 and the liquid absorbent layer 12; and a pore forming step of forming the pores 13 by thermal perforation from a side of the liquid absorbent layer 12 of the laminate. A heating temperature in the pore forming step is at least the melting point of the thermoplastic resin.

Description

  The present invention relates to a method for producing a liquid-absorbing sheet that is used under a food from which blood or body fluid (hereinafter referred to as drip) such as meat or fish comes out.

  In food departments such as supermarkets, fish, meat, and other foods are dispensed into trays and sold in a state of being wrapped in a transparent film. When taking such a sales form, the food is left on the display shelf for a long time, and the drip tends to accumulate in the tray. The drip that accumulates in the tray not only impairs the appearance but also causes the food to be damaged earlier.

  Conventionally, a liquid-absorbing sheet (hereinafter, used for such a purpose) can quickly absorb the drip by placing it between the tray and the food on the tray on which the food from which the drip comes out is placed. The liquid absorbing sheet is also referred to as a drip sheet). For example, Patent Document 1 discloses a non-woven fabric having antibacterial and water-absorbing properties, a plastic perforated film layer in which a large number of micropores are formed on one surface of the non-woven fabric, and the other surface of the non-woven fabric. A drip sheet comprising a plastic outer film layer that is laminated and disposed to block air flow has been proposed.

  Patent Document 2 proposes a drip sheet in which layers made of a resin film are provided on the front and back surfaces of a liquid absorption layer, and at least a plurality of apertures are formed in the surface layer in contact with the food. .

  In the drip sheet proposed in Patent Documents 1 and 2, a large number of apertures are formed by piercing a heated needle from the film layer side.

JP-A-8-205762 Japanese Patent Laid-Open No. 2002-300848

  However, in the above-described manufacturing method in which the hole is formed by piercing the needle from the film layer side, an attachment made of a part of the resin melted at the tip of the needle while repeating the step of piercing the needle into the film layer. Kimono accumulates. And there existed a problem that a deposit | attachment will re-adhere to the opening part vicinity of a film layer as a foreign material. In order to prevent the reattachment of foreign matter to the film layer, it is necessary to sequentially clean the needle, which has been a factor of reducing the production efficiency of the liquid absorbing sheet.

  Therefore, an object of this invention is to provide the manufacturing method of the liquid absorption sheet which can prevent adhesion of the resin melt to the needle | hook for forming an opening part, and can improve production efficiency.

  The present invention comprises a hydrophobic layer made of a film or a hydrophobic nonwoven fabric composed of a thermoplastic resin, and a liquid absorbing layer composed of a nonwoven fabric having liquid absorbability and laminated on the hydrophobic layer, at least the hydrophobic layer A method for producing a liquid absorbing sheet having a plurality of apertures formed therein, wherein a plurality of apertures are formed by laminating the hydrophobic layer and the liquid absorbing layer, and heating perforation from the liquid absorbing layer side. An opening portion forming step of forming a portion, and the heating temperature in the opening portion forming step relates to a method for producing a liquid-absorbing sheet that is equal to or higher than the melting point of the thermoplastic resin.

  Moreover, it is preferable that the said liquid absorption layer is a nonwoven fabric which consists of a non-thermoplastic fiber.

  In addition, the liquid absorption layer is configured to include a thermoplastic fiber, and the thermoplastic fiber has a melting point higher than that of the thermoplastic resin that configures the hydrophobic layer, and the heating temperature is the same as that of the thermoplastic resin. It is preferable that the melting point is higher than the melting point and lower than the melting point of the thermoplastic fiber.

  Moreover, in the said opening part formation process, it is preferable that a part of nonwoven fabric which comprises the said liquid absorption layer protrudes from the said several opening part to the said hydrophobic layer side.

  Moreover, it is preferable to adhere | attach the said hydrophobic layer and the said liquid absorption layer with the said thermoplastic resin fuse | melted by the heating perforation in a hole part formation process.

  Moreover, it is preferable to further include a second laminating step that is provided after the opening portion forming step and that laminates a water-impermeable third layer on the surface of the liquid absorbing layer where the hydrophobic layer is not disposed.

  Further, the present invention provides a two-layer structure in which a hydrophobic layer made of a thermoplastic resin-made film or a hydrophobic non-woven fabric and a liquid-absorbing layer made of a non-woven fabric having liquid absorbency and laminated on the hydrophobic layer are laminated. A liquid-absorbing sheet having a layer structure, wherein at least a plurality of apertures formed in the hydrophobic layer and a part of the nonwoven fabric constituting the liquid-absorbing layer protrude from the plurality of apertures toward the hydrophobic layer. It is related with the liquid absorption sheet | seat further provided with the protruding fiber part formed in this way.

  Moreover, it is preferable that the plurality of apertures are formed by heating perforation from the liquid absorption layer side, and the heating temperature when forming the apertures is equal to or higher than the melting point of the thermoplastic resin.

  Moreover, it is preferable that the said liquid absorption layer is a nonwoven fabric which consists of a non-thermoplastic fiber.

  In addition, the liquid absorption layer is configured to include thermoplastic fibers, and the thermoplastic fibers have a melting point higher than that of the thermoplastic resin, and the heating temperature is lower than the melting point of the thermoplastic fibers. Is preferred.

  According to the method for producing a liquid-absorbing sheet of the present invention, it is possible to prevent the resin melt from adhering to the piercing needle in the step of forming the opening portion, thereby improving the production efficiency of the liquid-absorbing sheet.

It is a top view of the liquid absorption sheet which concerns on embodiment of this invention. It is a side view of the liquid absorption sheet which concerns on embodiment of this invention. It is a partial expanded sectional view of the cross section in the AA line of FIG. It is the figure which showed typically the process of the aperture part formation process which is 1 process of the manufacturing method of the liquid absorption sheet which concerns on the embodiment of this invention. It is the enlarged photograph which image | photographed the aperture part of the liquid absorption sheet which concerns on embodiment of this invention from the hydrophobic layer side.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the structure of a liquid absorption sheet is demonstrated, and the manufacturing method of a liquid absorption sheet is demonstrated after that. The liquid-absorbing sheet of the present invention can be used particularly suitably as a drip sheet that absorbs drip from food, and can also be used for various other purposes for absorbing and holding liquid. Here, the case where it uses as a drip sheet | seat is demonstrated as a preferable example of the embodiment and embodiment of this invention. FIG. 1 is a plan view of a liquid absorbent sheet according to an embodiment of the present invention, and FIG. 2 is a side view of the liquid absorbent sheet 10. 3 is a partially enlarged schematic view of a cross section taken along the line AA of FIG. FIG. 4 is a view schematically showing a process of an opening portion forming step which is one step of the method for manufacturing the liquid absorbent sheet according to the embodiment of the present invention. FIG. 5 is an enlarged photograph of the aperture.

<Structure of liquid absorption sheet>
As shown in FIGS. 1 and 2, the liquid absorbent sheet 10 of the present embodiment includes a hydrophobic layer 11, a liquid absorbent layer 12 that is stacked on the hydrophobic layer 11, and a plurality of layers formed at least on the hydrophobic layer 11. The opening part 13 and the protruding fiber part 14 formed to protrude from the plurality of opening parts 13 toward the hydrophobic layer 11 are provided.

  The size and shape of the liquid absorbent sheet 10 in plan view are not particularly limited. Depending on the purpose of use, it can be suitably formed into a preferred size and shape or cut.

  The hydrophobic layer 11 constitutes the upper surface of the liquid absorbing sheet 10. The upper surface of the hydrophobic layer 11 is in contact with the bottom surface of the food placed on the liquid absorbing sheet 10. The hydrophobic layer 11 is composed of a film composed of a thermoplastic resin or a hydrophobic nonwoven fabric composed of a thermoplastic assembled resin. The type of thermoplastic resin is not particularly limited, but low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), polypropylene (PP), polyethylene terephthalate ( PET), ethylene / vinyl acetate copolymer (EVA) and the like are preferable. A resin film in which these resins are formed in a single layer or multiple layers can be suitably used as the material of the hydrophobic layer 11. Moreover, as a hydrophobic nonwoven fabric which consists of thermoplastic resins, the SMS nonwoven fabric made from PP, the thermal bond nonwoven fabric made from PP, etc. are preferable, for example. In this way, the material constituting the hydrophobic layer is made of a thermoplastic resin film or non-woven fabric, so that the aperture 13 can be easily and reliably formed by the heated puncture needle 20 in the aperture formation process described later. can do. Among the above materials, it is particularly preferable to use a polyethylene resin film such as HDPE from the viewpoint of softness and cost.

  It is preferable to mix a surfactant into each material of the hydrophobic layer 11. The amount of the surfactant to be mixed is preferably such an amount that the surfactant is contained at a ratio of 1 to 3% by mass with respect to the hydrophobic layer 11. When the surfactant content is less than 1% by mass, it is not possible to suppress the generation of undesired static electricity during the cutting process, and when the surfactant content exceeds 3%, the hydrophobic layer 11 is absorbed. The water surface of the sheet becomes so strong that the water repellent function is insufficient.

  Surfactants include nonionic polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, glycerin fatty acid ester, sorbitan fatty acid ester, anionic alkyl sulfonate, alkyl benzene, etc. Sulfonate, alkyl sulfate, alkyl phosphate, etc. Cationic quaternary ammonium chloride, quaternary ammonium sulfate, quaternary ammonium nitrate, or amphoteric alkyl betaine type, alkyl imidazoline type, alkyl alanine type, etc. Can be used.

  The thickness of the hydrophobic layer 11 is 1 to 70 μm, preferably 30 to 70 μm. If the thickness is less than 1 μm, it is not preferable because it lacks the durability desired as a drip sheet. If the thickness is in the range of 30 μm or more and 70 μm or less, the durability as a drip sheet is sufficient, and the opening portion It is excellent in workability when forming. If it exceeds 70 μm, the processability is lowered, the material is wasted and disadvantageous in terms of cost.

  The liquid absorption layer 12 is laminated on the lower surface side of the hydrophobic layer 11. The liquid absorption layer 12 absorbs and holds the drip that has exuded from food or the like. As a material constituting the liquid absorbing layer 12, a nonwoven fabric such as an airlaid nonwoven fabric or a thermal bond nonwoven fabric, paper, urethane, or a plant-derived highly liquid-absorbing polymer can be used. As the fibers constituting the nonwoven fabric, natural fibers such as pulp, manila hemp, kenaf and cotton, plant-based regenerated fibers such as rayon, or synthetic fibers such as polyethylene terephthalate (PET) can be used. As the pulp, wood-based pulp such as NBKP made from coniferous trees, or non-wood pulp such as kenaf and manila hemp can be used. Among these, it is particularly preferable to use a nonwoven fabric mainly composed of pulp from the viewpoint of liquid absorbability.

The basis weight and thickness of the nonwoven fabric or the like constituting the liquid absorbing layer 12 are determined so that the drip oozed from the food can be sufficiently absorbed. Speaking of an airlaid nonwoven fabric made of pulp, the basis weight is preferably 10 to 120 g / m ² , and the thickness is preferably about 0.3 to 3 mm, and more preferably about 0.5 to 2 mm.

  In addition, when the nonwoven fabric used as the material of the liquid absorption layer 12 includes a thermoplastic fiber, the thermoplastic fiber having a higher melting point than the thermoplastic resin constituting the hydrophobic layer 11 is used. In order to easily adjust the temperature of the punch needle 20, the temperature difference between the melting points of the thermoplastic fiber and the thermoplastic resin is preferably 50 ° C. or more.

As shown in FIGS. 1 and 3, the plurality of apertures 13 are formed through the hydrophobic layer 11 and the liquid absorption layer 12. However, it is sufficient that the opening 13 penetrates at least from the surface of the hydrophobic layer 11 to the interface where the hydrophobic layer 11 and the liquid absorbing layer 12 are in contact as a drip introduction path, and the hydrophobic layer 11 and the liquid absorbing layer 12 are not necessarily required. It does not have to penetrate. The plurality of apertures 13 permeate the drip that oozes out from the food and stays on the upper surface of the hydrophobic layer 11 to the liquid absorbing layer 12 side. The density of the apertures 13 is preferably 20 or more, more preferably 200 or more per 1 cm ² . By arranging the numerous apertures 13 evenly, the food comes in contact with the air without unevenness. The opening 13 is preferably formed over the entire surface of the hydrophobic layer 11 at the above density. However, the opening 13 may be provided only in a partial range of the hydrophobic layer 11, and the position where the food that exudes the drip is placed may be limited to the partial range.

  The aperture diameter of the aperture 13 is 5.0 mm or less, more preferably about 0.1 to 2.0 mm. If the aperture diameter is larger than the above range, drip absorbed by the liquid absorbing layer 12 from the aperture portion 13 will be visually recognized. On the other hand, if the aperture diameter is smaller than the above range, the drip absorbency to the liquid absorbing layer 12 through the aperture portion 13 is lowered, and it is not preferable because the drip sheet cannot exhibit sufficient absorbency.

  As shown in FIG. 3, the protruding fiber portion 14 is formed on the hydrophobic layer 11 side in the peripheral portion of the plurality of apertures 13. The protruding fiber portion 14 is formed such that a part of the nonwoven fabric constituting the liquid absorbing layer 12 is inserted through the aperture 13 and protrudes toward the hydrophobic layer 11 side. As a result of the drip around the aperture 13 being absorbed by the protruding fiber portion 14, the drip staying on the surface of the hydrophobic layer 11 is introduced into the aperture 13 more rapidly.

  According to the liquid absorbing sheet 10 having the above-described configuration, the drip is quickly absorbed by the liquid absorbing layer 12 through the opening 13 of the hydrophobic layer 11. Further, at that time, the protruding fiber portion 14 triggers liquid introduction and further promotes liquid absorption. In this case, the drip does not remain on the surface of the hydrophobic layer 11, and the food placed on the liquid absorbent sheet 10 is separated from the drip, and the food damage caused by the drip is progressed. Can be prevented.

<Method for producing liquid absorbing sheet>
Next, a preferred first embodiment of the method for producing a liquid-absorbing sheet of the present invention will be described with reference to the drawings. FIG. 4 is a diagram schematically showing an opening process of an opening portion forming step, which is a characteristic step in the method for manufacturing a liquid absorbent sheet according to an embodiment of the present invention.

  The manufacturing method of the liquid absorbent sheet 10 in the present embodiment includes a lamination process in which the hydrophobic layer 11 and the liquid absorption layer 12 are laminated, and liquid absorption in a laminate including the hydrophobic layer 11 and the liquid absorption layer 12 laminated in the lamination process. From the layer 12 side, a heated punching needle 20 is pierced to form a plurality of apertures 13 and a cutting step of cutting the laminate formed with the apertures 13 into a predetermined product size. It consists of.

[Lamination process]
The laminating step is a step of integrating the hydrophobic layer 11 and the liquid absorbing layer 12 to form a laminate composed of the hydrophobic layer 11 and the liquid absorbing layer 12. In the present embodiment, the hydrophobic layer 11 and the liquid absorbing layer 12 are bonded to each other by a hot melt adhesive at bonding portions (not shown) scattered over the entire surface of the liquid absorbing layer 12. Further, as another method for forming a laminate by integrating the hydrophobic layer 11 and the liquid absorbing layer 12, a method of forming a resin film by melt-extruding the material resin of the hydrophobic layer 11 on the surface of the liquid absorbing layer 12 is used. It is also possible.

As described above, the liquid-absorbing layer 12 can be made of non-woven fabric, paper, urethane, or a plant-derived high-liquid-absorbing polymer. The airlaid nonwoven fabric to be used can be used particularly preferably. The basis weight of the air laid nonwoven fabric is preferably 10 to 120 g / m ² . Moreover, it is preferable that the thickness of an air-laid nonwoven fabric is about 0.3-3 mm, and it is more preferable that it is about 0.5-2 mm.

  When a thermoplastic resin such as HDPE is used as the material constituting the hydrophobic layer 11, the synthetic resin is formed into a film by the following method. First, a surfactant is mixed in the synthetic resin. As described above, the amount of the surfactant to be mixed is preferably such an amount that the surfactant is contained in a proportion of 1 to 3% by mass with respect to the hydrophobic layer 11. Further, as described above, a nonionic or anionic alkyl sulfonate, cationic or amphoteric surfactant can be used.

  A synthetic resin containing a surfactant at the above ratio is formed into a film by an extrusion molding method or the like. The formed film may be a single layer to form the hydrophobic layer 11, or may be the hydrophobic layer 11 in a multilayer state in which a plurality of films are laminated. The thickness of the hydrophobic layer 11 thus manufactured is preferably 1 to 70 μm, and more preferably 30 to 70 μm.

Further, as a material constituting the hydrophobic layer 11, for example, a thermoplastic hydrophobic nonwoven fabric such as an SMS nonwoven fabric made of polypropylene may be used. The thermoplastic hydrophobic nonwoven fabric used for the hydrophobic layer 11 preferably has a basis weight of 10 to 50 g / m ² mainly from the viewpoint of processability and material cost.

[Open hole forming step]
As shown in FIGS. 4 (a) to 4 (d), in the opening portion forming step, the heated piercing needle 20 is pierced into the laminated body integrated in the laminating step, and the liquid is removed from the hydrophobic layer 11. This is a step of forming an opening 13 that penetrates to the absorption layer 12.

  In the present embodiment, the opening 13 is formed using a roller (not shown; hereinafter simply referred to as a roller) provided with a large number of perforating needles 20 on the outer periphery. Further, this roller has a function of heating the punch needle 20 to a predetermined temperature. While rotating such a roller and winding up the laminated body formed in the laminating process with the roller, the material is passed directly below. Immediately below the roller, a number of heated piercing needles 20 are continuously pierced into the laminate and pulled out. As such, a large number of apertures 13 can be formed efficiently.

  The process for forming the opening 13 will be described in more detail with reference to FIG. In this process, the piercing needle 20 is heated to an appropriate temperature in advance. The heating temperature of the piercing needle 20 is set to a temperature equal to or higher than the melting point of the thermoplastic resin constituting the hydrophobic layer, and to a temperature lower than the melting point when the liquid absorbing layer 12 contains thermoplastic fibers.

  Next, as shown in FIG. 4A, the liquid absorbent layer 12 side surface of the laminate formed in the laminating step is passed directly under the roller in a direction to face the perforation needle 20.

  Next, as shown in FIG. 4B, the piercing needle 20 pierced by the liquid absorbing layer 12 pushes a part of the nonwoven fabric constituting the liquid absorbing layer 12 toward the hydrophobic layer 11, and then absorbs the liquid absorbing layer 12. It penetrates inside. Here, since the temperature of the perforation needle 20 is lower than the temperature of the thermoplastic fiber contained in the liquid absorption layer 12, the thermoplastic fiber contained in the liquid absorption layer 12 does not melt.

  Further, as shown in FIG. 4C, the piercing needle 20 is heated to a temperature higher than that of the thermoplastic resin constituting the hydrophobic layer 11. Thereby, the piercing needle 20 easily penetrates the hydrophobic layer 11 and is exposed to the outer surface side of the hydrophobic layer 11 while melting the thermoplastic resin or fiber constituting the hydrophobic layer 11. At this time, a part of the nonwoven fabric constituting the liquid absorbing layer 12 is dragged by the perforating needle 20 and protrudes to the surface of the hydrophobic layer 11.

Then, as shown in FIG. 4 (d), an opening 13 is formed in the trace where the piercing needle 20 is pulled out from the hydrophobic layer 11 and the liquid absorbing layer 12. And the protruding fiber part 14 which consists of a nonwoven fabric which has a liquid absorptivity is formed in the hydrophobic layer 11 side of the peripheral part of the opening part 13.
In the opening portion forming step described above, when penetrating the hydrophobic layer 11, the thermoplastic resin constituting the hydrophobic layer 11 is melted to the perforation needle 20, and the molten thermoplastic resin is slightly adhered. However, the piercing needle 20 passes through the liquid absorbing layer 12 again when it is pulled out from the state of penetrating the hydrophobic layer 11. Therefore, the thermoplastic resin adhering to the piercing needle 20 is removed by the nonwoven fabric constituting the liquid absorbing layer 12 when the piercing needle 20 is pulled out from the liquid absorbing sheet 10.

[Cutting process]
This step is a step of cutting the laminated body that has undergone the laminating step and the aperture forming step into a product size to obtain the liquid absorbing sheet 10. This cutting step includes a cutting preparation step of pulling out the laminate produced in the lamination step while applying an appropriate tension, a first cutting step of cutting along the length direction of the sheet by a first cutting cutter, It consists of the 2nd cutting process cut | judged in the width direction of a sheet | seat with a 2 cutting cutter.

  In the first cutting process and the second cutting process, the laminate cut into an appropriate size becomes the liquid absorbent sheet 10. The cutting process may be a cutting method that can finally be set to an appropriate size as a product, and is not limited to a method that passes through each of the above processes.

  According to the manufacturing method and liquid absorption sheet of the above liquid absorption sheet, there exist the following effects.

  (1) A conventional liquid-absorbing sheet in which an aperture is formed by piercing a piercing needle heated at a temperature equal to or higher than the melting point of the thermoplastic resin from a hydrophobic layer side made of a film made of thermoplastic resin or a hydrophobic nonwoven fabric. In this manufacturing method, while the step of piercing the piercing needle is repeated, an adhering matter made of a part of the molten resin is accumulated at the tip portion. Therefore, in the method for producing a liquid absorbent sheet according to the present invention, the opening 13 is formed by perforating at a heating temperature equal to or higher than the melting point of the thermoplastic resin from the liquid absorbent layer 12 side constituted by a nonwoven fabric. It was. As a result, when the piercing needle 20 is finally pulled out, the tip of the piercing needle 20 slips through the liquid absorbing layer 12 while being in contact with the fibers constituting the liquid absorbing layer 12, so that the resin melt to the piercing needle 20 is in the process. This prevents the accumulation of deposits. Therefore, it is possible to reduce the burden associated with cleaning the perforating needle 20 and increase productivity.

  (2) Further, when the liquid absorbing layer 12 is a non-woven fabric made of non-thermoplastic fibers, it is difficult for the resin melt to adhere in the initial stage of the formation process of the apertures 13, and a trace amount in the subsequent stage. Even if the resin melt adheres, the tip of the piercing needle 20 slips through the liquid absorbing layer 12 in contact with the fibers constituting the liquid absorbing layer 12 as in (1). Objects can be removed in the process to prevent accumulation of deposits. Therefore, it is possible to further reduce the burden associated with cleaning the perforating needle 20 and increase the productivity.

  (3) Moreover, when the liquid absorption layer 12 is comprised including a thermoplastic fiber, it decided to form the opening part 13 with the heating temperature less than melting | fusing point of the thermoplastic fiber which comprises a liquid absorption layer. This makes it difficult for the resin melt to adhere in the initial stage of the formation process of the aperture 13, and even if a small amount of resin melt adheres in the subsequent stage, the tip of the punch needle 20 is the same as in (1). Since the portion slips through the liquid absorbing layer 12 while contacting the fibers constituting the liquid absorbing layer 12, the resin melt on the perforating needle 20 is removed in the process, and accumulation of deposits can be prevented. Therefore, it is possible to reduce the burden associated with cleaning the perforating needle 20 and increase productivity.

  (4) According to the method for producing a liquid-absorbing sheet of the present invention, in the opening portion forming step, a part of the nonwoven fabric constituting the liquid-absorbing layer 12 is pushed up from the plurality of opening portions 13 by the perforating needles 20, and the hydrophobic layer The protruding fiber portion 14 is formed protruding to the 11 side. The protruding fiber portion 14 triggers drip absorption to the liquid absorbing layer 12 through the opening 13. Therefore, the liquid-absorbing sheet 10 having excellent absorption performance can be manufactured by a manufacturing method with high productivity.

  (7) The liquid absorbent sheet 10 includes a hydrophobic layer 11 made of a thermoplastic resin or a hydrophobic nonwoven fabric, and a liquid absorbent layer 12 made of a liquid absorbent nonwoven fabric and laminated on the hydrophobic layer. And a plurality of apertures 13 formed in at least the hydrophobic layer 11 and a part of the nonwoven fabric constituting the liquid absorbing layer 12 is the plurality And a protruding fiber portion 14 formed to protrude from the aperture 13 to the hydrophobic layer 11 side. The protruding fiber portion 14 triggers drip absorption to the liquid absorbing layer 12 through the opening 13. Therefore, the drip can be absorbed more quickly than the conventional liquid absorbing sheet.

  (8) The opening 13 is formed by heating perforation from the liquid absorption layer 12 side, and the heating temperature when forming the opening is set to be equal to or higher than the melting point of the thermoplastic resin. Thereby, since the perforation needle 20 pushes up the fiber which comprises the liquid absorption layer 12, and forms the protruding fiber part 14, absorption performance improves. Further, it is possible to prevent the molten resin from adhering to the piercing needle 20 in the opening portion forming step and increase the productivity.

  (9) The liquid absorption layer 12 was a non-woven fabric made of non-thermoplastic fibers. Thereby, adhesion of the molten resin to the piercing needle 20 in the opening portion forming step can be prevented and productivity can be improved.

  (10) The liquid absorbing layer 12 includes a thermoplastic fiber, and the thermoplastic fiber has a higher melting point than that of the thermoplastic resin, and the heating temperature when forming the hole opening portion is the same as that of the thermoplastic fiber. Lower than the melting point. Thereby, adhesion of the molten resin to the piercing needle 20 in the opening portion forming step can be prevented and productivity can be improved.

  Next, the 2nd embodiment of the manufacturing method of the liquid absorption sheet of this invention is demonstrated. In the manufacturing method of the liquid absorption sheet of the second embodiment, the method of integrating the hydrophobic layer 11 and the liquid absorption layer 12 is different from that of the first embodiment. In the second embodiment, in the opening portion forming step, the hydrophobic layer 11 and the liquid absorbing layer 12 are bonded by the adhesive force of the thermoplastic resin constituting the hydrophobic layer melted by the heat of the piercing needle 20. . According to the manufacturing method of the liquid-absorbing sheet of the second embodiment, the following effects can be obtained.

  (5) In the opening portion forming step, the hydrophobic layer 11 and the liquid absorbing layer 12 are bonded to each other by the thermoplastic resin melted by heat drilling. Thereby, since formation of the opening part 13 and adhesion | attachment of two layers can be performed by one process, productivity of the liquid absorption sheet 10 can be improved.

  Furthermore, the 3rd embodiment of the manufacturing method of the liquid absorption sheet of this invention is demonstrated. The manufacturing method of the liquid-absorbing sheet of the third embodiment is different from the first embodiment and the second embodiment in that it includes a second lamination step.

  The second stacking step is provided after the opening portion forming step. In the second lamination step, a water-impermeable third layer is laminated on the laminate of the liquid absorption layer 12 and the hydrophobic layer 11 in which the plurality of opening portions 13 are formed in the opening portion forming step. More specifically, in the second stacking step, the third layer is stacked on the surface of the liquid absorbent layer 12 of the stacked body where the hydrophobic layer 11 is not disposed. According to the manufacturing method of the liquid-absorbing sheet of the third embodiment, the following effects can be obtained.

  (6) After the opening portion forming step, the non-water-permeable third layer is laminated on one surface of the liquid absorbing layer 12 where the hydrophobic layer 11 is not laminated. Thereby, it is possible to manufacture a liquid-absorbing sheet having a three-layer structure that can prevent the resin melt from adhering to the piercing needle 20 and prevent leakage of the drip on the back surface of the sheet as in the above-described manufacturing methods. it can.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited by these Examples.

<Examples 1-5, Comparative Examples 1 and 2>
Using the materials described below, liquid absorbent sheets having the configurations shown in Table 1 below were produced, and liquid absorbent sheets of Examples 1 to 5 and Comparative Examples 1 and 2, respectively. About the liquid absorption sheet | seat of Examples 1-5 and the comparative example 1, the laminated body for liquid absorption sheets was manufactured by laminating | stacking and adhering the hydrophobic layer and liquid absorption layer which consist of the following each material sequentially. For Comparative Example 2, a laminate for a liquid absorbent sheet was produced by further laminating and bonding a third layer disposed on the surface of the liquid absorbent layer opposite to the hydrophobic layer side. Adhesion between the respective layers was performed by a method of adhering with a hot melt adhesive of ² g / m ² . The width of the laminate for the liquid absorbent sheet was 1000 mm and the length was 1000 m.

[Hydrophobic layer]
The hydrophobic layer and the third layer were formed of the following materials (material name: thickness or basis weight).
High-density polyethylene film: 30 μm (hereinafter referred to as HDPE)
SMS nonwoven fabric: 20 g / m ² per unit area (hereinafter referred to as SMS)
Spunbond nonwoven fabric: 20 g / m ² per unit area (hereinafter referred to as SB)
The melting point of HDPE is about 130 to 137 ° C., and the melting point of polypropylene constituting SMS and SB is about 170 ° C.

[Liquid absorption layer]
The liquid absorbing layer was formed from the following materials (material name: composition: basis weight).
Airlaid nonwoven fabric: NBKP 100% pulp: basis weight 50 g / m ² (hereinafter referred to as nonwoven fabric 1)
Airlaid nonwoven fabric: NBKP 50%, PET 50% pulp: basis weight 50 g / m ² (hereinafter referred to as nonwoven fabric 2)
Wet crepe paper: NBKP 100% pulp: 50 g / m ² per unit area (hereinafter referred to as paper 1)
NBKP is a non-thermoplastic fiber, and the melting point of PET is about 260 to 264 ° C.

<Open hole formation test>
Openings were formed using a roller in which a large number of perforating needles were provided on the outer periphery of the laminates for liquid-absorbing sheets of Examples 1 to 5 and Comparative Examples 1 and 2. During the operation of forming the opening, the perforation needle was operated while being heated to 200 ° C. The apertures were formed on the entire surface of the laminate at a density of 15 per cm ² with an aperture diameter of 0.5 mm. For Examples 1 to 5, an aperture was formed by projecting a piercing needle from the liquid absorbing layer side, Comparative Example 1 from the hydrophobic layer side, and Comparative Example 2 from the third layer side. When the step of forming the opening portion over 1000 m was completed, the presence or absence of adhesion of the molten resin around the opening portion was examined. Moreover, it was investigated whether the protruding fiber part was formed in the surface by the side of a hydrophobic layer. The results are shown in Table 1 and FIG.

<Liquid absorbency measurement test>
The laminates for the liquid absorbent sheets of Examples 1 to 5 and Comparative Examples 1 and 2 were cut into a size of 65 mm × 80 mm to obtain liquid absorbent sheets of Examples 1 to 5 and Comparative Examples 1 and 2. To these liquid-absorbing sheets, dripping the raw red of the following composition at a rate of 1.0 ml / 3 seconds from 10 mm above the surface of the hydrophobic layer, and measure the time until the dropped liquid is absorbed from the sample surface. Thus, the liquid absorbency was evaluated. The results are shown in Table 1.
Raw food red: 1 L NaCl aqueous solution (concentration 0.9%), Yellow No. 5 1.63 g, Red No. 102 8.5 g, Red No. 2 2 g

  FIG. 5 is an enlarged photograph of the aperture portion of Example 1 taken from the hydrophobic layer side. From FIG. 5, the manufacturing method according to the present invention allows the aperture portion to be formed on the hydrophobic layer side of the peripheral portion. It can be seen that protruding fiber portions are formed.

  From Table 1, it can be seen that adhesion of the melt to the perforation needle can be prevented only when the perforation needle is pierced from the liquid absorption layer side made of nonwoven fabric or paper. Moreover, it turns out that liquid absorption improves with the protruding fiber part formed in connection with opening part formation.

DESCRIPTION OF SYMBOLS 10 Liquid absorption sheet 11 Hydrophobic layer 12 Liquid absorption layer 13 Opening part 14 Protruding fiber part 20 Perforated needle

Claims (10)

A hydrophobic layer made of a thermoplastic resin film or a hydrophobic nonwoven fabric, and a liquid absorbing layer composed of a liquid absorbent nonwoven fabric and laminated on the hydrophobic layer, and at least a plurality of openings are formed in the hydrophobic layer. A method for producing a liquid-absorbing sheet in which holes are formed,
A laminating step of laminating the hydrophobic layer and the liquid absorbing layer;
An opening part forming step of forming a plurality of opening parts by heating perforation from the liquid absorption layer side,
The method for producing a liquid-absorbing sheet, wherein a heating temperature in the opening portion forming step is equal to or higher than a melting point of the thermoplastic resin. It is a manufacturing method of the liquid absorption sheet according to claim 1,
The said liquid absorption layer is a manufacturing method of the liquid absorption sheet which is a nonwoven fabric which consists of non-thermoplastic fibers. It is a manufacturing method of the liquid absorption sheet according to claim 1,
The liquid absorption layer is configured to include a thermoplastic fiber, and the thermoplastic fiber has a higher melting point than the thermoplastic resin constituting the hydrophobic layer,
The method for producing a liquid-absorbing sheet, wherein the heating temperature is not lower than the melting point of the thermoplastic resin and lower than the melting point of the thermoplastic fiber.   4. The liquid absorbent sheet according to claim 1, wherein in the opening portion forming step, a part of the nonwoven fabric constituting the liquid absorption layer is protruded from the plurality of opening portions toward the hydrophobic layer. Method.   The manufacturing method of the liquid absorption sheet in any one of Claim 1 to 4 which adhere | attaches the said hydrophobic layer and the said liquid absorption layer with the said thermoplastic resin fuse | melted by the heat drilling in the said opening part formation process.   6. The method according to claim 1, further comprising a second laminating step that is provided after the opening portion forming step and that laminates a water-impermeable third layer on a surface of the liquid absorbing layer where the hydrophobic layer is not disposed. The manufacturing method of the liquid absorption sheet in any one of. A liquid-absorbing sheet having a two-layer structure in which a hydrophobic layer made of a thermoplastic resin-made film or a hydrophobic nonwoven fabric and a liquid-absorbing layer composed of a liquid-absorbing nonwoven fabric and laminated on the hydrophobic layer are laminated. Because
A plurality of apertures formed in at least the hydrophobic layer;
A liquid-absorbing sheet, further comprising: a protruding fiber part formed by protruding a part of the nonwoven fabric constituting the liquid-absorbing layer from the plurality of apertures toward the hydrophobic layer. The plurality of apertures are formed by heat drilling from the liquid absorption layer side,
The liquid-absorbing sheet according to claim 7, wherein a heating temperature when forming the opening is equal to or higher than a melting point of the thermoplastic resin.   The liquid absorption sheet according to claim 8, wherein the liquid absorption layer is a nonwoven fabric made of non-thermoplastic fibers. The liquid absorption layer is configured to include a thermoplastic fiber, and the thermoplastic fiber has a higher melting point than the thermoplastic resin,
The liquid absorption sheet according to claim 8, wherein the heating temperature is lower than the melting point of the thermoplastic fiber.