JP2020056119A - Air-laid nonwoven fabric and method for producing the same - Google Patents

Abstract

To provide an air-laid nonwoven fabric having an uneven shape capable of enhancing a filtration performance.SOLUTION: The air-laid nonwoven fabric comprises a plurality of valley faces (3) and raised faces (4) which are provided alternately to be adjacent to each other on one main surface (7a) of a sheet body (7), a recess (1) having the valley face (3) and constituting the sheet body (7), and projections (2) having the raised faces (4) and constituting the sheet body (7) integrally with the recess (1). The raised face (4) has an inclined face (4a) formed between a center of the raised face (4) and the valley face (3), and raised fibers (5) in which staple fibers constituting the sheet body (7) are projected outwardly from the inclined face (4a). Therefore, filtration at the inclined face is enhanced and a uniform filtration is realized on a whole surface of the uneven shape.SELECTED DRAWING: Figure 2

Description

  The present invention provides (1) sanitary articles, disposable diapers, and other absorbent articles, (2) personal wipers, objective wipers, (3) drip absorbent sheets (fresh food rugs), and (4) packaging materials having high air permeability. , Cushioning material, (5) adsorptive sheet for gas adsorption, volatilizer used for fragrance, (6) filter, drainer bag, tea pack, coffee filter, (7) lye removing sheet And a method for producing the same. In particular, the present invention relates to an airlaid nonwoven fabric for a gas or liquid filter and a method for producing the same.

  An absorbent article that absorbs liquid discharged from the human body generally includes a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorber between the top sheet and the back sheet. Absorbent articles, such as disposable disposable diapers and sanitary napkins, are required to be capable of absorbing and retaining as much as possible urine, menstrual blood, waste or the like discharged from the human body without side leakage as quickly as possible, and to be thin and light in performance.

  In order to satisfy the performance, it is indispensable to improve the diffusibility and the rapid liquid transport in the process in which the liquid discharged from the wearer passes through the top sheet and is absorbed and held in the absorbent layer. In a general absorbent article, the discharged material repeatedly drops or flows into substantially the same portion of the top sheet. For this reason, the absorption concentrates on a certain portion of the absorption layer, and the absorption is easily saturated. Further, since the dropped liquid has substantially the same aspect ratio, it saturates in the horizontal direction before diffusing in the entire longitudinal direction. Even when only a part of the absorbing layer is used, it is easy for the top sheet to leak laterally. As a result, the absorption amount cannot be secured unless the absorbing layer is made thicker and wider.

  In order to avoid a certain concentration of absorption, Patent Document 1 proposes a liquid diffusion sheet having a plurality of linear (streak-shaped) high-density regions by embossing an air-laid nonwoven fabric made of heat-fused fibers and pulp. I do. The liquid diffusion sheet can improve rapid liquid permeation and diffusion, especially in the form of vertical stripes to prevent lateral leakage at longitudinal edges. However, due to local densification, the sheet is hard and uncomfortable.

  In Patent Literature 2, a pattern is applied to a mat forming wheel that forms a fibrous web, and the formed convex web is shaved to form a fibrous web separator, which is used for an absorbent article such as a sanitary napkin. However, the fibrous web has a very thin cut portion or a void, and has low strength and is difficult to handle.

  Patent Literature 3 proposes a method of forming a fibrous web used for an absorbent article by an air laid method or the like using a fluid-permeable fabric having an uneven pattern. The fibrous web is provided with a concavo-convex pattern on both sides, but there is no description of quality features and effects. In addition, the fibrous web of Patent Document 3 has irregularities on both surfaces, and irregularities also exist on the surface opposite to the side that comes into contact with the skin, so that liquid transfer to the absorbent layer is slow.

  In Patent Document 4, when manufacturing an air-laid nonwoven fabric, projections made of synthetic resin are provided on a fiber collecting net, and short fibers are laminated thereon. Is obtained. However, the convex portion of the airlaid nonwoven fabric does not have a top portion, but necessarily has a flat upper surface of the convex portion and a concave inclined surface. Since the flat upper surface of the convex portion has a relatively large area, the portion in contact with the skin of the human body is large, causing discomfort, and there is a problem that menstrual blood held by the nonwoven fabric sheet directly touches the human body. Further, Patent Literature 4 intends to use an absorbent material, a drip absorber, and a wiper, but does not describe a filter material application such as oil mist removal.

  On the other hand, when manufacturing a nonwoven fabric sheet, the diameter, type, and fiber length of the short fibers can be freely selected according to the application, and a nonwoven fabric sheet having a specific sheet thickness, density, and porosity can be manufactured. In addition, the nonwoven fabric sheet is used as a filter material because it is excellent in flexibility and processability, does not denature, is inexpensive and lightweight, has good transportation efficiency, is nontoxic and has high safety. For example, as gas filters, filters for air purifiers and air conditioners that capture suspended matter and purify indoor air, filters for air conditioning equipment that removes fine dust in sterile spaces such as clean rooms, and dust masks Filter, a filter for dust collection or a vacuum cleaner for catching dust, a filter for a ventilation fan for catching oil mist flying in the air by atomizing oil used in home kitchens, kitchens and factories.

  Patent Document 5 is a nonwoven fabric of a multilayer fiber structure, in which a concave portion is formed by embossing the surface by thermocompression bonding, an upper opening portion is larger than a bottom portion, and an angle between a tangent line contacting a side surface of the concave portion and the bottom portion is formed. A filter medium that is 140-170 ° is disclosed. The concave portion is formed by thermocompression bonding of a spunbonded nonwoven fabric with an embossing roll provided with a large number of truncated cone-shaped convex portions. It has an inclined surface.

  FIG. 14 shows a partial cross-sectional shape of the filter medium 60 of Patent Document 5. The filter medium 60 includes a concave portion 51 having a large number of concave surfaces 53 on one main surface, and a convex portion 52 having a large number of convex surfaces 54 adjacent to the concave surface 53, and the convex surface 54 has an inclined surface 54a. However, the filter medium 60 formed by thermocompression bonding has a high fiber density as a whole, and in particular, the fiber density of the concave portion 51 is much higher than that of the convex portion 52 due to embossing. In addition, the temperature of the surface of the filter medium directly hit by the heating roll is higher than that of the inside, and the melting ratio of the surface fibers is large and the closing rate of the surface voids is high. Therefore, as shown in FIG. 15, the trapped matter 59 easily accumulates on the surface on which the fluid has flowed, and the pressure loss increases early.

  In addition, since the compressed surface of the filter medium 60 is smooth and has no fiber protrusion or fluff, the fluid flows 58a without resistance on the inclined surface 54a, and the amount of filtration on the concave surface 53 is smaller than the amount of filtration on the inclined surface 54a. It is extremely large, and a large amount of collected matter 59 accumulates at the bottom of the concave surface 53 as shown in FIG. In addition, floating substances such as dust, dust, and hair in the fluid to be processed are not easily caught. Furthermore, since the filter medium 60 formed by compression contains high-density fibers, it is difficult to manually cut the filter medium 60 into a size suitable for the application, and it is necessary to apply a ruler to the filter medium 60 and cut using scissors, a cutter, or the like. .

  In addition, the nonwoven fabric sheet is also used for liquid filters such as beverages, liquid foods, seasonings, purified water, sewage, industrial drainage, etc., household water purifiers, tea packs, and the like. Patent Document 6 shows an embossed non-woven coffee drip filter. The embossed rolls having irregularities on the surface disperse and form the embossed portions almost uniformly over the entire nonwoven fabric, thereby imparting strength to the nonwoven fabric. However, in the present filter, as in Patent Document 5, since the filter surface is compressed by embossing, clogging is likely to occur, and pressure rises early. In particular, a large amount of trapped matter accumulates on the bottom surface of the planar concave portion.

  An airlaid nonwoven fabric is known as a nonwoven fabric having a high porosity on the surface without being subjected to pressure embossing. The airlaid nonwoven fabric is formed by laminating heat-adhesive fibers on a wire by gravity or suction and heating to form a sheet. Patent Literature 7 shows an air filter in which an air-laid nonwoven fabric layer is provided on one side surface of a base nonwoven fabric having a plurality of holes formed over the entire plane. However, Patent Document 7 has a small filtration area because the filtration surface is flat without irregularities. In addition, when the filter is ignited, if there is no unevenness, the fire spread speed is high, and the structure cannot stop or delay the spread of the fire, which is not preferable for ventilation fans such as kitchens.

  U.S. Patent Application Publication No. US 2004/0128260 A1 discloses a patterned airlaid nonwoven fibrous web comprising a plurality of solid projections extending from a major surface of the nonwoven fibrous web and a plurality of substantially flat land regions formed between adjacent projections. Is shown. That is, the air-laid nonwoven fiber web 70 shown in the cross-sectional shape of FIG. 16 has a three-dimensional shape including a convex portion 62 as a projection and a concave portion 61 as a land region. However, when flowing the fluid in the direction of arrow 68 in a direction substantially perpendicular to the sheet surface of the air-laid nonwoven fiber web 70, the fluid is introduced into the web 70 from the concave surface 63 at the entrance of the concave portion 61 where the thickness of the nonwoven fiber is small and the resistance is small. 68a, the filtration amount is extremely small on the vertical surface 64a provided substantially parallel to the flow. In the present structure in which almost no filtering is performed from the vertical surface 64a, efficient filtering using the entire surface cannot be performed uniformly, and filtering using the entire volume of the web 70 cannot be performed, and the advantage of the three-dimensional shape is not utilized. That is, the vertical surface 64a and the inside thereof hardly function as a filtration channel. In addition, the filtration concentrates on the concave surface (bottom surface) 63, causing local blockage by the collected matter 69. Further, as shown in FIG. There is a risk of spill 69a from web 70. Further, in the web 70 of FIG. 16, the flow 68 cannot be uniformly dispersed or distributed on the large-area and planar convex upper surface 64, and the collected matter concentrates on the convex upper surface 64 in the present structure having no top. There is also a risk of lamination.

  In addition, even when the nonwoven fabric of Patent Document 4 having no flat portion and having a flat top surface without a description of a filter application is used as a filter material, the fluid cannot be dispersed evenly throughout the filter material. It is considered that the collected matter accumulates and concentrates on the upper surface of the projection, and the amount of fluid introduced into the inside is significantly reduced after the accumulation. Usually, when traps accumulate and block on the filter surface, the filter is replaced. However, there is no conventional technique for removing the traps from the surface and reusing the filter without replacement. Further, in the case of a filter having irregularities, the filtering volume of the convex portion is larger than that of the thin concave portion and the resistance is large. Therefore, a filter that makes the filtering volume as uniform as possible is desired. Further, when the fluid to be treated contains substances of various shapes, dimensions, masses, and properties, it cannot be treated with a single-layer nonwoven fabric filter.

JP 2003-235894 A JP 2003-38567 A JP-A-2002-30561 Japanese Patent No. 5024833 JP 2011-88349 A JP 2017-225589 A JP 2014-121693 A JP 2013-538297 A

  An object of the present invention is to provide an air-laid nonwoven fabric having an uneven three-dimensional shape for improving filtration performance and a method for producing the same. It is another object of the present invention to provide an air-laid nonwoven fabric capable of improving the shape of the convex portion and the surface state of the convex surface and maintaining excellent filtration performance, and a method for producing the same. It is an object of the present invention to provide an air-laid nonwoven fabric for gas or liquid capable of suppressing clogging due to collected matter and performing uniform treatment on the entire filtration surface and the entire filter medium volume to maintain the filtration amount for a long period of time, and a method for producing the same. I do. An object of the present invention is to provide an air-laid nonwoven fabric that stops or delays the spread of fire due to ignition and a method for producing the same. An object of the present invention is to provide an air-laid nonwoven fabric capable of effectively removing oil mist and a method for producing the same. An object of the present invention is to provide an air-laid nonwoven fabric capable of treating a fluid to be treated containing various substances, and a method for producing the same.

  The present invention is an air-laid nonwoven fabric having irregularities, in which the contact area of each convex portion with the human body is small, has high liquid permeability, and enables more efficient treatment of the discharged liquid from the human body. Has a three-dimensional pattern used for sanitary products, sanitary napkins, disposable diapers and other absorbent articles, which has improved skin replenishment and improved skin comfort by reducing the area of contact with the skin. An object is to provide an air-laid nonwoven fabric and a method for producing the same. In addition, personal wipers, objective wipers, drip-absorbing sheets, various air-permeable packing materials, cushioning materials, adsorbent sheets, volatiles such as air fresheners, air filters, draining bags, tea packs, coffee filters, lye removing sheets It is an object of the present invention to provide an air-laid nonwoven fabric having a three-dimensional pattern used for, for example, and a method for producing the same.

  The air-laid nonwoven fabric of the present invention comprises a sheet body (7) containing short fibers formed from heat-adhesive fibers, and a plurality of sheets alternately provided adjacent to each other on one main surface (7a) of the sheet body (7). A concave surface (3) and a raised surface (4), a concave portion (1) having a valley surface (3) and constituting a sheet body (7), and a concave portion (1) having a raised surface (4). And a convex portion (2) constituting a sheet body (7), and a fiber density ratio between the concave portion (1) and the convex portion (2) is 1: 0.8 to 1.2. The raised surface (4) has an inclined surface (4a) formed between the center of the raised surface (4) and the valley surface (3), and the short fibers constituting the sheet body (7) are inclined surfaces (4a). And a hair fiber (5) projecting outward from the hair.

  Compared to a conventional nonwoven fabric sheet whose inclined surface is compressed and has no bristle fibers, the airlaid nonwoven fabric of the present invention has a structure in which the bristle fibers (5) extend from the inclined surface (tapered surface) (4a) of the raised surface (4). When the fluid (8) flows along the inclined surface (4a), the fluffy fiber (5) fluffing on the inclined surface (4a) becomes a resistor, and the flow of the fluid (8) is reduced. Partially hindered. As a result, a part (8a) of the fluid (8) penetrates into the seat body (7) from the inclined surface (4a) along the bristle fibers (5). At the same time, the fluid (8) is filtered by the sloping surface (4a) and the short fibers inside the sheet body (7), and solid components in the fluid (8) can be captured. The remaining part (8b) of the fluid (8) that does not enter the sheet body (7) flows further along the inclined surface (4a), and partially collides with the nap fiber (5) on the inclined surface (4a). The liquid enters the inside of the sheet body (7) from the inclined surface (4a) and is filtered, and the remainder of the fluid (8) continues to flow along the inclined surface (4a) at a reduced flow rate. By repeating the flow along the inclined surface (4a), the remainder of the fluid (8) reaches the valley surface (3) at a reduced flow rate. Thus, in the present invention, unlike the related art, there is no vertical surface where the filtration flow rate of the fluid (8) is extremely small, and the fluid (8) easily enters the inside of the sheet body (7) from the inclined surface (4b), The entire slope (4a) of the raised surface (4) can be used for filtration. For this reason, the clogging that the blockage concentrates only on the valley surface (3) due to partial filtration at the bottom of the valley surface (3) or the valley surface (3) is prevented, and the filtration flow rate is maintained. Stable filtration performance can be exhibited for a long time. The hairs, threads, debris, dust, cotton, fibers, etc. in the fluid (8) are easily collected and captured by the fluffy fibers (5) on the fluffy surface without the inclined surface (4a) being compressed. The fiber density ratio between the concave portion (1) and the convex portion (2) is approximately equal to 1: 0.8 to 1.2. Since the concave portion (1) is not compressed, the porosity between the concave portion (1) and the convex portion (2) is substantially equal, and the flow concentrates on the concave portion (1) having a small filtration volume and the valley surface (3) at the inlet thereof. The fluid (8) can flow evenly throughout the sheet body (7) without clogging. Also, when using an air-laid non-woven fabric that is folded in a pleated form, the valley surface (3) and the raised surface of one main surface (7a) are inserted without inserting an additional separating material between the opposing surfaces of the opposing non-woven fabric. (4) has the effect of preventing adhesion between nonwoven fabrics.

  In the embodiment of the airlaid nonwoven fabric of the present invention, the inclined surface (4a) constitutes a filtration surface by a plurality of hair fibers (5) and voids (15) between the hair fibers (5), The hair fibers (5) have a first hair fiber (5a) inclined to the valley surface (3) side with respect to a perpendicular (V) of the inclined surface (4a), and there are more hair fibers than the first hair fiber (5a). And a second raised fiber (5b) inclined toward the center of the raised surface (4) with respect to a perpendicular (V) of the inclined surface (4a). The second bristle fibers (5b) constitute a resistor of the fluid (8) flowing on the inclined surface (4a), and guide the fluid (8) from the gap (15) into the inside of the sheet body (7).

  During the production of the air-laid nonwoven fabric, a suction force is applied from the other main surface (7b) to the one main surface (7a) of the sheet body (7). The proportion of the heat-adhesive fibers fluffing in the direction of the main surface (7a) is large. For this reason, the number of the second hair fibers (5a) projecting toward the center of the raised surface (4) is the same as the number of the first hair fibers (5a) projecting from the inclined surface (4a) toward the valley surface (3). )is more than. Alternatively, both can be designed to have the same number or a smaller number of the second bristle fibers (5b). Therefore, the fluid (8) flowing from the center of the raised surface (4) to the inclined surface (4a) collides with the second hair fiber (5b) and the flow of the second hair fiber (5b) is reduced. Partially obstructed and guided along the second hair fibers (5b) from the gap (15) into the interior of the sheet body (7). In this case, since a large number of second bristle fibers (5b) functioning as resistors are present on the inclined surface (4a), filtration on the inclined surface (4a) is promoted. On the other hand, the first nap fiber (5a) is tilted and raised in the downstream direction of the flow, so that the fluid (8) that has collided with the first nap fiber (5a) is Flows along the inclined surface (4a) without largely entering the gap (15).

  In the embodiment of the airlaid nonwoven fabric of the present invention, the vertical cross-sectional shape of the inclined surface (4a) is straight or convex.

The vertical section of the inclined surface (4b) is formed in a straight line or a convex arc (arc shape) between the center of the raised surface (4) and the valley surface (3). Filtration of the flowing fluid (8) proceeds uniformly and gradually on the inclined surface (4b), and it is difficult for the collected matter to concentrate and accumulate on a part of the inclined surface (4b).
On the other hand, if the inclined surface is formed in a concave arc shape, filtration concentrates near the concave bottom surface and the collected matter accumulates and concentrates, and the filtration speed decreases significantly near a vertical surface substantially parallel to the fluid flow direction. I do. For this reason, if the inclined surface has a concave arc shape, the filtering performance cannot be fully exhibited.

  The embodiment of the airlaid nonwoven fabric of the present invention is provided with a top (4b), which is the highest in the vertical direction from one main surface (7a) of the sheet body (7), substantially at the center of each raised surface (4). (4b) is an apex or a curved top, the apex (4b) has a vertex on which the inclined surface (4a) is concentrated, and the curved top (4b) is an inclined surface (4a). ) Has a smaller surface area.

  The top (4b) provided substantially at the center of the raised surface (4) substantially uniformly separates the flow of the fluid (8), and forms a filtering surface with a non-perpendicular inclined surface (4a). On the other hand, in the conventional technique shown in FIG. 16, the vertical surface 64a is not a filtering surface but a dead area. In addition, the uniform separation of the fluid (8) enables volume filtration of the entire sheet body (7) inside the inclined surface (4a). Furthermore, since the top surface of the curved surface shape and the planar shape has a smaller surface area than the inclined surface (4a), a large amount of trapped matter is not accumulated only on the top portion (4b). On the other hand, in the conventional technique (FIG. 16) in which the area of the planar upper surface (top) 64 is larger than the valley surface, a large amount of trapped matter is accumulated on the convex upper surface 64.

  The embodiment of the air-laid nonwoven fabric of the present invention has a straight path (9) in which one of the main surfaces (7a) of the sheet body (7) is connected to a number of valley surfaces (3), and the straight path (9) is The fiber density of the concave portion (1) having an open end (9a) at least at one end and constituting the straight path (9) is 0.02 to 0.2.

  Since a straight path (9) connecting a large number of valley surfaces (3) is formed, the nonwoven fabric has good hand-cutting properties. That is, the thin straight path (9) functioning as a cut portion, and a plurality of convex portions (1) guiding the cut and along the straight path (9), an integrated synergistic effect, the present invention, scissors Tearing the air-laid nonwoven fabric (10) back and forth, for example by hand, from the open end (9a) along the straight path (9) according to the application and size, without using a perforation and separately forming perforations Thereby, it can be cut smoothly to a desired size.

  It is preferable when used as a household fan filter. In addition, when the collected matter is deposited on the valley surface (3), the collected water accumulated on the valley surface (3) along the straight path (9) by a water current or using a scraper. Objects can be scraped and washed, and can be easily removed from the open end (9a) of the straight path (9). Therefore, the air-laid nonwoven fabric can be used for a long period of time, and can be reused.

  If the fiber density of the concave portion (1) is less than 0.02, the tear strength and the tensile strength are weak, and the fiber may be broken before use. Also, the filtration volume is too small, and the collected matter may come off. If the fiber density exceeds 0.2, it is difficult to cut manually. In the conventional thermal bond (air-through) nonwoven fabric described later (Comparative Example 1c), since the fibers are long and vertically oriented, it is not easy to cut by hand except in the vertical direction regardless of the fiber density.

  In the embodiment of the airlaid nonwoven fabric of the present invention, the sheet body (7) contains 30 to 100% by weight of short fibers formed from a thermoadhesive fiber having a single yarn fineness of 0.2 to 60 dtex and a fiber length of 2 to 15 mm. It is a single layer.

  In the embodiment of the airlaid nonwoven fabric of the present invention, the sheet body (7) includes a part or the whole of the raised surface (4) and forms one main surface (7a) of the sheet body (7). A second layer (12) laminated on the bonding surface (11a) of the first layer (11) and the first layer (11) opposite to the one main surface (7a) of the sheet body (7). At least. Either the first layer (11) or the second layer (12) is composed of 30 to 100 short fibers formed from a thermoadhesive fiber having a single yarn fineness of 1.5 to 60 dtex and a fiber length of 2 to 15 mm. % By weight. One of the other of the first layer (11) and the second layer (12) is composed of 30 to 100 staple fibers formed from a thermoadhesive fiber having a single yarn fineness of 0.2 to 60 dtex and a fiber length of 2 to 15 mm. % By weight.

  The method for producing the air-laid nonwoven fabric of the present invention comprises a step of dispersing the defibrated thermo-adhesive fibers in an air stream and releasing them from a jetting device; Depositing a single layer or two or more layers of fiber collecting nets (27) having a concave portion (22) and a net convex portion (21) while applying a suction force, and heating and melting the deposited thermoadhesive fibers. Forming a sheet body (7) containing short fibers that are heat-sealed to each other. The sheet body (7) includes a concave portion (1) and a convex portion (2) having shapes corresponding to the net convex portion (21) and the net concave portion (22), respectively. The fiber density ratio is 1: 0.8 to 1.2, and the raised surface (4) of the convex portion (2) has a slope formed between the center of the raised surface (4) and the valley surface (3). It has a surface (4a) and a bristle fiber (5) in which short fibers constituting the sheet body (7) project outward from the inclined surface (4a).

  Since the surface is formed by the airlaid method without applying pressure, the fiber density of the concave portion (1) and the convex portion (2) is substantially constant, the surface is hardly clogged, and uniform filtration is performed over the entire volume of the nonwoven fabric. it can.

  In the embodiment of the method for producing an air-laid nonwoven fabric of the present invention, the step of depositing the thermo-adhesive fibers while applying a suction force applies a strong suction force to the net concave portion (22) as compared to the net convex portion (21). Process, a first hair fiber (5a) inclined toward the valley surface (3) with respect to a perpendicular (V) of the inclined surface (4a), and a raised surface (4) with respect to a perpendicular (V) of the inclined surface (4a). ) Forming a second fluff fiber (5b) inclined to the center side. The step of applying a strong suction force to the net concave portion (22) includes a step of forming a larger number of second hair fibers (5b) on the inclined surface (4a) than the first hair fibers (5a).

  Since a strong suction force is applied to the net recess (22), the inclined surface (4a) and the top (4b) of the air-laid nonwoven fabric corresponding to the net recess (22) are more protruding than the valley surface (3) of the recess (1). Many hair fibers (5) are fluffy.

  The suction force that flows from the main surface (27a) side of the fiber collection net (27) to the other surface (27b) side is applied, so that during the deposition, the raised surface (4) is perpendicular to the perpendicular (V) of the inclined surface (4a). ) There are a large number of second hair fibers (5b) inclined and projected toward the center side as compared with the first hair fibers (5a) inclined toward the valley surface (3). The second bristle fiber (5b) acting on the fluid with high resistance promotes filtration on the inclined surface (4a) and three-dimensional filtration inside the convex portion (2).

  The air-laid nonwoven fabric of the present invention has irregularities on the surface, and the fibers protrude from the inclined surface of the convex portion. Therefore, filtration of the inclined surface is promoted, and uniform filtration is realized on the entire surface of the irregular shape. Further, in the present invention, since the surface is not compressed, trapped matter does not concentrate on the surface, and three-dimensional filtration can be performed using the entire volume of the nonwoven fabric. Therefore, high-performance filtration can be realized without requiring long-term replacement.

  Since there are many convex surfaces on one side, the contact area with the skin is small, so that irritation to the skin is small, and the liquid discharged from the human body has a small wet feeling and a small stuffiness. In addition, since a large number of minute spaces exist between the skin and the nonwoven fabric, the feeling of high humidity and stuffiness caused by the discharged liquid are improved, and the comfort is high. On the other hand, the surface on the opposite side to the surface having the convex portion is flat, so that the transfer of the liquid to the absorbing layer is smooth.

  Furthermore, when applied to various types of personal wipers and objective wipers, the ability to remove dust and dirt is enhanced by unevenness, and when applied to drip absorbing sheets, wet back is reduced and the effect of maintaining freshness is enhanced. Further, when applied to an adsorptive sheet, the gas adsorbing effect is enhanced because the surface area is large. Further, when the present invention is applied to a lye collecting sheet, the lye trapping effect is enhanced due to the large surface area. In addition, it is also effective for volatile substances such as fragrances, various packing materials having high air permeability, cushioning materials, air filters, drain bags, tea packs, and coffee filters.

The top view which shows the airlaid nonwoven fabric by embodiment of this invention. Sectional drawing which shows the airlaid nonwoven fabric by embodiment of this invention. FIG. 2 is an enlarged cross-sectional view showing an inclined surface of the airlaid nonwoven fabric of the present invention. Enlarged sectional view showing the inclined surface of the air-laid nonwoven fabric Sectional drawing which shows the shape of the inclined surface of the airlaid nonwoven fabric of this invention. An enlarged photograph showing the shape of the inclined surface of the airlaid nonwoven fabric of the present invention. The enlarged sectional view which shows the shape of the vertex of the airlaid nonwoven fabric of this invention. FIG. 2 is a plan view showing an airlaid nonwoven fabric according to various embodiments of the present invention. Sectional drawing which shows the airlaid nonwoven fabric (multilayer structure) by other embodiment of this invention. Sectional drawing which shows the airlaid nonwoven fabric by the modification of this invention. FIG. 2 is a schematic cross-sectional view showing a state in which a fluid flows through the airlaid nonwoven fabric of the present invention. Sectional drawing which shows the fiber collection net which manufactures the airlaid nonwoven fabric of this invention. Sectional view showing a state where air-laid nonwoven fabric is deposited on the fiber collection net Schematic sectional view showing a conventional nonwoven fabric filter Schematic sectional view showing a state in which a fluid flows through a conventional nonwoven fabric filter Schematic sectional view showing a state in which a fluid flows through a conventional air-laid nonwoven fabric

  An embodiment of an airlaid nonwoven fabric and a method for producing the same according to the present invention will be described below with reference to FIGS.

  The air-laid nonwoven fabric (10) according to the present invention shown in FIGS. 1 and 2 includes a sheet body (7) containing short fibers formed from heat-adhesive fibers, and one main surface (7a) of the sheet body (7). A plurality of valley surfaces (concave surfaces) (3) and raised surfaces (convex surfaces) (4) alternately provided adjacent to each other, and a concave portion (1) having a valley surface (3) and constituting a sheet body (7). And a projection (2) having a raised surface (4) and integrally forming the seat body (7) with the depression (1).

  The heat-adhesive fibers are heat-fused and bonded to each other, and the nonwoven fabric itself is fixed in a network structure by inter-fiber bonding by melting, for example, polyolefins, polyolefins and polyesters grafted with unsaturated carboxylic acids. And polyvinyl alcohol. A core-sheath type or eccentric side-by-side type conjugate fiber is suitable as the polyolefin-based heat-adhesive fiber. Polyolefins constituting the sheath or the outer periphery of the fiber include polyethylene and polypropylene. As the polymer constituting the core component or the fiber inner layer portion, a polymer having a higher melting point than the sheath and not changing at the heating and bonding treatment temperature is preferable. The combination of the conjugate fibers is, for example, polyethylene / polypropylene, polyethylene / polyester, polypropylene / polyester, or the like, but may be modified as long as the effects of the present invention are not impaired. Further, fibril-like fibers may be used. For example, SWP of Mitsui Chemicals, Inc.

  The fiber density ratio between the concave portion (1) and the convex portion (2) constituting the sheet body (7) of the airlaid nonwoven fabric (10) is 1: 0.8 to 1.2. In the present invention, since the nonwoven fabric is formed by the airlaid method, the concave portion (1) is not compressed, and the values of the two are substantially equal. Preferably, the fiber density ratio is 1: 0.82 to 1.17. The boundary between the concave portion (1) and the convex portion (2) is shown by a broken line in FIG. The boundary can be measured by the diameter, the major axis, or the diagonal dimension of the net concave portion (22) of the fiber collecting net (27) for producing an air-laid nonwoven fabric described later.

  As shown in FIG. 2, the raised surface (4) of the convex portion (2) has an inclined surface (4a) formed between the center of the raised surface (4) and the valley surface (3), and a sheet body (7). And the fluffy fibers (5) protruding outward from the inclined surface (4a) and fluffing. Since the surface area of the raised surface (4) is larger than that of the valley surface (3), a large amount of filtration proceeds on the inclined surface (4a) which is the surface of the raised surface (4). In the conceptual cross-sectional view of the air-laid nonwoven fabric (10) of FIG. 2, the hair fibers (5) are described in a straight line for simplicity, but actually include curved hair fibers (5). The same applies to other drawings.

  As shown in FIGS. 3 and 4, the inclined surface (4 a) of the raised surface (4) constitutes a filtration surface by a plurality of hair fibers (5) and a gap (15) between the hair fibers (5). I do. The nap fiber (5) has a first nap fiber (5a) inclined to the valley surface (3) side with respect to a perpendicular (V) of the inclined surface (4a), and a larger number than the first nap fiber (5a). It has a raised hair (4) and a second hair fiber (5b) inclined to the center side with respect to the perpendicular (V) of the inclined surface (4a). The second bristle fiber (5b) constitutes a resistor of the fluid (8) flowing on the inclined surface (4a) and guides the fluid (8) from the gap (15) into the inside of the sheet body (7) (8a ). On the inclined surface (4a) of the airlaid nonwoven fabric (10) of the present invention having a large amount of the second bristle fibers (5b) shown in FIG. 3, a large amount of the fluid (8) is introduced into the sheet body (7) (8a). Therefore, three-dimensional filtration including the entire sheet body (7) can be realized. On the other hand, in the inclined surface (4a ′) containing a large amount of the first bristle fiber (5a) shown in FIG. 4 which is different from the present invention, the amount of the fluid (8) introduced into the inside of the sheet body (7) is small (8a ), Since the amount of continuous flow along the inclined surface (4a) is large (8b), the filtration is concentrated on the valley surface (3).

  The vertical cross-sectional shape of the inclined surface (4a) can be formed into a straight line as shown in FIG. 5 (a) or a convex arc as shown in FIG. 5 (b). In FIG. 5, the description of the bristle fiber (5) is omitted to clearly show the shape. FIGS. 6A and 6B are enlarged photographs corresponding to the left side of the inclined surface (4a) in FIGS. 5A and 5B, respectively. 6 (a) and 6 (b), linear and convex arc-shaped inclined surfaces (4a) and hair fibers (5) protruding from the inclined surface (4a) can be confirmed. FIG. 7 shows an embodiment of a top portion (4b) provided substantially at the center of each raised surface (4) of each convex portion (2), and FIGS. 6 (a), (b) and (c) show, respectively, Shows the tops of the pointed, curved and planar shapes. The top part (4b) is provided at the highest position in the vertical direction from one main surface (7a) of the seat body (7).

  The three-dimensional shape of each convex portion (2) is formed into a polygonal pyramid, a cone, a sphere, an oval sphere, or a trapezoid by the inclined surface (4a) and the top (4b) of the raised surface (4). The planar shape of each convex portion (2) includes a circular shape (FIG. 8A), an elliptical shape (FIG. 8B), and a hexagonal shape (FIG. 8C), in addition to the diamond shape illustrated in FIG. It is formed into a polygon. In the case of a circle, the dimension of the diameter is used, in the case of an ellipse, the dimension of the minor axis or the major axis, and in the case of a polygon, the dimension of the diagonal is 1 to 20 mm, preferably 2 to 15 mm. The height from the other main surface (7b) to the top (4b) of the seat body (7) is 0.5 to 12 mm, preferably 1 to 10 mm. When the diameter (or short diameter or diameter) of the convex portion is less than 1 mm, the effect obtained by the convex portion is small, and when it exceeds 20 mm, the sheet strength is reduced and is not practical. If the height of the projections is less than 0.5 mm, the effect obtained by the projections is small, and if it exceeds 12 mm, for example, the thickness of the collecting net (27) described later becomes too thick, and the nonwoven fabric sheet is crushed or damaged. Etc. are likely to occur, causing a problem in production. The height up to the top (4b) can be easily changed, for example, by changing the size of the convex portion (21) and the concave portion (22) of the trapping net (27) having air permeability described below, and changing the heat treatment conditions of the fibrous web. Can be adjusted.

  In the nonwoven fabric of the present invention, the zone where a large number of convex portions (2) exist may not be present on the entire surface of the sheet body (7). For example, a zone in which a number of convex portions (2) are present, and a non-existent zone may coexist in an alternating stripe shape such as vertical, horizontal, diagonal, or a zone in which a number of convex portions (2) are present. May be a pattern such as a circle or a square. Further, within the scope of the spirit of the present invention, the convex portion (2) may not have a fixed shape, and may represent a character, a wave pattern, a stripe pattern, a lattice pattern, or any pattern or logo.

  The point (4b) having a pointed shape shown in FIG. 7A has a vertex where the inclined surface (4a) is concentrated. Both the curved top (4b) and the planar top (4b) have a smaller surface area than the inclined surface (4a). Since the surface area of the curved surface and the planar top (4b) is smaller than that of the inclined surface (4a), in the present invention, the area of the planar top is larger than the valley surface, and a large amount of trapped matter is accumulated on the planar top. Unlike the prior art, the mass does not accumulate only on the top (4b).

  The ratio of the surface area of the valley surface (3) to the raised surface (4) is 1: 1.5-10. Preferably it is 1: 2-8. When the ratio is less than 1: 1.5, it is difficult to obtain the performance characteristics obtained by the convex portion (2). When the ratio exceeds 1:10, the convex portion (2) is high and the nonwoven fabric sheet is liable to be crushed or broken. Not a target. In order to set the surface area ratio in the above range, for example, the structure design of the trapping net (27) described below may be optimized. For example, in the case of the convex portion (2), the surface area is a substantial three-dimensional surface area of the raised surface (4) of the convex portion (2), not a two-dimensional projected area. The same applies to the surface area of the concave portion (1).

  The nonwoven fabric sheet of the present invention has a projected area ratio of the valley surface (2) of the concave portion (1) to the raised surface (4) of the convex portion (2) of 1: 0.2 to 4.0, preferably 1: 0. 0.4 to 3.0. When the projection area ratio is smaller than 1: 0.2, the projections (2) are small and the effect of the present invention is hardly exhibited. When the ratio of the projection areas is larger than 1: 4.0, the convex portion (2) is large and the sheet strength of the concave portion (1) is reduced, which is not practical. In order to set the projection area ratio in this range, for example, the structure design of the trapping net (27) described later may be optimized. The projection area is a ratio between the concave portion and the convex portion as a plane when the nonwoven fabric is viewed from above. That is, in FIG. 1, the projected area of the valley surface (3) of the concave portion (1) is the area around the diamond, and the projected area of the raised surface (4) of the convex portion (2) is the area of the diamond.

  As shown in FIGS. 1 and 8, the airlaid nonwoven fabric (10) can be provided with a straight path (9) in which a plurality of valley surfaces (3) are connected to one main surface (7a) of the sheet body (7). The straight path (9) has an open end (9a) at at least one end. The fiber density of the concave portion (1) constituting the straight path (9) is 0.02 to 0.2, preferably 0.03 to 0.18. The sheet body (7) is a single layer containing 30 to 100% by weight of short fibers formed of a heat-adhesive fiber having a single yarn fineness of 0.2 to 60 dtex and a fiber length of 2 to 15 mm.

  The thickness of the fiber can be selected according to the application, but the preferred fineness is from 0.2 dtex to 60 dtex, and more preferably from 0.8 dtex to 35 dtex, but the appropriate range varies depending on the application. Here, if the single-fiber fineness exceeds 60 dtex, the resulting air-laid nonwoven sheet is hard and uncomfortable, irritates the skin, and is difficult to process by hand. On the other hand, if it is less than 0.2 dtex, the productivity of the nonwoven fabric is lacking and is not practical.

  Since the number of constituent fibers is large when the heat-adhesive fiber is thin, the number of dropped fibers is small, and when applied to an absorbent article, the feel and feel are soft. When the thickness is large, the space between the fibers is large, the bulky nonwoven fabric is formed, and the air permeability is also increased. Therefore, the increase in humidity near the skin is suppressed, and the feeling of stuffiness is reduced. In addition, when the short fiber used is applied to an interpersonal wiper or an objective wiper, the fineness can be set according to the object, and the interwoven wiper has a fineness of 0.2 to 5 dtex. The fineness of the objective wiper differs depending on the application, for example, 0.2 to 5 dtex for furniture and 10 to 60 dtex for sink. The personal wiper includes a disposable towel, a wet sheet for cosmetics, a cosmetic puff, and the like, and the objective wiper includes a flooring wiper and a hand wiper.

  The length of the heat bonding fiber is preferably 2 to 15 mm. If the fibers are short, the spreadability is improved and a more uniform nonwoven fabric tends to be obtained, but if it is less than 2 mm, it becomes powdery, making it difficult to create a network structure due to inter-fiber bonding, and the strength as a nonwoven fabric is reduced, making it practical. It is not preferable because of lack of properties. On the other hand, if the length is longer than 15 mm, the strength of the nonwoven fabric is increased, but the fibers are liable to be entangled in the pneumatic transportation of the nonwoven fabric at the time of production, which is not preferable because the fiber mass defect is increased. In particular, in the airlaid method, the fiber length is short, and the lamination on the air permeable sheet having the irregularities is sufficient to form the irregularities. Therefore, the thickness is preferably 3 to 8 mm.

  In the nonwoven fabric sheet of the present invention, in addition to the above heat-adhesive fibers, recycled fibers such as rayon, semi-synthetic fibers such as acetate, synthetic fibers such as polyester, polypropylene, polyamide, and vinylon, fibril-like fibers such as SWP, Other fibers such as natural fibers such as pulp, cotton, and hemp may be included. In this case, the proportion of the heat-adhesive fibers in the nonwoven fabric sheet is preferably from 30 to 100% by weight, more preferably from 70 to 100% by weight. When the amount is less than 30% by weight, the other fibers are likely to fall off, and the wet strength may be low, which causes a practical problem. Further, when strength is required and it is not necessary to include, for example, other hydrophilic fibers, the ratio of the heat-adhesive fibers in the nonwoven fabric sheet is preferably 100% by weight.

  As shown in FIG. 9A, the sheet body (7) includes a first layer (11) that includes a part or the whole of the raised surface (4) and forms one main surface (7a) of the sheet body (7). ) And a second layer (12) laminated on the joining surface (11a) of the first layer (11) on the side opposite to the one main surface (7a) of the sheet body (7). A structured airlaid nonwoven (20) may be formed. The first layer (11) contains 30 to 100% by weight of short fibers formed from a heat-adhesive fiber having a single yarn fineness of 1.5 to 60 dtex, preferably 1.7 to 35 dtex and a fiber length of 2 to 15 mm. The second layer (12) contains 30 to 100% by weight of a short fiber formed from a thermoadhesive fiber having a single yarn fineness of 0.2 to 60 dtex, preferably 0.2 to 35 dtex and a fiber length of 2 to 15 mm. The first layer (11) and the second layer (12) may be formed in the opposite manner (that is, the eleventh embodiment is different from the tenth embodiment described later). In the airlaid nonwoven fabric (20) having a two-layer structure, the fiber density ratio between the concave portion (1) and the convex portion (2) is 1: 0.8 to 1.2, preferably 1: 0.88 to 1.19. The fiber density of the recess (1) is from 0.02 to 0.2, preferably from 0.03 to 0.11. As shown in FIG. 9B, a third layer (13) may be further laminated on the second layer (12) to form an air-laid nonwoven fabric (30) in a three-layer structure. It may be formed by laminating more than layers.

  In the above-described embodiment, the other main surface (7b) of the sheet body (7) is a plane air-laid nonwoven fabric (10), but the other main surface (7b) of the sheet body (7) has a convex portion ( A depression (6a) (FIG. 10 (a)) or a protrusion (6b) (FIG. 10 (a)) may be provided on the side opposite to the raised surface (4) of (2). When a depression (6a) is formed on the other main surface (7b) on the back side of the raised surface (4), the thickness of the projection (2) that maximizes the filtration volume is reduced, so that the projection (2) The flow of the fluid is promoted, and filtration with a uniform flow velocity is realized over the entire convex portion (2) and concave portion (1). Further, when the depression (6a) or the protruding portion (6b) is provided on the other main surface (7b) of the sheet body (7), when the airlaid nonwoven fabric is folded and pleated to be used, due to the close contact between the opposing surfaces. Stopping the filtration function can be prevented, and the filtration performance can be maintained for a long time. A depression (6a) or a protrusion (6b) may be formed on the other main surface of the sheet body (7) having a multilayer structure as well as a single layer.

An embodiment of the method for producing an air-laid nonwoven fabric according to the present invention will be described below.
In the method for producing an air-laid nonwoven fabric having a three-dimensional pattern of the present invention, a fiber collection net having a large number of convex portions and concave portions and having air permeability is used. Alternatively, a fiber collection net having a two-layer structure in which an air-permeable sheet having a large number of recesses or openings is laminated on a metal or plastic net may be used. By depositing the heat-adhesive fibers in the concave portions of the fiber collecting net, a sheet-shaped air-laid nonwoven fabric having a three-dimensional pattern of irregularities is manufactured. The method of joining the net and the air permeable sheet of the two-layer collection net can be sewn, joined with an adhesive, and heat-sealed with heat. In addition, the adhesive is limited to a material having thermal adhesiveness in at least one of the net and the air-permeable sheet.

  In the present invention, a predetermined amount of defibrated, for example, a single yarn fineness of 0.2 to 60 dtex, and a fiber length of 2 to 15 mm while uniformly dispersing the heat-adhesive fibers and other fibers as necessary in an air stream. Air is discharged from the pores of the ejection device and deposited on the fiber collecting net having a large number of recesses provided at the lower portion or on the fiber collecting net having a two-layer structure while suctioning air from the lower portion of the fiber collecting net. If necessary, after repeating this operation a plurality of times, a heat treatment is performed at a temperature higher by 15 to 40 ° C. than the melting point of the adhesive component of the heat-adhesive fiber to form a three-dimensional sheet having many irregularities. Manufactures airlaid nonwoven fabric.

  In a nonwoven fabric production method by a thermal bond method, a spunlace method, and a chemical bond method, a fiber having a long fiber length of 38 to 64 mm is generally used, so that the formation of irregularities is not sufficient. In the spun bond method and the melt blow method, since fibers are continuously spun, the formation of unevenness is also insufficient. That is, in the case of laminating a nonwoven fabric having a short fiber length and unevenness, the air laid method in which unevenness is sufficiently formed is optimal.

  The airlaid nonwoven fabric of the present invention comprises a heat-adhesive fiber and, if necessary, other fibers. That is, in addition to 100% by weight of the heat-adhesive fibers, one or more air-laid nonwoven fabrics composed of, for example, heat-adhesive fibers + pulp fibers, heat-adhesive fibers + polyester fibers, or heat-adhesive fibers + pulp fibers + chemical binders are formed. You may. Since the heat-adhesive fibers are generally low hydrophilic, the other fibers are preferably hydrophilic fibers, and include pulp fibers, rayon fibers and the like. In particular, it is preferable that the surface having the concave portion contains a heat-adhesive fiber as a main component in view of the strength of the nonwoven fabric. When the surface of the convex portion needs to exhibit water absorption, hydrophilic non-heat-adhesive fibers such as pulp fibers can be mixed, but the blending and fiber thickness can be appropriately set depending on the application. Here, “main component” means that the heat-adhesive fiber is 70% by weight or more, preferably 85% by weight or more, and may contain other fibers and pulp of 30% by weight or less.

A method for producing an air-laid nonwoven fabric according to the present invention will be described with reference to FIGS.
While uniformly dispersing a predetermined amount of the defibrated thermo-adhesive fibers as a main component in the air flow, the fibers are released from the pores of a jetting device (not shown) to form a large number of net convex portions (21) and net concave portions (22). The heat-adhesive fiber is dropped onto the fiber collecting net (27) having a single-layer or two- or more-layer structure while sucking air in the direction of the other surface (27b) (arrow 26) of the fiber collecting net (27). Is deposited on the fiber collecting net (27). If necessary, this operation is repeated a plurality of times to laminate the fibrous web, whereby the air-laid nonwoven fabric (20, 30) having the two-layer or three-layer structure can be obtained.

  When depositing the thermo-adhesive fibers on the fiber collecting net (27) while applying the suction force (26) shown in FIG. 12, as shown in FIG. 3, the concave portion (1) is positioned with respect to the perpendicular (V) of the inclined surface (4a). ), A first hair fiber (5a) inclined toward the valley surface (3) and a second hair fiber (5b) inclined toward the center of the raised surface (4) are formed. At this time, since the suction force (26) flowing in the direction of the arrow in FIG. 12 is applied from the main surface (27a) side of the fiber collecting net (27) to the other surface (27b) side, the first fuzzy fiber ( A larger number of second hair fibers (5b) are formed on the inclined surface (4a) than in 5a).

  As shown in the cross-sectional view of FIG. 12, the thickness of the fiber collecting net (27) is smaller than the net convex part (21) because the net concave part (22) is thinner, and the suction force (26c) of the net convex part (21) is smaller. A strong suction force (26a, 26b) is applied to the net recess (22) having a relatively low resistance. Therefore, as compared with the concave portion (1) of the airlaid nonwoven fabric (10) corresponding to the net convex portion (21), the inclined surface (2) of the convex portion (2) of the airlaid nonwoven fabric (10) corresponding to the net concave portion (22) ( In 4a) and the top portion (4b), there are a lot of bristle fibers (5) in which short fibers randomly protrude from the surface (FIG. 13).

  Next, heat treatment is performed at a temperature at which the deposited thermo-adhesive fiber sufficiently exhibits its adhesive effect, that is, at a temperature 15 to 40 ° C. higher than the melting point of the adhesive component of the thermo-adhesive fiber. As a result, the heat-adhesive fibers are heated and melted to form a sheet body (7) including short fibers having a network structure, which are heat-sealed and fixed to each other. That is, the sheet body (7) includes a concave portion (1) and a convex portion (2) having shapes corresponding to the net convex portion (21) and the net concave portion (22), respectively, and the concave portion (1) and the convex portion (2). And the fiber density ratio is 1: 0.8 to 1.2. An inclined surface (4a) formed between the center of the raised surface (4) and the valley surface (3), and a bristle in which short fibers constituting the sheet body (7) project outward from the inclined surface (4a). The air-laid nonwoven fabric (10) of the present invention having the fibers (5) and the raised surface (4) of the projection (2) is obtained.

  The size of the large number of net recesses (22) or openings of the fiber collection net (27) corresponds to the obtained nonwoven fabric sheet having a three-dimensional pattern. The shape has a minor axis or major axis, and the polygon has a diagonal of 1 to 20 mm, preferably 2 to 15 mm. The depth of the net concave portion (22) or opening is about 0.5 to 12 mm (corresponding to the height of the convex portion (2)). Here, “many” means a number of net recesses (22) or openings corresponding to the unevenness of the obtained air-laid nonwoven sheet, and cannot be quantitatively defined. In consideration of the strength and durability of the fiber collecting net (27), a fiber collecting net having a structure of two or more layers may be used.

  The air-permeable sheet placed on the net is preferably a knitted material whose concave portion or opening is easily designed, for example, flat knit, flat knit deformed structure, rib knit, rib knit deformed structure, double-sided knit, double-sided knitted deformed structure, pearl Knitting, weft knitting such as pearl knitting deformation structure, warp knitting such as tricot knitting, Russell knitting, and Miranese knitting can be used. In addition, a woven fabric, a net, or a nonwoven fabric may be used as long as it has a concave portion or an opening.

When a chemical binder resin is used in the method for producing the airlaid nonwoven fabric of the present invention, a hot melt adhesive, a latex adhesive, an emulsion adhesive is formed on the deposited web every time the web is formed (or the entire deposited web). , A chemical binder resin such as a resin powder adhesive or the like may be sprayed or applied. Examples of components of the chemical binder resin include polyolefins, polyvinyl acetates, polyacrylates, synthetic rubbers, polyurethanes, epoxy resins, and thermosetting resins. The amount of the chemical binder resin to be used is generally ² to 100 g / m ² , preferably 4 to 50 g / m ² in terms of solid content, and is determined within a range that does not cause bonding of the heat bonding fiber or pulp fiber or peeling of each layer. Can be

  The airlaid nonwoven fabric sheet of the present invention can be provided with functional processing such as a deodorant, an antibacterial agent, a fragrance, a humectant, a coloring agent, a hydrophilic agent, and a water repellent. The processing method is a method of mixing fibers having a function in advance, mixing a powdery agent, and spraying or impregnating a liquid agent. The nonwoven fabric manufactured by the airlaid method can randomly and three-dimensionally orient fibers in the flow direction, width direction, and thickness direction of the nonwoven fabric. Since these are thermally bonded, delamination does not occur. In addition, the nonwoven fabric manufactured by the airlaid method has good uniformity and therefore has little variation in performance.

The airlaid nonwoven fabric sheet of the present invention has a thermoadhesive fiber as a main component and a total basis weight of 16 to 800 g / m ² , preferably 20 to 300 g / m ² . If it is less than 16 g / m ² , the strength of the nonwoven fabric is reduced, and practical problems such as manufacturing processability and product handling are likely to occur. If it exceeds 800 g / m ² , the sheet will be cured, and the absorptive article will have a poor touch, causing a practical problem.

  The airlaid nonwoven sheet having a three-dimensional pattern according to the present invention has a large number of uneven portions, the ratio of the fiber density of the concave portions to the convex portions is 1: 0.8 to 1.2, and the ratio of the basis weight of the concave portions to the convex portions. Is 1: 1.2 to 20 and the ratio of the surface area of the concave portion to the surface area of the convex portion is 1: 1.5 to 10. When the airlaid nonwoven fabric sheet of the present invention is used as a topsheet of an absorbent article, the surface of the convex portion has a small contact area with the skin, so that irritation to the skin is small, and the feeling of wetness due to the discharged liquid is small and stuffy. Feeling is reduced. On the other hand, on the surface of the concave portion, the transfer of the liquid to the absorbing layer is smooth. In addition, when applied to various types of personal wipers and objective wipers, irregularities increase the ability to scrape dust and dirt, and when applied to drip absorbing sheets, reduce wet back, thereby increasing the effect of keeping fresh fish and meat fresh. In addition, it is also effective for various air-permeable packaging materials, cushioning materials, adsorptive sheets, volatile substances such as fragrances, air filters, drain bags, tea packs, coffee filters, lye removing sheets, and the like.

  Since the fiber density of the concave portion and the convex portion is substantially uniform, the density ratio is 1: 0.8 to 1.2, preferably 1: 0.9 to 1.1. To form the air-laid sheet within this range, the amount of spun air and the amount of air suction below the net may be appropriately adjusted.

  In the airlaid nonwoven fabric sheet of the present invention, since the entire fiber density is substantially uniform, the basis weight corresponding to the concave portion is consequently smaller than that of the convex portion. As a result, the weight ratio between the concave portion and the convex portion is 1: 1.2 to 20, preferably 1: 1.5 to 10. Within this numerical range, it is achieved by adjusting, for example, the thickness of the fiber collecting net corresponding to the convex portion and the total sheet weight. The basis weight of the concave portion and the convex portion is measured by punching with a small punch. When the ratio is less than 1: 1.2, it is difficult to obtain the performance characteristics obtained by the concave portions. When the ratio exceeds 1:20, the concave portions become high, and the nonwoven fabric sheet is liable to be crushed or broken, which is not practical.

An embodiment in which a gas containing oil mist is passed through the airlaid nonwoven fabric (10) of the present invention will be described below.
The gas flow (8) shown in FIG. 11 due to suction, air blowing, etc., is evenly dispersed and flows along the inclined surface (4a) when colliding with the top (4b) of the projection (2). The inclined surface (4a) has a large number of bristle fibers (5), and in particular, is inclined toward the top (4b) of the raised surface (4) with respect to the perpendicular (V) of the inclined surface (4a) (FIG. 3). Since a large amount of the second hair fiber (5b) is included, the hair fiber (5) becomes a viscous oil mist resistor and suppresses the gas flow (8). At this time, a part of the gas is introduced into the projection (2) through the gap (15) of the inclined surface (4a) while filtering off the oil mist (8a). The other part of the gas continues to flow along the inclined surface (4a) (8b), and the nap fibers (5) on the inclined surface (4a) filter out the oil mist and remove the oil mist from the gap (15) to the convex portion (2). ) (8a '). The remaining gas flows further on the inclined surface (4a) (8b '), a part of the gas flows from the inclined surface (4a) into the convex portion (2), and the remaining gas becomes a small gas flow, and the concave portion (1). ) To reach the valley surface (3) (8b ″).

  As described above, since the convex portion (2) has the top portion (4b), the air current (8) is not concentrated on one pole, but is uniformly dispersed on the entire inclined surface (4a), and as a collected matter. Oil mist does not accumulate in a part, so that the whole surface can be filtered. This effect can be obtained whether the top (4b) is a curved surface in FIG. 11 (FIG. 7B) or a pointed shape having a vertex (FIG. 7A). In addition, the inclined surface (4a) is not a smooth surface, and the hair fibers (5) protrude therefrom. In particular, since the hair fibers (5b) include a large number of the second hair fibers (5b) inclined to the top (4b) side, the resistance of the viscous oil mist is reduced. It becomes a body and easily catches oil mist. On the inclined surface (4a), the filtration is continuously repeated, and the gas is continuously introduced into the convex portion (2) from the inclined surface (4a) (8a, 8a ', 8a' '), so that the convex portion (2) and It is possible to perform three-dimensional filtration using the entire volume of the sheet body (3), that is, as shown in Fig. 11, the oil component (19) can be uniformly captured by the entire convex portion (2). When the gas reaches the valley surface (3), the amount and velocity of the gas are extremely reduced (8b ″), and the concentration of filtration on the valley surface (3) of the concave portion (1) can be suppressed.

  FIG. 11 shows an embodiment in which gas is passed through the airlaid nonwoven fabric (10) of the present invention. However, not only gas but also liquid can be treated in the same manner, and the same operation and effect can be obtained.

[Example A]
Examples of the airlaid nonwoven fabric (10, 20) according to the present invention will be described in comparison with comparative examples.

[1] Production of air-laid nonwoven fabric (10) (single layer) of the present invention (Examples 1 to 8)
<Example 1>
On a resin fiber collecting net (27) having a net concave portion (22), a heat-adhesive fiber having a fineness of 1.7 dtex having a polyethylene sheath and a polyethylene terephthalate core (PE / PET) and a fiber length of 3 mm (heat). Adhesive core-sheath type composite fiber (TJ04V4, manufactured by Teijin Limited) is deposited, and heated at 147 ° C. to heat-bond the fibers, and the concave portion (1) and the convex portion (2) are connected to one of the main fibers. An air-laid nonwoven fabric (10) having the surface (7a) was manufactured (Example 1). In Example 1, the fiber density ratio between the concave portion (1) and the convex portion (2) was 1: 0.97 and the surface area ratio was 1: 1.65, the concave portion (1) had a fiber density of 0.033, the basis weight was 80 g / m ² , FIG. 6 is a sheet having a thickness of 1.8 mm, having an elliptical convex portion (2) having a major axis of 3 mm, a minor axis of 2.5 mm, and a height of 0.9 mm, and having an inclined surface (4a) and a bristle fiber (5). An air-laid nonwoven fabric (10) equivalent to (b). The thickness was measured with a digital thickness meter FS-60DS (measuring terminal 50 mmφ, measuring load 3 g / cm ² ) manufactured by Daiei Kagaku Seiki Seisaku-Sho, Ltd. The `` basis '' is the basis weight including the concave portion (1) and the convex portion (2), the `` thickness '' is the thickness of the entire sheet, and the `` height '' is the concave portion (1) valley surface (3) to the convex portion (2) top ( 4b), and so on.

<Example 2>
Example 1 An air-laid nonwoven fabric (10) was produced by the same method and heat-bonding fiber (Example 2). In Example 2, the fiber density ratio between the concave portion (1) and the convex portion (2) was 1: 1.03 and the surface area ratio was 1: 1.57, the concave portion (1) had a fiber density of 0.062, the basis weight was 80 g / m ² , FIG. 6 (a) is a sheet having a thickness of 2.4 mm, having a rhombus convex portion (2) having a major axis of 15 mm, a minor axis of 7 mm, and a height of 2 mm, and having an inclined surface (4 a) and a bristle fiber (5). An equivalent air-laid nonwoven fabric (10).

<Example 3>
Performed except using a thermo-adhesive fiber with a fineness of 1.7 dtex and a fiber length of 5 mm (TJ04B5, manufactured by Teijin Limited) having a sheath of isophthalic acid copolymerized polyester and a core of polyethylene terephthalate (low melting point PET / PET). Example 1 An air-laid nonwoven fabric (10) was produced in the same manner as in Example 1 (Example 3). In Example 3, the fiber density ratio between the concave portion (1) and the convex portion (2) was 1: 1.05 and the surface area ratio was 1: 1.51, the concave portion (1) had a fiber density of 0.123, the basis weight was 80 g / m ² , An air-laid non-woven fabric (10 mm) which is a sheet having a thickness of 2.2 mm, has a long diameter of 15 mm, a short diameter of 7 mm, a height of 1.7 mm, has a rhombus convex portion (2), and has an inclined surface (4a) and a bristle fiber (5). ).

<Example 4>
Same as Example 1 except that a thermo-adhesive fiber having a fineness of 0.2 dt and a fiber length of 3 mm having a polyethylene sheath and a polypropylene core (PE / PP) and having a fiber length of 3 mm (product name: Aerimo QCE-K, manufactured by Ube Eximo KK) was used. The air-laid non-woven fabric (10) was manufactured by the method described in (4). In Example 4, the fiber density ratio between the concave portion (1) and the convex portion (2) was 1: 1.04 and the surface area ratio was 1: 3.94, the concave portion (1) had a fiber density of 0.183, the basis weight was 80 g / m ² , An air-laid non-woven sheet having a thickness of 1.1 mm, having an elliptical convex part (2) having a major axis of 5 mm, a minor axis of 3 mm, and a height of 0.8 mm, and having an inclined surface (4a) and a hair fiber (5). 10).

<Example 5>
An air-laid nonwoven fabric (a nonwoven fabric) was produced in the same manner as in Example 1 except that a thermoadhesive fiber (manufactured by ES Fibervisions, product name: ESC090) having a fineness of 35 dt and a fiber length of 5 mm having a polyethylene sheath and a polypropylene core (PE / PP) was used. 10) was produced (Example 5). In Example 5, the fiber density ratio of the concave portion (1) and the convex portion (2) was 1: 0.82 and the surface area ratio was 1: 9.36, the concave portion (1) had a fiber density of 0.026, the basis weight was 80 g / m ² , Airlaid nonwoven fabric (10) which is a sheet having a thickness of 3 mm, having an elliptical convex portion (2) having a major axis of 5 mm, a minor axis of 3 mm, and a height of 1.9 mm, and having an inclined surface (4a) and a hair fiber (5). It is.

<Examples 6g to 6k>
Use Example 1 the same method and the heat-adhesive fibers having a basis weight each ^{16.0g / m 2, 17.6g / m} 2, 19.2g / m 2, 20.8g / m 2 and 22.4g The air-laid non-woven fabric (10) was manufactured so as to be / m ² (Examples 6g, 6h, 6i, 6j and 6k). In Example 6g, the fiber density ratio of the concave portion (1) and the convex portion (2) was 1: 1.17 and the surface area ratio was 1: 1.65, the concave portion (1) had a fiber density of 0.032, the basis weight was 16 g / m ² , An air-laid nonwoven fabric having a thickness of 1 mm, having an elliptical convex portion (2) having a major axis of 3 mm, a minor axis of 2.5 mm, and a height of 0.9 mm, and having an inclined surface (4a) and nap fibers (5) ( 10).

<Example 7>
Example 1 An air-laid nonwoven fabric (10) was produced using the same method and using the heat-adhesive fiber so that the basis weight was 800 g / m ² (Example 7). Example 7 is a sheet having a fiber density ratio of the concave portion (1) and the convex portion (2) of 1: 1 and a surface area ratio of 1: 1.87, a concave portion (1) having a fiber density of 0.102, and a thickness of 12 mm. An air-laid nonwoven fabric (10) having an elliptical convex portion (2) having a length of 15 mm, a short diameter of 7 mm and a height of 3 mm, and having an inclined surface (4a) and nap fibers (5).

<Example 8>
A method similar to that of Example 1 was used, except that a mixed fiber of 35% by weight of the heat-adhesive fiber used in Example 1 and 65% by weight of ground pulp (manufactured by International Paper Japan Co., Ltd., product name: NF405) was used. An air-laid nonwoven fabric (10) was produced (Example 8). In Example 8, the fiber density ratio between the concave portion (1) and the convex portion (2) was 1: 0.99 and the surface area ratio was 1: 1.84, the concave portion (1) had a fiber density of 0.032, the basis weight was 80 g / m ² , An air-laid nonwoven sheet having a thickness of 1.9 mm, an elliptical convex portion (2) having a major axis of 3 mm, a minor axis of 2.5 mm, and a height of 1 mm, and having an inclined surface (4a) and nap fibers (5) ( 10).

[2] Production of nonwoven fabric (single layer) (Comparative Examples 1 to 8)
<Comparative Example 1a>
The thermo-adhesive fiber of Example 1 is deposited on a resin fiber collecting net having no net concave portion, heated at 147 ° C. and heat-fused between the fibers to form a flat (flat) air-laid nonwoven fabric. It was manufactured (Comparative Example 1a). Comparative Example 1a has a basis weight of 80 g / m ² and a thickness of 1.3 mm.

<Comparative Example 1b>
The planar air-laid nonwoven fabric of Comparative Example 1a was subjected to embossing by combining an embossing roll and an elastic roll to produce an uneven nonwoven fabric (Comparative Example 1b). Comparative Example 1b is a sheet having a fiber density ratio of concave portions to convex portions of 1: 4, concave portion (1) having a fiber density of 0.405, a basis weight of 80 g / m ² , and a thickness of 0.9 mm. It is a non-woven fabric having a rectangular projection of 0.7 mm in height.

<Comparative Example 1c>
A thermo-adhesive fiber having a fineness of 1.7 dtex having a polyethylene sheath and a polyethylene terephthalate core (PE / PET) and a fiber length of 44 mm (manufactured by Teijin Limited, The card web on which the product name (TJ04CE) was deposited was heated with hot air to produce a flat (flat) thermal bond (air through) nonwoven fabric (Comparative Example 1c). Comparative Example 1c has a basis weight of 80 g / m ² and a thickness of 1 mm.

<Comparative Example 1d>
An uneven air-laid nonwoven fabric was manufactured using the heat-adhesive fiber of Example 1 by the method described in Patent Document 4 of the prior art (Comparative Example 1d). Comparative Example 1d is a sheet having a fiber density ratio of the concave portion and the convex portion of 1: 1.05 and a surface area ratio of 1: 1.65, a concave fiber density of 0.038, a basis weight of 80 g / m ² , and a thickness of 1.7 mm, An air-laid nonwoven fabric having an elliptical convex portion having a major axis of 3 mm, a minor axis of 2.5 mm, and a height of 0.9 mm, and the convex portion has a flat upper surface and a concave inclined surface.

<Comparative Example 2>
The air-laid nonwoven fabric (10) of Example 2 was pressed at 135 ° C. and 40 g / cm ² for 1 minute using a flat type automatic press (HASHIMA, product number HP-125FA) to produce a hot-pressed nonwoven fabric (Comparative Example 2). Comparative Example 2 is a sheet having a surface area ratio of the concave portion to the convex portion of 1.32, a fiber density of the concave portion of 0.246, a basis weight of 80 g / m ² , and a thickness of 0.5 mm. The major axis is 15 mm, the minor axis is 7 mm, and the height is It is a nonwoven fabric having a 0.25 mm elliptical convex portion.

<Comparative Example 3>
A flat (flat) air-laid nonwoven fabric (10) was produced in the same manner as in Comparative Example 1a except that the heat-adhesive fiber of Example 3 was used (Comparative Example 3). Comparative Example 3 has a basis weight of 80 g / m ² and a thickness of 1.4 mm.

<Comparative Example 4>
An air-laid nonwoven fabric was produced in the same manner as in Example 1 except that a heat-adhesive fiber having a fineness of 0.1 dt and a fiber length of 3 mm having a polyethylene sheath and a polypropylene core (PE / PP) was used (Comparative Example 4). . Comparative Example 4 is a sheet having a fiber density ratio of the concave portion and the convex portion of 1: 1.07 and a surface area ratio of 1: 2.64, a concave fiber density of 0.31, a basis weight of 80 g / m ² , and a thickness of 0.7 mm. It is an air-laid nonwoven fabric having an elliptical convex portion having a major axis of 5 mm, a minor axis of 3 mm, and a height of 0.5 mm, and having an inclined surface and nap fibers.

<Comparative Example 5>
An air-laid nonwoven fabric was prepared in the same manner as in Example 1 except that a heat-adhesive fiber (manufactured by ES Fibervisions, product name: ES) having a fineness of 72 dt and a fiber length of 5 mm having a polyethylene sheath and a polypropylene core (PE / PP) was used. It was manufactured (Comparative Example 5). Comparative Example 5 is a sheet having a fiber density ratio of the concave portion to the convex portion of 1: 0.79 and a surface area ratio of 1: 8.38, a concave portion (1) having a fiber density of 0.025, a basis weight of 80 g / m ² , and a thickness of 2.8 mm. This is an air-laid nonwoven fabric having an elliptical convex portion having a major axis of 5 mm, a minor axis of 3 mm, and a height of 1.7 mm, and having an inclined surface and a hair fiber.

<Comparative Examples 6a to f>
Example 1 Using the same method and using the heat-adhesive fiber, the basis weight was 6.4 g / m ² , 8.0 g / m ² , 9.6 g / m ² , 11.2 g / m ² , and 12.8 g, respectively. / m ² and 14.4 g / m ² were prepared as air-laid nonwoven fabrics (Comparative Examples 6a, 6b, 6c, 6d, 6e and 6f). Comparative Example 6f is a sheet having a fiber density ratio of the concave portion to the convex portion of 1: 1.23 and a surface area ratio of 1: 1.65, a concave fiber density of 0.029, a basis weight of 14.4 g / m ² , and a thickness of 1 mm. It is an air-laid nonwoven fabric having an elliptical convex portion having a major axis of 3 mm, a minor axis of 2.5 mm, and a height of 0.9 mm, and having an inclined surface and nap fibers.

<Comparative Example 7>
Example 1 An air-laid nonwoven fabric was manufactured using the same method and using the heat-adhesive fiber so that the basis weight was 900 g / m ² (Comparative Example 7). Comparative Example 7 is a sheet having a fiber density ratio of a concave portion to a convex portion of 1: 1 and a surface area ratio of 1: 1.87, a concave portion fiber density of 0.108, and a thickness of 13 mm, a major axis of 15 mm, a minor axis of 7 mm, and a height of 3 mm. Is an air-laid nonwoven fabric having an elliptical convex portion and a slanted surface and nap fibers.

<Comparative Example 8>
An air-laid nonwoven fabric was produced in the same manner as in Example 1 except that a mixed fiber of 25% by weight of the heat-adhesive fiber of Example 1 and 75% by weight of the pulverized pulp of Example 8 was used (Comparative Example 8). Comparative Example 8 is a sheet having a fiber density ratio of the concave portion to the convex portion of 1: 1.01 and a surface area ratio of 1: 2.02, a concave portion fiber density of 0.031, a basis weight of 80 g / m ² , and a thickness of 2 mm. An air-laid nonwoven fabric having an elliptical convex portion having a short diameter of 2.5 mm and a height of 1.1 mm and having an inclined surface.

[3] Production of air-laid nonwoven fabric (20) (two layers) of the present invention (Examples 9 to 11)
<Example 9a>
After depositing the heat-adhesive fibers in the same manner as in Example 1, the heat-adhesive fibers of Example 4 were further laminated, and heated at 147 ° C. to heat-bond the fibers, thereby forming the concave portions (1) and the convex portions. An air-laid nonwoven fabric (20) having a two-layer structure having the part (2) on one main surface (7a) was produced (Example 9a). In Example 9a, the weight ratio of the first layer (11) to the second layer (12) was 62.5: 37.5, and the fiber density ratio of the concave portion (1) to the convex portion (2) was 1: 0. .88 and surface area ratio 1: 1.65, recess (1) sheet density 0.114, basis weight 80 g / m ² , thickness 1.2 mm, major axis 3 mm, minor axis 2.5 mm, height 0.9 mm An airlaid nonwoven fabric (20) having an elliptical convex portion (2) and an inclined surface (4a) and a nap fiber (5).

<Example 9b>
Example 9a An air-laid nonwoven fabric (10) was produced in the same manner and by using the thermoadhesive fiber (Example 9b). In Example 9b, the weight ratio of the first layer (11) to the second layer (12) was 62.5: 37.5, and the fiber density ratio of the concave portion (1) and the convex portion (2) was 1: 0. .97 and a surface area ratio of 1: 1.5, recessed part (1) A sheet with a fiber density of 0.085, a basis weight of 80 g / m ² and a thickness of 2.1 mm, a long diameter of 15 mm, a short diameter of 7 mm, and a height of 1.3 mm rhombus An air-laid nonwoven fabric (20) having a convex portion (2) and having an inclined surface (4a) and a bristle fiber (5).

<Example 10>
On a resin fiber collecting net (27) having a net recess (22), a heat-adhesive fiber having a fineness of 11 dtex having a polyethylene sheath and a polypropylene core (PE / PP) and a fiber length of 5 mm (Koyama Chemical Co., Ltd.) ), Product name S / S 006-1) was deposited, and the heat-adhesive fibers of Example 1 were further laminated, and heated at 147 ° C. to heat-bond the fibers to each other, thereby forming concave portions (1) and convex portions ( An air-laid nonwoven fabric (20) having a two-layer structure having 2) on one main surface (7a) was produced (Example 10). In Example 10, the weight ratio of the first layer (11) to the second layer (12) was 62.5: 37.5, and the fiber density ratio of the concave portion (1) to the convex portion (2) was 1: 0. .95 and a surface area ratio of 1: 3.31, a concave portion (1) having a fiber density of 0.03, a basis weight of 80 g / m ² and a thickness of 2.7 mm, a major axis of 3 mm, a minor axis of 2.5 mm, and a height of 1.8 mm An airlaid nonwoven fabric (20) having an elliptical convex portion (2) and an inclined surface (4a) and a nap fiber (5).

<Example 11>
After the heat-adhesive fibers were deposited in the same manner as in Example 1, the heat-adhesive fibers used in the first layer (11) of Example 10 were further laminated, and heated at 147 ° C. to heat the fibers. By fusion, an air-laid nonwoven fabric (20) having a two-layer structure having a concave portion (1) and a convex portion (2) on one main surface (7a) was produced (Example 11). In Example 11, the weight ratio of the first layer (11) to the second layer (12) was 62.5: 37.5, and the fiber density ratio of the concave portion (1) and the convex portion (2) was 1: 1. .19 and a surface area ratio of 1:65, a concave portion (1) having a fiber density of 0.027, a basis weight of 80 g / m ² , and a thickness of 1.8 mm, a major axis of 3 mm, a minor axis of 2.5 mm, and a height of 0.9 mm An airlaid nonwoven fabric (20) having an elliptical convex portion (2) and an inclined surface (4a) and a nap fiber (5).

[4] Production of air-laid nonwoven fabric (two layers) (Comparative Example 9)
After the heat-adhesive fibers were deposited in the same manner as in Comparative Example 1a, the heat-adhesive fibers of Example 4 were further laminated, and heated at 147 ° C. to heat-bond the fibers to form a flat (flat) shape. An air-laid nonwoven fabric having a two-layer structure was manufactured (Comparative Example 9). In Comparative Example 9, the weight ratio of the first layer to the second layer was 62.5: 37.5, the basis weight was 80 g / m ² , and the thickness was 0.9 mm.

[5] Test method Examples and comparative examples were tested by the following method.
[5-1] Air permeability test The air permeability was measured using AP-360SM manufactured by Daiei Kagaku Seiki Seisakusho in accordance with the Japanese Industrial Standard L1096A method (Fragile method). That is, after each test piece of about 200 mm × 200 mm collected from the examples and comparative examples was attached to one end of the cylinder of the Frazier type testing machine, the suction fan and the inclining fan were set so that the tilt type barometer showed a pressure of 125 Pa by the rheostat. Adjust the air hole and measure the pressure indicated by the vertical barometer at that time. From the measured pressure and the type of air hole used, the amount of air (cm ³ / cm ² · s) passing through the test piece was determined from a conversion table attached to the tester.

[5-2] Retention capacity test Using DFT-3T1N manufactured by Tokyo Dilek Co., gas was passed through the sheets of Examples and Comparative Examples, and the weight of the captured dust when the pressure loss reached 150 Pa was measured and retained. The volume (mg) was used. JIS test powder (11 types of JIS Z 8901, Kanto loam fired product) was used as the dust.

[5-3] Dust holding amount test Each sample of Examples and Comparative Examples was punched out into a circle having a diameter of 13 cm, and the surface having convex portions or the surface having no convex portions was provided with 11 types of JIS test powders. After flattening 3 g of the powder, the holding amount of the powder was measured after 1 minute with the powder attached surface facing down with a 10 mm pitch wire mesh.

[5-4] Oil Retention Amount The sheets of Examples and Comparative Examples each having a size of 5 cm × 5 cm were immersed in oil for 1 minute, cut off the oil with a horizontal wire net for 1 minute, and then the oil holding weight of the sheet was measured.

[5-5] Mist collection amount test Place 1 kg of unused salad oil in a pan, surround the IH cooking heater and the top and four sides of the pan with an aluminum frame, and place it horizontally on top of an aluminum frame 70 cm higher than the pan. Each sheet of the example and the comparative example of 25 cm × 40 cm was attached, and the upper 20 cm × 20 cm opening was heated with a 1400 W output IH cooking heater at 180 ° C. for 6 hours while exhausting the opening with a ventilation fan. Was measured and converted to the amount of mist per 1 m ² .

[5-6] Combustion test Based on the 45 ° micro-burner method (A-1 method) of the flammability test method for textile products of Japanese Industrial Standards (JIS L-1091), the degree of spread of combustion in Examples and Comparative Examples (Burning length and burning area), residual flame and residual dust time were measured, and the flammability classification was calculated from the measured values. Here, `` combustion area '' is the total area of the portion destroyed by combustion or pyrolysis under specified test conditions, `` combustion length '' is the maximum length of the portion destroyed by combustion or pyrolysis, "Afterflame time + residual dust time" represents the time from the end of heating to the time when the red heat of the test piece stops.

[5-7] Tensile strength test Regarding the examples and the comparative examples, the tensile strength was measured with a Forster (A & D Co., Ltd. product number MCT-2150) at a sample width of 50 mm, a chuck distance of 100 mm, and a tensile speed of 300 m / min. It was measured.

[6] Test results and discussion The compositions and test results of each of the examples and comparative examples are shown in Tables 1 to 4 and discussed below. All the fineness units “t” shown in the column of “fiber composition” in the table mean “dtex”.

[6-1] Air permeability From Tables 1, 2 and 4, Examples 1, ² , 5, 6 g, 10 and 11 according to the present invention show excellent air permeability of 170 cc / cm ² / sec or more, and are air filters. It is suitable for. On the other hand, Comparative Example 4 having a low fineness (0.1 dtex), Comparative Example 7 having a high basis weight (900 g / m ² ), and Comparative Example 9 having a flat two-layer structure have low air permeability of 35 cc / cm ² / sec or less. And not suitable for filters.

[6-2] Retention Capacity From Table 1, Examples 1 and 2 showed excellent retention capacity values of 588 mg or more, and Comparative Example 1b showed a low retention capacity value of 140 mg. That is, in the comparative example 1b of the heat embossing, as described in the related art (FIG. 15), the flow concentrates on the concave portion, but because of the heating and compression, clogging occurs early and is not suitable for a filter. On the other hand, the airlaid nonwoven fabric (10) of the present invention has a high retention capacity without clogging because it is filtered using the entire surface and the entire volume because the surface is not compressed.

[6-3] Dust holding amount From Tables 1, 2 and 4, Examples 8, 9a and 9b show particularly excellent values of the dust holding amount of 1.23 g / sheet or more. Nos. 7 and 11 also exhibited good dust retention values of 0.61 g / sheet or more. In the present invention, since the surface is fluffy and a lot of the bristle fibers (5) protrude from the inclined surface (4a) of the convex portion (2), dust is easily captured and held. Comparative examples 1a, 3 and 9 of flat, comparative examples 1b and 2 of hot embossing and pressing, comparative example 1d having flat convex upper surface and concave inclined surface, low fineness (0.1 dtex) and high fineness (72 dtex) Comparative Examples 4 and 5 and Comparative Example 6f having a low basis weight (14.4 g / m ² ) exhibited a low dust retention value of 0.39 g / sheet or less.

[6-4] Oil Retention From Tables 1, 2 and 4, from Example 7 having a large basis weight of 800 g / m ² and Example 10 using a fiber having a fineness of 11 dtex for the first layer (11), It showed a particularly excellent oil retention value of 2154 g / m ² or more. Examples 1, 2, 3, 5, 8, 9b and 11 also showed good oil retention values of 1016 g / m ² or more. In the above embodiment, since a considerable amount of oil can be retained, it is preferable as a filter for a ventilation fan that catches an oil absorbent or an oil mist. Comparative Examples 1b, 2, 4 and 6f show a low oil retention value of 488 g / m ² or less, and when used in a ventilation fan filter, there is no oil retention, so even if the oil is once held, the oil is quickly removed. It may fall and is not suitable for ventilation fans.

[6-5] Amount of mist collection From Tables 1, 2 and 4, Examples 1, 2, 3, 8, 9a and 9b show excellent mist collection values of 0.11 g / sheet or more. Preferred as a ventilator filter. In Comparative Example 1b of hot embossing and Comparative Example 2 of hot pressing, oil was not sufficiently introduced and absorbed from the surface of the non-woven fabric because the surface and inside were compressed during production, and the oil could not be retained. The following values of the low mist collection amount are shown.

[6-6] Combustion performance According to Tables 1 and 2, Examples 1, 2, 3 and 6 g are all excellent in the combustion length of 7.6 cm or less, the combustion area of 10.9 cm ² or less, and the combustion classification of 3. The values of the combustion performance are shown. Since the number of fibers in the concave portion (1) is small, the carbonization distance and carbonization area are expected to be small. In Comparative Example 1b of hot embossing and Comparative Example 2 of hot pressing, the combustion length was 26.5 cm or more, the combustion area was 46 m ² or more, and the combustion classification was 1 and the combustion performance was low. It is considered that the fibers were dense and the distance between the fibers was short.

[6-7] Tensile Strength In the following, the tensile strength is considered in the machine direction (MD) of the nonwoven fabric in a dry (DRY) state. From Table 3, Examples 6g to 6k showed excellent tensile strength values of 1.05 kgf / 50 mm or more, and Examples 6a to 6f showed low tensile strength values of 0.58 kgf / 50 mm or less. For this reason, the lower limit of the basis weight of the air-laid nonwoven fabric having a high tensile strength is considered to be 16.0 g / m ² (Example 6 g). From Tables 1, 2 and 4, Example 7 shows a particularly excellent tensile strength value of 50 kgf / 50 mm or more, and Examples 1 to 4, 9a and 9b show good tensile strength values of 8.9 kgf / 50 mm or more. showed that. Comparative Examples 5, 6f and 8 exhibited low tensile strength values of 0.9 kgf / 50 mm or less. Comparative Example 8 also has a large amount of short fibers and pulp falling off and is not suitable for a filter.

[7] Conclusion From the above test results and considerations, Examples 1 and 2 are in all the test items of [6-1] to [6-7], and Example 3 is in all the test items except for the air permeability. It showed excellent values and proved to be an extremely high-performance filtration material. Examples 7, 8, 9a, 9b and 11 also showed excellent values in three of the five tested items, indicating that they were high-performance filtration materials. It is believed that the above examples can be universally used as filtration materials for all applications. Example 4 has a high tensile strength and a fine fiber, and thus is suitable for a filter for business use (for air-conditioning equipment such as a clean room, for a dust mask, for dust collection or for a vacuum cleaner), and Examples 5 and 10 show air permeability and Because of high oil retention, it is suitable for ventilation fan filters in factories and the like that use a lot of oil. Example 6g has high air permeability and shows excellent combustion performance, so it is suitable for ventilation fan filters in kitchens and kitchens that use fire. Furthermore, Examples 6g to 6k were found to be suitable for commercial filters under high pressure or high water pressure conditions because of higher tensile strength than Comparative Examples 6a to 6f. As described above, the first embodiment of the present invention having the nap fiber (5) on the inclined surface (4a) of the convex portion (2), especially having a large number of the first nap fiber (5) and having the top portion (4b) ~ 11 were found to have excellent filtration properties. Preferred ranges of the physical properties of the airlaid nonwoven fabric of the present invention are shown below according to Examples.

  As for the range of the fiber density ratio between the concave portion (1) and the convex portion (2), from Tables 1 and 2, the single-layer air-laid nonwoven fabric (10) is 1: 0.82 (Example 5) to 1: 1.17. (Example 6g) is preferable, and from Table 4, the air-laid nonwoven fabric (20) having a two-layer structure is preferably from 1: 0.88 (Example 9a) to 1: 1.19 (Example 11). Therefore, it was found that the air-laid nonwoven fabrics (10, 20) both having a single layer and a double structure had substantially the same fiber density ratio. With respect to the fiber density range of the concave portion (1), from Tables 1 and 2, the single-layer airlaid nonwoven fabric (10) is preferably from 0.026 (Example 5) to 0.183 (Example 4), and from Table 4, two layers are preferable. The airlaid nonwoven fabric (20) having the structure is preferably from 0.027 (Example 11) to 0.114 (Example 9a). In all embodiments of the present invention having a low density of 0.2 or less, a straight path (9) connecting a large number of valley surfaces (3) and a large number of convex portions (2) arranged in parallel to the straight path (9) are used. The air-laid nonwoven fabric (10, 20) can be easily and neatly cut by tearing along the line.

As for the range of fineness, Table 1 and Table 2 show that the single-layer air-laid nonwoven fabric (10) is preferably from 0.2 dtex (Example 4) to 35 dtex (Example 5). Is preferably from 0.2 dtex (Examples 9a and 9b) to 11 dtex (Examples 10 and 11). With respect to the content range of the thermoplastic fiber, from Tables 1 and 2, the single-layer air-laid nonwoven fabric (10) is preferably from 35% by weight (Example 8) to 100% by weight (all Examples other than Example 8). Further, regarding the shape of the convex portion (2), from Tables 1, 2 and 4, the air-laid nonwoven fabric (10, 20) has an elliptical shape (Examples 1, 4, 5, 6g to 6k, 8, 9a, 10 and 11). And diamonds (Examples 2, 3, 7 and 9b) are preferred.
[Example B]

Hereinafter, the evaluation of the objective wiper and the evaluation of the adsorptive sheet were performed as follows.
<Evaluation of dry objective wiper>
A floor wiping test was performed based on the following floor wiper test method as a dry objective wiper. In the test method, the nonwoven fabric sheets of the following examples and comparative examples were cut into 200 mm x 300 mm to obtain flooring wipers. Spread them separately on the same kind of cleaning tools, then spray 0.2g each on the floor, 4 kinds of JIS test powder, 7 kinds of JIS test powder, cotton linter, and 10 pieces each Each of the cleaned hairs was wiped and cleaned, and the weight (number of hairs) of each substance before and after the cleaning tool was reciprocated two times was measured, and the reduction rate was measured. The test was performed three times each, and the average value was calculated. Table 5 shows various physical properties of the nonwoven fabric sheet.

<Evaluation of adsorptive sheet (ammonia deodorization rate)>
As an adsorptive sheet, an ammonia gas adsorption test was performed based on the following test method. First, airlaid nonwoven sheets were manufactured as the following examples and comparative examples. Next, 30 μl of a 9% aqueous ammonia solution was dropped into a 20 L Tedlar (R) bag, which was then sealed and left for 24 hours to evaporate the ammonia. Initial ammonia concentration, and 65 mm x 160 mm x 2 sheets each of the sheets of Examples and Comparative Examples were sealed in a 3 L Tedlar (R) bag, and the residual ammonia in the gas collected from the bag after being left at room temperature for 24 hours. The concentration was measured using a gas detector tube. The deodorization rate was determined from the following equation. The test was performed three times each, and the average value was calculated.
Deodorization rate = {1- (residual ammonia concentration) / (initial ammonia concentration)} × 100 (%)
Table 6 shows various physical properties of the nonwoven fabric sheet.

<Evaluation of lye collecting sheet (evaluation of lye trapping amount)>
In addition, a test was performed as a lye-removing sheet based on the following test method. 500 cc of water, 20 g of tallow (cow), and 180 g of lean beef are put in an aluminum pan having a diameter of 20 cm and a depth of 8.5 cm, and a circular lye sheet having a diameter of 20 cm shown in Table 7 is further cut into a semicircle. The sheet was cut, and two kinds of the example and the comparative example were placed at the same time. This state was set as the first time, and after boiled for 10 minutes, the cooking sheet was taken out, air-dried, and the adhesion amount of lye solids was measured. Then, it was calculated by the following equation (1). Next, as a second time, the lye-removing sheet was exchanged, and after boiling for 10 minutes in the same manner as in the first time, the cooking sheet was taken out and air-dried to measure the amount of lye solid adhered. Was calculated by Here, the lye trapping amount W (g / m ² ) was calculated by the following equation.
W = (W2-W1) (1)
here,
W1: Weight of the lye sheet before use (g)
W2: Weight (g) of air-dried lye sheet after use
Table 7 shows various physical properties of the nonwoven fabric sheet.

Example B1 (Evaluation of absorbent article)
A commercially available tricot knitted fabric (see FIG. 1 (for the sake of convenience, the opening is formed on a collecting net made of polyethylene terephthalate (PET)) so as to have the shape shown in FIGS. Spherical), the opening is an elliptical sphere, the major axis is 3.0 mm, the minor axis is 2.5 mm, the openings are arranged in a staggered pattern, and the number is 6.60 / cm ² ). A net that was laminated and integrated was used. On this, 70% by weight of a heat-adhesive conjugate fiber (manufactured by Teijin Limited, product name TJ04V4, 1.7 dtex × 3 mm) made of sheath PE (polyethylene) / core PET, and ground pulp (product name NB-, manufactured by Weyerhaeuser) 405) was mixed at a ratio of 30% by weight, and heated at 147 ° C. in a hot oven by an air laid method so as to be 45 g / m ² to cause inter-fiber bonding. An air-laid nonwoven sheet having a part height of 1.1 mm and a three-dimensional pattern on one side was obtained. As a result of actual measurement of the obtained sheet, the ratio of the fiber density of the concave portions to the convex portions was 1: 0.94, and the ratio of the basis weight of the concave portions to the convex portions was 1: 1.9. Also, as a result of calculating the major axis of the elliptical spherical convex part from the major axis of 3.0 mm, the minor axis of 2.5 mm, and the height of 1.1 mm, the surface area ratio of the concave part to the convex part is 1: 1.6, and the concave part and the convex part The projected area ratio of the part was 1: 0.63. Here, when the topsheet of a commercially available sanitary product was peeled off and replaced with this sheet with the protruding portions on the surface, menstrual blood could be quickly absorbed and hardly returned. In addition, the skin had a good smooth feel, good touch and was useful.

Example B2 (Evaluation of absorbent article)
Conditions except that the opening of the tricot knitted fabric is elliptical spherical, the major axis is 5.5 mm, the minor axis is 2.2 mm, the apertures are arranged in a staggered manner, and the number is 4.41 pieces / cm2. Was carried out in the same manner as in Example B1 to obtain an air-laid nonwoven sheet having a three-dimensional pattern on one side and having a height of the protrusion of 2.6 mm. As a result of actually measuring the obtained sheet, the ratio of the fiber density between the concave portions and the convex portions was 1: 1.02, and the ratio of the basis weight between the concave portions and the convex portions was 1: 4.5. Also, as a result of calculating the major axis of the elliptical sphere with a major axis of 5.5 mm, a minor axis of 2.2 mm, and a height of 2.6 mm, the surface area ratio between the concave section and the convex section is 1: 9.5, and the concave section and the convex section are calculated. The projected area ratio of the part was 1: 0.72. Here, when the topsheet of a commercially available sanitary product was peeled off and replaced with this sheet with the convex portion as the surface, menstrual blood could be quickly absorbed and hardly returned. In addition, the skin had a good smooth feel, good touch and was useful.

Comparative Example B1 (Evaluation of absorbent article)
As the air-laid collection net, a normal net without the tricot knitted fabric (only the fiber collection net 11 in FIG. 2) was used, and the other conditions were the same as in Example B1. A 0.8 mm thick sheet flat on both sides was obtained. When the topsheet was peeled off and replaced with a commercially available sanitary product in the same manner as in Example B1, menstrual blood absorption was slower than in Examples B1 and B2, and there was no protrusions and depressions, so there was a feeling of clinging to the skin. And the smooth feeling was small.

Comparative Example B2 (Evaluation of absorbent article)
Japanese Patent No. 5024833 discloses an air-laid collection net “a predetermined amount of defibrated thermo-adhesive fibers as a main component. Dropping the fibers blown out of the net onto a metal or plastic fiber collection net installed at the lower part, on which a projection made of synthetic resin is locally provided. The fibers are deposited on the net while suctioning air at the lower part, and if necessary, this operation is repeated a plurality of times. Then, the temperature is further raised by 15 to 40 ° C. higher than the melting point of the adhesive component of the heat-adhesive fiber. And the other conditions were the same as in Example B1. A sheet having a thickness of 1.0 mm was obtained in which one side of the depressed portion had an elliptical spherical shape. When the topsheet was peeled off from the commercially available sanitary product and replaced as in the case of Example B1, compared to Example B1, water was slightly retained in the depressed portion and the feeling of smoothness was small. This is probably because the comparative example B2 has a large number of concave portions and the contact area with the skin is large, as compared with the example B1 having a large number of convex portions.

Comparative Example B3 (Evaluation of absorbent article)
The same thing as Comparative Example B1 was embossed by a combination of an embossing roll and an elastic roll in a later step to obtain an uneven sheet. The embossed shape was the same as in Example B1. As in Example B1, the topsheet was peeled off from a commercially available sanitary product and replaced for use. As compared with Example B1, the concave portions were higher in density than the convex portions. The feeling was small.

Example B3 (Evaluation of dry objective wiper)
Using the same collecting net and tricot knit as in Example B1, a net was used in which both were laminated and integrated. On this, 70% by weight of a heat-adhesive conjugate fiber (manufactured by Teijin Limited, product name TJ04V4, 1.7 dtex × 3 mm) made of sheath PE (polyethylene) / core PET, and ground pulp (product name NB-, manufactured by Weyerhaeuser) 405) were mixed at a ratio of 30 wt%, in air-laid process so as to be 30 g / m ^2, by causing interfiber bonding by heating at 147 ° C. by heat oven has a recess and a convex portion on one side, a convex An air-laid nonwoven sheet having a three-dimensional pattern on one side having a thickness of 1.0 mm was obtained. Here, evaluation as a flooring wiper was performed by the method described above. The results are shown in Table 1. As compared with Comparative Example B4 and Comparative Example B5, the superiority of the reduction rate of each substance, that is, the dust removal rate was observed due to the effect of the scraping property by the convex surface.

Example B4 (Evaluation of a dry objective wiper)
Using the same collecting net and tricot knit as in Example B2, a net was used in which both were laminated and integrated. Other conditions were the same as in Example B3. An air-laid nonwoven sheet having a concave portion and a convex portion on one side and a thickness of the convex portion of 1.9 mm and having a three-dimensional pattern on one side was obtained. Here, evaluation as a flooring wiper was performed by the method described above. The results are shown in Table 5. As compared with Comparative Example B4 and Comparative Example B5, the superiority in the reduction rate of each substance, that is, the dust removal rate was observed due to the effect of the scraping property by the convex surface. The dust removal rate was superior to that of Example B3, which is considered to be because the irregular shape was larger than that of Example B3.

Example B5 (Evaluation of a dry objective wiper)
Using the same collecting net and tricot knit as in Example B2, a net was used in which both were laminated and integrated. On this, 70% by weight of a heat-adhesive conjugate fiber composed of sheath PE (polyethylene) / core PET (trade name: TJ04C2, 56dtex × 5mm, manufactured by Teijin Limited), pulverized pulp (trade name: NB-405, manufactured by Weyerhaeuser) Was mixed at a ratio of 30% by weight, and heated at 147 ° C. in a heat oven by an air laid method so as to be 30 g / m ² to cause inter-fiber bonding. An air-laid nonwoven sheet having a thickness of 1.9 mm and having a three-dimensional pattern on one side was obtained. Evaluation as a flooring wiper was performed by the method described above. The results are shown in Table 1. As compared with Comparative Example B4 and Comparative Example B5, the superiority of the reduction rate of each substance, that is, the dust removal rate was observed due to the effect of the scraping property by the convex surface. Note that, compared to Example B4, the fiber was thicker, so that the dust removal rate was superior even in cotton linters and hair, but four types of fine dust JIS test powder and JIS test powder were used. The seven powders were inferior.

Comparative Example B4 (Evaluation of a dry objective wiper)
An ordinary net (only the fiber collection net 11 in FIG. 2) on which no tricot knit was laminated was used as the airlaid collection net, and the other conditions were the same as in Example B3. A 0.7 mm thick sheet flat on both sides was obtained. Here, evaluation as a flooring wiper was performed by the method described above. The results are shown in Table 5, and the reduction rate of each substance, that is, the dust removal rate was inferior to Examples B3 to B5.

Comparative Example B5 (Evaluation of a dry objective wiper)
The same thing as Comparative Example B4 was embossed by a combination of an embossing roll and an elastic roll in a later step to obtain an uneven sheet. The emboss shape was the same as that of Example B3. Here, evaluation as a flooring wiper was performed by the method described above. The results are shown in Table 5. The reduction rate of each substance slightly exceeded that of Comparative Example B4, but the reduction rate of each substance, that is, the dust removal rate, was lower than those of Examples B3 to B5.

Example B6 (Evaluation of deodorization rate)
Using the same collecting net and tricot knit as in Example B1, a net was used in which both were laminated and integrated. On this, 50% by weight of a heat-adhesive conjugate fiber (manufactured by Teijin Fibers Ltd., product name TJ04V4, 1.7 dtex × 3 mm) composed of sheath PE (polyethylene) / core PET, pulverized pulp (product name: NB manufactured by Weyerhaeuser) -405) was mixed at a ratio of 50% by weight, and heated at 147 ° C. by an air laid method at 147 ° C. by an air laid method so as to be 60 g / m ² to cause inter-fiber bonding. An air-laid nonwoven fabric sheet having a three-dimensional pattern on one side and a convex portion having a thickness of 1.2 mm was obtained. Here, the ammonia gas adsorption performance was evaluated by the method described above. The results are shown in Table 6. As compared with Comparative Examples B6 and B7, superiority in ammonia gas adsorption performance was observed. This is attributed to the increase in surface area due to the uneven surface.

Comparative Example B6 (Evaluation of deodorizing rate)
As an air-laid net, a normal net (only the fiber net 11 shown in FIG. 2) having no tricot knit was used, and the other conditions were the same as in Example B6. A 0.9 mm thick sheet flat on both sides was obtained. Here, the ammonia gas adsorption performance was evaluated by the method described above. The results are shown in Table 6, and the ammonia gas adsorption performance was inferior to Example B6.

Comparative Example B7 (Evaluation of deodorant rate)
The same thing as Comparative Example B6 was embossed by a combination of an embossing roll and an elastic roll in a later step to obtain an uneven sheet. The embossed shape was the same as in Example B6. Here, the ammonia gas adsorption performance was evaluated by the method described above. The results are shown in Table 2, and the adsorption performance of ammonia gas was inferior to that of Example B6. Although the ammonia gas adsorption performance was inferior to Comparative Example B6, it is considered that this was due to the fact that the density of the concave portions was increased by embossing.

Example B7 (Evaluation of amount of trapped lye)
Using the same collecting net and tricot knit as in Example B1, a net was used in which both were laminated and integrated. A thermo-adhesive conjugate fiber (manufactured by Teijin Fibers Co., Ltd., product name: TJ04V4, 1.7 dtex × 3 mm) made of sheath PE (polyethylene) / core PET was air-laid on this to be 40 g / m ² at 100% by weight. By heating at 147 ° C. in a heat oven to generate fiber-to-fiber bonding, an air-laid nonwoven sheet having a concave portion and a convex portion on one surface and a convex portion having a thickness of 1.0 mm and having a three-dimensional pattern on one surface. Obtained. Here, the evaluation as a lye extract sheet was performed by the method described above. The results are shown in Table 7, and the superiority was seen in the amount of lye trapping compared to Comparative Example B8.

Example B8 (Evaluation of amount of lye trapped)
Using the same collecting net and tricot knit as in Example B2, a net was used in which both were laminated and integrated. Other conditions were the same as in Example B7. An air-laid nonwoven sheet having a concave portion and a convex portion on one surface and a thickness of the convex portion of 2.0 mm and having a three-dimensional pattern on one surface was obtained. Here, the evaluation as a lye extract sheet was performed by the method described above. The results are shown in Table 7, and the superiority was seen in the amount of lye trapping compared to Comparative Example B8. In addition, although superiority was seen in the amount of lye trapping compared with Example B7, it is considered that the unevenness is larger than that in Example B7.

Comparative Example B8 (Evaluation of the amount of lye trapped)
As an air-laid net, a normal net (only the fiber net 11 shown in FIG. 2) without a tricot knit was used, and the other conditions were the same as in Example B7. A 0.8 mm thick sheet flat on both sides was obtained. Here, the evaluation as a lye extract sheet was performed by the method described above. The results are shown in Table 7, but were inferior in the amount of lye trapping compared to Examples B7 and B8.

  The airlaid nonwoven fabric of the present invention can be used not only for gas or liquid filters but also for sanitary products, disposable diapers, other absorbent articles, personal wipers, objective wipers, drip absorbent sheets (fresh food rugs), and high air permeability. It can also be used for packaging materials, buffer materials, adsorptive sheets for gas adsorption, volatilizers used for fragrances, filters, draining bags, tea packs, coffee filters, and lye removing sheets.

  (1) ・ ・ Recess, (2) ・ ・ Protrusion, (3) ・ ・ Valve surface, (4) ・ ・ Protruded surface, (4a) ・ ・ Slope surface, (5) ・ ・ Fuzzy fiber, (5a ) First fuzzy fiber (5a), (5b) ... Second fuzzy fiber, (7) ... sheet body, (7a) ... one main surface, (8) ... fluid, (9) ··· Straight road, (9a) ··· Open end, (11) ··· First layer, (12) ··· Second layer, (15) ··· Void, (21) ·· Net convex Part, (22) ・ ・ Net recess, (27) ・ ・ Fiber collecting net,

  The air-laid nonwoven fabric of the present invention comprises a sheet body (7) containing short fibers formed from heat-adhesive fibers, and a plurality of sheets alternately provided adjacent to each other on one main surface (7a) of the sheet body (7). A concave surface (3) and a raised surface (4), a concave portion (1) having a valley surface (3) and constituting a sheet body (7), and a concave portion (1) having a raised surface (4). And a convex portion (2) constituting a sheet body (7), and a fiber density ratio between the concave portion (1) and the convex portion (2) is 1: 0.8 to 1.2. The raised surface (4) has an inclined surface (4a) formed between the center of the raised surface (4) and the valley surface (3), and the short fibers constituting the sheet body (7) are inclined surfaces (4a). And a hair fiber (5) projecting outward from the outer surface, the longitudinal cross-sectional shape of the inclined surface (4a) is linear or convex, and the approximate center of each raised surface (4) is ) Has a highest top (4b) in the vertical direction from one main surface (7a), and the top (4b) of each raised surface (4) is a top with a pointed or curved shape, and a top with a pointed shape ( 4b) has an apex where the inclined surface (4a) is concentrated, and the curved top portion (4b) has a smaller surface area than the inclined surface (4a).

  In the airlaid nonwoven fabric of the present invention, the vertical cross-sectional shape of the inclined surface (4a) is a straight line or a convex arc.

  The airlaid nonwoven fabric of the present invention includes a top (4b), which is vertically highest from one main surface (7a) of the sheet body (7), substantially at the center of each raised surface (4), and the top (4b) is , A pointed or curved top, the pointed top (4b) has an apex where the inclined surface (4a) is concentrated, and the curved top (4b) has a smaller surface area than the inclined surface (4a). Having.

The method for producing the air-laid nonwoven fabric of the present invention comprises a step of dispersing the defibrated thermo-adhesive fibers in an air stream and releasing them from a jetting device; Depositing a single layer or two or more layers of fiber collecting nets (27) having a concave portion (22) and a net convex portion (21) while applying a suction force, and heating and melting the deposited thermoadhesive fibers. Forming a sheet body (7) containing short fibers that are heat-sealed to each other. The sheet body (7) includes a concave portion (1) and a convex portion (2) having shapes corresponding to the net convex portion (21) and the net concave portion (22), respectively. The fiber density ratio is 1: 0.8 to 1.2, and the raised surface (4) of the convex portion (2) has a slope formed between the center of the raised surface (4) and the valley surface (3). Surface (4a), the short fibers constituting the sheet body (7) have a bristle fiber (5) projecting outward from the inclined surface (4a), and the vertical cross-sectional shape of the inclined surface (4a) is a straight line. Shape or convex arc shape, substantially the center of each raised surface (4) is provided with the highest top (4b) in the vertical direction from one main surface (7a) of the sheet body (7), and each raised surface (4) The top (4b) is a point having a pointed or curved surface, the pointed top (4b) has an apex where the inclined surface (4a) is concentrated, and the top (4b) having the curved surface has an inclined surface. (4a) It has a smaller surface area.

Claims (9)

A sheet body containing staple fibers formed from heat-adhesive fibers,
A number of valley surfaces and raised surfaces alternately provided adjacent to each other on one main surface of the sheet body,
A concave portion having a valley surface and constituting a sheet body,
A convex portion having a raised surface and integrally forming the sheet body with the concave portion,
In an airlaid nonwoven fabric in which the fiber density ratio between the concave portion and the convex portion is 1: 0.8 to 1.2,
An air-laid nonwoven fabric, wherein the raised surface has an inclined surface formed between the center of the raised surface and the valley surface, and bristle fibers in which short fibers constituting the sheet body project outward from the inclined surface. . The inclined surface constitutes a filtration surface by a plurality of hair fibers and voids between the hair fibers,
The fuzzy fibers have a first fuzzy fiber inclined to the valley surface side with respect to a perpendicular to the inclined surface, and a second fuzzy fiber which is present in a larger number than the first fuzzy fiber and inclines toward the center of the raised surface with respect to the perpendicular to the inclined surface. With nap fibers,
2. The airlaid nonwoven fabric according to claim 1, wherein the second bristle fiber constitutes a resistor of a fluid flowing on the inclined surface, and guides the fluid from the gap into the inside of the sheet body. 3.   The air-laid nonwoven fabric according to claim 1 or 2, wherein a vertical cross-sectional shape of the inclined surface is a straight shape or a convex arc shape. At the approximate center of each raised surface, there is a vertically highest peak from one main surface of the seat body,
The top is a pointed or curved top,
The top of the pointed shape has a vertex where the inclined surface is concentrated,
The airlaid nonwoven fabric according to claim 3, wherein the top of the curved surface has a smaller surface area than the inclined surface. A straight path that connects many valley surfaces to one main surface of the seat body,
The straight path has an open end at least at one end,
The air-laid nonwoven fabric according to any one of claims 1 to 4, wherein a fiber density of the concave portion forming the straight path is 0.02 to 0.2.   6. The sheet body according to claim 1, wherein the sheet body is a single layer containing 30 to 100% by weight of short fibers formed of a heat-adhesive fiber having a single yarn fineness of 0.2 to 60 dtex and a fiber length of 2 to 15 mm. 4. The airlaid nonwoven fabric according to item 1. The sheet body includes a first layer that includes a part or the whole of the raised surface and forms one main surface of the sheet body, and a bonding surface of the first layer opposite to the one main surface of the sheet body. At least a laminated second layer,
Either the first layer or the second layer contains 30 to 100% by weight of a short fiber formed from a thermoadhesive fiber having a single yarn fineness of 1.5 to 60 dtex and a fiber length of 2 to 15 mm,
The other one of the first layer and the second layer contains 30 to 100% by weight of a short fiber formed from a thermoadhesive fiber having a single yarn fineness of 0.2 to 60 dtex and a fiber length of 2 to 15 mm. The air-laid nonwoven fabric according to any one of Items 1 to 5, above. Dispersing the defibrated thermo-adhesive fibers in an air stream and discharging them from a jetting device;
The step of depositing the released heat-adhesive fibers on a single-layer or two- or more-layer fiber collection net having air permeability and a large number of net recesses and net projections while applying suction force,
Heat-fusing the deposited heat-adhesive fibers, forming a sheet body containing short fibers that are heat-sealed to each other,
The sheet body includes a concave portion and a convex portion having shapes corresponding to the net convex portion and the net concave portion, respectively, and the fiber density ratio between the concave portion and the convex portion is 1: 0.8 to 1.2,
The raised surface of the convex portion is characterized by having an inclined surface formed between the center of the raised surface and the valley surface, and a bristle fiber in which short fibers constituting the sheet body project outward from the inclined surface. Of air-laid non-woven fabric. The step of depositing the thermo-adhesive fibers while applying suction force,
A step in which a strong suction force is applied to the net concave portion compared to the net convex portion,
Forming a first fuzzy fiber inclined to the valley surface side with respect to a perpendicular to the inclined surface, and a second fuzzy fiber inclined to the raised surface center side with respect to the perpendicular to the inclined surface,
The method for producing an air-laid nonwoven fabric according to claim 8, wherein the step of applying a strong suction force to the net concave portion includes a step of forming a larger number of second hair fibers than the first hair fibers on the inclined surface.