KR20180033123A - Fiber laminate - Google Patents

Abstract

A first fiber layer having a first major surface and comprising a first fiber aggregate and a second fiber layer composed of a second fiber aggregate as a fiber layer disposed on the first main surface, At least one of the main surfaces on the first fibrous layer side has the first surface irregularities and the height of the convex portions constituting the first surface irregularities is 0.1 mm or more.

Description

Fiber laminate {FIBER LAMINATE}

The present invention relates to a fiber laminate which can be preferably used as a filter material or the like.

It is known to use a fiber layer such as a nonwoven fabric or a laminate including a plurality of fiber layers as a filter medium represented by an air filter medium (air filter), a mask and the like.

For example, in Japanese Patent No. 5205650 (Patent Document 1), a fiber layer A which is a polyolefin-based nonwoven fabric having an average fiber diameter of 0.6 to 1.8 탆 and a thickness of 0.03 to 0.1 mm and an average fiber diameter of 5 to 60 탆 and a thickness of 0.15 to 1.5 And a fibrous layer B which is a polyolefin fiber layer having a specific surface area A / mm, and a density, a thickness ratio of the fibrous layer A and the fibrous layer B, and an air permeability of the air layer. According to the description of Patent Document 1, this laminate has a high air permeability and a collection efficiency.

Japanese Patent No. 5205650 Specification

An object of the present invention is to improve the ventilation performance and the collection performance of a fibrous body which can be used for a filter medium or the like.

The present invention provides the following fiber laminate.

[1] A nonwoven fabric comprising: a first fiber layer having a first major surface and composed of a first fiber aggregate;

And a second fibrous layer composed of a second fibrous aggregate, the fibrous layer being disposed on the first main surface,

At least one of the first main surface and the main surface on the first fibrous layer side of the second fibrous layer has a first surface irregularity,

And the height of the convex portion constituting the first surface irregularities is 0.1 mm or more.

[2] The fiber laminate according to [1], wherein the density of the convex portions constituting the first surface unevenness is 3 / cm 2 or more.

[3] The fiber laminate according to any one of [1] or [2], wherein at least the first main surface has the first surface irregularities.

[4] The optical fiber according to any one of [1] to [3], wherein the main surface of the second fiber layer opposite to the first fiber layer has a second surface irregularity and the height of the convex portion constituting the second surface irregularity is 0.05 mm or more. Wherein the fiber bundle is a fiber bundle.

[5] The fiber laminate according to [4], wherein the density of the convex portions constituting the second surface unevenness is 3 / cm 2 or more.

[6] The fiber laminate according to any one of [1] to [5], wherein the bulk density is 0.1 g / cm 3 or less.

[7] The fiber laminate according to any one of [1] to [6], wherein the ratio T ₁ / T ₂ of the thickness T ₁ of the first fiber layer to the thickness T ₂ of the second fiber layer is 4 to 25.

[8] The fiber laminate according to any one of [1] to [7], wherein the first fibrous aggregate and the second fibrous aggregate are nonwoven fibrous aggregates.

[9] The fiber laminate according to [8], wherein the nonwoven fibrous aggregate comprises a polyolefin-based resin fiber.

[10] The fiber laminate according to any one of [1] to [9], wherein the fibers constituting the second fiber aggregate have an average fiber diameter of 0.5 to 2 μm.

[11] The fiber laminate according to any one of [1] to [10], wherein the air permeability is not less than 100 cc / cm 2 / s.

[12] A gas-liquid separator according to any one of [1] to [8], wherein the collecting efficiency and the pressure loss measured according to JIS T 8151 are 85%

QF value = -ln (1-collecting efficiency (%) / 100) / pressure loss (Pa)

, The QF value calculated according to the following formula (1) is 0.6 or more.

[13] The fiber laminate according to any one of [1] to [12], which has undergone the charging treatment.

[14] The fiber laminate according to any one of [1] to [13], which is a filter material.

[15] The fiber laminate according to any one of [1] to [13], which is a cleaning article.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a fiber body excellent in ventilation performance and trapping performance. The fibrous body (fiber laminate) according to the present invention is suitable for a filter material such as an air filter material and a mask.

1 is a schematic cross-sectional view showing an example of a fiber laminate according to a first embodiment of the present invention.
2 is a schematic cross-sectional view showing an example of a fiber laminate according to a second embodiment of the present invention.
3 is a schematic cross-sectional view showing an example of a fiber laminate according to a third embodiment of the present invention.
4 is a schematic sectional view showing an example of a fiber laminate according to a fourth embodiment of the present invention.
5 is a schematic sectional view showing an example of a fiber laminate according to a fifth embodiment of the present invention.
6 is a table micrograph of one end face of the fiber laminate related to Example 1. Fig.

The present invention provides a fiber aggregate comprising a first fiber layer having a first major surface and composed of a first fiber aggregate and a second fiber layer composed of a second fiber aggregate as a fiber layer disposed on the first main surface, At least one of the first main surface (inner main surface) and the first main surface (inner main surface) on the first fibrous layer side of the second fibrous layer has surface irregularities. Hereinafter, embodiments of the present invention will be described in detail.

(First Embodiment)

1 is a schematic cross-sectional view showing an example of a fiber laminate according to a first embodiment of the present invention. The fiber laminate shown in Fig. 1 includes a first fiber layer 1 composed of a first fiber aggregate and a second fiber layer 2 arranged on the first main surface 11 and composed of a second fiber aggregate do. The first fibrous layer 1 has a first main surface 11 on the side of the second fibrous layer 2 and a second main surface 11 on the opposite side of the second fibrous layer 2 (Main outer circumferential surface) 12. The second fibrous layer 2 has a first main surface 21 on the side of the first fibrous layer 1 and a second main surface opposite to the first main surface 21 on the side opposite to the first fibrous layer 1, (Outer circumferential surface) 22.

The first main surface 11 of the first fibrous layer 1 is made of surface irregularities and the second fibrous layer 2 is laminated thereon. The second fibrous layer (2) is in contact with the first main surface (11) of the first fibrous layer (1) over the entire surface or substantially the entire surface. Therefore, the first main surface 21 of the second fibrous layer 2 also has a surface irregularity, which is a transfer type (or a substantially transfer type) surface irregularities of the first main surface 11 of the first fibrous layer 1. That is, the interface between the first fibrous layer 1 and the second fibrous layer 2 is composed of irregularities. In the present specification, the surface irregularities that the first main surface 11 of the first fibrous layer 1 and / or the first main surface 21 of the second fibrous layer 2 can have are collectively referred to as " first surface irregularities " .

In the fiber laminate shown in Fig. 1, the second main surface 22 of the second fiber layer 2 also has surface irregularities. In the present specification, the surface irregularities that the second main surface (outer main surface) 22 of the second fibrous layer 2 can have are referred to as " second surface irregularities ". In the fiber laminate shown in Fig. 1, the first main surface 12 of the first fiber layer 1 also has surface irregularities. In the present specification, the surface irregularities that the second main surface (outer main surface) 12 of the first fibrous layer 1 can have are referred to as " third surface irregularities ".

As exemplified by the fibrous laminate shown in Fig. 1, the fibrous laminate according to the present embodiment (the same also applies to the other embodiments described later) is formed by the first main surface 11 and the second main surface 11 of the first fibrous layer 1, At least one of the first main surface 21 of the fibrous layer 2 has a first surface irregularity. According to the fiber laminate related to this embodiment, it is possible to combine high air permeability and high collection performance. The fiber laminate related to this embodiment can be preferably used for a filter material such as an air filter material and a mask. Since the fibrous laminate according to the present embodiment has a painful performance (low pressure loss) when it is applied to, for example, a human-made mask, it can not feel the breathing well, It is possible to effectively collect foreign substances in gases such as viruses, dust, dust, house dust, pollen, and dust, because it has a high collecting performance. In addition, when applied to, for example, an industrial air filter material, since it has a painful performance, it can increase the processing speed of filtration (foreign matter removal) and has a high trapping performance. Therefore, And can be collected at a high collection efficiency and / or at a high collection capacity.

The fibrous laminate according to the present embodiment (the same also applies to the other embodiments described later) is formed by using the second surface irregularities of the second main surface 22 of the second fibrous layer 2, It is also possible to use it as a cleaning tool typified by a wiper for removing, for example, foreign matter as described above.

In the present invention, the main surface having the first surface irregularities need only have the first surface irregularities in at least a part thereof, and it is not necessary that all of them are made of the first surface irregularities. The same applies to the second and third surface irregularities. However, from the viewpoint of further improving the ventilation performance and the collecting performance, it is preferable that all of the main surfaces having the first surface irregularities (or substantially all of them) are formed of the first surface irregularities. The same applies to the second and third surface irregularities.

Hereinafter, the fiber laminate related to this embodiment (first embodiment) will be described in more detail.

(1) The first fiber layer

The first main surface 11 (the main surface on the side of the second fibrous layer 2) has a first surface irregularity, and the first main surface (inner main surface) 11 The outer major surface 12 has a third surface irregularity. The first main surface 11 is preferably made of the first surface irregularities and the second main surface 12 is preferably made of the third surface irregularities. The first surface irregularities of the first main surface 11 are the surfaces forming the interface with the second fibrous layer 2 (and thus the first main surface 21 of the second fibrous layer also has the first surface irregularities) Since the interface of the fibrous layer is composed of the irregularities, it is possible to enhance the trapping performance and the ventilation performance of the fiber laminate. Also, having the third surface irregularities is advantageous in further improving the collection performance and the ventilation performance. The convex portions of the first major surface (inner major surface) 11 and the second major surface (outer major surface) 12 may be present regularly or randomly. The shape of the convex portion is not particularly limited and may be, for example, a conical shape, a cylindrical shape, a pyramid shape, a bristle shape, or the like.

From the viewpoint of enhancing the collecting performance of the fiber laminate, the height of the convex portion constituting the first surface irregularities of the first main surface (inner main surface) 11 is 0.1 mm or more, preferably 0.2 mm or more, 0.3 mm or more (for example, 0.4 mm or more). The height of the convex portion is usually 5 mm or less, preferably 3 mm or less (for example, 2 mm or less). If the height of the convex portion is too low and the height is less than 0.1 mm and the first main surface 11 is relatively smooth, the improvement of the collecting performance is not confirmed or becomes insufficient. If the convex portion is excessively high, the mechanical strength of the fiber laminate is deteriorated. From the viewpoint of enhancing the collecting performance of the fiber laminate, the density of the convex portions in the first surface irregularities is preferably 3 / cm2 or more, more preferably 10 / cm2 or more. The density of the convex portion is usually 50 / cm2 or less, and typically 30 / cm2 or less. If the density of the convex portion is excessively large, the air permeability of the fiber laminate may be adversely affected. The heights and densities of the convex portions were measured according to the method described in the section of Example using a table microscope. The height and density of the convex portions constituting the third surface irregularities may be the same as the height and density of the convex portions constituting the first surface irregularities of the first fibrous layer 1, respectively.

The first fibrous aggregate constituting the first fibrous layer 1 may be composed of a woven fabric, but is preferably a non-woven fibrous aggregate. Among them, the first fiber aggregate is more preferably a melt blown nonwoven fibrous aggregate. By using the melt blowing method, a nonwoven fabric aggregate having a small bulk density and excellent air permeability and having a first surface irregularity and further a third surface irregularity can be easily and inexpensively manufactured. As the melt blowing method, a general melt blowing spinning device can be used.

In the case of using the melt blowing method, the first fiber layer 1 is produced as a fiber web obtained by collecting the fiber stream injected from the nozzles on the uneven surface of the collector. That is, the fibers intrude into the concave portion (or the penetrating portion) of the collecting surface and solidify, so that unevenness is imparted to one main surface or both main surfaces of the first fibrous aggregate. The collector may be a metal collector formed with a plurality of (or a plurality of) convex portions or concave portions, a wire mesh having a mesh, a needle cloth, or the like. Among them, it is preferable to use a net having a three-dimensional structure generally called a conveyor net, whereby it is possible to more easily manufacture the nonwoven fabric aggregate having the first surface irregularities and further the third surface irregularities.

The convex portion constituting the first surface irregularities may be provided with protrusions of brushed shape. The brim shaped protrusions preferably have rigidity. When a net such as a conveyor net is used as the collecting body, the convex portion tends to be a bristle-shaped projection. As will be described later, the fiber laminate is produced by spraying a fiber for forming the second fiber aggregate on the first main surface 11 of the first fiber aggregate (first fiber layer 1) prepared in advance by the melt blowing method or the like However, if the convex portion constituting the first surface irregularities is a protruding portion of a bristle shape, the bonding strength between the first fibrous layer 1 and the second fibrous layer 2 is increased, whereby the durability of the fiber laminate can be enhanced.

The average fiber diameter (first average fiber diameter) of the fibers constituting the first fiber aggregate is preferably 5 to 50 mu m, more preferably 7 to 25 mu m. If the first average fiber diameter is within the above range, the first fibrous aggregate (first fibrous layer 1) is imparted with rigidity such that the first surface concavo-convexity, that is, the shape of the third surface concavo-convex, can do. It is also advantageous to improve the balance between the air permeability and the trapping performance of the fiber laminate by setting the first average fiber diameter in the above range. If the first average fiber diameter is too small, the ventilation performance tends to decrease. If the first average fiber diameter is too large, the collection performance tends to deteriorate.

The fibers constituting the first fiber aggregate usually include fibers made of a thermoplastic resin. Specific examples of the thermoplastic resin include polyolefin resins (low density, medium density or high density polyethylene, poly C _2-4 olefin resins such as polypropylene, etc.); Styrene resins (heat-resistant polystyrenes and the like); Polyester resins (poly-C _2-4 alkylene arylate resins such as polyethylene terephthalate resin, polytrimethylene terephthalate resin, polybutylene terephthalate resin and polyethylene naphthalate resin); A polyamide resin (an aliphatic polyamide resin such as polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610 and polyamide 612, a semiaromatic polyamide resin, polyphenylene isophthalamide , Aromatic polyamide resins such as polyhexamethylene terephthalamide and poly p-phenylene terephthalamide); Polycarbonate resins (such as bisphenol A polycarbonate); Polyurethane resins; Based resin (such as cellulose ester). Among them, a polyolefin resin, a polyester resin, and a polyamide resin are preferably used, and a polyolefin resin is more preferably used. The fibers constituting the first fiber aggregate may contain two or more kinds of thermoplastic resins.

Among polyolefin resins, polypropylene is preferably used. A polyolefin resin, particularly polypropylene, can be easily charged by a charging treatment to be described later, so that a fiber laminate capable of further increasing the filtration performance (collection performance) by charging can be obtained more easily. In the case where the fibers constituting the first fiber aggregate contain polypropylene, the fibers may be composed solely of polypropylene or may contain a thermoplastic resin other than polypropylene. In the latter case, the content of the polypropylene is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more.

The fiber constituting the first fibrous aggregate may be selected from the group consisting of inert additives such as stabilizers (heat stabilizers, ultraviolet absorbers, light stabilizers, antioxidants), antimicrobial agents, deodorants, perfumes, coloring agents An antistatic agent, a flame retardant, a plasticizer, a lubricant, and the like. The additive may be used alone or in combination of two or more. The additive may be carried on the surface of the fiber or contained in the fiber.

The melt flow rate (MFR, 230 ° C, 21.18 N load) of the polypropylene is preferably 400 g / 10 min or less, and more preferably 200 g / 10 min or less. If the MFR exceeds 400 g / 10 min, the fiber flow discharged from the nozzle is easily refined and it may be difficult to maintain a high average fiber diameter. From the viewpoint of resin dischargeability from the nozzle, the MFR of the polypropylene is preferably 10 g / min or more.

The inherent viscosity of the polyester-based resin is preferably 0.7 or more, and more preferably 0.8 to 1.5. The relative viscosity of the polyamide-based resin is preferably 2 or more, and preferably 2.2 to 3.0. By using such a resin, it is easy to produce a melt-blown nonwoven fabric aggregate having a high average fiber diameter.

In the case where the first fiber aggregate is a melt-blown nonwoven fibrous aggregate, in order to form a first fiber aggregate exhibiting a rigidity sufficient to maintain the shape of the first surface irregularities, that is, the third surface irregularities even after being formed into a fiber laminate , It is preferable that the fibers of the melt blown fiber flow are thick before the fibers are fined and that the fibers reach the collecting surface before the fibers are solidified. Since it is necessary to cleanly peel off the trapping surface having concavo-convex after the fiber flow is solidified, it may be necessary to cool the trapping surface.

Further, in order to form the first fibrous aggregate exhibiting the aforementioned rigidity, it is preferable to lengthen the time until solidification by shortening the collection distance of the fiber flow or increasing the resin viscosity to make the fiber diameter large Do. The collection distance is, for example, 5 to 100 cm, preferably 10 to 60 cm. The resin viscosity varies depending on the resin to be used and the melting temperature, but is, for example, 10 to 100 Pa · s, and preferably 20 to 50 Pa · s.

First and one fibrous layer (1) the apparent weight W ₁ is, in view of the aeration performance and absorption performance (collection efficiency and / or the collecting capacity of foreign matter), preferably 5 ~ 100 g / ㎡ of (the first fiber aggregates), More preferably 10 to 50 g / m < 2 > or more. If the apparent weight W ₁ is too small, it is difficult to obtain sufficient filtration performance. If the apparent weight W ₁ is excessively large, good ventilation performance is hardly obtained. The density (bulk density) D ₁ of the first fiber layer 1 in the fiber laminate is preferably 0.005 to 0.5 g / cm 3, more preferably 0.01 to 0.2 g / cm 3 from the viewpoint of the air permeability . If the density D ₁ is excessively large, the ventilation performance may be deteriorated. If the density D ₁ is too small, it is difficult to obtain sufficient filtration performance, and the mechanical strength of the fiber laminate may be lowered.

The thickness T ₁ of the first fiber layer 1 in the fiber laminate is preferably 0.3 to 5 mm from the viewpoint of the ventilation performance and the collection performance (the collection efficiency of foreign matter and / or the collection capacity) Is 0.4 to 3 mm. By setting the thickness T ₁ within the above range, the first fibrous layer 1 exhibiting the above-described rigidity can be easily obtained, and good ventilation performance and collection performance (including trapping capacity) can be obtained.

From the viewpoint of balance between the ventilation performance and the collection performance, the air permeability of the first fibrous layer 1 (first fibrous aggregate) is preferably 100 to 1000 cc / cm2 / s as the air permeability by the Frazier method, 110 to 800 cc / cm 2 / s, and more preferably 120 to 500 cc / cm 2 / s (for example, 130 to 400 cc / cm 2 / s). If the air permeability of the first fiber layer 1 is too low, the air permeability of the fiber laminate tends to become insufficient. If the air permeability of the first fiber layer 1 is too high, it is difficult to obtain a sufficient collection performance.

(2) The second fibrous layer

The second fiber layer 2 is a layer composed of a second fiber aggregate. The first main surface 21 (main surface on the side of the first fiber layer 1) may have a first surface irregularity, The second main surface (outer major surface) 22 may have a second surface irregularity. The first main surface 21 is preferably made of the first surface irregularities and the second main surface 22 is preferably made of the second surface irregularities. It is preferable that at least the first main surface 11 of the first fibrous layer 1 has a first surface irregularity as in the present embodiment and that the first fibrous layer 1 and the second fibrous layer 2 have a surface roughness, Both of the first main surface 11 of the second fibrous layer 2 and the first main surface 21 of the second fibrous layer 2 have a first surface irregularity. Further, if the second main surface 22 of the second fibrous layer 2 has the second surface irregularities, it is advantageous to improve the collecting performance and the ventilation performance. The convex portions of the first main surface (inner major surface) 21 and the second major surface (outer major surface) 22 of the second fibrous layer 2 may be present regularly or randomly. The shape of the second convex portion is not particularly limited and may be, for example, a conical shape, a cylindrical shape, a pyramid shape, a bristle shape, or the like.

The height and the density of the convex portion of the first main surface 21 of the second fibrous layer 2 are the same as those of the convex portion of the first main surface 11 The above techniques are cited.

The height of the convex portion constituting the second surface irregularities of the second main surface 22 is preferably 0.05 mm or more, more preferably 0.1 mm or more, and still more preferably, 0.2 mm or more (for example, 0.3 mm or more). The height of the convex portion is usually 5 mm or less, preferably 3 mm or less (for example, 2 mm or less). If the convex portion is excessively low and the height is less than 0.05 mm and the second main surface 22 is smooth, the improvement of the collecting performance is not confirmed or becomes insufficient. If the convex portion is excessively high, the mechanical strength of the fiber laminate is deteriorated. From the viewpoint of enhancing the collecting performance of the fiber laminate, the density of the convex portion in the second surface irregularities is preferably 3 / cm2 or more, more preferably 10 / cm2 or more. The density of the convex portion is usually 50 / cm2 or less, and typically 30 / cm2 or less. If the density of the convex portion is excessively large, the air permeability of the fiber laminate may be adversely affected.

The second fibrous aggregate constituting the second fibrous layer 2 may be composed of woven fabric, but is preferably a nonwoven fibrous aggregate. Among them, the second fiber aggregate is more preferably a melt blown nonwoven fibrous aggregate. According to the melt blowing method, the second fiber aggregate (second fiber layer 2) made of fibers having a desired average fiber diameter is subjected to a separate heat-sealing step such as thermal embossing or an adhesive step using an adhesive or the like , It is easy to laminate or further adhere to the previously prepared first fibrous layer 1.

The average fiber diameter (second average fiber diameter) of the fibers constituting the second fiber aggregate is preferably smaller than the average fiber diameter (first average fiber diameter) of the fibers constituting the first fiber aggregate. Specifically, the second average fiber diameter is preferably 0.5 to 2 占 퐉, and more preferably 0.7 to 1.5 占 퐉. When the second average fiber diameter is within this range, the collection performance of the fiber laminate can be enhanced, and the balance between the air permeability and the collection performance of the fiber laminate can be improved. An excessively small second average fiber diameter may be detrimental to the breathability performance. An excessively large second average fiber diameter may be detrimental to the collection performance.

A specific example of the fiber material constituting the second fiber aggregate may be the same as the first fiber aggregate. Among them, a polyolefin resin, a polyester resin, and a polyamide resin are preferably used, and a polyolefin resin is more preferably used. The fibers constituting the second fiber aggregate may contain two or more kinds of thermoplastic resins. Among polyolefin resins, polypropylene is preferably used. A polyolefin resin, particularly polypropylene, can be easily charged by a charging treatment to be described later, so that a fiber laminate capable of further increasing the filtration performance (collection performance) by charging can be obtained more easily.

In the case where the fibers constituting the second fiber aggregate contain polypropylene, the fibers may be composed solely of polypropylene or may contain a thermoplastic resin other than polypropylene. In the latter case, the content of the polypropylene is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more.

The fiber constituting the second fibrous aggregate may be selected from among commonly used additives such as stabilizers (heat stabilizer, ultraviolet absorber, light stabilizer and antioxidant), antimicrobial agent, deodorant, perfume, coloring agent An antistatic agent, a flame retardant, a plasticizer, a lubricant, and the like. The additive may be used alone or in combination of two or more. The additive may be carried on the surface of the fiber or contained in the fiber.

The melt flow rate (MFR, 230 ° C, 21.18 N load) of the polypropylene is preferably 500 g / 10 min or more, and more preferably 700 g / 10 min or more. When the MFR is less than 500 g / 10 min, the fiber stream discharged from the nozzle is not readily fine-grained and it may be difficult to maintain a low average fiber diameter. From the viewpoint of resin dischargeability from the nozzle, the MFR of the polypropylene is preferably not more than 2000 g / min.

In the case where the second fibrous aggregate is a melt blown nonwoven fibrous aggregate, the second average fiber diameter of the fibers constituting the second fibrous aggregate is preferably such that the collecting distance of the fiber flow is longer than that at the time of producing the first fibrous aggregate, Can be controlled by adjusting the blow condition.

The apparent weight W ₂ of the second fibrous layer 2 (second fibrous aggregate) is preferably smaller than that of the first fibrous layer 1 (the first fibrous aggregate), and the ventilation performance and the collecting performance (the collecting efficiency of the foreign matter and / Is preferably 0.5 to 30 g / m 2, and more preferably 1 to 10 g / m 2 or more, from the viewpoint of the water absorption capacity If the apparent weight W ₂ is too small, it is difficult to obtain sufficient trapping performance. If the apparent weight W ₂ is excessively large, it is difficult to obtain a good ventilation performance. The density (volume density) D ₂ of the second fibrous layer 2 in the fiber laminate is preferably 0.007 to 0.4 g / cm 3, more preferably 0.015 to 0.3 g / cm 3 from the viewpoint of the air permeability . If the density D ₂ is excessively large, the ventilation performance may be deteriorated. If the density D ₂ is too small, it is difficult to obtain sufficient collection performance.

The thickness T ₂ of the second fibrous layer 2 in the fiber laminate is preferably smaller than the thickness of the first fibrous layer 1 and is preferably in the range of from the viewpoint of the ventilation performance and the trapping performance Is preferably 0.01 to 2 mm, more preferably 0.03 to 1 mm, and still more preferably 0.03 to 0.5 mm (e.g., 0.1 mm or less). By setting the thickness T ₂ within this range, a balance between the ventilation performance and the collection performance is improved.

(3) Fiber laminate

In the fiber laminate according to the present embodiment, the thickness ratio of the first fibrous layer 1 and the second fibrous layer 2 to the first fibrous layer 1 and the second fibrous layer 2 in order to provide not only surface irregularities but also a higher balance of the ventilation performance and the collecting performance, It is preferable to suitably adjust at least one (preferably two or more, more preferably all) of the apparent weight ratio and the density (bulk density) ratio. A first fiber layer (1) thickness T ₁ and the ratio T ₁ / T ₂ having a thickness T ₂ of the second fiber layer (2) is preferably 4 to 25, more preferably 6 to 20. In addition, the apparent weight W ₁ and an apparent weight ratio W ₁ / W ₂ of W ₂ of the second fiber layer (2) of the first fiber layer 1 is preferably 3-20, more preferably from 4 to 15 . The ratio D ₁ / D ₂ of the density (bulk density) D ₁ of the first fiber layer ₁ to the density (bulk density) D ₂ of the second fiber layer ₂ is preferably 0.2 to 0.99, 0.3 to 0.8.

The thickness (total thickness) of the fiber laminate is preferably 0.4 to 7 mm, and more preferably 0.5 to 5 mm from the viewpoints of mechanical strength and handleability. The apparent weight (apparent weight as a whole) of the fiber laminate is from 5.5 to 120 g / m 2, and more preferably from 10 to 60 g / m 2 or more from the viewpoint of the collection performance, the mechanical strength and the handling property. The density (total density (bulk density)) of the fiber laminate is preferably 0.005 to 0.5 g / cm 3, more preferably 0.01 to 0.2 g / cm 3, further preferably 0.1 g / cm 3 or less (for example, 0.01 to 0.1 g / cm 3).

The air permeability of the fiber laminate is preferably 80 to 1000 cc / cm2 / s, more preferably 100 cc / cm2 / s or more (for example, (For example, 100 to 800 cc / cm 2 / s), and more preferably 110 to 500 cc / cm 2 / s (for example, 120 to 400 cc / cm 2 / s). If the air permeability of the fiber laminate is excessively high, it is difficult to obtain sufficient collection performance.

The fiber laminate related to this embodiment can be preferably used as a filter medium, for example, and the collection efficiency measured in accordance with JIS T 8151 can be 85% or more, and more than 90%. In addition, the pressure loss measured in accordance with JIS T 8151 of the fiber laminate related to the present embodiment may be 10 Pa or less, more preferably 5 Pa or less. In addition, the fiber laminate according to the present embodiment can have a QF value of not less than 0.6, more preferably not less than 0.8, and further not less than 0.9 (for example, not less than 1), which indicates the filter material performance. The definition of the QF value is as described in the section of the embodiment.

The fiber laminate is obtained by forming fibers (preferably thin) for forming a second fiber aggregate on the first main surface 11 of a previously prepared first fiber aggregate (first fiber layer 1) by melt blowing or the like, Can be produced by spraying. According to this method, the group of fibers sprayed on the first main surface 11 is solidified on the first main surface 11 in a state of tightly adhering to the surface of the first main surface 11 ) And the second fiber layer (2) can be obtained. Thereby, as described above, a separate heat-sealing step such as thermal embossing or an adhering step using an adhesive or the like becomes unnecessary. The bonding of the first fibrous layer 1 and the second fibrous layer 2 by heat fusion or the presence of the intervening layer such as an adhesive tends to lower the air permeability of the fiber laminate.

A second fiber aggregate (second fiber layer 2) (preferably thin) is formed on the first main surface 11 of the previously prepared first fiber aggregate (first fiber layer 1) by a melt blow method or the like The first surface irregularities and the second surface irregularities of the second fibrous layer 2 often reflect the first surface irregularities. However, the shapes of the first surface irregularities and the second surface irregularities of the second fibrous layer 2 need not necessarily reflect the first surface irregularities in all of them.

The fiber laminates according to the present invention may be those that have been subjected to a charging treatment (provided with charging property) in order to further improve the collecting performance. The term "electrification" refers to a state in which the fiber laminate is electrically charged, and preferably the surface charge density (value obtained by dividing the amount of charge measured by using a Faraday cage [electrostatic charge amount meter] by the measurement area) is 1.0 × 10 ^-10 Cm 2 or more, more preferably 1.5 x 10 ^-10 coulombs / cm 2 or more, and even more preferably 2.0 x 10 ^-10 coulombs / cm 2 or more.

Examples of a method of imparting chargeability to the fiber laminate include a method of imparting charge by friction or contact, a method of irradiating an active energy ray (for example, electron beam, ultraviolet ray, X ray or the like), a corona discharge, A suitable electretization treatment such as a method using a gas discharge, a method using a high electric field, and a hydrocharging method using a polar solvent such as water. Among them, the corona discharge method and the hydro-charging method are preferable because a high charging property can be obtained with a relatively low electric power amount, and the hydro-charging method is more preferable because uniform charging property can be given in the thickness direction.

In the hydrocharging method, for example, a polar solvent such as water or an organic solvent (preferably water from the standpoint of productivity such as a wastewater treatment) is charged by spraying or spraying on a fiber laminate, thereby charging the fiber laminate. The pressure of the polar solvent impinging on the fiber laminate is preferably 0.1 to 5 MPa, more preferably 0.5 to 3 MPa, and the suction pressure from the lower portion is preferably 500 to 5000 mmH ₂ O, Lt; ₂ > The treatment time of hydrocharging is preferably 0.01 to 5 seconds, more preferably 0.02 to 1 second. The charged fiber laminate after the hydro-charging method is preferably dried at a temperature of, for example, 40 to 100 캜, preferably 50 to 80 캜.

The apparatus and conditions used in the corona discharge method are not particularly limited. For example, by using a DC high voltage stabilized power source, for example, a linear distance between electrodes to which a voltage is applied is 5 to 70 mm (preferably 10 to 30 mm ), An applied voltage of -50 to -10 kV and / or 10 to 50 kV (preferably -40 to -20 kV and / or 20 to 40 kV) Is 30 to 80 DEG C) and the treatment time is 0.1 to 20 seconds (preferably 0.5 to 10 seconds).

The fiber laminate related to this embodiment can be preferably used as a filter medium. Specific examples of the filter medium include a mask for a human being, an industrial filter medium (for example, an industrial air filter medium).

(Other Embodiments)

2 to 5, a fiber laminate according to another embodiment of the present invention will be described. In the following, only the points different from the fiber laminate shown in Fig. 1 will be described, and the above description of the first embodiment is cited in other respects.

The fibrous laminate shown in Fig. 2 has a structure in which the second main surface 12 of the first fibrous layer 1 is composed of a relatively smooth surface (for example, a surface having a convex portion height of less than 0.1 mm) And has the same structure as the fiber laminate.

As shown in Fig. 3, the first surface irregularities of the first fiber layer 1 and the first surface irregularities of the second fibrous layer 2 need not be in contact with the entire surface, 2 fibrous layer 2 may have a portion where they are not in contact with each other. For example, first surface irregularities are formed on at least a part of the first main surface 21 of the second fibrous layer 2, and the first surface irregularities and the first surface irregularities of the second fibrous layer 2 And the like.

As described above, in the present invention, at least one of the first main surface 11 of the first fibrous layer 1 and the first main surface 21 of the second fibrous layer 2 may have a first surface irregularity , For example, as shown in Fig. 4, only the first fiber layer 1 has the first surface irregularities, or only the second fiber layer 2 has the first surface irregularities as shown in Fig. 5 .

Also in the above-described embodiment, it is possible to combine high air permeability and high collection performance as in the first embodiment.

Example

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited by these Examples. In the following Examples and Comparative Examples, the measurement methods of the respective physical properties are as follows.

[1] Apparent weight (g / m 2)

The apparent weight as a whole of the fiber laminate and the apparent weight of each layer of the first fiber layer and the second fiber layer were measured in accordance with JIS L 1913 "General Nonwoven Fabric Test Method".

[2] Thickness (mm)

Using a tabletop microscope ("Miniscope TM3030" manufactured by Hitachi High-Technologies Corporation), 50 times of the cross section of the fiber laminate was photographed. For the exposure of the cross section, the fiber laminate was cut by pressing it from the top down using a cutter (without cutting the fiber laminate and then turning the cutter from the bottom up). The distance in the thickness direction from the convex peak of the second surface irregularities of the second fibrous layer to the back surface of the fiber laminate (the second main surface of the first fibrous layer, the convex vertex in the case of irregularities, etc.) The thickness of the fiber laminate was measured at 10 locations (where two neighboring locations had an interval of 1 mm). The average value of these was taken as " thickness of the fiber laminate. &Quot; Further, based on the above photograph, from the top of the convex portion of the first surface irregularities (first main surface) of the first fibrous layer to the back surface of the fiber laminate (the second main surface of the first fibrous layer, Were measured for arbitrary 10 points in the thickness direction (the two neighboring two points had an interval of 1 mm), and the average value of these was taken as the " thickness of the first fiber layer ". The thickness of the first fibrous layer was subtracted from the thickness of the fibrous laminate to obtain the thickness of the second fibrous layer.

[3] Density (bulk density) (g / cm 3)

The apparent weight value obtained in the above [1] was divided by the thickness obtained in the above [2] to obtain the density as a whole of the fiber laminate, and the density of each layer of the first fiber layer and the second fiber layer.

[4] Height of convex portion (mm)

From the surface of the first fibrous layer excluding the convex portions of the first surface irregularities to the back surface of the fiber laminate (the second main surface of the first fibrous layer, the convex apex when there is irregularity) The thickness direction distances were measured at arbitrary 5 points (however, two neighboring two points had an interval of 1 mm), and the average value of these was obtained. The average value was subtracted from the " thickness of the first fiber layer " obtained in the above [2] to obtain the height of the convex portion of the first surface irregularities in the first fiber layer.

Further, based on the photograph obtained in the above [2], it is possible to determine the distance from the surface of the second fibrous layer excluding the convexities of the first surface irregularities (surface irregularities on the first fibrous layer side) to the convex apexes of the second surface irregularities of the second fibrous layer The thickness direction distances were measured at arbitrary 5 points (however, two neighboring two points had an interval of 1 mm), and the average value of these was obtained. The average value was subtracted from the " thickness of the second fiber layer " obtained in the above [2] to obtain the height of the convex portion of the first surface irregularities in the second fiber layer.

The " height of the convex portion of the second surface irregularities " in the second fiber layer is measured as follows. From the surface of the second fiber layer excluding the convex portion of the second surface irregularities to the back surface of the fiber laminate (the second main surface of the first fiber layer, the convex portion apex when there is irregularity) The thickness direction distances are measured at arbitrary five points (however, two neighboring two points have an interval of 1 mm), and an average value of these is obtained. The average value is subtracted from the "thickness of the fiber laminate" obtained in the above [2] to obtain the "height of the convex portion of the second surface irregularities" in the second fiber layer.

[5] Density of convex portion (number / cm2)

Using a tabletop microscope (" Miniscope TM3030 " manufactured by Hitachi High-Technologies Corporation), a 50-fold picture of the cross section parallel to the MD direction of the fiber laminate was taken. For the exposure of the cross section, the fiber laminate was cut by pressing it from the top down using a cutter (without cutting the fiber laminate and then turning the cutter from the bottom up). The thickness direction distances from the convex apexes of the first surface irregularities of the first fiber layer to the back surface of the fiber laminate (the second main surface of the first fiber layer and the convex portion apex when there is unevenness) And the two neighboring ones have an interval of 1 mm), and a line perpendicular to the thickness direction is drawn at a position of a gap (height) of 1/3 of the average value of these. The number of convex portions protruding from this line per 1 cm was defined as " number of MD convex portions ". The same measurement was made also for a section parallel to the CD direction to obtain " number of CD convex portions ". The density of the convex portion of the first surface irregularities in the first fiber layer was obtained as the product of the number of "MD convex portions" and the number of "CD convex portions".

Further, based on the photographs obtained above, the thickness direction distance from the convex peak of the first surface irregularities of the second fibrous layer to the second main surface of the second fibrous layer (the surface except the convex portions when irregularities are present) The density of the convex portion of the first surface irregularities in the second fiber layer was obtained in the same manner as described above except that the measurement was performed with respect to each of the two neighboring two sites (each having an interval of 1 mm) .

The " density of the convex portion of the second surface irregularities " in the second fiber layer is measured as follows. The thickness direction distances from the convex apexes of the second surface irregularities of the second fibrous layer to the first main surface of the second fibrous layer (the surface excluding the convex portions when the irregularities are present) are arbitrary 10 points Are measured with respect to the thickness direction), and a line perpendicular to the thickness direction is drawn at the position of the interval (height) of 1/3 of the average value of these. The number of convex portions protruding from this line per 1 cm is defined as " number of MD convex portions ". The same measurement is made also for a cross section parallel to the CD direction to obtain " number of CD convex portions ". The density of the convex portion of the second surface irregularities in the second fiber layer is obtained as the product of the number of "MD convex portions" and the number of "CD convex portions".

[6] Average fiber diameter (占 퐉)

Using a scanning electron microscope (" Miniscope TM3030 " manufactured by Hitachi High-Technologies Corporation), a photograph of a 500-fold magnification of the surfaces of the first and second fiber layers was taken. The diameter of any 100 fibers in the photograph was measured and the average value of these fibers was taken as the average fiber diameter. However, since the fiber diameter of the fused fiber can not be clearly measured, it was excluded.

[7] Ventilation performance

The air permeability (cc / cm 2 / s) of the fiber laminate was measured in accordance with the Przire method of JIS L 1913 "General nonwoven fabric test method".

[8] Capture performance

[8-1] Collection efficiency (%) and pressure loss (Pa)

According to JIS T 8151, the fiber layered product was cut into a size of 11 cmφ, and the filter layer was set on a sample bed of 8.6 cmφ (filtration area: 58.1 cm 2) at an air flow rate of 20 L / min and a surface velocity of 5.7 cm / (%) And pressure loss (Pa) when the NaCl particles (average particle diameter: 0.1 mu m) were filtered were measured.

[8-2] QF value

From the collection efficiency and pressure loss obtained in the above [8-1], the following formula:

QF value = -ln (1-collecting efficiency (%) / 100) / pressure loss (Pa)

The QF value was calculated.

≪ Example 1 >

The melt flow of polypropylene (MFR (230 占 폚, 21.18 N load) = 30 g / 10 min) was ejected from the nozzle hole by melt extrusion and the filament flow, which was refined by hot air, was collected on a roll wound on a conveyor net, To obtain a first fibrous aggregate (first fibrous layer) having an apparent surface weight of 20.0 g / m < 2 > having a first surface irregularity which is a blown nonwoven fibrous aggregate. Specific conditions of the melt blowing method are as follows.

Hole diameter: 0.4 mm,

Hole interval: 1.50 mm,

Radiation temperature: 260 占 폚,

· Single hole discharge rate: 0.3 g / min · Hole,

· Temperature of spouting hot air: 260 ° C,

· Flow rate of blowing hot air: 13 Nm 3 / min (1 m)

· Distance from nozzle to conveyor net: 32 cm,

· Types of conveyor nets: Balance type (width pitch 5 mm × length pitch 5 mm × thickness 5 mm, 1 mmφ).

Next, the first surface irregularities of the first fibrous layer were coated with a first surface irregularity layer of melt blown nonwoven fabric aggregate on the first surface irregularities using polypropylene (MFR (230 ° C, 21.18 N load) = 700 g / And a second fiber aggregate (second fiber layer) having an apparent surface weight of 2.7 g / m < 2 > having a second surface irregularity were formed to obtain a fiber laminate.

Hole diameter: 0.3 mm,

Hole interval: 0.75 mm,

Radiation temperature: 215 占 폚,

· Single hole discharge amount: 0.036 g / min · Hole,

Temperature of the blowing hot air: 215 ° C,

Flow rate of the blowing hot air: 10 Nm 3 / min (1 m)

Distance from the nozzle to the conveyor net: 11 cm.

A table-top microscope photograph of one end surface of the fiber laminate obtained in Example 1 is shown in Fig. It can be seen that the first fiber layer has the first surface irregularities and the second fiber layer has the first surface irregularities and the second surface irregularities. The projections constituting the first surface irregularities were convex portions in the form of bristles (the same applies in Examples 2 to 6).

Next, the obtained fiber laminate was subjected to a charging treatment by the hydro-charging method. The specific conditions of the hydrocharging method are as follows.

· Solvents used: water,

· Water pressure: 0.4 MPa,

Suction pressure: 2000 mmH ₂ O,

Processing time: 0.042 sec (processing width 14 mm, speed 20 m / min).

≪ Example 2 >

A first fiber aggregate (first fiber layer) was obtained in the same manner as in Example 1 except that the distance from the nozzle to the conveyor net was changed to 15 cm and the apparent weight was 15.0 g / m 2. Thereafter, a fiber laminate was produced in the same manner as in Example 1.

≪ Example 3 >

Except that the type of the conveyor net was changed to a balance type (2.5 mm wide pitch x 3 mm long pitch 4 mm, 0.8 mm phi), and the distance from the nozzle to the conveyor net was changed to 20 cm. 1, a first fibrous aggregate (first fibrous layer) was obtained. Thereafter, a fiber laminate was produced in the same manner as in Example 1.

<Example 4>

A fiber laminate was produced in the same manner as in Example 2 except that the apparent weight of the first fiber layer was 10 g / m 2.

&Lt; Example 5 &gt;

A first fiber aggregate (first fiber layer) was obtained in the same manner as in Example 3 except that the distance from the nozzle to the conveyor net was changed to 25 cm and the apparent weight was 30.0 g / m 2. Thereafter, a fiber laminate was produced in the same manner as in Example 3.

&Lt; Example 6 &gt;

A fiber laminate was produced in the same manner as in Example 1 except that in the formation of the second fiber layer, the distance from the nozzle to the conveyor net was changed to 40 cm. In this fiber laminate, the convex portion of the first main surface (first fiber layer side surface) of the second fiber layer had a height of 0.005 mm at the maximum.

&Lt; Comparative Example 1 &

A fiber laminate was produced in the same manner as in Example 1, except that in the formation of the first fiber layer, the kind of the conveyor net was changed to a 200 mesh plain weave stainless steel wire mesh. The convexities of the first main surface (second fibrous layer side surface) of the first fibrous layer and the first main surface (first fibrous layer side surface) of the second fibrous layer of the fiber laminate are 0.005 mm at the maximum, The pressure loss was higher and the QF value was higher than that of the fiber laminate of Examples.

The above-mentioned [1] to [8] were measured for the fiber laminates obtained in Examples and Comparative Examples. The results are shown in Table 1. In addition, the air permeability, the collection efficiency, the pressure loss and the QF value are values after the charging treatment.

1: first fiber layer
2: second fibrous layer
11: First main surface of the first fibrous layer (main surface on the second fibrous layer side)
12: a second main surface of the first fibrous layer (main surface opposite to the second fibrous layer)
21: the first main surface of the second fibrous layer (main surface on the first fibrous layer side)
22: second main surface of the second fibrous layer

Claims (15)

A first fiber layer having a first major surface and composed of a first fiber aggregate,
And a second fibrous layer composed of a second fibrous aggregate, the fibrous layer being disposed on the first main surface,
At least one of the first main surface and the main surface on the first fibrous layer side of the second fibrous layer has a first surface irregularity,
And the height of the convex portion constituting the first surface irregularities is 0.1 mm or more. The method according to claim 1,
Wherein the density of the convex portions constituting the first surface irregularities is 3 / cm &lt; 2 &gt; or more. 3. The method according to claim 1 or 2,
At least the first major surface has the first surface irregularities. 4. The method according to any one of claims 1 to 3,
Wherein a major surface of the second fibrous layer opposite to the first fibrous layer has a second surface irregularity and the height of the convex portion constituting the second surface irregularities is 0.05 mm or more. 5. The method of claim 4,
And the density of the convex portions constituting the second surface irregularities is 3 / cm &lt; 2 &gt; or more. 6. The method according to any one of claims 1 to 5,
And a bulk density of 0.1 g / cm &lt; 3 &gt; or less. 7. The method according to any one of claims 1 to 6,
Wherein a ratio T ₁ / T ₂ of a thickness T ₁ of the first fiber layer to a thickness T ₂ of the second fiber layer is 4 to 25. 8. The method according to any one of claims 1 to 7,
Wherein the first fibrous aggregate and the second fibrous aggregate are non-woven fibrous aggregates. 9. The method of claim 8,
Wherein the nonwoven fabric aggregate comprises a polyolefin-based resin fiber. 10. The method according to any one of claims 1 to 9,
Wherein the fibers constituting the second fibrous aggregate have an average fiber diameter of 0.5 to 2 占 퐉. 11. The method according to any one of claims 1 to 10,
Wherein the air permeability is not less than 100 cc / cm 2 / s. 12. The method according to any one of claims 1 to 11,
A collecting efficiency and a pressure loss measured according to JIS T 8151 are 85% or more and 10 Pa or less, respectively, and the following formula:
QF value = -ln (1-collecting efficiency (%) / 100) / pressure loss (Pa)
Wherein a QF value calculated according to the following formula is 0.6 or more. 13. The method according to any one of claims 1 to 12,
Treated fiber bundle. 14. The method according to any one of claims 1 to 13,
A fibrous laminate, which is a filter medium. 14. The method according to any one of claims 1 to 13,
A cleaning article, fiber laminate.

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