JPWO2017018317A1 - Fiber laminate - Google Patents

Abstract

A first fiber layer having a first main surface and configured by a first fiber assembly, and a fiber layer disposed on the first main surface and configured by a second fiber assembly. The height of the convex part which comprises a fiber layer and at least any one of the 1st main surface by the side of the 1st fiber layer in a 1st main surface and a 2nd fiber layer has 1st surface unevenness | corrugation A fiber laminate having a thickness of 0.1 mm or more is provided.

Description

  The present invention relates to a fiber laminate that can be suitably used as a filter medium or the like.

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

  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 μm and a thickness of 0.03 to 0.1 mm, and an average fiber diameter of 5 It has a two-layer structure composed of a fiber layer B which is a polyolefin fiber layer having a thickness of ˜60 μm and a thickness of 0.15 to 1.5 mm, and the density, the thickness ratio of the fiber layer A and the fiber layer B, and A laminate for an air filter medium having an air permeability within a predetermined range is disclosed. According to the description in Patent Document 1, this laminate has high air permeability and collection efficiency.

Japanese Patent No. 5205650

  An object of the present invention is to improve the ventilation performance and collection performance of a fibrous body that can be used as a filter medium.

The present invention provides the following fiber laminate.
[1] A first fiber layer having a first main surface and composed of a first fiber assembly;
A fiber layer disposed on the first main surface, the second fiber layer comprising a second fiber assembly;
Including
At least one of the first main surface and the main surface on the first fiber layer side in the second fiber layer has first surface irregularities,
The fiber laminated body whose height of the convex part which comprises the said 1st surface unevenness | corrugation is 0.1 mm or more.

[2] The fiber laminate according to [1], wherein the density of the convex portions constituting the first surface irregularities is 3 pieces / 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 main surface of the second fiber layer opposite to the first fiber layer has second surface irregularities, and the height of the convex portions constituting the second surface irregularities is 0.05 mm or more. , [1] to [3] The fiber laminate according to any one of [3].

[5] The fiber laminate according to [4], wherein the density of the convex portions constituting the second surface irregularities is 3 pieces / 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 ratio T ₁ / T ₂ of the thickness T ₁ of the first fiber layer and the thickness T ₂ of the second fiber layer is 4 to 25, according to any one of [1] to [6]. Fiber laminate.

  [8] The fiber laminate according to any one of [1] to [7], wherein the first fiber assembly and the second fiber assembly are non-woven fiber assemblies.

  [9] The fiber laminate according to [8], wherein the nonwoven fiber aggregate includes polyolefin resin fibers.

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

[11] The fiber laminate according to any one of [1] to [10], which has an air permeability of 100 cc / cm ² / s or more.

[12] The collection efficiency and pressure loss measured in accordance with JIS T 8151 are 85% or more and 10 Pa or less, respectively, and the following formula:
QF value = -ln (1-collection efficiency (%) / 100) / pressure loss (Pa)
The fiber laminate according to any one of [1] to [11], wherein the QF value calculated according to the above is 0.6 or more.

[13] The fiber laminate according to any one of [1] to [12], which is charged.
[14] The fiber laminate according to any one of [1] to [13], which is a filter medium.

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

  ADVANTAGE OF THE INVENTION According to this invention, the fiber body which is excellent in ventilation | gas_flowing performance and collection performance can be provided. The fiber body (fiber laminate) according to the present invention is suitable for filter media such as air filter media and masks.

It is a schematic sectional drawing which shows an example of the fiber laminated body which concerns on 1st Embodiment of this invention. It is a schematic sectional drawing which shows an example of the fiber laminated body which concerns on 2nd Embodiment of this invention. It is a schematic sectional drawing which shows an example of the fiber laminated body which concerns on 3rd Embodiment of this invention. It is a schematic sectional drawing which shows an example of the fiber laminated body which concerns on 4th Embodiment of this invention. It is a schematic sectional drawing which shows an example of the fiber laminated body which concerns on 5th Embodiment of this invention. 1 is a tabletop micrograph of a cross section of a fiber laminate according to Example 1.

  The present invention includes a first fiber layer having a first main surface and configured by a first fiber assembly, and a fiber layer disposed on the first main surface, and configured by a second fiber assembly. At least one of the first main surface (inner main surface) of the first fiber layer and the first main surface (inner main surface) of the second fiber layer on the first fiber layer side. The present invention relates to a fiber laminate having surface irregularities. Hereinafter, the present invention will be described in detail with reference to embodiments.

(First embodiment)
FIG. 1 is a schematic cross-sectional view showing an example of a fiber laminate according to the first embodiment of the present invention. The fiber laminate shown in FIG. 1 includes a first fiber layer 1 composed of a first fiber assembly, and a second fiber layer disposed on the first main surface 11 and composed of a second fiber assembly. 2 is included. The first fiber layer 1 includes a first main surface (inner main surface) 11 that is a main surface on the second fiber layer 2 side, and a second main surface that is opposite to the second fiber layer 2 and that is opposite to the second fiber layer 2. Main surface (outer main surface) 12. The second fiber layer 2 includes a first main surface (inner main surface) 21 that is a main surface on the first fiber layer 1 side and a second main surface that is opposite to the first fiber layer 1 and that is opposite to the first fiber layer 1. And a main surface (outer main surface) 22.

  The 1st main surface 11 of the 1st fiber layer 1 is constituted by surface unevenness, and the 2nd fiber layer 2 is laminated on it. The second fiber layer 2 is in contact with the first main surface 11 of the first fiber layer 1 over the entire surface or substantially the entire surface. Accordingly, the first main surface 21 of the second fiber layer 2 also has surface unevenness that is a transfer type (or approximately transfer type) of the surface unevenness of the first main surface 11 of the first fiber layer 1. That is, the interface between the first fiber layer 1 and the second fiber layer 2 is constituted by irregularities. In this specification, the surface unevenness | corrugation which the 1st main surface 11 of the 1st fiber layer 1 and / or the 1st main surface 21 of the 2nd fiber layer 2 may have is named generically, and it is also called "the 1st surface unevenness | corrugation."

  In the fiber laminate shown in FIG. 1, the second fiber layer 2 also has surface irregularities on the second main surface 22. In the present specification, the surface unevenness that the second main surface (outer main surface) 22 of the second fiber layer 2 may have is also referred to as “second surface unevenness”. In the fiber laminate shown in FIG. 1, the first fiber layer 1 also has surface irregularities on its second main surface 12. In the present specification, the surface unevenness that the second main surface (outer main surface) 12 of the first fiber layer 1 may have is also referred to as “third surface unevenness”.

  As illustrated by the fiber laminate shown in FIG. 1, the fiber laminate according to the present embodiment (the same applies to other embodiments described later) includes the first main surface 11 and the second main surface 11 of the first fiber layer 1. One feature is that at least one of the first principal surfaces 21 of the fiber layer 2 has first surface irregularities. The fiber laminate according to the present embodiment can have both high ventilation performance and high collection performance. The fiber laminate according to the present embodiment can be suitably used for filter media such as air filter media and masks. When the fiber laminate according to the present embodiment is applied to, for example, a human mask, it has high ventilation performance (low pressure loss), so that it is difficult to feel breathlessness and long-term wearability (even if worn for a long time). It excels in the sense of discomfort such as breathlessness) and has high collection performance, so it effectively collects foreign substances in gases such as viruses, dust, dust, house dust, pollen, and yellow sand. Can do. Also, for example, when applied to industrial air filter media, it has high ventilation performance, so it can increase the processing speed of filtration (foreign matter removal) and has high collection performance, so that it can be used for dust, dust, etc. Foreign matter in the air can be collected with high collection efficiency and / or with high collection capacity.

  In addition, the fiber laminate according to the present embodiment (the same applies to other embodiments described later) uses the second surface unevenness of the second main surface 22 of the second fiber layer 2 to make a human body, clothing, and the like. For example, it can be used as a cleaning tool typified by a wiper for removing foreign substances attached to an article as described above.

  In the present invention, the main surface having the first surface unevenness only needs to have the first surface unevenness in at least a part thereof, and it is not necessary that all of the main surfaces are constituted by the first surface unevenness. The same applies to the second and third surface irregularities. However, from the viewpoint of further improving the ventilation performance and the collection performance, it is preferable that the main surface having the first surface irregularities is (or approximately all) of the first surface irregularities. The same applies to the second and third surface irregularities.

Hereinafter, the fiber laminate according to the present embodiment (first embodiment) will be described in more detail.
(1) 1st fiber layer The 1st fiber layer 1 is a layer comprised by the 1st fiber aggregate, and the 1st principal surface (inner principal surface) 11 (major surface by the side of the 2nd fiber layer 2) is the 1st. The second main surface (outer main surface) 12 has third surface unevenness. The first major surface 11 is preferably composed of first surface irregularities, and the second major surface 12 is preferably composed of third surface irregularities. The first surface unevenness of the first main surface 11 is a surface forming an interface with the second fiber layer 2 (therefore, the first main surface 21 of the second fiber layer also has the first surface unevenness). When the interface of a layer is comprised by an unevenness | corrugation, the collection performance and ventilation performance of a fiber laminated body can be improved. In addition, having the third surface irregularities is advantageous for further improving the collection performance and ventilation performance. The convex part which the 1st main surface (inner main surface) 11 and the 2nd main surface (outer main surface) 12 have may exist regularly, and may exist 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, or a raised shape.

From the viewpoint of improving the collection performance of the fiber laminate, the height of the convex portions constituting the first surface irregularities of the first main surface (inner main surface) 11 is 0.1 mm or more, preferably 0.2 mm. It is above, More preferably, it is 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 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 collection performance is not recognized or insufficient. When the convex portion is too high, it is disadvantageous in terms of mechanical strength of the fiber laminate. Further, from the viewpoint of improving the collection performance of the fiber laminate, the density of the convex portions in the first surface irregularities is preferably 3 pieces / cm ² or more, and more preferably 10 pieces / cm ² or more. The density of the convex portions is usually 50 pieces / cm ² or less, and typically 30 pieces / cm ² or less. If the density of the convex portions is excessively large, the air permeability of the fiber laminate may be adversely affected. The height and density of the protrusions are measured according to the method described in the example section using a tabletop microscope. The height and density of the convex portions constituting the third surface irregularities can be the same as the height and density of the convex portions constituting the first surface irregularities of the first fiber layer 1, respectively.

  Although the 1st fiber assembly which comprises the 1st fiber layer 1 may be comprised with the woven fabric, it is preferable that it is a non-woven fiber assembly. Among these, the first fiber aggregate is more preferably a melt blown nonwoven fiber aggregate. By using the melt-blowing method, it is possible to easily and inexpensively manufacture a nonwoven fiber assembly having a small bulk density and excellent air permeability and having first surface irregularities and further third surface irregularities. A general melt blow spinning apparatus can be used for the melt blow method.

  When using the melt blow method, the 1st fiber layer 1 is manufactured as a fiber web obtained by collecting the fiber flow injected from the nozzle with the uneven surface of a collection body. That is, when the fibers enter and solidify into the recesses (or the penetrating portions) of the collection surface, irregularities are imparted to one main surface or both main surfaces of the first fiber assembly. The collector can be a metal collector provided with a plurality of (or many) convex portions or concave portions, a metal mesh having a mesh, a cloth cloth, or the like. Among them, it is preferable to use a net having a three-dimensional structure generally called a conveyor net, whereby a non-woven fiber assembly having first surface unevenness and further third surface unevenness can be more easily manufactured.

  The raised portion constituting the first surface irregularities may be a raised protrusion. The raised protrusions are preferably rigid. When a net such as a conveyor net is used as the collecting body, the convex portion tends to be a raised protrusion. As will be described later, the fiber laminate is sprayed on the first main surface 11 of the first fiber aggregate (first fiber layer 1) prepared in advance by the fibers forming the second fiber aggregate by the melt blow method or the like. Although it can be manufactured, if the convex portion constituting the first surface irregularity is a raised projection, the bonding strength between the first fiber layer 1 and the second fiber layer 2 is increased, and thereby the fiber laminate. Can increase the durability.

  The average fiber diameter (first average fiber diameter) of the fibers constituting the first fiber aggregate is preferably 5 to 50 μm, more preferably 7 to 25 μm. When the first average fiber diameter is within this range, the first fiber aggregate (first fiber) has a rigidity sufficient to maintain the shape of the first surface unevenness and further the third surface unevenness even after the fiber laminate is formed. Can be applied to layer 1). Further, setting the first average fiber diameter in the above range is advantageous in improving the balance between the ventilation performance and the collection performance of the fiber laminate. If the first average fiber diameter is too small, the ventilation performance tends to deteriorate. If the first average fiber diameter is too large, the collection performance tends to be lowered.

The fibers constituting the first fiber assembly usually include fibers made of a thermoplastic resin. Specific examples of thermoplastic resins include polyolefin resins (low density, medium density or high density polyethylene, poly C _2-4 olefin resins such as polypropylene); styrene resins (heat resistant polystyrene, etc.); polyester resins ( Polyethylene terephthalate resin, polytrimethylene terephthalate resin, polybutylene terephthalate resin, poly C _2-4 alkylene arylate resin such as polyethylene naphthalate resin, etc.); polyamide resin (polyamide 6, polyamide 66, polyamide 11, polyamide 12, Aliphatic polyamide resins such as polyamide 610 and polyamide 612, semiaromatic polyamide resins, polyphenylene isophthalamide, polyhexamethylene terephthalamide, and aromatic polyamides such as poly p-phenylene terephthalamide De resins); polycarbonate resin (bisphenol A polycarbonate); including cellulose resin (cellulose ester); polyurethane resin. Among these, polyolefin resins, polyester resins, and polyamide resins are preferably used, and polyolefin resins are more preferably used. The fibers constituting the first fiber assembly may contain two or more kinds of thermoplastic resins.

  Among the polyolefin resins, polypropylene is preferably used. A polyolefin-based resin, particularly polypropylene, can be easily charged by a charging process described later, so that a fiber laminate having a higher filtration performance (collecting performance) by charging can be obtained more easily. When the fiber which comprises a 1st fiber assembly contains a polypropylene, the said fiber may be comprised only with the polypropylene and may contain thermoplastic resins other than a polypropylene. In the latter case, the content of polypropylene is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more.

  The fibers constituting the first fiber aggregate are conventional additives such as stabilizers (heat stabilizers, ultraviolet absorbers, light stabilizers, antioxidants, etc.), antibacterial agents, deodorants, fragrances, and colorants. (Dyes and pigments), fillers, antistatic agents, flame retardants, plasticizers, lubricants and the like may be contained. Only 1 type may be used for an additive and it may use 2 or more types together. The additive may be supported on the fiber surface or may be contained in the fiber.

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

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

  In the case where the first fiber aggregate is a melt blown nonwoven fiber aggregate, the first fibers exhibiting rigidity sufficient to maintain the shape of the first surface irregularities and further the third surface irregularities even after the fiber laminate is formed. In order to form an aggregate, it is preferable that the fibers reach the collection surface in a thick state before the fibers of the meltblown fiber stream are thinned and before the fibers are solidified. Since it is necessary to cleanly peel off the uneven collecting surface after the fiber flow is solidified, it may be necessary to cool the collecting surface.

  Further, in order to form the first fiber aggregate exhibiting the above-described rigidity, the fiber is solidified by increasing the fiber diameter by shortening the collection distance of the fiber flow or increasing the resin viscosity. It is preferable to lengthen the time until. The collection distance is, for example, 5 to 100 cm, and preferably 10 to 60 cm. The resin viscosity is, for example, 10 to 100 Pa · s, preferably 20 to 50 Pa · s, although it depends on the resin used and the melting temperature.

The basis weight W ₁ of the first fiber layer 1 (first fiber aggregate) is preferably 5 to 100 g / m ² from the viewpoint of ventilation performance and collection performance (foreign material collection efficiency and / or collection capacity). Yes, more preferably 10 to 50 g / m ² or more. If the basis weight W ₁ is too small, it is difficult to obtain sufficient filtration performance. If the basis weight W ₁ is too large, it is difficult to obtain good ventilation performance. 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 and more preferably 0.01 to 0.2 g from the viewpoint of air permeability. / Cm ³ . If the density D ₁ is too large, the ventilation performance may be reduced. If the density D ₁ is too small, sufficient filtration performance is difficult to obtain, and the mechanical strength of the fiber laminate may be reduced.

The thickness T ₁ of the first fiber layer 1 in the fiber laminate is preferably 0.3 to 5 mm, more preferably, from the viewpoints of ventilation performance and collection performance (foreign material collection efficiency and / or collection capacity). Is 0.4 to 3 mm. By setting the thickness T ₁ in the above range, it becomes easy to obtain the first fiber layer 1 exhibiting the above-described rigidity, and good ventilation performance and collection performance (including collection capacity) can be obtained. .

From the viewpoint of the balance between the ventilation performance and the collection performance, the air permeability of the first fiber layer 1 (first fiber aggregate) is the air permeability according to the Frazier method, preferably 100 to 1000 cc / cm ² / s. More preferably, it is 110-800 cc / cm < ² > / s, More preferably, it is 120-500 cc / cm < ² > / s (for example, 130-400 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 be insufficient. If the air permeability of the first fiber layer 1 is too high, it is difficult to obtain sufficient collection performance.

(2) 2nd fiber layer The 2nd fiber layer 2 is a layer comprised by a 2nd fiber assembly, and the 1st main surface (inner main surface) 21 (main surface by the side of the 1st fiber layer 1) is the 1st. The first main surface (outer main surface) 22 can have second surface unevenness. The first main surface 21 is preferably made of first surface unevenness, and the second main surface 22 is preferably made of second surface unevenness. From the viewpoint of improving the collection performance and ventilation performance of the fiber laminate, it is preferable that at least the first main surface 11 of the first fiber layer 1 has first surface irregularities as in the present embodiment, and the first fiber layer It is more preferable that both the first main surface 11 of 1 and the first main surface 21 of the second fiber layer 2 have first surface irregularities. Moreover, when the 2nd main surface 22 of the 2nd fiber layer 2 has 2nd surface unevenness | corrugation, it will become advantageous to the improvement of collection performance and ventilation | gas_flowing performance. The convex portions of the first main surface (inner main surface) 21 and the second main surface (outer main surface) 22 of the second fiber layer 2 may exist regularly or randomly. Good. 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, or a raised shape.

  About the height and density of the convex part which the 1st main surface (inner main surface) 21 of the 2nd fiber layer 2 has about the convex part which the 1st main surface (inner main surface) 11 of the 1st fiber layer 1 has The above description is cited.

From the viewpoint of improving the collection performance of the fiber laminate, the height of the convex portions 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. More preferably, it is 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 too low and its height is less than 0.05 mm and the second main surface 22 is smooth, improvement in the collection performance is not recognized or insufficient. When the convex portion is too high, it is disadvantageous in terms of mechanical strength of the fiber laminate. Further, from the viewpoint of enhancing the collection performance of the fiber laminate, the density of the convex portions in the second surface irregularities is preferably 3 pieces / cm ² or more, and more preferably 10 pieces / cm ² or more. The density of the convex portions is usually 50 pieces / cm ² or less, and typically 30 pieces / cm ² or less. If the density of the convex portions is excessively large, the air permeability of the fiber laminate may be adversely affected.

  Although the 2nd fiber assembly which comprises the 2nd fiber layer 2 may be comprised with the woven fabric, Preferably it is a nonwoven fiber assembly. Among these, the second fiber aggregate is more preferably a melt blown nonwoven fiber aggregate. According to the melt-blowing method, the second fiber assembly (second fiber layer 2) made of fibers having a desired average fiber diameter is subjected to a bonding process using a separate heat-sealing process such as hot embossing or an adhesive. Without carrying out, it becomes easy to laminate on the 1st fiber layer 1 produced beforehand, or to make it contact | adhere further.

  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 μm, more preferably 0.7 to 1.5 μm. When the second average fiber diameter is in the range, the collection performance of the fiber laminate can be improved, and the balance between the ventilation performance and the collection performance of the fiber laminate can be improved. If the second average fiber diameter is too small, it may be disadvantageous in terms of ventilation performance. An excessively large second average fiber diameter can be disadvantageous in terms of collection performance.

  The specific example of the fiber material which comprises a 2nd fiber assembly can be the same as that of a 1st fiber assembly. Among these, polyolefin resins, polyester resins, and polyamide resins are preferably used, and polyolefin resins are more preferably used. The fibers constituting the second fiber assembly may contain two or more kinds of thermoplastic resins. Among the polyolefin resins, polypropylene is preferably used. A polyolefin-based resin, particularly polypropylene, can be easily charged by a charging process described later, so that a fiber laminate having a higher filtration performance (collecting performance) by charging can be obtained more easily.

  When the fiber which comprises a 2nd fiber assembly contains a polypropylene, the said fiber may be comprised only with the polypropylene and may contain thermoplastic resins other than a polypropylene. In the latter case, the content of polypropylene is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more.

  The fibers constituting the second fiber assembly are conventional additives such as stabilizers (thermal stabilizers, ultraviolet absorbers, light stabilizers, antioxidants, etc.), antibacterial agents, deodorants, fragrances, and coloring agents. (Dyes and pigments), fillers, antistatic agents, flame retardants, plasticizers, lubricants and the like may be contained. Only 1 type may be used for an additive and it may use 2 or more types together. The additive may be supported on the fiber surface or may be contained in the fiber.

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

  In the case where the second fiber assembly is a melt blown nonwoven fiber assembly, the second average fiber diameter of the fibers constituting the second fiber assembly is the same as the fiber fiber collecting distance compared to the time of manufacturing the first fiber assembly. It can be controlled by adjusting the melt-blowing conditions such as increasing the length.

The basis weight W ₂ of the second fiber layer 2 (second fiber aggregate) is preferably smaller than that of the first fiber layer 1 (first fiber aggregate), and the ventilation performance and collection performance (contamination efficiency of foreign matter and From the viewpoint of (or collection capacity), it is preferably 0.5 to 30 g / m ² , more preferably 1 to 10 g / m ² or more. If the basis weight W ₂ is too small, it is difficult to obtain sufficient collection performance. If the basis weight W ₂ is too large, it is difficult to obtain good ventilation performance. The density (bulk density) D ₂ of the second fiber layer 2 in the fiber laminate is preferably 0.007 to 0.4 g / cm ³ , more preferably 0.015 to 0.3 g, from the viewpoint of air permeability. / Cm ³ . If the density D ₂ is too large, the ventilation performance may be reduced. If the density D ₂ is too small, it is difficult to obtain sufficient collection performance.

The thickness T ₂ of the second fiber layer 2 in the fiber laminate is preferably smaller than the thickness of the first fiber layer 1, and from the viewpoints of ventilation performance and collection performance (foreign material collection efficiency and / or collection capacity). Therefore, it is preferably 0.01 to 2 mm, more preferably 0.03 to 1 mm, and still more preferably 0.03 to 0.5 mm (for example, 0.1 mm or less). By setting the thickness T ₂ in the above range, the balance between the ventilation performance and the collection performance is improved.

(3) Fiber Laminate In the fiber laminate according to the present embodiment, not only the surface irregularities are provided, but also in order to provide a higher balance between the ventilation performance and the collection performance, the first fiber layer 1 and the first It is preferable to appropriately adjust at least one (preferably 2 or more, more preferably all) of the thickness ratio, the basis weight ratio, and the density (bulk density) ratio with the two fiber layers 2. The first and the thickness T ₁ of the fibrous layer 1 ratio T ₁ / T ₂ of the the thickness T ₂ of the second fibrous layer 2 is preferably 4 to 25, more preferably 6 to 20. Further, first and basis weight W ₁ of the fiber layer 1 ratio W ₁ / W ₂ of the basis weight W ₂ of the second fibrous layer 2 is preferably 3 to 20, more preferably from 4 to 15. The first density of the fiber layer 1 (bulk density) D ₁ and the ratio D ₁ / D ₂ of the second density of the fiber layer 2 (bulk density) D ₂ is preferably 0.2 to 0.99, more Preferably it is 0.3-0.8.

The thickness (total thickness) of the fiber laminate is preferably 0.4 to 7 mm, more preferably 0.5 to 5 mm, from the viewpoint of mechanical strength and handleability. From the viewpoint of collection performance, mechanical strength, and handleability, the basis weight of the fiber laminate (total basis weight) is 5.5 to 120 g / m ² , more preferably 10 to 60 g / m ² or more. . From the viewpoint of ventilation performance, the density of the fiber laminate (total density (bulk density)) is preferably 0.005 to 0.5 g / cm ³ , more preferably 0.01 to 0.2 g / cm ^{3. 3} , more preferably 0.1 g / cm ³ or less (for example, 0.01 to 0.1 g / cm ³ ).

From the viewpoint of the balance between the ventilation performance and the collection performance, the air permeability of the fiber laminate is an air permeability according to the Frazier method, preferably 80 to 1000 cc / cm ² / s, more preferably 100 cc / cm ² / s. s or more (for example, 100 to 800 cc / cm ² / s), 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 too high, it is difficult to obtain sufficient collection performance.

  The fiber laminate according to the present embodiment can be suitably used, for example, as a filter medium, and the collection efficiency measured in accordance with JIS T 8151 can be 85% or more, and further 90% or more. In the fiber laminate according to the present embodiment, the pressure loss measured according to JIS T 8151 can be 10 Pa or less, and further 5 Pa or less. Furthermore, the fiber laminate according to the present embodiment can have a QF value representing filter medium performance of 0.6 or more, further 0.8 or more, and even more 0.9 or more (for example, 1 or more). The definition of the QF value is as described in the example section.

  The fiber laminate is formed by spraying (preferably thinly) fibers forming the second fiber aggregate on the first main surface 11 of the first fiber aggregate (first fiber layer 1) prepared in advance by a melt blow method or the like. Can be manufactured by. According to this method, the fiber group sprayed on the first main surface 11 is solidified on the first main surface 11 in a state of being in close contact with the surface (or in a state in which many portions are in close contact). A fiber laminate having good bonding strength between the fiber layer 1 and the second fiber layer 2 can be obtained. This eliminates the need for a separate heat-sealing process such as hot embossing or a bonding process using an adhesive or the like, as described above. The bonding between the first fiber layer 1 and the second fiber layer 2 by heat fusion and the presence of an intervening layer such as an adhesive tends to lower the ventilation performance of the fiber laminate.

  In a method of forming (preferably thin) the second fiber aggregate (second fiber layer 2) on the first main surface 11 of the first fiber aggregate (first fiber layer 1) prepared in advance by the melt blow method or the like. In many cases, the shape of the first surface unevenness and the second surface unevenness of the second fiber layer 2 generally reflects the first surface unevenness. However, the shape of the 1st surface unevenness and the 2nd surface unevenness which the 2nd fiber layer 2 has does not need to reflect the 1st surface unevenness in all.

The fiber laminate according to the present invention may be one that has been subjected to electrification treatment (those imparted with chargeability) in order to further improve the collection performance. “Charging” refers to the state in which the fiber laminate is charged with electricity, preferably the surface charge density (the amount of charge measured using a Faraday cage [electrostatic charge meter] divided by the measurement area). Value) is 1.0 × 10 ⁻¹⁰ coulomb / cm ² or more, more preferably 1.5 × 10 ⁻¹⁰ coulomb / cm ² or more, and even more preferably 2.0 × 10 ⁻¹⁰ coulomb / cm ² or more. is there.

  Methods for imparting chargeability to the fiber laminate include a method of imparting electric charge by friction and contact, a method of irradiating active energy rays (for example, electron beam, ultraviolet ray, X-ray, etc.), gas discharge such as corona discharge, plasma, etc. And a suitable electret treatment such as a method using a high electric field, a hydrocharging method using a polar solvent such as water, and the like. Among them, the corona discharge method and the hydrocharging method are preferable because high chargeability can be obtained with a relatively low electric energy, and the hydrocharging method is more preferable because the chargeability can be imparted uniformly in the thickness direction.

In the hydrocharging method, for example, a polar solvent such as water or an organic solvent (preferably water from the viewpoint of productivity such as wastewater treatment) is sprayed on the fiber laminate or vibrated while spraying. Charge by. The pressure of the polar solvent colliding with the fiber laminate is preferably 0.1 to 5 MPa, more preferably 0.5 to 3 MPa, and the suction pressure from the lower part is preferably 500 to 5000 mmH ₂ O, more preferably 1000. ~3000mmH is a ₂ O. The treatment time for hydrocharging is preferably 0.01 to 5 seconds, more preferably 0.02 to 1 second. The charged fiber laminate after the hydrocharging method is preferably dried at a temperature of 40 to 100 ° C., preferably 50 to 80 ° C., for example.

  The apparatus and conditions used for the corona discharge method are not particularly limited. For example, a DC high voltage stabilized power source is used. For example, a linear distance between electrodes to which a voltage is applied: 5-70 mm (preferably 10-30 mm), applied voltage: − 50 to −10 kV and / or 10 to 50 kV (preferably −40 to −20 kV and / or 20 to 40 kV), temperature: normal temperature (20 ° C.) to 100 ° C. (preferably 30 to 80 ° C.), treatment time: 0. The reaction can be performed under conditions of 1 to 20 seconds (preferably 0.5 to 10 seconds).

  The fiber laminate according to the present embodiment can be suitably used as a filter medium. Specific examples of the filter medium include a human mask and an industrial filter medium (for example, an industrial air filter medium).

(Other embodiments)
With reference to FIGS. 2-5, the fiber laminated body which concerns on other embodiment of this invention is demonstrated. In the following, only points different from the fiber laminate shown in FIG. 1 will be described, and for the other points, the above description of the first embodiment is cited.

  In the fiber laminate shown in FIG. 2, the second main surface 12 of the first fiber layer 1 is configured with a relatively smooth surface (for example, a surface where the height of the convex portion is less than 0.1 mm). Has the same configuration as that of the fiber laminate shown in FIG.

  As shown in FIG. 3, the first surface irregularities of the first fiber layer 1 and the first surface irregularities of the second fiber layer 2 do not need to be in contact with each other, and the first fiber layer 1 and the second fibers You may have the part which both do not contact between the layers 2. For example, the first surface unevenness is formed on at least a part of the first main surface 21 of the second fiber layer 2, and the first surface unevenness and the first surface unevenness of the second fiber layer 2 are in contact with each other in this region. Can be mentioned.

  As described above, in the present invention, it is sufficient that at least one of the first main surface 11 of the first fiber layer 1 and the first main surface 21 of the second fiber layer 2 has the first surface unevenness, For example, as shown in FIG. 4, only the first fiber layer 1 has a first surface unevenness, and as shown in FIG. 5, only the second fiber layer 2 has a first surface unevenness. There may be.

  Also in the above embodiment, it is possible to combine high ventilation performance and high collection performance as in the first embodiment.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further more concretely, this invention is not limited by these examples. In addition, the measuring method of each physical-property value in a following example and a comparative example is as follows.

[1] Weight per unit (g / m ² )
According to JIS L 1913 "General nonwoven fabric test method", the basis weight of the entire fiber laminate and the basis weight of each of the first fiber layer and the second fiber layer were measured.

[2] Thickness (mm)
Using a table-top microscope (“Miniscope TM3030” manufactured by Hitachi High-Technologies Corporation), a 50 × photograph of the cross section of the fiber laminate was taken. In exposing the cross section, the fiber laminate was cut by pressing from the top to the bottom using a cutter (without performing an operation of returning the cutter from the bottom to the top after cutting the fiber laminate). Based on the obtained photograph, the thickness direction from the top of the convex portion of the second surface irregularities of the second fiber layer to the back surface of the fiber laminate (the second main surface of the first fiber layer, or the convex portion vertex when there are irregularities) The distance was measured at arbitrary 10 locations (however, 2 adjacent locations have a 1 mm spacing), and the average value of these was taken as the “thickness of the fiber laminate”. Moreover, based on the said photograph, it is a convex part when there exists an unevenness | corrugation from the convex part vertex of the 1st surface unevenness | corrugation (1st main surface) of a 1st fiber layer to the back surface (2nd main surface of a 1st fiber layer, an unevenness | corrugation). The thickness direction distance to the apex) was measured at any 10 locations (however, 2 adjacent locations have a 1 mm spacing), and the average value of these was defined as the “thickness of the first fiber layer”. . The “thickness of the first fiber layer” was subtracted from the “thickness of the fiber laminate” to obtain the “thickness of the second fiber layer”.

[3] Density (bulk density) (g / cm ³ )
By dividing the basis weight value obtained in [1] above by the thickness obtained in [2] above, the density of the entire fiber laminate and the density of each layer of the first fiber layer and the second fiber layer are obtained. It was.

[4] Height of convex part (mm)
Based on the photograph obtained in the above [2], from the surface of the first fiber layer excluding the convex portions of the first surface unevenness, when the back surface of the fiber laminate (the second main surface of the first fiber layer, if there are irregularities) The distance in the thickness direction to the vertex of the convex part) was measured at any five locations (however, two adjacent locations had a 1 mm interval), and the average value of these was determined. The average value was subtracted from the “thickness of the first fiber layer” obtained in [2] above to obtain “the height of the convex portions of the first surface irregularities” in the first fiber layer.

  Further, based on the photograph obtained in the above [2], the second surface irregularities of the second fiber layer from the surface of the second fiber layer excluding the convex portions of the first surface irregularities (surface irregularities on the first fiber layer side). The distance in the thickness direction to the top of the convex portion was measured at any five locations (however, two adjacent locations had a 1 mm interval), and the average value of these was determined. The average value was subtracted from the “thickness of the second fiber layer” obtained in [2] above to obtain “the height of the convex portions of the first surface irregularities” in the second fiber layer.

  The “height of the convex portions of the second surface irregularities” in the second fiber layer is measured as follows. Based on the photograph obtained in [2] above, the back surface of the fiber laminate from the surface of the second fiber layer excluding the convex portions of the second surface irregularities (if there are irregularities on the second main surface of the first fiber layer, irregularities) The distance in the thickness direction to the vertex of the convex part) is measured at any five locations (however, two adjacent locations have an interval of 1 mm), and an average value thereof is obtained. The average value is subtracted from the “thickness of the fiber laminate” obtained in [2] above to obtain the “height of the convex portions of the second surface irregularities” in the second fiber layer.

[5] Density of protrusions (pieces / cm ² )
Using a tabletop microscope ("Miniscope TM3030" manufactured by Hitachi High-Technologies Corporation), a 50 times photograph of a cross section parallel to the MD direction of the fiber laminate was taken. In exposing the cross section, the fiber laminate was cut by pressing from the top to the bottom using a cutter (without performing an operation of returning the cutter from the bottom to the top after cutting the fiber laminate). Any 10 locations in the thickness direction from the top of the convex portion of the first surface unevenness of the first fiber layer to the back surface of the fiber laminate (the second main surface of the first fiber layer, or the top of the convex portion when there is unevenness). (However, two adjacent places have a 1 mm interval.) A line perpendicular to the thickness direction was drawn at a position of 1/3 the interval (height) of these average values. The number of convex portions protruding from this line per 1 cm was defined as “the number of MD convex portions”. The same measurement was performed on the cross section parallel to the CD direction to obtain the “number of CD protrusions”. And "the density of the convex part of the 1st surface unevenness | corrugation" in a 1st fiber layer was calculated | required as a product of "MD convex part number" and "CD convex part number."

  Moreover, based on the photograph obtained above, from the convex part vertex of the 1st surface unevenness | corrugation which the 2nd fiber layer has to the 2nd main surface (surface except a convex part when there is an unevenness | corrugation) of a 2nd fiber layer. In the same manner as described above except that the distance in the thickness direction was measured at an arbitrary 10 locations (however, 2 adjacent locations have an interval of 1 mm). Part density ".

  The “density of convex portions of the second surface irregularities” in the second fiber layer is measured as follows. The distance in the thickness direction from the vertex of the convex portion of the second surface irregularity of the second fiber layer to the first main surface of the second fiber layer (the surface excluding the convex portion when there is irregularity) is any 10 locations (however, , Two adjacent points have an interval of 1 mm.), And a line perpendicular to the thickness direction is drawn at a position (height) of 1/3 of the average value. The number of protrusions protruding from this line per 1 cm is defined as “the number of MD protrusions”. The same measurement is performed on the cross section parallel to the CD direction to obtain the “number of CD protrusions”. And "the density of the convex part of the 2nd surface unevenness | corrugation" in a 2nd fiber layer is calculated | required as a product of "MD convex part number" and "CD convex part number."

[6] Average fiber diameter (μm)
Using a scanning electron microscope ("Miniscope TM3030" manufactured by Hitachi High-Technologies Corporation), a photograph was taken in which the surfaces of the first fiber layer and the second fiber layer were magnified 500 times. The diameters of 100 arbitrary fibers in the photograph were measured, and the average value of these was taken as the average fiber diameter. However, the fused fiber was excluded because the fiber diameter could not be measured clearly.

[7] Air permeability The air permeability (cc / cm ² / s) of the fiber laminate was measured according to the fragile method of JIS L 1913 “General nonwoven fabric test method”.

[8] Collection performance [8-1] Collection efficiency (%) and pressure loss (Pa)
In accordance with JIS T 8151, the fiber laminate was cut into a size of 11 cmφ, and this was set on a sample stage with a filtration part of 8.6 cmφ (filtration area: 58.1 cm ² ), the air volume was 20 L / min, and the surface speed was 5. The collection efficiency (%) and pressure loss (Pa) when NaCl particles (average particle size: 0.1 μm) were filtered at 7 cm / second were measured.

[8-2] QF value From the collection efficiency and pressure loss obtained in [8-1] above, the following formula:
QF value = -ln (1-collection efficiency (%) / 100) / pressure loss (Pa)
Based on the above, the QF value was calculated.

<Example 1>
Polypropylene [MFR (230 ° C., 21.18 N load) = 30 g / 10 min] is melt-extruded and discharged from a nozzle hole, and the fiber stream thinned by hot air is collected on a roll around which a conveyor net is wound. As a result, a first fiber aggregate (first fiber layer) having a basis weight of 20.0 g / m ² and having a first surface irregularity, which is a melt-blown nonwoven fiber aggregate, was obtained. Specific conditions of the melt blow method are as follows.

-Hole diameter: 0.4mm,
-Hole interval: 1.50 mm,
-Spinning temperature: 260 ° C
・ Single hole discharge rate: 0.3 g / min
・ Blowing hot air temperature: 260 ℃
・ Flow rate of ejected hot air: 13 Nm ³ / min (1 m),
・ Distance from nozzle to conveyor net: 32cm
Conveyor net type: Balance type (width pitch 5 mm × length pitch 5 mm × thickness 5 mm, 1 mmφ).

Next, using polypropylene [MFR (230 ° C., 21.18 N load) = 700 g / 10 min], the first surface which is a melt-blown nonwoven fiber aggregate on the first surface irregularities of the first fiber layer according to the following conditions A second fiber aggregate (second fiber layer) having a basis weight of 2.7 g / m ² having irregularities and second surface irregularities was formed to obtain a fiber laminate.

-Hole diameter: 0.3 mm,
-Hole interval: 0.75mm,
-Spinning temperature: 215 ° C
・ Single hole discharge rate: 0.036 g / min.
・ Blowing hot air temperature: 215 ° C
・ Flow rate of ejected hot air: 10 Nm ³ / min (1 m),
-Distance from nozzle to conveyor net: 11 cm.

  A tabletop micrograph of one section of the fiber laminate obtained in Example 1 is shown in FIG. It can be seen that the first fiber layer has first surface irregularities, and the second fiber layer has first surface irregularities and second surface irregularities. The convex part which comprises the 1st surface unevenness | corrugation was a brushed convex part (the same also in Examples 2-6).

  Next, the obtained fiber laminate was charged by a hydrocharging method. Specific conditions for the hydrocharging method are as follows.

・ Solvent: Water,
-Water pressure: 0.4 MPa,
・ Suction pressure: 2000 mmH ₂ O,
Processing time: 0.042 seconds (processing width 14 mm, speed 20 m / min).

<Example 2>
A first fiber assembly (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 basis weight was 15.0 g / m ² . Thereafter, a fiber laminate was produced in the same manner as in Example 1.

<Example 3>
Example 1 except that the type of conveyor net was changed to a balance type (width pitch 2.5 mm × length pitch 3 mm × thickness 4 mm, 0.8 mmφ) and the distance from the nozzle to the conveyor net was changed to 20 cm. In the same manner as above, a first fiber assembly (first fiber 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 basis weight of the first fiber layer was 10 g / m ² .

<Example 5>
A first fiber assembly (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 basis weight was 30.0 gm ² . Thereafter, a fiber laminate was produced in the same manner as in Example 3.

<Example 6>
In the formation of the second fiber layer, a fiber laminate was produced in the same manner as in Example 1 except that 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.

<Comparative Example 1>
In the formation of the first fiber layer, a fiber laminate was manufactured in the same manner as in Example 1 except that the type of the conveyor net was changed to a 200 mesh plain woven stainless steel wire mesh. In this fiber laminate, the first main surface (second fiber layer side surface) of the first fiber layer and the convex portions of the first main surface (first fiber layer side surface) of the second fiber layer have a height. Was 0.005 mm at the maximum, and the pressure loss was high and the QF value was high as compared with the fiber laminate of the example.

  About the fiber laminated body obtained by the Example and the comparative example, said [1]-[8] was measured. The results are shown in Table 1. The air permeability, collection efficiency, pressure loss, and QF value are values after the charging process.

  DESCRIPTION OF SYMBOLS 1 1st fiber layer, 2 2nd fiber layer, 11 1st main surface (2nd fiber layer side main surface) of 1st fiber layer, 12 2nd main surface (2nd fiber layer with 1st fiber layer side) The main surface on the opposite side), 21 The first main surface of the second fiber layer (main surface on the first fiber layer side), 22 The second main surface of the second fiber layer.

Claims (15)

A first fiber layer having a first main surface and composed of a first fiber assembly;
A fiber layer disposed on the first main surface, the second fiber layer comprising a second fiber assembly;
Including
At least one of the first main surface and the main surface on the first fiber layer side in the second fiber layer has first surface irregularities,
The fiber laminated body whose height of the convex part which comprises the said 1st surface unevenness | corrugation is 0.1 mm or more. The fiber laminate according to claim 1, wherein the density of the convex portions constituting the first surface irregularities is 3 pieces / cm ² or more.   The fiber laminate according to claim 1 or 2, wherein at least the first main surface has the first surface irregularities.   The main surface of the second fiber layer opposite to the first fiber layer has second surface irregularities, and the height of the convex portions constituting the second surface irregularities is 0.05 mm or more. The fiber laminated body of any one of 1-3. The fiber laminate according to claim 4, wherein the density of the convex portions constituting the second surface irregularities is 3 pieces / cm ² or more. The fiber laminated body of any one of Claims 1-5 whose bulk density is 0.1 g / cm < ³ > or less. Wherein the ratio T ₁ / T ₂ of the first and the thickness T ₁ of the fiber layer and the thickness T ₂ of the said second fibrous layer is 4 to 25, the fiber laminate according to any one of claims 1 to 6 .   The fiber laminate according to any one of claims 1 to 7, wherein the first fiber assembly and the second fiber assembly are non-woven fiber assemblies.   The fiber laminate according to claim 8, wherein the nonwoven fiber assembly includes a polyolefin resin fiber.   The fiber laminated body of any one of Claims 1-9 whose average fiber diameter of the fiber which comprises the said 2nd fiber assembly is 0.5-2 micrometers. The fiber laminated body of any one of Claims 1-10 whose air permeability is 100 cc / cm < ² > / s or more. The collection efficiency and pressure loss measured in accordance with JIS T 8151 are 85% or more and 10 Pa or less, respectively, and the following formula:
QF value = -ln (1-collection efficiency (%) / 100) / pressure loss (Pa)
The fiber laminated body according to any one of claims 1 to 11, wherein the QF value calculated according to the above is 0.6 or more.   The fiber laminate according to any one of claims 1 to 12, which has been charged.   The fiber laminate according to any one of claims 1 to 13, which is a filter medium.   The fiber laminate according to any one of claims 1 to 13, which is a cleaning tool.