TW201710065A - Fiber laminate - Google Patents

Abstract

Provided is a fiber laminate comprising: a first fiber layer that has a first main surface and is configured of a first fiber assembly; and a second fiber layer that is arranged on the first main surface and is configured of a second fiber assembly. The first main surface and/or the first fiber layer-side surface of the second fiber layer has a first surface asperity; and the height of a projected portion constituting the first surface asperity is 0.1 mm or more.

Description

Fiber laminate

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

As a filter medium typified by an air filter (air filter), a mask, etc., it is known to use a fiber layer such as a non-woven fabric or a laminate including a plurality of fiber layers.

For example, Japanese Patent No. 5205650 (Patent Document 1) discloses a laminate for an air filter having a fiber layer A of 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. The fiber layer B of the polyolefin-based fiber layer having a diameter of 5 to 60 μm and a thickness of 0.15 to 1.5 mm has a two-layer structure, and the density, the thickness ratio of the fiber layer A to the fiber layer B, and the air permeability are in a specific range. According to Patent Document 1, the laminate has high air permeability and collection efficiency.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent No. 5205650

An object of the present invention is to achieve an improvement in aeration performance and collection performance of a fibrous body which can be used for a filter medium or the like.

The present invention provides a fiber laminate as shown below.

[1] A fiber laminate comprising: a first fiber layer having a first main surface and comprising a first fiber assembly; and a second fiber comprising a second fiber assembly disposed on the first main surface In the layer, at least one of the first main surface and the main surface on the first fiber layer side of the second fiber layer has a first surface unevenness, and the height of the convex portion constituting the first surface unevenness 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], wherein at least the first main surface has the first surface unevenness.

[4] The fiber laminate according to any one of [1], wherein the main surface of the second fiber layer opposite to the first fiber layer has a second surface unevenness, and the second surface unevenness is formed. The height of the convex portion is 0.05 mm or more.

[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~ 25.

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

[9] The fiber laminate according to [8], wherein the nonwoven fabric assembly 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 assembly 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 100 cc/cm ² /s or more.

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

[13] The fiber laminate according to any one of [1] to [12] which is subjected to a 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 sweeping tool.

According to the present invention, it is possible to provide a fibrous body excellent in aeration performance and collection performance. The fibrous body (fiber laminate) of the present invention is suitable for a filter medium such as an air filter or a mask.

1‧‧‧1st fibrous layer

2‧‧‧2nd fibrous layer

11‧‧‧ The first main surface of the first fiber layer (the main surface on the second fiber layer side)

12‧‧‧2nd main surface of the first fibrous layer (main surface opposite to the second fibrous layer)

21‧‧‧ The first main surface of the second fiber layer (the main surface on the first fiber layer side)

22‧‧‧2nd main surface of the 2nd fiber layer

Fig. 1 is a schematic cross-sectional view showing an example of a fiber laminate according to a first embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view showing an example of a fiber laminate according to a second embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view showing an example of a fiber laminate according to a third embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view showing an example of a fiber laminate according to a fourth embodiment of the present invention.

Fig. 5 is a schematic cross-sectional view showing an example of a fiber laminate according to a fifth embodiment of the present invention.

Figure 6 is a photomicrograph of a cross-sectional view of one of the fiber laminates of Example 1.

The present invention relates to a fiber laminate comprising a first fiber layer having a first main surface and comprising a first fiber assembly, and a second fiber layer disposed on the first main surface and composed of a second fiber assembly. In the fiber layer, at least one of the first main surface (inner main surface) of the first fiber and the first main surface (inner main surface) on the first fiber layer side of the second fiber layer has surface irregularities. The present invention will be described in detail below with reference to the embodiments.

(First embodiment)

Fig. 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 assembly, and a second fiber layer 2 which is disposed on the first main surface 11 and is composed of a second fiber assembly. The first fiber layer 1 has a first main surface (inner main surface) 11 on the main surface on the second fiber layer 2 side and a second main surface on the opposite side to the second fiber layer 2 (the outer main surface) Face) 12. The second fiber layer 2 has a first main surface (inner main surface) 21 on the main surface on the first fiber layer 1 side and a second main surface on the opposite side to the first fiber layer 1 (outer main surface) Face) 22.

The first main surface 11 of the first fiber layer 1 is formed by surface irregularities, and the second fiber layer 2 is laminated thereon. The second fiber layer 2 is in contact with the first main surface 11 of the first fiber layer 1 over the entire or substantially the entire surface. Therefore, the first main surface 21 of the second fiber layer 2 also has surface irregularities of the transfer mold (or about the transfer mold) 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 formed of irregularities. In the present specification, the first main surface of the first fiber layer 1 11 and/or the surface unevenness which the first main surface 21 of the second fiber layer 2 can have is also collectively referred to as "first surface unevenness".

The second fiber layer 2 of the fiber laminate shown in Fig. 1 also has surface irregularities on the second main surface 22 thereof. In the present specification, the surface unevenness which the second main surface (outer main surface) 22 of the second fiber layer 2 can have is also referred to as "second surface unevenness". The first fiber layer 1 of the fiber laminate shown in Fig. 1 also has surface irregularities on the second main surface 12 thereof. In the present specification, the surface unevenness which the second main surface (outer main surface) 12 of the first fiber layer 1 can have is also referred to as "third surface unevenness".

As exemplified by the fiber laminate shown in Fig. 1, the fiber laminate of the present embodiment (the same applies to other embodiments to be described later) has the feature that the first main surface 11 and the second fiber of the first fiber layer 1 are the first main surface 11 and the second fiber. At least one of the first main faces 21 of the layer 2 has a first surface unevenness. According to the fiber laminate of the present embodiment, both the high aeration performance and the high collection performance can be achieved. The fiber laminate of the present embodiment can be preferably used as a filter material such as an air filter or a mask. When the fiber laminate of the present embodiment is applied to a mask for a person, for example, it has high ventilation performance (low pressure loss), so that it is difficult to feel sultry long-term wearability (the property of being unpleasant to feel sultry when worn for a long time) is excellent. And because of its high trapping performance, it can effectively capture foreign matter in viruses or gases such as dust, dust, dust mites, pollen, and yellow sand. Moreover, when applied to, for example, an industrial air filter, since it has high ventilation performance, the processing speed of filtration (foreign matter removal) can be improved, and since it has high trapping performance, high collection efficiency and/or high trapping can be achieved. The capacity captures foreign matter in the air such as dust and dust.

Further, the fiber laminate of the present embodiment (in the same manner as in the other embodiments described later) can be used for removing the adhesion to the human or the bedding by using the second surface unevenness of the second main surface 22 of the second fiber layer 2. A cleaning tool represented by a rag such as the above-mentioned foreign matter of the article.

Further, in the present invention, the main surface having the first surface unevenness may have at least a part of the first surface unevenness, and it is not necessary to form all of 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 all (or substantially all) of the main surfaces having the first surface unevenness are formed by the first surface unevenness. The same applies to the second and third surface irregularities.

Hereinafter, the fiber laminate of the present embodiment (first embodiment) will be described in further detail.

(1) The first fibrous layer

The first fiber layer 1 is a layer composed of a first fiber assembly, and the first main surface (inner main surface) 11 (main surface on the second fiber layer 2 side) has a first surface unevenness, and the second main surface (outer main surface) The surface 12 has a third surface unevenness. The first main surface 11 is preferably formed by the first surface unevenness, and the second main surface 12 is preferably formed by the third surface unevenness. The first surface unevenness of the first main surface 11 forms a surface of the interface with the second fiber layer 2 (the first main surface 21 of the second fiber layer also has the first surface unevenness), and the interface of the two fiber layers is The uneven structure can improve the collection performance and aeration performance of the fiber laminate. Further, it has the third surface unevenness, and is advantageous in terms of further improvement in collection performance and ventilation performance. First main surface (inside main surface) 11 and second main The convex portions of the surface (outer main surface) 12 may exist 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 raised shape, or the like.

The height of the convex portion constituting the first surface unevenness of the first main surface (inner main surface) 11 is 0.1 mm or more, preferably 0.2 mm or more, more preferably 0.3, from the viewpoint of improving the collection performance of the fiber laminate. Above mm (for example, 0.4mm or more). The height of the convex portion is usually 5 mm or less, more preferably 3 mm or less (for example, 2 mm or less). When the convex portion is too low and the height is less than 0.1 mm, when the first main surface 11 is relatively smooth, the collection performance is not improved or insufficient. When the convex portion is too high, the mechanical strength of the fiber laminate becomes unfavorable. Further, from the viewpoint of improving the collection performance of the fiber laminate, the density of the projections in the first surface unevenness is preferably 3 pieces/cm ² or more, more preferably 10 pieces/cm ² or more. The density of the convex portion is usually 50 pieces/cm ² or less, and typically 30 pieces/cm ² or less. When the density of the convex portion is too large, the air permeability of the fiber laminate may be adversely affected. The height and density of the projections were determined using a table microscope according to the method described in the examples. The height and density of the convex portions constituting the third surface unevenness may be the same as the height and density of the convex portions constituting the first surface unevenness of the first fibrous layer 1.

The first fiber assembly constituting the first fiber layer 1 may be formed of a woven fabric, but is preferably a nonwoven fabric aggregate. Among them, the first fiber assembly is more preferably a meltblown nonwoven fiber assembly. By using the spray-melting method, it is possible to easily and inexpensively produce a nonwoven fabric aggregate having a small bulk density and excellent aeration performance and having a first surface unevenness and a third surface unevenness. In the melt blow method, a general melt blow spinning device can be used.

When the melt blow method is used, the first fiber layer 1 is produced as a fiber web obtained by collecting fibers which are ejected from the nozzles on the uneven surface of the collector. In other words, the concave portion (or the penetration portion) of the collecting surface intrudes into the fiber and solidifies, thereby providing unevenness to one main surface or both main surfaces of the first fiber assembly. The collecting group may be a metal collecting group in which a plurality of (or a plurality of) convex portions or concave portions are provided, a metal mesh having a mesh, a card clothing, or the like. Among them, a mesh having a three-dimensional structure generally called a conveyor net is preferably used, whereby a nonwoven fabric aggregate having a first surface unevenness and a third surface unevenness can be more easily produced.

The convex portion constituting the first surface unevenness may be a raised portion. The raised protrusion is preferably one having a straightness. When a net such as a conveying net is used as the collecting group, the convex portion is likely to be a raised protrusion. The fiber laminate which will be described later can be produced by blowing a fiber of the second fiber assembly by a melt blow method or the like on the first main surface 11 of the first fiber assembly (first fiber layer 1) which is prepared in advance. However, if the convex portion constituting the first surface unevenness is a raised portion, the bonding force between the first fiber layer 1 and the second fiber layer 2 is increased, whereby the durability of the fiber laminate can be improved.

The average fiber diameter (first average fiber diameter) of the fibers constituting the first fiber assembly is preferably from 5 to 50 μm, more preferably from 7 to 25 μm. When the first average fiber diameter is in the range, it is possible to impart rigidity to the first fiber assembly (first fiber layer 1) while maintaining the first surface unevenness and maintaining the third surface uneven shape after the fiber laminate is formed. . And if the first average fiber diameter is in the above range, the aeration property of the fiber laminate is improved. The balance with the capture performance is also advantageous. When the first average fiber diameter is too small, the ventilation performance is liable to lower. When the first average fiber diameter is too large, the collection performance is liable to lower.

The fibers constituting the first fiber assembly usually contain fibers made of a thermoplastic resin. Specific examples of the thermoplastic resin include a polyolefin resin (e.g., low density, medium density or high density polyethylene, polypropylene poly C _2-4 olefin resin, etc.); styrene resin (heat resistant polystyrene, etc.); ester resin (e.g., polyethylene terephthalate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polyethylene terephthalate C _2-4 stretch Alkyl aromatic acid ester resin, etc.; polyammonium-based resin (such as polyamine 6, polyamine 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612 aliphatic poly Amine-based resin, semi-aromatic polyamine-based resin, such as poly(phenylene isophthalamide), polyhexamethylene terephthalamide, poly-p-phenylene terephthalamide A phthalic acid resin or the like; a polycarbonate resin (such as a bisphenol A polycarbonate); a polyurethane resin; a cellulose resin (such as a 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 fiber constituting the first fiber assembly may also contain two or more kinds of thermoplastic resins.

A preferred user of the polyolefin resin is polypropylene. In the case of a polyolefin-based resin, in particular, a polypropylene, since it can be easily charged by a charging treatment to be described later, it is easier to obtain a fiber laminate having higher filtration performance (capturing performance) by charging. When the fiber constituting the first fiber assembly contains polypropylene, the fiber may be composed only of polypropylene, and may contain a thermoplastic resin other than polypropylene. In the latter case, the polypropylene content is better 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more.

The fibers constituting the first fiber assembly may also contain conventional additives such as stabilizers (heat stabilizers, ultraviolet absorbers, photosensitizers, antioxidants, etc.), antibacterial agents, deodorants, perfumes, colorants (dyes). Pigments, etc.), fillers, antistatic agents, flame retardants, plasticizers, lubricants, etc. The additive may be used alone or in combination of two or more. The additive may be supported on the surface of the fiber or may be 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, more preferably 200 g/10 min or less. When the MFR exceeds 400 g/10 minutes, the fiber flow ejected from the nozzle is easily refined, and it is difficult to maintain a high average fiber diameter. The MFR of the polypropylene is preferably 10 g/min or more from the viewpoint of resin sprayability from the nozzle.

The intrinsic viscosity of the polyester resin is preferably 0.7 or more, more preferably 0.8 to 1.5. Further, the relative viscosity of the polyamide resin is preferably 2 or more, preferably 2.2 to 3.0, and the use of such a resin makes it easy to manufacture a melt-blown nonwoven fabric aggregate having a high average fiber diameter.

When the first fiber assembly is a melt-blown nonwoven fiber assembly, the first fiber assembly which is rigid and which maintains the first surface unevenness and maintains the shape of the third surface unevenness after forming the fiber laminate is formed. Preferably, the fibers of the meltblown fiber stream are in a coarse state prior to refining, and the fibers are allowed to reach the capture surface prior to curing of the fibers. After the fiber stream is solidified, it is necessary to cool the trapping surface because it is necessary to peel off the trapping surface with irregularities. The situation.

Further, in order to form the first fiber assembly exhibiting the above-mentioned rigidity, it is preferred to lengthen the fiber diameter by shortening the collection distance of the fiber flow or to increase the resin viscosity, and to elongate the time before curing. The trapping distance is, for example, 5 to 100 cm, more preferably 10 to 60 cm. The resin viscosity varies depending on the resin used and the melting temperature, but it can be, for example, 10 to 100 Pa. s, preferably 20~50Pa. s.

The basis weight W _{1 of the} first fiber layer 1 (first fiber assembly) is preferably from 5 to 100 g/m from the viewpoints of aeration performance and collection performance (collection efficiency of foreign matter and/or collection capacity). ² , more preferably 10~50g/m ² or more. If the weight per unit area W _{1 is} too small, it is difficult to obtain sufficient filtration performance. When the weight per unit area W _{1 is} too large, it is difficult to obtain good ventilation performance. The first fiber layer laminate of fiber density (bulk density) of 1 D _1, from the viewpoint of performance of ventilation, preferably 0.005 ~ 0.5g / cm ^3, more preferably 0.01 ~ 0.2g / cm ^3. When the density D _{1 is} too large, there is a problem that the ventilation performance is lowered. When the density D _{1 is} too small, it is difficult to obtain sufficient filtration performance, and there is a fear that the mechanical strength of the fiber laminate is lowered.

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

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

(2) second fiber layer

The second fiber layer 2 is a layer composed of a second fiber assembly, and the first main surface (inner main surface) 21 (the main surface on the first fiber layer 1 side) may have a first surface unevenness, and the second main surface (outer side) The main surface 22 may have a second surface unevenness. The first main surface 21 is preferably formed by the first surface unevenness, and the second main surface 22 is preferably formed by the second surface unevenness. In view of improving the collection performance and the aeration performance of the fiber laminate, as in the present embodiment, it is preferred that at least the first main surface 11 of the first fiber layer 1 has the first surface unevenness, and the first fiber layer 1 is preferably the first. Both the main surface 11 and the first main surface 21 of the second fiber layer 2 have the first surface unevenness. Further, when the second main surface 22 of the second fiber layer 2 has the second surface unevenness, it is advantageous in improving the collection performance and the ventilation 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 be present in a regular manner or may be randomly present. 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 raised shape, or the like.

The height and density of the convex portion of the first main surface (inner main surface) 21 of the second fiber layer 2 are referred to as the first fiber layer 1 The above description of the convex portion of the first main surface (inner main surface) 11 is provided.

The height of the convex portion constituting the second surface unevenness of the second main surface 22 is preferably 0.05 mm or more, more preferably 0.1 mm or more, and more preferably 0.2 mm or more (for example, from the viewpoint of improving the collecting performance of the fiber laminate). 0.3mm or more). The height of the convex portion is usually 5 mm or less, more preferably 3 mm or less (for example, 2 mm or less). When the convex portion is too low and the height is less than 0.05 mm, when the second main surface 22 is smooth, the collection performance is not improved or insufficient. When the convex portion is too high, the mechanical strength of the fiber laminate becomes unfavorable. Further, from the viewpoint of improving the collection performance of the fiber laminate, the density of the projections in the second surface unevenness is preferably 3 pieces/cm ² or more, more preferably 10 pieces/cm ² or more. The density of the convex portion is usually 50 pieces/cm ² or less, and typically 30 pieces/cm ² or less. When the density of the convex portion is too large, the air permeability of the fiber laminate may be adversely affected.

The second fiber assembly constituting the second fiber layer 2 may be formed of a woven fabric, but is preferably a nonwoven fabric aggregate. Among them, the second fiber assembly is more preferably a melt-blown nonwoven fiber assembly. By using the spray-melting method, it is possible to easily laminate the previously-formed first fiber layer 1 with a desired average fiber diameter without performing another heat-melting step such as hot embossing or a subsequent step using an adhesive or the like. The second fiber aggregate (second fiber layer 2) made of fibers is further adhered.

The average fiber diameter (second average fiber diameter) of the fibers constituting the second fiber assembly is preferably smaller than the average fiber diameter (first average fiber diameter) of the fibers constituting the first fiber assembly. Specifically, the second average fiber diameter is preferably from 0.5 to 2 μm, more preferably from 0.7 to 1.5 μm. By making the second When the average fiber diameter is within this range, the collection performance of the fiber laminate can be improved, and the balance between the aeration property and the collection performance of the fiber laminate can be improved. When the second average fiber diameter is too small, it may be disadvantageous in terms of aeration performance. When the second average fiber diameter is too large, it may be disadvantageous in terms of the collection performance.

Specific examples of the fiber material constituting the second fiber assembly may be the same as those of the first fiber assembly. Among them, a polyolefin resin, a polyester resin, and a polyamide resin are preferably used, and a polyolefin resin is more preferably used. The fiber of the second fiber assembly may contain two or more kinds of thermoplastic resins. A preferred user of the polyolefin resin is a polyolefin. In the case of a polyolefin-based resin, in particular, a polypropylene, since it can be easily charged by a charging treatment to be described later, it is easier to obtain a fiber laminate having higher filtration performance (capturing performance) by charging.

When the fiber constituting the second fiber assembly contains polypropylene, the fiber may be composed only of polypropylene, and may contain a thermoplastic resin other than polypropylene. In the latter case, the polypropylene content is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more.

The fibers constituting the second fiber assembly may also contain conventional additives such as stabilizers (heat stabilizers, ultraviolet absorbers, photosensitizers, antioxidants, etc.), antibacterial agents, deodorants, perfumes, colorants (dyes). Pigments, etc.), fillers, antistatic agents, flame retardants, plasticizers, lubricants, etc. The additive may be used alone or in combination of two or more. The additive may be supported on the surface of the fiber or may be 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, more preferably 700 g/10 min. on. When the MFR is less than 500 g/10 minutes, the fiber flow ejected from the nozzle is not easily refined, and it is difficult to maintain a low average fiber diameter. The MFR of the polypropylene is preferably 2000 g/min or less from the viewpoint of the resin ejection property from the nozzle.

When the second fiber assembly is a melt-blown nonwoven fiber assembly, the second average fiber diameter of the fibers constituting the second fiber assembly can be adjusted by adjusting the fiber flow distance longer than when the first fiber assembly is produced. Controlled by melt-blown conditions.

The second fiber layer 2 (second fiber aggregate) has a basis weight W ₂ , preferably smaller than the first fiber layer 1 (first fiber aggregate), and is based on aeration performance and collection performance (the collection efficiency of foreign matter and The viewpoint of the collection capacity is preferably from 0.5 to 30 g/m ² , more preferably from 1 to 10 g/m ² or more. If the weight per unit area W _{2 is} too small, it is difficult to obtain sufficient filtration performance. When the weight per unit area W _{2 is} too large, it is difficult to obtain good ventilation performance. The second fiber layer 2 of the laminate of the fibrous layer density (bulk density) D _2, from the viewpoint of performance of ventilation, preferably 0.007 ~ 0.4g / cm ^3, more preferably 0.015 ~ 0.3g / cm ^3. When the density D _{2 is} too large, there is a problem that the ventilation performance is lowered. When the density D _{2 is} too small, it is difficult to obtain sufficient trapping performance.

The thickness T ₂ of the second fiber layer 2 of the fiber laminate is preferably smaller than the thickness of the first fiber layer 1, and is preferably based on the aeration property and the collection performance (the collection efficiency and/or the collection capacity of the foreign matter). It is 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 within this range, the balance between the aeration performance and the trapping performance is good.

(3) Fiber laminate

In the fiber laminate of the present embodiment, not only the surface unevenness is provided, but also the thickness ratio and the unit area ratio of the first fiber layer 1 and the second fiber layer 2 are preferably appropriately adjusted in order to provide a higher balance between the aeration performance and the collection performance. At least one of the ratios of density (loose density) (better than 2, better all). The ratio T ₁ /T ₂ of the thickness T ₁ of the first fiber layer 1 to the thickness T ₂ of the second fiber layer 2 is preferably 4 to 25, more preferably 6 to 20. Further, the ratio W ₁ /W ₂ of the unit area weight W ₁ of the first fiber layer 1 to the unit area weight W ₂ of the second fiber layer 2 is preferably 3 to 20, more preferably 4 to 15. The ratio D ₁ /D ₂ of the density (loose density) D ₁ of the first fiber layer 1 to the density (looseness) D ₂ of the second fiber layer 2 is preferably from 0.2 to 0.99, more preferably from 0.3 to 0.8.

The thickness (total thickness) of the fiber laminate is preferably from 0.4 to 7 mm, more preferably from 0.5 to 5 mm, from the viewpoint of mechanical strength and handleability. The basis weight of the fiber laminate (weight per unit area) is 5.5 to 120 g/m ² , more preferably 10 to 60 g/m ² or more, from the viewpoints of the collection performance, the mechanical strength, and the handleability. The density of the fiber laminate (density (bulk density) of the entire fiber) is preferably from 0.005 to 0.5 g/cm ³ , more preferably from 0.01 to 0.2 g/cm ³ , still more preferably from 0.1 g/s. Below cm ³ (for example, 0.01 to 0.1 g/cm ³ ).

The air permeability of the fiber laminate is preferably 80 to 1000 cc/cm ² /s, more preferably 100 cc, based on the balance between the venting performance and the trapping performance, and the air permeability of the fiber laminate. /cm ² /s or more (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). When the air permeability of the fiber laminate is too high, it is difficult to obtain sufficient trapping performance.

The fiber laminate of the present embodiment can be preferably used as, for example, a filter medium, and the collection efficiency measured according to JIS T8151 can be 85% or more, and further 90% or more. Further, the pressure loss measured by the fiber laminate of the present embodiment in accordance with JIS T8151 may be 10 Pa or less, and may be 5 Pa or less. Further, the fiber laminate of the present embodiment has a QF value of the filter material performance of 0.6 or more, further 0.8 or more, and further 0.9 or more (for example, 1 or more). The definition of the QF value can be as described in the examples.

The fiber laminate can be formed by the melt blowing method or the like (preferably thin) by forming a second fiber assembly by the first main surface 11 of the first fiber assembly (first fiber layer 1) prepared in advance. Made of fiber. According to this method, the fiber group blown on the first main surface 11 is on the first main surface 11 and is solidified in a state in which the surface is adhered (or a state in which a part of the surface is adhered), so that the first fiber layer 1 can be obtained. A fiber laminate having good adhesion strength to the second fiber layer 2. Thereby, as described above, an additional thermal fusion step such as hot embossing or a subsequent step using an adhesive or the like is not required. When the first fiber layer 1 and the second fiber layer 2 are joined by heat fusion or a barrier layer such as an adhesive is present, the aeration property of the fiber laminate is liable to lower.

The second fiber assembly (second fiber layer 2) is formed on the first main surface 11 of the first fiber assembly (first fiber layer 1) prepared in advance by a melt blow method or the like (preferably thin). In the method, the shape of the first surface unevenness and the second surface unevenness of the second fibrous layer 2 are mostly It is the person who is approximately the first surface bump. However, it is not necessary for the shape of the first surface unevenness and the second surface unevenness of the second fiber layer 2 to reflect the first surface unevenness.

The fiber laminate of the present invention may be subjected to a charging treatment (to impart chargeability) in order to further improve the collection performance. The term "charged" means a state in which the fiber laminate is charged, and it is preferable that the surface charge density (the value obtained by dividing the amount of charge measured by the Faraday cage "electrostatic charge meter" by the measured area) is 1.0 × 10 ^-10 coulomb/cm ² or more, more preferably 1.5 × 10 ^-10 coulomb/cm ² or more, still more preferably 2.0 × 10 ^-10 coulomb/cm ² or more.

The method of imparting chargeability to the fiber laminate is exemplified by a method of imparting electric charge by friction or contact, a method of irradiating an active energy ray (for example, an electron beam, an ultraviolet ray, an X-ray, etc.), and a gas such as corona discharge or plasma. The method of discharging is an electret treatment such as a liquid charging method using a polar solvent such as water by an electric field method. Among them, the corona discharge method and the liquid charging method are preferable because they can obtain high chargeability at a low electric quantity, and the liquid charging method is preferable because it can impart uniform chargeability in the thickness direction.

In the liquid charging method, the fiber laminate is sprayed by a polar solvent such as water or an organic solvent (preferably from the viewpoint of productivity such as drainage treatment), and is vibrated while being sprayed to be charged. The pressure of the polar solvent which collides with the fiber laminate is preferably from 0.1 to 5 MPa, more preferably from 0.5 to 3 MPa, and the suction pressure from the lower portion is preferably from 500 to 5,000 mmH ₂ O, more preferably from 1,000 to 3,000 mmH ₂ O. The treatment time of the liquid charging is preferably 0.01 to 5 seconds, more preferably 0.02 to 1 second. The fiber laminate charged after the liquid charging method is preferably dried at a temperature of, for example, 40 to 100 ° C, more preferably 50 to 80 ° C.

The apparatus and conditions used in the corona discharge method are not particularly limited, and for example, a DC high voltage stabilized power source can be used, for example, a linear distance between electrodes for applying a voltage: 5 to 70 mm (preferably 10 to 30 mm), and an applied voltage: - 50~-10kV and / or 10~50kV (better -40~-20kV and / or 20~40kV), temperature: normal temperature (20 °C) ~ 100 °C (good 30~80 °C), processing time: 0.1~ The condition is 20 seconds (preferably 0.5 to 10 seconds).

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

(Other embodiments)

A fiber laminate according to another embodiment of the present invention will be described with reference to Figs. 2 to 5 . Further, the description will be made on the difference from the fiber laminate shown in Fig. 1, and the above description of the first embodiment will be referred to in other respects.

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

As shown in FIG. 3, the first surface unevenness of the first fiber layer 1 The first surface unevenness of the second fiber layer 2 is required to be in full contact with each other, and the first fiber layer 1 and the second fiber layer 2 may have portions that are not in contact with each other. For example, at least a part of the first main surface 21 of the second fiber layer 2 is formed with a first surface unevenness, and in this region, the first surface unevenness and the first surface of the second fiber layer 2 are in contact with each other.

In the present invention, as long as 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, it may be as shown in the drawing. As shown in FIG. 4, only the first fiber layer 1 has the first surface unevenness, or as shown in FIG. 5, only the second fiber layer 2 has the first surface unevenness.

In the above embodiment, as in the first embodiment, both the high ventilation performance and the high collection performance can be achieved.

[Examples]

Hereinafter, the present invention will be specifically described by showing examples, but the present invention is not limited by the examples. Further, the methods for measuring the physical property values in the following examples and comparative examples are as follows.

[1] Unit weight (g/m ² )

The basis weight of the entire fiber laminate and the weight per unit area of each of the first fiber layer and the second fiber layer were measured in accordance with JIS L 1913 "General Nonwoven Test Method".

[2] Thickness (mm)

A 50-fold photograph of the cross section of the fiber laminate was taken using a table microscope ("Miniscope TM3030" manufactured by Hitachi High-Technologies Corporation). When the cross section is exposed, the fiber laminate is cut by pressing the cutter from the top to the bottom (the operation of cutting the fiber laminate without cutting the cutter from the bottom to the top). Based on the obtained photograph, the apex of the convex portion from the second surface unevenness of the second fiber layer to the back surface of the fiber laminate (the second main surface of the first fiber layer) was measured for any ten portions (the interval between the adjacent two portions was 1 mm) The distance in the thickness direction of the apex of the convex portion when there is unevenness, and the average value of these is referred to as "the thickness of the fiber laminate". Moreover, based on the above-mentioned photograph, the apex of the convex portion from the first surface unevenness (first main surface) of the first fiber layer to the back surface of the fiber laminate was measured for any ten portions (the interval between the adjacent two portions was 1 mm). The distance between the first main surface of the fiber layer and the apex of the convex portion in the case of irregularities is the thickness of the first fiber layer. The "thickness of the first fiber layer" is subtracted from the "thickness of the fiber laminate" and the thickness of the second fiber layer is set.

[3] Density (loose density) (g/cm ³ )

By dividing the weight per unit area obtained in the above [1] by the thickness obtained in the above [2], the density of the entire fiber laminate and the density of each layer of the first fiber layer and the second fiber layer were determined.

[4] convex height (mm)

Based on the photograph obtained in the above [2], the convexity of the first surface was measured for any five parts (but the interval between the adjacent two parts was 1 mm). The distance between the surface of the first fiber layer except the portion to the back surface of the fiber laminate (the second main surface of the first fiber layer, the apex of the convex portion when there is unevenness) is obtained, and the average value of these is obtained. The average value of the "first fiber layer thickness" obtained in the above [2] is subtracted from the average value, and the "first surface unevenness convex portion height" of the first fiber layer is used.

In addition, based on the photograph obtained in the above [2], the first surface irregularities (surface irregularities on the first fiber layer side) are excluded from the convex portions of the first surface irregularities (the first two fiber portions have an interval of 1 mm). The distance between the surface of the fiber layer and the apex of the convex portion of the second surface unevenness of the second fiber layer in the thickness direction is obtained as an average value. The average value of the "second fiber layer thickness" obtained in the above [2] is subtracted from the average value, and the "first surface unevenness convex portion height" of the second fiber layer is used.

Moreover, the "height of the convex portion of the second surface unevenness" of the second fiber layer was measured as follows. Based on the photograph obtained in the above [2], the surface of the second fiber layer excluding the convex portion of the second surface unevenness was measured to the back surface of the fiber laminate for any five portions (the interval between the adjacent two portions was 1 mm) (1st) The distance between the second main surface of the fiber layer and the apex of the convex portion in the case of irregularities is obtained in the thickness direction, and the average value of these is obtained. The "fiber laminate thickness" obtained in the above [2] is subtracted from the average value to determine the "second surface unevenness convex portion height" of the second fiber layer.

[5] convex density (units/cm ² )

Using a table microscope ("Miniscope TM3030" manufactured by Hitachi High-Technologies Co., Ltd.), the cross section of the fiber laminate parallel to the MD direction was taken. 50 times the photo. When the cross section is exposed, the fiber laminate is cut by pressing the cutter from the top to the bottom (the operation of cutting the fiber laminate without cutting the cutter from the bottom to the top). The apex of the convex portion from the first surface unevenness of the first fiber layer to the back surface of the fiber laminate is measured for any of the ten portions (the distance between the adjacent two portions is 1 mm) (the second main surface of the first fiber layer is uneven) The distance in the thickness direction of the apex of the convex portion is a line perpendicular to the thickness direction at a position (height) of 1/3 of the average value of the convex portions. The number of convex portions per 1 cm which jumped out from the line is set to "MD convex number". The same operation is performed for the cross section parallel to the CD direction, and the "number of CD convex portions" is obtained. The "first convex portion density of the first surface unevenness" of the first fiber layer is obtained by multiplying the "number of MD convex portions" and the "number of CD convex portions".

Further, in addition to the photograph obtained as described above, the apex of the convex portion from the first surface unevenness of the second fiber layer to the second of the second fiber layer was measured for any of the ten portions (the interval between the adjacent two portions was 1 mm). The "first surface unevenness convex portion density" of the second fiber layer was determined in the same manner as described above except for the distance in the thickness direction of the main surface (the surface excluding the convex portion when the unevenness was formed).

Moreover, the "density of the convex portion of the second surface unevenness" of the second fiber layer was measured as follows. The apex of the convex portion from the second surface unevenness of the second fiber layer to the first main surface of the second fiber layer is measured for any of the ten portions (the interval between the adjacent two portions is 1 mm). In the thickness direction of the excluded surface, a line perpendicular to the thickness direction is drawn at a position (height) of one-third of the average value. Will The number of convex portions per 1 cm of the line jump is set to "MD convex number". The same operation is performed for the cross section parallel to the CD direction, and the "number of CD convex portions" is obtained. Next, the "density of the convex portion of the second surface unevenness" of the second fiber layer is obtained by multiplying the "number of MD convex portions" and the "number of CD convex portions".

[6] Average fiber diameter (μm)

A 500-fold enlarged photograph of the surface of the first fiber layer and the second fiber layer was taken using a table microscope ("Miniscope TM3030" manufactured by Hitachi High-Technologies Corporation). The diameter of any 100 fibers in the photograph was measured, and the average of these was defined as the average fiber diameter. However, since the fused fiber cannot be clearly measured, the fiber diameter is outside the target.

[7] ventilation performance

The air permeability (cc/cm ² /s) of the fiber laminate was measured in accordance with the Frazier method of JIS L 1913 "General Nonwoven Test Method".

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

Cut the fiber laminate 11cm according to JIS T 8151 The size is fixed to the filter section 8.6cm The sample table (filtration area: 58.1 cm ² ) was used to measure the collection efficiency (%) and pressure loss (Pa) when filtering NaCl particles (average particle diameter: 0.1 μm) at an air volume of 20 L/min and a surface speed of 5.7 cm/sec. .

[8-2] QF value

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

<Example 1>

The polypropylene [MFR (230 ° C, 21.18 N load) = 30 g/10 min] was melt extruded and ejected from the nozzle holes, and the fiber stream refined by hot air was collected on a roll wound with a transfer net, The first fiber assembly (first fiber layer) having a first surface unevenness and a weight per unit area of 20.0 g/m ² of the melt-blown nonwoven fabric assembly was obtained. The specific conditions of the above melt blowing method are as follows.

. Aperture: 0.4mm

. Hole spacing: 1.50mm

. Spinning temperature: 260 ° C

. Single hole discharge amount: 0.3g / minute. hole

. Hot air temperature: 260 ° C

. Hot air flow: 13Nm ³ /min(1m)

. Distance from nozzle to conveyor: 32cm

. Type of conveyor network: Balance type (width spacing 5mm × length spacing 5mm × thickness 5mm, 1mm ).

Next, polypropylene (MFR (230 ° C, 21.18 N load) = 700 g/10 min] was used, and the meltblown nonwoven fabric aggregate was formed on the first surface unevenness of the first fiber layer according to the following conditions. (1) The second fiber assembly (second fiber layer) having a surface unevenness and a second surface unevenness per unit area of 2.7 g/m ² was obtained, and a fiber laminate was obtained.

. Aperture: 0.3mm

. Hole spacing: 0.75mm

. Spinning temperature: 215 ° C

. Single hole discharge amount: 0.036g / minute. hole

. Hot air temperature: 215 ° C

. Hot air flow rate: 10Nm ³ /min(1m)

. Distance from nozzle to conveyor: 11 cm.

A micrograph of the table of a section of one of the fiber laminates obtained in Example 1 is shown in Fig. 6. It is understood that the first fiber layer has the first surface unevenness, and the second fiber layer has the first surface unevenness and the second surface unevenness. The convex portion constituting the first surface unevenness is a raised convex portion (the same applies to the second to sixth embodiments).

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

. Use solvent: water

. Water pressure: 0.4MPa

. Suction pressure: 2000mmH ₂ O

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

<Example 2>

The 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 conveying net was changed to 15 cm and the unit area was changed to 15.0 g/m ² . Subsequently, a fiber laminate was produced in the same manner as in Example 1.

<Example 3>

In addition to changing the type of conveyor network to balanced (width spacing 2.5mm × length spacing 3mm × thickness 4mm, 0.8mm The 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 conveying net was changed to 20 cm. Subsequently, 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 unit area was changed to 10 g/m ² .

<Example 5>

The 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 conveying net was changed to 25 cm and the unit area was changed to 30.0 g/m ² . Subsequently, 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 transfer net was changed to 40 cm. In the fiber laminate, the first main surface (the first fiber layer side surface) of the second fiber layer has a convex portion height of at most 0.005 mm.

<Comparative Example 1>

In the formation of the first fiber layer, a fiber laminate was produced in the same manner as in Example 1 except that the type of the transfer mesh was changed to a mesh-woven stainless steel mesh of 200 mesh. In the fiber laminate, the first main surface (the second fiber layer side surface) of the first fiber layer and the first main surface (the first fiber layer side surface) of the second fiber layer have a convex portion height of at most 0.005. Mm, compared with the fiber laminate of the example, the pressure loss is high and the QF value is high.

The above [1] to [8] were measured for the fiber laminates obtained in the examples and the comparative examples. The results are shown in Table 1. Further, the air permeability, the collection efficiency, the pressure loss, and the QF value are values after the charging treatment.

1‧‧‧1st fibrous layer

2‧‧‧2nd fibrous layer

11‧‧‧ The first main surface of the first fiber layer (the main surface on the second fiber layer side)

12‧‧‧2nd main surface of the first fibrous layer (main surface opposite to the second fibrous layer)

21‧‧‧ The first main surface of the second fiber layer (the main surface on the first fiber layer side)

22‧‧‧2nd main surface of the 2nd fiber layer

Claims (15)

A fiber laminate comprising: a first fiber layer having a first main surface and comprising a first fiber assembly; and a second fiber layer disposed on the first main surface and comprising a second fiber assembly, wherein At least one of the first main surface and the main surface on the first fiber layer side of the second fiber layer has a first surface unevenness, and the height of the convex portion constituting the first surface unevenness is 0.1 mm or more. The fiber laminate according to claim 1, wherein the density of the convex portions constituting the first surface unevenness is 3/cm ² or more. The fiber laminate according to claim 1, wherein at least the first main surface has the first surface unevenness. The fiber laminate according to claim 1, wherein the main surface of the second fiber layer opposite to the first fiber layer has a second surface unevenness, and the height of the convex portion constituting the second surface unevenness is 0.05 mm or more. The fiber laminate according to claim 4, wherein the density of the convex portions constituting the second surface unevenness is 3/cm ² or more. The fibrous laminate of claim 1, wherein the bulk density is 0.1 g/cm ³ or less. The fiber laminate according to claim 1, wherein a 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. The fiber laminate of claim 1, wherein the aforementioned first fiber set The combined body and the second assembly are nonwoven fabric aggregates. The fiber laminate according to claim 8, wherein the nonwoven fabric assembly comprises a polyolefin resin fiber. The fiber laminate according to claim 1, wherein the fibers constituting the second fiber assembly have an average fiber diameter of 0.5 to 2 μm. The fibrous laminate of claim 1, wherein the air permeability is 100 cc/cm ² /s or more. The fiber laminate according to claim 1, wherein the collection efficiency and the pressure loss measured according to JIS T 8151 are respectively 85% or more and 10 Pa or less, and the QF value calculated according to the following formula is 0.6 or more, and QF value = -ln (1 - capture efficiency (%) / 100) / pressure loss (Pa). A fibrous laminate according to claim 1 which is subjected to a charged processor. The fiber laminate according to any one of claims 1 to 13, which is a filter material. A fiber laminate according to any one of claims 1 to 13, which is a sweeping tool.