JP2000201869A - Dust collection bag for vacuum cleaner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dust collection bag for a vacuum cleaner which is capable of maintaining performance of a high capturing characteristic for a long period of time with the low pressure drop based on an electret melt flow nonwoven fabric. SOLUTION: This dust collection bag for a vacuum cleaner consists of a laminate 10 of at least two layers laminated with an inner layer 1 and an outer layer 3 in this order in a pass direction of suction air. The inner layer 1 is the electret melt flow nonwoven fabric formed of an upstream side fiber layer 1a having an average monofilament diameter of 2.5 to 20 μm and a downstream side fiber layer 1b having an average monofilament diameter of 0.7 to 2.4 μm in such a manner that the average pore diameter over the entire part of the inner layer is 10 to 30 μm and that the maximum pore diameter thereof is <=45 μm. The outer layer 2 of the dust collection bag for the vacuum cleaner consists of the nonwoven fabric having rupture strength of >=1.5 kg/cm3 (14.7 N/cm2), strength of >=1.5 kg/50 mm (14.7 N/50 mm) at 1% elongation, METSUKE (unit) of 10 to 50 g/M2 and a ventilation rate of >=70 cc/cm2/sec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust-collecting bag for a vacuum cleaner, and more particularly to a dust-collecting bag for a vacuum cleaner capable of maintaining excellent performance with low pressure drop and high collecting performance for a long period of time.

[0002]

2. Description of the Related Art Conventionally, as a disposable dust bag attached to a vacuum cleaner, a paper-made bag mainly made of pulp is often used from the viewpoint of cost. However, paper dust bags reduce dust collection performance when trying to reduce the load on the vacuum cleaner in order to reduce the pressure loss of suction air, and conversely to improve the dust collection performance. Then
As a result, the pressure loss is increased and the load of the vacuum cleaner is increased, so that the pressure loss and the trapping performance have an incompatible relationship with each other.

In order to solve such a problem, an electret melt-blown nonwoven fabric having a dust-absorbing property based on an electret effect is used as a main material of a filter medium, so that a dust-collecting bag having a high collection performance with low pressure loss. Has been proposed. However, since the electret meltblown nonwoven fabric is composed of a collection of unstretched yarns having low strength, it can be opened over time by high-pressure suction air during use, or can be damaged by collision of large dust. is there.

[0004] Japanese Patent Publication No. 4-35205 proposes a dust-collecting bag in which a pulp filter paper having a dense structure is laminated on an electret melt-blown nonwoven fabric to compensate for insufficient strength. However, in the vacuum cleaner at that time, column 5 of the publication 22
As described in lines 23 to 23, almost satisfactory performance was obtained even when pulp filter paper was laminated, since the collection performance was at a suction air velocity of 1.5 m / min. Therefore, since a stronger suction air velocity is used, when the pulp filter paper is laminated as described above, clogging occurs at an early stage, and there is a problem that the performance of the electret melt-blown nonwoven fabric is reduced.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dust collecting bag for a vacuum cleaner which can maintain excellent performance based on electret meltblown nonwoven fabric for a long period of time.

[0006]

According to a first aspect of the present invention, there is provided a dust collecting bag for an electric vacuum cleaner, comprising at least two layers, an inner layer and an outer layer, which are stacked in the suction air passage direction. From the upstream fiber layer having an average single fiber diameter of 2.5 to 20 μm and the downstream fiber layer having an average single fiber diameter of 0.7 to 2.4 μm, the average pore diameter of the entire inner layer is 10 to 30 μm,
An electret meltblown nonwoven fabric formed to have a maximum pore size of 45 μm or less, wherein the outer layer has a burst strength of 1.5 kg / cm ² (14.7 N / cm ² ) or more,
Strength at 1% elongation 1.5kg / 50mm (14.7N / 50mm)
As described above, the basis weight is 10 to 50 g / m ² , and the air permeability is 70 cc / cm.
It is a nonwoven fabric of ² sec or more.

As described above, the inner layer has an average pore diameter of 10 to 30 μm.
m, an electret meltblown nonwoven fabric having a maximum pore diameter of 45 μm or less was used, and the outer layer had a basis weight of 10 to 50 g /
By laminating a nonwoven fabric having m ² and a ventilation rate of 70 cc / cm ² · sec or more, a low pressure loss and a high trapping property can be exhibited by making use of the performance based on the inner layer electret melt blown nonwoven fabric.

Further, the electret meltblown nonwoven fabric has at least a two-layer structure, and the upstream fiber layer has a relatively large fineness having an average single fiber diameter of 2.5 to 20 μm.
Since the downstream fiber layer is composed of ultrafine fibers having an average single fiber diameter of 0.7 to 2.4 μm, large-sized dust is trapped in advance by the upstream fiber layer, and the downstream fiber layer functioning as a main filter medium may be damaged. Absent. Further, a burst strength of 1.5 kg / cm ² (14.7 N / cm ² ) or more and 1%
Since a tough nonwoven fabric having a strength of 1.5 kg / 50 mm (14.7 N / 50 mm) or more at the time of elongation was arranged as an outer layer, the wind speed was 12 m.
Even when high-pressure air exceeding / min is applied, it is possible to prevent the opening of the electret melt-blown nonwoven fabric of the inner layer and to maintain the original high collecting performance and low pressure loss performance of the electret meltblown nonwoven fabric for a long period of time. it can.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a filter material constituting a dust collecting bag for a vacuum cleaner is composed of a laminate of at least two layers of nonwoven fabric laminated in order of an inner layer and an outer layer in a direction of passage of suction air. I have.

FIG. 1 is a cross-sectional view of an essential part showing an example of a laminated body constituting a dust bag according to the present invention. The laminated body 10 has an inner layer 1 in a direction in which suction air passes (a direction indicated by an arrow). The nonwoven fabric and the nonwoven fabric of the outer layer 2 are sequentially laminated.

Of these inner and outer nonwoven fabrics, the inner layer 1 has, for example, a surface charge density of 1 × 10 ⁻¹⁰ coulomb / cm ² or more,
More preferably, it is composed of an electret melt-blown nonwoven fabric of 3 × 10 ⁻¹⁰ coulomb / cm ² or more. Moreover, this electret meltblown nonwoven fabric has an upstream fiber layer 1a made of relatively thick fibers having an average single fiber diameter of 2.5 to 20 μm, and an average single fiber diameter of 0.7 to 2.0.
And a downstream fiber layer 1b made of 4 μm ultrafine fibers.

As described above, the electret meltblown nonwoven fabric of the inner layer 1 has an upstream fiber layer 1a composed of fibers having a large fineness having an average single fiber diameter of 2.5 to 20 μm and an ultrafine fiber having an average single fiber diameter of 0.7 to 2.4 μm. Downstream fiber layer 1 made of fiber
b and at least two layers. Moreover, the inner layer 1 is configured to have pores having an average pore diameter of 10 to 30 μm as a whole and a maximum pore diameter of 45 μm or less.

If the average pore diameter of the entire inner layer is smaller than 10 μm, the air permeability is reduced and the pressure loss is increased, making it difficult to achieve the object of the present invention. Also,
If the average pore diameter is larger than 30 μm, it becomes difficult to collect fine dust and dirt, and the collection performance targeted by the present invention is reduced. On the other hand, if the maximum pore diameter is larger than 45 μm, the dust collecting power due to the electret effect is limited, so that the collecting performance is reduced and dust easily leaks into the air exhausted from the vacuum cleaner.

In the electret meltblown nonwoven fabric used in the present invention, the downstream fiber layer composed of ultrafine fibers having an average single fiber diameter of 0.7 to 2.4 μm functions as a main element for collecting fine dust and fine dust. On the other hand, the upstream fiber layer made of a thick fiber having an average single fiber diameter of 2.5 to 20 μm has a large strength, and thus has a protective action against deformation of the downstream fiber layer and a collecting action of medium dust and coarse dust. I do. That is, the upstream fiber layer collects in advance large dusts in the air that first enter the dust bag, so that the filtration area of the downstream fiber layer that performs the main filtering action is not reduced.

When the average single fiber diameter of the fibers constituting the downstream fiber layer is less than 0.7 μm, the air permeability decreases, which causes an increase in pressure loss. Although it is advantageous from the viewpoint of controlling the pore diameter to make the diameter smaller than 0.7 μm, it is very difficult to produce such an ultrafine fiber from the viewpoint of the production technique, which results in an increase in cost. Also,
When the average single fiber diameter of the fibers in the downstream fiber layer is larger than 2.4 μm, the action of collecting fine dust and fine dust becomes difficult, and high collecting performance cannot be obtained.

In the present invention, the average pore diameter of the entire inner layer is 10 to 30 μm, and the maximum pore diameter is 45 μm.
Although it will be described below, it is preferable that the average pore diameter of the downstream fiber layer 1b that performs the main trapping action is 10 to 35 μm and the maximum pore diameter is 50 μm or less. It is preferable that the formation of the downstream fiber layer is as uniform as possible, and the total unevenness (unevenness CV
Value) is set to 8% or less, preferably 6% or less, and more preferably 5% or less.

The air permeability of the electret meltblown nonwoven fabric of the inner layer is 10 to 50 cc / c for the entire inner layer.
m ² · sec is preferred, but 15 m for the downstream fiber layer alone.
It is preferable to set it to 80 cc / cm ² · sec. Moreover, to meet such aeration rate, basis weight of the electret melt blown nonwoven fabric, the entire inner layer to 12~50g / m ^2, it is preferable to 8 to 20 g / m ² on the downstream side fiber layer alone.

On the other hand, the upstream fiber layer of the electret meltblown nonwoven fabric has an average single fiber diameter of 2.5 as described above.
As long as the thickness is in the range of ２０20 μm, it may be a single layer or a plurality of layers. When the upstream fiber layer has a plurality of layers, a two-layer structure in which a layer having an average single fiber diameter of 5 to 20 μm is arranged upstream and a layer having an average single fiber diameter of 2.5 to 5 μm is arranged downstream is preferable. By adopting such a two-layer structure, it is possible to enhance compatibility between the function of protecting the downstream fiber layer and the function of collecting medium dust and coarse dust. Further layers may be used, but from the viewpoint of cost, it is better to limit the number to about three layers.

The basis weight of the upstream fiber layer is 12 to 5
Against 0 g / m ^2, and in the range of 10 to 40 g / m ^2,
Preferably, it is 15 to 35 g / m ² . When the basis weight of the upstream fiber layer is less than 10 g / m ² , the protective effect on the downstream fiber layer is reduced. In addition, 40 g / m ²
If it is larger than this, the dust collecting bag becomes thicker and the bag-making processability deteriorates.

As described above, a method for producing an electret melt-blown nonwoven fabric comprising at least two layers of a downstream fiber layer and an upstream fiber layer having different average single fiber diameters includes, for example, a method in which a single fiber A method in which the diameter is changed in multiple stages and collected so that the layers are stacked in a multi-stage manner. Also, two or more layers of melt-blown non-woven fabrics having different single fiber diameters are sintered by interposing a resin between the respective layers, and hot melt. There is a method of processing or embossing and bonding them together. However, among these methods, the method of changing the fineness during direct melt blow spinning to collect and collect in multiple stages is the simplest and preferable method.

As a processing method for converting the melt blown nonwoven fabric into an electret, any conventionally known method can be used, and there is no particular limitation. For example, a melt-blown non-woven fabric is supplied to the upper surface of a drum-shaped ground electrode,
Further, a wire electrode is placed 3 to 10 cm above the non-woven fabric, and a direct current of 10
When a high voltage of about 40 kv is applied for about 1 to 10 seconds, the melt blown nonwoven fabric can be made into an electret.

The resin constituting the electret melt-blown non-woven fabric is not particularly limited. Examples thereof include polyolefins (eg, polypropylene, polyethylene, and polystyrene), polyamides, polyesters, fluororesins, polycarbonates, polyacrylonitriles, and vinyl chlorides having a volume resistivity of 10%. Those having a resistance of ¹² Ω · cm or more can be given. Of these, polyolefins that can be easily electretized, particularly polypropylene, are preferred.

In the present invention, the outer layer laminated on the outside of the above electret meltblown nonwoven fabric has a burst strength of 1.5 kg / cm ² (14.7 N / cm ² ) or more, and
1.5kg / 50mm (14.7N / 50mm)
In addition to the above, a nonwoven fabric having a basis weight of 10 to 50 g / m ² and a ventilation rate of 70 cc / cm ² · sec or more is used. By arranging the outer layer non-woven fabric on the downstream side of the electret melt-blown non-woven fabric, the electret melt-blown non-woven fabric consisting of an aggregate of unstretched yarns having low strength is protected against a continuous load of high-pressure suction air. Melt blown nonwoven fabric opens,
Avoid damage. By such a protective action of the outer layer, the electret meltblown nonwoven fabric can maintain the initial high collection performance for a long period of time.

In order to protect the outer layer, the nonwoven fabric used for the outer layer has a burst strength of 1.5 kg / cm ² (14.
7 N / cm ² ) or more, preferably 2.0 kg / cm
² (19.6 N / cm ² ) or more. Also,
It is necessary to make it difficult to elongate.
5 kg / 50 mm (14.7 N / 50 mm) or more, more preferably 2.0 kg / 50 mm (19.6 N / 50 mm) or more, and even more preferably 2.5 kg / 50 mm (24.5 N / 50 mm).
It is better to do above.

The nonwoven fabric used for the outer layer further has a basis weight of 20 to 50 g / m ² and an air permeability of 70 cc / cm ² · s.
ec or more. These properties are important for maintaining low pressure loss and high collection performance of the electret meltblown nonwoven fabric. When the basis weight is less than 20 g / m ² , density unevenness tends to occur in the production of the nonwoven fabric, and it becomes difficult to obtain the above-described burst strength. Also, the basis weight is 50 g /
If it is larger than m ² , processing of the dust collection bag becomes difficult because the thickness becomes large.

The type of nonwoven fabric used for the outer layer is not particularly limited. A dry nonwoven fabric using various synthetic fibers, natural fibers or a mixed fiber thereof, a wet nonwoven fabric by a papermaking method, a spunbonded nonwoven fabric of various synthetic fibers, and the like are preferably used. Among these, a wet nonwoven fabric by a papermaking method, in which particularly high strength at 1% elongation is easily obtained, is suitable as the outer layer.

In the present invention, when a wet nonwoven fabric by a papermaking method is used as the inner layer or the outer layer, a paper strength enhancer can be added in addition to the main fiber as a usual method. For example, PVA, epoxy resin, CMC, cationized starch and the like are used, and strength, elongation, hardness and the like can be adjusted.

In the dust collecting bag of the present invention, it is sufficient to use a laminate of the above-mentioned inner layer electret meltblown nonwoven fabric and another nonwoven fabric which protects the same with an outer layer. The effect can be further improved by adopting a structure in which another nonwoven fabric other than the electret meltblown nonwoven fabric is arranged as the auxiliary layer.

The auxiliary layer disposed inside the inner layer has a breaking strength of 0.7 kg / 50 mm (6.9 N / 50).
mm) or more. This nonwoven fabric collects especially large-mass dust among the dust that first enters the dust collection bag, and prevents the large dust from opening the inner layer electret meltblown nonwoven fabric or reducing the filtration area. To prevent.

That is, as described above, since the inner layer electret meltblown nonwoven fabric is composed of an aggregate of low-strength undrawn yarns, when large-mass dust directly collides with the inner layer, it is easily opened and trapped. The collection performance will be reduced. Further, when large dust is directly captured by the inner electret meltblown nonwoven fabric, the filtration area is sharply reduced, and the pressure loss is increased.

In order to enable the function of the auxiliary layer as described above, the non-woven fabric of the auxiliary layer has a breaking strength of 0.7 kg / 50 mm.
(6.9 N / 50 mm) or more, preferably 1.0 kg / 50
mm (9.8 N / 50 mm) or more, more preferably 1.
It is preferable that the pressure be 5 kg / 50 mm (14.7 N / 50 mm) or more. Further, if the 1% elongation strength of the auxiliary layer is set higher than that of the electret meltblown nonwoven fabric of the inner layer, the protective action can be further improved.

The auxiliary layer has a basis weight of 10 to 10.
50 g / m ² , air flow rate is 100 cc / cm ² · sec
It is preferable to use the above-mentioned nonwoven fabric having good air permeability.
If the basis weight is less than 10 g / m ² , the non-woven fabric tends to have uneven density and the breaking strength tends to fluctuate. On the other hand, when the basis weight is more than 50 g / m ² , the thickness becomes large, and it becomes difficult to process the dust bag.

As the type of nonwoven fabric used for the auxiliary layer,
Although not particularly limited, like the nonwoven fabric used for the outer layer,
For example, a dry nonwoven fabric using various synthetic fibers, natural fibers or a mixed fiber thereof, a wet nonwoven fabric by a papermaking method, a spunbonded nonwoven fabric of various synthetic fibers, and the like can be preferably used.

The auxiliary layer is preferably bonded to the inner layer electret meltblown nonwoven fabric with an adhesive or a fusion fiber. Further, if at least one of the nonwoven fabric of the auxiliary layer and the outer layer is electretized, the effect of the present invention can be further improved.

Since various bacteria, molds, ticks, etc. are collected in the above-mentioned dust collecting bag for a vacuum cleaner, at least one of the inner layer, the outer layer or the auxiliary layer, or all the layers, is subjected to antibacterial treatment or / and And it is beneficial to apply mite control. In particular, it is preferable to process the inner layer and the auxiliary layer to which a large amount of dust adheres.

These antibacterial and mite-proof processing methods,
As the antibacterial agent and the anti-mite agent used in these processes, any of conventionally known ones can be used, and there is no particular limitation. As a processing method, an antibacterial agent, a fungicide,
Even with a method of surface treatment or impregnation with an anti-mite agent,
Alternatively, a method of kneading the fibers constituting the nonwoven fabric at the time of molding such as spinning may be used.

Examples of the antibacterial agent include p-chlorometacresol, p-chloro-m-xylenol, o-phenylphenol, α-promsinnamaldehyde, 2.
4.4'-trichloro-2'-hydroxydiphenyl ether, N- (fluorodichloromethylthio) -phthalimide, N, N-dimethyl-N'-phenyl- (N
-Fluorodichloromethylthio) -sulfamide, 2-
(4-thiazolyl) benzimidazole, chlorhexidine, quaternary ammonium salt, 8-oxyquinoline copper,
Examples thereof include 2-pyridinethiol-1-oxide salts. These may be used alone or in combination of two or more.

Examples of the acaricide (pesticide) include, for example, pyrethrin, artemisia extract, allethrin, d-allethrin, permethrin, phenothrin, resmethrin,
pyrethroid compounds such as d-resmethrin, phthalthrine, framethrin, papersulin and cyphenothrin; fenitrothion, diazinon, fenthion,
Organic phosphorus compounds such as carglophos, cyanophos, dichlorvos, temefos, naled, trichlorfon, fenclofos, malathion, pyridafenthion; and carbamate compounds such as carbaryl, propoxer, and dimethylene. These may be used alone or in combination of two or more.

[0039]

EXAMPLES In the examples described below, physical properties and performance were measured by the following methods.

[Pore size] Filter media performance test Measured by the bubble point method. Using a "porous material automatic pore measuring system Perm-Porometer" (manufactured by Porus Materials, USA) as the measuring instrument, the measuring sample diameter was 21 mm, and the perfluoroamine compound "Fluorinert (inert liquid) FC-40" was used as the measuring solution. 16 dynes / cm ”(manufactured by Sumitomo 3M Limited) was used to measure the pore distribution.

A mean flow pore diameter (MEAN FLOW PORE DIAMETER) obtained as a result of automatic calculation by a measuring instrument under the above conditions is defined as an average pore diameter, and a bubble point pore diameter (BUBBLE) is used. POINT POR
E DIAMETER) was taken as the maximum pore diameter. In addition, five samples were arbitrarily sampled and measured from one sample, and the average value was used.

[Break strength, strength at 1% elongation] JIS L
It was measured according to the rules of 1906. The average value of the measured intensities in the vertical and horizontal directions was used.

[Burst Strength] Measured according to the Mullen-type method of JIS L1906.

[Average Single Fiber Diameter] The fibers were photographed in an enlarged scale with a SEM photograph, and the width of 100 fibers was measured.

[Density] A 0.5 m square sample was weighed and converted to a 1 m square weight.

[Unevenness CV value] A 100 cm square sample was cut into 20 sections each in the vertical and horizontal directions (400 sheets in a 5 cm square), the weight was measured, and analyzed by a two-way arrangement unevenness analysis method to show the total unevenness. .

[Aeration rate] Measured by the Frazier method according to JIS L1096.

[Capture rate] Using a particle counter manufactured by Rion Co., Ltd., the measurement wind speed was set to 12 m / min, the dust was set to the atmospheric dust, and the amount of dust trapped on the filter cloth with respect to the supplied dust amount was measured. The ratio was represented by a ratio (%), and was shown in the following three types according to the particle size of the dust. The number of N was set to 10, and the average value was used.

0.3: Particle size 0.3 μm or more, 0.5 μm
Collection rate of dust having a particle diameter of 0.5 m or more and less than 1.0 μm 1.0: Collection rate of dust having a particle diameter of 1.0 or more [Pressure loss] Filtration A sample filter cloth having an area of 100 cm ² was set, and the pressure difference between the upstream and downstream of the sample filter cloth when air containing air dust was passed through the sample filter cloth at a wind speed of 12 m / min was indicated in mmAq. . N number is 10
And the average value was used.

Examples 1 to 5 and Comparative Examples 1 and 2 A laminate (Example 1, Comparative Example 1,
With respect to 2) and the laminate of the inner layer and the outer layer, laminates (Examples 2 to 5) in which another nonwoven fabric was further laminated inside the inner layer as an auxiliary layer were prepared. Note that Comparative Example 2 is based on the filter described in Japanese Patent Publication No. 4-35205.

The initial pressure loss and trapping rate of each of the above laminates were measured. In addition, each of the laminates is formed into a dust bag, and each of the laminated bodies is actually manufactured (National Canister MC-L
51P vacuum cleaner), the practicality such as bag strength was examined, and the pressure loss and trapping rate after a total of 48 hours of idling were measured. Furthermore, the state of breakage of the dust bag when 100 hexagonal nuts of M5 specified by JIS were blown (nut blowing test) was examined. Table 1 shows the results.

(Example 1) Inner layer: The downstream layer in the suction air passage direction has an average single fiber diameter of 1.7 μm, a basis weight of 15 g / m ² , and an air permeability of 42 cc / cm.
² · sec, unevenness CV value is 3.2%, and the upstream layer is
Average single fiber diameter 7.2 μm, basis weight 32 g / m ² , air permeability 2
A melt-blown nonwoven fabric having a two-layer structure obtained by directly fabricating a two-layer structure with polypropylene and melt-blowing so as to have a two-layer structure of 20 cc / cm ² · sec and an uneven CV value of 3.5%, and electret processing the average pore diameter / maximum pore diameter = 21/32 (μm) (unevenness C
V value: 3.7%) Outer layer: polyester-based heat-fused fiber / pulp = 80/20
(Wt%) Wet nonwoven fabric Tear strength 3.3 kg / cm ² , Strength at 1% elongation 4.1 k
g / cm ² , basis weight 35 g / m ² , air permeability 120 cc / c
m ² · sec

(Example 2) Inner layer: Same as the inner layer of Example 1 Outer layer: Same as the outer layer of Example 1 Auxiliary layer: Polypropylene / spunbond nonwoven fabric Weight: 25 g / m ² , Air permeability: 463 cc / cm ² · se
c, breaking strength 4.5 kg / 50 mm, (average single fiber diameter 28
μm)

(Example 3) Inner layer: Same as the inner layer of Example 1 Outer layer: Same as the outer layer of Example 1 Auxiliary layer: Nonwoven fabric obtained by subjecting the auxiliary layer of Example 2 to electret processing

(Example 4) Inner layer: Same as the inner layer of Example 1 Outer layer: Same as the outer layer of Example 1 Auxiliary layer: The auxiliary layer of Example 2 was treated with the following antibacterial and fungicide and then electret processed. Nonwoven Fabric 6 parts of p- (chlorophenyldiguanide) -hexane as an antibacterial agent, 2 parts of 2- (Nnbutylcarbamic acid 3-9 iodo-2-provinyl ester as a fungicide, 2 parts
Using 1 part of-(4-thiazolyl) benzimidazole, 8 parts of chlorinated polyolefin (15.8% by weight chlorinated polypropylene) as a fixing agent, and toluene as a solvent,
Adjust the liquid concentration to achieve a total dry pickup of 3.5
%, Gravure coated, and 8
Drying treatment was performed at 0 ° C. for 60 seconds.

(Example 5) Inner layer: Same as the inner layer of Example 1 Outer layer: Same as the outer layer of Example 1 Auxiliary layer: Polypropylene-based heat-bonded fiber having a fineness of 28 μm /
8 μm fineness polypropylene fiber / pulp = 55/3
5/15 (% by weight) non-woven fabric obtained by electretizing a wet non-woven fabric by the shaun paper method with a basis weight of 15 g / m ² and a ventilation volume of 180 cc / cm ² · se
c, breaking strength 2.1 kg / 50 mm,

(Comparative Example 1) Inner layer: single layer polypropylene / electret meltblown nonwoven fabric Average single fiber diameter: 1.25 μm, average pore diameter / maximum pore diameter =
33/48 (μm) (basis weight 15 g / m ² , ventilation volume 38 c
c / cm ² · sec, uneven CV value 10.2%) Outer layer: polyester heat-fusible fiber / pulp = 80/20
(Wt%) Wet nonwoven fabric Tear strength 3.3 kg / cm ² , Strength at 1% elongation 4.1 k
g / 50mm, basis weight 35g / m ² , air permeability 120cc / cm
² · sec

(Comparative Example 2) Inner layer: single-layer polypropylene / electret meltblown nonwoven fabric Average single fiber diameter: 1.25 μm, average pore diameter / maximum pore diameter =
11/17 (μm) (basis weight 35 g / m ² , air flow rate 5 cc)
/ Cm ² · sec, uneven CV value 3.6%) Outer layer: same as the outer layer in Example 1 Auxiliary layer: the same as the auxiliary layer in Example 2

[0059]

[Table 1]

From the results shown in Table 1, the dust collecting bags of Examples 1 to 5 had an initial pressure loss performance of about 9 to 10 mmAq, and increased about 2 mmAq after 48 hours. In addition, the initial performance is about 75% or more in all the performances of 0.3, 0.5, and 1.0 in the collection rate, and the performance is almost maintained after 48 hours. No abnormality occurred in the dust bag in both the practicality test and the nut suction test.

On the other hand, in Comparative Example 1, although there was no problem with respect to the pressure loss, the trapping rate was slightly low, and in the nut suction test, breakage occurred and dust leakage occurred. In Comparative Example 2, the pressure loss was very high. Perhaps because of this, the inhalability gradually decreased over time.

[0062]

As described above, according to the present invention, the inner layer is made of an electret melt-blown nonwoven fabric having an average pore diameter of 8 to 30 μm and a maximum pore diameter of 45 μm or less and having a low pressure loss and a high trapping property. By laminating a non-woven fabric having a basis weight of 10 to 50 g / m ² and a gas permeability of 70 cc / cm ² · sec or more, high collecting performance can be obtained with low pressure loss based on electret melt-blown non-woven fabric.

Furthermore, since the inner layer made of electret melt-blown nonwoven fabric has at least two layers and the upstream fiber layer has a relatively large fineness having an average single fiber diameter of 2.5 to 20 μm, large dusts are captured in advance and averaged. The main filter medium of the downstream fiber layer made of ultrafine fibers having a single fiber diameter of 0.7 to 2.4 μm is not damaged, and the outer layer outside the inner layer has a burst strength of 1.5 kg / cm ² (14.7 N / cm).
² ) Above 1% elongation strength 1.5kg / 50mm (14.7)
N / 50mm) or more,
It can prevent the inner layer electret melt-blown nonwoven fabric from opening or bursting over time due to high-pressure suction air pressure, and maintain the high collection performance and low pressure loss initial performance obtained based on the electret meltblown nonwoven fabric for a long time. Can be.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an essential part of an example of a laminated body constituting a dust collecting bag for a vacuum cleaner according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner layer 1a Upstream fiber layer 1b Downstream fiber layer 2 Outer layer 10 Laminate

Claims (8)

[Claims] 1. An at least two-layer laminate in which an inner layer and an outer layer are laminated in the direction of passage of suction air, wherein the inner layer has an upstream fiber layer having an average single fiber diameter of 2.5 to 20 μm and an average single fiber diameter of 0 to 20 μm. From 0.7 to 2.4 μm of the downstream fiber layer, the average pore diameter of the entire inner layer is 10 to 30 μm, and the maximum pore diameter is 4
An electret meltblown nonwoven fabric formed to have a burst strength of 1.5 k or less.
g / cm ² (14.7 N / cm ² ) or more, strength at 1% elongation 1.5 kg / 50 mm (14.7 N / 50 mm) or more, basis weight 1
A dust-collecting bag for a vacuum cleaner, which is a nonwoven fabric having a volume of 0 to 50 g / m ² and an air permeability of 70 cc / cm ² · sec or more. 2. The weight of the inner layer is 12 to 50 g / m ² ,
The dust bag for an electric vacuum cleaner according to claim 1, wherein the ventilation amount is 10 to 50 cc / cm ² · sec. 3. The inner weight of the inner layer is 10 to 50 g / weight.
The auxiliary layer according to claim 1 or 2, wherein an auxiliary layer made of a nonwoven fabric other than an electret meltblown nonwoven fabric having an m ² , an air permeability of 100 cc / cm ² · sec or more, and a breaking strength of 0.7 kg / 50 mm (6.9 N / 50 mm) or more is arranged. Dust bag for vacuum cleaner. 4. The dust bag according to claim 3, wherein the auxiliary layer and the inner layer are adhered to each other. 5. The dust bag for a vacuum cleaner according to claim 1, wherein at least one of the auxiliary layer and the outer layer is formed as an electret. 6. The dust bag for a vacuum cleaner according to claim 1, wherein at least one of antibacterial processing and mite prevention processing is applied to at least the auxiliary layer. 7. The dust bag for an electric vacuum cleaner according to claim 1, wherein the inner layer is made of a polypropylene resin. 8. The dust bag for a vacuum cleaner according to claim 1, wherein the outer layer and the auxiliary layer each comprise at least 50% by weight of a polypropylene resin.