JPH06146147A - Nonwoven fabric for cleaner filter and its production - Google Patents

Abstract

PURPOSE:To provide a light nonwoven fabric for a cleaner filter, exhibiting high trapping properties, low in pressure loss and excellent in flexibility, durability, processability, handleability, etc., and to provide its ready production method. CONSTITUTION:This nonwoven fabric for a cleaner filter is composed of a high-density layer made of a modified cross-section ultrafine fiber having <=0.5 denier single yarn fineness and exhibiting >=0.17g/cm<3> density and a low-density layer made of a hydrophobic fiber and exhibiting <=0.15g/cm<3> density. Both the layers are unified into one body by entanglement of constituting fibers and this nonwoven fabric exhibits a density gradient in the cross-sectional direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric for a vacuum cleaner filter and an improvement in its production method.

[0002]

2. Description of the Related Art Conventionally, as a filter for a vacuum cleaner, a napped woven fabric, a needle punched non-woven fabric, a spunbonded nonwoven fabric, a non-woven fabric obtained by combining spunbond and needle punch, and the like are often used.

Further, as a highly-collective non-woven fabric, a non-woven fabric using ultrafine fibers, for example, a non-woven fabric in which ultrafine glass fibers are bonded with a binder, or a non-woven fabric obtained by laminating webs formed by a melt blow method and then needle punching them, has been proposed. ing.

[0004]

However, a filter made of a raised woven fabric, a needle-punched nonwoven fabric, a spunbonded nonwoven fabric, or a nonwoven fabric formed by using a combination of spunbond and needlepunch is used for coarse dust, that is, for filtering dust of 5 μm or more. Although it was possible, it could not be used for filtering fine dust of 1 to 5 μm. In this case, even if the above-mentioned conventional filter is used, fine dust can be filtered by increasing the basis weight.
When the basis weight is increased, the pressure loss becomes large and it cannot be put to practical use. Moreover, since the texture is hard and heavy, the sewing process is difficult and the handleability becomes poor.

Nonwoven fabrics using ultrafine fibers have a single yarn fineness of 0.
If it is less than 8 denier, the permeability in the cotton opening and carding steps becomes a problem, and the nonwoven fabric produced by the melt blow method has a weak tensile strength and is difficult to use alone.

The present invention solves the above conventional problems,
(EN) A non-woven fabric for a vacuum cleaner filter, which is lightweight, has a high collection property, has a small pressure loss, and is excellent in flexibility, durability, processability, and handleability, and a simple production method thereof.

[0007]

The present invention has the following constitution in order to solve the above-mentioned conventional problems. That is, the present invention provides a high-density layer having a density of 0.17 g / cm ³ or more composed of ultrafine fibers of irregular cross section having a fineness of single yarn of 0.5 denier or less, and a low density of 0.15 g / cm ³ or less composed of hydrophobic fibers. A non-woven fabric for a vacuum cleaner filter, characterized in that it is composed of layers, and these two layers are integrated by the entanglement of constituent fibers and have a density gradient in the cross-sectional direction, and a single yarn fineness of 0.5.
A web made of splittable conjugate fibers that can be split into ultrafine fibers of denier or less is laid on a nonwoven fabric made of hydrophobic fibers, and a high-pressure water jet is jetted from the web to split the splittable conjugate fibers and entangle the two layers together. The method for producing a non-woven fabric for a vacuum cleaner filter is characterized in that:

The present invention will be described in more detail. As the ultrafine fibers of irregular cross section having a single yarn fineness of 0.5 denier or less used in the present invention, the ultrafine fibers obtained by dividing the splittable conjugate fiber in the subsequent step are preferably used. To be

The splittable conjugate fibers include those that are chemically split and those that are physically split. In the former, the latter dissolves some of the composite components of the fibers with a chemical agent in the latter step and splits. However, the processing steps are complicated, special processing equipment is required, and there are many problems in terms of stable production.

On the other hand, the latter is divided by means such as high-pressure water flow in the subsequent step, and the processing step is simple and no special processing equipment is required, so that it is industrially advantageous over the former.

As an example of a splittable conjugate fiber which can be physically split, as shown in FIGS. 1 to 4, two incompatible thermoplastic polymers (black portion and white portion) are alternately crossed. The composite fibers arranged in the above are listed. Examples of the combination of two incompatible thermoplastic polymers include polyester and polypropylene, polyester and nylon, nylon and polypropylene, and the like.

The single yarn fineness of the splittable conjugate fiber is preferably about 1 to 5 denier, and the single yarn fineness of the ultrafine fibers after splitting is 0.5 denier or less, preferably 0.2 denier or less.

The reason why the ultrafine fibers used in the present invention have a modified cross section is to improve the trapping effect and the entanglement of the fibers due to the increased surface area of the modified cross section.

The non-woven fabric of the present invention comprises a high-density layer made of ultrafine fibers of irregular cross section and a low-density layer made of hydrophobic fibers. Coarse dust is filtered by the low-density layer, and fine dust is high-density. There is an advantage that the collection efficiency is improved by performing the layer-by-layer collection of filtering by layers, and the pressure loss is reduced even in long-term use.

[0015] The density of the high density layer is 0.17 g / cm ³ or more, preferably 0.2~0.25g / cm ^3,
If it is less than 0.17 g / cm ³ , the effect of collecting fine dust becomes poor. On the other hand, the density of the low density layer is 0.15 g / cm ³ or less, and if it exceeds 0.15 g / cm ³ , the pressure loss becomes too large to be used as a filter for a vacuum cleaner.

As the fibers constituting the low density layer, hydrophobic fibers are preferable, and specifically, polyester fibers, polypropylene fibers, and acrylic fibers having a single yarn fineness of 1 to 5 denier are preferably used.

A heat-fusible fiber is used as a part of the constituent fibers.
By containing 0% or more and performing heat fusion treatment in the subsequent step, the shape stability and durability can be further improved. In this case, as the heat-fusible fiber, a core-sheath composite fiber having a core component having a low melting point component and a sheath component having a high melting point component, for example, core polyethylene / sheath polypropylene, core polyethylene / sheath polyester, core Core-sheath composite fibers such as low-melting point polyester / sheath polyester and core low-melting point polyester / sheath polyamide are preferably used.

In the present invention, the high-density layer has a unit weight of 40 to
100 g / m ² is preferable, and if it is less than 40 g / m ² , the layer becomes non-uniform and the collection efficiency tends to vary. On the contrary, if it exceeds 100 g / m ² , the collection efficiency is improved, but the pressure loss is It becomes large, which is not preferable.

The basis weight of the whole nonwoven fabric is 140 to 400 g.
/ M ² is preferable, and if it is less than 140 g / m ² , there is a problem in shape stability and durability. Conversely, if it exceeds 400 g / m ² , pressure loss becomes too large and there is a problem in sewing processing and handling. There is.

An example of the method for producing the non-woven fabric according to the present invention will be described. First, the hydrophobic fiber (preferably single yarn fineness 1
~ 5 denier) is used to form a needle punched nonwoven fabric, and the number of needle punches in this case is 300 to 40
About 0 points / cm ² is preferable, and if the number is increased and the density is increased too much, the entanglement of the fibers in the subsequent high pressure water treatment becomes insufficient, which is not preferable.

Next, a high-density layer composed of ultrafine fibers is formed. In this case, a mechanically dividable composite fiber as shown in FIGS. 1 to 4 is used to form a web, and this web is needle-punched. By superposing on a non-woven fabric and lightly needle punching or not, by injecting a high-pressure water stream from the splittable conjugate fiber web side, the splittable conjugate fiber is split and the constituent fibers are entangled with each other to achieve a high density. The nonwoven fabric of the present invention is formed by simultaneously forming the layer and integrating the high density layer and the low density layer made of the needle punched nonwoven fabric.

In this case, the high-pressure water flow treatment is very advantageous in providing a density gradient along the thickness direction of the nonwoven fabric.

That is, since the impact force of the high-pressure water flow is the largest on the surface where the high-pressure water flow directly collides, the splittable conjugate fiber is almost completely split, and the constituent fibers are sufficiently entangled with each other to have a high density. Since the impact force becomes weaker toward the inner layer, splitting of the splittable composite fiber becomes insufficient and the entanglement of the constituent fibers also becomes weaker, resulting in a lower density, inevitably increasing the density from the surface of the nonwoven fabric toward the lower layer. A gradient is formed.

The treatment with a high-pressure water stream is performed with a pore size of 0.05 to
Injection pressure of 40-200k using 0.40mm nozzle
The columnar flow is preferably performed at g / mm ² , and the distance between the nozzle and the web to be treated is preferably 1 to 5 cm. If this distance is too large, the high pressure water flow and the air are mixed and the high pressure water flow is mixed. The impact force of is decreased, and the effect of splitting and entanglement of the composite fiber cannot be obtained.

As the support for the web in the high-pressure water flow treatment, a roll-shaped material or a net-shaped material is used, and in the case of the net-shaped material, it is preferable to use a material having a dense structure of 60 mesh or more.

[0026]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the physical properties in the examples are measured by the following methods.

[Unit weight]: According to JIS L-1085.

[Thickness]: JIS L-1085 (load 2
According to 0 g / cm ² ).

[Density]: Calculated by weight (g) / volume (cm ³ ).

[Pressure loss]: The static pressure difference before and after the sample was measured with a U-tube manometer when the sample was set in a duct having a diameter of 10 cm and air was sucked at a wind speed of 1 m / sec.

[Air permeability]: According to JIS L-1096 (Flagille's method).

[Collection efficiency]: A linear velocity of 5 cm in Portland
The concentration ratio between the upstream side and the downstream side of the filter when supplied to the test filter at 1 / sec is measured by a gravimetric method.

Example 1 Polyethylene terephthalate having an intrinsic viscosity of 0.63 (measured in orthochlorophenol at 25 ° C.) and MI10 (ASTM D-1238 2)
(30 ° C.) polypropylene was melt-composited at a volume ratio of 1: 2 to obtain a splittable composite undrawn yarn having a cross section shown in FIG. The unstretched yarns are drawn together and drawn at a stretching temperature of 80 ° C for 3.5
After being double-stretched to have a single yarn fineness of 2 denier, 20 crimps / inch of crimps are continuously applied by a crimping machine, and then relaxation heat treatment is performed in an autoclave at 120 ° C. for 10 minutes, and then a length of 38 mm. It was cut into splittable conjugate short fibers, and using this splittable conjugate short fiber, a card web having a basis weight of 50 g / m ² was formed.

On the other hand, polyester short fibers (2 denier x
51 mm) 80%, polyethylene terephthalate as the core, and 20% of the heat-fusible composite fiber as the sheath, which is a modified polyester having a melting point of 120 ° C., to form a needle-punched mixed nonwoven fabric having a density of 0.11 g / cm ³ .

Then, the separable composite short fiber web was laminated on the mixed non-woven fabric and placed on a 100-mesh net conveyer, and the hole diameter was 0.13 mm and the hole interval was 1 mm from the side of the separable composite short fiber web. 20k with nozzle
A columnar flow of 4-stage water was jetted at a pressure of g / mm ² , 30 kg / mm ² , 80 kg / mm ² , and 100 kg / mm ² to split the splittable composite short fibers and entangle the constituent fibers. It was then dried and subjected to heat fusion treatment at 150 ° C.

The fineness of the ultrafine fibers after division is 0.12 denier for polyester fibers and 0.
It was 14 denier. Also, when observing the non-woven fabric with an electron microscope, the surface part is a high-density layer in which completely divided ultrafine fibers are entangled with each other, and in the part close to the middle layer part, the completely divided ultrafine fibers and the division are incomplete. Fiber, and a layer in which the polyester fiber and the polyester heat-fusible composite fiber of the lower layer are mixed, the lowest layer is a low density layer consisting of polyester fiber and polyester heat-fusible composite fiber, from the surface to the lower layer It was a non-woven fabric with a density gradient toward. The physical properties of the obtained non-woven fabric are shown in Table 1.

Example 2 Each of the non-woven fabrics obtained by the same treatment as in Example 1 except that a web having a basis weight of 80 g / m ² was used instead of the web having a basis weight of 50 g / m ² made of splittable composite short fibers. The physical property values are also shown in Table 1.

(Comparative Examples 1, 2, 3) Nonwoven fabric formed in the same manner as in Example 2 except that the densities of the high-density layer and the low-density layer were changed (Comparative Example 1), the same as that used in Example 1. Table 1 also shows the physical properties of the non-woven fabric composed of the splittable composite staple fibers (Comparative Example 2) and the needle-punched non-woven fabric composed of the commercially available polyethylene terephthalate fiber (Comparative Example 3).

[0039]

[Table 1]

(Example 3) 120 g of a basis weight consisting of 80% polyester short fibers (2 denier x 51 mm) and 20% heat-fusible composite fiber whose core is polyethylene terephthalate and whose sheath is a modified polyester having a melting point of 120 ° C. / M ² of a card web is formed, and a basis weight of 30 g /
m ² corbags (trade name of spunbonded nonwoven fabric manufactured by Akzo Co., Ltd.) were superposed and temporarily joined by needle punching.

Then, the same splittable composite short fibers as used in Example 1 were used to form a card web having a basis weight of 60 g / m ² , and this web was laid on the above temporarily bonded nonwoven fabric to form a splittable composite. From the short fiber web side, a water columnar flow was jetted at a pressure of 120 kg / mm ² .

The obtained non-woven fabric was a three-layer non-woven fabric composed of a surface layer made of ultrafine fibers, a middle layer made of spunbonded non-woven fabric, and a lower layer made of polyethylene terephthalate fiber and heat-adhesive fiber. m ² ,
The surface layer has a density of 0.21 g / cm ³ , and the lower layer has a density of 0.1.
4 g / cm ³ , air permeability was 35 cc / cm ² / sec, and when used as a vacuum cleaner filter at a wind speed of 10 m / min, the collection efficiency of dust of 2 μm or more was 99.9% or more. .

Further, this non-woven fabric was excellent in that it had little pressure loss even when it was used as a filter for a commercial vacuum cleaner for both wet and dry use and did not deteriorate in performance even after repeated use such as washing with water.

[0044]

EFFECT OF THE INVENTION The nonwoven fabric of the present invention constructed as described above is light in weight and has a high trapping property while having a small pressure loss.
Moreover, it is a non-woven fabric having excellent flexibility, durability, processability, and handleability, and has excellent suitability for a vacuum cleaner filter.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a splittable conjugate fiber used in the present invention.

FIG. 2 is a cross-sectional view showing another example of the splittable conjugate fiber used in the present invention.

FIG. 3 is a cross-sectional view showing another example of the splittable conjugate fiber used in the present invention.

FIG. 4 is a cross-sectional view showing another example of the splittable conjugate fiber used in the present invention.

Claims (2)

[Claims] 1. A high-density layer having a density of 0.17 g / cm ³ or more composed of ultrafine fibers of irregular cross section having a single yarn fineness of 0.5 denier or less, and a low density of 0.15 g / cm ³ or less composed of hydrophobic fibers. A non-woven fabric for a vacuum cleaner filter, which is composed of layers, and both layers are integrated by entanglement of constituent fibers and have a density gradient in a cross-sectional direction. 2. A web composed of separable conjugate fibers that can be divided into ultrafine fibers having a single yarn fineness of 0.5 denier or less is superposed on a nonwoven fabric composed of hydrophobic fibers, and a high-pressure water stream is jetted from the web to divide the fibers. A method for producing a nonwoven fabric for a vacuum cleaner filter, characterized in that the functional composite fiber is divided and both layers are entangled and integrated.