JPH04180808A - Molded filter - Google Patents

Abstract

PURPOSE:To ensure the maintenance of the long life, efficient dust removal and high shape-retaining properties of a filter by laminating an extremely fine unwoven cloth of specific average fiber diameter and bulk density and a fiber sheet of specific average fiber diameter and bulk density, and forming the laminated product into recessed and projecting shapes of specific height. CONSTITUTION:Extremely fine unwoven cloth (b) with an average fiber diameter of 0.5 to 6.0mum and a bulk density of 0.05 to 0.50g/cm<2>, and fibrous sheets (a, c) consisting of aromatic polyester long fiber with an average fiber diameter of 10 to 60mum and a bulk density of 0.05 to 0.50g/cm<2> on one side or both sides of said extremely fine unwoven cloth (b), are laminated and molded into recessed and projecting shapes with a height (h) of 3 to 100mm. Then at least, one of these unwoven clothes has a rupture ductility of 70% or higher at 100 deg.C or lower. In addition, the extremely fine unwoven cloth (b) and the fibrous sheets (a, c) are bonded together using thermal melting technique and an adhesive. Subsequently, the long life, efficient dust removal and high shape-retaining properties of the fiber are ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The molded filter of the present invention can be used as a filter for air cleaners, vacuum cleaners, and the like.

More specifically, the present invention is a molded filter that is molded into an uneven shape and has excellent filter life, dust removal performance, and shape retention.

(Prior Art) Conventional filters use resin-treated paper, nonwoven fabric, and the like. However, when molding such as pleating is performed to increase the surface area of the filter, problems such as smoke and irritating odors occur.

In addition, for the purpose of improving dust removal performance, there are filters using ultrafine fiber sheets. For example, JP-A-62-241
No. 519 discloses a filter in which an electret nonwoven fabric and a deodorizing material are laminated, but it is difficult to use as a flat surface molded product.

(What the invention seeks to solve) As a result of intensive study of the above-mentioned problems with filters, the present inventors have developed an ultra-fine nonwoven fabric that has excellent dust removal properties and a fiber sheet that can be deformed under heating at a relatively low temperature. They discovered that they can be laminated and molded, leading to the present invention.

(Means for Solving the Problems) That is, the present invention has: (1) an average fiber diameter of 0. 5-6,0μm, bulk density 0゜05
~0.50g/cii ultrafine nonwoven fabric, and one or both sides of the ultrafine nonwoven fabric have an average fiber diameter of 10 to 60μm and a bulk density of 0.0
5 to 0.50 g/d fiber sheets are laminated to a height of 3 to 0.5 g/d.
It is a molded filter formed into a concavo-convex shape of 100 mm, and furthermore, at least one of the fiber sheets has a 100 mm
It is characterized by having a breaking elongation of 70% or more at a temperature of 0"C, and also has the following characteristics: ■ The fiber sheet is made of aromatic polyester long fibers; ■ It is joined by heat fusion and adhesive. Also on the point,
It is also characterized by being processed to provide functionality.

Hereinafter, embodiments of the present invention will be shown and specifically explained.

FIG. 1 is a schematic cross-sectional view of the molded filter of the present invention. In FIG. 1, b is an ultrafine nonwoven fabric, and a and c are fiber sheets. Fiber sheets on both sides of the ultra-fine non-woven fabric a)
This is a molded filter in which C is laminated and molded into an uneven shape with a height h.

Considering the fiber sheet a in Fig. 1 as the air inlet side,
The role of the pre-filter material in collecting relatively large particles is large, and as a method to effectively perform the role of the pre-filter, a fiber sheet a with a coarse and dense structure is used.For example, a fiber sheet a with a bulk density of 0° A coarsely structured fiber sheet having a bulk density of 0.01 to 0.05 g/cj and a bulk density of 0.05 to 0.50 g/cj is preferably used.

On the other hand, the fiber seam (c) is located on the air outlet side, and it is important that the molded filter retains its shape without being deformed at the flow rate under use. Furthermore, unlike general plastic reinforcing materials, the fiber sheet C has the feature that its entire surface can be used as an effective area.

The molded filter shown in Figure 1 is made by layering FASC fiber sheets on both sides of an ultra-fine non-woven fabric, and laminating three sheets at a temperature of 60 to 1
It is heated to 50° C. and obtained using a pleating machine such as a folding method or an uneven roll method.

FIG. 2 is a schematic cross-sectional view of the molded filter of the present invention having a partial joint.

d in Fig. 2 shows a partial joint.The joining methods include partial thermocompression joining using an embossing roll, partial fusion joining using an ultrasonic welder, etc., and gravure roll, etc. There is adhesive bonding, which involves partially applying adhesive and bonding. At this time, the bonding area is preferably in the range of 1 to 15% in order not to impair filter performance.

FIG. 3 is a perspective view of the molded filter of the present invention.

Figure 3e shows the frame. The frame e can be selected from paper, wood, plastic, etc. depending on the purpose. At this time, the frame integrates the molded filter and frame to prevent air leakage.
It is made using adhesives, foam, cushioning materials, etc.

FIG. 4 is a schematic cross-sectional view of a molded filter having a two-layer structure made of fiber sheet A5 ultrafine nonwoven fabric.

In Fig. 4, when the air inlet side is in the direction a, the fiber sheet (a) plays a large role as a pre-filter, as in Fig. 1, but since the fiber sheet is one-sided, it does not provide shape retention. Its role as a reinforcing material is also important.

As mentioned above, the molded filter of the present invention includes a pre-filter 1 for the purpose of collecting relatively large particles, a fiber sheet that also serves as a reinforcing material to obtain shape retention, and a fiber sheet that has the ability to collect fine particles. This filter is made of a laminated sheet made of ultra-fine nonwoven fabric that has excellent properties, and is formed into an uneven shape to increase the filtration area and improve adhesion.

In the present invention, the ultrafine nonwoven fabric with an average fiber diameter of 0.5 to 6.0 μm is one or two types of polypropylene, polyethylene, polyester, polyamide, polyurethane, etc.
It can be obtained by a method of forming a sheet from a copolymer such as a copolymer such as a styrene-butadiene copolymer or a styrene-butadiene copolymer by a melt-blowing method, a direct spinning and paper-making method, a method of forming a sheet from split fibers, or the like.

The ultrafine nonwoven fabric is important for the dust removal properties of the molded filter of the present invention, and needs to have an average fiber diameter in the range of 0.5 to 660 μm. If the diameter is 0.5 μm or less, the strength of the single fiber is low and the handleability is poor. Further, if the thickness is 6.0 μm or more, the excellent dust removal properties aimed at by the present invention cannot be obtained.

Furthermore, it is important that the ultrafine nonwoven fabric of the present invention has low resistance to air flow, that is, low pressure loss. Therefore,
In order to reduce pressure loss, the bulk density should be set to 0.05 to 0.
．． It is necessary to set the range to 508/cm2. 0.
If it is less than 0.05 g/cj, the sheet state becomes difficult to handle, the fiber spacing becomes large, and the dust removal performance is poor. On the other hand, 0.5
If it is 0 g/cj or more, the fiber spacing becomes dense, pressure loss becomes large, and air resistance becomes large.

The fabric weight of the ultrafine nonwoven fabric of the present invention is not particularly limited, but is 10
~+00 g/po is preferable.

Further, the fibers are subjected to charging processing for the purpose of improving dust removal performance, and electret processing or the like can be performed.

The fiber sheet of the present invention includes polyethylene fibers, polypropylene fibers, polyester fibers, polyamide fibers, polyvinyl chloride fibers, polyethylene/polypropylene composite fibers, and heat-sealed fibers having an average fiber diameter in the range of 10 to 60 μm. It is a sheet-like material obtained by mixing or laminating one or more types of short fibers such as adhesive fibers and adhesive fibers, or long fibers.

The fibrous sheet material can be obtained by a known method such as a spunbond method or a needle punch method. The average fiber diameter must be in the range of 10 to 60 μm, and the bulk density must be 0.
．． A range of 0.05 to 0.50 g/cm2 is required. If the fiber diameter is less than 10 μm, clogging due to collection of particles is likely to occur, the role of a pre-filter is poor, and the shape retention of the molded product is also poor.

On the other hand, if the diameter is 60 μm or more, the particle collection performance is poor and the role of a pre-filter is poor. In addition, the bulk density is 0゜05g/c4
Below, the fiber spacing becomes large and particle collection performance is poor.
Furthermore, the shape retention of the molded product is also poor.

On the other hand, if it is 0.50 g/d or more, the fiber spacing becomes small, and clogging due to collection of particles tends to occur, resulting in a product with high pressure loss.

The laminated sheet-like product of the ultrafine nonwoven fabric and fiber sheet of the present invention is characterized in that it is formed into an uneven shape with a height of 3 to 100 degrees. If the height is less than 3 cm, the effect of expanding the filtration area, which is the objective of the uneven shape, will be small. If the height is more than 100 cm, the molded product will have poor shape retention and will be easily deformed by air flow.

The method of forming an uneven shape according to the present invention can be obtained by using the above-described pleating machine and a processing method using press molding such as a convex shape or an uneven shape. This molding processing condition has productivity,
From the viewpoint of workability, it is preferable that the process can be performed in an atmosphere at a temperature of 60 to 150°C.

Therefore, when the fiber sheet used in the present invention has a breaking elongation of 70% or more under heating at 100° C., it becomes easily deformed during molding, and the molding can be performed satisfactorily.

In particular, an aromatic polyester long fiber nonwoven fabric having a single filament elongation at break of 100% or more is preferably used as the fiber sheet of the present invention because it has excellent heat resistance, strength, moldability, shape retention, and the like.

Furthermore, the fiber sheet and laminated sheet-like product of the present invention are
Depending on the purpose, it can be treated with functionalities such as antibacterial agents, antifungal agents, and deodorants to prevent the growth of collected bacteria, mold, insects, etc.

(Examples) Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but these do not limit the scope of the present invention.

Note that the method for measuring the characteristic values used in the present invention is shown below.

■ Eye size (g/po): The weight of the sample 201 square is measured and converted to basis weight.

■ Bulk density (g/cd): Measure the basis weight and thickness with a dial gauge to find the weight per unit volume.

■Strength and elongation: Using a tensile tester, the grip length was 10 cm and the tensile speed was 20 C1.
Change the ambient temperature at a rate of 1/min and measure.

■ Dust removal performance: With Rion particle counter KC-01B,
Calculated from the difference in the number of particles between the blank and sample.

(Particle size: 0.3 μm or more, flow rate 0.54
! /m1n) ■Pressure loss Ni Pressure difference between blank and sample.

Example 1 Average fiber diameter obtained by one-way melt blowing: 1°7 μm,
Using electret-processed polypropylene ultrafine nonwoven fabric (b) with a bulk density of 0.16 g/cd and a basis weight of 30 g/rd, and a rectangular spinning nozzle with a pore diameter of 0.25 m and 1000 holes using the spunbond method, a discharge rate of 2000 g/min was used. and the intrinsic viscosity is 0.
75 polyethylene terephthalate at a melting temperature of 290℃
After spinning at a spinning speed of 1900 m/min, a long fiber web (single filament elongation at break 330%) was partially thermocompressed at a temperature of 75°C (compression area ratio 18%), and then heat treated in a felt calendar at a temperature of 100°C. , fiber sheets (a) and (C) were obtained.

The fiber sheet (a) has an average fiber diameter of 32 pm and a bulk density of 0°3.
The elongation at break is 550% at a temperature of 100° C. and a basis weight of 1 g/d. The fiber sheet (C) has an average fiber diameter of 33μ
m, bulk density 0.33g/cj, basis weight 100g/rrf,
The elongation at break at a temperature of 100°C is 490%.

As mentioned above, the fiber sheet and the ultrafine nonwoven fabric are (a), (b), and (c).
They were stacked one on top of the other in this order, and uneven molding was performed using a folding pleating machine under the conditions of temperature 80° C. and height h = 30 −.

The three laminated sheets could be integrally molded, and a molded filter with sufficient shape retention was obtained.

Next, using the framework shown in Figure 3, we measured the filter performance and found that the pressure loss was 1. A molded filter with excellent performance, with a 5W+Hz O1 dust removal rate of 98%, was obtained.

Comparative Example 1 Using a rectangular spinneret with a pore diameter of 0.25 m and 1000 holes using a spunbond method, the intrinsic viscosity was 0 at a discharge rate of 850 g/min.
．． 75 polyethylene terephthalate at a melting temperature of 290
The long iut web (single filament breaking elongation 65%) was spun at 5200 m/min at a spinning speed of 5200 m/min and partially thermocompressed at a temperature of 235°C (crimped area ratio 18%) to form fiber sheets (a) and (C). Obtained.

The fiber sheet (a) has an average fiber diameter of 13 μm and an X density of 0°1.
9g/cj, basis weight 50g/i, and elongation at break at 100°C 35%. Fiber sheath) (C) has an average fiber diameter of 14μ
m, a bulk density of 0.21 g/cj, a basis weight of 100 g/, and a breaking elongation of 30% at a temperature of 100°C.

Using the above fiber sheet and the ultrafine nonwoven fabric of Example 1, uneven molding was performed in the same manner as in Example I. As a result, moldability was poor, and a molded filter with the desired uneven shape could not be obtained.

Example 2 Polyethylene terephthalate with an intrinsic viscosity of 0.75 was spunbonded using a rectangular spinneret with a pore diameter of 0.25 mm and a number of holes of 1000 at a discharge rate of 2000 g/min at a melting temperature of 29 mm.
A long fiber web (single filament breaking elongation 450%) was spun at 0°C and spun at 1700 m/min, and was partially thermocompressed at a temperature of 70°C (crimped area ratio 18%), with an average fiber diameter of 32 μm and a bulk density of 0. ．．
A long fiber sheet with a weight of 23 g/d and a basis weight of 100 g/n was obtained.

These long fibers and a short fiber sheet consisting of a carded web of polyethylene-polypropylene composite fibers with a fiber length of 73 cm and an average fiber diameter of 20 μm were stacked together and needle punched using a number 40 needle and a punch density of 100 times/d. A fiber sheet with a coarse and dense structure consisting of a coarse density structure and a relatively high density structure was obtained. The obtained fiber sheet (a) has a bulk density of 0.1
3g/ag, the elongation at break at 100°C is 230%, and the basis weight is 200g/M.

The average fiber diameter is 1. A polyester ultrafine nonwoven fabric (b) of 8 μm, a bulk density of 0.30 g/cj, and a basis weight of 65 g/i is laminated with the above fiber sheet (a), the unit area of the convex portion is 0.6 2, and the crimped area ratio At 6%,
Heat fusion bonding was performed by partial thermocompression bonding using an embossing roll with a top and bottom temperature roll of 180°C and a linear pressure of 2°kg/cm.

Next, the obtained sheet was press-molded using a concavo-convex mold having a shape as shown in FIG. 4 at a height of 50 s+a and a temperature of 110''C to obtain a molded filter as shown in FIG. 4. The product has excellent shape retention properties against external forces and has a pressure loss of 5.
4. It is a molded filter with excellent HtO1 dust removal performance of 79%.

(Effect of the invention) The necessary conditions for a filter are: ■It must be able to collect fine particles and have excellent dust removal properties; ■It must be able to maintain its excellent dust removal performance for a long time (it must have an excellent filter life), and ■ It does not cause problems such as pollution and has excellent moldability.

The molded filter of the present invention is a filter that can satisfy the above conditions. Therefore, air purifiers, vacuum cleaners, automobiles,
It can be used in a wide range of fields, such as air filters for masks, filters for extracting ingredients from oil, tea, coffee, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a molded filter of the present invention having a three-layer structure. FIG. 2 is a schematic cross-sectional view of a molded filter of the present invention having a three-layer structure with partial joints. FIG. 3 is a perspective view of a molded filter of the present invention framed. FIG. 4 is a schematic cross-sectional view of a molded filter of the present invention having a two-layer structure. (a): Fiber sheet (b): Ultrafine nonwoven fabric (C); Fiber sheet (d): Joint part (e): Frame h: Height of unevenness (1 idiot) Figure 1

Claims (5)

[Claims] (1) Average fiber diameter is 0.5 to 6.0 μm, bulk density 0.05
~0.50g/cm^2 ultrafine nonwoven fabric, and one or both sides of the ultrafine nonwoven fabric have an average fiber diameter of 10~60μm and a bulk density of 0.50g/cm^2.
05~0.50g/cm^2 fiber sheets are laminated,
A molded filter characterized by being molded into an uneven shape with a height of 3 to 100 mm. (2) The molded filter according to claim (1), wherein at least one of the fiber sheets has a breaking elongation at 100° C. of 70% or more. (3) The molded filter according to any one of claims (1) and (2), wherein the fiber sheet is made of aromatic polyester long fibers. (4) The molded filter according to any one of claims (1) to (3), which is bonded by heat fusion and adhesive. (5) The molded filter according to any one of claims (1) to (4), which is processed to impart functionality.