JPH11137930A - Heat-resistant filter material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily form a nonwoven fiber aggregate and to obtain a heat- resistant filter material having excellent heat resistance and chemical stability by constituting the nonwoven fiber aggregate of a mixture of a polytetrafluoroethylene fiber and an aromatic polyimide fiber. SOLUTION: This heat-resistant filter material consists of a base cloth 1 comprising a woven fabric produced by plain weaving of glass fiber multifilament, and a pair of nonwoven fiber aggregates 2, 3 laminated on both surfaces of the base cloth 1 entangled and integrated by needling. The glass fiber multifilament which constitute the base cloth 1 are coated with a polytetrafluoroethylene resin so as to suppress damages during needling. The nonwoven fiber aggregates 2, 3 consist of a mixture of polytetrafluoroethylene fiber and an aromatic polyimide fiber. The compounding proportions of the polytetrafluoroethylene fiber and the aromatic polyimide fiber are preferably controlled to about 60 to 90 wt.% and about 5 to 40 wt.%, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-resistant filter material for collecting dust in a high-temperature gas.

[0002]

2. Description of the Related Art In a bag filter device for collecting and separating dust from a high-temperature exhaust gas discharged from a refuse incinerator or the like, a filter material made of fibers having heat resistance capable of withstanding the high temperature of the exhaust gas is used. However, the heat-resistant filter material is generally made of a woven fabric made of glass fiber or polytetrafluoroethylene (PTFE) fiber.

[0003] On the other hand, in order to increase the collection rate of the fine dust and at the same time secure the required mechanical strength, a fine cloth capable of collecting the fine dust on the base cloth made of woven fabric is used. While adopting a multilayer structure in which woven fiber aggregates are laminated,
A filter material in which this nonwoven fiber aggregate is formed by mixing fibers of various materials with glass fiber or polytetrafluoroethylene fiber has been proposed and put into practical use (Japanese Patent Laid-Open No. 2-135).
No. 106, JP-A-5-71055).

[0004]

However, since glass fibers are brittle and easily broken, handling during the production of non-woven fiber aggregates is troublesome, and since they are poor in alkali resistance, a dust film is formed. Applying to the nonwoven fiber layer on the front side may impair the chemical stability and is not desirable.

[0005] On the other hand, polytetrafluoroethylene fibers have both excellent chemical stability and heat resistance, and are most suitable as a material for heat resistant filters. There is a problem that it is difficult to form a nonwoven fiber aggregate by entanglement.In this regard, the filter material of the conventional configuration has not been sufficiently solved, and furthermore, compared with the polytetrafluoroethylene fiber alone. However, there is a problem that heat resistance is greatly reduced.

The present invention solves the above-mentioned problems of the prior art and provides a heat-resistant filter material which is easy to form a nonwoven fiber aggregate and has excellent heat resistance and chemical stability. It was devised for the purpose.

[0007]

In order to achieve the above object, in the present invention, a heat-resistant filter material is formed by laminating and integrating a nonwoven fiber aggregate on a woven base cloth. This nonwoven fiber aggregate was made of a mixture of polytetrafluoroethylene fibers and aromatic polyimide fibers. According to this, it is possible to easily obtain a nonwoven fiber aggregate that is difficult to produce with only polytetrafluoroethylene fibers.

That is, in the case of using only polytetrafluoroethylene fibers having a small surface friction coefficient, in the process of producing a nonwoven fiber aggregate by using a card, a draft generated when the fibers are transferred from a doffer to a conveyor in the next process causes an effect between the fibers. The nonwoven fiber aggregate breaks due to slippage. On the other hand, the aromatic polyimide fiber has an irregular cross-sectional shape and has a large surface friction coefficient as compared with the polytetrafluoroethylene fiber. By doing so, slippage between the fibers is suppressed, and a desired nonwoven fiber aggregate can be obtained without being broken in the process of manufacturing the nonwoven fiber aggregate using the card. In particular, if entanglement treatment such as needling is sufficiently performed using crimped staple fibers for both fibers, an extremely dense filter material in which the fibers are strongly entangled can be obtained. In addition, when the base fabric and the nonwoven fiber aggregate are entangled and integrated, the polyimide fibers are entangled with the fibers forming the base fabric, and the bonding between the base fabric and the nonwoven fiber aggregate is strengthened.

In addition, since the aromatic polyimide fiber has heat resistance close to that of polytetrafluoroethylene fiber, even if it is mixed with polytetrafluoroethylene fiber, the heat resistance does not need to be reduced so much. In addition, since the cost is lower than that of the polytetrafluoroethylene fiber, the production cost can be reduced. As described above, by mixing the aromatic polyimide fiber with the polytetrafluoroethylene fiber, it is possible to solve the above-described problem without impairing the performance as a heat-resistant filter material and to reduce the cost at the same time. Become.

[0010] In addition, it is preferable that the base fabric made of the woven fabric be made of glass fiber coated with a polytetrafluoroethylene resin. According to this, since the woven fabric of glass fiber has high tensile strength and is hardly stretched, a filter material having high strength and excellent dimensional stability can be obtained. Moreover,
Since glass fibers are relatively inexpensive, manufacturing costs can be reduced.

Further, by coating the glass fiber with a polytetrafluoroethylene resin, it is possible to prevent the glass fiber from being damaged at the time of needling. Integration can be performed easily. Furthermore, the fine fibers generated by the damage of the glass fibers are not scattered in the air or adhere to hands or clothes when they come into contact with the product, and the problem of the sanitary environment is also solved. Moreover, this coating can improve the alkali resistance, which is a weak point of glass fibers. In addition, in order to integrate the base fabric and the nonwoven fiber aggregate, a spunlace method of entanglement of the fibers by a high-speed water flow may be adopted.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a heat-resistant filter material constructed according to the present invention. The heat-resistant filter material includes a base fabric 1 made of a woven fabric formed by plain weaving a glass fiber multifilament yarn, and a pair of nonwoven fiber aggregates 2.3 laminated on both front and back surfaces of the base fabric 1. Are entangled and integrated by needling.

The glass fibers forming the base fabric 1 are coated with a polytetrafluoroethylene resin in order to suppress damage during needling. The nonwoven fiber aggregates 2 and 3 are made of a mixture of polytetrafluoroethylene fibers and aromatic polyimide fibers.

The nonwoven fiber aggregates 2 and 3 are obtained by mixing a polytetrafluoroethylene fiber and an aromatic polyimide fiber at a predetermined mixing ratio with a cotton blender and passing the mixture through a card. Both fibers are made of crimped staple fiber and have a fineness of 1
It is preferable that the denier is about 3 denier and the aromatic polyimide fiber is about 2 denier.

The mixing ratio of the polytetrafluoroethylene fiber and the aromatic polyimide fiber is appropriately selected according to the properties of the gas to be treated. 5 to 40% of aromatic polyimide fiber, preferably 70 to 80% of polytetrafluoroethylene fiber, and 20 to 80% of aromatic polyimide fiber.
A good value is 30%. When the blending ratio of the aromatic polyimide fiber is suppressed to such a degree, it becomes possible to withstand a high temperature exceeding 200 ° C. in ordinary use, and it is possible to obtain heat resistance close to that of a polytetrafluoroethylene fiber alone.

The mixing ratio of the two fibers may be different between the front and back fiber aggregates 2 and 3. For example, when the ratio of the polytetrafluoroethylene fiber is increased in the fiber assembly 2 on the front side where the dust film is formed facing the flow direction of the gas, and reduced in the fiber assembly 3 on the back side, the polytetrafluoroethylene fiber The high fiber stability of the fiber assembly 2 on the front side enhances the high chemical stability and the property of facilitating the removal of dust.

[0018]

EXAMPLE A heat-resistant filter material constructed as described above was actually manufactured. The base fabric 1 is made of multifilament glass fiber yarn having a fiber diameter of 6 μm, and has a basis weight of 340 g / m 2.
^The one woven so as to be ² was used. The nonwoven fiber aggregates 2 and 3 used were a mixture of 75% polytetrafluoroethylene fiber having a fineness of 3 denier and 25% aromatic polyimide fiber having a fineness of 2 denier.

In a manufacturing apparatus (not shown) in which a card and a needle machine are interlocked, first, 230 g / m ^{2 of} the nonwoven fiber aggregates 2 and 3 are arranged in the order of the back and the front, respectively. 13
mm, the base cloth 1 under the needle conditions of 300,000 pieces / m ²
In order to improve the entanglement between the non-woven fiber aggregates 2.3 and between the non-woven fiber aggregates 2.3 and the base fabric 1 and at the same time prepare the surface, a total of 2.8 million from the back and front / M
^Performed a blank shot of ² .

In the finishing step, the feed rate is 20 m / min.
At 300 ℃, surface speed 2.5m /
Heat treatment was performed with a calender roller of min. As a result, a filter material having a basis weight of 800 g / m ² and a thickness of 1.6 mm was obtained.

The air permeability of this filter material is 15 cc / sec.
c / cm ² . The strong elongation is 160k in the vertical direction.
g / 5 cm, 180 kg / 5 cm in the transverse direction, and the burst strength was 43 kg.

Further, a durability test was carried out in a garbage incinerator in an atmosphere corresponding to a sulfur oxide concentration of 100 ppm and a temperature of 230 to 260 ° C. As a result, no remarkable deterioration was recognized, and excellent heat resistance and acid resistance were obtained. It was confirmed that.

[0023]

As described above, according to the present invention, an aromatic polyimide fiber having an irregular cross-sectional shape and having a larger surface friction coefficient than a polytetrafluoroethylene fiber is converted into a polytetrafluoroethylene fiber. Due to the mixing, the nonwoven fiber aggregate can be easily formed, and further,
By performing the entanglement process such as needling sufficiently, a strong and dense filter material can be obtained. This can have a great effect in improving the initial leakage at the start of the filter device. Moreover, the aromatic polyimide fiber has heat resistance close to that of polytetrafluoroethylene fiber, and is inexpensive compared to polytetrafluoroethylene fiber, so it has excellent heat resistance close to that of polytetrafluoroethylene fiber alone. The filter material can be manufactured at low cost. Further, by using glass fibers for the base cloth, it is possible to achieve high mechanical strength and at the same time further reduce costs.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a heat-resistant filter configured according to the present invention.

[Explanation of Signs] 1 Base cloth 2.3 Fiber aggregate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B32B 27/30 B32B 27/30 D 27/34 27/34 D06M 15/256 D06M 15/256 // D04H 1/42 D04H 1 / 42 W

Claims (2)

[Claims] 1. A heat-resistant filter material obtained by laminating and integrating a nonwoven fiber aggregate on a base cloth made of a woven fabric, wherein the nonwoven fiber aggregate comprises polytetrafluoroethylene fibers and aromatic polyimide fibers. A heat-resistant filter material comprising a mixture of: 2. The heat-resistant filter material according to claim 1, wherein the base cloth is made of glass fiber coated with a polytetrafluoroethylene resin.