DE2253925A1 - FILTER MATERIAL - Google Patents

Description

Dr. F. Zumstein Sr. - Dr. E. Assmann

Dr. R. Koenlgsberger - Dlpl.-Phys. R. Holzbauer - Dr. F *. Zumstein Jun.

PATENT LAWYERS

TELEPHONE: COLLECTIVE NO. 225341

TELEX 529979

TELEGRAMS: ZUMPAT CHECK ACCOUNT: MUNICH 91139

BANK ACCOUNT: BANK H. HOUSES

8 MUNICH 2.

BRÄUHAUSSTRASSE 4 / III

xc / n Case TX 5081

DUNLOP LIMITED, London, S.W.l / Great Britain

Filter material

The invention relates to a filter material, in particular a material which is suitable for air filters.

In one type of conventional air filter, the filter medium consists of a glass fiber fabric. The glass fibers have a number of properties that make them suitable as a filter medium, such as non-flammability, - the light weight Accessibility and the relative cheapness. However, glass fibers are very brittle and therefore sensitive to improper use Treatment during transport, versus handling during installation and use in High speed air filter systems. Great care is therefore required to prevent the fibers from breaking Destruction of the structure and a disintegration of the fibers into small particles is avoided. Small fibers and particles of glass can flow in high-speed air currents during installation and subsequent use be harmful.

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It has now been found that certain synthetic fibers
Technical advantages of glass, ie an efficiency of the same order of magnitude, have and at the same time light
can be installed and used without the risk of destroying the structure of the fiber medium
or fiber breakage occurs.

According to one embodiment of the invention, a filter material which is suitable as a filter medium for air filters comprises a non-woven fiber fleece whose weight-based main component consists of halogen-containing fibers,
the halogen-containing fibers being characterized in that they

1.) a toughness (tensile strength) of at least 2.5 g / Denier,

2.) an elongation at break of at least 30% and

3.) at 110 ⁰ C a shrinkage of not more than 5%

exhibit.

The halogen-containing fibers used according to the invention are fibers which consist of any long-chain synthetic polymer which is composed of at least 85% by weight of vinyl halide units. The halogen-containing fibers are preferably composed of polyvinyl chloride, the
Has 85% by weight of vinyl chloride units. A particularly suitable polyvinyl chloride is syndiotactic polyvinyl chloride. Other halogen-containing fibers such as polyvinyl bromide can also be used provided they have the required physical properties.

The toughness is preferably that of the halogen-containing
Fibers at least 2.7 g / denier, more preferably at least 2.9 g / denier. The determinations of toughness and elongation
When the halogen-containing fibers break, they take place at a temperature of 21 C and a relative humidity of 65%.

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Although the shrinkage of the halogen-containing fibers is no longer should be than 5% at 110 ° C, it is preferred that the Fibers show practically no shrinkage at 110 ° C.

As already stated above, the main component of the fiber fleece consists of halogen-containing fibers. So others can Fibers are mixed with the halogen-containing fibers, which can serve to the filter medium. Additional advantageous To give properties. Fibers of this type include polyester and modacrylonitrile fibers.

However, the fleece preferably contains considerably more than 50% by weight of halogen-containing fibers, the preferred minimum amount being 70% by weight, advantageously 80% by weight and most preferably "x 90% by weight.

The fibers are advantageously in a mechanical or chemically induced curl condition and have either a zigzag or a spiral curl. With advantage the fibers are opened in order to give the fleece an optimal volume »The opening of the fibers can suitably by carding and / or cross-lapping or preferably aerodynamically using a random webber device take place.

The titer of the fibers can vary over a wide range depending on the requirements of the filter but advantageously within a range of 10 ' up to 60 denier. It is not necessary to have all fibers have the same denier, and thus, for example, a mixture of fibers of 35 denier and 50 denier can be used.

Similarly, the fiber length can vary with the type of used Processing of the fiber device used will vary. It is not necessary that all fibers be the same length and for the random webber device e.g.

19/087 /.

BATH ORIGINAL

Mixtures of fibers with lengths of 70 mm and 90 mm can be used. *

The fibers forming the filter medium are preferably connected to one another with the aid of a resin binder the opened fiber structure is retained and a decrease in thickness and a deterioration in the technical operating properties is avoided during both transport and handling during installation and this prevents the filter medium from being destroyed when air flows through the fleece at high speed. leads to be. The fleece can be impregnated or sprayed or a combination of such process measures treated with the resin. Preferably, the web is uniformly saturated, including a large number of Resins can be used. The criteria according to which suitable resins are selected are essentially: that the crosslinking of the polymer (s) used occurs at a temperature which is lower lies as the shrinkage point of the heat-sensitive fiber that makes up the filter material. Some examples of suitable Resins are styrene / butadiene copolymers, styrene / Butadiene / acrylonitrile terpolymers, urea / formaldehyde resins and melamine / formaldehyde resins. However, the preferred resin is an acrylonitrile resin.

For some uses, in order for the product to have the required flame resistance, it is necessary to have a to add a suitable flame-retardant additive to the resin » Antimony trioxide is an additive that is suitable for this purpose, although it does not make other known agents of this type are excluded from the use according to the invention.

For some other end uses, the filter media is covered preferably with other materials, such as oils, in order to improve the filter efficiency. For this purpose Irus oil (available from Shell) is a particularly suitable additive that can be used during manufacture or after

30 9 8 19 / 087A

can add to the cutting of the medium into the desired dimensions.

The final thickness of the filter medium largely depends on the conditions prevailing during the application, e.g. the air throughput, the size of the dust and the pressure. Typically the thickness is 1 to 3 inches (2.54 cm to 7.62 cm).

The non-woven fiber fleece according to the invention is available in both disposable air filters as well as permanently installed filters as a filter medium.

The manufacture of filters using the inventive Materials will be further explained in the following examples.

example 1

A bale of chlorine-containing fiber, which was made of syndiotactic polyvinyl chloride and was flame-retardant, had a fiber tenacity of 2.8 g / denier and an elongation at break of 40 % , was opened and brought into contact with the room atmosphere overnight.

A certain amount of fiber was then fed into the hopper of a Random Webber device so that it was at the outlet apron a fleece with a weight of 430 g / m 2 and a thickness of 8.5 cm emerged. The fleece was with an aqueous Acrylonitrile resin emulsion containing dye and antimony trioxide, saturated and passed through a heat chamber and dried. The total amount of resin and additives added was 330 g / m 2. The resin treated fleece was then in cured in a second heating zone at a temperature of 94 ° C for 10 minutes. The obtained flame-retardant filter medium had a final thickness of 5.5 cm.

The filter media showed when placed in a cubic air filter [50.80 50.80 50.80 cm (20 20 20 inches)] below

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Application of the test specification BS 2831 up to a desired one Pressure drop of 0.5 inches water gauge using # 2 dust (Aloxite 50) at 56.6 m / min. (2000 c.f.m.) examined an average retention efficiency of 96.5% and a dust holding capacity of 6,250 g. It no signs of broken fibers could be seen.

Example 2

Example 1 was repeated using bales of 7.62 cm (3 inches) long staple fibers (24 denier "Dynel" modacrylonitrile fibers) with 8 to 9 crimps per 2.54 cm crimped fiber and 10.16 cm (4 inches) staple fiber (15 denier "Vestan" Polyester fiber) at 7 to 8 crimps per inch of crimped fiber.

After conditioning, a mixture of 85% of the Modacrylonitrilf asern and 15% of the polyester fibers into the random webber facility introduced, a fleece having a basis weight of 410 g / m 2 and a thickness of 9 cm was obtained. To the treatment with the resin emulsion (the total amount of resin plus additives 3 being 30 g / m 2) curing occurred during 12 minutes at 80 ° C. The thickness of the final product was 5.0 cm.

When tested according to the procedure described in Example 1, the filter medium demonstrated retention efficiency of 96% and a dust capacity of 6000 g.

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Claims (15)

- 7 claims. "P Filter material which is suitable as a filter medium for air filters, characterized in that it comprises a fiber fleece, the main component of which, based on weight, consists of halogen-containing fibers, which are characterized in that they 1.) a tenacity of at least 2.5 g / denier, 2.) an elongation at break of at least 30% and 3.) at 110 ⁰ C a shrinkage of not more than 5% exhibit. 2.) Filter material according to claim 1, characterized in that that the tenacity of the halogen-containing fibers is at least 2.7 g / denier. 3.) Filter material according to claim 1, characterized in that the halogen-containing fibers have a toughness of be at least 2.9 g / denier. 4.) Filter material according to claim 1, characterized in that the halogen-containing fibers at 110 ⁰ C show essentially no shrinkage. 5.) Filter material according to one of the preceding claims, characterized in that the halogen-containing fibers are formed from polyvinyl chloride, which is 85% by weight is built up from vinyl chloride units. 6.) Filter material according to claim 5, characterized in that the polyvinyl chloride is syndiotactic polyvinyl chloride is. ' 7.) Filter material according to "one of the preceding claims, characterized in that the fleece is at least 70% by weight contains halogen-containing fibers, 309819/0874 8.) Filter material according to one of the preceding claims, characterized in that the fleece is at least 80% by weight contains halogen-containing fibers. 9.) Filter material according to one of the preceding claims, characterized in that the fleece is at least 90% by weight contains halogen-containing fibers. 10.) Filter material according to one of the preceding claims, characterized in that the fibers have a zigzag or spiral crimp. 11.) Filter material according to one of the preceding claims, characterized in that the fibers are open. 12.) Filter material according to one of the preceding claims, characterized in that the fibers have a titer of. between 10 to 60 denier. 13.) Filter material according to one of the preceding claims, characterized in that the forming the fleece Fibers are connected to each other with a resin. 14.) Filter material according to claim 13, characterized in that the resin is a styrene / ßutadiene resin, a styrene / Butadiene / acrylonitrile resin, a urea / formaldehyde resin or a melamine / formaldehyde resin is used. 15.) Filter material according to one of the preceding claims, characterized in that it has a thickness of 2.54 cm to 7.62 cm (1 to 3 inches). 3098 1 9/0874