DE1268036B - Filters for tobacco smoke or other gases - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

A 24 c

German class: 79 b -21/01

Number:
File number:
Registration date:
Display day:

P 12 68 036.3-23
April 10, 1963
May 9, 1968

The invention relates to filters for the treatment of tobacco smoke or other gases for the purpose of reducing their content of suspended matter and vapors of organic substances, especially on filters for cigarettes.

A popular form of cigarette filter is made from dry-spun cellulose acetate filaments and is made by gathering a large number of these threads into a strand which is then crimped, opened, plasticized, compressed to approximately the final desired diameter, wrapped in paper, cured and then cut into short pieces. The threads used have different titers and cross-sections depending on the wishes of the manufacturer with the filters cigarettes to be supplied. In general, threads with which a high ratio of surface area are used to gain weight is considered to be the most beneficial.

There are also known cigarette filters formed from fiber bundles in which the individual fibers have cavities and have a raw irregular surface. Such fibers can for example by Spinning of aerated regenerated cellulose. Here, however, is always the irregular one Surface connected with a high percentage of enclosed voids inside the fiber, whereby the single fiber and thus the fiber bundle is undesirable for practical processing Reduction in mechanical strength is maintained. The object of the invention is to these peculiarities of the Avoid known filter materials.

Because the nature of the surface of the threads has a big influence on the effectiveness of them Manufactured filters can have threads of a specific surface configuration by the invention and proposed a substantially round cross-section, which is more advantageous for filter manufacture are considered threads with a higher surface-to-weight ratio, e.g. threads with a lobed cross-section, however, have the surface of normal dry-spun filaments.

In the case of a filter for tobacco smoke or other gases made of cellulose ester threads, one of the cylinder shape have a different surface, the surface of the threads is bumpy according to the invention.

This humped surface that looks like an orange peel or fine-grained leather under the microscope is useful in gas filtration in several ways when the filaments are wrapped in a sheath need to be as with the currently used cigarette filters, increases the humpbacked Filters for tobacco smoke or other gases

Applicant:
5

Celanese Corporation of America,

New York, NY (V. St. A.)
Representative:

ίο Dr.-Ing. A. v. Kreisler, Dr.-Ing. K. Schönwald,
Dr.-Ing. Th. Meyer and Dr. JF Fues,
Patent Attorneys, 5000 Cologne 1, Deichmannhaus

Named as inventor:
John Einar Offerdahl,
John Joseph Osmar, Charlotte, N. C;
Thomas Waller George, Summit, NJ (V. St. A.)

Claimed priority:

V. St. v. America April 11, 1962 (188 300)

Surface the friction of the threads with each other, so that the filter compresses in stronger Dimensions resists as a filter made up of the same number of threads of the same titers, but without the pitted ones Surface are made. As a result, a desired degree of strength can be achieved with fewer threads or can be achieved with less binder.

In addition, the humped surface is great for a greater surface area to volume ratio responsible because it has smooth threads of the same general cross-sectional shape. That was demonstrated by comparing the speed with which the color on threads of smooth surface and pulls up on threads with a bumpy surface. Because the filtration often depends on the size of the adsorption Depending on the available surface area, this increased surface area has an increase in the amount of substance as a result, which is removed from the gas to be filtered per pass.

The improved filtration is generally achieved with cellulose acetate filaments with a humped surface. However, if the threads consist of cellulose triacetate, i. H. Cellulose acetate with an acetyl value of at least about 59 "Vo, preferably of at least about 61 percent by weight, calculated as bound Acetic acid, the filters have increased selectivity for weakly acidic substances such as phenols. Filter,

809 548/119

3 4

those made of cellulose triacetate with a humped upper but generally between 1.6 and 8, preferably

area are therefore particularly effective between 2.4 and 4.7.

sam in the treatment of gases that contain essential plasticizers are the usual, for example, amounts of weakly acidic substances, such as triethyl citrate, dimethoxyethyl phthalate, methyl, especially of tobacco combustion products, the phthalylethyl glycolate, monoacetin, diacetin and especially a significant amount of weakly acidic substances Triacetin. The applied plasticizers contain, but also of other gases, such. B. amount is generally 2 to 30 per weight chimney gases from stoves that are fired with fuels that are cent, preferably 4 to 15 percent by weight, based on rich in phenolic compounds, on the thread material, and finally with partial combustion products of io
polynuclear aromatic compounds. example

Threads with the desired humped surface

can be prepared by wet spinning cellulose triacetate - a 21% solution of cellulose triacetate with solutions in a coagulant that has a high swelling and acetyl value of 61%, calculated as a bonded effect on the threads. At 15 acetic acid, in a mixture of methyl chloride and a particularly suitable process, the counter- methanol (90:10) is through round nozzles from an earlier proposal, a solution 100 µm in diameter at 25 ° C in a methylene chloride of cellulose triacetate in methylene chloride or spun in a methanol mixture (50:50): The resulting solvent which contains methylene chloride as the main thread is spun into a coagulant at a draw ratio of 7: 1, 20 taken up to form a strand of 15,000 threads Methylene chloride and an aliphatic alcohol combined in four methanol baths and then in one with 1 to 3 carbon atoms in the molecule. The washed out of two water baths. The threads pressed with water are then stretched on their way through the networked cable with the aid of a stuffing box of coagulant. The methylene chloride is so crimped that it contains 3.1 crimps per centimeter in the coagulant in a concentration of more than 25 g (based on the stretched cable), and than 25 ^e / o. The concentration corresponds to one then dried. The filaments have a single titre value of 75.25 - (T ± 5), where T is the temperature of about 3 denier, an essentially round cross-section of the coagulant in ° C. For example, there can be a cut and a bumpy surface that resembles an orange peel under a 20% solution of cellulose triacetate in a microscope. The strand mixture of methylene chloride and methanol (90:10) 30 is then opened by being passed between three rollers at 35 ° C in a mixture of 40 parts of methylene pairs, in each of which one chloride and 60 parts of methanol are spun and with a roller corrugated and the other is smooth. This type of process is also applicable to other cellu-triacetin as a plasticizer. B. on acetone solutions of 35, with an endless strand of 25 mm Umsecondärem cellulose acetate. When these solutions are formed in fang, and water is spun into pieces 90 mm long, so much acetone is cut off. The filters harden when left lying around, if the mixture at the applied temperature holds the threads, due to the softening effect, a strong swelling effect on the cellulose maker in a known manner, veracetat, threads with a bumpy 40 will also stick. The filters are now ready for the surface included. Guided tour to the cigarette machine in which they are in short

The threads are usually cut through pieces of round openings and worked into the cigarettes

genes and have a round cross-section, ever.

but they can be used to achieve a further er- Instead of producing cigarette filters

increasing the surface-to-weight ratio 45, the dried and

also have other known shapes. crimped cords cut into staple fibers and closed

The threads described above can be processed nonwovens through the exhaust gases - preferably after known crimping - to systems in which aromatics are oxidized, Staple fibers can be cut and fed into a roving before releasing them into the atmosphere get out of the filter by plasticizing and at 5 °. In this way it is prevented that odor wraps can be produced. To produce substances escape while at the same time these substances However, cigarette filters will preferably be retained after the filter from which they pass worked the usual method in which the threads are separated by treatment with a solvent in the form of a strand of several thousand can be ended, with the filter at the same time rainless Threads are crimped, loosened, and red in the usual way.

plasticized and wrapped in paper, whereby the invention was particularly

Filters are obtained in which the threads are described in the hang with cellulose acetate, but can

essentially in the longitudinal direction from one end to the other, other lower fatty acid esters can also be used

others get lost. For cigarette filters more common, e.g. cellulose formate, cellulose propionate, cellulose

Size - e.g. B. with a circumference of about 25 mm - 60 lulose butyrate, cellulose acetate propionate, cellulose

the number of threads is generally 1,000 to butyrate acetate and the like, regardless of whether they

50,000, preferably 5,000 to 30,000, are essentially completely esterified in one Ge, d. H. less-

total titre from 25,000 to 160,000, based on the ger than about 0.29 free hydroxyl groups per anhy-

non-crimped cables. The single titer can contain up to droglucose units of the cellulose molecule,

or even more, however, depends on the 65 or whether they are only partially esterified,

common between 1 and 25 den, preferably between- If necessary, known additives such as Al-

between 2 and 15 den. The number of crimps per phacellulose flake, carbon powder and the like used

Centimeters can be up to 20 or more.

Claims (3)

Patent claims: 1. Filters for tobacco smoke or other gases, consisting of cellulose ester threads, one of the Have cylindrical shape deviating surface, characterized in that the surface the threads are bumpy. 2. Filter according to claim 1, characterized in that it consists of wet-spun in a known manner Threads. 3. Filter according to claims 1 and 2, characterized in that the form a strand bundled threads are connected to one another at their points of contact in a known manner. Documents considered: German Auslegeschrift No. 1028 926; Austrian Patent No. 191783; Swiss Patent No. 325 071; British Patent Nos. 749 340, 770 071.