RU2106790C1 - Cigarette filter and cigarette - Google Patents

Abstract

FIELD: cigarette industry. SUBSTANCE: cigarette filter has paper containing lyocellic filaments or made from such filaments. Cigarette is characterized in that it has such filter. EFFECT: increased filtering capacity and simplified construction. 8 cl, 4 tbl

Description

 The invention relates to paper filters for cigarettes.

 Fiber filters for cigarettes are well known. In one known embodiment, the housing of such a filter consists of a bundle of continuous fibers, usually cellulose acetate (acetate) fibers, running parallel to the longitudinal axis of the cigarette. In another known embodiment, the filter housing is made of folded or corrugated paper pressed into a cylinder. In order for the paper to be folded or corrugated, it is processed by making grooves. In such embodiments, a single filter element is provided, and may be called "single" filters. Another known type of construction is the so-called “double” filter, which consists of two filter elements, for example, a paper filter on the inside and a tow filter on the outside of the cigarette. Another known type of structure is the so-called “triple” filter, which includes three filter elements, for example a paper filter and a tow filter as a “double” structure, separated by an air gap or activated carbon filter [1].

 It is known that paper filters are generally more effective at removing tar from tobacco smoke than tow filters. Due to the tendency to produce cigarettes with a low tar content in tobacco smoke, a high removal efficiency is desired. The objective of the invention is to provide a filter mouthpiece of a cigarette with high resin removal efficiency. Another objective of the invention is the development of various designs of cigarettes with a reduced yield of resins.

 In accordance with the invention, there is provided a cigarette filter, characterized in that the filter housing includes paper that contains or substantially consists of lyocell fibers. In addition, the invention provides a cigarette that contains such a filter.

 Lyocell fibers are known materials, and their preparation is described, for example, in US Pat. No. 4,262,221. They are commercially available from Cortolds PLC (Tencel trademark). They are prepared by dissolving cellulose in a solvent, extruding the solution thus prepared through a die into a coagulation bath, which serves to precipitate cellulose, and washing the solvent off the fiber, a process called solvent spinning, and lyocell fibers can also be called cellulosic solvent molded pulps. Pulp is usually wood pulp. The solvent may be tertiary amine N-oxide, preferably an aqueous solution of tertiary amine N-oxide, in particular N-methylphospholine-N-oxide. If the solvent is tertiary N-oxide amine, the preferred coagulation bath is an aqueous bath This solution molding method must be distinguished from other known methods for producing cellulosic fibers, which are based on the preparation and decomposition of chemical aqueous pulp, for example from a viscose process. Lyocell fibers are readily biodegradable. The lyocell fiber may contain a matting pigment, in particular titanium dioxide, and may be chemically bleached.

 The cigarette filter according to the invention has a high filtering ability in comparison with the known paper filters.

Paper for use as a cigarette filter according to the invention can be manufactured using conventional papermaking techniques and equipment. The density of the paper used in the filter according to the invention, as a rule, can be identical to the density of ordinary paper used in the composition of known paper filters; it usually ranges from 15 to 150 g / m ² , preferably from 20 to 80 g / m ² . Such paper may consist essentially of lyocell fibers or, in addition to lyocell fibers, may contain other types of fibers, for example plant fibers, in particular wood pulp and / or acetate fibers. It has been found that paper can include up to about 50 wt.% Wood pulp without a noticeable decrease in tar removal efficiency, although naturally, at a higher content than that indicated, this efficiency shows an increasing tendency to the efficiency of plain paper from wood pulp. You can make paper, which includes at least 25 wt.% Lyocell fibers, partially mixed with wood pulp fibers. Paper that contains approximately 50 wt. % lyocell fibers and wood pulp fibers may be even more preferred. It was also found that the inclusion of a certain proportion of wood pulp in such a mixture can contribute to the paper forming process, making it possible to improve the quality of the paper.

 The tensile strength in the transverse direction (PN) of the paper used in the filter according to the invention should be selected in order to ensure the exact degree of execution of the grooves, and, therefore, its folding or corrugation. A low PN tensile strength may mean that the groove turned out to be excessively large, resulting in a too high pressure drop in the filter, while a high PN tensile strength may mean that the groove is too small, resulting in an unsatisfactory final appearance of the filter .

 The preferred lyocell fiber in the filter of the invention should be fibrillated. Lyocell fibers can be fibrillated, subjecting them to mechanical failure in the wet state, as, for example, during the papermaking process. The result of fibrillation is the separation of thin hairs ("fibrils") from the body of the fiber, so that individual fibers acquire a "hairy" external pitchfork. Fibrillated lyocell fibers have an increased surface area compared to unfibrillated fibers, and this is believed to be an advantage for efficient filtration.

 The paper may consist of a mixture of highly fibrillated lyocell fibers with other types of fibers, such as plant fibers such as wood pulp and / or acetate fibers. Highly fibrillated lyocell fibers can be obtained under harsh cleaning conditions. The drying of the pulp of the paper manufacturing process containing such fibers is very slow, as a result of which it is usually unsuitable for use in the industrial production of paper for cigarette filters. Such a pulp can be mixed with a pulp containing other types of fiber, including a pulp containing low fibrillated lyocell fibers, and used in the manufacture of paper. This mixture of highly fibrillated lyocell fibrous cellulosic pulp and pulp containing other types of fibers can be selected to balance the properties of the paper and filter and the cost of the paper manufacturing process. You can choose a mixture of highly fibrillated lyocell fibers with acetate fibers, which provides good dehumidification in the manufacture of paper, good paper strength, improved filtering efficiency compared to that achieved with acetate fibers only, water washability (i.e. water dispersibility) of cigarette filters, and faster biodegradability than filters made only from acetate fibers.

 The filter according to the invention can be a single, double or triple filter. Double and triple filters may be preferred, including an acetate tow filter on the outside of the cigarette and a lyocell filter on the inside of the cigarette. Such filters exhibit good stain resistance on the outside.

 Filter elements and filters in accordance with the invention can be used in cigarettes with filters that have or do not have ventilation openings, with tobacco packing of a wide range of varieties. By way of example only, such a tobacco packing may have one, several, or all of the following properties.

 Nicotine / tar yield • 10 = 0.05-1.0.

The density of the tobacco filling is 100-260 kg / m ³ .

 Tightening resistance (measured in the closed state) is 35-70 mm of aircraft.

 Breathability of cigarette paper = 10-150 units. Coresta.

 Also, by way of example only, a filter cigarette in accordance with the invention, which contains a tobacco pack as described above, or a pack with other properties, may exhibit one, several, or all of the following properties.

 Nicotine / tar yield • 10 = 0.05-1.5.

 Resin yield = <1 to 10 mg.

Tightening resistance (measured in closed state) = 30-150 mm W6
Ventilation in the filter = 0-80%.

 Puff rating: ≥5.

 The above parameters are measured according to standard procedures and expressed in standard units. Sun stands for water column.

 In addition, the tobacco mixture may contain significant amounts of loose tobacco leaves and medium veins.

 Filters according to the invention, for example, containing lyocell fibers alone or in a mixture with wood pulp, have significantly more advanced properties to retain resins in a wide range of pressure drops compared to previously known cellulose acetate and paper (100% of wood pulp) filters. The filters of the invention can be used in the manufacture of cigarettes with a resin yield of 6 mg or less, possibly only 1 mg or less. Such a low yield of resin can be achieved with a significantly lower degree of ventilation than is necessary in the case of previously known filters. Given consumer acceptability, a high degree of ventilation is usually undesirable. In addition, such a low resin yield can be achieved with acceptable puff resistance, which is an additional contribution to increasing consumer acceptance relative to that achieved with previously known cigarettes. In accordance with the invention, filters are made which, with the same degree of ventilation, are characterized by improved filtering efficiency and low pressure drop compared to previously known filters.

 Examples of cigarettes made in accordance with the invention encompass cigarettes, the construction of which has the following properties: yield of tar gums (yield) - 25 mg; pressure drop - 50 mm; permeability of cigarette paper - 60 units. Coresta; the required resin yield (yield) is 4 mg. The degree of retention and ventilation that is necessary to achieve such a resin yield can be calculated by the equation. Final resin yield = tobacco packing yield • (100-R) / 100 • (100-V) / 100, where R is the filter retention rate in% and V is the% ventilation rate. If the degree of ventilation is 0%, then the required degree of retention by the filter is 84%. It is believed that such a high degree of retention in a conventional acceptable filter cigarette is unattainable. Manufactured cigarettes equipped with 20 mm filters in accordance with the invention, which exhibit such a degree of retention at an acceptable pressure drop in the cigarette (approximately 144 mm BC).

 A cigarette of one of the previously known types may have a single paper filter with a tar retention rate of 66% and a pressure drop of 88 mm BC. To achieve the required 4 mg resin yield, ventilation should be 53% in combination with a pressure drop in the cigarette of approximately 95 mm.

 A previously known cigarette of a different type may have a single acetate filter (tow, 1.5 denier), the resin retention rate of which is 55%, and the pressure drop is 89 mm BC. To achieve the required 4 mg resin yield, ventilation should be 64% combined with an undesirably low pressure drop in the cigarette of approximately 87 mm.

 A cigarette according to the invention may have a lyocell paper filter with a resin retention rate of 77% and a pressure drop of 84 mm. To achieve the required 4 mg resin yield, ventilation should be only 30% in combination with a pressure drop in the cigarette of approximately 110 mm.

 It is easy to make cigarettes with even lower resin yields. A designer of cigarette designs can easily imagine cigarette designs other than those given above by way of example. An advantage of the invention is that low tar cigarettes can be made with a low degree of ventilation. This allows a reduced amount of sidestream smoke.

 In another embodiment, in accordance with the invention, it is possible to construct a filter which is lighter in weight than filters of known types that are characterized by the same filtering efficiency. This makes it possible to construct lighter cigarettes. Moreover, the tightening resistance of these filters in accordance with the invention may be lower than that of such previously known filters.

 It was found that during the smoking of cigarettes, the filters of the invention absorb moisture from smoke. As a result of this, the filter swells and the pressure drop across the filter increases. It is believed that in the process of smoking a cigarette this may impart some progressive filtering properties. Moreover, it is believed that this swelling may provide a particular advantage in the ability to manufacture cigarettes that exhibit a relative constancy of pressure drop from one puff to another.

 Example. Using 6 mm frosted 1.7 decitex lyocell fiber manufactured by Cortolds PLC (Tencel trademark), paper samples were prepared.

 The dispersion of the pulp was directed into the breaker at a mass density of approximately 1.5%. This mass was then fed into the pulp tank, where the mass was carefully circulated with a stirrer and diluted to the desired density. From the pulp tank, the mass was passed at room temperature through a conical refiner with a flow rate of 350-400 l / min. The shaft was separated from the housing with the formation of a gap of 15 mm, which ensured not so much fiber cutting as fibrillation. The course of grinding was periodically monitored by measuring the degree of grinding (according to the Shopper-Riegler instrument). After grinding, the mass was further diluted, as a rule, by adding water in an amount of about half the volume of the mass and pumped into the pulp tank of the paper machine. From the pulp tank, the pulp was pumped into a dilution tank, and then passed through a stream atomizer, which provided uniform dispersion of the fibers in the headbox (where the tow was formed from paper). In two vacuum drawer systems, water was removed, then the paper was run through two presses (one on each side), a drum dryer and a calender and collected on a drum. In the table. 1 provides information on paper manufacturing conditions. The properties of the samples are presented in table. 2.

 In the table. 2 PH means longitudinal direction. The rise is the result of measuring the capillary rise of water.

Rods for filter mouthpieces were made from sample A cut into strips 300 mm wide and wrapped in 27 g / m ² paper (made from wood pulp). The nominal sizes of the rods for the mouthpieces were 108 mm in length and 24.6 mm in circumference. These rods were cut for testing into 20 mm mouthpieces. Received the results, which are presented in table. 3.

 Rigidity is a measure of shape retention when exposed to lateral forces, with higher values indicating higher compressive strength.

 It would be expected that the retention rate of the resins with a conventional paper filter of the same size and pressure drop is approximately 74%.

Paper samples were cut into strips with a width of 250 mm, the rods were made at the maximum degree of corrugation and wrapped in paper 27 g / m ² . The nominal dimensions of the rods for the mouthpiece were 108 x 24.6 mm. These rods were cut for testing into 20 mm mouthpieces. Received the results, which are presented in table. 4.

 These filters showed significantly higher resin retention rates than both cellulose acetate tow filters and conventional semi-creped tissue paper filters.

Claims (8)

 1. Cigarette filter, characterized in that the filter housing includes paper that contains essentially or consists of lyocell fibers.  2. The filter according to claim 1, characterized in that lyocell fibers are obtained by carrying out a process comprising the step of extruding a solution of cellulose in a tertiary amine N-oxide into an aqueous coagulation bath. 3. The filter according to claim 1 or 2, characterized in that the paper density is from 15 to 150 g / m ² . 4. The filter according to claim 3, characterized in that the paper density is in the range of 20 - 80 g / m ² .  5. The filter according to any one of claims 1 to 4, characterized in that the paper consists of a mixture of lyocell fibers with plant fibers and / or cellulose acetate fibers.  6. The filter according to claim 5, characterized in that the paper consists of a mixture of lyocell fibers with wood pulp and contains up to about 50 wt.% Wood pulp.  7. The filter according to any one of claims 1 to 6, characterized in that the lyocell fibers fibrillate.  8. A cigarette, characterized in that it includes a filter according to any one of claims 1 to 7.

Images