Filter Paper for Cigarette Filters and Filter Comprising It

Abstract

The object of the invention is a filter paper characterized in that it includes between 70% and 100% by weight of cellulose fibers, wherein between 50% and 75% by weight of the fibers are long fibers, understanding by this fibers that have an average length greater than 2 mm, and between 25% and 50% by weight of the fibers are short fibers, understanding by this fibers that have an average length of less than 2 mm; between 0.1% and 5.0% by weight of sodium carboxymethyl cellulose; and wherein the weight of the filter paper per unit area is between 25 and 55 g/m.sup.2, measured according to UNE-EN ISO 536:2013 standard; the density thereof varies between 0.100 and 0.500 g/cm.sup.3, measured according to UNE-EN ISO 534:2012 standard in a single sheet; and the porosity of the filter paper is between 1500 and 8500 ml/min.Math.cm.sup.2.Math.kPa, measured according to UNE-EN ISO 2965:2019 standard. The paper filter including said filter paper is also an object of the invention.

Claims

1. A filter paper comprising: a) between 70% and 100% by weight of cellulose fibers, wherein between 50% and 75% by weight of the fibers are long fibers, understanding by long fibers those having an average length greater than 2 mm, and wherein between 25% and 50% by weight of the fibers are short fibers, understanding by short fibers those having an average length of less than 2 mm; and b) between 0.1% and 5.0% by weight of sodium carboxymethyl cellulose, and wherein: c) the weight of the filter paper per unit area is between 25 and 55 g/m.sup.2, measured according to UNE-EN ISO 536:2013 standard; d) the density of the filter paper, measured according to UNE-EN ISO 534:2012 standard in a single sheet, varies between 0.100 and 0.500 g/cm.sup.3; and e) the porosity filter paper is comprised between 1500 and 8500 ml/min.Math.cm.sup.2.Math.kPa, measured according to UNE-EN ISO 2965:2019 standard.

2. A paper filter comprising the filter paper according to claim 1.

3. The paper filter according to claim 2, wherein said paper filter has: a) a diameter between 5 and 8 mm; b) a weight between 0.050 and 0.200 g measured according to UNE-EN ISO 536:2013 standard; c) a hardness between 70% and 95%; d) a pressure drop between 0.490 and 1.471 kPa, measured according to UNE-EN ISO 6565: 2011 standard.

Description

PREFERRED EMBODIMENT OF THE INVENTION

[0029] The values of the parameters that define the claimed paper filter corresponding to measurements of different samples of conventional filters (available on the market) are provided below, classified into cellulose acetate filters (table 1) and paper filters (table 2):

TABLE-US-00001 TABLE 1 Commercially available cellulose acetate filters Pressure drop, Weight, g Diameter, Length, Hardness, mm w.g., 15 Pressure (15 mm) mm mm % mm drop, kPa 1 0.074 5.6 15 66.2 92.4 0.906 2 0.066 6.0 15 65.4 64.6 0.633 3 0.067 6.0 15 80.3 68.2 0.669 4 0.074 5.7 15 83.2 77.5 0.760 5 0.086 5.6 15 77.9 89.4 0.877 6 0.071 6.0 15 79.3 71.9 0.705 7 0.074 5.5 15 87.0 95.3 0.935 8 0.050 5.6 15 79.1 80.1 0.785 9 0.066 6.0 15 82.4 64.6 0.633 10 0.073 6.0 15 79.0 59.5 0.583 11 0.074 6.0 15 82.8 52.5 0.515 12 0.073 6.0 15 79.5 60.5 0.593 13 0.107 6.0 15 76.7 49.6 0.486 14 0.087 6.0 15 81.3 131.4 1.289 15 0.059 6.0 15 87.3 72.8 0.714 16 0.081 6.0 15 87.3 67.1 0.658 Average 0.074 5.9 15 79.7 74.8 0.733

TABLE-US-00002 TABLE 2 Commercially available paper filters Pressure drop, Weight, g Diameter, Length, Hardness, mm w.g., 15 Pressure (15 mm ) mm mm % mm drop, kPa 1 0.083 6.0 15 68.8 85.4 0.837 2 0.082 5.9 15 65.0 86.1 0.844 3 0.089 5.5 15 79.0 105.7 1.037 4 0.092 6.1 15 77.2 80.2 0.786 5 0.092 6.0 15 75.8 87.5 0.858 6 0.085 6.1 15 71.8 99.2 0.973 7 0.052 5.7 15 82.1 82.9 0.813 8 0.097 6.0 15 74.8 84.0 0.824 9 0.077 6.0 15 72.5 83.2 0.816 10 0.091 6.0 15 74.5 100.7 0.987 11 0.082 6.1 15 66.7 88.1 0.864 12 0.104 6.0 15 79.5 80.3 0.787 Average 0.086 5.9 15 74.0 88.6 0.869

[0030] The tables above show that, to achieve a similar hardness, although still inferior to the hardness of cellulose acetate filters, paper filters must have a higher pressure drop (approximately 18%). This fact, added to the greater retention of smoke components by the paper filter, has a negative impact on the taste of the cigarette.

[0031] The developed paper filter solves this problem since it provides a higher level of hardness than conventional paper filters, with a very slightly higher pressure drop than the one achieved when using cellulose acetate filters.

[0032] Below is a comparison of the results of the experimental tests carried out to demonstrate the properties of the claimed paper filter:

TABLE-US-00003 TABLE 3 Comparison of the results of commercial paper filter vs. claimed paper filter Pressure drop mm w.g. Hardness, % Weight, g Diameter, mm n = 60 n = 60 n = 6 n = 60 Average CV Average CV Average CV Average CV Claimed paper 61 7.5 89 3.0 0.103 0.3 5.98 0.6 filter, (0.598 kPa) 130 mm Commercial 70 8.9 78 4.2 0.084 0.7 5.92 2.2 paper filter 1, (0.686 kPa) 140 mm Commercial 66 10.3 80 6.6 0.074 2.4 5.92 1.2 paper filter 2, (0.647 kPa) 160 mm

[0033] The tests were carried out using paper filters 90 mm long with a diameter of 6 mm. The measured pressure drops and weights were adjusted to a 15 mm long rod.

[0034] In the tests carried out, it was shown that both commercial paper filter 1, and commercial paper filter 2, showed considerable fiber detachment, unlike the claimed paper filter which, due to its composition, showed greater structural stability.

[0035] The test was repeated with a sample of 60 cellulose acetate filter rods using the same machine. As in the case of the values found in table 3, in this case, the manufactured rods were also 90 mm long with a diameter of 6 mm. The measured pressure drops and weights were adjusted to a 15 mm long rod. The results were the following:

TABLE-US-00004 TABLE 4 Comparison of the results of commercial cellulose acetate filter vs. the claimed paper filter Pressure drop mm w.g. Hardness, % Weight, g Diameter, mm n = 60 n = 60 n = 6 n = 60 Average CV Average CV Average CV Average CV Claimed paper 61 7.5 89 3.0 0.103 0.3 5.98 0.6 filter (0.598 kPa) Commercial 59 3.9 82 1.9 0.073 1.1 6.02 0.4 cellulose acetate (0.579 kPa) paper filter

[0036] Table 3 shows the comparison between the filters produced with the claimed paper and those produced with commercial papers with two different widths. Table 4, in turn, shows the comparison of the results obtained with the same filter produced with the claimed paper shown in table 3 and a cellulose acetate filter produced in the same machine. As it can be observed, the level of hardness achieved is significantly higher than those of commercial paper filters and the cellulose acetate filter, with a pressure drop very slightly higher than that of the cellulose acetate filter.