EA013577B1 - Templated carbon fibers and their applications - Google Patents

Abstract

A carbon fiber is disclosed with a template derived shape and method for making the same by (a) mixing a precursor 30 with a fibrous template 26A, (b) forming the mixture into a pre-determined shape, (c) curing the mixture to form a precursor composite, (d) carbonizing the precursor composite, and (e) decomposing the fibrous template.

Description

BACKGROUND OF THE INVENTION

Carbon fibers have a wide range of applications. For example, ϋδ 6387479 and ϋδ 6277771 describe their use for reinforcing composite materials. Additionally, ϋδ 6037400 describes their use in microwave protection. In addition, ϋδ 6162533 also describes their use in the electrode structure. Other applications are also well known, as described in the prototype. For example, activated carbon fibers are used as filter media for gas separation (including the removal of gas phase constituents from cigarette smoke), catalytic adsorption, purification of waste streams or contaminated vapors, and elimination of unpleasant odors.

Carbon products are currently obtained by carbonization of precursor materials such as petroleum sands, polyacrylonitrile, cellulose and phenolic resins. For example, ϋδ 4917835 in the name of Beat et al. Discloses a method for producing porous molded carbon materials based on phenolic resins. However, the poor rheological and mechanical properties of carbon precursor materials limit the production and processing of carbon fibers into desired forms. In addition, the poor mechanical properties of the precursors or the resulting carbon fibers also limit the formation of a suitable medium for filtration applications.

Carbon is known for use in cigarette filter elements due to its ability to filter or remove constituents from exhaled smoke. In particular, activated carbon tends to lower the levels of certain components of the gas phase present in exhaled smoke, which leads to a change in the organoleptic and toxicological properties of such smoke.

Examples of filter segments containing activated carbon are described in ϋδ 2881770 in the name of Tocheu, ϋδ 3353543 in the name of δρΓοχΊΙ and others, ϋδ 3101723 in the name of δе1 ^ дтаη and others, and υδ 4481958 in the name of Vashet et al. Some commercially available filters have particles or carbon granules, such as activated carbon, individually or dispersed in a cellulose acetate tow, other commercially available filters have carbon filaments dispersed in them, while other other commercially available filters have so-called stub-space designs gas plug ”,“ filter with a cavity ”or“ triple filter ”. Examples of commercially available filters are δθδ IV a double solid charcoal filter and a triple solid charcoal filter from ITopa 1i1t1pa1yupa, b1b., A triple filter with a cavity from Waitabpet and AST from Intopa 1p1t1la1yupa, b1b. Details of the consideration of the properties and composition of cigarettes and filters are disclosed in ϋδ 5404890 and ϋδ 5568819 in the name of Oepbu and others, the descriptions of which are given by reference.

It would be desirable to provide a cigarette filter containing carbon fibers and / or other materials capable of absorbing and / or adsorbing gas phase components while creating favorable processing, processing, absorption / adsorption, dilution, and, in the case of cigarette filters, drawing characteristics so that to be suitable for consumers. However, no method that currently exists provides such a filter. In addition, commercially available activated carbons and molecular sieves are usually found in granular and powder forms. The materials in these forms do not preserve the cohesion of the product, since granules and grains tend to precipitate after packing inside a cigarette filter. Therefore, it is also desirable to obtain activated carbon fibers with improved product integrity.

SUMMARY OF THE INVENTION

According to an embodiment of the present invention, carbon fiber and activated carbon fiber with the desired cross-sectional shapes are developed when creating their shapes from preformed patterns.

Furthermore, in accordance with an embodiment of the invention, molded carbon fibers are created that have advantages in reinforcing materials, electrical and other applications.

In addition, in accordance with a preferred embodiment of the invention, activated carbon shaped fibers with desired cross-sectional shapes are provided that provide an effective cigarette filter with high ODM production, low pressure drop and improved gas phase removal efficiency. Preferred shaped shapes include, but are not limited to, multi-leaf shapes, such as a three-leaf shape and a four-leaf shape, a ν-shape, a stylized Ι shape, or a nested stylized Ι shape, a Shaped shape and an irregular shape.

In addition, according to a preferred embodiment of the invention, the activated carbon fiber material is formed with adjustable fiber orientation and packing density, which are critical for achieving exceptional performance in various applications. Preformed patterns are provided with carbonizable material and can be processed into woven and non-woven shapes with the desired fiber orientation and packing density. The activated carbon filter material with adjustable fiber orientation and packing density can then be formed by curing, carbonizing and activating carbon fibers or fibers from a carbonizable precursor.

In addition, in accordance with a preferred embodiment of the present invention, shaped coal

- 1 013577 native fibers with adjustable cross-sectional shapes provide cigarette filters that are effective in reducing the content of gas phase components in inhaled smoke.

Brief Description of the Drawings

New features and advantages of the present invention, in addition to the above, will be apparent to those skilled in the art from reading the following detailed description in conjunction with the accompanying drawings, in which like symbols refer to like parts, and in which in FIG. 1 is a sectional side view of a cigarette with parts discarded to show internal parts, including a plug-space-plug filter with a carbon filter according to the present invention;

in FIG. 2 is a sectional side view of a cigarette with parts discarded to show internal parts, including a plug-space filter with a carbon filter according to the present invention;

in FIG. 3 is a cross-sectional view of a template coated and impregnated with a precursor;

in FIG. 4 shows a cross section of a template with a predecessor after cleaning the template;

in FIG. 5 is a cross-sectional view of a three-leaf fiber pattern according to the present invention;

in FIG. 6 is a cross-sectional view of a four-leaf fiber pattern according to the present invention;

in FIG. 7 is a cross-sectional view of an ν-shaped fiber pattern according to the present invention;

in FIG. 8 is a cross-sectional view of a 1-shaped fiber pattern according to the present invention;

in FIG. 9 is a cross-sectional view of a C-shaped fiber pattern according to the present invention;

in FIG. 10 is a cross-sectional view of an irregularly shaped fiber pattern according to the present invention;

in FIG. 11 is a perspective view of two of the four carbon fibers that remain after carbonization of the precursor and decomposition of the four-leaf template shown in FIG. 3 and 4;

in FIG. 12 is a graph showing acrolein production in puff of 1K4E cigarettes and filter cigarettes made according to the present invention; and in FIG. 12 is a graph showing the production of 1,3-butadiene in puffs of 1K.4E cigarettes and filter cigarettes made according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will now be described with reference to the drawings.

In FIG. 1 shows a stub-space-stub filter. The cigarette 10 comprises a first plug 12, a space 14, a second plug 16, tobacco 18 and paper 20. The filter plug-space plug is adjacent to the tobacco 18. The user lights the end with paper 20 and tobacco 18 at the end opposite from the filter. Air and particulate material are then drawn to the filter by the user. The space 14 may be filled with material 22, such as carbon, and may have voids, channels or openings 24.

Other filter arrangements are possible. For example, in FIG. 2 shows a stub-space filter device. The filter is similar to the filter shown in FIG. 1, but the cigarette 10 instead contains a plug 12, a space 14, tobacco 18 and paper 20. The filter plug-space is adjacent to the tobacco 18. Like the embodiment shown in FIG. 1, space 14 may be filled with material, such as carbon 22, and may have voids, channels, or openings 24.

According to a preferred embodiment of the present invention, shaped carbon fibers are obtained by loading carbon precursor materials, such as phenolic resins, into fiber forming patterns made of low carbon yield materials, such as polypropylene, which contain longitudinal channels, as will be discussed in detail below with respect to FIG. . 3 and 4; curing the loaded carbon precursors within the channels of the patterns to form composite fiber precursors; carbonization of composite fiber precursors in an inert atmosphere or in vacuum; and decomposing the shape-adjusting patterns to form shaped carbon fibers with adjustable cross-sectional shapes, as will be discussed in detail below with respect to FIG. eleven.

The fiber pattern 26 may have a cross section with a shape including (but not limited to) the shapes shown in FIG. 5-10, which may be described as a three-leaf shape, four-leaf shape, ν-shape, stylized Ι-shape or nested stylized Ι-shape, C-shape and irregular shape, respectively. Patterns may be

- 013577 molded and obtained by extrusion, spinning or another molding method, as described, for example, in I8 5057368 in the name of Lagdai and others. Template 26 can be made of any polymeric material and can leave only a small amount of residue, for example, zero coal yield during thermal decomposition. The preferred template material 26 is polypropylene (NI). The cross-sectional shape of the template 26 provides longitudinal channels 26 that can be continuous and which are open to the surface of the template 26.

The carbon precursor 30 may contain solids, gels, foams, liquids, or mixtures thereof, which produce carbon or carbon materials when heated at a carbonization temperature in an inert atmosphere or in vacuum. Suitable materials of these classes include, but are not limited to, phenolic resin, petroleum pitch, polyacrylonitrile, cellulose, cellulose derivatives, polyvinyl acetate (PVA), and mixtures thereof. Molecular sieves, zeolites and silicates or other additional inorganic materials may be included in the mixture to modify the distribution of the final carbon products. Proposed phenolic resins may be uncured or partially cured novolac type resins with the presence of curing agents or a resol (self-curing) type, or a mixture thereof. In the mixture, the particulate partially cured resin, as described in I8 4917835 in the name of Beat et al., Can be used as described, or only to bind the components.

Precursor 30 is mixed with fiber patterns according to well-known technology, as described in I8 6584979 and I8 5772768 in the name of Hie et al.

As shown in FIG. 5-10, patterns 26-26E have voids or channels 28. Precursor 30 is loaded into channels 28 by mixing shaped patterns 26-26E with predecessor 30 in a container (not shown). For example, in FIG. 3 shows the loading of the four-leaf template 26A by the precursor 30. The template is first placed, immersed, dropped or dragged through a container containing the precursor (not shown). Some levels of mixing or rotation of the container may be necessary to achieve a homogeneous impregnation of the channels, as shown in the related application ϋδ 10/294346, incorporated herein by reference. The mass ratio of the carbon precursor to the polypropylene pattern, also called the loading index, is preferably (but not limited to) in the range of 0.25-2. When gels, suspensions or viscous liquids are used as carbon precursors, a certain amount of a liquid solvent, such as ethanol, can be used to adjust the viscosity to ensure homogeneous impregnation.

As further shown in FIG. 3, an excess of the precursor 30 may be located outside the channel 28, which can be removed from the outside of the template 26A by any well-known method, including (but not limited to) rinsing, washing in a solvent, wiping, draining or blowing. For example, the excess precursor 30 that remains outside the channels 28 or on the template 26 can be removed by wiping the filaments with a paper towel, pad, cloth, or other suitable means containing a solvent, such as ethanol. After this operation, the precursor 30 remains in the channel 28, as shown in FIG. 4.

Curing conditions can be chosen so that the template 26 retains structural and / or chemical integrity, while the carbon precursor 30 cures within the template 26 to form a non-flowing resin. Conditions can be selected based on the components in the carbon precursor, especially the uncured components used as the binder. As shown, for example, in table. 1, PP templates and a phenolic resin carbon precursor can be used to implement the present invention. The precursor can be cured by heating in the atmosphere at a temperature of from about 120 to 160 ° C for about 1560 minutes. A certain amount of acid may be added to the phenolic precursors to accelerate curing.

In the carbonization step, the cured composite fiber precursors can be heated in an inert medium and / or in vacuum to decompose the template and to provide shaped carbon fibers 32 from the carbon precursor, as shown in FIG. 11. For example, carbonization can be carried out by heating the carbon precursor to a temperature in the range of about 600-950 ° C. for about 30 minutes to 4 hours, although the temperature and time can vary to achieve the desired results in any particular situation. In FIG. 11 shows the molded carbon fibers 32 that remain after decomposition of the template shown in FIG. 3 and 4. Molded carbon fibers 32 derive their shapes from the shapes of patterns 26 and therefore may also be referred to as “shaped carbon fibers”. Parts 34 may remain in the area between extensions 26A that the cleaning does not remove.

In the table. 1, 7 examples are presented using various patterns and processing conditions to produce different channels. In the examples, carbonization can be carried out by heating the materials in a stream of nitrogen or argon at a temperature of about 850 ° C for about 1-2 hours, where a carbon precursor based on a phenolic resin and PP template are used. The carbon yields are usually in the range of 10-40% wt. depending on the PP content of composite precursors.

- 3 013577

Table 1. Carbon products obtained in accordance with the present invention

Method example Shaped Fiber Matrix Index downloads Curing at 150 ^° C Carbonation at 850 ° C The carbon fiber WD / MXM min h Exit, % The form ND / μm one S-2Hard / filament 33-36 0.48 40 2 33 Round 43-57 2 Wrong - 16 denier / filament 15-75 0.60 fifteen 2 23 Wrong 10-50 4 Trilobal-24 denier / filament 26-40 0.76 fifteen 2 22 Pentagonal 24-50 5 C-24day / filament 34-37 0, 38 thirty one 10 Round 40-60 b C-24day / filament 34-37 0.81 thirty one 17 Round 40-60 7 ν-24day / filament 40-51 sixteen fifteen one 24 Triangular 35-40 8 ν-24day / filament 40-51 sixteen fifteen one 23 Triangular 33-40

For examples, the polypropylene pattern is mixed with a phenolic resin carbon precursor. For examples 7 and 8, Ε1ΘΗ is used in the formulation of the phenolic precursor to reduce viscosity. Use 16-24 denier / filament patterns (brOs that contain channels with an inner diameter or inner size (ID) of about 10-60 microns. The patterns have a loading index in the range of 0.38 to 1.6. Curing occurs at a temperature of approximately 150 ° C. in about 15-40 minutes To reduce the specified curing time, a certain amount of acid may be added to the phenolic precursor .. Carbonization is carried out at a temperature of approximately 850 ° C. for about 1-2 hours. o in the range of 10-24 wt.% depending on the PP content of the composite precursors. Carbon fibers get their shape and outer diameter or outer size (OD) from the shape and VD of the template, respectively. The interval given for ND and VD reflects the flexibility pattern and characteristics of various cavities 28. For example, some of the cavities have different sizes in different directions.

It should be noted relative to the table. 1 that the ND of the carbon fiber part exceeds the VD. This result is due to the fact that the template material is flexible, and thus, the predecessor can strengthen the VD, which was measured before loading, from the outside. In addition, a certain amount of the precursor may be between the expanding parts of the template, which are not used in the calculation of VD. For example, in FIG. 11 shows zones 34 which are not contained in the VD of the four-petalled surface, but which contribute to the achieved ND.

Shaped carbon fibers can be activated to form absorbent materials with a high surface area for filtration applications. Many activation methods are known in the literature, such as heating with CO ₂ or steam. Activation can be achieved by maintaining the temperature in the range of about 800-950 ° C for about 30 minutes. For example, shaped carbon fiber from example 5 in table. 1, CO ₂ can be activated at a temperature of approximately 950 ° C. for approximately 30 minutes. At 25% burnup, the surface area by the BET method of 1557 m ² / g and the micropore volume (<20 A) of 0.6415 cm ³ / g can be obtained. These values are comparable to those of coconut-based activated carbon granules, which are often used as absorbers in cigarette filters.

Modified C4E cigarette models containing 66 mg and 150 mg of activated shaped carbon fibers are prepared with the configurations shown in FIG. 1 and 2, respectively. For the 66 mg model, the cap 12 has a length of 12 mm, the carbon article 22 has a length of 8 mm, and the second cap 16 has a length of 7 mm. For the 150 mg model, plug 12 is 10 mm long and carbon product 22 is 17 mm long. Cigarettes are smoked under ЕТС conditions, when the chemical composition of the smoke is analyzed by the methods of ICPSP (IR spectroscopy with Fourier transform) and GC-MS (gel chromatography-mass spectroscopy). As shown in the table. 2-3 and in FIG. 12 and 13, the filters obtained in accordance with the present invention are effective in reducing a wide range of smoke gas phase components when used to filter cigarette smoke.

In the table. 2, a standard 1K4E cigarette is compared with a cigarette containing a carbon product according to the present invention under the processing conditions described in Example 5 of Table 1. 1. Cigarette SH4E is a KeShisku reference cigarette with a filter provided by the 111th Tobasso apb NeaI Kskeatsy 1p81y1e, Ishuegayu o Kep1isku for research purposes. In the first row of the table. 2 shows the characteristics of the control sample Ш4Е. which are relatively typical characteristics of a control cigarette. In the second and third rows of the table. 2 shows the characteristics of the modified TE-66-1 and TE-66-2 cigarettes, respectively, which were obtained in accordance with the present invention, the characteristics being presented as a percentage difference in characteristics from the control sample 1K4E. Modified samples of TE-66-1 and TE-66-2 are cigarettes with the structure shown in FIG. 1, in which the plug 12 is 12 mm, the plug 16

- 4 013577 is 7 mm, and the carbon product 24 is 5 mm in length along the axis. The carbon product has a mass of 66 mg. However, the indicated values are only exemplary, and any lengths and / or masses can be selected.

In the table. Figure 2 shows the ODM values for sample 1K4P. The standard deviation is given for sample data 1Я4Р. The values presented for the modified samples TP-66-1 and TP-66-2 are given as a change from the 1Я4Р-standard. A change that exceeds more than three times the standard deviation of the 1P4P control sample is considered significant. As shown in the table. 2, the contents of acetaldehyde (AA), methanol (MeOH) and isoprene (Ι8ΟΡ) in the total dispersed material (DM) are all reduced as a result of using the present invention. The content of cyanide (NSA) is slightly increasing, but slightly.

Table 2. Modified cigarette samples compared to a control cigarette

Sample AA (ODM) ΗΟΝ (ODM) Meon (ODM) Ι5ΟΡ (ODM) ODM (mg) Resist nie suction Carbon Filter Weight (mg) 1K4E control (TRMhU ' ³ ) standard deviation 51.5 9.2 6.2 23.7 8% 4% 98% 8% 13.3 3% 140 5% 0,0 TG-66-1 -43% 4% -35% -54% 7.2 162 66 TG-66-2 -72% 9% -40% -62% 7.0 159 66

In FIG. 12 and 13 further illustrate how samples modified according to the present invention reduce the puff production of acrolein and 1,3-butadiene. In FIG. 12 shows the production of acrolein in a puff of modified 1H4P cigarettes in comparison with TP-66 and TP-150 samples. In FIG. Figure 13 shows the puff production of 1,3-butadiene of modified 1K4P cigarettes compared to TP-66 and TP-150 samples.

For example, in FIG. Figure 12 shows the amount of acrolein in exhaled smoke for various puffs of LKZ-R Keplisku-reference cigarettes and modified samples. Acrolein in cigarette smoke is determined in relation to one puff. Cigarettes are smoked with a puff volume of 35 cm ^{3 for} two seconds every 60 s. Puff acrolein production is recorded for 8 1K4P determinations, as well as for modified samples. As shown in FIG. 12, the first puff is from 15 to 20% of the total output of 1H4P, but usually about 0 for modified samples. The tightening process is repeated more than 7 times in accordance with well-known and repeatable methods to obtain the graph shown in FIG. 12. A similar method is used to determine the production of 1,3-butadiene.

As shown in FIG. 12 and 13, the content of the constituent gases increases with each puff as a result of saturation of the filter. However, the production of acrolein and 1,3-butadiene is lower for a sample created using the present invention. Indeed, the production of acrolein and 1,3 butadiene in the samples is almost zero for the first few puffs.

In the table. 3 further shows the advantages of the present invention. The first column presents the characteristics and components common to cigarettes and cigarette smoke. The second column, entitled “1H4P standard deviation”, presents the standard deviation of some components of the gas phase present in the control 1H4P cigarette. The columns named TP-66 and TP-150 show the changes in the levels of the component in the gas as a result of the use of filters made in accordance with the present invention, and in particular, example 5 of table 1.

- 5 013577

Table 3. Change in gas phase components

Adsorbent - Runs 1E4G standard deviation TG-66 TR-150 Carbon fiber / mg Ν * standard 66 9627-798 152 9645-17 Gas phase components Change Change Carbon dioxide 5% Minor change Minor change Propylene 9¾ Minor change -60% Hydrogen cyanide thirteen% -34% -83% Ethane 6% Insignificant change Insignificant change Propadiene thirteen% -36% -71% 1, Z-Butadiene 8% -77% -97% Isoprene 5% -97% -98% Cyclopentadiene 5% -96% -98% 1, Z-Cyclohexadiene 17% -one hundred% -one hundred% Methyl cyclopenta diene nine% -one hundred% -99% Formaldehyde 14% -95% -87% Acetaldehyde nine% -84% -97% Acrolein 14% -78% -95% Acetone 12% -one hundred% -one hundred% Diacetyl 5% -one hundred% -one hundred% Methyl ethyl ketone 4% -one hundred% -one hundred% Isovalerian Aldehyde nine% -98% -97% Benzene 8% -one hundred% -99% Toluene 7% -one hundred% -99% Butyronitrile 8% -] 00% -one hundred% 2-methylfuran 4% -one hundred% -99% 2,5-dimethylfuran 5% -one hundred% -99% Hydrogen sulfide 7% -67% -89% Carbonyl sulfide 6% Insignificant change -38% Methyl mercaptan 6% -71% -85% 1-methylpyrrole 8% -one hundred% -98% Keten eleven% -one hundred% -93% Acetylene thirteen% -39% -43%

The above description of the invention illustrates and describes the present invention. In addition, the description shows and describes only preferred embodiments of the present invention, but it should be understood that the present invention is capable of using various other combinations, modifications and conditions and is capable of changes or modifications within the scope of the concept of the invention, as expressed herein, in accordance with the foregoing description and / or qualifications or knowledge in the field of obtaining filters and, in particular, obtaining cigarette filters.

The options described above are also intended to illustrate the best known embodiments of the invention and to enable other specialists in the art to use the invention in these or other embodiments and with other modifications required by specific applications or uses of the invention. Accordingly, the description is not intended to limit the invention as contemplated herein. It is also intended that the appended claims be construed as including alternatives.

Claims (16)

CLAIM 1. The method of forming carbon fiber, comprising mixing the carbon precursor with the fiber pattern so that the carbon precursor is formed in the cavity formed by the shape of the template; curing the mixture to form a precursor composite with a stable form; carbonizing the precursor composite; and decomposing the fiber pattern to form carbon fiber formed by the cavity of the fiber pattern. 2. The method according to claim 1, wherein the fiber pattern contains polypropylene. 3. The method according to claim 1, wherein the carbonization is carried out in an inert atmosphere, in vacuum or in a combination thereof. 4. The method according to claim 1, wherein the stage of carbonization and the stage of decomposition takes place simultaneously. 5. The method according to claim 1, wherein the formed carbon fiber has the shape given by the pattern. 6. The method according to claim 1, wherein the carbon precursor is a phenolic resin. 7. The method according to claim 1, in which the carbon fiber is activated by heating in the presence of CO ₂ or water vapor. 8. The method according to claim 7, in which the activation takes place at a temperature in the range of from about 800 to about 950 ° C for about 30 minutes 9. The method according to claim 1, in which the outer part of the template is cleaned so that the precursor mainly remains only in the cavity formed in the cross section of the template. 10. The method according to claim 1, wherein a solvent is used to adjust the viscosity of the precursor during the mixing process. 11. A filter containing shaped carbon fiber having a four-lobe form, three-lobe form, Y-shaped, stylized Ι-shaped, nested stylized-shaped or C-shaped cross-section. 12. A cigarette containing a filter according to claim 11. 13. Shaped carbon fiber having a four-lobe form, three-lobe form, Y-shaped, stylized Ι-shaped, nested stylized Ι-shaped or C-shaped cross-section. 14. A smoking article comprising a cap, a carbon filter according to claim 11, and a tobacco rod. 15. A method of forming carbon fiber, comprising mixing a template of fiber containing polypropylene with a carbon precursor containing a phenolic resin, so that the carbon precursor is molded in a cavity formed by the form of the template; cleaning the perimeter of the template; curing the mixture at a temperature of approximately 120-160 ° C for approximately 15-60 minutes with the formation of a composite precursor with a stable form; carbonizing the precursor composite at a temperature in the range of from about 600 to about 950 ° C. and decomposing the fiber pattern to form carbon fiber formed by the cavity of the fiber pattern. 16. The method of claim 15, further comprising activating carbon fiber by heating the fiber in the presence of CO2 or water vapor at a temperature in the range of from about 800 to about 950 ° C for about 30 minutes.