JP2018027881A - Titanium dioxide-containing slurry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a titanium dioxide slurry that is well incorporated into cellulose acetate of a tobacco filter.SOLUTION: A titanium dioxide-containing slurry is formed which contains 30-60 wt.% of titanium dioxide, 39-69 wt.% of water, and 0.1-1 wt.% of one or more additives based on the total weight of the slurry and is stored stably for at least 4 days. The slurry can be a slurry of water or acetone and the slurry has a D[4,3] and D[0.9] particle size distribution of less than 1 μm after storage at ambient temperature for 4 days. The slurry can be incorporated into a cellulose acetate dope and the cellulose acetate dope is then processed into a tobacco filter through a large number of downstream processing steps.SELECTED DRAWING: None

Description

Priority claim
[0001] This application claims priority to US Provisional Patent Application No. 62 / 334,054 filed May 10, 2016, which is incorporated herein by reference in its entirety. .

  [0002] The present invention relates generally to slurries containing titanium dioxide. In particular, the invention relates to a slurry comprising titanium dioxide having a particle size distribution of less than 1 μm based on various measurement methods after storage at ambient temperature for 4 days. The slurry can be incorporated into a cellulose acetate dope that can be spun to form a filament, and finally into a cellulose acetate tow used in tobacco filters.

  [0003] Cellulose acetate tow is commonly used in the manufacture of tobacco filters. During tow production, a matting agent, typically titanium dioxide, is incorporated in various processing steps to impart a predetermined opacity to the final tobacco filter. Titanium dioxide can also be used to promote photolysis of tobacco filters, an important consideration for minimizing littering problems associated with the disposal of used tobacco. Titanium dioxide is most often formulated into a slurry and then added to the cellulose acetate dope before forming the tow. There is a problem with the particle size distribution within the slurry, especially due to particle aggregation. Larger titanium dioxide particles can increase tow scattering and accelerate wear of the extrusion apparatus. Although filtering can be used to remove particles larger than the desired size, this filtering can reduce the desired titanium dioxide content in the final tobacco filter, resulting in substandard products and operating costs. Cause an increase.

  [0004] US Pat. No. 5,491,024, which is incorporated herein by reference in its entirety, contains 0.05 to 5 cellulose esters and titanium dioxide having an average particle size of less than 100 nanometers. An artificial fiber containing 0.0 weight percent is disclosed. The fiber is used in photodegradable cellulose ester tow.

  [0005] US Pat. No. 5,647,383, which is incorporated herein by reference in its entirety, includes tobacco columns and artificial fibers containing cellulose esters and has an average particle size of less than 100 nanometers Tobacco with a filter containing 0.05 to 5.0% by weight of titanium dioxide is disclosed.

  [0006] US Patent No. 5,491,024 and US Patent No. 5,647,383 both suggest that the aggregation of titanium dioxide particles should be minimized or reduced. Do so to maximize photosensitivity.

  [0007] U.S. Pat. No. 4,288,254, which is incorporated herein by reference in its entirety, is at least about by mixing rutile titanium dioxide, at least one dispersant, and water. A method of preparing a dispersion-coated rutile titanium dioxide slurry having a solids content of 60% by weight; the dispersion-coated titanium dioxide slurry deagglomerates the titanium dioxide, but the coating is pulled from the titanium dioxide. A method of directly passing through a high shear mill having an impeller peripheral speed sufficient to prevent peeling; and a method of recovering a rutile-type titanium dioxide slurry having a solids content of at least 60 wt. Is directed to. The slurry can be used in aqueous paints that require relatively high solids.

  [0008] United States Patent Publication No. 2014/0261086, which is incorporated herein by reference in its entirety, is directed to a method of producing a titanium dioxide pigment. The method includes preparing an aqueous slurry of titanium dioxide particles. The method further includes deagglomerating the aqueous slurry of titanium dioxide particles using sonication.

US Pat. No. 5,491,024 US Pat. No. 5,647,383 U.S. Pat. No. 4,288,254 US Patent Publication No. 2014/0261086 U.S. Pat. No. 2,740,775 US Patent Publication No. 2013/0096297 US Patent Publication No. 2013/0192613 U.S. Patent No. 7,585,442 US Patent No. 7,610,852

  [0009] Although the problem of agglomeration is recognized, there is a need for slurries and slurry forming methods that meet predetermined particle size distribution requirements even when stored for long periods of time. In particular, the slurry preferably has a particle size distribution of less than 1 μm when measured based on various measurement methods after being stored at ambient temperature for 4 days.

  [0010] In one embodiment, the present invention is a slurry comprising 30-60 wt% titanium dioxide, 39-69 wt% water, and 0.1-1 wt% one or more additives. And after storage at ambient temperature for 4 days, it is directed to a slurry having a D [4,3] and D [0.9] particle size distribution of less than 1 μm. In some embodiments, the slurry has a D [4,3] and D [0.9] particle size distribution of less than 1 μm after 8 days storage at ambient temperature or 18 days storage. One or more additives may be selected from the group consisting of dispersants, antibacterial agents, and combinations thereof. The titanium dioxide can be food grade titanium dioxide. Titanium dioxide can be coated with an inorganic coating. The inorganic coating can be an oxide or hydroxide of at least one element selected from the group consisting of aluminum, cerium, magnesium, silicon, titanium, zinc, and zirconium. Titanium dioxide can be treated with organic materials. The organic material may be selected from the group consisting of liquid and solid polyols, liquid polyphosphates, liquid hydroxyamines, liquid and solid styrene-maleic anhydride copolymers, and combinations thereof. In some embodiments, the organic material is selected from the group consisting of low molecular weight polyglycols, trimethylolpropane, triethanolamine, 2-amino-2-methyl-1-propanol, tetrapotassium pyrophosphate, and combinations thereof. The The increase in D [4,3] and D [0.9] particle size distribution can be less than 20% when stored at ambient temperature for 4 days.

  [0011] In another embodiment, the present invention is a slurry comprising 10-25 wt% titanium dioxide, 65-85 wt% acetone, and 5-10 wt% one or more additives. Are directed to a slurry having a D [4,3] and D [0.9] particle size distribution of less than 1 μm after storage at ambient temperature for 4 days. In some embodiments, the slurry has a D [4,3] and D [0.9] particle size distribution of less than 1 μm after 8 days storage at ambient temperature or 18 days storage. The one or more additives may be selected from the group consisting of dispersants, antibacterial agents, and combinations thereof. In some aspects, the one or more additives may include a viscosity modifier. The titanium dioxide can be food grade titanium dioxide. Titanium dioxide can be coated with an inorganic coating. The inorganic coating can be an oxide or hydroxide of at least one element selected from the group consisting of aluminum, cerium, magnesium, silicon, titanium, zinc, and zirconium. Titanium dioxide can be treated with organic materials. The organic material may be selected from the group consisting of liquid and solid polyols, liquid polyphosphates, liquid hydroxyamines, liquid and solid styrene-maleic anhydride copolymers, and combinations thereof. In some embodiments, the organic material is selected from the group consisting of low molecular weight polyglycols, trimethylolpropane, triethanolamine, 2-amino-2-methyl-1-propanol, tetrapotassium pyrophosphate, and combinations thereof. The The increase in D [4,3] and D [0.9] particle size distribution can be less than 20% when stored at ambient temperature for 4 days.

  [0012] In yet another embodiment, the present invention is a method of preparing a slurry comprising combining titanium dioxide, a liquid, and at least one additive to form a slurry, mixing the slurry, And pumping the slurry through a particle size reduction device, the slurry having a D [4,3] and D [0.9] particle size distribution of less than 1 μm after storage for 4 days at ambient temperature. Is directed to a method of having. The particle size reduction device may be selected from the group consisting of a pebble mill, a sand mill, a high shear pump, and a premix dispenser. The slurry may have a D [4,3] and D [0.9] particle size distribution of less than 1 μm after 8 days storage at ambient temperature or after 18 days storage.

  [0013] In yet another embodiment, the present invention provides a method for preparing a cellulose acetate dope comprising preparing a slurry comprising titanium dioxide, a liquid, and at least one additive, wherein the slurry Has a D [4,3] and D [0.9] particle size distribution of less than 1 μm after 18 days storage at ambient temperature; the slurry is mixed with cellulose acetate and a solvent to mix the cellulose acetate with the solvent Dissolving the slurry in to disperse; and filtering the cellulose acetate dope to remove solvent insoluble particles, wherein the cellulose acetate dope is 20-30 wt% cellulose acetate, 70-80 wt% % Solvent, and 0.05-3 wt% titanium dioxide, and less than 1 wt% titanium dioxide during filtering. It is directed to a method to be removed. In some embodiments, the slurry comprises 10-25 wt% titanium dioxide, 65-85 wt% acetone, and 5-10 wt% one or more additives. In other embodiments, the slurry comprises 30-60 wt% titanium dioxide, 39-69 wt% water, and 0.1-1 wt% one or more additives. The solvent can be selected from the group consisting of water, acetone, methyl ethyl ketone, methylene chloride, dioxane, dimethylformamide, methanol, ethanol, glacial acetic acid, supercritical carbon dioxide, and combinations thereof.

I. Introduction
[0014] The present invention relates to a slurry composition comprising titanium dioxide, a pigment commonly used as a matting agent in cellulose acetate tow. The slurry composition is prepared and stored for addition to the cellulose acetate dope and then formed into a tow. A predetermined amount of the slurry composition is added to the cellulose acetate dope. However, a problem in storage of the slurry is that the solid content in the slurry tends to aggregate and the particle size increases. As described further herein, the dope is subjected to several process steps including filtering and extrusion. This is a problem because if the particles aggregate during filtering, particles larger than the filter size are removed and the amount of titanium dioxide in the final product is reduced. In addition, particle agglomeration can form fragile spots in the fiber, which can cause more tow to scatter during the rod manufacturing process. Furthermore, downstream of the process steps, increasing the particle size can cause excessive wear on the crimper. Increasing the particle size in the slurry has undesirable effects that are dragged through the process, so the particle size is controlled to less than 1 micron so that the components of the slurry composition are not filtered out during the downstream process. This is highly desirable for slurry compositions. More desirably, the slurry composition has a particle size distribution that is relatively constant over time so that the slurry composition can be stored until needed.

  [0015] Accordingly, in some embodiments, the present invention provides 30-60 wt% titanium dioxide, 39-69 wt% water, and 0.1-1 wt% of one or more based on the total weight of the slurry. A slurry comprising a plurality of additives having a D [4,3] and D [0.9] particle size distribution of less than 1 μm after storage for 4 days at ambient temperature.

  [0016] In a further aspect, the present invention comprises 10-25 wt% titanium dioxide, 65-85 wt% acetone, and 5-10 wt% one or more additives, based on the total weight of the slurry. A slurry comprising a slurry having a D [4,3] and D [0.9] particle size distribution of less than 1 μm after storage at ambient temperature for 4 days.

  [0017] The present invention is also directed to a method of preparing a slurry. In some aspects, the method includes combining titanium dioxide, a liquid, and at least one additive to form a slurry, mixing the slurry, and pumping the slurry through a particle size reduction device. In that case, the slurry has a D [4,3] and D [0.9] particle size distribution of less than 1 μm after 4 days storage at ambient temperature.

  [0018] The present invention further includes a method of preparing a cellulose acetate dope. The method provides a slurry comprising titanium dioxide, a liquid, and at least one additive, wherein the slurry is stored at ambient temperature for 18 days and then has a D [4,3] and D [ 0.9] having a particle size distribution; mixing the slurry with cellulose acetate and a solvent to dissolve the cellulose acetate in the solvent and dispersing the slurry; and filtering the cellulose acetate dope to provide a solvent Removing the insoluble particles (usually acetone), wherein the cellulose acetate dope is 20-30 wt% cellulose acetate, 70-80 wt% solvent, and 0.05-3 wt% based on the total weight of the dope In addition, less than 1% by weight of titanium dioxide, including titanium dioxide, based on the total weight of the dope, is removed during filtering.

II. Slurry composition
[0019] The slurry includes titanium dioxide, a liquid, and at least one additive. Generally, the liquid is water that forms an aqueous slurry or acetone that forms an acetone slurry. The type and content of additives included depend on whether the slurry is an aqueous slurry or an acetone slurry.

  [0020] When the slurry is an aqueous slurry, the slurry is 30 to 60 wt%, such as 35 to 60 wt%, or 40 to 60 wt% titanium dioxide, and 39 to 69 wt%, based on the total weight of the slurry; Of, for example, 39-65 wt%, or 39-60 wt% water (generally deionized water). The aqueous slurry also includes 0.1 to 1 wt%, for example 0.2 to 0.9 wt%, or 0.3 to 0.8 wt% of one or more additives, based on the total weight of the slurry. obtain. The additive (s) is selected from the group consisting of a dispersant, an antimicrobial agent, and combinations thereof. Generally, the aqueous slurry does not contain any acetone.

  [0021] Suitable dispersants include alkaline polyphosphates, aliphatic carboxylic acids and their alkaline salts, polyacrylic acids and their alkaline salts, polyhydroxy alcohols, amino alcohols, and acrylic polymers. It is not limited to these. The acrylic acid polymer can be an acrylic acid homopolymer or acrylic acid copolymer, which is primarily acrylic acid, but maleic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, acrylamide, acrylonitrile, ethylene, propylene, styrene, and acid At least one comonomer selected from the group consisting of the esters of which the homopolymer or copolymer comprises a neutralizing agent having a monovalent group and at least one having a polyvalent group. It is partially or completely neutralized with a hydrating agent. The dispersant may be present in the slurry at 0.1 to 1 wt%, such as 0.1 to 0.8 wt%, or 0.2 to 0.6 wt%, based on the total weight of the slurry.

  [0022] Suitable antibacterial agents used in combination with the present invention include antibacterial metal ions, chlorhexidine, chlorhexidine salts, triclosan, polymyxin, tetracycline, aminoglycosides (eg gentamicin), rifampicin, bacitracin, erythromycin, Neomycin, chloramphenicol, miconazole, quinolone, penicillin, nonoxynol 9, fusidic acid, cephalosporin, mupirocin, metronidazole, cecropin, protegulin, bacteriocin, defensin, nitrofurazone, maphenide, acyclovir, vancomycin (clinocomycin) , Peroxides (eg, 20-40% strength hydrogen peroxide dilution), lincomycin, sulfonamido , Norfloxacin, pefloxacin, nalidixic acid, oxalic acid, enoxacinic acid, ciprofloxacin, polyhexamethylene biguanide (PHMB), PHMB derivatives (eg biodegradable biguanide-like polyethylene hexamethylene biguanide (PEHMB)), chlorhexidine gluconate Chlorohexidine hydrochloride, ethylenediaminetetraacetic acid (EDTA), EDTA derivatives (e.g. disodium EDTA or tetrasodium EDTA), and the like, and any combination thereof. The dispersant may be present in the slurry at 0.1 to 1 wt%, such as 0.1 to 0.8 wt%, or 0.1 to 0.6 wt%, based on the total weight of the slurry.

  [0023] When the slurry is an acetone slurry, the slurry is 10-25 wt%, such as 10-23 wt% or 10-21 wt% titanium dioxide, and 65-85 wt%, such as 67, based on the total weight of the slurry. May comprise -85 wt% or 70-85 wt% acetone. The acetone slurry may contain, for example, up to 10%, up to 5%, or up to 3% water by weight based on the total weight of the slurry. The acetone slurry may also contain 5 to 10 wt%, for example 6 to 10 wt%, or 7 to 10 wt% of one or more additives, based on the total weight of the slurry. The additive (s) can be a dispersant, an antimicrobial agent, or a combination thereof. In some embodiments, a viscosity modifier may be included as an additive. In a further aspect, the viscosity modifier is the only additive included in the acetone slurry.

  [0024] Suitable viscosity modifiers include, but are not limited to, water-soluble polymer compounds such as generally flaky substituted or unsubstituted cellulose esters. Cellulose ester is cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose tributyrate, cellulose propionate, cellulose tripropionate, cellulose acetate propionate, carboxymethyl cellulose acetate, carboxymethyl cellulose acetate propio Nate, carboxymethylcellulose cellulose butyrate, and cellulose acetate butyrate succinate, and combinations thereof. Viscosity modifiers can be present in the acetone slurry as 5 to 15 wt%, for example 6 to 15 wt%, or 7 to 15 wt% of one or more additives, based on the total weight of the slurry.

[0025] The titanium dioxide used in the acetone or aqueous slurry may be anatase, rutile, or mixed phase titanium dioxide. In some preferred embodiments, the titanium dioxide is anatase type. Without being bound by theory, the anatase type would be preferred because grinding is easier. As described herein, the particle size distribution of the slurry is generally 0.01-1 μm, such as 0.1-0.9 μm, 0.2-0.2, as measured by the Malvern D [0.9] method. The range is 0.8 μm or 0.4 to 0.6 μm. The specific surface area can range from 3 to 30 m ² / g. The particle size distribution and specific surface area can be selected based on downstream processing equipment requirements.

  [0026] Titanium dioxide can be coated with an inorganic coating. The inorganic coating may be formed from an oxide or hydroxide of at least one element selected from the group consisting of aluminum, cerium, magnesium, silicon, titanium, zinc, and zirconium.

  [0027] Titanium dioxide can be treated with an organic material. The organic material may be selected from the group consisting of liquid and solid polyols, liquid polyphosphates, liquid hydroxyamines, liquid and solid styrene-maleic anhydride copolymers, and combinations thereof.

  [0028] The inorganic coating is applied to the titanium dioxide before it is introduced into the slurry. Similarly, titanium dioxide is treated with an organic material before the titanium dioxide is introduced into the slurry. Thus, when titanium dioxide has an inorganic coating and / or is treated with organic materials, particle size distribution and specific surface area have already been taken into account in the coating and processing.

  [0029] To form a slurry, titanium dioxide is added to a liquid (eg, water or acetone) and mixed to evenly disperse. At the same time or after this addition, one or more additives are added to the liquid and mixed to evenly disperse. The slurry can then be pumped through a particle size reduction device. This step serves to reduce the size of any particles agglomerated during mixing and to correct any non-uniformities originating from the titanium dioxide source. The particle size reduction device may be selected from the group consisting of a pebble mill, a sand mill, a high shear pump, and a premix dispenser. Because of the reduction process during particle size reduction, the slurry can be heated to a maximum of 45 ° C., but the slurry is then cooled to ambient temperature during storage. Particle size reduction is a generally discontinuous process, but when used, the flow rate is 2.3-9.1 kg / min (5-20 lb / min), eg 3.2-6. It may range from 0.8 kg / min (7-15 lb / min), or 4.5-5.4 kg / min (10-12 lb / min). Lower flow rates than this range can cause damage to the titanium dioxide and any coating applied to it. When the flow rate is lower than this range, there is a possibility of excessive heat generation, and additives such as a dispersant may be inactivated. If the flow rate is higher than this range, the pulverization becomes too low and may cause poor particle distribution. In some embodiments, the slurry is sent only once through the particle reduction device. In a further aspect, the slurry is sent through the particle reduction device at least twice, such as three times or four times.

  [0030] The particle size distribution of the slurry can be measured before pumping through the particle size reduction device and at various times. Two particle size measurement methods, D [4,3] and D [0.9], are measured using, for example, Mastersizer 2000 sold by Malvern Instruments. Measurement is performed using laser diffraction. The D [4,3] measurement method represents the volume average diameter, and the D [0.9] measurement method represents that 90% of the particle volume has the indicated diameter or less.

  [0031] As noted above, the titanium dioxide may have an initial particle size distribution that is selected based on downstream processing requirements. For example, if downstream filtering removes particles greater than 1 μm, D [4,3] or D [0.9] particle size distribution of less than 1 μm, for example less than 0.8 μm or 0.4 to 0.6 μm. Titanium dioxide having the following is desirable. As the slurry is formed, the particles in the slurry have a tendency to agglomerate and the particle size distribution generally increases over time. By pumping the slurry through the particle size reduction device, the particle size distribution can be adjusted and controlled based on the settings of the particle size reduction device.

  [0032] The slurry is typically stored at ambient temperature, eg, 20-25 ° C., and ambient pressure, eg, 14.7 psi (101 pKa) at average sea level. Although the slurry can be used immediately after preparation, it is desirable to be able to store the slurry for future use. The slurry can be stored for at least 1 day, such as at least 4 days, at least 8 days, at least 12 days, at least 18 days, or at least 22 days. Slurries prepared based on the above disclosure have D [4,3] and D [0.9] particle size distributions of less than 1 μm after 4 days storage at ambient temperature. In some embodiments, the slurry has a D [4,3] and D [0.9] particle size of less than 1 μm after being stored at ambient temperature for 8 days, such as after 12 days, 18 days, or 22 days. Have a distribution. Furthermore, the increase in particle size distribution is less than 20%, for example less than 15% or less than 10% during a storage period of 4 days, based on both D [4,3] and D [0.9] measurement methods. possible. The increase in particle size distribution can be less than 20%, for example less than 15% or less than 10% during a storage period of 8 days, based on both D [4,3] and D [0.9] measurement methods. . The increase in particle size distribution can be less than 20%, for example less than 19% or less than 18% during a storage period of 18 days, based on both D [4,3] and D [0.9] measurement methods. . The increase in particle size distribution can be less than 20%, such as less than 19% or less than 18% during a storage period of 22 days, based on both D [4,3] and D [0.9] measurement methods. . If the particle size distribution is measured and the increase exceeds the desired amount, or if the particle size is too large, the slurry can be pumped through a particle size reduction device prior to use.

III. Cellulose acetate dope
[0033] Once the slurry is formed and stored until needed, it can be added to the cellulose acetate dope. The cellulose acetate dope is formed by dissolving cellulose acetate in a solvent to form a dope solution. The solvent is a group consisting of water, acetone, methyl ethyl ketone, methylene chloride, dioxane, dimethylformamide, methanol, ethanol, glacial acetic acid, supercritical carbon dioxide, any suitable solvent capable of dissolving the above polymers, and combinations thereof Can be selected. In some embodiments, the solvent is acetone or a combination of acetone and water, eg, up to 5% by weight water based on the total weight of the dope. The dope may comprise 20-30% by weight cellulose acetate and 70-80% by weight solvent. The dope further comprises 0.05 to 3 wt%, for example 0.05 to 2 wt% or 0.08 to 1 wt% titanium dioxide, based on the total weight of the dope. The amount of slurry added to the dope is determined by the titanium dioxide content in the slurry. When adding the slurry, the amount of acetone and / or water in the slurry is also considered so that a dope having the desired solvent content is produced.

[0034] The slurry can be added to the solvent simultaneously with dissolving the cellulose acetate or during a portion of dissolving the cellulose acetate, eg, until the end of the process. The solvent, cellulose acetate, and slurry are mixed to dissolve the cellulose acetate and disperse the slurry. The dope can be heated to a temperature of, for example, 45-70 ° C. to enhance mixing. Mixing can be performed under ambient or high pressure. High pressure is available when mixing occurs under a nitrogen blanket. The mixing time can range from 3 to 10 hours. Once the cellulose acetate is dissolved in the solvent, the dope is then filtered and degassed before being spun to form a filament. The degassing process can be performed under ambient or high pressure. High pressure is available due to the nitrogen blanket. The size of the filter can vary, but is selected according to downstream equipment and product specifications. In general, a typical dope flux is desirably a total extrusion product of 978 to 2441 g / hr per square meter of filtration area (0.2 to 0.5 pounds per hour per square foot). However, in general
[0035] The percentage of titanium dioxide in the dope can be measured after filtering. One technique for measuring the percentage of titanium dioxide is by using X-ray analysis, such as equipment sold by ASOMA Instruments. Due to the particle size distribution of the slurry described herein and its storage stability, it is less than 1% by weight of the titanium dioxide initially added to the dope, such as less than 0.9% by weight, less than 0.8% by weight, or Less than 0.7% by weight is removed during filtering. In some embodiments, less than 20%, such as less than 15%, less than 10%, less than 5%, or less than 1% of the titanium dioxide initially added to the dope is removed during filtering. This strict control of the titanium dioxide content makes it possible to achieve a product that meets the titanium dioxide standards for content and opacity. Furthermore, because the titanium dioxide particle size distribution is selected based on the size of the filter used in the dope step, the number of large titanium dioxide particles that pass through the filter and then to downstream process steps is reduced. Larger size titanium dioxide particles reduce fiber strength and increase wear of extrusion guides and crimping equipment, resulting in increased tow splashing and adversely affecting tow performance during rod manufacture. This is advantageous as it is believed to be obtained.

IV. Cellulose acetate filament and tow formation
[0036] Cellulose acetate flakes dissolved in the dope described herein are disclosed in US Pat. No. 2,740,775 and US Patent Publication No. 2013/0096297, which are incorporated herein by reference in their entirety. Can be prepared by known processes, including the process disclosed in. Although cellulose acetate is the most common cellulose ester used to form tobacco filters, alternative cellulose esters are also available. Alternative cellulose esters include cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose tributyrate, cellulose propionate, cellulose tripropionate, cellulose acetate propionate, carboxymethyl cellulose acetate, carboxymethyl cellulose acetate propionate , Carboxymethylcellulose cellulose butyrate, cellulose acetate butyrate succinate, and mixtures thereof.

  [0037] Generally, acetylated cellulose is prepared by reacting cellulose with an acetylating agent in the presence of a suitable acidic catalyst. Acylating agents may include both carboxylic acid anhydrides (or simply anhydrides) and carboxylic acid halogen compounds, especially carboxylic acid chlorides (or simply acid chlorides). Suitable acid chlorides include acid chlorides such as acetyl chloride, propionyl chloride, butyryl chloride, and benzoyl chloride. Suitable anhydrides include anhydrides such as acetic anhydride, propion anhydride, butyric anhydride, benzoic anhydride and the like. Mixtures of these anhydrides or other acylating agents can also be used to introduce different acyl groups into the cellulose. Mixed anhydrides, such as acetic acid propionic acid anhydride, acetic acid butyric acid anhydride, etc. may also be utilized for this purpose in some embodiments.

  [0038] In most cases, to produce a derivatized cellulose with a high degree of substitution with some additional hydroxyl group substitution (eg, sulfate ester), in some cases, the cellulose is used with an acetylating agent. Thoroughly acetylated. Thorough acetylation of cellulose means an acetylation reaction carried out thoroughly so that as many hydroxyl groups as possible in the cellulose undergo an acetylation reaction. When cellulose acetate is intended to be used in tobacco filters, the degree of substitution can be less than 3.0, preferably 2.2 to 2.8 or 2.4 to 2.6.

  [0039] Suitable acidic catalysts that promote acetylation of cellulose often include sulfuric acid or a mixture of sulfuric acid and at least one other acid. Other acidic catalysts that do not contain sulfuric acid can be used as well to promote the acetylation reaction. In the case of sulfuric acid, at least some hydroxyl groups in the cellulose can be first functionalized as sulfate esters during the acetylation reaction. In general, most of such sulfate esters are cleaved during the controlled partial hydrolysis used to reduce the amount of acetyl substitution. In the case of other acidic catalysts, the probability of themselves reacting with cellulose hydroxyl groups is generally quite low.

  [0040] One of the highly desirable properties of acetylated cellulose is several different, depending on its intended end use, including, for example, films, flakes, fibers (eg, fiber tows), non-deformable solids, etc. The form can be easily processed. In most cases, acetylated cellulose obtained from controlled partial hydrolysis precipitates as a flaky material.

  [0041] To form a filament from cellulose acetate, a dope is formed as described above. The dope comprises one or more cabinets, each cabinet can be spun in a spinner with a spinneret. The spinneret comprises pores that affect the rate at which solvent evaporates from the filament. The pore shape and spinning parameters can be selected such that filaments having a selected size, cross-sectional shape, strength, and processability are formed. In general, the holes allow the formation of filaments with a diameter of 25-75 micrometers. Various designs for the holes are disclosed in US Patent Publication No. 2013/0192613, which is incorporated herein by reference in its entirety.

  [0042] The spinneret can be in a cabinet that operates at temperatures up to 100 ° C., but heat can be supplied by hot steam to evaporate the solvent. Over 90% of the solvent evaporates during the spinning process, leaving a solid filament of cellulose acetate. Filaments are generally in the range of 1 to 15 denier per filament and may have a cross-sectional shape including, but not limited to, circular, rugged, Y-shaped, X-shaped, and dogbone shapes. By modifying the temperature during the spinning process, as well as modifying the number of cabinets in the spinner, the strength of the filament can be adjusted. For example, when the filament first passes through the spinneret, the filament can be easily damaged or broken. However, as the filament moves further out of the spinneret, the filament hardens, the filament strength increases, and it is possible to evaporate the solvent by continuing stronger and more airflow. The air flow through the spinner may be cocurrent or countercurrent.

  [0043] As the filament passes through the spinneret, it is fed onto a constant speed roll where it can be further stretched. Additional spinning techniques can also be used in place of the dry spinning described herein, including wet spinning and melt spinning. Optionally, a lubricant or finish can be added to the filament. Exemplary lubricants or finishes include mineral oils, emulsifiers, and water as disclosed in US Pat. No. 7,585,442, which is incorporated herein by reference in its entirety. However, the lubricant or finish is not limited to these components. Lubricants or finishes can be applied by spraying or wiping. Generally, the lubricant or finish is added to the filaments before forming the filaments into the tow.

  [0044] The filaments are then bundled on a roller to form a tow. Generally, the tow can be a total denier in the range of 10,000 to 100,000 and can have a width of less than 8 cm (when measured from the horizontal end to the horizontal end). Once the tows are bundled, the tows can be plasticized before or during crimping. The plasticizer is generally liquid and sprayed on the tow, but other methods of applying the plasticizer are also available. A plasticizer is selected that acts as a binder or curing agent for cellulose acetate. A great variety of plasticizers are available in amounts of 2-40% by weight. The amount of plasticizer used depends on the plasticizer itself, as well as the desired hardness of the tow to be plasticized.

  [0045] In some preferred embodiments, the plasticizer is water, but numerous other plasticizers may be utilized. Suitable plasticizers for use with the plasticized cellulose acetate described herein include, in some embodiments, but are not limited to the following.

(Wherein, R1 is, _H, alkyl of C 1 -C _4, aryl, or alkylaryl of _C 1 -C ₄₎ wherein; wherein 2 (wherein, R2 is, _H, of C 1 -C ₄ alkyl, aryl, or alkylaryl of _C 1 -C _4, R3 is, _H, C 1 -C4 alkyl, _aryl, of C 1 -C ₄ alkylaryl, acyl, or alkyl acyl of _C 1 -C ₄ in a); wherein 3 (wherein, R4 and R6 are independently _H, alkyl of C 1 -C _{4, aryl,} alkyl aryl C 1 -C _{4, COOH,} alkyl carboxylate of C 1 -C _4, Acyl, C ₁ -C ₄ alkyl acyl, amine, C ₁ -C ₄ alkyl amine, amide, or C ₁ -C ₄ alkyl amide, R 5 is H, C ₁ -C ₄ alkyl, aryl , a of _C 1 _{~C 4} Kiruariru, acyl, or alkyl acyl of _C 1 -C _4); wherein 4 (wherein, R7 is, _H, alkyl of C 1 -C _{4, aryl,} alkyl aryl C 1 -C _4, OH, C ₁ -C ₄ alkoxy, alkyl amines amines, or _C 1 -C _4, R8 and R9 are independently _H, alkyl of C 1 -C _{4, aryl,} alkyl aryl C 1 -C _4, COOH C ₁ -C ₄ alkyl carboxylate, acyl, C ₁ -C ₄ alkyl acyl, amine, C ₁ -C ₄ alkyl amine, amide, or C ₁ -C ₄ alkyl amide); Formula 5 (wherein, R10, R11, and R12 are independently _H, alkyl of C 1 -C _{4, aryl,} alkyl aryl C 1 -C _{4, COOH,} alkyl carboxylate of C 1 -C ₄ , _Acyl, C 1 -C ₄ alkyl acyl, _amine, alkylamine of C 1 -C _4, amides, or alkyl amides of _C 1 _{~C 4);} Equation 6 (wherein, R13 is, H, C alkyl of ₁ -C _4, aryl, or alkylaryl of _C 1 -C _4, R14 and R16 are independently _H, alkyl of C 1 -C _{4, aryl,} alkyl aryl C 1 -C _4, COOH C ₁ -C ₄ alkyl carboxylate, acyl, C ₁ -C ₄ alkyl acyl, amine, C ₁ -C ₄ alkyl amine, amide, or C ₁ -C ₄ alkyl amide, and R 15 is H, C ₁ -C ₄ alkyl, aryl, C ₁ -C ₄ alkyl aryl, acyl, or C ₁ -C ₄ alkyl acyl; Formula 7 wherein R 17 is H or C _1- C An alkyl, R18, R19, R20 are independently _H, alkyl of C 1 -C _{4, aryl,} C 1 -C ₄ alkyl aryl, _COOH, alkyl carboxylate of C 1 -C _4, an acyl, C _{1 to} C ₄ alkyl acyl, amine, C _{1 to} C ₄ alkyl amine, amide, or C _{1 to} C ₄ alkyl amide); wherein R 21 is H, C _{1 to} C ₄ alkyl, _aryl, alkyl aryl C 1 -C _{4, COOH,} alkyl carboxylate of C 1 -C _4, an _acyl, alkyl acyl of C 1 -C _4, an _amine, alkylamine of C 1 -C _4, amides, or alkyl amides of _C 1 -C _4, R22 is, _H, alkyl of C 1 -C _{4, aryl,} alkyl aryl C 1 -C _4, an _acyl, a C 1 -C ₄ Rukiruashiru, amine, or _C 1 alkyl amines -C _4); wherein 9 (wherein, R23 and R24 are independently _H, alkyl of C 1 -C _{4, aryl,} alkyl aryl C 1 -C ₄ , _COOH, alkyl carboxylate of C 1 -C _4, an _acyl, alkyl acyl of C 1 -C _4, an _amine, alkylamine of C 1 -C _4, amides or alkyl amides of _C 1 _{~C 4);} wherein 10 (wherein, R25, R26, R27, and R28 are independently _H, alkyl of C 1 -C _{4, aryl,} alkyl aryl C 1 -C _{4, COOH,} alkyl carboxylate of C 1 -C ₄ , Acyl, C ₁ -C ₄ alkyl acyl, amine, C ₁ -C ₄ alkyl amine, amide, or C ₁ -C ₄ alkyl amide); 29, R30, and R31 are independently _H, alkyl of C 1 -C _{4, aryl,} alkyl aryl _{C 1 ~C 4, COOH, C} 1 ~C 4 alkyl carboxylates, _acyl, C 1 -C ₄ alkyl acyl, _amine, alkylamine of C 1 -C ₄ a, amides or alkyl amides of _C 1 _{~C 4);} wherein 12 (wherein, R32 is, _H, alkyl of C 1 -C _4, aryl , C ₁ -C ₄ alkylaryl, R 33 is H, C ₁ -C ₄ alkyl, aryl, C ₁ -C ₄ alkylaryl, OH, C ₁ -C ₄ alkoxy, acyl, C ₁ -C ₄ alkyl acyl, amine, or an alkyl amine of _{C 1 ~C 4, R34, R35} , and R36 are, _{H independently} alkyl of C 1 -C _{4, aryl,} a C 1 -C ₄ Rukiruariru, _COOH, alkyl carboxylate of C 1 -C _4, an _acyl, alkyl acyl of C 1 -C _4, an _amine, alkylamine of C 1 -C _4, amides or alkyl amides of _C 1 -C ₄₎ ; wherein 12 (wherein, R37, R38, R39, and R40 are independently _H, alkyl of C 1 -C _{4, aryl,} C 1 -C ₄ alkyl aryl, _COOH, alkyl carboxy of C 1 -C ₄ rate, _acyl, C 1 -C ₄ alkyl acyl, _amine, alkylamine of C 1 -C _4, amides, or alkyl amides of _C 1 _{~C 4);} wherein 14 (wherein, R41 is, H, C ₁ -C ₄ alkyl, _aryl, C 1 -C ₄ alkylaryl, OH, or alkoxy of _C 1 -C _4, R42 and R43 are, H are independently, _{C 1} Alkyl -C _{4, aryl,} alkyl aryl C 1 -C _{4, COOH,} alkyl carboxylate of C 1 -C _4, an _acyl, alkyl acyl of C 1 -C _4, an _amine, alkylamine of C 1 -C ₄ , Amide, or C ₁ -C ₄ alkylamide); independently H, C ₁ -C ₄ alkyl, aryl, C ₁ -C ₄ alkyl aryl, COOH, C ₁ -C ₄ alkyl carboxylate , Acyl, C ₁ -C ₄ alkyl acyl, amine, C ₁ -C ₄ alkyl amine, amide, or C ₁ -C ₄ alkyl amide, each derived from a cyclic carbon or cyclic nitrogen Group-containing triazines (1, 2, 3, 1, 2, 4, or 1, 3, 5); independently H, C ₁ -C ₄ alkyl, aryl, C ₁ -C ₄ alkyl aryl A ring that is C ₁ -C ₄ alkyl carboxylate, acyl, C ₁ -C ₄ alkyl acyl, amine, C ₁ -C ₄ alkyl amine, amide, or C ₁ -C ₄ alkyl amide Triazoles (1, 2, 3 or 1, 2, 4) having R substituents derived from each of formula carbon or cyclic nitrogen; independently H, C ₁ -C ₄ alkyl, aryl, C ₁ -C ₄ alkylaryl, _OH, C 1 -C ₄ alkoxy, _COOH, alkyl carboxylate of C 1 -C _4, an _acyl, C 1 -C ₄ alkyl acyl, _amine, alkylamine of C 1 -C _4, amides, or pyrrole having a C ₁ -C alkyl amides of _tetracyclic R substituent from each carbon or annular type nitrogen; independently H, alkyl of C ₁ -C _4, aryl, ₁ -C ₄ alkylaryl, _OH, alkoxy of C 1 -C _{4, COOH,} alkyl carboxylate of C 1 -C _4, an _acyl, alkyl acyl of C 1 -C _{4, amine,} alkyl of C 1 -C ₄ Piperidine having R substituents derived from each of a cyclic carbon or cyclic nitrogen that is an amine, amide, or C ₁ -C ₄ alkylamide; independently H, C ₁ -C ₄ alkyl, aryl, C ₁ -C ₄ alkylaryl, _OH, alkoxy of C 1 -C _{4, COOH,} alkyl carboxylate of C 1 -C _4, an _acyl, alkyl acyl of C 1 -C _4, an _amine, alkylamine of C 1 -C ₄ , amide, or _C 1 -C piperazine with R substituent from each cyclic carbon or cyclic nitrogen is an alkylamide of _4; R44 and R46 Independently _H, alkyl of C 1 -C _{4, aryl,} alkyl aryl C 1 -C _{4, COOH,} alkyl carboxylate of C 1 -C _4, an _acyl, alkyl acyl of C 1 -C _4, amine, C alkylamines ₁ -C _4, an amide, or an alkylamide _C 1 -C _4, and R45 _is, R44HN-R45-NHR46 alkyl of C 1 _{-C 10;} and combinations thereof. As used herein, “alkyl” means a substituent having C and H that may be linear or branched (eg, t-butyl) and saturated or unsaturated. As used herein, “aryl” means an aromatic ring that may include phenyl, naphthyl, and aromatic rings containing heteroatoms.

[0046] As examples of plasticizers suitable for use in the plasticized cellulose acetate described herein, in some embodiments, triacetin, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, triethyl Citrate, acetyl trimethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, tributyl-o-acetyl citrate, dibutyl phthalate, diaryl phthalate, diethyl phthalate, dimethyl phthalate, di-2-methoxyethyl phthalate, dioctyl phthalate (and Isomers), dibutyl tartrate, ethyl-o-benzoylbenzoate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, n-ethyl t Ensulfonamide, o-cresyl-p-toluenesulfonate, aromatic diol, substituted aromatic diol, aromatic ether, tripropionine, tribenzoin, polycaprolactone, glycerin, glycerin ester, diacetin, glycerol tribenzoate, glycerol acetate benzoate , Polyethylene glycol, polyethylene glycol ester, polyethylene glycol diester, di-2-ethylhexyl polyethylene glycol ester, glycerol ester, diethylene glycol, polypropylene glycol, polyglycol diglycidyl ether, dimethyl sulfoxide, N-methylpyrrolidinone, propylene carbonate, C ₁ dicarboxylic acid of ~C ₂₀ Este , Dimethyl adipate (and other dialkyl esters), dibutyl malate, dioctyl malate, resorcinol monoacetate, catechol, catechol ester, phenol, epoxidized soybean oil, castor oil, linseed oil, epoxidized linseed oil, other vegetable oils, etc. Seed oils, bifunctional glycidyl ethers based on polyethylene glycol, alkyl lactones (eg γ-valerolactone), alkyl phosphate esters, aryl phosphate esters, phospholipids, fragrances (some described herein, eg eugenol , Cinnamyl alcohol, camphor, methoxyhydroxyacetophenone (acetovanillone), vanillin, and ethyl vanillin), 2-phenoxyethanol, glycol ether, glycol Stealth, glycol ester ether, polyglycol ether, polyglycol ester, ethylene glycol ether, propylene glycol ether, ethylene glycol ester (eg, ethylene glycol diacetate), propylene glycol ester, polypropylene glycol ester, acetylsalicylic acid, acetaminophen, Naproxen, imidazole, triethanolamine, benzoic acid, benzylbenzoate, salicylic acid, 4-hydroxybenzoic acid, propyl-4-hydroxybenzoate, methyl-4-hydroxybenzoate, ethyl-4-hydroxybenzoate, benzyl-4-hydroxybenzoate, Glyceryl tribenzoate, neopentyl dibenzoate, triethylene glycol di Nzoate, trimethylolethane tribenzoate, butylated hydroxytoluene, butylated hydroxyanisole, sorbitol, xylitol, ethylenediamine, piperidine, piperazine, hexamethylenediamine, triazine, triazole, pyrrole, etc., any derivative thereof, and any combination thereof However, it is not limited to these.

[0047] Examples of additional plasticizers suitable for use in the plasticized cellulose acetate described herein may include, in some embodiments, nonionic surfactants, which may include Are polysorbates (eg TWEEN® 20 or TWEEN® 80 available from SigmaAldrich), sorbitan esters (eg SPAN® products available from SigmaAldrich), polyethoxylated aromatics Hydrocarbons (eg, TORITON® products available from SigmaAldrich), polyethoxylated fatty acids, polyethoxylated fatty alcohols (eg, BRIJ® products available from SigmaAldrich), fluorine-based interfaces tail of the active agent, glucoside and hydrocarbons, _(e.g., C 6 _{-C 22} alkyl group)及And other nonionic surfactants having hydrophilic head groups including hydroxyl groups and ester groups, and combinations thereof, but are not limited thereto. Some nonionic surfactants have been discovered to plasticize cellulose acetate, either alone or in combination with small molecule plasticizers. This is surprising because conventional plasticizers are small molecules. In contrast, nonionic surfactants with long hydrocarbon tail groups and possibly large head groups are bulky. For example, polyoxyethylene (20) sorbitan monolaurate is significantly larger than conventional cellulose acetate plasticizers such as triacetin, but has been found to plasticize cellulose acetate.

  [0048] In some embodiments, the plasticizer may be biologically derived. For example, biologically derived triacetin, diacetin, tripropionine, glyceryl esters can be produced from glycerol, a byproduct of biodiesel. Other examples of plasticizers that may be biologically derived include vanillin, acetovanillone, γ-valerolactone, eugenol, epoxidized soybean oil, castor oil, linseed oil, epoxidized linseed oil, and dicarboxylate esters (eg, dimethyl adipate, dibutyl Malate), but is not limited thereto. In some cases, the aromatic plasticizer can be extracted from natural products and is therefore a biological plasticizer.

  [0049] In some embodiments, the plasticizer can be a semi-volatile to volatile plasticizer. Examples of some preferred semi-volatile to volatile plasticizers include glycerol esters (eg, triacetin, diacetin, monoacetin), ethylene glycol diacetate, alkyl lactones (eg, γ-valerolactone), dibutyl malate, dioctyl Examples include, but are not limited to, malate, dibutyl tartrate, eugenol, tributyl phosphate, tributyl-o-acetyl citrate, and resorcinol monoacetate.

  [0050] In some embodiments, two or more plasticizers can be utilized. Furthermore, thermoplastic polymers can be included with the tow during the plasticization step. Thermoplastic polymers include polyolefins (eg, polyethylene and polypropylene), polyalphaolefins, polyesters, ethylene vinyl acetate copolymers, polyvinyl acetate, polyvinyl alcohol (“PVOH”), polyethylene imines, polyacrylates, polymethacrylates, polyacrylamides, poly Acrylonitrile, polyimide, polyamide, polyvinyl chloride, polysiloxane, polyurethane, polystyrene, polyetheramide copolymer, styrene-butadiene copolymer, styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene-butylene-styrene copolymer, Styrene-ethylene-propylene-styrene copolymer, butyl rubber, poly Isobutylene, isobutylene - isoprene copolymers, acrylics, nitriles, and combinations thereof.

  [0051] Once the tow is plasticized, it is directed to the crimper. In some embodiments, the tow is plasticized at least 0.5 meters before entering the crimper, such as at least 1 meter. Alternatively, the tow can be plasticized in the crimper. A large number of crimpers are known in the art, but they generally operate by drawing the tow into the crimper, in which case a roller with some groove or surface texture guides the crimp to the tow . A crimper is a stuffer box having a base frame and a top frame that moves relative to the base frame, as described in US Pat. No. 7,585,442, which is hereby incorporated by reference in its entirety. Can be a crimper. The crimper comprises a nip roller, a cheek plate on the side of the nip roller, a doctor blade, a flapper, and a steam injector.

  [0052] The tow is pulled through the crimper by a pair of nip rollers, but the nip roller is called a “crimp induction” roller because it creases or bends as the tow passes through the nip. In some cases, thus affecting the location of the crimp in the tow. Of the pair of nip rollers, one nip roller may be smooth, but the other nip roller may be provided with a groove. The grooves can be of any type including surface texture, such as grooves, recesses, or other types of textures. The grooves are preferably in the form of a sine curve, but may be rectangular, triangular, or semi-circular cutouts, grooves, or ridges, with an axis across the surface of the roller between the grooves. There may or may not be a flat surface extending in the direction of (i.e., horizontal to horizontal). These grooves are in the range of 10-100 per 2.5 cm (1 inch), preferably 25-75 per 2.5 cm (1 inch), most preferably per 2.5 cm (1 inch). There may be 50 grooves. Groove depth (peak to trough) can range from 12.5 microns to 150 microns (0.5 mil to 5.0 mils), preferably 25 to 50 microns (1 to 2 mils).

  [0053] Each nip roller includes steel / alloy bonded titanium carbide, tungsten carbide, HIP treated or not HIP treated MgO stabilized zirconia, or HIP treated or not HIP treated yttria stabilized zirconia, but these It can be made of a metal material or a ceramic material that is not limited thereto. In some embodiments, the upper nip roller is smooth while the lower nip roller is grooved. The tow leaves the nip roller and enters the stuffer box. In some embodiments, the end of the tow is lubricated before entering the stuffer box to minimize filament damage between the nip roller and the cheek plate located on the side of the nip roller. Can be This cheek plate can serve as a guide to maintain the tow between nip rollers. The doctor blade is located adjacent to the nip roller and serves to guide the tow to the stuffer box and prevent the tow from sticking to the roller.

  [0054] The stuffer box comprises a steam injector located adjacent to the nip roller in each side of the stuffer box. A steam injector injects steam, typically low pressure dry steam at a temperature of about 100 ° C., into the stuffer box to secure and lightly couple the tow crimp in the channel of the stuffer box.

  [0055] The shape of the crimp may play a role in the processability of the final bale. Examples of crimp shapes can include horizontal, substantially horizontal, vertical, substantially vertical, an angle between horizontal and vertical, random, or any combination thereof. It is not limited to these. It should be noted that the terms “horizontal” and “vertical” generally refer to the overall crimp orientation, which may deviate +/− about 30 degrees from the shape.

  [0056] The shape of the crimp can also be important for the processability of the final bale in subsequent process steps, for example, horizontally and / or substantially if no further steps are taken to enhance the cohesive strength. A horizontal crimp shape can achieve better filament cohesion than a vertical and / or substantially vertical crimp shape. In order to achieve a horizontal crimp, at least one of three processing parameters, for example, the moisture content of the tow before crimping, the thickness of the tow during crimping, and the ratio of the nip force to the flap force during crimping is Can be manipulated.

  [0057] In order to achieve a horizontal and / or substantially horizontal crimp shape, crimping is performed on a tow containing a low percentage by weight of total moisture, such as 5-25% filaments. It is considered desirable. In some embodiments, the lower moisture weight percent is controlled by drying the tow prior to crimping, applying a higher solids concentration or lower water content finish emulsion, or applying a fine finish after applying a fine finish. Adding spinning water, reducing or eliminating any other moisture-related tow additions, and changing spinning conditions to reduce the moisture content of the fibers leaving the spinning cell Increase, decrease the speed, increase the airflow in the heating cabinet, change the dope concentration), or any combination thereof.

  [0058] Further, a horizontal and / or substantially horizontal crimp shape is achieved by crimping a narrow tow, ie by reducing the total denier per 2.5 cm (1 inch) of crimper nip roller width. obtain. In some embodiments, the total denier per inch of crimper nip roller width can be about 60,000 or less, about 50,000 or less, or about 40,000 or less. Suitable crimper nip roller widths per 2.5 cm (1 inch) of denier are from a lower limit of about 5,000, 10,000, 15,000, or 20,000 to an upper limit of 60,000, 50,000, 40,000. , 35,000, or 30,000, but the total denier per crimper nip roller width 2.5 cm (1 inch) can range from any of the lower limits to any of the upper limits. , Any subset in between.

  [0059] Further, a horizontal and / or substantially horizontal crimp shape is achieved by crimping with a reduced ratio of nip force to flap force, ie, a ratio of applied nip force to applied flap force. obtain. In some embodiments, the ratio of nip force to flap force can be about 100: 1 or less, about 50: 1 or less, or about 25: 1 or less. The ratio of nip force to suitable flap force can range from a lower limit of about 3: 1, 5: 1, or 10: 1 to an upper limit of about 100: 1, 50: 1, or 25: 1, where The nip to flap ratio can range from any of the lower limits to any of the upper limits and can include any subset in between.

  [0060] It should be noted that at least two of the above methods of achieving a horizontal and / or substantially horizontal crimp shape can be used in any combination. It should also be noted that when used in combination, the limit values for the above parameters can be extended, since the combined use can produce a synergistic effect. As a non-limiting example, a tow with a moisture of about 27% w / w has a nip force to flap force ratio of about 15: 1 and a total denier of about 25,000 per 2.5 cm (1 inch) of crimper nip roll width. Crimping can result in a horizontal and / or substantially horizontal crimp shape.

  [0061] Once the crimp is formed, the tow is directed to a dryer that dries and removes residual water and / or acetone. The dried tow is then fed to the can to form a tow stack. The dried tow can be placed in the can by a series of rollers, for example in a pattern with the tows placed side-by-side, stacked or aligned. It should be noted that cans can be used to refer generally to containers of any shape, preferably square or rectangular, and any material. The term “pattern” means any design and may or may not change during placement. In some embodiments, the pattern is substantially zigzag having a periodicity of about 1.6 cycles / m to about 19.7 cycles / m (about 0.5 cycles / ft to about 6 cycles / ft). It can be. In some embodiments, the positioning step can include paddling the tow using a paddling index of about 10 m / m to about 40 m / m. The term “paddling” means that when the tow is placed, the tow is placed at least partially horizontally on it such that the actual length of the tow is greater than its linear distance. The term “paddling index” means how many times the length of the tow corresponds to the linear distance when the tow is placed.

  [0062] The tow stack then moves to a bale press where the bale is compressed and packaged for shipping. The can is set in the press wall and then compressed by the platen. An exemplary tow bale compression and bale press design is disclosed in US Pat. No. 7,610,852, which is incorporated herein by reference in its entirety. In general, bale presses include two shaped platens that are selected to allow formation on a tow having a substantially flat surface that is maintained until packaging. Such a substantially flat surface is advantageous because the bale can be stacked during storage and shipping. In addition, a flat surface on the bale is advantageous in the debaling process described herein because the tow is less likely to become entangled and debaying can be accomplished more efficiently.

  [0063] In some embodiments, the packaging may include at least one component, such as a wrapping material, a vacuum port (for vacuum release and / or vacuum suction), a fastening element, or any combination thereof. Suitable wrapping materials include air permeable materials, air impermeable materials, films (eg, polymer films, polyethylene films, plastic wrap), heat shrinkable films, cardboard, wood, woven materials (ie, to form fabrics) Fabrics composed of two sets of interlaced yarns), non-woven materials (ie, random web or matte textile fiber assemblies, eg fused, held together by mechanical or chemical means) Thermoplastic fibers), foil materials (eg, metal materials), etc., or any combination thereof, but is not limited to these. Suitable fastening elements include VELCRO®, pins, hooks, straps (eg, woven, non-woven, fabric, and / or metal), adhesives, tapes, melt binders, etc., or any combination thereof However, it is not limited to these. In some embodiments, at least a portion of the package (including any of its components) can be reusable.

[0064] In some embodiments, the bale has a height from about 76 cm (30 inches) to about 152 cm (60 inches), a length from about 117 cm (46 inches) to about 142 cm (56 inches), and a width It may have dimensions in the range of about 89 cm (35 inches) to about 114 cm (45 inches). In some embodiments, the bale ranges from 408 kg (900 lbs) to 953 kg (2100 lbs). In some embodiments, the bale may have a density greater than about 300 kg / m ³ (18.8 lb / ft ³ ).

  [0065] The invention will be better understood with reference to the following non-limiting examples.

  V. Example

  [0066] A slurry was prepared containing 59.82 wt% titanium dioxide, 39.52 wt% water, and 0.66 wt% additive. Titanium dioxide was treated with an organic material and coated with an inorganic coating. The slurry was then stored in a container at ambient temperature (about 25 ° C.). The particle size distribution was measured using a Mastersizer 2000 particle sizer sold by Malvern Instruments. Measurements were taken after 1 day storage and 18 days storage. The results are shown in Table 1 below.

  [0067] As shown in Table 1, the increase in the particle size distribution of the slurry is acceptable over 18 days, based on both distribution measurement methods, the particle size is less than 1 μm, and the percent increase from the first day Was less than 20%.

  [0068] Slurries were prepared as in Example 1 and measured after storage for 1 day, 8 days, and 22 days. The particle size distribution was measured in the same manner as in Example 1. The results are shown in Table 2 below.

  [0069] As shown in Table 2, the increase in the particle size distribution of the slurry is acceptable over 8 and 22 days, and based on both distribution measurement methods, the particle size is less than 1 μm, starting from day 1. The percent increase in was less than 20%.

  [0070] A slurry was prepared as in Example 1, except that titanium dioxide was coated with a different organic coating agent. The particle size distribution was measured in the same manner as in Example 1. The results are shown in Table 3 below.

  [0071] As shown in Table 3, the particle size distribution of the slurry increased by more than 20% from day 1 to day 4 and from day 1 to day 12, based on both distribution measurement methods. When the slurry of Example 3 is used with a cellulose acetate dope after storage, it must be pumped through a particle size reduction device to reduce the particle size distribution so that further aggregation does not increase the particle size distribution again. To be thorough, it would have to be used in a short time after such a reduction in particle size.

  [0072] A slurry was prepared as in Example 1. The slurry was then directed to a sand mill where the slurry was pumped through the mill at a rate of about 4.5-5.4 kg / min (10-12 lb / min). After pulverization, the particle size distribution of the pulverized slurry was measured. A comparison of the unmilled and milled slurry compositions is shown in Table 4 below. An unmilled slurry sample was collected immediately before the sand mill, and a ground sample was collected immediately after the sand mill. Once the slurry was initially dispersed in water and other additives, the unmilled sample was collected from the bottom of the high shear mixer tank just prior to being pumped through the sand mill. Each of the ungrinded and crushed samples were collected and measured within 24 hours. In the same manner as in Example 1, the particle size distribution was measured.

[0073] As mentioned above, even though the slurry had D [4,3] and D [0.9] particle size distributions of less than 1 μm, the grinding treatment was beneficial in reducing the particle size. .
[0074] Although the invention has been described in detail, modifications within the spirit and scope of the invention will be apparent to those skilled in the art. Aspects of the present invention and portions of various embodiments, and various features within the above-listed and / or appended claims, may be combined or interchanged in whole or in part. It should be understood that there is. As those skilled in the art will appreciate in the foregoing description of various embodiments, an embodiment that refers to another embodiment can be appropriately combined with other embodiments. Further, those skilled in the art will recognize that the above description is limited to illustrative purposes and is not intended to limit the invention.

Claims (21)

  A slurry comprising 30-60 wt% titanium dioxide, 39-69 wt% water, and 0.1-1 wt% one or more additives, based on the total weight of the slurry, at ambient temperature A slurry having a D [4,3] and D [0.9] particle size distribution of less than 1 μm after storage for 4 days.   The slurry of claim 1 having a D [4,3] and D [0.9] particle size distribution of less than 1 μm after storage at ambient temperature for 8 days.   The slurry of claim 1 having a D [4,3] and D [0.9] particle size distribution of less than 1 μm after 18 days storage at ambient temperature.   The slurry according to claim 1, wherein the one or more additives are selected from the group consisting of a dispersant, an antibacterial agent, and combinations thereof.   The slurry of claim 1 wherein the titanium dioxide is food grade titanium dioxide.   The slurry of claim 1, wherein the titanium dioxide is coated with an inorganic coating.   7. The slurry according to claim 6, wherein the inorganic coating is an oxide or hydroxide of at least one element selected from the group consisting of aluminum, cerium, magnesium, silicon, titanium, zinc, and zirconium. Slurry.   The slurry according to claim 1, wherein titanium dioxide is treated with an organic substance.   9. The slurry of claim 8, wherein the organic material comprises liquid and solid polyols, liquid polyphosphates, liquid hydroxyamines, liquid and solid styrene-maleic anhydride copolymers, and combinations thereof. A slurry selected from the group.   9. The slurry of claim 8, wherein the organic material is a low molecular weight polyglycol, trimethylolpropane, triethanolamine, 2-amino-2-methyl-1-propanol, tetrapotassium pyrophosphate, and combinations thereof. A slurry selected from the group consisting of:   The slurry of claim 1, wherein the increase in D [4,3] and D [0.9] particle size distribution is less than 20% when stored at ambient temperature for 4 days.   A slurry comprising 10-25 wt% titanium dioxide, 65-85 wt% acetone, and 5-10 wt% one or more additives, based on the total weight of the slurry, for 4 days at ambient temperature A slurry having a D [4,3] and D [0.9] particle size distribution of less than 1 μm after storage.   13. The slurry of claim 12, wherein the one or more additives include a viscosity modifier. A method for preparing a slurry comprising the steps of:
Combining titanium dioxide, liquid, and at least one additive to form a slurry;
Mixing the slurry and pumping the slurry through a particle size reduction device, wherein the slurry is stored at ambient temperature for 4 days and then less than 1 μm of D [4,3] and D [0.9] A method having a particle size distribution.   15. The method of claim 14, wherein the particle size reduction device is selected from the group consisting of a pebble mill, a sand mill, a high shear pump, and a premix dispenser.   15. The method of claim 14, wherein the slurry has a D [4,3] and D [0.9] particle size distribution of less than 1 [mu] m after 8 days storage at ambient temperature.   15. The method of claim 14, wherein the slurry has a D [4,3] and D [0.9] particle size distribution of less than 1 [mu] m after 18 days storage at ambient temperature. A method for preparing a cellulose acetate dope comprising the steps of:
A slurry comprising titanium dioxide, a liquid, and at least one additive is prepared, wherein the slurry is stored at ambient temperature for 18 days and then has a D [4,3] and D [0.9 of less than 1 μm. ] Having a particle size distribution;
Mixing the slurry with cellulose acetate and a solvent to dissolve the cellulose acetate in an outer solvent, dispersing the slurry; and filtering the cellulose acetate dope to remove solvent insoluble particles;
The cellulose acetate dope comprises, based on the total weight of the dope, 20-30 wt% cellulose acetate, 70-80 wt% solvent, and 0.05-3 wt% titanium dioxide;
Furthermore, a process wherein less than 1% by weight of titanium dioxide is removed during filtering.   19. The method of claim 18, wherein the slurry is 10-25 wt% titanium dioxide, 65-85 wt% acetone, and 5-10 wt% one or more based on the total weight of the slurry. A method comprising an additive.   19. The method of claim 18, wherein the slurry is 30-60% titanium dioxide, 39-69% water, and 0.1-1% by weight based on the total weight of the slurry. Or a method comprising a plurality of additives.   19. The method of claim 18, wherein the solvent is selected from the group consisting of water, acetone, methyl ethyl ketone, methylene chloride, dioxane, dimethylformamide, methanol, ethanol, glacial acetic acid, supercritical carbon dioxide, and combinations thereof. Method.