Dry spinning of cellulose acetate fibers.

Abstract

A dry spinning system and method is used to produce cellulose ester fibers. The method utilizes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, or mixtures thereof as a dissolving solvent. The method minimizes or avoids discoloration of the fibers.

Description

[Technical field]

[0001] FIELD OF THEINVENTION This application relates generally to the spinning of fibers. More specifically, this application relates generally to the dry spinning of cellulose esters into fibers. [Background technology]

[0002] 2. Background of the Invention Cellulose acetate fibers are traditionally dry spun using acetone as the spinning solvent. As the filament market has grown, there has been a need to increase spinning capacity, but adding new production lines is very expensive when considering the need for solvent recovery, capital investment, etc. A cost-effective alternative is to use vacant dry spinning capacity available in the acrylic and urethane fiber markets. However, these techniques involve the use of DMF (N,N-dimethylformamide) or DMAc (N,N-dimethylacetamide) as the solvent. DMF is a very effective solvent, but due to its high boiling point, it requires much higher operating temperatures than acetone. These higher operating temperatures can cause degradation of the cellulose acetate and / or DMF, resulting in unacceptable yellowing of the fibers. Thus, there is a need for a dry spinning process using DMF that results in less color formation. Summary of the Invention

[0003] Summary of the Invention The present disclosure provides a method for producing a cellulose ester fiber, the method comprising dry spinning a cellulose ester dope through a spinneret to produce one or more fibers. The cellulose ester dope comprises at least 35% by weight, on a solids basis, of a cellulose ester dissolved or dispersed in a solvent selected from N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, or mixtures thereof. When the solvent comprises N,N-dimethylacetamide, (i) the cellulose ester dope contains 50% by weight or less of acetone based on the total weight of the cellulose ester dope; or (ii) the cellulose ester dope contains 0% by weight cellulose nanocrystals, or (iii) Both (i) and (ii). The total weight of polyurethane, polyolefin, nylon, polyester and / or polyurethane urea that may be present in the cellulose ester dope is 60 weight percent or less, based on the total solids in the cellulose ester dope.

[0004] The present disclosure also provides a method of making a cellulose ester fiber, the method comprising dry spinning a cellulose ester dope through a spinneret to produce one or more fibers. The cellulose ester dope comprises a cellulose ester dissolved or dispersed in a solvent selected from N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, or mixtures thereof. When the solvent comprises N,N-dimethylacetamide, (i) the cellulose ester dope contains 50% by weight or less of acetone based on the total weight of the cellulose ester dope; or (ii) the cellulose ester dope contains 0% by weight cellulose nanocrystals, or (iii) Both (i) and (ii). The cellulose ester dope contains up to 10% by weight of polyurethane and up to 50% by weight of acrylonitrile-vinyl acetate copolymer, both based on the total solids in the cellulose ester dope. The total weight of polyurethane, polyolefin, nylon, polyester and / or polyurethane urea that may be present in the cellulose ester dope is up to 60% by weight, based on the total solids in the cellulose ester dope.

[0005] The present disclosure also provides cellulose ester fibers formed according to one or both of the above methods.

[0006] The present disclosure further provides yarns, articles, woven articles, nonwoven articles, staple fibers and / or knitted textiles comprising cellulose ester fibers formed according to one or both of the above processes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Detailed Description This application generally relates to a dry spinning process for preparing cellulose diacetate ("CDA") and / or cellulose triacetate ("CTA") fibers exhibiting low color development. Such fibers can be utilized to expand application opportunities in downstream fiber processing and end-use apparel applications. Moreover, such cellulose ester fibers can be produced using a dry spinning process, in which a cellulose ester is at least partially dissolved in a solvent (e.g., N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and mixtures thereof) and the resulting dope is extruded through small spinneret orifices into a spinning cabinet where the solvent flashes off.

[0008] At least one cellulose ester and at least one dissolving solvent can be introduced into the dope mixer to form a cellulose ester dope. The dope mixer can include any conventional device that can mix cellulose ester and dissolving solvent. An exemplary dope mixer can include a continuous stirred tank reactor ("CSTR"). In the dope mixer, the cellulose ester and solvent are exposed to temperature and mixing conditions that promote the dissolution of the cellulose ester into the dissolving solvent, thereby forming a cellulose ester dope.

[0009] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester dope can include a solids content of at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, at least 20%, at least 21%, at least 22%, or at least 23%, and / or 35% or less, 34% or less, 33% or less, 32% or less, 31% or less, 30% or less, 29% or less, or 28% or less by weight based on the total weight of the dope. For example, the cellulose ester dope may contain a solid content in the range of 15% by mass to 35% by mass, 16% by mass to 34% by mass, 17% by mass to 33% by mass, 17% by mass to 22% by mass, 18% by mass to 32% by mass, 19% by mass to 31% by mass, 20% by mass to 31% by mass, 21% by mass to 30% by mass, 22% by mass to 29% by mass, or 23% by mass to 28% by mass, based on the total mass of the dope.

[0010] The cellulose ester may include any cellulose ester known in the art, particularly those containing acetyl groups. The cellulose esters that can be used in the present invention generally contain repeat units of the following structure: [ka] (In the formula, R 1 , R 2 and R 3 are independently selected from the group consisting of hydrogen or straight chain alkanoyl having 2 to 10 carbon atoms. Exemplary alkanoyls include acetyl, propionyl, and / or butyryl.

[0011] In the case of cellulose esters, the substitution level is usually expressed as the degree of substitution ("DS"), which is the average number of non-OH substituents per anhydroglucose unit ("AGU"). Generally, conventional cellulose contains three hydroxyl groups that can be substituted on each AGU unit. Thus, the DS can range from 0 to 3. However, low molecular weight cellulose esters can have a total degree of substitution slightly greater than 3 due to the influence of end groups. Since the DS is a statistical average, a value of 1 does not guarantee that all AGUs have a single substituent. In some cases, there may be unsubstituted AGUs, some with two substituents, and some with three substituents. The "total DS" is defined as the average number of all substituents per AGU, and typically the value will be a non-integer. The degree of substitution per AGU can also refer to a specific substituent, such as hydroxyl, acetyl, butyryl, or propionyl.

[0012] In one embodiment, or in combination with any other mentioned embodiment, the cellulose ester comprises at least 1.5, at least 1.55, at least 1.6, at least 1.65, at least 1.7, at least 1.75, at least 1.8, at least 1.85, at least 1.9, at least 1.95, at least 2.0, at least 2.05, at least 2.1, at least 2.15, at least 2.2, at least 2.25, at least 2.3, at least 2.35, or at least 2.38, and / or a DS acetyl of 2.95 or less, 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, 2.55 or less, 2.5 or less, or 2.45 or less. In certain embodiments, the cellulose ester has a DS in the range of 2.6 to 2.95, 2.7 to 2.95, 1.5 to 2.6, 1.6 to 2.6, 1.7 to 2.6, 1.8 to 2.6, 1.9 to 2.6, 2.0 to 2.6, 2.05 to 2.6, 2.1 to 2.6, 2.15 to 2.6, 2.2 to 2.6, 2.25 to 2.55, 2.3 to 2.5, or 2.38 to 2.45. アセチル may include.

[0013] Additionally or alternatively, in one embodiment or in combination with other mentioned embodiments, the cellulose ester comprises at least 0.05, at least 0.1, at least 0.2, at least 0.3, at least 0.4, or at least 0.5, and / or 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, or 1.0 or less DSOH. In certain embodiments, the cellulose ester comprises a DSOH in the range of 0.05-1.5, 0.1-1.5, 0.2-1.4, 0.3-1.2, 0.4-1.1, or 0.5-1.0.

[0014] Additionally or alternatively, in one embodiment or in combination with other mentioned embodiments, the cellulose ester comprises a DS butyryl of at least 0.1, at least 0.2, or at least 0.3, and / or 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, or 0.4 or less. In certain embodiments, the cellulose ester comprises a DS butyryl of 0.1 to 1.5, 0.1 to 1.2, 0.1 to 0.8, 0.1 to 0.4, 0.2 to 1.5, 0.2 to 1.2, 0.2 to 0.8, 0.2 to 0.4, 0.3 to 1.5, 0.3 to 1.2, 0.3 to 0.8, or 0.3 to 0.6. ブチリル Includes.

[0015] Additionally or alternatively, in one embodiment or in combination with other mentioned embodiments, the cellulose ester comprises at least 0.1, at least 0.2, or at least 0.3, and / or 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, or 0.4 or less DS propionyl. In certain embodiments, the cellulose ester comprises 0.1 to 1.5, 0.1 to 1.2, 0.1 to 0.8, 0.1 to 0.4, 0.2 to 1.5, 0.2 to 1.2, 0.2 to 0.8, 0.2 to 0.4, 0.3 to 1.5, 0.3 to 1.2, 0.3 to 0.8, or 0.3 to 0.6 DS propionyl. プロピオニル Includes.

[0016] Additionally or alternatively, in one embodiment, or in combination with other mentioned embodiments, the cellulose ester comprises a total DS of at least 1.5, at least 1.55, at least 1.6, at least 1.65, at least 1.7, at least 1.75, at least 1.8, at least 1.85, at least 1.9, at least 1.95, at least 2.0, at least 2.05, at least 2.1, at least 2.15, at least 2.2, at least 2.25, at least 2.3, at least 2.35, or at least 2.38, and / or 2.95 or less, 2.9 or less, 2.85 or less, 2.8 or less, 2.75 or less, 2.7 or less, 2.65 or less, 2.6 or less, 2.55 or less, 2.5 or less, or 2.45 or less. In certain embodiments, the cellulose ester can comprise a total DS in the range of 1.5 to 2.95, 1.6 to 2.85, 1.7 to 2.8, 1.8 to 2.75, 1.9 to 2.7, 2.0 to 2.65, 2.05 to 2.6, 2.1 to 2.6, 2.15 to 2.6, 2.2 to 2.6, 2.25 to 2.55, 2.3 to 2.5, or 2.38 to 2.45.

[0017] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester can be cellulose diacetate and / or cellulose triacetate. Alternatively, in certain embodiments, the cellulose ester can include mixed cellulose esters, such as cellulose acetate butyrate or cellulose acetate propionate.

[0018] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester can have an acetyl content of at least 30%, at least 35%, or at least 40% by weight, and / or 62.5% or less, 60% or less, 55% or less, 50% or less, or 45% or less by weight, based on the total acetic acid weight percent. In certain embodiments, the cellulose ester can have an acetylation degree in the range of 30-62.5%, 35%-55%, 35%-50%, 35%-45%, 40%-62.5%, 40%-60%, 40%-55%, 40%-50%, or 40%-45% by weight.

[0019] Additionally or alternatively, in one embodiment, or in combination with other mentioned embodiments, the cellulose ester can have a hydroxyl content of at least 0.3%, at least 0.5%, at least 1%, at least 2%, at least 3%, or at least 4%, and / or 20% or less, 15% or less, 10% or less, or 5% or less by weight. In certain embodiments, the cellulose ester can have a hydroxyl content in the range of 0.3% to 20%, 0.5% to 20%, 2% to 15%, 3% to 10%, or 4% to 5% by weight.

[0020] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester can have a number average degree of polymerization of at least 100, at least 110, at least 120, at least 130, at least 140, at least 150, at least 160, at least 170, at least 180, at least 190, at least 200, at least 210, at least 220, at least 230, at least 240, at least 250, at least 260, or at least 265. Additionally or alternatively, in one embodiment or in combination with other mentioned embodiments, the cellulose ester has an average molecular weight of 1,000 or less, 900 or less, 800 or less, 700 or less, 600 or less, 500 or less, 400 or less, 350 or less, 325 or less, 300 or less, 290 or less, 280 or less, 270 or less, 260 or less, 250 or less, 240 or less, 230 or less, 220 or less, 210 or less, 200 or less, 190 or less, 180 or less, 170 or less, 160 or less, 150 or less, 149 or less, 148 or less , 147 or less, 146 or less, 145 or less, 144 or less, 143 or less, 142 or less, 141 or less, 140 or less, 139 or less, 138 or less, 137 or less, 136 or less, 135 or less, 134 or less, 133 or less, 132 or less, 131 or less, 130 or less, 129 or less, 128 or less, 127 or less, 126 or less, 125 or less, 124 or less, 123 or less, 122 or less, 121 or less, 120 or less, 119 or less, 118 or less, 117 or less, 116 or less, or 115 or less. In certain embodiments, the cellulose ester can have a number average degree of polymerization in the range of 100 to 1,000, 100 to 500, 100 to 400, 100 to 300, 100 to 250, 100 to 200, 100 to 150, 100 to 135, 100 to 200, 100 to 150, 100 to 135, 100 to 180, 100 to 150, 100 to 145, 100 to 140, 100 to 135, or 100 to 130.

[0021] In one embodiment, or in combination with any other mentioned embodiment, the cellulose ester can have a number average absolute molecular weight in daltons of at least 5,000 daltons, at least 10,000 daltons, at least 15,000 daltons, at least 20,000 daltons, or at least 25,000 daltons, and / or no more than 75,000 daltons, no more than 70,000 daltons, no more than 65,000 daltons, no more than 60,000 daltons, no more than 55,000 daltons, no more than 50,000 daltons, no more than 45,000 daltons, no more than 40,000 daltons, no more than 35,000 daltons, or no more than 30,000 daltons, as measured by gel permeation chromatography ("GPC") according to ASTM D6474. In certain embodiments, the cellulose ester can have a number average absolute molecular weight ranging from 5,000 daltons to 75,000 daltons, from 10,000 daltons to 65,000 daltons, or from 15,000 daltons to 35,000 daltons, as measured by GPC according to ASTM D6474.

[0022] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester may have a weight average absolute molecular weight of at least 50,000 daltons, at least 55,000 daltons, at least 60,000 daltons, at least 65,000 daltons, at least 70,000 daltons, at least 75,000 daltons, at least 80,000 daltons, or at least 85,000 daltons, and / or no more than 150,000 daltons, no more than 140,000 daltons, no more than 130,000 daltons, no more than 120,000 daltons, no more than 110,000 daltons, no more than 100,000 daltons, or no more than 95,000 daltons, as measured by GPC according to ASTM D6474. In certain embodiments, the cellulose ester can have a weight average absolute molecular weight ranging from 50,000 daltons to 150,000 daltons, 70,000 daltons to 120,000 daltons, or 80,000 daltons to 95,000 daltons, as measured by GPC according to ASTM D6474.

[0023] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester can have a crystallinity of at least 1%, at least 2%, at least 5%, at least 10%, at least 15%, or at least 20%, as measured according to ASTM F2625. Additionally or alternatively, in one embodiment, or in combination with other mentioned embodiments, the cellulose ester can have a crystallinity of 25% or less, 20% or less, 15% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less, as measured according to ASTM F2625. In certain embodiments, the cellulose ester can have a crystallinity of 1% to 99%, 1% to 50%, 1% to 30%, 1% to 20%, or 1% to 15%, as measured according to ASTM F2625.

[0024] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester can exhibit a glass transition temperature of at least 120°C, at least 125°C, at least 130°C, at least 135°C, at least 140°C, at least 145°C, at least 150°C, at least 155°C, at least 160°C, at least 165°C, at least 170°C, or at least 175°C, and / or 250°C, 245°C or less, 240°C or less, 235°C or less, 230°C or less, 225°C or less, 220°C or less, 215°C or less, 210°C or less, 205°C or less, 200°C or less, 195°C or less, 190°C or less, or 185°C or less.

[0025] Cellulose esters can be prepared by any method known in the art. Examples of methods for preparing cellulose esters are taught in Kirk-Othmer, Encyclopedia of Chemical Technology, 5th Edition, Vol.5, Wiley-Interscience, New York (2004), pages 394-444.

[0026] One method of producing cellulose ester involves esterification of cellulose by mixing cellulose with suitable organic acid, acid anhydride and catalyst.Then, cellulose is converted into cellulose triester.Then, cellulose triester can be added with a mixture of water and acid to carry out ester hydrolysis, and then filtered to remove gel particles or fibers.Then, water is added to the mixture to precipitate cellulose ester.Then, cellulose ester can be washed with water to remove reaction by-products, followed by dehydration and drying.

[0027] Cellulose, the starting material for producing cellulose esters, is available in a variety of grades and sources, including cotton linters, softwood pulp, hardwood pulp, corn fiber, other agricultural sources, and bacterial cellulose, among others. The starting material used to produce the cellulose ester can affect the hemicellulose content in the resulting cellulose ester.

[0028] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester can have a hemicellulose content of at least 0.25%, at least 0.5%, at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, or at least 7% by weight. Additionally or alternatively, in one embodiment, or in combination with other mentioned embodiments, the cellulose ester can have a hemicellulose content of 10% or less, 9% or less, 8% or less, 7% or less, greater than 6%, 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less by weight.

[0029] The dissolving solvent added to the dope mixer can include one or more solvents capable of dissolving cellulose esters, particularly cellulose diacetate and / or cellulose triacetate. In one embodiment, or in combination with other mentioned embodiments, the dissolving solvent includes a solvent selected from N,N-dimethylformamide, N,N-dimethylacetamide or dimethylsulfoxide, or a mixture thereof.

[0030] In one embodiment, or in combination with other mentioned embodiments, acetone as dissolving solvent is minimized or avoided.In certain embodiments (such as when N,N-dimethylacetamide is present in dope), dope comprises 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, or 0% by weight of acetone based on the total weight of cellulose ester dope.

[0031] The cellulose ester may be added to the dope so that the dope contains at least 5% by weight, at least 8% by weight, at least 10% by weight, at least 12% by weight, at least 15% by weight, at least 18% by weight, at least 20% by weight, or at least 22% by weight of cellulose ester, and / or 35% by weight or less, 33% by weight or less, 30% by weight or less, 29% by weight or less, 25% by weight or less, 22% by weight or less, or 20% by weight or less of cellulose ester, based on the total weight of the dope. In a specific embodiment, the cellulose ester dope contains 5% by weight to 35% by weight, 10% by weight to 33% by weight, 12% by weight to 30% by weight, 15% by weight to 29% by weight, or 25% by weight to 29% by weight of cellulose ester, based on the total weight of the dope.

[0032] In one embodiment, or in combination with other mentioned embodiments, cellulose ester is present in the dope at a level of at least 35% by weight, at least 40% by weight, at least 55% by weight, at least 65% by weight, at least 75% by weight, at least 85% by weight, at least 95% by weight, at least 98% by weight, or 100% by weight, based on the total solid content in the dope.In certain embodiments, cellulose ester is present in the dope at 35%-100%, 45%-100%, 55%-100%, 55%-98%, 65%-98%, or 75%-98%, based on the total solid content in the dope.

[0033] In one embodiment, or in combination with other mentioned embodiments, when the cellulose ester comprises CDA, the dope comprises at least 10% by weight, at least 13% by weight, at least 15% by weight, at least 18% by weight, at least 20% by weight, at least 22% by weight, or at least 24% by weight of CDA based on the total weight of the dope, and / or 35% by weight or less, 33% by weight or less, 30% by weight or less, or 29% by weight or less of CDA. In a specific embodiment, the cellulose ester dope comprises 10% by weight to 35% by weight, 15% by weight to 33% by weight, 18% by weight to 33% by weight, 20% by weight to 30% by weight, or 24% by weight to 29% by weight of CDA based on the total weight of the dope.

[0034] In one embodiment, or in combination with other mentioned embodiments, when cellulose ester comprises CTA, the dope comprises at least 10% by weight, at least 10% by weight, at least 12% by weight, at least 15% by weight, at least 17% by weight, at least 19% by weight, or at least 21% by weight of CTA based on the total weight of the dope, and / or 27% by weight or less, 25% by weight or less, 24% by weight or less, or 22% by weight or less of CTA. In a specific embodiment, the cellulose ester dope comprises 10% by weight to 27% by weight, 12% by weight to 24% by weight, or 15% by weight to 22% by weight of CTA based on the total weight of the dope.

[0035] The dissolving solvent should be added in an amount sufficient to effectively dissolve the cellulose ester, thereby forming a cellulose ester dope. In one embodiment, or in combination with other mentioned embodiments, the cellulose ester dope can include at least 65% by weight, at least 70% by weight, at least 75% by weight, at least 80% by weight, at least 85% by weight, at least 90% by weight, or at least 95% by weight, or 99% by weight, and / or 99% by weight or less, 95% by weight or less, 90% by weight or less, or 85% by weight or less of one or more dissolving solvents based on the total weight of the dope. In certain embodiments, the cellulose ester dope includes 65% to 99% by weight, 70% to 95% by weight, 75% to 95% by weight, 80% to 95% by weight, or 90% to 99% by weight of one or more dissolving solvents based on the total weight of the dope.

[0036] The water or moisture content of dope can be kept relatively low.In one embodiment, or in combination with other mentioned embodiments, cellulose ester dope has a moisture content of 4% by weight or less, 3.5% by weight or less, 3% by weight or less, 2.5% by weight or less, 2% by weight or less, 1.5% by weight or less, 1.4% by weight or less, 1.3% by weight or less, 1.2% by weight or less, 1.1% by weight or less, 1% by weight or less, 0.9% by weight or less, 0.8% by weight or less, 0.7% by weight or less, or 0.6% by weight or less, based on the total weight of cellulose ester dope.

[0037] Depending on the type of cellulose ester and dissolving solvent used, the cellulose dope can exhibit a desired operating viscosity. In one embodiment, or in combination with other mentioned embodiments, the cellulose ester dope can exhibit a viscosity, measured at the spinning temperature used to produce the fibers, of at least 10 poise, at least 20 poise, at least 30 poise, at least 40 poise, at least 50 poise, at least 60 poise, at least 70 poise, at least 80 poise, at least 90 poise, or at least 100 poise, and / or 3,000 poise or less, 2,000 poise or less, 1,500 poise or less, 1,000 poise or less, 950 poise or less, 900 poise or less, 850 poise or less, 800 poise or less, 750 poise or less, 700 poise or less, 650 poise or less, 600 poise or less, 550 poise or less, or 500 poise or less. This spinning temperature is nominally the temperature of the dope when it passes through the spinneret and enters therein.The viscosity defined herein is the "zero" shear viscosity obtained by extrapolating to very low shear rate when viscosity is plotted against shear rate, or by using a Brookfield viscometer at low spindle RPM.Therefore, the "measurement time" threshold value does not reflect in any way the use or implementation of actual cellulose ester dope.

[0038] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester dope has a viscosity of at least 10 poise, at least 20 poise, at least 30 poise, at least 40 poise, at least 50 poise, at least 60 poise, at least 70 poise, at least 80 poise, at least 90 poise, or at least 100 poise, measured at 25° C., 50° C., 60° C., 70° C., 80° C., 90° C., 100° C., or 110° C. can exhibit a viscosity of at least 100 poise, and / or 5,000 poise or less, 4,000 poise or less, 3,000 poise or less, 2,000 poise or less, 1,500 poise or less, 1,000 poise or less, 950 poise or less, 900 poise or less, 850 poise or less, 800 poise or less, 750 poise or less, 700 poise or less, 650 poise or less, 600 poise or less, 550 poise or less, or 500 poise or less. It should be noted that this "when measured" standard does not require that the cellulose ester dope be used only at this specified temperature, rather, this temperature standard simply provides a temperature threshold for measuring the viscosity of the cellulose ester dope. Therefore, the "when measured" threshold does not reflect in any way the use or implementation of the actual cellulose ester dope. Viscosity can be measured using a Brookfield viscometer at low spindle RPM.

[0039] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester dope may contain some additives or no additives in addition to the cellulose ester.Such additives may include, but are not limited to, plasticizers, antioxidants, heat stabilizers, oxidation promoters, inorganics, pigments, colorants, antistatic agents, optical brighteners, lubricants, fillers, or combinations thereof.

[0040] In one embodiment, or in combination with other mentioned embodiments, organic acids (monofunctional and / or multifunctional) may be included to prevent color development in the final fiber, especially when the dope is heated to high temperatures. Examples of such acids include those selected from citric acid, malic acid, maleic acid, succinic acid, lactic acid, acetic acid, tartaric acid, or propane-1,2,3-tricarboxylic acid, or mixtures thereof.

[0041] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester dope comprises at least 0.01% by weight, at least 0.05% by weight, at least 0.06% by weight, at least 0.07% by weight, at least 0.08% by weight, at least 0.09% by weight, at least 0.1% by weight, at least 0.2% by weight, or at least 0.3% by weight, and / or 2% by weight or less, 1.5% by weight or less, 1.4% by weight or less, 1.3% by weight or less, 1.2% by weight or less, 1.1% by weight or less, 1% by weight or less, 0.9% by weight or less, or 0.8% by weight or less of a polyfunctional acid based on the weight of the dope. In a specific embodiment, the cellulose ester dope comprises 0.01% to 2% by weight, 0.01% to 1.5% by weight, 0.05% to 1.5% by weight, 0.08% to 1.3% by weight, or 0.1% to 1% by weight of a polyfunctional acid based on the total weight of the dope.

[0042] In one embodiment, or in combination with other mentioned embodiments (e.g., when N,N-dimethylacetamide is present in the dope), the dope contains 0% by weight cellulose nanocrystals, including rod-like nanoparticles (e.g., less than 20 nm in diameter and less than 500 nm in length) produced by controlled acid hydrolysis of cellulose-based materials such as plants and trees.

[0043] In one embodiment, or in combination with other mentioned embodiments, the dope contains 20% by weight or less, 15% by weight or less, 10% by weight or less, 5% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, or 0% by weight or less of a polymer that is not a cellulose ester, based on the total solids content in the dope.

[0044] In one embodiment, or in combination with other mentioned embodiments, the total weight of any polyurethane, polyolefin, nylon, polyester, and / or polyurethane urea that may be present in the cellulose ester dope is 65% by weight or less, 60% by weight or less, 55% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, or 0% by weight, based on the total solids in the cellulose ester dope.

[0045] In one embodiment, or in combination with other mentioned embodiments, the polyurethane may be present in the cellulose ester dope at a level of 10% by weight or less, 9% by weight or less, 8% by weight or less, 7% by weight or less, 6% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, or 0% by weight, based on the total solids in the cellulose ester dope.

[0046] In one embodiment, or in combination with other mentioned embodiments, the polyurethane urea that may be present in the cellulose ester dope is present at a level of 10% by weight or less, 9% by weight or less, 8% by weight or less, 7% by weight or less, 6% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, or 0% by weight, based on the total solids in the cellulose ester dope.

[0047] In one embodiment, or in combination with other mentioned embodiments, the acrylonitrile-vinyl acetate copolymer that may be present in the cellulose ester dope is present at a level of 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, or 0% by weight, based on the total solids in the cellulose ester dope.

[0048] In one embodiment, or in combination with other mentioned embodiments, dope is prepared by mixing cellulose ester, solvent and any other components at low temperature.In some embodiments, this mixing is carried out by mixing at least 45°C, at least 46°C, at least 47°C, at least 48°C, at least 49°C, at least 50°C, at least 51°C, at least 52°C, at least 53°C, at least 54°C, at least 55°C, at least 56°C, at least 57°C, at least 58°C, at least 59°C, or at least 60°C, and / or at or below 140°C, at or below 130°C, at or below 120°C, at or below 110°C, at or below 105°C, at or below 104°C, at or below 103°C, at or below 102°C, at or below 101°C, at or below 100°C, at or below 99°C, at or below 98°C, at or below 97°C, at or below 96°C, or at or below 95°C. In certain embodiments, the temperature is between 45°C and 140°C, between 45°C and 105°C, between 47°C and 103°C, or between 50°C and 100°C.

[0049] In one embodiment, or in combination with other mentioned embodiments, the mixing is carried out for at least 5 minutes, at least 6 minutes, at least 8 minutes, at least 10 minutes, at least 12 minutes, at least 14 minutes, or at least 15 minutes, and / or for up to 48 hours, up to 36 hours, up to 24 hours, up to 20 hours, up to 16 hours, up to 12 hours, or up to 8 hours. In certain embodiments, the time is between 5 minutes and 48 hours, between 5 minutes and 36 hours, between 5 minutes and 24 hours, or between 5 minutes and 8 hours.

[0050] In one embodiment, or in combination with other mentioned embodiments, dope is prepared by first slurrying cellulose ester, solvent and any other components, and then cooling to very low temperature.In certain embodiments, this temperature is at least -100°C, at least -75°C, at least -70°C, at least -65°C, at least -60°C, at least -55°C, or at least -50°C, and / or 5°C or less, 4°C or less, 3°C or less, 2°C or less, 1°C or less, 0°C or less, -5°C or less, or -10°C or less, and is stored at any of the above temperatures for at least 1 hour, at least 2 hours, at least 3 hours, at least 4 hours, at least 5 hours, at least 6 hours, at least 7 hours, at least 8 hours, at least 9 hours, or at least 10 hours, and / or 48 hours or less, 36 hours or less, 30 hours or less, 24 hours or less, or 15 hours or less. In certain embodiments, the temperature is -100°C to 5°C, -75°C to 5°C, -75°C to 0°C, -65°C to 0°C, or 50°C to -5°C, and / or the storage time is 1 hour to 48 hours, 3 hours to 36 hours, 5 hours to 24 hours, or 7 hours to 10 hours. In certain embodiments, the dope is rewarmed and mixed at room temperature before spin drying.

[0051] After the cellulose ester dope is formed, it can be sent to an optional dope holding tank for temporary storage and / or degassing. The dope holding tank can include any conventional storage tank known in the art that can store the cellulose ester dope. While stored in the holding tank, the cellulose ester dope can be subjected to conditions that promote maintaining the physical properties of the dope and / or removing air bubbles introduced during the mixing process. The temperature and pressure of the holding tank and / or degassing tank can be optimized as needed to enhance and maintain the quality of the cellulose ester dope.

[0052] The cellulose ester dope can then be pumped from the dope holding tank to a filter to remove large, undesirable particles and gels from the cellulose ester dope prior to spinning. The filter can include any conventional filter device and filter type known in the art. After filtering, the filtered cellulose ester dope can be pumped to a spinneret located near or in an evaporation chamber or cabinet.

[0053] The cellulose ester dope can be metered through a spinneret to form one or more fibers. The shape and size of one or more holes in the spinneret helps determine the cross-section of the fiber. The number of holes in the spinneret face determines the number of fibers that are simultaneously formed as the dope is metered into the spinneret. As the dope passes through the holes in the spinneret face, individual fibers are formed.

[0054] More specifically, in one embodiment, or in combination with other mentioned embodiments, the cellulose ester dope can be spun at a speed of 10 to 1000 m / min through spinneret holes having designs known in the art (e.g., having a hole area equivalent to a circular diameter of 20 to 200 microns). In one embodiment, or in combination with other mentioned embodiments, the spinneret can be maintained at a temperature of at least 75°C, at least 80°C, at least 85°C, at least 90°C, at least 95°C, or at least 100°C, and / or at or below 175°C, at or below 170°C, at or below 165°C, at or below 160°C, at or below 155°C, or at or below 150°C. In certain embodiments, the spinneret head can be maintained at a temperature in the range of 75°C to 175°C, 85°C to 165°C, 95°C to 160°C, or 100°C to 150°C.

[0055] In the spinneret, the cellulose ester dope can be extruded through a number of holes to form continuous cellulose ester fibers. In the spinneret, the fibers can be drawn to form bundles of a number of individual fibers, or hundreds of individual fibers, or even 1,000 individual fibers. Each of these bundles can contain at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 150, at least 200, at least 250, at least 300, at least 350, or at least 400, and / or up to 1000, up to 900, up to 800, up to 700, or up to 600 fibers. The spinneret can be operated at any speed suitable for producing individual filament fibers, which are then assembled into bundles having a desired size and shape. As used herein, the term "individual filament fibers" refers to the continuous filaments that are initially produced by each hole in the face of the spinneret.

[0056] The fibers are extruded through a spinneret into a vertical spinning cabinet, the walls of which are nominally at 150° C. to 240° C. and which may contain gases nominally at 200° C. to 500° C., where the solvent is flashed off or evaporated. In certain embodiments, the evaporating comprises exposing the spun fiber to a temperature of at least 100°C, at least 110°C, at least 120°C, at least 130°C, at least 140°C, at least 145°C, at least 150°C or more, at least 153°C or more, at least 155°C, at least 160°C, at least 165°C, at least 170°C, at least 175°C, at least 180°C, at least 185°C, or at least 189°C, and / or 500°C or less, 400°C or less, 375°C or less, 350°C or less, 325°C or less, 300°C or less, 275°C or less, 250°C or less, 240°C or less, 230°C or less, or 220°C or less. In certain embodiments, the temperature is between 100°C and 500°C, between 110°C and 400°C, between 120°C and 375°C, between 130°C and 350°C, between 140°C and 300°C, or between 150°C and 250°C.

[0057] It should be noted that the cellulose ester fiber formed may be in the form of a single component fiber formed from only one material (e.g., cellulose ester) or a homogeneously blended composition, and therefore is not considered to be "bicomponent" or "multicomponent" characterized by internal phases or boundaries that depict different compositions within the outer surface of the fiber.In one embodiment, or in combination with other mentioned embodiments, the resulting cellulose ester fiber can comprise at least 50% by weight, at least 55% by weight, at least 60% by weight, at least 65% by weight, at least 70% by weight, at least 75% by weight, at least 80% by weight, at least 85% by weight, at least 90% by weight, at least 95% by weight, at least 99% by weight, or at least 99.9% by weight of cellulose ester based on the total weight of the fiber.In certain embodiments, the cellulose ester fiber can be formed entirely from cellulose ester.

[0058] The individual cellulose ester fibers exiting the spinneret can have any suitable cross-sectional shape. Exemplary cross-sectional shapes include, but are not limited to, circular or non-circular. In one embodiment, or in combination with other mentioned embodiments, the individual fibers exiting the spinneret can have a substantially circular cross-sectional shape. As used herein, the term "cross-section" generally refers to the cross-section of the fiber measured in a direction perpendicular to the longitudinal direction of the fiber. The cross-section of the fiber can be determined and measured using quantitative image analysis ("QIA").

[0059] The cross-sectional shape of an individual fiber can also be characterized according to the deviation from a circular cross-sectional shape. In some cases, this deviation can be characterized by the shape factor of the fiber. The shape factor is determined by the following formula: shape factor = circumference / (4π x cross-sectional area) 1 / 2. In some embodiments, the shape factor of an individual cellulose ester fiber can be 1 to 2, 1 to 1.8, 1 to 1.7, 1 to 1.5, 1 to 1.4, 1 to 1.25, 1 to 1.15, or 1 to 1.1. A fiber with a perfectly circular cross-sectional shape has a shape factor of 1. The shape factor can be calculated from the cross-sectional area of ​​the fiber, which can be measured using a QIA.

[0060] Additionally, in certain embodiments, the cellulose ester fibers can be in the form of solid fibers (fibers having a solid cross-sectional shape with no apertures therein) rather than in the form of hollow fibers.

[0061] In one embodiment, or in combination with other mentioned embodiments, a typical spinning cabinet for spandex fibers can have more than 30 ends (or yarns), but for cellulose esters, it is desirable to have no more than 30 ends per cabinet, no more than 25 ends per cabinet, no more than 20 ends per cabinet, no more than 15 ends per cabinet, no more than 10 ends per cabinet, no more than 8 ends per cabinet, no more than 6 ends per cabinet, no more than 4 ends per cabinet. Reducing the number of ends in a vertical spinning cabinet allows for sufficient solvent evaporation at lower temperatures, which is beneficial in preventing discoloration of the fibers.

[0062] In one embodiment, or in combination with other mentioned embodiments, it is desirable for the cellulose ester fibers to be drawn down at a ratio of 2x or less, 1.8x or less, 1.6x or less, 1.4x or less, or 1.2x or less, where the drawdown ratio is defined as the ratio of the fiber velocity at the exit of the vertical spinning cabinet to the fiber velocity at the exit of the spinneret holes.

[0063] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester fibers and / or yarns made therefrom are cellulose ester fibers having a tensile strength greater than or equal to 1000 MPa (1000 MPa) and / or a tensile strength greater than or equal to 1000 MPa (1000 MPa).

[0033] The fiber may exhibit a tenacity of at least 0.2 g / denier, at least 0.3 g / denier, at least 0.4 g / denier, at least 0.5 g / denier, at least 0.6 g / denier, at least 0.7 g / denier, at least 0.8 g / denier, at least 0.9 g / denier, at least 1 g / denier, at least 1.1 g / denier, at least 1.2 g / denier, at least 1.3 g / denier, at least 1.4 g / denier or more, at least 1.5 g / denier, at least 1.6 g / denier, at least 1.7 g / denier, at least 1.8 g / denier, 1.9 g / denier, or at least 2 g / denier, and / or 3.0 g / denier or less, or 2.5 g / denier or less, 2.3 g / denier or less, 2.1 g / denier or less, 2 g / denier or less, or 1.9 g / denier or less.

[0064] Elongation, also called elongation at break, is expressed as a percentage and is a measure of how much a yarn or filament can stretch before breaking.In one embodiment, or in combination with any other mentioned embodiment, the cellulose ester fiber and / or the yarn made therefrom can exhibit an elongation at break of at least 10%, at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, at least 20%, at least 21%, at least 22%, at least 23%, at least 24%, at least 25%, at least 26%, at least 27%, at least 28%, at least 29%, or at least 30%, as measured according to ASTM D22556.

[0065] The Silk Factor ("SF") is an empirically determined relationship between tenacity and elongation used to predict the failure envelope of a given fiber. The Silk Factor can be used to characterize the suitability of a yarn or fiber for use in a given process and is calculated based on the following formula: Silk factor = tenacity x √ elongation In one embodiment, or in combination with other mentioned embodiments, the cellulose ester fibers and / or yarns produced therefrom can exhibit a silk factor of at least 5.0, at least 6.0, at least 7.0, or at least 7.6, where elongation is expressed as a percentage and tenacity is expressed in grams / denier.

[0066] As mentioned above, cellulose ester fiber is formed as continuous filament fiber.Therefore, in one embodiment, or in combination with other mentioned embodiments, cellulose ester fiber can have aspect ratio (L / D) of at least 10:1, at least 20:1, at least 30:1, at least 40:1, at least 50:1, at least 100:1, at least 500:1, at least 1,000:1, or at least 10,000:1.

[0067] The continuous filament fiber can be accumulated on a core or tube at the winder after evaporation or solvent flash-off and sent to an optional downstream process. Of note, since this disclosure is directed to a dry spinning process, the fiber is not passed through or drawn into a coagulation bath after evaporation or solvent flash-off. The fiber can be wound around a take-up roll, which provides tension to draw the fiber into a downstream process step, which can include, for example, one or more annealing sections, winders, crimpers, cutters, or combinations thereof.

[0068] In one embodiment, or in combination with other mentioned embodiments, the spandex yarn bobbin is wound with a significant amount of winder draw, the winder speed is typically 5% faster than the speed of the previous roll, and in the case of cellulose ester continuous filament fibers, the winder draw ratio is desirably less than 3%, the winder draw ratio is less than 2%, the winder draw ratio is less than 1%, the winder draw ratio is less than 0.8%, and the winder draw ratio is less than 0.5%.

[0069] The continuous filament cellulose ester fibers may be collected into bundles, bands, or yarns, which may contain a plurality of cellulose ester fibers, each of which may contain at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 150, at least 200, at least 250, at least 300, at least 350, or at least 400, and / or up to 1,000, up to 900, up to 800, up to 700, or up to 600 individual fibers.

[0070] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester fibers and / or bundles, bands or yarns of cellulose ester can pass through a crimping zone where a patterned wavy shape is imparted to at least a portion or substantially all of the individual fibers. When used, the crimping zone includes at least one crimping device for mechanically crimping the fibers. In general, it is desirable that the cellulose ester fibers are not crimped by thermal or chemical means (e.g., hot water bath, steam, air jet or chemical coating), but are instead mechanically crimped using a suitable crimper. One example of a suitable type of mechanical crimper is a "stuffing box" or "stuffer box" crimper that utilizes multiple rollers to generate friction and buckle the fibers to form a crimp. Other types of crimpers can also be suitable. Examples of suitable equipment for applying crimped fibers are described, for example, in U.S. Pat. Nos. 9,179,709, 2,346,258, 3,353,239, 3,571,870, 3,813,740, 4,004,330, 4,095,318, 5,025,538, 7,152,288, and 7,585,442, each of which is incorporated by reference herein to the extent not inconsistent with the present disclosure.

[0071] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester fibers can be crimped to have a crimp frequency, measured according to ASTM D3937-12, of at least 5, at least 7, at least 10, at least 12, at least 13, at least 15, at least 17, and / or no more than 30, no more than 27, no more than 25, no more than 23, no more than 20, or no more than 19 crimps per inch ("CPI"). In certain embodiments, the average CPI of the fibers used to manufacture the cellulose ester bundles, bands or yarns and / or various downstream products can range from 7 to 30 CPI, 10 to 30 CPI, 10 to 27 CPI, 10 to 25 CPI, 10 to 23 CPI, 10 to 20 CPI, 12 to 30 CPI, 12 to 27 CPI, 12 to 25 CPI, 12 to 23 CPI, 12 to 30 CPI, 15 to 27 CPI, 15 to 23 CPI, 15 to 20 CPI, or 15 to 19 CPI.

[0072] In one embodiment, or in combination with other mentioned embodiments, the crimp amplitude of the fibers when crimped can vary, for example, be at least 0.85, 0.90, 0.93, 0.96, 0.98, 1.00, or 1.04 mm. Additionally or alternatively, in one embodiment, or in combination with other mentioned embodiments, the crimp amplitude of the fibers can be at most 1.75, at most 1.70, at most 1.65, at most 1.55, at most 1.35, at most 1.28, at most 1.24, at most 1.15, at most 1.10, at most 1.03, or at most 0.98 mm.

[0073] Furthermore, in one embodiment, or in combination with other mentioned embodiments, cellulose ester fibers, cellulose ester bundles, bands or yarns, and / or staple fibers produced therefrom can have a crimp ratio of at least 1:1. As used herein, "crimp ratio" refers to the ratio of uncrimped tow length / crimped tow length. In certain embodiments, cellulose ester fibers, cellulose ester yarns, and / or staple fibers produced therefrom can have a crimp ratio of at least 1:1, at least 1.1:1, at least 1.125:1, at least 1.15:1, or at least 1.2:1.

[0074] Crimp amplitude and crimp ratio are measured according to the procedures outlined in U.S. Patent Application No. 2020 / 0299822, which is incorporated by reference herein to the extent not inconsistent with the present disclosure.

[0075] Additionally or alternatively, in one embodiment or in combination with other mentioned embodiments, the cellulose ester fibers and / or bundles, bands or yarns formed therefrom may be applied with one or more types of surface finishes. Application methods are not limited and may include spraying, wick application, using immersion, or using squeeze, lick or kiss rollers. The location of application of the finish to the fibers may vary depending on the function of the finish. For example, a lubricating finish may be applied after spinning and before crimping, or before collecting the fibers into a bundle. Cutting lubricants and / or antistatic lubricants may be applied before or after crimping and before drying. A suitable amount of all finishes (whether lubricants, cutting lubricants, antistatic finishes, or otherwise) on the cellulose ester fibers can be at least 0.01, at least 0.02, at least 0.05, at least 0.10, at least 0.15, at least 0.20, at least 0.25, at least 0.30, at least 0.35, at least 0.40, at least 0.45, at least 0.50, at least 0.55, or at least 0.60 percent finish-on-yarn ("FOY") based on the weight of the dry cellulose ester fibers. Additionally or alternatively, in one embodiment, or in combination with other mentioned embodiments, the cumulative amount of finishes can be present in an amount of 2.5 or less, 2.0 or less, 1.5 or less, 1.2 or less, 1.0 or less, 0.9 or less, 0.8 or less, or 0.7 or less percent FOY based on the total weight of the dry fibers. The amount of finish on the fibers as expressed in weight percent can be determined by solvent extraction. As used herein, "FOY" or "finish on yarn" refers to the amount of finish on the fiber or yarn minus the added water.

[0076] In one embodiment, or in combination with other mentioned embodiments, cellulose ester fiber can include at least one plasticizer, or can be free of plasticizer. Cellulose ester fiber can include less than 30% by weight, less than 12% by weight, less than 10% by weight, less than 9% by weight, less than 8% by weight, less than 7% by weight, less than 6% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, less than 1% by weight, less than 0.5% by weight of at least one plasticizer, based on the total weight of cellulose ester fiber. When plasticizer is present, it can be incorporated into the fiber itself by spinning the dope containing the plasticizer contained in the flakes used to make the dope, and / or it can be applied to the surface of the fiber or filament by any of the methods used to apply the finish. If desired, plasticizer can be included in the finish formulation.

[0077] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester fibers and / or yarns formed therefrom can be biodegradable. As used herein, the term "biodegradable" generally refers to the tendency of a material to chemically decompose under certain environmental conditions. The degree of degradation can be characterized by the weight loss of a sample exposed to certain environmental conditions for a given period of time. In some examples, the cellulose ester fibers and / or yarns formed therefrom can exhibit a weight loss of at least 5%, at least 10%, at least 15%, or at least 20% after burial in soil for 60 days, and / or a weight loss of at least 15%, at least 20%, at least 25%, at least 30%, or at least 35% after exposure in a composting device for 15 days. However, the rate of degradation can vary depending on the specific end use of the fibers. Exemplary test conditions are provided in U.S. Pat. Nos. 5,870,988 and 6,571,802, which are incorporated herein by reference.

[0078] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester fibers and / or yarns formed therefrom can be compostable. To be considered "compostable," a material must meet four criteria: (1) the material must be biodegradable; (2) the material must be disintegrable; (3) the material must not contain more than a maximum amount of heavy metals; and (4) the material must not be ecotoxic. The term "disintegrability" refers to the tendency of a material to physically break down into small pieces when exposed to certain conditions. Disintegration depends on the material itself as well as the physical size and composition of the article being tested. Ecotoxicity measures the effect of a material on plant life, and the heavy metal content of the material is determined according to procedures set forth in standard test methods.

[0079] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester fibers and / or yarns formed therefrom can be industrially compostable, home compostable, or both. In such an embodiment, the cellulose ester fibers can meet four criteria: (1) they are biodegradable in that at least 90% of the carbon content is converted within 180 days; (2) they are disintegratable in that at least 90% of the material disintegrates within 12 weeks; (3) they do not contain heavy metals above the threshold established based on the EN12423 standard; and (4) the disintegrated content supports future plant growth as humus, where these four conditions are tested according to the methods of ASTM D6400, ISO 17088, or EN 13432, respectively.

[0080] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester fibers and / or yarns formed therefrom can exhibit at least 70 percent biodegradation in a period of 50 days or less when tested under aerobic composting conditions at ambient temperature (28° C.±2° C.) according to ISO 14855-1 (2012). In some cases, the cellulose ester fibers and / or yarns formed therefrom can exhibit at least 70 percent biodegradation in a period of 49 days or less, 48 ​​days or less, 47 days or less, 46 days or less, 45 days or less, 44 days or less, 43 days or less, 42 days or less, 41 days or less, 40 days or less, 39 days or less, 38 days or less, or 37 days or less when tested under these conditions, also referred to as "home composting conditions." These conditions may not be aqueous or anaerobic.

[0081] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester fibers and / or yarns formed therefrom can exhibit at least 60 percent biodegradation within 45 days when tested under aerobic composting conditions at a temperature of 58° C. (± 2° C.) according to ISO 14855-1 (2012). In some cases, when tested under these conditions, also referred to as "industrial composting conditions," they can exhibit at least 60 percent biodegradation within 44 days. These may not be aqueous or anaerobic conditions.

[0082] The resulting cellulose ester fibers may be used to produce a wide variety of end products, such as tow bands, staple fibers, filament yarns, spun yarns, woven articles, nonwoven articles, and / or knitted textiles.

[0083] In one embodiment, or in combination with other mentioned embodiments, the above-mentioned cellulose ester fibers and / or cellulose ester yarns can be cut into staple fibers. Any suitable type of cutting device can be used that can cut the fibers to the desired length without excessive damage to the fibers. Examples of cutting devices include, but are not limited to, rotary cutters, guillotines, stretch breaking devices, reciprocating blades, or combinations thereof. Once cut, the cellulose ester staple fibers can be baled or otherwise bagged or packaged for subsequent transportation, storage, and / or use. In one embodiment, or in combination with other mentioned embodiments, the d50 length of the staple fibers can be at least 5 mm, at least 10 mm, at least 20 mm, at least 30 mm, at least 40 mm, or at least 50 mm, and / or 150 mm or less, 140 mm or less, 130 mm or less, 125 mm or less, 120 mm or less, 115 mm or less, 110 mm or less, 105 mm or less, 100 mm or less, or 95 mm or less.

[0084] Additionally or alternatively, in one embodiment, or in combination with other mentioned embodiments, the denier per filament (weight in grams per 9000 m of fiber length) or "DPF" of the cellulose ester fiber (whether cellulose ester staple fiber or cellulose ester continuous fiber) can range from 0.5 to less than 20. The specific measurement method is not limited and may include the ASTM 1577-07 method using the FAVIMAT oscillating mirror procedure, microbalance weight measurement of a sample of known length, or width analysis using a convenient optical microscope or analytical device, if the staple fiber is obtained as a cut filament. The DPF may also be correlated to the maximum width of the fiber.

[0085] In one embodiment, or in combination with other mentioned embodiments, the staple fibers can be processed into cellulose ester spun yarns. Spun yarns are continuous strands that contain short staple fibers mechanically intertwined by the staple yarn spinning process. The staple yarn spinning process can be, but is not limited to, ring spinning, open-end spinning, air-jet spinning, compact spinning, silo spinning, vortex spinning, worsted spinning, semi-worsted spinning, wool spinning, and wet spinning using flax.

[0086] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester fibers can be processed into nonwoven articles, such as nonwoven textiles. Exemplary nonwoven articles can include wet-laid nonwoven articles, air-laid nonwoven articles, carded articles, and / or dry-laid nonwoven articles.

[0087] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester yarns can be processed into textile articles, such as woven textiles. Woven textiles can be formed on a loom by interlacing the warp and weft strands of at least two yarns, where the warp strands are oriented parallel and the weft strands are interlaced in an alternating pattern above and below the warp strands at an angle to the orientation of the warp strands.

[0088] In one embodiment, or in combination with other mentioned embodiments, the cellulose ester yarns can be processed into knitted articles, such as knitted textiles. Such knitted textiles can be formed by interlocking the loops of the yarns.

[0089] In one embodiment, or in combination with other mentioned embodiments, the end products described herein, including staple fibers, yarns, nonwoven articles, knitted articles, and woven articles, can comprise, consist essentially of, or consist of cellulose ester fibers. The end articles described herein, including staple fibers, yarns, nonwoven articles, knitted articles, and woven articles, can comprise at least 0.25, at least 0.5, at least 0.75, at least 1, at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 12, at least 15, at least 18, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, at least 70, at least 75, at least 80, at least 85, at least 90, at least 95, at least 99, or at least 99.9 weight percent of one or more cellulose ester fibers, based on the total weight of the article. Additionally or alternatively, in one embodiment, or in combination with other mentioned embodiments, final articles described herein, including staple fibers, yarns, nonwoven articles, knitted articles, and woven articles, comprise 99% or less, 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, or 5% or less by weight of one or more cellulose ester fibers, based on the total weight of the article. In certain embodiments, the final article may be formed entirely from cellulose ester fibers or may include one or more cellulose ester fibers in the range of 0.25-50%, 1-99%, 1-50%, 50-99%, 1-20%, or 0.25-5% by weight based on the total weight of the article.

[0090] Further advantages of various embodiments will be apparent to those skilled in the art upon reviewing the disclosure herein and the examples below. It will be understood that the various embodiments described herein are not necessarily mutually exclusive, unless otherwise indicated herein. For example, features described or illustrated in one embodiment may, but do not necessarily, be included in other embodiments. Thus, the present disclosure encompasses various combinations and / or integrations of the specific embodiments described herein.

[0091] definition It should be understood that the following is not intended to be an exhaustive list of defined terms, as other definitions may be provided in the preceding description, for example, with use of the defined term in context.

[0092] As used herein, the terms "a," "an," and "the" mean one or more.

[0093] As used herein, the term "and / or," when used in a list of two or more items, means that any one of the listed items can be used alone, or any combination of two or more of the listed items can be used. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone, B alone, C alone, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C.

[0094] As used herein, the terms "comprising," "comprises," "comprise," "contain," "containing," and "contains" are open-ended transitional terms used to transition from the subject matter listed before the term to one or more elements listed after the term. The one or more elements listed after the transitional term are not necessarily the only elements that make up the subject matter.

[0095] As used herein, the terms "having," "has," and "have" have the same open-ended meaning as "comprising," "comprises," and "comprise" above.

[0096] As used herein, the terms "including," "include," and "included" have the same open-ended meaning as "comprising," "comprises," and "comprise" above.

[0097] Number range In this description, numerical ranges are used to quantify certain parameters related to the present invention. It should be understood that when numerical ranges are provided, such ranges should be interpreted as providing literal support for the claim limitations that recite only the lower limit of the range and for the claim limitations that recite only the upper limit of the range. For example, a disclosed numerical range of 10 to 100 provides literal support for the claims that recite "greater than 10" (without upper limit) and the claims that recite "less than 100" (without lower limit).

[0098] Additionally, it should be understood that a list of numerical values ​​following a descriptor such as "at least" and "less than or equal to" provides literal support for a range based on all numerical values ​​following that descriptor. For example, a statement specifying "at least 2, 5, or 10, and / or less than or equal to 100, 50, or 25" provides literal support for the ranges "at least 25," "less than or equal to 50," and "at least 10 and 25." EXAMPLES

[0099] example The following examples illustrate methods according to the present disclosure, however, it should be understood that these examples are provided for illustrative purposes and should not be construed as limiting the overall scope.

[0100] Materials and Methods Dopes were prepared using a new bottle of reagent grade DMF to minimize contaminants or residual water. Each dope contained 25 grams of Eastman CA 394-60 Cellulose Acetate (CDA) and 75 grams of DMF solvent. For "hot mix", the DMF was first heated in the jar to the desired mixing temperature (typically 90°C) for 15 minutes before adding the CDA powder. The jar was capped to minimize air ingress. Mixing was initiated using a mechanical stirrer for 1 hour, after which samples were removed, cooled to room temperature, and tested for color and haze.

[0101] For the "cold mix" samples, CDA was slurried with DMF at room temperature, then the jar was sealed and inserted into a cooler filled with dry ice where it was kept for 4 hours, after which it was allowed to warm to room temperature, and then it was rotated overnight at room temperature to complete the homogenization of the mix. Some additional samples were tested by inserting the samples into a standard laboratory freezer rather than dry ice, but the procedure was otherwise the same.

[0102] The moisture content of the starting CDA was measured using a Sartorius Mark 3 analyzer (Goettingen, Germany). The moisture content of the as-received sample was 1.3 wt%. A wet CDA sample with a moisture level of 3.5 wt% was obtained from an open bag that had been in the laboratory for several months. A dry sample with a moisture level of 0.1 wt% was obtained by drying the wet sample in a vacuum oven at 60°C.

[0103] The color and haze of the dope samples were measured using a Hunter Labs Ultrascan Pro (Reston, VA) system by pouring the dope into a 20 mm cuvette. The cuvette was then inserted into a chamber for optical testing. Values ​​were typically measured after initial dope mixing and then again after 2 hours of storage at 120°C (to simulate the temperature of dry spinning). Color is reported in terms of L* (a gray scale indicator), a* (a red to green scale) and b* (blue to yellow). A high value of b* indicates the sample is more yellow. Some samples showed very low L*, meaning that they were very dark.

[0104] To more easily obtain color measurements, film castings of the samples were performed to simulate fiber spinning. The dopes were stored at 120°C, cooled to 90°C, and then cast onto a glass plate (also heated to 90°C) using a doctor blade. The nominal thickness of the final films ranged from 40μm to 70μm. The films were annealed at 180°C for 20 minutes to remove the solvent (some samples had a shorter annealing time to better simulate cabinet conditions). Color and haze were also measured on film samples using the same instrument in transmission mode (no correction was made for thickness differences).

[0105] Absolute molecular weights were measured on cast films using GPC by dispersing the samples in NMP solvent. The GPC column was calibrated using absolute Mw standards.

[0106] Examples 1-7 Effect of moisture and temperature on dope formation A comparison was made between wet and dry samples made using the "hot mix" and "cold mix" methods. Color and haze were measured on the dopes after mixing and after 2 hours at 120°C (see Table I). Sample #1 had the least yellowing (lowest b*) and was made using a wetter cellulosic sample with a cold mix process. Next best was #4, which was produced by hot mixing with a dry sample. It is interesting to note that "cold and wet" or "hot and dry" gave the lowest yellowness. All other combinations were worse and were nearly the same when compared to each other. [Table 1]

[0107] The haze values ​​of the films are also shown, and all had lower color compared to the dope. The slight difference in values ​​between the film samples is mainly due to the difference in film thickness.

[0108] Sample #5 was mixed at 50°C instead of 90°C to determine the practical lower temperature limit for hot mixing. This sample took approximately twice as long to dissolve as the 90°C sample. Another sample (#6) was mixed at room temperature and did not go into solution after 3 hours. However, the dope sample (#7) stored in the freezer at -10°C produced a high quality dope.

[0109] Examples 10-16 Additive effect by low temperature mixing In this example, the dopes were prepared using a similar low temperature mixing process as in Example 1 above, except that an additional amount of stabilizing additive (0.5% or 1% by weight) was also included. The starting moisture was 1.3 wt% for all CDA samples. The additives represent a range of possible stabilizers such as acids, buffers, and antioxidants. As observed and shown in Table II, the addition of citric acid had the most pronounced effect on b*, dramatically reducing color development. The citric acid and potassium citrate mixtures (#12 and #13) were next best, showing intermediate levels of color development. Samples #13, #14, and #15 still had undissolved solids remaining due to the additive not being completely dissolved. Acetate added as a buffer performed the worst, as it showed the highest amount of color development (worse than no additive added at all). Note that #15 had a low b*, but this sample darkened during heating, as indicated by the very low L*. [Table 2]

[0110] Examples 20-37 Additive effect by high temperature mixing at 90℃ These examples are similar to #10 above, except the samples were mixed at 90°C. Additionally, the additive levels for all additives were reduced to 0.15 wt% (except for #30-#32, which used 0.5 wt%) to minimize undissolved particles. All samples had a starting moisture of 1.3 wt% except for #31, which had 0.1% moisture. As with the low temperature mixes, various salts and buffers tended to worsen the color. Monofunctional acetic acid also had the same effect. The only sample with low color contained multifunctional citric acid. Succinic acid (#32), despite being as multifunctional as citric acid, did not produce good color in the film.

[0111] Note that the 0.15 wt% level is at the low end of the effective level for color reduction. A more ideal target based on the data would be around 0.3-0.7 wt%. At higher levels, such as 1% in the previous example, there is no significant improvement in color beyond the 0.5% addition.

[0112] Sample #31 also included a comparison to a highly dried sample with 0.5% citric acid to see if moisture made a difference. Comparing this to #10, #11 and #20 suggests that moisture is less important with citric acid, with amount being the more important variable.

[0113] Samples #32-37 were compared with other multifunctional acids, which may also aid in color stabilization. Citric acid was observed to provide better color control than succinic, malic, or tartaric acids. [Table 3]

[0114] Examples 40-48 Effect of Acid on Film Cast Color In this example, film samples were cast and annealed for various times. In samples #40 and #41, the films were cast from the same dope (#10). In #40, the film was cast and annealed in a hot air oven at 180°C for 20 minutes to dry the film (see Table IV). Note that the citric acid film is very yellow after 20 minutes. This is because it is above its melting point and degradation may have occurred due to exposure to oxygen. In a typical dry spinning cabinet, the temperature exposure is only for a few seconds (presumably with a nitrogen blanket). So, to better reflect the spinning conditions, a second film (#41) was cast and dried at 180°C for 4 minutes. This was the minimum time required for the film to dry. As observed, the color was significantly reduced and much better than the other samples. The sample was also completely dry and had no DMF odor. Finally, sample #47 was cast from the same dope but annealed at 150°C for 20 minutes. This sample also showed excellent color similar to that at 180°C for 4 minutes. In the remaining examples, samples of other acids were also cast into films and annealed using the 180°C for 4 minutes protocol. The dopes containing citric acid were less yellow than the control at all levels of citric acid addition. In contrast, the 0.5% malic and tartaric acids were slightly more yellow than the control. [Table 4]

[0115] The claims are not limited to the disclosed embodiments. The above-mentioned preferred embodiments of the present invention should be used only as examples, and should not be used in a limiting sense to interpret the scope of the present invention. Modifications to the above-mentioned exemplary embodiments can be easily made by those skilled in the art without departing from the spirit of the present invention.

[0116] The inventors hereby express their intention to rely on the doctrine of equivalents to determine and assess the reasonably fair scope of the invention for any device that does not materially depart from the literal scope of the invention as set forth in the claims, but falls outside that scope.

Claims

1. 1. A method for producing a cellulose ester fiber, comprising dry-spinning a cellulose ester dope through a spinneret to produce one or more of said fibers, wherein the cellulose ester dope comprises dissolved and / or dispersed solids (hereinafter "solids") and a solvent, wherein at least 35 wt % of the solids comprises a cellulose ester, and the solvent comprises N,N-dimethylformamide, N,N-dimethylacetamide, or dimethylsulfoxide, or a mixture thereof, with the proviso that when the solvent comprises N,N-dimethylformamide: (i) the cellulose ester dope contains 50% by weight or less of acetone based on the total weight of the cellulose ester dope, or (ii) the cellulose ester dope contains 0% by weight of cellulose nanocrystals based on the total weight of the cellulose ester dope; or (iii) both (i) and (ii); A method for producing a cellulose ester fiber, wherein the total mass of polyurethane, polyolefin, nylon, polyester and / or polyurethane urea when present in the cellulose ester dope is 60 mass% or less based on the total solid content in the cellulose ester dope.

2. The method of claim 1 , wherein the cellulose ester dope comprises up to 10% by weight of polyurethane or polyurethane urea based on the total solids in the cellulose ester dope.

3. 3. The method according to claim 1, wherein the cellulose ester dope comprises 50% by weight or less of the acrylonitrile-vinyl acetate copolymer based on the total solids content in the cellulose ester dope.

4. The method according to any one of claims 1 to 2, wherein the cellulose ester fibers contain at least 50% by mass of cellulose ester obtained from the cellulose ester dope.

5. The cellulose ester has a DS of at least 1.5 and / or 2.95 or less. アセチル The method according to any one of claims 1 to 2, comprising:

6. The method according to any one of claims 1 to 2, wherein the cellulose ester has a glass transition temperature of at least 120°C and / or not more than 250°C.

7. The dry spinning is spinning the cellulose ester dope to produce a spun fiber containing the solvent; and evaporating the solvent from the spun fibers; The method according to any one of claims 1 to 2, comprising:

8. The method of any one of claims 1 to 2, wherein the cellulose ester dope comprises a polyfunctional acid.

9. The method according to any one of claims 1 to 2, wherein the cellulose ester dope has a water content of 4% by weight or less based on the total weight of the cellulose ester dope.

10. The method of any one of claims 1 to 2, further comprising preparing the cellulose ester dope by slurrying the cellulose ester and the solvent, then cooling the dope to a temperature of at least -100°C and / or 5°C or less, and storing the dope at any of the above temperatures for at least 1 hour.

11. 3. The method according to claim 1, wherein the cellulose ester dope has a b* value of 0.75 or less.

12. A method for producing cellulose ester fibers formed according to any one of claims 1 to 2.

13. A method for producing a yarn comprising the cellulose ester fibers formed according to claim 12.

14. A method of making an article comprising the cellulose ester fibers formed according to claim 12.

15. A method of making a woven article comprising the cellulose ester fibers formed according to claim 12.

16. A method of making a nonwoven article comprising the cellulose ester fibers formed according to claim 12.

17. A method for producing staple fibers comprising the cellulose ester fibers formed according to claim 12.

18. 13. A method of making a knitted textile comprising the cellulose ester fibers formed according to claim 12.

19. The method of claim 7, wherein the step of evaporating the solvent from the spun fibers occurs in a spinning cabinet.

20. 20. The method of claim 19, wherein the spun fibers in the spinning cabinet are drawn down at a draw down ratio of 2:1 or less.