Patent Application
20240133120
Embodiments described generally relate to processes for imparting oil and grease resistance to paper products and to paper products having oil and grease resistance.
Paper material used to manufacture packages, e.g., cups, cartons, bowls, plates, etc., that are intended to come into contact with liquids and food is provided with a barrier coating at least on the inside, i.e., the side that will be in contact with the liquid or food. The barrier coating can make the package resistant against oils and grease, thereby enabling the package to contain the liquid or food without breaking down due to absorption of the oil and/or grease. The barrier coating, however, must be applied in relatively high concentrations for the package to meet performance targets. The high concentration needed for the barrier coating increases the costs associated with making the package and can limit machine runnability, package recyclability, and package compostability, all of which are undesirable.
There is a need, therefore, for improved processes for imparting oil and grease resistance to a paper product.
Processes for imparting oil and grease resistance to paper products and paper products having oil and grease resistance are provided. In some embodiments, the process for imparting oil and grease resistance to a paper product can include combining a plurality of fibers and water to produce a slurry; forming the slurry into a wet paper web; pressing and draining the wet paper web to produce a wet paper sheet; and drying the wet paper sheet to produce a dried paper sheet. A sizing composition can be applied to the slurry, applied to the wet paper web, applied to the wet paper sheet, applied to the dried paper sheet, or a combination thereof. A barrier compound can be applied to the dried paper sheet. The sizing composition can include one or more alkenyl succinic anhydride compounds. The barrier compound can include a polyolefin dispersion, a styrene acrylate emulsion, a sucrose ester, a modified starch, styrene maleic anhydride, an ethylene acrylic acid dispersion, a styrene acrylic acid, a polyvinyl alcohol, an ethylene vinyl alcohol, or a mixture thereof. The dried paper sheet can have an average KIT Value of at least 3.
In other embodiments, the process for imparting oil and grease resistance to a paper product can include combining a plurality of fibers and water to produce a slurry; forming the slurry into a wet paper web; pressing and draining the wet paper web to produce a wet paper sheet; and drying the wet paper sheet to produce a dried paper sheet. A sizing composition can be applied to the slurry, applied to the wet paper web, applied to the wet paper sheet, applied to the dried paper sheet, or a combination thereof. A barrier compound can be applied to the slurry, applied to the wet paper web, applied to the wet paper sheet, applied to the dried paper sheet, or a combination thereof. The sizing composition can include one or more alkenyl succinic anhydride compounds. The barrier compound can include a fluorochemical compound, a wax emulsion, or a mixture thereof. The dried paper sheet can have an average KIT Value of at least 3.
Paper products are also provided. In some embodiments, the paper product can include a paper substrate; a sizing composition disposed on the paper substrate; and a barrier compound disposed on the paper substrate. The sizing composition can include one or more alkenyl succinic anhydride compounds. The barrier compound can include a polyolefin dispersion, a styrene acrylate emulsion, a sucrose ester, a modified starch, styrene maleic anhydride, an ethylene acrylic acid dispersion, a styrene acrylic acid, a polyvinyl alcohol, an ethylene vinyl alcohol, a fluorochemical compound, a wax emulsion, or a mixture thereof. The paper product can have an average KIT Value of at least 3.
Oil and grease resistance can be imparted to a paper product by applying a sizing composition and a barrier compound to the paper product once made and/or during one or more steps of the manufacturing process used to make the paper product. The process for making the paper product can include combining a plurality of fibers and water to produce a slurry; forming the slurry into a wet paper web; pressing and draining the wet paper web to produce a wet paper sheet; and drying the wet paper sheet to produce a dried paper sheet. In some embodiments, the process for making the paper product can include taking an aqueous slurry that includes about 0.1 wt %, about 0.5 wt %, about 1 wt %, or about 1.5 wt % to about 2.5 wt %, about 3 wt %, about 4 wt %, or about 5 wt % of the plurality of fibers, based on the weight of the aqueous slurry, and dewatering the slurry to form a wet paper web that can include about 8 wt %, about 10 wt %, about 12 wt %, or about 15 wt % to about 17 wt %, about 21 wt %, about 23 wt %, or about 25 wt % of the plurality of fibers, based on the weight of the wet paper web. For example, the papermaking fibers can be deposited onto a foraminate surface to form the wet paper web. The wet paper web can be pressed and drained to produce a wet paper sheet that includes about 40 wt %, about 45 wt %, about 50 wt %, or about 55 wt % to about 60 wt %, about 65 wt %, about 70 wt %, about 75 wt %, about 80 wt %, or about 90 wt % of the plurality of fibers, based on the weight of the wet paper sheet. The wet paper sheet can then be dried to produce a dried paper sheet that can have a moisture content of about 0.1 wt %, about 0.5 wt %, about 1 wt %, about 2 wt %, about 3 wt % or about 4 wt % to about 6 wt %, about 8 wt %, about 10 wt %, or about 12 wt %, based on the weight of the dried paper sheet. In some embodiments, the dried paper sheet can be free of any moisture. Accordingly, transforming the slurry into the dried paper sheet can be accomplished via a series of steps that can include, but are not limited to, inertial dewatering (early forming section of the machine), press dewatering (press section of the machine), and/or thermally evaporating the water (dryer section of the machine). In some paper making machines, through-air drying cylinders can be located after the forming section and before the dryer section.
In some embodiments, the process for imparting oil and grease resistance to the paper product can include applying the sizing composition to the slurry, the wet paper web, the wet paper sheet, the dried paper sheet, or a combination thereof, and applying the barrier compound to the dried paper sheet. The dried paper sheet that includes the sizing composition and the barrier compound applied thereto can also be referred to as a paper product. In some embodiments, when the sizing composition and the barrier compound are applied during the same step of the paper making process, i.e., to the dried paper sheet, the sizing composition can be applied before the barrier compound. In other embodiments, when the sizing composition and the barrier compound are applied during the same step of the paper making process, i.e., to the dried paper sheet, the barrier compound can be applied before the sizing composition. In still other embodiments, when the sizing composition and the barrier compound are applied during the same step of the paper making process, i.e., to the dried paper sheet, the sizing composition and the barrier compound can be applied at the same time, e.g., as a mixture or can be separately applied to the dried paper sheet at the same time. In such embodiments, the sizing composition can be or can include, but is not limited to, one or more alkenyl succinic anhydride compounds and the barrier compound can be or can include, but is not limited to, a polyolefin dispersion, a styrene acrylate emulsion, a sucrose ester, a modified starch, styrene maleic anhydride, an ethylene acrylic acid dispersion, a styrene acrylic acid, a polyvinyl alcohol, an ethylene vinyl alcohol, or a mixture thereof.
In other embodiments, the process for imparting oil and grease resistance to the paper product can include applying the sizing composition and the barrier compound to the slurry, the wet paper web, the wet paper sheet, the dried paper sheet, or a combination thereof. The sizing composition and the barrier compound can be applied during the same step or during different steps of the paper making process. The sizing composition and the barrier compound, when applied during the same step of the paper making process can be applied separately or as a mixture. In some embodiments, when the sizing composition and the barrier compound are applied during the same step of the paper making process, the sizing composition can be applied before the barrier compound. In other embodiments, when the sizing composition and the barrier compound are applied during the same step of the paper making process, the barrier compound can be applied before the sizing composition. In such embodiments, the sizing composition can be or can include, but is not limited to, one or more alkenyl succinic anhydride compounds and the barrier compound can be or can include, but is not limited to, one or more fluorochemical compounds, one or more wax emulsions, or a mixture thereof.
The sizing composition and the barrier compound can be applied or otherwise contacted with the slurry, the wet paper web, the wet paper sheet, and/or the dried paper sheet via any suitable process or combination of processes. In some embodiments, the sizing composition and the barrier compound can independently be applied, depending at least in part on the particular step each ingredient is applied during the paper making process, via spraying, froth foaming, roll coating, gravure printing, dipping, and/or impregnation. When the sizing composition and/or the barrier compound is applied to the dried paper sheet, the sizing composition and/or the barrier compound can be applied to one side or to both sides of the dried paper sheet.
The combination of the sizing composition that includes the one or more alkenyl succinic anhydride compounds and one or more of the barrier compounds can provide the dried paper sheet, which can also be referred to as the paper product, with a sufficient oil and grease resistance, i.e., a desired average KIT value, while utilizing a relatively minimal amount of the barrier compound for a particular paper product. In some embodiments, the dried paper sheet or paper product can have an average KIT value of at least 3, at least 3.5, at least 4, at least 4.5, at least 5, at least 5.5, at least 6, at least 6.5, at least 7, at least 7.5, at least 8, at least 8.5, at least 9, at least 9.5, at least 10, at least 10.5, at least 11, at least 11.5, or at least 12. The average KIT value is the average of five (5) specimens, as measured according to the Grease Resistance Test for Paper and Paperboard T 559 pm-96 test method.
The amount of the sizing composition that can be used to size the dried paper sheet can vary depending, for example, on the particular sizing composition employed, the particular pulp involved, the specific operating conditions, the contemplated end-use of the dried paper sheet, and the like. Typical concentrations of the sizing composition, based on the dry weight of the plurality of fibers in the dried paper sheet or paper product, can be from about 0.1 kg (about 0.25 lbs) to about 9 kg (about 20 lbs) of the sizing composition per 907 kg (about 2,000 lbs) of the dried paper sheet. In some embodiments, the amount of the sizing composition, based on the dry weight of the plurality of fibers in the dried paper sheet or paper product, can be from about 0.2 kg (about 0.5 lbs), about 0.4 kg (about 0.5 lbs), or about 0.7 kg (about 1.5 lbs) to about 0.9 kg (about 2 lbs), about 2.3 kg (about 5 lbs), or about 4.5 kg (about 10 lbs) of the sizing composition per 907 kg (about 2,000 lbs) of the dried paper sheet.
In some embodiments, when the barrier compound includes the wax emulsion, the polyolefin dispersion, the styrene acrylate emulsion, the sucrose ester, the modified starch, styrene maleic anhydride, the ethylene acrylic acid dispersion, the styrene acrylic acid, the polyvinyl alcohol, the ethylene vinyl alcohol, or a mixture thereof, the dried paper sheet or paper product can include up to 4 grams (g) of the barrier compound per square meter of the dried paper sheet or paper product. In some embodiments, when the barrier compound includes the wax emulsion, the polyolefin dispersion, the styrene acrylate emulsion, the sucrose ester, the modified starch, styrene maleic anhydride, the ethylene acrylic acid dispersion, the styrene acrylic acid, the polyvinyl alcohol, the ethylene vinyl alcohol, or a mixture thereof, the dried paper sheet or paper product can include the barrier compound in an amount of from 1 g, 1.3 g, 1.5 g, 1.7 g, 2 g, 2.3 g, or 2.5 g to 2.7 g, 3 g, 3.3 g, 3.5 g, 3.7 g, or 4 g per square meter of the dried paper sheet or paper product. In some embodiments, when the barrier compound includes the wax emulsion, the polyolefin dispersion, the styrene acrylate emulsion, the sucrose ester, the modified starch, styrene maleic anhydride, the ethylene acrylic acid dispersion, the styrene acrylic acid, the polyvinyl alcohol, the ethylene vinyl alcohol, or a mixture thereof, the dried paper sheet or paper product can include the barrier compound in an amount of from 1 g, 1.3 g, 1.5 g, 1.7 g, 2 g, 2.3 g, or 2.5 g to 2.7 g, 3 g, 3.3 g, 3.5 g, 3.7 g, or 4 g per square meter of the dried paper sheet or paper product and can have an average KIT value of at least 3, at least 3.5, at least 4, at least 4.5, at least 5, at least 5.5, at least 6, at least 6.5, at least 7, at least 7.5, at least 8, at least 8.5, at least 9, at least 9.5, at least 10, at least 10.5, at least 11, at least 11.5, or at least 12.
In some embodiments, when the barrier compound includes the fluorochemical compound, the amount of the fluorochemical compound, based on the dry weight of the plurality of fibers in the dried paper sheet or paper product, can be from about 0.4 kg (about 0.9 lbs), about 0.5 kg (about 1.1 lbs), about 0.6 kg (about 1.3 lbs), about 0.7 kg (about 1.5 lbs), about 0.8 kg (about 1.8 lbs), about 0.9 kg (about 2 lbs), about 1 kP (about 2.2 lb), or about 1.1 kg (about 2.4 lbs) to 1.2 kg (about 2.6 lbs), about 1.3 kg (about 2.9 lbs), about 1.4 kg (about 3.1 lbs), about 1.5 kg (about 3.3 lbs), about 1.6 kg (about 3.5 lbs), about 1.7 kg (about 3.7 lbs), about 1.8 kg (about 4 lbs), about 1.9 kg (about 4.2 lbs), about 2 kg (about 4.4 lbs), about 2.1 kg (about 4.6 lbs), about 2.2 kg (about 4.8 lbs), or about 2.3 kg (about 5.1 lbs) of the fluorochemical compound per 907 kg (about 2,000 lbs) of the dried paper sheet. In some embodiments, when the barrier compound includes the fluorochemical compound, the amount of the fluorochemical compound, based on the dry weight of the plurality of fiber sin the dried paper sheet or paper product, can be from about 0.4 kg (about 0.9 lbs), about 0.5 kg (about 1.1 lbs), about 0.6 kg (about 1.3 lbs), about 0.7 kg (about 1.5 lbs), about 0.8 kg (about 1.8 lbs), about 0.9 kg (about 2 lbs), about 1 kP (about 2.2 lb), or about 1.1 kg (about 2.4 lbs) to 1.2 kg (about 2.6 lbs), about 1.3 kg (about 2.9 lbs), about 1.4 kg (about 3.1 lbs), about 1.5 kg (about 3.3 lbs), about 1.6 kg (about 3.5 lbs), about 1.7 kg (about 3.7 lbs), about 1.8 kg (about 4 lbs), about 1.9 kg (about 4.2 lbs), about 2 kg (about 4.4 lbs), about 2.1 kg (about 4.6 lbs), about 2.2 kg (about 4.8 lbs), or about 2.3 kg (about 5.1 lbs) of the fluorochemical compound per 907 kg (about 2,000 lbs) of the dried paper sheet and can have an average KIT value of at least 3, at least 3.5, at least 4, at least 4.5, at least 5, at least 5.5, at least 6, at least 6.5, at least 7, at least 7.5, at least 8, at least 8.5, at least 9, at least 9.5, at least 10, at least 10.5, at least 11, at least 11.5, or at least 12.
The plurality of fibers used to make the dried paper sheet can include any type of cellulosic fibers, any type of non-cellulosic fibers, and combinations of cellulosic and non-cellulosic fibers. The cellulosic fibers that can be used can be or can include, but are not limited to, sulfate (Kraft) fibers, sulfite fibers, soda fibers, neutral sulfite semi-chemical (NSSC) fibers, thermomechanical (TMP) fibers, chemi-thermomechanical (CTMP) fibers, groundwood (GWD) fibers, and any combination of these fibers. Any of the foregoing cellulosic fibers may be bleached or unbleached. These designations refer to wood pulp fibers that have been prepared by any of a variety of processes that are typically used in the pulp and paper industry. The non-cellulosic fibers can be or can include, but are not limited to, viscose rayon or regenerated cellulose fibers.
In some embodiments, further improvements in the oil and grease resistance of the paper product prepared with the sizing composition and the barrier compound can be obtained, for example, by curing the resulting dried paper sheet. This curing process can include heating the dried paper sheet to a temperature and for a time suitable to obtain the desired improved oil and grease resistance, typically by heating the dried paper sheet to temperatures of about 80° C. to about 150° C. for about 1 to about 60 minutes.
The paper products that can be made or otherwise formed, at least in part, from the dried paper sheet that has been treated with the sizing composition that includes the alkenyl succinic anhydride compound and the barrier compound can be or can include, but are not limited to, food take out boxes, baking paper, take out cups, ice cream containers, French fry and popcorn packaging, biscuits and sweets packaging, bread and pastry packaging, plates, bowls, food wrappers and liners, pet food containers, e.g., pet food bags, liquid packaging board, gypsum wall board liner, boxboard, sack paper, molded paper products, newspaper, printing paper, a grease proof label, oil proof paper, a fast-food board, fast-food wrapping paper, or any other paper product that oil and grease resistance is a desired property. In some embodiments, the paper product can be a molded paper product.
Liquid packaging board (LPB) typically is a paper-based board that is laminated on both sides with polyethylene. It is used to construct cartons that contain liquid beverages such as milk and juice. The polyethylene coating can prevent the penetration of liquid into the carton, which can result in its weakening and destruction. The liquid packaging board, however, is still susceptible to liquid penetration due to imperfections, e.g., cracks, in the polyethylene coating and, particularly, at the cut edges of the folded carton. Sizing chemicals can be added to the paperboard to reduce or prevent the penetration of liquids into this cut edge. The most common liquids packaged in liquid packaging board are dairy products like milk and cream. These products contain lactic acid and it can be difficult to prevent edge penetration by dairy products. The combination of the sizing composition that includes the alkenyl succinic anhydride and one or more of the barrier compounds disclosed herein can provide sufficient resistance to edge and crack penetration by the liquid stored therein.
The synthesis of alkenyl succinic anhydrides by the ene reaction of maleic anhydride and internal olefins is well known. The alkenyl succinic anhydrides can be prepared by heating a mixture that includes maleic anhydride and one or more olefins, e.g., one or more C12-C30 olefins. A molar ratio of the olefin(s) to the maleic anhydride can be about 1:1 to about 2:1. The olefin(s) and the maleic anhydride can be stirred and heated in an inert atmosphere at a temperature of from 180° C. to 230° C. The olefin(s) and the maleic anhydride can be heated for a time period of from 30 minutes, 1 hour, 1.5 hours, or 2 hours to 3 hours, 4 hours, 5 hours, or more to produce the alkenyl succinic anhydride compound. In some embodiments, a small amount, e.g., less than 1 wt %, of a suitable antioxidant can be added to the mixture to reduce unwanted side reactions and/or to reduce the overall color of the final product. After the reaction has been completed, at least a portion of any residual maleic anhydride and/or residual olefin(s) can be removed via vacuum distillation. Processes that can be used to produce alkenyl succinic anhydride compound can include those described in U.S. Pat. Nos. 3,821,069; 6,348,132; and 7,455,751.
In some embodiments, the one or more olefins that can be reacted with maleic anhydride to produce the alkenyl succinic anhydride compound can be an internal olefin that can have a chemical formula (I) of Rx—CH2—CH═CH—CH2—Ry, where Rx and Ry can independently be an alkyl group that includes 1 carbon atom to 20 carbon atoms. In some embodiments, Rx and Ry can independently be an alkyl group that includes from 1 carbon atom, 2 carbon atoms, 3 carbon atoms, 4 carbon atoms, 5 carbon atoms, or 6 carbon atoms to 20 carbon atoms.
In some embodiments, the alkenyl succinic anhydride compound can be prepared by reacting maleic anhydride and one or more substantially symmetrical C18-C28 internal olefins. Substantially symmetrical internal olefins are olefins in which the carbon-carbon double bond is situated within one carbon atom of the center of the hydrocarbon chain. In some embodiments, the substantially symmetrical internal olefin can be or can include, but is not limited to, 10-eicosene, 11-docosene, 12-tetracosene, 13-hexacosene, 14-octacosene, 9-eicosene, 10-heneicosene, 10-docosene, 11-tetracosene, 11-tricosene, 12-hexacosene, 12-pentacosene, 13-octacosene, 13-heptacosene, or a mixture thereof.
In some embodiments, the substantially symmetrical C18-C28 internal olefin(s) can be produced using the well-known metathesis process. In this case, an alpha olefin can be stirred and reacted in the presence of a metathesis catalyst. The metathesis catalyst can be oxides or organometallic materials based on various transition metals such as titanium, tungsten, rhenium, or ruthenium (Grubbs catalysts). The olefin can be heated or reacted at mild temperatures, depending, at least in part, on the catalyst and amount. The metathesis reaction is reversible and is dictated by equilibrium conditions. In the case of alpha olefins, ethylene gas is generated and removed to push the reaction equilibrium forward. For example, the reaction of a C12 alpha olefin with the appropriate metathesis catalyst would yield 11-docosene along with ethylene gas. The catalyst system can be homogeneous or non-homogeneous, continuous (fixed bed) or batch. See ‘Olefin Metathesis and Metathesis Polymerization’ by J. K. Mol (Published 1997).
In some embodiments, the alkenyl succinic anhydride can have a chemical formula of (II):
In other embodiments, the one or more alkenyl succinic anhydride compounds can be or can include, but are not limited to, dodecenylsuccinic anhydride, tridecenylsuccinic anhydride, tetradecenylsuccinic anhydride, pentadecenylsuccinic anhydride, hexadecenylsuccinic anhydride, heptadecenylsuccinic anhydride, octadecenylsuccinic anhydride, nonadecenylsuccinic anhydride, eicosenylsuccinic anhydride, henicosenylsuccinic anhydride, docosenylsuccinc anhydride, tricosenylsuccinic anhydride, tetracosenylsuccinic anhydride, pentacosenylsuccinic anhydride, hexacosenylsuccinic anhydride, or a mixture thereof.
The barrier compounds, i.e., the polyolefin dispersion, styrene acrylate emulsion, sucrose ester, modified starch, styrene maleic anhydride, ethylene acrylic acid dispersion, styrene acrylic acid, polyvinyl alcohol, ethylene vinyl alcohol, fluorochemical compound, and/or wax emulsion, that can be used to impart oil and grease resistance to a paper product are all well known in the art.
The polyolefin dispersion can be or can include any polyolefin dispersed in a liquid medium, e.g., water. In some embodiments, the polyolefin can be or can include, but is not limited to, one or more polyethylenes, one or more polypropylenes, one or more copolymers of ethylene and propylene, one or more copolymers of ethylene and octene, or any blend thereof. In some embodiments, the polyolefin dispersion can have a solids content of about 40 wt % to about 55 wt %. In some embodiments, the polyolefin dispersion can be or can include RHOBARR® 320 Barrier Dispersion available from The Dow Chemical Company.
In some embodiments, the styrene acrylate emulsion can have a solids content of about 40 wt % to about 55 wt %. In some embodiments, the styrene acrylate emulsion can be or can include TYKOTE® 6152 available from Mallard Creek Polymers.
In some embodiments, the styrene acrylic acid can be produced via reacting styrene and one or more acrylates, which includes acrylic acid and its esters, e.g., methyl acrylate, butyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate to produce the styrene acrylic acid. The styrene acrylic acid can be produced via the well-known emulsion polymerization technique.
The sucrose ester can be or can include saccharide fatty acid esters that can be or can include sucrose esters of fatty acids. In some embodiments, the saccharide fatty acid esters can include a saccharide moiety, including but not limited to a sucrose moiety, which can be substituted by an ester moiety at one or more of its hydroxyl hydrogens. In some embodiments, the sucrose ester can be in the form of a polyol fatty acid ester and a saccharide fatty acid ester blend.
The modified starch and the hydrophobic starch can be derived from any suitable starch. Starch includes natural products derived from plant matter, e.g., wheat, maize, potato, rice, tapioca or sorghum starches, and other starches, that can include polymers or polysaccharides of high molecular weight. The plant matter can be treated by grinding-steeping and centrifugation to extract the starch. Native or natural starch is the product extracted without molecular modification. In some embodiments, the modified starch can be or can include products derived from natural starch, which has been converted by a physical, chemical, and/or physico-chemical treatment or by a biological treatment, for example an enzyme treatment, and derived or modified starches such as cationic, anionic, amphoteric, non-ionic or cross-linked starches and products resulting from starch hydrolysis, such as maltodextrins. In some embodiments, the modified starch can include a hydroxyalkylated starch, e.g., a hydroxypropylated or hydroxyethylated starch, a succinated starch, e.g., octenylsuccinated or dodecylsuccinated starch, a low amylose starch, and/or a waxy starch. The low amylose starch refers to starches that contain less than 40% by weight amylose. The waxy starch refers to starches that include a starch containing at least 95% by weight amylopectin. The modified starch can exhibit hydrophobicity, oleophobicity, or both.
In some embodiments, the styrene maleic anhydride can be or can include, but is not limited to, hydrolyzed copolymers of maleic anhydride and styrene, as well as salts (e.g., ammonium, potassium, and/or sodium salts) of such copolymers. In some embodiments, the styrene maleic anhydride can be a solubilized styrene-maleic acid (also referred to as “SMA”) copolymer. The styrene/maleic acid copolymer can include about 50 wt % to about 80 wt % of styrene and about 50 wt % to about 20 wt % of maleic acid and can have a molecular weight of about 3,000 to about 300,000. This copolymer can be solubilized by forming its ammonium salt in any manner known to the skilled practitioner. The styrene maleic anhydride can be in the form of a solution or a dispersion.
The ethylene acrylic acid dispersion can include an ethylene-acrylic acid copolymer. In some embodiments, the ethylene acrylic acid dispersion can be or can include S-1902-L ethylene-acrylic acid dispersion available from SNP, Inc.; AQUACER® 1055 available from BYK; the ethylene-acrylic acid copolymers sold under the name of ESCOR®, e.g., ESCOR® 5050, available from ExxonMobil; TWAX 7012 available from Tianshi.
In some embodiments, the polyvinyl alcohol can be in the form of a solution that includes partially hydrolyzed (at least about 87 percent) polyvinyl alcohol having a molecular weight of about 30,000 to about 50,000. In some embodiments, the polyvinyl alcohol can be or can include SELVOL® 205 available from Sekisui Specialty Chemicals America, LLC.
The ethylene vinyl alcohol is a copolymer of ethylene and vinyl alcohol. In some embodiments, the ethylene vinyl alcohol can be or can include, but is not limited to, one or more of the EVAL® ethylene vinyl alcohols available from Kuraray.
The fluorochemical compound can be or can include, but is not limited to, one or more anionic fluorochemicals, one or more cationic fluorochemicals, one or more amphoteric fluorochemicals, one or more non-ionic fluorochemicals, one or more polymeric fluorochemicals, one or more hybrid fluorochemicals, a fluorochemical allophanate, a fluorochemical polyacrylate, a fluorochemical urethane, a fluorochemical carbodiimide, a fluorochemical guanidine, or any mixture thereof. In some embodiments, the fluorochemical compound can exhibit a relatively strong hydrophobicity and a relatively low water solubility. As such, in some embodiments, to facilitate the use of the fluorochemical compound in an aqueous solvent system, the addition of ionic or hydrophilic groups or moieties (anionic, cationic, or nonionic) in the fluorochemical structure can be used to impart water solubility or water dispersibility.
In some embodiments, the fluorochemical compound can be or can include one or more perfluoroalkyl compounds and/or polyfluoroalkyl compounds. In some embodiments, the fluorochemical compound can include one or more of the fluorochemical compounds listed in Annex 2 as having a positive listing and authorized for use in imparting oil and grease resistance to paper products in OECD (2020), PFASs and Alternatives in Food Packaging (Paper and Paperboard) Report on the Commercial Availability and Current Uses, OECD Series on Risk Management, No. 58, Environment, Health and Safety, Environment Directorate, OECD. In some embodiments, the fluorochemical compound can be or can include the fluorochemical compounds commercially sold under the name ASAHIGUARD E-SERIES© available from AGC Chemicals Company.
The wax emulsion can be or can include any type of wax capable of imparting oil and grease resistance to the paper product. In some embodiments, the wax emulsion can be aqueous based. In some embodiments, the wax can be or can include, but is not limited to, paraffin wax, an ethylene bis(stearamide) wax, a polyethylene wax, a soy based wax, sunflower wax, carnauba wax, a fatty amine wax, or any mixture thereof. In some embodiments, the wax can be emulsified via the addition of one or more surfactants. The surfactant can be selected from any number of surfactants that can be used to emulsify two immiscible solutions. In some embodiments the surfactant can be a nonionic surfactant. For example, the nonionic surfactant can be a sorbitan surfactant such as SPAN™ 80, SPAN™ 85, SPAN™ 65, SPAN™ 60, SPAN™ 40, SPAN™ 20, TWEEN® 80, TWEEN® 40, TWEEN® 20, TWEEN® 21, TWEEN® 60, Triton-X® 100, or any mixture thereof.
The sizing composition and the barrier compound can also be used in conjunction with or serially with other additives conventionally used in the production of paper and other cellulosic products. Such additional additives conventionally used can be or can include, but are not limited to, colorants, inorganic pigments, fillers, anti-curl agents, surfactants, plasticizers, humectants, defoamers, UV absorbers, light fastness enhancers, polymeric dispersants, dye mordants, optical brighteners, leveling agents, and the like. All types of pigments and fillers can be added to the paper product. Such materials include, but are not limited to, clay, talc, titanium dioxide, calcium carbonate, calcium sulfate, and diatomaceous earths. Other additives, including, for example, alum, as well as other sizing agents, may also be used in the manufacture of paper products.
In some embodiments, the sizing composition can be used in combination with one or more materials that are cationic in nature or capable of ionizing or dissociating in such a manner as to produce one or more cations or other positively charged moieties. Such cationic agents can improve or otherwise aid in the retention of the sizing compositions on the plurality of fibers. In some embodiments, the material that can be used as the cationic agent can be or can include, but are not limited to, alum, aluminum chloride, long chain fatty amines, sodium aluminate, substituted polyacrylamide, chromic sulfate, animal glue, cationic thermosetting resins and polyamide polymers. Other suitable cationic agents can include cationic starch derivatives, including primary, secondary, tertiary, and/or quaternary amine starch derivatives and other cationic nitrogen substituted starch derivatives, as well as cationic sulfonium and phosphonium starch derivatives. Such derivatives can be prepared from all types of starches including corn, tapioca, potato, waxy maize, wheat, and rice. Moreover, such derivatives can be in their original granule form, or such derivatives can be converted to pregelatinized, cold water-soluble products and/or employed in liquid form. In some embodiments, the cationic agent can be added to the stock, i.e., the slurry, either prior to, along with, or after the addition of the sizing composition. In other embodiments, the cationic agent can be added to the stock, applied to the wet paper web, the wet paper sheet, the dried paper sheet, or a combination thereof.
If the cationic agent is used, the concentration of the cationic agent can vary depending, for example, on the particular sizing composition employed, the particular cationic agent employed, the particular pulp involved, the specific operating conditions, the contemplated end-use of the paper, and the like. Typical concentrations of the cationic agent can be from about 0.1 to about 5 parts per 1 part of the sizing composition.
In some embodiments, one or more sizing agents or compositions, in addition to the one or more alkenyl succinic anhydride compounds, can be used. In some embodiments, the additional sizing agent can be or can include, but is not limited to, a clay-based material, a rosin, a latex, a latex-based material, gelatin, an alkyl ketene dimer (AKD), a polyamide-epihalohydrin (PAE), a polyurethane, or any mixture thereof.
In some embodiments, the sizing compound can be added throughout the fiber slurry in as small a particle size as possible, preferably less than 2 microns. This can be achieved, for example, by emulsifying the sizing composition prior to addition to the stock utilizing mechanical means such as, for example, high speed agitators, mechanical homogenizers, and/or through the addition of a suitable emulsifying agent. Suitable emulsifying agents can be or can include, but are not limited to, cationic agents as described above, as well as non-cationic emulsifiers including, e.g., hydrocolloids such as ordinary starches, non-cationic starch derivatives, guar gums, dextrins, carboxymethyl cellulose, gum arabic, and/or gelatin, as well as various surfactants. Examples of suitable surfactants include, but are not limited to, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitol hexaoleate, polyoxyethylene sorbitol laurate, polyoxyethylene sorbitol oleate-laurate, sodium dioctyl sulfosuccinate, and polyoxyethylene alkyl phosphate. When such non-cationic emulsifiers are used, it can be desirable to separately add a cationic agent to the pulp slurry after the addition of the emulsified sizing agent. In preparing these emulsions with the use of an emulsifier, the latter can be first dispersed in water and the sizing composition can then be introduced along with vigorous agitation. Alternatively, the emulsification techniques described, for example, in U.S. Pat. No. 4,040,900, can be employed.
In order to provide a better understanding of the foregoing discussion, the following non-limiting examples are offered. Although the examples can be directed to specific embodiments, they are not to be viewed as limiting the invention in any specific respect. All parts, proportions, and percentages are by weight unless otherwise indicated.
The sizing agents used in the examples was cationic ULTRA-PHASE® G dispersed rosin size (available from Solenis Technologies) or NALSIZE® ONE LPB (available from Ecolab). The alkenyl succinic anhydride used in the examples was made by reacting maleic anhydride and 11-docosene (a symmetrical C22 internal olefin). The starch used in the examples was a standard size press starch.
Hand sheets were made and tested. The paper furnishes used to make the hand sheets that were tested was a mixture that included about 90 wt % of hardwood and about 10 wt % of softwood Kraft pulp mixture. The furnish was prepared by slushing dry lap, bleached hardwood, and softwood Kraft pulps. Both the hardwood and softwood pulps were refined in a Valley Beater until a freeness of about 300 ml Canadian Standard Freeness (CSF) was obtained. The final pulp mixture was diluted with tap water to a final consistency of about 1 wt % and brought to a pH of about 6 with sulfuric acid before use.
Hand sheets were prepared by mixing about 536 ml of an about 1 wt % consistency furnish at 1,000 RPM in a Dynamic Drainage Jar. The furnish aliquot was designed to produce a base sheet that had a basis weight of about 120 grams per square meter (gsm). At the start of mixing papermaker's alum was added. When the NALSIZE® ONE LPB was used to prepare the hand sheet, about 3.63 kg per 907 kg (about 8 lb/T) of alum was used. When ULTRAPHASE® G was used to prepare the hand sheet, about 7.26 kg 907 kg (about 16 lb/T) of alum was used. The sizing agent was added after about 15 seconds of mixing time. NALSIZE® ONE LPB was dosed at about 0.45 kg per 907 kg (about 1 lb/T), about 0.68 kg per 907 kg (about 1.5 lb/T), and about 0.91 kg per 907 kg (about 2 lb/T). Rosin was dosed at about 1.81 kg per 907 kg (about 4 lb/T), 2.72 kg per 907 kg (about 6 lb/T), and about 3.63 kg per 907 kg (about 8 lb/T). Starch was dosed along with the sizing agent after about 15 seconds of mixing at a dose of about 5.44 kg per 907 kg (about 12 lb/T). After about 30 seconds of mixing about 0.68 kg per 907 kg (about 1.5 lb/T) of NALCO© 7530 cationic flocculant was added. NALCO© 9000 (colloidal silica) was added after about 45 seconds of mixing at a dose of about 0.54 kg per 907 kg (about 1.2 lb/T). Mixing was stopped after about 60 seconds and the furnish was transferred to a Noble & Wood hand sheet mold deckle box.
The hand sheets were formed by drainage through a 100-mesh forming wire, which resulted in an about 20.3 cm×about 20.3 cm (about 8″×about 8″) hand sheet. The hand sheets were couched from the sheet mold wire by placing three blotters and a metal plate on the wet hand sheets and roll pressing with six passes of a metal roller that weighed about 11.34 kg (about 25 lb). The forming wire and one blotter were removed, and the hand sheet was placed between two new blotters and the press felt and pressed at about 345 kPa (about 50 psi) using the roll press. All the blotters were removed, and the hand sheet was dried (wire side facing the dryer surface) on a rotary drum drier set at a temperature of 104.4° C. (about 220° F.) for about 90 seconds in a single pass. After drying the hand sheets were placed in a constant temperature and humidity (CTH) room at a temperature of about 23° C. and about 50% relative humidity overnight to produce conditioned hand sheets before subsequent size testing. The average air-dry weight of the conditioned hand sheets was about 5.5 g, which corresponded to an average basis weight of about 128 gsm.
The conditioned hand sheets were coated with a size press starch or 63991 surface size chemistry. The 63991 surface size chemistry contained a styrene acrylate emulsion in combination with an alkyl ketene dimer. Coating was performed using a GARDCO® stainless steel applicator rod and glass plate. Various rods with different diameters and grooving were used to coat different thicknesses onto the hand sheets. Coated and uncoated hand sheets were then tested for sizing performance using the Hercules Sizing Tester (HST) (Tappi Method T 530 om-02). HST measurements were conducted using about 20% acid ink that had a reflectance endpoint of about 70%, as described in the Tappi method. Sizing was measured at two spots on the wire or coated side of each sheet and the average of the two measurements was reported.
In Example 1, the paper was treated with about 2.3 kg of the alkenyl succinic anhydride per 907 kg of the paper sheet. In Comparative Example 1, the paper was treated with about 19 kg per 907 kg of the paper sheet with rosin. The sizing performance was measured on the paper sheets both before and after further treatment with about 9 kg of a size press starch per 907 kg of the paper sheet. The sizing performance of the paper sheets are shown in Table 1.
As shown in Table 1, prior to the addition of the size press starch, rosin was able to achieve a HST value of about 100 s at a dose of about 19 kg per 907 kg of the paper sheet. An HST value of about 110 s was achieved by dosing about 2.3 kg of the alkenyl succinic anhydride per 907 kg of the paper sheet. After the addition of the same amount (about 9 kg per 907 kg of the paper sheet) of the size press starch it was observed that the sizing performance gain was significantly higher for the alkenyl succinic anhydride treated paper sheets compared to paper sheets treated with the rosin although the initial pre-size press sizing performance was similar for both examples. This result suggests that the alkenyl succinic anhydride has the potential to enhance surface properties of the paper sheet to optimize performance of size press formulations.
Sizing performance (HST) tests on folding carton grade paper hand sheets were carried out. The folding carton grade paper hand sheets were made as described above for the hand sheets used in Ex. 1 and CEx. 1. In Example 2, the folding carton grade paper hand sheet was treated with about 1.2 kg of the alkenyl succinic anhydride per 907 kg of the folding carton grade paper. In Comparative Example 2, the folding carton grade paper hand sheet was treated with about 3.6 kg of the rosin per 907 kg of the folding carbon grade paper. The treated folding carton grade paper hand sheets were also treated with about 7.3 kg of the size press starch per 907 kg of the folding carton grade papers or about 1.2 kg of a barrier compound. The barrier compound was a styrene acrylate emulsion (Acrylux SBMP acquired from Lumen Quimica). The sizing performance of the folding carton grade papers were tested after treatment with the sizing composition and were also tested after the addition of the size press starch or the barrier compound. After treating the hand sheets with the size press starch, the hand sheets were passed through a drum dryer (single pass) at 220° F. for 90 seconds. Hand sheets that were coated with the barrier chemistry were air dried and then set in a 125° C. oven for 5 minutes and then removed and equilibrated at room temperature. The sizing performance of the folding carton grade papers are shown in Table 2 below.
Table 2 shows that 1.2 kg of the alkenyl succinic anhydride per 907 kg of the folding carton grade paper achieved a pre-size press HST value of 20.2 s and 3.6 kg of rosin per 907 kg of the folding carton grade paper achieved a HST value of 13.4 s. After coating the size press starch onto the folding carton grade sheet, the HST value increased for both examples. The increase for the folding carton grade sheet treated with the alkenyl succinic anhydride was greater than the one treated with rosin. This may be due to the slightly higher initial sizing performance. After coating the barrier compound onto the folding carton grade papers that had been treated with the sizing composition (alkenyl succinic anhydride or rosin), the alkenyl succinic anhydride treated sheet had a significantly enhanced sizing performance as compared to rosin treated sheet.
An additional study was carried out to determine the ability of the alkenyl succinic anhydride to improve oil and grease resistance of a paper sheet. The paper sheets were made as described above for the hand sheets used in Ex. 1 and CEx. 1. In Example 3, the blank sheet was coated with about 0.45 kg of the alkenyl succinic anhydride per 907 kg of the blank sheet. In Example 4, the blank sheet was coated with about 0.9 kg of the alkenyl succinic anhydride per 907 kg of the blank sheet. In Comparative Example 3, the blank sheet was coated with about 2.7 kg of the rosin per 907 kg of the blank sheet. In Comparative Example 4, the blank sheet was coated with about 3.6 kg of the rosin per 907 kg of the blank sheet. The average KIT value for the blank sheet and the sheets coated with the alkenyl succinic anhydride or the rosin were measured and the values are shown in Table 3. The sheets were also further coated with PROTEAN® OGR (available from HS Manufacturing Group) as a barrier compound to provide oil and grease resistance. Once coated with the barrier compound the paper sheets were dried in an oven at a temperature of about 125° C. for about 5 minutes. None of the paper sheets in Table 3 were coated with size press starch. The average KIT values and the amount of the barrier compound applied to the sheets are also shown in Table 3. The average KIT values were the average of five (5) specimens, as measured according to the Grease Resistance Test for Paper and Paperboard T 559 pm-96 test method.
As shown in Table 3, prior to coating the sheets with the barrier compound, the blank sheet and those sized with the alkenyl succinic anhydride or the low dosing amount of rosin (CEx. 3) did not provide any oil/grease resistance as the KIT values were 1, which is the lowest value. When about 3.6 kg of the rosin per 907 kg of the paper sheet was applied (CEx. 4) the average KIT value was slightly higher at 2.
As also shown in Table 3, an average KIT value of up to 5 could be achieved by coating upwards of about 4.2 g/m2 to about 4.75 g/m2 of the barrier compound (blank coated with the barrier compound). This demonstrates the ability to achieve oil and grease resistance via the barrier compound alone at a relatively heavy coating weight. At a common dosage of about 3.6 g/m2 to about 3.7 g/m2, the sheets sized with rosin (CEx. 3 and 4) and the low dosage amount of the alkenyl succinic anhydride (Ex. 3) did not enhance the performance of the barrier compound as compared to the barrier compound alone at the relatively high coating weight. As the dosage amount of the alkenyl succinic anhydride increased from 0.45 kg to 0.9 kg per 907 kg of the blank sheet, the performance of the barrier compound was enhanced. More particularly, when the amount of alkenyl succinic anhydride was increased (Ex. 4), an average KIT value of up to 9 was achieved at a barrier compound dosage amount of only 3.35 g/m2. This was not only a surprising and unexpected improvement in the oil and grease resistance, but such improvement was obtained at a significantly lower dosage amount of the barrier compound.
With regard to Ex. 4, it is noted that the KIT value decreased for the hand sheet that had 3.6 g/m2 of the barrier compound as compared to when it had 3.35 g/m2 of the barrier compound. It was expected that the KIT value would increase with an increased amount of the barrier compound. Without wishing to be bound by theory, it is believed that the coating may have been unevenly applied meaning that certain areas of the sheet may have had a thicker coating and other areas may have had a thinner coating that could have led to the results shown in Table 3. For example, in Ex. 4 an area that had a thicker coating could have been measured for the hand sheet that included 3.35 g/m2 of the barrier compound and/or an area that had a thinner coating could have been measured for the hand sheet that included 3.6 g/m2 of the barrier compound.
Embodiments of the present disclosure further relate to any one or more of the following paragraphs:
Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, and/or the combination of any two upper values are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values are “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.
Various terms have been defined above. To the extent a term used in a claim is not defined above, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Furthermore, all patents, test procedures, and other documents cited in this application are fully incorporated by reference to the extent such disclosure is not inconsistent with this application and for all jurisdictions in which such incorporation is permitted.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims priority to U.S. Provisional Patent Application No. 63/415,170, filed on Oct. 11, 2022, which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 63415170 | Oct 2022 | US |
