Oil resistant sheet product

Abstract

A low grammage oil resistant article is formed from a coated basesheet containing fibers having a relatively high surface free energy. The basesheet can have a relatively low basis weight and the coating applied to the basesheet can be formed from a bio-based polymer. The article displays excellent oil and grease resistance without containing any fluorocarbon polymers.

Description

Attorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) OIL RESISTANT SHEET PRODUCT CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application is related and has right of priority to U.S. Provisional Patent Application No.63 / 500,333 filed on May 5, 2023, which is incorporated by reference in its entireties for all purposes. BACKGROUND

[0002] A variety of mechanical and chemical treatments are used in the papermaking industry to impart various properties to the finished paper. Resistance to oil and / or grease penetration is a particularly desirable property for paper products used in many applications. For instance, grease and oil resistance is needed in flexible packaging for fatty or greasy materials, such as fatty or greasy food products. Grease and oil resistant papers are also needed for other food containers, release liners, labels, pet food containers, and the like.

[0003] In the past, various chemicals have been incorporated into paper products in order to impart oil resistance. Conventionally, for instance, fluorocarbon compounds have been employed as surface sizes or coatings to impart oil penetration resistance. Fluorocarbons, in general, have very low surface energies and are not wet easily by oil-based materials. Although fluorocarbon compounds are well suited for providing oil resistance, recent government regulations have limited their use due to potential health, safety, and environmental concerns.

[0004] In addition to fluorocarbon compounds, various other chemicals and polymers have been suggested. For instance, silicone polymers and compounds have been used to coat papers in the past. Silicone, however, has various drawbacks and disadvantages. For instance, silicone can transfer to adjacent surfaces. Additionally, silicon coated papers are not recyclable.

[0005] U.S. Patent Publication No.2021 / 0348336, which is incorporated herein by reference, is directed to an oil resistant article in the form of a coated paper well suited for use as food packaging where oil and / or grease resistance is desired. The oil resistant article in the ‘336 publication can be produced without containing any fluorocarbon compounds. In this regard, the ‘336 application has providedAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) great advancements in the art. The present disclosure is directed to further improvements in producing oil and grease resistant articles, such as paper products. SUMMARY

[0006] In general, the present disclosure is directed to an oil resistant article. In accordance with the present disclosure, the oil resistant article can be made almost exclusively from recyclable materials and can be free or substantially free of fluorocarbon compounds. The oil resistant article can be made from a coated paper substrate. The construction of the paper layer in combination with one or more coating materials produces an article having excellent oil and / or grease resistance for use in all different types of applications, such as a food wrap.

[0007] For example, in one embodiment, the present disclosure is directed to an oil resistant article that includes a paper basesheet comprising pulp fibers. In accordance with the present disclosure, the pulp fibers can display a relatively low surface free energy which has been found to dramatically improve oil and grease resistance. For instance, the pulp fibers can display a surface free energy of less than about 39 mN / m, such as less than about 36 mN / m. In one aspect, the pulp fibers contain relatively great amounts of lignin. For instance, the pulp fibers can contain lignin in an amount greater than about 5% by weight, such as in an amount greater than about 10% by weight, such as in an amount greater than about 15% by weight, such as in an amount greater than about 20% by weight, and in an amount less than about 30% by weight. The basesheet can have a relatively low basis weight such as less than about 39 gsm, such as less than about 38 gsm, such as less than about 37 gsm, such as less than about 36 gsm, such as less than about 35 gsm, and greater than about 12 gsm, such as greater than about 16 gsm, such as greater than about 18 gsm.

[0008] An oil resistant coating is applied to at least one side of the basesheet. The oil resistant coating can comprise a bio-based polymer. As used herein, a “coating” refers to a film formed on the surface of a cellulose layer. A coating also can be described as cellulose layers that have been impregnated with a composition or coating material. As used herein, impregnation is one type of coating but can be distinguished from a surface coating, which is another type of coating. In one aspect, a coating can include impregnation in combination with aAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) surface coating

[0009] The oil resistant coating is present on the basesheet in relatively low amounts while still providing significant grease and oil resistant properties. For instance, the oil resistant coating can be applied to the basesheet in an amount less than about 5 gsm, such as in an amount less than about 4.5 gsm, such as in an amount less than about 4 gsm, and generally greater than about 0.5 gsm, such as greater than about 1.5 gsm. In one aspect, the oil resistant coating is applied to the basesheet so as to control a ratio between the weight of the oil resistant coating and the weight of the basesheet, called a saturation ratio. For instance, the oil resistant coating can be present on the basesheet such that the oil resistant article has a saturation ratio of from about 3% to about 20%, such as from about 5% to about 15%. In one aspect, the overall basis weight of the product can be less than about 45 gsm, such as less than about 43 gsm, such as less than about 42 gsm, such as less than about 40 gsm, such as less than about 38 gsm, such as less than about 36 gsm, and greater than about 14 gsm.

[0010] The oil resistant article and / or the oil resistant coating applied to the basesheet can be free or substantially free of fluorocarbon compounds. The oil resistant article also displays exceptional grease resistance. For instance, the oil resistant article can display a creased grease resistance of greater than about 70 min., such as greater than about 80 min., such as greater than about 90 min., such as greater than about 100 min., such as greater than about 110 min., such as greater than about 150 min., such as greater than about 200 min., such as greater than about 250 min., such as greater than about 300 min. when tested according to ISO Test 16532-1:2008.

[0011] The pulp fibers contained in the basesheet can comprise cellulosic fibers. The fibers can have a degree of refining (e.g. freeness value) of greater than about 60 °SR, such as greater than about 63 °SR, such as greater than about 70 °SR, such as greater than about 75 °SR, such as greater than about 80 °SR, and less than about 90 °SR, such as less than about 88 °SR. In one aspect, the basesheet contains unbleached cellulosic fibers, such as unbleached hardwood fibers. In one aspect, the basesheet can contain hardwood fibers in an amount greater than about50% by weight, such as greater than about 85% by weight.

[0012] In accordance with the present disclosure, an oil resistant coating isAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) located on at least one side of the basesheet. In one embodiment, for instance, an oil resistant coating can be applied to the first side and to the second side of the basesheet. In one aspect, the oil resistant article only includes one or more oil resistant coatings and does not contain any other coatings, such as water barrier coatings.

[0013] The oil resistant coating, as described above, can comprise a bio-based polymer. In one aspect, the oil resistant coating is made from a carboxymethyl cellulose. The carboxymethyl cellulose can have a viscosity of greater than about 100 cPs and less than about 2500 cPs when contained in a 10% aqueous solution at 60°C. Viscosity is measured with Brookfield RV viscosimeter at a speed of 100 rpm. In one aspect, the carboxymethyl cellulose is a sodium salt of a carboxymethyl cellulose.

[0014] In one aspect, the oil resistant coating comprises a carboxymethyl cellulose having a viscosity in a 10% aqueous solution of greater than about 200 cPs and less than about 2000 cPs, a purity of greater than about 93%, and is present on the basesheet in an amount of less than about 4.5 gsm and greater than about 0.5 gsm.

[0015] The oil resistant article of the present disclosure can be formed without incorporating any filler particles either into the basesheet or the oil resistant coating. Alternatively, some filler particles may be incorporated into the basesheet, such as in an amount less than about 10% by weight, such as in an amount less than 5% by weight. In addition, the oil resistant article can also be silicone free and can be produced without any acid treatment, such as used in producing parchment paper.

[0016] The oil resistant article can be made having various different permeability characteristics. In one aspect, for instance, the oil resistant article can have a Gurley permeability of greater than about 35,000 s / 100 mL. In another aspect, the oil resistant article can have a Gurley permeability of less than about 45,300 s / 100 mL and greater than about 5,000 s / 100 mL.

[0017] The oil resistant article can be calendered, but in one aspect is not calendered.

[0018] As described above, articles made in accordance with the present disclosure have excellent oil resistance. For instance, the article can have aAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) creased Kit oil rating of greater than about 3, such as greater than about 5, such as greater than about 6, such as greater than about 7, such as greater than about 8, such as greater than about 9, and less than about 12, such as less than about 11.

[0019] In another aspect, the present disclosure is directed to a process for producing the oil resistant article as described above. The process includes combining the pulp fibers with water to form an aqueous suspension of fibers. The aqueous suspension of fibers is deposited onto a porous forming surface to form the basesheet. An oil resistant composition is applied to at least one side, such as to two sides of the basesheet. The oil resistant composition contains the bio-based polymer. The oil resistant composition is then dried to form the oil resistant coating.

[0020] Other features and aspects of the present disclosure are discussed in greater detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] A full and enabling disclosure of the present disclosure is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which: Figure 1 is a cross-sectional view of one embodiment of an oil resistant article made in accordance with the present disclosure.

[0022] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention. DETAILED DESCRIPTION

[0023] It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present disclosure.

[0024] In general, the present disclosure is directed to an oil resistant article well suited for use in many and diverse applications. For example, the oil resistant article of the present disclosure can be in the form of a coated paper well suited for use as food packaging where oil and / or grease resistance is desired. Oil resistant articles in accordance with the present disclosure can also be used to replace wax coated paper in numerous applications. For example, the oil resistant article canAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) be used to produce labels, different types of food wraps, pet food packages, all different types of flexible packages, candy wraps, and oven sheets, such as microwave oven sheets. The oil resistant articles can also be used as cosmetics / hygiene wrapping materials for soaps including dishwashing soap, The oil resistant articles made in accordance with the present disclosure can also be used in the medical field as part of a patient care wrap or as a wrapping material for medical instruments and devices.

[0025] Oil resistant articles made in accordance with the present disclosure offer various different advantages and benefits. For example, the oil resistant articles and / or coatings incorporated into the articles can be produced without containing any fluorocarbon compounds. For instance, the article can contain fluorocarbon compounds and / or fluorine in an amount less than about 50 ppm, such as less than about 40 ppm, such as less than about 30 ppm, such as less than about 20 ppm, such as less than about 10 ppm, such as less than about 5 ppm, such as less than about 2 ppm. Articles made in accordance with the present disclosure can also be silicone-free and can be made without subjecting the product to any acid treatment such as in the production of parchment paper.

[0026] In order to produce oil resistant articles in accordance with the present disclosure, various different parameters and / or materials are selected, adjusted and controlled in order to produce articles with enhanced oil and grease resistance. For example, the type of fibers used to produce the article, the amount the fibers are refined, the type of bio-based polymer coating applied to the base web, and / or the amount of the bio-based polymer coating applied to the base web can all be controlled and adjusted for producing articles with dramatically better overall properties. For example, oil resistant articles are made according to the present disclosure containing cellulose fibers having a relatively low surface free energy. The fibers are also refined to a certain degree in order to obtain a freeness value. The resulting base web also has a relatively low basis weight and low permeability which has been found to actually improve oil and grease resistance. In addition, the amount of coating applied to the base web can be adjusted and controlled depending upon the weight of the web. All of these factors can be combined to produce the articles.

[0027] In addition, the oil resistant articles made in accordance with the presentAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) disclosure can have a relatively simple or elegant construction without containing multiple layers of paper or coatings. For instance, in one aspect, the oil resistant article of the present disclosure can contain a single paper layer combined with one or two coatings applied to at least one side of the paper substrate. In this manner, the resulting product has low stiffness properties and is easy to manipulate, such as when wrapping other products.

[0028] Referring to FIG.1, one embodiment of an oil resistant article generally 10 made in accordance with the present disclosure is shown. FIG.1 represents a cross-sectional view of the product 10. As shown, in this embodiment, the oil resistant article 10 includes a paper basesheet 12 formed from pulp fibers. The basesheet 12, for instance, can be a wetlaid paper layer. In other embodiments, however, the basesheet 12 can been air formed, foam formed or the like. The basesheet 12 includes a first surface opposite a second surface. Applied to the first surface of the basesheet 12 is an oil resistant coating 14 as shown in FIG.1. Applied to the second surface of the basesheet 12 is a second oil resistant coating 15. The oil resistant coatings 14 and 15 can appear as separate layers or can be applied so that they become impregnated in the basesheet 12. The oil resistant coatings 14 and 15 are formed from an oil resistant polymer. In accordance with the present disclosure, the oil resistant coatings 14 and 15 can be fluorine-free and can be made from a bio-based polymer. The bio-based polymer, for instance, can be derived from plant matter, such as cellulose. In one embodiment, for instance, the bio-based polymer can be a cellulose derivative, such as a carboxymethyl cellulose. Other bio-based polymers include starch and / or vegetable protein- based polymers, such as polymers derived from soy or other plants.

[0029] As shown in FIG.1, the oil resistant article 10 can be made exclusively from a single paper layer or basesheet 12 combined with the oil resistant coatings 14 and 15. In one aspect, the oil resistant article can only include a basesheet and one or more oil resistant coatings and can be free of other coatings, such as water resistant coatings. In fact, water resistant coatings may be undesirable in certain applications.

[0030] As described above, in one embodiment, the basesheet 12 is a wetlaid pulp fiber paper layer. The basesheet 12 can be formed from an aqueous suspension of cellulose fibers. In one embodiment, in forming the basesheet, theAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) aqueous suspension of fibers is deposited onto a porous forming surface (such as a flat wire) that allows water to drain thereby forming the basesheet. As the paper web is formed and dried, the paper can be gathered, crimped, embossed, and / or calendered.

[0031] The basesheet is primarily formed of pulp fibers. For instance, greater than about 90%, such as greater than about 95% by weight of the basesheet can comprise pulp fibers. In accordance with the present disclosure, in one embodiment, the cellulose fibers selected for use in constructing the basesheet have a relatively low surface free energy. The fibers, for instance, can be obtained or modified in a way that lowers the polar nature which has been found to increase grease and oil resistance. For instance, the cellulose fibers can have a surface free energy of less than about 39 mN / m, such as less than about 38 mN / m, such as less than about 37 mN / m, such as less than about 36 mN / m. The surface free energy is generally greater than about 20 mN / m. Surface free energy can be measured, for instance, using any suitable instrument, such as a surface analyzer commercially available from Kruss GmbH. Cellulose fibers having a relatively low surface free energy can be obtained in various ways. For example, the fibers can be treated with a chemical composition that can lower surface free energy. In one embodiment, the cellulose fibers can contain a relatively high amount of lignin. For instance, the cellulose fibers may contain lignin in an amount greater than about 5% by weight, such as in an amount greater than about 10% by weight, such as in an amount greater than about 15% by weight, such as in an amount greater than about 20% by weight, and in an amount less than about 30% by weight, such as in an amount less than about 25% by weight.

[0032] The basesheet of present disclosure can contain wood pulp, bast fibers and / or mixtures thereof. The wood pulp can be hardwood, softwood, or mixtures. The bast fibers can be flax, hemp, or mixtures. For instance, the base web can contain unbleached wood fibers in an amount greater than about 50% by weight, such as in an amount greater than about 60% by weight, such as in an amount greater than about 70% by weight, such as in an amount greater than about 80% by weight, such as in an amount greater than about 85% by weight, such as in an amount greater than about 90% by weight, such as in an amount greater than about 98% by weight.Attorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT)

[0033] In one aspect, the basesheet of the present disclosure primarily contains hardwood fibers. The hardwood fibers can be partially bleached fibers or unbleached fibers. In one aspect, the basesheet is formed from unbleached hardwood fibers. For instance, the base web can contain unbleached hardwood fibers in an amount greater than about 50% by weight, such as in an amount greater than about 60% by weight, such as in an amount greater than about 70% by weight, such as in an amount greater than about 80% by weight, such as in an amount greater than about 85% by weight, such as in an amount greater than about 90% by weight, such as in an amount greater than about 98% by weight.

[0034] The cellulose fibers pulp contained in the basesheet can have an average fiber length prior to refining of generally greater than about 0.2 mm, such as greater than about 0.5 mm, such as greater than about 0.7 mm, and less than about 3 mm, such as less than about 2 mm, such as less than about 1.7 mm, such as less than about 1.5 mm.

[0035] As described above, the cellulose fibers can comprise pulp fibers. The pulp fibers can also be subject to refining. Refining can be conducted using any suitable refining equipment or device. As used herein, the term “refined” is used to mean that the cellulose fibers are subjected to a mechanical treatment that modifies the fibers so as to cause fibrils to form. Refining can be accomplished using a conical refiner, a disc refiner, or a Valley beater. The mechanical process exerts an abrasive and bruising action on the cellulose fibers such that the cellulose fibers are deformed and declustered.

[0036] The level the pulp fibers have been refined is referred to as the freeness value. The freeness value (°SR) measures generally the rate at which a dilute suspension of refined fibers may be drained. The freeness is measured by the Schopper Riegler Method for drainability. As used herein, freeness is measured according to Test NORM EN ISO 5267-1. Pulp fibers used to construct the basesheet of the present disclosure, for instance, can have a degree of refining of greater than about 60 °SR, such as greater than about 63 °SR, such as greater than about 65 °SR. The cellulose fibers can have a degree of refining of less than about 95 °SR, such as less than about 90 °SR, such as less than about 87 °SR, such as less than about 85 °SR, such as less than about 83 °SR , such as less than about 80 °SR, such as less than about 78 °SR, such as less than about 75Attorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) °SR, such as less than about 73 °SR.

[0037] Basesheets made in accordance with the present disclosure generally have a relatively low basis weight. The basis weight of the basesheet (prior to applying any coatings) is generally less than than about 39 gsm, such as less than about 38 gsm, such as less than about 37 gsm, such as less than about 35 gsm, such as less than about 33 gsm. The basis weight of the basesheet is generally greater than about 12 gsm, such as greater than about 18 gsm, such as greater than about 20 gsm, such as greater than about 22 gsm, such as greater than about 25 gsm,such as greater than about 27 gsm, such as greater than about 30 gsm.

[0038] It was discovered that basesheets formed from fibers having a relatively low surface energy, having a degree of freeness as described above, having a relatively low basis weight as described above, and having a good structure that is well suited to synergistically accepting a coating formed from a bio-based polymer. Although unknown, it is believed that the bio-based polymer fills in and clogs substantially all of the voids or capillaries contained in the basesheet in a manner that does not occur at higher basis weights. Thus, it is believed that the lower basis weight basesheet in combination with the bio-based polymer coating contributes to the oil and grease resistant properties of the product.

[0039] In one aspect, basesheets made according to the present disclosure may be made without containing any filler particles. For example, the basesheets can be free of, calcium carbonate particles, magnesium oxide particles, or the like. Instead, the basesheet can be made from cellulose fibers alone or in combination with various chemical treatments.

[0040] Alternatively, filler particles can be incorporated into the basesheet. The filler particles can be titanium oxide particles, calcium carbonate particles, magnesium oxide particles, or mixtures thereof. The filler particles can be present in the basesheet in an amount less than about 10% by weight, such as in an amount of less than about 5% by weight, such as in an amount less than about 3% by weight, and generally in an amount greater than about 0.5% by weight, such as in an amount greater than 2.5% by weight.

[0041] Chemical treatments that can be applied to the basesheet and / or incorporated into the basesheet include binders, sizing agents, and / or wet strengthAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) agents. For example, in one embodiment, a binder can be incorporated into the basesheet that helps increase integrity, increase oil resistance and / or increase runnability. The binder can comprise any suitable polymer, such as a film-forming thermoplastic polymer. In one aspect, the binder is a natural polymer obtained directly or derived from natural ingredients, such as plants. The binder, for instance, can be a cellulose derivative, guar gum, pectin, starch, mixtures thereof or the like. Binders can be applied to the basesheet at the wet end of the process if the basesheet is formed through a wetlaid process. For instance, the binder can be incorporated into the fiber furnish prior to being deposited onto a forming surface or applied prior to drying. In one aspect, a cellulose derivative binder, such as a carboxymethyl cellulose can be incorporated into the basesheet. The carboxymethyl cellulose can be combined with the pulp fibers in relatively small amounts. For instance, the carboxymethyl cellulose binder can be added to the basesheet in an amount less than about 2% by weight, such as in an amount less than about 1.5% by weight, such as in an amount less than about 1% by weight, such as in an amount less than about 0.5% by weight. The carboxymethyl cellulose binder can be present in the basesheet in an amount greater than about 0.005% by weight, such as in an amount greater than about 0.08% by weight, such as in an amount greater than about 0.1% by weight.

[0042] In one embodiment, the binder incorporated into the basesheet is a starch, such as a cationic starch. The starch can be added to the pulp fibers alone or in combination with other binders, such as the carboxymethyl cellulose binder as described above. The starch can be added to the basesheet generally in an amount greater than about 0.005% by weight, such as in an amount greater than about 0.1% by weight, such as in an amount greater than about 0.5% by weight, such as in an amount greater than about 1% by weight. The starch can be added to the basesheet in an amount less than about 5% by weight, such as in an amount less than about 4% by weight, such as in an amount less than about 3% by weight, such as in an amount less than about 2% by weight, such as in an amount less than about 1% by weight. In one particular embodiment, for example, a cationic starch can be incorporated into the basesheet in an amount from about 1% to about 2% by weight.

[0043] In one embodiment, the basesheet contains a carboxymethyl celluloseAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) binder and a starch binder as described above.

[0044] In addition to one or more binders, a sizing agent can also be incorporated into the basesheet. The sizing agent is also applied at the wet end of the papermaking process. Applying a sizing agent to the basesheet can improve the integrity of the basesheet and improve the liquid repellant properties. In one embodiment, the sizing agent applied to the basesheet is an alkyl-ketene dimer or rosin or alkenyl succinic anhydride. The amount of sizing agent added to the basesheet during formation of the basesheet can be from about 0.01% to about 0.3% by weight, preferably from about 0.1% to about 0.2% by weight.

[0045] Still another chemical component that can be incorporated into the basesheet is a wet strength agent. A wet strength agent may reduce the potential for degradation of the basesheet if the latter is placed in contact with a liquid, such as water. Typically, the wet strength agent may be chosen from polyamides, such as epichlorohydrin resin, a polyamine-epichlorohydrin resin, a poly(aminoamide)- epichlorohydrin resin; an alkylsuccinic anhydride; a polyvinylamine; an oxidized polysaccharide. Typically, the amount of wet strength agentiadded in the wet end of the process is from 0.01% to 2%, preferably from 0.1% to 1.5% by weight.

[0046] As shown in FIG.1, in addition to the basesheet 12, the oil resistant article of the present disclosure further includes at least one oil resistant coating applied to one surface of the basesheet, such as to both sides of the basesheet. The oil resistant coating is formed from an oil resistant polymer. In one aspect, the oil resistant coating is formed from a bio-based polymer. In fact, in one embodiment, the coating is made entirely from bio-based materials. The bio- based polymer, in one embodiment, can be a film-forming polymer. Particular examples of oil resistant polymers that may be used to form the coating include a cellulose derivative, a starch, an alginate,vegetable protein-based polymer or mixtures thereof. Of particular advantage, the oil resistant coating can be formed exclusively from one or more oil resistant polymers without having to incorporate filler particles into the coating.

[0047] In one embodiment, the oil resistant coating is formed from a carboxymethyl cellulose polymer. In one aspect, a carboxymethyl cellulose polymer can be selected that has a relatively high purity. Suitable purity ranges are from 85 % to 98%, preferably from 90% to 97% and even more preferably fromAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) 93% to 95% of a CMC salt. Suitable carboxymethyl cellulose compositions are commercially available. In one aspect, the carboxymethyl cellulose polymer has a viscosity when measured in a 10% aqueous solution at 60°C using a 100 rpm Brookfield viscometer of greater than about 50 cP, such as greater than about 200 cP, such as greater than about 500 cP and less than about 2500 cP, such as less than about 2000 cP, such as less than about 1500 cP, such as less than about 1000 cP, such as less than about 800 cP.

[0048] The viscosity of polymer materials disclosed herein including the carboxymethyl cellulose polymer can be measured according to test DIN 53019.

[0049] In one aspect, the carboxymethyl cellulose incorporated into the oil resistant coating can an oxidated carboxymethyl cellulose. The carboxymethyl cellulose may be used in a highly-purified, cold water-soluble form.

[0050] In one aspect, the carboxymethyl cellulose used to form the oil resistant coating comprises a sodium carboxymethyl cellulose. The sodium carboxymethyl cellulose is an anionic polymer that is water soluble and that can have a degree of substitution of from about 0.4 to about 0.7, including all increments of 0.1 therebetween. The sodium carboxymethyl cellulose can have a purity of greater than about 60%, such as greater than about 70%, such as greater than about 80%, such as greater than about 90%.

[0051] In another embodiment, the oil resistant coating can be formed from a starch. Any suitable starch can be applied to one or more surfaces of the basesheet. In one aspect, the starch is a modified corn, potato or pea starch having a relatively low viscosity. For example, the starch can have a viscosity at 10 % of solids at 50°C of from about 10 cPs to about 60 cPs, such as from about 20 cPs to about 50 cPs. The starch can be derived from a starch source having at least 90 percent amylopectin.

[0052] In still another embodiment, the oil resistant coating can be formed from a vegetable protein-based polymer. The preferred vegetable protein is a soy protein. These materials are built up of a group of about 25 amino acids and derived from processing of soybeans. The protein is derived by removing the oil and hull and processing the soybean. These materials are reduced in size and extracted with an alkaline solution isolating the soy protein in its native form along with low molecular weight sugars. The protein material can be hydrolyzed at highAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) pH and reflux conditions to break the protein into smaller units. The protein is amphoteric having cationic and anionic reactive sites. The combination of hydrophobic and charged regions maintains the globular protein subunits and makes them self-associating. Hydrolization under alkaline conditions causes the protein to unfold and re-associate by hydrophobic and hydrophillic regions. Under hydrolysis conditions, hydrophilic anionic groups are more exposed reducing solution viscosity. Optionally the soy protein can be further modified by carboxylating the protein yielding a soy protein of reduced viscosity. Preferred vegetable proteins herein have a specific gravity ranging from about 1.007 at a solids content in solution of 5% by weight (30°C) to about 1.05 at 20% solids content (TAPPI TISIO 104-01 Technical Information Sheet). The bulk dry specific gravity is higher. The preferred soy protein herein has a specific gravity dry of about 1.38. One vegetable protein herein is a hydrolyzed amphoteric soybean protein. This material is hydrolyzed as a 13.5% solids solution in a solution of ammonium hydroxide to yield a solution pH of about 9-10.4. Thereafter the material is acidified. The preferred hydrolyzed amphoteric soybean protein has a pH as a 15% slurry around 4.0 to 4.5. The protein is then typically isolated and stored as a dry flake or powder.

[0053] The oil resistant coating is applied to the basesheet in an amount sufficient to provide the necessary oil resistant properties. It was discovered that the oil resistant coating can have a relatively low basis weight and still provide the desired oil and grease resistant properties. In particular, it is believed that the oil resistant coating synergistically functions with the lower surface free energy fibers and the relatively low basis weight basesheet to form an impenetrable oil and grease resistance layer. For instance, the oil resistance coating can have a basis weight of less than about 5 gsm, such as less than about 4.8 gsm, such as less than about 4.5 gsm, such as less than about 4.3 gsm, such as less than about 4 gsm, such as less than about 3.8 gsm, such as less than about 3.5 gsm, such as less than about 3.3 gsm, such as less than about 3.1 gsm, such as less than about 2.9 gsm, such as less than about 2.7 gsm, such as less than about 2.5 gsm. The basis weight of the oil resistant coating is generally greater than about 0.5 gsm, such as greater than about 1 gsm, such as greater than about 1.5 gsm, such as greater than about 2 gsm, such as greater than about 2.5 gsm.Attorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT)

[0054] In one aspect, the weight of the oil resistant coating can be controlled in relation to the weight of the basesheet. For instance, an oil coating saturation ratio is the ratio between the basis weight of the coating to the basis weight of the basesheet. In one aspect, the oil resistant coating is applied to the basesheet in order to obtain a saturation ratio of from about 3% to about 20%, including all increments of 0.1% therebetween. In one aspect, it was discovered that improved oil and grease resistance were found when the saturation ratio was greater than about 5%, such as greater than about 6%, such as greater than about 6.2%, such as greater than about 6.4%, such as greater than about 6.6%, such as greater than about 6.8%, such as greater than about 7%, such as greater than about 7.2%, such as greater than about 7.4%, such as greater than about 7.6%, such as greater than about 7.8%, such as greater than about 8%. The saturation ratio, in one aspect, can be less than about 17%, such as less than about 15%, such as less than about 13%, such as less than about 10%, such as less than about 9%, such as less than about 8%.

[0055] The oil resistant coating can be applied to the basesheet using any suitable method or technique. In one aspect, for instance, the oil resistant coating can be applied to the basesheet using a size press. By using a size press, the oil resistant article of the present disclosure can be produced in a single process. Alternatively, however, the basesheet can first be formed and later coated with the oil resistant coating. Methods for applying the oil resistant coating include film press, air knife coating, bar coating, blade coating, gravure printing, slot die coating, curtain coating, and the like.

[0056] After the oil resistant coating is formed on the basesheet, in one embodiment, the resulting article can be calendered if desired. In one aspect, the basesheet can be calendered prior to applying the oil resistant coating. In another aspect, the article is not calendered.

[0057] Oil resistant articles of the present disclosure can be produced in a manner that controls the permeability characteristics of the final product. For instance, oil resistant articles made according to the present disclosure can have a high permeability or a low permeability. Permeability can be measured according to the Gurley Test, using a Gurley permeability tester, such as Gurley Model 4340. The test can be conducted according to ISO Test 5636-5:2003. The Gurley TestAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) measures air permeability as a function of the time required for a specified amount of air to pass through a specified area of the product under a specified pressure. The units are reported in seconds per 100 mL. Lower numbers, therefore, can represent substrates with more openness or higher permeability. Oil resistant articles can be made according to the present disclosure having a Gurley permeability of less than about 45,200 s / 100 mL, such as less than about 40,000 s / 100 mL, such as less than about 35,000 s / 100 mL, such as less than about 30,000 s / 100 mL, and generally greater than about 3,000 s / 100 mL, such as greater than about 5,000 s / 100 mL, such as greater than about 8,000 s / 100 mL. The Gurley permeability of oil resistant articles made according to the present disclosure can also be relatively high, such as greater than about 20,000 s / 100 mL, such as greater than about 25,000 s / 100 mL, such as greater than about 30,000 s / 100 mL, such as greater than about 35,000 s / 100 mL, such as greater than about 40,000 s / 100 mL.

[0058] As described above, products made according to the present disclosure have excellent oil and grease resistant properties. The oil and grease resistance properties are dramatic in view of the small amount of materials used to produce the products.

[0059] One method to measure grease resistance is a grease migration test according to ISO Test 16532-1:2008. The grease migration test can be measured on a flat substrate or on a substrate that has been creased. Demonstrating grease resistance when creased can be very difficult. Many substrates that are grease resistant when flat can experience significant degradation of the grease resistant properties when creased.

[0060] Oil resistant articles made according to the present disclosure can display a flat grease resistance of greater than about 40 min., such as greater than about 60 min., such as greater than about 80 min., such as greater than about 100 min., such as greater than about 120 min., such as greater than about 140 min., such as greater than about 160 min., such as greater than about 180 min., such as greater than about 200 min. In other embodiments, the flat grease resistance can be greater than about 300 min., such as greater than about 400 min., such as greater than about 500 min., such as greater than about 600 min., such as greater than about 700 min., such as greater than about 800 min. The flat greaseAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) resistance can be less than about 10,000 min.

[0061] Remarkably, products made according to the present disclosure can also display excellent grease resistance when creased. For instance, the creased grease resistance of oil resistant articles made according to the present disclosure can be greater than about 60 min., such as greater than about 70 min., such as greater than about 80 min., such as greater than about 90 min., such as greater than about 100 min., such as greater than about 110 min., such as greater than about 120 min., such as greater than about 150 min., such as greater than about 200 min., such as greater than about 250 min., such as greater than about 300 min. and less than about 2,000 min.

[0062] Oil resistance can be measured using a Kit oil test. The Kit oil test, for instance, can be measured using TAPPI Test Method T 559 cm-02 (2002). To measure oil resistance using the Kit oil test, 12 test solutions containing different mixtures of toluene, n-heptane, and castor oil are premixed.

[0063] Each Kit oil is dropped on the substrate to be tested. When any dark spot is formed, the oil resistance is unacceptable. When no spot is formed, the oil resistance is evaluated as acceptable. The oil resistance is expressed in terms of the maximum Kit solution for which the oil resistance is acceptable. The larger the number of mixed solvent, the better the oil resistance of the paper. Oil resistant articles made according to the present disclosure can have a flat Kit oil test rating of generally greater than 3, such as greater than 4, such as greater than 5, such as greater than 6, such as greater than 7, such as greater than 8. The Kit oil test rating is generally less than 12, such as less than 11. The oil resistant articles can display a creased Kit oil test rating of also greater than 3, such as greater than 4, such as greater than 5, such as greater than 6, such as greater than 7, such as greater than about 8, such as greater than about 9, and less than 12.

[0064] The above results are dramatic considering that the oil resistant article of the present disclosure is made with recyclable materials. For instance, the oil resistant article is repulpable. Further, the oil resistant article can be formed without containing any fluorocarbon compounds or silicone compounds.

[0065] The present disclosure is embodied by various embodiments. In one embodiment, the present disclosure is directed to an oil resistant article comprising a paper basesheet comprising pulp fibers. The pulp fibers can contain lignin in anAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) amount of at least about 5% by weight and the basesheet can have a basis weight of from about 14 gsm to less than about 38 gsm. An oil resistant coating is applied to at least one side of the basesheet, such as to both sides of the basesheet. The oil resistant coating can comprise a bio-based polymer and can be present on the basesheet in an amount of less than about 5 gsm. The oil resistant coating is free of fluorocarbon compounds. The oil resistant article can display a creased grease resistance of greater than 70 min. when tested according to ISO Test 16532- 1:2008.

[0066] The oil resistant article as described above can display a creased grease resistance of greater than about 90 min., such as greater than about 110 min., such as greater than about 150 min., such as greater than about 200 min., such as greater than about 250 min., such as greater than about 300 min. when tested according to ISO Test 16532-1:2008.

[0067] In one aspect, the pulp fibers contain lignin in an amount greater than about 10% by weight, such as in an amount of greater than about 15% by weight, such as in an amount of greater than about 20% by weight, and in an amount of less than about 30% by weight.

[0068] In one aspect, the pulp fibers display a low surface free energy such as less than about 39 mN / m, such as less than about 36 mN / m. The pulp fibers can comprise unbleached cellulosic fibers comprising wood or bast fibers, such as unbleached hardwood fibers.

[0069] In one aspect, the oil resistant article further comprises a sizing agent present in the basesheet. The sizing agent can comprise a ketene dimer. The sizing agent can comprise an alkyl ketene dimer. The oil resistant article as described above can display a creased grease resistance of greater than about 90 min., such as greater than about 110 min., such as greater than about 150 min., such as greater than about 200 min., such as greater than about 250 min., such as greater than about 300 min. when tested according to ISO Test 16532-1:2008.

[0070] The oil resistant article as described above, can contain pulp fibers having a degree of refining of greater than about 60 °SR, such as greater than about 62 °SR, such as greater than about 70 °SR, such as greater than about 80 °SR and less than about 90 °SR.

[0071] In one aspect, the oil resistant article as described above containsAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) hardwood fibers in an amount of greater than about 50% by weight, such as in an amount of greater than about 60% by weight, such as in an amount greater than about 80% by weight.The oil resistant coating can comprise a carboxymethyl cellulose. In one aspect, the oil resistant coating comprises a sodium salt of a carboxymethyl cellulose. In one aspect, the carboxymethyl cellulose can have a viscosity in a 10% aqueous solution of greater than about 50 cPs and less than about 2500 cPs. In one aspect, the carboxymethyl cellulose can have a viscosity of greater than about 200 cPs and less than about 2000 cPs, such as greater than about 500 cPs and less than about 1500 cPs, and can have a purity of greater than about 93%, such as greater than about 95%. In one aspect, the oil resistant coating comprised of carboxymethyl cellulose as described above is present on the basesheet in an amount of less than about 4.5 gsm, such as less than about 4 gsm and greater than about 0.5 gsm, such as greater than about 1.5 gsm.

[0072] The present disclosure may be better understood with reference to the following example. Example

[0073] Various different oil resistant articles were made and compared to a fluorocarbon polymer coated commercial product. The following samples were tested: Sample No.1: Basesheet containing unbleached hardwood fibers having a refining degree of 87°SR, 0.2% of alkyl-ketene dimer and having a basis weight of 29 gsm and coated via size-press with a sodium carboxymethyl cellulose (dry coating weight is 1.9 + / -0.1 gsm). Sample No.2: Basesheet containing unbleached hardwood fibers having a refining degree of 87°SR, 0.1% of alkyl-ketene dimer and having a basis weight of 32 gsm and coated via size-press with a sodium carboxymethyl cellulose (dry coating weight is 1.9 + / -0.1 gsm). Sample No.3: Basesheet containing unbleached hardwood fibers having a refining degree of 85°SR, 0.1% of alkyl-ketene dimer and having a basis weight of 38 gsm and coated via size-press with a sodium carboxymethyl cellulose (dryAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) coating weight from 2.1 + / - 0.1 gsm). Sample No.4: Basesheet containing bleached hardwood having a refining degree of 89°SR, 0.1% of alkyl-ketene dimer and fibers having a basis weight of 35 gsm and coated via size-press with a low viscosity sodium carboxymethyl cellulose (dry coating weight from 2 + / -0.1 gsm). Sample No.5: Basesheet containing bleached hardwood fibers having a refining degree of 80°SR, 0% of alkyl-ketene dimer and having a basis weight of 40 gsm and coated via size-press with a fluorocarbon polymer, namely PFPE at a level of 0.14% w / w.

[0074] Sample Nos.1, 2 and 3 above were made from fibers having a relatively high lignin content and a relatively low surface free energy. The hardwood fibers used to form the basesheets were unbleached. Sample No.4 and 5, on the other hand, contained hardwood fibers having a lower lignin content that were bleached.

[0075] Each sample was tested for porosity and oil resistance to various compositions. The following results were obtained: Sample Sample Sample Sample Analysis Sample No.4 No 1 No 2 No 3 No 5 l ed

[0076] As shown, Sample No.1 and 2 displayed dramatically better creased oil resistance than the other samples. The above results also demonstrate that atAttorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) lower basis weights, the oil resistant coating operates synergistically with the basesheet to produce an oil and grease resistant article.

[0077] These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only and is not intended to limit the invention so further described in such appended claims.

Claims

Attorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) What Is Claimed:

1. An oil resistant article comprising: a paper basesheet comprising pulp fibers, the pulp fibers containing lignin in an amount of at least about 5% by weight, the basesheet having a basis weight of from about 14 gsm to less than about 39 gsm, the basesheet including a first side and a second and opposite side; an oil resistant coating on at least one side of the basesheet, the oil resistant coating comprising a bio-based polymer, the oil resistant coating being present on the basesheet in an amount of less than about 5 gsm; and wherein the oil resistant coating is free of fluorocarbon compounds and wherein the oil resistant article displays a creased grease resistance of greater than 70 min. when tested according to ISO Test 16532-1:2008.

2. An oil resistant article as defined in claim 1, wherein the pulp fibers contain lignin in an amount greater than about 10% by weight and in an amount less than about 30% by weight.

3. An oil resistant article as defined in claim 1, wherein the oil resistant coating is present on the basesheet such that the oil resistant article has a saturation ratio of from about 3% to about 20%.

4. An oil resistant article as defined in claim 1, wherein the pulp fibers display a surface free energy of less than about 39 mN / m.

5. An oil resistant article as defined in claim 1, wherein the oil resistant article further comprises a sizing agent present in the basesheet.

6. An oil resistant article as defined in claim 5, wherein the sizing agent comprises a ketene dimer.

7. An oil resistant article as defined in claim 5, wherein the sizing agent comprises an alkyl ketene dimer.

8. An oil resistant article as defined in claim 1, wherein the oil resistant article further comprises a binder present in the basesheet.

9. An oil resistant article as defined in claim 8, wherein the binder comprises a carboxymethyl cellulose.

10. An oil resistant article as defined in claim 1, wherein the oil resistant article displays a creased grease resistance of greater than about 90 min. when tested according to ISO Test 16532-1:2008.Attorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) 11. An oil resistant article as defined in claim 1, wherein the pulp fibers contained in the basesheet have a degree of refining of greater than about 60 °SR.

12. An oil resistant article as defined in claim 1, wherein the pulp fibers contained in the basesheet have a degree of refining of greater than about 80 °SR and less than about 90 °SR.

13. An oil resistant article as defined in claim 1, wherein the basesheet comprises unbleached cellulosic fibers comprising wood or bast fibers.

14. An oil resistant article as defined in claim 1, wherein the basesheet comprises unbleached hardwood fibers.

15. An oil resistant article as defined in claim 1, wherein the basesheet contains hardwood fibers in an amount of greater than about 50% by weight.

16. An oil resistant article as defined in claim 1, wherein the oil resistant coating comprises a carboxymethyl cellulose.

17. An oil resistant article as defined in claim 1, wherein the oil resistant coating comprises a sodium salt of a carboxymethyl cellulose.

18. An oil resistant article as defined in claim 17, wherein the carboxymethyl cellulose has a viscosity in a 10% aqueous solution of greater than about 50 cPs and less than about 2500 cPs.

19. An oil resistant article as defined in claim 1, wherein the oil resistant coating is present on the basesheet in an amount of less than about 4.5 gsm and greater than about 0.5 gsm.

20. An oil resistant article as defined in claim 16, wherein the carboxymethyl cellulose has a viscosity in a 10% aqueous solution of greater than about 200 cPs and less than about 2000 cPs, has a purity of greater than about 93%, and is present on the basesheet in an amount of less than about 4.5 gsm and greater than about 0.5 gsm.

21. An oil resistant article as defined in claim 1, wherein the oil resistant article has a Gurley permeability of greater than about 35,000 s / 100 mL.

22. An oil resistant article as defined in claim 1, wherein the oil resistant article has a Gurley permeability of less than about 45,200 s / 100 mL and greater than about 5,000 s / 100 mL.Attorney Docket No.: SMD-555-PCT (MATV-PAT-00555-PCT) 23. An oil resistant article as defined in claim 1, wherein the oil resistant article includes an oil resistant coating on the first side of the basesheet and an oil resistant coating on the second side of the basesheet.

24. An oil resistant article as defined in claim 1, wherein the basesheet does not contain filler particles.

25. An oil resistant article as defined in claim 1, wherein the oil resistant coating does not contain filler particles.

26. An oil resistant article as defined in claim 1, wherein the oil resistant article does not include any other coatings except for the oil resistant coating.

27. An oil resistant article as defined in claim 1, wherein the article displays a creased Kit oil rating of greater than 5.

28. An oil resistant article as defined in claim 1, wherein the oil resistant article is silicone free.

29. An oil resistant article as defined in claim 1, wherein the basesheet has a basis weight of from about 20 gsm to about 37 gsm.

30. An oil resistant article as defined in claim 1, wherein the oil resistant article has not been calendered.

31. A process for producing the oil resistant article as defined in claim 1 comprising: combining the pulp fibers with water and at least on other additive to form an aqueous suspension of fibers; depositing the aqueous suspension of fibers on a porous forming surface to form the basesheet; and applying an oil resistant composition to at least one side of the basesheet, the oil resistant composition containing the bio-based polymer; and drying the oil resistant composition to form the oil resistant coating.

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