Silicon release coating with grease and water barrier properties

Abstract

A coating composition contains the following components: (a) alkenyl-functional siloxane polymer with an average of at least two silicon-bonded alkenyl groups per molecule; (b) SiH-functional siloxane polymer containing an average of at least two SiH functionalities per molecule; (c) optionally, a non-reactive siloxane polymer; (d) hydrosilylation catalyst; (e) optionally, hydrosilylation reaction inhibitor; (f) surfactant; (g) an acid / base buffer that maintains a coating composition pH of less than 7; (h) alkyl and / or alkenyl succinic anhydride-modified starch; (i) water; (j) optionally, biocide; and (k) optionally, antifoam; where the molar ratio of SiH from component (b) to alkenyl groups from component (a) is in a range of 1.2 to 3.0.

Description

SILICON RELEASE COATING WITH GREASE AND WATER BARRIER PROPERTIESFIELDThe present invention relates to a silicone coating composition that can be used as a coating for substrates to impart grease, water, air barrier, abrasion resistance, and release properties.INTRODUCTIONBakery paper typically comprises a cellulosic substrate coated with a substance to promote release properties and water resistance. For instance, silicone emulsion coated cellulosic substrates are desirable bakery paper compositions. Other less desirable bakery paper compositions comprise cellulosic substrates coated with chrome complexes or fluoro-polymers. However, health concerns with heavy metal or fluorinated coatings make these latter options less desirable than silicone coated bakery paper compositions.There is a desire to increase the grease resistance of bakery paper. Silicone coated bakery papers are known for their release properties and water resistance. Silicones are known for water resistance, but not grease resistance. It is desirable to obtain a bakery paper that benefits from the healthier profile of silicones coated paper, but that has grease resistance in addition to water resistance and release properties.In particular, it is desirable to identify a composition that can coat a substrate to form a silicone coated bakery paper that has the following target performance characteristics: (a) low extractables as evidenced by an immediate value of less than 15%, preferably less than 14% and a post-cure value (24-hr value) of less than 10%, preferably less than 9% in the x-ray fluorescence (XRF) test described hereinbelow; (b) abrasion resistance evidenced by 90% or higher performance in the abrasion test described herein below; (c) water barrier as evidenced by less than 18 grams per square meter (g / nT) in a Cobb60 test described herein below; (d) grease barrier as evidenced by a value of 6 or higher in a 3M KIT test as described herein below; (e) release / low baking residues as evidenced by less than 11 g / nT residue in the bakery test described hereinbelow; and (f) air resistance as evidenced by a value of 10,000 seconds or higher in the Gurley test described hereinbelow.Moreover, it would further advance the art to be able to achieve these properties without using ethylene vinyl alcohol (EVOH) in the coating formulation. EVOH is a plastic additive that can be included in a composition to enhance gas barrier properties of the resulting coating.However, it is difficult to obtain a water-dispersible form of EVOH, especially one that is available at a price suitable for paper coatings.SUMMARYThe present invention provides a coating composition that can coat a substrate to form a silicone coated bakery paper that has the following target performance characteristics: (a) low extractables as evidenced by an immediate value of less than 15%, even less than 14% and a 24- hour value of less than 10%, even less than 9% in the x-ray fluorescence (XRF) test described hereinbelow; (b) abrasion resistance evidenced by 90%or higher performance in the abrasion test described herein below; (c) water barrier as evidenced by less than 18 grams per square meter (g / m ) in a Cobb60 test described herein below; (d) grease barrier as evidenced by a value of 6 or higher in a 3M KIT test as described herein below; (e) release / low baking residues as evidenced by less than 11 g / m residue in the bakery test described hereinbelow; and (f) air resistance as evidenced by a value of 10,000 seconds or higher in the Gurley Air Permeability Test described hereinbelow. Moreover, the present invention can achieve these properties without using ethylene vinyl alcohol (EVOH) in the coating composition.The present invention is a result of discovering that including an alkyl and / or alkenyl succinic anhydride-modified starch (such as octenyl succinate starch, or sodium octenyl succinate starch) into a silicone-based coating for bakery paper increases the grease resistance of the resulting coating while also achieving the other target performance characteristics and without the need for EVOH.In a first aspect, the present invention is a coating composition comprising the following components: (a) alkenyl-functional siloxane polymer with an average of at least two silicon- bonded alkenyl groups per molecule; (b) SiH-functional siloxane polymer containing an average of at least two SiH functionalities per molecule; (c) optionally, a non-reactive siloxane polymer; (d) hydrosilylation catalyst; (e) optionally, hydrosilylation reaction inhibitor; (f) surfactant; (g) an acid / base buffer that maintains a coating composition pH of less than 7 ; (h) alkyl and / or alkenyl succinic anhydride-modified starch; (i) water; (j) optionally, biocide; and (k) optionally, antifoam; where the molar ratio of SiH from component (b) to alkenyl groups from component (a) is in a range of 1.2 to 3.0.In a second aspect, the present invention is a process for making a non-stick coating, the process comprising combining the component of the coating composition of the first aspecttogether to form a mixture, coating a substrate with the mixture form a coating on the substrate, and then curing the coating.In a third aspect, the present invention is an article comprising a substrate coated with the coating composition of the first aspect, where the coating composition has undergone curing by a hydrosilylation reaction between the alkenyl-functional siloxane polymer and the SiH- functional siloxane polymer.The coating composition of the present invention is useful for preparing coating on food packaging materials as well as packaging for any materials that benefit from water and oil barrier properties. For example, the coating composition is useful for coating substrates to form articles suitable for use as bakery paper, French fry containers, hamburger packaging, pizza boxes, petfood bags, candle packaging, and soap packaging.DETAILED DESCRIPTIONTest methods refer to the most recent test method as of the priority date of this document when a date is not indicated with the test method number. References to test methods contain both a reference to the testing society and the test method number.Materials identified only by a product name or tradename refer to the material sold under that product name or tradename at the priority filing date of this document unless otherwise stated herein.“Multiple” means two or more. “And / or” means “and, or as an alternative”. All ranges include endpoints unless otherwise indicated. The sum of components in a composition do not exceed 100 weight-percent or volume-percent based respectively on the weight or volume of the composition.Determine viscosity for siloxane polymers according to ASTM method D4283-98.In a first aspect, the present invention is a coating composition. The coating composition is desirably aqueous continuous and can be an emulsion and / or dispersion. The coating composition comprises the following components: (a) alkenyl-functional siloxane polymer; (b) silylhydride (SiH)-functional siloxane polymer; (c) optionally, a non-reactive siloxane polymer; (d) hydrosilylation catalyst; (e) optionally, hydrosilylation reaction inhibitor; (f) surfactant; (g) an acid / base buffer that maintains a coating composition pH of less than 7 ; (h) alkyl and / or alkenyl succinic anhydride-modified starch; (i) water; (j) optionally, biocide; and (k) optionally, antifoam. The molar ratio of SiH from the SiH-functional siloxane polymer to alkenyl groups from the alkenyl-functional siloxane polymer is in a range of 1.2-3.0. The coating compositioncan be free of ethylene vinyl alcohol (EVOH). The coating composition can be free of any organic copolymer comprising at least two types of repeating units: (i) an alkyl group comprising 2 to 12 carbon atoms; and (ii) an alkyl group with 2 to 12 carbon atoms and at least one pendant alcohol. The coating composition can be free of ethylene- vinyl ester copolymers.(a) Alkenyl-functional siloxane polymerThe alkenyl-functional siloxane polymer preferably has at least two silicon-bonded alkenyl-functional groups per molecule. The alkenyl group is preferably linear having up to 6 carbon atoms, as exemplified by hexenyl, vinyl, allyl or pentenyl, or may be cycloalkenyl such as cyclohexenyl. Vinyl groups may be desirable for cost and regulations reasons, especially for food related uses.The organopolysiloxane containing alkenyl groups can contain terminal and / or pendant alkenyl groups. If the organopolysiloxane has terminal alkenyl groups it is an alkenyl-terminated polydiorganosiloxane. The alkenyl-functional siloxane polymer can for example be a linear organopolysiloxane having the general formula:¥X2SiO(X2SiO)x(XYSiO)ySiX2Y wherein each X denotes independently a phenyl group or an alkyl or cycloalkyl group having from 1 to 10 carbon atoms, for example, methyl, ethyl, propyl, butyl or cyclohexyl; each Y denotes an alkenyl group; subscript x typically has a value of zero or more, preferably 20 or more, 40 or more, 60 or more, 80 or more, 100 or more, even 120 or more while at the same time is typically 500 or less, and can be 250 or less, 200 or less, 150 or less, 140 or less, 130 or less, even 120 or less; subscript y typically has a value of zero or more, preferably 20 or more, 40 or more, 60 or more, 80 or more, 100 or more, even 120 or more while at the same time is typically 500 or less, and can be 250 or less, 200 or less, 150 or less, 140 or less, 130 or less, even 120 or less; and desirably x and y are such that the organopolysiloxane has a viscosity at 25° C in a range from 5 to 10,000 square millimeters per second (mm2 / s), more preferably 50 to 500 mm Is. The organopolysiloxane containing alkenyl groups can be a linear vinyl end-capped siloxane polymer such as a dimethylvinylsiloxy-terminated polydiorganosiloxane, or a hexenyl terminated polydiorganosiloxane, such as a dimethyl (5-hexenyl)siloxy-terminated polydiorganosiloxane. Preferably, at least 50% of all the X substituents of the alkenyl-functional siloxane polymer are methyl groups, most preferably all being methyl groups. It is possible but not preferred that small amounts (preferably less than 10% of all the substituents present) of other substituents are present, for example hydroxyl groups. Alternatively, theorganopolysiloxane containing alkenyl groups is free of substituents extending from the polysiloxane backbone other than hydrocarbyl groups. An example of a suitable linear organopolysiloxane containing alkenyl groups is a linear vinyl end-capped polydimethylsiloxane having an average of 120 dimethylsiloxane units, which is commercially available from Gelest under the name DMS-V22.The alkenyl-functional siloxane polymer can be a branched siloxane comprising one or more Q units of the formula (SiC>4 / 2), from 15 to 995 D units of the formula Rb2SiO2 / 2 and M units of the formula RaRb2SiOi / 2. wherein the Raand Rbsubstituents are selected from alkyl groups having 1 to 6 carbon atoms and alkenyl groups having 2 to 6 carbon atoms. Preferably the Rbsubstituents are alkyl groups, most preferably methyl groups. At least two, and preferably at least three, Rasubstituents in such a Q-branched siloxane are alkenyl groups, as described in EP- A- 1070734. Vinyl groups can be present as methylvinylsiloxane units. Such a siloxane may for example be a poly(dimethylsiloxane-silicate) copolymer having at least three vinyldimethylsilyl-terminated siloxane branches. The branched siloxane can also incorporate other terminal groups such as terminal trimethylsilyl (SiMe3) and / or terminal hydroxy dimethylsilyl (SiMe2OH) groups. The Q branched siloxane can contain other additional branching groups, for example it can also incorporate units. Branched siloxanes have the advantage that they allow faster cure than linear polymers with similar viscosities.The alkenyl-functional siloxane polymer is typically present at a concentration of 2 wt% or more, 4 wt% or more, 6 wt% or more, 8 wt% or more, 9 wt% or more, even 10 wt% or more while at the same time is typically 20 wt% or less, 18 wt% or less, 16 wt% or less, 14 wt% or less, 12 wt% or less, 10 wt% or less, or even 9.5 wt% or less with wt% values based on coating composition weight.(b) SiH-functional siloxane polymerThe silylhydride (SiH)-functional siloxane polymer generally contains an average of at least 2 or 3 SiH groups per molecule. The SiH-functional siloxane polymer can have the general formula:Rt3SiOl / 2((CH3)2SiO2 / 2)d(Rt2SiO2 / 2)e)SiOl / 2 R where each Rlcan be an alkyl group having 1 to 4 carbon atoms or hydrogen, d and e are 0 or any number such that d+e is from 8 to 400. Preferably the SiH-functional siloxane polymer comprises at least two or three methylhydrogensiloxane units. The SiH-functional siloxane polymer can for example be a poly(methylhydrogensiloxane) having trimethylsilyl terminal unitsor a dimethylsiloxane methylhydrogensiloxane copolymer having trimethylsilyl terminal units. The crosslinking agent can alternatively contain SiH groups in a linked cyclic polyorganosiloxane structure. Such linked cyclic polyorganosiloxanes can be produced by reacting a cyclic polysiloxane containing at least two SiH groups with a compound having aliphatic unsaturation or containing a hydroxy group, for example a silane or polyorganosiloxane having aliphatic unsaturation or containing a hydroxy group as described in US7378482.The SiH-functional siloxane polymer can be an MQ resin consisting of units of the general formula SiC>4 / 2 and Rq3SiOi / 2 wherein at least three Rqsubstituents in the MQ resin molecule are hydrogen atoms and the remainder are alkyl groups, or may be a rake or comb polymer comprising a polydiorganosiloxane chain containing one or more T or Q unit having a subchain of diorganosiloxane and organohydrogensiloxane units attached thereto. Preferably, the SiH-functional siloxane polymer has a viscosity of from 5 to 1000 mm2 / s at 25° C, more preferably 20 to 350 mm / s, most preferably 50 to 300 mnr / s. The SiH-functional siloxane polymer is preferably present in an amount such that the molar ratio of the total number of H groups in the coating composition to alkenyl groups in the coating composition is from 0.9: 1 to 8:1, preferably 1.1:1 to 4:1, more preferably 1.2: 1 to 3.0: 1, and most preferably 1.5:1 to 3: 1.The SiH-functional siloxane polymer is typically present at a concentration of 0. 1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, 0.6 wt% or more, 0.7 wt% or more, 0.8 wt% or more, 0.9 wt% or more, even 1.0 wt% or more while at the same time is typically 4.0 wt% or less, 3.0 wt% or less, 2.0 wt% or less, 1.0 wt% or less, 0.8 wt% or less, 0.6 wt% or less, or even 0.5 wt% or less, with wt% values based on coating composition weight.(c) Non-reactive siloxane polymerThe non-reactive siloxane polymer is an optional component. It can be desirable to include the non-reactive siloxane polymer to, for example, serve as a surface lubricating agent useful in industrial processes where friction and shear apply. It can also be desirable to minimize or avoid use of non-reactive siloxane polymers because they can be extractable components from resulting cured coating, which can be undesirable particularly in food applications. The non-reactive siloxane polymer is free of reactive groups such as SiH groups, alkenyl groups, and hydroxyl groups. Typically, the non-reactive siloxane polymer has only hydrocarbyl groups bound the silicon atoms of the siloxane polymer.Typical non-reactive siloxane polymer for use in the present invention are linear trimethyl end-blocked polydimethylsiloxanes. The non-reactive siloxane polymer can have the following average structure:[(CH3)3SiO][(CH3)2SiO]w[(CH2)3Si] where subscript w is typically 5 or more, and can be 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, 75 or more, 100, or more, 150 or more, even 200 or more and at the same time is typically 10,000 or less, and can be 9000 or less, 8000 or less, 7000 or less, 6000 or less, 5000 or less, 4000 or less, 3000 or less, 2000 or less, 1000 or less, 900 or less, 800 or less, 700 or less, 600 or less, even 500 or less. DOWSIL™ 200 fluid products are examples of suitable linear trimethyl end-blocked poly dimethylsiloxanes. One example of a suitable linear trimethyl end- blocked polydimethylsiloxane has an average viscosity of 12,500 mm2 / s and is available under the name DOWSIL™ 200 Fluid 12,500 cSt from The Dow Chemical Company (DOWSIL is a trademark of The Dow Chemical Company).The concentration of non-reactive siloxane polymer in the coating composition is typically zero wt% or more and can be 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, even 0.5 wt% or more, while at the same time is typically 5 wt% or less, and can be 4 wt% or less, 3 wt% or less, 2 wt% or less, one wt% or less, 0.8 wt% or less, 0.6 wt% or less, or even 0.5 wt% or less, with wt% values based on coating composition weight.(d) Hydrosilylation catalystThe hydrosilylation catalyst preferably comprises a platinum group metal that is a group VIII metal such as platinum, ruthenium, rhodium, palladium, osmium or indium. Suitable hydrosilylation catalysts include complexes or compounds of these platinum group metals, particularly platinum compounds or complexes including chloroplatinic acid, either in hexahydrate form or anhydrous form, and or a platinum-containing catalyst which is obtained by a method comprising reacting chloroplatinic acid with an aliphatically unsaturated organosilicon compound such as divinyltetramethyldisiloxane, platinum acetylacetonate, complexes of platinous halides with unsaturated compounds, for example, ethylene, propylene, organovinylsiloxanes and styrene, hexamethyldiplatinum, alkene-platinum-silyl complexes such as (COD)Pt(SiMeC12)2, where COD is 1,5-cyclooctadiene and Me is methyl, PtC12.PtCl3and Pt(CN)3. Alternatively, the catalyst may be a rhodium complex, for example, RhC13(Bu2S)3.Platinum-based hydrosilylation catalysts include compounds and complexes such as platinum (0)-l,3-divinyl-l,l,3,3-tetramethyldisiloxane (Karstedt’s catalyst), I LPtCL,, di-p.-carbonyl di-.7i.-cyclopentadienyldinickel, platinum-carbonyl complexes, platinum- divinyltetramethyldisiloxane complexes, platinum cyclovinylmethylsiloxane complexes, platinum acetylacetonate (acac), platinum black, platinum compounds such as chloroplatinic acid, chloroplatinic acid hexahydrate, a reaction product of chloroplatinic acid and a monohydric alcohol, platinum bis(ethylacetoacetate), platinum bis(acetylacetonate), platinum dichloride, and complexes of the platinum compounds with olefins or low molecular weight organopolysiloxanes or platinum compounds microencapsulated in a matrix or core-shell type structure. The hydrosilylation catalyst can be part of a solution that includes complexes of platinum with low molecular weight organopolysiloxanes that include 1,3-diethenyl-l, 1,3,3- tetramethyldisiloxane complexes with platinum. These complexes may be microencapsulated in a resin matrix. The catalyst can be 1,3-diethenyl- 1,1,3, 3 -tetramethyldisiloxane complex with platinum.The concentration of hydrosilylation catalyst is desirably sufficient to increase the reaction rate of a hydrosilylation reaction between the alkenyl-functional siloxane polymer and the SiH-functional siloxane polymer. The concentration of actual catalyst compound will vary depending on what catalyst compound is in the coating composition. For the particular Karstedt’s catalyst composition used in the examples of the present invention, the concentration of the catalyst composition is typically 0.01 wt% or more, 0.02 wt% or more, 0.03 wt% or more, 0.04 wt% or more, 0.05 wt% or more, 0.06 wt% or more, 0.07 wt% or more, 0.08 wt% or more, 0.09 wt% or more, even 0.10 wt% or more, while at the same time is typically 0.50 wt% or less, 0.40 wt% or less, 0.30 wt% or less, 0.20 wt% or less, or even 0.10 wt% or less, with wt% values based on coating composition weight.(e) Hydrosilylation reaction inhibitorHydrosilylation inhibitor can be used for altering when and / or how fast the hydrosilylation reaction occurs. Hydrosilylation inhibitor can be, for example, one or more than one material selected from a group consisting of an acetylenic alcohol, an acetylenic alcohol, an ene-yne compound, a triazole, a phosphine, a mercaptan, a hydrazine, an amine, a fumarate, a maleate, an ether, carbon monoxide, an alkenyl -functional siloxane oligomer, and a combination of two or more thereof.Acetylenic alcohols are exemplified by 3,5-dimethyl-l-hexyn-3-ol, l-butyn-3-ol, 1- propyn-3-ol, 2-methyl-3-butyn-2-ol, 3-methyl-l-butyn-3-ol, 3 -methyl- l-pentyn-3-ol, 3-phenyl- l-butyn-3-ol, 4-ethyl-l-octyn-3-ol, 3,5-dimethyl-l-hexyn-3-ol, and 1-ethynyl-l -cyclohexanol, and a combination thereof. The acetylenic alcohol can be a silylated acetylenic compound.Without wishing to be bound by theory, it is thought that adding a silylated acetylenic compound reduces yellowing of the reaction product prepared from hydrosilylation reaction as compared to a reaction product from hydrosilylation of starting materials that do not include a silylated acetylenic compound or that include an organic acetylenic alcohol inhibitor, such as those described above. Silylated acetylenic compounds are exemplified by (3 -methyl- l-butyn-3- oxy)trimethylsilane, ((1 ,l-dimethyl-2-propynyl)oxy)trimethylsilane, bis(3-methyl-l-butyn-3- oxy)dimethylsilane, bis(3-methyl-l-butyn-3-oxy)silanemethylvinylsilane, bis((l,l-dimethyl-2- propynyl)oxy)dimethylsilane, methyl(tris(l,l-dimethyl-2-propynyloxy))silane, methyl(tris(3- methyl-l-butyn-3-oxy))silane, (3-methyl-l-butyn-3-oxy)dimethylphenylsilane, (3-methyl-l- butyn-3-oxy)dimethylhexenylsilane, (3-methyl-l-butyn-3-oxy)tri ethylsilane, bis(3-methyl-l- butyn-3-oxy)methyltrifluoropropylsilane, (3,5-dimethyl-l-hexyn-3-oxy)trimethylsilane, (3- phenyl-l-butyn-3-oxy)diphenylmethylsilane, (3-phenyl-l-butyn-3-oxy)dimethylphenylsilane, (3 -phenyl- l-butyn-3 -oxy )dimethylvinylsilane, (3-phenyl-l-butyn-3-oxy)dimethylhexenylsilane, (cyclohexyl- 1 -ethy n- 1 -oxy )dimethylhexenylsilane, (cyclohexyl- 1 -ethyn- 1 - oxy)dimethylvinylsilane, (cyclohexyl- 1 -ethyn- 1 -oxy)diphenylmethylsilane, (cyclohexyl- 1 - ethyn- l-oxy)trimethylsilane, and combinations thereof. The silylated acetylenic compound useful as the inhibitor herein may be prepared by methods known in the art, for example, U.S. Patent 6,677,407 to Bilgrien, et al. discloses silylating an acetylenic alcohol described above by reacting it with a chlorosilane in the presence of an acid receptor.Ene-yne compound include 3-methyl-3-penten-l-yne; 3,5-dimethyl-3-hexen-l-yne; and a combinations thereof. Triazole include benzotriazole.Amines are exemplified by tetramethyl ethylenediamine, 3-dimethylamino-l-propyne, n- methylpropargylamine, propargylamine, 1-ethynylcyclohexylamine, or a combination thereof.Fumarates include dialkyl fumarates such as diethyl fumarate, dialkenyl fumarates such as diallyl fumarate, dialkoxyalkyl fumarates such as bis-(methoxymethyl)ethyl fumarate.Maleates include dialkyl maleates such as diethyl maleate, dialkenyl maleates such as diallyl maleate, and dialkoxyalkyl maleates such as bis-(methoxymethyl)ethyl maleate.The inhibitor may comprise an alkenyl-functional siloxane oligomer, which may be cyclic or linear such as methylvinylcyclosiloxanes exemplified by 1,3, 5, 7-tetramethyl-l, 3, 5, 7- tetravinylcyclotetrasiloxane, 1,3, 5, 7-tetramethyl-l, 3, 5, 7-tetrahexenylcyclotetrasiloxane, 1,3- divinyl-l,3-diphenyl-l,3-dimethyldisiloxane; l,3-divinyl-l,l,3,3-tetramethyldisiloxane; and a combination of two or more thereof.The concentration of hydrosilylation reaction inhibitor in the coating composition is typically zero wt% or more, 0.01 wt% or more, 0.02 wt% or more, 0.03 wt% or more, even 0.04 wt% or more, while at the same time is typically 0.08 wt% or less, 0.07 wt% or less, 0.06 wt% or less, 0.05 wt% or less, or even 0.04 wt% or less, with wt% values based on coating composition weight.(f) SurfactantSurfactants are useful for stabilizing the components of the present invention as an emulsion and / or dispersion in a water-continuous phase.The surfactant can be nonionic and / or ionic. Preferably, the surfactant is nonionic. Suitable surfactants can be selected from those that are known and the art and are commercially available. Suitable nonionic surfactants include alkylphenols, fatty alcohols or fatty acids with alkylene oxide groups, such as ethylene oxide or propylene oxide groups. Suitable ionic surfactants include anionic surfactants such as sulfates, sulfonates, phosphates, and sulfosuccinates. Suitable surfactants for use herein are exemplified by those described as surfactant (G) in U.S. Patent Application Publication 2007 / 0099007 at paragraphs

[0167] to

[0176] .It can be desirable to use a combination of surfactants. For instance, polyvinyl alcohol (PVA) can be a primary surfactant and a poly(oxy- 1 ,2-ethanediyl) can be a co-surfactant.Examples of surfactants for use in the present invention include those available under the names PVA 40 TAD from BIM Kemi AB and LUTENSOL ™ XP100 (LUTENSOL is a trademark of BASF SE).The concentration of surfactants in the coating composition is typically greater than zero, preferably 0.5 wt% or more, 1.0 wt% or more, 2.0 wt% or more, 3.0 wt% or more, 3.5 wt% or more, 4.0 wt% or more, 5.0 wt% or more, 6.0 wt% or more, even 7.0 wt% or more, while at the same time is typically 10.0 wt% or less, 9.0 wt% or less, 8.0 wt% or less, 7.0 wt% or less, 6.0 wt% or less, 5.0 wt% or less, even 4.0 wt% or less, with wt% values based on coating composition weight.(g) Acid / Base BufferThe coating composition of the present invention includes an acid / base buffer, which is a combination of acid and a base compounds that serves as a buffer to maintain the coating composition at a pH of less than 7.In the broadest scope of the invention, the acid / base buffer (buffer) can be any acid / base buffer. The acid / base buffer typically comprises a mono or polyprotic acid and its conjugatebase. For example, one example of a suitable buffer comprises HCOf / COs2’ and H2PO4 / HPO42’ as described as agent F in U.S. Patent Application Publication 2007 / 0099007 at paragraphs

[0145] to

[0147] may be used herein. The buffer can comprise NaCOr and NaHCCh. The buffer can comprise citric acid and a citrate salt such as potassium citrate or sodium citrate. The acid / base buffer can be formed by combining a polyprotic acid (such as citric acid) with a base (such as sodium hydroxide) at a molar ratio such that fewer than all of the polyprotic acid is neutralized. One of ordinary skill can choose appropriate relative concentrations of selected acids and bases as well as the required amount of total buffer necessary to achieve a buffer that maintains a pH of less than 7 for a given coating composition. Desirably, the buffer maintains the coating composition at a pH of 7 or less, but it can maintain it at a pH of 6 or less, while at the same time the buffer desirably maintains the coating composition at a pH of one or more, 2 or more, even 3 or more, or 4 or more.The amount of the acid / base buffer (combination of acid and its conjugate base) is typically greater than 0 wt%, alternatively 0.02 wt% or more, 0.03 wt% or more, 0.04 wt% or more, 0.05 wt% or more, 0.06 wt% or more, 0.07 wt% or more, 0.08 wt% or more, 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, even 0.5 wt% or more, and at the same time is typically 2.0 wt% or less, 1.8 wt% or less, 1.6 wt% or less, 1.4 wt% or less, 1.2 wt% or less, 1.0 wt% or less, 0.8 wt% or less, 0.6 wt% or less, 0.5 wt% or less, 0.4 wt% or less, 0.3 wt% or less, 0.2 wt% or less, 0.1 wt% or less, 0.08 wt% or less, or even 0.06 wt% or less based on coating composition weight.Alkyl and / or alkenyl succinic anhydride-modified starchThe alkyl and / or alkenyl succinic anhydride-modified starch is a starch compound that has been modified with an alkyl and / or alkenyl succinic anhydride compound. “Modified” means that the starch compound has undergone esterification reactions with alkyl and / or alkenyl succinic anhydride compounds. In the broadest scope of the invention, the extent of esterification (or “modification”) of the starch is presumably not critical as long as it is modified. It is possible to characterize the extent of modification by designating a degree of substitution using a nuclear magnetic resonance (NMR) method such as that taught in the article: M.C. Sweedman et al., Carbohydrate Polymers 92 (2013) 905-920 at section 3.2.2. The degree of substitution (DS) for the alkyl and / or alkenyl succinic anhydride-modified starch of the present invention is desirably greater than zero, preferably 0.01 or more, more preferably 0. 1 or more, 0.12 or more, even 0.18 or more, while at the same time can be 2.5 or less, 2 or less, one or less, 0.80 or less, 0.60 or less, 0.40 or less, 0.20 or less, even 0.18 or less. DS refers to the averagenumber of alkyl and / or alkenyl succinic anhydride groups per glucose unit in the alkyl and / or alkenyl succinic anhydride modified starch material.In the broadest scope of the present invention, the type of starch is not critical.Desirably, the starch comprises 50% or more, 60% or more, 80% or more, 90% or more, even 95% or more amylopectin content. Amylopectin content can be classically determined by one of ordinary skill in the art by way of potentiometric analysis of iodine absorbed by amylose to form a complex. Desirably, the starch is maize starch. The starch can be a waxy starch, such as waxy maize starch. In the broadest scope of the present invention, the alkyl and / or alkenyl succinic anhydride is one or more than one compound having the following chemical structure:where there can be one Rsor two groups bound to carbons of the succinic anhydride that are not directly bound to oxygen, and each Rsis independently selected from alkyl and alkenyl groups. Typically, the alkyl and / or alkenyl succinic anhydride compound contain one such Rsgroup per molecule. The alkyl and alkenyl groups are selected from those having 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, even 19 or more carbon atoms while at the same time typically containing 20 or fewer, 19 of fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, 6 or fewer, 5 or fewer, even 4 or fewer carbon atoms. Examples of suitable Rsgroups include allyl, octenyl groups, octyl groups, dodecyl groups, dodecenyl groups, hexadecenyl groups, and 2-methyl-2-propenyl groups. The alkyl and / or alkenyl succinic anhydride is desirably octenyl succinic anhydride (OSA).The most preferred alkyl and / or alkenyl succinic anhydride compound is OSA-modified starch, preferably OSA-modified maize starch, more preferably OSA-modified waxy maize starch, even more preferably what is called an acid and sodium OSA treated waxy maize starch. One desirable acid and sodium OSA treated waxy maize starch is commercially available under the name STABILYS™ BA25 from Roquette, which has a DS of 0.022 corresponding to having an average of 0.022 OSA units bound to the OSA-modified maize starch per glucose unit in the OSA-modified maize starch. Other suitable acid and sodium OSA treated waxy maize starchmaterials are similar but have a DS of 0. 12 and 0.18 and can be prepared as described in the Example section, below.The concentration of the alkyl and / or alkenyl succinic anhydride modified starch in the coating composition is typically one wt% or more, and can be 2 wt% or more, 3 wt% or more, 4 wt% or more, 5 wt% or more, 6 wt% or more, 7 wt% or more, 8 wt% or more, 9 wt% or more, 10 wt% or more, 1 1 wt% or more, 12 wt% or more, 1 wt% or more, 14 wt% or more, even 15 wt% or more, while at the same time is typically 25 wt% or less, 20 wt% or less, 18 wt% or less, 16 wt% or less, 14 wt% or less, even 12 wt% or less, with wt% values based on coating composition weight.(h) WaterWater serves as a continuous phase in the coating composition of the present invention. The water is not generally limited, and may be utilized neat (that is, absent any carrier vehicles / solvents), and / or pure (that is, free from or substantially free from minerals and / or other impurities). For example, the water may be processed or unprocessed before use in the process described above. Examples of processes that may be used for purifying the water include distilling, filtering, deionizing, and combinations of two or more thereof, such that the water may be deionized, distilled, and / or filtered. Alternatively, the water may be unprocessed (e.g. may be tap water provided by a municipal water system or well water, used without further purification). Alternatively, the water may be purified before use in the process.The concentration of water in the coating composition (including the water used to carry other components into the coating composition as solutions) is typically 20 wt% or more, 30 wt% or more, 40 wt% or more, and can be 50 wt% or more, 60 wt% or more, 70 wt% or more, even 80 wt% or more, while at the same time is typically 95 wt% or less, 90 wt% or less, 85 wt% or less, 82 wt% or less, 80 wt% or less, even 75 wt% or less, with wt% values based on coating composition weight.(i) BiocideBiocide is desirable in the present coating composition to inhibit growth of undesirable organisms in the coating composition. It is particularly desirable considering the presence of the alkyl and / or alkenyl succinic anhydride-modified starch component. The coating composition can contain multiple biocides as the biocide component.Suitable biocides include any biocides known in the art. For example, the biocide can be a fungicide, an herbicide, a pesticide, an antimicrobial agent, or a combination of two or more thereof. Exemplary biocides are disclosed, for example, in U.S. Patent 9,221,041.Specific examples of suitable biocides for use in the present invention include those available under the names KATHON™ LXE (KATHON is a trademark of Nutrition & Biosciences USA2, LLC) and BIOBAN™ 1530 (BIOBAN is a trademark of Lanxess Corporation).The concentration of biocide in the coating composition is typically zero wt% or more and can be 0.005 wt% or more, 0.01 wt% or more, 0.02 wt% or more, 0.03 wt% or more, 0.04 wt% or more, 0.05 wt% or more, while at the same time is typically 0.30 wt% or less, 0.20 wt% or less, 0.10 wt% or less, 0.08 wt% or less, 0.06 wt% or less, or even 0.04 wt% or less, with wt% values based on coating composition weight.(j) AntifoamAntifoam components can be desirable in the present coating composition to prevent undesirable frothing of the coating composition during formulating and use.Examples of suitable anti-foaming components include emulsions containing silica and polydimethylsiloxanes. Suitably commercially available anti-foaming components include those available under the tradenames DOWSIL™ 7989, SYL-OFF™ EM 25 7989 ANTIFOAM, XIAMETER™ AFE-0100, XIAMETER™ AFE-1510, XIAMETER™ AFE-1520, and XIAMETER™ AFE-1530. DOWSIL is a trademark of The Dow Chemical Company. XIAMETER and SYL-OFF are trademarks of Dow Silicones Corporation.The concentration of antifoam in the coating composition is typically zero wt% or more, and can be 0.01 wt% or more, 0.02 wt% or more, 0.03 wt% or more, 0.04 wt% or more, 0.05 wt% or more, 0.06 wt% or more, even 0.07 wt% or more, while at the same time is typically 0.20 wt% or less, and can be 0.10 wt% or less, 0.08 wt% or less, 0.06 wt% or less, even 0.05 wt% or less, with wt% values based on coating composition weight.The coating composition of the present invention desirably comprises: (a) a water at a concentration in a range of 20 to 95 weight-percent (wt%); (b) a concentration of siloxane polymer components (components (a), (b) and (c)) that is in a range of 2 to 20 wt%, and that is preferably 2 wt% or more, 4 wt% or more, 8 wt% or more, even 9 wt% or more, while at the same time is 20 wt% or less, 18 wt% or less, 16 wt% or less, 14 wt% or less, 12 wt% or less, or even 10 wt% or less; and (c) a concentration of alkyl and / or alkenyl succinic anhydride-modified starch that is in a range of 0.45 to 18 wt%, and that is preferably 0.45 wt% or more, 0.50 wt% or more, 1.0 wt% or more, 2.0 wt% or more, 4.0 wt% or more, 6.0 wt% or more, 8.0 wt% or more,10 wt% or more, even 12 wt% or more, while at the same time is 18 wt% or less, 16 wt% or less, 14 wt% or less, or even 12 wt% or less; with wt% values relative to coating composition weight.The coating composition of the present invention can consist of a single mixture of all of the components together as a single emulsion or dispersion. Alternatively, the coating composition can comprise multiple mixtures each containing a selection of the components. Multiple mixtures can be desirable to, for instance, separate the catalyst from reactants so that the coating composition remains stable until such time as it is ready to be used when the mixtures can be combined into a single mixture.In one desirable form of the coating composition the composition comprises at least two separate parts that remain distinct from one another until blended to form a single coating composition. One of the two parts (a “first” part, or “base emulsion”) comprises: (i) water; (ii) surfactant; (iii) alkenyl-functional siloxane polymer; (iv) SiH-functional siloxane polymer; and (v) optionally, non-reactive siloxane polymer. Another of the two parts (a “second” part) comprises: (i) water; (ii) surfactant; and at least one component selected from (iii) alkenyl- functional siloxane polymer; (iv) SiH-functional siloxane polymer; and (v) non-reactive siloxane polymer. The anhydride-modified starch can be a separate part, or can be included in one of the other parts. The hydrosilylation catalyst is either maintained as a separate third part or combined into the second part as long as the second part does not contain both alkenyl-functional siloxane polymer and SiH-functional siloxane polymer. If the hydrosilylation catalyst is included in the second part, it is desirable for the second part to also contain the hydrosilylation reaction inhibitor. The remaining components can be in either one or both of the first or second part, or can be one or more additional separate part. The antifoam component when present can desirably be an antifoam emulsion and can be its own part or combined with one of the other parts.In a second aspect, the present invention is a process for making a non-stick coating, the process comprises combining the component of the coating composition of the first aspect of the present invention together to form a mixture, coating a substrate with the mixture to form a coating on the substrate, and then curing the coating. Typically, the process also includes drying the coating after it is on the substrate and before, during or after curing it. Curing involves hydrosilylation reaction between the alkenyl-functional siloxane polymer and the SiH-functional siloxane polymer. Typically, curing and drying occur at the same time by exposing the coating on the substrate to a temperature in a range of 110 to 180 degrees Celsius (°C). The process cancomprise providing the coating composition of the first aspect as multiple parts and then combining them together to form the mixture used to coat a substrate.In a third aspect, the present invention is an article comprising a substrate coated with the coating composition of the first aspect , where the coating composition has undergone curing by hydrosilylation between the alkenyl- functional siloxane polymer and the SiH-functional polymer. The article can be made according to the process of the second aspect.EXAMPLESTable 1 identifies the components for use in making the samples that follow. “Me” refers to a methyl group. “Vi” refers to a vinyl group.Table 1.SYL-OFF is a trademark of Dow Silicones Corporation. DOWSIL is a trademark of The Dow Chemical Company. XIAMETER is a trademark of Dow Corning Corporation. SURFYNOL is a trademark of Evonik Operation s GMBH. LUTENSOL is a trademark of BASF SE. KATHON is a trademark of Nutrition & Biosciences USA 2, LLC. BIOBAN is a trademark of Lanxess Corporation. STABILYS is a trademark of Roquette.Synthesis of Modified Starch H2Combine 185.59 grams (g) of Modified Starch H with 348.4 g of deionized water in a flask having a pH of 5.7. Heat the contents of the flask to 65 °C for 69 minutes while adding 5.2 milliliters (mL) of sodium hydroxide solution to reach a pH in a range of 9.0 to 10.0. Add 56.0 g of OSA to the solution over a 5 hour period while maintaining a pH in a range of 8.5 to 9.0 after each addition of OSA. Cool the resulting mixture to 25 °C and neutralize with 1 Normal hydrochloric acid solution to obtain a pH in a range of 6.5 to 7.0. Add 603 g of acetone and shake for 10 minutes. Filter the resulting product slurry using a Buchner funnel and wash three times with ethanol to remove unreacted OSA. Dry the solid component at 110 °C in an oven for 12 hours resulting in 167 g of dry product. NMR analysis confirms the product is OSA- modified starch with a degree of substitution of 0.12.Synthesis of Modified Starch H3Combine 162.4 grams (g) of Modified Starch H with 304.4 g of deionized water in a flask having a pH of 5.3. Heat the contents of the flask to 65 °C for 40 minutes while adding 4.5 mL of sodium hydroxide solution to reach a pH in a range of 8.5 to 9.5. Add 56.0 g of OSA to the solution over a 5 hour period while maintaining a pH in a range of 8.5 to 9.0 after each addition of OSA. Cool the resulting mixture to 25 °C and neutralize with 1 Normal hydrochloricacid solution to obtain a pH in a range of 6.5 to 7.0. Add 603 g of acetone and shake for 10 minutes. Filter the resulting product slurry using a Buchner funnel and wash three times with ethanol to remove unreacted OSA. Dry the solid component at 110 °C in an oven for 12 hours resulting in 158 g of dry product. NMR analysis confirms the product is OSA-modified starch with a degree of substitution of 0. 18.Preparation of Base Emulsion (First Part)Table 2 provides the composition of the Base Emulsion, with amounts for the components listed in wt% relative to the Base Emulsion weight.Table 2.Prepare an aqueous acid / base buffer solution by blending the water, Buffer Acid G, and Base G components together. Weigh out separately the Vinyl Siloxane A, SiH Siloxane B, and Non-reactive siloxane C and then mix them together to form a polymer mix. Weigh out separately the surfactants and mix them together to form a polymer mix. Slowly add the surfactant mix to the polymer mix while emulsifying using a high pressure sonolator at 100 bars until obtaining a Dv0.9 particle size between 1.0 and 2.5 micrometers, preferably between 1.5 and 2.0 micrometers. Determine DV0.9 particle size using laser diffraction spectroscopy with a Malvern Mastersizer 3000 instrument. To the emulsion add the buffer solution, inhibitors and biocides while continuing to emulsify. The resulting emulsion is the Base Emulsion.Preparation of Catalyst Emulsion (Second Part)Table 3 provides the composition of the Catalyst Emulsion, with amounts for the components listed in wt% relative to the Catalyst Emulsion weight.Table 3.Prepare an aqueous acid / base buffer solution by blending the water, Buffer Acid G, and Base G components together. Weigh out separately the Vinyl Siloxane A and Catalyst D, and then mix them together to form a polymer mix. Weigh out separately the surfactants and mix them together to form a polymer mix. Slowly add the surfactant mix to the polymer mix while emulsifying using a high pressure sonolator at 100 bars until obtaining a Dv0.9 particle size between 1.0 and 2.5 micrometers, preferably between 1.5 and 2.0 micrometers. Determine DV0.9 particle size using laser diffraction spectroscopy with a Malvern Mastersizer 3000 instrument. To the emulsion add the buffer solution and biocides while continuing to emulsify. The resulting emulsion is the Catalyst Emulsion.Preparation of Starch SolutionsPrepare four different starch solutions. For each of the starch solutions, first determine the solids content for the starch component for use in the starch solution to account for any water that is present. Then dilute the starch component down with water to obtain the final starch solution. The four starch solutions are:(1) Modified Starch Solution A, which contains 20 wt% Modified Starch H.(2) Modified Starch Solution B, which contains 5 wt% Modified Starch H2(3) Modified Starch Solution C, which contains 5 wt% Modified Starch H3; and(4) Maize Starch Solution, which contains 22.8 wt% Maize Starch.Determine solids content for the starch components using a CEM Smart Turbo System 5 microwave dryer and moisture analyzer. Combine each starch component with enough additional water to achieve the target solids content (see below) and then heat the resulting combination to 80 °C for several hours until the starch component completely dissolves in thewater. Cool the resulting solution to 25 °C and confirm the solids content using a CEM Smart Turbo System 5 microwave dryer and moisture analyzer.To only the resulting starch solution (1) “Modified Starch Solution A”, add a blend of Biocide J(l) and Biocide J(2) to obtain a Starch Solution that has 0.08 weight parts Biocide J(l) and 0.05 weight-parts of Biocide J(2) per 100 weight-parts of Starch Solution.Sample Coating Compositions and Coating SubstratesPrepare Examples (Ex) 1-8 and Comparative Examples (CE) 1-13 by combining components at the weight percent values listed in Table 4. Mix the components well and just prior to coating them onto a substrate of bakery paper (from Metsa). Immediately after preparing the sample coating compositions, coat them onto bakery paper using a bench top rotary printing and coating machine called “The Rotary Koater” from RK Print-Coat Instrument Ltd. the paper speed is set at 7 meters / minute. The coated paper immediately is cured and dried by running the coated paper through an in-line oven set a 150 °C. The resulting coated, cured and dried paper samples are cut into sheets for further characterization described below.Table 4Characterization of Coated Substrates after Curing and DryingCharacterize each sample of coated, dried and cured sample using the following characterization methods. Also, as a reference, characterize a sample of uncoated bakery paper substrate. Characterization results are in Table 5 and Table 6. Table 5 and Tabel 6 also list the components of each coating composition sample in terms of wt% of each component relative to total coating composition weight. Notably, for component wt% listed are for the active solids and the water component is included in the water wt%.Coat Weight DeterminationDetermine the coat weight for coatings on a substrate after curing and drying by measuring the silicon content on the coating using X-Ray fluorescence (XRF). Use an Oxford lab-x35OO XRF Analyzer after silicon elemental calibration with sample standards. Measure a blank substrate and then take 3 measurements of a coated substrate. Average the silicon content from the three measurements and determine a coat weight in terms of grams coating per square meter of coating (g / m2). Determine coat weight from a calibration curve derived from the sample standards prepared by coating substrates with different thicknesses of the coating, determining the thickness by ellipsometry and correlating the thickness to silicon concentration by XRF. The silicon coat weight for all samples are in a range of 0.35 to 0.6 g / m .ExtractablesDetermine extractables for a sample as the percent coat weight lost after immersion in methyl isobutyl ketone (MIBK). MIBK dissolves uncured silicone, so the test measures extent of cure for the coating. Determine percent coat weight lost by determining coat weight directly after curing and again after immersion in MIBK and then dividing the difference between the coat weights by the coat weight before immersion in MIBK and multiplying by 100%. Determine extractables immediately after curing and drying (immediate value) and again after allowing the sample to age for 24 hours at 23-25 °C (24-hour value). For the present invention it is desirable to have an immediate value of less than 15% and a 24-hour value of less than 10%.Water Resistance (Cobb60 Test)Determine the water resistance of samples using the conventional Cobb test for absorption described in TAPPI 441 om-04 test method (TAPPI Cobb Test). Expose coated substrate samples to water for 45 seconds, then remove from the water over 15 seconds and then measure the mass of water absorbed after the full 60 seconds (mass after water absorption - mass before water absorption). The Cobb60 value is the mass of water absorbed after 60 seconds divided by the area of the sample in square meters and is reported in units of grams water persquare meter of sample (g / m ). For the present invention it is desirable to have a Cobb60 value that is less than 18 g / m2.Grease Resistance (3M KIT Test)Determine grease resistant for samples following 3M KIT test described in TAPPI 559 cm- 12 procedure: “Grease Resistance Test for Paper and Paperboard.” A drop of a fresh KIT solution (KIT number 1 to 12 from least to most aggressive) made from a combination of Castor oil, n-heptane and toluene at various ratios, was placed on a sample. After wiping the drop off with a clean tissue, immediately examine the area. Failure for a particular drop is evidenced by dark staining of the area. Start with the most aggressive fluid (12) and work down on fluid rating until a fluid “passes” (no staining). The highest number fluid that passes corresponds to the 3M KIT rating for the sample. For the present invention it is desirable to have a 3M KIT rating of 6 or higher.Bakery Release (Anti-Stick Test)Determine baking residue using a Bakery Release test. The test measure the quantity of food left on a sample after oven baking and release. Samples of coated substrate are weighed to get an initial mass and folded into moulds . The moulds are 19 centimeter (cm) x 22 cm flat sheets that are folded to provide 2 cm high wall, with a container dimension that is 15 cm x 18 cm. Process cakes containing 4 eggs, 80 grams (g) of sugar, 80 g of potato flour, 85 g of wheat flour, and 5.5 g of baking powder at room temperature using a universal kitchen machine and place 100 (+ / - 2) grams of the batter into a mould prior to oven baking for 8 minutes at 205 °C. Remove the baked samples and allow to cool at room temperature (23-25 °C) for 2 minutes. Remove the cakes from the coated substrate samples and then measure the mass of the coated substrate sample including any cake still adhering to the coated substrate samples to get a postbaked mass. Determine mass of residual cake by subtracting the sample initial mass from the post-baked mass. Report the mass of cake still adhering (baking residue) as a mass per unit area of sample (g / m ). For the present invention it is desirable to have baking residue mass of less than 11 g / m2.Anchorage (Silicon Abrasion Resistance Test)Determine abrasion resistance using an Anchorage, or Silicone Abrasion Resistance Test. Determine silicon content of a cured and dried coating on a substrate using XRF as described for determining coating weight before and after subjecting the coating to rub-off using an abrasion tester such as Elcometer 1720. Subject the coating to 40 rub-off linear movementswith a flamed synthetic felt from Ideal Felt. The percent silicon remaining on the sample after rub-off is reported as the abrasion resistance value. For the samples of the present invention a value of 90% or more is desirable.Air Resistance (Gurley Air Permeability Test)Characterize the air resistance of each sample using a standard test method such as TAPPT 536 om-12 “Resistance of paper to passage of air (high-pressure Gurley method)”. Use an L&W Air Permeance Tester by sensing the air flow through a sample and the pressure difference across the two sides of the sample. Measure air permeance (permeability) as time expressed in Gurley seconds or Gurley units for a given volume of air to pass through a test sample using a pressure differential of approximately 3 kiloPascals. The higher the air permeance time in Gurley, the lower the air permeability of a sample and the better the sample’s barrier properties towards air and more generally towards gas. For the present invention it is desirable to have a Gurley value of 10,000 seconds or higher.RESULTSCE1 presents a base curable coating composition without any starch. It fails to meet coating performance targets for 3M KIT and Gurley.CE2 presents the base curable coating composition with OSA but no starch. It fails to meet coating performance targets for 3M KIT, Gurley, and Baking Residue.CE3 presents a non-curable coating of just water and starch. It fails to meet coating performance targets for COBB60, 3M KIT and Baking Residue.CE4 presents CE3 with OSA. It fails to meet coating performance targets for COBB60, 3M KIT and Baking Residue.CE5 presents a non-curable coating of just water and an alkenyl succinic anhydride- modified starch. It fails to meet coating performance targets for COBB60, 3M KIT, Gurley, and Baking Residue.CE6 presents the base curable coating composition with non-modified starch. It fails to meet coating performance targets for 3M KIT.CE7 presents CE6 with twice as much non-modified starch. It fails to meet coating performance targets for abrasion resistance and 3M KIT.CE8 presents CE6 with three times as much non-modified starch. It fails to meet coating performance targets abrasion resistance and baking residue.CE9 presents CE8 with OSA included with non- modified starch, but not bound to the non-modified starch as a modifier. It fails to meet coating performance targets for abrasion resistance.CE10 presents a sample similar to CE1 except with a lower coat-weight. It fails to meet 3M KITT and Gurley performance targets.CE1 1 , CE 12, and CE13 present formulations of the various modified starch components at increasing DS values but without including a silicone base. The samples show that the starch coatings fail to meet the performance targets for Cobb60, 3M Kitt, Gurley, and Baking Residue.Ex 1 , Ex 2 and Ex 3 present three compositions of the base curable coating composition, but with three levels of an alkenyl succinic anhydride-modified starch included. Each of those coating compositions meet all of the coating performance targets.Ex 4, Ex 5, Ex 6, Ex 7, and Ex 8 present compositions of the present invention that contain alkenyl succinic anhydride-modified starch with different degrees of substitution (DS) values. Each of those coating compositions meet all of the coating performance targets.Table 5* These are aqueous compositions as described in Table 1. Values here are wt% of solids (“actives”) of this component with the water portion included in wt% of water. NM =Coat weight values could not be measured for these samples because they do not contain silicon. NT= not testedTable 6* These are aqueous compositions as described in Table 1. Values here are wt% of solids (“actives”) of this component with the water portion included in wt% of water. NM =Coat weight values could not be measured for these samples because they do not contain silicon.

Claims

CLAIMS:

1. A coating composition comprising the following components:(a) alkenyl-functional siloxane polymer with an average of at least two silicon- bonded alkenyl groups per molecule;(b) SiH-functional siloxane polymer containing an average of at least two SiH functionalities per molecule;(c) optionally, a non-reactive siloxane polymer;(d) hydrosilylation catalyst;(e) optionally, hydrosilylation reaction inhibitor;(f) surfactant;(g) an acid / base buffer that maintains a coating composition pH of less than 7 ;(h) alkyl and / or alkenyl succinic anhydride-modified starch;(i) water;(j) optionally, biocide; and(k) optionally, antifoam; where the molar ratio of SiH from component (b) to alkenyl groups from component (a) is in a range of 1.2 to 3.0.

2. The coating composition of claim 1, wherein the coating composition comprises water at a concentration in a range of 20 to 95 weight-percent and total siloxane polymer as a sum of components (a), (b) and (c) that is in a arrange of 2 to 20 weight-percent, and an alkyl and / or alkenyl succinic anhydride-modified starch at a concentration in a range of 0.45 to 18 weight-percent, with weight-percent relative to coating composition weight.

3. The coating composition of any one previous claim, wherein the anhydride-modified starch is octenylsuccinic anhydride modified starch.

4. The coating composition of any one previous claim, wherein the alkenyl-functional siloxane polymer is a linear vinyl end-capped siloxane polymer.

5. The coating composition of any one previous claim, wherein the non-reactive siloxane polymer is trimethyl endblocked polydimethyl siloxane.

6. The coating composition of any one previous claim, wherein the coating composition is free of ethylene vinyl alcohol copolymers and ethylene- vinyl ester copolymers.

7. The coating composition of any one previous claim, wherein the coating composition comprises at least two separate parts that remain distinct from one another until blended to form a single coating composition, the separate parts comprising:(a) a first part that is a base emulsion and / or dispersion comprising: (i) water; (ii) surfactant; (iii) alkenyl -functional siloxane polymer; (iv) SiH-functional siloxane polymer; and (v) optionally, non-reactive siloxane polymer;(b) a second part that is a catalyst emulsion and / or dispersion comprising: (i) water, (ii) surfactant, (iii) alkenyl-functional siloxane polymer, and (iv) hydrosilylation catalyst;(c) optionally, a third part that is an antifoam emulsion; and wherein, the anhydride-modified starch can be a separate part or can be included in one of the other parts and the remaining components can be in either one or both of the first part or second part.

8. A process for making a non-stick coating, the process comprising combining the components of the coating composition of any one previous claim together to form a mixture, coating a substrate with the mixture to form a coating on the substrate, and then curing the coating.

9. The process of claim 8, wherein the process comprises providing the coating composition of claim 7 and then mixing the components together to form the dispersion of claim 8.

10. An article comprising a substrate coated with the coating composition of any one of claims 1-7, where the coating composition has undergone curing by a hydrosilylation reaction between the alkenyl-functional siloxane polymer and the SiH-functional siloxane polymer.

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