EP1261672A2

EP1261672A2 - Glyceride oil based coating waxes

Info

Publication number: EP1261672A2
Application number: EP00982483A
Authority: EP
Inventors: Inmok Lee
Original assignee: Archer Daniels Midland Co
Current assignee: Archer Daniels Midland Co
Priority date: 1999-12-17
Filing date: 2000-12-07
Publication date: 2002-12-04
Also published as: AU1950801A; WO2001044420A2; CA2394288A1; WO2001044420A3

Abstract

This invention relates, in general, to a coating system which is a natural, renewable, healthier replacement of paraffin wax for paper coating application. The coating system is made from glyceride oils and is free of mineral hydrocarbons and their derivatives. More specifically, the present invention relates to packaging material comprising a substrate comprising a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise 20-80% of said mixture, said diglycerides comprise 20-80% of said mixture, and, said triglycerides comprise 0-50% of said mixture. In a preferred embodiment, the glyceride oils are vegetable oils.

Description

For two-letter codes and other abbreviations, refer to the "Guidance Notes on Codes and Abbreviations" appearing at the beginning of each regular issue of the PCT Gazette

Glyceride Oil Based Waxes

Background of the Invention

Field of the Invention

The field of this invention relates to a coating system which is made from glyceride oils derived from vegetable or animal sources. The field of this invention more particularly relates to the use of vegetable oils, and glyceride mixtures thereof, as replacement for paraffin wax.

Related Art

Refined paraffin wax is currently being used in many food applications, such as coating foods and packaging materials. The use of paraffin wax in food packaging industry includes coatings for a wide variety of paper, film, cups, containers and board.

Paraffin wax is a petroleum wax, which is made from slack wax, a byproduct of lubricating oil, through a series of refining steps. Chemical composition of paraffin wax is complex but generally composed of 40-90 wt-% normal alkanes, with the remainder C₁₈-C₃₆ isoalkanes and cycloalkanes. Fully refined paraffin contains less than 1 wt-% oil, which is low molecular weight hydrocarbons. The use of paraffin wax in food application is regulated by the

United States Food and Drug Administration (FDA). Recently, health issues of paraffin wax, especially in food applications, became a concern. Some studies found the tendency of certain organs to retain paraffin. Some predict that paraffin wax may be phased out of food packaging application.

French patent EP 0 811 664 Al relates to glyceride based oils used as components for a paper coating material. The coating material requires 3-30 wt

% rosin. The coating material is prepared by a series of mixing of all the components, including commercial mono- and diglyceride products. Rosin is not on the generally recognized as safe (GRAS) list promulgated by the FDA.

USPN 5,635,279 to Ma et al. relates to repulpable, water repellant paperboard. The paperboard has a water-repellant coating which includes a polymer matrix/wax/pigment mixture and is applied to the paperboard as an aqueous formulation. The wax component may be a wax emulsion based on camauba wax, camauba/paraffiin wax, carnauba/microcrystalline and carnauba/polyethylene resin.

Summary of the Invention

It is a general object of this invention to provide a coating system which is a natural, renewable, healthier replacement of paraffin wax for paper coating applications.

It is a specific object of this invention to provide packaging material comprising a substrate comprising a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise 20-80% of said mixture, said diglycerides comprise 20-

80% of said mixture, and said triglycerides comprise 0-50% of said mixture.

It is another specific object of this invention to provide a substrate comprising a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise

20-80% of said mixture, said diglycerides comprise 20-80% of said mixture, and, said triglycerides comprise 0-50% of said mixture.

It is another specific object of this invention to provide a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise 20-80% of said mixture, said diglycerides comprise 20-80% of said mixture, and, said triglycerides comprise 0-50% of said mixture. It is another specific object of this invention to provide a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise about 30-45% of said mixture, said diglycerides comprise about 40-60% of said mixture, said triglycerides comprise about 5-15% of said mixture, and said glycerol comprises about 0-2% of said mixture.

It is another specific object of this invention to provide a method of rendering a substrate water repellant and/or providing moisture vapor barrier properties to said substrate, comprising applying to said substrate an amount of the coating composition that is sufficient to render said substrate water repellant and/or provide moisture vapor barrier properties thereto- Further object and advantages of the present invention will be clear from the description that follows.

Brief Description of the Figures

FIG. 1. Differential scanning calorimetry (DSC) thermogram of commercially available paraffin wax.

FIG. 2. Differential scanning calorimetry (DSC) thermogram of glyceride wax prepared in Example 1.

FIG. 3. Differential scanning calorimetry (DSC) thermogram of triglycerides of saturated fatty acids from soybean oil.

FIG. 4. Differential scanning calorimetry (DSC) thermogram of a 1 : 1 mixture of the glyceride wax prepared in Example 1 and partially hydrogenated soybean oil (IV about 20). Definitions

In the description that follows, a number of terms used in the coating field are extensively utilized. In order to provide a clear and consistent understanding of the specification and the claims, the following definitions are provided. Water repellant. As used herein, the term " water-repellant" merely refers to the hydrophobic character of the coating and its tendency to repel, block or not significantly absorb or transmit water in normal use. Thus, the term "water- repellant" is intended to include "water-resistant" and other terminology which connotes substantial as opposed to total or complete water blocking properties, and refers to a water-blocking property which is sufficient for the intended use requiring a degree of water-repellency. For the purposes of this invention, "water-resistant" or "water-resistant coatings or compositions" shall mean a composition used as a coating which provides a fully-coated or impregnated substrate with sufficient resistance to water that the substrate' s physical properties such as physical strength and fiber integrity are not significantly degraded after immersion in ice water (0°C) for a one hour period.

Moisture vapor barrier. As used herein, the term "moisture vapor barrier" refers to a barrier to gases, moisture and aromas as well as traditionally defined vapors. The term "vapor" implies a liquid at partial pressure, such as water vapor. The term "gas" includes oxygen, nitrogen, carbon dioxide and others. "Aroma" includes those materials which bear a fragrance, for example, menthol and others.

Detailed Description of the Preferred Embodiments

The disclosed invention relates to a coating system which is a natural, renewable, healthier replacement of paraffin wax for paper coating application.

The coating system disclosed below, of which all the components are from glyceride oils, performed very well for paper coating applications. The coating system is made from glyceπde oils and is free of mineral hydrocarbons and their derivatives

An object of the present invention is to provide packaging material comprising a substrate comprising a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise 20-80% of said mixture, said diglycerides comprise 20- 80% of said mixture, and, said triglycerides comprise 0-50% of said mixture In one embodiment, glycerol comprises 0-5% of the mixture In a preferred embodiment, monoglycerides comprise 25-50% of said mixture In a preferred embodiment, diglycerides comprise 30-60% of said mixture In a preferred embodiment, triglycerides comprise 3-20% of said mixture In another embodiment, glycerol comprises 0-2% of said mixture

In a preferred embodiment, the fatty acids are from any vegetable or animal glyceπde oils or mixtures thereof In a particularly preferred embodiment, vegetable or animal glyceπde oils are selected from the group consisting of soy, canola, palm, rapeseed, cottonseed, coconut, crambe, com oil, fish oil, lard, beef tallow, refined forms of any of the preceding natural oils, partially hydrogenated forms of any of the preceding natural oils, and mixtures thereof

In a preferred embodiment, the substrate is selected from the group consisting of paper, paper board, food and beverage containers, paper board containers, corrugated paper, fiber cans, fiber tubes, and cellulosic fibers

In another preferred embodiment, the paper is selected from the group consisting of single sheets of paper, flexible paper and non-flexible paper

In a preferred embodiment, the packaging mateπal compnsing a substrate compnsing the coating composition is water repellant In another preferred embodiment, the packaging matenal comprising a substrate compnsing the coating composition has moisture vapor barrier properties

It is also an object of the invention to provide a substrate compnsing a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycendes compnse 20-80% of said -6-

mixture, said diglycerides comprise 20-80% of said mixture, and, said triglycerides comprise 0-50% of said mixture. In one embodiment, glycerol comprises 0-5% of the mixture. In a preferred embodiment, monoglycerides comprise 25-50% of said mixture. In a preferred embodiment, diglycerides comprise 30-60% of said mixture. In a preferred embodiment, triglycerides comprise 3-20% of said mixture. In another embodiment, glycerol comprises 0-2% of said mixture. In a preferred embodiment, the fatty acids are from any vegetable or animal glyceride oils or mixtures thereof. In a particularly preferred embodiment, vegetable or animal glyceride oils are selected from the group consisting of soy, canola, palm, rapeseed, cottonseed, coconut, crambe, com oil, fish oil, lard, beef tallow, refined forms of any of the preceding natural oils, partially hydrogenated forms of any of the preceding natural oils, and mixtures thereof. In a preferred embodiment, the substrate is food, a pharmaceutical agent, cosmetics, or, flooring material. It is also an object of the invention to provide a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise 20-80% of said mixture, said diglycerides comprise 20-80% of said mixture, and, said triglycerides comprise 0-50% of said mixture. In one embodiment, the mixture comprises 0-5% glycerol. In another embodiment, the coating composition is mixed with one or more materials that do not change the melting properties of said coating composition. In one embodiment, the materials are selected from the group consisting of soy lecithin, partially hydrogenated oils, interesterified oils, and waxes from vegetable, animal, insect, mineral or synthetic sources. In another embodiment, the monoglycerides and diglycerides are acetylated.

It is another object of the invention to provide a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise about 30-45% of said mixture, said diglycerides comprise about 40-60 % of said mixture, said triglycerides comprise about 5-15% of said mixture, and said glycerol comprises about 0-2% of said mixture. In one embodiment, the composition comprises said mixture and further comprises one or more of hydrogenated oils, waxes from vegetable, animal, insect, mineral or synthetic sources. In a prefened embodiment, the coating composition comprises about 50% of the coating composition wherein the remainder of the composition is comprised of materials that do not change the melting properties of said coating composition. In another preferred embodiment, said one or more materials are selected from the group consisting of soy, canola, palm, rapeseed, cottonseed, coconut oil, corn oil, crambe, fish oil, lard, beef tallow, refined forms of any of the preceding natural vegetable oils, partially hydrogenated forms of any of the preceding natural vegetable oils, waxes from vegetable, animal, insect, mineral or synthetic sources, and mixtures thereof.

It is another object of the invention to provide a method of rendering a substrate water repellant and/or providing moisture vapor barrier properties to the substrate, comprising applying to the substrate an amount of the coating composition of the invention that is sufficient to render the substrate water repellant and/or to provide the substrate with moisture vapor barrier properties. In one embodiment, the substrate is selected from the group consisting of paper, paper board, food and beverage containers, fiber cans, fiber tubes, paper board containers, corrugated paper, and cellulosic fibers. In another embodiment, the paper is selected from the group consisting of single sheets of paper, flexible paper and non-flexible paper.

The coating system that is disclosed in this invention has very similar thermal properties as that of paraffin wax for paper coating. Paraffin wax for paper coating requires certain melting characteristics dependent upon the quality of the paper and the economics of the production. Low melting components in the wax make the coated papers oily. Too high-melting wax is not favorable economically because of higher energy consumption. When the cunent commercial paraffin wax was analyzed by Differential Scanning Calorimetry (DSC) the paraffin wax started to melt at 29 °C and melted completely at 67.2° C, with the melting peak at 60.4°C. (See, FIG. 1.) Non brittleness is also an important quality of the wax material. The coating system was much less brittle than the other glyceride based waxes, such as hydrogenated vegetable oil.

Basically the coating composition is compnsed of mixtures of mono-, di- and triglycerides of saturated chain fatty acids. Monoglycerides comprise 20-80 (preferably 25-50%). Diglycerides comprise 20-80% (preferably 30-60%).

Triglycerides comprise 0-50% (preferably 3-20%). Glycerol can comprise 0-5% (preferably 0-2%). The diverse composition of the system also makes the invented material much less brittle.

The systemcan be prepared directly by transesterification of hydrogenated glycerides and glycerol, which is more favorable economically than, as in the

French patent, mixing the components manufactured by transesterification. Mixing the components of the coating system is an alternative way for the preparation of the claimed coating system.

For the source of fatty acids, any vegetable or animal glyceride oils with medium, long chain fatty acids or very long chain fatty acids such as soy, canola, palm, rapeseed, cottonseed, coconut, crambe, com oil, lard, fish oil, beef tallow and mixtures of the oils, can be used for the hydrogenated glycerides. However, the coating system can also be prepared from fatty acids.

Other materials that do not change the melting property of the system can also be added for the coating application. For example, partially hydrogenated soy oil (Iodine Value (IV) about 20) was added (1 : 1) to the coating system, and the mixture also had favorable properties for paper coating. Other materials that can be combined include other partially hydrogenated oils (low IV), acetylated mono-/diglycerides, propylene glycol esters, ethylene glycol esters and other resin materials.

In one particularly preferred embodiment, the coating composition is about 39% monoglycerides, about 45% diglycerides, about 2% glycerol with the remainder being about 14% triglycerides. In another particularly preferred embodiment, the coating composition is about 33-36% monoglycerides, about 54- 57% diglycerides, about 3-5% triglycerides and about 1-3% glycerol. For quite some time, water-resistant paper and paperboard articles have been used as wrapping or packaging for moist or wet foods, many of which are refrigerated. For example, corrugated paperboard containers are cascade-coated or curtain- coated with paraffin wax-based compositions applied by passing the corrugated paper containers beneath a curtain of molten paraffin wax. These water-resistant containers are then used for packaging produce, meats, poultry and fish that must be refrigerated. Often the containers themselves are filled with ice in addition to the food itself. Ordinary untreated paperboard containers cannot withstand such exposure to water. Ecological concerns have focused on disposal of water-resistant paper and corrugated paper containers because landfills have been filling up at an alarming rate. If such containers could be recycled, this would reduce the amount of waste containers that must be placed in landfills as well as the amount of virgin timber needed to produce the paper. Water-based coatings do provide these advantages, but their use requires a change in the type of coating equipment used to manufacture coated, water- resistant paper, paperboard and corrugated paper containers. In practice, these coatings do not have sufficient water resistance to withstand long periods of exposure to ice water such as is required for produce or meat containers. Use of water-based coatings on hydrophilic substrates such as corrugated paper produces a wet surface that must then be dried by the application of heat. The coating system of the present invention provides a substitute for wax components in the water-based coatings.

Hot melt coatings are typically solvent-free and applied at 60°-95°C depending upon the type of water-resistant agent being used. Hot melt coatings immediately solidify as they cool below their melting point. Thus, they do not require a significant further drying step of the type which may be necessary with water-based coatings. An increase in the drying time or energy needed to dry the coatings is a disadvantage because it increases cost and lengthens the time needed before the paper or corrugated paper containers can be handled. In a conventional -10-

cascade or curtain coating process, paper sheets are placed at one end of a cascade or curtain coating machine having a "curtain" or wall of molten wax coating that is poured continuously over the paper sheets passing through the curtain. After coating, the paper sheets pass through an area of the machine that has a fan to blow ambient air over the paper sheets and reduce their temperature to the point where the hot melt coating solidifies. The paper sheets are then simply removed from the other end of the machine. Thus, hot melt coatings have the advantage of being relatively easy to process. They do not require a change in coating equipment from the type of equipment already owned by many commercial manufacturers of coated paper and corrugated paper containers. These methods are known in the art.

Another object of this invention is to provide such coating compositions in a form that can be applied using conventional hot melt wax paper, paperboard and corrugated paper coating equipment such as curtain coating or cascade coating machinery. The coating compositions are applied using the same type of coating equipment as is conventionally used for hot melt wax coatings for paper- based products.

For example, the compositions of the present invention may be heated until the composition is sufficiently fluid to be coated such as from about 50 °C to 130°C, more preferably from about 60°C to 95 °C. The composition is added to a reservoir in a conventional cascade or curtain coating machine for flexible paper that are placed on a moving conveyor belt in flat sheet for A cascade or wall of molten coating composition is flowed over the tops of the sheets so the fluid composition coats all sides of the sheets. After passing through the curtain of molten hot coating composition, the paper sheets pass through a cooler area while air is circulated around the coated sheets to cool the composition below its melting point and create a solid coating on the sheets. The coated sheets are then removed from the conveyor belt. The remaining hot coating composition is captured after it passes over the sheets and is recirculated back over new sheets to form a continuous cascade coating process. Curtain coating machinery can -11-

also be used. Commercial coaters typically desire to have from about 30% to 80% coating pickup on the products being coated.

Various ways of evaluating the water resistance of coated paper products have been developed. One method is to calculate the percent coated substrate sample weight change after immersion in ice water (0°C) for a one hour period by weighing the coated substrate sample before and after coating, then weighing the coated substrate sample after immersion in water, calculating the difference in coated substrate sample weight before and after immersion, and dividing that difference by the uncoated substrate sample weight, and multiplying by 100 to get a percent weight change ("water immersion test"). A desirable value of water absorption or weight gain by the water immersion test is no more than about 10%, since above this value, the paper strength begins to deteriorate noticeably.

Substrates in the present invention comprise a fibrous web of cellulosic materials such as fiber cans and tubes and include a variety of coated and uncoated paper and paperboard, including bleached or unbleached hardwood or softwood, virgin or recycled and clay-coated or uncoated forms of paper or paperboard. Preferred application of the coating composition are to the surfaces of wet-strength or non-wet strength linerboards for use in agricultural box applications. Other alternate packaging embodiments include coatings providing high slip and improved release characteristics to the coated substrate surfaces. Thus, for instance, for shipping meat it may be desirable to apply the coating composition on the inside of the corrugated box for obtaining improved release properties at freezer conditions and coating the outside of the boxes with the coating composition to provide low slip characteristics desirable during shipping.

Other such variations and combinations are contemplated by the invention and depend on the application and the properties and characteristics desired for the packaging.

Pigments may be incorporated into the coating composition of the invention. Pigmented coatings are done to improve the printing quality of the -12-

original paper. The pigments are generally available commercially under various tradenames and from various manufacturers. Representative pigments that may be used include, but are not limited to, MicaWhite 200, available from Franklin Minerals, Denver, Colo.; Mica C-4000, available from KMG Minerals, Kings Mountain, N.C.; Vantalc 6H and PDX 181 slurry, both talcs which are available from R. T. Vanderbilt, Norwalk, Connecticut; Black Hills Bond, bentonite, available from Black Hills Bentonite, Mills, Wyo.; and Opazil AS, bentonite, available from Albion Kaolin Co., Hephziban, Ga. The physical characteristics and properties of these commercially available materials are further described in technical data sheets which are incorporated herein by reference.

The pigments are selected from the group consisting of aluminum trihydrate, barium sulfate, calcium carbonate, mica (potassium aluminum silicates), nepheline syenite (sodium potassium alumino silicate), finely ground silica sand and other natural and synthetic type of silicates, talc (magnesium silicates), wollastonite (calcium metasilicates), bentonite (montmorillonite, smectite) and clay.

Preferred pigments incorporated into the formulations include mica, talc, clay and bentonite and are considered "platelet" type of pigments based on their particle shape. However, other types of pigments may also be used. When platelet type pigments are incorporated into the composition formulations improved water (moisture) vapor barrier properties of the coatings is observed. This is believed to be due to the presence of a "tortuous path" created by the pigments.

The good water vapor barrier properties of the invention coatings are believed to be provided by the presence of this "tortuous path". The permeability of barrier membranes and the theory of "tortuous path" are discussed in an article entitled "Barrier Membranes" by E. L. Cussler et al, (Journal of Membrane Sciences 38: 161-174 (1988)) which is incorporated herein by reference. It is believed that the configuration of the polymer, wax and pigment components of -13-

the coatmg extend the diffusion path length and lengthens diffusion time which thus improves water barner properties

Hydrophobicity of the pigment mixtures can be adjusted by usmg highly hydrophobic pigments, 1 e , talc, mica, medium hydrophobic pigments, 1 e , wollastomte, nephekne syenite, finely ground silica and hydrophilic pigments, l e , clay, bentonite, calcium carbonate, aluminum trihydrate, banum sulfate

Typically, the pigments used m the mvention coatmgs have relatively low refractive mdex, meaning that the pigmented coatmgs will generally be transparent This has advantage when applied as an overcoat on a preprmted substrate surface Specifically, the mica, talc and bentonite pigments will not block the printing If desired, whiteness of the coatmg can be adjusted by usmg various amounts of titanium dioxide and calcium carbonate m combmation with the other pigments In alternate applications the pigment component may be excluded Pigmented coatings and layers typically compnse a pigment and a binder matenal. The pigments are typically applied m the form of an aqueous suspension or dispersion of pigment material in the bmder or adhesive composition In the coatmg, pigments are retained on the paper by means of bmders or adhesives, which are resms or polymers, that function as glue Paper coatmg bmders are derived from natural sources or made synthetically The largest volume, naturally denved, bmder is starch Starch may be used m either denvatrzed or undeπvatized form. The other mam natural bmder is protem prepared by extraction from soy meal Many other synthetic bmders or adhesives are known m the art Typically bmders or adhesives mclude starch, protems, styrene butadiene dispersions or lattices, polyvmyl acetate and lattices, acrylic lattices and others

Vanous ways for measuring moisture vapor (MVT) transmission have been developed The water vapor barner level of coatmgs which act as a moisture vapor barrier are generally between 1-6 g/100 in² /24 hrs at 100 °F/90% RH (relative humidity) -14-

MVTR ("Moisture Vapour Transition Rate") is measured at 23 °C, 85% RH (relative humidity)(temperate) or 38 °C 90% RH (relative humidity)(tropical) using a Lyssey L80 instrument calibrated daily against a standard PET film. The coated substrate samples are conditioned at room temperature for at least 24 h before starting MVTR measurement. Measurements are made at intervals until equilibrium is reached. Once equilibrium is reached, additional measurements are then made and the results averaged.

The grease resistance values (kit values) are generally dependable on the coating thickness applied to the substrate surface. The "Greaseproofness test" or "Kit value" is a test, described in Tappi 50( 10) 152A-153A (October 1967), standard RC 338 and UM511. The greaseproofness test permits measurement of the greaseproofness of materials towards mixtures of castor oil, toluene and heptane.

The test consists of gently placing some drops of these mixtures onto the paper treated. The drops are allowed to stay on the paper for 15 seconds, after which time the appearance of the papers or cardboard is carefully inspected and the wetting or penetration evidenced by browning of the surface are noted. The value corresponding to the mixture containing the highest percentage of heptane failing to penetrate or to wet the paper is the "kit value" of the paper and is regarded as the measure of oleophobic property of the paper treated. The higher the "kit value," the better is the oleophobic property of the paper. Typically the kit values for the composition coatings will range from 6-8, which will provide acceptable levels of grease resistance.

The coating composition of the present invention, which is high melting, can provide a protective layer against the penetration of low melting grease through the paper. Low melting grease is represented as castor oil, toluene and heptane in the grease resistance test.

Perishables and ice loaded within a container made from the packaging material of the invention will be adjacent the water-repellant inner surfaces of the container. This restricts penetration of water and other fluids such as blood or juices into the container. Likewise, the water repellant outer surfaces limit entry -15-

of water and other fluids mto the contamer to avoid contamination of the contents The provision of water repellant surfaces on both the mteπor and exterior of the contamer thus provides a contamer especially well suited for use where flow of fluid mto and out of the contamer is to be avoided The coatmg compositions of the mvention as discussed earlier may be applied by a number of different methods In addition they may be applied either on-corrugator or off-line In on-line corrugator application the coatmgs can be applied on both the wet- and dry- end of the corrugatoi This provides cost savmgs compared to an off-line coatmg application These processes however are more difficult to control than the off-line applications

In the wet end application process, the coatmg can be applied and dned prior to the smgle facer and after the double backer Additional drymg equipment is required for this type of application method In the dry end application process, coatmg can be applied after the hot plate section Residual heat m the paper dnes the coatmg Equipment used for wet end applications can mclude a rod coater, l e , MRC 1000, andablade coater, WEC-130S and WEC- 127, from Michelman, Inc Blade coaters such as DEC-500 and PDD/4 are designed for dry end applications by Michelman, Inc Such equipment is well known to those of skill m the art Vanous off-line coaters such as a rod coater, blade coater and air knife coater, known m the art, can be used to apply the mvention coatmgs The coatmg is preferably dried thoroughly after the application m order to prevent any sticking or blockmg within the coated rolls

The present mvention is descnbed m further detail m the following non- limiting examples

Examples

Thermal behavior of the wax matenals was analyzed by means of Parkin- Elmer Pynsl differential scanning calorimetry (DSC) DSC is a good mdicatoi -16-

of thermal properties of the materials. In the DSC analysis, 5-12 mg samples were weighed and sealed in aluminum pans, and an empty aluminum pan was used as a reference. The samples were cooled to -30°C and held until the heat flow stabilized. Then, samples were heated from -30°C to 100°C at 10°C/min. The melting transition of the sample is displayed as peaks. T₀ (onset temperature) in the thermogram of paraffin wax (FIG. 1) can be interpreted as the temperature at which the paraffin wax is starting to melt. T_P is the melting peak temperature. T_c is the temperature at which the sample is completely melted. T₀, T_P and T_c are important parameters for the melting characteristic of the material. T₀, T_P and T_c of the paraffin wax were 29.2, 60.4 and 67.2°C, respectively, while those of the material prepared in Example 1 (FIG. 2, good glyceride wax) were 30.8, 62.2 and 65.4°C. It is not desirable to have a melting transition below 30 °C, because that material can be oily at room temperature. It is also desirable to have a broader melting range (between T₀ and T_c), because a broader melting range is one indicator for non-brittleness. For example, the thermogram of the triglycerides of saturated fatty acids from soy oil (FIG. 3) had similar T_P and T_c as paraffin wax; however, it was very brittle, and the brittleness can be demonstrated as a narrow melting range, resulting in a sharp peak. However, a narrow melting range is not the only parameter that determines the brittleness. FIG. 4 shows desirable melting parameters. The sample was a 1: 1 mixture of the glyceride wax in Example 1 and partially hydrogenated soybean oil (IV about 20). The mixture sample was more brittle than DMG03-RM alone. Even though the mixture was more brittle, the mixture is suitable for use as a coating composition.

Example 1

400g fully hydrogenated soy oil was melted and mixed with 72g glycerol, before the mixture was dried at 100°C under 3-5 mmHg vacuum. The dried oil/ glycerol mixture was heated to 180°C. Then, 0.4g sodium hydroxide was added -17-

as a catalyst The reaction temperatuie was furthei mcreased to 220°C, and the reaction was contmued foi 40 mm with vigoious agitation and under nitrogen blanket 0 6g citric acid powder was added into the reaction mixtui e to neuti a ze the catalyst Aftei cooling the reaction mrxtuie to 165°C, extra glycerol was stripped off the reaction mixture under 3 5 mm Hg vacuum. The glyceiol- stnpped reaction mrxtuie was cooled to 90°C, filtered through a Grade 617 Ahlstrom Filter paper The glycende mixture had a thermal profile, by DSC, very similar to that of paraffin wax and performed well foi coatmg paper foi food wrappmg

Example 2

The matenal that was obtamed from the Example 1 was mixed with partially hydrogenated soy oil (lodme value about 20, hereafter, "IV20") at the ratio of 1 1 by weight The mixture also had a very similar DSC thermal profile as paraffin wax

Example 3

The material that was obtamed from Example 1 was further deodorized to improve the odor quality of it During the deodoπzation, the material was heated at 160°C for 30 mm, under 1-2 mm Hg vacuum, with about 5% steam sparged mto the material to help the removal of any odorous compounds The deodorized matenal had very mild odor The deodorized material had slightly lower monoglycerides than the material before the deodoπzation Also, the residual glycerol was almost completely removed from the matenal by deodoπzation However, there was no significant difference m the DSC thermal profiles between the materials before and after the deodoπzation It will be recognized by those skilled m the art that the coatmg compositions and coated substrates of the mvention have wide application m the -18-

production of packages or containers having water resistance. Advantageously, the coating compositions may also be used as oveφrint varnishes on preprinted linerboard substrates to impart additional scuff resistance to the coated substrate surface.

Having now fully described the present invention in some detail by way of illustration and example for puφoses of clarity of understanding, it will be obvious to one of ordinary skill in the art that same can be performed by modifying or changing the invention with a wide and equivalent range of conditions, formulations and other parameters thereof, and that such modifications or changes are intended to be encompassed within the scope of the appended claims.

All publications, patents and patent applications mentioned in this specification are indicative of the level of skill of those skilled in the art to which this invention pertains, and are herein incoφorated by reference to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incoφorated by reference.

Claims

-19-What Is Claimed Is:

1. Packaging material comprising a substrate comprising a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise 20-80% of said mixture, said diglycerides comprise 20-80% of said mixture, and, said triglycerides comprise 0-50% of said mixture.

2. The packaging material of claim 1 wherein said mixture comprises 0-5% glycerol.

3. The packaging material of claim 1 wherein said monoglycerides comprise 25-50% of said mixture.

4. The packaging material of claim 1 wherein said diglycerides comprise 30-60% of said mixture.

5. The packaging material of claim 1 wherein said triglycerides comprise 3-20% of said mixture.

6. The packaging material of claim 2 wherein said glycerol comprises

0-2% of said mixture.

7. The packaging material of claim 1 wherein said fatty acids are from any vegetable or animal glyceride oil or mixtures thereof.

8. The packaging material of claim 7 wherein said vegetable or animal glyceride oils are selected from the group consisting of soy, canola, palm, rapeseed, cottonseed, coconut, crambe. com oil, fish oil. lard, beef tallow, refined -20-

forms of any of the preceding natural oils, partially hydrogenated forms of any of the preceding natural oils, and mixtures thereof.

9. The packaging material of claim 1 wherein said substrate is selected from the group consisting of paper, paper board, food and beverage containers, fiber cans, fiber tubes, paper board containers, corrugated paper, and cellulosic fibers.

10. The packaging material of claim 9 wherein said paper is selected from the group consisting of single sheets of paper, flexible paper and non- flexible paper.

11. The packaging material of claim 1 wherein said coating composition is water repellant.

12. The packaging material of claim 1 wherein said coating provides moisture vapor barrier properties to said substrate.

13. A substrate comprising a coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise 20-80% of said mixture, said diglycerides comprise 20- 80% of said mixture, and, said triglycerides comprise 0-50% of said mixture.

14. The substrate of claim 13 wherein said mixture comprises 0-5% glycerol.

15. The substrate of claim 13 wherein said monoglycerides comprise

25-50% of said mixture. -21-

16. The substrate of claim 13 wherein said diglycerides comprise 30- 60% of said mixture.

17. The substrate of claim 13 wherein said triglycerides comprise 3- 20% of said mixture.

18. The substrate of claim 14 wherein said glycerol comprises 0-2% of said mixture.

19. The substrate of claim 12 wherein said fatty acids are from any vegetable or animal glyceride oil or mixtures thereof.

20. The substrate of claim 12 wherein said vegetable or animal glyceride oils are selected from the group consisting of soy, canola, palm, rapeseed, cottonseed, coconut, crambe, com oil, fish oil, lard, beef tallow, refined forms of any of the preceding natural oils, partially hydrogenated forms of any of the preceding natural oils, and mixtures thereof.

21. The substrate of claim 12 wherein said substrate comprises food. a pharmaceutical agent, cosmetics, or flooring material.

22. A coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise 20-80% of said mixture, said diglycerides comprise 20-80% of said mixture, and, wherein said triglycerides comprise 0-50% of said mixture.

23. The coating composition of claim 22 wherein said mixture comprises 0-5% glycerol. -22-

24. The coating composition of claim 22 wherein said composition is mixed with one or more materials that do not change the melting properties of said coating composition.

25. The coating composition of claim 24 wherein said materials are selected from the group consisting of soy lecithin, partially hydrogenated oils, interesterified oils, and waxes from vegetable, animal, insect, mineral or synthetic sources.

26. The coating composition of claim22 wherein said monoglycerides and diglycerides are acetylated.

27. A coating composition comprising a mixture of mono-, di- and triglycerides of saturated chain fatty acids, wherein said monoglycerides comprise about 30-45% of said mixture, said diglycerides comprise about 40-60 % of said mixture, said triglycerides comprise about 5-15% of said mixture, and said glycerol comprises about 0-2% of said mixture.

28. The coating composition of claim 27 wherein said composition comprises said mixture and further comprises one or more of hydrogenated oils, waxes from vegetable, animal, insect, mineral or synthetic sources.

29. A coating composition comprising about 50% of the coating composition of claim 27, wherein the remainder of the composition is comprised of one or more materials that do not change the melting properties of said coating composition.

30. The coating composition of claim 29 wherein said one or more materials is selected from the group consisting of soy, canola, palm, rapeseed, cottonseed, coconut oil, corn oil, crambe, refined forms of any of the preceding -23-

natural vegetable oils, partially hydrogenated forms of any of the preceding natural vegetable oils, waxes from vegetable, animal, insect, mineral or synthetic sources, and mixtures thereof.

31. A method of rendering a substrate water repellant and/or providing moisture vapor barrier properties to said substrate, comprising applying to said substrate an amount of the coating composition of claims 22, 27 or 29, that is sufficient to render said substrate water repellant and/or provide moisture vapor barrier properties thereto.

32. The method of claim 31 wherein said substrate is selected from the group consisting of paper, paper board, food and beverage containers, fiber cans, fiber tubes, paper board containers, corrugated paper, and cellulosic fibers.

33. The method of claim 32 wherein said paper is selected from the group consisting of single sheets of paper, flexible paper and non-flexible paper.