Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/10—Coatings without pigments
  • D21H19/14—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/46—Non-macromolecular organic compounds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/10—Packing paper

Definitions

• 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.
• 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 C 18 -C 36 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
• 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
• 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.
• said diglycerides comprise 20-80% of said mixture
• said triglycerides comprise 0-50% of said mixture.
• 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
• the fatty acids are from any vegetable or animal glyce ⁇ de oils or mixtures thereof
• vegetable or animal glyce ⁇ de 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
• 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
• the paper is selected from the group consisting of single sheets of paper, flexible paper and non-flexible paper
• the packaging mate ⁇ al compnsing a substrate compnsing the coating composition is water repellant
• 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-
• said diglycerides comprise 20-80% of said mixture, and, said triglycerides comprise 0-50% of said mixture.
• glycerol comprises 0-5% of the mixture.
• monoglycerides comprise 25-50% of said mixture.
• diglycerides comprise 30-60% of said mixture.
• triglycerides comprise 3-20% of said mixture.
• glycerol comprises 0-2% of said mixture.
• the fatty acids are from any vegetable or animal glyceride oils or mixtures thereof.
• 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.
• the mixture comprises 0-5% glycerol.
• the coating composition is mixed with one or more materials that do not change the melting properties of said coating composition.
• 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.
• 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.
• the composition comprises said mixture and further comprises one or more of hydrogenated oils, waxes from vegetable, animal, insect, mineral or synthetic sources.
• 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.
• 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.
• 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.
• 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.
• DSC Differential Scanning Calorimetry
• 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.
• 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.
• 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.
• the coating system can also be prepared from fatty acids.
• 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.
• water-resistant paper and paperboard articles have been used as wrapping or packaging for moist or wet foods, many of which are refrigerated.
• 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.
• 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.
• 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-
• 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.
• 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.
• the paper 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-
• 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.
• the coating composition 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.
• 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.
• 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
• the pigments are typically applied m the form of an aqueous suspension or dispersion of pigment material in the bmder or adhesive composition
• 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 unde ⁇ vatized 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
• the water vapor barner level of coatmgs which act as a moisture vapor barrier are generally between 1-6 g/100 in 2 /24 hrs at 100 °F/90% RH (relative humidity) -14-
• MVTR Magnetic Vapour Transition Rate
• 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.
• 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-
• the provision of water repellant surfaces on both the mte ⁇ or 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
• 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
• 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
• 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
• T 0 , 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 T 0 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.
• 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.

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• Paper (AREA)
• Paints Or Removers (AREA)
• Laminated Bodies (AREA)
• Wrappers (AREA)

Applications Claiming Priority (3)

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• 2000
  • 2000-12-07 CA CA002394288A patent/CA2394288A1/en not_active Abandoned
  • 2000-12-07 EP EP00982483A patent/EP1261672A2/de not_active Withdrawn
  • 2000-12-07 AU AU19508/01A patent/AU1950801A/en not_active Abandoned
  • 2000-12-07 WO PCT/US2000/033119 patent/WO2001044420A2/en not_active Application Discontinuation

Non-Patent Citations (1)

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