Patent Application
20200087047
Certain compounds and nutrients contained within packages can be negatively impacted by exposure to light. Many different chemical and physical changes may be made to molecular species as a result of either a direct, or indirect, exposure to light, which can collectively be defined as photochemical processes. As described in Atkins, photochemical processes can include primary absorption, physical processes (e.g., fluorescence, collision-induced emission, stimulated emission, intersystem crossing, phosphorescence, internal conversion, singlet electronic energy transfer, energy pooling, triplet electronic energy transfer, triplet-triplet absorption), ionization (e.g., Penning ionization, dissociative ionization, collisional ionization, associative ionization), or chemical processes (e.g., disassociation or degradation, addition or insertion, abstraction or fragmentation, isomerization, dissociative excitation) (Atkins, P. W.; Table 26.1 Photochemical Processes. Physical Chemistry, 5th Edition; Freeman: New York, 1994; 908.). As one example, light can cause excitation of photosensitizer species (e.g., riboflavin in dairy food products) that can then subsequently react with other species present (e.g., oxygen, lipids) to induce changes, including degradation of valuable products (e.g., nutrients in food products) and evolution of species that can adjust the quality of the product (e.g., off-odors in food products).
As such, there is a need to provide packaging with sufficient light protection properties to allow the protection of the package content(s) and sufficient mechanical properties to withstand shipping, storage, and use conditions.
The ability of packages to protect substances they contain is highly dependent on the materials used to design and construct the package (reference: Food Packaging and Preservation; edited M. Mathlouthi, ISBN: 0-8342-1349-4; Aspen publication; Copyright 1994; Plastic Packaging Materials for Food; Barrier Function, Mass Transport, Quality Assurance and Legislation: ISBN 3-527-28868-6; edited by O. G Piringer; A. L. Baner; Wiley-vch Verlag GmBH, 2000, incorporated herein by reference). Preferred packaging materials are designed with consideration for the penetration of moisture, light, and oxygen often referred to as barrier characteristics.
Light barrier characteristics of materials used for packaging are desired to provide light protection to package contents. Methods have been described to measure light protection of a packaging material and characterize this protection with a “Light Protection Factor” or (LPF) as described in commonly owned U.S. Pat. No. 9,638,679 “Methods for producing new packaging designs based on photoprotective materials”, the subject matter which is hereby incorporated by reference in its entirety.
Titanium dioxide (TiO2) is frequently used in plastics food packaging layer(s) at low levels (typical levels of 0.1 weight % to 5 weight % (“weight %” is abbreviated as “wt %” hereinafter) of a composition) to provide aesthetic qualities to a food package such as whiteness and/or opacity. In addition to these qualities, titanium dioxide is recognized as a material that may provide light protection of certain entities as described in, for example, U.S. Pat. Nos. 5,750,226; 6,465,062; and US 20040195141.
Useful packaging designs are those that provide the required light protection and functional performance at a reasonable cost for the target application. The cost of a packaging design is in part determined by the materials of construction and the processing required to create the packaging design.
Milk packaging is an application where there is a benefit for light protection in packages to protect milk from the negative impacts of light exposure. Light exposure to milk may result in the degradation of some chemical species in the milk; this degradation results in a decrease in the nutrient levels and sensory quality of the milk (e.g., “Riboflavin Photosensitized Singlet Oxygen Oxidation of Vitamin D”, J. M. King and D. B. Min, V 63, No. 1, 1998, Journal of Food Science, page 31). Hence protection of milk from light with light protection packaging will allow the nutrient levels and sensory quality to be preserved at their initial levels for extended periods of time as compared to milk packaged in typical packaging that does not have light protection (e.g., “Effect of Package Light Transmittance on Vitamin Content of Milk. Part 2: UHT Whole Milk.” A. Saffert, G. Pieper, J. Jetten; Packaging Technology and Science, 2008; 21: 47-55).
Additionally, multilayered structures are seen as a means to achieve light protection qualities in package designs. Typically, more than one layer of material is required for adequate protection of food from light and mechanical damage. For example, Cook et al. (U.S. Pat. No. 6,465,062) present a multilayer packaging container design to achieve light barrier characteristics with other functional barrier layers. Problems associated with multilayered packaging structures are they require more complex processing, additional materials for each layer, higher package cost, and risk delamination of layers. Deficiencies of multilayer designs and benefits of monolayer designs are discussed in US 20040195141 in section [0022] and [0026]. Moreover, state of the art caps comprising two or more layers of materials, such as a foil seal or light block liner, can achieve suitable light protection. However, these designs are deficient as the foil seal or liner layer may be removed or damaged after the package is opened by the consumer. These additional layers may be perceived by consumers as only part of the product sealing function. Thus, the consumer may remove them, perhaps so the layers or pieces of the layer do not fall into the product. Upon removal of such additional layer(s) the cap will not retain the light protection benefit provided by the layer(s) after the product is opened and the layer(s) is removed. Thus, such layer(s) may be used for sealing or other functions but are not a part of the light protection performance of the cap through consumer use.
Thus, there is a commercial need to create a monolayer food package that achieves, or exceeds, the light protection and mechanical strength properties of a multilayer package.
The present invention provides solutions to the above-identified deficiencies in the art by providing monolayer containers and monolayer closures that provide sufficient light protection and mechanical strength.
The invention comprises a light protection package that comprises a monolayer container and monolayer closure (e.g., a cap) that considers all portions of the light exposed package design, including all areas of the package that allow the potential for light exposure to the product contained within the package. For example, a light protection package according to the invention can be a light protection dairy container (e.g., a bottle) and removable and re-sealable closure (e.g., a cap). For optimal light protection performance, the container and closure can have substantially the same light protection performance or alternatively, when the light protection performance of the container and closure are different, the desired light protection performance should be met by the minimum performance level for either the container or closure.
The invention comprises a light protective package that comprises a monolayer container and a monolayer closure. The monolayer container and/or monolayer closure can comprise TiO2 particles. Moreover, the monolayer container and/or monolayer closure can further comprise at least one color pigment. The TiO2 particles and at least one color pigment can be dispersed throughout the container material and/or closure. The package has superior light protection properties while maintaining necessary mechanical properties. The monolayer container and/or monolayer closure can have a light protection factor (“LPF”) value of 20 or greater, preferably greater than 30, more preferably greater than 40, more preferably greater than 50, more preferably greater than 60, more preferably greater than 80, and even more preferably greater than 100.
In an aspect of the invention the monolayer closure comprises a top portion that is a sufficient thickness produced with light protection materials to provide light protection performance to the closure. In an aspect of the invention the monolayer closure top portion can have a thickness of at least about 50 mils.
The invention comprises a light protection package that comprises a monolayer container and monolayer closure (e.g., a cap) that considers all portions of the light exposed package design, including all areas of the package that allow the potential for light exposure to the product contained within the package. For example, a light protection package according to the invention can be a light protection dairy container (e.g., a bottle) and removable and re-sealable closure (e.g., a cap). For optimal light protection performance, the container and closure can have substantially the same light protection performance or alternatively, when the light protection performance of the container and closure are different, the desired light protection performance should be met by the minimum performance level for either the container or closure.
In this disclosure “comprising” is to be interpreted as specifying the presence of the stated features, integers, steps, or components as referred to, but does not preclude the presence or addition of one or more features, integers, steps, or components, or groups thereof. Additionally, the term “comprising” is intended to include examples encompassed by the terms “consisting essentially of” and “consisting of.” Similarly, the term “consisting essentially of” is intended to include examples encompassed by the term “consisting of.”
In this disclosure, when an amount, concentration, or other value or parameter is given as either a range, typical range, or a list of upper typical values and lower typical values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or typical value and any lower range limit or typical value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the disclosure be limited to the specific values recited when defining a range.
In this disclosure, terms in the singular and the singular forms “a,” “an,” and “the,” for example, includes plural references unless the content clearly dictates otherwise. Thus, for example, reference to “TiO2 particle”, “a TiO2 particle”, or “the TiO2 particle” also includes a plurality of TiO2 particles. All references cited in this patent application are herein incorporated by reference.
Monolayer is defined as a structural component of the package (e.g., the container and the closure (the closure may include threaded portion to assist in re-sealing the closure and container)) that is comprised of a single layer of material. The material in its cross section does not have differential layers with different compositions or functional properties. The monolayer is structural as it contains the contents of the package, however the package may be rigid (e.g., like a plastic bottle) or flexible (e.g., like a plastic pouch) or a combination of rigid and flexible portions.
Layers may be applied to the package components that are not structural. For example, decorative sleeves, stickers, wraps or print may be applied to cover portions of the package to provide branding, consumer information, and adjust the package texture and appearance. These layers are considered non-structural layers and thus a package comprising one or more components that are not structural is still considered monolayer in its structural design according to the invention.
A co-extruded package structure is not considered a monolayer package design according to the invention.
The removable and re-sealable closure (such as a bottle cap, which may comprise threads) may contain an optional insert which, if it can be readily removed, is also considered a layer that is nonstructural. For example, a cap may contain a layer to facilitate sealing of the package when the cap threads are engaged with a corresponding threaded portion of the container. Moreover, a cap or container may include a seal (e.g., foil or plastic) that is removed and discarded for normal consumer use of the package.
If a package container or closure contains a seal that is removed irreversibly for removal of the product from the package, then the container or closure is still considered to be a monolayer design. This seal that is removed is insufficient as a light protection layer as it is only available for light protection until the seal is removed. For example, a seal layer such as a plastic seal or a foil seal would be considered irreversibly removed layers.
If the seal is integrated into the cap it is not a monolayer cap according to the invention. Further if the cap contains another functional layer, such as an integrated oxygen scavenger layer or additional gasket-like material to improve the seal, it is not a monolayer cap. Aesthetic layers on the cap such as printed ink or stickers or partial coverage such as tamper evident rings can be used with a monolayer cap as the primary cap is still a single complete layer of material.
The invention comprises a light protective package that comprises a monolayer container and a removable and re-sealable monolayer closure (e.g., a cap). The monolayer container and/or monolayer closure can comprise TiO2 particles. Moreover, the monolayer container and/or monolayer closure can further comprise at least one color pigment. The TiO2 particles and at least one color pigment can be dispersed throughout the container material and/or closure. The package has superior light protection properties while maintaining necessary mechanical properties. The monolayer container and/or closure can have a light protection factor (“LPF”) value of 20 or greater, preferably greater than 30, more preferably greater than 40, more preferably greater than 50, more preferably greater than 60, more preferably greater than 80, and even more preferably greater than 100. A detailed description of LPF and measuring LPF values is described in commonly owned U.S. Pat. No. 9,638,679 “Methods for producing new packaging designs based on photoprotective materials” and U.S. Pat. No. 9,372,145 “Devices for determining photoprotective materials” the subject matter of both patents is incorporated herein by reference. Additional information may be found in the example sections of these patents. LPF values used herein are determined according to the teachings in these two patents.
The invention also comprises a monolayer closure comprising a top portion and side wall(s) portion. The closure top portion is a sufficient thickness produced with light protection materials to provide light protection performance to the closure. The closure top portion can have an LPF value of 20 or greater, preferably greater than 30, more preferably greater than 40, more preferably greater than 50, more preferably greater than 60, more preferably greater than 80, and even more preferably greater than 100. The monolayer closure additionally comprises light protection TiO2 materials. The monolayer closure provides suitable light protection performance in the closure top portion while overcoming injection molding closure production process challenges presented with the use of light protection materials at higher levels. This allows the processing performance of the injection molding equipment used to produce the closures to be maintained and the mechanical features (e.g., the threads on a screw top closure) of these closures to be produced with their desired functionality (e.g., sealing performance).
The monolayer closure can be used in conjunction with any container (e.g., a bottle). However, in an aspect of the invention the monolayer closure can be used in conjunction with a light protection container according to the present invention. Where the closure threads or side wall(s) engage or seal with the container, the primary container can provide light protection performance; however, as a monolayer, the top portion of the closure does not have any additional package layer to provide light protection and thus it must provide the light protection performance. Suitable light protection performance is achieved with the monolayer closure of the invention which comprises a thicker closure top portion (relative to the thickness of the cap side wall(s)) wherein light protection TiO2 materials are provided throughout the closure. In an aspect of the invention the closure comprises a top portion having a thickness of at least about 50 mil.
Although the closure of the present invention can be used with any suitable container, preferred containers include the containers of the present invention and additionally include the containers disclosed in commonly owned US20160083554, WO2016/196529, and PCT patent application PCT/US2017/066105, the subject matter of each is hereby incorporated by reference in their entirety.
Referring to the Figures, aspects of the invention will be described.
The titanium dioxide (and optionally at least one color pigment) can be dispersed and processed in package production processes by incorporating a masterbatch, and preferably processed into a package using blow molding methods and/or injection molding. The masterbatch can be solid pellets. The TiO2 (and optional color pigment) could also be delivered in other forms, such as in a liquid delivery form and do not have to be delivered in one single masterbatch formulation.
In an aspect of the invention the TiO2 particles can be coated with a metal oxide, preferable alumina, and then an additional organic layer. The treated TiO2 is an inorganic particulate material that can be uniformly dispersed throughout a polymer melt, and imparts color and opacity to the polymer melt. Reference herein to TiO2 without specifying additional treatments or surface layers does not imply that it cannot have such layers.
It is preferred that the metal oxide is selected from the group consisting of silica, alumina, zirconia, or combinations thereof. It is most preferred that the metal oxide is alumina. It is preferred that the organic coating material on the TiO2 is selected from the group consisting of an organo-silane, an organo-siloxane, a fluoro-silane, an organo-phosphonate, an organo-acid phosphate, an organo-pyrophosphate, an organo-polyphosphate, an organo-metaphosphate, an organo-phosphinate, an organo-sulfonic compound, a hydrocarbon-based carboxylic acid, an associated ester of a hydrocarbon-based carboxylic acid, a derivative of a hydrocarbon-based carboxylic acid, a hydrocarbon-based amide, a low molecular weight hydrocarbon wax, a low molecular weight polyolefin, a co-polymer of a low molecular weight polyolefin, a hydrocarbon-based polyol, a derivative of a hydrocarbon-based polyol, an alkanolamine, a derivative of an alkanolamine, an organic dispersing agent, or a mixture thereof. It is more preferred that the organic material is an organo-silane having the formula: R5xSiR64−x wherein R5 is a nonhydrolyzable alkyl, cycloalkyl, aryl, or aralkyl group having at least 1 to about 20 carbon atoms; R6 is a hydrolyzable alkoxy, halogen, acetoxy, or hydroxy group; and x=1 to 3. It is most preferred that the organic material is Octyltriethoxysilane. In a further aspect of the invention the metal oxide is alumina and the organic material is octyltriethoxysilane.
In an aspect of the invention the monolayer container and/or monolayer closure can have a concentration of TiO2 particles of from above 0 wt % to about 8 wt % of the monolayer, preferably 0.5 to 8 wt % of the monolayer, more preferably 0.5 to 4 wt % of the monolayer. In another aspect of the invention, the monolayer container and the monolayer closure can be comprised of different materials or different levels of the same or different materials. The melt processable resin(s) can be selected from the group of polyolefins. In an aspect of the invention the melt processable resin is preferably a high-density polyethylene and the monolayer container has a thickness of 8 mil to 50 mil, or more preferably 10 mil to 35 mil.
TiO2 particles may be in the rutile or anatase crystalline form. It is commonly made by either a chloride process or a sulfate process. In the chloride process, TiCl4 is oxidized to TiO2 particles. In the sulfate process, sulfuric acid and ore containing titanium are dissolved, and the resulting solution goes through a series of precipitation steps to yield TiO2. Both the sulfate and chloride processes are described in greater detail in “The Pigment Handbook”, Vol. 1, 2nd Ed., John Wiley & Sons, NY (1988), the teachings of which are incorporated herein by reference.
TiO2 particles may have a medium diameter range of about 100 nm to about 250 nm as measured by X-Ray centrifuge technique, specifically utilizing a Brookhaven Industries model TF-3005W X-ray Centrifuge Particle Size Analyzer. The crystal phase of the TiO2 is preferably rutile. The TiO2 after receiving surface treatments can have a mean size distribution in diameter of about 100 nm to about 400 nm, more preferably about 100 nm to about 250 nm. Nanoparticles (those have mean size distribution less than about 100 nm in their diameter) could also be used in this invention but may provide different light protection performance properties.
The TiO2 particles may be substantially pure, such as containing only titanium dioxide, or may be treated with other metal oxides, such as silica, alumina, and/or zirconia. TiO2 particles coated/treated with alumina are preferred in the present invention. The TiO2 particles may be treated with metal oxides, for example, by co-oxidizing or co-precipitating inorganic compounds with metal compounds. If a TiO2 particle is co-oxidized or co-precipitated, then up to about 20 wt % of the other metal oxide, more typically, 0.5 to 5 wt %, most typically about 0.5 to about 1.5 wt % may be present, based on the total particle weight.
The treated titanium dioxide can be formed, for example, by the process comprising: (a) providing titanium dioxide particles having on the surface of said particles a substantially encapsulating layer comprising a pyrogenically-deposited metal oxide or precipitated inorganic oxides; (b) treating the particles with at least one organic surface treatment material selected from an organo-silane, an organo-siloxane, a fluoro-silane, an organo-phosphonate, an organo-acid phosphate, an organo-pyrophosphate, an organo-polyphosphate, an organo-metaphosphate, an organo-phosphinate, an organo-sulfonic compound, a hydrocarbon-based carboxylic acid, an associated ester of a hydrocarbon-based carboxylic acid, a derivative of a hydrocarbon-based carboxylic acid, a hydrocarbon-based amide, a low molecular weight hydrocarbon wax, a low molecular weight polyolefin, a co-polymer of a low molecular weight polyolefin, a hydrocarbon-based polyol, a derivative of a hydrocarbon-based polyol, an alkanolamine, a derivative of an alkanolamine, an organic dispersing agent, or a mixture thereof; and (c) optionally, repeating step (b).
An example of a method of treating or coating TiO2 particles with amorphous alumina is taught in Example 1 of U.S. Pat. No. 4,460,655 incorporated herein by reference. In this process, fluoride ion, typically present at levels that range from about 0.05 wt % to 2 wt % (total particle basis), is used to disrupt the crystallinity of the alumina, typically present at levels that range from about 1 wt % to about 8 wt % (total particle basis), as the latter is being deposited onto the titanium dioxide particles. Note that other ions that possess an affinity for alumina such as, for example, citrate, phosphate or sulfate can be substituted in comparable amounts, either individually or in combination, for the fluoride ion in this process. The performance properties of white pigments comprising TiO2 particles coated with alumina or alumina-silica having fluoride compound or fluoride ions associated with them are enhanced when the coated TiO2 is treated with an organosilicon compound. The resulting compositions are particularly useful in plastics applications. Further methods of treating or coating particles of the present invention are disclosed, for example, in U.S. Pat. No. 5,562,990 and US 2005/0239921, the subject matter of which is herein incorporated by reference.
Titanium dioxide particles may be treated with an organic compound such as low molecular weight polyols, organosiloxanes, organosilanes, alkylcarboxylic acids, alkylsulfonates, organophosphates, organophosphonates and mixtures thereof. The preferred organic compound is selected from the group consisting of low molecular weight polyols, organosiloxanes, organosilanes and organophosphonates and mixtures thereof and the organic compound is present at a loading of between 0.2 wt % and 2 wt %, 0.3 wt % and 1 wt %, or 0.7 wt % and 1.3 wt % on a total particle basis. The organic compound can be in the range of about 0.1 to about 25 wt %, or 0.1 to about 10 wt %, or about 0.3 to about 5 wt %, or about 0.7 to about 2 wt %. One of the preferred organic compounds used in the present invention is polydimethyl siloxane; other preferred organic compounds used in the present invention include carboxylic acid containing material, a polyalcohol, an amide, an amine, a silicon compound, another metal oxide, or combinations of two or more thereof.
In a preferred embodiment, the at least one organic surface treatment material is an organo-silane having the formula: R5xSiR64−x wherein R5 is a nonhydrolyzable alkyl, cycloalkyl, aryl, or aralkyl group having at least 1 to about 20 carbon atoms; R6 is a hydrolyzable alkoxy, halogen, acetoxy, or hydroxy group; and x=1 to 3. Octyltriethoxysilane is a preferred organo-silane.
The following TiO2 pigments may be useful TiO2 particles in the present invention: Chemours Ti-Pure™ R-101, R-104, R-105, R-108, R-350, TS-1600, and TS-1601. Other TiO2 grades with similar size and surface treatments may also be useful in the invention.
When the TiO2 particles and color pigments are used in a polymer composition/melt, the melt-processable polymer that can be employed together with the TiO2 particles and color pigments comprise a high molecular weight polymer, preferably thermoplastic resin. By “high molecular weight” it is meant to describe polymers having a melt index value of 0.01 to 50, typically from 2 to 10 as measured by ASTM method D1238-98. By “melt-processable,” it is meant a polymer must be melted (or be in a molten state) before it can be extruded or otherwise converted into shaped articles, including films and objects having from one to three dimensions. Also, it is meant that a polymer can be repeatedly manipulated in a processing step that involves obtaining the polymer in the molten state.
Polymers that are suitable for use in this invention include, by way of example but not limited thereto, polymers of ethylenically unsaturated monomers including olefins such as polyethylene, polypropylene, polybutylene, and copolymers of ethylene with higher olefins such as alpha olefins containing 4 to 10 carbon atoms or vinyl acetate; vinyls such as polyvinyl chloride, polyvinyl esters such as polyvinyl acetate, polystyrene, acrylic homopolymers and copolymers; phenolics; alkyds; amino resins; polyamides; phenoxy resins, polysulfones; polycarbonates; polyesters and chlorinated polyesters; polyethers; acetal resins; polyimides; and polyoxyethylenes. Mixtures of polymers are also contemplated. Polymers suitable for use in the present invention also include various rubbers and/or elastomers, either natural or synthetic polymers based on copolymerization, grafting, or physical blending of various diene monomers with the above-mentioned polymers, all as generally known in the art. Typically, the polymer may be selected from the group consisting of polyolefin, polyvinyl chloride, polyamide and polyester, and mixture of these. More typically used polymers are polyolefins. Most typically used polymers are polyolefins selected from the group consisting of polyethylene, polypropylene, and mixture thereof. A typical polyethylene polymer is low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE). Additional polymers include, for example, polyethylene Terephthalate (PET, PETE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC, vinyl).
A wide variety of additives may be present in the package of this invention as necessary, desirable, or conventional. Such additives include polymer processing aids such as fluoropolymers, fluoroelastomers, etc., catalysts, initiators, antioxidants (e.g., hindered phenol such as butylated hydroxytoluene), blowing agent, ultraviolet light stabilizers (e.g., hindered amine light stabilizers or “HALS”), organic pigments including tinctorial pigments, plasticizers, antiblocking agents (e.g. clay, talc, calcium carbonate, silica, silicone oil, and the like) leveling agents, flame retardants, anti-cratering additives, and the like. Additional additives further include plasticizers, optical brighteners, adhesion promoters, stabilizers (e.g., hydrolytic stabilizers, radiation stabilizers, thermal stabilizers, and ultraviolet (UV) light stabilizers), antioxidants, ultraviolet ray absorbers, anti-static agents, colorants, dyes or pigments, delustrants, fillers, fire-retardants, lubricants, reinforcing agents (e.g., glass fiber and flakes), processing aids, anti-slip agents, slip agents (e.g., talc, anti-block agents), and other additives.
Any melt compounding techniques known to those skilled in the art may be used to process the compositions of the present invention. Packages of the present invention may be made after the formation of a masterbatch. The term masterbatch is used herein to describe a mixture of TiO2 particles and color pigments (collectively called solids) which can be melt processed at high solids to resin loadings (generally 50-80 wt % by weight of the total masterbatch) in high shear compounding machinery such as Banbury mixers, continuous mixers or twin screw mixers, which are capable of providing enough shear to fully incorporate and disperse the solids into the melt processable resin. The resultant melt processable resin product is commonly known as a masterbatch, and is typically subsequently diluted or “letdown” by incorporation of additional virgin melt processable resin in plastic production processes. The letdown procedure is accomplished in the desired processing machinery utilized to make the final consumer article, whether it is sheet, film, bottle, package or another shape. The amount of virgin resin utilized and the final solids content is determined by the use specifications of the final consumer article. The masterbatch composition of this invention is useful in the production of shaped articles.
In another embodiment of the present invention, the titanium dioxide and color pigment are supplied for processing into the package as a masterbatch concentrate. Preferred masterbatch concentrates typically have titanium dioxide content of greater than 40 wt %, greater than 50 wt %, greater than 60 wt %, greater than 70 wt %, or greater than 80 wt %. Preferred color concentrate masterbatches are solid. Liquid color concentrates and/or a combination of liquid and solid color concentrates could be used.
In an aspect of the invention, the amount of titanium dioxide particles in the package of the invention can be any suitable amount which results in the desired LPF value. For example, the amount of titanium dioxide particles contained in the container and/or closure can be at least about 0.5 wt %, and preferably at least about 0.1 wt %. In an aspect of the invention the titanium dioxide particles in the container and/or closure can be from about 0.5 wt % to about 20 wt %, and is preferably from about 0.1 wt % to about 15 wt %, more preferably 5 wt % to 10 wt %. In a further aspect of the invention the titanium dioxide particles in the container and/or closure can be from at least about 0.5 wt %, 0.6 wt %, 0.7 wt %, 0.8 wt %, 0.9 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt % to 12 wt %. In an aspect of the invention the titanium dioxide particles in the container and/or closure can be any amount between 0.1 wt % and 12 wt % (all wt % are based on the total weight of the monolayer of the container and/or closure).
A package is typically produced by melt blending the masterbatch containing the titanium dioxide and color pigment with a second high molecular weight melt-processable polymer to produce the desired composition used to form the finished monolayer package. The masterbatch composition and second high molecular weight polymer can be melt blended, using any means known in the art, as disclosed above in desired ratios to produce the desired composition of the final monolayer package. In this process, twin-screw extruders are commonly used. The resultant melt blended polymer is extruded or otherwise processed to form a package, sheet, or other shaped article of the desired composition. The melt blended polymer may be injection into a preform for subsequent stretch blow molding processing.
The package may have one or more additional functional layer or layers. Such layer or layers may be formed from a label, paper, printed ink, wrap, coating treatment or other material. The layer or layers may cover part or all of the surface of the package. The functional layer or layers may be on the internal walls of the package. The functional layer or layers may contribute some light protection performance to the package, but the primary light protection monolayer provides substantially more light protection than the light protection provided by the functional layer or layers.
Layers applied for aesthetic purposes, including for branding and product information like nutrition and ingredient labels, may not be complete layers. For example, labels may only cover a small area on the surface area of a package or a wrap may cover the sides of a package, but not the base. Such incomplete layers cannot provide fully effective light protection as light can enter the package through the surfaces of the package that are not covered by the layer. As light can enter the package from any direction, having complete coverage of the package is an important consideration in the package light protection design. Hence, aesthetic layers are often deficient in providing the primary mode of light protection for a package design. Functional layers typically have a narrowly defined purpose, such as providing gas barrier properties or to prevent interactions of layers or to bind two layers together and thus are not designed for light protection. The present invention addresses this challenge by providing and designing light protection directly into the primary package thus imparting light protection to substantially all of the package surface.
The monolayer container is provided with a removable and re-sealable monolayer closure (e.g., cap). In an aspect of the invention the monolayer closure can comprise substantially the same material as the monolayer container. In a further aspect of the invention the monolayer closure can be a different material from the monolayer container and can also be a different color than the monolayer container or the same color.
In an aspect of the invention, extrusion blow molding can be used to produce the monolayer container and/or monolayer cap. In yet another embodiment, a pre-form can be produced by injection molding used to produce the monolayer container and/or monolayer cap using a stretch blow molding process.
Blow molding is a molding process in which air pressure is used to inflate soft plastic into a mold cavity. Blow molding techniques have been disclosed in the art, for example in “Petrothene® Polyolefins . . . a processing guide”, 5th Edition, 1986, U.S.I Chemicals. Blow molding is an important industrial process for making one-piece hollow plastic parts with thin walls, such as bottles and similar containers. Blow molding is accomplished in two stages: (1) fabrication of a starting tube of molten plastic, called a parison, or an injection molded preform that is properly heated to a molten state; and (2) inflation of the tube or preform in a mold to the desired final shape. Forming the parison or preform is accomplished by either of two processes: extrusion or injection molding.
Extrusion blow molding contains four steps: (1) extrusion of parison; (2) parison is pinched at the top and sealed at the bottom around a metal blow pin as the two halves of the mold come together; (3) the tube is inflated so that it takes the shape of the mold cavity; and (4) mold is opened to remove the solidified part.
Injection blow molding contains the same steps as blow molding; however, is the injection molded preform is used rather than an extruded parison: (1) preform is injection molded; (2) injection mold is opened and preform is transferred to a blow mold; (3) preform is heated to become molten and inflated to conform to a blow mold; and (4) blow mold is opened and blown product is removed.
Blow molding is limited to thermoplastics. Polyethylene is the polymer most commonly used for blow molding; in particular, high density and high molecular weight polyethylene (HDPE and HMWPE). In comparing their properties with those of low density PE given the requirement for stiffness in the final product, it is more economical to use these more expensive materials because the container walls can be made thinner. Other blow moldings are made of polypropylene (PP), polyvinylchloride (PVC), and polyethylene terephthalate (PET).
The package finds utility to contain dairy and non-dairy milk products, usually liquids. Liquid should be understood to mean a liquid that is taken or derived from a protein source, such as coconut, soybean, cows, goats, etc. Non-dairy milk includes, for example, liquid derived from almonds, cashews, coconuts, flax, soy, rice, hazelnut, hemp, quino, etc.
Measuring Light Protection Performance or LPF
The LPF value quantifies the protection a packaging material can provide for a light sensitive entity in a product when the packaged product is exposed to light. The LPF value for a packaging material is quantified in our experiment as the time when half of the product light sensitive entity concentration has been degraded or otherwise undergone transformation in the controlled experimental light exposure conditions. Hence, a product comprising one or more light sensitive entities protected by a high LPF value package can be exposed to a larger dose of light before changes will occur to the light sensitive entity versus the product protected by a low LPF value package.
A detailed description of measuring LPF value is further described in commonly owned U.S. Pat. No. 9,638,679 titled, “Methods for Determining Photo Protective Materials” and U.S. Pat. No. 9,372,145 titled, “Devices for Determining Photo Protective Materials incorporated herein by reference. Additional information may be found in the Examples herein. The LPF values reported in the Examples that follow were measured according to the teachings of the above patent applications.
The current invention is focused on identifying new packages with light protective properties that protect species from photo chemical process (e.g., photo oxidation). Photochemical processes alter entities such as riboflavin, curcurim, myoglobin, chlorophyll (all forms), vitamin A, and erythrosine under the right conditions. Other photosensitive entities that may be used in the present invention include those found in foods, cosmetics, pharmaceuticals, biological materials such as proteins, enzymes, and chemical materials. In the present invention, LPF protection is reported for the light sensitive entity riboflavin. Riboflavin is the preferred entity to track performance for dairy applications although other light sensitive entities may also be protected from the effects of light.
Treated TiO2 particles comprising an inorganic surface modification using alumina hydrous oxide, fluoride ions and organosilicon compound were prepared substantially according to the teachings of U.S. Pat. No. 5,562,990.
Low density polyethylene (LDPE) (DuPont 20, DuPont, Wilmington, Del.) and TiO2 and color pigment masterbatch concentrate pellets were pre-weighed in amounts to yield the final ratios desired in batches of 190 g. Concentrate and resin mixtures were compounded on a two-roll mill (Stewart Bolling & Co., Cleveland, Ohio) at 220-240° F. with a gap of 0.035 in. The initial melt was performed with rollers stationary, and roller speed was slowly increased from 10 ft/min to final speeds of 45 and 35 ft/min for front and back rollers, respectively. Material was cut off the rollers, folded, and re-applied a total of 10 times to ensure complete mixing. The material was removed from the rollers for the final time as a single sheet and this stock was immediately cut into smaller pieces to better fit the compression mold. Compression molding of rigid plaques from this material was performed using two hydraulic presses (Carver, Wabash, Ind.) in sequence, the first heated to 350° F. to melt and mold the material and the second water-cooled to freeze the plaque shape. Compounded LDPE material was placed between Mylar sheets over a mold between platens, held for 2 min at a pressure of 25 tons in the hot press, and then for 2 min at 12.5 tons in the cold press. The Mylar was removed and excess plastic around each plaque was trimmed, yielding rectangular plaques about 5 cm by 10 cm with average thickness of approximately 30 mil. This procedure was repeated at different levels of masterbatch concentrates to produce the desired series of samples with varied composition.
As disclosed in commonly owned WO2016/196529, the light protection performance of a packaging material can be quantified with a light protection factor (“LPF”) value. Further, as disclosed in commonly owned U.S. Pat. No. 9,638,679, sample holders can be selected to hold different types of packaging samples.
The cap LPF measurements employed a specialized cap holder to study these smaller packaging parts, as shown in
To renormalize the LPFc numbers to the same scale as the standard square LPF evaluation sample holder used for the remaining evaluations of the bottle and wrap samples, a series of packages were evaluated in both sample holders to build a correlation between the LPF and LPFc data. This correlation was used to renormalize the measured LPFc numbers to the standard LPF scale. The resultant data from these experiments is captured in Table 1 and represents the average of at least two replicate evaluations.
A linear regression was performed on the data in Table 1 to a simple y=m×model with LPFc as y, LPF as x, and m as the fitted slope. An excellent correlation was observed with a correlation coefficient (R2) value of 0.9993 and a slope of 1.3355 is shown in
A series of liquid dairy food products in plastic packages were purchased from retail food stores. These food products selected as packages of interest as they were in packages with light protection features. These packages consisted of monolayer plastic bottles with additional layers in some samples including labels or wraps covering portions of the bottle surface, with plastic closures or caps. In this series of products, there were no additional layers under the cap (e.g., foils or seals). The packages are described below.
Applying the teachings of WO2016/196529, U.S. Pat. No. 9,372,145, and U.S. Pat. No. 9,63,679 and Example 1, this series of package samples was evaluated for their LPF values, or light protection performances, by measuring the performances of the individual package components including the bottle, the bottle plus wrap composite (where applicable), and cap. The bottle and bottle with wrap composite were measured for LPF as taught in the examples of U.S. Pat. No. 9,63,679. The caps were evaluated using the methods of the examples of U.S. Pat. No. 9,63,679 but also the cap holder described in Example 1 to yield the LPFc values and the data was normalized using the equation of Example 1 and reported on an LPF basis. All LPF data is reported in Table 2.
For a light protection package design of the claimed invention, an LPF of greater than 20 is needed for all the package components. As can be seen in the data table, the LPF value of packages varies substantially across the components.
Package 140 has components that are all less than LPF 12 and thus would not be suitable for the application.
Package 141 has a wrap that is LPF of greater than 100 and a bottle that is LPF150, but the LPF of the cap is only LPF 12 and thus the design is not of sufficient light protection performance due to the deficiencies of the cap.
Package 142 has a bottle with low light protection of LPF less than 1. The wrap offers improved performance but is not complete and leaves bottle areas exposed to light. The cap provides a high light protection performance with an LPF of greater than 100; however, this cap is not a monolayer as it has an insert under the top portion.
Through these examples we do not find a monolayer design of a bottle plus cap that is able to provide sufficient light protection of LPF 20 or greater. Further we did not find suitable design elements that could be combined across these packages to provide the solution claimed in the invention of the application.
A plastic package including a bottle and closure of the claimed invention were designed to contain liquid dairy product. The plastic package components including a bottle and cap were produced and evaluated using the methods of Example 1 and 2. This package consisted of a monolayer plastic bottle comprising polyethylene terephthalate (PETE or PET) with Ti-Pure™ TS-1601 Treated Titanium Dioxide and a monolayer plastic cap comprising high density polyethylene (HDPE) with Ti-Pure™ TS-1600 Treated Titanium Dioxide.
These packaging components were produced using standard package production processes known to those that are skilled in the art. The bottle was produced by injection stretch blow molding and the Ti-Pure™ titanium dioxide was added to the injection molding process as a masterbatch along with natural resin to produce the preform. The preform was then used to produce the bottle by stretch blow molding. The cap was produced by injection molding and the Ti-Pure™ titanium dioxide was added to the injection molding process as a masterbatch and added with natural resin.
The stretch blow molding process yielded a bottle with a wall thickness of 24.5 mil and a TS-1601 composition of 7.0 wt %. The cap was produced to a top portion thickness of 31.8 mil and a TS-1600 composition of 3.8 wt %. There were no additional layers under the cap (e.g., foils or seals). The bottle and cap were evaluated for their LPF performances. The LPF performance of the bottle was greater than LPF 100. The LPF performance on the cap was LPF 46.
The performance objective was to create a package with LPF above 40 and as both the bottle and cap tested higher for LPF than this threshold, the design criteria were achieved.
This example demonstrates the ability to measure and quantify the deficiency of current white caps on certain, representative retail dairy beverage packages.
Using the LPF measurement method disclosed in commonly owned U.S. Pat. No. 9,638,679, a modified sample holder (
Using the cap sample holder, white caps obtained from dairy beverage packages purchased at retail were measured for cap top portion light protection performance, LPFc. In addition, the caps were characterized for thickness in their top portion where each reported value represents an average of several measurements taken over the cap top portion in areas without features (e.g., raised symbols or codes impressed into the cap). The results are provided in Table 4, below.
The measured light protection factor of the caps is all below LPFc15, indicating a low light protection performance. Light protection performances of LPFc50 or higher are desired for this application to ensure preservation of the nutrient content in the packaged product. The top portion thicknesses of the caps are all below 46 mil. All of the caps evaluated were below the LPFc50 target indicating that light protection is insufficient and that light can enter the package through the cap top portion and cause detrimental effects to the nutrients and sensory quality (e.g., color, odor, flavor) of the packaged product.
This example illustrates how increasing the top portion thickness can result in increasing the cap LPFc and achieve the desire light protection performance in this part of a package design.
LPFc was measured as described in Comparative Example 1 on a set of white parts prepared to simulate a cap top portion. This set of samples demonstrates the impact on light protection performance of increasing top portion thickness on a cap. The white parts were produced by injection molding, the same processing typically used for cap production. The parts were composed of polyethylene and surface treated Ti-Pure™ TiO2 (TS-1600, available from the Chemours Company, Wilmington, Del.) at a loading of 1 wt % added to the cap using a 50 wt % Ti-Pure™ TS-1600 TiO2 masterbatch. It is noted that this level of TiO2 can be utilized in injection molding processes by one skilled in the art without difficulty. For this design an LPFc of greater than 100 was desired. The results of the measurements are provided in Table 5.
These data demonstrate that for a fixed composition of Ti-Pure™ TiO2 in polyethylene, by increasing the thickness of the material by about 3 times, the light protection performance is increased about 4.3 times. Thus, for a cap prepared with this same composition, increased light protection can be obtained with a thicker top cap portion.
For the design objective of achieving a LPFc of greater than 50, the thickness of the white step 3 sample provides the desired light protection performance. Further, the data in Table 5 can be modeled with an exponential function and with the model it is predicted that LPFc of 50 can be achieved with a thickness of 67.6 mil with this same composition.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2018/025372 | 3/30/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62479845 | Mar 2017 | US | |
| 62575728 | Oct 2017 | US |
