RU2729955C2 - Methods and compositions for direct printing with improved capacity for recycling - Google Patents

Abstract

FIELD: paint industry.

SUBSTANCE: invention relates to marking paint compositions for digital printing technology on the outer surface of a plastic article. Compositions of the marking paint contain an additive which promotes removal of the marking paint. In some aspects, the additive promoting removal of the marking paint can facilitate separation of the image from the outer surface of the article or loosening of adhesion to the outer surface of the article, when image is exposed to solution on liquid base at high temperature. Also described are recyclable plastic articles having an outer surface coated thereon, using described marking paint compositions, an image, and methods of removing hardened marking paint from plastic containers.

EFFECT: presented abstract is provided as a scanning tool for searching in a certain field of technology and is not intended to limit this invention.

53 cl, 6 tbl, 2 ex, 2 dwg

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority on the basis of US patent application No. 14/846032, filed September 4, 2015, which is a continuation of US patent application No. 14/528324, filed October 30, 2014, which is an integral part of the US patent application No. 13/168181, filed June 24, 2011, and now published as US patent No. 8876979, which claims priority based on provisional US patent application No. 61/360512, filed July 1, 2010, and further is a partial continuation of U.S. Patent Application No. 12/581952, filed October 28, 2009, which claims priority based on U.S. Provisional Patent Application No. 61/106860, filed October 20, 2008, all of the above applications are incorporated herein in full volume by reference.

FIELD OF TECHNOLOGY

The present invention generally relates to marking ink compositions for digital printing on the outer surfaces of plastic products. The present invention also relates to digital imprinted plastic products including digitally imaged plastic containers with improved adhesion and / or recycling properties, and methods that facilitate their recycling.

LEVEL OF TECHNOLOGY

In the plastics packaging industry, the trend of increasing volumes of recycling continues. Recently, container manufacturers have begun to produce digitally printed containers that are legible and of sufficient quality to compete and possibly replace prior conventional coding technologies. Examples of such printing technologies are described in common use US patent No. 7625059 and US patent No. 7,736,713, which are fully incorporated herein by reference.

Potential problems arise in situations where digitally printed containers are processed using conventional container recycling methods. Several problems have been mentioned and addressed in US patent application No. 12/581952, which is also incorporated herein by reference in its entirety. There is a clear trend towards improving and increasing efforts to recycle plastic containers between container manufacturers, brand owners, end users and government agencies. Therefore, it is desirable to provide industrially acceptable products that are sufficiently compatible with existing infrastructure and recycling processes, or that provide sufficient incentives and / or volumes to drive industry-wide change. At least initially, it would be desirable to provide digitally printed image products that are recyclable using standard industry standard processes, that is, processes that typically involve high temperature washing and milling. Thus, there is a need for digitally printed image plastic products, such as containers, which have digital images that adhere to the product without quality issues throughout its life, but are more easily removed during plastic recycling processes.

BRIEF DESCRIPTION OF THE INVENTION

In a typical aspect, a marking ink composition for digital printing on a plastic product is described. The marking ink composition typically contains a base marking ink, an additive that helps to remove the marking ink, and a carrier medium capable of dissolving at least a portion of the additive that helps to remove the marking ink. The removable additive is configured or selected to cause at least a portion of the cured drops of marking ink to detach from the outer surface or weaken the adhesion to the outer surface of the plastic article when the digitally printed image is exposed to a liquid solution (e.g. , water-based) at or near a predetermined elevated temperature. Such a predetermined elevated temperature may, without limitation, include temperatures associated with conventional recycling processes.

In another aspect, a recyclable plastic article is disclosed that has an outer surface with a digitally printed, cured ink droplet, image printed on it. The marking ink droplets contain a marking ink composition, as summarized above, which includes a stripping aid. Also described are embodiments of methods for removing said marking ink from plastic containers and methods for facilitating such recycling.

Additional advantages of the present invention will be set forth in part in the description that follows, in part will be apparent from this description, or may be learned by practice of the invention. The advantages of this invention will be realized and attained through the use of the elements and combinations pointed out in particular in the appended claims. It should be understood that the foregoing general description and the following detailed description are exemplary only and are provided for the purpose of explanation, and are not limiting of the invention as claimed.

BRIEF DESCRIPTION OF THE GRAPHIC MATERIALS

Hereinafter, by way of example only, with reference to the accompanying drawings, embodiments of the present invention will be described, wherein:

FIG. 1 generally illustrates a side view of a portion of a plastic container with an embodiment of a digitally printed image thereon;

FIG. 2 is a general representation of a quality overview table / matrix that can be used to evaluate the acceptability of a printed image on a plastic product.

DETAILED DESCRIPTION OF THE INVENTION

A detailed overview will now be made of typical embodiments of the present invention in various aspects, examples of which are described herein and illustrated in the accompanying drawings. While the invention will be described in relation to the listed embodiments, it should be understood that they are not intended to limit the invention to such embodiments. On the contrary, this invention is intended to cover all alternatives, modifications and equivalents that may be included within the spirit and scope of this invention as defined by the appended claims.

In a general context, but not limitation, a portion of the surface 10 of a plastic article (eg, a container) with an embodiment of a printed image 20 is generally illustrated in FIG. 1. The illustrated embodiment of image 20 includes a basecoat 30 , which may be composed of a plurality of basecoat ink droplets 32, and may also include a subcoat 40 , which may be a plurality of subcoat ink droplets 42 .

The packaging (which includes bottles) associated with the present invention is composed of a plastic deformable material or resin (e.g., acrylonitrile butadiene styrene (ABS), polyethylene terephthalate (PET), polystyrene (PS), polyethylene (PE) (which includes polyethylene high density (HDPE), polypropylene (PP), polyvinyl chloride (PVC), etc.) In addition, containers can be single-layer or multi-layer containers and can be formed using a variety of conventional molding techniques, including but not limited to injection molding , blow molding, thermoforming, etc. In one embodiment of the invention, the outermost layer / surface may be comprised of a plastic deformable material that has not been used. Although it should be noted that containers in accordance with the principles of the present invention may also include itself a certain percentage of recycled content, thus including a certain percentage of recycled content in outer layer of the container.

In embodiments of the invention, an article (eg, a container) may include a first coat or base coat (eg, base coat 30 shown in FIG. 1). The basecoat 30 may be composed of a plurality of basecoat ink drops 32 that are printed (eg, digitally printed, such as by a drop-at-the-time inkjet process) on the outer surface of the product and subsequently hardened, or which provide curing. The marking ink can be a UV curable marking ink that can be used in a variety of known ways, including, but not limited to, UV or light-emitting diode (LED) lamps. The ink droplets can be monomer-based and are composed of a marking ink composition that serves to improve the application of the ink droplets (eg, provide good printability) and / or provide a visual characteristic (eg, color or texture). For embodiments of the invention, basecoat 30 may contain white and / or colorless areas. In addition, with the described ink droplets, that is, those based on monomers, curing can lead to polymerization of the ink droplets. Since the marking inks used are not solvent-based inks, the marking ink can be formulated such that, during recycling processes, the marking ink does not ooze in solutions and does not release volatile components, which is possible with solvents. It is noted that the US Environmental Protection Agency (EPA) has issued recommendations for solvents, but polymers are solids and do not evaporate or emit volatiles. This means that the separation of the marking ink in the manner described in this document can be mechanical in nature, since the marking ink is in a cured polymer state and can be physically removed (for example, in the form of flakes or film) rather than entering composition as part of chemical decomposition.

As summarized above, the marking ink composition, which constitutes the marking ink droplets, includes a stripping aid. In some aspects, the "stripping aid" comprises at least one hydrophilic component or acidic component. Hydrophilic components can contain one or more composite elements that have hydrophilic (moisture-loving) properties. Acidic components can contain one or more composite elements that exhibit acidic properties. In some embodiments of the invention, the removal aid will comprise a combination of hydrophilic and acidic components, ie, at least two removal aid. For some ink droplet formulations, a “dual” formulation in which the removal aid contains both hydrophilic and acidic components, a lower percentage by weight (to total) may be used to provide results comparable to using a formulation with only one additive.

Such hydrophilic components can include hydrophilic monomers, hydrophilic oligomers, and water-dispersible monomers that provide the desired functionality. Hydrophilic monomers are often defined as monomers with oxygen or nitrogen atoms in addition to halogens in their backbone structure. Such monomers are usually susceptible to degradation by polar solvents such as water and ketones. Hydrophilic monomers are also less resistant to thermal degradation. Therefore, the inclusion of one or more hydrophilic components in the respective ink droplets can at a later point (eg, a point of recycling after use) improve the separation of the image (ie, cured ink droplets) from the plastic structure of the article. By way of example, but not limited to, in the cured state, the hydrophilic portion of the polymer typically absorbs water. When this happens, water can act as a plasticizer, increasing the mobility of the polymer chains. The increased mobility can soften the polymer, making it more susceptible to removal. Thus, exposing a plastic article, such as a container, containing an image containing a marking ink composition with an additive that helps to remove (for example, a hydrophilic monomer), a liquid-based solution (for example, actively stirred water) at an elevated temperature will help soften the composition marking ink (i.e., hydrophilic monomer) and separating the image from the plastic deformable material. The elevated temperature can be a predetermined temperature and can be a temperature that is higher than the temperature that the article normally encounters during normal use. In addition, where desired, a threshold for release of the adhesive bond can be set so that softening and subsequent removal essentially only occurs at elevated temperatures (e.g., during a recycling process) and is essentially not allowed under normal predefined use. It is noted that aliphatic urethane acrylates are a general class of hydrophilic monomers that typically absorb water and can potentially be used as a hydrophilic component. In addition, provided that they have the appropriate viscosity (ie, are not too viscous) for ink jet / digital printing applications, some hydrophilic oligomers can also be used as a hydrophilic component.

Without limitation, for some embodiments of the invention, the removal promoter may include hydrophilic monomers with a percentage by weight based on total weight (eg, associated marking ink and remover) ranging from about 0 to 20% by weight. In some embodiments, the percentage of the removal aid will range from about 0 to 10% of the total weight. Without limitation, an example of a hydrophilic monomer that can be used is methoxy polyethylene glycol monoacrylate (eg, CD 553, commercially available from Sartomer USA, LLC (Sartomer)).

It is noted that some water-dispersible monomers are also hydrophilic and tend to absorb water upon curing. With such a composition, the water can act as a plasticizer and soften the cured marking ink composition (eg, the cured film of the marking ink on the surface of the container), which facilitates the removal of the film of the marking ink during the recycling process. In embodiments of the present invention, the inclusion of a suitable hydrophilic component in the marking ink composition can add hydrophilic quality to the marking ink while maintaining inkjetability and adhesion of the marking ink to the substrate of the article throughout the life of the article.

Acidic components include acidic monomers, which have a measurable acidic value. It is noted that the measured value may be based on a pH value, a weight percent acid, or a titration value of an alkaline chemical (eg, mg KOH / g [milligrams of potassium hydroxide per gram of monomer]). In addition, for example, in the cured state, the acidic portion of the polymer may be exposed to an alkaline solution. The reaction between the acidic functionality of the polymer chain and the alkaline properties of the solution can result in decreased adhesion to the applied substrate, thereby facilitating polymer separation. Without limitation, examples of acid monomers that can be used include an acid acrylate oligomer (eg, CN 147, commercially available from Sartomer) and a monofunctional acid ester (eg, CD 9050, commercially available from Sartomer). For example, when a container containing an acidic component is contacted with a wash solution (eg, a conventional alkaline wash solution), interacting bonds can be broken, which aids in the desired separation of the printed image (ink droplets) from the plastic substrate.

In other aspects, the stripping aid is configured or otherwise selected according to its desired properties that can facilitate removal of the cured marking paint composition from the surface of the plastic article. For example, in one aspect, it is desirable for the removal aid to exhibit a relatively high solvent solubility and a relatively high water solubility, combined with a glass transition temperature that is lower than that typically used in conventional recycling processes. To this end, in typical aspects, the stripping aid has a glass transition temperature (Tg) that is less than about 130 ° C. Typical aspects may include removal aids that have a glass transition temperature (Tg) that is less than about 120 ° C, less than about 110 ° C, less than about 100 ° C, less than about 90 ° C, less less than about 80 ° C, less than about 70 ° C, less than about 60 ° C, or even less than about 50 ° C. In a further aspect, the descaling agent has a glass transition temperature (Tg) in the range of about 50 ° C to about 130 ° C. In yet another aspect, the descaling agent has a glass transition temperature (Tg) in the range of about 55 ° C to about 125 ° C, or about 65 ° C to about 105 ° C, or about 55 ° C to about 95 ° C. In yet another aspect, the paint stripper can have a glass transition temperature (Tg) in any range derived from any of the above typical values.

As will be appreciated by one of ordinary skill in the art, the desired level of solubility in water can be characterized as a function of, for example, the acid number of the removal aid. The acid number can be expressed as the titration value of the alkaline chemical (eg, mg KOH / g [milligrams of potassium hydroxide per gram of removal aid)]. In these aspects, the scavenger can exhibit an acid number in the range of about 100 mg KOH / g to about 250 mg KOH / g, which includes values: 110 mg KOH / g, 120 mg KOH / g, 130 mg KOH / g, 140 mg KOH / g, 150 mg KOH / g, 160 mg KOH / g, 170 mg KOH / g, 180 mg KOH / g, 190 mg KOH / g, 200 mg KOH / g, 210 mg KOH / g , 220 mg KOH / g, 230 mg KOH / g, and 240 mg KOH / g. In another aspect, the descaling agent has an acid number in the range of about 150 mg KOH / g to about 205 mg KOH / g, which includes 175 mg KOH / g, 185 mg KOH / g, and 195 mg KOH / g. In yet another aspect, the descaler can have an acid number in any range derived from any of the above typical values.

In additional aspects, the stripping aid can have a glass transition temperature (Tg) that is less than about 100 ° C and an acid number in the range of about 100 mg KOH / g to about 250 mg KOH / g. In yet another aspect, the paint stripper may exhibit a glass transition temperature (Tg) in the range of about 50 ° C to about 90 ° C, and an acid number in the range of about 150 mg KOH / g to about 205 mg KOH / g. ... In yet another aspect, the descaler can have a glass transition temperature (Tg) and acid number in any range derived from any of the above typical values.

By selecting a removal aid that exhibits the desired combination of water solubility and glass transition temperature, a curing ink can be provided that exhibits the desired adhesion, scratch resistance and solvent resistance while also facilitating the removal of the marking ink. as a method that precedes the recycling method. When exposed to an alkaline aqueous environment at temperatures above the Tg of the stripper, softening of the additive can result in a relatively cleaner peel of the cured layer of marking paint from the plastic surface to which it has been applied.

Such removal additives may be present in the marking ink compositions in an amount of from about 1 to about 20 weight percent of the marking ink composition. Additionally, specific examples may include amounts of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19 wt%. In a further aspect an additive that helps to remove the marking ink can be present in an amount from any range of amounts derived from any of the above typical values. For example, removal additives may be present in the marking ink compositions in an amount from about 5 to about 20 weight percent of the marking ink composition.

In a typical aspect, paint stripping additives that exhibit the above combination of water solubility and relatively low glass transition temperature include styrene maleic anhydride resins. In yet another aspect, the styrene-maleic anhydride resins can be a styrene-maleic anhydride copolymer. In yet another aspect, the styrene maleic anhydride is esterified styrene maleic anhydride. Typical, non-limiting, commercially available styrene-maleic anhydride resins that are useful as a removal aid are Cray Valley SMA®3840 and SMA®1440F resins available from Total.

In further aspects, the marking ink composition, which constitutes the marking ink droplets, also contains a carrier medium capable of solubilizing and dissolving at least a portion of the marking ink remover. The carrier medium can be monomer-based or solvent-based. Typical monomers that can be used as a carrier include the class of acrylic monomers. In a typical aspect, suitable acrylic monomers may include 1,3-butylene glycol diacrylate, 1,6-hexanediol diacrylate, 1,3-butylene glycol dimethacrylate, isobornyl acrylate, or isodecyl methacrylate, or a combination thereof. In some aspects, the acrylic monomer is selected from 1,3-butylene glycol diacrylate, 1,6-hexanediol diacrylate, and 1,3-butylene glycol dimethacrylate. As noted above, in aspects, the carrier medium capable of solubilizing the removal aid can be a solvent-based medium. Suitable solvents in some aspects can be aprotic solvents or water-based solvents. Specific, but not limiting, examples of suitable solvent-based carrier media include N-methyl-2-pyrrolidone (NMP) and acetone.

The carrier component may be present in the marking ink compositions in an amount of from about 1 to about 20 weight percent of the marking ink composition. Additionally, specific examples may include amounts of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19 wt%. In a further aspect the carrier medium can be present in an amount from any range of amounts derived from any of the above typical values. For example, the carrier medium can be present in the marking ink compositions in an amount of about 5 to about 15 weight percent of the marking ink composition.

The main coloring part of the marking ink composition can be any conventionally known curing marking ink, such as a conventional UV curing marking ink. The base ink may be present in the marking ink composition in an amount of about 50 to about 85% by weight of the marking ink composition, which includes typical weight percentages: 51, 52, 53, 54, 55, 56, 57, 58, 59 , 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, and 84 wt% In a further aspect, the base marking ink may be present in any range of amounts derived from any of the above typical values. For example, the base paint can be present in the paint compositions in an amount of about 65 to about 85% by weight of the paint composition.

One typical aspect described herein is a marking ink composition comprising: (a) about 65 to about 85 weight percent of a base marking ink; (b) from about 5 to about 20 wt.% an additive to help remove marking ink having a glass transition temperature of less than about 100 ° C; and (c) about 5 to about 15 weight percent of a carrier medium capable of dissolving at least a portion of the paint stripper additive. According to this exemplary aspect, the base marking ink may be a white UV curing base ink, the ink removal additive may be styrene maleic anhydride resin, and the carrier medium may be a solvent-based medium and may contain N-methyl. -2-pyrrolidone (NMP) or acetone or other suitable solvent.

As described herein, recyclable plastic articles are disclosed comprising an image digitally printed directly onto a curved outer surface that contains cured droplets of a marking ink composition as described hereinabove. In a further aspect, an exemplary recyclable plastic product includes a curved outer surface with an image digitally printed directly onto the curved outer surface, the image contains cured ink droplets, and the ink droplets comprise a composition including an additive that helps remove the ink. paint that has a glass transition temperature of less than about 100 ° C. In yet another aspect, the digitally printed image has an adhesion index of at least 6.0 and up to 9.0, and the release agent is configured to separate the cured ink droplets from the curved outer surface or weaken the adhesion to the curved outer surface in the case where the digitally printed image is exposed to a basic solution at an elevated temperature of at least about 70 ° C.

In a further aspect, the article includes a plastic container. In another aspect, the plastic container is a bottle. In yet another aspect, the plastic container is composed of one or more of the following materials: polyethylene, polyethylene terephthalate, high density polyethylene, and polypropylene.

In yet another aspect, the removable additive present in the marking ink composition is configured to separate the cured drops of marking ink from the curved outer surface or to weaken the adhesion to the curved outer surface when the digitally printed image is exposed to a liquid-based solution. such as an aqueous solution or a water-based solution at a predetermined elevated temperature. For example, cured ink droplets may detach from the curved outer surface of the article or impair adhesion when the digitally printed image is exposed to a basic solution with a pH of at least about 10, 11, 12, or 13 and an elevated temperature in the range of about 70 to 90 ° C. In a further aspect, the stock solution has a pH in the range of about 12 to 13. According to aspects, after exposure to the stock solution at an elevated temperature for a sufficient period of time, at least about 90 wt% of the cured ink droplets are separated from the curved outer surface of the article. In yet another further aspect, the digitally printed image comprises a basecoat including a plurality of cured basecoat marking ink droplets and an additional coating including a plurality of cured subcoat marking ink droplets, the additional coating is applied to at least a portion of the basecoat ...

By way of example, but not limiting the invention, an embodiment of a polyethylene terephthalate (PET) container that includes an applied UV curing ink with a removable additive blended was for marking paint removal testing. The blended removal aid of the test container comprised acid monomers of the type indicated above, ie, an acid acrylate oligomer and / or a monofunctional acid ester. The container could be treated with a washer solution having a pH of at least 9.0, which can help remove markings, as is generally known in the field of plastic container recycling, while the solution is heated to about 85 ° C. Various samples were treated under these conditions for 12 minutes and rated on a scale of 0 to 5 as follows:

0 - no improvement in removal compared to control

1 - there is minimal improvement, removal occurs only in some areas due to scraping with a metal object

2 - there is some improvement, the entire film can be removed by scraping with a metal object

3 - the cured film of marking paint is removed by scraping with a fingernail

4 - the cured film of marking paint can be easily removed simply by wiping with a clean cloth

5 - The cured film of the marking ink falls off during rinsing.

The testing was intended, among other things, to determine solutions that provide a removal efficiency level of 4 or 5. However, a level of at least 4 is not necessarily a requirement, and for some applications a lower removal level may also be acceptable. Test results have shown that the inclusion of stripper (acidic) additives blended with the marking paint formulation provides a significant improvement in the removal of cured marking paint from plastic (PET) material. Although both forms of acid additives showed improvement in ink removal with the current test configuration, a slightly lower compositional percentage of the acid acrylate oligomer as opposed to the monofunctional acid ester (10% versus 15%, respectively) was used to obtain at least level 4 on the offset scale.

In embodiments of the invention, the marking ink composition may optionally include a hydrophobic component. That is, the composition of the marking ink may, for example, include hydrophilic and hydrophobic components. Hydrophobic components can include hydrophobic (water repellent) monomers. Hydrophobic properties generally refer to polarity. The group of hydrophobic monomers is characterized by the presence of an organic backbone structure composed mainly of hydrogen and carbon, and thus such monomers tend to be non-polar and are resistant to polar solvents (such as water and alcohols) as well as acids and bases. For such two-component embodiments of the invention, the marking ink composition must balance hydrophilic and hydrophobic components (eg, hydrophilic monomers and hydrophobic monomers). Hydrophobic monomers can help keep ink droplets attached to the substrate of an article, while hydrophilic monomers can help soften (and even detach) when the image is exposed to a recycling / washing process (for example, in vigorously stirred water at elevated temperatures).

For an embodiment of a container with an image applied thereto, at least a first base coat 30 (which may include a hydrophilic component) may be applied to the surface of the container at a first time t ₁ and at a first temperature T ₁ . The temperature T ₁ will be in the range of temperatures that are suitable for the application of the bonded base coat. In one embodiment of the invention, basecoat 30 may have a cure capability (eg, ultraviolet (UV) radiation cure) and may further be cured prior to application of the additional coating.

In some embodiments, the subcoat 40 may be composed of a plurality of subcoat marking ink droplets 42 that are dispersed over at least a portion of the basecoat 30 . In addition, if desired, additional layers of "additional" coatings (eg, tertiary layer, etc.) can also be applied to the additional coating 40 . In embodiments of the present invention, the additional coating ink droplets 42 may also be comprised of a marking ink composition including a hydrophilic component.

The plurality of drops 42 of the overcoat marking ink may collectively form part of the application pattern, which in turn may form all or part of the image. In addition, as generally shown in FIG. 1, portions of one or more adjacent subcoat ink droplets 42 may overlap or mix with one another. The subcoat 40 and its constituent subcoat ink droplets 42 may comprise various known colors, including, but not limited to, primary print colors such as cyan, magenta, and yellow. In addition, controlling the blending or combination of specific colors in specific areas can provide additional "refined" colors. In addition, the overcoat ink droplets 42 may have a curing ability. For example, droplets of UV curable overcoat marking ink may contain all or part of the intended image. When curing is performed by exposure to radiation, the marking paint composition may include a photoinitiator. In addition, it is noted that the cured marking ink on the surface of the container can be mainly held by two bonds - that is, the polar bond between the polymer of the marking ink and the plastic, and the mechanical bond resulting from the surface of the plastic having an uneven surface at the microscopic level (for example , microstructure). For a number of embodiments of the present invention, both linkages are best used. For some applications, the hydrophilic component may work better on mechanical bonds, while the acid component may work better on polar bonds. Depending on the application, the overcoat ink droplets can vary in diameter, which can range, for example, from about 10 microns to about 200 microns. The additional coating 40 can be applied to the surface 10 of the container at a second time t ₂ and at a second temperature T ₂ , the second temperature T ₂ at which the additional coating 40 is applied is usually less than the first temperature T ₁ at which the base is applied. cover 30 .

In embodiments of the present invention, the time between basecoat application and additional coating application (eg, t ₂ minus t ₁ ) may be reduced — for example, to ten seconds or less. For some embodiments of the invention, the difference in application time will be between two and six seconds. In addition, in embodiments of the invention, the temperature difference between the temperature at which the basecoat 30 is applied and the temperature at which the subcoat 40 is applied to a portion of the basecoat 30 , i.e., T ₁ minus T ₂ , can be adjusted to be equal to or less than about 10 ° F. In some embodiments, the application temperature difference is from about 5 ° F to about 10 ° F. In addition, for some applications, it may be desirable to vary the temperatures associated with the application of base coat 30 and subcoat 40 so that the respective application temperatures are closer together - i.e., the temperature difference between the applied coatings is reduced or reduced to minimum. This can be achieved, for example, by (a) decreasing / decreasing T ₁ , (b) increasing / increasing T2, or (c) a combination of (a) and (b). Such aforementioned time and / or temperature control with respect to base coat and sub coat application can provide better adhesion of the resulting applied image to a given article.

It is noted that in addition to time and temperature, a factor that can also affect the effective cure rate for an applied image is the surface flux density. That is, specific points in time (for example, t ₁ and t ₂ ) and temperatures (for example, T ₁ and T ₂ ) can be associated with the surface radiation flux density - i.e. ε ₁ and ε ₂ . For example, in embodiments of the invention, the basecoat may be cured at an areal flux density ε _l , and the associated subcoat can be cured at an areal flux density ε ₂ . In addition, in embodiments of the invention, the effective cure rate, which can be based on a combination of time, temperature, and surface flux density, can generally be provided by the following equation:

Surface radiation flux density (ε) = ( dΦ / dA )

in this case, Φ = radiation flux (measured in watts), and A = area ( cm ² )

For example, without limitation, the range of surface flux density for some embodiments of the invention will be from about 0.1 W / cm ² to about 10.0 W / cm ² .

For some applications, such as when a curing ink is used (e.g. UV curing ink or radiation curing ink), the corresponding coating or marking ink can be cured after each respective imaging station. ... For example, without limitation, an embodiment of a method may at least partially include: applying a base coat; curing stage; additional coating and curing step. Alternatively, and also by way of example, but not limiting the invention, the method may at least partially include: a base coat, a cure step, a base coat, a cure step, an overcoat step, and a cure step.

In addition, for embodiments of the present invention, it may be desirable that the production / post-processing speed of containers / bottles matches or substantially matches the flow / processing speed of the respective printing machine (s).

In addition, it has been found that the quality of the printed images can be at least partially controlled and / or improved using one or more of the following technologies:

(a) selection and / or calibration of ink sets;

(b) temperature control of the substrate (ie the surface of the container); and / or

(c) time management.

With regard to the selection and / or calibration of the marking ink sets, they are performed at least in part by the selection and / or calibration of the marking ink containing the base and additional coatings. It has been found that the marking inks used can be selected to provide the desired temporal and / or temperature characteristics, including in relation to each other in combination. For example, the selection of certain marking inks with a given viscosity can exhibit or provide certain desired temperature effects.

With regard to temperature control of the substrate (i.e. the surface of the container), the corresponding part of the side wall (or other part of the container) can be heated to a certain temperature or controlled to some extent. For example, this part of the container can be pre-processed. Such pre-treatment can be facilitated using various known techniques, which may include, but are not limited to, flame treatment, corona treatment, and plasma treatment. However, the present invention is not limited to these specific pre-treatment technologies.

With regard to time management, it is possible to control the time associated with the movement of the container, for example, through the production machine, as well as the time for applying the base coat and / or additional coat. It may be desirable that the production / post-processing speed of the containers / bottles matches or substantially matches the flow / processing speed of the respective printing machine (s).

The present invention may also include a system for determining or evaluating "acceptability", such as the commercial acceptability of a container having an imprinted image, such as a digitally printed marking. That is, for embodiments of the present invention, the system for determining or evaluating may provide an “adhesion rating”. FIG. 2 is a general representation of a quality assessment table / matrix that can be used to determine or evaluate the acceptability of a printed container image. As shown generally, the y-axis can contain numbers associated with the overall pass / fail rating. In the illustrated embodiment, the numbers from 1 to 5 indicate that the container is not acceptable, and the numbers from 6 to 9 indicate that the corresponding container is acceptable. It is important to note that although a score of at least 6 would indicate pass as an acceptable value relative to the current table / matrix, the present invention is not limited to the specific table / matrix shown, and alternatively more pass ratings and / or the passing score can be raised or lowered as desired or necessary. The set of tests, which may include various standard tests, including those previously noted, are presented in columns arranged on the X-axis. For example, without limitation, Test 1 may include a "Sutherland Rub Test", Test 2 may contain a "Test 3M # 610 Tape Test ”, Test 3 may include a Delivery Simulation Test, and Test 4 may contain a“ 3M # 810 Tape Test ”. As generally shown in the table, various pass / fail designations may be presented in the table in relation to each Test selected. For some of the aforementioned "standard" tests, the tests may be modified as appropriate for use in connection with the applied image, as opposed to traditionally applied markings. For example, in various adhesive tape tests that may follow ASTM D 3359-08 standards, the table / matrix tests may or may not involve cutting off a portion of the image with a cutting tool prior to applying pressure sensitive adhesive tape. That is, in one embodiment, "Test 2" may include a "modified"# 610 3M Tape Test, since the portion of the container image that is being tested will not be cross-cut or otherwise separated from the container. In addition, in the table shown in FIG. 2, the indication “passed” with respect to tape tests directly using the modified ASTM standard (ie, the test does not include cross-cutting / severing) will typically represent any portions removed that do not exceed 2.0 mm ² . For tape tests directly applying the ASTM standard, the indication "passed" is usually a "4B" or "5B" classification (according to Fig. 1 - Classification of adhesion test results - ASTM), or less than 5% will be removed applied area.

In one embodiment, it is desirable to provide an imaged (eg, digitally printed image) container that at least passes the modified 3M # 610 Tape Test and is nonetheless “recyclable”. An image that is digitally printed on a container is considered “recyclable” if it reaches a classification value less than “4B” (ie 5% or more of the area removed) using ASTM D 3359 Adhesive Test tape No. 810. A digitally printed container that passes Test 2 (modified 3M Adhesive Tape Test # 610) and Test 3 (Simulated Delivery Test ") but still fails Test 4 (3M Adhesive Tape Test # 810) reaches the adhesion index is either 6.0 or 7.0. Such an overprinted container having an Adhesion Index of 6.0 or 7.0 is commercially suitable for shipping (i.e., passes the Delivery Simulation Test) while providing adhesion associated with the overlay that is sufficient for normal / intended use. but separates favorably for subsequent recycling. In other words, the adhesion associated with the digitally printed image is strong enough for the intended use, but does not prevent separation during recycling.

With regard to such a table / matrix, each test can be performed on an appropriate (eg statistically significant or representative) sample of containers. After all tests are completed, the results can be tabulated and entered into a table / matrix to provide an assessment of "adhesion". The corresponding assessment results can be correlated.

Among other things, the principles of this disclosure can provide improved recyclability. Efficient recycling of marking ink applied to a variety of products can provide a range of cost and efficiency benefits as well as environmental benefits. For example, without limitation, cans with digitally printed images (which may be formed by a UV-curable marking ink or a radiation-curable marking ink) that contain, at least in part, a marking ink composition comprising itself a hydrophilic and / or acidic component can be conveniently withdrawn from circulation compared to traditional plastic processing methods. The industry standard method for recycling plastic containers typically involves grinding the container into granular plastic flakes, exposing the flakes to a high temperature alkaline washing solution, drying the cleaned flakes, grading and extruding into resin pellets for resale. In embodiments of the invention that embody aspects of the described principles, the digitally printed image on the container may remain with the resin flakes after the grinding process, the digitally printed image will be substantially separated from the resin flakes during the high temperature alkaline washing process that can be vigorously mixed, and thus not contaminate the clean resin flakes to be formed into resin granules.

When using peel-off technologies, there are at least four methodologies that can be used - alone or in various combinations - to use polar and / or mechanical bonds to help remove marking ink from the surface of an article. Technologies include those that use: (1) water-based or liquid-based solutions (for example, for additives with hydrophilic components or those that have the desired Tg values and acid numbers, as described herein), (2) alkaline solution components (for example, for additives with acidic components or the desired combination of Tg and acid number, as described herein); i.e., chemical reactions can be used to release polar bonds, (3) heat or temperature, and / or (4) mechanical force (eg high pressure jet (psi, psi, 1 psi = 6894,757 Pa)), or any combination thereof.

This invention provides a number of recycling methods that can be used to remove marking ink from an article. For example, one embodiment of a method for processing a plastic container includes: providing a digitally printed plastic container, a marking ink composition including an additive that helps remove (e.g., a hydrophilic or acidic component), and digitally printed images of a liquid-based solution - for example, water with or without alkaline solution components - at elevated temperatures; stirring of the solution is optional. Before or after exposure, the container can undergo a grinding operation. Similar embodiments of the invention can be said to function in a manner that includes dry milling, washing, washing, drying and washing.

Another method, which may be more similar to conventional industrial recycling and is commercially available (for example from SOREMA (Italy)), can be said to include a single rinse, wet grinding, centrifugation, sorting, and a float tank / branch. For example, a "single rinse" can be used by feeding bottles (eg, with a control screw or multi-screw system) through a high pressure rinse (eg, high temperature alkaline rinse). This can add a mechanical force component to facilitate the removal of the mark. As a rule, the bottles are intact, that is, they do not wrinkle before such rinsing. Materials, including polymerized marking ink, can be washed off and placed in a collection system or grid system located below the transport mechanism.

In a further aspect, this invention relates to a method of removing cured marking ink from a plastic container, the method comprises: (a) providing a plastic container that has a curved outer surface digitally printed directly onto the curved outer surface of a plastic container using the method inkjet printing "drop at the right point at the right time", the image contains cured drops of marking ink applied directly to the curved outer surface of the plastic container and having an adhesion rating of at least 6.0 and up to about 9.0, and a drop of marking the paints contain a composition comprising a paint stripper having a glass transition temperature of less than about 100 ° C; (b) processing at least part of the digitally printed image of a plastic container with a base solution at an elevated temperature of at least about 70 ° C; and (c) removing at least part of the digitally printed image from the curved outer surface to which it was applied picture.

In a further aspect, the plastic container is a bottle. In yet another aspect, the plastic container is composed of one or more of the following materials: polyethylene, polyethylene terephthalate, high density polyethylene, and polypropylene.

In a further aspect, the paint remover comprises a styrene-maleic anhydride copolymer. In yet another aspect, the paint stripper has a glass transition temperature (Tg) in the range of about 50 ° C to about 130 ° C. In yet another aspect, the paint stripper has a glass transition temperature (Tg) in the range of about 65 ° C to about 110 ° C. In yet another aspect, the descaling agent has a glass transition temperature (Tg) in the range of about 55 ° C to about 65 ° C. In yet another aspect, the descaler has an acid number in the range of about 150 mg KOH / g to about 205 mg KOH / g. In yet another aspect, the descaler has an acid number in the range of about 165 mg KOH / g to about 205 mg KOH / g.

In a further aspect, the stock solution is an aqueous solution having a pH in the range of about 12-13 and with an elevated temperature in the range of about 70 to 90 ° C. In another aspect, the step of removing includes scraping or wiping off the marking ink from the container after processing the image with the base solution. In yet another aspect, the marking ink is mechanically removed in the form of flakes or film.

The above descriptions of specific embodiments of the present invention have been presented for illustrative and descriptive purposes. The present description is not intended to be exhaustive or to limit the invention to the precise forms described, and various modifications and variations are possible in light of the above principles. Embodiments of the invention have been selected and described to explain the principles of the invention and its practical application, thereby enabling others skilled in the art to use the invention and various embodiments of the invention with various modifications that are suitable for a particular use. It is intended that the scope of this invention be defined by the claims appended to this document and their equivalents.

EXPERIMENTAL PART

The following examples are provided to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices, and / or methods disclosed herein are prepared and evaluated, and are intended only for illustrative description, and not to limit this inventions. Efforts have been made to ensure accuracy with respect to numbers (eg, quantity, temperature, etc.), but some uncertainties and variations should be considered. Unless otherwise indicated, proportions are parts by weight, temperature is in ° C or room temperature, and pressure is atmospheric or near atmospheric.

In the following exemplary examples, various marking ink compositions in accordance with the present invention were prepared and tested for use in direct printing onto the outside of a plastic article. Marking ink compositions can be prepared by first dissolving the descaling agent in a carrier medium and then adding the carrier medium solution to the base marking paint. The resulting marking ink composition can then be used by direct printing onto the outer surface of a plastic article.

The performance and recyclability of various formulations of marking paint on plastic products were also evaluated. Marking ink compositions, including UV curing ink with a scavenger and carrier medium, were printed directly onto the surface of polyethylene terephthalate (PET), polyethylene (PE) and / or high density polyethylene samples (HDPE) and cured.

The cured sample ink was then subjected to a marking ink removal test, which could include testing one or more of adhesion, scratch resistance, and solvent resistance. Samples can be treated with a variety of washer solutions that can facilitate removal of markings, as is commonly known in the plastic packaging industry, such as a washer solution having a pH of at least 9.0 and heating the solution to about 75 ° C or 85 ° C. Testing was performed over time periods including time immediately after treatment (immediately) and 1 hour (1 hour) after treatment.

The materials presented in Table 1 were used to obtain the compositions described and evaluated herein.

Table 1

Name Description Provider Luwax S Montanic acid paraffin BASF Luwax V Polyester paraffin BASF Joncryl 538A Acrylic emulsion BASF Joncryl 611 Acrylic resin BASF Joncryl 682 Acrylic resin BASF Michem Flex R 1924 Water-based primer for printing Michelman, Inc BYK111 Acid copolymer additive Altana CITRIC Acid Lemon acid Sigma Aldrich DURACOTE Cold end coating Sun Chemical Ceraflour 998 PTFE-modified low molecular weight polyethylene Altana SMA1440 styrene-maleic anhydride copolymer Cray Valley USA, LLC SMA3840 styrene-maleic anhydride copolymer Cray Valley USA, LLC NMP N-methyl-2-pyrrolidone Sigma Aldrich

1. EXAMPLE 1.

In the following example, paraffins and resins were the additives to aid in the removal of the test samples. The carrier medium was acetone or N-methyl-2-pyrrolidone (NMP) (commercially available from Sigma Aldrich). The inventive marking ink formulations and performance data are shown in Tables 2-5 below. For the following data, “passed successfully” means that no removal of the marking ink was observed, and “failed” indicates that significant and / or complete removal of the marking ink was observed. Any of the listed% values correspond to the observed% paint removal.

table 2

immediately 1 h 1 h soaking in flowing water Composition Alkaline test score scraping adhesive tape 610 adhesive tape 810 scraping scraping adhesive tape 610 Luwax S (A) NOT APPLICABLE ended in failure ended in failure * ended in failure * ended in failure ended in failure ended in failure Luwax S (B) NOT APPLICABLE ended in failure ended in failure * ended in failure * ended in failure ended in failure ended in failure Luwax V (A) NOT APPLICABLE ended in failure ended in failure * ended in failure * ended in failure ended in failure ended in failure Luwax V (B) NOT APPLICABLE ended in failure ended in failure * ended in failure * ended in failure ended in failure ended in failure Joncryl 538A (A) NOT APPLICABLE was successful was successful ended in failure ended in failure was successful ended in failure Joncryl 538A (B) NOT APPLICABLE was successful was successful ended in failure ended in failure was successful 20% failed Joncryl 611 (A) NOT APPLICABLE ended in failure was successful 50% failed ended in failure was successful 40% failed Joncryl 611 (B) NOT APPLICABLE ended in failure was successful 50% failed was successful ended in failure ended in failure Joncryl 682 (A) NOT APPLICABLE was successful was successful 70% failed ended in failure ended in failure ended in failure Joncryl 682 (B) NOT APPLICABLE ended in failure was successful 70% failed ended in failure was successful ended in failure Michem (A) NOT APPLICABLE was successful was successful was successful ended in failure was successful was successful Michem (B) NOT APPLICABLE was successful was successful was successful ended in failure was successful was successful Control 0 ended in failure ended in failure ended in failure ended in failure ended in failure ended in failure Luwax S (A) NOT APPLICABLE ended in failure ended in failure ended in failure ended in failure ended in failure 50% failed Luwax V (A) 3 ended in failure ended in failure ended in failure ended in failure ended in failure ended in failure Luwax V (B) 3 insignificantly 50% failed ended in failure ended in failure ended in failure ended in failure Joncryl 538A (A) 1 insignificantly was successful ended in failure ended in failure was successful ended in failure Joncryl 538A (B) NOT APPLICABLE insignificantly was successful was successful ended in failure was successful ended in failure Joncryl 611 (A) 1 insignificantly was successful was successful ended in failure was successful ended in failure Joncryl 611 (B) 1 ended in failure was successful was successful ended in failure 50% failed ended in failure Joncryl 682 (A) 1 insignificantly was successful ended in failure ended in failure ended in failure ended in failure Joncryl 682 (B) 2 was successful was successful 50% failed ended in failure was successful ended in failure Michem (A) 0 was successful was successful was successful ended in failure was successful was successful Michem (B) 0 was successful was successful was successful ended in failure was successful was successful Control (A) 0 insignificantly was successful 50% failed was successful was successful ended in failure Control (B) 0 insignificantly was successful 50% failed ended in failure 50% failed ended in failure

failed * = failed partly due to insufficient adhesive tape adhesion to the surface; marking ink can be easily removed

Table 2. (continued)

immediately 1 h 1 h immediately 1 h immediately immediately 1 h immediately soaking in chilled water soaking in water 75C soaking in alkaline solution 75C Composition scraping scraping adhesive tape 610 scraping scraping adhesive tape 610 scraping scraping adhesive tape 610 Luwax S (A) ended in failure ended in failure ended in failure ended in failure ended in failure partially failed NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Luwax S (B) ended in failure ended in failure ended in failure ended in failure ended in failure partially failed NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Luwax V (A) ended in failure ended in failure ended in failure ended in failure ended in failure partially failed NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Luwax V (B) ended in failure ended in failure ended in failure ended in failure ended in failure partially failed NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Joncryl 538A (A) was successful was successful 50% failed ended in failure ended in failure ended in failure NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Joncryl 538A (B) was successful was successful 50% failed ended in failure was successful ended in failure NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Joncryl 611 (A) ended in failure ended in failure 30% failed ended in failure ended in failure 60% failed NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Joncryl 611 (B) ended in failure ended in failure 50% failed ended in failure was successful 40% failed NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Joncryl 682 (A) was successful was successful was successful was successful ended in failure ended in failure NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Joncryl 682 (B) was successful was successful 30% failed ended in failure ended in failure ended in failure NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Michem (A) was successful was successful was successful was successful was successful 30% failed NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Michem (B) was successful was successful was successful was successful was successful was successful NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Control ended in failure ended in failure ended in failure ended in failure ended in failure ended in failure NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Luwax S (A) ended in failure ended in failure ended in failure ended in failure ended in failure ended in failure NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Luwax V (A) ended in failure ended in failure ended in failure ended in failure ended in failure 20% failed ended in failure ended in failure ended in failure Luwax V (B) was successful failed slightly ended in failure ended in failure failed slightly ended in failure ended in failure ended in failure ended in failure Joncryl 538A (A) ended in failure was successful 50% failed ended in failure ended in failure ended in failure ended in failure insignificantly ended in failure Joncryl 538A (B) was successful was successful 50% failed ended in failure ended in failure ended in failure NOT APPLICABLE NOT APPLICABLE NOT APPLICABLE Joncryl 611 (A) was successful was successful was successful ended in failure ended in failure ended in failure insignificantly ended in failure ended in failure Joncryl 611 (B) ended in failure was successful was successful ended in failure was successful ended in failure insignificantly ended in failure ended in failure Joncryl 682 (A) was successful failed slightly 20% failed ended in failure ended in failure ended in failure ended in failure insignificantly ended in failure Joncryl 682 (B) ended in failure failed slightly ended in failure failed slightly failed slightly ended in failure ended in failure insignificantly ended in failure Michem (A) was successful was successful was successful failed slightly was successful 10% failed ended in failure was successful was successful Michem (B) was successful was successful was successful was successful was successful was successful ended in failure was successful was successful Control (A) was successful was successful 50% failed was successful was successful ended in failure insignificantly insignificantly 50% Control (B) was successful was successful 50% failed was successful was successful ended in failure insignificantly insignificantly ended in failure

Table 3

immediately 1 h 1 h soaking in flowing water Composition Alkaline test score scraping adhesive tape 610 adhesive tape 810 scraping scraping adhesive tape 610 BYK111 + J 682 (A) 1 was successful was successful ten% ended in failure ended in failure ended in failure BYK111 + J 682 (B) 1 ended in failure was successful 50% ended in failure ended in failure ended in failure BYK111 + J 682 (C) 2 ended in failure was successful 20% ended in failure ended in failure ended in failure CITRIC + J 682 (A) 2 ended in failure was successful one hundred% ended in failure ended in failure ended in failure CITRIC + J 682 (B) 1 ended in failure was successful 60% ended in failure ended in failure ended in failure CITRIC + J 682 (C) 1 ended in failure ended in failure 20% ended in failure was successful ended in failure BYK111 + J538A (A) 1 was successful was successful 20% ended in failure was successful ended in failure BYK111 + J538A (B) 2 was successful was successful 20% ended in failure insignificantly ended in failure BYK111 + J538A (C) 1 was successful was successful one hundred% ended in failure insignificantly ended in failure CITRIC + J538A (A) 0 was successful was successful 60% ended in failure insignificantly ended in failure CITRIC + J538A (B) 0 was successful was successful 20% ended in failure ended in failure ended in failure CITRIC + J538A (C) 1 was successful was successful was successful moderately was successful ended in failure BYK111 + DURACOTE (A) 1 insignificantly was successful was successful ended in failure ended in failure ended in failure BYK111 + DURACOTE (B) 2 insignificantly was successful was successful ended in failure ended in failure ended in failure BYK111 + DURACOTE (C) 1 insignificantly was successful was successful ended in failure ended in failure ended in failure CITRIC + DURACOTE (A) 0 insignificantly was successful 20% was successful was successful ended in failure CITRIC + DURACOTE (B) 0 insignificantly was successful was successful insignificantly was successful ended in failure CITRIC + DURACOTE (C) 0 insignificantly was successful was successful moderately insignificantly ended in failure BYK111 + MICHEM (A) 1 insignificantly was successful 50% ended in failure was successful was successful BYK111 + MICHEM (B) 1 was successful was successful was successful ended in failure was successful was successful BYK111 + MICHEM (C) 1 insignificantly was successful was successful ended in failure was successful 20% CONTROL (A) 0 insignificantly was successful was successful insignificantly was successful ended in failure CONTROL (B) 0 insignificantly was successful was successful insignificantly insignificantly ended in failure

Table 3. (continued)

immediately 1 h 1 h immediately 1 h immediately soaking in chilled water soaking in alkaline solution 75C Composition scraping scraping adhesive tape 610 scraping scraping adhesive tape 610 BYK111 + J 682 (A) ended in failure ended in failure was successful ended in failure ended in failure ended in failure BYK111 + J 682 (B) ended in failure insignificantly was successful ended in failure ended in failure ended in failure BYK111 + J 682 (C) ended in failure insignificantly was successful ended in failure ended in failure ended in failure CITRIC + J 682 (A) ended in failure insignificantly ended in failure ended in failure ended in failure ended in failure CITRIC + J 682 (B) ended in failure insignificantly was successful ended in failure ended in failure ended in failure CITRIC + J 682 (C) ended in failure ended in failure was successful ended in failure ended in failure ended in failure BYK111 + J538A (A) ended in failure was successful ended in failure ended in failure ended in failure ended in failure BYK111 + J538A (B) ended in failure was successful ended in failure ended in failure ended in failure ended in failure BYK111 + J538A (C) ended in failure insignificantly ended in failure ended in failure ended in failure ended in failure CITRIC + J538A (A) ended in failure ended in failure ended in failure ended in failure insignificantly ended in failure CITRIC + J538A (B) ended in failure was successful ended in failure ended in failure insignificantly ended in failure CITRIC + J538A (C) ended in failure was successful was successful ended in failure ended in failure ended in failure BYK111 + DURACOTE (A) ended in failure ended in failure was successful ended in failure ended in failure ended in failure BYK111 + DURACOTE (B) ended in failure ended in failure ended in failure ended in failure ended in failure ended in failure BYK111 + DURACOTE (C) ended in failure ended in failure 50% ended in failure insignificantly ended in failure CITRIC + DURACOTE (A) was successful insignificantly ended in failure insignificantly insignificantly ended in failure CITRIC + DURACOTE (B) was successful insignificantly ended in failure insignificantly insignificantly ended in failure CITRIC + DURACOTE (C) was successful insignificantly ended in failure insignificantly insignificantly ended in failure BYK111 + MICHEM (A) was successful was successful was successful was successful insignificantly 50% BYK111 + MICHEM (B) was successful insignificantly was successful was successful insignificantly 50% BYK111 + MICHEM (C) was successful was successful was successful insignificantly insignificantly ended in failure CONTROL (A) was successful was successful ended in failure was successful insignificantly ended in failure CONTROL (B) was successful was successful was successful insignificantly insignificantly ended in failure

Table 4

immediately 1 h 1 h soaking in flowing water Composition Alkaline test score scraping adhesive tape 610 adhesive tape 810 scraping scraping adhesive tape 610 Ceraflour 998 (A) 0 was successful was successful was successful was successful was successful was successful Ceraflour 998 (B) 1 was successful was successful was successful was successful was successful was successful SMA1440 (50% solids) (A) 4 was successful 50% ended in failure was successful was successful was successful SMA1440 (50% solids) (B) five was successful was successful 50% was successful was successful 50% SMA1440 (50% solids) (C) 4 was successful was successful ended in failure was successful was successful 50% SMA1440, 50% (25% solids) (A) 4 was successful was successful was successful was successful was successful was successful SMA1440 50% (25% solids) (B) 3 was successful was successful was successful was successful was successful 50% SMA1440, 50% (25% solids) (C) 4 was successful was successful was successful was successful was successful 50% SMA3840 (A) 2 was successful was successful was successful was successful was successful was successful SMA3840 (B) 2 was successful was successful was successful was successful was successful was successful SMA3840 (C) 1 was successful was successful was successful was successful was successful was successful J682, 50% (A) 0 was successful was successful was successful was successful was successful was successful J682, 50% (B) 1 was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 / 1% 998 (A) 4 was successful was successful was successful was successful was successful was successful SMA1440 / 1% 998 (B) 4 was successful was successful was successful was successful was successful was successful SMA1440 / 1% 998 (C) 4 was successful was successful was successful ended in failure was successful was successful Control (A) 0 was successful was successful insignificantly was successful was successful was successful Control (B) 0 was successful was successful was successful was successful was successful was successful

Table 4. (continued)

immediately 1 h 1 h immediately 1 h 1 h soaking in chilled water soaking in alkaline solution 75C Composition scraping scraping adhesive tape 610 scraping scraping adhesive tape 610 Ceraflour 998 (A) was successful was successful was successful was successful was successful was successful Ceraflour 998 (B) was successful was successful was successful was successful was successful was successful SMA1440 (50% solids) (A) was successful was successful ten% ended in failure ended in failure ended in failure SMA1440 (50% solids) (B) was successful was successful ended in failure ended in failure ended in failure ended in failure SMA1440 (50% solids) (C) was successful was successful ended in failure ended in failure ended in failure ended in failure SMA1440, 50% (25% solids) (A) was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 50% (25% solids) (B) was successful ended in failure was successful ended in failure ended in failure ended in failure SMA1440, 50% (25% solids) (C) was successful was successful was successful ended in failure ended in failure ended in failure SMA3840 (A) was successful was successful was successful was successful was successful 50% SMA3840 (B) was successful was successful was successful was successful was successful 20% SMA3840 (C) was successful was successful was successful was successful was successful was successful J682, 50% (A) was successful was successful was successful was successful was successful was successful J682, 50% (B) ended in failure was successful was successful ended in failure ended in failure ended in failure SMA1440 / 1% 998 (A) was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 / 1% 998 (B) was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 / 1% 998 (C) was successful was successful ended in failure ended in failure ended in failure ended in failure Control (A) was successful was successful was successful was successful was successful was successful Control (B) was successful was successful was successful was successful was successful was successful

Table 5

immediately 1 h 1 h soaking in flowing water Composition Alkaline test score scraping adhesive tape 610 adhesive tape 810 scraping scraping adhesive tape 610 Control A 0 was successful ended in failure ended in failure was successful was successful ended in failure Control B 0 was successful ended in failure ended in failure was successful was successful ended in failure Control C 0 was successful ended in failure ended in failure was successful was successful ended in failure Control D 0 was successful was successful ended in failure was successful was successful ended in failure Control E 0 was successful was successful was successful was successful was successful ended in failure Control F 0 was successful was successful ended in failure was successful was successful was successful SMA1440 (in acetone) as primer A 2 was successful was successful was successful was successful was successful was successful SMA1440 (in acetone) as primer B 3 was successful was successful was successful was successful was successful was successful SMA1440 (in acetone) as primer C 3 was successful was successful was successful was successful was successful was successful SMA1440 (in acetone) as primer D 4 was successful was successful was successful was successful was successful was successful SMA1440 (in acetone) as E primer 4 was successful was successful was successful was successful was successful was successful SMA1440 (in acetone) as primer coat F 3 was successful was successful was successful was successful was successful was successful SMA1440 (in acetone) as primer A five was successful was successful was successful was successful was successful was successful SMA1440 (in acetone) as primer B five was successful was successful was successful was successful was successful was successful SMA1440 (in acetone) as primer C 4 was successful was successful was successful was successful was successful ended in failure SMA1440 (in acetone) as primer D 4 was successful was successful was successful was successful was successful was successful SMA1440 (in acetone) as E primer five was successful was successful was successful was successful was successful was successful SMA1440 (in acetone) as primer coat F five was successful was successful was successful was successful was successful ended in failure SMA1440 (and 10% acetone) in marking ink A five was successful was successful was successful was successful was successful was successful SMA1440 (and 10% acetone) in marking ink B 4 was successful was successful was successful was successful was successful was successful SMA1440 (and 10% acetone) in marking ink C 3 was successful was successful ended in failure was successful was successful was successful SMA1440 (and 10% acetone) in marking ink D 4 was successful was successful was successful was successful was successful ended in failure SMA1440 (and 10% acetone) in marking ink E 4 was successful ended in failure was successful was successful was successful ended in failure SMA1440 (and 10% acetone) in marking ink F five was successful was successful was successful was successful was successful ended in failure SMA1440 (and 3% acetone) in Ink A 4 was successful was successful ended in failure was successful was successful was successful SMA1440 (and 3% acetone) in marking ink B 3 was successful was successful was successful was successful was successful ended in failure SMA1440 (and 3% acetone) in marking ink C 4 was successful was successful ended in failure was successful was successful was successful SMA1440 (and 3% acetone) in marking ink D 4 was successful was successful was successful was successful was successful was successful SMA1440 (and 3% acetone) in marking ink E 4 was successful was successful was successful was successful was successful was successful SMA1440 (and 3% acetone) in marking ink F 3 was successful was successful was successful was successful was successful was successful

Table 5. (continued)

immediately 1 h 1 h immediately 1 h 1 h soaking in chilled water soaking in alkaline solution 75C Composition scraping scraping adhesive tape 610 scraping scraping adhesive tape 610 Control A was successful was successful was successful ended in failure ended in failure ended in failure Control B was successful was successful was successful ended in failure ended in failure ended in failure Control C was successful was successful ended in failure ended in failure ended in failure ended in failure Control D was successful was successful ended in failure ended in failure ended in failure ended in failure Control E was successful was successful was successful ended in failure ended in failure ended in failure Control F was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (in acetone) as primer A was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (in acetone) as primer B was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (in acetone) as primer C was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (in acetone) as primer D was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (in acetone) as E primer was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (in acetone) as primer coat F was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (in acetone) as primer A was successful was successful was successful NOT APPLICABLE* NOT APPLICABLE* NOT APPLICABLE* SMA1440 (in acetone) as primer B was successful was successful was successful NOT APPLICABLE* NOT APPLICABLE* NOT APPLICABLE* SMA1440 (in acetone) as primer C was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (in acetone) as primer D was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (in acetone) as E primer was successful was successful was successful NOT APPLICABLE* NOT APPLICABLE* NOT APPLICABLE* SMA1440 (in acetone) as primer coat F was successful was successful was successful NOT APPLICABLE* NOT APPLICABLE* NOT APPLICABLE* SMA1440 (and 10% acetone) in marking ink A was successful was successful was successful NOT APPLICABLE* NOT APPLICABLE* NOT APPLICABLE* SMA1440 (and 10% acetone) in marking ink B was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (and 10% acetone) in marking ink C was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (and 10% acetone) in marking ink D was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (and 10% acetone) in marking ink E was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (and 10% acetone) in marking ink F was successful was successful was successful NOT APPLICABLE* NOT APPLICABLE* NOT APPLICABLE* SMA1440 (and 3% acetone) in Ink A was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (and 3% acetone) in marking ink B was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (and 3% acetone) in marking ink C was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (and 3% acetone) in marking ink D was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (and 3% acetone) in marking ink E was successful was successful was successful ended in failure ended in failure ended in failure SMA1440 (and 3% acetone) in marking ink F was successful was successful was successful ended in failure ended in failure ended in failure

NOT APPLICABLE * = removal of marking ink too great to check (all marking ink removed)

The data shows that the ink formulation samples SMA3840 and SMA1440F exhibit improved performance. The SMA3840 tracer ink formulation showed some signs of improvement that indicate improved tracing ink removal over the control. The SMA1440F marking ink formulation showed no significant signs during routine tests (“in use”), but showed significant signs of removal during the alkaline rinse test. Testing was repeated several times on PET, EPET and PE, all showing good removal in the alkaline wash test.

2. EXAMPLE 2.

In this example, marking ink compositions that include a white UV curing ink with a scavenger and carrier medium were directly applied to the surface of polyethylene terephthalate (PET) and high density polyethylene (HDPE) samples and cured. The test sample removal additive was a styrene-maleic anhydride copolymer (SMA1440F, commercially available from Cray Valley USA, LLC) and the carrier medium was N-methyl-2-pyrrolidone (NMP, commercially available from Sigma Aldrich). Table 6 below shows the paint formulations and performance data.

Table 6

Composition of marking paint Test 1 Test 2 Test 3 marking ink 1 - commercially available white marking ink with UV curing ability for inkjet printing ~ 50% ~ 30% ~ 55% Ink 2 - Ink 1 + Removal Agent and Carrier ~ 85% ~ 95% ~ 98%

% of marking ink removed / flakes off (based on visual analysis)

The data show that almost 100% removal of the paint compositions according to the invention was observed compared to only 50-60% removal of the marking ink on standard control samples of the marking ink. On HDPE samples, the marking ink compositions of the invention exhibit greater than 50% removal of the marking ink compared to only about 10% removal of the marking ink for the marking ink standard control samples. The results of the marking ink compositions of the present invention comply with current recycling regulations published by the Polymer Waste Processors Association.

It will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the scope or spirit of the invention. Other embodiments of the present invention will become apparent to those skilled in the art upon consideration of the description and practice of the invention described herein. The description and examples are intended to be illustrative only, with the true scope and spirit of the present invention set forth in the following claims.

Claims (64)

1. Composition of marking ink for digital printing technology on a plastic product, containing: (a) about 65 to about 85 weight percent of a base marking ink; (b) about 5 to about 20% by weight of an additive to help remove marking ink that has a glass transition temperature of less than about 130 ° C; and (c) about 5 to about 15 weight percent of a carrier medium capable of dissolving at least a portion of the paint stripper additive. 2. A marking ink composition according to claim 1, wherein the additive that helps to remove the marking ink comprises a copolymer of styrene and maleic anhydride. 3. The paint composition of claim 1, wherein the paint stripper has a glass transition temperature (Tg) in the range of about 50 ° C to about 110 ° C. 4. The paint composition of claim 1, wherein the paint stripper has a glass transition temperature (Tg) in the range of about 55 ° C to about 85 ° C. 5. The paint composition of claim 1, wherein the paint stripper has a glass transition temperature (Tg) in the range of about 55 ° C to about 65 ° C. 6. The paint composition of claim 1, wherein the paint stripper has an acid number in the range of about 150 mg KOH / g to about 205 mg KOH / g. 7. The paint composition of claim 1, wherein the paint stripper has an acid number in the range of about 165 mg KOH / g to about 205 mg KOH / g. 8. A marking paint composition according to claim 1, wherein the carrier medium comprises a solvent or monomer, or a combination thereof. 9. A marking paint composition according to claim 8, wherein the solvent comprises at least one aprotic solvent. 10. The marking paint composition of claim 8, wherein the solvent comprises N-methyl-2-pyrrolidone (NMP) or acetone, or a combination thereof. 11. The marking ink composition of claim 8, wherein the monomer comprises at least one acrylic monomer. 12. The marking ink composition of claim 11, wherein the acrylic monomer comprises: 1,3-butylene glycol diacrylate, 1,6-hexanediol diacrylate, 1,3-butylene glycol dimethacrylate, isobornyl acrylate or isodecyl methacrylate, or a combination thereof. 13. A marking ink composition according to claim 1, wherein the primary marking ink comprises a UV curable marking ink. 14. The marking ink composition of claim 1, wherein the marking ink composition is a UV curable composition. 15. Composition of marking ink for digital printing technology on a plastic product, containing: (a) about 65 to about 85 weight percent of a base marking ink; (b) about 5 to about 20 weight percent of an additive that has an acid number in the range of about 100 mg KOH / g to about 250 mg KOH / g; and (c) about 5 to about 15 weight percent of a carrier medium capable of dissolving at least a portion of the paint stripper additive. 16. The marking ink composition of claim 15, wherein the marking ink remover comprises a styrene maleic anhydride copolymer. 17. The paint composition of claim 15, wherein the paint stripper has a glass transition temperature (Tg) in the range of about 50 ° C to about 130 ° C. 18. The paint composition of claim 15, wherein the paint stripper has a glass transition temperature (Tg) in the range of about 55 ° C to about 85 ° C. 19. The marking ink composition of claim 15, wherein the ink stripper has a glass transition temperature (Tg) in the range of about 55 ° C to about 65 ° C. 20. The paint composition of claim 15, wherein the paint stripper has an acid number in the range of about 150 mg KOH / g to about 205 mg KOH / g. 21. The paint composition of claim 15, wherein the paint stripper has an acid number in the range of about 165 mg KOH / g to about 205 mg KOH / g. 22. The marking ink composition of claim 15, wherein the carrier medium comprises a solvent or monomer, or a combination thereof. 23. A marking ink composition according to claim 22, wherein the solvent comprises at least one aprotic solvent. 24. A marking paint composition according to claim 22, wherein the solvent comprises N-methyl-2-pyrrolidone (NMP) or acetone, or a combination thereof. 25. The marking ink composition of claim 22, wherein the monomer comprises at least one acrylic monomer. 26. A marking paint composition according to claim 25, wherein the acrylic monomer comprises: 1,3-butylene glycol diacrylate, 1,6-hexanediol diacrylate, 1,3-butylene glycol dimethacrylate, isobornyl acrylate or isodecyl methacrylate, or a combination thereof. 27. A marking ink composition according to claim 15, wherein the base marking ink comprises a UV curable marking ink. 28. The marking ink composition of claim 15, wherein the marking ink composition is a UV curable composition. 29. Recyclable plastic product, containing: a curved outer surface with an image digitally printed directly onto the curved outer surface, the image containing cured drops of marking ink, and the drops of marking ink contain the composition of claim 1; wherein the digitally printed image has an adhesion index of at least 6.0 and up to 9.0, and the removal additive is configured to separate the cured drops of marking ink from the curved outer surface or weaken the adhesion with the curved outer surface in the case of when the digitally printed image is exposed to a basic solution at an elevated temperature of at least about 70 ° C. 30. A plastic product according to claim 29, wherein the product comprises a plastic container. 31. A plastic product according to claim 30, wherein the plastic container is a bottle. 32. A plastics article according to claim 29, wherein the paint stripper comprises a styrene maleic anhydride copolymer. 33. The plastics article of claim 29, wherein the paint stripper has a glass transition temperature (Tg) in the range of about 50 ° C to about 110 ° C. 34. The plastics article of claim 29, wherein the descaling agent has a glass transition temperature (Tg) in the range of about 55 ° C to about 85 ° C. 35. The plastic article of claim 29, wherein the descaling agent has a glass transition temperature (Tg) in the range of about 55 ° C to about 65 ° C. 36. The plastics article of claim 29, wherein the descaling agent has an acid number in the range of about 150 mg KOH / g to about 205 mg KOH / g. 37. The plastics article of claim 29, wherein the descaling agent has an acid number in the range of about 165 mg KOH / g to about 205 mg KOH / g. 38. A plastic article according to claim 29, wherein the article consists of one or more of the following materials: polyethylene, polyethylene terephthalate, high density polyethylene and polypropylene. 39. The plastic article of claim 29, wherein the removal aid is configured to separate the cured droplets of the marking ink from the curved outer surface or weaken adhesion to the curved outer surface when the digitally printed image is exposed to the base solution with a pH in the range from about 12-13 at an elevated temperature in the range from about 70 ° C to 90 ° C. 40. A plastic article according to claim 39, wherein after exposure to the base solution at an elevated temperature, at least about 90% by weight of the cured drops of marking ink are separated from the curved outer surface of the article. 41. A plastic article according to claim. 29, wherein the digitally printed image comprises a base coat including a plurality of cured drops of base coat marking ink and an additional coating including a plurality of cured drops of an additional coating marking ink, wherein additional coating is applied to at least a portion of the base coat. 42. A method for removing a cured marking paint from a plastic container, the method comprising: (a) providing a plastic container that has a curved outer surface with an image digitally printed directly onto the curved outer surface of a plastic container using a drop-at-the-right-time inkjet method, the image containing cured drops of marking paints applied directly to the curved outer surface of a plastic container having an adhesion rating of at least 6.0 and up to about 9.0, and the marking ink droplets comprise the composition of claim 1; (b) processing at least a portion of the digitally printed image of the plastic container with a base solution at an elevated temperature of at least about 70 ° C; and (c) removing at least a portion of the digitally printed image from the curved outer surface to which the image has been applied. 43. The method of claim 42, wherein the container is a bottle. 44. The method of claim 42, wherein the paint stripping additive comprises a styrene maleic anhydride copolymer. 45. The method of claim 42, wherein the paint stripper has a glass transition temperature (Tg) in the range of about 50 ° C to about 110 ° C. 46. The method of claim 42, wherein the paint stripper has a glass transition temperature (Tg) in the range of about 55 ° C to about 85 ° C. 47. The method of claim 42, wherein the paint stripper has a glass transition temperature (Tg) in the range of about 55 ° C to about 65 ° C. 48. The method of claim 42, wherein the descaling agent has an acid number in the range of about 150 mg KOH / g to about 205 mg KOH / g. 49. The method of claim 42, wherein the descaling agent has an acid number in the range of about 165 mg KOH / g to about 205 mg KOH / g. 50. The method of claim 42, wherein the stock solution is an aqueous solution with a pH in the range of about 12-13, and wherein the elevated temperature is in the range of about 70 ° C to 90 ° C. 51. The method of claim 42, wherein the plastic container consists of one or more of the following materials: polyethylene, polyethylene terephthalate, high density polyethylene, and polypropylene. 52. The method of claim 42, wherein the step of removing comprises scraping or wiping off the marking ink from the container after processing the image with the base solution. 53. The method of claim 42, wherein the marking ink is mechanically removed in the form of flakes or film.

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