Ink for recyclable plastics

Abstract

The present invention provides a two-part ink or coating system, where Part A comprises one or more hydroxyl-functional resins, one or more aminoplast crosslinkers, one or more polyester polyols, and one or more solvents, and Part B comprises an acid catalyst. Parts A and B are combined immediately prior to application onto a substrate. The ink or coating system of the present invention is resistant to removal from polyolefin film substrates when subjected to high-temperature caustic cleaning solutions. When applied as an overcoat (backing coat) over conventional inks printed on polyolefin film substrates, the ink or coating system of the present invention also prevents removal of the conventional ink from the polyolefin substrate when subjected to high-temperature caustic cleaning solutions. Advantageously, use of the ink and coating system of the present invention reduces ink staining and contamination of recycled PET flakes.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 117,072, filed November 23, 2020, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to ink and coating compositions that facilitate the recycling of plastic substrates. The inks and coatings of the present invention are applied to plastic articles, such as labels, such as polymeric films applied to polyethylene terephthalate (PET) bottles. The inks and coatings of the present invention are not removed from the labels by hot caustic washes, are not dissolved in hot caustic washes, and therefore do not contaminate recycled plastic articles. [Background technology]

[0003] Full-coverage shrink sleeve labels are now a very popular option for use on consumer products such as food and beverage containers and polyethylene terephthalate (PET) containers. Shrink sleeve labels are attractive and convenient for consumers and commercially attractive to brand owners. However, while they are considered a success story by many, they pose challenges for the recycling industry. Shrink sleeve labels are particularly problematic when it comes to recycling PET bottles; the bottle and the label contained thereon enter the recycling process together and are very difficult to separate downstream. In addition, if the ink printed on the label dissolves in the hot caustic wash solutions commonly used to remove the label, the ink can contaminate the wash solutions, which in turn can cause discoloration of recycled polyester flakes. This discoloration of the flakes reduces their quality, thereby reducing the value of the recycled PET flakes. Even more detrimental, this can lead to increased wastewater treatment costs and potential environmental issues with municipal water sources and the Environmental Protection Agency (EPA).

[0004] Of the films typically used to make full-coverage shrink sleeve labels, polyethylene terephthalate glycol (PETG) is often the most problematic for recyclers because it tends to sink with the PET flakes from the bottles during the wash water step, after which the PET flakes tend to clump together and become very difficult to separate and remove from the process.

[0005] In response to this problem, a newly developed polymer called crystallizable PETG resin has been shown to be fully recyclable along with the PET flakes from bottles. In this process, the ink printed on the crystallizable PETG film is preferably completely removed during a hot caustic (NaOH solution) washing cycle, so that the recycled PET bottles and crystallizable PETG label film are of high quality (minimal coloration, good physical properties, e.g., resistance).

[0006] Alternatively, manufacturers of polyolefin-based films, such as polyethylene or polypropylene, have found an opportunity to offer a different solution to this problem by designing "floatable" polyolefin-based shrink films. Floatable polyolefin films can be used as full-coverage shrink sleeves on PET containers; because they float in water, they do not interfere with the recycling process and can be easily separated from the PET flakes during the settling / floating step of the process. Therefore, inks and coatings printed on these floatable films preferably remain on the label to prevent contamination of the caustic wash solution and the recycled PET flakes.

[0007] The current state of ink technology is that inks are not resistant to NaOH solutions and are therefore soluble in the hot caustic wash solution used in the recycling process. Hot caustic wash solutions are typically water at 85°C containing up to 3% NaOH and nonionic surfactants with detergent properties. Caustic-soluble ink chemicals are undesirable because they stain the recycled PET flakes and severely contaminate the wash water.

[0008] EP 2 987 822 A1 discloses a method for the continuous recovery of printed thin-walled PETG substrates, in which the ink is removed from the substrate during the recycling process using a treatment composition. The treatment composition is an aqueous azeotropic mixture of organic low molecular weight polar solvents selected from the group consisting of ketones, aldehydes, alcohols, and esters. Exemplary binder systems that can be removed with the treatment composition are styrene-acrylic copolymers or polyamides.

[0009] U.S. Patent No. 6,147,041 describes removable inks containing, as the main vehicle components, (A) a urethane resin and / or an acrylic resin, and (B) one or more materials selected from the group consisting of styrene-acrylic acid copolymers, styrene-maleic acid resins, rosin-maleic acid resins, and phenolic resins. The removable inks may further contain a cellulose resin as a vehicle component. An organic solvent is an essential component. These inks are removed from plastic articles using an aqueous alkaline solution.

[0010] WO 2021 / 081288 discloses ink compositions that are removed from plastic substrates such as labels in a hot caustic cleaning solution. When removed from the plastic substrate, these inks are poorly soluble in the hot caustic cleaning solution and precipitate, which is then filtered from the hot caustic solution.

[0011] U.S. Patent No. 5,338,785 discloses flexible packaging printing inks containing polyethylene glycol methacrylate / polyamide copolymer resin, pigment, solvent, and cellulose acetate butyrate. These inks may contain ketone resins. Resistance to alkaline solutions was not tested or discussed.

[0012] EP 2 061 848 A1 describes an inkjet ink composition comprising an organic solvent, a solvent-soluble binder resin, and a water-insoluble quinone dye. The binder resin has functional groups capable of interacting with the quinone dye, such as aromatic or polar functional groups, e.g., hydroxyl and / or carboxyl groups. The binder resins include cellulose resins and ketone resins. Resistance to alkaline solutions was not tested or discussed.

[0013] WO 2019 / 204994 discloses an alcohol-soluble printing ink composition comprising a polyurethane binder, a solvent, and a cellulose alkylate (as an antiblocking agent).

[0014] WO 2004 / 104121 discloses an aminoplast crosslinker for crosslinking coating systems containing carboxyalkyl cellulose esters. The crosslinking of the composition is catalyzed by PTSA. The reactive functional groups of the resin include hydroxyl, carboxyl, epoxy, and amine functional groups.

[0015] U.S. Patent No. 4,551,492 discloses a polyester coating composition consisting essentially of a binder consisting essentially of a polyester resin, a partially butylated melamine crosslinker resin, a polyurea plasticizer, a polyethylene vinyl acetate copolymer dispersion, and a mixture of low-viscosity and high-viscosity cellulose acetate butyrate. The objective was to increase the solids content of the composition from 14% to 18%. This was achieved by reducing the amount of cellulose acetate butyrate and increasing the amount of melamine crosslinker in addition to the polyester resin, resulting in the use of more crosslinker compared to the polyester resin. The composition requires a significantly higher amount of melamine crosslinker to provide satisfactory properties.

[0016] Therefore, there is a need to provide a solution where the ink will stay permanently on the label film, as opposed to being removable, so that when the label film is removed from the plastic bottle, the ink is removed as well, and will not stain or otherwise contaminate the recycled flakes derived from the plastic bottle. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] European Patent Application Publication No. 2987822 [Patent Document 2] U.S. Patent No. 6,147,041 [Patent Document 3] International Publication No. 2021 / 081288 [Patent Document 4] U.S. Patent No. 5,338,785 [Patent Document 5] European Patent Application Publication No. 2061848 [Patent Document 6] International Publication No. 2019 / 204994 [Patent Document 7] International Publication No. 2004 / 104121 [Patent Document 8] U.S. Patent No. 4,551,492 Summary of the Invention [Problem to be solved by the invention]

[0018] The present invention provides ink and coating compositions that, when applied to a label placed on a plastic article (e.g., a plastic bottle), are not removed from the label during the high-temperature caustic wash of the recycling process. The present invention also provides a method for applying the ink or coating composition to a label substrate. When applied as a topcoat or overprint varnish over other inks printed on the label, the compositions of the present invention also prevent removal of the other inks from the label. [Means for solving the problem]

[0019] In a particular aspect, the present invention provides a method for producing a medicament for the treatment of a pulmonary arthritis, comprising: (a) a part A that is a composition, i. 5% to 40% by weight, based on the total weight of the composition of Part A, of one or more hydroxyl-functional resins, wherein at least one resin is cellulose acetate butyrate; ii. 0.5% to 10% by weight, based on the total weight of the Part A composition, of one or more aminoplast crosslinkers; iii. 0.5% to 10% by weight, based on the total weight of the Part A composition, of one or more polyester polyols; and iv. Part A comprising 5% to 50% by weight of one or more solvents, based on the total weight of the Part A composition; (b) Part B, which is one or more acid catalysts.

[0020] In another aspect, the present invention provides a method for producing a composition comprising: (a) providing a floatable polyolefin film substrate; (b) printing and drying or curing one or more inks on a substrate; (c) applying an ink or coating system of the present invention over the one or more printed inks; and (d) drying or curing the ink or coating system The present invention provides a method for preparing a printed label, comprising:

[0021] In a preferred embodiment, the label is a floatable polyolefin film. In another embodiment, the label is applied to a plastic article, such as a container or bottle, and the article is recyclable. In a preferred embodiment, the plastic article is a PET bottle. [Brief explanation of the drawings]

[0022] [Figure 1] Figure 1 is a flow chart showing a typical PET recycling process. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention provides ink and coating compositions that are resistant to removal by hot caustic washes, such as those used in plastic recycling processes. The inks and coatings of the present invention are not removed, and when used as coatings (e.g., as backing white coatings over conventionally printed inks on transparent shrink films), the inks and coatings of the present invention prevent removal of the inks they are printed on during the recycling process. As a result, the recycled PET flakes so obtained are not stained or contaminated by the ink.

[0024] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of any subject matter claimed.

[0025] Headings are for organizational purposes only and are not intended to limit the invention in any way.

[0026] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. All patents, patent applications, published applications and publications, websites, and other published materials mentioned throughout this disclosure are incorporated by reference in their entirety for any purpose unless otherwise noted. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, preferred methods are described.

[0027] definition As used herein, the use of the singular includes the plural unless specifically stated otherwise. As used herein, the singular forms ("a," "an," and "the" in the foreign language specification of this application) are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0028] In this application, the use of "or" means "and / or" unless stated otherwise. Also, if clear from the context in which it is used, "and" may be interpreted as "or," as in a list of alternative elements, none of which can all be true or present at once.

[0029] As used herein, the terms "comprises" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Furthermore, to the extent the terms "includes," "having," "has," "with," "composed," "comprised," or variations thereof, are used in either the detailed description or the claims, such terms are intended to be inclusive in the same manner as the term "comprising."

[0030] As used herein, ranges and amounts can be expressed as "about" a particular value or range. "About" is intended to include the exact amount. Thus, "about 5 percent" means "about 5 percent," and also means "5 percent." "About" means within typical experimental error for the intended use or purpose.

[0031] When a range of numerical values ​​is recited, it is understood to include the endpoints, whether or not specifically recited, all values ​​within that range, and all narrower ranges within that range.

[0032] Throughout this disclosure, all parts and percentages are by weight (wt % or mass % based on total weight) and all temperatures are in °C unless otherwise indicated.

[0033] As used herein, "substrate" means any surface or object to which an ink or coating can be applied. Substrates include, but are not limited to, cellulosic substrates, paper, paperboard, fabrics (e.g., cotton), leather, textiles, felt, concrete, masonry, stone, plastics, plastic or polymer films, spunbond nonwovens (e.g., made of polypropylene, polyester, etc.), glass, ceramic, metal, wood, composites, combinations thereof, and the like. The substrate may have one or more layers of metal or metal oxide, or other inorganic materials. Nonwoven substrates are particularly preferred. For purposes of the present invention, plastic substrates, particularly shrink films and recyclable plastic substrates, are preferred substrates.

[0034] As used herein, the term "article" or "articles" refers to a substrate or an article of manufacture. Examples of articles include, but are not limited to, substrates such as cellulosic substrates, paper, paperboard, plastic, plastic or polymeric films, glass, ceramic, metal, composites, and articles of manufacture such as publications (e.g., booklets), labels, and packaging materials (e.g., cardboard sheets or corrugated cardboard), containers (e.g., bottles, cans), polyolefins (e.g., polyethylene or polypropylene), polyesters (e.g., polyethylene terephthalate), metallized foils (e.g., laminated aluminum foil), metallized polyesters, and metal containers. For purposes of the present invention, plastic articles, particularly shrink films and recyclable plastic substrates, are preferred substrates.

[0035] As used herein, "inks and coatings," "ink," and "coatings" are used interchangeably and refer to the compositions of the present invention or, where specified, compositions found in the prior art (comparison). Inks and coatings typically contain resins, solvents, and optionally, in some cases, colorants. Coatings are often considered to be colorless or transparent, while inks typically contain colorants.

[0036] As used herein, "hot caustic wash solution" or "hot caustic solution" refers to an aqueous solution containing water and a base heated to about 85° C. to 90° C. For example, the hot caustic wash solution may contain water and about 3% to 20% sodium hydroxide (NaOH).

[0037] When the terms "consist of," "consists of," or "consisting of" are used in the body of a claim, the claim term offset with "consist of," "consists of," and / or "consisting of" is limited to the elements recited immediately following "consist of," "consists of," or "consisting of" and is closed to unrecited elements associated with that particular claim term. The term "combination thereof," when included in the list of recited elements following "consist of," "consists of," or "consisting of," refers to a combination of only two or more of the recited elements. For example, if a claim recites "a solvent selected from the group consisting of only alcohols, ketones, acetates, and combinations thereof," this means that the claim can include only those recited solvents; i.e., "combination thereof" refers to a combination of only alcohols, ketones, and acetates.

[0038] Recycling Process The recycling process is illustrated in Figure 1. A general description of a typical mechanical recycling process for PET from post-consumer bottle material is as follows: (a) Collection of labelled post-consumer PET bottles from roadside or municipal recycling facilities. (b) Separating labeled PET bottles from compacted bales in a mechanical singulator. (c) Initial washing of the entire labeled bottle in a mild caustic / detergent water bath. (d) NIRF (near-infrared fluorescence) or manual sorting of PET from non-PET contaminants. (e) Wet or dry mechanical crushing of whole labeled bottles. (f) Thorough cleaning in high shear tanks with hot caustic water + detergent. (g) Settling / flotation tanks to remove light materials (caps, lids, rings, and polyolefin-based labels, as well as floating closures) from heavy materials (PET flakes from bottles). (h) Drainage / drying / wet classification of washed recycled PET flakes.

[0039] The recycled PET flakes can then be converted into pellets and used in any application that PET is used for, such as making new PET bottles.

[0040] Referring to the diagram, bales of mixed plastics (1) flow through a singulator (2) to separate the different types of plastics. PET bottles are typically subjected to a whole-bottle wash in a mild caustic / detergent water bath (3) to remove ink. The clean PET bottles are sorted either by NIRF or by hand sorting (4). Sorting separates non-PET material into mixed bales (5). Whole PET bottles (clear / blue, green) are separated (6). Note that the labels and caps are still on the bottles at this stage. The PET bottles are again hand sorted (7) and flow through a wet or dry crusher (8) to produce mixed flakes (i.e., PET flakes from the bottles and flakes from the caps and labels). After crushing, the mixed flakes are dewatered (9) and dried (10). At this point, the mixed flakes may optionally be subjected to a wet classification step to separate the mixed flakes by size (11). The mixed flakes are transferred to a dirty silo (12) and then subjected to a pre-rinse (13). The mixed flakes are dewatered (14). Next, the mixed flakes are transferred to a high-shear washing reactor (15), where they are subjected to a hot caustic wash solution (caustic water + detergent), which is designed to remove any ink remaining on the flakes. The washed mixed flakes are then dewatered (16) and transferred to a settling / flotation tank (17). The non-PET flakes, being lighter than the PET flakes (the floatable stream), float to the top of the tank and are removed (18). The PET flakes (19) settle to the bottom of the settling / flotation tank and are processed by dewatering (20) and drying (21). The PET flakes are optionally wet classified (22) to separate the PET flakes by size. The PET flakes are optionally subjected to flake screening (23). The clean PET flake stream (24) can be used to make other products such as plastic bottles (25).

[0041] Ink and coating compositions and uses thereof The present invention provides ink and coating compositions that are resistant to removal from substrates when subjected to hot caustic cleaning solutions, such as during the recycling of plastic articles. The ink and coating compositions of the present invention also do not dissolve in hot caustic solutions. Therefore, contamination and staining of recycled PET flakes is reduced or eliminated by the use of the inks and coatings of the present invention. When used as a topcoat or overprint varnish applied over other inks, the compositions of the present invention also prevent the removal of the other inks from the substrate.

[0042] The ink and coating compositions of the present invention are provided as two-part systems. The ink and coating systems of the present invention are based on a two-part acid catalyst / aminoplast crosslinking chemistry in combination with one or more hydroxyl-functional resins. The Part A composition includes one or more hydroxyl-functional resins, one or more aminoplast crosslinkers, one or more polyester polyols, and one or more solvents. In a preferred embodiment, at least one hydroxyl-functional resin is a cellulose acetate butyrate (CAB) resin. Part B includes one or more acid catalysts that are reactive with the aminoplast crosslinkers.

[0043] The composition of Part A comprises one or more hydroxyl-functional resins. Suitable resins include, but are not limited to, acrylics, polyester diols, alkyds, polyurethanes, cellulose acetate butyrate (CAB), cellulose acetate propionate (CAP), ketone formaldehyde, and combinations thereof. In a preferred embodiment, at least one resin is CAB.

[0044] In certain embodiments, two or more CAB resins are included. In some embodiments, CAB resins with different viscosities can be used in different amounts to adjust the viscosity of the composition. For example, if a composition contains a first CAB resin and the viscosity of the composition is too high for its intended purpose (such as flexographic printing), a second CAB resin with a lower viscosity than the first CAB resin can be added in an amount sufficient to adjust the viscosity accordingly. Those skilled in the art will select a CAB resin with an appropriate viscosity to achieve the desired viscosity for the printing method being used.

[0045] The Part A compositions of the present invention typically contain from about 5% to about 40% by weight of one or more hydroxyl-functional resins, based on the total weight of the Part A composition. The amount of one or more hydroxyl-functional resins is by dry weight (i.e., resin solids). For example, the Part A composition may contain from about 5% to about 30% by weight, or from about 5% to about 20% by weight, or from about 5% to about 10% by weight, or from about 10% to about 40% by weight, or from about 10% to about 30% by weight, or from about 10% to about 20% by weight, or from about 20% to about 40% by weight, or from about 20% to about 30% by weight, or from about 30% to about 40% by weight. In certain embodiments, the resin can be provided as a solution or dispersion, and the amount of solution or dispersion is adjusted to achieve the desired amount of resin solids. For example, if the hydroxyl-functional resin is supplied as a dispersion having 40% solids, the amount of dispersion that would be added would be 12.5% ​​by weight of the dispersion to arrive at 5% by weight of the hydroxyl-functional resin.

[0046] The Part A composition of the present invention includes one or more aminoplast crosslinkers. Suitable aminoplast crosslinkers include, but are not limited to, melamine-based resins, urea-based resins, and combinations thereof. The Part A composition of the present invention typically includes about 0.5% to 10% by weight of one or more aminoplast crosslinkers, based on the total weight of the Part A composition. The amount of one or more aminoplast crosslinkers is the weight of the actual crosslinker. For example, the Part A composition may contain about 0.5% to 5% by weight, or about 0.5% to about 1% by weight of the aminoplast crosslinker. In certain embodiments, the crosslinker can be provided as a solution or dispersion, and the amount of solution or dispersion is adjusted to achieve the desired amount of crosslinker itself.

[0047] The Part A composition of the present invention includes one or more polyester polyols. Suitable polyester polyols include, but are not limited to, K-Flex 188, K-Flex 148, K-Flex 171-90, and combinations thereof (all from King Industries). The Part A composition of the present invention typically includes from about 0.5 wt. % to about 10 wt. % of the polyester polyol, based on the total weight of the Part A composition. For example, the Part A composition may contain from about 0.5 wt. % to about 5 wt. % or from about 0.5 wt. % to about 1 wt. % of the polyester polyol.

[0048] The Part A compositions of the present invention include one or more solvents. Suitable solvents include, but are not limited to, alcohols, aliphatic hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, ketones, aldehydes, ethers, esters, and combinations thereof. The Part A compositions of the present invention typically include about 5% to about 50% by weight of one or more solvents, based on the total weight of the Part A composition. For example, the Part A composition may contain about 5% to about 40% by weight, or about 5% to about 30% by weight, or about 5% to about 20% by weight, or about 5% to about 10% by weight, or about 10% to about 50% by weight, or about 10% to about 40% by weight, or about 10% to about 30% by weight, or about 10% to about 20% by weight, or about 20% to about 50% by weight, or about 20% to about 40% by weight, or about 20% to about 30% by weight. The Part A compositions preferably do not contain water. However, small amounts of water may be present as an impurity in the materials used to prepare the composition. If water is present, it is preferably present in an amount less than 0.5% by weight, based on the total weight of the Part A composition.

[0049] The Part A composition of the present invention may further comprise one or more non-hydroxyl functional resins. Non-hydroxyl functional resins include, but are not limited to, polyesters, polyurethanes, polyamides, ketone resins, aldehyde resins, alkyd resins, phenol-formaldehyde resins, rosin resins, hydrocarbon resins, and combinations thereof. Such resins can help improve pigment wetting, gloss, rheology, chemical resistance, anti-blocking properties, and flexibility. When present, non-hydroxyl functional resins are typically present in an amount of about 0.5% to about 40% by weight, based on the total weight of the Part A composition. The amount of non-hydroxyl functional resin is by dry weight (i.e., resin solids). For example, the Part A composition may contain non-hydroxyl functional resin in an amount of about 0.5% to about 30% by weight, or about 0.5% to about 20% by weight, or about 0.5% to about 10% by weight, or about 0.5% to about 1% by weight, or about 1% to about 40% by weight, or about 1% to about 30% by weight, or about 1% to about 20% by weight, or about 1% to about 10% by weight.

[0050] The Part A compositions of the present invention may further comprise one or more fillers. Suitable fillers include, but are not limited to, clay, talc, calcium carbonate, magnesium carbonate, silica, and combinations thereof. When present, the filler is typically present in an amount of about 0.5% to about 10% by weight, based on the total weight of the Part A composition. For example, the Part A composition may contain about 0.5% to 5% by weight, or about 0.5% to about 1% by weight of the filler.

[0051] The Part A composition of the present invention may further comprise one or more additives. Suitable additives include, but are not limited to, adhesion promoters, silicones, light stabilizers, photobrighteners, degassing additives, ammonia, flow promoters, antifoaming agents, antioxidants, stabilizers, surfactants, dispersants, plasticizers, rheology additives, waxes, silicones, and combinations thereof. When present, additives are each individually present in an amount of about 0.1% to about 5% by weight, based on the total weight of the Part A composition.

[0052] The Part A composition of the present invention may further comprise one or more colorants. Suitable colorants include, but are not limited to, organic or inorganic pigments and dyes. Dyes include, but are not limited to, azo dyes, anthraquinone dyes, xanthene dyes, azine dyes, combinations thereof, and the like. The organic pigment may be, for example, one or a combination of pigments such as Pigment Yellow Nos. 12, 13, 14, 17, 74, 83, 114, 126, 127, 174, 188; Pigment Red Nos. 2, 22, 23, 48:1, 48:2, 52, 52:1, 53, 57:1, 112, 122, 166, 170, 184, 202, 266, 269; Pigment Orange Nos. 5, 16, 34, 36; Pigment Blue Nos. 15, 15:3, 15:4; Pigment Violet Nos. 3, 23, 27; and / or Pigment Green No. 7. The inorganic pigment can be one of the following non-limiting pigments: iron oxide, titanium dioxide, chromium oxide, ferric iron oxide, black iron oxide, Pigment Black No. 7, and / or Pigment White Nos. 6 and 7. Other organic and inorganic pigments and dyes can also be employed, as well as combinations to achieve the desired color. The colorant is typically provided as a colorant dispersion. When present, the colorant dispersion is typically included in the Part A composition of the present invention in an amount of about 35% to about 50% by weight, based on the total weight of the Part A composition. For example, the colorant dispersion can be present in an amount of about 35% to about 45% by weight, or about 35% to about 40% by weight, or about 40% to about 50% by weight, or about 40% to about 45% by weight, or about 45% to about 50% by weight.

[0053] The composition of Part B includes one or more acid catalysts. The acid catalyst reacts with the aminoplast crosslinker. Suitable acid catalysts include, but are not limited to, paratoluenesulfonic acid (p-TSA), dodecylbenzenesulfonic acid (DDBSA), dinonylnaphthalenesulfonic acid (DNNSA), dinonylnaphthalenedisulfonic acid (DNNDSA), acid phosphates, carboxylic acids, and combinations thereof.

[0054] Parts A and B are stored separately and mixed immediately before use. The composition of Part A and the acid catalyst of Part B are mixed in a ratio of Part A:Part B of about 90:10 to 95:5.

[0055] In a preferred embodiment, the inks and coatings of the present invention are applied to a label substrate for use on plastic, preferably PET bottles. In one particular embodiment, the label substrate is a shrink wrap film. In a preferred embodiment, the shrink wrap film is a floatable polyolefin film. The floatable film is easily separated from the PET flakes during recycling.

[0056] The inks and coatings of the present invention are not removed from the label substrate during the recycling process. They remain on the film and are separated from the wash solution along with the label substrate, which may be floatable. Therefore, they do not dissolve in the hot caustic wash solution and do not contaminate either the wash solution or the PET flakes. Therefore, the use of the inks and coatings of the present invention allows for the recovery of clean recycled PET flakes.

[0057] In certain embodiments, the inks and coatings of the present invention are used as backing compositions to prevent the removal of other inks from the label substrate. In these embodiments, any colored ink is first printed onto the substrate. The colored ink is then overprinted with the ink or coating of the present invention, preferably at 100% coverage of the colored ink. Thus, the colored ink overprinted with the ink or coating of the present invention is protected from the hot caustic wash solution during recycling and is not removed from the label substrate. Thus, the colored ink is also separated from the wash solution along with the substrate, which may float during recycling.

[0058] When used as a backing composition (printed over other inks as a topcoat / overprint varnish), the inks and coatings of the present invention can be white or transparent. White backing compositions contain a white pigment, such as titanium dioxide (TiO2), in the Part A composition. White backing compositions typically contain TiO2 in an amount of about 10% to 40% by weight, based on the total weight of the Part A composition. When backing compositions do not contain a white pigment, they are transparent coatings.

[0059] To ensure that the ink was not removed from the label during the simulated recycling process and / or dissolved in the hot caustic wash solution, crushed PET flakes (PET ラベル The color of PET flakes (PET) without labels was subjected to a simulated recycling process. クリーン ) compared to the color of PET ラベル But PET クリーン The CIELAB color values, L, defined in the CIELAB color space by the Commission Internationale de l'Eclairage (CIE) in 1976, were compared to see if the spectra matched. * a * b * is measured using a spectrophotometer (see Examples), where L * = brightness value; a * = red / green value, positive values ​​indicate the amount of red, negative values ​​indicate the amount of green; b * = Yellow / Blue value, positive values ​​indicate amount of yellow, negative values ​​indicate amount of blue.

[0060] ΔL * , Δa * , and Δb * The difference in color values ​​of the PET flakes, expressed as: ΔL * =L * ラベル -L * クリーン Δa * =a * ラベル -a * クリーン Δb * =b * ラベル -b * クリーン

[0061] PET ラベル Flakes and control PET クリーン Target values ​​for color change in flakes are established by the Association of Plastics Recyclers (APR). ラベル In the following cases, PET クリーン It is considered that the spectrum matches (spectral match). ΔL * =0±10.0 or 0±7.5 Δa * =0±2.5 or 0±2.0 Δb * =0±2.5 or 0±2.0

[0062] In a preferred embodiment, as established by the APR, PET ラベル PET is クリーン It is considered that the spectrum matches (spectral match) with the ΔL * =0±5.0 Δa * =0±1.5 Δb * =0±1.5

[0063] Most preferably, ΔL * , Δa * , and Δb * is zero.

[0064] The two-part ink and coating compositions of the present invention are suitable for flexographic and gravure printing, however, it should be understood that other types of printing may also be used. [Example]

[0065] The present invention is further described by the following non-limiting examples, which further illustrate the present invention and are not intended, nor should they be construed, to limit the scope of the invention.

[0066] Example 1. Two-component backing white coating The compositions of the present invention were prepared as two-component backing white coating compositions according to the formulations shown in Table 1.

[0067] [Table 1]

[0068] Part A and Part B were blended in a 95:5 ratio just prior to printing.

[0069] The composition was mixed using an Ultra Turrax T50 basic mixer at 3000-4000 rpm for 15-20 minutes.

[0070] Although Example 1 is formulated for use as a flexographic ink, it is well understood that the backing white can be reformulated to have viscosity and drying characteristics suitable for other printing methods, such as, for example, gravure printing.

[0071] Example 2. Evaluating PET flakes from a simulated recycling process The printed labels and PET flakes were subjected to a simulated recycling process as described below. The effectiveness of the compositions of the present invention to reduce or eliminate ink removal from the printed labels was evaluated by measuring color values ​​as described below.

[0072] method <Print> Individual yellow, magenta, cyan, and black printed labels were prepared by printing yellow, magenta, cyan, and black Solvawash inks (Sun Chemical Corp.) onto Taghleef polyolefin floatable shrink film. Solvawash GR ink (see formulations in Examples 1-7 of WO 2021 / 081288) is suitable for gravure printing and was applied to Taghleef SHAPE 360 shrink film. Solvawash FL ink (see Examples 15 and 16 of WO 2021 / 081288) is suitable for flexographic printing and was applied to Taghleef SHAPE 360 shrink film. The inks were applied using a Harper Blade Hand Proofer with a 360 lpi / 6.0 BCM anilox cylinder. The inks were dried for 5 seconds with a stream of hot air from a laboratory heat gun.

[0073] After the ink was allowed to dry, the inventive sample labels were overprinted with the backing white coating composition of Example 1 using a hand proofer as described above. The coating was allowed to dry, and the inventive sample labels were subjected to simulated recycling using PET flakes.

[0074] <Recycling simulation experiment> The labels and PET flakes were subjected to a simulation of the recycling process as described below. (1) 3g of label was cut into 0.25" x 0.25" pieces and blended with 100g of clean PET flakes. (2) 200 ml of a caustic solution containing 3 g of sodium hydroxide (NaOH) and 0.6 g of Triton X-100 surfactant was added to a beaker and heated to a temperature of 85° C. on a hot plate. (3) When the caustic solution reached 85°C, the label and PET flake mixture was added to the hot caustic solution and stirred at 1000 rpm for 15 minutes using a benchtop mixer. (4) After 15 minutes, the beaker was removed from the heat source and the solution was subjected to a precipitation / flotation step. During the precipitation / flotation step, the label flakes floated to the top and were removed. The remaining hot caustic solution containing the PET flakes was then strained through a filter (sieve or organza cloth). The solution was collected in a glass bottle. The PET flakes were collected in the filter. (5) The PET flakes were rinsed until the rinse water was clear or discoloration was minimal, and the flakes were dried. The PET flakes subjected to simulated recycling, together with the label overprinted with the white backing of Example 1, were then placed in a PET ラベル Identify as. (6) The control PET flake was clean PET flake that was subjected to a simulated recycling process, but without the label piece (i.e., PET flake only), and the PET クリーン is identified as

[0075] The color of the PET flakes was evaluated as described below.

[0076] <Evaluation of color change> The PET of the present invention ラベル Flakes, control PET クリーン The color values ​​of the flakes were measured as follows. (1) PET flakes were placed on the back of a Leneta card (non-fluorescent white paper) and pressed flat under the spectrophotometer. (2) The color of the PET flakes was measured using an X-Rite eXact Advanced XP spectrophotometer set at MO, D65 illuminant at a 10° angle. The L of each of the PET flakes of the present invention and the control PET flakes * a * b * Measure the value and ΔL * , Δa * , and Δb * Control PET flakes (PET クリーン ), as described above, the PET of the present invention ラベル ) was calculated.

[0077] The delta value of the PET flakes of the present invention isラベル Flakes and control PET クリーン The difference in colorimetric data between the flakes was calculated using the following formula: PET ラベル ΔL * =PET ラベル L * -PET クリーン L * PET ラベル Δa * =PET ラベル a * -PET クリーン a * PET ラベル Δb * =PET ラベル b * -PET クリーン b *

[0078] ΔL of PET flakes obtained from samples combining PET flakes with labels printed with Solvawash GR ink * , Δa * , and Δb * is shown in Table 2.

[0079] [Table 2]

[0080] ΔL of PET flake obtained from sample combining PET flake with label printed with Solvawash FL ink * , Δa * , and Δb * is shown in Table 3.

[0081] [Table 3]

[0082] The data in Tables 2 and 3 are from PET クリーン PET compared to flakes ラベル The flakes show a favorable small color change. ラベルFlakes are recycled PET without any printed labels クリーン The close spectral match to the PET flakes indicates that the ink from the printed label was not removed and / or dissolved in the hot caustic wash solution when the ink was overprinted with the composition of the present invention. ラベル ΔL of flakes * , Δa * , and Δb * The values ​​were significantly lower than the previously mentioned target values ​​for color change established by APR.

[0083] Although the present invention has been described in detail, including preferred embodiments thereof, it will be appreciated that those skilled in the art, upon consideration of this disclosure, may make modifications and / or improvements to the invention which are within the scope and spirit of the invention.

Claims

1. (a) Part A, which is a composition, i. 5% to 40% by weight, based on the total weight of the Part A composition, of one or more hydroxyl-functional resins, wherein at least one resin is a cellulose acetate butyrate resin; ii. 0.5% to 10% by weight, based on the total weight of the Part A composition, of one or more aminoplast crosslinkers; iii. 0.5% to 10% by weight, based on the total weight of the Part A composition, of one or more polyester polyols; and iv. Part A comprising 5% to 50% by weight of one or more solvents, based on the total weight of the composition of Part A; and (b) one or more acid catalysts, moieties B; wherein Part A and Part B are blended in a ratio of 90:10 to 95:

5.

2. 10. The ink or coating system of claim 1, wherein the one or more acid catalysts are selected from the group consisting of paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, acid phosphates, carboxylic acids, and combinations thereof.

3. 10. The ink or coating system of claim 1, wherein the one or more hydroxyl functional resins are selected from the group consisting of acrylics, polyester diols, alkyds, polyurethanes, cellulose acetate butyrates, ketone formaldehydes, and combinations thereof.

4. 10. The ink or coating system of claim 1, wherein the one or more aminoplast crosslinkers are selected from the group consisting of melamine-based resins, urea-based resins, and combinations thereof.

5. 5. The ink or coating system of claim 4, wherein the one or more aminoplast crosslinkers are selected from the group consisting of melamine-formaldehyde resins, urea-formaldehyde resins, and combinations thereof.

6. 6. The ink or coating system of any one of claims 1 to 5, wherein the Part A composition further comprises one or more additives selected from the group consisting of adhesion promoters, silicones, light stabilizers, light brighteners, degassing additives, ammonia, flow promoters, antifoaming agents, antioxidants, stabilizers, surfactants, dispersants, plasticizers, rheology additives, waxes, silicones, and combinations thereof, each additive independently present in an amount of 0.1 wt % to 5 wt %, based on the total weight of the Part A composition.

7. 7. The ink or coating system of any one of claims 1 to 6, wherein the Part A composition further comprises 10% to 40% by weight of titanium dioxide.

8. (a) providing a floatable polyolefin film substrate; (b) printing and drying or curing one or more inks onto the substrate; (c) applying the ink or coating system of any one of claims 1 to 7 onto the one or more printed inks; and (d) drying or curing the ink or coating system; 1. A method for producing a printed label, comprising:

9. 9. The method of claim 8, wherein the floatable polyolefin film is polyethylene or polypropylene.

10. A method for manufacturing a recyclable plastic container including a printed label, the method comprising the steps of manufacturing a printed label by the method of claim 8 or 9, and applying the printed label to the recyclable plastic container.

11. The method of claim 10, wherein the container is made from polyethylene terephthalate (PET).

12. A method for obtaining recycled PET flakes, comprising: (a) providing a recyclable plastic container manufactured according to the manufacturing method of claim 11; (b) immersing the plastic container in a hot caustic cleaning solution, i. the hot caustic cleaning solution removes printed labels from the plastic container; and ii. The printed ink and ink or coating system is not removed from the label and is not dissolved in the hot caustic cleaning solution; (c) obtaining undiscolored recycled PET flake from the ink and / or ink or coating system, wherein the recycled PET flake has a spectral match to a control PET flake from an unprinted, clean plastic container immersed in a hot caustic wash solution, as indicated by the difference in CIELAB color values ​​between the recycled PET flake and the control PET flake, and a ΔL ＊ = 0 ± 10.0, Δa ＊ = 0 ± 2.5, and Δb ＊ = 0 ± 2.5; A method comprising:

13. ΔL ＊ = 0 ± 5.0, Δa ＊ = 0 ± 1.5, and Δb ＊ 13. The method of claim 12, wherein: = 0 ± 1.

5.

14. 14. The method of claim 12 or 13, wherein the hot caustic solution comprises 3 g NaOH and 0.6 g surfactant in 200 ml of solution at a temperature of 85°C.

15. The method of claim 14, wherein the surfactant is a non-ionic surfactant.

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