Articles containing washable adhesive compositions

Abstract

The present disclosure provides an article of manufacture. In one embodiment, the article includes a first substrate and an adhesive layer in contact with the first substrate. The adhesive layer contains an adhesive composition. The adhesive composition comprises (i) an acrylic polymer consisting of polymerized units of (a) a first monomer that is a C4-C18 alkyl acrylate, and (b) a second monomer selected from the group consisting of acrylic acid, methacrylic acid, and optionally a C1-C3 alkyl acrylate containing a hydroxyl group. The adhesive composition further comprises (ii) at least one inorganic neutralizing agent, and (iii) at least one surfactant. The article includes a second substrate in contact with the adhesive layer.

Description

Background Art

[0001] Articles containing labels, such as labeled plastic containers, create difficulties in recycling the articles. The adhesive and / or label facestock typically remain on the article during the recycling process, which then requires additional energy and processing steps to make the plastic container clean and free of adhesive and label contaminants.

[0002] The art recognizes the need for marking plastic articles with improved recyclability. Specifically, there is a need to mark plastic articles with an adhesive layer that provides suitable adhesive properties; the adhesive layer can also be easily separated from the plastic article, thereby enabling the plastic article to be recycled. Summary of the invention

[0003] The present disclosure provides an article. In one embodiment, the article includes a first substrate and an adhesive layer in contact with the first substrate. The adhesive layer contains an adhesive composition. The adhesive composition comprises (i) an acrylic polymer composed of the following polymerized units: (a) a first monomer, the first monomer being an acrylic acid C4-C 18 The adhesive composition further comprises (ii) at least one inorganic neutralizing agent, and (iii) at least one surfactant. The article comprises a second substrate in contact with the adhesive layer.

[0004] definition

[0005] Any reference to the Periodic Table of the Elements is to the Periodic Table as published by CRC Press, Inc., 1990-1991. A group of elements in this table is referred to by a new notation for numbering the groups.

[0006] For purposes of U.S. patent practice, the contents of any referenced patent, patent application, or publication are incorporated by reference in their entirety (or their equivalent U.S. versions are incorporated by reference), particularly with respect to disclosure of definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure).

[0007] Numerical ranges disclosed herein include all values ​​from the lower limit to the upper limit, and include the lower limit and the upper limit. For ranges containing explicit values ​​(e.g., 1 or 2, or 3 to 5, or 6, or 7), any sub-range between any two explicit values ​​is included (e.g., the above range 1 to 7 includes sub-ranges of 1 to 2, 2 to 6, 5 to 7, 3 to 7, 5 to 6, etc.).

[0008] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percentages are based on weight and all test methods are current as of the filing date of this disclosure.

[0009] An "acrylic polymer" is a polymer containing polymerized acrylic acid monomers and optionally may contain at least one comonomer. As used herein, an "acrylic acid monomer" is a monomer having the following structure (I):

[0010] Structure (I)

[0011]

[0012] Where R1 is H or C1-C 18 An alkoxy group, and R2 is H or CH3. Non-limiting examples of acrylic monomers include acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters.

[0013] The term "alkyl" is a monovalent hydrocarbon. A "hydrocarbon" is a compound consisting only of hydrogen and carbon atoms and containing straight and / or branched chains.

[0014] The terms "amine" and "amino" refer to unsubstituted amines (e.g., NH3 and NH4 + ) and substituted amines (e.g., mono-substituted amines or di-substituted amines), wherein the substituents may include, for example, alkyl, cycloalkyl, heterocyclyl, alkenyl, and aryl groups.

[0015] The term "blend" or "polymer blend" as used refers to a mixture of two or more polymers. A blend may be miscible or immiscible (not phase separated at the molecular level). A blend may or may not be phase separated. A blend may or may not contain one or more domain configurations, as determined by transmission electron spectroscopy, light scattering, x-ray scattering, and other methods known in the art. A blend may be achieved by physically mixing two or more polymers at a macroscopic level (e.g., melt blending resins or compounding) or a microscopic level (e.g., simultaneously formed in the same reactor).

[0016] The term "composition" refers to a mixture of materials comprising the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0017] The terms "comprising", "including", "having" and their derivatives are not intended to exclude the presence of any additional components, steps or procedures, whether or not these components, steps or procedures are specifically disclosed. For the avoidance of any doubt, unless stated to the contrary, all compositions claimed by using the term "comprising" may include any additional additives, adjuvants or compounds, whether in polymeric form or otherwise. In contrast, the term "consisting essentially of excludes any other components, steps or procedures (except those that are not essential to operability) from the scope of any subsequent statements. The term "consisting of" excludes any components, steps or procedures that are not specifically described or listed. Unless otherwise stated, the term "or" refers to the listed members individually and in any combination. The use of the singular includes the use of the plural, and vice versa.

[0018] "Ethylene-based polymers" or "ethylene polymers" are polymers that contain a majority amount of polymerized ethylene, based on the weight of the polymer, and optionally may contain at least one comonomer. Ethylene-based polymers typically contain at least 50 mole percent (mol%) units derived from ethylene (based on the total amount of polymerizable monomers).

[0019] An "olefin-based polymer" is a polymer that contains a majority mole % of polymerized olefin monomer (based on the total amount of polymerizable monomers) and optionally may contain at least one comonomer. Non-limiting examples of olefin-based polymers include ethylene-based polymers and propylene-based polymers.

[0020] As used herein, the term "polymer" or "polymeric material" refers to a compound prepared by polymerizing monomers, whether monomers of the same type or different types, which provide multiple and / or repeating "units" or "monomer units" constituting the polymer in a polymerized form. Therefore, the general term polymer covers the term homopolymer, which is usually used to refer to polymers prepared from only one type of monomer, and the term copolymer, which is usually used to refer to polymers prepared from at least two types of monomers. It also covers all forms of copolymers, such as random copolymers, block copolymers, etc. The terms "ethylene / α-olefin polymer" and "propylene / α-olefin polymer" refer to copolymers prepared by polymerizing ethylene or propylene and one or more additional polymerizable α-olefin monomers, respectively, as described above. It should be noted that although polymers are often referred to as "made of" one or more specified monomers, "based on" a specified monomer or monomer type, "containing" a specified monomer content, etc., in this context, the term "monomer" should be understood to refer to the polymerized residue of the specified monomer rather than the unpolymerized substance. Generally, the polymers herein are referred to as "units" based on the polymerized form of the corresponding monomers.

[0021] A "propylene-based polymer" is a polymer that contains a major amount of polymerized propylene, based on the weight of the polymer, and optionally may include at least one comonomer. Propylene-based polymers typically contain at least 50 mole percent (mol%) units derived from propylene (based on the total amount of polymerizable monomers). The terms "propylene-based polymer" and "polypropylene" are used interchangeably.

[0022] Test Method

[0023] Adhesion. The samples are usually tested according to FINAT method No. 2, characterizing the adhesive peel strength from stainless steel ("SS"), glass or high density polyethylene ("HDPE") plates at a 90° peel angle after a dwell time of 20 minutes and 24 hours. All measurements are usually carried out at climatized room temperature 23°C ± 2°C and 50% RH ± 5% RH. FINAT (Féderation Internationaledes fabricants et transformateurs d'Adhésifs et Thermocollants) is the European association of the self-adhesive label industry (Laan van Nieuw-Oost 131-G, 2593BM The Hague, POBox 85612, 2508CH The Hague, The Netherlands).

[0024] Coating weight. Adhesive coating weight is expressed as the weight of dry adhesive on a standard area of ​​material in grams per square meter (gsm or g / m 2 ) meter. In product assembly, an appropriate amount of emulsion-based adhesive (liquid stage) is coated on a pre-siliconized carrier (called liner) and dried at 105°C for 2 minutes to remove water from the wet adhesive dispersion. An 18 gsm dry adhesive sample film is prepared in this way and then laminated to a label facestock (film or paper).

[0025] Cohesion / shear. To measure the cohesive strength of the adhesive, FINAT Test Method No. 8 was used, where a test sample of 1 inch x 1 inch size was applied to a stainless steel plate according to the method described in FINAT Test Method No. 8 and then exposed to a 1 kg hanging weight. The measurements were made on stainless steel plates, but other substrates such as glass may also be considered. The measurements were made at a climatized room temperature of 23°C ± 2°C and 50% RH ± 5% RH, and the sample cohesive failure was recorded in "hours".

[0026] Ring initial adhesion.Initial adhesion (adhesive tack) was characterized using standard FINAT method No. 9 when the adhesive was in contact with the substrate (glass, HDPE, SS). Testing was performed after conditioning the adhesive coated laminate in a controlled environment (23°C ± 2°C and 50% RH ± 5% RH relative humidity) for at least 4 hours. A 2.54 cm (1 inch) wide strip was cut and folded to form a loop, exposing the adhesive side. It was then placed on the INSTRON (TM) The adhesive was then pulled apart and the peak force to pull the adhesive away from the substrate was recorded. DETAILED DESCRIPTION

[0027] The present disclosure provides an article. In one embodiment, the article includes a first substrate and an adhesive layer in contact with the first substrate. The adhesive layer contains an adhesive composition. The adhesive composition comprises (i) an acrylic polymer composed of the following polymerized units: (a) a first monomer, the first monomer being an acrylic acid C4-C 18 The adhesive composition further comprises (ii) at least one inorganic neutralizing agent, and (iii) at least one surfactant. The article comprises a second substrate in contact with the adhesive layer.

[0028] The article comprises a first substrate. The first substrate can be a container (bottle, can, pouch, ampoule, jar, pot, box, bag, cup, vial, crate), film, tube, package, pipe, clothing, foil. The first substrate can be composed of or otherwise made from the following materials: metal (aluminum, copper, iron, gold, platinum, silver, steel, tin), wood (oak, pine, cedar, plywood, teak, mahogany, walnut, maple, oak, spruce, elm, rosewood, hickory, birch), glass (acrylic glass, borosilicate glass, lead glass), fabric (cotton, staple fiber, polyester nonwoven, vinyl or nonwoven, silk, wool), foam (polyurethane foam, polyethylene foam), plastic (polyamide, polycarbonate, polyolefin, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, polybutene, ethylene / α-olefin copolymer, polyolefin elastomer, polyethylene terephthalate, polybutylene terephthalate, polymethyl methacrylate, polyvinyl chloride, acrylonitrile-butadiene-styrene, polyester, polystyrene), paper material (paperboard), and any combination thereof.

[0029] The article of the present invention includes a second substrate. The second substrate may be composed of or otherwise made of plastics (polymethyl methacrylate, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, acrylonitrile-butadiene-styrene, polycarbonate, polyester, polystyrene), cellulose-based materials (paper, kraft paper, crepe paper, Japanese paper, paperboard, siliconized paper, parchment), fluorocarbon polymers (polytetrafluoroethylene, polytrifluorochloroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer), polyolefins (low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, polybutene, ethylene / α-olefin copolymer, polyolefin elastomer), fabrics (nonwoven fabrics, woven fabrics) and any combination thereof. In one embodiment, the second substrate is a face stock (interchangeably referred to as a "label face stock") composed of one or more of the foregoing materials.

[0030] In one embodiment, the second substrate is a label facestock. The label facestock can be paper, synthetic paper (synthetic paper made of one or more plastics disclosed in the above paragraphs). In another embodiment, the label facestock is a synthetic paper with fillers (calcium carbonate, titanium dioxide, clay, etc.). One or both sides of the label facestock can be treated with a primer layer and / or a surface modification treatment (corona treatment, radiation treatment) to improve adhesive anchoring, print anchoring or its barrier properties.

[0031] In one embodiment, the first substrate is a plastic container or a plastic film and the second substrate is a label facestock. In another embodiment, the first substrate is a plastic container and the second substrate is a paper label.

[0032] The article includes an adhesive layer having an adhesive composition comprising an acrylic polymer composed of the following polymerized units: (a) a first acrylic acid-based monomer, the first acrylic acid-based monomer being an acrylic acid C4-C 18 (b) a second acrylic acid-based monomer selected from acrylic acid, methacrylic acid, a C1-C3 alkyl acrylate optionally containing a hydroxyl group, and a combination thereof. Suitable acrylic acid C4-C 18 Non-limiting examples of alkyl esters include butyl acrylate (BA), butyl methacrylate, 2-ethylhexyl acrylate (2-EHA), octyl acrylate, isooctyl methacrylate, decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, pentadecyl methacrylate, and octadecyl methacrylate.

[0033] Non-limiting examples of suitable C1-C3 alkyl acrylates optionally containing hydroxyl groups include methyl acrylate, ethyl acrylate, propyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0034] In one embodiment, the acrylic polymer contains no olefin monomers. Non-limiting examples of olefin monomers (excluded from the acrylic polymer) include ethylene, propylene, 1,3-butadiene, pentene, hexene, octene, styrene, and 5-ethylidene-2-norbornene.

[0035] In one embodiment, the acrylic polymer is free of vinyl chloride monomers.

[0036] In one embodiment, the acrylic polymer contains a third acrylic acid-based monomer having a carboxylic acid functional group. Non-limiting examples of the third monomer include acrylic acid, methacrylic acid, and itaconic acid. In one embodiment, the acrylic polymer is a 2-ethylhexyl acrylate / ethyl acrylate / acrylic acid terpolymer.

[0037] In one embodiment, the acrylic polymer contains: (i) 50 wt % to 90 wt %, 60 wt % to 80 wt %, 65 wt % to 75 wt %, or 50 wt % to 71 wt % of a first monomer, based on the total weight of the acrylic polymer, wherein the first monomer is an acrylic acid C4-C 18 alkyl esters, (ii) 20 wt % to 50 wt %, greater than 20 wt % to 40 wt % or 25 wt % to 40 wt % of a second monomer selected from acrylic acid, methacrylic acid and optionally a hydroxyl-containing C1-C3 alkyl acrylate, and optionally (iii) 0.5 wt % to 20 wt %, 1 wt % to 10 wt % or 1 wt % to 5 wt % of a third monomer having a carboxylic acid functional group.

[0038] In addition to the acrylic polymer, the adhesive composition of the adhesive layer includes at least one inorganic neutralizing agent. The term "neutralizing agent" refers to a basic substance that can react with an acidic substance in an acid-base reaction. The term "inorganic neutralizing agent" refers to a neutralizing agent composed of a metal cation and a basic anion. Non-limiting examples of metal cations include cations of alkali metals (Group I of the periodic table) and alkaline earth metals (Group II of the periodic table), such as Li + 、Na + , K + , Cs + Mg 2+ and Ca 2+ Non-limiting examples of basic anions include hydroxide (OH - ). Non-limiting examples of suitable inorganic neutralizing agents include sodium hydroxide, potassium hydroxide, lithium hydroxide.

[0039] In one embodiment, the at least one inorganic neutralizing agent is sodium hydroxide.

[0040] In one embodiment, the inorganic neutralizing agent does not include an organic amine, or does not contain an amino group. In other words, the inorganic neutralizing agent does not include or contain a nitrogen atom (N).

[0041] The adhesive composition of the adhesive layer includes at least one surfactant. The surfactant may be a fatty alcohol ether sulfate. In one embodiment, the fatty alcohol ether sulfate includes C 12 -C 14 Sodium salt of fatty alcohol ether sulfate. Commercially available examples of suitable surfactants include, but are not limited to FES 77 (containing sodium ethoxylated lauryl ether sulfate), FES 32 (containing sodium salt of fatty alcohol polyglycol ether sulfate), FES 993 (containing sodium salt of fatty alcohol polyglycol ether sulfate) and FES 61 (containing sodium salt of fatty alcohol polyglycol ether sulfate), each of which are available from BASF, and / or Abex 18S (containing sodium salt of ethoxylated sulfated alcohol), which is available from Solvay.

[0042] In one embodiment, the adhesive composition contains other surfactants. Non-limiting examples of suitable additional surfactants include sodium dioctyl sulfosuccinate and acetylenic glycol ethylene oxide / propylene oxide adduct surfactants.

[0043] Commercially available sodium dioctyl sulfosuccinate surfactants include In one embodiment, the adhesive composition contains 0.1 wt % to 3 wt %, or 0.2 wt % to 1.5 wt %, or 0.2 wt % to 1 wt % of the dioctyl sodium sulfosuccinate surfactant, based on the total weight of the adhesive composition.

[0044] Commercially available acetylenic diol ethylene oxide / propylene oxide adduct surfactants include, but are not limited to

[0045] and The adhesive composition contains 0 wt%, 0.05 wt% to 1.5 wt%, or 0.1 wt% to 1 wt%, or 0.1 wt% to 0.5 wt% of an acetylene glycol ethylene oxide / propylene oxide adduct surfactant, based on the total weight of the adhesive composition. In one embodiment, the acetylene glycol ethylene oxide / propylene oxide adduct surfactant can be replaced or combined with a nonionic branched secondary alcohol ethoxylate surfactant. Non-limiting examples of suitable nonionic branched secondary alcohol ethoxylate surfactants include TERGITOL TMTMN-10.

[0046] In one embodiment, the adhesive composition optionally contains water.

[0047] In one embodiment, the adhesive composition optionally contains a defoamer. Commercially available defoamers include, but are not limited to, Tego Antifoam 2291, Foamaster MO S090, Tego Antifoam KS 53, Tego Antifoam 2450, Tego Antifoam D 2315, BYK 011.

[0048] Other additives that can be added to the adhesive composition include one or more water-soluble additives that can improve the wash-off performance of the adhesive layer. Non-limiting examples of water-soluble additives include synthetic water-soluble polymers such as polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP), poly (vinyl alcohol) (PVOH), polyacrylic acid (PAA), polyacrylamide, N- (2-hydroxypropyl) methacrylamide (HPMA), divinyl ether-maleic anhydride (DIVEMA), polyoxazoline, polyphosphate, polyphosphazene; natural water-soluble polymers such as xanthan gum, pectin, chitosan derivatives, dextran, carrageenan, guar gum, cellulose ether, hyaluronic acid (HA), albumin, starch or starch-based derivatives, or combinations thereof. Non-limiting examples of water-soluble additives include PEG 400, PEG 600, PEG1000, PEG1450, PEG3350, PEG8000, PVP K60 and PVP K90 with different molecular weights. In one embodiment, the adhesive composition comprises 0 wt%, 0.05 wt% to 20 wt%, or 0.25 wt% to 10 wt% of one or more additives based on the total weight of the adhesive composition.

[0049] Additionally, acid-containing cross-linked acrylic emulsion copolymers, such as alkali swellable acrylic emulsions (ASE), may be added to aid in the rheology and wash-off properties of the polymer. Acceptable additives include, but are not limited to, ACRYSOL TM ASE-60. In addition, rheology modifiers such as hydrophobically modified alkali swellable (HASE) associative thickeners may be added to aid in the rheology and wash-off properties of the polymer. Acceptable additives include, but are not limited to, ACRYSOL TM RM-7 and ACRYSOL TM RM-55.

[0050] In one embodiment, the adhesive composition is free or substantially free of one, some or all of the following: olefin monomers, crosslinking components, tackifiers, adipic acid dihydrazide (ADH), waxes, photocrosslinkable monomers, vinyl acetate, vinyl acetate derivatives, and any combination thereof.

[0051] In one embodiment, the adhesive composition forms an adhesive layer and comprises:

[0052] 80 wt % to 99 wt %, or 85 wt % to 99 wt %, or 90 wt % to 99 wt %, or 95 wt % to 99 wt %, based on the total weight of the adhesive composition, of an acrylic polymer;

[0053] 0.05 wt % to 5 wt %, or 0.5 wt % to 3 wt %, or 0.5 wt % to 1 wt % of at least one inorganic neutralizing agent, based on the total weight of the adhesive composition;

[0054] 0.1 wt % to 5 wt %, or 0.5 wt % to 3 wt %, or 1 wt % to 3 wt % of at least one surfactant, based on the total weight of the adhesive composition.

[0055] In one embodiment, the adhesive composition forms an adhesive layer and comprises:

[0056] (1) based on the total weight of the adhesive composition, 80 wt% to 99 wt%, or 85 wt% to 99 wt%, or 90 wt% to 99 wt%, or 95 wt% to 99 wt% of an acrylic polymer, the acrylic polymer being a 2-ethylhexyl acrylate / ethyl acrylate / acrylic acid terpolymer, the terpolymer consisting of:

[0057] (i) 50 wt% to 90 wt%, 60 wt% to 80 wt%, 65 wt% to 75 wt%, or 50 wt% to 71 wt% of 2-ethylhexyl acrylate monomer, based on the total weight of the terpolymer;

[0058] (ii) 20 wt% to 50 wt%, greater than 20 wt% to 40 wt%, or 25 wt% to 40 wt% of ethyl acrylate monomer, based on the total weight of the terpolymer; and

[0059] (iii) 0.5 wt % to 20 wt %, or 1 wt % to 10 wt %, or 1 wt % to 5 wt % of acrylic acid monomer, based on the total weight of the terpolymer;

[0060] (2) 0.05 wt % to 5 wt %, or 0.5 wt % to 3 wt %, or 0.5 wt % to 1 wt % of at least one inorganic neutralizing agent, based on the total weight of the adhesive composition, the inorganic neutralizing agent being sodium hydroxide; and

[0061] (3) based on the total weight of the adhesive composition, 0.1 wt % to 5 wt %, or 0.5 wt % to 3 wt %, or 1 wt % to 3 wt % of at least one surfactant, the surfactant being C 12 -C 14 Sodium salt of fatty alcohol ether sulfate; and the adhesive composition is in direct contact with the first substrate and the second substrate (label facestock) with a coating weight of 0.1 gsm to 50 gsm, or 5 gsm to 35 gsm, or 10 gsm to 20 gsm.

[0062] In one embodiment, at least one surface of the second substrate (label facestock) to which the adhesive layer is applied is subjected to a surface treatment comprising a primer coating. The primer coating comprises a hydrophilic or hydrophobic primer having a Tg above +10°C. Non-limiting examples of primers include PRIMAL TM TR-407、PRIMAL TM P-376LO. The primer coating forms a primer layer in direct contact with the second substrate and the adhesive layer at a coating weight of 0.01 grams per square meter (gsm), or 0.01 gsm to 5 gsm, 0.05 gsm to 4 gsm, 0.1 gsm to 3 gsm, or 1 gsm to 2 gsm.

[0063] In one embodiment, the structure of the article is first substrate / adhesive layer of the present invention / primer coating / second substrate. Alternatively, the structure of the article can be

[0064] A) First substrate / adhesive layer of the present invention / (optional standard adhesive layer) / primer coating / second substrate.

[0065] Each adhesive layer coating weight is from 0.1 gsm to 50 gsm, from 0.1 gsm to 50 gsm, or from 5 gsm to 35 gsm, or from 10 gsm to 20 gsm.

[0066] The present disclosure provides a method. The method includes providing a batch containing an article and a washing solution. The article includes a first substrate. The article also includes an adhesive layer in contact with the first substrate. The adhesive layer contains an adhesive composition. The adhesive composition includes (i) an acrylic polymer composed of the following polymerized units: (a) a first monomer, the first monomer being an acrylic acid C4-C 18The invention relates to a method for preparing an adhesive layer comprising: preparing an adhesive layer comprising: (a) an adhesive layer having a first monomer and a second monomer selected from the group consisting of acrylic acid, methacrylic acid and a C1-C3 alkyl acrylate optionally containing a hydroxyl group, (b) a second monomer selected from the group consisting of acrylic acid, methacrylic acid and a C1-C3 alkyl acrylate optionally containing a hydroxyl group, (ii) at least one inorganic neutralizing agent, and (iii) at least one surfactant. The article comprises a second substrate in contact with the adhesive layer. The wash solution of the batch comprises water, a surfactant and a base.

[0067] Non-limiting examples of surfactants that can be included in the wash solution include TRITON X 100, Tergitol 15-S-9, Tergitol 15-S-15, and Tergitol 15-S-12. In one embodiment, the surfactant in the wash solution includes a nonionic secondary alcohol ethoxylate surfactant. Non-limiting examples of suitable nonionic secondary alcohol ethoxylate surfactants include Tergitol 15-S-9.

[0068] In one embodiment, the wash solution contains 0 wt%, or 0.05 wt% to 5 wt%, or 0.1 wt% to 3 wt%, or 0.5 wt% to 1.5 wt% surfactant based on the total weight of the wash solution.

[0069] Non-limiting examples of bases suitable for use in the wash solution include NaOH and / or KOH. In one embodiment, the base in the wash solution is sodium hydroxide.

[0070] In one embodiment, the wash solution comprises 0.05 to 5 wt %, or 1 to 5 wt %, or 0.5 to 3 wt %, or 1 wt % or 2 wt % base based on the total weight of the wash solution.

[0071] In one embodiment, the wash solution comprises (i) water, (ii) 0 wt %, or 0.05 wt % to 5 wt %, or 0.1 wt % to 3 wt %, or 0.5 wt % to 1.5 wt % of a surfactant comprising a nonionic secondary alcohol ethoxylate, based on the total weight of the wash solution, and (iii) 0.05 wt % to 5 wt %, or 0.1 wt % to 5 wt %, or 0.5 wt % to 3 wt %, or 1 wt % to 2 wt % of a base which is sodium hydroxide, based on the total weight of the wash solution.

[0072] The method comprises contacting the article with a wash solution under conditions sufficient to separate the first substrate from the second substrate (ie, label facestock).

[0073] In one embodiment, the term "contact / contacting" refers to immersing the article in a washing solution. The term "under conditions sufficient to separate the first substrate from the second substrate" includes (i) introducing the batch material into a mixing device and (ii) stirring the batch material under conditions sufficient to separate the first substrate from the second substrate. The mixing device can mechanically stir the batch material, or the batch material can be manually stirred with a stirring rod. Non-limiting examples of suitable mixing devices include flasks, beakers, horizontal ribbon mixers, paddle mixers, tumble mixers, drum mixers, static mixers, planetary mixers, and premixers. Any of the aforementioned mixing devices may be equipped with suitable equipment to mix, stir, blend, rotate and / or stir the contents therein. The mixing device mixes the article with the washing solution and completely contacts the adhesive layer with the washing solution.

[0074] The terms "agitate" or "agitating" refer to the motion of mixing, blending, rotating, tumbling, shaking and / or stirring the article in the wash solution.

[0075] The term "conditions sufficient to separate the first substrate from the second substrate" also includes operating parameters that promote swelling and peeling of the adhesive layer. In one embodiment, the conditions include (i) the stirring speed of the mixture comprising the article and the washing solution (interchangeably referred to as the "batch"), (ii) the temperature of the washing solution, and (iii) the pH of the washing solution.

[0076] In one embodiment, the conditions sufficient to separate the first substrate from the second substrate include one, some, or all of the following parameters:

[0077] (i) agitating the article immersed in the washing solution at a rate of 50 rpm to 1000 rpm, or 100 rpm to 600 rpm, or 100 rpm to 500 rpm; and / or

[0078] (ii) heating the washing solution to 30°C to 65°C, 30°C to 55°C, 35°C to 55°C,

[0079] a temperature between 35°C and 45°C; and / or

[0080] (iii) adjusting the pH of the wash solution to 7 to 14 or 10 to 14.

[0081] Without being bound by a particular theory, it is believed that the washing solution swells the adhesive composition, allowing some or all of the adhesive composition to cleanly detach from and leave the first substrate. The term "separate" or "separating" refers to removing some or all of the adhesive layer (and the accompanying second substrate) from the first substrate.

[0082] In one embodiment, the method further comprises removing the first substrate (having little or no adhesive layer) from the wash solution and rinsing the first substrate with water prior to the further recycling step. In this manner, the label facestock and adhesive composition are removed from the first substrate.

[0083] In one embodiment, the method comprises:

[0084] (1) providing a batch comprising a product and a washing solution, the product comprising

[0085] A. The first substrate and

[0086] B. an adhesive layer in contact with the first substrate, the adhesive layer comprising an adhesive composition, the adhesive composition comprising

[0087] (i) based on the total weight of the adhesive composition, 80 wt % to 99 wt %, or 85 wt % to 99 wt %, or 90 wt % to 99 wt %, or 95 wt % to 99 wt % of an acrylic polymer comprising the following polymerized units:

[0088] (a) 50 wt % to 90 wt %, 60 wt % to 80 wt %, 65 wt % to 75 wt % based on the total weight of the acrylic polymer

[0089] or 50 wt % to 71 wt % of a first monomer, the first monomer being acrylic acid C4-C 18 Alkyl esters; and

[0090] (b) 20 to 50 wt%, greater than 20 to 40 wt%, or 25 to 40 wt%, based on the total weight of the acrylic polymer, of a second monomer selected from the group consisting of C1-C3 alkyl acrylates optionally containing hydroxyl groups, acrylic acid, and methacrylic acid; and

[0091] (c) 0.5 wt % to 20 wt %, 1 wt % to 10 wt %, or 1 wt % to 5 wt % of a third monomer having a carboxylic acid functional group, based on the total weight of the acrylic polymer;

[0092] (ii) 0.05 wt % to 5 wt %, or 0.5 wt % to 3 wt %, or 0.5 wt % to 1 wt % of at least one inorganic neutralizing agent, based on the total weight of the adhesive composition; and

[0093] (iii) 0.1 wt % to 5 wt %, or 0.5 wt % to 3 wt %, or 1 wt % to 3 wt % of at least one surfactant, based on the total weight of the adhesive composition.

[0094] C. a second substrate in contact with the adhesive layer; and

[0095] A washing solution comprising

[0096] (i) water,

[0097] (ii) 0 wt %, or 0.05 wt % to 5 wt %, or 0.1 wt % to 3 wt %, or 0.5 wt % to 1 wt % of a surfactant, based on the total weight of the wash solution, and

[0098] (iii) 0.05 wt % to 5 wt %, or 0.5 wt % to 3 wt %, or 1 wt % to 2 wt % of a base, based on the total weight of the wash solution; and

[0099] (2) immersing the article in the cleaning solution;

[0100] (3) agitating the article and the wash solution under conditions sufficient to separate the first substrate from the second substrate; and

[0101] (4) Removing the second substrate from the first substrate.

[0102] The method is implemented in which a dense first substrate such as PET (PET bottle) will sink, while a light second substrate (such as label PP) will float, so that the first substrate can be separated from the second substrate by a filtering process, whereby the floating light second substrate (label face stock) and the settled dense first substrate (PET bottle) are separated from each other. (A filter, a filter or a skimming method can be used). In one embodiment, the first substrate has a particle size of greater than 1 g / cm 3 To less than 3g / cm 3 The second substrate has a density greater than 0.01 g / cm 3 To less than 1g / cm 3 density and floats on the surface of the washing solution.

[0103] In one embodiment, the first substrate is separated from the second substrate by a sinking and floating mechanism. This sinking and floating mechanism takes advantage of the density difference between the first substrate (bottle) and the label facestock (second substrate).

[0104] In one embodiment, the first substrate has a thickness of less than 1 g / cm 3 Non-limiting examples include HDPE bottles, which will float on the surface of the washing solution, and the second substrate has a density greater than 1 g / cm 3 In this case, the first substrate (HDPE) will float, while the second substrate (alkali-resistant paper) will sink to the bottom of the washing solution.

[0105] In one embodiment, the first substrate is separated from the second substrate by a settling and flotation mechanism. This settling and flotation mechanism takes advantage of the density difference between the first substrate and the label system (second substrate). In some cases, the paper label may be dispersed in small fibers, which will float or sink based on the composition of the paper label, and they will have to be filtered out of the system.

[0106] In one embodiment, the second substrate is a paper label that disintegrates and disperses into a wash solution into smaller particles under conditions sufficient to separate the first substrate from the second substrate. In one embodiment, the separation comprises filtering the first substrate from the wash solution with a filter (mesh filter).

[0107] By way of example and not limitation, some embodiments of the present disclosure will now be described in detail in the following examples.

[0108] Example

[0109] 1. Materials

[0110] The materials used in the inventive examples ("IE") and comparative samples ("CS") are provided in Table 1 below.

[0111] Table 1

[0112]

[0113]

[0114] A. Synthesis of Acrylic Polymers in Adhesive Compositions of IE1 and IE2

[0115] A monomer emulsion containing 86.31 wt% of a monomer mixture was prepared by mixing: (i) a monomer composition containing 71 wt% of a first monomer, 2-ethylhexyl acrylate, 26 wt% of a second monomer, ethyl acrylate, and 3 wt% of a third monomer, acrylic acid, based on the total weight of the first, second, and third monomers, (ii) sodium dodecylbenzene sulfonate (branched), (iii) Aerosol A-102, and (iv) a small amount of sodium hydroxide (monomer emulsion buffer). The wt% is based on the total weight of the polymer batch / emulsion.

[0116] With the reactor water maintained at 90-92°C, 0.054 wt% of the total batch of sodium carbonate and 0.312 wt% of a solution of sodium persulfate in water were added to the reactor.

[0117] 0.22 wt% of the polymer latex with seeds of 250 nm diameter was added to the kettle and held for two minutes, followed by the addition of 0.13 wt% of the second polymer latex with seeds of 100 nm diameter.

[0118] With the reactor at 83 °C, a step-addition thermal polymerization was conducted by feeding the monomer emulsion into the reactor over 150 minutes along with a co-feed of sodium persulfate (0.23 wt%) while maintaining the reactor temperature between 85 and 87 °C.

[0119] After adding 60 wt% of the monomer emulsion feed, 0.26 wt% of a polymer latex having seeds with diameters <50 nm was added to the reactor to produce a third smaller particle size polymer mode.

[0120] While at about 84°C, a chase redox pair of 0.16 wt% tert-butyl hydroperoxide and 0.064 wt% D(-)-isoascorbic acid co-feed reagents were fed to the reactor over 45 minutes to reduce residual monomer levels to final specifications.

[0121] The reaction was adjusted to a pH of 4 to 4.5 by ammonium hydroxide at a temperature of 55° C. or less to produce an acrylic polymer containing 71 wt % 2-EHA, 26 wt % EA and 3 wt % AA based on the total weight of the acrylic polymer.

[0122] The post-addition solution containing 0.26 wt % Surfynol 440, 1.21 wt % Disponil Fes 77 and 0.42 wt % Aerosol OT-75 (weight percentages based on the total weight of the adhesive composition) was added to the acrylic polymer in the kettle over 30 minutes while cooling to 40-45°C.

[0123] At a temperature below 45°C, an inorganic neutralizer (10 wt% sodium hydroxide in water) was added until the latex pH reached 8 to 8.5. After 15 minutes, the biocide package was added and the final solids were 57.5% to 58.5%.

[0124] The obtained adhesive composition was filtered through a 100-mesh bag and filled.

[0125] C. Preparation of Labels

[0126] Coated Sample 1 (paper label) and Coated Sample 2 (film label) were coated with the adhesive composition of the present invention and evaluated for adhesive wash performance, adhesion level, tack, and shear properties. The method used to prepare each sample is provided below.

[0127] Coating sample 1 (paper label assembly)

[0128] Use hydrophilic primer PRIMAL TM TR-407 was directly coated on one side of 80 gsm MOSAICO paper and dried at 70°C for 3 minutes to obtain a final primer coating weight of 2 gsm to prepare the paper facestock. The adhesive dispersion was prepared (formulated), conditioned for 24 hours before application, and then directly coated on the pre-siliconized paper liner. The wet adhesive-coated pre-siliconized paper liner was then dried at 105°C for 2 minutes to obtain a dry new adhesive layer of 18 gsm to prepare the adhesive layer. PRIMAL was coated at 40°C / 40 psi. (TM) TR-407 coated paper was laminated to the dry adhesive layer.

[0129] Coating sample 2 (film label assembly)

[0130] Use hydrophilic primer PRIMAL TM TR-407 was coated on one side of an oriented polypropylene film (OPP) at a coating weight of 2 gsm, followed by drying at 70°C for 3 minutes to prepare the film facestock. The adhesive dispersion was prepared (formulated), conditioned for 24 hours before application, and then directly coated on a pre-siliconized paper liner. The wet adhesive-coated pre-siliconized paper liner was then dried at 105°C for 2 minutes to obtain an 18 gsm dry novel adhesive layer to prepare the adhesive layer. PRIMAL was then laminated at 40°C / 40 psi. (TM) The TR-407 coated paper side was laminated with a dry adhesive layer. The adhesion, loop tack and shear resistance test results for Coated Sample 1 and Coated Sample 2 are shown in Table 2 below.

[0131] Table 2

[0132] Glass panel testing Coating sample 1 (IE 1) Coating sample 2 (CS1) 90° peel adhesion 20 minutes dwell time (N / inch) 4.7("A”)* 5.5("A”) 90° peel adhesion 24 hours dwell time (N / inch) 7.2("PT")* 7.2("A”) <![CDATA[Ring tack (N / inch 2 )]]> 9.3("A”) 8.3("A”) Shear resistance (hours) >20 >20

[0133] *“A” stands for “Adhesion Failure”

[0134] *“PT” stands for “Paper Tear”

[0135] The measured data depicts that the PSA properties of the inventive articles and / or inventive adhesive compositions shown in Table 2 are within the acceptable performance range required for non-washable adhesives in the market. The inventive adhesive compositions exhibit similar or better performance during use, but have the additional benefit of being removable (or washable) under the aforementioned conditions, thereby allowing the substrate to which they are attached to be recycled.

[0136] D. Preparation of IE1 (PET / adhesive / Mospaper)

[0137] A pre-prepared paper label with 80 gsm MOSAICO paper (coating sample 1) was manually applied to the sidewall of the PET bottle, with light pressure from the thumb to eliminate air bubbles. The labeled PET bottles were then stored in a CTR for 4 days before being cut into small pieces (1×1 cm) for washing tests. The label size was a strip of approximately 6 cm wide and 10 cm long.

[0138] E. Comparison of the preparation of CS1 (PET / adhesive / BOPP)

[0139] A previously prepared oriented polypropylene film (OPP) label (Coating Sample 2) with a 48 μm thick (43.7 gsm basis weight) oriented polypropylene film was manually applied to the sidewall of the PET bottle, with light pressure from the thumb to eliminate air bubbles. The labeled PET bottles were then stored in a CTR for 4 days before being cut into small pieces (1×1 cm) for wash testing. The label size was a strip of approximately 6 cm wide and 10 cm long.

[0140] F. Washing procedures and results

[0141] Use 20 mL of 1 wt% NaOH and 0.5 wt% Tergitol in water TM After the wash solution was prepared and added to the beaker, the temperature of the wash solution was raised to the corresponding temperature to be tested (ie, 35°C, 45°C, or 55°C) and maintained at that temperature until the wash was completed.

[0142] 20 1 cm x 1 cm IE1 flakes were added to a beaker and immersed in the heated wash solution. The beaker was equipped with a 4 cm magnetic stirrer to impart a mixing speed of 350 rpm and stir the flakes in the wash solution. The time taken for the recording paper label (coated sample 1) to be completely peeled off the PET substrate is shown in Table 3.

[0143] Table 3

[0144]

[0145] As shown in Table 3, at wash solution temperatures ranging from 35°C to 55°C, the paper substrate was completely released from the PET substrate within 5 minutes.

[0146] It is particularly intended that the present disclosure is not limited to the embodiments and descriptions contained herein, but includes modifications of those embodiments including parts of the embodiments and combinations of elements of different embodiments as appear within the scope of the following claims.

Claims

1. A product comprising: A. a first substrate; as well as B. an adhesive layer in contact with the first substrate, the adhesive layer comprising an adhesive composition, the adhesive composition comprising (i) an acrylic acid polymer comprising the following polymerized units: (a) a first monomer, wherein the first monomer is acrylic acid C4-C 18 Alkyl esters; and (b) a second monomer selected from the group consisting of acrylic acid, methacrylic acid and C1-C3 alkyl acrylates optionally containing a hydroxyl group; (ii) at least one inorganic neutralizing agent; and (iii) at least one surfactant; and C. A second substrate in contact with the adhesive layer.

2. The article according to claim 1, comprising (D) A primer layer located between the adhesive layer and the second substrate.

3. The article according to any one of claims 1 to 2, wherein the acrylic acid C4-C 18 The alkyl ester is selected from the group consisting of butyl acrylate, butyl methacrylate, ethylhexyl acrylate, octyl acrylate, isooctyl methacrylate, decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, pentadecyl methacrylate, and octadecyl methacrylate.

4. The article according to any one of claims 1 to 3, wherein the C1-C3 alkyl acrylate optionally containing a hydroxyl group is selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate.

5. The article of any one of claims 1 to 4, wherein the acrylic polymer is a 2-ethylhexyl acrylate / ethyl acrylate / acrylic acid terpolymer.

6. The article according to any one of claims 1 to 5, wherein the terpolymer comprises, based on the total weight of the terpolymer: (i) 50% to 71% by weight of ethylhexyl acrylate; (ii) 25 to 40 wt. % of ethyl acrylate, and (iii) 1 to 10 wt% of acrylic acid.

7. The article of any one of claims 1 to 6, wherein the at least one inorganic neutralizing agent is sodium hydroxide.

8. The article of any one of claims 1 to 7, wherein the at least one surfactant comprises a fatty alcohol ether sulfate.

9. The article according to any one of claims 1 to 8, wherein the adhesive composition comprises, based on the total weight of the adhesive composition: 80 to 99 wt % of said acrylic polymer; 0.05 wt % to 5 wt % of the at least one inorganic neutralizing agent; and 0.1 wt. % to 5 wt. % of the at least one surfactant.

10. The article of any one of claims 1 to 9, wherein the first substrate is selected from the group consisting of a plastic container and a plastic film, and the second substrate is a label.

11. A method comprising: (1) providing a batch comprising an article and a washing solution, The product comprises A. a first substrate; as well as B. an adhesive layer in contact with the first substrate, the adhesive layer comprising an adhesive composition, the adhesive composition comprising (i) an acrylic acid polymer comprising the following polymerized units: (a) a first monomer, wherein the first monomer is acrylic acid C4-C 18 Alkyl esters; and (b) a second monomer selected from the group consisting of acrylic acid, methacrylic acid and C1-C3 alkyl acrylates optionally containing a hydroxyl group; (ii) at least one inorganic neutralizing agent; as well as (iii) at least one surfactant; and C. a second substrate in contact with the adhesive layer; and The washing solution comprises water, a surfactant and an alkali; (2) contacting the article with the wash solution under conditions sufficient to separate the first substrate from the second substrate.

12. The method of claim 11, wherein the contacting step comprises immersing the article in the wash solution and agitating the article and the wash solution at a temperature below 65°C.

13. The process according to claim 11 or 12, wherein the base is sodium hydroxide.

14. The method of any one of claims 11 to 13, wherein the surfactant comprises a nonionic secondary alcohol ethoxylate.

15. The method of any one of claims 11 to 14, wherein the scrubbing solution has 0.1 wt% to 5 wt% of the base, based on the total weight of the scrubbing solution.

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