Water-dispersible hot-melt adhesives and use thereof

Abstract

The present disclosure relates to water-dispersible low-application-temperature hot melt adhesives comprising a sulfopolyester, a plasticizer, and a tackifier. The adhesives exhibit extended open times and high initial tack strength, and can be used in a variety of applications, including the manufacture of paper products and other products that can be recycled.

Description

Technical Field

[0001] This invention relates to a hot melt adhesive with low water dispersibility and application temperature. In some embodiments, the hot melt adhesive comprises a sulfonated polyester, a plasticizer (e.g., polyethylene glycol), and a tackifier (e.g., optionally modified rosin ester). The adhesive exhibits extended open time and high initial tack strength and can be used in a variety of applications, including the preparation of paper products and other recyclable products. Background Technology

[0002] In paper production, sheet transfer is a crucial step in the process of winding sheet webs from the paper production line onto an empty reel. The process of replacing a full roll of paper with an empty reel is called a turnup. During turnup, adhesives are used to attach the sheet webs from the paper production line to the empty reel, and winding begins to produce rolls for downstream paper operations. In downstream operations, the full rolls are processed into smaller rolls and packaged for consumer use. See, for example, U.S. Publication No. 2020 / 0039777.

[0003] Currently, both water-based adhesives and pressure-sensitive adhesives are used during roll changeovers. However, each type of adhesive has significant drawbacks. Water-based adhesives suffer from adhesive splattering and a lack of initial tack strength during roll changeovers. While water-based adhesives have varying viscosities at room temperature, ranging from being as fluid as water (1 centipoise) to greater than 20,000 cPs, they lack cohesive strength when applied, even at viscosities greater than 20,000 cPs, because it takes time for the water in the adhesive to evaporate and build up cohesive strength. This leads to slinging and splashing during roll changeovers (centrifugal force throws the water-based adhesive onto the equipment and surrounding area due to inappropriate viscosity and roll speed) and shop floor cleanup issues (requiring cleaning of the rolls and other parts of the equipment).

[0004] Although pressure-sensitive adhesives do not cause splashing during roll changes, and the strength they provide allows the paper to latch onto the empty roll, their amorphous and hydrophobic properties make recycling difficult. The inability to effectively remove these synthetic contaminants hinders increased waste paper recycling.

[0005] U.S. Patent Nos. 5,098,962 and 6,162,890 and European Patent No. EP1,268,701 describe water-dispersible hot melt adhesive compositions.

[0006] However, there remains a need for new hot melt adhesives that not only exhibit good open time and initial tack strength but are also water-dispersible and thus environmentally friendly. This invention addresses these needs and produces a hot melt adhesive with a low application temperature that allows for the recycling of unprocessed paper during roll-over processes without splashing or contamination from adhesive residues. Summary of the Invention

[0007] The inventors have unexpectedly developed a hot melt adhesive that not only exhibits good open time and initial tack strength, but is also water-dispersible and thus environmentally friendly during, for example, rewinding processes in paper production. Because the adhesive described herein is dispersible in water, recyclable paper fibers can be reused in the paper production process during paper recycling without contamination from residual adhesive. Furthermore, the hot melt adhesive described herein provides sufficient bond strength for paper rewinding processes even after long open times.

[0008] This invention addresses the challenges posed by using water-based or pressure-sensitive adhesives by increasing the viscosity of the adhesive to minimize splashing and providing sufficient adhesive strength similar to that of pressure-sensitive adhesives, while possessing the long open time characteristics of both water-based and pressure-sensitive adhesives. It also provides water-dispersible properties to the adhesive's performance to significantly reduce waste and improve the recyclability of unprocessable paper generated during the manufacturing process.

[0009] The hot melt adhesive described herein can be used in paper roll changing processes, as well as in tissue and towel applications (e.g., core winding, lamination, tissue pick-up and tail sealing), and in paper bag applications.

[0010] In one aspect, the present invention relates to a water-dispersible hot melt adhesive, the water-dispersible hot melt adhesive comprising: (a) Water-dispersible polymers (e.g., sulfonated polyesters); (b) Tackifiers (e.g., tackifiers based on optionally modified resins); (c) Plasticizers; and (d) Any available antioxidants; The hot melt adhesive mentioned above: (i) It has an open time of at least about 4 weeks, wherein the initial loop tack value is about 3 to about 15 ounces of force per 0.125 square inches when measured according to ASTM D6195-03, and remains within the range for about 3 weeks; (ii) When measured according to TAPPI UM666, it has a water dispersibility of greater than about 80% (e.g., greater than about 90% or greater than about 95%); or (iii) Both (i) and (ii).

[0011] In any embodiment of the hot melt adhesive described herein, the hot melt adhesive: (i) Has an open period of at least about one week; wherein, when measured according to ASTM D6195-03, the initial tack value is about 3 to about 15 ounces of force per 0.125 square inches and remains within said range for about one week; and (iii) When measured according to TAPPI UM666, it has a water dispersibility of more than about 80% (e.g., more than about 90% or more than about 95%).

[0012] In some embodiments of any of the hot melt adhesives described herein, the water-dispersible polymer (e.g., sulfonated polyester) has: (i) Glass transition temperature (T0) from about -20°C to about 65°C, for example from about 0°C to about 52°C g ); (ii) Melt viscosity of about 1,000 to about 150,000 cPs, for example about 5,000 to about 50,000 cPs (e.g., measured at 177°C); or (iii) Both (i) and (ii).

[0013] In some embodiments of any of the hot melt adhesives described herein, the tackifier comprises a polar tackifier, such as rosin, rosin ester, modified rosin ester, styrene-modified terpene resin, phenolic terpenesin, or any combination thereof.

[0014] In some embodiments of any of the hot melt adhesives described herein, the tackifier comprises optionally modified rosin esters. The modification process may include blending, grafting, and curing. Blending is generally described as a process of mixing two or more rosin esters together without causing a chemical reaction. Grafting is a process in which functional groups react with the backbone of the rosin ester via a Diels-Alder reaction, as described, for example, in Tirto Prakoso et al., 2021 IOP Conf. Ser.: Mater.Sci. Eng., 1143, 012071. Curing provides a crosslinked network with the functional groups in the network. Rosin esters modified by blending and grafting are particularly preferred tackifiers.

[0015] In some embodiments of any of the hot melt adhesives described herein, the tackifier includes modified rosin ester.

[0016] In some embodiments of any of the hot melt adhesives described herein, the tackifier comprises a modified rosin ester, wherein the rosin ester is modified with maleic anhydride, glycidyl methacrylate, butyl acrylate, methyl methacrylate, acrylic acid, vinyltrimethoxysilane, or any combination thereof.

[0017] In some embodiments of any of the hot melt adhesives described herein, the tackifier comprises maleic anhydride-modified rosin ester.

[0018] In some embodiments of any of the hot melt adhesives described herein, the tackifier includes styrene-modified terpene resins, terpene phenolic resins, or any combination thereof.

[0019] In certain embodiments of any of the hot melt adhesives described herein, the tackifier has: (i) An acid value of about 5 to about 100, for example, about 10 to about 80; (ii) A softening point from about 0°C to about 150°C, for example, from about 50°C to about 140°C; or (iii) Both (i) and (ii).

[0020] In certain embodiments of any of the hot melt adhesives described herein, the plasticizer includes polyalkylene glycols (e.g., polyethylene glycol, polypropylene glycol, polybutane glycol), esters (e.g., but not limited to, sebacic acid esters, adipic acid esters, terephthalic acid esters, dibenzoic acid esters, glutaric acid esters, phthalic acid esters, and azelaic acid esters, or combinations thereof), provided they are compatible with the other components in the hot melt adhesive. Compatibility refers to the ability to maintain a homogeneous solution without phase separation at both room temperature and elevated temperatures.

[0021] In some embodiments of any of the hot melt adhesives described herein, the plasticizer includes polyethylene glycol.

[0022] In some embodiments of any of the hot melt adhesives described herein, the plasticizer (e.g., polyethylene glycol) has a molecular weight of about 100 to about 10,000 Daltons, such as about 300 to about 3,000 Daltons, or about 300 to about 1,800 Daltons.

[0023] In some embodiments of any of the hot melt adhesives described herein, the plasticizer (e.g., polyethylene glycol) has a molecular weight of about 600. In some embodiments of any of the hot melt adhesives described herein, the plasticizer (e.g., polyethylene glycol) has a molecular weight of about 1450.

[0024] In some embodiments of any of the hot melt adhesives described herein, the adhesive comprises: (i) Water-dispersible polymers (e.g., sulfonated polyesters) of about 5% w / w to about 90% w / w, such as about 30% w / w to about 80% w / w, about 45% w / w to about 75% w / w. (ii) Plasticizers (e.g., polyethylene glycol) of about 5% w / w to about 90% w / w, such as about 10% w / w to about 50% w / w, about 15% w / w to about 30% w / w. (iii) a tackifier of about 3% w / w to about 90% w / w, such as about 5% w / w to about 30% w / w, or about 10% w / w to about 15% w / w (e.g., optionally modified rosin ester); or (iv) Any combination of (i), (ii) and (iii).

[0025] In some embodiments of any of the hot melt adhesives described herein: (i) Water-dispersible polymers include sulfonated polyesters; (ii) Plasticizers include polyethylene glycol; (iii) The tackifier includes, optionally, modified rosin esters; or (iv) Any combination of (i), (ii) and (iii).

[0026] In some embodiments, the open time of any of the hot melt adhesives described herein is at least about 1 hour, for example at least about 1 day, at least about 2 days, at least about 3 days, at least about 4 days, at least about 5 days, at least about 6 days, at least about 7 days, at least about 14 days, or at least about 21 days. Open time is the time after adhesive application during which operable bonding can be achieved, and this is associated with a ring initial tack test. Initial ring initial tack measurements are performed to evaluate the hot melt adhesives and then daily, and when they remain within acceptable limits, they are considered to have an open time of that duration. For hot melt adhesives, a long open time is desirable.

[0027] In another embodiment, the open time of any of the hot melt adhesives described herein is at least about 7 days, for example at least about 8 days, at least about 9 days, at least about 10 days, at least about 11 days, at least about 12 days, at least about 13 days, at least about 14 days, or at least about 21 days.

[0028] In another embodiment, when measured, for example, according to ASTM D6195-03, the ring initial tack value of any of the hot melt adhesives described herein is about 3 to about 15, for example, about 4 to about 7 ounces of force per 0.125 square inches.

[0029] In another embodiment, when measured, for example, according to ASTM D6195-03, the ring initial tack value of any of the hot melt adhesives described herein is greater than about 3, for example greater than about 4 or greater than about 5 ounces of force per 0.125 square inches.

[0030] In another embodiment, when measured, for example, according to ASTM D6195-03, the ring initial tack value of any of the hot melt adhesives described herein is less than about 15, for example less than about 12 or less than about 10 ounces of force per 0.125 square inches.

[0031] In another embodiment, when measured, for example, according to ASTM D6195-03, the ring initial tack value of any of the hot melt adhesives described herein is greater than about 3, for example greater than about 4, and less than about 15, for example less than about 12 or less than about 11 ounces of force per 0.125 square inches.

[0032] In another embodiment, when measured, for example, according to ASTM D6195-03, the ring initial tack value of any of the hot melt adhesives described herein is less than about 15, for example less than about 12 or less than about 11 ounces of force per 0.125 square inches.

[0033] In some embodiments, when measured, for example, according to TAPPI UM666, the water dispersibility of any of the hot melt adhesives described herein is greater than about 80%, for example greater than about 81%, greater than about 82%, greater than about 83%, greater than about 84%, greater than about 85%, greater than about 86%, greater than about 87%, greater than about 88%, greater than about 89%, greater than about 90%, greater than about 91%, greater than about 92%, greater than about 93%, greater than about 94%, greater than about 95%, greater than about 96%, greater than about 97%, greater than about 98%, or greater than about 99%.

[0034] In another embodiment, when measured at 250°F, for example according to ASTM D3236, the viscosity of any of the hot melt adhesives described herein is about 1,000 cPs to about 20,000 cPs, for example about 1,500 cPs to about 18,000 cPs, or about 2,000 cPs to about 15,000 cPs.

[0035] In any embodiment of the hot melt adhesives described herein, the hot melt adhesive does not exhibit phase separation (e.g., remains homogeneous) during storage (e.g., stored for 2 days in a convection oven set to 320°F).

[0036] In some embodiments, any of the hot melt adhesives described herein can be applied to a substrate by spraying (e.g., nozzle spraying), brushing, gravity flow, printing (e.g., screen printing), roller coating, and other methods known in the art.

[0037] In another aspect, the present invention relates to articles comprising a hot melt adhesive as described in any of the embodiments described herein.

[0038] In some implementations, the articles are bags, tissues, paper towels, kitchen towels, toilet paper, industrial towels, notebooks, and post-it notes. ® ), or tape. Attached Figure Description

[0039] Figure 1 The initial values ​​at 320°F were shown (respectively). Figure 1 A and Figure 1 B) and formulations 21 and 22 of Example 8 after standing at 320°F for 48 hours (Figures 2A and 2B, respectively). Detailed Implementation

[0040] As used herein, the term "open time" refers to the time during which the adhesive remains open after being applied to a substrate and before a second substrate is placed onto the adhesive, and is still able to form an adhesive between the two substrates.

[0041] As used herein, the term “about” means, when referring to a number or range of values, that the number or range of values ​​in question is an approximation within experimental variability (or within statistical experimental error), and therefore the number or range of values ​​may deviate from, for example, the stated number or range of values ​​by 1% to 15%.

[0042] As used herein, the term "comprising" (and related terms such as "comprise / comprises" or "having" or "including") includes, but is not limited to, embodiments that are "consisting of" or "substantially composed of" the features, such as embodiments of any composition of a substance, composition, method, or process.

[0043] As used herein, the terms “paper towel” and “paper towel substrate” in one embodiment refer to commercially available absorbent disposable household paper towels made from wood pulp and primarily used for household cleaning.

[0044] All ranges disclosed herein include the listed endpoints and can be combined independently (e.g., a range of “2 to 10” includes endpoints 2 and 10 as well as all intermediate values). The endpoints of the ranges and any values ​​disclosed herein are not limited to precise ranges or values; they are not precise enough to include values ​​that approximate these ranges and / or values. As used herein, approximate language can be applied to modify any quantitative representation that may vary without altering its underlying function. Thus, in some cases, a value modified by one or more terms (such as “about”) may not be limited to the specified precise value. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value. The modifier “about” should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. For example, the expression “about 2 to about 4” also discloses the range “2 to 4”. The term “about” can refer to ±10% of the indicated number. For example, “about 10%” can represent a range of 9% to 11%, and “about 1” can mean 0.9 to 1.1. Other meanings of “about” can be apparent from the context (e.g., rounding), so “about 1” can also mean 0.5 to 1.4.

[0045] Water-dispersible polymers In some embodiments of any of the hot melt adhesives described herein, the water-dispersible polymer is a sulfonated polyester. Sulfonated polyesters suitable for use in the hot melt adhesives described herein are described, for example, in U.S. Patent Nos. 5,859,152 and 6,007,910 and U.S. Publication No. 2006 / 0058438 (each of which is hereby incorporated herein by reference in its entirety).

[0046] plasticizer Suitable plasticizers must be compatible with the other components in the hot melt adhesive and include monohydric or polyhydric alcohols, such as ethylene glycol monophenyl ether, hexanediol, glycerol, and especially polyalkylene glycols. Polyethylene glycol and its esterified or etherified derivatives are preferred. Polypropylene glycol, polybutanediol, and polymethylene glycol are also suitable.

[0047] Tackifier Rosin is a natural tackifier derived from pine tree byproducts (e.g., resin rosin, wood rosin, and tall oil rosin) with an acid value of up to 170. Rosin esters are derived from the esterification of rosin using various alcohols (e.g., glycerol, methanol, triethylene glycol, and pentaerythritol). Styrified terpenes and terpene phenolic resins are polar resins due to the presence of aromatic styrene and phenolic hydroxyl groups, respectively.

[0048] In some embodiments, the tackifying resins used in any of the water-dispersible hot melt adhesives described herein include any compatible resins or mixtures thereof, such as: (1) natural rosin and modified rosin, such as rosin resin, wood rosin, tall oil rosin, distilled rosin, hydrogenated rosin, dimer rosin, and polymerized rosin; (2) rosin esters, such as glycerol esters and pentaerythritol esters of natural rosin and modified rosin, such as glycerol esters of light-colored wood rosin, glycerol esters of hydrogenated rosin, glycerol esters of polymerized rosin, pentaerythritol esters of hydrogenated rosin, and phenolic modified pentaerythritol esters of rosin; and (3) phenolic modified (a) terpene resins or (b) α-methylstyrene resins and their hydrogenated derivatives, such as resin products produced by the condensation of bicyclic terpenes and phenols in an acidic medium. Mixtures of two or more of the above-described tackifying resins, and blends of the above-described resins with a small amount (e.g., less than about 20% of the adhesive) of less compatible resins, may be used in some formulations.

[0049] Non-limiting representative polar tackifiers also include: ionic materials, such as FORALNC available from Hercules; nonionic materials, such as FORAL AX, also from Hercules; α-methylstyrene phenolic resins, such as URATAK 68520 from DSM Resins; rosin esters, such as UNITAC R100L available from Union Camp; and terpene phenolic resins, such as NIREZ 300 available from Arizona Chemical.

[0050] In certain embodiments of any of the hot melt adhesives described herein, the tackifier comprises a modified rosin ester, wherein the rosin ester is modified with maleic anhydride, fumaric anhydride, glycidyl methacrylate, butyl acrylate, methyl methacrylate, acrylic acid, vinyltrimethoxysilane, or any combination thereof. In certain embodiments of any of the hot melt adhesives described herein, the tackifier comprises a maleic anhydride-modified rosin ester. In certain embodiments of any of the hot melt adhesives described herein, the tackifier comprises a fumaric anhydride-modified rosin ester.

[0051] Representative non-limiting modified rosin ester tackifiers include Teckros M105, Teckros 120, Teckros AF128, and Teckros AF160 from Teckrez.

[0052] In some embodiments of any of the hot melt adhesives described herein, the tackifier includes styrene-modified terpene resins, terpene phenolic resins, or any combination thereof.

[0053] antioxidants Suitable stabilizers or antioxidants included herein are high molecular weight hindered phenols and polyfunctional phenols (e.g., sulfur- and phosphorus-containing phenols). Hindered phenols are well known to those skilled in the art and can be characterized as phenolic compounds that also contain a spatially large group immediately adjacent to their phenolic hydroxyl group. In particular, the tert-butyl group is typically substituted onto the benzene ring at at least one ortho position relative to the phenolic hydroxyl group. The presence of these spatially large substituents near the hydroxyl group serves to delay its stretching frequency and, consequently, its reactivity; thus, this hindrance provides the phenolic compound with its stabilizing properties. Representative hindered phenols include, for example, 1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-benzene; pentaerythritol tetra-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; n-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 4,4'-methylenebis(2,6-tert-butylphenol); 4,4'-thiobis(6-tert-butyl-o-cresol); 2,6-di-tert-butylphenol; 6-(4-hydroxyphenoxy)-2,4-bis(n-octylthio)-1,3,5-triazine; di-(n-octylthio)ethyl 3,5-di-tert-butyl-4-hydroxybenzoate; and sorbitan hexa[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0054] These antioxidants are commercially available from Ciba Specialty Chemicals and include Irganox® 565, 1010, 1076, and 1726 (which are hindered phenols). These are primary antioxidants acting as free radical scavengers and can be used alone or in combination with other antioxidants, such as phosphite antioxidants like IRGAFOS® 168 available from Ciba Specialty Chemicals. Phosphite antioxidants are considered secondary antioxidants and are generally not used alone. They are primarily used as peroxide decomposers. Other available antioxidants are CYANOX® LTDP available from Cytec Industries and ETHANOX® 330 available from Albemarle Corp. Many of these antioxidants can be used alone or in combination with other such antioxidants. These compounds are added to the hot melt in small amounts (typically less than about 10% by weight) and have no effect on other physical properties.

[0055] Additional additives The adhesive compositions described herein may optionally include additional additives. Based on the total weight of the composition, the optional additional additives may be present in the composition at a weight percentage from greater than 0, about 0.1%, about 0.5%, or about 1% to about 5%, about 10%, about 20%, or about 30%, or between any pair of the foregoing values. The weight percentage of the optional additional additives may apply to the sum of all the additional additives present or to each additional additive individually.

[0056] Examples of additional additives include, but are not limited to, crosslinking agents, chain extenders, humectants, thixotropic agents, nucleating agents, surfactants, diluents, antisettling agents, flame retardant reinforcing agents, and any combination thereof. In some embodiments, optional additional additives include waxes, releasing agents, reinforcing fillers, pigments, heat stabilizers, UV stabilizers, plasticizers, rheology modifiers, processing aids, lubricants, release agents, biocides, or components or combinations thereof. Suitable reinforcing fillers include mineral fillers and glass fibers.

[0057] Table 1 below illustrates exemplary, non-limiting properties of some components of the hot melt adhesive described herein.

[0058] Table 1

[0059] Example System components TECHNOMELT® PS 9625 RE (“PS 9625”) is a pressure-sensitive hot melt adhesive available from Henkel Corp. (Bridgewater, NJ). AQUENCE® TACK 5157 (“TACK 5157”) is a water-based adhesive available from Henkel Corp. (Bridgewater, NJ). Sulfonated polyesters with a Tg of 35-38°C are available from Eastman. Sulfonated polyesters with a Tg of 51-55°C are available from Eastman. Rosin esters with a softening point of 85°C are available from Kraton. Rosin esters with a softening point of 100°C are available from Kraton. Maleic anhydride-modified rosin esters with a softening point of 105°C are available from Teckrez. Maleic anhydride-modified rosin esters with a softening point of 120°C are available from Teckrez. Terpene phenolic resins with a softening point of 96°C are available from Kraton. Polyethylene glycol with a molecular weight of 600 Daltons is available from Sigma Aldrich. Polyethylene glycol with a molecular weight of 1450 Daltons is available from Sigma Aldrich. Hindered phenolic and phosphite antioxidants are available from Everspring.

[0060] Test methods Initial viscosity method (Tack Method 1) Apply adhesive beads approximately 0.125 inches wide onto a 3-inch wide sheet of kraft paper at the specified application temperature. Leave the adhesive open for the specified time. Pre-cut a paper towel into 1-inch wide pieces. Place the paper towel substrate on top of the kraft paper and bond it by rolling it onto the adhesive layer using a 2.2 kg roller. Attach the paper towel to a force gauge and immediately measure the initial tack strength of the adhesive by manually pulling the paper towel through the force gauge. Repeat the initial tack test 5 times for each sample.

[0061] Initial tack method 2 Apply adhesive beads approximately 0.125 inches wide to a 2-inch wide strip of kraft paper at the specified application temperature. Leave the adhesive open for the specified time. Pre-cut the paper towel into 2-inch wide pieces. Place the kraft paper on top of the paper towel substrate and bond it by rolling it onto the adhesive layer with a 2.2 kg roller. Attach the kraft paper to a force gauge and immediately measure the initial tack strength of the adhesive by manually pulling the kraft paper with the force gauge. Repeat the initial tack test 5 times for each sample.

[0062] Ring-shaped initial tack test Pre-cut kraft paper into 1-inch x 5-inch strips. Apply adhesive beads approximately 0.125 inches wide to the kraft paper at the specified temperature. Keep the adhesive open for the specified time. Bend the specimen backwards with the adhesive facing outwards to form a teardrop shape. Secure the end of the specimen with 1-inch wide masking tape to form a 3-inch teardrop ring. Then, by holding the end of the masking tape and allowing the 3-inch ring to suspend freely in the fixture, insert the teardrop-shaped ring into the ring tack tester. Wrap the bottom panel with a paper towel substrate and insert the wrapped bottom panel into the panel guide. Perform the ring tack strength test according to ASTM D6195-03. Repeat the tack test 5 times for each specimen.

[0063] Water dispersibility test This water dispersibility test is adapted from the TAPPI modified version UM666 for hot melt adhesives. It is a hot melt adhesive re-slurryability test and is performed as follows: Weigh 0.5 grams of hot melt adhesive and allow it to cool. This is the “initial adhesive weight”. Place the pre-weighed adhesive in a Waring mixer with 350 ml of water at 160°F. Run the mixer at its maximum speed of 13900 RPM for 10 minutes. Pour the mixture through a 60-mesh sieve pre-weighed (“initial sieve weight”). Use additional water (room temperature) to rinse any residue from the mixer container through the sieve. Then rinse the sieve with clean room temperature water. Dry the sieve with any residual adhesive on it in an oven set to 110°F overnight. Then reweigh the sieve (“final sieve weight”). The % dispersibility can be calculated as follows: Viscosity measurement Viscosity was measured according to ASTM D3236 using a Brinell viscometer with rotor 27 at the applied temperature (350°F, 320°F, or 250°F).

[0064] Preparation method Prepare the adhesive formulation as follows: Weigh all ingredients and add them to a glass or metal container. Heat the contents to 350°F and mix until homogeneous.

[0065] Example 1 In this embodiment, the initial tack strength of the hot melt adhesive (formulation 1) described herein is compared with the initial tack strength of the pressure-sensitive adhesive (PS 9625) and the water-based adhesive (TACK 5157).

[0066] After one hour of open time, the initial tack strength of formulation 1 was 10 times that of TACK 5157.

[0067] Example 2 In this embodiment, the initial tack strength of the hot melt adhesive composition without tackifier (Formulation 2) and the hot melt adhesive compositions (Formulations 3-5) containing different amounts of rosin ester tackifier described herein are compared with the initial tack strength of the pressure-sensitive adhesive PS9625.

[0068] After a 1-hour open period, the initial tack strength of formulations 4 and 5 was higher than that of formulation 1. The initial tack strength of formulation 4 exceeded that of PS 9625.

[0069] Example 3 In this embodiment, the initial tack strength of the hot melt adhesive composition (formulation 6-11) containing different combinations of rosin esters and different amounts of sulfonated polyester described herein is compared with the initial tack strength of the pressure-sensitive adhesive PS 9625.

[0070] After one hour of open time, the initial tack strength of formulations 6, 7, 8, 9, 10, and 11 was higher than that of formulation 1. The initial tack strength of formulations 6, 7, 8, 9, 10, and 11 also exceeded that of PS 9625.

[0071] Example 4 In this embodiment, the initial tack strength of the hot melt adhesive composition (formulations 12-15) containing sulfonated polyester, polyethylene glycol and different amounts of modified rosin ester described herein is compared with the initial tack strength of pressure-sensitive adhesive PS 9625.

[0072] After a 1-hour open period, formulations 12 and 14 exhibited higher initial tack strengths than PS 9625. The initial tack values ​​of F12, F13, F14, and F15 were considered comparable to or higher than those of PS 9625.

[0073] Example 5 In this embodiment, the initial tack strength of the hot melt adhesive composition (formulation 16-19) containing polyethylene glycol with a molecular weight of 1450 described herein is compared with the initial tack strength of the pressure-sensitive adhesive PS 9625.

[0074] After a 1-hour open period, formulations 16, 17, 18, and 19 exhibited higher initial tack strength than PS 9625.

[0075] Example 6 The water dispersibility of the hot melt compositions (formulations 14 and 20) described herein was measured according to the methods described herein.

[0076] Both formulations 14 and 20 exhibited water dispersibility of 95% or greater.

[0077] Example 7 The initial tack strength of the hot melt adhesive composition (formulation 14) described herein was measured by an annular initial tack test with increasing open time.

[0078] During the 28-day open period, the initial tack strength of formulation 14 was higher than that of pressure-sensitive adhesive PS 9625.

[0079] Example 8 The thermal stability of the hot melt adhesive compositions (formulations 21 and 22) described herein was measured. Formulation 22 contains a maleic anhydride-modified resin tackifier.

[0080] Figure 1 The initial values ​​at 320°F were shown (respectively). Figure 1 A and Figure 1 B) and formulations 21 and 22 after standing at 320°F for 48 hours (Figures 2A and 2B, respectively). It can be seen that formulation 21 exhibits some phase separation after standing at 320°F for 48 hours, while formulation 22 remains homogeneous.

[0081] All patents and publications cited in this article are incorporated herein by reference in their entirety.

Claims

1. A water-dispersible hot melt adhesive, wherein the water-dispersible hot melt adhesive comprises: (a) Sulfonated polyester; (b) Rosin tackifier; (c) Plasticizers selected from polyethylene glycol, esters, and any combination thereof; and (d) Any available antioxidants, The hot melt adhesive mentioned above: (i) Has an opening period of at least approximately 4 weeks, during which, When measured according to ASTM D6195-03, the initial annular tack is approximately 3 to approximately 15 ounces of force per 0.125 square inches and remains within this range for approximately 4 weeks; and (ii) When measured according to TAPPI UM666, it has a water dispersibility of more than about 80%.

2. The water-dispersible hot melt adhesive according to claim 1, wherein the rosin tackifier comprises modified rosin ester, styrene-modified terpene resin, terpene phenolic resin, or any combination thereof.

3. The water-dispersible hot melt adhesive according to any one of claims 1-2, wherein the rosin tackifier comprises modified rosin ester.

4. The water-dispersible hot melt adhesive according to any one of claims 1-3, wherein the tackifier comprises rosin ester modified with maleic anhydride, glycidyl methacrylate, butyl acrylate, methyl methacrylate, acrylic acid, vinyltrimethoxysilane, or any combination thereof.

5. The water-dispersible hot melt adhesive according to any one of claims 1-4, wherein the tackifier comprises rosin ester modified with maleic anhydride.

6. The water-dispersible hot melt adhesive according to any one of claims 1-5, wherein the plasticizer comprises polyethylene glycol, sebacic acid ester, adipate ester, terephthalate, dibenzoic acid ester, glutaric acid ester, phthalate, azelaic acid ester, or any combination of any of the foregoing.

7. The water-dispersible hot melt adhesive according to any one of claims 1-6, wherein the plasticizer comprises polyethylene glycol.

8. The water-dispersible hot melt adhesive according to any one of claims 1-7, wherein the adhesive comprises: (i) Sulfonated polyester of about 5% w / w to about 90% w / w; (ii) polyethylene glycol of about 5% w / w to about 90% w / w; and (iii) Maleic anhydride-modified rosin esters, terpene phenolic resins, styrene-modified terpenes, or any combination thereof, of about 5% w / w to about 90% w / w.

9. The water-dispersible hot melt adhesive according to any one of claims 1-8, wherein the sulfonyl polyester comprises: (i) Glass transition temperature (T0) from about -20°C to about 65°C, for example from about 0°C to about 52°C g ); (ii) Melt viscosity of about 1,000 to about 150,000 cPs, for example about 5,000 to about 50,000 cPs (e.g., measured at 177°C); or (iii) Both (i) and (ii).

10. The water-dispersible hot melt adhesive according to any one of claims 1-9, wherein the tackifier comprises: (i) An acid value of approximately 5 to approximately 100; (ii) Softening point from about 0°C to about 150°C; or (iii) Both (i) and (ii).

11. The water-dispersible hot melt adhesive according to any one of claims 1-10, wherein, When measured according to TAPPIUM 666, the adhesive has a water dispersibility of more than about 95%.

12. The water-dispersible hot melt adhesive according to any one of claims 1-10, wherein, When measured at 250°F according to ASTM D3236, the adhesive has a viscosity of approximately 2000 cPs to approximately 15000 cPs.

13. An article comprising the water-dispersible hot melt adhesive according to any one of claims 1-12.

14. The article of claim 13, wherein the article is a bag, tissue paper, paper towel, kitchen paper towel, toilet paper, industrial paper towel, notebook, sticky note, or tape.

Images