Anti-rollback resealing adhesive

Abstract

Adhesive compositions are described that replace washers and liners in sealing applications for manually detachable packages. The adhesive composition is particularly useful for preventing leakage and spillage of its packaged contents during storage and transportation.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 202080006209.2, entitled "Back-off Resistant Re-sealable Adhesive", with a filing date of March 26, 2020 (the international application number of this application is PCT / US2020 / 024995), the entire content of which is incorporated herein by reference. Technical Field

[0002] The present invention relates to an adhesive composition that replaces gaskets and liners in manually detachable sealable container closures. The adhesive composition of the present invention is particularly useful for preventing back-off torque of container closures and thus preventing leakage and spillage of container contents during storage and transportation. Background Art

[0003] Threadlocking adhesives are commonly used to prevent back-off torque and to adhesively bond and interlock engageable structural fasteners to a final state. Such threadlocking adhesives have a strong adhesive force and cannot be separated by hand force. Low-force threadlocking adhesives can also be used, but once the bond is broken, the adhesive no longer has any cohesion and no longer interlocks.

[0004] With the rise of e-commerce, the shipping of liquid and gel products to consumers has also been increasing. Containers and packages that hold liquid and / or gel products must be leak-proof and provide safe shipping of the products.

[0005] Containers are sealed to prevent loss of their contents during storage and transportation. An application torque is applied to the closure of the container to seal the contents; however, over time and handling, some torque is lost, a phenomenon known as back-off. To compensate for this back-off torque, a higher initial application torque can be applied, which can cause container damage, equipment wear, or prevent the consumer from opening the container by hand force alone. Additional gaskets, induction seal liners, internal seals, valve seals, or liners are often applied to the container to prevent leakage; or auxiliary plastic liners or foam bag liners are added to the container, which increases the cost, complexity, and carbon footprint of the product. In addition, these additional seals add more steps to the packaging process, which requires several retoolings of the production line (and several round trips to the production line for shipping), further increasing the carbon footprint.

[0006] There is a continuing need for a more sustainable solution that minimizes the carbon footprint, cost, and complexity while maintaining the seal of the container and packaging during transportation and even after the container is opened. The present invention addresses this need in the art. Summary of the Invention

[0007] The present invention provides an alternative to, or in addition to, bands, gaskets, liners, or induction seals in containers and packaging.

[0008] One aspect of the present invention relates to an article including a first threaded member, the threaded portion of which is partially coated with a resealable adhesive. The resealable adhesive is a hot melt adhesive.

[0009] Another aspect of the present invention provides an article including the above-described first threaded member and a further second threaded member that engages with the first threaded member in a mating fashion, whereby the resealable adhesive is coated between the first threaded member and the second threaded member. The resealable adhesive is a hot melt adhesive and is characterized by having (1) a removal torque of about 4 to about 20 inch-pounds as measured according to ASTM D2063; and (2) a resealability torque of about 2 to about 15 inch-pounds as measured according to ASTM D2063.

[0010] In another aspect, the present invention provides an article including a non-threaded closure member having a circumference or perimeter dimension and a height dimension. The closure member is at least partially coated with a resealable adhesive including a hot melt adhesive.

[0011] In still another aspect, the present invention provides an article including the above-described non-threaded closure member and a second non-threaded member that engages with the first non-threaded member in a mating fashion, whereby the resealable adhesive is coated between the first non-threaded member and the second non-threaded member. The resealable adhesive is a hot melt adhesive and is characterized by having (1) a removal torque of about 4 to about 20 inch-pounds as measured according to ASTM D2063; and (2) a resealability torque of about 2 to about 15 inch-pounds as measured according to ASTM D2063.

[0012] Yet another aspect of the present invention provides a method of sealing a threaded member, the method comprising:

[0013] (a) providing a first threaded member;

[0014] (b) providing a second threaded member capable of cooperatively engaging with the first threaded member;

[0015] wherein at least one of the first threaded member and the second threaded member is at least partially coated with a resealable coating composition; and

[0016] (c) fittingly engaging the first threaded member and the second threaded member.

[0017] The resealable coating composition substantially fills the mating engagement space between the first threaded member and the second threaded member. The resealable coating composition is a hot melt adhesive characterized by having (1) a removal torque of about 4 to about 20 inch-pounds measured according to ASTM D2063; and (2) a resealable torque of about 2 to about 15 inch-pounds measured according to ASTM D2063.

[0018] Another aspect of the present invention provides a method for sealing a non-threaded component, the method comprising:

[0019] (a) providing a first non-threaded member having a circumference or perimeter dimension and a height dimension;

[0020] (b) providing a second non-threaded member capable of matingly engaging with the first non-threaded member;

[0021] wherein at least one of the first non-threaded member and the second non-threaded member is at least partially coated with a resealable coating composition; and

[0022] (c) matingly engaging the first non-threaded member and the second non-threaded member.

[0023] The resealable coating composition substantially fills the mating engagement space between the first non-threaded member and the second non-threaded member. The resealable coating composition is a hot melt adhesive characterized by having (1) a removal torque of about 4 to about 20 inch-pounds measured according to ASTM D2063; and (2) a resealable torque of about 2 to about 15 inch-pounds measured according to ASTM D2063. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a diagram of a threaded cap and a threaded neck lined with a resealable adhesive.

[0025] Figure 2 is a diagram of a non-threaded cap and a non-threaded neck lined with a resealable adhesive. DETAILED DESCRIPTION

[0026] The present invention provides a closure for a container lined with a resealable adhesive, which is not designed with additional means to seal off an opening and prevent loss of its contents. The closure lined with a resealable adhesive does not have gaskets, induction seal liners, inner seals, valve seals or liners typically made of metal, plastic, foam, paper and / or foil. The closure lined with a resealable adhesive is available for both threaded and non-threaded closures.

[0027] The term "application torque" is the torque force measured in inch-pounds required to screw the closure onto the container.

[0028] The term "back-off" refers to the relaxation of the forward thrust or loss of torque after the closure is applied. This can be affected by top load, compressibility and elasticity of the closure liner, consistency of the applied torque, and mechanical interaction between the closure and the bottle.

[0029] The term "removal torque" is the amount of force required to first loosen, open, unscrew or remove the closure from the container after it has been closed with a specific application torque.

[0030] The term "re-application torque" is the amount of torque re-applied to close the container.

[0031] The term "resealable torque" is the amount of force required to re-loosen, re-open, re-unscrew or remove the closure after the re-application torque has been applied to the closure, which measures the subsequent opening torque.

[0032] The terms "container" and "package" used interchangeably are the medium that holds the contents, including liquids, gels and solids.

[0033] The present invention relates to adhesively fixing a matingly engageable threaded member and its complementary threaded member such that the closure member adhesively binds and maintains a removal torque of about 4 to about 20 inch-pounds as measured by ASTM D2063. In addition, the resealable adhesive provides resealability and maintains a torque of about 2 to about 15 inch-pounds as measured by ASTM D2063 upon subsequent opening. Importantly, the resealable adhesive can retain about 40% to 100% of the re-application torque.

[0034] The present invention also relates to adhesively fixing a matingly engageable non-threaded member and its complementary non-threaded member with the same removal torque and resealability values as described above.

[0035] Once an application torque is applied to the component, the added resealable adhesive locks and seals the component. This resealable adhesive significantly increases the torque required to break or turn the joined threaded and non-threaded components of a container and provides leak and spill resistance for the container without the need for an additional gasket. A typical torque value of from about 4 to about 20 inch-pounds allows the connected components to be removed manually. Values greater than about 20 inch-pounds generally require additional tools to separate the components. Values less than about 2 inch-pounds may break the seal and cause the contents to leak.

[0036] The resealable adhesive of the present invention has a large gap-filling capacity, is non-messy, does not drip, can be applied to the container surface, and can be stored prior to use.

[0037] The resealable adhesive is a hot melt adhesive. Typically, the hot melt adhesive comprises: a polymer, a tackifier, optionally a wax, a diluent / plasticizer, an antioxidant, and other additives. The polymers include: (1) olefin copolymer block copolymers and random copolymers produced by metallocene catalyzed polymerization; (2) hydrogenated styrene block copolymers which are substantially saturated materials having styrene end blocks and ethylene-butene, ethylene-propylene, butene-butene, or isobutene middle blocks and having a diblock content of less than about 70%, preferably less than about 50% and more preferably less than about 30%; (3) amorphous polyalphaolefin polymers which include random copolymers or terpolymers of ethylene, propylene, and butene, and other substantially amorphous or semi-crystalline propylene-ethylene polymers; (4) polyester copolymers, and (5) ethylene vinyl acetate which contains from about 15 to about 50 weight % vinyl acetate and ethylene-n-butyl acrylate content.

[0038] In one embodiment, the polymer or polymer-containing mixture is present in an amount of from about 10 to about 70 weight %, preferably from about 15 to about 45 weight %, based on the total weight of the hot melt adhesive.

[0039] The desirability and selection of a particular tackifier or tackifying agent can depend on the specific type of polymer used. Suitable tackifiers include any compatible resin or mixtures thereof, such as: (1) natural or modified rosins, such as gum rosin, wood rosin, tall oil rosin, distilled rosin, hydrogenated rosin, dimerized rosin, and polymerized rosin; (2) glycerol and pentaerythritol esters of natural or modified rosins, such as glycerol esters of light wood rosin, glycerol esters of hydrogenated rosin, glycerol esters of polymerized rosin, pentaerythritol esters of hydrogenated rosin, and phenolic modified pentaerythritol esters of rosin; (3) copolymers and terpolymers of natural terpenes, such as styrene / terpene and α-methylstyrene / terpene; (4) polyterpene resins having a softening point of about 80 - 150 °C as determined by ASTM method E28-18; the latter polyterpene resins are typically produced by the polymerization of terpene olefins (such as the bicyclic monoterpene known as pinene) at moderate to low temperatures in the presence of a Friedel-Crafts catalyst; also included are hydrogenated polyterpene resins; (5) phenolic modified terpene resins and their hydrogenated derivatives, such as resin products obtained by the condensation of bicyclic terpenes and phenol in an acidic medium; (6) aliphatic petroleum hydrocarbon resins having a ring-and-ball softening point of about 70 °C to 135 °C; the latter resins are obtained by the polymerization of monomers consisting mainly of olefins and diolefins; also included are hydrogenated aliphatic petroleum hydrocarbon resins; (7) alicyclic petroleum hydrocarbon resins and their hydrogenated derivatives; and (8) aliphatic / aromatic or alicyclic / aromatic copolymers and their hydrogenated derivatives.

[0040] In one embodiment, the tackifier or mixture containing the tackifier is present in an amount of about 5 to about 60 weight percent, based on the total weight of the hot melt adhesive.

[0041] Waxes include petroleum-based conventional waxes, natural-based waxes, functionalized waxes, and low molecular weight polyolefin copolymers can be used in the practice of the present invention.

[0042] In one embodiment, the wax or mixture containing the wax is present in an amount of about 10 to about 60 weight percent, based on the total weight of the hot melt adhesive.

[0043] Diluents are defined herein as oils, plasticizers, liquid tackifiers (having a ring-and-ball softening point below about 25 °C), synthetic liquid oligomers, and mixtures thereof.

[0044] Based on the total weight of the hot melt adhesive, the diluent or mixture containing the diluent is optionally present in an amount not exceeding about 10 weight percent.

[0045] Antioxidants or stabilizers can also be included in the hot melt adhesive in an amount not exceeding about 3 weight percent, more typically in an amount not exceeding about 1 percent.

[0046] Other additives that are conventionally used in hot melt adhesives to meet different properties and specific application requirements can also be added to the adhesive compositions of the present invention. Such additives include, for example, fillers, microsphere pigments, flow modifiers, dyes, corrosion inhibitors, lubricants (such as greases, oils, and waxes), and / or coupling agents, and these substances can be incorporated into the adhesive in smaller or larger amounts depending on the purpose.

[0047] Depending on the purpose of the application requirements, based on the total weight of the hot melt adhesive, other additives can be present in an amount not higher than 30% by weight.

[0048] Exemplary hot melt adhesives include rubber-based adhesives, ethylene vinyl acetate-based adhesives, metallocene-catalyzed olefin-based adhesives, and Ziegler-Natta-catalyzed olefin-based adhesives.

[0049] Regardless of the specific formulation, the hot melt adhesive formulation has sufficient viscosity and sag resistance so that the adhesive can be easily applied in its molten state to the threads and non-threads of mating components without subsequent dripping, sagging, or displacement of the adhesive before mating and locking its complementary component. In one embodiment, the hot melt adhesive is a low application temperature adhesive to reduce carbonization of the substrate component. In another embodiment, the hot melt adhesive has pressure-sensitive properties. The resealable adhesive is pre-applied to the surface area of the component to be joined with the complementary mating component; then this pre-applied medium can be cooled and / or solidified in any suitable manner, for example, by ambient (room temperature) or lower temperatures to accelerate the hardening of the molten hot melt adhesive. In another embodiment, the hot melt adhesive is applied to the component in powder or non-molten state, and the component with the applied adhesive is heated.

[0050] The contents of the hot melt adhesive are combined as known in the art, applied to at least a portion of the threaded or non-threaded component and dried. A sufficient amount of the hot melt adhesive is applied to the threaded or non-threaded component, and when the component is matingly engaged with its complementary component, the hot melt adhesive is coated between the two components, fills the gap between the two components, and provides a removal torque.

[0051] As Figure 1 shown, the hot melt adhesive (4) is applied to the region (3) of the threaded neck. The neck component is matingly engaged to the thread (2) of the cap (1).

[0052] Moreover, as Figure 2 shown, the hot melt adhesive (30) is applied to the neck (20). The neck is matingly fitted on the cap (10).

[0053] Once applied to one of the components, the resealable adhesive remains on the surface of the threaded or non-threaded component until it mates with its complementary component. In use, the component having the pre-applied resealable adhesive thereon is brought into contact with the mating surface of the complementary component, wherein the complementary component preferably may have a resealable adhesive previously applied to its surface to facilitate the securing of the joined components. In this manner, a differential pressure is applied to the components that are cooperatively joined.

[0054] In one embodiment, the resealable adhesive may be applied at a coating level of from about 0.001 to about 1 g / in 2 , preferably from about 0.01 to about 0.7 g / in 2 , more preferably from about 0.02 to about 0.5 g / in 2 to the surface of one of the closure components.

[0055] The resealable adhesive may be applied in any suitable manner, such as by extrusion, spraying, dipping, roll coating, contact application or in any other suitable manner, depending on the thickness, flow characteristics and viscosity characteristics required or present in the particular end-use application of the composition. A uniform thickness of the resealable adhesive at the closure component is desirable; however, an uneven thickness will become more uniform under an applied force, in which case mating the two components will squeeze the resealable adhesive together to form the desired seal.

[0056] In some embodiments, the resealable adhesive is transparent or water-white. In other embodiments, pigments are added to color or stain the resealable adhesive to match the container color.

[0057] In another embodiment, the present invention is a method of adhesively joining a threaded or non-threaded component by the steps of:

[0058] (a) providing a first threaded or non-threaded component;

[0059] (b) providing a second threaded or non-threaded component capable of matingly engaging with the first component;

[0060] wherein at least one of the first and second components is at least partially coated with a resealable coating composition; and

[0061] (c) matingly engaging the first threaded component and the second threaded component.

[0062] The resealable coating composition substantially fills the mating engagement space between the first and second members. The resealable coating composition is a hot melt adhesive characterized by having (1) a removal torque of about 4 to about 20 inch-pounds as measured according to ASTM D2063; and (2) a resealable torque of about 2 to about 15 inch-pounds as measured according to ASTM D2063.

[0063] The present invention can be used in place of bags, tapes, films, strips, gaskets, liners, cords and various other shaped sheets that can be applied to container closure members, or in addition to bags, tapes, films, strips, gaskets, liners, cords and various other shaped sheets that can be applied to container closure members, the present invention can also be used.

[0064] Container closure members in which the present invention can be implemented include any structural elements such as caps and closures, screw tops, snap fastener elements, tongue and groove fastener elements, hook and loop fastener elements, press fit elements, pump dispensers, etc., which can be adhesively joined in mating engagement with complementary mating structures. The closure member and the complementary member can thus include a cap and closure assembly that engages in a threaded or non-threaded manner and has a resealable adhesive that fills the gap between the mating members.

[0065] The present invention can be used as caps, lids and closures and can be formed into container (bottle) necks, screw caps, roll on Pilfer proof closures, safety closures, dispensing and metering closures, trigger spray closures, safety closures, valve closures, tube caps, tamper-evident closures, sports caps, snap hinge caps, screw caps, push-pull closures, pours and dropper closures, child resistant closures, etc.

[0066] The above caps and closures are typically made of polypropylene, polyethylene, high density polyethylene, low density polyethylene, polyvinyl chloride and / or polyethylene terephthalate.

[0067] Examples

[0068] All torque values were measured according to ASTM D2063 using a Mark 10 model MTT 01-50.

[0069] A test sample hot melt adhesive was formulated with ethylene vinyl acetate polymer (30 wt%), tackifier (60%), wax (8%) and additive (2%).

[0070] Samples of the molten sample adhesive at various coating weights (in grams per square inch) were applied to the first threaded member.

[0071] At least three threaded members were conditioned at room temperature (21 - 25 °C) for 24 hours and each member was threaded by hand (applying force) onto its mating second threaded member. The removal torque of the mated members was then tested and recorded in Table 1.

[0072] Once removed, each member was re - closed at the specified re - application torque and the reseal torque was tested with the same tester. The reseal torque values and the percentage of retained torque are also listed in Table 1.

[0073] Table 1

[0074]

[0075] The coating weights of the first three samples were such that removal torque and reseal torque in the hand - openable range could be obtained. Moreover, the reseal adhesive retained greater than about 47% of the torque.

[0076] It will be apparent to those skilled in the art that many modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. The specific embodiments described herein are provided by way of example only and the invention is limited only by the terms of the appended claims and the full scope of equivalents to those claims.

Claims

1. An article, comprising A first threaded member, wherein the threads of the first threaded member are at least partially coated with a resealable adhesive comprising a hot melt adhesive, wherein the coating weight of the resealable adhesive is from 0.02 g / in 2 to 0.07 g / in 2 , wherein the hot melt adhesive comprises an adhesive based on: (1) an olefin copolymer block copolymer and random copolymer produced by metallocene catalyzed polymerization; (2) an amorphous polyalphaolefin polymer comprising a random copolymer or terpolymer of ethylene, propylene and butene, and other substantially amorphous or semi-crystalline propylene-ethylene polymers; or (3) a polyester copolymer, a second threaded member matingly engaged with the first threaded member, whereby the resealable adhesive is applied between the first threaded member and the second threaded member; wherein the resealable adhesive is characterized by having a removal torque of about 4 to about 20 inch-pounds as measured according to ASTM D2063; wherein the threaded member has a resealable torque of about 2 to about 15 inch-pounds as measured according to ASTM D2063, wherein the resealable adhesive can retain 40% to 100% of the reapplication torque, and a polymer or a polymer-containing mixture is present in an amount of 15 to 45% by weight based on the total weight of the hot melt adhesive.

2. The article according to claim 1, wherein the first threaded member or the second threaded member is independently made of polypropylene, polyethylene, high density polyethylene, low density polyethylene, polyvinyl chloride or polyethylene terephthalate.

3. The article according to claim 1, wherein the first threaded member is a cap, lid or closure.

4. The article according to claim 1, wherein the first threaded member is a container neck or bottleneck.

5. An article, comprising A non-threaded closure member for an area having a circumferential or perimeter dimension and a height dimension, wherein the area of the closure member is at least partially coated with a resealable adhesive comprising a hot melt adhesive, wherein the coated weight of the resealable adhesive is 0.02 g / in 2 to 0.07 g / in 2 , wherein the hot melt adhesive comprises an adhesive based on: (1) olefin copolymer block copolymers and random copolymers produced by metallocene-catalyzed polymerization; (2) amorphous polyalpha-olefin polymers, which include random copolymers or terpolymers of ethylene, propylene, and butene, and other substantially amorphous or semi-crystalline propylene-ethylene polymers; or (3) polyester copolymers, a second non-threaded member matingly engaged with the area of the first non-threaded member, whereby the resealable adhesive is applied between the first non-threaded member and the second non-threaded member; wherein the resealable adhesive is characterized by having a removal torque of about 4 to about 20 inch-pounds as measured according to ASTM D2063; wherein the threaded member has a resealable torque of about 2 to about 15 inch-pounds as measured according to ASTM D2063, wherein the resealable adhesive can retain 40% to 100% of the reapplication torque, and a polymer or a polymer-containing mixture is present in an amount of 15 to 45% by weight based on the total weight of the hot melt adhesive.

6. The article according to claim 5, wherein the first non-threaded member or the second non-threaded member is independently made of polypropylene, polyethylene, high density polyethylene, low density polyethylene, polyvinyl chloride or polyethylene terephthalate.

7. The article according to claim 5, wherein the first non-threaded member is a cap, lid or closure.

8. The article according to claim 5, wherein the first non-threaded member is a container neck or bottleneck.

9. A method of sealing a member, comprising: (a) providing a first member; (b) providing a second member capable of matingly engaging with the first member; wherein at least one of the first member and the second member is at least partially coated with a resealable coating composition, wherein the coating weight of the resealable adhesive is 0.02 g / in 2 to 0.07 g / in 2 ; (c) matingly engaging the first member and the second member, whereby the resealable coating composition substantially fills the mating engagement space between the first member and the second member; The resealable adhesive is a hot melt adhesive, characterized by having a removal torque of about 4 to about 20 inch-pounds as measured by ASTM D2063, wherein the hot melt adhesive comprises an adhesive based on: (1) olefin copolymer block copolymers and random copolymers produced by metallocene catalyzed polymerization; (2) amorphous polyalphaolefin polymers, which include random copolymers or terpolymers of ethylene, propylene, and butene, and other substantially amorphous or semicrystalline propylene-ethylene polymers; or (3) polyester copolymers; wherein the resealable adhesive has a resealable torque of about 2 to about 15 inch-pounds as measured by ASTM D2063, wherein the first member or the second member is independently made of polypropylene, polyethylene, high density polyethylene, low density polyethylene, polyvinyl chloride, or polyethylene terephthalate, wherein the resealable adhesive can retain 40% to 100% of the reapplication torque, and the polymer or polymer-containing mixture is present in an amount of 15 to 45 weight percent based on the total weight of the hot melt adhesive.

10. The method of sealing a member according to claim 9, wherein at least one of the first member and the second member is a cap, lid, or closure.

11. The method of sealing a member according to claim 9, wherein the first member and the second member are threaded members.

12. The method of sealing a member according to claim 9, wherein the first member and the second member are non-threaded members.

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