Adhesive delivery hose with barrier layer and method of use

Abstract

The invention relates to an adhesive delivery hose with a barrier layer and a method of use. The adhesive transfer hose is a multi-layer hot melt adhesive transfer hose. The delivery hose has a barrier layer that prevents or minimizes the ingress of oxygen and other gases into the conduit of the hose. The transfer hose has at least one structural layer covering an outer surface of the barrier layer to help the hose withstand high fluid pressure. The barrier layer prevents the adhesive from discoloring and coking when the hot melt adhesive transported within the hose is heated to from about 250 DEG F up to and including 450 DEG F for an extended period of time.

Description

[0001] Divisional Application Instructions

[0002] This application is a divisional application of the Chinese invention patent application with the application date of July 14, 2017, the application number of 201710574504.8, and the invention name of "Adhesive transfer hose with barrier layer and method of use".

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 363,138, filed on July 15, 2016, the disclosure of which is hereby incorporated by reference herein. Technical Field

[0005] The present disclosure relates generally to adhesive delivery hoses, and more particularly to adhesive delivery hoses having a barrier layer that prevents or minimizes the ingress of air into a conduit of the hose. Background Art

[0006] Hot melt adhesives, including conventional hot melt adhesives and reactive moisture-curing hot melt polyurethane adhesives ("hot melt PURs"), are commonly used in a variety of applications where a stable surface-to-surface bond must be formed. In addition, hot melt adhesives are used to secure a variety of similar and dissimilar materials together in a mating relationship, such as wood, plastics, corrugated films, paper, paperboard materials, metals, rigid polyvinyl chlorides (PVCs), fabrics, leather, and the like. These adhesives are particularly useful in applications where it is desirable for the adhesive to cure rapidly after being melted and dispensed.

[0007] In conventional hot melt adhesives, typically a polymer, a tackifier, and some other additives such as antioxidants are mixed together to produce an adhesive. These materials tend to form a bond by rapidly solidifying as they cool from a molten state, and have the advantage of being relatively easy to apply. In hot melt PURs, isocyanate-terminated polyurethane polymers are produced by polymerization of polyols with excess polyisocyanate compounds. Hot melt PURs solidify (e.g., crosslink) in the presence of extraneous moisture.

[0008] Typically, the hot melt adhesive in solid form occurs with a variety of shapes and sizes, and is supplied to a melter, which comprises a heated box and / or a heated grid to produce the hot melt adhesive of melting. Solid hot melt adhesive can also be supplied to a barrel or a bucket, in which the adhesive is melted by using a pressure plate. After heating, the molten adhesive is pumped to an applicator or a distributor by a heated hose, and the hose maintains the molten material at the application temperature required, and the applicator or a distributor are sometimes referred to as dispensing "guns" or gun modules, which comprise valves and nozzles. Exemplary heated hoses are described in co-owned U.S. Patent No. 6,738,566, which is incorporated herein by reference in its entirety.

[0009] However, a common problem of heated hoses is the discoloration of the molten hot melt adhesive caused. This discoloration may adversely affect the "pot life" of the hot melt adhesive, because the discoloration can indicate that the hot melt adhesive has been degraded. As used herein, "pot life" is the maximum time at system temperature before the adhesive begins to degrade and thus causes increased viscosity, coking and / or gelling. This can be particularly problematic in systems requiring relatively low flow rates. In some applications, if the molten adhesive is retained for too long in the heated hose, its "pot life" can be shortened. The shortening of the "pot life" of thermoplastic adhesives may cause operational problems, such as filter clogging, and may further require cleaning the hose after coking has occurred.

[0010] Coking is the adhesive that has turned black or burned, and can be caused by a variety of reasons, such as heating the hot melt adhesive for too long and / or heating it at too high a temperature. In addition, it has been observed that the introduction of oxygen into the hose is the main cause of hot melt adhesive coking. Although hot melt adhesive can be protected by specific additives such as antioxidants, the molten adhesive should not be kept in the extended period of time under the molten state, because the molten adhesive can decompose. Therefore, the effect of heating, time and oxidation begins to decompose the adhesive. For example, the polymer chain of the adhesive forms an active site, and the active site can be combined to form a gel that adheres to the cracks in the hose wall and the melt tank, thereby forming an anchor point, which inhibits the molten adhesive from flowing through the system effectively. In addition, coking can harden and break into pieces, and the piece blocks the filter and the nozzle.

[0011] A major problem associated with coking is that once coking enters the hot melt system, it is very difficult and sometimes impossible to flush it out. Once coking is formed, it may cause product quality problems, expensive maintenance problems and work stoppages. In some cases, the entire hot melt system may need to be disassembled and the compounds must be burned off in a burn-off furnace to completely remove the coking. This process is very time-consuming and expensive. Therefore, it is desirable to prevent or reduce the formation of coking before it becomes a problem in the system.

[0012] The inventors of the present disclosure have discovered that one way to prevent adhesive charring is to eliminate or minimize the ingress of oxygen into the hose. However, preventing or minimizing the introduction of oxygen into a conventional adhesive delivery hose can cause significant problems because a typical hose that is long and has a small diameter provides a large delivery area for a small amount of adhesive. Therefore, oxygen ingress into the delivery hose is more likely to occur than oxygen ingress into the adhesive melting tank. For example, as long as oxygen is prevented from entering the hose during adhesive delivery, the adhesive can be in the heated hose for a long period of time and experience minimal discoloration.

[0013] Furthermore, conventional hot melt hoses do not take into account the effect of the partial pressure of oxygen on the flow through a typical hose core. Antioxidants and degradation processes consume oxygen within the hose, creating a driving force for diffusion from the atmosphere despite the fact that the hose can be hydraulically pressurized to hundreds of psi. Furthermore, hoses used in high temperature applications of 500°F and higher, such as for polymer processing, far exceed the requirements of hoses that fully melt the adhesive in solid form into a molten, flowable state.

[0014] Therefore, discoloration and related degradation of hot melt adhesives are caused by extraneous oxygen penetrating into the hot melt adhesive delivery hose and / or passing through the layers of the hot melt adhesive delivery hose and reacting with the hot melt adhesive at the melting temperature. Therefore, there is a need for a hot melt adhesive delivery hose having an impermeable barrier layer for preventing or minimizing the ingress of oxygen into the hose delivering the molten hot melt adhesive, thereby eliminating or at least greatly reducing discoloration and corresponding charring of the molten hot melt adhesive during its residence time in the heated hose. Summary of the invention

[0015] A multilayer hot melt adhesive delivery hose is provided. The delivery hose includes: a conduit for transporting heated liquid hot melt adhesive; an impermeable barrier layer, the barrier layer being configured to prevent oxygen from entering the conduit of the hose transporting molten hot melt adhesive; and at least one structural layer, the structural layer covering the outer surface of the barrier layer and being configured to withstand high fluid pressure. More particularly, the barrier layer is configured to prevent oxygen from entering through the conduit and entering the hot melt adhesive. A heater may also be provided for maintaining the hot melt adhesive at a set point temperature, wherein the heater is adapted to be electrically connected to a power source that is controlled to maintain the set point to approximately 450°F or below for an extended period of time.

[0016] The barrier layer and the structural layer each include a thermally stable material. In addition, the barrier layer prevents the hot melt adhesive from charring when heated to 450°F or less for an extended period of time. The barrier layer is a flexible metal tube that may include a plurality of seamless corrugations. Alternatively, the barrier layer may be a metal strip, such as an aluminum strip.

[0017] The at least one structural layer may include a braided sleeve, which may be made of stainless steel. The flexible metal tube may also be a stainless steel metal tube. In addition, the at least one structural layer may include two overlapping braided sleeves, and the outer cover layer has a special multi-layer structure, which covers the outer surface of the at least one structural layer.

[0018] The outer cover layer can include a heating wire sublayer, an insulating sublayer covering the heating wire sublayer, and a protective sublayer covering the insulating sublayer. It should be appreciated that the outer cover layer can alternatively include a heating tape sublayer.

[0019] In addition, the barrier layer can be a metal coating applied to the inner tube. It should be appreciated that the flexible metal tube may include a liner disposed therein. The liner includes a thermally stable polymer material and is configured to improve the flow of molten hot melt adhesive through the flexible metal tube. In addition, the liner includes a smooth inner surface that promotes fluid flow and prevents material incompatibility issues between the molten hot melt adhesive and the flexible metal tube.

[0020] The barrier layer unexpectedly prevents the hot melt adhesive from discoloring and scorching when heated to temperatures of about 250°F or higher, up to and including about 450°F, for extended periods of time.

[0021] In addition, a method of transporting a hot melt adhesive is disclosed, the method comprising the steps of transporting the hot melt adhesive at a temperature at or below about 450°F through a multi-layer transport hose, the multi-layer transport hose comprising a flexible metal tube, the flexible metal tube forming an impermeable barrier layer, the barrier layer being configured to prevent oxygen from entering the conduit of the hose. It should be appreciated that the flexible metal tube is heated to a temperature at or below about 450°F. Alternatively, the flexible metal tube is capable of transporting the hot melt adhesive at a temperature at or below about 400°F. In addition, the flexible metal tube is capable of transporting the hot melt adhesive at a temperature at or below about 350°F.

[0022] An unexpected effect of the barrier layer is that no significant discoloration or scorching of the hot melt adhesive occurs when the hot melt adhesive is maintained inside the hose for at least twenty-four hours, at least forty-eight hours, seventy-two hours, or ninety-six hours.

[0023] According to another aspect of the present disclosure, a multi-layer hot melt adhesive delivery hose is provided, wherein at least one of the layers is an oxygen barrier layer that prevents or minimizes the ingress of oxygen into a conduit of the hose transporting molten hot melt adhesive.

[0024] According to another aspect of the present disclosure, there is provided an apparatus for melting and dispensing hot melt adhesive. The apparatus comprises: a chamber for receiving the hot melt adhesive in solid form; a heating device coupled to the chamber and configured to receive the hot melt adhesive for liquefying the hot melt adhesive in solid form; and a multi-layer hot melt adhesive delivery hose, the multi-layer hot melt adhesive delivery hose being fluidly coupled to the heating device.

[0025] In addition, a method for dispensing a hot melt adhesive, such as a packaging grade hot melt adhesive, is provided. The method includes the steps of melting the hot melt adhesive; transporting the molten hot melt adhesive to a dispenser through a hose; heating the molten hot melt adhesive in the hose at a set point temperature of about 450°F or less; preventing oxygen transmission into the adhesive in the hose using a barrier layer; and dispensing the hot melt adhesive onto a substrate.

[0026] The method for dispensing hot melt adhesive does not produce significant discoloration and scorching of adhesive when adhesive remains on the inside of the hose for at least 24 hours. In addition, significant discoloration and scorching of adhesive do not occur when adhesive remains on the inside of the hose for at least 48 hours to 96 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1A is a perspective schematic diagram of a conventional hot melt adhesive delivery hose.

[0028] Figure 1B yes Figure 1A An end view of a hot melt adhesive delivery hose is shown in FIG.

[0029] Figure 2A is a perspective schematic diagram of a hot melt adhesive delivery hose according to an embodiment of the present invention.

[0030] Figure 2B yes Figure 2A An end view of a hot melt adhesive delivery hose is shown in FIG.

[0031] Figure 3A FIG. 4 is a perspective schematic diagram of a hot melt adhesive delivery hose according to another embodiment of the present invention.

[0032] Figure 3B yes Figure 3A An end view of a hot melt adhesive delivery hose is shown in FIG.

[0033] Figure 4A FIG. 4 is a perspective schematic diagram of a hot melt adhesive delivery hose according to another embodiment of the present invention.

[0034] Figure 4B yes Figure 4A An end view of a hot melt adhesive delivery hose is shown in FIG.

[0035] Figure 5A FIG. 4 is a perspective schematic diagram of a hot melt adhesive delivery hose according to another embodiment of the present invention.

[0036] Figure 5B yes Figure 5A An end view of a hot melt adhesive delivery hose is shown in FIG.

[0037] Fig. 6A is a perspective schematic diagram of a hot melt adhesive delivery hose according to an embodiment of the present invention.

[0038] Figure 6B yes Fig. 6A An end view of a hot melt adhesive delivery hose is shown in FIG.

[0039] Figure 7 Disc samples of Henkel 314C hot melt adhesive that have been heated in a laboratory oven at 350°F for 0 to 95 hours are illustrated, showing various states of color change.

[0040] Figure 8 Shown based on Figure 7 Schematic qualitative color change grading scale from 1 to 10 of the samples shown in .

[0041] Fig. 9 Various exemplary test hoses are illustrated.

[0042] Fig.10 Indicated Fig. 9 An end cap for an exemplary test hose is shown in FIG.

[0043] Fig.11 The placement of the test samples reported in Table 1 below prior to the start of the experiments described herein is illustrated.

[0044] Fig.12 Illustrated are samples 1b, 1a, and 1c (from left to right) after completion of the experiments described herein.

[0045] Fig.13A is a perspective schematic diagram of a hot melt adhesive delivery hose according to the present disclosure.

[0046] Fig. 13B yes Fig.13A An end view of a hot melt adhesive delivery hose is shown in FIG.

[0047] Fig.14A is a perspective schematic diagram of a hot melt adhesive delivery hose according to another aspect of the present disclosure.

[0048] Fig. 14B yes Fig.14A An end view of a hot melt adhesive delivery hose is shown in FIG.

[0049] Fig.15A is a perspective schematic diagram of a hot melt adhesive delivery hose according to another aspect of the present disclosure.

[0050] Fig. 15B yes Fig.15A An end view of a hot melt adhesive delivery hose is shown in FIG.

[0051] Fig.16 is a graphical representation comparing the amount of char formed in a hot melt adhesive over time using a competitor's transfer hose as compared to the transfer hose of the present disclosure.

[0052] It should be noted that the drawings are not necessarily drawn to scale, but are drawn to provide a better understanding of the contents of the drawings and are not intended to limit the scope, but rather to provide exemplary illustrations. In addition, implementations of the present disclosure are described with reference to the accompanying drawings, wherein like reference numerals indicate like parts throughout the drawings. DETAILED DESCRIPTION

[0053] As described above, discoloration of the hot melt adhesive that occurs in conventional hot melt adhesive delivery hoses can adversely affect the "pot life" of the hot melt adhesive by subsequently causing increased viscosity, charring, or coagulation. It is observed that such discoloration can be caused by adventitious oxygen that has penetrated into the layers of the hot melt adhesive delivery hose and / or passed through the layers and reacted with the hot melt adhesive at melting temperature conditions.

[0054] Therefore, a multi-layer hot melt adhesive delivery hose including a barrier layer is disclosed. The barrier layer is used to prevent or minimize oxygen ingress into the conduit of the hose that delivers the molten hot melt adhesive, thereby reducing discoloration of the molten hot melt adhesive. In addition, inhibiting or reducing oxygen ingress can also maintain the desired "pot life" of the hot melt adhesive.

[0055] The oxygen barrier layer can be a special layer of the hose, or a composite or mixture of a thermally stable polymer and an inorganic additive that functions as an inner tube, as will be explained in more detail below. Also described are hot melt adhesive apparatus incorporating one or more multi-layer hot melt adhesive hoses and methods for delivering hot melt adhesive and making hot melt adhesive delivery hoses.

[0056] In one aspect of the disclosure, the barrier layer is impermeable and thus prevents oxygen from diffusing into the conduit of the hose. In another aspect of the disclosure, the oxygen barrier layer provides a degree of oxygen permeability to the hot melt adhesive delivery hose that is sufficiently low to reduce discoloration compared to a hot melt adhesive delivery hose without an oxygen barrier layer. For example, the oxygen permeability of the hose with the oxygen barrier layer can be reduced by about 10 times, about 100 times, or about 1000 times or more.

[0057] refer to Figure 1A and Figure 1B , a simplified prior art multi-layer hot melt adhesive delivery hose 100 is shown having an inner tube 102 for delivering the hot melt adhesive, a structural layer 104 for strength and protection, and an outer cover 106. The inner tube 102 forms the running core of the hose 100 through which the molten hot melt adhesive actually flows.

[0058] The inner tube 102 is made of a polymer material that can withstand relatively high temperatures, such as polytetrafluoroethylene (PTFE). Because PTFE or other similar high melting temperature polymers are generally unable to withstand the high fluid pressures used to transfer molten hot melt adhesives, the inner tube 102 needs to be reinforced by a reinforcement layer or structural layer 104.

[0059] The structural layer 104 disposed around the exterior of the inner tube 102 and used to provide strength and protection to the inner tube 102 may include a braided sleeve made of a thermally stable material. As described above, the hot melt adhesive is heated to a set point temperature sufficient to melt the solid form into a molten flowable state, and the set point temperature is generally in the range of from about 100°C (about 212°F) to about 430°C (about 450°F). In addition, to promote the flow of the molten hot melt adhesive, the hot melt adhesive delivery hose may experience a pressure of up to about 1500 psi (about 10.3 MPa) of operating pressure. Therefore, the structural layer 104 is used to provide the hot melt adhesive delivery hose with the desired physical integrity.

[0060] Polymer barrier layer

[0061] Thus, the present disclosure provides a multi-layer hot melt adhesive delivery hose 200 that is configured to prevent and / or reduce the amount of gas, such as oxygen, from penetrating the hose and contacting the hot melt adhesive therein. Figure 2A and Figure 2B As shown in , the oxygen barrier layer 203 of the hot melt adhesive delivery hose 200 can be a special layer in contact with the inner surface of the inner tube 102, and the inner tube 102 is covered by the structural layer 104 and the outer cover 106. Alternatively, as shown in Figure 3A and Figure 3BAs shown in , the oxygen barrier layer 203 can be a special layer in contact with the outer surface of the inner tube 102 or the inner surface of the structural layer 104, and the structural layer 104 is covered by the outer cover 106. Figure 4A and Figure 4B As shown in , the oxygen barrier layer 203 may be a special layer outside the circumference of the inner tube 102 and in contact with the outer surface of the structural layer 104 or the inner surface of the outer cover 106. Figure 5A and Figure 5B As shown in , the oxygen barrier layer 203 may surround the inner tube 102 , the structural layer 104 , and the outer cover 106 , and be formed as a special layer in contact with the outer surface of the outer cover 106 .

[0062] With reference to Fig. 2 to Fig. 5, inner tube 102 forms the running core of hose 200, and molten hot melt adhesive actually flows through this running core.Oxygen barrier layer 203 may include polymer material, metal material or its combination.The selection of material may depend on the position of oxygen barrier layer in hot melt adhesive transmission hose.For example, inner tube 102, structural layer 104 and / or heating tape sublayer are located at the position called "hot zone", and the hot zone is close to or higher than the temperature of molten hot melt adhesive.Alternatively, the outer surface of the isolation or protection sublayer of outer layer 106 is arranged radially from the hot zone and is arranged outside the hot zone, and is therefore at a lower temperature.Therefore, the material whose melting temperature is higher than the desired operating temperature of the molten hot melt adhesive can be used to construct the oxygen barrier layer in or outside the hot zone.

[0063] When the oxygen barrier layer 203 is in the hot zone, the material of the oxygen barrier layer 203 should have a melting point that is sufficiently higher than the desired operating temperature of the molten hot melt adhesive. For example, the melting point of the material of the oxygen barrier layer 203 constructed in the hot zone is preferably at least about 50°F or higher, or about 100°F or higher, or about 200°F or higher than the desired operating temperature of the molten hot melt adhesive. Examples of such materials with sufficiently high melting points include, but are not limited to, metallic materials, such as metal foil films or metallic coatings. Non-limiting examples of metallic materials include aluminum foil backed tapes, or metals or metallic coatings applied by sputtering, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), or atomic layer deposition (ALD). The surface of the layer to which the metal or metallic coating is applied can be modified to improve metal adhesion, such as described in U.S. Patent No. 6,420,041, which is incorporated herein by reference in its entirety. The thickness of the metallic material that contributes to the formation of the oxygen barrier layer can be varied according to the desired reduction in oxygen permeability.

[0064] For oxygen barrier layers 203 that include polymeric materials, alone or in combination with metallic materials, the melting point of the polymeric material may make placement of the oxygen barrier layer 203 according to one of the placements depicted in Figures 2 to 5 more preferred than the others. A list of exemplary polymeric materials with desired oxygen permeability values ​​is shown in Table 1:

[0065]

[0066] ***from The table was obtained from Dupont-Mistubushi Fluorochemicals Modified.

[0067] Additionally, the polymeric material may include urethanes, such as thermoplastic polyether-urethane (TPEU) or thermoplastic polyester-polyurethane elastomers, as disclosed in US Pat. No. 9,192,754.

[0068] To further reduce the oxygen permeability of the polymeric material, the polymeric material may also be combined with an inorganic additive, such as clay, silicate and silica, layer pillar materials, metal salts, nanosheets or mixtures thereof, such as those described in U.S. Patent Application Publication No. 2010 / 0300571, which is incorporated herein by reference in its entirety. For example, in order to reduce the permeability of the oxygen barrier layer based on the polymeric material, a layered nanofiller may be added to the polymeric material matrix. Such a reduction in permeability may be attributed to the effect of "tortuosity" brought about by the layered nanofiller. This is because oxygen must pass through a much longer path due to these obstacles arranged in successive layers. Theoretical models believe that the barrier effect becomes more pronounced when the aspect ratio, i.e., the ratio of length / width, increases.

[0069] The lamellar nanofillers most extensively studied at present are clays of the smectite type, mainly montmorillonite. The difficulties of use lie firstly in the more or less expensive separation, i.e. exfoliation, of these individual lamellae, and in their distribution within the polymer. To facilitate exfoliation, the "intercalation" technique can be used, which consists in swelling the crystals with organic cations, usually quaternary ammonium cations, which will compensate for the negative charge of the lamellae. These crystalline aluminosilicates exist in the form of individual lamellae when they are exfoliated in a thermoplastic matrix, the aspect ratio of which can reach values ​​of the order of 500 or more.

[0070] According to another aspect of the invention, the inorganic additive may include particles based on zirconium, titanium, cerium and / or silicophosphates in the form of non-exfoliated nano-layered compounds, such as described in U.S. Patent Application Publication No. 2007 / 0082159, the relevant portions of which are incorporated herein by reference.

[0071] The inorganic additive content of the polymeric material used to construct the oxygen barrier layer 203 can vary depending on the desired reduction in oxygen permeability. When present, the inorganic additive can be present in the polymeric material at a weight percentage of 0.01% to about 50% relative to the total weight of the oxygen barrier layer 203 composition.

[0072] Go to Fig. 6A and Figure 6B , a barrier inner tube 608 including a combination of a polymer material and one or more of the inorganic additives described above can be used to construct the hot melt adhesive delivery hose 600. The inorganic additive composition of the polymer material used to construct the barrier inner tube 608 can vary depending on the desired reduction level of oxygen permeability. The inorganic additive can be present in the polymer material at a weight percentage of 0.01% to about 50% with respect to the total weight of the barrier inner tube 608 composition. In a non-limiting example, the barrier inner tube 608 can include a fluoropolymer (e.g., polytetrafluoroethylene) combined with a sufficient amount of one or more of the inorganic additives described above to provide the desired reduction level of oxygen permeability.

[0073] With respect to the placement of the oxygen barrier layer 203 outside the hot zone (e.g., outside the insulating sublayer of the outer layer 106 or outside the protective sublayer of the outer layer 106), any airtight layer will expand and contract due to the expansion of the gas trapped in the insulating layer under the heat applied by the heating belt. To accommodate any thermal expansion, the oxygen barrier layer 203 can be oversized and / or corrugated, or equipped with a one-way valve to allow the expanding gas to escape and subsequently block the entry of oxygen. As described above, placing the oxygen barrier layer 203 outside the hot zone further allows lower melting or softening point materials to be used for this purpose. For example, in addition to the higher melting point materials described above, a metallized polymer film (e.g., aluminized polyester film) can be used outside the hot zone.

[0074] Although not shown, it should be appreciated that Fig. 6A and 6B The transfer hose 600 shown in FIG. 2 may also include a special oxygen barrier layer 203, such as the oxygen barrier layer 203 shown in FIG. 2 to FIG. 5. It should be further recognized that, although the oxygen barrier layer 203 or the barrier inner tube 608 can block or inhibit the ingress of oxygen into the conduit transporting the hot melt adhesive, it may be advantageous to use a low oxygen or inert gas atmosphere during the manufacture of the oxygen barrier layer 203, the barrier inner tube 608 and / or the hot melt adhesive transfer hose.

[0075] Example:

[0076] Standard: To qualitatively evaluate the observed discoloration of Henkel 614C hot melt adhesive in hot melt adhesive delivery tubing, twelve (12) samples of Henkel 614C contained in aluminum sample pans were heated in a laboratory oven at 350°F in ambient atmosphere for 0 to 72 hours. At various intervals, the samples were removed from the oven and allowed to cool to room temperature. The degree of discoloration increased with increasing residence time in the 350°F oven (see Figure 7 ). Based on the graphic representation of 12 samples, Figure 8 A qualitative color scale ranging from a baseline of 1 (for an unheated Henkel 614 sample) to a maximum of 12 (for a sample heated for approximately 95 hours) is illustrated.

[0077] Comparative testing: Multiple samples are evaluated using different pipes with or without any oxygen barrier layer applied. Fig. 9 As shown in the figure, different tubing types include: 0.030" PTFE (resin-based Dupont 62X) core; 0.040" PTFE core with or without stainless steel braid; 0.030" PTFE-lined carbon core with or without stainless steel braid. As in Fig.10 As shown in , the pipe samples without stainless steel braid were sealed with black plastic threaded caps. Multiple pipe and aluminum pan ("ratpan") samples were prepared as described in Table 2 (below) and placed in a laboratory oven (see Fig.11 ) and heated to 350°F for 29 hours. The samples were qualitatively evaluated using the colorimeter established above.

[0078]

[0079]

[0080]

[0081] As in Fig.12 As shown in , the aluminum foil wrapped PTFE inner tube (Sample 1c) provides an improvement in the discoloration of the molten hot melt adhesive under simulated test conditions compared to an uncoated PTFE tube (Sample 1a) or a PTFE tube wrapped with silicone tape (Sample 1b). Although not shown, significant discoloration (e.g., 9 or higher) was still observed for the PTFE tube with an internal carbon coating. In addition, it should be understood that in the case where the color evaluation of the molten hot melt adhesive is monitored in the process, the apparatus and method described in commonly assigned U.S. Patent Application Publication No. 2014 / 0144933 can be utilized, which patent is specifically incorporated herein by reference in its entirety.

[0082] Metal barrier layer

[0083] According to another aspect of the present disclosure, a multi-layer hot melt adhesive delivery hose 700 is provided, the hose 700 being configured to prevent air and other gases from penetrating the hose and contacting the hot melt adhesive therein. Fig.13A and 13B , a hot melt adhesive delivery hose 700 includes a barrier layer including an inner tube 702 configured to prevent oxygen and other gases from entering the conduit of the hose, thereby eliminating discoloration of the molten hot melt adhesive and any associated degradation. In addition, preventing oxygen from entering the hose also maintains the desired "pot life" of the hot melt adhesive.

[0084] Inner tube 702 forms the running core of hose 700, and the hot melt adhesive of melting actually flows through described running core.Inner tube 702 is preferably made of the metal material that can withstand higher temperature, such as stainless steel.In another aspect of the present disclosure, barrier layer can be a metal band, for example aluminum, or the metal coating that is applied to core, as will be discussed in more detail below.Different from the inner tube of conventional hose, the metal inner tube 702 of hot melt adhesive hose 700 is airtight, and therefore does not allow any air to diffuse into the conduit that holds hot melt adhesive.Therefore, the barrier layer that comprises metal inner tube 702 prevents oxygen and other gases from entering hose and forming contact with hot melt adhesive, thus eliminates coking.

[0085] In addition, the metal inner tube 702 blocks moisture from affecting the hot melt PURs and can also keep gases within the hose from escaping. For example, the foamed hot melt within the metal inner tube 702 keeps the gases in solution longer than a standard hose. In addition, because existing hose manufacturing processes can be utilized and / or easily modified, it is more time and cost effective to manufacture an impermeable flexible barrier layer including a metal inner tube according to the present disclosure.

[0086] The inner tube 702 has seamless corrugations to allow flexibility, and preferably maintains a consistent wall thickness throughout the hose to minimize residual stresses in the metal. In addition, the inner tube 702 can be oversized. The inner tube 702 is reinforced by a reinforcement layer or structural layer 704 to help withstand the high fluid pressures used to transport the molten hot melt adhesive. The structural layer 704 disposed around the exterior of the inner tube 702 and used to provide additional strength and protection to the inner tube may include a braided sleeve of a thermally stable material.

[0087] Therefore, structural layer 704 is used to provide the desired physical integrity of the hot melt adhesive transmission hose. In a non-limiting example, structural layer 704 comprises a braided sleeve made of stainless steel. The braiding frequency and / or thickness of the braid can change according to the desired temperature and pressure limit of the hot melt adhesive device. The braid can be a spiral, convoluted, braided / interwoven or annular / annular pattern, such as a square or an independent braid. In addition, the hose 700 may include a plurality of structural layers 704 to provide additional reinforcement for high pressure capability. As shown in Figure 14, a hose 700 with two overlapping structural layers 704, 705 is provided.

[0088] In addition, the hot melt adhesive delivery hose 700 may include a liner 710 disposed on the inner surface of the inner tube 702, such as in Fig.15A and 15B . The liner 710 preferably comprises a thermally stable polymer material, such as polytetrafluoroethylene (PTFE), or other polymers that can withstand higher temperatures. In one aspect of the transmission hose 700, the liner 710 is a special layer that contacts the inner surface of the corrugated inner tube 702. The liner is configured to improve the flow of the hot melt adhesive by minimizing the material incompatibility with the inner tube 702. In particular, the liner 710 has a smooth inner surface to promote fluid flow and prevent the problem of material incompatibility between the medium being transmitted and the metal inner tube 702. For example, the liner 710 prevents material from accumulating in the grooves of the inner corrugated portion of the inner tube 702.

[0089] The hose 700 may further include an outer cover 706. The outer cover 706 may be a multi-layer structure having a heating tape sublayer, an isolation sublayer, and / or a protective sublayer, not shown. The heating tape is used to provide uniform conductive heating to the hot melt adhesive hose. The isolation layer, which may include but is not limited to an aramid felt isolation layer or a fiberglass isolation layer, is used to control heat loss and may also improve chemical resistance and moisture resistance. The protective layer, which is primarily used to protect the hose and other internal components / layers from damage due to physical abuse, may include but is not limited to a durable polymer, such as an aramid jacket.

[0090] Each sublayer of the outer cover is a separate and distinct layer. For example, the heating tape sublayer contacts the outer surface of the structural layer 704 and is covered by the isolation sublayer. The protective sublayer covers the isolation sublayer.

[0091] The heating tape sublayers of the inner tube 702, structural layer 704, and / or outer cover 706 are located in what may be referred to as a "hot zone," which is close to or above the temperature of the molten hot melt adhesive. Alternatively, the outer surface of the insulating or protective sublayer of the outer layer 706 is disposed radially from and outside the hot zone and is therefore subjected to a lower temperature.

[0092] In addition, the transfer hose 700 can be used in a hot melt system that includes a dispenser for dispensing hot melt adhesive onto a substrate. The hose 700 can be operably coupled to the dispenser. The hose can also be operably coupled to a source of liquid hot melt adhesive, such as a melter.

[0093] As described above, the hot melt adhesive is heated to a temperature sufficient to melt the solid form into a molten flowable state, the temperature being generally in the range of about 100°C (about 212°F) to about 230°C (about 450°F). In particular, the transport hose may further include a heater for maintaining the hot melt adhesive at a set point. The heater may include at least one heating wire comprising a metal such as copper, aluminum or silver. The at least one heating wire may be circumferentially wound in a spiral pattern on the outer surface of the inner core of the hose. Alternatively, at least one heating wire may be provided on the outer surface of the inner core along a direction parallel to the longitudinal axis of the inner core.

[0094] The heater is adapted to be electrically coupled to a power source that is controlled to maintain the set point at about 450° F or less for an extended period of time. For example, the flexible metal tube may further transport the hot melt adhesive at a set point temperature of about or less than 400° F, at a set point temperature of about or less than 350° F, or at a set point temperature of about or less than 250° F. A sensor can further be disposed on the heater, or alternatively within the hose, for measuring the set point temperature.

[0095] Additionally, it was observed that the metal barrier layer 702 unexpectedly prevented the hot melt adhesive from charring within the hose 700 at certain temperatures for extended periods of time. In particular, an unknown effect of the barrier layer 702 was observed in which charring of the hot melt adhesive did not occur for at least ninety-six hours when the adhesive was heated to a set point temperature in a range of about or above 250°F up to and including 450°F.

[0096] refer to Fig.16 , row A shows a typical hot melt adhesive in a competitor's hot melt adhesive delivery hose (e.g., Henkel's ), compared to an example of observed color change over time for the hot melt adhesive in the transfer hose 700 of the present disclosure shown in row B. As a comparison standard, the hot melt adhesive was maintained at a set point of 350°F in both the competitor's transfer hose and the transfer hose 700 of the present disclosure. In addition, the color of the adhesive was observed every eight hours for a total period of ninety-six hours.

[0097] As shown, the degree of discoloration of the hot melt adhesive in the competitor's transfer hose increases significantly over time. For example, adhesive sample A9 in the competitor's transfer hose is significantly discolored and contains a large amount of char at ninety-six hours. In contrast, adhesive sample B9 in the transfer hose of the present disclosure is not significantly discolored at ninety-six hours and does not contain a significant amount of char formation. As shown, adhesive sample B9 in the transfer hose of the present disclosure at ninety-six hours has substantially the same color as adhesive sample B1 in the transfer hose of the present disclosure at the beginning.

[0098] In addition, as in Fig.16 As shown in FIG. 1 , the unknown effect of hose 700 is that at eight hours (B2), sixteen hours (B3), twenty-four hours (B4), thirty-two hours (B5), forty hours (B6), forty-eight hours (B7), seventy-two hours (B8), and ninety-six hours (B9), there is no significant discoloration and charring of the adhesive at 350°F in the hose. More specifically, metal barrier layer 702 unexpectedly results in less than 1.0% char formation at 24 hours. Similarly, as shown in FIG. Fig.16 As shown in , the use of the metal barrier layer 702 unexpectedly resulted in less than 1.0% coke formation at 48 hours, 72 hours, and even 96 hours. Fig.16 As shown in the graph, the adhesive on the inside of the competitor's hose showed significant discoloration and charring at eight hours (A2). The severity of discoloration and charring inside the competitor's hose worsened at sixteen hours (A3), twenty-four hours (A4), thirty-two hours (A5), forty hours (A6), forty-eight hours (A7), seventy-two hours (A8), and ninety-six hours (A9).

[0099] Although the disclosure has been illustrated by the description of specific embodiments of the disclosure, and although the embodiments have been described in considerable detail, it is not intended to constrain or in any way limit the scope of the appended claims to such details. The various features discussed herein may be used alone or in any combination. Therefore, the disclosure is not limited to the specific details, representative devices and methods, and illustrative examples shown and described. On the contrary, the disclosure is intended to cover such alternatives, modifications, and equivalent forms without departing from the spirit and scope of application defined by the appended claims.

Claims

1. A multi-layer hot melt adhesive delivery hose, comprising: a flexible metal inner tube for transporting heated liquid hot melt adhesive and forming an impermeable barrier layer configured to prevent oxygen from entering through the flexible metal inner tube and into the heated liquid hot melt adhesive, the flexible metal inner tube forming a running core of the hose through which the heated liquid hot melt adhesive flows, wherein the metal inner tube includes a plurality of seamless corrugations; at least one structural layer configured to withstand fluid pressure; an outer cover, the outer cover covering the outer surface of the at least one structural layer, wherein the outer cover has a multi-layer structure, the multi-layer structure covering, covering and directly contacting the outer surface of the at least one structural layer; and a heater for maintaining a heated liquid hot melt adhesive at a set point, wherein the heater is adapted to be electrically coupled to a power source that is controlled to maintain the set point at or below approximately 450°F for an extended period of time, Wherein, the hose is formed integrally.

2. The hose according to claim 1, wherein The at least one structural layer comprises a braided sleeve.

3. The hose according to claim 2, wherein: The at least one structural layer comprises two overlapping braided sleeves.

4. The hose according to claim 2, wherein: The braided sleeve is made of stainless steel.

5. The hose according to claim 4, wherein: The braided sleeve includes a braid having a spiral pattern, a convoluted pattern, a braided / interwoven pattern, or a circular pattern.

6. The hose according to claim 1, wherein The at least one structural layer is configured to withstand a fluid pressure of up to 10.3 megapascals (MPa).

7. An apparatus for melting and dispensing a hot melt adhesive, the apparatus comprising: a chamber for receiving the hot melt adhesive in solid form; a heating device coupled to the chamber and configured to receive the hot melt adhesive for liquefying the hot melt adhesive in solid form; and The multi-layer hot melt adhesive delivery hose of claim 1, wherein the multi-layer hot melt adhesive delivery hose is fluidly coupled to the heating device.

8. A hot melt system comprising: a dispenser for dispensing the hot melt adhesive onto a substrate; and The hose of claim 1 operatively coupled to a source of liquid hot melt adhesive and to the dispenser.

9. The hot melt system according to claim 8, wherein: The source of liquid hot melt adhesive is a melter.

10. The hose according to claim 1, wherein The impermeable barrier layer includes a metal configured to prevent the ingress of oxygen through the metal inner tube and into the heated liquid hot melt adhesive.

11. The hose according to claim 1, wherein The heater includes a heating wire.

12. The hose according to claim 11, wherein The heating wire is wound circumferentially on an outer surface of one of the following components: the metallic inner tube or the structural layer.

13. A multi-layer hot melt adhesive delivery hose wherein one or more of the layers is an oxygen barrier layer that prevents or minimizes the ingress of oxygen into a conduit of the hose that transports molten hot melt adhesive, in, The multi-layer hot melt adhesive delivery hose comprises: a flexible metal inner tube, the flexible metal inner tube forming the oxygen barrier layer, the oxygen barrier layer being configured to prevent oxygen from entering through the flexible metal inner tube and into the molten hot melt adhesive, the flexible metal inner tube forming a running core of the hose through which the molten hot melt adhesive flows, wherein the metal inner tube includes a plurality of spirally shaped seamless corrugations; a structural layer configured to withstand fluid pressure; and an outer cover, the outer cover covering the outer surface of the structural layer, wherein the metal inner tube conveys molten hot melt adhesive in a molten state, and the metal inner tube has a first inner surface and a first outer surface; wherein the structural layer is arranged to cover the first outer surface of the metal inner tube, and the structural layer has a second inner surface and a second outer surface; and The outer cover is arranged to cover the second outer surface of the structural layer, and the outer cover has a third inner surface and a third outer surface.

14. The hose according to claim 13, wherein The oxygen barrier layer includes a metal layer including aluminum.

15. The hose according to claim 13, wherein The structural layer includes a braided sleeve.

16. The hose according to claim 15, wherein The structural layer comprises two overlapping braided sleeves.

17. The hose according to claim 15, wherein The braided sleeve is made of stainless steel.

18. The hose according to claim 17, wherein The braided sleeve includes a braid having a spiral pattern, a convoluted pattern, a braided / interwoven pattern, or a circular pattern.

19. The hose according to claim 13, wherein: The structural layer is configured to withstand fluid pressures up to 10.3 megapascals (MPa).

20. An apparatus for melting and dispensing a hot melt adhesive, the apparatus comprising: a chamber for receiving the hot melt adhesive in solid form; a heating device coupled to the chamber and configured to receive the hot melt adhesive for liquefying the hot melt adhesive in solid form; and The multi-layer hot melt adhesive delivery hose of claim 13, wherein the multi-layer hot melt adhesive delivery hose is fluidly coupled to the heating device.

21. The hose of claim 13, comprising a heater, the heater comprising a heating wire.

22. The hose according to claim 21, wherein The heating wire is wound circumferentially on an outer surface of one of the following components: the metallic inner tube or the structural layer.

23. A method of dispensing a hot melt adhesive, comprising: molten hot melt adhesive; transporting molten hot melt adhesive to a dispenser via a hose; heating the molten hot melt adhesive in the hose to a set point of about 450°F or less; preventing oxygen transmission to an adhesive within the hose using a barrier layer, wherein the barrier layer comprises a metal inner tube; and dispensing the hot melt adhesive onto a substrate, Wherein, the hose is the hose according to claim 1 or 17.

24. The method according to claim 23, wherein: The set point is approximately 350°F or lower.

25. The method according to claim 23, wherein: The hose includes a heater including a heating wire.

26. The method according to claim 25, wherein: The heating wire is wound circumferentially on an outer surface of one of the following components: the metallic inner tube or the structural layer.

27. A method of transporting a hot melt adhesive, the method comprising: transporting a hot melt adhesive through a flexible metal tube within a multi-layer transfer hose at a temperature at or below a set point of approximately 450° F., wherein the flexible metal tube forms an impermeable barrier layer configured to prevent oxygen from entering the hot melt adhesive, Wherein, the multi-layer transmission hose comprises: the flexible metal tube, the flexible metal tube forming a running core of the hose, through which molten hot melt adhesive flows; a structural layer configured to withstand fluid pressure; and an outer cover, the outer cover covering the outer surface of the structural layer, Wherein, the flexible metal tube comprises a corrugated structure, Wherein, the hose comprises a heater, the heater comprises a heating wire, and The heating wire is circumferentially wound on an outer surface of one of the following components: the flexible metal tube or the structural layer.

28. The method according to claim 27, wherein: The structural layer includes a braided sleeve.

29. The method according to claim 28, wherein: The structural layer comprises two overlapping braided sleeves.

30. The method of claim 28, wherein: The braided sleeve is made of stainless steel.

31. The method according to claim 30, wherein: The braided sleeve includes a braid having a spiral pattern, a convoluted pattern, a braided / interwoven pattern, or a circular pattern.

32. The method of claim 27, wherein: The structural layer is configured to withstand fluid pressures up to 10.3 megapascals (MPa).

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