WO2001053389A1 - Adhesif thermoplastique - Google Patents

Adhesif thermoplastique Download PDF

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Publication number
WO2001053389A1
WO2001053389A1 PCT/US2001/001907 US0101907W WO0153389A1 WO 2001053389 A1 WO2001053389 A1 WO 2001053389A1 US 0101907 W US0101907 W US 0101907W WO 0153389 A1 WO0153389 A1 WO 0153389A1
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WO
WIPO (PCT)
Prior art keywords
thermoplastic material
accordance
thermoplastic
liquid
percent
Prior art date
Application number
PCT/US2001/001907
Other languages
English (en)
Inventor
William C. Stumphauzer
Original Assignee
Illinois Tool Works, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Illinois Tool Works, Inc. filed Critical Illinois Tool Works, Inc.
Priority to AU2001229664A priority Critical patent/AU2001229664A1/en
Publication of WO2001053389A1 publication Critical patent/WO2001053389A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
    • C08J3/09—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in organic liquids
    • C08J3/091—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in organic liquids characterised by the chemical constitution of the organic liquid
    • C08J3/095—Oxygen containing compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/02—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface
    • B05C11/023—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface
    • B05C11/028—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface with a body having a large flat spreading or distributing surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/10—Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material
    • B05C11/1002—Means for controlling supply, i.e. flow or pressure, of liquid or other fluent material to the applying apparatus, e.g. valves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/10—Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material
    • B05C11/1002—Means for controlling supply, i.e. flow or pressure, of liquid or other fluent material to the applying apparatus, e.g. valves
    • B05C11/1007—Means for controlling supply, i.e. flow or pressure, of liquid or other fluent material to the applying apparatus, e.g. valves responsive to condition of liquid or other fluent material
    • B05C11/1013—Means for controlling supply, i.e. flow or pressure, of liquid or other fluent material to the applying apparatus, e.g. valves responsive to condition of liquid or other fluent material responsive to flow or pressure of liquid or other fluent material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/10—Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material
    • B05C11/1042—Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material provided with means for heating or cooling the liquid or other fluent material in the supplying means upstream of the applying apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
    • B05C5/001—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work incorporating means for heating or cooling the liquid or other fluent material
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
    • C08J2327/06—Homopolymers or copolymers of vinyl chloride

Definitions

  • the present invention pertains to a thermoplastic adhesive.
  • the present invention pertains to a thermoplastic adhesive that is flowable at room temperature, and remains flowable through heat-up, up to and at application temperature.
  • the invention further pertains to an apparatus for applying such a thermoplastic adhesive.
  • Hot melt adhesives are widely used in most every industry today. These adhesives are used to bond together a broad ranges of substrates and products.
  • One advantage of hot melt adhesives is that they solidify rapidly to create functional adhesive bonds generally within seconds of being dispensed from a hot melt applicator.
  • hot melt adhesives are 100% solids thermoplastics that are solid at room temperature and become flowable liquids at elevated temperatures. These temperatures typically range from about 300°F to about 400°F, within which range the adhesives are sufficiently flowable to be expelled from applicator equipment. When applied as a hot liquid to a substrate, heat is rapidly drawn from the hot melt by the bonded substrate. Thus, rapid solidification of the hot melt occurs and a relatively fast adhesive bonding of the substrates results.
  • hot melts can be specifically formulated for use as caulks, sealants and gasket materials. These materials have the desirable characteristic, vis-a-vis these particular applications, in that they become almost immediately functional because they solidify quickly after being dispensed as a molten liquid.
  • Hot melt adhesives may also be formulated and dispensed as foams providing the further advantage of forming compressible seals with insulative and acoustic attenuation properties.
  • hot melts do not provide a wide range of application possibilities when applied as foams.
  • Hot melt adhesives do, however, have their drawbacks.
  • this equipment includes melting and holding tanks, heated pumps, heated hoses and heated dispensing heads.
  • the equipment requires expensive and extensive maintenance in order to assure proper functionality.
  • the adhesive must be maintained at a sufficiently elevated temperature in order to remain in a liquid state.
  • significant operating costs are encountered due to the heat consumption of the equipment necessary to maintain the adhesive in a liquid state.
  • the equipment must be maintained at elevated temperatures, it has been found that the costs associated with parts replacement can become a considerable part of the overall operating costs for this type of system.
  • hot melt adhesives which flow readily at temperatures of about 300°F to 350°F, have relatively low molecular weights compared to higher molecular weight compositions that are melted in extruders (at temperatures of about 425°F to 550°F). These low molecular weight thermoplastics are not as strong as the higher molecular weight extruded materials. As such, lesser performance characteristics can include lower tensile strength, lower elongation before break, low tensile modulus, and less compression set resistance. To this end, most hot melt adhesives are generally not particularly well-suited for high performance bonds, caulks, sealants or gaskets. In addition, the physical properties of hot melt adhesives decrease significantly when applied as a foam. In fact, the cross-sectional strength, tensile, modulus and compression set characteristics have been shown to decrease such that hot melt adhesive foams have extremely limited functional utility.
  • hot melt adhesives form functional adhesive bonds quickly upon application, they are used extensively in high-speed production lines.
  • hot melt adhesives are used for consumer packaging and bonding of paper products such as cartons, boxes, corrugated cases, non- woven products and the like.
  • cold glues for use in consumer packaging applications.
  • these cold glues are liquid emulsion adhesives that set and cure by the removal (e.g., evaporation and/or substrate absorption) of water from the emulsion.
  • water is the primary carrier liquid for the emulsion.
  • these adhesives do not provide the adhesive strength almost immediately upon dispensing as compared to hot melt adhesives. This is due in part to the necessity for the removal of water from the liquid emulsion in order to form these bonds. As such, high-speed production cannot be achieved using these cold glues.
  • radio frequency dielectric heating in which electromagnetic fields in the range of about 10 to about 20 megahertz (MHz) has been attempted.
  • the application of the radio wave frequencies heats the emulsions and evaporates water through the excitation of the polar water molecules.
  • This process also requires considerable amounts of energy because of the water that must be evaporated from the emulsion for the adhesive to set.
  • high concentrations of radio frequency power are required. It has been found that these high concentrations of radio frequency power also heat the underlying substrate, e.g., paperboard packaging, and may heat the substrate to temperatures sufficiently high to cause discoloration and possible combustion of the substrate product.
  • plastisol Another type of adhesive, commonly known as plastisol is a resin suspension, typically of polyvinyl chloride (PVC) resin in plasticizers that are liquid at room temperature and fused to a 100% solids thermoplastic when heated to about 325°F to about 375°F and subsequently cooled to at a solid at room temperature.
  • PVC polyvinyl chloride
  • plasticizers typically of polyvinyl chloride (PVC) resin in plasticizers that are liquid at room temperature and fused to a 100% solids thermoplastic when heated to about 325°F to about 375°F and subsequently cooled to at a solid at room temperature.
  • plastisols are used for nylon coating, linoleum top coating, carpet backing and bonding to aluminum, glass, fabric, and sheet metal.
  • plastisols work well for their intended purpose, they are typically not used as adhesives for high speed bonding of, for example, paper products or packaging. Plastisols are not used in this type of bonding scenario in that it has been found to be quite difficult to heat them from room temperature liquids to molten thermoplastic adhesives in the short time available (seconds or milliseconds) required for high-speed bonding processes.
  • plastisols are typically unusable in conventional hot-melt applicator equipment. During use this equipment may maintain the adhesive material at elevated temperatures (e.g., above about 300°F to 350°F) for prolonged and unpredictable periods of time. When subjected to these longer periods of elevated temperatures, plastisols become unstable and degrade. Once degradation begins, it can rapidly accelerate throughout the material. Thus, because conventional hot-melt applicators cannot limit or control the heat history of the materials used therein, these applicators are not well suited for applying plastisol materials.
  • plastisols do not proceed through physical phase changes in the same manner as hot-melt adhesives.
  • hot-melt materials are heated, they go through typical phase changes from solid to softening to liquid, with viscosity decreasing throughout heating.
  • plastisols which are liquid at room temperature, are heated, the viscosity decreases.
  • the composition converts to a solid (referred to as a gel).
  • fusion temperature and above about 300°F to 350°F
  • plastisols become a highly viscous molten thermoplastic.
  • the phase change as heated from liquid to solid to unstable viscous liquid makes these compositions unsuitable for use in conventional hot-melt application equipment.
  • thermoplastic adhesive that is flowable at room temperature and attains its adhesive properties after it cools from an elevated temperature.
  • such an adhesive remains flowable from room temperature through heat-up, up to and at application temperature.
  • thermoplastic adhesive can be heated quickly for use as a molten adhesive with rapid set bonding characteristics similar to those of hot-melt adhesives.
  • a heat-activated thermoplastic material for forming an adhesive is an admixture of a thermoplastic resin in a liquid carrier.
  • the admixture is a liquid slurry at room temperature that undergoes a change in which the slurry becomes pasty upon heating to a fusion temperature and liquefies upon further heating to form a pumpable molten liquid.
  • the molten liquid hardens as it cools to form an adhesive.
  • the cooled, hardened adhesive being reheatable to return to a liquid state.
  • thermoplastic resin is a copolymer of polyvinyl chloride and vinyl acetate.
  • polyvinyl chloride is present in the thermoplastic resin in a concentration of about 85 percent and vinyl acetate is present in a concentration of about 15 percent, and the thermoplastic resin has a relative viscosity of less than about 1.8.
  • the thermoplastic resin is a copolymer of polypropylene or polyethylene.
  • the carrier liquid can be a non-volatile liquid such as diisodecyl phthlate, diisodecyl adipate, dinonyl phthlate, dioctyl phthlate, tricresyl phosphate and dioctyl adipate.
  • the carrier liquid is diisodecyl phthlate.
  • the thermoplastic resin is present in a concentration of about 60 percent by weight of the slurry, and the carrier liquid is present in a concentration of about 40 percent by weight of the slurry.
  • the thermoplastic material can include additives, such as carbon fiber, calcium carbonate, stabilizers, wetting agents, tackifiers, foaming agents or plasticizers. Small amounts of ground hot-melt adhesive can also be added to the material to improve the adhesion characteristics.
  • the thermoplastic material includes electromagnetic receptor particles admixed with the thermoplastic resin and the liquid carrier.
  • the receptor particles can be ferromagnetic particles, zinc oxide, fumed silica, magnesium aluminum silicate, graphite, carbon black or conductive metal powder.
  • the liquid carrier can be a thermally conductive liquid.
  • the thermally conductive liquid is formed from polar molecules and the thermoplastic resin is formed from polar molecules.
  • the receptor particle containing formulation can be heated by a high frequency electromagnetic field.
  • An apparatus for dispensing and activating the receptor particle containing heat-activated thermoplastic material includes a reservoir or tank for storing the heat-activated thermoplastic material when in a liquid state and a nozzle for dispensing the heat activated thermoplastic material when in a liquid state.
  • the apparatus further includes an electromagnetic field generator for generating an electromagnetic field.
  • the generator is disposed downstream of the nozzle so that the electromagnetic field acts on the heat activated material after it is dispensed from the nozzle.
  • the material becomes pasty upon heating to a fusion temperature and liquefies upon further heating to form a pumpable molten liquid.
  • the molten liquid hardens as it cools to form an adhesive.
  • the cooled, hardened adhesive being reheatable to return to a liquid state.
  • the apparatus can includes a pump disposed between the tank and the nozzle for conveying the heat-activated thermoplastic material from the tank to the nozzle.
  • a dispensing valve can be disposed between the tank and the nozzle for commencing and terminating flow of the heat-activated thermoplastic material.
  • the dispensing valve can be disposed between the pump and the nozzle.
  • the apparatus can further include a mixer disposed between the dispensing valve and the pump.
  • the electromagnetic field generator can be a coil.
  • FIG. 1 is a schematic illustration of one embodiment of an apparatus for dispensing and activating a heat activated thermoplastic embodying the principles of the present invention
  • FIG. 2 is a schematic illustration of an alternate embodiment of a dispensing and activating apparatus embodying the principles of the present invention
  • FIG. 3 is a still another embodiment of the dispensing and activating apparatus
  • FIG. 4 is a graphical representation of the molten or liquid viscosity along the abscissa measured in centipoise at 350°F as a function of the plasticizer concentration shown along the ordinate in a concentration of part per hundred resin (PHR), illustrated at various constant resin relative viscosities; and
  • FIG. 5 is a graphical representation of the molten or liquid viscosity along the ordinate measured in centipoise at 350°F as a function of varying plasticizer levels in PHR shown along the abscissa, for three different resins having different relative viscosities.
  • thermoplastic adhesive in accordance with the principles of the present invention is a flowable liquid at room temperature and remains flowable at elevated temperatures up to application temperature.
  • thermoplastic adhesive in accordance with the present invention is a flowable liquid at room temperature that can be reheated and re-liquefied (to a flowable liquid) after it has solidified. In this manner, no heating of the adhesive storage and transport or conveying equipment is required.
  • thermoplastic adhesive as a liquid
  • the thermoplastic adhesive can be heated immediately prior to dispensing, for example, by a heater located at the dispensing head.
  • the liquid can be heated quickly, generally, within about two seconds, thus facilitating use in high speed processing lines such that as that used in packaging of consumer goods using paperboard and like substrate packaging.
  • the thermoplastic adhesive is a suspension of thermoplastic resin in a liquid.
  • the liquid is a thermally conductive liquid.
  • electromagnetic receptor particles are also suspended within the liquid.
  • the liquid carrier may be a plasticizer, such as diisodecyl phthlate (DIDP), diisodecyl adipate (DID A), dinonyl phthlate (DNP), dioctyl phthlate (DOP), tricresyl phosphate (TCP), dioctyl adipate (DOA) and the like.
  • DIDP diisodecyl phthlate
  • DID A diisodecyl adipate
  • DNP dinonyl phthlate
  • DOP dioctyl phthlate
  • TCP tricresyl phosphate
  • DOA dioctyl adipate
  • the thermoplastic resin suspended in the liquid may be, for example, a polyvinyl chloride (PVC) dispersion resin, such as GEON 137, which is a functionally reactive copolymer resin that includes carboxyl functional groups, and which is commercially available from PolyOne Corporation (GEON) of Avon Lake, Ohio.
  • PVC polyvinyl chloride
  • GEON PolyOne Corporation
  • the thermoplastic resin is a highly polar molecule. It has been found that polar molecules can move more freely in liquids. It has also been found that these highly polar molecules, when exposed to high frequency magnetic fields, tend to rapidly twist and reorient themselves in accordance with the electromagnetic fields. This twisting and reorienting motion produces heat within the adhesive.
  • polar thermoplastic molecules exhibit superior adhesion to non-polar substrates such as coated paperboard and the like.
  • the thermally conductive liquid is also formed from polar molecules. Examples of such polar liquids include the above- noted DOA and TCP.
  • thermoplastic adhesive admixing and suspending the electromagnetic receptor particles within the thermally conductive liquid can greatly increase the heat-up rate of the thermoplastic adhesive.
  • two sources of heat generation are created, namely, dielectric and induction heating.
  • Induction heating is produced when the high frequency electromagnetic fields cause electrical currents to flow in and through the conductive particles that, because of their physical size, resist the current flow. The resistance to current flow results in heat-up of the particles due to the flow of electrical current. This heat is rapidly absorbed by the plasticizer and is believed to synergistically act to accelerate the dielectric heating rate.
  • the increased temperature of the plasticizer in turn increases the vibration rate of the polar molecules so that they are more responsive to the high frequency electromagnetic fields.
  • this increased temperature resulting in increased heat
  • the polar PVC molecules are free to reorient and twist which, in turn, produces frictional heat in response to the high frequency electromagnetic fields.
  • thermoplastic adhesive in accordance with the principles of the present invention.
  • the rate of heat-up of the liquids with simultaneous dielectric and induction heating was at least 5.5 times faster than the rate of heat-up by dielectric heating alone.
  • the microwave energy of this example was not optimized for use in heating or fusion melting plastisols of the present invention. Specifically, the microwave energy was not focused into a single mode which would otherwise produce more intense and rapid heating. It must also be recognized that the reflection of microwave energy off of the oven walls caused some of the microwaves to be cancelled while others were amplified and some possible absorbed by the magnetron element of the microwave oven. The actual time to achieve fusion melting of plastisol with the receptors admixed therein will, likely, be far less than that shown when the radio frequency energy is focused into a single mode and optimized for this particular purpose.
  • the above-noted electromagnetic receptor particles are known in the art. Typically, these receptor particles heat-up when they are exposed to high frequency electromagnetic fields. Generally, the heat-up is optimized when the receptor particles are exposed to electromagnetic fields within a specific frequency range.
  • Electromagnetic field generators are also known in the art.
  • One example of such a generator is, as set forth above, a conventional, household microwave oven.
  • Other generators include power supplies that are readily available today. The range of frequencies produced by these field generators, their power output and electronic circuitry all effect the size and cost of the specific generator.
  • Table 2 below provides a comparison of various, exemplary electromagnetic receptor particles and electromagnetic field generators and approximate costs for operating these generators.
  • thermoplastic adhesive is in high speed case sealing in which corrugated boxes are formed and sealed at their flaps.
  • unsealed cases are conveyed past an adhesive dispensing head that extrudes a room temperature thermoplastic adhesive on to the case flaps.
  • the flaps are then folded down and held in compression against their mating flaps until the adhesive is activated by a high frequency electromagnetic field.
  • the adhesive becomes a fuse-melted thermoplastic that solidifies upon cooling thus bonding the flaps to one another.
  • the room temperature thermoplastic may be passed through a high frequency electromagnetic field source that heats and fuse melts the room temperature thermoplastic adhesive as it is being dispensed onto the case flaps.
  • One presently known method to seal cases is one in which a hot melt adhesive is applied to the case flaps.
  • An exemplary high speed case sealer operates to seal the flaps on forty cases measuring 20"x 20" x 20". This corresponds to about 1.1 feet per second of thermoplastic adhesive application.
  • Typical adhesive coverage is about 80% of the length of two of the four box flaps.
  • each adhesive dispensing head extrudes an adhesive bead measuring about 0.040 inches (40 mils) high and 0.100 inches wide (100 mils) and 16 inches in length in about 1.5 seconds.
  • adhesive deposition flow rates can vary greatly. Nevertheless, a properly calibrated dispensing head extrudes about 120 milligrams of adhesive per inch. This results in about 1.92 grams of adhesive dispensed in 1.5 seconds or about 1.26 grams of adhesive per second.
  • thermoplastic adhesive in accordance with the present invention was subjected to electromagnetic energy to determine the heat-up time and to determine the temperature based upon a given power output. It was found that a equivalent temperature rise of 660°F per gram per second PVC suspension was achieved. The preferred temperature rise is based upon raising 200 grams by 200°F in 75 seconds. It was further found that fusion melting of 1 gram of PVC resin suspension was achieved in about 2.5 seconds using a 1 kilowatt induction power supply commercially available from Ameritherm of Scottsville, New York under equipment model no. 1M NOVASTAR.
  • the PVC resin suspension contained a 10% by weight concentration of 100 micron particle size ferromagnetic powder.
  • thermoplastic adhesive of the present invention can also be used to generate foams with blowing agents that activate when the PVC suspensions reach fusion melting temperatures.
  • foaming agents that activate when the PVC suspensions reach fusion melting temperatures.
  • PVC thermoplastic adhesive costs can be reduced by as much as 70%.
  • One such foaming agent is azodicarbonamide (1-1'- azobisformamide) which is a temperature sensitive foaming agent.
  • This and other foaming agents are commercially available under the name CELOGEN® from Uniroyal Chemical Company, Inc. of Middlebury, Connecticut.
  • FIG. 1 An exemplary apparatus 10 for applying a thermoplastic adhesive in accordance with the present invention is illustrated in FIG. 1.
  • the apparatus 10 includes a storage reservoir such as the illustrated tank 12.
  • the liquid L is stored in the tank 12 and is transferred by a pump 14.
  • the liquid L is drawn by a siphon tube 16 into the pump 14.
  • the liquid L is discharged from the pump 14 through an optional mixer 18 and into a dispensing valve 20.
  • a recirculation line 22 can return undispensed liquid L back to the pump 14 inlet.
  • the liquid L is extruded through a nozzle 24 when the dispensing valve 20 is opened.
  • the dispensing valve 20 is controlled by a valve actuator 26 that is controlled by a signal from a speed and flow responsive controller 28.
  • the liquid L passes through a high frequency electromagnetic field that is generated by an emitter 30.
  • the emitter 30 is in a fixed relationship relative to the valve 20 and is actuated by a power supply 32.
  • the liquid L is heated from room temperature to the fusion temperature, at which it changes or converts to a molten thermoplastic.
  • the molten thermoplastic is deposited onto a substrate S, such as the exemplary carton flaps to provide an application of thermoplastic adhesive A.
  • the thermoplastic adhesive A can be deposited to form a gasket.
  • the thermoplastic adhesive A solidifies as it cools to room temperature.
  • the controller 28 can be configured to receive a signal from a flow sensor 34 when the dispensing valve 20 is opened and the liquid L is flowing through the nozzle 24. In this manner, the emitter 30 will only require energy when the flow sensor 34 provides a signal to the controller 28 that liquid L is flowing.
  • the sensor 34 can provide information such as the mass flow of liquid L to the controller 28 and power supply 32, so that the power output and/or frequency of the power supply 32 can be accordingly proportioned to the flow of liquid L.
  • a motion sensor 36 can also be used to provide information regarding the movement of the substrate S to the controller 28 and pump controller for adjusting the liquid L output.
  • the emitter 130 can be positioned downstream of the dispensing valve 120 rather than at the valve 120.
  • the liquid L converts to a molten thermoplastic as it enters the magnetic field downstream of the nozzle 124 and dispensing valve 120, rather than in close proximity to the valve 120 and nozzle 124.
  • this arrangement provides a benefit in that the heating location, and thus the location at which the liquid L is subjected to electro-magnetic energy (to progress through the phases of room temperature liquid to molten liquid) is displaced from any of the liquid transport systems.
  • the opportunity for the adhesive A to solidify within any of the transport systems is greatly reduced and perhaps fully eliminated.
  • FIG. 3 illustrates an arrangement in which a sealing member
  • SI e.g., a box flap
  • the liquid L is dispensed on to the substrate S, prior to being subjected to the electromagnetic field.
  • the flaps S, SI being folded on to one another, the entire structure is subjected to the electromagnetic field and the thermoplastic adhesive A then takes on its adhesive properties.
  • thermoplastic adhesive is a liquid slurry at room temperature that, upon heating, undergoes a reaction in which the liquid becomes pasty and, subsequently, upon further heating liquefies. In all states, until it cools to form an adhesive, the thermoplastic adhesive remains sufficiently liquid that it is pumpable. As the thermoplastic adhesive cools from its fusion or activation temperature, it hardens to provide extremely good adhesive properties.
  • the hardened adhesive can be reheated to return to a liquid state.
  • the slurry is an admixture of generally, a thermoplastic resin and a plasticizer.
  • a preferred thermoplastic resin is a copolymer of polyvinyl chloride (PVC) and vinyl acetate (VA).
  • the copolymer is suspended in a liquid carrier, such as diisodecyl phthalate (DIDP).
  • DIDP diisodecyl phthalate
  • the PVC is present in a concentration of about 70 percent to about 95 percent of the resin and the VA is present in a concentration of about 30 percent to about 5 percent of the resin.
  • the PVC is present in a concentration of about 85 percent by weight of the copolymer and the VA is present in a concentration of about 15 percent by weight of the copolymer.
  • the aggregate of the copolymer in the slurry is about 60 percent by weight of the slurry.
  • standard molecular weights e.g., from standard relative viscosities (RVs) of about 2.0. to 2.5 to a RV of about 1.8 or below
  • RVs relative viscosities
  • the suspensions do not solidify when heated. This is in contrast to plastisols which, as set forth above, solidify to a gel when heated and upon further heating fuse to become highly viscous, unpumpable melts.
  • one of the constituents of the copolymer is vinyl acetate (VA)
  • VA vinyl acetate
  • the relative viscosity (RV) of a polymer is one measure of the molecular weight of that polymer; essentially, the relative viscosity is proportional to the molecular weight, and is a critical function that influences the physical change characteristics as the material is heated.
  • RV relative viscosity
  • a lower molecular weight results in a lower molten or liquid viscosity at fusion temperature.
  • the fusion temperature is assumed to be about 300°F to 350°F.
  • the molten viscosity likewise increases.
  • thermoplastic adhesive having characteristics similar to hot-melt adhesives, has a plasticizer level below about 120 PHR and an RV less than or equal to about 1.8.
  • a present formulation of the adhesive uses a copolymer having a relative viscosity of about 1.58, as equivalent to ASTM D-1243 standards for inherent viscosity.
  • the RV of the copolymer is a function of the molecular weight, e.g., the chain length of the copolymer.
  • the liquid viscosity (as it varies though the entire application temperature range), although not critical, is important for the specific use as an adhesive. This is to assure that the adhesive (prior to cooling and solidification) remains pumpable throughout the heat-up range.
  • the liquid viscosity is also important in that it is a function of the plasticizer concentration, i.e., PHR and the copolymer RV.
  • a desired liquid viscosity of the molten liquid at fusion temperature is as shown in FIG. 4 in the zone indicated at R.
  • the adhesive achieves the desired adhesive properties upon activation and subsequent cooling and is within a liquid viscosity range in which it remains pumpable from room temperature through heat up.
  • Other characteristics of the resin e.g., particle size, can also affect pumpability.
  • thermoplastic resin can be formed of, in addition to a copolymer of PVC and VA, copolymers of PVC and ethylene vinyl acetate (EVA), copolymers of polyethylene or polypropylene and VA, copolymers of polyethylene or polypropylene and EVA, copolymers of PVC and olefins, copolymers of PVC and acrylonitrile, and copolymers of polyethylene or polypropylene and ethylene acrylic acid (EAA).
  • EAA ethylene vinyl acetate
  • thermoplastic resin can be formed of various homopolymers, such as PVOH, various terpolymers, such as a PVA/VA terpolymer having a grafted functional acid group, such as acrylic or maleic acid, acrylonitrile-butadiene-styrene (ABS) the like.
  • a terpolymer of PVC/V A/acrylic acid having a concentration of about 1 percent to about 5 percent of the acid group by weight of the terpolymer has been shown to exhibit increased adhesive characteristics.
  • Such other polymers will be recognized by those skilled in the art.
  • the DIDP functions as a plasticizer to form a part of the adhesive. In this manner, it is a non-volatile carrier. That is, it is not driven off by heating the liquid adhesive; rather, it becomes part of the adhesive.
  • non-volatile carrier liquids include, for example, diisodecyl phthlate (DIDP), diisodecyl adipate (DID A), dinonyl phthlate (DNP), dioctyl phthlate (DOP), tricresyl phosphate (TCP), dioctyl adipate (DOA) and the like.
  • DIDP diisodecyl phthlate
  • DID A diisodecyl adipate
  • DNP dinonyl phthlate
  • DOP dioctyl phthlate
  • TCP tricresyl phosphate
  • DOA dioctyl adipate
  • water can be used as a carrier, in which case, the water will function as a volatile carrier, in that it will likely be driven off by heating the liquid to fusion temperature.
  • additives can be included in the material such as carbon fiber, or other reinforcements, fillers such as calcium carbonate, stabilizers, wetting agents, tackifiers, plasticizers and the like.
  • fillers such as calcium carbonate, stabilizers, wetting agents, tackifiers, plasticizers and the like.
  • powdered or finely ground particles of conventional hot-melt adhesive can be added to the liquid adhesive slurry in some instances.
  • foaming agents such as azodicarbonamide and the like can be added to create a foamed adhesive.
  • thermoplastic adhesive is a slurry of a copolymer of
  • sample 1 was a PVC/VA copolymer commercially available from Vinnolit GmbH & Co. KG, of Ismaning, Germany under the trademark VINNOLIT C 14/50 V.
  • Samples 2 and 3 were PVC/VA copolymers commercially available from Wacker Polymer Systems of Adrian, Michigan, under the trademarks VINNOL 15/45 and VINNOL 40/43, respectively.
  • compositions also included in each of the compositions was a stabilizer at a concentration of about 12 parts per hundred resin and fumed silica at a concentration of about 2 parts per hundred resin.
  • a stabilizer at a concentration of about 12 parts per hundred resin
  • fumed silica at a concentration of about 2 parts per hundred resin.
  • thermoplastic adhesive in accordance with the principles of the present invention can be formulated from certain mixtures (e.g., mechanical mixtures) of homopolymers such as PVOH, VA, EVA, EAA, PVC, and polyethylene and polypropylene homopolymers and the like.
  • the plasticizers discussed above e.g., DIDP, DID A, DNP, DOP, can be used as carrier liquids for such polymer mixtures, as will be recognized by those skilled in the art.
  • volatile carrier liquids such as water, can be used for the mechanically mixed resins.
  • thermoplastic adhesive of the present invention result from the low molecular weight characteristics of the resin used, in combination with the plasticizer as a carrier liquid. This is seen even with lower than would be expected levels of plasticizer. To this end, it has been found that the present thermoplastic adhesive remains in a liquid state through heat-up to about 350°F. It is theorized that if high plasticizer levels were in fact needed and used, once cooled, the adhesive would be too soft and gummy to be useful as an adhesive.
  • heating can be carried out using a simplified heated dispensing head.
  • the heat or energy can be provided by an electric heating coil, a steam heater, or by heated air that is provided to the head.
  • Such a heating arrangement is possible because of the unique characteristics of the adhesive being a liquid at room temperature and remaining a pumpable liquid through heat up to application temperature.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Adhesives Or Adhesive Processes (AREA)

Abstract

L'invention concerne une matière thermoplastique thermocollante conçue pour former un adhésif, qui est fabriquée à partir d'un mélange d'une résine thermoplastique dans un excipient liquide. Le mélange est une suspension épaisse à température ambiante qui subit une modification pendant laquelle la suspension devient pâteuse lorsqu'elle est chauffée à une température de fusion puis se liquéfie lorsqu'elle est chauffée davantage pour former un liquide fondu pompable. Le liquide fondu durcit lors du refroidissement pour former un adhésif. L'adhésif refroidi, durci peut être réchauffé pour retourner à l'état liquide. L'invention concerne également un appareil permettant d'appliquer l'adhésif.
PCT/US2001/001907 2000-01-19 2001-01-19 Adhesif thermoplastique WO2001053389A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001229664A AU2001229664A1 (en) 2000-01-19 2001-01-19 Thermoplastic adhesive

Applications Claiming Priority (2)

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US17706700P 2000-01-19 2000-01-19
US60/177,067 2000-01-19

Publications (1)

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WO2001053389A1 true WO2001053389A1 (fr) 2001-07-26

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004016346A1 (de) * 2004-04-02 2005-10-20 Fraunhofer Ges Forschung Verfahren und Vorrichtung zum dosierten Abscheiden kleinster Mengen von viskosem Material auf einer Oberfläche sowie Dosiervorrichtung
US7285583B2 (en) 2002-07-30 2007-10-23 Liquamelt Licensing Llc Hybrid plastisol/hot melt compositions
US7456233B2 (en) 2005-02-16 2008-11-25 Nordson Corporation Adhesive composition
DE102009045861A1 (de) 2009-10-20 2011-04-21 Henkel Ag & Co. Kgaa Verfahren zur Durchführung einer Phasenumwandlung
EP2684615A1 (fr) * 2012-07-13 2014-01-15 Nordson Corporation Système de distribution d'adhésif ayant un système de dosage comprenant un entraînement à fréquence variable et une commande de rétroaction en boucle fermée
US11365296B2 (en) * 2017-09-15 2022-06-21 Heedae Park Nanosilica-containing thermoplastic hot-melt film having excellent bonding strength

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3632021A (en) * 1969-02-13 1972-01-04 John Macmanus Apparatus for making and dispensing aerated food products
US3717875A (en) * 1971-05-04 1973-02-20 Little Inc A Method and apparatus for directing the flow of liquid droplets in a stream and instruments incorporating the same
US4338227A (en) * 1980-09-05 1982-07-06 E. I. Du Pont De Nemours And Company Ethylene copolymer blends and adhesives based thereon
US4391853A (en) * 1979-12-10 1983-07-05 The Datak Corporation Methods of making adhesive articles and resulting products
US4540037A (en) * 1982-09-27 1985-09-10 Concast Ag Method and apparatus for bidirectional horizontal continuous casing
US5143961A (en) * 1987-06-29 1992-09-01 H. B. Fuller Licensing & Financing Inc. Hot melt adhesive comprising water soluble polyalkyloxazoline and water insoluble polymer

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3632021A (en) * 1969-02-13 1972-01-04 John Macmanus Apparatus for making and dispensing aerated food products
US3717875A (en) * 1971-05-04 1973-02-20 Little Inc A Method and apparatus for directing the flow of liquid droplets in a stream and instruments incorporating the same
US4391853A (en) * 1979-12-10 1983-07-05 The Datak Corporation Methods of making adhesive articles and resulting products
US4338227A (en) * 1980-09-05 1982-07-06 E. I. Du Pont De Nemours And Company Ethylene copolymer blends and adhesives based thereon
US4540037A (en) * 1982-09-27 1985-09-10 Concast Ag Method and apparatus for bidirectional horizontal continuous casing
US5143961A (en) * 1987-06-29 1992-09-01 H. B. Fuller Licensing & Financing Inc. Hot melt adhesive comprising water soluble polyalkyloxazoline and water insoluble polymer

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7285583B2 (en) 2002-07-30 2007-10-23 Liquamelt Licensing Llc Hybrid plastisol/hot melt compositions
US7501468B2 (en) 2002-07-30 2009-03-10 Liquamelt Corp. Adhesive composition
US7772313B2 (en) 2002-07-30 2010-08-10 Liquamelt Corp. Pumpable heat-processable liquid dispersions for forming fused thermoplastic solids
DE102004016346A1 (de) * 2004-04-02 2005-10-20 Fraunhofer Ges Forschung Verfahren und Vorrichtung zum dosierten Abscheiden kleinster Mengen von viskosem Material auf einer Oberfläche sowie Dosiervorrichtung
DE102004016346B4 (de) * 2004-04-02 2007-07-12 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren und Vorrichtung zum dosierten Abscheiden kleinster Mengen von viskosem Material auf einer Oberfläche sowie Dosiervorrichtung
US7456233B2 (en) 2005-02-16 2008-11-25 Nordson Corporation Adhesive composition
DE102009045861A1 (de) 2009-10-20 2011-04-21 Henkel Ag & Co. Kgaa Verfahren zur Durchführung einer Phasenumwandlung
WO2011047962A2 (fr) 2009-10-20 2011-04-28 Henkel Ag & Co. Kgaa Procédé de mise en oeuvre d'un changement de phase
WO2011047962A3 (fr) * 2009-10-20 2011-06-23 Henkel Ag & Co. Kgaa Procédé de mise en oeuvre d'un changement de phase
EP2684615A1 (fr) * 2012-07-13 2014-01-15 Nordson Corporation Système de distribution d'adhésif ayant un système de dosage comprenant un entraînement à fréquence variable et une commande de rétroaction en boucle fermée
US9296009B2 (en) 2012-07-13 2016-03-29 Nordson Corporation Adhesive dispensing system having metering system including variable frequency drive and closed-loop feedback control
US11365296B2 (en) * 2017-09-15 2022-06-21 Heedae Park Nanosilica-containing thermoplastic hot-melt film having excellent bonding strength

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