Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
  • C09K3/1006—Materials in mouldable or extrudable form for sealing or packing joints or covers characterised by the chemical nature of one of its constituents
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/46—Polymerisation initiated by wave energy or particle radiation
  • C08F2/48—Polymerisation initiated by wave energy or particle radiation by ultraviolet or visible light
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/10—Esters
  • C08F220/34—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate
  • C08F220/343—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate in the form of urethane links
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F222/00—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 carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides, or nitriles thereof
  • C08F222/10—Esters
  • C08F222/1006—Esters of polyhydric alcohols or polyhydric phenols
  • C08F222/106—Esters of polycondensation macromers
  • C08F222/1065—Esters of polycondensation macromers of alcohol terminated (poly)urethanes, e.g. urethane(meth)acrylates
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
  • C08K5/549—Silicon-containing compounds containing silicon in a ring
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
  • C09D175/04—Polyurethanes
  • C09D175/06—Polyurethanes from polyesters
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on 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 only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
  • C09J175/04—Polyurethanes
  • C09J175/14—Polyurethanes having carbon-to-carbon unsaturated bonds
  • C09J175/16—Polyurethanes having carbon-to-carbon unsaturated bonds having terminal carbon-to-carbon unsaturated bonds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B33/00—Features common to bolt and nut
  • F16B33/004—Sealing; Insulation
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B39/00—Locking of screws, bolts or nuts
  • F16B39/22—Locking of screws, bolts or nuts in which the locking takes place during screwing down or tightening
  • F16B39/225—Locking of screws, bolts or nuts in which the locking takes place during screwing down or tightening by means of a settable material
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2190/00—Compositions for sealing or packing joints
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
  • C09K2003/1034—Materials or components characterised by specific properties
  • C09K2003/1062—UV-curable materials

Definitions

• the present disclosure relates to a material for sealing fasteners in place to, for example, prevent the ingress of water, moisture and dust, into an assembly in which the fastener is used, and a method for applying such a sealing material.
• Fasteners are used, for example, to secure components to one another.
• fasteners are used to secure components within electronic devices, such as smart phones, tablets, pads and the like.
• electronic devices such as smart phones, tablets, pads and the like.
• the components and the fasteners to secure the components getting smaller.
• the need to maintain the components free from water, moisture and dust has not changed. In fact, many such smaller devices require an even higher level of assurance that components are well isolated from the environs in order to properly function.
• sealing materials While there are known sealing materials, these materials are provided in powdered form, such as nylon 11 powder, and require that the fasteners are heated, before or after application of the material, in order for the material to melt and flow around the underside of the head of the fastener. These materials and methods of applying a sealing material work well for larger fasteners.
• sealant In other applications, such as those that use larger fasteners, the powder application of sealant to fasteners works well, but has drawbacks.
• the sealants may be subjected to elevated temperatures and may not meet certain requirements when subject to these elevated temperatures.
• fastener sealants may be required to meet certain specifications including maintaining a sealed environment of at least 85°C (185°F), maintain high adhesion to the fastener, exhibit minimal compression set, maintain the ability to withstand repeated installations and removals (tightening and loosening), maintain physical integrity (e.g., no cracking), all while maintaining a desired physical appearance.
• sealants such as those illustrated in FIGS. 9A-9E, include polymeric coatings and preformed resilient washers, such as silicone and the like. Often, such preformed washers cannot withstand the temperature requirements while
• a material that can be used to seal fasteners in an assembly and provide an acceptable seal against environmental conditions such as water, moisture, dust and the like.
• such a material is applied to the fasteners in liquid form and can readily flow around the underside of the fastener head (the bearing surface), as desired, to provide a complete covering of the underside of the head, without overspray.
• a material rapidly cures and a method of application is a non-heat or minimally heat-applying and producing process.
• such a material permits reuse of the fasteners - that is the fastener can be applied and removed and reapplied with the sealing material maintaining its sealing properties.
• Various embodiments of the present disclosure provide a fastener sealing material for application to miniature and sub-miniature fasteners.
• the sealing material is formulated from a liquid applied acrylate material, such as an acrylated urethane, and acrylated polyester and the like.
• the liquid applied material is cured using an ultraviolet or LED light source and without the use of heat.
• a viscosity of the material is less than about
• the viscosity of the material can be about 500-2000 centipoise. Such a viscosity allows the sealant to, if desired, somewhat wick up onto the shank of the fastener. This geometry may be required in certain applications. In other applications wicking is not required or desired.
• a super hydrophobic material can be included as an additive.
• additives include a suitable photoinitiator, and can include a pigment present in an amount so as to not impede curing the material, a flow modifier and a heat resistive additive material.
• the material cures on the fastener in no more than about 2-20 seconds, preferably about 2-10 seconds and more preferably about 2-5 seconds when subject to ultraviolet or LED light and at a temperature of no more than about 66 deg.C (about 151 deg.F), and preferably at about room temperature 25 deg.C (about 77 deg.F).
• Fasteners with the sealing material thereon retain their sealing characteristics following multiple installations and removals. For example, fasteners with the sealing material thereon retain their sealing characteristics following at least three installations and removals.
• the fastener sealing material when applied to a fastener, wicks on to a portion of a shank of the fastener. In other embodiments, the sealing material does not wick up on a portion of the fastener shank.
• the fastener sealing material may also, when applied to a fastener, form a locking material for the fastener. A method of making a fastener with a sealing material thereon is also desired.
• FIGS. 1 A-1H are photographs of fasteners having a known, prior art sealing material applied thereto;
• FIG. 2 is a photograph of an Ml .4 fastener bearing surface having an embodiment of the present fastener sealing material applied thereto, illustrating the flow coating of the underside of the fastener head;
• FIGS. 3A and 3B are photographs of the underside or under head
• FIGS. 4A-4B are photographs of the top side of an M 1.0 fastener before and after application of the present sealing material
• FIG. 4C is a photograph of the underside of the head and a portion of the shank of a 4-40 sized fastener following application of the present fastener sealing material;
• FIG. 5 is a photograph of a submergence test structure
• FIGS. 6A and 6B are photographs of a test chamber
• FIGS. 7A and 7B are photographs showing the ability of the material to wick up onto the shank of a fastener in which FIG. 7A illustrates a fastener prior to application of the present sealing material and FIG. 7B illustrates a fastener in which the sealing material is applied to the fastener and shows the material wicking onto a portion of the shank of the fastener;
• FIG. 8 is a photograph of a fastener with an original sealant material and blue patch (locking mechanism/material);
• FIGS. 9A-9E are illustrations of prior art sealant elements before and after use
• FIGS.10 A and 10B illustrate fasteners before (FIG. 10A) and after
• FIG. 10B application of a present sealant
• FIG. 11 illustrates an example of a taillight assembly
• FIGS. 12A-12D illustrate the pressure/vacuum testing equipment
• FIG. 13 is a graphical representation of one thermal cycling test, showing temperature (deg.C.) vs. time (hounmin);
• FIG. 14 is a graphical representation of another thermal cycling test, showing temperature (deg.C.) vs. time (hours);
• FIG. 15 shows the underside of the fastener head after 5 installations and removals of the fastener and shows no degradation (e.g., no cracking or delamination) of the sealant;
• FIG. 16 is a graphical representation of the results of seal tests that were conducted on a control groups of fasteners and a group of fasteners with a present sealant at various temperatures;
• FIG. 17 is a graphical representation of the results of cracking tests that were conducted on a control groups of fasteners and a group of fasteners with a present sealant at various temperatures
• FIG. 18 is an illustration of a fastener with the present sealant and a fastener with a known washer-type seal.
• the need to provide a seal between fasteners and components that are being fastened is paramount and is of particular importance in today’s electronic devices. This need is exaggerated by the constant reduction in size of the components within these devices.
• Known materials are not adequate for sub miniature fasteners which are fasteners having head diameters of 0.8 mm (M0.8) to 1.4 mm (Ml.4) and shank diameters of about 1 ⁇ 2 the head diameter, nor may the materials be adequate for miniature fasteners, which are those fasteners that have head diameters of about 2.0 mm (M2.0) to 3.0 mm (M3.0). And, it is anticipated that sub-miniature fasteners may in the future become even smaller.
• an embodiment of a present sealing material includes as a principal material, an acrylate such as acrylated materials, for example, acrylated polyesters, aliphatic and aromatic acrylated urethanes and the like, such as an acrylated urethane, for example, that which is available from Dymax Corporation under product names MULTI-CURE®6-621 and 6-630, and that which is available from Advanced Adhesive Systems, Inc. of Newington, CT under product numbers AAS 81082 A and 81091B.
• a super hydrophobic material additive may be added to the acrylate material, such as to an acrylated urethane to further resistance to water and moisture.
• a formulation of about 75-99 wt. percent of an acrylated urethane and about 1-24 wt. percent of the super hydrophobic material form a suitable formulation for application to miniature and sub-miniature fasteners.
• additional additives such as pigments, for example a black pigment, flow modifiers and anti-counterfeiting agents may be added in relatively small amounts to the formulation.
• a curing agent such as an appropriate photoinitiator for curing the material by, for example exposing the material applied to the fastener to UV or LED light, is present in the material.
• Flow modifiers may or may not be needed if the viscosity of the sealing material is such that it flows properly and as desired, dependent upon the fastener size, material coating thickness and wicking characteristics desired and the like.
• Heat resistant additives may also be incorporated into the formulation to prevent additional chemical and/or physical changes to the material after curing. It will be appreciated that any additives used should not be of the type to interfere with the UV or LED curing step.
• such a formulation provides a low viscosity liquid material that better lends itself to high speed application with fewer rejects.
• a low viscosity liquid material that better lends itself to high speed application with fewer rejects.
• Such a material permits high speed application onto small screws due to the low viscosity, e.g., about 500-2000 centipoise, which makes it only slightly more viscous than water.
• such materials can be cured in a relatively short period of time without the use of heat.
• the material can be cured using an ultraviolet light source (at the proper wavelength of ultraviolet light) or an LED light source, as appropriate, and based upon the type of photo initiator used. It has been found that the materials can be cured, on miniature and sub-miniature fasteners in about 2-20 seconds, and preferably in about 2-10 seconds and preferably still in about 2-5 seconds without the use of heat.
• the present material cures in about 2-20, or 2- 10 or 2-5 seconds at a temperature of less than about 66 deg.C (about 151 deg.F), and preferably at about room temperature 25 deg.C (about 77 deg.F).
• room temperature 25 deg.C (about 77 deg.F) about 77 deg.F.
• fasteners that have sealing materials such as nylon applied using heating methods that may require temperatures as high as 375 deg.F to 450+ deg.F in order to melt the nylon, may exhibit blistering of the decorative finishes on the screws.
• the present sealing material is applied as a liquid.
• the material when the material is applied to a fastener, for example, the underside of the head of a fastener (e.g., the bearing surface), the material can be formulated to readily flow around the entirety of the underside of the head, thus providing a completely wetted surface, ready for curing.
• the material can be formulated with, for example, flow additives such that it is slightly more resistant to flow and does not wick up to the bearing surface. Such a formulation may be advantageous in applications such as when the fastener threads extend fully up to the underside of the head or the bearing surface.
• the material includes no solvents, no halogens, no polyvinyl chlorides (PVCs), no REACH substances of very high concern (REACH SVHCs), no phthalates, no bisphenol A (BPA) and is RoHS (restriction of hazardous substances) compliant.
• PVCs polyvinyl chlorides
• REACH SVHCs REACH substances of very high concern
• BPA bisphenol A
• RoHS RoHS (restriction of hazardous substances) compliant.
• Adhesion performance of the sealant to the fastener can be further enhanced so that the fastener and sealant retain their characteristics following multiple installations. It has been found that enhanced performance after initial testing was exhibited when the fasteners were subjected to a plasma treatment process prior to application of the sealant to the fasteners. These plasma pre-treated fasteners exhibited a significant reduction in sealant failures after multiple installations and removals.
• Adhesion performance can also be enhanced using internal (chemical solutions) additives and treatments. Suitable treatments include treatments with adhesion promoters.
• Tests were conducted using the present sealing material on Ml .0 fasteners to determine the effectiveness of the present sealing material.
• a testing device was constructed that included a submergence test structure or tank (FIG. 5) and a submergence test chamber (FIGS. 6A and 6B) in which 10 M1.0 fasteners having the sealing material applied thereto secured a transparent plastic plate to a steel chamber.
• the sealed chamber was submerged in a column of water to a depth of 1 meter for a period of time in minutes. Four types of tests were conducted.
• the fasteners were installed and the chamber submerged for a period of 30 minutes. After the chamber was submersed for 30 minutes, the chamber was removed from the tank and examined from the bottom, through the plastic cover, to confirm that it was free of leaks. After the submergence test, the chamber was placed in an oven at about 195 deg.F (90 deg.C) for 10 minutes until the surface reached about 122 deg.F (50 deg.C). The chamber was then removed from the oven and a small amount of water was dripped on to the plastic cover. After 45 seconds, the water was wiped off of the plastic cover to confirm that the chamber was free of any signs of water vapor or droplets.
• the fasteners were installed and removed four times to show durability over multiple installations and were subsequently submergence tested.
• the chamber was submersed to a depth of about 1 meter depth for a period of 30 minutes.
• the chamber was removed from the tank and examined from the bottom, through the plastic cover, to confirm that it was free of leaks.
• the chamber was placed into an oven at about 195 deg.F (90 deg.C) for 10 minutes until the test fixture reached about 122 deg.F (50 deg.C).
• the testing device was then removed from the oven and a small amount of water was dripped on to the plastic cover. After 45 seconds, the water was wiped off of the plastic cover to confirm that the chamber was free of any signs of water vapor or droplets.
• the fasteners were tightened onto the plate and the chamber was conditioned, e.g., placed in a mechanical oven, at a temperature of about 175 deg.F (80 deg.C) for a period of 24 hours. After conditioning, the chamber was allowed to return to room temperature before the submergence test was conducted. The chamber was then submersed to a depth of about 1 meter for about 30 minutes. After submergence, the chamber was removed from the tank and examined from the bottom, through the plastic cover, to confirm that it was free of leaks.
• a temperature of about 175 deg.F (80 deg.C) 80 deg.C
• the chamber was placed into an oven at about 195 deg.F (90 deg.C) for a period of 10 minutes until the surface reached about 122 deg.F (50 deg.C).
• the chamber was then removed from the oven and a small amount of water was dripped on to the plastic over. After 45 seconds, the water was wiped off of the plastic cover to confirm that the chamber was free of any signs of water vapor or droplets.
• the fasteners were tightened onto the plate and the chamber was conditioned, e.g., placed in a mechanical oven, at a temperature of about 250 deg.F (120 deg.C) for a period of 3 hours. After conditioning, the chamber was allowed to return to room temperature before the submergence test was conducted. The chamber was then submersed to a depth of about 1 meter for about 30 minutes. After submergence, the chamber was removed from the tank and examined from the bottom, through the plastic cover, to confirm that it was free of leaks.
• the chamber was placed into an oven at about 195 deg.F (90 deg.C) for a period of 10 minutes until the surface reached about 122 deg.F (50 deg.C).
• the chamber was then removed from the oven and a small amount of water was dripped on to the plastic cover. After 45 seconds, the water was wiped off of the plastic cover to confirm that the chamber was free of any signs of water vapor or droplets.
• the fasteners were installed and removed three times at room temperature.
• the fasteners and plates were then tested at 8 psi and 16 psi for 60 seconds and inspected for leakage. No leakage was observed.
• the samples were then heated in an oven at 120 deg.C for 3 hours and then retested at 8 psi and 16 psi for 60 seconds and inspected for leakage. No leakage was observed. Adhesion of the sealant material to the fasteners was also checked, and the material could not be removed from the fasteners’ bearing surfaces.
• a similar test was conducted in which the same protocol was followed except that the fasteners were heated in an oven at 80 deg.C for a period of 12 hours rather than 3 hours at 120 deg.C.
• sealing materials can be formulated for use on larger fasteners.
• a formulation for larger fasteners may use as a principal material, an acrylate or acrylated urethane, such as that available from Dymax Corporation under product names DUAL-CURE 9481-E and 9482, or the above- referenced material by Advanced Adhesive Systems. It has been found that these acrylated urethanes have high water, chemical and heat resistance while retaining the advantageous characteristics of superior performance in sealing against water and exhibited outstanding adhesion to metals. In addition, use of these materials provides a sealing material that exhibits excellent adhesion to steel and superior durability for multiple installations with a high degree of integrity such that the sealing properties of the material-applied fasteners are retained.
• FIGS. 7 A and 7B are photographs showing the ability of an embodiment of the material to wick up onto the shank of a fastener in which FIG. 7A illustrates a fastener prior to application of the present sealing material and FIG. 7B illustrates a fastener in which the embodiment of the sealing material is applied to the fastener and shows the material wicking onto a portion of the shank of the fastener to form a cone-like shape between the shank or threads near the head of the fastener and the fastener head.
• Such wicking may be desired or required in certain applications.
• a sealing material includes as a principal material, an acrylate, such as acrylated materials, for example, acrylated polyesters, aliphatic and aromatic acrylated urethanes and the like, such as an acrylated urethane, for example, a urethane acrylated resin, which is commercially available from Advanced Adhesive Systems, Inc. of Newington, CT, under product No. AAS 82059B.
• an acrylate such as acrylated materials, for example, acrylated polyesters, aliphatic and aromatic acrylated urethanes and the like, such as an acrylated urethane, for example, a urethane acrylated resin, which is commercially available from Advanced Adhesive Systems, Inc. of Newington, CT, under product No. AAS 82059B.
• An additive such as a nanostructured chemical, such as a polyhedral oligomeric siisesquioxane (POSS) can he added to the urethane material to enhance the physical properties of the sealant.
• a nanostructured chemical such as a polyhedral oligomeric siisesquioxane (POSS)
• POSS polyhedral oligomeric siisesquioxane
• a formulation of about 90 to 97 wt. percent of an acrylated urethane and about 3 to 10 wt. percent of a nanostructured additive form a suitable formulation for application to fasteners.
• the urethane can be present at about 95 wt. percent and the nanostructured additive can be present at about 5 wt. percent of the sealant.
• additional additives such as pigments, for example a black pigment, flow modifiers and anti-counterfeiting agents may be added in relatively small amounts to the formulation.
• a curing agent such as an appropriate photoinitiator for curing the material by, for example exposing the material applied to the fastener to UV or LED light, is present in the material.
• Flow modifiers may or may not be needed if the viscosity of the sealing material is such that it flows properly and as desired, dependent upon the fastener size, material coating thickness and wicking characteristics desired and the like. It will be appreciated that any additives used should not be of the type to interfere with the UV or LED curing step.
• such a formulation provides a low viscosity liquid material that better lends itself to high speed application with fewer rejects.
• a material permits high speed application onto fasteners due to the low viscosity, e.g., about 500 to about 2000 centipoise (cP), and about 1300 cP, which makes it only slightly more viscous than water.
• such materials can be cured in a relatively short period of time without the use of heat.
• the material can be cured using an ultraviolet light source (at the proper wavelength of ultraviolet light) or an LED light source, as appropriate, and based upon the type of photo initiator used. It has been found that the materials can be cured, on fasteners in about 2-20 seconds, and preferably in about 2-10 seconds and preferably still in about 2-5 seconds without the use of heat.
• the present material cures in about 2-20, or 2-10 or 2-5 seconds at a temperature of less than about 66 deg.C (about 151 deg.F), and preferably at about room temperature 25 deg.C (about 77 deg.F).
• room temperature 25 deg.C (about 77 deg.F) can be carried out without the need for induction or other types of heating.
• the present liquid-applied sealing material because of its low viscosity, when applied to a fastener, for example, the underside of the head of a fastener (e.g., the bearing surface), can be formulated to readily flow around the entirety of the underside of the head, and to wick along a portion of the thread or shank adjacent to the head forming a cone-like shape, thus providing a completely wetted surface, ready for curing.
• the material can be formulated with, for example, flow additives such that it is slightly more resistant to flow and does not wick up to the bearing surface.
• FIG. 10A shows the fastener prior to application of the sealant and FIG.
• FIG. 10 B shows the fastener with the sealant applied and wicking along the upper-most threads to form the cone-like shape.
• Such a formulation may be advantageous in applications such as when the fastener threads extend fully up to the underside of the head or the bearing surface.
• a fastener having the sealant applied to it and following installation and removal 5 times, is shown in FIG. 15. It can be seen that no cracking or delamination of the sealant has occurred.
• the material includes no solvents, no halogens, no polyvinyl chlorides (PVCs), no REACH substances of very high concern (REACH SVHCs), no phthalates, no bisphenol A (BPA) and is RoHS (restriction of hazardous substances) compliant.
• the sealant is free of sulfur-containing compounds, plasticizers and out-gassing materials.
• fasteners having the present sealing material exhibit superior performance in sealing against water and that the cured material has outstanding adhesion to metals. It has also been found that fasteners having the present sealing material exhibit excellent adhesion to steel and superior durability for multiple installations; that is the fasteners can be installed and removed multiple times and the material remains in place, with a high degree of integrity, such that the sealing properties of the material-applied fasteners are retained. It was also observed that the present sealing material exhibited good water resistance and high temperature, e.g., heat resistance, up to at least about 85 deg.C (185deg.F).
• Tests were conducted to determine the effectiveness of a sealant having a nanostructured chemical, such as a polyhedral oligomeric silsesquioxane (PQSS) additive.
• the sealant was formulated with about 95 wt. percent of an acrylated urethane and about 5 wt. percent of a nanostructured additive.
• the first set of samples had a polyurethane coating only (a base or control) and the second set of samples had a polyurethane (at 95 wt. %) and nanostructured chemical (PU/POSS) (at 5 wt. %) sealant applied thereto.
• PU/POSS nanostructured chemical
• FIG. 11 illustrates an automobile taillight assembly and the fasteners F1-F3 that are used to secure the parts of the two-part assembly in a sealed condition. It is contemplated that the present sealant will be used on the fasteners for sealing the assembly.
• Fasteners with the sealant were tested in an environment to simulate fastening the taillight assembly portions (to fasten the two portions of the taillight assembly to one another in a two-article system). The simulated environment was established using the pressure/vacuum testing equipment illustrated in FIGS. 12A- 12D.
• the fasteners were coated with the sealant described above and were cured using UV light for a period of 25 seconds. The UV light used had a relatively low intensity and it is contemplated that a UV light source of a higher intensity will be used in production.
• a testing device was constructed that included a submergence test structure or tank and a submergence test chamber (FIGS. 12A-12D) in which 5 M3.0 fasteners having the sealing material applied thereto secured a steel plate to a steel chamber (a two article system).
• the tested were conducted in accordance General Motors Worldwide procedure GMW14906 4.5.4.3, Pressurization Seal Test.
• the sealed chamber was submerged in water in the submergence tank to a depth of 1 inch (2.5cm).
• the interior of the chamber was pressurized to a pressure of 1 psig (7kPa) for a period of 5 minutes.
• the samples were tested both before and after thermal cycling.
• the samples were first heated to a temperature of 176 deg.F. (80 deg.C.) +/-5.4 deg.F. (+/-3 deg.C.) for a period of 48 hours, and then returned to ambient temperature 73 deg.F. (23 deg.C.) +1-9 deg.F. (+/-5 deg.C.) for a period of greater than 15 minutes, and then cooled to a temperature of -40 deg.F. (-40 deg.C.) +/-5.4 deg.F. (+/-3 deg.C.) for a period of 24 hours.
• the samples were then allowed to return to ambient temperature 73 deg.F. (23 deg.C.) +1-9 deg.F. (+/-5 deg.C.) for a period of greater than 15 minutes and pressure and vacuum tested. All of the samples passed pressure and vacuum tests.
• a subsequent test was conducted to test to failure under pressure in accordance General Motors Worldwide procedure GMW14906 4.0.2.8.8.3.
• the pressure in the device was increased to 0.25 psig (1.75kPa) for 1 minute after which the pressure in the device was increased by .25 psig (1.72kPa) increments below 1.52 psig (10.5kPa) and .5 psi (3.5kPa) increments above 1.52 psig (10.5kPa) and held for a period of 1 min. at each increment to reach failure.
• the pressure was increased to 10 psig (68.9kPa) after which the test was terminated due to safety concerns.
• the 10 psig pressure was ten times the required pressure. None of the samples failed prior to test termination.
• thermal cycling temperatures vs. time is shown in FIG. 13. The samples were then tested and all of the samples passed the pressure and vacuum tests.
• FCA PF.90078 5.2.1 Sealing Requirement Submergence Test.
• FCA PF.90078 5.2.1 Sealing Requirement Submergence Test.
• a sealed chamber was submerged in water in the submergence tank and the interior of the chamber was pressurized to a pressure of .75 psig (5.2kPa) for a period of 60 seconds at room temperature. All of the samples passed with no leakage.
• the sealant is harder than known sealant materials, having a hardness of about 55-60 Shore D, compared to known sealants that have a hardness of about 30-70 Shore A.
• a 55-60 Shore D hardness is about equivalent to a 100 Shore A hardness.
• Enhanced hardness provides better toughness and tear resistance.
• the sealant exhibited no signs of cracking or delamination following the above noted GMW and FCA testing.
• fasteners with the sealant were exposed to a variety of chemicals commonly found in vehicles and the automotive industry, including, 50 percent methanol in water, antifreeze and coolants, wheel cleaners, automatic transmission fluid, car shampoo, automobile glass cleaners, paintwork cleaning products, oil cleaner, bug and tar remover, diesel fuel, ice spray wax and motor oil.
• the fasteners with the sealant were subject to these chemicals for a period of 24 hours, after which they were visual inspected and exhibited no signs of degradation, delamination or cracking.
• the sealant as applied to fasteners tends to wick along the shank or upper threads of the fastener and under the head of the fastener, forming a cone-like shape. As such when tightened against a mating part/surface, the seal occurs along a circumferential line, rather than across the entirety of the mating parts, which concentrates the force exerted by the mating threads. This is in contrast to flat resilient washers (e.g., that function as gaskets) which compress along the entirety of the parts, resulting in greater force or softer material needed to compress the material and form the seal.
• flat resilient washers e.g., that function as gaskets
• the present material is not prone to tearing and provides a better sealing geometry (e.g., sealing against a cone, rather than against the flat of a cylinder). There is also a shorter leak path (see, for example, FIG. 18) compared to flat washers in that the present sealant adheres to the fastener and wicks onto the shank and threads near the underside of the fastener head, whereas the flat washer is loosely fitted on to the fastener and as such has leak paths as indicated at L.
• the present sealing material serves multiple functions. As such, in addition to its use as a sealing material, it can also function to lock a fastener in place, without the need for secondary processing to, for example, apply a locking patch (e.g., a nylon 11 patch), thereby resulting in additional productivity improvements and reducing the complexity and steps required in manufacturing.
• the sealant may be applied to the threads to serve as a thread locking material, with or without use as an under-head sealant.
• a method of making a fastener with a sealing material thereon includes the steps of applying a liquid applied acrylate material to the fastener and curing the liquid applied acrylate material using an ultraviolet or LED light source and without the use of heat.
• the method can include pretreating the fastener with a plasma treatment.
• the liquid applied acrylate material can be any of the above-described materials, including a suitable photoinitiator, a nanostructured material, such as a polyhedral oligomeric silsesquioxane (POSS), other additives such as a pigment present in an amount so as to not impede curing the material, a flow modifier and a heat resistive additive material.
• a super hydrophobic material may also be included as an additive.

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• 2019
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