WO2001005882A1

WO2001005882A1 - Lubricious sealant compositions

Info

Publication number: WO2001005882A1
Application number: PCT/US2000/018555
Authority: WO
Inventors: Frederick F. Newberth, Iii; Paul J. Rachielles; John P. Breault; Thomas Fay-Oy-Lim; Peter J. Chupas; Richard O. Angus, Jr.
Original assignee: Loctite Corporation
Priority date: 1999-07-15
Filing date: 2000-07-05
Publication date: 2001-01-25
Also published as: AU6075300A

Abstract

The present invention provides a lubricious sealant composition that may be applied to a host article, allowed to dry and subsequently cured by heat or other mechanisms. The sealant composition includes a curable component which desirably is heat curable, and a lubricious agent uniformly incorporated therein. The lubricious sealant compositions facilitate the fitting together of mated parts and is subsequently cured, creating an excellent adhesive bond between the mated parts.

Description

LUBRICIOUS SEALANT COMPOSITIONS

FIELD OF THE INVENTION

The present invention relates to lubricious sealant compositions that are applied to a host article, allowed to dry and subsequently cured. In particular, the inventive compositions are applied to an article, such as a hose commonly used in the assembly of engines in the automotive industry, allowed to dry in an uncured state, fitted into place on a housing and cured. Curing may be accomplished using various mechanisms, either under a separate step or under normal activity and use of the hose.

BRIEF DESCRIPTION OF RELATED TECHNOLOGY

Sealants are often used in the automotive industry between matable parts, such as a housing and a hose. Sealing in such applications is necessary for the proper functioning of the automotive engine.

Non-curable sealants for hose/housing connections often involve merely a "soapy water" lubricant, which of course provides no sealing over time beyond that which is provided initially at the hose/housing interface.

Curable sealants may be generally applied to a portion of an article to be mated, allowed to cure and then assembled on the mated part. Once the sealant is cured, however, the surface lacks lubricity. For example, the cured surface of sealants, whose constituents are silicones, urethane-acrylates and the like, do not naturally exhibit lubricitity. In many applications, this resultant lack of lubricity at the surface makes it difficult to fπctionally engage other parts, since the clearance between mated parts, such as a housing and a hose, are designed to provide a very tight fit to prevent leaks In both manual and machine assembly processes, frictional movement of the matable parts against the cured sealant occurs, may cause debraiding of the sealant or mated parts and provide leak pathways. In such cases, cleaning of the parts and reapplication of the sealant may be required In addition, from an ergonomic standpoint the frictional forces from placing a hose on a housing often cause repetitive stress-type injuries to workers

Advances in sealant technology have led to the incorporation of lubricity additives into sealants to alleviate some of the inherent non-lubricious nature of the final cured sealant, lowering the frictional forces on the hoses and sealant These lubricious sealants may be able to facilitate repeated assembly and disassembly with a lower incidence of defects in the seal. However, these lubricious sealants still rely on a tight interference fit for sealing as opposed to the adhesion to both mating parts Applications which rely largely on frictional forces for sealing create greater opportunities for the formation of stress cracks and, therefore, require greater care in both the tolerances of the parts as well as assembly thereof. In certain applications, such as the joining of automotive engine hoses to their housings, manual assembly is necessary to ensure the quality of the fit Yet, the coupling of automotive engine hoses with their housings results in repetitive stress injuries to the workers. Such injuries are costly to both the workers, their employers and the manufacturing process, generally

Thus, there is a need for a sealant composition which can be applied and dried on a surface, without curing, frictionally engaged with another part with ease and subsequently cured to form a seal.

SUMMARY OF THE INVENTION

The present invention alleviates the above-mentioned drawbacks of conventional sealant compositions. In particular, the present invention provides curable sealant compositions, which may advantageously be applied to one or more frictionally mating parts, dried to form a lubricous but adherent surface, and subsequently may be cured to enhance the seal therebetween One particularly desirable application is to coat the interior diameter of a hose and fitted onto its mated part housing and thereafter cured The lubricious sealant composition desirably incorporates a curable component which forms an elastomeric or flexible plastic material upon cure

In one aspect of the present invention, there is provided a lubricious sealant composition which includes a curable elastomeric or flexible plastic resin and a lubricious agent incorporated therein The lubricious agent is desirably suspended or dissolved therein and is available to impart lubricity to the cured surface of the resin The lubricious agent may self-migrate to the surface of the cured composition to provide ongoing lubricity during use. A number of elastomeric and flexible plastic resins are useful in the present invention, including silicone resins, polyurethane resins, latex resins, acrylic resins, polybutadiene resins, ethylenepropylene diamine resins, polyisoprene rubbers, styrene-butadiene rubbers, polydisulfide rubbers, and the like

In yet another aspect of the present invention, there is provided a cured lubricious sealant composition which has a lubricious surface imparted thereto by virtue of a lubricious agent being embedded therein The lubricious agent is most desirably available to the surface to lower frictional forces when the cured surface is in frictional engagement with another surface The lubricious agent lowers the coefficient of friction of the surface of the resultant article

In still another aspect of the present invention, there is provided a method of imparting surfacing lubricity to an elastomeric or flexible plastic material which includes providing a curable elastomeric or flexible plastic resin and embedding a lubricious agent within said resin such that the lubricious agent imparts lubricity to a cured surface of said resin

In another aspect of the present invention, there is provided a lubricious sealant composition having a heat curable component, a lubricious agent and an initiator The composition desirably dries to a lubricious adherent film prior to cure, thereby providing ease of engagement with mating parts prior to formation of the final seal

The lubricious agent employed in the present invention may be selected from polyethylene, polytetrafluoroethylene, talc, graphite, boron nitride, perfluoropolyethers, tetraoximino silanes, and the like, waxy materials such as polyethylene and polypropylene waxes, and liquid materials such as polybutene, hydrogenated polybutene, polydimethylsiloxane, and the like

The lubricious agents may be inert or unreactive particles which serve to provide lubricity to an otherwise substantially non-lubricious surface The lubricious agents may alternatively be reactive with each other or other components of the composition Regardless of the type of lubricious agent, a sufficient amount of lubricious agent is incorporated into the sealant composition to impart surface lubricity and lower the coefficient of friction of the curable resin component per se In certain embodiments of the invention, it is desirable to choose a lubricious agent which naturally blooms or migrates to the surface of the cured composition This provides for initial and ongoing lubricity and lowering of the coefficient of friction

In another aspect of the present invention, there is provided a method of imparting surface lubricity to an article that includes providing a lubricious sealant composition to the surface of the article The sealant composition includes a heat curable component, lubricious agent within the heat curable component and an initiator

In another aspect of the present invention, there is provided an article having a resin component and a lubricious sealant composition therein

In yet another aspect of the present invention, there is provided an article with a coating composed of the inventive sealant composition BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1 and 2 are graphs of frictional force measurements taken on various inventive and control compositions during the assembly of a rubber hose and a metal hose housing for an automobile.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to lubricious sealant compositions that have a lubricious agent capable of lowering the coefficient of friction of the surface on which it is to be applied. The inventive compositions have excellent lubricious and sealing properties not found in conventional sealants. The uncured preapplied inventive composition advantageously maintains its full lubricious nature when the matable parts are joined. This enables articles coated with the inventive compositions to be installed with greater ease than articles coated with conventional lubricious and non-lubricious sealants.

After the matable parts are fitted together, the inventive sealant compositions cure upon the application of an appropriate amount of heat. As the inventive sealant composition cures the matable parts are bonded, creating a lasting seal. Thus, the lubricious nature facilitates the fitting together of mated parts and the subsequent curing of the composition, thereby creating excellent adhesion between the mated parts.

The sealant compositions of the present invention are desirably applied to a hose, such as those used in the automotive industry, prior to fitting the hose to a hose housing with which it is to be mated. Although the "preapplied" hose sealant composition may be cured prior to its application, it is desirably not cured prior to use of the hose. The inventive sealant composition is desirably applied at a certain distance on the interior diameter of the hose and dried by air or mild heat that will not effect the curing of the composition. The inventive compositions advantageously maintain their full lubricious nature as the matable parts are fitted together. Thus, an article to be formed from mated parts and sealed with the inventive composition may be more easily assembled despite a tight fit between the mated parts. The inventive compositions are extremely stable, have a long shelf-life and have the further advantage of not requiring a separate curing step prior to shipping.

After the matable parts are fitted together, the inventive sealant compositions are desirably cured upon the application of an appropriate amount of heat. The inventive sealant compositions are particularly useful in the automotive industry where the inventive sealant composition can be heat cured after fitting a hose onto a housing by the heat emitted from an engine during its normal activity and use. As the inventive lubricious sealant composition cures, the matable parts are bonded, creating a lasting seal. Once cured, the inventive sealant composition has enhanced sealing and adhesive properties between the mated parts.

In a particularly desirable aspect of the invention, the inventive sealant composition contains a heat curable component, a lubricious agent, and an initiator, such as an azo compound or a peroxyketal. Coating the inventive composition onto an article provides ease of assembly and lasting sealability after curing.

For purposes of this invention, the term "lubricious agent" refers to any material added to a curable composition which imparts lubricity thereby lowering the coefficient of friction on the surface of the cured composition. The term "lubricity" refers to a lower coefficient of friction, such as those values obtained with the inventive compositions, as compared to the composition without the lubricious agent.

The lubricious agent may be selected from a wide variety of materials. When mixed with the heat curable component, the lubricious agent is desirably a particulate which can remain uniformly suspended in the composition or is a wax or liquid material, which can be uniformly mixed into or dissolved in the resin to impart lubricity to the surface of the composition or article once dried and cured. Among the lubricious agents suitable for use herein, include, without limitation, solid particulates of polyethylene, polytetrafluoroethylene, talc, graphite, perfluoropolyethers, molybdenum disulfide, tungsten disulfide, calcium fluoride, graphite fluoride, polytetrafluorethylene fluorotelemers, and the like. Combinations of lubricious agents are also desirable. Boron nitride is one of the more desirable lubricious agents useful in the present invention.

Among the useful waxy lubricious agents are polyethylene waxes and polypropylene waxes. Desirably, these waxes have a melting point range of 150°C-250°C, but waxes having melting point ranges outside of this may be useful depending on the intended application. Useful liquid lubricious agents include polybutene, hydrogenated polybutene, and the like. These liquid lubricious agents desirably have an average molecular weight range of up to about 15,000, and a viscosity of about 4,000 to about 10,000 cPs.

The compositions of the present invention may incorporate the lubricious agent in various ways. The lubricating agent may be soluble or miscible with the heat curable component or it may be present as a suspension or emulsion in the heat curable component. In one aspect of the invention, the lubricating agent is desirably incompatible with the heat curable component within which it is suspended. The term "incompatible", as used herein, refers to a substance which is not miscible with nor able to form a solution within its host, i.e., it will not dissolve when combined with the base composition. Accordingly, the lubricious agent should ordinarily be suspended in particulate form within the composition. The term "particulate form" as used herein refers to the lubricious agent in distinct, separate components dispersed throughout the composition in such a way that the lubricious agent is in a non-continuous phase within the composition. In one aspect of the invention, the lubricous agent particles are suspended in the composition and, when the latter is cured, become "locked" in place.

The lubricious agents may be inert or unreactive particles which serve to provide lubricity to an otherwise substantially non-lubricious resin surface. Alternatively, the lubricious agents may be reactive with other components of the composition. Regardless of the type of lubricious agent, a sufficient amount of lubricious agent is incorporated into the composition such that the lubricious agent is desirably made available to the surface of the coated article, in order to impart surface lubricity and lower the coefficient of friction of the article. In certain embodiments of the invention, it may be desirable to choose a lubricious agent which naturally blooms or migrates to the surface. This provides for initial and ongoing lubricity and lowering of the coefficient of friction.

The lubricious agent is suspended or otherwise incorporated within the composition in amounts sufficient to lower the coefficient of friction on the surface of the composition. These amounts range from about 0.1% to about 60% by weight of the total composition and desirably in amounts of about 5% to about 35% by weight of the total composition.

The lubricious agents can be selected such that they do not leave a film residue on the other surfaces in which they come in contact with. For example, if the cured compositions of the present invention are placed in frictional contact with a substrate, desirably no residue of the lubricous agent is left on the substrate.

When the lubricious agent is present in particulate form, the particle size will vary greatly depending on the type of lubricant. Generally, particle sizes of up to about 300 microns may be employed.

Boron nitride, one highly desirable lubricious agent in the present invention, is a synthetic ceramic material, which offers high heat capacity and outstanding thermal conductivity, as well as lubricity. It is an inert, white material having a hexagonal, plate-like crystal structure resembling that of graphite. It is non-abrasive and unctuous to the touch. It is most commonly used in powder form. Particle size ranges of about 5 to about 44 microns are desirable.

Various fluoropolymers such as polytetrafluorethylene (PTFE), often commonly refeπed to as Teflon®, are also suitable for use as the lubricious agent. PTFE is a white granular fluoropolymer powder which is both chemically inert, and capable of imparting lubricious properties to the elastomeric compositions of the present invention. PTFE is often mixed with inorganic fillers to selectively enhance its properties Combinations of PTFE and other polymers such as polyethylene particulates are also contemplated as lubricious agents

Additionally, fluoroadditive powders such as Zonyl^® are useful as the lubricious component in the present invention Zonyl^® is a registered trademark of the Dupont Company. It is a small particle powder especially suitable for improving the lubriciousness of coatings. It has an average agglomerate size of 1 8 to 4 μm

Various perfluoropolyether compounds are also suitable for use as the lubricious agent in the present invention For example, oils and waxy particles having the general formula F[CF(CF3)CF₂0]_nCF₂CF₃, and sold under the trademark Krytox®, are among those useful These materials are non-flammable and extremely stable lubricants with a host of high- performance applications These materials are available in a variety of molecular weights which dictate their physical state as an oil or waxy material These materials are desirable because they are chemically inert, nonflammable, thermally stable, and offer outstanding lubricity

The heat curable component of the present invention desirably cures when subjected to the heat emitted by the engine of the automobile Thus, the heat curable component will desirably cure at a temperature that is less than the normal operating temperature of an engine of an automobile and greater than room temperature The heat curable components are generally employed in amounts of about 40% to about 95% by weight of the total composition Desirably, they are used in amounts of about 55% to about 90% by weight.

A variety of silicone compositions can be employed in the present invention Silicone rubber and liquid compositions exist in various forms as characterized by their differing cure chemistry, viscosity, polymer type, and purity They can be formulated into one-part or two- part systems and a particular silicone composition can be engineered to be cured by more than one mechanism. Moisture-curing mechanisms, heat-curing mechanisms, and photo initiating mechanisms are among the means used to initiate cure, i e , cross-linking of reactive silicones. These mechanisms are based on either condensation reactions, whereby moisture hydrolyzes certain groups on the silicone backbone, or addition reactions which can be initiated by a form of energy, such as electromagnetic radiation or heat. For example, reactive polyorganosiloxanes can be cured by heat in the presence of a peroxide. Alternatively, these reactive compounds can also be cured by heat in the presence of silicone hydride-containing (- SiH) compound and a metallic hydrosilation catalyst, such as an organo-platinum catalyst.

The most desired elastomeric silicone resins for use in the present invention include oxime-curable silanol compositions. The silicone resins may be heat-curable, room temperature curable, UV curable, moisture curable, or capable of curing by more than one of these mechanisms.

Latex resins, i.e. water-based emulsions or dispersions, are useful as the heat curable component of the present invention and include aqueous acrylic emulsions, such as those commercially available from Union Carbide under the trade name UCAR®. Polyurethane resins useful in the present invention include urethane-acrylate emulsions, such as aliphatic urethane-acrylate emulsions. These polyurethane resins may be combined with a reactive diluent monomer and an initiator.

In the case where the heat curable component is to be cured prior to assembly with a mating part, a lubricious surface is still obtainable due to the incorporation of the lubricious agent. Other useful heat curable components which may be used alone or in conjunction with latex materials may be selected from a wide variety of materials which when cured will benefit from the presence of the lubricious agent. The more desirable heat curable components include elastomeric and flexible plastic resins, such as silicone resins, polyurethane resins, latex resins, polyester resins, acrylic resins, polybutadiene resins, ethylene-propylene-diamine monomers (EPDM), polyisoprene rubber resins, polysulfide rubber resins, and styrene- butadiene copolymers, polydisulfide rubbers and the like. These resins generally do not exhibit a lubricious surface when dried or cured. Like most rubbery materials, these resins tend to create slip-resistant surfaces rather than lubricious ones. The initiator used in the inventive composition acts to cure or catalyze the cure of the composition. Desirably the initiator is a metal insensitive initiator. Useful initiators include amines, peroxides, and the like and are generally incorporated in amounts of about 0.1% to about 0%) by weight of the total composition. Useful peroxy compounds include the peroxides (organic as well as inorganic), hydro peroxides and peresters, including, for example, cumene hydroperoxide, t-butyl hydroperoxide, methyl ethyl ketone hydroperoxide, t- butyl perbenzoate and benzoyl peroxide. Other initiators which may be employed include peroxyketals and azo initiators, such as those available from DuPont under the Vazo trademark, azo-bis-isobutyronitrile, N-methyl diethanol-amine benzophenone, chlorothioxanthone, diethoxyxanthone, benzoin isopropyl ether, benzoin methyl ether, benzophenone and diethoxy acetophenone. Particularly useful initiators include 2,2'-azobis[2- methyl-N-(2-hydroxy)propionamide],azobis-2-methylbutyro nitrile and combinations thereof.

Desirably, the sealant composition is applied to an article and air dried or dried by applying mild heat, which is desirably insufficient to effect the curing of the composition. The article with the dried sealant composition thereon or therein can be shipped in this state. The article coated with the inventive sealant adhesive composition has good stability and shelf-life. The coated article is used by fitting the article, such as an automotive hose, onto the mated housing. The inventive lubricious sealant provides lubrication to the fitted parts and allows the coated hose to be easily fitted onto the housing. Articles having the inventive lubricious sealant thereon or therein can be assembled with other component parts without debraiding that may be caused by the frictional forces of assembly that may otherwise compromise the seal. Once the hose is in position, heat may be applied to the article to cure the inventive composition. Desirably, heat emitted through normal operation by the engine of the automobile will effect the curing of the sealant.

Alternatively, the inventive composition can be applied to the housing of the mated part instead of on the hose. It is possible to use the inventive lubricious sealant compositions on metal couplings such as aluminum housings for rubber hoses. The compositions of the present invention may also be applied to or incorporated in numerous other substrates such as gaskets, o-ring seals, press-fit seals, or other similar fitted seals

The sealant compositions of the present invention may include suitable additives such as curing agents, catalysts, viscosity modifiers, dispersing agents, surfactants, anti-foamers, diluents, pigments, thickeners, adhesion promoters, and combinations thereof Useful additives include polypropylene glycol based defoamer, polysiloxane in polyglycol, polyether modified polydimethylsiloxane, N, N-dimethylacrylamide, dibutylphthalate, ethoxylated trimethylol propane triacrylate, and combinations thereof The specific additive will depend largely on the type of curable component chosen

The present invention also provides an article having a curable resin component and a lubricious sealant composition therein The resin component may be curable by any means such as moisture curing, heat curing and photo initiating mechanisms In this embodiment a dual or multi-curing mechanism is contemplated

The following examples serve to illustrate the invention, without in any way restricting its spirit and scope All percentages throughout the specification and claims are by weight of the total composition unless otherwise indicated

EXAMPLES

The following inventive compositions as set forth in Table 1 below were prepared. Each of the compositions were prepared in a similar manner The silicone resin compositions were first prepared as follows Silanol and silica were combined with aluminum pigment and calcium carbonate fillers, mixed and heated until the fillers were properly wetted The resulting combination was then heated in a vacuum at approximately 100°C and mixed for an additional two hours

After cooling, crosslinking agents are added, and the solution is then mixed again in its entirety The solution is then cooled below 50°C, and the lubricious agent is added under a nitrogen blanket Compositions 1-15 are similar silicone compositions with various amounts and types of lubricious agents. Compositions 1 and 13 are control samples and do not contain a lubricious agent. Compositions 2-12, 14-16 represent lubricious compositions of the present invention.

TABLE 1

-.

Hydroxy terminated polydimethylsiloxane (5 ,000-7,000 cps)

² Carborundum brand Boron Nitπde Powders having U S mesh screen sizes indicated by -325 (44 microns) and -605

³ Aminopropyltrimethoxysilane

Table 2 shows the results of average peak load upon assembly of aluminum hose housings using the compositions from Table 1 The compositions of Table 1 were cured in situ on the external diameter of the housing of a metal hose coupling, followed by assembly of a rubber hose onto the portion of the housing coated with the inventive compositions Insertional forces represented by peak load (lbs) was calculated by an Instron testing machine The surface area and thickness of the cured compositions were substantially the same for each of the tests The insertional force was measured as the hoses were fitted onto the aluminum housings The amount of work, i e , force exerted over a given distance, was subsequently calculated by plotting load force versus displacement in inches The area under each curve represented the work done The average work peak load (lbs ) and work done is shown in Table 2 The averages were obtained from seven test runs Sample tests were run with no lubricious agent or sealant composition, as is the standard industry practice A control composition 1 was run using a sealant composition substantially the same as the inventive lubricious sealant compositions, except without the lubricious agent As indicated in Table 2, the insertion force (average peak load) required to assemble was highest for the control sample Compositions 2-12 and 14-16, representative of the inventive compositions, generally required less force to assemble, indicating a lower coefficient of friction as compared to the control

TABLE 2

*Hose housing assembled without lubricious sealant composition.

** Hose housing assembled using sealant composition without lubricious agent.

Table 3 shows Compositions 17-22 representative of the inventive lubricious compositions These compositions are aqueous acrylic latex emulsions containing various lubricious agents as shown The compositions were applied to the internal diameter of a hosing and cured The hosing was then fitted onto a metal housing and the "push-on" force required to couple the mating parts was measured on an Instron test machine As indicated in Figure 2, the assembly forces were generally significantly lower with the inventive compositions as compared to the control, which was the acrylic latex composition UCAR 123 without a lubricious agent incorporated therein Lower assembly forces are indicative of a reduction in the coefficient of friction of the cured resin composition

TABLE 3

Boron Nitπde mesh sιze-325 Figure 1 shows the results of testing performed on Compositions 10-16 Sample compositions 10-15 were applied to the external diameter of metal hose housings and cured The cured compositions represented approximately the same thickness and surface area for each test The housings were then coupled with a rubber hose by inserting the hose over the portion of the housing coated with the inventive compositions The frictional force to assemble the parts was then measured using an Instron machine The results, shown in Figure 1, generally indicate a reduction in the coefficient of friction of the inventive formulations

Composition 16 was applied to the internal diameter of the rubber hose, as opposed to the external diameter of the metal hose housing This composition demonstrated the greatest reduction in frictional forces The sample labeled "NS" in Figure 1 , represents the force required to assemble the hose and housing without any sealant composition present

Compositions 23-24

Various additional compositions were prepared and tested for their suitability as the inventive lubricious adhesive sealant compositions Compositions, as shown in Tables 4, 5 and 7, were prepared by combining the respective components and uniformly mixing them together

Subsequently, the compositions were tested for their ability to act as lubricious adhesive sealant compositions Tests performed included a lap shear test and lubricity tests

Compositions 23-24, as shown in Table 4, were prepared according to procedure previously described and include an aqueous acrylic latex emulsion as the curable resin component, boron nitride as the lubricious agents and azobis-2-methylbutyro nitrile as the metal sensitive initiator A control composition, as shown in Table 4, that did not contain a lubricious agent was also prepared The compositions in Table 4 were tested for lap shear strength by applying the composition to an EPDM substrate and allowed to air dry An aluminum substrate was clamped to the coated EPDM substrate and heat cured at 280°F for one hour Lap shear strength was tested using an Instron tensometer The lap shear substrate sample coated with composition 23 had better shear strength than lap shear substrate sample coated with composition 24 and did not break as easily. The control composition, which did not include a lubricious agent, had excellent lap shear strength, yet had poor lubricity. From the compositions of Table 4, it was determined that compositions with a lower lubricious agent concentration, had better adhesive properties.

TABLE 4

^* UCAR 625® is a registered trademark of Union Carbide for an acrylic latex emulsion.

Compositions 25-42

The lap shear strength and lubricity properties of additional compositions, as set forth in Tables 5 and 7, were evaluated. Each composition was prepared in a similar manner by mixing the components vigorously together to form a homogenous mixture. The urethane-acrylate emulsion used for preparing the compositions of Table 6 and 7 is manufactured by Zeneca and sold under the trade name of NR-3709.

Lap shear tests were performed to evaluate the adhesive strength of the cured sealant composition. Test specimens, in which compositions in Table 5 and 7 were applied thereto, were prepared by assembling a one-half square inch EPDM substrate coated with air dried sealant composition onto a one-inch wide Alclad aluminum shear substrate The backside of the EPDM substrate was supported with a rigid aluminum plate and the assembly was clamped together with stationary-type binder clips The assembly was cured in a convection oven at 82°C for three days, cooled to room temperature and the clips and backer plates were removed The shear adhesion strength between the two substrates was measured using an Instron tensometer and recorded, as shown in Tables 5 and 7

The lubricious nature of the lubricious adhesive sealant composition was tested by evaluating the ease of assembly of two mated parts An Instron tensometer was used to measure the maximum force required to push a coated hose onto a housing and the total amount of energy required to push a coated hose into the housing The test samples were prepared by applying the compositions in Tables 5 and 7 to an industry standard distance inside an EPDM automotive cooling system hose A thin film of the composition was applied to the hose by hand or a brush. The coated tubes were allowed to air dry for about 12 hours The coated surfaces felt more slippery than the surface of the uncoated hoses The compositions had approximately the same thickness and surface area for each test The housings were then coupled with a rubber hose by inserting the hose over the portion of a housing coated with the inventive compositions The maximum push-on force and total push-on energy measured are considered to be indicative of the lubricious nature of the composition and how well the composition will facilitate the fitting of a hose over a hose housing A lower push-on force and push-on energy indicates a lower coefficient of friction and suggests that the mated parts will be more easily assembled and therefore reduce the risk of leakage passageways

Compositions 25-42, as shown in Table 2, include an urethane-acrylate emulsion as the curable resin component, 2,2-Azobis [2-methyl-N-(2-hydroxy) propionamide] as the metal insensitive initiator, boron nitride as the lubricious agent and the following additives, polypropyl glycol based defoamer and diethylene glycol monobutyl ether The urethane-acrylate emulsion was used for preparing the compositions of Table 5 and 6 Varying amounts of the components, as shown in Table 2, were used to test the effect, if any, they had on the lubricious and adhesive properties of the composition Amounts of the additives had a negligible effect on the physical properties of the composition As shown in Table 5, higher amounts of the lubricious agent did not greatly reduce the maximum push-on force or total energy used in pushing the hose on the housing However, higher amounts of the lubricous agent decreased the lap shear strength of the composition Thus, it was determined that higher load amounts of the lubricous agent undesirably decreased the adhesive properties of the composition The other non-lubricious components were determined to not affect the physical properties of the composition Based on these results, the base emulsion, as shown in Table 6, was prepared to further test the effect of the lubricous agent on the physical properties of the composition

TABLE 5 SEALANT COMPOSITIONS

- -

TABLE 6 Composition of Base Emulsion

Compositions 43-58

As shown in Table 7, compositions 43-58 were prepared by mixing the base emulsion, as shown in Table 7, with two different lubricous agents. The resulting compositions were tested for their lubricious and adhesive properties. Compositions 43 and 44 were control compositions and did not contain any lubricous agent. Compositions 43 and 44 made it evident that compositions without a lubricous agent required a higher maximum push-on force and total push- on energy, however, had excellent lap shear strength. Compositions containing high loads of a lubricous agent tended to have a lower maximum push-on force and total push-on energy values but a reduced lap shear strength. As the lubricous agent load was further increased, the push-on force and energy was not significantly reduced, however, the lap shear strength of the compositions were significantly and undesirably reduced. Low to moderate loads (3-35% by weight) of the lubricous agent were found to be particularly desirable. Combinations of Zonyl® and boron nitride in the same composition did not noticeably enhance the physical properties of the inventive compositions. TABLE 7

PHYSICAL PROPERTIES OF INVENTIVE COMPOSITIONS

¹ Components of base emulsion are listed in Table 6.

² Zonyl^® is a registered trademark of Dupont (Wilmington, DE) and is a fluoro additive powder with an average agglomerate size of 1.8 to 4 μm.

The invention being thus described, it will be evident to those skilled in the art that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention and all such modifications are intended to be included within the scope of the claims.

Claims

WHAT IS CLAIMED

1. A lubricious sealant composition comprising: a curable resin component; and a lubricious agent incorporated therein which imparts lubricity to a cured surface of said composition.

2. The composition of claim 1, wheein said curable resin component is an elastomer.

3. The composition of claim 1, wherein said curable resin component is a silicone.

4. The composition of claim 3, wherein said silicone resin is curable through moisture, radiation, heat or a combination thereof.

5. The composition of claim 1, wherein said curable resin component is heat curable.

6. The composition of claim 1, wherein said curable component is a water-based emulsion.

7. The composition of claim 1, wherein said curable component is an urethane- acrylate emulsion.

8. The composition of claim 1 further including an initiator

9. The composition of claim 8, wherein said initiator is a metal insensitive initiator.

10. The composition of claim 9, wherein said initiator is selected from the group consisting of an azo compound, a vazo compound, a peroxyketal and combinations thereof.

11. The composition of claim 9, wherein said initiator is selected from the group consisting of 2,2'-azobis [2-methyl-N-(2-hydroxy) propionamide], azobis-2-methylbutyro nitrile and combinations thereof.

12. The composition of claim 1, wherein said lubricious agent is selected from the group consisting of polyethylene, polytetrafluoroethylene, talc, graphite, boron nitride, perfluoropolyethers, molybdenum disulfide, tungsten disulfide, calcium fluoride, graphite fluoride, and combinations thereof.

13. The composition of claim 1, wherein said lubricious agent is in particulate form.

14. The composition of claim 1, wherein said lubricious agent is present in an amount from about 0.1% to about 60% by weight of the total composition.

15. The composition of claim 1, wherein the lubricious agent is a material selected from the group consisting of liquids and waxes.

16. The composition of claim 15, wherein the liquid lubricious agent is polybutene or hydrogenated polybutene.

17. The composition of claim 15, wherein the lubricious wax material is a polyethylene or polypropylene wax.

18. The composition of claim 1, wherein said curable component is present in an amount from about 40% to about 95% by weight of the total composition.

19. The composition of claim 8, where said initiator is present in an amount from about 0.1% to about 10.0% by weight of the total composition.

20. A method of imparting surface lubricity to an article comprising providing a lubricious sealant composition to said surface of said article, said sealant composition comprising: a heat curable component capable of forming a substantially dry, adherent film prior to cure; a lubricious agent within said heat curable component; and an initiator.

21. The method of claim 20, wherein said heat curable component is selected from the group consisting of water-based emulsions.

22. The method of claim 20, wherein said lubricious agent is selected from the group consisting of polyethylene, polytetrafluoroethylene, talc, graphite, boron nitride, perfluoropolyethers, molybdenum disulfide, tungsten disulfide, calcium fluoride, graphite fluoride, and combinations thereof.

23. The method of claim 20, wherein said lubricious agent is present in about 0.1% to about 60%) by weight of the total composition.

24. A lubricious sealant composition comprising the reaction product of: (i) a curable component;

(ii) an initiator for said curable component; and

(iii) a lubricious agent capable of increasing the lubricity of the surface of said curable component.

25. An article comprising: a resin component; and a lubricous sealant composition incorporated therein, said lubricous sealant composition comprising: a water-based heat curable emulsion component; a lubricious agent; and an initiator.

26. The article of claim 25, wherein said article is a member selected from the group consisting of gaskets, hoses, hose housings and o-rings.

27. The article of claim 25, wherein said resin component is curable by a moisture cure mechanism, heat cure mechanism, photo initiator mechanism and combinations thereof.

28. The article of claim 25, wherein said lubricious agent is selected from the group consisting of polyethylene, polytetrafluoroethylene, talc, graphite, boron nitride, perfluoropolyethers, molybdenum disulfide, tungsten disulfide, calcium fluoride, graphite fluoride, and combinations thereof.