INJECTION MOLDING PROCESS, APPARATUS AND MATERIAL FOR FORMING CURED-IN-PLACE GASKETS

FIELD

The present disclosure relates to a process for forming a cured-in-place gasket by liquid injection molding. More particularly, the present disclosure relates to a low pressure and room temperature process and equipment for forming a cured-in-place gasket by liquid injection molding.

BRIEF DESCRIPTION OF RELATED TECHNOLOGY

Cured-in-place gaskets have been formed by liquid injection of a gasket-forming material into a mold. Typical processes include the use of high temperature and/or high pressure liquid injection. For example, a typical process is described in U.S. Pat. No. 5,597,523 to Sakai et al. The molding process and molding device requires use of both an elevated pressure of 24,500 kPa (3,500 psig) and an elevated temperature of 250° C. (480° F.). Upper and lower molds are mated to one to define a mold cavity therebetween. Liquid gasket material, such as epoxy resin or plastic rubber, is pumped into a mold cavity at 2,900 kPa (430 psig). The molds and the gasket material are heated to about 250° C. (480° F.). The gasket material in pumped into the mold cavity. The molds are then clamped together at the elevated pressure of 24,500 kPa (3,500 psig). After the gasket material is cured, the molds and the gasket are cooled to room temperature. The process is described as requiring about one minute to inject and cure the gasket material. The use of such elevated pressures and temperatures at such short cycle times, however, require the use of metallic molds that can withstand such large fluctuations in pressure and temperature while maintaining close tolerances to form the gasket, which make the apparatus and the process expensive and difficult to operate.

U.S. Pat. No. 6,387,303 to Jones et al. describes a molding process and apparatus that avoid the use of elevated temperatures through the use of a gasket-forming material, which is curable at room temperature. The molds and the gasket-forming material is described as being cooled to about 0° C. (32° F.) to avoid polymerization of the room-temperature curable material. The gasket-forming material is described as being a room-temperature curable silicone rubber or an anaerobically curing acrylate compound, which uses temperature cycling to form the gasket.

Thus, there is need for a method for forming gaskets, which does not require the use of high pressures and does not require the cycling of temperatures away from room temperature. There is also a need for actinic radiation curable compositions useful to form gaskets under such conditions.

SUMMARY

In one aspect, a method for producing a gasket by liquid injection is provided. The method comprises the steps of providing an actinic radiation curable functionalized poly(meth)acrylate composition; providing an injection mold defining an enclosed gasket-forming cavity and an injection port communicating with the cavity, the mold comprising actinic radiation-conducting means for permitting actinic radiation transmission therethrough; injecting the composition into the mold at temperatures of about 65° C. (150° F.) or less and a pressure of about 1,030 kPa (150 psig) or less to fill the cavity; and transmitting actinic radiation through the radiation-conducting means in a sufficient amount to cure the composition in the mold to form a gasket in the gasket-forming cavity.

In another aspect, the actinic radiation conducting means may comprise a mold surface which transmits actinic radiation directly therethrough to cure the composition. Desirably, at least a portion of the mold wall comprises a light-transmitting plastic or glass mold.

In still another aspect, the actinic radiation conducting means may comprise radiation-conducting channels, which conduct radiation through the mold to the actinic radiation-curing composition. Desirably, the actinic radiation conducting means comprises optic fibers.

Desirably, the injection temperature is from about 10° C. (50° F.) to about 66° C. (150° F.). More desirably, the injection temperature is from about 20° C. (68° F.) to about 50° C. (120° F.), including temperatures from about 20° C. (50° F.) to about 25° C. (77° F.). Even more desirably, the injection temperature is at about room temperature.

Desirably, the injection pressure is from about 140 kPa (20 psig) to about 1,030 kPa (150 psig). More desirably, the injection pressure is less than or equal to about 620 kPa (90 psig), for example, from about 345 kPa (50 psig) to about 620 kPa (90 psig).

Desirably, the radiation exposure lasts for about 5 minutes of less and desirably is predominantly radiation in the UV and/or visible range of the electromagnetic spectrum.

In yet another aspect, the poly(meth)acrylate composition may comprise a (meth)acrylate-functionalized poly(acrylate), such as one terminated by (meth)acrylate and including n-butyl acrylate as a segment of the backbone.

Desirably, the poly(meth)acrylate composition is extrudable at a rate of about 50 g/minute to about 500 g/minute, such as through a nozzle having a diameter in the range of about 0.8 mm ( 1/32 of an inch) to about 9.5 mm (⅜ of an inch), such as 3.2 mm (⅛ of an inch), at a pressure in the range of about of about 140 kPa (20 psig) to about 830 kPa (120 psig), such as of about 690 kPa (90 psig) or less.

Desirably, the poly(meth)acrylate composition has a viscosity of about 100 Pas (10,000 cPs) to about 1,000 Pas (100,000 cPs).

Desirably, the poly(meth)acrylate composition includes one or more monofunctional monomers present in a combined amount of about 8% to about 20% by weight of the total composition.

In another aspect, a system for forming a gasket composition at room temperature by low-pressure liquid injection is provided. The system comprises at least first and second mold members having opposed mating surfaces, wherein at least one of the mating surfaces has a cavity in the shape of a gasket, and at least one of the mold members comprises a port in fluid communication with the cavity and wherein at least one of the mold members transmits actinic radiation therethrough; and a source of actinic radiation, the actinic radiation generated therefrom being transmittable to the cavity when the opposed mating surfaces are disposed in substantial abutting relationship.

In a further aspect, the second mold member is a part, such as but not limited to a valve cover or oil pan, where the gasket is adhered by mechanical and/or chemical means to a sealing surface of the second mold member. When the first mold member is removed from the assembly, the gasket stays in place on the second mold member to provide a final assembly comprising an integral gasket. Such an assembly has an advantage over typical cure-in-place assemblies in that gasket aspect ratios and/or gasket cross sectional shapes can be provided that are not possible with the cure-in-place method. As compared to press-in-place gaskets, the present process eliminates the need to separately form a gasket and subsequently press or otherwise place the gasket on the part in a separate operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of a mold having a top and a bottom mold member for forming a gasket in accordance with the present disclosure.

FIG. 2 is a cross-sectional view of the mold of FIG. 1 taken along the 2-2 axis.

FIG. 3 is an exploded view of the mold of FIG. 2 depicting the top mold member and the bottom mold member.

FIG. 4 is a top view of the bottom mold member of FIG. 3 taken along the 4-4 axis.

FIG. 5 is, a left elevational view of the bottom mold member of FIG. 4 taken along the 5-5 axis.

FIG. 6 is a right elevational view of the bottom mold member of FIG. 4 taken along the 6-6 axis.

FIG. 7 a cross-sectional view of the bottom mold member of FIG. 4 taken along the 7-7 axis.

FIG. 8 is a perspective view of the top mold member of FIG. 1 depicting the top mold member having transparent material.

FIG. 9 is a cross-sectional view of the transparent top mold member of FIG. 8 taken along the 9-9 axis.

FIG. 10 is a perspective view of the top mold member of FIG. 1 having light transmissible conduits therethrough.

FIG. 11 is a cross-sectional view of the top mold member of FIG. 10 taken along the 11-11 axis depicting the conduits traversing through the top mold member.

FIG. 12 is a partial side elevational view of another aspect of the top mold member of FIG. 11 depicting a light transmissible conduit terminating at a transparent portion of the top mold member.

FIG. 13 is a partial side elevational view of another aspect of the top mold member of FIG. 11 depicting a light transmissible conduit disposed within a transparent portion of the top mold member.

FIG. 14 is a schematic illustration of a light source in communication with the top mold member of the present disclosure.

FIG. 15 is a schematic, partially cross-sectional view of one embodiment of a mold assembly of the present disclosure.

FIG. 16 is schematic, partially cross-sectional view of one embodiment of a mold assembly including spot curing.

FIG. 17 is a schematic view of the mold of FIG. 15 through the frame and lower mold member.

DETAILED DESCRIPTION

Use of the terms “upper” and “lower” is for the convenience of the reader and is not meant to be limiting with respect to the position of components described by those terms.

In one embodiment a mold 10 is used for forming cured-in-place gaskets. The mold 10 includes an upper mold member 12, a lower mold member 14. Mold 10 can include more than two mold members if desired. The mold members 12, 14 each have a mating surface 13, 15 respectively. One or both mold members define a mold cavity 18 in the mating surface thereof. When mold members 12, 14 are aligned, mold surfaces 13, 15 are in abutting relationship fluidly sealing mold cavity 18 between the mold surfaces 13, 15. An injection port 16 is in fluid communication with the mold cavity 18. The injection port 18 can be defined in either mold member as convenient to mold design and use. Due to the low pressure, i.e., less than about 690 kPa (100 psi), and low temperature, i.e., at about room temperature, operation of the present process, the mold 10 avoids the need for mold members having materials suitable for higher pressures and temperatures. Such materials, such as stainless steel, are often more expensive and more difficult to machine or tool into the mold. Desirably, the mold members 12, 14 of the present process may suitably be formed from less expensive materials, such as plastics, glass or aluminum. The plastics may include thermoformed plastics.

As used herein the term “room temperature” and its variants refer ambient temperature typical of industrial settings. Such ambient temperatures are often of a greater range than common usage of the term “room temperature”, i.e. from about 20° C. (68° F.) to about 25° C. (77° F.). For example, industrial settings may have ambient temperatures from about 10° C. (50° F.) to about 40° C. (100° F.).

FIG. 1 is a perspective view of one embodiment of mold 10. The mold 10 includes upper mold member 12, lower mold member 14, and injection port 16, inter-related as shown. As depicted in FIG. 4, the injection port 16 is in fluid communication with the mold cavity 18.

FIG. 2 is a cross-sectional view of the mold 10 of FIG. 1 taken along the 2-2 axis. As depicted in FIG. 2, the upper mold member 12 includes a mold cavity 18. Liquid gasket-forming compositions may be introduced into the mold cavity 18 via the injection port 16.

FIG. 3 is a partial-break-away view of the mold 10 of FIG. 2. Mold member 12 includes a mating surface 13, and mold member 14 includes a mating surface 15. The mold members 12 and 14 may be aligned to one and the other, as depicted in FIG. 2, such that the mating surfaces 13 and 15 are substantially juxtaposed to one and the other. As depicted in FIG. 3 a gasket 17 is removed from the mold cavity 18 and attached to the mating surface 15.

As depicted in FIG. 4, the top view of the mold cavity 18 is in the shape of a closed perimetric design. Although mold cavity 18 is depicted as a rounded rectangle in FIG. 4, the present disclosure is not so limited and other shaped cavities may suitably be used. Further, while the cross-sectional shape of the mold cavity 18 is depicted as being circular or semi-circular in FIG. 2, the present disclosure is not so limited. Because the mold provides support to the uncured gasket composition until curing, complex seal geometries and shapes, for example incorporating high, slender sections or multiple spaced seal lips, can be formed. Such shapes are not possible with conventional cure in place methods that do not support the uncured gasket composition. Moreover, the present disclosure is not limited to having the mold cavity 18 in only the upper mold member 12, and either or both mold members 12, 14 may suitably contain the mold cavity.

As depicted in FIG. 4, the mold 12 may contain a second port 20. The second port 20 is in fluid communication with the mold cavity 18. The second port 20 may be used to degas the cavity 18. As the gasket-forming material is introduced into the cavity 18 via the port 16, air may escape via the second port 20 to degas the mold cavity 20. The size of the second port 20 is not limiting. Desirably, the size, i.e., the cross-section extent, of the second port 20 is minimized to allow for the egress of air, but small enough to limit liquid flow of the gasket-forming material therethrough. In other words, the size of the second port 20 may be pin-hole sized where air can flow through while inhibiting substantial flow of liquid gasket-forming material. Further, the present process is not limited to the use of a single port 16 or a single port 20, and multiple ports may be used for the introduction of the gasket material and/or the venting of air.

It can be useful in some applications to fluidly connect an evacuation device to port 20. The evacuation device can be used to provide a reduced or sub-ambient pressure in cavity 18 to degas the cavity 18 before or during filling with the gasket-forming material. The reduced pressure used is not limited and can be varied to accommodate cavity dimension and configuration, composition and physical properties of the curable composition and injection cycle. Reduced pressures of about 2 inches to about 20 inches of mercury, for example 14 to 18 inches of mercury, have been advantageously used in some applications. In some applications it can be useful to vary the reduced pressure applied to the cavity during the injection and/or cure cycles.

FIG. 5 is a cross-sectional view of the mold member 12 taken along the 5-5 axis of FIG. 4. As depicted in FIG. 5, the injection port 16 may suitably be a cavity or bore in the mold member 12. The portion of the injection port 16 may be threaded (not shown) or have a valve (not shown) or a tubing or a hose (not shown) through which the gasket-forming material may be delivered.

FIG. 6 is a cross-sectional view of the mold member 12 taken along the 6-6 axis of FIG. 4. As depicted in FIG. 6, the port 20 may suitably be a cavity or bore in the mold member 12. The portion of the port 20 may have a valve (not shown) for controlling the egress of air and/or gasket-forming material.

FIG. 7 is a cross-sectional view of the mold member 12 taken along the 7-7 axis of FIG. 4. The mold cavity 18 is depicted as extending into the mold member 12 at its mating surface 13.

FIG. 8 is a perspective view of the mold member 12 depicting that the mold member 12 may be made of or may comprise an actinic radiation transparent material. As used herein an actinic radiation transparent material is a material that is transparent or transmissible or substantially transmissible to actinic radiation, for example ultraviolet (UV) radiation, such that actinic radiation from a source will move through the material in sufficient amount to cure a curable compound on an opposing side of the material in a commercially reasonable time such as, for example, 5 minutes or less or desirably 1 minute or less or advantageously 30 seconds or less. Examples of actinic radiation transparent materials include some glasses and some polymers such as cured silicone rubber. A cross-sectional view of one embodiment of a transparent mold member 12 is depicted in FIG. 9.

In another aspect of the present, one of the mold members having the gasket-shaped cavity is itself an article of manufacture or a part of an article of manufacture, such as an portion of a vehicle, for example a valve cover. The disclosed compositions may be formed directly on such an article of manufacture or a part thereof by the methods of the present disclosure. Thus, upon curing the gasket-forming compositions and removing the actinic radiation-conducting-mold member, the article or part is produced with an integral gasket, which eliminates the need for mechanically and/or chemically attaching a separately formed gasket.

FIG. 15 is a cross sectional view of one embodiment of a mold 10 comprising mold member 12 and mold member 14. Mold member 12 is an article of manufacture or part thereof having a predefined sealing surface 34 to which a gasket will be molded. Mold member 14 comprises a base 36 and an overlying polymeric liner 38. Both the base 36 and liner 38 are transparent, i.e., substantially transmissible, to actinic radiation, for example ultraviolet (UV) radiation. The base 36 can be generally rectangular with spaced, planar major surfaces 40, 42 defining a thickness selected to provide support for the liner 38 during the molding process. The base 36 typically will not include cavity 18. The base 36 can be, for example, glass. The liner 38 will have a generally planar support surface 44 adjacent one base major surface 40 and an opposing molding surface 46 defining cavity 18. The liner 38 can be, for example, cured silicone rubber. The base 36 and liner 38 are supported by a peripheral frame 50. The interior portion of the frame 50 is open to allow transmission of actinic radiation through the base 36 and liner 38 to the uncured composition in the cavity 18. FIG. 17 schematically illustrates a view through the open interior portion one embodiment of a frame 50 to mold member 14, cavity 18 and mold member 12 (shown in the oval opening of liner 38) during injection of curable composition into the cavity 18. The darker colored portion of cavity 18 is filled with curable composition while the lighter colored portion of cavity 18 has not yet been filled. With reference to FIG. 15, a retainer 52 is secured to the frame 50, for example by mechanical fasteners 54 over the liner 38 to hold the base 36 and liner 38 in place. The frame 50 and retainer 52 can be made from, for example, metal, composites or plastic. The actinic radiation opaque article of manufacture 12 is placed adjacent liner 38 with the part sealing surface 34 in contact with the liner molding surface 46. Contact of sealing surfaces 34, 46 encloses cavity 18. Liner cavity 18 can be aligned with a corresponding cavity in the article sealing surface if desired. Mold member 12 is removably secured to mold member 14, for example by clamps 56, so that sealing surfaces 34, 46 remain sealingly engaged to maintain a fluidly sealed cavity 18 during the molding process. The article 12 has one or more ports 16, 20 fluidly connected to the cavity 18. Curable composition can be supplied from a container through lines 58 to a nozzle 60. The nozzle 60 is selectively fluidly engageable to port 16 or 20 to allow controlled injection of curable composition through port 16 or 20 into cavity 18. A separate nozzle can be used to control degassing through port 20.

FIG. 10 is a perspective view of mold member 12′ depicting one or more holes or conduits 24 therethrough. As depicted in FIG. 11 which is a cross-section view of the mold member 12′, the conduits 24 may extend completely through the mold member 12′. As depicted in FIGS. 10 and 11, the mold member 12′ need not be made of transparent material as the conduits 24 may allow the transmission of the curing UV light or curing actinic radiation (not shown). The present process, however, is not so limiting. For example as depicted in FIG. 12, the conduit 24 need not extend entirely through the mold member 12′. The conduit 24 may extend only partially through the mold member 12′. Desirably, the portion 12b of the mold member 12′ below the conduit 24 is made of transparent material to permit the transmission of actinic radiation therethrough. As depicted in FIG. 12, the remaining portion 12a of the mold member 12′ need not be made of a transparent material. Further, the present process is not limited to partially extending conduits 24 having transparent material 12b proximally located just at the terminus of the conduit 24. For example, as depicted in FIG. 12, significant portions of the mold member 12′ may comprise transparent material 12b. Desirably, a top portion 15 of, the mold member 12′ comprises non-transparent material 12a.

Actinic radiation, such radiation in the visible and/or UV range of the electromagnetic spectrum passes through one or both molds to initiate cure of uncured composition in the cavity 18. One system for delivering actinic radiation is schematically depicted in FIG. 14. A light source 26 generates actinic radiation, such radiation in the visible and/or UV range of the electromagnetic spectrum. The actinic radiation passes through fiber optic cable 28. The cable 28 may be positionable within the mold member 12, 12′. The cable 28 may further include a light guide 30 for releasably securing the light source or cable 28 with the mold member 12.

In one aspect at least one of the two mold members 12, 14 is an actinic radiation transmissible member and the actinic radiation is transmitted through the transmissible member. The amount of actinic radiation transmitted through the transmissible member and onto said liquid composition may be detected and monitored. The amount of actinic radiation transmitted onto the liquid composition may be increased when the actinic radiation level declines to a preset minimum. The mating surface of the transmissible member may be simply cleaned when the radiation level declines to the preset minimum to increase actinic radiation transmittance therethrough. Alternatively, the amount of actinic radiation may be controlled by providing the mating surface of the transmissible member with a first removable liner; removing the first removable liner when the radiation level declines to the preset minimum; and providing a second removable liner at the mating surface of the transmissible member to increase actinic radiation transmittance therethrough.

In another system for delivering actinic radiation shown in FIG. 16 a light source 26 generates actinic radiation. The actinic radiation passes through fiber optic cables 28 and is focused in selected areas to spot cure composition in the selected area before curing composition in the cavity 18. Curable composition away from the fiber optic cables 28 will not receive sufficient actinic radiation to cure.

One embodiment of a method for producing a gasket by liquid injection molding includes the steps of providing an actinic radiation curable functionalized poly(meth)acrylate composition; providing an injection mold 10 defining an enclosed gasket-forming cavity 18 and an injection port 16 fluidly communicating with the cavity 18, the mold 10 comprising actinic radiation-conducting means for permitting actinic radiation transmission; injecting the composition in the mold at temperatures of about 50° C. (120° F.) or less and a pressure of about 690 kPa (100 psig) or less to fill the cavity 18; and transmitting a curable amount of actinic radiation through the radiation conducting means of the mold 10 to cure the composition into a gasket. The mold 10 may include at least two members 12, 14, with the two members 12, 14 having opposed mating surfaces 13, 15. As the composition is pumped or otherwise pressurized into the mold cavity 18, the composition may exhibit a higher temperature, i.e., about 50° C. (120° F.) or less, than ambient temperature due to frictional considerations. Temperatures used in this method are below the thermal polymerization temperature of the composition and are not sufficient to cure the composition.

Prior to the injecting of the liquid composition the mating surfaces 13, 15 of the mold members 12, 14, respectively, are aligned to define the mold cavity 18. After aligning the mold members 12, 14 may be secured to one and the other prior to the step of injecting the gasket-forming composition.

The method of this aspect may further include the step of degassing the cavity prior to injecting or while injecting the liquid, actinic radiation curable, gasket-forming composition. Desirably, the step of degassing includes degassing through the second port 20, which is in fluid communication with the cavity 18. An evacuation device such as a vacuum source or vacuum pump may be fluidly connected to the cavity 18 to provide a reduced or sub-ambient pressure therein.

The liquid composition fully fills the cavity 18 without the need for excessive liquid handling pressures, i.e., pressures substantially above 690 kPa (100 psig). Desirably, the liquid composition fully fills the cavity 18 at a fluid handling pressure of about 690 kPa (100 psig) or less.

After the composition is cured or at least partially cured, the mold members 12, 14 may be released from one and the other to expose the gasket, after which the gasket may be removed from the mold cavity 18.

One embodiment of a method for producing a gasket by liquid injection molding includes the steps of providing a mold member 14 comprising a generally planar base 36 and a polymeric liner 38 supported by the base and defining a cavity 18 in a molding surface 46; providing a mold member 12 comprising an article of manufacture having a predefined sealing surface 34 and an injection port 16; securing the article sealing surface 34 to the liner molding surface 46 so that the injection port 16 is fluidly connected to the now sealed cavity 18; injecting an actinic radiation curable functionalized poly(meth)acrylate composition through the injection port 16 to fill the cavity 18; and transmitting a curable amount of actinic radiation through the base 36 and liner 38 to cure the composition in sealed cavity 18 into a gasket that is bonded to the article sealing surface 34.

One embodiment of a method for producing a gasket by liquid injection molding includes the steps of providing mold members 12, 14, wherein one or both of the mold members define a cavity 18 and a plurality of ports 16, 20; securing mold members 12, 14 together so that the injection port 16 and second port 20 are each fluidly connected to the cavity 18; injecting a small amount of actinic radiation curable functionalized poly(meth)acrylate composition through the second port 20 wherein the amount is not sufficient to fill the cavity 18; and subsequently injecting an amount of actinic radiation curable (meth)acrylate functionalized poly(meth)acrylate composition through the injection port 16, wherein the amount is sufficient to fill the cavity 18; and transmitting a curable amount of actinic radiation to cure the composition enclosed in cavity 18 into a gasket. The amount of composition remaining in cavity 18 after injection through port 20 should be sufficient to fill only about 1% to about 50%, for example about 2% to about 10% of the cavity volume adjacent to port 20 and can be about 3 to about 10 grams depending on dimensions of cavity 18. This can be done by injecting only this amount or injecting excess material through port 20 and subsequently removing some of the injected composition during degassing. In some conditions it has been found that when the composition is forced through port 16 into cavity 18 an air bubble is left in the cavity 18 adjacent port 20. After curing the air bubble undesirably forms a void in the finished gasket. Pre-injecting a small amount of composition through port 20 and into cavity 18 lessens the possibility of air bubble formation at this location.

One embodiment of a method for producing a gasket by liquid injection molding includes the steps of providing mold members 12, 14, wherein one or both of the mold members define a cavity 18 and a plurality of ports 16, 20; securing mold members 12, 14 together so that the injection port 16 and second port 20 are each fluidly connected to the cavity 18; injecting an actinic radiation curable functionalized poly(meth)acrylate composition through the injection port 16 to fill the cavity 18; transmitting an amount of actinic radiation through one or both mold members 12, 14 in the area of the injection port 16 and/or second port 20, wherein the amount of transmitted radiation is sufficient to at least partially cure the composition in the port area but not cure all of the composition in the cavity 18; and subsequently transmitting a curable amount of actinic radiation through the mold members 12, 14 to substantially cure the composition into a gasket. As shown best in FIG. 16 transmission of actinic energy to selected areas of the cavity 18 can be accomplished by using fiber optic cables 28 to focus actinic radiation from a source 26 to the selected portions of the mold 14. Actinic radiation from the fiber optic cable 28 can pass through mold 14 (comprising base 36 and liner 38 in this embodiment) to curable composition in selected portions of the cavity 18. In some applications an injector nozzle is used to inject composition under low pressure through injection port 16. When the injector is removed a small amount of composition may flow back through injection port 16 and on to the exterior surface of mold member 12. This composition is not fully cured and can be objectionable. Curing the composition in the port area forms a semi-solid or solid “plug” that allows the injection nozzle to be removed but blocks composition from moving through the port after injection nozzle removal. Subsequent curing of composition in the entire cavity 18 forms the finished gasket.

In other embodiments combinations of method features can be used to provide desired results. For example, mold member 12 can be an article of manufacture and mold member 14 can comprise a base 36 and polymer liner 38 as previously described. Curable composition can be injected through port 16 or through port 16 with a small amount through port 20. The composition can be spot cured in the area of port 16 and/or port 20 before removal of the injector nozzles. Composition in the remainder of cavity 18 is subsequently cured by exposure to actinic radiation.

Desirably, the gasket-forming material has an extrusion rate of about 50 g/min to about 500 g/min through a 3.2 mm (0.125 inch) nozzle at a pressure of about 620 kPa (90 psig). More desirably, the liquid composition has an extrusion rate of about 100 g/min to about 200 g/min through a 3.2 mm (0.125 inch) nozzle at a pressure of about 620 kPa (90 psig).

The extrusion rate may be determined by industry standard techniques. For example, a testing apparatus may include a sealant gun (Semco® model 250 or equivalent), a cartridge (Semco® model 250-C6 or 250-C8 or equivalent), and a nozzle with a 3.2 mm (0.125 inch) orifice (Semco® 440 or equivalent). Such devices and assemblies thereof are commercially available from Semco Application Systems, Glendale, Calif. After placing the liquid composition in the cartridge, pressure within the cartridge is controlled at 620 kPa (90 psi). The extrusion rate is then determined by weighing the amount of material passed through the nozzle at 620 kPa (90 psi) after 15 seconds.

Compositions with higher extrusion rates are more difficult to process at the low injection pressure of about 690 kPa (100 psig) or less. Composition with lower extrusion rates may not adequately fill the cavity and properly form a gasket therein. Desirably, the liquid composition has a viscosity from about 0.01 Pas (10 centipoise or cPs) to about 1,000 Pas (1,000,000 cPs) at 25° C. (77° F.). In some applications the liquid composition desirably has a viscosity from about 100 Pas (10,000 cPs) to about 2,000 Pas (200,000 cPs). More desirably for the liquid injection molding process disclosed herein the liquid composition has a viscosity from about 100 Pas (10,000 cPs) to about 1,000 Pas (100,000 cPs).

Desirably, the liquid composition is cured at or about room temperature within about 5 minutes or less. More desirably, the liquid composition is cured within 1 minute or less, for example, cured within 30 seconds or less.

The actinic radiation curable composition may be a one-part liquid composition, which may optionally include a volume expansion agent so as to produce a foamed gasket.

Useful materials to form gaskets for the actinic radiation curable composition include actinic radiation curable siloxanes, polyacrylates, polyurethanes, polyethers, polyolefins, polyesters, copolymers thereof and combinations thereof. Advantageously, the actinic radiation curable material includes a (meth)acrylate functionalized poly(meth)acrylate composition. Desirably, the curable material includes a (meth)acryloyl functionalized material having at least two (meth)acryloyl pendant groups. Desirably, the (meth)acryloyl pendant group is represented by —OC(O)C(R¹)═CH₂, where R¹is hydrogen or methyl. More desirably, the liquid gasket-forming material is a (meth)acryloyl-terminated poly acrylate. The (meth)acryloyl-terminated poly acrylate may desirably have a molecular weight from about 3,000 to about 40,000, more desirably from about 8,000 to about 15,000. Further, the (meth)acryloyl-terminated poly acrylate may desirably have a viscosity from about 2,000 Pas (200,000 cPs) to about 8,000 Pas (800,000 cPs) at 25° C. (77° F.), more desirably from about 4,500 Pas (450,000 cPs) to about 5,000 Pas (500,000 cPs). Details of such curable (meth)acryloyl-terminated materials may be found in European Patent Application No. EP 1 059 308 A1 to Nakagawa et al., and are commercially available from Kaneka Corporation, Japan, such as under the trade designations RC220C, RC210C, RC200C and RC100C. It is believed that the RC220C, RC210C and RC200C are each terpolymers of combinations of substituted and unsubstituted alkylacrylates, such as ethyl acrylate, 2-methoxyethyl acrylate and n-butyl acrylate (varying by molecular weight), whereas the RC100C is a homopolymer of n-butyl acrylate.

Desirably, the liquid composition includes a photoinitiator. A number of photoinitiators may be employed herein to provide the benefits and advantages to which reference is made above. Photoinitiators enhance the rapidity of the curing process when the photocurable compositions as a whole are exposed to electromagnetic radiation, such as actinic radiation. Examples of suitable photoinitiators for use herein include, but are not limited to, photoinitiators available commercially from Ciba Specialty Chemicals, under the “IRGACURE” and “DAROCUR” trade names, specifically IRGACURE 184 (1-hydroxycyclohexyl phenyl ketone), 907 (2-methyl-1-[4-(methylthio)phenyl]-2-morpholino propan-1-one), 369 (2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone), 500 (the combination of 1-hydroxy cyclohexyl phenyl ketone and benzophenone), 651 (2,2-dimethoxy-2-phenyl acetophenone), 1700 (the combination of bis(2,6-dimethoxybenzoyl-2,4,4-trimethyl pentyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one), 819 [bis(2,4,6-trimethyl benzoyl) phenyl phosphine oxide], 2022 [IRGACURE 819 dissolved in DAROCUR 1173 (described below)] and DAROCUR 1173 (2-hydroxy-2-methyl-1-phenyl-1-propan-1-one) and 4265 (the combination of 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one); and the visible light [blue] photoinitiators, dl-camphorquinone and IRGACURE 784DC. Of course, combinations of these materials may also be employed herein.

Other photoinitiators useful herein include alkyl pyruvates, such as methyl, ethyl, propyl, and butyl pyruvates, and aryl pyruvates, such as phenyl, benzyl, and appropriately substituted derivatives thereof. Photoinitiators particularly well-suited for use herein include ultraviolet photoinitiators, such as 2,2-dimethoxy-2-phenyl acetophenone (e.g., IRGACURE 651), and 2-hydroxy-2-methyl-1-phenyl-1-propane (e.g., DAROCUR 1173), bis(2,4,6-trimethyl benzoyl) phenyl phosphine oxide (e.g., IRGACURE 819), and the ultraviolet/visible photoinitiator combination of bis(2,6-dimethoxybenzoyl-2,4,4-trimethylpentyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (e.g., IRGACURE 1700), as well as the visible photoinitiator bis (η⁵-2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium (e.g., IRGACURE 784DC).

As noted above, useful actinic radiation includes ultraviolet light, visible light, and combinations thereof. Desirably, the actinic radiation used to cure the liquid gasket-forming material has a wavelength from about 200 nm to about 1,000 nm. Useful ultraviolet light (UV) includes, but is not limited to, UVA (about 320 nm to about 410 nm), UVB (about 290 nm to about 320 nm), UVC (about 220 nm to about 290 nm) and combinations thereof. Useful visible light includes, but is not limited to, blue light, green light, and combinations thereof. Such useful visible lights have a wavelength from about 450 nm to about 550 nm.

In addition to the above-described (meth)acrylate functionalized poly(meth)acrylate composition, the composition may further include a (meth)acryloyl-terminated compound having at least two (meth)acryloyl pendant groups selected from (meth) acryloyl-terminated polyethers, meth)acryloyl-terminated polyolefins, (meth)acryloyl-terminated polyurethanes, (meth) acryloyl-terminated polyesters, (meth) acryloyl-terminated silicones, copolymers thereof, and combinations thereof.

The compositions may further include reactive diluents, rubber toughening agents, fillers such as silica fillers, antioxidants and/or mold release agents.

As the reactive diluent, the composition may include a monofunctional (meth)acrylate. Useful monofunctional (meth)acrylates may be embraced by the general structure CH₂═C(R)COOR²where R is H, CH₃, C₂H₅or halogen, such as Cl, and R²is C_1-8mono- or bicycloalkyl, a 3 to 8-membered heterocyclic radial with a maximum of two oxygen atoms in the heterocycle, H, alkyl, hydroxyalkyl or aminoalkyl where the alkyl portion is C_1-8straight or branched carbon atom chain. Among the specific monofunctional (meth)acrylate monomers particularly desirable, and which correspond to certain of the structures above, are hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, methyl methacrylate, tetrahydrofurfuryl methacrylate, cyclohexyl methacrylate, 2-aminopropyl methacrylate, isobornyl methacrylate, isodecyl methacrylate, 2-ethyl hexyl methacrylate and the corresponding acrylates.

In addition, N,N-dimethyl acrylamide (“DMAA”) acrylic acid, and β-carboxyethyl acrylate (such as is available commercially from Rhodia under the tradename SIPOMER) are usefully employed in the practice of the present process.

Commercially available representative examples of such reactive diluents include those used in the samples below. More specifically, SARTOMER SR395 (isodecyl acrylate, commercially available from Sartomer Company, Inc., Exton, Pa.), SARTOMER SR495 (caprolactone acrylate, commercially available from Sartomer), SARTOMER SR531 (cyclic trimethylolpropane formal acrylate, commercially available from Sartomer), and SARTOMER PRO6622 (3,3,5 trimethylcyclohexyl acrylate, commercially available from Sartomer) are each appropriate choices, either alone or in combination with each other or with the other noted reactive diluents.

When used, the reactive diluent should be used in the range of 0.5 to about 50 percent by weight, such as about 5 to about 30 percent by weight.

The compositions may also include rubber toughening agents, such as those used in the samples below. More specifically, commercially available ones include VAMAC DP (an ethylene acrylic dipolymer elastomer available commercially from DuPont), HYCAR VTBN (methacrylate-functional acrylonitrile-butadiene-copolymers commercially available from Hansa Chemie), HYPALON 20 (commercially available from DuPont, and reported to be greater than 96% chlorosulfonated polyethylene, less than 0.4% carbon tetrachloride, less than 0.04% chloroform and less than 2% talc), NEOPRENE AD-10 (commercially available from DuPont, and reported to be greater than 98% 2-chloro-1,3-butadiene polymers and copolymers, less than 1% water and less than 1% talc), NIPOL IR2200L (commercially available from Zeon, and reported to be greater than 99% polyisoprene polymer), RICACRYL 3100 (commercially available from Sartomer and reported to be a methacrylated polybutadiene low-functional UV-curable resin), and combinations thereof.

When used, the rubber toughening agent should be used in the range of about 0.5 to about 30 percent by weight, such as about 2.5 to about 10 percent by weight.

As the filler, the composition may include silica fillers, such as those available commercially from Cabot Corporation under the tradename CABOSIL or from Wacker under the tradename HDK-2000, each of which are represented in the samples below.

When used, the filler should be used in the range of about 0.5 to about 30 percent by weight, such as about 5 to about 20 percent by weight.

As the antioxidant, the composition may include those available commercially from Ciba Specialty Chemicals under the tradename IRGANOX, representations of which are seen in the several examples in the samples below.

When used, the antioxidant should be used in the range of about 0.1 to about 5 weight percent, such as about 0.3 to about 1 weight percent.

As the mold release agent, the composition may include those available commercially for instance from Crompton Corporation under the tradename MOLD-PRO678 (a powdered stearic acid).

When used, the mold release agent should be used in the range of about 0.1 to about 5 weight percent, such as about 0.25 to about 0.5 weight percent.

Optionally, or alternatively, a mold release agent may be applied to the cavity 18 prior to the introduction of the liquid composition. The release agent, if needed, helps in the easy removal of the cured gasket from the mold cavity. Useful mold release compositions include, but are not limited, to dry sprays such as polytetrafluoroethylene, and spray-on-oils or wipe-on-oils such as silicone or organic oils. Useful mold release compositions include, but are not limited, to compositions including C₆to C₁₄perfluoroalkyl compounds terminally substituted on at least one end with an organic hydrophilic group, such as betaine, hydroxyl, carboxyl, ammonium salt groups and combinations thereof, which is chemically and/or physically reactive with a metal surface. A variety of mold releases are available, such as those marketed under Henkel's FREKOTE brand. Additionally, the release agent may be a thermoplastic film, which can be formed in the mold shape.

In another aspect, the poly(meth)acrylate composition may optionally include from about 0% to 90% poly(meth)acrylate polymer or copolymer, from about 0% to about 90% poly(meth)acrylate polymer or copolymer containing at least 2(meth)acrylate functional; from about 0% by weight to about 90% by weight monofunctional and/or multifunctional (meth)acrylate monomers; from about 0% by weight to about 20% by weight photoinitiator; from about 0% by weight to about 20% by weight additives, such as antioxidants; from about 0% by weight to about 20% by weight fillers, such as fumed silica; from about 0% by weight to about 20% by weight rheology modifier; from about 0% by weight to about 20% by weight adhesion promoter; and/or from about 0% by weight to about 20% by weight fluorescent agents or pigments.

More specifically, it is desirable for the composition to be used for forming cured-in-place gaskets to be actinic radiation curable and to include from about 40% to 90% (meth)acrylate-functionalized poly(meth)acrylate polymer; from about 0.5% to about 50% reactive diluent; from about 0.5% to about 10% photoinitiator; and from about 0.5% to about 30% silica filler, wherein the percentages are based on weight percent of the total composition, wherein the composition possesses a viscosity appropriate to permit injection at an injection pressure of about 1,030 kPa (150 psig) or less, and wherein the composition when cured by exposure to radiation in the visible range of the electromagnetic spectrum demonstrates a Durometer, Shore A in the range of 50 to 85+/−5, tensile strength in the range of 7.5 to 9.0 MPa, elongation in the range of 75 to 250 and modulus at 100% elongation of 2.5 to 3.4 Mpa and a compression set after 70 hours at 150° C. in the range of 25 to 60 percent.

In another aspect, an apparatus for forming a gasket at room temperature by liquid injection molding is provided. The apparatus comprises a load position for providing mold members 12, 14 to the apparatus; a position for securing mold members 12, 14 together to form a cavity 18 and ports 16, 20 fluidly connected to the cavity; a position for injecting curable composition through ports 16 and/or 20 into the cavity 18 and optionally degassing the cavity 18; a position for transmitting actinic radiation to the curable composition in the cavity 18 formed by secured mold members 12, 14 to cure the composition; and an unload position to separate mold members 12, 14 and release the cured gasket from cavity 18. The apparatus may also include conventional equipment to accomplish features of the described methods such as cartridge guns, pumps, lines, injection nozzles, etc. to move the curable composition from a storage container such as a cartridge, 5 gallon pail or 55 gallon drum to the cavity 18 at the injection position and a vacuum source, lines, nozzles, etc. to provide reduced pressure in the cavity 18. The apparatus can be arranged so that each operation is manually performed by an operator or so that some or all of the operations are automated. The apparatus can be arranged so that multiple gaskets are formed at one position, e.g. multiple molds or a multiple cavity mold can be injected with curable composition at a single injection position and/or cured in a single actinic radiation transmission position. The apparatus can be arranged so that the positions are combined in one spatial location to form a unitary apparatus. The apparatus can also be arranged so that one or more positions are spatially separated from another position. For example, the load and unload positions may be separated from the injection position and/or the actinic radiation transmission (cure) position. In this arrangement an operator separates secured mold members 12, 14 to release a cured gasket and loads a first set of mold members in one position; the mold members 12, 14 can be secured in the load/unload position; the secured mold members move to the injection position where the cavity 18 is degassed and curable composition is injected; the filled mold members move to an actinic radiation transmission position where composition in cavity 18 is cured; and the secured mold members 12, 14 with cured gasket therein returns to the load/unload position where the cured gasket is removed and the cycle repeated. The operator can load a second set of mold members in the load/unload position once the first set has moved from that position. Movement from one position to the next can be done manually or using conventional material handling equipment such as a frame or pallet to hold the with secured mold members, conveyors, lifts and/or robots to move the pallets with secured mold members and alignment pins 64 to position the pallet and secured mold members in each position. This arrangement is useful when one of the mold members comprises an article of manufacture to which a gasket is molded.

In one embodiment the apparatus comprises first and second mold members 12, 14 having opposed mating surfaces 13, 15, wherein at least one of the mating surfaces 13, 15 has a cavity 18 in the shape of a gasket and a port 16 in fluid communication with the cavity 18 and wherein at least one of the mold members 12, 14 transmits actinic radiation therethrough; and a source of actinic radiation.

The radiation generated from source is transmittable to the cavity 18 when the opposed mating surfaces 13, 15 are disposed in the substantial abutting relationship. The means for transmitting actinic radiation to the cavity may comprise the use of an actinic radiation transmissible member, whereby the actinic radiation is transmitted directly through the member. The actinic radiation transmissible member may be either or both of the mold members 12, 14. The transmissible member or a portion of the transmissible member may be made from a transmissible material, such as glass, polycarbonate, acrylic or other transmissible polymer, and/or may include pathways, such as conduits 24 or fiber optic cables 28, through which the actinic radiation is transmissible or passable.

The apparatus may further include a removable plastic liner abuttingly disposed to the mating surface of the actinic radiation transmissible member, wherein the plastic liner comprises an actinic radiation transmissible material.

EXAMPLES

The examples set forth below provide various samples in which different elastomers are evaluated, different reactive diluents are evaluated, different rubber tougheners are evaluated, different fillers are evaluated, different photoinitiators are evaluated, and different antioxidants are evaluated.

For instance, in Table 1 below, various samples are provided with physical property performance given in Table 1A following thereafter.

TABLE 1

Constituents
Sample No./Amt (wt %)

Type
Identity
1
2
3
4
5

Elastomer
KANEKA RC220C¹
90
70
—
—
—

Polyisoprene
—
—
70
—
—

Diacrylate

BOMAR BR-7432
—
—
—
70
—

GHL²

RAHN GENOMER
—
—
—
—
70

4215³

Rubber
VAMAC DP⁴
—
6.5
6.6
6.5
6.5

Toughener

Antioxidant
IRGANOX 1010⁵
—
0.3
—
0.3
0.3

Reactive
Isobornyl Acrylate
—
13.2
—
13.2
13.2

Diluent
SARTOMER SR395⁶
—
—
13.4
—
—

Silica Filler
CABOSIL TS-530⁷
8
8
8
8
8

Photoinitiator
DAROCUR 4265
2
2
2
2
2

¹An acrylate-functionalized poly(acrylate) available from Kaneka Corporation.

²An aliphatic polyester urethane acrylate available commercially from Bomar Specialties, and having a viscosity of 200,000 cPs @ 50° C., a Tg of −62.0 and when formulated in 30% IBOA and 2 phr IRGACURE 184, an elongation of 550, a durometer hardness of 84A, and a tensile strength of 2880 psi

³An aliphatic polyester urethane acrylate available commercially from Rahn USA Corp., Aurora, IL

⁴An ethylene acrylic dipolymer elastomer available commercially from DuPont

⁵Commercially available from Ciba Specialty Chemicals and reported to be a sterically hindered phenolic antioxidant.

⁶Isodecyl acrylate, commercially available from Sartomer Company, Inc., Exton, PA

⁷Commercially available from Cabot Corporation, Billerica, MA, CAB-Co-SIL ® TS-530 treated fumed silica is a high-purity silica that has been treated with hexamethyldisilazane. The treatment replaces many of the surface hydroxyl groups on the fumed silica with trimethylsilyl groups, rendering the silica extremely hydrophobic.

TABLE 1A

Sample No.

Physical Properties
1
2
3
4
5

Shore A
29
43
50
75
95

Tensile, psi
176
364
117
2080
2484

100% Mod., psi
114
177
—
679
—

Elongation, %
127
190
34
191
41

Initial CSR Force, N (S-W)
124
147
—
292
—

CSR, % Force Retained (S-W)
16
21
—
0
—

70 hrs. @ 150° C.

In Sample Nos. 1-5, four different elastomers are evaluated, with Sample Nos. 1 and 2 having the same elastomer—KANEKA RC220C—with (Sample No. 2) and without (Sample No. 1) the rubber toughener, VAMAC DP. The control, Sample No. 1, also does not contain an antioxidant or a reactive diluent, whereas the remaining samples (Nos. 2-5) do.

In the examples, compression strength relaxation (“CSR”) is measured in Newtons, and a Shawbury Wallace (“S-W”) fixture is used when conducting the evaluation in accordance with ASTM D6147-97.

The results captured in Table 1A show that the elastomers of choice for a gasketing application would be those demonstrating flexibility (as measured by modulus and elongation) and possess the highest retain CSR percent force retained.

In Table 2 below, various samples are provided with physical property performance given in Table 2A following thereafter. These samples (Nos. 1, 2, and 6-8) again vary the elastomer and also vary the reactive diluent.

TABLE 2

Constituents
Sample No./Amt (wt %)

Type
Identity
1
2
6
7
8

Elastomer
BOMAR BR-7432
—
—
—
78
78

GHL

KANEKA RC220C
90
70
70
—
—

Rubber
VAMAC DP
—
6.5
6.6
6.5
6.6

Toughener

Antioxidant
IRGANOX 1010
—
0.3
—
0.3
—

Reactive
Isobornyl Acrylate
—
13.2
—
13.2
—

Diluent
SARTOMER SR495¹
—
—
13.4
—
13.4

Silica Filler
CABOSIL TS-530
8
8
8
—
—

Photoinitiator
DAROCUR 4265
2
2
2
2
2

¹Commercially available from Sartomer as a trade designation for caprolactone acrylate.

TABLE 2A

Sample No.

Physical Properties
1
2
6
7
8

Shore A
29
43
28
67
58

Tensile, psi
176
364
163
890
393

100% Mod., psi
114
177
55
489
—

Elongation, %
127
190
239
155
86

Compression Set, % 70 hrs @
27
12
21
97
101

150° C.

Initial CSR Force, N (S-W)
124
147
97
251
—

CSR, % Force Retained (S-W)
16
21
24
0
—

70 hrs. @ 150° C.

The results captured in Table 2A show the desired performance properties of flexibility and CSR percent retained forces can be modified and improved through the use of reactive diluents.

In Table 3 below, various samples are provided with physical property performance given in Table 3A following thereafter. These samples (Nos. 9-13) vary the identity and amount of the reactive diluent and the identity of the photoinitiator and silica filler, while including a rubber toughener in Sample Nos. 9-11, but not in Sample Nos. 12 or 13.

TABLE 3

Constituents
Sample No./Amt (wt %)

Type
Identity
9
10
11
12
13

Elastomer
KANEKA RC220C
70
70
70
71.5
71.5

Rubber
HYCAR VTB¹
6.6
6.6
6.6
—
—

Toughener

Antioxidant
IRGANOX 1010
—
—
—
2.5
2.5

Reactive
Isobornyl Acrylate
13.4
—
6
8
—

Diluent
SARTOMER
—
13.4
7.4
8
8

SR395

SARTOMER
—
—
—
—
8

SR531²

Silica Filler
CABOSIL TS-530
8
—
—
—
—

HDK-2000
—
8
8
8
8

Photoinitiator
DAROCUR 4265
2
2
2
—
—

IRGACURE 819
—
—
—
2
2

¹Commercially available from Noveon or Hanse Chemie, Hycar ® VTBN grades of methacrylate-functional acrylonitrile-butadiene-copolymers are promoted for use to improve the impact resistance and increase the elongation.

²Commercially available from Sartomer as a trade designation for cyclic trimethylolpropane formal acrylate

TABLE 3A

Sample No.

Physical Properties
9
10
11
12
13

Shore A
42
26
28
25
21

Tensile, psi
476
198
163
157
98

100% Mod., psi
215
—
72
60
55

Elongation, %
196
150
181
210
158

Visc., cPs @ 0.5 sec-
—
178300
204020
126500
115100

Visc., cPs @ 5 sec-
—
118100
136000
90550
86900

Compression Set,
27
27
34
34
13

% 70 hrs @ 150° C.

Initial CSR Force, N (S-W)
20
195
196
52
95

CSR,
120
5
6
8
28

% Force Retained (S-W)

70 hrs. @ 150° C.

The results in Table 3A indicate that the silica filler HDK-2000 contributes little to the viscosity while providing physical reinforcement to the sample.

In Table 4 below, various samples are provided with physical property performance given in Table 4A following thereafter. These samples (Nos. 14-17) again vary the reactive diluent, though each includes at least fifteen weight percent of DMAA, while using a combination of two different elastomers from Kaneka.

TABLE 4

Sample No./

Constituents
Amt (wt %)

Type
Identity
14
15
16
17

Elastomer
KANEKA RC220C
42.4
42.4
50
42.9

KANEKA RC100C
21.1
21.1
25
21.6

Rubber
HYCAR VTB
2.5
2.5
2.5
2.5

Toughener

Antioxidant
IRGANOX HP2225 FF
1
1
1
1

Reactive Diluent
DMAA
20
20
15
20

Isobornyl Acrylate
5
5
—
5

SARTOMER PRO6622¹
—
5
—
—

SARTOMER SR395
5
5
—
5

SARTOMER SR531
—
—
1.5
—

2-Ethyl hexyl acrylate
—
—
3
—

Silica Filler
HDK-2000
2
2
—
—

Photoinitiator
IRGACURE 2022²
1
1
—
2

IRGACURE 819
—
—
2
—

¹Commercially available from Sartomer as a trade designation for 3, 3, 5 trimethylcyclohexyl acrylate

²IRGACURE 819 dissolved in DAROCURE 1173

TABLE 4A

Sample No.

Physical Properties
14
15
16
17

Shore A
52
50
31
36

Tensile, psi
397
403
247
403

100% Mod., psi
126
145
74
92

Elongation, %
258
231
249
318

Tear Strength, Die C, lbs.-in.
44.6
50.6
—
41.4

Visc., cPs @ 0.5 sec-
5784
4893
9601
8295

Visc., cPs @ 5 sec-
3317
2916
7511
7504

Cure thru depth, mm
10+
7.7
—
7.2

Compression Set,
11
11
16
26

% 70 hrs @ 150° C.

100 hrs. @ 150° C.
—
—
20.5
—

Initial CSR Force, N (S-W)
102
82
187
68

CSR, % Force Retained (S-W)
42
34
5
6

70 hrs. @ 150° C.

Initial CSR force, N (J-O)
107
—
—
98

CSR, % Force Retained (J-O)
46
—
—
55

70 hrs. @ 150° C.

Initial CSR force, N,
3
—
—
—

Dyneon fixture

Tear Strength is elevated in accordance with ASTM D624 and an additional fixture was used in this evaluation, a Jones-Odom (“J-O”) fixture. The different fixtures used in this example show measurements of the same forces but in different sample sizes and configurations.

The results in Table 4A indicate that the physical properties can be varied as well as related sealing performance while maintaining a low viscosity suitable for injection at low pressures.

In Table 5 below, various samples are provided with physical property performance given in Table 5A following thereafter. These samples (Nos. 1, 2 and 18-20) vary the identity of the rubber toughener, while using two different reactive diluents and maintaining in the elastomer as KANEKA RC220C.

TABLE 5

Constituents
Sample No./Amt (wt %)

Type
Identity
1
2
18
19
20

Elastomer
KANEKA RC220C
90
70
70
70
70

Rubber
VAMAC DP
—
6.5
—
—
—

Toughener
HYPALON 20¹
—
—
6.6
—
—

NEOPRENE AD-10²
—
—
—
6.6
—

NIPOL IR2200L³
—
—
—
—
6.6

Reactive
Isobornyl Acrylate
—
13.2
—
—
—

Diluent
SARTOMER SR395
—
—
13.4
13.4
13.4

Silica Filler
CABOSIL TS-530
8
8
8
8
8

Photoinitiator
DAROCUR 4265
2
2
2
2
2

¹Commercially available from DuPont, and reported to be greater than 96% chloro-sulfonated polyethylene, less than 0.4% carbon tetrachloride and less than 0.04% chloroform and less than 2% talc.

²Commercially available from DuPont, and reported to be greater than 98% 2-chloro-1,3-butadiene polymers and copolymers, less than 1% water and less than 1% talc.

³Commercially available from Zeon, and reported to be greater than 99% polyisoprene polymer.

TABLE 5A

Sample No.

Physical Properties
1
2
18
19
20

Shore A
29
43
26
29
27

Tensile, psi
176
364
178
175
81

100% Mod., psi
114
177
62
69
55

Elongation, %
127
190
210
205
123

Compression Set,
27
12
29
27
Not

% 70 hrs. @ 150° C.

Miscible

Initial CSR Force, N (S-W)
124
147
20
20
—

CSR, % Force Retained (S-W)
16
21
15
10
—

70 hrs. @ 150° C.

The results in Table 5A indicate that the physical properties can be varied as well as related sealing performance while maintaining a low viscosity suitable for injection at low pressures by using various rubber toughening agents that are miscible in the composition.

In Table 6 below, various samples are provided with physical property performance given in Table 6A following thereafter. These samples (Nos. 10, 21-23 and 24) again vary the rubber toughener, while again using two different reactive diluents and silica fillers.

TABLE 6

Constituents
Sample No./Amt (wt %)

Type
Identity
21
22
23
10
24

Elastomer
KANEKA RC220C
70
70
70
70
70

Rubber
RICACRYL 3100¹
6.6
—
—
—
—

Toughener
VAMAC DP
—
—
6.6
—
—

HYCAR VTB
—
6.6
—
6.6
6.6

Reactive
Isobornyl Acrylate
13.4
13.4
—
—
13.4

Diluent
SARTOMER
—
—
13.4
13.4
—

SR395

Silica Filler
CABOSIL TS-530
8
8
—
—
—

HDK-2000
—
—
8
8
8

Photoinitiator
DAROCUR 4265
2
2
2
2
2

¹According to the manufacturer, Sartomer, RICACRYL ® 3100 is a methacrylated polybutadiene low-functional UV-curable resin.

TABLE 6A

Sample No.

Physical Properties
21
22
23
10
24

Shore A
34
42
20
26
42

Tensile, psi
504
476
130
198
476

100% Mod., psi
197
215
47
—
215

Elongation, %
209
196
219
150
196

Visc., cPs @ 0.5 sec-
—
—
188500
178300
—

Visc., cPs @ 5 sec-
—
—
113260
118100
—

Compression Set, % 70
43
27
21
27
27

hrs. @ 150° C.

Initial CSR Force, N (S-W)
115
20
136
159
20

CSR, % Force Retained (S-W)
2
120
18
5
120

70 hrs. @ 150° C.

In Table 7 below, various samples are provided with physical property performance given in Table 7A following thereafter. These samples (Nos. 11 and 25-26) vary the amount of elastomer and rubber toughener, while maintaining the remaining components constant in terms of identity and amount.

TABLE 7

Sample No./

Constituents
Amt (wt %)

Type
Identity
11
25
26

Elastomer
KANEKA RC220C
70
74.1
71.6

Rubber Toughener
HYCAR VTB
6.6
2.5
5

Reactive Diluent
Isobornyl Acrylate
6
6
6

SARTOMER SR395
7.4
7.4
7.4

Silica Filler
HDK-2000
8
8
8

Photoinitiator
IRGACURE 819
2
2
2

TABLE 7A

Sample No.

Physical Properties
11
25
26

Shore A
26
26
26

Tensile, psi
163
156
180

100% Mod., psi
72
82
94

Elongation, %
181
169
163

Tear Strength, Die C, lbs.-in.
—
18.3
17.4

Visc., cPs @ 0.5 sec-
204020
172800
191200

Visc., cPs @ 5 sec-
136000
126900
145200

Compression Set, % 70 hrs. @ 150° C.
34
22
38

Initial CSR Force, N (S-W)
196
170
178

CSR, % Force Retained (S-W)
6
19
11

70 hrs. @ 150° C.

In Table 8 below, various samples are provided with physical property performance given in Table 8A following thereafter. These samples (Nos. 1, 6, 8, 23, 27 and 28) vary the amount of KANEKA RC220C elastomer and the identity of reactive diluent and silica filler.

TABLE 8

Constituents
Sample No./Amt (wt %)

Type
Identity
1
27
8
28
6
23

Elastomer
KANEKA RC220C
90
70
78
78
70
70

Rubber Toughener
VAMAC DP
—
6.6
6.6
6.6
6.6
6.6

Reactive Diluent
SARTOMER SR395
—
—
—
13.4
13.4
13.4

SARTOMER SR495
—
13.4
13.4
—
—
—

Silica Filler
CABOSIL TS-530
8
8
—
—
8
—

HDK-2000
—
—
—
—
—
8

Photoinitiator
DAROCUR 4265
2
2
2
2
2
2

TABLE 8A

Sample No.

Physical Properties
1
27
8
28
6
23

Shore A
29
26
58
21
28
20

Tensile, psi
176
160
393
134
163
130

100% Mod., psi
114
107
—
40
55
47

Elongation, %
127
137
86
405
239
219

Visc., cPs @ 0.5 sec-
—
—
—
—
—
188500

Visc., cPs @ 5 sec-
—
—
—
—
—
113260

Compression Set, % 70 hrs. @ 150° C.
27
77
101
21
21
21

Initial CSR Force, N (S-W)
124
—
—
128
97
136

CSR, % Force Retained (S-W) 70 hrs. @
16
—
—
24
24
18

150° C.

In Table 9 below, various samples are provided with physical property performance given in Table 9A following thereafter. These samples (Nos. 1, 2, 6, and 29) vary the amount of the KANEKA RC220C elastomer and the manner by which the rubber toughener is included in the sample.

TABLE 9

Sample No./

Constituents
Amt (wt %)

Type
Identity
1
2
29
6

Elastomer
KANEKA RC220C
90
70
68
70

Rubber Toughener
32.5 parts VAMAC
—
—
20
—

DP dispersed

in Isobornyl

Acrylate

VAMAC DP
—
6.5
—
6.6

Reactive Diluent
Isobornyl Acrylate
—
13.2
—
—

Antioxidant
IRGANOX 1010
—
0.3
2
—

Silica Filler
CABOSIL TS-530
8
8
8
8

Photoinitiator
DAROCUR 4265
2
2
2
2

TABLE 9A

Sample

Physical Properties
1
2
29
6

Shore A
29
43
40
28

Tensile, psi
176
364
363
163

100% Mod., psi
114
177
160
55

Elongation, %
127
190
208
239

Compression Set, % 70 hrs. @ 150° C.
27
12
—
21

Initial CSR Force, N (S-W)
124
147
—
97

CSR, % Force Retained (S-W)
16
21
—
24

In Table 10 below, various samples are provided with physical property performance given in Table 10A following thereafter. These samples (Nos. 23 and 27) vary the identity of the silica filler and the manner by which the rubber toughener is introduced into the sample, with the impact on performance illustrated in Table 10A below.

TABLE 10

Sample

No./Amt

Constituents
(wt %)

Type
Identity
27
23

Elastomer
KANEKA RC220C
70
70

Rubber Toughener
32.5 parts VAMAC DP dispersed
20
—

in Isobornyl Acrylate

VAMAC DP
—
6.6

Reactive Diluent
SARTOMER SR395
—
13.4

Silica Filler
CABOSIL TS-530
8
—

HDK-2000
—
8

Photoinitiator
DAROCUR 4265
2
2

TABLE 10A

Sample

Physical Properties
27
23

Shore A
26
20

Tensile, psi
160
130

100% Mod., psi
107
47

Elongation, %
137
219

Visc., cPs @ 0.5 sec-
—
188500

Visc., cPs @ 5 sec-
—
113260

Compression Set, % 70 hrs. @ 150° C.
77
21

Initial CSR Force, N (S-W)
—
136

CSR, % Force Retained (S-W)
—
18%

In Table 11 below, like Table 4, various samples are provided with physical property performance given in Table 11A following thereafter. These samples (Nos. 13, 16 and 39) again vary the type and amount of reactive diluent, with and without fifteen weight percent of DMAA, while using a combination of two different elastomers from Kaneka.

TABLE 11

Sample No./

Constituents
Amt (wt %)

Type
Identity
13
16
39

Elastomer
KANEKA RC220C
71.5
50
47.5

KANEKA RC100C
—
25
22

Rubber Toughener
NOVEON VTB
2.5
2.5
2.5

Antioxidant
IRGANOX HP2225 FF
—
1
1

Reactive Diluent
DMAA
—
15
15

Isobornyl Acrylate
—
—
5

SARTOMER SR395
8
—
—

SARTOMER SR531
8
1.5
—

2-Ethyl Hexyl Acrylate
—
3
—

Acrylic Acid
—
—
5

Silica Filler
HDK-2000
8
—
—

Photoinitiator
IRGACURE 2022
—
—
2

IRGACURE 819
2
2
—

TABLE 11A

Sample No.

Physical Properties
13
16
39

Shore A
21
31
62

Tensile, psi
98
247
965

100% Mod., psi
55
74
384

Elongation, %
158
249
199

Visc., cPs @ 0.5 sec-
115100
9601
9240

Visc., cPs @ 5 sec-
86900
7511
6361

Cure thru depth, mm
—
—
0.226

Compression Set, % 70 hrs @ 150° C.
13
16
65

Initial CSR Force, N (S-W)
95
187
100

70 hrs. @ 150° C.
28
5
0

In Table 12 below, various samples are provided with physical property performance given in Table 12A following thereafter. These samples (Nos. 14, 17 and 41-42) again vary the type and amount of reactive diluent, with and without fifteen weight percent of DMAA, while using a combination of two different elastomers from Kaneka (apart from Sample No. 42).

TABLE 12

Sample No./

Constituents
Amt (wt %)

Type
Identity
17
41
14
42

Elastomer
KANEKA RC220C
42.9
49.8
42.4
—

KANEKA RC200C
—
—
—
63.5

KANEKA RC100C
21.6
25
21.1
—

Rubber Toughener
NOVEON VTB
2.5
2.5
2.5
2.5

Antioxidant
IRGANOX HP2225
1
1
1
1

FF

Reactive Diluent
DMAA
20
4
20
20

Isobornyl Acrylate
5
3.5
5
5

SARTOMER SR395
5
3.5
5
5

Acrylic Acid
—
0.7
—
—

Silica Filler
HDK-2000
—
8
2
2

Photoinitiator
IRGACURE 2022
2
2
1
1

TABLE 12A

Sample No.

Physical Properties
17
41
14
42

Shore A
36
29
52
—

Tensile, psi
403
259
397
566

100% Mod., psi
92
74
126
100

Elongation, %
318
249
258
295

Tear Strength, Die C, lbs.-in.
41.4
22.8
44.6
—

Visc., cPs @ 0.5 sec-
8295
299300
5784
—

Visc., cPs @ 5 sec-
7504
198100
3317
—

Cure thru depth, mm
7.2
6.1
10
—

Compression Set, % 70 hrs. @
26
13
11
—

150° C.

Initial CSR Force, N (S-W)
68
83
102
—

70 hrs. @ 150° C.
6
28
42
—

Initial CSR force, N(J-O)
98
167
107
182

CSR, % Force Retained (J-O)
55
46
46
67

Initial force, N Dyneon
—
—
3
3

% retained 24 hrs 150° C.
—
—
—
95.7

% retained 70 hrs 150° C.
—
—
—
43.5

In Table 13 below, various samples are provided with physical property performance given in Table 13A following thereafter. These samples (Nos. 15 and 43-45) again vary the type and amount of reactive diluent, with and without rubber toughener and varying the amount of DMAA from between fifteen weight percent to 20 weight percent, while using a combination of two different elastomers from Kaneka (apart from Sample No. 44).

TABLE 13

Sample No./

Constituents
Amt (wt %)

Type
Identity
15
43
44
45

Elastomer
KANEKA RC220C
42.4
47
—
—

KANEKA RC210C
—
—
68
45.3

KANEKA RC200C
—
—
—
22.7

KANEKA RC100C
21.1
18
—
—

Rubber Toughener
NOVEON VTB
2.5
—
—
—

Antioxidant
IRGANOX HP2225 FF
1
1
1
1

Reactive Diluent
DMAA
20
20
15
15

SARTOMER PRO6622
5
—
—
—

SARTOMER SR395
5
—
—
—

Silica Filler
HDK-2000
2
10
15
15

Photoinitiator
IRGACURE 2022
1
4
1
1

TABLE 13A

Sample No.

Physical Properties
15
43
44
45

Shore A
50
60
60
74

Tensile, psi
403
662
626
944

100% Mod., psi
145
274
441
487

Elongation, %
231
232
125
172

Tear Strength, Die C, lbs.-in.
50.6
—
—
—

Visc., cPs @ 0.5 sec-
4893
—
272200
579010

Visc., cPs @ 5 sec-
2916
—
68700
116250

Cure thru depth, mm
7.7
—
—
—

Compression Set, % 70 hrs. @
11
—
13
—

150° C.

Initial CSR Force, N (S-W)
82
—
—
—

70 hrs. @ 150° C.
34
—
—
—

Initial force, N Dyneon
—
—
91
—

% retained 24 hrs 150° C.
—
—
49
—

% retained 70 hrs 150° C.
—
—
44.1
—

Depending on the environment in which the engine gasket seal is to be used, the physical property performance of the composition may vary.

Nevertheless, prior to accelerated ageing, the cured properties in certain applications should be according to the following:

Durometer, Shore A¹
85 +/− 5
50 +/− 5
60 +/− 5
50-70

Tensile Strength, Mpa, min²
8.3
9.0
9.0
7.5

Elongation, %, min³
75
250
180
175

100% Modulus, Mpa, min⁴
3.4
3.0
3.0
2.5

¹ASTM D2240

²ASTM D412C

³ASTM D412C

⁴ASTM D412C

And the compression set after 70 hours at 150° C. should be

Compression Set - 70 hrs. @ 150° C., % max
60
25
25
40

	Number	Date	Country
Parent	11814590	Jul 2007	US
Child	12850768		US

INJECTION MOLDING PROCESS, APPARATUS AND MATERIAL FOR FORMING CURED-IN-PLACE GASKETS

Information

Publication Number

Date Filed

Date Published

Inventors

Original Assignees

CPC

US Classifications

International Classifications

Abstract

Description

Claims

CROSS REFERENCE TO RELATED APPLICATIONS

Provisional Applications (1)

Continuation in Parts (1)