Patent Publication Number: US-2006012062-A1

Title: Method and apparatus for metering and controlling dispense rate

Description:
BACKGROUND INFORMATION  
      The present invention relates to a method and apparatus for metering and controlling the dispense rate of an in-mold coating (IMC) composition into a mold cavity and onto a molded article or substrate formed from a resin within the mold cavity. The present invention finds particular application as a feedback and control device on a metering cylinder of a dispense and control apparatus that is connected to an injection molding machine.  
      Molded thermoplastic and the thermoset articles, such as those made from polyolefins, polycarbonates, polyesters, polyethylenes, polypropylenes, polystyrenes and polyurethanes, are utilized in numerous applications including those for the automotive, marine, recreation, construction, office products, and outdoor equipment industries. Oftentimes, it is desirable to apply a surface coating to a molded thermoplastic or thermoset article. For example, the molded articles may be used as one part in multi-part assemblies. To “match” the finish of the other parts in such assemblies, the molded articles may require application of a surface coating that has the same finish properties as the other parts. Coatings may also be used to improve surface properties of the molded article such as uniformity of appearance, gloss, scratch resistance, chemical resistance, weatherability, and the like. In addition, surface coatings may be used to facilitate adhesion between the molded article and a separate finish coat to be later applied to the molded article.  
      Numerous techniques have been developed to apply surface coatings to molded plastic articles. Many of these techniques involve the application of a surface coating to plastic articles after they are removed from their molds. These techniques are often multi-step processes involving surface preparation followed by spray-coating the prepared surface with paint or other finishes. In contrast, IMC provides a means of applying a surface coating to molded plastics prior to ejection from the mold. IMC can eliminate the separate manufacturing process of applying a coating to the article upon ejection from the mold thereby reducing the overall cost of manufacturing the article.  
      Molds used with thermoplastics usually are of a “clam shell”-like design having mated halves that meet at a parting line. One of the mated halves typically remains stationary whereas the other half of the mold is typically movable between a closed position and an open, retracted position. To form a molded article, the movable half is moved to its closed position and held closed under a clamping force thereby forming a contained molding cavity. Molten thermoplastic material is injected into the molding cavity. The molded article is formed by thoroughly filling the cavity with the thermoplastic material and allowing the material to sufficiently cool and solidify. During the entire molding process, the movable mold half is maintained in its closed position. After molding, the mold halves can be opened and a finished, molded article can be ejected therefrom.  
      Owing to differences in mold design and molding conditions, processes wherein the mold is cracked or parted prior to injection of an IMC composition are generally not used for the IMC of injection molded thermoplastics. When molding thermoplastics, it is generally necessary to maintain pressure on the movable mold half to keep the cavity closed and prevent material from escaping along the parting line. Further, it is often necessary to “pack” or maintain pressure on the thermoplastic article during molding which also necessitates keeping the cavity closed. Packing the mold helps to provide a more uniform crystalline or molecular structure in the molded article. Without packing, the physical properties of the molded thermoplastic article tend to be impaired.  
      Because injection molding of thermoplastics does not permit the mold to be parted or cracked prior to injection of the IMC into the mold cavity, the IMC composition must be injected under sufficient pressure to compress the thermoplastic article in all areas that are to be coated. By compressing the thermoplastic article, the IMC composition is able to interpose between molding surfaces of the mold cavity and outer surfaces of the molded thermoplastic article. The process of in-mold coating an injection molded thermoplastic article with a liquid IMC is described in commonly owned, copending U.S. Pat. No. 6,617,033 entitled “Method For In-Mold Coating a Polyolefin Article” issued on Sep. 9, 2003; and U.S. patent application Ser. Nos. 09/974,644 entitled “Optimization of In-Mold Coating Injection Molded Thermoplastic Substrate” filed on Oct. 9, 2001; and 10/045,481 entitled “Selectively Controlling In-Mold Coating Flow” filed on Oct. 22, 2001.  
      The method and apparatus used to physically inject the liquid IMC composition into the molding cavity is described in commonly owned, copending U.S. patent application Ser. No. 60/422,784 entitled “Dispense and Control Apparatus And Method For In-Mold Coating An Injection Molded Thermoplastic Article”. The dispense and control apparatus discloses a delivery system for injecting an IMC composition into the cavity of a pair of mold halves on an injection molding machine and a means for controlling the delivery system. However, when injecting IMC composition into the molding, it may be desirable to be able to precisely and variably control the amount and the rate at which the IMC composition is injected over the entire period that IMC composition is injected into the molding cavity.  
      Variably controlling the dispense rate of in-mold coating composition during each injection of the IMC composition into the mold cavity would enable the dispense rate to be adjusted to better correspond to changing conditions within the mold cavity. For example, at the beginning of the IMC injection, a higher dispense rate may be needed to deform the molded substrate and to interpose the IMC composition between the molded substrate and the surface or surfaces of the mold halves. After deformation, a relatively lower dispense rate may be needed to avoid leakage of the injected IMC composition through the mold parting line. At or near the end of the injection of IMC, a relatively higher rate of dispense may be needed to fully coat the molded part because the part is becoming cooler and the coating must be forced into the remote areas or regions of the molded part. Additionally, it is desirable to more precisely control the dispense rate of IMC composition to better correlate the dispense rate with the conditions occurring in the mold cavity.  
     SUMMARY OF THE INVENTION  
      The present method for metering and controlling the dispense rate of an IMC composition into a mold cavity and onto a thermoplastic molded article contained therein that overcomes the foregoing difficulties and others and provides the aforementioned and other advantageous features. The method involves injecting a heated thermoplastic material into the mold cavity, allowing the thermoplastic material to form a thermoplastic article in the mold cavity, and injecting an IMC composition into the mold cavity ( 16 ) and onto the thermoplastic article. Both the amount of and rate that the coating composition is injected into said mold cavity are controlled. The method for metering and controlling can include the use of a linear transducer and programmed logic controller for metering the amount of and rate that the IMC composition is dispensed. Additionally, the method can involve dispensing a first amount of an IMC composition at a first rate, dispensing a second amount of IMC composition at a second rate that is less than the first rate, and, optionally, dispensing a third amount of IMC composition at a third rate that is greater than the second rate.  
      In another aspect of the present invention, an apparatus is provided for controlling the amount and rate of an IMC composition injected into a molding cavity and onto a thermoplastic molded article formed therein. More particularly, in accordance with this aspect of the invention, at least two mold members define a mold cavity. A first composition injector is fluidly connected to the mold cavity for injecting a first composition into the mold cavity. A second composition injector is fluidly connected to the mold cavity for injecting the IMC composition into the mold cavity. The second injector includes a metering cylinder fluidly connected to the molding cavity and holding the IMC composition. A hydraulically driven piston extends into the metering cylinder for evacuating an amount of the IMC composition held therein upon movement in a first direction of the piston. A means for controlling the amount of the IMC composition evacuated by the piston from the metering cylinder is provided. A means for controlling the rate that the piston evacuates the IMC composition from the metering cylinder is also provided.  
      Advantageously, the dispense rate of an IMC composition into a mold cavity can be variably controlled over time. Further, this control can be very precise.  
      Additionally, the maximum IMC composition injection pressure can be regulated by controlling the injection rate. Pressure feedback can be obtained by measuring the dispense amount and rate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a side view of one embodiment of a molding apparatus suitable for use in or with a preferred embodiment of the present invention.  
       FIG. 2  is a partial cross-section through a vertical elevation of a mold cavity.  
       FIG. 3  is a perspective view of an in-mold coating dispense and control apparatus adapted to be connected to the molding apparatus of  FIG. 1  according to a preferred embodiment of the present invention.  
       FIG. 4  is a cross-sectional view of a metering cylinder assembly of the dispense and control apparatus of  FIG. 3  wherein the metering cylinder assembly includes a linear transducer.  
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS  
      Referring now to the drawings wherein the showings are for purposes of illustrating a preferred embodiment of the invention only and not for purposes of limiting the same and like reference numerals are used to indicate like or corresponding parts throughout the several figures,  FIG. 1  shows a molding apparatus or injection molding machine  10  according to a preferred embodiment of the present invention. Molding apparatus  10  includes a first mold half  12  and a second mold half  14 . First mold half  12  preferably remains in a stationary or fixed position. In  FIG. 1 , movable mold half  14  is shown in an open position. Movable mold half  14  is movable to a closed position wherein the first and second mold halves mate with one another to form a contained mold cavity  16  therebetween (See  FIG. 2 ). More specifically, mold halves  12 ,  14  mate along surfaces  18  and  20  ( FIG. 1 ) when movable mold half  14  is in the closed position, forming a parting line  22  ( FIG. 2 ) therebetween and around mold cavity  16 .  
      Moveable mold half  14  reciprocates generally along a horizontal axis relative to first or fixed mold half  12  by action of a clamping mechanism  24  with a clamp actuator  26  such as through a hydraulic, pneumatic or mechanical actuator as known in the art. The clamping pressure exerted by clamping mechanism  24  should have an operating pressure in excess of the pressures generated or exerted by either one of a first composition injector  30  and a second composition injector  32 . In the preferred embodiment, the pressure exerted by clamping mechanism  24  ranges generally from about 13.8 to about 103.3 MPa (i.e., 2,000 to about 15,000 pounds per square inch (psi)), preferably from about 27.6 to about 82.7 MPa (4000 to 12,000 psi), and more preferably from about 41.3 to about 68.9 MPa (6000 to 10,000 psi) on the mold surface.  
      With additional reference to  FIG. 2 , mold halves  12 ,  14  are shown in a closed position abutting or mating with one another along parting line  22  to form mold cavity  16 . It should be readily understood by those skilled in the art that the design of mold cavity  16  can vary greatly in size and shape according to the desired end product or article to be molded. Mold cavity  16  generally has a first surface  34  on second mold half  14 , upon which a show surface of an article will be formed, and a corresponding or opposite second surface  36  on first mold half  12 . First mold half  12  defines a first orifice  38  connecting to mold cavity  16  that allows first composition injector  30  to inject its composition into mold cavity  16 . Similarly, second mold half  14  defines a second orifice  40 , also connecting to mold cavity  16  that allows second composition injector  32  to inject its composition into mold cavity  16 .  
      First composition injector  30  is that of a typical injection molding apparatus which is well known to those of ordinary skill in the art. More specifically, first composition injector  30  is generally capable of injecting a thermoplastic composition, generally a resin or polymer, into mold cavity  16 . Owing to space constraints, first injector  30  used to inject the thermoplastic composition is positioned to inject material from fixed half  12  of the mold. It is to be understood that first composition injector  30  could be reversed and placed in movable mold half  14 . Second composition injector  32  is generally capable of injecting an IMC composition into mold cavity  16  to coat the molded article formed therein. In the illustrated embodiment, second injector  32  is shown positioned in movable mold half  14 . However, it is to be understood that second injector  32  could be alternatively positioned in stationary mold half  12 .  
      First composition injector  30  is shown in a “backed off” position, but it is readily understood that the same can be moved in a horizontal direction so that a nozzle or resin outlet  42  of first composition injector  30  mates with mold half  12 . In the mated position, first composition injector  30  is capable of injecting its contents into mold cavity  16 . For purposes of illustration only, first composition injector  30  is shown as a reciprocating-screw machine wherein a first composition can be placed in a hopper  44  and a rotating screw  46  can then move the composition through a heated extruder barrel  48 , where the first composition or material is heated above its melting point. As the heated material collects near the end of barrel  48 , rotating screw  46  acts as an injection ram and forces the material through nozzle  42  and into mold cavity  16 . Nozzle  42  generally has a valve (not shown) at the open end thereof and rotating screw  46  generally has a non-return valve (not shown) to prevent the backflow of material into rotating screw  46 .  
      First composition injector  30  is not meant to be limited to the embodiment shown in  FIG. 1  but can be any apparatus capable of injecting a thermoplastic composition into mold cavity  16 . For example, the injection molding machine can have a mold half movable in a vertical direction such as in a “stack-mold” with center injection. Other suitable injection molding machines include many of those available from Cincinnati-Milacron, Inc. (Cincinnati, Ohio); Battenfeld Injection Molding Technology (Meinlerzhagen, Germany); Engel Machinery Inc. (York, Pa.); Husky Injection Molding Systems Ltd. (Bolton, Canada); BOY Machines Inc. (Exton, Pa.) and others.  
      With reference to  FIG. 3 , an IMC dispense and control apparatus  60  is capable of being connected to molding apparatus  10  for providing IMC capabilities and controls therefor to molding apparatus  10 . Control apparatus  60  is more fully described in the above-referenced commonly owned, copending &#39;784 application. Generally, control apparatus  60  includes a receiving cylinder  62  for holding an IMC container filled with an IMC composition. A suitable IMC composition is disclosed in commonly owned, U.S. Pat. No. 5,777,053 entitled “In-Mold Coating Compositions Suitable As Is For An End Use Application”. Control apparatus  60  further includes a metering cylinder or tube  64  and an air-driven transfer pump  66 . Metering cylinder  64  is selectively and fluidly connectable to the coating container in receiving cylinder  62 . More specifically, a fluid line (not shown) connects the coating container to metering cylinder  64 . A valve (not shown) is provided on the fluid line for controlling communication therethrough. Transfer pump  66  is adapted to selectively pump the IMC composition of the coating container to metering cylinder  64  when the valve is in an open position.  
      Using conventional fluid communication lines (not shown), metering cylinder  64  is fluidly connectable to second injector  32  of molding apparatus  10 . A hydraulic means such as a hydraulically driven piston is provided for selectively evacuating IMC composition held in metering cylinder  64  therefrom as will be described in more detail below. The evacuated IMC composition is directed by and through the fluid communication lines to second injector  32 . Control apparatus  60  includes appropriate connections (not shown) for connecting control apparatus  60  to a conventional electric power source and a conventional compressed air source. Specifically, control apparatus  60  includes an electric box  74  that is capable of being connected to a conventional 460 volt AC or DC power outlet. Electric box  74  includes a plurality of controls  76  and a touch pad controller  78  thereon for controlling the dispensing of the IMC coating composition from control apparatus  60  to molding cavity  16  of molding apparatus  10  as will be described in more detail below. The electric power source provides power for the electronics, electronic controls and hydraulic pump of control apparatus  60 . The compressed air source provides power for transfer pump  66 .  
      With reference to  FIG. 4 , a metering cylinder assembly  100  is shown including metering cylinder  64  and the hydraulic means for evacuating or forcing the contents, such an amount of an IMC composition, held or contained within metering cylinder  64  therefrom. Specifically, the hydraulic means includes a hydraulic cylinder  102  and a hydraulically actuated piston  104  selectively driven by hydraulic cylinder  102 . Piston  104  is connected to a rod or shaft assembly  106  that extends into metering cylinder  64 . Hydraulic cylinder  102  can be electronically-controlled as is well-known in the art and powered by the dispense and control apparatus  60 . Alternatively, a pneumatic cylinder or mechanical gear driven cylinder could be used in place of the hydraulic means.  
      Shaft assembly  106  is movable between a retracted position and an extended position. In the retracted position, shaft assembly  106  is retracted toward one end of metering cylinder  64  and allows an amount or volume of an in-mold coating composition to be provided to metering cylinder  64  and held therein. In the fully extended position, shaft assembly  106  is extended into metering cylinder  64  toward the other end thereof. Moving from the retracted position to the extended position, shaft assembly  106  expunges or evacuates an amount of an IMC composition contained within metering cylinder  64  therefrom. When evacuated, the expunged amount of IMC composition is directed through a conduit or evacuation fluid line  108  which directs the removed amount of the IMC composition toward second injector  32 . It should be noted that the fluid communication lines of control apparatus  60  are generally filled with a static load of IMC composition.  
      In accordance with the present invention, a linear transducer  110  is provided for measuring linear travel, including the position, movement and/or speed, of shaft assembly  106  relative to a fixed point on metering cylinder  64 . Linear transducer  110  can be a conventional linear transducer such as a TEMPOSONIC™ R series sensor (MTS Systems Corp.; Cary, N.C.). Specifically, linear transducer  110  includes a sensor tube or rod  112  and a circular magnet or toroidal member  114  annularly disposed about rod  112 . The toroidal member  114  is connected to shaft assembly  106  such that toroidal member  114  moves with shaft assembly  106 . Rod  112  generally extends in the same direction as the movement of piston assembly  106  and is held in a fixed position relative thereto. Alternatively, rod  112  could be connected to shaft assembly  106  and toroidal member  114  could be held in a fixed position. In either arrangement, an electronic pulse or current pulse is created in a head  116  of linear transducer  110  and sent speeding down rod  112 . The current pulse interacts with a magnetic field created by toroidal member  114  thereby producing a strain pulse that travels back up rod  112  to head  116 . The position of toroidal member  114  is determined by the amount of time it takes between launching the electronic pulse and the strain pulse to return. Of course, the position of toroidal member  114  corresponds to the position of shaft assembly  106  within metering cylinder  64 .  
      Based on the determined position of toroidal member  114  on rod  112 , linear transducer  110  produces a voltage reading that is sent to a programmable logic controller or PLC (not shown) that forms part of dispense and control apparatus  60 . Using the PLC, shaft assembly  106  can be controlled by position and/or linear travel between two positions. For example, shaft assembly  106  via piston  104  can be moved to a specified location or position such as its retracted position, its extended position, or any specified position therebetween. Shaft assembly  106  can also be moved via piston  104  from one specified position to another over a predetermined time interval. In other words, the rate of travel or speed of shaft assembly  106  can be controlled. The speed at which the piston  104  and shaft assembly  106  move corresponds to the pressure at which the amount of IMC composition is evacuated from metering cylinder  64 .  
      Using linear transducers and PLCs to control piston movement in hydraulic cylinders is generally well known by those skilled in the art. Additionally, there are several alternative known mechanisms that can be used to precisely and variably control hydraulic cylinder  102  of the present invention. Linear transducer  110  shown and described herein is for illustrative purposes only and is not intended to limit the present invention. All other known means of precisely and variably controlling hydraulic cylinders and/or providing position and travel related feedback are to be considered within the scope of the present invention.  
      To make an IMC thermoplastic article, with reference to  FIG. 1 , a thermoplastic first composition is placed in hopper  44  of molding apparatus  10 . First injector  30  is moved into nesting or mating relation with fixed mold half  12 . Through conventional means, i.e., using heated extruder barrel  48  and rotating screw  46 , first injector  30  heats the first composition above its melting point and directs the heated first composition toward the nozzle  42  of first injector  30 . Mold halves  12 ,  14  are closed thereby creating contained molding cavity  16 .  
      Next, a nozzle valve (not shown) of nozzle  42  is moved to an open position for a predetermined amount of time to allow a corresponding quantity of first composition to enter mold cavity  16 . Rotating screw  46  provides a force or pressure that urges the first composition into mold cavity  16  until the nozzle pin is returned to its closed position. The first composition is filled and packed into mold cavity  16  as is well known in the art. Once mold cavity  16  is filled and packed, the molded first composition is allowed to cool thereby forming a molded thermoplastic article.  
      While the molding process is occurring, the valve controlling fluid communication between the IMC coating container and metering cylinder  64  is moved to its open position to permit fluid communication between the coating container and metering cylinder  64 . Shaft assembly  106  is in its retracted position at this time, i.e. during filling of metering cylinder  64 . Transfer pump  66  then pumps the IMC composition from the coating container to metering cylinder  64 . When metering cylinder  64  is filled to a desired amount, the valve closes to prevent more IMC composition from entering metering cylinder  64 . Next, control apparatus  60  opens a valve or pin (not shown) on second injector  32  to allow fluid communication between second injector  32  and mold cavity  16 . The pin is normally bias or urged toward a closed position but is selectively movable toward the open position by control apparatus  60 . Specifically, an electrically powered hydraulic pump (not shown) of control apparatus  60  is used to move the pin.  
      After the first composition has been injected into mold cavity  16  and the surface of the molded article to be coated has cooled below the melt point or otherwise reached a temperature or modulus sufficient to accept or support an IMC composition but before the surface has cooled too much such that curing of the IMC composition would be inhibited, the hydraulic means is actuated. Specifically, the PLC, using linear transducer  106 , directs hydraulic piston  104  to move from its initial, retracted position to a first specified position whereby shaft assembly  106  extends into the metering cylinder  64  thereby evacuating an amount of IMC composition from metering cylinder  64 . In addition to moving piston  104  and shaft assembly  106  to a specified position, the PLC also controls the rate at which hydraulic position  104  moves to the first specified position. Generally, the rate will correspond to a pressure at which the IMC composition is evacuated from metering cylinder  64  and injected into mold cavity  16  by second injector  32 . The rate at which piston  104  travels to its first specified position and the corresponding pressure of that rate may be such to deform the substrate and interpose the IMC composition between the thermoplastic molded article and the walls of one or both of mold halves  12 ,  14 .  
      Next, piston  104  and shaft assembly  106  can be moved from the first specified position to a second specified position at a different, typically decreased, rate of travel. The new rate may correspond to a pressure that is low enough to avoid leakage of the IMC composition through parting line  22 . Finally, piston  104  and shaft assembly  106  can be moved from the second specified position to a third specified position or the extended position of piston  104 . The rate of speed piston  104  and shaft assembly  106  travel in route to the third specified position is again adjustable and may correspond to a rate and pressure sufficient to fully coat the molded thermoplastic article with the IMC composition. The rate of speed of this third movement may need to be higher than the second movement because the molded thermoplastic article may be cooler and the IMC composition may need to be forced into remote locations on the molded part.  
      Although the IMC process has been described with reference to three movements used to evacuate the IMC composition from metering cylinder  64  and fully coat the part, it should be understood that any number of movements are possible and a varying or same rate of speed may be used on each movement. All combinations of movements and speeds are to be considered within the scope of the present invention.  
      As each movement of piston  104  and shaft assembly  106  evacuates the IMC contained in metering cylinder  64  and delivers the IMC to second injector  32 , the IMC composition is injected through the nozzle (not shown) and into mold cavity  16 . The IMC composition spreads out from the mold surface and coats a predetermined portion or area of the molded article. Immediately or very shortly after the IMC composition is fully injected into mold cavity  16 , control apparatus  60  allows the valve of second injector  32  to return to its closed position thereby preventing further injection of the IMC composition into mold cavity  16 . It is important to note that the mold is not opened or unclamped before the IMC composition is applied. That is, mold halves  12 ,  14  maintain a parting line  22  and generally remain substantially fixed relative to each other while both the first and second compositions are injected into mold cavity  16 .  
      After the predetermined amount of IMC composition is injected into mold cavity  16  and it covers or coats the predetermined area of the article or substrate, the coated substrate can be removed from the mold. However, before the mold halves  12 ,  14  are parted, the IMC composition is cured by components present within the coating composition. The cure is optionally heat activated, from sources including the substrate or mold halves which are at or above the curing temperature of the IMC composition. Cure temperature will vary depending on the in-mold coating utilized. As mentioned above, it is important to inject the IMC composition before the molded article has cooled to the point below where proper curing of the composition can be achieved. The IMC composition requires a minimum temperature to activate the catalyst present therein which causes a cross-linking reaction to occur, thereby curing and bonding the composition to the substrate.  
      Controls  76  and keypad  78  of control apparatus  60  enable an operator to adjust and/or set certain operating parameters of control apparatus  60 . For example, controls  76  can be manipulated to increase or decrease the amount of IMC composition to be filled in metering cylinder  64  by allowing the valve that controls communication between metering cylinder  64  and receiving container  62  to remain open for a longer duration. Further, controls  76  which communicate with the PLC can be used to set the number of movements made by hydraulic piston  104 , the specified location or locations that piston  104  moves to, i.e., its length of travel, and the rate at which piston  104  moves during each movement. As mentioned above, these rates can be adjusted to provide the IMC composition into mold cavity  16  at optimal pressures that correspond to the molding process and the coating of the molded thermoplastic article.  
      Although the present invention has been illustrated and described as using a linear transducer in conjunction with a PLC, it is contemplated that a variable control valve positioned downstream of metering cylinder  64  could be used to accomplish several of the functions performed by linear transducer  110 . The control valve could be electronically controlled by the PLC as is known in the art to variably and precisely control the pressure at which the in-mold coating composition is delivered to molding cavity  16 . Alternatively, the variable control valve could be used in addition to linear transducer  110  to provide two means for variably and precisely controlling the dispense rate of the in-mold coating composition into mold cavity  16 . Use of a control valve to variably and precisely meter and control the dispense rate of the IMC composition with or without linear transducer  110  is to be considered within the scope of the present invention. It is further contemplated that all disclosed means of variably and precisely controlling the dispense rate of the IMC composition disclosed in the present invention could be used on one or more of the multiple component metering cylinders disclosed in commonly owned, co-pending U.S. patent application Ser. No. 60/422,740 entitled “High Pressure Delivery and Mixing System for Multiple In-Mold Coating Components and Method of Delivering and Mixing Multiple In-Mold Coating Components” filed on Oct. 31, 2002. In the &#39;740 application the positioning of a variable control valve, if included, would preferably be between the mixer and the second injector.