WO2004041518A1

WO2004041518A1 - Method and system for delivering and mixing multiple in-mold coating components

Info

Publication number: WO2004041518A1
Application number: PCT/US2003/033185
Authority: WO
Inventors: Douglas Mcbain; Elliott Straus; John Thompson
Original assignee: Omnova Solutions Inc.
Priority date: 2002-10-31
Filing date: 2003-10-17
Publication date: 2004-05-21
Also published as: AU2003282951A1

Abstract

An in-mold coating delivery and mixing system includes at least two mold member (12, 14) defining a mold cavity (16). A first injector (30) is fluidly connected to said mold cavity (16) for injecting a first composition into said mold cavity (16) to form a molded article. A second injector is fluidly connected to said mold cavity (16) for injecting an in-mold coating composition into said mold cavity (16) to coat the molded article. A mixer is fluidly connected to said second injector) for mixing a plurality of in-mold coating components prior to introduction into said mold cavity (16).

Description

METHOD AND SYSTEM FOR DELIVERING AND MIXING MULTIPLE IN-MOLD COATING COMPONENTS

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a delivery and mixing system and method for delivering and mixing two or more in-mold coating (IMC) components prior to being injected into a molding cavity to coat a molded article or substrate. The delivery and mixing system and method can be used in conjunction with a dispense and control apparatus and an injection molding machine and will be described with particular reference thereto; however, the invention may relate to other similar environments and applications.

[0002] Molded thermoplastic and thermoset articles, such as those made from polyolefins, polycarbonates, polyesters, polystyrenes and polyurethanes, are utilized in numerous applications including those for automotive, marine, recreation, construction, office products, and outdoor equipment industries. Oftentimes, application of a surface coating to a molded thermoplastic or thermoset article is desirable. For example, 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 thereto. [0003] Numerous techniques to apply surface coatings to molded plastic articles have been developed. Many of these involve applying 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 a molded article prior to its ejection from the mold. [0004] Molds used with thermoplastics usually are of a "clam shell" design having mated halves that meet at a parting line. One of the mated halves typically remains stationary whereas the other half typically moves 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 material is injected into the molding cavity. The molded article is formed by thoroughly filling the cavity with the molten 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 ejected therefrom.

[0005] 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, maintaining pressure on the thermoplastic material during molding, which also requires keeping the cavity closed, often is necessary to assist in providing a more uniform crystalline or molecular structure in the molded article. Without such packing (i.e., pressure maintenance), physical properties of the molded thermoplastic article tend to be impaired.

[0006] Because injection molding does not permit the mold to be parted or cracked prior to injection of the IMC composition into the mold cavity, the IMC composition must be injected under sufficient pressure to compress the article in all areas that are to be coated. The compressibility of the molded article dictates how and where the IMC composition covers it. The process of IMC an injection molded article with a liquid IMC composition is described in, for example, U.S. Patent No. 6,617,033 and U.S. Patent Publication Nos. 2002/0039656 A1 and 2003/0082344 A1. [0007] The method and apparatus used to physically inject the liquid IMC composition into the molding cavity of an injection molding machine during the molding of an article, also referred to herein as a dispense and control method and apparatus, is described in commonly owned, co-pending U.S. Patent Application No. 60/422,784 entitled "Dispense and Control Apparatus and Method For In-Mold Coating An Injection Molded Thermoplastic Article" filed on October 31 , 2002. 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. Specifically, the dispense and control apparatus is capable of delivering an IMC composition into the mold cavity at pressures that can reach 35 MPa (about 5000 psi) or higher.

[0008] The dispense and control apparatus described in the 784 application is conFig.d to deliver only a single IMC component from a specified IMC container to the molding cavity of the injection molding machine. However, in some applications, delivering more than a single IMC component into the molding cavity of an injection molding machine may be desirable. Additionally, mixing the IMC components prior to injecting them into the molding cavity and/or matching or varying the ratios of the IMC components relative to one another also may be desirable.

[0009] For example, it may be desirable to mix a basic IMC composition with a color agent component during the IMC process but prior to injection into the mold cavity. Further, it may be desirable to be able to rapidly and conveniently change the specific color agent component between IMC injections which would enable the injection molded article to be molded in a variety of colors. Previously, when IMC compositions were used to impart a desired color or tint, coloring agents such as pigments, dies or the like were added to and blended with the IMC composition before injection. This required large quantities of premixed IMC compositions of various colors to be kept in inventory. The ability to mix a coating composition in-process with a coloring agent would reduce the overall number of different IMC compositions and the total amount of IMC composition required to be kept in inventory when molded parts are required to be coated in a variety of colors. Delivering only a single IMC component would not allow an IMC composition to be mixed in-process with a color agent or allow the mixed coating and color to be together delivered into the molding cavity. Additionally, it would be desirable to meter the amount of the color component or pigment relative to the amount of the IMC composition, thereby allowing the color of the mixed two component composition to be adjusted to varying desired shades or hues. [0010] Another example of when it is desirable to be able to deliver more than a single IMC component is when a specific IMC composition has a relatively short pot-life. An IMC composition is said to have a short pot-life if it rapidly gels and cures after being prepared. This is problematic because gelation and curing may occur prematurely, i.e., prior to injection into the molding cavity. If the IMC composition gels and cures prior to being injected, the fluid lines of the delivery apparatus can become clogged with solidified IMC composition. [0011] To prevent premature gelation and curing of an IMC composition with a short pot-life, a dispense and control apparatus and method that allows an IMC composition to be prepared immediately before or just prior to injection into the molding cavity is desirable. This can be done by keeping separate two or more of the reactive components of the IMC composition until just before the time to inject the IMC composition into the molding cavity. Then, the components can be mixed and together delivered to the molding cavity before significant reaction occurs between the reactive components. [0012] A multiple component delivery and mixing apparatus can allow an IMC composition with a short pot-life to be created immediately prior to being injected into the molding cavity. Such an apparatus would increase the overall number of different IMC compositions available for use and, in particular, allow the use of IMC compositions comprised of relatively more reactive components by minimizing the contact time between the reactive elements prior to use of the IMC composition. Further, because these IMC compositions are created just prior to injection, they are less likely to chemically degenerate to the point that the IMC composition is no longer able to cure to a molded thermoplastic at or below a specific, desired temperature. [0013] Prior art chemical component mixing devices are generally unsuitable for use with the relatively high pressures required for injection of the IMC into the mold cavity. Prior art mixing devices include static or impingement-type mixing heads that direct two or more flow streams into one another under relatively low pressures, such as 0.35 MPa (about 50 psi) to 1.0 MPa (about 150 psi). Turbulent flow conditions created by the colliding flow streams mix the same. Additionally, baffles or fins can be used to further create turbulent flow for enhanced mixing between the components of the flow streams. However, the injection pressure required to inject IMC into the molding cavity can reach 35 MPa (about 5000 psi). Accordingly, there is a need for a high pressure mixing device for use in a delivery and mixing system that is capable of mixing components under pressure where the pressures on the components may reach 35 MPa (about 5000 psi).

SUMMARY OF THE INVENTION

[0014] The present invention provides a system and method for delivering and mixing multiple IMC components. The system includes at least two mold members defining a mold cavity. A first injector is fluidly connected to the mold cavity for injecting a first composition into the mold cavity to form a molded article. A second injector is fluidly connected to the mold cavity for injecting an IMC composition into the mold cavity to coat the molded article. Fluidly connected to the second injector is a mixer for mixing a plurality of components of the coating composition prior to introduction of the coating composition into the mold cavity. The method utilizes this system to in-mold coat a molded article.

[0015] In the foregoing system and method, an amount of a first IMC composition component can be delivered into at least one receiving cylinder, an amount of a second IMC composition component can be delivered into another receiving cylinder, the components can be mixed prior to injection of the IMC composition into the mold cavity. [0016] In another aspect, the present invention provides a device for mixing two or more IMC composition components. The mixing device includes first and second input ports and an outlet port in fluid communication with a mixing chamber. A driven mixer shaft can extend into the mixing chamber for mixing first and second IMC composition components, respectively entering through the first and second input ports, as the components pass through the mixing chamber to the outlet port. [0017] The delivery system and method can deliver multiple IMC composition components to a mold cavity and, if desired, mix those components prior to delivery. This can be done even where at least one of the components is under a relatively high pressure such as up to about 35 MPa or higher.

[0018] Further, the delivery and mixing system and method allow for adjustably matching or varying the ratios of two or more IMC composition components relative to each other. One of the components can be a colorant, pigment, or the like. [0019] Also, this delivery and mixing system is capable of being cleaned between injections of the IMC composition into the mold cavity and/or between mixing and injection operations.

[0020] Further, the delivery and mixing system allows the use of an IMC composition with relatively short pot-life.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Fig. 2 is a partial cross-section through a vertical elevation of a mold cavity. [0023] Fig. 3 is a schematic view of a delivery and mixing system including a mixing device for mixing multiple IMC components and delivering the same to the molding apparatus of Fig. 1 according to a preferred embodiment of the present invention.

[0024] Fig. 4 is a schematic view of a delivery and mixing system according to another preferred embodiment of the present invention.

[0025] Fig. 5 is a perspective view of the mixing device of Fig. 3.

[0026] Fig. 6 is a front elevation view of the mixing device of Fig. 5.

[0027] Fig. 7 is a side elevation view of the mixing device of Fig. 5.

[0028] Fig. 8 is a cross-section view of the mixing device taken along the line A-A of

Fig. 7.

[0029] Fig. 9 is a partial enlarged cross-section view of the mixing device taken along the line A-A of Fig. 7.

[0030] Fig. 10 is another partial enlarged cross-section view of the mixing device taken along the line A-A of Fig. 7.

DETAILED DESCRIPTION OF THE INVENTION

[0031] Referring to the drawings where like reference characters represent like elements and which illustrate certain embodiments of the invention, Fig. 1 shows a molding apparatus or injection molding machine 10 which includes first mold half 12 and second mold half 14. First mold half 12 preferably remains in a stationary or fixed position. Movable mold half 14 is shown in an open position but is movable to a closed position wherein the first and second mold halves 12,14 mate with one another to form contained mold cavity 16 of a finite volume therebetween, as shown in Fig. 2. More specifically, mold halves 12,14 mate along surfaces 18 and 20 (Fig. 1) when mold half 14 is in a closed position, forming parting line 22 (Fig. 2) therebetween and around mold cavity 16.

[0032] Movable mold half 14 reciprocates generally along a horizontal axis relative to mold half 12 by action of clamping mechanism 24 with clamp actuator 26 such as through a hydraulic, pneumatic or mechanical actuator as known in the art. Preferably, the clamping pressure exerted by clamping mechanism 24 should be capable of generating an operating pressure in excess of the pressures generated or exerted by either one of first composition injector 30 and second composition injector 32. For example, pressure exerted by clamping mechanism 24 can range generally from 14 MPa (about 2,000 psi) to about 103 MPa (about 15,000 psi), preferably from about 27 MPa (about 4,000 psi) to about 83 MPa (about 12,000 psi), and more preferably from about 41 MPa (about 6,000 psi) to about 69 MPa (about 10,000 psi) of the mold surface.

[0033] In 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 having a substantially fixed volume. 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 first surface 34 on second mold half 14 and a corresponding or opposite second surface 36 on first mold half 12. First mold half 12 defines 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 second orifice, also connecting to mold cavity 16, that allows second composition injector 32 (Fig. 1) to inject its composition into mold cavity 16.

[0034] First composition injector 30 is that which is typical in an injection molding apparatus or thermosetting and 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 article-forming composition is positioned to inject material from fixed mold half 12, although first composition injector 30 could be reversed and placed in movable mold half 14. Second composition injector 32 is capable of injecting an IMC composition into mold cavity 16 to coat the molded article formed therein, although second composition injector 32 alternatively could be positioned in mold half 12.

[0035] In Fig. 1 , first composition injector 30 is shown in a "backed off' position, but the same can be moved in a horizontal direction so that a nozzle or resin outlet 42 of first injector 30 mates with mold half 12. In the mated position, 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 hopper 44 and rotating screw 46 can move the composition through heated extruder barrel 48, where first composition or material is heated above its melting point. As the heated material collects near the end of barrel 48, 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 screw 46 generally has a non-return valve (not shown) to prevent backflow of material into screw 46.

[0036] 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 flowable (e.g., thermoplastic or thermosetting) 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, Pennsylvania), Husky Injection Molding Systems Ltd. (Bolton, Canada), BOY Machines Inc. (Exton, Pennsylvania) and others.

[0037] With reference to Fig. 3, an IMC delivery and mixing system 60 is shown for mixing multiple IMC components and delivering mixed components to second injector 32 which can then selectively inject mixed components into mold cavity 16. System 60 includes a first receiving cylinder 62 for holding first container of first IMC composition component and a second receiving cylinder 64 for holding second container of second IMC composition component. Once appropriate coating containers are placed in receiving cylinders 62,64, fluid lines 66,68 can be operatively connected to coating containers for transferring the respective coating components through system 60. [0038] For purposes of illustration only, first IMC component could be an IMC composition such as that disclosed in U.S. Patent No. 5,777,053. If combined with a color agent, the IMC composition component preferably is substantially free of any pigment, dye or the like, i.e. contains less than 10% by weight of the pigment or coloring additive and preferably contains no added pigment or coloring additive. The IMC composition component need not be clear or transparent, and the ingredients may make the compositions opaque, hazy, or the like.

[0039] Also, for purposes of illustration only, the second IMC component can be a colorant including at least one pigment and a carrier. The pigment encompasses those materials typically characterized as pigments, dyes, and the like. The pigments are well known in the art and also include phosphorescent, luminescent, fluorescent, metal- escent, and pearlescent materials. Examples of organic and inorganic pigments which can be used in this invention include, but are not limited to iron blue ZnO, TiO₂, chrome yellow, carbon black, chrome orange, chrome green, Zn₂CrO₄, red lead, lethol red, the lakes, azo type toners, phthalocyanines, aluminum hydrates, Fe₂O₃, white lead, extenders, Ti-containing pigments, S-containing pigments, extenders, CaCO₃, AI₂O₃, lithopane, ultraphone, lead chromate, CdS, CdSe, BaSO₄, azo pigments, anthraquinone and vat pigments, phthalocyanine pigments, acrylamino yellow, MgO, chrome red, antimony oxide, ZnS, MgF₂ and ground barites. Metallic pigments can be used, and examples are aluminum flakes and various metal oxides. Mixtures of pigments, dyes, and the like can be used if desired

[0040] The color component pigment is dissolved or dispersed in a carrier so that the colorant is in a liquid or fluid form and capable of being injected onto the molded substrate. Suitable carriers include, for example, liquid epoxy, polyester, or acrylate polymers. Pigment to carrier ratios preferably range be from about 0.01 :1 to about 0.8:1 color pigment for a liquid epoxy carrier, about 0.05:1 to about 0.6:1 for a polyester carrier, and about 0.1 :1 to about 0.5:1 for an acrylate polymer carrier. [0041] Alternatively, the two components could be parts of an IMC composition that, when combined and mixed, form an IMC composition but are kept separate to prevent premature reaction. For example, the IMC composition may include both an initiator and an accelerator that are preferably kept separate from one another until just prior to injection of the composition into mold cavity 16. An IMC composition having an initiator and accelerator is described in commonly-owned, copending U.S. Provisional Patent Application No. 60/402,426 entitled "Method for Coating Molded Thermoplastic Articles". [0042] System 60 further includes a first metering tube or cylinder 70 and a second metering tube or cylinder 72. With fluid lines 66,68 connected to the coating containers, metering cylinders 70,72 are fluidly connected to each of the respective coating components. Fluid line 66 includes first pumping means 74 and first control valve 76. Likewise, fluid line 68 includes second pumping means 78 and second control valve 80. In a preferred embodiment, pumping means 74,78 are air-driven transfer pumps such as those manufactured by DOPAG (Valence, France). Pumps 74,78, also referred to herein as element pumps, are connected to a conventional compressed air source for pumping an amount of each of first and second IMC components from their respective containers to their respective metering cylinders 70,72. Valves 76,80 control communication between respective coating component containers and respective metering cylinders 70,72. [0043] Each metering cylinder 70,72 includes a hydraulic means H for moving a piston 82 which is adapted to evacuate the amount of first and second IMC composition components pumped into metering cylinders 70,72 therefrom. Specifically, pistons 82 are capable of evacuating the IMC composition components at pressures of up to about 35 MPa or more. Upon evacuation by pistons 82, the amount of first IMC composition component is directed through a first evacuation fluid line or conduit 84 and the amount of second IMC composition component is directed through a second evacuation fluid line or conduit 86. Hydraulic means H can be a conventional electrically powered hydraulic pump that operates on a hydraulic fluid to move pistons 82. [0044] Downstream from conduits 84,86, evacuated IMC components are directed to a mixer such as a high-pressure, motor-driven dynamic mixer 90. Control valves 92,94 are provided on conduits 84,86 to control relative proportions or ratios of IMC components entering mixer 90. Mixer 90 functions to mix first IMC composition component with second IMC composition component as will be described in more detail below. [0045] In Fig. 5, mixer 90 includes a first input port 92 fluidly connected to first conduit 84 for receiving first IMC composition component from first metering cylinder 70. Mixer 90 also includes a second input port 94 fluidly connected to second conduit 86 for receiving second IMC composition component from second metering cylinder 72. With reference to Fig. 8, mixer 90 defines mixing chamber 96 fluidly connected to an output port 98 defined in one end of mixer 90. First input port 92 is fluidly connected to mixing chamber 96 by first passageway 100 and second input port 94 is fluidly connected mixing chamber 96 by second passageway 102.

[0046] Mixer 90 includes mixing body 104, marrying block 106, first and second guide blocks 108,110, first and second valve assemblies 112,114 and mixer assembly 116. Mixing body 104 includes output port 98 at a first end thereof and defines a substantial portion of mixing chamber 96 connected to output port 98. The portion of mixing chamber 96 defined by mixing body 104 is open at a second, opposite end of mixing body 104. Marrying block 106 is adjacent the second end of mixing body 104 and closes mixing chamber 96 thereby defining the remaining portion of mixing chamber 96.

[0047] In Fig. 9, marrying block 106 includes first angular throughhole 118, which extends from first upper angled surface 120 of marrying block 106 to first lower angular surface 122 of marrying block 106, and second angular throughhole 124, which extends from second upper angled surface 126 of marrying block 106 to second lower angular surface 128 of marrying block 106. First and second lower angular surfaces 122,128 extend from a lower, flat surface 130 of marrying block 106 and are received within an upper, expanded portion 132 of mixing chamber 96. First vertical surface 134 connects one end of first lower angular surface 122 to flat surface 130. Likewise, second vertical surface 136 connects one end of second lower angular surface 128 to flat surface 130. Vertical surfaces 134,136 and side walls (not shown) extending between angular surfaces 122,28 and vertical surfaces 134,136 mate with interior walls 138 that define upper portion 132. Third throughhole 140 extends from an upper flat surface 142 positioned between first and second upper angular surfaces 120,126 to a portion of flat surface 130 positioned between lower angular surfaces 122,128. Third throughhole 140 is generally aligned and colinear with mixing chamber 96. An O-ring seal 143 or other seal is provided between mixing body 104 and marrying block 106 to seal the mixing chamber and prevent fluid contained within mixing chamber 96 from escaping between mixing body 104 and marrying block 106.

[0048] First guide block 108 is positioned adjacent first upper angled surface 120.

First guide block 108 includes throughhole 144 that is generally aligned and colinear with first angular throughhole 118 of marrying block 106. First guide block 108 also includes first auxiliary port 145 which is in fluid communication with throughhole 144 through narrowing communication passage 146. Passage 146 is oriented perpendicularly relative to throughhole 144.

[0049] Similar to first guide block 108, second guide block 110 is positioned adjacent second upper angled surface 126. Second guide block 1 10 includes throughhole 148 that is generally aligned and colinear with second angular throughhole 124 of marrying block 106. Second guide block 110 also includes second auxiliary port 149 which is in fluid communication with throughhole 148 through narrowing communication passage 150. Passage 150 is oriented perpendicularly relative to throughhole 148.

[0050] In Fig. 8, mixer assembly 116 includes air-driven motor unit 160 having output shaft 162. Motor unit 160 includes conventional connection means (not shown) suitable for controlling and powering the air-driven motor as is well known. Fixedly attached to output shaft 162, a mixer shaft 164 extends through throughhole 140 of marrying block 106 and into the mixing chamber 96. Mixing shaft 164 includes an extension portion 166 and mixing portion 168. An annular seal 170 such as an O-ring or other seal optionally greased with a polymyte or similar material is provided near mixing chamber 96 for preventing the contents of mixing chamber 96 from passing between extension portion 168 of mixing shaft 164 and interior wall 172 defining third throughhole 140. When rotated, mixing shaft 164 is capable of mixing two components delivered through first and second input ports 92,94 as the two components are moved through mixer 90 and out through output port 98. Output port 98 is connected to an injection conduit 174 (Fig. 3) that directs exiting components from mixer 90 to second injector 32 of injection molding machine 10 (Fig. 1). Motor unit 160 is optionally adapted to rotate mixing shaft 164 at selectively variable speeds for adjustably controlling mixing quality obtained by mixer 90.

[0051] In Fig. 10, first valve assembly 112 includes first conventional air cylinder unit

176 and first needle member 178 movable by unit 176 between a first, retracted position and a second, extended position. Adjacent the lower angular surface 122, valve seat member 180 is provided. More specifically, valve seat member 180 includes tubular section 182 matingly received within a lower counterbore of first angular throughhole 118 and adapted to annularly surround distal end 186 of needle member 178. Valve seat member 180 also includes cap section 188 that closes one end of tubular section 182. Cap section 188 includes an outer flange portion 190 having mounting holes 192 therethrough for securing cap section 188 to first guide block 108 using suitable connection means such as screws (not shown). Cap section 188 further includes opening 196 for fluid communication between upper portion 132 of mixing chamber 96 and an interior of tubular section 182. First needle member 178 selectively closes opening 196 and prevents fluid communication therethrough in its extended position and allows fluid communication through opening 196 in its retracted position. Thus, first needle member 178 and valve seat member 180 form a valve for controlling fluid communication between throughhole 118 and mixing chamber 96. [0052] A plurality of seals are provided along first passageway 100 to prevent any component contained therein from escaping desired flow path. More specifically, an O- ring seal 202 or other seal optionally combined with a polymyte or similar material is provided in throughhole 144 adjacent marrying block 106. Bushing 204 is provided in first angular throughhole 118 adjacent first guide block 108. An O-ring seal 206 or other seal is provided between marrying block 106 and first guide block 108 annular spaced about throughholes 118,144. An O-ring seal 208 or other seal is provided at the end of tubular section 182 opposite cap section 188.

[0053] Second valve assembly 114 is similar to first valve assembly 112 and, accordingly, is not shown in detail like first valve assembly 112 in Fig. 10. With reference to Fig. 9, second valve assembly 114 includes second conventional air cylinder unit 210 and second needle member 212 movable by unit 210 between a first, retracted position and a second, extended position. Adjacent the lower angular surface 128, valve seat member 213 includes a tubular section matingly received within a lower counterbore of second angular throughhole 124. Tubular member is adapted to annularly surround a distal end of needle member 212. Valve seat member 213 also includes a cap section that closes one end of the tubular section. Cap section includes an outer flange portion having mounting holes therethrough for securing the cap section to second guide block 110 using a suitable connection means such as screws. Cap section further includes opening 228 for fluid communication between upper portion 132 of mixing chamber 96 and an interior of tubular section. Second needle member 212 selectively closes opening 228 and prevents fluid communication therethrough in its extended position and allows fluid communication through opening 228 in its retracted position. Thus, second needle member 212 and valve seat member 213 form a valve for controlling fluid communication between throughhole 124 and mixing chamber 96. [0054] A plurality of seals are provided along second passageway 102, similar to first passageway 100, to prevent any component contained in second passageway 102 from escaping desired flow path. More specifically, an O-ring seal or other seal optionally combined with a polymyte material is provided in throughhole 148 adjacent marrying block 106. A bushing is provided in second angular throughhole 124 adjacent second guide block 110. Another O-ring seal or other seal is provided between marrying block 106 and second guide block 110 annular spaced about throughholes 124,148. Yet another O-ring seal or other seal is provided at the end of the tubular section opposite the cap section.

[0055] In Fig. 3, second injector 32 is connected to output port 98 (Fig. 8) by injection conduit 174 for receiving the mixed IMC composition as it is forced through mixing device 90. Second injector 32 is selectively fluidly connectable to molding cavity 16 and disposal container 240. More specifically, second injector 32 is fluidly connected to second orifice 40 of molding cavity 16 by fluid passageway 242. Valve 244 is provided on passageway 242 for controlling communication between second injector 32 and molding cavity 16. Second injector 32 is also fluidly connected to disposal container 240 by fluid conduit 246. Valve 248 is provided on fluid conduit 246 for controlling communication between second injector 32 and disposal container 240. [0056] Disposal container 240 serves to collect used cleaning solvent and cleaned residual coating from mixer 90 and injector 32. More specifically, mixer 90 and second injector 32 are capable of being cleaned before and after IMC injections. Cleaning may be desirable to remove IMC residue after an IMC injection. For example, if first IMC composition component is a typical IMC composition and the second IMC component is a colorant, it may be desirable to change the colorant for purposes of applying a coating of another color. In this case, it may be necessary to remove any remaining mixture of the IMC composition and a first colorant prior to mixing and injecting a second colorant with the IMC composition.

[0057] More specifically, with reference to Fig. 5, mixer 90 includes solvent port 250 that is in fluid communication with mixing chamber 96. With reference to Fig. 3, solvent port 250 is fluidly connected to source container 252 of a cleaning solution or solvent by fluid conduit 254. An air-driven pump 256 is positioned on fluid conduit 254 and, when selectively actuated, pump 256 moves fluid from container 252 and into mixing chamber 96 of mixer 90 for removing any residual amounts of mixed IMC components. Valve 258 is provided on fluid conduit 254 between pump 256 and mixer 90 for regulating flow of solvent pumped from container 252 to mixer 90.

[0058] Between valve 258 and mixer 90, conduit 260 connects to fluid conduit 254.

Conduit 260 connects to a compressed air source 261 and is adapted to selectively force air into fluid conduit 254. Valve 262 is provided on conduit 260 to prevent solvent or other undesirable materials from flowing upstream in conduit 260 toward the compressed air source when no air is being forced into conduit 254. By closing valve 258 and opening valve 262, air flow can be used to force solvent from mixer 90. More specifically, with needle members 178,212 extended and preventing fluid communication between mixing chamber 96 and conduits 84,86 and with valve 244 closed and valve 248 open, air flow can be used to force any solvent out of mixing chamber 96, through second injector 32 and into disposal container 240. [0059] To make an IMC article, with reference to Fig. 1 , a first composition is placed in hopper 44 of molding apparatus 10. Prior to injecting the first composition to form the molded article, the movable mold half 14 is closed by clamp mechanism 24 to create contained molding cavity 16 having a substantially fixed volume. In the closed position, clamping mechanism 24 maintains clamping pressure sufficient to maintain mold halves 12,14 in closed relation even when first composition and second composition are injected into mold cavity 16 under pressure. Also prior to injecting first composition, first injector 30 is moved into nesting or mating relation with fixed mold half 12.

[0060] Through conventional means, i.e., using heated extruder barrel 48 and rotating screw 46, first injector 30 heats first composition above its melting point and directs it toward nozzle 42 of first injector 30. If nozzle 42 is equipped with a nozzle valve, it is moved to an open position for a predetermined amount of time and a quantity of first composition is allowed to enter mold cavity 16. Screw 46 provides an injection pressure or force that urges first composition into mold cavity 16, until the nozzle valve is returned to its closed position if a nozzle valve is provided. First composition is filled and packed into mold cavity 16 as known in the art. Once mold cavity 16 is filled and packed, molded first composition is allowed to cool, thereby forming a molded thermoplastic article.

[0061] While the molding process occurs, pumps 74,78 fill metering cylinders 70,72 with a desired amount of respective first and second IMC composition components. Specifically, valves 76,80 are opened to allow pumps 74,78 to fill metering cylinders 70,72 for a desired period of time that corresponds to a desired amount of respective first and second IMC composition components. After metering cylinders 70,72 are filled to their respective desired amounts, valve 244 between mixer 90 and second injector 32 is opened to allow fluid communication between second injector 32 and mold cavity 16. Valve 244 is normally biased or urged toward a closed position but is selectively movable toward the open position. Valves 248,258,262 are generally closed when valve 244 is open.

[0062] After 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 a coating composition of applied thereto, the first and second IMC composition components can be mixed and injected through second orifice 40 into mold cavity 16 and onto the molded article. If the mixed IMC composition is cured by heat, injection of the coating composition before the surface of the molded article has cooled so much that curing of the IMC composition would be inhibited is desirable. In any case, to mix and inject the IMC composition, pistons 82 are actuated and thereby evacuate the respective amounts of first and second coating components from first and second metering cylinders 70,72. First and second coating components are directed through conduits 84,86, through control valves 92,94 and to mixer 90. [0063] Needle members 178,212 are moved and/or held in the open, retracted position to allow the first and second coating components to flow from conduits 84,86, through input parts 92,94 and into mixing chamber 96. Mixer 90 mixes first and second coating composition components together in mixing chamber 96 by rotating mixer shaft 164 as the first and second coating composition components enter and pass through mixing chamber 96. The coating components form a coating composition that is forced out of mixer 90, through conduit 174 and into second injector 32. With valve 244 open to molding cavity 16 and valve 248 closed, the mixed coating composition is forced through the second injector and into mold cavity 16. Control valves 92,94 can be used to match or vary relative proportions of the ratio of first IMC component entering mixer 90 relative to second IMC component entering mixer 90.

[0064] The mold is not opened or undamped before the coating composition is applied. That is, the mold halves maintain a parting line 22 and generally remain substantially fixed relative to each other while both the first (substrate-forming) composition and the second coating composition are injected into mold cavity 16. Thus, the substantially fixed volume of mold cavity 16 is maintained throughout the molding and coating steps. The IMC composition spreads 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, the valve of second injector 32 returns to its closed position thereby preventing further injection of the IMC mixture into mold cavity 16.

[0065] After the predetermined amount of IMC composition is injected into mold cavity 16 and 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 are parted, the IMC composition is cured. The cure is optionally heat activated, from sources including substrate or mold halves 12,14 which are at or above the curing temperature of the IMC composition. Cure temperature will vary depending on the specific IMC composition utilized. As mentioned above, the IMC composition preferably is injected before the molded article has cooled to the point below where proper curing of the coating mixture 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 coating mixture to the substrate. [0066] If desired, prior to a subsequent injection of mixed IMC components, solvent from solvent container 252 can be forced through mixer 90 to remove any residual portions of mixed first and second coating components More specifically, between IMC injections, needle members 178,212 are moved to their extended, closed positions. Valves 244,262 remain closed. Valves 248,258 are opened to allow fluid communication from solvent source 252, through mixing chamber 96 and second injector 32, and to disposal container 240. Solvent passing through mixing chamber 96 and second injector 32 removes residual portions of the IMC components that may remain after an IMC injection. Removal of residual portions may be particularly desirable when it is desired to change the mixed coating type between injections such as, for example, when a change of coating color is desirable, the coating has a relatively short pot-life and/or it is not desirable to risk injecting a coating mixture into mold cavity 16 that may have significantly degenerated. After sufficient solvent has passed through mixer 90 and the second injector, valve 258 can be closed. Thereafter, valve 262 can be opened and forced air from conduit 262 is allowed to pass through mixing chamber 96 and second injector 82. The forced air serves to purge solvent from mixer 90 and second injector 32 and direct the purged solvent to disposal container 240. Upon removal of the solvent, mixer 90 and second injector 32 are ready for a subsequent injection so valves 248,258,262 related to the clean-out function can be closed and needle members 178,212 can be returned to their open positions. [0067] System 60 is controlled as described in the above-referenced 784 application. Although system 60 of the present invention uses two transfer pumps 62,64, two metering cylinders 70,72 and a mixer 90, the dispense and control apparatus and method described in the 784 application are easily adapted to control system 60 of the present invention. Instead of actuating a single transfer pump, both transfer pumps 62,64 are actuated to fill the pair of metering cylinders 70,72 via fluid conduits 66,68. At the desired point in time in the molding process, the hydraulic means is actuated to evacuate the pair of metering cylinders 70,72 simultaneously. Mixer 90 is air driven and easily can be adapted to run off the compressed air source to which the dispense and control apparatus is described as being connected. Likewise, relatively easy modifications to the dispense and control apparatus allow the dispense and control apparatus to adjustably control the control valves 92,94 as desired and clean the mixer 90 using solvent when desired.

[0068] In system 60, use of an IMC composition component and a colorant component allows IMC articles to be color matched or adjusted on a part by part basis during production runs. Generally, to be acceptable for use, molded articles must meet various standards including color requirements. Off color in-mold coated articles can be rejected by a customer. The color of an IMC article can be optimized utilizing the present method.

[0069] As stated herein, a predetermined amount of both the colorant and the IMC composition component can be mixed in the IMC injection apparatus and injected onto the molded substrate, thereby producing a coated article having a defined color. The color of the succeeding article can be adjusted by setting or adjusting the amount of color component metered onto the substrate. Adding greater amounts of a colorant will generally increases the color intensity or strength of the article, whereas decreasing the amount of the colorant tends to mute or dull a coating finish. The setting or adjusting of the coating components amounts can be adjusted manually or otherwise such as through software for injection apparatuses as known in the art. Accordingly, IMC articles can be produced having a desired color, shade, or hue. [0070] In Fig. 4, an IMC delivery and mixing system 310 is shown in accordance with another preferred embodiment of the present invention. System 310 shares many of the same components as system 60 of the first preferred embodiment including receiving containers 62,64, pumps 74,78, and valves 76,80. System 310 differs in that it includes a conventional low-pressure mixer 312 upstream of a single metering cylinder 314. The IMC composition components of first and second containers 62,64 are pumped at a relatively low pressure through mixer 312 to metering cylinder 314. Thus, the mixing of the components occurs as metering cylinder 314 is being filled to a desired amount. The hydraulic means is then used to move a piston 82 to evacuate the mixed components from metering cylinder 314 and direct the mixed components to second injector 32 for injection thereby into mold cavity 16. Valve 316 can be included on the fluid line connecting metering cylinder 314 to second injector 32 for controlling fluid communication therebetween. Another valve 318 can be included on the fluid line connecting mixer 312 to metering cylinder 314 for controlling fluid communication between these components.

[0071] System 310 allows the two components to mix at an earlier stage in the molding process than does system 60. System 60 is well suited for the mixing of IMC composition components to form an IMC composition that has a relatively short pot-life because the mixing of the components occurs at later point in the molding process and closer to the injection of the IMC composition into mold cavity 16. System 310 may be preferably used where IMC composition components are mixed to create an IMC composition where the pot-life of the coating composition will not expire prior to injection of the mixed composition into mold cavity 16. For example, system 310 may be used when an IMC composition with a relatively long pot-life is the first IMC component and a colorant is the second component. System 310 is less complicated as it does not require high pressure mixing.

[0072] In either system 60 or 310, use of an IMC composition component and a colorant component allows IMC articles to be color matched or adjusted on a part-by- part basis during production runs.

[0073] As stated herein, a predetermined amount of both the colorant component and the IMC composition component are mixed in the IMC injection apparatus and injected onto the molded substrate, thereby producing a coated article having a defined color. The color of the succeeding article can be adjusted by setting or adjusting the amount of colorant component metered into the composition. [0074] Although not illustrated in Fig. 4, system 310 may additionally include a solvent source and appropriate lines for directing a solvent through mixer 312 for cleaning purposes as described in reference to system 60 of the first preferred embodiment. Additionally, the solvent may be directed through metering cylinder 312 to clean any residue from the mixed components passing therethrough. In a similar manner, system 60 of the first preferred embodiment may include additional lines for directing the solvent through one or both of first and second metering cylinders 70,72 for cleaning purposes.

[0075] Although systems 60 and 310 are illustrated and described as being adapted to deliver and mix two IMC composition components, each of systems 60 and 310 easily can be modified to be configured to deliver and/or mix three or more components. Such modifications are to be considered within the scope of the present invention.

Claims

CLAIMS We claim:

1. A delivery and mixing system (60) comprising: at least two mold members (12,14) defining a mold cavity (16); a first injector (30) fluidly connected to said mold cavity (16) for injecting a first composition into said mold cavity (16) to form a molded article; and a second injector (32) fluidly connected to said mold cavity (16) for injecting a coating composition into said mold cavity (16) to coat said molded article contained therein, said second injector being fluidly connected to a mixer (90) for mixing a plurality of components of said coating composition prior to said coating composition being introduced into said mold cavity (16).

2. The delivery and mixing system (60) of claim 1 further comprising: a first receiving cylinder (62) holding a first coating component and fluidly connected to said mixer (90); a second receiving cylinder (64) holding a second coating component and fluidly connected to said mixer (90); at least one valve between said receiving cylinder (62) and said mixer (90); and at least another valve between said receiving cylinder (64) and said mixer (90).

3. The delivery and mixing system (60) of claim 2 further comprising: a first metering tube (70) fluidly connected and between said first receiving cylinder (62) and said mixer (90); a second metering tube (72) fluidly connected and between said second receiving cylinder (64) and said mixer (90); a first pumping means (74) between said first metering tube (70) and said first receiving cylinder (62) for pumping said first coating component into said first receiving cylinder (62); a second pumping means (78) between said second metering tube (72) and said second receiving cylinder (64).

4. The delivery and mixing system (60) of claim 3 further comprising a hydraulic means (H) for evacuating said first and second coating components from said first and second metering tubes (70,72) under pressure and directing said first and second coating components toward said mixer (90).

5. The delivery and mixing system (60) of claim 4 wherein said hydraulic means evacuates said first and second coating components under pressure up to 35 MPa and said components are thoroughly mixed by said mixer (90).

6. The delivery and mixing system (60) of any of claims 3 to 5 wherein: said at least one valve is a first control valve (76) that regulates flow of said first coating component between said first receiving cylinder (62) and said first metering tube (70); and said at least another valve is a second control valve (80) that regulates flow of said second coating component between said second receiving cylinder (64) and said second metering tube (72).

7. The delivery and mixing system (60) of any of claims 3 to 5 wherein: said at least one valve is a first regulating valve (92) between said first metering tube (70) and said mixer (90); and said at least another valve is a second regulating valve (94) between said second metering tube (72) and said mixer (90), said valves (92,94) regulating proportions of said first coating component and said second coating component relative to one another.

8. The delivery and mixing system (60) of any of claims 1 to 7 further comprising: a disposal container (240) fluidly connected to said mixer (90); a valve (244) between said mixer (90) and said disposal container (240) for regulating fluid communication therebetween; a solvent source (252) fluidly connected to said mixer (90); a valve (258) between said mixer (90) and said solvent source (252) for regulating fluid communication therebetween; a valve (244) between said mold cavity (16) for preventing fluid communication (a) between said disposal container (240) and said mold cavity (16) and (b) between said solvent source (252) and said mold cavity (16) when said valve (244) is in a closed position; valves (178,180 and 212,213) in said mixer (90) preventing fluid communication between said disposal container (240) and said solvent source (252) when in respective closed positions; and a pump (256) connected to said solvent source (252) for pumping solvent through said mixer (90) and into said disposal container (240) when said valves (244,258) are in respective open positions.

9. The delivery and mixing system (60) of any of claims 1 to 8 wherein said mold cavity (16) has a substantially fixed volume when said mold members (12,14) are closed.

10. The delivery and mixing system (60) of any of claims 2 to 9 wherein said mixer (90) has (i) a mixing chamber (96) that fluidly connects to said cavity (16) and said first and second receiving cylinders (62,64) and (ii) a powered mixing shaft (168) that mixes said first and second coating components as said components pass through said mixing chamber (96).