Patent Publication Number: US-2022227067-A1

Title: Apparatus and method for applying multi-component adhesives using jetting valves

Description:
FIELD OF TECHNOLOGY 
     The present application relates to a method and apparatus for applying multi-component adhesives. 
     BACKGROUND 
     Multi-component adhesives combine two or more individual adhesive components that are not adhesive by nature on their own, but which can be mixed to chemically react and form an adhesive. Commonly, on production lines, dispensing implements such as dynamic mix nozzles or static mix nozzles are used to mix and deliver multi-component adhesives onto substrates that are to be adhered together. However, mixing the individual adhesive components and causing them to chemically react before they are delivered onto a substrate presents a number of problems. 
     For instance, multi-component adhesives have a limited pot life, which is the amount time available after formation of the adhesive (i.e., mixing/reacting individual adhesive components) for applying the adhesive while still providing proper bond strength. Accordingly, the amount of time an already mixed multi-component adhesive is in a dispensing implement such as dynamic mix nozzles or static mix nozzles may negatively affect the bond strength of the adhesive. Further, because the chemical reaction of the individual adhesive components occurs inside a dispensing implement such as a dynamic mix nozzles or static mix nozzles, the dispensing implement must be thoroughly cleaned or disposed of after dispensation of the adhesive is complete. The cleaning of dispensing implements or the use of disposable dispensing implements may add significant costs to a manufacturing operation. 
     SUMMARY 
     In one embodiment, a method for depositing a multi-component adhesive on a substrate comprises dispensing a first reactive adhesive component on a first substrate; dispensing a second reactive adhesive component on the first substrate; wherein the first reactive adhesive component and the second reactive adhesive component are dispensed separately; wherein the first reactive adhesive component and the second reactive adhesive component do not mix or chemically react with each other until deposited on the first substrate; and wherein the first reactive adhesive component is dispensed by a first jet valve and the second reactive adhesive component is dispensed by a second jet valve. 
     In some embodiments of the above method for depositing a multi-component adhesive on a substrate, the first reactive adhesive component and the second reactive adhesive component are dispensed as micro-volume deposits. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the first reactive adhesive component and the second reactive adhesive component are dispensed simultaneously. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the first reactive adhesive component and the second reactive adhesive component are dispensed sequentially. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the deposits of the second reactive adhesive component are dispensed to at least partially penetrate the deposits of the first reactive adhesive component. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the first reactive adhesive component and the second reactive adhesive component are dispensed in volumetric ratio of 1:1 or 2:1 through 10:1. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, a first layer of the first reactive adhesive component is deposited on the first substrate and a second layer of the second reactive adhesive component is deposited on the first layer of the first reactive adhesive component 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the deposits of the first reactive adhesive component and the deposits of the second reactive adhesive component are dispensed on the first substrate in an alternating pattern. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the deposits of the first reactive adhesive component and the deposits of the second reactive adhesive component differ in at least one of size, shape, or volume. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the deposits of the first reactive adhesive component and the deposits of the second reactive adhesive component have a volume of approximately 0.0005 ml to 0.01 ml. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the deposits of the first reactive adhesive component and the deposits of the second reactive adhesive component have a volume of approximately 0.001 ml to 0.002 ml. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the striking angle of the first jet valve on the first substrate and the striking angle of the second jet valve on the first substrate are not the same. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the first reactive adhesive component and the second reactive adhesive component are dispensed by non-touch-transfer onto the first substrate. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, each of the first and second jet valves is separated from the first substrate by a separation distance. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the separation distance for each of the first and second jet valves is approximately between 0.05 inches to 0.5 inches. 
     In some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate, the separation distance for each of the first and second jet valves is approximately between 0.25 inches to 0.5 inches. 
     Some embodiments of any of the above methods for depositing a multi-component adhesive on a substrate may further comprise providing a second substrate in relation to the first substrate so that the first reactive adhesive component and the second reactive adhesive component are between the first substrate and the second substrate; applying a force to move the first substrate and the second substrate together, such that the deposit of the first reactive adhesive component and the deposit of the second reactive adhesive component at least partially penetrate each other; and mixing the first reactive adhesive component and the second reactive adhesive component by vibrating the deposit of the first reactive adhesive component and the deposit of the second reactive adhesive. 
     In one embodiment, an apparatus for dispensing a multi-component adhesive comprises a first holding vessel for holding a first reactive adhesive component; a second holding vessel for holding a second reactive adhesive component; a first jet valve connected to the first holding vessel to dispense the first reactive adhesive component; and a second jet valve connected to the second holding vessel to dispense the second reactive adhesive component; wherein first and second holding vessels hold the first and second reactive adhesive components separately and the first and second jet valves dispense the first and second adhesive components separately, such that the first reactive adhesive component and the second reactive adhesive component do not mix or chemically react with each other until after dispensed from the apparatus. 
     In some embodiments of the above apparatus, the first and second jet valves are configured to dispense the first and second reactive adhesive components as micro-volume deposits. 
     In some embodiments of the above apparatus, the first and second jet valves are configured to dispense the first and second reactive adhesive components simultaneously. 
     In some embodiments of the above apparatus, the first and second jet valves are configured to dispense the first and second reactive adhesive components sequentially. 
     In some embodiments of the above apparatus, the first and second jet valves are configured to dispense the first and second reactive adhesive components such that the deposit of the second reactive adhesive component at least partially penetrates the deposit of the first reactive adhesive component. 
     In some embodiments of the above apparatus, the first and second jet valves are configured to dispense the first and second reactive adhesive components in a volumetric ratio of 1:1 or 2:1. 
     In some embodiments of the above apparatus, the first jet valve is configured to deposit a first layer of the first reactive adhesive component on the substrate; and the second jet valve is configured to deposit a second layer of the second reactive adhesive component on the first layer of the first reactive adhesive component. 
     In some embodiments of the above apparatus, the first and second jet valves are configured to dispense the deposit of the first reactive adhesive component and the deposit of the second reactive adhesive component on the substrate in an alternating pattern. 
     In some embodiments of the above apparatus, the first and second jet valves are configured to dispense the first reactive adhesive component and the second reactive adhesive component such that the deposit of the first reactive adhesive component and the deposit of the second reactive adhesive component differ in at least one of size, shape, or volume. 
     In some embodiments of the above apparatus, the first and second jet valves are configured to dispense the first reactive adhesive component and the second reactive adhesive component as deposits having a volume of approximately 0.0005 ml to 0.01 ml. 
     In some embodiments of any of the above apparatuses, the deposits of the first and second reactive adhesive components have a volume of approximately 0.001 ml to 0.002 ml. 
     In some embodiments of the above apparatus, the striking angle of the first jet valve on the substrate and the striking angle of the second jet valve on the substrate are not the same. 
     In some embodiments of the above apparatus, each of the first and second jet valves is separated from the substrate by a separation distance. 
     In some embodiments of the above apparatus, the separation distance for each of the first and second jet valves is approximately between 0.05 inches to 0.5 inches. 
     In some embodiments of the above apparatus, the first and second jet valves are configured to dispense the first and second reactive adhesive components by non-touch-transfer onto the substrate. 
     In some embodiments of any of the above apparatuses, the first and second jet valves are configured to dispense the first and second reactive adhesive components by non-touch-transfer onto a substrate. 
     In some embodiments, the above apparatuses further comprise a control unit for controlling the first and second jet valves in accordance with a defined operational parameter selected from the group consisting of dispensing volume, dispensing velocity, separation distance, striking angle, deposition speed and deposition pattern. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of the exemplary embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the apparatuses and methods of the present application, exemplary embodiments are shown in the Figures; it being understood, however, that the present application is not limited to the specific embodiments disclosed. In the drawings: 
         FIGS. 1 and 2  are schematic drawings of an exemplary apparatus; 
         FIGS. 3-9  show exemplary deposition patterns of reactive components on a substrate; 
         FIG. 10  is a schematic drawing of two substrates bonded by a multi-component adhesive; and 
         FIG. 11  is a flow chart of an exemplary method. 
     
    
    
     DETAILED DESCRIPTION 
     Before the various embodiments are described in further detail, it is to be understood that the present application is not limited to the particular embodiments described. It is also to be understood that the terminology used is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the claims of the present application. 
     Provided is an apparatus  10  for dispensing a multi-component adhesive  12 . The multi-component adhesive  12  is a combination of two or more individual reactive adhesive components  14 , which are not adhesive by nature on their own, but which can be mixed to chemically react and form an adhesive. The individual reactive adhesive components  14  may be provided in combination with one or more non-reactive components and may be provided as fluids that can be delivered under pressure via jet dispending valves. The apparatus  10  holds and dispenses the individual reactive adhesive components  14  separately, such that the individual reactive adhesive components  14  do not mix before they are dispensed by the apparatus  10 . 
     Referring to  FIGS. 1 and 2 , in one embodiment, the apparatus  10  may include a plurality of holding vessels  16  and a plurality of jet valves  18 . Each of the holding vessels  16  contains only one of the individual reactive adhesive components  14 , such that the individual reactive adhesive components  14  are held separately and are not mixed. Further, each of the jet valves  18  may dispense only one of the individual reactive adhesive components  14  so that the individual reactive adhesive components  14  are not mixed in the jet valves  18 . For example, each of the jet valves  18  may be fluidly connected to one of the holding vessels  16  holding only one of the individual reactive adhesive components  14 . The holding vessels  16  may be pressurized, for example, by air pressure, such that the individual reactive adhesive components  14  may be dispensed by the jet valves  18  under pressure. Although the holding vessel  16  and jet valve  18  corresponding to an individual reactive adhesive component  14  are shown as separate components, it will be apparent to those skilled in the art the holding vessel  16  and jet valve  18  corresponding to an individual reactive adhesive component  14  may be integrated into a single component. For example, the jet valve  18  may comprise the holding vessel  16  integrally formed therewith. 
     The jet valves  18  may dispense the individual reactive adhesive components  14  in micro-volume deposits (e.g., dots, beads or lines), such that when the individual reactive adhesive components  14  are dispensed onto a substrate  20 , the individual reactive adhesive components  14  properly mix and react to form the multi-component adhesive  12 . The jet valves  18  preferably dispense the individual reactive adhesive components  14  onto the substrate  20  using non-touch transfers, which allow the individual reactive adhesive components  14  to be deposited on the substrate  20  while maintaining the jet valves  18  at a distance from the substrate  20 . Non-touch transfer allows faster deposition speeds, because it avoids having to place micro-volumes of the individual reactive adhesive components  14  on the substrate  20  while maintaining contact with the dispensing nozzle  22 . 
     The jet valves  18  may be controlled to dispense the individual reactive adhesive components  14  in accordance with various defined operational parameters  24 , including dispensing volume  41 , dispensing velocity  42 , separation distance  43 , striking angle  44 , deposition speed  45  and deposition pattern  46 . The operation of the jet valves  18  and control of the various operational parameters  24  may be implemented using a computer control unit  30 . The computer control unit  30  may have one or more computers, servers and/or devices featuring the necessary electronics, software, memory, storage, databases, firmware, logic/state machines, microprocessors, communication links, displays or other visual or audio user interfaces, printing devices, and any other input/output interfaces to provide any of the functions or services described herein and/or achieve the results described herein. The data and/or computer executable instructions, programs, firmware, software and the like (also referred to herein as “computer executable” components) for controlling the operation of the jet valves  18  and the various operational parameters  24 , may be stored on a computer-readable medium that is within or accessible by the computer control unit  30 , which when executed by a processor (such as a central processing unit, or CPU) of the computer control unit  30 , cause the processor to perform all or a portion of the functions, services and/or methods described herein. 
     The dispensing volume  41  refers to the volume of the individual deposit of reactive adhesive component  14  (e.g., dot, bead or line) dispensed from the jet valve  18 . The jet valves  18  are preferably controlled to dispense the individual reactive adhesive components  14  in micro-volume deposits (e.g., dots, beads or lines) to approximate mixing the reactive adhesive components  14  at the molecular level. By approximating mixing the reactive adhesive components  14  at the molecular level, chemical reaction of the reactive adhesive components  14  is improved, and thus bond strength of the multi-component adhesive  12  is also improved. For example, the jet valves  18  may be controlled to dispense the reactive adhesive components  14  in micro-volume deposits in the range of about 0.0005 ml to 0.01 mi, or more specifically in the range of about 0.001 ml to 0.002 ml. 
     Also, the jet valves  18  may be controlled to dispense the different individual reactive adhesive components  14  at different dispensing volumes  41  in order to accommodate different volumetric mixing ratios required by different multi-component adhesives  12 . For example, for a multi-component adhesive  12  requiring a volumetric mixing ratio of 2:1 of a first individual reactive adhesive component  14   a  to a second individual reactive adhesive component  14   b,  a first jet valve  18   a  may be controlled to dispense the first individual reactive adhesive component  14   a  at a dispensing volume of 0.002 ml and a second jet valve  18   b  may be controlled to dispense the second individual reactive adhesive component  14   b  at a dispensing volume of 0.001 ml. Thus, if an equal number of micro-volume deposits (e.g., dots, beads or lines) of the first and second reactive adhesive components  14   a,    14   b  are deposited on the substrate  20 , then the appropriate 2:1 volumetric mixing ratio may be achieved. 
     The dispensing velocity  42  refers to the velocity of the reactive adhesive component  14  exiting the nozzle  22  of the jet valve  18 . Each jet valve  18  may be controlled to dispense a reactive adhesive component  14  at a desired dispensing velocity  42  in order to control the collision energy of the reactive adhesive component  14  dispensed onto the substrate  20 . Also, each jet valve  18  may be controlled to dispense the reactive adhesive component  14  at a desired dispensing velocity  42  in order to control the shape of the micro-volume deposits (e.g., dots, beads or lines) deposited on the substrate  20 . Thus, each jet valve  18  may be controlled to control the collision energies and shapes of the reactive adhesive components  14  on the substrate  20  in order to promote the mixing and chemical reaction of the individual reactive adhesive components  14 . 
     The separation distance  43  refers to the distance of the nozzle  22  of the jet valve  18  from the substrate  20 . In order to perform non-touch transfers of the reactive adhesive components  14  onto the substrate  20 , each jet valve  18  is maintained at a defined separation distance  43  from the substrate  20 . For example, in some embodiments, the separation distance  43  may be in the range of 0.05 inches to 0.5 inches, or more specifically in the range of about 0.25 inches to 0.5 inches. 
     The striking angle  44  refers to the angle of a nozzle axis  26  of a jet valve  18  with respect to the substrate  20 . Each jet valve  18  comprises a nozzle axis  26  along which reactive adhesive component  14  is expelled from the nozzle  22  of the jet valve  18 . The striking angle  44  is the angle formed by the intersection of the nozzle axis  26  and the surface of the substrate  20 . Each jet valve  18  may be controlled to dispense a reactive adhesive components  14  at a desired striking angle  44  in order to control the shape of the micro-volume deposits (e.g., dots, beads or lines) deposited on the substrate  20 . The flatter the striking angle  44  of the jet valve  18 , the more elongated the shape of the bead becomes; and the steeper the striking angle  44  of the jet valve  18 , the more circular the shape the bead becomes. Thus, the jet valves  18  may be controlled to control the shapes of the reactive adhesive components  14  on the substrate  20  in order to promote the mixing and chemical reaction of the individual reactive adhesive components  14 . 
     The deposition speed  45  refers to the frequency with which each jet valve  18  deposits the dots, beads or lines of a reactive adhesive component  14 . In other words, the deposition speed  45  may be defined as the number of deposits of reactive adhesive component  14  per unit of time. Depending on the pot life of a multi-compound adhesive  12 , it may be important to deposit the reactive adhesive components  14  on the substrate at a certain deposition speed  45  in order to avoid negatively affecting the bond strength of the multi-compound adhesive  12  that is deposited an mixed on the substrate  20 . 
     The deposition pattern  46  refers to the manner in which the individual reactive adhesive compounds  14  are deposited with respect to one another on the substrate  20 . In order to promote the mixing and chemical reaction of the individual reactive adhesive components  14  on the substrate  20 , the individual reactive adhesive components  14  may be deposited on the substrate in various suitable patterns  46 . For example, in some embodiments, the individual reactive adhesive components  14  may be deposited on the substrate  20  as micro-volume deposits (e.g., dots, beads or lines) in alternating patterns in order to ensure proper mixing and chemical reaction. 
     For example, as shown in the embodiments of  FIGS. 3-5 , the individual reactive adhesive components  14  may be deposited on the substrate  20  by the jet valves  18  in alternating layers  28 . The exemplary embodiments of  FIGS. 3-5  are described with reference to a two-component adhesive  12  comprising a first reactive adhesive component  14   a  and a second reactive adhesive component  14   b.  As shown in  FIGS. 3-5 , a layer  28   a  of the first reactive adhesive component  14   a  may be deposited on the substrate  20  and a layer  28   b  of the second reactive adhesive component  14   b  may be deposited on top of the layer  28   a  of the first reactive adhesive component  14   a.    
     As shown in  FIG. 3 , there is one layer  28   a  of the first reactive adhesive component  14   a  and one layer  28   b  of the second reactive adhesive component  14   b,  so that there is a 1:1 volumetric mixing ratio of the first reactive adhesive component  14   a  to the second reactive adhesive component  14   b.  As shown in  FIG. 4 , there is one layer of the second reactive adhesive component  14   b  sandwiched between two layers of the first reactive adhesive component  14   a , so that there is a 2:1 volumetric mixing ratio of the first reactive adhesive component  14   a  to the second reactive adhesive component  14   b.  Thus, as shown, the pattern of layers  28  of the reactive adhesive components  14  may be varied to establish different desired volumetric mixing ratios of the reactive adhesive components  14 . 
     As shown in  FIGS. 3-5 , the layer of the first reactive adhesive component  14   a  and the layer of the second reactive adhesive component  14   b  may be deposited by the jet valves  18  as a series of micro-volume deposits (e.g., dots, beads or lines).  FIG. 5 , shows a layer  28   a  of beads of the first reactive adhesive component  14   a  deposited on the substrate  20  and a layer  28   b  of beads of the second reactive adhesive component  14   b  deposited on top of the layer  28   a  of the first reactive adhesive component  14   a . The deposition of the beads of the second reactive adhesive component  14   b  on top of the beads of the first reactive adhesive component  14   a  promotes mixing and chemical reaction. In particular, various parameters  24 , including dispensing velocity  42  and striking angle  44 , may be controlled to cause the beads of the second reactive adhesive component  14   b  to at least partially penetrate the beads of the first reactive adhesive component  14   a.    
     Further, as shown in  FIG. 5 , the dispensing volumes  41  of the reactive adhesive components  14  may be varied to establish different desired volumetric mixing ratios of the reactive adhesive components  14 . More particularly,  FIG. 5  shows that the beads of the second reactive adhesive component  14   b  have half the dispensing volume  41  of the beads of the first reactive adhesive component  14   a,  so that there is a 2:1 volumetric mixing ratio of the first reactive adhesive component  14   a  to the second reactive adhesive component  14   b.    
     As shown in  FIGS. 6-9 , the individual reactive adhesive components  14  may alternatively be deposited on the substrate  20  by the jet valves  18  in one or more layers  28  comprising an alternating pattern of beads of a first reactive adhesive component  14   a  and beads of a second reactive adhesive component  14   b.  The exemplary embodiments of  FIGS. 6-9  are described with reference to a two-component adhesive  12  comprising a first reactive adhesive component  14   a  and a second reactive adhesive component  14   b.  The deposition of the beads of the first reactive adhesive component  14   a  adjacent to the beads of the second reactive adhesive component  14   b  promotes mixing and chemical reaction. In particular, various parameters  24 , including dispensing velocity  42  and striking angle  44 , may be controlled to cause the beads of the first reactive adhesive component  14   a  and the beads of the second reactive adhesive component  14   b  to at least partially penetrate each other. Further, the beads of the first reactive adhesive component  14   a  and the beads of the second reactive adhesive component  14   b  may be dispense simultaneously or sequentially. 
     In one embodiment, as shown in  FIGS. 6 and 7 , a layer  28  comprising beads of the first reactive adhesive component  14   a  and beads of the second reactive adhesive component  14   b  is deposited on the substrate  20 . The layer  28  comprises lines  32  comprising a series of alternating beads of the first reactive adhesive component  14   a  and beads of the second reactive adhesive component  14   b.  Accordingly, as shown, the beads of the first reactive adhesive component  14   a  are deposited adjacently to the beads of the second reactive adhesive component  14   b.  As shown in  FIG. 7 , the dispensing volumes  41  of the reactive adhesive components  14  may be varied to establish different desired volumetric mixing ratios of the reactive adhesive components  14 . More particularly,  FIG. 7  shows that the beads of the second reactive adhesive component  14   b  have half the dispensing volume  41  of the beads of the first reactive adhesive component  14   a,  so that there is a 2:1 volumetric mixing ratio of the first reactive adhesive component  14   a  to the second reactive adhesive component  14   b.    
     In another embodiment, as shown in  FIGS. 8 and 9 , the layer  28  comprises one set of lines  32   a  comprising a series of beads of the first reactive adhesive component  14   a  and another set of lines  32   b  comprising beads of the second reactive adhesive component  14   b.  As shown, the lines  32   a  of beads of the first reactive adhesive component  14   a  are deposited adjacently and alternatingly with the lines  32   b  of beads of the second reactive adhesive component  14   b.  As shown in  FIG. 9 , the dispensing volumes  41  of the reactive adhesive components  14  may be varied to establish different desired volumetric mixing ratios of the reactive adhesive components  14 . More particularly,  FIG. 9  shows that the beads of the second reactive adhesive component  14   b  have half the dispensing volume  41  of the beads of the first reactive adhesive component  14   a,  so that there is a 2:1 volumetric mixing ratio of the first reactive adhesive component  14   a  to the second reactive adhesive component  14   b.    
     In some embodiments, mixing and chemical reaction of the individual reactive adhesive components  14  may be promoted by optimizing the collision energy associated with dispensing the individual reactive adhesive components  14  onto the substrate  20 . As discussed above, certain parameters  24 , including dispensing volume  41 , dispensing velocity  42  and striking angle  44 , may be varied to control the collision energy to cause the beads of the first reactive adhesive component  14   a  and the beads of the second reactive adhesive component  14   b  to at least partially penetrate each other. In some embodiments, the dispensing velocity  42  may be a max-min-splash velocity. The max-min-splash velocity is the velocity that creates the highest collision energy while not exceeding a specified acceptable level of splash of the reactive adhesive components  14  when dispensed by the jet valves  18  onto the substrate  20 . 
     In accordance with another aspect of the present application, mixing and chemical reaction of the individual reactive adhesive components  14  may be further promoted after deposition on the substrate  20 . Referring to the embodiment of  FIG. 10 , mixing of the reactive adhesive components  14  may be achieved by depositing the multi-component adhesive  12  between a first substrate  20   a  and a second substrate  20   b,  and applying a force to move the first substrate  20   a  and the second substrate  20   b  together, such that the beads of the first reactive adhesive component  14   a  and the beads of the second reactive adhesive component  14   b  at least partially penetrate each other. Still referring to  FIG. 10 , in some embodiments, mixing of the reactive adhesive components  14  may be achieved by vibrating the beads of the first reactive adhesive component  14   a  and the beads of the second reactive adhesive component  14   b,  which can be achieved by vibrating the first substrate  20   a  and/or the second substrate  20   b . In some embodiments, vibration may be achieved by ultrasonic means, mechanical means or other suitable means. 
     In accordance with another aspect of the present application, provided is a method  50  implementing the apparatus  10  for dispensing a multi-component adhesive  12  and bonding two substrates together. The method  50  includes steps for depositing a first reactive adhesive component  14   a  and a second reactive adhesive component on a first substrate  20   a  so that the first and second reactive components  14   a,    14   b  mix and chemically react to form a multi-component adhesive  12 , which can be used to bond the first substrate  20   a  to a second substrate  20   b.    
     As shown in the exemplary embodiment of  FIG. 11 , the method  50  may comprise steps  51 ,  52  of providing a first reactive adhesive component  14   a  in a first holding vessel  16   a  and separately providing a second reactive adhesive component  14   b  in a second holding vessel  16   b . The first and second reactive adhesive components  14   a,    14   b  may be provided in the apparatus  10  described above. The apparatus  10  holds the individual reactive adhesive components  14   a ,  14   b  separately, such that the individual reactive adhesive components  14   a,    14   b  do not mix before they are dispensed by the apparatus  10 . The apparatus  10  comprises separate holding vessels  16   a,    16   b,  where each of the holding vessels  16   a,    16   b  contains only one of the individual reactive adhesive components  14   a ,  14   b,  such that the individual reactive adhesive components  14   a,    14   b  are held separately and are not mixed. 
     The method  50  may further comprise steps  53 ,  54  of dispensing the first reactive adhesive component  14   a  with a first jet valve  18   a  of the apparatus  10  and separately dispensing the second reactive adhesive component  14   b  with a second jet valve  18   b  of the apparatus  10 . The apparatus  10  dispenses the individual reactive adhesive components  14  separately, such that the individual reactive adhesive components  14  do not mix before they are dispensed by the apparatus  10 . Accordingly, each of the jet valves  18  may dispense only one of the individual reactive adhesive components  14  so that the individual reactive adhesive components  14  are not mixed in the jet valves  18 . Further, the jet valves  18  preferably dispense the individual reactive adhesive components  14  onto the substrate  20  using non-touch transfers, which allow the individual reactive adhesive components  14  to be deposited on the substrate  20  while maintaining the jet valves  18  at a distance from the substrate  20 . Additionally, as discussed above, the jet valves  18  may be controlled to dispense the individual reactive adhesive components  14  in accordance with various defined operational parameters  24 , including dispensing volume  41 , dispensing velocity  42 , separation distance  43 , striking angle  44 , deposition speed  45  and deposition pattern  46 . 
     The method  50  may additionally comprise a step  55  of mixing and chemically reacting the individual reactive adhesive components  14  on the substrate  20 . As discussed above, the jet valves  18  may be controlled to dispense the individual reactive adhesive components  14  in accordance with various defined operational parameters  24  that promote mixing and chemical reaction of the individual reactive adhesive components  14  on the substrate. For example, in order to promote the mixing and chemical reaction of the individual reactive adhesive components  14 , the jet valves  18  may be controlled to control the collision energies, shapes and deposition patterns of the reactive adhesive components  14  on the substrate  20 . 
     The method  50  may optionally comprise a step  56  of vibrating the individual reactive adhesive components  14  on the substrate  20  in order to promote the mixing and chemical reaction of the individual reactive adhesive components  14 . Vibration may be achieved by ultrasonic means, mechanical means or other suitable means. 
     The method  50  may comprise a step  57  of bonding a second substrate to the first substrate with the mixed and chemically reacted individual reactive adhesive components  14 . 
     Holding and dispensing the individual reactive adhesive components  14  separately, obviates the need to clean or dispose of the holding vessels  16  and jet valves  18 . Preventing the mixing and chemical reaction of the individual reactive adhesive components  14  of the multi-component adhesive  12  before they are dispensed, preserves the pot life of the multi-component adhesive  12  and thus the bond strength of the multi-component adhesive  12 . Non-touch transfer allows faster deposition speeds, because it avoids having to place micro volumes of the individual reactive adhesive components  14  on the substrate  20  while maintaining contact with the dispensing nozzle  22 . By dispensing the individual reactive adhesive components  14  in micro-volume deposits (e.g., dots, beads or lines) and approximating mixing the reactive adhesive components  14  at the molecular level, chemical reaction of the reactive adhesive components  14  is improved, and thus bond strength of the multi-component adhesive  12  is also improved. 
     Although the apparatuses and methods of the present application have been shown and described with respect to detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and the scope of the present application. With respect to the embodiments of the apparatuses described herein, it will be understood by those skilled in the art that one or more components may be added, omitted or modified without departing from the spirit and the scope of the present application. With respect to the embodiments of the methods described herein, it will be understood by those skilled in the art that one or more steps may be omitted, modified or performed in a different order and that additional steps may be added without departing from the spirit and the scope of the present application.