CURABLE RESIN SYSTEMS

[001] The present invention relates to a two-component mixing and dispensing system, for mixing and dispensing first and second components of a curable resin system, for example for use as an adhesive or filler system, from a cartridge. The present invention also relates to a kit of parts for fitting to a cartridge containing a first (A) and second (B) components of a curable resin system to form a two-component mixing and dispensing system.

[002] It is well known to use curable resin systems is a variety of applications, for example for making fibre-reinforced resin composite materials for the manufacture of structural and decorative components in a variety of industrial sectors. The curable resin system typically comprises at least one monomer of a thermosetting resin and a curing agent. A variety of different curable thermosetting resins are known which require a monomer and a curing agent, such as epoxy resins, vinyl resins, polyester resins, etc. For example, the thermosetting resin may comprise an epoxy resin having one or more epoxide functional groups on the epoxy resin monomer. The epoxy resin may comprise a single epoxy resin monomer or a blend of epoxy resin monomers. The curing agent for the epoxy resin may be selected from curing agents known in the art as being suitable for curing epoxide resins, optionally together with at least one additional curing agent additive or modifier, and/or accelerator. The curing agent is selected to correspond to the epoxy resin used and to achieve the desired cured resin properties using the desired curing conditions. For example, known epoxy resin curing agents may typically be selected from a dicyandiamide, sulphanilamide, urone, urea, imidazole, Fenuron, amine, halogenated boron complex, anhydride, lewis base, phenolic novolac, or a nitrogen containing compound.

[003] Curable resin systems are sold to a customer as a two component system. The first component is the curable resin component (A), and the second component is the curing agent component (B), which may also include an accelerator. The first and second components are required to be homogeneously mixed prior to use to form a homogeneous mixture of the first and second components which is then subsequently shaped/moulded and cured to form a cured thermosetting resin product. It is important that the two components (A + B) are mixed at the correct ratio, and tolerance of this ratio, in order to maintain correct product performance.

[004] It is known to those skilled in the art to provide a single cartridge which comprises the two components of the curable resin system in different compartments of the cartridge. The cartridge is inserted into a cartridge gun, and the compartments are simultaneously compressed by a piston, actuated by a trigger mechanism, to express the two components simultaneously from an outlet of the cartridge. A mixing device in an outlet nozzle is used downstream of the cartridge outlet to mix the components which is then outputted onto a desired surface. By providing the two compartments with different predetermined transverse cross-sectional areas, a movement of the piston over a given length expresses different volumes of the components at a volume ratio corresponding to the different transverse cross-sectional areas. Therefore, the shape and dimensions of the cartridge can be determined to ensure that the components are expressed at the desired mixing ratio, for example the desired mixing ratio between the curable resin component and the curing agent component.

[005] However, these known cartridges and mixing and dispensing systems suffer from the problem that when at least one of the components has a low viscosity, or when the two components have a large difference in viscosity, control of the flow of the two components can be difficult reliably and repeatably to achieve. This can result in migration or backflow of the low viscosity component, back towards or into the cartridge, which can cause crosscontamination and premature curing.

[006] Also, such loss of control of the flow of the components can lead to an incorrect mixture ratio between the curable resin component and the curing agent in the mixture expressed from the mixing and dispensing system.

[007] Furthermore, the loss of control of the flow of the components can lead to a pressure build up within the mixing and dispensing system, which can cause back flow of a component into the cartridge, or excess or uncontrolled flow of the mixture out of the mixing and dispensing system. [008] Most curable resin systems are formulated for application in a given temperature range. The viscosity of the resin (A) & curing agent (B) components can vary with temperature. Known cartridges and mixing and dispensing systems suffer from the problem that variations in the application temperature can affect the ability of the operator reliably and repeatably to achieve the precise desired mixture ratio without problems of contamination or premature resin curing in the cartridge or the mixing and dispensing system.

[009] If the resin system is mixed “off-ratio”, then either the curable mixed(A+B) material does not solidify, or the overall performance of the mixed composite material, adhesive or filler system is decreased, causing scrap products, waste and an increased risk of lower performance. As a general rule, too low an amount of the curing agent (B) for a given amount of resin (A) may cause an insufficient or reduced cure of the resin material, with unacceptable or reduced cured product performance, whereas too high an amount of the curing agent (B) for a given amount of resin (A) may cause an excessively exothermic cure or, again, reduced or unacceptable product performance.

[010] The present invention aims to provide a two-component mixing and dispensing system, for precise mixing and dispensing first (A) and second (B) components of a curable resin system from a cartridge, and a kit of parts for fitting to a cartridge containing a first and second components of a curable resin system to form a two-component mixing and dispensing system, which can minimise or eliminate incorrect mixture ratios during the mixing together of resin and hardener of a curable resin system, and subsequent dispensing onto a desired surface.

[Oi l] The present invention also aims to provide such a two-component mixing and dispensing system, and kit of parts, which can be combined or used with a known cartridge and can minimise or avoid premature curing or contamination, which would lead to material waste or incorrect mixture ratios and loss of performance, which may be immediate and/or time related. [012] The present invention also aims to provide such a two-component mixing and dispensing system, and kit of parts, which can be combined or used with a known cartridge in which there is a low viscosity resin component, and/or a large difference in viscosity of the two resin components (A + B), which can nevertheless reliably, repeatably and controllably express resin mixtures at the desired mixture ratio and tolerance to minimise or avoid premature curing or contamination by uncontrolled flow of at least one resin component within the mixing and dispensing system.

[013] Finally, the present invention also aims to provide such a two-component mixing and dispensing system, and kit of parts, which can be combined or used with a variety of known cartridges which may contain resin components which may be selected from components having a wide range of absolute or relative viscosities, and which can be used as a single universal mixing and dispensing system suitable for such a wide variety of resins, thereby ensuring that reliably and repeatably control with less impact of environmental factors which might otherwise affect the resin mixing and dispensing capability that can be achieved irrespective of the resin viscosities.

[014] Accordingly, in a first aspect, the present invention provides a two-component mixing and dispensing system, for mixing and dispensing first and second components of a curable resin system from a cartridge, according to claim 1.

[015] In a second aspect, the present invention provides a kit of parts, for fitting to a cartridge containing a first and second components of a curable resin system to form a two-component mixing and dispensing system, according to claim 2.

[016] Preferred features of these aspects of the present invention are defined in the respective dependent claims.

[017] The preferred embodiments of the present invention particularly relate to apparatus and methods using a two-part curable resin system, comprising a curable resin component and a hardener component, which may be selected from any known thermosetting resin system, such as epoxy resins, vinyl resins, polyester resins, etc. Although an epoxy resin system is described below in the detailed description of the preferred embodiments of the present invention, the present invention has application to any curable resin system, for example for use as an adhesive or filler system, which requires at least two component parts to be weighed in a desired mixture ratio.

[018] The preferred embodiments of the present invention can provide a number of technical advantages over the known cartridge-based mixing and dispensing systems for curable resin systems.

[019] The two-component mixing and dispensing system of the preferred embodiments of the present invention is lightweight, mobile and requires no extensive training to use. The two-component mixing and dispensing system of the preferred embodiments of the present invention has particular application for the in situ blade repair of wind turbine blades. This is because the system is light and easily to handle manually, and the system ensures that the required mixture ratio is reliably and repeatably expressed from the system onto the surface of the wind turbine blade, without contamination, premature curing or excess resin outflow from the system.

[020] The two-component mixing and dispensing system can readily use a wide range of commercial cartridges already available from different manufacturers, and the two- component mixing and dispensing system can achieve reliable results even though the viscosity of the resin components may vary from cartridge to cartridge for use in the same cartridge gun.

[021] The kit of parts can be easily assembled on site. After use, the parts of the system which have been in contact with the flowing resin from the cartridge can be collected and disposed of as controlled waste, preferably for recycling where possible.

[022] Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:-

Figure 1 is a schematic side view of a two-component mixing and dispensing system in accordance with an embodiment of the present invention;

Figure 2 is a schematic cross-section from above through the cartridge in the system of Figure 1; Figure 3 is a detailed schematic exploded perspective view of the adapter assembly and a cartridge outlet in the system of Figure 1; and

Figure 4 is a detailed schematic exploded side view of the kit of parts for connection to a cartridge, which is then mounted in a cartridge gun, for forming the system of Figure 1.

[023] In the Figures, which are highly schematic, many components and features are not shown to scale for the sake of clarity of illustration.

[024] Referring to the Figures, there is illustrated a two-component mixing and dispensing system, designated generally as 2, in accordance with a preferred embodiment of the present invention.

[025] The two-component mixing and dispensing system 2 comprises a cartridge gun 4. The cartridge gun 4 comprises an elongate holder 6 for holding a cartridge 8.

[026] In Figure 1 the cartridge 8 is shown separate from the holder 6, but in use the cartridge 8 is installed in the holder as represented by the arrow A in Figure 1.

[027] The cartridge 8 comprises first and second flexible film bags 10, 12. The first flexible film bag 10 defines a first interior cavity 14 containing a first component 16 of a curable resin system. The first flexible film bag 10 has a first closed rear end 18 and a first open front end 20. The second flexible film bag 12 defines a second interior cavity 14a containing a second component 16a of the curable resin system. The second flexible film bag 12 has a second closed rear end 18a and a second open front end 20a.

[028] The first and second flexible film bags 10, 12 are typically composed of a polymer film, for example a multilaminar film, for storing the respective components of the curable resin system.

[029] The curable resin system is typically a thermosetting region, such as an epoxy resin, and for example the first component 16 is the curable epoxy resin and the second component 16a is a curing agent for the epoxy resin. The present invention may be used with other curable resin systems, for example comprising a curable resin component and a hardener component, which may be selected from any known thermosetting resin system, such as epoxy resins, vinyl resins, polyester resins, etc. Although the present embodiment is disclosed with respect to a two-component system, the present invention may also be modified for use in a multiple component system having more than two components (A + B), for example three (A, B + C) components. The present invention has application to any resin system which requires at least two component parts to be mixed and applied in a desired ratio.

[030] A rigid front part 22 of the cartridge 8 is connected to the first and second open front ends 20, 20a. The rigid front part 22 is typically composed of an injection moulded polymer, for example polypropylene. The first and second flexible film bags 10, 12 extend rearwardly of the rigid front part 22 in a side-by-side relationship (as illustrated) or alternatively in coaxial relationship. The rigid front part 22 comprises an outlet 24 extending forwardly of the rigid front part 22. The outlet 24 defines a circumferential outer wall 26 and a separator wall 28 extending transversely across the outlet 24 between opposite sides 30, 30a of the circumferential outer wall 26 to define first and second outlet openings 32, 32a in the outlet 24. The first and second outlet openings 32, 32a are in fluid communication with, respectively, the first and second interior cavities 14, 14a.

[031] The elongate holder 6 holds the first and second flexible film bags 10, 12 of the cartridge 8 so that the rigid front part 22 is located at a front end 34 of the holder 6.

[032] The cartridge gun 4 further comprises a piston mechanism 36 which is movable along the holder 6. A trigger mechanism 38 engages with the piston mechanism 36 and can be operated (shown by arrow B) to move the piston mechanism 36 along the holder 6 (shown by arrow C) in a direction towards the front end 34 of the holder 6. For clarity the mechanism linking the trigger mechanism 38 to the piston mechanism 36, and other structural elements of the cartridge gun 4, are not shown. When the cartridge 8 is located in the holder 6 as described above, the forward motion of the piston mechanism 36 compresses the first and second flexible film bags 10, 12 in the holder 6 to express a mixture of the first and second components 16, 16a of the curable resin system out of the first and second flexible film bags 10, 12. Other mechanisms to the trigger mechanism for moving the piston mechanism described herein can alternatively be employed in accordance with this invention.

[033] The above-described features and operation of the cartridge gun 4 and the cartridge 8 are known to persons skilled in the art.

[034] In accordance with the present invention, the mixing and dispensing system 2 is modified by the provision of a specific assembly downstream of the outlet 24 of the cartridge 8. This specific assembly is configured to control the flow and mixing of the two components of the curable resin system after exiting the outlet 24 of the cartridge 8, particularly when the two components of the curable resin system differ significantly in viscosity and/or when at least one of the components has a low viscosity.

[035] The present invention has particular utility when the first component 16 of the curable resin system has a viscosity within the range of from 600 to 5600 cPs (centiPoises), optionally from 1000 to 2000 cPs, and the second component 16a of the curable resin system has a viscosity within the range of from 30 to 1000 cPs, optionally from 100 to 500 cPs, and preferably the viscosity of the first component 16 is higher than the viscosity of the second component 16a. Alternatively or additionally, for example, the first and second components 16, 16a of the curable resin system differ in viscosity within the range of from 500 to 5500 cPs, optionally from 800 to 1600 cPs.

[036] In a particularly preferred embodiment, the curable resin system is an epoxy resin wet laminating system sold by Gurit (UK) Limited, Newport, UK, under the trade name Ampreg ® 30 in which the first component is the epoxy resin component which has a viscosity within the range of from 1300 to 1700 cPs, and the second component is the hardener component which may be (i) a fast hardener which has a viscosity within the range of from 300 to 500 cPs; or (ii) a standard hardener which has a viscosity within the range of from 100 to 200 cPs.

[037] In the present specification, all of the disclosed viscosity values were measured using a Brookfield CAP2000 viscometer, which is a cone and plate viscometer, and all measurements were taken at 25 °C The measurements are recorded in triplicate, and a mean average value calculated from the three results to provide the final viscosity value. For the first epoxy resin component, and in particular for the epoxy resin component of the Ampreg ® 30 resin system described above, the Brookfield CAP2000 viscometer used a cone type “Cone 1” at a rotational velocity of 50 rpm, and the measurement was conducted for 20 seconds; for the second hardener component the Brookfield CAP2000 viscometer used (a) for the fast hardener of the Ampreg ® 30 resin system described above and for hardeners having viscosities above 250 cPs, a cone type “Cone 2” at a rotational velocity of 150 rpm, and the measurement was conducted for 25 seconds; or (b) for the standard hardener of the Ampreg ® 30 resin system described above and for hardeners having viscosities below 250 cPs, a cone type “Cone 1” at a rotational velocity of 1000 rpm, and the measurement was conducted for 20 seconds.

[038] The specific assembly is configured so as to avoid backflow of any low viscosity component back into the outlet 24 of the cartridge 8 which could cause premature curing and blockage of the outlet 24 by cured resin. The specific assembly is also configured to achieve homogeneous mixing of the two components downstream of the outlet 24 of the cartridge 8. Furthermore, specific assembly is also configured to control the fluid pressure within the specific assembly downstream of the outlet 24 of the cartridge 8 to avoid or minimise backflow and to avoid or minimise uncontrolled outflow of the curable resin from the mixing and dispensing system 2.

[039] These technical effects and advantages are achieved by providing the specific assembly described below.

[040] The two-component mixing and dispensing system 2 therefore additionally comprises, as the specific assembly described above, an adapter assembly 40 fitted to the outlet 24 of the cartridge 8. The adapter assembly 40 is constructed to prevent reverse flow of either of the first and second components 16, 16a, in particular the lower viscosity component, into the outlet 24 of the cartridge 8, which would otherwise cause premature curing and blockage of the outlet 24 by cured resin. [041] A tube 42, having a mixing element 44 disposed within the tube 42, is fitted to the adapter assembly 40. The mixing element 44 achieves homogeneous mixing of the two components downstream of the outlet 24 of the cartridge 8.

[042] A first valve mechanism 46 comprising a stop valve 48 is provided at the outlet 50 of the tube 42 and a second valve mechanism 52 is connected to an outlet side 54 of the first valve mechanism 46. The second valve mechanism 52 is configured to dispense a mixture of the first and second components 16, 16a of the curable resin system from the mixing and dispensing system 2 and to prevent or minimise inadvertent outflow or dripping of the curable resin system from the mixing and dispensing system 2, for example when the trigger mechanism 38 is disengaged. The first valve mechanism 46 and the second valve mechanism 52 control the fluid pressure and flow direction within the specific assembly downstream of the outlet 24 of the cartridge 8 to avoid or minimise backflow and to avoid or minimise uncontrolled outflow of the curable resin from the mixing and dispensing system 2.

[043] In an alternative embodiment, the second valve mechanism 52 is omitted and the outlet side 54 of the first valve mechanism 46 is left unrestricted. In use, the outlet side 54 of the first valve mechanism 46 may be permitted to allow a flow of the curable resin system from the mixing and dispensing system 2 onto or into an applicator mechanism (not illustrated), for example a roller mechanism, for applying a coating of the curable resin system onto s substrate.

[044] In greater detail, as shown in Figure 3, the adapter assembly 40 comprises first and second flow channel members 56, 56a which are, in use, inserted, respectively, into the first and second outlet openings 32, 32a. Each of the first and second flow channel members 56, 56a defines a respective first or second flow channel 58, 58a. Each of the first and second flow channels 58, 58a has a rear opening 60, 60a (shown in phantom in Figure 3) in fluid communication with, respectively, the first and second interior cavities 14, 14a, and a front opening 62, 62a located forwardly of the outlet 24.

[045] In the illustrated embodiment, the first and second flow channel members 56, 56a comprise separate moulded elements. The first and second flow channel members 56, 56a each comprise an annular body 64, 64a surrounding the respective first or second flow channel 58, 58a. The annular body 64, 64a has an external peripheral surface 66, 66a which is semi-circular in cross- section. In use, the annular body 64, 64a is slidingly and sealingly fitted into a respective one of the respective first or second outlet openings 32, 32a which is also semi-circular in cross-section. In this specification, the term “annular” is to be construed as meaning, in general, ring-like with any peripheral shape or geometry, which is not necessarily circular in geometry.

[046] Typically, the first and second flow channels 58, 58a have the same shape and dimensions. The first and second flow channels 58, 58a preferably each have a circular cross-section. The first and second flow channels 58, 58a may each have a diameter of from 3 to 6 mm, for example from 3.5 to 4.5 mm. Typically, the cross-sectional area of each of the first and second flow channels 58, 58a is from 10 to 15 mm ² .

[047] In some embodiments, the cross-sectional area of each of the first and second flow channels 58, 58a is less than 50% optionally less than 30%, further optionally less than 30%, of the cross-sectional areas of the respective first or second outlet openings 32, 32a.

[048] In one preferred embodiment, the outlet 24 has an internal diameter of about 15 mm and each of the first and second outlet openings 32, 32a in the outlet 24 has a semicircular cross-section with a cross-sectional area of about 85 mm ² . Each of the first and second flow channels 58, 58a has a circular cross-section and a diameter of about 4 mm, so that the cross-sectional area of each of the first and second flow channels 58, 58a is about 14 mm ² . Therefore, the cross-sectional area of each of the first and second flow channels 58, 58a is about 16.5%, of the cross-sectional areas of the respective first or second outlet openings 32, 32a.

[049] This reduction in cross-sectional area provides that the first and second flow channels 58, 58a can function as flow restrictors for the flow of resin components out of the cartridge 8. Since the resin mixture ratio is essentially determined by the ratio of the cross-sectional areas of the flexible film bags 10, 12, the first and second flow channels 58, 58a do not directly modify the mixture ratio. However as described herein, the first and second flow channels 58, 58a function to ensure that the correct mixture ratio is reliably and repeatably achieved.

[050] A separator element 66 of the adapter assembly 40 is, in use, connected to at least one of the first and second flow channel members 56, 56a. The separator element 66 comprises a longitudinal wall 68 which extends forwardly of the front openings 62, 62a of the first and second flow channel members 56, 56a. In the illustrated embodiment, the separator element 66 is integrally moulded with one of the first and second flow channel members 56, 56a. However, in one alternative embodiment the separator element 66 and the first and second flow channel members 56, 56a may each be individually moulded, and the three elements are assembled together, or in another alternative embodiment the separator element 66 and the first and second flow channel members 56, 56a are all integrally moulded, and the three elements are moulded together as a one-piece moulding. The moulded elements may be injection moulded, or shaped by three-dimensional printing, or made by any other suitable manufacturing technique. The separator element 66 and the first and second flow channel members 56, 56a are typically composed of a polymer, such as polypropylene.

[051] An annular fixing member 70 of the adapter assembly 40 has rear and front ends 72, 74 and an inner circumferential surface 76. In use, the rear end 72 is fitted, preferably by means of a threaded fitting, by the inner circumferential surface 76 to an outer circumferential surface 78 of the circumferential outer wall 26 of the outlet 24 of the cartridge 8. The front end 72 has a fluid outlet 80.

[052] The longitudinal wall 68 of the separator element 66 extends forwardly through the fluid outlet 80 of the annular fixing member 70. Opposite longitudinal edges 84, 84a of the longitudinal wall 68 engage opposite sides 86, 86a of the inner circumferential surface 76. The longitudinal wall 68 extends forwardly into the fluid outlet 80 whereby the longitudinal wall 68 transversely divides an internal bore 88 of the fluid outlet 80 into two separate first and second outlet orifices 90, 90a. Preferably, a free end 82 of the longitudinal wall 68 is located forwardly of the annular fixing member 70. Typically, the free end 82 of the longitudinal wall 68 is located forwardly of the annular fixing member 70 by a distance of at least 5 mm, for example a distance of from 5 to 10 mm. Typically, the free end 82 of the longitudinal wall 68 is located forwardly of the separator wall 28 in the outlet 24 of the cartridge by a distance of at least 15 mm, for example a distance of from 15 to 30 mm. In one particularly preferred embodiment, the free end 82 of the longitudinal wall 68 is located forwardly of the annular fixing member 70 by a distance of 7 mm, and the free end 82 of the longitudinal wall 68 is located forwardly of the separator wall 28 in the outlet 24 of the cartridge by a distance of 21 mm.

[053] Typically, the annular fixing member 70 is composed of injection moulded or otherwise manufactured polymer, for example polypropylene.

[054] Referring to Figure 4, the tube 42 has a rear end part 92 fitted to the front end 74 of the annular fixing member 70 so that first and second outlet orifices 90, 90a are in fluid communication with the tube 42. Preferably, the rear end part 92 of the tube 42 is, using a threaded fitting, fitted to the front end 74 of the annular fixing member 70. The mixing element 44 disposed within the tube 42 is preferably a static mixing element 44, which comprises a series of a plurality of blade elements 93 inclined to the longitudinal direction of the tube 42. Such static mixing elements, optionally pre-assembled into tubes, are well- known to those skilled in the art of cartridge systems for curable resins. The tube 42 is preferably flexible and transparent or translucent, and composed of a polymer, for example polyethylene or polypropylene. The tube 42 may have a circular or other, e.g. square, cross-section, and the static mixing element 44 has a corresponding cross-sectional shape and dimensions to fit the elongate internal cavity in the tube 42. Typically, the tube 42 has a square cross-section which has internal dimensions of 10 mm x 10 mm.

[055] The first valve mechanism 46 comprises stop valve 48 which is switchable between open and closed positions, and preferably comprises a ball valve. The first valve mechanism 46 has an inlet side 94 connected to a front end part 96 of the tube 42, for example by a clamp mechanism 97.

[056] The second valve mechanism 52 is connected to the outlet side 54 of the first valve mechanism 46. As described above, the second valve mechanism 52 is configured to dispense a mixture of the first and second components 16, 16a of the curable resin system from the mixing and dispensing system 2 and to control the flow of the mixture of the first and second components 16, 16a to prevent inadvertent outflow or dripping of the curable resin system from the mixing and dispensing system 2, for example when the trigger mechanism 38 is disengaged. Preferably, the second valve mechanism 52 is a duckbill valve mechanism, typically composed of a silicone polymer. As stated above, in an alternative embodiment, the second valve mechanism 52 is omitted and the outlet side 54 of the first valve mechanism 46 is left unrestricted, so that in use, the outlet side 54 of the first valve mechanism 46 may be permitted to allow a flow of the curable resin system from the mixing and dispensing system 2 onto or into an applicator mechanism (not illustrated), for example a roller mechanism, for applying a coating of the curable resin system onto s substrate.

[057] In accordance with the preferred embodiments of the present invention, the adapter assembly 40, the tube 42, the mixing element 44, the first valve mechanism 46 and the second valve mechanism 52 may be provided in fully assembled, partially assembled or disassembled form as a kit of parts for fitting to a cartridge 8 containing the first and second components 16, 16a of a curable resin system to form the two-component mixing and dispensing system 2, when combined with the cartridge gun 4 as described above.

[058] In use, typically the adapter assembly 40, the tube 42, the mixing element 44, the first valve mechanism 46 and the second valve mechanism 52 are provided in a disassembled form, as shown in Figure 4. The tube 42, the first valve mechanism 46 and the second valve mechanism 52 can be fitted together using clamps or other conventional fittings. The mixing element 44 is then inserted into the tube 42. Alternatively, the mixing element 44 and the tube 42 may be provided in a pre-assembled form, and such preassembled static mixers are well-known to those skilled in the art and commercially available from various suppliers. Then the tube 42 is fitted to the assembled adapter assembly 40. A seal membrane (not shown), or other protective cover, over the outlet 24 of the cartridge 8 is removed, and then the adapter assembly 40 is fitted to the outlet 24.

[059] The first and second flow channel members 56, 56a have a selected dimension, in particular with a selected dimension of the flow channel 58, 58a, which can be individually selected based on the known viscosity on the individual resin components 16, 16a in the cartridge 8 to be used. In this way, the first and second flow channel members 56, 56a can function as customised flow restrictors, having known flow control properties for any given reason component viscosity flowing therethrough. This can provide flow control to prevent any component migrating back into the cartridge 8, thereby avoiding cross contamination, premature curing and incorrect mixture ratios.

[060] The longitudinal wall 68 of the separator element 66 also has an important function to provide flow control to prevent any component migrating back into the cartridge 8, thereby avoiding cross contamination, premature curing and incorrect mixture ratios. The longitudinal wall 68 extends forwardly through the fluid outlet 80 of the annular fixing member 70, and preferably the free end 82 of the longitudinal wall 68 is located forwardly of the annular fixing member 70. The opposite longitudinal edges 84, 84a of the longitudinal wall 68 engage opposite sides 86, 86a of the inner circumferential surface 76. The longitudinal wall 68 therefore transversely divides an internal bore 88 of the fluid outlet 80 into two separate first and second outlet orifices 90, 90a, and over a length which is at least the length of the separator element 66, defines two entirely separated outlet bore portions 100, 100a, shown in phantom in Figure 4, which are external of the cartridge 8. The location of the longitudinal wall 68 within the fluid outlet 80 is calculated and manufactured, taking into consideration the shape and dimensions of the first and flexible film bags 10, 12 and the piston mechanism 36, so that the two separate first and second outlet orifices 90, 90a have a predetermined ratio of cross-sectional areas corresponding to the desired mixing ratio of the first and second components of the curable resin system, for example a volume ratio of epoxy resin componenthardener component of 3:1.

[061] This function of the adapter assembly 40 to provide an extended length physical separation of the resin components provides the technical effect that when the piston pressure is removed after a resin dispensing operation, even if there is some pullback of resin components towards and into the cartridge 8 or the outlet 24 of the cartridge 8 as a result of reduced hydraulic pressure in the cartridge 8, or a reverse resin flow for any other reason, such pullback or reverse flow would not result in resin contamination. This is because the extended length of the separator element 66 would be sufficient to prevent one resin component from moving in a reverse direction over a distance larger than the length of the separator element 66, and therefore the reverse flow cannot enter the incorrect cavity 14, 14a or outlet 24 of the cartridge 8. This technical effect of avoiding problems associated with reverse resin flow can be achieved irrespective of the viscosity of the resin components in the cartridge 8, because the physical separation between the two components externally of the cartridge 8 can extend over a significant distance which can accommodate the increased flow of a low resin component.

[062] In a preferred embodiment, the system 2 and the kit of parts may comprise a plurality of pairs of the first and second flow channel members 56, 56a, each pair having a respective selected dimension of the flow channel 58, 58a. Each pair of the first and second flow channel members 56, 56a could be designed for use with a given pair of resin components 16, 16a. In this way, the kit of parts can provide a universal kit for use with a wide range of cartridges 8 comprising different resin formulations with different viscosities.

[063] The first and second flexible film bags 10, 12 of the cartridge may initially be fitted into a rigid elongate sleeve (not shown), for example composed of aluminium, which is shaped and dimensioned to fit within the elongate holder 6 of the cartridge gun 4, as is well-known to those skilled in the art. Then the cartridge 8 (and sleeve if provided) is inserted into the cartridge gun 4. The ball valve of the first valve mechanism 46 is opened. The trigger mechanism 38 is operated to move the piston mechanism 36 to compress the first and second flexible film bags 10, 12 and express the two resin components 16, 16a of the curable resin system at the desired mixture ratio out of the cartridge 8 through the outlet 24. The two resin components 16, 16a are mixed by the mixing element 44 and the continuous flow of the mixture through the tube 42 and through the ball valve is controlled by opening or closing the ball valve, which also controls pressure within the tube 42, and thereby also prevents pressure build-up which could also cause reverse flow or excess outflow from the duckbill valve of the second valve mechanism 52. The duckbill valve prevents or minimises dripping and spills of the resin mixture from the mixing and dispensing system 2, but as described above this duckbill valve could be omitted, particularly if the output of the mixing and dispensing system is coupled to an applicator such as a roller mechanism.

[064] Various modifications to the preferred embodiments of the present invention, as defined by the appended claims, will be apparent to those skilled in the art.