Delivering liquid additive

Abstract

A reservoir assembly (40) comprises a container (4), a support assembly (42) on which the container (4) is mounted and fixed and a rotary electric vibrator device (44) coupled to the support assembly (42). The container holds a shear thinning additive for a plastics material. The reservoir assembly is arranged so that on operation of the device (44), an appropriate frequency and amplitude of vibration is applied to the container (4) and, therefore, its contents. As a result, a liquid dispersion in the container is shear thinned and recovery of dispersion from the container is increased.

Claims

1. A method of facilitating emptying of a receptacle to improve recovery of a liquid additive composition from the receptacle, the method comprising: (i) selecting the receptacle containing the liquid additive composition which is shear thinning; (ii) releasably securing said receptacle adjacent to an apparatus for delivering the liquid additive composition into a plastics material; (iii) with the receptacle operatively connected to said apparatus for delivering the liquid additive composition into the plastics material, applying vibrational motion to the receptacle to facilitate passage of the liquid additive composition from the receptacle into said apparatus, wherein said vibrational motion is applied using a vibrational device having an operating frequency in the range of 1 Hz to 500 Hz; and (iv) delivering the liquid additive composition from the apparatus into the plastics material; wherein the liquid additive composition delivered in step (iv) is identical to the liquid additive composition contained in the receptacle selected in step (i).

2. A method according to claim 1, wherein said liquid additive composition comprises a vehicle and an active component which it is desired to introduce into a plastics material.

3. A method according to claim 1, wherein said liquid additive composition comprises a vehicle and an active component which is provided as a dispersion in said vehicle; and wherein said active component is selected from colourants, UV filters, oxygen absorbers, antimicrobial agents, acetaldehyde scavengers, reheat additives, anti-oxidants, light stabilisers, optical brighteners, process for stabilizers and flame retardants.

4. A method according to claim 2, wherein said active component is a colourant; and wherein said vehicle is selected from C.sub.9-C.sub.22 fatty acid esters, ethoxylated C.sub.9-C.sub.22 fatty acid esters, ethoxylated alcohols and plasticizers.

5. A method according to claim 1, wherein said liquid additive composition has a viscosity of greater than 20,000 cP.

6. A method according to claim 1, wherein the liquid additive composition has a shear thinning index of at least 1.5.

7. A method according to claim 1, wherein said vibrational motion is applied using the vibrational device which generates a PEAK-PEAK displacement amplitude on a base of the receptacle of 0.01 mm to 10 mm.

8. A method according to claim 1, wherein said receptacle is part of a receptacle assembly which includes the vibrational device for applying vibrational motion to the receptacle, wherein said receptacle assembly comprises the receptacle and a support means therefor, wherein said vibrational device is operatively connected to the support means, and the support means comprises a planar part on which a rim of the receptacle is seated.

9. A method according to claim 8, wherein a securement means is provided for releasably securing the receptacle to the support means so that the receptacle is translationally and rotationally fixed relative to the vibrational device.

10. A method according to claim 9, wherein said securement means is arranged to co-operate with a handle of the receptacle and/or is arranged to co-operate with an outlet of the receptacle.

11. A method according to claim 8, wherein said receptacle assembly is mounted on a movable support by means of which it may be moved towards and away from a plastics processing apparatus.

12. A method according to claim 1, wherein said vibrational motion is operated intermittently while liquid additive composition is flowing during emptying of the receptacle.

13. A method according to claim 12, wherein said vibrational motion is supplied for periods of time of at least 20 seconds, with a delay of at least 6 minutes being defied between periods of supply of vibrational motion.

14. A method according to claim 1, wherein said liquid additive composition is for a thermoplastics polymer.

15. An assembly comprising apparatus for delivering a liquid additive into a plastics material in combination with a receptacle containing a shear thinning liquid additive, the assembly comprising a vibration device for applying vibrational motion to the receptacle to facilitate passage of liquid additive from the receptacle into said apparatus, wherein said receptacle is releasably securable adjacent the apparatus; wherein said receptacle includes an outlet for passage of said liquid additive out of the receptacle, wherein said outlet includes a neck portion and said assembly includes means for releasably engaging the neck portion for releasably securing the receptacle in position.

16. A method according to claim 1, wherein said receptacle includes a handle.

17. A method according to claim 1, wherein the method is used to remove at least 97 wt % of liquid additive composition from the receptacle.

18. A method of facilitating emptying of a receptacle to improve recovery of a liquid additive composition from the receptacle, the method comprising: (i) providing the liquid additive composition which is shear thinning the receptacle; (ii) with the receptacle operatively connected to an apparatus for delivering the liquid additive composition into the plastics material, applying vibrational motion to the receptacle to facilitate passage of the liquid additive composition from the receptacle into said apparatus, wherein said vibrational motion is operated intermittently while liquid additive composition is flowing during emptying of the receptacle, wherein said vibrational motion is applied using a vibrational device having an operating frequency in the range of 1 Hz to 500 Hz; and (iii) delivering the liquid additive composition from the apparatus into the plastics material; wherein the liquid additive composition delivered in step (iii) is identical to the liquid additive composition provided in step (i); and wherein said method is used to recover at least 98 wt % of liquid additive composition from said receptacle.

19. The method of claim 1, wherein the receptacle includes an outlet for passage of the liquid additive out of the receptacle; wherein the outlet includes a neck portion; and wherein an assembly comprising the receptacle and the apparatus further comprises: the vibrational device for applying the vibrational motion; and means for releasably engaging the neck portion for releasably securing the neck portion in position.

20. The method of claim 1, wherein said method is used to recover at least 98 wt % of liquid additive composition from said receptacle.

Description

(1) Specific embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which

(2) FIG. 1 is a schematic representation of a dosing apparatus;

(3) FIG. 2 is a side elevation of a reservoir assembly;

(4) FIG. 3 is a plan view of a support assembly for supporting a container of the reservoir assembly, partly in cross-section;

(5) FIG. 4 is a graph of residual weights v. viscosity index for a range of colour dispersions with and without vibration.

(6) Referring to FIG. 1, a dosing apparatus 2 includes a main additive reservoir assembly 40 described in greater detail with reference to FIGS. 2 and 3, comprising a substantially rigid container 4 which is connected via pipe 6 to an intermediate reservoir 8. The pipe 6 is connected to the container 4 by a dry disconnect valve 10 and is connected to intermediate reservoir 8 via a simple screw-threaded coupling 12. A peristaltic pump 14 cooperates with pipe 6 for pumping fluid from the container 4 to the reservoir 8.

(7) The reservoir 8 comprises a plastics bag which incorporates an opening (not shown) towards an upper end for communication with pipe 6. At its lower end, the reservoir 8 includes an outlet tube 24 which is arranged to deliver fluid to a dosing pump 26.

(8) The dosing pump 26 is arranged to deliver a predetermined quantity of fluid into a process via pipe 28 which may be manipulated to deliver fluid, in the form of liquid colorant, into a plastics material.

(9) Referring to FIG. 2, the reservoir assembly 40 comprises the container 4, a support assembly 42 on which the container 4 is mounted and fixed and a rotary electric vibrator device 44 (a Itlvibras M3/20-so2) coupled to the support assembly 42. The reservoir assembly is arranged so that on operation of the device 44, an appropriate frequency and amplitude of vibration is applied to the container 4 and, therefore, its contents. As a result, a liquid dispersion in the container is shear thinned and recovery of dispersion from the container is increased.

(10) Further details and examples are provided below.

(11) The support assembly 42 is arranged to support the weight of container 4. It comprises a planar horizontal platform 46 made from a sheet material (FIG. 3) which surrounds and defines a circular opening 48. A circular rim of the inverted container 4 rests upon and is supported by platform 46. A conical region 50 of the container 4 extends downwardly through opening 48 so that the container's outlet 52 is positioned centrally within the opening 48 below platform 46.

(12) Stepped beneath platform 46, the support assembly includes a planar support plate 54 which is rigidly secured to the platform 46 by means (not shown) such that the platform 46 and support plate 54 extend parallel to one another. The support plate 54 includes a circular opening 56 which is concentric with the circular opening 48 although opening 56 is of smaller diameter. The support plate 56 is secured to a frame (not shown) of a trolley (not shown) which carries other elements of the apparatus shown in FIG. 1, by means of four isolation mounts 58.

(13) The device 44 is rigidly secured to both the platform 46 and support plate 54 by suitable means (not shown) so that vibrations from the device 44 are transmitted in use to the platform and support plate and, therefore, the container 4 supported on the platform.

(14) The container 4 is rigidly secured to the support assembly 42 in use. To this end, a cam arrangement 60 is provided. The arrangement 60 has a curved surface 62 which extends downwardly, curves inwardly and is aligned with a diameter which is concentric with the circular openings 48, 56. The curved surface is arranged to be engaged by a hand grip portion 64 of a pivotable handle 66 of the container 4 so portion 64 rests within a depression 68 in the surface 62 when suitably positioned. In addition, a catch arrangement 70 is provided to engage discharge connector 72 of the container 4. More particularly, the catch arrangement comprises a planar dog-legged member 74, made of sheet steel, which is pivotably mounted at point 76 on an upwardly facing face of support plate 54 so that it is pivotable between a disengaged position shown in dashed lines in FIG. 3 and an engaged position shown in full lines in FIG. 3. The dog-legged member 74 is positioned so that on pivoting of the member, a mouth 78 thereof moves towards the centre of the openings 48, 56 at which position discharge connector 72 is positioned in use. Thus, member 74 and discharge connecter 72 are arranged such that, in use, the mouth extends around the connector 72 and an area of member 74 around the mouth extends within an annular recess defined in the discharge connector.

(15) The container 4 may be secured to the support assembly 42 as follows. With the dog-legged member 74 in the dashed position shown in FIG. 3, the container 4 with its lid in position, is inverted and positioned centrally within openings 48, 56 so that its rim makes face to face contact with platform 46. Then, the handle 60 of the container is pivoted and the hand grip portion 64 is engaged with and moved down surface 62 until it rests within the depression 68. Next, the dog-legged member 74 is pivoted so its mouth 78 extends around discharge connector 72 and the member 74 cooperates with the annular recess defined in the connector.

(16) In use when the device 44 vibrates, vibration is transmitted to the platform 46, support plate 54 and container 44 so they move as one.

(17) The reservoir assembly 40 may be used to provide a substantial improvement in recovery (yield) of a shear thinning liquid dispersion from the container 4.

(18) A simple test to define whether a formulation is shear thinning is to measure its viscosity at two shear rates and at a temperature of 23 C. If the viscosity of the formulation at the low shear rate is greater than the viscosity at the high shear rate then it exhibits shear thinning rheological behaviour. A term called shear thinning index, defined as the ratio of the low shear viscosity over the high shear viscosity, can be used to compare the shear thinning properties of the fluids. This can be simply determined by measuring the viscosity of the formulation using a Brookfield Viscometer at a low spindle speed (e.g. 2 rpm) and at a high spindle speed (e.g. 20 rpm) and determining the ratio according to the following equation:

(19) $\mathrm{Shear}\mathrm{Thinning}\mathrm{Index}\left(\mathrm{STI}\right)=\frac{\mathrm{Viscosity}\mathrm{at}2\mathrm{rpm}}{\mathrm{Viscosity}\mathrm{at}20\mathrm{rpm}}$

(20) Examples 1 to 6 illustrate operation of the reservoir assembly.

EXAMPLES 1 TO 6

(21) A Brookfield DV-II+ programmable viscometer, model type RVDV-II+, utilizing a #6 spindle was used to measure the viscosity of each formulation at 5 rpm (low-shear rate) and 20 rpm (high-shear rate).

(22) Seven liquid colour products from ColorMatrix Corporation, USA, with various viscosities and a range of shear thinning indices were chosen to illustrate the improved product recovery that can be achieved using the reservoir assembly 40.

(23) Identical 27 liter containers were filled with 18.18 kg of liquid colour dispersions. Two respective containers were filled with each dispersion and the containers were emptied and assessed with and without operation of the vibrator device 44.

(24) In a first series of experiment a peristaltic pump (e.g. pump 14 of FIG. 1) was used to pump dispersion from each container until no more product could be removed. Then the containers were weighed to determine the amount of dispersion remaining. In a second series of experiments, the pump was used as before except in this case the vibrator device was operated continuously. The operating frequency of the device was 50 Hz and the peak-peak displacement amplitude was 1.5 mm. After no more product could be removed from the container, the container was weighed to determine the amount of dispersion remaining. Results are provided in Table 1.

(25) TABLE-US-00001 TABLE 1 Shear Residual Product Brookfield Thining Residual Product (kg) (litre) % Yield Example Density Viscosity (cP) Index Without With Without With Without With No g/cm.sup.3 2 rpm 20 rpm (2/20 rpm) vibration vibration vibration vibration vibration vibration 1 1.98 37000 15000 2.5 0.436 0.327 0.221 0.165 97.6% 98.2% 2 1.12 44500 13800 3.2 0.414 0.191 0.371 0.171 97.7% 99.0% 3 1.69 24500 4800 5.1 0.523 0.241 0.309 0.142 97.1% 98.7% 4 2.19 92000 16100 5.7 1.614 0.686 0.735 0.313 91.1% 96.2% 5 1.24 67500 9500 7.1 3.536 0.173 2.863 0.140 80.6% 99.1% 6 1.06 140000 18,600 7.5 5.555 0.368 5.252 0.348 69.5% 98.0%

(26) The results for Table 1 are graphically represented in FIG. 4. It will be noted from the figure that the residual weight of liquid colorant remaining in the containers without vibration is high, particularly for high viscosity index formulations, whereas that remaining when vibration is used is consistently low.

(27) The residual product remaining in the containers without vibration varies considerably from 414 g to 5.555 kg which equates to product recovery yields of 97.6% to 69.5% respectively.

(28) With vibration, the residual product, in all cases is reduced, ranging from 173 g to 686 g which equates to product recovery yields of 99.1% to 96.2% respectively.

(29) The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.