AU2007217689A1

AU2007217689A1 - Process for colouring plastics by feeding liquid colour from feed equipment, and container for liquid colour comprising at least one machine-readable memory element

Info

Publication number: AU2007217689A1
Application number: AU2007217689A
Authority: AU
Inventors: Maurice Weelen; Martin Welp
Original assignee: Evonik Degussa GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2006-02-21
Filing date: 2007-02-07
Publication date: 2007-08-30
Also published as: EP1820568A1; KR20080109729A; WO2007096248A1; CN101389465A; MA30280B1; EP1986836A1; ZA200807194B; CA2643213A1

Description

IN THE MATTER OF an Australian Application corresponding to PCT Application PCT/EP2007/051171 RWS Group Ltd, of Europa House, Marsham Way, Gerrards Cross, Buckinghamshire, England, hereby solemnly and sincerely declares that, to the best of its knowledge and belief, the following document, prepared by one of its translators competent in the art and conversant with the English and German languages, is a true and correct translation of the PCT Application filed under No. PCT/EP2007/051171. Date: 16 June 2008 C. E. SITCH Managing Director - UK Translation Division For and on behalf of RWS Group Ltd Process for the coloring of plastics with liquid colorant and liquid colorant container suitable for this purpose The invention relates to a process for the coloring of 5 plastics in a continuously operated extruder or an intermittently operating injection-molding machine, and to a liquid colorant container suitable for the process, which can be used to achieve consistent and reproducible coloring of plastics, even with a liquid colorant that has not been 10 precisely standardized. The feeding of liquid colorant into a continuously operated extruder or an intermittently operating injection-molding machine is a simple method of coloring plastics during their processing. Use of liquid colorant in this way can 15 avoid maintaining inventory of colored plastics. In order to achieve consistent and reproducible results when coloring with liquid colorant, the usual method uses liquid colorants with standardized properties and meters the liquid colorants for production of a certain color in 20 each case with constant weight or volume. However, standardization of the properties of a liquid colorant requires additional operations and is particularly difficult in the case of liquid colorants which are metered not only by weight but also by volume, and for which it is 25 therefore not only the color strength that has to be standardized but also the density of the liquid colorant. WO 02/087849 discloses a process in which one or more liquid colorants are introduced into a continuously operated plastics-processing machine, where the metering of 30 the liquid colorant takes place with a metering device according to fixedly prescribed formulations. DE 197 28 733 Al discloses a process in which liquid 2 colorant is metered into the conveying path of the injection material, leading to the mold cavities, in an intermittently operating injection-molding machine. Prescribed amounts of liquid colorant are metered here. 5 In both of the known processes, differences in the substance properties of the liquid colorant which have an effect on its color strength inevitably lead to deviations in the coloring of the plastic. DE 35 05 036 Al discloses a process for the controlled 10 addition of colorant concentrates into a screw-based machine, where a spectrometer attached to the screw-based machine is used to measure the color intensity of the colored mixture, and the measured signal is used to control the addition of solid colorant concentrates to the screw 15 based machine. The process achieves uniform coloring in the event of variations in the color strength of the colorant concentrates, but requires modification of the machine with an expensive spectrometer. EP 131 414 describes a method for the production of color 20 mixtures by using a metering device to meter dye from a container which comprises a memory element in which information relating to the color properties of the dye is stored. In this method, the metering device reacts to information stored in the memory element in order to meter 25 an amount of dye required to achieve the prescribed color. EP 131 414 contains no reference to coloring of plastics. There continues to be a need for a process which uses liquid colorant for the coloring of plastics and which dependably achieves a consistent and reproducible result 30 during the coloring process, even when using a liquid colorant which has not been precisely standardized. It has now been found that this object can be achieved by a process in which liquid colorant is metered from a 3 container which has a machine-readable memory element in which data relating to substance properties of the liquid colorant present in the container are stored, where the metering device reads from the memory element of this 5 container data relating to substance properties of the liquid colorant and uses the read data to adjust or control the amount of liquid colorant metered. The invention provides a process for the coloring of plastics by metering of liquid colorant from a liquid 10 colorant metering device, connected to least one liquid colorant container, into a continuously operated extruder or an intermittently operating injection-molding machine, characterized in that at least one container is used which comprises at least one machine-readable memory element in 15 which data on substance properties of the liquid colorant present in the container are stored, and the metering device reads from the machine-readable memory element of the container at least a portion of the data on substance properties of the liquid colorant present in the container, 20 and adjusts or controls the amount of liquid colorant metered with the read data. The invention also provides a liquid colorant container comprising at least one machine-readable memory element in which data on substance properties of the liquid colorant 25 present in the container are stored, wherein data on the density of the liquid colorant are stored in the machine readable memory element. The process of the invention uses a liquid colorant container which comprises at least one machine-readable 30 memory element. For the purposes of the invention, machine readable memory elements are those from which a data processing system can read data directly. Printed barcodes are an example of machine-readable memory elements from which a data-processing system can read data directly and 35 optically, whereas printed text is not a machine-readable 4 memory element for the purposes of the invention, since the data present in the text cannot be directly read into a machine. Machine-readable memory elements preferably used are 5 barcodes, magnetic strips, electrically contacted memory elements, and memory elements readable via radio frequency. The machine-readable memory elements used can be memory elements that are only readable, examples being barcodes or ROM memory elements. Writable memory elements are equally 10 suitable, examples being magnetic strips or EEPROM memory elements. A preferred embodiment uses memory elements readable via radio frequency which are known to the person skilled in the art as RFID tags. In one embodiment of the invention, the design of the 15 liquid colorant container is such that when the container is connected to a metering device for the liquid colorant, the machine-readable memory element is oriented in a predetermined orientation with respect to the metering device so that the metering device can read data from the 20 memory element. Data on substance properties of the liquid colorant present in the container are stored in the machine-readable memory element. Preferably, data on one or more of the following properties are stored in the memory element: hue, color 25 strength, lightness, color saturation, hiding power, transparency, and density of the liquid colorant. The data relating to hue, lightness, and color saturation are preferably stored in the form of the parameters L, a, and b, or the parameters L, Cab, and hab of the CIELAB system, 30 or the parameters X, Y, and Z corresponding thereto. Further data on the liquid colorant present in the container may also be stored in the machine-readable memory element, such as for example the weight of the liquid colorant present in the container, or one or more product 5 identification numbers. In the process of the invention, at least one liquid colorant container is connected to a liquid colorant metering device. The data on properties of the liquid 5 colorant present in the container are read completely or in part by the metering device and the amount of liquid colorant metered is adjusted or controlled with these data. The reading of the data can be brought about by the user of the metering device, for example in that the user reads the 10 data with a barcode-reader from a barcode attached to the container and transfers the data from the barcode-reader to the metering device. In another embodiment, the reading of the data takes place automatically upon connecting the container to the metering 15 device, for example by a coupling between the container and the metering device which electrically contacts the memory element, or by an RFID tag reader integrated into the metering device. It is preferable that with an exchange of a liquid colorant container the-metering device 20 automatically reads data from the machine-readable memory element of the container newly connected to the metering device. Preferably, metering devices in which the metering of the liquid colorant takes place continuously or intermittently 25 at constant flow rates are used in the process of the invention. In a preferred embodiment of the process of the invention, the metering device reads from the memory element of the container data on the density of the liquid colorant 30 present in the container and adjusts or controls volumetric metering of the liquid colorant with the read data. This embodiment allows consistent and reproducible coloring using liquid colorants, which have been standardized to a 6 constant color strength based on weight, and do not have a precisely standardized density. This embodiment particularly preferably uses commercially available liquid colorant containers which are additionally labeled with a 5 barcode in which the density of the liquid colorant present in the container is stored. This embodiment permits the use of commercially available liquid colorants, standardized to a constant color strength based on weight, with metering devices with volumetric metering of the liquid colorant. 10 In another preferred embodiment of the process of the invention, the metering device reads from the machine readable memory element data on the weight of the liquid colorant present in the container and uses the read data to monitor the residual amount of liquid colorant in the 15 container. This embodiment can reliably avoid unintended stoppage of colorant metering when the container has been emptied, even when containers with different filling weight are used. When writable memory elements are used, it is moreover possible to save in the memory element the 20 remaining residual amount of liquid colorant in the container. This permits changeover between only partly filled containers and permits monitoring of the remaining residual amount in the container even when the metering device is connected to a container which is only partly 25 filled and avoidance of unintended emptying of the container during the metering process. In another preferred embodiment of the process of the invention, the metering device is connected to at least two liquid colorant containers and mixes at least two liquid 30 colorants with one another. Each of the containers connected to the metering device has a machine-readable memory element, in which data on the hue of the liquid colorant present in the container are stored, and the metering device adjusts or controls the mixing ratio of the 35 liquid colorants with the read data.

7 It is preferable that, in addition to the hue, data on lightness and color saturation in the form of the parameters L, a, and b, or the parameters L, Cab, and hab of the CIELAB system, or the parameters X, Y, and Z 5 corresponding thereto are stored in the memory element. Using the read data, and setpoint values for the parameters L, a, and b, or L, Cab, and hb, or the parameters X, Y, and Z corresponding thereto, of the liquid colorant, deposited in the metering device, a correction for the mixing ratio 10 can be calculated in the metering device to obtain a mixed liquid colorant, which achieves a consistent and reproducible coloring even in the event of deviations of the parameters L, a, and b, or L, Cab, and hab or the parameters X, Y, and Z corresponding thereto, from the 15 specified value. The correction can sometimes also require the metering of further liquid colorants which are not required for the formulation with the specified values. The person skilled in the art is aware of suitable methods for the calculation of the correction, for example from G. A. 20 Klein, Farbenphysik filr industrielle Anwendungen [Color physics for industrial applications], Verlag Springer. Using this embodiment, it is possible to obtain a mixed liquid colorant which achieves a consistent and reproducible coloring even starting from liquid colorants 25 which have not been precisely standardized. Even when using standardized liquid colorants, this embodiment of the inventive process can achieve an even better reproducibility of the coloring, because deviations from the specified value, which remain even after 30 standardization, can be compensated during the metering process. The process of the invention can achieve consistent and reproducible coloration of preparations in the form of liquids, pastes, powders, or granules, even when using 35 liquid colorants which have not been precisely standardized.

Claims

1. A process for the coloring of plastics by metering of liquid colorant from a liquid colorant metering device, connected to at least one liquid colorant container, 5 into a continuously operated extruder or an intermittently operating injection-molding machine, characterized in that at least one container is used comprising at least one machine-readable memory element in which data on 10 substance properties of the liquid colorant present in the container are stored, and the metering device reads from the machine-readable memory element of the container at least a portion of the data on substance properties of the liquid colorant present in the 15 container and adjusts or controls the amount of liquid colorant metered with the read data.

2. The process of claim 1, characterized in that the data stored in the machine-readable memory element 20 have been selected from data on hue, color strength, lightness, color saturation, hiding power, transparency, and density of the liquid colorant, and combinations thereof.

3. The process of claim 1 or 2, 25 characterized in that data on the density of the liquid colorant present in the container are stored in the machine-readable memory element and the metering device adjusts or controls volumetric metering of the liquid colorant with the 30 read data.

4. The process of one of claims 1 to 3, characterized in that additionally data on the weight of the liquid colorant present in the container are stored in the machine- 9 readable memory element and the metering device monitors the residual amount of liquid colorant in the container with the read data.

5. The process of one of claims 1 to 4, 5 characterized in that the metering device is connected to at least two liquid colorant containers and mixes at least two liquid colorants with one another, and each of the containers has a machine-readable memory element, in which data on 10 the hue of the liquid colorant present in the containers are stored, and the metering device adjusts or controls the mixing ratio of the liquid colorants with the read data.

6. The process of one of claims 1 to 5, 15 characterized in that the machine-readable memory element is selected from the group of barcodes, magnetic strips, electrically contacted memory elements, and memory elements readable via radio frequency. 20

7. The process of one of claims 1 to 6, characterized in that during a change of a liquid colorant container, the metering device automatically reads data from the machine-readable memory element of the container newly 25 connected to the metering device.

8. A liquid colorant container for the coloring of plastics, comprising at least one machine-readable memory element in which data on substance properties of the liquid colorant present in the container are 30 stored, characterized in that data on the density of the liquid colorant are stored in the machine-readable memory element. 10

9. The container of claim 8, characterized in that additionally data on hue, color strength, lightness, color saturation, hiding power, and transparency of the 5 liquid colorant, and combinations thereof, are stored in the machine-readable memory element.

10. The container of claim 9, characterized in that for the liquid colorant parameters L, a, and b, or 10 parameters L, Cab, and hab of the CIELAB system, or the parameters X, Y, and Z corresponding thereto, are stored in the machine-readable memory element.

11. The container of one of claims 8 to 10, characterized in that 15 the machine-readable memory element is selected from the group of barcodes, magnetic strips, electrically contacted memory elements, and memory elements readable via radio frequency.

12. The container of one of claims 8 to 11, 20 characterized in that additional data on the weight of the liquid colorant present in the container are stored in the machine readable memory element.