DE102008019176A1 - Method for manufacturing plastic containers, by premolding of plastic material, involves determining infrared absorption factor on area of plastic - Google Patents

Abstract

The method involves determining the infrared absorption factor on an area of plastic and subsequently a value characterizing the infrared absorption factor is used in the manufacturing of the containers. The infrared absorption factor is determined from the plastic material manufactured premolding. An independent claim is included for a device for manufacturing plastic containers.

Description

The The present invention relates to a device and a Method for producing plastic containers. From the state of the art Such devices and methods are known. It will be first with the help of an injection molding machine Plastic preforms produced. These plastic preforms usually have one body and a arranged on this body Thread on. This thread is usually already in his final form in front. The main body In contrast, it is expanded by an expansion process to the plastic container to be produced. It is common that the plastic preforms before the actual expansion process heated with a heater become.

In younger Time has passed to the, the Plastic for to produce the preforms from recycled material or recycled material. A problem with the use Recylcing Resins is the stretch blow molding operation a higher one Effort must operate in the machine operation, as there are batch fluctuations gives. In other words, the plastic material is for production of preforms are not exactly uniform and thus are the plastic preforms formed therefrom not exactly uniform. Stirring such batch fluctuations from the different raw materials used in recycling, on the also the Recyklat manufacturer has no influence.

By these different mixtures come to different and thus also fluctuating behavior of the preforms (preforms) in the heat absorption.

These Cause fluctuations in turn, to fluctuations in the achieved preform temperature in the Heating of the blower and therefore ultimately lead to more Operator interventions, with very well-trained staff necessary is. Also, the loss of whole batches may occur as these too unevenly shaped for example, because they have not heated enough.

Of the The present invention is therefore based on the object such Irregularities too recognize and, where appropriate, respond to these inequalities. This is inventively Methods and apparatus according to the independent claims achieved. Advantageous embodiments and further developments are the subject of the dependent claims.

at the method according to the invention for the manufacture of plastic containers be plastic preforms by an injection molding process or a melt compression process made of a plastic material. According to the invention is a Infrared absorption of at least a portion of the plastic material definitely and at least one for issued this infrared absorption characteristic value for the plastic material.

As mentioned above, Due to the fluctuating plastics it also fluctuates heat absorption in the PET preform. This in turn is due to a different one Infrared (IR) absorption behavior. The cause of this is that different proportions of infrared absorber material from the raw material producers were used. The present invention is a control the infrared absorption and the infrared absorption behavior possible in this way the production of the plastic container or to influence the plastic preforms. Preferably is the infrared absorption of at least one plastic preform determined after its production.

there It is noted that the infrared absorption behavior is non-destructive can be measured. For this purpose, preference is given to an infrared absorption spectrometer used, which screens a PET sample in principle and the incoming infrared spectrum evaluates.

Advantageous becomes the plastic material in the manufacture of the plastic preforms Infrared absorption material attached. This means that when making the plastic with a material is enriched, in particular for the absorption of infrared Radiation or heat radiation suitable is. These may be, for example, soot particles or the like. Preferably, the amount of the attached absorbent material becomes dependent on from that for influences the infrared absorption characteristic value.

So is it possible, for example, that in response to a measurement signal indicating too low an infrared absorption value, the enrichment with the infrared absorption material is increased. By this enrichment in turn becomes the absorption coefficient of the containers elevated and thus their warming by heat radiation improved. Advantageously, a pump which is the plastic material supplying the infrared absorbing material, depending on the measured Infrared absorption controlled.

Preferably, the above-mentioned measurement is already applied in the production of the preforms, and thus a presorting is different ner absorption goods possible. It would thus be possible later to assign different types of preforms to the blowing process, whereby these different types of preforms are heated in different ways in order to compensate for the different infrared absorption behavior in this way. If a similar absorption class is used in each case, the fluctuations described above can be minimized in this way.

So is it possible, for example, in a aftercooling station an injection molding machine To install a device for measuring the infrared absorption. This measuring device determines, for example, on the basis of a preform per batch or shot the infrared absorption and compares them with a stored database. This is the infrared absorption class of the tested Preform determined. The whole shot or the entire batch will over a switch into a box corresponding to an absorption class or a corresponding container directed. Thus, the preforms produced here are preferably in dependence from the measured infrared absorption of different groups assigned or sorted by plastic preforms.

The Influence on the amount of absorbent material attached during injection molding can by feedback be derived from an online infrared absorption measurement.

The The present invention is further directed to a method of manufacture of plastic containers directed, wherein the plastic preforms by means of a heating device, through which they are preferably transported, heated and subsequently the heated ones Plastic preforms to plastic containers to be expanded. According to the invention is a Infrared absorbance determined at least a portion of the plastic preforms and at least one for this infrared absorption characteristic value for the material output.

In order to an infrared absorption coefficient is also determined in this procedure according to the invention, this infrared absorption is, however, determined in those procedural steps in which the preform is expanded to a plastic container. there It is noted that the production of plastic preforms and molding the plastic containers from the plastic preforms usually not made by the same machines, but partly in completely different time periods and even different Places performed become.

Preferably The infrared absorption coefficient is determined by means of a transmitted light method certainly. This method is particularly suitable since it is the one to be investigated Preform not destroyed. Preference is given to determine the infrared absorption behavior, the transmission of the container for on it irradiated infrared radiation determined.

at Another preferred method would also be possible, the through the containers passing infrared radiation spatially resolved to determine such a statement about a uniformity to be able to meet the material distribution.

at this method according to the invention so that the measurement is preferably made before a blow molding machine and particularly preferably the preforms run in a heating section or an oven.

Preferably is used to determine the infrared absorption Light in a wavelength range used between 800 and 1500 nm. By using light in this wavelength range can be in a special favorable To investigate the infrared absorption behavior. there Is it possible, to provide a radiation device which, for example, light in a wavelength range of 1200 nm, so as to reduce the infrared absorption coefficient to eat. It would be but also possible a wavelength spectrum for example, between 800 nm and 1500 nm in the assessment of Absorb on the degree of absorption.

at A further advantageous embodiment becomes characteristic of the infrared absorption coefficient Values compared with values stored in a memory device. In this way it can be checked on the basis of this comparison whether a measured Absorptance differs from a nominal value to this way to be able to intervene appropriately in the process, for example, to the appropriate container to be able to separate out of the manufacturing process.

Preferably The plastic preforms are heated and then closed Kunstsoffbehältnissen expands and the infrared absorption is before heating the Plastic preforms determined.

Plastic preforms are advantageously separated out depending on a certain degree of absorption. If, for example, the infrared absorption measurements come to the conclusion that the absorption coefficient of the preforms is too low, they can be discarded before the actual heating process and, for example, assigned to a different type of preform. In this way, unnecessary energy ver Loss or loss of preforms are avoided in the production process.

at This variant is preferably each individual preform in terms investigated its absorption behavior. In the method described above enough it, in each case a preform from a batch or a shot to investigate a statement about to be able to hit the entire shot, there usually the material composition within a shot as approximately constant can be accepted. However, too several containers from a shot to be examined by appropriate statistical Measures a more accurate statement about the material composition of the shot in question.

at Another advantageous method is using an infrared absorption measurement determines a water content of the preforms. This makes it possible, in addition one Measurement over the water content in the preform by an additional analysis of the "water band" or the perform there absorption. The water content is an important core parameter for the processing of PET and with conventional Methods only very expensive to determine. That's how it is for example, it is possible an additional Provide radiation device, which in the water typical absorption range radiates, for example, a wavelength range between 2000 nm and 7000 nm and preferably a range between 2000 nm and 3000 nm. This measurement of water content could be in the above-mentioned infrared absorption measurement be easily integrated by adding an additional radiation device is provided, which radiates in the range of water absorption.

The The present invention is further directed to an apparatus for manufacturing of plastic containers directed with an injection molding device, which consists of a plastic material Plastic preforms produced. According to the invention, the device has a Infrared absorption examination unit which has an infrared absorption of at least one part of the plastic material. This is also due to the device according to the invention a possibility created to recognize preforms that deviate unfavorably from setpoints to be able to.

Preferably is the Absorptionsuntersuchungseinrichtung downstream of the injection molding apparatus arranged and determines an infrared absorption degree at least a part of the produced plastic preform. That's it also in this embodiment possible, to weed out certain preforms or different classes assigned.

at a further advantageous embodiment, the absorption examination device a radiation device, which light in an infrared Wavelength range on the plastic containers irradiates. By doing so, a non-destructive Investigation of the infrared absorption degree to be made. Can be advantageous also a plurality of radiation devices be provided which light in infrared wavelength ranges on the plastic containers radiate. In this way it is possible to attach the preform to several To investigate bodies, in this way the infrared absorption coefficient also statistically evaluate and to prevent possibly an area with a particularly high infrared absorption degree the Measurement falsified.

at a further advantageous embodiment, the absorption examination device a radiation detecting device, which on the plastic containers irradiated and transmitted by these transmitted light. Basically, one could Measurement be performed with a spectroscope. Spectroscopes are but relatively expensive.

Therefore is it possible, for example, to use two or three diodes as radiation devices, wherein these two or three diodes have a defined spectrum and in each case a suitable recipient of this area. On this way it is possible to prevent the problem of so-called lamp aging of the usual spectrometer.

Besides is the solution in which only two or three diodes are provided, cheaper and faster. Such infrared diodes do not age substantially and keep it long and radiate a well-defined narrow Spectrum range off.

Preferably is the radiation detector device with respect to the examined Opposite preforms the radiation device arranged to pass through the preform to detect and analyze transmitted light.

Furthermore, the absorption examination device preferably has a further radiation device which emits radiation in a wavelength range between 2000 nm and 3000 nm. This further radiation device is used in particular for the investigation of water inclusions or water content in the preforms produced. Preferably, a plurality of such further radiation means are provided, which examine the water content at several areas of the preform. Also by this procedure it is possible, measuring errors by local Avoid maxima in water content.

The The present invention is further directed to an apparatus for manufacturing of plastic containers directed, this device having a heating unit, which Heated plastic preforms and a to this heating unit subsequent Expanding device, which are the heated of plastic preforms to plastic containers expanded. According to the invention the device comprises an absorption examination device, which an infrared absorptance of at least a portion of the plastic preform certainly. Preferably, the device is in the manner described above Art designed. Preferably, the absorption examiner is upstream in terms of the heating device arranged. In a further advantageous embodiment a transport device is provided, which the containers through the heating unit through promoted or conveyed past heating elements.

Further Advantages and embodiments emerge from the attached Drawings:

In this demonstrate:

1 an inventive device for producing plastic containers;

2 a recorded infrared absorption spectrum of a container;

3 an illustration of the arrangement of an infrared absorption examination device, and

4 another view illustrating the arrangement of an infrared absorption examination device.

1 shows a device according to the invention 30 for the manufacture of containers. There is a sorting device 31 provided which the incoming preforms 10 in a specific orientation. Subsequently, these preforms 10 a transport device 32 as fed to a chute, along which they become a single-ended star 36 be guided. At this single-star 36 closes a heater 33 on, through which the containers are passed, to subsequently in a blowing device 34 to be expanded to plastic containers.

This blowing device 34 has a variety of treatment stations 35 on, in which the preforms 10 to be expanded to containers. Upstream of the heater 33 an infrared absorption examination device is provided, which in its entirety by the reference numeral 6 is marked.

In this embodiment, this infrared absorption device has 6 a variety of radiation devices 11 . 12 on which through the containers 10 through to sensor devices or radiation detector devices 14 . 16 . 18 radiate. These sensor devices 14 . 16 . 18 thus measure the radiation transmitted through the containers and in this way determine the degree of absorption of the individual containers. The reference number 3 refers to a discharge device with which individual containers can be discarded from the device, for example containers which have too low an infrared absorption coefficient.

It would also be possible, the Ausschleuseeinrichtung 3 downstream with respect to the heater 33 to arrange. It is possible that the discharge device is coupled to the infrared absorption device to selectively eject containers with too low an infrared absorption.

2 shows an example of a recorded infrared absorption spectrum of a container examined. It can be seen here that in a wavelength range between 700 and 1500 nm, a high proportion of the infrared power is transmitted. For example, it would be possible to do that in 2 stored spectrum as a reference and to compare with recorded infrared absorption data. If, for example, certain containers have a significantly higher transmission, the opposite can be concluded with a low infrared absorption. In this case, the containers could be assigned to another class of containers.

In this way, as stated above, it is possible to form different classes or groups of containers, wherein in the manufacture of the plastic containers the heating device 33 each could be adapted to these different classes and different classes of containers treated differently or heated differently. Also, it would be possible to change the parameters of the expansion device 34 to adapt to the different classes of containers.

3 shows a schematic representation illustrating an infrared absorption measurement. Here are three superimposed radiation devices 11 . 12 . 13 each showing infrared light on a container 10 more precisely, a basic body 10a this container 10 radiate. This light is at least partially transmitted from the container and gets on the beam lung detector devices 14 . 16 . 18 , The sensor wavelengths are based on the wavelengths of the radiation devices 11 . 12 . 13 customized. Above a support ring 10b ie at the level of the thread 10c Preferably no infrared absorption investigation facilities are provided, since in this area no expansion of the containers 10 takes place.

The three radiation devices 11 . 12 . 13 can radiate different wavelength ranges, for example, the upper radiation means a wavelength in the range of 800 nm, the average radiation means a wavelength in the range of 1200 nm and the third radiation means a wavelength in the range of 2500 nm. Thus, the third radiation means is suitable 13 in particular for determining a water content within the preform 10 , However, the wavelengths of the third radiation device could also be significantly higher, for example in a range between 6000 nm and 7000 nm, in order to investigate the presence of water.

4 shows a further embodiment of an absorption device according to the invention. Here it is in its entirety with 10 designated container along the transport direction T at three radiation devices 11 . 12 . 13 past. These three radiation devices 12 are in 4 arranged in front of the container. Behind the container are already in 3 described radiation detector devices 14 . 16 . 18 , each one of the individual radiation devices 12 assigned. However, it could also find a continuous radiation detector device application. Instead of in 4 It would also be possible to provide a spectrometer for investigating infrared absorption.

All Features disclosed in the application documents are considered to be essential to the invention as long as they are individually or in combination with respect to State of the art are new.

Claims (19)

A method for producing plastic containers, wherein plastic preforms are made by injection molding of a plastic material, characterized in that an infrared absorption of at least a portion of the plastic material is determined and at least one characteristic of this infrared absorption of the plastic material value is output. Method according to claim 1, characterized in that that the infrared absorption of at least one plastic preform is determined after its production. Method according to at least one of the preceding claims, characterized in that in the manufacture of the plastic preforms the Plastic material is attached to infrared absorbent material. Method according to claim 3, characterized that the amount of attached Infrared absorption material as a function of that for the infrared absorption characteristic value is influenced. Method according to at least one of the preceding Claims, characterized in that the produced plastic preforms dependent on from the measured infrared absorption of different groups be assigned by plastic preforms. Method for producing plastic containers, wherein plastic preforms are heated by means of a heating device and subsequently the heated ones Plastic preforms are expanded to plastic containers, characterized in that an infrared absorption degree at least a range of plastic preforms is determined and at least one for this infrared absorption coefficient characteristic value for the plastic preform is issued. Method according to at least one of the preceding Claims, characterized in that the infrared absorption by means of a transmitted light method is determined. Method according to at least one of the preceding Claims, characterized in that for determining the infrared absorption degree Light in a wavelength range between 800 nm and 1500 nm is used. Method according to at least one of the preceding Claims, characterized in that the for the infrared absorption degree characteristic values with stored in a memory device Values is compared. Method according to at least one of the preceding Claims, characterized in that the plastic preforms are heated and then to plastic containers be expanded and the infrared absorption before heating the Plastic preforms is determined. Method according to at least one of the preceding claims 6-10, characterized in that plastic preforms depending on be discarded the specific degree of absorption. Method according to at least one of the preceding Claims, characterized in that with an infrared absorption measurement a water content of the preforms is determined. Device for producing plastic containers with an injection molding device which produces plastic preforms from a plastic material, characterized in that the device comprises an absorption examination device ( 6 ), which determines an infrared absorption of at least a portion of the plastic material. Apparatus according to claim 12, characterized in that the absorption examination device ( 6 ) is arranged downstream relative to the injection molding apparatus and has an infrared absorption coefficient of at least a portion of the produced plastic preforms ( 10 ) certainly. Device according to at least one of the preceding claims, characterized in that the absorption test device ( 6 ) a radiation device ( 11 . 12 ), which irradiates light in an infrared wavelength range on the plastic containers. Device according to claim 14, characterized in that the absorption test device ( 6 ) a radiation detector device ( 14 . 16 . 18 ), which on the plastic containers ( 10 ) and irradiated by these transmitted light detected. Device according to at least one of the preceding claims, characterized in that the absorption test device ( 6 ) a further radiation device ( 13 ), which emits radiation in a wavelength range between 2000 nm and 7000 nm. Contraption ( 30 ) for producing plastic containers with a heating unit ( 33 ), which heats plastic preforms and a to the heating unit ( 33 ) subsequent expansion device ( 34 ), which the heated plastic preforms ( 10 ) expands to plastic containers, characterized in that the device ( 30 ) an absorption examination device ( 6 ) which has an infrared absorption coefficient of at least part of the plastic preform ( 10 ) certainly. Contraption ( 30 ) according to claim 18, characterized in that the absorption test device ( 6 ) according to at least one of the preceding claims 13-17 is executed.