MX2013008241A - Laser micro-perforation device for polyamide films for a packing process performed under a modified atmosphere. - Google Patents

Abstract

The present invention consists in a laser microperforation device used for perforating different linear patterns with micrometric sizes in polyamide or nylon bags used as packing for fruits and vegetables (products), which control the atmosphere thereof when these are under controlled refrigeration conditions. The laser system is able to perform perforations of different diameters, and arrange them in different positions lengthwise a linear working area, the system being assisted by a ceramic of high thermal conduction, which accumulates heat for an instant due to the contact with the laser energy, when this ceramic is brought into contact with the bag, for a predetermined time, this may transfer the heat and change the states of the matter of the bag from solid to vapor or gas. The packing with microperforations is useful for promoting and extending the shelf life of the aforesaid food products, upon controlling the values and rates of transmission or breath of O2, CO2 and ethylene p roduced in the periods of post-harvest and final consumption.

Description

LASER MICRO-PERFORMANCE DEVICE FOR POLYAMIDE FILMS FOR A PROCESS OF PACKAGING UNDER MODIFIED ATMOSPHERE DESCRIPTION OBJECT OF THE INVENTION The present invention consists in a laser microperforation device that is used to perforate different linear patterns with micrometric sizes in bags of polyamides used as packages for whole fruits and vegetables (products) and thus have a package that controls its atmosphere when it is Find under controlled cooling conditions. Achieving with this combination, a packaging process that will have an atmosphere modified MAP ("Modified Atmosphere Packaging") and controlled CAP ("Controlled Atmosphere Packaging"). The laser system has the capacity to make perforations of different diameters, and to be able to locate them in different positions along a linear work area. This process will allow the packaging to be used in the distribution part, in the storage part and in all the cooling stages of several whole vegetables. Thus, by means of micro-perforations, the shelf life of these food products is promoted and extended, by controlling the values or rates of transmission or respiration of 02, C02, and ethylene produced in the periods included since the post-harvest period. harvest of the product until its final consumption.

BACKGROUND Fresh food products are very susceptible to invading pathological organisms in the post-harvest period, due to the increase in respiration they have after they are harvested. However, the respiration of these fresh fruits and vegetables can be reduced by many preservation techniques such as low temperatures, canning, dehydration, dry frozen, atmospheric barometric control, etc. Packaging processes with controlled atmosphere is the common name and used to minimize the processes of fruits and vegetables including fresh vegetables ready to eat. This includes, an investigation of the respiration rates that are given by the production and exchange of oxygen, carbon dioxide, or nitrogen or ethylene. The recommended percentages of oxygen in an atmosphere Modified for fruits and vegetables to have safety and quality are between 1% and 5%. Although other gases such as oxides, sulfides, ethylene, chlorides, as well as ozone, or propylenes should be well researched and taken into account, depending on the product to be protected. With this basically seeks to have a successful control between the respiration of the product and the production of ethylene, in this process and indisputable temperature control will be consistent with the fruit or vegetable to be conserved. Packing processes with controlled atmosphere seek to modify the surrounding air in the food or product and constantly change it with another. Among the important factors of this atmosphere movement are found in the moving compounds of 02, C02, and C2H4.

It is known that for the food consumption industry, the packaging part of fruits and vegetables is crucial, and having well controlled the storage refrigeration temperature and / or the atmospheric conditions within the packaging are the most important factors to maintain a fresh and extended product in your life. of shelf.

This interest, adds to the global effort, which has been detected by the changes in eating habits, where we now have a society that is greatly exceeded in its body weight. And as an answer to diminish this problem, propaganda is invited or distributed so that there is greater consumption of fruits and / or vegetables. But this means that the consumer at the end of this effort should be offered and given a product that stays fresh, and with a very good view. However, already in the reality of a post-harvest process and consumer, it is necessary that the points of agricultural production of these are far from the points of sale to the consumer. It is therefore, that the transportation that is typically by sea or land requires several days of transfer from the producer to the client and therefore, those days are enough to deteriorate and the product after those days lacks of a visual impact of sale for a very demanding consumer.

In the state of art, it is necessary that the packaging used for the transportation by sea or land of exotic or other fruits, are made with a controllable atmosphere through micro perforations in the bags, in such a way that the fruit or vegetable breathes in a controlled way and thus lengthens shelf life and storage. It is said that the carbon dioxide lasers that are used to perform such a function, these systems apart from being very voluminous, that of being very complex, with many pieces and with limited work areas. Unquestionably, the technology of the industry of transformation and the use of lasers have benefited all systems of this type, counting on companies with years of experience in the subject and improving day to day their systems that already have point of sale. However, it has not touched other areas of material-laser interaction. And basically we refer to those that enter the near infrared region, where lasers such as Nd-YAG, or solid-state laser diodes within the visible, have not been attractive to this market. Since as characteristic of these lasers, and with the abundant material of packaging that are plastics or nylon, there is very little interaction between their molecules and optical radiation such as reflection are low; very high transmission, and its absorbency is almost zero. But in all this industrial career, assisted assistance to the interaction laser-matter has taken an improper turn with the incorporation of a premixing of inks or pigmentations in the process of manufacturing bags for packaging, however, this generates an excessive increase in The cost of the final packaging product. An inexpensive option is the one with hot pin-hot or micro-needle systems that are implemented in a rotating drum and are aligned and synchronized to the cell or manufacturing line of a bolster and with their natural movement they get in touch with the bag and perform the micro perforations, however the quality of them is very low and even in a good percentage of these is not even drilling because the raw material is an extensible and flexible product and in many cases manages to overcome or dodge the action of a hot needle in physical contact with the bag.

On the other hand, the fresh fruit distribution industry has increased its market to one that oscillates in several billions of dollars, and that is where the need to use MAP processes ("Modified Atmosphere Packaging") / CAP ("Controlled Atmosphere Packaging" ) play important roles.

Modification of the atmosphere, which takes place in the packaging can be dependent on variables such as the permeability of the packaging material, the respiration rate of the protected product, and the temperature during the distribution and storage. Currently, these techniques which modify or control the atmosphere within the packages containing products are well known. These atmosphere controlled devices use regimes similar to the storage atmosphere controls. Unfortunately, the regimes do not provide an optimum atmospheric condition within the package for the products during distribution or storage, which can result in premature fermentation of the product.

Premature fermentation can result in reduced shelf-life of food products, which in turn can result in lower product sales. In this type of products another technological point is the effective sealing in the bag, since between the perforations, the permeability of the film and the residual space in the seal, there is a quantity of gas diffusion that must be considered at the total time of interaction from the outside to the interior of the bag that can be made of polyethylene, polypropylene, PVC. The breathing reason also considers properties of the films used and through studies that reveal how carbon production is and oxygen consumption relates to a whole vegetable, to its stages that it experiences its maturity, the quantity also in the package; and this breathing reason are also modified with the temperature controlled all these important data to be taken into account and are required to have a balanced number of micro perforations and for which this invention only suggests it to be taken into account. Not forgetting, external environmental factors such as temperature, relative humidity and the speed of air to which they can affect the permeability of the bag, causing an increase or reduction of oxygen or carbon dioxide levels. Since in the maturation process the ethylene production inside the packages increases the putrefaction process of the whole fruits or vegetables.

Throughout this process of extending the shelf life of fruits, vegetables, etc., it has demanded that we have controlled refrigeration systems, and that we can produce containers that allow the respiration of the gases that are produced by the time these products are kept waiting on arrival that will have the final consumers, and that the mobility process that they have on ships, trains, or aircraft, requires an investigation so that through quantification processes in which rate values in the exit and in the entrance of gases can be handled and be the most adequate to extend the period of decomposition of these products. For example, in patent US7866256, a device in whose invention describes an apparatus for controlling the composition of gases inside a cargo container, and where by sensors and controllers are put to the task that at least one gas passing through of a membrane can be determined a strict control and with this have the different ratios of controlled entry and exit. On the other hand, patent US6730874, describes a more direct way of controlling the flow of the production of ethylene, carbon dioxide, oxygen, and gases that tend to be generated or expelled at the moment in which a fruit, vegetable or meat is stored and within the times of the post-harvest process to that of the delivery to the end users. In this case, and by means of micro perforations made with lasers in bags, and that once the product is packaged, the entrance / exit of these gases can be controlled and thus lengthen the shelf life of the product, in this device, a laser is used carbon dioxide that concentrates all its energy in the raw material that is a bag and drills, this system is the most dominant in the market of micro perforated bags, however, the quality of the perforations, even when the realization is guaranteed of them is not completely controlled, since having for some reason or other folds or wrinkles in the bag to be drilled, the excess heat generated by the laser causes several layers of these bags to merge and when separating or opening the bag to put the product, it is torn and even when this technique works with tables that relate the product with the number of perforations with a certain diameter and in this way they control the breathing reason, this tear Adura in the same bag means that in a large part of the bags they present a considerable amount of inconsistency in the total area sought, which by studies predict that they can guarantee the extension of shelf life.

However, the two most important companies in the world continue with the task of improving their processes with these carbon dioxide lasers and they strongly attack the details that are found day by day in an industrial process. The demand for them continues to grow and what has been implemented to mitigate these problems, undesirably increases the costs of these equipment and increases the production of micro-perforated bags and is a very exclusive product for large companies and not of an acceptable scope for other types of companies with low sales volumes of micro-perforated bags.

Another detail detected in these laser products for micro, perforations is that they have basically been developed for fruits and vegetables cut or segmented mainly, and very few are for completely whole vegetables. These techniques have been implemented with carbon dioxide lasers as the energy that can interact with plastic bags or polyamides, and that by placing them in the value chain of cells or manufacturing lines of industrial bolseadoras it is possible to drill in a variety of sizes and in the line of the industrial system. However, when it comes to whole vegetables, the needs of micro perforations and the degree of permeability of the bags that are available, the part that yields in diameters is required to be several micrometers in diameter. Leaving an area of opportunity to develop devices to cover this market also very large.

The process of interaction matter-laser is a subject of global importance, because with this has grown a lot the different industrial markets and especially those of the transformation. The acronym that has the LASER device of its abbreviations in English "Light Amplification by Stimulated Emission of Radiation" is a process whereby the stimulated emission can generate a beam of coherent light, high concentrated energy, directional, and although his theory was known from the beginning of 1900, it was until the 60's that experimentally proved its applicability with the first experiment conducted by Charles Townes, with a device that by the principles or physical bases that were postulated at the beginning of all this built an optical MASER, and from there, the race to know more about this invention arose branches of its type, its size and its physical properties. In general, we are talking about an invention that consists of an active medium, which is capable of generating the laser, and which has four basic processes that are produced in this generation, and are referred to as pumping, spontaneous emission, emission stimulated and absorption.

Already in the race of the development of the same, a global and standardized classification is imposed as indicated in the document UNE EN60825-1 and classified based in the property of its optical power and its danger, leaving four classes, ranging from class 1 to class 4.

The most attractive thing about the same laser was its ability to give the correct solution to problems, reaching many more fields in daily life, and spectacularly, they have covered many of the industrial processes, health, telecommunications, research, and their benefits have given to have a civilization with more products that come to give more comfort to its existence, and better yet, to participate in medical processes where you can have a laser to improve the ambulatory operations of patients presenting identifiable discomfort in a large branch of health problems (say prostate, open-heart surgery, tattoo removal, elimination of body fat, vision problems, etc.), and the best known is the LASIK process, which allows to alter or remove matter live of the human eye itself and with this give hope to have a better visibility thus finding a niche of opportunity for its use to support the processes of re cataract motion, or correction of the pupils. In the latter with the alteration of the living lens formed by our eye and readjust its position to have diminished the typical problems of myopia, hyperopia, astigmatism, glaucoma, etc., to reduce the use of lenses that apart from being annoying and having a use at all times, an operation on the eyes can recover a patient acceptable visibility for reincorporation to their activities that makes their life itself.

The applications of lasers in the industry have been enhanced by the parallel development of robotics, and computer science, which have made possible the automation of the processes and the precise handling of the beam to take it to the workplace. The current perspectives of application of these systems are aimed at an integration with CAD-CAM systems.

Lasers, therefore, not only in power are classified, but in what wavelength or color they emit, and especially if these are continuous or pulsed type laser signals. In this process, to generate pulsed lasers, a new range of industrial solutions was opened. Among these industrial solutions we can count the interaction of plastics with lasers and thus obtain ablation or evaporate material that we want to remove or that are hindering, and it is there, where the products to modify atmosphere in the process of transporting fruits, vegetables, and meats, and their investigation at the same time to know the reasons or respiration rates of taking out and putting gases for a process deterioration of the product may be delayed and thus allow, that the producers of these foods reach longer distances in kilometers in their export process, of more hours to move their products, and so that their raw materials can reach the table of an end user who will look for it at all times, In this product, you have the closest thing to attractiveness and freshness and have a good texture to the touch, and visual color and smells of fruits or freshly cut products. It is there, where the pulsed laser has allowed to improve this type of industry, since previously, the packing process to lengthen the shelf life of a product was made by a mechanical puncture process with hot micro needles. However, this process simply tears off the raw material of the packaging, and with this we do not have the control of the study that allowed us to know how fast and / or how much gas is required to keep a product fresh.

Depending on the material as it is known, laser drilling is achieved by vaporization, melting, or by a combination of both physical phenomena. Thus, in plastics, the material can be eliminated in the solid state by steam, forming small plastic drops that must be expelled from the microperforation. And with external equipment of blown with compressed air, when arriving at these conditions of fusion of the process laser-matter, to be able to remove this excess of material and to leave free the perforation in the bag. In our technique it is important to emphasize that assisted by a ceramic of high thermal conduction it is possible for an instant to accumulate heat by the contact that is had with the laser energy and when being in physical contact with the bag for the adequate time, to be able to transfer this heat by conduction and get to change the states of the matter of the bag to be solid until it becomes a vapor or gas, which will be removed by a burst of compressed air.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows the isometric view of the laser microperforation device for polyamide films for a modified atmosphere packaging process. Where (1a) is the laser head, (1b) is the PLC programmable logic controller, (1c) is the electric unit, (1d) is the optical unit, (1e) is the pneumatic control unit and (1f) is the control unit of the slider.

A system comprising a laser head (1a) positioned on a one-way slider is observed, which is programmed to slide in a set position that is basically spaced a preferential distance from where a bag seal will occur, and that said head contains all the systems of conductive optical fibers, of the pivots or suction cups for the entry and exit of the vacuum system, and system for opening and closing the existing space where the tubular bag of polyamide will be located; The use of a PLC system (1b) or brain system communicates with a linear slider that based on the size identified by an operator of the bag to be drilled is placed in position to start the microperforation process. In this process, the type of industrial bag is also selected so that the lasers automatically turn on and off in a synchronization process with the natural movement of a tubular bag rewinder that has an industrial bagger and thus, when passing this tubular bag between the teeth of the laser head is open during all this movement and that once detected by the momentary braking system of the industrial bagger, which is communicated to the brain of the system, these teeth of the laser head are manipulated and closed and the focused lasers are placed in their focal lengths suitable to release all the laser radiant energy towards its target which is the plastic or nylon bag or the one in the process and from there, cause instantaneous heat to a ceramic material that is in physical contact with this bag and by driving this acquired radiation is transmitted to the bag or film and thus generate carbonization and evaporation of film material and finally have an acceptable perforation in shape and size. This same system controls in the same way and in synchronized way the shots of the vacuum system.

Figure 2 shows the system of mobility of the laser head to cover different patterns (referenced to the sealing of the tubular bag.) In this case, the physical dimensions are adjusted to be adapted to the jig that is assigned and thus physically embedded to the rungs or bars that has a system of this type.

In Figure 3, subsections (3a) and (3b) show the electronic circuit and distribution of solid state laser diodes energized by controlled current.

The controlling stage of the shots that will be done in the laser is described, first a terminal that is connected to a CMOS which, when fired, will let a current pass and change the impedance properties of the laser feeder module and thus provide the adequate way for an electrical current to reach the terminals of feeding a low-power, low-power laser diode and thus, by means of a high-voltage electronic trip with a very short time, a pulsed signal is built which will allow the laser diode to reach its threshold and emit a high radiation. energy but within a very short period, this can be from a few hundred milliseconds to almost a second of time in the duration of the pulse, which in a natural way and with the interaction of the laser radiation, that of the ceramic conductor of heat and the film to be tested will result in different diameters of perforations. The DSP that is in the brain stage, controls all this electronic logistics and is programmed in such a way that the data handled by the general program already has by default the times and voltages required for a certain dimension in the gaps for a certain number of materials or films that will be tested in this system ..

Figure 4 defines the distribution of the laser tips in the head.

By means of a previous study among the quantity of micro perforations, it was found that there is docuation endorsed of the effective area of the micro perforation, of the position of the same, and especially in the quantity of these holes in the test material or film, of such so that in a linear array of lasers can be produced automatically and depending on the whole plant to work a controlled number of holes that are programmed to a brain or PLC and will control the amount of these and the diameters so that from there can change in a simple program made with these statistical data studied, the number of perforations that this device can perform and ranging from 1 perforation to 10 perforations simultaneously.

Figure 5 shows a vacuum injection system for control of two films (tubular film).

Consisting of a system that is required to ensure good heat transfer that will have a ceramic material of high heat conduction to the film and with this and ensuring full physical contact have a shape and size of perforation in the film, this type of valves Vacuum injectors and their respective suction cups are placed exactly in the positions where the lasers and ceramics are located, and when the laser trigger is activated, these with microseconds of anticipation come into operation and induce vacuum of such magnitude that they guarantee the It is in direct contact with the heat conduction process that is being carried out with the laser shots with its interaction with the ceramic. It is also guaranteed to unroll the bag or raw material since the vacuum area is large enough to stretch the bag and stick it with the minimum wrinkle. By working with a plastic tubular material and with the laser head, this vacuum injection can be achieved by achieving the separation of the bag and in this way guarantee point by point the laser action with the final perforation. The synchronization of input and output of this system are made by the same PLC or brain of the system.

In Figure 6 paragraph (6a) shows the logic applied to the PLC for the entire process and subsection (6b) shows the screen that has the PLC and its selection form which is tactile. This is formed by a man-machine interface developed to directly control using a PLC and its peripheral connections that are the linear slider, the input and output of the laser signals, as well as the input and output of the vacuum action in the bag for separating them and guaranteeing a perforation in a region without wrinkles and avoiding having the two films of the tubular bag and thus preventing melting between the films and consequently a rip in the process of introducing the product into the bag. There are several windows to which a user can access and control with this, the times of shots, the variables for the vacuum system, as well as the linear move of the slider positioner. Also with this system you can access as administrator of the system and vary based on the new characterization of new materials to drill and change the firing times, as well as vacuum input.

DETAILED DESCRIPTION OF THE INVENTION The present invention consists of a laser microperforation device for polyamide or nylon films for a process of packaging under modified atmosphere which is the responsibility of a systematized study of the laser-matter interaction, and the importance lies in that this study demonstrated that of have to include a ceramic high heat conduction that serves as a device for transfer or conduction of laser radiation in the infrared to the polyamide and outstanding data is that only requires low optical powers, the order of a few milli watts and its output in a conductive optical fiber. This translates to requiring low cost laser modules and already within the present invention was impleed a laser point positioning system based on coupling (fusion splicing) all-fiber multiplexing couplers to the output of the laser diodes, which allows to capture an optical power in the single input from the diode and redistribute it equally in several outgoing outputs of the multiplexer, it is so that the deviation and control of the laser power in different points of a marking or perforation line due to this has a low power consumption and requires a single-phase power supply with electric current that does not exceed 50 A. These points are assigned to a laser head Figure (1a) that has prefigured a localizable pattern of tips with fiber optic adapters aligned to simple systems of lenses that focus the optical radiation towards a target which allows its laser-matter interaction to produce from several microns of diameter up to several millimeters, being of a high repetition and of a very acceptable circular quality. This required, the development of a brain control based on a PLC "Programmable Logic Controller" Figure (1b) that allows once selected the pattern of perforations, the turning on and / or off the different external fiber optic ports and by programming in a sequence of times can be synchronized to the rhythm of operation of an industrial bagger of any travel time, tested at the moment and at speeds of 1000mm / sec., In this way, the power to have from three to 10 perforations is simply a matter of selecting through the PLC the routine that will activate the corresponding laser diodes that will have their power switched in time to have a period of on and off according to the mechanical movement of the pocket and so each time the packer stops in a parallel process (say cut of the bag or sealed of the same), the system is triggered and shoot with the predetermined time for the thickness and type of bag that will be of raw material so that this In a synchronized manner, a perforated location can be produced in a linear manner and with this, wait for the next work cycle and repeat the same procedure.

Claims (5)

CLAIMS Having described my invention enough, I consider it as a novelty and therefore claim as my exclusive property, what is contained in the following clauses:

1. A laser microperforation device for polyamide films for a modified atmosphere packaging process, characterized in that it produces micro perforations that depend on the linear optical array added to the final terminals of the optical fibers that conduct laser radiation and that their laser-material interaction can produce from several microns of diameter up to several millimeters, being of a high repetition and of a circular quality very acceptable.

2. A laser microperforation device for polyamide films for a modified atmosphere packaging process characterized in that it adapts to any industrial bagger of any travel time, tested at the moment and at speeds of 1000mm / sec.

3. A laser microperforation device for polyamide films for a packaging process under modified atmosphere, characterized in that it is of low electrical consumption and that it requires a single-phase power supply with electric current not exceeding 50 A.

4. A laser microperforation device for polyamide films for a modified atmosphere packaging process characterized in that it automatically detects the type of bag to be drilled and automatically adjusts its initial and working conditions efficiently.

5. A laser microperforation device for polyamide films for a packaging process under modified atmosphere, characterized in that it can range from 3 to 10 selectable and locatable perforations in a working area relative to that which is present with the bagger. A laser microperforation device for polyamide films for a process of packaging under modified atmosphere characterized in that by means of a ceramic material of high thermal conduction can interact with a laser signal within the region of the near infrared and by conduction transport this heat to the films of polyamides or nylon and thus create a microperforation, preferably when the ceramic and the film is in physical contact. A laser microperforation device for polyamide films for a modified atmosphere packaging process characterized in that it has a vacuum system controlled and with sufficient power to be able to separate a tubular film synchronously and thus obtain microperforation without excessive heat in the ceramic and transmitted The film can be harmful when separating the tubular film and the films can be permanently fused.