Problems Needing Attention in Printing and Coating Aluminum Foil


1Problem raised

In recent years, the quality of pharmaceutical PTP aluminum foil packaging has been continuously improved, and the scope of application has also been expanding. Applications such as food packaging and health product packaging have been applied. However, some problems appeared in the process of printing and coating PTP aluminum foil, which caused different degrees of losses and caused adverse effects. In order to improve the quality of aluminum foil printing and its use, this paper chose most users to feedback quality problems, and summarized several common frequency High-level, large-impact, and urgently needed to be solved together with colleagues to discuss, the purpose is to make the use of aluminum foil packaging machinery managers can better deal with the resulting quality problems.

2 concept of medicinal aluminum foil

The metal foils used in pharmaceutical packaging applications are aluminum foils, which are called aluminum foils for pharmaceutical packaging (commonly known as PTP aluminum foils). PTP aluminum foils are printed in the English Press Through Packaging. The more formal name in the industry is aluminum foil for pharmaceutical packaging. There are also aluminum foils called blister packs. China's title for the use of PTP aluminum foil in pharmaceutical packaging materials and container registration certificates: PTP aluminum foil for pharmaceutical packaging.

One of the main raw materials for the production of PTP aluminum foil is industrial hard pure aluminum foil, which is customarily called "original aluminum foil" or original foil in the pharmaceutical packaging material industry. When used as a pharmaceutical packaging material, aluminum foil is the only metal material in the packaging material. Aluminum foil has: (1) non-toxic, odorless; (2) excellent electrical conductivity and shading; (3) extremely high moisture resistance, gas barrier and taste protection, can be the most effective protection of the packaged material. Therefore, it is a kind of packaging material that has not been replaced so far. No matter what kind of vapor-deposited metal film or coated special film can not completely replace the aluminum foil. In the field of modern packaging and decorating, almost all composite flexible packaging materials that need to be opaque or high barrier use aluminum foil as the barrier layer. Since aluminum foil has both the above advantages, light weight, and a certain degree of strength and printability, it can also print a variety of text or patterns on it. When it is made into a blister pack, it can be crushed with a little pressure when it is used, and it is convenient for the patient to take medicine and carry it conveniently.

3 common quality problems of aluminum foil printing and coating

In the process of printing aluminum foil, there are often some quality problems, summed up with the following common defects.

3.1 Aluminium Foil Print Quality Fails to Meet Standard Requirements

The common problems that do not meet the standard requirements for printing quality are: unclear printing, misplaced printing, especially overprinted aluminum foil.

3.1.1 printing font is fuzzy

Causes: (1) ink viscosity is too low; (2) scraper has a wavy deformation; (3) the angle of the blade to the plate cylinder is not appropriate; (4) the tension of the aluminum foil is not adjusted well; (5) the ink dries too slowly (6) The operating speed is not coordinated. Control and improvement methods: According to the above issues to be specific treatment: (1) increase the viscosity of the ink; (2) straighten or renew the scraper as much as possible; (3) adjust the angle of the scraper and the entire line of the scraper; (4) adjust or confirm Tension; (5) Change to quick-drying solvent and increase heat to increase the drying speed; (6) Check whether the printing roller and aluminum foil run at the same speed.

3.1.2 overprinting aluminum foil font dislocation

The reason: Due to overprinting, there are many plates for printing, and there are many influencing factors. (1) The reason of the equipment, in the long-term production process, some of the main components of the equipment are worn, such as the bending of the printing shaft, the shaft sleeve is not refueled causing wear, and the uneven drawing roller will cause misplacement of the font in overprinting; (2) printing plate The misalignment pressure of the rollers, the uneven pressure at the left and right ends of the plate roller, the looseness of the printing roller and other factors cause misprints and font misalignment; (3) Problems in process technology, unbalanced control of unwinding and winding tension of raw materials, Operational errors, improper blowing heat, misalignment, etc. affect the misplacement of overprinted typefaces; (4) Disadvantages of overprinting fonts (over normal error range) caused misalignment of overprinted typefaces; (5) Ink viscosity is high, influence overprinting is not allowed, fonts Dislocation; (6) The change in the properties of the aluminum foil raw material (heavy book thickness) affects the constant tension and causes misplaced characters.

Solution: (1) The equipment should establish a circuit inspection system and refuel the operating system on a regular basis. The worn equipment parts should be replaced regularly, and the record of replacement date should be established in order to find out; (2) The post-operation method should be established in the process technology, and the opening and closing tension values, and the blowing hot air temperature, air volume, and blowing time needed during operation should be established. And detected by the operator on time. And there are inspection records; (3) plate-making to meet the actual sample provided by the user and control overprinting drum actual proofing, meet the requirements by the quality inspectors signed qualified before being put into production; (4) ink viscosity according to climate temperature changes, with The viscometer is adjusted at any time; (5) The performance of the original aluminum foil changes greatly, and it is necessary to coordinate the exchange of raw materials.

3.2 The ink color is different

In general, the color of the aluminum foil produced for the first time will have a slight color difference with the reference sample, mostly due to the difference in ink material or substrate. It can be confirmed by the buyer at the supplier's site when necessary, and it must be strictly controlled as a production printing process.

3.2.1 The color is too light

(1) The concentration of printing color in the same batch is insufficient: Causes: 1) Too much solvent in ink; 2) Ink precipitation; 3) Intaglio engraving is too light. Solution: 1) Add new ink, adjust the ink to an appropriate viscosity; 2) Mix the ink thoroughly before putting it in the ink tray, and warm it up in the winter in winter.

(2) The printing color of the same batch is too dark: Causes: 1) The viscosity of the ink is too large; 2) The ink concentration is too large; 3) The gravure engraving is too deep or damaged. Solution: 1) Add a specified amount of solvent to the ink, adjust the ink to an appropriate viscosity, 2) add a diluent, and 3) recreate the gravure cylinder or fill the dent.

3.3 Printing foils wrinkle

There are many reasons for wrinkling. There are wrinkles in the printing process, aluminum foil in raw materials, wrinkles in improperly adjusted pharmaceutical packaging equipment, and wrinkles in aluminum foil heat sealing materials. Only the wrinkles appearing in the printing process are analyzed below.

The causes of wrinkles during the printing process are: (1) the edge of the aluminum foil material is loose; (2) the central part of the material is slack; (3) the printing tension is not proper, or the substrate itself has wrinkles;

(4) The angle at which the aluminum foil is wound around the guide roller or the rubber roller is too large; (5) The hardness of the rubber roller is insufficient; (6) The machine or the roller and the guide roller are improperly arranged.

Wrinkle solutions during the printing process: (1) Use of eccentric drum shafts; (2) Use of bow rollers, tension adjustment rollers; (3) Proper adjustment of tension; (4) Adjustment of the aluminum foil winding angle; (5) Use of high hardness Rubber roller; (6) Study the assembly position of the machine and the roller.

3.4 Seriously affect the quality of drug packaging

3.4.1 Printed Substrate Aluminium Foil Excessive Pore Size

According to the provisions of GB12255-1990: "PTP aluminum foil pinhole diameter greater than 0.3mm can not have, diameter of 0.1 ~ 0.3mm per square meter can not be more than one." PTP aluminum foil pinholes are due to penetrability defects, affect the barrier properties of aluminum foil (gas barrier, moisture barrier, light blocking), so that the packaged drugs are affected by oxygen, water vapor or light to reduce efficacy, when severe Even deterioration can not be used. Since the water vapor transmission rate and the oxygen transmission rate are important indicators of aluminum foil as a packaging material, the specified value is generally low. At the same time, the aluminum foil itself, especially aluminum foil having a thickness of 0.02 mm or less, is apt to be wrinkled, easily cracked, and easy to generate pinholes. Therefore, the detection of the water vapor transmission rate and the oxygen permeation amount of the pure aluminum foil is difficult, and the dispersibility of the test data is large.

The pinhole of the aluminum foil is the only factor that causes the aluminum foil to produce the permeability. In general practical application, only checking the size and the quantity of the pinhole of the aluminum foil can explain the problem. According to relevant research, the gas permeability of pure aluminum foil is directly proportional to the concentration difference of gas. When the pinhole radius of aluminum foil is greater than the thickness of aluminum foil, it is proportional to the size of pinhole radius. Therefore, before the printing of aluminum foil, the quality of the original aluminum foil should be inspected, and in particular, the original aluminum foil should be sampled for pinhole degree, tear strength, and tensile strength. At present, China's aluminum foil manufacturers have reached the national standard for aluminum foil pinhole requirements and can guarantee stable quality, but some of the few PTP aluminum foil manufacturers often simply to reduce costs, to seize the market at low prices, often using some unqualified original aluminum foil, so that Pinhole degree exceeded. In addition, there are many crystal spots on the surface of aluminum foil, and there are many oil stains on the surface. The original aluminum foil has many phenomena such as wrinkles, indentations, and stripes. This not only affects the printing quality of characters and patterns, but also affects the coating quality of protective agents and adhesives, thereby affecting the pharmaceutical packaging. Sealing performance.

A simple way to determine the size of the pinhole is to take a piece of the original aluminum foil and observe the presence or absence of pinhole light leakage. Specially used to detect the pinhole degree of aluminum foil, use the detection device as the pinhole table, use the wooden box of 800mm×600mm×300mm or the appropriate volume, install the 30W fluorescent lamp inside the wooden box, place a glass plate on the wooden box, and the glass plate is lined with black paper and leave There is a 400mm x 250mm space to check the pinhole of the sample. Take 200 pieces of 400mm x 250mm samples in the finished product of aluminum foil and place them one by one on the pinhole inspection table. Check the pinholes in the dark place. The requirements for the pinholes of the aluminum foil are: (1) There should be no dense and continuous , Periodic pinholes; (2) can not have a pinhole diameter greater than 0.3mm, pinhole diameter of 0.1 ~ 0.3mm per square meter can not be more than one. The pinhole degree of aluminum foil is a very important technical indicator for the inspection of PTP aluminum foil. It will be related to the sealing performance of packaging medicines, so it is necessary to pay great attention to this inspection.

3.4.2 Finished protective layer after printing

According to the process requirements, after the aluminum foil printing, the surface needs to be coated with a protective agent for protecting the printed text pattern. Of course, the protective layer also has the function of preventing the aluminum foil from contacting with the adhesive of the inner layer during winding to cause the drug to be contaminated. , It can also prevent the self-oxidation and deterioration of the surface of the aluminum foil and prevent the abrasion and peeling of the ink layer on the surface of the aluminum foil, and at the same time, it also improves the heat resistance when the bubble cap is pressed. Some manufacturers reduce the cost, cut corners, and do not apply protective agents. As a result, drug manufacturers often find that printed text patterns are blurred when they are heat-sealed, and they are easy to deink and cause losses.

In fact, the user can easily determine whether the aluminum foil is coated with a protective layer before use. The method is: cutting an aluminum foil, and then using a lighter to grill the protective layer for a few minutes, if it is found that there is no change in the surface of the protective layer or black smoke stains, once Wipe off, that is, unqualified aluminum foil products without a protective layer; if it is found that the protection layer turns yellow and appears like a halo-like pattern, it won't fall off after wiping, that is, a product coated with a protective layer. However, in order to ensure the use of quality, the best way is to use a heat sealer to detect the heat resistance of the protective layer, the heat resistance of the protective layer is good or bad to determine whether the PTP aluminum foil in the packaging of drugs when the packaging machine heat roller (version) is correct Aluminum foil surface damage caused by graphics. During the test, a 2kg pressure heat sealer was used to apply heat and pressure at 200°C for 1 second to the graphic surface of the aluminum foil to observe whether the printed image was clearly peeled off.

3.4.3 aluminum foil coating adhesive non-uniform aluminum foil printing surface protection agent, and the other side of the adhesive, adhesive coating is uniform, with or without coating will directly affect the blister packaging quality, That is, the sealing performance.

Simple discrimination method: In the place with sufficient light, observe with the naked eye, if there is a clear linear straight line, or a very short intermittent or uninterrupted straight line, it is an unqualified product. The adhesive layer of the qualified product should be very smooth and flawless. Detection and quantification method: Analyze the balance with one ten-thousandth, take 5 pieces of 100mm×100mm sample in the finished product, weigh them respectively, and wipe off the adhesive with ethyl acetate, butanone or other solvents, and weigh; The difference between the two masses is the coating amount, and the average value of 5 coating amounts is determined. The difference between the coating amount and the average value of each sheet should be no more than ±12.5%.

In addition, the thickness of the adhesive layer has a great influence on the firmness of the adhesive, and the adhesive layer is too thin. When the hard PVC sheet is hot-pressed, the adhesive fastness may be reduced due to lack of material. A heat sealer is used to detect the heat seal strength of the adhesive layer to determine whether it meets the quality requirements. When testing, a square with 100mm is die-cut, and a pressure of 2kg and a temperature of 150°C are used to seal the aluminum foil and other sizes. PVC sheet heat seal 1s. Then use a 15mm special die cutter to cut into 15mm strips. Placed on a tensile tester to measure the pull force is the heat seal strength. The heat-sealing strength of aluminum foil adhesive layer and PVC should be ≥7.0N/15mm.

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