Some problems in the detection of composite strength of color printing and packaging

In recent years, many companies have introduced advanced quality inspection equipment while introducing advanced production equipment to monitor product quality. One of the criteria for the detection of product quality is national standards, but its provisions are relatively general and many problems will be encountered in the reference process. On the basis of customer surveys, the author selected some of the representative issues to discuss with the people in the industry.

1. When the composite film is subjected to a T-peel test, the sample to be tested will always be turned upside down or hem. It is difficult to form a right angle by fixing the specimen by hand and moving it with the specimen. In the case of an upturn or a hem, the measured force values ​​are not the same as those measured in the near flank angle. How to measure the peel strength is accurate?

GB/T2791-1995 clearly stipulates that the T-peel test for bonding flexible materials and flexible materials is to apply a peeling force to the adhesive end of the sample, so that the sample will be peeled along the adhesive wire, and the applied force and adhesive wire There can be no control between the angles. That is, the force value is detected in a free state, and it is not necessary to control the angle. Jinan Languang's tensile testing machine has an automatic deheading and tailing function, that is, the force values ​​at the beginning and end of the test are not counted, so the fluctuating effects of the start and end of the test have been eliminated, and the test conditions can be accurately reflected.

2. When the aluminum foil is used as a composite material in a peel test, it is impossible to detect the peel strength because the mechanical properties are very poor and a pull is broken. It is not realistic and accurate to describe the peel strength with no peeling. Although adhesive tapes were sometimes taped to the aluminum foil surface and then sampled for peel testing, the force data displayed was much higher than the untaped samples. How can we accurately reflect the peel strength of aluminum foil composite products?

GB8808-88 clearly stipulates: the plastic composite compounded on plastic or other substrate formed by a variety of soft composite plastics, the principle of which is measured along the length of the sample layer and the substrate pre-skin peeling 50mm stripped part must not have obvious damage . If the specimen is not easy to peel off, one end of the specimen may be immersed in a solvent of about 20 mm until the solvent is completely volatilized, and then the peel test is performed. If this treatment fails to separate from the substrate, the test cannot be performed. This kind of situation can be according to the national standard stipulation draws the conclusion that the test cannot be carried out, explain that the peeling force of the base material and aluminum foil is far greater than its own tearing force. If the company wants to study its peel force, it can be tested after sticking tape on the aluminum foil surface. The results can be used to measure the quality of the composite film.

A large number of studies have shown that the type of substrate has a certain influence on the peel strength. Different types of substrates have different moduli, and the modulus affects the energy required for the deformation of the substrate, thereby affecting the peel strength. The peel strength increases with the thickness of the substrate. Therefore, in discussing the peeling performance of such products, the type and thickness of the substrate, the type and thickness of the tape used, otherwise the test data will lose the reference value.

3. For a three-layer composite structure, such as BOPP/PE/Vm-CPP, when the peel strength of the first layer or the second layer is measured, the other layer is pulled at the same time so that the peel strength between the tested layers is insufficient. Vacuum, accurate, what can be done to avoid this situation? In the detection of three or more layers of complex structure, there is no provision for which layer to start with. What is the sequence?

The national standard does not specify this clearly. Therefore, we must do such experiments. The result is not only the peeling strength but also the phenomena that appear during the test. A large number of tests have shown that the peeling strengths of the conductive layers of the multilayer composite membrane are not the same. There are no relevant regulations in the country. Enterprises can formulate enterprise standard test methods according to their actual conditions. The general principle is that the same sample must not be stripped at the same time for testing, and the peeling of the layered composite film is based on the middle layer.

A case of failure of QZY-1150 hydraulic cutting machine

Once the hydraulic system of the hydraulic paper cutter breaks down, it is generally difficult to find the fault intuitively, which brings certain difficulties to operation and maintenance. Especially for the general maintenance engineer, the knowledge of hydraulic pressure is not enough to eliminate the failure of the hydraulic system. It is even more difficult.

The QZY-1150 hydraulic paper cutting machine used by our company has experienced such a phenomenon in the production: After the paper presser descends and touches the paper product, it pauses for a period of time. The paper cutter starts to descend, and the pressure paper and the paper cutting action are consecutive. Not up. After the cutting is completed, the cutter is normally returned to its original position, and the platen is not lifted, causing great inconvenience to the operation.

After analysis, it is considered that the oil valve is blocked or the direction of the reversing valve is not smooth. We first dismantled the oil valve to clean it and dredge the oil circuit. After the installation, the child's fistula will be collected and the uniform will be collected. W Xing 阜 鲇 鲇 鲇 鲇 鲇 骋墒 骋墒 骋墒 骋墒 骋墒 骋墒 骋墒 骋墒 骋墒 骋墒 骋墒 骋墒 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 椎 幌蚍鸹怠 幌蚍鸹怠 幌蚍鸹怠 幌蚍鸹怠 幌蚍鸹怠 幌蚍鸹怠 幌蚍鸹怠 蚍鸹 蚍鸹? 2) The spring breaks. After removing all other defects, remove the cylinder and find that the return spring of the hydraulic reversing valve is broken and replaced with the same model and the same specifications of the return spring. Then turn on the operation, and the pressure and the paper cutting action are consecutive. Everything returns to normal.

Causes and Remedies of Shrinkage of Printing Film

Shrinkage is a failure caused by bad leveling of the ink film, that is, after the printing, the wet ink film appears during the leveling process, resulting in the exposure of the substrate or the previous color ink layer.

1. Causes of shrinkage

Some people think that the wet ink film can be regarded as two layers up and down, and the cause of the shrinkage hole is that the surface tension of the upper and lower layers of the wet ink film is different. In the film formation process, when the surface tension of the upper layer of the wet ink film is lower than the surface tension of the lower layer, shrinkage cavities occur. In some cases, when the shrinkage of the ink film is about to occur, the loss of fluidity of the wet ink film suppresses the occurrence of shrinkage. However, in some gravure or iron printing operations, as the temperature increases, the wet ink film has fluidity, and secondary shrinkage may occur.

2. Anti-shrinkage measures

In theory, the anti-shrinkage hole will improve the flow and leveling of the wet ink film. On the one hand, the surface tension of the wet ink film is low, on the other hand, it is necessary to have good wettability on the substrate. The specific approach is:

1) Add the leveling agent properly in the ink;

2) Use a low surface tension solvent;

3) Wet the surface of the substrate;

4) Control the ambient temperature and humidity;

5) Select the appropriate diluent;

6) Adjust solvent volatilization speed, reduce ink viscosity, improve fluidity, and extend flow time.

3. Anti-crater

In order to help you properly choose anti-crater agent, briefly introduce all kinds of pore-preventing agents.

1) Solvents: Generally refers to high-boiling mixed solvents. It is both a good solvent and a wetting agent. However, the volatilization of the solvent may cause the solubility of the ink system to deteriorate, resulting in shrinkage, or the ink printing ink in the baking to produce boiling marks, blisters and other ills.

2) Resins: In particular, polyacrylic resins with limited compatibility are preferred. The dosage is: 1%-1.5% of acrylic resin, 0.5%-1% of epoxy resin, and 1% of polyester.

3) Silicone resin: In addition to its anti-shrinkage function, it also has the effect of leveling, anti-floating and defoaming. For example, domestic XH204 aqueous silicone oil promotes ink flow, leveling, and brightening in water-soluble acrylic inks.

In addition to the above-described anti-crater agent, the non-silicon fluorine-based surfactant is also very effective in preventing the shrinkage of the ink film, improving the leveling, and improving the glossiness of the ink film.

Although there are many types of anti-cratering and leveling agents, their use is limited. If they are used improperly, they will often be counterproductive. Therefore, before use, different strains, dosages, and addition methods should be strictly screened and tested.

Problems in product barcode design and printing

If there are quality problems in the product barcodes, they will bring undue losses to the users or operators at any time, which will cause great harm. Therefore, it is very important to design and print product barcodes correctly. According to experts, the quality issues of bar codes are reflected in design, plate making, and printing.

1. Color matching error

In terms of design, the colors are the most erroneous. There are many types of surface: such as: red and white. The red bar is a bar code printed in red. Although it can be printed beautifully, it cannot be read because the scanning light emitted by the instrument is mostly red, resulting in a very small reflection difference between the two. The smaller the reflection difference, the more Difficult to know. The white bars are printed in light colors, printed in dark colors, and blank areas, also referred to as strips. The number of devices I use at the shop cannot read this bar code.

The correct color combination should be a dark color print, with light or white print blanks and blank areas. It can be seen that bar code designers must understand the bar code optical requirements and the bar code printing standards. When designing, they can not only consider the appearance.

2. Wrong type of barcode

The bar code standard stipulates that each digit of a product barcode consists of seven modules. There can be no more and no less. At present, some bar code module organizations do not have rights and interests. There are many kinds of barcodes, such as bar codes, 39 codes, Kudeba bar codes, and 128 bar codes. Different barcodes are used for different purposes. Only commodity barcodes can be used in the retail industry. Some commodity packaging uses barcodes that are not commodity barcodes. This is also wrong.

3. The zoom factor is too small

"National Standard for Commodity Barcoding" stipulates that the magnification factor of the bar code should be 0.80-2.00, and some bar code magnification factors are not regulated.

4. Improper print position of barcode

The printing position should avoid the seals, joints, and places that are easily worn, covered or deformed. Improper printing of product barcodes will result in delays, misreading or refusal to read, which will bring a lot of trouble to the malls and consumers.

Electric engraving machine engraving head can not action troubleshooting

A hand-held electronic engraving machine of the German Haier K405 introduced by a gravure printing plate company found that the engraved head could not move during the trial carving, and neither could make a head or look up.

It is first suspected that the current supplied by the engraving head drive motor or the current is weak enough to drive. However, after replacing the drive current supply function board, the failure remains. It is also suspected that the drive motor malfunctions near the engraving head drive motor and the motor rattles. Open the cover of the drive motor circuit box and feel the vibration by hand. This shows that there is a drive current and the motor is turning, but the engraving head does not move. Remove the motor production load, power test, found that the speed of the motor with a negative spiral spinning wheel wear is normal, but when the thread wheel is held by hand, the thread wheel immediately stops rotating, feeling that the rotation of the thread wheel is not a little strength, the hand release the thread wheel Slowly turn up and gradually reach normal speed. Based on the above analysis, it may be that the mechanical transmission part inside the motor has failed.

Use pliers to hold the small part of the back of the motor and pull it out. When it is unplugged, it is a micromotor with a reduction gear inside. Use a screwdriver to unscrew the two positioning screws and remove the gear. A total of four sets of reduction gears are found. The two groups in the middle are nearly the same and the spacing is the same. Both sides of the two groups are approximately the same and have the same spacing. When dismantling to a group of gears close to a threaded wheel with a load, it was found that the large gear of one wheel was broken. According to the principle of mechanics, the gear sets with the highest forces among the above four sets of reduction gears should be close to the set of threaded wheels. After analysis, it may be caused by a certain factor that the load is too heavy, and the gear near the spiral spinning wheel is broken due to overload, so the gear can only be empty and cannot be carried.

Wash the oil on the big and small gears with analytical petroleum ether. The later used AB glue sticks the big and small gears and put them back in 1 hour.

Note that in the process of loading, two toothpicks with one end that are sharpened will be inserted into the positioning holes first, and then the reduction gears will be sequentially installed layer by layer. Considering the adhesive fastness of AB glue, the gear can be interchanged with a similar group of similar gears and placed on the side of the micromachine with the least force. Finally remove the toothpick, tighten the tightening screws, insert the micro-motor finishing circuit, power test, everything is normal, troubleshooting.

Using the above method to troubleshoot, maintenance personnel must be familiar with the machine's performance and mechanical and electrical schematics. Normally, when maintenance personnel find that a certain circuit board is not normal, it is usually enough to replace it with a new one. However, the replacement of a K405's engraving head drive motor circuit board took more than 1,000 euros, and using the above method to repair the broken reduction gear requires a little AB glue. I think that, as time permits, carefully check the faulty components and eliminate them by yourself.