Processing skills of the hottest portable paper ba

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Portable paper bag processing skills portable paper bag sealing adhesive strength testing method

portable paper bags are generally made of high-quality and high-grade paper, kraft paper, coated white cardboard, coated paper, white cardboard, etc., which are simple, convenient, and have good printability and exquisite patterns. They are widely used in the packaging of goods in the fields of clothing, food, footwear, gifts, tobacco, alcohol, drugs and so on. In the process of using the handbag, the bottom or side seal of the bag often cracks, which seriously affects the service life of the portable paper bag and the weight and quantity of the items it can hold. The cracking of the seal of the portable paper bag is mainly related to the adhesive strength of the seal. It is particularly important to judge the adhesive strength of the seal of the portable paper bag through the detection technology

the sealing adhesive strength of portable paper bags is specified in qb/t, and the sealing adhesive strength is required to be not less than 2.50kn/m. The sealing adhesive strength shall be measured according to the constant speed tensile method in gb/t

12914. Take any two sample bags, and take 5 samples from the low end and side of each sample bag for test. It is appropriate that the bonding place is in the middle of the sample when sampling. When the sealing is continuous and the material is broken, the sealing strength is expressed by the tensile strength when the material is broken. Calculate the arithmetic mean value of 5 samples at the low end and side respectively, and take the lower of the two as the test result

it can be tested by pn-tt300 computerized tensile strength tester, which is independently developed and produced by Hangzhou Pinxiang Technology Co., Ltd

pn-tt300 computerized tensile strength tester

experimental principle

adhesive strength is the force required to break a seal of a certain width. The instrument adopts a vertical structure, the clamping fixture of the sample is fixed by the lower collet, the upper collet is movable, and the upper collet is connected with a force value sensor. During the test, the two free ends of the sample are clamped in the upper and lower collets respectively, and the sample is stripped or stretched at a certain speed. The force value sensor records the force value in real time, so as to obtain the bonding strength of the sample

test process

1 Sampling

take any two sample bags, and take five samples from the low end and side of each sample bag for test. The sampling width is 15 ± 0.1mm, and the length is at least 250mm

when sampling, it is appropriate to place the bonding part in the middle of the sample

2. Set the parameter

(1) set the test speed to 20 ± 5mm/min; (2) The width of the sample is set to 15mm; (3) The collet spacing is set to 180mm

3. Place the sample

take one of the samples, clamp the two ends of the sample between the upper and lower collets respectively, and each collet should firmly clamp the full width of the sample along a straight line without damage or sliding

4. Test

press the "reset" key to reset before the test. Press the "test" key to start the test, the instrument displays the force value in real time, the test is completed, the upper collet is reset, and the screen displays the test results of bonding strength. Repeat operations 3 and 4 until the test of 5 samples is completed. Press the "Statistics" key to display the statistical results, including the average value, maximum value, minimum value, standard deviation and coefficient of variation of the adhesive strength

5. Test results

calculate the arithmetic mean of 5 samples at the low end and side respectively, and take the lower of the two as the test result

conclusion: the adhesive strength of the seal of the portable paper bag is an important factor to determine whether it is easy to crack in the process of use. To a certain extent, it determines the weight, quantity and service life of the portable paper bag, so we must pay attention to it

although there are many kinds of portable paper bags, the vast majority of portable paper bags on the market are rectangular, with standard shapes. A single order is often printed in a small number. Offset printing is generally used to complete printing. Its production process is relatively simple, and the production can be completed according to the commonly used process methods of offset printing and post press processing. However, if we can make some changes to the process method according to the particularity of paper bags, we can save costs and improve production efficiency. Here are some of my experiences in this regard for your reference

reuse of stencils

in most cases, portable paper bags do not directly package products, but first put the products in cartons or plastic bags, and then put them in portable paper bags, so that they are convenient to carry and look beautiful, which makes customers' requirements for the size accuracy of portable paper bags are often not as strict as cartons. According to the characteristics of portable paper bags, the author makes an accurate statistical summary of the length, width and height of portable paper bags previously produced by our factory, and classifies and numbers them according to their different heights

for example, the height of the portable paper bag is between 25cm and 30cm, and all the molded plates of the portable paper bag within this height range are numbered, placed and kept according to the serial number, and the precise size (including length, width and height) of the molded plate corresponding to the serial number, the layout method of the molded plate, and the distance from the mouth edge of the molded plate to the fold indentation line at the handle are written in the record book. When a customer comes to print portable paper bags, first look up the statistical table, and it is best to have the same size. If there are only portable paper bags of similar size, you can negotiate with the customer whether they can be printed according to the similar size. If it is accepted by the customer, you can use this size for plate making and printing, and then use the existing die plate for indentation processing, which saves the cost and time of making the die plate. For enterprises with large output of paper bags, this can obtain considerable economic benefits. For hand-held paper bags that must be made with new moulds, the new moulds should try to maintain a unified typesetting method, and a unified distance from the mouth edge to the fold indentation line at the handle. After use, they should also be classified and registered in time for future reuse

The middle crossbeam and workbench should be often coated with antirust oil

molding method

1 Thick cardboard is used to replace the indentation line

most of the paper used to make portable paper bags are coated paper or kraft paper with a ration of less than 250g/m2, and the final folding is generally done manually. Therefore, the indentation processing of paper bags generally does not need to use the indentation line to cooperate with the steel line, but uses thick cardboard instead of the indentation line. The specific operations are as follows

(1) first clean the bottom plate of the die-cutting machine, stick double-sided adhesive tape, and then lay a layer of thick cardboard with a weight of about 500g/m2, which is familiar in our daily life, so that it can be firmly adhered to the bottom plate

(2) use a large molding pressure and start the die-cutting machine to indent the thick paperboard. The thick paperboard will appear deep groove marks after repeated heavy pressing. Pay attention not to fracture the paperboard

(3) reduce the molding pressure, put in the paper, and press out the folding trace. This kind of crease should have a certain depth, so that it is not easy to run the line when folding manually, but it should not be too deep, so that the paper is crushed or broken after folding, or because the plastic deformation at the crease is too heavy, the portable paper bag is easy to break in future use, affecting the service life. Especially in the indentation processing of kraft paper, because kraft paper is brittle and its toughness is not as good as coated paper, it is more necessary to properly grasp the molding pressure

in order to make the portable paper bag easy to fold without fracturing, the following points should be paid attention to

(1) the backing paper should have sufficient thickness

(2) press the backing paper out of the groove mark before molding

(3) the pressure during formal molding should be appropriate

(4) along the thread direction of the paper, the paper is easier to fold, and the molding pressure can be smaller; And perpendicular to the direction of the paper strand, the paper is more difficult to fold, and the molding pressure can be increased locally

2. When the paper is folded after being molded, some indentation lines fold the printing surface outward, while others fold the printing surface inward. The most easily broken parts of the portable paper bag in the process of use are the four sides and four vertical lines at the bottom of the rectangle, which are folded outward on the printing side. In order to reduce the damage caused by the folding process of the portable paper bag, the back indentation should be used for the indentation of the portable paper bag, that is, the steel wire contacts the back of the paper during the indentation, so that the crease protrudes towards the printing surface. Because the indentation line should be accurately aligned with the front image of the paper, it is required that the mouthpiece edge and side gauge edge during printing should be consistent with those during molding

paper opening method

because the mouth edge with a width of about 1cm on the printing sheet cannot be printed, and there are regular lines, color codes, etc. outside the scope of the finished product, for general printing, the paper is cut larger than the finished product first, and then the surrounding waste paper edge is cut off with a paper cutter or die-cutting machine during post printing processing. If the indentation processing of portable paper bags is to replace the indentation line with thick cardboard, die cutting and indentation should not be carried out at the same time, so portable paper bags generally only carry out indentation processing, not die cutting processing. If the paper edge is cut off by the paper cutter before the indentation, the positioning accuracy of the indentation will be affected. If it is left to be cut after molding, it is not easy to cut neatly because the paper is deformed during molding. Therefore, the general method is to cut the paper into the unfolding size of the finished product before printing, and only carry out indentation processing after printing, without cutting or die cutting, which not only saves the production cost of the template and the paper cost, but also makes the production process more efficient

for rectangular portable paper bags with length, width and height of a, B and h respectively, the following conversion relationship exists between the finished product dimensions a, B and H and the finished product expansion dimensions a and B, for example, during measurement: the expanded length a=2 × (a+b) + side gluing, the expanded width b= folding +h+ bottom, in which the side gluing is generally 2cm, and the folding is generally 5cm. When the opening size is tight, the side glues and folds can be slightly narrower, and if the portable paper bag is large, it should be slightly wider. Bottom of portable paper bag =0.5 × B+ bottom gluing. The bottom gluing is generally about 1cm. If the portable paper bag is larger, it can also be wider

typesetting method

due to the sheet fed offset printing process, the mouth edge cannot be printed, so the folding edge of the portable paper bag must be used as the mouth edge, and the folding edge is folded into the portable paper bag. Although there is a white edge, it generally does not affect the beauty

the layout of the portable paper bag can be arranged in the order of side, front, side, front and sticky mouth, or in the order of front, side, front, side and sticky mouth. If the portable paper bag with a large area of background color is printed, the former method is more conducive to printing, as shown in Figure 2, which is conducive to making the paper receiving wheel that prevents dirt at the crease, so as to avoid scratching the front of the portable paper bag. The front of the portable paper bag has stricter quality requirements, so it is not suitable to arrange printing on the edge of the paper

if the typesetting method shown in Figure 2 is adopted, the left side of the side gauge must be selected. Because the size of the cut paper cannot be strictly consistent. When the left side is taken as the side gauge edge, that is, the left edge of the paper is taken as the benchmark to locate the position of the image on the paper, if the paper size is inconsistent, it will only affect the size of the adhesive port, and will not affect the product quality within a certain range. On the contrary,

if the right side is used as the side gauge edge, when the position of the image on the paper is positioned based on a certain print sheet, the width of the left side of the paper will exceed or be less than the specified size due to the change of the paper size, which will affect the product quality

usually, regular lines are set outside the range of finished products. When the paper is cut into finished products with a large expansion size, regular lines cannot be printed. Therefore, during typesetting, it must be intentionally added

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