Determination of the bonding strength of corrugated board and its application in production

The ply adhesive strength of corrugated board refers to the tightness of the bond between the sheets of corrugated board Common corrugated board has three layers of board, five layers of board The three-layer cardboard is a kind of plate-shaped object formed by the bonding of a layer of box board (surface paper), a layer of corrugated base paper (corrugated paper) rolled into wave shape in the middle and a layer of box board paper (inside paper); the five-layer cardboard is basically the same as the three-layer cardboard, but there is an additional layer of corrugated paper and a layer of core paper in the middle The quality of corrugated board is directly affected by the tightness and firmness of the bond between the sheets Corrugated board with good adhesion, flat surface, no bubble, no fold, no warpage, no separation between paper pages after processing into corrugated box, rigid appearance, good compression resistance and buffer performance, can effectively protect the internal products from the influence of external adverse factors Corrugated board is made up of face paper and core paper, so the bonding state of face paper and core paper is very important The bonding of corrugated board is not the stronger the better the bonding force, but the right bonding force is required to maintain the normal state of corrugated board If excessive adhesive is used in pursuit of bonding strength, the corrugating top will be deformed In this way, the overall strength of corrugated board will be reduced even though the bonding force is large This requires mastering the bonding strength of corrugated board in the production process of paperboard, combining with the actual production situation, flexible application, reducing costs and generating greater economic benefits To measure the bond strength of corrugated board is to test the bond tightness between sheets of corrugated board with instruments The principle is to insert a needle shaped accessory between the corrugated paper and the face paper (or core paper) of the corrugated board sample, and then press the accessory inserted with the sample to make it move relatively until the bonding part is separated It uses Newton per square meter (n / m2) as the unit to express the magnitude of the bond strength The test instrument used for the determination of the bonding strength of corrugated board shall be the pressure resistance tester of the platen type, whose Platen Size shall meet the selected size of the sample, so that the sample does not exceed the platen, the parallelism deviation of the platen is not more than 1:1000, the horizontal movement is not more than 0.05mm, and the moving speed of the dynamic platen is 12.5 ± 2.5mm/min The test accessories are composed of the upper accessories and the lower accessories, whose function is to apply uniform external force to each adhesive part of the sample Each accessory is composed of needle type parts and supporting parts which are inserted into the space center of corrugated board equidistant The parallelism between needle type parts and supporting parts shall be less than 1% The test method is as shown in the figure According to the different insertion positions of the steel needle, it can be divided into two types: bilateral test and unilateral test The corrugated board in the two-sided test is first peeled on the side with poor adhesion, and only the weaker side can be measured Therefore, the two-sided test can not comprehensively measure the bonding strength of the corrugated board, and only the one-sided test can reliably measure the bonding strength of both sides of the corrugated board The specific test methods are as follows: 1 Cut 10 samples of 25 mm × 80 mm corrugated board without compression from the samples to be tested The direction of the corrugated board is the same as that of 25 mm The edges of the samples must be parallel, and the error shall not be greater than 1 mm 2 Insert the needle parts into the corrugated holes When inserting the needle, it is not allowed to fully insert each hole Pay attention to the separation part When separating the corrugated paper from the face paper, it is not allowed to separate the inner paper or the core paper Insert the upper and lower needle parts in staggered positions, evenly insert them, and then install the supporting parts 3 Put the accessories with the sample into the center of the lower platen of the tester, start the tester, and press the accessories with the sample at the speed of 12.5 ± 2.5mm/min until the corrugated peak and the face paper or the corrugated peak are separated from the core paper or the inside paper 4 Record the value displayed on the tester and read to 1n 5 The result is expressed in the following formula: a = f / s, where a represents the adhesive strength of the sample, expressed in N / m2; F represents the force (average value) required when the sample is separated, expressed in N; s represents the area of the sample, expressed in m2 or cm2 Some problems should be paid attention to when measuring the adhesive strength of corrugated board: 1 The speed of the tester must be 12.5 ± 2.5mm/min, too fast or too slow and the speed will cause the difference of the measurement results 2 The cut sample must be straight, and its long side should be perpendicular to the direction of the corrugated board 3 The accessories shall have supporting parts, otherwise the test error will be caused due to uneven pressure 4 Pay attention to the separated parts of the inserted needle type accessories, and the application of the adhesive strength of each part in the production is of great significance 5 Some of the results of the bond strength measured with an unbraced (comb) accessory may be the tensile strength of the corrugated paper The adhesive strength of corrugated board is one of the physical properties of corrugated board, which is different from other physical properties of corrugated board, and it can better reflect the problems in production process Bursting strength and bursting strength are the main indexes of corrugated board, which mainly reflect the physical strength of raw materials, and the edge pressing strength represents the load, which has little relation with the production process And the bonding strength of corrugated board reflects the tightness of the bonding between the paper sheets of corrugated board As we know, corrugated board is a kind of board formed by bonding box board paper and corrugated paper processed by corrugated bar It is a kind of production technology to process corrugated paper into wavy shape It is also a kind of production technology to glue box board paper and wavy corrugated paper together It can be seen how closely the bond strength of corrugated board is related to the production process In the past, we often ignored the determination of the bonding strength when we measured the physical strength of corrugated board From the point of view of using corrugated board as packaging material, it is possible to do so, because we consider more about the protection function of the corrugated board for the inner products However, from the point of view of production technology, it is obviously incorrect to ignore the determination of adhesion strength In the production practice, we found that the factors affecting the bonding strength of corrugated board mainly include the following aspects: first, the quality of adhesive This is the main factor that affects the adhesive strength of the corrugated board The adhesive is made of starch, polyvinyl alcohol and other viscous substances combined with other chemical substances Its formula, manufacturing process, water proportion and so on play a decisive role in the adhesion between sheets Many carton factories choose adhesive as the main task of QC group activities in the selection of quality control points Second, paper quality In addition to the adhesive as an intermediate medium for bonding, the quality of paper also has a certain impact on bonding Paper quality should pay attention to the water content, sizing, smoothness (roughness) and so on Third, production environment The environment is too wet, the initial adhesion speed between the pages is too slow, and it is easy to separate when entering the next process; the environment is dry, the adhesive loses water too quickly, and the page has not fully absorbed the adhesive, which also affects the adhesion strength Fourth, equipment and processing factors For example, the corrugated bar gap, the uneven surface, the uneven or insufficient pressure of the pressing roller, and the speed can affect the bonding quality of the corrugated board Fifth, the factor of corrugated shape Different shapes have different bonding areas In a certain length, the more the number of ridges, the larger the bonding area, the greater the bonding strength Sixth, human factors The amount of paste used in production should be adjusted according to the speed of bonding Measuring the bonding strength of corrugated board can not only understand the quality of corrugated board, but also control the quality of corrugated board production When it is found that the bonding strength of corrugated board is insufficient, the unfavorable factors can be found out and overcome through analysis As mentioned above, the key is adhesive If the paper, environment, corrugated shape and other factors change, the preparation of adhesive should also be changed accordingly, in order to produce a good bonding corrugated board Through the measurement of the bonding strength of corrugated board, we can master the change of the bonding quality of corrugated board, timely adjust the preparation of adhesive, so as to achieve the purpose of reducing consumption, improving output and quality, and make the production enter into a virtuous cycle state If it is equipment factor, it is necessary to repair the equipment in time If it is the influence of speed, it should be adjusted to the appropriate speed By measuring the strength of each bonding part of the corrugated board, it can be timely and clearly pointed out which machine the poor bonding occurs on, so that the workshop can adjust the production process and improve the process in time By measuring the bonding strength of corrugated board, we can compare and understand the bonding effect of different adhesives At present, a variety of adhesives emerge in endlessly in China, each of which claims that its invention is of high quality, low price and low consumption Through the test of samples, we can compare the advantages and disadvantages of Zui, and select the adhesive suitable for our factory At this time, it is of great benefit to improve the process and use new materials to save costs In a word, in the production process of corrugated board, strengthening the detection of its adhesive strength can timely and accurately obtain the relevant information in production It is very beneficial to use this information to guide production, improve technology and improve product quality This paper briefly discusses the measurement of the bonding strength of corrugated board and its application in production Each enterprise can use it flexibly in combination with its actual situation, and it will produce greater benefits.