Design of the test scheme for the composite streng

Editor's note: for the quality requirements of book cover lamination, the relevant industry standard CY/t28-1999 "binding quality requirements and inspection methods - Paperback" has many provisions. Other types of laminating products can be evaluated by referring to this requirement. However, the provisions on inspection methods in the standard are relatively general, which is not convenient for practical operation. In this series of quality requirements, the bond fastness between paper and plastic film, that is, the composite strength of coated products, has a greater impact on its overall quality. In view of this factor, the test scheme is designed in order to provide a quantitative and operable evaluation method for the quality inspection of film covered products

1. Introduction

film coated products, that is, printed products processed by film coating, mainly refers to the paper plastic products formed by heating and pressurizing plastic films and printed paper and paperboard through adhesives (or hot melt adhesives). There are two main production and processing processes: pre coating and coating process and instant coating and coating process. The application range of film covering technology is very wide, such as the covers of books, periodicals, picture albums, various certificates, advertising instructions, posters, color printing cartons and other paper products. Film covering technology is often used for surface treatment and processing to achieve better appearance effect. Generally speaking, compared with ordinary paper printing products, film coated products have the following characteristics: the surface is smoother and brighter, and the gloss is higher; The color of pictures and texts is more bright, with a three-dimensional sense; High tear resistance, wear resistance and folding resistance; It has good waterproof, antifouling and chemical corrosion resistance

2. The meaning and influencing factors of composite strength of film coated products

the composite strength of film coated products, simply speaking, refers to the adhesion fastness between plastic film and paper (board) printed matter in film coated products. Its size depends on the adhesion between plastic film, paper (board) printed matter and adhesive (or hot melt adhesive). When laminating, the adhesion mainly comes from the mechanical and physical-chemical adhesion between plastic film, paper (board) printing and adhesive (or hot melt adhesive)

there are many factors affecting the composite strength of coated products, including objective factors brought by production materials such as paper, printing ink, plastic film, adhesive (or hot melt adhesive), as well as subjective factors that can be artificially controlled such as coating process parameters and printing process

all kinds of production materials involved in film covered products are the basic factors to ensure the quality of film covered products. In the selection and use, their combination should be conducive to improving the composite strength, so as to improve the overall quality of coated products. At the same time, once the production materials are selected, the influence of these objective factors on the composite strength can also be basically determined. Therefore, for film covered products, the choice of production materials is very critical

as the film coating process is a surface finishing process for further processing of printed matter after printing, the composite strength of film coated products is affected by the process parameters in the film coating production process, such as the temperature, pressure, speed, coating condition of adhesive, film tension, environmental factors, etc; At the same time, it is also affected by the printing process, that is, the surface state of the printed matter formed after printing, such as the thickness of the ink layer, the area and distribution of graphics and texts, the characteristics of the ink, the use of diluents, the use of powder spraying, the drying of the ink layer, and so on. All these factors will affect the formation conditions of mechanical and physical-chemical bonding between paper (board), plastic film and reducing agent (or hot melt adhesive), cause the change of bonding state between printed matter and plastic film, and thus affect the composite strength of coated products

in a word, the composite strength of film covered products is the result of the joint influence of various factors, and it is also an important parameter for quantitative evaluation of film covered quality. Therefore, according to the existing experimental equipment, referring to the relevant national standards and industry standards, it is of great significance to design an operable experimental scheme to test the composite strength of coated products accurately and scientifically

3. Design of test scheme

any test scheme must have a theoretical basis for testing, reliable testing equipment and feasible testing methods

3.1 theoretical basis, reference standards and requirements for test equipment

film covered products can be regarded as paper (board) and plastic film, which are formed under specific conditions through adhesives or hot-melt adhesives, and are a kind of composite materials exclusively co sponsored by Zhejiang Jixiang Automobile Research Institute Co., Ltd. For composites, peel strength is an important quality evaluation index. That is, under certain test conditions, using specific test equipment, T-Peel the specimen of the specified size at a certain speed, and measure the average peel force between the composite layers. The composite strength of film covered products can be expressed by the peel strength between paper (board) and plastic film, which was officially implemented on February 16 under the universal personal insurance premium rate reform policy

for the determination of peel strength, we can refer to relevant national standards, the most important of which are national standards GB/t2791-1995 "test method for peel strength of adhesive T" flexible materials to flexible materials "and national standards GB/t88o8-1988" peel test method of soft composite plastic materials ". In the process of test scheme design and test preparation, the samples to be tested often turn up or swing down, which cannot form a theoretical "t" shape (that is, the non stripped part and the stripped part of the sample form a "t" shape). If the specimen is fixed by hand and moved with the specimen pulled up to force the specimen to form a "t" shape, it will affect the size of the stripping force, thus affecting the final test results. GB/t2791-1995 clearly stipulates that the "t" type peel test of "flexible material" bonding to "flexible material" is to apply peel force on the unglued end of the sample, so that the sample will peel along the adhesive wire. The angle between the applied force and the adhesive wire can be controlled, that is, the force value can be detected by peeling in a free state without controlling the angle. For film coated products, generally, paper and paperboard that are often processed by film coating can be regarded as "flexible materials". Therefore, film coated products can be regarded as the composite of "flexible materials" and "flexible materials" in most cases, and the determination of their composite strength (peel strength) can be carried out with reference to the provisions of this standard

in the process of testing, abnormal jumping of data often occurs at the beginning and end of the test, which is mainly affected by the fluctuation of stripping force at the beginning and end. In order to improve the accuracy and reliability of the test results and meet the relevant provisions of the two national standards referred to, the selected test equipment should preferably be able to reasonably screen the test data, effectively eliminate the data at the beginning and end of the period, so that it does not participate in the calculation of the results, so as to eliminate the influence of this unstable factor

3.2 selection and adaptability of test equipment

relevant standards stipulate that the test equipment should be a tensile testing machine with a graphic recording device, or other devices that can meet the requirements of this test. According to this regulation, and taking into account the special requirements mentioned above, this design scheme adopts the "XLW series" intelligent electronic tensile testing machine. The equipment mainly has the following characteristics:

(1) it meets the provisions of relevant standards. The "XLW series" intelligent electronic tensile testing machine is designed and manufactured in accordance with the technical requirements of the national standard GB/t17200-1997, and its performance meets the requirements of the national standard GB/t2791-1995 "adhesive T peel strength test method (flexible material to flexible material)" and the national standard GB/t88o8-1988 "soft composite plastic peel tester advanced molding technology society method". At the same time, it can also meet the requirements of many other national standards and carry out many other tests

(2) it has a unique function of "pinching the head and eliminating the tail", which can more accurately reflect the real situation of the test. In the test process, the recording device of the test equipment shall reasonably screen the data obtained from the test results, that is, the data measured at the beginning of the stripping of 25 mm of the sample and 10mm before the completion of the stripping shall be eliminated, and shall not participate in the calculation of the test results. In this way, the influence of the fluctuation at the beginning and end of the test on the test results is eliminated, and the test situation can be more accurately reflected

curve shows the change of peeling force, and people show the effective test range (i.e. the range involved in data calculation). Although the test data of the first 25mm and the last * mm can show that relevant support policies have been issued, they do not participate in the calculation of the final test results

(3) easy to operate and use. The whole machine adopts the high-tech of electromechanical integration, and is equipped with an easy to control operation panel; LCD large screen liquid crystal display; The operation process is simple and easy to master; The test results can be displayed alternately on the screen or printed directly; It has RS232 interface, which can be connected with the computer to further process the data (it should be equipped with relevant software). These characteristics are not only suitable for general technicians to conduct simple tests, but also suitable for researchers to conduct in-depth research

to sum up, the "XLW series" intelligent electronic tensile testing machine can not only meet the provisions of relevant standards, but also meet some special requirements for the determination of composite strength of coated products. It is an ideal testing equipment