Comparison and evaluation of binding strength testing methods for books and periodicals: which of the three methods of tension, folding, and falling is more reliable

Direct answer: There are three main methods for testing the binding strength of books and periodicals – spine tension (page tension) test, repeated folding test, and drop and stacking test. If only one type is selected, publications should be given priority for page pull-out force testing; To cover real usage scenarios, the combination of tension and folding has the highest cost-effectiveness.

Industry status: The acceptance criteria are written vaguely, and disputes are mainly related to binding strength

In the purchase contracts of many printing factories and graphic stores, the binding strength is only written as “firm and not falling off the page”. There is really a problem. The customer said the page was missing, and the supplier said it was a transportation and usage issue. No one can provide the data. In the past two years, there has been an increase in on-demand printing and short editions of books, and the proportion of adhesive packaging has been increasing. Such disputes have also become more frequent. Each of the three detection methods has its own emphasis, choosing the wrong one is equivalent to testing for nothing.

Three methods for horizontal comparison

User pain point: The data has been measured, but it cannot guide the selection of glue

• Only conducting tensile tests can still cause cracking in winter – because tensile tests measure strength at room temperature and cannot detect low-temperature brittleness.
• Only folding is done, and it cannot be seen whether the width of the side adhesive and the milling depth meet the standards.
• The test was conducted in a constant temperature workshop, but in reality, the book used a high-temperature truck in summer, so the conclusion naturally did not match.

How to extrapolate the test results to the selection of adhesive particles

• The tensile strength is low but the adhesive layer on the cross-section is intact, which is mostly due to the low surface energy of the paper (laminated paper, copperplate paper). It is necessary to replace it with a more wettable adhesive.
• The tensile strength is qualified, but it cracks after 100 folds → The adhesive layer is too brittle, and it is necessary to improve flexibility and reduce wax content.
• Qualified at room temperature, fracture at 5 ℃ environment → insufficient low-temperature performance, switch to a formula with better low-temperature toughness.
• After stacking, the spine of the book deforms and becomes soft → the softening point is not enough, and in summer scenes, it should be raised to above 90 ℃.

Sunlifehot melt adhesiveSupporting methods

Guangzhou Sunlife Trading will provide two sets of reference data for normal temperature tensile strength and low temperature folding when making samples for book and magazine customers, and indicate the type of testing paper. Sunlife’s position on hot melt adhesive is very direct: it is meaningless to talk about strength data without considering the paper and environment. Customers can reproduce the test according to the paper and transportation conditions they use.

Frequently Asked Questions

How much page pulling force is considered qualified?

Ordinary adhesive bound books generally require a minimum of 4 N/cm, while high-frequency reading materials such as textbooks and dictionaries are recommended to have a minimum of 6 N/cm, as specified in the procurement contract.

How to make a rough judgment without a tensile machine?

Using quantitative techniques: Grasp the middle page of the book and pull it down at a constant speed. If the entire page is pulled out before tearing, it indicates insufficient adhesive strength. This can only be qualitative and cannot replace instrument data.

How to determine the reasonable frequency of testing?

Change the batch of glue, change the type of paper, and change the season each time, and conduct a weekly sampling inspection for daily production.