Monday, December 17, 2012

How to Determine the Quality of Adhesive?

A sufficient adhesive strength

Firstly, the adhesives must have a sufficient adhesive strength to ensure that the bonding does not affect the function of the paper products. We have to judge whether the adhesive bonding strength is qualified, then tear the two sticky material along the adhesive sealant interface, if it is found that the sticky material was torn destroyed, the bonding strength is sufficient; while if the bonding interface is just separated which indicates that adhesives intensity is insufficient. The adhesives with poor performance will appear the phenomenon of unglued and film crisp after it has been stored in high or low temperature for a period of time, so it is necessary to make the high-temperature thermal change and low temperature embrittlement experiments to determine whether its quality is reliable. The test method of high-temperature is to put the tray with the completely cured thermal bonding part in a oven with 60 ° C temperature to be baked for 24 hours, and after cooling, flap the tray junction until their separation, if the stick material is torn, which indicates that the heat resistance of the adhesive is excellent, if they are sticky material intact, just the bonding interface is disengaged, indicating the high heat resistance; low temperature embrittlement test is to put the cured tray in the -15 ℃ environment completely to be frozen for 24 hours, and the determination method is the same with high temperature thermal deformation test method.

smt adhesive

Drying rate of the adhesive sealant

When purchasing the adhesives, such as smt adhesive, we must measure whether the drying rate matches with the bonding process. The general manual bonding process is slower, which requires a longer initial dry time; while the speed of the machine bonding process is quick, requiring short early dry time. The vast majority of cases require the shortest dry time, in order to proceed to the next step as soon as possible.

Viscosity of the adhesive sealant

The viscosity is the most important factor affecting adhesives quality. If the viscosity is too large, then the coating is thicker, the glue consumption is larger and dried capacity is slower, but also affect the surface wetting and penetration on the adherend, which in turn directly affect the adhesive strength; if the viscosity is too small and the coating layer is thinner, the excessive drying is prone to issues such as adhesion failure. Packaging enterprises must make the viscosity testing from time to time to ensure its adhesion strength in the ideal range. The desired viscosity range of Various adhesives is not the same, such as corrugated board line binder is 50 ± 15 seconds, automatic Laminator glue of 50 ± 10 seconds, manual laminating glue of 70 ± 15 seconds, sticky box with glue.

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This article is come from: http://www.soundspeakers.cn/index.php/how-to-determine-the-quality-of-adhesive.htm

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