The technical properties of adhesives are as follows:
(1) Processability It refers to the performance of adhesives related to the bonding operation, including the preparation, application, drying, and curing conditions of adhesives. It is also an evaluation of the difficulty of the bonding operation. As mentioned earlier, multi-component adhesives need to be mixed on site. Chemically reactive adhesives have requirements for the temperature conditions of the curing reaction. Solvent-based adhesives need to be left to dry for a period of time after application until the solvent evaporates before bonding can occur. These issues must be clarified when selecting and using adhesives to ensure the bonding effect.
(2) Bonding Strength It is a performance indicator that ensures the firmness of the bond. If the bonding strength is insufficient, the bonded objects will fall off. For example, if it is used for wall decoration, the bonded objects may drop down, which will not only affect the decoration quality but may also cause accidents that harm people sometimes.
(3) Stability It refers to the degree of change in the strength of a bonded specimen after being immersed in a specified medium at a certain temperature for a period of time. Examples include water resistance and oil resistance. It is usually expressed by the measured strength or the strength retention rate. For adhesives used to bond finishing materials for floors, exterior walls, bathrooms, toilets, etc., good stability is required.
(4) Durability (or Aging Resistance) With the increase in the usage time, the performance of the bonding layer will gradually deteriorate until it loses its bonding strength. This property is called durability. Because the most widely used adhesives nowadays are organic polymer materials mainly composed of synthetic resins or synthetic rubbers, they are prone to aging and deterioration during use, causing the bonding layer to lose its effectiveness and fall off.
(5) Temperature Resistance Temperature resistance refers to the change in the performance of adhesives within the specified temperature range. It includes heat resistance (under high-temperature environmental conditions), cold resistance (under low-temperature environmental conditions), and resistance to high and low temperature changes. These temperature changes will cause changes in the components of the adhesives, thus reducing the bonding strength until the adhesive layer falls off.
(6) Weather Resistance For bonded components exposed outdoors, their ability to withstand climate factors such as rain, sunlight, wind, snow, and moisture is called weather resistance. Weather resistance also reflects the aging resistance of the bonding layer performance under the long-term influence of natural conditions. Similarly, these natural factors will cause the performance of the bonding layer to deteriorate and affect the bonding strength.
(7) Chemical Resistance Most synthetic resin adhesives and some natural resin adhesives will undergo different changes such as dissolution, swelling, aging, or corrosion under the action of chemical media, resulting in a decrease in the bonding strength.
(8) Other Properties In addition to the properties introduced above (that is, the influence of various usage environmental conditions, such as temperature, humidity, sunlight, chemical media, etc., on the bonding strength of the adhesive layer of adhesives, which comprehensively reflects the usage effect of the bonding layer), other properties of adhesives should also be considered when selecting adhesives, such as whether there is a pungent smell, whether it is toxic, the color of the adhesive, storage stability, storage period, and price. For adhesives used indoors, there should be no pungent smell and no toxicity. If it is necessary to choose an adhesive with a smell, it should be used after the bonding layer is completely dry. Choose an adhesive with a similar color or white color according to the color of the bonded object to avoid the color of the adhesive from contaminating the finish and affecting the decorative effect of the finish. In addition, attention should also be paid to the storage period of adhesives. Because the actual bonding performance (especially the bonding strength) of adhesives that have passed the storage period will be greatly reduced, thus affecting the bonding effect.