Application and Quality Control of Adhesive on Composite Film (2)

3 The corona-treated films are not always uniform. Uneven and uniform surface tension also affects printing and compounding.

(3) Additives: Some additives are added during the plastic processing. This assistant agent plays a very good role in the processing of the film, but it also has a certain influence on the compounding.

3. Effect of laminating adhesive on composite quality In dry composite processing, adhesive is one of the key factors affecting product quality.

(1) Types of Adhesives There are many types of adhesives currently available, which can be divided into one-component adhesives and two-component adhesives. One-component glue refers to a single component. It does not need to be mixed with other components to exhibit viscous glue. It is mostly rubber type, with non-dryness and hot melt, and it does not generate new substances in the compounding process. Adhesives and hot melt adhesives have a low adhesive strength and good initial tack. At the same time, the roller pressure is also required and the temperature is high.

The two-component adhesive refers to a glue that exhibits a viscous property after being mixed with a main component and a curing agent, and is currently a polyurethane type. Polyurethane refers to a polymer having a hydroxyl group in its molecular structure and is obtained by reacting a polyhydric hydroxy compound with a polyisocyanate. In combination with isocyanate active hydrogen, it has high adhesion strength. At present, most of China's A component is a polyol, and B component is a polyisocyanate.

(2) Effect of Other Active Hydrogen on the Adhesive Because the isocyanate's NCO group is a cumulative double bond formed by heteroatoms, it is easy to react with radicals such as -OH, -COOH, -NH2, etc., such as isocyanate and water to form an amine. And emit carbon dioxide; with hydroxyl compounds react to generate carbamate; and -NH2 groups react to generate urea; Therefore, we must pay attention to the storage and use of glue and curing agent, to avoid contact with active hydrogen curing agent.

(3) Influence of Polyurethane Adhesive on Compound Quality Currently, there are many kinds of bi-component adhesives on the domestic market, and the quality is not the same. Therefore, the laminating manufacturers need to have a certain level of judgement criteria in order to control and manage their purchase and use. The quality of the glue is judged mainly from the appearance, adhesive strength, residual solvent and residual monomers of the glue.

a. Appearance: Observe whether it is clear and transparent, whether the color is colorless to light yellow;

b. Bake: Dry the glue in the oven for 2-3 hours (70-75°) and measure the solids content.

c. Dripping: Solvent-soaked composite membrane for solvent resistance test;

d. tear; tear the composite film by hand for the bond strength test;

e. Smell: Whether there is odor or not, to detect whether there is residual monomer, generally speaking, there should be only ethyl taste in the glue;

f. Measurement: The use of various instruments and chemical methods for the inspection of glue and composite membranes, to obtain the corresponding indicators.

4, the impact of thinner on the composite quality Dry compound with two-component adhesive, in order to spread evenly and conducive to infiltration, plus solvent dilution. The main solvents are ethyl acetate, toluene, methyl ethyl ketone and so on. Many factors must be taken into consideration when selecting the solvent. Since toluene is toxic, it is difficult to dry, and it tends to produce residual components. Methyl ethyl ketone smells heavy and the price is high, so ethyl acetate is generally used, and its purity requirements are met. 99%, water ≤ 0.2%, because the curing agent -N = C = O system accumulate double bonds, very lively, and water react to produce amines and emit CO2. (to be continued)