How to distinguish the quality of starch glue

If the prepared starch adhesive can be used in production, it should be tested before use, only in this way can we ensure to produce carton products with good bonding quality.

One. Sensory examination

By observing sound, foam, color, silk to identify the quality of adhesives.

1. Listen:

After the adhesive is prepared, when the reaction mixing just stops, the liquid of the adhesive will swirl and crash on the mixing paddle, making a sound like flowing water, indicating good flow performance.

2. look at bubbles:

When the binder is stirred, a small amount of white foam will appear. When the mixture is stopped, it will be observed with glass glue. The small bubbles will rise and burst, and the foam will disappear gradually.

3. Color:

The adhesive shall be light yellow brown, oily, clear and clear without turbidity.

4. Wire drawing:

Dip a small amount of adhesive with thumb and index finger, separate the two fingers after rubbing and contacting each other, and after repeated times, the drawing should be more than 15-20 mm.

Two. Viscosity test

Through sensory testing, we can judge the quality of adhesive at the beginning, but we should also measure its viscosity and initial viscosity, control and adjust the viscosity of adhesive, which is conducive to the infiltration, penetration and diffusion of adhesive molecules on the paper surface. So that it has excellent adhesion performance, improve the initial viscosity and bonding strength.

A certain volume of the adhesive is flowed out of the small hole in the flow cup of the viscometer, and the required time is used to express the viscosity. Test method:

Take the four cups of coating as the testing instrument, and measure more than three times according to the operating procedures. Take the arithmetic mean value of two times close to the viscosity value as the measurement result, and the viscosity index shall be 30-45 seconds

Three. Alkali measurement of initial viscosity

The initial viscosity refers to the degree to which the adhesive and the board are bonded in a short period of time

Test method:

Cut 1ocm × 10cm Ten pieces of box board paper are divided into five groups. One piece of each group is evenly covered with adhesive, and then the other piece is aligned with each other, and then a little pressure is applied. The paper is placed at room temperature, and the starting time is recorded. After 10 minutes, the paper pieces are peeled off in sequence according to the order of adhesion. The paper breaking rate is calculated by the arithmetic average value of five groups according to the percentage of the broken area of paper fiber and the area of the paper piece.

The higher the paper breaking rate, the higher the initial viscosity. The stronger the bond strength of corrugated board is.