Foam printing paste is composed of all-water adhesives, foaming agents, stabilizers, etc. It is a kind of relative that through the mechanical method, a certain proportion of air is evenly mixed in to form numerous fine uniform bubble micro-polymers. A stable dispersion system, which is printed on the fabric under the action of mechanical external forces. Due to the capillary action of the fibers and the wettability of the foam, the foam bursts and forms, the initial viscosity of the colorant is restored, and then the desired uniform printing effect is achieved.
2.1 selection of additives
Foam printing foam size, strength, stability is mainly related to the foaming agent and stabilizer. Therefore, it must be selected so that it has a good compatibility, in order to have a relatively stable foam. Many surfactants can be used as blowing agents. Commonly used sodium dodecyl benzene sulfonate and sodium lauryl sulfate, stabilizers are hydroxyethyl cellulose, sodium alginate, dodecanol, stearic acid and so on. We believe that sodium lauryl sulfate is the foaming agent and stearic acid is the best stabilizer.
2.1.1 The amount of foaming agent
The main role of foaming agent is to reduce the surface tension of water. The amount of blowing agent will directly affect the foaming effect and the stability of the foam. If the amount is small, the surface tension of water cannot be sufficiently reduced, uneven foam will be produced, and the stability of the foam is also poor; if the amount is too much, too much foam will be formed, and the amount of liquid in the foam itself will be reduced and reduced. The wetting ability of the foam makes it impossible for the foam printed on the fabric to rupture and drain quickly after it has been drained, resulting in a poor surface finish of the fabric. Through a large number of tests, it is considered that the amount of blowing agent is suitable between 1% and 1.2%.
2.1.2 The amount of stabilizer
Stabilizers are mainly used to increase the half-life of the foam and extend the life of the foam. The general dosage is controlled between 0.8% and 1%. Too little to achieve the purpose of stability, too much foam wet ability is not easy to break. 2.2 Effect of initial viscosity, pH and temperature on foam stability
2.2.1 Initial viscosity
Foam paste has a certain viscosity in order to ensure the normal working pressure of the foam and increase the thickness of the foam wall. According to the test results, it is considered that under certain conditions, the viscosity should be controlled at 35 Pa·s to 37 Pa·s, and the rotary viscometer should be used to measure the 3# rotor at 30 r/min. The viscosity is too low, the foaming effect is poor, and the foam is not uniform; the viscosity is too high and the printed fabric feels stiff.
2.2.2 pH
Foam-printing thickeners use PTF, the amount of which determines the initial viscosity of the coloring paste. Low pH, PTF can not be fully expanded, so that the rheology of the foam slurry is poor, the pH value is too high and the amount of PTF is increased, the fabric feels hard. The best puffed state of PTF is pH 9-10.
2.2.3 Temperature
The temperature has a great influence on the stability of the foam. Since the bubble is formed by the two phases of liquid and gas, the energy itself is not balanced, and the increase in temperature will exacerbate the thermal motion of the molecule, resulting in the rupture of the bubble. Therefore, a cooling tube is installed on the foam generator so that the produced foam always maintains the same temperature.
2.1 selection of additives
Foam printing foam size, strength, stability is mainly related to the foaming agent and stabilizer. Therefore, it must be selected so that it has a good compatibility, in order to have a relatively stable foam. Many surfactants can be used as blowing agents. Commonly used sodium dodecyl benzene sulfonate and sodium lauryl sulfate, stabilizers are hydroxyethyl cellulose, sodium alginate, dodecanol, stearic acid and so on. We believe that sodium lauryl sulfate is the foaming agent and stearic acid is the best stabilizer.
2.1.1 The amount of foaming agent
The main role of foaming agent is to reduce the surface tension of water. The amount of blowing agent will directly affect the foaming effect and the stability of the foam. If the amount is small, the surface tension of water cannot be sufficiently reduced, uneven foam will be produced, and the stability of the foam is also poor; if the amount is too much, too much foam will be formed, and the amount of liquid in the foam itself will be reduced and reduced. The wetting ability of the foam makes it impossible for the foam printed on the fabric to rupture and drain quickly after it has been drained, resulting in a poor surface finish of the fabric. Through a large number of tests, it is considered that the amount of blowing agent is suitable between 1% and 1.2%.
2.1.2 The amount of stabilizer
Stabilizers are mainly used to increase the half-life of the foam and extend the life of the foam. The general dosage is controlled between 0.8% and 1%. Too little to achieve the purpose of stability, too much foam wet ability is not easy to break. 2.2 Effect of initial viscosity, pH and temperature on foam stability
2.2.1 Initial viscosity
Foam paste has a certain viscosity in order to ensure the normal working pressure of the foam and increase the thickness of the foam wall. According to the test results, it is considered that under certain conditions, the viscosity should be controlled at 35 Pa·s to 37 Pa·s, and the rotary viscometer should be used to measure the 3# rotor at 30 r/min. The viscosity is too low, the foaming effect is poor, and the foam is not uniform; the viscosity is too high and the printed fabric feels stiff.
2.2.2 pH
Foam-printing thickeners use PTF, the amount of which determines the initial viscosity of the coloring paste. Low pH, PTF can not be fully expanded, so that the rheology of the foam slurry is poor, the pH value is too high and the amount of PTF is increased, the fabric feels hard. The best puffed state of PTF is pH 9-10.
2.2.3 Temperature
The temperature has a great influence on the stability of the foam. Since the bubble is formed by the two phases of liquid and gas, the energy itself is not balanced, and the increase in temperature will exacerbate the thermal motion of the molecule, resulting in the rupture of the bubble. Therefore, a cooling tube is installed on the foam generator so that the produced foam always maintains the same temperature.
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