Discussion on the process of water-based color coating of steel drum

Text / Liu Shengbo

Hubei Jiaji Synthetic Material Co., Ltd. Liu Shengbo

Common problems in water-based color coating include sag, bleed, splash, and burnt. The generation of these problems may involve the following process parameter problems:

1. barrel temperature during spraying

2, compression ratio and intake pressure

3, leveling time

4, baking temperature curve and time

5, the outlet position

Below we discuss the above issues one by one.

First, the temperature of the barrel before spraying

1, high temperature (70-90 ° C)

Advantages: easy color registration. Disadvantages: need to preheat, high energy consumption, leveling

2, medium temperature (30-50 ° C)

Advantages: low energy consumption. Disadvantages: need to preheat; water-based paint color is medium difficulty

3, normal temperature

Advantages: no preheating required. Disadvantages: need long leveling or long-time low-temperature baking; water-based paint is difficult to color

Second, the compression ratio and intake pressure

1, the compression ratio is 45:1

Large compression ratio, easy to bleed, easy to splash

2, the compression ratio is 32:1

Medium compression ratio, intake pressure should not be too high

3, the compression ratio is 25:1

Medium compression ratio, wide range of intake pressure

4, the compression ratio is 16:1

The compression ratio is small, the intake pressure is required to be large, and bubbles are easily generated.

Third, the leveling time

1, very short (≤ 1min)

Features: Flow adjustment, need high temperature or long time low temperature baking

2, medium (2 - 3min)

Features: good leveling, long-term low temperature baking

3, longer (about 5 minutes)

Features: good leveling, no need for long-term low temperature baking

Fourth, baking temperature curve and time

1, the temperature curve

Before low and high, for example: 90-110 ° C * 4 min + 150 ° C * 7 min

2, baking time

(1) Shorter (≤8min)

(2) Medium (about 12min)

(3) Longer (≥15min)

Fifth, the outlet position

1, the upper air outlet, hot air blowing from top to bottom

(1) The moisture at the top of the barrel is rapidly volatilized, and the viscosity of the coating increases rapidly, resulting in poor leveling.

(2) The top surface coating of the barrel is solidified to form a closed layer, and the lower layer of water volatilizes easily to generate bubbles and pinholes. Not only affects the appearance, but also reduces the corrosion resistance of the paint film

2, side air outlet

3, under the vent, hot air blowing from the bottom up

Summary

After the above comparative analysis, we obtained the following combination of process parameters. Reasonable process parameters are self-evident.

1, the barrel body temperature

(1) Short leveling time + short drying path - ×

(2) Short leveling time + long drying path - √

(3) Long leveling time + short drying path - ×

(4) Long leveling time + drying path length - √

2, the barrel body temperature

(5) Short leveling time + short drying path - ×

(6) Short leveling time + long drying path - √

(7) Long leveling time + short drying path - O

(8) Long leveling time + drying path length - √

3, the barrel body temperature

(9) Short leveling time + short drying path - O

(10) Short leveling time + long drying path - √

(11) Long leveling time + short drying path - O

(12) Long leveling time + drying path length - √

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