Coating powder storage stability

Storage stability is the ability of powder coatings to maintain their physical and chemical properties after storage under certain conditions. This method includes dry storage and wet storage of powder coatings to measure different properties respectively.

(1) Glass bottle method (dry method)

1. Instruments and Materials

Constant temperature Drying Oven, can keep (50±5)

°C; balance, sense of quantity. .

1g; glass bottle, 120mL, inner diameter about 40mm;

Small aluminum plate; steel shot ball.

2. Measurement method

(1) Weigh 45g of powder coating sample, put it into a glass bottle, place an aluminum plate on top of the powder coating, weigh 150g of steel balls and put them on the aluminum plate, and seal the glass bottle. At the same time, prepare a sufficient number of glass bottles to determine their sprayability and other properties to be tested.

(2) Put the sealed glass bottle into an oven at (50±5)°C.

(3) Every 24 hours or specified time, take it out to check its caking situation, and do the following tests to determine its storage stability : particle size and particle size distribution (see Chapter 3); gelation time (see Chapter 9) ; If there is agglomeration, measure ; spray the board and bake to check the appearance of the coating film.

3. Reference standards

American Standard ASTM D 3451-2006.

(2) Open method (wet method)

1. Apparatus and Materials

Constant temperature and Humidity Chamber, capable of adjusting temperature (40±3)·c, relative humidity (95±5)%; balance, sensitivity 0.1g; aluminum plate, diameter 50mm; gelation time Tester.

2. Measurement method

(1) Weigh 10g powder coating sample, put it in an uncovered aluminum pan with a diameter of 50mm, and then place the aluminum pan at a temperature 40±3)°C and a relative humidity of (95±5)%. in a constant temperature and Humidity Chamber.

(2) After 48 hours, check the agglomeration of the sample, and measure the gel time and spray the sample to determine its storage stability.

3. Reference standards

American Standard ASTM D 3451-2006.