Determination method of Non-volatile content

The non-volatile matter content of the paint refers to the amount of non-volatile matter contained in the paint, which is generally expressed . Non-volatile matter is one of the important quality control items in coating production. Through the determination of non-volatile matter, the amount of film-forming substances in the paint can be quantitatively determined to ensure the quality of the paint and the stability of the batch. The main measurement methods are gravimetric method and volumetric method, and the gravimetric method is mainly introduced below.

Scope and description

Non-volatile content is also called solid content. The test principle of this method is to place a small amount of sample in a pre-dried and accurately weighed container, so that the sample evenly spreads on the bottom of the container, and is dried at a specified temperature. After that, constant weight and weighing.

Instruments and Materials

(1) Glass petri dish, flat-bottomed disc made of tinplate or aluminum, about 75mm in diameter.

(2) The diameter of glass watch glass is 80~100mm.

(3) Put color-changing silica gel or anhydrous calcium chloride in the glass desiccator.

(4) The sense of balance is 0.001g.

(5) Blast constant temperature oven.

(6) The thin glass rod is about 100mm long.

test methods

(1) Petri dish method is suitable for general coatings.

① Bake the dry and clean glass petri dish, tinplate or aluminum flat-bottomed disc and glass rod in an oven at (105±2)"C (or other agreed temperature) for 30min. Take it out and put it in a desiccator to cool to room temperature.

② Weigh the disc with the glass rod, with an accuracy of 1 mg, and then weigh (2 ± 0.2) g of the test product in the disc with the same accuracy (perchlorethylene paint sampling 2~1.5g, acrylic paint and 4~5g of paints with a solid content of less than 15% are sampled, or other quantities deemed appropriate by both parties). Make sure the sample is spread evenly across the pan. If the product contains a highly volatile solvent, use the subtraction method to weigh the sample from the bottle with a

③Put the glass rod and the sample pan together in an oven preheated to (105 ± 2)"C (or other agreed temperature) and keep for 3 hours (or other agreed time). After a short period of heating, remove from the oven Take out the disc, stir the sample with a glass rod to break the surface crust, and put the rod and disc back into the oven.

④ After the specified heating time (or until the sample has constant weight), move the disc and rod into the desiccator, cool to room temperature and weigh , with an accuracy of 1 mg. The test measures two samples in parallel.

(2) Surface dish method 

This method is applicable to high-viscosity coatings such as putty, emulsion and nitro cable .

The volumetric method is suitable for determining the volume of the dry coating that can be —the non-volatile volume method. The test principle of this method is to firstly measure the weight and volume of the unpainted disc , and then measure the weight and volume of the painted disc after drying at a certain temperature and time. Calculate the volume and the volume of liquid paint that forms the dry film. The ratio of these two volumes is the non-volatile capacity of the coating. The results measured by this method can be used to calculate the area that can be coated when paints, varnishes and related products are applied at a certain dry film thickness .