The main performance and evaluation method of pigment for Color Masterbatch
The selection of pigment for Color Masterbatch should not only refer to the related technical standards of ink and paint, but also the processing and application needs of the products, such as heat resistance, resistance to migration, weather resistance and solvent resistance, as well as the interaction with polymers and additives. The pigment chosen is not only brilliant, but also durable and durable. The main properties and evaluation methods of pigments used for masterbatch are described below.
1. coloring force
The coloring power of a pigment is the amount of pigment required for a certain color product, expressed in percentage of the standard sample's coloring power. That is to take 1g standard sample, add Ag white pigment, and mix it into a certain color mixture. Then take the 1g to test the pigment, add white pigment, until the standard light source observed under the same color as the standard sample mixture, the A color pigment used as Bg, then the pigment of the pigment I: I=B/A * 100%
The tinting strength of pigment is not only related to its properties, but also related to the degree of pigment dispersion. The degree of dispersion mainly refers to the fineness of the pigment. The greater the degree of dispersion, the stronger the dyeing power, but there is a maximum value, beyond which the dyeing power decreases. The above is the standard for the coloring force of ink and paint. The standard of standard sample and sample is suggested to be added to the standard sample and sample, which is measured by the ratio of the same depth, that is, A is the amount of resin added to the standard color plate, and the B is the added tree fat when the color depth is similar to the A color.
2. heat resistance
The heat resistance of pigments used in plastics refers to the degree of change in pigment's color or performance at processing and using temperatures. When considering the heat resistance of pigment, the heating time should also be considered. As plastic is processed into products, the processing method is different and the heating time is different. In the process of use, the use is different and the heating time is different. The heat resistance time of the pigment is generally 4 ~ 10rain. Generally, the higher the temperature is, the shorter the heat tolerance time is.
1) A discoloration for 30min; B for 10min discoloration; C for discoloration within 10 minutes.
There are several ways to test the time of plastic thermometer.
(1) colored plastics were respectively refined at 5min, 10min, 15min and 20min at 180 degrees Celsius.
(2) the coloured plastics were refined at 5min at 220, 200, 180 and 160, respectively, and their color changes were compared.
(3) the injection molding machine used for coloring plastics at 180, 230, 250 and 280 centigrade, the injection period is 10min, and the color and lustre change, or the temperature of the color difference Delta E=3 are called heat resistance.
2) when testing, it is best to indicate the brand number and origin of the resin (sometimes the color difference will exceed the standard due to the same resin in different production plants).
3. resistance to mobility
The resistance to migration of pigments refers to the long-term contact of colored plastic products with other solid, liquid, gas and other state substances, or working in a particular environment. It is possible to have physical and chemical effects with the above substances, manifested as the free surface of the pigment from the interior of the plastic to the product, or to the adjacent plastic or solvent. In the middle.
The migration of pigments in colored plastics is related to the rigidity of molecular chains of plastic materials and the intermolecular close type. When the amount of plasticizers in the plastic is increased, the molecular distance increases and the structure is looser, thus reducing the interaction of the polymer chain, thus increasing the migration rate of the pigment. Especially when soft PVC coloring, we should pay more attention to the selection of pigments.
The test methods for the resistance to mobility of PVC products are as follows: 100 PVC, 65 phr two formic acid, two octyl, L calcium carbide and l phr are made to make thin slices, and the uncoloured PVC sheets are made, and two pieces are exposed to the oven. The two sheets were placed at 70 C for 72 hours. According to the dyeing condition of unpolored PVC sheets, the fastness to dyeing of dyed fabrics was assessed by five grades according to GB 251-2008.
4. light resistance and weatherability
Plastic products such as safety cap, turnaround box, roll shutter, profile and automobile plastic parts are required for good light resistance and weatherability for long outdoor use.
Some pigments will change in varying degrees under light. Among them, most of the inorganic pigments have good light resistance, only a few varieties darkened after exposure to light due to changes in their crystal form or chemical composition. The organic pigment in the plastic products is irradiated by light, which will cause the change of the structure of the pigment molecules and other reasons, and may even fade into gray or white.
The method of measuring light resistance is to observe the color change of the pigment under illumination, and then divide it into eight grades according to the time required for color change. In the ISO regulation, a standard blue pigment is irradiated by a xenon lamp, and the color change is used to determine the grade of light fastness, called ISO blue fastness, and its light fastness is grade 8.
Weatherability refers to the color stability of pigments under natural conditions. In general, the sample is placed outside, and the dip angle is 45. Face to face south, regular contrast test to observe its color change.
The domestic weathering standard is the 5 level expression of GB250-2008 color fastness fading card. The international standard is ISOGrey scale (1~5).
5. chemical resistance
Industrial plastics are often used to store chemicals and as pumps and pipes for transporting acids and alkalis. Therefore, the acid and alkali resistance of pigments should be considered. The chemical properties of acid and alkali should also include the products of resin decomposition, other additives in the products, such as antioxidants, dispersants, and the use of detergents and bleaching agents in the environment.
To measure a pigment
