1. Purpose of painting plastic

About 80% of plastic products must be painted. Its purpose is to:

①Increase beauty of goods to attract attention of consumers, especially some civilian goods such as daily necessities and toys.

② Improving weatherability of product, mainly due to anti-ultraviolet function of dye.

③Special Purpose:

To indicate red, yellow and green traffic lights, black wires are ground wires, etc.

Army style, such as army green (ZCPE-2601).

In agriculture, different crops can be covered with plastic film of different colors, such as red plastic film for tomatoes and yellow plastic film for ginseng, which can greatly increase yields.

Secondly, basic knowledge that plastic color matching personnel should have.

1. Dye effectiveness

Color fastness, shade, heat fastness, light fastness, migration fastness, etc.

2. Main properties of plastic

The color of plastic itself;

Plastic transparency

The shade of plastic.

3. Plastic molding process conditions

4. Types, properties and amounts of auxiliaries for plastic processing

3. Problems to pay attention to when developing a plastic coloring formula

1. Selected pigments should be as small as possible

The fewer types of dyes to use to match color of plastic, better. If color matching can be solved by matching two colors, then three color matching should not be used. If there are too many color matching types, it will not only make color matching difficult, but it is also easy to add additional colors to make color dark. In addition, more varieties selected, greater bias that those varieties will introduce into color matching and production samples due to factors such as dispersibility and coloring ability.

2. Pay attention to shade of paint

Pigments used to color plastics have different shades, for example, carbon black and titanium dioxide are blue and yellow due to different particle sizes, phthalocyanine blue BS is red, phthalocyanine blue BGS is green, permanent yellow GG is green, and permanent yellow HR is red. If you use phthalocyanine blue BGS and permanent yellow GG to match, green will be bright, and phthalocyanine blue BS and permanent yellow HR will make green dull.

When formulating light-colored plastic products, influence of shade of coloring matter creates additional difficulties for color selection.

3. Choose pigments with same characteristics

When choosing color of plastic, attention should be paid to choosing varieties with similar light fastness and weather resistance, otherwise prepared plastic products will be completely different after exposure to sun due to large difference in characteristics. At same time, in process of processing, due to large difference in heat resistance, color change will be caused by change in processing temperature. When matching color of plastic, attention should also be paid to selection of grades with similar dispersibility, for example, use of difficult to disperse organic pigments and easily dispersed inorganic pigments for color matching, a change in shear force during production process will cause color change.

4. Thermochromatic pigment effect

When choosing a color, please note that color of some pigments changes with temperature. For example, certain red pigments and titanium dioxide are used to produce pink. At processing temperature, normal pink color turns to dark orange. This orange color turns pink only after 24 hours at room temperature. Many pigments have this thermochromic effect, but this is not very serious. For this reason, care should be taken to avoid use of pigments with a strong thermochromic effect as much as possible, and special care should be taken not to use pigments.nits with a strong thermochromic effect and other pigments as color matching.

5. Influence of titanium dioxide

(1) Add titanium dioxide to reduce transparency of plastic, and color will become lighter as amount of titanium dioxide increases. Therefore, it is first necessary to determine amount of titanium dioxide when choosing a color. Otherwise, when changing amount of titanium dioxide, amount of other pigments will change accordingly.

(2) Different titanium dioxide has different background colors. For example, fine titanium dioxide obtained by chlorination has a blue tint, and coarse titanium dioxide has a yellowish tint. Pay special attention to this. when blending gray.

(3) The addition of titanium dioxide leads to a significant change in color tone of pigment, especially color change of red variety is largest after addition of titanium dioxide. Huangguanghong will take on a blue hue after adding titanium dioxide, and more added, bluer hue will be. After adding titanium dioxide to particle size of carbon black, small particle size black has a brown light, but turns yellow to gray after addition of titanium dioxide, and large particle size black has a blue light, but turns blue to gray after addition of titanium dioxide.

(4) The addition of titanium dioxide will greatly change characteristics of pigment. After addition of titanium dioxide, many pigments will have poor weather resistance and lower heat resistance temperature, such as permanent red.

6. Resin characteristics

When painting plastic, special attention should be paid to color, transparency and shade of plastic itself.

ABS plastic has a light yellow color. In order to obtain a light color variety with good saturation, it is necessary to increase amount of titanium dioxide to cover yellow. PVC itself yellows, and a small amount of toner or bleach is added to eliminate yellowing to eliminate yellowing.

For pearlescent plastics: higher transparency of plastic, better effect.

7. Effect of various additives in plastics on dyes

To increase thermal stability of PVC, it is necessary to add lead salts and cadmium compounds, which will form black sulfides with some sulfur-containing inorganic pigments.

8. Influence of pigments

Ultramarine Blue contains sulfides which, when mixed with Chrome Orange, form black sulfides.

Cadmium also contains sulfides that react with chromium.

9. Metamerism

Two colors that look same in one light may look different in another.

Direct cause: non-permanent spectral reflection lines.

The reason for this inconsistencytvia:

The selected pigment does not match reference plate

The main material does not match sample

Skin texture surface is inconsistent