A good color engineer, not only is able to quickly match the color you need, must also know a lot about the performance of the pigments and plastic, so as to achieve deployment of masterbatch or plastic products, grasp the real. Rather than merely toning, add pigment in, no matter whether it is toxic, if there are other side effects. Therefore, understanding of toner paint, for an excellent color division, is indispensable.

A. selection criteria, pigment

1. Choose paint should consider the factors

(1) hue, concentration

(2) property

(3) the price

2. Use the minimal pigment type

To obtain stable products. With two color or three colors can allocate, do not choose more paint to allocate.

3. Choose the same type and transparency of pigment

For the purpose of the definition. Using sheet is tasted the most distinctive, but when monochromatic cannot achieve ideal, should choose good syntectonic type and transparent paint, such as different structure type, also specially to choose transparent shape, if choose modulate the opaque pigment is not distinct.

4. Approximate hue of the pigment is used to allocate

(1) using similar colour, it is to point to in a given color the color of the left and right sides, three must be with the two primary colors of light, in the deployment, as far as possible choose similar to sample color pigment to color matching.

(2) the use of complementary relationship, its shortcomings:

Poor definition (a), hue is cloudy.

(b) the color is not stable, easy off color.

B. pigment content analysis

Adjust the color on the scene after the production is a dangerous thing, and physical properties of paint should be fully understood.

1. The tinting strength

Tinting strength in the importance of plastic coloring pigment Tinting strength (Tinting strength) refers to a certain amount of non-ferrous products needed, with the percentage of standard samples Tinting strength. Method of pigment tinting strength said: standard depth, 1/3 standard depth, 1/25 standard depth.

2. Heat resistance

The thermal stability of the pigment is refers to under certain processing temperature and time, without obvious color pigment, tinting strength and performance changes.

Pigments in plastic heat change is composed of the following factors:

1) pigment decomposed by thermal structures, such as azo pigment discoloration due to heat azo base fracture;

2) mutual chemistry between pigments and additives in plastic resin;

3) paint heat dissolved in the resin

4) pigment is heated after its physical properties and particle size change and change.

Note: pigment in the plastics processing heat resistance index is associated with the addition of titanium dioxide concentration, in general, after joining titanium dioxide heat resistance index will fall.

3. The dispersion

Quality not only affects the tinting strength and light dispersion, but also because of poor dispersion uneven colouring, streaks or spots effect color appearance, more serious influence on the mechanical properties of the colouring product.

1) pigment dispersion has a direct influence on optical properties of plastic products, plastic color depth and dispersion is good or bad, transparency, with the increase of pigment dispersed particle size decreased, the colors are also associated with scattered;

2) pigment dispersion in the plastic besides pigment dispersion itself, but also related with other important factors, for example: the performance of the resin in general plastic pigment wetting ability depends on plastic polymer structure on the presence of polar groups. So polyester and similar polarity polymer dispersing ability than excluding polar groups for polyolefin;

3) dispersion process: in the plastic processing, the closer the plastic mixture of softening point, melt dispersion ability, best at these temperatures, can produce within the maximum shear stress;

4. Resistance transference

Migration means pigments from the plastic internal migration to products on the surface (cream) or migrate to plastic and solvents. Pigments in plastic migration have four kinds of forms:

1) BLEEDING (BLEEDING) refers to the plastic objects in contact with others, pigment from coloring plastics migrate to contact with another object

2) the copper light or metallic luster (BRONZING) in coloring plastics surface rendering more apparent metallic luster

(3) spray frost CROCKING OR BLOOMING) has colored plastic products will come with time products fall off the surface of the friction surface products can cause color

4) surface precipitation (PLATE - OUT) plastic mold and roller paint pollution in processing

Migration occurred during plastic pigment and bleeding conditions:

1) in polymer or plasticizer - polymer systems have pigment supersaturated phenomenon;

2) in polymer or plasticizer - polymer systems have pigment molecules must be able to exercise;

3) in polymer or plasticizer - polymer systems have pigment is not fully crystallization;

Coloring pigment of transference and plastic materials in plastic chain rigidity and intermolecular closely related. When plastic plasticizer dosage increase in molecular distance increase, more loose structure, thereby reducing the interaction of the polymer chains, thus make dye migration rate increases, especially when soft PVC color choose paint more attention should be paid to.

5. Light fastness and weather resistance

Hou resistance is the ability to pigment resistance of various climate, including visible and ultraviolet light, moisture, temperature, air oxidation, and the products during the use of chemical reagent.

Pigment used in plastic coloring can light fastness and resistance to weathering can have increased as pigment volume concentration increased, organic pigment volume concentration increase will increase the number of paint surface layer, under the same degree of light, the light fastness is better than concentration, of course when the pigment volume concentration increase the critical pigment volume concentration, the increase in light fastness to the limit.

6. Acid and alkali resistance to solvent resistance to chemicals

Selection of pigment, also should according to the product using the environment to choose, such as unfavorable use cadmium is a pigment ultramarine blue and plastic contact with acid, and chrome yellow unfavorable contact with alkaline storage, etc.

7.Toxicity

Non-toxic products tone color, it is best to use organic pigment, without the use of lead chrome yellow, orange molybdenum, cadmium pigment system, etc.

C. used to use paint matters needing attention

1. Use the deputy hot strong sex pigment

Deputy hot sex is the construction of water of crystallization heat lose moisture and hue change blu-ray, put cold again after absorbing water and hue to restore the nature of the primary colors. Especially in red paint Bordeaux 10 b; Permanent F5R, Brilliant Carmine 6 b there is the phenomenon.

2. Easy to migration of paint (Plate out)

Bordeaux 10 b is common, Brilliant Carmine 6 b, Permant Red F5R using this kind of paint should pay attention to when the color of compound formula, such as the formula of the stabilizer, lubricant, plasticizer, etc to add quantity to check, be very careful processing temperature.

3. Use Disazo yellow (azo yellow) color

Disazo yellow (azo yellow) heated crystal change, tend to be opaque, and amount of plasticizer, easy transport phenomena.

4. Use the metallic powder paint

Metal powder is larger than general pigment, the pigment particle and particle is broken, it is important to pay special attention to the amount of lubricant, and metal powder adding quantity should be limited in the minimum pay attention to the water system, avoid to produce products of defects.

5. The use of Phthalocyanine Blue (phthalein cyanine)

Crystal morphology with alpha Type and beta Type, alpha Type with red light, green beta Type belt, when the temperature exceeds 200 ℃, crystallization changes, alpha Type gradually become beta Type, color gradient of green light. In addition, pale and TiO2 with more problems, crystallization resin (such as PE, PP...) Forming shrinkage rate is greater than the non-crystalline form of resin, forming shrinkage is associated with the species and amount of paint, particularly Phthalocyanine Blue shrinkage rate.

6. How to increase the whiteness

Adjustable plus phthalein green, blue, deep purple or group, combined with fluorescent whitening agent, the effect is better, whitening agent, its content is very low, you should use 1%, and the need to pay special attention to the problem of decentralized.

7. Bright black, carbon black content

Gaining more requirements brilliant black, carbon black is also short of blackness, in general, 2 ~ 7% of the amount added to the limit, such as excessive, damage property.

D. save the problem of the colorant

Pigments, special attention should be paid due to the impact of oxygen in the air, light, water, the change from time to time, especially the Chrome yellow, molybdateOrange, Bordeaux 10 b, Carmine 6 b. Should be packed in brown bottle, and cold in the dark; But if after processing the change will be less, because of the pigment particles has been surrounded by resin and so on, are not directly affected; Has the coloring of volatile, should conclude with the manufacturer standard replacement period.