Primjena organskih pigmenata u plastici i smolama

Synthetic resin and plastic have become important industrial sectors, providing people with various synthetic fibers, light industrial products and special functional materials. With the development of synthetic resin, plastics and synthetic fiber industry, the demand for colorants is increasing year by year. Moreover, according to the characteristics of different colored objects, coloring process and processing conditions, the quality of organic pigments as colorants is updated to higher requirements; the intrinsic quality and application properties of colorants have directly affected the appearance of resins, plastics and synthetic fibers. One of the important factors in application performance (such as weather resistance, strength, etc.).

1. Requirements for performance of colorants in plastics and resins
The organic pigment or inorganic pigment used for plastic coloring must have a desired color, high color strength and vividness, good transparency or hiding power, and also have various application characteristics as described below.
1 Excellent heat stability is one of the important indicators as a plastic colorant.
The colorant is excellent in heat resistance stability and can prevent color change due to decomposition or crystal form change upon heating. In particular, for some resins requiring higher molding temperatures, such as polyester and polycarbonate, colorants with high thermal stability should be selected.
2 Excellent migration resistance, no spray phenomenon.
Due to the different binding forces between the colorant molecules and the resin, pigment molecules of additives such as plasticizers and other auxiliaries can migrate from the interior of the resin to the free surface or into adjacent plastics. This migration is related to the molecular structure of the resin, the rigidity and tightness of the molecular chain, and also to the polarity, molecular size, dissolution and sublimation characteristics of the pigment molecule. The coloring plastic is usually contacted with a white plastic (such as PVC) at 80 ° C and 0.98 MPa for 24 h, and its migration resistance is evaluated according to its degree of migration on white plastic.
3 Good compatibility with resin and easy dispersion.
The colorant should not react with the plastic component or be decomposed by residual catalysts or auxiliaries in the plastic to affect the quality of the colored article. The colorant should have excellent dispersibility, fine particle size and concentrated distribution, and easy to obtain satisfactory vividness and gloss.
4 The organic pigments used for coloring outdoor plastic products should have excellent light fastness and weather fastness.
Therefore, although the inorganic pigment has excellent light resistance, weather resistance, heat resistance and migration resistance, and the cost is low, since the color is not very bright, the variety is small, the chromatogram is incomplete, the coloring strength is low, and several varieties are heavy metal salts, and the toxicity is relatively low. Large, limited in plastic coloring, so more organic pigments are used.

2, the main structure type of plastic colorant
There are two types of colorants for plastic coloring: one is a solvent dye or a few disperse dyes, which are colored by infiltration and dissolution in a resin, such as polystyrene; the other is a pigment, including inorganic pigments and organic pigments. Both are insoluble in the resin and are colored by fine particles.
Organic pigments have become important colorants for plastics and resins due to their wide variety, bright color, high tinting strength and excellent application performance. According to their different types of structures, pigments suitable for coloring with plastics include the following types.
1 insoluble azo pigment
The varieties suitable for plastic coloring are mainly single and double azo pigments with complex structure, usually monoazo pigments with simple structure, low molecular weight, and azo condensation pigments. The chromatogram range is mainly yellow, orange and red pigments. . These varieties are suitable for coloring a variety of plastics and have good application properties. Representative varieties such as azo condensation pigments, CI Pigment Yellow 93, 94, 95, CI Pigment Red 144, 166, 242, etc., benzimidazolone pigments, CI Pigment Yellow 151, 154, 180 and CI Pigment Brown 23, etc. Heterocyclic pigments such as Pigment Yellow 139, 147 and other varieties.
2 lake pigments
Mainly naphthol sulfonic acid (carboxylic acid) red lake pigment, due to large molecular polarity, moderate molecular weight, good thermal stability and high tinting strength, representing varieties such as CI Pigment Red 48:2, 53 : 1, 151 and other varieties.
3 phthalocyanine pigments
Due to its excellent heat resistance, light fastness, weather fastness, high tinting strength and migration resistance, it is suitable for coloring various types of resins and plastics. The chromatogram is only blue and green. Representative varieties are C.I. Pigment Blue 15, 15:1 (stable a type), 15:3 (ß type), 15:6 (ε type) and C.I. Pigment Green 7, 36 and so on.
4 heterocyclic ring and fused ring ketone
Such pigments include quinacridones, dioxazines, isoindolinones, anthraquinone derivatives, 1,4-diketopyrrolopyrrole (DPP), indole ketones and metal complexes. A class of pigments.

3. Coloring of main resin and plastic
The coloring of the resin plastic includes mixing the resin, the plastic directly with the colorant, and the resin dyeing process by the resin dyeing process, which is colored before the resin is made into a fiber. Both coloring techniques require the pigment to have excellent heat stability and good dispersibility. The aggregate particles of the pigment should not exceed 2~3μm. The coarse particles will adversely affect the tensile strength of the fiber and even cause breakage. It is more preferable to use a resin preparation of a pigment instead of a powder pigment. The resin paste coloring method can be classified into Melt Spining, Wet Spinping, and Dry Spining. For example, in the case of melt-spinning, a thermoplastic resin such as polyester, polyamide, polypropylene, or the like is melted in an extruder, extruded through a spinning hole, and then cooled and solidified.
Therefore, the organic pigment as a colorant must not undergo a significant color change at the spinning temperature, and the carrier used for the pigment preparation should be identical or similar to the pigmented polymer.
In recent years, some new heterocyclic organic pigments have been introduced in the market, and different resins such as polyvinyl chloride (PVC), polyester (PET), ABS resin, nylon, and polycarbonate can be selected according to application requirements. Variety.

1. PVC resin colorant
PVC is an important class of thermoplastic materials that are used in a wide range of applications, including low-end and high-end special performance requirements, such as construction materials, automobiles, doors and windows. Due to the low processing temperature, various types of organic pigments can be used for coloring. However, depending on the processing conditions and the end use of the colored product, there are specific choices for the colorant, and the following application characteristics should be satisfied.
When the PVC is colored, the resulting blooming phenomenon can be considered as a partial dissolution of the organic pigment as a colorant at the processing temperature and a recrystallization of the pigment at room temperature. This phenomenon is caused by other polydextrose. It also exists in the middle; especially the soft PVC material will increase the solubility of the colorant due to the presence of plasticizer (softener), resulting in more blooming phenomenon, and it can be seen that increasing the processing temperature will result in significant blooming. It is directly related to their increase in pigment solubility at this temperature.

2. coloring of poly (hydrocarbon) (PO) resin
Polyolefins (Polyolefins) are a wide range of widely used, high-yield plastics that can be classified into three categories based on monomer and density or pressure during processing; a, low density polyethylene (LDPE) or High-pressure polyethylene, the corresponding processing temperature is 160~260 °C; b, high-density polyethylene (HDPE) or low-pressure polyethylene, the corresponding processing temperature is 180~300 °C; polypropylene (PP), processing temperature is 220~300 °C.
Generally, organic pigments are more likely to migrate in LDPE, HDPE, and PP resins. The tendency to migrate includes bleed and spray, which is more pronounced as the melt index increases and the molecular weight of the polymer decreases.
When some organic pigments are colored in polythene plastics, they may cause deformation or plastic shrinkage of plastic products. The reason may be considered as a nucleating agent as a coloring agent to promote the crystallization of plastics, resulting in stress in plastics. When the pigment is needle-like or rod-shaped anisotropy, it is more likely to align in the flow direction of the resin, resulting in a large shrinkage phenomenon, and the spherical crystalline organic pigment or inorganic pigment exhibits a small molding shrinkage. In addition, the dispersibility of the pigment in the polydisperse is important, especially the film or blown film and the melt spin dyeing process. Therefore, the morphology of the pigment preparation or the pigment concentrate is often used to improve the dispersion property; the pigments selected are mostly heterocyclic structures and phenolic lakes.

3. coloring of transparent resin such as polystyrene
Based on thermoplastics plus polystyrene (PS), styrene-acrylonitrile copolymer (SAN), polymethyl methacrylate (PMMA), polycarbonate (PC), etc. are high hardness, case hardened The thermoplastic resin has excellent transparency. In order to maintain the original transparency of the colored article, in addition to the coloring of the above pigments, it is more preferable to use a solvent dye (SDSolventDyes) and a disperse dye (Dis.D.) having high solubility. It is dissolved in plastic during the coloring process to form a stable molecular solution, showing high color strength.
A, good heat stability, to ensure that the color and tinting strength does not change at the processing temperature;
B, excellent light fastness and weather fastness, especially for outdoor coloring products;
C, insoluble in water, to prevent bleeding of plasticized plastics;
D, toxicity indicators should meet the requirements
E. The dye must have sufficient solubility characteristics in an organic solvent, which is an important factor for obtaining a transparent coloring effect.

4. coloration of polyamide (nylon) resin
As the coloring agent of the polyamide, an organic pigment can be used, and a polymer-soluble dye can also be selected, wherein the coloring by the organic pigment can be roughly classified into two different grades of coloring agents, as shown below.
Applicable general varieties C.I.P.Y.147 PY 150 PR 149PR 177 PV 23
Excellent performance PY192 PG 7
For polyester resins (including PET and PBT), pigments can be pigmented, but more are pigmented with polymer-dissolved dyes (ie, dissolved dyes), some of which are suitable for PET coloration, such as PY138, PY147 (respectively Quinoxanes, aminoguanidines and chlorinated condensates) and PR214 and PR242 are suitable for polyester coloration.
The coloring of ABS resin is also mostly solvent dye, which not only has good transparency, but also has good light fastness, and can be used with inorganic pigments to obtain opaque colored products. Commonly used solvent dyes are S.Y.93, S.O.60, S.R.111, S.R.135, S.B.104, and S.G.104 and S.G.3.
Polyurethane (PUR, Polyurethane) is widely used in artificial leather materials. It can be added with plasticizers to improve its softness properties like PVC. At the same time, PUR is used in fabric coatings such as toluene, methyl ethyl ketone, DMF, THF, isopropanol. /toluene mixture, etc., so the colorant should be selected as the solvent resistant property, that is, the pigment which is insoluble in the above solvent, otherwise it is easy to cause migration; at the same time, when the polyurethane foam is made, the colorant should have sufficient stability. .