Which kind of color is suitable for PA6 and PA66

Color for nylon

Nylon is mainly used in the automobile industry, electronic industry, transportation industry, machinery manufacturing industry, wire and cable communication industry, film and daily necessities.

 

Nylonis used for manufacturing various bearings, gears, circular gears, cams, bevel gears, oil pipelines, oil reservoirs, Protective cover, support frame, wheel cover, deflector, fan, air filter housing, radiator water chamber, brake pipe, engine cover, door handle. Bearings, gears, pulleys, pump impellers, blades, high-pressure seals, Pads, valve seats, bushings, oil pipelines, oil reservoirs, ropes, transmission belts, grinding wheel adhesives, battery boxes, electrical coils, cable joints, various rollers, pulleys, pump impellers, fan blades, worm gears, propellers, screws, nuts , Oil-resistant gaskets, oil-resistant containers, shells, hoses, cable sheaths, shears, pulley sleeves, bullhead planer sliders, electromagnetic distribution valve seats, cold equipment, gaskets, bearing cages, automobiles and tractors Various oil pipelines, pistons, ropes, transmission belts, zero-fogging materials for textile machinery industrial equipment, daily necessities and packaging films, etc.

The production of packaging tapes and food films (high-temperature films for cooked food and low-temperature films for soft drinks) is also quite large.

 

On October 27, 1938, DuPont announced the birth of the world's first synthetic fiber, and named the polyamide-66 synthetic fiber Nylon [1]. Nylon later became "the general term for all polyamides synthesized from coal, air, water or other substances, which have abrasion resistance and flexibility, and have a protein-like chemical structure.

 

The main chain of polyamide contains many repeating amide groups. Depending on the number of carbon atoms contained in diamines and diacids or amino acids, a variety of different polyamides can be prepared. At present, there are as many as dozens of polyamides. Among them, polyamide-6 and polyamide-66 are the most widely used

 

Nylon has high mechanical strength, high softening point, heat resistance, low friction coefficient, wear resistance, self-lubricity, shock absorption and noise reduction; oil resistance, weak acid resistance, alkali resistance and general solvents; good electrical insulation, Self-extinguishing; non-toxic, odorless, good weather resistance; but poor dyeability

 

1 Colorant suitable for nylon

However, the performance, internal quality and structural characteristics of nylon colorants have become important factors affecting the appearance and performance of nylon products. With the continuous changes and advancements in the processing technology of nylon products, the demand for colorants has increased, and higher requirements have been placed on the structural characteristics, quality, variety and processing technology of nylon colorants.

 

Nylon fibers or nylon textiles can be dyed with disperse dyes, acid dyes (neutral dyes), reactive dyes, direct dyes, etc., or special dyes for printing and dyeing.

 

 

2.  Performance of colorants for nylon

2.1  Heat and light resistance

So far, many organic pigments, inorganic pigments and solvent dyes can be used to color most thermoplastic engineering plastics.As far as organic pigments for plastics are concerned, in addition to certain requirements for their thermal stability, they also need to have better light fastness. Many organic pigments have a significant negative effect on the properties of polyamide melts, so there are certain restrictions on organic pigments used for polyamide coloring.

 

2.3 Chemical stability

There should be no chemical reaction between the colorant and the resin, and should not promote the decomposition of the resin. For highly reactive resins such as polyamide resin (PA), its molten state shows reducibility, and it is easy to change the color of the colorant. Therefore, there are only a few colorants to choose from

 

2.4 Migration resistance

There are three main types of colorant migration: (1) Solvent extraction, that is, bleeding in water and organic solvents; (2) Contact migration, causing pollution of adjacent objects; (3) Surface spraying, coloring when heated The solubility of the coloring agent in the polymer is relatively large, while the solubility of the coloring agent is relatively small at room temperature. Generally speaking, the dispersion of inorganic pigments in polymers is heterogeneous and does not produce blooming phenomenon; while organic pigments

There are different degrees of dissolution in polymers and other organic substances, and migration is relatively easy.

 

2.5 tinting strength

The coloring power determines the amount of colorant used to achieve the target color. Generally speaking, the tinting power increases as the particle size of the colorant decreases. The coloring power of organic pigments is higher than that of inorganic pigments. When color pigments and white pigments are used together, the coloring power can be significantly improved.

 

2.6 Dispersibility

The colorant can only have a good coloring effect if it is uniformly dispersed in the state of tiny particles in the polymer. The pigment contains a lot of aggregated particles, and high shearing force must be used to break up large aggregates to form small aggregates to meet the requirements.

 

3.1 Inorganic pigments suitable for PA

Inorganic pigments have better light resistance, weather resistance, migration resistance, and chemical resistance than organic pigments. They are generally suitable for plastics, but the color strength and brightness are much worse. When a good color is required, organic pigments are preferred. In addition, inorganic pigments have high reflectance and are often used in opaque products.

The inorganic pigments that can be used for nylon are: C. I. Pigment Yellow 184,(Bismuth vanadate), pigment blue 29 (Na6A l4 Si6 S4O20), pigment blue 28,(CoO·nA l2O3), Pigment Green 50 (Co2 TiO4).,Inorganic pigments of titanium white and carbon black have high heat stability and other fastness properties, and can be used as colorants for nylon such as C.I. Pigment White 6.

 

3.2  Solvent dyes for PA

Solvent yellow 21

Solvent orange 63

Solvent red 122

Solvent red 214

Solvent red 225

Solvent blue 70

Solvent blue 132

3.3 Organic pigments suitable for nylon

Generally speaking, compared with inorganic pigments, organic pigments show higher color strength and vividness. The processing temperature of PA is higher, and the heat resistance stability of the pigment is also higher. At the same time, the PA resin shows extremely strong reducibility when it is melted.Many organic pigments for plastics are not suitable for use in nylon.

For example :

A .Azo pigments: Because PA resins show extremely strong reducibility when they are melted, they are commonly used in azo red and azo yellow pigments with good heat resistance in polypropylene fibers. During the nylon melt processing, fading and discoloration will occur. Darkens, not suitable for coloring PA.

B .Pigment: Perylene pigment is one of the ideal colorants for plastic coloring. Because of its good heat resistance stability, it can be used for coloring most plastics. But they will undergo a reversible reduction reaction in the PA melt.

C.Polycyclic ketones (reduced) pigments: In plastics, fused cyclic ketones (reduced) organic pigments have excellent light fastness, good solvent resistance, migration resistance, heat stability, and some of them

D.Phthalocyanine pigments: Due to the planarity and symmetry of the phthalocyanine molecular structure, it has good stability and excellent heat resistance, light, migration, acid and alkali properties. Although the structure of copper phthalocyanine is complex, the raw material cost is low and the yield is high. Therefore, it is a less expensive pigment, and its blue and green pigment varieties are suitable for PA coloring.

E.New metal complex pigments: In recent years, nickel complex pigments containing benzimidazole groups or isoindoline groups have been developed. They also have excellent properties and are suitable for almost all plastics such as PA and PESPC.

Pigment yellow 110

Pigment yellow 147

Pigment yellow 148

Pigment yellow 150

Pigment yellow 187

Pigment yellow 192

Pigment orange 68

Pigment red 149

Pigment red 177

Pigment red 178

Pigment red 179

Pigment red 202

Pigment violet 23

Pigment violet 29

Pigment blue 60

Pigment blue 15:1

Pigment blue 15:3

There are relatively few available structures for blue and green, mainly phthalocyanines, but they can basically meet the application requirements. The red and purple varieties to choose from are relatively abundant, while the yellow and orange varieties are relatively rare. Among the light-colored varieties listed, some have limited application in nylon due to poor water and alkali resistance.

 

Among the varieties of light-colored organic pigments suitable for nylon, there are three important varieties: CI Pigment Yellow 150, 192 and Pigment Orange 68. Their thermal stability, light fastness, solvent resistance and chemical stability are all very good. It can fully meet the requirements of nylon processing and is worthy of attention.

 

Pigment Yellow 150 is greenish yellow , yellow 192 is reddish yellow, orange 68 is reddish orange. These three pigments cover the light color spectrum, and the common disadvantage is that they are not bright enough.

 

Pigment Yellow 150 has been put into production in China by domestic companies in Shenyang, Xiangtan, Jiangsu and other places. Its synthesis process is expressed by the following reaction.

 

Pigment Yellow 192 was first proposed by Sandoz Company in Germany, and is now a newer yellow variety put on the market by Colein Company, which has excellent heat and light fastness properties.

 

Pigment Orange 68 is prepared by the condensation of 5,6-diaminobenzimidazolone and 2-hydroxyl.1. Cai formaldehyde in methoxymethanol and then complexing with nicke

 

The performance of colorants for nylon is one of the important factors to improve the value of colored nylon products. With the continuous development of the nylon industry, the demand for colorants increases, and the performance requirements for colorants will become higher and higher.