To fully understand masterbatches, you must remember these 5 key points!

To fully understand masterbatches, you must remember these 5 key points!

Masterbatches

Masterbatches are a mixture of high-performance and high-concentration color resins made by a large number of pigments or dyes of one or more components and carrier resins through strict processing and dispersion processes. Domestic masterbatches are in great demand and have great development potential. Therefore, the research and development of masterbatch production process technology is very necessary.

Let’s take a comprehensive look at masterbatches, including common classifications, basic ingredients, masterbatch production processes and equipment, and finally take a look at the application and future development of masterbatches.

1. Masterbatch classification

01. Different according to the use

Masterbatches are divided into injection masterbatches, blow molding masterbatches, spinning masterbatches, etc., and each variety can be divided into different grades.

Advanced injection masterbatch is used in cosmetic packaging boxes, toys, electrical housings and other high-grade products; Ordinary injection masterbatch is used for general daily plastic products, industrial containers, etc. Advanced blow molding masterbatches are used for blow molding coloring of ultra-thin products.

Ordinary blow molding masterbatch is used for blow molding coloring in general packaging bags and woven bags. Spunning masterbatch is used for textile fiber spinning coloring, masterbatch pigment fine particles, high concentration, strong coloring strength, heat resistance, good light resistance. Low-grade masterbatches are used to make low-grade products that do not require high color quality.

02. According to the carrier

Divided into PE, PP, PVC, PS, ABS, EVA, PC, PET, PEK, phenolic resin, epoxy resin, acrylic resin, unsaturated polyester resin, polyurethane, polyamide, fluororesin masterbatch, etc.

03. According to different functions

Divided into antistatic, flame retardant, anti-aging, antibacterial, whitening and brightening, transparency increase, weather resistance, matting, pearlescent, imitation marbling (flow grain), wood grain masterbatch, etc.

04. According to the user’s usage

It is divided into universal masterbatch and specialized masterbatch. Low melting point PE masterbatches tend to be used as general-purpose masterbatches for coloring resins other than carrier resins. The vast majority of formal masterbatch enterprises in the world generally do not produce universal masterbatches, the general scope of universal masterbatches is very narrow, and the technical indicators and economic benefits are poor.

The universal masterbatch presents different colors in different plastics, and the coloring effect is not predictable. The general masterbatch affects the strength of the product, and the product is easy to deform and twist, which is more obvious for engineering plastics. For universal masterbatches, higher heat-resistant grade pigments are selected, which costs higher and causes waste.

In the process of processing special masterbatches, it has significant advantages such as high concentration, good dispersion and cleanliness. The heat resistance grade of special masterbatch is generally compatible with the plastic used for products, and it can be used safely at normal temperatures, and will cause different degrees of discoloration only when the temperature exceeds the normal range and the downtime is too long.

05. According to the different colors

It is divided into black, white, yellow, green, red, orange, brown, blue, silver, gold, purple, gray, pink masterbatch, etc.

2. The basic ingredients of masterbatch raw materials

01. Pigments

Pigments are the basic coloring components, and it is best to pre-treat the surface of their fine particles with resin to prevent mutual flocculation and make them easy to disperse. In order to cover and mix evenly, solvents that have affinity for pigments and can dissolve resins are used, such as o-dichlorobenzene, chlorobenzene, xylene, etc. In the case of resin dissolution, the pigment is dispersed, and then the solvent is recovered or removed.

02. Carrier

The carrier is the matrix of the masterbatch. At present, the special masterbatches are selected with the same resin as the carrier, which can ensure the compatibility of the masterbatch and the colored resin, which is conducive to better dispersion of pigments. There are many types of carrier resins, including polyethylene, random polypropylene, poly1-butene, low relative molecular weight polypropylene, etc.

For polyolefin masterbatches, LLDPE or LDPE with high melt index is generally selected as the carrier resin, the processing fluidity is better, and the viscosity of the system is adjusted by blending with the colored resin, which plays the role of wetting and dispersing pigments, minimizing the amount of dispersant, and even without dispersing agents can achieve good dispersion effect, and ensure that the performance of the colored products does not decrease.

03. Dispersant

The dispersant wets and coats the pigment, so that the pigment is uniformly dispersed in the carrier and no longer agglomerates, and its melting point should be lower than that of the resin, which has good compatibility with the resin and good affinity with the pigment. There are many types of dispersants, and low relative molecular weight polyethylene wax, polyester, stearate, white oil, oxidized low molecular weight polyethylene, etc. can be used.

04. Additives

In addition to coloring, masterbatches also add flame retardants, antioxidants, antistatic agents, light stabilizers, etc. according to the user’s multifaceted requirements, and have a variety of functions at the same time. Sometimes users do not require, but masterbatch companies will also recommend adding some additives according to product needs.

3. Masterbatches production process

The production process of masterbatches has strict requirements and can be divided into dry process and wet process.

01. Wet process

Masterbatch material is made by grinding, phase turning, washing, drying and granulation. When grinding pigments, a series of technical tests are required, such as determining the fineness, diffusion performance, solids content, etc. of the grinding slurry. There are four methods of wet process: ink method, rinsing method, kneading method and metal soap method.

(1) Ink method

The ink method is the production method of ink paste. The ingredients are ground by three rollers and coated with a low-molecular protective layer on the surface of the pigment. The ground ink paste is mixed with the carrier resin, plasticized in a two-roll plasticizer, and finally granulated by a single screw or twin screw extruder.

(2) Flushing method

The rinsing method is that the pigment, water and dispersant are sanded to make the particles < 1μm, and the phase transfer method is used to transfer the pigments into the oil phase, evaporate and concentrate dry, and after adding the carrier, extrude and granulate to obtain masterbatches. The phase conversion requires organic solvents and corresponding solvent recovery devices, which is complicated to operate and increases the difficulty of processing.

(3) Pinch and method

The kneading method is to mix the pigment with the oil-based carrier, and then rinse the pigment from the aqueous phase into the oil phase by kneading and suming. The oily carrier coats the surface of the pigment to stabilize the pigment dispersion and prevent agglomeration. Then extrude and granulate to obtain masterbatches.

(4) Metal soap method

The pigment is ground to a particle size of about 1μm, and the soap solution is added at a certain temperature to evenly wet the surface of the pigment particles to form a protective layer of saponification liquid (such as magnesium stearate), which will not cause flocculation and maintain a certain fineness. Then add the carrier to stir and mix at high speed to extrude and granulate the masterbatch.

02. Dry process

Some enterprises prepare pre-dispersed pigments by themselves when producing high-grade masterbatches, and then granulate by dry process. Masterbatch production conditions present a variety of options according to product requirements. High stirring + single screw, high stirring + twin screw is the most versatile production process. In order to improve the dispersion of pigments, some companies grind the carrier resin into powder.

Mixer + single screw, mixer + twin screw are also the process technologies used to produce high-quality masterbatches. At present, masterbatch color measurement and color matching technology are more popular, and more high-performance spectrophotometers are introduced to assist in color matching.

03. Dry process

Some enterprises prepare pre-dispersed pigments by themselves when producing high-grade masterbatches, and then granulate by dry process. Masterbatch production conditions present a variety of options according to product requirements. High stirring + single screw, high stirring + twin screw is the most versatile production process. In order to improve the dispersion of pigments, some companies grind the carrier resin into powder.

Mixer + single screw, mixer + twin screw are also the process technologies used to produce high-quality masterbatches. At present, masterbatch color measurement and color matching technology are more popular, and more high-performance spectrophotometers are introduced to assist in color matching.

4. Production equipment

Masterbatch production equipment includes grinding equipment, high and low speed kneading machine, mixing machine, extrusion granulation equipment, etc. Grinding equipment includes sand mill, cone mill, colloid mill, high shear dispersing machine, etc.

The kneading machine exhausts by vacuum decompression, extracts volatiles and dehydrates; Thermal working conditions are heated by heat transfer oil, steam heating or water cooling; The discharging method is cylinder discharge, valve discharge and screw discharge; The kneading propeller adopts frequency conversion speed governor to regulate the speed.

There are two types of mixers: open mixer and closed mixer. Extrusion granulation equipment includes single screw extruder, twin screw extruder (flat same, flat different, cone same, cone different), multi-screw extruder and screwless extruder, etc.

5. Application and development of masterbatches

Masterbatches are widely used, mainly serving the plastics industry, rubber industry and fiber industry.

01. Plastic

The content of plastic masterbatch pigment is usually between 10% ~ 20%, and when used, it is added to the plastic that needs to be colored in a ratio of 1:10 to 1:20, and the coloring resin or product with the design pigment concentration can be achieved. Masterbatch plastics and coloring plastics can be the same variety or compatible other plastic varieties.

Masterbatches can be single color varieties or multiple pigment color-blocking varieties. The pigment selection meets the processing conditions and quality requirements of plastic products. Masterbatches in the field of plastic products application is relatively mature and common, 85% of the colorants of plastic products use masterbatches, easy to use, no dry powder pigment dust flying problem, completely solve the poor pigment dispersion caused by the product color spot, pigment inconsistency and other drawbacks.

Polyethylene, polypropylene, polyvinyl chloride, plexiglass, nylon, polycarbonate, celluloid, phenolic plastic, epoxy resin, amine-based plastic and other varieties, all have corresponding masterbatches.

In the plastic industry, the market demand for masterbatches is concentrated in engineering plastic products (home appliances, automobiles), building plastic products (pipes, profiles), agricultural film products, plastic packaging products, etc. Home appliances, automobiles, building plastic products industries, etc. have high requirements for masterbatches and large dosages, which has a promoting effect on the development of masterbatches.

02. Rubber

The preparation method of masterbatch for rubber is similar to plastic masterbatch, and the pigments, plasticizers and synthetic resins selected should be varieties that match with rubber. Pigments are mainly used in rubber as reinforcing agents and colorants. Black pigments are dominated by carbon black; White pigments include zinc oxide, titanium dioxide, calcium carbonate, etc.; Other pigments are iron oxide, chrome yellow, ultramarine, chromium oxide green, sunfast yellow, benzidine yellow, phthalocyanine green, lake red C, dioxazine violet and so on.

Wires, cables, tires apply carbon black in large quantities, changing all traditional carbon black to carbon black masterbatch, and its dosage occupies the first position in all masterbatches. At present, domestic and foreign carbon black enterprises can not fully produce carbon black masterbatch, to carry out research on tire carbon black masterbatch, improve its product performance, the market potential is huge.

The use of rubber masterbatches when processing rubber can avoid dust flying caused by powdery pigments and improve the operating environment. Masterbatches are easy to disperse evenly, so that the color of rubber products is uniform and consistent, and the actual consumption of pigments is reduced.

The amount of rubber coloring pigment is often between 0.5% ~ 2%, and the amount of inorganic pigment is slightly more. This kind of processing pigment should be matched with rubber processing technology and quality to meet the needs of the rubber industry, pigment enterprises need to do a lot of applied research to develop and promote the varieties of such processed pigments.

03. Fiber

Fiber solution coloring is when the fiber is spun, the masterbatch is directly added to the fiber viscose or fiber resin, so that the pigment is presented in the filament, which is called fiber internal coloring.

Compared with traditional dyeing, fiber stock solution coloring processes resin and masterbatch into colored fibers and is directly used in textiles, omitting the post-dyeing and finishing process, which has the advantages of small investment, energy saving, no three wastes and low coloring cost, accounting for about 5% at present.

Pigments for fiber coloring masterbatches require bright color, good dispersion, good thermal stability, light resistance, solvent resistance, acid and alkali resistance, bleach resistance, insoluble in water, inorganic or organic pigments can be selected.

Qingdao Yihoo Polymer Technology Co., Ltd. production of ultraviolet absorbers, antioxidants, flame retardants are mainly used in masterbatch products, welcome customers to inquire: yihoo@yihoopolymer.com