11 Kinds of Auxiliaries
Heat stabilizer is mainly used in polyvinyl chloride (PVC) and its copolymers, polyvinyl chloride (PVC) in the hot processing process, before they reach melt flow has a small amount of molecular chain rupture and release hydrogen chloride, the hydrogen chloride is a kind of accelerating molecular chain rupture chain reaction catalyst, so if not break out timely to eliminate hydrogen chloride will make polymer chain constantly cracking of low molecular compounds, So that polyvinyl chloride such plastics can not be processed. Adding appropriate alkaline material in PVC can immediately neutralize decomposed hydrogen chloride, achieve the purpose of stabilizing PVC.
Commonly used heat stabilizers are divided into main stabilizers and auxiliary stabilizers:
Main stabilizer：Mainly contains lead, calcium, cadmium, zinc, barium, aluminum, lithium, strontium and other heavy metal cation salts and soaps. Lead sulfate and lead stearate are the most widely used.
Auxiliary stabilizers：The main ring oxidation oil and ester, while they also have certain plasticizer function.
Antioxidant is a kind of chemical substance, when it is in a small amount in the polymer system, it can delay or inhibit the oxidation process of the polymer, and then prolong the service life of the polymer. According to the molecular structure and mechanism of action, commonly used plastic antioxidants can be generally divided into five categories: blocked phenols, phosphite esters, thiocyanates, compounds and blocked amines (HALS).
Polymers photodegrade when exposed to ultraviolet light. Uv absorber is a kind of chemical substance that can absorb uv or reduce the transmission of UV. It can carry out energy conversion, converting high energy UV light into heat energy or releasing energy in the form of non-destructive longer light wave, so as to protect the polymer from uv damage.
Normasal can be divided into the following categories according to their chemical structure: salicylate, benzenone, benzotriazole, substituted acrylonitrile, triazines and blocked amines.
Light screener is a kind of material that can absorb the light wave harmful to the polymer, and then convert the light energy into heat energy to scatter or reflect the light wave, so as to play a shielding role on the polymer. Light screener mainly carbon black, zinc oxide, titanium dioxide, zinc barium white and other black or white can absorb or reflect light wave material.
Processing AIDS refer to additives used to improve the rheological and molding properties of plastic processing, usually low viscosity or surface energy, with a certain lubrication effect of additives; Mainly include plasticizer and lubricant.
Plasticizer because of its weaken the role of van der Waals force between polymer molecules to increase the mobility of polymer molecular chain, reduce the crystallization of polymer molecular chain and can increase the flexibility, extensibility, plasticity of plastic, reduce plastic flow temperature and hardness, is conducive to plastic products. Commonly used plasticizer has benzene 2 formic acid ester kind, sebacic acid ester kind, chlorinated paraffin.
Plasticizer can be divided into two main plasticizer and vice plasticizer:
The main plasticizer is characterized by good compatibility with resin, high plasticizing efficiency, migration resistance, low volatility, low oil (water) extraction, low temperature flexibility; The compatibility of the vice plasticizer and resin is poor, so it is mainly used together with the main plasticizer to reduce the cost.
Can improve the friction and adhesion between the particles of each layer of plastic and the metal surface of the melt and processing equipment, increase the fluidity of the resin, achieve the control of the resin plasticizing time, maintain continuous production of additives, known as lubricants.
Lubricants can be divided into external lubricants and internal lubricants.
The main function of the external lubricant is to enable the polymer melt to leave the hot metal surface of the processing equipment smoothly. The solubility of external lubricant and polymer is poor, only forming a thin lubricant layer at the interface between polymer and metal. The most commonly used external lubricant is stearic acid and its metal salts.
Internal lubricants are soluble in polymers and can reduce the cohesion between polymer molecules, thus facilitating the flow of polymers and reducing the temperature rise caused by internal friction heat. The most commonly used internal lubricants are low molecular weight polyethylene, etc.
Release agent is a functional substance between mold and finished product. The release agent is chemically resistant and will not be dissolved in contact with the chemical components of different resins (especially styrene and amines). Release agent also has heat resistance and stress properties, not easy to decompose or wear; The release agent is bonded to the mold without transfer to the part being machined and does not interfere with painting or other secondary processing operations. Due to the rapid development of injection molding, extrusion, calendering, molding, lamination and other processes, the amount of release agent is also greatly improved.
Reinforcement materials and fillers
In a lot of plastics, reinforcement material and filler occupy a considerable proportion, the main purpose is: in order to improve the strength and rigidity of plastic products or reduce production costs, generally add all kinds of fiber materials or inorganic matter. The most commonly used reinforcement materials are: glass fiber, asbestos, quartz, carbon black, silicate, calcium carbonate, metal oxide and so on.
Coupling agent is a kind of substance which can improve the interface property between filler and polymer material. Generally, there are two functional groups in the molecular structure of coupling agent: one can react with polymer matrix or have good compatibility; The other can form chemical bonds with inorganic fillers.
Such as: silane coupling agent, the general formula can be written as RSiX3(R is the active functional group with affinity and reaction ability of polymer molecules, such as vinyl, chloropropyl, epoxy, methyl acrylyl, amine and sulfhydryl groups; X is the alkoxy group that can be hydrolyzed, such as methoxy, ethoxy, etc.).
Enhancer or packing with coupling agent, can make its surface to obtain a kind of chemical modification, and the dispersion of inorganic phase and forms a bridge between continuous polymer key, become a kind of composite materials, enhance the role of enhancer or packing, organic silane coupling agent is the most widely used, and the organic titanate coupling agent is a kind of more efficient.
Cross-linking agent is mainly used in polymer materials (rubber and thermosetting resin). Because the molecular structure of the polymer material is linear structure, not crosslinked intensity at the low, easy to break, and there is no elastic, the effect of cross-linking agent is to produce chemical bonds between the molecules of the form, the linear molecules each other together, form a mesh structure, so that increase strength and flexibility of the rubber, rubber cross-linking agent is mainly used in the sulfur, in addition to promoter. General cross-linking agent refers to organic peroxide, such as polyethylene cross-linking agent can use diisopropylbenzene peroxide.
Foaming agent is a kind of material that can make rubber and plastic form microporous structure in a certain viscosity range of liquid or plastic state. According to the mechanism of action, foaming agent can be divided into physical foaming agent and chemical foaming agent. Physical foaming agent: a kind of compound which depends on the change of its physical state in the foaming process to achieve the foaming purpose; Chemical foaming agent: Thermal decomposition at a certain temperature to produce one or more gases to foam polymers.
Nucleating agent is suitable for polyethylene, polypropylene, such as incomplete crystalline plastics, by changing the crystallization behavior of resin, accelerate the crystallization rate, increase the crystallization density and grain size ultra-micronization, and shorten the molding cycle, improve product transparency, surface luster, tensile strength, rigidity and thermal deformation temperature, impact resistance, creep resistance and other physical and mechanical properties of new functional additives.
Colorants are insoluble in common solvent chemicals, so to obtain the desired coloring properties, pigments need to be mechanically dispersed evenly into the plastic. Inorganic pigments have excellent thermal stability and photostability, low price, but poor coloring power and high relative density. Organic pigments have high coloring power, bright color, complete chromatography and small relative density. Their disadvantages are heat resistance, weather resistance and hiding power, which are inferior to inorganic pigments. Colorants mainly include masterbatch and fluorescent whitening agent.
Masterbatch is a super constant pigment or dye evenly attached to the resin and the system of aggregates. Its basic composition includes: pigment or dye, carrier, dispersant, additive; Has the following advantages: to maintain the chemical stability of pigment and color stability, improve the dispersity of pigment, simple operation, easy color transfer, clean environment, save time and raw materials.
Fluorescent brightener is a kind of fluorescent dye, or white dye, which is also a complex organic compound. Its characteristic is that it can stimulate the incident light to produce fluorescence, so that the dyed material can obtain the glittering effect similar to fluorite, so that the material is very white to the naked eye. According to the parent classification of fluorescent brighteners, they can be roughly divided into nine categories, including carbon rings, triazinylamino stilbenes, stilbenene-triazoles, benzoxazoles, furans, benzofurans and benzimidazoles, 1, 3-diphenyl-pyrazoline, coumarins, naphthalimides and hybrids.
As safety awareness grows, more and more people are buying antibacterial plastics. And antibacterial plastics all use antibacterial agents. Antibacterial agent refers to the chemical substance that can keep the growth or reproduction of certain microorganisms (bacteria, fungi, yeast, algae, viruses, etc.) below the necessary level for a certain period of time. Antibacterial agent is a substance with bacteriostatic and bactericidal properties.
The additives that slow the combustion of plastics are called flame retardants, and most plastics containing flame retardants are self-extinguishing or have a slowing combustion rate.
Every body has an electrostatic charge of its own, which can be negative or positive. Static charge aggregation of life or industrial production is affected or even harm, will gather harmful charge guidance/eliminate it does not cause inconvenience or harm to production or life chemical substances called antistatic agent. Antistatic agents generally have the characteristics of surfactants, and have both polar and non-polar groups in structure. Commonly used polar groups (namely hydrophilic groups) include: anions of carboxylic acid, sulfonic acid, sulfuric acid and phosphoric acid, cations of amine salt and quaternary ammonium salt, and groups such as -OH and -O-; Commonly used non-polar groups (that is, oil-loving groups or hydrophobic groups) alkyl, alkyl aryl groups. There are five basic types of antistatic agents: amine derivatives, quaternary ammonium salts, sulfate, phosphate, and polyethylene glycol derivatives.