A Must-read for Plastic Modification Factories
What are plastic additives?
Plastic/polymer additives are chemical substances added during the plastic production process to improve the characteristics of the plastic in terms of performance, processability, and appearance. Common plastic additives include plasticizers, stabilizers, antioxidants, UV absorbers, fillers, and more. These additives can be combined according to different requirements to meet the performance requirements of plastic products. This article provides a brief introduction to the performance, characteristics, and applications of the 12 most commonly used additives.
Types of additives to enhance the processing characteristics of substrates:
① Flowability: lubricants;
② Thermal stability: heat stabilizers, antioxidants;
③ Dispersion: processing aids, dispersants;
④ Compatibility: compatibilizers, coupling agents;
⑤ Melt strength: crosslinking agents, viscosity enhancers.
Types of Additives to improve the physical and chemical properties of substrates:
① Rigidity, strength: fillers, nucleating agents;
② Impact resistance: impact modifiers;
③ Heat resistance: fillers, nucleating agents;
④ Flame resistance: flame retardants;
⑤ Weather resistance: stabilizers, UV stabilizers;
⑥ Conductivity: antistatic agents, conductive fillers;
⑦ Color: pigments;
⑧ Softness/hardness: plasticizers;
⑨ Density: foaming agents;
⑩ Transparency: nucleating agents;
⑪ Hygiene: antibacterial agents.
⑫ Laser sensitivity: laser marking additives
The 12 most commonly used plastic additives in plastic modification:
1. Stabilizers
Polymer stabilizers are chemical substances that prevent plastic from deteriorating, aging, or breaking during processing, use, and storage due to factors such as heat and light. Stabilizers protect plastic by absorbing or reflecting ultraviolet light, as well as by absorbing or neutralizing acidic substances.
Common stabilizers include UV inhibitors, antioxidants, light stabilizers, and heat stabilizers.
UV-resistant additives for plastics are a common type of plastic additive. They can absorb or reflect ultraviolet rays, thereby preventing the oxidative reaction of plastics caused by UV radiation.
Common UV-resistant additives for plastics:
① Absorbing UV Additives: These additives can absorb ultraviolet light and convert it into heat energy, thereby preventing the oxidative reaction of UV light on plastics. Common absorbing UV additives include phenols, benzophenones, and benzimidazoles.
② Reflecting UV Additives: These additives can reflect ultraviolet light, preventing it from entering the interior of the plastic and reducing the oxidative reaction of UV light on plastics. Common reflecting UV additives include titanium dioxide and zinc oxide.
③ Absorbing and Reflecting UV Additives: These additives can both absorb and reflect ultraviolet light, providing more effective protection against the oxidative reaction of UV light on plastics. Common absorbing and reflecting UV additives include organic-inorganic hybrid materials.
It is important to note that different plastic materials have different requirements for UV-resistant additives. Therefore, the selection and use of UV-resistant additives should be based on specific circumstances.
The Top UV-Resistant Plastics for Manufacturing
These additives prevent oxidation reactions, thereby preventing plastic from deteriorating, aging, or breaking during processing, use, and storage. The function of antioxidants is to delay the decomposition of plastics caused by oxidation, thereby extending the lifespan of plastic products.
Antioxidants used in the plastics industry can be classified according to their functions:
① Oxidation Chain Reaction Inhibitors: Examples include alkyl phenols, such as butylated hydroxytoluene (BHT), aromatic amines, phenyl-B-naphthylamine, alkyl quinone, alkylidene bisphenol, alkyl phenol-thioether, and phenyl salicylate.
② Peroxide Decomposers: Examples include the thioether series, the propionate ester, organic phosphites, and disulfide sulfonic acid salts.
③ Heavy Metal Deactivators: Examples include amide compounds, hydrazine compounds, and aromatic amine compounds.
These additives can absorb or reflect light to protect plastics from light-induced damage. Light stabilizers are primarily used in polyolefins, especially polypropylene. Polyvinyl chloride, polycarbonate, and polyester also use a small amount of light stabilizers, typically in a dosage of about 0.1% to 0.5%.
Based on their mechanisms of action, light stabilizers can be classified into UV absorbers, quenchers, and light blockers.
① UV absorbers strongly absorb UV light in the wavelength range of 290 to 400 nm. Two of the most effective varieties are 2-hydroxy-4-octoxybenzophenone (UV-531) and 2-(3′,5′-di-tert-butyl-2′-hydroxyphenyl)-5-chlorobenzotriazole (UV-327).
② Quenchers are mostly organic complexes of nickel. They can rapidly and effectively quench (return to the equilibrium state) the excited state molecules that absorb energy, thereby avoiding the initiation of photochemical reactions.
③ Light blockers reduce the transmission of UV light. Carbon black is commonly used as a light blocker.
④ New types of hindered amine light stabilizers are mainly derivatives of tetramethyl or pentamethyl piperidinyl. They have comprehensive functions of capturing free radicals, quenching singlet oxygen, and decomposing peroxides, making them highly effective light stabilizers.
The main function of heat stabilizers is to prevent thermal degradation during processing and aging during long-term use. They are primarily used in polyvinyl chloride (PVC) and PVC copolymers. The dosage of heat stabilizers in flexible products is around 2%, while in rigid products, it ranges from 3% to 5%.
The main categories of heat stabilizers include salt-based lead salts, fatty acid soaps, organotin compounds, organic auxiliary stabilizers, and composite stabilizers.
① Salt-based lead salts (also known as basic lead salts), such as tribasic lead carbonate and dibasic lead phosphite, were used earliest and are still widely used. They have good heat resistance, electrical insulation, and weather resistance. However, they are toxic, opaque, and have poor dispersion.
② Fatty acid soaps, mainly cadmium, barium, calcium, zinc, and magnesium salts of stearic acid and lauric acid, are commonly used. Cadmium soaps are highly toxic, while barium soaps also have some toxicity. However, calcium soaps and zinc soaps are non-toxic.
③ Organotin compounds are the fastest-growing category in recent years. They have excellent transparency, and many varieties exhibit outstanding heat resistance and weather resistance, making them essential heat stabilizers for rigid transparent products. Dibutyltin diacetate and dioctyltin are the most widely used non-toxic stabilizers.
④ Phosphite esters and epoxy compounds are commonly used as auxiliary stabilizers in the formulation of composite stabilizers. Composite stabilizers include general cadmium-barium (zinc) stabilizers, sulfide-resistant barium-zinc stabilizers, non-toxic calcium-zinc stabilizers, and organotin compounds. They are often in liquid.
2. Antistatic agents
Antistatic agents are substances used to impart conductivity to plastics to prevent static accumulation. When selecting antistatic agents, the choice should be based on the plastic substrate, fillers, additives, and performance requirements. The dosage of common antistatic agents ranges from 0.1% to 3%.
The commonly used antistatic agents in the market are thermoplastic elastomers with polyester as the soft segment and polyamide as the hard segment. They are mainly used in plastic products such as ABS, PC, and PP, and undergo processes such as compounding and extrusion before product molding.
Antistatic agents are commonly classified into cationic and anionic types, and their use in plastic does not affect transparency. Commonly used antistatic agents include quaternary ammonium salts, ethoxylated amines, fatty acid esters, and sulfonated waxes.
Characteristics of plastic antistatic agents:
① Cationic antistatic agents have good effectiveness in polar matrices but may have adverse effects on thermal stability.
② They have good compatibility with the raw materials and are not affected by temperature and humidity, with no precipitation.
③ They effectively prevent product dust adhesion, which can affect appearance and performance.
④ They significantly reduce the surface resistivity of the product, preventing dangers caused by discharge and minimizing damage caused by static electricity.
⑤ They do not affect the color of the substrate and can provide additional functionalities to the plastic.
3. Blowing Agent
Plastic Blowing agents are used to create a foam structure in plastics, reducing weight and enhancing insulation properties.
There are three main types of blowing agents for plastics:
① Nitrogen, carbon dioxide, and air can be directly injected into the molten plastic to initiate foaming.
② Volatile liquids such as butane, pentane, petroleum ether, and dichlorodifluoromethane expand and foam the plastic when heated. This type is commonly used for polystyrene foams.
③ Decomposing chemical blowing agents are typically solid powders. When heated, they decompose and release gas (usually nitrogen or carbon dioxide), creating a cellular structure in the plastic and reducing weight. Organic azo compounds such as azodicarbonamide (ADC) and azobisisobutyronitrile (AIBN) are commonly used chemical blowing agents.
Plastics that can be foamed using blowing agents include ABS, PS, PVC, PU, EVA, PE, PP, and others.
4. Flame Retardants
When plastics with flame retardants are exposed to flames, they can suppress the spread of the fire and prevent the formation of smoke. Once the flame is removed, the combustion will stop.
Flame retardants are generally classified into brominated flame retardants and halogen-free flame retardants.
- Brominated flame retardants include brominated epoxy, decabromodiphenyl ethane, and brominated styrene. They are often used in combination with antimony trioxide. The advantages of brominated flame retardants are that they can achieve good flame retardant effects with relatively small amounts, and they have a high cost-effectiveness. However, during combustion, they may generate toxic and carcinogenic substances such as polybrominated dibenzodioxins and polybrominated dibenzofurans, which do not meet environmental requirements.
- Halogen-free flame retardants include inorganic metal hydroxides, phosphorus-based compounds, silicone-based flame retardants, and nitrogen-based flame retardants. The advantages of halogen-free flame retardants are that they are environmentally friendly. However, they usually require larger quantities and have relatively poor compatibility with plastics.
5. Lubricants
Plastic lubricants are chemical substances used to reduce friction and wear between plastic products. They provide lubrication, making plastic products operate more smoothly and extending their service life.
Plastic lubricants can be divided into internal lubricants and external lubricants.
- Internal lubricants are chemical substances added to plastics that can lubricate between polymer chains. They can reduce the viscosity of plastics and decrease energy consumption and mechanical wear during processing. Common internal lubricants include waxes, stearate esters, and paraffin.
- External lubricants are chemical substances that are coated on the surface of plastic products to reduce friction between plastic surfaces. External lubricants are usually in liquid or powder form and can be applied to plastic products through spraying, impregnation, or coating. Common external lubricants include silicone oil, polytetrafluoroethylene (PTFE), and graphite.
The selection of plastic lubricants depends on the specific plastic-type, processing method, and application requirements. It is important to control the amount of lubricant used to avoid adverse effects on the physical properties and appearance of plastic products.
6. Plasticizers
Plasticizers are additives used to improve the flexibility and plasticity of plastics. They can increase the elongation and bending properties of plastics, making them easier to process and use.
Plasticizers are typically divided into two categories: soluble plasticizers and insoluble plasticizers.
- Soluble plasticizers are chemicals that can be miscible with plastic polymer chains. They form a dispersed phase in the plastic, altering the molecular structure and increasing the flexibility and plasticity of the plastic. Common soluble plasticizers include phthalates and epoxy esters.
- Insoluble plasticizers are chemicals that cannot be miscible with plastic polymer chains. They are usually in the form of particles or granules and can form a dispersed phase in the plastic, increasing its flexibility and plasticity. Common insoluble plasticizers include internal and external lubricants for polyvinyl chloride (PVC) and stearate esters.
The selection of plasticizers depends on the specific plastic-type, processing method, and application requirements. It is important to control the amount of plasticizer used to avoid adverse effects on the physical properties and environmental safety of plastic products. Some soluble plasticizers, such as phthalates, have been considered to have potential risks to human health and the environment, so their safety and environmental friendliness should be taken into account when using them.
7. Pigments and Coloring Agents
Plastic pigments are additives used to color plastic products. They are typically made from organic pigments, inorganic pigments, or pigment mixtures. Plastic pigments have good light resistance, heat resistance, and chemical resistance, allowing them to maintain long-term color stability in plastic products.
Coloring agents are chemical substances used to color various materials. In plastic products, coloring agents are usually organic pigments, inorganic pigments, or dyes. Coloring agents can dissolve or disperse in plastics to achieve the desired color. Compared to plastic pigments, coloring agents typically have higher color intensity and transparency, allowing for deeper coloring effects.
Plastic pigments and coloring agents play an important role in the coloring process of plastic products. They provide a wide range of color choices for plastic products and can meet different application requirements. Whether it is plastic pigments or coloring agents, it is important to strictly control the amount and ratio used during production to ensure color stability and quality of the final product.
8. Catalysts
Plastic catalysts are chemical substances used in the production process of plastics to facilitate reactions and curing, thereby speeding up production. Plastic catalysts can alter the molecular structure of plastics, adjust their physical properties, and improve processing performance.
Common 4 types of plastic catalysts:
① Acid catalysts: Acid catalysts promote the polymerization reaction of plastics, leading to the formation of larger molecular chains. Common acid catalysts include sulfuric acid, phosphoric acid, and ammonium chloride.
② Base catalysts: Base catalysts regulate the polymerization reaction of plastics, resulting in the formation of smaller molecular chains. Common base catalysts include sodium hydroxide, potassium hydroxide, and sodium carbonate.
③ Transition metal catalysts: Transition metal catalysts catalyze the polymerization reaction of plastics, facilitating the formation of molecular chains. Common transition metal catalysts include titanium, manganese, iron, and cobalt.
④ Heterocyclic catalysts: Heterocyclic catalysts improve the thermal stability and weather resistance of plastics. Common heterocyclic catalysts include organotin compounds, organoantimony compounds, and organosilicon compounds.
Choosing the appropriate plastic catalyst requires considering the type of plastic, the desired reaction process, and the target properties. During usage, it is necessary to follow the specific instructions for the catalyst and control the amount and reaction conditions to achieve the desired plastic performance and quality.
9. Adhesives
Adhesives are used to bond different plastic materials together, creating more complex products.
Common 4 types of plastic adhesives:
① Organic solvent-based adhesives: This type of adhesive is typically based on organic solvents, such as chlorides, ketones, or alcohols. These solvents can soften the plastic surface, making it tacky, and form a strong bond upon curing.
② Two-component adhesives: These adhesives consist of two components, usually a resin and a curing agent. Before use, the two components need to be mixed together and then coated onto the plastic surface. As the curing agent reacts, the adhesive forms a strong bond.
③ Hot melt adhesives: Hot melt adhesives are plastic glue sticks heated with a hot glue gun. They melt at high temperatures and form a strong bond upon cooling. Hot melt adhesives are suitable for many different types of plastics but may have relatively lower bonding strength.
④ UV-curing adhesives: This type of adhesive requires UV light exposure to cure. UV-curing adhesives are suitable for transparent or translucent plastics, such as acrylic.
Choosing the appropriate plastic adhesive requires considering the type of plastic, surface preparation, bonding strength requirements, and usage environment. During usage, it is necessary to follow the instructions provided by the adhesive manufacturer and ensure proper surface preparation and bonding conditions to achieve optimal bonding results.
10. Fillers
Fillers are materials added to plastics to modify their properties and characteristics. They can increase the strength, stiffness, heat resistance, and wear resistance of plastics while reducing cost and density.
Common 4 types of plastic fillers:
① Fiber fillers: such as glass fibers, carbon fibers, aramid fibers, etc. Fiber fillers can increase the strength and stiffness of plastics and improve impact resistance.
② Particle fillers: such as silicates, calcium carbonate, talc, etc. Particle fillers can increase the hardness, wear resistance, and heat resistance of plastics while reducing costs.
③ Microsphere fillers: such as glass microspheres, ceramic microspheres, etc. Microsphere fillers can reduce the density of plastics while improving their insulation and acoustic properties.
④ Nanoparticle fillers: such as nanoparticles, nanofibers, etc. Nanoparticle fillers can significantly improve the mechanical properties, conductivity, and flame retardancy of plastics.
The selection of plastic fillers should be based on the specific type of plastic, processing technology, and application requirements. During use, it is important to control the amount and dispersion of fillers to ensure the performance and appearance quality of plastic products. Additionally, the selection of fillers should also consider their impact on the environment and sustainability.
11. Defoamer
Plastic defoaming agents, also known as plastic drying agents or plastic defoaming masterbatches. These masterbatches not only remove moisture from plastic formulations but also enhance the density and smoothness of the final products, thereby improving their physical and mechanical properties. By increasing the dosage of colorants, fillers, and recycled materials, one can sustain normal production while reducing manufacturing costs.
These defoaming agents are a new type of functional masterbatch specifically designed to tackle the water bubble issue in plastic products made from materials such as PE, PP, ABS, PS, and nylon. They can be easily added and mixed in small quantities before the plastic molding process, without the need for a drying procedure. This feature offers the advantages of convenience, improved production efficiency, and reduced energy consumption.
The main functions and properties of plastic-defoaming agents:
① Water absorption capability: They can absorb up to 25% of their own weight in moisture.
② Processing performance: They can be used with regular equipment without the need for process modifications.
③ Ideal additive: They are non-toxic, non-irritating, and have good plasticizing properties, without clogging the machinery.
The method of using these plastic defoaming agents is simple – they only need to be directly mixed evenly with the damp plastic raw materials before the production of the desired items. The recommended dosage varies based on the moisture content and needs of the specific plastic being used. For blow molding, the recommended dosage is 1.0% to 2.0%, while for sheet and injection molding, it ranges from 2% to 5%. The exact proportion should be determined by the user according to the moisture level of the plastic.
Application of defoamer:
Plastic defoaming agents find wide applications in various fields, including film products, bag products, sheet products, and injection-molded products. Common thermoplastic polyolefins such as PP, LDPE, HDPE, LLDPE, EVA, PVC, biodegradable plastics, and recycled plastics can all benefit from the use of these masterbatches. Examples of products that can be produced using this technology include book covers, cutlery, sheets, pipes, profiles, extrusion, injection molding, and calendaring. These masterbatches exhibit excellent compatibility with these plastics and can be well blended with inorganic or organic fillers added to the plastic formulations.
When using these masterbatches, a few points should be kept in mind:
① Avoid exposure to moisture before use.
② It is recommended to use the masterbatch immediately after preparation.
③ Avoid heating and drying the masterbatch with damp plastic as it may affect the quality of the final product.
④ Check the packaging for any damage before opening, and seal any unused masterbatch as soon as possible.
Plastic defoaming agents offer a practical solution to moisture-related issues in plastic production, contributing to improved end-product quality and cost efficiency.
12. Laser Marking Additives
A plastic laser marking additive is a substance that is added to plastic materials to enhance their ability to be marked or engraved using laser technology. It is specifically designed to improve the contrast and durability of laser markings on plastic surfaces.
The process of laser marking involves using a high-powered laser beam to create a permanent mark on the surface of a material. However, plastics are generally difficult to mark using lasers due to their low absorption of laser energy. This is where laser marking additives come into play.
Laser marking additives work by increasing the absorption of laser energy by the plastic material. They contain special pigments or dyes that are capable of absorbing the laser wavelength, converting it into heat energy. This heat energy then helps to create a contrast between the marked area and the surrounding plastic surface.
Laser marking additives offer several benefits in the plastics industry.
① Firstly, they allow for high-contrast, permanent marking of plastic products, which is important for product identification and traceability. This is especially useful in industries such as medical devices and electronics.
② Secondly, laser marking additives can be added to plastic materials without affecting their physical properties, such as strength and durability.
③ Thirdly, laser marking is a non-contact process, which means that it does not cause any damage to the plastic surface, resulting in a high-quality, precise mark.
④ Additionally, laser marking is a fast and efficient process that can be easily automated, reducing production time and costs.
⑤ Finally, laser marking is an environmentally friendly process that does not produce any harmful emissions or waste, making it a sustainable option for plastic marking.
The application of laser marking additives is widespread across various industries.
It is commonly used in the automotive, electronics, medical, and packaging sectors. Laser marking additives are utilized in various industries for marking different components.
- Automobile industry, they are used to mark items like dashboards, buttons, and switches.
- Electronics industry, they are employed to mark circuit boards and other electronic parts.
- Medical field, laser marking additives are utilized for marking surgical instruments and medical devices.
- Lastly, in the packaging industry, they are used to mark product labels, barcodes, and other packaging materials.
DOME Materials is a leading manufacturer of laser marking additives in China.
With their expertise and advanced technology, they provide high-quality additives that meet the specific requirements of different industries. Their additives are designed to ensure clear, precise, and long-lasting laser markings on plastic surfaces.
Conclusion:
When it comes to selecting polymer additives, careful consideration must be given to ensure optimal performance. Polymer additives play a crucial role in enhancing the properties and functionality of polymers, such as improving their durability, flame resistance, or UV stability. The selection process involves evaluating various factors, including the specific application requirements, desired performance enhancements, and compatibility with the base polymer. Thorough research and testing are necessary to identify the most suitable additives that will effectively meet the desired goals and deliver the desired results.
