Based on general purpose plastics and engineering plastics through physical, chemical, mechanical and other processing methods such as filling, mixing, reinforcement, etc., to improve performance of plastics or increase functions, fire resistance. , strength and mechanical properties such as impact resistance and toughness are improved and improved, making plastics suitable for special environmental conditions such as electricity, magnetism, light and heat.Scope of plastic modification
Application range of modification technology:
From production of raw resin to production of modified plastic masterbatch of various specifications and grades, it is widely used in raw materials and molding processes of almost all plastic products.
Such as plasticity, transparency, density, precision, processability, mechanical properties, chemical properties, electromagnetic properties, corrosion resistance, aging resistance, wear resistance, hardness, thermal properties, flame retardancy, barrier properties, etc. To reduce cost of plastic products, improve performance and improve functions, plastic modification technology is inseparable.Common plastic modification methods
1. Fill Modification
By adding inorganic mineral (organic) powder to ordinary plastics, it is possible to improve rigidity, hardness, heat resistance and other properties of plastic materials. There are many types of fillers and their properties are extremely complex. The role of plastic fillers: improve plastic processing performance, improve physical and chemical properties, increase volume and reduce costs.
Requirements for plastic additives: 1. Chemical properties are inactive, inert, will not have side reactions with resins and other additives, 2. Will not affect water resistance, chemical resistance, weather resistance and heat resistance of plastics, etc. 3. Does not reduce physical properties of plastic 4. Can be poured in large quantities 5. The relative density is small, which has little effect on density of product 6. The price is relatively low.
2. Extended Modification
Strengthening measures: by adding fibrous materials such as fiberglass and carbon fiber.
Improvement effect: can greatly improve rigidity, strength, hardness and heat resistance of material,
The unfortunate consequences of modification: many materials can lead to surface deterioration and reduced elongation at break.
1) reinforced material has higher strength and modulus;
2), resin has many excellent physical, chemical properties (corrosion resistance, insulation, radiation resistance, high temperature instant ablation resistance, etc.) and processing properties;
3) After bonding resin with reinforcing material, reinforcing material can improve mechanical or other properties of resin, and resin can bond and transfer load to reinforcing material, so that reinforced plastic has excellent performance. .
3. Tightening modification
Many materials lack toughness and are too brittle. You can improve toughness and low temperature performance of a material by adding higher toughness materials or ultrafine inorganic materials.
Reinforcing Agent: An additive added to a resin to reduce brittleness of a plastic after curing and improve its toughness and elongation. Commonly used hardeners are mainly maleic anhydride grafts: ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), chlorinated polyethylene (CPE), acrylonitrile-butadiene-styrene copolymer (ABS), styrene-butadiene thermoplastic elastomer (SBS); Ethylene propylene diene monomer (EPDM).
4. Flame retardant version
In many industries, such as electronics and automobiles, materials must be flame retardant, but many plastic raw materials have poor fire resistance. Increasing fire resistance can be achieved by adding flame retardants.
Flame Retardants: Also known as flame retardants, flame retardants or flame retardants, functional additives that render combustible polymers fire resistant; most of them are VA (phosphorus), VIIA (bromine, chlorine) and IIIA (antimony, aluminum). group elements. Molybdenum compounds, tin compounds and iron compounds having a smoke suppression effect are also classified as flame retardants and are mainly suitable for plastics that require fire resistance to delay or prevent burning of plastics, especially polymer plastics. It increases ignition time, ignites self-extinguishing and is difficult to ignite. Plastic flame retardant grade: Gradually increase from HB, V-2, V-1, V-0, 5VB to 5VA.
5. Changing weather resistance
Usually refers to frost resistance of plastics at low temperatures. Due to inherent low temperature brittleness of plastics, plastics become brittle at low temperatures. Therefore, for many plastic products used in low temperature conditions, frost resistance is usually required.
Weather resistance: Refers to a series of aging phenomena such as fading, discoloration, cracking, shredding, and reduction in strength of plastic products due to influence of external conditions such as sunlight, temperature changes, wind and rain. UV exposure is a key factor in aging of plastics.
6. Modified Alloy
Plastic Alloy is use of physical mixing or chemical grafting and copolymerization techniques to transform two or more materials into a new material with high performance, functionality and specialization, to improve performance of material or combine it with other materials. , Target with two material properties. It enhances or enhances performance of existing plastics and reduces costs.
General purpose plastic alloys such as PVC, PE, PP, PS alloys are widely used and production technology is generally mastered. Engineering plastic alloys: generally refers to engineering plastic (resin) blends, mainly including mixing systems based on engineering plastics such as PC, PBT, PA, POM (polyoxymethylene), PFO, PTFE (polytetrafluoroethylene), and ABS resin modified materials. The production of PC/ABS alloy is growing at about 10% every year, and its growth rate is leading in field of plastics. At present, PC/ABS alloy research has become a hot spot in polymer alloy research.
Market classification, consumer groups and market application of plastic modification
Main sub-categories, consumer groups and market use of modified plastics.
01. Flame retardant resins
Products made of flame retardant plastic can greatly reduce risk of fire in event of a short circuit, overload, flooding, etc.
02. Reinforced and hardened resin
Mainly divided into weatherproof and hardened special materials of polypropylene, glass fiber reinforced thermoplastics and other products:
1), PP weather-resistant and hardened special material: PP weather-resistant and hardened special material is a new PP material with engineering plastic properties, which has advantages of good low-temperature toughness, small molding shrinkage, high rigidity. , and strong weather resistance., mainly used in outdoor where weather and UV resistance is required. Its main consumer groups include home appliance companies and auto parts companies.
2), glass fiber reinforced thermoplastics: main products: AS/ABS glass fiber reinforced, glass fiber reinforced PP, glass fiber reinforced nylon, PBT/PET glass fiber reinforcedfibre-reinforced PC, glass-fibre reinforced PPE/PPS, glass-fibre reinforced. etc. Its main consumer groups include computer accessory companies, machine parts companies, power tool companies, lighting products companies, etc.
03, plastic alloys
Mainly divided into PC alloy, PVC alloy and polyester alloy. PC alloy product features: high toughness, creep resistance, heat resistance, low water absorption, non-toxic, excellent dielectric properties and so on. PC Alloy Application: Automotive Dashboards, Computer and Office Automation Equipment, Power Tool Cases, Cell Phones, etc. PVC/ABS Alloy: Made from PVC and ABS as a matrix, with addition of thickeners, lubricants, stabilizers, flame retardants, and others modifiers.
Effective advantages: excellent mechanical properties, weather resistance, processing rheological properties, good surface gloss, good injection molding and extrusion effects, and alloy material with excellent economic performance. Scope of application: Can replace flame retardant and weather resistant ABS, polycarbonate, etc., and is used in household appliance enclosures, electric switches, electric meter enclosures, lighting materials, communication networks, building materials, etc. Polyester alloy: It has excellent mechanical properties (fatigue resistance), dimensional stability, chemical resistance, environmental stress cracking resistance and its application range: automobiles, household appliances, power tools and other fields.
04. Functional Masterbatch
Mainly refers to high impact polystyrene, tempered flame retardant color mother liquor. The characteristics of functional dye masterbatches allow not only to reduce production costs, but also to improve product quality.
1), comply with UL94, IEC-65 and GB8898 flame retardant requirements for electrical and electronic products;
2), improve toughness, processing flow and mold release of HIPS resin;
3) Color HIPS resin.
Several kinds of general additives, additives in table are mainly divided into three categories: processing additives, additives with thermodynamic characteristics and functional additives, and then from specific varieties, applicable substrates and functions.
Trends in development of plastics modificationTrends in development of modified plastics
1. Converting conventional plastic to engineering plastic
Conventional plastics are cheap, widely available and of limited use. Ordinary plastics are modified to obtain engineering plastics, which is inevitable for further development of technology. Conventional plastics continue to develop in engineering and occupy some areas of traditional engineering plastics.
2. High performance and specialization of engineering plastics
Engineering plastics have entered high-tech fields through constant modification, such as in automotive, aviation, and military fields. This is also a point of contention for future national strategic competitions.
3. Low cost and popularization and application of special engineering plastics
Special engineering plastics have special properties such as: good electrical properties, high temperature and dimensional stability, fire resistance, radiation resistance, chemical resistance and high mechanical properties. However, price and cost are often too high, and applications are limited. How a low-cost improvement is made determines whether it can enter a wider area of application.