All kinds of barrier materials (2)

Acrylonitrile resin (AMA)

This is a transparent rubber modified acrylonitrile material with excellent chemical resistance, gas barrier properties and high modulus or stiffness, mainly used for packaging. The permeability of AMA depends on the presence of additives, as well as the chemical composition of acrylonitrile and comonomers. Thermoforming, film extrusion, sheet extrusion, extrusion blow molding, casting, injection molding, injection blow molding, injection stretch blow molding can be used.

Its main route is mainly used for packaging, including food packaging: processed meats, fish, cheese, condiments, sauces, squeezed juices and juice concentrates; pharmaceutical packaging: pharmaceuticals and skin patches; personal care: cosmetic packaging, mouth washes, Perfume and so on.

BP's Barex is this type of product, an acrylonitrile/methyl methacrylate copolymer grafted onto acrylonitrile rubber. Barex 210 and 218 resins are high barrier, impact resistant modified copolymer resins. Barex resins have the lowest oxygen transmission rates compared to the various types of plastics used in single-layer packaging, and their performance tends to exceed that of multi-layer structures containing EVOH and PVDG with lower costs. Encapsulated in beneficial gases such as nitrogen and carbon dioxide for extended shelf life also prevents oxygen from entering the package.

Barex resins are extremely barrier to oxygen at various relative humidities. However, elevated temperatures can affect barrier properties. In terms of water vapor barrier properties, Barex resins can be comparable to other plastic packaging materials other than polyolefins. In applications where water repellency requirements are critical, Barex resin's water vapor barrier properties can be enhanced by the orientation or lamination of polyolefins.

Cellulose

Cellulosics are mainly made of cellulose acetate. Cellulose is probably the best-known brand of cellulose film. The cellophane flows through a thin slitting spinneret into a sulfuric acid tank and then forms a thin film. This film is both weak and opaque. It must be further treated with metal or other chemical coatings to produce a transparent, flexible plastic film. This process affects the air and moisture permeability of the film.

The use of cellophane films includes tapes, labels, photographic film, paper, glass, and plastic overlays. Uses in the medical field include dialysis membranes. Cellophane is the most commonly used food packaging material after paper and cardboard. More than 50% of kink wrap candies use this film.

Fluorinated polymer

This is a paraffinic thermoplastic polymer in which hydrogen is partially or completely replaced by fluorine. As a result, perfluorinated polymers such as PTFE, FEP, MFA, and PFA, and partially fluorinated polymers such as ECTFE, PCTFE, ETFE, and PVDF are formed. By changing the fluorine content of the polymer, the mechanical properties and overall costs can be comprehensively adjusted according to the end use.

Fluorinated polymers are inert to most chemicals and retain their original properties when exposed to high temperatures. The use of glass fibres (eg molybdenum disulfide fillers) for reinforcement can significantly improve their lower mechanical properties and make protective coatings and linings, monofilaments, rods, pipes, wires and cable insulation, pumps , Tubular filters, filter materials, non-woven fibers and composite laminates and other products.

Polyamide (PA)

Members of the nylon family name the repeating amide group [-CO-NH-] as a component of the polymer backbone, in terms of the number of carbon atoms contained in the monomer. If there are two monomers, the polymer will have two numbers, such as: nylon 6/6.

Of all the nylons, nylon 6 has the lowest cost, is used in applications requiring oxygen barrier properties, and has the best gas barrier and aromatic resistance properties, but the worst moisture resistance. Nylon 66 is used for temperature resistance, and nylon 6/66 is used for applications requiring coextrusion compatibility.

Nylon 12 has the best moisture resistance and the worst gas barrier properties. A variety of nylons combine to provide the best solution for a particular application. Nylon film has good barrier properties to a variety of gases, aromas, and flavors, and its weakness is that it is easy to absorb water. Can be extruded, injection molded, blow molded, rotomolded. Nylon 6 is processed by casting or anionic polymerization. By orientation, the intrinsic barrier properties and mechanical properties of the non-oriented nylon film can be improved. After axial orientation, the nylon film can greatly improve the oxygen and aromatic barrier properties.

Typical uses for nylon include automotive parts, electronics/electrical appliances and packaging.

Polyethylene terephthalate (PEN)

PEN can be processed into films, fibers and containers. Compared with OPET, bidirectional PEN film has excellent physical properties. DuPont Teijin PEN film is professionally designed, especially suitable for applications with harsh environmental conditions or requiring special barrier properties, such as labels, laminating materials, circuits, and unplugging, as well as industrial, general purpose, and high value-added applications.

Thermoformed and blow molded containers have excellent gas barrier and moisture proof properties compared to containers made from PET homopolymers, and their oxygen barrier performance is five times that of PET.

Liquid Crystal Polymer (LCP)

Liquid crystal polymer (LCP) resins are high-crystalline, heat-type (melt-oriented) thermoplastics, including glass/mineral-reinforced grades and specialty grades.

LCP can be processed with conventional thin-film equipment to produce a uniform, pinhole-free, highly transparent barrier layer. This type of resin is generally used as the second to fifth microlayers in a multilayer film. Under the same oxygen barrier performance (relative humidity of 90%), the thickness is only 1/10 of that of the EVOH-based film. LCP is bidirectional and thermoformable.

Ticona Vectran LCP has excellent barrier properties that prevent the penetration of oxygen, water vapor, carbon dioxide, flavors and aromas. Vectran produces a high degree of orientation during the production of blown and cast films, resulting in higher barrier properties and modulus in a variety of film structures. Vectran LCP has the lowest oxygen permeability compared to various general-purpose barrier films, especially in high humidity environments.
Vectran maintains barrier properties when relative humidity rises, and is no exception when relative humidity exceeds 80%. Vectran LCP hardly absorbs the taste of chemicals such as d-limonene. During the cooking process, the relative humidity reached 100%, and the oxygen barrier properties of the Vectran LCP remained unchanged. Before and after cooking, the material has the same low oxygen permeability. During the cooking process, LCP hardly absorbs any moisture, so when the pressure is released after the processing is completed, the structural integrity of the laminate can be ensured.

In general, LCP can be used for connectors, optical fiber cables, circuit boards and other electronic appliances; medical products such as disinfecting plates, dental equipment and surgical instruments; industrial and consumer products such as printers, fax machine parts, and commercial machine housings; pumps and meters Chemical processing industries such as valves and valves; and high barrier cooking bags such as stand-up pouches, lids, and trays.

Polyethylene terephthalate (PET)

PET is a water-white polymer. DuPont Teijin Melinex Film Co., Ltd. is a bidirectional polyester film. Its Melinex 813 film is highly transparent and has excellent handling characteristics in metallization. After the aluminum metallization treatment, the film has a beautiful appearance and shows the best oxygen barrier performance and moisture resistance performance compared with other flexible packaging films.

The single largest application area for PET containers is carbonated soft drink bottles and water bottles. No additional barrier protection is required for both applications, and PET base plastics performance is satisfactory.

In addition, DuPont has Selar PT products, including the 4000 series: single-layer and co-extrusion heat-sealing films for metallization, lamination, and oven trays; 5000 Series: Solvent-barrier containers for non-food applications; 7000 Series: sheet, extrusion overlay, and film; 8000 Series: Thermoformed transparent containers, blister pack extrusion blow molded bottles, and coextruded sheets for heat sealing.

PET has excellent barrier properties to oxygen, carbon dioxide, and water vapor. The barrier ranges are 0.6 to 0.8, 3 to 5, and 2.5 to 5.0 mol/(m.s.Pa) x 10 to 17 respectively. The temperature and relative humidity were 23°C and 50%, respectively.

Polystyrene (PS)

Polystyrene (PS) resin families include general-purpose PS, crystalline PS, oriented and foamed crystalline PS, modified and impact resistant PS, and high-impact PS. Universal PS is usually the lowest cost.

In some applications, it is best to increase the barrier properties of polystyrene (to reduce the permeability). Therefore, the PS film or sheet can be veneered with vinylidene chloride copolymer latex. The film can be used directly and the sheet can be thermoformed. Typical products are disposable jelly containers.

At the same time, multilayer sheets can also be made by co-extrusion. In this structure, high impact polystyrene (HIPS) provides structural strength and thermoformability. The vinylidene chloride copolymer enhances the oxygen barrier property and the moisture resistance, thereby producing a food container having a strong structure and excellent barrier properties. The permeation of a multilayer film can be regarded as a certain penetration of a monolayer film.

The oxygen permeability of styrene polymers slowly decreases as the temperature decreases. This is a typical characteristic of the polymer below the glass transition temperature (Tg). For water vapor barriers, a slight increase in temperature also increases water vapor infiltration.

PS is generally used in cheese, butter, meat trays, cardboard egg trays, fruit trays, cakes and other packaging; and disposable medical packaging, biscuit packaging and large / small electrical packaging.

Acrylonitrile/butadiene/styrene (ABS)

ABS copolymers contain a variety of resins, with various resins typically consisting of more than 50% styrene and varying levels of acrylonitrile and butadiene. The three components are combined by different means such as polymerization, agglomerate copolymerization, and physical mixing.

GE's Cycolac contains an elastomer and an amorphous thermoplastic component. The elastomer component is generally a polybutadiene or butadiene copolymer.

ABS can be used in medical equipment, cosmetics, household products, automotive and commercial equipment and other products.

Polyvinyl chloride (PVC)

Gas vinyl chloride produces polyvinyl chloride (PVC) by polymerization. As the most widely used plastic material in the world, PVC itself is hard, brittle, and difficult to process. The addition of plasticizers and other additives can enhance the flexibility and functionality of the compound. PVC can be used as both a rigid compound and a plasticizer to produce a soft grade product. Plastisols are the result of the dispersion of superfine particulate PVG resin (dispersion grade) in liquid plasticizers. Diluent plasticizers are products formed by plastisols and volatile diluents or solvents. Commercial PVC copolymers include grades produced from the polymerization of vinyl acetate, vinylidene chloride, marjoram, and fumarate.

The packaging market is the main market for PVC. Rigid grade PVC can be blown into bottles or sheeted and made into thermoformed boxes and blister packs. Flexible PVC compound has the characteristics of high strength, high transparency, easy processing, low raw material cost, and is often used in food packaging. Other major markets for PVC include construction, consumer products, utilities, electronics, and other industries.

The use value of PVC lies in its vapor permeability and anti-condensation characteristics. Rigid PVC has a tight packing and semi-crystalline structure