Moistureproof and Mildewproof Polymer Composite Packaging Material Technology

Moisture-proof and mildew-proof polymer composites are characterized by light weight, softness, chemical resistance, and good thermal properties. Is widely used in chemical products, precision machinery, electronic devices, instrumentation and military products packaging.
1. Moisture protection 1. Technical performance Chemical products such as gunpowder, explosives, propellants, primers and other materials with high moisture absorption are susceptible to moisture deterioration; electronic instruments and core boards, precision machinery, instrumentation, etc. are subject to moisture, rust, or mold. Erosion phenomenon. Basic requirements of moisture-proof packaging According to the provisions of GB5048, according to the characteristics of the packaged products, transportation, storage conditions and storage period, targeted implementation of the national military standard GJB1444-92 or GJB2605-96 moisture-proof technical indicators.
2. Production process
The production process of moisture-proof packaging materials should be designed in a targeted manner according to the inherent characteristics of the polymer film and the moisture-proof mechanism. The BOPP film with high mechanical strength and good moisture resistance is generally used. After vacuum aluminum plating, it is compounded with PVDV (polyvinylidene chloride) emulsion, which is extremely excellent in moisture resistance, and the temperature resistance is obtained. Excellent composite material. The vacuum aluminum plating process is in a high vacuum state, the metal aluminum is heated and melted to evaporation, and aluminum atoms condense on the surface of the polymer material to form a dense barrier layer-aluminum layer. Aluminum plating process requirements: 1 vacuum degree shall not be less than 103Mpa, so as to avoid brown stripes or uneven thickness of the aluminum layer; 2 control the system tension, open the cooling system to avoid tensile deformation of the film by heat; 3 accurate control of the take-up speed ( 250-300m/min), aluminum feeding speed (0.6-1.0m/min2mm aluminum wire) and evaporation boat heating current to obtain better aluminum layer thickness (250-300). Aluminum atoms block the voids in the molecular chain or between the molecular chains, greatly enhancing the water vapor barrier properties of the film. The PVDC emulsion is obtained by emulsion polymerization of vinylidene chloride and acrylic esters. The emulsion coating is applied to the surface of a VMBOPP (aluminum coated polypropylene) film and plasticized to form a high barrier composite film. Coating process requirements: 1 using anionic surfactants to adjust the surface tension of the emulsion at 40dyn/cm2, the amount of diluent should not be too large to prevent poor drying; 2 coating thickness in the range of 2 ~ 3μm, set the infrared dry The source step temperature ensures that the emulsion is fully plasticized and crystallized; 3 Add a small amount of anti-blocking agent to open the cooling system to avoid film adhesion; 4 The curing chamber temperature is designed to be in the range of 40 to 45°C, and the curing time is 36 to 48 hours, so that the crystal is fully cured. , to obtain excellent water vapor barrier properties. The moisture-proof polymer composite material formed through this process has a moisture permeability that satisfies the technical requirements specified in the relevant standards.
Second, anti-fungal attack 1. Technical performance Chemical products, precision machinery, electronic devices, instruments and other parts of the table in the transport, use, storage process, in the appropriate temperature, humidity, nutrients, light, oxygen and other environmental conditions, easily occur Mold infestation. International GB/T4768-95 "Moldproof packaging" stipulates that the anti-mildew packaging grade should be based on the product's anti-mold invasive ability, environmental conditions involved in transportation, storage, package structure, anti-mildew properties of the selected packaging materials, and the results of the mold test And other factors to determine. The mold test was carried out according to the international GB/IEC 485721-95 "Packaging and transportation package anti-mildew test" or the national military standard GJB573A-98305, in the specified temperature, humidity, strains, and test cycle.
2. Production Process Polymer materials must obtain certain mildew-repellent properties, and mold-repellent substances such as phenolic compounds, organic metal compounds, nitrogen-containing compounds, halogen-containing compounds, sulfur-containing compounds, etc., need to be blended with thermoplastic resins in a certain proportion. Ethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) are mixed, and various additives are added. After mixing, granulation, and obtaining a mildewproof tree. The following points need to be noted in the production of this process: 1 The carrier resin should be made of low density polyethylene resin (LDPE) with good moisture resistance, low temperature resistance, easy heat sealing, and chemical resistance; Tin chloride needs to be added to LDPE resin in a certain proportion (20 to 30%); 3 Additives must be added in a certain order, and be well-mixed; 4 additives should be selected for their synergy and melting of the resin. Sex and durability, and adapt to process conditions.
The use of mold-proof resin to produce mold-resisting polymer composite materials often uses a three-layer (ABC) co-extrusion blown film-dry composite production process. The final process is to add the mold-proof resin to the A fabric bucket to extrude. The process requirements: 1 appropriate to reduce the extruder heating temperature in each area, increase the screw speed, increase the number of filter mesh or mesh, to ensure that the solution plasticization is good; 2 choose the right blow ratio, traction ratio: 3B, C fabric bucket Select low density polyethylene resin (LDPE) and linear low density polyethylene resin (LLDPE) resin with high mechanical strength and low slip agent content; 4 pay attention to MI (melt index) of mold proofing resin, LDPE, and LLDPE ) To be as close as possible; 5 this film C surface after corona treatment, wetting should be greater than 38dyn/cm2 wetting tension, and then with the moisture-proof polymer material by dry compounded to obtain moisture-proof mildew polymer composite materials. The design of moisture-proof and mildewproof polymer packaging materials should be based on the technical requirements of the products and the conditions for the growth and development of molds, reasonable selection of packaging materials and packaging technology; strict implementation of moisture-resistant, mildew-resistant standards; strict control of the production and circulation environment, the use of pre-drying, vacuum , Fill with inert gas and seal the package; control the temperature, relative humidity, so that the package to moisture-proof, anti-mildew package level requirements.