What is the composition of co-extruded barrier laminated films?

Nanjing Suminoe Precision Co-extruded barrier composite films are usually made up of a combination of barrier plastics, polyolefin plastics (moisture-proof plastics, generally also used as heat-sealing layers) and adhesive resins, which are described as follows.

First, the barrier resin

At present, the total extrusion of composite films with barrier resins, mainly nylon 6 and EVOH resin, the former used in the production of ordinary barrier and puncture-resistant barrier film, the latter used in the production of high barrier film. www.susumino.com南京住野精工专业淋膜复合机研发生产

1. Nylon (PA)

Used in the manufacture of barrier co-extruded composite film nylon is mainly nylon 6, in addition to aromatic nylon MXD6, but because of the latter is expensive, the actual application is not common.

(1) The main characteristics of nylon 6

Has a good barrier to oxygen, carbon dioxide and other gases through the performance, belongs to the so-called barrier materials, see Table 2-1; puncture resistance is outstanding; oil resistance, good resistance to organic solvents; good resistance to high and low temperatures, can be resistant to high temperatures of more than 135 ℃ cooking; health performance is good, can be used for food, pharmaceutical packaging; nylon has a good molding and processing performance, do not need special processing equipment, production process is also easier to master. Nylon has good moulding and processing performance, does not need special processing equipment, and the production process is easy to master.

(2) Co-extruded barrier layer with nylon 6 representative products

Nylon 6 for co-extruded barrier layer is different from ordinary nylon 6 resin for chemical fibre and engineering plastics, mainly in relatively high molecular weight, high melt strength and good film-forming property. At present, some famous nylon resin manufacturers, are co-extruded composite film with nylon special grade, such as Japan's Mitsubishi Chemical Corporation, the United States of America's Honeywell, Germany's BASF Corporation, and so on.

(3) nylon co-extruded composite film moulding process points

Nylon plastic is hydrophilic plastic, exposed in the air, easy to absorb moisture in the atmosphere and lead to material moisture, and when the moisture content of nylon is greater than 0.1%, that may make the product bubbles, so before the moulding process, generally need to be pre-drying treatment (moisture-proof original packaging is opened for immediate use, can not be pre-drying treatment that is added to the application of the extruder); at high temperatures, the nylon is easier to produce oxidative degradation, in order to prevent the oxidation and degradation of the nylon film. In high temperature, nylon is more prone to oxidative degradation, in order to prevent oxidation and deterioration of nylon drying treatment, can be dried in a vacuum oven (in addition to oven heating and drying, industrial production is also used in boiling heating, microwave heating and other methods of drying of nylon, boiling heating, microwave heating has the advantages of high heating efficiency, heating time is short, but the one-time investment is larger), if the use of ordinary blower box drying The drying temperature is better than 100℃.

Nylon 6 and polyolefin plastic affinity between the poor, in the use of nylon and polyolefin matching the production of co-extruded composite film, adhesive resin must be used to improve the nylon layer and polyolefin layer of the bonding force, otherwise there may be a delamination of the layers of the problem, so that the production of composite film loss of use value.

www.susumino.com南京住野精工专业淋膜复合机研发生产

2. Ethylene vinyl alcohol copolymer (EVOH)

EVOH can be regarded as a copolymer of ethylene and vinyl alcohol according to its molecular structure, which is +CH2-CH2fCH-CH2)m. In EVOH, the content of the ethylene component, OH, is usually in the range of 30% to 50% (molar fraction). Since EVOH is a copolymer structure, its properties change accordingly with the different contents of ethylene and vinyl alcohol. As the ethylene content increases, the barrier to non-polar gases (oxygen, carbon dioxide, ammonia, etc.) decreases while the moulding and processing properties and moisture resistance improve accordingly.

The characteristics of EVOH are as follows.

www.susumino.com南京住野精工专业淋膜复合机研发生产

(1) Main Advantages

Barrier oxygen and other non-polar gases through the performance is particularly good; has outstanding fragrance retention; health performance is excellent, can be used for food, pharmaceutical packaging; oil resistance, resistance to organic solvents performance is superb; has good transparency and gloss; printing performance is excellent; environmental protection adaptability is good, the waste can be melted regeneration processing, combustion processing and recovery of heat energy does not produce environmentally hazardous poisonous, hazardous substances; moulding performance is excellent. Excellent performance, can be applied to general-purpose plastic moulding equipment for processing.

(2)Main disadvantages

Expensive, EVOH price is not only much higher than ordinary polyolefin plastics, and more expensive than the price of nylon 6; heat resistance is limited, even if the cooking grade EVOH, made of co-extruded composite film, the highest can only withstand 121 ℃ high temperature cooking.

(3) EVOH Forming Processing Points

EVOH has certain hygroscopicity, the moisture content of the granule should be controlled below 0.3%, if the material is damp, it must be pre-dried before use, otherwise the product will have defects such as bubbles.EVOH has enough thermal stability, but compared with general-purpose plastics such as polyethylene, EVOH's thermal stability is poor, when the temperature exceeds 230℃, the part of the structure of the ethylene alcohol in EVOH will be rapidly reduced, and it can be used as a composite film. When the temperature exceeds 230℃, the structural part of vinyl alcohol in EVOH will be decomposed rapidly, so the temperature of extrusion moulding must be controlled below 220℃. EVOH stays in the extruder for a long time, it will be gelatinous because of the heat of the resin, which will lead to trouble in operation, so when short-term shutdown is needed in the process of production, it is necessary to add a small amount of lubricant into the EVOH and supply high-viscosity polyolefin resin in order to exclude the EVOH resin in the extruder. When the production process needs to be shut down for a long period of time When the production process requires long-term shutdown, the equipment should be cleaned up immediately after stopping the operation.

Nanjing Suminoe Precision Machinery Co., Ltd. is a collection of scientific research, production, sales in one of the high-tech enterprises, and has always adhered to the integrity, equality, customer interests first business philosophy, in order to better improve the quality of equipment, step into a more professional standardised production track. We set up a plastic sheet plate, casting, bi-directional stretching, non-woven nonwoven meltblown cloth, film composite, renewable granulation environmental protection recycling system and coating machine manufacturing system and other seven categories of equipment, independent research and development technology centre and production departments. We provide professional full set of technical solutions to meet the special needs of each customer. Among them, regarding the extrusion laminating manufacturing system, i.e. film laminator, the following production lines are available for customisation: PE double/triple co-extruded laminating production line, LDPE (3-in-1) laminating production line, PP,PE,PLA double-side laminating production line, aluminium foil high-speed laminating production line, PP spunbonded laminating production line, textile interlining fabrics laminating production line, hot-melt adhesive laminating production line, multi-layer extrusion laminating production line, graphene laminating production line and other laminating equipment. Graphene coated laminating line, Carbon fibre laminating line.