Describes the types of plastic bags and raw materials

Plastic bag inside a wide range of common life into plastic bags that jolly fashion , PO material that is done, some still do recycled materials , PO pocketed brittle body , tension is good , it has been used in the shopping bag , vest bag , handbag above , another PO flat pocket also commonly used in electronics, digital products and hardware products , PO normal situation is opaque, can be printed and dyed a variety of colors . The kind of airtight seal tea bag fitted with PE material is made ??of bone bag, PE bone bag is translucent , transparency, more fierce than the PO material soft , good toughness, wide range of applications , in addition to bone bag styles in addition, there are PE flat pockets, along bags, organ bags, bagging and other Quartet , PE material non-toxic , acid, is ideally suited for industrial and agricultural products with a bag. Secondly store common PP self-adhesive bags, plastic case OPP self-adhesive bags, these two types of plastic bags packaging pens, notebooks , stickers, bags commonly doll figure , both of which have a common feature: high transparency , OPP higher brightness than the PP , the difference between : packaging company PP relatively soft, waterlines , OPP relatively rigid , smooth feel , however , no watermarks , high brightness through the bakery is also useful to OPP packaging films and packaging bag.
There are three relatively rare materials : 1, EVA, 2, PPE, 3, CPE. EVA and the PPE is used very little used , the specific areas in which is possible, I do not incompetence , CPE plastic bag is a bag with a matte , opaque material clear plastic box , dark milky white , very soft , feel very comfortable, smooth and normal positive frosted back , because with the CPE packaging is very upscale, with a very good protection , so CPE plastic bags are almost the specified application on the phone , tablet PC , PSP game consoles , batteries , MP3 , MP4 and other electronic digital products above.
Finally revisit what PVC and POF shrink material , PVC, and both have POF shrink film packaging performance , although the same function , but has a very different , PVC transparent primarily in a light blue and white two , PVC very brittle , hard, contracted performance in general , after a very hard through the heat shrink easily tore . POF is transparent white, materials with PVC contrary , very soft , very good shrinkage by heat-shrunk still very soft, non-hardening , high transparency, compare these two types of products are widely used in a variety of boxed product packaging, for example : toys, cosmetics, massage , stationery , playing cards, folders, etc. relative to the outer box shrink bags . Such packaging is primarily plays : Prevent been opened , dust, moisture and other effects, can effectively guarantee your products as new never used , ensure that the product value . However, to the success of such packaging plastic packaging , you must first prepare two kinds of machines , the first one is sealing machine , the plastic box second is shrinking machine . Packaging process is the first product to be wrapped into a box or PVC or POF shrink bag , followed by sealing the shrink bag sealing machine , so well done to shrink without plastics products cracking , seal the mouth and then put the product into the shrinking machine . In this connection, shrink packaging of the product has been completed .

Plastic molding characteristics :

A crystalline material , moisture absorption is small , do not need to fully dry , excellent mobility liquidity pressure-sensitive , high-pressure injection molding when it is appropriate , uniform melt temperature , filling speed , pressure adequately . Should not use direct gate to prevent shrinkage uneven internal stress increases. attention to the selection gate position and prevent shrinkage and deformation.

(2) contraction of the scope and shrinkage, clear direction , easy to deform warping cooling rate should be slow , cold-slug mold design , and a cooling system.

3 heating time not too long, otherwise it will decompose .

4 packaging design soft plastic parts are lighter side of the groove , you can forcibly stripping.

5 melt fracture may occur , not in contact with the organic solvent , to prevent cracking

Polyethylene Products

First, the product categories

Polyethylene (PE general the largest production of synthetic resin species , including low density polyethylene (LDPE Linear low density polyethylene (LLDPE high density polyethylene (HDPE , and some products with special properties .

Second, the chemical properties of polyethylene

Polyethylene has excellent chemical stability , resistance to room temperature, hydrochloric acid, hydrofluoric acid, phosphoric acid, formic acid, amines , sodium hydroxide , potassium hydroxide and other chemicals , nitric acid and sulfuric acid has a strong role in the destruction of polyethylene polyethylene is easy to photo-oxidation , thermal oxidation, ozone decomposition , prone to degradation under the action of ultraviolet light , carbon black of polyethylene has excellent light shielding role of radiation crosslinking may occur after , broken link, to form an unsaturated group , which reflect the .

Third, the physical properties of polyethylene

Polyethylene is a white waxy translucent material , soft and tough , lighter than water , non-toxic , has excellent dielectric properties. Flammable and away from the fire continued to burn . Permeable low organic vapor transmission rate is greater clamshell packaging polyethylene transparency decreased with the increase of crystallinity in a certain degree of crystallinity , the transparency, and increased with the increase in molecular weight high density polyethylene melting point range of 132-135oC low melting point low density polyethylene (112oC and a wide range.

Room temperature, soluble in any known solvent , 70oC above was dissolved in a small amount of toluene , amyl acetate , a solvent such as ethylene three rate

Fourth, the use of various types of polyethylene products

LDPE : film products used in more than half , followed by pipes, injection molded products, wire wrapping layer

Low , the pressure polyethylene : the injection molding products and hollow products mainly.

High pressure polyethylene : Because ultra high molecular weight polyethylene excellent performance , can be used as engineering plastics .

The temperature of 140 degrees Celsius

Melting enthalpy 292.88J / g

Plastic raw materials :

PE (Polyethylene, PE referred to as PE ethylene addition polymerization of the polymer compounds . Polyethylene is recognized as the world ‘s best materials in contact with food . Toxic, tasteless , odorless, meet food packaging hygiene standards. Polyethylene film , light and transparent , with moisture , oxidation , acid, alkali, tightness in general, excellent sealing properties. largest amount of plastic packaging and printing , the most important material . bags

PVC – Polyvinyl Chloride

PVC referred to as PVC formula (CH2 CH2 n, the most important one vinyl polymer class , currently the world ‘s second largest after the polyethylene plastic varieties .

Shrinkfilm – Shrink Films

Shrink film (Shrinkfilm, one kind in the production process are stretched orientation process by the use of hot air or infrared radiation treatment will shrink thermoplastic film after heat treatment , the film to wrap the object to be packed , the contractile force cooling stage reaches its maximum , and long-term preservation.

HDPE – high density polyethylene

High density polyethylene, low-pressure polymerization referred HDPE , so called low-pressure polyethylene. Milky white , indicating that the luster is poor. Processing films available and T -die extrusion blow molding processes. plastic trays Heat resistant to cooking , cold resistance to freezing , moisture, air , isolated properties, not easy to damage, twice the strength of LDPE . easy opening .

LDPE – low density polyethylene

Low-density polyethylene, LDPE countries referred plastic packaging to in the amount of plastic packaging printing industry ‘s largest variety. Specific gravity of 0.92 0.93 able to float on water . Crystallinity lower ( 60% Pressure 1000 3000kg / C O for bulk polymerization , so called high-pressure polyethylene. 23 degrees Celsius, the density of about 0.92 . suitable for food packaging , fiber products packaging , cosmetic packaging.

BOPP – Biaxially Oriented Polypropylene Film

Biaxially oriented polypropylene film , also known as biaxially oriented polypropylene film , BOPP abbreviation code which is characterized by stretching molecular orientation , mechanical strength , fold strength, gas density , moisture barrier properties than ordinary plastic film in units compared area and cellophane , cellophane price lower than a result of this film excellent in transparency , particularly in India bright and beautiful color reproduction , an important plastic composite flexible packaging substrates .

Plastic bags toxicity identification

More commonly used as food packaging bags made ??of polyethylene film , the film is non-toxic , it can be used to hold food . There is also a film made ??of PVC , polyvinyl chloride itself is non-toxic , but according to the purpose of the film adding additives are often harmful substances, with a certain toxicity , so this type of film , and the film made ??from the plastic bags are not suitable for containing food , such as to identify PVC plastic and polyethylene bags , available The following simple method of identification .

PVC film ( generally toxic )

If you do not add pigment, plastic package is transparent, the surface feels somewhat tacky , forced jitter, low voice , easy to burn a fire from the flame is extinguished , the flame was green , such as : PVC

Poyethylene film ( non-toxic )

Thin milky white , translucent (several laminated observation is particularly evident ) feels relatively smooth , if coated with a wax layer, a hard shake , crisp sound , fire flammable, flame yellow mucus dripping when burning , and there is the smell of burning candles , such as : PE

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