Plastic packaging materials analysis

1. Polypropylene (PP)

Performance characteristics: Polypropylene is the lightest of all common plastics. Its heat resistance is the highest among general-purpose plastics. It can be used at 100 °C ~ 120 °C for a long time. High crystallinity, tensile strength and hardness are better than polyethylene, moisture resistance, water resistance and odor resistance are better, and can be heat sealed. Excellent bending fatigue resistance, can withstand the acid, alkali, salt liquid below 80 ° C and most organic solvents such as polypropylene packaging box to take advantage of this feature. Cold resistance, poor aging resistance, poor air tightness, unsuitable for use at low temperatures, and susceptible to light and oxygen. It must be surface treated before bonding or printing.

Scope of application: Widely used in the production of food, chemical products, cosmetics, food and beverage and other turnover boxes, blow molded bottles for shampoo, cosmetics and other packaging, threaded caps or hinged packaging, woven bags and packaging film, packing tape And foam cushioning materials, etc.

2. Low density polyethylene (LDPE, LLDPE)

Polyethylene is a white waxy solid that is translucent and almost tasteless and non-toxic. The polyethylene macromolecular chain has good flexibility and is easy to crystallize. At normal temperature, the polyethylene is composed of partially crystallized and partially amorphous bodies.

LDPE

Performance characteristics: Low density polyethylene has good processing performance and good transparency, but has poor air tightness, low tensile strength, low heat resistance temperature, chemical resistance and solvent resistance, and high density polymerization. Ethylene, and easily absorbs oil and swells, making the product sticky.

Scope of application: blow molding bottles, squeeze hoses for packaging of condiments, medicines, etc.; container accessories such as bottle caps and stoppers; various packaging films, containers and foam cushioning materials.

LLDPE

Performance characteristics: Impact strength and stress crack resistance are similar to high density polyethylene, while transparency, hardness and processability are between high density and low density polyethylene. Elongation and puncture resistance are among the best of various polyethylenes.

Scope of application: It is especially suitable as a packaging film. Its thickness can be reduced by 20% compared with low-density polyethylene. It is a promising plastic packaging material.

3. High density polyethylene (HDPE)

Performance characteristics: good strength, heat resistance, maximum temperature up to 120 ° C, poor transparency, flexibility and processing properties, poor gas barrier properties, low gloss, surface treatment before printing.

Scope of application: Containers, trays, large barrels for turnover packaging of fresh milk, chemical products, etc. Bottles with yogurt, caps, stoppers and other container accessories.

4, foamed polyethylene - EPE (commonly known as pearl cotton)

Divided into sheet, sheet, pipe, bar and its segmentation shape.

Scope of application: Widely applicable to packaging any shape of goods, especially electronic products such as: computer, TV, audio, speakers and other types of electrical anti-static buffer packaging. EPE is environmentally friendly and features good elasticity and toughness. Life jackets, travel bags, hats, etc. can also be made.

5, polystyrene (PS)

Performance characteristics: colorless and transparent, tasteless and non-toxic, good coloring and printing, low water absorption, good dimensional stability, rigid and non-ductive. Resistant to organic acids, alkalis, salts, lower alcohols and their aqueous solutions, low impact strength, low surface hardness, easy to scratch and sand; moisture resistance, poor heat resistance, susceptible to many hydrocarbons, ketones, higher Fatty Acids, etc. Split and soften.

Scope of application: Widely used in the production of small packaging containers for food, pharmaceuticals and daily necessities, such as boxes, cups, and other films for food packaging. In addition, it is also widely used in the production of foam cushioning materials, etc., for shock-absorbing packaging of instruments, meters, electrical products, etc.

6, polyvinyl chloride (PVC)

Performance characteristics: good rigidity and hardness, poor heat resistance, transparency up to 76% to 82%. It has excellent mechanical strength, wear resistance and pressure resistance, good moisture resistance, water resistance and air tightness, and can be heat sealed. Excellent printing performance and flame retardancy. Resistant to strong acids, strong bases and non-polar solvents, easily eroded by polar organic solvents, containing toxic vinyl chloride monomer, and the plasticizers, stabilizers, etc. used are mostly toxic substances, so they are used in foods and pharmaceuticals. The packaged polyvinyl chloride should be non-toxic, and the content of vinyl chloride monomer should not exceed 1ppm.

Scope of application: production of rigid packaging containers, transparent sheets and flexible packaging films. Polyvinyl chloride transparent sheets are thermoformed into various packaging containers and are widely used for packaging foods and pharmaceuticals. In addition, polyethylene can be made into foam and cushioning materials.

7, polyethylene terephthalate (PET)

Performance characteristics: very good mechanical strength, good hardness, wear resistance and folding resistance, good heat resistance, cold resistance, good moisture resistance, air tightness and excellent odor resistance, weak acid resistance , weak base and most solvents, good oil resistance, suitable for printing, not resistant to strong alkali, strong acid, chlorinated hydrocarbons, etc. It also has an erosive effect; easy to carry static electricity, and there is no proper method to prevent static electricity, heat sealing Poor performance; expensive.

Scope of application: It is mainly used for the production of packaging containers and films. Because of its good air tightness, heat resistance and cold resistance, polyester film is suitable for the packaging of frozen foods and cooked foods. Polyester bottles are used in large quantities for beverage packaging.

8. Polyvinylidene chloride (PVDC)

Performance characteristics

It has a light brown tough material and is highly crystalline. It has very good air tightness and moisture resistance to water vapor and gas. Polyvinylidene chloride has good mechanical strength, can resist strong acid, strong alkali and organic solvent, has excellent oil resistance, self-adhesiveness, is difficult to burn and has self-ignitability, poor aging resistance, is easily affected by ultraviolet rays, and easily decomposes hydrogen. Its monomer is also toxic. Therefore, the quality standards should be strictly controlled for food packaging.

9, polyamide (PA)

Performance characteristics: tough, non-transparent horny material, tasteless and non-toxic, burning charcoal smell when burning.

It has strong crystallinity, high melting point, oil resistance, general solvent resistance and excellent mechanical properties. The expansion strength and impact strength are obviously superior to ordinary plastics, good wear resistance, self-lubricating, high bending fatigue resistance, good low temperature resistance, but poor high temperature stability. It has better air tightness than polyethylene and polypropylene, alkali and dilute acid, no static electricity, and good printing performance. It has strong water absorption and large moisture permeability. It has poor dimensional stability under high temperature conditions, and the airtightness is drastically reduced after water absorption. Nylon is not resistant to formic acid, phenol and alcohol, and concentrated alkali also has an erosive effect.

Scope of application: It is mainly used for soft packaging of foods, especially for the packaging of greasy foods. Nylon containers are also commonly used in packaging such as chemical reagents.

10, polyvinyl alcohol (PVA)

Performance characteristics: Generally, it does not have water resistance, but it can be made water-resistant by heat treatment, aldehyde treatment or cross-linking with molecular chains by using appropriate organic substances. It has good transparency and toughness, tasteless and non-toxic, has excellent air tightness and aroma retention, has good mechanical strength, excellent stress crack resistance, chemical resistance and oil resistance, without static electricity, printing Good performance and heat sealability. It has high water absorption and high moisture permeability, and is easily attacked by solvents such as alcohols and esters.

Scope of application: For food packaging, water-based polyvinyl alcohol can be used for metering and packaging of chemicals.

11. Ethylene-vinyl acetate copolymer (EVA)

Performance characteristics: stress crack resistance, cold resistance, aging resistance and low temperature heat sealing are better than polyethylene, can resist the corrosion of strong alkali and weak acid, the film has poor slip and easy adhesion; the moisture resistance is lower, the density polyethylene is poor. And airtightness is poor; heat resistance is poor; easily eroded by organic solvents such as strong acid, soluble in aromatic hydrocarbons or hydrocarbons; poor oil resistance.

Scope of application: It is used to make packaging film. Because of its good elasticity, it is suitable for wrapping wraps of trays. Due to its excellent low temperature heat sealability, it is often used as a sealing layer for composite films and as a packaging container for pharmaceuticals and foods.

12, polycarbonate (PC)

Performance characteristics: colorless, transparency up to 80% ~ 90%, refractive index is about 1.59, suitable for optical materials, with good moisture resistance and air tightness, excellent aroma retention and heat resistance, cold resistance, outstanding The impact toughness and unnotched impact strength are highest in thermoplastics. It has small molding shrinkage, low water absorption, good dimensional stability, no static electricity, excellent insulation performance, resistance to dilute acid, oxidant, reducing agent, salt, aliphatic hydrocarbons, etc., and good oil resistance. It is easy to produce stress cracking; it has poor bending fatigue resistance; poor heat sealing; it is not resistant to alkali, ketone and aromatic hydrocarbons, and it swells in many organic solvents and causes stress cracking.

Scope of application: It is mainly used for electrical insulation materials. It is mainly used for packaging food in packaging. It has good wear resistance and is suitable for packaging of hardware and sharp objects.

13, polyurethane (PU)

Performance characteristics: excellent elasticity, meet the required density, softness, elongation and compressive strength, good chemical stability, resistance to many solvents and oils, wear resistance 20 times larger than natural sponge, excellent heat insulation, sound insulation , shockproof and bonded, the price is higher.

Scope of application: Shockproof packaging or cushioning cushioning materials for precision instruments, valuable equipment, handicrafts, etc.

14, phenolic plastic (PF)

Performance characteristics: high mechanical strength, wear resistance and excellent electrical insulation performance, high temperature resistance, not easy to deform, resistant to some dilute acid, good oil resistance, poor elasticity, high brittleness, darker color, mostly Black or brown, can not get colorless products, strong base and oxidizing acid can make it decompose, it is slightly toxic.

Scope of application: Widely used as electrical insulation materials. Its application on packaging is mainly used to make caps, boxes and acid-resistant containers for chemical products. The cap made of phenolic plastic can withstand the torque of the capping machine and can keep the seal for a long time without loosening.

15. Urea-formaldehyde plastic (UF)

Performance characteristics: large surface hardness, good gloss and suitable translucency, good coloring, can be made into a variety of good appearance and bright colors, not easy to absorb dust, good electrical insulation, chemical stability, Does not interact with any organic solvent, has excellent grease resistance, poor water resistance, easy to absorb water and deform, can not be disinfected by steam, has little impact strength, and is not resistant to alkali and strong acid.

Scope of application: used to make exquisite packaging boxes, cosmetic containers and caps. When immersed in acetic acid or boiling water at 100 ° C, free toxic substances are precipitated, so it is not suitable for packaging food.

16, melamine plastic (MF)

Performance characteristics: high strength, not easy to deform, smooth and hard surface, ceramic appearance, tasteless, non-toxic, good coloring, can be made into a variety of colorful products. It has good heat resistance and water resistance, and is resistant to boiling water, acid, alkali and grease.

Scope of application: The price is better, it is mostly used to make food containers, and can also be used to make beautiful food packaging containers.

17, PVC shrink film

PVC heat shrinkable film, divided into ordinary packaging film, color printing film.

Ordinary packaging film: suitable for all kinds of product packaging and combination packaging. The product features: good transparency, strong shrinkage and easy operation. The packaged product can be sealed against moisture, insulation, light, strong and beautiful. Color printing film, in addition to various color printing labels, is also suitable for rotary sealing sealing of product bottles and box packaging.

18, POF shrink film

POF shrink bag is environmentally friendly, and has good longitudinal and horizontal shrinkage effects. It is mainly used for shrink packaging of lighter items such as gifts, stationery, and small hardware.

19, PET shrink film

It is an internationally recognized "environmentally friendly" heat shrinkable packaging material produced by "polyester resin slicing". Its technical indicators, physical properties, application range and usage are close to the "PVC" heat shrinkable film.

With the improvement of people's awareness of environmental protection, domestic products are gradually moving towards the needs of the international market. At present, "PET" heat shrinkable film is the most ideal packaging material to replace "PVC".

20, PE shrink film

PE heat shrinkable film is divided into two types: simple type and single type. It is suitable for automatic machine combination packaging of various products. The product features: good toughness, not easy to break, can replace carton packaging.