Plastic dishes - be careful! Values ​​PP, PS, PET, PEHD. Marking

This trend is due to several advantages of PP. For example, compared to PET, PP is cheaper, lighter, more resistant to high temperatures during hot packaging and less permeable to moisture. New clarified grades of PP have transparency and gloss comparable to those of PET.
On the other hand, PP bottles generally require a longer production cycle than PET bottles. PP also has a smaller processing temperature range than PET. The gas barrier parameters of PP are not as high as those of PET, and PP is also inferior to PET in rigidity. But manufacturers of polypropylene resins and additives introduced into them make great success in overcoming these shortcomings.

Application
Although PP itself costs less than PET, this cost advantage can be significantly reduced by the need to introduce additives, additional processing steps, or additional barrier layers to make PP competitive with PET. But for a range of applications, PP is still a more economical packaging choice than PET.
PP has not replaced PET as a bottle material for the carbonated beverage industry due to its relative permeability to carbon dioxide. But in the packaging of water, hot-fill fruit juices, iced tea and sports drinks, PP blow molded bottles are becoming increasingly common. PP bottles are also becoming more and more common packaging for sauces, dressings, fillings and other ready-made food products, as well as for detergents and cleaning agents. The most promising area for expanding the use of PP is considered to be wide-mouth food containers.

Rice. 1. Clear PP water bottles (left) are a cost-effective alternative to PET bottles (right).

Comparison of properties
Manufacturers estimate that PP bottles cost 10-30% less than comparable PET bottles. Polypropylene has a lower density than polyethylene terephthalate (0.9 g/cm3 versus 1.35 g/cm3), so PP bottles are lighter than PET bottles. PP bottles can be hot-packed at temperatures up to 100°C, and it is at these temperatures that fruit juices and syrups are packaged. Conventional PET bottles, on the other hand, cannot withstand filling temperatures that exceed the glass transition temperature of PET, which is 76°C. (However, some carried out in lately Improvements in technology have made it possible to increase the filling temperatures of PET containers).

Rice. 2. Bottles made from random PP copolymer can be used for hot filling at temperatures up to 100°C without any permanent deformation.

PP is five times more moisture resistant than PET, but PP is about 30 times more permeable to gases such as oxygen and carbon dioxide. For this reason, a PP bottle, which must prevent gases from entering or escaping from the container, may require a barrier layer that a PET bottle would not need.
In its pure state, PP is less transparent than PET. As a result, brightening agents must be added to PP in order for it to achieve the transparency of PET. PP has a lower thermal conductivity than PET, so PP takes longer to heat up and cool down during processing. As a result, the duration production cycle for PP bottles can be 25% more than for PET bottles. Additives called site initiators can accelerate crystal formation in PCB during cooling, thereby shortening the production cycle and sometimes also increasing clarity.
PP bottles must be processed within a temperature range of only 3-5°C; when using PET the range is 10-15C°. In the production of stretch blow molded bottles, the equipment required for PP preforming production lines is often less expensive than comparable PET production equipment.

Manufacturing technology
For the production of polypropylene bottles for packaging products such as: ketchup, sauces, detergents, mineral water, food and beverages - the extrusion blow molding method can be used.

Rice. 3. The PP bottle produced by extrusion blow molding is equipped with a handle, which cannot be produced using the standard bottle production technology - PET oriented blow molding method.

Oriented blow molding bottle production is commonly used to make PP bottles for water, pharmaceuticals, dehydrated food and spices, household detergents, isotonic and sports drinks, baby food, household supplies, liquid soap and washing powders.

Clarifying agents and crystallization nuclei
Brightening agents are additives to PP, which act as crystallization nuclei special type. Nucleators are additives that increase the rate of polymer crystallization as it cools. This speeds up the cooling of the polymer, thereby reducing the duration of the production cycle; The elastic modulus of the polymer also improves. Brightening agents are crystallization nuclei; they cause the polymer to form spherulites (microscopic sections of crystalline structures formed upon cooling), which are less than the wavelength of the visible part of the spectrum. Because of this, the polymer scatters light less than usual, resulting in a high degree of transparency. Some - but not all - commercial nucleators also have a brightening effect.
Brightening agents are usually organic compounds, such as sorbitol derivatives, which are soluble in thermoplastic melts. Crystallization nuclei, which are usually insoluble in molten polymers, are composed of materials such as talc, salts carboxylic acids or phosphoric acid esters.
There have been several generations of bleaching agents. Dibenzylidene sorbitol, introduced in the mid-seventies, is still widely used. Its use, however, has some limitations, such as lack of transparency under certain conditions and contamination under high temperatures. Other sorbitol derivatives were put into production to solve these problems, but they exhibited undesirable organoleptic properties (taste and odor).

Rice. 4. The latest generation of fining agents (Millad 3988) provide significantly greater turbidity reduction than its predecessor, dibenzylidene sorbitol, DBS.

According to the developers of sorbitol-based clarifiers, which have recently been introduced into production, their substances are free from organoleptic problems. One such supplement is Millad 3988 from Milliken & Company. The greatest reduction in turbidity in polypropylene for this clarifying agent is achieved in the concentration range of 0.24-0.35%. Thermogravimetric analysis shows that the additive is resistant to temperature regime processing up to 370°C, compared to 325°C for the dibenzylidene sorbitol additive. The product, which also acts as a nucleator, reportedly reduces molding cycle times by 5-20%, which may help make PP more competitive than PET in process economics.

Rice. 5. Dependence of the degree of turbidity on the concentration of the clarifying agent. Increasing the concentration of the fining agent reduces the turbidity and variability in PP clarity until optimal level additive content.

In general, PP random copolymers exhibit lower turbidity than homopolymers at the same fining agent concentrations. But PP homopolymers made with metallocene catalysts have the same transparency as PP random copolymers made with a Ziegler-Natta catalyst.

Improving barrier properties
Another way to increase the competitiveness of PP compared to PET in the production of bottles using blow molding is to reduce the gas permeability of PP. This is accomplished by using stretch blow molding to produce bottles from a three-layer structure consisting of two layers of PP on the outside and an ethylene vinyl alcohol copolymer (EVOH) barrier layer on the inside. In terms of cost, such bottles can compete with glass and PET containers when used for packaging many food products and drinks.

Rice. 6. Multilayer blow molded ketchup bottles have improved barrier properties with PP outer layers and EVOH inner layers.

Another approach to the problem of improving the barrier properties of PP is the use of special coatings. One such material is an amino epoxy coating, which is sprayed onto the outside of the bottle and then hot vulcanized. The material, marketed by PPG Industries under the name Bairocade, reportedly significantly improves the oxygen barrier properties of bottle plastics, PET, PP, or other polyolefins.

Increasing the strength of PP
Polypropylene bottles are generally less resistant to drop impact than PET bottles at refrigeration temperatures and freezers, and even with room temperature if the bottle large size. Research has shown that blending clarified PP random copolymer with approximately 15% plastomer (ethylene/alpha-olefin copolymer made with a metallocene catalyst) can significantly improve the drop resistance properties of PP bottles. In one standard test reported by ExxonMobil researchers, a bottle made from clarified PP-plastomer random copolymer had significantly better drop impact performance (2.4 m height) than a bottle made from pure PP random polymer (1, 4 m).

While it seems unlikely that polypropylene will completely replace PET in carbonated drink bottles, there are many other applications where blow molded bottles can be used. At the same time, lower costs and lower weight of PP allow it to effectively compete with PET. Such applications include containers for food, beverages, detergents and other products. Many of the original disadvantages of PP compared to PET - less transparency, longer processing cycles, greater gas permeability and lower impact resistance - have been overcome by the use of brightening agents and nucleators, the use of barrier layers obtained using metallocene catalysts. Further improvement of the properties of PP will allow it to penetrate new markets.

Films for heat treatment

In terms of their many properties and characteristics, lavsan-polypropylene films, or PET/CPP films, are in many ways similar to films of the PET/PE type. However, there are a number of significant differences that influence the customer’s choice of one or another type of product that Megaflex LLC offers to purchase.

So, what are the advantageous features of Dacron-polypropylene films?

• Transparency. High level optical properties;
• Possibility of successful weldability with polypropylene (tray);
• Possibility to pasteurize and sterilize the packaged product

Thanks to all these properties, lavsan-polypropylene film is widely used in such areas of application as:

• Sealing of polypropylene trays (makes it possible to use less expensive non-laminated trays);
• Production of packaging products for sterilization of food and medical products;
• Production of packaging with a high degree of transparency.

Products of Megaflex LLC

Our company, having professionally mastered various mechanisms for the production of high-quality packaging materials, offers its customers to purchase lavsan-polypropylene films of two types:

1.In a transparent version;

2.With interlayer printing (rotogravure, flexographic)

3. Metallized and foil materials for sterilization

Also finished product can be additionally equipped with elements that facilitate easy opening of the package. The thickness of the films can be made based on your wishes, while the standard widths are the following parameters:

1. PET/CPP film – up to 1200 millimeters;

2.PET/BOPP – up to 1,300 millimeters.

The lamination effect gives lavsan-polypropylene films a high level of strength and weldability, which distinguishes them from single-layer materials. However, the degree of elasticity of such materials decreases. Consequently, the consumer, when ordering this or that type of product, must clearly understand the purposes for which the material will be used and set priorities for himself regarding the properties that the product should have.

If you are in doubt about which option may be ideal for you, consult with the specialists of Megaflex LLC, who will share useful tips and give competent recommendations.

This trend is due to several advantages of PP. For example, compared to PET, PP is cheaper, lighter, more resistant to high temperatures during hot packaging and less permeable to moisture. New clarified grades of PP have transparency and gloss comparable to those of PET.
On the other hand, PP bottles generally require a longer production cycle than PET bottles. PP also has a smaller processing temperature range than PET. The gas barrier parameters of PP are not as high as those of PET, and PP is also inferior to PET in rigidity. But manufacturers of polypropylene resins and additives introduced into them are making great strides in overcoming these shortcomings.

Application
Although PP itself costs less than PET, this cost advantage can be significantly reduced by the need to introduce additives, additional processing steps, or additional barrier layers to make PP competitive with PET. But for a range of applications, PP is still a more economical packaging choice than PET.
PP has not replaced PET as a bottle material for the carbonated beverage industry due to its relative permeability to carbon dioxide. But in the packaging of water, hot-fill fruit juices, iced tea and sports drinks, PP blow molded bottles are becoming increasingly common. PP bottles are also becoming increasingly common packaging for sauces, dressings, toppings and other prepared foods, as well as detergents and cleaning agents. The most promising area for expanding the use of PP is considered to be wide-mouth food containers.

Rice. 1. Clear PP water bottles (left) are a cost-effective alternative to PET bottles (right).

Comparison of properties
Manufacturers estimate that PP bottles cost 10-30% less than comparable PET bottles. Polypropylene has a lower density than polyethylene terephthalate (0.9 g/cm3 versus 1.35 g/cm3), so PP bottles are lighter than PET bottles. PP bottles can be hot-packed at temperatures up to 100°C, and it is at these temperatures that fruit juices and syrups are packaged. Conventional PET bottles, on the other hand, cannot withstand filling temperatures that exceed the glass transition temperature of PET, which is 76°C. (However, some recent improvements in technology have made it possible to increase filling temperatures for PET containers.)

Rice. 2. Bottles made from random PP copolymer can be used for hot filling at temperatures up to 100°C without any permanent deformation.

PP is five times more moisture resistant than PET, but PP is about 30 times more permeable to gases such as oxygen and carbon dioxide. For this reason, a PP bottle, which must prevent gases from entering or escaping from the container, may require a barrier layer that a PET bottle would not need.
In its pure state, PP is less transparent than PET. As a result, clarifiers must be added to PP in order for it to achieve the transparency of PET. PP has a lower thermal conductivity than PET, so PP takes longer to heat up and cool down during processing. As a result, the production cycle time for PP bottles can be 25% longer than for PET bottles. Additives called site initiators can accelerate crystal formation in PCB during cooling, thereby shortening the production cycle and sometimes also increasing clarity.
PP bottles must be processed within a temperature range of only 3-5°C; when using PET the range is 10-15C°. In the production of stretch blow molded bottles, the equipment required for PP preforming production lines is often less expensive than comparable PET production equipment.

Manufacturing technology
For the production of polypropylene bottles for packaging products such as ketchup, sauces, detergents, mineral water, food and drinks, the extrusion blow molding method can be used.

Rice. 3. The PP bottle produced by extrusion blow molding is equipped with a handle, which cannot be produced using the standard bottle production technology - PET oriented blow molding method.

Oriented blow molding bottle manufacturing is commonly used to make PP bottles for water, pharmaceuticals, dehydrated food and spices, household detergents, isotonic and sports drinks, baby food, household supplies, liquid soap and laundry detergents.

Clarifying agents and crystallization nuclei
Clarifying agents are additives to PP, which are nuclei of a special type of crystallization. Nucleators are additives that increase the rate of polymer crystallization as it cools. This speeds up the cooling of the polymer, thereby reducing the duration of the production cycle; The elastic modulus of the polymer also improves. Brightening agents are crystallization nuclei; they cause the polymer to form spherulites (microscopic sections of crystalline structures formed upon cooling), which are less than the wavelength of the visible part of the spectrum. Because of this, the polymer scatters light less than usual, resulting in a high degree of transparency. Some - but not all - commercial nucleators also have a brightening effect.
Clarifiers are usually organic compounds, such as sorbitol derivatives, that are soluble in thermoplastic melts. Crystallization nuclei, which are usually insoluble in molten polymers, are composed of materials such as talc, salts of carboxylic acids or phosphoric acid esters.
There have been several generations of bleaching agents. Dibenzylidene sorbitol, introduced in the mid-seventies, is still widely used. Its use, however, has some limitations, such as lack of transparency under certain conditions and fouling at high temperatures. Other sorbitol derivatives were put into production to solve these problems, but they exhibited undesirable organoleptic properties (taste and odor).

Rice. 4. The latest generation of fining agents (Millad 3988) provide significantly greater turbidity reduction than its predecessor, dibenzylidene sorbitol, DBS.

According to the developers of sorbitol-based clarifiers, which have recently been introduced into production, their substances are free from organoleptic problems. One such supplement is Millad 3988 from Milliken & Company. The greatest reduction in turbidity in polypropylene for this clarifying agent is achieved in the concentration range of 0.24-0.35%. Thermogravimetric analysis shows that the additive is resistant to processing temperatures up to 370°C, compared to 325°C for the dibenzylidene sorbitol additive. The product, which also acts as a nucleator, reportedly reduces molding cycle times by 5-20%, which may help make PP more competitive than PET in process economics.

Rice. 5. Dependence of the degree of turbidity on the concentration of the clarifying agent. Increasing the concentration of bleaching agent reduces the turbidity and variability in PP clarity until the optimal additive level is achieved.

In general, PP random copolymers exhibit lower turbidity than homopolymers at the same fining agent concentrations. But PP homopolymers made with metallocene catalysts have the same transparency as PP random copolymers made with a Ziegler-Natta catalyst.

Improving barrier properties
Another way to increase the competitiveness of PP compared to PET in the production of bottles using blow molding is to reduce the gas permeability of PP. This is accomplished by using stretch blow molding to produce bottles from a three-layer structure consisting of two layers of PP on the outside and an ethylene vinyl alcohol copolymer (EVOH) barrier layer on the inside. In terms of cost, such bottles can compete with glass and PET containers when used for packaging many food products and drinks.

Rice. 6. Multilayer blow molded ketchup bottles have improved barrier properties with PP outer layers and EVOH inner layers.

Another approach to the problem of improving the barrier properties of PP is the use of special coatings. One such material is an amino epoxy coating, which is sprayed onto the outside of the bottle and then hot vulcanized. The material, marketed by PPG Industries under the name Bairocade, reportedly significantly improves the oxygen barrier properties of bottle plastics, PET, PP, or other polyolefins.

Increasing the strength of PP
Polypropylene bottles are generally less drop resistant than PET bottles at refrigeration and freezer temperatures, and even at room temperature if the bottle is large. Research has shown that blending clarified PP random copolymer with approximately 15% plastomer (ethylene/alpha-olefin copolymer made with a metallocene catalyst) can significantly improve the drop resistance properties of PP bottles. In one standard test reported by ExxonMobil researchers, a bottle made from clarified PP-plastomer random copolymer had significantly better drop impact performance (2.4 m height) than a bottle made from pure PP random polymer (1, 4 m).

While it seems unlikely that polypropylene will completely replace PET in carbonated drink bottles, there are many other applications where blow molded bottles can be used. At the same time, lower costs and lower weight of PP allow it to effectively compete with PET. Such applications include containers for food, beverages, detergents and other products. Many of the original disadvantages of PP compared to PET - less transparency, longer processing cycles, greater gas permeability and lower impact resistance - have been overcome by the use of brightening agents and nucleators, the use of barrier layers obtained using metallocene catalysts. Further improvement of the properties of PP will allow it to penetrate new markets.

Since its invention, plastic strapping tape has quickly replaced steel tape in many areas of activity. In most cases, the strength of such a tape is more than sufficient, and it varies depending on the parameters and type of tape.

The advantages of plastic tape over steel have long become obvious to many:

• • no corrosion;
  • price;
  • weight;
  • plastic.

Indeed, it is difficult to argue with the above characteristics, because at least the first three raise absolutely no doubts, and the plasticity allows you to keep the edges of packaged goods intact, because the steel tape simply crushes them.

Polypropylene tape, or PP for short, is the most popular due to its good price-quality ratio. So, we can say with confidence that it can strap most loads, and the cost is confidently superior compared to other types of similar materials. Types of strapping can be as follows:

• • auto;
  • semi-automatic;
  • manual.

All of them require special equipment and partial or full human participation. So, the first one is used for tying boxes with various goods - the sizes of which are unified. Manual lifting is mostly used for cargo with constant differences in volume and weight characteristics. So, buying polypropylene tape in Moscow is absolutely no problem.

Loads are packed exclusively by hand using PET polyester tape, and it is found on the shelves of construction stores much less frequently than PP tape. But the weights it can withstand are comparable to metal tape, but the cost of the latter is correspondingly higher. In addition, it is necessary not just to compare the price of a coil of one or another type of product, but to look first of all at the footage, which is smaller for PET than for PP by definition. This tape is also called lavsan, so don’t be afraid of this word, but simply understand what it means and what stands behind it.

The main parameters that you should look at when choosing a strapping material are width and thickness, since tensile strength directly depends on them. Ribbon PP can withstand up to 450 kg, and if you buy PET tape, you can count on the ability to withstand up to 1000 kg. Despite this difference, you need to understand that by wrapping the load once again, the load arising from it will also be proportionally distributed to each harness. Such manipulations are not always justified, but if they are still possible, polypropylene tape turns out to be more profitable.

The results of a comparison of two types of plastic tapes indicate that preference should still be given to polypropylene material, but despite this, in some cases it is simply impossible to do without a Mylar competitor. Be that as it may, the Pakland company has in its assortment all types of tapes, which our specialists will select according to the characteristics of the product with which they will be used.