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Cosmetic packaging barrier
FROM: AUTUR: education-86 DATE: 2017/9/25 13:57:28 ：1153 TIME
The barrier property of cosmetic packaging
Review and the barrier property of the new - cosmetic packaging
Packaging needs to be both protective, functional and decorative requirements in one, the protective function of packaging is the most basic and most important function, and good barrier is one of the requirements for packaging protection function.
Packaging materials for cosmetics, except for themselves with good barrier glass, ceramic and metal materials, whether blown bottles or injection cans, regardless of the hose or film, are made of high polymer materials such as polyethylene ( PE ), polypropylene ( PP ), polyethylene terephthalate ( pet ), polyethylene - vinyl alcohol copolymer ( evoh ) or the physical or chemical modification of these materials, that is, we are often described as plastic. The microstructure of plastics shows that the plastic material is not " airtight ", as shown in the figure below, the surface of PE and PP material is observed under high power electron microscope, and the material memory in the hole is enough to make us realize that the plastic material itself has a certain permeability.
So do we need to consider the barrier of cosmetic packaging? The answer is yes. In fact, in the development of food packaging, the barrier and sealing of the packaging is attached importance, it has the effect of quality, preservation, flavor and prolong the shelf life of food. However, in the development of cosmetics packaging, it is often overlooked in the tightness of the packaging, but also ignore the packaging barrier, which is why in the actual cosmetics development will encounter the overall packaging to do a good cosmetic cream or emulsion products, after a period of time to open found that the cream texture thickening, or even can not be used; There are also some formulations containing volatile organic compounds, which slowly penetrate through packaging materials to lead to the deficiency of the corresponding active components. So the cosmetics packaging development needs to consider the barrier function of packaging, in order to ensure good use of skin sense, preserve the effect and extend the shelf life of the product. Only the correct understanding of the barrier definition and penetration mechanism of the material, understanding of the barrier properties of polymer materials, can in the cosmetics packaging development work according to the actual needs of the choice of suitable packaging materials, do the edge.
1. definition of material barrier
1. the barrier property of the material is the permeability of a specific permeable material from one side of the material to the other side ( generally by the high concentration side penetration through the material into the low concentration side ), common permeability including inorganic gas, water vapor and organic matter. According to the permeability of the different properties, the barrier is called permeability ( oxygen permeability, nitrogen permeability, carbon dioxide permeability, etc. ), moisture permeability and organic matter.
2. generally, we say that the barrier property of the material means that the material should have good gas barrier, water vapor barrier and organic barrier property, and that the barrier property of the material should be good for the specific permeability. The single material is difficult to meet the good barrier for all permeability, such as the material with good gas barrier properties in fact, the barrier of water vapor and organic matter may not be good, even if the gas barrier of some kind of material refers to the specific gas has good barrier, such as good oxygen resistance or nitrogen resistance; For example, the water resistance of common HDPE is better than that of pa, but the resistance of the gas is lower than pa. For example, evoh has a high gas barrier when the environment humidity is low, but with the increase of environmental humidity, the barrier of inorganic gas will obviously decline, the corresponding barrier water vapor performance becomes poor. Therefore, in the actual supplier of cosmetics packaging barrier requirements, the need to specify what the barrier requirements. Depending on the direction of penetration, there is a distinction between infiltration or seepage.
Ii. percolation mechanism
1. the high barrier property of the material to a specific permeability represents the low permeability of the material, such as low oxygen permeability, which represents high resistance oxygen, and low moisture permeability indicates high resistance water. Barrier can be said to be a barrier permeability, understanding of the infiltration of the packaging materials in the process, can help us understand the impact of barrier factors.
2. the whole infiltration process can be divided into four parts: adsorption, dissolution, diffusion and desorption, the gas, water vapor or organic matter enters the material surface from the high concentration area, and is desorbed from the other surface of the low concentration area through the diffusion in the material. Assuming that the high moisture content of the cosmetics in the low humidity environment, we use this model to simulate the process of water loss in the packaging container, as shown in figure 2, water vapor will contact the inner wall of the packaging container, dissolve into the packaging layer, in the material along the concentration gradient diffusion, the final desorption diffusion into the atmosphere, if the external temperature increases, it will accelerate the infiltration process. This can also be explained before the mention of even if the seal has been good cosmetics, or because of the water vapor leakage, resulting in the product thickening and thickening effect consumer use.
3. the small molecular permeability through the polymer is mainly through the amorphous region and the crystallization defect part, the micro crack, pinhole, defect will lead to the increase of permeability. From figure 1, we can see the obvious material defects under high magnification microscope.
Iii. the factors affecting the barrier properties of polymer materials
1. the permeability of the permeate to the packaging material depends on the type of the penetration ( molecular volume, shape and polarity ), the structure and properties of the polymer material and the interaction of the permeability with the polymer material ( polarity similarity ). The actual infiltration process is usually affected by these three factors. because of the variety of the permeability and the interaction between the materials is more complex, this paper only analyzes the influence of polymer structure and performance on the packaging barrier.
2. the factors affecting the barrier properties of packaging materials include the chain structure, phase structure, crystallinity, orientation and stacking state of the materials, and the different packaging technology will also affect the barrier properties of the final materials.
There is a literature in the field of polymer research that the barrier itself must have the following structural characteristics
1. some degree of polarity. For example, there are fluorine atoms in the molecular chain, hydroxyl and ester groups exist; As shown in table 1 below, the resistance to oxygen of polyvinyl alcohol with hydroxyl on the molecular chain side is significantly better than that of polyethylene. 1486611162693826. jpg
2. the polymer chain has high rigidity and inertia for the permeate;
3. due to the molecular symmetry, ordering, crystallization or orientation, the polymer chain has the ability to stack tightly; A polymer can have different degrees of crystallization. High crystallinity can bring better barrier property. The barrier differences between polyolefins at different crystallinity are shown in table 2 below. Generally, higher crystallinity has a lower permeability. 1486611217877746. jpg
The orientation of polymer molecular chain has great influence on its barrier properties, and the molecular chain orientation can reduce the permeability of 10 - 15 %. For crystalline polymers, the penetration of more than 50 % can be observed. Orientation has a special relationship with the blow molding process of the bottle. Therefore, it is more effective to improve the barrier properties of the bottle by controlling the orientation in the blowing process than the barrier coating on the outside of the bottle, such as PP, PS and pet, the resistance to oxygen is significantly improved after the orientation of PP, PS and pet, and the elongation of 500 % pet is nearly 50 % higher than the not barrier.
4. there is a bond force or attraction between the polymer chain and the chain;
5. high glass transition temperature
In general, the linear polymer with simple molecular structure will have the regular stacking state and high barrier capacity, but the main chain skeleton caused by the large scale of the pile is poor in regularity, and the barrier ability decreases.
" different materials processing molding technology has influence on the barrier properties of materials, choose the polymer with different characteristics, adopt the appropriate processing method can get the comprehensive performance excellent barrier materials. For example, LLDPE, LDPE barrier property is lower than HDPE, when extrusion single layer tube application, LLDPE, LDPE and HDPE physical blending can be made with a certain barrier and easy heat sealing hose packaging; For example, evoh is a crystalline polymer of ethylene / vinyl alcohol, which is a kind of crystalline polymer with good processability and high gas barrier property of polyvinyl alcohol. the presence of polar ethylene alcohol chain leads to good barrier property for non-polar solvent such as hydrocarbons. the presence of non-polar ethylene chain can improve the barrier properties of non-polar solvent, but the molecular structure of evoh resin has hydroxyl, evoh resin has hydrophilic and moisture absorption, the barrier properties of gas will be affected, so it is necessary to use multi-layer technology such as polyolefin such as strong partition resin
Application of barrier materials in cosmetics packaging
At present, the application of barrier packaging materials in the cosmetics packaging industry is in the use of growth period, domestic commonly used high barrier materials include aluminum foil, polyvinyl alcohol ( PVA ), ethylene - vinyl alcohol copolymer ( evoh ), nylon ( pa ), polyethylene terephthalate ( pet ), and so on. Aluminum foil, PVA, evoh belong to high barrier material, pa is similar to pet, belonging to medium barrier material.
For hose packaging cosmetics, if the product itself has high barrier requirements, usually choose the following three types of barrier plastic hoses.
1. aluminum - plastic composite hose, its typical structure is PE / PE + EAA / al / PE + EAA / PE. the Ctrl tube is made from aluminum foil and plastic film after extrusion. the blocking property mainly depends on the pinhole degree of aluminum foil, and the barrier property is enhanced when the thickness of aluminum foil is increased;
2. the plastic barrier composite hose, its typical structure is PE / PE / evoh / PE / PE, all made of plastic, its barrier layer is usually evoh or oxide coating pet, with the increase of evoh thickness, barrier enhancement;
3. five - layer structure plastic co - extrusion hose, the typical structure of PE / mah - PE / evoh / mah - PE / PE, from a variety of plastics together through the screw extrusion molding to make a sheet, also through the evoh to play a blocking role.
Cosmetics for film packaging
Common barrier films of common extrusion type barrier film, laminating class ( dry composite class, solventless composite class, hot melt adhesive composite type, extrusion composite class ) barrier film, evaporated type ( vacuum aluminum, aluminum oxide, coated oxide ) barrier film, respectively by co - extrusion method, laminating composite method, coating method and steam plating process, the structure is not detailed description, commonly used in the structure of pet / al / PE, pet / al / CPP, pet / vmp et / PE, pet / evoh / PE, and pet / al / pet / PE
For the enhancement of pet bottles
The barrier properties of the modified materials and new technology are also reported, but for the pet bottles as cosmetics, if not encounter the more sensitive formula can basically meet the existing barrier requirements.
Summary
Note that the barrier property of the above cosmetics packaging refers to the barrier of inorganic gas and water vapor. if there are some volatile small organic compounds in the formula, the actual situation is needed, because the factors affecting the penetration are not only the packaging material itself, but also with the structure, size and the interaction between small molecular organic substances and polymer materials, we need to know the cosmetics formula of these volatile active ingredients, and then choose several different barrier packaging for barrier test, finally select the appropriate packaging container.
Review and the barrier property of the new - cosmetic packaging
Packaging needs to be both protective, functional and decorative requirements in one, the protective function of packaging is the most basic and most important function, and good barrier is one of the requirements for packaging protection function.
Packaging materials for cosmetics, except for themselves with good barrier glass, ceramic and metal materials, whether blown bottles or injection cans, regardless of the hose or film, are made of high polymer materials such as polyethylene ( PE ), polypropylene ( PP ), polyethylene terephthalate ( pet ), polyethylene - vinyl alcohol copolymer ( evoh ) or the physical or chemical modification of these materials, that is, we are often described as plastic. The microstructure of plastics shows that the plastic material is not " airtight ", as shown in the figure below, the surface of PE and PP material is observed under high power electron microscope, and the material memory in the hole is enough to make us realize that the plastic material itself has a certain permeability.
So do we need to consider the barrier of cosmetic packaging? The answer is yes. In fact, in the development of food packaging, the barrier and sealing of the packaging is attached importance, it has the effect of quality, preservation, flavor and prolong the shelf life of food. However, in the development of cosmetics packaging, it is often overlooked in the tightness of the packaging, but also ignore the packaging barrier, which is why in the actual cosmetics development will encounter the overall packaging to do a good cosmetic cream or emulsion products, after a period of time to open found that the cream texture thickening, or even can not be used; There are also some formulations containing volatile organic compounds, which slowly penetrate through packaging materials to lead to the deficiency of the corresponding active components. So the cosmetics packaging development needs to consider the barrier function of packaging, in order to ensure good use of skin sense, preserve the effect and extend the shelf life of the product. Only the correct understanding of the barrier definition and penetration mechanism of the material, understanding of the barrier properties of polymer materials, can in the cosmetics packaging development work according to the actual needs of the choice of suitable packaging materials, do the edge.
1. definition of material barrier
1. the barrier property of the material is the permeability of a specific permeable material from one side of the material to the other side ( generally by the high concentration side penetration through the material into the low concentration side ), common permeability including inorganic gas, water vapor and organic matter. According to the permeability of the different properties, the barrier is called permeability ( oxygen permeability, nitrogen permeability, carbon dioxide permeability, etc. ), moisture permeability and organic matter.
2. generally, we say that the barrier property of the material means that the material should have good gas barrier, water vapor barrier and organic barrier property, and that the barrier property of the material should be good for the specific permeability. The single material is difficult to meet the good barrier for all permeability, such as the material with good gas barrier properties in fact, the barrier of water vapor and organic matter may not be good, even if the gas barrier of some kind of material refers to the specific gas has good barrier, such as good oxygen resistance or nitrogen resistance; For example, the water resistance of common HDPE is better than that of pa, but the resistance of the gas is lower than pa. For example, evoh has a high gas barrier when the environment humidity is low, but with the increase of environmental humidity, the barrier of inorganic gas will obviously decline, the corresponding barrier water vapor performance becomes poor. Therefore, in the actual supplier of cosmetics packaging barrier requirements, the need to specify what the barrier requirements. Depending on the direction of penetration, there is a distinction between infiltration or seepage.
Ii. percolation mechanism
1. the high barrier property of the material to a specific permeability represents the low permeability of the material, such as low oxygen permeability, which represents high resistance oxygen, and low moisture permeability indicates high resistance water. Barrier can be said to be a barrier permeability, understanding of the infiltration of the packaging materials in the process, can help us understand the impact of barrier factors.
2. the whole infiltration process can be divided into four parts: adsorption, dissolution, diffusion and desorption, the gas, water vapor or organic matter enters the material surface from the high concentration area, and is desorbed from the other surface of the low concentration area through the diffusion in the material. Assuming that the high moisture content of the cosmetics in the low humidity environment, we use this model to simulate the process of water loss in the packaging container, as shown in figure 2, water vapor will contact the inner wall of the packaging container, dissolve into the packaging layer, in the material along the concentration gradient diffusion, the final desorption diffusion into the atmosphere, if the external temperature increases, it will accelerate the infiltration process. This can also be explained before the mention of even if the seal has been good cosmetics, or because of the water vapor leakage, resulting in the product thickening and thickening effect consumer use.
3. the small molecular permeability through the polymer is mainly through the amorphous region and the crystallization defect part, the micro crack, pinhole, defect will lead to the increase of permeability. From figure 1, we can see the obvious material defects under high magnification microscope.
Iii. the factors affecting the barrier properties of polymer materials
1. the permeability of the permeate to the packaging material depends on the type of the penetration ( molecular volume, shape and polarity ), the structure and properties of the polymer material and the interaction of the permeability with the polymer material ( polarity similarity ). The actual infiltration process is usually affected by these three factors. because of the variety of the permeability and the interaction between the materials is more complex, this paper only analyzes the influence of polymer structure and performance on the packaging barrier.
2. the factors affecting the barrier properties of packaging materials include the chain structure, phase structure, crystallinity, orientation and stacking state of the materials, and the different packaging technology will also affect the barrier properties of the final materials.
There is a literature in the field of polymer research that the barrier itself must have the following structural characteristics
1. some degree of polarity. For example, there are fluorine atoms in the molecular chain, hydroxyl and ester groups exist; As shown in table 1 below, the resistance to oxygen of polyvinyl alcohol with hydroxyl on the molecular chain side is significantly better than that of polyethylene. 1486611162693826. jpg
2. the polymer chain has high rigidity and inertia for the permeate;
3. due to the molecular symmetry, ordering, crystallization or orientation, the polymer chain has the ability to stack tightly; A polymer can have different degrees of crystallization. High crystallinity can bring better barrier property. The barrier differences between polyolefins at different crystallinity are shown in table 2 below. Generally, higher crystallinity has a lower permeability. 1486611217877746. jpg
The orientation of polymer molecular chain has great influence on its barrier properties, and the molecular chain orientation can reduce the permeability of 10 - 15 %. For crystalline polymers, the penetration of more than 50 % can be observed. Orientation has a special relationship with the blow molding process of the bottle. Therefore, it is more effective to improve the barrier properties of the bottle by controlling the orientation in the blowing process than the barrier coating on the outside of the bottle, such as PP, PS and pet, the resistance to oxygen is significantly improved after the orientation of PP, PS and pet, and the elongation of 500 % pet is nearly 50 % higher than the not barrier.
4. there is a bond force or attraction between the polymer chain and the chain;
5. high glass transition temperature
In general, the linear polymer with simple molecular structure will have the regular stacking state and high barrier capacity, but the main chain skeleton caused by the large scale of the pile is poor in regularity, and the barrier ability decreases.
" different materials processing molding technology has influence on the barrier properties of materials, choose the polymer with different characteristics, adopt the appropriate processing method can get the comprehensive performance excellent barrier materials. For example, LLDPE, LDPE barrier property is lower than HDPE, when extrusion single layer tube application, LLDPE, LDPE and HDPE physical blending can be made with a certain barrier and easy heat sealing hose packaging; For example, evoh is a crystalline polymer of ethylene / vinyl alcohol, which is a kind of crystalline polymer with good processability and high gas barrier property of polyvinyl alcohol. the presence of polar ethylene alcohol chain leads to good barrier property for non-polar solvent such as hydrocarbons. the presence of non-polar ethylene chain can improve the barrier properties of non-polar solvent, but the molecular structure of evoh resin has hydroxyl, evoh resin has hydrophilic and moisture absorption, the barrier properties of gas will be affected, so it is necessary to use multi-layer technology such as polyolefin such as strong partition resin
Application of barrier materials in cosmetics packaging
At present, the application of barrier packaging materials in the cosmetics packaging industry is in the use of growth period, domestic commonly used high barrier materials include aluminum foil, polyvinyl alcohol ( PVA ), ethylene - vinyl alcohol copolymer ( evoh ), nylon ( pa ), polyethylene terephthalate ( pet ), and so on. Aluminum foil, PVA, evoh belong to high barrier material, pa is similar to pet, belonging to medium barrier material.
For hose packaging cosmetics, if the product itself has high barrier requirements, usually choose the following three types of barrier plastic hoses.
1. aluminum - plastic composite hose, its typical structure is PE / PE + EAA / al / PE + EAA / PE. the Ctrl tube is made from aluminum foil and plastic film after extrusion. the blocking property mainly depends on the pinhole degree of aluminum foil, and the barrier property is enhanced when the thickness of aluminum foil is increased;
2. the plastic barrier composite hose, its typical structure is PE / PE / evoh / PE / PE, all made of plastic, its barrier layer is usually evoh or oxide coating pet, with the increase of evoh thickness, barrier enhancement;
3. five - layer structure plastic co - extrusion hose, the typical structure of PE / mah - PE / evoh / mah - PE / PE, from a variety of plastics together through the screw extrusion molding to make a sheet, also through the evoh to play a blocking role.
Cosmetics for film packaging
Common barrier films of common extrusion type barrier film, laminating class ( dry composite class, solventless composite class, hot melt adhesive composite type, extrusion composite class ) barrier film, evaporated type ( vacuum aluminum, aluminum oxide, coated oxide ) barrier film, respectively by co - extrusion method, laminating composite method, coating method and steam plating process, the structure is not detailed description, commonly used in the structure of pet / al / PE, pet / al / CPP, pet / vmp et / PE, pet / evoh / PE, and pet / al / pet / PE
For the enhancement of pet bottles
The barrier properties of the modified materials and new technology are also reported, but for the pet bottles as cosmetics, if not encounter the more sensitive formula can basically meet the existing barrier requirements.
Summary
Note that the barrier property of the above cosmetics packaging refers to the barrier of inorganic gas and water vapor. if there are some volatile small organic compounds in the formula, the actual situation is needed, because the factors affecting the penetration are not only the packaging material itself, but also with the structure, size and the interaction between small molecular organic substances and polymer materials, we need to know the cosmetics formula of these volatile active ingredients, and then choose several different barrier packaging for barrier test, finally select the appropriate packaging container.
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