Gas barrier performance testing and method analysis of soft plastic packaging materials

As we all know, in food, medicine, precision electronic components and other industries, the gas barrier performance of product packaging materials is a very important indicator, it can directly affect the preservation period of products, preservation environment, sales environment. the impact of
gases on food and medicine is early caused widespread concern in the soft packaging industry, oxygen penetration may lead to food quality, drug failure, etc. , now for food and pharmaceutical packaging, industry standards have been on the packaging film breathability and testing has a preliminary description.
here, we introduce you to the breathability of the film, detailing the effects of gas on the contents and the gas barrier testing methods that are now widely used.
this paper only introduces the testing of commonly used gases and does not involve organic gases.
1. The permeability of the packaging material is broadly transmitted through the material or material between the material and the content.
from a thermodynamic point of view, the penetration of small molecular substances into packaging materials is a single-molecule diffusion process, the speed of the whole process is determined by the solubility parameters and diffusion coefficients.
Without discussing packaging leakage, the film's barrier to the gas is the gas's penetration of the film: the gas molecule enters the surface of the material from a high concentration zone, through diffusion to the material, and is de-absorbed from another surface in the low concentration zone.
1.1 diffusion phenomenon diffusion phenomenon is due to uneven distribution of part density caused by mass transmission, the formation of mass flow.
, the diffusion phenomenon in the gas is directly related to the thermal motion of the gas molecule.
1.2 the effect of gas on contents is a very important indicator of the barrier properties of product packaging materials in industries such as food, medicine and precision electronic components.
such as fruit preservation, oxygen resistance and moisture resistance of packaging film (i.e. film barrier to oxygen and water vapor) are the factors that make fruit fresh.
such as wet pain cream, is the special need for oxygen-retardant packaging of drugs, the choice of blocking moisture good PVDC membrane packaging, odor will not be lost, will not affect the efficacy.
Oxygen in the air has a damaging effect on the nutritional content of food: oxygen oxidizes the fat in food, even at low temperatures;
For fruits and vegetables preservation, because fresh fruits and vegetables in the storage and circulation process in order to maintain its normal metabolic effect is still breathing, absorb a certain amount of oxygen and release a certain amount of CO2 and water, and consume a part of nutrition, low oxygen permeability of the film can reduce the release of water and consumption of nutrients, extend the shelf life of fruits.
In carbonated beverage packaging, due to PET has good transparency and strength, as well as the impermeability of CO2 and other advantages, PET plastic containers have accounted for 40% of the entire carbonated soft drink packaging, replacing a part of glass bottles and metal cans.
for pharmaceutical packaging, packaging materials can play an important role in the quality, validity, packaging form, sales, cost and so on.
General drug production, whether tablets, granules, injections, liquids, dispersants, or ointments, etc., are in a small number of varieties, and from the factory to reach the hands of patients to go through a more complex way.
pharmaceutical packaging materials should have stability, barrier performance, structural properties and good processing.
In the air to the drug shadow a large number of oxygen, oxygen can make many drugs, such as vitamin C, A, D and epinephrine, phenol and other oxidative degeneration, so that their main component content decreased, the efficacy of the reduced or ineffective.
that although many drugs have protective film, the resistance of drug packaging is still critical.
plastics currently used in packaging are still used in the world's six general plastics: PE, PP, PS, PVC, PA, PC, domestic pharmaceutical packaging in which PE, PVC, PP, and polyester.
Pharmaceutical packaging materials in addition to meeting the general performance of packaging materials, but also to meet the safety and applicability of special requirements, such as medicinal bubble packaging materials including medicinal aluminum foil, plastic hard pieces, thermal coatings and other materials, including medicinal aluminum foil to hard industrial pure aluminum as the base material, with non-toxic, corrosion-resistant, non-penetration, heat resistance, moisture resistance, light resistance, high temperature sterilization and other advantages.
Because the drug is very sensitive to moisture, wet, light transmission, so the foam material required to use on water, light, steam, etc. has a high barrier, multi-choice PVC, PVDC, or composite PVC/PE, PVC/PE, PVC/PE, PVDC/OPP/PE and so on.
2. Breathability test method from the test principle, breathability test method has two types of pressure difference method and through the power analysis sensor method, the pressure differential method is widely used to test film breathability.
2.1 pressure differential method of the determination principle of the film test chamber to be tested into two separate spaces, to one side (high-pressure chamber) filled with test gas, on both sides of the sample to form a certain pressure difference, high-pressure chamber gas through the film penetration into the low pressure chamber, by measuring the pressure or volume changes in the low-pressure chamber can be obtained gas permeability.
GB / T1038-2000 is the use of pressure differential method.
the existing pressure differential film breathability test standards are ASTMDl434-1998, ISO15105-1, ISO2556:2001 and so on.
pressure differential gas meter test range is wide, simple to use, can carry out a variety of gas testing, low test cost, equipment price is generally lower than the power analysis sensor method.
founded in 1989, Labthink has been deeply interested in the field of packaging physical performance testing for 30 years, in improving the level of detection in the industry, to promote the standardization of testing, standardization has done a lot of useful exploration.
Labthink for the quan ball market to introduce a new innovative work - C130H gas penetration test system, a pressure differential test principle based on the laboratory precision testing equipment, to help food, pharmaceutical, packaging and other scientific research and testing fields to achieve film, sheet gas pass rate, solubility coefficient, diffusion coefficient, penetration coefficient testing, and effectively promote its quality control, new product research and development process.
C130H is designed based on GB, ISO, ASTM and other national and international standards, and truly meets the requirements of the system for the pressure differential test standards.
the use of instrument and software integration, automation design, unattended operation is more reliable, suitable for different levels of operators to quickly grasp, application, accurate access to the penetration performance of material data.
2.2 Test principle of the power analysis sensor method The principle of the power analysis oxygen pass rate tester is to separate the test chamber into two separate airflow systems using the film to be tested, with the flowing gas on one side (but pure oxygen or oxygen-containing mixture gas, which sets the relative humidity of the gas) and the flowing nitrogen on the other.
The pressure difference between the two sides of the sample is equal but the oxygen pressure is different, under the effect of the concentration difference, the oxygen carried by the film is transported under the nitrogen flow to the power analysis sensor, so as to calculate the oxygen pass rate of the material.
power analysis equipment, low-end accuracy is high, because the pressure on both sides of the sample is the same, is conducive to reducing the leakage that may occur during the test, but this kind of instrument is expensive, and oxygen sensor is consumption-oriented, the test cost is higher.
such instruments have high accuracy for test samples with low oxygen pass, but due to the limitation of sensor service life, it is not suitable to often detect samples with high oxygen pass.
addition, the equipment has certain selectivity to the test gas.
Labthink Languang independently developed and produced the C230H oxygen pass rate test system, based on the Coulomb oxygen analysis sensor and iso-pressure test principle, with reference to asTM D3985 standard design and manufacture, for high, medium gas barrier materials to provide high-precision and high-efficiency oxygen pass-through rate testing.
suitable for food, pharmaceuticals, medical devices, daily chemistry, photovoltaic electronics and other fields of film, sheet, packaging and related materials oxygen through performance testing.
3.Conclusion The penetration of gas into packaging materials may cause contents to go bad and fail, which has a great impact on the shelf life of the product.
the existing pressure differential method and the power analysis sensor method in the world to detect gas passability, China's soft packaging testing industry in the field of breathability testing has developed rapidly.