Oxygen barrier performance test method and instrument for PVDC coated film material

Abstract:Coating PVDC layer on the surface of the material is a common method to improve the barrier of materials, this paper further studies the influence of different PVDC coatings on the barrier properties of materials by testing the oxygen permeability of film materials with different coating amounts, and introduces the test principle, equipment parameters and scope of application, test process, etc.
, to provide a reasonable evaluation method
for the change of barrier properties after material modification or improvement process.

Keywords: PVDC coating film, K coating, coating amount, barrier, oxygen permeability, differential pressure gas permeability tester 1, significance polyvinylidene chloride (PVDC) is a polymer material with high symmetry, high crystallinity, high barrier and other characteristics, but the molding processability is poor, generally need to be copolymerized with other monomers, using injection molding, extrusion, composite, coating and blow molding and other methods of processing, Among them, K films made of one or more layers of PVDC coated on various film substrates are the most common
.

Commonly used coating substrates include PP, PET, PA, PE, etc.
, due to the presence of PVDC greatly improve the overall barrier performance of the film, enhance the barrier of the film to gases and fragrance retention, oil resistance, etc.
, so it is widely used in packaging mooncakes, biscuits, tea, pastries, chocolate, dairy products, meat products, aquatic products, condiments and other foods
.

The barrier properties of K film mainly depend on the PVDC layer, so the amount of coating of the PVDC layer is an important factor
affecting the barrier properties of K film.

2.
The test samples in this test take the K film material with PVDC coating amounts of 2 g/m2 and 4 g/m2 as the test samples, and the oxygen permeability
of the two samples is tested respectively.

3, the test according to the film material oxygen permeability test principle includes differential pressure method, isobaric method two, this article using the principle of differential pressure method for testing, based on the standard is GB/T 1038-2000 "plastic film and flake gas permeability test method pressure difference method"
.

4.
The test equipment is tested by the VAC-V2 differential pressure gas permeometer independently developed and produced by Jinan Languang Electromechanical Technology Co.

, Ltd.

4.
1 Test principle The principle of differential pressure method refers to the principle of maintaining a certain pressure difference on both sides of the specimen, and the gas permeability performance
of the specimen is obtained by testing the pressure change caused by gas permeation.

The clamped specimen divides the test chamber of the equipment into two chambers, the upper chamber is filled with test gas, the lower chamber is formed by vacuuming to form a low-pressure environment, the gas in the upper cavity will penetrate into the lower cavity through the sample under the action of pressure difference, monitor the pressure change in the low-pressure chamber through the pressure sensor, when the permeation reaches equilibrium, calculate the sample gas transmission amount and other parameters
according to the change of pressure in the low-pressure chamber with the permeation time.

This method can test the permeability of a variety of gases
.

4.
2 Scope of application (1) This equipment is professionally used for the test
of gas transmittance, permeability coefficient, solubility coefficient and diffusion coefficient of a variety of film and sheet specimens at various temperatures.

Film category includes a variety of plastic film, paper-plastic composite film, co-extrusion film, aluminum coating film, aluminum foil, aluminum foil composite film and other film-like materials; Sheets include a variety of engineering plastics, rubber, building materials and other sheet materials, such as PP sheets, PVC sheets, PVDC sheets
.

(2) This equipment can also be extended to aerospace materials, paper and cardboard, paint film, glass fiber cloth, glass fiber paper, cosmetic hose sheet, various rubber sheets and other materials breathability test
.

(3) This equipment is suitable for transmittance testing of a variety of gases, such as oxygen, carbon dioxide, nitrogen, helium, air, etc
.

(4) This equipment can meet a number of national and international standards, such as ISO 15105-1, ISO 2556, GB/T 1038, ASTM D1434, JIS K7126-1, YBB00082003, etc
.

4.
3 The equipment parameter test range is 0.
05 ~ 50,000 cm3/(m2·24h·0.
1 MPa), and the vacuum resolution can reach 0.
1 Pa; The temperature control range is 5 °C ~ 95 °C, and the temperature control accuracy is ±0.
1 °C; Humidity control range of 0%RH, 2%RH ~ 98.
5%RH, 100%RH, humidity control accuracy of ±1%RH, can meet the customer's testing needs under different test conditions; Three completely independent test chambers that can test three identical or different specimens at the same time; Data fitting at any temperature can be performed to easily obtain test results under very special test conditions; After restructuring, the equipment can also support the test of toxic gases, flammable and explosive gases; Provide standard membranes for rapid calibration to ensure the accuracy and versatility of inspection data; Support LystemTM laboratory data sharing system for unified management of test results and test reports
.

5.
Test process 5.
1 K film sample with a coating amount of 2 g/m2 (1) Cut 3 samples with a diameter of 97 mm from the sample surface
.

(2) The sample is coated with a layer of vacuum grease around the periphery of the three test chambers, and the filter paper with a diameter of 65 mm is placed in the test area, the specimen is pasted on the test chamber, the specimen is gently pressed to remove the bubbles, and the specimen is
clamped with the clamping structure.

(3) Test set test temperature, test humidity, specimen thickness and other parameter information, open the vacuum pump, water bath temperature control device, click start test option, test start
.

The equipment automatically performs the test according to the set parameters and displays the test results after the test is
completed.

5.
2 K membrane samples with a coating amount of 4 g/m2 are tested
according to the operation steps in 5.
1.

6.
Test resultsThe test values of the K film specimen with a coating amount of 2g/m2 tested in this test were 7.
85 cm3/(m2·24h·0.
1MPa), 7.
69 cm3/(m2·24h·0.
1MPa), 7.
99 cm3/(m2·24h·0.
1MPa), with an average value of 7.
84 cm3/(m2·24h·0.
1MPa); The test values of K-film specimens with a coating volume of 4 g/m2 were 4.
79 cm3/(m2·24h·0.
1MPa), 4.
83 cm3/(m2·24h·0.
1MPa), and 4.
67 cm3/(m2·24h·0.
1MPa), with a mean value of 4.
76 cm3/(m2·24h·0.
1MPa).


7.
Conclusion From the test results, the deviation between the test values of each sample 3 samples is small, the test accuracy is high, and the oxygen transmission of the coating amount of 4 g/m2 K film is significantly lower than that of the K film with a coating amount of 2 g/m2, indicating that the former has a high oxygen barrier, and the factors affecting the barrier of the K film of the same substrate include the coating method and coating process in addition to the coating amount of the PVDC layer, because the two samples tested in this article are produced by the same manufacturer.
The influence of the coating method and coating process is small, and the difference in oxygen resistance is mainly related to the amount of coating; From the perspective of the test process, the operation is simple and the equipment is highly
intelligent.

In addition to testing oxygen transmission, the equipment can also be used for nitrogen, air, helium, carbon dioxide, sulfur hexafluoride and other gases permeation behavior test, and the test efficiency is high, is a cost-effective testing equipment
.

Labthink Languang is a professional packaging testing equipment research and development and testing services technology enterprises, to understand the testing equipment and service information, you can log on to the Jinan Languang company website to view specific information or call for consultation
.

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