JPH06273309A - Gas permeability measuring equipment for resin film - Google Patents

Abstract

PURPOSE:To allow gas permeation rate to be highly sensitive measured by sealing a measuring equipment hermetically while bringing a barrier resin film, on one side thereof, into contact with a volatile liquid and taking out a gas component permeated through the barrier resin film from the other side thereof using an inert gas being fed by a predetermined quantity. CONSTITUTION:An inert gas is fed from an inlet gas line 10 through an open ring 7 into a permeated gas collecting collection space 17 while being regulated in flow rate by a valve 12 such that a concentration optimal for analysis is attained. The inert gas contains vapor of a volatile liquid (e.g. gasoline) 3 evaporated after permeating through a gas barrier resin film 4 in the space 17 and carried through an outlet gas line 11 to a gas chromatograph where the concentration of gas is determined. Gas permeation rate can be calculated on the basis of the data of the gas concentration thus determined, the flow rate of inert gas, and the area of resin film. Lower limit in the determineation of permeation rate is 3E-6(g/(day.cm<2>)). The ratio between liquid phase and gas phase on the contact face of the film 4 and the liquid 3 in a vessel 2 can be set freely by adjusting the angle using an angle setting handle 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas permeability measuring device for a volatile liquid polymer resin film. For more information,
Used in plastic gasoline tanks and drums,
The present invention relates to a gas permeability measuring device for gasoline or the like from a polymer resin container.

[0002]

2. Description of the Related Art In recent years, with the progress of large-scale blow molding technology, automobile gasoline tanks, drums, etc. are made of resin, especially polyolefin (especially HD
Containers made of PE: high density polyethylene) are beginning to be used. Resin containers such as gasoline tanks have many advantages over metal ones such as freedom of shape, rust prevention, impact resistance, and light weight. The problem is that the gas barrier property is low, and improvement of the gas barrier property is raised from the viewpoint of handling hazardous materials and environmental protection (eg, new SHED evaporation regulation in California, USA).

As a countermeasure against this, the inside of the resin tank is currently SO
Methods such as chemical treatment with ₃ or F ₂ and a method of forming a multi-layer structure with a gas barrier resin sandwiched therebetween are being studied. Conventionally, as a gas barrier property evaluation method for this gasoline tank or the like, a small amount of blow-molded resin bottle or a predetermined amount of the volatile liquid of interest is put in the main body of the gasoline tank, and it is left in a predetermined constant temperature environment for a predetermined period of time, and at fixed time intervals. By measuring the weight, a method of obtaining the gas permeation rate from the weight loss rate has been taken.

Although this method has an advantage that the gas permeability from the whole of an actual tank or the like can be known, since it is a blow-molded product, unevenness in the thickness of the gas barrier resin occurs particularly in a multilayer molded product, which causes the film thickness of the gas barrier property. There is a drawback that it is difficult to grasp the dependency. Also, in terms of measurement sensitivity (since the accuracy of a commercially available balance is usually only 5 to 6 digits below the maximum weight), the conventional method has a heavy container weight, and therefore the difference between the total weight and the weight change amount is large. However, even if a large and accurate balance is used, the measurement sensitivity is insufficient in view of the amount of gas permeation required in recent years, and it has been necessary to watch at least several months.

Further, since the result is only the change in weight, it is not known what kind of change will occur when passing through the gas barrier material when the volatile liquid is a mixed liquid of multiple components. When the volatile liquid comes into contact with the resin film, it is not known how the gas permeation and the liquid phase side of the volatile liquid affect the gas permeation. There were many problems in conducting research and development.

[0006]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to solve the problem of the method for measuring the gas permeability of volatile liquids such as gasoline, and as a result, not the evaluation of the permeation rate due to the weight reduction, For example, one side of a barrier resin film with a constant film thickness created by sheet molding is sealed in contact with gasoline and the like, and a small amount of a small amount of gas components such as gasoline that has permeated from the other side. By continuously taking out the flowed inert gas to suppress the partial pressure rise of the permeation component and maintaining a stable gas permeation state, this flow gas is sampled with a gas sampler at regular time intervals to achieve high sensitivity. The method of measuring by gas chromatography was examined.

Further, by making the volatile liquid permeation cell variable up and down 360 ° (the variable angle is not limited to 360 °, but is optional according to the purpose), the contact area between the volatile liquid and the resin film can be set at an arbitrary ratio. I made it possible to change. As a result, it was possible to fabricate a device that could measure the gas permeation rate over time with high sensitivity in a state closer to a natural gasoline tank, and could also know the composition of the permeated gas.

By using this apparatus, it was found that all the problems in the conventional method can be solved, and the present invention was completed.

[0009]

Means for Solving the Problems The gist of the present invention is a container for containing a volatile liquid, a means for fixing a resin film on the upper part of the container, and an inclination of the container to adjust the contact area of the volatile liquid with respect to the resin film. And a permeated gas recovery space that is provided so as to cover the upper part of the resin film and that has an inert gas inlet and outlet, and a gas permeation measuring device for a resin film.

The present invention will be described in detail below. Figure 1
FIG. 1 is a schematic explanatory view showing an example of a gas permeability measuring device of the present invention. In the figure, 1 is a gas permeability measuring device, 2 is a container, 3
Is a volatile liquid, 4 is a resin film, 5 is a fixed ring, 6 is an O-ring, 7 is an open ring, 8 is a lid, 9 is a fixed frame, 10 is an inlet side gas line, 11 is an outlet side gas line, 12 Is a valve, 13 is a support plate, 14 is a support shaft, 15 is an angle setting handle, 16 is a thermostat, and 17 is a permeated gas recovery space.

The gas permeability measuring apparatus 1 of the present invention comprises a container 2 for containing a volatile liquid 3 and a permeated gas recovery space 17 provided on the upper part of the container 2. A description will be given according to the process of measuring. The resin film 4 to be measured is brought into close contact with the metal fixing ring 5. In this case, since the resin film 4 swells and is deformed by the volatile liquid 3 such as gasoline during the measurement, preventing the liquid leakage by the O-ring is not preferable as a method, and the metal fixing ring 5 is heated and the resin film is prevented. It is preferable to use the method of melt pressure bonding to No. 4.

Next, on the other surface of the resin film 4, there is formed an open ring 7 having a fixed area of holes (holes for introducing and discharging an inert gas for an analyzer such as gas chromatography). As a spacer, it is in close contact with the fixing ring 5 and is sealed with a lid 8 made of a material that does not cause adsorption. Separately, prepare a container 2 containing a predetermined amount of the volatile liquid 3 (gasoline etc.) in the space for storing the volatile liquid 3, and install an O-ring 6 between the fixing ring 5 and the container 2. After being placed so as to fit in the grooves provided in each, the whole apparatus is sealed with the fixed frame 9 and a leak test of the permeated gas recovery space 17 that has permeated the volatile liquid 3 and the resin is conducted.

If the leak test is OK, the gas permeability measuring device 1 is installed on the support plate 13 in the constant temperature bath 16 via the support shaft 14. The support plate 13 is fixed to the bottom surface of the constant temperature bath 16 so that the gas permeability measuring device 1 can be set at an arbitrary angle by the support shaft 14. The angle may be adjusted by any method such as the angle setting handle 15. By adopting such a structure that the angle of the gas permeability measuring device 1 can be set to an arbitrary angle, the liquid phase and the gas phase of the volatile liquid 3 on the contact surface between the resin film 4 and the volatile liquid 3 can be changed. The proportion of the phase part can be set arbitrarily.

Therefore, when it is desired to change the ratio of the liquid phase portion and the gas phase portion depending on the product to measure the gas permeability, the object can be achieved by merely adjusting the angle with the angle setting handle 15. In the installed gas permeability measuring device 1, an inert gas whose flow rate was adjusted by a valve 12 such as a constant flow valve so as to have an optimum concentration for analysis was introduced from the introduction side gas line 10 into a hole of an open ring. It is then supplied to the permeated gas recovery space 17.

The supplied inert gas contains the vapor (gas) of the volatile liquid 3 vaporized after passing through the resin film 4 in the permeated gas recovery space 17, and is normally kept at the outlet side gas line 11
Is carried to a gas chromatograph or the like (not shown) for analysis. Although the above description has been made by taking a series of analyzes as an example, when performing long-term temporal analysis, it is more efficient to install several gas permeability measuring devices 1 in the constant temperature bath 16 and perform sequential analysis. .

The lower limit of quantification of the transmission rate by the conventional method is
It was 3E-5 (g / (day · cm ² )). The lower limit of quantification of this analysis method was 3E-6 (g / (day · cm ² )), and it was confirmed that the concentration method further improves to 5E-8 (g / (day · cm ² )). . As for the analyzer, if the composition of the permeated gas is not needed, TOC (total carbon content analyzer)
But good.

The volatile liquid is a refined petroleum product such as gasoline or its derivative, and the resin film is based on polyolefin such as polyethylene, and is a target volatile liquid such as nylon and EVOH (ethylene-vinyl acetate copolymer). On the other hand, a multi-layer molded product in which a resin having gas barrier properties is sandwiched, and
A polyolefin resin or the like whose surface is chemically treated with SO ₃ , F ₂ or the like to have a gas barrier property is suitable for measurement. Next, a method for calculating the gas permeation rate using the device of the present invention will be described. The calculation is expressed by the following formula.

Gas permeation rate (g / (day · cm ² )) = gas concentration (g / ml) × inert gas flow rate (ml / min) × 60 × 24 (mi
n / day) / resin film area (cm ² ) where the gas concentration is a value obtained by gas chromatography analysis, the inert gas flow rate is a value obtained by a flow meter, and the resin film area is an open hole. Use the internal area of the ring 7.

[0019]

EXAMPLES The following is an example of analysis and examination of a barrier resin for a gasoline tank using the apparatus of the present invention, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 HDPE (600 μm) / EVOH was used as a resin film sample by using the gas permeability measuring device having the structure shown in FIG.
The gas permeability of the (300 μm) two-layer resin plate was measured.
The side in contact with the volatile liquid was HDPE.

The conditions of the gas permeability measuring device are as follows.

[0021]

[Table 1] Resin membrane area: 23.8 cm ² Gasoline capacity: 20 ml Temperature-controlled bath temperature: 40 ± 1 ° C Sample introduction method: Nitrogen 1.2 ± 0.5 ml / min to continuously permeate gas components to the measuring tube of the gas chromatograph Introduction The gas chromatography analyzer used is as follows. Model: Shimadzu GC-14A Column: Fused silica capital column Carrier gas: Helium 5 ml / min Detector: FID

The gas permeability measuring device is tilted at about 90 degrees with an angle setting handle, and approximately 1/2 of the resin film surface is in the liquid phase and 1/2 is in the liquid phase.
Was in contact with the gas phase. The measurement result of 5 times is 7.8.
2, 8.39, 8.37, 8.14, 7.82 (E-
5) (g / (day · cm ² )) with a coefficient of variation of 3.
It was very good at 46%. The coefficient of variation at the gas permeation rate of this level in the case of the conventional measuring method using a bottle is usually 10% or more, so it can be said that the measurement result is stable.

[0023]

In the analyzer of the present invention, the ratio of the volatile liquid in contact with the gas phase and the liquid phase can be set arbitrarily, so that the measurement can be performed according to the purpose. Moreover, since the measurement accuracy is extremely good, stable measurement results can be obtained. Furthermore, since the measurement sensitivity has been greatly improved, the measurement time with a resin having a low gas permeation amount has been shortened, and it has become possible to compare the gas barrier performance of barrier resins that were difficult to compare in terms of conventional measurement sensitivity. .

[Brief description of drawings]

FIG. 1 is a schematic view of the device of the present invention.

[Explanation of symbols]

 1 Gas Permeability Measuring Device 2 Container 3 Volatile Liquid 4 Resin Membrane 5 Fixing Ring 6 O Ring 7 Opening Ring 8 Lid 9 Fixing Frame 10 Introducing Gas Line 11 Outflowing Gas Line 12 Valve 13 Support Plate 14 Spindle 15 Angle Setting handle 16 Constant temperature chamber 17 Permeate gas recovery space

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Nobuyuki Shimizu 3-10-10 Shiododori, Kurashiki-shi, Okayama Mitsubishi Kasei Co., Ltd. Mizushima Plant

Claims (1)

[Claims] 1. A container for accommodating a volatile liquid, a means for fixing a resin film on the upper part of the container, a means for inclining the container to adjust the contact area of the volatile liquid with the resin film, and covering the upper part of the resin film. 1. A gas permeability measuring device for a resin membrane, comprising: a permeated gas recovery space provided with an inert gas introduction part and an outflow part.