JPH07174726A - Method for measuring moisture inside packaging material - Google Patents

Abstract

PURPOSE:To make it possible to efficiently measure the moisture inside a packaging material without opening or breaking down the packaging material, by measuring a capacitance in contact with the outside of the packaging material. CONSTITUTION:A capacitance meter is brought into contact with the bottom part of a packaging material 2 filled up with contents 1, from the outside, and internal capacitance of the packaging material 2 is measured. For instance, polyethylene resin pellets of diameters 2 to 5mm are filled up in a flexible container bag (of which the material is polyvinyl chloride, the thickness about 1mm and the internal capacity 1 to 2m<3>) as the packaging material 2. In the case where an electrode by which the capacitance measured form the bottom part of the flexible container bag is made 0.1 to 0.2pF when the resin pellets are dried is used, the indication output rises and shows 4 to 6pF when the surfaces of the resin pellets are in a wet state. When the resin pellets are immersed in water (the depth of the water is 0.1mm), an indication of 10pF or above is shown. At the time when the level of output from the capacitance meter is a prescribed level or above, an indication alarm device (a lamp 10, a buzzer 15) operates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring moisture inside a packaging material without opening or damaging the packaging material.

[0002]

2. Description of the Related Art Packaging materials for storing and transporting resin products, agricultural products, foods, etc. as contents are
Water may be mixed into the inside due to insufficient draining or drying after washing, or intrusion of rainwater during outdoor storage. If the contents inside the packaging material contain water, a troublesome operation of re-drying may be necessary, and in some cases, the commercial value may be lost at all. When resin pellets or powder is used as the content, if it contains moisture, it may cause serious troubles such as poor appearance and mechanical property deterioration when subjected to molding and processing. Management is also important industrially. However, conventionally, only a method of inserting a moisture meter inside the packaging material or taking out the content and checking for the presence of water is performed, and a simple method for efficiently measuring the moisture inside the packaging material is Was not known.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently measuring the water content inside a packaging material without opening or damaging the packaging material.

[0004]

As a result of intensive studies, the present inventor has found that the above problems can be solved by measuring the electrostatic capacity inside the packaging material, and has completed the present invention. That is, the present invention, the moisture inside the packaging material,
A method for measuring water content inside a packaging material, which comprises measuring with a capacitance meter contacting the outside of the packaging material.

In the present invention, the water content inside the packaging material is measured by a capacitance meter. This will be described below.
All substances have unique electrical characteristics, and the capacitance of the contents inside the packaging material is expressed by the following formula. C = C ₀ · ε _S (where C is the capacitance of the contents, C ₀ is the capacitance in vacuum (or in air), and ε _S is the relative permittivity of the contents.) Water Has a dielectric constant of about 80, whereas the relative dielectric constant of contents such as resin pellets in a dry state is usually 1 to 3.
It is a degree. Therefore, when water enters the inside of the packaging material, the capacitance of the contents rapidly increases, and the moisture content can be measured by detecting the difference from the dry state.

The method of the present invention can be applied to the contents having a relative dielectric constant of 50 or less in a dry state. In particular,
It can be preferably applied to those of 30. Specific examples of applicable contents include polyethylene, polypropylene,
Examples thereof include synthetic resins such as polyvinyl chloride and polystyrene. These may be applied in any shape such as powder or pellet, but usually, those having a diameter of about 100 mm or less are preferably applied.

The material of the packaging material may be a non-conductive material, and any material such as resin, cloth or paper can be used without particular limitation.

The thickness of the packaging material is 15 mm or less, preferably 10 mm or less. If the thickness exceeds 15 mm, the measurement sensitivity decreases. The lower limit of the thickness is not particularly limited,
Usually, the one having a thickness of 0.001 mm or more is used.

Further, as the capacitance meter, a commercially available one having a capacity of about 0.5 to 1000 PF can be applied, and the electrode thereof may be circular, elliptical or comb-teeth-shaped depending on the shape of the packaging material. used.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings. FIG. 1 illustrates a method for measuring the water content inside a packaging material for packaging resin pellets as contents. In the figure, a capacitance meter is brought into contact with the bottom of the packaging material 2 filled with the content 1 from the outside to measure the capacitance inside the packaging material. For example, when a flexible container bag (material: polyvinyl chloride, thickness: about 1 mm, internal volume: 1 to 2 m ³ ) as a packaging material is filled with polyethylene resin pellets with a diameter of 2 to 5 mm, The capacitance measured from the bottom of the bag changes as follows depending on the water content of the contents. In the case of an electrode having a capacitance of 0.1 to 0.2 pF when the resin pellet is dry,
When the surface of the resin pellet is in a wet state, the indicating output increases and shows 4 to 6 pF. When the resin pellet is immersed in water (water depth 0.1 mm), an instruction of 10 pF or more is shown.

As described above, the capacitance varies greatly when the resin pellets are in a dry state and when they are in a wet state. By configuring the system so that the alarm buzzer is activated when the output level from the capacitance meter becomes equal to or higher than a predetermined level, an extremely simple and highly accurate water measuring method can be obtained.

As an example of such a system, a portable moisture measuring device can be constructed by connecting a small electrode with an amplifier and an indicator / alarm device (lamp, buzzer) (FIG. 3). Alternatively, the capacitance meter may be fixed, and the packaging material may be continuously passed over the capacitance meter to continuously measure the water content in the packaging material (FIG. 4).

[0013]

EFFECT OF THE INVENTION Without opening or damaging the packaging material,
The moisture inside the packaging material such as FIBC can be measured very easily and efficiently.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of a moisture measuring device of the present invention.

FIG. 2A is a side view showing a configuration of an electrode. FIG. 3B is a plan view showing the structure of the electrode.

FIG. 3 is a diagram showing a configuration of a portable moisture measuring device.

FIG. 4A is a diagram showing a configuration of a continuous moisture measuring device. (B) It is a top view which shows the structure of a roller electrode.

[Explanation of symbols]

1: Resin pellet, 2: Packaging material, 3: Electrode, 4: Electronic circuit part, 5: Indicator / alarm device, 6: Cable, 7: Power supply,
8: Alarm unit, 9: Indicator, 10: Lamp, 1
1: buzzer, 12: indicator, 13: roller conveyor, 14: roller electrode, 15: spacer, 16: cover, 17: handle

Claims (2)

[Claims] 1. A method for measuring moisture inside a packaging material, characterized in that the moisture inside the packaging material is measured by a capacitance meter in contact with the outside of the packaging material. 2. The moisture measuring method according to claim 1, wherein the packaging material contains therein a content having a relative dielectric constant (ε _S ) of 50 or less when dried.