JP3137591B2 - Inspection method for bonding part of sheet having conductive layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a joint of a sheet having a conductive layer, and more particularly to a joint of a sheet having a conductive layer in a high-density polyethylene sheet used for impermeable construction at a waste disposal site. The present invention relates to an inspection method for inspecting the quality of a bonding state of a semiconductor device.

[0002]

2. Description of the Related Art Solid wastes, sludge, liquids and the like are dumped at waste disposal sites in a mixed state. Among these, there are various water-soluble contaminants that are dissolved by rainwater or the like. In order to prevent these contaminants from leaking to the outside ground and contaminating the surrounding ground, a water-blocking sheet is laid as a water-blocking work on the entire bottom surface of the disposal site. Generally, a high-density polyethylene sheet is used as the water-shielding sheet. The high-density polyethylene sheet is suitable as a water-impervious sheet because of its strong penetration resistance. However, the water-impervious sheet to be laid has a thickness of about 1.5 mm to 2 mm, which is a small hole when laid on the ground. Opening (pinhole) and tearing may also occur.

[0003] There has been proposed a detection device for detecting such holes or tears in the water-impervious sheet at an early stage, and a water-impervious sheet having a conductive layer for exhibiting the function of the detection device. FIG. 3 and FIG. 4 are explanatory diagrams showing an example of the configuration of a waste disposal site on which the impermeable sheet is laid, and a device for early detecting perforations, breaks, and the like of the impermeable sheet. This prior art is disclosed in Japanese Patent Application Laid-Open No. Hei 6-1000078. FIG. 3 shows the conductive layer 5 laid on the waste disposal site 50.
2 shows a configuration of a water-impervious sheet 51 having a 2 and a detecting device 60 for detecting breakage of the water-impervious sheet 51.

[0004] The water-blocking sheet 51 is a high-density polyethylene sheet integrally formed by three-layer simultaneous extrusion. The water impermeable sheet 51 has a three-layer structure as shown in an enlarged cross section in FIG. A white high-density polyethylene sheet is arranged on the surface layer 53. This white high-density polyethylene sheet constitutes a heat reflection layer. The intermediate standard layer 54 is provided with a high-density polyethylene sheet to which carbon black has been added. The intermediate standard layer 54 can obtain excellent weather resistance by adding carbon black. Further, on the lowermost layer 55, a high-density polyethylene sheet serving as the conductive layer 52 is disposed. That is, the lowermost layer 55 contains more carbon black than the intermediate standard layer 54. Carbon black is conductive fine particles, and when added at a predetermined density or more, the conductive layer 52 is formed.

In FIG. 3, a detecting device 60 includes a high-voltage DC power supply 61, a rubber pad 62 constituting a negative electrode, and a brass wire brush 63 serving as an inspection terminal constituting a positive electrode. A rubber pad 62 corresponding to the negative electrode of the detection device 60 is brought into contact with the conductive layer 52 and a high-voltage power supply 6
A negative voltage from 0 to about 15,000 to 35,000 V is applied. At this time, a negative charge is generated in the conductive layer 52 by the principle of electromagnetic induction. With the conductive layer 52 charged negatively, the brass wire brush 63 is slid so as to slide on the surface layer of the impermeable sheet 51. At this time, as shown in FIG.
If the water-impervious sheet 51 has a defect such as a pinhole or a tear of about 0.5 mm or more, the conductive layer 52 is inserted through the pinhole or the like.
Is generated between the lowermost layer 55 and the brass wire brush 63, and a high-pressure spark 70 is generated. This spark 7
A value of 0 can be visually checked, and an alarm (not shown) such as a buzzer can be sounded by detecting discharge. Thereby, the damaged portion of the water impermeable sheet 51 can be found. Thus, a technique for easily finding a defective portion of the water impermeable sheet 51 is disclosed.

Next, the joining of the waterproof sheet 51 will be described with reference to FIG. As shown in FIG. 5, the two high-density polyethylene sheets are overlapped in a band shape having a width L of about 10 cm to form an overlapping portion 56, and the overlapping portion 56 is joined by hot wedge. In the hot wedge bonding, a hot wedge (heat iron) (not shown) is brought into contact between the two sheets 51 in the overlapped portion so as to be sandwiched therebetween, and the sheet outer surface 51 is formed.
This is a joining method in which a joining portion is pressed from nip by a nip roll (not shown) and the facing hot-melted sheet surfaces are welded to each other. By using a double wedge having two rows of irons for the hot wedge, two parallel strip-shaped welds 57 are formed at the joint. An air channel 58 is formed between the two rows of welds by slightly swelling the sheet.

By the way, if the two rows of the welded portions are securely fused and adhered to each other, the air channel can be kept airtight by closing the open ports 59 at both ends. Utilizing this fact, a pressurization test has conventionally been performed to confirm the quality of the joint at the joint. In this pressurization test, as shown in FIG. 6, the open port 59 at the end of the joint is used as a compressed air supply port. The compressed air is supplied from the compression pump P from this portion to fill the air channel 58 with the compressed air, and thereafter, a change in the value of the pressure gauge G provided in the path is observed. If there is a defective joint, the compressed air leaks therefrom, so that the internal pressure changes and the value of the pressure gauge G changes. Thus, the quality of the fused state of the joint was determined.

[0008]

In the pressurization test shown in FIG. 6, air leakage from the air channel 58 is confirmed by a change in the value of the pressure gauge G. Can not. For this reason, it is necessary to perform an additional inspection such as a visual inspection in order to know where the defective portion is at the joint. Therefore, not only the time required for the inspection is increased, but also a large number of personnel are required for the inspection.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an inspection which can easily and accurately inspect the bonding state of a bonding portion of a waterproof sheet having a conductive layer. It is to provide a method.

[0010]

In order to achieve the above-mentioned object, the present invention provides a method of forming a thermoplastic resin sheet by mixing and molding conductive particles and forming a conductive layer in a lower layer. A method for inspecting the bonding condition of the sheet joints, wherein the sheet is welded by pressing from above and below the sheet so that a hot iron is sandwiched between the overlaps. A negative terminal of a power supply is connected to the conductive layer to apply a negative charge, and a test terminal serving as a positive electrode is moved along an end of the overlapping portion, and the conductive layer is connected to the conductive layer in a state where the junction is sandwiched. It is characterized in that the connection state of the joining portion is inspected by confirming the conduction with the end of the overlapping portion.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for inspecting a joint 2 of a waterproof sheet 1 having a conductive layer according to the present invention will be described with reference to FIG. As shown in FIG. 1, a detection device 10 similar to that shown in FIG. 4 is disposed at a joint 2 of a water-blocking sheet 1 made of a high-density polyethylene sheet that is a thermoplastic resin. In the inspection method according to the present embodiment, it is possible to inspect whether or not the joint of the joint 2 of the impermeable sheet 1 is good by using the detection device 10.

As shown in FIG. 1, a detecting device 10 comprises a high-voltage DC power supply 11, a rubber pad 12 for making a conductive layer a negative electrode, and a brass wire brush 13 as an inspection terminal for forming a positive electrode. ing. The negative electrode end of the high-voltage DC power supply is connected to the lowermost layer 4 of the waterproof sheet 1 via the rubber pad 12. On the other hand, the tip of the brass wire brush 13 constituting the positive electrode is positioned in contact with or slightly away from the end face 5a of the tab portion 5 formed by hot wedge bonding. At this time, the operation state of the detection device 10 differs depending on the joining state of the joining portion 2.

FIG. 2 shows an example of the joining state. FIG. 2A is an enlarged cross-sectional view showing an example in which good bonding has been performed. In hot wedge bonding, the surface of the sheet to be bonded is completely melted, and in this state, the welded portion 6 is pressed from the outer surface of the sheet by a nip roller (not shown).
The thin layer portion forming the conductive layer 3b is dispersed and flows to the periphery by the pressing force of the nip roller. As a result, the carbon black forming the conductive layer 3b is dispersed in the surrounding high-density polyethylene sheet, and the conductive layer 3b of the welded portion 6 disappears. Therefore, when such good hot wedge bonding is performed, since the conductive layer 3b disappears at the welded portion 6, the conductive layer 3c corresponding to the tab portion 5 has the charged water-impervious sheet 1 side. The conductive layer 3a is completely cut off and enters a non-charged state. Therefore, the high-voltage current does not leak to the brass wire brush 13 side.

On the other hand, as shown in FIG. 2B, when the joint 2 is not completely welded, the welds 6 are formed in a row in appearance and joined. I can see,
Since the conductive layer 3b remains as it is or in a thin layer, it is in an electrically conductive state. When the brass wire brush 13 is slid along the tab portion 5 in such a state, a high-voltage current leaks to the brush 13 of the detection device 10, and a spark 20 is generated between the brush 13 and the conductive layer. Spark 2
The occurrence of “0” confirms a defective bonding state of the bonding portion 2. Further, the occurrence of the spark 20 can be visually confirmed, and an alarm (not shown) such as a buzzer provided in the detection device 10 can be generated. Conventionally, the detecting device 10 used only for the general portion of the impermeable sheet 1
Are arranged as shown in FIG. 1 and inspected,
The quality of the bonding state of the hot wedge bonding portion 2 of the water impermeable sheet 1 can be easily and immediately confirmed.

Although the voltage applied to the detection device 10 is high, the current is very small. Therefore, the brass wire brush 13
Only the conduction state of the peripheral joint 2 can be confirmed. Therefore, a defective portion of the joint 2 can be immediately found by directly looking at a portion where a buzzer sounds or a spark is generated.

[0016]

As is apparent from the above description, according to the present invention, it is possible to easily and accurately determine whether or not the joining state of the joining portion of the waterproof sheet having the conductive layer is good. .

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a joined portion in which an embodiment of a method for inspecting a joined portion of a sheet having a conductive layer according to the present invention is enlarged.

FIG. 2 is a state explanatory view showing an example of a bonding state of a bonding portion of a sheet having a conductive layer.

FIG. 3 is an overall configuration diagram showing a conventional example in which a waterproof sheet having a conductive layer is laid at a waste disposal site and the waterproof sheet is inspected.

FIG. 4 is a partially enlarged cross-sectional view showing an inspection state of a perforated defect of the water impermeable sheet.

FIG. 5 is an explanatory diagram showing an enlarged view of a hot wedge joint portion 2 of a water impermeable sheet.

FIG. 6 is an explanatory view showing an outline of a pressurization inspection of a hot wedge joint portion 2 of a water impermeable sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waterproof sheet 2 Joining part 3, 3a, 3b, 3c Conductive layer 4 Lowermost layer 5 Tab part 10 Detector 11 High voltage power supply 12 Rubber pad 13 Brass wire brush 20 Spark

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-309916 (JP, A) JP-A-9-243581 (JP, A) JP-A-6-100078 (JP, A) JP-A-47-107 13992 (JP, A) Actually open sho 59-144031 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 27/92 G01N 27/20

Claims (1)

(57) [Claims] 1. A thermoplastic resin sheet formed by mixing and molding conductive particles and forming a conductive layer as a lower layer is overlapped with each other in a band shape having a predetermined width to form an overlapping portion, and a hot iron is sandwiched between the overlapping portions. An inspection method for inspecting the bonding state of the bonding portion of the sheet by pressing the upper and lower surfaces of the sheet to weld the overlapped portion, wherein a negative electrode of a power supply is connected to the conductive layer. And applying a test terminal serving as a positive electrode along the edge of the overlapping portion, and confirming conduction between the conductive layer and the edge of the overlapping portion while sandwiching the bonding portion. A method for inspecting a joint portion of a sheet having a conductive layer, comprising: inspecting a joining state of the joint portion.