JPH04232044A - Pliable sheet and protective enclosure product - Google Patents

Abstract

PURPOSE: To improve a security of penetrating via a small diameter radiating energy by detecting using electric characteristics by a monitor according to a flow of a low melting point substance flowing via holes of an insulating substance formed by a cutting means. CONSTITUTION: Conductive low melting point substance layers 12, 13 are formed of flexible insulating substance layer 11 adhered to opposed surfaces, are solid at ambient temperature, but made fluid by energy of a cutting means using a small diameter radiating energy. Accordingly, when the layers 11, 12 are connected to a monitoring circuit, a change of using electric characteristics can be detected by a flow of the substance fluidized via holes of the layer 11 formed by the cutting means. Thus, safety to penetration of the energy like a laser beam is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible sheet suitable for making a safety enclosure for articles, and a safety enclosure made using the sheet.

0002

BACKGROUND OF THE INVENTION Flexible sheets suitable for making safety enclosures are already known, for example from European Patent No. 8930603.
The specification of No. 5 describes that the sheet includes a conductive member, and a monitor circuit is connected to the conductive member to detect interference caused by an external force that penetrates the sheet. Although this known sheet provides security against penetration by small diameter perforating means such as a needle, it is desired to provide security against penetration by small diameter radiant energy cutting means such as a laser beam.

0003

SUMMARY OF THE INVENTION It is an object of the present invention to provide a flexible sheet suitable for making a safety enclosure for an article and a safety enclosure made from such a sheet.

0004

According to the present invention, there is provided a flexible sheet for forming a safety enclosure for an article, comprising a layer of flexible insulating material having a layer of conductive low-melting material adhered to each opposing surface. The conductive low melting point material is solid at ambient temperature, but is turned into a fluid by the energy produced by the cutting means using small diameter radiant energy, so that when the conductive low melting point material layer is connected to a monitoring circuit, it will remain solid during use. A flexible sheet is provided, characterized in that a change in the electrical properties of the flexible sheet is detectable by the flow of the fluidized conductive low melting point material through the pores in the layer of insulating material formed by the cutting means.

Preferably, the thickness of each conductive low melting point material layer is approximately the same as or slightly thicker than the insulating material layer, and each layer is less than 25 μm thick. Conveniently, each conductive low melting point material layer has a thickness of 8 to 12 μm.
The thickness of the insulating material layer is approximately the same. Preferably, the conductive low melting point material is fluidized at about 100°C. Preferably, the layer of insulating material consists of polyester and each layer of conductive low melting point material consists of carbon-filled polyester, the latter being applied to the former by screen printing. Typically, carbon-filled polyester contains graphitic carbon.
0% filling to provide a resistivity of 0.3 Ω-cm. Other materials can also be used to form the conductive low melting point material, such as thermoplastics filled with carbon or conductive salts (such as cesium iodide), such as polyimides, polyethers, polyurethanes, polyvinyl acetate, Certain uncured silicones and the like can be used. Mainly, these substances are of low molecular weight and are heated between 70 and 130 °C.
Fluidizes at temperatures in the range of .

Preferably, the sheets of the present invention include a jacket adhered to a layer of electrically conductive low melting point material. The outer jacket consists of carbon-filled polyester coated with a polyester film;
Its carbon content, high jetness, and high resistance (preferably 1013 Ω-cm or higher)
Therefore, it can be selected to provide a minimal change in electrical resistance upon penetration or fluidization. The jacket can be adhered to each layer of conductive low melting material with an adhesive, such as polyester, to provide a patterned jacket covering a sufficient area for laminating the sheets. The adhesive layer can be printed on top of the low melting point material.

According to another aspect of the invention, there is provided a flexible sheet suitable for use in creating a safety enclosure for an article, the sheet comprising two layers of flexible insulating material separated by a layer of flexible insulating material. It consists of electrically responsive fibrous material layers, each flexible fibrous material layer being adhered to substantially the entire surface of a flexible insulating material layer with a flexible electrically responsive adhesive layer, the adhesive layer being in a matrix of low melting point material at ambient temperature. The fiber length of the fibrous material is greater than the thickness of the adhesive and insulating material layers.

Preferably, each layer of low melting point material is approximately the same or slightly thicker than the insulating layer, and each layer has a thickness of less than 25 μm. For convenience, each low melting point layer has a thickness of 8 to 12 μm, and the insulating layer has a thickness of approximately the same. Preferably, the low melting point material is fluidized at about 100°C. Preferably, the insulating layer consists of a polyester film, each low melting point material layer consists of carbon-filled polyester,
The latter can be applied to the insulating layer by screen printing and overprinted with an adhesive such as polyester to provide a patterned covering of low melting point material of sufficient area to laminate the sheets. Typically, carbon filled polyester is 50% filled with graphitic carbon providing a resistivity on the order of 0.3 ohm-cm.

Preferably, the fibrous material layer has a resistance of 1 to 10 Ω-
It consists of unsintered carbon-filled PTFE with a volume resistivity in the range of cm and a thickness on the order of 75 μm. Preferably, the sheet includes a jacket adhered to the fibrous material layer with a non-conductive adhesive. This adhesive can be printed onto the fibrous material layer, may be polyester, and provides a patterned covering of sufficient area to laminate the sheets. The jacket consists of a carbon-filled polyester coated with a polyester film, which reduces the electrical resistance upon penetration or fluidization due to its high jetness and high resistance (preferably greater than 1013 Ω-cm). It may be selected to provide the minimum amount of change.

According to another aspect of the invention, there is provided a safety enclosure made of the above-described flexible sheet according to the invention, each layer of low melting point material being connected to an electrical monitoring circuit. The monitor circuit can be a bridge circuit that monitors impedance. By providing a layer of low melting material containing carbon or other conductive filler, the sheets and enclosures provided by the present invention provide security against penetration by radiation energy cutting means such as a laser beam.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described with reference to the drawings. Each of the flexible sheets 10 shown unfolded in FIG. Layers 14, 15 are jackets that are substantially insulating layers. Layer 11 is made of polyester, with a thickness of about 12 .mu.m giving best results, but less than 25 .mu.m may be sufficient. Layers 12, 13 are printed on either side of layer 11 and are approximately 8-25 μm thick. layers 12, 13
each consists of a polyester containing graphitic carbon at a level of about 50% by weight to make layers 12, 13 electrically conductive, and with a melting point of 100° C. to provide low melting properties to layers 11, 12. We use custom-made polyester. The outer sheaths 14 and 15 are also made of carbon-filled polyester and are coated on the polyester base material.
This filling is selected to provide very high resistivity (greater than 10 13 Ω-cm) and high blackness. The outer covering 14,15 is adhered to the layers 12,13 with an adhesive such as polyester printed on the layers 12,13 to provide a patterned covering covering about 30% of the area. With this construction, sheet 10 is a laminate, with layers 12, 13 essentially homogeneous and perfect over their entire area. The area of layer 12 is substantially the same as the area of layer 13, both of which are slightly less than the area of layer 11 to provide insulation at the ends of layers 12,13.

FIG. 2 shows a partially completed safety enclosure 20 made of sheet 10. A sheet layer 11 is first formed into the shape of a box material, and the formed sheet is folded along a line 21 to form a box-like shape that encloses or encloses an item (not shown) to be protected. It is. Adjacent ends 22 of the folded sheet 10 can be joined or overlapped and may be held together with cover tape (not shown). An electrical monitoring circuit 23 is connected to the enclosure 20 to provide an impedance monitor across the insulating layer 11 with conductive layers 12, 13 acting as conductive end pads. Circuit 23 connects layers 12, 13 via copper conductor strips.
It is connected to the.

FIG. 3 shows a flexible sheet 30 in a modified form,
This sheet 30 includes all the components of sheet 10, but also includes a layer 3 of electrically responsive fibrous material, preferably carbon-filled green PTFE, between layers 14, 15 and 12, 13.
Contains 1,32. The fibers of layers 31, 32 are of sufficient length to extend from one layer 31, 32 to the other when penetrated by the perforating means. layers 31, 32
is secured to both layers 14, 15 and 12, 13 with a polyester adhesive, the adhesive in a pattern giving approximately 30% coverage. Therefore, layers 31 and 32 are layer 1
2,13 and can be used as wiring between layers 12,13 and the monitor circuit 23 of FIG. 2, thereby eliminating the copper conductor strip. In use, this has the advantage that only one monitoring circuit is required for both layers 12, 13 and layers 31, 32 (which serve as a security measure against perforation).

[Brief explanation of the drawing]

FIG. 1 is an exploded view of a first form of flexible sheet used to create a safety enclosure.

FIG. 2 is a conceptual diagram of a partially completed safety enclosure made from the sheets of FIG. 1;

FIG. 3 is an exploded view of a second form of flexible sheet used to create a safety enclosure.

[Explanation of symbols]

10...Flexible sheet 11...Insulating layer 12, 13...Electroconductive layer 14,15... Outer cover 20... Safety enclosure 21...Polyline 22…Joint part 23...Monitor circuit 30...Flexible sheet 31, 32...Electrically responsive fiber material layer.

Claims (9)

[Claims] Claims: 1. A flexible sheet for creating a safety enclosure for an article, comprising a layer of a flexible insulating material having a layer of a conductive low-melting material adhered to each side, the low-melting material being solid at ambient temperature. However, since it is made into a fluid by the energy of the cutting means using small-diameter radiant energy, when the low melting point material layer is connected to a monitoring circuit, the change in electrical properties during use will be caused by the insulating material formed by the cutting means. A flexible sheet characterized in that it is detectable by the flow of a fluidized low melting point substance through the pores in the layer. 2. The flexible sheet of claim 1, wherein the thickness of each of said low melting point material layers is approximately the same as or slightly thicker than the thickness of said insulating material layer. 3. The flexible sheet of claim 1, wherein said low melting point material layer comprises carbon filled polyester applied to said insulating layer by screen printing. 4. The flexible sheet of claim 3, further comprising a jacket adhered to the layer of low melting point material. 5. The flexible sheet according to claim 4, wherein the outer cover is carbon-filled polyester coated on a polyester film. 6. A flexible sheet suitable for creating a safety enclosure for an article, said flexible sheet comprising two layers of flexible electrically responsive fibrous material separated by a layer of flexible insulating material, each layer comprising: The flexible electro-responsive fibrous material layer is adhered to substantially the entire surface of the flexible insulating material layer with a flexible electro-responsive adhesive layer in a matrix of low melting material at ambient temperature. 1. A flexible sheet comprising a layer of carbon bonded to each other, wherein the fiber length of the flexible electroresponsive fibrous material is greater than the thickness of the flexible electroresponsive adhesive and the flexible insulating material layer. 7. The flexible sheet of claim 6 further comprising a jacket adhered to said fibrous material layer with a non-conductive adhesive. 8. The outer covering is of a high tone (jetnes).
8. The flexible sheet of claim 7, wherein the flexible sheet is a carbon-filled polyester having a carbon content selected to provide s) and minimal change in electrical resistance upon penetration or flow due to its high resistance. Claim 9: Solid at ambient temperature, but with a content of about 100%
A flexible sheet consisting of a plurality of layers including an insulating material layer each having a layer of an electrically conductive low-melting material adhered to each side of the conductive material that becomes fluid at a temperature of 0.degree. and an electrical monitoring circuit connected to the layer.