JPH08141100A - Fireproof sheet for flexible cable - Google Patents

Abstract

PURPOSE: To improve the fire resistance and heat insulating characteristic of a fireproof sheet by laminating a front side composite sheet consisting of metallic foil and glass cloth, a ceramic fiber blanket, metallic foil, a fire-retardant plastic foamed sheet and a rear side composite sheet consisting of metallic foil and fire-retardant paper or glass cloth in this order. CONSTITUTION: This waterproof sheet 1 is formed by laminating the front side composite sheet 2, the ceramic fiber blanket 5, the intermediate aluminum foil 6, the fire-retardant polyethylene foamed sheet 7 and the rear side composite sheet 8 in this order. The front side composite sheet 2 is formed by sticking the glass cloth 4 to the aluminum foil 3 and laminating the aluminum foil 3 on the outer side. The rear side composite sheet 8 is formed by sticking the glass cloth 10 to the aluminum foil 9 and laminating the aluminum foil 9 on the outer side. The respective layers 2 to 10 are preferably joined by adhesives. The fire-retardant paper may be used in place of the glass cloth 10 for the front side composite sheet 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fireproof sheet used for fireproofing a flammable cable.

[0002]

2. Description of the Related Art Cables such as telecommunication cables, optical communication cables and electric power cables generally use a flammable material such as polyethylene for an insulator, a protective coating or a sheath, so that when a fire occurs, the longitudinal direction of There is a risk of spreading fire.

For this reason, conventionally, a fireproof sheet is wound around a flammable cable to perform fireproofing. A conventional fireproof sheet is a composite sheet in which a glass cloth is bonded to an aluminum foil is laminated on both sides of a ceramic fiber blanket (JIS R3311) which is a fireproof heat insulating material, with the glass cloth facing outward. Since the ceramic fiber blanket has a weak bonding force between the ceramic fibers and the ceramic fibers on the surface are easily separated, the conventional fireproof sheet has a configuration in which both sides of the ceramic fiber blanket are protected by the composite sheet.

[0004]

Since the conventional fireproof sheet secures the necessary heat insulation performance by the thickness of the ceramic fiber blanket, the higher the required heat insulation performance is, the thinner the thickness of the ceramic fiber blanket becomes. Either the thickness must be increased or the number of wrapping layers of the fire protection sheet must be increased. However, the conventional fireproof sheet has a drawback that the cost is high because an expensive ceramic fiber blanket is used as the fireproof heat insulating material.

Therefore, recently, as a means for preventing the spread of flammable cables, it has been considered to wind a heat-foaming fireproof net around the cables. This fireproof net is made by applying a heat-foaming paint to the net body made of a fireproof material such as glass fiber thread by the dipping method (manufactured and sold by Herberts GmbH in Germany). The heat-foaming paint foams 30 to 40 times when heated by a flame and carbonizes to form a good fireproof heat insulating layer.

This fireproof net is wrapped around a flammable cable and subjected to a fire resistance test (850 ° C x 850 ° C).
According to the result of 20 minutes), it was confirmed that the winding of the fireproof net was effective in preventing the spread of the flammable cable. However, just by winding a fireproof net, the insulation resistance between the insulating cores decreases within 10 minutes after the flame is applied, and the function as a cable (communication function,
It became clear that the power transmission function) could not be maintained.

In the case of fireproofing a cable, it is not enough to simply have a fire spread prevention effect, and it is required that the function of the cable can be maintained for a certain time (usually 20 minutes or more) while being exposed to the flame. To be done.

In view of the above problems, it is an object of the present invention to provide a fireproof sheet for a flammable cable which can obtain the required fire resistance and heat insulation and is relatively inexpensive.

[0009]

In order to achieve this object, the fireproof sheet for a flammable cable of the present invention comprises:
A front composite sheet made by bonding glass cloth to a metal foil, a ceramic fiber blanket, and a metal foil,
It is characterized in that a flame-retardant plastic foam sheet and a back side composite sheet obtained by laminating flame-retardant paper or glass cloth on a metal foil are laminated in this order (Claim 1).

In the fireproof sheet of the present invention, the metal foil between the ceramic fiber blanket and the flame-retardant plastic foam sheet can be replaced with a composite sheet obtained by laminating flame-retardant paper or glass cloth on the metal foil. In that case, it is desirable to direct the metal foil to the ceramic fiber blanket side (claim 2).

As the flame-retardant plastic foam sheet,
A flame-retardant polyethylene foam sheet, a melamine resin foam sheet or the like can be used, but it is particularly preferable to use a flame-retardant polyethylene foam sheet (claim 3). Further, as the metal foil, it is preferable to use an aluminum foil which has good heat reflectivity and is lightweight.

In the fireproof sheet of the present invention, the ceramic fiber blanket and the flame-retardant plastic foam sheet constitute a heat insulating layer. Flame-retardant plastic foam sheets have lower heat resistance than ceramic fiber blankets,
It is not as hot as a ceramic fiber blanket because it is shielded from the flame by the ceramic fiber blanket and metal foil. Therefore, even if the heat resistance is low, it is less likely to be thermally damaged.

When the fireproof sheet of the present invention is used, the heat-reflecting property of the metal foil of the front composite sheet, the fire-proof heat insulating property of the ceramic fiber blanket, the heat-reflecting property of the intermediate metal foil, and the flame-retardant plastic foam sheet. Due to the heat insulating property and the heat reflecting property of the metal foil of the back side composite sheet, the temperature rise of the internal cable is suppressed, and at least 2 when the flame hits.
The function as a cable can be maintained for 0 minutes.

In the fireproof sheet of the present invention, the thickness of the ceramic fiber blanket can be reduced by the amount of the flame retardant plastic foam sheet used, and the flame retardant plastic foam sheet is cheaper than the ceramic fiber blanket. Therefore, the cost is low as a whole.

When a flame-retardant polyethylene foam sheet is used as the flame-retardant plastic foam sheet, a phenomenon in which the temperature rise due to heating temporarily stagnates midway and the temperature rise takes a long time. Therefore, it is particularly preferable.

[0016]

1 shows an embodiment of the present invention. The fireproof sheet 1 includes a front composite sheet 2 obtained by laminating a glass cloth 4 on an aluminum foil 3, a ceramic fiber blanket 5, an intermediate aluminum foil 6, a flame-retardant polyethylene foam sheet 7, and an aluminum foil 9 with a glass cloth. The back side composite sheet 8 in which 10 are stuck together is laminated in this order. The front composite sheet 2 and the back composite sheet 8 are laminated with the surfaces of the aluminum foils 3 and 9 facing outward. It is desirable to bond the layers with an adhesive.

In the laminated structure shown in FIG. 1, the thickness of the aluminum foil 3 on the front side is 20 μm, the thickness of the ceramic fiber blanket 5 is 6 mm, the thickness of the intermediate aluminum foil 6 is 50 μm, and the flame-retardant polyethylene foam sheet 7 is formed. A fireproof sheet having a thickness of 6 mm and a backside aluminum foil 9 having a thickness of 20 μm was manufactured as a prototype.

This fireproof sheet was wrapped around a cable to carry out a fire resistance test. The fire resistance test is to set a cable wound with a fireproof sheet in a vertical open tray and apply a flame of a gas burner for 20 minutes according to the regulations of IEEE383. The cable used for the test is a polyethylene insulation / polyethylene sheath communication cable (PEC ・ H 0.9 × 200
Pair). The fireproof sheet was wound around the cable with the front composite sheet 2 facing outward. A temperature detector was set between the fire protection sheet and the cable to check the temperature rise of the cable during the test. In addition, the insulation resistance of the insulated core wire pair inside the cable was measured to check the maintenance of the communication function.

In this fire resistance test, it was confirmed that even if a burner flame was applied for 20 minutes, the cable did not burn and flame spread could be prevented. Further, it was found that the insulation resistance did not decrease at all even after 20 minutes had passed since the start of applying the flame, and the function as a cable could be sufficiently maintained. The maximum temperature of the cable was 191 ° C. The appearance of the cable sheath after the test was almost good, although there was evidence of melting.

The temperature change of the cable was as shown in FIG. From this change in temperature, it can be seen that the temperature rises rapidly to a certain level and then drops or levels off. If such a temperature change is obtained, it is possible to make the cable temperature rise for a time, which is extremely effective for protecting the cable within a limited time (20 minutes) after the flame starts to hit.

It is considered that the reason why such a temperature change is obtained is that the flame-retardant polyethylene foam sheet 7 is used. That is, the flame-retardant polyethylene foam sheet 7
Contains a hydroxide such as aluminum hydroxide and generates water when heated. However, in the laminated structure of the present invention, the flame-retardant polyethylene foam sheet 7 is sandwiched between the aluminum foils 6 and 9 on both sides, and the foam form of the flame-retardant polyethylene foam sheet 7 is closed cells. It is difficult to escape to the outside. Moisture is generated in the flame-retardant polyethylene foam sheet 7, and the moisture is absorbed by the aluminum foils 6 and 9.
Since it absorbs heat while staying in the layer sandwiched between
It is considered that a peculiar temperature change is obtained in which the temperature rise does not continue and stays halfway.

FIG. 3 shows another embodiment of the present invention. This fireproof sheet 1 is different from the embodiment of FIG. 1 in that the back side composite sheet 8 is formed by laminating a flame-retardant paper 11 on an aluminum foil 9, and the aluminum foil 9 is attached to the flame-retardant polyethylene foam sheet 7.
That is, they are stacked toward the side. Since the other structure is the same as that of the fireproof sheet of FIG. 1, the same reference numerals are given to the same portions. With such a structure, it is possible to obtain the same fireproof heat insulation performance as the fireproof sheet of FIG.

FIG. 4 shows still another embodiment of the present invention.
This fireproof sheet 1 is different from the embodiment of FIG. 1 in that an intermediate composite sheet 12 obtained by laminating a flame-retardant paper 14 on an aluminum foil 13 is sandwiched between a ceramic fiber blanket 5 and a flame-retardant polyethylene foam sheet 7. 13 is laminated toward the ceramic fiber blanket 5 side. Since the other structure is the same as that of the fireproof sheet of FIG. 1, the same reference numerals are given to the same portions.

In this laminated structure, the aluminum foil 13 of the intermediate composite sheet 12 has a thickness of 20 μm, and the other layers have a thickness of FIG.
The same fire protection sheet as in the above example was manufactured. The fireproof sheet was wrapped around a cable and the same fire resistance test as in FIG. 1 was conducted. As a result, it was confirmed that this fireproof sheet could prevent the spread of fire, and the maximum temperature of the cable was 145 ° C. Further, it was found that the insulation resistance of the cable did not decrease at all even after 20 minutes had passed since the start of applying the flame, and the function as the cable could be sufficiently maintained. The appearance of the cable sheath after the test was almost good with little melting. The temperature change of the cable was as shown in FIG. In this case as well, it was confirmed that the temperature had a tendency to rise rapidly to a certain level and then decrease or level off.

In each of the above embodiments, the front composite sheet 2 is
Although the aluminum foil 3 is laminated outward, the front composite sheet 2 may be laminated with the glass cloth 4 outward. Even with this laminated structure, the fire resistance performance hardly changes.
However, when the glass cloth 4 is turned to the outside, it gives a tingling sensation to the operator who handles the fireproof sheet and makes it difficult to wind around the cable. Therefore, the front side composite sheet has the aluminum foil 3 turned to the outside as in the embodiment. It is preferable to stack them.

In the examples, a flame-retardant polyethylene foam sheet was used as the flame-retardant plastic foam sheet, but a melamine resin foam sheet or the like can be used as the flame-retardant plastic foam sheet. However, the flame-retardant polyethylene foam sheet is superior to other flame-retardant plastic foam sheets because it has the effect of delaying the temperature rise during heating when metal foils are laminated on both sides.

[0027]

As described above, if the fireproof sheet of the present invention is wrapped around a cable, it is possible to prevent the spread of the cable when a fire occurs and to function as a cable for a certain time (at least 20 minutes or more). Can be maintained. Therefore, it has a remarkable effect in preventing the spread of fire, securing information transmission function in case of fire, and securing lighting. Further, since the fireproof sheet of the present invention has a structure in which the flame-retardant plastic foam sheet plays a part of the heat insulating action, the thickness of the ceramic fiber blanket can be made thin and the cost is low. Although the flame-retardant plastic foam sheet has lower heat resistance than the ceramic fiber blanket, it is hard to be damaged by heat because it is in a position shielded from the flame by the ceramic fiber blanket and metal foil, and it can exhibit a sufficient heat insulation function. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a fireproof sheet according to the present invention.

FIG. 2 is a graph showing the temperature rise of the cable when the fireproof sheet of FIG. 1 is wrapped around the cable and a fire resistance test is performed.

FIG. 3 is a sectional view showing another embodiment of the fireproof sheet according to the present invention.

FIG. 4 is a cross-sectional view showing still another embodiment of the fireproof sheet according to the present invention.

FIG. 5 is a graph showing the temperature rise of the cable when the fireproof sheet of FIG.

[Explanation of symbols]

 1: Fireproof sheet 2: Front composite sheet 3: Aluminum foil 4: Glass cloth 5: Ceramic fiber blanket 6: Aluminum foil 7: Flame-retardant polyethylene foam sheet 8: Back composite sheet 9: Aluminum foil 10: Glass cloth 11: Difficulty Fuel paper 12: Intermediate composite sheet 13: Aluminum foil 14: Flame-retardant paper

Claims (3)

[Claims] 1. A front composite sheet comprising a metal foil and a glass cloth bonded together, and a ceramic fiber blanket,
A fireproof sheet for a flammable cable, which is obtained by laminating a metal foil, a flame-retardant plastic foam sheet, and a backside composite sheet obtained by laminating flame-retardant paper or glass cloth on the metal foil in this order. 2. A front composite sheet obtained by laminating a glass cloth on a metal foil, and a ceramic fiber blanket,
Intermediate composite sheet with metal foil laminated with flame-retardant paper or glass cloth, metal foil facing ceramic fiber blanket side, flame-retardant plastic foam sheet, and back-side composite sheet with metal foil laminated with flame-retardant paper or glass cloth A fireproof sheet for flammable cables, characterized in that and are laminated in this order. 3. The fireproof sheet for a flammable cable according to claim 1, wherein the flame-retardant plastic foam sheet is a flame-retardant polyethylene foam sheet containing hydroxide.