JP5783832B2 - Flame retardant sheet and curing sheet for nuclear power plant - Google Patents

Description

  The present invention relates to a flame-retardant sheet excellent in transmission visibility (hereinafter sometimes referred to as “transparency”). More specifically, the present invention relates to a flame retardant sheet that is excellent in flame retardancy and transparency, does not generate harmful gas during incineration, and has low ash content after incineration.

  Conventionally, curing sheets used for construction and construction (so-called machinery, sheets for covering shelves, ceilings, walls, floors, etc.) include fibers such as plastic films such as polyester, polyamide, polyolefin, and polyurethane. No resin sheet is used.

  Such a sheet is used not only as a curing sheet for construction and construction but also as a curing sheet for a nuclear power plant. For example, when a radioactive material handling facility such as a nuclear power plant performs construction or inspection of a radiation handling device, in order to prevent the equipment and peripheral parts of the facility from being contaminated by the radioactive material, The periphery is covered with the sheet to protect it. The sheet is removed after completion of construction and inspection.

  The nuclear power plant curing sheet is required to have flame retardancy equivalent to VTM-0 (hereinafter also referred to as V-0) in the flame retardancy test (thin material vertical combustion test) based on the UL-94 standard. . Further, the above sheet is required to have good incineration properties, and to reduce ash remaining after incineration. This is because the used sheet is contaminated with radioactive substances, and the ash remaining after incineration also contains a large amount of radioactive substances, so there is a problem that the environmental load becomes very high when the ash is processed. Because.

  Therefore, a flame retardant resin sheet is required, and a flame retardant resin sheet using a halogen-containing resin such as vinyl chloride or a flame retardant resin sheet in which a flame retardant is kneaded into the resin constituting the resin sheet. Is sold.

  However, a flame-retardant resin sheet using a halogen-containing resin such as vinyl chloride generates harmful gases such as chlorine gas and hydrogen chloride gas during a fire or incineration due to the vinyl chloride resin. For this reason, there is a possibility that health may be harmed by toxicity when a fire breaks out, which may cause damage to the incinerator during incineration and concern about the generation of dioxins. Therefore, when the sheet is finally disposed, it is disposed not only by incineration but also by landfill. Under such circumstances, the landfill site as the final disposal site is decreasing in recent years, and it is becoming difficult to secure a space for burying and discarding the sheet.

  In addition, the flame retardant resin sheet in which a flame retardant is kneaded into the resin is inferior in transparency because the entire sheet is white, cloudy, brown or black due to the flame retardant, etc. There was a problem that I could not watch. When a device or floor is covered with a sheet having poor transparency, the following problems occur. That is, it is difficult for the operator to recognize the size of the device, and inconveniences such as hitting a tool during the work are likely to occur. When the floor is covered, it is difficult to understand the unevenness of the floor surface, and it is easy for the operator to whisper. When a sheet is placed on a tool or the like, it is impossible to know where the tool or the like is. In particular, in radioactive material handling facilities, when using sheets to partition a control area that is highly contaminated with radioactive material, it is difficult to understand the state of the work inside, and the discovery of accidents and sudden illnesses by workers is delayed. End up.

  Therefore, such a sheet has the following conditions: flame retardancy, permeation visibility, no generation of harmful gases such as halogenated gas, and low ash content after incineration. Is required.

  Various studies have been conducted in order to obtain a sheet having the above conditions. For example, in order to reduce the ash content after incineration while avoiding the generation of halogenated gas such as hydrogen chloride gas, urethane resin and (iso) cyanuric acid derivative compound were contained on one or both sides of the base fabric. A flame retardant sheet in which a flame retardant layer containing a flame retardant resin composition is formed has been proposed (see, for example, Patent Document 1).

  In addition, as a flame retardant sheet that achieves flame retardancy at the V-0 level, a flame retardant plastic sheet formed of a composition containing an ethylene-vinyl acetate copolymer, red phosphorus, and melamine sulfate (for example, Patent Documents) 2), and a sheet formed of a composition in which a dicyandiamide is mixed with an aqueous dispersion of a polyolefin resin and / or an aqueous dispersion of a polyurethane resin, and a self-digestible material obtained by laminating a thermoplastic resin film. Flame retardant sheets (see, for example, Patent Document 3) have been proposed.

  The sheets described in Patent Document 1 to Patent Document 3 are not only flame retardant, but also contain no halogen compounds, so that generation of harmful gases during fires and incineration is suppressed, and the safety is high. is there. Moreover, the sheet | seat described in patent document 1-patent document 3 consists of the compound which consists of nitrogen, oxygen, carbon, and hydrogen, and since ash content hardly remains after incineration, it is useful.

  In addition to the above, as a fire-resistant sheet with reduced environmental load, flexible fire-ignition comprising a lactic acid-aliphatic ester copolymer and a hydrolyzable polyester resin different from the copolymer. A sheet in which a coarse woven fabric made of polylactic acid fiber is laminated on a flexible sheet or the flexible incombustible sheet has been proposed (for example, see Patent Document 4). Since the sheet described in Patent Document 4 is transparent or translucent, it has high transmission visibility, low ash content after incineration, and reduced environmental load. -Suitable for covering ceilings, walls, floors, etc.

  Furthermore, a mesh sheet in which a core-sheath-type multilayer monofilament containing a flame retardant is knitted and a through hole is formed between the filaments has been proposed (see, for example, Patent Document 5). The mesh sheet of Patent Document 5 is useful in that it has air permeability and further has a small amount of ash after incineration.

JP 2003-049367 A JP-A-10-182895 JP 2001-047567 A JP 2008-222789 A JP 2002-327353 A

However, the sheets obtained in Patent Documents 1 to 5 have the following problems.
The sheet | seat which does not contain the halogen element obtained by patent documents 1-3 is useful from a viewpoint of a flame retardance, generation | occurrence | production suppression of the harmful combustion gas at the time of a fire or incineration, and reduction of the ash content after incineration. However, since the flame retardant is contained in a large amount, the visible light permeability is inferior, and even if some visible light permeability is secured, the transparency is very poor.

  Further, in the case of Patent Document 4, the transparency is ensured, but since it hydrolyzes, there is a problem that the strength and durability of the material are remarkably poor and cannot be used for a long time. Further, the material is expensive because it is special.

  The mesh sheet obtained in Patent Document 5 is used to prevent the construction material from falling from the construction site, and has a fine mesh for ensuring ventilation in the construction site. ing. However, the mesh sheet is not suitable for applications that cover and protect machinery, shelves, ceilings, walls, floors, etc., at the construction site of the facility, because the mesh part is an open part.

  In view of these problems, the present invention seeks to provide a flame retardant sheet and a nuclear power plant curing sheet that have excellent transparency and flame retardancy, suppress the generation of harmful gases during incineration, and have low ash content after incineration. To do.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a flame retardant sheet comprising a flame retardant layer on a part of the surface of the substrate film is provided on one or both sides of the substrate film having transparency. The present inventors have found that it is excellent in strength, transparency, and flame retardancy, and can reduce harmful gases during incineration and ash residue during incineration.

That is, the gist of the present invention is as follows.
(1) A flame retardant layer containing a flame retardant and a synthetic resin binder is formed on one side or both sides of a base film having a haze value of 40% or less measured according to JIS K7105 (1981) which does not contain a halogen element. A flame retardant sheet provided by printing , wherein the area ratio of the flame retardant layer on the base film is 2 to 60 % .
(2) The flame retardant sheet according to (1), wherein the flame retardant is at least one selected from a nitrogen flame retardant, a phosphorus flame retardant, and a sulfur flame retardant.
(3) The flame retardant sheet according to (1) or (2), wherein the ratio of the flame retardant to the whole flame retardant sheet is 3 to 40% by mass.
(4) A nuclear power plant curing sheet using the flame retardant sheet according to any one of (1) to (3).

  The flame-retardant sheet of the present invention is excellent in flame retardancy, suppresses generation of harmful gases during combustion, reduces ash after incineration, and has high transparency. Therefore, workers can work safely and can be used suitably for construction sheets, curing sheets, windproof sheets, partition sheets, etc., especially as curing sheets used for inspection, repair, etc. in nuclear power plants and radioactive material handling facilities Useful.

It is the schematic of the flame-retardant sheet | seat of this invention in which a flame-retardant layer is provided in the lattice pattern on the base film. It is the schematic of the flame-retardant sheet | seat of this invention in which a flame-retardant layer is provided in many crosses of the vertical and horizontal arrangement on the base film. It is the schematic of the flame-retardant sheet | seat of this invention in which a flame-retardant layer is provided in many zigzag crosses on a base film. It is the schematic of the flame-retardant sheet | seat of this invention provided so that many flame retardant layers might connect the hexagon. It is the schematic of the flame-retardant sheet | seat of this invention in which a flame-resistant layer is provided so that a lattice pattern may become diagonal on a base film. It is the schematic of the flame-retardant sheet | seat of this invention in which a flame-retardant layer is provided so that many rhombus outline may be formed on a base film. It is the schematic of the flame-retardant sheet | seat of this invention in which a flame-retardant layer is provided so that it may become a polka dot pattern on a base film. It is the schematic of the flame-retardant sheet | seat of this invention in which a flame-retardant layer is provided so that it may become a checkered pattern on a base film.

Hereinafter, the present invention will be described in detail.
The flame retardant sheet of the present invention is obtained by providing a flame retardant layer on a part of a base film on one side or both sides of a base film having transparency.

  The flame retardant sheet of the present invention is preferably composed of a visible light transmitting portion and a flame retardant visible light opaque portion (hereinafter also simply referred to as a visible light opaque portion) when viewed from the surface of the flame retardant sheet. In addition, a visible light transmission part says the part whose haze value mentioned later is 40% or less, and a visible light impermeability part says the part where haze value mentioned later exceeds 40%. With such a configuration, the transmission visibility can be obtained by the visible light transmitting portion, and the flame retardance can be obtained by the flame retardant visible light non-transmitting portion. Therefore, a high level of transmission visibility and flame retardancy can be achieved. Specifically, it becomes possible to place a relatively high concentration of flame retardant in the flame retardant visible light impervious portion, and the flame retardant is kneaded into the resin component constituting the film, so that the entire sheet has flame resistance. Compared with the sheet formed, even if the amount of the flame retardant contained in the entire sheet is the same amount, a highly concentrated flame retardant can be partially disposed, so that excellent flame retardancy can be obtained. . In addition, the visible light transmitting portion can be configured to have a configuration in which the amount of the flame retardant is smaller than the average value of the amount of the flame retardant included in the entire sheet, or a configuration that does not include the flame retardant, so the transmission visibility is also very good. It is.

  The visible light impervious portion preferably has a laminated structure including a base film and a flame retardant layer as viewed from the cross section of the flame retardant sheet. With such a configuration, the base film can hold the flame retardant layer.

  The visible light transmissive part may be configured to include at least a base film, and the visible light transmissive part is more preferably composed of only the base film. With such a configuration, when the flame retardant sheet is exposed to flame, the base film constituting the visible light transmitting portion contracts due to heat, and the flame retardant visible light existing around the visible light transmitting portion. The impermeable portion (that is, the flame retardant layer) aggregates. As a result, the amount of the flame retardant in the portion exposed to the flame is temporarily increased, causing a phenomenon that the fire is extinguished. Moreover, the flame-retardant sheet | seat which has the especially outstanding transmission | permeability visibility can be obtained.

The flame retardant sheet of the present invention has a flame retardant layer in a part of the base film. That is, the part which has a flame retardance exists as a layer. With such a configuration, the base film is more easily combusted than the flame retardant layer due to the difference between the flame retardance of the base film and the flame retardance of the flame retardant layer. A phenomenon occurs in which the base film in the transmission part burns out and a part of the flame-retardant sheet is cut off and extinguished. From the viewpoint of obtaining such an effect more remarkably, a visible light opaque portion, it is necessary that the flame retardant layer is formed by printing on one or both surfaces of a substrate film.

  From the viewpoint of suppressing the generation of harmful gases during incineration, the base film needs to contain no halogen element. Specific examples of the base film include polyamide films such as 6 nylon and 66 nylon, and polyester films such as polyethylene terephthalate and polybutylene terephthalate. Of these, a polyamide film is preferably used from the viewpoint of excellent flame retardancy. In particular, when 66 nylon is used, the critical oxygen index is high and the flame retardancy is excellent.

  When a polyamide film is used as the base film, sufficient flame retardancy can be easily obtained as a whole of the flame retardant sheet due to the flame retardancy of the polyamide, and the amount of the flame retardant described later can be reduced. That is, since the desired flame retardancy can be maintained even if the amount of the flame retardant that impedes transmission visibility is reduced, the area of the visible light transmitting portion can be increased.

  The base film needs to be a film having a haze value of 40% or less as measured by JIS K7105 (1981), which is an index of transparency, from the viewpoint of ensuring transparency. A film that is 30% or less is preferred. If the film has such a haze value, the back side of the film should be seen from a distance when used for coating to prevent contamination of equipment, floors, etc. or for partitioning special areas. It is possible to prevent falls during work and to respond quickly in the event of an emergency. Especially, when using the flame-retardant sheet | seat of this invention for a partition etc., it is more preferable that this haze value is 20% or less.

  Although the thickness of a base film is not specifically limited, It is preferable that it is 10-500 micrometers, It is more preferable that it is 15-200 micrometers, It is most preferable that it is 50-100 micrometers. When the thickness of the base film is 10 μm or more, a flame retardant sheet excellent in tear strength can be obtained, and on the other hand, when it is 500 μm or less, flame retardant excellent in flexibility that does not break when bent. A sheet can be obtained.

The basis weight of the base film is not particularly limited, but is preferably 5 to 500 g / m ² and more preferably 10 to 100 g / m ² from the viewpoint of tear strength and flexibility.

  As the base film, other polymers may be alloyed or blended as long as the effects of the present invention are not impaired, and a laminated film may be used. Various additives such as a slip agent, a weather resistance assistant, and an antistatic agent may be added in order to improve ease of handling, durability, and processability.

  The flame retardant layer contains a flame retardant. As the flame retardant, an organic flame retardant or an inorganic flame retardant can be used, and examples thereof include a foaming flame retardant, a nitrogen flame retardant, a phosphorus flame retardant, and a sulfur flame retardant. These may be used alone or in combination of two or more. Among these, from the viewpoint of reducing the ash content after incineration, the flame retardant is preferably an organic flame retardant, and from the viewpoint of combustion gas safety, a foaming flame retardant such as hydrazodicarbonamide, melamine shear Nitrogen flame retardants such as nurate are preferred.

  The flame retardant is preferably not a halogen flame retardant. When halogenated flame retardants are used, halogenated gas is generated from the flame retardant sheet in the event of a fire or incineration, which adversely affects health and the environment. In addition, in order to avoid such adverse effects, do not incinerate. When disposed of in landfills, the amount of waste is greater than when incinerated. However, this does not apply when the amount of the halogen-based flame retardant is small. For example, when the ratio of the halogen flame retardant to the entire flame retardant sheet is 1% by mass or less, a halogen flame retardant may be used.

  The flame retardant layer further contains a synthetic resin binder. The synthetic resin binder plays a role of fixing the flame retardant to form a layer and a role of bonding the base film and the flame retardant layer. Examples of the synthetic resin binder include acrylic resins, urethane resins, polyester resins, polyamide resins, olefin resins, epoxy resins, and phenol resins. These may be used alone or in combination of two or more. Of these, urethane resins are particularly preferred from the viewpoint of relatively good flame retardancy.

  The concentration of the flame retardant in the flame retardant layer is preferably 5 to 99% by mass, more preferably 20 to 95% by mass, and most preferably 30 to 90% by mass. When the concentration is 5% by mass or more, the proportion of the synthetic resin binder is not excessively high and flame retardancy can be obtained efficiently. When the concentration is 99% by mass or less, the proportion of the synthetic resin binder is small. The adhesion between the base film and the flame retardant layer is good without becoming too much.

  The concentration of the synthetic resin binder in the flame retardant layer is preferably 1 to 95% by mass, more preferably 5 to 80% by mass, and most preferably 10 to 70% by mass. When the concentration is 1% by mass or more, the adhesiveness between the base film and the flame retardant layer is better, and when it is 95% by mass or less, the ratio of the flame retardant is not reduced too much and the flame retardancy is efficiently achieved. Can be obtained.

  The thickness of the flame retardant layer can be appropriately selected according to the thickness of the base film, and is preferably in the range of 0.5 to 10 times the thickness of the base film. A range of 8 times is more preferable, and a range of 2 to 5 times is most preferable. If the thickness of the flame retardant layer is less than the above range with respect to the thickness of the base film, it may not be possible to obtain sufficient flame retardancy. Wrinkles may occur during removal.

  The thickness of the flame retardant layer is preferably 10 to 500 μm, more preferably 20 to 300 μm, and most preferably 50 to 200 μm. If the thickness of the flame retardant layer is less than 10 μm, sufficient flame retardancy may not be obtained. On the other hand, if the thickness exceeds 500 μm, wrinkles may occur during winding.

  The flame retardant layer may contain a colorant such as an organic pigment or an inorganic pigment. In the present invention, the flame retardant layer may become white due to the influence of the flame retardant. As a result, the portion irradiated with strong light is blurred in white (that is, causes halation), and the transparency of the portion where the flame retardant layer is not present (that is, the visible light transmitting portion) may be impaired. In such a case, by adding a dark organic pigment or carbon black to the flame retardant layer to darken the flame retardant layer, it is possible to suppress halation and improve the transparency of the entire flame retardant sheet. it can.

  In addition to the above, the flame retardant layer may contain various additives such as an antioxidant, a weathering aid, and an antistatic agent, as long as the effects of the present invention are not impaired.

  The flame retardant layer is provided on both sides or one side of a base film having transparency. From the viewpoint of reducing the number of steps and reducing the production cost, it is preferably provided on one side, and from the viewpoint of obtaining a high level of flame retardancy, it is preferably provided on both sides. Moreover, when a flame retardant layer is provided on both sides, curling of the flame retardant sheet can be suppressed.

  When providing flame retardant layers on both sides, different flame retardant patterns, width dimensions, pitches, etc. may be adopted on each surface, or the same flame retardant pattern, width dimensions, pitches, etc. on each surface May be adopted. Also, after providing a flame retardant layer on one surface and then providing a flame retardant layer on both sides by a method of providing a flame retardant layer on the other surface, the flame retardant layer is located at the same position on each side (that is, from one side) When viewed, it may be difficult to provide the flame retardant layer on the other surface at a position hidden behind the flame retardant layer on one surface. In such a case, it is possible to improve the appearance by adopting a different flame retardant pattern, width dimension, pitch, and the like on each surface.

  The flame retardant layer is, for example, silk screen printing, rotary screen printing, gravure printing, using the flame retardant resin composition containing the above flame retardant, synthetic resin binder, and other components as necessary, as ink. The flame retardant layer can be provided on the base film by printing on the base film by a known and commonly used method such as letterpress printing, flexographic printing, and offset printing.

  The area ratio of the flame retardant layer on the base film is required to be 2 to 60%, preferably 5 to 40%, and more preferably 10 to 30%. When the area ratio of the flame retardant layer is less than 2%, there arises a problem that sufficient flame retardancy cannot be obtained. On the other hand, if it exceeds 60%, sufficient transparency cannot be obtained.

  In the flame retardant layer, the difference in the area ratio of the flame retardant layer to the area of the flame retardant sheet is preferably 20% or less, and preferably 10% or less, in any two locations of the flame retardant sheet. With such a configuration, it is possible to obtain a flame retardant sheet having flame resistance without unevenness over the entire surface. In addition, the area of two arbitrary places is selected as a 10 cm x 10 cm square size in the surface of a flame-retardant sheet | seat.

  The flame retardant layer may be regularly provided in the surface direction of the flame retardant sheet, may be provided randomly, or may be provided by constituting a character or a pattern. Especially, it is preferable that a flame retardant layer is provided regularly. With such a configuration, it is possible to obtain a flame retardant sheet having flame resistance without unevenness over the entire surface.

Adhesion amount of the substrate film of the flame retardant is preferably 1 to 40 g / ^{m 2,} and more preferably 2 to 20 g / ^{m 2.} If it exceeds 40 g / m ² , the flexibility of the flame retardant sheet may be hindered, and when the sheet is bent, the flame retardant layer may be peeled off from the base film, while 1 g / m ^2. If it is less than 1, sufficient flame retardancy may not be obtained.

  The mass ratio of the flame retardant to the entire flame retardant sheet is preferably 3 to 40% by mass, more preferably 5 to 35% by mass, and most preferably 10 to 30% by mass. More excellent flame retardancy can be obtained when the mass ratio of the flame retardant to the entire flame retardant sheet is 3% by mass or more. On the other hand, when the amount is 40% by mass or less, the amount of the flame retardant is not excessive and economical.

1-8 is an illustration of the handle of the flame retardant layer provided on the substrate film.
In FIG. 1, the flame retardant layer is provided on the base film in a lattice pattern. In FIG. 2, the flame retardant layer is provided in a large number of crosses in a vertical and horizontal arrangement on the base film. In FIG. 3, the flame retardant layer is provided on a substrate film in a number of staggered crosses. In FIG. 4, the flame retardant layers are provided so as to draw a large number of hexagons connected to each other. In FIG. 5, the flame retardant layer is provided on the base film so that the lattice pattern is slanted. In FIG. 6, the flame retardant layer is provided on the base film so as to form a large number of rhombus outlines. In FIG. 7, the flame retardant layer is provided on the base film so as to have a polka dot pattern. In FIG. 8, the flame retardant layer is provided on the base film so as to have a checkered pattern. In FIGS. 7 and 8, the black portions indicate the portions where the flame retardant layer is provided.

  The printed pattern by the flame retardant layer may be a continuous pattern or an independent pattern. As shown in FIG. 1, FIG. 4, and FIG. 5, the continuous pattern means a pattern in which the flame retardant layers are continuous (the flame retardant layers are connected to each other and are not independent). . The independent pattern means a pattern that is not connected to the flame retardant layer and is independent as shown in FIGS. 2, 3, 6, 7, and 8. Moreover, you may combine an independent pattern and a continuous pattern. In the present invention, it is preferable to use a continuous handle alone from the viewpoint that the fired flame is divided and is easy to extinguish. Especially, from the viewpoint of remarkably obtaining such an effect, as shown in FIG. 1 or FIG. A lattice pattern is more preferable.

  In the flame-retardant sheet | seat of this invention, the part in which the flame-resistant layer was provided in the base film surface, and the part in which the flame-resistant layer is not provided exist. Therefore, the thickness of both is different, that is, the portion where the flame retardant layer is provided is thicker than the portion where the flame retardant layer is not provided. Therefore, after obtaining the flame retardant sheet, when winding the flame retardant sheet, as the winding length of the roll increases, the portions where the flame retardant layer is provided, and the flame retardant layer are provided. Due to the overlapping of the portions that are not overlapped, there is a case where the size of the partial winding diameter is generated and the surface of the roll becomes uneven. As a result, the winding property is deteriorated, and wrinkles are likely to occur in a portion close to the core of the roll, and the transparency of the portion where the wrinkles are generated may be deteriorated.

  In order to reduce unevenness when winding up the flame retardant sheet, the portions where the flame retardant layer is provided and the portions where the flame retardant layer is not provided do not overlap as much as possible when winding the flame retardant sheet. It is preferable to provide a flame retardant layer on the base film with such a design. That is, it is preferable to provide the flame retardant layer so that the portion where the flame retardant layer is provided and the portion where the flame retardant layer is not provided overlap as much as possible when winding the flame retardant sheet. In such a case, since the above-mentioned unevenness is reduced, when the obtained flame-retardant sheet is wound up in a roll shape, the winding property is improved. Furthermore, since generation | occurrence | production of the wrinkle at the time of unwinding after unwinding the flame-retardant sheet which wound up is left, even if compared with immediately after providing a flame-resistant layer, a transparency does not fall and it is preferable. For example, when the flame retardant layer is provided on the base film with a pattern as shown in FIGS. 3 to 8, when the flame retardant sheet is wound, the portion provided with the flame retardant layer and the portion not provided are provided. It is most preferable because the unevenness is hardly expressed, the winding property is improved, and wrinkles are prevented from occurring when the wound flame-retardant sheet is left unrolled and then spread.

  As shown in FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5 and FIG. 6, when the flame retardant layer is provided by a combination of lines having a predetermined width dimension, the width dimension of the flame retardant layer is 0.5 to 20 mm is preferable, 1 to 10 mm is more preferable, and 1.5 to 8 mm is most preferable. If the width dimension of the flame retardant layer is 0.5 mm or more, it is excellent in the effect of suppressing the spread of fire and extinguishing the fire. Sex is not inhibited.

If it provided on the substrate film in a separate handle the flame retardant layer, the area of the flame retardant layer is preferably 1 to 1000 mm ^2, more preferably 3～500Mm ^2, is 20 to 200 mm ² Most preferred.

  When the flame retardant layer is provided on the base film with a polka dot pattern as shown in FIG. 7, the diameter of each polka dot pattern formed by the flame retardant layer is preferably 1 to 30 mm, and 2 to 20 mm. More preferably, it is most preferably 5 to 15 mm. When the diameter is 1 mm or more, it is excellent in the effect of suppressing fire spread and extinguishing the fire. On the other hand, when the diameter is 30 mm or less, even when the flame-retardant sheet is viewed from a short distance of 50 cm or less, the transmission visibility is hindered. Absent.

  The pitch of the flame retardant layer provided on the base film (the handle or the maximum gap between the lines forming the handle) is preferably 2 to 60 mm, more preferably 5 to 40 mm, and 8 to 30 mm. Is most preferred. If the pitch is less than 2 mm, the transparency may be lowered, and if it exceeds 60 mm, the flame retardancy may be lowered.

The total basis weight of the flame retardant sheet of the present invention comprising a base film and the flame retardant layer is preferably 10 to 500 g / ^{m 2,} and more preferably 20 to 300 g / ^{m 2.} If the total basis weight of the flame-retardant sheet is less than 10 g / m ² , the strength may be low, whereas if it exceeds 500 g / m ² , the amount of incineration at the time of disposal may increase.

  From the viewpoint of obtaining a sufficiently strong flame-retardant sheet, the tearing force of the flame-retardant sheet measured by JIS K7128-1 (trouser tear method) is preferably 0.05 N or more, and 0.1 N or more. More preferably. In addition, a preferable upper limit is 10 N or less.

  The flame-retardant sheet of the present invention may be laminated on one side or both sides of a material having transparency due to a gap between fibers, such as a fiber mesh (net). By laminating with a material such as a fiber mesh (net), the dimensional stability of the sheet is improved while maintaining transparency. In addition, the tear strength and tensile strength of the sheet are increased, durability can be improved and handling properties can be improved.

  The fiber used for the fiber mesh (net) is not particularly limited, and examples thereof include monofilament, multifilament, spun yarn, and slit yarn. Moreover, both natural fiber and synthetic fiber can be used. In addition, the fiber mesh (net) may be transparent or opaque, but when transparent, there is an advantage that the transparency of the flame-retardant sheet is not impaired.

  The fiber mesh may be subjected to known and usual processing such as dyeing, flame retardant processing, water repellent processing, and adhesive processing. In particular, by performing flame retardant processing that does not contain a halogen element on the fiber, the range in which the concentration, the printing line width, the printing pitch, etc. of the flame retardant layer provided on the base film can be appropriately changed can be expanded. It is effective for improving the flame retardancy and flame retardancy.

  When the flame-retardant sheet of the present invention is used as a construction or building sheet, it can achieve flame retardancy of V-2 level or higher in a flame-retardant test based on the UL-94 standard. preferable. Moreover, when used as a curing sheet for a nuclear power plant, it is preferable to achieve V-0.

  The term “curing sheet for a nuclear power plant” as used in the present invention refers to a radioactive material handling facility for radioactive materials, such as a nuclear power plant. It is a sheet for covering and protecting the device and its peripheral part in order to prevent contamination.

  The flame-retardant sheet of the present invention is suitably used for applications such as protective materials and building materials. In particular, since the flame-retardant sheet of the present invention is excellent in flame retardancy and transparency, it is suitably used as a curing sheet that is particularly useful for inspection, repair, and construction of nuclear power plants.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Measurement or evaluation method (1) Flame retardant evaluation When evaluated according to the thin material vertical combustion test method defined in the UL-94 standard and the sample conforms to VTM-0, VTM-1, VTM-2, These were designated as V-0, V-1, and V-2, respectively.
In the present invention, flame resistance of V-2 or higher is required to withstand the practical use for normal industrial use and architectural use. In order to be used as a curing sheet for a nuclear power plant, V-0 flame retardancy is required.

(2) Transmission visibility evaluation A test body was prepared by fixing a metal spanner having a maximum length of 20 cm on the surface of a commercially available white paper (size: width 30 cm x 30 cm, thickness 0.18 mm). The specimen was arranged vertically, and a place 2 m away from the specimen was taken as the visual position. Then, the sheet | seat obtained by the Example and the comparative example was arrange | positioned as a test piece (size: width 30cm x 30cm) between the visual position and the said test body. The specimen was visually observed through the specimen from the visual position while moving the position of the specimen from the visual position toward the specimen by 5 cm. When all the monitors were able to observe the presence of the spanner, the distance between the test piece and the specimen was measured and evaluated according to the following criteria. In this evaluation method, the monitor was placed in a state where only the test piece was not present, and was used for 10 persons who could observe the presence of the spanner.
(Circle): The distance of a test piece and a test body was 20 cm or more.
(Triangle | delta): The distance of a test piece and a test body was 10 cm or more and less than 20 cm.
X: The distance between the test piece and the test specimen was less than 10 cm.
In the present invention, it is assumed that a circle is one that can withstand practical use.

The raw materials used in the examples and comparative examples are shown below.
(1) Base film / nylon film having transparency (made by Unitika Ltd., thickness: 25 μm, haze value: 4.2%) (hereinafter sometimes referred to as “Ny25”)
6 nylon film (Unitika Ltd., thickness: 50 μm, haze: 8.6%) (hereinafter sometimes referred to as “Ny50”)
6 nylon film (Unitika Ltd., thickness: 15 μm, haze: 2.9%) (hereinafter sometimes referred to as “Ny15”)
Polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., thickness: 25 μm, haze: 1.3%) (hereinafter sometimes referred to as “PET”)

(2) Flame retardant / foamable flame retardant hydrazodicarbonamide (trade name “KBH-30” manufactured by Otsuka Chemical Co., Ltd.) (hereinafter sometimes referred to as “KBH-30”)
Nitrogen-based flame retardant melamine cyanurate (manufactured by Nissan Chemical Co., Ltd., trade name “MC-6000”) (hereinafter sometimes referred to as “MC-6000”)

(3) Synthetic resin binder / urethane resin (manufactured by DIC, trade name “Chrisbon 7367SL”) (solid content concentration: 35%) (hereinafter sometimes referred to as “7367SL”)

(Preparation of flame retardant resin composition forming a flame retardant layer)
A flame retardant resin composition (A-1) in which a synthetic resin binder 7367SL, a nitrogen-based flame retardant MC-6000 and a foamable flame retardant KBH-30 are mixed to form a flame retardant layer in the ratio shown in Table 1. To (A-8) were obtained.

  In Table 1, the composition of the flame retardant resin composition depends on the number of parts (parts by mass) of the nitrogen-based flame retardant MC-6000 and the foaming flame retardant KBH-30 with respect to 100 parts by mass of the solid content of the synthetic resin binder 7367SL. It is what is displayed. Table 1 shows the concentrations (mass%) of the flame retardants (KBH-30 and MC-6000) in (A-1) to (A-8).

Example 1
The flame retardant sheet of Example 1 was obtained by silk-screen printing (A-1) on one side of Ny25 (size: 30 cm × 30 cm) on a lattice pattern as shown in FIG. 1 with a width of 2 mm and a pitch of 25 mm. Obtained and evaluated. Table 2 shows the evaluation results of the obtained sheet.

(Example 2)
Except having used (A-2) instead of (A-1), it carried out similarly to Example 1, and obtained the flame-retardant sheet | seat of Example 2, and attached | subjected it to evaluation. Table 2 shows the evaluation results of the obtained sheet.
(Example 3)
A flame retardant sheet of Example 3 was obtained and evaluated in the same manner as Example 1 except that (A-3) was used instead of (A-1).
Example 4
Except having used (A-4) instead of (A-1), it carried out similarly to Example 1, and obtained the flame-retardant sheet | seat of Example 4, and attached | subjected it to evaluation.

(Example 5)
A flame retardant sheet of Example 5 was obtained and evaluated in the same manner as Example 1 except that (A-5) was used instead of (A-1).
(Example 6)
Except having used (A-6) instead of (A-1), it carried out similarly to Example 1, and obtained the flame-retardant sheet | seat of Example 6, and attached | subjected it to evaluation.
(Example 7)
A flame retardant sheet of Example 7 was obtained and evaluated in the same manner as Example 1 except that (A-7) was used instead of (A-1).

(Example 8)
The flame retardant sheet of Example 8 was obtained in the same manner as in Example 1 except that the pitch was changed to 15 mm and the flame retardant layer adhesion amount and flame retardant adhesion amount were changed as shown in Table 2. did.
Example 9
The flame retardant sheet of Example 9 was obtained in the same manner as in Example 2 except that the pitch was changed to 15 mm and the flame retardant layer adhesion amount and flame retardant adhesion amount were changed as shown in Table 2. did.
(Example 10)
The flame retardant sheet of Example 10 was obtained in the same manner as Example 3 except that the pitch was changed to 15 mm and the flame retardant layer adhesion amount and flame retardant adhesion amount were changed as shown in Table 2. did.

(Example 11)
A flame retardant sheet of Example 11 was obtained and evaluated in the same manner as Example 7 except that Ny50 was used instead of Ny25.
(Example 12)
A flame retardant sheet of Example 12 was obtained and evaluated in the same manner as in Example 1 except that Ny15 was used instead of Ny25, and the flame retardant layer adhesion amount and the flame retardant adhesion amount were changed as shown in Table 2. It was attached to.
(Example 13)
A flame retardant sheet of Example 12 was obtained and evaluated in the same manner as in Example 3 except that Ny15 was used instead of Ny25, and the flame retardant layer adhesion amount and the flame retardant adhesion amount were changed as shown in Table 2. It was attached to.

(Example 14)
Instead of the lattice pattern, a polka dot pattern (diameter 10 mm) as shown in FIG. 7 is printed at a pitch of 25 mm both vertically and horizontally, and the flame retardant layer adhesion amount and the flame retardant adhesion amount are changed as shown in Table 2, In the same manner as in Example 7, the flame-retardant sheet of Example 14 was obtained and evaluated.
(Example 15)
A cross pattern (width 2 mm) as shown in FIG. 2 was printed at a 25 mm pitch in place of the lattice pattern, and the flame retardant layer adhesion amount and flame retardant adhesion amount were changed as shown in Table 2. In the same manner as in Example 7, the flame-retardant sheet of Example 15 was obtained and subjected to evaluation.

(Example 16)
The flame retardant sheet of Example 16 was obtained in the same manner as in Example 7 except that Ny25 was replaced with a PET film and the flame retardant layer adhesion amount and the flame retardant adhesion amount were changed as shown in Table 2. It was attached.

  Table 2 shows the evaluation results of the flame-retardant sheets obtained in Examples 1 to 16.

(Comparative Example 1)
A sheet of Comparative Example 1 was obtained and evaluated in the same manner as in Example 1 except that a flame retardant layer was provided on the entire surface of Ny25 and the flame retardant layer adhesion amount and the flame retardant adhesion amount were changed as shown in Table 3. It was attached to.

(Comparative Example 2) to (Comparative Example 5)
The sheets of Comparative Examples 1 to 5 were obtained in the same manner as Comparative Example 1 except that the flame retardant layer adhesion amount and the flame retardant adhesion amount were changed as shown in Table 3, and subjected to evaluation.
(Comparative Example 6)
A sheet of Comparative Example 6 was obtained and evaluated in the same manner as Example 7 except that a flame retardant layer was provided on the entire surface of Ny25, and the flame retardant layer adhesion amount and the flame retardant adhesion amount were changed as shown in Table 3. It was attached to.

(Comparative Example 7) to (Comparative Example 9)
The sheets of Comparative Examples 7 to 9 were obtained in the same manner as Comparative Example 6 except that the flame retardant layer adhesion amount and the flame retardant adhesion amount were changed as shown in Table 3, and subjected to evaluation.
(Comparative Example 10)
A comparative example was carried out in the same manner as in Comparative Example 6 except that (A-8) was used instead of (A-7) and the flame retardant layer adhesion amount and the flame retardant adhesion amount were changed as shown in Table 3. Ten sheets were obtained and subjected to evaluation.
Table 3 shows the evaluation results of the flame-retardant sheets obtained in Comparative Examples 1 to 10.

(Comparative Example 11)
Ny25 used as a base film was used alone and evaluated as a sheet of Comparative Example 11. Table 3 shows the evaluation results of the sheet of Comparative Example 11.

As is clear from Table 2, the flame-retardant sheets of the present invention obtained in Examples 1 to 16 are excellent in transparency and flame retardancy, and the transparency of the flame-retardant layer can be changed even if the pattern is changed. Was maintained.
Further, since the sheets obtained in Examples 1 to 16 did not contain halogen, no harmful gas was generated after incineration, and almost no ash remained.

  The sheets of Comparative Examples 1 to 10 were inferior in transmission visibility because the flame retardant layer was provided on the entire surface of the base film.

  Although the sheet | seat of the comparative example 11 had favorable permeation | transmission visibility, it originated in not having the flame-resistant layer, and it burned down at the time of a flame-retardant evaluation, and was a sheet | seat without flame retardance.

Comparing Comparative Example 4 and Comparative Example 6, both flame retardant adhesion amounts are almost the same value (Comparative Example 4 is 7.2 g / m ² , Comparative Example 6 is 7.0 g / m ² ). In the flammability evaluation, Comparative Example 4 was at the V-2 level and Comparative Example 6 was at the V-0 level, and Comparative Example 6 was superior. The reason is that the flame retardant concentration of (A-7) used in Comparative Example 6 is higher than the flame retardant concentration of (A-1) used in Comparative Example 4, that is, a synthetic resin bond having flammability. It can be inferred that the concentration of the adhesive is low. That is, it was found that the flame retardancy is not due to only the amount of the flame retardant, but also due to the mass ratio of the flame retardant to the entire flame retardant sheet.

When Example 8 and Comparative Example 3 are compared, the amount of adhesion per unit area of both flame retardants is almost the same value (5.1 g / m ² in Example 8 and 5.6 g / m in Comparative Example 3). ² ) In the flame retardancy evaluation, Example 8 was at the V-0 level and Comparative Example 3 was at the V-2 level, and Example 8 was superior. From this result, it was found that, from the viewpoint of flame retardancy, it is advantageous to partially provide a flame retardant layer on the base film when the same amount of flame retardant per unit area is adhered. That is, the amount of the flame retardant used for imparting flame retardancy can be reduced, which is excellent in terms of cost.

Claims (4)

A flame retardant layer containing a flame retardant and a synthetic resin binder is provided by printing on one side or both sides of a base film having a haze of 40% or less measured according to JIS K7105, which does not contain a halogen element, A flame retardant sheet, wherein the area ratio of the flame retardant layer on the material film is 2 to 60 % .   The flame retardant sheet according to claim 1, wherein the flame retardant is at least one selected from a nitrogen flame retardant, a phosphorus flame retardant, and a sulfur flame retardant.   The flame retardant sheet according to claim 1 or 2, wherein a ratio of the flame retardant to the whole flame retardant sheet is 3 to 40% by mass.   A nuclear power plant curing sheet using the flame retardant sheet according to any one of claims 1 to 3.

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