JP2008168567A - Laminated sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated sheet capable of imparting flame retardancy to a foamed resin sheet, which is inexpensive, does not cause environmental pollution and does not accelerate degradation in the foamed resin sheet. <P>SOLUTION: A flame retardant oxide layer 3 which forms an oxide film when burned is laminated on at least one face of the resin foamed sheet 2, and laminating an endoergic layer 4 on the foamed resin sheet 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laminated plate, and more particularly, to a laminated plate suitable for a light reflecting plate used for the purpose of improving the luminance and illuminance of a light source device such as a lighting device, an electric signboard, and a backlight.

  Conventionally, laminates have been widely used in various industrial fields. As one type of such a laminated plate, there is one used as a light reflecting plate used for the purpose of improving the luminance and illuminance of a light source device such as a lighting device, an electric signboard, and a backlight.

  In the light source device, the light source is often arranged directly below the light extraction surface, and a light reflector is arranged directly below the light source for the purpose of effectively using light traveling in a direction opposite to the light extraction surface side of the light source. Is common.

  In such a light source device, the light reflector and the light source are very close to each other, and in order to ensure safety against fire, conventionally an aluminum panel or an aluminum panel with a white coating was used. In recent years, in order to meet demands for weight reduction and easy processing, a laminated plate in which a polyolefin resin foam sheet is laminated on at least one side of a metal plate has been proposed (for example, see Patent Document 1).

  By the way, in the laminated board which laminated | stacked the resin foam sheet on the at least single side | surface of the conventional metal plate, the flame retardance is calculated | required by the resin foam sheet in order to ensure the safety to a fire.

  For imparting flame retardancy to such a resin foam sheet, it is conceivable to add a flame retardant to the material forming the resin foam sheet.

JP 2004-167820 A

  However, imparting flame retardancy to a resin foam sheet by blending a flame retardant requires blending a large amount of a halogen-based flame retardant, for example, 10% by weight or more in order to ensure flame retardancy. There was a problem of becoming.

  In addition, imparting flame retardancy to resin foam sheets by blending halogen-based flame retardants has the problem that halogen compounds generate harmful dioxins by combustion, resulting in environmental pollution that affects animals and plants and the human body. It was.

  Furthermore, the halogen flame retardant has a problem that when the resin foam sheet is exposed to a high temperature and / or ultraviolet rays, it functions as a deterioration accelerator that promotes the deterioration of the resin.

  Therefore, there is a need for a high-quality laminate that can impart flame retardancy to a resin foam sheet at low cost without causing environmental pollution and without promoting deterioration.

  The present invention has been made in view of this point, and is a laminate that can impart flame retardancy to a resin foam sheet at low cost without causing environmental pollution and without promoting deterioration. The purpose is to provide a board.

  As a result of earnest research to achieve the above-mentioned object, the present inventors have laminated a flame retardant layer that forms an oxide film at the time of combustion on the surface of the resin foam sheet, so that oxygen to the resin foam sheet at the time of combustion is laminated. The present invention has been found to effectively block the supply of heat and to effectively function the oxide film by reducing the combustion temperature by diffusing combustion heat by laminating an endothermic layer on the resin foam sheet. It came to be completed.

  There are three flame retardant methods for resin foam sheets: extinguishing by generation of inert gas during combustion, blocking oxygen by forming an oxide film in the combustion layer during combustion, and suppressing combustion temperature by endothermic reaction such as dehydration reaction. It is roughly divided into methods.

  In the present invention, a flame retardant of the type that forms an oxide film is laminated on the surface layer of the resin foam sheet, thereby effectively forming an oxide film on the combustion site and suppressing the supply of oxygen to the combustion site.

  Here, in the formation of a thick flame retardant layer, the laminated plate used for the light reflection plate of the light source device such as a lighting device, an electric signboard, and a backlight needs to suppress the loss of light at the surface reflection portion. There is concern about adverse effects on optical properties. For this reason, it is necessary to suppress the thickness of the flame retardant layer to 10 μm or less. On the other hand, when the thickness of the resin foam sheet is 100 μm or more, a flame retardant layer having a thickness of 10 μm or less cannot form an oxide film sufficient to extinguish the flame, and the critical oxygen index, which is an index of flame retardancy, is reduced. I can hardly expect it.

  Therefore, the present invention suppresses the heat of combustion by applying an endothermic heat treatment to the surface of the resin foam sheet opposite to the combustion site, and has a sufficient extinguishing effect even when an oxide film having a thickness of 10 μm or less is formed. It is possible to get.

  Here, the endothermic heat treatment is more specifically realized by laminating an endothermic layer on the resin foam sheet.

  That is, the feature of the laminate of the present invention is that the resin foam sheet, the flame retardant layer that forms an oxide film at the time of combustion laminated on at least one surface of the resin foam sheet, and the resin foam sheet are laminated. It has an endothermic layer.

  In the present invention, it is preferable that the flame retardant layer is disposed on one surface of the resin foam sheet, and the endothermic layer is disposed on the other surface of the resin foam sheet.

  The resin foam sheet is preferably a thermoplastic resin sheet having fine bubbles or pores having an average cell diameter of not less than the wavelength of light and not more than 50 μm inside.

  The thermoplastic resin sheet is preferably a thermoplastic polyester foam having a thickness of 200 to 2000 μm, a specific gravity of 0.1 to 0.7, and a visible light diffuse reflectance of 90% or more.

  The endothermic layer is preferably a metal film having a thickness of 0.3 mm or less.

  According to the laminated board which concerns on this invention, a flame-resistant layer can interrupt | block the supply of oxygen to a resin foam sheet at the time of combustion efficiently. In addition, the endothermic layer can effectively function as a flame retardant layer by spreading the diffusion of combustion heat and lowering the combustion temperature. That is, effective flame retardancy can be imparted to the resin foam sheet by using a small amount of the flame retardant. As a result, the resin foam sheet has excellent effects such as being able to easily and reliably impart flame retardancy that does not cause environmental pollution and does not promote deterioration at low cost.

  The present invention will be described below with reference to embodiments shown in the drawings.

  FIG. 1 is a schematic cross-sectional view exaggerating and showing an essential part of the overall configuration of an embodiment of a laminated board according to the present invention.

  As shown in FIG. 1, the laminated board 1 of this embodiment has the flame-resistant layer 3 laminated | stacked on the upper surface which is one surface of the resin foam sheet 2 formed in flat form, and the heat absorption layer 4 on the lower surface which is the other surface. Are laminated.

  The material of the resin foam sheet 2 is not particularly limited, and examples thereof include a wide range of resins such as polyester, polycarbonate, polyamide, polyolefin, polystyrene, and acrylic. Among these, a polyester resin is particularly preferable in terms of foamability, heat resistance, and light reflectivity when used as a light reflection plate.

  The polyester resin is an aromatic dicarboxylic acid such as terephthalic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, Dicarboxylic acid units such as aliphatic dicarboxylic acids such as decanedicarboxylic acid and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylene glycol (propylene glycol), butanediol , Aliphatic glycols such as pentanediol, neopentyl glycol, hexamethylene glycol, dodecamethylene glycol, polyethylene glycol, cyclohexane dimethanol Alicyclic glycols, bisphenols such as a polyester resin formed from a diol units such as aromatic diols such as hydroquinones.

  Specific examples of these polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate, and polyethylene naphthalate. Of these, polyethylene terephthalate, which is easy to obtain an amorphous sheet and has excellent moldability and high crystallinity, is particularly suitable in terms of being lightweight and inexpensive.

  In addition, as the resin foam sheet 2 when the laminated plate 1 is used as a light reflecting plate, specifically, as an example of the resin film or sheet, an extruded sheet of thermoplastic polyester is impregnated with carbon dioxide under high pressure. Then, a polyester foam sheet (for example, MCPET (registered trademark) manufactured by Furukawa Electric Co., Ltd.) having an internal cell diameter of 50 μm or less can be used. In addition, a cyclopolyolefin foamed sheet having an internal cell diameter of 50 μm or less can also be used.

  Furthermore, as a method for manufacturing the resin foam sheet 2 when the laminated plate 1 is used as a light reflecting plate, it is preferable to use, for example, the following method in consideration of mass productivity.

  That is, a thermoplastic resin sheet is prepared, a roll is formed by winding the thermoplastic resin sheet and a separator, and the roll is held in a pressurized inert gas atmosphere to be inert to the thermoplastic resin sheet. In this method, a thermoplastic resin sheet containing a gas and further containing an inert gas is heated to a temperature equal to or higher than the softening temperature of the thermoplastic resin under normal pressure to be foamed.

  Examples of the inert gas include helium, nitrogen, carbon dioxide, and argon. The permeation time of the inert gas and the permeation amount of the inert gas until the thermoplastic resin sheet is saturated vary depending on the type of resin to be foamed, the type of inert gas, the permeation pressure, and the thickness of the sheet. Carbon dioxide is more preferable in consideration of gas permeability to the resin, gas penetration rate, gas solubility, and the like.

  In addition, in the method of manufacturing such a resin foam sheet 2, before the roll which consists of a resin sheet and a separator is hold | maintained in a pressurized inert gas atmosphere and an inert gas is contained in a thermoplastic resin sheet, it is. It may be contained in an organic solvent.

  Examples of the organic solvent include benzene, toluene, methyl ethyl ketone, ethyl formate, acetone, acetic acid, dioxane, m-cresol, aniline, acrylonitrile, dimethyl phthalate, nitroethane, nitromethane, and benzyl alcohol. Among these, acetone is more preferable from the viewpoints of handleability and economy.

  In addition, as the resin foam sheet 2 in the case where the laminated plate 1 is used as a light reflecting plate, a film or sheet of a thermoplastic resin containing a filler, in which a large number of voids are formed with the filler as a core, or Sheet. In this case, in the film or sheet, the thermoplastic resin film or sheet containing the filler is formed by forming an unstretched film or sheet containing the filler and stretching the unstretched film or sheet. A porous stretched film or sheet in which a large number of voids are formed as nuclei is preferable.

  When used as a light reflecting plate, the thickness of the resin foam sheet 2 is preferably 200 to 2000 μm. If the thickness of the resin foam sheet 2 is in the range of 200 to 2000 μm, the resin foam sheet 2 is rigid and there is little leakage of light to the back surface of the light reflecting plate.

  The specific gravity of the resin foam sheet 2 when used as a light reflecting plate is preferably 0.1 to 0.7. If the specific gravity of the resin foam sheet 2 exceeds 0.7, even if other requirements are satisfied, light leakage to the back surface of the light reflecting plate increases due to the transparency of the resin foam sheet 2 so that light loss increases. .

  When the resin foam sheet 2 is used as a light reflecting plate, the visible light reflectance is preferably 90% or more. When the visible light reflectance of the resin foam sheet 2 is 90% or more, the irregular reflection effect of light from the light source is enhanced. The diffuse reflectance of visible light in this specification refers to the ratio of the diffuse reflectance flux to the incident light flux, measured at a wavelength of 550 nm with a self-recording spectrophotometer, and diffused on a white plate in which fine powder of barium sulfate is hardened. This is a value obtained as a relative value with a reflectance of 100%. As the self-recording spectrophotometer, for example, UV-3100PC (trade name, manufactured by Shimadzu Corporation) can be used.

  The bubble diameter (average bubble system) contained in the resin foam sheet 2 when used as a light reflecting plate is not particularly limited, but is not less than the wavelength of light and not more than 50 μm, more preferably 0.01. ˜20 μm, most preferably 0.01 to 10 μm. If the bubble diameter is smaller than 0.01 μm, it becomes too small compared to the wavelength of visible light, so that light is easily transmitted and the characteristics as a light reflecting plate are inferior. On the other hand, if the bubble diameter exceeds 20 μm, the reflectance of the entire light reflecting plate is inferior, and as a result, the characteristics as a light reflecting plate are insufficient.

  The resin used as the material of the resin foam sheet 2 when used as a light reflecting plate includes a crystallization nucleating agent, a crystallization accelerator, an aerated nucleating agent, an antioxidant, a charge, as long as the properties are not affected. Various additives such as inhibitors, UV inhibitors, light stabilizers, optical brighteners, compatibilizers, lubricants, reinforcing agents, flame retardants, crosslinking agents, crosslinking aids, plasticizers, thickeners, thickeners May be blended.

  Ultraviolet absorbers and light stabilizers are organic light stabilizers such as hindered amines, salicylic acids, benzophenones, benzotriazoles, cyanoacrylates, triazines, benzoates, oxalic anilides, sol gels and metal oxides. An inorganic light stabilizer such as a product can be used. However, since the organic ultraviolet absorber is yellowish when the amount is large, it is preferably 0.01 to 1% by weight. The inorganic ultraviolet absorber is not limited thereto, but is preferably 0.01 to 10% by weight in view of other characteristics such as strength of the foam.

  In addition, the resin layer containing the said additive may be laminated | stacked on the surface of the resin foam sheet 2, and the coating layer containing the said additive may be provided. Among them, it is preferable to use a layer containing an ultraviolet absorber because a sufficient ultraviolet deterioration resistance can be provided even when a resin that easily causes ultraviolet deterioration is used for the light reflecting plate.

  In addition, one type of resin may be used alone, or two or more types may be mixed and used.

  The flame retardant layer 3 is characterized by the formation of an oxide film during combustion, but the material is not particularly limited. However, it is particularly preferable to use a condensed phosphate ester as a flame retardant from the viewpoint of flame retardancy. This flame retardant may be dissolved in a solvent and applied to the surface of the resin foam sheet 2, or a resin containing a flame retardant may be laminated on the surface of the resin foam sheet 2.

  The endothermic layer 4 is intended to absorb and diffuse the combustion heat, and does not specifically limit the substance. However, metals, particularly aluminum, are most preferred from the viewpoints of heat capacity, thermal conductivity, and scientific stability.

  The endothermic layer 4 is intended to absorb and diffuse combustion heat. Therefore, there is a high possibility that the same effect can be realized even by adding a material that can realize such an application, that is, a flame retardant that promotes an endothermic reaction during combustion.

  Although the lamination | stacking method of the flame-resistant layer 3 with respect to the said resin foam sheet 2 is not specifically limited, Coating (coating) of the flame-resistant layer 3 is common. Moreover, although the lamination | stacking method of the heat absorption layer 3 with respect to the resin foam sheet 2 is not specifically limited, Pasting with a double-sided tape, an adhesive agent, etc. is common.

  Hereinafter, the present invention will be described specifically by way of examples. In addition, this invention is not limited by this.

(Example 1)
Coating the coating by blending 5% by weight of a condensed phosphate ester in an acrylic binder to the surface of the resin foam sheet 2 (MCPET manufactured by Furukawa Electric Co., Ltd .: thickness 0.8 mm) The flame retardant layer 3 was laminated. The coating thickness of the flame retardant layer 3 was in the range of 2.5 ± 0.5 μm. Thereafter, an aluminum plate having a thickness of 0.1 mm is bonded to the back surface of the resin foam sheet 2 by using a double-sided tape (manufactured by Kyori Giken Kagaku Co., Ltd.) using an acrylic adhesive, and the endothermic layer 4 is laminated. A laminated plate 1 was obtained.

(Comparative Example 1)
The flame retardant layer 3 was laminated on the surface of the resin foam sheet 2 without forming the endothermic layer 4 of the laminate 1 of Example 1.

(Comparative Example 2)
The flame retardant layer 3 was laminated on both the front and back surfaces of the resin foam sheet 2 without forming the endothermic layer 4 of the laminate 1 of Example 1.

(Comparative Example 3)
The endothermic layer 4 was laminated on the back surface of the resin foam sheet 2 without forming the flame retardant layer 3 of the laminate 1 of Example 1.

(Comparative Example 4)
Only the resin foam sheet 2 was formed without forming the flame retardant layer 3 and the endothermic layer 4 of the laminate 1 of Example 1.

  Next, each of Example 1 and Comparative Examples 1 to 4 was evaluated for flame retardancy.

  In addition, flame retardance is evaluated mainly by measuring the critical oxygen index. Further, the horizontal burning rate was measured according to MVSS (Motor Vehicles Safety Standard).

  The limiting oxygen index was measured by the A method (upper surface ignition method) in accordance with JIS K 7201-1, and JIS K 72021-2. The test piece was No. III.

  The MVSS was measured as a horizontal burning rate in accordance with MVSS302 and JIS D1201. The sample was adjusted under the conditions of 20 ± 5 degrees and humidity of 50 ± 5%, and a combustion test using city gas was performed.

  The laminated board of Example 1 had a critical oxygen index of 24.5, and ignition could not be confirmed in the horizontal combustion test.

  On the other hand, the laminated board of Comparative Example 1 had a critical oxygen index of 19.5 and a burning rate of 130 mm / sec.

  Further, the laminated plate of Comparative Example 2 had a limiting oxygen index of 20.0 and a burning rate of 60 mm / sec.

  The laminated plate of Comparative Example 3 had a limiting oxygen index of 20.0 and a combustion rate of 90 mm / sec.

  The laminated plate of Comparative Example 4 had a limiting oxygen index of 19.0 and a combustion rate of 160 mm / sec.

  As is clear from the above evaluation results, in Example 1, the limiting oxygen index is high and does not burn, whereas in Comparative Examples 1 to 4, the limiting oxygen index is low, and it can ignite and burn. found.

  Therefore, according to the laminated board of Example 1, it is easy and sure to provide the resin foam sheet with flame retardancy that does not cause environmental pollution and does not promote deterioration at low cost. it can.

  The laminate of the present invention is not only a light reflector used for the purpose of improving the brightness and illuminance of a light source device such as a lighting device, an electric signboard, and a backlight, but also a panel for building materials, an exterior material for electrical appliances, and an interior for automatic use. It can be used for various applications such as materials.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible as needed.

Schematic sectional view exaggeratingly showing the main part of the overall configuration of an embodiment of a laminated board according to the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laminated board 2 Resin foam sheet 3 Flame retardant layer 4 Endothermic layer

Claims (5)

  It has a resin foam sheet, a flame retardant layer which is laminated on at least one surface of the resin foam sheet and forms an oxide film at the time of combustion, and an endothermic layer laminated on the resin foam sheet. Laminated board.   The laminate according to claim 1, wherein the flame retardant layer is disposed on one surface of the resin foam sheet, and the heat absorbing layer is disposed on the other surface of the resin foam sheet.   3. The laminate according to claim 1, wherein the resin foam sheet is a thermoplastic resin sheet having fine bubbles or pores having a bubble diameter of not less than the wavelength of light and not more than 50 μm.   The thermoplastic resin sheet is a thermoplastic polyester foam having a thickness of 200 to 2000 µm, a specific gravity of 0.1 to 0.7, and a visible light diffuse reflectance of 90% or more. Item 4. The laminated sheet according to item 3.   The laminated plate according to any one of claims 1 to 4, wherein the endothermic layer is a metal film having a thickness of 0.3 mm or less.

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