JP2009083150A - Flame retardant sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame retardant sheet for restricted combustion with combustible gas generated by thermal decomposition of a base sheet starting from cracking in a side surface of the base sheet or a flame retardant treatment layer produced by carrying out flame retardant treatment to surfaces of the base sheet. <P>SOLUTION: The flame retardant sheet comprises a flame retardant treatment layer on both surfaces of the base sheet, comprising resin components of phosphorus-containing polyester resin containing specific phosphorus-containing compound, acrylic polyol resin and isocyanate hardening agent of a glass transition temperature of 60°C or over, magnesium hydrate of average grain size of 0.01 μm-1 μm, and montmorillonite. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flame retardant sheet in which a surface of a substrate sheet is subjected to a flame retardant treatment, and particularly relates to a flame retardant sheet that prevents combustion from a side surface of the substrate sheet.

  With the improvement of social safety awareness and the construction of advanced social infrastructure such as high-rise buildings and high-speed railways, more diverse safety is required in the materials field.For example, indoor wallpaper and smoke shielding in high-rise buildings Sheets used on screens, underpass signboard surfaces, smoke barriers, etc. are required to have flame-retardant performance in order to prevent fire.

  Conventionally, as such a flame retardant sheet, a sheet obtained by blending various flame retardants with a resin having low flammability has been proposed.

  For example, a flame retardant sheet obtained by processing a flame retardant resin obtained by adding melamine cyanurate to a polyamide resin into a sheet shape has been proposed (Patent Document 1). However, such a flame retardant sheet has flexibility and strength. Low and insufficient physical properties.

  In addition, for example, a flame retardant sheet in which a large amount of an inorganic flame retardant such as aluminum hydroxide or magnesium hydroxide is blended with an olefin resin and processed into a sheet shape has been proposed. Since a large amount of an inorganic flame retardant is blended, the transparency is low, so that it cannot be used in a colorless and transparent application, and there is a problem that the application is limited. There is also a problem that the toughness of the sheet is lowered.

  In addition, for example, a flame retardant sheet in which a halogen-based flame retardant is blended with an olefin resin and processed into a sheet shape has been proposed, but halogen gas is generated during incineration, and it has been pointed out that the equipment is corroded and affects the human body. Furthermore, there is a problem of environmental pollution such as generation of dioxins.

Japanese Patent Laid-Open No. 2001-31780

  Therefore, the present inventors have a low combustibility film (such as an inorganic film such as silica or a flame retardant resin such as a silicone resin) on the surface of a flexible and strong base sheet having good workability. By providing a flame retardant treatment layer), the surface of the base sheet is subjected to a flame retardant treatment to produce a flame retardant sheet. The surface of the base sheet is made flame retardant by the flame retardant treatment layer. However, when the side surface of the base sheet was exposed to fire, the base sheet was thermally decomposed to generate a combustible gas and started to burn. In addition, since the base sheet is easily stretched by heat and the flame retardant treatment layer is easily contracted by heat, the flame retardant treatment layer can follow the base sheet that is thermally deformed when exposed to fire. However, the flame-retardant treatment layer was cracked, and a phenomenon occurred in which the combustible gas generated by pyrolysis from the base sheet portion exposed from the crack was ignited and burned.

  Therefore, the present invention provides a flame retardant treatment on the surface of the base sheet, whereby the base sheet is thermally decomposed from a crack of the side face of the base sheet or the flame retardant layer, and is burned by a combustible gas. It aims at providing the flame-retardant sheet | seat which suppressed this.

  The flame-retardant sheet of the present invention comprises a resin component comprising a phosphorus-containing polyester resin, an isocyanate-curable resin having a glass transition temperature of 60 ° C. or higher, and an isocyanate-based curing agent, an inorganic flame retardant, and layered silicic acid on both sides of the base sheet. It has a flame-retarded layer made of salt.

  The flame-retardant sheet of the present invention is characterized in that the layered silicate is smectite.

  The flame retardant sheet of the present invention is characterized in that the smectite is montmorillonite.

  In the flame-retardant sheet of the present invention, the content of the layered silicate is 5 to 15 parts by weight with respect to 100 parts by weight of the resin component excluding the isocyanate curing agent. It is.

（式中、Ｒ¹〜Ｒ⁸はそれぞれ水素原子又は有機基を示し、それぞれ同一であっても、異なるものであってもよい。また、Ａは水素原子又は有機基を示し、Ｒ¹〜Ｒ⁸と同一であっても、異なっていてもよい。但し、Ｒ¹〜Ｒ⁸並びにＡのうちの少なくとも一つはエステル形成性官能基を有する。） The flame-retardant sheet of the present invention is characterized in that the phosphorus-containing polyester resin contains a phosphorus-containing compound represented by the following general formula (I).

(In the formula, R ^{1 to} R ⁸ each represents a hydrogen atom or an organic group, and may be the same or different. A represents a hydrogen atom or an organic group, and R ^{1 to} R ⁸ may be the same as or may be different. However, at least one of R ¹ to R ⁸ and a is an ester-forming functional group.)

  In the flame-retardant sheet of the present invention, the isocyanate curable resin is an acrylic polyol resin.

  In the flame-retardant sheet of the present invention, the ratio of the phosphorus-containing polyester resin and the isocyanate-curable resin in the flame-retardant treatment layer is 6: 4 to 8: 2 by weight. Is.

  The flame retardant sheet of the present invention is characterized in that the inorganic flame retardant is magnesium hydroxide.

  In the flame-retardant sheet of the present invention, the content of the magnesium hydroxide in the flame-retardant treatment layer is 50 to 90 parts by weight with respect to 100 parts by weight of the resin component excluding the isocyanate curing agent. It is characterized by being.

  The flame-retardant sheet of the present invention is characterized in that the magnesium hydroxide has an average particle diameter of 0.01 μm to 1 μm.

  According to the present invention, the surface of the base sheet is subjected to a flame retardant treatment, so that the base sheet is thermally decomposed from a crack of the side surface of the base sheet or the flame retardant layer, and is combusted by a combustible gas. The flame-retardant sheet | seat which suppressed is obtained.

  Hereinafter, embodiments of each component will be described.

  The substrate sheet of the present invention may be appropriately selected depending on the use regardless of whether it is transparent or opaque, but the material may be polyester, polyvinyl chloride, polycarbonate, polypropylene, polyethylene as long as it is transparent. And plastic films such as acrylic and acetylcellulose, plastic sheets, plastic plates, and the like. Opaque materials include opaque substrates such as paper and synthetic paper, the above plastic films, those made opaque by adding pigments inside the sheets and plates, and the above plastic films, sheets and plates The thing provided with the colored layer which has concealment property etc. is mention | raise | lifted.

  The thickness of the base sheet varies depending on the use and cannot be generally specified. However, in consideration of ease of handling, the thickness of the base sheet is 2 μm or more, preferably 10 μm or more, preferably 300 μm or less if it is a film or sheet. In the following, it is generally considered to be 125 μm or less, and in the case of a plate shape, 10 mm or less, preferably 3 mm or less.

  Such a base sheet is subjected to easy adhesion treatment such as plasma treatment, corona discharge treatment, deep ultraviolet irradiation treatment, or undercoat easy adhesion treatment in order to improve the adhesion to the flame retardant treatment layer described later. A layer may be provided. Moreover, such a base material sheet may contain various commonly used ultraviolet absorbers, antioxidants, etc., or may have a layer containing these separately. Moreover, such a base material sheet may be provided with a printed pattern layer such as indoor wallpaper or printed matter for advertisement.

  Next, the flame retardant treatment layer will be described. The flame retardant treatment layer is composed of a phosphorus-containing polyester resin, a resin component comprising an isocyanate curable resin having a glass transition temperature of 60 ° C. or higher and an isocyanate curing agent, an inorganic flame retardant, and a layered silicate.

  By having a phosphorus-containing polyester resin and an isocyanate curable resin having an glass transition temperature of 60 ° C. or higher and an isocyanate curing agent as the resin component, the resin component itself is prevented from burning, and the resin component expands by heat. By covering the side surface of the base sheet and making it difficult to cause cracks in the flame retardant treatment layer, and by using an inorganic flame retardant and layered silicate in such a resin component, A carbonized layer can be formed and combustion by combustible gas generated from a substrate sheet can be suppressed.

  Such a phosphorus-containing polyester resin is used for suppressing the combustion of the resin component of the flame retardant layer because the resin itself is difficult to burn. Moreover, the side surface of a base material sheet can be covered by using with the isocyanate curable resin mentioned later, and the combustion from a base material sheet side surface can be suppressed. In addition, since the phosphorus-containing polyester resin is excellent in flexibility, the followability to the base sheet softened by heat can be improved, so that it is difficult to cause cracks in the flame-retardant treatment layer. .

  The phosphorus-containing polyester resin is obtained by subjecting a dicarboxylic acid component, a glycol component, and a phosphorus-containing compound to a condensation reaction or a polycondensation reaction.

  As said dicarboxylic acid component, dicarboxylic acids, such as aromatic dicarboxylic acid and aliphatic dicarboxylic acid, can be mentioned, for example. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, diphenic acid, naphthalic acid, 1,2-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,6. -Alkali metal salts such as 5-sulfoisophthalic acid, 2-sulfoisophthalic acid, 4-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfonaphthalene-2,6-dicarboxylic acid, etc. Examples of the aliphatic dicarboxylic acid include linear, branched and alicyclic oxalic acid, malonic acid, succinic acid, maleic acid, itaconic acid, glutaric acid, adipic acid, pimelic acid, 2,2-dimethylglutaric acid, and suberin. Acid, azelaic acid, sebacic acid, dodecanedioic acid, 1,3-cyclopentanedicarboxylic acid, 1 4-cyclohexanedicarboxylic acid, diglycolic acid, can be given thiodipropionic acid.

  In addition to dicarboxylic acids as described above, dicarboxylic acid components are derivatives of dicarboxylic acids such as anhydrides, esters, acid chlorides, halides, etc. It also includes those that form (ester-forming derivatives of dicarboxylic acids).

  Among these, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedioic acid are easy to react. From the viewpoint of weather resistance, durability and the like of the resin to be obtained. In particular, it is optimal to use only aromatic dicarboxylic acids or to have aromatic dicarboxylic acids as a main component.

  Examples of the glycol component include ethylene glycol and diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, heptaethylene glycol, octaethylene glycol, and other polyethylene glycols, as well as propylene glycol and dipropylene glycol, triethylene glycol, and the like. Polypropylene glycol such as propylene glycol and tetrapropylene glycol, and 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2 -Dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propane All, 2,2,4-trimethyl-1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetra Methyl-1,3-cyclobutanediol, 4,4′-dihydroxybiphenol, 4,4′-methylenediphenol, 4,4′-isopropylidenediphenol, 1,5-dihydroxynaphthalene, 2,5-dihydroxynaphthalene, Examples include 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), bisphenol S, bisphenol A, and the like.

  In addition to the glycols as described above, the glycol component is a derivative of glycol, such as a diacetate compound corresponding to these glycols, which reacts with the dicarboxylic acid component to form an ester (glycol Ester-forming derivatives).

  These glycol components can be used alone or in combination of two or more. Among these, ethylene glycol, diethylene glycol, butanediols such as 1,4-butanediol, hexanediols such as 1,6-hexanediol, 1,4-cyclohexanedimethanols, neopentyl glycol and bisphenol A and the like are preferable from the viewpoints of easy reaction, durability of the obtained resin, and the like.

  Moreover, in order to provide the reactivity with the phosphorus containing epoxy resin mentioned later to such a phosphorus containing polyester resin, as a reactivity provision component, for example, tribasic acid anhydride, tetrabasic acid anhydride, etc. more than trivalent It is preferable to use a polyvalent carboxylic acid component or the like. In this case, the reaction can be terminated with the carboxyl group resulting from the polyvalent carboxylic acid remaining in the skeleton, and the remaining carboxyl group can be used as the reactive group.

  Examples of the trivalent or higher polyvalent carboxylic acid component include hemimellitic acid, trimellitic acid, trimedic acid, merophanic acid, pyromellitic acid, benzenepentacarboxylic acid, meritic acid, and cyclopropane-1,2,3-tricarboxylic acid. , Cyclopentane-1,2,3,4-tetracarboxylic acid, ethanetetracarboxylic acid, (5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid, etc. And carboxylic acid derivatives such as anhydrides, esters, acid chlorides, halides, etc., which are derivatives of polycarboxylic acids that react with glycol components to form esters (polyvalent carboxylic acids). Ester-forming derivatives). Of these, trimellitic anhydride and pyromellitic anhydride are particularly preferably used from the viewpoint of preventing three-dimensional crosslinking of the phosphorus-containing polyester resin as much as possible and effectively leaving the carboxyl group even after the polycondensation reaction. The reactivity imparting components as described above may be used alone or in combination of two or more.

  Moreover, it is preferable that the usage-amount of a reactivity provision component shall be 1-60 mol% in the total amount of the said dicarboxylic acid component and a reactivity provision component, and can eliminate the unnecessary crosslinking reaction in a manufacturing process in this case. Under the polymerization conditions, a sufficient degree of polymerization can be obtained, and a sufficient reactive group can be imparted to the phosphorus-containing polyester resin.

  Next, as the phosphorus-containing compound, a compound that can be condensed or polycondensed by reacting with at least one of the dicarboxylic acid component, the glycol component, and the reactivity-imparting component is used. Specifically, an ester is formed in the molecule. It is preferable to use those having a functional functional group.

  The above ester-forming functional group means a functional group that reacts with another carboxyl group or hydroxyl group to form an ester bond. In addition to the carboxyl group and the hydroxyl group, the carboxyl group is made anhydride, ester Derived from acidification, acid chlorideation, halogenation, etc., which reacts with other hydroxyl groups to form ester bonds (carboxyl ester-forming derivatives), and hydroxyl groups to acetate And those that are derived by reacting with other carboxyl groups to form ester bonds (ester-forming derivatives of hydroxyl groups).

  In particular, when the ester-forming functional group is a carboxyl group or a hydroxyl group, it is preferable because good reactivity can be obtained in the production process.

  In particular, it is preferable that the phosphorus-containing compound has one or two ester-forming functional groups in one molecule. In such a case, unnecessary crosslinking is performed in the production process of the phosphorus-containing polyester resin. Even when the polymerization conditions are adjusted so as to eliminate the reaction, a phosphorus-containing polyester resin having a sufficient degree of polymerization can be obtained. Further, when the phosphorus-containing compound has two ester-forming functional groups, better results can be obtained when both of the two ester-forming functional groups are carboxyl groups or hydroxyl groups.

  As the above phosphorus-containing compounds, the compounds represented by the following general formulas (I) to (III) can be exemplified as preferable ones because they are particularly excellent in the ease of reaction, flame retardancy and the like. Compounds represented by formula (I) are optimal.

（式中、Ｒ¹〜Ｒ⁸はそれぞれ水素原子又は有機基を示し、それぞれ同一であっても、異なるものであってもよい。また、Ａは水素原子又は有機基を示し、Ｒ¹〜Ｒ⁸と同一であっても、異なっていてもよい。但し、Ｒ¹〜Ｒ⁸並びにＡのうちの少なくとも一つはエステル形成性官能基を有する。）

(In the formula, R ^{1 to} R ⁸ each represents a hydrogen atom or an organic group, and may be the same or different. A represents a hydrogen atom or an organic group, and R ^{1 to} R ⁸ may be the same as or may be different. However, at least one of R ¹ to R ⁸ and a is an ester-forming functional group.)

（式中、Ｒ⁹及びＲ¹⁰はそれぞれ水素原子又は有機基を示し、それぞれ同一であっても、異なるものであってもよい。ただし、Ｒ⁹及びＲ¹⁰の少なくとも一方はエステル形成性官能基を有する。）

(Wherein R ⁹ and R ¹⁰ each represent a hydrogen atom or an organic group and may be the same or different, provided that at least one of R ⁹ and R ¹⁰ is an ester-forming functional group. Have

（式中、Ｒ¹¹〜Ｒ¹³はそれぞれ水素原子又は有機基を示し、それぞれ同一であっても、異なるものであってもよい。ただし、Ｒ¹¹〜Ｒ¹³の少なくともいずれかはエステル形成性官能基を有する。）

(In the formula, R ^{11 to} R ¹³ each represent a hydrogen atom or an organic group, and may be the same or different. However, at least one of R ^{11 to} R ¹³ is an ester-forming functional group. Group.)

  As the phosphorus-containing compounds represented by the general formulas (I) to (III), those having one or two ester-forming functional groups in one molecule are particularly preferable.

  Here, the organic group in the general formulas (I) to (III) is an appropriate substituent, and is not particularly limited, but a monovalent organic group having 1 to 1000 carbon atoms is preferable. Examples of monovalent organic groups include aliphatic hydrocarbon groups such as alkyl groups and alkenyl groups, alicyclic hydrocarbon groups such as cyclohexyl groups, aromatic hydrocarbon groups such as aryl groups, and hydrocarbon groups such as aralkyl groups. And a carboxyl group, an alkyloxy group, and the like. These groups may further contain a functional group. For example, it may have a substituent containing an ester-forming functional group (carboxyl group, hydroxyl group, and ester-forming derivative group derived therefrom). However, as described above, the number of ester-forming functional groups present in one molecule is preferably 1 or 2.

The phosphorus-containing compound represented by the general formula (I) preferably has one or two ester-forming functional groups, and these are desirably present in A which is an organic group. Among the phosphorus-containing compounds represented by the above general formula (I), particularly preferred are R ^{1 to} R ⁸ are hydrogen atoms, and A is a hydroxyl group, a carboxyl group or these as an ester-forming functional group. In this case, the reactivity of the phosphorus-containing polyester resin is improved, and the reaction of the resulting phosphorus-containing polyester resin Property, flame retardancy, heat resistance and the like can be particularly improved.

  Examples of the phosphorus-containing compound represented by the general formula (I) include those represented by the following chemical formulas (a) to (e).

（式中、Ｒ¹⁴は水素原子又は炭素数１〜６の、直鎖状若しくは分岐を有するアルキル基又は脂環基を示す。）

(In the formula, R ¹⁴ represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or an alicyclic group.)

（式中、Ｒ¹⁵及びＲ¹⁶は、それぞれ水素原子、又は炭素数１〜６の直鎖状若しくは分岐を有するアルキル基又は脂環基を示し、Ｒ¹⁵及びＲ¹⁶は同一のものでも異なるものでもよい。）

(Wherein R ¹⁵ and R ¹⁶ each represent a hydrogen atom, or a linear or branched alkyl group having 1 to 6 carbon atoms or an alicyclic group, and R ¹⁵ and R ¹⁶ are the same or different. May be.)

  Among the phosphorus-containing compounds represented by the above general formula (II), particularly preferred are those represented by the following chemical formulas (f) and (g).

（式中、Ｒ¹⁷は水素原子、又は炭素数１〜６の直鎖状若しくは分岐を有するアルキル基又は脂環基を示す。）

(In the formula, R ¹⁷ represents a hydrogen atom, or a linear or branched alkyl group or alicyclic group having 1 to 6 carbon atoms.)

（式中、Ｒ¹⁸は水素原子、又は炭素数１〜６の直鎖状若しくは分岐を有するアルキル基又は脂環基を示す。）

(In the formula, R ¹⁸ represents a hydrogen atom, or a linear or branched alkyl group or alicyclic group having 1 to 6 carbon atoms.)

  Among the phosphorus-containing compounds represented by the general formula (III), particularly preferred are those represented by the following chemical formula (h).

（式中、Ｒ¹⁹は水素原子、又は炭素数１〜６の直鎖状若しくは分岐を有するアルキル基又は脂環基を示す。）

(In the formula, R ¹⁹ represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or an alicyclic group.)

  The phosphorus-containing compound is added to the reaction system after being dissolved or dispersed in a monohydric alcohol such as methanol or ethanol, or a dihydric alcohol such as ethylene glycol, propylene glycol, or butylene glycol when the phosphorus-containing polyester resin is produced. preferable.

  In the present invention, the amount of the phosphorus-containing compound used is adjusted so that the content of phosphorus atoms derived from the phosphorus-containing compound in the obtained phosphorus-containing polyester resin is 300 ppm or more by weight ratio with respect to the total amount of the phosphorus-containing polyester resin. It is preferable that the amount be 500 ppm or more. In this way, particularly excellent flame retardancy and heat resistance can be imparted to the phosphorus-containing polyester resin. Further, the upper limit of the amount of the phosphorus-containing compound used is not particularly limited, but it is preferably blended in a range where the phosphorus atom content is 200,000 ppm or less. It can prevent and it can prevent that the resin characteristic of phosphorus containing polyester resin is impaired.

  Here, each of the above components used for obtaining the phosphorus-containing polyester resin is such that the total number of carboxyl groups and the ester-forming derivative groups thereof and the total number of hydroxyl groups and the ester-forming derivative groups thereof are included in each component. It is preferable to mix | blend so that it may become the range of 1: 1-1: 2.5 by molar ratio.

  In preparing the phosphorus-containing polyester resin, a known polyfunctional compound such as pentaerythritol, trimethylolpropane, dimethylolbutanoic acid, trifunctional carboxylic acid, etc. is appropriately used to adjust the molecular weight. It is also preferable to use an amount. In particular, when a compound containing one functional group (ester-forming functional group) is used as the phosphorus-containing compound, it may act as a terminal terminator, and therefore it is preferable to use the above polyfunctional compound in combination as appropriate.

  Moreover, as reaction components other than those described above, for example, p-hydroxybenzoic acid, monovalent aliphatic alcohol, and the like can be used together.

  The phosphorus-containing polyester resin can be obtained by a known polyester production method. For example, a direct esterification reaction using a dicarboxylic acid and a glycol or an ester exchange reaction between an ester-forming derivative of a dicarboxylic acid and a glycol is used as a first-stage reaction, and the second-stage reaction in which this reaction product is polycondensed can be produced. it can.

  Components other than the dicarboxylic acid component and the glycol component can be added to the reaction at any time from the beginning of the first stage reaction to the end of the second stage reaction.

  Next, the isocyanate curable resin will be described. By using the isocyanate-curable resin together with the above-described phosphorus-containing polyester resin, the isocyanate-curable resin expands due to heat when exposed to fire, thereby covering the side surface of the base sheet and a flame-retardant treatment layer. In order to suppress cracking due to flammable gas generated from the base sheet by forming a carbonized layer on the base sheet by using the inorganic flame retardant and layered silicate described later. Used for.

  Examples of the isocyanate curable resin include polyester polyol resin, acrylic polyol resin, polyurethane polyol resin, polyether polyol resin, and the like. From the viewpoint that it is difficult to cause cracks in the flame retardant layer. The transition temperature needs to be 60 ° C. or higher, preferably 70 ° C. or higher, and more preferably 90 ° C. or higher. Among such isocyanate curable resins, in consideration of the dispersibility of inorganic flame retardants and layered silicates described below, the curing temperature and time of the flame retardant treatment layer, adhesion to the base sheet, and handleability, etc. It is preferable to use an acrylic polyol resin.

  The ratio of the phosphorus-containing polyester resin and the isocyanate curable resin as described above is preferably 6: 4 to 8: 2 by weight. By setting the lower limit of the phosphorus-containing polyester resin and the upper limit of the isocyanate curable resin within such ranges, combustion of the resin component can be suppressed. Moreover, the side surface of a base material sheet is covered, and combustion from the base material sheet side surface can be suppressed. Moreover, since the followable | trackability to the base material sheet softened with the heat can be made favorable, it can be made hard to produce a crack in a flame-retardant-treated layer.

  In addition, by setting the upper limit of the phosphorus-containing polyester resin and the lower limit of the isocyanate curable resin within such a range, the isocyanate curable resin expands due to heat when exposed to fire, so that the side surface of the base sheet And making it difficult to cause cracks in the flame retardant layer. Moreover, by using with the inorganic flame retardant and layered silicate which are mentioned later, the carbonized layer can be formed on the surface of the base sheet, and the combustion by the combustible gas generated from the base sheet can be suppressed.

  As the curing agent for crosslinking and curing the phosphorus-containing polyester resin and the isocyanate curable resin as described above, an isocyanate curing agent is used. Isocyanate type curing agents include tolylene diisocyanate type, diphenylmethane diisocyanate type, xylylene diisocyanate type, isophorone diisocyanate type, hexamethylene diisocyanate type, etc., depending on the starting isocyanate, especially xylylene diisocyanate from the viewpoint of non-yellowing and weather resistance. A system, an isophorone diisocyanate system, and a hexamethylene diisocyanate system are preferably used.

  Next, the inorganic flame retardant will be described. The inorganic flame retardant promotes the formation of a carbonized layer on the surface of the base sheet when exposed to fire by using the above-described isocyanate curable resin and a layered silicate described later, and the isocyanate curable resin When the containing resin component expands due to heat, it moves with the expansion of the isocyanate curable resin and is used to impart flame retardancy to the surface and side surfaces of the base sheet.

  Examples of such inorganic flame retardants include silica, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, zirconium hydroxide, aluminum oxide, magnesium oxide, aluminum silicate, and lithium aluminum silicate. , Barium titanate, barium sulfate, silicon nitride, boron nitride, etc., and particularly when decomposed by heating to cause an endothermic reaction, and by forming water vapor and combustion products during this thermal decomposition, water vapor converts combustible gas. From the viewpoint of diluting the combustion products to form a carbonized layer, inorganic hydroxides such as aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and zirconium hydroxide are preferred, and particularly high flame retardancy. Magnesium hydroxide in that it is effective It is preferably used.

  Since the content of the inorganic flame retardant varies depending on the type and size of the selected inorganic flame retardant, it cannot be generally stated, but in the case of magnesium hydroxide, the resin component 100 weight excluding the isocyanate curing agent The lower limit is 50 parts by weight or more, and the upper limit is 90 parts by weight or less, preferably 80 parts by weight or less. By setting the magnesium hydroxide content to 50 parts by weight or more with respect to 100 parts by weight of the resin component excluding the isocyanate curing agent, flame retardant performance can be obtained, and 90 parts by weight or less. Therefore, it is possible to prevent cracks from being easily generated in the flame retardant treatment layer due to excessive inclusion of the inorganic flame retardant. Moreover, it can prevent that adhesiveness with a base material sheet falls.

  Further, the size of such magnesium hydroxide is not particularly limited, but it is preferable that the average particle diameter is 0.01 μm to 1 μm, more preferably 0.05 μm to 0.5 μm. By setting it as such a range, the effect of a high flame retardance can be acquired with the addition amount smaller than the case where magnesium hydroxide with a particle diameter exceeding 1 micrometer is used.

  Next, the layered silicate will be described. The layered silicate is used to prevent the flame retardant layer from being easily cracked starting from the inorganic flame retardant when the resin component containing the isocyanate curable resin expands. That is, the layered silicate in the flame retardant treatment layer plays a role of linking the isocyanate curable resin that expands when exposed to fire and the inorganic flame retardant.

  Examples of such layered silicates include kaolin minerals, mica clay minerals, smectites and mixed layer minerals. Among them, smectites are preferably used. Examples of smectites include trioctahedral smectites such as saponite, hectorite, saconite, stevensite, and swinolite, and dioctahedral smectites such as montmorillonite, beidellite, nontronite, and bolcon score. It is more preferable to use montmorillonite, which is a dioctahedral smectite, because it can make it difficult to cause cracks in the flame-retarded layer and has good compatibility (dispersibility) with the resin component described above.

  The content of the layered silicate in the flame retardant treatment layer varies depending on the type of the selected layered silicate, but it cannot be generally stated, but in the case of montmorillonite, the resin component is 100 parts by weight excluding the isocyanate curing agent. On the other hand, the lower limit is 5 parts by weight or more, preferably 7 parts by weight or more, and the upper limit is 15 parts by weight or less, preferably 13 parts by weight or less. By setting the content of montmorillonite to 5 parts by weight or more with respect to 100 parts by weight of the resin component excluding the isocyanate curing agent, when the resin component containing the isocyanate curable resin expands, the inorganic flame retardant is used as a starting point. It is possible to prevent the flame-retarded layer from being easily cracked, and by setting the content to 15 parts by weight or less, it is possible to prevent the flame-retarded layer from being easily cracked due to an excessive content of montmorillonite. it can. Moreover, it can prevent that adhesiveness with a base material sheet falls.

  In addition, the flame retardant layer in the present invention is within the range that does not impair the effects of the present invention, other fine particles, lubricants, fluorescent brighteners, dyes, pigments, antistatic agents, flame retardants, antibacterial agents, antibacterial agents. Various additives such as mold agents, ultraviolet absorbers, light stabilizers, antioxidants, plasticizers, leveling agents, flow regulators, antifoaming agents, dispersants, mold release agents, catalysts, and the like can be included.

  The thickness of the flame retardant treatment layer varies depending on the thickness and material of the base sheet, and thus cannot be generally stated. For example, when a polyester film having a thickness of 25 μm to 250 μm is used as the base sheet, the flame retardant The thickness of the chemical treatment layer is about 1 μm to 40 μm, preferably about 5 μm to 25 μm.

  Such a flame retardant treatment layer is added to both sides of the above-described base material sheet, as described above, including the phosphorus-containing polyester resin, isocyanate curable resin, isocyanate-based curing agent, inorganic flame retardant, layered silicate, and if necessary. In addition, other resin components, additives, and diluent solvents are mixed to mix the flame retardant layer coating solution, and conventionally known coating methods such as bar coaters, die coaters, blade coaters, spin coaters, roll coaters, It can be formed by applying and drying by a gravure coater, flow coater, spray, screen printing or the like, and curing and curing by applying heat.

  In addition, when the material of the base sheet is polyester, the flame retardant sheet of the present invention has an undercoat layer made of a phosphorus-containing polyester resin between the base sheet and the flame retardant treatment layer. You may do it.

  The phosphorus-containing polyester resin used in the undercoat layer can be the same as the phosphorus-containing polyester resin used in the flame-retardant treatment layer described above, and is preferably water-soluble. Further, as the phosphorus-containing compound used in the phosphorus-containing polyester resin, the compounds represented by the above general formulas (I) to (III) are preferable from the viewpoint of particularly easy reaction, flame retardancy, and the like. In particular, the compound represented by the general formula (I) is most suitable.

  Since the phosphorus-containing polyester resin is hard to burn and softens when exposed to fire, it is possible to wrap the combustible gas generated from the base sheet so that it does not touch the air. It is used to suppress combustion from the side surface of the sheet and to suppress combustion from the cracked portion when a crack occurs in the flame retardant layer. In addition, since the phosphorus-containing polyester resin is excellent in flexibility, the followability to the base sheet softened by heat can be improved, so that it is difficult to cause cracks in the flame-retardant treatment layer. .

  However, regarding the content of the phosphorus-containing polyester resin in the flame-retardant treatment layer, as described above, when the isocyanate-curable resin expands due to heat when exposed to fire, the flame-retardant treatment layer cracks. From the viewpoint of forming a carbonized layer on the surface of the base sheet by using it together with an inorganic flame retardant and a layered silicate, it is not preferable that the flame retardant layer is contained beyond the above-mentioned range. Therefore, by providing an undercoat layer made of a phosphorus-containing polyester resin between the base material sheet and the flame retardant treatment layer, the flame retardant treatment layer is compared with the flame retardant sheet having only the flame retardant treatment layer. It is possible to further suppress the combustion of the base sheet without the formation of the carbonized layer in.

  Moreover, since such an undercoat layer does not contain an acrylic polyol resin, an isocyanate curing agent, an inorganic flame retardant, a layered silicate, or the like, unlike the flame retardant treatment layer described above, from the side surface of the base sheet. The combustion of the base material sheet can be further suppressed. Moreover, since the followable | trackability to the base material sheet softened with the heat can be made more favorable, it can make it harder to produce a crack in a flame-resistant process layer. In addition, even if a crack is generated in the flame retardant layer, combustion from the cracked portion can be further suppressed.

  The thickness of such an undercoat layer is not particularly limited, but is about 0.5 μm to 5 μm, preferably about 1 μm to 3 μm, from the viewpoint of obtaining the above-described effects and economical efficiency.

  As described above, according to the present invention, the phosphorus-containing polyester resin, the resin component comprising the isocyanate curable resin having a glass transition temperature of 60 ° C. or higher, and the isocyanate curing agent and the inorganic flame retardant are provided on both surfaces of the base sheet. By having a flame retardant treatment layer composed of a layered silicate, it is difficult to suppress combustion due to a flammable gas generated by thermal decomposition of the substrate sheet from cracks in the side surface of the substrate sheet or the flame retardant treatment layer. A flammable sheet can be obtained.

  Further, when an undercoat layer made of a phosphorus-containing polyester resin is provided between at least one surface of the base sheet and the flame retardant layer, the side surface of the base sheet or the flame retardant layer It is possible to obtain a flame retardant sheet in which combustion by a combustible gas generated by thermal decomposition of the base sheet from the cracks is further suppressed.

  Hereinafter, the present invention will be described in more detail based on examples. In this example, “parts” and “%” are based on weight unless otherwise specified.

[Examples 1 to 12]
The coating liquid for flame retardant treatment of the formulation shown in Table 1 was applied to both surfaces of a 100 μm thick polyester film (Lumirror T60: Toray Industries, Inc.) as a base sheet and dried at 110 ° C. for 2 minutes. Thereafter, curing was performed at 60 ° C. for 40 hours to form a flame-retardant layer having a thickness of 12 μm, and flame-retardant sheets of Examples 1 to 12 were produced.

[Comparative Examples 1 to 9]
A polyester film similar to that of the example was used as the base sheet, and the flame retardant treatment layer coating solution of the formulation in Table 2 was used instead of the flame retardant treatment layer coating solution of the example. Similarly, the flame-retardant sheet | seat of Comparative Examples 1-9 was produced.

The materials and symbols in Tables 1 and 2 are shown below.
・ Phosphorus-containing polyester resin A (GX300: Mutual Chemicals)
・ Phosphorus-containing polyester resin B (GX436: Mutsumi Chemical Co., Ltd.)
・ Polyester resin C (Byron 500: Toyobo Co., Ltd.)
・ Acrylic polyol resin A (Acridic UV-191: Dainippon Ink, Inc.)
・ Acrylic polyol resin B (Acridic A-814: Dainippon Ink)
・ Acrylic polyol resin C (Acridic WBU-1218: Dainippon Ink)
・ Acrylic polyol resin D (Acridic DL-967: Dainippon Ink)
・ Isocyanate curing agent (WB-40-100: Asahi Kasei Chemicals Corporation)
Magnesium hydroxide, Mg (OH) ₂ (average particle size 0.1 μm: MGZ-4: Sakai Chemical Industry Co., Ltd.)
・ Montmorillonite (New D Orben: Shiroishi Kogyo Co., Ltd.)
・ Hectorite (Lucentite STN: Corp Chemical)
・ Smectite (montmorillonite or hectorite)
・ Tg (Glass transition temperature)

  About the flame-retardant sheet | seat of the Example and the comparative example, the flammability test was done and the flame-retardant performance was evaluated.

  Samples obtained by cutting out the flame-retardant sheets of Examples and Comparative Examples into strips of 50 mm × 200 mm were used as samples, and each sample was rolled into a cylinder with a diameter of 12.7 mm and a length of 200 mm. The cylindrical sample was held so that the longitudinal direction was perpendicular to the ground, the upper end in the longitudinal direction was held, the lower end was exposed to a flame of about 20 mm for 3 seconds, and then released. At this time, the burning time of the sample after flame release was measured (burning time at the first flame contact).

  Next, when the sample was extinguished without burning out, the second flame contact / flame was performed after the fire extinguishing in the same manner as the first, and the burning time of the film after the flame release was measured (at the time of the second flame contact) Burning time). This test was repeated with n number = 5.

  The evaluation is “◎” for self-extinguishing in less than 50 seconds with self-extinguishing in less than 50 seconds, with the total combustion time at the first and second flame contact of n number = 5 being three stages, and self-extinguishing in 50 to less than 60 seconds "○" for those that were self-extinguishing for 60 seconds or more and less than 74 seconds, "△" for those that self-extinguished for 74 seconds or more, "X", those that burned up to the top of the sample without self-extinguishing Was “XX”. The results are shown in Tables 1 and 2.

  From Table 1, the flame-retardant sheet of an Example consists of the resin component which consists of a phosphorus containing polyester resin, an isocyanate curable resin, and an isocyanate hardening agent, an inorganic flame retardant, and layered silicate on both surfaces of a base material sheet. Since it has a flame retardant treatment layer, it has flame retardant performance.

  In particular, the flame retardant sheets of Examples 2, 3, 4, 6, 7, 9, 10, and 11 have acrylic flame polyol as the isocyanate curable resin having a glass transition temperature of 60 ° C. or higher, with the configuration of the flame retardant layer. The ratio of the phosphorus-containing polyester resin and the acrylic polyol resin in the flame retardant layer is 6: 4 to 8: 2 by weight, and montmorillonite that is dioctahedral smectite is used as the layered silicate. The content of magnesium hydroxide is 5 to 15 parts by weight with respect to 100 parts by weight of the resin component excluding the isocyanate curing agent, and the average particle diameter is 0.01 μm to 1 μm as an inorganic flame retardant. The content of the resin component is 50 to 90 parts by weight with respect to 100 parts by weight of the resin component excluding the isocyanate curing agent, and thus has excellent flame resistance performance. It became something to do. In particular, the flame retardant sheet of Example 3 had the most excellent flame retardant performance because the above configuration was within the most preferable range.

  Moreover, since the flame retardant sheet of Example 12 uses hectorite, which is trioctahedral smectite, as the layered silicate, the flame retardant sheet is inferior to the flame retardant sheet of Example 3, but has excellent flame retardant performance. It became.

  Next, from Table 2, since the flame retardant sheets of Comparative Examples 1 and 2 did not have a layered silicate, they were cracked in the flame retardant treatment layer starting from an inorganic flame retardant when exposed to fire. As a result, combustion by the combustible gas generated from the base sheet could not be prevented, and the flame retardant performance was inferior to that of the Examples.

  Moreover, since the flame-retardant sheet | seat of Comparative Examples 3-6 was only a phosphorus containing polyester resin as a resin component, and it did not have an isocyanate curable resin whose glass transition temperature is 60 degreeC or more, when exposed to fire, Because the resin component does not expand due to heat and cracks occur in the flame retardant treatment layer, combustion due to the combustible gas generated from the base sheet cannot be prevented, and the formation of the carbonized layer is insufficient The flame retardant performance was inferior to that of the example.

  In addition, since the flame retardant sheet of Comparative Example 7 uses a polyester resin that does not contain phosphorus as a resin component in place of the phosphorus-containing polyester resin, the resin itself easily burns, and is incombustible compared to the examples. The performance of the sex became inferior.

  The flame retardant sheet of Comparative Example 8 uses an isocyanate curable resin having a glass transition temperature of less than 60 ° C. as the resin component. Therefore, when the resin component expands due to heat, the coating strength is low and the flame retardant treatment layer is used. As a result, cracks occurred and combustion by the combustible gas generated from the base material sheet could not be prevented, resulting in inferior flame retardant performance as compared with Examples.

  Further, the flame retardant sheet of Comparative Example 9 is only an isocyanate curable resin having a glass transition temperature of 60 ° C. or higher as a resin component, and does not have a phosphorus-containing polyester resin, so the resin component itself burns. The flame retardant performance was inferior to that of the example.

Claims (10)

  A flame retardant treatment layer comprising a phosphorus-containing polyester resin, an isocyanate curable resin having a glass transition temperature of 60 ° C. or higher, a resin component comprising an isocyanate curing agent, an inorganic flame retardant, and a layered silicate on both sides of the substrate sheet A flame retardant sheet characterized by comprising:   The flame retardant sheet according to claim 1, wherein the layered silicate is smectite.   The flame retardant sheet according to claim 2, wherein the smectite is montmorillonite.   4. The content of the layered silicate is 5 to 15 parts by weight with respect to 100 parts by weight of the resin component excluding the isocyanate curing agent. Flame retardant sheet. The flame-retardant sheet according to any one of claims 1 to 4, wherein the phosphorus-containing polyester resin contains a phosphorus-containing compound represented by the following general formula (I).

(In the formula, R ^{1 to} R ⁸ each represent a hydrogen atom or an organic group, and may be the same or different. A represents a hydrogen atom or an organic group, and R ^{1 to} R ⁸ may be the same as or may be different. However, at least one of R ¹ to R ⁸ and a is an ester-forming functional group.)   The flame retardant sheet according to any one of claims 1 to 5, wherein the isocyanate curable resin is an acrylic polyol resin.   The ratio of the said phosphorus containing polyester resin and the said isocyanate curable resin in the said flame-retardant process layer is 6: 4-8: 2 by weight ratio, The any one of Claim 1 to 6 characterized by the above-mentioned. Flame retardant sheet.   The flame retardant sheet according to any one of claims 1 to 7, wherein the inorganic flame retardant is magnesium hydroxide.   The content of the magnesium hydroxide in the flame retardant treatment layer is 50 parts by weight to 90 parts by weight with respect to 100 parts by weight of the resin component excluding the isocyanate curing agent. Flame retardant sheet. The flame retardant sheet according to claim 8 or 9, wherein the magnesium hydroxide has an average particle size of 0.01 µm to 1 µm.