Flame-retardant resin composition

Abstract

This flame-retardant resin composition comprises a thermosetting resin and a flame-retarding agent, and has a ΔEr value of 30 or less as determined by the following procedure. Procedure: (i) A test plate (size: 120 mm square, 2 mm in thickness) under the conditions including a mold temperature of 175°C and a curing time of 3 minutes is prepared using the flame-retardant resin composition. (ii) A torch burner (30 mm with respect to a flame length of about 100 mm) is set to the center of one surface of the vertically-set test plate such that the angle with respect to the test plate becomes 90°, and a flame from the torch burner is applied to the center for 5 minutes. (iii) For the center of the other surface of the test plate and two points which are located on a straight line passing through the center of the other surface of the test plate and are each 3 mm away from this center, color differences between before and after the contact with the flame are separately measured and an average value (ΔEr) is determined.

Description

Flame-retardant resin composition

[0001] The present invention relates to a flame-retardant resin composition, and more particularly to a flame-retardant resin composition and an in-vehicle part comprising a cured product of the flame-retardant resin composition.

[0002] In recent years, the development of electric vehicles and hybrid vehicles driven by electric motors has been actively promoted from the viewpoint of environmental protection. In battery packs mounted on such electric vehicles and hybrid vehicles, a fire in one of the batteries can cause adjacent batteries to ignite one after another. To address this issue, for example, Patent Document 1 (JP 2023-146688 A) discloses that the exterior of a case housing the batteries is covered with a resin containing a flame retardant.

[0003] On the other hand, as one of the techniques for improving the flame retardancy of a resin composition, an example of adding a compound called a flame retardant has been proposed. Examples of flame retardants used in resin compositions include inorganic flame retardants such as metal hydroxides (see, for example, Patent Document 2 (WO 2020 / 080149)).

[0004] Here, the UL94 standard has been known as one of the indicators of flame retardancy. The UL94 standard is a standard for evaluating the flame retardancy of plastic products and is widely adopted worldwide. The UL94 standard includes 5VA, 5VB, V-0, V-1, V-2, and HB, in order of decreasing flame retardancy. For example, in the V-0 test, a flame is exposed to the material twice for 10 seconds.

[0005] JP 2023-146688 A International Publication No. 2020 / 080149

[0006] Demand for flame retardancy in flame retardant materials is increasing along with improved safety awareness, growing demand for higher performance, etc. Therefore, conventional flame retardant materials such as those disclosed in Patent Documents 1 and 2 have room for improvement in terms of obtaining higher flame retardancy.

[0007] The present inventors have conducted extensive research to achieve even higher flame retardancy, and have found that even if a resin has good flame retardancy according to the UL94 standard, the flame retardancy is insufficient when exposed to flame for a longer period of time or when the flame is stronger. As a result of further research, they have devised a new index for flame retardancy and found that it is effective to produce a flame-retardant resin composition that satisfies this index, thereby completing the present invention.

[0008] According to the present invention, the following flame-retardant resin composition and related art are provided.

[0009] [1] A flame-retardant resin composition containing a thermosetting resin and a flame retardant, the flame-retardant resin composition having a ΔEr of 30 or less, as obtained by the following procedure: (i) Using the flame-retardant resin composition, a test plate (120 mm square, 2 mm thick) is prepared under conditions of a mold temperature of 175°C and a curing time of 3 minutes. (ii) A torch burner (30 mm from a flame length of approximately 100 mm) is applied to the center of one side of the vertically held test plate at a 90° angle to the test plate, and the flame is applied for 5 minutes. (iii) The color difference between before and after flame application is measured at the center of the other side of the test plate and at two points 3 mm from the center on a line passing through the center of the other side, and the average color difference (ΔEr) is calculated. [2] The flame-retardant resin composition according to [1], wherein the flame retardant includes one or more flame retardants selected from organic flame retardants and inorganic flame retardants. [3] The flame-retardant resin composition according to [1] or [2], further comprising an inorganic filler. [4] The flame-retardant resin composition according to any one of [1] to [3], wherein the color differences before and after exposure to flame are measured at the center of one side of the test panel obtained in step (ii) and at two points on a line passing through the center of the one side and 3 mm from the center, and the average color difference (ΔEf) is calculated, and the average color difference (ΔEf) is calculated, and the average color difference (ΔEf) is 0 to 100. [5] The flame-retardant resin composition according to any one of [1] to [4], wherein the content of the flame retardant is 1 to 45 parts by mass per 100 parts by mass of the flame-retardant resin composition. [6] The flame-retardant resin composition according to any one of [1] to [5], wherein the thermosetting resin comprises one or more selected from the group consisting of a phenolic resin, a diallyl phthalate resin, an unsaturated polyester resin, an epoxy resin, a melamine resin, and a furan resin. [7] The flame-retardant resin composition according to [3], wherein the inorganic filler is one or more selected from the group consisting of a fibrous filler, a plate-like filler, and a spherical filler.[8] The flame-retardant resin composition according to [3] or [7], wherein the inorganic filler is one or more selected from glass fiber, carbon fiber, metal fiber, and mineral filler. [9] The flame-retardant resin composition according to [3], [7], or [8], wherein the content of the inorganic filler is 30 to 85 parts by mass per 100 parts by mass of the flame-retardant resin composition.

[10] The flame-retardant resin composition according to any one of [1] to [9], wherein a test panel (size 125 mm x 13 mm, thickness 0.75 mm) is prepared using the flame-retardant resin composition at a mold temperature of 175°C and a curing time of 3 minutes, and the test panel satisfies UL-94 V-1 in a test according to the UL-94 standard.

[11] The flame-retardant resin composition according to any one of [1] to

[10] , wherein the flame-retardant resin composition is used for an in-vehicle part.

[12] A cured product of the flame-retardant resin composition according to any one of [1] to

[11] .

[13] An in-vehicle part comprising a cured product of the flame-retardant resin composition according to

[11] .

[0010] According to the present invention, there is provided a flame-retardant resin composition having improved flame retardancy.

[0011] Photographs showing the results of the flame retardancy evaluation of the test plate of Example 1. Photographs showing the results of the flame retardancy evaluation of the test plate of Example 2. Photographs showing the results of the flame retardancy evaluation of the test plate of Comparative Example 1. Photographs showing the results of the flame retardancy evaluation of the test plate of Comparative Example 2.

[0012] Hereinafter, embodiments of the present invention will be described in detail.

[0013] In this specification, the expression "a to b" in the description of a numerical range means from a to b, unless otherwise specified. For example, "1 to 5% by mass" means "1% by mass or more and 5% by mass or less."

[0014] <Flame-Retardant Resin Composition> The flame-retardant resin composition of the present embodiment contains a thermosetting resin and a flame retardant, and has a ΔEr of 30 or less obtained by the following procedure.

[0015] Procedure: (i) Using the flame-retardant resin composition, a test plate (120 mm square, 2 mm thick) was prepared under conditions of a mold temperature of 175°C and a curing time of 3 minutes. (ii) A torch burner (30 mm from a flame length of approximately 100 mm) was applied to the center of one side of the vertically held test plate at an angle of 90° to the test plate, and the flame was applied for 5 minutes. (iii) The color difference before and after exposure to flame was measured at the center of the other side of the test plate and at two points 3 mm from the center on a line passing through the center of the other side, and the average value (ΔEr) was calculated.

[0016] In other words, the ΔEr is a new index devised by the present inventors, and by producing a flame-retardant resin composition so as to satisfy this index, high flame retardancy can be obtained.

[0017] Here, the UL94 standard is one example of an index of flame retardancy. While the burner used in the V-0 standard has a heat output of 0.05 kW, the torch burner used in step (ii) of the present embodiment has a heat output of 2 to 4 kW. ΔEr is the color difference between before and after flame exposure at three predetermined points on the non-flame-contacted surface of the test plate. That is, a low ΔEr value indicates that the discoloration on the back surface of the test plate is small before and after flame exposure on the front surface of the test plate, which indicates that the test plate is less flammable. In other words, when flame retardancy is low, flame and heat easily reach the back surface (non-flame-contacted surface), resulting in greater discoloration and incineration on the back surface of the test plate. Therefore, by controlling the ΔEr obtained by the above procedure, the flame-retardant resin composition of the present embodiment achieves high flame retardancy from a different perspective than conventional methods against flames with higher heat output.

[0018] ΔEr is equal to or less than 30, preferably equal to or less than 25, and more preferably equal to or less than 22. By making ΔEr equal to or less than the above upper limit, higher flame retardancy can be obtained.

[0019] Furthermore, the color difference before and after exposure to flame is measured at the center of one surface of the test panel obtained in step (ii) and at two points on a line passing through the center of the one surface and 3 mm from the center, and the average value (ΔEf) is calculated, and ΔEf is preferably 1 to 100, more preferably 10 to 80, and even more preferably 20 to 70. By setting ΔEf to the above upper limit or less, good flame retardancy is achieved.

[0020] That is, ΔEf is the color difference before and after flame contact at three predetermined points on the flame-contacted surface of the test plate. That is, a low ΔEf value means that there is little discoloration on the surface of the test plate before and after the surface of the test plate is contacted with a flame, which indicates that the test plate is less flammable.

[0021] In the above (ii), the torch burner is applied to the center of the test plate, and the flame applied to the test plate may extend approximately 20 mm (approximately 40 mm in diameter) from the center. In the above (iii), the color difference is measured at three points: the center of the test plate and two points 3 mm from the center and symmetrical to each other. The color difference is measured after the temperature of the test plate has returned to room temperature after application of the flame.

[0022] ΔE (ΔEr and ΔEf) can be achieved by selecting and adjusting the blending of materials constituting the flame-retardant resin composition, or by devising a manufacturing method, as will be described in detail later. Examples of such methods include selecting an organic flame retardant, selecting the type of inorganic filler, adjusting the blending ratio of the inorganic filler and the thermosetting resin, and controlling the number of roll kneading cycles when mixing the materials.

[0023] The color difference (ΔE) is measured as follows: At set measurement points, a color difference meter is used to measure the color difference according to CIE 1976L. ＊ a ＊ b ＊ Chromaticity coordinates (L ＊ , a ＊ , b ＊ The chromaticity coordinates measured on the test plate before exposure to flame are (L ＊ 0, a ＊ 0, b ＊0), and the chromaticity coordinates measured on the test plate after contact with the flame are (L ＊ 1. a ＊ 1, b ＊ 1), and ΔE can be calculated by applying the obtained values ​​to the following formula: ΔEr = [(L ＊ 1-L ＊ 0) ２ + (a ＊ 1-a ＊ 0) ２ +(b ＊ 1-b ＊ 0) ２ 〕 １／２

[0024] Furthermore, the flame-retardant resin composition of this embodiment preferably satisfies UL-94 V-1. This allows for more stable high flame retardancy. Specifically, a test plate (size 125 mm x 13 mm, thickness 0.75 mm) is prepared using the flame-retardant resin composition of this embodiment under conditions of a mold temperature of 175°C and a curing time of 3 minutes, and a test is performed in accordance with the UL-94 standard.

[0025] The components constituting the flame-retardant resin composition will be described below.

[0026] [Flame Retardant] A flame retardant is a compound used to make a thermosetting resin flame-retardant. Flame retardants are classified into organic flame retardants and inorganic flame retardants depending on their constituent components. In the flame-retardant resin composition of this embodiment, the flame retardant may be an organic flame retardant, an organic flame retardant, or a mixture thereof.

[0027] (Organic Flame Retardant) Examples of the organic flame retardant include phosphorus-based flame retardants, silicone-based flame retardants, halogen-based flame retardants, etc. Among these, it is preferable that the organic flame retardant contains a phosphorus-based flame retardant or a silicone-based flame retardant.

[0028] Phosphorus-based flame retardants form char upon combustion. Examples of phosphorus-based flame retardants include one or more selected from red phosphorus, phosphate esters such as trimethyl phosphate (TMP), triethyl phosphate (TEP), triphenyl phosphate (TPP), trixylenyl phosphate (TXP), tributyl phosphate (TBP), tricresyl phosphate (TCP), and cresyl diphenyl phosphate (CDP), halogen-containing organic phosphoric acid compounds such as tris(2-chloroethyl)phosphate (TCEP), tris(1-chloro-2-propyl)phosphate (TCPP), and tris(1,3-dichloro-2-propyl)phosphate (TDCPP), polyphosphate compounds such as polychlorophosphonates and ammonium polyphosphate (APP), and inorganic polyphosphate compounds.

[0029] Silicone compounds, which are silicone-based flame retardants, improve flame retardancy through a chemical reaction during combustion. Examples of the silicone compound include one or more selected from silicone resins, silicone rubbers, silicone oils, etc.

[0030] The silicone compound is SiO ２ , R—SiO ３／２ , R-SiO, R-SiO １／２ Examples of suitable organic residues include resins having a three-dimensional network structure formed by combining structural units such as those shown above. R represents an alkyl group such as a methyl group, an ethyl group, or a propyl group; an aromatic group such as a phenyl group or a benzyl group; or a substituent containing a vinyl group in the aforementioned substituent. Silicone compounds may be linear or branched. Furthermore, the organic residue bonded to the silicon atom preferably has 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms. Specific examples of such organic residues include alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and a decyl group; cycloalkyl groups such as a cyclohexyl group; aryl groups such as a phenyl group; and aralkyl groups such as a tolyl group. More preferred are alkyl groups, alkenyl groups, or aryl groups having 1 to 8 carbon atoms.

[0031] (Inorganic Flame Retardant) Examples of the inorganic flame retardant include one or more selected from metal hydroxide flame retardants, boron flame retardants, and antimony oxide flame retardants.

[0032] Metal hydroxide flame retardants emit little smoke during combustion and can release water at high temperatures. Examples of metal hydroxide flame retardants include one or more selected from magnesium hydroxide, aluminum hydroxide, barium hydroxide, and calcium hydroxide. Examples of boron flame retardants include one or more selected from calcium borate and zinc borate. Examples of antimony oxide flame retardants include one or more selected from antimony trioxide and antimony pentoxide. Among these, magnesium hydroxide, aluminum hydroxide, and zinc borate are preferred as inorganic flame retardants.

[0033] The content of the flame retardant is preferably 1 to 45 parts by mass, more preferably 2 to 40 parts by mass, and even more preferably 3 to 35 parts by mass, per 100 parts by mass of the flame-retardant resin composition. By setting the content of the flame retardant to the above-mentioned lower limit or more, flame retardancy is easily improved. On the other hand, by setting the content of the flame retardant to the above-mentioned upper limit or less, the function of the thermosetting resin is easily exhibited while maintaining flame retardancy.

[0034] When an organic flame retardant is used, the content thereof is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and even more preferably 3 to 10 parts by mass, per 100 parts by mass of the flame-retardant resin composition. By setting the content of the organic flame retardant to the above-mentioned lower limit or more, flame retardancy is easily improved. On the other hand, by setting the content of the organic flame retardant to the above-mentioned upper limit or less, the function of the thermosetting resin is easily exhibited while maintaining flame retardancy.

[0035] When an inorganic flame retardant is used, the content thereof is preferably 10 to 45 parts by mass, more preferably 15 to 40 parts by mass, and even more preferably 18 to 35 parts by mass, per 100 parts by mass of the flame-retardant resin composition. By setting the content of the inorganic flame retardant to the above-mentioned lower limit or more, flame retardancy is easily improved. On the other hand, by setting the content of the inorganic flame retardant to the above-mentioned upper limit or less, the function of the thermosetting resin is easily exhibited while maintaining flame retardancy.

[0036] (Thermosetting Resin) The thermosetting resin may be one or more selected from phenolic resin, diallyl phthalate resin, unsaturated polyester resin, epoxy resin, melamine resin and furan resin, with phenolic resin being preferred.

[0037] Specific examples of the phenolic resin include novolac-type phenolic resins, resole-type phenolic resins, and aryl alkylene-type phenolic resins. As the phenolic resin, one of these may be used alone, or two or more types having different weight-average molecular weights may be used in combination, or one or more types may be used in combination with their prepolymers. Among these, resole-type phenolic resins are preferred.

[0038] The diallyl phthalate resin is a prepolymer synthesized from a diallyl phthalate monomer or a diallyl isophthalate monomer. Depending on the orthophthalic and isophthalic monomers, diallyl orthophthalate resins and diallyl isophthalate resins are available.

[0039] The use of a diallyl phthalate resin containing diallyl phthalate, an ester of phthalic acid and allyl alcohol, as a constituent monomer and polymerized at the allyl group of the diallyl phthalate, particularly a diallyl isophthalate resin in which the phthalic acid is isophthalic acid, can improve heat resistance. Furthermore, by keeping the content of the diallyl isophthalate resin relatively low and increasing the content of aluminum hydroxide relatively high, tracking resistance can be improved, thereby achieving both tracking resistance and flame retardancy at a higher level.

[0040] In this embodiment, the diallyl isophthalate resin includes not only those containing diallyl isophthalate, an ester of isophthalic acid and allyl alcohol, as a constituent monomer and having a structure polymerized at the allyl group of diallyl isophthalate, but also those in which at least a portion of the diallyl isophthalate as a constituent monomer is substituted with a compound in which at least a portion of the hydrogen atoms on the benzene ring of isophthalic acid are substituted with a halogen atom such as chlorine or bromine, or those in which the unsaturated bonds present in the molecule of diallyl isophthalate / substituted diallyl isophthalate are substituted with a compound in which all or a portion of the unsaturated bonds are hydrogenated.

[0041] Specific examples of epoxy resins include biphenyl-type epoxy resins; bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AD-type epoxy resins, and tetramethylbisphenol F-type epoxy resins; stilbene-type epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins and cresol novolac-type epoxy resins; polyfunctional epoxy resins such as triphenyl-type epoxy resins exemplified by triphenolmethane-type epoxy resins and alkyl-modified triphenolmethane-type epoxy resins; phenol aralkyl-type epoxy resins having a phenylene skeleton, naphthol aralkyl-type epoxy resins having a phenylene skeleton, and phenol aralkyl-type epoxy resins having a biphenylene skeleton. phenol aralkyl epoxy resins such as aryl-type epoxy resins (biphenyl aralkyl-type epoxy resins) and naphthol aralkyl-type epoxy resins having a biphenylene skeleton; naphthol-type epoxy resins such as dihydroxynaphthalene-type epoxy resins and epoxy resins obtained by glycidyl etherifying a dihydroxynaphthalene dimer; triazine nucleus-containing epoxy resins such as triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate; bridged cyclic hydrocarbon compound-modified phenol-type epoxy resins such as dicyclopentadiene-modified phenol-type epoxy resins; brominated epoxy resins such as brominated bisphenol A and brominated phenol novolac; tris(hydroxyphenyl)methane-type epoxy resins. As the epoxy resin, one type from these may be used alone, or two or more different types may be used in combination.

[0042] Specific examples of unsaturated polyester resins include thermosetting resins obtained by reacting an unsaturated dibasic acid such as maleic anhydride and a saturated dibasic acid such as phthalic anhydride with glycols to condense them, and these resins are usually used in the form of a solution in a polymerizable monomer such as styrene.

[0043] More specifically, the unsaturated polyester resin may be one or more phthalic acid-based unsaturated polyester resins selected from the group consisting of an ortho-type resin obtained by reacting phthalic anhydride or orthophthalic acid with glycols and condensing the resulting saturated dibasic acid and glycolic acid, an iso-type resin obtained by reacting isophthalic acid with glycols and condensing the resulting isophthalic acid, and a para-type resin obtained by reacting terephthalic acid with glycols and condensing the resulting terephthalic acid. The unsaturated polyester resin is preferably one or more phthalic acid-based unsaturated polyester resins selected from the group consisting of a tere-type resin obtained by reacting terephthalic acid with glycols and an iso-type resin obtained by reacting isophthalic acid with glycols.

[0044] The unsaturated polyester resin includes, for example, at least one of the teletype and isotype phthalic acid-based unsaturated polyester resins. The unsaturated polyester resin may also include the teletype and isotype phthalic acid-based unsaturated polyester resins. When the unsaturated polyester resin includes the teletype and isotype phthalic acid-based unsaturated polyester resins, the proportion of the isotype is, for example, 40 parts by mass or more, or 50 parts by mass or more, or 55 parts by mass or more, per 100 parts by mass of the total of the teletype and isotype. Specifically, the proportion may be less than 100 parts by mass, for example, 80 parts by mass or less.

[0045] The content of the thermosetting resin is preferably 10 to 50 parts by mass, more preferably 15 to 45 parts by mass, and even more preferably 20 to 38 parts by mass, per 100 parts by mass of the flame-retardant resin composition. By setting the content of the thermosetting resin to the above-mentioned lower limit or more, flame retardancy and processability can be improved. By setting the content of the thermosetting resin to the above-mentioned upper limit or less, it is easier to achieve a high level of UL-94 standard while maintaining flame retardancy against high-heat flames.

[0046] [Inorganic Filler] The flame-retardant resin composition may further contain an inorganic filler. The inorganic filler is an inorganic substance other than the inorganic flame retardants described above, and is used to increase the mechanical strength and flame retardancy of the cured product of the flame-retardant resin composition.

[0047] The inorganic filler is preferably one or more types selected from the group consisting of fibrous fillers, plate-like fillers, and spherical fillers, in terms of their shape.

[0048] The fibrous filler is a short fiber, and may be one or more types selected from metal fibers, carbon fibers, glass fibers, and ceramic fibers. Of these, metal fibers, carbon fibers, and glass fibers are preferred, and glass fibers are more preferred.

[0049] The plate-like filler may be, for example, a filler having an aspect ratio of 3 or more, and the spherical filler may be a filler that is a perfect sphere or a nearly perfect sphere and has an aspect ratio of less than 3, for example.

[0050] Examples of materials constituting the spherical or plate-like filler include minerals such as talc, mica, halloysite, kaolin, illite, montmorillonite, vermiculite, palygorskite, pyrophyllite, beidellite, nontronite, saponite, hectorite, sauconite, calcium silicate, aluminum silicate, wollastonite, glass flakes, molybdenum sulfide, and wollastonite; sulfates such as potassium sulfate, aluminum sulfate, sodium sulfite, calcium sulfate, and barium sulfate; carbonates such as calcium carbonate and magnesium carbonate; metal oxides such as aluminum oxide (alumina); crystalline or fused silica, surface-treated silica; and glass beads. These may be used alone or in combination. For example, a fibrous filler and a plate-like filler may be used in combination.

[0051] The content of the inorganic filler is preferably 30 to 85 parts by mass, more preferably 35 to 80 parts by mass, and even more preferably 38 to 75 parts by mass, per 100 parts by mass of the flame-retardant resin composition. By setting the content of the inorganic filler to the above-mentioned lower limit or more, it is possible to obtain flame retardancy according to the UL94 standard while also improving flame retardancy for higher heat values. On the other hand, by setting the content of the inorganic filler to the above-mentioned upper limit or less, good flame retardancy for high heat values ​​can be obtained.

[0052] [Others] Furthermore, the flame-retardant resin composition may contain known compounds depending on the intended use. Examples of known compounds include additives such as curing aids, polymerization initiators, polymerization inhibitors, curing agents, coupling agents, surfactants, curing accelerators, elastomers, pigments, and adhesion improvers. Only one of these may be contained, or two or more may be contained.

[0053] (Curing Aid) Examples of the curing aid include curing aids known in the field of resin compositions. Examples include oxides or hydroxides of alkaline earth metals such as magnesium oxide, calcium hydroxide, and barium hydroxide; and aromatic carboxylic acids such as salicylic acid and benzoic acid. The alkaline earth metal oxides or hydroxides can also be used as inorganic flame retardants. When a curing aid is used, the content of the curing aid is preferably, for example, 1 to 10 parts by mass per 100 parts by mass of the thermosetting resin.

[0054] (Polymerization initiator) A polymerization initiator is used to initiate polymerization. An organic peroxide is preferred as the polymerization initiator. Examples of the organic peroxide include one or more selected from ketone peroxides, peroxyketals, hydroperoxides, hydroxyperoxides, diallyl peroxides, diacyl peroxides, peroxyesters, and peroxydicarbonates. When a polymerization initiator is used, the content of the polymerization initiator is preferably 1 to 10 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of the thermosetting resin.

[0055] (Curing Agent) The curing agent is selected depending on the type of thermosetting resin, and is not particularly limited as long as it reacts with the thermosetting resin. Specific examples of the curing agent include polyaddition type curing agents, catalyst type curing agents, and condensation type curing agents.

[0056] Specific examples of the curing agent include phenolic curing agents; amines; polyoxystyrenes such as polyparaoxystyrene; alicyclic acid anhydrides such as hexahydrophthalic anhydride (HHPA) and methyltetrahydrophthalic anhydride (MTHPA), and acid anhydrides including aromatic acid anhydrides such as trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), and benzophenonetetracarboxylic acid (BTDA); polymercaptan compounds such as polysulfides, thioesters, and thioethers; isocyanate compounds such as isocyanate prepolymers and blocked isocyanates; organic acids such as carboxylic acid-containing polyester resins; and hexamethylenetetramine. One or more of these may be used in combination. The content of the thermosetting resin and curing agent is appropriately determined depending on the type of thermosetting resin and curing agent.

[0057] (Coupling Agent) When an inorganic filler is contained, a coupling agent may be further contained. This can suppress aggregation of the inorganic filler and obtain good fluidity. As the coupling agent, known coupling agents such as various silane-based compounds such as epoxysilane, mercaptosilane, aminosilane, alkylsilane, ureidosilane, and vinylsilane, titanium-based compounds, aluminum chelates, and aluminum / zirconium-based compounds can be used.

[0058] (Elastomer) Examples of elastomers include acrylonitrile butadiene rubber, isoprene, styrene butadiene rubber, and ethylene propylene rubber. Among these, acrylonitrile butadiene rubber is preferred. Use of an elastomer can improve the toughness of the cured product of the flame-retardant resin composition. When using an elastomer, the content of the elastomer is preferably, for example, 2 to 15 parts by mass per 100 parts by mass of the thermosetting resin.

[0059] (Release Agent) Examples of the release agent include fatty acids such as stearic acid, fatty acid salts such as calcium stearate and zinc stearate, fatty acid amides, polyethylene, etc. When a release agent is used, the content of the release agent is, for example, 1 to 10 parts by mass, and preferably 2 to 8 parts by mass, relative to 100 parts by mass of the thermosetting resin.

[0060] (Pigment) Examples of pigments include carbon black. In addition, various coloring pigments can be used to obtain molded products of desired colors. When a pigment is used, the amount of the pigment is, for example, 0.5 to 10 parts by mass, preferably 1 to 5 parts by mass, per 100 parts by mass of the thermosetting resin.

[0061] Next, a method for producing the flame-retardant resin composition of this embodiment will be described. The method for producing the flame-retardant resin composition of this embodiment is not particularly limited. For example, when the thermosetting component and other optional components are liquid, they are mixed by stirring with a stirring spring using a Three-One motor or the like. Alternatively, when the thermosetting component and other optional components are solid, they are mixed using a mixer or the like, and then melt-heated and kneaded at approximately 90 to 120°C using a heated kneader, heated roll, or extruder. Preferred conditions for the heated kneading are, for example, 20 to 40 rolls and a rotation speed of 14 to 20 rpm. The resulting kneaded product is then cooled and pulverized to obtain a powdered or granular resin composition. If necessary, the resin composition may be crushed and then molded into tablets, or may be crushed and then molded into a sheet by, for example, vacuum lamination or compression molding.

[0062] <Molded Article / Cured Product> The molded article of this embodiment uses a cured product of the flame-retardant resin composition and is suitable for applications requiring flame retardancy. Specific examples include various structural components for transportation equipment such as cars, aircraft, railroad vehicles, and ships, buildings, office equipment, general-purpose machines, household electrical appliances, and electrical equipment. In particular, the molded article is suitable for use as an in-vehicle component. The cured product (complete curing) of the flame-retardant resin composition can be obtained, for example, by heating the flame-retardant resin composition at 165 to 175°C for 0.5 to 10 minutes.

[0063] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0064] The present invention will be described in detail based on examples and comparative examples, but the present invention is not limited to these examples.

[0065] (1) Raw materials for flame-retardant resin composition A flame-retardant resin composition was prepared using the following raw materials. [Raw materials] (Thermosetting resins) Phenolic resin 1: resol-type phenolic resin, "PR-53529" manufactured by Sumitomo Bakelite Co., Ltd. Diallyl isophthalate resin 1: Daiso Isodap manufactured by Osaka Soda Co., Ltd. Weight average molecular weight (polystyrene equivalent): 3 × 10 ４ ~5 x 10 ４ , iodine value: 75 to 90, softening point: 50°C to 80°C, and having a chemical structure represented by the following formula (1):

[0066]

[0067] Diallyl orthophthalate resin 1: Daiso DAP K, manufactured by Osaka Soda Co., Ltd., weight average molecular weight (polystyrene equivalent): 2 × 10 ４ ~3 x 10 ４ , iodine value: 50 to 60, softening point: 65°C to 100°C, and having a chemical structure represented by the following formula (2):

[0068]

[0069] Unsaturated polyester resin 1: Unsaturated polyester resin Teletype, 8523, manufactured by Japan U-Pica Co., Ltd. Unsaturated polyester resin 2: Unsaturated polyester resin Isotype, 8510, manufactured by Japan U-Pica Co., Ltd.

[0070] (Curing Agents) Curing Agent 1: Hexamethylenetetramine: "HEXAMINE" manufactured by CHANG CHUN PETROCHEMICAL. CO. LTD.

[0071] (Hardening aid) Hardening aid 1: Calcium hydroxide: "Slaked lime SA074" manufactured by Chichibu Lime Industry Co., Ltd.

[0072] (Polymerization initiator) Polymerization initiator 1: organic peroxide (thermal decomposition temperature (decomposition temperature for obtaining a half-life of 1 minute): 175°C)

[0073] (Monomers) Diallyl phthalate compound 1: manufactured by Osaka Soda Co., Ltd., product name: Daiso DAP 100 Monomer, having a chemical structure represented by the following formula (3)

[0074]

[0075] (Flame retardants) Organic flame retardant 1: aromatic condensed phosphate ester, "PX-200" manufactured by Daihachi Chemical Co., Ltd. Organic flame retardant 2: melamine polyphosphate, "MPP-A" manufactured by Sanwa Chemical Co., Ltd. Organic flame retardant 3: phenyl silicone resin, "RSN-6018" manufactured by Dow-Toray Industries, Inc. Organic flame retardant 4: methyl silicone resin, "SILRES (registered trademark) MK" manufactured by Wacker Asahi Kasei Silicone Co., Ltd. Inorganic flame retardant 5: aluminum hydroxide, C-308, manufactured by Sumitomo Chemical Co., Ltd., average particle size d ５０ Inorganic flame retardant 6: aluminum hydroxide, C-31, manufactured by Sumitomo Chemical Co., Ltd., average particle size d ５０ = 50 μm Organic / inorganic combined flame retardant 7: a mixture of ethylene bistetrabromophthalimide and antimony trioxide

[0076] (Inorganic fillers) Inorganic filler 1: glass fiber, "CS3E479" manufactured by Nitto Boseki Co., Ltd. Inorganic filler 2: clay, "SP33" manufactured by BASF South East Asia Pte Ltd. Inorganic filler 3: calcium carbonate, Tankal NS#100 manufactured by Nitto Funka Kogyo Co., Ltd.

[0077] (Additives) Additive 1 (mold release agent): calcium stearate "Ca-St" manufactured by Nitto Kasei Kogyo Co., Ltd. Additive 2 (pigment): carbon black "Carbon Black #750" manufactured by Mitsubishi Chemical Corporation

[0078] (2) Preparation of Flame-Retardant Resin Compositions <Examples 1 to 11, Comparative Examples 1 and 2> Each component was mixed at the compounding ratio (parts by mass) and roll rotation number (times) shown in Table 1 to prepare a flame-retardant resin composition.

[0079] (3) Measurement of Color Difference (i) Using each of the obtained flame-retardant resin compositions, test plates (120 mm square, 2 mm thick) were prepared under conditions of a mold temperature of 175°C and a curing time of 3 minutes. (ii) A torch burner (2.2 kW, "Power Torch RZ-720E" manufactured by Shinfuji Burner Co., Ltd.) was applied to the center of one side of the test plate, which was held vertically, at an angle of 90° to the test plate (30 mm for a flame length of approximately 100 mm), and the flame was applied for 5 minutes. (iii) The color difference before and after flame application was measured at the center of the other side of the test plate and at two points 3 mm from the center on a line passing through the center of the other side, and the average color difference (ΔEr) was calculated. (iv) Separately, the color difference between before and after exposure to flame was measured at the center of one side of the test plate obtained in step (ii) and at two points on a line passing through the center of the one side and 3 mm from the center, and the average value (ΔEf) was calculated. The color difference was measured using a "CR-241" manufactured by Konica Minolta, Inc.

[0080] (4) UL-94 Standard Test plates (size: 125 mm x 13 mm, thickness: 0.75 mm) were prepared using the flame-retardant resin composition under conditions of a mold temperature of 175°C and a curing time of 3 minutes, and tests were carried out in accordance with the UL-94 standard. The results are shown in Table 1.

[0081] (5) Evaluation Test plates (120 mm square, 2 mm thick) were prepared using the flame-retardant resin composition under conditions of a mold temperature of 175°C and a curing time of 3 minutes. A torch burner (Power Torch RZ-720E, 2.2 kW, manufactured by Shinfuji Burner Co., Ltd.) was applied to the center of one side (front surface) of the vertically positioned test plate at a 90° angle to the test plate (30 mm for a flame length of approximately 100 mm) and the test plate was exposed to flame for 5 minutes. The ashing area of ​​the test plate after exposure to flame was calculated, and the "flame retardancy" was evaluated according to the following criteria. Specifically, the front and back surfaces of the test plate were visually observed, and areas that turned grayish white were considered to have been ashed. The results are shown in Table 1. As representative examples showing the results of the flame retardancy evaluation of the test plates, photographs of the front and back surfaces of the test plates of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 are shown in Figures 1 to 4, respectively. In the photographs of Figures 1 to 4, some areas not related to the flame retardancy evaluation are masked. ○: No incineration. △: Incineration. Incineration area: 20 cm ２ Less than ×: Ashing occurred. Ashing area 20 cm ２ End

[0082]

[0083] This application claims priority based on Japanese Patent Application No. 2024-007884, filed January 23, 2024, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A flame-retardant resin composition containing a thermosetting resin and a flame retardant, wherein ΔEr obtained by the following procedure is 30 or less. Procedure: (i) Using the flame-retardant resin composition, a test plate (size 120 mm square, thickness 2 mm) is prepared under the conditions of a mold temperature of 175°C and a curing time of 3 minutes. (ii) A torch burner (30 mm with respect to a flame length of about 100 mm) is applied to the center of one surface of the vertically placed test plate so that the angle with respect to the test plate is 90°, and the test plate is exposed to the flame for 5 minutes. (iii) For the center of the other surface of the test plate and two points on a straight line passing through the center of the other surface and at a distance of 3 mm from the center, the color difference before and after the flame exposure is measured respectively, and the average value (ΔEr) is obtained.

2. The flame-retardant resin composition according to claim 1, wherein the flame retardant contains one or more selected from organic flame retardants and inorganic flame retardants.

3. The flame-retardant resin composition according to claim 1 or 2, further containing an inorganic filler.

4. The flame-retardant resin composition according to any one of claims 1 to 3, wherein when the color difference before and after the flame exposure is measured respectively for the center of one surface of the test plate obtained in (ii) of the above procedure and two points on a straight line passing through the center of the one surface and at a distance of 3 mm from the center, and the average value (ΔEf) is obtained, ΔEf is 0 to 100.

5. The flame-retardant resin composition according to any one of claims 1 to 4, wherein the content of the flame retardant is 1 to 45 parts by mass with respect to 100 parts by mass of the flame-retardant resin composition.

6. The flame-retardant resin composition according to any one of claims 1 to 5, wherein the thermosetting resin contains one or more selected from phenol resins, diallyl phthalate resins, unsaturated polyester resins, epoxy resins, melamine resins, and furan resins.

7. The flame-retardant resin composition according to claim 3, wherein the inorganic filler is one or more selected from fiber fillers, plate-like fillers, and spherical fillers.

8. The flame-retardant resin composition according to claim 3 or 7, wherein the inorganic filler is one or more selected from glass fiber, carbon fiber, metal fiber, and mineral filler.

9. The flame-retardant resin composition according to claim 3 or 7 or 8, wherein the content of the inorganic filler is 30 to 85 parts by mass with respect to 100 parts by mass of the flame-retardant resin composition.

10. The flame-retardant resin composition according to any one of claims 1 to 9, wherein a test plate (size: 125 mm × 13 mm, thickness: 0.75 mm) is prepared under the conditions of a mold temperature of 175 ° C and a curing time of 3 minutes using the flame-retardant resin composition, and in a test conforming to the UL-94 standard, it satisfies V-1 of the UL-94 standard.

11. The flame-retardant resin composition according to any one of claims 1 to 10, which is used for in-vehicle parts.

12. A cured product of the flame-retardant resin composition according to any one of claims 1 to 10.

13. An in-vehicle part comprising a cured product of the flame-retardant resin composition according to claim 11.

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