Resin compositions, molded articles, electronic devices and electrical equipment

Abstract

The present invention relates to a resin composition, a molded article, an electronic device, and an electrical device. The resin composition of the present invention is a resin composition comprising a polyolefin, a metal salt of a dialkylphosphinic acid, and a monoalkylphosphinic acid, wherein the proportion of the metal salt of the dialkylphosphinic acid with respect to the resin composition is 1 mass% or more and 20 mass% or less, and the proportion of the monoalkylphosphinic acid with respect to the metal salt of the dialkylphosphinic acid is 1 mass% or more and 20 mass% or less.

Description

Technical Field

[0001] This invention relates to resin compositions, molded articles using the resin compositions, electronic devices and electrical equipment having the molded articles. Background Technology

[0002] Molded articles made of resin compositions are sometimes used as interior and exterior materials for electronic devices, including photocopiers. Examples of thermoplastic resins contained in such resin compositions include polyolefin resins.

[0003] To improve the flame retardancy of resin compositions containing polyolefin resins, various flame retardants such as halogenated, phosphorus-based, and metal hydrates are considered.

[0004] For example, Patent Document 1 discloses a flame-retardant resin composition in which a specific amount of a flame retardant consisting of silicone oil, polysiloxane resin and a phosphorus-nitrogen compound (ammonium polyphosphate) is added to polypropylene.

[0005] Patent document 2 discloses a flame-retardant resin composition in which a specific amount of phenolic resin, phosphorus-containing compound (red phosphorus) and expandable graphite are incorporated into a polyolefin resin.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 64-14277

[0009] Patent Document 2: Japanese Patent Application Publication No. 9-111059 Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] Compared to polycarbonate and ABS resins, such polyolefin resins have weaker intermolecular forces in their chemical structure and are more prone to rotation through single bonds, resulting in poor flame retardancy. To improve the flame retardancy of polyolefin resins, large amounts of flame retardants are usually required; however, excessive use of flame retardants leads to a decrease in strength.

[0012] The object of the present invention is to provide a resin composition capable of suppressing the reduction of flame retardancy and strength, a molded article formed from the resin composition, an electronic device having the molded article, and an electrical device having the molded article.

[0013] Technical means to solve technical problems

[0014] This invention relates to the following resin compositions, molded articles, electronic devices, and electrical devices.

[0015] [1] A resin composition comprising a polyolefin, a dialkylphosphine metal salt and a monoalkylphosphine, wherein the dialkylphosphine metal salt is present in a proportion of 1% by mass or more and 20% by mass or less relative to the resin composition, and the monoalkylphosphine is present in a proportion of 1% by mass or more and 20% by mass or less relative to the dialkylphosphine metal salt.

[0016] [2] According to the resin composition of [1], wherein the proportion of the dialkylphosphino acid metal salt to the resin composition is more than 2% by mass and less than 5% by mass.

[0017] [3] The resin composition according to [1] or [2], wherein the ratio of the monoalkylphosphino acid to the dialkylphosphino acid metal salt is 5% by mass or more and 20% by mass or less.

[0018] [4] The resin composition according to any one of [1] to [3], wherein the polyolefin is polypropylene.

[0019] [5] The resin composition according to any one of [1] to [4], wherein the dialkylphosphine metal salt is aluminum diethylphosphine.

[0020] [6] The resin composition according to any one of [1] to [5], wherein the monoalkylphosphine is monoethylphosphine.

[0021] [7] A molded article formed from any one of the resin compositions described in [1] to [6].

[0022] [8] An electronic device having the molded article described in [7].

[0023] [9] An electrical device having the molded article described in [7].

[0024] Invention Effects

[0025] According to the present invention, a resin composition capable of suppressing the reduction of flame retardancy and strength can be provided, a molded article formed from the resin composition, an electronic device having the molded article, and an electrical device having the molded article. Detailed Implementation

[0026] The resin composition of the embodiments of the present invention is a resin composition comprising a polyolefin, a dialkylphosphine metal salt and a monoalkylphosphine, wherein the proportion of the dialkylphosphine metal salt to the resin composition is 1% or more by mass and 20% or less by mass, and the proportion of the monoalkylphosphine to the dialkylphosphine metal salt is 1% or more by mass and 20% or less by mass.

[0027] The reasons for suppressing the reduction in flame retardancy and strength of molded articles formed from this resin composition are speculated as follows.

[0028] Dialkylphosphonic acid metal salts are particulate flame retardants that do not decompose at the high temperatures (approximately 300°C) during compounding and molding. That is, in molded articles formed from this resin composition, the dialkylphosphonic acid metal salt exists in particulate form. Generally, the higher the amount of flame retardant, the better the flame retardancy; however, the presence of large amounts of particulate flame retardants such as dialkylphosphonic acid metal salts in the molded article reduces the strength of the molded article.

[0029] In the resin composition of this embodiment, in addition to the dialkylphosphine metal salt, a monoalkylphosphine acid is also included as a flame retardant. Therefore, both flame retardancy and strength can be achieved. The mechanism is not necessarily clear, but it is speculated as follows.

[0030] It is known that low molecular weight compounds typically aggregate near the surface of molded articles during molding, and it is believed that low molecular weight monoalkylphosphine acids also aggregate near the surface of molded articles. Here, the mechanism by which flame retardants exhibit flame retardancy is considered to be a free radical scavenging effect in the gas phase, and it is believed that the monoalkylphosphine acids aggregated near the surface of the molded article promote this free radical scavenging effect. Thus, it is believed that by appropriately including monoalkylphosphine acids in a resin composition containing dialkylphosphine metal salts, even if the amount of dialkylphosphine metal salts is less than 20% by mass relative to the resin composition, a decrease in flame retardancy and a decrease in strength can be suppressed.

[0031] As mentioned above, a higher proportion of monoalkylphosphonic acid (MSA) is more effective in suppressing the reduction in strength and flame retardancy. However, when the proportion of MSA relative to dialkylphosphonic acid metal salt is excessive, flame retardancy decreases. Although the mechanism is not necessarily clear, it is believed that an excessive amount of MSA decomposes the dialkylphosphonic acid metal salt. Therefore, it is considered preferable to have an MSA to dialkylphosphonic acid metal salt ratio of 1% by mass or more and 20% by mass or less.

[0032] The following describes the polyolefin, dialkylphosphine metal salt, and monoalkylphosphine contained in the resin composition of this embodiment. Furthermore, other components that may be included in the resin composition of this embodiment will also be described.

[0033] (Polyolefins)

[0034] Polyolefins serve as the base material for the resin composition. Any homopolymer or copolymer polymerized with olefins as the main monomer component is acceptable. Here, "olefin" simply refers to an aliphatic chain unsaturated hydrocarbon having one double bond.

[0035] Polyolefins include copolymers of olefins with other olefins, or copolymers of olefins with other monomers that can be copolymerized with olefins.

[0036] The preferred olefins are α-olefins with 2 to 12 carbon atoms. Examples of α-olefins include ethylene, propylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 1-octene, 1-decene, and 1-dodecene. One olefin may be used alone, or two or more may be used in combination.

[0037] Examples of other monomers that can copolymerize with α-olefins include cyclic olefins such as cyclopentene and norbornene, and dienes such as 1,4-hexadiene and 5-ethylidene-2-norbornene. Other examples include vinyl acetate, styrene, (meth)acrylic acid and its derivatives, vinyl ethers, maleic anhydride, carbon monoxide, and N-vinylcarbazole. Other monomers can be used alone or in combination of two or more in the polymerization of polyolefins. It should be noted that "(meth)acrylic acid" refers to at least one of acrylic acid and methacrylic acid.

[0038] Examples of polyolefins include: polyethylenes with ethylene as the main component, such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE); polypropylene resins with propylene as the main component, such as polypropylene (propylene homopolymer), ethylene-propylene copolymer, propylene-butene copolymer, ethylene-propylene-butene copolymer, and ethylene-propylene-diene copolymer; polybutene; and polypentene.

[0039] Examples of polyolefin resins also include ethylene-vinyl acetate copolymers (EVA), ethylene-ethyl acrylate copolymers, polyketides, and copolymers produced using metallocene catalysts. Furthermore, substances obtained by chemically reacting and modifying these polymers are also included, specifically ionomer resins, saponifications of EVA, and olefin elastomers produced by dynamic vulcanization in an extruder.

[0040] Polyolefin resins are preferably polyethylene resins and polypropylene resins, with polypropylene resins being more preferred. The stereoregularity of the propylene-derived structure in the polypropylene resin can be any of isotactic, syndiotactic, and atactic.

[0041] Examples of commercially available polyolefins include the various series of polypropylene resins "PRIMEPOLYPRO", "POLYFINE", and "PRIME TPO" manufactured by PRIME POLYMER (e.g., PRIME POL YPRO J715M) and the various series of polyethylene resins "HI-ZEX", "NEO-ZEX", "ULT-ZEX", "MORETEC", and "EVOLUE" manufactured by PRIME POLYMER (e.g., HI-ZEX 1300J).

[0042] From the perspective of easily improving the strength and heat resistance of the molded product, polyolefins are preferred, and propylene homopolymers are even more preferred.

[0043] The proportion of polyolefin relative to the resin composition is in the range of 29.0% by mass or more and 98.0% by mass or less, preferably in the range of 50% by mass or more and 93.95% by mass or less. When the proportion of polyolefin relative to the resin composition is 29.0% by mass or more, the properties of polyolefin are more easily and fully obtained, and when it is 93.95% by mass or less, the strength of the molded article is more easily improved.

[0044] There are no particularly limited methods for detecting polyolefins. Polyolefins can be detected using well-known methods. For example, polyolefins can be detected by combining IR (infrared spectroscopy), DSC (differential scanning calorimetry), and NMR (nuclear magnetic resonance spectroscopy). Specifically, for example, the resin composition or molded article can be cryogenically pulverized, and the dissolved substances in chloroform can be determined and detected using NMR.

[0045] (Dialkylphosphine metal salt)

[0046] Dialkylphosphonic acid metal salts function as flame retardants. Dialkylphosphonic acid metal salts may comprise compounds that can be represented by the following formula.

[0047] [Chemical Formula 1]

[0048]

[0049] R 1 and R 2 Each alkyl group can be independently defined as having 1 to 8 carbon atoms. n and m can each take values ​​from 1 to 3. M can be a metal. Examples of metals include metals that can become cations. Examples of metals include alkali metals, alkaline earth metals, aluminum, etc.

[0050] Dialkylphosphine metal salts are preferred from R 1 and R 2 Aluminum diethylphosphinate with ethyl group and M being aluminum.

[0051] From the viewpoint of improving flame retardancy, the proportion of dialkylphosphine metal salt to the resin composition is preferably 1% by mass or more, more preferably 2% by mass or more, more preferably 5% by mass or more, more preferably 7% by mass or more, more preferably 10% by mass or more, and more preferably 15% by mass or more. On the other hand, from the viewpoint of improving strength, the proportion of dialkylphosphine metal salt to the resin composition is preferably 20% by mass or less, more preferably 15% by mass or less, more preferably 10% by mass or less, and more preferably 5% by mass or less. From the viewpoint of balancing flame retardancy and strength, the proportion of dialkylphosphine metal salt to the resin composition is preferably 1% by mass or more and 20% by mass or less, more preferably 2% by mass or more and 5% by mass or less.

[0052] There are no particular limitations on the detection methods for dialkylphosphonic acid metal salts. Dialkylphosphonic acid metal salts can be detected using well-known methods. For example, they can be detected by combined ion chromatography, capillary electrophoresis, ICP-AES (inductively coupled plasma atomic emission spectrometry), ICP-MS (inductively coupled plasma mass spectrometry), atomic absorption spectrometry, fluorescence X-ray diffraction, NMR, etc. Specifically, for example, the resin composition or molded article can be cryogenically pulverized, and the dissolved substances in chloroform can be determined and detected using NMR.

[0053] (Monoalkylphosphonic acid)

[0054] Monoalkyl phosphonates function as flame retardants. It is speculated that monoalkyl phosphonates readily exist near the surface of molded articles, effectively exhibiting free radical scavenging effects in the gas phase and thus exerting flame retardant properties. Monoalkyl phosphonates may comprise compounds that can be represented by the following formula.

[0055] [Chemical Formula 2]

[0056]

[0057] R can be an alkyl group having 1 to 8 carbon atoms. Monoalkyl phosphonic acid is preferably monoethyl phosphonic acid in which R is an ethyl group.

[0058] The content of monoalkylphosphine in the resin composition is preferably adjusted in proportion to the dialkylphosphine metal salt. Specifically, the proportion of monoalkylphosphine to the dialkylphosphine metal salt is preferably 20% by mass or less. The proportion of monoalkylphosphine to the dialkylphosphine metal salt is preferably 1% by mass or more, and more preferably 5% by mass or more. The proportion of monoalkylphosphine to the dialkylphosphine metal salt is preferably set to 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 20% by mass or less. When the proportion of monoalkylphosphine to the dialkylphosphine metal salt is less than 1% by mass, the flame retardancy decreases. Furthermore, even when the proportion of monoalkylphosphine to the dialkylphosphine metal salt is 20% by mass or more, the flame retardancy also decreases. This is presumably because, under the heating condition during the mixing of the resin composition, the dialkylphosphine metal salt reacts with the monoalkylphosphine, and the dialkylphosphine metal salt is decomposed.

[0059] It should be noted that the proportion of monoalkylphosphino acid relative to the resin composition is, for example, 0.1% by mass or more and 3% by mass or less.

[0060] There are no particularly limited methods for detecting monoalkylphosphonic acids. Monoalkylphosphonic acids can be detected using well-known methods. For example, they can be detected by combining ion chromatography, capillary electrophoresis, ICP-AES (inductively coupled plasma atomic emission spectrometry), ICP-MS (inductively coupled plasma mass spectrometry), atomic absorption spectrometry, fluorescence X-ray diffraction, and NMR. Specifically, for example, the resin composition or molded article can be cryogenically pulverized, and the dissolved substances in chloroform can be determined and detected using NMR.

[0061] (Other ingredients)

[0062] The resin composition may contain other components without impairing the effects of the present invention. Examples of other components include flame retardants other than the flame retardant described above, fillers, impact modifiers, nucleating agents, antioxidants, light stabilizers, antistatic agents, lubricants, plasticizers, pigments, dyes, etc. Furthermore, the resin composition may contain components known as additives. These will be described separately below.

[0063] <Other flame retardants>

[0064] Other examples of flame retardants include phosphorus-based flame retardants such as phosphate esters, ammonium polyphosphate, and guanidine phosphate; nitrogen-based flame retardants such as melamine cyanurate and guanidine compounds; and polysiloxane-based flame retardants. Other flame retardants can be used alone or in combination of two or more.

[0065] <filler>

[0066] Fillers are broadly classified into organic fillers and inorganic fillers. Examples of organic fillers include naturally derived polymers such as starch, cellulose microparticles, cellulose fibers, wood flour, tofu residue, rice husks, and wheat bran, as well as their modified forms. In addition, high-melting-point organic fibrous materials such as polyamides, fluoropolymers, and acrylic resins can also be used.

[0067] As inorganic fillers, fibrous, granular, or plate-like fillers can be used. Examples of fibrous fillers include glass fibers, carbon fibers, silica fibers, silica-alumina fibers, zirconium oxide fibers, boron nitride fibers, silicon nitride fibers, boron fibers, potassium titanate fibers, wollastonite, barium sulfate fibers, and fibrous materials of metals such as stainless steel, aluminum, titanium, copper, and brass.

[0068] Examples of granular fillers include carbon black, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, oxides of metals such as iron oxide, titanium oxide, and aluminum oxide, carbonates of metals such as calcium carbonate and magnesium carbonate, sulfates of metals such as calcium sulfate and barium sulfate, as well as silicon carbide, silicon nitride, boron nitride, and various metal powders. Examples of plate-like inorganic fillers include mica, glass flakes, layered silicates, and various metal foils. A single filler can be used, or two or more can be used in combination.

[0069] Impact Modifier

[0070] The impact modifier is preferably a thermoplastic elastomer, such as ethylene propylene diene monomer (EPDM), which is mainly composed of olefin-derived units. Alternatively, the impact modifier may also be a thermoplastic elastomer, but it is particularly preferred to include olefin-derived units. Examples of thermoplastic elastomers include methyl methacrylate-butadiene-styrene copolymer (MBS), acrylonitrile-butadiene-styrene copolymer (ABS), styrene-butadiene-styrene copolymer (SBS), styrene-ethylene-butene-styrene block copolymer (SEBS), ethylene-octene copolymer (EOR), and butyl acrylate-methyl methacrylate copolymer. From the viewpoints of compatibility and flame retardancy of the resin composition, and the dispersibility of the thermoplastic elastomer in the resin composition, SEBS and EOR are preferred impact modifiers. One impact modifier may be used alone, or two or more may be used in combination.

[0071] <Crystallization nucleating agent>

[0072] Known nucleating agents can be used for crystallization. Examples of nucleating agents include metal salts of carboxylic acids, dibenzylsorbitol derivatives, and alkali metal salts of phosphoric acids. Specific examples of nucleating agents include: sodium benzoate, aluminum adipic acid, aluminum p-tert-butylbenzoate, 1,3,2,4-dibenzylsorbitol, 1,3,2,4-bis(p-methylbenzyl)sorbitol, 1,3,2,4-bis(p-ethylbenzyl)sorbitol, 1,3-p-chlorobenzyl-2,4-p-methylbenzyl)sorbitol, sodium bis(4-tert-butylphenyl)phosphate, sodium bis(4-tert-methylphenyl)phosphate, potassium bis(4,6-di-tert-butylphenyl)phosphate, sodium 2,2'-methylene-bis(4,6-di-tert-butylphenyl)phosphate, and sodium 2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)phosphate. A single nucleating agent can be used alone, or two or more can be used in combination.

[0073] Antioxidants

[0074] Examples of antioxidants include phenolic antioxidants, phosphorus antioxidants, and sulfur antioxidants. Phenolic antioxidants are preferred, and alkyl-substituted phenolic antioxidants are more preferred. Antioxidants can be used alone or in combination of two or more.

[0075] Light stabilizer

[0076] Examples of light stabilizers include benzophenone-based light stabilizers, benzotriazole-based light stabilizers, and hindered amine-based light stabilizers of the NH and N-methyl types. A single light stabilizer can be used alone, or two or more can be used in combination.

[0077] Antistatic agent

[0078] Examples of antistatic agents include: cationic antistatic agents such as fatty acid quaternary ammonium salts and polyamine quaternary salts; anionic antistatic agents such as higher alcohol phosphate salts, higher alcohol EO adducts, polyethylene glycol fatty acid esters, anionic alkyl sulfonates, higher alcohol sulfate salts, higher alcohol ethylene oxide adduct sulfate salts, and higher alcohol ethylene oxide adduct phosphate salts; nonionic antistatic agents such as polyol fatty acid esters, polyethylene glycol phosphate esters, and polyoxyethylene alkyl allyl ethers; and amphoteric antistatic agents such as alkyl betaine (e.g., alkyl dimethylaminoacetic acid betaine) and imidazoline amphoteric surfactants. Antistatic agents can be used alone or in combination of two or more.

[0079] Lubricant

[0080] Examples of lubricants include fatty acid salts, fatty acid amides, silane polymers, solid paraffin, liquid paraffin, magnesium stearate, calcium stearate, zinc stearate, stearamide, polysiloxane powder, methylene bis-stearamide, and N,N'-ethylene bis-stearamide. A lubricant can be used alone or in combination of two or more.

[0081] <Plasticizer>

[0082] Examples of plasticizers include polyethylene glycol, polyamide oligomers, ethylene bis-stearamide, phthalates, adipates, polystyrene oligomers, polyethylene wax, silicone oil, and mineral oil. Plasticizers can be used alone or in combination of two or more.

[0083] The content of other additives in the resin composition of the present invention is within a range that does not impair the effects of the present invention, for example, in the range of about 0.1 to 30% by mass relative to the total mass of the resin composition, preferably in the range of 0.1 to 20% by mass.

[0084] There are no particular limitations on the method of manufacturing the resin composition. For example, the resin composition can be manufactured by mixing and melt-kneading the components.

[0085] In this embodiment, melt mixing is performed using mixing equipment such as a Banbury mixer, rollers, a plastograph, an extruder (single-screw extruder, multi-screw extruder (e.g., twin-screw extruder)), and a kneader. From the viewpoint of production efficiency, melt mixing is preferably performed using an extruder. Furthermore, from the viewpoint of imparting high shear strength, melt mixing is more preferably performed using a multi-screw extruder, and particularly preferably using a twin-screw extruder. Here, the term "extruder" is used within the scope that includes extrusion mixing machines.

[0086] The melt mixing temperature is above the melting temperature of the polyolefin resin. The preferred melt mixing temperature is 150–250°C, selected appropriately based on the polyolefin resin used. When using polypropylene resin as the polyolefin resin, the preferred melt mixing temperature is 160–220°C. When using an extruder in melt mixing, the mixing melt temperature is equivalent to the barrel temperature.

[0087] It should be noted that before melt mixing, the components can be premixed (dry mixing) using various mixers such as drum mixers and high-speed mixers known as Henschel mixers.

[0088] In the manufacturing method of this embodiment, after the molten compound is extruded into a strand, the extruded compound can be processed into pellets, flakes, or other shapes.

[0089] It should be noted that the resin composition of the present invention can be in various forms such as powder, granules, tablets, pellets, and thin sheets.

[0090] The resin composition in the embodiments is molded into any shape to form a molded article. Examples of molding methods for the molded article include injection molding, extrusion molding, blow molding, vacuum molding, profile extrusion molding, compression molding, and gas-assisted molding.

[0091] When manufacturing injection-molded articles using the resin composition of this embodiment, conventionally known injection molding machines can be used. Injection-molded articles are manufactured by melting the resin composition in a barrel, injecting the molten resin composition into a mold, and allowing it to cool and solidify. The injection speed and pressure are appropriately adjusted. Preferred injection molding conditions are, for example, a barrel temperature (melt temperature) of 170–230°C and a mold temperature of 40–80°C.

[0092] There are no particular restrictions on the shape and size of the molded product; it can be set arbitrarily according to the intended use of the product.

[0093] Molded parts can be used as internal or external components for electrical or electronic equipment such as home appliances, office automation and media-related equipment, optical equipment, and communication equipment; automotive parts; mechanical parts; and residential and building components. From the perspective of excellent strength, good flame retardancy, and low environmental impact, molded parts are suitable for use as external components (especially housings) for electrical or electronic equipment such as copiers, printers, personal computers, and televisions.

[0094] [Example]

[0095] The present invention will now be described in detail with reference to embodiments, but the present invention is not limited to these embodiments.

[0096] [Example 1]

[0097] Using a KTX-30 (manufactured by Kobe Steel) as a twin-screw mixer, the resin composition of Example 1 was obtained by melt mixing with 94.2% by mass of polypropylene (“J715M” (manufactured by PRIME POLYMER) as resin, 5% by mass of aluminum diethylphosphonate (“Exolit OP1230” (manufactured by CLARIANT) as flame retardant, and 0.8% by mass of monoethylphosphonic acid (“JAMP-2”, manufactured by Jōhoku Chemical Industry Co., Ltd.) at a barrel temperature of 190°C and a screw speed of 200 rpm.

[0098] [Example 2]

[0099] Except that the polypropylene was 96.0% by mass, the aluminum diethylphosphonate was 3.5% by mass, and the monoethylphosphonic acid was 0.5% by mass, the resin composition of Example 2 was obtained in the same manner as in Example 1.

[0100] [Example 3]

[0101] Except that the polypropylene was 97.7% by mass, the aluminum diethylphosphinate was 2.0% by mass, and the monoethylphosphinate was 0.3% by mass, the resin composition of Example 3 was obtained in the same manner as in Example 1.

[0102] [Example 4]

[0103] Except that the polypropylene content was 80.5% by mass, the aluminum diethylphosphonate content was 17.5% by mass, and the monoethylphosphonic acid content was 2.0% by mass, the resin composition of Example 4 was obtained in the same manner as in Example 1.

[0104] [Example 5]

[0105] Except that the polypropylene content was 86.5% by mass, the aluminum diethylphosphonate content was 12.5% ​​by mass, and the monoethylphosphonic acid content was 1.0% by mass, the resin composition of Example 5 was obtained in the same manner as in Example 1.

[0106] [Example 6]

[0107] Except that the polypropylene content was 91.8% by mass, the aluminum diethylphosphinate content was 8.0% by mass, and the monoethylphosphinate content was 0.2% by mass, the resin composition of Example 6 was obtained in the same manner as in Example 1.

[0108] [Comparative Example 1]

[0109] Except that the polypropylene content was 74.9% by mass, the aluminum diethylphosphonate content was 25.0% by mass, and the monoethylphosphonic acid content was 0.1% by mass, the resin composition of Comparative Example 1 was obtained in the same manner as in Example 1.

[0110] [Comparative Example 2]

[0111] Except that the polypropylene was 99.4% by mass, the aluminum diethylphosphonate was 0.5% by mass, and the monoethylphosphonic acid was 0.1% by mass, the resin composition of Comparative Example 2 was obtained in the same manner as in Example 1.

[0112] [Comparative Example 3]

[0113] Except that the polypropylene content was 93.5% by mass, the aluminum diethylphosphinate content was 4.5% by mass, and the monoethylphosphinate content was 2.0% by mass, the resin composition of Comparative Example 3 was obtained in the same manner as in Example 1.

[0114] [Comparative Example 4]

[0115] Except that the polypropylene content was 96.0% by mass, the triphenylphosphine content was 3.5% by mass, and the monoethylphosphonic acid content was 0.5% by mass, the resin composition of Comparative Example 4 was obtained in the same manner as in Example 1.

[0116] [Comparative Example 5]

[0117] Except that the polypropylene content was 97.7% by mass, the aluminum diethylphosphinate content was 2.0% by mass, and the tricresyl phosphate content was 0.3% by mass, the resin composition of Comparative Example 5 was obtained in the same manner as in Example 1.

[0118] Table 1 below shows the composition of the resin compositions of Examples 1 to Comparative Examples 5.

[0119] [Table 1]

[0120]

[0121] [evaluate]

[0122] Flame retardancy and strength tests were conducted on the resin compositions of Examples 1-6 and Comparative Examples 1-5 obtained as described above.

[0123] (1) Flame retardancy test

[0124] After drying the resin compositions of each embodiment and each comparative example at 80°C for 4 hours, they were molded into strip-shaped test pieces with a length of 120 mm, a width of 10 mm, and a thickness of 1.6 mm using an injection molding machine (ROBOSHOT S-2000i50Bp, FANUC Corporation) at a barrel temperature of 170-200°C and a mold temperature of 80°C, and flame retardancy tests were conducted.

[0125] The flame retardancy test was conducted as follows: The test piece was conditioned for 48 hours in a constant temperature chamber at 23°C and 50% humidity, and then stored in a constant temperature chamber at 70°C for 168 hours. The flame was then tested according to the well-known UL94 (UL94 Flame Evaluation Method) provided by Underwriters Laboratories (UL). It should be noted that in this method, the burning time (until the flame disappears) after the flame comes into contact with the test piece is measured, with the flame contacted twice. In Table 2, burning times t1 and t2 represent the first and second burning times, respectively.

[0126] The test pieces of each embodiment and comparative example were evaluated, and the evaluation results are classified as follows.

[0127] ◎: V2 and the average burn time for the first and second burns is less than 10 seconds.

[0128] ○: V2 and the first burn time is more than 10 seconds but less than 20 seconds

[0129] △: V2 and burn time is more than 20 seconds but less than 30 seconds

[0130] ×: not V (burning time exceeds 30 seconds) (failed)

[0131] (2) Strength test (Charpy impact test)

[0132] After drying the resin composition particles of each embodiment and comparative example at 80°C for 4 hours, Charpy impact strength evaluation test pieces (80 mm in total length, 10 mm in width, 4 mm in thickness, and 8 mm in notch width) were molded using an injection molding machine (ROBOSHOT S-2000i50Bp, FANUC Corporation) under conditions of barrel temperature 170–200°C and mold temperature 80°C. The Charpy impact strength of the obtained test pieces was determined according to ISO 179. The Charpy impact strength of 10 test pieces was measured, and their arithmetic mean was calculated. The following evaluation criteria are marked with "◎" or "○" for passing and "×" for failing.

[0133] Evaluation Criteria

[0134] ◎: 15kJ / m 2 above

[0135] ○: 10kJ / m 2 Above and below 15 kJ / m 2

[0136] ×: Less than 10kJ / m 2

[0137] The evaluation results are shown in Table 2 below.

[0138] [Table 2]

[0139]

[0140] As shown in Tables 1 and 2, the reduction in flame retardancy and strength was suppressed in Examples 1 to 6. This is because, in Examples 1 to 6, the proportion of dialkylphosphine metal salt to the resin composition was 1% by mass or more and 20% by mass or less, and the proportion of monoalkylphosphine to dialkylphosphine metal salt was 1% by mass or more and 20% by mass or less.

[0141] Comparing Example 2 in Table 1 with Comparative Example 4, Example 2 contains both aluminum diethylphosphonate and monoethylphosphonic acid, while Comparative Example 4 contains monoethylphosphonic acid but not aluminum diethylphosphonate, instead containing triphenylphosphine. As shown in Table 2, Comparative Example 4 exhibits low flame retardancy and strength, while Example 2 demonstrates high flame retardancy and strength. Thus, when the resin composition contains both aluminum diethylphosphonate and monoethylphosphonic acid, both flame retardancy and strength can be improved.

[0142] Comparing Example 3 in Table 1 with Comparative Example 5, Example 3 contains both aluminum diethylphosphonate and monoethylphosphonic acid, while Comparative Example 5 contains aluminum diethylphosphonate but not monoethylphosphonic acid, instead containing tricresyl phosphate. As shown in Table 2, Comparative Example 5 exhibits low flame retardancy and strength, while Example 3 demonstrates high flame retardancy and strength. Thus, when the resin composition contains both aluminum diethylphosphonate and monoethylphosphonic acid, both flame retardancy and strength can be improved.

[0143] As demonstrated in Examples 2, 3, and Comparative Examples 4 and 5, the resin composition containing both aluminum diethylphosphonate and monoethylphosphonic acid improves flame retardancy and strength. This is presumably because there is some interaction between aluminum diethylphosphonate and monoethylphosphonic acid that enhances flame retardancy and strength. Specifically, as described above, it is presumed that the low-molecular-weight monoethylphosphonic acid aggregates near the surface of the molded article, promoting free radical capture in the gas phase.

[0144] Although Comparative Example 1 contains aluminum diethylphosphonate and monoethylphosphonic acid, the strength is reduced. This is because, in Comparative Example 1, the proportion of aluminum diethylphosphonate relative to the resin composition is as high as 25% by mass.

[0145] Although Comparative Example 2 contains aluminum diethylphosphonate and monoethylphosphonic acid, its flame retardancy is reduced. This is because, in Comparative Example 2, the proportion of aluminum diethylphosphonate relative to the resin composition is as low as 0.5% by mass.

[0146] Comparing Example 1 with Comparative Example 3, although both contain aluminum diethylphosphonic acid and monoethylphosphonic acid, the flame retardancy was reduced in Comparative Example 3. This is presumably because, in Comparative Example 3, the proportion of monoethylphosphonic acid relative to the metal salt of diethylphosphonic acid was as high as 20% or more, and aluminum diethylphosphonic acid was decomposed by monoethylphosphonic acid.

[0147] Furthermore, the strength of Examples 1-3, in which the proportion of aluminum diethylphosphonate is 2% or more and 5% or less, is higher than that of Examples 4-6, in which the proportion of aluminum diethylphosphonate exceeds 5% by mass.

[0148] Industrial applicability

[0149] The resin composition of the present invention is useful for molding parts that require flame retardancy and strength.

Claims

1. A resin composition comprising a polyolefin, a metal salt of a dialkylphosphinic acid, and a monoalkylphosphinic acid, wherein the proportion of the metal salt of the dialkylphosphinic acid with respect to the resin composition is 1 mass% or more and 20 mass% or less, and the proportion of the monoalkylphosphinic acid with respect to the metal salt of the dialkylphosphinic acid is 1 mass% or more and 20 mass% or less.

2. The resin composition according to claim 1, wherein the proportion of the metal salt of the dialkylphosphinic acid with respect to the resin composition is 2 mass% or more and 5 mass% or less.

3. The resin composition according to claim 1 or 2, wherein the proportion of the monoalkylphosphinic acid with respect to the metal salt of the dialkylphosphinic acid is 5 mass% or more and 20 mass% or less.

4. The resin composition according to claim 1 or 2, wherein the polyolefin is polypropylene.

5. The resin composition according to claim 1 or 2, wherein the metal salt of the dialkylphosphinic acid is aluminum diethylphosphinate.

6. The resin composition according to claim 1 or 2, wherein the monoalkylphosphinic acid is monoethylphosphinic acid.

7. A molded article molded from the resin composition according to any one of claims 1 to 6.

8. An electronic device having the molded article according to claim 7.

9. An electrical device having the molded article according to claim 7. ​ ​ ​ ​ ​ ​ ​

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