Flame-retardant polypropylene resin composition

Abstract

To provide a flame-retardant resin composition which has good flame retardancy, prevents occurrence of blooming and is excellent in heat resistance.SOLUTION: A flame-retardant polypropylene-based resin composition contains (A) 100 pts.wt. of a polypropylene-based resin, (B) 2-50 pts.wt. of a mixture of a specific bisphenol S derivative, (C) 0.2-20 pts.wt. of at least one of (C1) tetrabromobisphenol A bis(2,3-dibromopropyl)ether and (C2) tris(2,3-dibromopropyl)isocyanurate, and (D) 1-20 pts.wt. of at least one of antimony trioxide, antimony pentoxide, zinc molybdate, boron trioxide and zinc borate.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a novel flame-retardant polypropylene resin composition. [Background technology]

[0002] Polyolefins such as polypropylene are light, strong, and have good water resistance, chemical resistance, electrical insulation, etc., and are also easily molded, and therefore are widely used in a wide range of applications, such as building materials, electrical equipment materials, vehicle parts, automotive interior materials, wire coating materials, and various industrial and household products. However, polyolefins have the drawback of being easily flammable. For this reason, many methods have been proposed for making polyolefins flame retardant.

[0003] As a method for making resin flame-retardant, a method of blending a flame retardant with resin has been adopted for some time. For example, there is a flame retardant containing a bromine compound and an antimony compound, and as the bromine compound, a brominated bisphenol S derivative is known to have high flame retardancy. For this reason, various resin compositions blended with these flame retardants have been proposed.

[0004] For example, a flame-retardant polyolefin resin composition having a ratio of (A) 70 to 98% by weight of a polyolefin resin and (B) 2 to 30% by weight of a bromine-containing flame retardant, and containing a specific compound as the bromine-containing flame retardant, is disclosed (Patent Document 1). Patent Document 1 also describes that antimony trioxide may be used in combination with the bromine-containing flame retardant as a flame retardant aid (Patent Document 1).

[0005] Also, for example, a polypropylene resin composition is known that contains a polypropylene resin (A) that satisfies specific conditions, a filler (B), a halogen-based flame retardant (C) that satisfies specific conditions, and a flame retardant auxiliary (E) (Patent Document 2).

[0006] While these flame-retardant resin compositions provide a certain degree of flame retardancy, they are prone to a phenomenon known as blooming, in which the flame retardant seeps out onto the resin surface and turns white when the polyolefin resin is kneaded with the flame retardant or the like or after the kneading (including after molding).

[0007] Therefore, the present inventors have previously proposed a brominated flame retardant containing a brominated bisphenol S derivative in order to develop a flame retardant capable of suppressing blooming (Patent Document 3). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2004-99780 A [Patent Document 2] JP 2015-78276 A [Patent Document 3] Patent No. 4817726 Summary of the Invention [Problem to be solved by the invention]

[0009] However, although the brominated flame retardant as shown in Patent Document 3 has an excellent effect of suppressing blooming, there is still room for improvement. That is, the brominated flame retardant containing a brominated bisphenol S derivative has a problem of thermal decomposition during molding of a resin composition containing the same. When thermal decomposition occurs, decomposition products such as highly toxic acrolein and halogen-based compounds are generated and may be released into the working environment. For this reason, there is a need to develop a flame-retardant resin composition that also has the property of being less likely to generate decomposition products even under heating during molding, etc. (hereinafter referred to as "heat resistance").

[0010] Therefore, a main object of the present invention is to provide a flame-retardant resin composition which has good flame retardancy, is less likely to cause blooming, and has excellent heat resistance. [Means for solving the problem]

[0011] As a result of intensive research into achieving the above object, the inventors have discovered that the above object can be achieved by employing a combination of specific compounds as a flame retardant, and have thus completed the present invention.

[0012] That is, the present invention relates to the following polypropylene resin composition. 1. The following components (A) to (D): (A) Polypropylene resin: 100 parts by weight (B) The following general formula (1) [ka] [In the formula, R 1 and R 2 are the same or different and each represents hydrogen or an alkyl group having 1 to 3 carbon atoms which may have a substituent. m and n are the same or different and each represents an integer of 0 to 2. a mixture of said derivative b1, in which m+n is 4, and said derivative b2, in which m+n is 0 to 3, in which the ratio of b1 to b2 [b1:b2] is 92%:8% to 70%:30% as determined by an area percentage method using liquid chromatography: 2 to 50 parts by weight; (C) (c1) at least one of tetrabromobisphenol A bis(2,3-dibromopropyl) ether and (c2) tris(2,3-dibromopropyl) isocyanurate: 0.2 to 20 parts by weight, (D) At least one of antimony trioxide, antimony pentoxide, zinc molybdate, boron trioxide, and zinc borate: 1 to 20 parts by weight A flame-retardant polypropylene-based resin composition comprising: 2. R 1 and R 2 and are the same or different and are bromine-substituted propyl groups. 3. R 1 and R 2and are the same or different and are a 2,3-dibromopropyl group or a 2-hydroxy-3-bromopropyl group. 4. The flame-retardant polypropylene resin composition according to any one of items 1 to 3, wherein the (B) component and the (C) component are contained in a ratio of 40% by weight:60% by weight to 90% by weight:10% by weight of the (B) component:the (C) component. 5. A molded article obtained by molding the flame-retardant polypropylene resin composition according to any one of items 1 to 4. Effect of the Invention

[0013] According to the present invention, it is possible to provide a flame-retardant resin composition that has good flame retardancy, is less likely to cause blooming, and has excellent heat resistance. In particular, the composition of the present invention uses a first flame-retardant component and a second flame-retardant component described below in specific amounts, and therefore can effectively suppress blooming while obtaining high heat resistance. In other words, it is possible to solve the problems of the flame retardant seeping out onto the surface of a molded article and the flame retardant volatilizing during molding at once.

[0014] The flame-retardant polypropylene resin composition of the present invention having such characteristics can be suitably used for the production (molding) of polypropylene products that require flame retardancy, such as electronic parts, home appliances, medical devices, and building materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1. Flame-retardant polypropylene resin composition (1) Constitution of resin composition The flame-retardant polypropylene resin composition of the present invention (the composition of the present invention) comprises the following components (A) to (D): (A) Polypropylene resin: 100 parts by weight (B) The following general formula (1) [ka] [In the formula, R1 and R 2 are the same or different and represent hydrogen or an alkyl group having 1 to 3 carbon atoms which may have a substituent; m and n are the same or different and represent an integer of 0 to 2; and a mixture of the derivative b1 in which m+n is 4 and the derivative b2 in which m+n is 0 to 3, wherein the ratio of b1 to b2 [b1:b2] measured by an area percentage method using liquid chromatography is 92%:8%-70%:30%, (C) (c1) at least one of tetrabromobisphenol A bis(2,3-dibromopropyl) ether and (c2) tris(2,3-dibromopropyl) isocyanurate: 0.2 to 20 parts by weight, (D) At least one of antimony trioxide, antimony pentoxide, zinc molybdate, boron trioxide, and zinc borate: 1 to 20 parts by weight Each of the components constituting the composition of the present invention will be described below.

[0016] (A) Polypropylene resin The polypropylene-based resin may be any one containing [-CH(CH3)CH2-] as a monomer, and may be either a homopolymer or a copolymer. It may also be a polymer alloy containing a polypropylene resin. These polypropylene-based resins may be publicly known or commercially available.

[0017] When the polypropylene-based resin is a homopolymer, it may be either isotactic or syndiotactic.

[0018] When the polypropylene resin is a copolymer, the other monomer is not particularly limited as long as it does not impede the effects of the present invention, and examples thereof include at least one of ethylene, butene, hexene, octene, etc. The content of the other monomer varies depending on the type of monomer used, but is usually preferably 40 mol % or less (particularly 30 mol % or less).

[0019] The polypropylene-based resin may be a polymer alloy containing a polypropylene resin. For example, at least one of polyamide, polylactic acid, polyester, polyacrylate, ethylene propylene rubber, polystyrene, etc. may be used. The polypropylene content in the polymer alloy may be set to, for example, 60 to 90% by weight, but is not limited thereto.

[0020] The weight average molecular weight of the polypropylene resin may be within a range of, for example, about 100,000 to 1,500,000, but is not limited thereto.

[0021] The MFR (JIS K7210, measurement temperature 230° C.) of the polypropylene resin may be within a range of, for example, about 0.5 to 50, but is not limited thereto.

[0022] The content of the polypropylene resin in the composition of the present invention is not particularly limited, but can be appropriately set within the range of 80 to 100% by weight. Therefore, for example, it can be set within the range of 90 to 95% by weight. That is, resin components other than the polypropylene resin (e.g., polyamide, polylactic acid, polyester, polyacrylate, ethylene propylene rubber, polystyrene, etc.) may be contained within a range that does not impair the effects of the present invention. In this case, the content of the resin components may be set so that the content of the polypropylene resin is within the above range.

[0023] (B) First flame retardant component In the composition of the present invention, as one of the flame retardant components, a compound represented by the following general formula (1) [ka] [In the formula, R 1 and R 2 are the same or different and each represents hydrogen or an alkyl group having 1 to 3 carbon atoms which may have a substituent. m and n are the same or different and each represents an integer of 0 to 2. The present invention uses a bisphenol S derivative represented by the formula: wherein b1 is a bisphenol S derivative having m+n of 4, and b2 is a bisphenol S derivative having m+n of 0 to 3, and wherein the ratio of b1 to b2 [b1:b2] is 92%:8% to 70%:30% as determined by an area percentage method using liquid chromatography (hereinafter also referred to as a "first flame retardant component").

[0024] The first flame retardant component is a mixture of the above bisphenol S derivatives, particularly a derivative in which m+n is 4 (i.e., a derivative in which the total number of bromine atoms substituted on the phenyl group is 4; hereinafter referred to as "tetra-form") and a derivative in which m+n is 0-3 (i.e., a derivative in which the total number of bromine atoms substituted on the phenyl group is 0-3; hereinafter referred to as "non-tetra-form"). The mixture has a mixing ratio of the above tetra-form and non-tetra-form, which is 92%:8%-70%:30%. Within this mixing ratio range, better blooming suppression effect and heat resistance can be obtained.

[0025] The above mixing ratio is a value determined by the area percentage method using liquid chromatography, i.e., the total area of ​​the peaks detected in the chromatogram is taken as 100%, and the ratio of the total peak area of ​​the tetra-forms to the total peak area of ​​the non-tetra-forms is calculated and quantified.

[0026] The liquid chromatography apparatus and operating conditions used in the present invention are shown below. a) Equipment used: ACQUITY UPLC H-Class, Column: ACQUITY UPLC BEH C 18 1.7μm, inner diameter 2.1mm x length 100mm (Waters) b)Flow rate: 0.35mL / min c) Column temperature: 40°C d) Analysis time: 9 minutes e) Mobile phase: A linear gradient of a mixture of acetonitrile / 0.1% formic acid (volume ratio 50%:50%) → a mixture of acetonitrile / 0.1% formic acid (volume ratio 95%:5%) (5.5 min) → an acetonitrile / 0.1% formic acid (volume ratio 95%:5%) (9 min) f) Measurement wavelength: UV210~410nm (analysis UV254nm).

[0027] In the above general formula (1), R 1 and R 2 are the same or different and represent hydrogen or an alkyl group having 1 to 3 carbon atoms which may have a substituent.

[0028] Examples of the above-mentioned substituent include a halogen group and a hydroxyl group. The alkyl group having 1 to 3 carbon atoms, which may have a substituent, is not limited, but is preferably a bromine-substituted propyl group. The bromine-substituted propyl group is not limited to those in which all the substituents are bromine, as long as at least one of the substituents is bromine. As such a bromine-substituted propyl group, a 2,3-dibromopropyl group or a 2-hydroxy-3-bromopropyl group is particularly preferred.

[0029] In the above general formula (1), m and n are the same or different and each represents an integer of 0 to 2. When m+n is 4 (tetramer), two bromine atoms (total of 4) are substituted on each phenyl group. Specific examples of suitable tetramers are shown below. [ka]

[0030] When m+n is 0 to 3 (non-tetra form), the total number of bromine atoms substituted on the phenyl group is 3 or less. Non-tetra forms are specifically classified into "tri forms" where m+n is 3, "di forms" where m+n is 2, "mono forms" where m+n is 1, and "zero forms" where m+n is 0. Specific examples of tri forms, di forms, mono forms, and zero forms are shown below in order.

[0031] Examples of tri-forms include the following: [ka]

[0032] Examples of the diform include the following: [ka]

[0033] Examples of monoliths include the following: [ka]

[0034] Examples of zero bodies include the following: [ka]

[0035] As described above, the first flame retardant component is substantially a mixture of 70-92% tetramers and 8-30% non-tetramers. The content ratio is not limited as long as it is within this range, but it is more preferable that the content ratio is 92%:8%-75%:25%. If the content ratio of tetramers exceeds 92%, the occurrence of blooming after kneading with the polyolefin resin may not be sufficiently suppressed. If the content ratio of tetramers is less than 70%, the heat resistance may deteriorate.

[0036] The first flame retardant component itself can be a known or commercially available product. It can also be produced according to a known production method. For example, it can be suitably produced according to the method described in Japanese Patent No. 4817726.

[0037] The content of the first flame retardant component is usually 2 to 50 parts by weight, preferably 3 to 20 parts by weight, and more preferably 4 to 15 parts by weight, relative to 100 parts by weight of the polypropylene resin. By setting the content within the above range, excellent effects can be obtained in terms of flame retardancy, blooming suppression effect, and heat resistance.

[0038] (C) Secondary flame retardant component In the composition of the present invention, at least one of (c1) tetrabromobisphenol A bis(2,3-dibromopropyl)ether and (c2) tris(2,3-dibromopropyl)isocyanurate (hereinafter also referred to as "second flame retardant component") is used. By allowing the first flame retardant component and the second flame retardant component to coexist in the composition of the present invention, it is possible to obtain a high bleeding suppression effect as well as excellent heat resistance.

[0039] From the viewpoint of the above-mentioned effects, the content of the second flame retardant component is usually 0.2 to 20 parts by weight, and preferably 0.5 to 15 parts by weight, per 100 parts by weight of the polypropylene resin.

[0040] The weight ratio of the first flame retardant component to the second flame retardant component is not limited, but is preferably 40% by weight:60% by weight to 90% by weight:10% by weight when the total of the two is 100% by weight. By using the two in combination at such a weight ratio, the composition of the present invention can be provided with better bleed suppression effect and heat resistance.

[0041] (D) Flame retardant synergist The composition of the present invention contains at least one selected from the group consisting of antimony trioxide, antimony pentoxide, zinc molybdate, boron trioxide, and zinc borate (hereinafter also referred to as "flame retardant assistant"). When these flame retardant assistants are contained, better flame retardant performance can be exhibited. Among the above, at least one of antimony trioxide and antimony pentoxide is preferred, and antimony trioxide is more preferred in that it can impart a particularly high level of flame retardancy. The properties of the flame retardant assistant are not particularly limited, and for example, a powder-like form can be used. These flame retardant assistants can be publicly known or commercially available.

[0042] The content of the flame retardant auxiliary in the composition of the present invention is usually 1 to 20 parts by weight, and preferably 2 to 15 parts by weight, which can provide high flame retardancy, high bleeding suppression effect, and excellent heat resistance.

[0043] (E) Other additives In the composition of the present invention, various additives that are blended in known or commercially available resin compositions or molded articles thereof can be added as necessary within the range that does not impair the effects of the present invention. For example, in addition to resin components other than polypropylene-based resins, dispersants, surfactants, weather stabilizers, antioxidants, UV absorbers, antifogging agents, antistatic agents, antibacterial agents, impact resistance agents, foaming agents, fillers, conductive powders, nucleating agents, crosslinking agents, colorants, lubricants, etc. can be mentioned.

[0044] (2) Properties of the composition of the present invention The properties of the composition of the present invention are not particularly limited, and it may be a solid (powder) at room temperature and pressure, or may be in a molten state under heating. It may also be in the form of a solid obtained by solidifying a melt. Furthermore, it may be a liquid obtained by dissolving or dispersing the above solid in a solvent as necessary.

[0045] (3) Preparation of the composition of the present invention The method for preparing the composition of the present invention is not particularly limited as long as each component can be mixed uniformly. In addition, the components may be mixed to obtain an unmolded / unmelted mixture (powdered), or may be melted and solidified to obtain a solid. For example, the components constituting the composition of the present invention may be mixed in advance in a mixer such as a Henschel mixer, a tumbler mixer, or a rotor mixer, and then fed into a kneader heated to the melting temperature of the polypropylene resin to obtain resin composition pellets.

[0046] Alternatively, each component may be fed to the kneader separately by a quantitative feeder without being mixed in advance (premixed). Each component (e.g., the first flame-retardant component, the second flame-retardant component, the flame-retardant assistant, etc.) and the polypropylene-based resin may be fed to the kneader separately by a quantitative feeder.

[0047] 2. Molded body The present invention also includes a molded article obtained by molding the composition of the present invention. In this case, the size, shape, etc. of the molded article can be appropriately set depending on the application, usage form, etc. of the molded article.

[0048] The molding method for the molded article is not limited as long as it is a method capable of molding a melt of the composition of the present invention, a sheet of the composition of the present invention, etc., and various molding methods can be adopted, such as press molding, injection molding, extrusion molding, blow molding, vacuum molding, etc. Therefore, for example, known or commercially available molding machines such as a heat compression molding machine and an injection molding machine can also be used.

[0049] The uses of the molded article of the present invention are not particularly limited as long as the article is at least flame retardant, and examples thereof include parts and covers for washing machines, refrigerators, dish dryers, rice cookers, electric fans, televisions, personal computers, stereos, microwave ovens, heated toilets, irons, etc.; electronic device circuit boards for mobile phones, personal computers, printers, facsimiles, etc.; parts and covers for air conditioners, stoves, cooking stoves, fan heaters, water heaters, etc.; building materials, parts and interior materials for automobiles, ships, aircraft, etc. EXAMPLES

[0050] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0051] 1. Starting materials (A) Polypropylene resin As the polypropylene-based resin, a commercially available polypropylene resin (product name "Prime Polypro J707G" (MFR: 30 g / 10 min, block-PP), manufactured by Prime Polymer (PP)) was used.

[0052] (B) First flame retardant component The first flame retardant component was prepared by the following method. Production Example 1 (Product of the Invention) A glass reaction vessel equipped with a stirrer, a condenser, a thermometer, a dropping funnel and a heating / cooling device was prepared. 1000 g of water and 250 g (1 mole) of bisphenol S were placed in the reaction vessel. 591 g (3.7 moles) of bromine was added dropwise over 2 hours while stirring the contents, thereby replacing the phenyl group with bromine. The temperature of the contents rose from 5°C to 40°C by the dropping. After the dropping was completed, the reaction was continued for another hour. Here, since the reaction solution was reddish due to free bromine, sodium sulfite (reducing agent) was added until the redness disappeared. The reduction reaction was completed over another hour. The amount of bromine was set to 591 g in Production Example 1 in order to set the weight ratio of tetramer to non-tetramer after the substitution reaction to about 9:1. Next, 464 g of 50% aqueous sodium hydroxide solution (5.8 moles of sodium hydroxide) was added to the reaction solution over 30 minutes. The pH of the reaction solution after the addition was 9 or higher. The temperature of the reaction solution rose from 5°C to 40°C due to the addition. This addition was carried out for the purpose of neutralizing hydrogen bromide produced by the substitution reaction and converting bromine-substituted bisphenol S into a water-soluble alkali metal salt (Na salt). Next, the reaction solution was refluxed while adding 400 g of isopropyl alcohol (IPA) (boiling point 82.5°C) and 187.4 g (2.45 moles) of allyl chloride. The temperature of the solution rose from 40 to 83°C due to the reflux. This operation converts bromine-substituted bisphenol S into an allyl ether. When the pH of the reaction solution became acidic during the reaction, aqueous sodium hydroxide solution was added until it became alkaline. The end point of the reaction was determined as follows. That is, a small amount of the reaction solution was taken out, and an aqueous hydrochloric acid solution was added. The end point was the time when the reaction solution no longer showed a cloudy or milky color. In Production Example 1, it took 8 hours for the reaction solution to no longer show a cloudy or milky color. After the reaction was completed, needle-shaped crystals of diallyl ether were formed in the reaction vessel. Next, after removing the liquid components from the reaction vessel, water was added to the reaction vessel to wash the vessel and the reaction product, and unnecessary alkali salts, IPA, allyl chloride, etc. were dissolved and removed. The reaction product was then transferred to a porcelain filter, and 1000 ml of water was poured into it to completely dissolve and remove unnecessary alkali salts, IPA, allyl chloride, etc. The washed reaction product was transferred to a 2-liter glass eggplant flask, which was then connected to an evaporator at water temperature (60°C) and dried under reduced pressure at a reduced pressure of 20 Torr. Next, a glass reaction vessel equipped with a stirrer, condenser, thermometer, dropping funnel, and heating / cooling device was prepared. The dried reaction product was placed in the reaction vessel, and 600 g of methylene chloride (solvent) was added to completely dissolve it. 2 moles of bromine were dripped into this solution little by little using a dropping funnel. This dripping adds bromine to the unsaturated bond of the allyl group of the bromine-substituted bisphenol S derivative. Since this reaction is accompanied by rapid heat generation, stirring and cooling were performed sufficiently. The liquid temperature during the reaction was controlled so as not to exceed 40° C. The end point of the bromine addition reaction was determined to be when the reaction liquid retained a reddish color after the completion of the dropwise addition of a predetermined amount of bromine. In Production Example 1, it took 2 hours from the start of the dropwise addition of bromine. After that, the reaction was continued for another hour for maturation. Next, 1000 ml of water was added to the reaction solution and stirred vigorously to dissolve unnecessary unreacted bromine in the aqueous phase, and then the aqueous phase was removed by repeated decantation. Next, the reaction product was poured into 2000 ml of methanol in a vigorously stirred state over 5 minutes to be reprecipitated. The precipitate was once crushed and further left to stand in methanol for 10 hours to crystallize. Next, most of the methanol was removed by filtration, and the mixture was transferred to a 2000 ml glass eggplant flask. The eggplant flask was connected to a hot water (70°C) evaporator, and unnecessary solvents (methanol, water, etc.) were distilled off at a reduced pressure of 10 Torr. The yield of the reaction product (bromine-based flame retardant) was 745 g. The area percentage of tetramer:non-tetramer in the reaction product was identified by liquid chromatography and found to be 89:11. The melting endothermic peak temperature of the reaction product was measured by differential scanning calorimetry and a melting point peak was confirmed at 122°C. The chemical formula of the reaction product obtained is shown below. [ka]

[0053] Production Example 2 (Product of the Invention) A bromine-based flame retardant was obtained in the same manner as in Production Example 1, except that 559.3 g (3.5 mol) of bromine was added to bisphenol S and the amount of 50% aqueous sodium hydroxide solution added for the allyl etherification reaction was 448 g (5.6 mol as sodium hydroxide). The yield of the reaction product (bromine-based flame retardant) was 711 g. The area percentage of tetramer:non-tetramer in the reaction product was identified by liquid chromatography and found to be 73:27. The melting endothermic peak temperature of the reaction product was measured by differential scanning calorimetry and a melting point peak was confirmed at 105°C. The chemical formula of the reaction product obtained is shown below. [ka]

[0054] Manufacturing example 3 (comparative product) A brominated flame retardant was obtained in the same manner as in Production Example 1, except that tetrabromobisphenol S (TBS, product name EB400S, manufactured by Manac Co., Ltd.), which contains 95% by weight or more of bisphenol S with a bromine substitution number of 4 (tetra form), was used as the starting material for allyl etherification, and 412 g (4 moles) of sodium bromide was dissolved in the reaction solution as a reaction catalyst for allyl etherification. The yield of the reaction product (brominated flame retardant) was 765 g. The area percentage of the tetramer:non-tetramer in the reaction product was identified by liquid chromatography and found to be 99:1. The melting endothermic peak temperature of the reaction product was measured by differential scanning calorimetry and a melting point peak was confirmed at 120°C. The chemical formula of the reaction product obtained is shown below. [ka]

[0055] Manufacturing example 4 (comparative product) A bromine-based flame retardant was obtained in the same manner as in Production Example 1, except that 527.3 g (3.3 mol) of bromine was added to bisphenol S and the amount of 50% aqueous sodium hydroxide solution added for the allyl etherification reaction was 432 g (5.4 mol as sodium hydroxide). The yield of the reaction product (bromine-based flame retardant) was 670 g. The area percentage of tetramer:non-tetramer in the reaction product was identified by liquid chromatography and found to be 65:35. In addition, the melting endothermic peak temperature of the reaction product was measured by differential scanning calorimetry and a melting point peak was confirmed at 98°C. The chemical formula of the obtained reaction product is shown below. [ka]

[0056] (C) Secondary flame retardant component As the second flame retardant component, the following commercially available product was used. Product name: "Pyroguard SR720" (Tetrabromobisphenol A bis(2,3-dibromopropyl ether), manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (hereinafter referred to as "TBA-DBP") Product name: "TAIC-6B" (Tris(2,3-dibromopropyl)isocyanurate), manufactured by Nippon Kasei Chemical Industry Co., Ltd. (hereinafter referred to as "TBIC")

[0057] (D) Flame retardant synergist Powdered antimony trioxide (average particle size: 3 μm) was used as the flame retardant assistant.

[0058] 2. Resin composition Examples 1 to 6 and Comparative Examples 1 to 10 The components (A) to (D) shown in 1 above were dry-blended in the mixing ratios shown in Tables 1 and 2, and the mixture was extrusion-kneaded at a temperature of 200 to 210°C using a twin-screw kneader "KTX30 type" (manufactured by Kobe Steel, Ltd.), and the strands were cut to obtain pellet-shaped flame-retardant resin compositions. The obtained pellets were molded using an injection molding machine (manufactured by Nissei Plastic Industrial Co., Ltd., FE80S 18ASE, cylinder temperature 200°C, mold temperature 40°C) to produce a vertical combustion test piece (127 mm × 12.7 mm, thickness; 1 / 32 inch) defined in UL94. Similarly, using an injection molding machine (manufactured by Nissei Plastic Industrial Co., Ltd., FE80S 18ASE, cylinder temperature 200°C, mold temperature 40°C), a plate for blooming property evaluation (35 mm × 48 mm × thickness 1.5 mm) was produced.

[0059] Test Example 1 Using the samples prepared in each example and comparative example, the following physical properties were examined respectively. The results are also shown in Table 1.

[0060] (1) Flammability The flammability of the resin composition was evaluated by performing a vertical combustion test using the above vertical combustion test piece in accordance with the safety standard "UL-94 Combustion Test" of Underwriter Laboratories, USA. The UL94 combustion test is roughly classified into two types: a horizontal test (HB method) and a vertical test (V method). The comprehensive flammability evaluation is that FAIL < HB < V-2 < V-1 < V-0, with the flame retardancy increasing in this order. V-0 indicates the highest flame retardancy.

[0061] (2) Blooming property The above plate for blooming property test was heated at 80°C for 48 hours, and the difference in glossiness (gloss difference) before and after the test was measured at a measurement angle of 60° using a gloss checker IG-320 manufactured by Horiba, Ltd. Due to the blooming of the flame retardant, the surface of the molded product becomes white and the gloss decreases. Generally, since the gloss difference at which whitening is visually observed is 20 or more, when the gloss difference is less than 20, it is regarded as "no blooming", and when the gloss difference is 20 or more, it is regarded as "blooming".

[0062] (3) Heat resistance When brominated flame retardants decompose during molding, highly toxic decomposition products such as acrolein and halogenated compounds are generated and released into the work environment. To simulate the heating conditions during molding, 0.1g of brominated flame retardants (the total amount of the first and second flame retardants if a second flame retardant is included) was heated at 230°C for 15 minutes in a sealed container, and the concentration of total volatile organic compounds (TVOC) was measured using an Agilent Technologies headspace sampler gas chromatograph mass spectrometer. When the TVOC ratio to the brominated flame retardant was 1ppm or more, it was considered to have "poor heat resistance," and when it was less than 1ppm, it was considered to have "good heat resistance."

[0063] [Table 1]

[0064] [Table 2]

[0065] As is clear from the results in Tables 1 and 2, the molded article of the present invention exhibits excellent flame retardancy, does not bloom, and maintains an excellent appearance. At the same time, since the TVOC value is less than 1 ppm (especially 0.70 ppm or less), it is understood that gases (harmful gases with odors) that may be generated during molding can be effectively suppressed (i.e., the heat resistance is excellent).

[0066] In contrast, it is clear that the molded articles of the comparative examples have problems with at least either blooming or heat resistance.

[0067] More specifically, as shown in Table 2, in Comparative Example 1, the mixing ratio of tetra- and non-tetra-compounds is within the range of the present invention, but since it does not contain a second flame retardant component, it has a higher TVOC value than Example 4, in which the first and second flame retardant components are used in combination. Similarly, in Comparative Example 2, the mixing ratio of tetra- and non-tetra-compounds is within the range of the present invention, but since it does not contain a second flame retardant component, it has a higher TVOC value than Example 5 or Example 6, in which the first and second flame retardant components are used in combination.

[0068] In Comparative Example 3, by blending 10 parts by weight of a first flame retardant component having a tetra- to non-tetra-compound mixing ratio of 99:1, gas generation was suppressed and a high level of flame retardancy of V-0 level could be imparted. However, blooming occurred and the appearance of the molded article was significantly deteriorated, indicating that the tetra-compound has no effect in suppressing blooming.

[0069] In Comparative Example 4, a high degree of flame retardancy is imparted by blending 10 parts by weight of a first flame retardant component having a high non-tetra content with a mixing ratio of tetra- and non-tetra-components of 65:35, and excellent appearance is maintained. However, since it contains a large amount of non-tetra-components, it has poor heat resistance and may generate gas during processing.

[0070] In Comparative Examples 5 and 6, the second flame retardant components TBA-DBP and TBIC are blended in an amount of 10 parts by weight each, thereby imparting a high level of flame retardancy and suppressing gas generation. However, since the first flame retardant component is not contained at all, blooming occurs and the appearance of the molded article is significantly deteriorated.

[0071] In Comparative Example 7, 10 parts by weight of a mixture of the first flame retardant component containing 1% non-tetra-compounds and the second flame retardant component TBA-DBP in a ratio of 9:1 was blended, which suppressed gas generation and imparted a high level of flame retardancy. However, since the content of non-tetra-compounds was low, blooming occurred, significantly deteriorating the appearance of the molded article.

[0072] In Comparative Example 8, a high level of flame retardancy was imparted by blending 10 parts by weight of a first flame retardant component containing 35% non-tetra-form and a second flame retardant component, TBA-DBP, in a 9:1 ratio, and the composition retained an excellent appearance, but it was found to have poor heat resistance and may generate gas during processing.

[0073] In Comparative Example 9, the first flame-retardant component and the second flame-retardant component are used in combination, but since the mixing ratio of tetra- to non-tetra- in the first flame-retardant component is 99:1, blooming occurs and the appearance of the molded product is significantly deteriorated.

[0074] Comparative Example 10 uses a first flame retardant component with a high non-tetra content, that is, a mixture ratio of tetra- and non-tetra-components of 65:35, and therefore has poor heat resistance and may generate gas during processing.

Claims

1. The following components (A) to (D): (A) Polypropylene resin: 100 parts by weight (B) a compound represented by the following general formula (1): 【Chemistry 13】 [In the formula, R １ and R ２ are the same or different and represent hydrogen or an alkyl group having 1 to 3 carbon atoms which may have a substituent. m and n are the same or different and each represents an integer of 0 to 2. a mixture of said derivative b1, in which m+n is 4, and said derivative b2, in which m+n is 0 to 3, in which the ratio of b1 to b2 [b1:b2] is 92%:8% to 70%:30% as determined by an area percentage method using liquid chromatography: 2 to 50 parts by weight; (C) (c1) at least one of tetrabromobisphenol A bis(2,3-dibromopropyl)ether and (c2) tris(2,3-dibromopropyl)isocyanurate: 0.2 to 20 parts by weight, (D) At least one of antimony trioxide, antimony pentoxide, zinc molybdate, boron trioxide, and zinc borate: 1 to 20 parts by weight and When the total amount of the (B) component and the (C) component is taken as 100% by weight, the (B) component:the (C) component is contained in a ratio of 40% by weight:60% by weight to 90% by weight:10% by weight. A flame-retardant polypropylene resin composition comprising:

2. R １ and R ２ and are the same or different and are bromine-substituted propyl groups.

3. R １ and R ２ and are the same or different and are a 2,3-dibromopropyl group or a 2-hydroxy-3-bromopropyl group.

4. A molded body obtained by molding the flame-retardant polypropylene-based resin composition described in any one of claims 1 to 3.

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