Flame-retardant polypropylene resin composition

Abstract

The present invention provides a flame-retardant resin composition which is excellent in flame retardancy and heat resistance and is less likely to cause blooming. The present invention relates to a flame-retardant polypropylene resin composition characterized by comprising: (A) a polypropylene resin: 100 parts by weight; (B) a mixture of specific bisphenol S derivatives: 2 to 50 parts by weight; (C) at least one of (c1) tetrabromobisphenol A bis(2,3-dibromopropyl) ether and (c2) tris(2,3-dibromopropyl) isocyanurate: 0.2 to 20 parts by weight; and (D) at least one of antimony trioxide, antimony pentoxide, zinc molybdate, boron trioxide and zinc borate: 1 to 20 parts by weight.

Description

Technical Field

[0001] This invention relates to a novel flame-retardant polypropylene resin composition. Background Technology

[0002] Polyolefins, such as polypropylene, are widely used in various fields, including building materials, electrical machinery materials, vehicle parts, automotive interior materials, wire sheathing, and various industrial and household products, due to their light weight, high strength, good water resistance, chemical resistance, and electrical insulation properties, as well as ease of molding and processing. However, polyolefins are flammable. Therefore, many methods have been proposed for flame retardant treatment of polyolefins.

[0003] As a method for flame retardancy, one current approach involves incorporating flame retardants into resins. For example, flame retardants containing bromine compounds and antimony compounds exist; among the bromine compounds, brominated bisphenol S derivatives are known to have high flame retardancy. Therefore, various resin compositions incorporating these flame retardants have been proposed.

[0004] For example, a flame-retardant polyolefin resin composition having a ratio of (A) 70-98% by weight of a polyolefin resin and (B) 2-30% by weight of a brominated flame retardant is disclosed, wherein the composition contains a specific compound as the brominated flame retardant (Patent Document 1). Meanwhile, Patent Document 1 also describes the use of antimony trioxide as a flame-retardant additive in combination with the brominated flame retardant (Patent Document 1).

[0005] For example, there is a known polypropylene resin composition comprising a polypropylene resin (A) that meets specific conditions, a filler (B), a halogenated flame retardant (C) that meets specific conditions, and a flame retardant additive (E) (Patent Document 2).

[0006] These flame-retardant resin compositions can achieve a certain degree of flame retardancy, but when polyolefin resins are mixed with flame retardants or after such mixing (including after molding), flame retardants or other substances are prone to seep out and turn white on the resin surface (blooming).

[0007] Therefore, in order to develop a flame retardant that can suppress blooming, the inventors have previously proposed a brominated flame retardant containing a brominated bisphenol S derivative (Patent Document 3).

[0008] Existing technical documents

[0009] Patent documents

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2004-99780

[0011] [Patent Document 2] Japanese Patent Application Publication No. 2015-78276

[0012] [Patent Document 3] Japanese Patent No. 4817726 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] However, while brominated flame retardants, as shown in Patent Document 3, exhibit excellent bloom suppression effects, there is still room for further improvement. Specifically, brominated flame retardants containing brominated bisphenol S derivatives can lead to thermal decomposition of the resin composition containing such retardants during molding and processing. In the event of thermal decomposition, there is a risk of releasing highly toxic acrolein and halogenated compounds into the operating environment. Therefore, it is necessary to develop flame-retardant resin compositions that simultaneously possess the property of minimizing the generation of decomposition products even under heating during molding and processing (hereinafter referred to as "heat resistance").

[0015] Therefore, the main objective of this invention is to provide a flame-retardant resin composition that has good flame retardancy, is not prone to blooming, and has excellent heat resistance.

[0016] Methods for solving problems

[0017] As a result of repeated and in-depth research conducted by the inventors to achieve the above-mentioned objectives, they discovered that the above-mentioned objectives could be achieved by using a combination of specific compounds as flame retardants, and thus completed the present invention.

[0018] That is, the present invention relates to the following polypropylene resin compositions.

[0019] 1. A flame-retardant polypropylene resin composition, characterized in that it comprises the following components (A) to (D):

[0020] (A) Polypropylene resin: 100 parts by weight;

[0021] (B) The bisphenol S derivative represented by the following general formula (1) is a mixture of the derivative b1 with m+n of 4 and the derivative b2 with m+n of 0 to 3, and is a mixture of b1 and b2 in a ratio [b1:b2] of 92%:8% to 70%:30% obtained by the area percentage method using liquid chromatography: 2 to 50 parts by weight

[0022] [Chemistry 1]

[0023]

[0024] [In the formula, R] 1 and R 2 [The same or different denote hydrogen or alkyl groups having 1 to 3 carbon atoms that may have substituents; m and n are the same or different denote integers from 0 to 2];

[0025] At least one of (C)(c1) tetrabromobisphenol A bis(2,3-dibromopropyl) ether and (c2) tris(2,3-dibromopropyl) isocyanurate: 0.2 to 20 parts by weight; and

[0026] (D) At least one of antimony trioxide, antimony pentoxide, zinc molybdate, boron trioxide and zinc borate: 1 to 20 parts by weight.

[0027] 2. The flame-retardant polypropylene resin composition according to claim 1, wherein R 1 and R 2 The same or different is bromine-substituted propyl.

[0028] 3. The flame-retardant polypropylene resin composition according to claim 1 or 2, wherein R 1 and R 2 It may be the same as or different from 2,3-dibromopropyl or 2-hydroxy-3-bromopropyl.

[0029] 4. The flame-retardant polypropylene resin composition according to any one of items 1 to 3, wherein the (B) component and the (C) component, when the total amount of the two is set to 100% by weight, are included in the composition in a ratio of (B) component: (C) component = 40% by weight: 60% to 90% by weight: 10% by weight.

[0030] 5. A molded article formed from the flame-retardant polypropylene resin composition described in any one of items 1 to 4.

[0031] Invention Effects

[0032] According to the present invention, a flame-retardant resin composition that exhibits good flame retardancy, is not prone to blooming, and has excellent heat resistance can be provided. In particular, the first flame-retardant component and the second flame-retardant component, as described later, are used together in specific amounts in the composition of the present invention, so that high heat resistance can be obtained while effectively suppressing blooming. That is, the problems of flame retardant seeping onto the surface of the molded article and flame retardant volatilization during molding processing can be eliminated in one fell swoop.

[0033] The flame-retardant polypropylene resin composition of the present invention, having these characteristics, is suitable for the manufacture (molding) of polypropylene articles requiring flame retardancy. For example, it can be widely used as electronic components, household appliances, medical devices, building materials, etc. Detailed Implementation

[0034] 1. Flame-retardant polypropylene resin composition

[0035] (1) Composition of the resin composition

[0036] The flame-retardant polypropylene resin composition of the present invention (the composition of the present invention) is characterized in that it comprises the components (A) to (D) shown below:

[0037] (A) Polypropylene resin: 100 parts by weight

[0038] (B) The bisphenol S derivative represented by the following general formula (1) is a mixture of the derivative b1 with m+n of 4 and the derivative b2 with m+n of 0 to 3, and is a mixture of b1 and b2 in a ratio [b1:b2] of 92%:8% to 70%:30% obtained by the area percentage method using liquid chromatography: 2 to 50 parts by weight

[0039] [Chemistry 2]

[0040]

[0041] [In the formula, R] 1 and R 2 [The same or different denote hydrogen or alkyl groups having 1 to 3 carbon atoms that may have substituents; m and n are the same or different denote integers from 0 to 2];

[0042] At least one of (C)(c1) tetrabromobisphenol A bis(2,3-dibromopropyl) ether and (c2) tris(2,3-dibromopropyl) isocyanurate: 0.2 to 20 parts by weight; and

[0043] (D) At least one of antimony trioxide, antimony pentoxide, zinc molybdate, boron trioxide and zinc borate: 1 to 20 parts by weight.

[0044] The components constituting the composition of the present invention will be described below.

[0045] (A) Polypropylene resin

[0046] Polypropylene resins can be any monomer containing [-CH(CH3)CH2-], and can be either homopolymers or copolymers. They can also be polymer alloys containing polypropylene resins. These polypropylene resins can use known or commercially available substances.

[0047] When the polypropylene resin is a homopolymer, it can be either isotactic or syndiotactic.

[0048] When the polypropylene resin is a copolymer, there are no particular limitations on other monomers, as long as they do not impair the effects of the present invention. Examples include at least one olefin with 2 to 10 carbon atoms, such as ethylene, butene, hexene, and octene. The content of other monomers will depend on the type of monomer used, but is generally preferred to be 40 mol% or less (especially 30 mol% or less).

[0049] Meanwhile, the polypropylene resin can be a polymer alloy containing polypropylene resin. Examples include at least one of polyamide, polylactic acid, polyester, polyacrylate, ethylene propylene rubber, and polystyrene. When it is a polymer alloy, the polypropylene content can be set to, for example, 60 to 90% by weight, but is not limited thereto.

[0050] The weight-average molecular weight of polypropylene resins can be in the range of approximately 100,000 to 1,500,000, but is not limited to this range.

[0051] The MFR (Japanese Industrial Standard JIS K7210, measuring temperature 230°C) of polypropylene resins can be in the range of approximately 0.5 to 50, but is not limited to this range.

[0052] The content of polypropylene resin in the composition of the present invention is not particularly limited, and can generally be suitably set in the range of 80 to 100% by weight. Accordingly, it can be set in the range of, for example, 90 to 95% by weight. That is, without impairing the effects of the present invention, resin components other than polypropylene resin (e.g., polyamide, polylactic acid, polyester, polyacrylate, ethylene propylene rubber, polystyrene, etc.) may be included. In this case, the content of the resin component can be set in such a way that the content of polypropylene resin is within the above-mentioned range.

[0053] (B) First flame retardant component

[0054] As one of the flame retardant components, the composition of the present invention uses a bisphenol S derivative represented by the following general formula (1), which is a mixture of the derivative b1 with m+n of 4 and the derivative b2 with m+n of 0 to 3, and is a mixture of b1 and b2 in a ratio [b1:b2] of 92%:8% to 70%:30% obtained by the area percentage method using liquid chromatography (hereinafter also referred to as "first flame retardant component").

[0055] [Chemistry 3]

[0056]

[0057] [In the formula, R] 1 and R 2 The same or different characters represent hydrogen or alkyl groups having 1 to 3 carbon atoms that may have substituents; m and n represent integers from 0 to 2 that may be the same or different.

[0058] The first flame retardant component is composed of a mixture of the above-mentioned bisphenol S derivatives, particularly derivatives with an m+n of 4 (i.e., substances with a total of 4 bromines substituted on the phenyl group; hereinafter referred to as "tetrasubstituted products") and derivatives with an m+n of 0 to 3 (i.e., substances with a total of 0 to 3 bromines substituted on the phenyl group; hereinafter referred to as "non-tetrasubstituted products"). Furthermore, the mixing ratio of the above-mentioned tetrasubstituted products to non-tetrasubstituted products in the mixture is 92%:8% to 70%:30%. Within this mixing ratio range, superior bloom suppression effect and heat resistance can be obtained.

[0059] The above mixing ratio is based on the area percentage method obtained using liquid chromatography. That is, the total area of ​​the peaks detected in the chromatogram is set as 100%, and the ratio of the total peak area of ​​the tetrasubstituted products to the total peak area of ​​the non-tetrasubstituted products is calculated and quantified.

[0060] The apparatus and operating conditions for the liquid chromatography method used in this invention are as follows.

[0061] a) Apparatus used: ACQUITY UPLC H-Class; Column: ACQUITY UPLC BEH C 18 1.7μm, inner diameter 2.1mm × length 100mm (manufactured by Waters Corporation)

[0062] b) Flow rate: 0.35 mL / min

[0063] c) Column temperature: 40℃

[0064] d) Analysis time: 9 minutes

[0065] e) Linear gradient of mobile phase: acetonitrile / 0.1% formic acid aqueous solution mixture (50%:50% v / v) → acetonitrile / 0.1% formic acid aqueous solution mixture (95%:5% v / v) (5.5 min) → acetonitrile / 0.1% formic acid aqueous solution mixture (95%:5% v / v) (9 min)

[0066] f) Measurement wavelength: UV 210~410nm (analytical UV 254nm).

[0067] In the above general formula (1), R 1 and R 2 The same or different means represent hydrogen or alkyl groups having 1 to 3 carbon atoms that may have substituents.

[0068] Examples of substituents mentioned above include halogen groups and hydroxyl groups. While there are no particular limitations on the alkyl group having 1 to 3 carbon atoms that may have the substituent, bromo-substituted propyl is preferred. Furthermore, bromo-substituted propyl is acceptable as long as at least one of the substituents is bromine, and is not limited to all substituents being bromine. 2,3-dibromopropyl or 2-hydroxy-3-bromopropyl is particularly preferred as such bromo-substituted propyl.

[0069] In the above general formula (1), m and n represent integers from 0 to 2, either the same or different. In the case where m+n is 4 (tetrasubstituted), each phenyl group is substituted with 2 (totaling 4) bromine atoms. Suitable examples of tetrasubstituted compounds are shown below.

[0070] [Chemistry 4]

[0071]

[0072] Furthermore, in the case where m+n is 0 to 3 (non-tetrasubstituted), the total number of bromine atoms substituted on the phenyl group is 3 or less. Specifically, non-tetrasubstituted products can be classified into "trisubstituted products" with m+n of 3, "disubstituted products" with m+n of 2, "monosubstituted products" with m+n of 1, and "zero-substituted products" with m+n of 0. Specific examples of trisubstituted, disubstituted, monosubstituted, and zero-substituted products will be revealed in turn.

[0073] Examples of trisubstituted substances include the following.

[0074] [Chemistry 5]

[0075]

[0076] Examples of disubstituted substances include the following.

[0077] [Chemistry 6]

[0078]

[0079] Examples of substances that are monosubstituted are the following.

[0080] [Chemistry 7]

[0081]

[0082] Examples of substances that are zero-substituted are the following.

[0083] [Chemistry 8]

[0084]

[0085] As mentioned earlier, the first flame-retardant component is essentially a mixture of 70-92% tetrasubstituted and 8-30% non-tetrasubstituted. The proportions are not limited as long as they are within the relevant range, but a tetrasubstituted:non-tetrasubstituted ratio of 92% : 8% to 75% : 25% is particularly preferred. When the proportion of tetrasubstituted exceeds 92%, there is a risk that blooming cannot be adequately suppressed after compounding with polyolefin resins. When the proportion of tetrasubstituted is less than 70%, there is a risk of deterioration in heat resistance.

[0086] The first flame retardant component itself can be a known or commercially available substance. Alternatively, a substance manufactured according to a known manufacturing method can be used. For example, it can be suitably manufactured using the method described in Japanese Patent No. 4817726.

[0087] The content of the first flame-retardant component is typically 2 to 50 parts by weight relative to 100 parts by weight of polypropylene resin, particularly preferably 3 to 20 parts by weight, and even more preferably 4 to 15 parts by weight. By setting it within the above range, excellent flame retardancy, bloom suppression effect, and heat resistance can be obtained.

[0088] (C) Second flame retardant component

[0089] 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 is used (hereinafter also referred to as "the second flame retardant component"). By having the first flame retardant component and the second flame retardant component coexist in the composition of the present invention, both high bleed suppression effect and excellent heat resistance can be obtained simultaneously.

[0090] From the perspective of the effects described above, the content of the second flame retardant component is usually 0.2 to 20 parts by weight, and particularly preferably 0.5 to 15 parts by weight, relative to 100 parts by weight of polypropylene resin.

[0091] Meanwhile, the weight ratio of the first flame retardant component to the second flame retardant component is not limited, but when the total weight of the two is set to 100% by weight, a ratio of 40% by weight of the first flame retardant component to 60% by weight to 90% by weight of the second flame retardant component is particularly preferred. By using the two components together in such a weight ratio, the composition of the present invention can be given a more superior exudation inhibition effect and heat resistance.

[0092] (D) Flame retardant additives

[0093] The composition of this invention comprises at least one selected from antimony trioxide, antimony pentoxide, zinc molybdate, boron trioxide, and zinc borate (hereinafter also referred to as "flame retardant additive"). When these flame retardant additives are included, better flame retardant properties are achieved. Of the above, at least one of antimony trioxide and antimony pentoxide is preferred, and antimony trioxide is particularly preferred from the viewpoint of imparting high flame retardancy. Meanwhile, the form of the flame retardant additive is not particularly limited, and substances in powder form, for example, can be used. These flame retardant additives can be known or commercially available substances.

[0094] Relative to 100 parts by weight of polypropylene resin, the content of flame retardant additive in the composition of the present invention is typically set to 1-20 parts by weight, and particularly preferably 2-15 parts by weight. This results in high flame retardancy while also achieving high exudation inhibition and excellent heat resistance.

[0095] (E) Other additives

[0096] In the compositions of the present invention, various additives known or commercially available resin compositions or their molded articles may be added as needed, without impairing the effects of the present invention. Examples of additives include, in addition to resin components other than polypropylene resins, dispersants, surfactants, weather stabilizers, antioxidants, ultraviolet absorbers, antifogging agents, antistatic agents, antibacterial agents, impact resistant agents, foaming agents, fillers, conductive powders, nucleating agents, crosslinking agents, colorants, lubricants, etc.

[0097] (2) Properties of the composition of the present invention

[0098] The properties of the composition of the present invention are not particularly limited. It can be a solid (powder) at room temperature and pressure, and a molten state when heated. Furthermore, it can also be a solidified form of the molten material. Moreover, it can also be a liquid obtained by dissolving or dispersing the above-mentioned solid in a solvent as required.

[0099] (3) Modification of the composition of the present invention

[0100] The method for preparing the composition of the present invention is not particularly limited as long as it can uniformly mix the components. Alternatively, it can be a method of obtaining an unformed, unmelted mixture (powder) by mixing the components, or a method of obtaining a solid by melting and then solidifying it. For example, a method can be used to pre-mix the components constituting the composition of the present invention using a mixer such as a Henschel mixer, a drum mixer, or a rotor mixer, and then feed it to a mixing mill heated to the melting temperature of a polypropylene resin, thereby obtaining resin composition particles.

[0101] Alternatively, the components can be fed separately to the mixer via a metering feeder without prior mixing (premixing). Alternatively, the components (e.g., the first flame retardant component, the second flame retardant component, flame retardant additives, etc.) and the polypropylene resin can be fed separately to the mixer via a metering feeder.

[0102] 2. Molded body

[0103] The present invention also includes molded articles formed by molding the compositions of the present invention. In this case, the size, shape, etc. of the molded article can be appropriately set according to the purpose and usage of the molded article.

[0104] As for the forming method, there are no particular limitations as long as it can form the melt of the composition of the present invention, the sheet form of the composition of the present invention, etc., and various forming methods such as press forming, injection molding, extrusion molding, blow molding, and vacuum forming can be used. Therefore, known or commercially available forming equipment such as heated compression molding machines and injection molding machines can be used.

[0105] The applications of the molded articles of this invention are not particularly limited to any articles that require at least flame retardancy. Examples include parts and covers for washing machines, refrigerators, dish dryers, rice cookers, electric fans, televisions, personal computers, audio equipment, microwave ovens, heated toilets, irons, etc.; circuit boards for electronic machines such as mobile phones, personal computers, printers, and fax machines; parts and covers for air conditioners, heaters, stoves, hot air blowers, water heaters, etc.; and parts and interior materials for building materials, automobiles, ships, aircraft, etc.

[0106] Example

[0107] The present invention will be further described below by way of examples and comparative examples. However, the present invention is not limited to these examples.

[0108] 1. Regarding starting materials

[0109] (A) Polypropylene resin

[0110] As the polypropylene resin, commercially available polypropylene resin (product name "Prime Polypro J707G", (MFR: 30g / 10min, block-PP), manufactured by PRIME POLYMER (PP)) is used.

[0111] (B) First flame retardant component

[0112] The first flame retardant component is manufactured using the following method.

[0113] Manufacturing Example 1 (Article of the Invention)

[0114] Prepare a glass reaction vessel equipped with a stirrer, condenser, thermometer, dropping funnel, and heating and cooling devices. Add 1000g of water and 250g (1 mol) of bisphenol S to the reaction vessel. While stirring the contents, add 591g (3.7 mol) of bromine dropwise over 2 hours to bromine-substituted phenyl groups. The dropwise addition causes the temperature of the contents to rise from 5°C to 40°C. After the addition is complete, allow the reaction to continue for another hour. The reaction solution is reddish due to the free bromine, so sodium sulfite (reducing agent) is added until the red color disappears. Then, allow another hour to complete the reduction reaction. In Example 1, the amount of bromine is set to 591g because the weight ratio of the tetrasubstituted product to the non-tetrasubstituted product after the substitution reaction is set to approximately 9:1.

[0115] Next, 464 g of a 50% sodium hydroxide aqueous solution (5.8 mol of sodium hydroxide) was added to the reaction solution over 30 minutes. The pH of the reaction solution after addition was above 9. The addition caused the temperature of the reaction solution to rise from 5°C to 40°C. This addition was carried out to neutralize the hydrogen bromide produced by the substitution reaction and to convert the bromosubstituted bisphenol S into a water-soluble alkali metal salt (Na salt). Then, 400 g of isopropanol (IPA) (boiling point 82.5°C) and 187.4 g (2.45 mol) of allyl chloride were added to the reaction solution and refluxed. Reflux caused the temperature of the solution to rise from 40°C to 83°C. This operation was to etherify the bromosubstituted bisphenol S allyl group. Furthermore, when the pH of the reaction solution became acidic, an aqueous sodium hydroxide solution was added until it became alkaline. The endpoint of the reaction was determined according to the following description. That is, the endpoint was defined as the point at which a small amount of the reaction solution was taken out and no white or milky white color appeared after adding an aqueous hydrochloric acid solution. In Manufacturing Example 1, it took 8 hours to reach the point where no white or milky white color appeared. After the reaction was completed, needle-like crystals of diallyl ether were formed in the reaction vessel.

[0116] Next, after removing the liquid components from the reaction vessel, water is added to the vessel to wash the container and reaction product, dissolving and removing unwanted alkali salts, IPA, allyl chloride, etc. The reaction product is then transferred to a ceramic filter, and 1000 ml of water is added to completely dissolve and remove unwanted alkali salts, IPA, allyl chloride, etc. The washed reaction product is transferred to a 2-liter glass flask, which is then connected to an evaporator for hot water (60°C) and dried under reduced pressure at 20 torr. A glass reaction vessel equipped with a stirrer, condenser, thermometer, dropping funnel, and heating and cooling devices is prepared. The dried reaction product is placed in the reaction vessel, and 600 g of dichloromethane (solvent) is added to completely dissolve it. Two moles of bromine are added dropwise to the solution using a dropping funnel. This addition results in bromine addition to the unsaturated allyl bonds of the bromine-substituted bisphenol S derivative. Because the reaction is accompanied by intense heating, thorough stirring and cooling are essential. The liquid temperature during the reaction is controlled to not exceed 40°C. The endpoint of the bromine addition reaction is set at the point when the reaction solution retains a reddish hue after a specific amount of bromine has been added dropwise. In Manufacturing Example 1, the reaction takes 2 hours from the start of bromine addition.

[0117] Afterwards, the reaction was continued for another hour for post-curing. Then, 1000 ml of water was added to the reaction solution, and the mixture was vigorously stirred to dissolve the unwanted unreacted bromine in the aqueous phase. The aqueous phase was repeatedly decanted to remove the bromine. Next, the reaction product was added to 2000 ml of methanol under vigorous stirring for 5 minutes to allow it to precipitate again. The precipitate was crushed and then allowed to stand in methanol for 10 hours to crystallize. After removing most of the methanol by filtration, the product was transferred to a 2000 ml glass flask. The flask was connected to an evaporator for hot water (70°C), and unwanted solvents (methanol, water, etc.) were distilled off under a reduced pressure of 10 Torr. The yield of the reaction product (bromine-based flame retardant) was 745 g.

[0118] The area percentage of the tetrasubstituted to non-tetrasubstituted products was identified by liquid chromatography, yielding a ratio of 89:11. Simultaneously, the melting endothermic peak temperature of the reaction products was determined using differential scanning pyrolysis, confirming a melting point peak at 122℃. The chemical formula of the obtained reaction products is shown below.

[0119] [Chemistry 9]

[0120]

[0121] Manufacturing Example 2 (Article of the Invention)

[0122] Except that 559.3 g (3.5 mol) of bromine was added to bisphenol S, and the amount of 50% sodium hydroxide aqueous solution added for the allyl etherification reaction was set to 448 g (as 5.6 mol of sodium hydroxide), the process was carried out in the same manner as in Manufacturing Example 1, and the brominated flame retardant was obtained. The yield of the reaction product (bromine-based flame retardant) was 711 g.

[0123] The area percentage of the tetrasubstituted to non-tetrasubstituted products was identified by liquid chromatography, yielding a ratio of 73:27. Simultaneously, the melting endothermic peak temperature of the reaction products was determined using differential scanning pyrolysis, confirming a melting point peak at 105 °C. The chemical formula of the obtained reaction products is shown below.

[0124] [Chemistry 10]

[0125]

[0126] Manufacturing Example 3 (Comparative Article)

[0127] In addition to using tetrabromobisphenol S (TBS, trade name EB400S, manufactured by Manac Inc.) containing more than 95% by weight of bromosubstituted bisphenol S (tetrasubstituted bisphenol S with a 4-fold bromine substitution) as the starting material for allyl etherification, and dissolving 412 g (4 moles) of sodium bromide as a catalyst for the allyl etherification reaction in the reaction solution, the reaction was carried out in the same manner as in Example 1 to obtain a brominated flame retardant. The yield of the reaction product (bromoinated flame retardant) was 765 g.

[0128] The area percentage of the tetrasubstituted to non-tetrasubstituted products was identified by liquid chromatography, with a result of 99:1. Simultaneously, the melting endothermic peak temperature of the reaction products was determined using differential scanning pyrolysis, confirming a melting point peak at 120℃. The chemical formula of the obtained reaction products is shown below.

[0129] [Chemistry 11]

[0130]

[0131] Manufacturing Example 4 (Comparative Article)

[0132] Except that 527.3 g (3.3 mol) of bromine was added to bisphenol S, and the amount of 50% sodium hydroxide aqueous solution added for the allyl etherification reaction was set to 432 g (as 5.4 mol of sodium hydroxide), the process was carried out in the same manner as in Manufacturing Example 1, and a brominated flame retardant was obtained. The yield of the reaction product (bromine-based flame retardant) was 670 g.

[0133] The area percentage of the tetrasubstituted to non-tetrasubstituted products was identified by liquid chromatography, yielding a ratio of 65:35. Simultaneously, the melting endothermic peak temperature of the reaction products was determined using differential scanning pyrolysis, confirming a melting point peak at 98℃. The chemical formula of the obtained reaction products is shown below.

[0134] [Chemistry 12]

[0135]

[0136] (C) Second flame retardant component

[0137] The following commercially available products are used as the second flame retardant component.

[0138] • Product name: “PyroguardSR 720” (Tetrabromobisphenol A bis(2,3-dibromopropyl ether), manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd. (hereinafter referred to as “TBA-DBP”)

[0139] • Product name "TAIC-6B" (tris(2,3-dibromopropyl)isocyanurate), manufactured by Nippon Chemical Industries (hereinafter referred to as "TBIC").

[0140] (D) Flame retardant additives

[0141] As a flame retardant additive, antimony trioxide powder (average particle size 3 μm) is used.

[0142] 2. Regarding the resin composition

[0143] Examples 1-6 and Comparative Examples 1-10

[0144] The components shown in 1. are dry-mixed according to the proportions shown in Tables 1 and 2, and extruded and mixed at a temperature of 200-210°C using a twin-shaft mixer "KTX30" (manufactured by Kobe Steel Co., Ltd.), and cut into strips to obtain a granular flame-retardant resin composition.

[0145] The obtained granules were molded using an injection molding machine (manufactured by Nissei Resin Industries, Ltd., FE80S 18ASE, barrel temperature 200°C, mold temperature 40°C) to produce vertical burning test specimens (127mm × 12.7mm, thickness: 1 / 32 inch) as specified in UL94.

[0146] Similarly, a bloom evaluation plate (35mm × 48mm × 1.5mm thick) was produced by injection molding machine (manufactured by Nissei Resin Industries, Ltd., FE80S18ASE, barrel temperature 200℃, mold temperature 40℃).

[0147] Experimental Example 1

[0148] The following physical properties were tested using the samples prepared in each of the examples and comparative examples. The results are shown together in Table 1.

[0149] (1) Flammability

[0150] The flammability evaluation of the resin composition is based on the Underwriters Laboratories' safety standard "UL-94 Flammability Test," using the aforementioned vertical flammability test piece. The UL-94 flammability test is broadly divided into two types: horizontal testing (HB method) and vertical testing (V method). The overall flammability evaluation shows that flame retardancy increases in the order FAIL < HB < V-2 < V-1 < V-0. V-0 represents the highest flame retardancy.

[0151] (2) Frosting properties

[0152] The blooming test plate was heated at 80°C for 48 hours, and the difference in gloss before and after the test (gloss difference) was measured using a Horiba Seisakusho IG-320 gloss meter at a measurement angle of 60°. Blooming of flame retardants can cause efflorescence on the surface of molded articles, resulting in reduced gloss. Generally, a gloss difference of 20 or more is observed when efflorescence is visible to the naked eye. Therefore, a gloss difference of less than 20 is considered "no blooming," and a gloss difference of 20 or more is considered "blooming."

[0153] (3) Heat resistance

[0154] During molding and processing, the decomposition of brominated flame retardants generates highly toxic acrolein, halogenated compounds, and other decomposition products, which are released into the operating environment. To simulate this heating condition during molding and processing, 0.1 g of a brominated flame retardant (or the combined amount of the first and second flame retardants if a second flame retardant is present) was heated at 230°C for 15 minutes in a sealed container. The concentration of total volatile organic compounds (TVOC) was then determined using a headspace sampler gas chromatography-mass spectrometer manufactured by Agilent Technologies. For brominated flame retardants, a TVOC level above 1 ppm was considered "poor heat resistance," while a level below 1 ppm was considered "good heat resistance."

[0155] [Table 1]

[0156]

[0157] [Table 2]

[0158]

[0159] The results in Tables 1 and 2 clearly show that the molded articles of the present invention exhibit excellent flame retardancy without blooming and maintain a superior appearance. Furthermore, because the TVOC value is less than 1 ppm (especially below 0.70 ppm), it is evident that gases generated during molding (odorous and harmful gases) can be effectively suppressed (i.e., excellent heat resistance).

[0160] In contrast, it can be seen that the molded articles of the comparative examples have problems in at least one aspect of blooming or heat resistance.

[0161] More specifically, as shown in Table 2, Comparative Example 1 shows that although the mixing ratio of tetrasubstituted and non-tetrasubstituted products is within the range of the present invention, the TVOC value is higher compared to Example 4, which uses both the first and second flame retardant components, because it does not contain the second flame retardant component. Similarly, Comparative Example 2 shows that although the mixing ratio of tetrasubstituted and non-tetrasubstituted products is within the range of the present invention, the TVOC value is higher compared to Example 5 or Example 6, which uses both the first and second flame retardant components, because it does not contain the second flame retardant component.

[0162] As can be seen from Comparative Example 3, although the first flame retardant component, which contains 10 parts by weight of a mixture of a tetrasubstituted and a non-tetrasubstituted component in a ratio of 99:1, suppresses the generation of gas and imparts a high flame retardancy rating of V-0, blooming occurs, and the appearance of the molded article deteriorates significantly. Therefore, the tetrasubstituted component does not have the effect of suppressing blooming.

[0163] As can be seen from Comparative Example 4, although the first flame retardant component, which contains 10 parts by weight of a mixture of tetrasubstituted and non-tetrasubstituted components in a ratio of 65:35, has a relatively high content of non-tetrasubstituted components, thus imparting high flame retardancy and maintaining excellent appearance, it also has poor heat resistance and generates gas during processing due to the large amount of non-tetrasubstituted components.

[0164] As can be seen from Comparative Examples 5 and 6, although each of TBA-DBP and TBIC, which are the second flame retardant components, are formulated with 10 parts by weight respectively, thus imparting high flame retardancy and suppressing gas generation, blooming occurs because the first flame retardant component is not present at all, and the appearance of the molded product is significantly deteriorated.

[0165] As can be seen from Comparative Example 7, although the mixture containing 10 parts by weight of the first flame retardant component containing 1% non-tetrasubstituted and TBA-DBP as the second flame retardant component in a 9:1 ratio suppresses gas generation and imparts high flame retardancy, blooming occurs due to the low content of non-tetrasubstituted, and the appearance of the molded article is significantly deteriorated.

[0166] As can be seen from Comparative Example 8, although the mixture containing 10 parts by weight of the first flame retardant component containing 35% non-tetrasubstituted derivatives and TBA-DBP as the second flame retardant component mixed in a 9:1 ratio imparts high flame retardancy and maintains excellent appearance, it has poor heat resistance and generates gas during processing.

[0167] As can be seen from Comparative Example 9, although the first flame retardant component and the second flame retardant component were used together, the mixing ratio of the tetrasubstituted and non-tetrasubstituted components in the first flame retardant component was 99:1, so blooming occurred and the appearance of the molded article was significantly deteriorated.

[0168] As can be seen from Comparative Example 10, the first flame retardant component, which uses a mixture of tetrasubstituted and non-tetrasubstituted components in a ratio of 65:35 and has a relatively high content of non-tetrasubstituted components, has poor heat resistance and generates gas during processing.

Claims

1. A flame-retardant polypropylene resin composition, characterized in that, contains the following components (A) to (D): (A) polypropylene-based resin: 100 parts by weight; (B) bisphenol S derivative represented by the following general formula (1) which is a mixture of the derivative bl in which m + n is 4 and the derivative b2 in which m + n is 0 to 3, and which is a mixture in which the ratio of bl to b2, i.e., bl : b2, is 92% : 8% to 70% : 30% according to an area percentage method using liquid chromatography: 2 parts by weight to 50 parts by weight wherein R 1 and R 2 each independently represent hydrogen or an optionally substituted C1-3 alkyl group; m and n each independently represent an integer of 0-2; and X represents a halogen atom or a hydrogen atom. wherein R 1 and R 2 each independently represent hydrogen or an optionally substituted C1-3 alkyl group; m and n each independently represent an integer of 0-2; and X represents a halogen atom or a hydrogen atom. wherein R 1 and R (C) at least one of (cl) tetrabromobisphenol A bis(2,3-dibromopropyl) ether and (c2) tris(2,3-dibromopropyl) isocyanurate: 0.2 parts by weight to 20 parts by weight; and (D) at least one of antimony trioxide, antimony pentoxide, zinc molybdate, boron trioxide, and zinc borate: 1 part by weight to 20 parts by weight, the (B) component and the (C) component are contained in the composition in a ratio of the (B) component : the (C) component = 40% by weight : 60% by weight to 90% by weight : 10% by weight, when the total amount of both is taken as 100% by weight.

2. The flame-retardant polypropylene resin composition according to claim 1, wherein, R 1 and R 2 are each, identically or differently, a bromo-substituted propyl group.

3. The flame-retardant polypropylene resin composition according to claim 1 or 2, wherein, R 1 and R 2 are the same or different from each other and are 2,3-dibromopropyl or 2-hydroxy-3-bromopropyl.

4. A shaped body which is shaped from the flame-retardant polypropylene-based resin composition described in any one of claims 1 to 3.

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