Polypropylene-based resin composition

Abstract

To provide a flame-retardant polypropylene-based resin composition which uses a smaller addition amount of a phosphorus-based flame retardant and has a low specific gravity.SOLUTION: A propylene-based resin composition contains a polypropylene-based resin (A) satisfying a requirement (A1), an additive (B) satisfying a requirement (B1), and a flame retardant (C) satisfying a requirement (C1), and satisfies Condition 1.

Description

[Technical Field]

[0001] The present invention relates to a polypropylene resin composition, and more particularly to a flame-retardant polypropylene resin composition having a low specific gravity and containing a phosphorus-based flame retardant in a reduced amount. [Background technology]

[0002] Taking advantage of their superior chemical and mechanical properties, polyolefin resins are widely used in a variety of fields, including building materials, automobile parts, packaging materials, and home appliances, and their applications are expanding. However, many polyolefin resins are flammable, and flame retardancy is required for some applications. A widely used flame retardant method has traditionally been a combination of a bromine-based flame retardant and antimony trioxide, a flame retardant promoter.

[0003] However, resin compositions to which this flame retardant technique is applied have been criticized for generating halogen-based gases during combustion, molding, etc. Therefore, there is a demand for flame-retardant resin compositions that do not generate halogen-based gases during combustion, molding, etc., and one candidate is a resin composition that uses a phosphorus-based flame retardant.

[0004] Phosphorus-based flame retardants are generally known to be clean materials that emit fewer harmful gases than bromine-based flame retardants, but on the other hand, there is the problem that a large amount needs to be added to achieve flame retardancy, resulting in a high specific gravity. Studies have been conducted to achieve higher flame retardancy with lower additive amounts than conventionally used. For example, Patent Document 1 describes a phosphorus-based flame retardant that can achieve flame retardancy with a relatively low additive amount. Furthermore, Patent Document 2 adds dipentaerythritol, a polyhydric alcohol, to improve flame retardancy. The mechanism by which this flame retardancy is achieved is discussed in Non-Patent Document 1, which also suggests the mechanism by which performance is improved by adding a "polyhydric alcohol." Furthermore, Patent Document 3 aims to improve flame retardancy by using glycerin monostearate as a flame retardant aid.

[0005] However, even with the technology disclosed in Patent Document 1, the amount added is still not sufficiently small, and materials using phosphorus-based flame retardants have not been accepted in the market due to their high specific gravity. Furthermore, while the technology disclosed in Patent Document 2 shows improvements in flame retardancy, the disclosed polyhydric alcohol has drawbacks such as being difficult to mix with polyolefin resins and having low thermal stability. Furthermore, the technology using glycerin monostearate disclosed in Patent Document 3 raises concerns about the generation of harmful acrolein from glycerin monostearate when heated during molding or combustion, so there has been a demand for a technology that provides higher flame retardancy and is safer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-026935 [Patent Document 2] International Publication No. 2014-097967 Brochure [Patent Document 3] Japanese Patent Application Publication No. 2019-85551

[0007] [Non-Patent Document 1] “Carbonization mechanisms resulting from intumescence association with the ammonium polyphosphate-pentaerythritol fire retardant system”(Carbon, Volume 31, Issue 8, 1993, Pages 1219-1230) DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0008] In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a flame-retardant polypropylene resin composition having a low specific gravity and using a phosphorus-based flame retardant in a lower amount. [Means for solving the problem]

[0009] As a result of extensive research conducted to solve the above-mentioned problems, the present inventors have found that a polypropylene-based resin composition obtained by blending a specific additive and a flame retardant in a specific ratio with a polypropylene-based resin can solve the above-mentioned problems, and have completed the present invention based on these findings.

[0010] That is, the present invention has the following configuration. [1] A propylene-based resin composition comprising a polypropylene-based resin (A) that satisfies the following requirement (A1), an additive (B) that satisfies the following requirement (B1), and a flame retardant (C) that satisfies the following requirement (C1), and characterized by satisfying the following condition 1: Requirement (A1) The polypropylene resin (A) contains at least one propylene polymer selected from the group consisting of propylene homopolymers, propylene random copolymers, and propylene block copolymers. Requirement (B1) The additive (B) has a carboxy group or a structure that serves as a precursor of a carboxy group in its molecular structure (however, this does not include structures in which the structure that serves as a precursor of a carboxy group generates a lower polyhydric alcohol when a carboxy group is generated). Requirement (C1) The flame retardant (C) is an organic flame retardant. Condition 1 The propylene-based resin composition contains 78.5 to 86.7 wt % of a polypropylene-based resin (A), 0.3 to 1.5 wt % of an additive (B), and 13 to 20 wt % of a flame retardant (C) (wherein the total of the polypropylene-based resin (A), the additive (B), and the flame retardant (C) is 100 wt %). [2] The propylene-based resin composition according to [1], wherein the precursor of the carboxy group of the additive (B) is at least one selected from the group consisting of carboxylic acid esters, carboxylic acid amides, and carboxylic acid anhydrides. [3] The propylene-based resin composition according to [1] or [2], wherein the flame retardant (C) is a phosphorus-based flame retardant. [4] A molded article obtained from the propylene-based resin composition according to any one of [1] to [3]. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a flame-retardant polypropylene resin composition having a low specific gravity by using a lower amount of a phosphorus-based flame retardant.

[0012] The present invention relates to a propylene-based resin composition comprising a polypropylene-based resin (A) that satisfies the following requirement (A1), an additive (B) that satisfies the following requirement (B1), and a flame retardant (C) that satisfies the following requirement (C1), and characterized by satisfying the following condition 1: Requirement (A1) The polypropylene resin (A) contains at least one propylene polymer selected from the group consisting of propylene homopolymers, propylene random copolymers, and propylene block copolymers. Requirement (B1) The additive (B) has a carboxy group or a structure that serves as a precursor of a carboxy group in its molecular structure (however, this does not include structures in which the structure that serves as a precursor of a carboxy group generates a lower polyhydric alcohol when a carboxy group is generated). Requirement (C1) The flame retardant (C) is an organic flame retardant. Condition 1 The propylene-based resin composition contains 78.5 to 86.7 wt % of a polypropylene-based resin (A), 0.3 to 1.5 wt % of an additive (B), and 13 to 20 wt % of a flame retardant (C) (wherein the total of the polypropylene-based resin (A), the additive (B), and the flame retardant (C) is 100 wt %).

[0013] Each item of the propylene-based resin composition of the present invention will be described in detail below.

[0014] 1. Propylene-based resin composition The propylene-based resin composition of the present invention satisfies the following condition 1.

[0015] Condition 1 The propylene resin composition contains 78.5 to 86.7 wt% of a polypropylene resin (A), 0.3 to 1.5 wt% of an additive (B), and 13 to 20 wt% of a flame retardant (C) (wherein the total of the polypropylene resin (A), the additive (B), and the flame retardant (C) is 100 wt%). Details of the polypropylene resin (A), the additive (B), and the flame retardant (C) will be described later.

[0016] The propylene resin composition must contain 78.5 to 86.7 wt%, preferably 79.7 to 86.1 wt%, more preferably 80.9 to 85.5 wt%, and more preferably 82.1 to 84.9 wt% of polypropylene resin (A). The additive (B) must be contained in an amount of 0.3 to 1.5 wt%, preferably 0.4 to 1.3 wt%, more preferably 0.5 to 1.1 wt%, and more preferably 0.6 to 0.9 wt%. The flame retardant (C) must be contained in an amount of 13 to 20 wt%, preferably 13.5 to 19 wt%, more preferably 14 to 18 wt%, and more preferably 14.5 to 17 wt%. By setting the contents of the polypropylene-based resin (A), the additive (B), and the flame retardant (C) within these ranges, it is possible to ensure sufficient flame retardancy without using a large amount of the flame retardant (C), which has a higher specific gravity than the polypropylene-based resin (A). This makes it possible to provide a material that exhibits sufficient flame retardancy while maintaining a relatively low specific gravity.

[0017] That is, the specific gravity of the propylene-based resin composition of the present invention is usually 0.93 to 1.0 g / cm 3 , preferably 0.95 to 0.99 g / cm 3 , more preferably 0.96 to 0.98 g / cm 3 is. The specific gravity of a typical propylene resin is approximately 0.9 g / cm 3 Therefore, when the specific gravity of the propylene-based resin composition is in the above range, the increase rate of the specific gravity of the propylene-based resin composition relative to the specific gravity of the base propylene resin can be kept to about 10%, preferably within 10%, making it possible to provide a lighter, more flame-retardant material.

[0018] (1) Polypropylene resin (A) The polypropylene resin (A) used in the present invention will be described in detail below.

[0019] Requirement (A1) The polypropylene resin (A) used in the present invention contains at least one propylene polymer selected from the group consisting of propylene homopolymers, propylene random copolymers, and propylene block copolymers. The propylene random copolymer is preferably a propylene-α-olefin random copolymer. Furthermore, the propylene block copolymer is preferably a propylene-α-olefin block copolymer. Hereinafter, in this specification, the propylene-α-olefin block copolymer and the propylene-α-olefin random copolymer may be simply referred to as "propylene-α-olefin copolymer." The propylene-α-olefin copolymer preferably used is a copolymer containing propylene and an α-olefin other than propylene having 2 to 8 carbon atoms as a comonomer, a random copolymer or block copolymer of propylene and an α-olefin having a propylene content of 70 to 99.99% by weight (i.e., a comonomer content of 0.01 to 30% by weight), more preferably a random copolymer or block copolymer of propylene and an α-olefin having a propylene content of 90% by weight or more. Also, it may be a mixture of random copolymers or block copolymers containing different α-olefins.

[0020] The comonomer, which is an α-olefin having 2 to 8 carbon atoms other than propylene and is copolymerized with propylene, may be used alone or in combination of two or more. Specific examples of the propylene-α-olefin copolymer include binary copolymers such as propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-pentene-1 copolymer, propylene-hexene-1 copolymer, and propylene-octene-1 copolymer, and ternary copolymers such as propylene-ethylene-butene-1 copolymer and propylene-ethylene-hexene-1 copolymer, with propylene-ethylene random copolymer and propylene-ethylene-butene-1 random copolymer being preferred. The content of the α-olefin monomer in the propylene-α-olefin copolymer is usually about 0.01 to 30% by weight, preferably 1 to 20% by weight, and more preferably about 1 to 10% by weight.

[0021] Examples of the α-olefins having 2 to 8 carbon atoms other than propylene include ethylene, 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, and 1-octene.

[0022] From the viewpoint of moldability, the polypropylene resin (A) preferably has a melting point of 100 to 170°C, more preferably 150 to 165°C. The melting point of the polypropylene resin can be appropriately controlled mainly by the types of propylene and α-olefins other than propylene used as raw materials, the copolymerization ratio, the melt flow rate (MFR), etc. The "melting point" referred to in this specification is the melting peak temperature measured by a differential scanning calorimeter (DSC).

[0023] The polypropylene resin (A) used in the present invention preferably has a melt flow rate (MFR) according to JIS K7210 [measurement temperature: 230°C, load: 2.16 kg (21.18 N)] of 1.0 to 200 g / 10 min, more preferably 5.0 to 150 g / 10 min, and even more preferably 10 to 100 g / 10 min. By setting the MFR within this range, the propylene resin composition of the present invention and the molded article obtained by molding it can maintain good flame retardancy and moldability while exhibiting good scratch resistance and flexural strength. That is, if the MFR is less than 1 g / 10 min, the load during molding of the propylene resin composition of the present invention increases, resulting in poor moldability and the risk of discoloration of the molded article and a poor appearance. Conversely, if the MFR is greater than 200 g / 10 min, the scratch resistance and flexural strength may be impaired. When the polypropylene-based resin (A) contains two or more types of propylene polymers, all of these two or more types of propylene polymers may have a melt flow rate (MFR) within the above-mentioned range, or some or all of the two or more types of propylene polymers may have a melt flow rate (MFR) outside the above-mentioned range, but the polypropylene-based resin (A) as a whole may have a melt flow rate (MFR) within the above-mentioned range.

[0024] Furthermore, the polypropylene resin (A) preferably used in the present invention has an isotactic pentad fraction (mmmm fraction), which indicates the degree of crystallinity, of 96% or more, and more preferably an isotactic pentad fraction of 97% or more. An isotactic pentad fraction of 96% or more is preferred because it provides good scratch resistance and bending strength. This is due to the effect of the crystal orientation of the polypropylene resin (A) on the surface layer of the molded article. The degree of crystallinity of the polypropylene resin (A) can be controlled by adjusting the copolymerization ratio of the raw materials and the molecular weight distribution by using the catalyst used. The isotactic pentad fraction (mmmm) is 13It is a value measured using C-NMR (nuclear magnetic resonance method), and is a nuclear magnetic resonance spectrum ( 13 The isotactic pentad fraction is the isotactic fraction of pentad units in a polypropylene molecular chain measured using C-NMR. That is, the isotactic pentad fraction is the fraction of propylene units in which five consecutive propylene monomer units are isotactically bonded. Specifically, 13 The isotactic pentad unit is measured by the intensity fraction of the mmmm peak among all absorption peaks in the methyl carbon region of the C-NMR spectrum, and for example, a 270 MHz FT-NMR device manufactured by JEOL Ltd. is used.

[0025] The catalyst used to obtain the polypropylene resin (A) used in the present invention is not particularly limited, and known catalysts can be used. For example, so-called Ziegler-Natta catalysts, which combine a titanium compound and an organoaluminum compound (e.g., as described in Polypropylene Handbook (first edition, first printing published May 15, 1998)), or metallocene catalysts (e.g., as described in JP-A-5-295022) can be used.

[0026] The polymerization process used to obtain the polypropylene resin (A) used in the present invention is not particularly limited, and any known polymerization process can be used. For example, a slurry polymerization method, a bulk polymerization method, a gas phase polymerization method, etc. can be used. Furthermore, either a batch polymerization method or a continuous polymerization method can be used, and if desired, a multi-stage continuous polymerization method such as a two-stage or three-stage method can also be used. Furthermore, the polypropylene resin (A) can also be produced by mechanically melt-kneading two or more types of propylene polymers. Various polypropylene resins that can be used as the polypropylene-based resin (A) are commercially available from many companies, such as the Novatec series manufactured by Japan Polypropylene Corp. It is also possible to purchase and use a product having the desired physical properties from these commercially available products.

[0027] (2) Additive (B) The additive (B) used in the present invention will be described in detail below.

[0028] Requirement (B1) The additive (B) used in the present invention has a carboxy group or a structure that becomes a carboxy group precursor in its molecular structure (however, this does not include structures where the structure that becomes a carboxy group precursor produces a lower polyhydric alcohol when the carboxy group is produced). Although the detailed mechanism of action of the additive (B) is unclear, it is believed that because the additive (B) has a carboxy group or a structure that becomes a carboxy group precursor, a compound with a carboxy group is present in the system during combustion, and the carboxy group promotes the reaction with the polypropylene resin (A) and the flame retardant (C) during combustion, further enhancing the effect of the flame retardant (C).

[0029] Additive (B) has a carboxy group or a structure that serves as a precursor of a carboxy group in its molecular structure (excluding structures that serve as precursors of a carboxy group and that generate a lower polyhydric alcohol when a carboxy group is generated). Examples of structures that serve as precursors of a carboxy group include carboxylic acid esters, carboxylic acid amides, carboxylic acid anhydrides, lactones, and lactams. Among these, it is preferable that the precursor of the carboxy group of additive (B) is at least one selected from the group consisting of carboxylic acid esters, carboxylic acid amides, and carboxylic acid anhydrides, because the structure is stable and easy to handle during production and the carboxy group can be easily generated during combustion.

[0030] The additive (B) having a carboxy group in its molecular structure is a compound known as a carboxylic acid. The carboxylic acids are not particularly limited in terms of molecular weight or valence, and examples thereof include monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, behenic acid, and erucic acid, and dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, and terephthalic acid. Other examples of carboxylic acids include hydroxy acids such as glycolic acid, lactic acid, tartronic acid, glyceric acid, hydroxybutyric acid, malic acid, tartaric acid, citramalic acid, citric acid, isocitric acid, leucic acid, mevalonic acid, pantoic acid, ricinoleic acid, quinic acid, shikimic acid, salicylic acid, vanillic acid, and syringic acid, and amino acids such as leucine, isoleucine, methionine, valine, phenylalanine, tryptophan, tyrosine, asparagine, cysteine, glutamine, serine, threonine, aspartic acid, glutamic acid, arginine, histidine, lysine, glycine, and proline. Among these, fatty acids are preferred from the viewpoints of compatibility with resins and ease of handling during production, and higher fatty acids of C12 or higher such as lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, behenic acid, and erucic acid are preferred. The carboxylic acid esters are not particularly limited, and complete or partial esters may be used as appropriate. Examples of the carboxylic acid of the carboxylic acid ester include monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, behenic acid, and erucic acid, and dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, and terephthalic acid. Other examples of carboxylic acids include hydroxy acids such as glycolic acid, lactic acid, tartronic acid, glyceric acid, hydroxybutyric acid, malic acid, tartaric acid, citramalic acid, citric acid, isocitric acid, leucinic acid, mevalonic acid, pantoic acid, ricinoleic acid, quinic acid, shikimic acid, salicylic acid, vanillic acid, and syringic acid, and amino acids such as leucine, isoleucine, methionine, valine, phenylalanine, tryptophan, tyrosine, asparagine, cysteine, glutamine, serine, threonine, aspartic acid, glutamic acid, arginine, histidine, lysine, glycine, and proline. The alcohol condensates of carboxylic acid esters can be any compound other than lower polyhydric alcohols. Among these, fatty acid esters are preferred from the viewpoints of compatibility with resins and ease of handling during production, and complete or partial esters can also be used as appropriate. As the fatty acid of the fatty acid ester, higher fatty acids of C12 or more such as lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, behenic acid, and erucic acid are suitable.

[0031] Furthermore, the carboxylic acid amide is not particularly limited, but is preferably a fatty acid amide, and either a complete or partial amide may be used as appropriate. As the fatty acid of the fatty acid amide, saturated or unsaturated fatty acids with a molecular weight of about 26 to 300, such as oleic acid (unsaturated C18), stearic acid (C18), palmitic acid (C18), myristic acid (C14), lauric acid (C12), erucic acid (unsaturated C22), and behenic acid (C22), can be used, with higher fatty acids of C12 or higher being preferred. The amine condensate of fatty acid amide is not particularly limited.

[0032] Examples of carboxylic acid anhydrides include typical carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride, and acid anhydrides of fatty acids. Fatty acids that are precursors of fatty acid anhydrides include oleic acid (unsaturated C18), stearic acid (C18), palmitic acid (C18), myristic acid (C14), lauric acid (C12), erucic acid (unsaturated C22), behenic acid (C22), etc.

[0033] Furthermore, additive (B) is not intended to be used if the structure serving as a carboxyl group precursor generates a lower polyhydric alcohol upon carboxyl group generation. If the structure serving as a carboxyl group precursor generates a lower polyhydric alcohol upon carboxyl group generation, the lower polyhydric alcohol may be generated upon heating, such as during molding or combustion, and then harmful impurities containing aldehyde groups may be generated through dehydration, oxidation, or the like. For example, it is widely known that the use of glycerol monostearate as an additive produces glycerin, which then generates acrolein, a well-known harmful substance, upon heating. It is not preferable to use such compounds as additive (B), and the present invention allows for the production of a safer flame-retardant material. Examples of lower polyhydric alcohols include polyhydric alcohols having 2 to 6 carbon atoms, such as ethylenediol, glycerin, and propanediol, and sugars having a hydroxy group, such as glucose and fructose.

[0034] (3) Flame retardant (C) The flame retardant (C) used in the present invention will be described in detail below.

[0035] Requirement (C1) The flame retardant (C) used in the present invention is an organic flame retardant. Generally, a larger amount of inorganic flame retardant is required to achieve the required flame retardancy, and the specific gravity increases when a high level of flame retardancy is desired. In contrast, organic flame retardants can achieve flame retardancy at a relatively low addition amount, making it possible to achieve high flame retardancy at a relatively low specific gravity. Therefore, in the present invention, it is necessary to use an organic flame retardant as the flame retardant (C).

[0036] The organic flame retardant used in the present invention is not particularly limited, and various organic flame retardants such as halogen-based, phosphorus-based, and nitrogen compounds such as guanidine-based can be used, but phosphorus-based flame retardants are preferred.

[0037] Any phosphorus-based flame retardant generally used for polyolefins can be used, including compounds modified with various substituents such as trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, trixyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, dimethyl ethyl phosphate, trixyl phosphate, methyl dibutyl phosphate, ethyl dipropyl phosphate, and hydroxyphenyl diphenyl phosphate, phosphate compounds, and compounds or mixtures of phosphazene derivatives containing phosphorus and nitrogen. These phosphorus-based flame retardants may be used alone or in combination of two or more.

[0038] In a preferred embodiment of the present invention, the phosphorus-based flame retardant is a polyphosphate. When a polyphosphate is used as an organic flame retardant, it forms an intumescent layer during a reaction during combustion, making it suitable for flame protection. Examples of polyphosphates include phosphates such as those described in [Patent Document 1] JP-A No. 2003-026935, paragraphs

[0015] to

[0021] .

[0039] In addition to the phosphorus-based flame retardant, other organic flame retardants that do not fall under the category of phosphorus-based flame retardants, such as halogen-based and nitrogen compounds, can also be used.

[0040] Preferred examples of halogen-based flame retardants include organic halogenated aromatic compounds such as halogenated diphenyl compounds, halogenated bisphenol compounds, halogenated bisphenol-bis(alkyl ether) compounds, and halogenated phthalimide compounds, and halogenated bisphenol-bis(alkyl ether) compounds are particularly preferred. Examples of the halogenated diphenyl compound include halogenated diphenyl ether compounds, halogenated diphenyl ketone compounds, and halogenated diphenyl alkane compounds, and among these, halogenated diphenyl alkane compounds such as decabromodiphenylethane are preferred.

[0041] Examples of the halogenated bisphenol compounds include halogenated bisphenylalkanes, halogenated bisphenyl ethers, halogenated bisphenyl thioethers, and halogenated bisphenyl sulfones. Among these, halogenated bisphenyl thioethers such as bis(3,5-dibromo-4-hydroxyphenyl) sulfone are preferred.

[0042] Examples of the halogenated bisphenol bis(alkyl ether) compounds include (3,5-dibromo-4-2,3-dibromopropoxyphenyl)-(3-bromo-4-2,3-dibromopropoxyphenyl)methane, 1-(3,5-dibromo-4-2,3-dibromopropoxyphenyl)-2-(3-bromo-4-2,3-dibromopropoxyphenyl)ethane, 1-(3,5-dibromo-4-2,3-dibromopropoxyphenyl)-3-(3-bromo-4-2,3-dibromopropoxyphenyl)propane, 2,2-bis(3,5- Dibromo-4-2,3-dibromopropoxyphenyl)propane, (3,5-dichloro-4-2,3-dibromopropoxyphenyl)-(3-chloro-4-2,3-dibromopropoxyphenyl)methane, 1-(3,5-dichloro-4-2,3-dibromopropoxyphenyl)-2-(3-chloro-4-2,3-dibromopropoxyphenyl)ethane, 1-(3,5-dichloro-4-2,3-dibromopropoxyphenyl)-3-(3-chloro-4-2,3-dibromopropoxyphenyl)propane, bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl) 1,2-bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl)methane, 1,2-bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl)ethane, 1,3-bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl)propane, bis(3,5-dichloro-4-2,3-dibromopropoxyphenyl)methane, 1,2-bis(3,5-dichloro-4-2,3-dibromopropoxyphenyl)ethane, 1,3-bis(3,5-dichloro-4-2,3-dibromopropoxyphenyl)propane, 2-bis(3,5-dichloro-4-2,3-dibromopropoxyphenyl) nyl)propane, (3,5-dibromo-4-2,3-dibromopropoxyphenyl)-(3-bromo-4-2,3-dibromopropoxyphenyl) ketone, (3,5-dichloro-4-2,3-dibromopropoxyphenyl)-(3-chloro-4-2,3-dibromopropoxyphenyl) ketone, bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl) ketone, bis(3,5-dichloro-4-2,3-dibromopropoxyphenyl) ketone, (3,5-dibromo-4-2,3-dibromopropoxyphenyl)-(3-bromo-4-2,3-dibromopropoxyphenyl) ether, (3,5-dichloro-4-2,3-dibromopropoxyphenyl)-(3-chloro-4-2,3-dibromopropoxyphenyl) ether, bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl) ether, bis(3,5-dichloro-4-2,3-dibromopropoxyphenyl) ether, (3,5-dibromo-4-2,3-dibromopropoxyphenyl) bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl)-(3-bromo-4-2,3-dibromopropoxyphenyl)thioether, (3,5-dichloro-4-2,3-dibromopropoxyphenyl)-(3-chloro-4-2,3-dibromopropoxyphenyl)thioether, bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl)thioether, bis(3,5-dichloro-4-2,3-dibromopropoxyphenyl)thioether ether, (3,5-dibromo-4-2,3-dibromopropoxyphenyl)-(3-bromo-4-2,3-dibromopropoxyphenyl)sulfone, (3,5-dichloro-4-2,3-dibromopropoxyphenyl)-(3-chloro-4-2,3-dibromopropoxyphenyl)sulfone, bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl)sulfone, bis(3,5-dichloro-4-2,3-dibromopropoxyphenyl)sulfone, among which brominated bisphenol A (brominated aliphatic ether), brominated bisphenol S (brominated aliphatic ether), chlorinated bisphenol A (chlorinated aliphatic ether), chlorinated bisphenol S (chlorinated aliphatic ether), especially etherified tetrabromobisphenol A and etherified tetrabromobisphenol S are preferred.

[0043] Examples of etherified tetrabromobisphenol A include tetrabromobisphenol A-bis(2,3-dibromopropyl ether) and 2,2-bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl)propane. Examples of etherified tetrabromobisphenol S include bis(3,5-dibromo-4-2,3-dibromopropoxyphenyl)sulfone. Among these halogen-based flame retardants, bromine-based flame retardants are preferred because they have a high flame retardant effect and are less likely to decompose even when subjected to heat history during the production and molding of the propylene-based resin composition of the present invention.

[0044] Examples of the nitrogen compounds include melamine, piperazine, N,N,N',N'-tetramethyldiaminomethane, ethylenediamine, N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-diethylethylenediamine, 1,2-propanediamine, and 1,3-propanediamine. , tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, trans-2,5-dimethylpiperazine, 1,4-bis(2-aminoethyl)piperazine, 1,4-bis(3-aminopropyl)piperazine, acetoguanamine, benzoguanamine, acrylguanamine, 2,4-diamino-6-nonyl-1,3,5-trimethylguanamine Azine, 2,4-diamino-6-hydroxy-1,3,5-triazine, 2-amino-4,6-dihydroxy-1,3,5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-ethoxy-1,3,5-triazine, 2,4-diamino-6-propoxy-1,3,5-triazine, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6-mercapto-1,3,5-triazine Examples include compounds in which methyltriazine, 2-amino-4,6-dimercapto-1,3,5-triazine, ammeline, benzguanamine, acetoguanamine, phthalodiguanamine, melamine cyanurate, melamine pyrophosphate, butylenediguanamine, norbornenediguanamine, methylenediguanamine, ethylenedimelamine, trimethylenedimelamine, tetramethylenedimelamine, hexamethylenedimelamine, and 1,3-hexylenedimelamine are substituted. Commercially available products include ADEKA Corporation's ADK STAB FP2000, FP2100, FP2200, and FP2500S, as well as ammonium polyphosphate.

[0045] When a phosphorus-based flame retardant is used in combination with various organic flame retardants such as halogen-based and nitrogen-based compounds, the organic flame retardants may be used alone or in combination of two or more. For example, a phosphorus-based flame retardant may be used in combination with an organic halogen-based flame retardant and a nitrogen-based compound.

[0046] (4) Other additives (D) If necessary, the propylene-based resin composition of the present invention may appropriately contain an additive (D), which is an optional component usually used in polypropylene-based resins, within a range that does not impair the object of the present invention. Examples of additives (D) include nucleating agents, molecular weight regulators, foaming agents, pigments, ultraviolet absorbers, antioxidants, antistatic agents, neutralizing agents, metal deactivators, stabilizers, antibacterial agents, inorganic fillers, and rubber-like components.

[0047] As the molecular weight lowering agent, for example, various organic peroxides and those called decomposition (oxidation) accelerators can be used, and organic peroxides are preferred.Specific examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, t-butyl peracetate, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexyne-3, t-butyl-diperadipate, t-butylperoxy-3,5,5-trimethylhexanoate, methyl ethyl ketone peroxide, cyclohexanone peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, Examples of the peroxyhydroxide include, but are not limited to, one or more selected from the group consisting of 1,3-bis-(t-butylperoxyisopropyl)benzene, t-butylcumyl peroxide, 1,1-bis-(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis-(t-butylperoxy)cyclohexane, 2,2-bis-t-butylperoxybutane, p-menthane hydroperoxide, di-isopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, p-cymene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, and 2,5-dimethyl-2,5-di(hydroperoxy)hexane.

[0048] The type of blowing agent that can be used in the present invention is not particularly limited, and known blowing agents used in plastics, rubber, etc. can be used. Also, any blowing agent used in various foam molding processes can be used, including physical blowing agents, decomposable blowing agents (chemical blowing agents), and microcapsules containing a thermal expansion agent. Specific examples of physical blowing agents include aliphatic hydrocarbons such as propane, butane, pentane, and hexane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; halogenated hydrocarbons such as chlorodifluoromethane, difluoromethane, trifluoromethane, trichlorofluoromethane, dichlorodifluoromethane, chloromethane, dichloromethane, chloroethane, dichlorotrifluoroethane, dichlorofluoroethane, chlorodifluoroethane, dichloropentafluoroethane, tetrafluoroethane, difluoroethane, pentafluoroethane, trifluoroethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, chloropentafluoroethane, and perfluorocyclobutane; and inorganic gases such as water, carbon dioxide, and nitrogen. These compounds may be used alone or in combination. Among these, aliphatic hydrocarbons such as propane, butane, and pentane, and carbon dioxide gas are preferred because they are inexpensive and have high solubility in polypropylene-based resins. In particular, when carbon dioxide gas is used, it is more preferred to use it under supercritical conditions of 7.4 MPa or higher and 31°C or higher, because this results in excellent diffusion and solubility in the propylene-based resin composition.

[0049] When a physical foaming agent is used, a foam regulator can be used as needed. Examples of foam regulators include inorganic decomposable foaming agents such as ammonium carbonate, sodium bicarbonate (sodium bicarbonate), ammonium bicarbonate, and ammonium nitrite; azo compounds such as azodicarbonamide, azobisisobutyronitrile, and diazoaminobenzene; nitroso compounds such as N,N'-dinitrosopentanmethylenetetramine and N,N'-dimethyl-N,N'-dinitrosoterephthalamide; organic decomposable foaming agents such as benzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide, p,p'-oxybisbenzenesulfonyl semicarbazide, p-toluenesulfonyl semicarbazide, trihydrazinotriazine, and barium azodicarboxylate; inorganic powders (inorganic powders) such as talc and silica; acid salts of polycarboxylic acids; and reaction mixtures of polycarboxylic acids with sodium carbonate or sodium bicarbonate. These foam regulators can be used alone or in combination. When a cell regulator is used, the blending amount of the cell regulator is preferably in the range of 0.01 to 5 parts by weight in pure form relative to 100 parts by weight of the propylene-based resin composition. Specific examples of decomposable blowing agents (chemical blowing agents) include mixtures of organic acids such as sodium bicarbonate and citric acid, azo-based blowing agents such as azodicarbonamide and barium azodicarboxylate, nitroso-based blowing agents such as N,N'-dinitrosopentamethylenetetramine and N,N'-dimethyl-N,N'-dinitrosoterephthalamide, sulfohydrazide-based blowing agents such as p,p'-oxybisbenzenesulfonylhydrazide and p-toluenesulfonylsemicarbazide, and trihydrazinotriazine. The amount of the foaming agent to be added is preferably in the range of 0.05 to 6.0 parts by weight, more preferably 0.05 to 3.0 parts by weight, even more preferably 0.5 to 2.5 parts by weight, and particularly preferably 1.0 to 2.0 parts by weight, relative to 100 parts by weight of the propylene-based resin composition.

[0050] The pigment may be any of known organic or inorganic pigments, including organic pigments such as azo, anthraquinone, phthalocyanine, quinacridone, isoindolinone, diosadin, perinone, quinophthalone, and perylene pigments, and inorganic pigments such as ultramarine, titanium oxide, titanium yellow, iron oxide (red oxide), chromium oxide, zinc white, and carbon black.

[0051] As the light stabilizer or ultraviolet absorber, for example, hindered amine compounds, benzotriazoles, benzophenones, salicylates, and the like are effective in imparting or improving the weather resistance, durability, etc. of the propylene-based resin composition of the present invention and the molded article obtained by molding it. Specific examples of the hindered amine compound include a condensation product of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine; poly[[6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]]; tetrakis(2,2,6,6-tetramethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate; tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate; bis(1,2,2,6,6-pentamethyi) Examples of the benzotriazole-based stabilizers include 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole and 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole. Examples of the benzophenone-based stabilizers include 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octoxybenzophenone. Examples of the salicylate-based stabilizers include 4-t-butylphenyl salicylate and 2,4-di-t-butylphenyl-3',5'-di-t-butyl-4'-hydroxybenzoate. The combined use of the light stabilizer and UV absorber is preferred due to its significant improvement in weather resistance, durability, and other properties. These stabilizers may be used in combination.

[0052] As the antioxidant, for example, phenol-based, phosphorus-based, and sulfur-based antioxidants are effective in imparting or improving the heat resistance, processing stability, heat aging resistance, etc. of the propylene-based resin composition of the present invention and the molded article obtained by molding it.

[0053] As the antistatic agent, for example, a nonionic or ionic antistatic agent is effective in imparting or improving the antistatic properties of the propylene-based resin composition of the present invention and the molded article obtained by molding it.

[0054] In particular, as the antistatic agent, ionic agents such as cationic, anionic, nonionic and amphoteric agents, and fatty acid partial esters such as glycerin fatty acid monoesters can be used. Specifically, alkyltrimethylammonium salts, dialkyldimethylammonium salts, benzalkonium salts, N,N-bis(2-hydroxyethyl)-N-(3-dodecyloxy-2-hydroxypropyl)methylammonium methosulfate, (3-laurylamidopropyl)trimethylammonium methylsulfate, stearamidopropyldimethyl-2-hydroxyethylammonium nitrate, stearamidopropyldimethyl-2-hydroxyethylammonium phosphate, cationic polymers, alkyl sulfonates, alkylbenzene sulfonates, sodium alkyl diphenyl ether disulfonate, alkyl nitrate ester salts, phosphorus Acid alkyl ester salts, alkyl phosphate amine salts, stearic acid monoglyceride, pentaerythritol fatty acid esters, sorbitan monopalmitate, sorbitan monostearate, diglycerin fatty acid esters, alkyldiethanolamines, alkyldiethanolamine fatty acid monoesters, alkyldiethanolamides, polyoxyethylene dodecyl ethers, polyoxyethylene alkylphenyl ethers, polyethylene glycol monolaurate, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyether block copolymers, cetyl betaine, hydroxyethyl imidazoline sulfate, etc. These may be used in combination of two or more.

[0055] Examples of nucleating agents that can be used include aromatic aluminum salt-based nucleating agents, aromatic sodium salt-based nucleating agents, phosphorus-based nucleating agents such as aromatic metal phosphate-based nucleating agents, sorbitol-based nucleating agents, rosin-based nucleating agents, petroleum resins, and talc. Examples of sorbitols, such as alkyl-substituted benzylidene sorbitol, include 1,3,2,4-dibenzylidene sorbitol, 1,3,2,4-di-(p-methylbenzylidene) sorbitol, 1,3-o-methylbenzylidene 2,4-p-methylbenzylidene sorbitol, 1,3,2,4-di-(p-ethylbenzylidene) sorbitol, and 1,3,2,4-di-(2',4'-dimethylbenzylidene) sorbitol. Phosphorus-based sorbitols include sodium bis(4-t-butylphenyl) phosphate, sodium 2,2'-ethylidene-bis(4,6-di-t-butylphenyl) phosphate, and organic phosphate complexes. Other sorbitols include sodium benzoate, aluminum pt-butylbenzoate, sodium montanate, calcium montanate, aluminum oxide, kaolin clay, talc, rosins, and petroleum resins. These may be used in combination of two or more.

[0056] As the metal deactivator, triazines, phosphones, epoxies, triazoles, hydrazides, oxamides, etc. can be used. Specific examples include N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, isophthalic acid bis(2-phenoxypropionylhydrazide), decanedicarboxylic acid disalicyloyl hydrazide, oxalic acid bisbenzylidenehydrazide, N,N'-bis{2-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxyl]ethyl}oxamide, 3-(N-salicyloyl)amino-1,2,4-triazole, acid amides, melamine, tris[2-t-butyl-4-thio(2'-methyl-4'-hydroxy-5-t-butyl)phenyl-5-methyl]phosphite, etc. These may be used in combination of two or more.

[0057] As the neutralizing agent, various fatty acid metal salts and the like can be used. Specific examples include saturated or unsaturated fatty acids with a molecular weight of about 26 to 300, such as oleic acid (unsaturated C18), stearic acid (C18), palmitic acid (C18), myristic acid (C14), lauric acid (C12), erucic acid (unsaturated C22), and behenic acid (C22), and salts of metals such as lithium, sodium, calcium, magnesium, aluminum, and zinc. Two or more of these may be used in combination.

[0058] The antibacterial agent may be either an organic or inorganic antibacterial agent. Examples of organic antibacterial agents include chlorine-based, phenol-based, imidazole-based, or thiazole-based compounds, and quaternary ammonium compounds. Examples of inorganic antibacterial agents include zeolite-based, apatite-based, silica alumina-based, ceramic-based, zirconium phosphate-based, silica gel-based, hydroxyapatite-based, or calcium silicate-based antibacterial agents containing metals such as silver and zinc.

[0059] Furthermore, specific examples of inorganic fillers include talc, barium sulfate, clay, silica, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, glass fiber, whiskers, and the like.

[0060] The rubber component may be a so-called elastomer or plastomer, such as ethylene-propylene rubber, ethylene-butene-1 rubber, ethylene-hexene rubber, ethylene-octene rubber, or styrene-butadiene rubber. Any commercially available rubber may be used as long as it does not impair the effects of the present invention.

[0061] 2. Method for preparing propylene-based resin composition Examples of methods for preparing the propylene-based resin composition of the present invention include a method in which predetermined amounts of additive (B), flame retardant (C), and optional additive (D) are added directly to powder or pellets of polypropylene-based resin (A); a method in which a masterbatch containing powder of polypropylene-based resin (A), additive (B), flame retardant (C), and optional additive (D) is prepared in advance and added to pellets of polypropylene-based resin; a method in which additive (B) and optional additive (D) are added to powder or pellets of polypropylene-based resin (A) to first prepare a masterbatch of additive (B), and then flame retardant (C) and optional additive (D) are added to powder or pellets of polypropylene-based resin (A) to prepare a masterbatch of flame retardant (C), and then the obtained masterbatch of additive (B) and masterbatch of flame retardant (C) are melt-kneaded together.

[0062] The propylene-based resin composition of the present invention can be obtained by any of the above methods. When these methods are used, known methods such as a tumbler mixer, a super mixer, a Henschel mixer, a screw blender, a ribbon blender, etc. Melt kneading is not particularly limited as long as it is a method in which melt kneading is carried out at a temperature equal to or higher than the melting point of the polypropylene resin (A) using, for example, a melt extruder, a Banbury mixer, etc.

[0063] The propylene-based resin composition of the present invention has an overall melt flow rate (MFR, 230°C, 2.16 kg load) of usually 1 to 60 g / 10 min, preferably 2 to 50 g / 10 min, more preferably 5 to 40 g / 10 min, and particularly preferably 10 to 30 g / 10 min. By setting the overall MFR within this range, good moldability can be maintained while at the same time good flame retardancy can be obtained.

[0064] 3. Molding and applications of propylene-based resin compositions (1) Molding Another aspect of the present invention is a molded article obtained from the propylene-based resin composition of the present invention. The propylene-based resin composition of the present invention can be molded by injection molding (including gas injection molding) or injection compression molding (including press injection, hot flow stamping molding, and gas injection compression molding). Among these, the effects of the present invention can be more effectively obtained by injection molding other than gas injection molding or injection compression molding (press injection), and it is preferable to obtain a molded article by such a molding method. The propylene-based resin composition of the present invention can be molded, as needed, by various molding methods such as blow molding, extrusion molding, compression (press) molding, foam (expansion) molding, sheet molding, thermoforming, stamping molding, and powder molding, thereby obtaining a desired molded product (e.g., an extrusion molded product). Among these, molding methods other than foam (expansion) molding are preferred.

[0065] (2)Applications Applications of the injection-molded articles obtained from the propylene-based resin composition of the present invention include, for example, parts for home appliances such as rice cookers, vacuum cleaners, washing machines, refrigerators, electric fans, and air conditioners; parts for housing facilities such as vanities, ventilation fans, toilet seats, toilet covers, and housings for devices used as accessories; general batteries and battery peripheral parts; and battery peripheral parts for electric vehicles. [Example]

[0066] The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The evaluation methods and materials used in the examples are as follows.

[0067] 1. Evaluation Method 1) Flame retardant UL94-V Flame retardancy evaluation test pieces (thickness: 3.0 mm) were molded in accordance with the UL94-V standard using an injection molding machine [Toshiba IS100] and evaluated. If the evaluation did not meet the UL94-V standard, it was marked as "failed." The evaluation was as follows: ◎:V0 〇:V1 △:V2 ×: Fail 2) Specific gravity Measurements were made in accordance with JIS K7112. The results are as follows: 〇:0.99g / cm 3 below △: 0.99 g / cm 3 Exceeds 1.00 g / cm 3 below ×:1.00g / cm 3 exceed 3) Overall evaluation Based on the above flame retardancy and specific gravity evaluations, a comprehensive evaluation was made as follows. ○: In both cases, there are no × or △, and only ○ and ◎ are judged. △: There are no ×s in both judgments, but there are one or more △s ×: If there is one or more × in both judgments

[0068] 2.Material Polypropylene resin (A) (A-1) Novatec PP series, MA1B (MFR: 20g / 10min), manufactured by Japan Polypropylene Corporation Additive (B) (B-1) Kao's Lunac S-50V (stearic acid), (B-2) Riken Vitamin's Rikemal SL-800 (stearyl stearate) Organic flame retardants (C) (C-1) ADEKA FP2500S (a phosphorus-based flame retardant containing polyphosphate) Other additives (D) Other additives (D) used included antioxidants (D-1: BASF, Irganox 1010) and (D-2: ADEKA, Irgafos 168).

[0069] 2. Preparation of test specimens 1) Examples 1 to 4 and Comparative Examples 1 to 2 Polypropylene resin (A), additive (B), phosphorus-based flame retardant (C), and other additives (D) were blended in the proportions shown in Table 1 and mixed at room temperature for 3 minutes using a high-speed agitator mixer (Henschel Mixer, product name). The mixture was then melt-kneaded and extruded using a twin-screw extruder, passed through a cold water bath, and the strands were cut using a strand cutter to obtain pellets. The resulting pellets were molded using an injection molding machine to obtain test pieces conforming to the UL94-V standard, which were then evaluated according to the evaluation methods described above. The evaluation results are shown in Table 1.

[0070] [Table 1]

[0071] 3. Evaluation Results The results shown in Table 1 show that the use of additives (B) makes it possible to provide excellent flame retardancy while maintaining a low specific gravity. That is, in Examples 1 to 4, the specific gravity of the base polypropylene resin (A) was approximately 0.90 g / cm 3 Therefore, it is possible to exhibit sufficient flame retardancy while keeping the upper limit of specific gravity within 10%. On the other hand, looking at Comparative Example 1, which does not contain additive (B), the specific gravity is at the same level as in Examples 1 to 4, but flame retardancy is not exhibited. Furthermore, while it is possible to improve flame retardancy by increasing the amount of flame retardant (C) as in Comparative Example 2, the specific gravity becomes higher than in Examples 1 to 4, and it is not possible to provide a material that achieves both flame retardancy and a low specific gravity.

[0072] From these examples and comparative examples, it is clear that the additive (B) is essential to achieve both the flame retardancy and low specific gravity required in the present invention. [Industrial Applicability]

[0073] The propylene-based resin composition of the present invention can provide a material that has both low specific gravity and excellent flame retardancy, and can be suitably used for automobile parts, electrical parts, container and packaging materials, building materials, large members, etc.

Claims

1. A propylene-based resin composition comprising a polypropylene-based resin (A) that satisfies the following requirement (A1), an additive (B) that satisfies the following requirement (B1), and a flame retardant (C) that satisfies the following requirement (C1), and characterized by satisfying the following condition 1: Requirement (A1) The polypropylene resin (A) contains at least one propylene polymer selected from the group consisting of propylene homopolymers, propylene random copolymers, and propylene block copolymers. Requirement (B1) The additive (B) has a carboxy group or a structure that serves as a precursor of a carboxy group in its molecular structure (however, this does not include structures in which the structure that serves as a precursor of a carboxy group generates a lower polyhydric alcohol when a carboxy group is generated). Requirement (C1) The flame retardant (C) is an organic flame retardant. Condition 1 The propylene-based resin composition contains 78.5 to 86.7 wt % of a polypropylene-based resin (A), 0.3 to 1.5 wt % of an additive (B), and 13 to 20 wt % of a flame retardant (C) (wherein the total of the polypropylene-based resin (A), the additive (B), and the flame retardant (C) is 100 wt %).

2. 2. The propylene-based resin composition according to claim 1, wherein the precursor of the carboxy group of the additive (B) is at least one selected from the group consisting of carboxylic acid esters, carboxylic acid amides, and carboxylic acid anhydrides.

3. 2. The propylene-based resin composition according to claim 1, wherein the flame retardant (C) is a phosphorus-based flame retardant.

4. 3. The propylene-based resin composition according to claim 2, wherein the flame retardant (C) is a phosphorus-based flame retardant.

5. A molded article obtained from the propylene-based resin composition according to any one of claims 1 to 4.

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