JP6948003B2 - Flame-retardant polyolefin resin composition - Google Patents

Description

The present invention relates to a flame-retardant polyolefin resin composition. More specifically, the present invention relates to a flame-retardant polyolefin resin composition having excellent heat resistance, flexibility, flame retardancy, productivity, and oil resistance. The flame-retardant polyolefin resin composition of the present invention is excellent in heat resistance, flexibility, flame retardancy, productivity and oil resistance, and is suitable as an electric wire coating material.

Since the polyvinyl chloride resin composition has excellent electrical insulation and self-extinguishing flame-retardant properties, it has been widely used for electric wire coatings, tubes, tapes, building materials, automobile parts, home appliance parts, etc. There is. However, since the polyvinyl chloride resin composition contains chlorine, hydrogen chloride gas, which is a corrosive gas, may be generated during combustion, and toxic gas such as dioxins may be generated depending on the combustion conditions. For this reason, as part of measures to deal with recent environmental problems, halogen-free materials that have little possibility of generating these toxic gases during combustion (hereinafter, halogen-free materials may be referred to as "non-halogen". .) Is now used.

Examples of the non-halogen-based material include polyolefin-based resins and styrene-based resins typified by polypropylene and polyethylene. However, since polyolefin-based resins and the like are not flame-retardant, it is necessary to make them flame-retardant depending on the application. As a countermeasure, a method of adding a halogen-based flame retardant has been used for a long time. However, since halogen-based flame retardants may also generate toxic gas during combustion, a method of blending metal hydroxides such as magnesium hydroxide and aluminum hydroxide as non-halogen flame retardants has recently been adopted. There is.

However, the flame retardant resin composition containing magnesium hydroxide, aluminum hydroxide and the like can prevent the generation of halogen-based gas during combustion, but requires flame retardant performance, for example, UL-94 test V-0. In order to obtain the level, it is necessary to fill a large amount of flame retardant, which causes problems such as inferior physical properties of the resin composition and inferior molding processing characteristics.

Many have been proposed in which a small amount of a halogen-based flame retardant is used in order to impart physical characteristics, molding processing characteristics, and flame retardant performance to the resin composition (for example, Patent Documents 1 to 8).

Japanese Unexamined Patent Publication No. 2001-220470 Japanese Unexamined Patent Publication No. 2001-226539 Japanese Unexamined Patent Publication No. 2000-248132 Japanese Unexamined Patent Publication No. 5-303918 Japanese Unexamined Patent Publication No. 2011-243446 JP-A-2009-43601 Japanese Unexamined Patent Publication No. 2001-279552 Japanese Unexamined Patent Publication No. 60-170612

There is a strong demand for the application of flame-retardant polyolefin materials in high-temperature environments such as engine rooms, and there is a strong demand for improved heat resistance in electric wire coating applications for automobile parts.
According to the findings of the present inventors, for example, the resin compositions of Patent Documents 2 and 7 have insufficient heat resistance at a high temperature of 150 ° C. or higher. At present, no flame-retardant resin composition having excellent properties, flexibility, productivity, and oil resistance has been provided.

The present invention has been made in view of the above circumstances, and an object of the present invention is excellent in heat resistance, flexibility, and flame retardancy, and also in oil resistance, particularly flame retardancy having excellent oil resistance and productivity at high temperatures. An object of the present invention is to provide a sex polyolefin resin composition. Another object of the present invention is to provide a flame-retardant polyolefin resin composition which is excellent in heat resistance, flexibility, flame retardancy, productivity and oil resistance and is suitable as a wire coating material.

As a result of diligent studies in view of the above problems, the present inventor has moved an olefin polymer containing a specific propylene-ethylene block copolymer, a thermoplastic resin, a softener for paraffin rubber, a cross-linking agent, and a flame retardant. It has been found that the polyolefin-based resin composition obtained by cross-linking is excellent in heat resistance, flexibility and flame retardancy, and also excellent in oil resistance and productivity at high temperature. The present invention has been achieved based on these findings, and the gist of the present invention is as follows.

[1] A flame-retardant polyolefin resin composition obtained by dynamically cross-linking a mixture containing the following components (A) to (E).
Component (A): Olefin-based polymer component (B) containing a propylene-ethylene block copolymer having a melting end temperature of 166 to 175 ° C .: Thermoplastic resin component (C) containing an ethylene-α-olefin copolymer: Softener component for paraffin rubber (D): Cross-linking agent component (E): Flame retardant

[2] The flame retardancy according to [1], wherein the MFR (230 ° C., 21.2 N load) of the propylene-ethylene block copolymer in the component (A) is 0.05 to 2.0 g / 10 minutes. Polyolefin-based resin composition.

[3] The flame-retardant polyolefin resin composition according to [1] or [2], wherein the component (A) contains a propylene random copolymer.

[4] The flame-retardant polyolefin-based according to any one of [1] to [3], wherein the ethylene content of the propylene-ethylene block copolymer in the component (A) in the rubber is 72 to 90% by mass. Resin composition.

[5] The flame retardant according to any one of [1] to [4], wherein the component (B) contains an ethylene-α-olefin-non-conjugated diene copolymer having an ethylene unit content of 50 to 75% by mass. Polyolefin-based resin composition.

[6] The flame-retardant polyolefin resin composition according to [5], wherein the component (B) contains the following component (B3).
Component (B3): A block copolymer having at least two polymer blocks P derived from a vinyl aromatic compound and at least one polymer block Q derived from conjugated diene and / or isobutylene, and the blocks. At least one block copolymer in the group consisting of block copolymers obtained by hydrogenating a copolymer.

[7] The flame-retardant polyolefin according to any one of [1] to [6], wherein the ratio of the component (B) to a total of 100 parts by mass of the component (A) and the component (B) is 40 to 80 parts by mass. Based resin composition.

[8] The flame-retardant polyolefin resin composition according to any one of [1] to [7], wherein the component (D) contains an organic peroxide and a cross-linking aid.

[9] The component (E) is a brominated flame retardant and / or an antimony flame retardant, and the ratio of the component (E) to a total of 100 parts by mass of the component (A) and the component (B) is 30 to 80 parts by mass. The flame-retardant polyolefin resin composition according to any one of [1] to [3].

[10] A molded product obtained by molding the flame-retardant polyolefin resin composition according to any one of [1] to [9].

[11] The molded product according to [10], which is an electric wire covering material.

According to the present invention, a flame-retardant polyolefin resin composition having excellent heat resistance, flexibility, and flame retardancy, and also having excellent oil resistance and productivity at high temperatures, and an electric wire coating material using the resin composition. Is provided.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and carried out without departing from the gist of the present invention. In addition, in this specification, when a numerical value or a physical property value is put before and after using "~", it is used as including the value before and after that.

[Flame-retardant polyolefin resin composition]
The flame-retardant polyolefin resin composition of the present invention is formed by dynamically cross-linking a mixture containing the following components (A) to (E) (hereinafter, may be referred to as "mixture of the present invention").
Component (A): Olefin-based polymer component (B) containing a propylene-ethylene block copolymer having a melting end temperature of 166 to 175 ° C .: Thermoplastic resin component (C) containing an ethylene-α-olefin copolymer: Softener component for paraffin rubber (D): Cross-linking agent component (E): Flame retardant

The flame-retardant polyolefin-based resin composition of the present invention has the effects of being excellent in heat resistance, flexibility, and flame retardancy, as well as being excellent in oil resistance and productivity at high temperatures. It is presumed that the flame-retardant polyolefin resin composition of the present invention has good heat resistance when it uses an olefin polymer containing a specific propylene-ethylene block copolymer as a raw material. Further, when a specific thermoplastic resin is used, as a result, the proportion of aromatics contained in the polyolefin resin composition increases, so that the oil resistance performance to hydrocarbon-based oils incompatible with aromatics is improved.

[Ingredient (A)]
The component (A) is an olefin polymer containing a propylene-ethylene block copolymer having a melting end temperature of 166 to 175 ° C.

The melting end temperature of the propylene-ethylene block copolymer contained in the component (A) and the propylene random copolymer described later can be measured by the following method according to JIS K7121. That is, the following steps (1) to (3) are sequentially carried out using a differential scanning calorimeter (DSC6220 manufactured by SSI Nanotechnology) to melt the propylene random copolymer and the propylene-ethylene block copolymer. To measure. In each process, time is plotted on the horizontal axis and heat of fusion is plotted on the vertical axis to obtain a melting curve, and the outer peak end point (° C) of the peak observed in step (3) is calculated and used as the melting point end temperature. ..
Step (1): The temperature of 5 mg of the sample is raised from room temperature to 100 ° C./min at a rate of 40 ° C. to 200 ° C., and the temperature is maintained for 3 minutes after the temperature rise is completed.
Step (2): The temperature is lowered from 200 ° C. to 40 ° C. at a rate of 10 ° C./min, and the temperature is maintained for 3 minutes after the temperature reduction is completed.
Step (3): The temperature is raised from 40 ° C. to 200 ° C. at a rate of 10 ° C./min.

Heat resistance is imparted when the melting end temperature of the propylene-ethylene block copolymer contained in the component (A) is 166 ° C. From this point of view, the melting end temperature of this propylene-ethylene block copolymer is 166 ° C. or higher, preferably 170 ° C. or higher, while the upper limit is not particularly limited, but is usually 175 ° C. or lower.

In the propylene-ethylene block copolymer contained in the component (A), the ethylene content in the rubber is measured by the method described in Examples described later, and is preferably 72 to 90% by mass, more preferably. It is 75 to 85% by mass, more preferably 80 to 85% by mass. When the ethylene content in the rubber is in the above range, the soluble content at 140 ° C. tends to increase, which is preferable because the heat resistance is excellent.

The propylene-ethylene block copolymer contained in the component (A) also has a 140 ° C. soluble content (this value is an index of heat resistance) measured by the method described later, which is 50% by mass or more. Is preferable. Here, if the propylene-ethylene block copolymer having a 140 ° C. soluble content of 50% by mass or more is used, there are few soluble portions at high temperatures, and the heat resistance is excellent. From this viewpoint, the 140 ° C. soluble content of the propylene-ethylene block copolymer is more preferably 55% by mass or more, further preferably 60% by mass or more. On the other hand, the upper limit of the 140 ° C. soluble content is usually 95% by mass or less from the viewpoint of moldability.

The propylene-ethylene block copolymer contained in the component (A) preferably satisfies at least one of the above-mentioned suitable ethylene content in rubber and the content soluble at 140 ° C., and more preferably both.

The melt flow rate (MFR) of the propylene-ethylene block copolymer contained in the component (A) is preferably 0.05 to 2.6 g / 10 minutes. When the MFR of the propylene-ethylene block copolymer is 0.05 g / 10 minutes or more, the moldability is good, and when it is 2.6 g / 10 minutes or less, the dispersibility during melt kneading is good. It becomes. From these viewpoints, the MFR of the propylene-ethylene block copolymer is more preferably 0.10 g / 10 minutes or more, still more preferably 0.50 g / 10 minutes or more, while more preferably 2.6 g. It is / 10 minutes or less, and more preferably 2.0 g / 10 minutes or less.

The melt flow rate (230 ° C., 21.2N) of the propylene-ethylene block copolymer contained in the component (A) and the propylene random copolymer described later is measured at a measurement temperature of 230 ° C. according to JIS K7210 (1999). , Measured under the condition of measuring load 21.2N.

The olefin polymer of the component (A) preferably further contains a propylene random copolymer in addition to the above-mentioned propylene-ethylene block copolymer.

A propylene random copolymer is a copolymer having a propylene unit and a constituent unit other than propylene. Specific examples of the constituent units other than propylene include ethylene units and α-olefin units other than propylene units. Examples of the constituent units other than the propylene unit that the propylene random copolymer may contain include ethylene unit, 1-butene unit, 1-pentene unit, 1-hexene unit, 1-hepten unit, and 1-octene unit. , 1-Nonene unit, 1-decene unit, 1-ethylene unit, 1-dodecene unit, 1-tridecene unit, 1-tetradecene unit, 1-pentadecene unit, 1-hexadecene unit, 1-heptadecene unit, 1-octadecene unit , 1-nonadecene unit, 1-eicosene unit, 3-methyl-1-butene unit, 3-methyl-1-pentene unit, 4-methyl-1-pentene unit, 2-ethyl-1-hexene unit, 2,2 , 4-trimethyl-1-pentene unit and the like, preferably ethylene unit and 1-butene unit. The propylene random copolymer may contain only one of these, or may contain two or more of them.

In the above propylene random copolymer, the content of the propylene unit is preferably 90 to 99% by mass, more preferably 93 to 98% by mass. When the content of the propylene unit of the propylene random copolymer is in the above range, it is preferable from the viewpoint of moldability.

The melt flow rate (MFR) of the above propylene random copolymer is preferably 0.05 to 100 g / 10 minutes. When the MFR of the propylene random copolymer is 0.05 g / 10 minutes or more, the dispersibility during melt-kneading is improved, and when it is 100 g / 10 minutes or less, the mechanical properties are improved. From these viewpoints, the MFR of the propylene random copolymer is more preferably 0.05 g / 10 minutes or more, further preferably 0.5 g / 10 minutes or more, and more preferably 100 g / 10 minutes or less. It is more preferably 50 g / 10 minutes or less.

The melting end temperature of the propylene random copolymer is preferably 105 ° C. or higher, more preferably 115 ° C. or higher, and even more preferably 125 ° C. or higher. On the other hand, the melting end temperature of the propylene random copolymer is preferably 150 ° C. or lower, more preferably 140 ° C. or lower. When the melting end temperature of the propylene random copolymer is at least the above lower limit value, it is preferable from the viewpoint of heat resistance, and when it is at least the above upper limit value, unmelted lumps are less likely to appear, which is preferable from the viewpoint of moldability.

As a method for producing the propylene-ethylene block copolymer and the propylene random copolymer contained in the component (A), a known polymerization method using a known olefin polymerization catalyst is used. For example, a polymerization method using a Ziegler-Natta catalyst can be mentioned. As the polymerization method, a slurry polymerization method, a solution polymerization method, a massive polymerization method, a gas phase polymerization method and the like can be used, and two or more of these may be combined.

The above-mentioned propylene-ethylene block copolymer and propylene random copolymer can also be obtained as commercial products. Commercial products that fall under these categories include Prime Polymer Co., Ltd.'s Prim Polypro (registered trademark), Sumitomo Chemical Co., Ltd.'s Sumitomo Noblen (registered trademark), SunAllomer Ltd.'s polypropylene block copolymer, Japan Polypropylene Corporation's Novatec (registered trademark) PP, and Lyondell Basell. Moplen (registered trademark), ExxonMobile (ExxonMobile PP), Polymera Plastics (registered trademark), Borealis PP, LG Chemical's SEETEC PP, A.M. Schulman's ASI POLYPROPYLENE, INEOS Olefins & Polymers, Inc. of INEOS PP, Braskem's Braskem PP, SAMSUNG TOTAL PETROCHEMICALS's Sumsung Total, Sabic's Sabic (registered trademark) PP, TOTAL PETROCHEMICALS company of TOTAL PETROCHEMICALS Polypropylene, SK Corporation of YUPLENE ( There are registered trademarks), etc., and they can be appropriately selected from these and used in combination.

In the present invention, the content of the propylene-ethylene block copolymer in the component (A) is preferably 40% by mass or more, more preferably 50% by mass or more, and more preferably 60% by mass or more. More preferred. On the other hand, the content of the propylene-ethylene block copolymer is preferably 90% by mass or less, preferably 80% by mass or less, and preferably 70% by mass or less. When the content of the propylene-ethylene block copolymer in the component (A) is at least the above lower limit, the heat resistance is excellent, and when it is at least the above upper limit, unmelted lumps are less likely to appear, which is preferable from the viewpoint of moldability.

In the present invention, when the component (A) contains a propylene random copolymer, the content thereof is preferably 10% by mass or more, more preferably 15% by mass or more, and 20% by mass or more. Is even more preferable. On the other hand, the content of the propylene random copolymer is preferably 60% by mass or less, preferably 50% by mass or less, and preferably 40% by mass or less. When the content of the propylene random copolymer in the component (A) is not less than the above lower limit, it is good from the viewpoint of moldability, and it is excellent in heat resistance which is not more than the above upper limit.

Further, in this case, the mass ratio of the propylene-ethylene block copolymer and the propylene random copolymer in the component (A) ([mass of the propylene-ethylene block copolymer]: [mass of the propylene random copolymer]. ]) Is preferably 90:10 to 40:60 from the viewpoint of achieving both moldability and heat resistance, and more preferably 80:20 to 50:50 from this viewpoint.

It should be noted that only one type of each of the propylene-ethylene block copolymer and the propylene random copolymer may be used, or two or more types having different compositions and physical properties may be used in combination.

Further, the component (A) may contain an olefin polymer other than the propylene-ethylene block copolymer and the propylene random copolymer as long as the effect of the present invention is not impaired, and the component (A) may be contained. Examples of other olefin-based polymers include one or more propylene homopolymers.

[Component (B)]
The component (B) used in the flame-retardant polyolefin resin composition of the present invention is a thermoplastic resin containing an ethylene-α-olefin copolymer (excluding those corresponding to the component (A)). The component (B) may further contain the following component (B3).
Component (B3): A block copolymer having at least two polymer blocks P derived from a vinyl aromatic compound and at least one polymer block Q derived from conjugated diene and / or isobutylene, and the blocks. At least one block copolymer component (B) in the group consisting of block copolymers obtained by hydrogenating a copolymer is a component that imparts flexibility to the flame-retardant polyolefin resin composition of the present invention. be.

The ethylene-α-olefin copolymer contained in the component (B) is not particularly limited as long as it is a copolymer containing at least an ethylene unit and an α-olefin unit, but specifically, the following component (B1) and the component (B2) can be mentioned. Either the component (B1) or the component (B2) may be used alone or in combination, but it is preferable that the component (B) contains at least the component (B1).
Component (B1): Ethylene-α-olefin-non-conjugated diene copolymer Component (B2): Ethylene-α-olefin copolymer

The α-olefin unit contained in the component (B1) includes 1-propylene unit, 1-butene unit, 2-methylpropylene unit, 1-pentene unit, 3-methyl-1-butene unit, 1-hexene unit, and 4 Examples thereof include −methyl-1-pentene unit and 1-octene unit. The α-olefin unit used in the component (B1) is preferably the number of carbon atoms having an intercarbon double bond at the terminal carbon atom such as 1-propylene unit, 1-butene unit, 1-hexene unit, 1-octene unit and the like. It is an α-olefin unit of 3 to 8. As for the α-olefin in the component (B1), only one kind may be copolymerized with ethylene, or two or more kinds may be copolymerized with ethylene.

The monomer unit (non-conjugated diene unit) based on the non-conjugated diene contained in the component (B1) includes 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, and 6-methyl. Chain non-conjugated diene such as -1,5-heptadiene, 7-methyl-1,6-octadien; cyclohexadiene, dicyclopentadiene, methyltetrahydroinden, 5-vinylnorbornene, 5-ethylidene-2-norbornene, Cyclic non-conjugated diene such as 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene and the like can be mentioned. Of these, 5-ethylidene-2-norbornene and dicyclopentadiene are preferable.

The content of the ethylene unit of the component (B1) is preferably 50% by mass or more, more preferably 55% by mass or more, still more preferably, with respect to the total amount of the monomer units constituting the component (B1). Is 60% by mass or more, preferably 75% by mass or less, and more preferably 70% by mass or less. It is preferable that the content of ethylene units is in the above range because it gives appropriate flexibility.

In the component (B1), the content of the α-olefin unit is preferably 20% by mass or more, more preferably 25% by mass or more, based on the total amount of the monomer units constituting the component (B1). On the other hand, it is preferably 40% by mass or less, and more preferably 35% by mass or less. It is preferable that the content of the α-olefin unit is in the above range in order to give appropriate flexibility.

In the component (B1), the content of the non-conjugated diene unit is preferably 1% by mass or more, preferably 2% by mass or more, based on the total amount of the monomer units constituting the component (B1). On the other hand, it is preferably 10% by mass or less, and preferably 7% by mass or less. When the content of the non-conjugated diene unit is at least the above lower limit value, it is preferable from the viewpoint of increasing the degree of cross-linking of the flame-retardant polyolefin resin composition, and when it is at least the above upper limit value, it is preferable from the viewpoint of moldability.

The content of each structural unit of the component (B1) can be determined by infrared spectroscopy.

The Mooney viscosity (ML _{1 + 4} , 125 ° C.) of the component (B1) is usually 30 to 120, preferably 40 to 100. The Mooney viscosity (ML _{1 + 4} , 125 ° C.) of the component (B1) is preferably in the above range from the viewpoint of moldability.

The density of the component (B1) is ^{preferably 0.850 g / cm 3} or more, more preferably 0.860 g / cm ³ or more, and preferably 0.900 g / cm ³ or less. , 0.890 g / cm ³ or less, more preferably. When the density of the component (B1) is at least the above lower limit value, it is preferable from the viewpoint of workability, while when it is at least the above upper limit value, it is preferable from the viewpoint of flexibility.

As a method for producing the component (B1), a known polymerization method using a known catalyst for olefin polymerization is used. For example, a slurry polymerization method, a solution polymerization method, a massive polymerization method, a gas phase polymerization method and the like using a Ziegler-Natta catalyst, a complex catalyst such as a metallocene complex or a non-metallocene complex can be mentioned.

A commercially available product can also be used as the component (B1). For example, JSR EPR, EP57C manufactured by JSR, Mitsui EPT manufactured by Mitsui Chemicals, Esplen (registered trademark) manufactured by Sumitomo Chemical, Keltan (registered trademark) manufactured by LANXESS, Nordel (registered trademark) manufactured by Dow, and Vistalon (registered trademark) manufactured by Dow. Applicable products can be selected and used from (registered trademarks), etc.

The α-olefin unit that can be contained in the component (B2) includes 1-propylene unit, 1-butene unit, 2-methylpropylene unit, 1-pentene unit, 3-methyl-1-butene unit, and 1-hexene. Units, 4-methyl-1-pentene units, 1-octene units and the like can be exemplified. The α-olefin unit used in the component (B2) is preferably the number of carbon atoms having an intercarbon double bond at the terminal carbon atom such as 1-propylene unit, 1-butene unit, 1-hexene unit, 1-octene unit and the like. It is an α-olefin unit of 3 to 8. As for the α-olefin in the component (B2), only one kind may be copolymerized with ethylene, or two or more kinds may be copolymerized with ethylene.

The content of the ethylene unit of the component (B2) is preferably 50% by mass or more, preferably 55% by mass or more, based on the total amount of the ethylene unit content and the α-olefin unit content. It is more preferably 60% by mass or more, and on the other hand, it is preferably 80% by mass or less, and more preferably 75% by mass or less. In the above range, the content of the ethylene unit of the component (B2) is preferably large in order to prevent fusion due to blocking of the component (B2), and when the flame-retardant polyolefin resin composition of the present invention is molded. From the viewpoint of low temperature impact resistance, it is preferable that the amount is small. The content of each structural unit in the component (B2) can be determined by infrared spectroscopy.

Specifically, as the component (B2), ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, ethylene-propylene-1- Examples thereof include a butene copolymer, an ethylene-propylene-1-hexene copolymer, and an ethylene-propylene-1-octene copolymer. Among these, ethylene-1-butene copolymer and ethylene-1-octene copolymer are preferable.

The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the component (B2) is usually 20 to 120, preferably 30 to 100. The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the component (B2) is preferably in the above range from the viewpoint of moldability.

The density of the component (B2) is ^{preferably 0.850 g / cm 3} or more, more preferably 0.860 g / cm ³ or more, and preferably 0.900 g / cm ³ or less. , 0.890 g / cm ³ or less, more preferably. When the density of the component (B2) is at least the above lower limit value, it is preferable from the viewpoint of workability, while when it is at least the above upper limit value, it is preferable from the viewpoint of flexibility.

As a method for producing the component (B2), a known polymerization method using a known catalyst for olefin polymerization is used. For example, as a catalyst for olefin polymerization, a Ziegler-Natta catalyst, a complex catalyst such as a metallocene complex or a non-metallocene complex can be used, and as a polymerization method, a slurry polymerization method, a solution polymerization method, a massive polymerization method, or a ki Examples include a phase polymerization method. Further, as the component (B2), a commercially available product can be used, and examples of the commercially available product include the Engage (registered trademark) series manufactured by Dow Chemicals and the Toughmer (registered trademark) series manufactured by Mitsui Chemicals.

In the component (B), when the component (B1) and the component (B2) are used in combination as an ethylene-α-olefin copolymer, the weight ratio of these ([weight of the component (B1)]: [component (B2) Weight]) is preferably 1: 9 to 9: 1 from the viewpoint of reducing lumps during extrusion molding, and more preferably 3: 7 to 7: 3 from this viewpoint.
However, in the present invention, it is preferable to use the component (B1) as the ethylene-α-olefin copolymer from the viewpoint of moldability.
As the component (B1) and the component (B2), only one type may be used, or two or more types having different compositions and physical properties may be used in combination.

The component (B3) used in the present invention has a block co-weight having at least two polymer blocks P derived from a vinyl aromatic compound and at least one polymer block Q derived from conjugated diene and / or isobutylene. It is at least one block copolymer in the group consisting of a block copolymer and a block copolymer obtained by hydrogenating the block copolymer. The flame-retardant polyolefin resin composition of the present invention can have the effect of improving oil resistance and moldability at high temperatures by blending the component (B3).

In the component (B3), the monomeric vinyl aromatic compound constituting the block P is not particularly limited, but a styrene derivative such as styrene or α-methylstyrene is preferable. Above all, it is preferable to mainly use styrene. Here, "mainly" in the component (B3) means that it is 50% by mass or more. The block P may contain a monomer other than the vinyl aromatic compound as a raw material.

Examples of the monomer other than the vinyl aromatic compound include ethylene and α-olefin. When the block P contains a monomer other than the vinyl aromatic compound as a raw material, the content thereof is less than 50% by mass, preferably 40% by mass or less. When the content of the monomer other than the vinyl aromatic compound is in this range, the effect of improving oil resistance and moldability at high temperature can be obtained.

The conjugated diene of the monomer constituting the block Q is not particularly limited, but it is preferably mainly composed of butadiene and / or isoprene, and more preferably butadiene and isoprene. The block Q may contain a monomer other than the conjugated diene as a raw material.

Examples of the monomer other than the conjugated diene include isobutylene and styrene. When the block Q contains a monomer other than the conjugated diene as a raw material, the content thereof is less than 50% by mass, preferably 40% by mass or less. When the content of the monomer other than the conjugated diene is in this range, bleed-out tends to be suppressed.

The block copolymer of the component (B3) is a hydrogenated block copolymer obtained by hydrogenating a block copolymer having at least two of the above-mentioned polymer blocks P and at least one of the above-mentioned polymer blocks Q. May be. More specifically, it may be a hydrogenated block copolymer in which the double bond of the block Q of the block copolymer is hydrogenated. The hydrogenation rate of the block Q is not particularly limited, but is preferably 80 to 100% by mass, more preferably 90 to 100% by mass. By hydrogenating the block Q in the above range, the adhesive property of the obtained modified polyolefin composition tends to decrease and the elastic property tends to increase. The same applies to the case where the block P uses a diene component as a raw material. The hydrogenation rate can be measured by ^{13 C-NMR.}

When the conjugated diene of the monomer constituting the block Q is butadiene, the butadiene in the microstructure can have a 1,4-addition structure and a 1,2-addition structure. In particular, the block Q is hydrogenated. When it is a derivative and is mainly composed of butadiene, the 1,4-addition structure of butadiene in the microstructure of block Q is preferably 10 to 100% by mass.

When the conjugated diene of the monomer constituting the block Q is isoprene, the isoprene in the microstructure can have a 1,2-addition structure, a 1,4-addition structure and a 3,4-addition structure. Similarly, particularly when the block Q is a hydrogenated derivative and the block Q is composed of isoprene, the 1,4-addition structure of isoprene in the microstructure of the block Q is 60 to 100% by mass. Is preferable.

When the block Q is a hydrogenated derivative and the conjugated diene of the monomer constituting the block Q contains butadiene and isoprene, the 1,4-additional structure of butadiene and isoprene in the microstructure of the block Q is formed. , 20 to 100% by mass and 60 to 100% by mass, respectively.

In either case, by setting the ratio of the 1,4-additional structure to the above range, the adhesive property of the obtained modified polyolefin composition tends to decrease and the elastic property tends to increase. The ratio of 1,4-additional structures (hereinafter, may be referred to as “1,4-microstructure ratio”) can be measured by ^{13 C-NMR.}

The component (B3) in the present invention is not particularly limited as long as it has a structure having at least two polymer blocks P and at least one polymer block Q, and may be linear, branched, radial or the like. Although it may be used, it is preferably a block copolymer represented by the following formula (2) or (3). Further, the block copolymer represented by the following formula (2) or (3) is more preferably a hydrogenated block copolymer obtained by hydrogenation. When the copolymer represented by the following formula (2) or (3) is a hydrogenated block copolymer, the thermal stability is improved.

P- (QP) m (2)
(PQ) n (3)
(In the formula, P represents the polymer block P, Q represents the polymer block Q, m represents an integer of 1 to 5, and n represents an integer of 2 to 5.)

In the formula (2) or (3), m and n should be larger in terms of lowering the order-disorder transition temperature as a rubber polymer, but smaller in terms of ease of manufacture and cost. good.

When the component (B3) is a hydrogenated block copolymer represented by the formula (2) or (3) and the block Q is composed of butadiene, 1,4-addition of butadiene in the microstructure of the block Q is added. The structure is preferably 20 to 100% by mass. Similarly, when the block Q is composed of isoprene, the 1,4-addition structure of isoprene in the microstructure of the block Q is preferably 60 to 100% by mass. Similarly, when block Q is composed of butadiene and isoprene, the 1,4-additional structures of butadiene and isoprene in the microstructure of block Q may be 20-100% by mass and 60-100% by mass, respectively. preferable. In either case, by setting the 1,4-microstructure ratio in the above range, the adhesive property of the obtained modified polyolefin composition tends to decrease and the elastic property tends to increase.

As a block copolymer and / or a hydrogenated block copolymer (hereinafter, may be referred to as "(hydrogenated) block copolymer"), it is represented by the formula (3) because it has excellent rubber elasticity. The (hydrogenated) block copolymer represented by the formula (2) is preferable to the (hydrogenated) block copolymer, and the (hydrogenated) block represented by the formula (2) having m of 3 or less is preferable. A copolymer is more preferable, and a block copolymer represented by the formula (2) in which m is 2 or less is more preferable (hydrogenated), and a block copolymer represented by the formula (2) in which m is 1 is more preferable (hydrogenated). Block copolymers are most preferred.

The mass ratio of the block P and the block Q constituting the component (B3) is arbitrary, but the block P is more common in terms of the mechanical strength and the heat fusion strength of the flame-retardant polyolefin resin composition of the present invention. On the other hand, it is preferable that the block P is small in terms of flexibility, shape extrusion moldability, and bleed-out suppression.

The mass ratio of the block P in the component (B3) is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 30% by mass or more, and preferably 60% by mass or less, more preferably. It is 50% by mass or less, more preferably 45% by mass or less.

The method for producing the component (B3) in the present invention may be any method as long as the above-mentioned structure and physical properties can be obtained, and is not particularly limited. Specifically, for example, it can be obtained by performing block polymerization in an inert solvent using a lithium catalyst or the like by the method described in Japanese Patent Publication No. 40-23798. Further, hydrogenation (hydrogenation) of block copolymers is performed, for example, in JP-A-42-8704, JP-A-43-6636, JP-A-59-133203 and JP-A-60-79005. Etc. can be carried out in the presence of a hydrogenation catalyst in an inert solvent. In this hydrogenation treatment, 50% or more of the olefinic double bonds in the polymer block are preferably hydrogenated, 80% or more are more preferably hydrogenated, and in the polymer block. It is preferable that 25% or less of the aromatic unsaturated bond of the above is hydrogenated.

Ingredient (B3) is available as a commercial product. Examples of commercially available products include TSRC's "TAIPOL series", Kraton's "KRATON (registered trademark) -G series", and Kraton's "Septon (registered trademark)" as hydrogenated block copolymers. ) Series ”,“ Hybler (registered trademark) series ”,“ Tough Tech (registered trademark) series ”and“ Asaplen (registered trademark) series ”manufactured by Asahi Kasei Co., Ltd. Commercially available non-hydrogenated block copolymers include Kraton Polymer's "KRATON (registered trademark) -A series", Kuraray's "Hybler (registered trademark) series", and Asahi Kasei's "Toughpren (registered trademark)". "Registered trademark) series" and the like.

As the component (B3), only one type may be used, or two or more types having different block compositions, physical properties, etc. may be mixed and used.

When the component (B) contains the component (B3), the content of the component (B3) in 100 parts by mass of the component (B) is preferably 10 to 30 parts by mass, particularly preferably 15 to 25 parts by mass. When the ratio of the component (B3) is at least the above lower limit, it is preferable from the viewpoint of moldability, and when it is at least the above upper limit, it is preferable from the viewpoint of heat resistance.

[Content ratio of component (A) and component (B)]
The mixture of the present invention contains 40 to 80 parts by mass, particularly 30 to 70 parts by mass, and particularly 20 to 60 parts by mass of the component (B) with respect to a total of 100 parts by mass of the component (A) and the component (B). Is preferable. That is, from the viewpoint of moldability of the flame-retardant polyolefin resin composition of the present invention, the component (B) is preferably not more than the above lower limit and preferably not more than the above upper limit from the viewpoint of moldability.

[Component (C)]
The mixture of the present invention contains the following component (C) from the viewpoint of improving moldability.
Ingredient (C): Softening agent for paraffinic rubber

Examples of commercially available hydrocarbon-based softeners for hydrocarbons include mineral oil-based softeners and synthetic resin-based softeners, but mineral oil-based softeners are preferable from the viewpoint of compatibility with other components. Mineral oil-based softeners are generally a mixture of aromatic hydrocarbons, naphthenic hydrocarbons and paraffinic hydrocarbons, and paraffinic oils in which 50% or more of all carbon atoms are paraffinic hydrocarbons. Those in which 30 to 45% of all carbon atoms are naphthenic hydrocarbons are called naphthenic oils, and those in which 35% or more of all carbon atoms are aromatic hydrocarbons are called aromatic oils. Among these, in the present invention, a paraffin-based rubber softener, which is a paraffin-based oil, is used. The paraffin-based rubber softener may be used alone or in any combination and ratio of two or more.

The kinematic viscosity of the paraffin-based rubber softener of the component (C) at 40 ° C. is not particularly limited, but is preferably 20 cSt or more, more preferably 50 cSt or more, and preferably 800 cSt or less, more preferably 600 cSt or less. .. The flash point (COC method) of the hydrocarbon softener is preferably 200 ° C. or higher, more preferably 250 ° C. or higher.

The paraffin-based rubber softener of the component (C) can be obtained as a commercially available product. Examples of applicable commercial products include Nisseki Polybutene (registered trademark) HV series manufactured by JX Nikko Nisseki Energy Co., Ltd., Diana (registered trademark) process oil PW series manufactured by Idemitsu Kosan Co., Ltd., and the like. Can be appropriately selected and used.

The content of the component (C) in the mixture of the present invention is preferably 3 parts by mass or more, more preferably 3 parts by mass or more, based on 100 parts by mass of the total of the component (A) and the component (B). Is 5 parts by mass or more, more preferably 10 parts by mass or more. The content of the component (C) is preferably 50 parts by mass or less, more preferably 40 parts by mass, based on 100 parts by mass of the total of the component (A) and the component (B) from the viewpoint of low temperature impact resistance. It is not less than parts by mass, and more preferably 30 parts by mass or less.

[Component (D)]
The flame-retardant polyolefin resin composition of the present invention is obtained by dynamically cross-linking in the presence of a cross-linking agent. By this dynamic cross-linking treatment, the flame-retardant polyolefin resin composition of the present invention has good heat resistance and moldability.

The cross-linking agent of the component (D) used for this dynamic cross-linking treatment consists of an organic peroxide and a cross-linking aid, and these organic peroxides and the cross-linking aid may be used alone or in combination of two or more. Can also be used in combination.

As the organic peroxide that can be used as a cross-linking agent, either an aromatic organic peroxide or an aliphatic organic peroxide can be used. Specifically, di-t-butylperoxide, t-butylcumylperoxide, dicumylperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl. -2,5-di (t-butylperoxy) hexin-3,1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-di (t-butylperoxy) -3,3,5 Dialkyl peroxides such as -trimethylcyclohexane; t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2 Peroxyesters such as 5-di (benzoyl peroxy) hexin-3; hydropers such as acetyl peroxide, lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, etc. Examples include oxides. Among these, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane is preferable. These organic peroxides may be used alone or in combination of two or more.

Examples of the cross-linking aid include peroxide aids for peroxides such as sulfur, p-quinonedioxime, p-dinitrosobenzene, and 1,3-diphenylguanidine; stannous chloride / anhydride, stannous chloride. Cross-linking aids for phenolic resins such as dihydrate and ferric chloride; polyfunctional vinyl compounds such as divinylbenzene, triallyl cyanurate, triallyl isocyanurate and diallyl phthalate; ethylene glycol di (meth) acrylate, diethylene glycol di Examples thereof include polyfunctional (meth) acrylate compounds such as (meth) acrylate, polyethylene glycol di (meth) acrylate, trimethylpropantri (meth) acrylate, and allyl (meth) acrylate. These may be used alone or in combination of two or more.
Of these, it is particularly preferable to include divinylbenzene from the viewpoint of good progress of the reaction of dynamic cross-linking.

In the flame-retardant polyolefin resin composition of the present invention, the amount of the organic peroxide used as the component (D) is crosslinked with respect to a total of 100 parts by mass of the component (A), the component (B) and the component (C). From the viewpoint of sufficiently advancing the reaction, it is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and further preferably 0.3 parts by mass or more. On the other hand, the amount of the organic peroxide used is preferably 10 parts by mass or less from the viewpoint of controlling the crosslinking reaction with respect to a total of 100 parts by mass of the component (A), the component (B) and the component (C). It is more preferably 8 parts by mass or less, further preferably 6 parts by mass or less, and particularly preferably 4 parts by mass or less.
When divinylbenzene is used as the cross-linking aid for the component (D), the amount used is 0.1 to 2% by mass with respect to a total of 100 parts by mass of the component (A), the component (B) and the component (C). Parts, particularly 0.2 to 1 part by mass, are preferable from the viewpoint of moldability.

[Component (E)]
In the present invention, a flame retardant is used as the component (E) in order to obtain flame retardancy as a flame-retardant polyolefin resin composition.
The flame retardant of the component (E) is not particularly limited, but a brominated flame retardant and / or an antimony flame retardant is suitable.

Examples of the brominated flame retardant include aromatic bromine compounds, brominated epoxy resins, brominated polycarbonates, brominated aromatic vinyl copolymers, brominated cyanurate resins, brominated polyphenylene ethers, and the like, and specific examples are ethylene. Bis (pentabromobenzene), decabromodiphenyl oxide, ethylene bistetrabromophthalimide, poly (pentabromobenzyl acrylate), tetrabrom bisphenol A, tetrabromo bisphenol A oligomer, brominated bisphenol epoxy resin, brominated bisphenol phenoxy Examples thereof include resins, brominated polystyrenes such as brominated bisphenol polycarbonates and polydibromostyrenes, brominated polyphenylene oxides such as brominated crosslinked polystyrenes and polydibromphenylene oxides, decabromdiphenyloxide bisphenol condensates and halogenated phosphoric acid esters. .. The bromine content in the brominated flame retardant is preferably 60% by mass or more, more preferably 80% by mass or more. Ethylene bis (pentabromobenzene) is preferable as the brominated flame retardant having a bromine content of 80% by mass or more.

Examples of the antimony-based flame retardant include antimony trioxide, antimony pentoxide, and anhydrous sodium antimonate, and among them, antimony trioxide is preferable.

One type of each of the antimony-based flame retardant and the antimony-based flame retardant may be used, or two or more types may be used. One or two kinds of brominated flame retardants and one or more kinds of antimony flame retardants may be used in combination.

The flame retardant of the component (E) is preferably used in an amount of 30 to 80 parts by mass, more preferably 40 to 70 parts by mass, based on 100 parts by mass of the total of the component (A) and the component (B). If the amount of the flame retardant is less than the above lower limit, sufficient flame retardancy cannot be obtained, and if it is more than the above upper limit, the moldability tends to deteriorate.

[Other ingredients]
In addition to the components (A) to (E), the mixture of the present invention may contain other components as necessary, as long as the effects of the present invention are not impaired.

Examples of other components include thermoplastic resins other than the components (A) and (B), resins such as elastomers, antioxidants, fillers, heat stabilizers, light stabilizers, ultraviolet absorbers, neutralizers, and the like. Lubricants, antifogging agents, anti-blocking agents, slip agents, dispersants, colorants, antistatic agents, conductivity-imparting agents, metal inactivating agents, molecular weight modifiers, antibacterial agents, fungicides, fluorescent whitening agents Various additives such as and the like can be mentioned. Any of these can be used alone or in combination.

Examples of the thermoplastic resin other than the components (A) and (B) include polyphenylene ether resin; polyamide resin such as nylon 6 and nylon 66; polyester resin such as polyethylene terephthalate and polybutylene terephthalate; polyoxymethylene homo. Polyoxymethylene resins such as polymers and polyoxymethylene copolymers; polymethylmethacrylate resins, polyolefin resins (excluding those corresponding to component (A) or component (B)) and the like can be mentioned. Examples of the elastomer other than the components (A) and (B) include styrene-based elastomer; polyester-based elastomer; and polybutadiene.

Examples of the antioxidant include a phenol-based antioxidant, a sulfide-based antioxidant, a thioether-based antioxidant, and the like. When an antioxidant is used, it is usually used in the range of 0.01 to 3.0 parts by mass with respect to a total of 100 parts by mass of the component (A), the component (B) and the component (C).

Examples of the filler include glass fiber, hollow glass ball, carbon fiber, talc, calcium carbonate, mica, potassium titanate fiber, silica, metal soap, titanium dioxide, carbon black and the like. When a filler is used, it is usually used in an amount of 0.1 to 50 parts by mass with respect to a total of 100 parts by mass of the component (A), the component (B) and the component (C).

[Manufacturing method of flame-retardant polyolefin resin composition]
The flame-retardant polyolefin resin composition of the present invention is obtained by dynamically cross-linking a mixture of the present invention containing a predetermined amount of the components (A) to (E) and other components used as needed. It is a thing.

In the present invention, "dynamic cross-linking" means kneading in a molten state or a semi-melted state in the presence of a cross-linking agent which is a component (D). This dynamic cross-linking is preferably performed by melt-kneading, and as a mixing-kneading device for that purpose, for example, a non-open type Banbury mixer, a mixing roll, a kneader, a twin-screw extruder or the like is used. Among these, it is preferable to use a twin-screw extruder. A preferred embodiment of the manufacturing method using this twin-screw extruder is to supply each component to a raw material supply port (hopper) of a twin-screw extruder having a plurality of raw material supply ports to perform dynamic cross-linking.

The temperature at which the dynamic cross-linking is performed is usually 80 to 300 ° C, preferably 100 to 250 ° C. The time for performing the dynamic heat treatment is usually 0.1 to 30 minutes.

[Molded body / use]
The flame-retardant polyolefin-based resin composition of the present invention is usually formed into a molded product by various molding methods such as injection molding, extrusion molding, hollow molding, and compression molding, which are usually used for the polyolefin-based resin composition. Of these, injection molding and extrusion molding are preferable. Further, it is also possible to obtain a molded product obtained by performing secondary processing such as laminating molding and thermoforming after performing these moldings. In particular, the flame-retardant polyolefin resin composition of the present invention is excellent in extrusion moldability and is suitable for extrusion molding, especially irregular shape extrusion molding, because it reduces the occurrence of rheumatism and bumps during molding. ..

The flame-retardant polyolefin resin composition of the present invention can be used in a wide range of fields such as electric wires; electric wire protection tubes; tubes; miscellaneous goods. Among those listed above, the thermoplastic elastomer composition of the present invention is particularly suitable as an electric wire coating material.

Hereinafter, the content of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded. The values of various production conditions and evaluation results in the following examples have meanings as preferable values of the upper limit or the lower limit in the embodiment of the present invention, and the preferable ranges are the above-mentioned upper limit or lower limit values and the following. It may be in the range specified by the value of Examples or the combination of the values of Examples.

[material]
The raw materials used in the following examples and comparative examples are as follows.

[Ingredient (A)]
A1:
Propylene random copolymer; specific gravity: 0.90 g / cm ³ , MFR (230 ° C, 21.2 N load): 0.8 g / 10 minutes, melting end temperature: 150 ° C, ethylene content in rubber: 0% by mass , Japan Polypropylene Corporation Novatec PP (registered trademark) EG8B
A2:
Propylene-ethylene block copolymer-1; specific gravity: 0.90 g / cm ³ , MFR (230 ° C, 21.2 N load): 1.5 g / 10 minutes, melting end temperature: 170 ° C, ethylene content in rubber : 80% by mass, 140 ° C. soluble content: 70% by mass, 100 ° C. soluble content: 30% by mass, Novatec PP (registered trademark) EC7 manufactured by Nippon Polypro Co., Ltd.
A3:
Propylene-ethylene block copolymer-2; specific gravity: 0.90 g / cm ³ , MFR (230 ° C, 21.2 N load): 0.5 g / 10 minutes, melting end temperature: 170 ° C, ethylene content in rubber : 83% by mass, 140 ° C. soluble content: 77% by mass, 100 ° C. soluble content: 23% by mass, Novatec PP (registered trademark) EC9 manufactured by Nippon Polypro Co., Ltd.
A4:
Propylene-ethylene block copolymer-3; specific gravity: 0.90 g / cm ³ , MFR (230 ° C, 21.2 N load): 2.7 g / 10 minutes, melting end temperature: 165 ° C, ethylene content in rubber : 91% by mass, 140 ° C. soluble content: 73% by mass, 100 ° C. soluble content: 27% by mass, Novatec PP (registered trademark) BC6 manufactured by Nippon Polypro Co., Ltd.

<Ingredient (B)>
B1:
Ethylene-α-olefin-non-conjugated diene copolymer (EPDM-1); Mooney viscosity (ML _{1 + 4} , 125 ° C.): 61, ethylene unit content: 66% by mass, ethylidene norbornene unit content: 5.0% by mass ), EP3092PM manufactured by Mitsui Chemicals, Inc.
Ethylene-α-olefin-non-conjugated diene copolymer B2:
Ethylene-α-olefin-non-conjugated diene copolymer (EPDM-2); Mooney viscosity (ML _{1 + 4} , 125 ° C.): 64, ethylene unit content: 67% by mass, ethylidene norbornene unit content: 4.5% by mass ), JSR Corporation EP505EC
B3:
Hydrogenated styrene-butadiene block copolymer (SEBS); Specific gravity: 0.91 g / cm ³ , Styrene unit content: 33% by mass, TSRC TAIPOL SEBS-6151

<Component (C)>
C1:
Softener for paraffinic rubber; kinematic viscosity at 40 ° C: 95.5 cSt, pour point: -15 ° C, flash point: 272 ° C), Diana Process Oil PW90 manufactured by Idemitsu Kosan Co., Ltd.

<Crosslinking agent>
D1:
Crosslinking aid; a mixture of 60% by mass of divinylbenzene and 40% by mass of ethylvinylbenzene, divinylbenzene D2 manufactured by Wako Pure Chemical Industries, Ltd .:
Organic peroxide; a mixture of 40% by mass of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 60% by mass of calcium carbonate, Kayahexa AD40C manufactured by Kayaku Akzo Corporation

<Flame retardant>
E1:
Bromine-based flame retardant; ethylenebis (pentabromobenzene) (bromine content 82% by mass), SAYTEX8010 manufactured by Albemarle Corporation
E2:
Antimony flame retardant; Antimony trioxide, PATOX-KN manufactured by Nihon Seiko Co., Ltd.

[Evaluation method]
The evaluation method of the flame-retardant polyolefin resin composition in the following Examples / Comparative Examples is as follows.

<PP characteristics>
<Melting end temperature>
The melting end temperature was measured according to JIS K7121 by the following method. That is, the following steps (1) to (3) are sequentially carried out using a differential scanning calorimeter (DSC6220 manufactured by SSI Nanotechnology Co., Ltd.) to carry out the following steps (1) to (3) in order, and the polypropylene resin (here, the polypropylene resin is A1 in the table). ~ A4 component.) The melting behavior is measured. In each process, time is plotted on the horizontal axis and heat of fusion is plotted on the vertical axis to obtain a melting curve, and the outer peak end point (° C) of the peak observed in step (3) is calculated and used as the melting point end point. ..
Step (1): The temperature of 5 mg of the sample is raised from room temperature to 100 ° C./min at a rate of 40 ° C. to 200 ° C., and the temperature is maintained for 3 minutes after the temperature rise is completed.
Step (2): The temperature is lowered from 200 ° C. to 40 ° C. at a rate of 10 ° C./min, and the temperature is maintained for 3 minutes after the temperature reduction is completed.
Step (3): The temperature is raised from 40 ° C. to 200 ° C. at a rate of 10 ° C./min.

<Ethylene content in rubber>
The ethylene content in the rubber was measured as follows. Cross sorting device as a measuring device (CFC manufactured by Dia Instrument)
T101) was used. This cross-separator has a temperature-increasing elution separation (TREF) mechanism that separates samples using the difference in dissolution temperature, and a size exclusion chromatograph (SEC) that further separates the separated divisions by molecular size. Connected online.
First, the sample to be measured is dissolved at 140 ° C. using a solvent (o-dichlorobenzene) so as to be 3 mg / ml, and this is injected into the sample loop in the measuring device. The following measurements are made automatically according to the set conditions. The sample solution held in the sample loop is placed on a TREF column (a stainless steel column with an inner diameter of 4 mm and a length of 150 mm filled with glass beads, which is an inert carrier) that separates the sample solution using the difference in dissolution temperature. Inject 0.4 ml. The sample is then cooled to a temperature of 140 ° C. to 0 ° C. at a rate of 1 ° C./min and coated on the Inactive Carrier. At this time, a polymer layer is formed on the surface of the inert carrier in the order of high crystal component (easy to crystallize) to low crystal component (hard to crystallize). After the TREF column is held at 0 ° C. for another 30 minutes, 2 ml of the component dissolved at the temperature of 0 ° C. is injected from the TREF column to the SEC column (3 AD806MS manufactured by Showa Denko) at a flow rate of 1 ml / min. .. During the molecular size fractionation in the SEC, the TREF column is heated to the next elution temperature (5 ° C.) and held at that temperature for about 30 minutes. Measurements of each elution category at SEC were performed at 39 minute intervals. The elution temperature is gradually raised at a lower temperature.
0,5,10,15,20,25,30,35,40,45,49,52,55,58,61,64,67,70,73,76,79,82,85,88,91, 94,97,100,102,120,140 ° C
The absorbance of the solution sorted by molecular size on the SEC column was measured by the infrared spectrophotometer attached to the device in proportion to the concentration of the polymer (wavelength 3.42 μm, detected by expansion and contraction vibration of methylene), and each elution temperature category was determined. A chromatogram is obtained. Using the built-in data processing software, the baseline of the chromatogram of each elution temperature category obtained in the above measurement is drawn and arithmetically processed. The area of each chromatogram is integrated and the integrated elution curve is calculated. Further, the differential elution curve is calculated by differentiating this integral elution curve with temperature. The portion eluted up to this point was defined as the total rubber content. The elution portion was concentrated, IR measurement was performed, and the ratio of ethylene to propylene was calculated.

<140 ° C soluble content>
From the integrated elution curve of TREF obtained above, the rate of elution in the region of 100 to 140 ° C. was calculated as the 140 ° C. soluble content.

<100 ° C soluble content>
From the integrated elution curve of TREF obtained above, the rate of elution in the region of 0 to 100 ° C. was calculated as the 100 ° C. soluble content.

<Oil resistance test>
A No. 3 dumbbell piece punched out from an extruded tape (thickness 1 mm) was immersed in an oil (made by Sun Oil Co., Ltd., IRM902) adjusted to 60 ° C. for 168 hours. Then, the adhering oil is wiped off, and the mixture is kept in an environment of 23 ° C. and 50% RH for 24 hours, and then JIS.
The tensile strength and tensile elongation were measured according to C-3005. The tensile speed was 200 mm / min.
Using the value of the tensile test not immersed in oil as a reference (100%), the retention rates of each of the tensile strength and the tensile elongation were calculated and used as the tensile strength residual ratio and the tensile elongation residual ratio, respectively. It is preferable that both the tensile strength residual ratio and the tensile elongation residual ratio have high values.

<Heat deformation rate>
The heat deformation rate was measured according to JIS K6723 using a press sheet having a thickness of 2 mm.
The test conditions were set temperature; 150 ° C., weighting; 2 kgf, weighting time: 1 hour, and the rate of change in the thickness of the press sheet before the test and the thickness after the test was measured. It is preferable that the rate of change in thickness is small.

<A hardness>
A 2 mm thick press sheet was stacked on top of each other, and the A hardness was measured according to JIS K6253 (JIS-A).

<Flame retardant test>
A test piece (length: 127 mm, width: 12.7 mm, thickness: 3 mm) obtained from a 3 mm thick press sheet was kept vertical, and a burner was indirectly ignited at the lower end for 10 seconds, and then the flame was removed. The time for extinguishing the fire that ignited the test piece was measured. Then, at the same time as the fire was extinguished, the second flame contact was performed for 10 seconds, and the time for extinguishing the ignited fire was measured in the same manner as the first time. Furthermore, it was also evaluated whether or not the cotton placed under the test piece was ignited by the falling fire type.
The flammability was evaluated according to the UL-94V standard from the results of the first and second burning times and the presence or absence of cotton ignition. Combustion performance is good in the order of V-0>V-1> V-2.

<Extruded tape appearance>
The appearance of the extruded tape was observed, the surface was smooth, and the evaluation was made in the following three stages based on the number of lumps and the size of the lumps.
◎: Excellent 〇: Good ×: Bad

[Examples 1 to 3, Comparative Examples 1 and 2]
Each component shown in Table-1 is inserted into a pressurized kneader having an internal volume of 1.0 L at the ratio shown in Table-1, kneaded at the jacket set temperature of the pressurized kneader at 80 to 170 ° C., and the resin temperature is generated by self-heating by shearing. The kneading was completed when the temperature reached 190 ° C. This dynamic cross-linking treatment time is 20 minutes. The obtained kneaded product was further sheeted by an open roll having a surface temperature of 140 ° C. and then pelletized with a pelletizer to prepare a resin composition.

Using the obtained pellets, a sheet having a thickness of 2 to 3 mm is formed by an open roll having a surface temperature of 140 ° C., and then a sheet having a thickness of 2 mm or 3 mm is formed by press molding (temperature 190 ° C., pressure 10 MPa) to form a press sheet. Got Table 1 shows the results of the heat deformation rate, A hardness, and flame retardancy test of the press sheet by the above-mentioned method.
Further, the obtained pellets were extruded at 200 ° C. using a 20 mm single-screw extruder to obtain an extrusion tape having a width of 50 mm and a thickness of 1 mm. Table 1 shows the results of the extrusion tape appearance, tensile test, and oil resistance test of the extruded tape by the above-mentioned method.
The PP characteristics in Table 1 show the following values.

[Evaluation results]
As shown in Table 1, the heating deformation rate of Examples 1 to 3 is 8 to 19%, the heating deformation rate of Comparative Examples 1 and 2 is 20 to 100%, and Examples 1 to 3 are Comparative Example 1. It showed a low heating deformation rate as compared with ~ 2. In the evaluation of "heat deformation rate", it can be seen that Examples 1 to 3 have excellent heat resistance. Further, in Example 3 in which a part of the propylene-ethylene block copolymer in Example 2 was replaced with a propylene random copolymer, the tensile strength residual ratio and the tensile elongation residual ratio were higher in the "oil resistance test" than in Example 2. showed that. From this, it can be seen that the oil resistance at high temperature is excellent. Further, as a result of the evaluation of "extruded tape appearance", the surface of Example 3 was the smoothest, the number of lumps was small, and the size of lumps scattered was larger than that of Examples 1 and 2 and Comparative Examples 1 and 2. It was also small. Therefore, the molded product obtained from Example 3 is likely to have a good appearance and is considered to be excellent in productivity.

Further, in Comparative Example 1, the melting end temperature of the propylene-ethylene block copolymer or the propylene random copolymer is lower than that of Examples 1 to 3. Further, the ethylene content in the rubber is low, and the soluble content at 100 ° C. is high. Therefore, it can be seen that the evaluation of the "heat deformation rate", which is an index of heat resistance, is inferior.

The flame-retardant polyolefin resin composition of the present invention can be used in a wide range of fields such as electric wires; electric wire protection tubes; tubes; miscellaneous goods. Among those listed above, the flame-retardant polyolefin resin composition of the present invention is particularly suitable as an electric wire coating material.

Claims (11)

A flame-retardant polyolefin resin composition obtained by dynamically cross-linking a mixture containing the following components (A) to (E).
Component (A): Olefin-based polymer component (B) containing a propylene-ethylene block copolymer having a melting end temperature of 166 to 175 ° C .: Thermoplastic resin component (C) containing an ethylene-α-olefin copolymer: Softener component for paraffin rubber (D): Cross-linking agent component (E): Flame retardant The flame-retardant polyolefin resin according to claim 1, wherein the MFR (230 ° C., 21.2 N load) of the propylene-ethylene block copolymer in the component (A) is 0.05 to 2.0 g / 10 minutes. Composition. The flame-retardant polyolefin resin composition according to claim 1 or 2, wherein the component (A) contains a propylene random copolymer. The flame-retardant polyolefin resin composition according to any one of claims 1 to 3, wherein the ethylene content of the propylene-ethylene block copolymer in the component (A) in the rubber is 72 to 90% by mass. .. The flame-retardant polyolefin resin according to any one of claims 1 to 4, wherein the component (B) contains an ethylene-α-olefin-non-conjugated diene copolymer having an ethylene unit content of 50 to 75% by mass. Composition. The flame-retardant polyolefin resin composition according to claim 5, wherein the component (B) contains the following component (B3).
Component (B3): A block copolymer having at least two polymer blocks P derived from a vinyl aromatic compound and at least one polymer block Q derived from conjugated diene and / or isobutylene, and the blocks. At least one block copolymer in the group consisting of block copolymers obtained by hydrogenating a copolymer. The flame-retardant polyolefin resin composition according to any one of claims 1 to 6, wherein the ratio of the component (B) to a total of 100 parts by mass of the component (A) and the component (B) is 40 to 80 parts by mass. thing. The flame-retardant polyolefin resin composition according to any one of claims 1 to 7, wherein the component (D) contains an organic peroxide and a cross-linking aid. The component (E) is a brominated flame retardant and / or an antimony flame retardant, and the ratio of the component (E) to a total of 100 parts by mass of the component (A) and the component (B) is 30 to 80 parts by mass. The flame-retardant polyolefin resin composition according to any one of claims 1 to 3. A molded product obtained by molding the flame-retardant polyolefin resin composition according to any one of claims 1 to 9. The molded body according to claim 10, which is an electric wire covering material.