JP2023117163A - Flame-retardant ethylenic polymer composition - Google Patents

Abstract

To provide a flame-retardant ethylenic polymer composition that achieves both of high flame retardancy and tensile characteristics.SOLUTION: A flame-retardant ethylenic polymer composition comprises the following components (A)-(C). In the flame-retardant ethylenic polymer composition 100 mass%, the content of the component (C) is 0.1-50 mass%. There is also provided a molding comprising the flame-retardant ethylenic polymer composition. The component (A) is a metalhydroxide. The component (B) is silicone. The component (C) is a modified polyethylene with a density of 0.85 g/cm3 or more and 0.90 g/cm3 or less.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a flame-retardant ethylene-based polymer composition and a molded article using this flame-retardant ethylene-based polymer composition.

BACKGROUND ART Polyvinyl chloride resin compositions are widely used for electric wire coatings, tubes, tapes, building materials, automobile parts, home appliance parts, and the like, because of their excellent electrical insulation and self-extinguishing flame retardancy. However, since the polyvinyl chloride resin composition contains chlorine, hydrogen chloride gas, which is a corrosive gas, is generated during combustion, and toxic gases such as dioxins may be generated depending on the combustion conditions. For this reason, as part of measures against environmental problems, materials that do not contain halogen and that have almost no possibility of generating these toxic gases when burned (hereinafter, not containing halogen may be referred to as "non-halogen"). are coming into use.

Examples of non-halogen materials include polyolefin resins such as polypropylene and polyethylene, and styrene resins. However, since polyolefin-based resins and the like are not flame-retardant, they need to be made flame-retardant depending on the application. As a countermeasure, a method of adding a halogen-based flame retardant has long been used. However, since halogen-based flame retardants also have the potential to generate toxic gases when burned, recently, as non-halogen-based flame retardants, metal hydroxides such as magnesium hydroxide and aluminum hydroxide are used. there is

For example, by using a polyolefin resin such as polyethylene, magnesium hydroxide, which is a metal hydroxide, as a flame retardant, and silicone oil as a flame retardant aid, the amount of metal hydroxide added can be kept to a minimum, and mechanical properties can be improved. There is known a technique for improving the oxygen index while suppressing the decrease in the oxygen index (Patent Document 1). Also known is a technique of adding a maleic anhydride-modified resin together with a metal hydroxide to a polyolefin resin (Patent Documents 2 and 3).

JP 2021-134342 A JP-A-10-7913 JP 2017-57274 A

However, the polyolefin-based flame-retardant resin compositions containing metal hydroxides such as magnesium hydroxide and aluminum hydroxide in Patent Documents 1 to 3 are filled with flame retardants to obtain the required flame-retardant performance. Due to the influence of , there is still room for improvement in terms of tensile properties, and flame retardancy is still insufficient.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a flame-retardant ethylene-based polymer composition capable of achieving both excellent flame retardancy and tensile properties.

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that an ethylene-based polymer composition containing a specific content of a metal hydroxide, a silicone, and a modified polyethylene having a specific density is an excellent flame retardant. It has been found that both flame resistance and tensile properties can be achieved. The present invention has been accomplished based on these findings, and the gist thereof is as follows.

[1] A flame-retardant ethylene polymer composition containing the following components (A) to (C), wherein the content of component (C) in 100% by mass of the flame-retardant ethylene polymer composition is 0 .1 to 50% by mass of a flame-retardant ethylene-based polymer composition;
Component (A): Metal hydroxide Component (B): Silicone component (C): Modified polyethylene having a density of 0.85 g/cm ³ or more and 0.90 g/cm ³ or less

[2] The flame-retardant ethylene-based polymer composition according to [1], wherein the content of component (C) in 100% by mass of the flame-retardant ethylene-based polymer composition is 0.1 to 25% by mass. .

[3] A molded article using the flame-retardant ethylene polymer composition according to [1] or [2].

According to the present invention, it is possible to provide a flame-retardant ethylene-based polymer composition having both excellent flame retardancy and tensile properties.

Although the present invention will be described in detail below, the present invention is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention. In this specification, when a numerical value or a physical property value is sandwiched before and after the "~", it is used to include the values before and after it.

[Flame-retardant ethylene-based polymer composition]
The flame-retardant ethylene-based polymer composition of the present invention is a flame-retardant ethylene-based polymer composition containing the following components (A) to (C), and 100 masses of the flame-retardant ethylene-based polymer composition %, the content of component (C) is 0.1 to 50% by mass.
Component (A): Metal hydroxide Component (B): Silicone component (C): Modified polyethylene having a density of 0.85 g/cm ³ or more and 0.90 g/cm ³ or less

[Ethylene polymer other than component (C)]
The ethylene-based polymer composition means that the ethylene-based polymer is the main component as the resin component contained in the ethylene-based polymer composition, that is, the mass ratio of the ethylene-based polymer in the resin component is the largest. It is. Therefore, the flame-retardant ethylene-based polymer composition of the present invention should have the highest mass ratio of the ethylene-based polymer in the resin component, and the flame-retardant ethylene-based polymer composition of the present invention contains ethylene as the resin component. Resins other than the polymer, for example, thermoplastic resins and elastomers exemplified later as other components, such as propylene-based polymers and styrene-based polymers, may be contained.

The ethylene-based polymer, which is the main component of the resin component contained in the flame-retardant ethylene-based polymer composition of the present invention, includes a modified polyethylene as the component (C) described later and an ethylene-based polymer other than the modified polyethylene as the component (C). It is a polymer.
In addition, the ethylene-based polymer means a polymer or copolymer containing ethylene as a main component as a raw material monomer, preferably containing 50% by mass or more of ethylene units, even if it has a partially crosslinked structure. good.

The density of the ethylene-based polymer other than component (C) (according to JIS K6922-1,2:1997) is not particularly limited, but is preferably 0.85 g/cm ³ or more, more preferably 0.87 g/cm ³ . On the other hand, it is preferably 0.90 g/cm ³ or less, more preferably 0.89 g/cm ³ or less.

In addition, the melt flow rate (MFR, JIS K7210: compliant with 1999, 190° C., load 21.2 N) of the ethylene polymer other than the component (C) is not particularly limited, but from the standpoint of moldability, it is 0.1. ~50 g/10 min is preferred, more preferably 1 to 30 g/10 min.

Ethylene-based polymers other than component (C) include ethylene/α-olefin copolymers, various polyethylenes, ethylene/vinyl acetate copolymers, and the like.

An ethylene/α-olefin copolymer is a copolymer of ethylene and an α-olefin. -butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-tetradecene, 1-octadecene. These α-olefins can be used singly or as a mixture of two or more. In addition, the ethylene/α-olefin copolymer contains vinyl esters (vinyl acetate, etc.), unsaturated carboxylic acids or their esters (acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, etc.) as copolymer components. etc.), etc. (except those corresponding to component (C) described later).

Commercially available ethylene/α-olefin copolymers include, for example, “Engage” (registered trademark) manufactured by The Dow Chemical Company and “Kernel” (registered trademark) manufactured by Japan Polyethylene Co., Ltd. It can be selected and used as appropriate.

Polyethylene includes various polyethylenes such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE).

Commercially available polyethylene includes, for example, "Novatec LL" (registered trademark) manufactured by Japan Polyethylene Co., Ltd., and can be appropriately selected and used.

An ethylene/vinyl acetate copolymer means a copolymer having at least units derived from ethylene and units derived from vinyl acetate. In the present invention, even if ethylene and vinyl acetate are not used as raw materials, copolymers that form the same chemical structure after polymerization are included in the ethylene/vinyl acetate copolymer in the present invention. .

Commercially available ethylene-vinyl acetate copolymers include, for example, "Novatec EVA" (registered trademark) manufactured by Nippon Polyethylene Co., Ltd., and "Evaflex" (registered trademark) manufactured by DuPont Mitsui Polychemicals. and "Levaprene" (registered trademark) manufactured by Lanxess, which can be selected and used as appropriate.

As the ethylene-based polymer other than the component (C), one of the various ethylene-based polymers described above may be used alone, or a mixture of two or more different copolymer component compositions and physical properties may be used. good.
For example, as the ethylene-based polymer, linear low-density polyethylene, ethylene/α-olefin copolymer, and ethylene/vinyl acetate copolymer may be appropriately mixed and used.

[Component (A)]
In the present invention, a metal hydroxide is used as component (A) in order to obtain flame retardance as a flame-retardant ethylene polymer composition.

The kind of metal hydroxide is not particularly limited, but examples thereof include magnesium hydroxide, aluminum hydroxide, zirconium hydroxide, potassium hydroxide, hydrotalcite and the like. Among them, magnesium hydroxide and aluminum hydroxide are preferably used. These metal hydroxides may be used alone, or two or more of them may be used in any combination and ratio.

The metal hydroxide used in the present invention can be surface-treated with a surface treatment agent. Examples of surface treatment agents include silane-based coupling agents, titanate-based coupling agents, fatty acids, fatty acid metal salts, and the like. Known methods such as a wet method, a dry method, and a direct kneading method can be used as methods for treating metal hydroxides with these surface treatment agents. By using a surface-treated metal hydroxide, dispersibility in the obtained flame-retardant ethylene-based polymer composition may be improved, and mechanical properties may be improved.

The average particle size of the metal hydroxide of component (A) is preferably 4 μm or less, for example 0.5 to 2 μm, from the viewpoint of mechanical properties, dispersibility and flame retardancy.

Here, the average particle size of the metal hydroxide corresponds to the average value of the diameters of spherical metal hydroxides, and can be measured by SEM observation. In the case of non-spherical metal hydroxides, it corresponds to the diameter equivalent to a sphere of equal volume. The average particle size is usually calculated as the average value of the diameters of 100 metal hydroxides obtained by such SEM observation.

The amount of the metal hydroxide of component (A) to be added to the resin component constituting the flame-retardant ethylene polymer composition of the present invention is not particularly limited, but the lower limit is usually 50 parts per 100 parts by mass of the total resin component. It is at least 80 parts by mass, preferably at least 80 parts by mass, and the upper limit is usually at most 500 parts by mass, preferably at most 400 parts by mass. By making the blending amount of the metal hydroxide equal to or higher than the above lower limit, it becomes easier to obtain the level of flame retardancy that is the object of the present invention. On the other hand, it tends to be easy to maintain workability and mechanical properties by setting the blending amount of the metal hydroxide to the upper limit value or less.

[Component (B)]
The flame-retardant ethylene polymer composition of the present invention contains silicone as component (B) from the viewpoint of improving moldability. The component (B) silicone contributes not only to the improvement of moldability but also to the improvement of flame retardancy.

Examples of the component (B) silicone include silicone oil. As the silicone oil, a silicone oil having a kinematic viscosity at 25° C. of 50 to 30,000 cSt is preferred. Here, the kinematic viscosity of silicone oil at 25° C. can be measured according to JIS Z8803.

By setting the kinematic viscosity of the silicone oil at 25°C within the above range, the effect of improving the releasability during molding can be obtained, and at the same time, the bleeding of the silicone oil to the surface of the molded product can be suppressed, and the appearance can be kept good. be able to. In order to improve these effects, the kinematic viscosity of the silicone oil at 25°C is more preferably 100 cSt or more, still more preferably 200 cSt or more, and more preferably 25,000 cSt or less. , more preferably 20,000 cSt or less, and particularly preferably 15,000 cSt or less.

As silicone oil, linear silicone represented by the following formula (1) can be preferably used.

In the above formula (1), R represents an alkenyl group and / or an organic functional group that does not participate in a hydrosilylation addition reaction such as a SiH group, or a hydroxyl group, and a plurality of R may be the same or different. good too. x represents an integer from 10 to 30,000. Each R preferably independently represents a monovalent hydrocarbon group or hydroxyl group, more preferably an alkyl group or an aryl group, still more preferably a methyl group, an ethyl group or a phenyl group.

The straight-chain silicone represented by the above formula (1) is polydiorganosiloxane having both ends blocked with triorganosilyl groups, such as polydialkylsiloxane, polydiarylsiloxane, polyalkylarylsiloxane, or a copolymer thereof. Coalescence is more preferred, polydimethylsiloxane or polymethylphenylsiloxane is more preferred, and polydimethylsiloxane in which all R are methyl groups is particularly preferred.

As polydimethylsiloxane, SH200 (manufactured by Dow Corning Toray Co., Ltd.), KF-96, KF-96H, KF-965, KF-968 (manufactured by Shin-Etsu Silicone Co., Ltd.), TSF451 (manufactured by Momentive Performance Materials Japan) ), AK, AKF, AKC (manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) and the like are commercially available. In addition, as polymethylphenylsiloxane, SH510, SH550, SH710 (manufactured by Dow Corning Toray Co., Ltd.), KF-50, KF-53, KF-54 (manufactured by Shin-Etsu Silicone Co., Ltd.), TSF431, TSF433, TSF4300 (Momentive Performance・Materials), AR (Asahi Kasei Wacker Silicone), etc. are commercially available. Furthermore, Tegomer V-Si4042 (manufactured by Evonik) and the like are commercially available as organomodified siloxanes whose functionality is enhanced by introducing an organic group onto the silicone skeleton.

Only one type of silicone oil may be used, or two or more types having different kinematic viscosities and different values of R in the formula (1) may be used in combination.

In the flame-retardant ethylene-based polymer composition of the present invention, the content of the component (B) silicone is preferably 0.1 to 8 parts by mass, more preferably 100 parts by mass in total of the resin components. is 0.5 to 6 parts by mass, more preferably 1 to 5 parts by mass, particularly preferably 2 to 5 parts by mass.

When the flame-retardant ethylene-based polymer composition of the present invention contains the component (B) silicone within the above range, the effect of blending the other components is sufficiently obtained, and the moldability and oxygen A sufficient effect of improving the index can be obtained.

[Component (C)]
The flame-retardant ethylene polymer composition of the present invention contains the following component (C) from the viewpoint of improving mechanical properties and oxygen index.
Component (C): Modified polyethylene having a density of 0.85 g/cm ³ or more and 0.90 g/cm ³ or less

Component (C) has a low crystal content and a density of 0.85 g in order to facilitate mixing with the ethylene polymer as a resin component other than component (C) and the metal hydroxide of component (A). /cm ³ or more and 0.90 g/cm ³ or less is used.

Specific examples of polyethylene used as a raw material for component (C) include ethylene homopolymers such as high-pressure low-density polyethylene (LDPE) and high-density polyethylene (HDPE), ethylene-propylene copolymers, and ethylene-butene copolymers. , ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-propylene-butene copolymer, ethylene-propylene-hexene copolymer, ethylene-propylene-octene copolymer, ethylene-butene-hexene copolymer , ethylene/butene/octene copolymers, ethylene/α-olefin copolymers such as ethylene/hexene/octene copolymers, ethylene/vinyl acetate copolymers, ethylene/(meth)acrylic acid copolymers, Ethylene-based (co)polymers such as ethylene/methyl (meth)acrylate copolymer, ethylene/ethyl (meth)acrylate copolymer, ethylene/(meth)acrylic acid/methyl (meth)acrylate copolymer, etc. etc. Here, "(co)polymer" is a generic term for polymers and copolymers, and "(meth)acrylic acid" is a generic term for acrylic acid and methacrylic acid.

Here, the ethylene-based copolymer means a copolymer containing ethylene in a proportion of 50% by mass or more of all monomer units constituting the copolymer.

These raw material polyethylenes can be used singly or in any combination and ratio of two or more.

Among these, ethylene homopolymers, ethylene/α-olefin copolymers, and ethylene/vinyl acetate copolymers, which are ethylene-based (co)polymers, are inexpensive and readily available, and are economically efficient. preferable. From the viewpoint of mechanical properties, ethylene homopolymers and ethylene/α-olefin copolymers are more preferable as raw material polyethylene.

The density of polyethylene used as a raw material for component (C) (according to JIS K6922-1, 2:1997) is not particularly limited, but is preferably 0.85 g/cm ³ or more, more preferably 0.87 g/cm ³ or more. On the other hand, it is preferably 0.90 g/cm ³ or less, more preferably 0.89 g/cm ³ or less.

In addition, the melt flow rate (MFR, JIS K7210: compliant with 1999, 190° C., load 21.2 N) of polyethylene used as a raw material for component (C) is not particularly limited, but from the standpoint of moldability, it is from 0.1 to 50 g/10 min is preferred, more preferably 1 to 30 g/10 min.

Various grades of polyethylene satisfying the above physical properties are commercially available from domestic and overseas manufacturers, and various grades of commercial products can be used as the polyethylene used as the starting material for component (C).

An unsaturated carboxylic acid is suitable as the acid used for modifying the raw material polyethylene. Examples of unsaturated carboxylic acids include, but are not limited to, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, hymic acid, and citraconic acid. Derivatives of unsaturated carboxylic acids include anhydrides, esters, amides, imides and metal salts of these acids.

Specific examples of unsaturated carboxylic acid derivatives include maleic anhydride, hymic anhydride, itaconic anhydride, citraconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, glycidyl acrylate, Glycidyl methacrylate, maleic acid monoethyl ester, maleic acid diethyl ester, itaconic acid monomethyl ester, itaconic acid diethyl ester, acrylamide, methacrylamide, maleic acid monoamide, maleic acid diamide, maleic acid-N-monoethylamide, maleic acid- N,N-diethylamide, maleic acid-N-monobutylamide, maleic acid-N,N-dibutylamide, fumaric acid monoamide, fumaric acid diamide, fumaric acid-N-monobutylamide, fumaric acid-N,N-dibutyl Amide, maleimide, N-butylmaleimide, N-phenylmaleimide, sodium acrylate, sodium methacrylate, potassium acrylate, potassium methacrylate.

Among these, (meth)acrylic acid and/or its derivatives, maleic acid and/or its derivatives, especially (meth)acrylic acid and/or its anhydride, maleic acid and/or its anhydride, have an electron density of It is suitable because it is low and highly reactive.

These acids and/or derivatives thereof may be used alone or in combination of two or more.

The amount of acid and/or derivative thereof used for modifying polyethylene is usually 0.01 parts by mass or more, preferably 0.1 parts by mass or more, relative to 100 parts by mass of polyethylene used as the starting material for component (C). On the other hand, it is usually 20 parts by mass or less, preferably 10 parts by mass or less. When the amount of the acid and/or its derivative is at least the above lower limit, the resulting thermoplastic elastomer composition tends to have good adhesiveness. By suppressing the generation of by-products, it is possible to prevent deterioration of product appearance due to fish eyes, pimples, etc., and to suppress deterioration of flame retardancy in the resulting molded article using modified polyethylene.

Modification with the acid and/or derivative thereof described above is preferably graft modification, and can be carried out by various conventionally known methods. Modification methods include a melt modification method in which acid and/or derivatives thereof are added to molten polyethylene and graft copolymerization is performed, and a solution in which acid and/or derivatives thereof are added to polyethylene dissolved in a solvent and graft copolymerization is performed. Examples include a modification method, a solid phase polymerization method in which an acid and/or a derivative thereof is added to a solid polyethylene and graft copolymerization is performed, and the like, but are not particularly limited thereto.

The rate of modification by the component (C) acid and/or derivative thereof is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.3% by mass, based on the total amount of the modified polyethylene of component (C). % or more, preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less. Although it varies depending on the polyethylene used as the raw material, flame retardancy tends to be good if the modification rate with the acid and/or its derivative is at least the above lower limit. Further, when the modification rate is equal to or less than the above upper limit, it is possible to suppress deterioration of thermal stability, and it tends to be possible to suppress deterioration of compatibility with other components.

Here, the modification rate (grafting rate) means the content rate of the acid and/or its derivative component when measured with an infrared spectrometer. For example, absorption specific to unsaturated carboxylic acids and/or derivatives thereof in a sample press-molded into a sheet with a thickness of about 100 μm, specifically carbonyl characteristic absorption at 1900 to 1600 cm ⁻¹ (C=O stretching vibration band) can be obtained by measuring In the modification with an acid and/or derivative thereof, 100% of the modified polyethylene may not be subjected to the reaction, and the acid and/or derivative thereof that has not reacted with the polyethylene may remain in the modified polyethylene. The modification rate (grafting rate) in is the value measured by the above method.

In addition, the melt flow rate (MFR) of the modified polyethylene of component (C) is not particularly limited, but is preferably 0.1 to 50 g/10 minutes, more preferably 1 to 30 g/10 minutes, still more preferably 1 ~20 g/10 min. Here, the MFR of modified polyethylene means a value measured under conditions of a measurement temperature of 190° C. and a measurement load of 21.2 N in accordance with JIS K7210 (1999).

In the measurement of the melt flow rate (MFR, JIS K7210 (1999) compliant, 190°C, load 21.2 N) of the modified polyethylene of component (C), when the fluidity is too high at 190°C and measurement is difficult. may be measured at 180° C. (21.2 N load). For example, the melt flow rate of maleic acid-modified polyethylene (MFR, compliant with JIS K7210 (1999), 180° C., load 21.2 N) is preferably 1 to 30 g/10 minutes, more preferably 1 to 20 g/10 minutes. be.

In the flame-retardant ethylene-based polymer composition raw material of the present invention, only one type of modified polyethylene may be used as component (C). Two or more kinds of derivatives having different types and modification rates may be used.

Modified polyethylene of component (C) can also use a commercial item. As a modified polyethylene that can be obtained as a commercial product, for example, a product corresponding to "Modic" (registered trademark) manufactured by Mitsubishi Chemical Corporation can be used.

In the flame-retardant ethylene-based polymer composition of the present invention, the content of the modified polyethylene having a density of component (C) of 0.85 g/cm ³ or more and 0.90 g/cm ³ or less is It is 0.1 to 50% by mass with respect to 100% by mass of the polymer composition. Although the lower limit of the modified polyethylene content is not particularly limited, it is preferably 1% by mass or more, more preferably 5% by mass or more, from the viewpoint of flame retardancy. The upper limit of the modified polyethylene content is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of achieving both flame retardancy and tensile properties.

[Other ingredients]
The flame-retardant ethylene-based polymer composition of the present invention contains various polymers and additives other than the ethylene-based polymer and components (A) to (C) within a range that does not significantly impair the effects of the present invention. can do.

Other polymers that may be contained in the flame-retardant ethylene-based polymer composition of the present invention include ethylene-based polymers, thermoplastic resins and elastomers other than the component (C).

Examples of thermoplastic resins other than ethylene-based polymers and component (C) include polyphenylene ether-based resins; polyamide-based resins such as nylon 6 and nylon 66; styrene-based resins; polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate. polyoxymethylene resins such as polyoxymethylene homopolymers and polyoxymethylene copolymers; polymethyl methacrylate resins and polyolefin resins (excluding ethylene polymers and those corresponding to component (C)). Examples of elastomers other than ethylene polymers and component (C) include styrene elastomers, polyester elastomers, and polybutadiene.

However, in the flame-retardant ethylene-based polymer composition of the present invention, the ethylene-based polymer and the component (C ), the content is preferably 20% by mass or less, preferably 10% by mass or less, in the total 100% by mass of the flame-retardant ethylene polymer composition. is more preferable.

Additives include, for example, heat stabilizers and antioxidants, lubricants, and copper inhibitors. Examples of heat stabilizers and antioxidants include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and the like. For example, "Irganox" (registered trademark) manufactured by BASF Japan series can be used. Lubricants include zinc stearate, and for example, “Zinc Stearate” (registered trademark) manufactured by Tannan Kagaku Co., Ltd. can be used. As a copper damage inhibitor, "SONNOX" (registered trademark) manufactured by Songwon International Japan can be used. These additives may be used alone, or two or more of them may be used in any combination and ratio.

When these additives are blended, the total amount of these additives is usually 2 parts by mass or less, for example 1 to 2 parts by mass, with respect to the total 100 parts by mass of the ethylene polymer and component (C). used in the range of

[Method for producing flame-retardant ethylene-based polymer composition]
The flame-retardant ethylene-based polymer composition of the present invention is prepared by kneading the mixture of the present invention containing predetermined amounts of the ethylene-based polymer, components (A) to (C), and optionally other components. It is obtained by

[Oxygen index]
The oxygen index of the flame-retardant ethylene-based polymer composition of the present invention measured according to JIS K7201 is preferably 30 to 45, more preferably 33 to 45, from the viewpoint of flame retardancy. .

[Molded product/Application]
The flame-retardant ethylene-based polymer composition of the present invention is formed into a molded body by various molding methods such as injection molding, extrusion molding, hollow molding, and compression molding, which are usually used for polyolefin-based resin compositions. be able to. Among these, injection molding and extrusion molding are preferred. In addition, it is also possible to obtain a molded body by performing secondary processing such as lamination molding and thermoforming after performing these moldings. In particular, the flame-retardant ethylene-based polymer composition of the present invention is excellent in extrusion moldability, and is suitable for extrusion molding, particularly profile extrusion molding, because it reduces the occurrence of die buildup and lumps when molded. be.

The molded article obtained from the flame-retardant ethylene polymer composition of the present invention preferably has a tensile strength of 10 to 20 MPa, more preferably 14 to 20 MPa, measured under the conditions of JIS K6723 from the viewpoint of durability. is more preferred. In addition, the molded article obtained from the flame-retardant ethylene polymer composition of the present invention preferably has a tensile elongation of 300 to 900%, measured under the conditions of JIS K6723, from the viewpoint of durability. % is more preferable.

EXAMPLES The content of the present invention will be described in more detail below using examples, but the present invention is not limited by the following examples as long as the gist thereof is not exceeded. Various production conditions and values of evaluation results in the following examples have meanings as preferred values of the upper limit or lower limit in the embodiments of the present invention, and the preferred range is the above-mentioned upper limit or lower limit value, and the following It may be a range defined by the value of the example or a combination of the values of the examples.

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

[Ethylene polymer]
Engage (registered trademark) ENR7256 manufactured by Dow Chemical Company
Ethylene/α-olefin copolymer density: 0.885 g/cm ³
MFR (190°C, 21.2N load): 2.5g/10 minutes

[Component (A): metal hydroxide]
A: Kisuma (registered trademark) 5P manufactured by Kyowa Chemical Co., Ltd.
Magnesium hydroxide average particle size: 1.0 μm

[Component (B): Silicone]
B: SH200 FLUID 12500 CS manufactured by Dow Corning Toray Co., Ltd.
Polydimethylsiloxane kinematic viscosity (25°C): 12500 cSt

<Component (C): Modified polyethylene having a density of 0.85 g/cm ³ or more and 0.90 g/cm ³ or less>
C: Modic (registered trademark) 730T manufactured by Mitsubishi Chemical Corporation
Maleic anhydride-modified polyethylene Density: 0.885 g/cm ³
MFR (190° C., 21.2 N load): 2.0 g/10 minutes Modification rate: 0.52% by mass

<Comparative modified polyethylene>
d1: Modic (registered trademark) M122 manufactured by Mitsubishi Chemical Corporation
Maleic anhydride-modified polyethylene Density: 0.920 g/cm ³
MFR (190° C., 21.2 N load): 1.3 g/10 minutes Modification rate: 0.28% by mass
d2: Modic (registered trademark) MMHDH1 manufactured by Mitsubishi Chemical Corporation
Maleic anhydride-modified polyethylene Density: 0.955 g/cm ³
MFR (190° C., 21.2 N load): 1.0 g/10 min Modification rate: 0.92% by mass

<Other ingredients>
Phenolic antioxidant: Irganox (registered trademark) IRGANOX1010 manufactured by BASF Japan

[Evaluation method]
Evaluation methods for the flame-retardant ethylene-based polymer compositions in the following examples and comparative examples are as follows.

<Oxygen Index>
Using the obtained pellets, a sheet with a thickness of 2 to 3 mm was formed with an open roll having a surface temperature of 130 ° C., and then a sheet with a thickness of 3 mm was formed by press molding (temperature: 190 ° C., pressure: 10 MPa) to obtain a press sheet. Ta. The oxygen index was measured according to JIS K7201 using this 3 mm thick press sheet.

<Tensile strength/tensile elongation>
The obtained pellets were extruded at 180° C. using a single screw extruder with a diameter of 20 mm to obtain an extruded tape with a width of 50 mm and a thickness of 1 mm. Using this extruded tape with a thickness of 1 mm, the tensile strength and tensile elongation were measured according to JIS K6723. A No. 3 dumbbell was used as the test piece, and the tensile speed was 200 mm/min.

[Example 1]
99 parts by mass of ethylene polymer, 100 parts by mass of component (A), 4 parts by mass of component (B), 1 part by mass of component (C), and 0.5 parts by mass of phenolic antioxidant are added to the content of 1.0 L. The mixture was inserted into a pressure kneader and kneaded at a set jacket temperature of 80°C of the pressure kneader. The resulting kneaded product was formed into a sheet by an open roll having a surface temperature of 120° C., and then pelletized by a pelletizer to obtain pellets of the flame-retardant ethylene polymer composition.

[Examples 2 to 7, Comparative Examples 1 to 3]
Pellets of a flame-retardant ethylene-based polymer composition were obtained in the same manner as in Example 1, except that the mixing ratio shown in Table-1 was used and 0.5 parts by mass of a phenolic antioxidant was added.

The pellets of the flame-retardant ethylene-based polymer compositions obtained in Examples 1 to 7 and Comparative Examples 1 to 3 were measured and evaluated for the oxygen index, tensile strength, and tensile elongation described above. The results are shown in Table-1.

[Evaluation results]
As shown in Table 1, the flame-retardant ethylene polymer compositions of Examples 1 to 7 have high oxygen indices and excellent flame retardancy.
From the results of Examples 1 to 7, it can be seen that the addition of component (C): modified polyethylene having a density of 0.85 g/cm ³ or more and 0.90 g/cm ^{3 or} less tends to greatly increase the oxygen index.

In Examples 1 to 7, 0.5% by mass, 1.5% by mass, 2.5% by mass, and 3.4% by mass of the component (C) in 100% by mass of the flame-retardant ethylene polymer composition , 4.9% by mass, 9.8% by mass, or 19.6% by mass. Regarding the oxygen index, it can be seen that even small amounts of component (C), such as 0.5% by mass, 1.5% by mass, and 2.5% by mass, are effective. In particular, in Example 1, which contains only 0.5% by mass, the oxygen index is greatly improved from 23 to 30 compared to Comparative Example 3, in which the component (C) is 0% by mass. . Also, the tensile strength is about the same, but the tensile elongation is improved from 807% to 858%.

On the other hand, in Comparative Examples 1 and 2, in which modified polyethylenes d1 and d2 having densities greater than 0.90 g/cm ³ were blended, the oxygen index was improved compared to Comparative Example 3, but the density was 0.885 g/cm ³ . It is not improved as much as Example 3 in which the same amount of modified polyethylene (C) was blended.
Therefore, it can be seen that the oxygen index is dramatically improved when the component (C): modified polyethylene having a density of 0.85 g/cm ³ or more and 0.90 g/cm ³ or less is blended.

INDUSTRIAL APPLICABILITY The flame-retardant ethylene polymer composition of the present invention can be used in a wide range of fields such as electric wires; electric wire coating materials; electric wire protective tubes; tubes; Since the flame-retardant ethylene-based polymer composition of the present invention is excellent in oxygen index and tensile properties, it is particularly suitable as a wire coating material among the materials listed above.

Claims (3)

A flame-retardant ethylene polymer composition containing the following components (A) to (C), wherein the content of component (C) in 100% by mass of the flame-retardant ethylene polymer composition is 0.1 to A flame-retardant ethylene-based polymer composition of 50% by mass.
Component (A): Metal hydroxide Component (B): Silicone component (C): Modified polyethylene having a density of 0.85 g/cm ³ or more and 0.90 g/cm ³ or less 2. The flame-retardant ethylene-based polymer composition according to claim 1, wherein the content of component (C) is 0.1 to 25% by mass based on 100% by mass of the flame-retardant ethylene-based polymer composition. A molded article using the flame-retardant ethylene polymer composition according to claim 1 or 2.