Flame-retardant resin composition

Abstract

To provide a resin composition which has excellent flame retardancy and is also excellent in fluidity and mechanical properties.SOLUTION: The resin composition contains (A) 20-30 wt.% of an ethylene-vinyl acetate copolymer (EVA) resin, (B) 1-10 wt.% of maleic anhydride-modified polyethylene, (C) 50-70 wt.% of magnesium hydroxide particles, (D) 1-5 wt.% of an acrylic-modified silicone resin, and (E) 1-10 wt.% of an ethylene / propylene-based thermoplastic elastomer (TPO resin).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a flame-retardant resin composition.

Background Art

[0002] Conventionally, as a flame-retardant resin composition used for forming an insulating layer of an insulated wire or cable, Patent Document 1 below discloses that (A) a linear ultra-low density polyethylene having a density of 0.880 to 0.908 g / cm 3 and a melt flow rate (MFR) of 0.5 to 4.0 g / 10 min at 190°C and a load of 2.16 kg is 30 to 60% by weight, (B) an ethylene-vinyl acetate copolymer (EVA) or ethylene-ethyl acetate copolymer (EEA) containing 12 to 25% by weight of a comonomer content and having a melt flow rate (MFR) of 0.1 to 5.0 g / 10 min at 190°C and a load of 2.16 kg is 40 to 70% by weight, and (C) as a flame retardant, 80 to 160 parts by weight of magnesium hydroxide is added to 100 parts by weight of the resin (A + B). A flame-retardant resin composition has been proposed.

[0003] Further, Patent Document 2 below discloses a composition containing an ethylene-based polymer (A), an acid-modified thermoplastic resin (B), polyethylene (C), and a flame retardant (D). The ethylene-based polymer (A) includes an ethylene-α-olefin polymer and an ethylene-unsaturated carboxylic acid ester copolymer. The acid-modified thermoplastic resin (B) is at least one thermoplastic resin selected from the group consisting of a maleic anhydride-modified thermoplastic resin and a maleic acid-modified thermoplastic resin. The polyethylene (C) has a density of 0.950 g / cm 3A flame-retardant resin composition has been proposed which has the above density, and in which the content of the ethylene-based polymer (A) in a total of 100% by mass of the ethylene-based polymer (A), the acid-modified thermoplastic resin (B), and the polyethylene (C) is 40% by mass or more and 85% by mass or less, the content of the acid-modified thermoplastic resin (B) is 10% by mass or more and 30% by mass or less, the content of the polyethylene (C) is 5% by mass or more and 30% by mass or less, and the flame retardant (D) is blended in a proportion of 80 parts by mass or more and 96 parts by mass or less with respect to 100 parts by mass of the total of the ethylene-based polymer (A), the acid-modified thermoplastic resin (B), and the polyethylene (C).

[0004] Further, Patent Document 3 below proposes a non-halogen flame-retardant resin composition containing, as a base polymer, either one of an ethylene-vinyl acetate copolymer and an ethylene-butene copolymer in an amount of 50 parts by mass or more and 90 parts by mass or less and low-density polyethylene in an amount of 10 parts by mass or more and 50 parts by mass or less, and containing 1 part by mass or more and 10 parts by mass or less of amorphous silica and 10 parts by mass or more and 150 parts by mass or less of a non-halogen flame retardant with respect to 100 parts by mass of the base polymer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the flame-retardant resin compositions described in Patent Documents 1 to 3 above, metal hydroxides such as magnesium hydroxide are contained in a high proportion as flame retardants. For this reason, these resin compositions have problems of being inferior in fluidity and mechanical properties. An object of the present invention is to provide a resin composition having excellent flame retardancy, fluidity, and mechanical properties.

Means for Solving the Problems

[0007] (1) The flame-retardant resin composition of the present invention is characterized by containing (A) 20 to 30% by weight of an olefin polymer, (B) 1 to 10% by weight of an acid-modified polyolefin, (C) 50 to 70% by weight of a flame retardant, (D) 1 to 5% by weight of a modified silicone, and (E) 1 to 10% by weight of an olefinic thermoplastic elastomer.

[0008] (2) In the flame-retardant resin composition of the present invention, the component (A) is composed of an ethylene (co)polymer and / or a propylene (co)polymer, the component (B) is composed of an acid-modified polyethylene and / or an acid-modified polypropylene, the component (C) is composed of an inorganic flame retardant, the component (D) is composed of a silicone modified by having an organic group compatible with polyethylene and polypropylene in a side chain, and the component (E) is preferably composed of an ethylene / propylene-based thermoplastic elastomer.

[0009] (3) In the flame-retardant resin composition of the present invention, it is more preferable that the component (A) is composed of an ethylene (co)polymer, the component (B) is composed of an acid-modified polyethylene, the component (C) is composed of a metal hydroxide, the component (D) is composed of a silicone modified by having an acrylic group or a vinyl acetate group in a side chain, and the component (E) is composed of the ethylene / propylene-based thermoplastic elastomer in which an ethylene propylene copolymer is dispersed in polypropylene.

[0010] (4) In the flame-retardant resin composition of the present invention, it is particularly preferable that the component (A) is composed of an ethylene vinyl acetate copolymer, the component (B) is composed of a maleic anhydride-modified polyethylene, the component (C) is composed of magnesium hydroxide or aluminum hydroxide, and the component (D) is composed of a silicone modified by having an acrylic group in a side chain.

Advantages of the Invention

[0011] The flame-retardant resin composition of the present invention has excellent flame retardancy and also excellent fluidity and mechanical properties.

Embodiments for Carrying Out the Invention

[0012] The flame-retardant resin composition of the present invention contains, as essential components, (A) an olefin polymer, (B) an acid-modified polyolefin, (C) a flame retardant, (D) a modified silicone, and (E) an olefin thermoplastic elastomer.

[0013] <(A) Olefin polymer> As the olefin polymer constituting the flame-retardant resin composition of the present invention as component (A), homopolymers of olefins such as polyethylene and polypropylene; ethylene vinyl ester copolymers, ethylene (meth)acrylic acid copolymers, ethylene (meth)acrylate copolymers, propylene vinyl ester copolymers, propylene (meth)acrylic acid copolymers, propylene (meth)acrylate copolymers, etc. can be mentioned, but it is not limited thereto. Among these, ethylene vinyl ester copolymers are preferred, and ethylene vinyl acetate (EVA) copolymers are particularly preferred. The content ratio of component (A) in the flame-retardant resin composition of the present invention is 20 to 30% by weight.

[0014] <(B) Acid-modified polyolefin> The acid-modified polyolefin constituting the flame-retardant resin composition of the present invention as component (B) is one in which at least one modified monomer selected from unsaturated organic acids and their derivatives is grafted onto a polyolefin. Examples of the polyolefin onto which the modified monomer is grafted include polyethylene or polypropylene.

[0015] Examples of the functional groups introduced by the modified monomer include functional groups having a C=O bond, such as a carbonyl group (>C=O), a carboxyl group (-COOH), an ester group, an acid anhydride, an amide group, and an imide group.

[0016] Preferred modified monomers include unsaturated dicarboxylic acids, unsaturated dicarboxylic anhydrides, and unsaturated dicarboxylic acid derivatives. Here, specific examples of the unsaturated dicarboxylic acid can include maleic acid, fumaric acid, and itaconic acid, etc.; specific examples of the unsaturated dicarboxylic anhydride can include maleic anhydride and itaconic anhydride, etc.; specific examples of the unsaturated dicarboxylic acid derivative can include monomethyl maleate, monoethyl maleate, diethyl maleate, monomethyl fumarate, dimethyl fumarate, diethyl fumarate, maleic monoamide, maleimide, N-phenyl maleimide, and N-cyclohexyl maleimide, etc. These can be used alone or in combination of two or more. Among these, maleic anhydride is preferred. Examples of the method for preparing the acid-modified polyolefin include a method in which a polyolefin, an antioxidant, a modified monomer, and an organic peroxide are mixed and heated in an extruder to cause a reaction, and then pelletized or granulated.

[0017] By containing the component (B) in a certain proportion or more, the resin composition of the present invention has good mechanical properties (high tensile strength and high elastic modulus). The content ratio of the component (B) in the flame-retardant resin composition of the present invention is 1 to 10% by weight. If the content ratio of the component (B) is too small, the resulting resin composition will not have good mechanical properties (see Comparative Example 3 described later). On the other hand, if the content ratio of the component (B) is too large, the fluidity of the resin composition will be impaired (see Comparative Example 4 described later), and the extrusion processability, etc. may decrease.

[0018] <(C) Flame retardant> As the component (C), the flame retardant constituting the flame-retardant resin composition of the present invention is preferably an inorganic flame retardant, and particularly preferably a metal hydroxide. When the metal hydroxide is heated, it decomposes and dehydrates, and the temperature of the resin composition can be lowered by this moisture, thereby suppressing its combustion. Examples of suitable metal hydroxides include magnesium hydroxide, aluminum hydroxide, and the like. It is preferable that the surface of the metal oxide constituting the flame retardant is surface-treated with a fatty acid, a silane coupling agent, or the like.

[0019] The content ratio of the component (C) in the flame-retardant resin composition of the present invention is 50 to 70% by weight. If the content ratio of the component (C) is too small, the resulting resin composition will not have good flame retardancy (see Comparative Example 5 described later). On the other hand, if the content ratio of the component (C) is too large, the fluidity of the resin composition will be impaired or the mechanical properties will be deteriorated (see Comparative Example 6 described later).

[0020] <(D) Modified silicone> As the modified silicone constituting the flame-retardant resin composition of the present invention as the component (D), silicone (polysiloxane) modified by having an organic group compatible with polyethylene and polypropylene in the side chain can be mentioned. Here, examples of the organic group in the side chain include an acrylic group and a vinyl acetate group. By containing such a modified silicone, the flame-retardant resin composition of the present invention can exhibit excellent fluidity due to silicone (polysiloxane structure) over a long period of time.

[0021] By containing the component (D) at a certain ratio or more, the resin composition of the present invention will have good fluidity (improvement of extrusion characteristics). The content ratio of the component (D) in the flame-retardant resin composition of the present invention is 1 to 5% by weight. If the content ratio of component (D) is too small, the resulting resin composition will not have good fluidity (see Comparative Example 7 described later). On the other hand, although the resin composition with an excessive content ratio of component (D) has good fluidity and mechanical properties (see Comparative Example 8 described later), component (D) precipitates (bleeds out) on the surface of the resin composition, causing appearance defects such as cloudiness on the surface of the final product, which is not preferable.

[0022] <(E) Olefinic thermoplastic elastomer> The olefinic thermoplastic elastomer constituting the flame-retardant resin composition of the present invention as component (E) is an elastomer showing thermoplasticity, containing a hard segment made of polyolefin and a soft segment made of aliphatic rubber.

[0023] Here, examples of the hard segment (polyolefin) include polypropylene or polyethylene, and it is preferable to use polypropylene. Examples of the soft segment (aliphatic rubber) include ethylene-propylene copolymer (EPM) and ethylene-propylene-diene copolymer (EPDM). By using polyethylene or polypropylene as the hard segment and EPM or EPDM as the soft segment, an ethylene / propylene-based thermoplastic elastomer can be constituted.

[0024] Examples of the method for producing an olefinic thermoplastic elastomer include a method of mechanically blending a polyolefin and an aliphatic rubber, and a method of polymerizing an olefin in the presence of an aliphatic rubber. By the latter method, an olefinic thermoplastic elastomer (ethylene / propylene-based thermoplastic elastomer) in which an aliphatic rubber (EPM or EPDM) is finely dispersed in a polyolefin (polypropylene or polyethylene) can be produced.

[0025] By containing an olefin-based thermoplastic elastomer, the flame-retardant resin composition of the present invention has excellent mechanical properties (high elastic modulus).

[0026] The content ratio of the component (E) in the flame-retardant resin composition of the present invention is 1 to 10% by weight. If the content ratio of the component (E) is too small, the resulting resin composition will not have good mechanical properties (high elastic modulus) (see Comparative Example 1 described later). On the other hand, if the content ratio of the component (E) is too large, the tensile strength of the resulting resin composition will decrease (see Comparative Example 2 described later).

[0027] <Optional component> In addition to the above components (A) to (E), the flame-retardant resin composition of the present invention may contain stabilizers (light stabilizers, antioxidants, processing stabilizers), various additives (processing improvers, dispersants, copper poisoning inhibitors, antistatic agents, lubricants, fillers), etc., as long as the properties of the resin composition of the present invention are not impaired.

[0028] <Method for producing resin composition> The flame-retardant resin composition of the present invention can be produced by blending the essential components [(A) component to (E) component] and optional components in a predetermined ratio and melt-kneading them.

[0029] <Use of resin composition> The flame-retardant resin composition of the present invention can be suitably used as an insulating coating material for various electric wires and cables.

Examples

[0030] Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples. Here, the (A) olefin-based polymer, (B) acid-modified polyolefin, (C) flame retardant, (D) modified silicone, (E) olefin-based thermoplastic elastomer, and optional components used to produce the resin compositions of the examples and comparative examples are as follows.

[0031] (A1) Olefin-based polymer: · Ethylene vinyl acetate copolymer (EVA) resin [density = 0.95 g / cm 3 , vinyl acetate content = 25 wt%, MFR (2.16 kg) = 5.0 g / 10 min]

[0032] (B1) Acid-modified polyethylene: · Maleic anhydride-modified polyethylene [density = 0.94 g / cm 3 , maleic anhydride content = 0.4 wt%, MFR (2.16 kg) = 1.8 g / 10 min]

[0033] (C1) Flame retardant: · Magnesium hydroxide particles with an average particle diameter of 1.1 μm surface-treated with fatty acid

[0034] (D1) Modified silicone: · Acrylic silicone resin obtained by graft polymerizing an acrylic group onto the main chain silicone (silicone content 70 wt%)

[0035] (E1) Olefin-based thermoplastic elastomer: · Ethylene / propylene-based thermoplastic elastomer [TPO resin, density = 0.88 g / cm 3 , MFR (2.16 kg) = 0.25 g / 10 min]

[0036] (F1) Optional component: · Carbon black-containing masterbatch

[0037] <Examples 1 to 9 and Comparative Examples 1 to 8> According to the formulations shown in Table 1 below, each component was melt-kneaded to obtain the resin composition of the present invention and the resin composition for comparison.

[0038] <Evaluation> For each of the resin compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 8 above, the following evaluation tests were conducted. The measurement method, evaluation method, and evaluation criteria are as follows. The results are also shown in Table 1.

[0039] (1) Using a flame-retardant heating press machine (manufactured by Toho Machinery, model TBD-50), the resin composition was pressed at 180 °C for 2 minutes to form a sheet with a thickness of 3 mm. Test specimens (specimen shape IV described in Table 2 of JIS K 7201) were prepared from the obtained sheet-shaped molded body, and the oxygen index (LOI) was measured in accordance with JIS K 7201 except for using this test specimen. Those with an oxygen index (LOI) exceeding 35 were evaluated as "qualified", and those with 35 or less were evaluated as "unqualified".

[0040] (2) Fluidity The melt mass flow rate (MFR) was measured in accordance with JIS K 7210. Here, the measurement temperature was 200 °C and the load was 211.68 N (21.6 kg). Those for which the MFR could be measured were evaluated as "qualified", and those with an excessively low MFR that could not be measured were evaluated as "unqualified".

[0041] (3) Mechanical properties (tensile test) Using a heating press machine (manufactured by Toho Machinery, model TBD-50), the resin composition was pressed at 180 °C for 2 minutes to form a sheet with a thickness of 1 mm. A No. 3 dumbbell test specimen was prepared from the obtained sheet-shaped molded body. Using this test specimen, a tensile test was conducted at a tensile speed of 200 mm / min using a tensile testing machine (Autograph AGS-X manufactured by Shimadzu Corporation), and the tensile strength and elongation at break were measured. Those with a tensile strength of 10 MPa or more were evaluated as "qualified", and those with less than 10 MPa were evaluated as "unqualified".

[0042] (4) Mechanical properties (elastic modulus) Using a rheometer (MCR302 manufactured by Anton Paar), the change in complex viscosity of the resin composition was measured under the conditions of a temperature of 70 °C, a frequency of 10 Hz, and a strain of 0.5%, and the storage elastic modulus was calculated. Those with an elastic modulus (at 70 °C) of 20 MPa or more were evaluated as "qualified", and those with less than 20 MPa were evaluated as "unqualified".

[0043]

Table 1

Claims

1. (A) 20 to 30% by weight of an olefin polymer, (B) 1 to 10% by weight of an acid-modified polyolefin, (C) 50 to 70% by weight of a flame retardant, (D) 1 to 5% by weight of a modified silicone and (E) 1 to 10% by weight of an olefinic thermoplastic elastomer A flame-retardant resin composition containing the same.

2. The component (A) is composed of an ethylene (co)polymer and / or a propylene (co)polymer, The component (B) is composed of an acid-modified polyethylene and / or an acid-modified polypropylene, The component (C) is composed of an inorganic flame retardant, The component (D) is composed of a silicone modified by having an organic group compatible with polyethylene and polypropylene in the side chain, The flame-retardant resin composition according to Claim 1, wherein the component (E) is composed of an ethylene / propylene-based thermoplastic elastomer.

3. The component (A) is composed of an ethylene (co)polymer, The component (B) is composed of an acid-modified polyethylene, The component (C) is composed of a metal hydroxide, The component (D) is composed of a silicone modified by having an acrylic group or a vinyl acetate group in the side chain, The flame-retardant resin composition according to Claim 2, wherein the component (E) is composed of the ethylene / propylene-based thermoplastic elastomer in which an ethylene-propylene copolymer is dispersed in polypropylene.

4. The component (A) is composed of an ethylene-vinyl acetate copolymer, and the component (B) is composed of maleic anhydride-modified polyethylene, The component (C) is composed of magnesium hydroxide or aluminum hydroxide, The flame-retardant resin composition according to Claim 3, wherein the component (D) is composed of a silicone modified by having an acrylic group in the side chain.

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