JP2648870B2 - Flame retardant resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flame-retardant resin composition. More specifically,
For example, while having high flame retardancy that can pass the vertical flame retardancy test such as UL94V-0 or V-1, it is flexible and has excellent mechanical strength, electrical properties, heat resistance, and good extruded appearance. The present invention relates to the following flame-retardant resin composition.

(Prior Art) In recent years, in order to improve the safety of electric equipment, a technique for imparting high flame retardancy to a polyolefin resin having excellent electric properties has been advanced. For example, Japanese Patent Application Laid-Open No. 53-60944 discloses a highly advanced flame retardant obtained by using a mixture of a polyethylene polymer and a chlorine-containing flame retardant and a bromine-containing flame retardant in a specific ratio, and further combining antimony trioxide. A polyolefin composition having obtained flame retardancy is shown. JP-A-56-13
No. 6832 discloses a flame-retardant polyolefin composition obtained by combining a halogenated flame retardant, antimony trioxide and a specific amount of magnesium hydroxide with an ethylene-alkyl acrylate copolymer.

On the other hand, a flexible flame-retardant polyolefin resin, which facilitates wiring work, is also required for downsizing of equipment and high-density mounting of components. For example, JP-A-53-
No. 115081 discloses an ethylene propylene elastomer 10
0-50 parts by weight of ethylene vinyl acetate copolymer is blended so that the vinyl acetate group content is 0.1-10% by weight, and a flame retardant is further blended. A suitable composition for the wire is shown. JP-A-62-
No. 184042 discloses an ethylene-vinyl acetate copolymer or an ethylene-ethyl acrylate copolymer composed of an ethylene propylene diene-based copolymer, a specific antioxidant and a flame retardant, and having excellent flame resistance and heat resistance. 1 shows a hydrophilic resin composition.

(Problems to be Solved by the Invention) When a flame-retardant polyolefin composition is extruded and cross-linked onto a conductor to form a flame-retardant cross-linked polyolefin wire for wiring in equipment, flame retardancy, heat resistance as well as flexibility and appearance, A high balance between mechanical strength and electrical properties is required. However, within the range of the conventional technology, even a composition having excellent flame retardancy (JP-A-53-60944 or JP-A-56-1336832) is inferior in flexibility or, conversely, less flexible. Even an excellent composition (JP-A-53-115081 or JP-A-62-184042) is inferior in flame retardancy or a composition excellent in flame retardancy and flexibility (combining the above patents) However, even though the composition was poor, the balance of each property was poor, such as poor mechanical strength, and there was no satisfactory insulation layer or sheath for a polyolefin electric wire for wiring in equipment. In other words, within the scope of the prior art, the base polyolefin resin itself is insufficient and the flame retardant is also inadequate, so a better combination for the polyolefin resin and a more effective one for the flame retardant in a smaller amount. I had to find it.

(Means for Solving the Problems) In view of such circumstances, the present inventors have developed a material which is flexible, has excellent mechanical strength and electrical characteristics, has high flame retardancy, and provides good skin during extrusion molding. As a result of intensive studies on a well-balanced composition, the present invention has been achieved.

That is, the flame-retardant resin composition according to the present invention comprises an ethylene-vinyl acetate copolymer containing a vinyl acetate component of 7 to 25% by weight, and an ethylene-propylene-based elastomer of Mooney clay (ML _{1 +} 4,100 ° C.) 70 or less. 100 parts by weight of a polyolefin mixture, which is a main component and is mixed so that the vinyl acetate component in the mixture is 6 to 15% by weight, and 15 to 40 parts by weight of a halogen-based organic flame retardant, magnesium hydroxide
It is characterized by containing at least 10 to 60 parts by weight and at least 15 to 40 parts by weight of antimony trioxide and a zinc compound as a flame retardant aid.

The polyolefin mixture of the present invention mainly comprises an ethylene-vinyl acetate copolymer and an ethylene-propylene-based elastomer, and the vinyl acetate component in the mixture is at least 6% by weight.
% By weight or less.

If it is less than 6% by weight, it is difficult to obtain a high degree of flame retardancy with a small amount of flame retardant, and if it exceeds 15% by weight, the insulation resistance of the flame retardant composition of the present invention is lowered and the heat resistance is also lowered.

As the ethylene-vinyl acetate copolymer of the present invention, one containing a vinyl acetate component of 7% by weight or more and 25% by weight or less is used.

If it is less than 7% by weight, the flexibility and flame retardancy are insufficient, and if it exceeds 25% by weight, the insulation resistance is low and it is not suitable as an electrical insulating material. It is considered that the vinyl acetate component is greatly involved in the manifestation of the phenomenon for obtaining high flame retardancy such as incineration and carbonization in the action with the flame retardant of the present invention.

The ethylene propylene elastomer of the present invention may be an ethylene propylene binary copolymer or an ethylene propylene diene terpolymer. The Mooney clay (ML _{1 + 4} ,
(100 ° C.) is a relatively low Mooney viscosity of 70 or less, preferably 3 times or less and 0.6 times or more of the ethylene-vinyl acetate polymer. If the viscosity is more than 3 times, the appearance becomes particularly poor, and if the viscosity is less than 0.6 times, the mechanical strength is particularly lowered, which is not preferable.

Ethylene propylene based elastomers can impart flexibility and good electrical properties to the composition, but generally have an extruded appearance,
It deteriorates flame retardancy and mechanical strength. However, if the combination with the flame retardant of the present invention and the ethylene-vinyl acetate copolymer is used, and the above-mentioned specific viscosity is used, such a defect is not observed. In the polyolefin mixture of the present invention, in addition to the above two main components, polyethylene, polypropylene, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer are preferably used. It can be mixed within a range not exceeding 20% by weight, and the mixing ratio of the ethylene-vinyl acetate copolymer and the ethylene-propylene-based elastomer is naturally determined within a certain range by determining the vinyl acetate content in the ethylene-vinyl acetate copolymer. However, considering the effect of improving the flexibility of the ethylene propylene elastomer, preferably 10% of the entire polyolefin mixture
More than% by weight should be used.

As the halogen-based organic flame retardant of the present invention, those which are generally commercially available are used as they are, and chlorine-based organic flame retardants such as perchlor pentacyclodecane, dodecachlorooctahydrodimethanodibenzocyclooctene and dodecachlorooctahydrodimethanodibenzofuran are used. Flame retardants, bromine-based organic flame retardants such as decabromophenoxybenzene, tetradecabromo p-phenoxydiphenyl ether, and hexabromocyclododecane are used. Preferably, a bromine-based organic flame retardant that can obtain a high flame-retardant effect with a relatively small amount is used. Can be The amount used is 15 to 40 parts by weight based on 100 parts by weight of the polyolefin mixture. If the amount is less than 15 parts by weight, the flame retardancy is insufficient. If the amount exceeds 40 parts by weight, the mechanical strength is reduced, the blooming phenomenon and the like are not preferred, and the cost is increased.

As the magnesium hydroxide used in the present invention, a commercially available powdery magnesium hydroxide can be used as it is, and the amount to be used is 10 parts by weight or more and 60 parts by weight or less based on 100 parts by weight of the polyolefin mixture. If the amount is less than 10 parts by weight, the flame retardancy is not sufficient. If the amount exceeds 60 parts by weight, the mechanical strength is reduced, and the insulation resistance as an electrical insulator is undesirably reduced.

The magnesium hydroxide may be subjected to an appropriate surface treatment.

The flame retardant aid of the present invention is a metal oxide and / or a metal oxide mineral acid salt. As the metal oxide, an oxide of a metal such as zinc, antimony, bismuth, iron, and titanium is used, and zinc oxide and antimony trioxide are preferably used. As the metal oxide mineral salts, zinc borate, tribasic lead sulfate and the like are used, and zinc borate is preferably used. These flame retardant aids are used alone or in combination of two or more. Particularly preferred flame retardant aids are a combination of antimony trioxide and a zinc compound, specifically, a combination of antimony trioxide and zinc oxide, It is a combination of antimony oxide and zinc borate. As a preferable combination of the amounts used, 10 to 20 parts by weight of antimony trioxide and 5 to 30 parts by weight of zinc oxide and / or zinc borate are used with respect to 100 parts by weight of the polyolefin mixture.
It is a combination used below parts by weight. These may be used in an appropriate combination within the range of 15 to 40 parts by weight based on 100 parts by weight of the polyolefin mixture in the entire flame retardant aid. If the amount is less than 15 parts by weight, the flame retardant effect is not sufficient, and if it exceeds 40 parts by weight, the mechanical strength is reduced and the cost is increased.

The flame retardant comprising a combination of the halogenated organic flame retardant of the present invention, magnesium hydroxide and a flame retardant aid is used to improve mechanical strength, appearance, etc. with respect to 100 parts by weight of the polyolefin mixture. Is expensive, so it is preferable to use as little as possible in terms of cost,
Particularly preferably, it is 110 parts by weight or less.

The flame-retardant resin composition of the present invention includes known hindered phenol-based, sulfur-based, phosphorus-based, benzotriazole-based,
Known stabilizers such as amine-based, benzothiazole-based, benzimidazole-based, and hindered amine-based stabilizers can be added as necessary.

Magnesium silicate, aluminum silicate,
Fillers such as silicic acid anhydrides and metal carbonates can be blended as needed, and pigments and dyes can be blended as needed. In addition, a long-chain fatty acid metal salt, SEP rubber, silicone rubber, or the like may be mixed in order to improve the electrical insulation property or reduce the adhesiveness of the composition to metal. Further, in order to crosslink the composition of the present invention and use it as an electric insulator, a known radical generator, a polyfunctional ethylenically unsaturated monomer, and the like can be mixed.

(Examples) The characteristics of the materials used in the following examples are shown in Table 1. In general, the implementation was as follows. After putting the polyolefins of the number of parts shown in Table 2, Table 3, and Table 4 into the pressurized kneader of No. 2, the antioxidants of the number of parts shown in Table 2, Table 3, and Table 4 were added. Kneaded for 1 minute. Next, a filler and a flame retardant were charged and kneaded for 10 minutes.

The composition of the present invention can be obtained by the above-mentioned operation, but the following operation was further performed to evaluate the composition for a crosslinked polyolefin electric wire.

When evaluating by electron beam crosslinking, 3 parts by weight of triallyl isocyanurate was added to 100 parts by weight of the polyolefin mixture and further kneaded for 1 minute. In the case of evaluation by chemical crosslinking, 3 parts by weight of triallyl isocyanurate and 4 parts by weight of 2,5-dimethyl-2,5-di-t-butylperoxyhexyne were charged and kneaded for 1 minute.

After cross-linking the electron beam into a 0.8mm thick sheet, 20Mra
The chemical crosslinking was carried out by heating at 190 ° C. for 10 minutes. Tensile strength was evaluated at a speed of 500 mm / min at about 25 ° C., and heat resistance was indicated by residual elongation at break after thermal aging at 158 ° C. for 168 hours. The appearance was evaluated by coating the electric wires with each composition, and visually giving a score of 5,4,3,2,1 from those having good appearance. Flame retardancy was evaluated by a UL94 vertical flame retardant test method using a crosslinked sheet (0.8 mm thick). The varnish resistance test was carried out using an electric wire in which each composition was coated on a core wire of AWG # 20 to a thickness of 0.8 mm, and CSA C22.2 No.
The test was performed according to the test method specified in 116 CL1251.

The composition and each property of the examples and comparative examples are described in the same table,
All the amounts of the compounded chemicals are shown in parts by weight. In addition, each characteristic is based on the following test method.

-Tensile strength JIS C 3005-Elongation JIS C 3005-Tensile modulus ASTM D-638-Flame retardant UL 94-Volume resistivity JIS K 6911-Heat resistance JIS C 3005-Varnish resistance CSA C22.2 No.116 * The vinyl acetate content was measured according to JIS K 6730.

The evaluation results were almost the same for both the electron beam crosslinking and the chemical crosslinking except that the insulation resistance was reduced to about half in the case of the chemical crosslinking, and only the case of the chemical crosslinking was shown.

As can be seen from the examples, within the range of the present invention, tensile strength of 1.3 kg / mm ² or more, elongation of 350% or more, appearance of 4 or more, tensile modulus of 25 kg / mm ² or less, flame retardancy of 94V-0 Or 94V-1, volume specific resistance of 5 × 10 ¹⁴ Ω · cm or more and heat resistance of 85% or more. As for any of the above, one or more of the above is insufficient and cannot be balanced.

(Effects of the Invention) According to the present invention, a composition which is flexible, has excellent mechanical strength, flame retardancy, heat resistance, and exhibits a good extruded appearance can be obtained. This composition is UL94V even in vertical flame retardancy test at thickness of 1mm or less.
It shows flame retardancy equivalent to −0, and also shows sufficient mechanical strength and electrical insulation performance. After extruding this composition onto a copper wire,
Crosslinked polyolefin wires obtained by electron beam irradiation or by crosslinking with a radical generator show a good balance of good appearance, strength, flame retardancy and heat resistance. It is particularly preferable from the viewpoint of workability and assembling workability. As another effect, good results are obtained in a varnish resistance test as specified in CSA C22.2 No. 116 CL 1251.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication (C08K 13/02 3:22 3:10 5:02) (56) References JP-A-62- 225541 (JP, A) JP-A-62-184042 (JP, A) JP-A-61-183335 (JP, A)

Claims (1)

(57) [Claims] An ethylene-vinyl acetate copolymer containing a vinyl acetate component in an amount of 7 to 25% by weight and a Mooney viscosity (ML _{1 + 4} ,
(100 ℃) Mainly ethylene propylene elastomer of 70 or less, vinyl acetate component in the mixture is 6 to 15% by weight
Polyolefin mixture 10 mixed to be as follows
0 parts by weight, at least 15 to 40 parts by weight of a halogen-based organic flame retardant, 10 to 60 parts by weight of magnesium hydroxide, and at least 15 to 40 parts by weight of antimony trioxide and a zinc compound as a flame retardant aid. A flame-retardant resin composition comprising: