JPS63125547A - Crosslinkable flame-retarding composition - Google Patents

Abstract

PURPOSE:To obtain a crosslinkable flame-retarding composition excellent in receptivity of filler, mechanical strength, heat resistance, etc., high in crosslinkability and suitable as, e.g., an electrical insulation material, by mixing an ethylene copolymer of a specified composition with a flame retardant at a specified weight ratio. CONSTITUTION:An ethylene copolymer comprising ethylene, 0.005-2mol% vinyl (meth)acrylate or allyl (meth)acrylate and 2.5-20mol% unsaturated carboxylic acid (ester) (e.g., ethyl acrylate) or vinyl ester (e.g., vinyl acetate) is prepared. 100pts.wt. this ethylene copolymer is mixed with 10-200pts.wt. flame retardant to obtain the purpose crosslinkable flame-retarding composition. As said flame retardant, a combination of an inorganic flame retardant such as magnesium hydroxide or aluminum hydroxide with a halogenated flame retardant such as hexabromobenzene or tetrabromoethane is desirable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a crosslinkable flame retardant composition having excellent mechanical strength and heat resistance.

(Prior art) Because polyolefins have excellent physical and chemical properties, they can be molded into films, cants, pipes, containers, etc. using various molding methods such as extrusion molding, injection molding, and rotary molding, and are used for household, It is a general-purpose resin with the highest demand for use in many industrial applications.

Since the above-mentioned polyolefin is easily flammable, various methods have been proposed to make it flame retardant.

The most common method is to add a flame retardant containing halogen or phosphorus to the polyolefin to make it flame retardant. The degree of flame retardation increases with the amount of flame retardant added. However, an increase in the amount added not only causes a decrease in mechanical strength, workability, etc., but also has the drawback of significantly impairing flexibility, cold resistance, etc. Further, these conventional flame retardant compositions are required to be highly flame retardant from the standpoint of disaster prevention, and there is a tendency for such compositions to be required depending on the application. From this perspective, inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide meet these needs and are rapidly increasing in demand as low-smoke, non-polluting flame retardants that do not generate harmful gases during combustion. (For example, such techniques are disclosed in Japanese Patent Application Laid-open Nos. 51-132254 and 51-132254,
6-136832, 60-13832, etc.)
.

On the other hand, as an electrical insulating material, for example, resins for electrical cables are required to have excellent crosslinking properties as one of the important properties.

However, for example, in conventional polyethylene for power cables, unless a large amount of crosslinking agent is added, the gel fraction does not improve, and the heat deformation rate at high temperatures above the melting point increases significantly, making it more heat resistant. There is a strong need for sexual improvement.

In addition, conventionally commercially available polyethylene has
Poor receptivity to inorganic flame retardants and low flame retardant effect. Also,
If the filling amount is increased, the mechanical strength, flexibility, workability, etc. decrease, and this has the disadvantage that it cannot be put to practical use.

(Problems to be Solved by the Invention) The purpose of the present invention is to solve the problems of the above-mentioned prior art,
Particularly, the object of the present invention is to provide a crosslinkable flame retardant composition that has good receptivity to fillers, can be used to obtain a high degree of flame retardancy, is rich in crosslinkability, and has improved heat resistance. Another object of the present invention is to provide a composition that exhibits remarkable effects as an electrically insulating material.

(Means for Solving the Problems) The present invention comprises (a) substantially ethylene and (bl (meth)vinyl acrylate or (meth)acrylate ali)
, 0.005 to 20 mol% and (c) unsaturated carboxylic acid or its ester or vinyl ester2.
It is a crosslinkable flame retardant composition containing 10 to 200 parts by weight of a d1 flame retardant to 100 parts by weight of an ethylene copolymer consisting of 5 to 20 mol%.

The above (al component, substantially ethylene) may include other a-olefins in addition to ethylene,
The α-olefins include propylene, butene-1,
Pentene 1, hexene-1,4-methyl-pentene-1
, octene-1, decene-1, etc., and mixtures thereof.

Component (b) in the above copolymer is vinyl methacrylate, vinyl acrylate, allyl methacrylate, and allyl acrylate, and the content thereof is o, oos to 2.0.
A mole %, preferably 0.01 to 1 mole %, is suitable.

When the above monomer is less than o, oos mol%, there is almost no effect of modifying the crosslinking property of the ethylene copolymer, and 20
If it exceeds mol%, it becomes economically expensive and also gelation occurs during polymerization or molding, making molding difficult or resulting in poor appearance.

The unsaturated carboxylic acid or its ester which is the component (c) in the above copolymer includes methacrylic acid, acrylic acid, ethyl methacrylate, glycidyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, and acrylic acid. phenyl, maleic acid, fumaric acid,
Examples include unsaturated carboxylic acids such as crotonic acid, icconic acid, and citraconic acid, or esters thereof.

As mentioned above (as the vinyl ester which is the c1 component), vinyl esters of saturated aliphatic carboxylic acids such as vinyl formate, vinyl acetate, and vinyl butyrate can be exemplified.

The content of the unsaturated carboxylic acid or its ester or vinyl ester, which is the component (c), is 25 to 20 mol%, preferably 3 to 15 mol%, and if the content is less than 25 mol%, magnesium hydroxide etc. It has poor receptivity to inorganic flame retardants and becomes brittle, resulting in a decrease in mechanical strength and flame retardancy. Further, even when the content is 20 mol %, the strength of the resin is still low and the mechanical strength is reduced.

Among the above tc+ components, ethyl acrylate is particularly preferred in terms of electrical properties and the like.

The ethylene copolymer of the present invention is preferably produced by a conventional high-pressure radical polymerization method.

The above-mentioned high-pressure radical polymerization method refers to a polymerization pressure of 500 to 400
0 kg/ci, preferably 1000-3500 kg
/ crd 1 under conditions of reaction temperature 50-400°C, preferably 100-350°C, in the presence of a free radical catalyst and a chain transfer agent, if necessary auxiliaries, in a seed or back type reactor with ethylene. A method in which monomers are contacted and polymerized simultaneously or in stages.

The free radical catalysts include hydrogen, propylene, butene-1.
, CS-C or higher saturated aliphatic hydrocarbons and halogen-displaceable hydrocarbons, such as methane, ethane, propane, isobutane, n-hexane, n-hebutane, cycloparaffin 9, aroform and carbon tetrachloride. , 01~
Saturated aliphatic alcohols of C2o or more and isopropano-k, C, -C2o or more saturated aliphatic carbonyl compounds, such as carbon dioxide, acetone and methyl ethyl ketone and aromatic compounds such as toluene, ethylbenzene and xylene. Examples include compounds such as

As the flame retardant which is component (d) of the present invention, additive flame retardants such as halogen flame retardants, phosphorus flame retardants, and inorganic flame retardants may be used. The above halogenated flame retardants include tetrabromobisphenol A (TB), hexabromobenzene, decabromodiphenyl ether, tetrabromoethane (THE), and tetrabromobutane (TBB).
, hexabromocyclodecane (HBCD) and chlorinated paraffins, chlorinated polyphenyl, chlorinated polyethylene, chlorinated diphenyl, perchloropentacyclodecane, chlorinated naphthalene, etc.; It is more effective when used together.

In addition, phosphorus-based flame retardants include tricresyl phosphate, tri (β-chloroethyl) phosphate-I, tri (dichloropropyl) phosphate, tri (dibromopropyl) phosphate, 2,3-dibromopropyl-2,3- Main examples include phosphoric esters such as chloropropyl phosphate and halogenated phosphoric esters.

Furthermore, the inorganic flame retardants of the present invention include aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, basic magnesium carbonate, dolomite, hydrotalcite, calcium hydroxide, barium hydroxide, tin oxide hydrate,
Hydrates of inorganic metal compounds such as borax, zinc borate, zinc metaborate, barium metaborate, zinc carbonate, magnesium calcium carbonate, calcium carbonate, barium carbonate, magnesium oxide, molybdenum oxide, zirconium oxide,
Examples include tin oxide, antimony oxide, and red phosphorus. These may be used alone or in combination of two or more. Among these, at least one selected from magnesium hydroxide and aluminum hydroxide has a good flame retardant effect and is economically advantageous.

In addition, the particle size of these flame retardants varies depending on the type, but for magnesium hydroxide, aluminum hydroxide, etc.
The average particle diameter is preferably 20 μm or less, more preferably 5 μm or less.

The amount of the flame retardant is 10 to 20 parts by weight per 100 parts by weight of the resin.
0 parts by weight, preferably in the range of 20 to 150 parts by weight. Especially when using only the above-mentioned inorganic flame retardant,
It is preferable to use it in a range of 0 to 200 parts by weight. If the amount of the flame retardant is less than 10 parts by weight, the flame retardant effect will be small, and if it exceeds 200 parts by weight, the mechanical strength and elongation will decrease, flexibility will be lost, the product will become brittle, and the low-temperature properties will also deteriorate.

In the composition of the present invention, at least one of the above additive flame retardants is used, and as mentioned above, magnesium hydroxide, aluminum hydroxide, etc. are particularly preferred, and they may also be used in combination with a halogen flame retardant. is also preferable.

Furthermore, in the present invention, by using an inorganic filler and a flame retardant in combination, the amount of flame retardant added can be reduced, and other properties can also be imparted.

Inorganic fillers as optional ingredients used in the present invention include calcium sulfate, calcium silicate, clay, diatomaceous earth, talc, alumina, silica sand, glass powder, iron oxide, metal powder, graphite, silicon carbide, silicon nitride, silica, Powder-like fillers such as boron nitride, aluminum nitride, and carbon black, mica, glass plates, metal foils such as sericite, pyrolite, and aluminum flakes, flattened plate or scale-like fillers such as graphite, white glass balloons, and metals. balloon,
Examples include glass balloons, hollow fillers such as pumice, glass fibers, carbon fibers, graphite m-fibers, whiskers, gold a-fibers, silicon carbide fibers, and mineral fibers such as asbestos and wollastonite.

The amount of these additives to be added is approximately 100 parts by weight per 100 parts by weight of the composition of the present invention.

If the amount added exceeds 100 parts by weight, the mechanical strength such as impact strength of the molded article will decrease, which is not preferable.

Examples of methods for crosslinking the composition of the present invention include crosslinking with organic peroxides, silane crosslinking, and irradiation crosslinking such as electron beam irradiation. Examples of commonly used organic peroxides include dicumyl peroxide, tert- Butyl dicumyl peroxide, 2,5-dimethyl-2,5-di(tert)
-butylperoxy)hexane, 2゜5-dimethyl-2
,5-di(tert-butylberoxine)hexyne-
3, etc., and 100 weights of the composition of the present invention.

Usually 0.1 to 5 parts by weight, preferably 0.4 to 5 parts by weight
2 parts by weight. In silane crosslinking, vinyl alkoxysilane (such as vinyltrimethoxysilane) is grafted onto the composition and then water crosslinked. Furthermore, for irradiation crosslinking, high-energy electron beam, x! An irradiation source such as s is employed as appropriate.

Among the above-mentioned crosslinking methods, crosslinking using an organic peroxide is particularly preferred.

The composition of the present invention comprises (al substantially ethylene; (b)
an ethylene copolymer consisting of vinyl (meth)acrylate or allyl (meth)acrylate, (c) an unsaturated carboxylic acid or its ester or vinyl ester, and (d
) Flame retardants, inorganic fillers, additives, etc., if desired, are added using a Banbury mixer-1 pressurized Nigoo, kneading extruder, twin-screw extruder,
Usually, it is melt-kneaded using a commonly used mixer such as a roll, turned into pellets, etc., and then provided as a molded product or a masterbatch. Good too.

The composition of the present invention also includes other synthetic resins, antioxidants, lubricants, various organic and inorganic pigments, ultraviolet inhibitors, dispersants,
Additives such as copper damage inhibitors, neutralizing agents, blowing agents, plasticizers, antifoaming agents, flow improvers, nucleating agents, and the like may be added to the extent that they do not significantly impair the effects of the present invention.

(Operations and Effects of the Invention) As described above, the crosslinkable flame retardant composition of the present invention contains [substantially ethylene as the al component and (meta) as the component (b).
A composition in which a flame retardant as a dl component is added to an ethylene copolymer consisting of vinyl acrylate or allyl (meth)acrylate and an unsaturated carboxylic acid or its ester or vinyl ester as a cl component; has good receptivity to fillers, can achieve a high degree of flame retardancy, is rich in crosslinking properties, and can significantly improve mechanical strength and heat resistance.Inorganic flame retardants,
For example, by using aluminum hydroxide, magnesium hydroxide, etc., a flame-retardant composition that does not generate harmful gases during combustion, has low smoke properties, and is non-polluting is required to be highly flame-retardant. This will meet the current needs of the world.

In addition, the composition of the present invention, especially the composition consisting of an ethylene copolymer using ethyl acrylate as a comonomer of the Cl component, has excellent electrical properties, so it can be used for electric wires,
It can be used as an electrical insulating material for cables, etc., and as an electrical material for jacket materials, etc. In particular, cables for various power generation plants, including nuclear power research institutes, which specify the amount of corrosive gas,
Suitable for use in locations that require a high degree of flame retardancy, such as chemical, steel, and petroleum plant cables, fire-resistant electric wires, and general household wiring.

It is also used for molding applications such as extrusion molded products such as films, sheets, and pipes, or injection molded products, and as masterbatches, and is used in various fields such as textiles, electricity, electronics, automobiles, ships, aircraft, architecture, and civil engineering. It can be used as panels, packaging materials, furniture, household goods, etc.

(Example) Production method of ethylene copolymer A predetermined amount of ethylene was placed in a metal autoclave equipped with a stirrer that had been sufficiently purged with nitrogen and ethylene, and the following (b) and (c
1 component and n-hexane as a chain transfer agent,
Furthermore, a polymerization initiator, di-tarjarybutyl peroxide, was injected and polymerization was carried out under the conditions of a pressure of 1600 kg/crd, a polymerization temperature of 170°C, and a polymerization time of 60 minutes. A polymer was produced.

(bl component allyl methacrylate (AMA) vinyl methacrylate (VMA) allyl acrylate (AAI) (c) component ethyl acrylate (EA) vinyl acetate (VA) Examples 1 to 8 The following ethylene copolymer was added to the above ethylene copolymer. (d) Flame retardant and dicumyl peroxide (product name: Percumil 02 NOF-
(manufactured by Ohmukai Shinko Co., Ltd.) 2 wt%, 4.4'-thiobis-(6-tert-butyl-4-methylphenol) (hereinafter referred to as Thiobis) (trade name: Nicklac 300, manufactured by Ohmukai Shinko Co., Ltd.) 0.2 + vt%. Table 1 shows the results of measuring the tensile strength, elongation, heat resistance (heat deformation rate), gel fraction, oxygen index, specific volume resistivity, etc. of the composition that was blended with the following ingredients and kneaded with a roll at a temperature of 120°C. It was shown to.

(However, the gel fraction was measured without adding flame retardant).

(dl II Fuel Low Density Polyethylene (Product Name: Nisseki Shixuron W2O0
Table 1 shows the results of evaluation in the same manner as in Example 1 using ethylene-ethyl acrylate copolymer (EA content 47, A content 57). (Comparative Examples 1 to 3) In addition, ethylene-AMA-EA ternary copolymers outside the scope of the present invention were produced and evaluated in the same manner as in Example 1. The results are shown in Table 1. Examples 4 to 6) The test method is as follows.

Test method> A test piece was prepared by punching out a No. 3 dumbbell from a sheet with an elongation thickness of 1 am/a and a tensile speed of 200 mm.
Measured at a speed of Z minutes.

2 Heating deformation rate It was conducted in accordance with JIS C 3005. Temperature 120℃
, measured under a load of 1 kg.

shi 2nd public circle Dicumyl peroxide (trade name: Percyl D.

2.0 wt% (manufactured by NOF Corporation), 0.2 wt% of Thiobis (trade name: Nicklac 300, manufactured by Ohmukai Shinko ■ Co., Ltd.) and the ethylene copolymer were kneaded with a roll at 120°C.
Samples heat-crosslinked for 30 minutes in a press molding machine at 0℃
Grind to within 20 mesh and heat at 120°C for 10
The remaining rate without time extraction was determined.

4 oxygen index It was conducted in accordance with JIS K 7201.

i Sub 1115” U Tomoshima It was conducted in accordance with JIS K 6723.

Claims (1)

[Scope of Claims] 1) (a) substantially ethylene; (b) vinyl (meth)acrylate or allyl (meth)acrylate; 0.00
With respect to 100 parts by weight of an ethylene copolymer consisting of 5 to 2.0 mol% and (c) 2.5 to 20 mol% of an unsaturated carboxylic acid or its ester or vinyl ester,
(d) A crosslinkable flame retardant composition containing 10 to 200 parts by weight of a flame retardant. 2) The crosslinkable flame retardant composition according to claim 1, wherein the unsaturated carboxylic acid or its ester or vinyl ester (c) is ethyl acrylate or vinyl acetate. 3) Claim 1, wherein the flame retardant is an inorganic flame retardant.
The crosslinkable flame retardant composition according to item 1 or 2. 4) The crosslinkable flame retardant composition according to claim 3, wherein the inorganic flame retardant comprises magnesium hydroxide, aluminum hydroxide, or a mixture thereof. 5) The crosslinkable flame retardant composition according to any one of claims 1 to 4, characterized in that a halogenated flame retardant and an inorganic flame retardant are used together as flame retardants. 6) Claims 1 to 6, wherein the ethylene copolymer is an ethylene copolymer obtained by a radical polymerization method.
The crosslinkable flame retardant composition according to any one of Item 5.