SE445559C - FLAME HAIR, HALOGEN-FREE POLYMER COMPOSITION AND APPLICATION THEREFORE FOR THE CREATION OF A HEAT PREPARABLE - Google Patents

Description

15 20 25 30 35 7909588-1 75 weight-96.

In most conditions it may be desirable to include in the polymeric composition a coupling agent to improve the compatibility of the flame retardant with the polymeric component or components of the composition, e.g. to improve the physical properties of the composition. Preferred coupling agents include organosilicon compounds and titanium derivatives such as silanes and titanates.

Examples of silanes which may be mentioned are dimethyl-idichlorosilane, methyltrichlorosilane, vinyltrichlorosilane, b-methacryloxypropyl-trimethoxysilane, N, N-bis (B-hydroxy-ethyl) -b * -amine-propyl-triethoxysilane, vinylpropyl-trimethoxysilane, X-methacryloxypropyl-trimethoxysilane, K-mercaptopropyl-trimethoxysilane, vinyltrimethoxysilane, X-glycidoxypropyltrimethoxysilane, β- (II-epoxy-cyclohexyD-ethyltrimethylsilane and vinyl-trimethoxyethoxylan) .

Examples of titanates and other organotanic derivatives useful as coupling agents are tetraisooctyl titanate, isopropyl diisostearyl methacrylate titanate, isopropyl triisostearoyl titanate, isopropyl triacrylate titanate, titanium diodioctylpyrophosphate) and especially so-called hybrid titanates such as isopropyl dimethacrylisostearoyl titanate. Additional suitable titanium compounds are described in 5.3.

Monte ö: G. Sugerman, Il. Year of Elastomers Plastics, Volume 8 (1976) p. 30-49, and in Bulletins KR 0326- !! and 0273-7, "Ken-React Titanate Coupling Agents for Filled Polymers" published by Kenrich Petrochem Inc.

When using coupling agent, the weight ratio between it and the flame retardant is preferably in the range 0.005 to 0.1: 1, in particular 0.01 to 0.005: 1.

The preferred inhibitors are those which release water on heating, especially hydrated aluminas of the formula Al 2 O 3 TXH 2 O, where x is in the range 0.5 to 3, especially Al 2 O 3 3.3H 2 O, ammonium or sodium dawsonite, hydrated magnesium oxide and hydrated calcium silicate, especially α-alumina trihydrates. Flame retardants such as alumina trihydrate preferably have a specific surface area of at least 0.1 m 2 / g, preferably at least 1 m 2 / g, e.g. 1 to 80 mZ / g, especially 3 to 20 mZ / g, measured according to Brunauer, Emmett and Teller's nitrogen absorption method (BET).

The particle size of the flame retardant is preferably less than 5 micrometers, especially less than 2 micrometers. Furthermore, or as an alternative, it may be advantageous to use a flame retardant which contains a mixture of different particle sizes, for example to reduce the melt viscosity of the composition. If desired, the flame retardant may be chemically treated to improve its compatibility with the polymeric material, with any of the above coupling agents, or, in the case of certain flame retardants such as alumina trihydrate, with processing aids such as stearic acid or stearates, e.g. calcium stearate.

The flame retardant is preferably used in an amount by weight of from 10 to 400 parts thereof per 100 parts of the polymeric component or components, especially from 50 to 200 parts per 100 parts of polymer component.

Remarkable results have been obtained using an amount of from 80 to 150 parts by weight of the flame retardant per 100 parts by weight of the polymeric component.

In addition to the inhibitor, the compositions of the present invention may comprise additional additives, for example fillers, stabilizers, such as UV stabilizers, antioxidants, acid acceptors and hydrolysis inhibitors, foaming agents and dyes, treatment aids such as plasticizers, or additional polymers. If additional additives are used, the compositions preferably contain less than 5% by weight of halogen in the composition as a whole, in particular less than 2% by weight of halogen, and in particular no halogen at all.

The polymeric compounds can be prepared in a conventional manner, for example by mixing the constituents of a Banbury mixer. They can then be processed into an envelope shape, for example by extrusion or casting, depending on the nature of the envelope material and the substrate, and crosslinked simultaneously or afterwards.

The polymeric compositions can be crosslinked, for example, by incorporating a crosslinking agent or by exposure to high energy radiation.

Suitable crosslinking agents are free radical initiators such as peroxides, for example dicumyl peroxide, 2,5-bislt-butylperoxy (ZJ-dimethylhexane and agx-bislt-butylperoxy) -disopropylbenzene. In a typical, chemically crosslinkable composition there is about 0.5 to 5% by weight of peroxide, based on the weight of the polymer blend. The crosslinking agent can be used separately or in combination with a co-curing agent such as a polyfunctional vinyl or allylic compound, e.g. triallyl cyanurate, triallyl isocyanurate or perltaerythritol tetramethacrylate.

Crosslinking by irradiation can be accomplished by exposure to high energy radiation such as an electron beam or y-rays. Radiation doses in the range 2 to 80 Zvlrad, preferably 2 to 50 Mrad, e.g. 2 to 20 Mrad and especially 11 to 12 l-lrad, are generally suitable. In order to promote crosslinking during irradiation, preferably from 0.2 to 5% by weight of a "prorad" such as a polyfunctional vinyl or allylic acid compound, for example triallyl cyanurate, triallyl isocylacetylate or peritzuzryl acrylonitrile netzryl acrylate, is introduced into the grain positioning composition. ,. ..._ - .., ....- .. -_ ...........__._.........- ..,. The degree of crosslinking of the compositions can be expressed as the gel content (ANSI / ASTM D2765-68) of the crosslinked polymeric composition, i.e. excluding any non-polymeric additives. The gel content of the crosslinked composition is preferably at least 10%, especially at least 20%, e.g. at least 30%, and in particular at least - '+ 0 °'.

The compositions of the invention can be used to form flame retardant coatings, e.g. for encapsulating elongate substrates, such as electrical insulation for a wire or cable. When it is desired to apply the coating as a sheath over the length of the substrate, it may be appropriate to extrude the composition directly onto the substrate prior to crosslinking, with simultaneous or subsequent crosslinking.

Alternatively - and especially when the coating is intended to enclose only a part of the substrate length - it may be appropriate to manufacture the coating before it is applied to the substrate, e.g. as a tape or sheet to be wrapped around the substrate or as a sleeve into which the substrate is to be inserted. When the coating is manufactured before it is applied to the substrate, it is suitable to manufacture it in dimension recoverable form, i.e. in such a form that its dimensional configuration can be substantially altered when subjected to appropriate treatment, especially in heat recoverable form, the dimensional configuration of which may be substantially altered when subjected to heat. The use of the compositions of the invention to form heat-recoverable articles constitutes a particular aspect of the present invention. The cladding can be made heat-recoverable by deforming its heat-stable configuration in cross-linked form at a suitable, elevated temperature, e.g. at a temperature above the crystalline melting point or softening point of the polymeric composition, with subsequent cooling when it has a deformed configuration. This can be done in a manner known per se, for example as described in US-PS 2,027,962, 3,086,242 and 3,957,372. For heat-shrinkable applications, it is preferred that the polymeric composition of the coating comprises a blend of the vinyl acetate / alkene copolymer with at least one thermoplastic polymer. The weight ratio of the vinyl acetate / alkene copolymer to the thermoplastic polymer may, for example, be in the range 1: 0.2 to 11, e.g. 1: 0.2 to 1.5, especially 1: 0.2 to 0.55. Preferred mixed thermoplastic polymers for heat recoverable applications are the thermoplastic polyalkenes and alkene / alkene copolymers described above.

In addition, and under certain conditions, it may be desirable to coat at least a portion of the surface of the liner which is in contact with the substrate with a sealant or adhesive, e.g. a hot melt, heat activatable, pressure sensitive or contact binder or a cement or putty, especially with a hot melt binder of the type described in DE-OS 2,723,116.

An application of the present invention which is of particular interest is electrical insulation, where the requirements for non-combustibility are extremely strict.

Examples of such applications are primary and secondary wire insulation, cable sheaths and wire and cable bundle wires, where the cladding is applied over the length of the substrate, and wire and cable splicing coverage and terminations in tape-q sheet or sleeve form, and cable and cable bundle branches in the form of tapes or shaped components, e.g. branch sleeves (often called joint sleeves), where the cladding is only applied to a part of the length of the wire, cable or bundle system.

A further application of the present invention, which is of particular interest, is sealing or mechanical or environmental protection of pipelines or ducts or at least parts thereof, e.g. joints or damaged inputs, e.g. in utility pipes such as gas or water pipes, heating pipes, ventilation and heating ducts, and pipes or pipes for domestic or industrial drains. An important example of such an application is in splicing air conditioning or ventilation ducts, where the cladding can be used in the form of a tape or a sheet, which is wrapped around the splice, or a sleeve, which encloses the splice, especially in heat-recoverable form.

In the above-mentioned uses, the coatings formed by the composition according to the invention are characterized by extremely low flammability and low emission of smoke and corrosive gas under strong ignition conditions. These properties have been found to be directly linkable to the overall level of vinyl acetate in the copolymer of the composition. In comparison with analogous compositions which do not have a polyalkene or alkene / alkene copolymer blend component and which have the same vinyl acetate content, coatings formed from compositions comprising a blend component of the polyalkene or alkene alkene have further been found to provide a significant improvement in chemical solvent inertness. especially oils, their flame retardant ability and often their smoke emission under strong ignition conditions.

The invention is illustrated in the following examples, where parts and percentages are by weight.

Examples 1 to 12 The actual grain positions are given in Table 1 below, which shows the proportions of the various components (approximated to the nearest integer).

The components were mixed uniformly on a two-roll laboratory mill heated to a temperature of 120 to 110 ° C, pressurized to plates at 190 ° C and then irradiated under atmospheric conditions with a 5.8 MeV electron beam at specified radiation doses. The samples were subjected to specified test methods.

Examples 13 to 18 The components listed in Table 1 below were mixed analogously to the previously described examples, cooling the two-roll laboratory grinder to prevent sticking. The plates produced were used for comparative purposes in the following tests. 7909588-1 N. w .. u.

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NN m .. ~ om .mm »nånn: nä: o fi w fi om fl wp fl cwn w fl Éëmcsumå. .Hon _. _. ._ wøpum w .. 2. o .. ou en om @ v. @ LßU = °. === «.«: w fi wšom fi øämcuw wm. Éëmcshmà m. MzÉ w. 2 w. N. .L Ü NM I o .. ... c .øaEvxm. ... mm / Fo 10 15 20 25 7909588-1 Test methods The plates manufactured according to the previous examples were subjected to the following tests: Water resistance, measured as 96 water uptake Oil resistance, measured as 96 oil uptake Tensile strength Elongation Flammability measured as limit oxygen index Smoke development ASTM-D-570-77, with the exception of the use of test plates of 25 mm diameter and 1.5 mm thickness ASTM-D-570-77, with the exception of the use of test plates of 25 mm diameter and 1.5 mm thickness BS 903 part A2 BS 903 part A2 ASTM-D-2863 measured in an Aminco NBS smoke chamber, according to Aminco-NBS smoke density chamber catalog Nr. 34-58005, 34- SSOOBE, instruction IMO, published November 1975 by American Instrument Co. 8030 Georgia Ave. Silver Spring, Maryland 20910, USA.

The test results are given in Table 2 below, and they clearly show e.g. the improved oil resistance of the blends (Examples 1 to 12) compared to the copolymer without polyethylene blend component (Examples 13 to 18), with the same ethylene and vinyl acetate content as the blend, as well as the improved lamination inhibition and in most cases lower smoke evolution. 7909588-1 0 0 0 .: 0.20 0 0.0 0.0 0 0.0 0; 0; 0 0: 0 2 0.0 00.052 ... 000.92 .. 0.5 0.00 0.8 0.00 0.00 0.0 ~ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0..0 ~ 0.00 0.3 0.: 0 0.0 ... moæï fi vsua0 0: 2 05 08 00 00 : _ 00: ~ 0f00 ~ 00 0: 0: E 00 0: 00 :. 02 0000000002. 0.0: 0 .: 0.0: 0 .: 0 .: 0.2 0.0 ä: 0 .: n: 0 .: 12 0.0: 0.0: 0 .: 0 .: 0 .: 0 .: 0.02ï..6 ... 0 = 0..0fl0 00 00 R 00 00 N .. 0.0 0.0 00 00 0 ... ä N: ä 3 00 2 0: 000 ~ .0.0.0 = 0.0¿ä0 00520 mrofæEm xwüvwfšw 00 00 ä . 00 00: 00 a R 2 2 00 S 0: 0 ~ - Nm ï 0: ïaw ... =. Z0 ~ ..z så ..

Uooo: E> wcmcwmpnanømo .ä 060.0 ~ .0: 0.: 0.0 0 .: 050 .: 050.20; 0.0: .0.0.0 150.0 0.0 10 f: 0 .: 0.0 0.200 0.0 0.0 0 .: 0.0 0.0 0.0 0.0 0.0: 0.0 ... ä 0.0 0.0 ~ .0 0.0 fa. Uoom v? wcwcwmpmmscou fl mf 8 0. 2 00 2 _: 2 2: 3 0 0 ... 0 0 ._ 0. N 0 ... ïäswxm N AAmm / É. 7 1595 2588 7909588-'1 Example 19 A heat-shrinkable tape was prepared from the following preparation: Component 96 x Sclair 11D 17 17 vinyl acetate / ethylene copolymer containing 33 60% vinyl acetate Al 2 O 3 -IZO coated with 1,596 vinyltriililane 50x Scylir the trade name of a linear low density ethylene / butene copolymer commercially available from Dupont.

The components were mixed on a twin roll mill at 120 to MOOC, cooled and pelletized. The pellets were fed to a conventional extruder equipped with a tape nozzle, kept at 110 ° C and extruded into 100 mm wide and 1.5 mm thick tape. The formed tape was then irradiated with high energy electrons to a total dose of 6 Mrad. After irradiation, the tape was heated to 150 ° C, expanded lengthwise to 50% of its original length and allowed to cool in the expanded state. Then the tape was coated with a thin layer (0.5 mm) of a hot melt binder with a composition according to DE-OS 2,723,116, Example 3, preparation "0". The tape had the following physical properties before coating: Tensile strength (ZBOC) 12.0 MPa clearance at break (23%) 266 see 1.01 (23%) 29 nfaghåiifasrher (1s0 ° c) 2.0 MPa clearance at man 100% range (150 °) c) 1.2 MPa The heat-shrinkable adhesive-coated tape thus produced was used to seal the joint on a 150 mm diameter air-conditioning pipe by preheating the pipe at the joint area, rearranging the tape around the pipe over the joint area with partial overlap of adjacent turns of the tape, and heating the tape with a conventional propane gas burner to cause the tape to shrink to fit snugly around the joint and cause the adhesive to melt and form a strong joint between the cladding thus formed and the conduit substrate.

In a modification, the pelleted material is extruded in the form of a sleeve, which is then made radially heat-recoverable and coated with a binder analogous to that described above. The sleeve thus manufactured is then placed around the pipe joint and recovered by heating.

Claims (10)

47 PATENT REQUIREMENTS 1. A flame retardant polymer composition, characterized in that it comprises a substantially crosslinked mixture of a vinyl acetate / alkene copolymer with a polyolefin or an alkene / alkene copolymer and comprises an effective amount of a halogen-free, inorganic flame retardant releasing water on heating, the mixture containing at least 0.2 parts by weight of polyalkene or alkene / alkene copolymer per part by weight of vinyl acetate / alkene copolymer and having a total vinyl acetate content of at least 18% by weight and the vinyl acetate copolymer having a vinyl acetate content greater than 45% by weight. 2. A composition according to claim 1, characterized in that the vinyl acetate / alkene copolymer is a vinyl acetate / ethylene copolymer. 3. A composition according to claim 1 or 2, characterized in that the halogenated inorganic flame retardant is alumina trihydrate. 4. A composition according to claim 1, 2 or 3, characterized in that the blend component is a polyethylene or an ethylene / C 1 -C 12 alkene copolymer. Composition according to Claim 1, characterized in that the blend component is an ethylene / Ca-Cl 2 -alkene copolymer having a density in the range 0.910 to 0.940 g / cma at ZSOC. Composition according to any one of Claims 1 to 5, characterized in that the weight ratio of vinyl acetate / alkene copolymer to the polyalkene or alkene / alkene copolymer in the mixture is in the range 1 to 0.2 to b. 7. A composition according to claim 6, characterized in that the weight ratio of vinyl acetate / alkene copolymer to alkene / alkene copolymer in the mixture is in the range 1: 0.2 to 1.5. Composition according to any one of claims 1 to 7, characterized in that the total amount of vinyl acetate in the mixture is at least 30% by weight. 46 Composition according to any one of Claims 1 to 8, characterized in that the polyolefin or the alkene / alkene copolymer is thermoplastic. Use of an fl-inhibited polymer composition comprising a substantially crosslinked blend of a vinyl acetate / alkene copolymer with a thermoplastic polyolefin or alkene / alkene copolymer and comprising an effective amount of a halogen-free inorganic lamination inhibitor which releases water on heating, wherein the mixture contains at least 0.2 parts by weight of the polyacene or alkene / alkene copolymer per part by weight of vinyl acetate / alkene copolymers and has a total vinyl acetate content of at least 18 weight-96 and the vinyl acetate copolymer has a vinyl acetate content greater than 05 weight-96, to form a heat-recoverable article.