AU694394B2

AU694394B2 - Stabilizer composition for cable sheathings

Info

Publication number: AU694394B2
Application number: AU42720/97A
Authority: AU
Inventors: Stefan Forster; Walter Reith; Michael Rosenthal
Original assignee: Baerlocher GmbH
Current assignee: Baerlocher GmbH
Priority date: 1996-10-23
Filing date: 1997-10-20
Publication date: 1998-07-16
Anticipated expiration: 2017-10-20
Also published as: EP0838493A1; EP0838493B1; DE59704232D1; CA2218792C; DK0838493T3; DE19644128A1; DE19644128C2; CA2218792A1; AU4272097A; ATE204008T1; TW334460B; BR9705114A; ZA979292B; ES2163699T3; AR004446A1; GR3037051T3; JPH11162257A

Description

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AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): BAERLOCHER GMBH Invention Title: STABILIZER COMPOSITION FOR CABLE SHEATHINGS The following statement is a full description of this invention, including the best method of performing it known to me/us: -1CI-Y- Y I _I_ Stabilizer Composition for Cable Sheathings The present invention relates to the use of molding compositions which are based on \i halogen-containing polymers, particularly polyvinyl chloride, and contain a stabilizer composition, namely in the produ:;tion of cables in order to prevent any drop in the electrical resistance value caused by the long-term action of moisture.

At the moment, stabilizers based on basic lead compounds, such as tribasic lead sulfate, dibasic lead stearate or dibasic lead phthalate, are normally used for the thermoplastic processing of polyvinyl chloride to prevent polymer from decomposing during processing. Such stabilizers which contain heavy met.is are preferably used together with further organic and inorganic co-stabilizers in applications where high long-term demands are made on heat and weather stability. In addition, when cable sheathings are stabilized, the electrical values required by various standards must be i observed. A high electrical resistance is very important for preventing short-circuiting.

Particularly critical are here the long-term electrical-resistance characteristics under j ithe action of moisture, which is, for instance, the case with outdoor applications. The lead staoilizers which are presently used meet all of the demands made on them.

1 iSince lead compounds are classified as toxic, attempts have been made since quite Isome time to find a substitute therefor. Stabilizers which are free from heavy metals, S.1 'above all stabilizers based on calcium and zinc compounds, so-called calcium-zinc r. stabilizers, have been used for The stabilization of cables since some time, but these stabilizers exhibit an electrical resistance that is considerably inferior to that of standard lead stabilizers with respect to long-term stability.

FR-A-24 03 326, for instance, describes the stabilization of plasticized polyvinyl chloride for cable insulations with a mixture of fatty acids of calcium and zinc, of c i 1 11--4

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2 sorbite and of a li-diketone. US-A-5,451,628 describes the use of a ,,mixed-metal" stabilizer with hydrotalcite and antimony trioxide for enhancing thermostability.

Although the demands made on thermostability and aging stability can, in part, be met with these lead-free systems, the values measured for the electrical resistance are, without exception, lower than those of conventional lead stabilizers after a prolonged moisture action.

DE-A-3843581 describes thermoplastic PVC molding compositions which contain, as the stabilizer system, a combination consisting of a zinc soap, an ethylene vinylacetate copolymer hydrolysate, a hydrotalcite and, optionally, a basic calciumaluminum-hydroxy-phosphite. The electrical resistance characteristics of these molding compositions have, however, not been examined, since these molding compositions are not used for cable sheathings.

!t is the object of the present invention to use molding compositions based on halogen-containing polymers for cable sheatings, which satisfy the demands made on thermostability and aging stability.

This object is achieved according to the invention by the use of a molding composition, containing at least one halogen-containing polymer and a stabilizer composition, comprising at least one natural or synthetic hydrotalcite which is optionally surfacemodified, and i at least one basic calcium-aluminum-hydroxy compound, selected from (bl) basic calcium-aluminum-hydroxy-phosphites represented by the general formula (I) p, I s CClkl~ 3 CaXA2(OH) 2 3 )(Hp3)Y2. mH 2 O 0 wherein 2 <x 12, YPIand 2 0 <m 12 except for y=1, when 2 x <8; and/or (b2) basic calciumaluminumhydroxycarboiaterepresented by the general formula (Il)* CaA12(OH)((2+6)-] jA m H 2 0

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wherein 2< x <12 y 0 2 0 m 12, 1 and _1lli lilt II 4 is an aliphatic saturated, unsaturated, straight-chain or branched mono- or polyfunctional carboxylic acid anion having 1 to 22 carbon atoms or an aromatic or heteroaromatic mono- or polyfunctional carboxylic acid anion having 6 to 20 carbon atoms or combinations thereof, except for y=1 when 2 x 8, for cable sheathings.

The stabilizer composition used according to the invertion preferably comprises at least one liquid or solid, organic or inorganic zinc salt as a further component.

Cable sheatings which even after the prolonged action of moisture have resistance values corresponding to those of PVC cable sheatings having standard lead stabilizers are obtained by the inventive use of the above-mentioned molding composition.

Hydrotalcites are, for instance, described in DE-A-4425266, EP-A-0189899,

DE-A-

3843581, US-A-4,883,533, EP-A-0407139, DE-A-4031818, DE-A-4110835,

DE-A-

4117034, EP-A-0522810, DE-A-4439934, and US-A-5,352,723; compounds represented by the general formula are, described in DE-A-4106411, and compounds represented by the general formula (II) are, for instance, known from DE- A-4106404.

The carboxylic acid anion contained in the general formula (II) can, for instance, be selected from anions of malonic acid, succinic acid, adipic acid, fumaric acid, maleic acid, phthalic acid, isophthalic acid, terephthalic acid, pyridinic acid, benzoic acid, salicylic acid, tartronic acid, malic acid, tartaric acid, acetonedicarboxylic acid, oxalacetic acid, aconitic acid, citric acid and amino acid. The anions of fumaric acid and phthalic acid are preferred. Fumarates are particularly used.

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Y_ Component i.e. hydrotalcite, is preferably used in an amount of from 1 to 12 parts by weight, in particular in an amount of from 2 to 8 parts by weight, based on 100 parts by weight of the halogen-containing polymer.

The amount of component is preferably 0.5 to 10 parts by weight, in particular 1 to 3 parts by weight, based on 100 parts by weight of the halogen-containing polymers.

I.I In the calcium-zinc stabilizers used in the prior art, a large amount of zinc component is needed for guaranteeing the desired characteristics. As documented in the following I examplel, 0.8 part by weight of zinc laurate is, for instance, used in formulation V2 according to the prior art, whilst in the inventive compositions B1 and B2 only 0.45 and :0.3 parts by weight of zinc laurate are, respectively, needed. Formulations V4 and according to the prior art contain 1.05 and 1.6 parts by weight of zinc stearate whereas the inventive compositions B3 and B4 only require 0.35 and 0.40 parts by weight of zinc stearate. As follows from the examples which are given in the present invention, the amount of zinc, here in the form of zinc laurate and zinc stearate, respectively, can be reduced to 25% of the amount which has so far been needed in the prior art.

The liquid or solid, inorganic or organic zinc salt is used according to the invention in an amount which is needed for achieving the desired characteristics. This amount preferably ranges from 0.1 to 12 parts by weight, in particular from 0.5 to 7 parts by i weight, based on 100 parts by weight of the halogen-containing polymer. An amount of 0.5 to 2 parts by weight of zinc salt, based on 100 parts by weight of the halogencontaining polymer, is particularly preferred.

The zinc salt which is used according to the invention is, for instance, selected from zinc oxide, zinc sulfide, zinc caprylate, zinc laurate, zinc stearate, zinc behenate, zinc acetylacetonate, zinc arachinate, zinc borates, zinc stannates, and zinc 6 hydroxystannates. Zinc caprylate, zinc laurate, zinc stearate, zinc arachinate and zinc behenate are preferably used; zinc laurate and zinc stearate are used in a particularly preferred manner.

Polyvinyl chloride is preferably used according to the invention as the halogencontaining polymer.

The term polyvinyl chloride as used in the present invention covers standard homopolymers or copolymers of vinyl chloride as well as mixtures of such polyvinyl chloride compounds with other polymer compounds. Such polymers may have been prepared in any desired ways, by suspension, emulsion or block polymerization.

Their K value may, for instance, range from 50 to 100.

The stabilizer cumpositions used according to the invention may be combined with o o further heat stabilizers, light stabilizers and antioxidants. Such compounds, which are normally used as additives for chlorine-containing polymers, are, for instance, oxides and/or hydroxides of metals, such as calcium hydroxide or zinc oxide; zeolites or tincontaining stabilizers. Furthermore, organic stabilizers, such as 1,3-diketones or the metal salts thereof, polyols, isocyanurates, dihydropyridines, epoxides and phosphites and/or inorganic stabilizers such as garnets, modified hydrotalcites or other layer compounds, may be used.

According to the invention the molding compositions which are used for cable sheathings may contain additives that are normally used, for instance fillers (e.g.

chalk, kaolinite), pigments (such as titanium dioxide), flameproofing agents (such as magnesium hydroxide, aluminum hydroxide, antimony trioxide), reinforcing agents glass fibers, talcum) and plasticizers (phthalate, phosphate, polymer plasticizers, chlorinated paraffins).

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7 For setting the rheogical requirements, lubricants such as paraffin waxes, lowmolecular polyolefins, ester lubricants of mono- or polyvalent alcohols and mono- or dicarboxylic acids or amide waxes may be added to the halogen-containing polymers.

Moreover, further additives, such as antioxidants, UV and light stabilizers, such as sterically hindered amines, optical brightening agents and sulfur-containing compounds, in particular the sulfur-containing organic compounds used for producing tin-containing stabilizers, may be added to the chlorine-containing polymers.

The following examples will explain the invention. Unless otherwise specified, information which is given in parts or percentage refers to the weight.

:i The compositions which are designated by,,B" relate to stabilizer compositions used 2 according to the invention, whereas the compositions designated by are stabilizer S compositions which are not composed in accordance with the present invention.

SExample 1 100 parts of S-polyvinyl chloride, K value 70, 50 parts of diisodecyl phthalate, 50 parts of coated chalk, 0.1 part of bisphenol A, 0.4 part of lead stearate, 3.4 parts of tetrabasic lead sulfate, 0.3 part of calcium stearate and 0.2 part of paraffin wax were mixed for composition V1. A cable having an outer diameter of 2.92 mm and a conductor diameter of 1.3 mm was extruded with a single-screw laboratory extruder from said composition V1 in accordance with standard preparation methods.

A piece of said cable with a length of 5 m was stored in a water bath at 70°C to measure the long-time stability of the electrical resistance. The electrical resistance was determined before the beginning of water storage and after one year of water storage.

Example 2 :100 parts of S-polyvinyl chloride, K value 70, 50 parts of diisodecyl phthalate, 50 parts of coated chalk, 0.1 part of bisphenol A, 0.1 part of calcium stearate, 2.9 parts of hydrotalcite (Alkamizer 1, trade name), 0.8 part of zinc laurate and 0.2 part of paraffin wax were mixed for composition V2. The processability of composition V2 corresponds to composition V1. A cable was extruded with composition V2 under the same conditions as indicated in Example 1. This cable was stored in exactly the same manner as the cable of composition V1 in a water bath having a temperature of and the electrical resistance was measured prior to the beginning of water storage Sand after one year of water storage.

l Example 3 i "Composition B1 according to the invention was prepared from 100 parts of S-polyvinyl chloride, K value 70, 50 parts of diisodecyl phthalate, 50 parts of coated chalk, 0.1 part of bisphenol A, 3.0 parts of hydrotalcite (Alkamizer 1, trade name), 1.0 part of basic calcium-aluminum-hydroxy-phosphite, 0.45 part of zinc laurate and 0.2 part of I:3 paraffin wax. In this instance, too, the processing properties correspond to those of Icomposition V1. According to the invention, a cable with the same dimensions as described for V1 was also extruded from composition B1 and subsequently subjected S"to water storage at 70"C. The electrical resistance was measured by analogy with Examples 1 and 2.

Example 4 Composition B2 of the invention was prepared from 100 parts of polyvinyl chloride, K value 70, 50 parts of diisodecyl phthalate, 50 parts of coated chalk, 0.1 part of iii m m EJIUIIUHUEUURUJ I UUAlTiH~-- 9 bisphenol A, 2.0 parts of hydrotalcite (Alkamizer 1, trade name), 2.0 parts of basic calcium-aluminum-hydroxy-fumarate, 0.3 part of zinc laurate and 0.2 part of paraffin wax. Extrusion of the cable as well as water storage and measurement of the electrical resistance were performed under the same conditions as described in Examples 1 to 3.

The measurement results for the electrical resistance at the beginning of water storage and after one year of water storage are summarized in Table 1.

Table 1 Example K value [Mnkm] at 700C 1) directly after extrusion after one year of water storage at 1 3.102 2.803 2 2.984 0.540 3 3.187 3.019 4 3.177 3.124 1) The electrical resistance constant K [Mnkm] is calculated as follows:

I.R

K 1000 loglo(D/d) wherein D diameter [mm] of the cable d diameter [mm] of the conductor I length of the cable R resistance [Mn] of the cable.

A comparison of composition V1 and V2 shows that, as far as long-term characteristics under the action of moisture are concerned, composition V2 which L 77777-'7- V. 4 wk _11 contains the calcium-zinc stabilizer is considerably inferior, in its electrical resistance, to composition V1 having a lead stabilizer after one year of water storage at 70"C. By contrast, after one year of storage in water having a temperature of 70°C, the cables which are made from compositions B1 and B2 of u ie invention exhibit a value that is even above the value of composition V1 with the lead stabilizer when the elec'rical resistance is measured. Hence, these mixtures can advantageously be used under conditions where a high electrical resistance value is also required after a long time, in particular under the action of moisture.

Example As described in Example 1, a cable was extruded from the composition V3 consisting of 100 parts of poiyvinyl chloride (K value 70), 45 parts of TOTM (trioctyl trimellitate), parts of calcined kaoline, 6 parts of dibasic lead phthalate, 0.5 part of calcium stearate, 0.3 part of bisphenol A and 3 parts of antiimony trioxide, and a piece of said cable having a length of 5 m was subjected to water storage at 70"C. The electrical resistance was measured at the beginning of water storage and one year seer water storage at 700C.

Example 6 Composition V4 was prepared as in Example 5, except for the measure that instead of 6 parts of lead phthalate and 0.5 part of calcium stearate, 4 parts of hydrotalcite (Alkamizer 1, trade name), 1.05 parts of zinc stearate and 0.9 part of calcium stearate were used. A cable was also extruded from this mixture for subsequent water storage at 70°C, as described in Example 1. The electrical resistance was measured at the beginning and one year after water storage at U- I rs~-~B~BI lb PWB~P~4aa~L"~~ i 11 Example 7 The following components were used for composition V5: 100 parts of polyvir chloride, 45 parts of TOTM, 20 parts of calcined kaoline, 3 parts of antimony de, 1 part of hydrotalcite (Alkamizer 1, trade name), 0.6 part of bisphenol A, 1.6 p- of zinc stearate, 1.61 parts of dipentaerythritol, and 0.8 part of calcium laurate. As described in Example 1, a cable was extruded from this mixture for subsequent water storage at The electrical resistance was measured at the beginning and one year after water storage at Example 8 The inventive composition B3 is composed as follows: 100 parts of polyvinyl chloride, parts of TOTM, 20 parts of calcined kaoline, 0.3 part of bisphenol A, 3.1 parts of hydrotalcite (Alkamizer 1, trade name), 1.2 parts of calcium-aluminum-hydroxyphosphite, 0.35 part of zinc stearate and 3 parts of antimony trioxide. As described in Example 1, a cable was also extruded from this mixture for subsequent water storage at 70°C. The electrical resistance was measured at the beginning and one year after water storage at 700C.

Example 9 Apart from 100 parts of polyvinyl chloride, 45 parts of TOTM, 20 parts of calcined clay and 3 parts of antimony trioxide, the inventive composition B4 contained 0.3 part of bisphenol A, 3.3 parts of hydrotalcite (Alkamizer 1, trade name), 0.8 part of calciumaluminum-hydroxy-fumarate and 0.4 parts of zinc stearate. As described in Example 1, a cable was also extruded from this mixture for subsequent water storage at 700C.

The electrical resistance was measured at the bei.)nning and one year after water storage at -t y 0 2 0m 12, ./2 summarized in Table 2.

Table 2 Example directly after extrusio 5.438 6 5.254 7 5.371 8 5.211 9 5.562 K value [Mnkm] at n after one year of water storage at 5.342 0.784 0.367 5.195 5.422 ii

I

All examples yield comparable values with respect to the stabilizing characteristics and would also be usable under this aspect alone. It is only a measurement of the electrical resistance after prolonged water storage at 700C which reveals that apart from the known and presently wide-spread lead stabilizers based on lead phthalate it is only with the stabilizer compositions used according to the invention that a sufficiently high electrical resistance can be achieved in a permanent manner. In the first phase after preparation, calcium-zinc stabilizers which have so far been in common use yield an electrical resistance which is comparable to that of lead stabilizers, but upon the action of moisture this resistance drastically drops in the course of time.

Throughout this specification and the claims, the words "comprise", "comprises" and "comprising" are used in a nonexclusive sense.

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Claims

1. Use of a molding composition containing at least one halogen-containing polymer and a stabilizer composition, comprising at least one natural or synthetic hydrotalcite which is optionally surface- modified, and at least one basic calcium-aluminum-hydroxy compound selected from (bl) basic calcium-aluminum-hydroxy-phosphites represented by the general formula (I) .i CaxAl 2 (OH) 2 (x3-y)(H P 3 )y 2 m H 2 0 (I) whereir 2<x<12 2x+5 y 0 2 0 12, except for y=1 when 2 <x 8; and/or (b2) basic calcium-aluminum-hydroxy-carboxylates represented by the general L~l .~L~W 14 formula (II) CaAl 2 2 +6)-y]Ay/n mH20 (II) wherein 2<x<12, >y>0 2 S0< m 12, 1 <n 8, and i4 A" represents en aliphatic saturated, unsaturated, straight-chain or branched i mono- or polyfunctional carboxylic acid anion having 1 to 22 carbon atoms or S an aromatic or heteroaromatic mono- or polyfunctional carboxylic acid anion having 6 to 20 carbon atoms, or combinations thereof, V 'except for y=1, when 2 <x 8 for cable sheathings.

2. Use according to claim 1, characterized in that said stabilizer composition further contains at least one liquid or solid, organic or inorganic zinc salt.

3. Use according to claim 1 or 2, characterized in that said component is contained in said molding composition in an amount of from 1 to 12 parts by weight and component (bl) and/or (b2) is/are jointly contained in said molding composition in an amount of from 0.5 to 10 parts by weight, based on 100 parts by weight of halogen- containing polymer.

4. Use according to claim 3, characterized in that component is contained .n said molding composition in an amount of from 2 to 8 parts by weight and component (bl) and/or (bl) is/are jointly contained in said molding composition in an amount of from 1 to 3 parts by weight, based on 100 parts by weight of halogen-containing polymer. Use according to any one of claims 1 to 4, characterized in that said halogen- containing polymer is polyvinyl chloride. DATED THIS 20TH DAY OF OCTOBER 1997 BAERLOCHER GMBH By its Patent Attorneys: GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia rr-, '7ii1 1 1 Use of a Molding Composition Comprising Halogen-Containinq Polymers, for Cable Sheathinqs Abstract The present invention relates to the use of a molding composition, containing halogen-containing polymers, in particular polyvinyl chloride, and a special stabilizer composition for cable sheathings. Thanks to the stabilizer composition which contains at least one optionally surface-modified hydrotalcite, at least one basic calcium- aluminum-hydroxy-phosphite and/or at least one basic calcium-aluminum-hydroxy- carboxylate, and optionally at least one liquid or solid, organic or inorganic zinc salt, the high electrical resistance value of the molding composition remains constant over a long period of time, also under the action of moisture, as is required for cable sheathings. I, I