CA1061496A - Preparing thermo-plastic or elastomeric materials for cross-linking of grafted silane - Google Patents
Preparing thermo-plastic or elastomeric materials for cross-linking of grafted silaneInfo
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- CA1061496A CA1061496A CA235,826A CA235826A CA1061496A CA 1061496 A CA1061496 A CA 1061496A CA 235826 A CA235826 A CA 235826A CA 1061496 A CA1061496 A CA 1061496A
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- water
- acid
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- linking
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
- H01B3/46—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes silicones
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
- C08F8/42—Introducing metal atoms or metal-containing groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/48—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule in which at least two but not all the silicon atoms are connected by linkages other than oxygen atoms
- C08G77/50—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule in which at least two but not all the silicon atoms are connected by linkages other than oxygen atoms by carbon linkages
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
- H01B3/42—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes polyesters; polyethers; polyacetals
- H01B3/421—Polyesters
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- General Chemical & Material Sciences (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
- Organic Insulating Materials (AREA)
- Processes Specially Adapted For Manufacturing Cables (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Siloxane cross-linking of polyethylene is carried out under in situ development of water by chemical reaction between an organic acid and a non-hygroscopic metal oxide producing a neutral salt and water.
Specifically, an ester peroxide is used as additive to be mixed with silane and polyethylene. The ester peroxide decomposes during grafting in free acid, alcohol and graft initiators for obtaining the grafting of silane on polyethylene, and the acid reacts with zinc oxide or tin oxide, also used as additive, to obtain salt and water. Alternatively, stearic acid or adipic acid and zinc oxide or tin oxide are added to a polyethylene silane mixture to develop water and salt of the acid. The present invention is a useful improvement over the prior art in that it permits a more careful control of the stoichiometry of the cross-linking reaction re-sulting in a more uniform product while doing away with the necessity for a water bath.
Siloxane cross-linking of polyethylene is carried out under in situ development of water by chemical reaction between an organic acid and a non-hygroscopic metal oxide producing a neutral salt and water.
Specifically, an ester peroxide is used as additive to be mixed with silane and polyethylene. The ester peroxide decomposes during grafting in free acid, alcohol and graft initiators for obtaining the grafting of silane on polyethylene, and the acid reacts with zinc oxide or tin oxide, also used as additive, to obtain salt and water. Alternatively, stearic acid or adipic acid and zinc oxide or tin oxide are added to a polyethylene silane mixture to develop water and salt of the acid. The present invention is a useful improvement over the prior art in that it permits a more careful control of the stoichiometry of the cross-linking reaction re-sulting in a more uniform product while doing away with the necessity for a water bath.
Description
~06~496 1 BACKGROUND OF_THE INVENTION
~ The present invention relates to cross-linking 4 of thermoplastic or elastomeric material in the presence of molsture and on the basis of grafting silane on the 6 macro-molecules of the material. Preferably, but not 7 exclusively, the invention relates to enveloping elongated 8 stock, such as electrical cable, conductors, tubes, etc.
9 by such materials, such as olefi~-polymerizate or mixed olefin-polymerizates.
.11 12 The German patent application 1,794,028 13 discloses grafting of organofunctional trialcoxysilanes 14 upon polyethylene chains to obtain subsequently cross-linking in the presence of moisture~ The grafting is initiated 16 under utilization of radical initiators, such as peroxides, 17 e.g. dicumyl peroxide; di-tertbutylperoxide; 1,3-bis (tert, 18 butylperoxi-isopropyl) benzene, etc. Also,azo-compounds 19 such as azo-bisisobutyronitrile can be used as initiator.
The grafting of the organo-silane upon the polyethylene 21 molecules can be carried out during mechanical working, 22 whereby free radicals are intermediately produced.
24 Siloxane cross-linking requires the presence of small amounts of water within the extruded and grafted 26 material. This water is usually provided through diffusion 27 in that e.g. following extrusion the material is placed q~
into hot water, The duration of applying water depends on the thickness of the material layer into which water molecules are to diffuse. Also, the water temperature is another factor determining the rate of diffusion. By way of example, a cable to be used for transmitting l kilovolts may be provided with a polyethylene insulation of about 103 mm thickness. When using boiling water, cross-linking is completed to a satisfactory degree, if the cable is left in the water for about 30 min. The duration of water application is 10 to 20 fold longer when the water temperature is only 80C.
The present invention provides in a method of cross-linking thermo-plastic or elastomeric material in the presence of moisture, the material being prepared by grafting a silane compound onto the material, the improvement comprising the step of adding to and mixing with the material, compounds which form water by chemical reaction, the adding being carried out prior to grafting to obtain cross-linking of grafted silane through the water as formed in situ by the reaction and throughout the material.
~-~i - 2 -~'1 ~061496 It is an object of the present invention to 4 shorten the period needed for applying water to a graft polymer or the like for obtaining cross-linking.
7 It is another object of the present invention 8 to improve the siloxane cross-linking process.
In accordance with the preferred embodiment ll of the present invention, it is suggested to add additives 12 to an elastomeric or thermoplastic material which produce 13 water by chemical reaction within the material to obtain 14 cross-linking of the grafted silane. Specifically, an organic acid and a nonhygroscopic metal oxide are added 16 to a mixture that includes the macromolecules of 17 the basic material, e.g. polyethylene, the component to 18 be grafted e.g. silane and other additives to obtain a neutral 19 salt of that acid and water in situ to be available for condensation type cross-linking. The various components are 21 intimately mixed at first, e.g. either in a dry mixer-22 agitator or in a mixing extruder, whereby specifically the 23 metal salt particles are homogeneously distributed through-24 out the hcst material. The acid is preferably to be of the type that decomposes thermally so that the water 26 develops pursuant to the thermally induced grafting, but 27 only after the grafting has been completed.
1 It is preferred to shape the product immediately
~ The present invention relates to cross-linking 4 of thermoplastic or elastomeric material in the presence of molsture and on the basis of grafting silane on the 6 macro-molecules of the material. Preferably, but not 7 exclusively, the invention relates to enveloping elongated 8 stock, such as electrical cable, conductors, tubes, etc.
9 by such materials, such as olefi~-polymerizate or mixed olefin-polymerizates.
.11 12 The German patent application 1,794,028 13 discloses grafting of organofunctional trialcoxysilanes 14 upon polyethylene chains to obtain subsequently cross-linking in the presence of moisture~ The grafting is initiated 16 under utilization of radical initiators, such as peroxides, 17 e.g. dicumyl peroxide; di-tertbutylperoxide; 1,3-bis (tert, 18 butylperoxi-isopropyl) benzene, etc. Also,azo-compounds 19 such as azo-bisisobutyronitrile can be used as initiator.
The grafting of the organo-silane upon the polyethylene 21 molecules can be carried out during mechanical working, 22 whereby free radicals are intermediately produced.
24 Siloxane cross-linking requires the presence of small amounts of water within the extruded and grafted 26 material. This water is usually provided through diffusion 27 in that e.g. following extrusion the material is placed q~
into hot water, The duration of applying water depends on the thickness of the material layer into which water molecules are to diffuse. Also, the water temperature is another factor determining the rate of diffusion. By way of example, a cable to be used for transmitting l kilovolts may be provided with a polyethylene insulation of about 103 mm thickness. When using boiling water, cross-linking is completed to a satisfactory degree, if the cable is left in the water for about 30 min. The duration of water application is 10 to 20 fold longer when the water temperature is only 80C.
The present invention provides in a method of cross-linking thermo-plastic or elastomeric material in the presence of moisture, the material being prepared by grafting a silane compound onto the material, the improvement comprising the step of adding to and mixing with the material, compounds which form water by chemical reaction, the adding being carried out prior to grafting to obtain cross-linking of grafted silane through the water as formed in situ by the reaction and throughout the material.
~-~i - 2 -~'1 ~061496 It is an object of the present invention to 4 shorten the period needed for applying water to a graft polymer or the like for obtaining cross-linking.
7 It is another object of the present invention 8 to improve the siloxane cross-linking process.
In accordance with the preferred embodiment ll of the present invention, it is suggested to add additives 12 to an elastomeric or thermoplastic material which produce 13 water by chemical reaction within the material to obtain 14 cross-linking of the grafted silane. Specifically, an organic acid and a nonhygroscopic metal oxide are added 16 to a mixture that includes the macromolecules of 17 the basic material, e.g. polyethylene, the component to 18 be grafted e.g. silane and other additives to obtain a neutral 19 salt of that acid and water in situ to be available for condensation type cross-linking. The various components are 21 intimately mixed at first, e.g. either in a dry mixer-22 agitator or in a mixing extruder, whereby specifically the 23 metal salt particles are homogeneously distributed through-24 out the hcst material. The acid is preferably to be of the type that decomposes thermally so that the water 26 develops pursuant to the thermally induced grafting, but 27 only after the grafting has been completed.
1 It is preferred to shape the product immediately
2 after grafting, if the thermally induced grafting sets also ~ the reac~on into motion, which produces the water, because 4 cross-linking will commence as soon as water is available in the material.
7 rrhe water as developed in situ is provided 8 in stoichiometrically determinable quantities and can be 9 metered very accurately accordingly. The invention obviates the need for placing the material into water to 11 obtain the diffusion, because diffusion is no longer 12 necessary; the water is developed in the material itself.
14 In accordance with the preferred form of practicing the invention, monobasic or multibasic fatty 16 acids, such as stearic acid, adipic acid, e~c. are added 17 together with non-hygroscopic metal oxides, preferably 18 tin or zinc oxides. The reaction between the acid and the 19 oxide produces water and a residue compound which is indifferent as far as the plastic material generally and 21 cross-linking specifically is concerned. The chemically 22 indifferent residue is e.g. a metal salt which does not 23 interfere with the cross-linking nor does it have any ~4 detrimental influence on the salient properties of the extrudate.
27 The water as developed by chemical reaction 28 in the material may initiate and carry out the cross-linking 29 under the promoting influence of one or more catalysts.
m6l4s6 1 The invention has the specific advantage here that the 2 water is quite evenly distributed and homogeneously
7 rrhe water as developed in situ is provided 8 in stoichiometrically determinable quantities and can be 9 metered very accurately accordingly. The invention obviates the need for placing the material into water to 11 obtain the diffusion, because diffusion is no longer 12 necessary; the water is developed in the material itself.
14 In accordance with the preferred form of practicing the invention, monobasic or multibasic fatty 16 acids, such as stearic acid, adipic acid, e~c. are added 17 together with non-hygroscopic metal oxides, preferably 18 tin or zinc oxides. The reaction between the acid and the 19 oxide produces water and a residue compound which is indifferent as far as the plastic material generally and 21 cross-linking specifically is concerned. The chemically 22 indifferent residue is e.g. a metal salt which does not 23 interfere with the cross-linking nor does it have any ~4 detrimental influence on the salient properties of the extrudate.
27 The water as developed by chemical reaction 28 in the material may initiate and carry out the cross-linking 29 under the promoting influence of one or more catalysts.
m6l4s6 1 The invention has the specific advantage here that the 2 water is quite evenly distributed and homogeneously
3 developed in the material, so that cross-linking can
4 occur everywhere. A homogenic distribution of the cross-links is of specific advantage for cable with regard to 6 its mechanical and electrical properties. Diffusion 7 of water cannot possibly produce a similar degree of 8 homogeneity. It has to be observed here that water diffuses 9 preferably through amorphous, non-crystalline regions of 0 the polyethylene so that the density of cross-links will 11 be much lower in the crystaline regions.
13 It is of particular advantage if one uses a pero-14 xide as additives which forms an acid upon thermal decomposition. For example, ester-peroxide can be used 16 together with tin or zinc oxide. Specifically, tert.butyl-17 peroxy-isonanoate (tert. butyl per -3,5,5 tri-methylhexanoate) 18 is used with advantage, but other ester peroxides can also 19 be used. It should be noted that undesired premature peroxide cross-linking of the polyethylene through C-C
21 bridges will occur to a minor extent only when these peroxides 22 are used. On the other hand, they furnish a long chain of 23 carbonic acid, such as isononanoic acia or 3,5,5 trimethyl-24 hexanoic acid in addition to tert. butanol when decomposing thermally. The reaction is as follows:
CH CH
28 CH - C - O - O - C - R -~ CH - C - O + O - C - R
29 3 1 ll 3 I jl CH O CH O
1 wherein R represents a 3,5,5-tri-methyl-hexyl radical 2 or a isononanyl radical and the astrix (~ ) denotes the 3 active sites available for radical reaction.
The tert. butoxy-radical and the acyl radical 6 induce sites for radicals on the polyethylene macro-q molecules and initiate grafting, while these locations 8 themselves are deactivated by transfer of hydrogen. For 9 each molecule of peroxide entering the reaction one obtains of one molecule tert. butanol and one molecule of isononanoic 11 acid.
1~ .
13 Depending on the reactivity of the used organo-14 silane~grafting is mostly a rather quickly running process.
This is particularly the case when vinyl or allyl groups 16 remain as organic groups at the silicon atoms. The speed 17 of grafting is then always determined by the speed of 18 thermal decomposition of the peroxide grafting as 19 completed prior to shaping the plastic by the extrusion die.
21 As stated, non-hygroscopic metal oxides, such 22 as tin oxide or zinc-oxide are preferably to be used/and 23 these oxides react with the acid as resulting prior tG
24 the thermal decomposition of the peroxide. Particularly, the high temperature needed and used for grafting causes 26 that acid to react with the metal oxide as follows (using 27 SnO as example):
28 CH3 C~3 1 3 IH3 29 CH3~C~CH2~CH~CH2~COOH + SnO--~(CH3-C-CH2-CH-CH2-COO) Sn + H20 1 Thus, the reaction product is water and the 2 Sn salt of the isononanoic acid. The water developed ~ in that fashion depends on the amount of peroxide used 4 as additive. The usual peroxide amount ranges from 0.2 to 0.3 % (by weight) with reference to the base polymer 6 (polyethylene),and that amount will yield about 0.01 %
7 by weight water. The base material contains already some 8 water, about 0.01 to 0.015 %, and the added amount of 9 0.01 ~ as resulting from the afore-described reaction suffices for the cross-linking reaction. This is parti-11 cularly true because the H 0 content used for hydrolysis 12 of the alcoxy group in the silanol condensation reaction is 13 to some extent restored on cross-linking and can again 14 participate in the relation in accordance with the following scheme:
7 ~-CH2-CH2-Si-OCH3+H20 ~ ~-CH -CH2-si-OH + CH OH
19 ~-CH2-CH -Si-OH + HO-Si-CH2-CH2-~ -~ H O + ~-CH -CH -Si-O-CH -CH
21 In accordance with the preferred form of practi-22 cing the invention one uses about 0.5 to 2 parts metal oxide 23 per 100 parts polyethylene as base material. The combination 24 use thereof with the peroxides forming acids upon thermal decomposition adds the advantage that further catalysts 26 are not needed. The salt formed upon the reaction of the 1 isononanoic acid and the tin oxide has a catalytic effect 2 on the alcoxyhydrolysis as well as on the condensation ~ reaction leading to cross-linking. Thus, one does not need 4 dibutyl-tin - dilaurate as commonly used as catalyst for silanol condensation. In other words, the (still needed) 6 catalyst for cross-linking is developed in the material 7 itself by chemical reaction following the grafting. The 8 inventive process, therefore, combines the internal formation 9 of water with induction of active sites on the polyethylene macromolecules for grafting, whereby additionally the cata-11 lytist for cross-linking is produced as a by-product.
13 The metal oxides may, for example, be added 14 to the granular or powdery polyethylene, when in a fluidized 1~ state and while being agitated. For example, the powdery 16 polyethylene is charged in a fast rotating dry mixer. The 17 silane, the peroxide, and possibly, activators and ageing 18 protectors (anti-oxidants) are added as solution. That solution 19 may also contain the metal oxi~e in suspension. The agitation and frictional heating of the powder produces diffusion of the 21 liquidous additives, but the oxide particles are squeezed 22 into the surface of the softened polyethylene powder particles.
23 The temperature to be maintained here, either through friction 24 or external heating or both is about 80 to 95 C. With or without such prior agitation, a grafting extruder receiving 26 the polyethylene plus additive mixture will ensure that the 1 metal is homogenously distributed in the extruded poly-2 ethylene, in the worm and barrel region of the extruder.
4The following examples demonstrate particular use of the invention:
7 E x a m p 1 e 9The following mixture was used: -parts 0 . (by weight) 11Polyethylene lupolen 1810 H 100 12Peroxide (tert. butyl-per-isonanoate) 0.23 13Vinyl-trimethoxysilane 2.0 14Activator OC ~ 0.18 Anox HB - O 5 16 ZnO
18 wherein Anox HB is a product availabl~ under that name 19 and consisting of 2,2,4 trimethyl-dihydro-quinoline and the activator is triallylcyanurate.
22 15 kilograms polyethylene were mixed in a dry 23 mixer with the corresponding quantity of vinyltrimetho-24 xysilane and the latter liquid contains all other components needed for cross-linking and it contained also the ZnO in 26 suspenslon. The temperature was raised rather rapidly to 2~ .
~ r~Q ~g 9 ~061496 1 95 C as the mixer assumed a stirring speed of about 2 1700 RPM. The liquid additives diffused into the powdery 3 polyethylene within a few minutes and the metal oxide 4 was mechanically integrated in the powder.
6 The mixture was charged in an extruder of q 45 mm barrel length and with an L/D ratio of 20 and the 8 material was extruded at an exit temperature of 220 C.
9 During the extrusion, the following reactions occurred whereby each follower reaction has a specific purpose 11 and task.
13 The primary reaction was the decompositoning 14 of the peroxide in two radicals. The first follower reaction caused formationof a radical to the polyethylene macro-16 molecules under development of free acid and alcohol.
17 The second follower reaction was the grafting of the organo-18 silane upon the macromolecules. The third follower reaction 19 was the reaction of the just formed acid with the metal oxide under formation of water and of a metal salt to serve 21 as catalyst. The fourth follower reaction was the hydrolysis 22 of the alcoxy group at the grafted silane followed by 23 condensation and cross-linking by means of the catalyst 24 as formed in the third follower reaction, while water is restored to serve in ~he hydrolysis.
106~496 1 The following example demonstrates use of the 2 invention without including the peroxide in the reaction.
4 E x a m p 1 e 2 S
6 Polyethylene Lupolen 1800 M 100 7 Tert. butyl-peroxy-isonanoate 0.2 B 8 Perkadox 14 ~ 0.01 9 Vinyl-trimethoxysilane 2.0 0 ZnO 0.5 Stearic acid 0.5 12 Activator OC 0.06 13 Anox HB 0.5 Mixing and preparation of the mixture is carried 16 out as ln example 1. Water is developed when the stearic 17 acid reacts with the ZnO.
19 It can thus be seen that siloxane cross-linking is considerably improved by the invention, because the 21 extruded product does not have to be placed in hot water, 22 and in cases one does not even need a separate catalyst. If 23 one uses a particular peroxide, namely an ester-peroxide, ~4 i.e. a perester, such as the tert. butyl-per-3,5,5-trimeth-ylhexanoate, one obtains the rather complex sequence of 26 reaction as was outlined above.
~f f r ~ J ~ ~n ~061496 The invention is not limited to the embodiments described above, but all changes and modifications thereof and including any disclosure in Canadian patent application Serial No. 223,679 filed August 18, 1975 in the name of the applicant herein, but not constituting departures from the spirit and scope of the invention are intended to be included. It should be noted that the water-producing reaction is quite compatible with prior grafting of an anti-oxidant as described also in my copending application (D-5805). It is pointed out, however, that extruding, for example, a sheath around a conductor for purposes of cable making will result in a unique product as per the present inventionin that water developed in situ in the extruder and as part of the thermal processing of the extruded polyethylene with grafted silane causes quite uniformly cross-linking so that a thermo-setting plastic envelope or sheath is produced around the conductor, which has configuration -and shape as extruded. The product is, therefore, different from sheathed conductors, where the water was caused to diffuse into the sheath from the outside.
- lla -
13 It is of particular advantage if one uses a pero-14 xide as additives which forms an acid upon thermal decomposition. For example, ester-peroxide can be used 16 together with tin or zinc oxide. Specifically, tert.butyl-17 peroxy-isonanoate (tert. butyl per -3,5,5 tri-methylhexanoate) 18 is used with advantage, but other ester peroxides can also 19 be used. It should be noted that undesired premature peroxide cross-linking of the polyethylene through C-C
21 bridges will occur to a minor extent only when these peroxides 22 are used. On the other hand, they furnish a long chain of 23 carbonic acid, such as isononanoic acia or 3,5,5 trimethyl-24 hexanoic acid in addition to tert. butanol when decomposing thermally. The reaction is as follows:
CH CH
28 CH - C - O - O - C - R -~ CH - C - O + O - C - R
29 3 1 ll 3 I jl CH O CH O
1 wherein R represents a 3,5,5-tri-methyl-hexyl radical 2 or a isononanyl radical and the astrix (~ ) denotes the 3 active sites available for radical reaction.
The tert. butoxy-radical and the acyl radical 6 induce sites for radicals on the polyethylene macro-q molecules and initiate grafting, while these locations 8 themselves are deactivated by transfer of hydrogen. For 9 each molecule of peroxide entering the reaction one obtains of one molecule tert. butanol and one molecule of isononanoic 11 acid.
1~ .
13 Depending on the reactivity of the used organo-14 silane~grafting is mostly a rather quickly running process.
This is particularly the case when vinyl or allyl groups 16 remain as organic groups at the silicon atoms. The speed 17 of grafting is then always determined by the speed of 18 thermal decomposition of the peroxide grafting as 19 completed prior to shaping the plastic by the extrusion die.
21 As stated, non-hygroscopic metal oxides, such 22 as tin oxide or zinc-oxide are preferably to be used/and 23 these oxides react with the acid as resulting prior tG
24 the thermal decomposition of the peroxide. Particularly, the high temperature needed and used for grafting causes 26 that acid to react with the metal oxide as follows (using 27 SnO as example):
28 CH3 C~3 1 3 IH3 29 CH3~C~CH2~CH~CH2~COOH + SnO--~(CH3-C-CH2-CH-CH2-COO) Sn + H20 1 Thus, the reaction product is water and the 2 Sn salt of the isononanoic acid. The water developed ~ in that fashion depends on the amount of peroxide used 4 as additive. The usual peroxide amount ranges from 0.2 to 0.3 % (by weight) with reference to the base polymer 6 (polyethylene),and that amount will yield about 0.01 %
7 by weight water. The base material contains already some 8 water, about 0.01 to 0.015 %, and the added amount of 9 0.01 ~ as resulting from the afore-described reaction suffices for the cross-linking reaction. This is parti-11 cularly true because the H 0 content used for hydrolysis 12 of the alcoxy group in the silanol condensation reaction is 13 to some extent restored on cross-linking and can again 14 participate in the relation in accordance with the following scheme:
7 ~-CH2-CH2-Si-OCH3+H20 ~ ~-CH -CH2-si-OH + CH OH
19 ~-CH2-CH -Si-OH + HO-Si-CH2-CH2-~ -~ H O + ~-CH -CH -Si-O-CH -CH
21 In accordance with the preferred form of practi-22 cing the invention one uses about 0.5 to 2 parts metal oxide 23 per 100 parts polyethylene as base material. The combination 24 use thereof with the peroxides forming acids upon thermal decomposition adds the advantage that further catalysts 26 are not needed. The salt formed upon the reaction of the 1 isononanoic acid and the tin oxide has a catalytic effect 2 on the alcoxyhydrolysis as well as on the condensation ~ reaction leading to cross-linking. Thus, one does not need 4 dibutyl-tin - dilaurate as commonly used as catalyst for silanol condensation. In other words, the (still needed) 6 catalyst for cross-linking is developed in the material 7 itself by chemical reaction following the grafting. The 8 inventive process, therefore, combines the internal formation 9 of water with induction of active sites on the polyethylene macromolecules for grafting, whereby additionally the cata-11 lytist for cross-linking is produced as a by-product.
13 The metal oxides may, for example, be added 14 to the granular or powdery polyethylene, when in a fluidized 1~ state and while being agitated. For example, the powdery 16 polyethylene is charged in a fast rotating dry mixer. The 17 silane, the peroxide, and possibly, activators and ageing 18 protectors (anti-oxidants) are added as solution. That solution 19 may also contain the metal oxi~e in suspension. The agitation and frictional heating of the powder produces diffusion of the 21 liquidous additives, but the oxide particles are squeezed 22 into the surface of the softened polyethylene powder particles.
23 The temperature to be maintained here, either through friction 24 or external heating or both is about 80 to 95 C. With or without such prior agitation, a grafting extruder receiving 26 the polyethylene plus additive mixture will ensure that the 1 metal is homogenously distributed in the extruded poly-2 ethylene, in the worm and barrel region of the extruder.
4The following examples demonstrate particular use of the invention:
7 E x a m p 1 e 9The following mixture was used: -parts 0 . (by weight) 11Polyethylene lupolen 1810 H 100 12Peroxide (tert. butyl-per-isonanoate) 0.23 13Vinyl-trimethoxysilane 2.0 14Activator OC ~ 0.18 Anox HB - O 5 16 ZnO
18 wherein Anox HB is a product availabl~ under that name 19 and consisting of 2,2,4 trimethyl-dihydro-quinoline and the activator is triallylcyanurate.
22 15 kilograms polyethylene were mixed in a dry 23 mixer with the corresponding quantity of vinyltrimetho-24 xysilane and the latter liquid contains all other components needed for cross-linking and it contained also the ZnO in 26 suspenslon. The temperature was raised rather rapidly to 2~ .
~ r~Q ~g 9 ~061496 1 95 C as the mixer assumed a stirring speed of about 2 1700 RPM. The liquid additives diffused into the powdery 3 polyethylene within a few minutes and the metal oxide 4 was mechanically integrated in the powder.
6 The mixture was charged in an extruder of q 45 mm barrel length and with an L/D ratio of 20 and the 8 material was extruded at an exit temperature of 220 C.
9 During the extrusion, the following reactions occurred whereby each follower reaction has a specific purpose 11 and task.
13 The primary reaction was the decompositoning 14 of the peroxide in two radicals. The first follower reaction caused formationof a radical to the polyethylene macro-16 molecules under development of free acid and alcohol.
17 The second follower reaction was the grafting of the organo-18 silane upon the macromolecules. The third follower reaction 19 was the reaction of the just formed acid with the metal oxide under formation of water and of a metal salt to serve 21 as catalyst. The fourth follower reaction was the hydrolysis 22 of the alcoxy group at the grafted silane followed by 23 condensation and cross-linking by means of the catalyst 24 as formed in the third follower reaction, while water is restored to serve in ~he hydrolysis.
106~496 1 The following example demonstrates use of the 2 invention without including the peroxide in the reaction.
4 E x a m p 1 e 2 S
6 Polyethylene Lupolen 1800 M 100 7 Tert. butyl-peroxy-isonanoate 0.2 B 8 Perkadox 14 ~ 0.01 9 Vinyl-trimethoxysilane 2.0 0 ZnO 0.5 Stearic acid 0.5 12 Activator OC 0.06 13 Anox HB 0.5 Mixing and preparation of the mixture is carried 16 out as ln example 1. Water is developed when the stearic 17 acid reacts with the ZnO.
19 It can thus be seen that siloxane cross-linking is considerably improved by the invention, because the 21 extruded product does not have to be placed in hot water, 22 and in cases one does not even need a separate catalyst. If 23 one uses a particular peroxide, namely an ester-peroxide, ~4 i.e. a perester, such as the tert. butyl-per-3,5,5-trimeth-ylhexanoate, one obtains the rather complex sequence of 26 reaction as was outlined above.
~f f r ~ J ~ ~n ~061496 The invention is not limited to the embodiments described above, but all changes and modifications thereof and including any disclosure in Canadian patent application Serial No. 223,679 filed August 18, 1975 in the name of the applicant herein, but not constituting departures from the spirit and scope of the invention are intended to be included. It should be noted that the water-producing reaction is quite compatible with prior grafting of an anti-oxidant as described also in my copending application (D-5805). It is pointed out, however, that extruding, for example, a sheath around a conductor for purposes of cable making will result in a unique product as per the present inventionin that water developed in situ in the extruder and as part of the thermal processing of the extruded polyethylene with grafted silane causes quite uniformly cross-linking so that a thermo-setting plastic envelope or sheath is produced around the conductor, which has configuration -and shape as extruded. The product is, therefore, different from sheathed conductors, where the water was caused to diffuse into the sheath from the outside.
- lla -
Claims (18)
1. In a method of cross-linking thermo-plastic or elastomeric material in the presence of moisture, the material being prepared by grafting a silane compound onto the material, the improvement comprising the step of adding to and mixing with the material, compounds which form water by chemical reaction, the adding being carried out prior to grafting to obtain cross-linking of grafted silane through the water as formed in situ by the reaction and throughout the material.
2. In a method as in claim 1, wherein the formation of water is carried out by heating the material.
3. In a method as in claim 1, wherein the formation of water occurs during thermally induced grafting.
4. In a method as in claim 1, wherein the compounds added are mono-basic or multi-basic fatty acid and non-hygroscopic metal oxides.
5. In a method as in claim 4, wherein the acid is stearic or adipic acid, the metal oxide being tin or zinc oxide.
6. In a method as in claim 1, wherein the compounds are a peroxide forming an organic acid upon thermal decompo-sitioning and a non-hygroscopic metal oxide combining with the acid to form a neutral salt and water.
7. In a method as in claim 6, the peroxide being an ester-peroxide.
8. Method as in claim 7, using tert. butyl-per 3,5,5 trimethylhexanoate as an ester-peroxide.
9. In a method as in claim 6, 7 or 8 said metal oxide being tin oxide or zinc oxide.
10. Method as in claim 4, wherein a metal oxide is added at no more than 10 parts by weight per 100 parts of the material.
11. A method as claimed in claim 10, wherein a metal oxide is added in an amount from 0.5 to 2 parts by weight per 100 parts of material.
12. Method as in claim 1, wherein the compounds include metal oxide suspended in a solution that includes silane and the solution is mixed with the thermoplastic or elastomeric material.
13. In a method as in claim 12, wherein the thermoplastic or elastomeric material is provided in granular or powdery consistency, and the silane compound as well as said material compounds being added and agitated to obtain diffusion of the compounds into the granular or powder particles.
14. In a method as in claim 1, wherein the material is extruded following the adding of the silane compound and of said material compounds, the chemical reaction occurring during grafting.
15. In a method as in claim 1, wherein the material is polyethylene type polymer, the compounds are (i) a peroxide forming an organic acid upon thermal decompositioning preceding grafting proper, and (ii) tin or zinc oxide.
16. In a method as in claim 15, using about 0.5 to 2 parts metal oxide per 100 parts polymer.
17. In a method as in claim 15, using tert.-butyl- per 3,5,5 trimethyl-hexanoate.
18. In a method as in claim 15, wherein the polymer is provided in granular or powdery consistency, the silane compound and the tin oxide or zinc oxide being added to the granular or powdery material, and agitated therewith to obtain diffusion into the granular or powder particles; and extruding the resulting mixture.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19742444829 DE2444829A1 (en) | 1974-09-19 | 1974-09-19 | PROCESS FOR THE PRODUCTION OF THERMOPLASTICS OR ELASTOMERS THAT CAN BE CROSSED BY PLUGGING ON A SILANE COMPOUND IN THE PRESENCE OF MOISTURE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1061496A true CA1061496A (en) | 1979-08-28 |
Family
ID=5926241
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA235,826A Expired CA1061496A (en) | 1974-09-19 | 1975-09-18 | Preparing thermo-plastic or elastomeric materials for cross-linking of grafted silane |
Country Status (11)
| Country | Link |
|---|---|
| US (1) | US4048129A (en) |
| JP (1) | JPS5150954A (en) |
| AR (1) | AR214966A1 (en) |
| BE (1) | BE831461A (en) |
| BR (1) | BR7505914A (en) |
| CA (1) | CA1061496A (en) |
| DE (1) | DE2444829A1 (en) |
| FR (1) | FR2285419A1 (en) |
| GB (1) | GB1500030A (en) |
| IT (1) | IT1040883B (en) |
| NL (1) | NL161783C (en) |
Families Citing this family (31)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4192842A (en) * | 1977-07-21 | 1980-03-11 | General Electric Company | Method for casting ultrathin methylpentene polymer membranes |
| US4132824A (en) * | 1977-07-21 | 1979-01-02 | General Electric Company | Method for casting ultrathin methylpentene polymer membranes |
| JPS5483089A (en) * | 1977-12-15 | 1979-07-02 | Sekisui Chem Co Ltd | Preparation of silane-modified ethylene resin |
| AU4199378A (en) * | 1977-12-20 | 1979-06-28 | British Steel Corp | Production of cross-linked polyolefine articles |
| US4400429A (en) * | 1980-12-22 | 1983-08-23 | National Distillers And Chemical Corporation | Tree retardant additive composition for polymeric insulation |
| FR2557879A1 (en) * | 1984-01-06 | 1985-07-12 | Neste Oy | PROCESS AND DEVICE FOR THE MANUFACTURE OF SHAPED ARTICLES CONTAINING A CROSSLINKED POLYOLEFIN |
| WO1985003511A1 (en) * | 1984-02-03 | 1985-08-15 | Neste Oy | Polyolefin with good adhesion properties |
| ZA862690B (en) * | 1985-04-22 | 1988-11-30 | Hri Inc | Catalytic two-stage co-processing of coal/oil feedstocks |
| US4732939A (en) * | 1986-01-20 | 1988-03-22 | Sumitomo Bakelite Company Limited | Flame-retardant olefinic resin compositions |
| JPS62215646A (en) * | 1986-03-17 | 1987-09-22 | Mitsubishi Petrochem Co Ltd | Propylene polymer composition |
| US4759992A (en) * | 1986-09-10 | 1988-07-26 | Uniroyal Chemical Company, Inc. | Process for coating moisture-curable low molecular weight polymers and composites thereof |
| JP2541567B2 (en) * | 1987-07-21 | 1996-10-09 | 三井石油化学工業株式会社 | Fiber material for reinforcement |
| US4822857A (en) * | 1987-12-22 | 1989-04-18 | Shell Oil Company | Method of grafting silane compounds to block copolymers |
| US5264515A (en) * | 1989-04-10 | 1993-11-23 | Rheox, Inc. | Moisture curable compositions and method of curing moisture curable compositions |
| JPH081531Y2 (en) * | 1991-09-09 | 1996-01-17 | タツタ電線株式会社 | Heat-resistant / flexible / wear-resistant coating robot cables |
| JPH0523333U (en) * | 1991-09-09 | 1993-03-26 | タツタ電線株式会社 | Heat-resistant / flexible / wear-resistant coated robot cable |
| JPH0523337U (en) * | 1991-09-09 | 1993-03-26 | タツタ電線株式会社 | Heat-resistant / flexible / wear-resistant coated robot cable |
| JPH0523335U (en) * | 1991-09-09 | 1993-03-26 | タツタ電線株式会社 | Heat-resistant / flexible / wear-resistant coated robot cable |
| JPH0523332U (en) * | 1991-09-09 | 1993-03-26 | タツタ電線株式会社 | Heat-resistant / flexible / wear-resistant coated robot cable |
| JPH0523334U (en) * | 1991-09-09 | 1993-03-26 | タツタ電線株式会社 | Heat-resistant / flexible / wear-resistant coated robot cable |
| JPH0523338U (en) * | 1991-09-09 | 1993-03-26 | タツタ電線株式会社 | Heat-resistant / flexible / wear-resistant coated robot cable |
| US5639818A (en) * | 1994-03-11 | 1997-06-17 | Quantum Chemical Corporation | Peroxide modified PP/PE blends with superior melt strength |
| CA2161712A1 (en) * | 1994-11-03 | 1996-05-04 | Ketan N. Shah | Silane modified elastomeric compositions and articles made therefrom |
| WO2004065092A1 (en) * | 2003-01-22 | 2004-08-05 | Wellstream International Limited | Process for manufacturing a flexible tubular pipe having extruded layers made of crosslinked polyethylene |
| US7202309B2 (en) * | 2003-09-12 | 2007-04-10 | Momentive Performance Materials Inc. | Process for crosslinking thermoplastic polymers with silanes employing peroxide blends and the resulting crosslinked thermoplastic polymers |
| CN100457798C (en) * | 2006-07-18 | 2009-02-04 | 浙江工业大学 | Process for preparing silane crosslinked polyethylene by room temperature crosslinking |
| US20080114134A1 (en) * | 2006-11-14 | 2008-05-15 | General Electric Company | Process for crosslinking thermoplastic polymers with silanes employing peroxide blends, the resulting crosslinked thermoplastic polymer composition and articles made therefrom |
| DE102006059295B4 (en) * | 2006-12-11 | 2009-12-17 | Kometra Kunststoff-Modifikatoren Und -Additiv Gmbh | Hydrolyzed silane-grafted olefin homo- and (block) copolymers and processes for their preparation |
| DE102009033710A1 (en) * | 2009-07-18 | 2011-01-20 | Evonik Goldschmidt Gmbh | Use of metal salts of a carboxylic acid in the production of polyurethane systems |
| KR20120083419A (en) * | 2009-09-18 | 2012-07-25 | 유니온 카바이드 케미칼즈 앤드 플라스틱스 테크날러지 엘엘씨 | Process for making crosslinked injection molded articles |
| EP2690115B1 (en) * | 2012-07-24 | 2018-02-21 | Borealis AG | Slow partial cross-linking polyolefin composition for improving disinfectant resistance of an article |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3503943A (en) * | 1965-10-21 | 1970-03-31 | Exxon Research Engineering Co | Silane modified ethylene-propylene terpolymer |
| BE794718Q (en) * | 1968-12-20 | 1973-05-16 | Dow Corning Ltd | OLEFINS CROSS-LINKING PROCESS |
| US3644315A (en) * | 1969-03-14 | 1972-02-22 | Exxon Research Engineering Co | Moisture-curable polymers |
| US3830872A (en) * | 1971-09-01 | 1974-08-20 | Dart Ind Inc | Use of xylene in controlling melt flow of modified polyolefin compositions |
-
1974
- 1974-09-19 DE DE19742444829 patent/DE2444829A1/en not_active Withdrawn
-
1975
- 1975-07-11 IT IT50476/75A patent/IT1040883B/en active
- 1975-07-17 BE BE158379A patent/BE831461A/en unknown
- 1975-07-22 FR FR7522892A patent/FR2285419A1/en not_active Withdrawn
- 1975-08-07 GB GB33024/75A patent/GB1500030A/en not_active Expired
- 1975-08-13 AR AR259992A patent/AR214966A1/en active
- 1975-09-02 JP JP50105695A patent/JPS5150954A/en active Pending
- 1975-09-08 US US05/611,519 patent/US4048129A/en not_active Expired - Lifetime
- 1975-09-15 BR BR7505914*A patent/BR7505914A/en unknown
- 1975-09-17 NL NL7510938.A patent/NL161783C/en active
- 1975-09-18 CA CA235,826A patent/CA1061496A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AR214966A1 (en) | 1979-08-31 |
| DE2444829A1 (en) | 1976-04-08 |
| NL7510938A (en) | 1976-03-23 |
| BR7505914A (en) | 1976-08-03 |
| IT1040883B (en) | 1979-12-20 |
| BE831461A (en) | 1975-11-17 |
| NL161783C (en) | 1980-03-17 |
| GB1500030A (en) | 1978-02-08 |
| US4048129A (en) | 1977-09-13 |
| NL161783B (en) | 1979-10-15 |
| FR2285419A1 (en) | 1976-04-16 |
| JPS5150954A (en) | 1976-05-06 |
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