DE1806194C3 - Process for the pressureless curing of ethylene polymers - Google Patents

Description

ι container fed from an extruder, and _; For this purpose, the rolled-out mass is granulated or pelletized at 12 and used in this as an external starting material. As

'Will be explained in detail, S rough filler can be mixed with the organosilane by adding the silane intimately to the filler - d then the pretreated filler is added to the -adischoperation, or else the and the organosilane are added separately to the w Mibcr, where then the treatment takes place. The mass is then a ouicucn Drablummantehingsmaschine 14 to-Είη metallic conductor 16 passed from a

18 through the extruder where the polymer is extruded and forms an insulation over the conductor.

When it exits the extruder, the isolated 119 passes through an elongated tube 20 which contains an “poor-transferring medium 22, for example an oil, and which is furthermore provided with suitable valves or drainage devices 23. The heat transfer medium is maintained at an elevated temperature sufficient to cause substantial hardening of the polymer in place. The temperature required depends primarily on such factors as the type of polymer compound, the heat transfer medium and the curing agent used. The length of the tube 20 and the flow rate through this tube are intended to allow sufficient residence time of the product 19 in the heat-transferring medium in order to bring about a substantial hardening of the polymer, and they can easily be determined by the person skilled in the art. The tube 20 is heated, for example, by an electrical heating coil (not shown) or by other suitable means. It has been shown, however, that a tubular device is a convenient and practical means of c use in the manufacture of wire and tubs, which requires little equipment and little heat-transferring medium

^The tube 20 ends in a housing 24, which is preferably in communication with the atmosphere via a flue pipe 26 provided with an exhaustor 28. A roller 30 is also located in the housing 24, and the cable is leached from the tube 20 via the roller into an elongated cooling tube 32 which is maintained at a sufficiently low temperature to cool the insulated conductor; in general, it is sufficient to to keep the cooling tube at room temperature and to rush air through the tube with the exhaustor 28 in countercurrent to the cable. If desired, other means of cooling the cable can of course also be used. For example, the tube can be provided with a cooling jacket and a coolant can be passed through this cooling jacket, or the cooling tubes can contain a liquid which is kept at the desired low temperature. Of course, a tub or a tank can also be used in place of the cooling tube 32. A collecting container 34 mounted in the pipe is used for any liquids that come from the cable and have been transported out of the tube 20 to drain. The product obtained is then on the Reel 36, which is provided with a guide mechanism 38 to ensure that the cable is rolled up evenly, is wound up. .

As has already been stated above, Wurü the cable exiting the extruder through a heat transfer medium which is kept at a sufficiently high temperature to achieve a It should be noted that the heat-transferring medium compared to the polymer in the must be essentially inert. For example, any number of heat transferring Materials can be used including organic liquids, gases, molten salts and salt solutions, and molten metal alloys. According to a preferred embodiment of the invention, a polyalkylene glycol is used which can be either water-soluble or water-insoluble and has a viscosity that 50 to 90,000 Saybolt Universal seconds at 38 ^ amounts to. Other suitable organic liquids are glycerine and its esters and propylene glycol and its esters. Suitable gaseous heat transfer materials are air, carbon dioxide and Nitrogen, which at the curing temperature is essentially free of water vapor and opposed to the polymer are practically inert. The gaseous warm transferring, carrying medium, which can be preheated preferably passed through the curing tube or chamber in countercurrent to the insulated conductor. and curing * is practically carried out at atmospheric pressure.

According to the invention, the hardenable mass contains an ethylene-containing polymer, hardening agent and a mineral filler which has been treated with an organosilane compound. Besides, certain additives are usually mixed together with the polymer mixture. This M "* £ hung additives can Antioxydant.en as P ^ol y ^{me" they "e. s} trimethyldihydroquinoline, a lubricant such as CaI-ciumstearat, Getting Connected to prevent ^{Zusa "me} ^ bens during processing, an incombustible agent, such as antimony oxide, and halides / to the flame resistance to enlarge an layers * such as polybutadiene, the Verntunnflzu and contain a small amount of pigment or dye, the mixing additives can vary considerably, and uses other than those mentioned above can also be used, depending on the properties desired in the end product

If desired, polyethylene can be used alone or in conjunction with one or more other polymers. However, this largely depends on the requirements placed on the end product. The component containing ethylene can be polyethylene which is mixed with other ™ y «™» £ copolymers of ethylene and other po ty ™ ™? ' hard materials is blended. Suitable copolymers of ethylene are Athylenpropylen-Mischpoly merisate, Äthylenpropylen-Dien-Terpolymensgejd

Ethylene vinyl acetate. The amount of in the copoly The ethylene used changes the E.gen TcSen of the end product and can therefore be varied to get the results you want ^ aim. A typical copolymer from AthyienJ "** ^ contains about 50 mole percent of each

And a copolymer of ethylene vinyl acetate contains depending on the desired properties of the

^ wa ^ Xliii'SiSUevnbli'teprözent'ethylene, and the remainder of the final product can be varied. The filler content

is ^ myiaicetait. 'is 25 to 60 percent by weight of the mass and

i) asί PÖlyfiäiylen or the copolymers of poly- preferably 30 to 50 percent by weight,

ättylen can with a chlorine-containing polymer, such as 5 The mineral filler is with an organic

"ChiörifrtiÄ polyethylene, chlorosulphonated polyethylene, preferably the alkylalkoxysilanes, in which the

ϊέίη ^ ΰΐκΓ ^ ^ yvinylcMbrid be blended around the alkyl group has at least 2 carbon atoms

Flarhm resistance of the mass to increase. It is treated on and the vinylalkoxysilanes. It was

known that the flame retardant properties surprisingly found that a mass that

the polyethylene masses by using a chlorine-io a mineral treated with an organosilane

containing polymers can be enlarged. The filler contained and according to the invention

Masses can contain up to about 1½ percent by weight of chlorine, the process had been hardened, a significantly larger

based on the total weight of all present ßere density (less porous) than the same

Polymers. A higher chlorine content can result in a mass that contained a filler that was not compatible with a

adversely affecting the mass by treating a porous organosilane compound. White

Froduct is formed. The chlorine-containing polymer was subsequently found that the invention with regard to

h Itiiν seen more expensive than the polyethylene, and therefore Hch of the mineral fillers is selective and that

it is advisable to use a low chlorine content, carbon black fillers that are pretreated in the same way and

which are just mixed in with a sufficient flame resistance result in a hardened product,

speed guaranteed, so that the hardened mass which is relatively porous and as an insulation material is not

the end product is suitable for the requirements set. It should be noted, however, that small amounts

Flicker resistance met. The tensile strength of the final carbon black can be added to the mass as a color pigment Product is generally increased by a can and that in such a case the soot in Proportion of the unchlorinated polymer or copolymer in an amount of 2 to 7 parts per 100 parts of the poly

elevated. However, at least a chlorine content of 25 mers is added. The filler is 0.15 to

2 percent by weight, based on all polymer components, 4 percent by weight of an organosilane and preferably

nents, used to treat the desired flame resistance 0.5 to 3 percent by weight. An over-

to give the product its ability to perform. The shot of the organosilane obviously acts as a soft

The proportions of the individual ingredients can thus be internal to the tensile strength and electrical strength

half of the set limits can be varied to reduce the properties of the hardened mass and

the mechanical required for an insulation compound continues to result in a porous product and from this

To meet properties and performance characteristics. Basically should be avoided. Suitable silanes

A suitable mineral filler, ethyl-triäthoxysilan, N-Hexyl-trimethoxysilan, is added to the insulation mass, which provides the mass with the necessary dodecyl-trimethoxysilane, a-methacryloxypropyltridigen strength, which is necessary for the processing of methoxysilane and amyl-triäthoxysilan as well the Vi-Kahels is necessary so that it is during the Vernylsilane. for example vinyl tri- (2-methoxyethoxy) processing retains its structure. With those in the silane, vinyl-trimethoxysilane and vinyl-triäthoxysilan. The mixing process is carried out in a temperature range around those generally used for polymer compounds, which is high enough to keep the mixture of fillers such as aluminum silicate, aluminum oxide, 40 sufficiently plastic for processing, calcium silicate, silicon dioxide, magnesium silicate, However, the titre is below the reaction temperature or the tandioxide and mixtures thereof. The filler decomposition temperature of the curing agent can be certain inert impurities, for example that the curing agent is retained during normal metal oxide, which up to 5 percent by weight of the mixing process does not yet decompose and can thus make up part of the filler. Such filling materials or initially hardening of the polyethylene are generally known and have been brought about on the market. The hardening agent used is easily available for the purpose. The type of filler used moderately oxide, an organic peroxide, such as a tertiary Perhängt largely on the desired properties, which by at least one structural unit of the final product from wad can be easily determined by those skilled qq. The titanium dioxide filler has in go I j

kenr drawing a particle size of 0.2 to qq q qq ς,

0.4 microns (the whole is the diameter) and a ■ 1

speafi χhs Ce * icht from 3.9 to 4.1. The other FuU- '·

materials are typically calcined to obtain ^

the moisture content is marked to less than 0.5 weight- $ 5 and that is at a low temperature

percent to err, and generally have decomposed above 135 ° C. The use of such

They have a particle size in the order of magnitude of peroxide hardening agent to effect a

2 microns mdiisei and a specific «weight netaag of polymers such as Poryätiiyleiiverbindongen,

W) 2.5 to 2.8. However, it is also applicable in the USA. Patents 3,079,370, 2,888,424,

a magnetic series filler with a leaflet 60 3 086 966 and 3 214 422 is described. The one on the mast

like structure, a particle size of no longer preferred and commonly used peroxide

Di-a-comyl peroxide is more than 6 microns and suitably more specific. Other breweries

brcueon from 18 to 20m * / g, which after the bare Hiatel border the tert. Diperoxides, BET gas adsorption method has been determined, such as 2, S-Dimetfayl-2,5- <t.-butlproxexane, 2> di-

end a specific gravity of 2.7 to 2.8. e _s metbyl-2Xt.-butylperoxy) -hexyne-3 and similar di-

The function of these fillers in polymeric isoloperoxy compounds.

tion masses is well known, and the amount of The proportion of peroxy curing agent used

The fillers incorporated in the mass can depend largely on the desired mechanical

Properties, such as tensile strength, in the cured product. A range of 0.5 to 10 parts by weight of peroxide per 100 parts of polymer will meet most requirements, and the usual proportion is on the order of 2 to 4 parts of peroxide. In a typical method in which a tertiary peroxide is used as curing agent, the mixing is carried out at a temperature of about 93-135 ⁰ C. If the mixing takes place at a much higher temperature, the peroxide decomposes and thereby causes premature curing of at least part of the polymer. As a result, the mass is difficult to process and the end product has an irregular or rough surface.

Aside from the fact that economic advantages are achieved by avoiding high pressure during curing, another significant advantage is that the present invention makes it possible to manufacture cables with a sodium conductor insulated by a chemically crosslinked polyolefin. A cable of this type and the manufacturing process are described and claimed in our own FR-PS 1 561 864. It is readily apparent that such a cable cannot be cured under steam pressure, since working with sodium in an aqueous or steam-containing atmosphere is extremely dangerous. In addition, sodium is liquid at the temperatures used to manufacture and cure the cable, and since the insulation layer is in the plastic state when it exits the extruder and enters the curing oven, it would be in the curing oven used high pressure to compress the walls of the cable and squeeze the sodium out of its insulation jacket. However, by avoiding an aqueous environment in the process of the present invention and performing curing in the absence of elevated pressure, such an insulated sodium cable can be produced.
According to a further embodiment of the present invention, the hardenable composition can be subjected to a vacuum treatment prior to the hardening process, e.g. B. the extruder can be provided with a venting device and vacuum to the

ίο Cylinder liner of the extruder should be put on, if the mass becomes liquid or is plasticized and pressed by the cylinder screw through the cylinder liner will. If necessary, the mixture can also be supplied to the extruder from a vacuum unit Reservoir are supplied. The execution of this operation under vacuum has proven to be special proven advantageous to obtain a relatively dense product.

The following examples serve to further

ao explanation of the invention.

Examples 1 to 15

In Examples 1 to 15, the compositions were prepared according to the recipes listed in Table I by conventional mixing methods. The amounts listed in the table represent parts by weight for each component. The masses were then ^{shaped into sheets of 29 cm 2} with a thickness of about 0.1905 cm. The plates were then cured by 2 minuter immersion in polyalkylene glycol having Einei temperature of 200 ⁰ C. The polyalkylene glycol had a viscosity in Saybolt-Universal seconds of 300. The hardened products were tested for their degree of hardening by toluene extraction. A 2 g sample was tested in accordance with ASTM D-29? Extracted for 16 hours by boiling toluene.

Table I Recipes and toluene extracts

example

2 3 4th 5 6th 100 100 100 100 100 1
3.5 1
3.5 1
3.5 1
3.5 1.75
3.55 so 50 50 50 1.5 1.5 1.5 U HS
3.45 6.8 11.9 11.4 14th

Polyethylene

Ethylene vinyl acetate copolymer

(6 percent by weight vinyl acetate)

Polymerized Trimethyldihydrocninoline

( Antioxidant)

Γ. i-a-cumyl peroxide (90% active)

2 5-Dimethyl-2,5-dHt.-butyi-peroxy) faexane

(50% active)

2,5 "dimethyl-2,5-di- (t-butylperoxyHiexin-3

(90% active)

Aluminum silicate (calcined) Magnesium silicate Hydrated aluminum silicate

Precipitated hydrated silica. Aluminum silicate, pretreated with

Vinyl silane Titanium dioxide (pyrolytic process) Vinyl-tris- (2-metnoxy-fithoxy-süan) Vinyltriethoxysilane Ethyltriäthoxysüan N-hexyl-trimethoxysilane Dodecyitrimethoxyeilane

α-methacryloxypropyltrimethoxysilane

Amykriathoxyeilan Toluene extract (% by mass)

100 100

SO

509638;

Table I.

10

Recipes and toluene extracts (continued)

8th 9 10 Example
11th el
12th 13th 14th 100 100 100 100 100 100 100 1 1 1
3.5 1
3.5 1
3.5 1
3.5 1
3.5 6.77 3.34 50 50 50 50 50 50 50 1.5 i, 5 1.5 1.5 1.5 1.5 1.5 13.0 15.4 10.5 12.9 14.1 12.4 13th

Polyethylene Ethylene vinyl acetate copolymer

(6 percent by weight vinyl acetate)

Polymerized trimethyldihydroquinoline

(Antioxidant)

Di-a-cumyl peroxide (90% active)

2,5-dimethyl-2,5-di- (t-butyl-peroxy) -hexane

(50% active)

2,5-dimethyl-2,5-di- (t-butylperoxy) -hexyne-3

(90% active)

Aluminum silicate (calcined) Magncsiuinsilicate Hydrated aluminum silicate

Precipitated hydrated silica. Aluminum silicate, pretreated with

Vmylsilane

Titanium dioxide (pyrolytic process) Vinyl tris (2-methoxy-ethoxy-silane) Vinylträthoysilan Ethyltiiäth'ysilane N-hexyl-t m thoxysilane Dodeyltrimethoxysilane

«-More loxypropyltrimethoxysilane

Amy triä h ixysilan Toluene extract (% by mass)

100

In Example 7, the mineral filler was pretreated with a vinylsilane compound and the pretreated filler was added to the Banbury mixing operation been. Likewise, in Example 7, the sample was initially subjected to a one-hour vacuum treatment subjected to about 711 mm Hg and then cured as described above. In all of the other examples above, the filler and the Organosilane compound added separately to the mixing operation.

The toluene extracts show that the polymer compared to conventional steam curing processes was cured to a relatively high degree. These conventional steam curing processes gave toluene extracts in the range of about 6 to 15 ".

All samples were visually checked for porosity, and they were found to have little or no porosity and therefore to be insulation were useful for wires and cables. This property is clear from FIGS. 2 and 3 can be seen, the Present microphotographs of Examples 1 and 2. To better explain the problem of porosity and also better expressing the fact that the invention is selective for the mineral fillers treated and not for carbon black fillers, three were made Masses mixed together according to the following recipes:

Table II 45 16 example
17th 18th Polyethylene ...
It polymerizes
50 trimethyl dihydro
quinoline
Soot .. 100
1
50
3.5
11.6 100
1
40
2.2
24.6 100
2
40
1.2
23.1 Aluminum silicate
Di-11-cumyl peroxide ...
55 vinyltri- (2-methoxy-
ethoxy> silane
Toluene extract (% of
Link) .

The sample plates of these masses are in gjeicfes Way as in the preceding examples in the ge called hardened polyalkylene glycol. Example 16 is a control sample for mineral fillers that «c & t m * Organosilane were treated. Example 17 is eh *

Control sample for carbon black which had been treated with the organosilane, and Example 18 && Md for a pretreated carbon black. The micrographs of Figs. 4, 5 and 6. The description of the case

play 16, 17 and 18, show that these samples are relatively porous and therefore used as insulation for wires and cables were not suitable.

Example 19

A Äthylenpropylencopolymeres with about 40 to percent by weight of ethylene (about 50 mole percent ethylene) and 40-Mooney ML value at 100 ⁰ C was gernäß mixed together the following recipe in a Banbury mixer:

Ethylene propylene copolymer 100

Polymerized trimethyldihydro-

quinoline 2

Zinc oxide 3

PbO ₈ 2

Buton 150 (Coagenz) 5

Aluminum silicate 100

Flexon 865 (processing aid) .. 5

Vinyl tri- (2-methoxy-ethoxysilane) 1.5

Di-x-cumyl peroxide (90% active) 3

Toluene extract (% of compound) 10.6

A plate made from this mass was cured as in the previous examples, and the cured Product turned out to be relatively tight and therefore suitable for use as an insulation material. This works out also clearly from FIG. 7 emerges.

Example 20

An insulation compound was made according to the following recipe using conventional mixing methods made in a Banbury mixer:

Ethylene vinyl acetate copolymer 91.6

Chlorinated polyethylene

(43 ^l / ₂ t 2 ° / _o Cl ₂₎ 8.4

Calcium stearate 0.9

Magnesium silicate 72.5

Vinyltri- (2-methoxy-ethoxy) -silane .... 0.9

Dibasic lead phthalate 2.8

Thermax black (color pigment) 3.7

Polymerized trimethyldihydro-

quinoline 1.5

Di- \ -cumyl peroxide (90% active) 4.5

Toluene extract (% of compound) ... 11.2

The admixed mass has a wall thickness of 0.397 mm to a twisted with about 1 mm in diameter and pressed in the above-described polyalkylene glycol liquid ness for 1.5 minutes at about 190 ⁰ C cured. The hardened insulation compound turned out to be relatively dense (non-porous) and therefore suitable as insulation.

Example 21

Using a conventional mixing technique, an insulation compound was made in a Banbury mixer according to the following recipe. The quantities given are percentages by weight:

Polyethylene 61.80

Aluminum silicate 30.90

Vinyl tri- (2-methoxy-ethoxy) -silane 0.93

Di-uc-cumyl peroxide (90% active) 2.20

Carbon black (pigment) 3.09

Polymerized trimethyldihydro-

quinoline 1.08

The mass was at about 132 ° C at one rate extruded from about 0.9 to 1.5 m per minute while at the same time the extruded tube was filled with liquid sodium. The extruded cable had an outside diameter of about 1.97 cm and a wall thickness of the insulation of about 0.44 cm.

After exiting the extruder it was

ao cable passed through a 9 m long tube and heated ^{to a temperature between about 163 and 204 0 C by means of an electrical heating coil.} The tube was filled with a polyalkylene glycol that had a viscosity of 300 or 280 Sebolt Universal seconds.

The cable was then passed through an air-cooled tube approximately 9 m in length to feed the cable cool and solidify the sodium.

Examples 22 to 24

Masses were produced according to the recipe described in Example 1. In one through one electric Plate samples were distributed to a tube heated by a coil and provided with an opening in the bottom. Gas was introduced into this tube, kept at 200 ° C, and the samples were placed in the tube Stored for 4 minutes. The cured samples were found to be tight, and those as a heat exchange medium The gases used and the degree of hardening were as follows:

example gas Toluene extract
(° / o of the mass) 22nd
23
24 air
Carbon dioxide
nitrogen 22.5
16.9
11.8

The cured products were relatively dense, which is clear from Figs. 8, 9 and 10 of Examples 22, 23 and 24, respectively.

From the above description and the examples it can be seen that according to the present Invention obtained a relatively dense product while avoiding a high pressure curing system which is particularly useful as an insulation material for wires and cables.

For this purpose 2 sheets of drawings

Claims (7)

1 2 Apparative utilization and monitoring expensive and patent claims: hatüis Particular Wasicht of the application of 1. Process saw pressureless hardening of ethy- steam the further disadvantage that τ.Β .Kabel with fcB-Pofefmematen for the production of porenfreiii sodium atom because of its reactivity not molded and Kabeläberzaigen, thereby S can be hardened, characterized in that from the invention was therefore the basis of the task, a a) customary ethylene homo- or mixed-poly process for the unpressurized curing of ethylene polymers or mixtures of these polymers to create pore-free moldings sate with other polymers, which leads to the mass and cable coatings. The one with one optionally impart flame resistance, w difficulties involved in the process b) 0.5 to 10 parts by weight, based on 100 Ge Avoid the in the to be vulcanized by weight of the polymer, the peroxides and the mixture contained in the air and moisture c) 25 to 60 percent by weight, based on the porosity, result from the publication Mass, a mineral aid treated with 0.15 to 4 percent by weight of the Bayer works "Vulcanization and Vulkamsationseines OrganosUans", in which this problem in particular The filler mentioned on pages 78 and 79 is mentioned. The in this publication a homogeneous mass is produced and this solution called solution consists in the use of a Mass at atmospheric pressure or less by means of a desiccant. However, such desiccants are in essentially inert, non-aqueous, heat-insulating cable coatings are not always desirable, The transferring medium is passed through, the further object of the invention was therefore based on a method for unpressurized hardening, which would be sufficient for hardening the mass high temperature is maintained. Production of pore-free moldings even without 2. The method according to claim 1, characterized in creating a desiccant label. According to the present invention, the polyethylene, an ethylene-propylene copolymer as named objects are achieved in that in a process or an ethylene vinyl acetate copolymer. drive out of the type mentioned above 3. The method according to claim 1 or 2, characterized in a) conventional ethylene homopolymers or copolymers that the mineral filler seeds or mixtures of these polymers with Aluminum silicate, calcium silicate, magnesium silicate - other polymers which give the compound, silicon dioxide, aluminum oxide or titanium - if flame resistance, dioxide is. b) 0.5 to 10 parts by weight, based on 100 parts 4. The method according to any one of claims 1 to 3, parts by weight polymer, conventional peroxides and characterized in that the organositan c) 25 to 60 percent by weight, based on the mass, The compound is an alkylalkoxysilane wherein the mineral filler treated with 0.15 to 4 percent by weight of an organo-alkyl group at least 2 carbon atoms on the sulfate has, or is a vinylalkoxysilane. a homogeneous mass is produced and this mass 5. The method according to any one of the preceding at most atmospheric pressure by an essential-claims, characterized in that the borrowed inert, non-aqueous, heat-transferring heat transfer medium is passed through a polyalkylene glycol medium on a for the kol is. 40 hardening of the mass at a sufficiently high temperature 6. The method according to one of the preceding is held. Claims, characterized in that the hard With this inventive method for bare mass before the hardening process a vacuum hardening is possible, even without use is subjected to kuum treatment. a desiccant at atmospheric pressure or 7. Application of the method according to claim 1 45 including practically pore-free molded bodies or cables 6 to produce an insulated electrical coating. The cable covers show the Cable, characterized in that the hardenable mass around an electrical conductor, which is also required for high voltage loads, has impact strength. Based on the state of the art technology and is hardened. nik was not to be expected that with such a 50-fold process pressureless pore-free moldings and Cable covers can be made. The present invention relates to a method. The invention is hereinafter referred to for the pressureless curing of ethylene polymers explained in more detail on the drawing, which is advantageous for the production of pore-free moldings and adhesive embodiments of the cable coverings according to the invention. 55 driving result The designations used For many applications, especially for insulation "wire" and "cable" are synonymous with insulated electrical wires and cables, the absence of pores in the tric conductor has been used. In detail shows hardened insulating coating of extraordinary- F i g. 1 is a schematic view of an apparatus Licher importance for the required breakdown to carry out the method according to the invention strength. 60 in elevation and To produce such pore-free molded bodies F i g. 2 to 10 microphotographs (with 7 fold It has been customary up to now, with relatively high magnification) of typical cross-sections of the inventions pressures (about 14 to 17.5 kg / cm ² or more) under the hardened masses according to the invention, which harden according to the application of steam. The examples below have also been produced, script "Modem Plastics", February 1967, pp. 91 to 93 65 The insulation compound is denoted in a Banbury mixer with 10 and 169 to 172 is not otherwise mixed in this regard removed. Such hardening at relatively then reaches a mill 11, where it is rolled out for the further high pressure, however, because of the processing required for this. The mass will then