Method for producing a syntactically foamed polymer composition, preferably a pressure-sensitive adhesive mass

p0001The invention describes methods for producing a syntactic foamed polymer composition, preferably a pressure sensitive adhesive composition, wherein<ol><li>a) at least the majority of the completed foam cavities is achieved by the introduction of expandable microballoons in a matrix material and subsequent mixing and</li><li>b) the expansion of the expandable microballoons to their introduction into the matrix material,</li><li>c) wherein the temperature distribution in the mixing unit (1) is inhomogeneous in a sectional plane transverse to the conveying direction of this unit (1).</li></ol>

p0002The invention also describes two devices for carrying out the above method, an extrudate and a self-adhesive tape, which is prepared according to the abovementioned method.

p0003The word "syntax" means that at least the periphery distant foam cavities are completely surrounded by a matrix material and thereby completed.

p0004With expandable microballoons foamed self-adhesive compositions are known. Opposite open cell foamed self-adhesives they reach their closed cells a better seal against dust and liquids. Compared to non-cellular self-adhesive compositions, they adapt better to the roughness of the substrate to be bonded. Opposite with glass bubbles foamed self-adhesives are they malleable and same thermal expansion differences between different bonded materials in fluctuating temperatures and better dampen and isolate vibrations better. How thick the shell (= shell) is the micro balloons and from which the thermoplastic polymer it consists, just affects the mechanical properties of the foam such as the initial diameter (= unexpanded diameter) of the microballoons and the kind of which is arranged in the interior of the blowing agent. These variables also affect the expansion starting temperature, the rate of expansion, the maximum expansion capability and robustness of the microballoons.

p0005A variety of expandable microballoon types can be bought; preferably unexpanded types are used for the invention, because they have a greater expansion capacity than the already pre-expanded types. In the class of the non-expanded, there are many types of different manufacturers; they differ substantially in diameter (6 to 9 microns for the smallest types of Expancel, namely 461 DU 20, and 28 to 38 microns in the largest of Expancel, namely 920-, 930-, and 951 DU 120) and their needed for expansion starting temperature (75 to 220 ° C). An example of commercially available microballoons are the Expancel^® DU-types (DU = dry unexpanded) from Akzo Nobel.

p0006The word "uniform" (= "homogeneous") we use in this application in the sense that the specific mass of taken out of the product specimen - whose edge length of course much larger (ie about at least 30 times as large) must be less than the diameter of the largest expandable microballoons therein - is convenient regardless of is taken at which places the product of these specimens. This word does not mean or about that all expanded microballoons should be the same size; they could not at all, because even their precursors, the unexpanded microballoons are produced in a statistical method, thus have a certain margin of individual micro balloon to individual microballoon both in diameter and in its wall thickness.

p0007The preparation of expandable microballoons is described fundamentally in <patcit id="pcit0001" dnum="US3615972A"><text>US Patent 3,615,972</text></patcit> from Dow.

p0008The <patcit id="pcit0002" dnum="DE2105877C"><text>DE 21 05 877 C</text></patcit> discloses a self-adhesive tape with a carrier, which is coated (also referred to as "pressure-sensitive adhesive") on at least one side with a microcellular adhesive composition. This adhesive layer containing a nucleating agent, wherein the cells of the adhesive layer and are distributed closed "uniformly" in the adhesive layer.

p0009The <patcit id="pcit0003" dnum="US6103152A"><text>U.S. Patents 6,103,152</text></patcit> and <patcit id="pcit0004" dnum="US6797371B"><text>6,797,371</text></patcit>Which correspond to <patcit id="pcit0005" dnum="EP1102809B1"><text>EP 1102809 B1</text></patcit>, Teach a method for producing polymer foam with expandable microballoons. In a public declaration of invalidity against the German part of the European patent, the patentee argued that a Schäumungsbeginn before leaving the nozzle - being here out of context can be seen the formative nozzle is meant the end of a second extruder - actually a Schäumungsbeginn in the nozzle meant be. The is the German<nplcit id="ncit0001" npl-type="s"><text> Bundesgerichtshof in its decision "polymer foam" of July 17, 2012 (document number: XZR 117/11, paragraph 31, last sentence</text></nplcit>) Followed.

p0010The <patcit id="pcit0006" dnum="EP0257984A1"><text>EP 0257984 A1</text></patcit> describes self-adhesive tapes, the at least one side having a foamed adhesive layer containing microballoons. According to page 3, lines 38 to 41, the microballoons may be incorporated in their unexpanded state in the adhesive and expanded by subsequent heating, or - are only expanded and then mixed into the adhesive - preferably.

p0011As less relevant appear the other writings <patcit id="pcit0007" dnum="DE3537433A1"><text>DE 35 37 433 A1</text></patcit>. <patcit id="pcit0008" dnum="WO9531225A1"><text>WO 95/31225 A1</text></patcit>. <patcit id="pcit0009" dnum="WO9532851A1"><text>WO 95/32851 A1</text></patcit>. <patcit id="pcit0010" dnum="EP0693097A1"><text>EP 0693097 A1</text></patcit>. <patcit id="pcit0011" dnum="WO9818878A1"><text>WO 98/18878 A1</text></patcit> and <patcit id="pcit0012" dnum="DE19730854A1"><text>DE 197 30 854 A1</text></patcit>,

p0012The <patcit id="pcit0013" dnum="DE102008004388A1"><text>DE 10 2008 004 388 A1</text></patcit> teaches a method for producing a non-cellular self-adhesive composition with natural rubber as the base polymer. In this connection, teach the Examples 5 and 6 on pages 23 and 24, a manufacturing method using, inter alia, a planetary roller extruder. If the local "heat zones" as the two radially outer ring gears of a two-shot planetary roller extruder be interpreted, is proposed there that in two shots, the ring gear is heated to 50 ° C, while the sun (= central spindle) tempered only at 10 ° C is.

p0013The invention is based on the object, the homogeneity of the mixture of micro balloons and matrix mixture at least in comparison to products previously known - of which in accordance <patcit id="pcit0014" dnum="EP1102809B1"><text>EP 1102809 B1</text></patcit> produced as the closest appear-maintain, in a process which is less thermally and mechanically loaded the matrix polymers. The searched mixing method is not larger and preferably further reduce the rate of destroyed microballoons. Preferably should be reduced already the foamed extrudate surface roughness.

p0014To his surprise, the inventor - by going about phenomena that were initially held for measurement error - found that the homogeneous distribution of microballoons particularly well and efficiently achieved if the temperature distribution in the mixing unit is inhomogeneous transversely to the direction of this unit. In particular, should according to the invention<ul><li>d) in a section transverse to the direction of the mixing unit (1) a first mixing zone (2) limiting surface (3) of the mixing unit (1) be so high temperature that the polymer composition containing the microballoons, insofar as it is in contact with this first limiting surface (3) device, a temperature (T_e) Is achieved, which is sufficient for the start and progress of the expansion,</li><li>is e) while in the same section transversely to the direction of the mixing unit (1) a second mixing zone (2) limiting surface (4) of the mixing unit (1) temperature so low polymer composition that the microballoons containing, so far as it with contact this second delimiting surface (4) device, no temperature (T_e) Is achieved, which is sufficient for the start and progress of the expansion.</li></ul>

p0015In a single screw as mixing unit it is advisable to provide the temperature difference between the inventive screw and barrel (= barrel). If the matrix polymer base - possibly in addition to a resin klebrigkeitssteigernden - acrylates and / or methacrylates are used, it is advisable to orient the temperature difference around so that I: the screw is cooler than the casing (= barrel), preferably at least 50 ° C, particularly preferably by an amount of between 65 ° C and 90 ° C.

p0016If, however, as the matrix base polymer - are used if necessary in addition to a klebrigkeitssteigernden resin polyethylene and / or polypropylene and / or polyethylene vinyl acetate and / or Polypropylenvinylacetat and / or copolymers of some or all of the monomers mentioned, it is recommended that reversed to orient the temperature difference around ie so that II: the worm is hotter than the casing (= barrel); the preferred amount of the temperature difference remains the same, namely, at least 50 ° C, more preferably between 65 ° C and 90 ° C.

p0017In a twin-screw extruder as MIXING aggregate are various options for displaying the gewünschtermaßen inhomogeneous temperature field in a plane transverse to the conveying direction, namely, in order to differentiate only between hot and cold: <ul><li>III: a worm cold, the hot other housing cold,</li><li>IV: a worm cold, the hot other housing Root</li><li>V: both worm cold, housing Root</li><li>VI: both snails hot housing cold.</li></ul>

p0018With "hot" the containing a contacting gone slightly with this component, expandable microballoons ground for expansion in each case is such a component temperature meant sufficiently heated, whereas "cold" such a component temperature means that in contact gone slightly with this component, expandable microballoons containing compound can be too cold for expansion.

p0019The possibility V is preferred that as the matrix base polymer - and / or methacrylates are used Acrylate - if necessary in addition to a klebrigkeitssteigernden resin. Also in this case, the preferred amount of the temperature difference is at least 50 ° C, particularly preferably between 65 ° C and 90 ° C.

p0020VI The possibility is, however, preferred when the matrix base polymer - are used polyethylene and / or polypropylene and / or polyethylene vinyl acetate and / or Polypropylenvinylacetat and / or copolymers of some or all of the monomers mentioned - if necessary in addition to a klebrigkeitssteigernden resin. Also in this case, the preferred amount of the temperature difference is at least 50 ° C, particularly preferably between 65 ° C and 90 ° C.

p0021This variety of orientations avoids both cants in the bearings of the screw or screws and blockages in the feed tube.

p0022In a planetary roller extruder - which is preferred for the industrial exploitation of the invention, firstly because here in a compact configuration, yet large available for temperature control surface the desired temperature inhomogeneity can be reproducibly adjusted in a particularly wide range, and secondly because the ringfömige structure of this device type, despite the inhomogeneous temperature distribution avoids that occur due to different thermal expansions canting in camps - are many different orientations of temperature differences can be generated. The construction of a planetary roller extruder is particularly simple if an active temperature control ( "tempering" is understood in this application as a generic term of "heating" and "cooling") of the planet gears is omitted. Although This eliminates many possibilities of orientation, but the following two remain:<ul><li>VII: Cool sun and hot gear or</li><li>VIII: Hot sun and cool gear.</li></ul>

p0023Similar to the way I the screw extruder and the possibility V the twin screw extruder is the planetary roller extruder, the possibility VII preferred if the matrix base polymer - are used acrylates and / or methacrylates - possibly next to a klebrigkeitssteigernden resin. Also in this case, the preferred amount of the temperature difference is at least 50 ° C, particularly preferably between 65 ° C and 90 ° C.

p0024And analogous to the possibility II the single screw extruder and the possibility VI, the double-screw extruder III the possibility VIII is the planetary roller extruder is preferred if as the matrix base polymer - if necessary in addition to a klebrigkeitssteigernden resin - polyethylene and / or polypropylene and / or polyethylene vinyl acetate and / or Polypropylenvinylacetat and / or copolymers from some or all uses of the monomers mentioned. Also in this case, the preferred amount of the temperature difference is at least 50 ° C, particularly preferably between 65 ° C and 90 ° C.

p0025The inventor has found that the possibility VII permits a substantial expansion of the microballoons in the planetary roller extruder already during mixing. Such early expansion was previously thought to be impossible, because too large an amount of destroyed microballoons was feared their shell thickness is finally in the expanded state only at about 0.02 microns. For this purpose, ie the internally toothed ring gear of the planetary roller extruder is as high temperature, polymer composition that the microballoons containing, insofar as it comes into contact with this ring, a temperature is reached which is sufficient to start and progress of the expansion. Meanwhile, to the externally toothed sun be tempered so low that the polymer composition in the microballoons containing, insofar as it comes into contact with this sun, no temperature is reached which is sufficient to start or progress of the expansion.

p0026Unless later for other purposes - whether for expelling residual gases such as air, residual solvent vapor, residual monomers, water vapor - the temperature of the mass as high and must be low on their oppressive pressure that the possibility for further expansion of the microballoons is inevitable may be selected to the process conditions during the mixing in the planetary roller extruder (particular case temperature, central spindle temperature, speed, degree of filling and pressure) that the means technically meaningful expansion capability - which is given based on the achievement of about ¾ the volume that reaches a maximum among the finest laboratory conditions could - is already fully used until the completion of mixing.

p0027In keeping with the established micro balloon type with their foaming can therefore be applied during mixing such a temperature profile in the radial and longitudinal direction that foaming already starts during mixing at least. The inventor explains the amazing effect - namely that the microballoons its expansion beginning so without prejudice to survive even during mixing - so that there is a particularly gentle conformity between the planetary roller and the ring. Compared to two meshing external gears submerge the teeth of the planetary roller gradual and gentle - in particular with gentler Scherungsspitzen - in the tooth spaces of the ring gear and tighten Also just gently back behind the point of deepest immersion. The same applies analogously to the teeth of the ring gear when immersed in and running out of the tooth gaps of the planet rollers.

p0028The inventors further hypothesized that the coarser combing the planet rollers with Sonnenrade hardly affected the microballoons, because in this contact zone due to there cooler temperatures to mixing mass - at least this is true of the date of this tried out acrylate and acrylate-methacrylate PSAs - is less adhesive happy and therefore stays on the premises less mass. Incidentally, even this contact on the amount of shear in lace making can not be compared with a co-rotating twin screw extruder but only with - apart from the PVC processing forth unusual - opposite, ie in radial section meshing and not seemingly slipping, twin-screw extruder. The the opposite extruder reputed tendency to clog is not observed at the planetary roller extruder - the inventors suspected: because of the lack of rigid containment of planetary roller and the sun roller - and also the commonly lamented lower mixing effect occurs in conjunction with the inhomogeneous temperature control according to the invention in a plane transverse to the direction of mixing unit not on.

p0029The scoring facilitating the achievement of a homogeneous mixture is particularly apparent when the temperature difference between the hotter internal gear and the cooler sun is at least 50 ° C. Particularly preferred is a temperature difference between 65 ° C and 90 ° C, since then the expansion will start already mastered especially safe during mixing. Even greater temperature differences turn out, however as for the effect to be achieved superfluous and only put an unnecessary expense for unnecessarily intense heating and unnecessarily intense above all cooling. The invention allows the couple and accept additional expenses for heating and cooling a particularly high homogeneity of the mixture and in preferred embodiment of the invention a particularly early start of the expansion with particularly accurate control of the degree of expansion and a particularly low rate of destroyed microballoons. The earlier start of the expansion also allows an earlier completion of the expansion; This has not only a cost advantage but also allows a cooler passing the shaping extrusion die with the additional advantages of lower dimensional tolerances in the finished product and smoother surface. Even without additional smoothing measures -As about subsequent lamination with a highly smooth liner and / or calendering, possibly only after the liner job -. Roughness be achieved below 12 microns on extrudate with special care down to 5 microns.

p0030This facilitated and improved by the temperature inhomogeneity inventive mixing not only protects the microballoons but - as intended - the matrix polymers by overall lower mechanical load and lower temperature stress. Thus, the polymer degradation remains low. The cost advantage by accelerating Beendbarkeit mixing and expanding and the quality benefits achieved outweigh the cost disadvantage through higher heating and cooling costs.

p0031The micro balloons surrounding the product according to the invention the matrix comprises essentially polymers. If the matrix is ​​to be self-adhesive, it preferably contains acrylates and / or methacrylates and / or polyolefins and / or natural rubber and / or styrene-butadiene rubber, preferably also one or more klebrigkeitsfördernde resins. Also the use of thermoplastic elastomers such as styrenic block copolymers - for example, styrene-isoprene-styrene (SIS) - and styrene-butadiene-styrene (SBS) grades - is possible.

p0032As klebrigkeitsfördernde resins are oligomeric and low-polymeric compounds in question having a number average molecular weight M_n up to 5000 g / mol. In question are particularly pinene, indene resins and rosins, their disproportionated, hydrogenated, polymerized and esterified derivatives and salts, the aliphatic and aromatic hydrocarbon resins, terpene resins and terpene-phenolic resins, and also C5, C9 and other hydrocarbon resins, individually or in combination , Particularly advantageously, all soluble in the polymer composition resins can be employed as all aliphatic, aromatic, alkylaromatic hydrocarbon resins, and hydrocarbon resins based on pure monomers, hydrogenated hydrocarbon resins, functional hydrocarbon resins and natural resins. Preferred terpene-phenolic resins are Dertophene T105 and Dertophene T110, a preferred hydrogenated rosin derivative is Foral 85. The resin content is in view of the attainable shear stability times as low as possible and in consideration of the tack required for the application (= tack) and vibration damping as high as necessary metered.

p0033Furthermore, plasticizers can be added such as low molecular weight polyacrylates, polymethacrylates, phthalates and polyphosphates to further increase the deformability, impact resistance and vibration damping capacity, often accompanied by a small increase in tack.

p0034In addition, a crosslinking of the matrix material is desirable for most applications. Even if such a network is advantageously carried out only at the end of the process, it must nevertheless be considered in the selection of the materials used at the beginning. Thus, the addition of a crosslinking agent such as sulfur or peroxide with the use of natural, isoprene or SBR rubber may be useful and / or when using other polymers of the installation - preferably already in the monomers used for the polymer production - such functional groups that together later can be networked. eligible, particularly olefinically unsaturated monomers having functional groups which can react with epoxide groups. are preferred for this purpose monomers containing functional groups from the following classes: hydroxy, carboxy, sulfonic acid, phosphonic acid, acid anhydrides, epoxides and amines. Particularly preferred examples of such monomers are acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, β-acryloyloxypropionic acid, trichloroacrylic acid, vinyl acetic acid, vinylphosphonic acid, Itasconsäure, maleic anhydride, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 6-hydroxyhexyl methacrylate, allyl alcohol , glycidyl acrylate and glycidyl methacrylate.

p0035As is well known, crosslinking reactions can be initiated by supplying energy, namely by UV radiation, electron radiation or heating. In keeping with the desired type of energy that be blended into the matrix crosslinking initiators are selected. When the crosslinking reaction is triggered thermally - as is preferred for the production of such products in which inked and therefore little or almost not at all transparent materials are to be processed or where layer thicknesses are to be produced in excess of about 160 microns - then should preferably the micro-balloon type used, the temperature profile and the site of addition of the initiator to be coordinated so that the network is not too far off the Gestaltgebung - they now be done in a form (= mold), a calender and / or an extrusion die - begins. As heat-activatable crosslinkers useful in the most preferred acrylates and methacrylates in particular isocyanates and epoxy compounds.

p0036Also, accelerators and / or retarders of the crosslinking reaction may be appropriately added, retarders in particular if the crosslinker is added to minimize the time and apparatus mixing effort at the beginning of the extruder, thereby hinnehmend that it in the radially outer region of the planetary roller extruder preferably used already during mixing is exposed to temperatures that allow the networking already begin. Alternatively, or in addition to the use of retarders of the installation of a blocking or steric hindrance in crosslinking isocyanate comes into question, for. Example, by alcohols, phenol derivatives or amines. Preferably - especially when a certain yellowing tendency does not interfere in the to-use application - a little more delay operated, as necessary for the purpose described above, to this surplus antagonistic slightly crosslinking accelerators - such as amines - to put in the mixture over can. As a rule, then gives a lower sensitivity of the temporal course of crosslinking compared to never quite unavoidable variations in the procedure and thus even smaller variations in product quality.

p0037When the planetary roller extruder is divided into several sections (= modules) and the crosslinking agent must be activated thermally and it is sufficiently distributed homogeneously in a short mixing path, then, however, the addition of the crosslinking agent in one of the later shots of the planetary roller extruder, or even in a downstream further extruder is preferred because as the particularly expedient for mixing and foaming process management needs less consideration to the crosslinkers and the taking by its too early and / or too heavy crosslinking with concomitant increase in viscosity.

p0038Regarding their design of each ring gear and in meshing planetary roller provides each shot a mehrschüssigen planetary roller extruder from as an independent (einschüssiger) planetary roller extruder; but the different shots by pulling a single continuous central spindle. In contrast to four successively arranged einschüssigen planetary roller extruders, where an engine and a transmission is required for each of the four central spindles requires a vierschüssiger planetary roller extruder only one motor and only one transmission. Although this must be correspondingly larger dimensions, performs the one stronger drive to a better efficiency than four weaker drives, implies a lower risk of failure and minor maintenance costs.

p0039Preferably contains the polymer foam to at least 25 wt .-%, based on the total weight of the polymer foam, an acrylic polymer - whether it is a polyacrylate or polymethacrylate or poly (acrylate-co-methacrylate) or a copolymer - which can be attributed to the following monomer composition can:<ol><li>(A) acrylic acid ester and / or methacrylic acid ester of the following formula         CH₂ = C (R^I) (COOR^II) where R^I = H or CH₃ and R^II an alkyl radical having 4 to 14 C-atoms,</li><li>(B), in minor amounts of olefinically unsaturated monomers containing functional groups having a reactivity with the crosslinker or a part of the crosslinker, such as two paragraphs enumerated previously detailed</li><li>(C) optional - in smaller amounts - other acrylates and / or methacrylates (a) and / or</li><li>(D) optionally further monomers which are copolymerizable olefinically unsaturated, and with the (a) component.</li></ol>

p0040The words "in small quantities" means doses at which the proportion by weight of the dosed component is less than a quarter that of the component (a).

p0041The compounds of group (a) are referred to as "acrylic monomers" in this application. Preferably such acrylic monomers are used whose alkyl groups contain 4-9 carbon atoms. Examples of such monomers are n-butyl acrylate, n-butyl methacrylate, n-pentyl, n-pentyl, n-amyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, n-heptyl, n-octyl acrylate, n-octyl, n-nonyl acrylate, n -Nonylmethacrylat, isobutyl acrylate, isobutyl methacrylate, isooctyl acrylate, isooctyl methacrylate, and the branched isomers thereof such as 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate.

p0042to the group (a) further include dodecyl methacrylate, lauryl acrylate, n-undecyl, n-tridecyl acrylate, sec-butyl acrylate, tert-butyl acrylate, isodecyl acrylate ,; Also consider these monomers to Copolymeraufbau in question.

p0043For polymers that contain the component (c) and / or (d), all vinylically functionalized compounds can be used in principle, which are equipped with the component (a) and / or the component (b) copolymerizable. Preferably, these monomers are also used for adjusting the properties of the resulting polymer foam. Examples are the following monomers for component (c) may be mentioned:<ul><li>Methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, isobornyl acrylate, isobornyl methacrylate, t-butylphenyl, t-butylphenyl methacrylate, stearyl acrylate, behenyl acrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, Phenoxyethylacrlylat, phenoxyethyl methacrylate, 2-butoxyethyl, 2-butoxy ethyl acrylate, 3,3,5-trimethylcyclohexylacrylate, 3,5-dimethyladamantyl, 4-cumyl phenyl methacrylate, cyanoethyl acrylate, cyanoethyl, 4-biphenyl, 4-Biphenylmethacrylat, 2-naphthyl, 2-naphthyl methacrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl methacrylate, , dimethylaminoethyl acrylate, dimethylaminoethyl, 2-butoxyethyl, 2-butoxyethyl, 3-methoxyacrylate, 3-methoxybutyl, Phenoxyethylacrlylat, phenoxy ethyl methacrylate, 2-phenoxyethyl, Butyldiglykolmethacrylat, ethylene glycol acrylate, Ethylenglycolmonomethylacrylat, methoxy polyethylene glycol methacrylate 350, methoxy polyethylene glycol methacrylate 500, Propylenglycolmonomethacrylat , Butoxydiethylenglykolmethacrylat, ethoxytriethylene, Octafluoropentyl acrylate, octafluoropentyl methacrylate, 2,2,2-trifluoroethyl, 1,1,1,3,3,3-hexa-fluoroisopropylacrylat, 1,1,1,3,3,3-Hexafluoroisopropylmethacrylat, 2 , 2,3,3,3-pentafluoro-propyl methacrylate, 2,2,3,4,4,4-Hexafluorobutylmethacrylat, 2,2,3,3,4,4,4-heptafluorobutyl, 2,2,3,3 , 4,4,4-Heptafluorobutylmethacrylat, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluorooctylmethacrylat or macromonomers such as 2-Polystyrolethylmethacrylat (molecular weight Mw of 4000-13000 g / mol), poly (methyl methacrylate) ethyl methacrylate (Mw 2000 to 8000 g / mol).</li></ul>

p0044Examples are the following monomers for component (d) may be mentioned: dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, N- (1-methylundecyl) -acrylamide, N- (n-butoxymethyl) acrylamide, N- (butoxymethyl) methacrylamide, N- (ethoxymethyl) acrylamide, N- (n-octadecyl) acrylamide, also N, N-dialkyl substituted amides such as N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-Benzylacrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, N-tert-octylacrylamide , N-methylolacrylamide, N-methylolmethacrylamide, acrylonitrile, methacrylonitrile, vinyl ethers such as vinyl methyl ether, ethyl vinyl ether, vinyl isobutyl ether, vinyl esters such as vinyl acetate, vinyl chloride, vinyl halides, vinylidene chloride, vinylidene halides, vinyl pyridine, 4-vinylpyridine, N-vinylphthalimide, N-vinyllactam, N vinylpyrrolidone, styrene, a- and p-methyl styrene, a-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, 3,4-dimethoxystyrene.

p0045Monomers of component (c) can advantageously also be selected such that they contain functional groups which support subsequent radiation crosslinking (for example, by electron beams, UV). Suitable copolymerizable photoinitiators include benzoin acrylate and acrylate benzophenone. Monomers that support a crosslinking by electron beams, are, for example, tetrahydrofurfuryl acrylate, N-tert-butylacrylamide, and allyl acrylate.

p0046Particularly advantageously comprises a matrix forming polymer polymerized also acrylic and / or methacrylic acid.

p0047For a preferred application of the polymer foam as a PSA, the proportions of the respective components (a), (b), (c) and (d) is preferably selected such that the polymerization product has a glass transition temperature ≤ 15 ° C (DMA at low frequencies). For this purpose, it is advantageous for the monomers of component (a) with a proportion of 45 to 99 wt .-%, the monomers of component (b) with a proportion of 1 to 15 wt .-% and the monomers of the components (c) and (d) to select a proportion of 0 to 40 wt .-%, wherein the information on the monomer mixture for the "base polymer", ie without additions of any additives to the completed polymer, such as resins, etc. are based.

p0048For an application of the polymer foam as hot melt adhesives, that is, as a material which becomes tacky only heating, the fractions of the respective components that the copolymer (a), (b), (c) and optionally (d) is preferably selected such a glass transition temperature (T_G) Between 15 ° C and 100 ° C, more preferably between 30 ° C and 80 ° C and more preferably between 40 ° C and 60 ° C.

p0049The matrix may also comprise fillers such as titanium dioxide, zinc oxide, carbon black, chalk (= calcium carbonate, CaCO₃) And other additives such as aging inhibitors, flame retardants, fungicides and the like. It is also possible in addition to the expaniderbaren microballoons - ie those with a polymer shell and a propellant therein, obtained by evaporation, preferably enables a large increase in volume - to also use non-expandable microballoons, for example hollow glass microspheres.

p0050It is common to the aforementioned ingredients to the temperatures, pressures and shear stresses occurring in the process as sensitive are considered the microballoons to mix first and which are considered sensitive microballoons -. Possibly possibly together with thermally also sensitive crosslinkers and admix Vernetzungsverzögerern later , This type of protection of the microballoons but not easy on the manufacturer's budget, because thereby the total mixing time and the total length of the required mixing unit is quite long, and it spares especially not the matrix polymers which are exposed to a relatively long mechanical and thermal load.

p0051After the description of the principles and main developments of the method according to the invention now to ensure appropriate device:<ul><li>The ring gear of the planetary roller extruder is also known as "toothed barrel" or "housing" or "hollow roll" or "roll shell", "internally toothed cylinder", and the like; there is a considerable variety of terms. No matter how it is called, be resting easier both its heating and cooling be. For heating of the ring gear - in particular for processing of acrylates any kind preferred as the base polymer, as already elaborated earlier - and in any case there is enough hot water or steam is available from other processes, hot water or steam should be used, otherwise Elektroheizdrähte. For cooling of the ring gear - in particular for the processing of mainly polyolefinsichen masses preferably, as already elaborated earlier - should in the liquid passages of the housing circle cold water through a series connected cooling unit - preferably working according to the Linde principle - and a circulating pump flows.</li></ul>

p0052To produce the temperature gradient according to the invention in radial section of the extruder and the sun (= sun roller = central spindle) is performed actively tempered expediently; in particular for the processing of acrylates of any kind as a base polymer, should - be withdrawn from the heat Sonnenrade - as already explained in greater detail earlier. For this purpose, a cooling device should be disposed therein, preferably cold water channels. This cold water channels should with an external cooling source - be connected - preferably working according to the Linde principle.

p0053In the control device of the cooling of the ring gear (as described above) or the sun gear (as described last) through the measured temperature fluctuations expediently a crossover and it will be the lower-temperature fluctuations regulated by acting on the driving power of the refrigerator and the higher frequency variations in temperature by acting on the drive power the circulation pump between the refrigerating unit and ring gear or sun roller, because the circulation pump power with a smaller inertia is adjustable as the compressor capacity in the refrigeration producers.

p0054Go back to the process:<ul><li>On the way to the invention realized by the inventors that an improvement of the reached to a point of the process homogeneity degree more serious falls, the higher the hitherto already reached degree of homogeneity. By "poor" to get "enough" falls therefore lighter than the step from "adequate" to "satisfactory" and this in turn easier than the other to "good". The inventors had further recognized that when mixing almost alone on an equal distribution of materials - for example, micro-balloons - but not on an equal distribution of different temperatures individuals - be they molecules, as in the case of the polymers and resins, there are pieces like arrives the same substance - in the case of microballoons. Based on this, he developed the idea to suspend the substances to be mixed significantly different temperatures. The resulting increased urge to natural temperature compensation also promotes material mixing. This advantage is particularly good at mixing microballoons to advantage, because they are relative to the size of polymer molecules huge.</li></ul>

p0055Meanwhile the Temperierungsunterschied invention is useful even in the cross-sectional planes early reached by mixing stream, it is even more important in the past for mixing provided surplus (= module). Why is there preferably the set temperature difference between hot and cool components is greatest. After the overarching goal of the invention, the more careful processing and the matrix polymers - from mechanical as thermal loads - is, it seems recommendable, in the extruder zone where the final mixing is carried out, especially far cool the cold component and less, the hot component particularly well to heat.

p0056In the Processing to foaming acrylates all types preferred orientation of the inhomogeneous temperature field - ie with respect to the Hohlrade significantly cooler central spindle - the inventor has further concluded that the mixture performance enhancing cooling of the sun roller (= sun) - with simultaneous heating of the ring gear - in longitudinal section of the mixing unit considered in the final stages of mixing should be particularly large. Therefore, it is preferable that the refrigerant flows against the conveying direction of polymer inside the sun roller.

p0057Another development of the method is characterized in that the expandable microballoons are first suspended before its discharge into water. Advantageously, in combination with the fact that only this suspension - not the dry microballoons - are introduced into the matrix-forming polymer composition and then mixed, started later expansion of the microballoons at temperatures lower than the expansion starting temperature specified by the micro-balloon manufacturers. This manufacturer's instructions - so the new finding - applies namely only to the dry microballoons.

p0058The measure of the previous suspension in water so not only reduces the dust formation and explosion hazard at the filling site of the microballoons but also acts as a plasticizer on the envelope of the microballoons, especially when these polyacrylonitrile rubber. Although the suspension of expandable microballoons in water is known - Akzo Nobel can buy such pastes under the brand name Expancel © finished - but not the retroactive effect of this suspension to the expansion behavior of the microballoons and not this knowledge-use doctrine, the expansion below the expansion starting start temperature. The lower temperature level during expansion in the further developed process preserves the matrix polymers further.

p0059The inventor has recognized that the suspension in water of the mixture in such a manner supplying water that - apart from the water which diffuses into and through the envelope of the microballoons - arise almost no independent water droplets in the mixture but the microballoon surfaces are wetted with water , At least, this is achieved with the microballoons of a coating consisting substantially of polyacrylonitrile. The inventor expected that this effect can also be achieved with other types of microballoon as long as the polarity of the sheath material matches that of water. This causes wetting of the microballoon surfaces - so, the inventor found - lubrication and adhesion reduction between microballoon and matrix material, which facilitates the mixing continued while the shear stress of the microballoons lowers when mixing.

p0060Both the self-made water-microballoon emulsions as well as the finished purchased but included the problem that occurs at rest for separation, because the specific gravity of water and microballoons do not match. Such separations, the inventor recognized laboriously, were the reason for such low-frequency interference in the microballoon dosage over the extrudate that this could be offset by no more mixing and were reflected in the standing at the end product as a sealing variation. The obvious solution proposal, to stir the emulsion stock constantly performed, either with insufficient stirring power to remedy this error, or with excessive rate of straight through this stirring destroyed microballoons. At least for the masses to be already prepared with black paint, the inventors devised the simple but effective teaching, to go from the two-fluid to a three-component system, namely to take as a third substance to carbon black. Be particularly effective, it has been found only soot to emulsify in water to a sufficiently low viscosity black paste and only then add the microballoons, after which a thicker black paste is present.

p0061Thus preferably the self-adhesive composition - - In order to achieve maximum strength in the finished extruded product, the water content of the mixture should be lowered again at some point after the introduction of the aqueous soot-microballoon suspension; preferably - namely for the purpose of obtaining long and optimum utilization of the lubricating effect by the water - carried out the only after extensive achieve a homogeneous distribution of the microballoons in the matrix-forming composition. A water removal forcierende vacuum application takes place therefore preferably only in the late stage of mass processing. You may order the removal of water in the last shot of the planetary roller extruder, but you can arrange it behind in a separate unit, for example, a single screw extruder.

p0062During wherever arranged water withdrawal a negative pressure should be applied to its promotion. Further promotion of the removal of water temperature remains close expedient of 100 ° C or just above; of this preferred feature can be particularly make carefree use, if the microballoon Type is selected such that the expansion starting temperature is above 100 ° C.

p0063The previously disclosed herein and in the six paragraphs idea to soften the microballoons by emulsifying in water and so reduce their expansion starting temperature and continued at least significant parts of the expansion then at a temperature below the - so far angegebenen- by manufacturers for dry microballoons expansion starting temperature execute, can be realized autonomously also, ie independent of an inhomogeneity of the temperature field in the cross section along the main invention of this application. The same also applies to the preferred developments of this by-thought, namely first emulsify soot in water and then yet to emulsify microballoons to and, at least large portions of the registered with the emulsion feed into the composition to be extruded water at the end of mixing or after mixing again be deducted.

p0064But if done the water discharge in connection with the inhomogeneous temperature field according to the main invention, then it should at least one of the two boundary surfaces of the mixing chamber having a temperature of close to or above 100 ° C; should therefore in the dewatering section in connection with the embodiment in a planetary roll extruder and in connection with acrylates and / or methacrylates as the base polymer of the processed mass, at least the ring gear have a temperature of almost 100 ° C or over. The particular advantage of a drainage with a Hohlradtemperatur just below 100 ° C - preferably about 95 ° C - is that in the mass to be dehydrated until the boiling point is exceeded by the additional registered Walk heat. But this Walken also ensures that no large steam caverns are created, which could degrade the quality of the finished product. If this Walken now out - either by a malfunction or by a break of the system of supervision staff - below the evaporation ahead uncontrollably. The development of hazardous vapor pressures is automatically suppressed.

p0065Just when the hotter boundary surface remains below 100 ° C, it is useful if the other surface - ie the central spindle in the case of drainage of acrylates and / or methacrylates in the last shot of a planetary roller extruder - or at least not too cool , In the dewatering step no longer the highly inhomogeneous temperature distribution in the cross-sectional plane is currently preferred that into the mixing was still shots so advantageous previously. To continue forming solution even to this problem, it is preferable that "cooling" channels in this drainage area of ​​the central spindle as large drill that its inside can be lined with a heat insulating sleeve. With this measure, two advantages are attained, namely firstly that the central spindle cools hardly where preferably flowing from back to front coolant is not yet cold, and secondly, that the central spindle in the region lying in front of this drainage and degassing the mixed area, in which the inner wall the cooling channels is left blank, particularly well cooled, because the coolant has hardly heated when passing through the drainage and Entgasungsbereiches. The heat insulating sleeve is expediently of a syntactically foamed polymer tube. A high void content therein ensures heat insulation.

p0066The same applies when using other types of extruders and analog inverse applies in a temperature field reversed orientation, as is preferred for processing polyolefinic compositions; However, in the polyolefinic for mixing materials with expandable microballoons in preferred orientation of the temperature inhomogeneity in the mixed shots - namely hot sun spindle and cool gear - the broad object of this inhomogeneity in dewatering and degassing shot because of the separate controllability of the cooling channels of different shots particularly easy and exactly accessible by allowing circuits in the respective channels there just hot and not cold water.

p0067Thus during this removal of water, the microballoons or at least not expand too much on, come for this development of the invention particularly the microballoon types in question, the expansion starting temperature is even in the suspended state even above 100 ° C; according to the experience of the inventor with such microballoons whose envelope consists essentially of polyacrylonitrile, higher by 25 ° C expansion starting temperature should be expected in the dry goods.

p0068Preferably, according to the method and its preferred developments described above self-adhesive tapes are produced. For this purpose, the compound containing the microballoons polymer composition<ul><li>applied in a single layer on a support of a too one-sided self-adhesive tape or forming</li><li>is applied in each case a single layer on both sides of a support to a forming double-sided self-adhesive tape or</li><li>applied in a single layer on a liner, which this assembly is laminated together with either a composite after the first indent or already forms a double-sided, strapless self-adhesive tape.</li></ul>

p0069To appropriate for the method implementing device:<ul><li>Expediently, such a planet roll extruder is provided for performing a method according to the invention in a planetary roller extruder with a temperature gradient from the hot to the cooler Hohlrade Sonnenrade, wherein said ring gear includes a heater. Opposite a planetary roller extruder with heat alone by the introduced flexing a much shorter and more reproducible starting behavior of the system is achieved, if this can not be operated around the clock. Also the height of the temperature gradient according to the invention can be adjusted within wide limits and with higher precision.</li></ul>

p0070Absolutely essential for achieving the preferred orientation of the temperature gradient - namely the hot Hohlrade toward the cooler Sonnenrade - is that the sun contains a cooling device. Without a cooling device in Sonnenrade most a temperature gradient inverse orientation can be produced.

p0071For a method implementing the preferred suspension of microballoons in water prior to their introduction and a subsequent dehydration expediently a manufacturing facility is provided behind the - on or mehrschüssigen - planetary roller extruder and prior to the first or single shaping unit (extrusion and / or calender) having a negative pressure zone. In the vacuum zone of dehydration is very successful, particularly as water vapor.

p0072Among the products:

p0073The invention also includes a self-adhesive tape, which contains a foamed self-adhesive composition or is composed exclusively of this self-adhesive composition, which was prepared according to the inventive method. These self-adhesive tapes are characterized in that the molar mass distribution corresponds particularly well in its self-adhesive compound with the molecular weight of the polymers used in the procedure beginning. The amount of waste in the largest molecular masses and the increase in small molar masses thus detected is particularly low. It is expected that the gentler polymer treatment results during the production of self-adhesive tape according to the invention to its higher continuous power, so later eintretendem fatigue failure.

p0074Inventive adhesive tapes are further distinguished by a particularly smooth surface; depending driven care and purity of the ambient air - and thus also of the extrusion - achieve self-adhesive tapes already produced solely by extrusion average roughness 12-2 microns. These self-adhesive tapes act by way of active than one would expect only from the rheological data of the mass ago. This can be used to the extent that a higher degree of crosslinking is set - the tack-reducing side effect may indeed be tolerated to a greater extent - in order to achieve even higher shear stability times.

p0075Because of the particularly high fatigue resistance inventively processed self-adhesive compositions, it is sufficient for the production of most self-adhesive tapes, if the self-adhesive layer or layers are made from a single layer of an inventively processed self-adhesive composition.

p0076The invention is explained in detail using a preferred embodiment:<ul><li>First, the base polymer was prepared in free-radical polymerization in a conventional reactor; time, he was charged with</li><li>54.4 kg of 2-ethylhexyl acrylate,</li><li>20.0 kg of methyl acrylate,</li><li>5.6 kg of acrylic acid and</li><li>53.3 kg solvent mixture of acetone / isopropanol (94: 6).</li></ul>

p0077After stirring for 45 minutes - under nitrogen gas highly enriched atmosphere for suppressing a fire or explosion - the reactor was heated to 58 ° C and 40 g of Vazo^®67 of the manufacturer DuPont - that is 2,2'-azobis (2-methylbutyronitrile) - added. The external heating bath was heated to 75 ° C and the reaction was conducted constantly at this external temperature. After one hour a further 40 g of Vazo 67 was added and after a further four hours, the solution with a further 10 kg of solvent - again acetone / isopropanol mixture (94: 6) to facilitate the -verdünnt Restmonomermigration and thereby to increase the degree of polymerization and thus to lowering the residual monomer content. After five and after seven more hours each 120 g of Perkadox 16 © were the manufacturer Akzo Nobel - this is bis (4-tert-butylcyclohexyl) peroxydicarbonate - refilled to Inganghalten the polymerization reaction. After five more hours - after a total of 22 h reaction time - the polymerization was terminated. In the reactor, until then a solids content of 55.9% was achieved.

p0078The polyacrylate thus obtained was measured in the laboratory for internal quality control. For this purpose has been reduced by a small amount of sample in a vacuum oven the residual solvent content to below 1 ‰, after which the polymer was dissolved in 99 wt .-% toluene (= methyl benzene according to IUPAC nomenclature). The K value was then according to the Fikentscher method of measurement - ie with a temperature-controlled at 25 ° C BIRD OSSAG viscometer - measured. The measured K value was 58.8, and serves as a measure of the average molecular size of high polymer compounds (see also<nplcit id="ncit0002" npl-type="b"><text>Journal Polymer, born 1967, issue 8, pages 381 ff</text></nplcit>.). Was further measured an average molecular weight of M_w = 746,000 g / mol, a polydispersity D (M_w/ M_n) Of 8.9 and a static glass transition temperature Tg of -35.6 ° C.

p0079This serves as the base acrylate was then concentrated in a single-screw extruder to a residual solvent content below 0.3 weight percent.

p0080In addition to the above-described preparation of the base polymer, the microballoons were prepared; to have microballoons of type Expancel 051 DU 40 manufacturer Akzo Nobel - unexpaniderter diameter between 10 and 16 micrometre - placed in an aqueous carbon black paste of Type Levanyl Black N-LF manufacturer LANXESS Germany GmbH. The purchased carbon black paste contains Levanyl by the knowledge here 40% carbon black and 60% water. The carbon black stabilized in the water right from the start the ternary emulsion produced. By the addition of the microballoons to carbon black paste By "stabilize" is meant here a physical stabilizing, thus preventing a separation between the three components by their different density. Because of the already high water content in the purchased carbon black paste needs to be supplied to this no additional water before mixing the microballoons. Namely, 69.5 parts by weight of microballoons of type Expancel 051 DU were 40 added to 100 parts by weight of carbon black paste Levanyl. Thus, the paste thus produced contained 23.6% carbon, 35.4% water and 41% microballoons.

p0081To benefit from the preferred lowering the temperature required for the expansion starting, the invention is stored Further developing this paste containing the microballoons only at room temperature. Although the desired effect can be detected after a few minutes storage time, but in order to bring this desired effect for maximum flowering and especially the consistency over the storage period and thus to quantitatively particularly lightweight and reliable reproducibility, a storage period of at least 12 hours is recommended. After this time, the effect of the expansion starting temperature reduction has so far asymptotically approached its maximum for t → ∞, that further storage time this effect hardly increased.

p0082Only after the plasticizing effect of water was set to the substantially nitrile containing shells of the microballoons, this paste was mixed from soot, water and micro-balloons to the base polymer and indeed in 2.44 parts by weight to 100 parts by weight polymer. This paste was added to the feed tube of the planetary roller extruder.

p0083Furthermore funnel were in the planetary roller extruder weight proportionally based on 100 phr base polymer at this: <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="51mm" /><colspec colnum="2" colname="col2" colwidth="43mm" /><thead><row><entry valign="top">additives</entry><entry valign="top">Proportion of ingredients [w phr%]</entry></row></thead><tbody><row><entry>acrylate</entry><entry align="center">100</entry></row><row><entry>Dertophene T110</entry><entry align="center">40</entry></row><row><entry>aqueous soot-microballoon paste</entry><entry align="center">2.44</entry></row><row><entry>Epikure © 925</entry><entry align="center">0.2</entry></row><row><entry>Polypox® R16</entry><entry align="center">0.19</entry></row><row><entry>sum</entry><entry align="center">142.83</entry></row></tbody></tgroup></table></tables>

p0084Polypox® R16 is available from Dow Chemical, used as crosslinkers and by IUPAC Penthärythritol polyglycidyl.

p0085Epikure 925 offered by Hexion Specialty, also serves as a crosslinking agent and is according to IUPAC triethylenetetramine.

p0086Divided based on a total of 100 w% and the paste shown in its components results in that:<tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="51mm" /><colspec colnum="2" colname="col2" colwidth="38mm" /><colspec colnum="3" colname="col3" colwidth="14mm" /><thead><row><entry valign="top">additives</entry><entry valign="top">Proportion of ingredients [w%]</entry><entry valign="top" /></row></thead><tbody><row><entry>acrylate</entry><entry align="center">70.013</entry><entry align="center" /></row><row><entry>Dertophene T110</entry><entry align="center">28.005</entry><entry align="center" /></row><row><entry>aqueous soot-microballoon paste</entry><entry align="center">1,709</entry><entry align="center" /></row><row><entry>of water</entry><entry align="center" /><entry align="center">0.605</entry></row><row><entry> Expancel 051 DU 40</entry><entry align="center" /><entry align="center">0.701</entry></row><row><entry> soot</entry><entry align="center" /><entry align="center">0.403</entry></row><row><entry>Epikure 925</entry><entry align="center">0,140</entry><entry align="center" /></row><row><entry>Polypox® R16</entry><entry align="center">0,133</entry><entry align="center" /></row></tbody></tgroup></table></tables>

p0087For the implementation of this embodiment of the inventive method a vierschüssiger planetary roller extruder 1 from Entex used. Even before the first shot is a catchment area in which a hopper is feeding directly on the central spindle 5, in the so no planetary roller 6 revolve around the central spindle. 5

p0088In this funnel both the acrylate polymer described above as well as the resin Dertophene T110 is dosed via gravimetric fed. To further increase efficiency of mixing it has proved advantageous to preheat the resin to 150 ° C. Advantageously, the resin is fed as a strand from an upstream screw extruder.

p0089The acrylate polymer may be added as granules. Not technical but from economic reason - the polymer has been prepared in operation of the inventor itself - but is also, this polymer has been fed in strand form in this example of another extruder; as the granulation step could be saved. In rational process control of these other extruder is identical to the concentrating extruder at the end of the polymer manufacturing process and it is a continuous production. Particularly advantageous has been found, additional feed the strand of Acrylatcolpolymer with 140 ° C.

p0090From this feed area - in which the central spindle is 5 traversed by a cooling duct 5.1, in the coolant heats of about 41 ° C to 44 ° C, and are traversed in the housing and filling shaft of channels, in the chilled at 50 ° C water is introduced - then reaches the ground in the first shot of the planetary roller extruder 1 through the axial feed of the helical teeth of the continuous central spindle 5. Not only to dissipate here supplied by drumming heat, but also to lower the melt temperature is in this first shot both the ring gear and the central spindle cooled.

p0091Each of the four shots of the equipment used was about 1.1 meters long. The pitch circle diameter of the internal teeth of the ring gears was about 550 mm and the pitch circle diameter of the planetary rollers about 50 mm. The central spindle rotating at 30 rev / min.

p0092The figure shows schematically the top left of the planetary roller extruder 1 in cross section through the first shot (= module 1) and the set there the temperatures Temperierungsfluides water.

p0093Contrary to the polymer delivery direction down to 50 ° C chilled water in the cooling ducts 7.1 of the housing pumped 7 (= internally toothed hollow = hollow roll = roll cylinder) and withdrawn at the beginning of the first shot of about 55 ° C again and passed into a first cooling unit, where it is cooled down again to 50 ° C again at the end of this first shot initiate it back into the housing. 7 The figure shows each initiation temperatures of the heating media.

p0094The central spindle 5 is cooled by a cooling channels 5.1. Unlike the tempering 7.1 of the housing 7, which are separated from module to module, runs through the cooling channel 5.1 the central spindle 5 continuously just like the central spindle 5 itself continuously. Immediately control can therefore be only the coolant temperature at the point of discharge at the end of last - here: fourth - shot. At this point, the rear spindle cooling water was introduced at 30 ° C. It reaches the end of the first shot - so now have measurements and a model calculation result - 37 ° C and leaves it at 41 ° C to flow from there into the catchment area already described, there further to about 44 ° let C heat and from there eventually to flow to a second cooling unit, where it is cooled back to 30 ° C down, before it is passed again at the end of the fourth shot through a sliding seal back into the cooling channel 5.1.

p0095The transfer points from one to the next shot are not penetrated by planetary roller. Therefore at these transfer points More particularly prone dosed added. At the transfer point from the first to the second shot, the three-component paste of water, carbon black and microballoons is metered gravimetrically.

p0096The figure shows schematically the upper right the planetary roller extruder 1 in cross section through the second shot (= module 2) and the set there the temperatures Temperierungsfluides water. In the housing channels 7.1 this excess 115 ° C is introduced hot water (ie standing under excess pressure). Here, this water has a-heating and no cooling effect as the Gehäusetemperierwasser in the catchment area and in the first shot. The cooling water of the central spindle happens to about 34 ° C, the boundary between the third and second shot and leaves the second shot towards the first shot for about 37 ° C.

p0097Due to the good thermal conductivity of the metals used for the housing and the spindle for the respective surface temperature is dense at the temperature of each temperature-controlled water. On the inside of the housing 7 show heat transfer calculations an average surface temperature in this second shot of about 112 ° C. Show on the outside of the central spindle 5 heat transfer calculations on an average surface temperature in this shot of 38 ° C. The temperature difference between two surfaces is thus about 74 ° C. It leads to an invention considerably inhomogeneous temperature field in the cross-sectional plane through this second shot of the planetary roller extruder.

p0098The planetary roller 6 take - for clarity not shown in the figure - a lying between these extremes of temperature. According to a model calculation for heat transfer, the planetary gears on their ring gear 7 side facing a temperature of about 80 ° C, and on its side facing the sun-facing side of about 79 ° C.

p0099This temperature conditions results in a thin layer as expansion of mass in distant analogy to the carbon distribution in a Damascus steel blade. The microballoon expansion is anticipated in the ring gear 7 and between 6 and planetary gear 7 - there, however, only in the layer Executed located sufficiently close to the Hohlradoberfläche. That surprisingly, still at the end, the entire mass is beautifully expanded homogeneously, the inventor explained by the extremely good mixing performance just because of the large temperature difference, which already leads expanded subsets with not expanded subsets also to a mixing. The formerly continuous expansion process is here so temporally and spatially divided into a plurality of expansion portions.

p0100At the transfer point between the second and third shot nothing more was added. The corresponding cover remained closed.

p0101The figure shows schematically the bottom left of the planetary roller extruder 1 in cross section through the third shot (= module 3) and set there the temperatures Temperierungsfluides water. In the housing channels 7.1 this excess 115 ° C is also introduced hot water. Here, this water has a lower-heating effect as the second shot. The cooling water of the central spindle happens to about 32 ° C, the boundary between the fourth and third shot and leaves the third shot towards second shot at about 34 ° C.

p0102Due to the good thermal conductivity of the metals used for the housing and the spindle for the respective surface temperature is dense at the temperature of each temperature-controlled water. On the inside of the housing 7 show heat transfer calculations an average surface temperature in this second shot of about 113 ° C. Show on the outside of the central spindle 5 heat transfer calculations on an average surface temperature in this shot of 35 ° C. The temperature difference between two surfaces is thus about 78 ° C. It leads to a somewhat less homogeneous temperature field in the cross-sectional plane through this third than in the second shot of the planetary roller extruder.

p0103Also in this third shot, take the planet rollers at a lying between the aforementioned extremes temperature. According to a model calculation for heat transfer, the planet gears on its side facing the ring gear a temperature of about 79 ° C, and on its side facing the sun of about 78 ° C.

p0104This compared with the second shot only slightly further pointed temperature conditions also creates a thin film as expansion of mass. The microballoon expansion is anticipated in the ring gear 7 and between 6 and planetary gear 7 - there, however, only in the layer Executed located sufficiently close to the Hohlradoberfläche.

p0105At the transfer point between the third and fourth shot (= module 4) the easy einmischbaren but temperature-sensitive crosslinking agent Polypox® R16 and Epikure 925 were metered gravimetrically.

p0106The figure shows schematically the bottom right of the planetary roller extruder 1 in cross section through the fourth shot (= module 4) and set there the temperatures Temperierungsfluides water. In the case of this shot channels 7.1 50 ° C is introduced hot water and a cooling effect. The cooling water of the central spindle occurs at the end of which an approximately 30 ° C and happens to about 32 ° C, the boundary between the fourth and third shot.

p0107The significant reduction of the process temperature in this shot allows a vacuum application for expelling air and water vapor without significant further progress of the expansion of the microballoons. Also a good distribution of the two cross-linking agent is reached in this step.

p0108Then the mass was transferred into a conventional temperature-screw extruder which operated the reheating of the mass to the extrusion temperature with simultaneous pressure buildup. Although needed for a sufficiently lightweight Durchfließbarkeit the extrusion die there a temperature to be adjusted, which was just above the expansion starting temperature of the microballoons, but the interaction of high pressure in this single screw and - by previously reached Expansion reduced gas pressure in the microballoons resulted in only very small increase in expansion. The extruded profile showed an unusually smooth surface with an average surface roughness less than 12 microns.

p0109A carried out in a comparative test, not consuming the highly inhomogeneous temperature field in the second and third shot of the planetary roller extruder led to poorer uniformity and greater average roughness, which is why these high inhomogeneity is considered a causal factor in the success achieved. Documents in one shot both the spindle temperature and the Hohlradtemperatur above - possibly lowered by the action of water - expansion starting temperature of the microballoons so succeeded not a good homogeneity of the foam. Documents, however both temperatures below the expansion starting temperature, succeeded no foaming.

p0110It follows as a part of the description, a list of reference numerals:<dl id="dl0001" compact="compact"><dt>1</dt><dd>Mixing unit, planetary roller extruder</dd><dt>2</dt><dd>Mixing space in the mixing unit 1</dd><dt>3</dt><dd>first surface having a temperature T₃ has limited and the mixing chamber 2</dd><dt>4</dt><dd>the second surface having a temperature T₄ has limited and the mixing chamber 2</dd><dt>5</dt><dd>Central spindle of the planetary roller extruder = sun gear sun roller =</dd><dt>5.1</dt><dd>Cooling duct in 5</dd><dt>6</dt><dd>Planet rolls a planetary roller extruder</dd><dt>7</dt><dd>internally toothed ring gear of a planetary roller extruder = hollow roll</dd><dt>7.1</dt><dd>Cooling channels in 7</dd></dl><dl id="dl0002" compact="compact"><dt>T_e</dt><dd>expansion temperature</dd></dl>