Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
  • C09D183/14—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers in which at least two but not all the silicon atoms are connected by linkages other than oxygen atoms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
  • B29C33/60—Releasing, lubricating or separating agents
  • B29C33/62—Releasing, lubricating or separating agents based on polymers or oligomers
  • B29C33/64—Silicone
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31652—Of asbestos
  • Y10T428/31663—As siloxane, silicone or silane

Definitions

• the present invention relates to the use of certain compositions from certain sol-gel materials as non-stick coatings and devices for the production and refinement of polymers, in particular rubbers, characterized in that they are made from a hydrophobic sol-gel coating by means of such a non-stick coating. Material.
• the protective coating is obtained by applying an alkaline solution of an alkylene sulfonic acid-substituted (hydroxy) ⁇ aphtol.
• the protective coating obtained is yellow to brown and shows good effectiveness against polyvinyl chloride (hardly any deposits after
• the object of the present invention was therefore to provide apparatus for the production and processing of polymers on which the deposition of polymers is significantly reduced or prevented by applying a suitable coating and the coating does not have to be renewed after each production or processing step.
• the object of the present invention was to provide appropriately equipped apparatus for the production and processing of
• the present invention therefore relates to the use of certain compositions of certain sol-gel materials as non-stick coatings and apparatus for the production and processing of polymers, in particular rubbers, characterized in that they have a non-stick coating made of a hydrophobic sol-gel material ,
• Hydrophobic sol-gel materials in the sense of the invention are essentially three-dimensionally crosslinked, organically modified amorphous glasses which are obtained by hydrolysis and condensation reactions of low molecular weight compounds, e.g. Silicon alkoxides can be obtained. After hydrolysis and condensation, the hydrophobic sol-gel materials according to the invention preferably have at least one structural element of the formula (I)
• i 0 or 1
• j 1, 2 or 3
• k 0, 1 or 2
• E is oxygen or sulfur
• R 1 is an optionally substituted alkyl or aryl radical or a bridging one
• Alkylene or arylene radical and R is an optionally substituted alkyl or aryl radical
• the sol-gel materials particularly preferably have a structural element of the formula
• j is 1, 2 or 3
• k is 0, 1 or 2
• R 1 is a bridging C 1 -C 6 -alkylene radical
• R 2 is an optionally substituted alkyl or aryl radical
• the sol-gel materials very particularly preferably have a structural element of the formula (III)
• R 1 is a bridging d- to C -alkylene radical
• R 2 is a methyl or ethyl radical
• Polyfunctional organosilanes are preferably used for the production of sol-gel materials of the form n (I), (II) or (III), in which R 1 is an alkylene radical.
• these are monomers, oligomers and / or polymers, characterized in that at least 2 silicon atoms with hydrolyzable and / or condensation-crosslinking groups each have at least one Si, C bond, preferably at least one alkylene group (-CH 2 -) to one the unit linking silicon atoms are bound.
• Polyfunctional organosilanes with at least 3, better still with at least 4 silicon atoms with hydrolyzable and / or condensation-crosslinking groups are particularly preferred.
• alkoxy or aryloxy groups are particularly suitable, alkyloxy groups such as Methyloxy, ethyloxy, propyloxy or butyloxy called.
• Condensation crosslinking groups are in particular silanol groups (Si-OH).
• Molecular structural units can be, for example, linear or branched Q-C 2 o-alkylene chains, Cs-Cio-cycloalkylene radicals or C 6 -C 2 -aromatic radicals, such as phenyl, naphthyl or biphenyl radicals.
• the radicals mentioned can be substituted one or more times and can in particular also contain heteroatoms, such as Si, N, P, O or S, within the chains or rings.
• Coatings which are particularly resistant to chemicals are obtained if the linking structural unit of the polyfunctional organosilanes consists of linear, branched, cyclic or cage-shaped carbosilanes, carbosiloxanes or siloxanes.
• R, R and R independently of one another are C 1 -C 8 -alkyl radicals or phenyl radicals, preferably methyl, ethyl or phenyl radicals,
• a, b are independently 0, 1 or 2, preferably 0 or 1, and
• c, d and e, f independently of one another are greater than or equal to 1, preferably greater than or equal to 2, and
• X is a bridging structural unit for a linear, branched, cyclic or cage-shaped siloxane, carbosilane or carbosiloxane, preferably a cyclic or cage-shaped siloxane, carbosilane or carbosiloxane.
• Cyclic carbosiloxanes of the general formula (V) are particularly preferably used,
• R 7 , R 8 and R 9 independently of one another are C 1 -C 4 -alkyl radicals, h is 0, 1 or 2, preferably 0 or 1, and g is an integer from 1 to 4, preferably 2, and i represents an integer from 3 to 10, preferably 4, 5 or 6.
• cyclic carbosiloxanes are compounds of the formulas (Via) to (Vle), in which R 10 represents methyl or ethyl:
• oligomers of the cyclic carbosiloxanes mentioned in WO 98/52992 can of course also be used as polyfunctional organosilanes in the process according to the invention. It is also possible to use mixtures of various cyclic monomeric or else oligomeric carbosiloxanes.
• the sol-gel coating solution is prepared, for example, by mixing suitable low molecular weight compounds in a solvent, after which the hydrolysis and / or condensation reaction is initiated by adding water and, if appropriate, catalysts.
• the execution of such sol-gel processes is basically known to the person skilled in the art.
• EP-A 0 743 313 describes the syntheses of polyfunctional organosilanes and organosiloxanes and processes for preparing corresponding sol-gel coating solutions, from which the sol-gel materials of the formula (III) can in turn be obtained.
• the apparatus according to the invention for the production and processing of rubbers is produced a) by application of suitable sol-gel coating solutions according to customary methods, b) evaporation of volatile constituents such as solvents and condensation products c) and curing, if appropriate at elevated temperatures, which ultimately leads to the
• the application can be carried out according to all common methods, such as dipping, spraying, flooding, spinning, knife coating or pouring, whereby the substrate can be coated on the entire surface or only on parts thereof.
• Sol-gel coating solutions have the particular advantage that, due to their usually very low viscosity and good adhesion, e.g. on steel, an internally coating of complicatedly shaped apparatuses for the production and processing of rubbers can be carried out. For example, existing reactors and / or pipelines by passing the sol-gel coating solution through them,
• the application can be carried out directly after the surface to be coated has been cleaned appropriately.
• Typical materials from which the apparatus according to the invention can consist are metals or enamels, preferably iron-containing metallic materials, particularly preferably steels.
• the apparatuses according to the invention which are equipped with a hydrophobic sol-gel material, are particularly suitable for the production and enticing of chewing agents.
• chewing agents such as butyl and bromine and chlorobutyl rubber, polybutadienes, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, chloroprene rubber, ethylene-vinyl acetate rubber, butadiene rubber, styrene-butadiene rubber, ethylene-propylene.
• the rubbers can be produced by all established ner processes, such as the processes described in more detail below.
• a solvent e.g. organic compounds (or their isomer mixtures), such as hexane, cyclohexane, benzene, methylene chloride, toluene or technical mixes such as DH ⁇ 50 (50-70% by weight n-hexane + 5-10% by weight cyclohexane + 25- 35 %
• methylcyclopentane 0-5% by weight of 2-methylpentane, 0-10% by weight of 3-methylpentane
• the production and processing can be carried out at temperatures from -40 to 150 ° C, and
• Chloroprene is, as by F. Röthemeyer and F. Sommer, in "rubber technology"
• the technical polymerization of chloroprene is carried out in an aqueous emulsion using a radical mechanism at temperatures between 10 and 45 ° C.
• Resin acids, NaOH and the Na salt of a condensation product of formaldehyde and naphthalenesulfonic acid are used as emulsifiers.
• the polymerization is started by potassium persulfate or by redox systems. Due to the high reactivity of chloroprene, gel formation occurs even at conversions of 30% by weight.
• the gel content can be reduced by adding regulators (thiols, xanthogen disulfide or sulfur).
• the polymerization is terminated by inhibitors such as Thiuram disulfide and tert. Catechol.
• the excess monomer is removed by steam distillation in vacuo and recovered.
• the degassed latex is adjusted to a pH of approx. 6.0 with acid and coagulated on a freezer roller (-15 ° C).
• the rubber film is peeled off, washed and dried.
• the rubbers are classified according to the controllers used as follows:
• the monomers ⁇ sobutylene and isoprene are obtained as described by F. Röthemeyer and F. Sommer in “Kautschuktechnologie” Hanserverlag 2001, pp. 136-146, from the C4 and C5 cuts in naphtha production.
• Butyl rubber is produced by cationic copolymerization of isobutylene with small amounts of isoprene (0.5-2.5% by weight) in solution. The isoprene units are statistically distributed in the copolymer.
• the growth reaction of the cationic polymerization proceeds very quickly. Therefore, the molar mass depends to an unusually high extent on the polymerization temperature.
• the poppy seed mass increases inversely with temperature. If isobutylene is polymerized at room temperature, oligomers are obtained because the chain transfer reaction is dominant. Long-chain polymer chains are only obtained at low temperatures (approx. -90 ° C). Weakly polar, e.g. chlorinated
• Hydrocarbons methylene chloride, chloroform
• Lewis acids such as A1C1 3 or BF 3 are used as catalysts, which are activated by small amounts of cocatalysts (water, acids).
• 1-Butene acts as a regulator, but also deactivates the catalyst.
• the large-scale copolymerization of isobutylene and isoprene takes place in methylene chloride at temperatures of -100 ° C.
• the monomer concentration is 25% by weight, and A1C1 3 is used as the catalyst.
• the cooled monomer mixture (isobutylene and 0.5-3% by weight of isoprene) and the catalyst dissolved in methylene chloride are fed to a continuous reactor.
• the polymerization is still very rapid at -100 ° C.
• Polybutylene is insoluble in methylene chloride and is obtained as a suspension (precipitation polymerization).
• the polymerization suspension is continuously drawn off and hot water is added. Solvents and monomer residues are removed by stripping and returned to the process after separation by distillation.
• a stabilizer and a mixture of stearic acid and zinc stearate (0.4-1% by weight) are added to the polymer suspension. Stearates are used to avoid agglomeration of the particles.
• the remaining hydrocarbons are removed in vacuo. Dewatering takes place using an extruder. The dry crumbs are then pressed into bales.
• the monomers ethylene and propylene are obtained from natural gas or from crude gasoline by cracking, the termonomers are prepared by chemical synthesis as described by F. Röthemeyer and F. Sommer in “Kautschuktechnologie” Hanserverlag 2001, pp. 122-123.
• ethene and the diene component are metered in continuously.
• the Ziegler-Natta catalyst is added as a dilute solution. Efficient cooling is required to dissipate the considerable heat of polymerization of 2500 kJ per kg of polymer. Since the copolymer is soluble in hexane, the reaction is carried out after a conversion of approx.
• the suspension process enables significantly higher sales (up to 30% by weight) and the production of polymers with a higher poppy mass.
• the molar masses are regulated by adding hydrogen (hydride transfer).
• hydrogen hydrogen transfer
• ethylene, propylene and / or the termonomer are continuously fed to a fluidized bed reactor.
• the catalyst is placed directly in the fluid bed added.
• the gaseous monomers serve to fluidize the polymer particles as well as to remove the heat of polymerization.
• Butadiene can be polymerized anionically, coordinatively or radically as described by F. Röthemeyer and F. Sommer in “Kautschuktechnologie” Hanserverlag 2001, pp. 81-85 + 104-107.
• the anionic and coordinative polymerizations take place in solution, the radical polymerization takes place
• polybutadiene is produced with lithium alkylene or Ziegler-Natta catalysts, and the resulting polymers differ in their microstructure (ice, trans and vinyl content).
• the polymerization with Li-alkylene is carried out in solution and follows an anionic mechanism.
• Aliphatic or cycloaliphatic hydrocarbons are used as solvents.
• the monomer concentrations are between 10 wt .-% r 20, the reaction temperature is between 30-120 ° C. at
• the poppy mass depends only on the molar ratio of monomer to catalyst (no termination reaction). However, the polymerization can be carried out by adding
• Stoppers water, acids can be broken off.
• the microstructure depends on the type of alkali metal and the polarity of the solvent.
• the coordinative polymerization of butadiene with Ziegler-Natta catalysts takes place in solution.
• the mono m * merante oil is limited to 10-15% by weight.
• the polymerization takes place in a series of stirred autoclaves under an inert atmosphere. Hydrogen is used as the molecular weight regulator.
• the catalyst is deactivated and the monomer is protected by adding stabilizers.
• the Ziegler-Natta polybutadienes on the market are produced with the following catalyst systems: Titanium, cobalt, nickel, neodymium. The resulting polymers are characterized by a high cis content.
• the radical polymerization of butadiene is carried out in an aqueous emulsion.
• Redox systems hydroperoxide, sodium formaldehyde sulfonate and Fe (II) complexes
• catalysts hydroperoxide, sodium formaldehyde sulfonate and Fe (II) complexes
• fatty acids and resin acids are used as emulsifiers.
• the copolymerization of styrene and butadiene in solution takes place according to an anionic mechanism in solution. Due to the very different copolymerization parameters, the polymerization of butadiene takes place first and then styrene. This gives block copolymers with a defined transition region. By adding polar components (e.g. THF, tetramethylene diamine), the copolymerization parameters are changed so that the incorporation of styrene can take place statistically.
• polar components e.g. THF, tetramethylene diamine
• SBR can also be carried out radically initiated as an emulsion polymerization.
• the emulsion polymerization has the advantage that it is easy to control thermally. Large-scale production takes place in continuous stirred tank cascades. Styrene, butadiene, regulator and emulsifier system are dispersed in water and pumped continuously through the reactors cooled to 5 ° C.
• Water-soluble peroxides such as, for example, p-menthane hydroperoxide, are used as starters be activated in a redox system.
• the average residence time in the reactor is 8-10 hours.
• a radical scavenger for example dimethyldithiocarbamate.
• the latex formed after removal of the residual monomers has a solids content of about 65% by weight.
• Copolymers of butadiene and acrylonitrile are also known as nitrile rubber. They are of great importance for the manufacture of grease, oil and fuel resistant products.
• NBR Acrylonitrile butadiene rubber
• acrylonitrile is mainly produced by reacting propylene with oxygen and ammonia.
• Nitrile rubber is obtained by radical copolymerization of butadiene and acrylonitrile as by F. Röthemeyer and F. Sommer in "rubber technology"
• Emulsifiers are used fatty acids (lauric palmitic, oleic acid), resin soaps (disproportionated abietic acid) or alkyl aryl sulfonic acids. The latter reduce the pollution of the vulcanization molds.
• fatty acids lauric palmitic, oleic acid
• resin soaps disproportionated abietic acid
• alkyl aryl sulfonic acids alkyl aryl sulfonic acids.
• Alkali persulfates or organic peroxides with reducing agents (redox systems) applied.
• Acrylonitrile can be copolymerized with butadiene in any ratio.
• the acrylonitrile content of the commercially available rubbers varies between 15 and 50% by weight.
• the poppy seed mass is adjusted by means of a regulator (alkyl mercaptans).
• alkyl mercaptans alkyl mercaptans
• stoppers sodium hydrogen sulfide
• the carbosiloxanes cyclo- ⁇ OSi [(CH 2 ) 2 SiOH (CH 3 ) 2 ] ⁇ 4 and (oligomeric) cyclo- ⁇ OSi [(CH 2 ) 2 Si (OC 2 H 5 ) 2 CH 3 ] ⁇ 4 were as described in US 5,880,305 and US 6,136,939. All other components were commercially available and were used without further cleaning.
• Example 1 Production of sol-gel material 1 for coating equipment
• Example 3 Inner coating of a steel tube with the sol-gel material according to example lb)
• a sol-gel coating solution prepared according to Example lb 200 g were placed in a steel tube which was closed on one side and had a diameter of about 7 cm and a length of about 1.5 m. After the coating solution had been filled in, the still open side was also closed and the tube was rotated about its own axis for about 5 minutes. The closed ends were then opened, the coating solution was drained off and the steel tube was stored at ambient temperature for 15 hours. Finally, a stream of air at a temperature of approximately 80 ° C. was passed through for a further hour, as a result of which the sol-gel coating was further hardened. The visual inspection showed that the steel tube was evenly coated with an optically perfect coating (layer thickness approx. 5 ⁇ m).
• Example 4 Coating of steel sheet with the sol-gel material la) and testing the tendency to stick to a rubber solution
• Example 5 Coating of steel sheet with the sol-gel material la) and testing the resistance to dichloromethane
• the steel plates were then (technically) immersed in dichloromethane for 24 hours; finally the pencil hardness was checked again.
• the optically unchanged coatings no cracks, bubbles or detachment again showed the pencil hardness "2 H", i.e. the coating was not damaged even by storage in this aggressive solvent.
• Example 6 Coating of steel sheets with the sol-gel materials from Examples 1b) and 2) and testing the anti-stick effect during EPDM processing
• Sol-gel coating solution prepared was placed in a suitable immersion basin, then a steel sheet (approximately DIN A4 format) was immersed at constant speed and pulled out again. After briefly flashing off at room temperature (approx. 10 min), the coating was finally cured at 130 ° C. in a forced-air drying cabinet.
• the layer thickness of the optically perfect film was approximately between 6 and 8 ⁇ m, the adhesion was excellent (cross hatch test according to ISO 2409).
• Example 6b in accordance with the method described in Example 6b), another rough steel sheet was coated, the sol-gel coating solution from Example 2) being used for this. After curing, an optically perfect coating with a layer thickness of approx. 8-10 ⁇ m was obtained.
• test panels produced according to Examples 6a), 6b) and 6c) were tested for their anti-stick effect in a plant for drying EPDM (dryer line).
• the test was carried out under extreme production conditions, i.e. at a temperature of approx. 120 ° C and a pH value of the wet EPDM dispersion of less than 1.
• a commercial coating system made of Teflon and an uncoated, smooth VA steel plate were tested under the same conditions.
• the sheets were mounted in the running product stream for approx. 24 hours directly at the critical entrance of the feed chamber.
• the dryer entrance is known to be the most problematic for adhesion
• the coatings according to the invention made of sol-gel materials, very good adhesive marks (2) were achieved both on smooth and on rough surfaces. Surprisingly, despite the much simpler processing, the coatings according to the invention can achieve an anti-adhesive effect which is just as good as that of Teflon®.

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