MXPA00000555A - Pressure resistant and heat-stable insulating coatings for hollow bodies, and a method for producing the same - Google Patents

Abstract

The invention relates to a method for producing insulating coatings for hollow bodies. Said insulating coatings have polyurethane and/or polyisocyanurategroups, and are produced by reacting a) one polyisocyanate component with b) at least two compounds with hydrogen atoms which are active towards isocyanates and c) catalysts, optionally in the presence of d) other auxiliary agents and additives. The inventive insulating coatings are characterised in that organic or mineral hollow microspheres with an average particle size of between 5 and 200 mm and a density of between 0.1 and 0.8 g/cm3 are added to at least one of the components a) to d). The invention also relates to the use of the inventive insulating coatings for pipes used in offshore applications.

Description

Pressure resistant and thermostable insulation coatings for hollow bodies and a process for their manufacture Description of the invention: The invention relates to insulation coatings having polyurethane and / or polyisocyanate groups for hollow bodies, especially for tubes, as well as to a process for their manufacture. It is known to use, among others, PUR foams and PUR elastomers for the isolation of oil and gas pipelines in the field of marine drilling. EP-A 636 467 discloses how a thick-layer PUR coating of rotating bodies, such as rollers and tubes, can be implemented in an operating step. Among others, it is also known to cover tubes with PUR syntactic suspensions for their isolation. The profile of requirements for such insulation materials has clearly increased with the exploitation of new oilfields at greater sea depths. Among other things, the thermal stability of these materials, previously of 120 ° C, has been raised to 160 ° C and the resistance to the previous pressure of 50 bar (500 m depth of immersion) to 250 bar (2,500 m depth) of immersion). The polyurethane materials described above are, however, limited by a temperature stability REF .: 32482 constant of approx. 120 ° C. It has therefore been the object of the present invention to find insulation coatings for tubes having a skin stability greater than 120 ° C and a pressure resistance greater than 50 bar. It has surprisingly been found that with the combination of polyisocyanurate reaction masses with hollow microbodies stable to temperature and pressure, the desired requirements are achieved and that it can be used for straight and slightly curved tubes in the economic rotation coating process indicated in FIG. EP-A 636 467. Elbows and connections can be manufactured with the same base raw material in cast-in-mold. Accordingly, the invention relates to a process for the production of insulation coatings having polyurethane and / or polyisocyanurate groups for hollow bodies by reacting a) a polyisocyanate component with b) at least two compounds having hydrogen atoms active against them. isocyanates and c) catalysts, optionally in the presence of d) other adjuvants and additives, in which at least one of the components a) to d) are added organic or mineral hollow microspheres with an average particle size in the range of 5 to 200 μm and a density in the range of 0.1 to 0.8 g / cm3.

The coatings according to the invention are suitable for rollers or tubes such as those used in the steel, extraction or transport industry as well as in the paper industry. In addition, they can be manufactured with pipes with external coating for industrial as well as pipes with inner coating for the hydraulic transport of abrasive materials. If necessary, the surfaces to be coated with an adhesive medium must be provided beforehand. But tubes or other hollow bodies can also be manufactured according to the new method by coating a core that can be removed. In this case, a demoulding agent must be applied to the core or wrapped with a demoulding sheet. Finally, the new method can also be used to provide pipes with a thermal insulation envelope made of hard polyurethane foam. It has been indicated that the new method is not only suitable for the inner and outer coating of bodies with rotational symmetry, but also bodies can be coated having different diameters along their length and / or through their cross section. The method according to the invention is particularly suitable for the coating of pipelines in the field of marine drilling, especially for pipes with a depth greater than 500 m that are exposed to a pressure load greater than 50 bar and at a higher temperature of 120 ° C.

The reaction components are liquid reaction mixtures which react to give polyurethane plastics, which optionally have isocyanurate groups, solid or foamed, preferably hard. These are mixtures of organic polyisocyanates, preferably aromatic, with compounds having at least two hydrogen atoms active against isocyanates, in particular organic polydroxylic compounds, the polyisocyanates being used for the production of pure polyurethanes, in relation to the hydroxyl groups, in approximately equivalent quantities, and for the production of polyurethanes modified with isocyanurate groups in excess amounts. This means that the isocyanate index is generally in the range of 90 to 2,000, preferably 100 to 1,800. By "isocyanate index" is meant here the number of isocyanate groups of the polyisocyanate component per 100 hydroxyl groups of the polyhydroxy component. Suitable systems which react to give polyurethanes are described, for example, in DE-PS 16 94 138, while systems which react with polyurethanes modified with isocyanurate groups can be used according to DE-PS 25 34 247. The masses can be added customary adjuvants and additives, that is, catalysts for the addition reaction of isocyanates, such as dimethylbenzylamine, dibutyltin dilaurate or permethylated diethylenetriamine, catalysts for the trimerization of isocyanate groups of the type described in DE-PS 25 34 247, or fillers such as glass fibers, aluminum hydroxide, talc, chalk, dolomite, mica, heavy spar or wollastonite (CaSi03) . It is essential according to the invention, however, that in the reaction components, temperature-stable and pressure-resistant mineral and / or synthetic substances with a 0.5% microvoid structure up to a maximum filling are present, without generating them additional hollow spaces, referred to the total weight of the components of rección. The maximum filling is calculated as follows: Hollow body = density of the microvoid body Paparente = average apparent density of the microvoid body ppaR = density of the polyurethane matrix Hollow space = remaining space between bulk hollow bodies compacted to the maximum ESpaClO l ibre = Pcuerpo hollow - Paparente To achieve a yield of the matrix in the reaction, at least 1% by weight of matrix excess must be present with respect to the free space. Therefore, the following formula results as a maximum filler: Minimum PUR - quantity per 100 g of hollow bodies Minimum number of matrix = p ^ x (l / paparßntß ~ 1 P ueco body) x 1 01 x 100 The minimum PUR matrix calculated according to the above formula has a preferred characteristic value between 1,000 and 1,600. Preferably mineral microspheres are used. Particular preference is given to mineral microspheres in the density range of 0.1 to 0.8 g / cm 3 and of an average particle size of 5 to 200 μm, and a pressure resistance of more than 50 bar. Similar hollow bodies can be obtained commercially, for example, under the designation Q-CEL® (Fa Omya Gmbh) and Scothlite® Glas Bubbles (3M Deutschland GmbH). The essential additives according to the invention can be added to the polyisocyanate component as well as to the polyhydroxy component either previously or also directly before the reaction in the production of the casting compositions. The manufacture of the insulation layer is preferably carried out in tubes or according to the rotation coating method described in EP-A-636 467 or according to the usual casting in molds with the corresponding tube pieces as an insert. The insulation coatings produced according to the invention usually have a density of less than 0.9 g / cm 3, preferably a density of between 0.5 and 0.8 g / cm 3. It is advantageous if the coefficient of thermal conductivity for the insulation coatings produced according to the invention is less than 0.180 W / m.K. In addition the coatings of insulation according to the invention have a pressure resistance greater than 50 bar and a high thermal stability greater than 120 ° C.

EXAMPLES In the following Examples, both tube coatings according to the spin coating process and also according to the conventional casting method are described. General manufacturing indications The components A and B mentioned in the Examples were prepared separately before dosing by careful mixing of the individual components and practicing the vacuum below for their degassing. Dosing was carried out using special low-pulsation dosing pumps suitable for loads and needle valves in a special low-pressure mixing head. According to each procedure, the reactive mixture was applied to the tube either by means of a film nozzle (rotation coating) or by means of a round nozzle (classic casting) with a partially adjusted sleeve. The processing temperatures of the individual components were adjusted according to the viscosity at room temperature up to 70 ° C. The tubes always had room temperature, they were sandblasted and partially pretreated with a commercial adhesive medium. The molds were used both without heat as conditioned at 80 ° C to accelerate the hardening of the reactive polyurethane mixture. After demolding and respectively only after cooling to 35 ° C, the tubes were already deposited on the cover in a corresponding soft bed (prism of wood strips plus 40 mm thick of soft foam strips). The first physical tests were performed as soon as 24 hours after the casting process. 1) Insulation coating according to the rotation coating method In this case, the reactive polyurethane mixture was poured over the tube by rotating on itself through a film nozzle guided on the tube in the direction of the longitudinal axis. The advance of the nozzle was adjusted so that the desired coating thickness was achieved at constant ejection. Steel tube with an outside diameter of 230 mm Film nozzle 200 mm wide Eject of 12 1 / min = 8.4 kg / min Coating thickness of 45 mm Coating speed of 308 mm / min Density of the film layer insulation 0.7 g / cm3 Casting time 8-15 seconds Coefficient of thermal conductivity 0.14 W / mK Number of revolutions of the tube 28 rpm In the following Examples, both the polyethers used, the isocyanates as well as the characteristic index. Example 1 Component A "100 parts by weight polyether, index of OH 36, polyaddition of 83% of propylene oxide and 17% of ethylene oxide to trimethylpropane 2.0 parts by weight 50% zeolite in castor oil 1, 5 parts by weight activator, solution of alkaline acetate in diethylene glycol 40 parts by weight glass hollow microspheres, average density 0.32 g / cm3 Component B 150 parts by weight polyisocyanate with 31.5% NCO 3.0 parts by weight zeolite 50% castor oil 45 parts by weight hollow glass microspheres, average density 0.32 g / cm3 characteristic index 1.250 The pressure resistance test (test body: 100 mm edge length cube) at 200 bar in water at room temperature resulted after 24 hours of assay time a water absorption of less than 3 g for the entire test body. The thermostability test (200 x 100 x 10 mm test plates) resulted in storage of 4 months at 200 ° C the absence of variation visible some and no loss of properties. Example 2 Component A 100 parts by weight polyether, OH number 56, polyaddition of 100% propylene oxide to glycerin 2.0 parts by weight 50% zeolite in castor oil 3.5 parts by weight activator, acetate solution alkaline in diethylene glycol 35 parts by weight glass hollow microspheres, average density 0.32 g / cm3 Component B 150 parts by weight polyisocyanate with 31.5% NCO 3.0 parts by weight 50% zeolite in castor oil 45 parts by weight glass hollow microspheres, average density 0, 32 g / cm3 characteristic index 1,250 Example 3 Component A 100 parts by weight polyether, OH number 36, polyaddition of 83% propylene oxide and 17% ethylene oxide to trimethylpropane 2.0 parts by weight 50% zeolite castor oil 1.8 parts by weight activator, alkaline acetate solution in diethylene glycol 40 parts by weight glass hollow microspheres, average density 0.32 g / cm3 Component B Prepolymer of 150 parts by weight polyisocyanate and 12 parts by weight castor oil, Brazil-no. 1, NCO calculated 29% 3.0 parts by weight weight 50% zeolite in castor oil 45 parts by weight hollow glass microspheres, average density 0.32 g / cm3 characteristic index 1150 Example 4 Component A 100 parts by weight polyether, OH number 36, polyaddition of 83% oxide of propylene and 17% ethylene oxide to trimethylpropane 2.0 parts by weight 50% zeolite in castor oil 1.8 parts by weight activator, alkaline acetate solution in diethylene glycol 40 parts by weight glass hollow microspheres, average density 0.32 g / cm3 Component B Prepolymer of 162 parts by weight polyisocyanate and 13 parts by weight castor oil, Brazil-No.1, NCO calculated 29% 3.0 parts by weight 50% zeolite in castor oil 50 parts by weight glass hollow microspheres, average density 0.32 g / cm3 characteristic index 1,250 Example 5 Component A 100 parts by weight polyether, OH number 56, polyaddition of 100% propylene oxide to glycerin 2.0 parts by weight 50% zeolite in castor oil 3.5 parts by weight activator, solution of alkaline acetate in diethylene glycol 35 parts by weight glass hollow microspheres, density average 0.32 g / cm3 Component B Prepolymer of 150 parts by weight polyisocyanate and 12 parts by weight castor oil, Brazil-No.1, NCO calculated 29% 3.0 parts by weight 50% zeolite in castor oil 45 parts by weight glass hollow microspheres, average density 0.32 g / cm3 characteristic index 1.150 Example 6 Component .A 100 parts by weight polyether, index of OH 56, polyaddition of 100% of propylene oxide to glycerin 2.0 parts by weight 50% zeolite in castor oil 3.5 parts by weight activator, solution of alkaline acetate in diethylene glycol 35 parts by weight hollow glass microspheres, average density 0.32 g / cm3 Component B Prepolymer of 150 parts by weight, polyisocyanate and 13 parts by weight castor oil, Brazil-no. 1, calculated NCO 29% 3.0 parts by weight weight 50% zeolite in castor oil 50 parts by weight glass hollow microspheres, average density 0.32 g / cm3 characteristic index 1.250 2. Tube coating according to mold casting In this case a segment of pretreated tube was introduced in a mold conditioned thermally at 80 ° C treated with a release agent, the mold was closed, tilted 10 ° and in the deepest place It filled increasingly through a sleeve until the polyurethane reactant mixture flowed out of the mold at the highest point like a riser. Taking off the sleeve and removing the mixing head closed the mold on the projecting part and the mixing head with component A could be washed. Steel tube with an external diameter of 230 mm Coating length '56 cm Round nozzle of 22 mm diameter Ejection of 10 1 / min = 7 kg / min Thickness of 45 mm coating Density of the insulation layer 0.7 g / cm3 Casting time 140-200 seconds Coefficient of thermal conductivity 0.14 W / mK Filling time 135 seconds In the following examples both polyethers and isocyanates were varied used as well as the characteristic index. Example 7 Component A 100 parts by weight polyether, OH number 36, polyaddition of 83% propylene oxide and 17% ethylene oxide to trimethylpropane 2.0 parts by weight 50% zeolite in castor oil 0.6 parts by weight activator, alkaline acetate solution in diethylene glycol 40 parts by weight glass hollow microspheres, average density 0.32 g / cm3 Component B 150 parts by weight polyisocyanate with 31.5% NCO 3.0 parts by weight 50% zeolite in castor oil 45 parts by weight glass hollow microspheres, average density 0.32 g / cm3 characteristic index 1.250 Example 8 Component A 100 parts by weight polyether, index of OH 56, polyaddition of 100% propylene oxide to glycerin 2, 0 parts by weight 50% zeolite in castor oil 0.9 parts by weight activator, solution of alkaline acetate in diethylene glycol 35 parts by weight glass hollow microspheres, average density 0.32 g / cm3 Component B 150 parts by weight polyisocyanate with 31.5% NCO 3.0 parts by weight 50% zeolite in castor oil 45 parts by weight glass hollow microspheres, average density 0.32 g / cm3 characteristic index 1.250 Example 9 Component A 100 parts by weight polyether, index of OH 36, polyaddition of 83% of propylene oxide and 17% of ethylene oxide to trimethylpropane 2.0 parts by weight 50% zeolite in castor oil 0.6 parts by weight activator, solution of alkaline acetate in diethylene glycol 40 parts by weight glass hollow microspheres, average density 0.32 g / cm3 Component B Prepolymer of 150 parts by weight polyisocyanate and 12 parts by weight castor oil, Brazil-no. 1, NCO calculated 29% 3.0 parts by weight 50% zeolite in castor oil 45 parts by weight glass hollow microspheres, average density 0.32 g / cm3 characteristic index 1150 Example 10 Component A 100 parts by weight polyether, OH number 36, polyaddition of 83% propylene oxide and 17% ethylene oxide to trimethylpropane 2.0 parts by weight 50% zeolite % in castor oil 0.6 parts by weight activator, solution of alkaline acetate in diethylene glycol 40 parts by weight glass hollow microspheres, average density 0.32 g / cm3 Component B Prepolymer of 162 parts by weight polyisocyanate and 13 parts by weight castor oil, Brazil-No.1, calculated NCO 29% 3.0 parts by weight 50% zeolite in castor oil 50 parts by weight glass hollow microspheres , average density 0.32 g / cm3 characteristic index 1250 Example 11 Component A 100 parts by weight polyether, OH 56 index, polyaddition of 100% propylene oxide to glycerin 2.0 parts by weight 50% zeolite in oil castor 0.9 parts by weight activator, solution of alkaline acetate in diethylene glycol 35 parts by weight glass hollow microspheres, average density 0.32 g / cm3 Component B Prepolymer of 150 parts by weight polyisocyanate and 12 parts by weight castor oil, Brazil-No.1, NCO calculated 29% 3.0 parts by weight 50% zeolite in castor oil 45 parts by weight glass hollow microspheres, average density 0.32 g / cm3 characteristic index 1150 Example 12 Component A 100 parts by weight polyether, index of OH 56, polyaddition of 100% propylene oxide to glycerin 2.0 parts by weight 50% zeolite in castor oil 0.9 parts by weight activator, solution of alkaline acetate in diethylene glycol 35 parts by weight glass hollow microspheres, average density 0.32 g / cm3 Component B Prepolymer of 162 parts by weight polyisocyanate and 13 parts by weight castor oil, Brazil -n ° 1, calculated NCO 29% 3.0 parts by weight 50% zeolite in castor oil 50 parts by weight glass hollow microspheres, average density 0.32 g / cm3 characteristic index 1.250 It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (6)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property.

1. Process for the manufacture of insulation coatings having polyurethane and / or polyisocyanurate groups for hollow bodies by reacting a) a polyisocyanate component with b) at least two compounds having hydrogen atoms active against isocyanates and c) catalysts, optionally in the presence of d) other adjuvants and additives, characterized in that organic or mineral hollow microspheres having an average particle size in the range of 5 to 200 μm and a density in the range of at least one of the components a) to d) are added. range from 0.1 to 0.8 g / cm3.

2. Process according to claim 1, characterized in that mineral hollow microspheres are added.

3. Process according to one of claims 1 to 2, characterized in that hollow microspheres with a pressure resistance greater than 10 bar are added.

4. Procedure according to one of the claims above, characterized in that the hollow bodies are tubes.

5. Insulation coatings having polyurethane and / or polyisocyanurate groups for hollow bodies by reaction of a) a polyisocyanate component with b) at least two compounds having hydrogen atoms active against isocyanates and c) catalysts, optionally in the presence of d) other adjuvants and additives, characterized in that the insulation coating contains hollow microspheres with an average particle size in the range of 5 to 200 μm and a density in the range of 0.1 to 0.8 g / cm 3.

6. Use of an insulation coating according to claim 5 for the coating of pipes in the field of marine drilling.