DE940787C - Floating body made of polyurethane foam - Google Patents

Description

Floats made of polyurethane foams The manufacture of floats from plastics in the compression process or from foams on a plastic basis, the It is known to have the same specific weight over the entire cross section.

It is also known that such foam bodies can be produced by subsequent pressing to give a higher volume weight in the mantle zone. It is also known metallic To subsequently fill hollow bodies or hollow bodies made of plastic with foams, so that they become unsinkable and the foam filling makes them thin-walled External structures are supported against strong external pressures.

It has now been found that the strength and bearing capacity of such Floats still increase significantly and at the same time the process for their manufacture can simplify if you manufacture these floating bodies in such a way that the Foaming of the polyurethane components takes place in a form and this measures be taken through which a foam is obtained, its specific weight decreases from the sheath to the core.

Such Schwirnmkörper can z. B. with a lightweight core from Volume weight 10 to 100 kglm3 and a load-bearing shell zone with a volume weight of 200 up to Soo kg / m3 can be provided in one operation.

The invention preferably includes polyurethane foams with more or less open pores or with closed pores (cells) based on that in molds at normal temperature or with additional supply of heat made of metal, plastic, wood, concrete or in sand molds.

There are preferably fast and liquid blowing foam approaches selected, which is produced in suitable and known mixing apparatus and in the form can be poured or injected in doses.

In order to achieve a stable, watertight mantle zone in the Molded body, the mold provided with release agent is first made with a fleece Glass fibers or metal threads or laid out from synthetic or natural fibers, this by means of a foaming pressure of the buoyant which is determined by the choice of recipe Polyurethane foam mixture up to the mold wall from the foam mixture is completely penetrated, creating a foam body after the reaction has ended with a low density in the core (e.g. Rg. = 10 to Iookglm3) and a very high Volume weight (e.g. Rg. = 200 to 800 kgim3) arises in the jacket zone because the foam process is severely hindered by the fleece and thus a considerable increase in the specific Weight occurs. The strength of the mantle zone can vary depending on the endurance External pressure or, depending on the size of the float to be made, from 2 to 30 mm thickness can be formed by changing the thickness of the submitted fleece to the desired Construction is chosen accordingly and consist of one or more layers of the same Structure or different density can exist. As fiber fleeces are particularly suitable three-dimensional mechanically bonded nonwovens made of glass fibers, polyurethanes, Perlon, acetyl cellulose, leather fibers, horsehair or other technical fibers. Further metal mesh or metal fleece are suitable. It is also possible to have combinations to use the above mentioned fleece or fabric, if zones of higher strength be desired.

A pretreatment of the fleece with the foam process. strongly accelerating Activators preferably with tertiary amines is often useful, whereby the Homogeneity of the jacket zone and the increase in the specific weight of this jacket zone is promoted.

It is possible according to the invention to have fittings of all types in the floating body to be attached, with this already inserted into the mold before the foaming process and through the foam process are completely enclosed and anchored. But it is also possible to retrofit these fittings, with the edge zones through if necessary additional fleece inlays are reinforced or possibly even deep in the Fitting parts penetrating molded bodies are located under the fixed jacket zone Foam core with a lower volume weight due to the local inlay of firmer filling blocks or dowels, e.g. B. made of heavy foams or wood or metal, is reinforced. These fillers are laid out with the fleeces before the foaming process Form mounted so that it is completely enveloped by the expanding foam mixture and be firmly anchored as soon as the foam reaction has ended.

To improve the water resistance of the float it is possible according to the invention, before the nonwovens are introduced into the one provided with a release agent Mold a pre-injection of the mold with a suitable reactive plastic and only then to assemble the fleece in the mold.

Reactive mixtures are suitable as plastic pre-injection from polyesters containing hydroxyl and carboxyl groups and isocyanates or polyester isocyanates or polymerizable plastic systems, preferably from copolymers of Polyesters made from maleic acid, phthalic acid and glycol with styrene or a combination thereof with polyisocyanates or vulcanizable, preferably heat-sensitive rubber-latex systems, Polyethylene dispersions or paints of all kinds, fresh or cured Foaming can be done. This pre-injection also has the advantage that the The nonwovens to be inserted can be better fixed so that they can be used during the foaming process cannot be pushed off the mold wall and in the desired jacket zone to lie down.

Furthermore, the invention also allows the additional on the outside Use of fabrics made with polymerizable stabilized polyester peroxide systems are impregnated, which are more reactive when suitable. Polyurethane foam mixtures for final polymerization due to the foaming pressure and that which occurs with these foam mixtures high heat of reaction, which can rise to 180 "C. The foaming pressure can rise up to 5 atm. Very high-strength outer skins can be produced using this method are also generated, the decreasing in specific weight towards the core Foam are so strongly supported that they have excellent dent resistance own.

The use of pre-impregnated, stabilized polyester glass fabrics can also be done in such a way that one first intensifies the pure surface Manufactures foam core, which is now used to achieve an even with high external pressures waterproof cover layer is wrapped with foils of such prepared glass fabric, which are subjected to a heat treatment (Ioo to I20 "C). In the same way the foam core can be wrapped with impregnated glass fabrics, wherein the impregnation of the fabric with polyester resins or polyurethane combinations is made shortly before the sheathing of the foam core.

According to the invention it is also possible to produce hollow bodies, by having a previously produced thin-walled hollow body made of metal or plastic foamed in the process described above. It is also possible to use such hollow bodies to produce from half or partial shells, the half or partial shells in the Process according to the invention are made and for final assembly by means of glue are preferably combined on a polyurethane basis, the adhesive zones in itself reinforced with fibers made of glass, metal or synthetic fibers can.

The invention also allows the core of fully foamed bodies also other materials made of metal tall, wood or plastic to be foamed, to possibly influence the weight or the price of the floats or the To adapt the intended use.

The invention is further explained in FIGS.

Fig. I and 2: I and 2 are mold halves that are covered with a fleece 3 are, which is possibly well fixed in the form by a pre-injection 4. To Entry of the foam mixture into one mold half and closing of the mold halves occurs a body 6, which consists of the pre-molded, dense outer skin 7, the jacket zone 8 Heavy foam reinforced by fibers and the foam coreg of low specificity Weight exists.

The installation of a fitting 10 in a reinforced fleece inserts II highly consolidated zone is shown in Figs. 5 and 6, with the core reinforcement also in other ways than dowels 12 z. B. could be made of wood that of the specifically light foam core I3 is fully foamed. Floating body as a hollow body Figs. 7 to 9 show, with the previously produced hollow body 15 in the with Fleece I6 occupied form 17 is mounted and foamed. From half-shells I8 can the hollow body can be produced by gluing 19.

The constructions according to the invention are suitable for floating bodies for deep sea fishing, floats for military use, such as mines in all Sizes, for boat constructions in fully foamed construction or in shell construction, for lifebuoys, rafts and life jackets.

Example I Fast-blowing polyurethane foam mixtures are found for the foam process following composition application: 100 parts by volume of saturated polyester, 3 parts by volume Silica chalk, 3 parts by volume of activator, 65 parts by volume of tolylene diisocyanate or 100 Parts by volume of saturated polyester, 3 parts by volume of chalk, 3 parts by volume of activator, 70 parts by volume of tolylene diisocyanate.

The polyester is preheated to 60 ° C during the production of the mixtures and suddenly entered into the mold, which has been preheated to 40 to 50 ° C. The foam process is completed in about 10 minutes.

The pre-injection of the mold for the attachment of the spatial fiber fleece takes place with the following mixture: 100 parts of maleic acid glycol polyester, 150 parts Titanium dioxide, 6 parts of a peroxide paste (r: 1 in dibutyl phthalate), 0.07 part of dimethylaniline.

About 2 kg for 1 m2 are sufficient for the surface treatment.

This mixture is diluted to sprayability with methylene chloride and first applied half per 1 m2 using a spray gun so that a first top layer is created, which reacts completely under infrared radiation is brought. The remainder of the amounts described above are then entered Foam approaches also using a spray gun in diluted with methylene chloride State. The spatially matted fleece is pressed onto the still fresh injection. Then the foaming process takes place immediately, in which the fast-floating process takes place under high pressures and temperature-responsive foam penetrates the nonwoven fabric at the same time the second mold injection hardens.

Example 2 A solution is used to form the homogeneous top layer made of an isocyanate-extended polyester, which is produced by extending a linear polyester made from adipic acid glycol using hexamethylene diisocyanate is generated and contains accelerator components. This polyester isocyanate accelerator system is dissolved in methylene chloride and degreased using a spray gun Registered shapes and then placed the fleece.

The foaming process is carried out as indicated in Example I.

Claims (5)

PATENT CLAIMS: I. Floating body made of polyurethane foams, thereby characterized in that it contains a nonwoven fabric on its surface and the specific The weight of the foam decreases from the shell to the core. 2. Floating body according to claim 1, characterized in that im Foam core of the float fillers, such as porous materials from other synthetic materials, Metal, homogeneous plastics, plaster of paris, concrete, etc., are contained in foamed form. 3. A method for the production of floating bodies according to claim 1, characterized in that in the mold used to produce the molded body Nonwovens or combinations of nonwovens made from glass fibers, from metal threads or from synthetic or natural fibers are inserted and then the shape with the reactive, foam-forming mixture of polyurethane components and activators filled will. 4. The method according to claim 2, characterized in that fiber webs be used that are wetted with substances that accelerate the foam process. 5. The method according to claim 3 and 4, characterized in that before Insertion of the fleece, the mold provided with release agent with reactive plastic systems is sprayed out, such as mixtures of hydroxyl and / or carboxyl groups Polyesters with polyisocyanates or their reaction products or polymerizable Substances preferably made of unsaturated polyesters and vinyl compounds with additives of peroxides or their combination with polyester isocyanates or heat-sensitive Rubber-latex systems or polyethylene dispersions.