Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/34—Applying different liquids or other fluent materials simultaneously
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/04—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to gases
  • B05D3/0493—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to gases using vacuum

Definitions

• the invention relates to a method for producing a cured plastic compound based on a two- or multi-component reactive system and a reactive system coordinated therewith.
• coatings can be applied to substrates, in particular lacquer or adhesive coatings, as is the case, for example, in FIG EP 0 590 975 A1 is described.
• Two- or multi-component reactive systems are also used to produce molded bodies with composite materials, in particular with fiber composite materials.
• the invention is based on the object of providing a method for coating and / or painting vehicle parts with which, in the case of complex shapes of the vehicle parts, even areas that are difficult to access can be coated or painted in good quality.
• the disclosure also relates to a method for producing cured plastic compounds based on a two- or multi-component reactive system of the type described at the outset, with which a cured plastic compound with improved properties is obtained.
• a two- or multi-component reactive system of the type mentioned the conditioning of the reactive system to specified reaction conditions and the subsequent reduction in the ambient pressure of the reactive system lead to a release of the microencapsulated component and, associated therewith, to the start of the curing reaction.
• a cured plastic mass can be formed in a very homogeneous manner over the cross section of the plastic mass, since uniform starting conditions for the curing reaction can be achieved in practically all parts of the volume of the plastic mass at the same time.
• Another advantage of the present invention is in particular that the curing reaction proceeds uniformly regardless of the geometry of the product to be formed from the cured plastic compound, in particular also in areas that are difficult to access.
• areas of the product that are difficult to access represent, for example, those sections of the product which, due to the formation of shadows and / or covering, cannot or can only be reached with difficulty by the curing radiation.
• areas of the product that are difficult to access are those sections of the product that are at a certain distance from a point of introduction of heat and that are heated only slowly or with a time delay due to a low thermal conductivity and / or a high mass of the product.
• the pressure reduction can be sudden, i.e. in the range from about 10 to about 500 milliseconds, or else gradually, e.g. in the range of several minutes (e.g. approx. 1 to approx. 5 min). In both cases, a sufficiently uniform release of the (micro) encapsulated component and subsequently a homogeneous curing of the plastic compound can be achieved.
• adjustable pressure differences are in the range from approx. 0.01 bar to approx. 0.9 bar.
• the temperature of the reactive system in particular to remove residual solvents and / or to allow the curing reaction of the plastic compound to proceed more quickly.
• the viscosity also decreases, which leads to an increase in the speed of pressure propagation in the plastic compound.
• This can be implemented as a partial step of the conditioning process, so that optimal reaction conditions are given at the beginning of the curing reaction. If it takes a certain amount of time to reach a uniform temperature in the plastic compound, the reduction in the ambient pressure can be postponed until a temperature equilibrium is reached, so that the curing reaction starts under the same conditions in all parts of the volume.
• the method according to the invention it is possible, as part of the conditioning, in particular when setting a system temperature that is higher than room temperature, to increase the ambient pressure, if necessary, in order to counteract the expansion of the microcapsules and thus premature breaking of the microcapsules and to start the hardening reaction of the Plastic compound to avoid before reaching a uniform temperature distribution in the same. Only then is the pressure reduced, starting from the higher ambient pressure, so that the curing reaction is then started with a reactive system conditioned at a higher temperature, which then proceeds faster.
• this in particular avoids warping and an unaesthetic appearance of the component as a result of curing processes that take place at different speeds or that begin at different times.
• the method according to the invention is also particularly suitable for the mass production of products in which composite materials are used.
• a two- or multicomponent reactive system after a two- or multicomponent reactive system has been provided, it is subjected to an increased temperature and a changing ambient pressure in an autoclave, for example applying an overpressure, an ambient pressure and / or a vacuum determined by the reaction conditions.
• pressure shock waves can also be provided, which can contain both short-term pressure increases and short-term pressure decreases in rapid succession.
• a reactive system with an encapsulated reactive component, in which this is selected from initiators, catalysts and / or accelerators for the curing reaction.
• the microcapsules preferably contain radicals such as those formed when UV photoinitiators are exposed to UV radiation. Long-lived and / or stabilized radicals are particularly suitable.
• the properties of the reactive system during curing can be optimized for the particular application.
• this also enables the release of radicals by means of light, in particular UV radiation, which can be integrated into the method according to the invention as a substep of the conditioning process, or can be done when the two- or multi-component reactive system is provided, so that the conditions for production the free-radical encapsulated component can be selected in a simple manner in such a way that the component is fully activated and shadowing effects, as in the prior art, are avoided.
• light in particular UV radiation
• the effect of the release of the microencapsulated component can in a variant of the method according to the invention during or after the reduction of the ambient pressure by means of the use of sound waves, in particular infrasound in a frequency range of about 0.2 Hz to about 10 Hz or Ultrasound in a frequency range from approx. 20 kHz to approx. 500 kHz can be supported.
• sound waves should, for example, act on the environment of the reactive system in the range of approx. 0.01 Pa to approx. 100 Pa.
• the method described above is also particularly suitable for plastic compounds that represent a composite material, are used as paint or generally as a coating material, or also for plastic compounds that represent a three-dimensional plastic component.
• the reactive system is injected into an injection mold.
• the plastic compound is applied by spraying or spraying or is placed in the mold in the form of pre-fabricated fabrics (so-called "prepregs").
• prepregs are resin-impregnated mats or panels in which the reactive system is in the form of a solidified melt.
• the method is suitable for plastic compounds that represent a coating on a surface of a substrate, the substrate according to the invention being a motor vehicle body or a part / module of a motor vehicle body.
• Modules of a motor vehicle body can be the frame (“spaceframe”), frame parts and add-on parts such as roof, hoods, fenders, side parts, doors and various small parts.
• the reactive system is applied to the substrate in a dip-coating process, while according to another preferred variant, application is carried out by spraying or spraying.
• the reactive system when the reactive system is provided, the system is first mixed with essentially all components with the exception of the microencapsulated component and only then is the microencapsulated component added to the reactive system. This is recommended, for example, when an activated reactive component is used, in particular in the form of a long-lived radical.
• the reactive system used can be a dispersion (soft, deformable, mobile microcapsules in liquid) or a suspension (solid, hard microcapsules in liquid) or a combination of soft and hard microcapsules in a liquid.
• the reactive system is present in a mixture of powdery components and the microencapsulated component and is accordingly processed as a powdery solid mixture.
• the activation of the microencapsulated component can be carried out before or also during the addition to the reactive system.
• the activation of the microencapsulated component can be implemented as a conditioning substep.
• the disclosure also relates to two- or multi-component reactive systems, in particular for use in one of the above-mentioned methods, in which the reactive coating system comprises two or more reactive components, at least one of the components being in an encapsulated form, the encapsulation of which can be destroyed by reducing the pressure.
• the encapsulated component of the reactive systems according to the invention comprises in particular an initiator, a catalyst and / or a reaction accelerator for the curing reaction of the reactive system.
• the microcapsules preferably contain radicals such as those formed when UV photoinitiators are exposed to UV radiation.
• the two- or multi-component reactive systems are designed as a paint formulation.
• Another preferred form of the two- or multi-component reactive system according to the invention is that of a composite material, the material in particular comprising oriented or non-oriented short, long or continuous fibers, selected from the group of glass fibers, carbon fibers, ceramic fibers, natural fibers and / or polymer fibers.
• particularly preferred reactive systems include additives, in particular in the form of colorants and fillers (pigments, dyes, etc.) and auxiliaries (leveling aids, plasticizers, light stabilizers, etc.).
• the reactive systems according to the invention preferably use microcapsules of an inorganic compound based in particular on SiO 2 , with an average wall thickness of the encapsulation of approx. 4 to approx. 100 nanometers, in particular approx. 10 to approx. 75 nanometers, is chosen. With such wall thicknesses, it is ensured that the reactive system can be applied as a coating with the usual technical aids, used as a casting compound in the manufacture of three-dimensional objects or also used in the processing into composite materials.
• an upper limit of the wall thickness of preferably approx. 50 nanometers should be observed so that it is sufficient with economic means Pressure reduction can be represented, which lead to the opening of the microcapsules and release of the encapsulated component.
• the encapsulation is based on an organic compound (polymer shell), in which case average wall thicknesses in the range from approx. 10 to approx. 50 nanometers are preferred.
• the encapsulated component can be safely handled in the reactive system in the typical method for applying the reactive system as a coating on substrates and / or during processing into composite materials.
• the encapsulation can be made from, in particular, organic materials based on waxes or gelatin.
• the microcapsules In order to ensure that the microencapsulated component is distributed as uniformly as possible in the reactive system and thus uniform reaction conditions in all parts of the volume, it is recommended to use the microcapsules with an average capsule diameter of approx. 20 nm to approx. 10,000 nm, in particular approx. 20 nm to approx 1,000 nm.
• a propellant is enclosed in the microcapsule in addition to the actual reactive component.
• Propellants in particular solvents, with a vapor pressure of approx. 20 mbar or more at 20 ° C. are preferred.
• the reactive systems according to the invention can be designed as a pasty mass.
• the reactive system according to the invention is designed as a curable melt.
• Two- or multicomponent reactive systems for the processes of Examples 1 to 6 below can be derived, for example, from the in EP 1 497 338 B1 Develop described reactive systems, to which reference is made here in full. In particular, the EP 1 497 338 B1 to get expelled.
• the photoinitiators are added to the reactive systems in accordance with the present invention in microencapsulated form.
• the photoinitiators are activated by irradiation while still in the microencapsulated state and the reactive system is then applied to the substrates to be coated or injected into corresponding molds.
• the activated photoinitiators are then released from the microcapsules, as is described in detail below in Examples 1 to 6.
• a workpiece for example a motor vehicle body or a motor vehicle module, is provided with a lacquer layer, for example a clear lacquer.
• the workpiece is then placed in a chamber and optionally exposed to a slight negative pressure of approx. 0.8 to 0.9 bar (absolute) for approx. 10 minutes, whereby the remaining solvent escapes from the paint film and thus the paint film dries. Then suddenly (by opening a valve to a parallel chamber under vacuum) the pressure in the chamber is reduced to approximately 0.2 bar to 0.1 bar (absolute).
• the microcapsules contained in the reactive system of the paint film break within a short time and the hardening component is released and causes the paint film to cure within a short time (10 seconds to 2 minutes).
• a workpiece e.g. a motor vehicle body or a motor vehicle module
• a layer of paint e.g. a clear lacquer.
• the workpiece is then placed in a paint dryer, where the workpiece is exposed to a temperature that is 40 to 120 K higher than the ambient temperature for approx. 5 to 15 minutes, whereby the remaining solvent escapes from the paint film and the paint film dries.
• the workpiece is then placed in a chamber and within a few minutes or seconds (by opening a valve to a parallel chamber under vacuum) the pressure in the chamber is reduced to below 0.1 bar.
• the microcapsules contained in the reactive system of the paint film break and the hardening component is released and causes the paint film to cure within a short time (10 seconds to 2 minutes).
• a workpiece for example a motor vehicle component or a motor vehicle module
• a lacquer layer for example a clear lacquer.
• the reactive system of the clear lacquer composition is treated by means of UV radiation during the application of the clear lacquer to the component or module and its microencapsulated component is activated.
• the workpiece is brought into a paint dryer, where the workpiece is exposed to a temperature that is 40 to 120 K higher than the ambient temperature for approx. 5 to 15 minutes and / or a slight negative pressure of approx. 0.8 to 0.9 bar (absolute ), whereby the remaining solvent escapes from the paint film and thus the paint film dries.
• the workpiece is then placed in a chamber and within 2 minutes or suddenly (e.g. by opening a valve to a parallel chamber under vacuum) the pressure in the chamber is reduced to approx. 0.1 bar (absolute), ie by a pressure difference of approx. 0.7 bar to 0.8 bar compared to the previously set pressure level or by a pressure difference of 0.9 bar compared to atmospheric pressure.
• the microcapsules contained in the reactive system of the paint film break and the activated hardening component is released and causes the paint film to cure within a short time (10 seconds to 2 minutes).
• a two-component or multi-component plastic compound (reactive system) is injected into a mold with or without an inserted fiber reinforcement part. Then (or even during injection) the workpiece formed by the tool shape is heated in the workpiece shape by 20 to 80 K compared to the original temperature and at the same time the ambient pressure is increased proportionally to the temperature increase up to a maximum of 10 bar (absolute). After the uniform heating, the workpiece in the tool mold is suddenly lowered again to atmospheric pressure conditions. The microcapsules contained in the plastic mass break and the hardening component is released and causes the plastic or composite part to harden within a short time (10 seconds to 2 minutes).
• a two- or multi-component plastic compound (reactive system) is injected into a mold with or without an inserted fiber reinforcement part. Subsequently (or even during the injection process) the workpiece formed by the tool shape is exposed in the workpiece shape to an ambient pressure (negative pressure) that is reduced compared to standard conditions, in particular atmospheric pressure. After reaching the maximum negative pressure of approx. 0.1 bar or less, the microcapsules contained in the plastic compound break and the hardening component is released and causes the plastic or composite part to harden within a short time (10 seconds to 2 minutes).
• a two-component or multi-component plastic compound is placed in a mold with or without an inserted fiber reinforcement part (Reactive system) injected.
• the plastic compound in the supply line is irradiated with UV radiation for a maximum of 1 minute, which activates the components contained in the microcapsules.
• the workpiece formed by the tool mold is exposed to a negative pressure in the workpiece mold. After reaching the maximum negative pressure of approx. 0.1 bar or less, the microcapsules contained in the plastic compound break and the hardening component is released and causes the plastic or composite part to harden within a short time (10 seconds to 2 minutes).

Landscapes

• Application Of Or Painting With Fluid Materials (AREA)
• Paints Or Removers (AREA)

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• 2011
  • 2011-06-06 DE DE102011050871A patent/DE102011050871A1/de not_active Withdrawn
• 2012
  • 2012-06-05 WO PCT/EP2012/060625 patent/WO2012168258A2/de active Application Filing
  • 2012-06-05 EP EP12726101.4A patent/EP2718025B1/de active Active
  • 2012-06-05 CN CN201280028042.5A patent/CN103608126B/zh not_active Expired - Fee Related

Non-Patent Citations (1)

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