DE19722551A1 - Use of injection moulding process to produce plastic components with areas having different properties and injection process - Google Patents

Abstract

In an injection moulding process for manufacturing plastic parts with two inseparable areas having different physical and/or chemical properties, in particular different colours and mechanical properties, both parts are moulded in a single cycle, the different plastics being injected at different times and/or into different areas of the mould.

Description

The invention relates to a method for producing plastic parts with spatially distinguishable areas, each different have physical and / or chemical plastic properties, according to the preamble of claim 1.

Plastic parts of the type in question can be found in particular, however by no means exclusively, in motor vehicles, for example as an exterior mirror housing, use. It is often made of aesthetic green the required that the plastic parts provide a surface are that correspond in color to the surface of the vehicle that the Surface is particularly scratch-resistant and weatherproof and at the same time The core of the plastic part has particularly good mechanical properties ten, especially high impact strength.

Such plastic parts are usually made in a multi-stage process Process manufactured. First, the parts are not made from one colored plastic, for example by injection molding and then painted in the desired color. The function of the The mechanically loadable core takes over the plastic that The paint fulfills the surface function with the corresponding color.  

Both materials can be selected according to their specific requirements cal function can be adjusted. Since doing so before the actual painting the parts must be degreased and ionized regularly this known manufacturing process is expensive and requires also long lead times.

From DE 296 10 374 U1 there is also an outside mirror for motor vehicles known, the housing of a solid-colored thermoplastic represents is. This allows an adjustment to the color of the vehicle done without the need for painting, but are colored plastics in comparison to conventional plastics really expensive. In addition, the construction of the component from a single forces a compromise between good surface properties on the one hand and good mechanical properties of the component core on the other side.

Based on this state of the art, it is the task of the present ing invention to provide a method, components in an injection molding process, the different areas, in particular the Surface and the core, specific to the requirements in the below different areas can be matched, creating higher quality Components can be manufactured at lower costs.

This task is accomplished by a method according to the teaching of the patent spell 1 solved.

Advantageous embodiments of the invention are the subject of the Unteran claims.

In the method according to the invention plastic materials are used different properties temporally and / or spatially offset in the Mold injected. This is done in a single injection molding process. It So a component is not injected in a first form and then in overmoulded in a second mold, but is manufactured in one graduated but coherent two-component injection molding  process. Due to the spatially or temporally offset injection of the Various plastic materials in the mold ensure that the Plastic materials do not mix completely in the mold. It This creates areas of the component in which a plastic material in the is essentially in homogeneous form and thus the corresponding has specific plastic properties, whereas art material materials mix in the border areas and thereby are inseparable. The result arises in one single injection molding process a component with several different Property zones by selecting the appropriate starting material rialien can be adapted to the requirement profile of the component and inseparable through mixing or accumulation in the border areas are connected to one another in cash. In other words, that is invented process according to the invention in a two-component injection molding process Manufacture of components with the structure of a composite material possible.

It is particularly advantageous to use the plastic materials with each different properties layered in front of the injection opening melt and one after the other into the injection molding process Inject form. This can be achieved in particular that in the screw of an injection molding machine one after the other different Plastic materials are melted and then before the Snail tip layered in the melting phase. Will the Injection process opened by advancing the screw tip, the different layers of the melt one after the other into the mold pressed. By designing the shape and the injection box accordingly channels can be achieved that the corresponding component areas of the desired plastic materials are formed.

It is particularly favorable to use the method according to the invention to make art fabric parts with a multi-layer, in particular two-layer, Manufacturing structure, one of the layers of a solid color Plastic is made. The solid-colored plastic can do the outside  form the surface of a component, thus allowing the color to be adjusted of the component to the color of, for example, a motor vehicle without the entire component made of colored plastic or after the injection molding would have to be painted.

Because colored plastics in comparison to conventional art fabrics are relatively expensive and the aesthetic color impression of a component is essentially independent of the thickness of the color layer, should only an outer, thin layer of the plastic part made of a solid color Plastic material exist.

It is particularly suitable as the base material for the colorable plastic ders PMMA (polymethyl methacrylate) or PC (polycarbonate), because this Plastics can be colored very well or inexpensively and above have high-gloss properties. That PMMA and PC are only one have low impact strength, which is why these materials in many Cases for plastic parts made from a single plastic material manufactured, cannot be used, plays with the inventor Process according to the invention does not matter because the required impact strength of the component by a second material component in the component core can be reached.

To achieve good impact values at low cost the component core can be manufactured particularly cheaply from ABS.

However, it is also due to the manufacture of the component core from recycled Thinking plastic. Legal requirements in particular oblige the Manufacturers of motor vehicles to use a minimum percentage of recycled plastic material. Common recycled plastic materials have very useful mechanical properties. A stake Such materials in the surface area are usually not possible Lich, because these materials are difficult to color and have poor surface properties.

Nowadays, high-gloss component surfaces are often required  through plastics with sufficient properties regarding their me mechanical resilience and / or their colorability is not achieved can be. If such high-gloss surfaces are required, For example, components made of fully colored plastic must can be repainted. Repainting can be omitted if the core of the plastic part made of a solid-colored plastic material is produced and in the process according to the invention with a Layer of transparent plastic, especially high-gloss transparent rent PMMA or PC, is covered.

The transparent plastic should be a means of protecting against flows by light, especially UV radiation, added will. The UV radiation is already in the top transparent Intercepted plastic layer, embrittlement will be the underlying effectively prevents the material areas and other measures to Protection of the component against embrittlement, such as the additives stabilizers, can be omitted or reduced.

According to the invention, it is also possible to use the transparent plastic Pigments, especially metal particles, to achieve a Metallicef admixture. The plastic parts can also be colored on the upper area to be adjusted, which are covered with metallic paint, as in Motor vehicles are becoming increasingly common.

According to the invention, it is also possible to use components with a three-layer manufacture structure that has a core of a tough material, a Cover layer made of solid-colored plastic and a surface layer have made of transparent plastic. This three-layer composite construction allows the economical production of mechanically high beans noticeable components, the color of which can be adapted and the one have a high-gloss surface in a single injection molding process. The individual component areas can be selected by suitable selection Plastics can be adapted to the requirement profile.  

Because in the automotive industry in particular, components in a variety of colors, it makes sense to use components in this area a uniform core and with different colors To produce surface layers in the method according to the invention. A transparent surface layer is then applied in a separate, the spraying process subsequent operation according to the invention brings. There are all types for applying the transparent layer of coating methods conceivable, in particular, the blank can in a second injection process with a transparent plastic be injected.

Are special surface structures or special color effects such as For example, a metallic effect, may also be required before implementation tion of the spraying method coating or De Kormaterial be inserted into the mold, which during the spray casting process is at least partially overmolded. Through the spray process creates an inseparable connection between the coating or Decorative material with the rest of the component body.

The method according to the invention is particularly suitable for the production of parts of motor vehicles. All parts, which are also normally produced by injection molding, in particular at low cost in colored and / or high-gloss designs can be produced by the method according to the invention. Especially is here on door handle units with handle element, frame element and Recessed grips, as well as mirror housings, mirror caps and moldings think. Because components for the automotive industry are mass-produced are the higher investment costs for more complex tools quickly amortize designs and more expensive machines.

Claims (14)

1. A process for the production of plastic parts from, in particular, injection-moldable plastics which have at least two unreleasably connected, spatially distinguishable areas with different physical and / or chemical plastic properties, in particular with different colors and mechanical properties, characterized in that the plastic parts are produced in an injection molding process, the plastic materials with different properties being injected into the mold at different times and / or in different locations. 2. The method according to claim 1, characterized, that plastic materials with different properties the injection opening are melted and layered on then be injected into the mold one after the other.   3. The method according to claim 1 or 2, characterized, that the plastic parts produced a multilayer, esp special two-layer, have structure and one of the layers a solid-colored plastic. 4. The method according to claim 3, characterized, that only an outer thin layer of the plastic part from one solid colored plastic. 5. The method according to claim 3 or 4, characterized, that the color-through plastic consists of PMMA or PC. 6. The method according to any one of claims 1 to 5, characterized, that the plastic parts produced a multilayer, esp special two-layer, have structure and one of the layers impact-resistant plastic, in particular ABS. 7. The method according to any one of claims 1 to 6, characterized, that the plastic parts produced a multilayer, esp special two-layer, have structure and one of the layers a recycled plastic.   8. The method according to any one of claims 1 to 7, characterized, that the plastic parts produced a multilayer, esp special two-layer, have structure and the outermost layer made of a transparent plastic, especially high-gloss PMMA or PC. 9. The method according to claim 8, characterized, that the transparent plastic means to protect against influences by exposure to light, in particular UV radiation. 10. The method according to claim 8, characterized, that the transparent plastic pigments, especially metal par article, to achieve a metallic effect. 11. The method according to any one of claims 1 to 10, characterized, that the plastic part has a three-layer structure, with a Core layer, a solid colored surrounding this core layer Layer and a transpa surrounding the solid-colored layer pension layer. 12. The method according to claim 11, characterized, that only the core layer and the solid-colored layer in one Injection molding are made together and the transpa pension layer applied in a subsequent work step, in particular overmolded.   13. The method according to any one of claims 1 to 12, characterized, that the form before the spraying process with additional coating or Decorative material is provided after the injection molding process is inseparably connected to the plastic part produced. 14. Application of the method according to one of the preceding claims for the production of parts of a motor vehicle, in particular door handle units with handle element, frame element and recessed grip, and mirror housing, mirror caps, moldings and the like.