DE102007028076A1 - Composite material manufacturing involves applying adhesion-promoting agent on plastic for connecting metallic substrate, where adhesion-promoting agent has two different binder systems - Google Patents

Abstract

Composite material manufacturing involves applying an adhesion-promoting agent on the plastic for connecting metallic substrate. The adhesion-promoting agent has two different binder systems. The solid particle of the binding metal system, which is lying in the cross linked adhesion-promoting agent distributes in liquid binder systems. The binder system is dehumidified or cross linked after the adhesion-promoting agent.

Description

The The invention relates to a method for producing stable metal-plastic injection-molded composites characterized in that to be connected to the plastic metallic substrate is applied to a primer, the two contains different binder systems. In the bonding agent are crosslinkable solid particles of the binder system II in the liquid binder system I distributed before. After this Adhesive agent application is dried / crosslinked binder system I, wherein the reactivity of binder system II is substantially preserved.

The metallic substrate to be bonded to the plastic becomes common referred to as "insert", as it is usually before the Injection molding into the tool "inserted" is. Depending on the geometry is called the production of the hybrid component, for example as injection molding, Overmolding or back injection.

With increasing demands on the load capacity of components in machines and facilities are increasingly being combined into materials, which are not cohesive without the use of adhesion promoters and can be connected firmly.

For the production of resilient, media-dense injection-molded composites must In addition, the adhesion promoter has certain requirements meet the processability.

At the An-, Um- or injection molding of a substrate is a on the Surface high adhesion adhesive layer and at the same time exposed to mechanical stress.

The on the substrate applied adhesion promoter coating must for One with sufficient adhesion and durability remain on the substrate surface, d. H. that neither a detachment from the substrate surface still a Flowing away or thermal degradation may occur; to the Others should still have enough structures which can form a liability to aufzuspritzenden plastic.

• – Thermoplastische Kunststoffe verfügen nicht über einen Vernetzungsmechanismuss, welcher beim Spritzguss für die Ausbildung eines stoffschlüssigen Verbundes zum Untergrund genutzt werden kann (bei vernetzenden Elastomeren Vulkanisationsprozess).
• – Aufgrund der hohen Steifigkeit der Kunststoffe spielt der Aufbau von Spannungen aufgrund unterschiedlicher Wärmeausdehnung eine wesentlich größere Rolle.

In contrast to the material combination metal-elastomer, for which the use of adhesion promoters has long been state of the art, the material combination of metal-thermoplastic has in particular the following features:

• - Thermoplastics do not have a crosslinking mechanism, which can be used in the injection molding for the formation of a cohesive bond to the substrate (in crosslinking elastomers vulcanization process).
• - Due to the high rigidity of plastics, the buildup of stresses due to differential thermal expansion plays a much greater role.

State of the art

With the production of hybrid components made of metal and plastic it is possible to a considerable degree the advantages of both groups of substances in a favorable manner with each other to combine.

For the production of non-positive and form-fitting composites of such material combinations methods for mechanical joining have been developed, as for example in DE 19 934 545 C1 . DE 20 310 656 U1 . DE 10 133 292 A1 or DE 10 125 559 A1 are described.

For different applications, especially those where a (permanent) gas-tight or media-tight composite is required, very thin Applied plastic layers on a metal body be the components or strong mechanical and / or thermal Are subject to multiple burdens, are the currently common However, technologies of mechanical positive connection are not suitable.

One cohesive bonding is often not easy to achieve because many injection molding plastics have little or no adhesion show on metallic surfaces. This is partly because This is due to the fact that in the development of construction injection molding plastics As a rule, the liability behavior does not play a major role. On the other hand, there would be a strong liability tendency of the plastic on metals also for the demoldability of the molding rather disadvantageous.

In order to solve this problem, processes are increasingly being sought in which, with the use of special adhesion promoter systems, the required adherent and / or tight bond between metal and plastic is required can be produced.

Of the Use of adhesion promoters for the production of composites is a introduced and widespread technical principle. In the Lack- and adhesive technology or in the plastic technology in the production Bonding agents are widely used in composite films. Also at the production of injection-molded composites of metals and elastomers The application of adhesion promoters has long been common Practice.

For the production of injection molded hybrid components from metals and Thermoplastic plastics include the use of adhesion promoters not yet to the widely introduced state of the art.

In DE 10 303 368 A1 For the production of injection molded hybrid components, it is proposed to apply a layer to the insert. The task to be solved with this proposal consists mainly in the thus obtainable improved sealing of the cavity during the injection molding process and in compensation of tolerances of the insert. However, it is not specified what kind of systems are to be used for such a coating. The liability aspect is mentioned in the description, but without a technical teaching is given.

While of the injection molding process is applied to a substrate Primer exposed to special loads such. B. high Temperatures, increased pressure and pushing along the plastic melt on the coated substrate.

These Require requirements in connection with very short process times Special procedures that are significantly different from those more common Distinguish composite production when painting or gluing.

Difficulties also exist in mastering the problem of different thermal expansion properties and resulting stresses. In the DE 10 002 642 A1 described method to use materials with similar thermal material properties is not practical for many applications due to the consequent restrictions in the selection of materials.

The Use of layers of non-reactive polymers, similar Hot melt adhesives for adhesion promotion, since this is a melting / softening temperature significantly below the processing temperature of the injection-molded plastic have the limitations, that the layers flow away during the injection molding process on the one hand and on the other hand the resulting composite only one has low temperature resistance.

task

Of the The present invention is based on the object, a method to propose, which the production temperature-stable and media-dense Spritzgusshybridbauteile in a technically feasible way and under Avoiding the described disadvantages allowed.

Technical teaching

The Task is solved by that before the injection molding process a bonding agent applied to the substrate surface which is a multi-phase mixture of at least two network-forming Binder systems of different network formation temperatures represents (binder system I and binder system II).

basis and essence of the invention is that binder system II in the form of Solid particles in binder system I is used.

• a) ausreichend gute Haftfestigkeit der Bindemittelschicht auf dem Substrat
• b) ausreichende thermische Beständigkeit der Bindemittelschicht gegenüber den Beanspruchungen im Spritzgießprozess

The mode of action of the primer is described as follows:
Binder system I is taken as the liquid phase; it is characterized by the following properties:

• a) sufficiently good adhesion of the binder layer on the substrate
• b) sufficient thermal resistance of the binder layer with respect to the stresses in the injection molding process

In this liquid binder system I, the present in particulate form binder II is mixed, so that a suspension is formed. The bonding agent thus obtained is applied to the substrate after application a way dried (crosslinked) that binder system I is sufficiently solidified, but the reactivity of binder system II is largely retained. It is immaterial whether the drying of binder system I is only a physical process (evaporation of solvent or water) or a true chemical crosslinking. The decisive factor is that after drying / crosslinking there is a dry, solid layer on the substrate which still contains reactive particles of the binder system II.

When Binder system II, network-forming compositions are selected, their crosslinking temperature below the processing temperature of the injection molding plastic used. Through the networking process of binder system II wins the binder layer and thus the entire composite a high temperature resistance.

The Binder systems are selected so that at least a binder system a certain degree of elastic and / or has plastic properties to build up tension due to the different thermal expansion to reduce. The binder systems are selected so that at least a binder system forms a three-dimensional space network.

Both Binder systems can be used in addition to the actual Binders or their starting materials in the paint and / or adhesive technology usual Additives for influencing the processing or coating properties such as pigments, other solid fillers, catalysts, Retarder, surface-active substances of different Type, organically modified silicon compounds and others. Also need Both binder systems are chemically not uniform, but For example, mixtures of different film formers and crosslinkers included, crucial is the outlined functional principle.

It was found out by the use of a bonding agent Binder system I and binder system II in the described Form adhesive strength, media tightness and thermal resistance be significantly improved by metal-plastic injection molding can.

Quality Results are also achieved when as binder system II powder coating binder or even finished powder coatings are used.

embodiments

example 1

One Aluminum substrate (AlMg1) should be partially encapsulated with a plastic become. The surface of this aluminum insert is if necessary degreased and cleaned (eg UNICLEAN 151). After that will on the points to be connected to the plastic below described adhesion promoter mixture as evenly as possible painted. This coating will be at a maximum of 100 ° C dried until reaching the grip strength.

The prepared substrate is inserted into the injection mold and with the respective plastic at a processing temperature overmoulded by at least 180 ° C.

To a homogeneous mixture (binder I)
96 parts UNI-BOND WB 71017 EM9 and
4 parts of a 75% solution of HDI in ethyl acetate
5 parts of a PU powder coating (P 14 clearcoat Fa. Freilacke) was added.

The Powder is introduced so that a suspension is formed in the the powder is evenly dispersed.

Example 2

method as described in Example 1, wherein for the coating of the substrate, the adhesion promoter mixture described below is used.

To a homogeneous mixture (binder I)
96 parts UNI-BOND WB 71017 EM9 and
4 parts of a 75% solution of HDI in ethyl acetate
50 parts of a PU powder coating (P 14 clearcoat Fa. Freilacke) (binder II) was added.

The Powder is introduced so that a suspension is formed in the the powder is evenly dispersed. To achieve better processability can be diluted with water become.

Example 3

method as described in Example 1, wherein for the coating of the substrate, the adhesion promoter mixture described below is used.

To a homogeneous mixture (binder I)
80 parts TRIXENE BI 7963
20 pc-amine DA 250 become
20 parts of a PU powder coating (P 14 clearcoat Fa. Freilacke) (binder II) was added.

When using the method according to the invention, the bond strength of metal-plastic injection-molded composites can be increased to a considerable extent (Table 1) Tab. 1: Improvement of the adhesion of injection-molded composites of aluminum and plastic (PA 6 or ABS) when using the method according to the embodiments 1 to 3 bonding agent Adhesive strength (tensile shear strength) in% in combination with PA 6 SECTION without a bonding agent 9 8th Mixture of 96 parts of UNI-BOND WB 71017 EM9 and 4 parts of a 75% solution of HDI in ethyl acetate (corresponds to binder 1 according to Example 1 or 2) 100 100 example 1 180 138 Example 2 260 264 Example 3 215 168

The in the above description, the claims and the abstract disclosed features of the subject matter of this Documents can be individually, as well as in any combination among themselves for the realization of the invention in theirs various embodiments be essential.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19934545 C1 [0009]
• - DE 20310656 U1 [0009]
• - DE 10133292 A1 [0009]
• - DE 10125559 A1 [0009]
• - DE 10303368 A1 [0015]
• DE 10002642 A1 [0018]

Claims (6)

Process for the preparation of stable metal-plastic injection-molded composites, characterized in that a bonding agent is applied to the metallic substrate to be connected to the plastic, which contains two different binder systems. Crosslinkable solid particles of the binder system II are present in the adhesion promoter in the liquid binder system I in the adhesion promoter. After the adhesion promoter application binder system I is dried / crosslinked, the reactivity of binder system II is substantially retained. Method according to claim 1, characterized in that the melting and crosslinking temperature of binder system II lower than the processing temperature of the plastic melt. Method according to claim 1 or 2, characterized that the drying / crosslinking of the binder system I at temperatures takes place, which is below the crosslinking temperature of the binder system II lie. Method according to one of claims 1 to 3, characterized in that binder system I is a water-dilutable Binder system is. Method according to one of claims 1 to 3, characterized in that binder system I is a non-aqueous Binder system is. Method according to one of claims 1 to 3, characterized in that in the adhesion promoter additives and Processing aids are included.