DD205180A1 - METHOD FOR THE PRODUCTION OF ADHESIVE COMPOUNDS - Google Patents

Abstract

When using two-component reactive adhesives, a prior mixing of the individual components is not required according to the method. Separate application of the individual components and mixing of the components after joining in the glued joint is achieved according to the invention by adding fillers of a specific type, amount, grain size or grain size distribution to the resin and / or hardness components of the reaction substances which can be hardened by polyaddition, polycondensation or vulcanization , The effect of mechanical vibrations on the glued joint ensures the mixing of the individual components in the glued joint. Fillers with a cubic or spherical structure exert a favorable influence on the mixing effect. Application finds the invention solution in the flow and mass production of adhesive small to medium-sized components.

Description

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Process for the production of adhesive bonds

Field of application of the invention

The invention relates to a method for the production of adhesive bonds, preferably in the metal bonding technique, using two-component reaction adhesives, wherein the individual components are applied separately and the mixing is carried out after the joining of the individual parts in the adhesive joint.

Characteristic of the known technical solutions

It is known polymerizable reaction adhesives, z, B. acrylate-based, to process according to the so-called no-mix method, i. apply the individual components of these adhesives separately and merely add the components. However, since the hardener component in this adhesive group represents only one activator which initiates the polymerization reaction, it is not necessary to mix the components anyway (although in principle possible). All other reactive adhesives which are cured by polyaddition, polycondensation or vulcanization, and thus the majority of the mechanical adhesives, require precise metering and thorough mixing of the individual components before application.

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components. This leads, in particular with cold-curing reaction adhesives, which have only a short service life of about 30 to 60 minutes, to large adhesive losses and to a high cleaning effort of the mixing and application equipment. In the case of fast-curing reaction adhesives, whose service life is usually only a few minutes, there are even almost insurmountable technological difficulties in their application in flow and mass production.

It has already been proposed (DT-OS C 09j 5/04 2 131 256) to carry out a separate application of the resin and hardener component even with such adhesives, preferably on epoxy resin basis and mixing the individual components by merely joining the items by lightly moving or Heating the parts or by applying ultrasound to the bond line to achieve. Extensive in-house investigations have shown, however, that by all these measures only a completely insufficient mixing of the individual components takes place in the adhesive joint, which is expressed by low and strongly scattering strength values of the adhesive bonds.

Object of the invention

It is the object of the invention to develop a process for the production of adhesive bonds, in which the untey use of polyaddition, polycondensation or vulcanization curable reaction adhesives is carried out a separate application of the individual components and their mixing in the adhesive joint

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is taken and thus adhesive losses are avoided, minimizes the cleaning effort on mixing and application equipment, and the use of fast-curing reactive adhesives is made possible without complications.

The essence of the invention

The invention has for its object to develop a process for the production of adhesive bonds, preferably in the metal bonding technique, in which using two-component - reactive adhesives, a separate application of the individual components takes place and the mixing of the components is carried out after joining in the joint and with Safety high and uniform strength of the glued joints are guaranteed.

According to the invention the object is achieved in that the resin and / or hardener component of the polyaddition, polycondensation or vulcanization curable reaction adhesives fillers of a certain type, amount, particle size or grain size distribution are added, which in conjunction with the action of mechanical vibrations on the bondline, e.g. Ensuring the mixing of the individual components in the glued joint by means of ultrasound.

Incidentally, it is obvious that fillers of cubic or spherical structure (e.g., quartz flour, metal powders, glass beads) exert a more favorable influence on the mixing effect than those of leaf-leaved or fibrous structure (e.g., graphite, asbestos flour) and the amount of filler which is used

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Resin «and / or hardener component is added, it is chosen so that the known in the metal adhesive technology side effects such as increasing the strength of the adhesive bonds are used with (about 10 to 50 % filler addition to the adhesive). Since the grain size of the fillers determines the Klebfugendicke, which in turn has a decisive influence on the strength of the adhesive bond, it is also to choose in the previously known order of about 50 to 250 yum. Surprisingly, according to the invention, depending on the type of mechanical vibrations introduced in the bondline (longitudinal or transverse waves), the particle size distribution of the adhesive has a decisive influence on the mixing effect of the adhesive components in the bondline. In the introduction of longitudinal waves perpendicular to the bond, an optimum mixing effect of the individual components is only achieved if the filler added to the adhesive from a small 'share (about 5 to 25 %) of a Klebfugendicke determining grain fraction of about 150 to 250, / and a high proportion (about 75 to 95 %) of a grain fraction below about 150yura. In contrast, when transverse waves are induced parallel to the joint, the best mixing effect is achieved by a filler of uniform grain fraction d, which is in the range of about 50 to 250 μm.

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embodiment

The method will be explained in more detail below using an exemplary embodiment.

Using a filler-free two-component adhesive based on epoxy resin with a mixing ratio of the individual corona components of 1: 1 parts by mass, adhesive bonds according to TGL 14910/02 were prepared and tested for tensile shear strength at RT.

The achieved after the usual mixing of the individual components before 'applying to the test specimens is used as 100% basis.

In a separate application of the resin and hardener component per a test specimen half and mere assembly and cold curing under pressure, the strength is 0 %, ie mixing of the individual components in the joint by diffusion does not occur as expected * Also by a relative movement of the test specimen halves after joining By hand, a curing of the adhesive at 100 ⁰ C or an ultrasonic effect on the bond only an incomplete mixing effect of the individual components in the joint is achieved, which is expressed by strongly scattering strength values in the range of 10 to a maximum of 50 % .

Only by the inventive addition of3O % quartz powder of defined grain size to the resin and / or hardener component "and the initiation of mechanical vibrations in the bond joint complete mixing of the individual components in the joint is ensured and tensile shear strengths of 115 to 125% achieved, with a coefficient of variation below + 10 % ·

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When ultrasonic vibrations are introduced into the joint, only 2 to 10 seconds are required to mix the individual components in the joint, depending on the performance of the US plant

The best mixing effect is at the initiation of transverse waves parallel to the bond by a filler having a uniform grain fraction in the range of 50 to 250 / im, preferably 100 to 150 / Am, with introduction of longitudinal waves perpendicular to the bond, however, with a filler of at least 2 or more Grain fractions _K wherein the minor fraction reaches about 5 to 25 % of a grain fraction in the range of about 150 to 250 μm and the predominant fraction of about 75 to 95 % of a grain fraction below 150 μm, preferably about 50 to 100 μm.

Claims (3)

invention claims 1. A process for the preparation of adhesive bonds using polyaddition, polycondensation or vulcanization curable two-component adhesives, wherein the individual components are applied separately and the mixing is carried out after joining the parts in the joint by introducing mechanical vibrations, characterized in that the resin and / or hardener component fillers defined grain size or particle size distribution are added. 2. A process for the preparation of adhesive bonds according to item 1, characterized in that when introducing longitudinal waves vertically into the joint, the added filler consists of at least two grain fractions, wherein the smaller proportion of about 5 to 25 %, a grain fraction of about 150 to 250 / and the larger proportion of about 75 to 95 % has a particle fraction below 150 / Mn, preferably 50 to 100 / im. 3. A process for the preparation of adhesive bonds according to item 1, characterized in that when introducing transverse waves parallel to the bond joint, the added filler from a uniform grain fraction in the range of about 50 to 250 ^ um, preferably about 100 to 150 / im.