DE2746544A1 - Rendering silicone rubber mouldings heat-weldable - to each other or to other plastics by partly embedding polyolefin particles into them before completing vulcanisation - Google Patents

Abstract

Weldable silicone rubber moulding is flock-coated with polyolefin powder and/or fibres, at least on 1 side, partly or entirely. The flocking is partly anchord in the rubber. Used e.g. in tubes, panels, sheets, etc. suitable for mfr. of models, elastic casting moulds, in the electrical industry. Silicone rubber mouldings being normally difficulty weldable to other silicone rubber articles or to disimilar, but weldable, mouldings, are improved in this respect by the polyolefin flocking.

Description

Weldable silicone rubber molded body

The present invention relates to a weldable silicone rubber molded body, e.g. in the form of a tube, a plate or a film.

Silicone rubbers (polysiloxanes) are called hot or cold vulcanizing Products e.g. as molded and injection-molded parts, for elastic casting molds, in model making, as potting compounds, among other areas of application in technology, especially in electrical engineering, used many times.

The silicone rubber types are characterized above all by their high permanent temperature resistance, their good low-temperature elasticity, the good dielectric properties, the Weather and aging resistance as well as the water-repellent behavior.

A significant disadvantage of the moldings made from silicone rubber However, it can be seen in the fact that the molded body is not with itself or with others weldable parts can be connected by hot welding.

The task was molded bodies, e.g. in the form of pipes, Sheets or foils, to create, which are welded to themselves or to other substances can be.

The above-mentioned object is achieved by a weldable one Silicone rubber molded body, the distinguishing feature of which is that it at least on one side partially or fully with polyolefins in shape is flocked by powders and / or fibers and / or fibrids, the flocking is partially anchored in the rubber.

Polyolefins with up to 6 carbon atoms can be used, however, polyethylene is preferred.

The powders preferably have grain sizes in the range from 0.5 to 500 um, while the fibers or fibrids preferably have a length of 0.05 to 15 mm.

Even if, according to the invention, any shaped body can be welded by flocking can be made, pipes, hoses, sheets or flat films are preferred manufactured.

The moldings can be flocked over the whole area if it is not fixed at which points welding is to be carried out, or the shaped bodies are to be welded over the entire surface.

Partial flocking is sufficient if the welds are set in advance. For example, only the edges of sheets or flat foils can be used flocked on one or both sides, e.g. if an overlap weld is planned is.

It is also possible to use only the abutment surfaces e.g. of pipes that are also may have a flange to flock, thereby connecting different tubes to each other be welded can.

But not just the welding of the silicone rubbers to itself is solved according to the invention. So it is possible to use composite materials with the silicone rubbers to manufacture.

For example, the shaped bodies can be welded to others in the form of foils Materials are partially or fully covered by certain properties to achieve.

For example, it is possible to produce the molded bodies, e.g. in the form of flat films or hoses, to be connected with deep-drawable foils, creating a deep-drawable Material is created.

There are other options, e.g. a fully flocked one To connect flat foil with e.g. thin metal foils made of e.g. aluminum, if the Aluminum foil also has a weldable layer.

As can be easily seen, the invention results weldable molded body made of silicone rubber numerous possible combinations, whereby the properties of different materials are used together can.

With flocking on both sides, there are further possible combinations of materials, e.g. a thermoplastic plastic on one side and a metal foil can be welded on the other side.

The partial welding also only allows certain areas to connect with possibly different materials and / or parts.

There is a method for producing the shaped bodies according to the invention in that it is preformed, for example by casting, but not yet fully vulcanized Silicone rubber mass as soon as possible before they vulcanize the polyolefins applies and then fully vulcanized.

The connection with other parts is done with the help of known ones Welding techniques, e.g. by thermal impulse welding.

The invention will now be described using a few selected examples, without, however, there should be any restriction to this.

Example 1 A two-component silicone rubber (Wacker SilGel 601) was molded into a plate-shaped body. By heating to 1000C it was vulcanization initiated.

After 45 seconds, the entire surface of the plate was coated with polyethylene powder (Particle size 80% <5 μm, Liposorb 100) dusted and the powder lightly pressed on. After further heating up to 60 seconds, the vulcanization was complete.

The excess polyethylene powder was blown with air removed.

The 0.5 mm thick film produced in this way was sealed with a sealable 100 µm thick polyvinyl chloride film, heat-sealed. This composite was easy to deep-draw. It could be used to make cups, bowls and other objects.

Example 2 A film according to Example 1 was produced. The foil could be welded well to the same foil.

Example 3 A film according to Example 1 was produced. These Foil was made by heat impulse welding with a polyethylene-coated aluminum foil welded from 20 pm.

The bond adhesion was very good.

Example 4 The silicone rubber according to Example 1 became two tubular bodies with a diameter of 50 cm and a wall thickness of 1.5 cm. Shortly before the vulcanization ended after 3 min with heating to 1000C the cut edges of the pipes on one side with a polyethylene powder coating with a Grain size up to a maximum of 300 µm flocked. After a short pressure and complete vulcanization the excess powder coating was removed by blowing on it. The flocked ends the two pipes could be hot-welded.

The adhesion was good.

Example 5 Example 1 was repeated, except that instead of the polyethylene powder Polyethylene fibers with an average fiber length between 1.0 and 2.35 mm were used.

The welding with the polyvinyl chloride film was very good, too the deep-drawability of the composite.

Example 6 Example 1 was repeated, except that a two-component silicone rubber was used, which under the name Wacker silicone rubber RTV-ME 622 im Is commercially available.

The same good results as in Example 1 were achieved. Of the The difference was that the composites achieved here in relation to the silicone rubber exhibited higher elasticity and tear resistance.

Example 7 Example 4 was repeated, except that the two-component silicone rubber of Example 6 was used.

The results were the same as in Example 4 and in terms of elasticity and tear resistance to those of Example 6.

Example 8 The silicone rubber of Example 6 in the form of a sheet was made shortly before the vulcanization in strips with a polyethylene fiber with a average length between 1.5 and 3.5 mm flocked, with one Mask served.

The flocked strips were coated with a polyethylene Thermoformable polyester film, heat-sealed.

The composite was deep-drawable at the coated areas, while the places in between were flat.

The invention is further illustrated by the following figures explained where these are idealized and not because of the better graphic representation are carried out to scale.

A restriction to the embodiments shown is also intended not pass.

FIG. 1 shows a side view in section through a silicone rubber film 1. In the entire surface, the polyolefin powder 2 are embedded, the give the film the ability to weld.

FIG. 2 shows in a side view in section the film according to FIG. 1, which can be connected over the entire surface with a sealable film 3.

FIG. 3 shows a side view in section through a silicone rubber film 1. In the entire surface, the polyolefin fiber 2 are embedded, which give the film the ability to weld. The metal foil 3 carries a weldable Layer 4 that can be welded to the polyolefin fiber particles.

FIG. 4 shows a sectional side view of a polyolefin powder particle on both sides 2a, 2b flocked silicone rubber film.

FIG. 5 shows a sectional side view of three partially with polyolefin powder particles flocked silicone rubber parts 1 and 5. On the flocked Place the parts can be welded together.

FIG. 6 shows a sectional side view of two flanged ones Silicone rubber pipe pieces 6 and 7, which are partially flocked with polyolefin powder particles are. Welding can be carried out at the flocked areas.

FIG. 7 shows a sectional side view of one of the silicone rubber film 1 and the hood-shaped silicone rubber body 8 existing packaging for the Item G. The welding took place at the previously flocked points 2 of the Parts 1 and 8.

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Claims (5)

Claims 1. Weldable silicone rubber molded body, thereby characterized in that it is partially or fully covered with polyolefins at least on one side is flocked in the form of powders and / or fibers and / or fibrids, the flocking is partially anchored in the rubber. 2. Shaped body according to claim 1, characterized in that the flocking made of polyethylene. 3. Shaped body according to one of claims 1 or 2, characterized in that that the flock consists of powder particles with a size of 0.5 to 500 µm. 4. Shaped body according to one of claims 1 to 3, characterized in that that it is designed as a tube, hose, plate or flat film. 5. Shaped body according to one of claims 1 to 4, characterized in that that it is at least partially or over the whole area with another weldable part connected is. i Process for the production of a shaped body according to the claims 1 to 5, characterized in that the, e.g. by casting, preformed, but not yet fully vulcanized silicone rubber mass as soon as possible before it Fully vulcanize the polyolefins and then fully vulcanize them.