AT392608B - Process for producing an article from glass-fibre- reinforced plastic - Google Patents

Abstract

The invention relates to a process for producing an article from glass-fibre-reinforced plastic, in particular glass-fibre-reinforced, unsaturated polyester, from a prepreg. To avoid glass fibres 1 becoming exposed during weathering of the surface, it is provided according to the invention that at least on one side 3 of the prepreg there is applied a mat 4 which has an elongation at break of about 40% and which is chemically compatible with the plastic used, is wetted well with the said plastic and finally the article is cured. A polyester nonwoven with a strength of 40 g/cm2 is preferably provided as the mat. <IMAGE>

Description

AT 392 608 B

The invention relates to a method for producing an object from glass fiber reinforced plastic, in particular glass fiber reinforced unsaturated polyester from a prepreg.

In recent years, glass fiber reinforced plastics have been used increasingly for everyday items and also in technology. This is primarily due to their low weight, their low manufacturing costs, their easy formability and the possibility of being able to meet various mechanical, thermal and electrical requirements by selecting the plastic that is reinforced with glass fibers. Particularly unsaturated polyesters, epoxy resins and other thermosets are used as plastics, but also thermoplastics of the polyamide, polystyrene, polycarbonate and polyolefin type since the mid-1960s. '

The reinforcing elements, the glass fibers, can also take on non-fibrous form and can be used as game, fabric, 10 mats, nonwovens, short fibers, &quot; rovings &quot; (Strands of glass silk) and even as glass balls.

The production of the desired parts depends on the number of pieces to be produced, the complexity and size of the object and the plastic used. Various catalysts or accelerators can be added to the plastic.

In a special process, in which unsaturated polyester is used as the plastic, 15 a glass fiber mat or a layer of glass fibers is impregnated with the plastic and, if necessary, various additives, and wound on rolls (prepreg) for maturing. Depending on the thickness of the layer obtained, the type and amount of additives and the storage temperature, this ripening lasts from a few days to a few weeks. During this ripening, the unsaturated polyester is cross-linked to form a three-dimensional network.

When the desired degree of crosslinking is achieved, the mat is unwound from the roll, cut to the desired size and shape and brought to the desired final shape in a heated mold. The ripening process is completed by the pressure, in part also the temperature and the deformation, and the part removed from the mold is ready for use.

When parts made in this way are used outdoors, the outer side of the object is inevitably slightly weathered. This weathering is so slight that the mechanical, thermal and electrical properties of the object are not affected. However, it is sufficient to expose the outermost layer of the glass fibers and make them accessible to humans and animals. This is undesirable in view of the unpleasant mechanical properties of the glass fibers, causing redness and eczema when penetrating the skin, and also causing discomfort or even illness when entering the respiratory tract or esophagus, and is a problem when such materials are used outdoors So far, this problem has not been solved.

A composite material is known from DD-PS 202 265, in particular for chemical apparatus engineering. A supporting layer made of glass fiber reinforced plastic is coated with a suitable liner which is selected in accordance with the respective chemical environment. In many cases there is only a low level of adhesion between the two layers. For this reason, it is proposed to build the liner 35 on a specially treated polyester fiber fleece that comes into contact with the glass fiber-reinforced layer and adheres well to it. There are no weathering problems with this application.

DE-OS 25 34 188 solves the problem of creating molded parts with smooth surfaces made of GRP. For this purpose, foils are laminated onto the surface of the GRP. According to DE-OS, a foil is used that is 3 - 40 vol.% Filled with fillers, optionally again glass fibers. Even such a surface does not withstand weathering; on the contrary, there is a risk of the film becoming detached.

The aim of the invention is to provide a solution to the problems stated above and to obtain all the other desired properties of the material.

According to the invention, it is provided that a mat is applied to at least one side of the prepreg, the elongation at break of which is approximately 40% and which is chemically compatible with the plastic used, 45 which it wets well, and finally the object is cured. A polyester fleece with a thickness of 40 g / cm ^ has proven particularly useful for use with unsaturated polyester.

It has been shown that during the manufacture of the web, which is then temporarily stored for ripening, the unsaturated polyester plastic preferably penetrates into the polyester fleece and forms a layer of polyester on the later outside of the article, which layer is substantially thicker than the layer which is customary 50 lies above the uppermost glass fiber layer. It has also been shown that the production can be carried out with the usual application devices for the unsaturated polyester, but it is of course possible to provide an additional polyester application between the reinforcement made of glass fibers and the polyester fleece.

All the qualities of the blank normally produced can also be made with the polyester fleece used according to the invention, since the only difference in the preferred embodiment 55 is the increased mass of the blank by about 40 g / m 2, this increase in mass being practical in the areas of application in question is imperceptible.

The invention is illustrated by the following examples and the drawing.

1 shows a schematic cross section through a conventional press part,

2 shows a schematic cross section through an analog pressed part which is produced according to the invention with a fleece 60 on the outside of the object,

Fig. 3 shows a section of the outside of a conventional pressed part made of glass fiber reinforced -2-

AT 392 608 B

Plastic that has been exposed to the weather for some time and

FIG. 4 shows a press part produced according to the invention which was exposed to the weather under the same conditions as the press part according to FIG. 3.

As can be seen from Fig. 1, in conventional pressed parts made of glass fiber reinforced plastic, the glass fibers (1) are tangled and relatively evenly distributed over the entire volume of the pressed part. Also on and in the outside (3) of the pressed part, which is exposed to the weather, there are glass fibers Depending on the strength and history of the formation of the glass fibers, these can be rather straight and / or, as shown in FIG. 1, curved and curved. As mentioned at the beginning, reinforcements can also be used which have no or no such pronounced fiber shape.

Fig. 3 shows the outside (3) of a pressed part according to Fig. 1, whereby even with slight weathering bundles (2) of glass fibers, which run at least approximately parallel to the surface of the pressed part, are exposed and are released from the pressed part even at low mechanical loads to solve. This makes the press part an unpleasant and potentially dangerous object, especially for children and animals.

As shown in Fig. 2, the pressed part produced according to the invention has at least on its outside (3) a fleece (4) which presses the glass fibers (1) into the inside of the pressed part. The density of this fleece shown is not necessarily the actual density correlatable, the thickness of the fleece was drawn greatly enlarged to show its mode of action.

The difference in the weathering test as can be seen in FIGS. 3 and 4 is astonishing. Since a photographic illustration was not possible due to the surface structure, the surfaces were shown in drawings. The black border on the upper and lower edges of the samples was clamped in the automatic weathering machine and therefore has the original smooth surface.

In the case of the conventional pressed part, entire tufts (2) of glass fibers, in this case running in a straight line, are exposed and can be detached from the part with just a light touch. Only individual fibers (1) are visible in the part produced according to the invention, and these, too, can hardly be removed from the composite, since most of these fibers are only exposed over part of their length.

It is of course possible to further improve the surface properties by selecting the fleece. For example, a second mat can be arranged on the same side of the part, or a fleece can also be provided on the inside (3 ') in order not to have to pay attention to its orientation when processing the mat.

As an example of a composition of the glass fiber-reinforced pressed part, the recipe is given according to which the pressed parts were manufactured, the weathering behavior of which is shown in FIGS. 3 and 4: 30.8 g of unsaturated polyester resin (VIAPAL VUP 4619 from Vianova Kunstharz AG); 0.25 g 1.4 benzoquinone (Merck 2408) 5% in styrene, filtered; 0.6 g tert. Butyl perbenzoate (Trigonox C from Akzo Chemie); 38.5 g of a solution or dispersion of thermoplastics and fillers in styrene (Additol VXT 5923 from Vianova Kunstharz AG); 3.6 g of a pigment concentrate from organ and / or inorganic. Pigments and a monomeric, unsaturated polyester resin (color paste 7222); 1.4 g of zinc stearate (Zinkum N 37 SL from Bärlocher); 25 g of aliminium hydroxide (Martinal ON 310 from Martinswerk GmbH); 25 g aluminum hydroxide (Martinal OL 104 from Martinswerk GmbH); 0.6 g magnesium oxide (Maglite DE from CALGON CORP.); 1 piece of glass mat according to DIN 1259, part 1 (VETROTEX, E-glass from Gevetex Textilglas-GmbH).

In addition, in the case of the pressed part produced according to the invention: 9 1 piece of polyester fleece with a density of 40 g / m.

The thickness of the fleece in g / m ^ is common in plastics technology. The thickness preferred according to the invention ensures that the glass fibers (1) are essentially completely displaced from the area of the surface (3) which is subject to weathering. -3-

Claims (2)

5 AT 392 608 B PATENT CLAIMS - 1. Process for the manufacture of an object made of glass fiber reinforced plastic, in particular glass fiber reinforced unsaturated polyester from a prepreg, characterized in that a mat is applied to at least one soap of the prepreg, the elongation at break of which is approximately 40% and which is chemically compatible with the plastic used, wetted well by it and finally the object is cured. 15 2. The method according to claim 1, characterized in that when using unsaturated polyester as reinforced plastic, a polyester fleece with a thickness of 40 g / cm ^ is provided as a mat. 20 Including 2 sheets of drawings $ -4-