Pressed , disc shaped material , use of the material and method for the production thereof

TECHNICAL FIELD:

The present invention relates to a pressed sheetformed material which consists of plastics and glass fibres and which can be used as an equipment material in vehicles , buildings, e t c, especially as dashboard and equipment details in cars .

PRIOR ART:

An almost countless number of kinds of materials which are based on glass fibre reinforced plastics are known. Such materials can be used for many different purposes and their properties vary very strongly dependent on what kind of plastics, which are contained in the materials, and the way in which they have been produced. These materials are usually cheap and they have for most applications sufficiently good properties.

A known application for such materials are as equipment details in cars. In these the perhaps most dominant use of the plastic materials are as dashboards and as protection or shields at different places.

Dashboards for cars consist today mostly of a polyurethane plastics which is a foam material without mechanical strength with an outer layer of a plastic sheet. To give the dashboard sufficient mechanical rigidity the plastic

materials are mounted on an inner plate or the like. Apertures for different instruments in the dashboard are usually reinforced with plate details. The outer sheet should be mixed with plasticizers or for instance other plastic materials such as polyvinyl chloride to get the right properties. It is also usual that the outer layer is painted, partly to give the surface the right pleasant appearance, partly to prevent evaporation of additions to the plastics, which additions bring about so called fogging which means covering on the windscreens and the like.

TECHNICAL PROBLEM:

Production of for instance a dashboard according to the above is a complicated and expensive process. It is required that one first by punching out produces the plate part and treats this one so that the plastic material thereafter will adhere to the plate in a safe way and thereafter mould together plate, polyurethane and sheet in moulds. The residing time for such product in the mould after the application of the plastic materials.on the plate part is very long, about 3-5 minutes, which means that one must have a great number of moulds to be able to bring about a continuous production. One has to calculate with 15-20 moulds plus punching tools for this purpose dependent on number of details per year.

Due to the fact that several plastic materials and plastic materials together with metal plates are parts of the product environment problems will arise both at the production and when the product later shall be destroyed by disintegration or is thrown away on some refuse tip.

It has therefore long been desired to be able to produce materials which can replace the above mentioned materials as equipment details such as dashboards and the like. These

materials should be environmental friendly and they should also be such that they allow a quicker and cheaper production of the details and have a lower weight.

THE SOLUTION:

By the present invention one has solved the problems at the known materials and their use and brought about a pressed sheetformed material consisting of a carrying layer of a glass mat reinforced thermopolymer (GMT) having an adhering thinner layer of the same or some other polymer.

It is according to the invention advantageous that the polymer in the GMT-material consists of polypropene having a material temperature of 190-200°C and the polymer in the thinner layer of polypropene with a melting point of 145- 150°C.

The glass mat reinforced polymer GMT should have a content of glass fibres of about 30-40 weight-%.

The invention includes further use of the pressed material as a construction material for details or equipments in for example cars and airplanes, especially as dashboards.

The invention comprises further a method for the production of pressed sheetshaped materials in accordance with the invention which is characterized in that one produces a pre-shaped thermoplastic film in a negative mould part whereupon one or more layers of flowable glass mat reinforced thermopolymers (GMT) at the flowing temperature is introduced into the mould on the pre-formed thermoplastic film and that the material thereafter is joined and formed by pressure and heat.

The thermoplastics in the film and in the GMT-material should be the same as those mentioned above.

According to the invention the positive mould part, that means the male part, should be cooler than the negative mould part, that is the female part, and have a temperature of 40-50°C, preferably 42 + 2°C and the negative mould part a temperature of 60-70°C, preferably 62 + 2°C.

The pre-formed film should according to the invention have a thickness of about 1,5-2,0 millimetres and should be embossed on that side that shall adhere to the GMT- material.

The joining and the forming of the material occurs by means of a pressure of about 150-200 bar (15-20 N/mm ² ) and heat.

To obtain a successful result of the method the negative mould part should be embossed so that gases released can escape and the surface of the finished product get a pleasant appearance.

FIGURE DESCRIPTION:

The invention will in the following be described more in detail in connection with the attached figure, which in a vertical section shows the moulds pulled apart and with introduced materials intended to be pressed.

PREFERRED EMBODIMENT:

In the figure a negative mould part 1 and a positive mould part 2 are shown. In the mould part 1 one has first introduced a pre-shaped and pre-pressed film 3 which in the present case consists of polypropene having a melt point of 145-150°C. The thickness of this film is about 1,5-2,0

millimetres. The reason for this is primarily that the negative mould part 1 is embossed so that air and gases are allowed to escape and that the film shall be able to receive this embossment form. If the film is too thick it will not get this embossment pattern, if it is too thin it will not be sufficiently strong. In the mould on the pre- shaped film 3 a number of layers of glass mat reinforced thermopolymer (GMT) adapted to full filling of details have been put in. This material consists in the present case of polypropene having a melting point of 190-200°C and the content of glass fibres in the polypropene is about 40 weight-%. Even other contents of glass fibres for example 27 or 30% can be thinkable as such are commonly available in the market.

To press the product the positive mould part 2 is pressed against the negative mould part 1 at a pressure of 120-200 bar (15-20 N/mm ² ) . This pressure should be maintained during only about 20 seconds which means that introducing of materials, pressing and removing of the finished product requires 40-50 seconds or at most one minute. Compared to earlier known methods as mentioned above, this means a time saving of 3-4 minutes for each pressing.

As appears from the figure the GMT-material has been introduced into the mould in three layers having different size. It is important that the GMT-material is introduced in a proper way and in the present case this material has been adapted so that it shall flow upwards in the mould and fill this accurately. Therefore the three layers have been made in the way which is shown. During pressing the GMT- material flows out as mentioned and maintains also during the flowing the even distribution of glass fibres so that the product gets a homogeneous composition all through. The pre-formed film 3 does however not flow out as it abuts against a surface well under the melt point and maintains

its pre-pressed shape. This means also that the pre-pressed film 3 can be given folded edges in advance as the flowable GMT-material will fill up the cavities which are formed through this folding. Any folding of the film afterwards will therefore not be necessary and the joining of the film and the GMT-material occurs consequently completely in one single operation.

The negative mould part has as said above a temperature of 60-70°C whereas the positive mould part can be somewhat cooler and have a temperature of 40-50°C. Herethrough one gains the advantage that by cooling the film against the positive mould part the product will not attach to this which facilitates the removal of the product from the mould parts.

ADVANTAGES:

Through the present invention one gets the advantages that the production of press shaped products according to the above for example dashboards for cars, will be much cheaper and quicker compared to what is usual today. One obtains even better economy by the method and the product also by refraining from a carrying plate and besides that gets a lighter product. Any reinforcement of through going apertures in the product by means of a plate is neither necessary as the product has an inner strength which is sufficient.

The product and the method according to the present invention is also environmentally adapted. One gets a simpler production by which one avoids chemical treatment of the plates for improved adherence and at which environmentally dangerous waste besides that can be avoided. The only effluent gases which arise are small amounts of liberated propene at the pressing operation.

The finished product is in itself also environmentally friendly in that it comprises only one type of plastics, preferably polypropene. This facilitates highly the final destruction of the material which besides the plastics only contains glass fibres, which material as is well known is environmentally friendly.

The material according to the invention does not have the same tendency to so called "fogging" as earlier known materials. One can however if one so wishes paint the film before it is pre-pressed and introduced into the mould. This can also be an advantage also therethrough that it then can be given a more scratch-resistant surface.

The good attachment between the GMT-material and the thinner film, which partly is brought about therethrough that the bordering surface of the film against the GMT- material has been embossed in advance, makes also the strength at crashes larger. This strong attachment has also the consequence that splintering of the product in question by crashes is prevented. This is for security reasons much important, especially at cars.

The material according to the present invention is especially suitable as material in dashboards and equipment details for cars, airplanes and the like. It can however also be used for different purposes for example as glove lockers in cars, shields against cold air streams in the drivers compartment in lorries, as parts of the engine bonnet in lorries but also as equipment parts of different kinds for example in chairs and diverse furniture.

The invention is not limited to the embodiment example shown but can be varied in different ways within the scope of the claims.