NO834256L - PROCEDURE FOR MANUFACTURING COMPOSITE PLATES - Google Patents

Abstract

1. Method of manufacturing by moulding in a single pass, a moulded composite panel comprising a base formed from discontinuous glass or rock fibres, impregnated with a polymerized binder and a visible covering sheet, characterised in that an initial component is prepared by impregnation by soaking with a non-polymerized binder so as to obtain an initial component with a binder ratio of approximately 10 to 30% by weight of the total dry extract, at least one layer of fibres bonded with a polymerized binder, obtained by spraying on the fibres, a solution of the non-polymerized binder during the formation of the layer of fibres, followed by the polymerization of the binder, whereby the ratio of the polymerized binder is approximately 2.5% by weight of the layer of bonded fibres, that the initial component is placed on the visible covering sheet and that all the components are pressed accompanied by heating so as to obtain the composite panel by polymerization of the binder and bonding of the components between themselves.

Description

The present invention relates to shaped composite plates

which comprises a carrier made of at least one layer of fibers impregnated with a polymerized resin and at least one cover foil and in particular a method and a device for producing such plates.

Shaped composite boards of this type are e.g. interior linings in the passenger compartment of motor vehicles where the carrier made of at least one layer of fibers impregnated with a polymerized resin plays the role of an acoustic and thermal insulating material,

while the cover foil, which is usually referred to as giving an appearance and which is made of fabric and which faces the interior of the compartment, gives it an aesthetic appearance.

Plates produced in this way can also be used as decoration in a room where they provide thermal insulation and an acoustic treatment by being hung on the walls, where they can form removable or movable elements in these rooms.

Upholstery, sound screens, screen boards, blinds, partitions, etc. can also be made from shaped composite elements or coated with shaped composite elements.

It is known to produce composite panels by a method where the various operations take place step by step.

A blank is then first produced, i.e. a "felt" of impregnated fibers with a non-polymerized binder, usually a thermosetting resin. For this purpose, an aqueous preparation of the binder is sprayed onto the fibers during the production of the felt. The carrier of the composite board is then shaped by shaping of one or more blanks laid on top of each other by simultaneously using heat and pressure. During this shaping operation, the heat will polymerize the binder and produce cross-linking or polycondensation in the case of a thermosetting resin. The cover film is then applied to the semi-rigid carrier, after which this is sprayed on and /or a suitable adhesive on the cover foil.

This manufacture with subsequent operations has

several disadvantages. It requires more work positions and is therefore expensive in terms of manpower. The manufacturing line takes up a lot of space and to this is added a significant storage space. This type of production makes it possible with significant production times. The total yield of such a line is small.

In French patent no. 1 289 745 it is proposed to produce shaped composite sheets in a single step, where the binder for the fiber layer is hardened, while the thermoplastic cover foil is given a waffle pattern and at the same time attached to the fiber layer. .The thermoplastic cover foil softens and forms during heating to a temperature that is necessary for polycondensation or cross-linking of the binder, which is in the order of 200°C.

Such a procedure in a single step cannot be carried out

in the case where the appearance-giving cover foil is a substance or, in general, a material which is sensitive to the high temperature necessary for cross-linking of the binder and/or to the various physio-chemical attacks of the binder. In addition to its small resistance to heat, i.e. to temperatures of the order of 200°C during the time periods necessary for the polycondensation, i.e. approx. 3 minutes, the cover foil during forming will be in contact with the raw material, where the binder is not polymerized and will be exposed to physical or chemical attack by it. Furthermore, the method described in the French patent mentioned above will require the use of a covering foil which is tight and which forms a barrier against penetration of the binder. Spraying of the binder in the traditional methods for producing the fiber felt will therefore be able to produce local collections of binders on

due to turbulence in the transport gas and the production of areas with too much binder. These collections can

give rise to a penetration of the binder through a permeable covering foil which may be made of fabric and which may cause stains to appear on the appearance surface of the tyre.

The invention avoids these disadvantages and proposes a new method of forming in a single step for the production of a composite plate comprising a carrier of discontinuous fibers impregnated with a binder and in particular a thermosetting resin and an appearance-giving cover foil in particular of material which is relatively sensitive to temperature and/or non-polymerized binder. . According to . the invention ..a raw material is produced by wetting through with a non-polymerized binder to impregnate at least one discontinuous fiber layer which has been previously glued together,

such as an insulating board produced in a manner known per se, where discontinuous fibers are connected with a binder which has already polymerized but which is present in a small amount, on the provided raw material an appearance-giving covering film made of special fabric is placed and the whole is pressed and heats moderately during reduced time to

achieve a polymerization of the binder and a bonding between the two elements in the composite plate.

The moistening to produce a blank according to the invention allows an even distribution of the binder among the fibers,

you avoid accumulation in certain areas that you would get with an impregnation by atomizing the binder. This homogeneous distribution makes it possible to reduce the duration of the pressing and the minimal duration of the polymerization. You not only avoid the breakdown of the cover foil by heat,

but also stains caused by the accumulation of non-polymerized binder. Furthermore, the wetting method which is known in and of itself, e.g. from US patent no. 2,698,260 make it possible to adjust very precisely the content of binder in the raw material and in the final product, since this method

makes it possible to influence the various parameters such as the concentration of the solution that distributes, the duration of the impregnation, etc.

The method according to the invention can take place completely continuously. One can thus carry out the wetting of the fiber which has been glued together in advance directly after its manufacture, and then use the raw material directly for the forming operation, where both of these operations take place without intermediate storage. This process will usually require several forming stations to collect all blanks that are formed.

In order to make the process more industrial, flexible, the invention can also be carried out while carrying out . an intermediate storage of pre-glued felt.

Since the binder contained in the felt is fully polymerized, there will be no problems with aging of the felt. Furthermore, this felt can be pressed together without inconvenience during storage.

One can also imagine an intermediate storage of raw materials

which are impregnated.

The wetting operation is done most easily when it is carried out on

a continuous band of felt that is glued in advance. Furthermore, the felt can be stored in the form of a roll which can either consist of

of pre-glued felt or impregnated blanks or both.

Binders used for the wetting consist of a resin that can be chosen from among thermosetting resins such as phenoplasts or aminoplasts. Phenoplast resins are preferably used, which have good temperature and humidity properties and which are also cheap.

The binder used for wetting preferably contains a phenoplast resin selected from the group of phenoplast resins

which have a pH between 1.5 and 3 and those which have a pH between 8.5

and 12, the latter being preferred because of the acidic nature of the former. Such resins have interesting polymerization properties and in particular a relatively low curing temperature of the order of 150-180°C and a relatively short curing duration of the order of 1%-2 minutes for the felt thicknesses and binder contents used within the invention. These properties further reduce the risk of degradation during the forming of the fragile cover film, especially of fabric. Furthermore, the use of such resins will reduce energy requirements.

These phenoplast resins are e.g. a phenol-formaldehyde-..harpdks of. the xesol type. modified with urea and has. e.g.

a ratio between formaldehyde and phenol of between 2 and 5, catalyzed in a basic environment with alkali or alkaline earth oxides, the resin is neutralized at pH 7 by the addition of dilute sulfuric acid. For resins with a pH between 1.5 and 3, these are adjusted by adding water and an acid to the base resin,

while resin having a pH between 8.5 and 12 is adjusted by adding water and a base to this resin.

The wetting of the fiber felt by binder can be carried out by

to pass the felt through a binder bath. The wetting preferably takes place, due to the simplicity of the design, by distributing the binder on the felt which is displaced.

The moistening is carried out in such a way that a raw material is obtained

with a binder content of the order of 10-30% of the total dry weight. For this purpose, you can use the binder preparation which has a viscosity close to that of water.

The felt from which the raw material is made can be felt made of fiberglass, stone wool, slag and other discontinuous fibers that can withstand the forming temperature. The content of polymerized binder before wetting amounts to approx. 2.5% by weight of the felt. According to one embodiment of the invention, a thermoplastic binder in the form of a film, preferably a net, is placed between the raw material and the appearance-giving cover foil. This thermoplastic adhesive improves the connection between the raw material and the appearance-giving cover film and the thermoplastic net has a lower price than the film.

The thermoplastic adhesive can be placed at the moment where

the different elements of the composite board are brought together.

You can also assemble the raw material and the adhesive in advance especially to facilitate the handling of the raw material.

The thermoplastic adhesive is selected from among those that have a melting temperature that is compatible with the operating conditions, i.e. that is lower than the forming temperature. One uses e.g. polyethylene.

The appearance-giving cover foil can e.g. be a velor fabric, a polyamide or a polyester.

According to the preferred embodiment of the invention, the wetting with binder of the pre-glued felt will be followed by drying by compression and/or by suction and then drying in dry air, e.g. between 80 and 100°C which ..moves at a speed of approx..10 m/sec..over the felt to produce a blank that contains little residual water, i.e. in the order of 5% by weight or less in relation to to the total weight of this. The heat supplied during the forming is then used mainly to polymerize the binder in the raw material and to glue the cover foil to it.

The aforementioned drying should of course not produce

a premature polymerization of the binder in the raw material.

According to another aspect of the invention, the shaping is carried out

in a single step of a plate which further has an outer cover layer, i.e. which faces the vehicle and which has the role of making it easier to mount the shaped plate, making it stiffer and avoiding direct contact with the fibres. This cover layer

can be produced as a synthetic film, from a metal film or composite film.

The temperature used for shaping according to the invention is usually below 180°C on the side that has the appearance-giving cover foil. On the opposite side, the temperature can be higher, in the order of 250°C, without risking degradation of the appearance-giving cover foil, while at the same time obtaining rapid polycondensation in the resin.

In a preferred embodiment of the invention, hot is blown

air over the blank during forming to accelerate the polymerization of the binder and further reduce the duration of

..the formation operation.

The invention also relates to .en. fabrication line for

the shaped composite panels. This line comprises a device for glue impregnation which makes it possible to produce a blank according to the invention and a forming device with a press equipped with two heated plates to carry out the forming. An embodiment of these devices is described below with reference to the attached drawings.

The invention also relates to a blank which is impregnated

with adhesive and which is thus an intermediate product and which can be used to carry out the forming operation according to the invention.

Fig. 1 shows an impregnation device for felt to

produce a raw material according to the invention.

Fig. 2 shows a detail of the device in fig. 1.

Fig. 3 shows a device for forming to produce

the final composite plate.

The impregnation device shown in fig. 1 and 2 comprise a conveyor belt with wire mesh 1, which is pulled by rollers to transfer the felt during the impregnation operation, where a container 2 for the felt to be impregnated 3 and which already contains approx. 2.5% by weight polymerized binder. Placed above the front part of the conveyor belt is a container 4 which is continuously fed with non-polymerized binder by means of supply lines 5. This container is placed transversely in relation to the felt to be impregnated, it extends in a width that is somewhat greater than the felt, so that you get a homogeneous wetting of this along the entire width. The container comprises a horizontal reservoir 6 where the front wall 7, which has a smaller height than the rear wall 8, is extended with an inclined iron 9 through which the binder 10 flows outwards and forms a band.

. The.lower end of the iron which is inclined and placed

at a distance h approx. 50 mm from the felt to be impregnated. It is located under the front part of the conveyor belt

a vessel 11 to capture excess binder that drips through and these are connected to suction devices 12 such as a ventilator that ensures drying of the impregnated felt and a recycling system 13 for the binder. In front of the distributor and above the conveyor belt there is a vertical blowing box 14 which carries hot air from a line 15 to the impregnated felt. This warm air that passes through the felt 3 to dry it is sucked up by means of suction devices such as a ventilator 16 connected to a suction box 17 placed under the blower box 14 and then recycled.

A roller 18 is placed at the end of the conveyor belt 1

to pick up a roll of supplied raw material 19. At the outlet of the moistening device, the raw material has a water content of the order of 5% by weight or less. The part of the felt that is subjected to direct liquid removal has a length of approx. 0.80 m, while the part where drying is carried out using hot air has approx. double length. These lengths will of course depend on the entrainment speed of the felt, which e.g. can be of the order of 2 m/min.

Forming devices shown in fig. 3 comprises a press

20 with a frame 21, and two heated plates 22 and 23.

The upper plate 22 is mounted on hydraulic jacks

24 and can approach in the direction of arrow F or move away from the lower fixed plate 23.

At the entrance to the forming device there is a first container 25 for the blank 19 and a second container 26 for an outer cover layer 27. It comprises a pair of rollers 28 and 29 to bring together the blank 19 with the outer cover layer

27. A third container 30 distributes a mesh of polyethylene

31 which is placed on the pre-assembled blank in front of an assembly table 32 where the assembled blank is placed on a frame 33 which is applied with an appearance-giving cover foil 3.4 distributed from the container 35 pl.asser.t . under the mon.ter-j.ngs table 32.

A cutting device C for the raw material, appearance-giving cover foil and the polyethylene mesh is placed after the assembly table.

Even if the shaped product does not have an outer cover layer or the conditions are such that the adhesion between the appearance-giving cover foil is such that you do not need to use polyethylene mesh, you can use all the parts of the device described above.

An embodiment that is not shown of a mold device is equipped with blowing devices where at least one of the plates

in the press is perforated with openings so that you can blow through all or parts of the composite board.

Other advantages and characteristics of the invention will become apparent

of the following examples.

The first example represents a starting point for comparison with the following examples in order for the advantage of the invention to emerge.

EXAMPLE 1

A felt of discontinuous glass fibers that has a weight

of 1350 g/m<2> is impregnated during the production of a binder which is a phenoplast resin with pH 6-7 by spraying a solution of this binder. The dry matter in the solution is adjusted to 25% by dilution with water. The phenoplast resin is modified with urea and produced with a molecular ratio between formaldehyde and phenol of 3 in the presence of only hydroxide as a catalyst; it is neutralized to pH 6-7

by adding dilute sulfuric acid, and the phenoplast resin is modified with urea so that the content is approx. 50%. The raw material that is provided is placed on an appearance-giving cover foil made of fabric. The whole thing is placed in a press. The pressing is carried out to obtain a product of an average size

of approx. 6 mm. The duration of the pressing is approx. 3 minutes, the press plate on the same side as the blank is at 240°C, while the one on the same side as the appearance-giving cover foil is at 150°C. The shaped product has correct mechanical properties, especially a good stiffness, but has spots on the side with the appearance foil of fabric. These stains are due to the build-up of binder, which is due to the atomization of the product as stated above.

EXAMPLE 2

A felt made of discontinuous glass fibers that has been glued together in advance has a content of polycondensed binder of approx. 2.5% by weight and a weight of 1350 g/m<2> is impregnated with a binder of phenoplast resin with pH 6-7 by wetting and using a device as described above with reference to fig. 1 and 2, by distributing on the felt a solution of binder described in example 1 but diluted by the addition of water to obtain a dry matter content of approx. 20% by weight. The displacement speed of the felt is approx. 2 m/min. The impregnated raw material is freed of excess liquid, and is then dried by suction and passage in hot air at approx. 20°C with a displacement speed of

about. 10 m/sec. until it has a water content of approx. 5% by weight. The raw material is then fed to the forming device described

of fabric. It is all placed in the press. The pressing is carried out under the same conditions as in example 1. The pressed product has an average thickness of approx. 6 mm and the correct mechanical properties. You can't see any stains on it

the appearance-giving cover foil.

EXAMPLE 3

You proceed as in example 2, except that you reduce the pressing duration to 2 minutes. You get a molded product with a correct appearance, but which is relatively soft due to incomplete polymerization of the resin.

EXAMPLE 4

Mon. goes .f rem under the ..same conditions as in example

3, except that a binder of phenoplast resin with a pH of 9.2 is used. This binder is prepared by diluting and adding sodium hydroxide to the resin from the previous examples to adjust the pH to 9.2.

You get a shaped product with the correct appearance and stiffness. The polycondensation is faster than in example 3, and a duration of 2 minutes for the pressing is sufficient to obtain

a complete or quasi-complete polymerization.

EXAMPLE 5

You proceed as in example 3, except that you use

a binder of a phenoplast resin with pH 2. This

•the resin is produced by diluting a phenol-formaldehyde resin from example 2, where sulfuric acid is added to

pH 2. You get a shaped product with the correct appearance and stiffness. In this case too, the polymerization of the binder is faster than in example 3.

EXAMPLE 6

You proceed under the same conditions as in example 4, except that you place a polyethylene film between the raw material and the appearance-giving foil. You get a shaped product with the correct appearance and stiffness. Furthermore, the bond between the appearance-giving foil and the substrate will be particularly strong.

EXAMPLE 7

You proceed as in example 6, except that you place a mesh of polyethylene between the raw material and the appearance-giving foil instead of a polyethylene film. The shaped product has good mechanical properties and a good appearance, and the connection between the appearance-giving foil and the substrate is strong.

EXAMPLE 8

One proceeds as in example 7, except that in addition . places.on the blank.an outer covering layer. The shaped product has good mechanical properties and a good appearance and is otherwise easy to handle.

Claims (19)

1. Method of production by forming in a single step to produce a composite board consisting of a support of discontinuous fibers impregnated with a polymerized binder and an appearance-giving foil, characterized in that a blank is produced from at least one layer of pre-glued fibers that are impregnated with a binding agent by moistening and by placing the raw material on the appearance-giving cover foil, after which the whole is pressed and heated to produce the composite board. 2. Method according to claims 1 and 2, characterized in that the moistening is carried out by distributing binder on the layer of pre-glued fibers. 3. Method according to claims 1 and 2, characterized in that this binder is a thermosetting resin. 4. Method according to claim 3, characterized in that the thermosetting resin is a phenoplast resin. . 5. Method according to any one of claims 1-4, characterized in that the phenoplast resin is a resol modified with urea and the molecular ratio between formaldehyde and phenol is preferably between 2 and 5. 6. Method according to any one of claims 4 and 5, characterized in that the phenoplast resin is selected from among phenoplast resins with a pH between 1.5 and 3 and those with a pH of between 8.5 and 12. 7. Method according to claim 6, characterized in that the phenoplast resin has a pH in the order of 9.2. 8. Method according to any one of claims 1-7, characterized in that a thermoplastic adhesive is placed between the raw material and the cover foil. 9. Method according to claim 8, characterized in that the adhesive is in the form of a net. 10. Method according to claims 8 and 9, characterized in that the thermoplastic adhesive is polyethylene. 11. Method according to any one of claims 1-10, characterized in that one -wetting the .fibres .with the binder ..drying...the coating off. impregnated fibers until it has a water content of the order of 5% by weight or less. 12. Method according to claims 1-11, characterized in that a cover layer is placed on the side of the blank which is opposite to the side where the appearance-giving foil is placed. 13. Method according to any one of claims 1-12, characterized in that the two sides of the composite plate are heated to different temperatures during forming. 14. Method according to any one of claims 1-13, characterized in that hot air is blown through all or parts of the raw material during shaping. 15. Method according to any one of claims 1-14, characterized in that the fibers from which the raw material is produced are glass fibers. 16. Device for carrying out a method according to any one of claims 1-15, characterized in that it comprises an impregnation line for wetting a fiber layer by means of a binder to produce a blank and a press for forming in a single step of the supplied raw material (19) and an appearance-giving cover foil (32) which is fragile at high temperature and which is preferably made of fabric. 17. Device according to claim 16, characterized in that the impregnation line comprises a conveyor belt (1) for the felt to be impregnated (3), a distributor (4) placed above the conveyor belt and which extends to a width that at least corresponds to the width of the felt to be impregnated and where the binder is distributed from, a collection . dude. (-1.1) with a recycling system (.13) for the binder, and devices for drying in front of the distributor (14, .17). 18. Composite plates, characterized in that they are produced by the method according to any one of claims 1-15. 19. Method for the production of a blank, characterized in that it is to be used for the production of a composite plate according to claim 18. '.2 0- Raw material, characterized in that it has been prepared to carry out the method according to claim 19.