WO2003013829A1

WO2003013829A1 - Unit and procedure for the impregnation of organic and/or inorganic fibres with synthetic resin

Info

Publication number: WO2003013829A1
Application number: PCT/EP2002/008531
Authority: WO
Inventors: Alfonso Branca; James Dean Francomb; Edward Louis D'hooghe
Original assignee: Top Glass S.P.A.
Priority date: 2001-08-03
Filing date: 2002-07-31
Publication date: 2003-02-20
Also published as: ITMI20011711A0; ITMI20011711A1

Abstract

The unit and method for the impregnation of organic and/or inorganic fibres with synthetic resin comprises a first closed chamber for containing a predetermined quantity of synthetic resin, comprising means for feeding the synthetic resin and the fibres into the first chamber, means for impregnating the fibres with the resin, means for calibrating the impregnated fibres and means for heat treating the impregnated and calibrated fibres.

Description

UNIT AND PROCEDURE FOR THE IMPREGNATION OF ORGANIC AND/OR

INORGANIC FIBRES WITH SYNTHETIC RESIN

DESCRIPTION

The present finding refers to a unit and a procedure for the impregnation of organic and/or inorganic fibres with synthetic resin.

As is known, the impregnation of organic and/or inorganic fibres with synthetic resin constitutes one of the fundamental steps in pultrusion processes.

Indeed, as is known, pultrusion is a process for the continuous production of profiles with a constant section of composite material (glass fibres impregnated with resin) .

The main steps of the pultrusion process are the preparation and the housing of the glass fibres, the impregnation of the fibres in the synthetic resin, the preforming and the drawing of the composite material .

In pultrusion procedures, for example, depending upon requirements, polymeric (resin) matrices which at room temperature are in liquid form (e.g. thermosetting resins) or in solid form (e.g. thermoplastic resins) can be used.

In particular, in the case of pultrusion with thermosetting resins which are in liquid state at room temperature (e.g. liquid phenolic resins) , the glass fibre is made to pass through an open bath, for example inside an open basin which contains the resin, so as to increase the soakability of the glass fibre.

Inside the basin there can be a soaking roller which deposits the resin on the glass fibres, or else there can be a guide roller with the function of forking the glass fibre, under which it is made to runs, immersing said fibre inside the resin bath.

In a different solution a closed bath can also be used with pressurised pumping of the resin which can escape, for example, through the holes or from the overflow of the closed basin.

In a different pultrusion procedure the glass fibre, without wetting it, is made to enter the inside of a mould in which there is an injection chamber presenting one or more injectors which allow the glass fibre also to be impregnated with more colours and with different resins.

From what has been stated above it is useful to note that pultrusion procedures which use resins which are liquids at room temperature by their very nature or resins which are liquid because they are diluted in solvents, still allowing a good impregnation of the glass fibre, thanks to the high viscosity of the resin which can easily pass between fibres, have the drawback that the evaporation of the solvents makes the working environment unhealthy with all the drawbacks which derive from this problem.

Moreover, liquid resins have chemical and physical characteristics which rapidly change in time with the consequent problems of handling and storage.

Indeed, due to the presence in the liquid phenolic resin of solvents which, amongst other things, give off formaldehyde and phenol to the atmosphere, in this case a refrigeration treatment is often necessary for it to be stored.

In the case of pultrusion, realised through the use of synthetic resins which are solid at room temperature, such as thermoplastic resins, the resin is turned into a fluid through heating.

Subsequently, in order to impregnate the glass fibre with resin in the best way, a forced impregnation must be carried out since the thermoplastic resin often does not have the soakability of the thermosetting resin.

For this reason the forcing takes place through the engagement of heated rollers to achieve a predetermined pressure which allows, on the one hand to fork and open the glass fibre and, on the other hand, allows the fibre to be completely soaked by the resin during the passage between the rollers .

In this second case there are substantial drawbacks due to a substantial waste of electric energy since one has to heat the resin and the rollers of the unit and keep them at a predetermined temperature.

Since the rollers work in the open air, the heat produced dissipates in the air.

Moreover, in these units there is a substantial waste of resin since, as it falls during the passage of the glass fibres in the rollers, it is lost and its recovery is not possible due to the elevated costs which such an operation would require . Moreover, it can be observed that thermoplastic resin, with which the glass fibre passing through many rollers is impregnated, loses its viscosity in the passage from one roller to the next due to the lower temperature outside of the roller.

For this reason numerous rollers are used which, however, on the negative side, can be the cause of damage to the fibre which is forced to follow a path with sharper corners.

Due to the above, units of this type, since they have many passages of the same fibre in a high number of rollers to work together with a predetermined number of fibres or many fibre heads in succession, so as to obtain an excellent impregnation, have a substantial longitudinal and/or transversal extension.

In both of the aforementioned cases, once the glass fibre is impregnated, it is made to pass through calibrators suitable for giving the composite material (defined by a glass fibre impregnated with resin) the predetermined size and the shape.

For both of the procedures described above, the calibrators must be heated and carry out, during their operation, a rubbing action on the glass fibre which, consequently, determines the carrying away of the resin from it, being lost, as already stated, in the case of thermoplastic resin, or polluting the environment in the case of thermosetting resin.

The task proposed of the present finding is to eliminate the drawbacks of the prior art reported above . In this task, an important purpose of the finding is to realise a unit and a procedure for the impregnation of organic and/or inorganic fibres with synthetic resin which allows pultrusion procedures using either liquid or solid, thermosetting or thermoplastic resins to be carried out. Yet another purpose of the finding is to realise a unit and a procedure which avoid, in the case of liquid resins, the evaporation of the solvents into the working environment. A further purpose of the finding is to realise a unit and a procedure wherein it is possible to use thermosetting resins in solid state at room temperature so as to avoid alterations in their chemical-physical characteristics in time, avoiding, moreover, the use of refrigeration systems as is the case for liquid phenolic resins and also allowing characteristics of greater mechanical resistance, ease of handling and transportation to be achieved.

A further purpose of the finding is to realise a unit and a procedure which avoid a waste of electrical energy in the case of use of thermoplastic resins for keeping them at the predetermined viscosity, allowing, moreover, a total recovery of the thermoplastic resin without any additional cost for such an operation.

Another purpose of the finding is to realise a unit and a procedure which allows a constant viscosity to be maintained from the beginning to the end of the impregnation treatment of the glass fibres with the resin, in addition to a saving in energy and a substantial decrease in the loss of resin, which prevents the formation of a film (due to an T between resin and room temperature) which affects the homogeneity of the viscosity of the resin.

The last but not least purpose of the finding is to realise a unit and a procedure which allow a pultrusion process to be realised in a totally cost-effective and healthy way, with the realisation of a product which is excellent from the point of view of mechanical resistance.

This as well as other purposes are achieved by a unit for the impregnation of organic and/or inorganic fibres with synthetic resin characterised in that it comprises a first closed chamber, for containing a predetermined quantity of said synthetic resin, comprising means for feeding said synthetic resin and said fibres in said first chamber, means for impregnating said fibres with said resin, means for calibrating said impregnated fibres and means for the thermal treatment of said impregnated and calibrated fibres. Also forming an object of the present invention is a procedure for the impregnation of organic and/or inorganic fibres with synthetic resin characterised in that it consists of introducing said resin and said fibres into a first closed chamber, of impregnating said fibres with said resin inside said chamber, subjecting them to a predetermined pressure suitable for allowing them to be completely soaked by said resin, of filling said first chamber with said resin up to a predetermined level, of keeping said level of said resin inside said first chamber constant, of calibrating in said chamber said fibres impregnated with said resin and of subjecting said impregnated and calibrated fibres to a heat treatment .

Further characteristics and advantages of the invention will become clearer from the description of a preferred but not exclusive embodiment of the unit and of the procedure according to the finding, illustrated for indicating and not limiting purposes in the attached drawing wherein:

- figure 1 is a schematic side view from above of the unit according to the finding

With particular reference to figure 1, the unit according to the finding, wholly indicated with the reference number 1, comprises a creel 30 where the glass fibres 3 are housed and guided, which are subsequently made to pass, for example through a preforming station, where they are accurately arranged for the subsequent steps and in particular the impregnation step.

The unit comprises a first closed chamber generically indicated with 2, in which is contained a predetermined quantity of synthetic resin with which the glass fibre 3, which is introduced in the chamber 2, needs to be impregnated.

On one side or on both sides of the glass fibre 3 introduction area there are the inlets 4 for the pressurised synthetic resin.

Preferably, on the opposite side to the inlets 4 there are the outlets for the fibre impregnated with resin. The inlets for the fibre are arranged in alternation with the inlets for the resin.

Moreover, the inlets and the outlets for the fibre are sized in such a way as to allow the fibre impregnated with resin to leave, but not to return backwards and pass through the inlets .

Inside the chamber are arranged the means for impregnating the glass fibre 3 with the synthetic resin, indicated with 5.

At the end of the impregnation means 5 there are the calibration means 6 which are associated with the chamber 2 and which are suitable for providing the composite material with its predetermined size and shape.

The calibration means can be outside or inside the closed chamber 2.

Finally, following or integrated with the calibration means, a second chamber 7 is foreseen for carrying out the heat treatment of the impregnated and calibrated fibres which come out of the first chamber 2.

In particular, the means of impregnation are arranged inside the first chamber which is closed on all sides (except for the inlets and the outlets for the fibres and the resin and the fibres impregnated with resin) and are arranged between the means for feeding the synthetic resin 4 and the glass fibre 3 inside the chamber and the calibration means 6.

Advantageously, the impregnation means comprise at least one calibrating member and preferably two calibrating members 11 and 12 which exhibit the surface 14 which comes into contact with the glass fibres which follows a curved path.

The impregnating member can be defined by a cylindrical or semi -cylindrical element or even by a continuous duct which extends inside the chamber following a sinusoidal path with one or more curves.

More precisely, the contact surfaces 14 exhibit a predetermined radius of curvature suitable for causing a suitable pressure and forking of the fibre to allow the full soaking of it by the synthetic resin and, consequently, a valid impregnation of the glass fibre.

Advantageously, moreover, the synthetic resin which is introduced into the closed chamber 2 fills up said chamber in such a way that its level is always kept above the impregnating members 11 and 12.

The level of the synthetic resin inside the first closed chamber 2 is, moreover, kept at optimal values thanks to the level detection means 15 defined, for example, by a pressure probe which is operationally connected to the feeding means

4, so as to manage the entry of the resin according to the quantity of resin which has been taken out by the impregnated glass fibre which has left the calibration means 6.

The unit foresees, moreover, first means for heating the first chamber 2 and/or the impregnating members 11 and 12.

The first heating means 20 allow a heating which is homogenous inside the first closed chamber 2, so as to guarantee a constant viscosity from the beginning to the end of the impregnation treatment of the glass fibre with the synthetic resin eliminating the possible formation of a surface film on the resin which negatively affects the homogeneity of the viscosity of the resin itself.

Moreover, there is no waste of energy for keeping the resin at optimal levels of viscosity and, most importantly, the loss of resin is completely eliminated, with the resin thus always being kept inside the chamber 2 and only being taken out from the chamber in the amount which was necessary for the impregnation of the glass fibre.

Thanks to this solution, the first closed chamber 2 is completely full of resin and therefore completely free of air and always remains at a constant temperature, so as to guarantee the constant and homogenous viscosity of the resin.

Thanks to this solution, the points of contact between the impregnating members and the glass fibre heads can be reduced and allow suitable angles to be achieved for guaranteeing a suitable pressure on the glass fibre, so as to make it fully soaked by the resin.

Indeed, a single impregnating member can be advantageously placed inside the closed chamber 2 thanks to the fact that other points of contact can be defined by the closed chamber

2 itself for each glass fibre head and thus it is possible to line up many impregnating members, for example according to a stacked arrangement, in order to be able to treat many glass fibre heads without having an excessive transversal encumbrance, with it no longer being necessary to treat each glass fibre head in succession with many impregnating members .

The calibration means 6 are, moreover, equipped with second heating means 31 which advantageously have autonomous operation with respect to the first heating means. From what has been said one can see two important advantages : the fact that the first chamber 2 is completely filled with resin allows the impregnation of the glass fibres to be optimised so as also to be able to carry out such an operation with only one or two impregnating members and the entry of the impregnated glass fibre directly into the calibration means, i.e. into the pultrusion mould, allows the excess resin to be left inside the bath so as to use up a minimum amount of such resin and of energy required by the procedure .

In this way it is possible to realise a thermoplastic synthetic resin by providing heat to the first closed chamber, or else it is also possible to use a synthetic resin of the thermosetting type and preferably a phenolic resin which is a solid at room temperature with all the aforementioned advantages which this solution brings. Preferably, the synthetic resin is a depolymerizable and repolymerizable thermoplastic resin and, in particular, the resin is a thermoplastic resin derived from polymacrocyclic oligomers (dicarboxylate alkenes) , macrocyclic polyester oligomers or other polymerising agents with a ring opening which form linear thermoplastics. Also forming the object of the present invention is a procedure for the impregnation of organic and/or inorganic fibres with synthetic resin which consists of introducing both the synthetic resin and the glass fibres into a first closed chamber.

In a subsequent step the glass fibre is impregnated with the resin inside the chamber subjecting said fibre to a pressure and a predetermined forking so as to allow its total soaking by the synthetic resin so as to optimise the impregnation thereof.

In the first closed chamber the introduction of the synthetic resin allows it to be filled up to a predetermined level and, thus, to keep the level of resin inside the first chamber advantageously constant thanks to the fact that only the quantity of resin which has actually been taken away during the impregnation of the glass fibre shall be introduced into the chamber, since all of the remaining resin is recovered and kept in a state of optimum fluidity and homogenous so as to be able to be used continuously.

Once the fibres are impregnated, they are calibrated, i.e. the composite material made up of the glass fibre impregnated with resin is brought to the size and shape of profile that one wishes to obtain.

Finally, the impregnated and calibrated fibres are made to undergo a heat treatment which takes place inside and/or outside the first chamber.

In particular,γ the heat treatment consists of providing a predetermined quantity of cold 22, in the case where thermoplastic resins are used during the pultrusion procedure, or else a predetermined quantity of heat 21, in the case where thermosetting resins are used during the pultrusion procedure.

In particular, in the procedure which is the object of the present finding, the resin which is used is a synthetic resin which is solid at room temperature and is brought into liquid state inside the first closed chamber, then kept at an appropriate temperature so as to guarantee a constant viscosity.

Advantageously, the resin is a depolymerizable and repolymerizable synthetic resin which is solid at room temperature and which is kept in liquid state inside the chamber which keeps it at an appropriate temperature and viscosity.

Suitably, the resin is a thermoplastic resin derived from polymacrocyclic (alkene dicarboxylate) , macrocyclic polyester oligomers or other polymerizing agents with ring opening which form linear thermoplastics which are solid at room temperature and which are kept in liquid state inside said chamber which keeps them at an appropriate temperature and viscosity.

More precisely, the solid resin is a solid phenolic resin which is mixed with a cross-linking agent made up of hexamin and in particular of hexamin capsules.

It has, in practice, been noted how the unit and the procedure according to the finding are particularly advantageous to allow, in the case where liquid resin is used:

- the evaporation of solvents such as formaldehyde and phenol (in the case of phenolic resins) into the air to be avoided so as to allow a healthy working environment;

In the case where solid resins, such as thermoplastic resins or solid phenolic resins, are used, there is:

- a further saving of electrical energy;

- an almost total recovery of the unused resin without having to carry out any special recovery operations;

- a maintenance of the homogeneity of the viscosity which is constant from the beginning to the end of the treatment, i.e. until the end of calibration;

- a highly contained number of impregnating members, since, amongst other things, they work whilst immersed in the synthetic resin which is used; a containment of the transversal encumbrance, since at least one or two impregnating members are sufficient to treat a glass fibre head;

- an achievement of suitable angles between the impregnating members so as to guarantee a suitable pressure on the glass fibre, thanks to the fact that fewer impregnating members are used. Since the calibration means or the pultrusion mould is situated directly at the end of or inside the closed chamber the recovery of the resin ejected by the calibrator is also permitted.

Last but not least, an extremely important advantage which is gained is that also with air present (air bubbles or air pockets present inside the closed chamber) due to the chamber being closed and heated, the resin in contact with the bubbles or pockets of air does not undergo any physical/chemical alteration (for example the formation of a surface film as would happen in the case of an open bath) . Moreover, with respect to open systems, and this is where lies one of the most important advantages of the finding, in which there is always one part of the resin in contact with the heating part (high temperature Tl) and one part of the resin in contact with the air present in the room (low temperature T2 , with T1>T2) , a film forms which affects the homogeneity of the viscosity of the resin.

In this situation, moreover, the closed chamber 2 can be combined with a member suitable for creating a decrease in pressure inside of it suitable for easing the removal of the bubbles or pockets of air from the resin.

Thanks to the use of solid phenolic resin it is possible to avoid its handling and storage problems, since it stays at the optimum state without the need of refrigeration. The finding thus conceived is susceptible to numerous modifications and variants, all falling within the inventive concept; moreover, all of the details can be replaced by technically equivalent elements.

In its practical embodiment, the materials used, as well as the sizes, can be whatever according to the requirements and the state of the art .

Claims

1. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin, characterised in that it comprises a first closed chamber for containing a predetermined quantity of said synthetic resin, comprising means for feeding said synthetic resin and said fibres inside said first chamber, means for impregnating said fibres with said resin, means for calibrating said impregnated fibres and means for the heat treatment of said impregnated and calibrated fibres.

2. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to claim 1, characterised in that it comprises first means for heating said first chamber and/or said impregnation means.

3. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said closed and heated chamber keeps the homogeneity of the viscosity of said resin constant, avoiding the formation of a film on it during the impregnation of said fibres.

4. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said first closed and heated chamber keeps the chemical-physical characteristics of said resin unaltered also when bubbles or pockets of air are present .

5. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that it comprises means for detecting the level of said resin inside said first chamber.

6. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said impregnation means are housed inside said first closed chamber and are arranged between said feeding means and said calibration means .

7. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said impregnation means comprise at least one impregnating member exhibiting at least one contact surface with said fibres with a curvilinear course .

8. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said impregnating member is a duct with sinusoidal extension equipped with one or more curves .

9. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said contact surfaces have a radius of curvature suitable for imparting an appropriate pressure on said fibres for them to be completely soaked by said resin.

10. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that it comprises second heating means associated with said calibration means which has an operation which is independent from said first heating means .

11. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said means for detecting the level comprises a pressure probe operationally connected to said feeding means to keep said resin at an optimum level inside said first chamber.

12. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that the level of said resin inside said first chamber is set above the level of said impregnation means.

13. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said chamber exhibits the inlets for said resin arranged alternately with the inlets for said fibre.

14. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said chamber comprises a member for realising a decrease in pressure inside of it.

15. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said synthetic resin is a thermoplastic resin.

16. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said synthetic resin is a depolymerizable and repolymerizable thermoplastic resin.

17. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said resin is a thermoplastic resin derived from (alkene dicarboxylate) polymacrocyclic oligomers, macrocyclic polyester oligomers or other polymerizing agents with ring opening which form linear thermoplastics .

18. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said synthetic resin is a thermosetting resin and preferably a phenolic resin which is a solid at room temperature and said fibres preferably consist of glass fibres .

19. Procedure for the impregnation of organic and/or inorganic fibres with synthetic resin characterised in that it consists of introducing said resin and said fibres in a first closed chamber, of impregnating said fibres with said resin inside said chamber, subjecting them to a predetermined pressure suitable for allowing them to be totally soaked by said resin, of filling said first chamber with resin up to a predetermined level, of keeping said level of said resin inside said first chamber constant, of calibrating, in said chamber, said fibres impregnated with said resin and of subjecting said impregnated and calibrated fibres to heat treatment .

20. Procedure for the impregnation of organic and/or inorganic fibres with synthetic resin according to claim 17, characterised in that the optimum level of said resin in said first chamber is obtained by feeding said chamber with a quantity of resin substantially equal to the quantity of resin used to impregnate said fibres.

21. Procedure for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said resin is a synthetic resin which is solid at room temperature and which is kept in liquid state inside said chamber, maintaining it at an appropriate temperature and with a constant viscosity.

22. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said resin is a synthetic resin which is a depolymerizable and repolymerizable resin which is solid at room temperature and which is kept in liquid state inside said chamber which keeps it at an appropriate temperature and viscosity.

23. Unit for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said resin is a thermoplastic resin derived from (alkene dicarboxylate) polymacrocyclic oligomers, macrocyclic polyester oligomers or other polymerizing agents with ring opening which form linear thermoplastics which are solid at room temperature and which are kept in liquid state inside said chamber which keeps them at an appropriate temperature and viscosity.

24. Procedure for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said resin is a solid phenolic resin and that said fibres preferably consist of glass fibres.

25. Procedure for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said solid phenolic resin is mixed with a cross-linking agent made up of hexamin.

26. Procedure for the impregnation of organic and/or inorganic fibres according to one or more of the previous claims, characterised in that said hexamin is a hexamin capsule .

27. Procedure for the impregnation of organic and/or inorganic fibres with synthetic resin according to one or more of the previous claims, characterised in that said resin which is solid at room temperature is kept with the same fluidity during the entire impregnation treatment until the start of the calibration treatment in order to keep the chemical-physical characteristics of homogeneity of the viscosity of the resin unaltered even when bubbles or pockets of air and like are present.