TECHNICAL FIELD

The present invention is intended to disclose a procedure for the flocking of profiles as well as the flocked profile produced thereby. The term "flock" relates in different technical sectors to a surface of velvety characteristics . In particular, the present invention relates to the sector of profiles made, for example, from rubber .

BACKGROUND ART

Said type of flocked rubber profiles , such as for example EPDM (non-conjugated ethylene-propylene-diene terpolymer) are used, for example, in the automobile sector, to make outer seals on sliding car windows , thanks to the excellent properties of resistance to atmospheric conditions of EPDM rubber . Said profiles have a velvety surface, known as flocked, which has the function of reducing the friction of the window with the profile .

The method known until now for the flocking of surfaces in rubber profiles in a line consists of passing the profile during the extrusion process through a chamber or area with controlled temperature and humidity where an adhesive is applied to the surface of the profile to be flocked and the flock is then deposited by ' electrostatic fields . After leaving the flocking chamber or area, the profile is introduced into a hot channel or oven so that it polymerises the adhesive used by heat .

This method has several drawbacks , including the following : - The profiles typically require a very narrow flocked surface in comparison with the width of the profile, meaning that the installation

has a low yield.

- It requires an installation of great length for flocking in line (in the order of 50 or 60 metres) . - Both the rate of flocking and the extrusion rate of the profile are limited by the cross- linking time of the adhesive in the hot channel .

- The quality of the flocking produced is not totally satisfactory, as the hairs comprising the flock do not remain perpendicular to the flocked surface , but form a variable angle with the surface as a function of the curve thereof and its spatial position.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided procedure for the flocking of rubber profiles , characterized in that it comprises the steps of providing a flocked tape which has a desired width of flock and whose base , intended to come into contact with the surface of the profile, comprises an olefinic compound chemically compatible with a polymer present in the rubber profile ; heating of the rubber profile and the flocked tape ; and forming a contact bond between the rubber profile and the flocked tape .

According to a second aspect of the invention, there is provided flocked rubber profile produced according to a procedure in accordance with any of claims 1 to 8 , characterized in that it comprises a rubber profile tightly bonded to a flocked tape which has a base that comprises an olefinic element chemically compatible with a polymer present in the rubber profile .

According to a third aspect of the invention, there is provided a flocked sealing profile comprising flocked tape which has a desired width of flock and a base, intended to come into contact with the surface of the profile , characterised in that the base comprises an olefinic compound chemically compatible with a polymer present in the rubber profile, and in that the rubber profile and the flocked tape are contact bonded together by applying heat .

Obj ects of the embodiment of the present invention to be described in detail below are to achieve a flocking system for rubber profiles which requires an installation occupying the least possible space , has a better yield and whereby a flopk of bette.r quality is produced than using the procedures currently known for this type of profiles .

To do this , the embodiment provides for the use of a flocked tape which has previously been cut to the required width and it is brought into contact with the rubber profile at a suitable temperature, producing a tight bond between the rubber and the flocked tape .

Rubbers are heat-stable materials , which means that to achieve the bond by heating and contact provided by the embodiment , the flocked tape, which may be of the type commercially available, should include in its base, intended to make contact with the profile surface, an olefinic element compatible with one of the polymers which form part of the rubber formulation .

The tests and experiments performed by the inventors show that the presence of said olefinic element on the base of the tape, surprisingly, enables a tight , long-lasting heat bond with the rubber profile, despite the known fact that rubbers are heat-stable materials , i . e . they do not flow as the temperature increases .

The heating temperature of the tape should preferably be close to the melting point of the selected olefinic component . ^'

Preferably, the olefinic component will be short-chain . More preferably, this will be ethylene .

Depending on the composition and structure of the rubber, the olefinic component present in the base of the tape , may be added as an additive thereto .

The flocked tape , being a normal product on the market , and previously cut to the desired width, may come from a reel during the flocking process .

The present invention also provides a flocked profile obtained using the flocking procedure . This rubber profile may have tightly bonded to its surface a flocked tape of the type commercially available , formed by a base and a flock, in which there is no intermediate adhesive between both components .

The embodiment has numerous advantages over those previously known, amongst which can be cited : - ^: Reduced investment in the flocking line . The space necessary to apply the flocked tape is approximately two metres , much less than with the known procedure . Constant quality of the flock throughout the profile .

Increase in the flocking speed, as it is not limited by the cross-linking time . As a consequence , the rate of extrusion of the profile can be increased. - Increase in yield, as it eliminates the loss of flock which escapes the adhesive . ^• Reduction in the so-called quality costs . In the

case of defective flock, it is not necessary to throw away the profile, but just dispose of the tape .

For better understanding of the invention, an embodiment will now be described by way of example only with reference to the accompanying drawings in which

Figure 1 is a diagram which represents a process of manufacturing a flocked rubber profile which uses the flocking procedure according to the present invention .

Figure 2 is a perspective view of a flocked tape , in rolled up position, and already cut to be applied to a profile, with a detail of its flocked side .

Figure 3 is another perspective view of the tape of figure 2 in which a detail of the side intended to make contact with the surface of the rubber profile is shown. Figure 4 is a cross-section view of a profile according to the present invention in which the bonding process between the profile and the flocked tape has been represented diagrammatically.

Figure 5 is a front elevation view of a flocked rubber profile produced ^• according to the present invention .

Figure 6 is a cross-section view according to the plane VI-VI of figure 5.

Figure 7 is a rear elevation view of the profile of figure 5.

Figure 8 is a detail of the flocked area of the section of figure 6 , which shows in additional detail the bond between the rubber profile and the flocked profile .

Figure 1 shows the manufacturing process of a flocked EPDM profile 1 , in which the procedure is used according to the

present invention . As can be observed in the drawing, the manufacturing of a rubber profile comprises , typically, the step of extrusion of the profile 2 , which precedes a vulcanization phase by microwaves or UHF vulcanization, indicated in the drawing by the reference numeral 3 , and a subsequent vulcanization phase by adding heat in a gas channel , indicated in the drawing by the reference numeral 4. At the exit of this last vulcanization phase , the profile 1 passes to the flocking area 5.

Characteristically for the present embodiment , within the flocking area 5 both the profile 1 and the flocked tape 6 pass to an area 7 where they are heated and then to an area 8 where they come into contact with one another, making the bond, and producing the flocked profile .

In the example shown, the flocked tape 6 has been previously cut to the desired width (which, typically for the application shown in the example, ranges from 5 to 30 mm) , and enters the flocking area 5 from a motorized unwinder 9 which unwinds a spool of tape 6 so that the linear advance speed of the tape 6 is equal to the extrusion rate of the profile .

The flocked tape 6 (see figures 2 and 3 ) is of the type available commercially . The tape comprises a flocked side 10 on a base 11 intended to come into contact with the surface of the profile . The base 11 comprises an olefinic compound which is chemically compatible with one of the EPDM polymers of the profile, for example ethylene, which guarantees that , if we heat the surface 11 of the tape 6 to a temperature close to the melting point of the olefinic compound and we heat the surface of the EPDM profile appropriately, they bond by simple contact , as can be observed diagrammaticalIy in figure 4 , in which the contact has been represented by arrows A, and the temperature by wavy lines B . That is, there is no intermediate adhesive

between the base 11 and the profile 1 ; they are bonded directly to one another .

The heating temperature of the surface of the EPDM profile 1 should be in the order of the melting temperature of the polymer which will achieve the bond with the olefinic component of the base 11 of the tape , but in any case lower than the degradation temperature of the EPDM .

Depending on the composition and structure of the profile material , the present embodiment provides for the addition, as an additive to the EPDM composition, of an olefinic compound compatible with the present flocked tape 6 to favour the bond between profile and tape .

Figures 5 to 8 show an EPDM profile intended to serve as a seal in a window 1 with a sliding pane , produced using the procedure of figure 1. In the detail of figure 8 it can be observed that the rubber profile 1 is characterized in that it has a rubber profile joined to a flocked tape 6 comprising a base 11 which has a flocked side 10 , the tape 6 being tightl y bonded to the profile without the presence of an adhesive between both components . As a consequence of this composition, it can be observed that the hairs of the flocked surface 10 are essentially perpendicular to the surface throughout .