A LABEL FOR A TYRE OF VEHICLE WHEELS, A PROCESS FOR MANUFACTURING SAID LABEL AND A PROCESS FOR MANUFACTURING A TYRE INCLUDING SAID LABEL

Abstract

A label (1; 50) for a tyre (100) of vehicle wheels comprises: an external surface (2) which is intended to remain visible when said label (1; 50) is coupled to a sidewall (102) of the tyre, an internal surface (3) which is opposite the external surface (2), a plurality of recesses (10) which are formed at the external surface (2) and which are not open at said internal surface (3) and which are capable of generally defining at least one portion of information which is set out on the label. The plurality of recesses (10) are formed on a first layer (4) of the label (1; 50) which is made of an elastomer material which is compatible with the elastomer material of the sidewall (102). The first layer (4) is partially vulcanized and has a degree of vulcanization corresponding to a value between T.sub.30 and T.sub.60.

Claims

1. A label (1; 50) for a tyre (100) of vehicle wheels comprising: an external surface (2) which is intended to remain visible when said label (1; 50) is coupled to a sidewall (102) of said tyre, an internal surface (3) which is opposite said external surface (2), a plurality of recesses (10) which are formed at said external surface (2), which are not open at said internal surface (3) and which are capable of generally defining at least one portion of information which is set out on said label, wherein said plurality of recesses (10) are formed on a first layer (4) of said label (1; 50) which is made of an elastomer material which is compatible with the elastomer material of said sidewall (102), and wherein said first layer (4) is partially vulcanized and has a degree of vulcanization corresponding to a value between T.sub.30 and T.sub.60.

2. A label according to claim 1, wherein said first layer (4) is partially vulcanized and has a degree of vulcanization corresponding to a value between T.sub.40 and T.sub.50.

3. A label according to claim 1 or claim 2, having a thickness (S) between 0.5 and 1.5 mm.

4. A label according to any one of the preceding claims, wherein said recesses (10) have a depth between 40% and 80% of the thickness (S) of said label (1; 50).

5. A label according to any one of the preceding claims, wherein said recesses (10) are substantially identical.

6. A label according to any one of the preceding claims, wherein said recesses (10) have a substantially frustoconical profile which tapers from said external surface (2) towards the inside of said first layer.

7. A label according to any one of the preceding claims, wherein said recesses (10) form a QR code.

8. A label according to any one of the preceding claims, wherein said elastomer material from which said first layer (4) is produced is the same elastomer material of which said sidewall (102) of the tyre is made.

9. A label according to any one of the preceding claims, wherein said elastomer material of which said first layer (4) is made comprises a fraction of halogenated isobutylene polymer greater than 5 phr.

10. A label according to claim 9, wherein said elastomer material of which said first layer (4) is made comprises a diene polymer and said halogenated isobutylene polymer at a weight ratio between 20/80 and 80/20.

11. A label according to any one of the preceding claims, wherein said elastomer material of which said first layer (4) is made comprises a vulcanizing agent in a quantity between 0.3 and 3.0 phr.

12. A label according to any one of the preceding claims, wherein said elastomer material of which said first layer (4) is made comprises antioxidant agents in a quantity between 1 phr and 10 phr.

13. A label (1) according to any one of the preceding claims, wherein said first layer (4) defines both said external surface (2) and said internal surface (3) of said label (1).

14. A label (50) according to any one of claims 1 to 12, wherein there is provided a second layer (6) of elastomer material which is coupled to said first layer (4) at the side opposite said external surface (2).

15. A label according to claim 14, wherein said second layer (6) has a different colouration from that of said first layer (4) and said recesses (10) are formed in said first layer (4) as through-recesses so as to make said second layer (6) visible.

16. A process for manufacturing a label (1; 50) according to any one of the preceding claims, comprising: providing at least a first layer (4) of green elastomer material; partially vulcanizing said first layer (4) in order to obtain a degree of vulcanization corresponding to a value between T.sub.30 and T.sub.60; forming on an external surface (2) of said first layer (4) a plurality of recesses (10) which are generally capable of defining at least one portion of information which is set out on said label, said recesses not being open at an internal surface (3) of said label opposite said external surface.

17. A process according to claim 16, wherein, before being partially vulcanized, said first layer (4) is coupled to a support film (5) at the side opposite said external surface (2).

18. A process according to claim 16 or claim 17, wherein said partial vulcanization is obtained by heating said first layer (4) to a temperature between 140° C. and 200° C., preferably between 150° C. and 170° C.

19. A process according to any one of claims 16 to 18, wherein said recesses (10) are obtained by means of laser processing.

20. A process for manufacturing a tyre for vehicle wheels comprising: building a green tyre (100), applying to a sidewall (102) of said green tyre a label (1; 50) according to any one of claims 1 to 15, moulding and vulcanizing said green tyre (100) in a mould so as to complete the vulcanization of said label (1; 50) and to fix said label (1; 50) to said sidewall (102).

Description

[0128] The features and advantages of the invention will be better appreciated from the detailed description of a number of preferred embodiments thereof, which are illustrated by way of non-limiting example with reference to the appended drawings, in which:

[0129] FIG. 1 is a schematic, perspective front view of a first embodiment of a label for tyres of vehicle wheels which is constructed according to the present invention;

[0130] FIG. 2 is a schematic, longitudinal section along the line II-II of a portion of the label of FIG. 1;

[0131] FIG. 3 is a schematic side view of a portion of a sidewall of a vulcanized tyre which is provided with the label of FIG. 1;

[0132] FIG. 4 is a schematic, longitudinal section of a second embodiment of a label for tyres of vehicle wheels which is constructed according to the present invention.

[0133] With initial reference to FIGS. 1 to 3, there is generally designated 1 a first embodiment of a label for tyres of vehicle wheels which is constructed according to the present invention.

[0134] The label 1 is provided to be applied to a tyre 100, with a structure and configuration which are conventional per se.

[0135] Therefore, the tyre 100 has a generally toroidal form which extends about a rotation axis and which comprises in a radially external position a tread band 101 which comprises elastomer material and on which there is defined a tread surface which is intended for contact with a road surface, and a pair of sidewalls 102 which also comprise a layer of elastomer material and which extend from the ends of the tread band towards the rotation axis.

[0136] In particular, the sidewalls 102 comprise a layer of elastomer material with a thickness of approximately from 2 to 5 mm, the composition of which is conventional per se.

[0137] By way of example, the elastomer material of the sidewalls 102 may therefore comprise: [0138] BR rubber (polybutadiene) of approximately 45 phr; [0139] NR rubber (natural rubber) of approximately 55 phr; [0140] carbon black of approximately 45 phr; [0141] mineral oil (for example, TDAE oil “Treated Distillated Aromatic Extract” of approximately 10 phr; [0142] anti-oxidant agents of approximately 6 phr; [0143] sulphur-based vulcanizing agents of approximately 1.3 phr; [0144] accelerating agents of approximately 0.7 phr.

[0145] The label 1 has a plate-like configuration, extending along two main dimensions and having a third dimension (the thickness) of a lower order.

[0146] Therefore, there is defined on the label 1 a pair of main opposing surfaces with a substantially similar shape.

[0147] In particular, the main surfaces define an external surface 2 of the label 1 which is intended to remain visible when the label 1 is coupled to a sidewall 102 of the tyre 100 and an internal surface 3 opposite the external surface 2, respectively.

[0148] The external surface 2 and the internal surface 3 have a generally quadrangular shape with rounded vertices, with sides L1, L2 having dimensions between 15 and 40 mm, while the thickness S of the label 1 is between approximately 0.5 and 1.5 mm.

[0149] In the preferred example described herein, the external and internal surfaces 2 and 3 have a substantially square shape with sides of approximately 20 mm, while the thickness of the label 1 is approximately 1 mm. However, the label 1 may have a shape and dimensions which are different in accordance with the information set out thereon and other possible production requirements.

[0150] The label 1 has a dark grey colouration substantially identical to that of the sidewall 102.

[0151] There are formed at the external surface 2 a plurality of recesses 10 which are generally capable of defining an information item set out on the label 1.

[0152] In particular, the recesses 10 are substantially mutually identical and generally define a QR code, on which different information items are set out in relation to the tyre 100, such as, for example, the model, dimensions, load index, speed index, etc.

[0153] In particular, the recesses 10 have a substantially frustoconical profile which tapers from a respective base thereof, which is open at the external surface 2, towards the interior of the label 1.

[0154] The base of each recess is substantially circular and has a diameter between 0.4 and 0.5 mm.

[0155] The recesses 10 are blind-holes, that is to say, they are not open at the internal surface 3, and extend inside the label 1 up to a depth of from 0.5 to 0.7 mm, for example, approximately 0.6 mm.

[0156] In other construction variants, the recesses may have mutually different shapes and may be specifically configured to define alphanumerical characters or a design or a logo.

[0157] The recesses 10 are formed in a first layer 4 of the label 1.

[0158] In particular, in the first embodiment illustrated in FIGS. 1 to 3, the label 1 is formed only by the first layer 4, thus having chemical/physical characteristics which are substantially homogeneous.

[0159] The first layer 4 (and consequently the entire label 1) is made from an elastomer material which is compatible with the elastomer material of the sidewall 102 to which the label 1 is intended to be applied. Furthermore, the elastomer material from which the first layer 4 is constructed is partially vulcanized, having a degree of vulcanization corresponding to a value between T.sub.40 and T.sub.50, as defined by means of the international standard ASTM D5289.

[0160] In particular, the elastomer material from which the first layer 4 is constructed comprises an elastomer matrix based on natural rubber (NR) and bromo-isobutylene polymer at a ratio by weight of approximately 1:1 (50 phr of NR and 50 phr of bromo-isobutylene polymer), suitably supplemented with carbon black of a grade ASTM N660 and silica for an overall quantity of approximately 50 phr, and with approximately 1 phr of antioxidant agent Vulkazon AFS, in addition to a vulcanizing agent based on sulphur (approximately 1 phr) and accelerating compounds for the vulcanization.

[0161] The label 1 is obtained in the manners described below.

[0162] The elastomer compound described above, which is not vulcanized, is subjected to calendering in order to obtain a semi-processed product which is formed by a homogeneous layer of elastomer compound having a desired thickness, in this case of approximately 1 mm, and a suitable length and width, for example, between 0.5 and 2 metres, which are defined by production requirements and the characteristics of the calendering apparatus.

[0163] During the calendering, the layer of elastomer compound is further coupled to a support film 5, preferably of PET, at one of the main surfaces thereof. The main surface to which the support film 5 is coupled (indicated in FIG. 2 with broken lines and in a partially raised position) is intended to become the internal surface 3 of the label 1.

[0164] After the calendering, the semi-processed product is heated to a temperature of approximately from 150° C. to 170° C. for a time between 2 and 4 minutes so as to obtain a degree of cross-linking of the elastomer compound corresponding to a value between T.sub.40 and T.sub.50.

[0165] After the partial vulcanization, there are formed on the main surface of the semi-processed product opposite the support film the plurality of recesses 10 which define the information item to be set out on each label 1 obtained by the semi-processed product. In particular, the recesses are formed by means of laser processing and form a plurality of QR codes which are distributed on the semi-processed product in a suitable manner.

[0166] At the end of this step, the semi-processed product is cut so as to obtain a respective label 1 for each plurality of recesses 10.

[0167] Each label 1 is therefore ready to be applied to a sidewall 102 of a green tyre 100.

[0168] In particular, the label 1, after the support film 5 has been detached, is applied to the sidewall 102 just before the tyre is inserted in a vulcanization mould.

[0169] As a result of the action of the temperature and the pressure present inside the vulcanization mould, the label 1 is integrated in the sidewall 102, also completing the vulcanization of the elastomer compound thereof. Particularly during this step, there also occurs the formation of cross-linking bridges between the elastomer compound of the label 1 and the elastomer compound of the sidewall 102, improving the adhesion and integration of the label 1 in the sidewall 102.

[0170] FIG. 4 illustrates a second embodiment of the label according to the present invention which is generally designated 50 and in which similar components to the first embodiment are indicated with the same reference numerals.

[0171] Similarly to the label 1, the label 50 also comprises an external surface 2, an opposite internal surface 3 and a plurality of recesses 10 which are formed on the external surface 2, but without passing through the label over the entire thickness thereof, and open at the internal surface 3.

[0172] The label 50 differs from the label 1 mainly in that it also comprises, in addition to the first layer 4, a second layer 6 which is coupled to the first layer 4 at the side opposite the external surface 2 of the label 50.

[0173] In this manner, the first layer 4 comprises the external surface 2 while the second layer 6 comprises the internal surface 3.

[0174] The second layer 6 comprises an elastomer compound which is substantially identical to that of the first layer 4, but to which there is added a suitable colourant so as to make the colour of the second layer 6 substantially different from that of the first layer 4.

[0175] Furthermore, the recesses 10 extend inside the label 1 over the entire thickness of the first layer 4 until they reach the second layer 6.

[0176] In this manner, the colouration of the second layer 6 is made visible through the recesses 10.

[0177] The label 50 is obtained substantially in the same manner as the label 1, with the difference of the provision of a separate elastomer compound for the second layer 6 which is then obtained and coupled to the first layer 4 in a calendering step.

[0178] The support film 5 is coupled at the side of the second layer 6 and the recesses 10 are formed, for example, by means of laser processing, in such a manner that the second layer 6 is reached.

[0179] The application of the label 50 to the sidewall of a tyre is carried out in the same manners described above in relation to the label 1.

EXAMPLE

[0180] A label obtained according to the first embodiment (label 1) described above has been applied to the sidewall of a green tyre A for motor vehicles, having the elastomer composition indicated above, and moulded and vulcanized together with the tyre in order to fix it thereto (tyre A).

[0181] In a generally similar manner, there is then fixed to a sidewall of a green tyre B (identical to the tyre A) a label which is similar to the label 1 of the first embodiment but which is obtained using the same elastomer compound as the sidewall of the tyre B.

[0182] The tyres A and B obtained in this manner have therefore been subjected to a combined test for fatigue resistance and ageing.

[0183] In particular, each tyre has been inflated to a pressure of approximately 260 KPa and, once mounted on a suitable measuring apparatus, has been rotated in order to simulate a constant speed of 120 Km/h under a weight of approximately 50% of the load index thereof. At the same time, at the sidewall of the tyre to which the label has been applied, there has been supplied a continuous flow of approximately 300 Nl/h of air enriched with ozone (at a concentration of approximately 3 g/m.sup.3) in a confined environment with controlled temperature.

[0184] After 200 hours of operation, the two tyres A and B have been examined.

[0185] In particular, in both the tyres A and B there has been found the substantial absence of cracking, both in the sidewall and in the label, and the complete adhesion of the respective label to the sidewall.

[0186] It has further been found that the colouration of the label and the sidewall were substantially identical in the tyre B, while in the tyre A the label had maintained a colouration very similar to the starting colouration with respect to the sidewall which was instead partially discoloured following the action of ozone.

[0187] The test has proved that both the labels are suitable for being used on the sidewall of a tyre and that the label produced according to the first embodiment is highly resistant to the effects of ageing, even more resistant than the sidewall of the tyre to which it is applied.