APPARATUS FOR SHAPING HAIR

Abstract

Apparatus (1) for shaping hair, comprising: two arms (3, 4) that are able to move with respect to one another and are able to assume a spaced-apart configuration for introducing a lock of hair between them and a moved-together configuration for treating the lock of hair, the arms (3, 4) being movable along the lock in this moved-together configuration,two contact surfaces (5, 6) borne by the two arms (3, 4), respectively, arranged facing one another, at least one of the contact surfaces (5, 6) being a heating surface,at least one strip (12, 12a, 12b, 12c, 12d) made of a friction material comprising a silicone elastomer, a fluoroelastomer or a perfluoroelastomer, and attached to each of the contact surfaces (5, 6) so as to protrude from the contact surface (5; 6) to which it is attached by a height (H) that is strictly greater than 0 mm even in the moved-together configuration of the arms (3, 4) and smaller than 2 mm.

Description

TECHNICAL FIELD

The present invention relates to an apparatus for shaping hair, in particular for hair relaxing and/or straightening operations.

PRIOR ART

Numerous apparatuses for shaping hair, in particular straightening irons, tongs or hair straighteners, are known, as described, for example, in US 2009/044823.

Usually, hair straighteners consist of two arms that are connected together with the aid of a hinge that makes it possible to open and close said arms and of a heating device comprising at least one heating element arranged on the arms. During operations for treating a lock of hair, the latter is introduced between the two arms in the open position and then the two arms are closed manually over the lock of hair. This lock is then subjected to the heat emitted by the heating element, until the two arms are opened and the lock of hair is removed.

To obtain better shaping results, the heating element may be combined with at least one comb, which might or might not be a heating comb, which allows the strands of hair to be separated as they pass between the arms and friction to be applied in order to bring about more uniform results. An apparatus of this type is, for example, described in application FR 2 940 894, the apparatus comprising a friction bar that is mounted movably with respect to the straightening surface and able to interact with a friction counter-bar when the arms are in the closed position, thereby defining a tensile region that creates a tensile force greater than the tensile force created by the treatment region as the apparatus is moved over a lock of hair.

WO 2017/089152 discloses a device for shaping hair comprising a heating plate for heating the hair, a temperature sensor and a heat control circuit, the surface of the heating plate potentially comprising a silicone strip. Similar devices are described in CN 207152182 and CN 207270050.

The known apparatuses are not entirely satisfactory when it comes to obtaining sufficient friction between the lock of hair and the heating device during shaping which leads to insufficient hair alignment.

There is therefore a need for a hair-shaping apparatus that allows better shaping, and in particular more effective and uniform straightening, to be obtained.

DISCLOSURE OF THE INVENTION

The invention aims to meet this need entirely or in part, and it does so by virtue of an apparatus for shaping hair, comprising:

• • two arms that are able to move with respect to one another and are able to assume a spaced-apart configuration for introducing a lock of hair between them and a moved-together configuration for treating the lock of hair, the arms being movable along the lock in this moved-together configuration,
  • two contact surfaces borne by the two arms, respectively, arranged facing one another, at least one of the contact surfaces being a heating surface,
  • at least one strip made of a friction material comprising a silicone elastomer, a fluoroelastomer or a perfluoroelastomer, and attached to each of the contact surfaces so as to protrude from the contact surface to which it is attached by a height that is strictly greater than 0 mm even in the moved-together configuration of the arms and smaller than 2 mm, said at least one strip attached to one of the contact surfaces being arranged so as to be offset with respect to said at least one strip attached to the other of the contact surfaces in the moved-together configuration of the arms.

By virtue of the invention, with the addition of friction created by each strip, the movement of the apparatus relative to the lock of hair may be slowed down which allows more uniform and more effective straightening of the hair to be obtained.

The term “hair” encompasses human or corresponding animal, but preferably human, keratin fibers and also synthetic fibers known as “extensions” which are sometimes added to an individual's natural head of hair by various means, especially by adhesive bonding, in order for example to modify the appearance of an individual's natural head of hair and the synthetic or non-synthetic fibers of a wig.

What is meant by “contact surface” is a surface for treating hair, preferably a straightening surface, for example formed by a straightening plate, which is advantageously a heating plate, as will be described hereinafter. Each treatment surface is intended to come into contact with at least one lock of hair during the hair treatment. The contact surfaces are preferably planar and arranged parallel to one another in the moved-together configuration. The contact surfaces may be made of an inorganic material, for example a metal or a ceramic, being made, for example, of anodized aluminium or of aluminium with a ceramic surface treatment.

Said at least one strip is preferably not movable relative to the contact surface to which it is attached. It should be noted that it has a specific elasticity depending on the friction material used. It preferably has a continuous and planar friction surface, in particular one that is free of reliefs, for example free of teeth.

The height by which said at least one strip protrudes is preferably between 0.5 and 2 mm, preferably substantially equal to 1 mm, in the spaced-apart configuration of the arms.

The silicone elastomer might or might not be fluorinated. The silicone elastomer is, in particular, chosen from the group formed of vinyl methyl silicone (VMQ), poly vinyl methyl silicone (PVMQ), fluoro vinyl methyl silicone (FVMQ) and methyl silicone (MQ), preferably vinyl methyl silicone (VMQ).

The fluoroelastomer (FKM) belongs, for example, to the ranges marketed under the names Viton® by Chemours Company, Tecnoflon® by Solvay and Kalrez® by DuPont. The perfluoroelastomer (FFKM) belongs, for example, to the ranges marketed under the names Tecnoflon® and Kalrez®.

These materials (silicone elastomer, fluoroelastomer and perfluoroelastomer) which may form the friction material are elastic. They are also able to withstand continuous use at more than 230° C.

Said at least one strip is preferably free of any material other than the friction material. In particular, said at least one strip may consist entirely of a synthetic polymer and be free of any mineral or multi-mineral element or infrared powder.

The friction material preferably has a Shore A hardness of between 40 and 90 Shore A, in particular substantially equal to 70 Shore A.

The clamping force of the arms in the moved-together configuration, i.e. the pinching force exerted when using the apparatus on a lock of hair, this lock of hair being engaged between the arms in the moved-together configuration, may be between 10 N and 30 N, being, for example, equal to 10 N, 20 N or 30 N. The tension of the lock of hair may be between 9.5 N and 12.5 N for a clamping force of 30 N and a temperature of said at least one surface equal to 200° C. The speed at which the lock of hair passes through the apparatus is preferably about 1.8 cm/s.

The width of said at least one strip may be between 0.5 mm and 10 mm, in particular between 1 mm and 5 mm, preferably between 1 mm and 2 mm, preferably being substantially equal to 1.9 mm.

Said at least one strip may take any shape, for example a sinusoidal shape. As a variant, said at least one strip has a friction surface of rectilinear longitudinal axis, in particular rectangular in shape, extending preferably longitudinally along an axis parallel to a longitudinal axis of the contact surface to which it is attached.

The friction surface of said at least one strip advantageously covers an area smaller than 50% of the surface area of the contact surface to which it is attached, preferably smaller than 40%, more preferably smaller than 20%.

In one particular embodiment, one of the contact surfaces comprises a single strip and the other of the contact surfaces comprises two strips that are arranged so as to flank the single strip in the moved-together configuration of the arms.

In this case, the single strip may be arranged equidistantly from the lateral edges of the contact surface to which it is attached, and the two strips are respectively attached with the same distance from the lateral edges of the contact surface to which they are attached.

In another embodiment, each contact surface comprises two strips.

When at least one of the contact surfaces comprises two strips, these extend advantageously parallel to one another.

Said at least one strip may extend heightwise along an axis perpendicular to the contact surface to which it is attached.

Said at least one strip may take the shape of a parallelepiped of substantially square or rectangular cross section.

As a variant, said at least one strip has a substantially trapezoidal cross section, with a width of the friction surface of said at least one strip intended to come into contact with the lock of hair that is smaller than the width of the surface opposite thereto.

In this case, the edges of said at least one strip each form, with the friction surface, an angle of between 5° and 30°, preferably between 10° and 20°, the angle formed between one of the edges and the friction surface of said at least one strip preferably being equal to the angle formed between the other of the edges and the friction surface of said at least one strip.

In one particular embodiment, each contact surface may comprise at least one groove for accommodating said at least one strip. In this case, said at least one groove may have a substantially trapezoidal cross section, with a width that decreases from the bottom in the direction of the opening of the groove. The exterior shape of the portion of the strip that is accommodated in the groove may be designed to conform to the shape of the groove. The strip may slip into the groove or be force-fitted into the groove.

In another embodiment, said at least one strip is attached to the contact surface as an overthickness, in which case the contact surface may be free of any relief for accommodating said at least one strip. In this case, a surface treatment with the deposition of a thin layer of friction material may be envisaged to produce such a strip.

In this case, said at least one strip may be attached to the contact surface by bonding the friction material or by way of a coating process. What is meant by “coating process” is a process comprising the spraying of a deposit in non-polymerized form onto the contact surface and then heating or irradiating this deposit so as to polymerize it into the friction material in order to attach it to the contact surface.

The apparatus is preferably a straightening iron.

The apparatus preferably comprises a heating device so as to heat said at least one contact surface, which is a heating surface. The overall heating power of the apparatus may be between 50 W and 200 W.

The apparatus may comprise a steam-issuing device that may be used, in particular, when passing the lock of hair between the contact surfaces.

The apparatus may comprise one or more combs, which might or might not be removable.

Another subject of the invention, according to another aspect thereof, is a process for treating hair implementing the apparatus as defined above and comprising the steps of introducing a lock of hair between the arms in the spaced-apart configuration thereof, applying a clamping force to the arms so that they transition to the moved-together configuration while pinching the lock of hair and exerting a clamping force, and then moving the apparatus relative to the lock of hair, preferably in the direction from the roots to the ends of the hair. The process may comprise reiterating the steps mentioned until the hair, or a portion thereof, has been treated.

The treatment process is preferably implemented at a temperature of said at least one contact surface, which is a heating surface, of between 120° C. and 235° C., better between 150° C. and 230° C.

The clamping force of the arms in the moved-together configuration while pinching the lock of hair may be between 10 N and 30 N, being, for example, equal to 10 N, 20 N or 30 N. The tension of the lock of hair may be between 9.5 N and 12.5 N for a clamping force of 30 N and a temperature of said at least one heating contact surface equal to 200° C. The speed at which the lock of hair passes through the apparatus is preferably about 1.8 cm/s.

The treatment process may be carried out with or without the use of at least one cosmetic composition which may be applied before, during or after the shaping of the hair, but preferably before. The treatment process advantageously consists in straightening the hair.

The treatment process may further be implemented in the presence of steam, for example originating from the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood more clearly on reading the following detailed description of non-limiting implementation examples thereof and on examining the appended drawing, in which:

FIG. 1 schematically shows, in perspective, one example of an apparatus for shaping hair according to the invention,

FIG. 2 schematically shows, in perspective, the apparatus of FIG. 1,

FIG. 3 schematically shows a view from below, in perspective and with one arm in partial cross section, of the apparatus of FIG. 1,

FIG. 4 is a schematic and partial cross-sectional view of the apparatus of FIG. 1,

FIG. 5 is a schematic perspective view of the apparatus of FIG. 1,

FIG. 6 shows the same perspective view as FIG. 5, in partial cross section,

FIG. 7 shows the same perspective view as FIG. 5, in another partial cross section with respect to FIG. 6,

FIG. 8 schematically shows, in isolation and in perspective, a heating device for the apparatus of FIG. 1,

FIG. 9 shows the apparatus of FIG. 1 in longitudinal section,

FIG. 10 schematically shows, in perspective, the apparatus of FIG. 1 with the arms in the moved-together configuration,

FIG. 11 schematically shows a front view of the apparatus of FIG. 1 in the configuration of FIG. 10,

FIG. 12 schematically shows, in cross section, the view of the apparatus of FIG. 11,

FIG. 13 schematically shows, in isolation, a front view of two contact surfaces of another example of an apparatus according to the invention, and

FIG. 14 partially and schematically shows, in cross section, another example of a strip that may be used in the apparatus according to the invention.

DETAILED DESCRIPTION

In the rest of the description, elements that are identical or have identical functions bear the same reference signs. For the sake of conciseness of the present description, they are not described for each of the figures, only the differences between the embodiments being described.

A handpiece 2 of an example of a hair-shaping apparatus 1 is shown in FIGS. 1 to 12.

This handpiece 2 has two arms 3 and 4 which are movable with respect to one another between a spaced-apart configuration visible in FIG. 1 for introducing a lock of hair between them and a moved-together configuration, shown in FIGS. 10 to 12, for treating the lock of hair.

The arm 3 forms an upper arm and the arm 4 forms a lower arm in this example. They are connected to one another at one end by a joint 8, the handpiece 2 thus forming tongs.

The arms 3 and 4 define respective half-handles 10 and 11 on which the user may press in order to move the arms 3 and 4 together so as to make them go from the spaced-apart configuration to the moved-together configuration.

An elastic return member (not visible) is preferably provided to return the arms 3 and 4 to the spaced-apart configuration, this elastic return member being, for example, a spring arranged around a pin of the joint 8.

The invention is not limited to one particular way of connecting the arms 3 and 4 together. They may be made movable in another way without departing from the scope of the present invention. However, the presence of a joint is greatly preferred for the ergonomics that it affords.

The arms 3 and 4 each bear, in an end portion opposite the joint 8, a contact surface 5 and 6, respectively. The contact surfaces 5 and 6 face one another, being arranged opposite one another. At least one of the contact surfaces, in the example illustrated both contact surfaces 5 and 6, is (are) heating surfaces. The contact surfaces 5 and 6 form an outer surface of two plates 7 and 9, respectively, of substantially rectangular shape which will be presented further below.

The arms 3 and 4 extend along respective longitudinal axes X and Y. The contact surfaces 5 and 6 take the shape of a rectangle that is elongated along these same respective longitudinal axes X and Y.

The arms 3 and 4 define between them, with the contact surfaces 5 and 6, a region for treating the hair, said region being intended to receive a lock of hair to be treated, the handpiece 2 being moved along said lock of hair during the treatment, for example in the direction from the root to the end of the hair.

In the example in question, the handpiece 2 is configured to carry out a heat treatment on the hair by contact with the two heating contact surfaces 5 and 6.

The direction of movement of the handpiece 2 over the hair is preferably substantially perpendicular to the arms 3 and 4.

The handpiece 2 may be connected, on the joint 8 side, by a line (not visible in the example in question) to a base station (not shown) that is fixed during the treatment and is connected to the mains, or may be connected directly to the mains.

This base station supplies power to the handpiece 2 and may also carry out additional functions of processing electrical signals received from the handpiece 2. The line that connects the handpiece 2 to the base station may thus comprise various electrical conductors.

A user interface (not shown in the figures) may be present on the handpiece 2 so as to allow the user, for example, to start up or not to start up certain components thereof.

According to the invention, at least one strip 12 made of a friction material is attached to each of the contact surfaces 5 and 6 so as to protrude from the contact surface 5 or 6 to which it is attached by a height H (visible in FIG. 4 and also in FIG. 11), which is strictly greater than 0 mm even when the arms 3 and 4 are in the moved-together configuration, as can be seen in particular in FIGS. 11 and 12, and smaller than 2 mm. Said at least one strip 12 attached to one of the contact surfaces 5 or 6 is arranged so as to be offset with respect to said at least one strip 12 attached to the other of the contact surfaces 6 or 5 when the arms 3 and 4 are in the moved-together configuration, as can be seen in particular in FIGS. 11 and 12. In the example in question, the contact surface 5 comprises a single strip 12a (visible in FIG. 2 in particular) while the contact surface 6 comprises two strips 12b and 12c (visible in FIGS. 1 and 12, among others), which are arranged on either side of the strip 12a when the arms 3 and 4 are in the moved-together position. The strips 12b and 12c are arranged close to the lateral edges 13 of the contact surface 6, equidistantly therefrom. The strip 12a is arranged at the centre of the contact surface 5.

In the example illustrated, the friction material forming the strips 12 is a silicone elastomer, in this instance vinyl methyl silicone known by the abbreviation VMQ. This friction material has a Shore A hardness of 70 Shore A.

The presence of these strips 12 on the contact surfaces 5 and 6 makes it possible, when the handpiece 2 is moved relative to the lock of hair, to slow the speed of movement down and to obtain better shaping, in particular straightening, results.

The width of the strips 12 is, in this embodiment, the same for the three strips 12a, 12b and 12c and is equal, in this example, to 1.88 mm.

The contact surfaces 5 and 6, made of a metal or ceramic material, in this example of anodized aluminium, take the shape of a rectangle that is elongated along the longitudinal axis of the arms 3 and 4, respectively. In the example illustrated, each strip 12 extends along an axis parallel to the longitudinal axis of the arm 3 or 4. Each strip 12 has a friction surface 23 of rectilinear longitudinal axis, in this example rectangular in shape, and extends over the entire length of the contact surface 5 or 6 to which it is attached. In the example illustrated, the contact surfaces 5 and 6 are planar around the one or more strips 12.

However, each contact surface 5 or 6 comprises one or two grooves 14 extending longitudinally from one longitudinal edge 15 to the other longitudinal edge 16 of the contact surface 5 or 6. Each groove 14 forms a recessed relief and is intended to accommodate a strip 12. The number of grooves 14 in a contact surface is equal to the number of strips present on this contact surface, preferably one or two per contact surface.

In the example illustrated, the grooves 14 have a substantially trapezoidal cross section, as more clearly visible in FIG. 4, with a width that decreases from the bottom 29 of the groove 14 in the direction of the opening 17 of the groove 14.

Each strip 12 is substantially trapezoidal in shape and/or conforms to the substantially trapezoidal shape of the groove 14 in which it is accommodated, projecting from the opening 17 of the groove by a height H, protruding with respect to the corresponding contact surface 5 or 6, as explained above.

The lateral edges 21 and 22 of the strip 12 each form, with the friction surface 23 of the strip, an angle α and β of between 100 and 20° in this example, these two angles α and β being equal to one another in the example illustrated. The trapezium in which the substantially trapezoidal shape of each strip 12 is inscribed is an isosceles trapezium in this example.

The angles of the substantially trapezoidal shapes formed by the strips 12 are slightly rounded, in this example in a more pronounced manner on the bottom 29 side of the groove 14.

The width of the friction surface 23 of the strip is smaller than the width of the opposite surface 24, in contact with the bottom 29 of the groove 14.

Each strip 12 extends heightwise along an axis Z perpendicular to the contact surface 5 or 6 to which it is attached, as illustrated, for example, in FIG. 4.

Still in the example illustrated, the friction surface 23 of the or each strip 12 occupies an area smaller than 20% of the surface area of the contact surface 5 or 6 to which it is attached. In other words, each strip 12 should not occupy an area greater than 20% of the surface area of the contact surface 5 or 6. For example, if there are two strips 12 on one of the contact surfaces, the total area occupied by these two strips 12 could not occupy an area greater than 40% of the total area of the contact surface.

The strips 12b and 12c are parallel to one another in this example.

The strips 12 extend heightwise perpendicularly to the longitudinal axis X or Y of the arm 3 or 4, corresponding to the longitudinal axis of the contact surface 5 or 6, respectively.

It is the friction surfaces 23 of the strips 12 which come into contact with the hair. As a lock of hair passes through when the arms 3 and 4 are in the moved-together configuration, the strips 12 may be squashed to a certain extent, thereby decreasing the height H, which nonetheless remains strictly greater than 0 mm, preferably greater than 0.5 mm, when the arms 3 and 4 are in the moved-together configuration.

In the example illustrated, the contact surface 6 forms the outer surface of the plate 9 forming, in this example, a heating device 25 of the apparatus, more clearly visible in FIGS. 4, 6 and 7, comprising a compartment 26 accommodating a heating element 27 which is electrically connected using electrical wires (not visible), via the line mentioned above, to the base station or to the mains. The compartment 26 and the heating element 27 both take, in this example, a parallelepipedal shape and extend parallel, as can be seen, to the contact surface 6.

The heating device 25 takes, as can be seen in FIG. 4, a shape that allows the incorporation of the grooves 14, with lateral edges 13 of the contact surface 6 that are rectilinear over most of the contact surface 6 but which are rounded moving away from the contact surface 6, and through-openings 28 which flank the compartment 26. The through-openings 28 could be replaced with a solid material instead without departing from the scope of the invention.

In the example illustrated, the contact surface 5 forms the outer surface of the plate 7 forming, in this example, a heating device 30, similar to the heating device 25, comprising a compartment 31 accommodating a heating element 32 which is electrically connected using electrical wires 33 (visible in FIG. 8), via the line mentioned above, to the base station or to the mains. The compartment 31 and the heating element 32 both take, in this example, a parallelepipedal shape and extend parallel, as can be seen, to the contact surface 5. The heating device 30 takes, as can be seen in FIG. 8, a shape that allows the incorporation of the groove 14, with lateral edges 13 of the contact surface 5 that are rectilinear over most of the contact surface 5 but which are rounded moving away from the contact surface 5, and through-openings 34 which flank the compartment 31. The through-openings 34 could be replaced with a solid material instead without departing from the scope of the invention.

During use, a lock of hair is introduced between the arms 3 and 4 in the spaced-apart configuration thereof, a clamping force which may be between 10 N and 30 N, for example 30 N, is applied to the arms 3 and 4 via the half-handles 10 and 11 so as to move the arms 3 and 4 to the moved-together configuration while pinching the lock of hair. Next, the apparatus 1 is moved relative to the lock of hair, preferably in the direction from the roots to the ends of the hair. Needless to say, these steps may be reiterated with other locks of hair until the hair, or a portion thereof, has been treated.

The temperature of the heating contact surfaces 5 and 6 is, for example, equal to 200° C.

The tension of the lock of hair, with the presence of the strips 12, is between 9.5 N and 12.5 N for a clamping force of 30 N. The temperature of said at least one contact surface is equal to 200° C. The speed at which the lock of hair passes through the apparatus is about 1.8 cm/s. For a treated hair length of 27 cm, the speed of movement will be about 15 s.

Needless to say, the invention is not limited to the examples that have just been described.

In the embodiment of FIG. 13, each contact surface 5 and 6 comprises two strips 12, these being arranged in such a way that, when the arms 3 and 4 are in the moved-together configuration, the two strips 12 attached to the contact surface 5 are not superposed onto the strips 12 attached to the contact surface 6. In this example, the distance from one strip 12 to the closest lateral edge 13 of the contact surface is different from the distance from the other strip 12 to the closest lateral edge 13 of the contact surface, whichever contact surface 5 or 6 is considered. In other words, for a given contact surface, the strips 12 are not located equidistantly from the lateral edges 13 closest to this contact surface.

The one or more strips 12 may take a different shape, for example a sinusoidal shape, without departing from the scope of the invention.

The strip 12 may take, in cross section, a rectangular shape, for example, as illustrated in FIG. 14.

The apparatus may be designed to apply steam and/or a cosmetic product to the hair.

The friction material may be a fluoroelastomer or a perfluoroelastomer.

The presence of the strips 12 made of a silicone elastomer, fluoroelastomer or perfluoroelastomer friction material of the apparatus according to the invention makes it possible to obtain satisfactory hair alignment, a smooth hair appearance in terms of ends and length as sought, as well as hair manageability and a smooth feel, which are desired.

Claims

1. An apparatus for shaping hair, comprising: two arms that are able to move with respect to one another and are able to assume a spaced-apart configuration for introducing a lock of hair between them and a moved-together configuration for treating the lock of hair, the arms being movable along the lock in this moved-together configuration,two contact surfaces borne by the two arms, respectively, arranged facing one another, at least one of the contact surfaces being a heating surface,at least one strip made of a friction material comprising a silicone elastomer, a fluoroelastomer or a perfluoroelastomer, and attached to each of the contact surfaces so as to protrude from the contact surface to which it is attached by a height (H) that is strictly greater than 0 mm even in the moved-together configuration of the arms and smaller than 2 mm,one of the contact surfaces comprising a single strip and the other of the contact surfaces comprising two strips that are arranged so as to flank the single strip in the moved-together configuration of the arms.

2. The apparatus according to claim 1, the height (H) by which said at least one strip protrudes being between 0.5 and 2 mm.

3. The apparatus according to claim 1, the silicone elastomer being chosen from among vinyl methyl silicone (VMQ), poly vinyl methyl silicone (PVMQ), fluoro vinyl methyl silicone (FVMQ) and methyl silicone (MQ).

4. The apparatus according to claim 1, wherein the width of said at least one strip is between 0.5 mm and 10 mm.

5. The apparatus according to claim 4, wherein the width of said at least one strip is between 1 and 2 mm.

6. The apparatus according to claim 1, wherein said friction material has a Shore A hardness of between 40 and 90 Shore A.

7. The apparatus according to claim 1, wherein said at least one strip has a friction surface of rectilinear longitudinal axis extending longitudinally along an axis parallel to a longitudinal axis of the contact surface to which it is attached.

8. The apparatus according to claim 1, wherein the friction surface of said at least one strip covers an area smaller than 50% of the surface area of the contact surface to which it is attached.

9. The apparatus according to claim 1, wherein the single strip is arranged equidistantly from the lateral edges of the contact surface to which it is attached, and the two strips are respectively attached with the same distance from the lateral edges of the contact surface to which they are attached.

10. The apparatus according to claim 1, wherein said at least one strip has a substantially trapezoidal cross section, with a width of the friction surface of said at least one strip intended to come into contact with the lock of hair that is smaller than the width of the surface opposite thereto.

11. The apparatus according to claim 10, wherein the edges of said at least one strip each form, with the friction surface, an angle of between 5° and 30°.

12. The apparatus according to claim 1, wherein each contact surface comprises at least one groove for accommodating said at least one strip.

13. A process for treating hair implementing the apparatus according to claim 1, comprising the steps of: introducing a lock of hair between the arms in the spaced-apart configuration thereof,applying a closing force to the arms so that they transition to the moved-together configuration while pinching the lock of hair and exerting a clamping force, and thenmoving the apparatus relative to the lock of hair.