The present invention relates to sachets with at least two compartments and methods of manufacture thereof.

The invention relates more particularly but not exclusively to sachets intended for packaging a hair coloring product for use in the home.

Manufacturers of coloring products generally recommend that consumers carry out a spot-test before applying the coloring product on the hair, in order to reveal any undesirable physiological reaction of the skin.

In particular, such a reaction may be associated with an allergy problem.

It is preferable to carry out this test 48 hours before using the coloring product, by applying a drop of the product on the surface of the skin, and notably behind the ear, in order to ascertain later whether this deposit leads to the appearance of reddening, in which case application of the coloring product is not to be recommended.

Hair dyes are usually sensitive to oxygen. In particular, the oxidation dyes used in permanent coloring products react strongly in the presence of oxygen, so that if the drop of product is taken from the same compartment as that containing the composition to be used on the hair, opening the compartment may lead to a change at least in the appearance of the composition, which may lead the consumer to think that the product is faulty.

Application FR 2 918 038 describes a sachet with two compartments that are detachable by being precut. Such a sachet is of relatively complex manufacture.

Application EP 1 669 305 A 1 discloses a sheet material suitable for making sachets containing a hair coloring composition.

Application EP 1 357 047 Al describes a tube, the end of which is provided with a second compartment that can be separated from the rest of the tube.

Application EP 0 639 364 Al and patent US 6 047 817 disclose packaging devices with two compartments.

There is a need to offer the consumer means for carrying out a spot-test but without altering the quality of the coloring product intended to be applied on the hair, and without the proposed solution leading to extra cost or causing logistical problems.

The invention aims to meet this need. According to one of its aspects, the invention relates to a sachet with at least two compartments, comprising:

- a first compartment, containing a composition,

- a second compartment, of smaller capacity than the first, containing the same composition,

the first and second compartments being made by welding two sheets on one another, the compartments being separated by a weld line, the sheets each extending continuously on either side of the weld line for the entire length of the latter, from one compartment to the other.

"Sachet" is to be understood as a flexible pocket excluding the presence of a distributing element such as a capsule or an injection tip, in contrast to a tube.

The invention makes it possible to carry out reliable and economical packaging of two amounts of a product, for example a test quantity and a larger quantity.

The second compartment, of reduced volume, offers the user the possibility of using the composition contained in this second compartment, and to wait the 48 hours required for the test of harmlessness, without the composition contained in the first compartment being altered by the environment; the user can also use the composition contained in the first compartment directly, without bothering with the composition contained in the second compartment.

The invention provides easy opening of each compartment, advantageously without a tool, as one or more tearing starts are provided.

The first compartment is intended to be opened along a first opening line marked on the sachet, preferably adjacent to the weld line.

The second compartment is intended to be opened along a second opening line, marked on the sachet.

At least one, and preferably each of the first and second opening lines, is marked by two tearing starts at its ends, consisting for example of notches cut in the sheets.

The capacity C2 of the second compartment is less than the capacity CI of the first compartment, with for example 0.005≤ C2/C1≤ 0.9, preferably 0.0075≤ C2/C1≤ 0.1. The capacity CI is for example in the range from 10 to 200 ml, and C2 is for example in the range from 0.2 to 10 ml.

The compartments are each delimited entirely by weld lines, which excludes any injected distribution tip.

The composition is preferably a dyeing composition for coloring the hair.

Opening of the first compartment can lead to separation of the two compartments, the second being detached from the sachet completely.

According to another of its aspects, the invention further relates to a method of manufacturing and of filling a sachet, notably as defined above, comprising:

- welding, notably by thermal welding, two sheets to form a sachet having a space open at one end only,

- filling this space with the composition,

- closing the opening in the sachet,

- welding through the composition, notably by ultrasonic welding, to form a weld line and to define two compartments on either side of the latter, the capacities of these two compartments being unequal.

According to another of its aspects, the invention further relates to a method of hair treatment by means of a sachet according to the invention, as defined above, comprising:

- conducting a test with a test quantity contained in the second compartment,

- if the test shows no sign of allergy, applying the contents of the first compartment on the hair.

According to another of its aspects, the invention further relates to the use of a sachet according to the invention, as defined above, for packaging a permanent, semipermanent or temporary coloring product.

The invention may be better understood on reading the detailed description given hereunder, of nonlimiting practical examples thereof, and on examining the appended drawing, in which:

- Fig. 1 shows a front view of an example of a sachet made according to the invention,

- Figs. 2 and 3 are sections respectively along II-II and III-III in Fig. 1, and

- Figs. 4 and 5 are views similar to Fig. 1, of variants of embodiments. The sachet 1 shown in Fig. 1 has a general shape that is elongated along a longitudinal axis X and comprises two sheets 2 and 3, which are assembled along weld lines so as to define a first compartment 5 and a second compartment 7 which contain, in the example being considered, one and the same hair dye. The latter can be a product for permanent dyeing (oxidation dyeing), or a product for semi-permanent or temporary coloring (direct dyeing). Examples of such products are given in the book "Chemical and Physical Behavior of Human Hair", 4th edition, Chapter 6, pages 311 to 344 by Clarence R. Robbins, published by Springer.

In particular, the dyeing composition contained in the sachet can contain one or more oxidation bases and/or one or more couplers conventionally used for dyeing keratin fibers.

Among the oxidation bases, we may mention para-phenylenediamines, bis- phenylalkylenediamines, para-aminophenols, bis-para-aminophenols, ortho-aminophenols, heterocyclic bases and addition salts thereof.

Among the couplers, we may notably mention meta-phenylenediamines, meta- aminophenols, meta-diphenols, naphthalenic couplers, heterocyclic couplers and addition salts thereof.

The dyeing composition can also comprise an oxidizing agent, which can be selected from hydrogen peroxide, urea peroxide, bromates of alkali metals, persalts such as perborates and persulfates, as well as enzymes, among which we may mention peroxidases, oxidoreductases with 2 electrons such as uricases and oxygenases with 4 electrons such as laccases. The use of hydrogen peroxide is particularly preferred.

The dyeing composition can moreover contain additional direct dyes. Such dyes can be used alone or in combination with a dyeing composition such as described above. These direct dyes are for example selected from neutral, acid or cationic direct benzene nitro dyes, neutral, acid or cationic direct azo dyes, tetraazapentamethine dyes, neutral, acid or cationic quinone and in particular anthraquinone dyes, direct azine dyes, direct triarylmethane dyes, direct indoamine dyes and natural direct dyes.

Among natural direct dyes, we may mention lawsone, juglone, alizarin, purpurin, carminic acid, kermesic acid, purpura gallin, protocatechaldehyde, indigo, isatin, curcumin, spinulosin, apigenidin. It is also possible to use extracts or decoctions containing these natural dyes and notably henna-based cataplasms or extracts. Agents beneficial to keratinous materials, or nutritive solution, can also be added to said compositions, and these agents can be selected from:

(1 ) amino acids, oligopeptides, peptides, hydro lyzed or nonhydrolyzed, modified or unmodified proteins,

(2) linear or branched fatty acids and alcohols,

(3) animal, vegetable or mineral waxes,

(4) ceramides and pseudoceramides,

(5) hydroxylated organic acids,

(6) UV filters,

(7) antioxidants and anti-free radical agents,

(8) chelating agents,

(9) anti-dandruff agents,

1 0) agents for controlling seborrhea,

1 1 ) soothing agents,

1 2) cationic surfactants,

1 3) amphoteric polymers,

14) silicones, organomodified or not,

1 5) mineral, vegetable or animal oils,

1 6) polyisobutenes and poly(a-olefms),

1 7) esters,

1 8) soluble or dispersed anionic polymers,

1 9) soluble or dispersed nonionic polymers,

and mixtures thereof.

The first compartment 5 extends along the X axis, which is a longitudinal axis X for this compartment, on a length L and its width decreases towards an upper end to define a neck 9 which serves for distributing the contents of this compartment, and this neck 9 can be opened by cutting the sachet along a transverse opening line 10. The second compartment 7 extends as a prolongation of the first compartment 5, above the neck 9.

The capacity of the first compartment 5 is for example 100 ml and that of the second 0.5 ml. Notches 11 and 12 can advantageously be made at the ends of the opening line 10, as illustrated, so as to create a start for tearing and to facilitate opening of the sachet. These notches 11 and 12 mark the location of the opening line 10 for the user.

The neck 9 defines a distribution opening 26, of width / less than the width w of compartment 5 under the neck 9. We have for example O < / < w/3.

Sheets 2 and 3 are welded together on lines 20 along the edges of the sachet, at the bottom 21 of the sachet 1 and on portions 22 defining the neck 9.

Compartment 5 is closed above the opening line 10 by a weld along a weld line 23, which separates compartments 5 and 7.

In the example shown, the width of compartment 7 is less than or equal to the width / of the opening 26 and decreases with increasing distance from the latter as far as a transverse opening line 30 allowing access to the contents of the second compartment 7.

Notches 31 and 32 are advantageously made at the ends of the opening line 30. These notches 31 and 32 mark the location of the opening line 30 for the user. In the example shown, opening lines 10 and 30 are parallel to one another and to the weld line 23 which is between them.

The sheets 2 and 3 are welded on portions 38 along the second compartment 7, and above the latter at 39.

As can be seen notably in Fig. 3, each sheet 2 or 3 extends continuously on either side of the weld line 23 on passing from one compartment to the other. In other words, there is no cut in sheet 2 or 3 between compartments 5 and 7, in contrast to the sachet disclosed in FR 2 918 038 where the compartments are separated by cuts made in the sheets that were used for making the sachet. The absence of such cuts facilitates filling of the sachet, which can be carried out using a single filling tube, as described in detail later. In the example in Fig. 1, the only cuts made are those that give the sachet its external contour.

If the user is trying composition C for the first time, he tears the second compartment at the level of the corresponding start for opening consisting of notch 31 or 32, takes the required amount of composition from this compartment, and deposits it where required, behind the ear for example. After the prescribed time, 48 hours for example, and in the absence of immune reaction, he opens the first compartment 5 at the level of the corresponding start for opening, namely notch 11 or 12, and applies the product.

If the user has already carried out a test with this same composition C, he opens the first compartment 5 directly at the level of notch 11 or 12, and applies the product.

Opening of the first compartment 5 can lead to separation of compartments 7 and 5, compartment 7 being detached from the sachet completely.

The sachet 1 can be made and filled as follows.

The two sheets 2 and 3 are assembled by thermal welding, said sheets being for example such as described in European patent application EP 1 669 305, each having a multilayer complex, where said complex can comprise a metallic layer, for example of aluminum, an adhesive agent, for example a copolymer of ethylene and acrylic acid, and a layer of nonmetallic material, for example PE, bonded to the metallic layer via the adhesive agent. Each sheet preferably has a thickness less than or equal to 250 μιη.

The two sheets 2 and 3 of multilayer material are arranged opposite one another, weldable part against weldable part, and welded together by thermal welding so as to close the sachet, leaving a part open. This open part can be situated on the side opposite the neck 9, but also on one of the lateral sides parallel to the X axis.

A tube of a device for filling the composition is inserted through this open part, and the composition is injected.

After withdrawal of the filling device, thermal welding closes the sachet completely hermetically, while giving it the desired final shape.

Then additional welding is carried out along the weld line 23 to form and separate the two compartments 5 and 7. This additional welding is of the type that permits welding through the composition without degrading it, preferably ultrasonic welding.

The two manufacturing steps are carried out one after other, without breaking the production chain.

The invention is not limited to the example that has just been described.

For example, to facilitate opening of the two compartments 5 and 7, in the welded zone delimiting each of these two compartments, the notches 11, 12, 31 and 32 can be replaced with any other known device for easy opening, for example in the case of sheet of multilayer composite material, a precut of the outer layer, without reaching the aluminum layer.

A sachet according to the invention makes it possible to offer safety for the user, has a smaller carbon footprint than an aluminum tube as used at present, is of lower cost price than such a tube or a sachet such as presented in FR 2 918 038, and is much simpler to produce industrially.

The shape of the sachet as well as of the first and second compartments can be varied while remaining within the scope of the present invention.

Thus, Fig. 4 shows a variant where the sachet 1 has a constant width on its entire height, apart from the notches 11, 12, 31 and 32.

In the variant in Fig. 5, the second compartment 7 is made in a corner of the sachet 1.

The opening lines 10 and 30 thus extend obliquely relative to the longitudinal axis X. The sachet 1 has for example a rectangular contour. The weld line 23 extends obliquely, parallel to the opening lines 10 and 30.

Compartment 5 is delimited at the top by a weld line 50, perpendicular to the longitudinal axis X. Compartment 7 is also delimited at the top by this line 50 and laterally by the adjacent line 20.

The expression "comprising a" must be understood as being synonymous with "comprising at least one", unless stated otherwise.