Glue obtained from a magma of expanded polystyrene

Abstract

Adhesive obtained from an expanded polystyrene magma. The invention relates to an adhesive comprising a polystyrene magma and a chlorinated solvent selected from trichloroethylene, tetrachloroethylene, and mixtures thereof. The invention also relates to the process for preparing the adhesive according to the invention. The invention also relates to a bottle containing [Figure for the abstract: None]

Description

Title of the invention: Glue obtained from an expanded polystyrene magma technical field

[0001] The present invention relates to the recovery of expanded polystyrene waste, and in particular the manufacture of glue from expanded polystyrene, and more specifically from a magma derived from expanded polystyrene. Previous technique

[0002] The use of expanded polystyrene is widespread and generates large quantities of expanded polystyrene waste that are difficult to reuse, particularly for food use. To date, two different techniques have been proposed for treating expanded polystyrene waste: its destruction or its recycling.

[0003] The destruction of expanded polystyrene is typically carried out by incineration. This solution is neither economical nor environmentally friendly. Recycling is a preferred alternative.

[0004] Expanded polystyrene can be recycled either mechanically or chemically. Mechanical recycling involves crushing the expanded polystyrene, then compacting it, and finally generating polystyrene granules. Mechanical recycling has the disadvantage of requiring prior cleaning of the expanded polystyrene to be recycled. Furthermore, mechanical recycling requires high pressure and temperature to soften the expanded polystyrene, and is therefore energy-intensive. It should also be noted that expanded polystyrene residues can easily be dispersed during mechanical recycling operations. Moreover, mechanical recycling does not allow for the subsequent use of the recovered polystyrene for food contact, but only for non-food applications such as insulation or appliance packaging.

[0005] Chemical recycling generally consists of depolymerizing polystyrene to recover styrene. The most widely used method for the chemical recycling of expanded polystyrene is thermal depolymerization, or thermolysis, using conventional heat or microwaves. This method involves thermally cracking the polymer and breaking its chains to obtain, in particular, monomers (benzene, toluene, styrene). The yield of aromatic compounds from polystyrene is high. The styrene monomer obtained can then be repolymerized to obtain polystyrene. This method makes it possible to consider Reusing polystyrene for food contact applications is possible. However, thermal depolymerization is energy-intensive and very expensive.

[0006] An alternative method has been described in French patent FR 2 766 832, which relates to a process for transforming expanded polymers, particularly expanded polystyrene, into a flexible, pasty magma resulting from the collapse of the internal structure of the expanded polystyrene, without any chemical modification of the latter. The described process involves treating the expanded polystyrene with a transformation composition comprising a solvent, a non-greasy lubricant, and an alcohol. Various uses of the resulting magma are envisaged, such as the manufacture of various articles, insulation, sealants, or adhesives, without any explanation being provided for their implementation. Description of the invention

[0007] In this context, the Applicant became interested in the valorization of expanded polystyrene waste for the manufacture of an adhesive. More specifically, the invention relates to an adhesive comprising:

[0008] - a polystyrene magma containing at least 70% by weight of polystyrene relative to the weight of the polystyrene magma, said polystyrene being in an amorphous, unexpanded state, and

[0009] - 0.25 kg to 0.40 kg, preferably 0.28 kg to 0.36 kg, of chlorinated solvent per kg of polystyrene magma, the chlorinated solvent being chosen from trichloroethylene, tetrachloroethylene and their mixture.

[0010] The Applicant has found surprisingly that a precise quantity of a particular solvent, mixed with a polystyrene magma, makes it possible to obtain a single-component adhesive with interesting physico-chemical properties, in particular a long time after coating for assembling parts, and a short pressurization time.

[0011] In the context of the invention, the glue may have one or more of the following characteristics, or a combination thereof:

[0012] - the chlorinated solvent is tetrachloroethylene;

[0013] - the polystyrene magma comprises a transformation composition;

[0014] - the transformation composition is present in a content ranging from 15% to 25% in weight, preferably 17% to 20% by weight, relative to the total weight of the polystyrene magma;

[0015] - the transformation composition comprises at least one solvent, at least one lubricant and at least one alcohol;

[0016] - the transformation composition comprises at least one solvent in a content ranging from 92% to 98% by volume, relative to the volume of the transformation composition;

[0017] - the transformation composition comprises a single solvent, which is acetone;

[0018] - the transformation composition comprises at least one lubricant in a content ranging from 1% to 2% by volume, relative to the volume of the transformation composition;

[0019] - the transformation composition comprises a single lubricant which is glycerin;

[0020] - the transformation composition comprises at least one alcohol in a content of from 0.5% to 6% by volume, preferably 1% to 2% by volume, relative to the volume of the transformation composition;

[0021] - the transformation composition comprises an alcohol selected from among the alcohols aliphatic or cycloaliphatic, linear or branched, comprising 1 to 15 carbon atoms, and preferably an aliphatic alcohol, linear or branched, comprising 1 to 10 carbon atoms; and

[0022] - the alcohol is selected from ethanol, propanol, isopropanol, butanol, iso- butanol, sec-butanol and mixtures thereof, preferably among ethanol, isopropanol and mixtures thereof.

[0023] The invention also relates to a method for preparing an adhesive comprising the following steps:

[0024] i) to have a polystyrene magma containing at least 70% by weight of polystyrene, relative to the weight of the magma, said polystyrene being in an amorphous, non-expanded state,

[0025] ii) have a chlorinated solvent selected from trichloroethylene, tetrachloroethylene or a mixture thereof, and

[0026] iii) bring the magma into contact with 0.25 kg to 0.40 kg, preferably 0.28 kg to 0.36 kg, of chlorinated solvent per kg of magma.

[0027] In the context of the invention, the glue preparation process may have one or more of the following characteristics:

[0028] - in step iii), the chlorinated solvent is mixed with the polystyrene magma; and

[0029] - the polystyrene magma is obtained by bringing expanded polystyrene into contact with a transformation composition comprising at least one solvent, at least one lubricant and at least one alcohol.

[0030] The invention further relates to the use of the glue according to the invention, or of the glue obtained according to the process according to the invention.

[0031] Finally, the invention also relates to a bottle containing the glue according to the invention, or the glue obtained according to the process according to the invention. Description of the implementation methods

[0032] The invention relates to the valorization of waste from expanded polystyrene for the manufacture of an adhesive, via the transformation of expanded polystyrene into a polystyrene magma. More specifically, the adhesive comprises a polystyrene magma and a particular chlorinated solvent.

[0033] In the context of the invention, "magma" refers to a thick, pasty, and flexible mass with a consistency similar to that of a resin. Polystyrene magma is obtained by treating expanded polystyrene with a transformation composition, as detailed below, resulting in a collapse of the internal structure of the expanded polystyrene, without chemical modification of the polymer. Thus, polystyrene magma (or simply magma in the following description) comprises polystyrene in an unexpanded and amorphous form.

[0034] In the context of the invention, the polystyrene magma is prepared according to the following successive steps:

[0035] A) have expanded polystyrene parts to be treated,

[0036] B) optionally remove impurities from the expanded polystyrene parts and / or optionally crush or grind the expanded polystyrene parts to obtain expanded polystyrene fragments whose largest dimension is less than 30 cm, preferably less than 20 cm, and even better less than 10 cm,

[0037] C) apply a transformation composition to the expanded polystyrene parts and / or fragments to be treated,

[0038] D) possibly filter the resulting magma,

[0039] E) possibly eliminate, partially or totally, the transformation composition of the magma obtained, and

[0040] F) optionally add the transformation composition.

[0041] In the context of the invention, the magma is obtained from expanded or semi-expanded polystyrene. For the sake of simplicity, the entire description refers to expanded polystyrene, but it is understood that everything described in connection with expanded polystyrene could apply equally to semi-expanded polystyrene or a mixture of expanded and semi-expanded polystyrene.

[0042] Expanded polystyrene can come from various sources, such as insulating panels, appliance packaging, or food packaging, for example. It is understood that, within the scope of the invention, the origin of the expanded polystyrene is not limiting, and that one or more different sources of expanded polystyrene can be used to manufacture the polystyrene magma and then the adhesive according to the invention. Advantageously, it is not necessary to wash the expanded polystyrene prior to its use: it is not It is necessary that the expanded polystyrene be free of impurities for the manufacture of the polystyrene magma that will be used in the glue according to the invention. It is nevertheless possible to eliminate the impurities, either when the polystyrene is still in its expanded form, or in step D when the polystyrene is in its amorphous form, or both.

[0043] Advantageously in step B), the expanded polystyrene pieces are crushed to obtain expanded polystyrene fragments whose largest dimension is less than 30 cm, preferably less than 20 cm, and even better less than 10 cm. It should be noted that the expanded polystyrene fragments are not in granular or pellet form, and that their largest dimension is advantageously greater than 3 cm. It is understood that all the fragments are not necessarily of the same size, and that a typical size distribution is obtained. Although not mandatory, this step facilitates the collapse of the polystyrene in step C (i.e., the transformation of the polystyrene in its expanded form to an amorphous, unexpanded form), and in particular allows for limiting the amount of processing compound required while maintaining a good collapse rate.

[0044] In the context of the invention, the transformation composition used in step C) is as described below in relation to the glue according to the invention.

[0045] The application of the transformation composition can be carried out in various ways, such as, for example, by immersing the expanded polystyrene pieces and / or fragments in the transformation composition, or by spraying the transformation composition onto the expanded polystyrene pieces and / or fragments. Generally, spraying the transformation composition is preferred, as the resulting collapse requires smaller quantities of the composition, thus reducing costs and potentially eliminating the need for a subsequent step of partially removing the transformation composition from the resulting molten mass. Furthermore, the treatment is faster by spraying than by immersion. Immersion in the transformation composition may be preferred when the quantities of expanded polystyrene to be treated are small.

[0046] When spraying the processing composition onto the expanded polystyrene parts and / or fragments, the quantity of processing composition sprayed is determined according to the quantity of expanded polystyrene to be treated. Advantageously, 0.6 kg to 0.9 kg of processing composition per kg of expanded polystyrene to be treated are used, and preferably 0.7 kg to 0.8 kg of processing composition per kg of expanded polystyrene to be treated. According to a particular embodiment, 0.75 kg of processing composition per kg of expanded polystyrene are applied. The mass of magma obtained then corresponds to the sum of the mass of expanded polystyrene to be treated and the mass of the pulverized transformation composition.

[0047] When immersing the expanded polystyrene to be treated (i.e., the pieces and / or fragments of expanded polystyrene to be treated), a sufficient quantity is used to ensure that all of the expanded polystyrene is completely immersed in the processing composition. The exact quantities depend on the container and the amount of expanded polystyrene to be treated and can be easily determined by those skilled in the art. Again, the mass of the resulting magma corresponds to the sum of the mass of the polystyrene to be treated and the mass of the processing composition in which the expanded polystyrene was immersed.

[0048] As detailed above, regardless of the method used to bring the transformation composition into contact with the expanded polystyrene, the latter transitions from an expanded state to an amorphous, unexpanded state. This can be observed through a significant reduction in volume and the formation of a flexible, non-sticky paste. It is indeed important to note that at this stage, the resulting magma is not sticky and could not be used as an adhesive.

[0049] In step D), the magma can be filtered to remove certain impurities. This optional step can be carried out using a hopper or a filter, for example, the diameter or pore size of which can be adjusted by those skilled in the art. It is also possible to apply pressure or vacuum at this stage, using techniques known to those skilled in the art, which will not be detailed here.

[0050] Advantageously, the magma is obtained at ambient temperature and atmospheric pressure.

[0051] In step E), it is possible to partially or completely remove the transformation composition. It is important to note that a minimum amount of the transformation composition must remain in the magma for the production of the glue, so that it does not dry out. Indeed, by completely removing the transformation composition from the magma, the latter becomes solid and is no longer easily handled.

[0052] According to a first preferred embodiment, the transformation composition is not eliminated during step E). Indeed, according to this embodiment, the quantity of transformation composition applied in step C) is sufficient for the transformation of the expanded polystyrene into magma, and is not greater than the quantity of transformation composition that may be present in the magma for the manufacture of the glue, as detailed in this description.

[0053] According to a second preferred embodiment, the transformation composition is partially eliminated. Thus, it is possible to reduce the content of the transformation composition in the magma, thereby enabling the production of the glue.

[0054] Although not preferred, it is nevertheless possible to completely remove the transformation composition from the magma. Once the transformation composition is completely eliminated, the magma is transformed into a solid and is then composed essentially, or even exclusively, of polystyrene. This solid can then be brought back into contact with the transformation composition to obtain magma, and thus regain the characteristic pasty and flexible form of magma. To facilitate the transformation of the solid into magma, it is advantageous to have the solid in the form of fragments or granules: for this purpose, the solid can be broken into pieces and / or crushed.

[0055] The partial or total removal of the processing composition can be achieved by various techniques, such as evaporation or dewatering. Evaporation can be achieved by heating and / or applying reduced pressure, according to techniques known to those skilled in the art. Dewatering can be achieved by any technique known to those skilled in the art, such as centrifugation or compression. Preferably, dewatering is achieved by compression, in particular by compression of the magma, for example using a conical screw press fitted into a complementary sleeve allowing only the processing composition to pass between them. Preferably, the partial removal of the processing composition is achieved by dewatering.

[0056] According to an advantageous embodiment, the transformation composition recovered during the elimination of the transformation composition from the magma is reused in the process of transforming expanded polystyrene into magma, in step C.

[0057] Advantageously, the polystyrene magma comprises less than 30% by weight of transformation composition, preferably 15% to 25%, and even better 17% to 20%, relative to the total weight of the magma. According to a particular embodiment of the invention, the magma used and present in the adhesive comprises 17% by weight of transformation composition relative to the total weight of the magma.

[0058] The polystyrene magma comprises predominantly polystyrene and a minor amount of a particular transformation composition. More precisely, the magma comprises at least 70% by weight of polystyrene relative to the total weight of the magma, preferably 75% to 85%, and even better 80% to 83%. The polystyrene is in an amorphous, unexpanded state within the magma.

[0059] The process for preparing the polystyrene magma, and the device for manufacturing it, may be as described in patent FR 2 766 832 and / or in patent application FR 24 04962.

[0060] The transformation composition, used for the preparation of the magma and present in the glue according to the invention, comprises at least one solvent, at least one lubricant and at least one alcohol.

[0061] Various solvents or mixtures of solvents can be used in the transformation composition, such as acetone.

[0062] According to an advantageous embodiment, the transformation composition comprises acetone, alone or in a mixture with one or more other solvents.

[0063] According to a particularly preferred embodiment of the invention, the transformation composition comprises a single solvent, which is preferably acetone.

[0064] The transformation composition comprises 92% to 98% by volume of solvent(s), preferably 94% to 98% by volume, preferably 96% to 98% by volume, and even more preferably 97% to 98% by volume, relative to the volume of the transformation composition. According to a particular embodiment of the invention, the transformation composition comprises 97% by volume of solvent(s).

[0065] According to an advantageous embodiment of the invention, the transformation composition comprises at least 50% by volume of acetone, preferably at least 70% by volume, preferably at least 90% by volume, preferably from 92% to 98.5% by volume, preferably from 94% to 98% by volume, preferably from 96% to 98% by volume, and even more preferably from 97% to 98% by volume, relative to the volume of the transformation composition. According to a particularly advantageous embodiment, the transformation composition comprises 97% by volume of acetone, relative to the volume of the transformation composition.

[0066] At least one lubricant in the transformation composition is preferably a non-greasy lubricant, such as Teflon (or polytetrafluoroethylene or PTFE) or glycerin for example.

[0067] Advantageously, the transformation composition comprises glycerin, alone or in combination with one or more other lubricants.

[0068] According to a particularly preferred embodiment of the invention, the transformation composition comprises a single non-greasy lubricant, which is preferably glycerin.

[0069] Advantageously, the transformation composition comprises 1 to 2% by volume of lubricant(s), preferably 1.5% to 2% by volume, relative to the volume of the transformation composition.

[0070] According to an advantageous embodiment of the invention, the transformation composition comprises 1 to 2% by volume of glycerin, preferably 1.5% to 2% by volume, relative to the volume of the transformation composition. According to a particularly advantageous embodiment, the transformation composition comprises 1.5% by volume of glycerin, relative to the volume of the transformation composition.

[0071] Various alcohols can be used in the processing composition. Advantageously, at least one alcohol in the processing composition is chosen among the aliphatic or cycloaliphatic alcohols, linear or branched, comprising 1 to 15 carbon atoms, and preferably an aliphatic alcohol, linear or branched, comprising 1 to 10 carbon atoms. Preferably, at least one alcohol is a saturated aliphatic or cycloaliphatic alcohol, linear or branched, comprising 1 to 15 carbon atoms, and preferably an aliphatic alcohol, linear or branched, saturated, comprising 1 to 10 carbon atoms. Examples of alcohols that may be used include, in particular, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secbutanol, pentanol, isopentanol, secpentanol, hexanol, cyclohexanol, and mixtures thereof. According to an advantageous embodiment of the invention, at least one solvent is chosen from ethanol, isopropanol and mixtures thereof.According to one particular embodiment of the invention, the transformation composition comprises a single alcohol, namely ethanol. According to another particular embodiment of the invention, the transformation composition comprises a single alcohol, namely isopropanol.

[0072] Advantageously, the transformation composition comprises from 0.5% to 6% by volume of alcohol(s), preferably from 0.5% to 4% by volume, and even better from 1% to 2% by volume, relative to the total volume of the transformation composition. According to a particular embodiment, the transformation composition comprises 1.5% by volume of alcohol(s), relative to the volume of the transformation composition.

[0073] According to an advantageous embodiment of the invention, the transformation composition comprises from 0.5% to 6% by volume of ethanol, isopropanol, or a mixture thereof, preferably from 0.5% to 4% by volume, and even more preferably from 1% to 2% by volume, relative to the volume of the transformation composition. According to a particular embodiment, the transformation composition comprises 1.5% by volume of ethanol, isopropanol, or a mixture thereof, relative to the volume of the transformation composition.

[0074] According to a particular embodiment of the invention, the transformation solution comprises a single solvent, preferably acetone, a single non-greasy lubricant, preferably glycerin and at least one alcohol, preferably ethanol or isopropanol, or a mixture thereof.

[0075] According to a particular embodiment of the invention, the transformation solution comprises a single solvent, preferably acetone, a single lubricant, preferably glycerin and a single alcohol, preferably ethanol.

[0076] According to a particular embodiment of the invention, the transformation solution comprises a single solvent, preferably acetone, a single lubricant, preferably glycerin and a single alcohol, preferably isopropanol.

[0077] In addition to the polystyrene magma, the glue comprises a chlorinated solvent selected from trichloroethylene, tetrachloroethylene (also called perchloroethylene) and their mixture. Tetrachloroethylene is preferred due to its lower toxicity.

[0078] The adhesive comprises from 0.25 kg to 0.40 kg of chlorinated solvent(s) per kg of magma, preferably from 0.28 kg to 0.36 kg. In other words, the mass ratio of chlorinated solvent(s) to magma in the adhesive ranges from 0.25 to 0.4, and preferably from 0.28 to 0.36. The exact content of chlorinated solvent(s) influences the final viscosity of the adhesive and can be determined by those skilled in the art according to the desired final viscosity of the adhesive.

[0079] The adhesive according to the invention is a one-component adhesive that allows bonding of various materials, such as wood, tiles, stone, concrete, ceramics, polyethylene (PE), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), paper, cardboard, or plexiglass, for example. It has the advantage of requiring a relatively short pressure-setting time, typically less than 2 hours.

[0080] The invention also relates to the use of glue to fix together various materials, such as wood, tiles, stone, concrete, ceramics, polyethylene (PE), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), paper, cardboard, or plexiglass, for example.

[0081] The adhesive can be applied to the materials to be bonded using any technique known to those skilled in the art. Then, the surfaces to be bonded (at least one of which is coated with adhesive) are brought into contact, and then pressure is optionally applied.

[0082] The invention also relates to a method for manufacturing an adhesive according to the invention. The method comprises the following steps:

[0083] i) to have a polystyrene magma containing at least 70% by weight of polystyrene, relative to the weight of the magma, said polystyrene being in an amorphous, unexpanded state,

[0084] ii) have a chlorinated solvent selected from trichloroethylene, tetrachloroethylene or a mixture thereof,

[0085] iii) bring the magma into contact with 0.25 kg to 0.40 kg, preferably 0.28 kg to 0.36 kg, of chlorinated solvent per kg of polystyrene magma.

[0086] During steps i) and ii), the magma and the chlorinated solvent(s) are as described above in relation to the glue according to the invention.

[0087] In step iii), the solvent and the polystyrene magma can be brought into contact in a reactor: the chlorinated solvent(s) can be added to the magma or vice versa. Advantageously, the magma and the chlorinated solvent(s) are mixed, for example by mechanical stirring, preferably at a speed less than 700 rpm. Advantageously, this step is carried out at ambient temperature and atmospheric pressure.

[0088] The invention also relates to a container or receptacle comprising the glue according to the invention, or the glue obtained according to the invention. The container or receptacle that may be used is of any type suitable for liquid or paste-like glues, such as syringes, tubes, or bottles, for example. Examples

[0089] Example 1: preparation of an adhesive according to the invention

[0090] For the production of the glue according to the invention, the following were used:

[0091] - expanded polystyrene from packaging for household appliances, reduced to pieces whose largest dimension is less than 20 cm,

[0092] - transformation composition: 96.5% by volume of acetone (99.8% commercially available) by Brenntag), 1.5% by volume of glycerin (99.5%, marketed by Brenntag), and 2% by volume of isopropanol (99.9%, marketed by Brenntag), relative to the total volume of the processing composition, and

[0093] - tetrachloroethylene (100%, marketed by Brenntag).

[0094] First, the polystyrene magma was obtained by spraying 8.57 kg of the transformation composition onto 11.43 kg of expanded polystyrene. After a few minutes, structural collapse was observed. The magma was then dewatered by compressing it and passing the transformation composition through a conical screw press nested within a complementary conical sleeve. The clearance between the screw press and the sleeve was such that only the transformation composition passed through. Thus, after dewatering, 20 kg of polystyrene magma were recovered and then placed in a 60 L polyethylene drum.

[0095] Next, 2.63 L of tetrachloroethylene (corresponding to 0.26 x 20 kg = 5.2 kg) were poured into the drum containing the magma, without stirring.

[0096] After 5 min, the mixture was mechanically agitated (200 rpm for 8 min then 400 rpm for 2 min).

[0097] The resulting adhesive was tested for bonding two polyester and polypropylene panels. 200 g of adhesive per square meter of panel were applied to the surface of each panel using a spatula. After 4 minutes and 30 seconds of film formation and 1 hour and 30 minutes of pressure application, the two polyester and polypropylene panels were firmly bonded together.

[0098] Example 2 outside the scope of the invention

[0099] Here, the following were used:

[0100] - expanded polystyrene from packaging for household appliances, reduced to pieces whose largest dimension is less than 20 cm,

[0101] - Transformation composition: 96.5% by volume of acetone (99.8% commercially available) by Brenntag), 1.5% by volume of glycerin (99.5%, marketed by Brenntag), and 2% by volume of isopropanol (99.9%, marketed by Brenntag), relative to the total volume of the processing composition, and

[0102] - of 1,1,1-trichloroethane (100%, marketed by Brenntag).

[0103] First, the polystyrene magma was obtained by spraying 8.57 kg of the transformation composition onto 11.43 kg of expanded polystyrene. After a few minutes, structural collapse was observed. The magma was then dewatered by compressing it and passing the transformation composition through a conical screw press fitted into a complementary conical sleeve. The clearance between the screw press and the sleeve was such that only the transformation composition passed through. Thus, after dewatering, 20 kg of polystyrene magma were recovered and then placed in a 60 L polyethylene drum.

[0104] Next, 2.63 L of 1,1,1-trichloroethane (corresponding to 0.26 x 20 kg = 5.2 kg) were poured into the drum containing the magma, without stirring.

[0105] After 5 min, the mixture was mechanically agitated (200 rpm for 8 min then 400 rpm for 2 min).

[0106] We observe a dissolution of the polystyrene constituting the magma, with a kinematic viscosity that is too low.

[0107] The resulting composition was applied with a spatula to two polyester and polypropylene panels. However, the volatility of 1,1,1-trichloroethane (greater than that of tetrachloroethylene) prevents the coating from being completed on a surface area (50 cm² in this example). Threads resembling spider silk are observed to appear.

[0108] Applying pressure to the two panels does not result in adhesion or bonding.

Claims

Demands

1. Adhesive comprising: - a polystyrene magma containing at least 70% by weight of polystyrene relative to the weight of the polystyrene magma, said polystyrene being in an amorphous, unexpanded state, and - 0.25 kg to 0.40 kg, preferably 0.28 kg to 0.36 kg, of chlorinated solvent per kg of polystyrene magma, the chlorinated solvent being selected from trichloroethylene, tetrachloroethylene and mixtures thereof.

2. Adhesive according to claim 1, wherein the chlorinated solvent is tetrachloroethylene.

3. Adhesive according to claim 1 or 2, wherein the polystyrene magma comprises a transformation composition.

4. Adhesive according to the preceding claim, wherein the processing composition is present in a content of 15% to 25% by weight, preferably 17% to 20% by weight, relative to the total weight of the polystyrene magma.

5. Adhesive according to claim 3 or 4, wherein the processing composition comprises at least one solvent, at least one lubricant and at least one alcohol.

6. Adhesive according to any one of claims 3 to 5, wherein the processing composition comprises at least one solvent in a content of 92% to 98% by volume, relative to the volume of the processing composition.

7. Glue according to any one of claims 3 to 6, wherein the processing composition comprises a single solvent, which is acetone.

8. Adhesive according to any one of claims 3 to 7, wherein the processing composition comprises at least one lubricant in a content of 1% to 2% by volume, relative to the volume of the processing composition.

9. Adhesive according to any one of claims 3 to 8, wherein the processing composition comprises a single lubricant which is glycerin.

10. Glue according to any one of claims 3 to 9, wherein the processing composition comprises at least one alcohol in a content of 0.5% to 6% by volume, preferably 1% to 2% by volume, relative to the volume of the processing composition.

11. Glue according to any one of claims 3 to 10, wherein the transformation composition comprises an alcohol selected from aliphatic or cycloaliphatic alcohols, linear or branched, comprising 1 to 15 carbon atoms, and preferably an aliphatic alcohol, linear or branched, comprising 1 to 10 carbon atoms.

12. Glue according to the preceding claim, wherein the alcohol is selected from ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol and mixtures thereof, preferably from ethanol, isopropanol and mixtures thereof.

13. A method for manufacturing an adhesive according to any one of the preceding claims comprising the following steps: i) having a polystyrene magma containing at least 70% by weight of polystyrene, relative to the weight of the magma, said polystyrene being in an amorphous, unexpanded state, ii) having a chlorinated solvent selected from trichloroethylene, tetrachloroethylene or a mixture thereof, and iii) bringing the magma into contact with 0.25 kg to 0.40 kg, preferably 0.28 kg to 0.36 kg, of chlorinated solvent per kg of magma.

14. A method according to the preceding claim, wherein in step iii), the chlorinated solvent is mixed with the polystyrene magma.

15. A process according to claim 13 or 14, wherein the polystyrene magma is obtained by contacting expanded polystyrene with a transformation composition comprising at least one solvent, at least one lubricant and at least one alcohol.

16. Container containing the glue according to any one of claims 1 to 12, or obtained according to any one of claims 13 to 15.