Glue obtained from a polystyrene slurry

Abstract

The invention relates to a glue comprising a polystyrene slurry and a chlorinated solvent selected from trichloroethylene, tetrachloroethylene and a mixture thereof. The invention also relates to the method for preparing the glue according to the invention. The invention also relates to a bottle containing the glue according to the invention.

Description

Description Title of the invention: Glue obtained from a polystyrene magma Technical Field

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

[0002] In general, it is desirable to recover value from various types of waste, whether industrial or not. Ideally, this recovery should be economical, energy-efficient, and easy to implement.

[0003] The use of expanded polystyrene is widespread, generating large quantities of expanded polystyrene waste that is difficult to reuse, particularly for food applications. To date, two different techniques have been proposed for treating expanded polystyrene waste: destruction or recycling.

[0004] Expanded polystyrene is typically destroyed by incineration. This solution is neither economical nor environmentally friendly. Recycling is a preferred alternative.

[0005] Expanded polystyrene (EPS) recycling can be either mechanical or chemical. Mechanical recycling involves crushing the EPS, then compacting it, and finally generating EPS granules. A major drawback of mechanical recycling is that it requires prior cleaning of the EPS to be recycled. Furthermore, mechanical recycling requires high pressure and temperature to soften the EPS, and is therefore energy-intensive. It should also be noted that EPS residue can easily be dispersed during the recycling process. Mechanical recycling. Furthermore, mechanical recycling does not allow for the subsequent use of recovered polystyrene for food contact, but only for non-food areas such as insulation or household appliance packaging, for example.

[0006] Chemical recycling generally involves depolymerizing polystyrene to recover styrene. The most common method for chemically recycling expanded polystyrene is thermal depolymerization, or thermolysis, using conventional heat or microwaves. This method thermally cracks the polymer and breaks its chains to obtain monomers (benzene, toluene, styrene). The yield of aromatic compounds from polystyrene is high. The resulting styrene monomer can then be repolymerized to obtain polystyrene. This method makes it possible to consider reusing polystyrene for food contact applications. However, thermal depolymerization is energy-intensive and very expensive.

[0007] Document EP 0 321 731 describes a process for treating plastic waste, particularly polystyrene-based waste, comprising solubilizing this waste in a solvent or mixture of solvents, and separating the resulting solution from the insoluble residues. The solution can then be used as an adhesive.

[0008] An alternative method was described in French patent FR 2 766 832, which concerns a process for transforming expanded polymers, particularly expanded polystyrene, into a flexible, paste-like mass resulting from the collapse of the expanded polystyrene's internal structure, without any chemical modification of the polystyrene itself. The described process involves treating the expanded polystyrene with a transformation composition comprising a solvent, a non-greasy lubricant, and an alcohol. Various uses for the resulting mass are envisaged, such as the manufacture of various articles, insulation, sealants, or adhesives, although no explanation is provided for their implementation.

[0009] Similarly, there is a need to improve the recycling and recovery of semi-expanded, extruded or crystal polystyrene. Description of the invention

[0010] In this context, the Applicant became interested in the valorization of polystyrene waste, and in particular expanded polystyrene, for the manufacture of an adhesive. More specifically, the invention relates to an adhesive comprising:

[0011] - 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

[0012] - 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.

[0013] The Applicant was surprised to find that a precise quantity of a particular solvent, mixed with a polystyrene magma, made 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.

[0014] In the context of the invention, the glue may have one or more of the following characteristics, or a combination thereof:

[0015] - the chlorinated solvent is tetrachloroethylene;

[0016] - the polystyrene magma comprises a transformation composition;

[0017] - the transformation composition is present in a content ranging from 15% to 25% by weight, preferably from 17% to 20% by weight, relative to the total weight of the polystyrene magma;

[0018] - the transformation composition includes at least one solvent, at least one lubricant and at least one alcohol;

[0019] - the transformation composition includes at least one solvent in a content ranging from 92% to 98% by volume, relative to the volume of the transformation composition;

[0020] - the transformation composition includes a single solvent, which is acetone;

[0021] - the transformation composition includes at least one lubricant in a content ranging from 1% to 2% by volume, relative to the volume of the transformation composition;

[0022] - the transformation composition includes a single lubricant which is glycerin;

[0023] - the transformation composition includes at least one alcohol in a content ranging from 0.5% to 6% by volume, preferably 1% to 2% by volume, relative to the volume of the transformation composition;

[0024] - 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; and

[0025] - the alcohol is chosen from ethanol, propanol, isopropanol, butanol, isobutanol, secbutanol and mixtures thereof, preferably from ethanol, isopropanol and mixtures thereof.

[0026] The invention also relates to a method for preparing an adhesive comprising the following steps:

[0027] (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,

[0028] ii) have a chlorinated solvent selected from trichloroethylene, tetrachloroethylene or a mixture thereof, and

[0029] 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.

[0030] In the context of the invention, the glue preparation process may have one or more of the following characteristics:

[0031] - in step iii), the chlorinated solvent is mixed with the polystyrene magma; and

[0032] - Polystyrene magma is obtained by bringing polystyrene (for example expanded polystyrene) into contact with a transformation composition comprising at least one solvent, at least one lubricant and at least one alcohol.

[0033] 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.

[0034] 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

[0035] The invention relates to the valorization of polystyrene waste, particularly expanded polystyrene, for the manufacture of an adhesive, via the transformation of polystyrene, and for example expanded polystyrene, into a polystyrene magma. More specifically, the adhesive comprises a polystyrene magma and a particular chlorinated solvent.

[0036] In the context of this 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 polystyrene (expanded, semi-expanded, extruded, crystalline, etc.), and preferably expanded polystyrene, with a transformation composition, as detailed below, resulting in a collapse of the internal structure of the expanded polystyrene or a reorganization of the non-expanded polystyrene, without chemical modification of the polymer. Thus, polystyrene magma (or simply magma in the following description) comprises polystyrene in a non-expanded and amorphous form.

[0037] In the context of the invention, the polystyrene magma is prepared according to the following successive steps:

[0038] A) Have polystyrene part(s) (for example, expanded polystyrene) available to treat,

[0039] B) possibly remove impurities from the polystyrene piece(s) (for example, expanded polystyrene) and / or possibly crush or grind the polystyrene piece(s) (for example, expanded polystyrene), in order to obtain polystyrene fragments (for example, expanded polystyrene) whose largest dimension is less than 30 cm, preferably less than 20 cm, and even better less than 10 cm,

[0040] C) apply a transformation composition to the polystyrene parts and / or fragments (e.g., expanded polystyrene) to be treated,

[0041] D) possibly filter the resulting magma,

[0042] E) possibly eliminate, partially or totally, the transformation composition of the magma obtained, and

[0043] F) Optionally add the transformation composition.

[0044] In the context of the invention, the magma is obtained from any type of polystyrene, and in particular from expanded and / or semi-expanded and / or extruded and / or crystalline polystyrene. For the sake of simplicity, the entire description refers to expanded polystyrene as it is particularly preferred (because it allows for the recovery of many waste materials), but it is understood that everything described in connection with expanded polystyrene could apply equally to semi-expanded, extruded, crystalline polystyrene or a mixture thereof, unless otherwise specified.

[0045] According to a preferred embodiment 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.

[0046] Expanded polystyrene can come from various sources, such as insulation panels, appliance packaging, or other packaging materials. food-grade, for example. It is understood that, within the scope of the invention, the origin of the polystyrene (expanded or otherwise) is not limiting, and that one or more different sources of polystyrene (expanded, non-expanded, or mixtures thereof) may be used to manufacture the polystyrene magma and then the adhesive according to the invention. Advantageously, it is not necessary to wash the polystyrene (for example, expanded) prior to its use: indeed, it is not necessary for the polystyrene (for example, expanded polystyrene) to be free of impurities for the manufacture of the polystyrene magma that will be used in the adhesive according to the invention. It is nevertheless possible to remove impurities, either when the polystyrene is still in its expanded form, for example, or in step D when the polystyrene is in its amorphous form, or both.

[0047] Advantageously in step B), the polystyrene piece(s) (e.g., expanded polystyrene) are crushed to obtain polystyrene fragments (e.g., expanded polystyrene) 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 polystyrene fragments (e.g., expanded polystyrene) are not in granule or pellet form, and that their largest dimension is advantageously greater than 3 cm. It is understood that not all the fragments are necessarily the same size, and that a typical size distribution is obtained.Although not mandatory, this step facilitates the collapse or dispersion of the polystyrene in step C (i.e. the transformation of the polystyrene in its expanded form to an amorphous non-expanded form, or its reorganization in the case of the use of non-expanded polystyrene), and in particular allows to limit the amount of transformation composition required while maintaining a good rate of collapse.

[0048] 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.

[0049] The application of the transformation composition can be carried out in various ways, such as, for example, by immersing the parts and / or Polystyrene fragments (e.g., expanded polystyrene) are incorporated into the processing composition, or the processing composition is sprayed onto pieces and / or fragments of polystyrene (e.g., expanded polystyrene). Generally, spraying the processing composition is preferred because the resulting collapse requires smaller quantities of composition, thus reducing costs and potentially eliminating the need for a subsequent step of partially removing the processing composition from the resulting molten mass. Furthermore, the treatment is faster by spraying than by immersion. Immersion in the processing composition may be preferred when small quantities of polystyrene (e.g., expanded polystyrene) are involved.

[0050] When spraying the processing composition onto the polystyrene parts and / or fragments (e.g., expanded polystyrene), the amount of processing composition sprayed is determined based on the amount of polystyrene (e.g., expanded polystyrene) to be treated. Advantageously, 0.6 kg to 0.9 kg of processing composition per kg of polystyrene (e.g., expanded polystyrene) to be treated is used, and preferably 0.7 kg to 0.8 kg of processing composition per kg of polystyrene (e.g., expanded polystyrene) to be treated. In one particular embodiment, 0.75 kg of processing composition per kg of polystyrene (e.g., expanded polystyrene) is applied. The resulting mass of the resulting mixture then corresponds to the sum of the mass of polystyrene (e.g., expanded polystyrene) to be treated and the mass of the sprayed processing composition.

[0051] When immersing the polystyrene (e.g., expanded polystyrene) to be treated (i.e., the piece(s) and / or fragment(s) of polystyrene to be treated), a sufficient quantity is used to ensure that all of the polystyrene (e.g., expanded polystyrene) to be treated is completely immersed in the processing solution. The exact quantities depend on the container and the amount of polystyrene (e.g., expanded polystyrene) to be treated and can be easily determined by a person skilled in the art. Again, the The mass of magma obtained then corresponds to the sum of the mass of polystyrene to be treated and the mass of the transformation composition in which the polystyrene (for example expanded polystyrene) was immersed.

[0052] 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 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 molten mass is not sticky and could not be used as an adhesive.

[0053] 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 a person 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.

[0054] Advantageously, the magma is obtained at ambient temperature and atmospheric pressure.

[0055] 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 glue to be made, so that it does not dry out. Indeed, by completely removing the transformation composition from the magma, it becomes solid and is no longer easily handled.

[0056] 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 polystyrene (for example, expanded polystyrene) into magma, and is not greater than the quantity of composition of transformation that may be present in magma for the manufacture of glue, as detailed in this description.

[0057] According to a second preferred embodiment, the transformation composition is partially eliminated. This makes it possible to reduce the transformation composition content in the magma, thereby enabling the subsequent production of the glue.

[0058] Although not preferred, it is nevertheless possible to completely remove the transformation composition from the magma. Once the transformation composition is entirely 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, thus regaining 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, the solid can be broken into pieces and / or crushed.

[0059] The partial or total removal of the processing composition can be achieved by various techniques, such as evaporation or dewatering. Evaporation can be carried out by heating and / or applying reduced pressure, using techniques known to those skilled in the art. Dewatering can be carried out using 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 through which only the processing composition passes. Preferably, the partial removal of the processing composition is achieved by dewatering.

[0060] 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 polystyrene (for example expanded polystyrene) into magma, in step C.

[0061] 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.

[0062] The polystyrene magma consists primarily of polystyrene and a minor amount of a specific transformation composition. More precisely, the magma comprises at least 70% polystyrene by weight relative to the total magma weight, preferably 75% to 85%, and even better 80% to 83%. The polystyrene is in an amorphous, unexpanded state within the magma.

[0063] The process for preparing the polystyrene magma, and the device for manufacturing it, can be as described in patent FR 2 766 832 and / or in patent application FR 24 04962.

[0064] 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.

[0065] Various solvents or solvent mixtures can be used in the transformation composition, such as acetone.

[0066] According to an advantageous embodiment, the transformation composition comprises acetone, alone or in a mixture with one or more other solvents.

[0067] According to a particularly preferred embodiment of the invention, the transformation composition comprises a single solvent, which is preferably acetone.

[0068] 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 better 97% to 98% by volume, relative to the volume of the transformation composition. According to one embodiment particular to the invention, the transformation composition comprises 97% by volume of solvent(s).

[0069] 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.

[0070] At least one lubricant in the processing composition is preferably a non-greasy lubricant, such as Teflon (or polytetrafluoroethylene or PTFE) or glycerin, for example.

[0071] Advantageously, the transformation composition includes glycerin, alone or in combination with one or more other lubricants.

[0072] According to a particularly preferred embodiment of the invention, the transformation composition comprises a single non-greasy lubricant, which is preferably glycerin.

[0073] 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.

[0074] 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.

[0075] Various alcohols can be used in the processing composition. Advantageously, at least one alcohol in the processing composition is chosen 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. 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.

[0076] Advantageously, the processing 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 processing composition. According to a particular embodiment, the processing composition comprises 1.5% by volume of alcohol(s), relative to the volume of the processing composition.

[0077] According to an advantageous embodiment of the invention, the transformation composition comprises from 0.5% to 6% by volume of ethanol, isopropanol or their mixture, preferably from 0.5% to 4% by volume, and even better 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 their mixture, relative to the volume of the transformation composition.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] Besides the polystyrene mass, the adhesive includes a chlorinated solvent chosen from trichloroethylene, tetrachloroethylene (also called perchloroethylene), and mixtures thereof. Tetrachloroethylene is preferred due to its lower toxicity.

[0082] The adhesive contains 0.25 kg to 0.40 kg of chlorinated solvent(s) per kg of magma, preferably 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) affects the final viscosity of the adhesive and can be determined by a person skilled in the art based on the desired final viscosity.

[0083] The adhesive according to the invention is a single-component adhesive that can bond 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 curing time, typically less than 2 hours.

[0084] 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.

[0085] The adhesive can be applied to the materials to be bonded using any technique known to a person skilled in the art. Then, the surfaces to be bonded (at least one of which must be coated with adhesive) are brought into contact, and pressure may be applied if necessary.

[0086] The invention also relates to a method for manufacturing an adhesive according to the invention. The method comprises the following steps:

[0087] (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,

[0088] ii) have a chlorinated solvent available, selected from trichloroethylene, tetrachloroethylene or a mixture thereof,

[0089] 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.

[0090] 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.

[0091] 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 below 700 rpm. Advantageously, this step is carried out at ambient temperature and atmospheric pressure.

[0092] The invention also relates to a container or receptacle comprising the adhesive according to the invention, or the adhesive obtained according to the invention. The container or receptacle that may be used is of any type suitable for liquid or paste adhesives, such as syringes, tubes, or bottles, for example.

[0093] Examples

[0094] Example 1: Preparation of an adhesive according to the invention

[0095] The following materials were used to produce the glue according to the invention:

[0096] - expanded polystyrene from packaging for household appliances, reduced to pieces whose largest dimension is less than 20 cm,

[0097] - transformation composition: 96.5% by volume of acetone (99.8% marketed 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 transformation composition, and

[0098] - tetrachloroethylene (100%, marketed by Brenntag).

[0099] 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 inside a complementary conical sleeve. The gap between the screw press and the sleeve was such that only the transformation composition passed through. Following dewatering, 20 kg of polystyrene magma were recovered and then placed in a 60 L polyethylene drum.

[0100] 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.

[0101] After 5 minutes, the mixture was mechanically stirred (200 rpm for 8 minutes then 400 rpm for 2 minutes).

[0102] The resulting adhesive was tested for bonding two polyester and polypropylene panels. 200g of adhesive / m² 2 The film was applied to the surface of each panel using a spatula. After 4 minutes and 30 seconds of film application and 1 hour and 30 minutes of pressure curing, the two polyester and polypropylene panels were securely bonded together.

[0103] Example 2 outside of invention

[0104] The following were used here:

[0105] - expanded polystyrene from packaging for household appliances, reduced to pieces whose largest dimension is less than 20 cm,

[0106] - transformation composition: 96.5% by volume of acetone (99.8% marketed 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 transformation composition, and

[0107] - 1,1,1-trichloroethane (100%, marketed by Brenntag).

[0108] 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 inside a complementary conical sleeve. The gap between the screw press and the sleeve was such that only the transformation composition passed through. Following dewatering, 20 kg of polystyrene magma were recovered and then placed in a 60 L polyethylene drum.

[0109] 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.

[0110] After 5 minutes, the mixture was mechanically stirred (200 rpm for 8 minutes then 400 rpm for 2 minutes).

[0111] We observe a dissolution of the polystyrene constituting the magma, with a kinematic viscosity that is too low.

[0112] 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) prevented the coating from being completed on a surface area of ​​50 cm². 2 (in this example). We observe the appearance of threads similar in appearance to spider web threads.

[0113] 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 chosen from trichloroethylene, tetrachloroethylene and their mixture.

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, secbutanol 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 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 the glue obtained according to any one of claims 13 to 15.