DESCRIPTION

SCOPE OF APPLICATION

The present invention relates to a process for the recovery of synthetic fabrics, after their use and their wear, in order to be able to recycle them and reuse them again in the manufacture of various articles, such as awnings, clothing, interior and exterior furniture.

In particular, the invention refers to a process for the recovery and recycling of synthetic, natural and mixed fibers, which allows to effectively remove the additive chemical compounds present in the fibers, so that they can advantageously be recycled, and used again in the textile industry as if they were a virgin fabric.

BACKGROUND ART

The acrylic and polyester fibers (PES) are known to be among the most widely used synthetic fibers, especially in the production of clothing, sports fabrics, awnings, parasols, etc. They are distinguished by their high thermal insulation, the unshrinkability during washing and the resistance to light or other atmospheric agents.

The acrylic or polyester-based fabric has proven particularly suitable for the production of outdoor curtains, as it has good resistance to external atmospheric agents, such as solar irradiation, wind, rain etc. This is also a fabric that can be deeply dyed, that is, impregnated in colour up to the innermost fibers for fabric decoration.

Being constantly in contact with external weather agents, awnings are subject to wear and corrosion with a severe deterioration of their performance in terms of aesthetics and shading. Consequently, to ensure their durability over time, the acrylic fibers that make up the awnings are added with specific chemical compounds, which reinforce their mechanical resistance, water repellency and la stain resistance.

We can mention, for example, the following categories of chemical additives that are commonly used in the treatment of synthetic fibers, acrylic or polyester-based, in the specific sector of awnings and parasol fabrics:

1) Melamine resins obtained by polycondensation of formaldehyde with melamine, used in liquid form to impregnate the acrylic fabric of the curtains in order to make it thermoset.

2) Ce fluorocarbon resins used to impart water-repellency and oil-repellency to acrylic fabrics, so that awnings are poorly wetable by water and are protected from the possible adhesion of stains, pollutants on their surface;

3) Polyurethane resins with which the acrylic fabrics are impregnated or coated, in order to improve their aesthetic appearance and increase their rigidity and resilience.

Water repellency is a very important feature as it allows water to drain away during rain, thus preventing water, which is often laden with pollutants, from penetrating the acrylic fabric, ruining it and contaminating it with harmful substances. The water repellency treatment by means of Ce fluorocarbon resins is also useful to counteract the onset of moulds that could form in the case of stagnant water.

Thanks to the treatment with the chemical additives listed above, the acrylic fiber-based fabrics used for awnings and parasols can also be kept in good condition for many years.

Also known in the sector of acrylic and polyester fibers are some techniques aimed at recovering processing waste deriving from the manufacture of awnings. The processing waste (cuttings, weft waste, etc.) are first subjected to the “fraying” technique, so as to reduce them into thin filaments that join together to form the so-called “flakes” of acrylic fabric . These flakes are then subjected to washing with appropriate detergents so as to achieve a cleaning thereof.

After the washing phase, a variable percentage of these acrylic fiber flakes coming from the processing waste is mixed with other preselected natural and synthetic fibers that are used for the first time (virgin material). In this way, good quality fabrics can be obtained that can still be used for the production of awnings, as certain characteristics such as colour fastness to UV rays, stain-resistant and mould-resistant behaviour are preserved.

The process described above allows to reduce the consumption of raw materials, such as monomers and solvents, commonly used in the manufacture of awnings and/or parasols. However, the partially recycled acrylic fibers obtained with the method described above are not suitable for use in the manufacture of many textile articles, as the portion of recycled filaments has not been purified from the presence of the various resins previously added to make the acrylic fabrics suitable for the manufacture of awnings, parasols, etc. Being impregnated with the melamine, fluorocarbon and polyurethane resins mentioned above, these partially recycled synthetic fibers cannot be used, for example, in the manufacture of fabrics intended for the clothing sector and in many other sectors.

In light of the aforementioned drawbacks, the need is felt to make available to the textile sector an innovative and effective process to remove the aforementioned chemical additives (melamine, fluorocarbon and polyurethane resins) from a worn fabric based on synthetic, natural and mixed fibers.

Therefore, a first object of the process according to the present invention is to achieve a thrust removal, generally higher than 95-99% by weight, of the chemical additives present in worn fabrics based on acrylic fibers.

A second object of the process according to the present invention is the possibility of not having to dispose of worn fabrics, such as awnings, parasols, tablecloths and technical textile articles, in landfills. This is clearly a huge advantage from an environmental point of view.

A further object of the process according to the invention is to be able to fully reuse the purified textile fibers in the manner reported below for the production of new articles in the textile field.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

DISCLOSURE OF THE INVENTION

The present invention is expressed and characterized in the independent claims, while the dependent claims set forth other preferred and non-essential features of the present invention, or variants of the main solution idea.

An object of the present invention is therefore constituted by a process for the removal of chemical additives from fabrics based on synthetic, natural or mixed fibers, the process comprising the following steps: a) treating portions of said fabrics inside an acid hydrolysis bath having 1 <pH <5 and a temperature between 60 °C and 140 °C in the presence of the following compounds: anionic and/or non-ionic surfactants; pH buffering agents; optionally one or more wetting compounds; b) treating the fabrics obtained from step a) inside an alkaline hydrolysis bath having 9 <pH <13 and a temperature between 60 °C and 140 °C in the presence of the following compounds: cationic and/or non-ionic surfactants; pH buffering agents; optionally one or more wetting compounds; c) subjecting the fabrics obtained from step b) to a neutralization treatment by means of one or more organic acids.

The Applicant has realized an effective and simple process, capable of removing with excellent yields some of the polymeric resins that are commonly added to the fabrics made of synthetic, natural or mixed fibers, to make them suitable for the sector of application for which they are intended.

As explained in the section on the state of the art, awnings and parasols are subject to wear and corrosion with severe deterioration of their aesthetic and shading performance. In order to guarantee their durability over time, the acrylic fibers that make them up are added with specific chemical compounds, which reinforce their mechanical resistance, water repellency and la stain resistance. The innovative process described in this patent application is aimed at removing these chemical additives, so that the fabrics can be reused again once the chemical additives have been removed.

The operating conditions in accordance with the process of the present invention can be adjusted and adapted based on the type of fibers of which the fabric is composed, as well as based on the type of finishing to which the fabrics have been subjected. As a result, it is very effective in removing various chemicals/additives, so that the regenerated fabrics can be recycled and used again in the most varied applications.

The chemical additives that the process according to the invention aims to remove mainly comprise melamine resins, fluorocarbon resins and polyurethane resins. As explained above, these resins give the awnings and the parasols mechanical resistance, hydro- and oil repellency, rigidity and resilience properties.

The process in accordance with the invention can be applied to any type of synthetic, natural or mixed fibers, however it has proved particularly effective in removing additives from acrylic- and/or polyester-based fibers.

The removal of the aforementioned additives from the worn fabrics based on acrylic or polyester is carried out by means of a process that provides for a double hydrolysis treatment, first in an acidic environment and subsequently in an alkaline environment. During this double hydrolysis treatment, the use of specific surfactants allows the chemical additives to be extracted from the textile fibers, provided that it is operated under the appropriate operating conditions that are the subject-mater of the present invention.

The worn curtains and/or parasols from which the additive resins are to be removed are advantageously cut into small portions before they are subjected to the process of the present invention. In order to make the double hydrolysis treatment as effective as possible, it is preferable, but not indispensable, to perform a mechanical pre-treatment of the worn fabrics before subjecting them to the acid hydrolysis step a) defined above.

Through this mechanical pre-treatment, the worn fabric is frayed in the form of filaments which aggregate into flakes. These filament flakes have been shown to be suitable for maximizing the sequestering action carried out by the surfactants, and the wetting action of some compounds used in the acid and alkaline hydrolysis treatments.

Finally, once the double hydrolysis treatment is ended, the fabrics are subjected to neutralization (step c), using appropriate organic acids in order to bring the pH back to neutral conditions.

The realization of the process for the removal of chemical additives from synthetic, natural and/or mixed fibers in accordance with the present invention allows to obtain multiple advantages in the sector related to the manufacture of awnings and parasols.

The main advantage is certainly the one deriving from the thrust removal, up to 95-99% by weight, of the chemical additives present in the fabrics to be treated. This high level of purification allows to be able to recycle and thus reuse the fibers entirely for the production of new textile articles in the most varied sectors, such as clothing, furniture, awnings and parasols.

A second very important advantage concerns the environmental aspect, since thanks to the implementation of the process according to the invention it is no longer necessary to send the worn fabrics to landfill, but it is possible to fully recycle the acrylic- or polyester-based fibers of which they are made up.

Furthermore, the process in accordance with the invention was also effective with regard to the removal of acrylic-based binders, pigmented thermoplastic or thermosetting polymers on textile articles, non-woven fabric-based para-textiles in polyester fiber.

DETAILED DESCRIPTION OF THE INVENTION

The process for the removal of chemical additives from fabrics worn in accordance with the invention will now be described in detail with reference to the attached Figure 1, which should be considered only by way of non-limiting example of the object of the present invention.

Figure 1 schematically illustrates a sequence of steps to which the worn fabrics are subjected in order to effectively remove the chemical compounds present therein.

The worn fabrics depicted in Fig. 1 are awnings constituted by acrylic fibers, which are sent through a belt conveyor 1 to a mechanical treatment equipment 2, which subjects them to a “fraying” technique. This mechanical pretreatment is an optional step of the process of the invention, which may also be omitted. However, the fraying of the fabric in the form of long filaments which aggregate into flakes improves the yields of the process as it maximises the sequestering action carried out by the surfactants and the action of the wetting compounds used in the subsequent steps of acid and alkaline hydrolysis.

The mechanical treatment equipment 2 may for example be a carding machine, from which flakes of acrylic filaments are discharged. Subsequently, these flakes are transported by means of the belt 3 towards the upper part of an autoclave 4, inside which they will be subjected to the acid hydrolysis treatment (step a) in accordance with the present invention.

The autoclave 4 receives the flakes of acrylic filaments coming from the belt 3 and at the same time, its upper portion is fed through the line 5 with a liquid mixture comprising a suitable non-ionic surfactant and a wetting agent. A mixture comprising water and one or more pH buffering agents is instead inserted into the autoclave 4 through the feed line 6.

Acids, preferably a mixture of phosphonic acids and sulphuric acid, are used as pH buffering agents.

Acid hydrolysis reactions therefore take place within the autoclave 4 between the surfactant and the polymeric resins (additives) present in the filaments of acrylic fibers, which reactions have the effect of removing the polymeric resins from the textile fibers. The operating conditions that are set inside the autoclave 4 during step a) of acid hydrolysis are described below: the pH is maintained in a range between 1 and 5, preferably between 2 and 4; the temperature is maintained in the range between 60° and 140 °C, preferably between 80° and 110 °C, depending on the type of textile fibers being treated.

According to a preferred embodiment of the invention, wetting compounds may optionally be fed into the autoclave 4 during the acid hydrolysis step a). These wetting compounds are selected from ethoxylated alcohols, such as propan-2-ol, 2- methylpropan-l-ol, etc.

As regards the anionic and/or non-ionic surfactants employed in step a) of acid hydrolysis, they are preferably selected from ethoxylated alcohols, propoxylated alcohols having from Cs to CM carbon atoms.

In addition to the liquids mentioned above (surfactants, buffering agents, wetting compounds) the autoclave 4 obviously contains water in a suitable amount. The weight ratio between the solid, i.e. the acrylic filament flakes to be treated, and the liquid phase present inside the autoclave is generally comprised between 0.05 and 0.35, preferably between 0.08 and 0.20. The residence time of the acrylic filament flakes inside the autoclave 4 during phase a) is comprised between 20 minutes and 80 minutes, preferably between 35 and 65 minutes. At the end of this period of time, the autoclave 4 is emptied of the treatment liquid (surfactants, buffering agents, wetting compounds, water) through the discharge line 7, while the solid component (fiber flakes) is deposited on the bottom of the autoclave 4.

Subsequently, the acrylic filament flakes are subjected to the alkaline hydrolysis treatment (step b) in accordance with the invention.

Therefore, a liquid mixture comprising a cationic surfactant and a wetting agent is fed to the autoclave 4 through the line 5, while a mixture of water and caustic soda (pH buffer) is inserted into the autoclave 4 through the feed line 6.

Alkaline hydrolysis reactions therefore take place inside the autoclave 4 between the cationic surfactant and the polymeric resins (additives) present in the filaments of acrylic fibers, which reactions have the effect of removing the polymeric resins from the textile fibers. The operating conditions that are set inside the autoclave 4 during step b) of alkaline hydrolysis are described below: the pH is maintained in a range from 9 to 14, preferably from 10 to 12; the temperature is maintained in the range from 60° to 140 °C, preferably from 80° to 110 °C.

Also in this step, wetting compounds selected from ethoxylated alcohols, such as for example propan-2-ol, 2-methylpropan-l-ol, can be fed into the autoclave 4 during the alkaline hydrolysis step b).

As regards the cationic and/or non-ionic surfactants employed in step b) of alkaline hydrolysis, they are preferably selected from the following group of compounds: ethoxylated and/or propoxylated alcohols having from Cs to C14 carbon atoms, quatemized ethoxylated amines.

In addition to the liquids mentioned above (surfactants, buffering agents, wetting compounds) the autoclave 4 obviously contains water in a suitable amount. The weight ratio between the solid, i.e. the acrylic filament flakes to be treated, and the liquid phase present inside the autoclave during phase b) is generally comprised between 0.05 and 0.35, preferably between 0.08 and 0.20.

The residence time of the acrylic filament flakes inside the autoclave 4 during phase b) is comprised between 20 minutes and 80 minutes, preferably between 35 and 65 minutes. At the end of this period of time, the autoclave 4 is emptied of the treatment liquid (surfactants, buffering agents, wetting compounds, water) through the discharge line 7, while the solid component (fiber flakes) is deposited on the bottom of the autoclave 4.

After the double hydrolysis treatment, the acrylic filament flakes are discharged from the autoclave 4 through the discharge line 8 and are sent to a neutralization treatment 9, as they are soaked with caustic soda. A liquid stream comprising one or more organic acids, preferably acetic acid and formic acid, is fed through the line 10 to the neutralization treatment 9: in this way the alkaline buffering agents are removed, so that the pH of the acrylic fibers is brought back to the desired neutral conditions.

After a residence time in the range between 5 and 30 minutes, the waste liquid coming from the neutralization treatment 9 is discharged through the line 11, while the purified acrylic fiber flakes are extracted from the neutralizer by means of the belt conveyor 12. Finally, downstream of the neutralization treatment, the acrylic fibers now free of the aforementioned chemical additives (melamine resins, fluorocarbons, polyurethanes, etc.) are subjected to a washing phase with water.

The present invention is not limited to the particular embodiments previously described and illustrated in the accompanying drawings, but modifications can be made to it in detail, within the reach of the person skilled in the art, without thereby departing from the scope of the invention itself, as defined in the appended claims.

Further advantages and characteristics of the present invention will become apparent from the following implementation examples, which are to be understood in a descriptive sense and not as limiting the scope of the appended claims.

EXAMPLES

Example 1 (awnings — acrylic fibers)

Worn awnings based on acrylic fibers are treated by means of the process claimed in the present patent application. The chemical additives that are wished to be removed are as follows: fluorocarbon resin Ce (SOFTGARD C6/BO); melamine formayldehyde resin (SOFTNET MMA ECO/2); polyurethane resin (SOFTPUR PET 50).

The awnings are subjected to a mechanical treatment in order to fray them (fraying technique) in the form of filaments which aggregate into flakes. Subsequently, the acrylic filament flakes are subjected to the acid hydrolysis step a) inside an autoclave.

Step a) - Acid hydrolysis

Table 1 indicates the compounds used to remove the chemical additives from the acrylic fiber flakes and the respective concentration used inside the autoclave.

TABLE 1

SOFTWET IP97 is a mixture of propan-2-ol and 2-methylpropan-l-ol;

DETERGENT B10P is a mixture of non-ionic and anionic surfactants (mixture of CS-CM ethoxylated alcohols and Cs-Cu propoxylated alcohols)

SEQUESTER EMG/SB is a mixture of phosphonic acids.

The operating conditions set inside the autoclave are indicated in Table 2.

TABLE 2 Acid hydrolysis reactions take place inside the autoclave between the surfactant and the chemical additives present in the filaments of acrylic fibers, which reactions have the effect of removing the additives mentioned above.

After a residence time of 50 minutes, the autoclave is emptied of the treatment liquid (surfactants, buffering agents, wetting compounds, water), while the solid component (fiber flakes) is deposited on the bottom of the autoclave.

Subsequently, the acrylic filament flakes are subjected to the alkaline hydrolysis treatment (step b) in accordance with the invention.

Step b) - Alkaline hydrolysis

Table 3 indicates the compounds used to remove the chemical additives from the acrylic fiber flakes and the respective concentration used inside the autoclave.

TABLE 3

SOFTWET IP97 is a mixture of propan-2-ol and 2-methylpropan-l-ol.

SOFTCLEANER T NEW is a cationic surfactant, preparation based on fatty amine ethoxylate and glycerin. Caustic soda is used as buffering agent.

The operating conditions set inside the autoclave are indicated in Table 4.

TABLE 4 After a residence time of 50 minutes, the autoclave is emptied of the treatment liquid (surfactants, buffering agents, wetting compounds, water), while the solid component (fiber flakes) is deposited on the bottom of the autoclave.

After the double hydrolysis treatment, the acrylic filament flakes are subjected to a neutralization treatment to remove the caustic soda. A mixture of acetic acid and formic acid is used to bring the pH of the acrylic fibers back to neutral.

Finally, downstream of the neutralization treatment, the acrylic fibers are subjected to a washing phase with water.

The following Table 5 shows the concentrations of the chemical additives present in the worn fabrics, respectively upstream and downstream of the double hydrolysis treatment in accordance with the invention.

TABLE 5

As can be inferred from the data present in Table 5, the process of the present invention allows to obtain a very effective removal, of the order of 99.5% by weight, of the chemical additives originally present in the worn awnings.

Example 2 (Fabrics for nautical furniture - acrylic fibers)

Worn parasols based on acrylic fibers are treated by means of the process claimed in this patent application.

The chemical additives that are wished to be removed are as follows: fluorocarbon resin Ce (SOFTGARD C6/BO); melamine formayldehyde resin (SOFTNET MMA ECO/2); polyurethane resin (SOFTPUR PET 50). The parasols are first subjected to a mechanical treatment in order to fray them in the form of filaments which aggregate into flakes. Subsequently, the acrylic filament flakes are subjected to the acid hydrolysis step a) inside an autoclave.

Step a) - Acid hydrolysis

Table 6 indicates the compounds used to remove the chemical additives from the acrylic fiber flakes and the respective concentration used inside the autoclave.

TABLE 6

SOFTWET IP97 is a mixture of propan-2-ol and 2-methylpropan-l-ol;

DETERGENT B10P is a mixture of non-ionic and anionic surfactants (mixture of Cs-Ci4 ethoxylated alcohols and Cs-Cu propoxylated alcohols)

SEQUESTER EMG/SB is a mixture of phosphonic acids.

The operating conditions set inside the autoclave are indicated in Table 7.

TABLE 7

After a residence time of 45 minutes, the autoclave is emptied of the treatment liquid (surfactants, buffering agents, wetting compounds, water), while the solid component (fiber flakes) is deposited on the bottom of the autoclave.

Subsequently, the acrylic filament flakes are subjected to the alkaline hydrolysis treatment (step b) in accordance with the invention. Step b) - Alkaline hydrolysis

Table 8 indicates the compounds used to remove the chemical additives from the acrylic fiber flakes and the respective concentration used inside the autoclave.

TABLE 8

SOFTWET IP97 is a mixture of propan-2-ol and 2-methylpropan-l-ol.

SOFTCLEANER T NEW is a cationic surfactant, preparation based on fatty amine ethoxylate and glycerin. Caustic soda is used as buffering agent.

The operating conditions set inside the autoclave are indicated in Table 9.

TABLE 9

After a residence time of 40 minutes, the autoclave is emptied of the treatment liquid (surfactants, buffering agents, wetting compounds, water), while the solid component (fiber flakes) is deposited on the bottom of the autoclave.

After the double hydrolysis treatment, the acrylic filament flakes are subjected to a neutralization treatment to remove the caustic soda. A mixture of acetic acid and formic acid is used to bring the pH of the acrylic fibers back to neutral. Finally, downstream of the neutralization treatment, the acrylic fibers are subjected to a washing phase with water.

The following Table 10 shows the concentrations of the chemical additives present in the worn fabrics, respectively upstream and downstream of the double hydrolysis treatment in accordance with the invention. TABLE 10

As can be inferred from the data present in Table 10, the process of the present invention allows to obtain a very effective removal, of the order of 99.5% by weight, of the chemical additives originally present in the worn awnings.

Example 3 (Non-woven fabric in printed polyester for furniture)

A non-woven fabric based on polyester fibers (PES), coming from previous use in the sector of furniture, is treated.

The chemical additives that are wished to be removed are as follows:

Printing binder SOFTBIND VSO

Pigment dye SOFTBLACK B Anti-migrant resin THERMACOL BA

This non-woven fabric is first subjected to a mechanical treatment in order to fray it in the form of filaments which aggregate into flakes. These PES fiber flocks are then subjected to an alkaline hydrolysis step inside an autoclave.

Table 11 indicates the compounds used to remove the chemical additives from the PES fiber flakes and the respective concentration used inside the autoclave.

TABLE 11

SOFTCLEANER T NEW is a cationic surfactant, preparation based on fatty amine ethoxylate and glycerin. Caustic soda is used as buffering agent. The operating conditions set inside the autoclave are indicated in Table 12.

TABLE 12

After a residence time of 20 minutes, the autoclave is emptied of the treatment liquid (surfactants, buffering agents, wetting compounds, water), while the solid component (fiber flakes) is deposited on the bottom of the autoclave.

After the alkaline hydrolysis treatment, the PES fiber flakes are subjected to a neutralization treatment to remove the caustic soda. A mixture of acetic acid and formic acid is used to bring the pH of the PES fibers back to neutral. Finally, after the neutralization treatment, the PES fibers are subjected to a washing phase with water.

The following Table 13 shows the concentrations of the chemical additives present in the worn fabrics, respectively upstream and downstream of the double hydrolysis treatment in accordance with the invention.

TABLE 13

As can be inferred from the data present in Table 13, the process of the present invention allows to obtain a very effective removal, of the order of 99.5% by weight, of the chemical additives originally present in awnings based on polyester fibers.