DESC:FIELD
The present disclosure relates to a process for preparing a stable opaque polyol. Particularly, the present disclosure relates to a process for preparing a stable opaque polyol by recycling waste polyester material comprising additive.
DEFINITION
As used in the present disclosure, the following term is generally intended to have the meaning as set forth below, except to the extent that the context in which it is used indicates otherwise.
Polyester Waste – The term “Polyester Waste” refers to post-consumer chopped waste PET particles may comprise textile waste, dyes or other additives.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Polyols are important starting materials for the manufacture of polyurethane foams and other condensation polymers. Polyols need to have specific characteristics such as colour, transparency, hydroxyl value, acid value, viscosity and moisture content, depending on the application.
Conventionally, polyols are derived from dicarboxylic acid via esterification or by transesterification of polyester derivatives. The polyols obtained from these processes are transparent. Waste polyethylene terephthalate (PET) is also one of the sources of raw materials for preparing polyols. Waste polyester sources such as textile waste comprise dyes or other additives. The processes for treating the polyester for removal of such additives are impractical and costly. Further, it is difficult to obtain polyols with desired characteristics, by recycling of waste polyester material having specific characteristics.
There is, therefore, felt a need for a process for preparing polyols from waste polyester that mitigates the drawbacks mentioned hereinabove.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
Another object of the present disclosure is to provide a process for preparing a stable opaque polyol.
Still another object of the present disclosure is to provide a simple and economical process for preparing a stable opaque polyol by recycling waste polyester particles comprising additive.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a process for preparing a stable opaque polyester polyol. The process comprises the step of a) a first mixture comprising polyester particles and additive particles selected from particles of carbon black, titanium dioxide and barium sulphate is formed. Glycols are added to the first mixture of polyester particles and additive particles to obtain slurry. The catalyst particles are added to the slurry to obtain a second mixture. The second mixture is heated to a temperature in the range of 200 °C to 300 °C for a time period in the range of 3 hours to 7 hours to obtain the stable opaque polyester polyol. The stable opaque polyester polyol is cooled to obtain liquid opaque polyester polyol at 25 °C.
The present disclosure further relates to a stable opaque polyol which is in liquid form at 25 °C. The stable opaque polyol having hydroxyl value in the range of 200-300 mgKOH/gm, acid value of less than 2 mgKOH/gm, viscosity in the range of 3000 centipoise (cP) to 6000 centipoise (cP) at 25 °C and the moisture content in the range of 0.01% to 0.05%.
DETAILED DESCRIPTION
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
Polyol is one of the starting materials for the manufacturing of polyurethane foams. The characteristics of polyurethane foams depend on properties of polyols such as colour, transparency, hydroxyl value, acid value and viscosity. Conventionally, polyols can be prepared from fresh and waste polyethylene terephthalate (PET) as well. Post-consumer waste PET may comprise textile waste, dyes or other additives. The processes for preparing polyols from waste particles are difficult and do not produce polyols having specific characteristics.
The present disclosure therefore provides a simple process for producing a stable opaque polyester polyol from post-consumer waste polyester particles comprising additives. The stable polyol so obtained is opaque and is in liquid form at 25 °C.
In one aspect, the present disclosure provides a process for preparing a stable opaque polyol. The process comprises the first step of forming a first mixture of polyester particles and additive particles selected from particles of carbon black, titanium dioxide and barium sulphate.
In an embodiment, polyester particles are is chopped waste.
The polyester particles are in the form selected from popcorns, fibres, chips, flakes and mixtures thereof. In one embodiment, the polyester particles are taken in the form of popcorns. In another embodiment, the polyester particles are in taken in the form of fibres.
Typically, the source of the polyester particles is any one selected from virgin, raw fibres and waste fibres from production waste or consumer waste.
The additive particles are selected from carbon black, titanium dioxide (TiO2), barium sulphate (BaSO4) and dye compound. In one embodiment, the additive particles are carbon black. In another embodiment, the additive particles are titanium dioxide (TiO2). The additive particles may be replaced with barium sulphate (BaSO4). The additive particles may be a mixture of carbon black, titanium dioxide (TiO2) and barium sulphate (BaSO4).
The second step involves adding glycols to the first mixture to obtain slurry.
The glycols are selected from the group consisting of monoethylene glycol (MEG), diethylene glycol (DEG), triethylene glycol (TEG) and polyethylene glycol (PEG). In an embodiment, the glycols are diethylene glycol (DEG) and triethylene glycol (TEG), and the molar ratio of DEG to TEG is in the range of 1:0.5 to 1:2. In an embodiment, the molar ratio of diethylene glycol (DEG) to triethylene glycol (TEG) is 1:1.
In accordance with the present disclosure, the ratio of the polyester particles to the glycols is in the range of 1:1.5 to 1:2.5. In an embodiment, the ratio of polyester particles to the glycols is 1:2.
The third step involves adding catalyst particles to slurry to obtain a second mixture.
The catalyst particles are particles selected from the group consisting of zinc acetate, titanium glycolate, para toluene sulfonic acid, manganese acetate and stannous octoate. In an exemplary embodiment, the catalyst particles are zinc acetate.
The amount of catalyst particles added to the slurry is in the range of 0.25 wt% to 0.90 wt.% with respect to the polyester particles. In an embodiment, the amount of catalyst particles added is 0.75 wt% with respect to the polyester particles.
The fourth step involves heating the second mixture to a temperature in the range of 200 °C to 300 °C for a time period in the range of 3 hours to 7 hours to obtain a stable opaque polyester polyol.
In an embodiment, the step of heating is carried out to a temperature in the range of 200 °C to 250 °C. In another embodiment, the step of heating is carried out to a temperature in the range of 220 °C to 230 °C. In an exemplary embodiment, the step of heating of slurry is carried out at 225 °C.
In an embodiment, the step of heating is carried for the time period in the range of 4 to 6 hours. In an exemplary embodiment, the step of heating is carried out for 5 hours. The step of heating is carried out at atmospheric pressure to sub-atmospheric pressure.
The fifth step involves, cooling stable opaque polyester polyol to obtain opaque liquid polyester polyol at 25 °C.
In an embodiment, the opaque polyester polyol is subjected to nitrogen bubbling followed by applying vacuum to reduce the residual moisture.
The process further comprises a step of recovering unreacted glycols from opaque polyol. The recovered glycol compounds are further recycled to the second step of the reaction, thereby making the process environment friendly and economic.
In another aspect, the present disclosure provides a stable opaque polyol, having hydroxyl value in the range of 200-300 mgKOH/gm, acid value of less than 2 mgKOH/gm, viscosity in the range of 3000 centipoise (cP) to 6000 centipoise (cP) at 25 °C and the moisture content in the range of 0.01% to 0.05%.
In an embodiment, the opaque polyol is having hydroxyl value of 256.5 mgKOH/gm, acid value of 0.9 mgKOH/gm, viscosity of 4780 centipoise (cP) at 25 °C and the moisture content of 0.03%.
In another embodiment, the opaque polyol is having hydroxyl value of 242.6 mgKOH/gm, acid value of 0.8 mgKOH/gm, viscosity of 4451 centipoise (cP) at 25 °C and moisture content of 0.04%.
In still another embodiment, the opaque polyol is having hydroxyl value of 232.8 mgKOH/gm, acid value of 0.9 mgKOH/gm and viscosity of 3850 centipoise (cP) at 25 °C and moisture content of 0.02%.
In yet another embodiment, the opaque polyol is having hydroxyl value of 234.4 mgKOH/gm, acid value of 1 mgKOH/gm, viscosity of 4200 centipoise (cP) at 25 °C and moisture content of 0.04%.
The viscosity of the polyester polyol depends on the amount of additive present in the waste polyester particles. The waste polyester particles with high levels of additive results in higher viscosity of polyols.
In an embodiment, the polyester polyol having a viscosity in the range of 3000 centipoise (cP) to 6000 centipoise (cP) are used for diluting polyol blends selected from the group consisting of aliphatic polyether, aromatic polyether and polyester polyols.
Further, the stable opaque polyol of the present disclosure is feasible for use in several applications requiring various levels of opacity and/or colour such as the manufacture of polyurethane foams for insulation, footwear soles and the like.
The presence of an additive such as carbon black in the polyester polyols provides the feasibility of using the polyester polyols for several applications requiring dark coloured products such as the manufacture of black polyurethane foams for insulation, footwear soles and the like.
The presence of an additive such as titanium dioxide in the polyester polyols provides the feasibility of using the polyester polyols for several applications requiring opaque products. Further, the process of the present disclosure is economical as it uses waste polyester consisting of additive. The process is environment friendly as it recycles waste polyester particles. The process also saves cost of treating the starting polyester particles for removal of additive. Furthermore, the process enables recovering the glycol compounds which are unreacted or obtained as by-products during homogenizing step and enables further recycling/re-use of the recovered glycol compounds in the process, making the process environmental friendly and economical.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.

EXPERIMENTAL DETAIL:
Experiment 1: Preparation of opaque polyol
Polyester particles and additive particles of carbon black (200 grams) were mixed to obtain a first mixture to which 272 grams of mixture of diethylene glycol (DEG) and triethylene glycol (TEG) (1:1 molar ratio) was added to obtain slurry. Zinc acetate particles (1.5 gram) were added to the slurry to obtain second mixture. The second mixture was homogenized under stirring to obtain homogenized mixture. The homogenized mixture was heated under stirring at 225 °C for 5 hours to obtain opaque polyester polyol. The opaque polyester polyol was cooled to obtain liquid opaque polyester polyol. The opaque polyester polyol was subjected to nitrogen bubbling followed by applying vacuum to reduce the residual moisture. The polyester polyol were evaluated for acid value, hydroxyl value, viscosity and moisture content. The properties of polyols obtained are summarized in table 1.
Experiment 2
Similar to experiment 1, polyols were prepared from polyester particles and particles of titanium dioxide. The properties of polyols obtained are summarized in table 1.
Table 1
Properties of polyols obtained from polyester
Expt.No. Polyester used Additive Form of Polyester Hydroxyl value in mgKOH/g Acid value in mgKOH/g Viscosity in
cP @ 25 °C % moisture content Appearance
1 Polyethylene terephthalate (PET) carbon black Popcorn 256.5 0.9 4780 0.03 Black opaque liquid even after 60 days
2 Polyethylene terephthalate (PET) carbon black Popcorn 242.6 0.8 4451 0.04 Black opaque liquid even after 60 days
3 Polyethylene terephthalate (PET) titanium dioxide Popcorn 232.8 0.9 3850 0.02 Yellow opaque liquid even after 60 days
4 Polyethylene terephthalate (PET) titanium dioxide Popcorn 234.4 1 4200 0.04 Yellow opaque liquid even after 60 days
As observed in table 1, the opaque polyol prepared by recycling waste PET, demonstrated acceptable properties of polyol such as hydroxyl value, acid value, viscosity and moisture content.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a process for preparing a stable opaque polyester polyol, that:
? provides stable opaque polyester polyol;
? converts the waste polyester particles and additive particles into high value products such as polyester polyols;
? recycles waste polyester particles and additive particles without any need for treating/processing the waste polyester particles; and
? recovers and recycles/reuses glycol compounds making the process environment friendly and economical.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
,CLAIMS:WE CLAIM:
1. A process for preparing a stable opaque polyester polyol, said process comprising the following steps:
a) forming a first mixture comprising polyester particles and additive particles selected from particles of carbon black, titanium dioxide and barium sulphate;
b) adding glycols to said first mixture to obtain slurry;
c) adding catalyst particles to said slurry to obtain a second mixture;
d) homogenizing said second mixture to form a homogenized mixture;
e) heating said homogenized mixture under stirring to a temperature in the range of 200 °C to 300 °C for a time period in the range of 3 hours to 7 hours to obtain a stable opaque polyester polyol; and
f) cooling said stable opaque polyester polyol formed to obtain liquid opaque polyester polyol at 25 °C.
2. The process as claimed in claim 1, wherein said polyester particles is chopped waste.
3. The process as claimed in claim 1, wherein said polyester particles are selected from popcorns, fibres, chips, flakes and mixtures thereof.
4. The process as claimed in claim 1, wherein the ratio of said polyester particles to said glycols is in the range of 1:1.5 to 1:2.5.
5. The process as claimed in claim 1, wherein said glycols are selected from the group consisting of monoethylene glycol (MEG), diethylene glycol (DEG), triethylene glycol (TEG) and polyethylene glycol (PEG).
6. The process as claimed in claim 1, wherein said glycols contains diethylene glycol (DEG) and triethylene glycol (TEG), and wherein the molar ratio of DEG to TEG is in the range of 1:0.5 to 1:2.
7. The process as claimed in claim 7, wherein the molar ratio of diethylene glycol (DEG) to triethylene glycol (TEG) is 1:1.
8. The process as claimed in claim 1, wherein said catalyst particles are particles selected from the group consisting of zinc acetate, titanium glycolate, para toluene sulfonic acid, manganese acetate and stannous octoate.
9. The process as claimed in claim 1, wherein, the amount of said catalyst particles is in an amount in the range of 0.25 wt% to 0.90 wt.% with respect to the polyester particles.
10. The process as claimed in claim 1, wherein heating said homogenized mixture under stirring is carried out to a temperature in the range of 220 °C to 230 °C.
11. The process as claimed in claim 1, wherein heating said homogenized mixture under stirring is carried out for a time period in the range of 4 hours to 6 hours.
12. A stable opaque polyol which is in liquid form at 25 °C.

13. The polyol as claimed in claim 12, having hydroxyl value in the range of 200-300 mgKOH/gm, acid value of less than 2 mgKOH/gm, viscosity in the range of 3000 centipoise (cP) to 6000 centipoise (cP) at 25 °C and the moisture content in the range of 0.01% to 0.05%.