Polyols with increased recycling content and a method for producing a polyurethane foam from these polyols

Abstract

The invention relates to the polyols with increased recycling content using different waste materials, a method for producing a rigid polyurethane foam from these polyols, and a polyurethane foam produced by said method.

Description

[0001] POLYOLS WITH INCREASED RECYCLING CONTENT AND A METHOD FOR PRODUCING A POLYURETHANE FOAM FROM THESE POLYOLS

[0002] Technical Field of the Invention

[0003] The invention relates to the polyols with increased recycling content using different waste materials, a method for producing a rigid polyurethane foam from these polyols, and a polyurethane foam produced by said method. The polyurethane foam of the invention comprises PET (polyethylene terephthalate) and PUR (polyurethane)-based waste material. With said method, the carbon footprint is reduced and the production costs are reduced.

[0004] State of the Art

[0005] Today, as in the past, the need for energy and efforts to access energy resources are increasing rapidly. On the other hand, the world is rapidly running out of energy resources. In recent years, the issue of energy efficiency has become important due to the accelerating increase in energy demand, the pressure of environmental factors resulting from energy consumption and the increase in energy costs. One of the technologies enabling energy efficiency is insulation. Today, thermal insulation is provided by materials such as glass / stone wool, polymeric foams and vermiculite. Among these materials, polymeric foams stand out due to their low thermal conductivity. Polymeric foams are found almost everywhere due to their advantageous properties over equivalent materials. The most important class of polymeric foams are polyurethane foams (PUFs), whose low density and thermal conductivity combined with strong mechanical properties make them excellent thermal and sound insulators as well as structural and comfort materials. Despite the wide range of applications, the production of PUFs is still heavily dependent on petroleum, so this industry needs to adapt to increasingly stringent regulations and fastidious consumers [1].

[0006] Rigid polyurethane foams, a composite material, are known to be one of the most effective thermal insulation materials, offering excellent mechanical properties, with closed cell structure, and inflexible, compact mesh structure. It is produced by mixing and reacting two liquid chemicals, polyol and isocyanate (MDI), which is a petroleum- based material, and by foaming the polymerized mixture with the occurred carbon dioxide gas in the mixture. Various properties of PUFs can be controlled by changing the functionality of the polyol. For example, increasing polyol functionality without changing the molecular weight leads to a slight increase in foam stiffness and a small decrease in tensile strength, shear strength and elongation, whereas increasing the equivalent weight of a polyol (molecular weight divided by functionality) increases its tensile strength and elongation while maintaining polyol functionality. In this way, polyurethane, which is one of the most widely used commercial polymeric foams in the world due to the manipulability of the properties of the end product, ease of processability, affordable costs, low thermal conductivity values and high compressive tensile strength values, has a wide variety of applications in the construction and insulation industry, with only insulation applications accounting for 5% of the world market. In 2020, the total global sandwich panel market size was realized as 1.45 billion dollars, and it is expected that the market size will reach 2.75 billion dollars in 2027, exhibiting a compound annual growth rate (CAGR) of 9.6% in 2020-2028 [3]. In Turkey, the sandwich panel market has been increasing on an m2-basis over the years, with the total market size reaching 207.5 billion Turkish liras in 2020. The average amount of waste generated from these productions is approximately 2% of total production and will increase linearly with the growth of the market. One of the problems encountered in the use of rigid foams is that they are very difficult to recycle due to their cross-linking. Waste polyurethane foams generated in panel companies cannot be recycled within the company. For this reason, these panels, which constitute approximately 2% of production, are stored in landfills and sent to recycling facilities. The foams sent to disposal are disposed of by incineration in recycling facilities and the harmful gases such as CO2, HCI, HCN released during this process do not exhibit an environmentally friendly approach by causing environmental pollution. Chemical processes such as hydrolysis, glycolysis and aminolysis, in which waste polyurethane foams are depolymerized, can be used to produce semi-finished products that can be mixed with commercial polyols, but only in limited proportions. As the percentage of addition of the chemical recycled from polyurethane foam to commercial polyol increases, quality values such as compressive / tensile strength, thermal conductivity coefficient, cell size are negatively affected. Therefore, the production of polyurethane foam generates a lot of waste materials and current recycling processes are insufficient to recycle all of the waste materials. As a result, the environment and ecosystem are damaged. Another waste derivative that can be added to polyols in the state of the art is PET waste. Polyethylene terephthalate) (PET) is a thermoplastic polyester widely used in the production of high-strength fibers and soft drink bottles. Since PET plastics are easy to produce and have the advantage of low cost, their use is increasing rapidly all over the world and they cause a solid waste spread because they do not disappear in nature. Patent application JPS608333A in the state of the art relates to a method for producing a polyol from polyethylene terephthalate (PET) resin. In said document, a raw material polyol for isocyanate-based resin is obtained by reacting a terephthalate resin with an active hydrogen compound having 2 to 4 functional groups, optionally a polycarboxylic acid or an acid anhydride thereof, at 180 to 280°C. However, polyols derived from PET waste have several significant disadvantages such as high viscosity, incompatibility with physical foaming agents and crystallization at room temperature [4], For this reason, the use of polyols with these disadvantages is not effective in the production of polyurethane foam. Moreover, in the state of the art, in the production of rigid polyurethane foam, waste polyurethane (PUR) material is used in addition to waste PET. One of the problems encountered in the use of PUR is that they are very difficult to recycle due to their crosslinking. Therefore, PUR, a thermosetting polymer, cannot be recycled by melting, and PUR also has problems such as the production of toxic and poisonous gases during combustion, which cause pollution and are corrosive to furnace apparatus.

[0007] Patent application CN101270203A in the state of the art discloses a process for the preparation of polyester polyols, in particular using industrial or household waste. Here, PET-based waste and epoxy vegetable oil are used as waste materials and a polyol with a hydroxyl value ranging from 270 to 700 mgKOH / g is prepared. It is reported that the structure and mechanical strength of said polyol is superior to that of petroleum polyether polyol and the foaming process is stable. It is explained that the appropriate amount of primary hydroxyl groups in the structure saves catalyst during the foaming reaction. However, in said document, the vacuum treatment is preferably applied in the range of 5-200 mmHg for 1 -10 hours, which implies an extra process. Furthermore, the OH numbers of polyols used in rigid polyurethanes are in the maximum range of 300-500 mgKOH / g for a pump used in a standard production line and the appropriate viscosity value for this range is 2500 cp. In order to obtain a homogeneous mixture, the components must be mixed at pressures of 100 bar and above. The pumps and fluids currently used are theoretically not capable to pressurize the fluids with a viscosity of above 2500 cp to this pressure. Therefore, viscosity is an important parameter. An improvement in the production of rigid polyurethane foam is required due to the limitations and inadequacies of the solutions in the state of the art, the use of polyol, a petroleum-based chemical, in the production of polyurethane foam and the resulting environmental problems, and the inability to recycle waste polyurethane foam generated in panel companies, polyols obtained from PET wastes to be used in polyurethane foam production, with high viscosity, incompatibility with physical foaming agents and crystallization properties at room temperature, as well as adding the waste materials to commercial polyol in certain proportions and the limited content of recycled materials added to polyol, and difficult recycling of waste PUR.

[0008] Summary and Objects of the Invention

[0009] In the invention, the polyols with increased recycling content using different waste materials, a method for producing a rigid polyurethane foam from these polyols, and a polyurethane foam produced by said method are described. The polyurethane foam of the invention comprises PET (polyethylene terephthalate) and PUR (polyurethane)- based waste material. With said method, the carbon footprint is reduced and the production costs are reduced.

[0010] The object of the invention is to produce environmentally friendly rigid polyurethane foam at low cost. The foam material of the invention provides the recycling and recovery of the waste polyurethane foams found in panel factories as raw materials. The polyols used in the invention comprises PET (polyethylene terephthalate) and PUR (polyurethane)- based waste material. Since said foam is derived from recycled polyols, its production requires low cost compared to the already produced polyurethane foams. Furthermore, since the number of petroleum-based polyols used in the invention is reduced, the polyurethane foam produced is an environmentally friendly product. Normally in the panel line, 100% petroleum-derived polyols are used, whereas this ratio is reduced to 30% and 70% of the final polyurethane foam consists of recycled polyols with the present invention.

[0011] An object of the invention is to provide polyols with increased recycling content. In the invention, polyols to be used as raw materials in the production of rigid polyurethane foam are obtained from PET (polyethylene terephthalate) and PUR (polyurethane)- based waste materials. A further object of the invention is to produce a polyurethane foam with high strength properties. By doping the material of the invention with waste PET, the presence of aromatic rings is increased, making the foams more rigid and resulting in an increase in the accompanying compressive strength. At the same time, the tensile properties are improved due to higher crosslinking of the foams with the recycled components.

[0012] Detailed Description of the Invention

[0013] The invention relates to the polyols with increased recycling content using different waste materials, a method for producing a rigid polyurethane foam from these polyols, and a polyurethane foam produced by said method.

[0014] A polyurethane foam of the invention comprises 10.94% gram of commercial polyol, 25.55% gram of polyol obtained from PET and PUR wastes, 58.39% gram of isocyanate, 1 .09% gram of cell regulator, 1 .09% gram of catalyst and 2.93% gram of blowing agent. Said blowing agent is preferably pentane and said cell regulator is preferably a silicone- based nonionic surfactant. In a preferred embodiment of the invention, a polyurethane foam comprises 3 gram of commercial polyol, 7 gram of polyol obtained from PET and PUR wastes, 16 gram of isocyanate, 0.3 gram of cell regulator, 0.3 gram of catalyst and 0.8 gram of blowing agent.

[0015] A method for producing a polyurethane foam of the invention comprises the process steps of: i. grinding the waste polyurethane foams into powder and adding them to the reactor, ii. adding a destructive agent to the reactor, iii. adding an auxiliary reactive tertiary amine source to the reactor, iv. performing a glycolysis reaction of a mixture containing powdered waste polyurethane foam, a destructive agent and an auxiliary reactive tertiary amine source in a reactor, v. reacting PET waste in the presence of a catalyst with the glycolysis product resulting from the process step (iv) to obtain polyols with increased recycling content, vi. adding the material obtained in the process step (v) to the commercial polyol. In a different embodiment of the invention, a method for producing a polyurethane foam of the invention comprises the process steps of: i. grinding waste polyurethane foams into powder with an average diameter of 500- 65 micrometers and adding 15-45% by mass of waste polyurethane to the reactor, ii. adding 55-75% by mass of the destructive agent to the reactor, iii. adding 5-50% by mass of an auxiliary reactive tertiary amine source to the reactor, iv. performing the glycolysis reaction of the mixture containing powdered waste polyurethane foam, destructive agent and an auxiliary reactive tertiary amine source in the reactor under atmospheric conditions, with a reaction temperature of 120-220°C and a reaction time of 1-8 hours, v. obtaining polyols with increased recycling content by reacting PET waste in the presence of a catalyst at a rate of 0.1 -1% by mass with the glycolysis product obtained in the process step (iv) under atmospheric conditions at 180-250°C for 1 -8 hours, vii. adding 40-70% of the material obtained in the process step (v) to the commercial polyol.

[0016] In a different embodiment of the invention, a method for producing a polyurethane foam of the invention comprises the process steps of: i. grinding waste polyurethane foams into powder with an diameter of 500-65 micrometers and adding 44% by mass of waste polyurethane to the reactor, ii. adding 46% by mass of the destructive agent to the reactor, iii. adding 10% by mass of an auxiliary reactive tertiary amine source to the reactor, iv. performing the glycolysis reaction of the mixture containing powdered waste polyurethane foam, destructive agent and an auxiliary reactive tertiary amine source in the reactor under atmospheric conditions, with a reaction temperature of 180°C and a reaction time of 3 hours, v. obtaining polyols with increased recycling content by reacting 39.6 gram of PET waste in the presence of 0.5 gram of a catalyst with 60.4 gram of the glycolysis product obtained in the process step (iv) under atmospheric conditions at 180- 250°C for 1-8 hours, viii. adding 60% of the material obtained in the process step (v) to the commercial polyol. In the invention, after the panels, which are waste polyurethane foams, are separated from the sheets, they are ground into powder with an average diameter of approximately 500-65 micrometers and added to the reactor. Furthermore, glycol is added to the reactor as a destructive agent, which binds to the functional groups of urethane, subsequently breaks the bonds and releases polyols and amines. Preferably, ethylene glycol, diethylene glycol, 1 ,2-propanediol, dipropylene glycol, glycerol, trimethylolpropane, monoethylene glycol, pentaerythritol, mannitol, sorbitol, 2-butylene glycol, 1 ,3-butylene glycol, 1 ,4-butanediol, 2-methyl-1 ,3-propanediol, pentaerythritol, neopentyl glycol, 3- cyclobutanediol, 3-methyl-1 ,5-pentanediol, 1 ,4-cyclohexanedimethanol, 1 ,3- cyclohexanedimethanol, bisphenol A ethoxylates, dipropylene glycol, triethylene glycol, 1 ,6-hexanediol, tripropylene glycol or tetraethylene glycol are used. In addition to the destructive agents, an auxiliary reactive tertiary amine source is added to the reactor. The auxiliary reagent tertiary amine source is preferably trimethylamine, dimethylethanolamine or trimethanolamine. The auxiliary reagents act as catalysts and increase the electrophilicity of the isocyanate functional group and increase the reaction rate between polyol and polyisocyanate, facilitating the binding of polyols and the formation of PUs under very short and uncontrollable reaction conditions. The glycolysis reaction of the mixture containing powdered waste polyurethane foam, destructive agent and an auxiliary reactive tertiary amine source is performed in the reactor under atmospheric conditions, with a reaction temperature of 120-220°C and a reaction time of 1 -8 hours, The glycolysis product resulting from this reaction is reacted with PET waste in the presence of a catalyst under atmospheric conditions at 180-250°C for 1-8 hours. Said catalyst is preferably tetrabutyl titanate, antimony trioxide, toluene sulfonic acid, zinc acetate, tetrabutyl titanate, zinc acetate or tin octoate. In the present art, the polyols derived from waste PUR or waste PET can be added to the commercial polyols at a maximum rate of 30% by mass, whereas the polyols derived from waste PUR and PET materials obtained by the method of the invention can be added at a rate of 40-70% by mass. A cell regulator, catalyst and blowing agent, polymeric MDI, were then used to obtain the polyurethane foams of the invention.

[0017] The hydroxyl value of the polyol obtained by the method of the invention is 250 to 550 mgKOH / g. The viscosity of the obtained raw material is between 800 and 2500 cp at a temperature of 25°C and the rigid polyurethane foam material of the invention has TS EN 826 (Compressive strength) >0.095 MPa, TS EN 1607 (Tensile strength) >0.080 MPa, TS EN 12667 (Thermal conductivity): 0.022 W / mK. Industrial Applicability of the Invention

[0018] The invention relates to the polyols with increased recycling content using different waste materials, a method for producing a rigid polyurethane foam from these polyols, and a polyurethane foam produced by said method, and is applicable to the industry.

[0019] The invention is not limited to the above descriptions and the person skilled in the art can readily present other different embodiments of the invention. These should be considered within the protection scope of the invention claimed by the claims.

[0020] REFERENCES

[0021] [1] Gama, N. V., Ferreira, A., & Barros-Timmons, A. (2018, September 27). Polyurethane foams: Past, present, and future. Materials (Basel, Switzerland). [2] Ashida K. Polyurethane and Related Foams Chemistry and Technology. Taylor &

[0022] Francis Group; Boca Raton, FL, USA: 2007.

[0023] [3] Sandwich panels market size, share, scope, growth & forecast. Verified Market Research. (2023, June 7).

[0024] [4] Development of innovative polyol systems from recycled polyethylene terephthalate and renewable raw materials for rigid polyurethane foams - RTU E. books. (2023, February 6).

Claims

CLAIMS1. A polyurethane foam, wherein it comprises commercial polyol, polyol derived from waste PET (polyethylene terephthalate) and waste PUR (polyurethane), isocyanate, cell regulator, catalyst and blowing agent.

2. A polyurethane foam according to claim 1 , wherein it comprises 10.94% gram of commercial polyol, 25.55% gram of polyol obtained from PET and PUR wastes, 58.39% gram of isocyanate, 1 .09% gram of cell regulator, 1 .09% gram of catalyst and 2.93% gram of blowing agent.

3. A polyurethane foam according to claim 1 or 2, wherein it comprises 3 gram of commercial polyol, 7 gram of polyol obtained from PET and PUR wastes, 16 gram of isocyanate, 0.3 gram of cell regulator, 0.3 gram of catalyst and 0.8 gram of blowing agent.

4. A polyurethane foam according to any one of claims 1 -3, wherein said blowing agent is pentane and said cell regulator is a silicone-based nonionic surfactant.

5. A polyurethane foam according to any one of claims 1 -3, wherein said catalyst is tetrabutyl titanate, antimony trioxide, toluene sulfonic acid, zinc acetate, tetrabutyl titanate, zinc acetate or tin octoate.

6. A method for producing a polyurethane foam according to claim 1 , wherein it comprises the process steps of: i. grinding the waste polyurethane foams into powder and adding them to the reactor, ii. adding a destructive agent to the reactor, iii. adding an auxiliary reactive tertiary amine source to the reactor, iv. performing a glycolysis reaction of a mixture containing powdered waste polyurethane foam, a destructive agent and an auxiliary reactive tertiary amine source in a reactor, v. reacting PET waste in the presence of a catalyst with the glycolysis product resulting from the process step (iv) to obtain polyols with increased recycling content,vi. adding the material obtained in the process step (v) to the commercial polyol.

7. A method according to claim 6, wherein it comprises the process steps of: i. grinding waste polyurethane foams into powder with an average diameter of 500-65 micrometers and adding 15-45% by mass of waste polyurethane to the reactor, ii. adding 55-75% by mass of the destructive agent to the reactor, iii. adding 5-50% by mass of an auxiliary reactive tertiary amine source to the reactor, iv. performing the glycolysis reaction of the mixture containing powdered waste polyurethane foam, destructive agent and an auxiliary reactive tertiary amine source in the reactor under atmospheric conditions, with a reaction temperature of 120-220°C and a reaction time of 1-8 hours, v. obtaining polyols with increased recycling content by reacting PET waste in the presence of a catalyst at a rate of 0.1 -1% by mass with the glycolysis product obtained in the process step (iv) under atmospheric conditions at 180-250°C for 1-8 hours, vi. adding 40-70% of the material obtained in the process step (v) to the commercial polyol.

8. A method according to claim 7, wherein it comprises the process steps of: i. grinding waste polyurethane foams into powder with an average diameter of 500-65 micrometers and adding 44% by mass of waste polyurethane to the reactor, ii. adding 46% by mass of the destructive agent to the reactor, iii. adding 10% by mass of an auxiliary reactive tertiary amine source to the reactor, iv. performing the glycolysis reaction of the mixture containing powdered waste polyurethane foam, destructive agent and an auxiliary reactive tertiary amine source in the reactor under atmospheric conditions, with a reaction temperature of 180°C and a reaction time of 3 hours, v. obtaining polyols with increased recycling content by reacting 39.6 gram of PET waste in the presence of 0.5 gram of a catalyst with 60.4 gram ofthe glycolysis product obtained in the process step (iv) under atmospheric conditions at 180-250°C for 1-8 hours, vi. adding 60% of the material obtained in the process step (v) to the commercial polyol.

9. A method according to any one of claims 6-8, wherein in the process step (ii), said destructive agent is ethylene glycol, diethylene glycol, 1 ,2-propanediol, dipropylene glycol, glycerol, trimethylolpropane, monoethylene glycol, pentaerythritol, mannitol, sorbitol, 2-butylene glycol, 1 ,3-butylene glycol, 1 ,4- butanediol, 2-methyl-1 ,3-propanediol, pentaerythritol, neopentyl glycol, 3- cyclobutanediol, 3-methyl-1 ,5-pentanediol, 1 ,4-cyclohexanedimethanol, 1 ,3- cyclohexanedimethanol, bisphenol A ethoxylates, dipropylene glycol, triethylene glycol, 1 ,6-hexanediol, tripropylene glycol or tetraethylene glycol.

10. A method according to any one of claims 6-8, wherein in the process step (iii), said auxiliary reactive tertiary amine source is trimethylamine, dimethylethanolamine or trimethanolamine.

11. A method according to any one of claims 6-8, wherein in the process step (iii), said catalyst is tetrabutyl titanate, antimony trioxide, toluene sulfonic acid, zinc acetate, tetrabutyl titanate, zinc acetate or tin octoate.

12. Polyurethane foam produced by a method according to any one of claims 6-8.