Glycolysis process for converting polyurethane foam into useful dispersions

Abstract

Polyol dispersions are prepared by the chemical decomposition of polyurethane foam. The starting foam is compressed, deaerated, combined with polyols in a non-reverse-mixed tubular reactor, wetted, and then pulverized to produce the polyol dispersion. This rapidly generates a rapidly pulverizing reaction mixture. The process is well-suited for continuous operation. Polyol dispersions are useful for the production of polyurethane.

Description

Technical Field

[0001] The present invention relates to a glycolysis method for converting polyurethane foam into useful products.

Background Art

[0002] Polyurethane foams are produced in very large quantities worldwide. Polyurethane foams vary widely in properties and end uses. Flexible foams are used inter alia as cushions for furniture, vehicle seats and bedding. Mattresses often contain significant amounts of flexible polyurethane foam. Rigid polyurethane foams are widely used in thermal insulation applications such as insulation for electrical appliances and buildings, insulated trucks and rail vehicles, and similar products.

[0003] These products present a very serious end-of-life disposal problem. Heretofore, these products have been landfilled, but in many parts of the world, landfills are becoming scarce and unable to accept large quantities of waste foam. Waste foam can be combusted to recover energy, but doing so releases carbon dioxide. Some polyurethane foams are recycled by pulverizing them to form small particles that can be incorporated into new foam products. However, opportunities to do this are limited.

[0004] Many attempts have been made to convert polyurethane foams back into useful starting materials via various chemical degradation processes. These include hydrolysis processes in which the foam is reacted with water at elevated temperature and pressure, glycolysis processes in which the foam is reacted with low molecular weight diols, acidolysis processes in which the foam is reacted with carboxylic acids or anhydrides, and aminolysis processes in which the foam is reacted with primary amine compounds. All of the aforementioned chemical degradation processes produce isocyanate-reactive mixtures containing polyols and / or polyamines. These reactive mixtures, by themselves or together with virgin polyols, can react with polyisocyanates to produce more polyurethane or polyurea products.

[0005] Hybrid processes combining two or more of these chemical decomposition approaches, such as glycolysis-hydrolysis and glycolysis-acid decomposition processes, are also well known. An interesting hybrid chemical decomposition process is the glycolysis-acid decomposition process described in U.S. Patent No. 11,124,623. In this process, spent polyurethane foam is reacted with a carboxylic acid or anhydride and 400 to 6000 molar mass of polyether polyol, and then further reacted with a short-chain diol or triol in a combined glycolysis-acid decomposition process.

[0006] The chemical decomposition process of polyurethane foams is typically operated in batch reactors. Batch processes are less desirable on a large industrial scale because cycle times can be very long. The process described in U.S. Patent No. 11,124,623, in particular, typically requires batch cycle times of 12 hours or more to heat the starting materials to the required temperature, carry out the reaction, and then cool the reaction products. The long cycle times are partly due to the use of somewhat higher molecular weight polyether polyols as glycol components. These polyols are viscous even at processing temperatures and penetrate the foam very slowly compared to the lower molecular weight polyols used in conventional glycolysis methods. Furthermore, higher molecular weight polyols are generally used in larger weight proportions due to their relatively fewer hydroxyl groups. Continuous processes potentially offer significant advantages on a large scale if the chemical decomposition process can be adapted to continuous operation.

[0007] Several attempts have been made to carry out a continuous chemical decomposition process in an extruder or similar apparatus. U.S. Patent No. 4,051,212 describes hydrolyzing a polyurethane foam in a twin-screw extruder to produce toluenediamine and polyether hydrolysis products. German Patent No. 3232461A describes glycolysis of a polyurethane foam in a twin-screw extruder using propylene glycol and other short-chain diols as glycolytic agents, followed by cooling the product mixture in a refrigerated tank. [Overview of the project]

[0008] In one embodiment, the present invention is a process for producing a polyol dispersion from a polyurethane foam, wherein the process is a) A step of continuously supplying a component comprising (component i) a polyurethane foam and (component ii) a polyether polyol having a weight-average molecular weight of 400 to 8000 g / mol to a non-reverse mixing tubular reactor having a rotating screw including a forward element, b) A step of compressing and degassing polyurethane foam in a non-reverse-mixing tubular reactor at a temperature of 10 to 300°C by the action of a rotating screw, combining the compressed and degassed polyurethane foam with component ii, wetting it to form a reaction mixture, and then c) A step of pulverizing a reaction mixture at a reaction temperature of 150 to 300°C in order to chemically decompose a polyurethane foam and produce a polyol dispersion.

[0009] This aspect of the present invention provides a process that can convert polyurethane foam into a useful polyol dispersion by reaction with a polyol with a molecular weight of 400 to 8,000 in a significantly reduced cycle time. The cycle time in the process described in U.S. Patent No. 11,124,623 is typically in the range of 10 to 15 hours on an industrial scale. In the present invention, these cycle times can be reduced to 5 hours or less, and in some cases to less than 1 hour. The pulverization process can be carried out continuously in a batch reactor, in which case the present invention offers the advantages of continuous operation. Alternatively, the pulverization process can be carried out in another tank reactor, which may be, for example, a batch reactor or a continuous stirred tank reactor (CSTR). Even in the latter case, a significantly reduced cycle time is obtained, largely due to the rapid defoaming of the foam and the efficient wetting of the foam with the polyether polyol.

[0010] In a second aspect, the present invention provides a process for producing a polyol dispersion from a polyurethane foam, wherein the process is: A step of continuously supplying a component comprising (component i) polyurethane foam, (component ii) polyol, and (component iii) dicarboxylic acid and / or dicarboxylic acid anhydride to a mixing section of a non-reverse-mixing tubular reactor, wherein the mixing section of the non-reverse-mixing tubular reactor has a rotating screw including a forward element, The process involves compressing and degassing the polyurethane foam in a mixing section, wetting the compressed and degassed polyurethane foam in the mixing section with components ii and iii to form a reaction mixture, and heating the reaction mixture to a reaction temperature of 150-300°C. A process in which the reaction mixture is continuously advanced from the mixing section into the downstream section of the non-reverse-mixing tubular reactor while maintaining the reaction mixture temperature in the downstream section of the non-reverse-mixing tubular reactor, thereby pulverizing the reaction mixture, chemically decomposing the polyurethane foam, and generating a polyol dispersion in the non-reverse-mixing tubular reactor, The process includes a step of continuously removing a polyol dispersion from the outlet end of a non-reverse-mixing tubular reactor.

[0011] In a third aspect, the present invention relates to a process for producing a polyol dispersion from a polyurethane foam, the process being: A step of continuously supplying a component comprising (component i) polyurethane foam and (component ii) polyol to the mixing section of a non-reverse-mixing tubular reactor, wherein the mixing section of the non-reverse-mixing tubular reactor has a rotating screw including a forward element, The process involves compressing and degassing the polyurethane foam in a mixing section, wetting the compressed and degassed polyurethane foam in a mixing section with component ii to form a reaction mixture, and heating the reaction mixture to a reaction temperature of 150-300°C. A process in which the reaction mixture is continuously advanced from the mixing section into the downstream section of the non-reverse-mixing tubular reactor while maintaining the reaction mixture temperature in the downstream section of the non-reverse-mixing tubular reactor, thereby pulverizing the reaction mixture, chemically decomposing the polyurethane foam, and generating a polyol dispersion in the non-reverse-mixing tubular reactor, The process includes continuously removing a polyol dispersion from the outlet end of a non-reverse-mixing tubular reactor and cooling the dispersion to a temperature of 20-30°C without applying refrigeration.

[0012] In a fourth aspect, the present invention relates to a process for producing a polyol dispersion from a polyurethane foam, the process being: A step of continuously supplying components, including (component i) polyurethane foam and (component ii) polyol, to an extruder, wherein the extruder has a rotating screw including a forward element, The process involves compressing and degassing a polyurethane foam in an extruder, wetting the compressed and degassed polyurethane foam with component ii in the extruder to form a reaction mixture, and heating the reaction mixture to a reaction temperature of 150-300°C. The process involves maintaining the reaction temperature in a static mixer while continuously advancing the reaction mixture from an extruder into the static mixer, pulverizing the reaction mixture within the static mixer, and chemically decomposing the polyurethane foam to produce a polyol dispersion. The process includes a step of continuously removing the polyol dispersion from the outlet end of a static mixer.

[0013] In the present invention, polyurethane foam, polyol, and optionally other components described above are continuously supplied to a non-reverse-mixed tubular reactor. The tubular reactor provides one or more ports or other openings through which the starting materials are introduced. Suitable apparatus for supplying foam and other solid starting materials include gravimetric feeders and "crankers" for mechanically pushing the foam into the ports of the tubular reactor. Liquid starting materials can be introduced in any convenient way, for example, by using various types of gravimetric feeders and pumps, typically associated with weighing devices for controlling the introduction rate. Any two or more of the starting materials can be premixed before being supplied to the tubular reactor.

[0014] "Non-backmixed" or "non-backmixed" means that the material flowing through the tubular reactor generally moves downstream from the inlet to the removal point without moving "back" upstream, i.e., towards the inlet. "Tubular" means that the reactor has an elongated internal cavity having a length-to-diameter ratio of preferably at least 5, at least 10, at least 20, or any larger value such as up to 500, up to 100, or up to 50. The tubular reactor may have any cross-sectional shape, including circular, elliptical, polygonal, or "figure-eight" shapes, and the cross-sectional shape and area may be constant or not constant along the entire length of the tubular reactor. If the cross-section of the internal cavity is not circular, the diameter shall be the diameter of a circle having the same area as the cross-sectional area of ​​the internal cavity. If the cross-sectional area of ​​the internal cavity is not constant, the length-to-diameter ratio shall be the total length of the internal cavity of the tubular reactor divided by its minimum cross-sectional area.

[0015] At least a portion of the non-reverse-mixing tubular reactor has a rotating screw including a forward element. In a particularly preferred embodiment, a single-screw extruder, more preferably a twin-screw extruder, constitutes at least the mixing section of the tubular reactor, i.e., the portion of the tubular reactor where the polyurethane foam is degassed, combined with a polyether polyol, and wetted with the polyether polyol. In such embodiments, the operation of the screw provides the power for mixing and for moving the reactants through the reactor from various inlets to outlets. [Modes for carrying out the invention]

[0016] In some embodiments, a single-screw or twin-screw extruder constitutes the entire non-reverse-mixed tubular reactor. In other alternative embodiments, the non-reverse-mixed tubular reactor comprises two or more single-screw or twin-screw extruders operating in tandem, each having an upstream extruder (including at least a mixing section) that feeds to one or more downstream extruders (where pulping may occur) in series. In yet another alternative embodiment, a progressive cavity pump constitutes all or part of the non-reverse-mixed tubular reactor, including at least a mixing section. For example, the progressive cavity pump may feed to one or more downstream static mixers, where pulping occurs in certain embodiments.

[0017] The polyurethane foam is compressed, degassed, combined with component ii (i.e., polyether polyol) and other optional components described below, and wetted by the action of a rotating screw in the mixing section. The steps of compression, degassing, combination, and wetting in the mixing section are carried out at temperatures of 10 to 300°C. When high temperatures are used in this step, the starting material is preferably heated to such a temperature in the mixing section of a non-reverse-mixing tubular reactor.

[0018] In some embodiments, the steps of compression, degassing, and combining, as well as wetting, are carried out at 180–300°C, preferably 180–250°C or 180–225°C. These higher temperatures are particularly preferred in embodiments in which the steps of pulverizing the reaction mixture and chemically decomposing the polyurethane foam to produce a polyol dispersion are carried out entirely or primarily in a non-reverse-mixed tubular reactor. Some chemical decomposition typically occurs in the mixing section of a non-reverse-mixed tubular reactor.

[0019] In an alternative embodiment, the steps of compressing, defoaming, combining, and wetting are performed at 10 to 200°C, 10 to 150°C, 20 to 150°C, 20 to 100°C, or 20 to 60°C. Such lower temperatures are particularly suitable in embodiments where the subsequent step of digesting the reaction mixture and chemically decomposing the polyurethane foam to produce a polyol dispersion is performed outside the non-backmixed tubular reactor. Surprisingly, a small amount of the chemical decomposition process occurs even when very low temperatures, for example 150°C or lower, even 60°C or lower, are used.

[0020] The gas removed from the starting polyurethane foam may, if desired, be discharged from the non-backmixed tubular reactor separately from the reaction mixture. A vent or other gas removal port may be provided for this purpose.

[0021] The reaction mixture obtained after the steps of compressing, defoaming, combining, and wetting is generally a viscous fluid or paste-like semi-solid material that requires further digestion, even if some digestion occurs during the steps of compressing, defoaming, combining, and wetting.

[0022] Thereafter, the reaction mixture is digested at a reaction temperature of 180 to 300°C, preferably 180 to 250°C or 180 to 225°C. This can be carried out in a non-backmixed tubular reactor or in other apparatus such as a tank reactor (e.g., a continuous stirred tank reactor (CSTR)). The digestion time can be, for example, from 2 minutes to 10 hours. A preferred digestion time is 10 to 120 minutes, preferably 20 to 60 minutes, when digestion is performed in a non-backmixed tubular reactor. Digestion in a tank reactor can be carried out over a period of, for example, 20 minutes to 5 hours.

[0023] The digestion step is preferably performed under mixing conditions.

[0024] When the digestion is carried out in a non-backmixing tubular reactor, the reaction mixture is continuously advanced to pass from the upstream mixing section where the compression, defoaming, combining, and wetting steps are performed, into the downstream section of the non-backmixing tubular reactor. The reaction mixture is maintained at the reaction temperature in the downstream section of the non-backmixing tubular reactor, which digests the reaction mixture and chemically decomposes the polyurethane foam to produce a polyol dispersion in the non-backmixing tubular reactor. When the downstream section of the tubular reaction is a single-screw or twin-screw extruder or a part thereof, mixing can be provided by the operation of the rotating screw. Static mixing elements can also provide mixing conditions within the downstream section of the non-backmixing tubular reactor.

[0025] In embodiments where the digestion step is performed outside the non-backmixing tubular reactor, for example in a tank reactor, the reactor is preferably agitated, such as by operation of an agitator, or an agitator combined with static mixing elements.

[0026] The non-backmixing tubular reactor may include a device for controlling the pressure within the reactor. An example of such a device is a back pressure regulator or valve attached to the outlet port, that is, the port for removing the product obtained in the process. The pressure in the non-backmixing tubular reactor can be maintained at a predetermined value by the operation of such a device. In some embodiments, a superatmospheric pressure sufficient to maintain the various components and reaction products in liquid or solid form is maintained within the non-backmixing tubular reactor during the process.

[0027] During the pulping process, the polyurethane foam is converted into a polyol dispersion by reaction with polyols and other materials that, if present, may be added to the mixing area of ​​a non-reverse-mixed tubular reactor as one of the starting components, and / or may be added later during or before the pulping process. The dispersion comprises a liquid phase containing one or more polyols and a solid phase dispersed in the liquid phase. The polyols in the liquid phase typically include a portion of the polyol used as a starting material, as well as polyols produced by the decomposition of the polyurethane foam. The solid phase typically includes solid decomposition products produced in the pulping process. The polyol dispersion may have a hydroxyl value of, for example, 20 to 300 mg KOH / g, as measured according to ASTM D6342-22.

[0028] The pulverized product is cooled to 20-30°C from the reaction temperature. In a third aspect of the present invention, this cooling is performed after the polyol dispersion has been removed from the non-reverse-mixed tubular reactor and without refrigeration. "Without refrigeration" means that while the polyol dispersion is cooled to 20-30°C from the reaction temperature, the polyol dispersion does not come into direct or indirect contact with a fluid coolant having a temperature below 20°C, or with a cooled surface having a temperature below 20°C. Cooling in other aspects may be similarly performed without refrigeration.

[0029] The starting polyurethane foam may be flexible, semi-flexible, or rigid. The foam is characterized by having urethane groups and may contain other groups produced in various reactions of isocyanate groups, such as urea, isocyanurate, biuret, allophanate, carbodiimide, and similar groups. The foam may have open cells, closed cells, or any combination of both. The foam may be thermoplastic, but is typically crosslinked. Preferred foams are reaction products of components comprising at least one polyisocyanate and at least one polyether polyol, particularly at least one polyether polyol having a weight-average molecular weight of 400 to 8,000 g / mol (measured by size exclusion chromatography against a polyether standard) and 2 to 4 hydroxyl groups per molecule.

[0030] The starting polyurethane foam is most preferably waste foam, i.e., used waste and / or scrap or other waste from foam manufacturing or secondary processing processes. Specific used waste foams include foams recovered from bedding products such as mattresses and pillows, and / or seat cushions such as furniture cushions and car seats. Another preferred starting polyurethane foam is rigid foam from used waste recovered from electrical appliances, insulation panels, and the like.

[0031] The polyurethane foam may be shredded, crushed, or otherwise ground into small pieces to facilitate its supply to a non-reverse-mixing tubular reactor.

[0032] The polyol continuously supplied to the mixing region of the non-reverse-mixing tubular reactor in the first aspect of the present invention comprises at least one polyether polyol having a weight-average molecular weight of 400 to 8,000 g / mol, particularly at least 1,000 g / mol or at least 1,500 g / mol, preferably up to 6,000 g / mol. The polyether polyol may be one or more polymers of, for example, ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, or tetrahydrofuran. A preferred polyether polyol is a random and / or block copolymer of 60 to 95% by weight of 1,2-propylene oxide and 5 to 40% of ethylene oxide.

[0033] Such polyether polyols are preferably all or part of the polyol component supplied to the mixing region of the non-reverse mixing tube in other embodiments of the present invention. At least 50 parts by weight, at least 100 parts by weight, or at least 150 parts by weight, and up to 500 parts by weight, up to 300 parts by weight, or up to 200 parts by weight of polyether polyol per 100 parts by weight of polyurethane foam can be supplied to the mixing region.

[0034] In other embodiments of the present invention, the polyol may instead or in addition include a hydroxyl equivalent up to 75 g / equivalent, preferably up to 70 g / equivalent (measured by obtaining the hydroxyl value according to ASTM D6342-22 and converting the hydroxyl value to equivalent using the relationship equivalent = 56,100 / hydroxyl value), and a low equivalent polyol having 2 to 4 hydroxyl groups per molecule. Examples of such low molecular weight polyols include 1,2-ethanediol, diethylene glycol, 1,3-propanediol, dipropylene glycol, tripylene glycol, 1,4-butanediol, glycerin, dimethylolpropane, dimethylolethane, trimethylolpropane, trimethylolethane, etc. Such low equivalent polyols may also be components in the first embodiment of the present invention. In embodiments of the present invention in which the polyol comprises a polyether polyol having a molecular weight of 400 to 8,000 g / mol, a suitable amount of low equivalent polyol (if used) is at least 0.1 parts by weight, at least 0.25 parts by weight, or at least 0.5 parts by weight per 100 parts by weight of polyurethane foam, for example, up to 5 parts by weight, up to 10 parts by weight, or up to 5 parts by weight. In embodiments of the present invention in which a polyether polyol having a molecular weight of 400 to 8,000 g / mol is not used, a suitable amount of low equivalent polyol is at least 1 part by weight or at least 2 parts by weight, and up to 25 parts by weight, up to 15 parts by weight, or up to 10 parts by weight per 100 parts by weight of polyurethane foam.

[0035] The entire or partial pulverization process can be carried out in the presence of additional materials that perform useful functions. These include dicarboxylic acids or their anhydrides, such as one or more of the following: phthalic acid, phthalic anhydride, terephthalic acid, terephthalic anhydride, maleic acid, maleic anhydride, adipic acid, adipic anhydride, glutaric acid, glutaric anhydride, succinic acid, succinic anhydride, hydrogenated phthalic acid, hydrogenated phthalic anhydride, hydrogenated terephthalic acid, and hydrogenated terephthalic anhydride. In some embodiments, the dicarboxylic acid or anhydride is continuously supplied to the mixing region of a non-reverse-mixed tubular reactor and is therefore present during the compression, defoaming, combination, and wetting processes. In some embodiments, the solid dicarboxylic acid or anhydride can be melted in such a mixing region. In other embodiments, the dicarboxylic acid or anhydride is added to the downstream section of the non-reverse-mixed tubular reactor and / or tank reactor where the pulverization process takes place, after the compression, defoaming, combination, and wetting processes are completed.

[0036] Preferred amounts of dicarboxylic acid or anhydride, when used, are at least 1 part by weight, at least 5 parts by weight, or at least 10 parts by weight, and up to 50 parts by weight, up to 30 parts by weight, or up to 25 parts by weight per 100 parts by weight of polyurethane foam.

[0037] Another useful additional material is free radical initiators. Examples of these include hydrogen peroxides, t-butyl hydroperoxide, t-amyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, acetyl peroxide, benzoyl peroxide, t-butyl perbenzoic acid, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, acylalkylsulfonyl peroxides, dialkylperoxydicarbonates, diperoxyketals, ketone peroxides, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylpentanenitrile), 4,4'-azobis(4-cyanovaleric acid), 1,1'-azobis(cyclohexanecarbonitride), various tetrazines, and various persulfate compounds, such as potassium persulfate. Hydrogen peroxide is particularly useful. Like dicarboxylic acids or anhydrides, free radical initiators may be continuously supplied to the mixing region of a non-reverse-mixed tubular reactor and, in such cases, present during the compression, defoaming, combination, and wetting processes. Alternatively, free radical initiators are added to the downstream section of the non-reverse-mixed tubular reactor and / or to the tank reactor where the pulping process takes place, after the compression, defoaming, combination, and wetting processes are completed. Preferred amounts of free radical initiators, if used, are at least 0.1 parts by weight or at least 1 part by weight, and up to 20 parts by weight, up to 10 parts by weight, or up to 5 parts by weight per 100 parts by weight of polyurethane foam.

[0038] In a particular embodiment of the present invention, a starting polyurethane foam and a polyether polyol having a weight-average molecular weight of 400 to 8,000 are continuously supplied to the mixing zone of a non-reverse-mixed tubular reactor, where the foam is compressed, degassed, combined with the polyether polyol, and wetted with the polyether polyol to form a reaction mixture at a temperature of 180 to 300°C, preferably 180 to 250°C or 180 to 225°C. The reaction mixture is continuously advanced and passed from the mixing section to the downstream section of the non-reverse-mixed tubular reactor, where further materials comprising one or more of a dicarboxylic acid or anhydride, a low equivalent polyol, and a free radical initiator are combined with the reaction mixture. The reaction mixture is pulverized to chemically decompose the polyurethane foam and produce a polyol dispersion in the non-reverse-mixed tubular reactor.

[0039] In another specific embodiment of the present invention, a starting polyurethane foam, a polyether polyol having a weight-average molecular weight of 400 to 8,000, and one or more further materials comprising one or more dicarboxylic acids or anhydrides, low equivalent polyols, and free radical initiators are continuously supplied to the mixing zone of a non-reverse-mixed tubular reactor, where the foam is compressed and degassed, combined with the polyether polyol, and wetted with the polyether polyol to form a reaction mixture at a temperature of 180 to 300°C, preferably 180 to 250°C or 180 to 225°C, where the reaction mixture is continuously advanced and passed from the mixing section to the downstream section of the non-reverse-mixed tubular reactor, where the reaction mixture is pulverized to chemically decompose the polyurethane foam and produce a polyol dispersion in the non-reverse-mixed tubular reactor.

[0040] In another specific embodiment of the present invention, a starting polyurethane foam and a polyether polyol having a weight-average molecular weight of 400 to 8,000 are continuously supplied to the mixing zone of a non-reverse-mixed tubular reactor, where the foam is compressed, degassed, combined with the polyether polyol, and wetted with the polyether polyol to form a reaction mixture at a temperature of 10 to 200°C, preferably 10 to 150°C, 20 to 150°C, 20 to 100°C, or 20 to 60°C, where the reaction mixture is continuously advanced from the mixing section into a tank reactor, where further materials comprising one or more dicarboxylic acids or anhydrides, low equivalent polyols, and free radical initiators are combined with the reaction mixture, and the reaction mixture is pulverized at a temperature of 180 to 300°C to chemically decompose the polyurethane foam in the tank reactor to produce a polyol dispersion.

[0041] In yet another specific embodiment of the present invention, a starting polyurethane foam, a polyether polyol having a weight-average molecular weight of 400 to 8,000, and one or more further materials comprising one or more dicarboxylic acids or anhydrides, low equivalent polyols, and free radical initiators are continuously supplied to the mixing zone of a non-reverse-mixed tubular reactor, where the foam is compressed and degassed, combined with the polyether polyol, and wetted with the polyether polyol to form a reaction mixture at a temperature of 10 to 200°C, preferably 10 to 150°C, 20 to 150°C, 20 to 100°C, or 20 to 60°C, where the reaction mixture is continuously advanced from the mixing section to a tank reactor, where the reaction mixture is pulverized at a temperature of 180 to 300°C to chemically decompose the polyurethane foam in the tank reactor and produce a polyol dispersion.

[0042] Polyol dispersions produced by any of the processes of the present invention are useful for producing various types of polyurethanes, particularly rigid, semi-rigid, and / or flexible polyurethane foams, by reaction with polyisocyanates. Generally, a reaction mixture is formed by combining the polyol dispersion and polyisocyanate, and then cured to form polyurethane. Curing is typically spontaneous, even when the polyol dispersion and polyisocyanate are combined at approximately room temperature. However, the curing rate may be adjusted using a catalyst and / or a higher curing temperature, if desired. Curing may be carried out in a mold. The polyurethane foam can optionally be produced in a free-rise process, in which the foam formulation is distributed into an open trough or box and allowed to rise without vertical constraints. Various other components may be present in the reaction mixture, for example, A) Additional polyols such as polyethers and / or polyester polyols having a hydroxyl value of 375 mg KOH / g or less and 1 to 8 hydroxyl groups in one molecule. B) Short-chain polyols having 2 to 4 hydroxyl groups in one molecule and a hydroxyl value of 376 to 1870, C) Amino alcohols such as diethanolamine, monoethanolamine, and triethanolamine. D) Amine-terminated polyethers, E) Foaming agents including chemical foaming agents such as water and various types of physical foaming agents, F) Catalysts comprising a catalyst for the reaction of an isocyanate group with an alcohol, a catalyst for the reaction of an isocyanate group with water, and an isocyanate trimerization catalyst. G) Surfactants containing foam-stabilizing surfactants useful for producing polyurethane foams, H) Colorants, fillers, and other fine particles, I) Reinforced fibers, J) Biocides, disinfectants, antioxidants and other preservatives, K) Additives with a "cold feel," such as encapsulated phase change materials. It also includes other additives that may be useful in producing various types of polyurethane.

[0043] Suitable methods for producing various types of polyurethanes are described, for example, in particular, U.S. Patents 3,632,707, 4,350,778, 7,704,410, 4,970,243, 5,157,056, 5,582,840, and 6,005,016, and U.S. Publication No. 2020 / 0040153. Generally, the stabilized polyol dispersions of the present invention can be used to produce polyurethanes in the same general manner as conventional polyols with similar hydroxyl functional values ​​and equivalents. [Examples]

[0044] The following examples are provided to illustrate the present invention, but are not intended to limit the scope of the invention. All parts and percentages are by weight unless otherwise specified.

[0045] Examples 1-3 In Example 1, scrap rigid polyurethane foam powder is subjected to a hybrid glycolysis / acid digestion process using a Thermo Fisher Scientific Process 11 parallel-co-rotating intermesh 11 mm diameter twin-screw extruder equipped with a clamshell barrel. The extruder has an L / D ratio of 44 L / D and includes a 40 L / D barrel extension and a 4 L / D barrel extension. A MiniTwin MT0 gravimetric feeder supplies the starting material to the extruder's feed port.

[0046] In Example 2, a heated 21-element Kenics Koflo tube static mixer with an outer diameter of 0.375 inches and a length of 11 inches is connected to an extruder, and the contents of the extruder are fed into and passed through the static mixer by the forward movement of the extruder screw.

[0047] In Example 3, a Swagelok SS-18RF8 high-temperature back pressure valve is placed at the outlet of the static mixer.

[0048] In each of Examples 1 to 3, 46.8 parts of scrap foam powder are premixed with 41.6 parts of a trifunctional polyether polyol with a weight-average molecular weight of 3000, 10.4 parts of phthalic anhydride, and 1.2 parts of maleic anhydride. This premix is ​​continuously supplied to the extruder's supply port at a rate of 150 g / hour. The extruder temperature is set to 200°C. In Examples 2 and 3, the static mixer and back pressure valve (Example 3) are maintained at the same temperature. The screw is operated at 300 rpm. The material is continuously withdrawn through the outlet port of the apparatus.

[0049] In Example 1, the residence time was 3 minutes. A well-moistened, partially pulverized paste-like dispersion was produced. In Example 2, the residence time was approximately 8 minutes. Better mixing and additional reaction were observed, resulting in a softer, more uniform paste-like material. In Example 3, the residence time was approximately 12 minutes, and the product was significantly softer, indicating further pulverization of the starting PU foam.

[0050] Examples 4-8 The premix is ​​prepared by combining the components listed in Table 1.

[0051] [Table 1]

[0052] The premixes were processed through an extruder (Examples 4-6) or a tandem extruder / static mixer apparatus (Examples 7 and 8), as described for Examples 1-3. The extruder temperature (and static mixer temperature, if used) is shown in Table 2. In each case, the extruder screw was operated at 400 rpm. The feed rate was 300 g / hour, except for Example 8, in which case the feed rate was 150 g / hour only. The approximate residence times are shown in Table 2. The resulting paste-like product dispersion was dissolved in a suitable solvent, and the resulting solution was analyzed by proton NMR to estimate the amount of polyol, insoluble material, and the conversion rate of the starting polyurethane to a soluble depolymerization product. The results are shown in Table 2.

[0053] [Table 2]

[0054] As the data in Table 2 shows, a large proportion of the starting polyurethane foam is converted into soluble substances in an extruder or extruder / static mixer apparatus at low temperatures (180-200°C) and short residence times. The results of Example 4 are particularly noteworthy in that a simplified reaction mixture without hydrogen peroxide or dipropylene glycol is used. Hydrogen peroxide and dipropylene oxide are well known to have a facilitating effect on chemical decomposition reactions. The ability to achieve good conversion under mild conditions and short residence times in the absence of these materials is particularly noteworthy.

[0055] Examples 9 and 10 The premix is ​​prepared by combining the components listed in Table 3.

[0056] [Table 3]

[0057] The premix was processed through an extruder without a static mixer, as described for Examples 1-3. The extruder temperature was 135°C for Example 9 and room temperature for Example 10. In each case, the extruder screw was operated at 400 rpm and the feed rate was 300 g / hour. The approximate residence time was about 1.5 minutes. In each case, a thick paste-like product dispersion was obtained. Proton NMR for both Examples 9 and 10 showed a conversion rate of about 10-11% of the starting polyurethane foam, despite the low operating temperature.

[0058] Next, each of the paste-like extruded materials is further pulverized in a glass batch reactor to produce Examples 9A to 9D and 10A.

[0059] Example 9A was prepared by heating 100 parts of the extruded material from Example 9 to 200°C and combining it with 9 parts of phthalic anhydride. The resulting mixture was stirred for 2 hours while maintaining the temperature at 200°C to produce a thick yellowish-brown fluid dispersion. The conversion rate of the polyurethane foam was measured to be 37% using proton NMR.

[0060] Example 9B is prepared by heating 100 parts of the extruded material from Example 9 to 215°C and combining it with 9 parts phthalic anhydride and 2 parts hydrogen peroxide. The resulting mixture is stirred at 215°C for 1.5 hours, during which some maleic anhydride is added, and then heated at the same temperature for a further 30 minutes while continuing to stir. A dark brown fluid dispersion is obtained. The conversion rate of the polyurethane foam is 66%.

[0061] Example 9C is prepared by heating 100 parts of the extruded material from Example 9 to 200°C and combining it with 9 parts phthalic anhydride and 2 parts hydrogen peroxide. The resulting mixture is stirred at 200°C for 2.5 hours, during which time some maleic anhydride is added, and then the mixture is heated at the same temperature for a further 90 minutes while continuing to stir. A dark brown fluid dispersion is obtained. The conversion rate of the polyurethane foam is 55%.

[0062] Example 9C is prepared by combining 100 parts of the extruded material from Example 9 with 9 parts of phthalic anhydride and 2 parts of hydrogen peroxide at room temperature. The resulting mixture is heated to 200°C for 2.5 hours while stirring, at which point some maleic anhydride is added, and then heated at the same temperature for a further 90 minutes while continuing to stir. A dark brown fluid dispersion is obtained. The conversion rate of the polyurethane foam is 66%.

[0063] Example 10A was prepared by combining 100 parts of the extruded material from Example 10 with 2 parts of hydrogen peroxide at room temperature, heating the resulting mixture to 200°C for 2.5 hours, then adding some maleic anhydride, and heating at the same temperature for a further 90 minutes while continuing to stir. A dark brown fluid dispersion was obtained. The conversion rate of the polyurethane foam was 72%.

Claims

1. A process for producing a polyol dispersion from a polyurethane foam, a) A step of continuously supplying a component comprising (component i) a polyurethane foam and (component ii) a polyether polyol having a weight-average molecular weight of 400 to 8000 g / mol to a non-reverse-mixing tubular reactor having a rotating screw including a forward element, b) A step of compressing and degassing the polyurethane foam in the non-reverse-mixing tubular reactor at a temperature of 10 to 300°C by the action of the rotating screw, combining the compressed and degassed polyurethane foam with component ii and wetting it to form a reaction mixture, and then c) The process includes a step of pulverizing the reaction mixture at a reaction temperature of 150 to 300°C to chemically decompose the polyurethane foam and produce the polyol dispersion.

2. The process according to claim 1, wherein step c) is carried out by heating the reaction mixture to a reaction temperature of 150 to 300°C in the mixing section of the non-reverse-mixing tubular reactor, and while maintaining the reaction mixture at the reaction temperature in the downstream section of the non-reverse-mixing tubular reactor, continuously advancing and passing the reaction mixture through the downstream section of the non-reverse-mixing tubular reactor to pulverize the reaction mixture, chemically decompose the polyurethane foam, and produce the polyol dispersion in the non-reverse-mixing tubular reactor.

3. The process according to claim 1, wherein a back pressure regulator or valve is attached to the outlet end of the non-reverse mixing tubular reactor, and the superatmospheric pressure is sufficient to maintain the components and the polyol dispersion in liquid or solid form.

4. The process according to claim 2, further comprising step d) continuously removing the polyol dispersion from the outlet end of the non-reverse-mixing tubular reactor.

5. The process according to claim 1, wherein step c) is performed by removing the reaction mixture from the non-reverse-mixing tubular reactor and pulverizing the reaction mixture in a batch reactor.

6. The process according to any one of claims 1 to 5, wherein the temperature in step b) is 10 to 200°C.

7. The process according to claim 6, wherein the temperature in step b) is 10 to 150°C.

8. The process according to any one of claims 1 to 5, wherein the temperature in step b) is 180 to 300°C.

9. The process according to any one of claims 1 to 7, wherein the component further comprises a dicarboxylic acid or an anhydride.

10. The process according to claim 9, wherein the dicarboxylic acid or the anhydride is one or more of phthalic acid, phthalic anhydride, maleic acid, maleic anhydride, adipic acid, adipic anhydride, glutaric acid, glutaric anhydride, succinic acid, succinic anhydride, hydrogenated phthalic acid, hydrogenated phthalic anhydride, hydrogenated terephthalic acid, and hydrogenated terephthalic anhydride.

11. The process according to any one of claims 1 to 10, wherein the aforementioned component further comprises a peroxide.

12. The process according to any one of claims 1 to 11, wherein the component further comprises a polyol having up to 75 hydroxyl equivalents and 2 to 4 hydroxyl groups.

13. The process according to any one of claims 1 to 12, wherein the polyol polyether polyol having 2 to 4 hydroxyl groups and a weight-average molecular weight of 400 to 8,000 constitutes 40 to 70% by weight of the component and the polyurethane foam, and constitutes 25 to 60% by weight of the component.

14. A process for producing a polyol dispersion from a polyurethane foam, A step of continuously supplying a component comprising (component i) polyurethane foam, (component ii) polyol, and (component iii) dicarboxylic acid and / or dicarboxylic acid anhydride to a mixing section of a non-reverse-mixing tubular reactor, wherein the mixing section of the non-reverse-mixing tubular reactor has a rotating screw including a forward element, The steps include: compressing and degassing the polyurethane foam in the mixing section; wetting the compressed and degassed polyurethane foam in the mixing section with components ii and iii to form a reaction mixture; and heating the reaction mixture to a reaction temperature of 150 to 300°C. A step of maintaining the reaction mixture at the reaction temperature in the downstream section of the non-reverse-mixing tubular reactor, while continuously advancing and passing the reaction mixture from the mixing section into the downstream section of the non-reverse-mixing tubular reactor, thereby pulverizing the reaction mixture, chemically decomposing the polyurethane foam, and generating a polyol dispersion in the non-reverse-mixing tubular reactor, The process includes a step of continuously removing a polyol dispersion from the outlet end of a non-reverse-mixing tubular reactor.

15. A process for producing a polyol dispersion from a polyurethane foam, A step of continuously supplying a component comprising (component i) a polyurethane foam and (component ii) a polyol to a mixing section of a non-reverse-mixing tubular reactor, wherein the mixing section of the non-reverse-mixing tubular reactor has a rotating screw including a forward element, The steps include: compressing and degassing the polyurethane foam in the mixing section; wetting the compressed and degassed polyurethane foam in the mixing section with component ii to form a reaction mixture; and heating the reaction mixture to a reaction temperature of 150 to 300°C. A step of maintaining the reaction mixture at the reaction temperature in the downstream section of the non-reverse-mixing tubular reactor, while continuously advancing and passing the reaction mixture from the mixing section into the downstream section of the non-reverse-mixing tubular reactor, thereby pulverizing the reaction mixture, chemically decomposing the polyurethane foam, and generating a polyol dispersion in the non-reverse-mixing tubular reactor, The process includes continuously removing the polyol dispersion from the outlet end of the non-reverse-mixing tubular reactor and cooling the dispersion to a temperature of 20 to 30°C without applying refrigeration.

16. A process for producing a polyol dispersion from a polyurethane foam, A step of continuously supplying components (i) polyurethane foam and (ii) polyol to an extruder, wherein the extruder has a rotating screw including a forward element, The process involves compressing and degassing the polyurethane foam in the extruder, wetting the compressed and degassed polyurethane foam in the extruder with component ii to form a reaction mixture, and heating the reaction mixture to a reaction temperature of 150 to 300°C. A step of maintaining the reaction mixture at the reaction temperature in a static mixer, continuously advancing the reaction mixture from the extruder into the static mixer, pulverizing the reaction mixture in the static mixer, and chemically decomposing the polyurethane foam to produce a polyol dispersion, The process includes the step of continuously removing the polyol dispersion from the outlet end of the static mixer.

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