A modified polyol product and a method of making a modified polyol product

Abstract

The present invention discloses a modified polyol product and a method for manufacturing the modified polyol product, the modified polyol product is obtained by treating an initial polymer, the treatment includes the following steps: step A: carrying out a degradation reaction on the initial polymer with a degradation agent with active groups, breaking at least a part of the molecular chains of the initial polymer, and preparing a resin intermediate containing initial polymer molecular fragments and active groups; the initial polymer is a cured polyurethane, preferably a polyurethane waste, the degradation agent includes a combination of a polyol and an anhydride, and the resin intermediate is the modified polyol product. The method of the present invention does not have the step of adding water, and by adding a certain amount of an anhydride to the polyol and mixing, and then carrying out a degradation reaction with the polyurethane waste, or by adding a certain amount of an anhydride or an anhydride and polyol mixture after the degradation reaction of the polyol and the polyurethane waste, a modified polyol product with a low amine value can be efficiently obtained.

Description

Technical Field

[0001] This patent relates to the field of polymer materials technology, and specifically to a modified polyol product and a method for manufacturing the modified polyol product. Background Technology

[0002] The alcoholysis recycling of polyurethane solid materials, including polyurethane solid waste, scraps generated during polyurethane product manufacturing, decommissioned polyurethane materials (rigid foam for refrigerator containers, soft foam for mattresses and sofas, shoe sole materials, polyurethane elastomers, semi-rigid polyurethane foam, polyurethane adhesives, etc.), and polyurethane composite materials (window frames, beams, solar panel frames, sleepers, cable boxes, battery casings, brackets, etc.), will produce some side reactions during the alcoholysis recycling process, resulting in modified polyol products with high amine values. This is mainly because the alcoholysis process generates large amounts of aromatic amines (in polyurethane materials based on aromatic isocyanates such as MDI and TDI) or aliphatic amines (in polyurethane materials based on aliphatic isocyanates such as IPDI and HDI). These substances are toxic, and direct contact between polyurethane containing them and the human body can be harmful. Furthermore, if the modified polyol products contain excessive amounts of these substances (i.e., excessively high amine values), the reaction with isocyanates to produce cured polyurethane will be too rapid, significantly shortening the process time or even making the process impossible. Reducing the amine value of the degraded polyols can improve the safety of the modified polyurethane and extend the process time for preparing cured polyurethane. However, how to simply and efficiently reduce the content of these amines in the modified polyol products has always been a significant challenge in the chemical degradation and recycling of polyurethane solid waste. Summary of the Invention

[0003] This invention provides a modified polyol product and a method for manufacturing the modified polyol product, which can solve the problem of how to simply and efficiently reduce the content of amines in polyol products and further optimize the degradation process steps.

[0004] First, this invention provides a modified polyol product containing urethane molecule fragments and hydroxyl groups. According to ASTM E1899-2016, the hydroxyl value of the modified polyol product is 5–800 mg KOH / g, and the amine value is 0–20, 20–30, 30–40, 40–50, 50–60, 60–80, 80–100, 100–120, 120–150, 150–180, 180–230, 230–280, or 280–500 mg KOH / g.

[0005] Preferably, the modified polyol product has a hydroxyl value of 10–800 mg KOH / g, with a hydroxyl value greater than 10; further, the modified polyol product has an amine value of 0–150 mg KOH / g.

[0006] The higher the hydroxyl value of the modified polyol product, the greater its activity and the lower its average number-average molecular weight (Mn), resulting in a higher crosslinking density of the cured polyurethane, and vice versa. When the hydroxyl value exceeds 800 mg KOH / g, the low average number-average molecular weight (Mn) leads to an excessively low molecular weight of the modified resin obtained through further grafting, resulting in excessively brittle cured polyurethane after further reaction with the curing agent. Alternatively, the modified polyol product may react directly with the curing agent to produce excessively brittle cured polyurethane. If the hydroxyl value is below 5 mg KOH / g, the insufficient number of active hydroxyl groups results in insufficient activity in reacting with the grafting agent or curing agent, preventing the modified polyol from fully reacting with the agent to allow its molecular chain segment characteristics to contribute to the performance improvement of the cured polyurethane.

[0007] When the curing agent is a compound containing isocyanate, the higher the amine value of the polyol product, the faster the reaction rate between the polyol and isocyanate. Modified polyol products with different amine values ​​have different reaction rates with isocyanate. If the amine value is greater than 150 mg KOH / g, the reaction with the reactant containing isocyanate will be too fast, which will increase the requirements for process operation time and may result in insufficient process operation time. Modified polyols with an amine value of 180–500 mg KOH / g cannot react directly with isocyanates to produce cured polyurethane because the reaction rate is too fast to operate. They can only be added in small proportions to polyols with low amine values. Modified polyols with an amine value of 80–180 mg KOH / g cannot react directly with isocyanates to produce cured polyurethane, but can be added in larger proportions to polyols with low amine values. Modified polyols with an amine value of 40–80 mg KOH / g can react directly with isocyanates to produce cured polyurethane, but can only be used in rapid curing polyurethane production processes. Modified polyols with an amine value of 20–40 mg KOH / g can react directly with isocyanates to produce cured polyurethane and can be used in molding curing polyurethane production processes. Modified polyols with an amine value of 0–20 mg KOH / g can react directly with isocyanates to produce cured polyurethane and can be used in slow curing polyurethane production processes.

[0008] Furthermore, the modified polyol product contains R1-NH-CO-R2 amide groups. These amide groups form strongly polar bonds, which is beneficial for improving the mechanical properties of the cured polyurethane obtained by reacting the modified polyol product with the curing agent.

[0009] Furthermore, according to GB / T 6040-2019 infrared spectroscopy testing, the absolute threshold of the infrared spectroscopy test is 0.001, the sensitivity is 50, and the difference between the absorbance intensity at the top and bottom of the measured infrared absorption peak is not less than 0.03. The modified polyol product measured according to this standard has an absorption intensity of 1680 cm⁻¹. -1 ~1780cm -1 1480cm -1 ~1570cm -1 and 1100cm -1 ~1210cm -1 It has an infrared absorption peak in the wavenumber range, and at 1680 cm⁻¹ -1 ~1780cm -1 The peak height of the infrared absorption peak in the wavenumber range is not less than 1480 cm⁻¹. -1 ~1570cm -1 The infrared absorption peaks account for 70% of the peak height in the wavenumber range, and infrared absorption peaks are also present in the wavenumber range of 1090–1210 cm⁻¹. More preferably, infrared absorption peaks are present in the wavenumber range of 1110–1200 cm⁻¹. Most preferably, infrared absorption peaks are present in the wavenumber range of 1100 cm⁻¹. -1 ~1210cm -1 The presence of infrared absorption peaks in the wavenumber range, combined with other infrared spectral features, indicates that the modified polyol product contains R1-NH-CO-R2 groups. In this invention, preferably, the peak value is 1680 cm⁻¹. -1 ~1780cm -1 The characteristic peak absorption intensity within the range and 1480 cm⁻¹ -1 ~1570cm -1 The characteristic peak absorbance intensity ratio (i.e. height ratio) within the range is in the range of 0.7 / 1-2.5 / 1. This characteristic can indicate that the modified polyol product has a low proportion of phenylamino groups generated by the degradation of urethane functional groups, and has the characteristic of low amine value.

[0010] Furthermore, the peak distribution regions of the number-average molecular weight Mn of the modified polyol product, measured by both RID and VWD (254nm) detectors, include 150–200; 200–350; 350–700; 700–1000; 700–1000; 1000–1800; 1800–3000; 3000–5000; 5000–10000; 10000–30000; and 30000–60000 g / mol. Preferably, the area ratio of Mn greater than 30000 g / mol measured by the aforementioned method is no more than 20%. This results in a modified polyol product with a smaller molecular weight, higher reactivity, and distribution across various molecular weight regions, leading to better compatibility when mixed with other polyols.

[0011] Furthermore, the modified polyol product has a viscosity (at 25°C, all viscosities below are at 25°C) greater than 20000 mPa·s or is a solid. The modified polyol product is in one or more of the following forms: paste, granules, flakes, powder, or strips, with the particle size of the powder not less than 50 μm. Compared to the activated polyurethane micropowder disclosed in CN 113773549 A, which has a particle size of less than 40 μm, the modified polyol product is easier to store, package, and transport. Since hydroxyl groups are hygroscopic, excessively fine particles will absorb moisture and affect further use. At the same time, excessively fine dust will cause environmental pollution and affect the health of operators.

[0012] Furthermore, the modified polyol product is soluble in a solvent and can pass through a sieve of 50-800 mesh. The solvent includes one or more of methanol, ethanol, isopropanol, polyol, methyl ethyl ketone, acetone, cyclohexanone, DMF, DMSO, DMAC, and toluene. The temperature at which the modified polyol product dissolves in the solvent is 40-150℃. This step yields a modified polyol product solution with a particle size of 40-270 μm. Within this particle size range, the modified polyol product exhibits good compatibility with the solvent.

[0013] Preferably, the modified polyol product is dissolved in polyol and filtered through sieves of different mesh sizes to obtain graded polyol blends. The modified polyol product with small particle size and the polyol solution are clear and can be used as a refined modified polyol blend. The modified polyol product with large particle size and the polyol solution are suspensions with slightly inferior performance, but can still be used in specific applications.

[0014] All polyols described in this invention are hydroxyl-containing compounds with a hydroxyl functionality greater than 1.

[0015] Furthermore, the modified polyol product is obtained by the following steps:

[0016] Step A: The initial polymer is subjected to a degradation reaction with a degrading agent containing active groups to break at least a portion of the molecular chain of the initial polymer, thereby obtaining a modified polyol product containing molecular fragments of the initial polymer and active groups.

[0017] The initial polymer includes thermoplastic polymers with linear or branched molecular structures or thermosetting polymers with cross-linked network molecular structures, and the molecular weight of the initial polymer is not less than 10,000 g / mol.

[0018] Initially, the polyurethane was polyurethane waste.

[0019] The degrading agent includes one or more of the following: polyols, acid anhydrides, compounds containing carboxyl groups, and compounds containing both carboxyl and hydroxyl groups. The carboxyl-containing compounds described in this invention can be single compounds or reaction products of acid anhydrides reacting with compounds containing hydroxyl or amine groups; they can be synthetic or natural products. When the degrading agent includes polyols and acid anhydrides, the polyol reacts completely or partially with the acid anhydride to form a composite degrading agent containing at least one or more of the following: polyols, acid anhydrides, carboxyl-containing compounds, and compounds containing both carboxyl and hydroxyl groups.

[0020] The degradation reaction times are 4–30 minutes, 0.5–2 hours, 2–3 hours, 3–6 hours, 6–12 hours, and 12–24 hours.

[0021] The modified polyol product described in this invention is a resin intermediate. The modified polyol product used as a resin intermediate in this invention can either react with a grafting agent to generate a modified resin, which is then reacted with a curing agent to produce a cured polyurethane, or it can directly react with a curing agent to produce a cured polyurethane.

[0022] The degradation reaction time is related to the degradation reaction temperature, degradation mixing process, and the selection of degradation agent and catalyst. Under the premise of ensuring the quality and yield of the modified polyol product, the shorter the degradation reaction time, the lower the energy consumption and the lower the cost.

[0023] Furthermore, the degradation reaction does not involve the addition of water, hydrogen peroxide, or free radical initiators. In this invention, "not involving the addition of water" means that no additional free water is added during the reaction, nor is moisture added to the normally dry polyurethane solid waste and chemical raw materials. Typically, polyurethane solid waste and chemical raw materials with a moisture content of less than 10 wt% are used, preferably less than 5 wt%, more preferably less than 2 wt%. Optionally, the polyurethane waste is dried to reduce its moisture content.

[0024] In existing technologies, water, hydrogen peroxide, or free radical initiators are typically added to the mixture of polyol and acid anhydride to promote the degradation efficiency of polyurethane waste. Even so, the degradation time is still as long as 13 hours or more. This invention surprisingly discovers that, using the above method, even without adding water, hydrogen peroxide, or free radical initiators, it is still possible to obtain modified polyol products with low amine values, and the time can be shortened. This not only reduces raw material costs but also improves production safety and efficiency.

[0025] Furthermore, the acid anhydride or carboxyl-containing compound preferably contains a double bond, with maleic anhydride being a preferred example. This allows the modified polyol molecule to contain double bonds, which can be used to increase the crosslinking density and improve mechanical properties through free radical initiation.

[0026] Furthermore, the modified polyol product contains an initial polyurethane component of not less than 25% by weight, preferably not less than 40% by weight, more preferably not less than 50% by weight, more preferably not less than 60% by weight, and even more preferably not less than 70% by weight. This reduces costs on the one hand, maximizes the utilization rate of solid waste on the other, and preserves as many molecular fragments and properties of the initial polymer as possible.

[0027] Furthermore, the present invention provides a modified curing polyurethane, which is prepared by reacting a modified polyol product of any of the above-mentioned schemes with a curing agent.

[0028] Furthermore, in step A, the degrading agent simultaneously carries both active groups and chain-extending groups; since the degrading agent simultaneously carries both active groups and chain-extending groups, any of the above-mentioned modified polyol products carries chain-extending groups, so they can be used as resin intermediates to react with grafting agents to generate cured polyurethane, or directly used as modified resins to react with curing agents through their chain-extending groups to generate cured polyurethane.

[0029] Furthermore, the chain-extending group includes hydroxyl groups.

[0030] Furthermore, the curing agent contains reactive functional groups capable of reacting with chain-extending groups, including one or more combinations of isocyanate groups, acid anhydrides, carboxyl groups, epoxy groups, amine groups, amide groups, or aldehydes. Preferably, the curing agent contains isocyanate groups, so that the modified polyol product can react with the curing agent to generate cured polyurethane, which can then be used as initial polyurethane to degrade into modified polyol products using the method of the present invention, thus achieving the recycling of polyurethane.

[0031] In existing technologies, the recycling of polyurethane solid waste can be divided into physical and chemical methods. The most commonly used chemical technique involves alcoholysis of solid polyurethane to obtain the released polyols, which are then blended with conventional polyols to prepare new polyurethane products. However, the polyols obtained from this alcoholysis method typically contain amino groups. These amino groups are generally undesirable byproducts in industry, primarily because most of them are aromatic amines, which have a certain degree of toxicity. Furthermore, these amines can catalyze polyurethane reactions, interfering with normal polyurethane formulation adjustments and product manufacturing. Therefore, reducing the amine value of these modified polyol products from polyurethane alcoholysis has always been a challenging problem for industry. A common method is to separate and purify these polyols to minimize the amine content, but this method adds an extra purification step, increasing the cost and reducing the yield of the polyurethane solid waste alcoholysis process. The purification process also generates additional waste liquid and gas, as well as energy consumption.

[0032] Some literature reports the use of epoxides to further process alcoholysis products, converting aromatic amines into secondary amines through ring-opening reactions between aromatic amines and epoxides. While this method reduces the toxicity of aromatic amines, the catalytic activity of the amines remains a problem. Other literature reports that during the alcoholysis of polyurethane foam, sequentially adding polyols, acid anhydrides (or acids), water or hydrogen peroxide or free radical initiators, followed by heating for a period of time, and then sequentially adding solid polyurethane, water, acid anhydrides, water, and alcohols, can effectively reduce the amine value of the polyol products obtained from alcoholysis. However, this method involves many steps, is time-consuming, and results in products with relatively large particle sizes. The method of this invention solves this problem simply and efficiently.

[0033] The present invention also provides a method for manufacturing modified polyol products, comprising the following steps:

[0034] Step A: The initial polymer is subjected to a degradation reaction with a degrading agent containing active groups to break at least a portion of the molecular chain of the initial polymer, thereby obtaining a modified polyol product containing molecular fragments of the initial polymer and a modified polyol product containing active groups.

[0035] The initial polymer includes thermoplastic polymers with linear or branched molecular structures or thermosetting polymers with cross-linked network molecular structures, and the molecular weight of the initial polymer is not less than 10,000 g / mol.

[0036] Initially, the polyurethane was polyurethane waste.

[0037] Degrading agents include one or more of the following: polyols, acid anhydrides, compounds containing carboxyl groups, compounds containing hydroxyl groups, and compounds containing both carboxyl and hydroxyl groups.

[0038] The degradation reaction does not involve the addition of water, hydrogen peroxide, or free radical initiators;

[0039] The degradation reaction times are 4–30 minutes, 0.5–2 hours, 2–3 hours, 3–6 hours, 6–12 hours, and 12–24 hours.

[0040] The degradation reaction temperatures are 110–150℃, 150–170℃, 170–180℃, 180–200℃, 200–220℃, and 220–250℃.

[0041] Furthermore, the degrading agent is prepared by reacting polyols and acid anhydrides, including a mixture of unreacted or partially reacted polyols and acid anhydrides, or a product of complete reaction of polyols and acid anhydrides.

[0042] Furthermore, the polyol is a diol. The reaction of diols with acid anhydrides can form compounds with monocarboxyl and monohydroxy groups, which reduces the risk of cross-linking with degradation products, allows the carboxyl group to react with the amine group to block the amine group and reduce the amine value, and allows the degradation products to be attached with hydroxyl chain extenders so that they can react with curing agents to cure.

[0043] Furthermore, the degradation reaction does not involve the addition of water, hydrogen peroxide, or free radical initiators.

[0044] Furthermore, the acid anhydride or compound containing a carboxyl group preferably contains a double bond, and the acid anhydride preferably includes maleic anhydride.

[0045] Furthermore, step A includes:

[0046] Step A1: Mix acid anhydride and polyol to obtain a degradation agent. The reaction does not involve the addition of water. Step B1: Add polyurethane to the degradation agent obtained in Step A1, heat and mix to allow the polyurethane to undergo a degradation reaction, and obtain a reaction mixture containing modified polyol products. The degradation reaction does not involve the addition of water, hydrogen peroxide, or free radical initiators.

[0047] Furthermore, step C further includes:

[0048] Step C1: Filter the reaction mixture obtained in step B1 to obtain a filtrate and a filter cake containing the modified polyol product. The filter cake can be used as a crude modified polyol product with active groups.

[0049] Optionally, the filtrate can be distilled to obtain the modified polyol product, or used directly as the modified polyol product.

[0050] Furthermore, in step A1, the temperature of the mixed reaction is 30℃~140℃; the time of the mixed reaction is 30~480min; a temperature below 30℃ will result in low efficiency in reducing the amine value, and a temperature above 140℃ will result in side reactions of the acid anhydride, thus reducing the efficiency of acid anhydride amine removal.

[0051] In step B1, the degradation reaction temperature is 110–250°C; the degradation reaction time is 30 minutes–24 hours. A degradation temperature below 110°C will result in an excessively long degradation time, while a temperature above 250°C will cause a large number of side reactions, reducing the molecular weight of the modified polyol product and causing a decline in the performance and processability of the cured polyurethane.

[0052] In step C1, the reaction mixture is cooled to 100–180°C. If the temperature is too low, the viscosity of the reaction mixture increases, making it difficult to filter; if the temperature is too high, new side reactions will occur, generating new byproducts.

[0053] Furthermore, the modified polyol products contain amide groups.

[0054] As another embodiment of the method disclosed in this invention, the polyurethane is first subjected to a degradation reaction with a polyol, and then an acid anhydride or carboxylic acid is added to remove the amine value. Specifically, step A includes:

[0055] Step A2: Add the polyurethane to the degradation agent, heat and stir to allow the polyurethane to undergo the degradation reaction, and obtain a reaction mixture. The degradation reaction does not involve the addition of water, hydrogen peroxide or free radical initiator.

[0056] Step B2: The acid anhydride and / or carboxyl-containing compound are mixed with the reaction mixture obtained in step A2, wherein the reaction does not involve the addition of water, hydrogen peroxide or free radical initiator.

[0057] Step A further includes:

[0058] Step C2: Cool the reaction mixture obtained in step B2 and filter it to obtain a filtrate and a filter cake containing the modified polyol product. The filter cake can be used as a crude modified polyol product with active groups.

[0059] Optionally, the filtrate can be distilled to obtain the modified polyol product, or used directly as the modified polyol product;

[0060] In step A2, the temperature of the degradation reaction is 110–250°C; the time of the degradation reaction is 30 minutes–24 hours.

[0061] In step B2, the temperature of the degradation reaction is 30℃~180℃, and the time of the mixing reaction is 30~480min.

[0062] The present invention also provides the application of the modified polyol product obtained by any one of the above technical solutions in the preparation of rigid polyurethane foam, which can improve its compressive strength.

[0063] The present invention also provides the application of the modified polyol product obtained by any one of the above technical solutions in the preparation of polyurethane flexible foam, which can improve its tear strength.

[0064] The present invention also provides the application of the modified polyol product obtained by any one of the above technical solutions in the preparation of polyurethane elastomers, which can improve their tensile strength.

[0065] The present invention also includes the following aspects:

[0066] In a first aspect, the present invention provides a method for manufacturing a modified polymer, wherein the modified polymer is obtained by treating an initial polymer, the treatment comprising the following steps:

[0067] Step A: The initial polymer reacts with a degrading agent containing active groups to break at least a portion of the molecular chain of the initial polymer, forming a resin intermediate containing molecular chain fragments of the initial polymer with active groups;

[0068] Step C: React the resin intermediate with a grafting agent containing grafting groups to prepare a modified resin containing initial polymer molecular chain segments with chain-extending groups. The chain-extending groups can be on the degradation agent molecules or on the grafting agent molecules.

[0069] Step F: Then, the modified resin is mixed with the curing agent. The initial polymer molecular chain segments in the modified resin are reconnected into new macromolecules through the reaction between the curing agent and the chain extension groups or through the reaction between the chain extension groups initiated by the curing agent, thus producing the modified polymer.

[0070] Secondly, the present invention also provides another method for manufacturing a modified polymer, wherein the modified polymer is obtained by treating an initial polymer, the treatment comprising the following steps:

[0071] Step C: First, react the initial polymer with a grafting agent containing chain extender groups to break the polymer molecular chain and form a modified resin containing the initial polymer molecular chain fragments with chain extender groups.

[0072] Step F: The modified resin is mixed with a curing agent. The initial polymer molecular chain segments in the modified resin are reconnected into new macromolecules through the reaction between the curing agent and the chain extension groups or through the reaction between the chain extension groups initiated by the curing agent, thereby obtaining the modified polymer.

[0073] This invention also claims a method for manufacturing a modified polymer as a resin intermediate, the modified polymer being obtained from an initial polymer through a treatment comprising the following steps:

[0074] A: The initial polymer is subjected to a degradation reaction with a degrading agent containing active groups to break at least a portion of the molecular chain of the initial polymer, thereby obtaining a resin intermediate containing molecular chain fragments of the initial polymer containing active groups.

[0075] The initial polymer includes thermoplastic polymers with linear or branched molecular structures or thermosetting polymers with cross-linked network molecular structures, and the molecular weight of the initial polymer is not less than 10,000 g / mol.

[0076] Furthermore, the thermosetting polymer includes polyurethane. Preferably, the initial polymer molecular chain has severable groups, and in step A, the main molecular chain of the initial polymer breaks at the severable groups, which include one or more combinations of -N(H)n-, -NH-(CO)-O-, and -HN-(CO)-NH-. Preferably, the initial polymer molecular chain has side groups that do not include hydrogen atoms, and these side groups react cooperatively with the degrading agent to facilitate the breaking of the initial polymer molecule. The degradation reaction in step A includes alcoholysis.

[0077] Preferably, the degradation reaction comprises the following reactions:

[0078] R1-A-(R2S(2S)-B2

[0079] Wherein, -R1-A-(R2S)- is the initial polymer, A is the chain-breaking group, S is the side group, R3-B- is the degrading agent, and -B- is the active group of the degrading agent; R1-(A1)-R3-B1- and (R2S)-B2- are the initial polymer molecular fragments formed after the initial polymer chain is broken, -A1- is the group formed after the chain-breaking group A is degraded, and -B1- and -B2- are the active groups formed at both ends of the molecular chain by the active end group B of the degrading agent. The active groups A1, B1, or B2 participate in the subsequent reactions.

[0080] Preferably, the weight ratio of the initial polymer to the degrading agent is 1:0.1-0.4, 1:0.4-2, 1:2-5, or 1:5-15.

[0081] Based on the problems existing in the current polyurethane manufacturing methods, the present invention proposes that, in step A, the initial polymer is a thermoplastic polyurethane (TPU) having a linear or branched molecular structure and, or a thermosetting polyurethane having a cross-linked network molecular structure; wherein, the initial polymer molecular chain has chain-breaking groups, and in step A, the initial polymer is reacted with a degradation agent to break the molecular weight of the initial polymer at the chain-breaking groups.

[0082] Furthermore, in step A, the initial polyurethane is mixed with a degradation agent to carry out a degradation reaction, thereby obtaining a resin intermediate containing molecular fragments and active groups of the initial polyurethane.

[0083] Furthermore, the chain-severed groups include -N(H)n-, -NH-(CO)-O-, -HN-(CO)-NH-, - -or One or more of the following; the degradation reaction includes alcoholysis; the degradation reaction may include the following reactions:

[0084] Alcohololysis: PU + HO-R-OH yields a mixture of polyols.

[0085] Furthermore, in step A, the initial polyurethane, serving as the initial polymer, is a polymeric compound containing chain-broken groups (AB), main chains X and Y, and is composed of initial isocyanate XA. a and the initial polyol YB b The reaction produces MC as the degradation agent. c The active group C of the degradation agent reacts with the chain-breaking group (AB) to break down the initial polyurethane molecules, forming a resin intermediate containing initial polymer molecule fragments with new active groups B and C. The degradation reaction is shown in the diagram below:

[0086]

[0087] Wherein, A represents the isocyanate group in the initial polyurethane, B represents the hydroxyl group in the initial polyurethane, and (AB) represents the urethane group in the initial polyurethane; X represents the initial isocyanate backbone; Y represents the initial polyol backbone; M represents the degradation agent backbone; C represents the active group of the degradation agent, including hydroxyl, active hydrogen, amine, or alkali metal groups; a, b, and c represent the functionality. The above is a typical degradation reaction mechanism, where a = 2, b = 3, and c = 2. Degradation reactions with other combinations of a, b, and c functional groups are similar and all fall within the scope of protection of this invention.

[0088] Furthermore, in step A, the degrading agent contains at least one active end group, which includes one or more of hydroxyl, carboxyl, anhydride, and carboxyl groups.

[0089] Preferably, the initial polyurethane includes urethane groups, and the degradation agent contains hydroxyl groups. In the degradation reaction, the hydroxyl groups react with the urethane groups and open at least a portion of the urethane bonds to generate a resin intermediate containing initial polyurethane molecular fragments with active amino and hydroxyl groups.

[0090] As a typical example of the present invention, the initial polymer is polyurethane, whose molecular backbone contains urethane groups, and the degradation reaction includes an alcoholysis reaction; the degrading agent contains active end groups of hydroxyl groups, which react with chain-breaking groups in the degradation reaction, and open at least a portion of the urethane bonds on the initial polymer molecular chain, generating a resin intermediate containing linear or branched molecular chain fragments of the initial polyurethane molecular fragments and the active hydroxyl groups. The degradation reaction includes the following reactions:

[0091] -R1NHCOOR2-+R3(OH)n→-R1NHCOOR3(OH) (n-1) -+-R2OH

[0092] Wherein, -NHCOO- is a urethane group; R3(OH)n is a degrading agent, n is greater than 1; -R1NHCOOR3(OH)(n-1)- is a molecular chain segment containing R1 and urethane groups and active hydroxyl groups from the initial polyurethane molecular chain; and -R2OH is a molecular chain segment containing R2 and at least one active hydroxyl group from the initial polyurethane molecular chain.

[0093] Furthermore, since the chemical structure of polyurethane contains not only urethane linkages -NHCOOR- but also urea linkages -NHCONHR-, the following side reactions also occur during the degradation reaction:

[0094] Side reactions of the urea group:

[0095] -R1-NH-CO-NH-R1-+HO-R3-OH→-R1NHCOOR3OH+-R1NH2

[0096] There are also side reactions such as the thermal degradation of carbamate and urea groups:

[0097] -R1-NH-CO-O-R2-→-RNCO+HOR2

[0098] -R1-NH-CO-O-(CH2)2-R2-→-R1NH2+CO2+CH2=CHR2

[0099] -R1-NH-CO-OO-R2-→-R1NHR2-+CO2

[0100] —R1-NH-CO-NH-R4-→-R1-NCO+R4NH2

[0101] The above-mentioned side reactions will eventually produce compounds with hydroxyl or amino groups.

[0102] The aforementioned side reactions will eventually generate compounds with hydroxyl or amino groups, which can react the grafting agent with compounds containing amino groups, or other active groups in the degradation agent, such as acid anhydrides or carboxyl groups, with compounds containing amino groups. This eliminates the need to separate and purify the amino compounds and polyols in the resin intermediates.

[0103] Furthermore, the degrading agent includes polyols, which include diols and / or highly functional polyols. Diols include low molecular weight C2-C6 diols, preferably ethylene glycol, propylene glycol, 1,4-butanediol, ethylene glycol monohydrate, propylene glycol monohydrate, or neopentyl glycol, etc. Highly functional polyols include glycerol, trimethylolethane, pentaerythritol, sucrose polyols, or sorbitol, and also include various polyether polyols based on small molecule initiators, such as NJ-301, NJ-303, NJ-3063, NJ-430H, NJ-6305C, NJ-403, NJ-4110, NJ-330N, NJ-204, etc.

[0104] Preferably, the initial polymer is polyurethane waste, including rigid foam for refrigerator insulation, rigid foam for cold storage insulation, rigid foam for refrigerated trucks and refrigerated containers insulation, rigid foam for building insulation and other rigid foams, soft foam for sofas, seats, and mattresses, packaging cushioning sponges, shoe soles, roller coatings, screens, conveyor belts, other elastomers, spandex, or TPU products. The method of manufacturing modified polyurethane through a degradation reaction yields resin intermediates, which can be used to manufacture polyurethane products, coatings, adhesives, and other chemicals, including rigid PU foam, flexible foam, elastomers, composite materials, epoxy resin crosslinking agents, unsaturated resins, vinyl resin modifiers, and crosslinking agents for polyurethane rubber.

[0105] Preferably, the weight ratio of polyurethane waste (PU) as the initial polymer to the degradation agent is 1:0.1-0.3, 1:0.3-0.5, 1:0.5-1, 1:1-2, 1:2-4, 1:4-8, or 1:8-15. If the proportion of PU is too high, only a partial reaction will occur, and the density and viscosity of the product will also increase accordingly. If the proportion is too low, the cost of deducting the amount of unreacted degradation agent will be too high.

[0106] Preferably, the alcoholysis reaction temperature is 110–150°C, 150–170°C, 170–180°C, 180–200°C, 200–220°C, or 220–250°C. Too low a reaction temperature prolongs the reaction time, while too high a reaction temperature, although beneficial for increasing the alcoholysis reaction rate and shortening the reaction time, increases the content of free amines in the final product, resulting in an excessively high amine value or hydroxyl value in the final product.

[0107] The alcoholysis reaction time is 0.5 h to 64 h, preferably 0.5 h to 2 h, 2 h to 3 h, 3 h to 6 h, 6 h to 12 h, 12 h to 24 h, 24 h to 48 h, or 48 h to 64 h.

[0108] Preferably, the yield of the alcoholysis reaction is 50–60%, 60–70%, 70–80%, 80–95%, or 95–100%.

[0109] Furthermore, the hydroxyl value of the resin intermediate obtained in step A is 10-50 mg KOH / g, 50-100 mg KOH / g, 100-180 mg KOH / g, 180-300 mg KOH / g, 300-500 mg KOH / g, 500-700 mg KOH / g, or 700-1000 mg KOH / g.

[0110] Furthermore, the viscosity (25°C) of the resin intermediate obtained in step A is 50–200 mPa·s, 200–500 mPa·s, 500–1000 mPa·s, 1000–2000 mPa·s, 2000–10000 mPa·s, 10000–20000 mPa·s, 20000–60000 mPa·s, 60000–200000 mPa·s, 200000–600000 mPa·s, and 600000–1800000 mPa·s.

[0111] Furthermore, the total amine value (KOH dosage) of the resin intermediate obtained in step A is 0–40 mg / g, 40–80 mg / g, 80–200 mg / g, or 200–1000 mg / g.

[0112] Furthermore, step A also includes a step of removing at least a portion of the degradation products, wherein the removal step includes one or more combinations of vacuum distillation, separation, filtration, extraction, and fractionation. Preferably, a vacuum distillation step is included to remove at least a portion of the unreacted degradation agent, which can be collected, recovered, and reused after removal. More preferably, the vacuum temperature is 65–95°C, 95–120°C, 120–150°C, or 150–200°C; and the vacuum distillation pressure is 0.01–2 mmHg, 2–5 mmHg, 5–20 mmHg, 20–100 mmHg, or 100–400 mmHg. Preferably, in step A, a diol is used as a degrading agent. Other highly functional polyols are added to the degradation product to reduce the viscosity of the reaction product. Then, all or part of the diol is removed by vacuum distillation for recycling. The weight ratio of diol to highly functional polyol is 1:0–0.3, 1:0.3–0.6, 1:0.6–1, 1:1–2, 1:2–4, or 1:4–9. If the proportion of diol is too high, there will be more residual diol in the product, making post-processing difficult. Simultaneously, the alcoholysis product containing free diol is difficult to completely remove, resulting in problems such as excessively high hydroxyl values ​​or difficulty in adjustment. Preferably, the diol is ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, diethylene glycol, or dipropylene glycol. The resulting resin intermediate has good properties and low viscosity.

[0113] On the other hand, the present invention claims protection for modified polymers prepared by any of the above methods as resin intermediates.

[0114] This invention also provides a method for grafting a modified polymer with a resin intermediate prepared by any of the above methods or a resin intermediate obtained by other means. The modified polymer is obtained by treating an initial polymer, and the treatment includes the following steps:

[0115] C: In step A, the degrading agent simultaneously carries active groups and chain-extending groups, thereby carrying out a grafting reaction while performing the degradation reaction, to obtain a modified polymer containing molecular fragments of the initial polymer and chain-extending groups as a modified resin.

[0116] Furthermore, the chain-extending group is a functional group capable of reacting with or interacting with other groups. Further, step C includes the following reaction:

[0117] R1-A-(R2S)+(R3C)-B-→R1-(A1C)-R3-B1-+(CR2S)-B2-

[0118] Wherein, -R1-A-(R2S)- is the initial polymer, A is the chain-breaking group, S is the side group, (R3C)-B- is the degrading agent with both active and chain-extending groups, -C- is the chain-extending group; -B- is the active group of the degrading agent; R1-(A1)-R3-B1- and (R2S)-B2- are the initial polymer molecular fragments formed after the initial polymer chain is broken, -A1- is the group formed after the chain-breaking group A is degraded, and -B1- and -B2- are the active groups formed at both ends of the molecular chain by the active end group B of the degrading agent. The initial polymer molecular fragments R1-(A1C)-R3-B1- and (CR2S)-B2- with chain-extending groups C can achieve molecular chain growth and / or cross-linking through the reaction of chain-extending groups C with other groups or the mutual reaction of chain-extending groups C to obtain modified polymers.

[0119] On the other hand, the present invention can also provide a method for grafting a modified polymer with the resin intermediate prepared by any of the above methods to obtain the modified polymer, wherein the modified polymer is obtained by treating the initial polymer, and the treatment includes the following steps:

[0120] C: After step A, the obtained resin intermediate is subjected to a grafting reaction with a grafting agent that simultaneously carries grafting groups and chain extender groups to obtain a modified polymer containing molecular fragments of the initial polymer and chain extender groups as a modified resin.

[0121] Furthermore, the grafting group is a functional group that can react with the active end groups in the resin intermediate, and the chain extension group is a functional group that can react with other groups or react with each other.

[0122] Furthermore, the manufacture of the modified polymer includes the following reactions:

[0123] R1-A-(R2S)+(R3)-B-→R1-(A1)-R3-B1-+(R2S)-B2-+(R4D)-C-→R1-(A1)-R3-(B1DR4)-C-+(R2S)-(B2DR4)-C-

[0124] Wherein, -R1-A-(R2S)- is the initial polymer, A is the chain-breaking group, S is the side group, R3-B- is the degrading agent, and -B- is the active group of the degrading agent; R1-(A1)-R3-B1- and (R2S)-B2- are the initial polymer molecular fragments formed after the initial polymer chain is broken, -A1- is the group formed after the chain-breaking group A is degraded, and -B1- and -B2- are the active groups formed at both ends of the molecular chain by the active end group B of the degrading agent. The active groups A1, B1, or B2 participate in the subsequent reactions.

[0125] (R4D)-C- is a grafting agent, and D is a grafting group. It is used to react with the active groups A1, B1, and B2 in the resin intermediate to attach grafting agent molecules with chain extender C to the initial polymer molecular fragments in the resin intermediate. This allows these initial polymer molecular fragments to be reconnected through chain growth and / or crosslinking reactions of the chain extender C to obtain a modified polymer. C is a chain extender group, and D can be a side group or on the main chain. It can be connected to a direct grafting group or a chain extender group, or it can be not connected to a grafting group or a chain extender group.

[0126] According to any of the above methods for obtaining modified polymer resins through grafting reaction treatment, the present invention further provides the following preferred embodiments.

[0127] Furthermore, in step A, the initial polymer is polyurethane, including thermoplastic polyurethane (TPU) with a linear or branched molecular structure and thermosetting polyurethane with a cross-linked network molecular structure. The polyurethane's main molecular chain contains urethane groups, and the degradation agent contains hydroxyl groups. In the degradation reaction, the hydroxyl groups react with the urethane groups, opening at least a portion of the urethane bonds on the initial polymer molecular chain to generate molecular chain fragments with linear or branched molecular structures containing aminomethyl ester groups and / or hydroxyl groups.

[0128] Furthermore, the initial polymer molecular chain contains chain-severed groups, including -N(H)n-, -NH-(CO)-O-, -HN-(CO)-NH-, - One or more of the following; the degradation reaction includes alcoholysis; the degradation agent includes one or more of the following: polyols, acids, acid anhydrides, and carboxylates.

[0129] Furthermore, in step C, the grafting group includes one or more combinations of hydroxyl, carboxyl, and acid anhydride, and the chain extension group includes one or more combinations of hydroxyl, carboxyl, and carboxylate.

[0130] Furthermore, in step A, the initial polyurethane is Y(BA). (b-a) X(AB) a Y, from the initial isocyanate XA a and the initial polyol YB b The reaction produces MC as the degradation agent. c The degradation reaction includes the following reactions:

[0131]

[0132] Furthermore, in step C, the grafting agent is D. d NE e The grafting reaction includes the following reactions:

[0133]

[0134] Wherein, A is the isocyanate group in the initial polyurethane, B is the hydroxyl group in the initial polyurethane, (AB) is the urethane group in the initial polyurethane; X is the initial isocyanate backbone; Y is the initial polyol backbone; M is the degradation agent backbone; C is the active group of the degradation agent, including hydroxyl, active hydrogen, amine, and alkali metal groups; the chain-breaking group of the initial polyurethane is (AB); N is the grafting agent backbone, which can participate in the molecular morphology modification of the cured polyurethane resin; D is the grafting group, which can react with (AC) and B to generate (ACD) and (BD), so that the initial polymer molecular fragments in the resin intermediate are attached with grafting agent molecules containing chain extender E; E is the chain extender group, which allows the initial polymer molecular fragments to be reconnected through chain growth and / or cross-linking reactions of the chain extender group E to obtain the modified polymer; a, b, c, d, and e are the functions, respectively. The above is a typical degradation reaction mechanism, in which a=2, b=3, c=1, d=1, e=1. The degradation reactions of other functional combinations of a, b, c, d, e are similar and all fall within the protection scope of this invention.

[0135] Furthermore, in step A, the initial polymer contains —R1NHCOOR2— units; the degrading agent includes a compound R3(OH)n with a hydroxyl group; the degradation reaction comprises the following reaction:

[0136] -R1NHCOOR2-+R3(OH)n→-R1NHCOOR3(OH) (n-1) -+-R2OH

[0137] Furthermore, in step C, the grafting agent contains chain-extending groups including unsaturated double bonds, and the grafting groups include carboxyl or anhydride groups; the grafting reaction includes the following reaction:

[0138] -R1NHCOOR3(OH) (n-1) -+-R2OH+R4-(C=C) a -(CR5) b -(COOH)m→-R1NHCOOR3O-(CO)-(CR5) b -(C=C) a -R4+R2-O-(CO)-(CR5) b -(C=C) a -R4+H2O

[0139] or

[0140] -R1NHCOOR3(OH) (n-1) -+-R2OH+-R4-(C=C) a -(CR5) b -(CO)O(CO)-→-R1NHCOOR3O-(CO)-(CR5) b -(C=C) a -R4-+-R2-O-(CO)-(CR5) b -(C=C) a -R4-

[0141] Wherein, -R2OH+R4-(C=C)a-(CR5)b-(COOH)m and R4-(C=C)a-(CR5)b-(CO)O(CO)- are grafting agents, which bear grafting groups, including carboxyl groups -(COOH)m or acid anhydride groups -(CO)O(CO)-. Preferably, a = 1 to 6, which is the functionality of the unsaturated double bond functional group -(C=C)a- of the grafting agent. More preferably, b = 0 to 6, which is the number of carbon atoms of the unsaturated double bond from the grafting group. -R4- and R5 are side groups of the grafting agent main chain, including H atoms, methyl groups, and other organic groups. The grafting agent includes acids, acid anhydrides, or carboxylates with unsaturated double bonds.

[0142] Furthermore, in step A, the initial polymer contains -R1NHCOOR2- units; the degrading agent includes an acid, anhydride, or anhydride salt with unsaturated double bonds; the degradation reaction comprises the following reactions:

[0143] -R1NHCOOR2-+R4-(C=C) a -(CR5) b -(COOH)m→R1-NH-(CO)-(CR5) b-(C=C) a -R4+R2-O-(CO)-(CR5) b -(C=C) a -R4+CO2

[0144] or

[0145] -R1NHCOOR2-+-R4-(C=C) a -(CR5) b -(CO)O(CO)-→-R1NH-(CO)-(CR5) b -(C=C) a -R4-+-R2-O-(CO)-(CR5) b -(C=C) a -R4-+CO2

[0146] In this context, R4-(C=C)a-(CR5)b-(COOH)m and R4-(C=C)a-(CR5)b-(CO)O(CO)- are grafting agents, each containing a grafting group. This grafting group includes a carboxyl group (-(COOH)m) or an anhydride group (-(CO)O(CO)-). a = 1–6 represents the functionality of the unsaturated double bond functional group (-(C=C)a-) in the grafting agent, and b = 0–6 represents the number of carbon atoms from the unsaturated double bond to the grafting group. -R4- and R5 are side groups of the grafting agent's main chain, including H atoms, methyl groups, and other organic groups. Grafting agents include maleic anhydride and esters, acids, anhydrides, or carboxylates containing unsaturated double bonds.

[0147] Furthermore, in step C, when the initial polymer contains -R1NHCOOR2- units; the grafting agent includes an acid, anhydride, or anhydride salt with unsaturated double bonds; the grafting reaction also includes an amide condensation reaction, comprising the following reaction:

[0148] -R-NH-R'+R4-(C=C) a -(CR5) b -(COOH)m→R-NR'-(CO)-(CR5) b -(C=C) a -R4

[0149] or

[0150] -R-NH-R'+-R4-(C=C) a -(CR5) b -(CO)O(CO)-→R-NR'-(CO)-(CR5) b -(C=C) a -R4

[0151] Among them, R4-(C=C)a-(CR5)b-(COOH)m and R4-(C=C)a-(CR5)b-(CO)O(CO)- are grafting agents, which contain grafting groups, including carboxyl groups -(COOH)m or acid anhydride groups -(CO)O(CO)-. a = 1–6, representing the functionality of the unsaturated double bond functional group -(C=C)a- of the grafting agent; b = 0–6, representing the number of carbon atoms from the unsaturated double bond to the grafting group; —RN-R' is an amine-containing compound, with R as the main chain and R' as a side group attached to the N atom, including H atoms, methyl groups, and other organic groups. Grafting agents include acrylates, maleic anhydrides, esters with unsaturated double bonds, acids, acid anhydrides, or carboxylates. Amide condensation reactions allow the grafting groups to react simultaneously with hydroxyl and amine groups, thus eliminating the need to separate and purify the amino compound and polyol in the resin intermediate.

[0152] On the other hand, the present invention claims protection for modified polymers prepared by any of the above-described grafting reaction methods.

[0153] Furthermore, in step A, the initial polymer is polyurethane, including thermoplastic polyurethane (TPU) with a linear or branched molecular structure and thermosetting polyurethane with a cross-linked network molecular structure. The initial polymer molecular chain contains chain-severed groups, including -N(H)n-, -NH-(CO)-O-, -HN-(CO)-NH-, - One or more of the following; the degradation reaction includes alcoholysis; further, the degrading agent includes one or more of the following: polyols, acids, acid anhydrides, and carboxylates;

[0154] Preferably, in step C, the grafting group includes one or more combinations of hydroxyl, carboxyl, acid anhydride, and carboxylate, and the chain extension group includes one or more combinations of hydroxyl, carboxyl, and unsaturated double bond.

[0155] Preferably, in step C, the chain-extending group comprises an unsaturated double bond.

[0156] Further, in step A, the initial polymer is polyurethane, including thermoplastic polyurethane (TPU) with a linear or branched molecular structure and thermosetting polyurethane with a cross-linked network molecular structure. The main molecular chain contains urethane groups, and the degradation agent contains hydroxyl groups. In the degradation reaction, the hydroxyl groups react with the urethane groups and open at least a portion of the urethane bonds on the initial polymer molecular chain, generating molecular chain fragments with linear or branched molecular structures containing aminomethyl ester groups and / or hydroxyl groups. The initial polymer molecular chain contains chain-severing groups, including -N(H)n-, -NH-(CO)-O-, -HN-(CO)-NH-, - One or more of the following; the degradation reaction includes alcoholysis; the degradation agent includes one or more of the following: polyols, acids, acid anhydrides, and carboxylates;

[0157] Preferably, in step C, the grafting group includes one or more combinations of hydroxyl, carboxyl, acid anhydride, and carboxylate, and the chain extension group includes one or more combinations of hydroxyl, carboxyl, and unsaturated double bond.

[0158] Preferably, in step A, the initial polymer is polyurethane, the main chain of which contains urethane groups, and the degradation agent contains hydroxyl groups. In the degradation reaction, the hydroxyl groups react with the urethane groups and open at least a portion of the urethane bonds on the initial polymer molecular chain to generate molecular chain fragments containing urethane groups and / or hydroxyl groups in a linear or branched molecular structure.

[0159] On the other hand, the present invention claims protection for modified polymers prepared by any of the above-mentioned methods of curing reaction treatment.

[0160] According to any of the above methods for preparing modified polymers, the present invention also provides the following preferred embodiments.

[0161] In a preferred embodiment, the following steps are included after step A:

[0162] B: Remove and recover excess degradation agent from the resin intermediate obtained in step A. Further, the removal methods include one or more combinations of vacuum distillation, thin-film evaporation, extraction purification, fractionation, rectification, and precipitation.

[0163] In a preferred embodiment, the following steps are included after step C:

[0164] Step D: The modified resin obtained in step C is filtered, impurities are removed, and the resin is dried. Further, the filtration methods include pressure filtration and vacuum filtration.

[0165] In a preferred embodiment, step A includes an alcoholysis reaction.

[0166] In a preferred embodiment, the degradation agent is an alcoholysis agent, which includes monomers, oligomers or polymers having 1 to 6 hydroxyl groups.

[0167] In a preferred embodiment, the degrading agent is a polyol with a functionality of 2-6 and a main chain containing 2-10 methylene groups.

[0168] In a preferred embodiment, the degrading agent is a polyol with a functionality of 2-4, containing 2-6 methylene groups in the main chain and ether bonds, which can improve the toughness of polyurethane while maintaining its strength.

[0169] In a preferred embodiment, the degrading agent includes one or more selected from 1,2-propanediol, ethylene glycol, butanediol, pentanediol, hexanediol, diethylene glycol, 1,6-hexanediol, polyether polyols with a molecular weight less than 700, or polyether polyols with a molecular weight greater than 800. Preferably, it is selected from ethylene glycol, diethylene glycol, dipropylene glycol, or glycerol, with a molecular weight of 200-700 and a functionality of 2-4, which can yield a homogeneous resin intermediate that can be used directly without separation or purification.

[0170] In a preferred embodiment, the active end groups in the resin intermediate include one or more of hydroxyl, carboxyl, and unsaturated double bonds.

[0171] In a preferred embodiment, the grafting agent contains unsaturated double bonds and one or more compounds including, but not limited to, hydroxyl, carboxyl, and acid anhydride groups.

[0172] In a preferred embodiment, the initial polymer comprises one or more cured polyurethanes, the cured polyurethanes including polyurethane waste.

[0173] Preferably, the initial polymer accounts for no less than 20% of the resin intermediate, more preferably no less than 40%. More preferably, no less than 60%, more preferably, no less than 70%, and even more preferably, no less than 80%, which can reduce costs and improve the properties of the modified resin, such as elongation at break.

[0174] In a preferred embodiment, the number-average molecular weight of the resin intermediate, measured using both RID and VWD (254nm) detectors, is in the range of 150–200; 200–350; 350–700; 700–1000; 700–1000; 1000–1800; 1800–3000; 3000–5000; 5000–10000; 10000–30000; 30000–60000 g / mol.

[0175] In a preferred embodiment, the hydroxyl value of the modified resin is in the range of 0–50, 50–100, 100–200, 200–500, or 500–800 mg KOH / g.

[0176] As a preferred embodiment, the acid value of the modified resin is 0-8, 8-16, 16-30, 30-100, or 100-200 mgKOH / g.

[0177] As a preferred embodiment, the amine value of the modified resin is 0-20, 20-40, 40-80, or 80-150 mgKOH / g.

[0178] In a preferred embodiment, the amine value of the resin intermediate is 0–20, 20–30, 30–40, 40–50, 50–60, 60–80, 80–100, 100–120, 120–150, 150–180, 180–230, 230–280, or 280–500 mg KOH / g.

[0179] In a preferred embodiment, the presence of an absorption peak at 1680 cm⁻¹ to 1780 cm⁻¹ in the infrared spectrum of the resin intermediate or modified resin using an infrared spectrometer confirms that the resin intermediate or modified resin contains urethane functional groups.

[0180] In a preferred embodiment, the grafting agent in the grafting reaction includes one or more selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

[0181] In a preferred embodiment, the total mass of the degrading agent in the degradation reaction is 0.5-10 times the initial polymer. This range of degrading agents is sufficient to achieve the reaction without requiring excessive subsequent vacuum distillation.

[0182] In a preferred embodiment, the total mass of the unsaturated carboxylic acid or unsaturated carboxylic anhydride used as the grafting agent is 0.2-10 times that of the polymer resin intermediate. This allows for a higher reaction yield.

[0183] In a preferred embodiment, when the grafting agent reacts with the resin intermediate, the ratio of the total molar number of carboxylic acids or unsaturated carboxylic anhydrides used as the grafting agent to the molar number of hydroxyl groups in the resin intermediate is 0.8-1.2. In this case, the unsaturated carboxylic acids and the hydroxyl groups in the resin intermediate react almost completely, eliminating the need for vacuum distillation to remove excess acid, anhydride, or carboxylate, thus reducing the number of process steps.

[0184] In a preferred embodiment, the initial polymer comprises one or more cured polyurethanes. The cured polyurethane includes polyurethane waste, or a modified resin is obtained by blending different resins made from different initial polymers. Preferably, the initial polymer constitutes at least 20% of the modified resin, more preferably at least 40%. More preferably, at least 60%, and even more preferably, at least 70%, which can reduce costs and improve the properties of the modified resin, such as elongation at break.

[0185] In a preferred embodiment, the initial polymer comprises one or more cured polyurethanes, the cured polyurethanes including polyurethane waste.

[0186] In a preferred embodiment, the initial polymer resin is widely available. It can be obtained not only through direct curing of raw materials and polyurethane, but also from polyurethane waste, such as rigid insulation foam commonly used in refrigerators and containers, flexible polyurethane foam used in mattresses and sofas, polyurethane elastomer screens used in mining, and polyurethane elastomer rollers. The use of polyurethane waste not only reduces the cost of new polyurethane but also increases the utilization value of polyurethane waste, contributing to improved polyurethane recycling levels. This invention, applied to the recycling of polyurethane, can solve key technical problems in existing polyurethane recycling technologies. Existing polyurethane recycling technologies require the initial polymer to be converted into standard chemical raw materials to produce polyurethane that meets performance requirements. This necessitates complex decomposition and purification steps, which are technically complex, energy-intensive, and produce byproduct pollution. This technology eliminates these steps.

[0187] Furthermore, the weight ratio of acid anhydride to alcoholysis agent is 1 / 100, preferably 1 / 75, preferably 1 / 50, preferably 1 / 35, preferably 1 / 20, preferably 1 / 18, preferably 1 / 15, preferably 1 / 12, preferably 1 / 10, preferably 1 / 8, preferably 1 / 6, preferably 1 / 4, preferably 1 / 3.

[0188] This invention provides a method for treating initial polymers, employing a simple and efficient polyurethane degradation method, particularly optimizing the alcoholysis process, to further obtain low-amine-value polyol products. In the polyurethane alcoholysis process, this invention involves adding a certain amount of acid anhydride or a corresponding acid to an alcohol reagent before reacting it with polyurethane waste, which efficiently yields low-amine-value alcoholysis polyol products. The acid anhydride can be a monocarboxylic acid anhydride, such as acetic anhydride, hexanoic anhydride, benzoic anhydride, etc.; it can also be a cyclic anhydride, with many options available, including monofunctional anhydrides, difunctional anhydrides, free acid anhydrides, or mixtures thereof, such as succinic anhydride, methylhexahydrophthalic anhydride, chlorogenic anhydride, pyromellitic anhydride, trimellitic anhydride, etc.

[0189] Furthermore, the modified polyol product obtained from this alcoholysis reaction can be reused to prepare new polyurethane products in a mass ratio ranging from 5 / 95 to 55 / 45 with ordinary polyols (i.e., polyols obtained by conventional industrial ring-opening of ethylene oxide, propane, or butane, or polyester polyols, etc.). The properties of these new polyurethane products are similar to those of the original PU products (i.e., ordinary polyols obtained without adding any recycled products). This achieves a closed loop from polyurethane product production to recycling and reprocessing into new products, improving the industry's production efficiency and economic value, and has broad market application prospects.

[0190] Furthermore, the present invention has surprisingly discovered that if the degradation reaction does not involve water, hydrogen peroxide, and free radical initiators, but only acid anhydrides or acids are added during the alcoholysis process, the amine value of the polyol product can be further reduced, and the particle size of the polyol product will also be smaller, making it more suitable as a polyol raw material for use in the preparation of new polyurethane materials. Attached Figure Description

[0191] The above description of the present invention and the following detailed embodiments will be better understood when read in conjunction with the accompanying drawings. It should be noted that the drawings are merely examples of the claimed technical solutions.

[0192] Figure 1 This is the JJ / CJ-3 / SJZH-2 infrared spectrum of embodiment G1 of the present invention;

[0193] Figure 2 This is the CJ35 / H12 infrared spectrum of embodiment G2 of the present invention;

[0194] Figure 3 This is the MB1C infrared spectrum of embodiment G6 of the present invention;

[0195] Figure 4 This is the MB1 infrared spectrum of embodiment G7 of the present invention. Detailed Implementation

[0196] The detailed features and advantages of this patent are described below in the specific embodiments. The content is sufficient to enable any person skilled in the art to understand the technical content of this patent and implement it accordingly. Furthermore, based on the specification and claims disclosed in this specification, a person skilled in the art can easily understand the related objectives and advantages of this patent.

[0197] To make the purpose, technical solution and advantages of this patent clearer, the implementation method of this patent will be described in further detail below.

[0198] The raw materials used in this embodiment are commercially available. Diphenylmethane diisocyanate (PMDI): trade name 44V20L, purchased from Covestro; polyols NJ-303 and NJ-204, purchased from Jurong Ningwu New Materials Co., Ltd.

[0199] Test Example 1

[0200] The hydroxyl value testing methods used in this invention are all ASTM E1899-2016.

[0201] Test Example 2

[0202] All methods used in this invention for testing amine values ​​are: amine values ​​measured by potentiometric titration.

[0203] The amine value is the number of milligrams of potassium hydroxide required to neutralize one gram of basic amine. The amine value is commonly used to indicate the functionality of polyols. This experiment uses the perchloric acid-glacial acetic acid titration method, with automatic titration performed using a potentiometric titrator, and the amine value of the sample calculated after analysis.

[0204] 1. Prepare reagents and instruments

[0205] Sample: Hydroxyl-containing compound (i.e., modified polyol product)

[0206] Titrant: 0.1 mol / L perchloric acid-glacial acetic acid standard solution

[0207] Solvents: glacial acetic acid and acetonitrile

[0208] Instruments: Lei magnetic potential titrator (model ZDJ-4B), titration stirring table, non-aqueous electrode (filled with ethanol-saturated lithium chloride), 4.100mL titration cup, electronic balance (accurate to 0.1mg), beaker, graduated cylinder, volumetric flask, etc.

[0209] 2. Measurement Method

[0210] Weigh approximately 0.2 g of the sample and dissolve it in 20 mL of glacial acetic acid. Then add 20 mL of acetonitrile to dilute the solution. After stirring until the sample dissolves, transfer the solution to a titration cup and place it on the titration stage. Set the instrument titration method according to the following parameters and perform titration analysis using a 0.1 mol / L standard perchloric acid-acetic acid solution. Obtain the results after the analysis is completed.

[0211] The parameters of the titrator are as follows:

[0212] Endpoint mode: Differential determination;

[0213] Endpoint volume determination: 5 units before; 0.3 units after.

[0214] Minimum dropping volume: 10 μL;

[0215] Maximum dropping volume: 1000uL;

[0216] Endpoint determination differential value: 200;

[0217] Pre-titration: None;

[0218] Stirring speed: 200;

[0219] Interval between drops: 2000 m / s;

[0220] The formula for calculating the amine value is: Amine value = C * V * 56.11 / m

[0221] Where: V—titer endpoint volume (ml); C—concentration of perchloric acid-glacial acetic acid standard solution (mol / L); m—sample amount (g); 56.11—molar mass of potassium hydroxide (g / mol).

[0222] Test Example 3

[0223] The method used in this invention for testing hydroxyl values ​​is ASTM E1899-2016.

[0224] Example G1

[0225] Under nitrogen protection, 80 g of maleic anhydride and 800 g of ethylene glycol were mixed, heated to 50 °C and stirred for 1 hour to dissolve evenly, thus obtaining a degradation agent. Then, 200 g of polyurethane waste (recycled refrigerator rigid foam waste) was added to the degradation agent, and the mixture was heated and stirred for 12 hours until the polyurethane solid dissolved, with the heating temperature maintained at 184 °C, to obtain a reaction mixture. The reaction mixture was then cooled to 120 °C, filtered through a filter (60 μm pore size), and cooled to room temperature to obtain a filtrate and a filter cake containing the modified polyol product. The obtained filter cake was dissolved in 10 times its volume of methanol and then filtered through slow-speed filter paper with a 13 μm pore size. The remaining solid on the filter paper was dried and weighed to be 20 g. The obtained filtrate was subjected to vacuum distillation to remove excess ethylene glycol, yielding 330g of a modified polyol product numbered JJ / CJ-3 / SJZH-2. The viscosity was greater than 30000 mPa·s, and it was a brown paste at room temperature. The initial polyurethane content in the modified polyol product was (200-20) / 330 = 54.5 wt%. The obtained product contained amide groups. The amine value of the modified polyol product was tested to be 16 mg KOH / g, and the hydroxyl value was 360 mg KOH / g. This modified polyol product can be used to manufacture rigid polyurethane foam.

[0226] The modified polyol product obtained in this embodiment was mixed with PMDI at a weight ratio of 1:1 to prepare a cured polyurethane with uniform quality.

[0227] The infrared spectrum of the JJ / CJ-3 / SJZH-2 modified polyol product was measured according to the general rules of infrared spectroscopy analysis GB / T 6040, as follows: Figure 1 As shown in Table G1, the peak data of the infrared spectrum can be observed at 1680 cm⁻¹. -1 ~1780cm -1 1713.25cm in the wavenumber range -1 A distinct absorption peak appears at 1090–1210 cm⁻¹. -1 1172.18 cm in the wavenumber range -1 It has a distinct single absorption peak at 1610 cm⁻¹. -1 and 1480cm -1 ~1570cm -11510cm in the wavenumber range -1 A distinct absorption peak also appeared nearby.

[0228] Table G1: Infrared spectral peak data of modified polyol product JJ / CJ-3 / SJZH-2

[0229] Peak position 1172.18 strength 0.233 Peak position 1513.07 strength 0.18 Peak position 1611.33 strength 0.086 Peak position 1713.25 strength 0.301

[0230] As can be seen from Table G1, the height ratio of peak 1713.25 to peak 1513.07 is 1.67 / 1.

[0231] Example G2

[0232] Under nitrogen protection, 80 g of succinic anhydride and 600 g of propylene glycol were mixed, then heated to 95°C and stirred for 1 hour to dissolve evenly, yielding a degradation agent. Then, 200 g of polyurethane waste (recycled container rigid foam waste) was added to the degradation agent, and the mixture was heated and stirred for 10 hours until the polyurethane solid dissolved, while maintaining the temperature at 180°C, to obtain a reaction mixture. The reaction mixture was then cooled to 120°C, filtered through a 75 μm filter, and cooled to room temperature to obtain a filtrate and filter cake containing modified polyol products. The filter cake was dissolved in 10 times its volume of methanol and then filtered through slow-speed filter paper with a pore size of 13 μm. The remaining solid on the filter paper was dried and weighed to be 18 g. The hydroxyl value of the filter cake was 14 mg KOH / g, and the hydroxyl value was 140 mg KOH / g. It can be used as an active filler for polyols. The filtrate was distilled under reduced pressure to remove excess propylene glycol, yielding 360 g of modified polyol product CJ35 / H12. The viscosity was greater than 30000 mPa·s, and it was a brown paste at room temperature. The initial polyurethane content in the modified polyol product was (200-18) / 360 = 50.5 wt%. The obtained product contained amide groups. The amine value of the modified polyol product was tested to be 23 mg KOH / g, and the hydroxyl value was 380 mg KOH / g, as determined according to DIN 53176. The modified polyol product obtained in this example was mixed with PMDI at a weight ratio of 1:1 to prepare a uniformly cured polyurethane.

[0233] This modified polyol product can be used to manufacture rigid polyurethane foam.

[0234] The infrared spectrum of the CJ35 / H12 modified polyol product was measured according to the general rules of infrared spectroscopy analysis GB / T 6040, as follows: Figure 2 As shown in Table G2, the peak data of the infrared spectrum can be observed at 1680 cm⁻¹. -1 ~1780cm -1 1719.34 cm in the wavenumber range -1 A distinct absorption peak appears at 1090–1210 cm⁻¹. -1 1184.74 cm in the wavenumber range-1 It has a distinct single absorption peak at 1610 cm⁻¹. -1 and 1480cm -1 ~1570cm -1 1510cm in the wavenumber range -1 A distinct absorption peak also appeared nearby.

[0235] Table G2: Infrared spectral peak data of modified polyol product CJ35 / H12

[0236] Peak position 1184.74 strength 0.195 Peak position 1510.43 strength 0.173 Peak position 1602.41 strength 0.122 Peak position 1719.34 strength 0.127

[0237] As can be seen from Table G2, the height ratio of peak 1719.34 to peak 1510.43 is 0.73 / 1.

[0238] Example G3

[0239] Under nitrogen protection, 80 g of phthalic anhydride and 300 g of diethylene glycol were mixed, then heated to 80 °C and stirred for 1 hour to dissolve evenly, yielding a degradation agent. Next, 600 g of polyurethane waste (recycled polyurethane flexible foam waste) was added to the degradation agent, and the mixture was heated and stirred for 16 hours until the polyurethane solid dissolved, maintaining the temperature within the range of 200 °C, to obtain a reaction mixture. The reaction mixture was then cooled to 140 °C, filtered through a 270 μm filter, and cooled to room temperature to obtain a filtrate and filter cake containing modified polyol products. The filter cake was dissolved in 10 times its volume of methanol and filtered through slow-speed filter paper with a pore size of 13 μm. The remaining solid on the filter paper was dried and weighed to be 226 g. The hydroxyl value of the filter cake was 16 mg KOH / g, and the hydroxyl value was... The concentration of KOH is 36 mg / g, which can be used as an active filler for polyols. The filtrate is distilled under reduced pressure to remove excess diethylene glycol, yielding 530 g of the modified polyol product. The viscosity is greater than 20000 mPa·s, and it is a brown paste at room temperature. The initial polyurethane content in the modified polyol product is (600-226) / 530 = 70.6 wt%. The obtained product contains amide groups. According to DIN53176, the amine value of this modified polyol product is 54 mg KOH / g, and the hydroxyl value is 156 mg KOH / g. The amine value of the modified polyol product in this embodiment is lower than that obtained by existing methods, indicating that the process optimization of this invention further reduces the amine value of the modified polyol product. Furthermore, the modified polyol product of this embodiment can be measured with infrared spectra according to the general rules of infrared spectroscopy analysis GB / T 6040. The modified polyol product has infrared absorption peaks in the wavenumber ranges of 1680cm-1 to 1780cm-1, 1480cm-1 to 1570cm-1, and 1100cm-1 to 1210cm-1, and the peak height of the infrared absorption peak in the wavenumber range of 1680cm-1 to 1780cm-1 is not less than 70% of the peak height of the infrared absorption peak in the wavenumber range of 1480cm-1 to 1570cm-1.

[0240] The modified polyol product obtained in this embodiment was mixed with PMDI at a weight ratio of 1:1 to prepare a cured polyurethane with uniform quality.

[0241] This modified polyol product can be used to manufacture polyurethane flexible foam. Specifically, the modified polyol product can be reacted with commercially available diisocyanate as raw material, and a catalyst, foaming agent, and foam stabilizer can be added. After mixing and stirring, the foam is foamed and cured. According to the GB / T10802-2023 General Flexible Polyurethane Foam Testing Standard, the tensile strength and tensile modulus of this polyurethane flexible foam will increase, as will the tensile strength, tear strength, and resilience of the flexible foam. Due to its low amine value, this polyurethane flexible foam has good safety.

[0242] Example G4

[0243] Under nitrogen protection, 80 g of methyltetrahydrophthalic anhydride, 200 g of ethylene glycol, and 200 g of NJ204 (hydroxyl value 280) were mixed, then heated to 70°C and stirred for 1 hour to dissolve evenly, yielding a degradation agent. Then, 300 g of polyurethane waste (recycled shoe sole material) was added to the degradation agent, and the mixture was heated and stirred for 6 hours until the polyurethane solid dissolved, maintaining the temperature within the range of 210°C, yielding a reaction mixture. The reaction mixture was then cooled to 120°C, filtered through a 20 μm filter, and cooled to room temperature, yielding a filtrate and a filter cake containing the modified polyol product. The filter cake was dissolved in 10 times its volume of methanol and filtered through slow-speed filter paper with a pore size of 13 μm. The remaining solid on the filter paper was dried and weighed to be 115 g. The hydroxyl value of the filter cake was 12 mg KOH, and the amine value was 12 mg KOH. / g, with a hydroxyl value of 85mgKOH / g, can be used as an active filler for polyols; the obtained filtrate is distilled under reduced pressure to remove excess ethylene glycol, yielding 525g of modified polyol product with a viscosity greater than 10000mPa.s, which is a brown paste at room temperature. The initial polyurethane content in the modified polyol product is (300-115) / 525 = 32.5wt%. The obtained product contains amide groups. According to DIN53176, the amine value of the modified polyol product is 45mgKOH / g, and the hydroxyl value is 171mgKOH / g. The amine value of the modified polyol product in this embodiment is lower than that of the modified polyol product obtained by the prior art method, indicating that the process optimization of the present invention further has the effect of reducing the amine value of the modified polyol product. Furthermore, the modified polyol product of this embodiment can be measured with infrared spectra according to the general rules of infrared spectroscopy analysis GB / T 6040. The modified polyol product has infrared absorption peaks in the wavenumber ranges of 1680cm-1 to 1780cm-1, 1480cm-1 to 1570cm-1, and 1100cm-1 to 1210cm-1, and the peak height of the infrared absorption peak in the wavenumber range of 1680cm-1 to 1780cm-1 is not less than 70% of the peak height of the infrared absorption peak in the wavenumber range of 1480cm-1 to 1570cm-1.

[0244] The modified polyol product obtained in this embodiment was mixed with PMDI at a weight ratio of 1:1 to prepare a cured polyurethane with uniform quality.

[0245] This modified polyol product can be used to manufacture elastomers such as polyurethane shoe soles. Specifically, the modified polyol product can be reacted with commercially available diisocyanate prepolymer as raw material, and after mixing and stirring, foaming and curing are carried out to obtain a polyurethane elastomer. According to the ASTM D412-16(2021) elastomer testing standard, the tensile strength and tensile modulus of this polyurethane elastomer will increase. Due to its low amine value, the polyurethane elastomer has good safety.

[0246] Example G5

[0247] Under nitrogen protection, 30 g of maleic anhydride, 20 g of succinic anhydride, 30 g of phthalic acid, 300 g of ethylene glycol, 300 g of propylene glycol, and 6 g of tetrabutyl titanate were mixed and heated to 95°C and stirred for 1 hour to dissolve evenly, yielding a degradation solution. Then, 200 g of polyurethane waste (recycled rigid building insulation foam waste) was added to the degradation solution, and the mixture was heated and stirred for 4 hours until the polyurethane solid dissolved, maintaining the temperature within the range of 190°C. The reaction mixture was then cooled to 120°C, filtered through a 20 μm filter, and cooled to room temperature to obtain a filtrate and a filter cake containing modified polyol products. The filter cake was dissolved in 10 times its volume of methanol and filtered through slow-speed filter paper with a pore size of 13 μm. The remaining solid on the filter paper was dried and weighed to be 85 g. The hydroxyl value of the filter cake was 17m (amine value). The modified polyol product has a KOH / g content and a hydroxyl value of 167 mgKOH / g, and can be used as an active filler for polyols. The filtrate is distilled under reduced pressure to remove excess propylene glycol, yielding 265 g of modified polyol product with a viscosity greater than 10000 mPa·s. It is a brown paste at room temperature. The initial polyurethane content in the modified polyol product is (200-85) / 265 = 43.4 wt%. The product contains amide groups. According to DIN53176, the amine value of the modified polyol product is 51 mgKOH / g, and the hydroxyl value is 420 mgKOH / g. The amine value of the modified polyol product in this embodiment is lower than that of the modified polyol product obtained by the prior art method, indicating that the process optimization of the present invention further reduces the amine value of the modified polyol product. Furthermore, the modified polyol product of this embodiment can be measured with infrared spectra according to the general rules of infrared spectroscopy analysis GB / T 6040. The modified polyol product has infrared absorption peaks in the wavenumber ranges of 1680cm-1 to 1780cm-1, 1480cm-1 to 1570cm-1, and 1100cm-1 to 1210cm-1, and the peak height of the infrared absorption peak in the wavenumber range of 1680cm-1 to 1780cm-1 is not less than 70% of the peak height of the infrared absorption peak in the wavenumber range of 1480cm-1 to 1570cm-1.

[0248] The modified polyol product obtained in this embodiment was mixed with PMDI at a weight ratio of 1:1 to prepare a cured polyurethane with uniform quality.

[0249] This modified polyol product can be used to manufacture rigid polyurethane foam.

[0250] Example G6

[0251] The difference between this embodiment and Embodiment G1 is as follows: Under nitrogen protection, ethylene glycol and the initial polyurethane are first mixed uniformly at 190°C and reacted for 8 hours. Then, the temperature is lowered to 120°C, maleic anhydride is added, and the mixture is stirred for 1 hour to obtain the degradation product. The reaction mixture is then filtered through a 60µm filter to obtain a filtrate and a filter cake containing the modified polyol product. The filter cake is dissolved in 10 times its volume of methanol and then filtered through slow-speed filter paper with a pore size of 13µm. The remaining solid on the filter paper is dried and weighed to be 55g. The hydroxyl value is 11 mg KOH / g, and the hydroxyl value is 105 mg KOH / g. It can be used as an active filler for polyols. The filtrate was distilled under reduced pressure to remove excess ethylene glycol, yielding 281 g of modified polyol product numbered MB1C. The viscosity is greater than 20000 mPa·s. It is a brown paste at room temperature. The initial polyurethane content in the modified polyol product is (200-55) / 281 = 51.6 wt%. The amine value is 54 mg KOH / g, and the hydroxyl value is 410 mg KOH / g.

[0252] The infrared spectrum of the MB1C-modified polyol product was measured according to the general rules of infrared spectroscopy analysis GB / T 6040, as follows: Figure 3 As shown in Table G6, the peak data of the infrared spectrum can be observed at 1680 cm⁻¹. -1 ~1780cm -1 1714.99 cm in the wavenumber range -1 A distinct absorption peak appears at 1090–1210 cm⁻¹. -1 1162.00 cm in the wavenumber range -1 It has a distinct single absorption peak at 1610 cm⁻¹. -1 and 1480cm -1 ~1570cm -1 1510cm in the wavenumber range -1 A distinct absorption peak also appeared nearby.

[0253] Table G6: Infrared spectral peak data of MB1C, a modified polyol product

[0254] Peak position 1162 strength 0.202 Peak position 1513.77 strength 0.204 Peak position 1602.36 strength 0.107 Peak position 1714.99 strength 0.219

[0255] As can be seen from Table G6, the height ratio of peak 1713.25 to peak 1513.07 is 1.07 / 1.

[0256] Example G7

[0257] The difference between this embodiment and Embodiment G2 is as follows: Under nitrogen protection, propylene glycol and the initial polyurethane are first mixed uniformly at 180°C and reacted for 6 hours. Then, the temperature is lowered to 120°C, succinic anhydride is added, and the mixture is stirred for 1 hour to obtain the degradation product. The reaction mixture is then filtered through a 60µm filter to obtain a filtrate and a filter cake containing the modified polyol product. The filter cake is dissolved in 10 times its volume of methanol and then filtered through slow-speed filter paper with a pore size of 13µm. The remaining solid on the filter paper is dried and weighed to be 30g. The hydroxyl value is 20 mg KOH / g, and the hydroxyl value is 170 mg KOH / g. It can be used as an active filler for polyols. The filtrate was distilled under reduced pressure to remove excess propylene glycol, yielding 265 g of modified polyol product numbered MB1. The viscosity is greater than 20000 mPa·s. It is a brown paste at room temperature. The initial polyurethane content in the modified polyol product is (200-30) / 265 = 64.2 wt%. The amine value is 51 mg KOH / g, and the hydroxyl value is 397 mg KOH / g.

[0258] The infrared spectrum of the modified polyol product of MB1 was measured according to the general rules of infrared spectroscopy analysis GB / T 6040, as follows: Figure 4 As shown in Table G7, the peak data of the infrared spectrum can be observed at 1680 cm⁻¹. -1 ~1780cm -1 1713.12 cm in the wavenumber range -1 A distinct absorption peak appears at 1090–1210 cm⁻¹. -1 1177.27 cm in the wavenumber range -1 It has a distinct single absorption peak at 1610 cm⁻¹. -1 and 1480cm -1 ~1570cm -1 1510cm in the wavenumber range -1 A distinct absorption peak also appeared nearby.

[0259] Table G7: Infrared spectral peak data of modified polyol product MB1

[0260] Peak position 1177.27 strength 0.234 Peak position 1513.15 strength 0.253 Peak position 1611.51 strength 0.132 Peak position 1713.12 strength 0.248

[0261] As can be seen from Table G7, the height ratio of peak 1713.25 to peak 1513.07 is 0.98 / 1.

[0262] Example G8

[0263] The difference between this embodiment and embodiment G3 is as follows: Under nitrogen protection, diethylene glycol and the initial polyurethane are first mixed uniformly at 210°C and reacted for 18 hours. Then, the temperature is lowered to 120°C, phthalic anhydride is added, and the mixture is stirred for 8 hours to obtain the degradation product. The reaction mixture is then filtered through a 60µm filter. The filter cake is dissolved in 10 times its volume of methanol and then filtered through a slow-speed filter paper with a pore size of 13µm. The remaining solid on the filter paper is dried and weighed to be 106g. The hydroxyl value of the filter cake is 21mgKOH / g (amine value) and 45mgKOH / g (hydroxyl value), which can be used as an active filler for polyols. The filtrate is distilled under reduced pressure to remove excess diethylene glycol, yielding 623g of degraded polyol with a viscosity greater than 20000mPa.s. It is a brown paste at room temperature. The initial polyurethane content in the modified polyol product is (600-106) / 623 = 79.3wt%. The amine value is measured to be 48mgKOH / g and the hydroxyl value to be 124mgKOH / g.

[0264] Example G9

[0265] Under nitrogen protection, 200 g of ethylene glycol and 200 g of NJ204 (hydroxyl value 280) were mixed and heated to 210 °C to obtain a degradation agent. Then, 300 g of polyurethane waste (recycled shoe sole material) was added to the degradation agent, and the mixture was heated and stirred for 6 hours until the polyurethane solid dissolved, maintaining the temperature at 210 °C to obtain a reaction mixture. The reaction mixture was then cooled to 80 °C, and 80 g of methyltetrahydrophthalic anhydride was added and stirred for 4 hours. The mixture was then filtered through a 60 μm filter and cooled to room temperature to obtain a filtrate containing the modified polyol product and a filter cake. The filter cake was dissolved in 10 times its volume of methanol and filtered through slow-speed filter paper with a pore size of 13 μm. The remaining solid on the filter paper was dried and weighed to be 75 g. The hydroxyl value of the filter cake was 16 mg KOH / g (amine value). The hydroxyl value is 95 mg KOH / g, which can be used as an active filler for polyols. The obtained filtrate, after removing excess ethylene glycol by vacuum distillation, yields 561 g of modified polyol product with a viscosity greater than 10000 mPa·s. It is a brown paste at room temperature. The initial polyurethane content in the modified polyol product is (300-75) / 561 = 40.1 wt%. The obtained product contains amide groups. According to DIN 53176, the amine value of this modified polyol product is 56 mg KOH / g, and the hydroxyl value is 189 mg KOH / g. The amine value of the modified polyol product in this embodiment is lower than that obtained by existing methods, indicating that the process optimization of this invention further reduces the amine value of the modified polyol product. The modified polyol product obtained in this embodiment is mixed with PMDI at a weight ratio of 1:1 to prepare a uniformly cured polyurethane.

[0266] Furthermore, the modified polyol product of this embodiment can have its infrared spectrum measured according to the general rules of infrared spectroscopy analysis GB / T6040. The modified polyol product has infrared absorption peaks in the wavenumber ranges of 1680cm-1 to 1780cm-1, 1480cm-1 to 1570cm-1, and 1100cm-1 to 1210cm-1, and the peak height of the infrared absorption peak in the wavenumber range of 1680cm-1 to 1780cm-1 is not less than 70% of the peak height of the infrared absorption peak in the wavenumber range of 1480cm-1 to 1570cm-1.

[0267] Example G10

[0268] Under nitrogen protection, 300 g of ethylene glycol, 300 g of propylene glycol, and 6 g of tetrabutyl titanate were mixed and heated to 190°C and stirred for 1 hour to dissolve evenly, yielding a degradation solution. Then, 200 g of polyurethane waste (recycled rigid building insulation foam waste) was added to the degradation solution, and the mixture was heated and stirred for 3 hours until the polyurethane solid dissolved, maintaining the temperature at 190°C. The reaction mixture was then cooled to 50°C, and 30 g of maleic anhydride, 20 g of succinic anhydride, and 30 g of phthalic acid were added and stirred for 6 hours. The mixture was then filtered through a 60 μm filter and cooled to room temperature, yielding a filtrate and filter cake containing the modified polyol product. The filter cake was dissolved in 10 times its volume of methanol and filtered through slow-speed filter paper with a pore size of 13 μm. The remaining solid on the filter paper was dried and weighed to be 38 g. The hydroxyl value of the filter cake was 1, and the amine value was 1. The modified polyol product, with a hydroxyl value of 156 mg KOH / g and a KOH concentration of 2 mg KOH / g, can be used as an active filler for polyols. The filtrate is distilled under reduced pressure to remove excess propylene glycol and ethylene glycol, yielding 236 g of modified polyol product. The viscosity is greater than 10000 mPa·s, and it is a brown paste at room temperature. The initial polyurethane content in the modified polyol product is (200-38) / 236 = 68.6 wt%. The product contains amide groups. According to DIN 53176, the amine value of this modified polyol product is 48 mg KOH / g, and the hydroxyl value is 390 mg KOH / g. The amine value of the modified polyol product in this embodiment is lower than that obtained by existing methods, indicating that the process optimization of this invention further reduces the amine value of the modified polyol product. The modified polyol product obtained in this embodiment is mixed with PMDI at a weight ratio of 1:1 to prepare a uniformly cured polyurethane.

[0269] Furthermore, the modified polyol product of this embodiment can have its infrared spectrum measured according to the general rules of infrared spectroscopy analysis GB / T6040. The modified polyol product has infrared absorption peaks in the wavenumber ranges of 1680cm-1 to 1780cm-1, 1480cm-1 to 1570cm-1, and 1100cm-1 to 1210cm-1, and the peak height of the infrared absorption peak in the wavenumber range of 1680cm-1 to 1780cm-1 is not less than 70% of the peak height of the infrared absorption peak in the wavenumber range of 1480cm-1 to 1570cm-1.

[0270] Comparative Example G1

[0271] Under nitrogen protection, 300 g of diethylene glycol was heated to 80°C, and then 600 g of polyurethane waste (recycled polyurethane flexible foam material) was added. The mixture was heated and stirred for 18 hours until the polyurethane solid dissolved, with the temperature maintained within the range of 210°C. The mixture was then cooled to 80°C, filtered through a 30 μm filter, and cooled to room temperature. The resulting filtrate was distilled under reduced pressure to remove excess diethylene glycol, yielding the modified polyol product. The modified polyol product had an amine value of 270 mg KOH / g and a hydroxyl value of 119 mg KOH / g.

[0272] Comparative Example G2

[0273] Under nitrogen protection, 800 g of ethylene glycol was heated to 50°C; then 200 g of polyurethane waste (recycled rigid foam waste from refrigerators) was added, and the mixture was heated and stirred for 16 hours until the polyurethane solid dissolved, maintaining the temperature within the range of 190°C; then cooled to 120°C, filtered through a 60 μm filter, and cooled to room temperature. The resulting filtrate was distilled under reduced pressure to remove excess ethylene glycol, yielding the modified polyol product. The modified polyol product was found to have an amine value of 235 mg KOH / g and a hydroxyl value of 537 mg KOH / g.

[0274] Comparative Example G3

[0275] Under nitrogen protection, 80 g of maleic anhydride, 28 g of water, and 800 g of ethylene glycol were mixed, then heated to 150°C and stirred for 90 minutes to dissolve evenly. Then, 200 g of polyurethane waste (recycled refrigerator rigid foam) was added, and the mixture was heated and stirred for 16 hours until the polyurethane solid dissolved, with the temperature maintained within the range of 160°C. The mixture was then cooled to 120°C and filtered through a filter (60 μm), but the filtration was very difficult and normal process operation could not be achieved.

[0276] Comparative Example G4

[0277] 80 g of maleic anhydride, 28 g of water, and 800 g of ethylene glycol were mixed and heated to 150 °C and stirred for 90 minutes until homogeneous. Then, 200 g of polyurethane waste (recycled refrigerator rigid foam) was added, and the mixture was heated and stirred for 20 hours until the polyurethane solid dissolved, maintaining the temperature within the range of 180 °C. The mixture was then cooled to 120 °C, and the reaction mixture was filtered through a 60 μm filter. If difficult to filter, it was filtered through a 300 μm filter and cooled to room temperature. The filtrate was distilled under reduced pressure to remove excess ethylene glycol, yielding the modified polyol product. According to DIN 53176, the amine value of the obtained modified polyol product was 19 mg KOH / g, and the hydroxyl value was 389 mg KOH / g.

[0278] Comparative Example G5

[0279] 80 g of maleic anhydride, 370 g of diethylene glycol, and 20 g of water were mixed and heated to 150 °C over 90 minutes while stirring to dissolve. Then, 400 g of polyurethane waste (recycled flexible polyurethane foam material) was added, and the mixture was heated and stirred for 16 hours until the polyurethane solid dissolved, maintaining the temperature within the range of 180 °C. Simultaneously, 20 g of water was added during the polyurethane solid dissolution process, followed by stirring for another hour. Then, 70 g of ethylene glycol was added, and the mixture was stirred at 220 °C for 1 hour. Next, 20 g of phthalic anhydride was added, and while stirring, 20 g of dipropylene glycol was added after 10 minutes. The mixture was stirred at 220 °C for another half hour, and then stirred until cooled to 80 °C to obtain the reaction mixture. The reaction mixture was filtered through a 60 μm filter, but filtration was very difficult, making normal process operation impossible.

[0280] Comparative Example G6

[0281] 80 g of maleic anhydride, 370 g of diethylene glycol, and 20 g of water were mixed and heated to 150 °C over 90 minutes while stirring to dissolve. Then, 400 g of polyurethane waste (recycled polyurethane flexible foam material) was added, and the mixture was heated and stirred for 25 hours until the polyurethane solid dissolved, with the temperature maintained at 210 °C. During the dissolution of the polyurethane solid, 20 g of water was added simultaneously. After stirring for another hour, 70 g of ethylene glycol was added, and the mixture was stirred at 220 °C for another hour. Next, 20 g of phthalic anhydride was added, and while stirring, 20 g of dipropylene glycol was added after 10 minutes. The mixture was stirred at 220 °C for another half hour, and then stirred until it cooled to 80 °C to obtain the reaction mixture. The reaction mixture was filtered through a 60µm filter. If it was difficult to filter, the reaction mixture was filtered through a 200µm filter. The filtrate was then distilled under reduced pressure to remove excess alcoholysis agent, thus obtaining the modified polyol product. According to DIN53176, the amine value of the obtained modified polyol product was determined to be 23 mgKOH / g, and the hydroxyl value was 95 mgKOH / g.

[0282] Comparing Examples G1-10 and Comparative Examples G1-2, it can be found that if acid anhydrides are not used in the degradation reaction, the amine value of the resulting alcoholysis-modified polyol product is too high. This results in the modified polyol product not only being toxic, but also reacting too quickly with isocyanates, leading to poor process operability and hindering subsequent formulation adjustments and product preparation.

[0283] Comparing Examples G1-9 and Comparative Examples G3-4, it can be found that although the addition of acid anhydride can effectively reduce the amine value of the modified polyol product, the reaction system with added water, even with the process flow increased as shown in Comparative Examples G5-6, still results in a modified polyol product with an excessively large particle size. In contrast, the small particle size of the modified polyol product in Examples G1-8 is beneficial for filtration during the production process and subsequent formulation operations.

[0284] Based on the method of this invention, the modified polyol product obtained from the degradation of polyurethane waste can be used as the degraded polyol. It can be mixed with ordinary polyol (i.e., polyols obtained by ring opening of ethylene oxide, propylene oxide or butane, or polyester polyols, etc.) in a weight ratio (degraded polyol / ordinary polyol) of 5 / 95 to 55 / 45 to prepare new polyurethane products. The performance of the new polyurethane products will not be significantly reduced compared to the original polyurethane products (i.e., without the addition of any recycled polyols).

[0285] Taking the modified polyol product obtained in Example G1 (measured hydroxyl value 360 ​​mg KOH / g) as an example, the degraded polyol obtained from the degradation reaction was mixed with ordinary polyol in a certain proportion to prepare rigid foam products, and the corresponding properties of the rigid foam were tested. The ordinary polyether polyol was selected from Jurong Ningwu NJ-303, 44V20 was selected from Covestro polymers, the catalysts PC-5, T9, and TMR-2 were selected from Air Products, cyclopentane was commercially available, and the surfactant was selected from Mester. Three products were prepared according to the proportions in Table G1-1.

[0286] Table G1-1: Formulation Ratios of Rigid Foam Products

[0287]

[0288] The physical properties of rigid foam products were tested based on the GBT40363-2021 standard. The specific results are shown in Table G1-2 below.

[0289] Table G1-2: Physical property test results of Examples H1-2 and comparative examples

[0290] Foam properties Example H1 Example H2 Comparative Examples Compressive strength (MPa) 0.35 0.32 0.33 Water absorption rate (%) 0.81 0.83 0.82 Thermal conductivity / (W / (mk)) 0.022 0.023 0.021

[0291] As can be seen from Table G1-2, the degraded polyols of Examples H1-2 can replace a portion of ordinary polyol products in the manufacture of new polyurethane products, and the physical properties they achieve are similar to those of existing ordinary polyol products. This fully realizes the utilization of recycled products in new products, helps to reduce production costs, further increases the advantages of waste recycling and treatment, and provides strong support for environmental protection.

[0292] The technical point of this invention is that polyurethane solids can be alcoholyzed by simply adding acid anhydride. The resulting modified polyol product has two advantages: (1) small particle size and easy filtration; (2) low amine value. This method effectively solves the problem of high amine value in traditional polyurethane alcoholysis methods. Although there are methods reported to add acid anhydride to reduce the amine value of polyurethane solid alcoholysis products, it often requires that the added acid anhydride be used in conjunction with water rather than alone. Furthermore, acid anhydride, water, polyol, and small molecule alcohol must be added gradually multiple times during the degradation process to achieve the purpose of reducing the amine value of the alcoholysis products. This not only increases the complexity of the process steps, but also results in a larger particle size of the degraded products, which is not conducive to separation and subsequent use.

[0293] This invention innovatively discovers that adding acid anhydride at the beginning of the alcoholysis process simplifies the process and directly reduces the amine value of the alcoholysis products. Furthermore, this invention eliminates the need for additional water. If acid anhydride and water are used together (Comparative Examples G3-6), the resulting modified polyol products have very large particle sizes, which is detrimental to separation and subsequent use.

[0294] The terminology and expressions used herein are for descriptive purposes only and this patent should not be limited to them. The use of these terms and expressions does not imply the exclusion of any illustrative and descriptive equivalent features (or parts thereof), and it should be recognized that various possible modifications should also be included within the scope of the claims. Other modifications, variations, and substitutions may also exist. Accordingly, the claims should be considered to cover all such equivalents.

[0295] Similarly, it should be noted that although this patent has been described with reference to the specific embodiments described above, those skilled in the art should recognize that the above embodiments are only used to illustrate this patent, and various equivalent changes or substitutions can be made without departing from the spirit of this patent. Therefore, any changes or modifications to the above embodiments within the essential spirit of this patent will fall within the scope of the claims of this patent.

Claims

1. A modified polyol product, characterized in that, The modified polyol product contains urethane molecule fragments and hydroxyl groups. According to the ASTM E1899-2016 method, the hydroxyl value of the modified polyol product is 5~800 mg KOH / g, and the amine value of the modified polyol product is 0~20, 20~30, 30~40, 40~50, 50~60 or 60~80 mg KOH / g. The amine value of the modified polyol product is not 0 mg KOH / g. The modified polyol product is obtained by degradation reaction of an initial polymer and a degrading agent; the weight ratio of polyurethane waste as the initial polymer to the degrading agent is 1: 0.5–1, 1:1–2, 1:2–4, or 1:4–8; the degradation agent comprises a polyol composition, wherein the polyol composition is a combination of a polyol and an anhydride, a carboxyl-containing compound, and / or a compound containing both a carboxyl and a hydroxyl group; The modified polyol product can be obtained by dissolving it in a solvent and filtering it through a 50-800 mesh sieve, wherein the solvent includes methanol and / or polyol; The preparation steps of the modified polyol product include: Step A1: The acid anhydride and the polyol are mixed and reacted to obtain the degradation agent. The mixing reaction does not involve the addition of water, hydrogen peroxide or free radical initiators. Step B1: Add the polyurethane waste to the degradation agent obtained in step A1, heat and mix to allow the polyurethane waste to undergo the degradation reaction, and obtain a reaction mixture containing the modified polyol product. The degradation reaction does not involve adding water, hydrogen peroxide or free radical initiators.

2. The modified polyol product according to claim 1, characterized in that, The modified polyol product contains R1-NH-CO-R2 groups.

3. The modified polyol product according to claim 2, characterized in that, According to the infrared spectroscopy test in GB / T 6040-2019, the modified polyol product was measured at 1680 cm⁻¹. -1 ~1780cm -1 1480cm -1 ~1570cm -1 and 1100 cm -1 ~1210cm -1 It exhibits an infrared absorption peak in the wavenumber range, and at 1680 cm⁻¹ -1 ~1780cm -1 The peak height of the infrared absorption peak in the wavenumber range is not lower than that at 1480 cm⁻¹. -1 ~1570cm -1 The peak value of the infrared absorption peak is 70% of the maximum value in the wavenumber range.

4. The modified polyol product according to claim 1, characterized in that, The peak distribution regions of the number-average molecular weight Mn of the modified polyol product, measured by both RID and VWD detectors, include 150~200, 200~350, 350~700, 700~1000, 1000~1800, 1800~3000, 3000~5000, 5000~10000, 10000~30000, and 30000~60000 g / mol, wherein the detection wavelength of the VWD detector is 254 nm.

5. The modified polyol product according to claim 1, characterized in that, The modified polyol product has a viscosity greater than 10000 mPa·s or is a solid at 25°C. The modified polyol product is in one or more of the following forms: paste, granules, flakes, powder, or strips. The particle size of the powder is not less than 50 μm.

6. The modified polyol product according to claim 1, characterized in that, The modified polyol product is dissolved in the solvent at a temperature of 40~150℃.

7. The modified polyol product according to claim 1, characterized in that, The modified polyol product is obtained by the following steps: Step A: Under nitrogen protection, the initial polymer is subjected to a degradation reaction with a degrading agent containing active groups to break at least a portion of the molecular chains of the initial polymer, thereby obtaining a modified polyol product containing molecular fragments of the initial polymer and the active groups. The initial polymer includes thermoplastic polymers with linear or branched molecular structures or thermosetting polymers with cross-linked network molecular structures, and the molecular weight of the initial polymer is not less than 10,000 g / mol. The initial polymer is the polyurethane waste; The degradation agent includes one or more combinations of polyols, acid anhydrides, compounds containing carboxyl groups, and compounds containing both carboxyl and hydroxyl groups; The degradation reaction time is 4~30 minutes, 0.5~2 hours, 2~3 hours, 3~6 hours, 6~12 hours, and 12~24 hours. The preparation steps of the modified polyol product include: Step A1: The acid anhydride and the polyol are mixed and reacted to obtain the degradation agent. The mixing reaction does not involve the addition of water, hydrogen peroxide or free radical initiators. Step B1: Add the polyurethane waste to the degradation agent obtained in step A1, heat and mix to allow the polyurethane waste to undergo the degradation reaction, and obtain a reaction mixture containing the modified polyol product. The degradation reaction does not involve adding water, hydrogen peroxide or free radical initiators.

8. The modified polyol product according to claim 7, characterized in that, The acid anhydride or the carboxyl-containing compound contains a double bond, and the acid anhydride includes maleic anhydride.

9. The modified polyol product according to claim 7, characterized in that, The modified polyol product contains an initial polyurethane component content of not less than 25% by weight.

10. A modified curable polyurethane, prepared by reacting the modified polyol product according to any one of claims 1 to 9 with a curing agent via a chain extender group.

11. The cured polyurethane according to claim 10, characterized in that, The chain extender group includes a hydroxyl group, and the curing agent contains a reactive functional group capable of reacting with the chain extender group. The reactive functional group includes one or more of the following: isocyanate group, acid anhydride, carboxyl group, epoxy group, amine group, amide group, or aldehyde group.

12. A method for manufacturing the modified polyol product according to any one of claims 1 to 9, comprising the following steps: Step A: The initial polymer is subjected to a degradation reaction with a degrading agent containing active groups to break at least a portion of the molecular chain of the initial polymer, thereby obtaining a modified polyol product containing molecular fragments of the initial polymer and the active groups; The initial polymer includes thermoplastic polymers with linear or branched molecular structures or thermosetting polymers with cross-linked network molecular structures, and the molecular weight of the initial polymer is not less than 10,000 g / mol. The initial polymer is the polyurethane waste. The degradation agent includes one or more combinations of polyols, acid anhydrides, compounds containing carboxyl groups, and compounds containing both carboxyl and hydroxyl groups; The degradation reaction does not involve the addition of water, hydrogen peroxide, or free radical initiators; The degradation reaction time is 4~30 minutes, 0.5~2 hours, 2~3 hours, 3~6 hours, 6~12 hours, and 12~24 hours. The degradation reaction temperature is 110–150℃, 150–170℃, 170–180℃, 180–200℃, 200–220℃, 220–250℃; Step A includes: Step A1: The acid anhydride and the polyol are mixed and reacted to obtain the degradation agent. The mixing reaction does not involve the addition of water, hydrogen peroxide or free radical initiators. Step B1: Add the polyurethane waste to the degradation agent obtained in step A1, heat and mix to allow the polyurethane waste to undergo the degradation reaction, and obtain a reaction mixture containing the modified polyol product. The degradation reaction does not involve adding water, hydrogen peroxide or free radical initiators. Step C1: Filter the reaction mixture obtained in step B1 to obtain a filtrate and a filter cake containing the modified polyol product.

13. The method for manufacturing the modified polyol product according to claim 12, characterized in that, The degradation agent is prepared by reacting polyols and acid anhydrides.

14. The method for manufacturing the modified polyol product according to claim 12, characterized in that, The polyol is a diol.

15. The method for manufacturing the modified polyol product according to claim 12 or 13, characterized in that, The acid anhydride or the carboxyl-containing compound contains a double bond, and the acid anhydride includes maleic anhydride.

16. The method for manufacturing the modified polyol product according to claim 12, characterized in that, Step A further includes: In step A1, the temperature of the mixing reaction is 30℃~140℃; the time of the mixing reaction is 30~480min. In step B1, the temperature of the degradation reaction is 110~250℃.

17. The use of a modified polyol product obtained by the manufacturing method according to any one of claims 12 to 16 in the preparation of rigid polyurethane foam.

18. The use of a modified polyol product obtained by the manufacturing method according to any one of claims 12 to 16 in the preparation of polyurethane flexible foam.

19. The use of a modified polyol product obtained by the manufacturing method according to any one of claims 12 to 16 in the preparation of polyurethane elastomers.

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