A method for preparing waste PET polyether polyol, slow rebound sponge and its preparation

Abstract

This invention relates to the field of slow rebound foam technology, and particularly to a slow rebound foam based on waste PET polyether polyol, and its preparation method. The waste PET-based polyether polyol is obtained from bis(2-hydroxyethyl) terephthalamide obtained by aminolysis of waste PET as a starting material. This not only enables the recycling and reuse of waste PET, but also allows it to be used as a foaming material for slow rebound foam. The composite polyether is composed of polyether polyol I, polyether polyol II, waste PET-based polyether polyol, and polymer polyol. By adjusting and controlling parameters such as functionality, molecular weight, hydroxyl value, viscosity, and propylene oxide content of the waste PET-based polyether polyol, it can be stably stored at room temperature without crystallization. When used as the soft segment of slow rebound foam, it significantly improves the low-temperature resistance of the slow rebound foam, avoiding the problems of slow rebound polyurethane foam hardening and becoming difficult to cut in winter, as well as poor resilience.

Description

Technical Field

[0001] This invention relates to the field of slow rebound sponge technology, and in particular to a slow rebound sponge based on waste PET polyether polyol, and a preparation method thereof. Background Technology

[0002] Slow rebound foam undergoes plastic deformation under external pressure and does not immediately recover its original shape. Due to its many excellent properties, such as sound insulation, shock absorption, energy absorption, and a pleasant feel, it has been widely used in recent years in fields such as home furnishings, medical equipment, toys, and noise reduction. However, because slow rebound foam hardens at low temperatures, it loses its original comfort when used in products such as mattresses, pillows, and chairs during winter. The unique phase separation degree and glass transition temperature of slow rebound foam give it viscoelasticity. The glass transition temperature of traditional slow rebound foam is generally around 25°C, making it quite sensitive to temperature. To ensure that slow rebound foam remains soft at low temperatures, introducing polyether polyols, which are softer at low temperatures, into its soft segments is key to improving its low-temperature resistance.

[0003] Polyethylene terephthalate (PET) is one of the world's top five engineering plastics. With the continuous growth in its use in packaging, clothing, building materials, and biomedicine, improper disposal of waste PET can lead to resource waste and environmental pollution. Therefore, in the context of a "dual carbon" environment, the recycling and reuse of waste PET has become extremely important. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for recycling and reusing waste PET, which overcomes the problems of slow rebound polyurethane foam in the prior art, such as temperature sensitivity, hardening and difficulty in cutting in winter, and poor rebound. This method is based on waste PET polyether polyol, slow rebound foam and preparation method.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a polyol based on waste PET polyether, the innovation of which lies in:

[0006] The waste PET-based polyether polyol is obtained by using bis(2-hydroxyethyl) terephthalamide obtained from the aminolysis of waste PET as a starting material, and then carrying out a two-step ring-opening polymerization with ε-decanoic acid lactone and propylene oxide in sequence. Its molecular structure is shown below:

[0007] ,

[0008] Where m is 1 to 5 and n is 5 to 20.

[0009] Furthermore, the waste PET polyether polyol has a functionality of 2, a molecular weight of 800-2000, a hydroxyl value of 45-110, and a viscosity of 130-250.

[0010] Furthermore, in the waste PET polyether polyol, the mass percentage of bis(2-hydroxyethyl) terephthalamide is 5-15%, the mass percentage of ε-decyl lactone is 50-80%, and the mass percentage of propylene oxide is 5-50%.

[0011] A slow-rebound sponge, comprising the aforementioned waste PET polyether polyol, is innovative in that its raw materials, calculated by mass parts, include:

[0012] 60–90 parts of polyether blend, 0.05–3 parts of foam stabilizer, 0–1.0 parts of chain extender, 0.05–2 parts of reactive composite catalyst, 1–4.5 parts of water, and 40–80 parts of isocyanate.

[0013] The composite polyether is composed of polyether polyol I, polyether polyol II, polyether polyol based on waste PET, and polymer polyol.

[0014] Furthermore, the mass fraction ratio of each material in the combined polyether is: 5-20 parts polyether polyol I, 50-80 parts polyether polyol II, 5-15 parts polyether polyol based on waste PET, and 0-20 parts polymer polyol.

[0015] Furthermore, the polyether polyol I has a functionality of 3, a molecular weight of 1500-3000, a hydroxyl value of 50-60, and a viscosity of 450-800.

[0016] The polyether polyol II has a functionality of 3, a molecular weight of 3000-5000, a hydroxyl value of 30-50, and a viscosity of 900-1100.

[0017] The polymer polyol has a functionality of 1.5 to 2.5, a molecular weight of 2000 to 3000, a hydroxyl value of 25 to 40, and a viscosity of 3000 to 4500.

[0018] Furthermore, the foam stabilizer is one or a combination of two of the following: an organosilicon foam stabilizer or a polysiloxane-polyoxyolefin block copolymer;

[0019] The chain extender is a small molecule diamine compound;

[0020] The reactive composite catalyst is one or a combination of two types of tin-based catalysts or amine catalysts;

[0021] The isocyanate is 4,4'-diphenylmethane diisocyanate.

[0022] The method for preparing the slow-rebound sponge specifically includes the following steps:

[0023] (1) The polyether, foam stabilizer, chain extender, reactive composite catalyst, water and isocyanate are made into polymer raw materials and fed into the foaming machine. The foaming machine head performs open continuous low-pressure flat foaming. A conveyor belt is set on the rear side of the foaming machine's drop plate, and kraft paper is also laid on the drop plate.

[0024] (2) The sponge is sprayed onto the kraft paper at a speed of 80-400 kg / min using a foaming nozzle, and the kraft paper moves forward with the conveyor belt at a speed of 2-6 m / min, thereby driving the sponge to move forward together, realizing foaming and conveying at the same time.

[0025] The advantages of this invention are:

[0026] 1. In this invention, by adjusting and controlling parameters such as functionality, molecular weight, hydroxyl value, viscosity and propylene oxide content of waste PET polyether polyol, it can be stored stably at room temperature without crystallization. When used as the soft segment of slow rebound sponge, it can significantly improve the low temperature resistance of slow rebound sponge and avoid the problems of slow rebound polyurethane sponge hardening and being difficult to cut in winter and having poor rebound.

[0027] 2. In this invention, by adjusting the mass fraction ratio of the combined polyether, the physical properties of the slow rebound sponge, such as comfort, tensile strength, tear strength, and elongation at break, can be optimized; and part of the raw materials of the component of the combined polyether - the polyether polyol based on waste PET - are obtained from waste PFT, realizing the recycling and reuse of waste PET.

[0028] 3. The waste PET-based polyether polyol provided in this invention is obtained by using bis(2-hydroxyethyl) terephthalamide obtained from the aminolysis of waste PET as the starting material, and sequentially performing a two-step ring-opening polymerization with ε-decyl lactone and propylene oxide. It can not only realize the recycling and reuse of waste PET, but also be used as a foaming material for slow rebound sponge. Detailed Implementation

[0029] To further illustrate the technical means and effects of the present invention in achieving the intended purpose, the following are preferred embodiments, and the specific implementation methods, structures, features and effects of the present invention will be described in detail below.

[0030] The main raw material sources of this invention are as follows; other raw materials are all commercially available unless otherwise specified.

[0031] The polyether polyol based on waste PET is obtained by first using bis(2-hydroxyethyl) terephthalamide obtained from the aminolysis of waste PET as the starting material, and then performing a two-step ring-opening polymerization with ε-decyl lactone and propylene oxide in sequence. The mass percentage of bis(2-hydroxyethyl) terephthalamide is 5-15%, the mass percentage of ε-decyl lactone is 50-80%, and the mass percentage of propylene oxide is 5-50%.

[0032] The molecular structure of waste PET polyether polyol is shown below:

[0033] ,

[0034] Where: m is 1 to 5, and n is 5 to 20;

[0035] Based on waste PET polyether polyols with a functionality of 2, a molecular weight of 800–2000, a hydroxyl value of 45–110, and a viscosity of 130–250.

[0036] Polyether polyol A based on waste PET:

[0037] Take 8% by mass of bis(2-hydroxyethyl) terephthalamide, 77% of ε-decyl lactone, and 15% of propylene oxide to obtain a polyol A based on waste PET polyether with a functionality of 2, a molecular weight of 1000, a hydroxyl value of 78, and a viscosity of 187.

[0038] Polyether polyol B based on waste PET:

[0039] Take 8% by mass of bis(2-hydroxyethyl) terephthalamide, 67% of ε-decyl lactone, and 25% of propylene oxide to obtain polyol B based on waste PET polyether with a functionality of 2, a molecular weight of 1200, a hydroxyl value of 84, and a viscosity of 159.

[0040] Polyether polyol C based on waste PET:

[0041] Take 8% by mass of bis(2-hydroxyethyl) terephthalamide, 52% of ε-decyl lactone, and 40% of propylene oxide to obtain a polyether polyol C based on waste PET with a functionality of 2, a molecular weight of 1500, a hydroxyl value of 93, and a viscosity of 142.

[0042] Polyether polyol D based on waste PET:

[0043] A polyether polyol D based on waste PET was obtained by taking 15% bis(2-hydroxyethyl) terephthalamide, 80% ε-decyl lactone, and 5% propylene oxide, with a functionality of 2, a molecular weight of 1800, a hydroxyl value of 53, and a viscosity of 206.

[0044] A slow-rebound sponge, the raw materials of which, by weight, include:

[0045] 60–90 parts of polyether blend, 0.05–3 parts of foam stabilizer, 0–1.0 parts of chain extender, 0.05–2 parts of reactive composite catalyst, 1–4.5 parts of water, and 40–80 parts of isocyanate.

[0046] The polyether complex is composed of polyether polyol I, polyether polyol II, polyether polyol based on waste PET, and polymer polyol, with the following mass fraction ratio: 5-20 parts polyether polyol I, 50-80 parts polyether polyol II, 5-15 parts polyether polyol based on waste PET, and 0-20 parts polymer polyol.

[0047] Polyether polyol I has a functionality of 3, a molecular weight of 1500-3000, a hydroxyl value of 50-60, and a viscosity of 450-800.

[0048] Polyether polyol II has a functionality of 3, a molecular weight of 3000-5000, a hydroxyl value of 30-50, and a viscosity of 900-1100.

[0049] The polymer polyol has a functionality of 1.5–2.5, a molecular weight of 2000–3000, a hydroxyl value of 25–40, and a viscosity of 3000–4500.

[0050] The foam stabilizer is one or a combination of two of the following: organosilicon foam stabilizers or polysiloxane-polyoxyolefin block copolymers;

[0051] The chain extender is a small molecule diamine compound;

[0052] The reactive composite catalyst is one or a combination of two types of tin-based catalysts or amine catalysts;

[0053] The isocyanate is 4,4'-diphenylmethane diisocyanate.

[0054] The preparation method of slow rebound sponge specifically includes the following steps:

[0055] (1) The polyether, foam stabilizer, chain extender, reactive composite catalyst, water and isocyanate are made into polymer raw materials and fed into the foaming machine. The foaming machine head performs open continuous low-pressure flat foaming. A conveyor belt is set on the rear side of the foaming machine's drop plate, and kraft paper is also laid on the drop plate.

[0056] (2) The sponge is sprayed onto the kraft paper at a speed of 80-400 kg / min using a foaming nozzle, and the kraft paper moves forward with the conveyor belt at a speed of 2-6 m / min, thereby driving the sponge to move forward together, realizing foaming and conveying at the same time.

[0057] Example 1

[0058] Based on mass parts, 5 parts of polyether polyol I, 80 parts of polyether polyol II, 10 parts of waste PET-based polyether polyol A, 5 parts of polymer polyol, 50 parts of isocyanate, 1.5 parts of silicone foam stabilizer, 0.2 parts of chain extender, 0.4 parts of amine catalyst, and 2.5 parts of water were taken respectively. Polyether polyol I, polyether polyol II, waste PET-based polyether polyol A, polymer polyol, and isocyanate were first mixed to prepare a composite polyether.

[0059] Among them, polyether polyol I has a functionality of 3, a molecular weight of 200, a hydroxyl value of 55, and a viscosity of 580.

[0060] Polyether polyol II, functionality 3, molecular weight 3000, hydroxyl value 42, viscosity 1055;

[0061] The polymer polyol has a functionality of 1.5–2.5, a molecular weight of 3000, a hydroxyl value of 38, and a viscosity of 3300.

[0062] The chain extender is a low-molecular-weight diamine compound;

[0063] The foam stabilizer is an organosilicon foam stabilizer;

[0064] The reactive composite catalyst is an amine catalyst;

[0065] The isocyanate is 4,4'-diphenylmethane diisocyanate.

[0066] At room temperature, the aforementioned combined polyether, silicone foam stabilizer, chain extender, amine catalyst, water, and isocyanate are used to prepare polymerization raw materials. The raw materials are then transported to a foaming machine via pipeline. The foaming machine head performs open, continuous, low-pressure flat foaming. A conveyor belt is installed behind the landing plate of the foaming machine, and kraft paper is laid on the landing plate. The polymerized material is sprayed onto the kraft paper through the foaming nozzles of the foaming machine. The flow rate of the material sprayed from the foaming nozzles is controlled at 80 kg / min. The kraft paper moves forward with the conveyor belt at a speed of 2 m / min, thereby moving the sponge forward together, achieving simultaneous foaming and conveying.

[0067] Example 2

[0068] The difference between this embodiment and Example 1 is that the mass fractions of each component in the combined polyether are as follows: 5 parts of polyether polyol I, 85 parts of polyether polyol II, 5 parts of waste PET-based polyether polyol A, 5 parts of polymer polyol, 50 parts of isocyanate, 1.5 parts of silicone foam stabilizer, 0.2 parts of chain extender, 0.4 parts of amine catalyst, and 2.5 parts of water.

[0069] Example 3

[0070] The difference between this embodiment and Example 1 is that the mass fractions of each component in the combined polyether are as follows: 5 parts of polyether polyol I, 75 parts of polyether polyol II, 15 parts of waste PET-based polyether polyol A, 5 parts of polymer polyol, 50 parts of isocyanate, 1.5 parts of silicone foam stabilizer, 0.2 parts of chain extender, 0.4 parts of amine catalyst, and 2.5 parts of water.

[0071] Example 4

[0072] The difference between this embodiment and Example 1 is that the mass fractions of each component in the combined polyether are as follows: 5 parts of polyether polyol I, 75 parts of polyether polyol II, 10 parts of waste PET-based polyether polyol A, 50 parts of isocyanate, 1.5 parts of silicone foam stabilizer, 0.2 parts of chain extender, 0.4 parts of amine catalyst, and 2.5 parts of water.

[0073] Example 5

[0074] The difference between this embodiment and Example 1 is that waste PET polyether polyol B replaces waste PET polyether polyol A in the polymerization raw materials. The mass parts of each component are as follows: 5 parts of polyether polyol I, 80 parts of polyether polyol II, 10 parts of waste PET polyether polyol B, 5 parts of polymer polyol, 50 parts of isocyanate, 1.5 parts of silicone foam stabilizer, 0.2 parts of chain extender, 0.4 parts of amine catalyst, and 2.5 parts of water.

[0075] Example 6

[0076] The difference between this embodiment and Example 1 is that waste PET polyether polyol C is used instead of waste PET polyether polyol A in the polymerization raw materials. The mass parts of each component are as follows: 5 parts of polyether polyol I, 80 parts of polyether polyol II, 10 parts of waste PET polyether polyol C, 5 parts of polymer polyol, 50 parts of isocyanate, 1.5 parts of silicone foam stabilizer, 0.2 parts of chain extender, 0.4 parts of amine catalyst, and 2.5 parts of water.

[0077] Example 7

[0078] The difference between this embodiment and Example 1 is that waste PET polyether polyol D is used instead of waste PET polyether polyol A in the polymerization raw materials. The mass parts of each component are as follows: 5 parts of polyether polyol I, 80 parts of polyether polyol II, 10 parts of waste PET polyether polyol D, 5 parts of polymer polyol, 50 parts of isocyanate, 1.5 parts of silicone foam stabilizer, 0.2 parts of chain extender, 0.4 parts of amine catalyst, and 2.5 parts of water.

[0079] Comparative Example 1

[0080] The difference between this embodiment and Example 1 is that the mass fractions of each component in the polyether combination are as follows: 5 parts of polyether polyol I, 90 parts of polyether polyol II, 5 parts of polymer polyol, 50 parts of isocyanate, 1.5 parts of silicone foam stabilizer, 0.2 parts of chain extender, 0.4 parts of amine catalyst, and 2.5 parts of water.

[0081] Comparative Example 2

[0082] Chinese patent CN116265503B discloses a low-temperature responsive slow-rebound sponge.

[0083] Comparative Example 3

[0084] Chinese patent CN113583205B discloses a slow rebound sponge.

[0085] Comparative Example 4

[0086] Chinese patent CN113999363B discloses a high load-bearing, low-temperature insensitive, slow-rebound sponge.

[0087] Comparative Example 5

[0088] Chinese patent CN111269375B discloses a low-temperature responsive, inflatable, molded slow-rebound sponge.

[0089] Comparative Example 6

[0090] Slow rebound sponge that is normally available on the market.

[0091] The performance of the slow rebound sponges prepared in Examples 1-7 and Comparative Examples 1 and 6 was characterized. The physical properties of the slow rebound sponges were tested at room temperature according to the GB / T24451-2020 test standard. The hardness change and compression rebound performance of the slow rebound sponges were tested at 25 ℃ and -5 ℃ using an Asker C-type hardness tester according to the SRIS0101 standard. The compression results were taken according to the GB / T6669-2008 test standard. The test data are shown in Table 1 below.

[0092] temperature <![CDATA[25 o C]]> <![CDATA[25 o C]]> <![CDATA[25 o C]]> <![CDATA[25 o C]]> <![CDATA[25 o C]]> <![CDATA[-5 o C]]> <![CDATA[25 o C]]> <![CDATA[-5 o C]]> <![CDATA[25 o C]]> <![CDATA[-5 o C]]> Test Project <![CDATA[Density (g / cm 3 )]]> Tensile strength (kPa) Tear strength (N / m) Elongation (%) Hardness C Hardness C Recovery time (s) Recovery time (s) Compression rebound rate (%) Compression rebound rate (%) Example 1 38.3 122 2.1 312 9.8 11.2 4.1 7.6 4.5 6.4 Example 2 37.7 115 2.3 307 10.2 10.6 4.1 7.2 4.7 6.7 Example 3 39.5 138 2.5 324 10.1 11.5 4.4 7.7 4.6 7.1 Example 4 37.7 125 2.5 310 9.8 10.9 4.2 7.4 4.4 6.3 Example 5 38.2 123 2.6 306 9.6 10.7 4.3 7.2 4.9 6.6 Example 6 38.5 118 2.6 301 9.3 10.4 4.4 7.5 4.3 6.5 Example 7 38.1 142 2.7 341 10.2 11.7 4.5 7.8 4.7 6.8 Comparative Example 1 37.7 63 1.1 121 10.9 19.8 5.1 10.2 11.4 19.3 Comparative Example 2 49.2 － － － 185.98 206.22 4.7 － － － Comparative Example 3 － 76.2 187.4 231.1 － － － － － － Comparative Example 4 35 － － － － － 5 － 11.4 － Comparative Example 5 59.9 111 4 107 5.5 － 6.5 － Comparative Example 6 37.1 57 1.2 119 10.7 19 4 10 10 19

[0093] Table 1. Test data of physical properties of slow rebound sponge

[0094] As can be seen from the test data in Table 1, the slow rebound sponges prepared using Examples 1 to 7 all meet the national standards and are qualified products.

[0095] Comparative Example 1 is a common low-temperature resistant slow-rebound sponge formula.

[0096] Comparing Examples 1-3 with Comparative Example 6, it can be seen that when waste PET polyether polyol A is used as the soft segment introduction, it has little effect on the density of the slow rebound sponge and the recovery time at 25°C and -5°C. The tensile strength, tear strength, and elongation gradually increase with the increase of the mass fraction of waste PET polyether polyol A, and are all better than the slow rebound sponges that are normally available on the market. This is because the ester group and benzene ring structure in waste PET polyether polyol A can significantly improve the mechanical properties of the slow rebound sponge. On the other hand, the introduction of waste PET polyether polyol can significantly improve the hardness, recovery time, and compression recovery rate of the slow rebound sponge at 25°C and -5°C.

[0097] Comparing Examples 1 with Examples 5-7, it can be seen that when the proportion of propylene oxide in waste PET polyether polyol increases, the mechanical properties of slow rebound sponge will decrease, while the chain segment flexibility will increase.

[0098] Comparing Examples 1-7 with Comparative Example 1, it can be seen that the introduction of waste PET polyether polyol directly affects various properties of slow rebound sponge.

[0099] Comparing Examples 1-7 with Comparative Examples 2-5, it can be seen that the slow rebound sponge prepared using this method has better mechanical properties, as well as hardness, recovery time and compression rebound rate at 25℃ and -5℃ than the disclosed slow rebound sponge, thus solving the problem of slow rebound sponge hardening and reduced rebound performance in winter.

[0100] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A polyol based on waste PET polyether, characterized in that: The waste PET-based polyether polyol is obtained by using bis(2-hydroxyethyl) terephthalamide obtained from the aminolysis of waste PET as a starting material, and then carrying out a two-step ring-opening polymerization with ε-decanoic acid lactone and propylene oxide in sequence. Its molecular structure is shown below: , Where: m is 1 to 5, and n is 5 to 20; The waste PET polyether polyol has a functionality of 2, a molecular weight of 800-2000, a hydroxyl value of 45-110, and a viscosity of 130-250. The total amount of each component in the waste PET polyether polyol is 100%, with bis(2-hydroxyethyl) terephthalamide accounting for 5-15% by mass, ε-decyl lactone accounting for 50-80% by mass, and propylene oxide accounting for 5-50% by mass.

2. A slow-rebound sponge, comprising the waste PET polyether polyol as described in claim 1, characterized in that: Its raw materials, calculated by mass parts, include: 60–90 parts of polyether blend, 0.05–3 parts of foam stabilizer, 0–1.0 parts of chain extender, 0.05–2 parts of reactive composite catalyst, 1–4.5 parts of water, and 40–80 parts of isocyanate. The composite polyether is composed of polyether polyol I, polyether polyol II, polyether polyol based on waste PET, and polymer polyol; The mass fraction ratio of each material in the polyether combination is: 5-20 parts polyether polyol I, 50-80 parts polyether polyol II, 5-15 parts polyether polyol based on waste PET, and 0-20 parts polymer polyol. The polyether polyol I has a functionality of 3, a molecular weight of 1500-3000, a hydroxyl value of 50-60, and a viscosity of 450-800. The polyether polyol II has a functionality of 3, a molecular weight of 3000-5000, a hydroxyl value of 30-50, and a viscosity of 900-1100. The polymer polyol has a functionality of 1.5 to 2.5, a molecular weight of 2000 to 3000, a hydroxyl value of 25 to 40, and a viscosity of 3000 to 4500.

3. The slow rebound sponge according to claim 2, characterized in that: The foam stabilizer is one or a combination of two of the following: an organosilicon foam stabilizer or a polysiloxane-polyoxyolefin block copolymer. The chain extender is a small molecule diamine compound; The reactive composite catalyst is one or a combination of two types of tin-based catalysts or amine catalysts; The isocyanate is 4,4'-diphenylmethane diisocyanate.

4. The method for preparing slow-rebound sponge according to any one of claims 2 to 3, characterized in that: Specifically, the following steps are included: (1) Polymer raw materials are prepared by combining polyether, foam stabilizer, chain extender, reactive composite catalyst, water and isocyanate, and the raw materials are fed into a foaming machine. The foaming machine head performs open continuous low-pressure flat foaming, and a conveyor belt is set on the rear side of the foaming machine's drop plate. Kraft paper is also laid on the drop plate; (2) The foaming nozzle sprays the sponge onto the kraft paper at a speed of 80-400 kg / min, and the kraft paper moves forward with the conveyor belt at a speed of 2-6 m / min, thereby driving the sponge to move forward together, realizing foaming and conveying at the same time.

Images