Low-temperature polyurethane sponge, preparation method and compound thereof

Abstract

The invention discloses a preparation method of polyurethane sponge. In particular to low-temperature polyurethane sponge, a preparation method and a compound thereof. The core part of the polyurethane sponge prepared by the preparation method disclosed by the invention does not have a'yellow core 'phenomenon, and the polyurethane sponge has excellent elongation at break and tensile strength.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer chemistry, and particularly relates to a low-temperature polyurethane sponge, a preparation method thereof, and a compound thereof. Background Art

[0002] Due to its excellent elasticity, energy absorption, and processing adaptability, polyurethane sponge has become a core material in fields such as home furnishing, automotive, and packaging. Its industrial production highly depends on the precise control of the foaming process. However, during the traditional foaming process, due to excessive internal temperature gradient or intense local reaction, the phenomenon of "yellow core" appears in the core part. This phenomenon not only shows abnormal yellowing of the internal color of the sponge but also causes oxidative degradation of molecular chains, resulting in deterioration of mechanical properties such as decreased resilience and increased compression set rate, severely limiting its application in scenarios with strict requirements for appearance and performance consistency, such as high-end electronic products and medical devices.

[0003] To improve the mechanical properties of the sponge, diamine chain extenders (such as ethylenediamine, MOCA) are widely used in the industry. Their amino groups can strengthen the crosslinking density of hard segments, significantly improving the tensile strength and tear strength. However, the high reactivity of diamine chain extenders will intensify the heat release of the system, promoting the oxidation of amino groups to form dark by-products (such as quinone compounds), which, together with the temperature gradient, instead become the core cause of the "yellow core" phenomenon. This contradiction between "enhanced mechanical properties" and "aggravated yellow core defects" has become a bottleneck restricting the large-scale application of high-strength polyurethane sponges.

[0004] The prior art mainly alleviates the yellow core problem by adjusting the foaming formula (such as reducing the catalyst concentration) or optimizing process parameters (such as segmented temperature control). However, such methods can only locally inhibit the degree of defects and cannot eradicate the essential contradiction between the generation of oxidative by-products and heat release imbalance, and are prone to reducing production efficiency or losing mechanical properties. Therefore, developing a new preparation technology that takes into account both the enhancement of mechanical properties and the eradication of the yellow core phenomenon is of urgent significance for breaking through the high-end application barriers and promoting industrial upgrading. Summary of the Invention

[0005] The present invention aims to solve the technical problem of the "yellow core" phenomenon in the core part during the preparation of polyurethane sponges. The present invention provides a low-temperature polyurethane sponge, a preparation method thereof, and a compound thereof. The polyurethane sponge prepared by the preparation method of the present invention will not have the "yellow core" phenomenon in the core part, and the polyurethane sponge has excellent elongation at break and tensile strength.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The present invention provides a preparation method of a low-temperature polyurethane sponge, which comprises the following steps: (1) Stir and mix polyether polyol, surfactant, chain extender, foaming agent, and catalyst evenly at room temperature to obtain a mixed solution.

[0008] (2) Add isocyanate to the mixture and stir at high speed to make it evenly mixed to obtain a mixture.

[0009] (3) Pour the mixture into a mold for foaming to obtain a polyurethane sponge; wherein the chain extender is .

[0010] In the present invention, the polyether polyol is polyether triol.

[0011] In the present invention, the polyether polyol is WANOL® F3156D.

[0012] In the present invention, the surfactant is a silicone surfactant.

[0013] In the present invention, the surfactant is Momentive Niax silicone L-595LE.

[0014] In the present invention, the blowing agent is water and / or dichloromethane.

[0015] In the present invention, the blowing agent is water.

[0016] In the present invention, the catalyst is triethylenediamine.

[0017] In the present invention, the catalyst is one or more of polyurethane catalyst A-1, polyurethane catalyst A-33, and polyurethane organotin catalyst T9.

[0018] In the present invention, the catalyst is polyurethane catalyst A-1, polyurethane catalyst A-33, and polyurethane organotin catalyst T9.

[0019] In the present invention, in the catalyst, the weight ratio of polyurethane catalyst A-1, polyurethane catalyst A-33, and polyurethane organotin catalyst T9 is 1:5:4.

[0020] In the present invention, the isocyanate is TDI80.

[0021] The present invention also provides a polyurethane sponge prepared by the above method for preparing a low-temperature polyurethane sponge.

[0022] The present invention also provides a compound, and the compound is .

[0023] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0024] The reagents and raw materials used in the present invention are all commercially available.

[0025] The positive and progressive effects of the present invention are as follows: The present invention provides a low-temperature polyurethane sponge, a preparation method thereof, and a compound. The polyurethane sponge prepared by the preparation method of the present invention will not show the phenomenon of "yellow core" in the core part; and the polyurethane sponge has excellent mechanical properties. Description of the Drawings

[0026] Figure 1 1H NMR spectrum of chain extender 1. Detailed Embodiments

[0027] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples. For the experimental methods without specific conditions in the following examples, they are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0028] Example 1 - Preparation of chain extender 1:

[0029] Di-tert-butyl carbonate (7.36 g, 33.74 mmol), compound 1 (5.0 g, 32.14 mmol), and 4-dimethylaminopyridine (0.4 g, 3.21 mmol) were added to a reaction flask, 200 mL of acetonitrile was poured in, and the mixture was stirred at 60 °C. The reaction was monitored by TLC until completion. The acetonitrile was removed under reduced pressure, then 100 mL of water was added, and the mixture was extracted with 3 × 300 mL of ethyl acetate to obtain an organic phase. The organic phase was washed with saturated brine, dried, and the solvent was removed to obtain a crude product. The crude product was purified by column chromatography with EA / PE = 8 / 2 (v / v) to obtain compound 2 (7.8 g, yield 94.9%).

[0030]

[0031] Under a nitrogen atmosphere, compound 2 (1.5 g, 5.87 mmol), 4-pyridinemethanamine (0.31 g, 2.86 mmol), and sodium triacetoxyborohydride (2.43 g, 11.45 mmol) were added to a reaction flask, and then 50 mL of ultra-dry 1,4-dioxane was added; the mixture was stirred at 60 °C. The reaction was monitored by TLC until completion. Then 50 mL of HCl solution (4 M) was added, and the mixture was stirred at 60 °C for 0.5 - 4 hours. Then it was cooled to room temperature, and the pH was adjusted to alkaline with NaOH solution. The reaction solution was allowed to stand and layer, and the organic phase was collected. The aqueous phase was extracted with 3 × 50 mL of ethyl acetate; the organic phases were combined. The combined organic phase was washed with saturated brine, dried, and the solvent was removed to obtain a crude product. The crude product was purified by column chromatography with EA / TEA = 97 / 3 (v / v) to obtain chain extender 1 (0.74 g, yield 66.8%).

[0032] 11H NMR (400 MHz, Chloroform-d) δ 8.54 – 8.48 (m, 2H), 7.34 – 7.28 (m,2H), 7.21 (dt, 2H), 7.12 (m, 2H), 6.79 (d, J = 8.0 Hz, 2H), 4.19 (br, 4H),3.89 (s, 2H), 3.70 (t, 4H).

[0033] HR-MS (ESI): Calculated for C 20 H 21 N4Cl2[M+H + 388.1216. Found: 388.1214.

[0034] Example 2 - 5: General method for preparing polyether-type polyurethane sponge.

[0035] S1: Stir and mix polyether polyol (WANOL® F3156D), surfactant, chain extender, foaming agent and catalyst evenly at room temperature to obtain a mixed solution.

[0036] S2: Add isocyanate to the mixed solution and stir at high speed (2000 - 3000 rpm; 8 - 20 s) to ensure uniform mixing to obtain a mixture.

[0037] S3: Pour the mixture into a mold and observe the appearance changes of the mixture as: translucent, fully turbid, white viscous liquid, foam growth, and foam growth stops. Then place the foam with stopped growth at room temperature in a shaded and ventilated environment for 5 - 7 days to obtain the polyether-type polyurethane sponge.

[0038] The polyether-type polyurethane sponges prepared in Examples 4 - 7 were formulated according to Table 1 below; and their properties were tested. Among them, the density of the polyurethane sponge was detected according to the GB / T6343 - 1995 standard, and the sample was taken from the core part of the sponge; the elongation at break and tensile strength were detected according to the GB / T6344 - 1996 standard; the tear strength was detected according to the GB / T10808 - 2006 standard.

[0039] The test method for the yellow core phenomenon is as follows: directly observe the appearance of the polyurethane sponge prepared in the above examples, or cut it open to observe the inside to see if there are phenomena such as "yellow", "tan" or even "black". Take samples of the same polyurethane sponge ten times; if at least one of the ten times shows phenomena such as "yellow", "tan" or even "black", the test result is recorded as "with yellow core"; if none of the ten times shows phenomena such as "yellow", "tan" or even "black", the test result is recorded as "without yellow core".

[0040] Testing method for the internal temperature of the sponge: In step S3 of the general method for preparing polyether-type polyurethane sponge, when the foam stops growing, quickly insert a thermometer into the interior of the foam and read the internal temperature of the foam. The specific test results are shown in Table 1: Table 1:

[0041] According to the experimental results of Examples 3-5, when diamine chain extenders (such as ethylenediamine or MOCA) are introduced, both the density and mechanical strength (tensile strength and tear strength) of the polyurethane sponge show an upward trend, but the elongation at break will decrease somewhat.

[0042] In addition, when diamine chain extenders (such as ethylenediamine or MOCA) are introduced, a phenomenon of yellow cores will occur. The possible reasons are that the reaction activity of the amino group (-NH2) in the diamine chain extender is higher than that of the polyol system with the isocyanate group (-NCO), resulting in an intensified local heat release in the reaction system, triggering a sudden rise in the internal temperature of the material, and then forming the "yellow core" phenomenon. In addition, the amino group is prone to oxidation reaction to generate dark by-products, which is also the reason for the formation of the "yellow core" phenomenon.

[0043] However, unexpectedly, when Chain Extender 1 is used, the density of the polyurethane sponge shows a slight decrease, the mechanical strength (tensile strength and tear strength) still remains improved, and there is no yellow core phenomenon in the material at all. The possible mechanism of this abnormal phenomenon lies in: the unique three-dimensional rigid molecular structure of Chain Extender 1 can effectively support the cell skeleton, promote the uniform distribution of cells and reduce the closed cell rate, thus offsetting the upward trend of density, and even causing a slight decrease in density due to the optimized cell volume; at the same time, the active amino groups in its molecular chain can still form a stable chemical cross-linking network with isocyanate to maintain the strengthening effect of mechanical strength.

Claims

1. A preparation method of a low-temperature polyurethane sponge, characterized in that, It comprises the following steps: (1) stirring and mixing polyether polyol, surfactant, chain extender, foaming agent and catalyst evenly at room temperature to obtain a mixed solution; (2) adding isocyanate to the mixed solution and stirring it at high speed to make it mix evenly to obtain a mixture; (3) pouring the mixture into a mold for foaming to obtain a polyurethane sponge; wherein, the chain extender is .

2. The preparation method of the low-temperature polyurethane sponge according to claim 1, characterized in that, The polyether polyol described is WANOL® F3156D.

3. The preparation method of the low-temperature polyurethane sponge according to claim 1, characterized in that, The surfactant described is a silicone surfactant.

4. The preparation method of the low-temperature polyurethane sponge according to claim 1, characterized in that, The blowing agent described is water.

5. The preparation method of the low-temperature polyurethane sponge according to claim 3, characterized in that, The surfactant described is Momentive Niax silicone L-595LE.

6. The preparation method of the low-temperature polyurethane sponge according to claim 1, characterized in that, The catalyst is one or more of polyurethane catalyst A-1, polyurethane catalyst A-33, and polyurethane organotin catalyst T9.

7. The preparation method of the low-temperature polyurethane sponge according to claim 6, characterized in that, The catalyst is polyurethane catalyst A-1, polyurethane catalyst A-33, and polyurethane organotin catalyst T9, wherein the weight ratio of polyurethane catalyst A-1, polyurethane catalyst A-33, and polyurethane organotin catalyst T9 is 1:5:

4.

8. The preparation method of the low-temperature polyurethane sponge according to claim 1, characterized in that, The isocyanate is TDI80.

9. A polyurethane sponge prepared by a method for preparing a low-temperature polyurethane sponge according to any one of claims 1-8.

10. A compound, characterized in that, The compound is .

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