Modified isocyanate as well as preparation method and application thereof

Abstract

The invention discloses modified isocyanate as well as a preparation method and application thereof, and the modified isocyanate is prepared from the following components in parts by weight: 25 to 30 parts of polyether polyol, 14 to 50 parts of polyether carbonate polyol, 0.003 to 0.01 part of polymerization inhibitor and 40 to 61 parts of isocyanate. The modified isocyanate is a mixture of an NCO group terminated modified isocyanate prepolymer and isocyanate, and the NCO group terminated modified isocyanate prepolymer is prepared by reacting polyether polyol, polyether carbonate polyol and isocyanate. The polyether polyol, the polyether carbonate polyol and the isocyanate are pre-polymerized, prepolymers are rich in variety, large in molecular weight and large in molecular weight distribution width, the molecular structures of the prepolymers are richer and comprise long-chain type and star type molecular structures, and the rebound resilience of the polyurethane elastomer is greatly improved; the resilience rate of the prepared polyurethane elastomer is up to 80% or above, and the resilience rate retainability is high after heat aging resistance and ultraviolet ray resistance tests; the process is simple and easy for industrial production.

Description

Technical Field

[0001] The present invention relates to a polyurethane elastomer material, and particularly to a modified isocyanate capable of improving the high resilience and aging resistance of polyurethane elastomers and a preparation method thereof. Background Art

[0002] Polyurethane is a general term for macromolecular compounds containing repeating urethane groups in the main chain, and is a polymer compound obtained by the interaction of isocyanates and polyol compounds. High-resilience polyurethane is a polyurethane polymer with an open-cell structure, belonging to soft polyurethane foam materials, and is one of the polyurethane products with a large consumption. As an important raw material for preparing polyurethane materials, isocyanates also have some problems: 1. When used directly, the reaction activity is too high and difficult to control; 2. The rebound performance of the prepared polyurethane material is poor; 3. The aging resistance and durability of the material are poor; 4. Free monomers are volatile and harmful to human health, etc. In view of the above deficiencies, in the prior art, polyols and isocyanates are pre-polymerized to improve the low-temperature storage property of isocyanates, enhance the process tolerance during use, and the various physical properties of polyurethane elastomers. The patent document with the publication number CN117304676A discloses a highly weather-resistant polyurethane elastomer and a preparation method thereof, and studied the preparation of highly weather-resistant polyurethane elastomers after pre-polymerization of different polyols and isocyanates, but the improvement of the resilience of the elastomer is not much. Resilience refers to the ability of a material to return to its original state after being deformed by force, and is also an important index for measuring the performance of elastomers. High resilience plays a crucial role in improving the comfort of material use, increasing the durability of materials, vibration isolation and noise reduction, and absorbing and releasing energy, etc., and is the direction of continuous improvement of polyurethane elastomer materials. Summary of the Invention

[0003] Object of the Invention: The object of the present invention is to improve the resilience and aging resistance of polyurethane elastomers, and provide a modified isocyanate; another object of the present invention is to provide a preparation method of the above-mentioned modified isocyanate and its application in high-resilience products.

[0004] Technical Solution: The modified isocyanate of the present invention, in parts by weight, comprises 25-30 parts of polyether polyol, 14-50 parts of polyether carbonate polyol, 0.003-0.01 part of polymerization inhibitor, and 40-61 parts of isocyanate; the modified isocyanate is a mixture of an NCO group-terminated modified isocyanate prepolymer prepared by reacting polyether polyol and polyether carbonate polyol with isocyanate and isocyanate.

[0005] Furthermore, the NCO content of the modified isocyanate prepolymer is 10-18%. The modified isocyanate prepolymer includes an NCO-terminated modified isocyanate prepolymer obtained by reacting a polyether polyol with an isocyanate, an NCO-terminated modified isocyanate prepolymer obtained by reacting a polyether carbonate polyol with an isocyanate, and an NCO-terminated modified isocyanate prepolymer obtained by reacting a polyether polyol and a polyether carbonate polyol with an isocyanate. Too low an NCO content can affect the reactivity, thereby affecting the curing time of the product, and can also affect the crosslinking density, leading to decreased mechanical properties of the product, poor elasticity and toughness, and failure to meet the requirements; too high an NCO content can make the reaction difficult to control, resulting in problems such as gelation and sudden polymerization, reduced product flexibility, and the possibility of cracking and breakage in actual applications. Too high an NCO content can also lead to poor storage stability of the modified isocyanate, reduced product quality, and increased manufacturing costs. The molecular chain of polyether carbonate polyol contains polyether segments and carbonate segments. The polyether segments have good flexibility, can rotate and bend freely, and can change conformation under the action of external force, making the material easy to deform, while the carbonate segments have a certain rigidity, which gives the material a certain strength and stability. The combination of the two gives the material good resilience; due to the molecular structure characteristics of polyether carbonate polyol, the carbonate group and ether bond structure in the main chain are relatively stable and have the ability to resist damage from ultraviolet rays; the strong rigidity of the carbonate group combined with the flexibility of the polyether segment can enhance the material's impact resistance and fatigue resistance, and improve the material's durability. On this basis, polyether polyol and isocyanate prepolymer are added, and the molecular structure of the prepolymer is also richer. The long-chain and star-shaped molecular structures improve the resilience of the polyurethane elastomer; at the same time, the molecular weight and molecular weight distribution width of the prepolymer are increased. The low molecular weight part can play a role similar to plasticizer, making the relative movement between molecular chains easier, and promoting the high molecular weight part to adjust the conformation faster when deformed by force, further improving the resilience of the polyurethane elastomer. However, if the molecular weight distribution width is too large and there are too many low molecular weight components, the overall structure of the elastomer will be loose, the constraints between each other will be worse, and the ability to recover to its original shape after deformation by force will be worse. Therefore, it is necessary to control the input amount of polyether polyol and polyether carbonate polyol and the ratio between the two, control the molecular weight distribution width, and ensure the high resilience of the polyurethane elastomer.

[0006] Furthermore, the polyether carbonate polyol is selected from at least one of PCE-3015E and PCE-2015E, has an average molecular weight of 2000 to 3000, a functionality of 2 to 3, and a CO2 content of 14% to 16%.

[0007] Further, the polyether polyol is selected from at least one of PTMEG2000 and PTMEG3000, with an average molecular weight of 2000 - 3000 and a functionality of 2.

[0008] Further, the isocyanate is at least one of 4,4 - diphenylmethane diisocyanate, 2,4 - diphenylmethane diisocyanate, and carbodiimide - modified isocyanate.

[0009] Further, the polymerization inhibitor is benzoyl chloride or phosphoric acid.

[0010] Another object of the present invention is to provide a method for preparing the above - mentioned modified isocyanate, which includes the following steps:

[0011] By weight, weigh 25 - 30 parts of polyether polyol, 14 - 50 parts of polyether carbonate polyol, 0.003 - 0.01 part of polymerization inhibitor, and 40 - 61 parts of isocyanate;

[0012] Heat the polyether polyol and polyether carbonate polyol for vacuum mixing to dehydrate and cool for later use;

[0013] Add the isocyanate and the polymerization inhibitor into the reaction kettle simultaneously and mix evenly, controlling the temperature of the reaction kettle at 50 - 60 °C; add the polyether polyol and polyether carbonate polyol after the above - mentioned vacuum dehydration treatment into the reaction kettle, control the temperature of the reaction kettle at 88 - 93 °C, and maintain the reaction for 2 - 4 hours; cool down to within 50 °C and discharge to obtain the modified isocyanate.

[0014] Further, the water content of the polyether polyol and polyether carbonate polyol after vacuum dehydration is less than 0.05%, preventing the isocyanate from reacting with water.

[0015] The present invention also provides the application of the above - mentioned modified isocyanate in high - resilience products such as elastic balls, seats, and armrests. The high - resilience polyurethane elastomer improves the user experience, and the durability of the resilience is good.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: 1. The polyether polyol and polyether carbonate polyol are pre - polymerized with the isocyanate. The types of prepolymers are rich, the molecular weight is large, the distribution width of the molecular weight is also large, and the molecular structure of the prepolymer is more abundant, including long - chain and star - shaped molecular structures, greatly improving the resilience of the polyurethane elastomer; 2. The rebound rate of the prepared polyurethane elastomer is as high as over 80%, and the retention rate of the rebound rate is high after heat - aging and ultraviolet tests; 3. The process is simple and easy for industrial production. Specific Embodiments

[0017] The following further illustrates the technical solutions of the present invention in conjunction with embodiments.

[0018] Table 1 is the list of raw materials used in the examples.

[0019] Table 1 List of Raw Materials

[0020]

[0021] The preparation method of the modified isocyanate includes the following steps (see Table 2 for the details of the component shares of each substance in the examples and comparative examples):

[0022] Step 1: Prepare raw materials by weight

[0023] By mass fraction, 25 - 30 parts of polyether polyol, 14 - 50 parts of polyether carbonate polyol, 0.003 - 0.01 part of inhibitor, and 40 - 61 parts of isocyanate;

[0024] Step 2: Synthesis reaction

[0025] (1) Heat the polyether polyol and polyether carbonate polyol for vacuum stirring dehydration, and cool it for use after measuring that the polyether water content is less than 0.05%;

[0026] (2) Add the isocyanate and inhibitor into the reaction kettle simultaneously and mix evenly, and control the temperature of the reaction kettle at 50 - 60 °C; add the polyether polyol and polyether carbonate polyol treated in step (1) into the reaction kettle, control the temperature of the reaction kettle at 88 - 93 °C, and maintain the reaction for 2 - 4 hours; cool down to within 50 °C, and after discharging, obtain Component B: modified isocyanate.

[0027] Table 2 Component of Each Substance in Examples and Comparative Examples

[0028]

[0029] By weight fraction, first heat and stir 80 parts of polyether polyol PTMEG2000 and 20 parts of CHE - 2901L for vacuum dehydration, cool down and then add 0.3 part of water, 0.8 part of catalyst A33 and 0.4 part of foam stabilizer B - 8734, mix evenly and then discharge to form Component A. Mix Component B: modified isocyanate prepared in the examples and comparative examples with Component A according to the ratio in Table 2, inject it into the mold for foaming, the mold temperature is 45 - 50 °C, the curing time is 2 minutes, and then demold to obtain the polyurethane elastomer.

[0030] The prepared polyurethane elastomer is further cured for 48 hours and then subjected to physical property tests, including density, fatigue deformation rate, initial resilience rate, resilience rate after 72 - hour heat aging at 70 °C, and resilience rate after ultraviolet aging test. Among them, the test standard for the resilience rate is based on GB / T6670 - 2008 "Determination of Resilience of Flexible Cellular Plastics by the Ball - Drop Method", and the result data are shown in Table 3.

[0031] Table 3 Test Results of Physical Properties of Examples 1-4 and Comparative Examples 1-5

[0032]

[0033] It can be seen from Table 3 that the polyurethane elastomer materials prepared in Examples 1-4 have a relatively high density, a rebound rate of over 80%, a relatively low fatigue deformation rate, and good retention of the rebound rate of the material after thermal aging and ultraviolet aging, indicating that the prepared polyurethane elastomer has good resilience, and good resistance to fatigue, thermal aging and ultraviolet aging of the resilience.

[0034] Comparing Examples 1-4 with Comparative Example 1-3, the polyurethane elastomers prepared using prepolymerization of polyether polyol and isocyanate alone exhibited lower rebound rates, fatigue deformation rates, and rebound rates against heat aging and UV aging than those of Examples 1-4. Comparing Examples 1-4 with Comparative Examples 4-5, the polyurethane elastomers prepared using prepolymerization of polyether carbonate polyol and isocyanate alone exhibited lower rebound rates, fatigue deformation rates, and rebound rates against heat aging and UV aging than those of Examples 1-4. This is because the prepolymerization of polyether polyol and polyether carbonate polyol with isocyanate produces a richer molecular structure. In particular, the prepolymerization of polyether polyol and isocyanate more easily produces long-chain and star-shaped molecular structures, which enhance the rebound resilience of the polyurethane elastomer. Furthermore, the molecular weight and molecular weight distribution width of the prepolymer are increased. The low molecular weight portion can act like a plasticizer, facilitating relative motion between molecular chains and promoting faster conformational adjustment of the high molecular weight portion when subjected to stress and deformation, further enhancing the rebound resilience of the polyurethane elastomer. However, if the molecular weight distribution width is too large and there are too many low molecular weight components, the overall structure of the elastomer will be loose, the mutual constraints will be poor, and the ability to recover to its original shape after being deformed by force will be poor. Therefore, it is necessary to control the input amount of polyether polyol and polyether carbonate polyol and the ratio between the two. By adjusting the NCO content in the isocyanate prepolymer, the molecular weight distribution width and the mixing ratio of modified isocyanate and isocyanate can be controlled to ensure the high resilience of the polyurethane elastomer. At the same time, ensuring the reaction activity promotes the foaming efficiency and the uniformity of the foam further improves the resilience and resilience durability of the polyurethane elastomer. If the NCO content is too low, it will affect the reaction activity, thereby affecting the curing time of the product, and will also affect the cross-linking density, resulting in a decrease in the mechanical properties of the product, poor elasticity and toughness of the material, and failure to meet the requirements; if the NCO content is too high, the reaction will be difficult to control, resulting in problems such as gelation and sudden polymerization, reducing the flexibility of the product, and cracking and breakage will occur in actual applications. If the NCO content is too high, the storage stability of the modified isocyanate will be poor, the product quality will be reduced, and the manufacturing cost will also be increased. Among them, the NCO content of Example 1 is 14.7%, and the resilience and resilience retention rate are the best. The NCO content of Example 2 is too low, and the NCO content of Example 4 is too high. The density of the polyurethane elastomer is small, the resilience is poor, and the fatigue resistance and aging resistance are also reduced.

[0035] Comparing Example 1 and Example 3, in Example 1, 4,4-diphenylmethane diisocyanate is selected. It has good molecular structure symmetry, high reactivity, high temperature resistance, and good rigidity. Carbodiimide-modified isocyanate has hydrolysis resistance and high stability, with the best resilience, small fatigue deformation rate, and good resilience retention after heat aging and ultraviolet aging. In Example 3, 2,4-diphenylmethane diisocyanate is chosen. Its molecular structure is asymmetric, with low reactivity, but good flexibility. Increasing the variety and molecular weight distribution width of the prepolymer makes different prepolymers bind more closely, increasing the density of the polyurethane. However, the too-wide molecular weight distribution and the closer connection of the prepolymers hinder the stretching of the prepolymer molecular chains, reducing the flexibility of the polyurethane, and thus affecting the resilience of the polyurethane. Therefore, it is not the case that the more the variety and molecular weight distribution width of the prepolymer are, the better. Reasonably controlling the molecular weight and structural type of the prepolymer can make the polyurethane obtain better resilience on the premise of meeting the density requirements; in addition, reasonably controlling the molecular weight and structural type of the prepolymer also promotes the stability of the binding between molecular chains, improving the anti-fatigue, heat aging resistance, and ultraviolet aging resistance of the polyurethane.

Claims

1. A modified isocyanate, characterized in that, By weight parts, it contains 25 - 30 parts of polyether polyol, 14 - 50 parts of polyether carbonate polyol, 0.003 - 0.01 part of polymerization inhibitor, and 40 - 61 parts of isocyanate; the modified isocyanate is a mixture of an NCO group-terminated modified isocyanate prepolymer prepared by reacting polyether polyol and polyether carbonate polyol with isocyanate and isocyanate.

2. The modified isocyanate according to claim 1, characterized in that, The NCO content of the modified isocyanate prepolymer is 10 - 18%.

3. The modified isocyanate according to claim 2, wherein The modified isocyanate prepolymer contains an NCO group-terminated modified isocyanate prepolymer prepared by reacting polyether polyol with isocyanate, an NCO group-terminated modified isocyanate prepolymer prepared by reacting polyether carbonate polyol with isocyanate, and an NCO group-terminated modified isocyanate prepolymer prepared by reacting polyether polyol and polyether carbonate polyol together with isocyanate.

4. The modified isocyanate according to claim 1, characterized in that The polyether carbonate polyol is selected from at least one of PCE-3015E and PCE-2015E, with an average molecular weight of 2000 - 3000, a functionality of 2 - 3, and a CO2 content of 14% - 16%.

5. The modified isocyanate according to claim 1, characterized in that, The polyether polyol is selected from at least one of PTMEG2000 and PTMEG3000, with an average molecular weight of 2000 - 3000 and a functionality of 2.

6. The modified isocyanate according to claim 1, wherein The isocyanate is at least one of 4,4-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, and carbodiimide-modified isocyanate.

7. The modified isocyanate according to claim 1, wherein The polymerization inhibitor is benzoyl chloride or phosphoric acid.

8. A method for preparing the modified isocyanate according to any one of claims 1 to 7, characterized in that, It includes the following steps: By weight parts, weigh 25 - 30 parts of polyether polyol, 14 - 50 parts of polyether carbonate polyol, 0.003 - 0.01 part of polymerization inhibitor, and 40 - 61 parts of isocyanate; Heat the polyether polyol and polyether carbonate polyol for vacuum dehydration, and cool for later use; Add the isocyanate and the polymerization inhibitor into the reaction kettle simultaneously and mix evenly, control the temperature of the reaction kettle at 50 - 60 °C; add the polyether polyol and polyether carbonate polyol after the above vacuum dehydration treatment into the reaction kettle, control the temperature of the reaction kettle at 88 - 93 °C, and maintain the reaction for 2 - 4 hours; cool down to obtain the modified isocyanate.

9. The method for preparing the modified isocyanate according to claim 8, characterized in that, After vacuum dehydration, the water content of the polyether polyol and polyether carbonate polyol is less than 0.05%.

10. Application of the modified isocyanate according to any one of claims 1 - 9 in high resilience products.

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