A modified isocyanate, its preparation method and application

Abstract

The present invention belongs to the technical field of the preparation of modified isocyanates, and particularly relates to a modified isocyanate, a preparation method thereof and an application; the modified isocyanate comprises: 70-94 parts of an organic isocyanate; 6-30 parts of polyether polyol i; the polyether polyol i is a polyether polyol randomly copolymerized with EO / PO monomers and capped with EO, or a polyether polyol block copolymerized with PO monomers and capped with EO, or a mixture of the two; the average molecular weight of the polyether polyol i is 2000-10000, the functionality is 2-4, the EO content is 5-29 wt%, the hydroxyl value is 20-80 mgKOH / g, and the primary hydroxyl group content is greater than or equal to 70%. The modified isocyanate of the present invention has good storage stability, and the slow-rebound polyurethane foam prepared therefrom has fine open cells, and has the advantages of high tolerance, good tear performance, and good sound absorption and sound insulation effects.

Description

Technical Field

[0001] The present invention belongs to the technical field of modified isocyanate preparation, and particularly relates to a modified isocyanate, a preparation method thereof, and an application thereof. Background Art

[0002] As a main raw material in the polyurethane field, organic isocyanate has a large number of applications in industries such as polyurethane foam, elastomer, and adhesive; among them, MDI and its prepolymer have extensive applications in automotive interior products; viscoelastic foam can reduce the vibration generated during vehicle driving and improve the comfort inside the vehicle due to its excellent damping performance. At the same time, in terms of sound absorption and insulation, compared with high resilience foam, slow rebound foam contains segments with a high EO content, and the cell walls are softer, so the cell walls have better absorption of sound waves. Therefore, viscoelastic foam will receive more and more attention in automotive acoustic products; however, traditional slow rebound foam has problems such as closed cell shrinkage, poor tear performance, and its fluidity cannot meet the production and performance requirements of automotive acoustic products.

[0003] In view of the defects such as closed cell shrinkage of traditional slow rebound foam products, the solutions of the prior art mainly include the following three aspects:

[0004] (1) By selecting the type of silicone oil in the combined polyether (combined A material), controlling the surface tension during cell formation in the foaming reaction, and adjusting the open / closed cell property of the cells; (2) By designing the catalyst system in the combined polyether, adjusting the competitive reaction rate of water, polyether polyol and isocyanate in the combined polyether, so as to control the cell structure and achieve an open cell state; (3) By selecting the chain segment structure composition of the combined polyether polyol (combined A material) and the functionality and structure of the isocyanate in the isocyanate component (combined B material), an open cell system is designed.

[0005] Chinese patent document CN 109021193 A discloses a highly breathable polyurethane foam prepared from MDI as a raw material, which does not contain TDI component, is safe and environmentally friendly. Although the prepared polyurethane foam has good open cell breathability, water permeability and appropriate viscoelasticity, the tear strength of the foam is low (less than 2 N / cm), which does not meet the foam physical property requirements of the automotive industry.

[0006] Chinese patent document CN 116239746 A discloses a viscoelastic polyurethane foam and its preparation method and uses, mainly solving the problems of poor medium and low frequency sound absorption performance and hardening at low temperature of polyurethane foam in the prior art; the isocyanate group content in component B is 26-31%, and by weight, it includes 60-90 parts of modified MDI and 10-40 parts of polymeric MDI; the EO content of polyether polyol A1 is 50-100%, and the functionality is 3-6; the EO content of polyether polyol A2 is 15-30%, and the functionality is 3-6. However, the compression set of the obtained foam is poor, its application on automotive acoustic carpets has limitations, and at the same time, the flow filling property is poor, and the density of the actually produced products is high, which cannot well meet the current development trend of automotive lightweighting.

[0007] Then, how to prepare an open-cell, slow-rebound black material (isocyanate component) from the third aspect, and then select the appropriate type and dosage of silicone oil to design an open-cell slow-rebound system, so that the formulation tolerance is high, the foaming ratio of the foam, the foam appearance and performance indicators meet the actual needs of customers, is a direction worthy of further research. Summary of the Invention

[0008] The purpose of the present invention is to provide a modified isocyanate, its preparation method and application in view of the problems of poor appearance of foam products prepared from existing modified MDI prepolymers, high closed-cell rate, insufficient flow filling property and poor physical properties; this modified isocyanate has good storage stability, and the slow-rebound polyurethane foam prepared by it has delicate open cells, and has the advantages of high tolerance, good tear performance and good sound absorption and insulation effects.

[0009] To achieve the above purpose, the present invention provides the following technical solutions:

[0010] In the first aspect, a modified isocyanate is provided. By mass, its raw material components include: organic isocyanate, 70-94 parts (for example, 72 parts, 74 parts, 75 parts, 80 parts, 85 parts, 90 parts, 92 parts); polyether polyol i, 6-30 parts (for example, 7 parts, 8 parts, 10 parts, 12 parts, 15 parts, 20 parts, 24 parts, 25 parts, 28 parts);

[0011] Among them,

[0012] The polyether polyol i is a polyether polyol copolymerized with EO / PO monomers in a random manner and capped with EO, or a polyether polyol copolymerized with PO monomers in a block manner and capped with EO, or a mixture of the two;

[0013] The average molecular weight of the polyether polyol i is 2000 to 10000 (for example, 2500, 3000, 4000, 4500, 5000, 5500, 6000, 7000, 8000, 8500, 9000, 9500), the functionality is 2 to 4 (for example, 2.5, 3, 3.5), the mass percentage content of EO is 5 to 29 wt% (for example, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 28 wt%), the mass percentage content of PO is 71 to 95 wt% (for example, 72 wt%, 74 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 92 wt%, 94 wt%), the hydroxyl value is 20 - 80 mgKOH / g (for example, 22 mgKOH / g, 25 mgKOH / g, 30 mgKOH / g, 35 mgKOH / g, 40 mgKOH / g, 50 mgKOH / g, 55 mgKOH / g, 60 mgKOH / g, 70 mgKOH / g, 75 mgKOH / g), and the primary hydroxyl group content is greater than or equal to 70% (for example, 72%, 74%, 75%, 76%, 80%, 82%, 85%, 90%, 92%, 94%, 95%, 96%).

[0014] According to the modified isocyanate provided by the present invention, in some embodiments, in the polyether polyol i, the initiator used is a small molecule polyol, and for example, it can be selected from one or more of glycerol, trimethylolpropane or pentaerythritol.

[0015] According to the modified isocyanate provided by the present invention, in some embodiments, the mass percentage content of isocyanate groups in the modified isocyanate is 22 to 32 wt%, for example, 24 wt%, 25 wt%, 26 wt%, 28 wt%, 30 wt%, 31 wt%.

[0016] In some embodiments, the functionality of the modified isocyanate is 2.2 - 2.8, for example, 2.4, 2.5, 2.6, 2.7.

[0017] According to the modified isocyanate provided by the present invention, in some embodiments, by mass parts, the organic isocyanate includes the following components in the following weight parts:

[0018] 2,4-diphenylmethane diisocyanate, 0 to 20 parts (for example, 1 part, 2 parts, 4 parts, 5 parts, 8 parts, 10 parts, 14 parts, 16 parts, 18 parts);

[0019] 4,4'-diphenylmethane diisocyanate, 35 to 65 parts (for example, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts); and

[0020] Polymethylene polyphenyl isocyanate, 30 to 55 parts (for example, 35 parts, 40 parts, 45 parts, 50 parts).

[0021] According to the modified isocyanate provided by the present invention, in some embodiments, based on the total mass of the organic isocyanate and polyether polyol i, the modified isocyanate further includes an antioxidant, and its content is 0 to 800 ppm (for example, 1 ppm, 10 ppm, 20 ppm, 40 ppm, 60 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm, 550 ppm, 600 ppm, 750 ppm), preferably 50 to 500 ppm.

[0022] In a second aspect, a method for preparing the modified isocyanate as described above is provided, including the following steps:

[0023] (1) Under the protection of an inert gas (such as nitrogen), the organic isocyanate, polyether polyol i, and optionally an antioxidant are mixed, and then a urethane modification reaction is carried out at 55 to 90 °C (such as 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C) to obtain a reaction material;

[0024] (2) Sampling and testing the reaction material as described above. When the mass percentage content of isocyanate groups reaches 22 to 32%, the reaction is stopped; then the temperature of the system (the reaction material) is lowered to 40 to 70 °C (for example, 50 °C, 60 °C, 65 °C), and stirred for 2 to 4 hours (such as 2.5 hours, 3 hours, 3.5 hours) to end the reaction and obtain the modified isocyanate.

[0025] In a third aspect, an application of the modified isocyanate as described above or the modified isocyanate prepared by the preparation method as described above in automotive slow rebound foam products is provided.

[0026] According to the application provided by the present invention, in some embodiments, the slow rebound foam is obtained by mixing and reacting component A and component B; wherein,

[0027] Component A is an isocyanate-reactive component, and component B is the modified isocyanate as described above;

[0028] The isocyanate index is 50 - 90% (that is, the molar amount of isocyanate groups NCO in component B to the molar amount of hydroxyl groups OH in component A), for example, 55%, 60%, 70%, 80%.

[0029] According to the application provided by the present invention, in some embodiments, the isocyanate-reactive component (component A) includes polyether polyol ii, a catalyst, a surfactant, and a blowing agent; wherein,

[0030] The polyether polyol ii is selected from one or more of the soft foam polyols, with an average functionality of 2 to 4 and a hydroxyl value of 20 to 150 mg KOH / g (for example, 25 mg KOH / g, 40 mg KOH / g, 50 mg KOH / g, 60 mg KOH / g, 80 mg KOH / g, 100 mg KOH / g, 120 mg KOH / g, 130 mg KOH / g, 145 mg KOH / g), and the ethylene oxide content is 30 to 90% (for example, 35%, 40%, 50%, 60%, 80%, 85%);

[0031] The catalyst is selected from one or more of bis(2-dimethylaminoethyl) ether, N,N,N'-trimethyl-N'-hydroxyethyl bisaminoethyl ether, N,N-dimethyl-N',N'-bis(2-hydroxypropyl)-1,3-propanediamine, dimethylaminopropylamine, N,N'-dimethylethanolamine, bis(3-dimethylaminopropyl)aminopropanol, tetramethyldipropylenetriamine, pentamethyldiethylenetriamine, triethylenediamine, dimethylaminopropylamine, N,N,N'-trimethyl-N'-hydroxyethyl bisaminoethyl ether, bis(3-dimethylaminopropyl)aminopropanol, tetramethyldipropylenetriamine, and 3,3'-iminobis(N,N-dimethylpropylamine);

[0032] The surfactant is selected from polyorganosiloxane-polyalkylene oxide block copolymers;

[0033] The blowing agent is selected from one or more of water, CO2, dichlorofluoroethane, butane, n-pentane, cyclopentane, and isopentane, and preferably water.

[0034] In some embodiments of the application provided by the present invention, in the isocyanate-reactive component (Component A), based on 100 parts by weight of the polyether polyol ii, the weight parts of each raw material are as follows:

[0035] Catalyst, 0.5 - 2.5 parts (for example, 0.6 parts, 0.8 parts, 1.0 parts, 1.5 parts, 2.0 parts);

[0036] Surfactant, 0.2 - 2.0 parts (for example, 0.4 parts, 0.5 parts, 0.8 parts, 1.0 parts, 1.5 parts, 1.8 parts);

[0037] Blowing agent, 1.5 - 6.0 parts (for example, 1.8 parts, 2.0 parts, 2.5 parts, 3.0 parts, 4.0 parts, 5.0 parts, 5.5 parts).

[0038] In the present invention, the specific steps of the application can be:

[0039] Prepare Component A according to the formula of each component, then pour the modified isocyanate as Component B into the prepared Component A, stir at 2000 - 3000 r / min for 5 - 8 s, and then pour the obtained liquid material into a foaming mold for foaming and sample preparation. Among them, the mold temperature can be 60 - 65 °C, the demolding time can be 1 - 2 min, and the overall molding density can be 40 - 80 kg / m 3 , and then cure for 24 - 48 h to obtain a slow - rebound polyurethane foam.

[0040] In the fourth aspect, there is provided an automotive slow - rebound foam prepared by the application as described above. For example, the loss factor of the automotive slow - rebound foam is equal to or greater than 0.3, the compression set (90%) is less than or equal to 10%, and the tear strength is equal to or greater than 2 N / cm.

[0041] For polyether polyols, due to the structural differences between EO and PO, the polarities of the EO polyether segments and PO polyether segments obtained by polymerization are different, and they are actually incompatible; polyurethane products are divided into soft segments and hard segments. The hard segments are urethanes with relatively large polarities, and the soft segments are polyether segments. Among them, the EO polyether segment has a larger polarity than the PO polyether segment, the oxygen atom is exposed, and its lone pair of electrons can form hydrogen bonds with the hydrogen atoms of the hard - segment urethane, enabling the soft - segment polyether and the hard - segment urethane to form a micro - phase mixing, thereby increasing the glass transition temperature of the soft segment. However, due to the steric hindrance of the methyl group in the PO polyether segment, the polarity difference between the soft - segment polyether and the hard - segment urethane is relatively large, making it difficult to form a micro - phase mixing, and the phase separation is very good; therefore, controlling the EO content of the polyether polyol in the modified B component (modified isocyanate component) within a suitable range can affect the phase - separation degree of the hard and soft segments of the polyurethane foam, thereby affecting the open - cell and closed - cell degrees of the foam. On the contrary, the slow - rebound composite A component (mainly containing polyether polyol component) is a polyether system with a high EO content.

[0042] In the modified isocyanate of the present invention, the polyether polyol used is a selected polyether with a high PO content, which can affect the phase separation of the slow rebound composite A component polyol and the hard segment urethane used in the preparation of polyurethane foam. On this basis, through the optimization of the EO content in the polyether polyol used in the modified isocyanate, the inventor found that using a polyether polyol with a total EO content not exceeding 30 wt% in the modified isocyanate component can achieve the effect of cell opening in the slow rebound system, and as the PO chain segment increases, the cell opening effect becomes more obvious. However, when a polyether polyol with a total EO content not exceeding 30 wt% used in the modified isocyanate component is added to the composite A component of the slow rebound polyurethane foam, there will be a defect of stratification due to poor compatibility. Therefore, the present invention mainly modifies the polyether polyol with a specific polyether structure and EO content by pre-polymerizing with isocyanate, and regulates the phase separation degree of the hard and soft segments through the arrangement and proportion of the specific polyether EO chain segment and PO chain segment to achieve the cell opening state of the polyurethane foam.

[0043] The beneficial effects of the technical solution of the present invention are at least as follows:

[0044] During the process of making automotive viscoelastic foam, at the same isocyanate index and with the same slow rebound composite polyether (component A in polyurethane foam), compared with the blended isocyanate composition without modification by polyether polyol, the foam prepared from the modified isocyanate of the present invention has more open cells, finer surface pores, and a good feel; compared with the modified MDI system with a high 2,4'-MDI content, since the content of 2,4'-MDI in the modified isocyanate of the present invention is lower, the foam prepared also has more open cells and has good performance in terms of physical properties (such as compression set that automotive carpet products are more concerned about); in terms of fluidity, the foam prepared using the modified isocyanate of the present invention has better filling properties and can achieve the preparation of low-density products; in terms of storage stability, the modified isocyanate of the present invention remains clear, transparent, and without crystallization after being stored at 0 °C for 3 months. Description of the Drawings

[0045] Figure 1 Shows the shrinkage states of the foam at different molding densities, from left to right are the non-shrinkage state, slight shrinkage state, and severe shrinkage state. Detailed Description of the Invention

[0046] In order to be able to understand the technical features and content of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the examples, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Those not specified in the examples are carried out under conventional conditions or conditions recommended by the manufacturer.

[0047] Test Method:

[0048] (1) The method for evaluating the storage stability of the modified isocyanate in the present invention is as follows:

[0049] Seal the modified isocyanate sample in a 500 mL iron bottle and store it at 0 °C for 3 months, and observe its crystallization state, whether the drum bulges, etc.

[0050] (2) The method for testing the performance of the molded slow-rebound foamed product in the present invention is as follows:

[0051] Tensile strength (kPa): GB / T 6344-2008;

[0052] Elongation at break (%): GB / T 6344-2008;

[0053] Tear strength (N / cm): GB / T 10808-2006;

[0054] Compression set (%): GB / T 6669-2008;

[0055] Compression hardness (KPa): GB / T 29901-2013;

[0056] Loss factor: Use a dynamic method loss factor tester and test according to the Z-Nr 1933 613.3 standard;

[0057] Sound absorption coefficient: GB / T 18696.1-2004, the test range of the equipment is 100~10000 Hz; Cut the test specimens to be tested into circular specimens with diameters of 9.6 cm and 3 cm respectively. The 9.6 cm specimen is used to test the low-frequency sound absorption coefficient, and the 3 cm specimen is used to test the high-frequency sound absorption coefficient. Measure the sound absorption coefficients at 500 Hz, 630 Hz, 800 Hz, 1000 Hz, 1250 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, 4000 Hz, 5000 Hz, 6300 Hz, and 10000 Hz respectively.

[0058] Table 1 Organic isocyanate raw materials used in the modified isocyanate and their sources

[0059]

[0060] Table 2 Polyether polyol raw materials used in the modified isocyanate and their sources

[0061]

[0062] Table 3 Raw materials of component A in the slow-rebound foam and their sources

[0063]

[0064]

Example 1

[0065] The preparation method of the modified isocyanate comprises the following steps:

[0066] (1) Under the protection of nitrogen, 626 g of WANNATE MDI-100, 210 g of WANNATE MDI-50, and 906 g of WANNATE PM-200 are added to a 5-L glass reaction kettle, heated to 75°C, and stirred until completely melted; then the reaction kettle is heated to 80°C, 258 g of polyether polyol A is added, and the mixture is stirred and reacted for 2 hours to obtain a reaction material;

[0067] (2) The reaction material is sampled and tested. When the mass percentage content of isocyanate groups reaches 22-32%, the reaction is stopped; then the reaction material obtained in the reaction kettle is cooled to 60°C and stirred for 2 hours to end the reaction, and a modified isocyanate is obtained.

[0068] The performance of the prepared modified isocyanate is evaluated, and the results are shown in Table 4.

[0069] Preparation of slow rebound polyurethane foam:

[0070] Component A is prepared according to the raw material formula shown in Table 6, and then the modified isocyanate prepared above is used as Component B and poured into the prepared Component A according to the dosage ratio shown in Table 6. The mixture is stirred at 3000 r / min for 5-8 s, and then the obtained liquid material is poured into a foaming mold for foaming and sample preparation. Among them, the mold temperature is 65°C, the demolding time is 2 min, and the overall molding density is 65 kg / m 3 , after the prepared polyurethane foam is cured for 48 hours, performance testing is carried out, and the physical property test results are shown in Table 7.

[0071]

Examples 2-7

[0072] In Examples 2-7, the preparation method of the modified isocyanate refers to Example 1, the difference is that: the types and ratios of the reaction raw materials of the modified isocyanate are different, and the specific details are shown in Table 4; a modified isocyanate is obtained.

[0073] The performance of the prepared modified isocyanate is evaluated, and the results are shown in Table 4.

[0074] Preparation of slow rebound polyurethane foam:

[0075] Prepare Component A according to the raw material formula shown in Table 6, and then pour the modified isocyanate prepared as above as Component B into the prepared Component A according to the dosage ratio shown in Table 6, stir for 5 - 8 s under the condition of 3000 r / min, and then pour the obtained liquid material into a foaming mold for foaming sample preparation. Among them, the mold temperature is 65 °C, the demolding time is 2 min, and the overall molding density is 65 kg / m 3 , after the prepared polyurethane foam is cured for 48 hours, perform performance testing, and the physical property test results are shown in Table 7.

[0076] Table 4 Components, Dosages and Stability Test Results of Modified Isocyanate

[0077]

[0078]

Comparative Example 1

[0079] In this Comparative Example 1, the modified isocyanate used is commercially available WANNATE 8223B, where WANNATE 8223B is an isocyanate composition without polyether polyol, and its main components are a mixture of 2,4-MDI, 4,4’-MDI and polymethylene polyphenyl isocyanate.

[0080] Perform performance evaluation on this modified isocyanate, and the results are shown in Table 5.

[0081] Preparation of slow rebound polyurethane foam:

[0082] Prepare Component A according to the raw material formula shown in Table 6, and then pour the modified isocyanate as above as Component B into the prepared Component A according to the dosage ratio shown in Table 6, stir for 5 - 8 s under the condition of 3000 r / min, and then pour the obtained liquid material into a foaming mold for foaming sample preparation. Among them, the mold temperature is 65 °C, the demolding time is 2 min, and the overall molding density is 65 kg / m 3 , after the prepared polyurethane foam is cured for 48 hours, perform performance testing, and the physical property test results are shown in Table 7.

[0083]

Comparative Example 2

[0084] In this Comparative Example 2, the modified isocyanate used is commercially available WANNATE 80339, where the main component of WANNATE 80339 is the product after modifying a mixture of 2,4-MDI, 4,4’-MDI and polymethylene polyphenyl isocyanate with polyether polyol. Among them, the polyether polyol is a polyether polyol with a high EO content, and the EO content is greater than 70 wt%.

[0085] Perform performance evaluation on this modified isocyanate, and the results are shown in Table 5.

[0086] Preparation of slow rebound polyurethane foam:

[0087] Prepare component A according to the raw material formula shown in Table 6, and then pour the modified isocyanate as component B into the prepared component A according to the dosage ratio shown in Table 6, stir at 3000 r / min for 5 - 8 s, and then pour the obtained liquid material into a foaming mold for foaming and sample preparation. Among them, the mold temperature is 65 °C, the demolding time is 2 min, and the overall molding density is 65 kg / m 3 . After the prepared polyurethane foam is cured for 48 hours, performance testing is carried out, and the physical property test results are shown in Table 7.

[0088]

Comparative Example 3

[0089] The preparation method of the modified isocyanate in this Comparative Example 3 refers to Example 1, the difference is that: the reaction raw materials of the modified isocyanate (the polyether polyol used is a short-chain polyether polyol), parameters such as the raw material ratio are different, as specifically shown in Table 5; the modified isocyanate is obtained.

[0090] Perform performance evaluation on the prepared modified isocyanate, and the results are shown in Table 5.

[0091] Preparation of slow rebound polyurethane foam:

[0092] Prepare component A according to the raw material formula shown in Table 6, and then pour the modified isocyanate prepared above as component B into the prepared component A according to the dosage ratio shown in Table 6, stir at 3000 r / min for 5 - 8 s, and then pour the obtained liquid material into a foaming mold for foaming and sample preparation. Among them, the mold temperature is 65 °C, the demolding time is 2 min, and the overall molding density is 65 kg / m 3 . After the prepared polyurethane foam is cured for 48 hours, performance testing is carried out, and the physical property test results are shown in Table 7.

[0093]

Comparative Example 4

[0094] The preparation method of the modified isocyanate in this Comparative Example 4 refers to Example 1, the difference is that: the reaction raw materials of the modified isocyanate (the polyether polyol used is a pure EO polyether polyol), parameters such as the raw material ratio are different, as specifically shown in Table 5; the modified isocyanate is obtained.

[0095] Perform performance evaluation on the prepared modified isocyanate, and the results are shown in Table 5.

[0096] Preparation of slow rebound polyurethane foam:

[0097] Prepare Component A according to the raw material formula shown in Table 6, and then pour the modified isocyanate prepared as above as Component B into the prepared Component A according to the dosage ratio shown in Table 6, stir at 3000 r / min for 5 - 8 s, and then pour the obtained liquid material into a foaming mold for foaming and sample preparation. Among them, the mold temperature is 65 °C, the demolding time is 2 min, and the overall molding density is 65 kg / m 3 . After the prepared polyurethane foam is cured for 48 hours, perform performance testing, and the physical property test results are shown in Table 7.

[0098] Table 5 Components, Their Dosages and Stability Test Results in Modified Polyisocyanate

[0099]

[0100] Table 6 Raw Material Formula of Slow Rebound Polyurethane Foam

[0101]

[0102] Note: The modified isocyanate in Table 6 refers to the modified isocyanate prepared or provided in each example and comparative example.

[0103] Table 7 Performance Test Results of Slow Rebound Polyurethane Foams in Examples 1 - 7 and Comparative Examples 1 - 4

[0104]

[0105] Judging from the physical property results, under the condition of the same isocyanate index, the polyurethane foam prepared with the modified isocyanate obtained through each example has a lower free foam density. Its tensile strength does not increase significantly as a whole, but the elongation at break and tear strength are significantly improved. In automotive soft foam products, the general requirement for the tear performance of PU materials is above 2.0 N / cm. The Component B (modified isocyanate) of the present invention can greatly improve the problem of poor tear performance of slow rebound soft foam products. At the same time, due to the selection of polyether polyol in Component B (modified isocyanate), the open cell rate of the polyurethane foam system is very high, and the compression set of the foam is greatly improved. Especially in automotive carpet products, this polyurethane foam product can remain unchanged after long-term use.

[0106] In Comparative Example 1, the isocyanate component was an isocyanate composition without polyether polyol. The free foam density of the prepared polyurethane foam was relatively high, the elongation at break and tear strength were significantly poor, and the compression set of the foam was also not good. In Comparative Example 2, the isocyanate component was a product obtained by modifying an isocyanate mixture with a polyether polyol with a high EO content. The elongation at break and tear strength of the prepared polyurethane foam were significantly poor, and the compression set of the foam was also not good. In Comparative Example 3, the isocyanate component was a product obtained by modifying an isocyanate mixture with a pure PO polyether polyol. The free foam density of the prepared polyurethane foam was relatively high, the elongation at break and tear strength were significantly poor, and the compression set of the foam was also not good. In Comparative Example 4, the isocyanate component was a product obtained by modifying an isocyanate mixture with a pure EO polyether polyol. The storage stability of this modified isocyanate was very poor. The free foam density of the prepared polyurethane foam was relatively high, the elongation at break and tear strength were significantly poor, and the compression set of the foam was also not good.

[0107] Table 8 Comparison of the open-cell and closed-cell properties of polyurethane foams at different isocyanate indices

[0108]

[0109] As shown in Table 8, for the polyurethane foams prepared with the modified isocyanates obtained in Examples 1, 5, and 7 at different isocyanate indices, the foams did not show shrinkage. This indicates that the polyurethane foams prepared with the modified isocyanates obtained by the present invention have a very high index tolerance in terms of foam open-cell formation. When the isocyanate index is between 55 and 75, the open-cell rate of the obtained molded foams is very high, the foam appearance is full and well-defined, and the pressing and rebound effect is very good. However, for the polyurethane foams prepared with the modified isocyanates of Comparative Examples 1 - 3 at different isocyanate indices, when the isocyanate index is between 60 and 75, the foams will all show shrinkage, and with the increase of the isocyanate index, the shrinkage degree becomes more and more serious. This shows that the open-cell rate of the polyurethane foams prepared with commercially available WANNATE 8223B and WANNATE 80339 is very low, and with the increase of the index, the closed-cell rate of the foam increases, resulting in different degrees of shrinkage of the molded foam and wrinkles on the surface, and mechanical defoaming is required to open the pores.

[0110] In addition, the comparison of the open-cell and closed-cell properties of the prepared foams with the increase of the molded density was further studied, as shown in Table 9.

[0111] Table 9 Comparison of the open-cell and closed-cell properties of the obtained polyurethane foams at different molded densities

[0112]

[0113] As shown in Table 9, for the polyurethane foams prepared with the modified isocyanates obtained in Examples 1, 5, and 7 at different molding densities, no shrinkage phenomenon occurred in the foams, indicating that the polyurethane foams prepared with the modified isocyanates obtained by the present invention have a very high molding density tolerance in terms of foam cell opening. When the molding density is between 40 - 80 kg / m 3 The obtained molded foam has a very high cell opening rate, the foam appearance is full and the edges are distinct, and the pressing and rebound effect is very good. However, for the polyurethane foams prepared with the modified isocyanates of Comparative Examples 1 - 3 at different molding densities, when the molding density is between 50 - 80 kg / m 3 Shrinkage phenomenon occurred in the foams, and with the increase of the molding density, the degree of shrinkage became more and more serious, indicating that the cell opening rates of the polyurethane foams prepared with commercially available WANNATE8223B and WANNATE 80339 are very low, and with the increase of the molding density, the closed cell rate of the foam increases, resulting in different degrees of shrinkage of the molded foam and wrinkles on the surface.

[0114] Among them, for the non - shrinkage state, slight shrinkage state, and severe shrinkage state, please refer to the Figure 1 illustrations shown.

[0115] Flowability investigation: The flow and filling properties of the materials during the preparation of polyurethane foams in a mold with a certain shape were respectively studied for comparison.

[0116] Table 10 Comparison of flow and filling properties

[0117]

[0118] The flow and filling properties of the materials during the preparation of polyurethane foams using the modified isocyanates of Example 1, Example 5, and Example 7 and Comparative Examples 1 - 2 and Comparative Example 4 as raw materials in a mold with a certain shape were respectively compared. The volume of the mold used is 1.3 L, and the minimum foam mass required to fill the mold is the limit filling weight. From the comparison results shown in Table 10, due to the relatively low functionality of the modified isocyanates of the present invention, the modified polyether polyol chain segments have a small polarity and low viscosity, which makes their fluidity good. Eventually, the materials have good filling properties in the mold, require less foam mass to fill the same - volume mold, and have a lower foam density, better meeting the current development trend of automotive lightweight and low - cost.

[0119] Sound absorption effect study:

[0120] The sound absorption effects of the polyurethane foams prepared with the modified isocyanates of each example and comparative example were studied. The polyurethane foams prepared with the modified isocyanates of the present invention have many open cells and the obtained foam cells are delicate, so their sound absorption effects have obvious advantages. The test data of the sound absorption results are shown in Table 11.

[0121] Table 11 Test data of sound absorption effect of polyurethane foam

[0122]

[0123] By using the modified isocyanate of the present invention, due to the high open-cell rate of the foam in the formulation system, sound waves can enter the cells, and sound wave refraction occurs in the cells. In addition, the soft cell walls generated by the polyether with a high EO content in Component A convert the vibration energy of the sound waves entering the cell walls into heat energy and absorb it by the cell walls. Therefore, the sound absorption effect is excellent, and the sound absorption coefficient of the foam prepared by the modified isocyanate currently on the market is higher in both low-frequency and medium-high frequency ranges.

[0124] It can be seen that the viscoelastic polyurethane foam prepared by the modified isocyanate of the present invention has excellent sound absorption performance, damping performance, tear performance, and good compression set while having good index tolerance, density tolerance, and flow filling properties, and can be used in the industrial applications of sound absorption carpets, front panels, and acoustic packages for automotive interior parts.

[0125] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those of ordinary skill in the art without departing from the gist of the present invention.

Claims

1. A modified isocyanate, characterized in that, On a mass parts basis, its raw material components include: organic isocyanate, 70 - 94 parts; polyether polyol i, 6 - 30 parts; Among them, the polyether polyol i is a polyether polyol randomly copolymerized with EO / PO monomers and capped with EO, or a polyether polyol block copolymerized with PO monomers and capped with EO, or a mixture of the two; the average molecular weight of the polyether polyol i is 2000 - 10000, the functionality is 2 - 4, the mass percentage content of EO is 5 - 20 wt%, the mass percentage content of PO is 80 - 95 wt%, the hydroxyl value is 20 - 80 mgKOH / g, and the primary hydroxyl group content is greater than or equal to 70%.

2. The modified isocyanate according to claim 1, wherein The isocyanate group mass percentage content of the modified isocyanate is 22 - 32 wt%.

3. The modified isocyanate according to claim 1, wherein The functionality of the modified isocyanate is 2.2 - 2.

8.

4. The modified isocyanate according to claim 1, characterized in that, On a mass parts basis, the organic isocyanate includes the following components in the following weight parts: 2,4-diphenylmethane diisocyanate, 0 - 20 parts; 4,4'-diphenylmethane diisocyanate, 35 - 65 parts; and polymethylene polyphenyl isocyanate, 30 - 55 parts.

5. The modified isocyanate according to claim 1, wherein, Based on the total mass parts of the organic isocyanate and the polyether polyol i, the modified isocyanate further includes an antioxidant, and its content is 0 - 800 ppm.

6. The preparation method of the modified isocyanate according to any one of claims 1-5, characterized in that, It includes the following steps: (1) Under the protection of an inert gas, mix the organic isocyanate, the polyether polyol i, and optionally the antioxidant, and then carry out a urethane modification reaction at 55 - 90 °C to obtain a reaction material; (2) Sample and test the above-mentioned reaction material. When the isocyanate group mass percentage content reaches 22 - 32%, stop the reaction; then lower the temperature of the system to 40 - 70 °C and stir for 2 - 4 hours to end the reaction and obtain the modified isocyanate.

7. Application of the modified isocyanate according to any one of claims 1 - 5 or the modified isocyanate prepared by the preparation method according to claim 6 in automotive slow rebound foam products.

8. The application according to claim 7, characterized in that, By mixing component A and component B for reaction, the slow rebound foam is obtained; among them, component A is an isocyanate-reactive component, and component B is the above-mentioned modified isocyanate; The isocyanate index is 50 - 90%.

9. The application according to claim 8, wherein The isocyanate-reactive component includes polyether polyol ii, a catalyst, a surfactant, and a blowing agent; among them, the polyether polyol ii is selected from one or more of soft foam polyols, its average functionality is 2 - 4, the hydroxyl value is 20 - 150 mgKOH / g, and the ethylene oxide content is 30 - 90%; the catalyst is selected from one or more of bis(2-dimethylaminoethyl) ether, N,N,N'-trimethyl-N'-hydroxyethyl bisaminoethyl ether, N,N-dimethyl-N',N'-bis(2-hydroxypropyl)-1,3-propanediamine, dimethylaminopropylamine, N,N'-dimethylethanolamine, bis(3-dimethylaminopropyl) aminoisopropanol, tetramethyldipropylenetriamine, pentamethyldiethylenetriamine, and triethylenediamine; the surfactant is selected from polyorganosiloxane-polyalkylene oxide block copolymers; The foaming agent is selected from one or more of water, CO2, dichlorofluoroethane, butane, n-pentane, cyclopentane, and isopentane.

10. The slow rebound foam for automobiles prepared by the application according to any one of claims 7-9.

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