Modified isocyanate as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of preparation of modified isocyanate, and particularly relates to modified isocyanate as well as a preparation method and application thereof. The modified isocyanate comprises the following components in parts by weight: 70-94 parts of organic isocyanate; 6 to 30 parts of polyether polyol i; the polyether polyol i is EO / PO monomer random copolymerized and EO-terminated polyether polyol, or PO monomer block copolymerized and EO-terminated polyether polyol, or a mixture of the EO monomer random copolymerized and EO-terminated polyether polyol and the PO monomer block copolymerized and EO-terminated polyether polyol; 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 content is greater than or equal to 70%. The modified isocyanate disclosed by the invention has good storage stability, and slow-rebound polyurethane foam prepared from the modified isocyanate has fine open pores and has the advantages of high latitude, good tear resistance and good sound absorption and insulation effects.

Description

Technical Field

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

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

[0003] In view of the defects of closed-cell shrinkage and other defects of traditional slow-rebound foam products, the existing technical solutions mainly include the following three aspects: (1) By selecting the type of silicone oil in the composite polyether (combination A material), the surface tension of the cells generated during the foaming reaction is controlled, and the open and closed cell properties of the cells are adjusted; (2) By designing the catalyst system in the composite polyether, the competitive reaction rate between water and polyether polyol and isocyanate in the composite polyether is adjusted, thereby controlling the cell structure and achieving an open cell state; (3) By selecting the chain segment structure composition of the composite polyether polyol (combination A material) and the functionality and structure of the isocyanate in the isocyanate component (combination B material), an open cell system is designed.

[0004] Chinese patent document CN 109021193 A discloses a highly breathable polyurethane foam prepared with MDI as raw material, which does not contain TDI components and is safe and environmentally friendly. Although the prepared polyurethane foam has good open-cell air permeability, water permeability and suitable viscoelasticity, the tear strength of the foam is low (less than 2N / cm), which does not meet the foam physical property requirements of the automotive industry.

[0005] Chinese patent document CN 116239746 A discloses a viscoelastic polyurethane foam and its preparation method and use, which mainly solves the problems of poor low-frequency sound absorption performance and hardening at low temperatures in the prior art polyurethane foam; wherein the isocyanate content in component B is 26-31%, and includes 60-90 parts of modified MDI and 10-40 parts of polymerized MDI by weight; 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, but the compression permanent deformation of the obtained foam is poor, and its application in automotive acoustic carpets has limitations. At the same time, the flow filling property is poor, and the density of the actually produced product is high, which cannot meet the current development trend of lightweight automobiles.

[0006] So, how to prepare open-cell, slow-rebound black material (isocyanate component) from the third aspect, and then select the appropriate type and amount of silicone oil to design an open-cell, slow-rebound system so that the formula has high tolerance, the foaming ratio, foam appearance and performance indicators meet the actual needs of customers, is a direction worthy of further research. Summary of the invention

[0007] The purpose of the present invention is to provide a modified isocyanate and a preparation method and application thereof to address the problems of poor appearance, high closed-cell rate, insufficient flow and filling properties, and poor physical properties of foam products prepared from existing modified MDI prepolymers; the modified isocyanate has good storage stability, and the slow-rebound polyurethane foam prepared therefrom has fine open pores, high tolerance, good tearing performance, and good sound absorption and insulation effects.

[0008] In order to achieve the above object, the present invention provides the following technical solutions: In a first aspect, a modified isocyanate is provided, wherein the raw material components thereof include, by weight: 70 to 94 parts (e.g., 72 parts, 74 parts, 75 parts, 80 parts, 85 parts, 90 parts, 92 parts) of an organic isocyanate; 6 to 30 parts (e.g., 7 parts, 8 parts, 10 parts, 12 parts, 15 parts, 20 parts, 24 parts, 25 parts, 28 parts) of a polyether polyol i; in, The polyether polyol i is a polyether polyol obtained by random copolymerization of EO / PO monomers and EO end-capping, or a polyether polyol obtained by block copolymerization of PO monomers and EO end-capping, or a mixture of the two; The average molecular weight of the polyether polyol i is 2000-10000 (for example, 2500, 3000, 4000, 4500, 5000, 5500, 6000, 7000, 8000, 8500, 9000, 9500), the functionality is 2-4 (for example, 2.5, 3, 3.5), the EO mass percentage is 5-29wt% (for example, 6wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 28wt%), and the PO mass percentage is 71-95wt% (for example, 72wt%, 74wt%). , 75wt%, 80wt%, 85wt%, 90wt%, 92wt%, 94wt%), the hydroxyl value is 20-80mgKOH / g (for example, 22mgKOH / g, 25mgKOH / g, 30mgKOH / g, 35mgKOH / g, 40mgKOH / g, 50mgKOH / g, 55mgKOH / g, 60mgKOH / g, 70mgKOH / g, 75mgKOH / g), and the primary hydroxyl content is greater than or equal to 70% (for example, 72%, 74%, 75%, 76%, 80%, 82%, 85%, 90%, 92%, 94%, 95%, 96%).

[0009] 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, for example, it can be selected from one or more of glycerol, trimethylolpropane or tetrapentanol.

[0010] According to the modified isocyanate provided by the present invention, in some embodiments, the mass percentage of isocyanate in the modified isocyanate is 22-32wt%, for example, 24wt%, 25wt%, 26wt%, 28wt%, 30wt%, 31wt%.

[0011] In some embodiments, the functionality of the modified isocyanate is 2.2-2.8, for example, 2.4, 2.5, 2.6, 2.7.

[0012] According to the modified isocyanate provided by the present invention, in some embodiments, the organic isocyanate includes the following components in parts by weight: 2,4-diphenylmethane diisocyanate, 0 to 20 parts (e.g., 1 part, 2 parts, 4 parts, 5 parts, 8 parts, 10 parts, 14 parts, 16 parts, 18 parts); 4,4'-diphenylmethane diisocyanate, 35-65 parts (e.g., 40 parts, 45 parts, 50 parts, 55 parts, 60 parts); and Polymethylene polyphenyl isocyanate, 30 to 55 parts (e.g., 35 parts, 40 parts, 45 parts, 50 parts).

[0013] According to the modified isocyanate provided by the present invention, in some embodiments, based on the total mass fraction of the organic isocyanate and the 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.

[0014] In a second aspect, a method for preparing the modified isocyanate as described above is provided, comprising the following steps: (1) under the protection of an inert gas (such as nitrogen), an organic isocyanate, a polyether polyol i and an optional antioxidant are mixed, and then a carbamate modification reaction is carried out at 55 to 90° C. (e.g., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C.) to obtain a reaction material; (2) Sampling the reaction material as described above for testing, when the mass percentage of isocyanate reaches 22-32%, stopping the reaction; then reducing the temperature of the system (the reaction material) to 40-70° C. (e.g., 50° C., 60° C., 65° C.), stirring for 2-4 hours (e.g., 2.5 hours, 3 hours, 3.5 hours), terminating the reaction, and obtaining the modified isocyanate.

[0015] In a third aspect, there is provided a use of the modified isocyanate as described above or the modified isocyanate prepared by the preparation method as described above in an automotive slow-rebound foam product.

[0016] According to the application provided by the present invention, in some embodiments, the slow-rebound foam is obtained by mixing component A and component B for reaction; wherein, The component A is an isocyanate reactive component, and the component B is the modified isocyanate; The isocyanate index is 50-90% (i.e., the ratio of 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%.

[0017] 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 foaming agent; wherein, The polyether polyol ii is selected from one or more of the soft foam polyols, with an average functionality of 2 to 4, a hydroxyl value of 20 to 150 mgKOH / g (for example, 25 mgKOH / g, 40 mgKOH / g, 50 mgKOH / g, 60 mgKOH / g, 80 mgKOH / g, 100 mgKOH / g, 120 mgKOH / g, 130 mgKOH / g, 145 mgKOH / g), and an ethylene oxide content of 30 to 90% (for example, 35%, 40%, 50%, 60%, 80%, 85%); 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'-di(2-hydroxypropyl)-1,3-propylenediamine, dimethylaminopropylamine, N,N'-dimethylethanolamine, bis(3-dimethylaminopropyl)aminoisopropanol, tetramethyldipropylenetriamine, pentamethyldiethylenetriamine, triethylenediamine, dimethylaminopropylamine, N,N,N'-trimethyl-N'-hydroxyethyl bisaminoethyl ether, bis(3-dimethylaminopropyl)aminoisopropanol, tetramethyldipropylenetriamine and 3,3'-iminobis(N,N-dimethylpropylamine); The surfactant is selected from polysiloxane-polyalkylene oxide block copolymers; The foaming agent is selected from one or more of water, CO2, dichlorofluoroethane, butane, n-pentane, cyclopentane and isopentane, preferably water.

[0018] According to the application provided by the present invention, in some embodiments, in the isocyanate reactive component (component A), based on 100 parts by weight of polyether polyol ii, the weight parts of each raw material are as follows: Catalyst, 0.5-2.5 parts (e.g., 0.6 parts, 0.8 parts, 1.0 parts, 1.5 parts, 2.0 parts); Surfactant, 0.2-2.0 parts (e.g., 0.4 parts, 0.5 parts, 0.8 parts, 1.0 parts, 1.5 parts, 1.8 parts); Blowing agent, 1.5-6.0 parts (e.g., 1.8 parts, 2.0 parts, 2.5 parts, 3.0 parts, 4.0 parts, 5.0 parts, 5.5 parts).

[0019] In the present invention, the specific steps of the application may be: Prepare component A according to the formula of each component, then pour the modified isocyanate as component B into the prepared component A, stir for 5-8s at 2000-3000r / min, and then pour the obtained liquid into the foaming mold for foaming and sample preparation, wherein the mold temperature can be 60-65°C, the demoulding time can be 1-2min, and the overall molding density can be 40-80kg / m 3, and then after 24-48 hours of maturation, the slow-rebound polyurethane foam is obtained.

[0020] In a fourth aspect, a slow-rebound foam for automobiles prepared by the above application is provided. For example, the slow-rebound foam for automobiles has a loss factor equal to or greater than 0.3, a compression set (90%) less than or equal to 10%, and a tear strength equal to or greater than 2 N / cm.

[0021] 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, which is actually incompatible with each other; polyurethane products are divided into soft segments and hard segments, the hard segment is a carbamate with a larger polarity, and the soft segment is a polyether segment, wherein the polarity of the EO polyether segment is larger than that of the PO polyether segment, and the oxygen atom is exposed, and its lone pair of electrons can form hydrogen bonds with the hydrogen atoms of the hard segment carbamate, so that the soft segment polyether and the hard segment carbamate form a microphase mixture, thereby increasing the glass transition temperature of the soft segment, and the PO polyether segment has a large difference in polarity with the hard segment carbamate due to the steric hindrance of the methyl group, so that the formation of microphase mixing is difficult, and the phase separation is very good; therefore, controlling the EO content of the polyether polyol in the modified B material (modified isocyanate component) within an appropriate range can affect the degree of phase separation of the soft and hard segments of the polyurethane foam, thereby affecting the degree of open and closed pores of the foam. On the contrary, the slow rebound combination A (mainly comprising polyether polyol components) is a polyether system with a high EO content.

[0022] The polyether polyol used in the modified isocyanate of the present invention is a selected high PO content polyether, which can affect the phase separation of the slow rebound combination A material polyol and the hard segment urethane used for preparing the polyurethane foam. On this basis, by optimizing the EO content in the polyether polyol used by the modified isocyanate, the inventor found that the polyether polyol with an overall EO content of no more than 30wt% in the modified isocyanate component can achieve the effect of opening the cells of the slow rebound system, and as the PO segments increase, the opening effect is more obvious. If the polyether polyol with an overall EO content of no more than 30wt% used in the modified isocyanate component is selected to be added to the combination A material of the slow rebound polyurethane foam, there will be a defect of stratification due to poor compatibility. Therefore, the present invention is mainly modified by selecting a polyether polyol with a specific polyether structure and EO content and prepolymerizing with isocyanate, and the soft and hard segment phase separation degree is regulated by the arrangement of specific polyether EO segments and PO segments and the segment ratio to achieve the state of polyurethane foam opening.

[0023] The beneficial effects of the technical solution of the present invention are at least: In the process of preparing automotive viscoelastic foam, under the same isocyanate index and with the same slow-rebound combined polyether (component A in polyurethane foam), compared with the mixed isocyanate composition not modified by polyether polyol, the foam prepared by the modified isocyanate of the present invention is more open-celled, the surface pores are more delicate, and the foam feels good; 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 prepared foam is also more open-celled, and has good performance in physical properties (such as compression permanent deformation that is of great concern to automotive carpet products); in terms of fluidity, the foam prepared by using the modified isocyanate of the present invention has better filling properties, and the preparation of low-density products can be achieved; in terms of storage stability, the modified isocyanate of the present invention is still clear and transparent without crystallization after being stored at 0°C for 3 months. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The shrinkage states of the foams at different molding densities are shown, from left to right: no shrinkage state, slight shrinkage state, and severe shrinkage state. DETAILED DESCRIPTION

[0025] In order 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 embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. For those who do not specify specific conditions in the embodiments, they are carried out according to normal conditions or the conditions recommended by the manufacturer.

[0026] Test method: (1) The storage stability evaluation method of the modified isocyanate in the present invention is as follows: The modified isocyanate sample was sealed in a 500 mL iron bottle and stored at 0°C for 3 months to observe its crystallization state and whether it was bulging. (2) The performance testing method of the molded slow-rebound foamed product of the present invention is as follows: Tensile strength (kPa): GB / T 6344-2008; Elongation at break (%): GB / T 6344-2008; Tear strength (N / cm): GB / T 10808-2006; Compression set (%): GB / T 6669-2008; Compression hardness (KPa): GB / T 29901-2013; Loss factor: Use a dynamic loss factor tester and test according to Z-Nr 1933 613.3 standard; Sound absorption coefficient: GB / T 18696.1-2004, the test range of the equipment is 100-10000Hz; the test samples are cut into circular samples with a diameter of 9.6cm and 3cm respectively, 9.6cm is used to test the low-frequency sound absorption coefficient, and 3cm is used to test the high-frequency sound absorption coefficient. The sound absorption coefficients at 500Hz, 630Hz, 800Hz, 1000Hz, 1250Hz, 1600Hz, 2000Hz, 2500Hz, 3150Hz, 4000Hz, 5000Hz, 6300Hz and 10000Hz are measured respectively.

[0027] Table 1 Organic isocyanate raw materials used in modified isocyanates and their sources

[0028] Table 2 Polyether polyol raw materials used in modified isocyanate and their sources

[0029] Table 3 Raw materials and sources of component A in slow-rebound foam

[0030] [Example 1] The preparation method of modified isocyanate comprises the following steps: (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 were added to a 5 L glass reactor, heated to 75° C., and stirred until they were completely melted; then the reactor was heated to 80° C., 258 g of polyether polyol A was added, and the reaction was stirred for 2 hours to obtain a reaction mass; (2) The reaction material is sampled and tested. When the mass percentage of isocyanate reaches 22-32%, the reaction is stopped. Then, the reaction material in the reactor is cooled to 60° C. and stirred for 2 hours to terminate the reaction to obtain modified isocyanate.

[0031] The performance of the modified isocyanate was evaluated and the results are shown in Table 4.

[0032] Preparation of slow-rebound polyurethane foam: Component A was prepared according to the raw material formula shown in Table 6, and then the modified isocyanate prepared as above was poured into the prepared component A as component B according to the dosage ratio shown in Table 6, stirred at 3000r / min for 5-8s, and then the obtained material liquid was poured into the foaming mold for foaming and sample preparation, wherein the mold temperature was 65°C, the demoulding time was 2min, and the overall molding density was 65kg / m 3After the obtained polyurethane foam was matured for 48 hours, the performance was tested. The physical property test results are shown in Table 7.

[0033] [Examples 2 to 7] The preparation methods of the modified isocyanates in Examples 2 to 7 refer to Example 1, except that the types of the various reaction raw materials, raw material ratios and other parameters of the modified isocyanates are different, as shown in Table 4; modified isocyanates are obtained.

[0034] The performance of the modified isocyanate was evaluated and the results are shown in Table 4.

[0035] Preparation of slow-rebound polyurethane foam: Component A was prepared according to the raw material formula shown in Table 6, and then the modified isocyanate prepared as above was poured into the prepared component A as component B according to the dosage ratio shown in Table 6, stirred at 3000r / min for 5-8s, and then the obtained material liquid was poured into the foaming mold for foaming and sample preparation, wherein the mold temperature was 65°C, the demoulding time was 2min, and the overall molding density was 65kg / m 3 After the obtained polyurethane foam was matured for 48 hours, the performance was tested. The physical property test results are shown in Table 7.

[0036] Table 4 Components of modified isocyanate, their dosage and stability test results

[0037] [Comparative Example 1] In Comparative Example 1, the modified isocyanate is commercially available WANNATE 8223B, wherein WANNATE 8223B is an isocyanate composition that does not contain polyether polyol, and its main component is a mixture of 2,4-MDI, 4,4'-MDI and polymethylene polyphenyl isocyanate.

[0038] The performance of the modified isocyanate was evaluated, and the results are shown in Table 5.

[0039] Preparation of slow-rebound polyurethane foam: Prepare component A according to the raw material formula shown in Table 6, then pour the modified isocyanate as component B into the prepared component A according to the dosage ratio shown in Table 6, stir for 5-8s at 3000r / min, and then pour the resulting liquid into the foaming mold for foaming and sample preparation, wherein the mold temperature is 65°C, the demoulding time is 2min, and the overall molding density is 65kg / m 3 After the obtained polyurethane foam was matured for 48 hours, the performance was tested. The physical property test results are shown in Table 7.

[0040] [Comparative Example 2] In this comparative example 2, the modified isocyanate uses commercially available WANNATE 80339, wherein the main component of WANNATE 80339 is a product obtained by modifying a mixture of 2,4-MDI, 4,4'-MDI and polymethylene polyphenyl isocyanate by polyether polyol, wherein the polyether polyol is a polyether polyol with a high EO content, and the EO content is greater than 70wt%.

[0041] The performance of the modified isocyanate was evaluated, and the results are shown in Table 5.

[0042] Preparation of slow-rebound polyurethane foam: Prepare component A according to the raw material formula shown in Table 6, then pour the modified isocyanate as component B into the prepared component A according to the dosage ratio shown in Table 6, stir for 5-8s at 3000r / min, and then pour the resulting liquid into the foaming mold for foaming and sample preparation, wherein the mold temperature is 65°C, the demoulding time is 2min, and the overall molding density is 65kg / m 3 After the obtained polyurethane foam was matured for 48 hours, the performance was tested. The physical property test results are shown in Table 7.

[0043] [Comparative Example 3] The preparation method of the modified isocyanate in Comparative Example 3 refers to Example 1, except that: the parameters such as the reaction raw materials of the modified isocyanate (the polyether polyol used is a short-chain polyether polyol), the raw material ratio, etc. are different, as shown in Table 5; and the modified isocyanate is obtained.

[0044] The performance of the modified isocyanate was evaluated and the results are shown in Table 5.

[0045] Preparation of slow-rebound polyurethane foam: Component A was prepared according to the raw material formula shown in Table 6, and then the modified isocyanate prepared as above was poured into the prepared component A as component B according to the dosage ratio shown in Table 6, stirred at 3000r / min for 5-8s, and then the obtained material liquid was poured into the foaming mold for foaming and sample preparation, wherein the mold temperature was 65°C, the demoulding time was 2min, and the overall molding density was 65kg / m 3 After the obtained polyurethane foam was matured for 48 hours, the performance was tested. The physical property test results are shown in Table 7.

[0046] [Comparative Example 4] The preparation method of the modified isocyanate in Comparative Example 4 refers to Example 1, except that: the parameters such as the reaction raw materials of the modified isocyanate (the polyether polyol used is pure EO polyether polyol), the raw material ratio, etc. are different, as shown in Table 5; and the modified isocyanate is obtained.

[0047] The performance of the modified isocyanate was evaluated and the results are shown in Table 5.

[0048] Preparation of slow-rebound polyurethane foam: Component A was prepared according to the raw material formula shown in Table 6, and then the modified isocyanate prepared as above was poured into the prepared component A as component B according to the dosage ratio shown in Table 6, stirred at 3000r / min for 5-8s, and then the obtained material liquid was poured into the foaming mold for foaming and sample preparation, wherein the mold temperature was 65°C, the demoulding time was 2min, and the overall molding density was 65kg / m 3 After the obtained polyurethane foam was matured for 48 hours, the performance was tested. The physical property test results are shown in Table 7.

[0049] Table 5 Components in modified polyisocyanate, their dosage and stability test results

[0050] Table 6 Raw material formula of slow rebound polyurethane foam

[0051] Note: The modified isocyanate in Table 6 refers to the modified isocyanate prepared or provided in each embodiment and comparative example.

[0052] Table 7 Test results of slow-rebound polyurethane foam properties of Examples 1 to 7 and Comparative Examples 1 to 4

[0053] From the physical property results, under the same isocyanate index conditions, the polyurethane foam prepared by the modified isocyanate obtained in each embodiment has a lower free bubble density, and its tensile strength is not significantly increased as a whole, but the elongation at break and the tear strength are significantly improved; in automotive soft foam products, the tear performance requirement for PU materials is generally above 2.0N / cm. The B component (modified isocyanate) of the present invention can greatly improve the problem of poor tearing performance of slow-rebound soft foam products. At the same time, due to the selection of polyether polyols in the B component (modified isocyanate), the open porosity of the polyurethane foam system is very high, and the compression permanent deformation of the foam is greatly improved, especially in automotive carpet products. The polyurethane foam product can remain unchanged after long-term use.

[0054] In Comparative Example 1, the isocyanate component is an isocyanate composition that does not contain polyether polyols. The free bubble density of the polyurethane foam prepared therefrom is high, the elongation at break and the tear strength are significantly poor, and the compression permanent deformation of the foam is also poor. In Comparative Example 2, the isocyanate component is a product after the isocyanate mixture is modified by a polyether polyol with a high EO content. The elongation at break and the tear strength of the polyurethane foam prepared therefrom are significantly poor, and the compression permanent deformation of the foam is also poor. In Comparative Example 3, the isocyanate component is a product after the isocyanate mixture is modified by pure PO polyether polyols. The free bubble density of the polyurethane foam prepared therefrom is high, the elongation at break and the tear strength are significantly poor, and the compression permanent deformation of the foam is also poor. In Comparative Example 4, the isocyanate component is a product after the isocyanate mixture is modified by pure EO polyether polyols. The storage stability of the modified isocyanate is very poor, and the free bubble density of the polyurethane foam prepared therefrom is high, the elongation at break and the tear strength are significantly poor, and the compression permanent deformation of the foam is also poor.

[0055] Table 8 Comparison of open and closed cell properties of polyurethane foams under different isocyanate indices

[0056] As shown in Table 8, the polyurethane foams prepared by using the modified isocyanates obtained in Examples 1, 5, and 7 at different isocyanate indices do not shrink, indicating that the polyurethane foams prepared by using the modified isocyanates prepared in the present invention have a very high index tolerance in terms of foam opening. When the isocyanate index is between 55 and 75, the obtained molded foams have a very high cell opening rate, the foams have a full appearance, distinct corners, and a very good pressing rebound effect; while the polyurethane foams prepared by using the modified isocyanates of Comparative Examples 1-3 at different isocyanate indices have a shrinkage phenomenon when the isocyanate index is between 60 and 75, and the shrinkage degree becomes more and more serious as the isocyanate index increases, indicating that the polyurethane foams prepared by using the commercially available WANNATE 8223B and WANNATE 80339 have a very low cell opening rate, and as the index increases, the foam closed cell rate increases, resulting in different degrees of shrinkage of the molded foams, wrinkles on the surface, and mechanical foam breaking is required to open the cells.

[0057] In addition, the comparison of open and closed cell properties of the prepared foams with increasing molding density was further studied, as shown in Table 9.

[0058] Table 9 Comparison of open and closed cell properties of polyurethane foams obtained at different molding densities

[0059] As shown in Table 9, at different molding densities, the polyurethane foams prepared by using the modified isocyanate obtained in Examples 1, 5, and 7 do not shrink, indicating that the polyurethane foams prepared by using the modified isocyanate obtained in the present invention have a very high molding density tolerance in terms of foam opening. 3 The obtained molded foam has a high pore opening rate, a full foam appearance, distinct corners, and a good pressing rebound effect; while the polyurethane foams prepared by using the modified isocyanate of Comparative Examples 1-3 at different molding densities have a high foam opening rate at a molding density of 50-80 kg / m 3 The foam will shrink during the molding process, and the shrinkage becomes more and more serious as the molding density increases. This shows that the open cell rate of the polyurethane foam prepared by using the commercially available WANNATE8223B and WANNATE 80339 is very low, and as the molding density increases, the closed cell rate of the foam increases, resulting in different degrees of shrinkage of the molded foam and wrinkles on the surface.

[0060] Among them, the state of no contraction, the state of slight contraction and the state of severe contraction, please see Figure 1 The schematic shown.

[0061] Fluidity investigation: The flow and filling properties of materials in molds with certain shapes during the preparation of polyurethane foam were studied separately.

[0062] Table 10 Comparison of flow and filling properties

[0063] The flowability and filling properties of the materials in a certain mold were compared in the process of preparing polyurethane foam using the modified isocyanates of Example 1, Example 5 and Example 7 as raw materials with those of Comparative Examples 1-2 and Comparative Example 4; the volume of the mold used was 1.3L, and the minimum foam mass required to fill the mold was the limit filling weight. From the comparison results shown in Table 10, the modified isocyanate of the present invention has good fluidity due to its relatively low functionality, the small polarity of the modified polyether polyol segment, and the low viscosity, which ultimately makes the material have good mold filling properties, less foam mass required to fill the same volume of mold, and lower foam density, which better caters to the current development trend of lightweight and low cost of automobiles.

[0064] Sound absorption effect study: The sound absorption effect of the polyurethane foam prepared by using the modified isocyanate of each embodiment and comparative example was studied; the polyurethane foam prepared by using the modified isocyanate of the present invention is very open-celled, and the obtained foam pores are fine, so its sound absorption effect has obvious advantages. The sound absorption result test data is shown in Table 11.

[0065] Table 11 Test data of sound absorption effect of polyurethane foam

[0066] By using the modified isocyanate of the present invention, since the pore opening rate of the formula system is high, sound waves can enter the pores and refract the sound waves in the pores. In addition, the soft pore walls produced by the high EO content polyether in the A component convert the vibration energy of the sound waves entering the pore walls into heat energy and are absorbed by the pore walls. Therefore, the sound absorption effect is very excellent, and the sound absorption coefficient of the foam prepared by the modified isocyanate currently available on the market is higher at both low and medium and high frequencies.

[0067] It can be seen that the viscoelastic polyurethane foam prepared by the modified isocyanate of the present invention has good index tolerance and density tolerance, flow filling property, as well as excellent sound absorption performance, damping performance, tearing performance and good compression permanent deformation, and can be used in the industrial application of sound-absorbing carpets, front surrounds and acoustic packages of automotive interior parts.

[0068] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the spirit of the present invention.

Claims

1. A modified isocyanate, characterized in that: The raw material components include, by weight: 70 to 94 parts of organic isocyanate; 6 to 30 parts of polyether polyol i; in, The polyether polyol i is a polyether polyol obtained by random copolymerization of EO / PO monomers and EO end-capping, or a polyether polyol obtained by block copolymerization of PO monomers and EO end-capping, or a mixture of the two; The polyether polyol i has an average molecular weight of 2000-10000, a functionality of 2-4, an EO mass percentage of 5-29wt%, a PO mass percentage of 71-95wt%, a hydroxyl value of 20-80 mgKOH / g, and a primary hydroxyl content of greater than or equal to 70%.

2. The modified isocyanate according to claim 1, characterized in that The mass percentage of isocyanate in the modified isocyanate is 22-32wt%.

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

8.

4. The modified isocyanate according to claim 1, characterized in that In parts by weight, the organic isocyanate comprises the following components in parts by weight: 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, characterized in that Based on the total mass fraction of the organic isocyanate and the polyether polyol i, the modified isocyanate further includes an antioxidant, and the content of the antioxidant is 0 to 800 ppm.

6. The method for preparing the modified isocyanate according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Under the protection of an inert gas, an organic isocyanate, a polyether polyol i and an optional antioxidant are mixed, and then a urethane modification reaction is carried out at 55 to 90° C. to obtain a reaction material; (2) Sampling the reaction material as described above for testing, when the mass percentage of isocyanate reaches 22-32%, stopping the reaction; then lowering the temperature of the system to 40-70° C., stirring for 2-4 hours, and terminating the reaction to obtain the modified isocyanate.

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

8. The use according to claim 7, characterized in that: The slow-rebound foam is obtained by mixing component A and component B to react; wherein, The component A is an isocyanate reactive component, and the component B is the modified isocyanate; The isocyanate index is 50-90%.

9. The use according to claim 8, characterized in that: The isocyanate reactive components include polyether polyol ii, catalyst, surfactant, and foaming agent; wherein, The polyether polyol ii is selected from one or more of the soft foam polyols, and has an average functionality of 2 to 4, a hydroxyl value of 20 to 150 mgKOH / g, and an ethylene oxide content of 30 to 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'-di(2-hydroxypropyl)-1,3-propylenediamine, dimethylaminopropylamine, N,N'-dimethylethanolamine, bis(3-dimethylaminopropyl)aminoisopropanol, tetramethyldipropylenetriamine, pentamethyldiethylenetriamine, triethylenediamine, dimethylaminopropylamine, N,N,N'-trimethyl-N'-hydroxyethyl bisaminoethyl ether, bis(3-dimethylaminopropyl)aminoisopropanol, tetramethyldipropylenetriamine and 3,3'-iminobis(N,N-dimethylpropylamine); The surfactant is selected from polysiloxane-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 automotive slow-rebound foam obtained by the application according to any one of claims 7 to 9.

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