A kind of viscoelastic polyurethane foam and its preparation method and application

Abstract

The present invention relates to the technical field of polyurethane foam materials, and provides a viscoelastic polyurethane foam and a preparation method and application thereof. The viscoelastic polyurethane foam prepared by the preparation method of the present invention has the characteristics of fast maturation and high production efficiency, and can simultaneously obtain a viscoelastic polyurethane foam with low density and good physical properties, and can meet the technical requirements of automobile sound insulation pad foam. The preparation method obtains the viscoelastic polyurethane foam by reacting a material including an isocyanate reactive component and an isocyanate; wherein the isocyanate reactive component includes a polyether polyol composition and a foaming agent; the polyether polyol composition includes polyether polyol A1 and polyether polyol A2; the amount of the polyether polyol A1 is 25 to 65 parts by mass, the amount of the polyether polyol A2 is 30 to 70 parts by mass, and the amount of the foaming agent is 3 to 6 parts by mass.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane foam materials, and in particular to a viscoelastic polyurethane foam and a preparation method and application thereof. Background Art

[0002] Polyurethane foam is currently widely used in vehicles such as automobiles, high-speed trains, and airplanes. It is usually used to prepare parts such as car carpets, front panels, coat racks, and spare tire mats. In addition to decorating the interior of the car, it also has the effects of sound absorption, noise reduction, and shock absorption, while improving the comfort of the car interior. With the development needs of the automotive industry for lightweight, intelligent, comfortable, safe and environmentally friendly, traditional high-resilience polyurethane sponges can no longer meet the current comfort requirements. Viscoelastic polyurethane foam has better energy absorption, shock absorption, and sound absorption effects, which can greatly improve the comfort of the car.

[0003] Chinese patent CN1257203C discloses a viscoelastic polyurethane foam, which uses polyether A with a functionality of 3, an EO content of 75%wt, and a hydroxyl value of 42mgKOH / g, polyether B with a functionality of 3, an EO content of 28%wt, and a hydroxyl value of 28mgKOH / g, and PEG-200 as main raw materials. The prepared foam has obvious defects in performance, such as high density, low tear strength and low tensile strength.

[0004] Chinese patent application CN116239746A discloses a method for preparing viscoelastic polyurethane foam, which illustrates that viscoelastic polyurethane foam has obvious advantages over high-resilience polyurethane foam in terms of sound absorption performance. However, its preparation process also has the obvious defect of slow maturation, resulting in low production efficiency and increased costs. At the same time, the specific performance of the prepared foam is not pointed out.

[0005] Chinese patent CN1175020C discloses a method for preparing viscoelastic polyurethane foam. The foam prepared by the method has a density of only 65 kg / m 3 The tensile strength and tear strength of the foam can meet the requirements of automotive parts, which greatly increases the production cost and cannot meet the actual production needs.

[0006] Chinese patent application CN115803355A discloses a polyurethane foam for improving acoustic performance, but its foam density is less than 25kg / m 3 , and the foam tensile strength and elongation at break are very low. It is obviously a semi-rigid polyurethane foam, which is far from meeting the technical requirements of automotive sound insulation pads.

[0007] Therefore, it is necessary to develop a preparation technology for viscoelastic polyurethane foam in order to simultaneously meet the technical requirements of automotive parts such as automotive sound insulation pad foam (for example, tensile strength ≥90 kPa, elongation at break ≥90%, tear strength ≥1.7 N / cm, etc.) and the requirement of short aging time to improve production efficiency. Summary of the invention

[0008] In view of at least one shortcoming of the prior art, the present invention provides a viscoelastic polyurethane foam and a preparation method and application thereof. The viscoelastic polyurethane foam prepared by the preparation method of the present invention has the characteristics of fast maturation and high production efficiency. At the same time, it can obtain a viscoelastic polyurethane foam with low density and good physical properties, and can meet the technical requirements of automobile sound insulation pad foam.

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

[0010] The present invention provides a method for preparing a viscoelastic polyurethane foam, wherein the viscoelastic polyurethane foam is obtained by reacting a material including an isocyanate reactive component and an isocyanate; wherein the isocyanate reactive component includes a polyether polyol composition and a foaming agent;

[0011] The polyether polyol composition comprises polyether polyol A1 and polyether polyol A2;

[0012] The hydroxyl values ​​of the polyether polyol A1 and the polyether polyol A2 are 24-42 mgKOH / g respectively; based on the total amount of primary hydroxyl groups and secondary hydroxyl groups, the content of primary hydroxyl groups is ≥80wt% respectively;

[0013] The polyether polyol A1 has an average functionality of 3-4 and is a polyether polyol using propylene oxide and ethylene oxide as polymerization monomers and capped with ethylene oxide. Based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomers is 50-90wt%;

[0014] The polyether polyol A2 has an average functionality of 3-4 and is a polyether polyol using propylene oxide and ethylene oxide as polymerization monomers and capped with ethylene oxide. Based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomers is 20-50wt%;

[0015] In the isocyanate reactive component, the amount of the polyether polyol A1 is 25 to 65 parts by mass, the amount of the polyether polyol A2 is 30 to 70 parts by mass, and the amount of the foaming agent is 3 to 6 parts by mass.

[0016] Preferably, the hydroxyl value of the polyether polyol A1 is 28-42 mgKOH / g; based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomer is 70-90wt%; based on the total amount of primary hydroxyl and secondary hydroxyl, the content of primary hydroxyl is ≥85wt%;

[0017] The hydroxyl value of the polyether polyol A2 is 24-35 mgKOH / g; based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomer is 20-40wt%; based on the total amount of primary hydroxyl groups and secondary hydroxyl groups, the content of primary hydroxyl groups is ≥85wt%.

[0018] Preferably, the polyether polyol A1 uses one or more of an alcohol compound with a functionality of 3 and an alcohol compound with a functionality of 4 as an initiator.

[0019] And / or, the polyether polyol A2 uses one or more of an alcohol compound with a functionality of 3 and an alcohol compound with a functionality of 4 as an initiator.

[0020] Preferably, the initiator of the polyether polyol A1 is one or more of glycerol, trimethylolpropane or tetrapentanol;

[0021] And / or, the initiator of the polyether polyol A2 is one or more of glycerol, trimethylolpropane or tetrapentanol.

[0022] Preferably, in the isocyanate-reactive component, the amount of polyether polyol A1 is 30 to 60 parts by mass, the amount of polyether polyol A2 is 40 to 65 parts by mass, and the amount of the blowing agent is 3.5 to 5.5 parts by mass.

[0023] Preferably, the isocyanate reactive component further comprises 0.1 to 1.5 parts by mass of a catalyst and 0.2 to 1.5 parts by mass of a surfactant;

[0024] and / or, the mass ratio of the isocyanate-reactive component to the isocyanate is 100:30-70;

[0025] And / or, the NCO content of the isocyanate is 24-32wt%.

[0026] In some embodiments, the isocyanate is selected from one or more of polyphenylmethane polyisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate and polyol-modified isocyanate prepolymer;

[0027] And / or, the foaming agent is selected from water, CO 2 , one or more of alkane foaming agents, chlorine-containing foaming agents, and fluorine-containing foaming agents;

[0028] And / or, the catalyst is selected from one or more of an amine catalyst and an organic metal catalyst.

[0029] Furthermore, the preparation steps of the viscoelastic polyurethane foam include:

[0030] uniformly mixing the raw materials of the isocyanate reactive component to obtain a first mixed material, mixing the first mixed material with the isocyanate to obtain a second mixed material, and transferring the second mixed material to a mold for a foaming reaction;

[0031] Preferably, the first mixed material and the isocyanate are mixed at 20-40° C.;

[0032] Preferably, the foaming reaction time is 60-100s;

[0033] Preferably, the temperature of the mold is 50-80°C.

[0034] The present invention also provides a viscoelastic polyurethane foam prepared by the preparation method described above.

[0035] The present invention also provides the use of the viscoelastic polyurethane foam described above in the preparation of automobile parts, wherein the automobile parts include automobile sound insulation pads;

[0036] Alternatively, the automobile parts include one or more of an automobile carpet, a front wall, a wheel cover, a coat rack and a spare tire mat.

[0037] The technical solution provided by the present invention has the following beneficial effects:

[0038] The viscoelastic polyurethane foam prepared by the method of the present invention has the characteristics of fast maturation, and can also obtain viscoelastic polyurethane foam with good comprehensive performance, which is particularly suitable for producing automobile sound insulation pads. The obtained foam material can have a suitable low density, as well as good tensile strength, elongation at break, tear strength and loss factor. For example, a density of 50 to 80 kg / m 3 , viscoelastic polyurethane foam with tensile strength ≥90kPa, elongation ≥90%, tear strength ≥1.7N / cm, and loss factor of 0.25 to 0.7. DETAILED DESCRIPTION

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0040] The terms “first”, “second”, etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0041] In one aspect, the present invention provides a method for preparing a viscoelastic polyurethane foam, wherein the viscoelastic polyurethane foam is obtained by reacting a material including an isocyanate reactive component and an isocyanate; wherein the isocyanate reactive component includes a polyether polyol composition and a foaming agent;

[0042] The polyether polyol composition comprises polyether polyol A1 and polyether polyol A2;

[0043] The hydroxyl values ​​of the polyether polyol A1 and the polyether polyol A2 are 24-42 mgKOH / g respectively; in the polyether polyol A1 and the polyether polyol A2, the content of the primary hydroxyl group is ≥80wt% based on the total amount of the primary hydroxyl group and the secondary hydroxyl group;

[0044] The polyether polyol A1 has an average functionality of 3-4 and is a polyether polyol using propylene oxide (PO) and ethylene oxide (EO) as polymerization monomers and capped with ethylene oxide. Based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomers is 50-90wt%;

[0045] The polyether polyol A2 has an average functionality of 3-4 and is a polyether polyol using propylene oxide and ethylene oxide as polymerization monomers and capped with ethylene oxide. Based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomer is 20-50wt%;

[0046] In the isocyanate reactive component, the amount of the polyether polyol A1 is 25 to 65 parts by mass, the amount of the polyether polyol A2 is 30 to 70 parts by mass, and the amount of the foaming agent is 3 to 6 parts by mass.

[0047] The present invention adopts polyether polyol A1, polyether polyol A2 and blowing agent including the above-mentioned usage range as isocyanate reactive components to react with isocyanate to prepare viscoelastic polyurethane foam, which has fast curing characteristics, and the obtained viscoelastic polyurethane foam has both low density and good physical and mechanical properties, which can meet the production needs of sound insulation pads such as automobile front panels and carpets, improve production efficiency and reduce costs.

[0048] In a preferred embodiment, the hydroxyl value of the polyether polyol A1 is 28-42 mgKOH / g; based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomers is 70-90%; based on the total amount of primary hydroxyl groups and secondary hydroxyl groups, the content of primary hydroxyl groups is ≥85wt%;

[0049] The hydroxyl value of the polyether polyol A2 is 24-35 mgKOH / g; based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomer is 20-40%; based on the total amount of primary hydroxyl groups and secondary hydroxyl groups, the content of primary hydroxyl groups is ≥85wt%.

[0050] Preferably, the polyether polyol A1 uses one or more of an alcohol compound with a functionality of 3 and an alcohol compound with a functionality of 4 as an initiator; preferably, the polyether polyol A2 uses one or more of an alcohol compound with a functionality of 3 and an alcohol compound with a functionality of 4 as an initiator. Further preferably, the initiator of the polyether polyol A1 is one or more of glycerol, trimethylolpropane or tetrapentanol; the initiator of the polyether polyol A2 is one or more of glycerol, trimethylolpropane or tetrapentanol. The above-mentioned polyether polyols A1 and A2 can be prepared using commercially available raw materials known in the art that meet the above-mentioned requirements, or can be prepared using a polyether preparation process known in the art.

[0051] In a preferred embodiment, in the isocyanate reactive component, the amount of polyether polyol A1 is 30-60 parts by mass, the amount of polyether polyol A2 is 40-65 parts by mass, and the amount of the foaming agent is 3.5-5.5 parts by mass. The preferred dosage range is used to better balance faster aging efficiency and better comprehensive properties of the foam material, for example, a density of 50-80 kg / m 3 , foam materials with tensile strength ≥100 kPa, elongation at break ≥100%, tear strength ≥1.8 N / cm, and loss factor of 0.3 to 0.7.

[0052] Furthermore, the isocyanate reactive component further comprises 0.1 to 1.5 parts by mass of a catalyst and 0.2 to 1.5 parts by mass of a surfactant; preferably, the amount of the catalyst is 0.2 to 1.0 parts by mass, and the amount of the surfactant is 0.3 to 1.0 parts by mass.

[0053] In some embodiments, the mass ratio of the isocyanate reactive component to the isocyanate is 100:30 to 70, preferably 100:45 to 65. Further, the ratio of the equivalent number of NCO groups of the isocyanate to the equivalent number of active groups in the isocyanate reactive component (i.e., the isocyanate index) is 60-82.

[0054] Preferably, the NCO content of the isocyanate is 24-32wt%. The isocyanate can be selected from any known isocyanate, modified isocyanate, isocyanate prepolymer or more. As a preferred embodiment, the isocyanate is preferably selected from one or more of polyphenylmethane polyisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate and polyol-modified isocyanate prepolymer. The polyphenylmethane polyisocyanate described in the present invention refers to a mixture of polyphenylmethane polyisocyanates with a functionality greater than or equal to 3. Among them, the polyol-modified isocyanate prepolymer is an NCO-terminated polymer generated by the reaction of polyether polyol and isocyanate. In some examples, the isocyanate is a mixture of polyphenylmethane polyisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate and polyol-modified isocyanate prepolymer. For example, the mass ratio of polyphenylmethane polyisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate and polyol-modified isocyanate prepolymer is (20-30): (20-30): (30-45): (3-10); commercially available corresponding raw materials can be used, such as but not limited to one or more of Wanhua WANNATE 8038, WANNATE 8038K, Wanhua WANNATE 8019, etc. In some examples, the isocyanate is a mixture of polyphenylmethane polyisocyanate, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate. For example, the mass ratio of polyphenylmethane polyisocyanate, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate is (15-20): (30-40): (40-50). Commercially available corresponding raw materials can be used, such as but not limited to one or more of WANNATE 8122, WANNATE 8120, etc.

[0055] The foaming agent may be a chemical foaming agent and / or a physical foaming agent. In some embodiments, the foaming agent is selected from but not limited to water, CO 2 , alkane foaming agents, chlorine-containing foaming agents, fluorine-containing foaming agents, etc., wherein the alkane foaming agents include one or more of butane, n-pentane, cyclopentane and isopentane, etc.; the chlorine-containing foaming agents and fluorine-containing foaming agents include one or more of dichlorofluoroethane, pentafluoropropane, pentafluorobutane, dichloromethane, etc. As a preferred embodiment, the foaming agent is preferably selected from water, CO 2 , dichlorofluoroethane, butane, n-pentane, cyclopentane and isopentane, and more preferably the blowing agent is water.

[0056] In some embodiments, the catalyst is selected from one or more of an amine catalyst and an organometallic catalyst. Specifically, the amine catalyst is selected from, for example, but not limited to, one or more of bis(2-dimethylaminoethyl)ether, N,N,N'-trimethyl-N'-hydroxyethylbisaminoethylether, dimethylaminopropylamine, N,N'-dimethylethanolamine, bis(3-dimethylaminopropyl)aminoisopropanol, tetramethyldipropylenetriamine, pentamethyldiethylenetriamine and triethylenediamine. Specifically, the organometallic catalyst is selected from, for example, but not limited to, one or more of metal alkyl compounds and metal carboxylates having catalytic activity for the reaction between isocyanate-hydroxyl groups, such as metals including, but not limited to, one or more of lead, tin, titanium, antimony, mercury, etc., examples of which include, but not limited to, one or more of stannous octoate, dibutyltin dilaurate, dibutyltin diacetate, etc. As a preferred embodiment, the catalyst is preferably selected from one or more of dimethylaminopropylamine, N,N,N'-trimethyl-N'-hydroxyethylbisaminoethyl ether, bis(3-dimethylaminopropyl)aminoisopropanol and tetramethyldipropylenetriamine.

[0057] The surfactant can be of a type commonly used in the art, and there is no particular restriction on this. The surfactant can be obtained by preparation or by commercial means. The preparation method can be carried out according to the common methods of those skilled in the art; examples of surfactants obtained from commercial means include but are not limited to M-8818LO, M-8805, M-7734LF2, M7771LF2, etc. of Jiangsu Meside Chemical Co., Ltd., B8870, B8002, B8715, B8734LF2, etc. of Evonik Industries, HR-8870, HR8871, etc. of Dow Chemical. The surfactant can be used alone or in combination.

[0058] In some embodiments, the preparation step of the viscoelastic polyurethane foam includes: uniformly mixing the raw materials of the isocyanate reactive component to obtain a first mixed material, mixing the first mixed material with the isocyanate to obtain a second mixed material, and transferring the second mixed material to a mold for foaming reaction, for example, quickly injecting the second mixed material into the mold for foaming. Preferably, the first mixed material and the isocyanate are fully mixed at 20-40°C, preferably at 22-35°C, to obtain a second mixed material. In some embodiments, the foaming reaction time is 60-100s, and further for example 60-80s. Preferably, the temperature of the mold is 50-80°C.

[0059] In the preparation steps described in the present invention, specific preparation parameters and processes and other conditions that are not described in detail may adopt the preparation parameters and processes commonly used by those skilled in the art.

[0060] The present invention also provides a viscoelastic polyurethane foam prepared by the preparation method described above. In some examples, the prepared viscoelastic polyurethane foam has a molding density of 50 to 80 kg / m 3 , tensile strength ≥100 kPa, elongation greater than or equal to 100%, tear strength greater than or equal to 1.8 N / cm, loss factor of 0.3 to 0.7, suitable for foaming in a mold at 50 to 80°C, with high production efficiency.

[0061] The present invention also provides the use of the viscoelastic polyurethane foam in the preparation of automobile parts, which is particularly suitable for the preparation of automobile sound insulation pads; specifically, the automobile sound insulation pads are, for example, but not limited to, one or more of automobile carpets, front panels, wheel covers, coat racks and spare tire pads.

[0062] The present invention uses a simple raw material composition to prepare viscoelastic polyurethane foam, which has excellent physical properties and damping properties, and has low density and fast curing characteristics. It is suitable for the production process requirements of automobile sound insulation pad parts and is beneficial to reducing the production cost of the enterprise and improving the comfort of the car.

[0063] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0064] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0065] Some of the raw materials used in the following examples and comparative examples are described as follows:

[0066] Polyether polyol A1-1: glycerol is used as the initiator, propylene oxide and ethylene oxide are used as polymerization monomers and ethylene oxide is terminated, the ethylene oxide monomer content is 75wt% of the total amount of ethylene oxide monomer and propylene oxide monomer, the primary hydroxyl content is 85wt% (based on the total amount of primary hydroxyl and secondary hydroxyl), the hydroxyl value is 33mgKOH / g, and the average functionality is 3;

[0067] Polyether polyol A1-2: glycerol is used as the initiator, propylene oxide and ethylene oxide are used as polymerization monomers and ethylene oxide is terminated, the ethylene oxide monomer content is 75wt% of the total amount of ethylene oxide monomer and propylene oxide monomer, the primary hydroxyl content is 90wt% (based on the total amount of primary hydroxyl and secondary hydroxyl), the hydroxyl value is 34mgKOH / g, and the average functionality is 3;

[0068] Polyether polyol A1-3: trimethylolpropane is used as the initiator, propylene oxide and ethylene oxide are used as polymerization monomers and ethylene oxide is terminated, the ethylene oxide monomer content is 80wt% of the total amount of ethylene oxide monomer and propylene oxide monomer, the primary hydroxyl content is 85wt% (based on the total amount of primary hydroxyl and secondary hydroxyl), the hydroxyl value is 28mgKOH / g, and the average functionality is 3;

[0069] Polyether polyol A2-1: glycerol is used as the initiator, propylene oxide and ethylene oxide are used as polymerization monomers and ethylene oxide is terminated, the ethylene oxide monomer content is 25wt% of the total amount of ethylene oxide monomer and propylene oxide monomer, the primary hydroxyl content is 85wt% (based on the total amount of primary hydroxyl and secondary hydroxyl), the hydroxyl value is 26mgKOH / g, and the average functionality is 3;

[0070] Polyether polyol A2-2: glycerol is used as the initiator, propylene oxide and ethylene oxide are used as polymerization monomers and ethylene oxide is terminated, the ethylene oxide monomer content is 30wt% of the total amount of ethylene oxide monomer and propylene oxide monomer, the primary hydroxyl content is 88wt% (based on the total amount of primary hydroxyl and secondary hydroxyl), the hydroxyl value is 30mgKOH / g, and the average functionality is 3;

[0071] Polyether polyol A2-3: trimethylolpropane is used as the initiator, propylene oxide and ethylene oxide are the polymerization monomers and the ethylene oxide is terminated, the ethylene oxide monomer content is 40% of the total amount of ethylene oxide monomer and propylene oxide monomer, the primary hydroxyl content is 88wt% (based on the total amount of primary hydroxyl and secondary hydroxyl), the hydroxyl value is 33mgKOH / g, and the average functionality is 3;

[0072] Catalyst 1: Huntsman, dimethylaminopropylamine;

[0073] Catalyst 2: Huntsman, bis(3-dimethylaminopropyl)aminoisopropanol;

[0074] Catalyst 3: Huntsman, N,N-dimethyl-N,N-bis(2-hydroxypropyl)-1,3-propylenediamine;

[0075] Catalyst 4: Huntsman, N,N,N'-trimethyl-N'-hydroxyethyl bisaminoethyl ether;

[0076] Surfactant 1: Evonik B8734LF2;

[0077] Surfactant 2: Dow Chemical HR-8870;

[0078] Isocyanate B1: a mixture of polyphenylmethane polyisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate and polyol-modified isocyanate prepolymer, NCO content 30 wt%, commercially available, Wanhua WANNATE 8038.

[0079] Isocyanate B2: a mixture of polyphenylmethane polyisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate and polyol-modified isocyanate prepolymer, NCO content 26 wt %, commercially available, Wanhua WANNATE 8019.

[0080] Isocyanate B3: a mixture of polyphenylmethane polyisocyanate, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate, NCO content 32 wt %, commercially available, Wanhua WANNATE 8122 and the like.

[0081] Combined polyether (viscoelastic polyurethane foam): WANEFLEX 626 system, and WANEFLEX 621E system, commercially available, Wanhua.

[0082] Description of the test method:

[0083] Density test of polyurethane foam: The test standard adopted is ISO 845-2006;

[0084] Tensile strength test, elongation at break test: The test standard adopted is ISO 1798-2008;

[0085] Tear strength test: The test standard adopted is ISO 8067-2018;

[0086] Young's modulus and loss factor test: Use a dynamic Young's modulus and loss factor tester and test according to Z-Nr 1933 613.3 standard.

[0087] Examples 1-6

[0088] The preparation steps of Examples 1-6 are as follows:

[0089] The raw materials and amounts used in Examples 1-6 are shown in Table 1.

[0090] The raw materials of the measured A component are uniformly mixed at 25° C., and then fully mixed with the measured B component at 25° C., and then the mixed material is injected into a mold at a temperature of 65° C. for reaction foaming. The aging time of each embodiment (i.e., the time of the foaming reaction in the mold) is shown in Table 1. After the foaming is completed, the mold is opened and the foam is taken out to obtain a polyurethane foam.

[0091] The amounts of the raw materials in Table 1 are calculated in parts by mass.

[0092] Table 1 Example raw material ratio and test results

[0093]

[0094] Table 2 Comparative Example Raw Material Ratio and Test Results

[0095]

[0096] Note: Polyether polyol WANNOL F3140, EO content 80wt% (based on the total amount of EO and PO), primary hydroxyl content 50wt% (based on the total amount of primary hydroxyl and secondary hydroxyl), hydroxyl value 42mgKOH / g; polyether polyol WANNOL F3135, EO content 16wt% (based on the total amount of EO and PO), primary hydroxyl content 87wt% (based on the total amount of primary hydroxyl and secondary hydroxyl), hydroxyl value 35mgKOH / g.

[0097] According to the results of the above embodiments and comparative examples, the viscoelastic polyurethane foam prepared in the embodiments of the present invention can obtain a density of 50 to 80 kg / m while taking into account fast maturation (maturing time within 100 s, or even within 80 s). 3 , tensile strength ≥90 kPa, elongation at break ≥90%, tear strength ≥1.7 N / cm, and loss factor of 0.25-0.7, a viscoelastic polyurethane foam with good comprehensive performance. The foam material is particularly suitable for the production of automotive sound insulation pad parts. In the comparative example, it is impossible to achieve a balance between high aging efficiency and good comprehensive performance. In the better embodiments 1-6, the amount of polyether polyol A1 is 30-60 parts by mass, the amount of polyether polyol A2 is 40-65 parts by mass, and the amount of foaming agent is 3.5-5.5 parts by mass. The preparation of viscoelastic polyurethane foam not only has a higher aging efficiency, but also can take into account better comprehensive performance of viscoelastic polyurethane foam, and can obtain a density of 50-80 kg / m 3 , foam materials with tensile strength ≥100 kPa, elongation at break ≥100%, tear strength ≥1.8 N / cm, and loss factor of 0.3 to 0.7.

[0098] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A method for preparing a viscoelastic polyurethane foam, characterized in that: The viscoelastic polyurethane foam is obtained by reacting a material including an isocyanate-reactive component and an isocyanate; wherein the isocyanate-reactive component includes a polyether polyol composition, a catalyst, a surfactant and a blowing agent; The polyether polyol composition comprises polyether polyol A1 and polyether polyol A2; The hydroxyl values ​​of the polyether polyol A1 and the polyether polyol A2 are both 24-42 mgKOH / g, and based on the total amount of primary hydroxyl groups and secondary hydroxyl groups, the content of primary hydroxyl groups is ≥80 wt%; The polyether polyol A1 has an average functionality of 3-4 and is a polyether polyol using propylene oxide and ethylene oxide as polymerization monomers and capped with ethylene oxide. Based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomers is 50-90wt%; The polyether polyol A2 has an average functionality of 3-4 and is a polyether polyol using propylene oxide and ethylene oxide as polymerization monomers and capped with ethylene oxide. Based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomers is 20-40wt%; In the isocyanate reactive component, the amount of the polyether polyol A1 is 25 to 65 parts by mass, the amount of the polyether polyol A2 is 30 to 70 parts by mass, the amount of the foaming agent is 3 to 6 parts by mass, the amount of the catalyst is 0.1 to 1.5 parts by mass, and the amount of the surfactant is 0.2 to 1.5 parts by mass; The mass ratio of the isocyanate reactive component to the isocyanate is 100:30-70; the NCO content of the isocyanate is 24-32wt%.

2. The method for preparing the viscoelastic polyurethane foam according to claim 1, characterized in that: The polyether polyol A1 has a hydroxyl value of 28-42 mgKOH / g; based on the total amount of ethylene oxide and propylene oxide monomers, the proportion of ethylene oxide monomers is 70-90wt%; based on the total amount of primary hydroxyl groups and secondary hydroxyl groups, the content of primary hydroxyl groups is ≥85wt%; The polyether polyol A2 has a hydroxyl value of 24-35 mgKOH / g, and based on the total amount of primary hydroxyl groups and secondary hydroxyl groups, the content of primary hydroxyl groups is ≥85 wt %.

3. The method for preparing the viscoelastic polyurethane foam according to claim 1, characterized in that: The polyether polyol A1 uses one or more of an alcohol compound with a functionality of 3 and an alcohol compound with a functionality of 4 as an initiator; And / or, the polyether polyol A2 uses one or more of an alcohol compound with a functionality of 3 and an alcohol compound with a functionality of 4 as an initiator.

4. The method for preparing the viscoelastic polyurethane foam according to claim 3, characterized in that: The initiator of the polyether polyol A1 is one or more of glycerol, trimethylolpropane or tetrapentanol; And / or, the initiator of the polyether polyol A2 is one or more of glycerol, trimethylolpropane or tetrapentanol.

5. The method for preparing the viscoelastic polyurethane foam according to any one of claims 1 to 4, characterized in that: In the isocyanate reactive component, the amount of polyether polyol A1 is 30-60 parts by mass, the amount of polyether polyol A2 is 40-65 parts by mass, and the amount of the foaming agent is 3.5-5.5 parts by mass.

6. The method for preparing the viscoelastic polyurethane foam according to any one of claims 1 to 4, characterized in that: The isocyanate is selected from one or more of polyphenylmethane polyisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate and polyol-modified isocyanate prepolymer; And / or, the foaming agent is selected from one or more of water, CO2, alkane foaming agent, chlorine-containing foaming agent, and fluorine-containing foaming agent; And / or, the catalyst is selected from one or more of an amine catalyst and an organic metal catalyst.

7. The method for preparing the viscoelastic polyurethane foam according to any one of claims 1 to 4, characterized in that: The preparation steps of the viscoelastic polyurethane foam include: uniformly mixing the raw materials of the isocyanate reactive component to obtain a first mixed material, mixing the first mixed material with the isocyanate to obtain a second mixed material, and transferring the second mixed material to a mold for a foaming reaction; The first mixed material and the isocyanate are mixed at 20-40° C.; The foaming reaction time is 60-100s; The temperature of the mold is 50-80°C.

8. A viscoelastic polyurethane foam prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the viscoelastic polyurethane foam according to claim 8 in the preparation of automotive parts, wherein the automotive parts include automotive sound insulation pads; Alternatively, the automobile parts include one or more of an automobile carpet, a front wall, a wheel cover, a coat rack and a spare tire mat.

Images