Polyurethane foam and preparation method thereof

Abstract

The invention relates to polyurethane foam and a preparation method thereof. The preparation method of the polyurethane foam comprises the following steps: adding 50-90wt% of polymer polyol, 0.1-6wt% of a catalyst, 5-15wt% of a foaming agent and 1-10wt% of a foam stabilizer into a reaction container, mixing, and uniformly stirring for 5-30 minutes at the speed of 450 r / min by using a mechanical stirrer; adding a flame retardant with the mass fraction of 0.1-6%, and stirring to obtain a component A; the component B is added into the reaction container, the component B is an isocyanate black material, uniform mixing of the component A and the component B is achieved, foam curing is conducted for 24-48 hours, and the needed polyurethane foam is obtained. The prepared polyurethane foam has high strength, good elasticity and a stable structure, and the flame retardant property of the polyurethane foam is remarkably improved.

Description

Technical Field

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

[0002] Polyurethane foam is obtained by mixing white material and black material evenly and then foaming and aging. The white material refers to a composition composed of a combination of polyols, catalysts and foaming agents, and the main component of the black material is isocyanate. The oxygen index of ordinary polyurethane foam is only about 17 without adding flame retardants. It is very easy to burn under normal circumstances. With the gradual expansion of the application of polyurethane foam, more and more stringent requirements are put forward for the strength and flame retardancy of polyurethane foam.

[0003] At present, most of the polyurethane insulation materials on the market improve the flame retardancy of the foam by adding flame retardants such as DMMP and TCCP. However, the addition of flame retardants will cause the foam to shrink, and the use of flame retardants such as DMMP and TCCP alone can only achieve a maximum flame retardancy of Class D in GB8624-2006, which cannot meet the demand for high flame retardancy.

[0004] For example, a Chinese patent document (publication number: CN1708525A) discloses that a melamine-based flame retardant, a phosphorus-containing flame retardant and a polyether polyol are blended and fully stirred and mixed with other foaming agents, catalysts and curing agents to prepare a flame-retardant polyurethane foam material, but the flame-retardant properties will gradually be lost after long-term storage.

[0005] In addition, some relevant technicians have introduced compound compositions into polyurethane foams. For example, a Chinese patent document (publication number: CN104892889A) discloses: a compound composition of an organic phosphorus flame retardant and an inorganic flame retardant introduced into a rigid polyurethane foam. Although it can reduce the smoke release rate and improve the flame retardant properties of the material, the added mass of the flame retardant is as high as 25~45wt%, which greatly increases the bulk density of the organic foam material, reduces the uniformity and strength of the foam structure of the material, and reduces its service life.

[0006] The Chinese invention patent application (application number: CN201310510121.6) discloses: a flame retardant and heat-resistant polyurethane foam material, and discloses a method of introducing a physical flame retardant, attapulgite, to improve the flame retardant properties of polyurethane foam. Since the flame retardant used is mainly inorganic material, it affects the uniformity of polyurethane foaming, increases the brittleness of polyurethane foam, and makes it easy to pulverize.

[0007] Polyurethane foam is a material widely used in the construction, furniture, automobile, textile and other industries. It has excellent heat insulation, sound insulation, cushioning and shock absorption properties. The traditional polyurethane foam preparation method usually uses polyols and isocyanates to react to produce polyurethane. Due to its simple process and low cost, it is widely used in industrial production. However, traditional polyurethane foam has deficiencies in flame retardancy, mechanical properties and environmental friendliness, and it is difficult to meet the diverse requirements of modern industry for material properties.

[0008] Therefore, it is necessary to improve the existing technology. Summary of the invention

[0009] In the prior art, traditional polyurethane foams have deficiencies in flame retardancy, mechanical properties and environmental friendliness, and are difficult to meet the diverse demands of modern industry for material properties. Therefore, the present invention provides a polyurethane foam and a preparation method thereof for solving the above problems.

[0010] To achieve the above object, in a first aspect, the present invention provides a method for preparing a polyurethane foam, which comprises the following specific steps: S1. Add the following raw materials in different weight fractions into a reaction vessel and mix: 50-90 wt% polymer polyol, 0.1-6 wt% catalyst, 5-15 wt% foaming agent and 1-10 wt% foam stabilizer, and stir at 450 rpm for 5-30 minutes with a mechanical stirrer to mix evenly; S2, adding 0.1% to 6% by mass of a flame retardant, and stirring with a mechanical stirrer at 450 rpm for 10 to 30 minutes to obtain component A; S3, adding component B into the reaction container according to the selected mass ratio, wherein component B is isocyanate black material, stirring at 300-2000 rpm for 10-40 seconds to achieve uniform mixing of component A and component B, pouring into an acrylic mold to obtain foam, and pressing and sealing the acrylic mold to mature the foam for 24-48 hours to obtain the desired polyurethane foam; Wherein, the mass ratio of component A to component B is 1:(0.5-1) or 1:(1.6~1.8).

[0011] In one implementation, in S1, the polymer polyol includes any one or more of polyether polyol, vegetable oil polyol and polyester polyol, and the polymer polyol has a hydroxyl value of 160 mgKOH / g to 800 mgKOH / g and a functionality of 2 to 8.

[0012] In one implementation, in S1, the catalyst includes any one or more of triethylenediamine, N,N-dimethylcyclohexylamine, pentamethyldiethylenetriamine, isopropanolamine, Dabco 33-LV catalyst, Dabco BL-22 catalyst, Babco CS-90 catalyst, Polycat 5 catalyst, Polycat 8 catalyst, Jeffcat ZF-10 catalyst, and Jeffcat DMP catalyst.

[0013] In one implementation, in S2, the flame retardant includes a modified inorganic flame retardant and / or an organic phosphide. The modified inorganic flame retardant includes any one or more of modified vitrified microspheres, modified glass fibers, and modified hollow microspheres.

[0014] In one implementation, in S2, the flame retardant is a compound composition of an organic phosphide and a modified inorganic flame retardant, and the mass ratio of the two is 1:(0.5 - 2). Any one of a modifier silane coupling agent, stearic acid, or oleic acid is used to modify the inorganic flame retardant. Among them, the inorganic flame retardant includes any one of chopped glass fibers, vitrified microspheres, and silica hollow microspheres. The mass fraction of the silane coupling agent, stearic acid, or oleic acid in the modified flame retardant is 0.5 - 1.0 wt%.

[0015] In one implementation, in S2, the preparation method of the modified inorganic flame retardant is as follows: Mix deionized water and absolute ethanol in a mass ratio of 1:10 to obtain an ethanol aqueous solution. Adjust the pH value of the ethanol aqueous solution to 4 - 6, and drop the modifier at 40 - 80 °C. After mixing evenly, heat for 3 - 6 hours to obtain a hydrolysis solution; add the inorganic flame retardant to the above hydrolysis solution and mix evenly at room temperature for 25 - 30 hours, then perform centrifugal separation, drying, and sieving through an 80 - 200 mesh sieve to obtain the modified inorganic flame retardant.

[0016] In one implementation, in S2, the chopped glass fibers have a diameter of 0.08 - 0.1 mm and a length of 6 - 8 mm, and its chemical composition (w) is: SiO 2 64.4%, Al 2 O 3 14.8%, CaO 6.3%, B 2 O 3 5.2%, MgO 4.5%, and Na 2 O 3.8%.

[0017] In one implementation, in S3, the isocyanate black material includes any one or more of xylene diisocyanate, PM200, 44V20, M20S, polymethylene polyphenyl polyisocyanate, or carbodiimide-modified isocyanate.

[0018] In one implementation, in S1, the blowing agent includes any one or more of HCFC-1416 (i.e., ethylene dichloride), CFC-11, cyclopentane, n-pentane, isopentane, water (i.e., chemical blowing agent), methyl formate, HFC-245fa, and HFC-365mfc; the foam stabilizer includes any one or more of dimethyl silicone oil, phenylmethyl silicone oil, polydimethyl silicone oil, diethyl silicone oil, polydiethyl silicone oil, and methylvinyl silicone oil.

[0019] In a second aspect, the present invention further provides a polyurethane foam, which is prepared by any of the above-mentioned methods for preparing the polyurethane foam.

[0020] Beneficial effects: The present invention precisely controls the proportions and mixing conditions of polymer polyols, catalysts, foaming agents and foam stabilizers to prepare polyurethane foams with high strength, good elasticity and stable structure; the introduction of modified inorganic flame retardants and organic phosphides as flame retardants significantly improves the flame retardant properties of polyurethane foams, which can effectively prevent flame propagation under high temperature conditions and increase safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a flow chart of the steps of the method for preparing polyurethane foam provided by the present invention; Figure 2 is a scanning electron micrograph (SEM) of the polyurethane foam prepared in Example 1; Figure 3 XRD patterns of the polyurethane foams prepared in Examples 1 to 3 and Comparative Examples 1 to 2; Figure 4 It is a compression stress-compression strain curve diagram of the polyurethane foam prepared in Examples 1-4 and Comparative Examples 1-2.

[0022] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the description of the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" described below means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms is not necessarily for the same embodiment or example. Moreover, the technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0024] See also Figure 1 , Figure 1 The present invention provides a method for preparing polyurethane foam, which comprises the following specific steps: S1. Add the following raw materials in different weight fractions into a reaction vessel and mix: 50-90 wt% polymer polyol, 0.1-6 wt% catalyst, 5-15 wt% foaming agent and 1-10 wt% foam stabilizer, and stir at 450 rpm for 5-30 minutes with a mechanical stirrer to mix evenly; S2, adding 0.1-6% by mass of a flame retardant, and stirring with a mechanical stirrer at 450 rpm for 10-30 minutes to obtain component A; S3, adding component B into the reaction container according to the selected mass ratio, wherein component B is isocyanate black material, stirring at 300-2000 rpm for 10-40 seconds to achieve uniform mixing of component A and component B, pouring into an acrylic mold to obtain foam, and pressing and sealing the acrylic mold to mature the foam for 24-48 hours to obtain the desired polyurethane foam; Wherein, the mass ratio of component A to component B is 1:(0.5-1) or 1:(1.6-1.8). Preferably, the mass ratio of component A to component B is 1:(0.6-1).

[0025] The present invention ensures uniform dispersion of reactants by mixing polymer polyol, catalyst, foaming agent and foam stabilizer at a certain stirring speed and time, thereby forming a uniform foam structure; after adding the flame retardant, stirring again, further enhancing the flame retardant performance of the material; finally, adding isocyanate black material, and quickly mixing under high-speed stirring to form uniform foam, thereby ensuring the uniformity and stability of the foam.

[0026] Specifically, in S1, the polymer polyol includes any one or more of polyether polyol, vegetable oil polyol and polyester polyol, and the polymer polyol has a hydroxyl value of 160 mgKOH / g to 800 mgKOH / g and a functionality of 2 to 8. Preferably, the mass fraction of the polymer polyol is 70 to 90 wt%.

[0027] Specifically, in S1, the catalyst includes any one or more of triethylenediamine, N,N-dimethylcyclohexylamine, pentamethyldiethylenetriamine, isopropanolamine, Dabco33-LV catalyst, Dabco BL-22 catalyst, Babco CS-90 catalyst, Polycat5 catalyst, Polycat8 catalyst, Jeffcat ZF-10 catalyst and Jeffcat DMP catalyst. By adding the catalyst, the reaction speed can be accelerated and the reaction efficiency can be improved. Preferably, the mass fraction of the catalyst is 2 to 5wt%.

[0028] Specifically, in S1, the blowing agent includes any one or more of HCFC-1416 (i.e., ethylene dichloride), CFC-11, cyclopentane, n-pentane, isopentane, water (i.e., chemical blowing agent), methyl formate, HFC-245fa, and HFC-365mfc. Preferably, the mass fraction of the blowing agent is 10-15wt%.

[0029] Specifically, in S1, the foam stabilizer includes any one or more of dimethyl silicone oil, phenylmethyl silicone oil, polydimethyl silicone oil, diethyl silicone oil, polydiethyl silicone oil and methyl vinyl silicone oil. The use of the foam stabilizer can significantly improve the mechanical properties and service life of the foam. By selecting different types of foaming agents and foam stabilizers, the foaming speed and pore structure of the foam can be regulated to ensure the uniformity and stability of the foam. Preferably, the mass fraction of the foam stabilizer is 1-10wt%.

[0030] Specifically, in S2, the flame retardant includes a modified inorganic flame retardant and / or an organic phosphide, and the modified inorganic flame retardant includes any one or more of modified glass microspheres, modified glass fibers, and modified hollow microspheres. Preferably, the mass fraction of the flame retardant is 2-5wt%. The use of the modified inorganic flame retardant can improve the flame retardancy of the material without significantly increasing the density and hardness of the foam.

[0031] Furthermore, the flame retardant is a composite composition of an organic phosphide and a modified inorganic flame retardant, and the mass ratio of the two is 1:(0.5~2), wherein the inorganic flame retardant is modified using any one of a modifier silane coupling agent, stearic acid or oleic acid, wherein the inorganic flame retardant includes any one of chopped glass fibers, glass microspheres and hollow silica microspheres, and the mass fraction of the silane coupling agent, stearic acid or oleic acid in the modified flame retardant is 0.5-1.0wt%.

[0032] Specifically, in S2, the preparation method of the modified inorganic flame retardant is: Deionized water and anhydrous ethanol are mixed in a mass ratio of 1:10 to obtain an ethanol aqueous solution, the pH value of the ethanol aqueous solution is adjusted to 4-6, a modifier is added dropwise at 40-80° C., mixed evenly, and heated for 3-6 hours to obtain a hydrolysis solution; the inorganic flame retardant is added to the hydrolysis solution and evenly mixed at room temperature for 25-30 hours, centrifuged, dried, and sieved through an 80-200 mesh sieve to obtain a modified inorganic flame retardant.

[0033] The diameter of the chopped glass fiber is 0.08-0.1 mm, the length is 6-8 mm, and the chemical composition (w) is: SiO 2 64.4%,Al 2 O 3 14.8%, CaO 6.3%, B 2 O 3 5.2%, MgO 4.5% and Na 2 O 3.8%. The use of the chopped glass fibers can significantly improve the mechanical properties of the foam and enhance its tensile strength and compressive strength. The size of the hollow silica microspheres is uniformly distributed in the range of 10 to 30 μm, with a specific surface area of ​​20 to 250 m 2 / g.

[0034] Specifically, in S3, the isocyanate black material includes any one or more of xylene diisocyanate, PM200, 44V20, M20S, multiple toluene polyphenyl polyisocyanate or carbodiimide modified isocyanate.

[0035] The present invention also provides multiple embodiments to explain the technical solution of the present invention in detail.

[0036] The preparation method of the polyurethane foam of Examples 1 to 4 and Comparative Examples 1 to 2 comprises the following steps: Add component A (i.e., white material, including polymer polyol, catalyst, flame retardant, foaming agent and foam stabilizer) into the reaction container and stir at 450 rpm for 30 minutes to mix evenly; Component B (i.e., black material, which is at least one of xylene diisocyanate, PM200, 44V20, M20S, multiple toluene polyphenyl polyisocyanate or carbodiimide modified isocyanate) is added into a reaction container according to the mass ratio, and after stirring at 450 rpm for 30 seconds, the foam slurry composition is injected into an acrylic mold with a tile at the bottom, and the acrylic mold is pressed and sealed to mature the foam for 36 hours to obtain the polyurethane foam.

[0037] The proportions of various raw materials in component A and component B are shown in Table 1.

[0038] Table 1, components and their proportions in Examples 1 to 4 and Comparative Examples 1 to 2 In Table 1, “ / ” means that the item is not available or is 0.

[0039] Performance Testing: The performance of the polyurethane foam products prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were tested respectively. The test methods were based on national standards, including bulk density, compression strength, flame retardancy, dimensional stability and other properties. The specific test methods and performance data are as follows: The volume density is tested according to GB / T6343-2009; the compression strength is tested according to GB / T8813-2020; the flame retardancy is tested according to GB / T2406.2-2009; the dimensional stability is tested according to GB / T8811-2008 for the volume change rate of polyurethane foam, where the experimental conditions are set to 85°C and 85% humidity for 1000 hours. The performance tests are shown in Table 2.

[0040] Table 2, product performance test data of Examples 1 to 4 and Comparative Examples 2 According to Table 1, Table 2 and Figure 2~Figure 4 The test results, among which, Figure 2 is a scanning electron micrograph (SEM) of the polyurethane foam prepared in Example 1, Figure 3 The XRD patterns of the polyurethane foams prepared in Examples 1 to 3 and Comparative Examples 1 to 2 are as follows: Figure 4 The above results show that the polyurethane foam prepared by the present invention has excellent mechanical properties and flame retardant properties. The density of the polyurethane foam in Examples 1 to 4 is 85.7-97.6 Kg / m 3 , compression strength>0.45MPa, which is significantly better than the mechanical properties of the material prepared in the comparative example.

[0041] Specifically, the oxygen index of the polyurethane foam in Examples 1 to 4 can reach more than 30%, and has excellent flame retardant properties. At the same time, after being placed in an environment of temperature 85°C and humidity 85% for 1000 hours, the volume change rate is less than 0.15%, indicating that the sample can still maintain good dimensional stability after long-term use in a high temperature and high humidity environment, can be used in a high temperature environment, has high thermal stability, and can meet the use requirements of building thermal insulation refractory materials and integrated bathroom thermal insulation materials.

[0042] The flame retardant in the present invention adopts a composite composition of an organic phosphorus flame retardant and a modified inorganic flame retardant, which can exert the synergistic effect of the flame retardant element phosphorus group and the nano-modified inorganic flame retardant, improve the high flame retardant properties and mechanical properties of the prepared polyurethane foam, and the oxygen index can reach 28-32%. It has broad application prospects in the technical fields of building thermal insulation refractory materials and integrated bathroom thermal insulation materials.

[0043] Among them, the modified short glass fiber is introduced, so that the short glass fiber with reinforcing properties has good mixing uniformity with the polyurethane foam, and is compounded with the polyurethane to improve the cohesive energy of the material and achieve the effect of strengthening and toughening. The prepared polyurethane foam has the characteristics of light weight and high strength, the vertical compression strength is between 450~600kPa, and the apparent volume density is between 65~100kg / m 3 The polymer polyol used has high functionality, which significantly improves the cross-linking degree of the rigid polyurethane foam, thereby improving the heat resistance and flame retardancy of the rigid polyurethane foam.

[0044] In the present invention, the inorganic flame retardant is modified by adopting a chemical surface modification strategy to achieve uniform mixing of the flame retardant and other components of the foam slurry, significantly improve the uniformity of the polyurethane foam, and avoid the embrittlement and powdering of the polyurethane foam material. Therefore, a light and high-strength polyurethane foam is obtained, and the oxygen index of the material is improved while retaining high mechanical properties.

[0045] In summary, the present invention precisely controls the ratio and mixing conditions of polymer polyol, catalyst, foaming agent and foam stabilizer to prepare a polyurethane foam with high strength, good elasticity and stable structure; introduces modified inorganic flame retardant and organic phosphide as flame retardants, which significantly improves the flame retardant properties of polyurethane foam, enables it to effectively prevent flame propagation under high temperature conditions, and increases safety.

[0046] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing polyurethane foam, characterized in that: The specific steps include: S1. Add the following raw materials in different weight fractions into a reaction vessel and mix: 50-90 wt% polymer polyol, 0.1-6 wt% catalyst, 5-15 wt% foaming agent and 1-10 wt% foam stabilizer, and stir at 450 rpm for 5-30 minutes with a mechanical stirrer to mix evenly; S2, adding 0.1% to 6% by mass of a flame retardant, and stirring with a mechanical stirrer at 450 rpm for 10 to 30 minutes to obtain component A; S3, adding component B into the reaction container according to the selected mass ratio, wherein component B is isocyanate black material, stirring at 300-2000 rpm for 10-40 seconds to achieve uniform mixing of component A and component B, pouring into an acrylic mold to obtain foam, and pressing and sealing the acrylic mold to mature the foam for 24-48 hours to obtain the desired polyurethane foam; Wherein, the mass ratio of component A to component B is 1:(0.5-1) or 1:(1.6~1.8).

2. The method for preparing polyurethane foam according to claim 1, characterized in that: In S1, the polymer polyol includes any one or more of polyether polyol, vegetable oil polyol and polyester polyol, and the polymer polyol has a hydroxyl value of 160 mgKOH / g to 800 mgKOH / g and a functionality of 2 to 8.

3. The method for preparing polyurethane foam according to claim 1, characterized in that: In S1, the catalyst includes any one or more of triethylenediamine, N,N-dimethylcyclohexylamine, pentamethyldiethylenetriamine, isopropanolamine, Dabco33-LV catalyst, Dabco BL-22 catalyst, Babco CS-90 catalyst, Polycat5 catalyst, Polycat8 catalyst, Jeffcat ZF-10 catalyst and Jeffcat DMP catalyst.

4. The method for preparing polyurethane foam according to claim 1, characterized in that: In S2, the flame retardant includes a modified inorganic flame retardant and / or an organic phosphide, and the modified inorganic flame retardant includes any one or more of modified glass microspheres, modified glass fibers, and modified hollow microspheres.

5. The method for preparing polyurethane foam according to claim 4, characterized in that: In S2, the flame retardant is a composite composition of an organic phosphide and a modified inorganic flame retardant, and the mass ratio of the two is 1:(0.5~2), wherein the inorganic flame retardant is modified using any one of the modifiers silane coupling agent, stearic acid or oleic acid, wherein the inorganic flame retardant includes any one of chopped glass fibers, glass microspheres and hollow silica microspheres, and the mass fraction of the silane coupling agent, stearic acid or oleic acid in the modified flame retardant is 0.5-1.0wt%.

6. The method for preparing polyurethane foam according to claim 5, characterized in that: In S2, the preparation method of the modified inorganic flame retardant is: Deionized water and anhydrous ethanol are mixed in a mass ratio of 1:10 to obtain an ethanol aqueous solution, the pH value of the ethanol aqueous solution is adjusted to 4-6, a modifier is added dropwise at 40-80° C., the mixture is evenly mixed and heated for 3-6 hours to obtain a hydrolysis solution; The inorganic flame retardant is added into the hydrolysis solution and uniformly mixed at room temperature for 25-30 hours, centrifuged, dried and passed through a 80-200 mesh sieve to obtain a modified inorganic flame retardant.

7. The method for preparing polyurethane foam according to claim 5, characterized in that: In S2, the diameter of the chopped glass fiber is 0.08-0.1 mm, the length is 6-8 mm, and the chemical composition (w) is: SiO2 64.4%, Al2O3 14.8%, CaO6.3%, B2O3 5.2%, MgO 4.5% and Na2O 3.8%.

8. The method for preparing polyurethane foam according to claim 1, characterized in that: In S3, the isocyanate black material includes any one or more of xylene diisocyanate, PM200, 44V20, M20S, multiple toluene polyphenyl polyisocyanate or carbodiimide modified isocyanate.

9. The method for preparing polyurethane foam according to claim 1, characterized in that: In S1, the foaming agent includes any one or more of HCFC-1416 (i.e., ethylene dichloride), CFC-11, cyclopentane, n-pentane, isopentane, water (i.e., chemical foaming agent), methyl formate, HFC-245fa, and HFC-365mfc; the foam stabilizer includes any one or more of dimethyl silicone oil, phenylmethyl silicone oil, polydimethyl silicone oil, diethyl silicone oil, polydiethyl silicone oil, and methylvinyl silicone oil.

10. A polyurethane foam, characterized in that: The polyurethane foam is prepared by the method for preparing the polyurethane foam according to any one of claims 1 to 9.

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