Tung oil-based non-isocyanate polyurethane flexible foam and preparation method thereof

Abstract

The invention relates to tung oil-based non-isocyanate polyurethane flexible foam and a preparation method thereof, and belongs to the technical field of polyurethane materials, and the tung oil-based non-isocyanate polyurethane flexible foam comprises the following components: tung oil-based cyclic carbonate, tung oil-based epoxy resin, diethylenetriamine, hexamethylenediamine, potassium hydroxide, microcrystalline cellulose and water. The preparation method comprises the following specific preparation steps: preheating tung oil-based cyclic carbonate and tung oil-based epoxy resin, and mixing to obtain a resin mixture; and mixing and fully stirring the resin mixture, the mixed curing agent, a potassium hydroxide aqueous solution and nano cellulose, and quickly putting the mixture into a drying oven at 80-110 DEG C for foaming and curing for 3-5 hours to obtain the tung oil-based non-isocyanate polyurethane flexible foam. The tung oil is used as the main raw material, the water is used as the foaming agent, the nano cellulose is used as the filler, the bio-based content of the foam is increased, and compared with an isocyanate route, the production cost is reduced, the preparation process is green and environment-friendly, and the application prospect is better.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane material preparation, and particularly relates to a tung oil-based non-isocyanate polyurethane soft foam and a preparation method thereof. Background Art

[0002] As a mature polymer material, polyurethane has broad market prospects in foams, plastics, elastomers, etc. Among them, polyurethane soft foam is widely used in sound insulation materials, thermal insulation materials, decorative materials, etc. due to its good resilience, sound absorption, and breathability. However, the isocyanate that must be used in the production process of traditional polyurethane is highly toxic and can cause serious harm to the human body. At the same time, the moisture sensitivity of isocyanate is not conducive to storage and transportation, which also limits its further development. To solve this problem, the preparation scheme of non-isocyanate polyurethane (NIPU) came into being.

[0003] The synthesis of NIPU is mainly through the polymerization of polycyclic carbonates and polyamines, but this route still relies on petroleum-based derivatives. Therefore, with the implementation of sustainable development and environmental protection policies, the development of synthetic routes using biomass materials as raw materials has become an extremely important issue in the development of the polyurethane industry. Vegetable oils and fats are considered to be chemical raw materials with great potential due to their renewable and easy accessibility. Introducing vegetable oils and fats into the production route of polyurethane can not only reduce dependence on petroleum-based raw materials, but also increase the added value of oils and fats. In addition, the current NIPU self-foaming process is mainly induced by mercaptan, which causes the foam to have a strong smell, limiting its application areas. In order to avoid the above defects, this project selected tung oil as the raw material to prepare tung oil-based non-isocyanate polyurethane soft foam, and developed a preparation route for water-induced self-foaming NIPU foam. Summary of the invention

[0004] Technical problem to be solved: In order to solve the problems of high toxicity, high petroleum dependence and heavy odor of mercaptan-induced foaming in the preparation process of polyurethane, the present invention provides a tung oil-based non-isocyanate polyurethane foam and a preparation method.

[0005] Technical solution: A method for preparing a tung oil-based non-isocyanate polyurethane soft foam, comprising the following steps: (1) Synthesis of tung oil-based epoxy resin: mixing tung oil acid and maleic anhydride, wherein the molar ratio of tung oil acid to maleic anhydride is 1:(0.3-2), reacting at 100-150°C for 1-5h to obtain tung oil acid maleic anhydride; dissolving tung oil acid maleic anhydride in a solvent and reacting with 10%-80% NaOH aqueous solution is used for ring opening, and hydrochloric acid is used for acidification until the pH value of the system is 2-3 to obtain tung oil triacid; tung oil triacid, epichlorohydrin and catalyst 1 are mixed, wherein the molar ratio of carboxyl group to epoxy group is 1:(6-12), the amount of catalyst 1 is 1wt.%-5wt.% of tung oil triacid, and it is at least one of benzyltriethylammonium chloride, benzyltriethylammonium bromide, benzyltriethylammonium iodide and tetrabutylammonium chloride, and the reaction is carried out at 100-120°C for 3-5h, and then catalyst 2 is added and reacted at 50-70°C for 2-4h to prepare tung oil-based epoxy resin, and catalyst 2 is added and reacted at 50-70°C for 2-4h to obtain tung oil-based epoxy resin. The amount of catalyst 2 is 10wt.% to 30wt.% of tung oil triacid, which is at least one of sodium hydroxide, potassium hydroxide, triethylamine and tetraethylamine; (2) Synthesis of tung oil-based cyclic carbonate: tung oil-based epoxy resin, CO2, catalyst 3 and catalyst 4 are added to a high-pressure reactor, the amount of catalyst 3 is 5wt.% to 15wt.% of tung oil-based epoxy resin, which is at least one of tetrabutylammonium iodide, tetrabutylammonium bromide and tetrabutylammonium iodide; the amount of catalyst 4 is 1wt.% to 5wt.% of tung oil triacid, which is L-ascorbic acid, sodium L-ascorbate and sodium citrate. at least one of the following: reacting at 60 to 100° C. and 0.35 to 3.5 MPa for 6 to 48 hours to synthesize tung oil-based cyclic carbonate; (3) preheating the tung oil-based cyclic carbonate and tung oil-based epoxy resin and mixing them to obtain a resin mixture, wherein the molar ratio of the cyclic carbonate group to the epoxy group of the tung oil-based cyclic carbonate and the tung oil-based epoxy resin is 1:(0.25 to 1); (4) mixing the resin mixture, a mixed curing agent, an aqueous potassium hydroxide solution and nanocellulose and stirring them thoroughly, wherein the molar ratio of potassium hydroxide to water in the aqueous potassium hydroxide solution is 1:(0.1 to 0.5), and the molar ratio of water to cyclic carbonate is 1:(0.25 to 1). The molar ratio of the ester group is 1:(0.2-0.7), and the mixture is placed in an oven at 80-110°C for foaming and curing for 3-5 hours to obtain a tung oil-based non-isocyanate polyurethane soft foam; the mixed curing agent is hexamethylenediamine and one of tri(2-aminoethyl)amine, diethylenetriamine, triethylenetetramine and pentaethylenehexamine, which are blended according to the amino molar ratio of 1:(0.43-1), the molar ratio of the total amino group to the cyclic carbonate group is 1:(1-1.75), the nanocellulose particle size is 100-500nm, and the amount used accounts for 1wt.%-20wt.% of the total amount of the reactants.

[0006] Preferably, in the above step (1), the molar ratio of eleostearic acid to maleic anhydride is 1:1.

[0007] Preferably, the solvent in the above step (1) is at least one of anhydrous ethanol, methanol and propanol.

[0008] Preferably, in the reaction of tung oil tricarboxylic acid and epichlorohydrin in the above step (1), the molar ratio of carboxyl group to epoxy group is 1:10.

[0009] Preferably, in the above step (3), the molar ratio of cyclocarbonate groups to epoxy groups of tung oil-based cyclocarbonate and tung oil-based epoxy resin is 1:0.25.

[0010] Preferably, in the above step (4), the molar ratio of potassium hydroxide to water in the potassium hydroxide aqueous solution is 1:0.5, and the molar ratio of water to cyclic carbonate groups is 1:0.25.

[0011] Preferably, the mixed curing agent in the above step (4) is obtained by blending hexamethylenediamine with one of tri(2-aminoethyl)amine, diethylenetriamine, triethylenetetramine and pentaethylenehexamine at an amino molar ratio of 1:0.43, and the molar ratio of total amino groups to cyclic carbonate groups is 1:1.75.

[0012] Beneficial effects: (1) The polyurethane foam is prepared by reacting tung oil-based cyclic carbonate with polyamine. Compared with the isocyanate route, this scheme is more environmentally friendly. (2) Tung oil is a renewable resource, cheap and easy to obtain. Using it as a raw material to prepare polyurethane foam increases the utilization value of tung oil. (3) The scheme uses tung oil-based cyclic carbonate and tung oil-based epoxy resin with ester ring structure to generate non-isocyanate polyurethane soft foam with adjustable rigidity. At the same time, water is used as a foaming agent to avoid the use of chemical foaming agents, thereby reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Infrared spectra of nanocellulose, tung oil epoxy, tung oil cyclocarbonate and NIPU.

[0014] Figure 2 2 are stress-strain diagrams of Examples 1 to 5.

[0015] Figure 3 These are stress-strain diagrams for Examples 3, 8, and 9.

[0016] Figure 4 This is a scanning electron microscope image of the object of Example 1.

[0017] Figure 5 This is a scanning electron microscope image of the object of Example 2.

[0018] Figure 6 This is a scanning electron microscope image of the object of Example 3.

[0019] Figure 7 This is a scanning electron microscope image of the object of Example 4.

[0020] Figure 8 This is a scanning electron microscope image of the object of Example 5.

[0021] Fig. 9 This is a scanning electron microscope image of the actual object of Example 6.

[0022] Fig.10 This is a scanning electron microscope image of the actual object of Example 7. DETAILED DESCRIPTION

[0023] The following examples of the present invention are only used as further explanations of the present invention and cannot be used as limiting the content or scope of the present invention. The present invention is further described in detail below in conjunction with the examples.

[0024]

[0025] Example 1

[0026] Mix 34.1g of tung oil-based cyclic carbonate and 13.75g of tung oil-based epoxy resin and preheat in an oven at 90°C for 30 minutes to obtain a resin mixture, take 7.625g of hexamethylenediamine and melt it in a water bath with 2.9g of diethylenetriamine to obtain a mixed curing agent, take 1.05g of potassium hydroxide and dissolve it in 0.675g of ultrapure water to obtain a potassium hydroxide aqueous solution, first stir the resin mixture for 3 minutes, then add the mixed curing agent and the potassium hydroxide aqueous solution and quickly stir, put it in an oven at 100°C for foaming and curing for 5 hours to obtain tung oil-based non-isocyanate polyurethane soft foam 1.

[0027] Example 2

[0028] Mix 34.1g of tung oil-based cyclic carbonate and 13.75g of tung oil-based epoxy resin and preheat in an oven at 90°C for 30 minutes to obtain a resin mixture, take 7.625g of hexamethylenediamine and melt it in a water bath and add 2.9g of diethylenetriamine to obtain a mixed curing agent, take 1.05g of potassium hydroxide and dissolve it in 0.675g of ultrapure water to obtain a potassium hydroxide aqueous solution, first take 3.25g of nanocellulose and the resin mixture and stir for 3min, then add the mixed curing agent and the potassium hydroxide aqueous solution and stir quickly, put it in an oven at 100°C for foaming and curing for 5h to obtain tung oil-based non-isocyanate polyurethane soft foam 2.

[0029] Example 3

[0030] Mix 34.1g of tung oil-based cyclic carbonate and 13.75g of tung oil-based epoxy resin and preheat in an oven at 90°C for 30min to obtain a resin mixture, take 7.625g of hexamethylenediamine and melt it in a water bath and add 2.9g of diethylenetriamine to obtain a mixed curing agent, take 1.05g of potassium hydroxide and dissolve it in 0.675g of ultrapure water to obtain a potassium hydroxide aqueous solution, first take 6.65g of nanocellulose and the resin mixture and stir for 3min, then add the mixed curing agent and the potassium hydroxide aqueous solution and stir quickly, put it in an oven at 100°C for foaming and curing for 5h to obtain tung oil-based non-isocyanate polyurethane soft foam 3.

[0031] Example 4

[0032] Mix 34.1g of tung oil-based cyclic carbonate and 13.75g of tung oil-based epoxy resin and preheat in an oven at 90°C for 30 minutes to obtain a resin mixture, take 7.625g of hexamethylenediamine and melt it in a water bath and add 2.9g of diethylenetriamine to obtain a mixed curing agent, take 1.05g of potassium hydroxide and dissolve it in 0.675g of ultrapure water to obtain a potassium hydroxide aqueous solution, first take 10.55g of nanocellulose and the resin mixture and stir for 3min, then add the mixed curing agent and the potassium hydroxide aqueous solution and stir quickly, put it in an oven at 100°C for foaming and curing for 5h to obtain tung oil-based non-isocyanate polyurethane soft foam 4.

[0033] Example 5

[0034] Mix 34.1g of tung oil-based cyclic carbonate and 13.75g of tung oil-based epoxy resin and preheat in an oven at 90°C for 30 minutes to obtain a resin mixture, take 7.625g of hexamethylenediamine and melt it in a water bath and add 2.9g of diethylenetriamine to obtain a mixed curing agent, take 1.05g of potassium hydroxide and dissolve it in 0.675g of ultrapure water to obtain a potassium hydroxide aqueous solution, first take 14.95g of nanocellulose and the resin mixture and stir for 3min, then add the mixed curing agent and the potassium hydroxide aqueous solution and stir quickly, put it in an oven at 100°C for foaming and curing for 5h to obtain tung oil-based non-isocyanate polyurethane soft foam 5.

[0035] Example 6

[0036] Mix 34.1g of tung oil-based cyclic carbonate and 20.65g of tung oil-based epoxy resin and preheat in an oven at 90°C for 30 minutes to obtain a resin mixture, take 9.15g of hexamethylenediamine and melt it in a water bath and add 2.9g of diethylenetriamine to obtain a mixed curing agent, take 1.05g of potassium hydroxide and dissolve it in 0.675g of ultrapure water to obtain a potassium hydroxide aqueous solution, first take 7.6g of nanocellulose and the resin mixture and stir for 3min, then add the mixed curing agent and the potassium hydroxide aqueous solution and stir quickly, put it in an oven at 100°C for foaming and curing for 5h to obtain tung oil-based non-isocyanate polyurethane soft foam 8.

[0037] Example 7

[0038] Mix 34.1g of tung oil-based cyclic carbonate and 27.5g of tung oil-based epoxy resin and preheat in an oven at 90°C for 30 minutes to obtain a resin mixture, take 10.65g of hexamethylenediamine and melt it in a water bath and add 4.05g of diethylenetriamine to obtain a mixed curing agent, take 1.05g of potassium hydroxide and dissolve it in 0.675g of ultrapure water to obtain a potassium hydroxide aqueous solution, first take 8.6g of nanocellulose and the resin mixture and stir for 3min, then add the mixed curing agent and the potassium hydroxide aqueous solution and stir quickly, put it in an oven at 100°C for foaming and curing for 5h to obtain tung oil-based non-isocyanate polyurethane soft foam 9.

[0039] The properties of the tung oil-based non-isocyanate polyurethane soft foams prepared in Examples 1 to 7 were tested, and the specific test structure is shown in Table 1.

[0040] Table 1. Basic properties of tung oil-based non-isocyanate polyurethane soft foam

[0041] sample <![CDATA[Density (Kg·m -3 )]]> Compression modulus (MPa) Gel content (%) Cell diameter (μm) Example 1 271 0.0325±0.0613 70.9 296±13 Example 2 329 0.0502±0.0367 70.4 281±25 Example 3 342 0.4495±0.009 99.1 258±9 Example 4 362 1.1335±0.0152 80.6 210±32 Example 5 458 2.6001±0.0523 85.2 158±18 Example 6 276 0.03718±0.013 96.8 347±31 Example 7 204 0.02001±0.0352 97.2 454±7

[0042] Combined with Table 1, the cell diameter and compression modulus of different samples of tung oil-based non-isocyanate polyurethane foam prepared in Examples 1 to 7 show that as the proportion of nanocellulose filler in the formula increases, the cell diameter of the foam gradually decreases, while the compression increases; as the epoxy group in the formula increases, the cell diameter of the soft foam increases, and the compression modulus decreases. By using tung oil to prepare the raw material, the green and environmentally friendly preparation of tung oil-based non-isocyanate polyurethane foam is achieved, the cost of preparing non-isocyanate polyurethane foam is reduced, and the utilization value of tung oil is improved.

[0043] The above examples are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing tung oil-based non-isocyanate polyurethane soft foam, characterized in that: The following steps are involved: (1) Synthesis of tung oil-based epoxy resin: tung oil acid and maleic anhydride are mixed in a molar ratio of 1:(0.3-2) and reacted at 100-150°C for 1-5h to obtain tung oil acid maleic anhydride; tung oil acid maleic anhydride is dissolved in a solvent and then ring-opened with a 10%-80% NaOH aqueous solution, and acidified with hydrochloric acid until the pH value of the system is 2-3 to obtain tung oil triacid. ; Tung oil triacid, epichlorohydrin and catalyst 1 are mixed, wherein the molar ratio of carboxyl group to epoxy group is 1:(6~12), the amount of catalyst 1 is 1wt.%~5wt.% of tung oil triacid, and at least one of benzyltriethylammonium chloride, benzyltriethylammonium bromide, benzyltriethylammonium iodide and tetrabutylammonium chloride, and the mixture is reacted at 100~120℃ for 3~5h, and then catalyst 2 is added and reacted at 50~70℃ for 2~4h to prepare tung oil-based epoxy resin, wherein the amount of catalyst 2 is 10 wt.%~30 wt.% of tung oil triacid, and at least one of sodium hydroxide, potassium hydroxide, triethylamine and tetraethylamine; (2) Synthesis of tung oil-based cyclic carbonate: tung oil-based epoxy resin, CO2, catalyst 3 and catalyst 4 are added into a high-pressure reactor, and the amount of catalyst 3 is 5 wt.%~15 wt.%, which is at least one of tetrabutylammonium iodide, tetrabutylammonium bromide and tetrabutylammonium iodide; the amount of catalyst 4 is 1 wt.%~5wt.% of tung oil triacid, which is at least one of L-ascorbic acid, sodium L-ascorbate and sodium citrate; react at 60~100℃ and pressure 0.35~3.5Mpa for 6~48h to synthesize tung oil-based cyclic carbonate; (3) preheat the tung oil-based cyclic carbonate and tung oil-based epoxy resin and mix them to obtain a resin mixture, the molar ratio of cyclic carbonate group to epoxy group of the tung oil-based cyclic carbonate and the tung oil-based epoxy resin is 1:(0.25~1); (4) The resin mixture, the mixed curing agent, the potassium hydroxide aqueous solution and the nanocellulose are mixed and fully stirred, wherein the molar ratio of potassium hydroxide to water in the potassium hydroxide aqueous solution is 1:(0.1-0.5), and the molar ratio of water to cyclic carbonate groups is 1:(0.2-0.7), and the mixture is placed in an oven at 80-110°C for foaming and curing for 3-5 hours to obtain a tung oil-based non-isocyanate polyurethane soft foam; the mixed curing agent is hexamethylenediamine and one of tri(2-aminoethyl)amine, diethylenetriamine, triethylenetetramine and pentaethylenehexamine, which are blended according to an amino molar ratio of 1:(0.43-1), and the molar ratio of total amino groups to cyclic carbonate groups is 1:(1-1.75); the nanocellulose particle size is 100-500nm, and the amount used accounts for 1 wt.%-20 wt.% of the total reactants.

2. A method for preparing tung oil-based non-isocyanate polyurethane soft foam, characterized in that: In the step (1), the molar ratio of eleostearic acid to maleic anhydride is 1:

1.

3. A method for preparing tung oil-based non-isocyanate polyurethane soft foam, characterized in that: The solvent in step (1) is at least one of anhydrous ethanol, methanol and propanol.

4. A method for preparing tung oil-based non-isocyanate polyurethane soft foam, characterized in that: In the reaction of tung oil tricarboxylic acid and epichlorohydrin in step (1), the molar ratio of carboxyl group to epoxy group is 1:

10.

5. A method for preparing tung oil-based non-isocyanate polyurethane soft foam, characterized in that: In the step (3), the molar ratio of the cyclocarbonate group to the epoxy group of the tung oil-based cyclocarbonate and the tung oil-based epoxy resin is 1:0.

25.

6. A method for preparing tung oil-based non-isocyanate polyurethane soft foam, characterized in that: In the step (4), the molar ratio of potassium hydroxide to water in the potassium hydroxide aqueous solution is 1:0.5, and the molar ratio of water to cyclic carbonate groups is 1:0.

25.

7. A method for preparing tung oil-based non-isocyanate polyurethane soft foam, characterized in that: The mixed curing agent in step (4) is obtained by blending hexamethylenediamine with one of tri(2-aminoethyl)amine, diethylenetriamine, triethylenetetramine and pentaethylenehexamine at an amino molar ratio of 1:0.43, and the molar ratio of total amino groups to cyclic carbonate groups is 1:1.75.

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