High-physical-property bio-based self-crosslinking waterborne polyurethane resin and preparation method thereof

Abstract

The invention belongs to the field of synthetic leather surface layer resin, and particularly relates to high-physical-property bio-based self-crosslinking waterborne polyurethane resin and a preparation method thereof. The resin is prepared from the following raw materials: castor oil, macromolecular polyol, a hydrophilic chain extender, diisocyanate, a neutralizer and the like. According to the preparation method disclosed by the invention, dehydrated castor oil is added in synthesis, and then the waterborne polyurethane resin with a special structure is designed by utilizing the'tailorability 'of a waterborne polyurethane molecular structure. The dehydrated castor oil and macromolecular polyols such as polyether glycol and polycarbonate glycol are mixed and then are used for synthesizing the waterborne polyurethane resin. After the emulsion is dried to form a film, active methylene exists in the molecular structure of the dehydrated castor oil, and the castor oil can be subjected to oxidation reaction with oxygen in the air in a normal-temperature environment, so that the crosslinking degree of the resin is improved, and the purpose of improving the physical property of the resin is achieved. The waterborne polyurethane synthetic leather surface layer resin prepared by the invention shows high wear resistance and excellent normal and low temperature bending performance.

Description

Technical Field

[0001] The invention belongs to the field of synthetic leather surface layer resins, and specifically relates to a high-physical-property bio-based, self-crosslinking waterborne polyurethane resin and a preparation method thereof. Background Art

[0002] Waterborne polyurethane synthetic leather is the latest generation of traditional solvent-based synthetic leather. It does not contain toxic organic solvents and conforms to the requirements of sustainable development in the world. Compared with traditional solvent-based PU leather, waterborne PU leather is pollution-free during the production process, and no toxic and harmful waste gas and wastewater are discharged, which is truly harmless to the body. Waterborne polyurethane synthetic leather has the advantages of environmental protection, excellent performance, and health and harmlessness. It is widely used in clothing, shoemaking, luggage, furniture and other industries. In particular, it is used to make products that need to come into contact with water-based substances, such as shoes, clothing, gloves, etc., because it has excellent water resistance and can maintain good performance and appearance in a humid environment.

[0003] The existing waterborne polyurethane synthetic leather surface resin, in order to achieve high performance of synthetic leather, is mainly solved from two aspects: First, add trihydroxy small molecule polyols when synthesizing waterborne polyurethane to increase the crosslinking degree of the resin and thus improve the performance of the resin. Second, add a certain proportion of feel agent after the waterborne polyurethane is synthesized.

[0004] The first method has the disadvantage that the synthesis mostly adopts the acetone method, the cross-linking degree increases, the viscosity of the prepolymer increases, the amount of acetone increases, and the cost increases. The second method requires compounding of the waterborne polyurethane emulsion, which increases the operation process. In addition, the compatibility of the resin and the feel agent will have a negative impact over time.

[0005] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a high-physical-property bio-based, self-crosslinking waterborne polyurethane resin, which comprises the following preparation raw materials in parts by weight: 10 to 30 parts of dehydrated castor oil, 30 to 70 parts of macromolecular polyols, 4 to 10 parts of hydrophilic chain extenders, 30 to 70 parts of diisocyanates, 4 to 10 parts of neutralizers, and 5 to 10 parts of diamine chain extenders.

[0007] Preferably, the high-physical-property bio-based, self-crosslinking waterborne polyurethane resin comprises the following raw materials in parts by weight: 20 parts of dehydrated castor oil, 45 parts of macromolecular polyol, 6 parts of hydrophilic chain extender, 45 parts of diisocyanate, 4.5 parts of neutralizer, and 5 parts of diamine chain extender.

[0008] Preferably, the macromolecular polyol comprises polyether diol or polycarbonate diol.

[0009] Preferably, the hydrophilic chain extender comprises dimethylol propionic acid or dimethylol butyric acid.

[0010] Preferably, the diisocyanate comprises TDI, IPDI or hydrogenated MDI.

[0011] Preferably, the neutralizing agent is triethylamine.

[0012] Preferably, the diamine chain extender is ethylenediamine, isophoronediamine or hydrazine hydrate.

[0013] Based on the same technical concept, another embodiment of the present invention is to provide a method for preparing a bio-based, self-crosslinking waterborne polyurethane resin with high physical properties, the preparation method comprising the following steps:

[0014] (1) mixing dehydrated castor oil and macromolecular polyol, and performing vacuum dehydration under heating conditions to obtain an anhydrous primary mixture;

[0015] (2) sequentially adding a hydrophilic chain extender and a diisocyanate to the anhydrous primary mixture, performing a first reaction under heating conditions, then cooling the mixture and adding a neutralizing agent to perform a second reaction to obtain a prepolymer;

[0016] (3) Under stirring conditions, the prepolymer is added to deionized water, and finally a diamine chain extender aqueous solution is added dropwise, and after continuous stirring, a high-property bio-based, self-crosslinking waterborne polyurethane resin is obtained.

[0017] Preferably, in step (1), the heating temperature is 100-110° C., and the vacuum dehydration time is 1-2 h.

[0018] Preferably, in step (2), the first reaction is carried out at 80-85° C. for 2-4 h, and then the temperature is lowered to 73-75° C. for a second reaction for 0.5 h.

[0019] The beneficial effects of the present invention are:

[0020] The preparation method of the present invention adds dehydrated castor oil during the synthesis, and then uses the "tailorability" of the waterborne polyurethane molecular structure to design a waterborne polyurethane resin with a special structure. Dehydrated castor oil is mixed with macromolecular polyols such as polyether diols and polycarbonate diols and used for the synthesis of waterborne polyurethane resins. After the emulsion is dried to form a film, there are active methylene groups in the molecular structure of the dehydrated castor oil, which can react with oxygen in the air at room temperature to increase the crosslinking degree of the resin, thereby achieving the purpose of improving the physical properties of the resin. The waterborne polyurethane synthetic leather surface layer resin prepared by the present invention exhibits high wear resistance and excellent bending performance at room temperature and low temperature.

[0021] In addition, the preparation method is simple and easy to control; and the synthesis process adopts a solvent-free method or uses a small amount of environmentally friendly solvent, and the synthesized product is a green and environmentally friendly product. DETAILED DESCRIPTION

[0022] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0023] Example 1

[0024] This embodiment provides a method for preparing a bio-based, self-crosslinking waterborne polyurethane resin with high physical properties, the preparation method comprising the following steps:

[0025] (1) Accurately weigh 15 g of dehydrated castor oil and 50 g of polyether diol, add them into a four-necked round-bottom flask and start stirring, heat to 100° C. under vacuum conditions to dehydrate for 2 h, and obtain an anhydrous initial mixture;

[0026] (2) cooling to 60° C., adding 6 g of dimethylol propionic acid as a hydrophilic chain extender, mixing well, and then adding 32 g of TDI, heating to 80° C. and keeping warm, and performing a first reaction for 4 h; then cooling to 73° C., adding 4.5 g of triethylamine as a neutralizing agent, and performing a second reaction for 0.5 h to obtain a prepolymer;

[0027] (3) Weigh 250 g of deionized water and place it in a dispersion device, turn on the disperser, and slowly add the prepolymer while stirring. After the prepolymer is added, add 20 g of ethylenediamine aqueous solution (ethylenediamine: water = 2:18) dropwise, continue stirring for 4 hours, and finally filter to obtain a high-property bio-based, self-crosslinking waterborne polyurethane resin.

[0028] Example 2

[0029] This embodiment provides a method for preparing a bio-based, self-crosslinking waterborne polyurethane resin with high physical properties, the preparation method comprising the following steps:

[0030] (1) Accurately weigh 20 g of dehydrated castor oil and 45 g of polyether diol, add them into a four-necked round-bottom flask and start stirring, heat to 110° C. under vacuum conditions to dehydrate for 1 h to obtain an anhydrous initial mixture;

[0031] (2) cooling to 60° C., adding 6 g of dimethylolbutyric acid as a hydrophilic chain extender, mixing well, and then adding 45 g of IPDI, heating to 85° C. and keeping warm, and performing a first reaction for 2 h; then cooling to 75° C., adding 4.5 g of triethylamine as a neutralizing agent, and performing a second reaction for 0.5 h to obtain a prepolymer;

[0032] (3) Weigh 300 g of deionized water and place it in a dispersion device, turn on the disperser, and slowly add the prepolymer while stirring. After the prepolymer is added, add 50 g of isophorone diamine aqueous solution (isophorone diamine: water = 2:18) dropwise, continue stirring for 5 hours, and finally filter to obtain a high-property bio-based, self-crosslinking waterborne polyurethane resin.

[0033] Example 3

[0034] This embodiment provides a method for preparing a bio-based, self-crosslinking waterborne polyurethane resin with high physical properties, the preparation method comprising the following steps:

[0035] (1) Accurately weigh 18 g of dehydrated castor oil and 43 g of polycarbonate diol, add them into a four-necked round-bottom flask and start stirring, and heat to 105° C. under vacuum conditions to dehydrate for 3 h to obtain an anhydrous initial mixture;

[0036] (2) cooling to 60° C., adding 7 g of dimethylol propionic acid as a hydrophilic chain extender, mixing well, then adding 50 g of hydrogenated MDI, heating to 83° C. and keeping warm, and carrying out the first reaction for 3 h; then cooling to 73° C., adding 5 g of triethylamine as a neutralizing agent, and carrying out the second reaction for 0.5 h to obtain a prepolymer;

[0037] (3) Weigh 350 g of deionized water and place it in a dispersing device, turn on the disperser, and slowly add the prepolymer while stirring. After the prepolymer is added, add 20 g of hydrazine hydrate aqueous solution (hydrazine hydrate: water = 2:18) dropwise, continue stirring for 3 hours, and finally filter to obtain a high-property bio-based, self-crosslinking waterborne polyurethane resin.

[0038] Verification Example

[0039] The high-property bio-based, self-crosslinking waterborne polyurethane resin of the present invention (tested using the waterborne polyurethane resin obtained in Example 2) is used as a synthetic leather surface resin, and the specific test performance is as follows:

[0040] Table 1

[0041] Test samples Unoxidized cross-linked samples Sample after oxidative crosslinking Modulus 1.5 1.8 Breaking strength(MPa) 10 12 Elongation(%) 600 750 Water absorption (%) 14.67 9.85 Martin wear resistance (times) 6400 8500 Low temperature bending (-10℃) 25000 30000 Normal temperature bending resistance (25℃) 50000 65000 Dry rubbing fastness (times) 350 400 Wet rubbing fastness (times) 250 320

[0042] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A high-property bio-based, self-crosslinking waterborne polyurethane resin, characterized in that: The preparation method comprises the following raw materials in parts by weight: 10-30 parts of castor oil, 30-70 parts of macromolecular polyol, 4-10 parts of hydrophilic chain extender, 30-70 parts of diisocyanate, 4-10 parts of neutralizer and 5-10 parts of diamine chain extender.

2. The high-property bio-based, self-crosslinking waterborne polyurethane resin according to claim 1, characterized in that: The preparation method comprises the following raw materials in parts by weight: 20 parts of dehydrated castor oil, 45 parts of macromolecular polyol, 6 parts of hydrophilic chain extender, 45 parts of diisocyanate, 4.5 parts of neutralizer and 5 parts of diamine chain extender.

3. The high-property bio-based, self-crosslinking waterborne polyurethane resin according to claim 1 or 2, characterized in that: The macromolecular polyol includes polyether diol or polycarbonate diol.

4. The high-property bio-based, self-crosslinking waterborne polyurethane resin according to claim 1 or 2, characterized in that: The hydrophilic chain extender includes dimethylol propionic acid or dimethylol butyric acid.

5. The high-property bio-based, self-crosslinking waterborne polyurethane resin according to claim 1 or 2, characterized in that: The diisocyanate includes TDI, IPDI or hydrogenated MDI.

6. The high-property bio-based, self-crosslinking waterborne polyurethane resin according to claim 1 or 2, characterized in that: The neutralizing agent is triethylamine.

7. The high-property bio-based, self-crosslinking waterborne polyurethane resin according to claim 1 or 2, characterized in that: The diamine chain extender is ethylenediamine, isophoronediamine or hydrazine hydrate.

8. The method for preparing the high-property bio-based, self-crosslinking waterborne polyurethane resin according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: (1) mixing castor oil and macromolecular polyol, and performing vacuum dehydration under heating conditions to obtain an anhydrous primary mixture; (2) sequentially adding a hydrophilic chain extender and a diisocyanate to the anhydrous primary mixture, performing a first reaction under heating conditions, then cooling the mixture and adding a neutralizing agent to perform a second reaction to obtain a prepolymer; (3) Under stirring conditions, the prepolymer is added to deionized water, and finally a diamine chain extender aqueous solution is added dropwise, and after continuous stirring, a high-property bio-based, self-crosslinking waterborne polyurethane resin is obtained.

9. The preparation method according to claim 8, characterized in that: In step (1), the heating temperature is 100-110° C., and the vacuum dehydration time is 1-2 h.

10. The preparation method according to claim 8, characterized in that: In step (2), the first reaction is carried out at 80-85°C for 2-4 hours, and then the temperature is lowered to 73-75°C for a second reaction for 0.5 hour.