Plastic-replacing gloss oil based on ureido pyrimidone structure as well as preparation method and application of plastic-replacing gloss oil

Abstract

The invention provides plastic-replacing gloss oil based on a ureido pyrimidone structure and a preparation method and application thereof.The preparation method comprises the steps that quadruple hydrogen bond elements (UPy) containing the ureido pyrimidone structure are synthesized firstly, then UPy, hydrophilic modified polyol and an emulsifier are pre-polymerized, a waterborne polyurethane prepolymer containing the ureido pyrimidone structure is obtained, and the waterborne polyurethane prepolymer containing the ureido pyrimidone structure is subjected to curing to obtain the plastic-replacing gloss oil based on the ureido pyrimidone structure. The preparation method comprises the following steps: preparing UPy-containing waterborne polyurethane, reacting with a chain extender and a neutralizer to generate UPy-containing waterborne polyurethane, compounding the UPy-containing waterborne polyurethane with the components of the gloss oil, stirring and filtering to obtain the UPy-containing waterborne polyurethane, synthesizing a UPy quadruple hydrogen bond element by adopting a chemical method, and introducing the UPy quadruple hydrogen bond element into a main chain of a waterborne polyurethane molecular chain to prepare new film-forming resin. According to the plastic-replacing gloss oil, the flexibility and adhesive force of the plastic-replacing gloss oil after film forming are enhanced, the mechanical property of the plastic-replacing gloss oil is improved, the plastic-replacing gloss oil with excellent adhesive force, scraping resistance, wear resistance and bending resistance can be developed, the preparation process is simple, operability is high, the plastic-replacing gloss oil can be widely applied to the field of packaging, decoration and printing, and the value of commodities is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of varnishes, and in particular relates to a plastic-replacing varnish based on a ureidopyrimidone structure, and a preparation method and application thereof. Background Art

[0002] With the rapid development of the global economy and the continuous improvement of people's living standards, plastic products have been widely used in various fields. However, the extensive use of plastic products has also brought serious environmental problems, such as "white pollution". In order to solve these problems, governments around the world have introduced laws and policies to control "white pollution". A series of policies such as "plastic restriction order" and "plastic ban order" have been introduced at home and abroad, which has promoted the rapid development of degradable materials. In the packaging and printing industry, the traditional laminating process uses non-degradable plastic film, which is not only not environmentally friendly, but also increases the environmental burden. As an environmentally friendly material, plastic replacement varnish is of great significance under the plastic restriction order. It can replace the traditional laminating process, reduce the use of plastic products, and has the advantages of being degradable and not causing environmental pollution. It can significantly reduce the pollution of the packaging and printing industry to the environment.

[0003] At present, plastic replacement varnish, as an environmentally friendly material, meets the needs of consumers and has broad market prospects. At the same time, with the continuous advancement of technology, the performance of plastic replacement varnish is also constantly improving. For example, some plastic replacement varnish products have properties such as anti-scratch, folding resistance, and waterproofness, which can meet the needs of different fields. However, compared with the traditional lamination process, the commercially available plastic replacement varnish still has room for improvement in mechanical properties and adhesion. Summary of the invention

[0004] In order to overcome the shortcomings and disadvantages of existing plastic-replacing varnishes, the present invention aims to provide a plastic-replacing varnish based on a ureidopyrimidone structure which has good stretchability and glossiness, and has both printability and good adhesion.

[0005] This application adopts the following technical solutions: A plastic-replacing varnish based on a ureidopyrimidone structure comprises the following raw materials in parts by weight: 70-80% of a waterborne polyurethane resin based on a ureidopyrimidone structure, 8-15% of deionized water, 5-10% of a film-forming aid, and 2-8% of a varnish aid.

[0006] Furthermore, a waterborne polyurethane resin based on a ureidopyrimidone structure comprises the following components in parts by weight: 5 to 25 parts of a polyol, 1 to 20 parts of a polyisocyanate, 0.1 to 5 parts of a hydrophilically modified polyol, 1 to 20 parts of an acrylic monomer, 1 to 3 parts of a neutralizer, 0.1 to 3 parts of a chain extender, 0.5 to 5 parts of a silicon coupling agent, 0.01 to 1 parts of a catalyst, and 90 to 110 parts of deionized water.

[0007] Further preferably, a waterborne polyurethane resin based on a ureidopyrimidone structure comprises the following components in parts by weight: 15 to 25 parts of a polyol, 2 to 5 parts of a polyisocyanate, 0.1 to 2 parts of a hydrophilically modified polyol, 1 to 3 parts of an acrylic monomer, 1 to 2 parts of a neutralizer, 0.1 to 1 part of a chain extender, 0.5 to 2 parts of a silicon coupling agent, 0.01 to 1 part of a catalyst, and 90 to 110 parts of deionized water.

[0008] The ureidopyrimidone structure has unique hydrogen bonding and the characteristics of enhancing interfacial adhesion, which brings great potential to plastic-replacing varnishes. This application can develop plastic-replacing varnishes with excellent adhesion, scratch resistance, wear resistance, and bending resistance by introducing the ureidopyrimidone structure into the main chain of the waterborne polyurethane resin. Based on this, the development of high-performance plastic-replacing varnishes based on the ureidopyrimidone structure has important practical significance and research value, which can not only promote the development of environmentally friendly material technology, but also provide new ideas and methods for the research and development and application of environmentally friendly materials.

[0009] Preferably, the polyisocyanate is one or more combinations of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), and hexamethylene diisocyanate (HDI).

[0010] Preferably, the polyol is one or more combinations of polypropylene glycol, polytetramethylene glycol, polycaprolactone glycol and polycarbonate glycol.

[0011] Preferably, the hydrophilic modified polyol is one or more combinations of 2,2-bis(hydroxymethyl)propionic acid (DMPA) and 2,2-bis(hydroxymethyl)butanoic acid (DMBA).

[0012] Preferably, the chain extender is one or more combinations of adipic acid dihydrazide and ethylenediamine.

[0013] Preferably, the catalyst is one or more combinations of ammonium persulfate (APS) and dibutyltin dilaurate (DBTDL).

[0014] Preferably, the varnish additive comprises, by weight, 0.5 to 3 parts of a wetting and leveling agent, 0.5 to 3 parts of a defoaming agent, 0.1 to 0.5 parts of a thickener, and 1 to 3 parts of a crosslinking agent, and the varnish additive is a common component of varnish additives in the art.

[0015] The second purpose of the present application is to provide a method for preparing a plastic-replacing varnish based on a ureidopyrimidone structure, comprising the following steps: (1) Preparing a waterborne polyurethane resin based on ureidopyrimidone structure; (2) The aqueous polyurethane resin based on the ureidopyrimidone structure obtained in step (1), deionized water, aqueous film-forming agent, and varnish agent are mixed and stirred evenly according to a certain proportion, and finally filtered through a 150-mesh gauze to obtain the ureidopyrimidone structure-based plastic-replacing varnish.

[0016] The present application prepares a plastic-replacement varnish based on a urea-pyrimidone structure by first preparing a water-based polyurethane resin based on a urea-pyrimidone structure, and then adding a film-forming agent, water and related additives. This not only effectively replaces the traditional coating process, but also greatly improves the mechanical properties of the plastic-replacement varnish.

[0017] Specifically, a method for preparing a waterborne polyurethane resin based on a ureidopyrimidone structure comprises the following steps: S1. Put the polyol into a reaction kettle, vacuum dehydrate it at 100-110°C for 1-2h, and then cool it to 80-90°C; S2, adding polyisocyanate and hydrophilic modified polyol to react at 80-90°C for 2-4h, and then adding part of acrylic acid monomer to reduce viscosity according to the viscosity in the last hour; S3, lowering the system temperature to 55-65°C, adding the remaining acrylic acid monomer, then lowering the temperature to 45-55°C, adding a neutralizing agent and neutralizing for 5-15 minutes; S4, add deionized water to disperse under high-speed stirring, then cool to 30-40°C, drop chain extender, keep warm for 0.5-1.5h, then add silicon coupling agent; S5, raising the temperature to 70-80° C., adding a catalyst, and after the temperature rises to 80-90° C., maintaining the temperature for 0.5-1.5 hours, cooling and filtering the material to obtain the waterborne polyurethane resin based on the ureidopyrimidone structure.

[0018] The above-mentioned preparation method aims to solve the problem of poor mechanical properties of water-based polyurethane. By reacting polyols with polyisocyanates and silane coupling agents, the ureido-pyrimidone structure is successfully introduced into the water-based polyurethane system. The UPy quadruple hydrogen bond unit is synthesized by chemical methods and introduced into the main chain of the water-based polyurethane molecular chain. This can develop a plastic-replacing varnish with excellent adhesion, scratch resistance, wear resistance, bending resistance and other properties, and prepare a new film-forming resin.

[0019] The present application provides a method for preparing a plastic-replacement varnish based on a ureidopyrimidone structure. First, a quadruple hydrogen-bonding unit (UPy) containing a ureidopyrimidone structure is synthesized. Then, UPy is pre-polymerized with a hydrophilic modified polyol and an emulsifier to obtain a waterborne polyurethane prepolymer containing a ureidopyrimidone structure. Subsequently, the prepolymer is reacted with a chain extender and a neutralizer to generate a waterborne polyurethane (WUPy) containing UPy. Finally, WUPy is compounded with various components of the varnish, stirred and filtered to obtain a plastic-replacement varnish based on a ureidopyrimidone structure.

[0020] The third object of the present invention is to provide the application of the above-mentioned ureidopyrimidone-based plastic replacement varnish in the field of packaging and decoration printing. The present application uses a chemical grafting method to synthesize the UPy quadruple hydrogen bond unit ( Figure 1 ), which is introduced into the main chain of the waterborne polyurethane molecular chain ( Figure 2 ), which enhances the flexibility and adhesion of the plastic replacement varnish after film formation, and improves the mechanical properties of the plastic replacement varnish. It can be widely used in the field of packaging, decoration and printing to enhance the value of the product.

[0021] Compared with the prior art, the present invention has the following advantages: The invention provides a plastic-replacement varnish based on a ureidopyrimidone structure, and a preparation method and application thereof. Firstly, a quadruple hydrogen-bonding unit (UPy) containing a ureidopyrimidone structure is synthesized, and then UPy is prepolymerized with a hydrophilic modified polyol and an emulsifier to obtain an aqueous polyurethane prepolymer containing a ureidopyrimidone structure, which is then reacted with a chain extender and a neutralizer to generate an aqueous polyurethane containing UPy, and finally the aqueous polyurethane prepolymer is compounded with various components of varnish, stirred and filtered to obtain a plastic-replacement varnish based on a ureidopyrimidone structure. The UPy quadruple hydrogen-bonding unit is synthesized by a chemical method, and introduced into the main chain of the aqueous polyurethane molecular chain, thereby enhancing the flexibility and adhesion of the plastic-replacement varnish after film formation, improving the mechanical properties of the plastic-replacement varnish, and developing a plastic-replacement varnish with excellent adhesion, scratch resistance, wear resistance and bending resistance. The invention has a simple preparation process and strong operability, and can be widely used in the field of packaging, decoration and printing to enhance the value of commodities. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for describing the embodiments are briefly introduced below.

[0023] Figure 1 is an infrared image of the UPy quadruple hydrogen bond motif in the embodiment of the present application; Figure 2 This is an infrared image of a waterborne polyurethane having a ureidopyrimidone structure introduced in an example of the present application. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. 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. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0025] Example 1 A method for preparing a plastic-replacing varnish based on a ureidopyrimidone structure comprises the following steps: (1) First, put 20.0g of polypropylene glycol into a dry reactor, vacuum dehydrate at 100℃ for 1h, and then cool to 80℃. Then, add 2.87g of toluene diisocyanate and 1.2g of 2,2-bis(hydroxymethyl)propionic acid and react at 80℃ for 3h, and then add 1.0g of acrylic acid 1h later. After that, lower the system temperature to 60℃, add 0.5g of acrylic acid monomer, cool to 50℃, and add 1.15g of triethylamine to neutralize for 10min. Add 100g of deionized water under high-speed stirring for dispersion, then cool to 35℃, add 0.5g of ethylenediamine dropwise, keep warm for 1h, and then add 1.0g of silicon coupling agent. Finally, heat to 75℃, add 0.5g of dibutyltin dilaurate, and keep warm for 1h after the temperature rises to 90℃. After cooling and filtering, a water-based polyurethane resin based on ureidopyrimidone structure is obtained; (2) The aqueous polyurethane resin based on the ureidopyrimidone structure prepared in step (1), deionized water, aqueous film-forming aid, leveling agent, defoaming agent, thickener, cross-linking agent and other additives are mixed and stirred uniformly in a ratio of 75.00%, 12.50%, 8.40%, 1.50%, 1.50%, 0.10% and 1.00% relative to the total mass of the varnish, respectively, and finally filtered through a 150-mesh gauze to obtain a ureidopyrimidone structure-based plastic replacement varnish.

[0026] Example 2 A method for preparing a plastic-replacing varnish based on a ureidopyrimidone structure comprises the following steps: (1) First, 25.0g of polytetrahydrofuran ether diol was put into a dry reactor, vacuum dehydrated at 100℃ for 1.5h, and then cooled to 85℃. Then, 3.0g of diphenylmethane diisocyanate and 1.5g of 2,2-bis(hydroxymethyl)propionic acid were added and reacted at 80℃ for 3h, and 1.2g of acrylic acid was added after 1h. After that, the system temperature was lowered to 60℃, and 0.8g of acrylic acid monomer was added, and then the temperature was lowered to 50℃, and 1.2g of triethylamine was added for neutralization for 15min. 95g of deionized water was added under high-speed stirring to disperse, and then the temperature was lowered to 35℃, 0.4g of ethylenediamine was added dropwise, and 1.1g of silicon coupling agent was added after keeping the temperature for 1h. Finally, the temperature was raised to 75℃, 0.6g of dibutyltin dilaurate was added, and the temperature was raised to 80℃ and kept for 1h. After cooling and filtering the material, a water-based polyurethane resin based on ureidopyrimidone structure is obtained; (2) The aqueous polyurethane resin based on the ureidopyrimidone structure prepared in step (1), deionized water, aqueous film-forming aid, leveling agent, defoaming agent, thickener, cross-linking agent and other additives are mixed and stirred uniformly in a ratio of 74.00%, 13.80%, 10.00%, 0.50%, 0.50%, 0.20% and 1.00% relative to the total mass of the varnish, respectively, and finally filtered through a 150-mesh mesh to obtain a ureidopyrimidone structure-based plastic replacement varnish.

[0027] Example 3 A method for preparing a plastic-replacing varnish based on a ureidopyrimidone structure comprises the following steps: (1) First, 22.0g of polycaprolactone diol was put into a dry reactor, vacuum dehydrated at 110℃ for 1h, and then cooled to 85℃. Then, 2.95g of dicyclohexylmethane diisocyanate and 1.5g of 2,2-bis(hydroxymethyl)butyric acid were added to react at 85℃ for 3h, and 1.5g of acrylic acid was added after 1h. After that, the system temperature was lowered to 60℃, and 0.6g of acrylic acid monomer was added, and then the temperature was lowered to 50℃, and 1.1g of triethylamine was added for neutralization for 10min. 102g of deionized water was added under high-speed stirring to disperse, and then the temperature was lowered to 35℃, 0.4g of adipic acid dihydrazide was added dropwise, and 1.0g of silicon coupling agent was added after keeping the temperature for 1h. Finally, the temperature was raised to 75℃, 0.5g of ammonium persulfate was added, and the temperature was raised to 80℃ and kept for 1h. After cooling and filtering the material, a water-based polyurethane resin based on ureidopyrimidone structure is obtained; (2) The aqueous polyurethane resin based on the ureidopyrimidone structure prepared in step (1), deionized water, aqueous film-forming aid, leveling agent, defoaming agent, thickener, cross-linking agent and other additives are mixed and stirred uniformly in a ratio of 78.00%, 10.00%, 8.20%, 1.00%, 0.50%, 0.30% and 2.00% relative to the total mass of the varnish, respectively, and finally filtered through a 150-mesh gauze to obtain a ureidopyrimidone structure-based plastic replacement varnish.

[0028] Example 4 A method for preparing a plastic-replacing varnish based on a ureidopyrimidone structure comprises the following steps: (1) First, 20.0g of polycarbonate diol was put into a dry reactor, vacuum dehydrated at 100℃ for 1h, and then cooled to 85℃. Then, 2.80g of hexamethylene diisocyanate and 1.5g of 2,2-bis(hydroxymethyl)propionic acid were added and reacted at 80℃ for 3h, and 2.0g of acrylic acid was added after 1h. After that, the system temperature was lowered to 60℃, and 0.5g of acrylic acid monomer was added, and then the temperature was lowered to 50℃, and 1.0g of triethylamine was added for neutralization for 15min. 106.5g of deionized water was added under high-speed stirring to disperse, and then the temperature was lowered to 35℃, 0.5g of ethylenediamine was added dropwise, and 1.0g of silicon coupling agent was added after keeping the temperature for 1h. Finally, the temperature was raised to 75℃, 0.5g of dibutyltin dilaurate was added, and the temperature was raised to 85℃ and kept for 1h. After cooling and filtering the material, a water-based polyurethane resin based on ureidopyrimidone structure is obtained; (2) The aqueous polyurethane resin based on the ureidopyrimidone structure prepared in step (1), deionized water, aqueous film-forming aid, leveling agent, defoaming agent, thickener, cross-linking agent and other additives are mixed and stirred uniformly in a ratio of 80.00%, 11.20%, 6.50%, 0.50%, 0.50%, 0.30% and 1.00% relative to the total mass of the varnish, respectively, and finally filtered through a 150-mesh gauze to obtain a ureidopyrimidone structure-based plastic replacement varnish.

[0029] Example 5 A method for preparing a plastic-replacing varnish based on a ureidopyrimidone structure comprises the following steps: (1) First, put 18.0g of polypropylene glycol into a dry reactor, vacuum dehydrate at 110℃ for 1h, and then cool to 90℃. Next, add 2.50g of diphenylmethane diisocyanate and 1.4g of 2,2-bis(hydroxymethyl)propionic acid and react at 85℃ for 3h, and then add 1.5g of acrylic acid 1h later. After that, lower the system temperature to 60℃, add 1.0g of acrylic acid monomer, cool to 50℃, and add 1.3g of triethylamine to neutralize for 10min. Add 105g of deionized water under high-speed stirring to disperse, then cool to 35℃, add 0.5g of ethylenediamine dropwise, keep warm for 1h, and then add 1.2g of silicon coupling agent. Finally, heat to 75℃, add 0.5g of ammonium persulfate, and keep warm for 1h after the temperature rises to 80℃. After cooling and filtering, a water-based polyurethane resin based on ureidopyrimidone structure is obtained; (2) The aqueous polyurethane resin based on the ureidopyrimidone structure prepared in step (1), deionized water, aqueous film-forming aid, leveling agent, defoaming agent, thickener, cross-linking agent and other additives are mixed and stirred uniformly in a ratio of 71.00%, 15.00%, 10.00%, 1.00%, 1.00%, 0.40% and 1.60% relative to the total mass of the varnish, respectively, and finally filtered through a 150-mesh mesh to obtain a ureidopyrimidone structure-based plastic replacement varnish.

[0030] Example 6 A method for preparing a plastic-replacing varnish based on a ureidopyrimidone structure comprises the following steps: (1) First, 20.5g of polycaprolactone diol was put into a dry reactor, vacuum dehydrated at 110℃ for 1h, and then cooled to 90℃. Then, 2.60g of hexamethylene diisocyanate and 1.5g of 2,2-bis(hydroxymethyl)propionic acid were added to react at 80℃ for 3h, and 2.0g of acrylic acid was added after 1h. After that, the system temperature was lowered to 60℃, and 0.5g of acrylic acid monomer was added, and then the temperature was lowered to 50℃, and 1.0g of triethylamine was added for neutralization for 15min. 106.5g of deionized water was added under high-speed stirring to disperse, and then the temperature was lowered to 35℃, 0.5g of adipic acid dihydrazide was added dropwise, and 1.2g of silicon coupling agent was added after keeping the temperature for 1h. Finally, the temperature was raised to 75℃, 0.5g of dibutyltin dilaurate was added, and the temperature was raised to 85℃ and kept for 1h. After cooling and filtering the material, a water-based polyurethane resin based on ureidopyrimidone structure is obtained; (2) The aqueous polyurethane resin based on the ureidopyrimidone structure prepared in step (1), deionized water, aqueous film-forming aid, leveling agent, defoamer, thickener, cross-linking agent and other additives are mixed and stirred uniformly in a ratio of 73.00%, 13.50%, 9.00%, 1.00%, 1.00%, 0.50% and 2.00% relative to the total mass of the varnish, respectively, and finally filtered through a 150-mesh mesh to obtain a ureidopyrimidone structure-based plastic replacement varnish.

[0031] Effect Example The performance of the plastic-replacing varnish based on the ureidopyrimidone structure prepared in Examples 1-6 was tested. The test results are shown in Table 1.

[0032] Table 1: Performance test results

[0033] Experiments show that the plastic-replacing varnish based on urea-pyrimidone structure prepared by the present invention has the characteristics of wear resistance, folding resistance and explosion resistance, good adhesion to the substrate, no back-sticking, good adhesion, good gloss after oiling, and good yellowing resistance of the film surface. It can be widely used in medical, electronic equipment, cosmetics, and educational packaging, and can replace the traditional OPP light film process that is non-degradable such as film and plastic, and has the advantage of being degradable and will not cause environmental pollution.

[0034] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A plastic-replacing varnish based on a ureidopyrimidone structure, characterized in that: The method comprises the following raw materials in parts by weight: 70-80% of waterborne polyurethane resin based on ureidopyrimidone structure, 8-15% of deionized water, 5-10% of film-forming agent, and 2-8% of varnish agent; The waterborne polyurethane resin based on ureidopyrimidone structure includes the following components in parts by weight: 5 to 25 parts of polyol, 1 to 20 parts of polyisocyanate, 0.1 to 5 parts of hydrophilic modified polyol, 1 to 20 parts of acrylic monomer, 1 to 3 parts of neutralizer, 0.1 to 3 parts of chain extender, 0.5 to 5 parts of silicon coupling agent, 0.01 to 1 parts of catalyst and 90 to 110 parts of deionized water.

2. The plastic-replacing varnish based on ureidopyrimidone structure according to claim 1, characterized in that: The polyisocyanate is one or more combinations of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), and hexamethylene diisocyanate (HDI).

3. The plastic-replacing varnish based on ureidopyrimidone structure according to claim 1, characterized in that: The polyol is one or more combinations of polypropylene glycol, polytetramethylene glycol, polycaprolactone glycol and polycarbonate glycol.

4. The plastic-replacing varnish based on ureidopyrimidone structure according to claim 1, characterized in that: The hydrophilic modified polyol is one or more combinations of 2,2-bis(hydroxymethyl)propionic acid (DMPA) and 2,2-bis(hydroxymethyl)butanoic acid (DMBA).

5. The plastic-replacing varnish based on ureidopyrimidone structure according to claim 1, characterized in that: The chain extender is one or more combinations of adipic acid dihydrazide and ethylenediamine.

6. The plastic-replacing varnish based on ureidopyrimidone structure according to claim 1, characterized in that: The catalyst is one or more combinations of ammonium persulfate (APS) and dibutyltin dilaurate (DBTDL).

7. The plastic-replacing varnish based on ureidopyrimidone structure according to claim 1, characterized in that: The varnish additive comprises, by weight, 0.5 to 3 parts of a wetting and leveling agent, 0.5 to 3 parts of a defoaming agent, 0.1 to 0.5 parts of a thickener, and 1 to 3 parts of a cross-linking agent.

8. The method for preparing a plastic-replacing varnish based on a ureidopyrimidone structure according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Preparation of waterborne polyurethane resin based on ureidopyrimidone structure; (2) The aqueous polyurethane resin based on the ureidopyrimidone structure obtained in step (1), deionized water, aqueous film-forming agent, and varnish agent are mixed and stirred evenly according to a certain proportion, and finally filtered through a 150-mesh gauze to obtain the ureidopyrimidone structure-based plastic-replacing varnish.

9. The method for preparing the plastic-replacing varnish based on the ureidopyrimidone structure according to claim 8, characterized in that: The waterborne polyurethane resin based on ureidopyrimidone structure comprises the following steps: S1. Put the polyol into a reaction kettle, vacuum dehydrate it at 100-110°C for 1-2h, and then cool it to 80-90°C; S2, adding polyisocyanate and hydrophilic modified polyol to react at 80-90°C for 2-4h, and then adding part of acrylic acid monomer to reduce viscosity in the last hour; S3, lowering the system temperature to 55-65°C, adding the remaining acrylic acid monomer, then lowering the temperature to 45-55°C, adding a neutralizing agent and neutralizing for 5-15 minutes; S4, add deionized water to disperse under high-speed stirring, then cool to 30-40°C, drop chain extender, keep warm for 0.5-1.5h, then add silicon coupling agent; S5, raising the temperature to 70-80° C., adding a catalyst, and after the temperature rises to 80-90° C., maintaining the temperature for 0.5-1.5 hours, cooling and filtering the material to obtain the waterborne polyurethane resin based on the ureidopyrimidone structure.

10. Use of the ureidopyrimidone-based plastic-replacement varnish according to any one of claims 1 to 7 in the field of packaging and decoration printing.

Images