Hyperbranched light-cured polyurethane acrylate resin as well as preparation method and application thereof

Abstract

The invention relates to hyperbranched light-cured polyurethane acrylate resin as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) reacting polyisocyanate containing a uretdione group with polyhydric alcohol to prepare hydroxyl-terminated hyperbranched polyurethane resin containing the uretdione group; and (2) preparing the hyperbranched light-cured polyurethane acrylate resin containing the biuret group by reacting an acrylate compound containing an amino group with the hydroxyl-terminated hyperbranched polyurethane resin containing the uretdione group prepared in the step (1). The prepared light-cured resin has low viscosity, good adhesive force and flexibility, and is suitable for various application scenes such as 3C coatings, wood lacquer, nail polish glue and waterproof coatings.

Description

Technical Field

[0001] The present invention belongs to the field of photocurable resins, and particularly relates to a hyperbranched photocurable polyurethane acrylate resin with excellent adhesion, a preparation method thereof, and an application thereof. Background Art

[0002] As a green photocuring technology, ultraviolet (UV) photocuring technology has attracted extensive attention since the 1960s due to its green environmental protection, energy conservation and high efficiency, and low investment. The UV photocuring technology not only plays a huge role in the surface decoration of products such as wood, paper, metal, plastic, and glass, but also is widely used in application fields such as inks, adhesives, and photoresists.

[0003] The components of a UV photocuring system generally include a photocurable resin, a photoinitiator, an additive, and an active diluent, etc. Among them, the photocurable resin is the most crucial factor determining the performance. The photocurable polyurethane acrylate resin has been widely used due to its good flexibility, wear resistance, etc.

[0004] Hyperbranched polyurethane acrylate resin is a kind of polymer resin with a special structure. Compared with traditional polyurethane acrylate resin, it has lower viscosity and better solubility, can significantly reduce the viscosity of the system, reduce the use of active diluent, and the final product has better flexibility. Moreover, the synthesis process of hyperbranched resin is simple, which is conducive to large-scale industrial production. Therefore, it has broad application prospects.

[0005] In recent years, a large number of studies have been carried out by researchers on the synthesis of hyperbranched polyurethane acrylate resin. Patent CN 107903372A obtained a photocurable flexible hyperbranched polyurethane acrylate resin by grafting flexible polyurethane acrylate onto a hyperbranched polyurethane with terminal hydroxyl groups. This patent needs to separately prepare the hyperbranched polyurethane with terminal hydroxyl groups and the flexible polyurethane acrylate, and then carry out the polymerization reaction between the two. The reaction requires processes such as precipitation, solvent washing, and vacuum drying, and the process is relatively complex. Patent CN 108314773B prepared hyperbranched polyol through a stepwise esterification branching synthesis process, and then prepared a hyperbranched polyurethane acrylate resin through reaction with ethyl isocyanate acrylate. The prepared resin has a relatively fast curing speed and a relatively low viscosity. However, at present, after the hyperbranched polyurethane acrylate resin is photocured, there are still problems such as a large crosslinking density and fewer flexible chain segments, and the products often have problems such as poor flexibility, brittleness, and poor adhesion.

[0006] Therefore, it is necessary to develop a hyperbranched photocurable polyurethane acrylate resin with low viscosity, good flexibility, and excellent adhesion. Summary of the Invention

[0007] In view of the above problems existing in the prior art, the present invention provides a hyperbranched photocurable polyurethane acrylate resin and a preparation method. The present invention creatively breaks through the traditional method of using hydroxyl-containing acrylate to cap and provide photocurable groups, and utilizes the special structure of isocyanurate to introduce biuret groups and photocurable groups. The prepared resin has the advantages of low viscosity, good flexibility and excellent adhesion, and is suitable for various application scenarios such as 3C coatings, wood coatings, nail polishes, waterproof coatings, etc.

[0008] To achieve the above object, the present invention is realized through the following technical solutions:

[0009] The present invention provides a preparation method of a hyperbranched photocurable polyurethane acrylate resin, and the steps include:

[0010] (1) Reacting a polyisocyanate containing a uretdione group with a polyol to prepare a hyperbranched polyurethane resin with a uretdione group at the end and a hydroxyl group;

[0011] (2) Reacting an acrylate compound containing an amino group with the hyperbranched polyurethane resin with a uretdione group at the end and a hydroxyl group prepared in step (1) to prepare a hyperbranched photocurable polyurethane acrylate resin containing a biuret group.

[0012] In a specific example, step (1) is to react a polyisocyanate containing a uretdione group with a polyol under the action of catalyst A to prepare a hyperbranched polyurethane resin with a uretdione group at the end and a hydroxyl group.

[0013] Preferably, in step (1), each raw material is in parts by mass, including: 170-220 parts of a polyisocyanate containing a uretdione group, such as 170, 180, 190, 200, 210, 220 parts; 150-800 parts of a polyol, such as 150, 200, 300, 400, 500, 600, 700, 800 parts; 0.2-2 parts of catalyst A, such as 0.2, 0.5, 0.8, 1.1, 1.4, 1.7, 2 parts.

[0014] Preferably, the polyisocyanate containing a uretdione group in step (1) is selected from uretdione diisocyanate, preferably one or more of hexamethylene diisocyanate uretdione, pentamethylene diisocyanate uretdione, isophorone diisocyanate uretdione, toluene diisocyanate uretdione, diphenylmethane-4,4'-diisocyanate uretdione, and preferably hexamethylene diisocyanate uretdione, such as WANNATE HT-400 (polyhexamethylene diisocyanate) of Wanhua Chemical.

[0015] The polyisocyanate containing a uredione group described in the present invention is a product already disclosed in the prior art, and there are no special requirements for its source. It can be purchased or prepared by oneself. The self-preparation method can refer to the methods disclosed in CN112851908A, CN112574388A, etc., and can be prepared by a polymerization reaction from polyisocyanates such as hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), isophorone diisocyanate (IPDI), etc.

[0016] Preferably, the polyol in step (1) is selected from one or more of polyethylene glycol, polypropylene glycol, polytetrahydrofuran ether diol, polyoxytetramethylene glycol, trimethylolpropane, glycerol, pentaerythritol, ethoxylated trimethylolpropane, ethoxylated pentaerythritol, poly(oxy-1,2-propylene) glycol, castor oil polyol, and is preferably one or more of polypropylene glycol, polytetrahydrofuran ether diol, trimethylolpropane, and pentaerythritol.

[0017] Preferably, the catalyst A in step (1) is selected from one or more of organotin compounds, organobismuth compounds, and organozinc compounds, and is preferably one or more of dibutyltin dilaurate, dioctyltin dilaurate, and stannous octoate.

[0018] Preferably, for the reaction in step (1), the temperature is 50 - 100 °C, such as 50, 60, 70, 80, 90, 100 °C, and the reaction end point is when the NCO in the system reacts completely.

[0019] In a specific example, step (2) is a reaction of an acrylate compound containing an amino group with the uredione group-containing hydroxyl-terminated hyperbranched polyurethane resin prepared in step (1) under the action of catalyst B to obtain a hyperbranched photocurable polyurethane acrylate resin containing a biuret group.

[0020] Preferably, based on parts by mass, the raw materials used in step (2) include: 200 - 800 parts of the uredione group-containing hydroxyl-terminated hyperbranched polyurethane resin, such as 200, 300, 400, 500, 600, 700, 800 parts; 50 - 300 parts of the acrylate compound containing an amino group, such as 50, 100, 150, 200, 250, 300 parts; 0.4 - 2 parts of catalyst B, such as 0.4, 0.5, 0.8, 1.1, 1.4, 1.7, 2 parts.

[0021] Preferably, the acrylate compound containing an amino group is selected from one or more of dimethylacrylamide carbamate, 2-(acetamido)ethyl methacrylate, and 2-aminoethyl methacrylate.

[0022] Preferably, the catalyst B is selected from one or more of dibutyltin dilaurate, dioctyltin dilaurate, tetrabutylammonium trimethylacetate, and tetrabutylammonium acetate.

[0023] Preferably, for the reaction in step (2), the temperature is 60 - 100 °C, such as 60, 70, 80, 90, 100 °C, and the reaction end point is when the uretdione groups in the system react completely.

[0024] The present invention also provides a hyperbranched photocurable polyurethane acrylate resin prepared by the above method.

[0025] The hyperbranched photocurable polyurethane acrylate resin of the present invention has a viscosity of 5000 - 50000 mPa·s at 25 °C, such as 5000, 10000, 20000, 30000, 40000, 50000 mPa·s.

[0026] The hyperbranched photocurable polyurethane acrylate resin of the present invention has low viscosity, good flexibility and excellent adhesion, and can show good adhesion on plastics, wood, and metal parts without using an adhesion promoter, and is suitable for fields such as 3C coatings, wood coatings, nail polishes, and waterproof coatings.

[0027] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0028] (1) The prepared hyperbranched photocurable polyurethane acrylate resin has a low viscosity, can effectively reduce the use of reactive diluents, and greatly reduces the odor of the system.

[0029] (2) The prepared hyperbranched photocurable polyurethane acrylate resin has a special biuret structure, wide substrate applicability, and can show good adhesion on plastics, wood, and metal parts without using an adhesion promoter.

[0030] (3) The prepared hyperbranched photocurable polyurethane acrylate resin has good flexibility and mechanical properties, and is suitable for various application scenarios such as 3C coatings, wood coatings, nail polishes, and waterproof coatings. Detailed implementation manners

[0031] The following implementation examples are used to describe the solution of the present invention in more detail, but the present invention is not limited to the solution described in the examples.

[0032] The sources of the main raw materials in each implementation example and comparative example of the present invention are as follows. Other raw materials and reagents are obtained through commercial channels in the market without special instructions:

[0033] WANNATE HT - 400: Wanhua Chemical;

[0034] WANNATE PD (Pentamethylene Diisocyanate Uretdione): Wanhua Chemical;

[0035] HDI: Wanhua Chemical;

[0036] Polypropylene glycol: Wanhua Chemical;

[0037] Polytetrahydrofuran ether glycol: Huafeng Group;

[0038] Pentaerythritol: Guangzhou Haoyu International Trade Co., Ltd.;

[0039] Dibutyltin dilaurate: Aladdin Reagent;

[0040] 2-Hydroxyethyl methacrylate: Wanhua Chemical;

[0041] Dimethylacrylamide carbamate: Hubei Guangao Biotech Co., Ltd.

[0042] 2-(Acetylamino)ethyl methacrylate: Hubei Guangao Biotech Co., Ltd.;

[0043] Tetrabutylammonium acetate: Jinan Luxin Chemical Technology Co., Ltd.

[0044] Example 1

[0045] To prepare hyperbranched photocurable polyurethane acrylate resin, the steps are as follows:

[0046] (1) Place 180 g of polyhexamethylene diisocyanate (Wanhua Chemical WANNATE HT-400), 250 g of polypropylene glycol 1000, 20 g of pentaerythritol, and 0.5 g of dibutyltin dilaurate in a reaction flask, react at 80 °C, monitor the NCO content in the system until the reaction is complete, and obtain a hyperbranched polyurethane resin with uretdione groups at the end hydroxyl groups.

[0047] (2) Place 450 g of the hyperbranched polyurethane resin with uretdione groups at the end hydroxyl groups, 100 g of 2-(acetylamino)ethyl methacrylate, 0.5 g of dibutyltin dilaurate, and 0.5 g of tetrabutylammonium acetate in a reaction flask, react at 90 °C, and use infrared spectroscopy to monitor the uretdione group signal at 1768 cm -1 until the signal basically disappears, and prepare a hyperbranched photocurable polyurethane acrylate resin containing biuret groups.

[0048] The prepared photocurable polyurethane acrylate resin has a clear and transparent appearance, and its viscosity at 25 °C is about 12000 mPa·s.

[0049] Example 2

[0050] To prepare hyperbranched photocurable polyurethane acrylate resin, the steps are as follows:

[0051] (1) Place 200 g of polyhexamethylene diisocyanate (WANNATE HT-400 from Wanhua Chemical), 125 g of polypropylene glycol 1000, 30 g of pentaerythritol, and 0.8 g of dibutyltin dilaurate in a reaction flask, react at 60 °C, monitor the NCO content of the system until the reaction is complete, and obtain a hydroxyl-terminated hyperbranched polyurethane resin containing uretdione groups.

[0052] (2) Place 350 g of the hydroxyl-terminated hyperbranched polyurethane resin containing uretdione groups, 105 g of 2-(acetamido)ethyl methacrylate, 0.3 g of dibutyltin dilaurate, and 0.6 g of tetrabutylammonium acetate in a reaction flask, react at 100 °C, and use infrared spectroscopy to monitor the uretdione group signal at 1768 cm -1 until the signal basically disappears, and prepare a hyperbranched photocurable polyurethane acrylate resin containing biuret groups.

[0053] The prepared photocurable polyurethane acrylate resin has a clear and transparent appearance, and its viscosity at 25 °C is about 8000 mPa·s.

[0054] Example 3

[0055] Prepare a hyperbranched photocurable polyurethane acrylate resin, and the steps are as follows:

[0056] (1) Place 175 g of WANNATE PD, 162 g of polytetrahydrofuran ether glycol 650, 20 g of pentaerythritol, and 0.6 g of dibutyltin dilaurate in a reaction flask, react at 70 °C, monitor the NCO content of the system until the reaction is complete, and obtain a hydroxyl-terminated hyperbranched polyurethane resin containing uretdione groups.

[0057] (2) Place 400 g of the hydroxyl-terminated hyperbranched polyurethane resin containing uretdione groups, 135 g of dimethylacrylamide carbamate, 0.3 g of dibutyltin dilaurate, and 0.6 g of tetrabutylammonium acetate in a reaction flask, react at 80 °C, and use infrared spectroscopy to monitor the uretdione group signal at 1768 cm -1 until the signal basically disappears, and prepare a hyperbranched photocurable polyurethane acrylate resin containing biuret groups.

[0058] The prepared photocurable polyurethane acrylate resin has a clear and transparent appearance, and its viscosity at 25 °C is about 13000 mPa·s.

[0059] Comparative Example 1

[0060] 84 g of hexamethylene diisocyanate, 162 g of polytetrahydrofuran ether diol 650, 15 g of pentaerythritol, and 1 g of dibutyltin dilaurate were placed in a reaction flask and reacted at 70 °C. The NCO content of the system was monitored. After reaching the theoretical value, 13 g of hydroxyethyl methacrylate was added, and the NCO was continuously monitored until the reaction was complete, obtaining a hyperbranched polyurethane acrylate resin.

[0061] The prepared photocurable polyurethane acrylate resin had a clear and transparent appearance, and its viscosity at 25 °C was about 20000 mPa·s.

[0062] Comparative Example 2

[0063] 190 g of polyhexamethylene diisocyanate (WANNATE HT-100 from Wanhua Chemical), 450 g of polypropylene glycol 1000, and 1 g of dibutyltin dilaurate were placed in a reaction flask and reacted at 80 °C. The NCO content of the system was monitored. After reaching the theoretical value, 13 g of hydroxyethyl methacrylate was added, and the NCO was continuously monitored until the reaction was complete, obtaining a hyperbranched polyurethane acrylate resin.

[0064] The prepared photocurable polyurethane acrylate resin had a clear and transparent appearance, and its viscosity at 25 °C was about 30000 mPa·s.

[0065] Comparative Example 3

[0066] Referring to the method of Example 1, the difference was only that: step 2) was omitted, and other operations and conditions remained unchanged, obtaining a photocurable polyurethane acrylate resin containing uretdione groups.

[0067] Performance testing of the photocurable polyurethane acrylate resins prepared in the examples and comparative examples of the present invention

[0068] 20 parts of each of the resins prepared in Examples 1-3 and Comparative Examples 1-3 were taken, 8 parts of hydroxyethyl methacrylate were taken, and 0.6 part of photoinitiator 184 was added. After mixing evenly, it was coated on an ABS substrate and cured with an ultraviolet lamp to obtain a film with a thickness of about 20 μm. The film properties were tested respectively, and the results are shown in Table 1 below:

[0069] The following methods were used to test each property:

[0070] Pencil hardness: Refer to GB / T 6739-2006 Paints and varnishes - Pencil method for the determination of film hardness;

[0071] Adhesion: Refer to GB / T 9286-2021 Paints and varnishes - Cross-cut test;

[0072] Flexibility: Refer to GB / T 1731-2020 Determination method for flexibility of paint films and putty films;

[0073] Water resistance: Refer to the method for determining water resistance of paint films in GB / T 1733-1993;

[0074] Acid resistance: Refer to the method for determining chemical reagent resistance of paint films in GB / T 1763-1979.

[0075] Table 1 Performance test results of Examples 1-3 and Comparative Examples 1-3

[0076] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Pencil hardness 3H 3H 3H 2H 4H 2H Adhesion (Cross-cut method) / grade 0 0 1 3 4 3 Flexibility / mm 2 2 3 5 6 3 Water resistance ≥7d ≥7d ≥7d 4d blistering 2d blistering 4d blistering <![CDATA[Acid resistance (10% H2SO4)]]> ≥5d ≥5d ≥5d 2d blistering 2d blistering 3d blistering

Claims

1. A preparation method of a hyperbranched photocurable polyurethane acrylate resin, characterized in that the steps Comprising: (1) Preparing a hydroxyl-terminated hyperbranched polyurethane resin containing a uretdione group by reacting a polyisocyanate containing a uretdione group with a polyol; (2) Preparing a hyperbranched photocurable polyurethane acrylate resin containing a biuret group by reacting an acrylate compound containing an amino group with the hydroxyl-terminated hyperbranched polyurethane resin containing a uretdione group prepared in step (1).

2. The preparation method according to claim 1, characterized in that Step (1) is to react a polyisocyanate containing a uretdione group with a polyol under the action of catalyst A to obtain a hydroxyl-terminated hyperbranched polyurethane resin containing a uretdione group; Preferably, in terms of parts by mass, the raw materials used in step (1) include: 170 - 220 parts of a polyisocyanate containing a uretdione group; 150 - 800 parts of a polyol; 0.2 - 2 parts of catalyst A; Preferably, catalyst A in step (1) is selected from one or more of organotin, organobismuth, and organozinc, preferably one or more of dibutyltin dilaurate, dioctyltin dilaurate, and stannous octoate.

3. The preparation method according to claim 1 or 2, characterized in that The polyisocyanate containing a uretdione group in step (1) is selected from uretdione diisocyanate, preferably one or more of hexamethylene diisocyanate uretdione, pentamethylene diisocyanate uretdione, isophorone diisocyanate uretdione, toluene diisocyanate uretdione, diphenylmethane - 4,4'-diisocyanate uretdione, preferably hexamethylene diisocyanate uretdione.

4. The preparation method according to claim 1 or 2, characterized in that The polyol in step (1) is selected from one or more of polyethylene glycol, polypropylene glycol, polytetrahydrofuran ether glycol, polyoxytetramethylene glycol, trimethylolpropane, glycerol, pentaerythritol, ethoxylated trimethylolpropane, ethoxylated pentaerythritol, poly(oxy - 1,2 - propylene) glycol, and castor oil polyol, preferably one or more of polypropylene glycol, polytetrahydrofuran ether glycol, trimethylolpropane, and pentaerythritol.

5. The preparation method according to claim 1 or 2, characterized in that For the reaction in step (1), the temperature is 50 - 100°C, and the reaction end point is when the NCO in the system reacts completely.

6. The preparation method according to claim 1, characterized in that Step (2) is to react an acrylate compound containing an amino group with the hydroxyl-terminated hyperbranched polyurethane resin containing a uretdione group prepared in step (1) under the action of catalyst B to obtain a hyperbranched photocurable polyurethane acrylate resin containing a biuret group; Preferably, in terms of parts by mass, the raw materials used in step (2) include: 200 - 800 parts of a hydroxyl-terminated hyperbranched polyurethane resin containing a uretdione group; 50 - 300 parts of an acrylate compound containing an amino group; 0.4 - 2 parts of catalyst B; Preferably, catalyst B is selected from one or more of dibutyltin dilaurate, dioctyltin dilaurate, tetrabutylammonium trimethylacetate, and tetrabutylammonium acetate.

7. The preparation method according to claim 1 or 6, characterized in that The acrylate compound containing an amino group is selected from one or more of dimethylaminoethyl methacrylate, 2-(acetamido)ethyl methacrylate, and 2 - aminoethyl methacrylate.

8. The preparation method according to claim 1 or 6, characterized in that For the reaction in step (2), the temperature is 60 - 100°C, and the reaction end point is when the uretdione group in the system reacts completely.

9. A hyperbranched photocurable polyurethane acrylate resin prepared by the method according to any one of claims 1-8, characterized in that Its viscosity at 25°C is 5000 - 50000 mPa·s.

10. Application of the hyperbranched photocurable polyurethane acrylate resin prepared by the method according to any one of claims 1-8 or the hyperbranched photocurable polyurethane acrylate resin according to claim 9 in the fields of 3C coatings, wood coatings, nail polishes, and waterproof coatings.