Preparation method of light-cured polyurethane acrylate with high bio-based content

Abstract

The invention discloses a preparation method of light-cured polyurethane acrylate with high bio-based content, which comprises the following steps: reacting an acidic unsaturated monomer with glycidyl to obtain a dihydroxyl unsaturated monomer, and carrying out chain extension reaction on bio-based diisocyanate, the dihydroxyl unsaturated monomer and castor oil to obtain the light-cured polyurethane acrylate with high bio-based content. The light-cured polyurethane acrylate with high bio-based content is obtained. The bio-based content of the product reaches 70% or above, the product is light in color and luster, the performance of a cured film is basically equal to or better than that of conventional polyurethane acrylate, and the product is a green, environment-friendly and sustainable photocuring material.

Description

Technical Field

[0001] The invention belongs to the technical field of photocurable resins, and in particular relates to a method for preparing photocurable polyurethane acrylate with high bio-based content. Background Art

[0002] Modern petroleum-based chemical industry produces a large amount of basic raw materials for the production of essential industrial products such as plastics, rubber, coatings and adhesives. However, in the context of the global petrochemical energy crisis, reducing dependence on petrochemical resources has become a top priority.

[0003] In this context, choosing green, renewable, and low-carbon bio-based materials has become an inevitable choice. Bio-based materials are made from renewable biomass such as grains, legumes, straw, bamboo and wood powder, and are obtained through biotransformation to obtain biopolymer materials or monomers, which are then further polymerized to form polymer materials. Bio-based materials have the characteristics of green production, environmental friendliness, and resource conservation, and have become a rapidly growing emerging industry. Compared with traditional materials, bio-based materials effectively reduce carbon emissions in the production process and are the development direction of new materials in the future.

[0004] Chinese patent application No. 202111155910.3 discloses a method for preparing a bio-based photocurable resin based on isosorbide and its application: using isosorbide as an initiator, ring-opening ε-caprolactone to obtain isosorbide-based polyester polyol, and then reacting with an adduct of isophorone diisocyanate and hydroxy acrylate monomers to obtain an isosorbide-based bio-based photocurable resin. The isosorbide used in this route is a typical bio-based polyol. However, since isosorbide is only used as an initiator, the overall mass proportion of the final product is relatively small (about 5-15%), and most of the raw materials still come from traditional fossil energy sources, which is obviously not enough to promote the use of bio-based materials to replace fossil raw materials.

[0005] Chinese patent application No. 202110932030.6 discloses a fully bio-based UV-curable coating, which mainly uses tung oil-based lacquer phenol compounds, tung oil and epoxy castor oil with a composite photoinitiator. After ultraviolet irradiation, the crosslinking degree of the coating reaches more than 99.5% and the hardness reaches 6H. However, the color of the coating is darker and cannot be used in many fields with high color requirements. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to overcome the deficiencies in the prior art and provide a novel preparation method for preparing a photocurable polyurethane acrylate with a high bio-based content.

[0007] The invention discloses a method for preparing a photocurable polyurethane acrylate with a high bio-based content, wherein a carboxyl unsaturated monomer is reacted with glycidol to obtain a dihydroxy unsaturated monomer, and then a bio-based diisocyanate is used to carry out a chain extension reaction with the dihydroxy unsaturated monomer and castor oil to obtain a photocurable polyurethane acrylate with a high bio-based content. The bio-based content of the product reaches more than 70%, and the performance of the cured film of the resin is basically the same as or better than that of conventional polyurethane acrylate, and the photocurable material is green, environmentally friendly and sustainable.

[0008] Technical solution: In order to achieve the above invention objectives, the technical solution adopted by the present invention is:

[0009] A method for preparing a photocurable polyurethane acrylate with a high bio-based content comprises the following steps:

[0010] (1) a carboxyl unsaturated monomer undergoes a ring-opening reaction with glycidol to obtain a dihydroxy unsaturated monomer;

[0011] (2) 1,5-pentanediisocyanate reacts with dihydroxy unsaturated monomers and castor oil to produce a photocurable polyurethane acrylate with a high bio-based content.

[0012] As a preferred embodiment, in the above-mentioned method for preparing a photocurable polyurethane acrylate with a high bio-based content, the carboxyl unsaturated monomer in step (1) is selected from one or more of acrylic acid and methacrylic acid.

[0013] As a preferred embodiment, the above-mentioned method for preparing a photocurable polyurethane acrylate with a high bio-based content, the synthesis method of the dihydroxy unsaturated monomer in step (1) is: a carboxyl unsaturated monomer and glycidol are mixed in a molar ratio of 1:1.01 to 1:1.08, a certain amount of p-hydroxyanisole and tetrabutylammonium bromide are added, the temperature is slowly raised to 100 to 110°C for reaction until the acid value is ≤5mgKOH / g, and the temperature is lowered to discharge the material to obtain the dihydroxy unsaturated monomer. Wherein, p-hydroxyanisole accounts for 0.05 to 0.2% of the total mass of the reactants, and tetrabutylammonium bromide accounts for 0.5 to 1.5% of the total mass of the reactants.

[0014] As a preferred embodiment, in the method for preparing a photocurable polyurethane acrylate with a high bio-based content described above, the synthesis method of the photocurable polyurethane acrylate with a high bio-based content in step (2) is: 1,5-pentanediisocyanate, a dihydroxy unsaturated monomer and castor oil are mixed in a certain proportion, a certain amount of dibutyltin dilaurate and p-hydroxyanisole are added, and the mixture is slowly heated to 60-90° C. for reaction until the NCO content is ≤0.4%, and the mixture is cooled and discharged to obtain a photocurable polyurethane acrylate with a high bio-based content. Among them, the relationship between the molar amount of isocyanate functional groups a of 1,5-pentanediisocyanate, the molar amount of hydroxyl functional groups b of the dihydroxy unsaturated monomer and the molar amount of hydroxyl functional groups c of castor oil is: a:(b+c)=1:1.02~1:1.06, b:c=1:0.1~1:2; dibutyltin dilaurate DBTDL accounts for 0.01~0.08% of the total mass of the reactants, and p-hydroxyanisole accounts for 0.05~0.2% of the total mass of the reactants.

[0015] 1,5-Pentanediamine is mainly prepared by bioconversion and fermentation methods. It is a completely bio-based raw material. 1,5-Pentanediamine can be prepared into 1,5-pentanediisocyanate after phosgenation reaction, which can be used in the synthesis of polyurethane. Soybean oil can be prepared into oleic acid and glycerol after saponification; glycerol can be further condensed to prepare glycidol, which is a bio-based raw material. Castor oil is directly derived from vegetable oil and is a bio-based raw material.

[0016] The beneficial effects are:

[0017] The bio-based raw material of the preparation method of the present invention is a green, environmentally friendly, low-carbon raw material, and is an important choice for replacing fossil raw materials in the future. Some of the traditional bio-based light-curing resins have low bio-based component content and cannot replace fossil raw materials; some have dark colors and cannot be used in some high-end fields.

[0018] In order to overcome the above defects, the present invention has developed a photocurable polyurethane acrylate with high bio-based content. The unique creativity of the present invention is as follows: the present invention first reacts an acidic unsaturated monomer with glycidol to obtain a dihydroxy unsaturated monomer, and then uses a bio-based diisocyanate with the dihydroxy unsaturated monomer and castor oil for chain extension reaction to obtain a photocurable polyurethane acrylate with high bio-based content. Most of the raw materials selected by the present invention come from bio-based materials, among which the bio-based content of 1,5-pentane diisocyanate is 63.7%, and the bio-based content of glycidol and castor oil is 100%, so the bio-based content of the final product of the present invention can reach more than 70%.

[0019] The cured polyurethane acrylate synthesized by the present invention not only has a bio-based component content of more than 70% and a light color, but also has a structure that is basically consistent with conventional polyurethane acrylate derived from fossil energy. It is a green, environmentally friendly, and sustainable photocurable material, an alternative method for saving limited resources, and has important environmental value. DETAILED DESCRIPTION

[0020] Example 1

[0021] A method for preparing a photocurable polyurethane acrylate with a high bio-based content, comprising the following steps:

[0022] (1) 72.1 g of acrylic acid, 77.8 g of glycidol, 0.22 g of p-hydroxyanisole, and 1.2 g of tetrabutylammonium bromide were placed in a reaction flask, stirred, and slowly heated to 110° C. for reaction until the acid value dropped below 5 mgKOH / g, and then cooled to obtain a dihydroxy unsaturated monomer 1;

[0023] (2) 102.8 g of 1,5-pentanediisocyanate, 73.1 g of dihydroxy unsaturated monomer 1, 137.7 g of castor oil, 0.13 g of dibutyltin dilaurate, and 0.31 g of p-hydroxyanisole were placed in a reaction flask, stirred, and slowly heated to 75° C. for reaction until the NCO content dropped below 0.4%, thereby obtaining a photocurable polyurethane acrylate 1 with a high biobased content.

[0024] Example 2

[0025] A method for preparing a photocurable polyurethane acrylate with a high bio-based content, comprising the following steps:

[0026] (1) 86.1 g of methacrylic acid, 80 g of glycidol, 0.20 g of p-hydroxyanisole, and 1.66 g of tetrabutylammonium bromide were placed in a reaction flask, stirred, and slowly heated to 115° C. for reaction until the acid value dropped below 5 mgKOH / g, and then cooled to obtain a dihydroxy unsaturated monomer 2;

[0027] (2) 95.44 g of 1,5-pentanediisocyanate, 80.1 g of dihydroxy unsaturated monomer 2, 103.25 g of castor oil, 0.14 g of dibutyltin dilaurate, and 0.59 g of p-hydroxyanisole were placed in a reaction flask, stirred, and slowly heated to 75° C. for reaction until the NCO content dropped below 0.4%, thereby obtaining a photocurable polyurethane acrylate 2 with a high biobased content.

[0028] Example 3

[0029] A method for preparing a photocurable polyurethane acrylate with a high bio-based content comprises the following steps:

[0030] (1) 72.1 g of acrylic acid, 77.8 g of glycidol, 0.24 g of p-hydroxyanisole, and 1.50 g of tetrabutylammonium bromide were placed in a reaction flask, stirred, and slowly heated to 110° C. for reaction until the acid value dropped below 5 mgKOH / g, and then cooled to obtain a dihydroxy unsaturated monomer 3;

[0031] (2) 132.15 g of 1,5-pentanediisocyanate, 73.1 g of dihydroxy unsaturated monomer 3, 275.34 g of castor oil, 0.38 g of dibutyltin dilaurate, and 0.72 g of p-hydroxyanisole were placed in a reaction flask, stirred, and slowly heated to 75° C. for reaction until the NCO content dropped below 0.4%, thereby obtaining a photocurable polyurethane acrylate 3 with a high biobased content.

[0032] Example 4 Performance Test Example

[0033] Aliphatic polyurethane acrylate SM6202 (produced by Jiangsu Sanmu Chemical Co., Ltd.), 1,6-hexanediol diacrylate (HDDA, produced by Jiangsu Sanmu Chemical Co., Ltd.), and photoinitiator 1173 (produced by Jiangsu Sanmu Chemical Co., Ltd.) were prepared according to the formula in Table 1 to obtain a light-curing varnish.

[0034] Table 1 Light-curing varnish formulation

[0035]

[0036]

[0037] Take the varnish sample prepared in Table 1, and use a wire rod to coat it on a glass plate to obtain a coating with a thickness of about 25 microns. Then irradiate it with a mercury lamp light source, and measure the number of machine passes to achieve surface dryness, the hardness and flexibility of the cured film, etc. The results are shown in Table 2.

[0038] Table 2 Comparison of properties of light-cured varnish films

[0039]

[0041] The hardness is tested according to the method described in the national standard GB / T 6739-2006 "Determination of paint film hardness by pencil method for paints and varnishes".

[0042] The flexibility is tested according to the method described in the national standard GB / T 1731-1993 "Determination of paint film flexibility".

[0043] The gloss is tested according to the method described in the national standard GB / T 9754-2007 "Determination of 20°, 60° and 85° specular gloss of paints and varnishes without metallic pigments".

[0044] The above experimental results show that the photocurable polyurethane acrylate with high bio-based content prepared by the method of the present invention has a bio-based component of more than 70%, a lighter color (≤50APHA), and the basic properties of the cured film are very close to those of the commercial polyurethane acrylate SM6202, or even slightly better. In addition, by comparing Examples 1 to 3, Example 1 has the best performance in all aspects.

Claims

1. A method for preparing a photocurable polyurethane acrylate with a high bio-based content, characterized in that: The following steps are involved: (1) a carboxyl unsaturated monomer undergoes a ring-opening reaction with glycidol to obtain a dihydroxy unsaturated monomer; (2) 1,5-pentanediisocyanate reacts with dihydroxy unsaturated monomers and castor oil to produce a photocurable polyurethane acrylate with a high bio-based content.

2. The method for preparing a photocurable polyurethane acrylate with a high bio-based content according to claim 1, characterized in that: The carboxyl unsaturated monomer in step (1) is selected from one or more of acrylic acid and methacrylic acid.

3. The method for preparing a photocurable polyurethane acrylate with a high bio-based content according to claim 1, characterized in that: The synthesis method of the dihydroxy unsaturated monomer in step (1) is as follows: a carboxyl unsaturated monomer and glycidol are mixed in a molar ratio of 1:1.01 to 1:1.08, a certain amount of p-hydroxyanisole and tetrabutylammonium bromide are added, the temperature is slowly raised to 100 to 110° C. for reaction until the acid value is ≤5 mgKOH / g, the temperature is lowered and the material is discharged to obtain the dihydroxy unsaturated monomer.

4. The method for preparing a photocurable polyurethane acrylate with a high bio-based content according to claim 3, characterized in that: The p-hydroxyanisole accounts for 0.05-0.2% of the total mass of the reactants, and the tetrabutylammonium bromide accounts for 0.5-1.5% of the total mass of the reactants.

5. The method for preparing a photocurable polyurethane acrylate with high bio-based content according to claim 1, characterized in that: The synthesis method of the photocurable polyurethane acrylate with high bio-based content in step (2) is as follows: 1,5-pentanediisocyanate, a dihydroxy unsaturated monomer and castor oil are mixed in a certain proportion, a certain amount of dibutyltin dilaurate and p-hydroxyanisole are added, and the mixture is slowly heated to 60-90° C. for reaction until the NCO content is ≤0.4%, and the mixture is cooled and discharged to obtain the photocurable polyurethane acrylate with high bio-based content.

6. The method for preparing a photocurable polyurethane acrylate with high bio-based content according to claim 5, characterized in that: in, The relationship among the molar weight a of the isocyanate functional group of 1,5-pentanediisocyanate, the molar weight b of the hydroxyl functional group of the dihydroxy unsaturated monomer and the molar weight c of the hydroxyl functional group of castor oil is: a:(b+c)=1:1.02~1:1.06, b:c=1:0.1~1:

2.

7. The method for preparing a photocurable polyurethane acrylate with a high bio-based content according to claim 5, characterized in that: in, The dibutyltin dilaurate DBTDL accounts for 0.01-0.08% of the total mass of the reactants, and the p-hydroxyanisole accounts for 0.05-0.2% of the total mass of the reactants.

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