Anti-oxidation polymerization inhibition UV photocuring urethane monomer and preparation method thereof

Abstract

The invention relates to the technical field of photocuring monomers, in particular to an anti-oxidation polymerization inhibition UV (ultraviolet) photocuring urethane type monomer, which is prepared from the following components in parts by mass: 1 part of hydroxyl-containing monomer, 1 to 3 parts of terminated monomer, 1 to 3 parts of diisocyanate, 300ppm of polymerization inhibitor and 300ppm of catalyst, the monomer containing the hydroxyl is oxygen heterocyclic ketone containing the hydroxyl or oxazolidinone containing the hydroxyl; the preparation method comprises the following steps: adding a catalyst and a polymerization inhibitor into diisocyanate, uniformly mixing, controlling the reaction temperature not to exceed 45 DEG C, dropwise adding an end-capping monomer, titrating to monitor the reaction, and finishing the first-stage reaction when the NCO reaction amount reaches 50-55% of the initial numerical value; and adding a hydroxyl-containing monomer into the reaction liquid in the first stage, and finishing the reaction when the content of NCO in the system is monitored to be less than 0.1%. According to the preparation method disclosed by the invention, oxygen heterocyclic ketone or an alcohol substance containing oxazolidinone is subjected to ring-opening reaction in a photocuring process to serve as an active H donor to quickly react with peroxy free radicals, so that active free radicals are effectively regenerated, and anti-oxygen polymerization inhibition is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of photocurable monomers, and in particular to an antioxidant and polymerization-inhibited UV photocurable urethane monomer and a preparation method thereof. Background Art

[0002] Polyurethane acrylate is one of the most commonly used photocurable raw materials in industry, often used in coatings, inks, 3D printing, and other fields. Its composition varies, and different raw materials and proportions can produce different effects. It is the most widely used type of photocurable material. However, because polyurethane acrylate often polymerizes via free radical polymerization during UV light curing, it is significantly affected by oxygen inhibition. This leads to slow curing speeds that affect production efficiency, low surface curing degrees that affect performance, and the need for large amounts of expensive initiators, which increase costs.

[0003] There are several methods to combat oxygen inhibition:

[0004] (1) Changing the environment, such as nitrogen ventilation and increasing light intensity, but this requires high equipment;

[0005] (2) Increasing the amount of initiator used will increase costs and affect performance;

[0006] (3) Adding tertiary amine additives will cause the polymer to turn yellow and easily undergo Michael addition reaction, resulting in a decrease in double bond density;

[0007] (4) Other methods such as using thiols and cationic polymerization raw materials have disadvantages such as high cost and affecting polymer properties. Summary of the Invention

[0008] The present invention solves the problems in the related art and proposes an antioxidant and polymerization-inhibiting UV light-curing urethane monomer and a preparation method thereof. The monomer is modified with an oxocyclic ketone or an alcohol containing oxazolidinone. Both of these substances can undergo a ring-opening reaction during the light-curing process, showing a unique ring structure change. Therefore, they can act as active H donors, can quickly react with peroxyl radicals, and effectively regenerate active free radicals, thereby exerting an excellent antioxidant and polymerization-inhibiting effect.

[0009] In order to solve the above technical problems, the present invention is achieved through the following technical solution: an antioxidant and polymerization-inhibiting UV light-curing urethane monomer, which, by mass fraction, includes 1 part of a hydroxyl-containing monomer, 1 to 3 parts of a blocking monomer, 1 to 3 parts of a diisocyanate, 300 ppm of an inhibitor and 300 ppm of a catalyst; the hydroxyl-containing monomer is a hydroxyl-containing oxacyclic ketone or a hydroxyl-containing oxazolidinone.

[0010] As a preferred embodiment, the end-capping monomer is at least one of hydroxyethyl acrylate, pentaerythritol triacrylate, p-hydroxystyrene, and tert-butylaminoethyl methacrylate.

[0011] As a preferred embodiment, the diisocyanate is at least one of dicyclohexylmethyl diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and ditolyl diisocyanate.

[0012] As a preferred embodiment, the polymerization inhibitor is at least one of p-hydroxyanisole, tert-butylcatechol, and hydroquinone.

[0013] As a preferred embodiment, the catalyst is at least one of dibutyltin dilaurate, organic bismuth, lithium salt, and n-butyl lead ester.

[0014] As a preferred embodiment, the hydroxyl-containing monomer is any one of hydroxymethyldioxolane or 3-(2-hydroxyethyl)-2-oxazolidinone, and its structural formula is as follows:

[0015] (hydroxymethyldioxolane), (3-(2-hydroxyethyl)-2-oxazolidinone).

[0016] On the other hand, the present inventors also provide a method for preparing an antioxidant-inhibited UV-curable urethane monomer, comprising the following steps:

[0017] S1. Preparation of raw materials: prepare monomer raw materials according to the amount in claim 1;

[0018] S2, first stage reaction: adding the catalyst and the polymerization inhibitor to the diisocyanate and stirring and mixing thoroughly, controlling the reaction temperature not to exceed 45° C., slowly adding the end-capping monomer dropwise, and monitoring the reaction by titration. The first stage reaction is completed when the NCO reaction amount reaches 50% to 55% of its initial value;

[0019] S3, second stage reaction: slowly add the hydroxyl-containing monomer to the reaction solution of the first stage. When the NCO content in the monitoring system is less than 0.1%, the final reaction is completed to obtain an antioxidant and inhibited UV light-curing urethane monomer.

[0020] As a preferred embodiment, the temperature of the second stage reaction is 60-70°C.

[0021] In addition, since water reacts easily with isocyanate, a small amount of water can consume a large amount of isocyanate, and the water content of all raw materials should be less than 1000ppm.

[0022] Compared with the prior art, the present invention has the following beneficial effects: the present invention uses oxygen heterocyclic ketones or alcohols containing oxazolidinone for modification. Both types of substances can undergo ring-opening reactions during the photocuring process, showing unique ring structure changes. Therefore, they can serve as active H donors, can quickly react with peroxyl radicals, effectively regenerate active free radicals, and thus exert excellent antioxidant and polymerization inhibition effects; the preparation method of the present application is simple and highly operable, and can produce antioxidant and polymerization-inhibited UV photocurable urethane monomers that meet performance requirements; compared with traditional acrylic monomers (including polyurethanes), the UV photocurable polyurethane monomers obtained by the present invention have significant antioxidant and polymerization inhibition capabilities, significantly accelerated curing speed, and solved the problems of incomplete curing caused by oxygen inhibition, and are low in cost. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] The first aspect of the present invention provides an antioxidant and polymerization-inhibiting UV light-curing urethane monomer, which comprises, by mass fraction, 1 part of a hydroxyl-containing monomer, 1 to 3 parts of a blocking monomer, 1 to 3 parts of a diisocyanate, 300 ppm of an inhibitor, and 300 ppm of a catalyst; the hydroxyl-containing monomer is a hydroxyl-containing oxacyclic ketone or a hydroxyl-containing oxazolidinone.

[0026] In one embodiment, the end-capping monomer is at least one of hydroxyethyl acrylate, pentaerythritol triacrylate, p-hydroxystyrene, and tert-butylaminoethyl methacrylate.

[0027] In one embodiment, the diisocyanate is at least one of dicyclohexylmethyl diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and ditolyl diisocyanate.

[0028] In one embodiment, the polymerization inhibitor is at least one of p-hydroxyanisole, tert-butylcatechol, and hydroquinone.

[0029] In one embodiment, the catalyst is at least one of dibutyltin dilaurate, organic bismuth, lithium salt, and n-butyl lead ester.

[0030] In one embodiment, the hydroxyl-containing monomer is any one of hydroxymethyldioxolane or 3-(2-hydroxyethyl)-2-oxazolidinone, and the structural formula thereof is as follows:

[0031] (hydroxymethyldioxolane), (3-(2-hydroxyethyl)-2-oxazolidinone).

[0032] Since water reacts easily with isocyanate, a small amount of water can consume a large amount of isocyanate, and the water content of all raw materials should be less than 1000ppm.

[0033] The second aspect of the present invention further provides a method for preparing an antioxidant-inhibited UV-curable urethane monomer, the specific steps of which are as follows:

[0034] S1. 1 equivalent of diisocyanate was added to the reaction flask, and 500ppm of polymerization inhibitor and 500ppm of catalyst were added and stirred;

[0035] S2. 1.05 equivalents of a capping agent was added dropwise to the reaction system and the reaction temperature was controlled to rise no more than 5°C. The reaction was stirred at room temperature until the NCO content in the reaction solution was determined by titration with di-n-butylamine to be about 50% of its initial value. The reaction was stopped to obtain a one-end capped NCO intermediate.

[0036] S3. Add a hydroxyl-containing monomer to the intermediate reaction solution obtained in 2 and heat to 60-70°C with stirring. When the NCO content in the titration system is less than 0.1%, the antioxidant and inhibited UV light-curable urethane monomer is obtained.

[0037] Example 1:

[0038] Step 1: IPDI (10 g, 0.0449 mol, 1 eq), p-hydroxyanisole (0.005 g, 500 ppm) and dibutyltin dilaurate (0.005 g, 500 ppm) were put into a reaction flask and stirred evenly. The temperature was controlled not to exceed 45 ° C. Hydroxyethyl acrylate (5.49 g, 0.0472 mol, 1.05 eq) was added dropwise to IPDI. After stirring at room temperature for 1 hour, the NCO content was titrated with di-n-butylamine titration to obtain 11.8%. The first stage reaction was completed;

[0039] Step 2: Add 5.3 g (0.045 mol, 1 eq) of hydroxymethyldioxolane to the reaction solution obtained in step 1, and heat to 60° C. for reaction for 2 hours. The NCO content of the titration reaction is 0%, thereby obtaining an antioxidant-inhibited UV-curable urethane monomer A.

[0040] Example 2:

[0041] TDI (10 g, 0.0574 mol, 1 eq), p-hydroxyanisole (0.005 g, 500 ppm), and dibutyltin dilaurate (0.005 g, 500 ppm) were put into a reaction flask and stirred evenly. The temperature was controlled not to exceed 45° C. Hydroxyethyl acrylate (7.00 g, 0.0602 mol, 1.05 eq) was added dropwise to TDI. After stirring at room temperature for 1 h, the mixture was titrated with di-n-butylamine to obtain an NCO content of 14.8%. The first stage reaction was completed.

[0042] Step 2: Add 6.77 g (0.0574 mol, 1 eq) of hydroxymethyldioxolane to the reaction solution obtained in Step 1, and heat to 60°C for 2 hours. Titration results in an NCO content of 0%, thereby obtaining an antioxidant, inhibited, UV-curable urethane monomer B.

[0043] Example 3:

[0044] Step 1: IPDI (10 g, 0.0449 mol, 1 eq), p-hydroxyanisole (0.005 g, 500 ppm) and dibutyltin dilaurate (0.005 g, 500 ppm) were put into a reaction flask and stirred evenly. The temperature was controlled not to exceed 45 ° C. Hydroxyethyl acrylate g (5.49 g, 0.0472 mol, 1.05 eq) was added dropwise to IPDI. After stirring at room temperature for 1 hour, the NCO content was titrated with di-n-butylamine titration to obtain 11.8%. The first stage reaction was completed;

[0045] Step 2: Add 5.81 g (0.045 mol, 1 eq) of 3-(2-hydroxyethyl)-2-oxazolidinone to the reaction solution obtained in step 1, and heat to 60° C. for reaction for 2 hours. The NCO content of the reaction is titrated to 0%, thereby obtaining an antioxidant-inhibited UV-curable urethane monomer C.

[0046] Example 4:

[0047] TDI (10 g, 0.0574 mol, 1 eq), p-hydroxyanisole (0.005 g, 500 ppm) and dibutyltin dilaurate (0.005 g, 500 ppm) were put into a reaction flask and stirred evenly. Hydroxyethyl acrylate (7.00 g, 0.0602 mol, 1.05 eq) was added dropwise to TDI under temperature control. After stirring at room temperature for 1 h, the NCO content was titrated with di-n-butylamine titration to obtain 14.8%. The first stage reaction was completed.

[0048] Step 2: Add 7.42 g (0.0574 mol, 1 eq) of hydroxymethyldioxolane to the reaction solution obtained in step 1, and heat to 70° C. for 2 hours. Titration results in an NCO content of 0%, thereby obtaining an antioxidant-inhibited UV-curable urethane monomer D.

[0049] The antioxidant and polymerization-inhibiting UV light-curing urethane monomer provided by the present invention also requires the addition of a photoinitiator, including photoinitiator 1173 and photoinitiator 184, during photopolymerization. Taking photoinitiator 1173 as an example, the weight ratio of the antioxidant and polymerization-inhibiting UV light-curing urethane monomer provided by the present invention to the photoinitiator is 100:(0.5-2). That is, 0.5 to 2 parts of photoinitiator 1173 are added to 100 parts of the antioxidant and polymerization-inhibiting UV light-curing urethane monomer provided by the present invention, stirred evenly, and then applied to a galvanized sheet and rolled evenly with a 20μm wire rod. After the sheet is leveled, it is cured by irradiation with an electrodeless lamp.

[0050] Example 5:

[0051] Step 1: Monomer A is prepared into curing raw materials containing 0.5%, 1%, and 2% of photoinitiator 1173 respectively; monomer B is prepared into curing raw materials containing 0.5%, 1%, and 2% of photoinitiator 1173 respectively; monomer C is prepared into curing raw materials containing 0.5%, 1%, and 2% of photoinitiator 1173 respectively; monomer D is prepared into curing raw materials containing 0.5%, 1%, and 2% of photoinitiator 1173 respectively; TPGDA is prepared into curing raw materials containing 0.5%, 1%, and 2% of photoinitiator 1173 respectively.

[0052] Step 2: Apply the light-curing material prepared in Step 1 to the galvanized sheet and evenly apply it with a 20μm wire rod. Once leveled, use an electrodeless lamp to cure. Adjust the track speed during curing to determine the curing speed and antioxidant and polymerization inhibition capabilities. The electrodeless lamp used is a TB150GS from Dahua Bluelight (Beijing) Technology Co., Ltd., with an output of 80W / cm, a tube length of 15cm (6 inches), and a track length of 55cm.

[0053] Table 1 Monomer and TPGDA curing speed in the examples of the present invention

[0054] Photoinitiator content 0.5％ 1％ 2％ Photocurable urethane monomer \ \ \ \ A \ <1m / min 5m / min 24m / min B \ <1m / min 5m / min 24m / min C \ 5m / min 24m / min 24m / min D \ 5m / min 24m / min 24m / min TPGDA \ <1m / min <1m / min 1m / min

[0055] As shown in Table 1, when completely dry under the same conditions, the antioxidant photocurable urethane monomer provided by the present invention has a faster curing speed and extremely high antioxidant capacity while requiring less photoinitiator.

[0056] Example 6:

[0057] Step 1: Monomer A is diluted with TPGDA to form photocurable raw materials with solid contents of 30%, 50%, and 70%, and 2% of photoinitiator 1173 is added; monomer B is diluted with TPGDA to form photocurable raw materials with solid contents of 30%, 50%, and 70%, and 2% of photoinitiator 1173 is added; monomer C is diluted with TPGDA to form photocurable raw materials with solid contents of 30%, 50%, and 70%, and 2% of photoinitiator 1173 is added; monomer D is diluted with TPGDA to form photocurable raw materials with solid contents of 30%, 50%, and 70%, and 2% of photoinitiator 1173 is added.

[0058] Step 2: Apply the light-curing raw materials prepared in Step 1 to the galvanized sheet respectively, and roll it evenly with a 20-micron wire rod. After it is leveled, use an electrodeless lamp to cure it. During curing, adjust the moving speed of the crawler to determine its curing speed and antioxidant and polymerization inhibition ability. The electrodeless lamp used is TB150GS from Dahua Blu-ray (Beijing) Technology Co., Ltd., with an output power of 80W / cm, a lamp tube length of 15cm (6 inches), and a crawler length of 55cm.

[0059] Table 2 Curing speed of the monomers of the present invention with different contents of TPGDA added

[0060]

[0061] As shown in Table 2, after adding the antioxidant and polymerization-inhibiting photocurable urethane monomer provided by the present invention, the curing speed of TPGDA is significantly accelerated and the antioxidant and polymerization-inhibiting ability is significantly improved.

[0062] The above are preferred embodiments of the present invention. Those skilled in the art to which the present invention belongs can also change and modify the above embodiments. Therefore, the present invention is not limited to the above specific embodiments. Any obvious improvements, replacements or modifications made by those skilled in the art on the basis of the present invention fall within the scope of protection of the present invention.

Claims

1. An antioxidant, inhibited UV light-curing urethane monomer, characterized in that: Calculated by mass, it includes 1 part of a hydroxyl-containing monomer, 1 to 3 parts of a blocking monomer, 1 to 3 parts of a diisocyanate, 300 ppm of a polymerization inhibitor and 300 ppm of a catalyst; the hydroxyl-containing monomer is a hydroxyl-containing oxacyclic ketone or a hydroxyl-containing oxazolidinone.

2. The antioxidant, inhibited UV light-curing urethane monomer according to claim 1, characterized in that: The end-capping monomer is at least one of hydroxyethyl acrylate, pentaerythritol triacrylate, p-hydroxystyrene, and tert-butylaminoethyl methacrylate.

3. The antioxidant and polymerization-inhibited UV light-curing urethane monomer according to claim 1, characterized in that: The diisocyanate is at least one of dicyclohexylmethyl diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and ditolyl diisocyanate.

4. The antioxidant and polymerization-inhibited UV light-curing urethane monomer according to claim 1, characterized in that: The polymerization inhibitor is at least one of p-hydroxyanisole, tert-butylcatechol and hydroquinone.

5. The antioxidant and polymerization-inhibited UV light-curing urethane monomer according to claim 1, characterized in that: The catalyst is at least one of dibutyltin dilaurate, organic bismuth, lithium salt, and n-butyl lead ester.

6. The antioxidant, inhibited UV light-curing urethane monomer according to claim 1, characterized in that: The hydroxyl-containing monomer is any one of hydroxymethyldioxolane or 3-(2-hydroxyethyl)-2-oxazolidinone.

7. A method for preparing an antioxidant-inhibited UV-curable urethane monomer, characterized in that: Here are the steps: S1. Preparation of raw materials: prepare monomer raw materials according to the amount in claim 1; S2, first stage reaction: adding the catalyst and the polymerization inhibitor to the diisocyanate and stirring and mixing thoroughly, controlling the reaction temperature not to exceed 45° C., slowly adding the end-capping monomer dropwise, and monitoring the reaction by titration. When the NCO reaction amount reaches 50% to 55% of its initial value, the first stage reaction is completed; S3, second stage reaction: slowly add the hydroxyl-containing monomer to the reaction solution of the first stage. When the NCO content in the monitoring system is less than 0.1%, the final reaction is completed to obtain an antioxidant and inhibited UV light-curing urethane monomer.

8. The method for preparing the antioxidant and inhibited UV light-curing urethane monomer according to claim 6, characterized in that: The temperature of the second stage reaction is 60-70°C.

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