CN105001177B - A kind of triarylsulfonium salt containing benzoxazoles skeleton and preparation method thereof - Google Patents

Abstract

The present invention relates to a kind of aromatic sulfonium salt compound, triarylsulfonium salt specifically related to containing benzoxazoles skeleton and its preparation method and application, the method is by 2 mercaptobenzoxazoles and 1,4 diiodo-benzenes, after C S key coupling reaction synthesis of phenyl double thioether compounds are carried out under microwave, then it is prepared from the reaction of high salt compounded of iodine；The UV absorption wave-length coverage of such compound widen can red shift to more than 290nm, in ultraviolet-curing paint, can as cation light initiator be used for compositions of ultraviolet curing type, show good surface cure ability and dissolubility.

Description

A kind of triaryl sulfonium salt containing benzoxazole skeleton and preparation method thereof

technical field

The present invention relates to a triaryl sulfonium salt, specifically a triaryl sulfonium salt containing a benzoxazole skeleton and a disulfide atom and a preparation method thereof, and the salt is used as a photoinitiator in an ultraviolet light curing composition, especially an ultraviolet light curing composition. application in cured coatings.

Background technique

As a green technology, UV curing technology is widely used in coatings, inks, electronics, biology and other fields. The UV curing system is mainly composed of resin, monomer, photoinitiator and auxiliary agent. Among them, the photoinitiator is the key component, which generates active free radicals or cations after absorbing ultraviolet light, and initiates rapid polymerization and curing of the resin to form a film. Compared with the free radical type, the cationic photoinitiator has a smaller shrinkage rate of the coating after curing, and better adhesion and other properties. As a commonly used cationic initiator, calcite salts have the disadvantages of low solubility and the formation of small odorous molecules (such as benzene and diphenyl sulfide) due to C-S bond breakage during curing radiation. Therefore, the development of a new type of columium salt photoinitiator, which has the advantages of excellent solubility, low mobility, and small benzene release, has aroused the interest of many scholars.

Contents of the invention

The object of the present invention is to provide a kind of triaryl sulfonium salt containing benzoxazole skeleton, disulfide atom and preparation method thereof, and this salt is used as photoinitiator, in ultraviolet light curing composition especially ultraviolet light curing coating application. As a photoinitiator, the sulfonium salt has the characteristics of low odor, low mobility and fast curing speed.

A kind of triaryl sulfonium salt containing benzoxazole skeleton provided by the present invention, its structural formula is:

A kind of preparation method containing the triaryl sulfonium salt of benzoxazole skeleton provided by the invention comprises the following steps:

1) Add 2-mercaptobenzoxazole and 1,4-diiodobenzene into a long-necked round bottom flask, dissolve with N,N-dimethylformamide (DMF), then add cuprous iodide, hydroxide Potassium; put the long-necked round-bottom flask into a microwave reactor, set the power to 20-40W, and the reaction time is 15-25min, transfer the reaction solution to a separatory funnel, extract with ethyl acetate and wash with brine, and remove by rotary evaporation solvent, and separated by column chromatography to obtain a light yellow solid product 1,4-bis(2-benzoxazolylsulfanyl)benzene compound (I).

2) Add the product obtained in step (1) and diaryl iodide trifluoromethanesulfonate into a round-bottomed flask, dissolve it with 1,1,2,2-tetrachloroethane, then add cuprous iodide, and heat up to After reacting at 110°C for 2 hours, the reaction solution was transferred to a separatory funnel, extracted with ethyl acetate and washed with brine, the solvent was removed by rotary evaporation, and separated by column chromatography to obtain a light yellow solid product triarylsulfonium salt (II).

The molar ratio of 2-mercaptobenzoxazole, 1,4-diiodobenzene, cuprous iodide and potassium hydroxide in the step (1) is 1:0.5:0.05:2.

The molar ratio of compound (I), diaryl iodide trifluoromethanesulfonate and cuprous iodide in the step (2) is 1:2.4:0.1.

The N,N-dimethylformamide in the step (1) is replaced by a mixed solvent of ethanol and N,N-dimethylformamide.

The microwave power in the step (1) is preferably 30W, and the reaction time is 20min.

The diaryl iodide triflate is diphenyl iodide triflate or bis-(4-tolyl) iodine triflate.

The invention uses a triarylsulfonium salt containing a benzoxazole skeleton and a disulfide atom as a photoinitiator in an ultraviolet light curing composition, especially an ultraviolet light curing coating.

A photocurable composition provided by the present invention contains a triarylsulfonium salt with the above structure containing a benzoxazole skeleton and a disulfide atom.

Compared with prior art, the beneficial effect of the present invention:

The present invention introduces the benzoxazole skeleton into the molecule, and synthesizes a novel cationic triarylsulfonium salt with a high degree of conjugation, a maximum ultraviolet absorption above 290nm, a benzoxazole skeleton and a disulfide atom by a simple and efficient method .

In the present invention, the triarylsulfonium salt containing benzoxazole skeleton and disulfide atom is applied to the photocurable composition, which not only has good reactivity, surface curing ability and solubility, but also has oxazole group in the molecule, The high degree of molecular conjugation effectively increases the range of ultraviolet absorption, improves the light utilization rate and initiation efficiency, and reduces the release of benzene.

Description of drawings

Figure 1 Proton NMR spectrum of compound (I)

Figure 2 Proton NMR spectrum of compound (II-a)

Figure 3 Proton NMR spectrum of compound (II-b)

The ultraviolet absorption spectrum of Fig. 4 compound (II-b) and photoinitiator 184

detailed description

Example 1:

In a 100mL long-necked round bottom flask, add 2-mercaptobenzoxazole (2mmol), 1,4-diiodobenzene (1mmol) successively, dissolve with DMF (4mL), and then add cuprous iodide (0.1mmol) , and finally potassium hydroxide (4 mmol) was added. Put the flask into a microwave reactor, set the power to 30W, and react for 20min. The reaction solution was transferred to a separatory funnel, extracted with ethyl acetate and washed with brine, then the organic phase was dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation, followed by column chromatography to obtain the product 1,4-bis(benzene and oxazol-2-thio)benzene, compound (I).

Compound (I): white crystal, mp125-128°C, yield 75.8%. ¹ H NMR (CDCl ₃ , 300MHz) δ: 7.25-7.46 (m, ArH, 9H), 7.72-7.84 (m, ArH, 3H).

Example 2:

In a 50mL single-neck round bottom flask equipped with a stirring bar, the compound 1,4-bis(benzoxazol-2-thio)benzene (1mmol), diphenyliodotrifluoromethanesulfonate (2.4 mmol), dissolved in 1,1,2,2-tetrachloroethane (2 mL), and finally added cuprous iodide (0.1 mmol), stirred evenly, and reacted in an oil bath at 110° C. for 2 h. The reaction solution was transferred to a separatory funnel, extracted with ethyl acetate and washed with brine, then the organic phase was dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation, followed by column chromatography, and the mixture was sequentially washed with dichloromethane, ethyl acetate The ester was used as the eluent for column chromatography to obtain compound (II-a) as white crystals.

Compound (II-a): white crystal, mp 202-205°C, yield 66.7%. ¹ HNMR (CDCl ₃ , 300MHz) δ: 7.28-7.30(m, ArH, 3H), 7.44-7.46(m, ArH, 2H), 7.63-7.64(m, ArH, 2H), 7.77(m, ArH, 4H ).

Example 3:

In a 50mL single-necked round bottom flask equipped with a stirring bar, the compound 1,4-bis(benzoxazol-2-thio)benzene (1mmol), bis-(4-methylphenyl)iodotrifluoromethane were sequentially added The sulfonate (2.4 mmol) was dissolved in 1,1,2,2-tetrachloroethane (2 mL) and finally copper iodide (0.1 mmol) was added. After stirring evenly, react in an oil bath at 110°C for 2h. The reaction solution was transferred to a separatory funnel, extracted with ethyl acetate and washed with brine, then the organic phase was dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation, followed by column chromatography, and the mixture was sequentially washed with dichloromethane, ethyl acetate The ester was used as the eluent for column chromatography to obtain compound (II-b) as white crystals.

Compound (II-b): white crystals, mp 167-169°C, yield 76.1%. ¹ H NMR(CDCl ₃ ,300MHz)δ:2.43(s,CH ₃ ,3H),7.04-7.05(m,ArH,2H),7.15-7.17(m,ArH,3H),7.26-7.7.27(m ,ArH,2H),7.34-7.35(m,ArH,4H),7.42-7.43(m,ArH,4H).

The following examples are the curing performance of compound (II-a) or compound (II-b) of the present invention as a cationic photoinitiator and the comparison with the curing performance of commercially available free radical photoinitiator 184: the oligomer used wherein The substance is epoxy acrylate (UV1005-65 Zhongshan Qianfeng Chemical Factory); the monomer is 1,6-hexanediol diacrylate (produced by HDDA Zhongshan Qianfeng Chemical Factory); 1-hydroxycyclohexylphenylmethanol Ketone (184 Beijing Yingli Technology Company).

Embodiment 4: the application performance evaluation of compound (II-a)

Experimental formula:

working conditions

Under the condition of avoiding light, add 0.03g of photoinitiator, 0.5g of epoxy acrylate UV1005-650.5g, 0.45g of HDDA, and 0.02g of triethanolamine into the glass container, and stir evenly until the coating liquid becomes transparent. The mixture was coated on a glass plate with an applicator to form a film, the film thickness was 100um, and it was irradiated and cured in a medium-pressure mercury lamp, and the power of the mercury lamp was 400W.

Embodiment 5: the application performance evaluation of benzene compound (II-b)

Experimental formula:

Working condition is the same as embodiment 4

Embodiment 6 (comparative example): the application performance evaluation of photoinitiator 184

Experimental formula:

Working condition is the same as embodiment 4

Carry out performance test to the coating film of above-mentioned embodiment 4-6 composition:

a Surface dry time test: refers to dry method or cotton ball method.

b Hardness test: Pencil hardness test according to GB/T6739-1996. Use a coating film pencil scratch hardness tester to observe the scratch marks on the paint film, and take the pencil without scratches as the pencil hardness of the coating film.

c Adhesion test: cross-hatch method determination (refer to GB 9286-88). The adhesion of the coating film was judged by the cross-hatch test method. According to the degree of damage, it can be divided into 6 grades from 0 to 5. The best grade is 0, no small cells on the membrane surface have fallen off, and grade 5 is extremely poor, and the membrane surface has severely peeled off.

The evaluation results are shown in Table 1.

The application performance of compound (II-a), (II-b), (184) of table 1

As can be seen from the above table, triarylsulfonium salts containing benzoxazole skeletons and disulfide atoms can be used as photoinitiators to cure and form films, and the curing time of compound (II) is shorter; the hardness is higher than that of the existing photoinitiators 184 .

Claims (9)

1. a triaryl sulfonium salt containing a benzoxazole skeleton, characterized in that the structural formula is: 2. a kind of preparation method containing the triaryl sulfonium salt of benzoxazole skeleton as claimed in claim 1, is characterized in that, comprises the steps: 1) Add 2-mercaptobenzoxazole and 1,4-diiodobenzene into a long-necked round bottom flask, dissolve with N,N-dimethylformamide (DMF), then add cuprous iodide, hydroxide Potassium; put the long-necked round-bottom flask into a microwave reactor, set the power to 20-40W, and the reaction time is 15-25min, transfer the reaction solution to a separatory funnel, extract with ethyl acetate and wash with brine, then the organic phase Dry over anhydrous sodium sulfate, filter, and concentrate to obtain a brown liquid. After separation by column chromatography, 1,4-bis(2-benzoxazolylsulfanyl)benzene is obtained as a light yellow solid product; 2) Add the product 1,4-bis(2-benzoxazolylthio)benzene and diaryl iodide trifluoromethanesulfonate obtained in step 1) into a round bottom flask, and use 1,1,2,2- Add cuprous iodide after tetrachloroethane dissolves, heat up to 110°C for 2 hours, transfer the reaction solution to a separatory funnel, extract with ethyl acetate and wash with brine, then dry the organic phase with anhydrous sodium sulfate and filter , concentrated to obtain a brown liquid, and after separation by column chromatography, a light yellow solid product triarylsulfonium salt was obtained. 3. preparation method as claimed in claim 2 is characterized in that, the mol ratio of 2-mercaptobenzoxazole, 1,4-diiodobenzene, cuprous iodide and potassium hydroxide in described step 1) It is 1:0.5:0.05:2. 4. preparation method as claimed in claim 2 is characterized in that, described step 2) in 1,4-two (2-benzoxazolylsulfanyl) benzene, diaryl iodide trifluoromethanesulfonate , The molar ratio of cuprous iodide is 1:2.4:0.1. 5. The preparation method according to claim 2, characterized in that, the N,N-dimethylformamide in the step 1) is replaced with a mixed solvent of ethanol and N,N-dimethylformamide. 6. The preparation method according to claim 2, characterized in that, the microwave power in the step 1) is 30W, and the reaction time is 20min. 7. preparation method as claimed in claim 2 is characterized in that, described diaryl iodide trifluoromethanesulfonate is diphenyl iodide trifluoromethanesulfonate or two-(4-tolyl) iodine Triflate. 8. the application of a kind of triaryl sulfonium salt containing benzoxazole skeleton as photoinitiator as claimed in claim 1. 9. A UV-curable composition, characterized in that it contains the triarylsulfonium salt containing a benzoxazole skeleton according to claim 1.