Cationic photoinitiator and preparation method and use thereof

Abstract

This invention discloses a novel cationic photoinitiator and a preparation method and use thereof. The cationic photoinitiator has a structure as represented by general formula (I) below. It can match a longer absorption wavelength in the process of application and has an outstanding photosensitive property, and has characteristics of no proneness to migration and good yellowing resistance. ##STR00001##

Claims

1. A cationic photoinitiator, wherein the cationic photoinitiator has a structure as represented by general formula (I): ##STR00033## wherein, R.sub.1 and R.sub.2 each independently represent a halogen, OH, CN, NO.sub.2, a C.sub.1-C.sub.20 linear or branched alkyl group, a C.sub.3-C.sub.20 cycloalkyl group, a C.sub.4-C.sub.20 cycloalkylalkyl group, a C.sub.4-C.sub.20 alkylcycloalkyl group, or a C.sub.6-C.sub.40 aryl or heteroaryl group, wherein —CH.sub.2— may be optionally substituted with —O—, —S—, —NH—, —CO—, —COO—, or —OCO—; m.sup.1 and m.sup.2 represent numbers of R.sub.1 and R.sub.2 respectively, and m.sup.1 and m.sup.2 are each independently an integer of 0, 1, 2 or 3; R.sub.4 and R.sub.5 each independently hydrogen, a C.sub.1-C.sub.8 linear or branched alkyl group, a C.sub.3-C.sub.6 cycloalkyl group, or a C.sub.4-C.sub.10 cycloalkylalkyl group, wherein acyclic —CH.sub.2— may be optionally substituted with —O—, —S—, —CO—, —COO—, or —OCO—; or optionally, R.sub.4 and R.sub.5 may be linked to each other, along with the carbon to which they are attached, to form a cycloalkyl group; R.sub.6 and R.sub.7 may be the same or may be different, and each independently represent a phenyl group, a diphenyl sulfide group, a benzophenone group, a fluorenyl group, a diphenyl ether group, or a carbazolyl group, each of which may be optionally substituted with a halogen, CN, NO.sub.2, or a C.sub.1-C.sub.8 alkyl group, and —CH.sub.2— in the C.sub.1-C.sub.8 alkyl group may be optionally substituted with —O—, —S—, —CO—, —COO—, or —OCO—; R.sub.3 represents hydrogen, a halogen, CN, NO.sub.2, R.sub.8, —CO—R.sub.8, or a S.sup.+(R.sub.6)(R.sub.7) group; R.sub.8 represents a C.sub.1-C.sub.10 linear or branched alkyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.4-C.sub.15 cycloalkylalkyl group, a C.sub.6-C.sub.20 aryl group, or a C.sub.7-C.sub.20 arylalkyl group, wherein the cycloalkyl structure and the aryl structure, may be optionally substituted with a C.sub.1-C.sub.6 alkyl group, and —CH.sub.2— may be optionally substituted with —O—, —S—, —NH—, —CO—, —COO—, or —OCO—; X.sup.− represents a non-nucleophilic anion; and n is 1 or 2.

2. The cationic photoinitiator according to claim 1, wherein R.sub.1 and R.sub.2 each independently represent a halogen, OH, CN, NO.sub.2, a C.sub.1-C.sub.10 linear or branched alkyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.4-C.sub.12 cycloalkylalkyl group, a C.sub.4-C.sub.12 alkylcycloalkyl group, or a C.sub.6-C.sub.20 aryl or heteroaryl group, wherein —CH.sub.2— may be optionally substituted with —O—, —S—, —NH—, —CO—, —COO—, or —OCO—.

3. The cationic photoinitiator according to claim 1, wherein m.sup.1 and m.sup.2 are each independently an integer of 0, 1, or 2.

4. The cationic photoinitiator according to claim 1, wherein R.sub.6 and R.sub.7 each independently represent a phenyl group, a diphenyl sulfide group, a benzophenone group, a fluorenyl group, a diphenyl ether group, or a carbazolyl group, each of which may be optionally substituted with CN, NO.sub.2, or a C.sub.1-C.sub.4 alkyl group, and —CH.sub.2— in the C.sub.1-C.sub.4 alkyl group may be optionally substituted with —O—, —S—, —CO—, —COO—, or —OCO—.

5. The cationic photoinitiator according to claim 1, wherein R.sub.3 represents hydrogen, a halogen, CN, NO.sub.2, R.sub.8, —CO—R.sub.8, or a S.sup.+(R.sub.6)(R.sub.7) group; R.sub.8 represents a C.sub.1-C.sub.6 linear or branched alkyl group, a C.sub.3-C.sub.8 cycloalkyl group, a C.sub.4-C.sub.10 cycloalkylalkyl group, a C.sub.6-C.sub.10 aryl group, or a C.sub.7-C.sub.12arylalkyl group, wherein the cycloalkyl structure and the aryl structure may be optionally substituted with a C.sub.1-C.sub.4 alkyl group, and acyclic —CH.sub.2— may be optionally substituted with —O—, —S—, —NH—, —CO—, —COO—, or —OCO—.

6. The cationic photoinitiator according to claim 1, wherein when R.sub.3 represents a S.sup.+(R.sub.6)(R.sub.7) group, R.sub.3 is bilaterally symmetrical with a S.sup.+(R.sub.6)(R.sub.7) group on the other side.

7. The cationic photoinitiator according to claim 1, wherein X.sup.− is C.sub.mF.sub.2m+1SO.sub.3.sup.−, BF.sub.4.sup.−, SbF.sub.6.sup.−, AsF.sub.6.sup.−, PF.sub.6.sup.−, or B(C.sub.6Q.sub.5).sub.4.sup.−, wherein Q represents hydrogen or a halogen, and m is an integer of 1-8.

8. The cationic photoinitiator according to claim 1, wherein a value of n is the same as a number of S.sup.+(R.sub.6)(R.sub.7) groups in the general formula (I).

9. A preparation method of the cationic photoinitiator of claim 1, wherein a reaction process flow used is as shown below: ##STR00034## wherein R.sub.3′ represents hydrogen when R.sub.3 represents a S.sup.+(R.sub.6)(R.sub.7) group, and R.sub.3′ represents R.sub.3 in other occurrences; the preparation method comprises: (1) synthesis of the intermediate, wherein the raw material a and the raw material b are subjected to Friedel-Crafts reaction in an organic solvent under the action of aluminum trichloride or zinc chloride to synthesize the intermediate; (2) synthesis of the product, wherein the intermediate is added to an organic solvent in which NaX or KX is dissolved and dissolved with stirring, deionized water is subsequently added with stirring to precipitate a solid, and suction filtration and recrystallization are performed to obtain the product; and X in the NaX and the KX represents a non-nucleophilic anion.

10. The cationic photoinitiator according to claim 1, wherein both m.sup.1 and m.sup.2 are 0.

11. The cationic photoinitiator according to claim 2, wherein both m.sup.1 and m.sup.2 are each independently an integer of 0, 1, or 2.

12. The cationic photoinitiator according to claim 2, wherein both m.sup.1 and m.sup.2 are 0.

13. The cationic photoinitiator according to claim 5, wherein when R.sub.3 represents a S.sup.+(R.sub.6)(R.sub.7) group, R.sub.3 is bilaterally symmetrical with a S.sup.+(R.sub.6)(R.sub.7) group on the other side.

Description

DESCRIPTION OF EMBODIMENTS

(1) Hereafter, this invention will be further illustrated in conjunction with specific Examples, but it is not to be understood that the scope of this invention is limited thereto.

PREPARATION EXAMPLE

Example 1

(2) ##STR00014##

(3) (1) Preparation of intermediate 1a

(4) 83 g of a raw material 1a, 67 g of aluminum trichloride, and 200 mL of dichloromethane were added to a 1000 mL four-neck flask, and the temperature was reduced to 0° C. by an ice water bath. 101 g of a raw material 1b was dissolved in 200 mL of dichloromethane to form a mixed solution. The mixed solution was subsequently charged into a dropping funnel, and the temperature was controlled at 10° C. or less. This mixed solution was dropped into the four-neck flask within about 2 h. Stirring was continued for 24 h after completion of dropping, and liquid phase tracking was performed until the concentration of the raw materials did not change any longer. The materials were then slowly poured into 800 g of deionized water with stirring to precipitate a solid, and suction filtration was performed to obtain a light yellow solid. This light yellow solid was dried in an oven at 80° C. for 2 h to obtain 152 g of the intermediate 1a with a yield of 79% and a purity of 98%.

(5) (2) Preparation of compound 1

(6) 152 g of potassium hexafluorophosphate was dissolved in 150 mL of acetone, and 115 g of the intermediate 1a prepared in step (1) was then added. Stirring was performed at normal temperature until the intermediate 1a was dissolved. 300 mL of deionized water was then added to precipitate a white solid, suction filtration and recrystallization with methanol were performed to obtain 196 g of a solid. The solid was dried at 70° C. for 5 h to obtain the compound 1 with a yield of 92% and a purity of 98%.

(7) The structure of the product was confirmed by MS and .sup.1H-NMR.

(8) MS(m/z): 352 (M+1).sup.+;

(9) .sup.1H-NMR (CDCl.sub.3, 500 MHz): 3.9013 (2H, s), 7.3611-7.7658 (18H, m).

Example 2

(10) ##STR00015##

(11) (1) Preparation of Intermediate 2a

(12) 40 g of a raw material 2a, 14 g of aluminum trichloride, and 50 mL of dichloromethane were added to a 500 mL four-neck flask, and the temperature was reduced to 0° C. by an ice water bath. 31 g of a raw material 2b was dissolved in 50 mL of dichloromethane to form a mixed solution. The mixed solution was subsequently charged into a dropping funnel, and the temperature was controlled at 10° C. or less. This mixed solution was dropped into the four-neck flask within about 2 h. Stirring was continued for 24 h after completion of dropping, and liquid phase tracking was performed until the concentration of the raw materials did not change any longer. The materials were then slowly poured into 200 g of deionized water with stirring to precipitate a solid, and suction filtration was performed to obtain a light yellow solid. This light yellow solid was dried in an oven at 80° C. for 2 h to obtain 46 g of the intermediate 2a with a yield of 64% and a purity of 98%.

(13) (2) Preparation of Compound 2

(14) 45 g of sodium tetrakis(pentafluorophenyl) borate was dissolved in 100 mL of acetone, and 43 g of the intermediate 2a prepared in step (1) was then added. Stirring was performed at normal temperature until the intermediate 2a was dissolved. 200 mL of deionized water was then added to precipitate a white solid, suction filtration and recrystallization with methanol were performed to obtain 76 g of a solid. The solid was dried at 70° C. for 5 h to obtain the compound 2 with a yield of 90% and a purity of 98%.

(15) MS(m/z): 687 (M+1).sup.+;

(16) .sup.1H-NMR (CDCl.sub.3, 500 MHz): 0.9642 (6H, t), 1.1332-1.1932 (4H, m), 1.2911-1.3027 (4H, m), 1.8694-1.8663 (4H, m), 2.3433 (3H, s), 7.3281-8.1477 (24H, m).

Example 3

(17) ##STR00016##

(18) (1) Preparation of Intermediate 3a

(19) 22 g of a raw material 3a, 28 g of aluminum trichloride, and 50 mL of dichloromethane were added to a 500 mL four-neck flask, and the temperature was reduced to 0° C. by an ice water bath. 46 g of a raw material 3b was dissolved in 100 mL of dichloromethane to form a mixed solution. The mixed solution was subsequently charged into a dropping funnel, and the temperature was controlled at 10° C. or less. This mixed solution was dropped in the four-neck flask within about 2 h. Stirring was continued for 24 h after completion of dropping, and liquid phase tracking was performed until the raw materials did not change any longer. The materials were then slowly poured into 200 g of deionized water with stirring to precipitate a solid, and suction filtration was performed to obtain a light yellow solid. This light yellow solid was dried in an oven at 80° C. for 2 h to obtain 56 g of the intermediate 3a with a yield of 65% and a purity of 98%.

(20) (2) Preparation of Compound 3

(21) 60 g of Sodium Perfluorobutylsulfonate was Dissolved in 100 mL of Acetone, and 55 g of the intermediate 3a prepared in step (1) was then added. Stirring was performed at normal temperature until the intermediate 3a was dissolved. 200 mL of deionized water was then added to precipitate a white solid, suction filtration and recrystallization with methanol were performed to obtain 88 g of a solid. The solid was dried at 70° C. for 5 h to obtain the compound 3 with a yield of 90% and a purity of 98%.

(22) MS(m/z): 650 (M+1).sup.+;

(23) .sup.1H-NMR (CDCl.sub.3, 500 MHz): 0.9444-0.9601 (6H t), 1.9086-1.9146 (4H, m), 2.3607 (12H, s), 7.1061-7.7677 (22H, m).

Examples 4-18

(24) Compounds 4-18 as shown in Table 1 below were synthesized by using corresponding raw materials with reference to the methods of Examples 1-3. The structures of compounds of interest and mass spectrometry data thereof were listed in Table 1.

(25) TABLE-US-00001 TABLE 1 MS Example Compound (m/z) Example 4    Compound 4 408 Example 5    Compound 5 492 Example 6    Compound 6 481 Example 7  0   Compound 7 574 Example 8    Compound 8 711 Example 9    Compound 9 394 Example 10   Compound 10 514 Example 11   Compound 11 616 Example 12   Compound 12 572 Example 13   Compound 13 572 Example 14   Compound 14 586 Example 15   Compound 15 588 Example 16   Compound 16 650 Example 17 0   Compound 17 496 Example 18   Compound 18 807

(26) Evaluation of Properties

(27) By formulating exemplary photocurable compositions, various application properties of the photoinitiator represented by formula (I) of this invention were evaluated, including aspects of photosensitive property, storage stability, mobility, yellowing resistance, and the like.

(28) 1. Formulation of Photocurable Compositions

(29) Photocurable compositions were formulated according to the formulations as shown in Table 2. A cationic photoinitiator was first dissolved in a solvent, which was propylene carbonate, and then evenly mixed with a cation polymerizable monomer to obtain a photocurable composition by formulation.

(30) Here, the cation polymerizable monomer was one or a combination of two or more of A1, A2, and A3: A1: 3′,4′-epoxycyclohexylmethyl 3,4-epoxycyclohexyl carboxylate (CAS: 2386-87-0); A2: bis(3,4-epoxycyclohexylmethyl) adipate (CAS: 3130-19-6); A3: 1,4-cyclohexanedimethanol divinyl ether (CAS: 17351-75-6).

(31) The cationic photoinitiator was the cationic photoinitiator of this invention or a compound A and/or B as comparison.

(32) ##STR00032##

(33) The usage amounts of the components in Table 2 were all parts by mass.

(34) TABLE-US-00002 TABLE 2 Example/Comparative Type, usage amount Example of photoinitiator Solvent A1 A2 A3 Example 19 Compound 1, 1 1 98 Example 20 Compound 1, 1 1 98 Example 21 Compound 2, 1 1 98 Example 22 Compound 2, 1 1 98 Example 23 Compound 3, 1 1 98 Example 24 Compound 3, 1 1 50 48 Example 25 Compound 10, 1 1 98 Example 26 Compound 15, 1 1 98 Example 27 Compound 16, 1 1 98 Example 28 Compound 17, 1 1 50 48 Example 29 Compound 18, 1 1 50 48 Comparative Example 1 Compound A, 1 1 98 Comparative Example 2 Compound A, 1 1 98 Comparative Example 3 Compound B, 1 1 98 Comparative Example 4 Compound B, 1 1 98 Comparative Example 5 Compound B, 1 1 50 48

(35) 2. Test of Photosensitive Property

(36) The composition described above was stirred under a yellow light lamp. Materials were taken on a PET template and roll coating was performed to form a film, and the solvent was removed by drying at 90° C. for 5 min, to form a coating film with a film thickness of about 2 μm. A substrate formed with the coating film was cooled to room temperature, and the coating film was exposed with an exposure time of 2 s by irradiating with a high-pressure mercury lamp (exposure machine model: RW-UV70201, wavelength: 200-500 nm, light intensity: 100 mW/cm.sup.2) and placed at room temperature for 2 min to observe the pencil hardness of a cured film thereof (the test method was referred to GB/T 6739-1986). A higher pencil hardness indicated a better photocurability of a composition, that is, the sensitivity of the initiator was more excellent.

(37) The evaluation was performed according to the criteria described below.

(38) ⊚: The pencil hardness was 2H or more.

(39) ∘: The pencil hardness was H-2B.

(40) .circle-solid.: The pencil hardness was 2B or less or its pencil hardness could not be measured.

(41) 3. Evaluation of Mobility

(42) The composition described above was stirred under a yellow light lamp. Materials were taken on a PET template and roll coating was performed to form a film, the solvent was removed by drying at 90° C. for 5 min, to form a coating film with a film thickness of about 2 μm. A substrate formed with the coating film was cooled to room temperature, and the coating film was exposed with an exposure time of 4 s by irradiating with a high-pressure mercury lamp (exposure machine model: RW-UV70201, wavelength: 200-500 nm, light intensity: 100 mW/cm.sup.2) to obtain a desired cured film. Next, 10 mL of methanol was used as a simulation liquid, and the cured film was placed in the simulation liquid and placed at room temperature for 24 h. The amount of the precipitated photoinitiator was analyzed with HPLC (LC-MS2020, Shimadzu, mobile phase: methanol/water=55/45, 0.5% dihydrogen phosphate salt). Content percentages of peaks in the liquid phase were used for comparison. The lower the relative content of the initiator in the liquid phase was, the less possibly the migration would occur.

(43) The evaluation was performed according to the criteria described below.

(44) ⊚: The initiator was not detected.

(45) .circle-solid.: The initiator was detected.

(46) 4. Evaluation of Yellowing Resistance

(47) The composition described above was stirred under a yellow light lamp. Materials were taken on a PET template and roll coating was performed to form a film, the solvent was removed by drying at 90° C. for 5 min, to form a coating film with a film thickness of about 2 μm. A substrate formed with the coating film was cooled to room temperature, and the coating film was exposed with an exposure time of 4 s by irradiating with a high-pressure mercury lamp (exposure machine model: RW-UV70201, wavelength: 200-500 nm, light intensity: 100 mW/cm.sup.2) to obtain a desired cured film.

(48) Next, an RW-UV.2BP ultraviolet aging test tank was used for performing an aging test. The light source was a high-pressure mercury lamp (dominant wavelength: 365 nm, total power: about 2.2 KW). The cured film was continuously irradiated for 6 h, and the condition of yellowing of the cured film was observed:

(49) ⊚: It is colorless and transparent, and the surface was smooth.

(50) ∘: It is yellowish, or the surface was sticky.

(51) .circle-solid.: The surface yellowed and the viscosity increased.

(52) 5. Storage Stability

(53) The photocurable composition obtained above was heated under protection from light in an oven at 80° C. for 24 h, and preserved under protection from light at normal temperature for 1 month. The viscosities of the composition before heating and after placing for 1 month were measured. A less increased viscosity indicated a better storage stability.

(54) The evaluation was performed according to the criteria described below.

(55) ⊚: The change in the viscosity was less than 1.5 times.

(56) ∘: The change in the viscosity was 1.5 times or more.

(57) Evaluation results were seen in Table 3.

(58) TABLE-US-00003 TABLE 3 Examples/Comparative Photosensitive Yellowing Storage Examples property Mobility resistance stability Example 19 ⊚ ⊚ ⊚ ⊚ Example 20 ⊚ ⊚ ⊚ ⊚ Example 21 ⊚ ⊚ ⊚ ⊚ Example 22 ⊚ ⊚ ⊚ ⊚ Example 23 ⊚ ⊚ ⊚ ⊚ Example 24 ⊚ ⊚ ⊚ ⊚ Example 25 ⊚ ⊚ ⊚ ⊚ Example 26 ⊚ ⊚ ⊚ ⊚ Example 27 ⊚ ⊚ ⊚ ⊚ Example 28 ⊚ ⊚ ⊚ ⊚ Example 29 ⊚ ⊚ ⊚ ⊚ Comparative .circle-solid. ◯ .circle-solid. ◯ Example 1 Comparative .circle-solid. ◯ .circle-solid. ◯ Example 2 Comparative ◯ ◯ ◯ ◯ Example 3 Comparative ◯ ◯ ◯ ◯ Example 4 Comparative ◯ ◯ ◯ ◯ Example 5

(59) As could be seen from the results in Table 3, compared to a conventional sulfonium salt photoinitiator (compounds A and B), the photocurable composition using the cationic photoinitiator of this invention has an outstanding photosensitive property, pencil hardnesses of cured films exceeding 2H, and has characteristics of no proneness to migration, better yellowing resistance, and better storage stability.

(60) It is to be noted that with respect to each of the cationic photoinitiators used in Examples 19-29, the molecular weight is greater than that of the compound A or B, the molar amount is relatively small in the case of the same mass, and the pencil hardness is 2H or more. This further demonstrates the advantages of the photoinitiator of this invention in terms of the photosensitive property.