WO2014033967A1

WO2014033967A1 - Photo acid generator and its synthetic method

Info

Publication number: WO2014033967A1
Application number: PCT/JP2012/073003
Authority: WO
Inventors: Yoshihiko Ikeda; Hiroyuki Kitayama
Original assignee: Rhodia Operations
Priority date: 2012-09-03
Filing date: 2012-09-03
Publication date: 2014-03-06

Abstract

A photo acid generator and/or a photo initiator consisting of sulfonium cation shown an formula (I) below and a tetra(fluorinated-aryl) borate anion; (In the formula (I), Ar¹ is an hydrocarbon group comprising at least an aromatic group, which can eventually be substituted with a halogen, nitro, hydroxyl, alkyl, alkoxy, phenoxy, ester, ether, aryl, thioester, thiocarbonyl, amino, amide, imide, nitrile, methacryloyl, epoxylated alkyl, thiophenyl, or phenylthiophenyl group, and Ar² is an aryl group substituted by at least a fluorine atom and/or a fluorinated alkyl group.)

Description

DESCRIPTION

Title of Invention

Photo Acid Generator and its synthetic method

Technical Field

The present invention relates to a Photo Acid Generator and its synthetic method. A photo acid generator and/or a photo initiator consisting of sulfonium cation shown an formula (I) below and a tetra(fluorinated-aryl) borate anion;

Θ

(Ar²)₄B

(In the formula (I), Ar¹ is an hydrocarbon group comprising at least an aromatic group, which can eventually be substituted with a halogen, nitro, hydroxyl, alkyl, alkoxy, phenoxy, ester, ether, aryl, thioester, thiocarbonyl, amino, amide, imide, nitrile, methacryloyl, epoxylated alkyl, thiophenyl, or phenylthiophenyl group, and Ar² is an aryl group substituted by at least a fluorine atom and/or a fluorinated alkyl group.)

Background Art

A photo initiator has been widely studied and industrially utilized for printing ink, paint, coating, resist applications, and many of them relate to polymerization of a vinyl group with radical initiation. However, these initiators are impossible to polymerize the cationic polymerization-group such as epoxy, oxetane and/or vinyl ether groups, and an effective initiator is desired to polymerize a material containing these functional groups. In order to polymerize epoxy and the like by light, a method was proposed to use a Lewis acid generated from a photosensitive aromatic diazonium compound as an initiator by photo-decomposition and then generate ring-opening polymerization of epoxy, however, there was a quality problem that the quality of a cured material was made worsening by nitrogen gas at the decomposition.

In order to solve this problem of a diazonium photo initiator, a triaryl sulfonium salt photo initiator was proposed to provide a good quality.

However, a triphenylsulfonium salt is not favorable for an industrial use due to the release of highy toxic benzene during its reaction. Thus a derivative replacing a phenyl group in triphenylsulfonium with phenylthiophenyl group was proposed as a triarylsulfonium moiety that would not release benzene with keeping the photosensitibity.

The derivative is favorable and advantageous to use because benzene is not released at the reaction that makes the C-S bond cleavage between the sulfur atom as the cation center and the carbon of phenythiophenyl group.

However, a diphenyphenylthiophenylsulfonium salt is poorly soluble in an organic media thus it is disadvantageous to use for pre-polymer and/or coating preparation.

In order to improve solubility, it is proposed to introduce tert-butyl, tert-octyl and 2-ethylhexyl groups into diphenylphenylthiophenylsulfonium moiety. However, the introduction of these groups is easy to undergo elimination of the above groups for solubilization at synthesis and causes the products to reduce the melting point of the sulfonium and/or to make waxy. Therefore, its production process and purification process become complicated.

An acid generated by photo decomposition of sulfonium salt usually has SbF6(-), PF6(-), AsF6(-), BF4(-), etc. as an inorganic conjugated base or a variety of sulfonates as an organic conjugate base in order to get high acidity.

Summary of Invention

Technical Problem

However, the sulfonium salts having an anion moiety listed above have a poor solubility in organic materials, and this poor solubility of the sulfonium salts often undergo insufficient curing of curable compositions.

In addition with it, a released acid is so strong that it damages a metal material contacted with the cured resin.

It was proposed to use a Bronsted acid having tetrakis(pentafluorophenyl)borate as a conjugated base as a countermeasure of the above problems to afford the significant improvement of solubility in organic materials and corrosiveness, however, it is still desired to improve the solubility of the sulfonium salts an acid precursor.

Solution to Problem

The inventors have eagerly made studies for keeping the reactivity and improving the solubility of triarylsulfonium borate derivatives. As a result of them, they have achieved to find that 2 aryl groups of a sulfonium cation to replace with p-xylyl group made a dramatic improvement of the solubility without any negative impact to the reactivity.

In addition with it, they also found to obtain a photo acid generator having high reactivity and solublity with the borate as a counter anion instead of tetrakis(pentafluorophenyl)borate generally known and used, such as 3,5-difluorophenyl, 3,4,5-trifluorophenyl, 3,5-bis(trifluorophenyl), 4-trifluoromethoxyphenyl, etc.

Advantageous Effects of Invention

This present invention provides a novel non-corrosive photo acid generator having high compatibility and solubility with organic materials, high stability that could provide a highly transparent photo-cured product with excellent physic-chemical properties.

Description of Embodiments

A photo acid generator and/or a photo initiator of the present invention consists of sulfonium cation shown an formula (I) below and a tetra(fluorinated-aryl) borate anion; such as tetrakis(pentafluorophenyl)borate anion.

Θ

(Ar²)₄B

In the formula (I), Ar¹ is an hydrocarbon group comprising at least an aromatic group, which can eventually be substituted with a halogen, nitro, hydroxyl, alkyl, alkoxy, phenoxy, ester, ether, aryl, thioester, thiocarbonyl, amino, amide, imide, nitrile, methacryloyl, epoxylated alkyl, thiophenyl, or phenylthiophenyl group.

In the formula (I), Ar² is an aryl group substituted by at least a fluorine atom and/or a fluorinated alkyl group.

The above group may have from 1 to 4 carbon atoms, wherein the moieties can be saturated or unsaturated hydrocarbon, aliphatic, cyclic or aromatic.

Ar¹ is preferably a 4-phenylthiophenyl group, eventually substituted with a halogen, nitro, hydroxy, alkyl, alkoxy, ester, ether, thioester, thiocarbonyl, amino, amide, imide, or nitrile.

Examples of the aromatic group may include phenyl, naphthyl, anthranyl, azulenyl, phenanthryl, anthryl, anthraquinonyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, indolizinyl, isoindolyl, indolyl, indazolyl, purinyl, quinolizinyl, isoquinolinyl, quinolinyl, naphthyridinyl, phthalazinyl, quinazolinyl, cinnolinyl, pteridinyl, phenanthridinyl, acridinyl, perimidinyl, phenanthrolinyl, thienyl, phenoxathiinyl, furyl, isobenzofuranyl, benzofuranyl, or isochromenyl group.

Examples of the alkyl group may include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, or sec-butyl group. Examples of the alkoxy group may include methoxy, ethoxy, propoxy, and butoxy group, and the alkoxy group is preferably methoxy or ethoxy group.

Compound of formula (I) may be preferably compound of formula (II).

In the formula (II), R1 , R2 and R3 is hydrogen, alkyl, nitro, alkoxy, phenyl, phenoxy, or thiophenyl group.

Ar² may be fluoromethyl, difluoromethyl, trifluoromethyl, difluoroethyl or perfluoroethyl group.

Ar² may be any one of substituted groups shown in the formula (III).

The tetra(fluorinated-aryl) borate anions may be any of the anions shown formula (IV).

In the present invention, Di-2,5-xylylsulfoxide is easily synthesized with Fridel-Craft reaction of p-xylene with thionyl chloride or sulfur dioxide.

The key difference from the prior arts is that the present invention focuses on a sulfonium salt having two 2,5-xylyl group attached to sulfur atom of a sulfonium cation. The effect of two 2,5-xylyl group can give higher solubility than phenyl group to a sulfonium cation without a significant loss of crystallizability of it due to its symmetry. A product synthesized with the prior arts is given a higher solubility, however, it loses crystallizability and faces to a difficulty for purification with crystallization and/or solidification.

Examples

Hereinafter, embodiments of the present invention will be discussed, however, the present invention is not limited to these embodiments.

(Synthesis of dixylylsulfoxide 1)

212.34 g (2 mol) of p-xylene, 266.68 g (2 mol) of anhydrous aluminum chloride and 1 L of chloroform were placed in a 2 L 4-necked flask with a thermometer, a mechanical stirrer, a condenser and a dropping funnel, and then the mixture was cooled below 10 degree C in an ice bath.

118.97 g (1 mol) of thionyl chloride was added dropwise to the mixture as early as with keeping the reaction mixture below 30 degree C, and then it was poured into 2 kg of a mixture of ice and water after being stirred for 15 minutes below 30 degree C.

1 L of chloroform was further added to the above mixture. The organic layer was washed with 1 L each of 10% aqueous sodium hydroxide, water and brine after phase separation, and it was dried over with a drying agent.

The drying agent was filtered off, and the filtrate was heated to remove chloroform and the unreacted xylene. 2 L of cyclohexane was added to the residue and the solution was heated and the insoluble material was removed by filtration.

The filtrate was cooled to crystallize a product to afford 165.97 g (0.6433 mol) of di-2,5-xylylsulfoxide.

(Synthesis of dixylylsulfoxide 2)

212.34 g (2 mol) of p-xylene, 10 g of zeolite powder (abt 5 %), and 1 g of trifluoromethanesulfonic acid and 1 L of chloroform were placed in a 2 L 4-necked flask with a thermometer, a mechanical stirrer, a condenser and a gas introducer, a dropping funnel and a gas absorber, and then the mixture was cooled below 30 degree C in a water bath.

64.07 g (1 mol) of sulfur dioxide gas was introduced to the mixture with keeping the temperature below 30 degree C, and with keeping the out gas volume minimized.

After the addition of sulfur dioxide, the reaction mixture was stirred below 30 degree C. for 1 hour, then zeolite used for the reaction as a catalyst was filtered off.

The filtrate was washed with 1 L each of water, 5% aqueous sodium hydroxide, water, and brine then dried over with a drying agent.

After filtering the drying agent, chloroform and unreacted p-xylene were evaporated and 2 L of cyclohexane was added to the residue. The solution was heated and the insoluble material was filtered off.

The filtrate was cooled to crystallize a product to afford 130.09 g (0.5042 mol) of di-2,5-xylylsulfoxide.

(Synthesis of sulfonium borate A)

10.1 g (0.05 mol) of diphenylsulfoxide, 9.31 g (0.05 mol) of diphenylsulfide were placed into a 4-necked 500 mL flask with a condenser, a thermometer, a dropping funnel and a mechanical stirrer, in an ice-water bath, and then 42.93 g (0.45 mol) of methanesulfonic acid was dropwise added to the above mixture with keeping the temperature below 20 degree C.

After the addition of methanesulfonic acid, 9.29 g (0.10 mol) acetic anhydride was dropwise added to the mixture with keeping the reaction mixture below 40 degree C.

The resulting mixture was stirred at 35 to 40 degree C. for 1 hour after acetic anhydride was added completely.

The reaction was quenched with an addition of 170 mL of water with keeping the temperature below 20 degree C, and the mixture was stirred for 1 hour. After the hydrolysis of the excess acetic anhydride, the reaction mixture was washed 3 times with 100 mL of ethyl acetate to remove unreacted di-2,5-xylylsulfoxide and diphenyl sulfide. The product was extracted 3 times with 100 mL of chloroform. The combined chloroform layer was washed with 100 mL of water and dried over magnesium sulfate.

The solution was passed through a short pass column of 100 g of silica gel to remove highly polar and colored components, then evaporated and dried up to afford diphenylphenylthiophenylsulfonium mesylate.

Thus obtained crude product of the sulfonium mesylate was dissolved into 100 mL of chloroform and the mixture was placed into a 500 mL of 4-neck flask a reflux condenser, a thermometer, a dropping funnel and a stirrer.

368.6 g (0.0525 mol) of 10% aqueous solution of sodium tetrakis(pentafluorophenyl)borate was added to the solution with keeping the temperature 25 degree C. that was stirred for 1 hour.

After the reaction was quenched, the product was extracted 3 times with 200 mL of chloroform. The combined chloroform layer was dried and then passed through a short pass column of silica gel to remove highly polar and colored components.

The chloroform solution was evaporated and the residue wad dissolved in 1 L of isopropanol. The isopropanol solution was slowly added into 3 L of deionized water to reprecipitate the product.

The obtained solid material was dried over to afford 47.44 g (0.0452 mol) of diphenyl-4-phenylthiophenylsulfonium tetrakis(pentafluorophenyl)borate in 90.31% yield.

(Synthesis of sulfonium borate B)

12.9 g (0.05 mol) of di-2,5-xylylsulfoxide, 9.31 g (0.05 mol) of diphenylsulfide were placed into a 4-necked 500 mL flask with a condenser, a thermometer, a dropping funnel and a mechanical stirrer, in an ice-water bath, and then 42.93 g (0.45 mol) of methanesulfonic acid was dropwise added to the above mixture with keeping the temperature below 20 degree C.

After the addition of methanesulfonic acid, 9.29 g (0.10 mol) acetic anhydride was dropwise added to the mixture with keeping the reaction mixture below 40 degree C. The resulting mixture was stirred at 35 ~ 40 degree C. for 1 hour after acetic anhydride was added completely.

The reaction was quenched with an addition of 170 ml. of water with keeping the temperature below 20 degree C, and the mixture was stirred for 1 hour. After the hydrolysis of the excess acetic anhydride, the reaction mixture was washed 3 times with 100 ml_ of ethyl acetate to remove unreacted di-2,5-xylylsulfoxide and diphenyl sulfide.

The product was extracted 3 times with 100 mL of chloroform. The combined chloroform layer was washed with 100 mL of water and dried over magnesium sulfate. The solution was passed through a short pass column of 100 g of silica gel to remove highly polar and colored components, then evaporated and dried up to afford di-2,5-xylylphenylthiophenylsulfonium mesylate.

368.6 g (0.0525 mol) of 10% aqueous solution of sodium tetrakis(pentafluorophenyl)-borate was added to the solution with keeping the temperature 25 degree C. that was stirred for 1 hour.

The chloroform solution was evaporated and the residue wad dissolved in 350 mL of isopropanol. The isopropanol solution was slowly added into 2 L of deionized water to reprecipitate the product.

The obtained solid material was dried over to afford 50.64 g (0.046 mol) of di-2,5-xylyl-4-phenylthiophenylsulfonium tetrakis(pentafluorophenyl)borate in 91.5% yield.

(Synthesis of sulfonium borate C)

After the addition of methanesulfonic acid, 9.29 g (0.10 mol) acetic anhydride was dropwise added to the mixture with keeping the reaction mixture below 40 degree C. The resulting mixture was stirred at 35 to 40 degree C. for 1 hour after acetic anhydride was added completely.

The reaction was quenched with an addition of 170 mL of water with keeping the temperature below 20 degree C, and the mixture was stirred for 1 hour. The hydrolysis of the excess acetic anhydride, the reaction mixture was washed 3 times with 100 mL of ethyl acetate to remove unreacted di-2,5-xylylsulfoxide and diphenyl sulfide.

The product was extracted 3 times with 100 mL of chloroform. The combined chloroform layer was washed with 100 mL of water and dried over magnesium sulfate.

The solution was passed through a short pass column of 100 g of silica gel to remove highly polar and colored components, then evaporated and dried up to afford di-2,5-xylylphenylthiophenylsulfonium mesylate.

Thus obtained crude product of the sulfonium mesylate was dissolved into 100 mL of chloroform and the mixture was placed into a 500 mL of 4-neck flask a reflux condenser, a thermometer, a powder funnel and a stirrer.

46.53 g (0.0525 mol) of sodium tetrakis{bis-(3,5-trifluoromethyl)phenyl}borate (powder) was added to the solution at room temperature with keeping the vigorous stirring for 1 hour to dissolve the powder completely.

After the reaction was quenched, the product was extracted 3 times with 200 mL of chloroform. The combined chloroform layer was dried and then passed through a short pass column of 200 g of silica gel to remove highly polar and colored components.

The chloroform solution was evaporated and the residue wad dissolved in 200 mL of isopropanol. The isopropanol solution was slowly added into 2 L of deionized water to reprecipitate the product.

The obtained solid material was filtered and dried over to afford 60.56 g (0.047 mol) of di-2,5-xylyl-4-phenylthiophenylsulfonium tetrakis{bis(3,5-trifluoromethyl)phenyl}borate in 93.83% yield.

(Synthesis of sulfonium borate D)

35.6 g (0.0525 mol) of sodium tetrakis(4-trifluoromethoxyphenyl)borate as sodium borate was used with the same procedure as Synthesis of sulfonium borate 3, except the volume of isopropanol for the dissolution of the crude product for reprecipitation, to afford 44.91 g (0.041 mol) of di-2,5-xylyl-4-phenylthiophenylsulfonium tetrakis(4-trifluoromethoxyphenyl)borate in 81.22% yield.

(Synthesis of sulfonium borate E)

29.30 g (0.0525 mol) of sodium tetrakis(3,4,5-trifluorophenyl)borate as sodium borate was used with the same procedure as Synthesis of sulfonium borate 4 to afford 45.7 g (0.048 mol) of di-2,5-xylyl-4-phenylthiophenylsulfonium tetrakis(3,4,5-trifluorophenyl)borate in 95.01% yield.

(Synthesis of sulfonium borate F)

25.52 g (0.0525 mol) of sodium tetrakis(3,4-difluorophenyl)borate as sodium borate was used with the same procedure as Synthesis of sulfonium borate 4 to afford 39.9 g (0.045 mol) of di-2,5-xylyl-4-phenylthiophenyl-sulfonium tetrakis(3,4-difluorophenyl)borate in 89.60% yield.

(Evaluation of UV curing)

The evaluation was conducted by measuring pencil hardness of the film of a mixture of 3 wt% of the sulfonium borate produced above, dissolved in the aliphatic cyclic epoxide shown in the formula (V) below after coated by a wire bar with 10 micrometer on a PET film cured by a high pressure mercury lump. Then curing situation was evaluated by pencil hardness test (HB). The evaluation results are shown in Table 1.

(Table 1)

Time to make a 10 micro meter film of the epoxide HB as pencil hardness.

(Evaluation of solubility)

The evaluation of solubility (g/100ml) was conducted for the sulfonium borate produced above. The evaluation results are shown in Table 2.

(Table 2)

(Evaluation of corrosiveness)

A 3 cm square metal plate was soaked in IPA solution of 0.5% of the sulfonium borate produced above in a tightly closed bottle at a cool and dark place during a week. Then the surface of each plate was observed and evaluated by the standards below. The evaluation results are shown in Table 3.

Observed no change on the surface: 1

Observed the solution color change and/or the tarnished surface of a test plate: 2 Observed the surface rusted of a test plate: 3

(Table 3)

(corrosiveness) A B c D E F

Iron 1 1 1 1 1 1

Copper 1 1 1 1 1 1

Aluminum 1 1 1 1 1 1

Claims

[Claim 1]

A photo acid generator and/or a photo initiator consisting of sulfonium cation shown an formula (I) below and a tetra(fluorinated-aryl) borate anion;

Θ

(Ar²)₄B

(In the formula (I), Ar¹ is an hydrocarbon group comprising at least an aromatic group, which can eventually be substituted with a halogen, nitro, hydroxyl, alkyl, alkoxy, phenoxy, ester, ether, aryl, thioester, thiocarbonyl, amino, amide, imide, nitrile, methacryloyi, epoxylated alkyl, thiophenyl, or phenylthiophenyl group, and Ar² is an aryl group substituted by at least a fluorine atom and/or a fluorinated alkyl group.)

[Claim 2]

The photo acid generator and/or a photo initiator of claim 1 , wherein the aromatic group is phenyl, naphthyl, anthranyl, azulenyl, phenanthryl, anthryl, anthraquinonyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, indolizinyl, isoindolyl, indolyl, indazolyl, purinyl, quinolizinyl, isoquinolinyl, quinolinyl, naphthyridinyl, phthalazinyl, quinazolinyl, cinnolinyl, pteridinyl, phenanthridinyl, acridinyl, perimidinyl, phenanthrolinyl, thienyl, phenoxathiinyl, furyl, isobenzofuranyl, benzofuranyl, or isochromenyl group.

[Claim 3]

The photo acid generator and/or a photo initiator of claim 1 or 2, wherein the alkyl group is methyl, ethyl, propyl, isopropyl, butyl, isobutyl, or sec-butyl group.

[Claim 4]

The photo acid generator and/or a photo initiator of any one of claims 1 to 3, wherein the alkoxy group is methoxy, ethoxy, propoxy, or butoxy group.

[Claim 5]

The photo acid generator and/or a photo initiator of any one of claims 1 to 4, wherein the compound of formula (I) is a compound of formula (II);

(In the formula (II), R1, R2 and R3 is hydrogen, alkyl, nitro, alkoxy, phenyl, phenoxy, or thiophenyl group.)

[Claim 6]

The photo acid generator and/or a photo initiator of any one of claims 1 to 5, wherein the Ar² is fluoromethyl, difluoromethyl, trifluoromethyl, difluoroethyl or perfluoroethyl group.

[Claim 7]

The photo acid generator and/or a photo initiator of any one of claims 1 to 6, wherein the Ar² is any one of substituted groups shown in the formula (III);

[Claim 8]

The photo acid generator and/or a photo initiator of any one of claims 1 to 7, wherein the tetra(fluorinated-aryl) borate anion is any of the anions shown in the formula (IV);

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