WO2016000477A1 - (4-phenyl benzoyl) benzoate and use thereof as photoinitiator - Google Patents

Abstract

Provided are a compound represented by formula (I), a method of synthesizing same and a use thereof as photoinitiator. In the formula, each A represents an oxygen atom or independently represents a group of formula (AA), (BB) or (CC); G represents a residue of a polyol compound comprising n hydroxyl groups and 2 ≤ n ≤ 6; x1 is a positive integer, 2 ≤ x1 ≤ n and x2 is n-x; and R represents a hydrogen atom, a C1-C12 alkyl acyl, an aryl acyl or a C2-C4 conjugated alkenoyl.

Description

(4-Phenylbenzoyl)benzoate and its use as a photoinitiator Technical field

The present invention relates to a macromolecularized (4-phenylbenzoyl) benzoate. The compound can be used as a photoinitiator alone or in combination with other photoinitiators for formulating photocurable compositions, particularly suitable for photocuring varnishes, printing inks and the like which require low odor, low migration. The present invention also provides a photopolymerizable composition comprising at least one compound of the present invention as a photoinitiator to formulate an unsaturated carbon-carbon double bond-containing compound.

Background technique

Photoinitiators for photocuring varnish formulations require good cure speeds, especially good surface cure activity, low odor, low yellowness, and good solubility. In addition, as consumers become more sensitive to the contamination of foreign compounds in foods, especially for food and drug packaging materials, which limits the amount of material migration, many small molecular weight substances are excluded from the permitted list, such as Compounds such as benzophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and methyl benzoylcarboxylate have small molecular weights, and they may be formed during the construction of the composition and after polymerization and film formation. Contamination caused by migration to its contact or volatilization into the air. Therefore, the tendency of the compound used for the photoinitiator to migrate out of the carrier to which it is attached or to be dissolved by the external medium should also be as small as possible.

Benzophenone is still the most widely used photoinitiator for ultraviolet (UV) cured overprint varnishes because of its good surface cure, high solubility, and low cost, but benzophenone has a strong odor and is extremely easy to print. Migrate and dissolve into packaged foods.

At present, some macromolecularized benzophenone derivatives and polyfunctional benzophenone derivatives have been disclosed on the market or in technical materials, such as those disclosed in the literature ZL200710090821.9 and the literature ZL201010294407.1. The smell is not easy to migrate, but these products generally have the problem of low light-initiating efficiency. The inventor also discloses a macromolecular benzophenone derivative photoinitiator product in the patent ZL201010294407, which also has a problem of slightly lower activity. If a macromolecular benzophenone derivative photoinitiator is less reactive than benzophenone, although it can be used to maintain the curing speed of the formulation by increasing the amount, the effect is limited; excessive amount will give the cured film. Brought adverse effects: reduced mechanical properties, etc. In addition, some macromolecular benzophenone derivatives have complicated manufacturing processes, are difficult to scale, and have no practical value.

It can be seen that the photoinitiator is highly reactive, has good solubility in the coating formulation, has a very low odor of the cured coating, and has a tendency to migrate and be dissolved much lower than most existing benzophenones and the like. There is a real need.

Summary of the invention

The inventors have surprisingly discovered a compound that meets the above requirements, namely (4-phenylbenzoyl)benzoic acid. ester. The effective group properties of such compounds ensure that they have high initiating activity, polyfunctionalization allows them to maintain a relatively high effective weight per unit weight, and their core groups make them have good solubility and low in photopolymerizable compositions. Mobility.

The present invention provides a compound of formula I,

among them,

G is a residue of a polyhydroxy compound, the number of hydroxyl groups in the polyhydroxy compound is an integer n, and 2≤n≤6; x ₁ is a positive integer, and 2≤x ₁ ≤n, and x ₂ is nx ₁ ;

A is an oxygen atom or A is independent of each other

or

Group of which:

One of R ¹ and R ² represents a hydrogen atom, and the other represents a hydrogen atom, a methyl group or an ethyl group;

a is 1 or 2; b is 4 or 5; y is an integer from 1 to 30;

R is a hydrogen atom, a C ₁ -C ₁₂ alkyl acyl group, an aryl acyl group, or a C ₂ -C ₄ conjugated enoyl group.

The invention also provides a photoinitiator comprising at least one compound of formula I. In addition, the invention also provides the use of a compound of formula I as a photoinitiator.

In view of convenience and economy, a plurality of compounds conforming to the definition of Formula I are often used in practice. Accordingly, the present invention also provides a photoinitiator composition characterized in that the composition consists of two or more compounds of the formula I in any ratio.

Further, the present invention provides a photopolymerizable composition comprising the following components:

a polymerizable component comprising at least one ethylenically unsaturated monomer or oligomer;

A photoinitiator of the invention.

The present invention also provides a method of curing the photopolymerizable composition of the present invention, that is, coating the photopolymerizable composition on a substrate and placing it under light irradiation, especially under ultraviolet radiation. The coating is cured.

In addition to the compound of formula I, one or more mixtures of other types of known photoinitiators, as well as additives which improve the properties of the composition, may be included in the composition; known photoinitiators are available from IGM Resins. Omnipol BP, Omnipol TX, etc.; as a polymerization promoter, for example, polyethylene glycol bis(p-dimethylaminobenzoic acid) ester, Cytec P115. Additives such as matting agents, antifoaming agents, leveling agents and the like to the composition can adjust the properties of the composition.

The photoinitiator of the present invention is used in an amount of 0.1-15% by weight of the composition, and usually it is 1-10%. Play a good photopolymerization.

The prepared photopolymerizable composition can be designed to be used on various substrate surfaces, such as paper, wood, plastic, metal, and coated and irradiated with light in a manner commonly used by those skilled in the art to complete curing. process. The 2-(4-phenylbenzoyl)benzoate compound provided by the invention overcomes the defects of low stimulating activity and difficulty in production of benzophenone and other existing photoinitiators, and has extremely low odor and ultraviolet ray. The curing formula has the advantages of high solubility, migration and tendency to be dissolved by the external medium; the photo-curing experiment results show that the photo-initiated activity per unit weight is almost equivalent to benzophenone itself, and its reactivity is significantly higher than that of commonly used diphenyl. A ketone substitute, such as the product of the comparative examples.

detailed description

For convenience, the 4-phenylbenzoylphenyl group of the compound of the formula I of the present invention is referred to as a photocurable effective group, and is bonded to (A)x ₁ -G-(AR)x via a carbonyl group (-CO-). _On A of ₂ , and (A) x ₁ -G-(AR)x _{2 is} the core of the compound.

In the compounds of formula I of the present invention, -CO-A- attached to 4-phenylbenzoylbenzene may be attached to any position of the phenyl group, for example, ortho-position with 4-phenylbenzoyl, Bit or alignment.

In the compounds of formula I of the invention, the specific A is an oxygen atom or a representative formula

a group; more specific A represents an oxygen atom,

or

a group wherein one of R ¹ and R ² represents a hydrogen atom, the other represents a hydrogen atom, a methyl group or an ethyl group; a is 1 or 2; b is 4 or 5; and y is an integer from 1 to 30;

G is a residue of a polyhydroxy compound, the number of hydroxyl groups in the polyhydroxy compound is an integer n, and 2≤n≤6; x ₁ is a positive integer, and 2≤x ₁ ≤n, and x ₂ is nx ₁ ;

R is a hydrogen atom, a C ₁ -C ₁₂ alkyl acyl group, an aryl acyl group, or a C ₂ -C ₄ conjugated enoyl group.

In the compound of the formula I of the present invention, since x ₁ may be an integer greater than or equal to 2, a plurality of -A- groups are present in this case, and these groups are independent of each other, that is, they may be the same or different, wherein The values of a, b, and y may also be the same or different; when x ₁ = n, x ₂ =0.

The core (A) x ₁ -G-(A) x ₂ group of the compounds of the invention has a significant effect on the properties of the compound. According to the definition of the compound of the formula I according to the invention, the (A) x ₁ -G-(A)x ₂ group contains one or more polyether and/or polyester segments of low degree of polymerization, which makes the compound It is often in a liquid state and helps it dissolve in the coating formulation. The molecular weight of the group (A) x ₁ -G-(A)x ₂ is not more than 2,000, and the excessively high molecular weight causes a low content per unit weight of the photoinitiator.

Preferably G is ethylene glycol, propylene glycol, butanediol, glycerol, trimethylolpropane, ditrimethylolpropane, pentaerythritol The residue of an alcohol or dipentaerythritol.

In the present specification, "a residue of a polyhydroxy compound" or "a residue of an alcohol" means a group remaining after the polyol or the alcohol loses one or more hydroxyl groups. For example, the residue of HOCH ₂ CH ₂ OH is HOCH ₂ CH ₂ - or -CH ₂ CH ₂ -. In the polyhydroxy compound or alcohol, other functional groups may be contained in addition to the hydroxyl group as long as these functional groups do not substantially adversely affect the synthesis or use of the compound of the present invention.

When x _{1 is} smaller than the number n of hydroxyl groups contained in the polyhydroxy compound G, the compound of the present invention contains a free hydroxyl group or these free hydroxyl groups are esterified. There is no particular restriction on the nature of the ester thus obtained, including lower molecular weight C ₁ -C ₁₂ fatty acid esters, C ₂ -C ₄ enoates, examples of such esters including acetates, propionates , butyrate, valerate or acrylate.

When testing the compounds of the present invention prepared in the following examples, the numbers a, b and y in the above formula may not be integers, since in the preparation of the compounds, when the raw materials used are not In the case of a single compound, the product obtained is a mixture of several compounds of the formula (I). Of course, a, b and y are integers for each individual molecule of the product, and a single compound can also be isolated separately, and those skilled in the art will appreciate that when a single polyol is used as the starting material A single pure compound can be obtained, but in practical applications, a mixture of different polymerization degrees of these polyhydroxy compounds is often used.

The compound of the present invention is obtained by reacting, for example, 2-(4-phenylbenzoyl)benzoic acid of the formula II or 3-(4-phenylbenzoyl)benzoic acid of the formula III with a core compound of the formula IV. The preparation is carried out, and A and G in the core compound are defined as A and G in the compound of the formula I, x = x ₁ + x ₂ .

(HA) _x -G (IV)

The esterification reaction is preferably carried out in the presence of a solvent, and the nature of the solvent is not critical to the present invention as long as it does not adversely affect the reagent or reaction. Suitable solvents include: alkanes such as cyclohexane; aromatic hydrocarbons such as benzene, toluene or xylene.

The esterification reaction is selected in an acidic catalyst such as a sulfonic acid (for example p-toluenesulfonic acid or methanesulfonic acid), a mineral acid (such as sulfuric acid, hydrochloric acid or polyphosphoric acid) or a Lewis acid (for example boron trifluoride or organic titanate). In the presence of.

The temperature of the esterification reaction can be varied within a relatively wide range depending on the conditions of the reaction and the nature of the reagents and the solvent, as long as the temperature is high enough to remove water generated during the reaction to ensure completion of the reaction. We find that it is usually close It is most convenient to carry out the reaction at the reflux temperature of the reaction mixture. The time required to complete the reaction varies widely, depending on the reaction temperature. Under the above optimum conditions, usually only 2 to 20 hours of reaction is required.

When x _{1 is} smaller than the number n of hydroxyl groups contained in the polyhydroxy compound G, the above esterified product contains a free hydroxyl group which is esterified with another having a carboxylic acid group. These acids include acetic acid, butyric acid, acrylic acid or methacrylic acid. The esterification is carried out by the same process as the above esterification reaction.

After completion of the reaction, it may be subjected to a post-treatment by a usual method, for example, washing the mixture with water and/or alkali water, drying, and then evaporating the solvent under reduced pressure to give a product.

The compounds of the invention are particularly suitable for use as photoinitiators, for example as photoinitiators in photocurable varnishes or inks. However, they can also be used as photoinitiators in many other photopolymerizable compositions at levels ranging from 0.1% to 15% by weight of the total composition.

Photocurable compositions employing the compounds of the present invention typically comprise at least one photocurable monomer and/or oligomer, a compound of the invention, and optionally a reactive diluent. In the case of printing inks, the composition also includes a colorant, i.e., a pigment. The photocurable monomer or oligomer is preferably an ethylenically unsaturated compound, typically an acrylate oligomer or an acrylate monomer. Suitable acrylate oligomers include: aliphatic or aromatic acrylate urethanes, polyether acrylates, polyester acrylates and epoxy acrylates (e.g., external bisphenol A epoxy acrylate). Suitable acrylate monomers include: hexanediol diacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, polyether acrylate (eg ethoxylated) Trimethylolpropane triacrylate, glycerol propoxy triacrylate, ethoxylated pentaerythritol tetraacrylate, and epoxy acrylate (such as Cytec's Ebecryl 500), and diol diacrylate ( For example, tripropylene glycol diacrylate).

Meanwhile, the photopolymerizable composition of the present invention preferably contains at least one synergist such as an amino acrylate or a p-dimethylamino benzoate. In the case of printing inks, the synergist is preferably p-dimethylaminobenzoate, and in the case of varnish, the synergist is preferably an amino acrylate. Some inks, such as those used in flexographic printing applications, may contain two different types of synergists as described above.

The amount of photocurable monomer or oligomer, photoinitiator, synergist, and optional colorant will vary depending on the type of varnish or ink, the particular equipment used for coating, and the application.

When used as a photoinitiator in varnishes or inks, the compounds of formula I generally comprise, in addition to the ingredients mentioned above, pigments, waxes, stabilizers and rheological aids.

The invention is further illustrated by the following non-limiting examples. In the structural formulas listed in the examples, n represents the degree of polymerization, which can be roughly derived from the molecular weight of the compound, and the values of a plurality of n in the same structural formula may be different.

Comparative Example 1

179.2 g (0.7 mole) of 4-carboxymethoxybenzophenone and 87.5 g (0.35 mole) of polytetrahydrofuran (average molecular weight 250) were placed in 2500 ml of toluene containing 3.0 g of p-toluenesulfonic acid catalyst for azeotropic reflux. 11 hours. The solution was then washed twice with 500 ml of 0.1 M aqueous sodium hydroxide solution and twice with 500 ml of deionized water. The solution was then dried by azeotropy and all solvents were removed under vacuum using a rotary evaporator to afford 244.6 g of pale yellow liquid.

Comparative Example 2

In a 500 ml four-necked flask, 100 g (0.5 mol) of polyethylene glycol 200, 82.5 g (1.0 mol) of methyl benzoylbenzoate and 8 g of sodium methoxide were added, and the mixture was heated to 130 ° C and stirred for 8 hours while stirring. Recovery of methanol. After cooling, the mixture was washed with water, and the water was evaporated under reduced pressure to give 180 g of pale-yellow product, bis benzophenone benzoic acid, polyethylene glycol 200 (mixture of n=4-10 compound in the formula VI), with a total content of 98.15%. , the yield is 97.4%,

Example 1

Preparation of 2-(4-phenylbenzoyl)benzoic acid:

Add 40g (0.3mol) of aluminum trichloride and 80ml of 1,2-dichloroethane to a 250ml four-necked bottle; stir, cool with a cooling tank; connect hydrogen chloride absorption device; add phthalic anhydride 20g (0.135mol), temperature control At -10 ° C - 0 ° C.

27.1 g (0.176 mol) of biphenyl was dissolved in 60 ml of dichloroethane and added dropwise to the above reaction liquid, and the reaction temperature was maintained between -5 ° C and 0 ° C, and the mixture was stirred at this temperature for 2 hours.

Add 50ml of concentrated hydrochloric acid to 100ml four-necked bottle, water 100ml, cool down to 0 °C in ice bath, add the above reaction droplets to hydrochloric acid solution, keep stirring between 25 °C and 40 °C for 1 h, then cool down to -10 °C , filtered; drained; filter cake washed with 2% sodium hydroxide water 300ml for 2h, drained; wet product washed with 5% hydrochloric acid aqueous solution 300ml for 2h, filtered and dried, white powder, weight 27.9g, yield 68.4% .

HPLC analysis of 98.8%, melting point: 226.9-228.5 ° C; elemental analysis C ₂₀ H ₁₄ O ₃ : C 79.40% (theoretical value 79.46%); H 4.80% (theoretical value 4.67%).

Example 2

Preparation of 3-(4-phenylbenzoyl)benzoic acid:

25.5g (0.21mol) of aluminum trichloride and 60ml of 1,2-dichloroethane were added to a 250ml four-necked bottle; stirred, cooled with tap water; connected to a hydrogen chloride absorption unit; 20.1g of isophthaloyl chloride was added (0.1 Mol), the temperature is controlled between 0 ° C and 5 ° C. 15.5 g (0.1 mol) of biphenyl was added in portions to maintain the reaction temperature between 0 ° C and 5 ° C, and the temperature was kept at this temperature for 6 hours.

Add 50ml of concentrated hydrochloric acid to 100ml four-necked bottle, water 100ml, cool down to 0 °C in ice bath, add the above reaction droplets to hydrochloric acid solution, keep stirring between 25 °C and 40 °C for 1 h, then cool down to -10 °C , filtered; drained; the filter cake was washed with 2×30 ml of water and drained; the wet product was an off-white powder after drying, weighing 27.8 g, yield 92%.

HPLC analysis of 3-(4-phenylbenzoyl)benzoic acid content 98.1%, melting point: 199.5-207 ° C; elemental analysis C ₂₀ H ₁₄ O ₃ : C 79.35% (theoretical value 79.46%); H 4.76% ( The theoretical value is 4.67%).

Example 3 Preparation of polytetrahydrofuran bis[2-(4-phenylbenzoyl)benzoic acid] ester

In a 500 ml four-necked flask, 30.3 g (0.1 mol) of Compound II, 12.5 g (0.05 mol) of polytetrahydrofuran (average molecular weight of 250) and 0.86 g of p-toluenesulfonic acid catalyst were placed in 200 ml of toluene for azeotropic reflux for 48 hours. The reaction solution was washed twice with 50 ml of a 0.1 M aqueous sodium carbonate solution and then twice with 50 ml of deionized water. Then, the solution was refluxed, and water was separated by a water separator, toluene was removed by distillation under reduced pressure, and the unreacted compound II was removed by column chromatography using petroleum ether/ethyl acetate. When the eluent was petroleum ether / ethyl acetate = 2:1, the title product was obtained, and the solvent was distilled under reduced pressure to give 28.7 g of a yellow viscous material with a yield of 67.1%. HPLC analysis results: the total target product content was 99.0%, and the results of HPLC-MS analysis are shown in Table 1.

Table 1 Liquid chromatography-mass spectrometry analysis results

In the table

Example 4 Preparation of polytetrahydrofuran bis[2-(4-phenylbenzoyl)benzoic acid] ester

According to the procedure of Example 3, the raw material polytetrahydrofuran (average molecular weight 250) was replaced with polytetrahydrofuran (average molecular weight of 1000) to obtain a pale yellow viscous liquid in a yield of 82%, and the HPLC analysis showed that the target content was 98.0% in total.

Example 5 Preparation of Polyethylene Glycol 400 Di[2-(4-Phenylbenzoyl)benzoic Acid] Ester

In a 1000 ml four-necked flask, 30.3 g (0.1 mol) of compound II, 20.0 g (0.05 mol) of polyethylene glycol (average molecular weight of 400) and 0.86 g of p-toluenesulfonic acid were placed in 200 ml of toluene for azeotropic reflux for 48 hours. The reaction solution was washed twice with 100 ml of a 5% aqueous sodium carbonate solution and twice with 100 ml of deionized water. It was then dried over 5 g of anhydrous sodium sulfate overnight, filtered, and then evaporated to remove toluene to afford 46.9 g of a yellow viscous liquid, yield 93.2%. HPLC analysis results: the target content was 98.0% in total. ¹ H-NMR: 4.66 ppm (m, 21.8H, OCH ₂ CH ₂ O); 7.41 - 8.31 ppm (m, 26H, ArH).

Example 6 Preparation of Polyethylene Glycol 600 Di[2-(4-Phenylbenzoyl)benzoic Acid] Ester

According to the process of Example 5, wherein the raw material polyethylene glycol (average molecular weight of 400) was replaced by polyethylene glycol (average molecular weight of 600) to obtain a pale yellow viscous liquid, the yield was 90%, and the HPLC analysis result: total target content 98.2%.

¹ H-NMR: 4.66 ppm (m, 32H, OCH ₂ CH ₂ O); 7.41 - 8.31 ppm (m, 26H, ArH).

Example 7 Preparation of Polyethylene Glycol 800 Di[2-(4-Phenylbenzoyl)benzoic Acid] Ester

According to the process of Example 5, the raw material polyethylene glycol (average molecular weight of 400) was replaced by polyethylene glycol (average molecular weight of 800) to obtain a pale yellow viscous liquid with a yield of 89%. HPLC analysis results: total target content 97.6%.

¹ H-NMR: 4.66 ppm (m, 44H, OCH ₂ CH ₂ O); 7.41 - 8.31 ppm (m, 26H, ArH).

Example 8 Preparation of diethylene glycol bis[2-(4-phenylbenzoyl)benzoic acid] ester

In a 250 ml four-necked flask, 28.5 g (0.09 mol) of compound II, 5 g (0.047 mol) of diethylene glycol and 0.8 g of p-toluenesulfonic acid were placed in 100 ml of toluene for azeotropic reflux for 54 hours. The reaction solution was washed twice with 100 ml of a 0.1 M aqueous sodium carbonate solution and then twice with 100 ml of deionized water. Then, it was dried over anhydrous sodium sulfate overnight, filtered, and the toluene was evaporated under reduced pressure, and the unreacted compound II was removed by column chromatography using petroleum ether / ethyl acetate. When the eluent was petroleum ether / ethyl acetate = 3:1, the desired product was obtained, and after desolvation, 16.0 g of an off-white solid was obtained. HPLC analysis results: the target content was 98.9% in total. ¹ H-NMR: 3.41-3.45 ppm (m, 4H, -CH ₂ OCH ₂ -); 4.11-4.17 ppm (m, 4H, -CH ₂ O-); 7.35 - 8.07 ppm (m, 26H, ArH).

Example 9 Preparation of Triethylene Glycol Di [2-(4-Phenylbenzoyl)benzoic Acid] Ester

In a 250 ml four-necked flask, 28.5 g (0.09 mol) of compound II, 9.13 g (0.047 mol) of tetraethylene glycol and 0.8 g of p-toluenesulfonic acid were placed in 100 ml of toluene for azeotropic reflux for 54 hours. The reaction solution was washed twice with 100 ml of a 0.1 M aqueous sodium carbonate solution and then twice with 100 ml of deionized water. Then, it was dried over anhydrous sodium sulfate overnight. After filtration, toluene was removed under reduced pressure, and the unreacted compound II was removed by column chromatography using petroleum ether/ethyl acetate. When the eluent was petroleum ether / ethyl acetate = 3:1, the desired product was obtained, and after desolvation, 18.4 g of an off white solid was obtained. HPLC analysis results: the target content was 98.0% in total. ¹ H-NMR: 3.42-3.49 ppm (m, 8H, -OCH ₂ CH ₂ O-); 3.49-3.53 ppm (m, 4H, -CH ₂ O); 4.18-4.21 ppm (m, 4H, CH ₂ O -); 7.32 - 8.07 ppm (m, 26H, ArH).

Example 10 Preparation of Ethoxylated Trimethylolpropane Ethyl 2-(4-Phenylbenzoyl)benzoate

In a 250 ml four-necked flask, 27.2 g (0.09 mol) of compound II, 13.5 g (0.03 mol) of ethoxylated trimethylolpropane (average molecular weight of 450) and 0.5 g of p-toluenesulfonic acid catalyst were placed in 100 ml of toluene. Azeotropic reflux was carried out for 54 hours. The reaction solution was washed twice with 100 ml of a 0.1 M aqueous sodium carbonate solution and then twice with 100 ml of deionized water. Then, it was dried overnight with 5 g of anhydrous magnesium sulfate. After filtration, toluene was removed on a rotary evaporator to obtain 38.2 g of a pale yellow viscous liquid, yield 93.8%. HPLC analysis results: the target content was 98.0% in total.

Example 11 Preparation of ethylene glycol bis[3-(4-phenylbenzoyl)benzoic acid] ester

In a 250 ml four-necked flask, 30.2 g (0.1 mol) of compound III, 3.0 g (0.05 mol) of ethylene glycol and 0.8 g of p-toluenesulfonic acid were placed in 100 ml of toluene for azeotropic reflux for 48 hours. The reaction solution was washed twice with 100 ml of a 0.1 M aqueous sodium carbonate solution and then twice with 100 ml of deionized water. It was then dried over anhydrous sodium sulfate overnight, filtered, and the toluene was removed on a rotary evaporator, and the unreacted compound III was removed by column chromatography using petroleum ether/ethyl acetate. When the eluent was petroleum ether / ethyl acetate = 5:1, the desired product was obtained, and the solvent was evaporated to give a white solid (22.6 g, m.p. HPLC analysis results: the target content was 98.5% in total. ¹ H-NMR: 4.71 ppm (s, 4H, -OCH ₂ CH ₂ O-); 7.40-7.70 ppm (m, 16H, ArH); 7.85-7.88 ppm (d, 4H, ArH); 8.00-8.02 (d , 2H, ArH); 8.25-8.27 (d, 2H, ArH); 8.48 (s, 2H, ArH).

Example 12 Preparation of Triethylene Glycol Di[3-(4-Phenylbenzoyl)benzoic Acid] Esters

Substituting compound III for compound II in the manner of Example 9, gave pale yellow wax I-7, yield 65.2%. The melting range was 62.0-68.5 ° C, and the HPLC analysis results showed that the target content was 96.6% in total.

^{1 H-NMR: 3.63-3.65 (d} , 8H, 2-0CH 2 CH 2 O -), 3.80-3.83 (t, 4H, -CH 2 0CH 2 -), 4.47-4.50ppm (t, 4H, -COOCH ₂ ); 7.40-7.70 ppm (m, 16H, ArH); 7.86-7.89 ppm (d, 4H, ArH); 8.00-8.02 (d, 2H, ArH); 8.26-8.28 (d, 2H, ArH); 8.47 (s, 2H, 2ArH).

The sources of the main reagents used in the above experiments are shown in Table 2 below.

Table 2

raw material name	supplier
		Biphenyl	Sinopharm Chemical Reagent Co., Ltd.
Phthalic anhydride	Jiangsu Yingli Technology Development Co., Ltd.
		Isophthaloyl chloride	Beijing Chemical Reagent Company
Aluminum trichloride	Tianjin Jingjin Pesticide Factory
		p-Toluenesulfonic acid	Shanghai Wulian Chemical Factory
PTHF250	INVISTA
		PTHF1000	Aladdin Reagent
Polyethylene glycol 400	Beijing Huayou Chemical Factory
		Polyethylene glycol 600	Beijing Huayou Chemical Factory
Polyethylene glycol 800	Beijing Huayou Chemical Factory
		Ethoxylated pentaerythritol	Tianjin Tianjiao Chemical Co., Ltd.
Propoxylated pentaerythritol	Tianjin Tianjiao Chemical Co., Ltd.

Example 13

Curing performance comparison

The products of the above Examples 3 to 12, and the products obtained in Comparative Examples 1 and 2, respectively, were used as photoinitiators to prepare corresponding UV-curable varnish formulations, in addition to benzophenone and phenylbenzol. The ketone is used as a photoinitiator to form a corresponding UV curable varnish formulation. The formulation of the varnish formulation is shown in Table 3, and a total of twelve varnish preparations A-K were obtained.

table 3

Formula ingredients	Weight percentage (%)
		Photoinitiator	7
Amino acrylate auxiliaries (Ebecryl P115, Cytec)	8
		Epoxy acrylate oligomer (6210G, Changxing Company)	25
Polyfunctional monomer, GPTA (EM2385 glycerol tripropoxylated triacrylate, Changxing)	60

The resulting varnish formulation was applied to a tinplate using a 10 micron bar coater and cured at a speed of 100 meters per minute using a 100 watt/cm medium pressure mercury lamp. Record the number of passes under the lamp required to obtain a good surface and complete cure, and immediately evaluate the odor level: a maximum of 5 and a minimum of 1. The results are shown in Table 4 below.

Table 4

Formulation number	Photoinitiator contained in the preparation	Number of passes required for complete cure	Cured film odor level
				A	Product (I-1) of Example 3.	3	1
B	Product of Example 5 (I-3)	3	1
				C	Product of Example 7 (I-5)	5	1
D	Product of Example 8 (I-6)	2	1
				E	Product of Example 9 (I-7)	4	1
F	Product of Example 10 (I-8)	2	1
				G	Product of Example 12 (I-10)	3	1
H	Comparative Example 1 Product (V)	6	1
				I	Comparative Example 2 Product (VI)	8	1
J	Benzophenone (BP)	3	5
				K	Phenylbenzophenone (PBZ)	2	4

These results indicate that the compound of the present invention at least corresponds to or is close to the curing speed of benzophenone in terms of curing speed, and the curing speed is significantly higher than other benzophenone macromolecular light in Comparative Example 1 or Comparative Example 2. Initiator. All of the compositions in which the product of the examples was a photoinitiator had a lower odor than benzophenone after complete curing. All examples showed similar yellowness after curing.

Claims (16)

1. a compound of formula I

   

   among them:

   G is a residue of a polyhydroxy compound, but G is not a residue of an amine compound containing a nitrogen atom, the number of hydroxyl groups in the polyhydroxy compound is an integer n, and 2≤n≤6; x ₁ is a positive integer, and 2≤x ₁ ≤n, x ₂ is nx ₁ ;

   A is an oxygen atom or A is independent of each other

   

   

   Group of which:

   One of R ¹ and R ² represents a hydrogen atom, and the other represents a hydrogen atom, a methyl group or an ethyl group;

   a is 1 or 2; b is 4 or 5; y is an integer from 1 to 30;

   R is a hydrogen atom, a C ₁ -C ₁₂ alkyl acyl group, an aryl acyl group, or a C ₂ -C ₁₂ conjugated enoyl group.
2. The compound of claim 1 wherein -CO-A attached to the phenyl ring of formula I is in the ortho or meta position of the 4-phenylbenzoyl group.
3. The compound of claim 1 or 2, wherein A represents

   

   Group.
4. The compound of claim 3 wherein A represents

   

   
5. The compound of claim 1 or 2, wherein A represents

   

   Group.
6. The compound of claim 1 or 2, wherein A represents

   

   Group.
7. The compound according to claim 1 or 2, wherein the molecular weight of the residue (A-)x ₁ G-(A)x ₂ is not more than 1200.
8. The compound of claim 7, wherein the residue (A-) x ₁ G-(A) x _{2 has} a molecular weight of not more than 800.
9. The compound according to claim 1 or 2, wherein G is a residue of ethylene glycol, propylene glycol, butylene glycol, glycerol, trimethylolpropane, ditrimethylolpropane, pentaerythritol or dipentaerythritol.
10. A process for the preparation of a compound of formula I according to claim 1 comprising:

    2-(4-Phenylbenzoyl)benzoic acid, 3-(4-phenylbenzoyl)benzoic acid or 4-(4-phenylbenzoyl)benzoic acid with the formula (HA) _x - The compound of G is subjected to an esterification reaction wherein x = x ₁ + x ₂ .
11. A method of preparing a compound of formula I according to claim 10, comprising:

    2-(4-Phenylbenzoyl)benzoic acid, 3-(4-phenylbenzoyl)benzoic acid or 4-(4-phenylbenzoyl)benzoic acid with the formula (HA) _x - The compound of G is subjected to an esterification reaction, wherein x = x ₁ + x ₂ ;

    When x _{2 is} greater than or equal to 1; and R is an acyl group, the esterification product of the previous step is further subjected to a second esterification reaction with ROH to give a compound of formula I.
12. Use of a compound of the formula I as claimed in one of claims 1 to 9 as a photoinitiator.
13. A photoinitiator characterized by comprising at least one compound of the formula I as described in one of claims 1-9.
14. A photopolymerizable composition characterized by comprising the following components:

    a polymerizable component comprising at least one ethylenically unsaturated monomer or oligomer;

    The photoinitiator of claim 13.
15. The photopolymerizable composition of claim 14 which is a varnish or printing ink.
16. A method of curing a photopolymerizable composition comprising applying the photopolymerizable composition of claim 13 or 14 to a substrate and then exposing it to ultraviolet radiation to complete the coating.