JP2018052873A - Novel compound, photopolymerization initiator and polymerizable liquid crystal composition - Google Patents

Abstract

ここで、一般式（ｉ）中におけるＲ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５、Ｒ^６、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０の分子量の総和は１５以上１７５以下である。
【選択図】 なしThe present invention provides a novel compound useful as a photopolymerization initiator which is less volatile in a liquid crystal composition and has an excellent curing ability. In addition, a polymerizable liquid crystal composition using the compound and a polymer-stabilized liquid crystal display element obtained using the polymerizable liquid crystal composition are provided.
The present invention provides a compound represented by the general formula (i).

Here, the sum of the molecular weights of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ in the general formula (i) is 15 or more and 175 or less. .
[Selection figure] None

Description

  The present invention relates to a novel compound, a photopolymerization initiator using the compound, and a polymerizable liquid crystal composition containing the compound.

Liquid crystal materials are generally used in flat panel displays such as televisions, monitors, mobile phones, smartphones, and tablet terminals. For television applications, the n-type liquid crystal material exhibiting negative dielectric anisotropy is used because the VA method is currently mainstream. Further, a small amount of a polymerizable compound of less than about 1% by mass is added to the n-type liquid crystal material, and cured by UV light, thereby forming protrusions at the liquid crystal material-alignment film interface in the liquid crystal element and inducing pretilt. PSA (polymer-stained alignment) liquid crystal displays have been put into practical use (for example, Patent Document 1).
Furthermore, a display (polymer stabilized liquid crystal display) in which a response speed is improved by forming a three-dimensional polymer network in the liquid crystal element by increasing the addition amount of the polymerizable compound has been reported (Patent Document 2). . When obtaining such a liquid crystal element, it is necessary to add a photopolymerization initiator in order to quickly cure the polymerizable compound.

  Conventionally, for example, Irgacure 651 (manufactured by BASF) is widely used as a photopolymerization initiator added to a liquid crystal material (Patent Documents 2 to 5). However, the photopolymerization initiator has a drawback that it easily volatilizes during liquid crystal dropping injection (ODF process) or dropping injection with an ink jet machine. When volatilization of the polymerization initiator occurs, the concentration distribution of the compound occurs in the liquid crystal element and unevenness occurs, or the display reliability of the liquid crystal display decreases due to the remaining polymerizable compound. Then, the photoinitiator which anticipated the fall of volatility and the affinity improvement to liquid crystal material by introduce | transducing frame | skeleton similar to a liquid crystal compound is proposed (patent document 6).

JP 2012-219270 A WO2015 / 122457 JP 2006-145992 A JP 2010-122712 A US91115308B2 publication JP-A-11-181010

  In general, the ability of a photopolymerization initiator to polymerize a polymerizable compound (referred to as curing ability for convenience) tends to be inversely correlated with the molecular weight. This is because when the molecular weight of the photopolymerization initiator is increased, the rate of movement of the generated radicals is lowered, so that the curing rate of the polymerizable compound is lowered.

  When the curing rate of the polymerizable compound is lowered, the response speed of the polymer-stabilized liquid crystal display element is deteriorated, so that the advantages of the display element are damaged. For example, the photopolymerization initiator described in Patent Document 6 has a low curing ability and cannot meet the high-speed response required for recent polymer-stabilized liquid crystal display elements.

  On the other hand, Irgacure 651 (manufactured by BASF) has a molecular weight of 256, and the molecular weight is too low as a constituent component of a general liquid crystal composition, which is a problem in application as a photopolymerization initiator for liquid crystal materials. It was.

  The present invention provides a novel compound useful as a photopolymerization initiator that is not easily volatilized in a liquid crystal composition and has excellent curing ability.

  In addition, a polymerizable liquid crystal composition using the compound and a polymer-stabilized liquid crystal display device having a high-speed response are provided.

  While paying attention to the high curing ability of Irgcure 651, the present inventors have repeatedly studied the influence of the structural characteristics on various characteristics of the polymer-stabilized liquid crystal display element. As a result, the present inventors have found a novel compound useful as a photopolymerization initiator that can withstand practical use even in polymer-stabilized liquid crystal display devices that require high response speed and display reliability in recent years.

  That is, the present invention relates to the general formula (i)

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, a fluorine atom, a chlorine atom, or a carbon atom. An alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms. 1 or two or more non-adjacent —CH ₂ — present in each group are each independently —O—, —S—, —CO—, —COO—, —OCO—, — CO-S-, -S-CO-, -O-CO-O-, -CO-NH-, -NH-CO-, -CH = CH-COO-, -CH = CH-OCO-, -COO- CH = CH-, -OCO-CH = CH-, -CH = CH-, -CF = CF- May be replaced by -C≡C-, also one or two or more hydrogen atoms present in each group may be substituted by a fluorine atom or a chlorine atom, independently,
The total molecular weight of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ is 15 or more and 175 or less,
A ¹ and A ² each independently represents an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms. ).

  When the compound of the present invention is used with a photopolymerization initiator for a liquid crystal material, it is difficult for volatilization in a liquid crystal dropping injection process or the like to occur, and thus problems due to volatility can be suppressed as in conventional photopolymerization initiators. Also. Since it has a high curing ability, a polymer-stabilized liquid crystal display element with high-speed response can be produced.

  The compound of the present invention has a structure represented by the general formula (i). The structure is characterized in that a specific substituent is bonded to the phenyl group with respect to a skeleton structure containing two phenyl groups. With such a structure, the compound of the present invention has a molecular weight and molecular structure design close to those of widely used liquid crystal materials. For this reason, it is presumed that the compound of the present invention exhibits high compatibility with the liquid crystal composition while maintaining the high curing ability derived from the skeleton structure, and hardly causes volatilization from the liquid crystal composition.

In the general formula (i), the total molecular weight of the groups represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ is 15 or more and 175 or less. It is. This is because when the molecular weight of the compound represented by the general formula (i) is less than 15, the polarity is large and the affinity with the liquid crystal composition is lowered, and when it exceeds 175, the curing ability is lowered. The lower limit of the total molecular weight is preferably 12 or more, more preferably 24 or more, further preferably 40 or more, and the upper limit is preferably 175 or less, and is 150 or less. More preferably, it is more preferably 125 or less, and particularly preferably 100 or less.

In general formula (i), there is a double bond in the molecule of the group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ^10. Then, there exists a possibility that hardening capability may fall, and also introduction | transduction of a carbonyl group or a nitrogen atom has a possibility of increasing the polarity of a compound and reducing solubility. Therefore, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are a fluorine atom, a chlorine atom, an alkyl group having 1 to 10 carbon atoms, a carbon atom A cycloalkyl group having 3 to 10 carbon atoms or an alkoxy group having 1 to 9 carbon atoms, or one or two or more non-adjacent —CH present in the alkyl group, cycloalkyl group or alkoxy group _2- is preferably a group independently substituted by -O-, -CO-, -COO-, -OCO- or -O-CO-O-, and is preferably a fluorine atom, a chlorine atom or a carbon atom having 1 to 10 carbon atoms. More preferably, an alkyl group having 3 to 10 carbon atoms, or an alkoxy group having 1 to 9 carbon atoms, an alkyl group having 1 to 6 carbon atoms, and a cycloalkyl having 3 to 6 carbon atoms. Group, or, more preferably an alkoxy group having 1 to 5 carbon atoms, an alkyl group having 2 to 5 carbon atoms, or, particularly preferably an alkoxy group having 2 to 5 carbon atoms. In the general formula (i), at ^{least one} of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ is a substituent, In consideration of availability, at least one of R ² , R ³ , R ⁴ , R ⁷ , R ⁸ and R ⁹ is preferably a substituent, and among R ² , R ³ , R ⁷ and R ⁸ more preferably 1 or more is a substituent, more preferably more than one of R ³ and R ⁸ is a substituent, it is particularly preferred R ³ and R ⁸ are both substituents. The total number of substituents contained in R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ is preferably 2 or more and 6 or less, The number is preferably 2 or more and 4 or less. The substituents contained in R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are preferably all the same for ease of production. . In particular, R ³ and R ⁸ are preferably the same substituent.

When substituents are present at the 2-position and 6-position of the benzene ring in the general formula (i), there is a concern that the curing ability may be lowered. Therefore, R ¹ , R ⁵ , R ⁶ , and R ¹⁰ are preferably hydrogen atoms.

In general formula (i), R ³ and R ⁸ may be a hydrogen atom, and in this case, one or more of R ² , R ⁴ , R ⁷ and R ⁹ are preferably substituents. .

  The molecular weight of the compound represented by the general formula (i) is preferably 280 or more as a lower limit, more preferably 300 or more, further preferably 320 or more, and the upper limit is 450. Or less, more preferably 400 or less, and even more preferably 370 or less.

In the general formula (i), A ¹ and A ² each represent an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms. In A ¹ and A ² , if there is a double bond in the molecule, there is a concern that the curing ability is lowered, and therefore an alkyl group having 1 to 5 carbon atoms is preferable.

  As the compound represented by the general formula (i), a compound represented by the following general formula (Ia), (Ib) or (Ic) is more preferable.

(Wherein R ¹¹ and R ¹² each independently represents an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms, and R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably each independently an alkyl group having 1 to 6 carbon atoms, ¹⁷ , R ¹⁸ , R ¹⁹ and R ²⁰ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably each independently an alkyl group having 1 to 6 carbon atoms, A ¹¹ and A ¹² each independently represents an alkyl group having 1 to 5 carbon atoms.)
In consideration of easiness of synthesis, specific examples of preferable compounds are shown below. However, the present invention is not limited to these.

(In the formula, R ²¹ and R ²² each independently represent an alkyl group having 2 to 6 carbon atoms or an alkoxy group having 2 to 5 carbon atoms, and A ²¹ and A ²² each independently represent 1 carbon atom. To 2 alkyl groups.)
In the present invention, the compound represented by the general formula (Id) can be produced as follows. Moreover, the compound represented by general formula (i) other than the compound represented by general formula (Ie) or (If) can be normally manufactured according to the same method. Of course, the spirit and scope of the present invention are not limited by these production examples.
(Production Example) Method for Synthesizing Compound Represented by General Formula (Id)

  Benzaldehyde (S-1) can be condensed to obtain benzoin (S-2).

The reagent to be used is not particularly limited as long as the reaction proceeds suitably, but it is preferable to use a cyanide salt alone or to use an N-alkylthiazolium salt treated with a base. Examples of the cyanide salt include sodium cyanide and potassium cyanide. Examples of the thiazolium salt include thiamine and 3-benzyl-5- (2-hydroxyethyl) -4-methylthiazolium chloride. Examples of the base include triethylamine. The amount used is preferably from 0.01 mol to 1.0 mol, more preferably from 0.05 mol to 0.5 mol, based on benzaldehyde. The solvent to be used is not particularly limited as long as it allows the reaction to proceed suitably, but methanol, ethanol, propanol and a mixture thereof with water are preferable. From the viewpoint of the solubility of the raw materials and the reaction temperature, ethanol or hydrous ethanol is preferable. preferable. Although it will not specifically limit as reaction temperature if it is the temperature which advances reaction suitably, 40 to 70 degreeC is preferable.
Subsequently, the benzyl derivative (S-3) can be obtained by oxidizing benzoin (S-2). As the oxidation reaction, many known oxidation reactions can be used. In consideration of practicality, tetrapropylammonium perruthenate (TPAP) oxidation or 9-azabicyclo [3.3.1] nonane = N— Oxidation using oxyl (Stahl oxidation), oxidation using copper (II) sulfate, or the like can be preferably used.

  Finally, the ketone of the benzyl derivative (S-3) can be reacted with an acetalizing reagent in an acid catalyst to obtain a photopolymerization initiator (Id). As the reagent, trimethyl orthoformate or triethyl orthoformate is preferably used. In that case, it is necessary to use methanol in the case of methylation and ethanol in the case of ethylation as a solvent. As the acid catalyst, sulfuric acid, hydrochloric acid, trifluoroacetic acid and the like can be preferably used. The reaction temperature is not particularly limited as long as it allows the reaction to proceed suitably, but is preferably a temperature from room temperature to reflux of the reaction solvent, more preferably from 40 ° C. to reflux of the solvent.

In each step of the above-described production method, purification can be performed as necessary. Purification methods include chromatography, recrystallization, reprecipitation, adsorption and the like. Specific examples of the purification agent used for chromatography include silica gel, NH ₂ silica gel, alumina and the like. Examples of the solvent used at this time include hexane, toluene, and ethyl acetate. Examples of the solvent used for recrystallization or reprecipitation include hexane, toluene, acetone, ethyl acetate, methanol, ethanol and the like. These solvents may be used alone or in combination as required. As a purification agent used for adsorption, activated carbon or the like can be used. As a solvent used in this case, hexane, toluene, acetone, ethyl acetate, or the like can be used.

  The compound of the present invention is useful as a photopolymerization initiator. The compound of the present invention may be used alone as a photopolymerization initiator, or two or more compounds may be used in combination as a photopolymerization initiator.

  The compound of this invention can be widely used for the same use as the conventional photoinitiator. The compound of the present invention is particularly useful as a photopolymerization initiator used by being added to a liquid crystal composition. According to the polymerizable liquid crystal composition containing the compound of the present invention as a photopolymerization initiator, a high-performance and highly reliable liquid crystal display element can be obtained.

  The polymerizable liquid crystal composition contains a polymerizable compound and a liquid crystal compound in addition to the compound of the present invention. The polymerizable compound is not particularly limited as long as it is photopolymerizable by the action of the compound of the present invention, and a known compound may be used. The liquid crystal compound is not particularly limited, and those known in this technical field may be used.

  Furthermore, the compound, photopolymerization initiator, or polymerizable liquid crystal composition of the present invention can be used for applications other than those described above. For example, the use of pharmaceuticals, agricultural chemicals, polymers, resins, pigments, dyes, cosmetics, foods, inks, pressure-sensitive adhesives, adhesives, printed materials, optical anisotropic bodies or electronic devices can be mentioned.

EXAMPLES Hereinafter, although an Example is given and this invention is further described, this invention is not limited to these Examples. “%” In the compositions of the following examples and comparative examples means “% by mass”. The purity of the compound was analyzed by liquid chromatography (LC) and gas chromatography (GC). The structure of the compound was identified by ¹ H-NMR or high-performance liquid chromatography mass spectrometry (HPLC-MS, the ionization method was electrospray method: ESI).

  Details of each characteristic described in the examples are as follows.

Δn: Refractive index anisotropy at 20 ° C. Δε: Dielectric anisotropy at 20 ° C. η: Viscosity at 20 ° C. (mPa · s)
(Example 1) Production of photopolymerization initiator (I-2)

4-Propylbenzaldehyde (17.0 g), potassium cyanide (2.24 g), ethanol (115 mL) and water (115 mL) were added to the reaction vessel, and the mixture was stirred at 70 ° C. for 7 hours. After cooling to room temperature, water (115 mL) was added, and the mixture was extracted with ethyl acetate. The solvent was distilled off under reduced pressure to obtain benzoyl. Subsequently, benzoyl, copper sulfate (26.0 g), pyridine (20.5 g) and water (10.3 g) were added to the reaction vessel, and the mixture was stirred at 70 ° C. for 2 hours. After cooling to room temperature, the mixture was neutralized with 10% hydrochloric acid and extracted with ethyl acetate. After evaporating the solvent under reduced pressure, the residue was purified by column chromatography and recrystallization to obtain a benzyl derivative. Next, a benzyl derivative, trimethyl orthoformate (10.8 g) and methanol (17 mL) were added to the reaction vessel, and concentrated sulfuric acid (0.50 g) was added at 25 ° C. with stirring. Stir at 50 ° C. for 10 hours. After evaporating the solvent under reduced pressure, the residue was purified by column chromatography to obtain 6.0 g of (I-2).
¹ H-NMR (400 MHz, CDCl ₃ ): 0.90 (t, J = 7.3 Hz, 6H), 1.50-1.67 (m, 4H), 2.55 (t, J = 7.7 Hz) 4H), 3.20 (s, 6H), 7.13 (dd, J = 8.5 Hz, 18.9 Hz, 4H), 7.51 (d, J = 8.4 Hz, 2H), 7.9. (D, J = 8.4 Hz, 2H).
^{HPLC-MS (ESI): m} / z 363 [M + Na +], 379 [M + K +], 404 [M + Na + CH 3 CN +].
Examples 2 to 15 Production of photopolymerization initiators (I-1) to (I-15) Photopolymerization initiators (I-2-a) were synthesized in the same manner as in Example 1. The compound was identified by HPLC-MS (ESI).

(Example 16) Evaluation of photopolymerization initiator (I-2) <Evaluation of volatility>
In general, the relative volatility of a compound is correlated with the retention time at the time of GC measurement. The photopolymerization initiator (I-2) synthesized in Example 1 was subjected to GC measurement, and the retention time was determined. Among the low molecular weight components in the liquid crystal composition, CC-34 is used as a reference material for evaluating volatility.

It was 9.7 minutes when GC measurement of this was performed.

GC measurement conditions: Shimadzu GC-2014, DB-1 manufactured by Column J & W (length 30 m, diameter 0.25 mm × film thickness 0.25 μm), inlet temperature 300 ° C., detector temperature 320 ° C., detection method FID, temperature program 110 ° C. → 10 ° C./min→300° C. (21 minutes hold), linear velocity 58 cm / sec.
<Preparation of liquid crystal composition and creation of polymer stabilized liquid crystal display element>
In the polymer-stabilized liquid crystal display element, the higher the curing ability of the photopolymerization initiator, the more the polymerizable compound cures, and the response fall time (τOFF) decreases. In other words, the smaller the response time, the better the high-speed response, and thus a useful liquid crystal display element.

  Liquid crystal composition containing each compound in the ratio shown below (Δn = 0.102, viscosity η = 16.8, Δε = -3.8) 97.8%, polymerizable compound (RM-1) 2%, and Then, 0.2% of photopolymerization initiator (I-2) was mixed to prepare a polymerizable liquid crystal composition (LCM-1).

Next, a liquid crystal display element was produced. First, a glass cell with ITO having a cell gap of 3 μm was prepared. After applying a polyimide alignment film to the cell, a rubbing alignment process is performed so that the pretilt angle is 1 ° to 2 ° with respect to the normal direction of the substrate surface so that the vertical alignment (homeotropic alignment) of the liquid crystal is obtained. gave. The polymerizable liquid crystal composition (LCM-1) was injected into the obtained parallel rubbing alignment cell with ITO by a vacuum injection method in a state heated to 60 ° C.

The cell in which the composition was sealed was taken out, and the inlet was sealed with a sealing agent 3026E (manufactured by Three Bond Co.). Ultraviolet rays having an irradiation intensity of 20 mW / cm ² through an ultraviolet cut filter L-37 (manufactured by Hoya Candeo Optronics) were irradiated at 25 ° C. for 600 seconds. Thus, the polymerizable compound in the polymerizable liquid crystal composition was cured to obtain a VA mode liquid crystal display element in which a polymer network was formed in the cell. When the prepared cell is placed between two polarizing plates arranged in crossed Nicols, it turns black, and even if the cell is rotated in the azimuth direction, the dark field does not change, and the optical axis direction of the polymer network and the liquid crystal alignment easy axis direction are Confirmed to be in the same direction.

In order to confirm the high-speed response of the liquid crystal display element, a rectangular wave of 60 Hz was applied and the response time (fall time, τOFF) was measured.
(Comparative Example 1)
In order to examine the volatility of a commercially available photopolymerization initiator Irgacure 651 (manufactured by BASF), GC measurement was performed. Further, a liquid crystal display element was prepared after preparing a polymerizable liquid crystal composition (LCM-C1) in the same manner as in Example 1 except that the Irgacure 651 was used in place of the photopolymerization initiator (I-2). Time was measured.
(Comparative Example 2)
In order to examine the volatility of a known photopolymerizable initiator (PI-1 described in Patent Document 6), GC measurement was performed. Furthermore, a liquid crystal display element was prepared after preparing a polymerizable liquid crystal composition (LCM-C2) in the same manner as in Example 1 except that the PI-1 was used instead of the photopolymerization initiator (I-2). The response time was measured.

The results of each measurement are shown below.

  By comparing Example 16 and Comparative Example 1, it can be confirmed that the photopolymerization initiator of the present invention is less volatile than the commercially available photopolymerization initiator Irgacure 651 and less volatile than CC-34. It was. Actually, the display quality of the liquid crystal display element prepared in Example 16 was good, and no unevenness was observed. On the other hand, the liquid crystal display element produced by adding the photoinitiator of this invention by comparing Example 16 and Comparative Example 2 is faster than the liquid crystal display element produced using said PI-1. It turns out that it is excellent in responsiveness.

Claims (9)

Formula (i)

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, a fluorine atom, a chlorine atom, or a carbon atom. An alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms. 1 or two or more non-adjacent —CH ₂ — present in each group are each independently —O—, —S—, —CO—, —COO—, —OCO—, — CO-S-, -S-CO-, -O-CO-O-, -CO-NH-, -NH-CO-, -CH = CH-COO-, -CH = CH-OCO-, -COO- CH = CH-, -OCO-CH = CH-, -CH = CH-, -CF = CF- May be replaced by -C≡C-, also one or two or more hydrogen atoms present in each group may be substituted by a fluorine atom or a chlorine atom, independently,
The total molecular weight of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ is 15 or more and 175 or less,
A ¹ and A ² each independently represents an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms. ) A compound represented by In general formula (i), at ^{least one} of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ is independently a fluorine atom, chlorine The compound according to claim 1, which represents an atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. In general formula (i), one or more of R ² , R ³ , R ⁷ and R ⁸ are each independently a fluorine atom, a chlorine atom, an alkyl group having 1 to 6 carbon atoms, or 1 to 5 carbon atoms. The compound according to any one of claims 1 to 2, which represents an alkoxy group of: In general formula (i), one or more of R ³ and R ⁸ each independently represents a fluorine atom, a chlorine atom, an alkyl group having 2 to 6 carbon atoms, or an alkoxy group having 2 to 5 carbon atoms. Item 4. The compound according to any one of Items 1 to 3. The compound according to any one of claims 1 to 4, wherein, in the general formula (i), R ³ and R ⁸ represent the same group.   The photoinitiator containing the compound of any one of Claim 1 to 5.   A polymerizable liquid crystal composition comprising the photopolymerization initiator according to claim 6.   A liquid crystal display device using the polymerizable liquid crystal composition according to claim 7.   Pharmaceuticals, agricultural chemicals, polymers, resins, pigments, dyes, cosmetics, foods, inks, containing or containing the compound according to any one of claims 1 to 7, a photopolymerization initiator or a polymerizable liquid crystal composition, Adhesive, adhesive, printed matter, optical anisotropic body or electronic device.