Acrylic compounds containing fluoropolyether groups

Abstract

According to the present invention, a fluoropolyether group-containing acrylic compound represented by formula (1) has a low refractive index and is capable of forming a transparent composition by being compatibilized with a commonly used photopolymerization initiator.　(1): V1-Rf2-C(=O)-NR1 a[Y2(X2)b']2-a (In the formula, Rf2 represents a divalent perfluoropolyether group that is composed of a perfluoroalkylene group having 1 to 6 carbon atoms and an oxygen atom, while having a number average molecular weight of 500 to 40,000; Y2 represents a (b' + 1)-valent organic group having 1 to 20 carbon atoms; X2 represents a monovalent organic group that contains an acryl group or an α-substituted acryl group, and at least one acryl group or α-substituted acryl group is contained in each molecule on average; R1 represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 8 carbon atoms; V2 represents a hydrogen atom, a fluorine atom or a monovalent group represented by -C(=O)-NR1 a[Y2(X2)b']2-a; a represents 0 or 1; and b' represents an integer of 1 to 10.)

Description

[Technical Field]

[0001] The present invention relates to a fluoropolyether group-containing acrylic compound that has a low refractive index and is compatible with photopolymerization initiators to form a transparent composition. [Background technology]

[0002] Conventionally, polymers containing polymerizable monomers having perfluoroalkyl groups in their side chains, such as fluorine-containing alkyl esters of acrylic acid and fluorine-containing alkyl esters of methacrylic acid, are widely known as fluorine compounds that can be cured by light irradiation, such as ultraviolet light. These fluorine-containing acrylic compounds have been widely explored for use in optical materials, taking advantage of their excellent curing properties by ultraviolet irradiation, high transparency, and low refractive index. For example, Japanese Patent Publication No. 6-136062 (Patent Document 1) describes , including Fluoroacrylic compounds have been shown to be used in anti-reflective coatings, and Japanese Patent Publication No. 5-32749 (Patent Document 2) also shows their use as coating materials for optical fibers.

[0003] On the other hand, when the fluorine content of these fluorine-containing acrylic compounds is increased for purposes such as further lowering the refractive index, the solubility in non-fluorinated organic compounds decreases, and they become insoluble in common photopolymerization initiators, resulting in problems such as the inability to obtain transparent cured products or increased crystallinity leading to loss of transparency. Therefore, it was difficult to obtain transparent cured products with a refractive index below a certain value.

[0004] Under these circumstances, the present inventors have been developing fluorine-containing acrylic compounds, and have proposed, for example, a fluorine-containing curable composition that can be cured with ultraviolet light and form a transparent cured product with a low refractive index, as shown in Japanese Patent Application Publication No. 2006-233172 (Patent Document 3).

[0005] Although these compositions can form a transparent cured product having a low refractive index, on the other hand, there is also a problem that a photoinitiator modified with a perfluoropolyether group has to be separately synthesized for these compositions.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a fluoropolyether group-containing acrylic compound having a low refractive index and capable of forming a transparent composition compatible with a photoinitiator.

Means for Solving the Problems

[0008] As a result of further studies to achieve the above object, the present inventors have found that a fluoropolyether group-containing acrylic compound represented by the following general formula (1) has a low refractive index and is compatible with a general photoinitiator to form a transparent composition, and thus have completed the present invention. V 2 -Rf 2 -C(=O)-NR 1 a [Y 2 (X 2 ) b’ 2-a (1) (In the formula, Rf 2 is a divalent perfluoropolyether group having a number average molecular weight of 500 to 40,000, which is composed of a perfluoroalkylene group having 1 to 6 carbon atoms and an oxygen atom. Y​2 These are independently (b'+1) valence organic groups with 1 to 20 carbon atoms. 2 R is a monovalent organic group that independently contains an acrylic group or an α-substituted acrylic group, and contains, on average, at least one of the acrylic group or α-substituted acrylic group per molecule. 1 V is a hydrogen atom or a monovalent hydrocarbon group having 1 to 8 carbon atoms. 2 is a hydrogen atom, a fluorine atom, or -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ] 2-a This is a monovalent base represented by where a is 0 or 1, and b' is an integer between 1 and 10.

[0009] Accordingly, the present invention provides the following fluoropolyether group-containing acrylic compounds. [1] A fluoropolyether group-containing acrylic compound represented by the following general formula (1). V 2 -Rf 2 -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ] 2-a (1) (In the formula, Rf 2 teeth The following formula [ka] (In the formula, c is an independent integer between 2 and 6 for each unit. d, e, f, g, h, and i are each integers between 0 and 200, so d+e+f+g+h+i=25 to 200. Each of these units may be linear or branched, and each repeating unit shown in parentheses with d, e, f, g, h, and i may be randomly combined.) It is represented number average molecular weight Over 4,400 It is a divalent perfluoropolyether group with a value of 40,000 or less. 2 These independently have 1 to 20 carbon atoms. of( b'+1) value hydrocarbon group X 2 The following structural formulas are independent of each other. [ka] (In the formula, R 2(Independently, is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group; W is a single bond, or a divalent or trivalent hydrocarbon group which may contain one or more selected from ether bonds, ester bonds, and urethane bonds; and n is 1 or 2.) A monovalent organic group containing an acrylic group or an α-substituted acrylic group, and containing, on average, at least one of the acrylic group or α-substituted acrylic group per molecule. 1 V is a hydrogen atom or a monovalent hydrocarbon group having 1 to 8 carbon atoms. 2 is a hydrogen atom, a fluorine atom, or -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ] 2-a This is a monovalent group represented by the formula shown above. a is 0 or 1. b' is an integer from 1 to 10. However, when a=b'=n=1, W in the above structural formula is a divalent hydrocarbon group containing one or more selected from ether bonds, ester bonds, and urethane bonds. [ 2 ] In general formula (1), Rf 2 The following structural formula -CF2CF2O-(CF2CF2CF2O) q -CF2CF2- (In the formula, q is 25 (It is an integer up to 200.) [ka] (In the formula, r is an integer from 1 to 6, C r F 2r O can be linear or branched, s is an integer from 0 to 6, t and u are integers from 1 to 200, and t+u is 25 For integers up to 200, s+t+u is 25 It is an integer up to 200. v is 25 (It is an integer up to 200.) It is selected from the divalent perfluoropolyether groups represented by . [1] The fluoropolyether group-containing acrylic compound described above. [ 3] In general formula (1), R 1 is a hydrogen atom and a is 1. [1] or [ 2] The fluoropolyether group-containing acrylic compound described above. [ 4 ] In general formula (1), Y 2 [1]~[ 3 A fluoropolyether group-containing acrylic compound as described in any of the following. [ka] (In the formula, * is a bond that joins with N, and ** is X) 2 (This is a bonding operation that connects to [another element].) [ 5 ] In general formula (1), X 2 [1]~[ 4 A fluoropolyether group-containing acrylic compound as described in any of the following. [ka] [ 6 ] The fluoropolyether group-containing acrylic compound represented by formula (1) is represented by one of the following formulas [1]~[ 5 A fluoropolyether group-containing acrylic compound as described in any of the following. [ka] (In the formula, X 2 The above is the same. q is 25 An integer up to 200, r is an integer from 1 to 6, C r F 2r O can be linear or branched, s is an integer from 0 to 6, t and u are integers from 1 to 200, and t+u is 33 For integers up to 200, s+t+u is 34 (It is an integer up to 200.) [ 7 ] The refractive index under the conditions of a temperature of 25°C and a wavelength of 589 nm is 1.339 The following is [1]~[ 6 A fluoropolyether group-containing acrylic compound as described in any of the following. [ 8 ] A compound with a uniform appearance is obtained by mixing 100 parts by mass of the fluoropolyether group-containing acrylic compound with 1 part by mass of 2-hydroxy-2-methylpropiophenone or 2-diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide) [1]~[ 7 A fluoropolyether group-containing acrylic compound as described in any of the following. [Effects of the Invention]

[0010] The fluoropolyether group-containing acrylic compound of the present invention has a low refractive index and is compatible with photopolymerization initiators to form transparent compositions. For this reason, the fluoropolyether group-containing acrylic compound of the present invention is useful as a material for fluorine-containing active energy ray curable compositions for optical components and the like. [Modes for carrying out the invention]

[0011] The fluoropolyether group-containing acrylic compound of the present invention is characterized by being represented by the following general formula (1). V 2 -Rf 2 -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ] 2-a (1) (In the formula, Rf 2 It is a divalent perfluoropolyether group with a number average molecular weight of 500 to 40,000, composed of a perfluoroalkylene group having 1 to 6 carbon atoms and an oxygen atom. 2 These are independently (b'+1) valence organic groups with 1 to 20 carbon atoms. 2R is a monovalent organic group that independently contains an acrylic group or an α-substituted acrylic group, and contains, on average, at least one of the acrylic group or α-substituted acrylic group per molecule. 1 V is a hydrogen atom or a monovalent hydrocarbon group having 1 to 8 carbon atoms. 2 is a hydrogen atom, a fluorine atom, or -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ] 2-a This is a monovalent base represented by where a is 0 or 1, and b' is an integer between 1 and 10.

[0012] In this invention, "acrylic compound" is a general term for compounds having an acrylic group or an α-substituted acrylic group, and also includes compounds in which two or more acrylic groups or α-substituted acrylic groups are introduced to the side chains or terminals of various polymers by any means. Furthermore, in this invention, "(meth)acrylate" refers to either or both acrylate and methacrylate, "(meth)acrylic group" refers to either or both an acrylic group and a methacrylic group, and "(meth)acrylic acid" refers to either or both acrylic acid and methacrylic acid.

[0013] The fluoropolyether group-containing acrylic compound of the present invention has a perfluoropolyether group as a group having a low refractive index, an amide bond as a group that improves compatibility with photopolymerization initiators, and an acrylic group or an α-substituted acrylic group. Therefore, it has a low refractive index and can form a transparent composition that is compatible with photopolymerization initiators. Furthermore, it can be used as a material for fluorine-containing active energy curable compositions that can be cured by active energy rays such as ultraviolet rays and electron beams.

[0014] The fluoropolyether group-containing acrylic compound of the present invention must have an amide structure in its structure. The amide structure acts as a hydrogen bond acceptor, and through interaction with hydrogen atoms in the photopolymerization initiator, the compatibility with the photopolymerization initiator is improved. As a result, the compound becomes compatible with the photopolymerization initiator and can form a transparent composition.

[0015] In the above equation (1), Rf 2 Rf is a divalent perfluoropolyether group with a number average molecular weight of 500 to 40,000, composed of a perfluoroalkylene group having 1 to 6 carbon atoms and an oxygen atom. 2 Preferably, the material has 1 to 6 carbon atoms, and especially the following perfluorooxyalkylene structures with 1 to 3 carbon atoms as its main repeating units. -CF2O- -CF2CF2O- -CF(CF3)CF2O- -CF2CF2CF2O- These structures may be single homopolymers or random or block polymers consisting of multiple structures.

[0016] Rf having such a structure 2 For example, the following structure can be cited. [ka] (In the formula, c is an independent integer between 2 and 6 for each unit. d, e, f, g, h, and i are each integers between 0 and 200, so d+e+f+g+h+i=4 to 200. Each of these units may be linear or branched, and each repeating unit shown in parentheses with d, e, f, g, h, and i may be randomly combined.)

[0017] In the above formula, c is an integer between 2 and 6, preferably between 2 and 4, independently for each unit. If c is 1, the amide bond in the compound becomes susceptible to hydrolysis due to the electron-withdrawing properties of the fluorine and oxygen atoms, and decomposition progresses during storage. Therefore, it is preferable that c is an integer between 2 and 6, independently for each unit. Furthermore, d, e, f, g, h, and i are each integers from 0 to 200, preferably d is an integer from 0 to 100, e is an integer from 5 to 100, f is an integer from 5 to 100, g is an integer from 0 to 100, h is an integer from 0 to 100, and i is an integer from 0 to 100, so d+e+f+g+h+i=4 to 200, preferably 10 to 150, and more preferably 30 to 150. In the above formula, each unit may be linear or branched. Furthermore, the repeating units indicated in the parentheses labeled d, e, f, g, h, and i may be randomly combined.

[0018] Rf 2 The number-average molecular weight of the relevant structural part only needs to be within the range of 500 to 40,000, preferably 2,000 to 25,000, and there are no particular limitations on the molecular weight distribution (or degree of polymerization distribution). If the number-average molecular weight is less than 500, the refractive index will increase due to a decrease in fluorine atom content, and if it exceeds 40,000, the decrease in handling properties due to increased viscosity and the decrease in compatibility with polymerization initiators due to the increase in fluorine atom content become significant. In this invention, the molecular weight (or degree of polymerization or number of repeating units) may also be determined as the number-average molecular weight (or number-average degree of polymerization) in polystyrene terms by gel permeation chromatography (GPC) analysis using a fluorine-based solvent as the developing solvent. 1 H-NMR analysis and 19 The number-average molecular weight (or number-average degree of polymerization) can also be calculated from the ratio of characteristic peak intensity between the terminal structure and the main chain structure of the fluoropolyether group-containing acrylic compound based on F-NMR analysis (the same applies hereafter).

[0019] Rf having such a structure 2 A suitable example of this is the following structure: -CF2CF2O-(CF2CF2CF2O) q -CF2CF2- (In the formula, q is an integer between 4 and 200, preferably between 10 and 150.) [ka] (In the formula, r is an integer from 1 to 6, preferably an integer from 2 to 4, C r F 2rO may be linear or branched; s is an integer from 0 to 6, preferably from 1 to 4; t is an integer from 1 to 100, preferably from 5 to 80; u is an integer from 1 to 100, preferably from 5 to 80; t+u is an integer from 2 to 200, preferably from 10 to 150; s+t+u is an integer from 4 to 200, preferably from 10 to 150; v is an integer from 5 to 200, preferably from 10 to 150.

[0020] Rf 2 The most suitable example is the following structure. Generally, Rf 2 The terminal portion is highly reactive due to the electron-withdrawing nature of the fluorine atom and is prone to hydrolysis, but Rf 2 If Rf has the following structure, 2 Since the terminal portion is shielded by a C2F4 group, more preferably a CF(CF3) group, hydrolysis is less likely to occur, and decomposition does not progress even during long-term storage, making it particularly preferable. [ka] (In the formula, r, s, t, u, and v are the same as above.)

[0021] In the above equation (1), R 1 R is a hydrogen atom or a monovalent hydrocarbon group having 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms. Specific examples of monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, and octyl groups, cycloalkyl groups such as cyclohexyl groups, alkenyl groups such as vinyl, allyl, and propenyl groups, aryl groups such as phenyl, tolyl, and xylyl groups, and aralkyl groups such as benzyl and phenylethyl groups. 1 Preferably, the group is a hydrogen atom, a methyl group, or an ethyl group, and particularly preferably a hydrogen atom.

[0022] In the above equation (1), Y 2is independently an organic group having (b'+1) valences with 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, and is preferably (b'+1)-valent hydrocarbon group with 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, which may contain an ether bond. Y 2 Particularly preferred structures of 2 include the following. [Chemical formula] (In the formula, * is a bond connecting to N, and ** is a bond connecting to X 2 and is a bond connecting to X.)

[0023] In the above formula (1), X 2 is independently a monovalent organic group containing an acrylic group or an α-substituted acrylic group, and contains at least 1 acrylic group or α-substituted acrylic group on average in one molecule.

[0024] X 2 Preferably has a structure represented by the following formula. [Chemical formula] (In the formula, R 2 is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, W is a single bond, or a divalent or trivalent hydrocarbon group which may contain one or more selected from an ether bond, an ester bond and a urethane bond, and n is 1 or 2.)

[0025] In the above formula, W is a single bond, or a divalent or trivalent hydrocarbon group which may contain one or more selected from an ether bond, an ester bond and a urethane bond, and examples of the divalent or trivalent hydrocarbon group include groups represented by the following formula. [Chemical formula] (In the formula, * is a bond connecting to Y 2 in the general formula (1), and ** is a bond connecting to an oxygen atom.)

[0026] X 2As for the structure represented by the following formula, it is more preferable. [Chemical formula]

[0027] In the above formula (1), V 2 is a monovalent group represented by a hydrogen atom, a fluorine atom, or -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ) 2-a and is preferably a monovalent group represented by -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ) 2-a . When V 2 is a monovalent group represented by -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ) 2-a , since the composition containing the compound contains at least two or more acrylic groups or α-substituted acrylic groups on average in one molecule, a cured product having a network-like network and excellent mechanical properties can be obtained. Incidentally, when V 2 is a monovalent group represented by -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ) 2-a , in the case of a monovalent group represented by, a plurality of R 1 , Y 2 , X 2 , b', and a may be the same or different from each other.

[0028] In the above formula (1), a is 0 or 1, and preferably 1. In the above formula (1), b' is an integer of 1 to 10, and preferably 1 or 2.

[0029] The fluoropolyether group-containing acrylic compound represented by the above formula (1) is preferably one represented by the following formula. [ka] (In the formula, X 2 q, r, s, t, and u are the same as above.

[0030] As the fluoropolyether group-containing acrylic compound represented by the above formula (1), the one represented by the following formula is particularly preferred. [ka] (In the formula, X 2 ,r,s,t,u are the same as above.

[0031] In an acrylic compound containing a fluoropolyether group represented by general formula (1), for example, V 2 -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ] 2-a The following general formula (2) represents a monovalent group Rf 2 [C(=O)-NR 1 a [Y 2 (X 2 ) b’ ] 2-a ]2(2) (In the formula, Rf 2 , R 1 , Y 2 , X 2 (a and b' are the same as above.) A suitable method for synthesizing fluoropolyether group-containing acrylic compounds represented by the following general formula (3) is, for example, first by: Rf 2 [C(=O)-X 3 ]2(3) (In the formula, Rf 2 The above is the same as X 3 (This is a halogen atom or an unsubstituted or fluorine-substituted alkoxy group.) A fluoropolyether group-containing compound having an acid halide or ester at the end of the molecular chain represented by the following general formula (4) H-NR 1 a [Y 2 [OH] b’ ] 2-a (4) (In the formula, R 1 , Y 2 (a and b' are the same as above.) By amidating the amino alcohol compound represented by [formula], an intermediate alcohol compound containing a fluoropolyether group is obtained.

[0032] Here, X in equation (3) above 3 The hydrogen atoms are halogen atoms, or preferably unsubstituted or fluorine-substituted alkoxy groups having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms. Specifically, examples include halogen atoms such as fluorine, chlorine, and bromine; alkoxy groups such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy, hexyloxy, and octyloxy groups; and fluorine-substituted alkoxy groups such as trifluoromethoxy, 2,2,2-trifluoroethoxy, and 1,1,1,3,3,3-hexafluoroisopropoxy, in which some or all of the hydrogen atoms of these groups are substituted with fluorine atoms.

[0033] Examples of fluoropolyether group-containing compounds having an acid halide or ester at the end of the molecular chain represented by formula (3) above include those listed below. Rf 2 [C(=O)-Cl]2 Rf 2 [C(=O)-F]2 Rf 2 [C(=O)-O-CH3]2 Rf 2 [C(=O)-O-C2H5]2 Rf 2 [C(=O)-O-C3H7]2 Rf 2 [C(=O)-O-C4H9]2 Rf 2[C(=O)-O-C5H 11 ]2 Rf 2 [C(=O)-O-C6H 13 ]2 Rf 2 [C(=O)-O-CF3]2 Rf 2 [C(=O)-O-C2F5]2 Rf 2 [C(=O)-O-CH(CF3)2]2 (In the formula, Rf 2 (This is the same as above.)

[0034] Furthermore, the following are examples of amino alcohol compounds represented by the above formula (4). [ka] [ka] [ka] [ka]

[0035] The reaction ratio between the fluoropolyether group-containing compound represented by formula (3), which has an acid halide or ester at the end of its molecular chain, and the amino alcohol compound represented by formula (4) is preferably such that the amino alcohol compound represented by formula (4) is used in proportion to the total number of moles of acid halide or ester groups in the fluoropolyether group-containing compound represented by formula (3), with a ratio of 1 to 12 times, and particularly 1.2 to 6 times, of the total number of moles of acid halide or ester groups in the fluoropolyether group-containing compound represented by formula (3). If the amount of the amino alcohol compound represented by formula (4) is too small, it may be difficult to obtain the desired fluoropolyether group-containing alcohol compound.

[0036] This amidation reaction is preferably carried out by mixing a fluoropolyether group-containing compound having an acid halide or ester at the molecular chain end represented by formula (3) with an amino alcohol compound represented by formula (4), at a reaction temperature of 0 to 100°C, preferably 0 to 80°C, for 1 minute to 48 hours, and particularly for 10 minutes to 12 hours. If the reaction temperature is too low, the reaction may not proceed sufficiently and may stop, and if it is too high, undesirable side reactions or decomposition of the starting materials may occur.

[0037] The above amidation reaction can be carried out even without a solvent, but it may be diluted with a solvent if necessary. In this case, a widely used organic solvent can be used as the diluent, but it is preferable that the boiling point is above the target reaction temperature and does not inhibit the reaction. Suitable solvents for this purpose include partially fluorinated solvents such as fluorine-modified aromatic hydrocarbon solvents such as m-xylene hexafluoride and benzotrifluoride, and fluorine-modified ether solvents such as methyl perfluorobutyl ether, with m-xylene hexafluoride being particularly preferred. When using a solvent, the amount used is preferably 5 to 2,000 parts by mass, and more preferably 50 to 500 parts by mass, per 100 parts by mass of the fluoropolyether group-containing compound having an acid halide or ester at the molecular chain end represented by formula (3). If the amount is less than this, the dilution effect of the solvent will be weak, and if the amount is too high, the degree of dilution may become too high, which may lead to a decrease in the reaction rate.

[0038] After the reaction is complete, it is preferable to remove any unreacted amino alcohol compounds represented by formula (4) and diluting solvent by known methods such as vacuum distillation, extraction, or adsorption.

[0039] As described above, by amidating a fluoropolyether group-containing compound having an acid halide or ester at the molecular chain terminus represented by general formula (3) with an amino alcohol compound represented by general formula (4), a fluoropolyether group-containing alcohol compound represented by general formula (5) can be obtained. Rf 2 [C(=O)-NR1 a [Y 2 [OH] b’ ] 2-a ]2(5) (In the formula, Rf 2 , R 1 , Y 2 (a and b' are the same as above.)

[0040] Examples of fluoropolyether group-containing alcohol compounds represented by formula (5) are shown below. [ka] [ka] [ka] [ka] (In the formula, Rf 2 (This is the same as above.)

[0041] Next, by introducing a (meth)acrylic group into the fluoropolyether group-containing alcohol compound represented by formula (5) obtained above, the target fluoropolyether group-containing acrylic compound represented by formula (2) can be obtained.

[0042] One method for introducing a (meth)acrylic group into a fluoropolyether group-containing alcohol compound represented by formula (5) is to react the fluoropolyether group-containing alcohol compound represented by formula (5) with an isocyanate compound containing a (meth)acrylic group.

[0043] Examples of isocyanate compounds containing a (meth)acrylic group include those listed below. [ka]

[0044] The isocyanate compound containing (meth)acrylic groups may be charged and reacted in an equimolar or greater amount relative to the total amount of hydroxyl groups in the fluoropolyether group-containing alcohol compound, thereby reacting all the hydroxyl groups. However, it is sufficient to introduce at least 1 mole of (meth)acrylic groups on average per mole of fluoropolyether group-containing alcohol compound, and an excess of hydroxyl groups may be used to prevent the remaining unreacted isocyanate compound containing (meth)acrylic groups. Specifically, if the amount of fluoropolyether group-containing alcohol compound in the reaction system is x moles and the total amount of hydroxyl groups in the fluoropolyether group-containing alcohol compound is y moles, it is desirable that the isocyanate compound containing (meth)acrylic groups be between x moles and 2y moles, and particularly preferably between x moles and 0.6y moles and 1.4y moles. If the amount is too small, there is a high possibility that fluoropolyether group-containing alcohol compounds with no (meth)acrylic groups introduced will remain, and if the amount is too large, it will be difficult to remove the unreacted isocyanate compound containing (meth)acrylic groups.

[0045] Furthermore, the reaction may be carried out after dilution with a suitable solvent as needed. Such solvents are not particularly limited as long as they do not react with the hydroxyl group of the fluoropolyether group-containing alcohol compound or the isocyanate group of the (meth)acrylic group-containing isocyanate compound. Specifically, examples include hydrocarbon solvents such as toluene, xylene, and isooctane; ether solvents such as tetrahydrofuran (THF), diisopropyl ether, and dibutyl ether; ketone solvents such as acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, and cyclohexanone; fluorine-modified aromatic hydrocarbon solvents such as m-xylene hexafluoride [also known as hexafluorometaxylene] and benzotrifluoride; and fluorine-modified ether solvents such as methyl perfluorobutyl ether. This solvent may be removed after the reaction by known methods such as reduced-pressure distillation, or it may be used as a diluted solution as is, depending on the intended use. The amount of solvent used is not particularly limited, but it is preferable that it be 10 times or less the total mass of the reactants. If too much solvent is used, the reaction rate may decrease significantly.

[0046] Furthermore, polymerization inhibitors may be added during the reaction as needed. There are no particular restrictions on the polymerization inhibitor, but those commonly used as polymerization inhibitors for acrylic compounds can be used. Specifically, examples include hydroquinone, hydroquinone monomethyl ether, 4-tert-butylcatechol, and dibutylhydroxytoluene. The amount of polymerization inhibitor used can be determined based on the reaction conditions, post-reaction purification conditions, and final usage conditions, and is not particularly limited, but is usually 0.01 to 5,000 ppm, and particularly preferably 0.1 to 500 ppm, relative to the total mass of the reaction components.

[0047] Furthermore, during the reaction, an appropriate catalyst may be added to increase the reaction rate. Examples of catalysts include alkyl tin ester compounds such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctoate, dioctyltin diacetate, dioctyltin dilaurate, dioctyltin dioctate, and stannous dioctanoate; titanate esters or titanium chelate compounds such as tetraisopropoxytitanium, tetra-n-butoxytitanium, tetrakis(2-ethylhexoxy)titanium [also known as tetrakis(2-ethylhexyl) orthotitaniumate], dipropoxybis(acetylacetona)titanium, and titanium isopropoxyoctylene glycol; zirconium tetraacetylacetonate, zirconium triputoxymonoacetylacetonate, zirconium monobutoxyacetylacetonate bis(ethylacetoacetate), zirconium dibutoxybis(ethylacetoacetate), zirconium tetraacetylacetonate, zirconium chelate, and bismuth carboxylate compounds. These are not limited to just one type, but can be used as a mixture of two or more types, although the use of titanium compounds or bismuth compounds is particularly preferred in terms of toxicity and reactivity. The reaction rate can be increased by adding these catalysts in an amount of 0.01 to 2% by mass, preferably 0.05 to 1% by mass, relative to the total mass of the reactants.

[0048] The above reaction is carried out at a temperature of 0 to 120°C, preferably 10 to 100°C, for 1 minute to 500 hours, preferably 10 minutes to 48 hours. If the reaction temperature is too low, the reaction rate may be too slow, and if the reaction temperature is too high, polymerization of (meth)acrylic groups may occur as a side reaction.

[0049] After the reaction is complete, the unreacted isocyanate compound and solvent can be removed by distillation, adsorption, filtration, washing, etc., to obtain the fluoropolyether group-containing acrylic compound represented by formula (2) above.

[0050] Furthermore, when stopping the reaction, alcohol compounds such as methanol or ethanol may be added to the system to form urethane bonds with the unreacted isocyanate compound. The resulting urethane (meth)acrylates can be removed in the same way as the unreacted isocyanate compound, but they can also be used as is.

[0051] Another method for introducing a (meth)acrylic group into a fluoropolyether group-containing alcohol compound represented by formula (5) is to react the fluoropolyether group-containing alcohol compound represented by formula (5) with a (meth)acrylic acid halide to form an ester.

[0052] Examples of (meth)acrylate halides include those listed below. [ka] (In the formula, X is a halogen atom such as fluorine, chlorine, or bromine.) Acrylate chloride and methacrylate chloride are particularly preferred.

[0053] It is desirable to charge (meth)acrylic acid halide in an equimolar or greater amount relative to the total amount of hydroxyl groups in the fluoropolyether group-containing alcohol compound to ensure that all hydroxyl groups are reacted. Specifically, it is desirable to use 1 to 6 times the molar amount of (meth)acrylic acid halide, particularly 1.2 to 4 times the molar amount, relative to the amount of hydroxyl groups in the fluoropolyether group-containing alcohol compound in the reaction system. If too little is used, there is a high possibility that some of the fluoropolyether group-containing alcohol compound will remain without the introduction of (meth)acrylic groups.

[0054] In the ester formation reaction in which a fluoropolyether group-containing alcohol compound is reacted with (meth)acrylate halide, it is preferable to use an acid acceptor. The fluoropolyether group-containing alcohol compound represented by formula (5) above, (meth)acrylate halide, and acid acceptor are mixed and stirred. Triethylamine, pyridine, urea, etc., can be used as the acid acceptor. The amount of acid acceptor used should ideally be around 0.9 to 3 times the number of moles of (meth)acrylate halide. Using too little will result in a large amount of untrapped acid remaining, while using too much will make it difficult to remove the excess acid acceptor.

[0055] Furthermore, the reaction may be carried out after dilution with a suitable solvent as needed. Such solvents are not particularly limited as long as they do not react with the hydroxyl group of the fluoropolyether group-containing alcohol compound or the halogen atom of (meth)acrylic acid halide. Specifically, examples include hydrocarbon solvents such as toluene, xylene, and isooctane; ether solvents such as tetrahydrofuran (THF), diisopropyl ether, and dibutyl ether; ketone solvents such as acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, and cyclohexanone; fluorine-modified aromatic hydrocarbon solvents such as m-xylene hexafluoride [also known as hexafluorometaxylene] and benzotrifluoride; and fluorine-modified ether solvents such as methyl perfluorobutyl ether. This solvent may be removed after the reaction by known methods such as reduced-pressure distillation, or it may be used as a diluted solution as is, depending on the intended use. The amount of solvent used is not particularly limited, but it is preferable that it be 10 times or less the total mass of the reactants. If too much solvent is used, the reaction rate may decrease significantly.

[0056] The above reaction is carried out at a temperature of 0 to 120°C, preferably 10 to 100°C, for 1 minute to 500 hours, preferably 10 minutes to 48 hours. If the reaction temperature is too low, the reaction rate may be too slow, and if the reaction temperature is too high, polymerization of (meth)acrylic groups may occur as a side reaction.

[0057] After the reaction is complete, the unreacted (meth)acrylic acid halide and solvent can be removed by distillation, adsorption, filtration, washing, etc., to obtain the fluoropolyether group-containing acrylic compound represented by formula (2) above.

[0058] The refractive index of the fluoropolyether group-containing acrylic compound of the present invention is preferably 1.390 or less, more preferably 1.380 or less, and even more preferably 1.370 or less, at a temperature of 25°C and a wavelength of 589 nm. When such a refractive index is present, a low refractive index cured product useful for optical component applications can be formed. The refractive index can be measured by a refractometer, such as an Abbe refractometer. In the present invention, in order to achieve a refractive index of 1.390 or less under the above conditions, the fluoropolyether group-containing acrylic compound must have a divalent perfluoropolyether group with a number average molecular weight of 500 to 40,000, composed of a perfluoroalkylene group having 1 to 6 carbon atoms and an oxygen atom.

[0059] The fluoropolyether group-containing acrylic compound of the present invention obtained as described above has a perfluoropolyether group as a group having a low refractive index, an amide bond as a group that improves compatibility with photopolymerization initiators, and an acrylic group or an α-substituted acrylic group. Therefore, it has a low refractive index and can form a transparent composition that is compatible with photopolymerization initiators. Furthermore, it can be used as a material for fluorine-containing active energy curable compositions that can be cured by active energy rays such as ultraviolet rays and electron beams. [Examples]

[0060] The present invention will be specifically described below with reference to synthesis examples, comparative synthesis examples, and comparative examples, but the present invention is not limited to the following examples. In the following examples, the number average molecular weight of the perfluoropolyether group is 19 The values ​​shown are calculated from the characteristic peak intensity ratio between the terminal structure and the main chain structure of fluoropolyether group-containing acrylic compounds based on F-NMR analysis.

[0061] [Synthesis Example 1] Synthesis of fluoropolyether group-containing acrylic compound (A-1) Under a dry nitrogen atmosphere, the average structure in the reaction vessel is given by the following formula [ka] (Rf A1 Number average molecular weight: approximately 4,400) Compound (I) represented by the following formula: 100g (0.025 mol), [ka] Compound (i) represented by 12.2 g (0.20 mol) and 100 g of m-xylene hexaflolide were charged and stirred at 60°C for 3 hours under a dry nitrogen atmosphere. IR of the reaction solution confirmed the disappearance of the band originating from the -C(=O)F bond. The resulting reaction solution was washed with water and then distilled under reduced pressure to obtain 92.3 g of fluoropolyether group-containing alcohol compound (II) shown by the following structural formula. [ka] (Rf A1 Number average molecular weight: approximately 4,400)

[0062] Under a dry air atmosphere, 50.0 g of fluoropolyether group-containing alcohol compound (II) obtained by the method described above (0.024 mol of hydroxyl groups) was mixed with 50.0 g of THF and 3.6 g (0.024 mol) of methacryloyloxyethyl isocyanate in a reaction vessel and heated to 50°C. 0.15 g of bismuth carboxylic acid catalyst (XK-640, manufactured by Kusumoto Chemical Co., Ltd.) was added and the mixture was stirred at 50°C for 24 hours. After heating, the mixture was removed by distillation under reduced pressure to obtain a highly viscous liquid. Minoru 46.3g of the substance was obtained. 1 Based on the results of 1H-NMR and IR, it was confirmed that the compound is a fluoropolyether group-containing acrylic compound (A-1) represented by the following formula. [ka] (Rf A1 Number average molecular weight: approximately 4,400)

[0063] [Synthesis Example 2] Synthesis of fluoropolyether group-containing acrylic compound (A-2) Under a dry nitrogen atmosphere, the average structure in the reaction vessel is given by the following formula [ka] (Rf A2 Number average molecular weight: approximately 5,800) Compound (III) represented by the following formula: 100g (0.017 mol), [ka] 8.5 g (0.14 mol) of compound (i) represented by [formula] and 100 g of m-xylene hexafluoride were charged and stirred at 65°C for 8 hours under a dry nitrogen atmosphere. IR of the reaction solution confirmed the disappearance of the band originating from the -C(=O)F bond. After washing the resulting reaction solution with water, it was removed by distillation under reduced pressure to obtain 94.4 g of fluoropolyether group-containing alcohol compound (IV) represented by the following structural formula. [ka] (Rf A2 Number average molecular weight: approximately 5,800)

[0064] Under a dry air atmosphere, in a reaction vessel, 50.0 g of the fluoropolyether group-containing alcohol compound (IV) obtained by the method described above (0.017 mol of hydroxyl groups) was mixed with 50.0 g of m-xylene hexafloride, 3.6 g (0.034 mol) of methacrylate chloride, and 4.4 g (0.043 mol) of triethylamine, and the mixture was stirred at 50°C for 24 hours. After heating, the mixture was washed with water and then distilled under reduced pressure to obtain a highly viscous liquid. Minoru 39.9g of the substance was obtained. 1 Based on the results of 1H-NMR and IR, it was confirmed that the compound is a fluoropolyether group-containing acrylic compound (A-2) represented by the following formula. [ka] (Rf A2 Number average molecular weight: approximately 5,800)

[0065] [Synthesis Example 3] Synthesis of fluoropolyether group-containing acrylic compound (A-3) In a reaction vessel under a dry air atmosphere, 50.0 g of fluoropolyether group-containing alcohol compound (IV) (0.017 mol of hydroxyl groups), obtained in the same manner as in Synthesis Example 2, was mixed with 50.0 g of THF and 2.6 g (0.017 mol) of methacryloyloxyethyl isocyanate, and heated to 50°C. 0.15 g of bismuth carboxylic acid catalyst (XK-640, manufactured by Kusumoto Chemical Co., Ltd.) was added, and the mixture was stirred at 50°C for 24 hours. After heating, the mixture was removed by distillation under reduced pressure, resulting in a highly viscous liquid. Minoru 48.3g of the substance was obtained. 1 Based on the results of 1H-NMR and IR, it was confirmed that the compound is a fluoropolyether group-containing acrylic compound (A-3) represented by the following formula. [ka] (Rf A2 Number average molecular weight: approximately 5,800)

[0066] [Synthesis Example 4] Synthesis of fluoropolyether group-containing acrylic compound (A-4) In a reaction vessel under a dry air atmosphere, 50.0 g of fluoropolyether group-containing alcohol compound (IV) (0.017 mol of hydroxyl groups), obtained in the same manner as in Synthesis Example 2, was mixed with 50.0 g of THF and 4.1 g (0.017 mol) of 1,1-(bisacryloyloxymethyl)ethyl isocyanate, and heated to 50°C. 0.15 g of bismuth carboxylic acid catalyst (XK-640, manufactured by Kusumoto Chemical Co., Ltd.) was added, and the mixture was stirred at 50°C for 24 hours. After heating, the mixture was removed by distillation under reduced pressure, resulting in a highly viscous liquid. Minoru 37.3g of the substance was obtained. 1 Based on the results of 1H-NMR and IR, it was confirmed that the compound is a fluoropolyether group-containing acrylic compound (A-4) represented by the following formula. [ka] (Rf A2 Number average molecular weight: approximately 5,800)

[0067] [Synthesis Example 5] Synthesis of fluoropolyether group-containing acrylic compound (A-5) Under a dry nitrogen atmosphere, the average structure in the reaction vessel is given by the following formula [ka] (Rf A3 Number average molecular weight: approximately 15,300) Compound (V) represented by the following formula: 100g (0.0063 mol), [ka] 3.1 g (0.05 mol) of compound (i) represented by [formula] and 100 g of m-xylene hexafluoride were charged and stirred at 65°C for 8 hours under a dry nitrogen atmosphere. IR of the reaction solution confirmed the disappearance of the band originating from the -C(=O)F bond. After washing the resulting reaction solution with water, it was removed by distillation under reduced pressure to obtain 73.2 g of fluoropolyether group-containing alcohol compound (VI) represented by the following structural formula. [ka] (RfA3 Number average molecular weight: approximately 15,300)

[0068] In a reaction vessel under a dry air atmosphere, 50.0 g of fluoropolyether group-containing alcohol compound (VI) obtained by the method described above (0.0063 mol of hydroxyl groups) was mixed with 50.0 g of THF and 0.98 g of methacryloyloxyethyl isocyanate (0.0063 mol) and heated to 50°C. 0.15 g of bismuth carboxylic acid catalyst (XK-640, manufactured by Kusumoto Chemical Co., Ltd.) was added and the mixture was stirred at 50°C for 24 hours. After heating, the mixture was removed by distillation under reduced pressure to obtain a highly viscous liquid. Minoru 32.8g of the substance was obtained. 1 Based on the results of 1H-NMR and IR, it was confirmed that the compound is a fluoropolyether group-containing acrylic compound (A-5) represented by the following formula. [ka] (Rf A3 Number average molecular weight: approximately 15,300)

[0069] [Synthesis Example 6] Synthesis of fluoropolyether group-containing acrylic compound (A-6) Under a dry nitrogen atmosphere, the average structure in the reaction vessel is given by the following formula [ka] (Rf A2 Number average molecular weight: approximately 5,800) Compound (III) represented by the following formula: 100g (0.017 mol), [ka] Compound (ii) represented by 12.8 g (0.14 mol) and 100 g of m-xylene hexafluoride were charged and stirred at 65°C for 8 hours under a dry nitrogen atmosphere. IR of the reaction solution confirmed the disappearance of the band originating from the -C(=O)F bond. The resulting reaction solution was washed with water and then distilled under reduced pressure to obtain 88.7 g of fluoropolyether group-containing alcohol compound (VII) shown by the following structural formula. [ka] (Rf A2 Number average molecular weight: approximately 5,800)

[0070] Under a dry air atmosphere, 50.0 g of fluoropolyether group-containing alcohol compound (VII) obtained by the method described above (0.033 mol of hydroxyl groups) was mixed with 50.0 g of THF and 5.1 g (0.033 mol) of methacryloyloxyethyl isocyanate in a reaction vessel and heated to 50°C. 0.15 g of bismuth carboxylic acid catalyst (XK-640, manufactured by Kusumoto Chemical Co., Ltd.) was added and the mixture was stirred at 50°C for 24 hours. After heating, the mixture was removed by distillation under reduced pressure to obtain a highly viscous liquid. Minoru 36.6 g of the substance was obtained. 1 Based on the results of 1H-NMR and IR, it was confirmed that the compound is a fluoropolyether group-containing acrylic compound (A-6) represented by the following formula. [ka] (Rf A2 Number average molecular weight: approximately 5,800)

[0071] [Synthesis Comparison Example 1] Synthesis of fluoropolyether group-containing acrylic compound (A-7) Under a dry nitrogen atmosphere, the average structure in the reaction vessel is given by the following formula [ka] (Rf A2 Number average molecular weight: approximately 5,800) Compound (III) represented by the following formula: 100g (0.017 mol), [ka] 6.6 g (0.051 mol) of compound (iii) represented by , 50.0 g of m-xylene hexafloride, and 5.2 g (0.051 mol) of triethylamine were mixed and stirred at 50°C for 24 hours. After heating, the mixture was washed with water and then removed by vacuum distillation to obtain a highly viscous liquid. Minoru 34.4g of the substance was obtained. 1Based on the results of 1H-NMR and IR, it was confirmed that the compound is a fluoropolyether group-containing acrylic compound (A-7) represented by the following formula. [ka] (Rf A2 Number average molecular weight: approximately 5,800)

[0072] Evaluation of the refractive index of compounds The refractive index of the compound was measured using an Abbe refractometer (Atago DR-A1) at a temperature of 25°C and a wavelength of 589 nm. The results are shown in Table 1.

[0073] [Table 1]

[0074] [Examples 1-6, Comparative Example 1] Evaluation of the compatibility of compounds with photopolymerization initiators. The fluoropolyether group-containing acrylic compounds (A-1) to (A-6) obtained in the above Synthesis Examples 1 to 6, or the fluoropolyether group-containing acrylic compound (A-7) obtained in Synthesis Comparative Example 1, were mixed with a photopolymerization initiator (2-hydroxy-2-methylpropiophenone or 2-diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide) in the amounts shown below to obtain a compounded composition. The appearance of the obtained compounded composition was evaluated by visual observation according to the following criteria. The results are shown in Table 2. Formulation A: Contains 100 parts by mass of a fluoropolyether group-containing acrylic compound and 1 part by mass of 2-hydroxy-2-methylpropiophenone. ○ (Good): The appearance of the formulation A is uniform. × (Poor): The appearance of the formulation A is uneven. Formulation B: Contains 100 parts by mass of a fluoropolyether group-containing acrylic compound and 1 part by mass of 2-diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide. ○ (Good): The appearance of the compound composition of formulation B is uniform. × (Poor): The appearance of the compound B is uneven.

[0075] [Table 2]

[0076] The fluoropolyether group-containing acrylic compounds (A-1) to (A-6) of the present invention exhibit a low refractive index, and Examples 1 to 6, using the fluoropolyether group-containing acrylic compounds (A-1) to (A-6) of the present invention, showed excellent compatibility with photopolymerization initiators. On the other hand, the fluoropolyether group-containing acrylic compound (A-7), which does not contain an amide bond in its structure, exhibited a low refractive index, but Comparative Example 1, using the fluoropolyether group-containing acrylic compound (A-7), showed poor compatibility with photopolymerization initiators.

Claims

1. A fluoropolyether group-containing acrylic compound represented by the following general formula (1). V 2 -Rf 2 -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ] 2-a (1) (wherein, Rf 2 is the following formula 【Chemistry 1】 (In the formula, c is an integer between 2 and 6, independent of each unit. d, e, f, g, h, and i are integers between 0 and 200, so that d + e + f + g + h + i = 25 to 200. Each of these units may be linear or branched, and the repeating units shown in the parentheses of d, e, f, g, h, and i may be randomly combined.) This is a divalent perfluoropolyether group represented by , with a number average molecular weight of 4,400 to 40,000. 2 These are independently (b'+1) valent hydrocarbon groups having 1 to 20 carbon atoms. 2 The following structural formulas are independent of each other. 【Chemistry 4】 (In the formula, R 2 (Independently, is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group; W is a single bond, or a divalent or trivalent hydrocarbon group which may contain one or more selected from ether bonds, ester bonds, and urethane bonds; and n is 1 or 2.) A monovalent organic group containing an acrylic group or an α-substituted acrylic group represented by R, and containing, on average, at least one of the acrylic group or α-substituted acrylic group per molecule. 1 This is a hydrogen atom or a monovalent hydrocarbon group having 1 to 8 carbon atoms. 2 is a hydrogen atom, a fluorine atom, or -C(=O)-NR 1 a [Y 2 (X 2 ) b’ ] 2-a This is a monovalent group represented by the formula shown above. a is 0 or 1. b' is an integer from 1 to 10. However, when a = b' = n = 1, W in the above structural formula is a divalent hydrocarbon group containing one or more selected from ether bonds, ester bonds, and urethane bonds.

2. In general formula (1), Rf 2 The following structural formula -CF 2 CF 2 O-(CF 2 CF 2 CF 2 O) q -CF 2 CF 2 - (In the formula, q is an integer between 25 and 200.) 【Chemistry 2】 (In the formula, r is an integer from 1 to 6, C r F 2r O can be linear or branched, s is an integer from 0 to 6, t and u are integers from 1 to 200, t+u is an integer from 25 to 200, and s+t+u is an integer from 25 to 200. v is an integer from 25 to 200. The fluoropolyether group-containing acrylic compound according to claim 1, which is selected from the divalent perfluoropolyether groups represented by .

3. In general formula (1), R 1 The fluoropolyether group-containing acrylic compound according to claim 1, wherein is a hydrogen atom and a is 1.

4. In general formula (1), Y 2 The fluoropolyether group-containing acrylic compound according to claim 1, wherein is represented by any of the following. 【Transformation 3】 (In the formula, * is a bond that connects with N, and ** is X) 2 (This is a bonding hand that connects to [another element].)

5. In general formula (1), X 2 The fluoropolyether group-containing acrylic compound according to claim 1, wherein is represented by any of the following. 【Transformation 5】

6. The fluoropolyether group-containing acrylic compound according to claim 1, wherein the fluoropolyether group-containing acrylic compound represented by formula (1) is represented by any of the following formulas. 【Transformation 6】 (In the formula, X 2 The above is the same. q is an integer from 25 to 200, r is an integer from 1 to 6, and C r F 2r O can be either linear or branched, s is an integer from 0 to 6, t and u are integers from 1 to 200, t+u is an integer from 33 to 200, and s+t+u is an integer from 34 to 200.

7. A fluoropolyether group-containing acrylic compound according to any one of claims 1 to 6, wherein the refractive index at a temperature of 25°C and a wavelength of 589 nm is 1.339 or less.

8. The fluoropolyether group-containing acrylic compound according to any one of claims 1 to 6, wherein 100 parts by mass of the fluoropolyether group-containing acrylic compound and 1 part by mass of 2-hydroxy-2-methylpropiophenone or 2-diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide) are mixed to form a compound composition having a uniform appearance.

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