JP3465070B2 - Surface treated paper coated with cyclic olefin resin - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated paper coated with a cyclic olefin resin, and more particularly to a transparent paper obtained by coating a cyclic olefin resin emulsion. The present invention relates to a surface-treated paper excellent in water resistance, surface gloss and scratch resistance, and also excellent in moisture proof and gas barrier properties. [0002] In recent years, surface-treated paper provided with a resin coating layer on paper has been used as a packaging material for foodstuffs and daily necessities.
It is widely used as a liquid food container for milk and juice, and also as a building material such as wallpaper and decorative paper. [0003] As a method for obtaining such a surface-treated paper for packaging, conventionally, various resin emulsions (aqueous dispersions) are applied to the surface of paper and then dried to obtain a paper having a resin-coated surface. Is known how to get. [0004] In the case of obtaining a surface-treated paper having a gas-barrier property as such a surface-treated paper, a vinylidene chloride-based resin such as a vinylidene chloride copolymer has conventionally been used as a resin applied to the paper surface. I have. The surface-treated paper obtained by applying the vinylidene chloride-based resin in this way has excellent gas barrier properties and excellent moisture-proof properties, and is required to have hygroscopic fertilizers, pesticides, salt, sugar, detergents or fragrance retention properties. Food packaging materials such as confectionery,
It is used as building material paper. [0005] However, the surface-treated paper coated with the vinylidene chloride-based resin has a problem that hydrogen chloride is generated at the time of waste incineration and damages the incinerator, and there are also problems in terms of safety to human bodies and pollution. There is also a demand for an alternative to other surface-treated paper. A surface-treated paper obtained by applying a resin emulsion such as a vinyl acetate-based resin or an acrylate-based resin on the surface in place of such a vinylidene chloride-based resin is also known. Properties and gas barrier properties were insufficient. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has excellent transparency, surface gloss and scratch resistance, and also has excellent moisture proof and gas barrier properties. It is another object of the present invention to provide a surface-treated paper coated with a cyclic olefin-based resin that does not generate harmful gas when incinerated for disposal. SUMMARY OF THE INVENTION The surface-treated paper coated with the cyclic olefin resin according to the present invention is represented on the paper surface by the following [A-1].
After the coated cycloolefin resin emulsions,
Cyclic olefins on paper obtained by drying
It is characterized in that a resin coating layer is formed . [A-1] An ethylene / cyclic olefin random copolymer obtained by copolymerizing ethylene and a cyclic olefin represented by the following formula [I ] : (In the formula [I], n is 0 or 1, m
Is 0 or a positive integer; q is 0 or 1;
^{1 to} R ¹⁸ and R ^a and R ^b are each independently a hydrogen atom, a halogen atom or a hydrocarbon group optionally substituted with halogen, and R ^{15 to} R ¹⁸ are bonded to each other to form a monocyclic or polycyclic ring. And the monocyclic or polycyclic ring may have a double bond, and may form an alkylidene group with R ¹⁵ and R ¹⁶ or with R ¹⁷ and R ^18. You may. DETAILED DESCRIPTION OF THE INVENTION [0015] The surface-treated paper coated with the cyclic olefin resin according to the present invention has a specific cyclic olefin resin [ A-1] (hereinafter simply referred to as “cyclic olefin
It may be referred to as a system resin [A]. ) It is obtained by applying an emulsion and drying . Hereinafter, the cyclic olefin resin [A] forming the cyclic olefin resin laminated paper according to the present invention will be described first. Cyclic olefin resin [A] The cyclic olefin resin [A] used in the present invention comprises :
Ru random copolymer Karadadea the [A-1] of ethylene and formula cycloolefin represented by [I]. The softening temperature (TMA) of the cyclic olefin resin [A] used in the present invention as measured by a thermal mechanical analyzer is 0 ° C. or higher, preferably 10 to 2 ° C.
00 ° C, more preferably 10 to 180 ° C, and a glass transition point (Tg) of -10 ° C to 190 ° C, preferably 0 to 1 ° C.
Desirably, the temperature is 70 ° C. The degree of crystallinity of the cyclic olefin resin [A] used in the present invention as measured by X-ray diffraction is 0.
-20%, preferably 0-2%. The intrinsic viscosity [η] of the cyclic olefin resin [A] measured in decalin at 135 ° C. is 0.05 to 10 dl / g.
Preferably 0.3 to 2.0 dl / g, more preferably 0.4.
It is desirably about 1.2 dl / g. First, the cyclic olefin represented by the formula [I ] for forming the cyclic olefin resin [A] used in the present invention will be described. Cyclic olefin embedded image In the above formula [I], n is 0 or 1,
m is 0 or a positive integer, and q is 0 or 1.
When q is 1, R ^a and R ^b are each independently the following atoms or hydrocarbon groups. When q is 0, each bond is bonded to form a 5-membered ring. Form. R ^{1 to} R ¹⁸ and R ^a and R ^b are each independently a hydrogen atom, a halogen atom or a hydrocarbon group. Here, the halogen atom is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. Examples of the hydrocarbon group independently include an alkyl group usually having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 15 carbon atoms, and an aromatic hydrocarbon group. More specifically, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an amyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, and an octadecyl group. A cyclohexyl group is mentioned, and a phenyl group, a naphthyl group, etc. are mentioned as an aromatic hydrocarbon group. These hydrocarbon groups may be substituted with a halogen atom. Further, in the above formula [I], R
^{15 to} R ¹⁸ may be bonded to each other (together with each other) to form a monocyclic or polycyclic ring, and the monocyclic or polycyclic ring thus formed has a double bond. Is also good. The monocyclic or polycyclic rings formed here are specifically exemplified below. Embedded image In the above examples, the carbon atoms numbered 1 or 2 correspond to R in formula [I], respectively.
Represents a carbon atom to which ¹⁵ (R ¹⁶ ) or R ¹⁷ (R ¹⁸ ) is bonded. Further, R ¹⁵ and R ¹⁶ or R ¹⁷ and R ¹⁸ may form an alkylidene group. Such an alkylidene group is usually an alkylidene group having 2 to 20 carbon atoms, and specific examples of such an alkylidene group include an ethylidene group, a propylidene group and an isopropylidene group. The cyclic olefin represented by the above-mentioned formula [I ] is more specifically illustrated below. Embedded image (In the above formula, the numbers 1 to 7 indicate carbon position numbers.) And derivatives obtained by substituting this bicyclo [2.2.1] -2-heptene with a hydrocarbon group. Examples of the hydrocarbon group include 5-methyl, 5,6-dimethyl, 1-methyl, 5-ethyl, 5-n-butyl, 5-isobutyl, 7-methyl, 5-phenyl, 5-methyl-5 -Phenyl, 5-benzyl, 5
-Tolyl, 5- (ethylphenyl), 5- (isopropylphenyl), 5- (biphenyl), 5- (β-naphthyl), 5- (α
-Naphthyl), 5- (anthracenyl), 5,6-diphenyl and the like. Still other derivatives include cyclopentadiene-acenaphthylene adduct, 1,4-methano-1,4,4a, 9a-
Tetrahydrofluorene, 1,4-methano-1,4,4a, 5,10,10a
-Bicyclo [2.2.1] such as hexahydroanthracene
2-heptene derivatives and the like. Tricyclo [4.3.0.1 ^2,5 ] -3-decene, 2-
Tricyclo [4.3.0.1 ^2,5 ] -3-decene derivatives such as methyltricyclo [4.3.0.1 ^2,5 ] -3-decene and 5-methyltricyclo [4.3.0.1 ^2,5 ] -3-decene; Tricyclo [4.4.0.1
^2,5 ] -3-undecene, 10-methyltricyclo [4.4.0.1
^2,5 ] -3-undecene and other tricyclo [4.4.0.1 ^2,5 ] -3
-Undecene derivative. Embedded image (In the above formula, the numbers 1 to 12 indicate the position numbers of carbon.) And derivatives obtained by substituting the same with a hydrocarbon group. Examples of this hydrocarbon group include 8-methyl,
8-ethyl, 8-propyl, 8-butyl, 8-isobutyl, 8-
Hexyl, 8-cyclohexyl, 8-stearyl, 5,10-dimethyl, 2,10-dimethyl, 8,9-dimethyl, 8-ethyl-9-methyl, 11,12-dimethyl, 2,7,9-trimethyl, 2,7-dimethyl-9-ethyl, 9-isobutyl-2,7-dimethyl, 9,11,12-trimethyl, 9-ethyl-11,12-dimethyl, 9-isobutyl-1
1,12-dimethyl, 5,8,9,10-tetramethyl, 8-ethylidene, 8-ethylidene-9-methyl, 8-ethylidene-9-ethyl,
8-ethylidene-9-isopropyl, 8-ethylidene-9-butyl, 8-n-propylidene, 8-n-propylidene-9-methyl, 8
-n-propylidene-9-ethyl, 8-n-propylidene-9-isopropyl, 8-n-propylidene-9-butyl, 8-isopropylidene, 8-isopropylidene-9-methyl, 8-isopropylidene-9- Ethyl, 8-isopropylidene-9-isopropyl, 8-isopropylidene-9-butyl, 8-chloro, 8-bromo, 8-fluoro, 8,9-dichloro, 8-phenyl, 8-methyl
-8-phenyl, 8-benzyl, 8-tolyl, 8- (ethylphenyl), 8- (isopropylphenyl), 8,9-diphenyl, 8- (biphenyl), 8- (β-naphthyl), 8- ( α-naphthyl), 8- (anthracenyl), 5,6-diphenyl and the like. Still other derivatives include adducts of (cyclopentadiene-acenaphthylene adduct) with cyclopentadiene. Pentacyclo [6.5.1.1
^3,6 .0 ^2,7 .0 ^9,13] -4-pentadecene, and derivatives thereof. [0042] pentacyclo [7.4.0.1 ^2,5 .1 ^9,12 .0 ^8,13]
-3-pentadecene, and derivatives thereof. Pentacyclo ^{[6.5.1.1 3,6 .0 2,7 .0 9,13]} -4,10- penta octadecadienoic Penta cyclopentadiene octadecadienoic compound such. [0043] pentacyclo [8.4.0.1 ^2,5 .1 ^9,12 .0 ^8,13]
-3-hexadecene and its derivatives. Pentacyclo ^{[6.6.1.1 3,6 .0 2,7 .0 9,14]} -4- hexadecene, and derivatives thereof. [0044] hexacyclo [6.6.1.1 ^3,6 .1 ^10,13 .0 ^2,7 .0
^9,14] -4-heptadecene and derivatives thereof. Heptacyclo ^{[8.7.0.1 2,9 .1 4,7 .1 11,17 .0} 3,8 .0 12,16] -5- eicosene, and derivatives thereof. [0045] heptacyclo [8.8.0.1 ^2,9 .1 ^4,7 .1 ^11,18 .0
^3,8 .0 ^12,17] -5-heneicosene, and a derivative thereof.
Octacyclo ^{[8.8.0.1 2,9 .1 4,7 .1 11,18 .1} 13,16 .0 3,8 .0
^12,17 ] -5-docosene and derivatives thereof. [0046] Nonashikuro [10.9.1.1 ^4,7 .1 ^13,20 .1 ^15,18.
0 ^2,10 .0 ^3,8 .0 ^12,21 .0 ^14,19] -5-pentacosene and derivatives thereof. Nonashikuro [10.10.1.1 ^5,8 .1 ^14,21.
1 ^{16, 19} .0 ^2,11 .0 ^4,9 .0 ^{13, 22} .0 ^{15, 20]} -6-hexacosenoic,
And its derivatives. Although specific examples of the cyclic olefin represented by the general formula [I ] are shown above, more specific structural examples of these compounds are described in Japanese Patent Application No. 5-1961 of the present applicant.
No. 475, paragraphs [0032] to [005] of the original specification.
The structural example of the cyclic olefin shown in 4] can be used. The cyclic olefin represented by the above general formula [I ] can be produced by subjecting cyclopentadiene and an olefin having a corresponding structure to a Diels-Alder reaction. These cyclic olefins can be used alone or in combination of two or more. The cyclic olefin-based resin used in the present invention is obtained by using the cyclic olefin represented by the above formula [I ] , for example, JP-A-60-168708, JP-A-61-120816, JP-A-61-115912, Id 6
1-115916, 61-271308, 61-272216, 62-252
It can be produced by appropriately selecting conditions according to the method proposed by the present applicant in Japanese Patent Publication Nos. 406 and 62-252407. [A-1] The ethylene / cyclic olefin random copolymer is a copolymer derived from a cyclic olefin in an amount of usually 30 to 90 mol%, preferably 40 to 85 mol%, of a structural unit derived from ethylene. Unit is usually 1
It is contained in an amount of 0 to 70 mol%, preferably 15 to 60 mol%. The ethylene composition and the cyclic olefin composition are measured by ¹³ C-NMR. This [A-1]
In the ethylene / cyclic olefin random copolymer, the structural units derived from ethylene and the structural units derived from the cyclic olefin are randomly arranged and bonded, and have a substantially linear structure. ing. The fact that the copolymer is substantially linear and does not have a substantially gel-like cross-linked structure means that when the copolymer is dissolved in an organic solvent, the solution contains an insoluble component. You can confirm by not having. For example, when the intrinsic viscosity [η] is measured, it can be confirmed by completely dissolving this copolymer in decalin at 135 ° C. In the [A-1] ethylene / cyclic olefin random copolymer used in the present invention, the above-mentioned formula [I ]
It is considered that at least a part of the cyclic olefin represented by the formula (III ) constitutes a repeating unit represented by the following formula [III ] . Embedded image In the formula [III], n, m, q, R ¹ to
R ¹⁸ and R ^a and R ^b have the same meanings as in formula [I]. The [A-1] ethylene / cyclic olefin random copolymer used in the present invention is derived from other copolymerizable monomers as necessary within a range not to impair the object of the present invention. May be included. Examples of such other monomers include olefins other than the above-described ethylene or cyclic olefin, and specific examples thereof include propylene, 1-butene, 1-pentene, 1-hexene, and 3-olefin. Methyl-1-butene, 3-
Methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1
-Pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene , 1-decene, 1-
Α- having 3 to 20 carbon atoms such as dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene
Olefin, cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene and cyclooctene, 3a, 5,6,7a-tetrahydro-4,7-methano Cycloolefins such as -1H-indene, 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene, dicyclopentadiene and 5-vinyl-2 Non-conjugated dienes such as -norbornene. These other monomers can be used alone or in combination. [A-1] Ethylene
In the cyclic olefin random copolymer, structural units derived from other monomers as described above usually have 20 units.
It may be contained in an amount of up to 10 mol%, preferably up to 10 mol%. The [A-1] ethylene / cyclic olefin random copolymer used in the present invention comprises ethylene and the formula [I ]
In a cycloolefin represented it can be manufactured by the manufacturing method disclosed in the above publication using. Among these, this copolymerization is carried out in a hydrocarbon solvent, and using a catalyst formed from a vanadium compound and an organoaluminum compound soluble in the hydrocarbon solvent as the catalyst, [A-1] ethylene / cyclic olefin random copolymer is used. It is preferred to produce a polymer. In this copolymerization reaction, a solid group IVB metallocene catalyst can also be used. Where solid IV
The group B metallocene-based catalyst is a catalyst comprising a transition metal compound containing a ligand having a cyclopentadienyl skeleton, an organic aluminum oxy compound, and an organic aluminum compound optionally added. Here, the group VI transition metal is zirconium, titanium or hafnium, and these transition metals have at least one ligand having a cyclopentadienyl skeleton. here,
Examples of the ligand having a cyclopentadienyl skeleton include a cyclopentadienyl group or an indenyl group, a tetrahydroindenyl group and a fluorenyl group which may be substituted by an alkyl group. These groups may be bonded via another group such as an alkylene group. Further, ligands other than the ligand having a cyclopentadienyl skeleton include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group and the like. Further, as the organic aluminum oxy compound and the organic aluminum compound, those usually used for producing an olefin resin can be used. Such a solid group IVB metallocene catalyst is described in, for example, JP-A-61-221206, JP-A-64-106, and JP-A-2-173112. ## EQU00001 ## [0076] The following is an explanation of the operation. Preparation of Emulsion The emulsion (aqueous dispersion) of the above-mentioned cyclic olefin resin [A] can be prepared by the following emulsion preparation method. For example, a drum emulsification method in which a resin, water and an emulsifier are added together and emulsification is performed, a pulverization method in which a pre-ground resin is dispersed in water together with an emulsifier, a resin dissolved in an organic solvent, an emulsifier and water are mixed, and then the organic solvent is mixed. , A homomixer method in which emulsification is performed using a homomixer, a phase inversion method, and the like, which can be appropriately selected depending on the type of the cyclic olefin resin [A]. In the present invention, the emulsion (aqueous dispersion) thus prepared contains the cyclic olefin resin [A] in an amount of 10 to 60% by weight (solid content). It is desirable. In preparing the cyclic olefin resin [A] emulsion, it is preferable to use an emulsifier. As the emulsifier, a surfactant can be used. For example, a nonionic surfactant, an anionic surfactant, or the like can be used. Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene sorbitan ester, and polyoxyethylene alkylamine ether. Examples of the anionic surfactant include fatty acid salts, higher alcohol sulfates, sodium alkylbenzenesulfonate, naphthalenesulfonic acid formalin condensate, and polyoxyethylene alkyl ether sulfate. Of these, sodium alkylbenzene sulfonate, polyoxyethylene alkyl ether sulfate and the like are preferably used. These are 2
A combination of more than one species can be used. The above emulsifier (surfactant) is used in an amount of 0.05 to 10% by weight, preferably 0.1% by weight, based on the resin [A].
Preferably, it is used in an amount of up to 7% by weight. In preparing the cyclic olefin resin [A] emulsion, a thickener, a basic substance, an antifoaming agent, and the like can be used as necessary. Examples of the thickener include alginate such as ammonium alginate, potassium alginate and sodium alginate, mineral thickeners such as bentonite clay, sodium polyacrylate, ammonium polyacrylate, acrylic emulsion copolymer, crosslinked acrylic emulsion Acrylic acid-based thickeners such as copolymers, carboxymethylcellulose, methylcellulose,
And fibrous derivatives such as hydroxypropylmethylcellulose and hydroxyethylcellulose. Of these, carboxymethyl cellulose and the like are preferably used. Examples of the antifoaming agent include vegetable oils such as castor oil, soybean oil and linseed oil, mineral oils such as spindle oil and liquid paraffin, fatty acids such as stearic acid and oleic acid, oleyl alcohol, polyoxyalkylene glycol and octyl oil. Alcohols such as alcohol, ethylene glycol distearate, fatty acid esters such as polyoxyethylene sorbitan monolaurate, tributyl phosphate, phosphate esters such as sodium octyl phosphate, amides such as polyoxyalkylene amide, aluminum stearate, Metal soaps such as potassium oleate and calcium stearate; silicons such as dimethyl silicon and polyether-modified silicon; and amines such as diamylamine and polyoxypropylene alkylamine. Kind and the like. The cyclic olefin resin [A] emulsion used in the present invention may contain an adhesive and other additives in addition to the above, if necessary. Surface-treated paper In the present invention, the cyclic olefin-based resin [A] emulsion prepared as described above is then applied to paper and dried to obtain a surface-treated paper coated with the cyclic olefin-based resin. As the paper, conventionally known papers such as kraft paper, tissue paper, hybrid paper, paperboard and synthetic paper are widely used without any particular limitation. In order to coat the cyclic olefin resin [A] emulsion on paper, a known coating method such as coating with a coater, brush coating, or spraying with a spray gun can be appropriately used. In the present invention, since the resin coating layer is formed on the paper by using the emulsion, the resin coating layer can be easily formed not only on a sheet of paper but also on papers of various shapes. The paper thus coated with the cyclic olefin resin [A] emulsion is then dried naturally or forcibly by heating, and can be dried usually at 60 to 200 ° C., preferably 80 to 180 ° C. . In the surface-treated paper coated with the cyclic olefin resin obtained as described above, the thickness of the cyclic olefin resin [A] layer can be appropriately selected according to the intended use. 1 mm, preferably 50
It is desirable that it is from μm to 0.5 mm. The surface-treated paper coated with the cyclic olefin resin according to the present invention may be provided with another coating layer if necessary. The surface-treated paper coated with the cyclic olefin resin according to the present invention is excellent in transparency, surface gloss and scratch resistance, and also excellent in moisture proof and gas barrier properties. The surface-treated paper is excellent in tearability and can be easily opened in any direction. Further, the surface-treated paper coated with the cyclic olefin-based resin does not generate harmful gas during waste incineration. The surface-treated paper coated with the cyclic olefin resin according to the present invention can be suitably used for a wide range of uses such as various packaging materials, containers and building materials.
For example, medicine, food, dairy products, alcoholic beverages, daily necessities, miscellaneous foods, daily necessities, etc. as packaging materials, milk, juice liquid foods, furniture, flooring,
It can be used as building materials such as ceiling, wallpaper, decorative paper, etc. EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. Example 1 [Preparation of emulsion] MFR (260 ° C., 2.16 kg)
Is 30 g / 10 min, and the intrinsic viscosity [η] (1
0.65 dl / g in 35 ° C. decalin) and TMA
(Measured by thermal mechanical analyzer) is 90 ° C. Ethylene and tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3-
One liter of toluene was added to and dissolved in 125 g of a random copolymer with dodecene (hereinafter referred to as ETCD-3). The obtained ETCD-3 / toluene solution 5
500 g of distilled water and 1.44 g of sodium dodecylbenzenesulfonate were added to 00 g, and the mixture was stirred and mixed at 10,000 rpm for 15 minutes using a homomixer. Then, 0.72 g of carboxymethylcellulose was added and the mixture was further stirred. Next, the stirred liquid was distilled under reduced pressure by an evaporator to remove toluene and a part of water, thereby obtaining an emulsion (aqueous dispersion) having an ETCD-3 polymer concentration of 30% by weight. [Coating on Kraft Paper] The emulsion obtained as described above was coated on a kraft paper having a thickness of 100 μm with a coater to a thickness of 100 μm, and dried at 100 ° C. Next, the surface was smoothed with a metallic heat roll set at 120 ° C. Table 1 shows the moisture resistance of the surface-treated kraft paper thus obtained. Note that the moisture resistance is determined by the moisture permeability coefficient (A
(STM F1249, 40 ° C., RH 90%). Comparative Example 1 In Example 1, a methacrylic acid / styrene copolymer (methacrylic acid content 2
0 wt%) to obtain a surface-treated kraft paper in the same manner as in Example 1. Table 1 shows the moisture resistance of the surface-treated kraft paper. [Table 1]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-93899 (JP, A) JP-A-51-7508 (JP, A) JP-A-5-339897 (JP, A) JP-A-2- 196832 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 19/00-27/42

Claims (1)

(57) [Claims] [Claim 1] A cyclic olefin resin emulsion represented by the following [A-1] is applied to the surface of paper, and then dried. Surface-treated paper having a resin coating layer formed thereon; [A-1] an ethylene / cyclic olefin random copolymer obtained by copolymerizing ethylene with a cyclic olefin represented by the following formula [I]; (In the formula [I], n is 0 or 1, m is 0 or a positive integer, q is 0 or 1, R ^{1 to} R ¹⁸ and R ^a and R ^b are each independently hydrogen. An atom, a halogen atom or a hydrocarbon group optionally substituted by halogen, wherein R ^{15 to} R ¹⁸ may be bonded to each other to form a monocyclic or polycyclic ring; It may have a double bond, and R ¹⁵ and R ¹⁶ or R ¹⁷ and R ¹⁸ may form an alkylidene group.)