Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C33/00—Unsaturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
  • C07C33/02—Acyclic alcohols with carbon-to-carbon double bonds
  • C07C33/025—Acyclic alcohols with carbon-to-carbon double bonds with only one double bond
  • C07C33/035—Alkenediols
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C39/00—Compounds having at least one hydroxy or O-metal group bound to a carbon atom of a six-membered aromatic ring
  • C07C39/02—Compounds having at least one hydroxy or O-metal group bound to a carbon atom of a six-membered aromatic ring monocyclic with no unsaturation outside the aromatic ring
  • C07C39/08—Dihydroxy benzenes; Alkylated derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F3/00—Compounds containing elements of Groups 2 or 12 of the Periodic Table
  • C07F3/003—Compounds containing elements of Groups 2 or 12 of the Periodic Table without C-Metal linkages
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/11—Anti-reflection coatings
  • G02B1/111—Anti-reflection coatings using layers comprising organic materials

Definitions

• the present invention relates to a coating liquid, a method for manufacturing an optical component, and a photographic optical system, in particular, an optical component used as a low refractive index material excellent in an antireflection effect.
• an antireflection film is formed on a surface of an optical component constituting an optical instrument.
• the refractive index ng of a base material is coated at an optical film thickness of ⁇ /4 to light having a wavelength ⁇ , the refractive index theoretically becomes zero.
• a general antireflection film is formed by vacuum depositing a material having the refractive index lower than that of a base material.
• nd is the refractive index to light having a wavelength of 587 nm.
• the refractive index nc is necessary to be
• p represents the porosity.
• a method for preparing a porous film not a dry process such as a vacuum deposition, but a wet process is effective.
• a wet process after a coating material is dissolved or dispersed in a solvent , various coating methods can be used to deposit, and accordingly, there is an advantage that a porous film tends to be readily obtained.
• examples of the methods where magnesium fluoride is prepared according to the wet process include methods illustrated below.
• U.S. Patent No. 4,492,721 and M. Tada et al., J. Mater. Res., Vol. 14, No. 4, Apr, 1999, p. 1610 to 1616 discuss a method where magnesium fluoride is prepared according to a thermal disproportional reaction. After a fluorine-containing magnesium compound or a magnesium fluorocarboxylate compound as a precursor is coated on a substrate, the thermal disproportional reaction is conducted to prepare magnesium fluoride.
• the refractive index is around 1.39, that is, only a value of bulk magnesium fluoride is obtained.
• a deposition temperature thereof reaches 4002 C or 5002 c.
• U.S. Patent No. 5,599,588 discusses a method for obtaining a rare earth and/or alkaline earth halide by at least hydrolyzing a halogenated alkoxide.
• the halogenated alkoxide readily reacts with moisture in air to be instable, the deposition has to be conducted in an inert gas. Accordingly, an optical film has not been stably obtained.
• the present invention is directed to a coating liquid that enables forming a low refractive index magnesium fluoride film from a fluorine-containing organic magnesium compound by a disproportional reaction that uses the heating at a temperature that does not inflict damage on an optical component .
• the present invention is directed to a method for manufacturing an optical component that uses the coating liquid, and to a photographic optical system.
• the present inventors paid attention to a value of the acid dissociation constant (pKa) between magnesium and a fluorine-containing organic material, which constitute a fluorine-containing organic magnesium compound.
• pKa acid dissociation constant
• a weak acidic fluorine-containing organic magnesium compound is instable in air, and accordingly, as it is, it is difficult to stably deposit. Further, when the weak acidic fluorine-containing organic magnesium compound is dissolved in a solvent to form a film according to a wet process , since the weak acidic fluorine-containing organic magnesium compound extremely abhors moisture, an available solvent is largely restricted.
• a coating liquid includes a fluorine-containing organic magnesium compound represented by the following chemical formula ( 1 ) :
• a coating liquid includes a fluorine-containing organic magnesium compound represented by the following chemical formula ( 2 ) :
• Ri represents an alkyl group that may have a substituent group having 2 or more and 4 or less carbon atoms having at least 3 or more fluorine atoms
• R 2 and R 3 respectively, represent an alkyl group that may have a substituent group having 1 or more and 4 or less carbon atoms that may have a fluorine atom, a cycloalkyl group, or an aryl group
• R 4 represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group .
• an optical film is an optical film prepared by coating the coating liquid on a base material to form a film, followed by burning.
• an optical component uses the optical film.
• a coating liquid that enables forming a low refractive index magnesium fluoride film from a
• disproportional reaction at a temperature that does not inflict damage on an optical component , an optical component , and a photographic optical system can be provided.
• an optical component obtained from the coating liquid, and a photographic optical system can be provided.
• Fig. 1 is a diagram illustrating infrared spectra in Example 1 and Comparative Example 1.
• FIG. 2 is a diagram illustrating infrared spectra before and after a disproportional reaction in Example 1.
• Fig. 3A is a diagram illustrating an example of an optical element according to an exemplary embodiment of the present invention.
• Fig. 3B is a diagram illustrating an example of an optical element according to an exemplary embodiment of the present invention.
• FIG. 4 is a diagram illustrating an example of a photographic optical system according to an exemplary embodiment of the present invention.
• a coating liquid according to an exemplary embodiment of the present invention includes a fluorine-containing organic magnesium compound represented by the following chemical formula ( 1 ) :
• a coating liquid according to an exemplary embodiment of the present invention includes a
• Ri represents an alkyl group that may have a substituent group having 2 or more and 4 or less carbon atoms having at least 3 or more fluorine atoms
• R 2 and R 3 respectively, represent an alkyl group that may have a substituent group having 1 or more and 4 or less carbon atoms that may have a fluorine atom, a cycloalkyl group, or an aryl group
• R 4 represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group .
• Rn and Ri can be (CF 3 ) 2 CH or (CF 3 ) 3 C.
• a compound represented by chemical formula (1) or chemical formula (2) according to an exemplary embodiment of the present invention is an asymmetric fluorine-containing organic magnesium compound.
• the asymmetry represents that in chemical formula (1), Rn ⁇ R 2 2 -
• an optical component having an optical film (antireflection film) having an antireflective effect such as excellent low reflection and incident angle characteristics can be manufactured.
• a film made of magnesium fluoride can be readily prepared, not in an inert gas atmosphere, at 200 ⁇ C or less and 1502 C or more.
• a low refractive index can be realized by low temperature burning, so that, an antireflection film having an antireflective effect such as excellent low reflection and incidence angle characteristics, and an optical component therewith can be obtained.
• fluorine-containing precursor is subjected to the
• the bond strength between M-X reflects easiness of the thermal disproportional reaction.
• the disproportional reaction requires larger energy.
• dissociation constant larger than carboxylic acids include phenols, ketones, and diketones .
• magnesium salts with ⁇ -diketones are preferred.
• magnesium fluoride can be stably formed at a low temperature by the disproportional reaction.
• alcohols having at least fluorine can be cited.
• dissociation constant alcohols having at least fluorine
• the reactivity of the disproportional reaction at low temperatures and stability to a moisture-containing atmosphere are considered to be obtained.
• the fluorine-containing precursor for preparing a fluoride can contain a CF 3 group from the viewpoint of the easiness of fluorination by the disproportional reaction.
• Examples of the fluorinated alcohols having a CF 3 group include 2 , 2 , 2- trifluoroethanol (CF 3 CH 2 OH) , 1 , 1 , 1 , 3 , 3 , 3-hexafluoro-2-propanol ( ( CF 3 ) 2 CHOH ) , and
• nonafluorotetrabutyl alcohol (CF 3 ) 3 COH).
• a compound used in the disproportional reaction is (A) an asymmetric fluorine-containing organic magnesium compound (compound 2) illustrated in the right side, and a symmetric fluorine-containing organic magnesium compound (compound 3) is instable in air under the influence of the humidity.
• disproportional reaction is induced generally by heating or by burning. However, an energy line such as UV-ray also can be used. When these are combined, the disproportional reaction can be induced at lower temperatures .
• An optical film according to an exemplary embodiment of the present invention can be prepared by coating a coating liquid containing a asymmetric fluorine-containing organic magnesium compound represented by chemical formula (1) or chemical formula (2) on a base material to form a film, followed by burning.
• the optical film can be constituted of magnesium fluoride .
• a film is formed.
• the methods for forming a coating film include known coating methods such as a dipping method, a spin coat method, a spray method, a printing method, a flow coat method, and a combination thereof.
• a film thickness can be controlled by varying a pulling speed in a dipping method or a substrate rotation speed in a spin coat method, or a concentration of a coating solution.
• a film thickness of a coating film is reduced to about 1/2 to 1/10 by the disproportional reaction. A degree of reduction thereof varies depending on the condition of the disproportional reaction.
• a film thickness of the coating film is preferably controlled so that a film thickness d after the thermal disproportional reaction may be integral multiples of an optical film thickness ⁇ /4 at a design wavelength ⁇ .
• organic solvents examples include alcohols such as methanol , ethanol, propanol, isopropyl alcohol , butanol, ethylene glycol and ethylene glycol-mono-n-propyl ether;
• aliphatic or alicyclic hydrocarbons such as n-hexane, n-octane, cyclohexane, cyclopentane , and
• cyclooctane various kinds of aromatic hydrocarbons such as toluene, xylene, and ethyl benzene; various kinds of esters such as ethyl formate, ethyl acetate, n-butyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether acetate; various kinds of ketones such as acetone, methyl ethyl ketone.
• methyl isobutyl ketone, and cyclohexanone various kinds of ethers such as dimethoxyethane, tetrahydrofuran, dioxane, and diisopropyl ether; various kinds of chlorinated hydrocarbons such as chloroform, methylene chloride, carbon tetrachloride, and tetrachloroethane ; and non-protonic polar solvents such as N-methyl pyrrolidone, dimethyl formamide, dimethyl acetamide, and ethylene carbonate.
• alcohols can be preferably used from the viewpoint of solution stability.
• a reaction temperature is different depending on fluorine-containing organic magnesium compounds used.
• magnesium acetylacetone imparted with hexafluoro-2-propanol by heating at a temperature equal to or more than 200 ⁇ C, the
• disproportional reaction is induced. Further, in the case of magnesium acetylacetone imparted with 2 , 2 , 2-trifluoroethanol , by heating at a temperature equal to or more than 1502 C, the disproportional reaction is induced. At that time, when an atmosphere contains a fluorine compound, fluorination is further promoted to more porosify to result in low refractive index. At that time, the porosification proceeds by heating, and, a heating time is preferably ten minutes to two hours and more preferably 30 minutes to one hour.
• fluorine compound in the coating liquid to increase a fluorine compound in an atmosphere during the disproportional reaction step.
• fluorine compounds added include
• the base material itself can be utilized as a shield.
• the base material in the case of a shape like a concave lens, when the concave lens is disposed with a concave surface directed downward, the same effect can be obtained.
• a functional group for example, -O- or -OH
• fluorine is considered present in a portion other than fluorine. Because of the simultaneous existence of a portion other than fluorine like this, environmental characteristics are considered deteriorated.
• a silicon oxide binder which is excellent in the affinity with a portion other than fluorine and has reactivity therewith is coated onto the resulted fluoride, followed by curing, a low refractive index optical film excellent in the mechanical strength is prepared.
• a silicon oxide precursor various kinds of silicon alkoxides, polysilazanes and polymers thereof can be used. Among these, more reactive polysilazanes are preferred.
• silicon alkoxide the same or different lower alkyl groups such as an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group can be cited.
• polysilazanes examples include polysilazanes that do not substantially contain an organic group
• polysilazanes where an alkyl group, an alkenyl group , an aryl group , a cycloalkyl group , or a group obtained by substituting a part or an entirety of hydrogen atoms bonded to a carbon atom of these groups with a substituent group is bonded to a silicon atom, polysilazanes where a hydrolytic group such as an alkoxy group is bonded to a silicon atom, and polysilazanes where an organic group such as an alkyl group is bonded to a nitrogen atom.
• a curing reaction of the silicon oxide precursor can be promoted by the use of a catalyst.
• a catalyst In the case of silicon alkoxide, an acid or base catalyst can be cited.
• silazane various kinds of amine compounds or metal catalysts and compounds thereof can be used as the catalyst.
• a solution obtained by diluting a silicon oxide precursor with a solvent is coated on the porous magnesium fluoride.
• a hydrophobic solvent examples include petroleum solvents such as xylene or toluene, and dibutyl ether.
• a solution containing a silicon oxide precursor, which is coated on the fluoride contains Si0 2 in terms of Si0 2 in the range of 0.001 ⁇ Si0 2 ⁇ 0.1, preferably in the range of 0.005 ⁇ Si0 2 ⁇ 0.05.
• Si0 2 ⁇ 0.001 an amount of the precursor as the binder is not sufficient, and accordingly, the mechanical strength of the resulted film is not sufficient.
• Si0 2 > 0.1 although the mechanical strength is increased, the refractive index becomes high.
• silica represents a solid content after a solution containing the silicon oxide precursor is completely reacted.
• a solution containing a silicon oxide precursor at 10% by weight in terms of silica is completely reacted, a burned product made of 10% by weight of silica (Si0 2 ) can be obtained.
• Si0 2 a burned product made of 10% by weight of silica
• the silicon oxide precursor is cured by heating.
• silazanes that have the reactivity higher than alkoxides, some of these are converted into silica at room temperature. By wetting and by heating, more dense silica can be formed.
• layers configured to give various kinds of functions thereto can be further disposed.
• an adhesive layer or a primer layer can be disposed to improve the adhesiveness between a transparent base material and a hard coat layer.
• the refractive index of other layer disposed between the transparent base material and the hard coat layer like this is preferably set at an intermediate value of the refractive index of the transparent base material and the refractive index of the hard coat layer.
• the low refractive index optical film like this is used singularly or in a combination with a multilayer film in an optical component, an excellent antireflective property can be realized.
• the optical film is low in the refractive index, when the optical film is used as the upper-most layer in a multilayer configuration, the interfacial reflection can be lowered and oblique incidence characteristics can be improved.
• FIG. 3A An example of an optical component manufactured according to a method for manufacturing an optical component in an exemplary embodiment of the present invention is illustrated in Figs. 3A and 3B.
• Fig. 3A reference numeral
• reference numeral 1 denotes a base material and reference numeral 2 denotes an optical film obtained from a coating liquid according to an exemplary embodiment of the present invention.
• reference numeral 1 denotes a base material
• reference numeral 2 denotes an optical film obtained from a coating liquid according to an exemplary embodiment of the present invention.
• reference numeral 1 denotes a base material
• reference numeral 2 denotes an optical film obtained from a coating liquid according to an exemplary embodiment of the present invention.
• reference numeral 1 denotes a base material
• a multilayer film is formed between the base material and the optical film.
• a single layer film or a multilayer film obtained by alternately laminating a high refractive index layer and a low refractive index layer may be used.
• a film formed between the base material and the optical film for example, inorganic compounds such as titanium oxide (Ti0 2 ) , silicon oxide (Si0 2 ), and magnesium fluoride (MgF 2 ) , a film formed of an organic material such as various resins, organic-inorganic composite film formed by using metal alkoxide as a starting material, or the like can be used.
• an optical film according to the exemplary embodiment of the present invention Since the optical film obtained from a coating liquid according to the exemplary embodiment of the present invention can realize a low refractive index film, an optical film according to the exemplary embodiment of the present invention has an excellent antireflective property. In addition, since the optical film is excellent also in the mechanical strength, even if dust is attached thereto, the dust can be readily wiped, and accordingly, the optical film can be formed on the uppermost surface.
• the optical component according to the exemplary embodiment of the present invention can be applied to various kinds of optical components.
• FIG. 4 illustrates a cross -section of a photographic lens (herein, a telephoto lens is illustrated without particularly restricting thereto.) of such as a camera.
• reference numeral 7 denotes a film that is an imaging surface, or a solid-state image sensor
• FIG. 4 illustrates a photographic optical system where light from an object is focused with the optical members 13, and the object image is imaged on a film or a solid-state image sensor denoted by reference numeral 7. On a surface of each of the optical members 13, an optical film is formed.
• the optical member 13 at least one thereof 13 is the optical member according to the exemplary embodiment, and the optical member 13 focuses light from an object to image an object image on an image sensor.
• At least one of the optical films formed on the optical members 13 has the optical film obtained from a coating liquid according to the exemplary embodiment .
• the optical film obtained from the coating liquid according to the exemplary embodiment is low in the refractive index to have excellent antireflection performance and also excellent mechanical strength, and accordingly, the optical film is preferably formed on the frontmost surface 9.
• the optical film can be used also in binoculars, display devices such as projectors, or window panes.
• a synthetic quartz substrate having a diameter of 30 mm and a thickness of 1 mm was ultrasonic cleansed with isopropyl alcohol and dried, so that a coating substrate was prepared.
• the coating material was spin coated on the quartz substrate at the rotation speed of 2000 RPM. Thereafter, in order not to damage a back surface of the quartz substrate, a hot plate set at 2002 C via an aluminum table having a gap of 1 mm was used to heat to form a film. After the film was formed, a film that cannot be peeled even when touched with a finger was formed.
• Fig. 1 is a diagram illustrating infrared spectra in Example 1 and Comparative Example 1. As the result of measurement, as illustrated in Fig. 1, absorption peaks (indicated with ⁇ in Fig. 1) different from
• Fig. 2 is a diagram illustrating infrared absorption spectra before and after the disproportional reaction in Example 1. As illustrated in Fig. 2, it was confirmed that even when the disproportional reaction was conducted only by heating at 2002 C, after the burning, almost all of the peaks derived from an organic component disappeared, that is, the sample was converted to magnesium fluoride according to the
• a sample was prepared and evaluated in a manner similar to Example 1 except that bis ( 2 , 4-pentanedionate )magnesium (II) was changed to bis(trifluoro-2,4-pentanedionate)magnesium (II) (manufactured by Tokyo Kasei Kogyo Co., Ltd.).
• a sample was prepared and evaluated in a manner similar to Example 1 except that bis( 2 , 4-pentanedionate )magnesium (II) was changed to bis (hexafluoroacetylacetonate)magnesium (manufactured by Tokyo Kasei Kogyo Co., Ltd.).
• Example 2 A sample was prepared and evaluated in a manner similar to Example 1 except that magnesium (Magnesium preparation. manufactured by Aldrich Chemical Co., Inc.) and phenol were allowed to react to prepare a magnesium phenol compound, and the magnesium phenol compound was used in place of
• Example 2 A sample was prepared and evaluated in a manner similar to Example 2 except that the deposition temperature was changed to 1802 c or 1502 C in Example 2.
• Example 2 (II) was dissolved in 25 parts by weight of tetrahydrofuran to prepare a coating material .
• the coating material was deposited on a silicon substrate in a manner similar to Example 1 , followed by measuring an infrared absorption spectrum with a Fourier transform infrared spectrometer (manufactured by Perkin Elmer Inc . ) .
• a coating liquid according to an exemplary embodiment of the present invention can form a low refractive index magnesium fluoride film from a fluorine-containing organic magnesium compound according to a thermal disproportional reaction at a temperature which does not inflict damage on an optical component, and accordingly, the coating liquid can be utilized to prepare an optical film of an optical component.

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