JPH10316860A - Optical polysiloxane resin containing silica - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optically transparent optical polysiloxane resin containing silica, applicable to an optical element, and having high a light transmittance and hardness. SOLUTION: This optical polysiloxane resin consists essentially of a polysiloxane resin having one or more kinds of substituting groups selected from a group of a 1-4C hydrocarbon group, and a 3-10C fluorohydrocarbon group of the general formula Cn F(2n+1) C2 H4 [(n) is an integer of 1-8] as a substituting groups on the silicon element, and colloidal silica, and the amount of the colloidal silica based on 100 pts.wt. of the polysiloxane resin is <=200 pts.wt. Further, the optical silicone resin has a >=80% spectral transmittance within the wave length range of 250-800 nm, and <=1.43 refractive index.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polysiloxane-based optical resin having a high light transmittance used for an optical element and an optoelectronic element.

[0002]

2. Description of the Related Art In the field of optical elements and optoelectronic elements, attention has been paid to the excellent optical characteristics of polysiloxane-based silicon resins. The rubber elasticity of polydimethylsiloxane is required and used for variable focus optical elements, intraocular lenses, and the like that require flexibility in addition to optical characteristics. Also, studies have been made to use polysiloxane for forming a waveguide. As a material applicable to general optical elements requiring optical characteristics and rigidity with a siloxane resin, an optical material of a moldable polysiloxane composite composed of a polysiloxane resin and fine silica is proposed in JP-A-7-294701. Have been. One of the features of polysiloxane is that the refractive index is lower than that of hydrocarbon resins.

One of the advantages of a low refractive index is that reflection at the interface is suppressed when light passes through the material. It is known that a polymer having a fluorine atom in the molecule has a low refractive index, and the tetrafluoroethylene-hexafluoropropylene copolymer is about 0.1 lower than the ethylene / propylene copolymer. A polysiloxane containing a fluorohydrocarbon group has been proposed for the purpose of improving the water repellency and oil repellency of the polysiloxane resin by bonding the fluorohydrocarbon group to the polysiloxane resin.
-48245, JP-A-6-1848)
These resins do not give any consideration to optical characteristics, and there is a problem in applying them to optical elements.

[0004] A transparent material having a low refractive index is coated on the outermost surface of an optical element, and an antireflection film is provided.
Magnesium fluoride and MgF ₂ have been widely used as a coating material for forming an antireflection film. However, it is necessary to form a film by sputtering on the surface of the optical element, and it is difficult to apply a uniform and wide coating on the surface of the organic equipment technically and apparatus.

[0005] Adding fine silica particles to a polysiloxane resin to improve resin strength is a well known technique, but often results in optically opaque compositions. In particular, in the technique disclosed in JP-A-7-294701, an optically opaque resin can be obtained only when a fluorohydrocarbon group is introduced.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical polysiloxane resin having a high light transmittance and a high surface hardness applicable to an optical element. Another object of the present invention is to provide an optical polysiloxane resin which exhibits excellent light transmittance and has a high surface hardness by using a polysiloxane resin having a substituent group consisting of a hydrocarbon group and / or a fluorohydrocarbon group. To provide.

[0007]

According to the present invention, there is provided a compound having 1 to 4 carbon atoms.
Hydrocarbon group with the general formula _{C n F (2n + 1)} C 2 H 4 - (n is 1 to
A polysiloxane resin having at least one substituent selected from the group consisting of fluorocarbon groups having 3 to 10 carbon atoms represented by the following formula: As an ingredient, the amount of colloidal silica relative to 100 parts by weight of the polysiloxane resin is not more than 200 parts by weight, and 80% in the wavelength range of 250 nm to 800 nm.
An optical silica-containing polysiloxane resin having the above-mentioned spectral transmittance and a refractive index of 1.43 or less.

The polysiloxane resin in the present invention is generally
Formula: RSiO_3/2 It is preferably represented by
Here, R is a hydrocarbon group having 1 to 4 carbon atoms and C_nF
_{(2n + 1)}C _TwoH_FourFluorocarbon having 3 to 10 carbon atoms represented by-
At least one substituent selected from the group consisting of hydrogen and
You.

Examples of the hydrocarbon group include a methyl group,
There are ethyl group, butyl group and propyl group. The fluorohydrocarbon group has a structure in which a perfluorohydrocarbon group is bonded to a silicon atom via an ethylene group. As the perfluorohydrocarbon group, a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoroamyl group, a perfluorohexyl group,
Examples thereof include a perfluorohexyl group and a perfluorooctyl group.

Although colloidal silica contributes to increasing the refractive index when mixed with the polysiloxane resin of the present invention, it cannot be said that colloidal silica is preferable in view of the need for a low refractive index. It is an essential component for developing and maintaining mechanical properties such as surface hardness of the siloxane resin composition.

The colloidal silica that can be used in the present invention has an average particle size of 40 nm or less, preferably in the range of 10 to 40 nm, which is suitable for exhibiting optical transparency. In general, if the particle size is too small, secondary aggregation is likely to occur, and if it is too large, it causes light scattering.

The amount of the colloidal silica used in the present invention is preferably 1 to 200 parts by weight based on 100 parts by weight of the polysiloxane resin. If the amount is less than 1 part by weight, the mechanical strength is insufficient, and if it exceeds 200 parts by weight, the cured polysiloxane resin composition becomes brittle and is not preferable in terms of the refractive index. The amount of colloidal silica is more preferably in the range of 10 to 200 parts by weight, and still more preferably 20 to 100 parts by weight.

The colloidal silica in the present invention includes those usually treated as colloidal silica and those obtained by performing some treatment on colloidal silica, for example, silica gel. It should be noted that it is possible to suppress the formation of the secondary particles of the colloidal silica in the solvent and perform an appropriate treatment on the surface of the colloidal silica in order to uniformly disperse the colloidal silica as long as the production of the polysiloxane resin composition of the present invention is not hindered. .

The transmittance referred to in the present invention is a transmittance which is called a spectral transmittance and is measured by a commercially available visible ultraviolet spectrophotometer. Not something.

It is well known that the refractive index of a polysiloxane resin can be changed by adjusting the type and number of substituents. The type of fluorohydrocarbon group, the type of hydrocarbon group, and the ratio of both types are known. Can vary. In addition to the above, for the curing function as described above, a small amount of an alkenyl group such as vinyl or a SiH group may be included as long as it does not significantly contribute to the refractive index.

The substituent on the silicon of the polysiloxane resin of the present invention tends to have a higher refractive index and a lower surface hardness of the film when the number of carbon atoms of the organic group is increased, and the film tends to be flexible. By the way, in addition to the methyl group, 5% of the fluorohydrocarbon having a chain length n of 8
The polysiloxane contained has a pencil hardness of 5H, but contains 20% of a fluorohydrocarbon group having n of 4 in addition to a methyl group.
In the case of a mixture of a certain degree, the pencil hardness is 5H. Further, nona fluorosilicone hexyl _{(C 4 F 9 C 2 H} 4 -) Taking as an example the case of sodium d-line when replacing the nona fluoroalkyl hexyl 1 mole% of the alkyl substituents on the silicon polysiloxane resin Is 0.0024 lower.

In the present invention, the refractive index indicates the refractive index at the sodium d line of 587.6 nm. The reason that the refractive index of the silica-containing polysiloxane resin for optical use of the present invention is set to 1.43 or less is as follows. The advantage of a low refractive index is that there is less reflection at the air interface. In an optical device using a laser, for example, an optical disc or the like, errors may occur due to a decrease in the amount of input light and output light due to reflection at an interface, and noise may be generated due to formation of an optical interference wave inside the recording phase. Become. The refractive index of the silica-containing polysiloxane resin composition for optical use of the present invention can be lowered to a level of 1.38 or less by the following method. The substituent on the silicon atom of the polysiloxane resin is made only a methyl group, and the amount of colloidal silica added is reduced. The proportion of methyl groups and fluorohydrocarbon groups and the amount of colloidal silica are adjusted.

The polysiloxane resin used in the present invention is described in "Silicone Handbook" edited by Kunio Ito (Nikkan Kogyo Shimbun, 1990), Chapters 12 to 15 or "Latest Silicone Technology" edited by Makoto Kumada and Tadashi Wada ( (CMC, 1986), Chapter 3. In the present invention, an organosilicon compound having a hydrolyzable group and fine silica are mixed in a solvent, and the mixture is subjected to hydrolysis and dehydration polycondensation. In order for the resin of the present invention to be optically transparent, it is preferable to disperse colloidal silica in a solvent and react the organosilicon compound having the hydrolyzable group. When the reaction is performed in this manner, the silanol groups remaining in the colloidal silica react with the hydrolyzed organic silane to form a silica-containing polysiloxane resin in which the colloidal silica is uniformly dispersed in the polysiloxane resin. Incidentally, a catalyst can be added for the purpose of accelerating the hydrolysis. Examples of this catalyst are formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, glutaric acid,
Glycolic acid, tartaric acid and esters thereof can be mentioned.

Generally, in a polysiloxane resin, for example, a hydroxyl group or a hydrolyzable group remains as a substituent bonded to silicon in a molecule. If the amount of the residual hydroxyl group or hydrolyzable group is too large, the storage stability of the polysiloxane resin tends to decrease, and if the amount is too small, the crosslinking does not proceed sufficiently. Therefore, these substituents directly bonded to silicon contained in the polysiloxane resin are preferably 0.1 to 4% by weight. The amount of these substituents can be adjusted to a desired range by a known method, for example, in the case of a hydroxyl group, a method of adding alkoxysilane or the like during or after polysiloxane synthesis. When crosslinking the polysiloxane resin in which the amount of the hydrolyzable group is adjusted as described above, a crosslinking agent may be added for crosslinking. The crosslinking agent that can be used here is 1
Any silicon compound having a siloxane bond having a plurality of hydroxyl groups or hydrolyzable groups in the molecule may be used. Examples of the hydrolyzable group include groups such as methoxy, ethoxy, propoxy, acetoxy, butoxy, and methyl ethyl ketoxime. A catalyst is not necessarily required for crosslinking such a polysiloxane resin, but a catalyst usually used for crosslinking of a polysiloxane may be used, and in consideration of a curing time, a curing temperature, and the like, dibutyltin diacetate, It can be appropriately selected from alkyltin organic acid salts such as dibutyltin dilaurate and dibutyltin octylate, titanates such as butyl titanate, and organic acids such as acetic acid.

As another curing method, when the polysiloxane resin according to the present invention has an alkenyl group, the polysiloxane and a plurality of SiHs in a molecule as a crosslinking agent are used.
Can be mixed with a silicon compound or polysiloxane having the formula (I) and cured using a platinum catalyst used for a hydrosilylation reaction or a curing reaction of an addition type silicone rubber. It should be noted that addition and blending of a known leveling agent such as polyether-modified silicone as an additive may be performed as long as the curing of the present invention is not impaired.

[0021]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. The contents of the aqueous colloidal silica dispersion S and the colloidal silica isopropyl alcohol dispersion T used in the following examples are as follows.

[0022]

[Table 1]

In the following examples, the "colloidal silica aqueous dispersion S" may be referred to simply as "S", and the "colloidal silica isopropyl alcohol dispersion T" may be referred to simply as "T". In the following examples, the refractive index was measured using a polysiloxane solution on a silicon substrate by spin coating to form a thin film, and using ellipsometry (Gardner L115B).

Example 1 32.05 g of colloidal silica isopropyl alcohol dispersion T was placed in a flask,
With stirring, 28.6 ml of water, 25.60 g of methyltriethoxysilane, 3,3,4,4,5,5,6,6,6-
5.87 g of nonafluorohexyltrimethoxysilane,
6.29 g of acetic acid was added. After the addition, the mixed solution
The mixture was heated to 70 ° C. and reacted for 6 hours. Thereafter, the mixture was diluted with 10.65 g of isopropyl alcohol, and 2.4 g (solid content) of dibutyltin dilaurate was gradually added as a curing catalyst. This was spin-coated on a quartz plate at 300 rpm for 10 seconds and further at 30,000 rpm for 60 seconds.
For 2 hours to obtain an optical silica-containing polyorganosiloxane resin thin film. The spectral transmittance of this thin film was measured at 250 to 800 nm using a Hitachi U-3210 spectrophotometer.
The spectral transmittance in the region was measured. In addition, the refractive index was measured by ellipsometry using Gardner (trademark) L115B under the conditions shown in Table 2, the pencil hardness was measured, and the appearance was observed. Table 4 shows the results.

Example 2 32.07 g of an isopropyl alcohol dispersion of colloidal silica T was placed in a flask, and stirred with 5.99 ml of water, 32.13 g of methyltriethoxysilane, n-perfluorooctylethyltriethoxysilane. 83 g and acetic acid 6.29 g were added. After the addition, the mixed solution was heated to 65 to 70 ° C. and reacted for 2 hours. Then, isopropyl alcohol 1.58
g, and 2.4 g (solid content) of dibutyltin dilaurate was gradually added as a curing catalyst. Example 1
Coated on a quartz plate in the same manner as described above, and heated at 120 ° C. for 2 hours to obtain a thin film of silica-containing polyorganosiloxane resin for optical use. The spectral transmittance, refractive index and pencil hardness of this thin film were measured in the same manner as in Example 1, and the appearance was observed. Table 4 shows the results.

(Examples 3 and 4) Coatings of a silica-containing polyorganosiloxane resin were prepared in the same manner as in Example 1 except that the raw materials shown in Table 3 were used, and various measurements and observations were made. Table 4 shows the results.

Examples 5 to 13 Using the raw materials shown in Table 3, the obtained silica-containing polysiloxane was spin-coated on a silicon substrate under the conditions shown in Table 2, dried at 110 ° C., and dried. A resin thin film was formed, and the spectral transmittance, refractive index, and pencil hardness were measured in the same manner as in Example 1, and the appearance was observed. Table 4 shows the results.

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

[0031]

According to the present invention, there is provided an optically silica-containing polysiloxane resin which is optically transparent, has a low refractive index and a high surface hardness. The optical silica-containing polysiloxane resin is applied to the surface of an optical recording medium, and is suitable for exhibiting effects such as antireflection of the surface of the recording medium, prevention of scratching at the time of rubbing, prevention of dirt, and prevention of moisture absorption. . Further, similar effects can be obtained even when applied to an optical element made of an inorganic material or an organic material.

Claims (6)

[Claims] (1) a hydrocarbon group having 1 to 4 carbon atoms and a general formula C _{n
F (2n + 1) C 2} H 4 - (n is an integer of 1 to 8) silicon one or more substituents selected from the group consisting of a fluorohydrocarbon group having 3 to 10 carbon atoms represented by Polysiloxane resin and colloidal silica as a substituent on the atom are the main components,
The amount of colloidal silica based on 100 parts by weight of the polysiloxane resin is 200 parts by weight or less,
An optical silica-containing polysiloxane resin having a spectral transmittance of 80% or more in a wavelength range of 0 nm and a refractive index of 1.43 or less. 2. The optical device according to claim 1, wherein the polysiloxane resin is a condensation polymer of a trifunctional silane, is represented by the following general formula (1), and is a heat-curable polysiloxane resin. Silica containing polysiloxane resin. General formula (1): RSiO _3/2 (R is independently a hydrocarbon group having 1 to 4 carbon atoms and a general formula C _n F
_{(2n + 1)} one or more substituents selected from the group consisting of C ₂ H ₄ — (n is an integer of 1 to 8) and a fluorocarbon group having 3 to 10 carbon atoms. 3. The optical silica-containing polysiloxane resin according to claim 2, wherein R is a methyl group. 4. The silica-containing polysiloxane resin for optical use according to claim 1, wherein colloidal silica is contained in an amount of 20 to 200 parts by weight based on 100 parts by weight of the polysiloxane resin. 5. The polysiloxane resin according to claim 1, wherein R in the general formula (1) is at least one selected from the group consisting of a methyl group and a fluorohydrocarbon group wherein n is in the range of 1 to 6. 5. The silica-containing polysiloxane resin for optical use according to claim 1, wherein the fluorohydrocarbon group is 70% or less of the total R and has a pencil hardness of 6H or more. 6. The colloidal silica is used in an amount of 30 to 100 parts by weight based on 100 parts by weight of the polysiloxane resin in which R in the general formula (1) is a methyl group and a fluorohydrocarbon group in which n is 4. 6. The optical silica-containing polysiloxane resin according to claim 1, wherein the refractive index is 1.38 or less and 1.38 or less, and the pencil hardness is 6H or 6H or more.