JP3110814B2 - Siloxane polymer and optical material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a siloxane polymer which can be used as an optical material such as a waveguide for an optical integrated circuit or a plastic optical fiber.

[0002]

2. Description of the Related Art In general, inorganic materials such as quartz glass and multi-component glass are used as base materials for optical components and optical fibers because of their low optical transmission loss and wide transmission band. On the other hand, optical materials based on plastic have also been developed. These plastic optical materials have attracted attention because of their characteristics such as better workability and easier handling than inorganic materials. For example, in an optical fiber, a concentric core in which a plastic having excellent transparency such as polymethyl methacrylate (PMMA) or polystyrene is used as a core and a plastic having a lower refractive index than the core component is used as a sheath (cladding) component. Those having a clad structure are known; However, these plastic optical fibers have the disadvantage that the degree of attenuation of light transmitted inside is greater than that of inorganic fibers. Light is transmitted by totally internally reflecting light incident on one end of an optical circuit or fiber along the length direction. When the light is transmitted inside the plastic, the light is absorbed or scattered. It is important to minimize the factors that increase the attenuation of In optical circuit components, the wavelength of light currently used for optical fiber communication is 650 nm to 1600.
Since light of nm is used, when plastic is used, the reduction of loss in that region is more urgent.

Further, since the mode of propagating light changes depending on the refractive index ratio between the core and the clad, the control of the respective refractive indexes is important for determining the waveguide structure. Conventionally, a plastic optical fiber generally has a multi-mode, so that refractive index control is not considered so much, and a homopolymer having a large refractive index difference is used for a core and a clad. For example, when PMMA is used as the core, the cladding is made of a fluorine-based homopolymer. On the other hand, in a waveguide of an optical circuit component using a single mode, more precise and simple refractive index control is required.

Conventionally, as a method for forming an optical waveguide with plastic, a selective photopolymerization method and a method using a photosensitive resin are known. In the selective photopolymerization method, a patterned optical waveguide is produced by selectively polymerizing or reacting a dopant (acrylic monomer) contained in a polymer with a polymer to change the refractive index. In addition, photosensitive resin,
The method of using a photoresist is to expose a photosensitive resin in a pattern, selectively crosslink, and remove an unexposed portion by development to obtain a core pattern. Both are simpler and easier to manufacture than glass waveguides,
Since each has a large absorption in the near infrared region, it cannot be used for light having a long wavelength of 0.8 μm or more. In addition, in the selective photopolymerization method, the monomer content changes under the volatilization condition of the solvent, the change in the refractive index changes slightly, and there are problems such as the refractive index ratio. In the method using a photosensitive resin, the refractive index varies depending on the amount of irradiation light, and the flexibility of the refractive index ratio is lacking. In addition, there is a problem that the resolution is poor due to swelling during development, and that the surface tends to be uneven. This, together with the problem of the material, also causes high light loss of both.

[0005] Further, in a highly hygroscopic polymer such as polymethyl methacrylate, the vibrational absorption of water OH affects light loss in a high humidity environment. Due to the harmonics of the OH vibration absorption, light transmission loss particularly in the near infrared region is reduced. (For example, Toshikuni Kaino, Polymer, Preprint, Japan (Po
lymer Preprints Japan), 32
Vol. 4, No. 4, 1983, p. 2525), that is, there is a problem that the optical transmission loss fluctuates due to a change in humidity in the use environment conditions.

The glass transition temperature of organic polymers, especially polymethyl methacrylate, is generally around 100 ° C. Therefore, the upper limit of the heat resistance temperature is about 70 ° C., and it cannot be used practically. Optical waveguides and optical fibers using rubber-like polysiloxane have been proposed to solve these problems relating to heat resistance (for example, JP-A-63-98603). However, these require the addition of a cross-linking agent or a post-treatment with radiation to rubberize the liquid polysiloxane, which has a problem in light loss or processability.

On the other hand, an optical waveguide using glass or sapphire as a cladding layer of a waveguide and using ladder-type polysiloxane or polyvinylsiloxane as a core material has been proposed (Japanese Patent Application Laid-Open No. 61-240207). As described above, the mode of propagating light changes depending on the refractive index ratio between the core and the clad, and therefore, the control of each refractive index is important for determining the waveguide structure. However, in the case of this proposal,
Since the clad is limited to a substrate such as glass, there is a problem that usable materials are limited, and there is also a problem that cracking occurs due to a difference in expansion coefficient from the substrate.

[0008]

As described above, at present, low loss over the visible light to near-infrared light regions, easy control of the refractive index, excellent heat resistance, and OH vibration due to moisture absorption are present. There is no plastic optical material that is less affected by absorption. An object of the present invention is to solve these problems and provide an excellent plastic optical material.

[0009]

According to the present invention, as a means for solving these problems, a siloxane-based polymer in which a silicon element of a polysiloxane of chain or ladder type is partially substituted with another element is used. It is characterized by. A siloxane-based polymer having various refractive indices can be obtained by a combination of a silicon element and another substituted element, and the refractive index can be easily controlled. Further, since the main chain structure is siloxane, a low-loss optical material having high moisture resistance can be obtained. Furthermore, the halogen absorption of the side chain greatly reduces the hygroscopicity of the polymer, and the OH vibration absorption intensity based on the hygroscopicity becomes extremely small. The PMMA-based polymer has high hygroscopicity, so the absorption intensity based on OH groups fluctuates greatly due to absorption and dehumidification, and stable light guide characteristics cannot be obtained. The optical material used is characterized in that it can maintain extremely stable optical characteristics. When this plastic optical waveguide is formed on a substrate,
As the substrate, not only a hard substrate such as a silicon substrate and a glass substrate but also a flexible substrate such as a plastic substrate can be used.

Hereinafter, the present invention will be described in detail. The following R
1, R2, R3 and R4 are all CnY2n + 1 (Y is hydrogen, deuterium or halogen, n is a positive integer of 5 or less), a deuterated or halogenated alkyl group, or C6Y5 ( Y is a phenyl group represented by hydrogen, deuterium or halogen), a deuterated or halogenated phenyl group.

First, the first aspect of the present invention is the following general formula (I): And the following general formula (II): (Wherein, M is a tetravalent element excluding Si) and a repeating unit represented by the following formula: Representative examples of tetravalent elements other than Si include Ge, Sn, and Ti.

In the second aspect of the present invention, a repeating unit represented by the above general formula (I) and the following general formula (III): (Wherein M is a trivalent element excluding rare earth elements) is a siloxane-based polymer characterized by having a repeating unit represented by the following formula: Representative examples of trivalent elements other than rare earths include Al, B, P, Bi, and the like.

A third aspect of the present invention is the following general formula (IV): And a repeating unit represented by the following general formula (V): (Wherein M is a tetravalent element excluding Si) and a repeating unit represented by the following formula: Representative examples of tetravalent elements other than Si include Ge, Sn, and Ti. A fourth aspect of the present invention is an optical material using the siloxane-based polymer according to the first, second or third aspect of the present invention.

The general method for producing the polymer of the present invention is as follows. The polymer of the present invention is represented by the following general formulas (VI), (VII) and (VII).
I) (Where M is a tetravalent element, M1 is a trivalent element, R1, R2
Can be obtained by hydrolysis and polymerization of the chloride represented by the above. (VI) (VII) (VIII)
The polymer can also be obtained by polymerization of various alcoholates obtained by reacting a chloride represented by the following formula with an alcohol or condensation polymerization of a chloride and an alcoholate. As a method for this polymerization, as in a general polysiloxane production method, it is usual to dissolve a hydrolyzate such as a chloride or an alcoholate in an organic solvent such as toluene or xylene, and to carry out polymerization with an alkali such as KOH. It is. If n is 6 or more, the glass transition temperature of the polymer is low, and there is a problem in handling.
Is preferably 5 or less. Further, the molecular weight of the polymer is desirably 100,000 or more to avoid cracking when a film is formed.

[0015]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. (Example 1) Contents: 10 g of phenyltrichlorosilane and 1.3 g of aluminum chloride in a flask of about 100 ml.
00 mg KOH was added and mixed with 15 ml toluene. The mixture was refluxed for 16 hours. After completion of the reaction, the mixture was cooled, and a small amount of the precipitate was filtered. Then, the solution was poured into methanol for reprecipitation. It was confirmed by IR analysis and NMR analysis that the obtained polymer was a siloxane-based polymer having a structure of R1 = phenyl group in the general formula (I) and a structure of M = Al in the general formula (III). The molecular weight of the polymer is Mw = 125,000, M
w / Mn = 6.1. The refractive index of this polymer is 1.
The polysilsesquioxane containing no Al increased by 1.6% to 1.56. Further, this polymer exhibited high heat resistance, and no change was observed even after heat treatment at 300 ° C. for 1 hour. Example 2 A deuterated polymer was obtained in the same manner as in Polymer Production Example 1, except that the raw material monomer was deuterated phenyltrichlorosilane d-5. The polymer obtained has a structure of R 1 = deuterated phenyl group in the general formula (I) and the general formula (I
In II), it was confirmed by IR analysis and NMR analysis that the siloxane-based polymer had a structure of M = Al.
The physical properties of the obtained polymer were almost the same as those of the polymer of Example 1. Example 3 Contents 100 g of KOH was added to 10 g of phenyltrichlorosilane and 2.4 g of phenyltrichlorogermanium in a flask of about 100 ml, and 15 ml of
Of toluene. The mixture was refluxed for 16 hours. After completion of the reaction, the mixture was cooled, and a small amount of the precipitate was filtered. Then, the solution was poured into methanol for reprecipitation. The obtained polymer is a siloxane polymer having a structure of R1 = phenyl group in the general formula (I) and a structure of M = Ge and R2 = phenyl group in the general formula (II).
It could be confirmed by R analysis and NMR analysis. The molecular weight of the obtained polymer was Mw = 136000, Mw / Mn = 4.
It was 2. The refractive index of this polymer is 1.58,
1.56 polysilsesquioxane without Ge
However, it rose 1.2%. Further, this polymer exhibited high heat resistance, and no change was observed even after heat treatment at 300 ° C. for 1 hour. (Example 4) Contents of 10 g of phenyltrichlorosilane and 1.3 g of phosphorus chloride in a flask of about 100 ml.
mg KOH was added and mixed with 15 ml toluene. The mixture was refluxed for 18 hours. After completion of the reaction, the mixture was cooled, and a small amount of the precipitate was filtered. Then, the solution was poured into methanol for reprecipitation. It was confirmed by IR analysis and NMR analysis that the obtained polymer was a siloxane polymer having a structure of R1 = phenyl group in the general formula (I) and a structure of M = P in the general formula (III). The molecular weight of the obtained polymer was Mw = 105000, M
w / Mn = 4.5. The refractive index of this polymer is 1.
57, an increase of 0.4%, compared to 1.56 for the phosphorus-free polysilsesquioxane. (Examples 5, 6, 7, 8) Polymers were synthesized in Example 4 using the chlorides shown in Table 1 instead of phosphorus chloride. The polymer obtained in Example 5 is represented by the general formula (I)
= A siloxane-based polymer having a structure of phenyl group and a structure of M = B in the general formula (III), and a polymer obtained in Example 6 has a structure of R1 = phenyl group in the general formula (I). In the formula (III), the polymer is a siloxane-based polymer having a structure of M = Bi, and the polymer obtained in Example 7 has a structure of R1 = phenyl group in the general formula (I) and M = B in the general formula (II). Sn, R2 = a siloxane-based polymer having a phenyl group structure, and the polymer obtained in Example 8 has a structure of R1 = phenyl group in the general formula (I) and M = Ti in the general formula (II); R2 = a siloxane-based polymer having a phenyl group structure, as determined by IR analysis and NMR, respectively.
Analysis confirmed this. Table 1 shows the molecular weight and refractive index of the obtained polymer. (Example 9) Phenyltrichlorosilane d-5 5 g
To 4.5 g of pentyltrichlorosilane d-11 and 1.3 g of aluminum chloride were added 100 mg of KOH,
It was mixed with 15 ml of toluene. The mixture was refluxed for 24 hours. After completion of the reaction, the mixture was cooled, and a small amount of the precipitate was filtered. Then, the solution was poured into methanol for reprecipitation. The obtained polymer is represented by the general formula (I)
IR analysis and NMR analysis confirmed that 1 was a siloxane-based polymer having the structure of a deuterated phenyl group or a deuterated pentyl group and the structure of general formula (III) where M = Al. Molecular weight Mw of the obtained polymer = 910
00, n = 1.53. (Example 10) diphenyldichlorosilane d-10
1 in 15 g and 1.3 g of diphenyldichlorogermanium
00 mg KOH was added and mixed with 15 ml toluene. The mixture was refluxed for 16 hours. After completion of the reaction, the mixture was cooled, and a small amount of the precipitate was filtered. Then, the solution was poured into methanol for reprecipitation. The obtained polymer is a siloxane polymer having a structure of R1 = R2 = deuterated phenyl group in the general formula (IV) and a structure of M = Ge and R3 = R4 = phenyl group in the general formula (V). Is I
It could be confirmed by R analysis and NMR analysis. The molecular weight Mw of the obtained polymer was 106,000, and n was 1.52. (Example 11) 10 g of phenyltriethoxysilane and 1.3 g of aluminum chloride were placed in a flask having a content of about 100 ml.
Was added to 100 mg of KOH and mixed with 15 ml of toluene. The mixture was refluxed for 16 hours. After completion of the reaction, the mixture was cooled, and a small amount of the precipitate was filtered. Then, the solution was poured into methanol for reprecipitation. It was confirmed by IR analysis and NMR analysis that the obtained polymer was a siloxane-based polymer having a structure of R1 = phenyl group in the general formula (I) and a structure of M = Al in the general formula (III). The molecular weight of the obtained polymer was Mw = 1140.
00, Mw / Mn = 6.1. The refractive index of this polymer was 1.60.

[0016]

[Table 1]

Example 12 The polymer obtained in Example 1 was processed into a plate shape, both surfaces were optically polished, and the absorption in the near infrared to visible light region was measured by a spectroscope. As a result, 660, 850, 13
The optical densities (OD) at 00 and 1550 nm are 0.012, 0.008, 0.
010 and 0.020 (cm -1), indicating extremely high translucency. Similarly, absorption was measured for other polymers. Table 2 summarizes the results.

[0018]

[Table 2]

(Example 13) A waveguide was produced using the polymer obtained in Example 1 as a core component and a cladding component. The above two polymers were dissolved in methyl isobutyl ketone to form a solution. First, a clad component polymer was applied to a thickness of about 20 μm on a plastic substrate or a treated silicon substrate. After baking and drying, a core component polymer was applied to a thickness of about 8 μm on the clad component polymer. Next, the core component polymer was processed into a linear rectangular pattern having a length of 50 mm, a width of 8 μm, and a height of 8 μm by photolithography and dry etching. After processing, the clad component was applied on the core component polymer to obtain a waveguide. Wavelength 1300nm, 1500n
m was radiated from one end of the waveguide and the amount of light coming out of the other end was measured to calculate the loss of the waveguide. The loss of this waveguide is 0.5 dB / cm or less, and it can be used for various optical circuits. (Example 14) A waveguide was produced using the polymer obtained in Example 2 as a core component and deuterated polysilsesquioxane d-5 as a cladding component. The above two polymers were dissolved in methyl isobutyl ketone to form a solution. First, a cladding component polymer was applied on a plastic or treated silicon substrate to a thickness of about 20 μm. After baking and drying, a core component polymer was applied to a thickness of about 8 μm on the clad component polymer. Next, a core component polymer is formed by photolithography and dry etching to a length of 50 mm, a width of 8 μm, and a height of
It was processed into a linear rectangular pattern of μm. After processing, the clad component was applied on the core component polymer to obtain a waveguide. Wavelength 130
Light of 0 nm and 1500 nm is irradiated from one end of the waveguide,
The waveguide loss was calculated by measuring the amount of light emerging from the other end. The loss of this waveguide is 0.15 dB / cm
The following is sufficient and can be used for various optical circuits. The optical waveguide was allowed to stand for two days and nights at 60 ° C. and 90% RH, and then taken out, and the light loss was measured. There was no increase in loss due to moisture absorption, and it was confirmed that the moisture resistance was high.

[0020]

As described above, the plastic optical material according to the present invention can control the refractive index in a wide range by changing the content of Si and other elements, and can form a flexible optical substrate on a flexible substrate. Can also be produced. In addition, it has excellent light transmission characteristics in the visible to near-infrared light range, and the loss increase is extremely small even when exposed to high temperature and high humidity conditions. Further, the control of the refractive index is easy, and therefore, it is suitable as a material for an optical integrated circuit in a near-infrared light region. In addition, 650 which has been conventionally used for optical fiber communication is used.
Since it has low loss in the wavelength range of 1600 nm to 1600 nm, it can be combined with multi-component glass and silica-based optical fibers in light / electricity / electricity /
Can be used without light conversion. That is, there is an advantage that an optical signal transmission system such as a local area network which is excellent in economical efficiency can be constituted by optical components manufactured using these optical materials.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-55828 (JP, A) JP-A-61-272238 (JP, A) JP-A-56-159223 (JP, A) 164256 (JP, A) JP-A-4-125929 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 1/04 C08G 77/00 C08G 79/00

Claims (4)

(57) [Claims] 1. The following general formula (I): [Wherein R1 is an alkyl group represented by CnY2n + 1 (Y is hydrogen, deuterium or halogen, n is a positive integer of 5 or less), a deuterated or halogenated alkyl group, or C6Y5 (Y is hydrogen, deuterium, A phenyl group represented by hydrogen or halogen), a deuterated or halogenated phenyl group] and a repeating unit represented by the following general formula (I
I): [Wherein M is any element of Ge, Sn or Ti , R2 is an alkyl group represented by CnY2n + 1 (Y is hydrogen, deuterium or halogen, n is a positive integer of 5 or less), deuterated or halogenated Alkyl group or C6Y5 (Y
Is a siloxane group having a phenyl group represented by hydrogen, deuterium or halogen) and a repeating unit represented by deuterated or halogenated phenyl group].
An optical material characterized by being used . 2. The following general formula (I): [Wherein R1 is an alkyl group represented by CnY2n + 1 (Y is hydrogen, deuterium or halogen, n is a positive integer of 5 or less), a deuterated or halogenated alkyl group, or C6Y5 (Y is hydrogen, deuterium, A phenyl group represented by hydrogen or halogen), a deuterated or halogenated phenyl group] and a compound represented by the following general formula (II)
I): [Wherein M is an element of any of Al, B, P and Bi ] a siloxane-based polymer having a repeating unit represented by
An optical material characterized in that: 3. The following general formula (IV): [Wherein R1 and R2 are the same or different and CnY2n + 1 (Y
Is an alkyl group represented by hydrogen, deuterium or halogen, n is a positive integer of 5 or less), a deuterated or halogenated alkyl group, or a phenyl group represented by C6Y5 (Y is hydrogen, deuterium or halogen); And a repeating unit represented by the following general formula (V): [ Wherein M is any element of Ge, Sn, or Ti , R3,
R4 is the same or different and represents an alkyl group represented by CnY2n + 1 (Y is hydrogen, deuterium or halogen, n is a positive integer of 5 or less), a deuterated or halogenated alkyl group, or C6Y5 (Y is hydrogen, A phenyl group represented by deuterium or halogen) and a repeating unit represented by deuterated or halogenated phenyl group]. 4. An optical material comprising the siloxane-based polymer according to claim 3 .