JPH0680441B2 - Polymer Monomer for Waveguide Core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deuterated methacrylate monomer having a lower fluoroalkyl group in the ester side chain, which is useful as a monomer for a polymer for a waveguide core.

In recent years, an optical communication system using pulsed light has attracted attention as a means of transmitting information or communication, and various optical materials are being developed as parts and materials for constructing the optical communication system. Most of the optical materials are inorganic materials such as quartz, but plastic materials also have workability, flexibility,
Since it has features such as handleability, it has been partially put into practical use as an information transmission means. Optical materials with a waveguiding structure are classified into a clad type and a light focusing type. Both of them consist of a core layer at the center and a clad layer surrounding it. In the clad type, the refractive index of the core part is Is higher than the refractive index of the cladding.

The light is transmitted while being totally reflected at the core-clad interface, but the light transmitted through the waveguide is attenuated by the absorption of C—H groups of the organic polymer forming the core.

So far, polystyrene and polymethylmethacrylate, which have relatively good transparency, have been studied as organic polymers for cores.

Polymethylmethacrylate is well known as an organic glass and is easy to purify optically and chemically.
Most excellent light guiding property. However, the optical communication systems currently under study use light with a wavelength in the near-infrared light region of 0.85 μm or 1.3 μm, so normally light in the visible light region passes through well, but near infrared light transmission It was practically difficult to use polymethylmethacrylate, which is inferior to the above, as an organic polymer for a core of an optical material for an optical communication system. When polymethylmethacrylate is used for near-infrared light, the most problematic problem is C—H absorption. Therefore, it has been attempted to deuterate hydrogen to shift the low loss band to the long wavelength side. I am. By polymerizing such MMA-d ₈ (perdeuteromethylmethacrylate), it is possible to obtain an optical material with a small loss even in the near infrared region.
It is reported in No. 65556 (Japanese Patent Publication No. 57-51645). However, since deuterated methanol used as the raw material of the MMA-d ₈ are difficult to obtain, a large amount of optical materials using MMA-d ₈ as a monomer of the core for organic polymers, and, for stable supply is difficult. That is, deuterated methanol is produced by a special reaction called high pressure contact reaction between carbon monoxide and deuterium gas. In addition, deuterium gas as a raw material is an extremely valuable substance obtained by electrolysis of rare deuterated water. Therefore, it cannot be done easily. In view of this situation,
JP-A-58-154803 describes an ester of deuterated methacrylic acid with ordinary non-deuterated methanol.
It is disclosed that MMA-d ₅ can also be used as an organic polymer for the core. But methyl methacrylate is
The water absorption of the polymer is relatively high, and in this respect MMA-d ₈
And the same can MMA-d _5, there can interfere with loss reduction effect by much trouble introduced deuterated.

On the other hand, by introducing fluorine into the organic polymer,
It is known that the water absorption of polymers is significantly reduced. However, in this case, the refractive index almost always decreases, and the higher the fluorine content, the greater the degree of this decrease. Therefore, when such a fluorine-introduced organic polymer is used as the core of the waveguide, what can be used as the cladding is limited in terms of the refractive index, and therefore it is necessary to minimize the introduction of such fluorine. is there. As an expedient for such purposes, a methyl group of the ester side chain is the synthesis of trifluoromethyl methacrylate -d ₅ which is fluorinated. However, in this case, fluorine and from unique property synthesis on having the fluorine compound It is difficult to obtain the starting material trifluoromethylmethacrylate, and it is very difficult to handle it. Therefore, the above-mentioned problems in supply cannot be solved.

In view of such a situation, the present inventors have no fear of interfering with the effect of reducing the loss due to deuteration, and are trifluoromethyl which is a monomer for optical materials with a small degree of decrease in the refractive index and which is easy to synthesize. As a result of earnest studies on a compound similar to methacrylate-d ₅ , the present invention has been accomplished by discovering the lower fluoroalkyl deuterated methyl methacrylate monomer of the present invention.

That is, the present invention has the general formula [I] (In the formula, R ¹ and R ² represent a lower fluoroalkyl group or hydrogen, provided that at least one of R ¹ and R ² represents a lower fluoroalkyl group.) It is the invention of the monomer.

In other words, the present invention is deuterated methacrylic acid that can be used as a raw material for a core polymer of an optical material for optical communication, and a hydrogen atom on the 1-position carbon atom and a hydrogen atom on the other carbon atom. Is an invention of a fluoroalkyl deuterated methacrylate monomer, which is an ester of a non-deuterated alcohol having 2 or more carbon atoms in which the hydrogen atom is replaced by a fluorine atom.

In the fluoroalkyl deuterated methacrylate monomer of the present invention represented by the general formula [I], In examples of the group represented, for _{example, -CH 2 CF 3, -CH 2} CF 2 C
Lower fluoroalkyl groups such as HF ₂ , —CH ₂ CF ₂ CF ₃ , —CH (CF ₃ ) _{2 and the} like can be mentioned.

The introduction of these fluoroalkyl groups significantly reduces the water absorption of the polymer. On the other hand, since the C—H group is also introduced, the absorption loss resulting from this is brought about, but the introduction of the fluoroalkyl group makes the obtained polymer bulky, and the C—H group per unit volume is The content is extremely low in the case of any fluoroalkyl group. As a result, the effect of suppressing the occurrence of loss due to water absorption of the polymer exceeds the increase in loss value due to the inclusion of C—H groups, and a light guide material having a remarkably small absorption loss in the near infrared light region is obtained. be able to.

Further, fluoroalkyl deuterated methacrylate monomers of the present invention, a reduction in the refractive index due to introduction of fluorine is extremely small, it methyl methacrylate (▲ n ²⁰ _D ▼ = 1.414
It is only about 0.05 lower than 0). Therefore, the polymer obtained from the monomer of the present invention can be sufficiently used as the core of the waveguide.

Fluoroalkylmethacrylate monomers have been used as optical materials until now, but all of them have been used only as raw materials for polymers for clad, and they are going to be used as raw materials for organic polymers for core. Thoughts have never existed before.

The fluoroalkyl deuterated methacrylate monomer of the present invention can be synthesized according to a conventional method for producing a fluoroalkyl methacrylate, for example, CD ₃ COCD ₃
A cyanohydrin compound can be obtained by the reaction of adding HCN, and can be easily synthesized from the cyanohydrin compound through the process represented by the following formula.

Or However, R is -CH ₂ CF ₃ , -CH ₂ CF ₂ CHF ₂ , -CH ₂ CF ₂ CF ₃ , -CH
It represents a lower fluoroalkyl group such as (CF ₃ ) ₂ .

Here, the fluoroalcohol represented by R-OH is a compound that can be obtained very easily as compared with deuterated methanol and trifluoromethanol which have been conventionally used as a raw material of a monomer for a core polymer. For example, it is widely used as a solvent for analysis.

INDUSTRIAL APPLICABILITY The present invention contains fluorine at the same time even though it has a C—H group in the ester side chain, and as a result, has a significantly small light guiding loss and can be stably supplied in a large amount in a unit amount for an optical material. It provides the body and contributes greatly to the industry.

Examples will be shown below.

Example 1. Synthesis of acetone -d ₆ of 2,2,2-trifluoroethyl methacrylate -d ₅ 500g (7.8mol), was added KCN1g, thereto, at 15 to 20 ° C., the HCN316g (11.7mol) After the dropping, the reaction is allowed to proceed at 15-18 ° C for 30 minutes after the dropping. After the reaction was completed, concentrated sulfuric acid was added to adjust the pH to 1, HCN was driven out by N ₂ bubbling, and acetone cyanohydrin-d ₆ 717 g was obtained. Yield about 100%.

Acetone cyanohydrin-d ₆ 71 thus obtained
15g of concentrated sulfuric acid (15.6mo) prepared in advance with 7g (7.08mol)
l) into the solution at 70-80 ℃, and 125-130 ℃ after the completion of the addition.
After 30 minutes at room temperature, cool to 40 ℃, inject 1130 g of water,
React at 0-85% for 2 hours. After completion of the reaction, distill,
After distilling, 1150 g is obtained. The distillate was extracted with CH ₂ Cl ₂ 400 ml × 2, dehydrated with MgSO ₄ 100 g, dried, and then MgSO ₄ was filtered off.
₂ Cl ₂ was distilled off under reduced pressure to obtain 493 g of methacrylic acid-d ₅ . Yield 69.4%.

Methacrylic acid-d ₅ 493 g (5.4 mo
l), 248g (1.8mol) of PCl _{3 was} added dropwise at 60-65 ℃,
Incubate at ~ 70 ° C for 1 hour. After completion of the reaction, leave it still, H ₃ PO ₃
Is removed by decanting to obtain 533 g of methacrylic acid chloride-d ₅ . Yield 90%. bp44 ℃ / 120-130mmHg.

Thus obtained methacrylic acid chloride-d ₅ 280 g
(2.56mol), trifluoroethanol 266g (2.66mo
l) was added and the mixture was refluxed at 93 ° C. for 3 hours, and 396 g of the distillate obtained by distillation was washed with 370 ml of 10% NaHCO ₃ aqueous solution, washed with water, dried over MgSO ₄ , and dried for 2,2,2. - obtaining trifluoroethyl methacrylate -d ₅ 322.5. Yield 70%. bp48-49.5 ° C
/ 85mmHg. Refractive index: ▲ n ²⁰ _D ▼ = 1.3612. IR (neat): 174
0 cm ^-1 Example 2. 2,2,3,3-tetrafluoro-1-propyl methacrylate Synthesis Example of -d ₅ 1. of methacrylic acid chloride was synthesized in the same manner -
to d ₅ 80g (0.73mol), 2,2,3,3- tetrafluoro-1
After adding 100 g (0.76 mol) of propanol and reacting at 95 ° C for 5 hours, 153 g of the distillate obtained by distillation was washed with 100 ml of 10% NaHCO ₃ aqueous solution, washed with water, dried with 10 g of molecular sieves 4A, and 139 g of 2,2,3,3-tetrafluoro-1-propyl methacrylate-d ₅ are obtained. Yield 92.8%. bp93.5 ~ 95
℃ / 135mmHg. Refractive index: ▲ n ²⁰ _D ▼ = 1.3730. IR (neat):
1730 cm ^-1 Example 3. 1,1,1,3,3,3-hexafluoro-2-propyl methacrylate Synthesis Example of -d ₅ 1. of methacrylic acid chloride was synthesized in the same manner -
d _5, 63 g (0.57 mol) in 1,1,1,3,3,3-hexafluoro-2
-98 g (0.58 mol) of propanol was added, and after reacting at 82 ° C for 5 hours, 131 g of distillate obtained by distillation was washed with 100 ml of 10% NaHCO ₃ aqueous solution, washed with water, and then dried with 10 g of molecular sieves 4A, 86.5 g of 1,1,1,3,3,3-hexafluoro-2-propylmethacrylate-d ₅ are obtained. Yield 62.4%. bp94
~ 95 ℃ / 760mmHg. Refractive index: ▲ n ²⁰ _D ▼ = 1.3300. IR (nea
t): 1735 cm ^-1 Reference Example 1. synthesized in Example 1 of polymer for the core of the waveguide 2,2,2-trifluoroethyl methacrylate -d _5, 0.01 mol% of an azo di-tert-butane as a polymerization initiator, a chain transfer agent Add normal butyl mercaptan to 0.005 mol% and add 1 at 135 ℃.
A heat polymerization reaction was carried out for 2 hours, 160 ° C. for 3 hours, and 185 ° C. for 6 hours. The reaction product is treated and purified by a conventional method,
The target polymer was obtained (average molecular weight of the polymer: about 65,0
00, refractive index: 1410).

Reference Example 2. Using the polymer obtained in Reference Example 1 as a core material and octafluorobenthyl methacrylate (refractive index: 1.387) as a cladding material, an optical fiber was produced by a conventional method.

The result of measuring the loss spectrum of the obtained optical fiber is shown in FIG.

As is clear from FIG. 1, the optical fiber produced by using the polymer obtained in Reference Example 1 as the core material has 660 nm, 7
It can be seen that there are windows with low loss at 80 nm, 840 nm, 920 nm, etc.
However, low loss values at these wavelengths range from 100 to 2
Since it is about 00 dB / km, it can be seen that it can be used in a wider wavelength range than conventional plastic optical fibers [for example, in the case of optical fibers using polymethylmethacrylate (PMMA) -d ₅ as the core material. The loss value at a wavelength of 760nm is 210pB / km. ].

When an optical fiber is used for a waveguide, it is often used with a length of about 1 m. When the above optical fiber is used for this purpose, the loss value is 0.1
It is a low value of about 0.2 dB / m. Moreover, the loss value of the above optical fiber in the wavelength range of 1.3 μm is 1000 dB / km or less (for example, in the case of the optical fiber using PMMA-d ₈ as the core material, the loss in the wavelength range of 1.3 μm band). The value is about 3,000 dB / k
m. ), That is, 1dB / m or less, the optical fiber is extremely excellent for a waveguide, in other words, the polymer obtained from the monomer of the present invention is a polymer for a waveguide core. It turns out that it is extremely excellent.

Furthermore, after the optical fiber was allowed to stand for 100 hours under the conditions of 50 ° C. and 85% relative humidity, the loss spectrum of the optical fiber was measured again, and the increase of the loss value was about 10 dB / km ( for example in the case of an optical fiber in which the PMMA-d ₈ and the core material, increased in loss values under the same conditions is 150 780nm
dB / km. ). As is clear from this result, the polymer obtained by using the monomer of the present invention as a raw material has a property of low water absorption, and has extremely excellent properties as a waveguide. I understand.

[Brief description of drawings]

FIG. 1 shows the results of measuring the loss spectrum of the optical fiber prepared in Reference Example 2.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Riki Miyagawa 2090 No. 21 Kasahata, Kawagoe City, Saitama Prefecture (72) Inventor Hideo Takeuchi 113 No. 16 Ueto, Kawagoe City, Saitama Prefecture (56) Reference JP-A-60-19106 (JP, A) JP 60-260905 (JP, A) JP 58-154803 (JP, A) JP 57-51645 (JP, B1)

Claims (1)

[Claims] 1. A general formula [I] (In the formula, R ¹ and R ² represent a lower fluoroalkyl group or hydrogen, provided that at least one of R ¹ and R ² represents a lower fluoroalkyl group.) Monomer.