RU2118617C1 - Uv-solidified organosilicon composition for fibre light guide covering - Google Patents

Abstract

FIELD: technology of fibre light guide making, organic chemistry. SUBSTANCE: composition has prepolymer of the following general formula:

where a = 0.98-1.00; b = 0-0.03; n > 10 and R is -(CH₂)_mOCONHR¹ or -(CH₂)_mNHCONHR¹ where m - whole number from 1 to 20; R¹ is

where R² is -O(CH₂)₂OCOCR³=CH₂ or -OCH(CH₃)CH₂OCOOCR³=CH₂ and R³ is H or CH₃ at the following ratio of components: prepolymer 97-99.5 wt.-%, photoinitiating agent 0.5-3 wt.-%, and inhibitor 10-500 ppm. Composition is used for making light guide covered by shell made of organosilicon UV-solidified polymers. EFFECT: improved method of synthesis, improved quality of polymers. 1 tbl, 5 ex

Description

 The invention relates to a technology for the manufacture of optical fibers, in particular, optical fibers with shells made of organosilicon UV curable polymers.

 At present, organosilicon materials of the SIEL type (1), which are a composition consisting of a polyorganosiloxane having vinyl groups bonded to silicon and a polyorganosiloxane having Si-H groups, are used as reflecting and buffering shells of optical fibers. The curing of these materials occurs when heated in the presence of a platinum catalyst. Also known are materials of the SIEL type, which are cured by UV irradiation (2). Such a composition is a mixture of a vinyl-containing polyorganosiloxane and a mercaptoalkyl-containing polyorganosiloxane. Urethane acrylate polymers cured by UV irradiation and free of silicon are also widely used as buffer and protective shells of fiber fibers (3 prototype).

Each of the described compositions has its advantages and disadvantages. SIEL type materials have high resistance to heating and oxidation, high optical parameters (which is used to obtain reflective coatings) and satisfactory physical and mechanical properties (elongation> 100% and an elastic modulus of approximately 0.1 - 0.3 MPa). Moreover, these properties change little over a wide temperature range from -60 to +250 ^o C. However, materials that cure upon heating have a limited cure rate. UV-curable organosilicon materials cure faster, but their cure speed is still not comparable to UV-curable organic polymers and, in addition, compositions containing mercaptans have an unpleasant odor.

Urethane acrylate organic polymers, in contrast, have a very high cure rate. But the properties of the coatings obtained from them are highly dependent on temperature. At low temperatures (<-35 ^o C) they become very stiff, which leads to an increase in optical loss of the fiber, and at high (> 100 ^o C) - thermal degradation of polymers occurs. Thus, these materials do not ensure the operation of the fiber in the required temperature range.

Our composition is devoid of the disadvantages of the known solutions. The composition includes a (meth) acrylate-containing siloxane-urethane oligomer (prepolymer), photoinitiator and inhibitor. In this case, the oligomer of the following structure is used:
R (CH ₃ ) ₂ SiO - {[Si (CH ₃ ) ₂ O] _a - [SiCH ₃ RO] _b } _n Si (CH ₃ ) ₂ R,
Where
a = 0.98-1.00;
b = 0 - 0.03;
n>10;
R = - (CH ₂ ) _m OCONHR ¹ or - (CH ₂ ) _m NHCONHR ¹ ; Where
m is an integer from 1 to 20;
R ¹ = - (CH ₇ H ₆ ) NHCOR ² , - (CH ₂ ) ₆ NHCOR ² , -C ₁₃ H ₁₀ NHCOR ² , -C ₁₃ H ₁₈ NHCOR ² , -C ₁₀ H ₁₈ NHCOR ² ;
Where
R ² = —O (CH ₂ ) ₂ OCOCR ³ = CH ₂ or —OCH (CH ₃ ) CH ₂ OCOCR ³ = CH ₂ and R ³ = H or —CH ₃ .

 The ratio of substituted and unsubstituted units in the prepolymer is selected from the following experimentally established conditions.

 If the molar fraction “b” of the substituted units in the siloxane chain exceeds 0.03%, then the coating becomes too hard.

 At n <10, the composition becomes very viscous, and the resulting coating loses its elasticity.

 As the photoinitiator, the same compounds are used as in the photochemistry of carbon compounds. However, when choosing a photoinitiator, it should be taken into account that, along with a high quantum yield of the photolysis reaction of the photoinitiator, compatibility of the photoinitiator with organosiloxanes is also necessary. Examples of such photoinitiators include benzoin methyl ester (OIE), benzoin isobutyl ether (IBEB), diethoxyacetophenone (DEAF), dimethoxyphenylacetophenone (DMPAF), hydroxypropylacetophenone (GPAF). A photoinitiator is introduced into the composition in an amount of 0.5-3.0%, depending on the type of initiator. When the content of the photoinitiator is less than 0.5 wt.%, The curing rate is low, the composition is not technologically advanced. An increase in the amount of initiator in excess of 3.0 wt.% Does not lead to an increase in the curing rate, but can lead to a loss of transparency of the composition.

 Known antioxidants, such as hydroquinone, hydroquinone methyl ester (MEG), ionol, are used as an oxidation inhibitor. Phenothiazine and its derivatives are not suitable in this case, since the composition is stained, which makes it unsuitable for use as a fiber optic sheath. The amount of inhibitor is from 10 to 1000 ppm, optimally no more than 500 ppm, because the high content of the inhibitor significantly reduces the drawing speed of the fiber.

A distinctive feature of the invention is the qualitative composition of the prepolymer, i.e. the presence in it of both siloxane and urethane-acrylate parts, and this, in turn, provides both a high rate of vulcanization of these compounds in a dynamic mode (up to 150 m / min) and frost and heat resistance in the temperature range from -90 ^o C up to +150 ^o C.

 The specified distinguishing feature, as having a general novelty and contributing to the achievement of the technical result of the invention, is essential.

 Our proposed (meth) acrylate-containing siloxanurethane oligomers are obtained by reaction between an oligoorganosiloxane containing hydroxyl or amine functional groups with a urethane isocyanate in an optimally selected solvent in the presence of a catalyst and an oxidation inhibitor.

 The polymer sheath is applied to the quartz fiber according to the following scheme: the composition is poured into a thermostatically controlled tank of the spinneret assembly, and after filling the fiber into the spinneret, pressure is applied to the tank and argon in a UV illuminator. The composition is uniformly extruded from the die, applied to the fiber and, when it enters the UV illuminator, cures in an inert atmosphere. The exhaust installation is brought to the regulated speed and transferred to automatic mode.

 Examples 1-5 provide descriptions of the syntheses and preparation of photocurable compositions, as well as their properties in the cured state (see table). The above examples do not limit the scope of the invention.

 Example 1

 Preparation of the prepolymer.

800 g of α, ω-dihydroxypropylpolydimethylsiloxane (M.V. 8000) are added to a round-bottom flask equipped with a stirrer, nitrogen bubbler and dropping funnel, 67.6 (0.2 mol) of ethylene glycol acrylate adduct and isophorondiisocyanate adduct are added, 1.2 g are added dibutyltin dilaurate and the mixture was stirred at a temperature of 60 ^° C. until the isocyanate groups disappeared in the IR spectrum.

 Preparation of the composition.

 To 99.8 g (99.8 wt.%) Of the obtained product, add 0.2 g (0.2 wt.%) Of DMF, 0.1 g (1000 ppm) of ionol and irradiate with a DRT-230 lamp from a distance of 10 cm within 5 minutes.

 Example 2

 According to the procedure described in example 1, prepolymer 2 is prepared using 100 g of α, ω-dihydroxypropyl polyorganosiloxane containing 5 mol% γ-hydroxypropyl substituents in the main siloxane chain as starting materials (M.w. ≈ 10000) and 25, 6 g of ethylene glycol methacrylate adduct and hexamethylene diisocyanate.

 Preparation of the composition.

 95 g (95 wt.%) Of the obtained oligomer, 5 g (5 wt.%) Of IBEB and 0.002 g (20 ppm) of hydroquinone are mixed. Cure as described in example 1.

 Example 3

Prepolymer preparation
324 g of α, ω-dihydroxybutylpolydimethylsiloxane (M.V. 1300) and 150 ml of γ-butyrolactone are loaded into a flask equipped with a stirrer, reflux condenser and dropping funnel, and then 190 g (0.5 mol) of methylenebisphenyl diisocyanate adduct and ethylene glycol methacrylate are added in 150 ml of γ-butyrolactone. After adding 0.3 g of hydroquinone, the mixture was heated to 90 ^° C. and stirred until the isocyanate groups disappeared in the IR spectrum. After distilling off the solvent, a viscous clear liquid is obtained.

 Preparation of the composition.

 To 99.5 g (99.5 wt.%) Of the obtained product, add 0.5 g (0.5 wt.%) Of the OIE, 0.05 g (500 ppm) of hydroquinone.

 Example 4

 Preparation of the prepolymer.

In a round-bottom flask equipped with a stirrer, a nitrogen bubbler and a dropping funnel, 400 g of α, ω-diaminopropylpolydimethylsilolxane (M. century 4000) and 150 ml of 2-ethoxyethyl ether are placed. While purging with nitrogen and stirring, 76 g (0.2 mol) of the adduct of propylene glycol acrylate and methylenebisphenyl diisocyanate dissolved in 150 g of 2-ethoxyethyl ether are added while maintaining room temperature. Upon completion of the dropping, the mixture was heated to 50 ^° C and stirred for another 1 hour. After distilling off the solvent, a viscous, light yellow liquid is obtained.

 Preparation of the composition.

 97 g (97 wt.%) Of the prepolymer, 3 g (3 wt.%) Of DEAF and 0.02 g (200 ppm) of MEG are mixed.

 Example 5

 Preparation of the prepolymer.

250 g of α, ω-dihydroxymethylene polydimethylsiloxane (M.V. 2500), 100 g of toluene and 0.3 g of dibutyltin dilaurate are charged into a round bottom flask equipped with a stirrer, nitrogen bubbler, dropping funnel and reflux condenser. The mixture is heated to 30-40 ^° C. and a toluene solution of propylene glycol methacrylate adduct and 2,4-toluene diisocyanate adduct (63.6 g adduct in 100 g toluene) are added dropwise. Stirring is continued until the isocyanate groups disappear in the IR spectrum. Toluene is then distilled off under reduced pressure.

 Preparation of the composition.

 98.5 g (98.5 wt.%) Of the prepolymer, 1.5 g (1.5 wt.%) Of GPAA and 0.05 g (500 ppm) of ionol are mixed.

 Thus, as can be seen from the above data, the composition we have proposed due to the presence in one molecule of siloxane and urethane acrylate fragments has a unique combination of properties. On the one hand, the presence of large siloxane fragments gives the obtained material the thermal stability characteristic of polysiloxanes and a low glass transition temperature, which ensures operability in a wide temperature range, on the other hand, the introduction of urethane-acrylate groups into the side frame of siloxanes can significantly increase the cure rate, bringing it to the cure rate industrial urethane acrylates.

 Sources of information.

 1. A.S. USSR N 736769, class G 02 B 6/02, 1980.

 2. RF patent N 2002712 C1, cl. C 03 C 25/02, 1993.

 3. A.S. USSR N 1662089, class C 03 C 25/02, 1988.

Claims (1)

A UV curable organosilicon composition for coating optical fibers, including a prepolymer, a photoinitiator and an inhibitor, characterized in that a prepolymer of the following general formula is used:
R (CH ₃ ) ₂ SiO - {[Si (CH ₃ ) ₂ O] _a - [SiCH ₃ RO] _b } _n Si (CH ₃ ) ₂ R,
where a = 0.98 - 1.00;
b = 0 - 0.03;
h>10;
R = - (CH ₂ ) _m OCONHR ¹ or - (CH ₂ ) _m NHCONHR ¹ ,
where m = 1 - 20, an integer;
R ¹ - - (C ₇ H ₆ ) NHCOR ² , - (CH ₂ ) ₆ NHCOR ² , -C ₁₃ H ₁₀ NHCOR ² , -C ₁₃ H ₁₈ NHCOR ² , - C ₁₀ H ₁₈ NHCOR ² , where R ² - —O (CH ₂ ) ₂ OCOCR ³ = CH ₂ or —OCH (CH ₃ ) CH ₂ OCOCR ³ = CH ₂ and R ³ —H or —CH ₃ ,
in the following ratio of components, wt.%:
Prepolymer - 97.0 - 99.5
Photoinitiator - 0.5 - 3.0
Inhibitor, ppm ^-1 - 10 - 500f

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