RU2387634C1 - Oligo oxypropylene acrylates for primary layer of polymer coating of optical guides and synthesis method thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: described are oligo oxypropylene acrylates for the primary layer of polymer coating of optical guides based on oligo oxypropylene glycol with molecular weight over 1000 and functionality of 2-3 with fractional conversion of hydroxyl groups into acrylate groups equal to 80-90%. Also described is a method for synthesis of oligo oxypropylene acrylates, involving acrylation of hydroxyl oligomer groups with acryloyl chloride without a solvent or in a medium of a dry organic solvent in the presence of an aliphatic tertiary amine at temperature 10-30°C. The method is distinguished by that, the hydroxyl-containing oligomer used is oligo oxypropylene glycol with molecular weight over 1000 and functionality 2-3 with fractional conversion of hydroxyl groups to acrylate groups equal to 80-90%.

EFFECT: obtaining oligo oxypropyelene acrylates with low viscosity and glass transition point, suitable for making the primary layer of frost-resistant low-modulus polymer coatings of optical guides.

2 cl, 2 tbl, 7 ex

Description

The invention relates to photocurable non-urethane oligoester acrylates, the polymers based on which retain elasticity in a wide range of negative temperatures and can be used for the primary layer of a protective-hardening coating of optical fibers. They can also be used as active diluents in photocurable compositions.

In connection with the expansion of the scope of application of optical fibers to protective-hardening coatings, increasingly higher demands are made. The primary layer of the protective and hardening coating of the fiber must be flexible, that is, the material of this layer must have a low modulus of elasticity and not go into a glassy or crystalline state over the entire range of operating temperatures. In addition, the photocurable composition should have a viscosity of not more than 10 Pa · s.

It is known to use photocurable oligourethane acrylates obtained from flexible chain hydroxyl-containing oligomers for the primary layer of optical fibers, the hydroxyethyl acrylate molecules being grafted via diisocyanate to their terminal hydroxyl groups [Han D.K., Seung G.K., Chang S.H. Properties of UV-curable polyurethane acrylates for primary optical fiber coating // J. of Appl. Polym. Sci. - 1992. - Vol. 46 - P.1339-1351]. The presence of urethane groups leads to a sharp increase in intermolecular interaction in the oligomer due to the formation of hydrogen bonds. As a result, the glass transition temperature of the cured material and the viscosity of the oligourethane acrylate increase in comparison with the initial hydroxyl-containing oligomer. Due to the high viscosity, oligourethane acrylates, for application to the fiber, are diluted with volatile solvents or active diluents (low viscosity acrylates), which leads to an increase in the elastic modulus of the coating due to an increase in the crosslinking frequency in the cured material.

The use of urethane-free acrylate terminal oligomers should bring the frost resistance of coatings closer to that of the original flexible chain oligomers and remove the problem of viscosity of the curable composition.

Known urethane-free oligobutadiene acrylates synthesized based on oligobutadiene having low glass transition temperatures (up to -90 ° C) and moderate viscosity [F. Ferrero, G. Malucelli Synthesis of polybutadien-acrylates and properties of the photocured films // Progress in Organic Coatings. - 2005. - Vol. 54 - P.337-343]. For a fairly large set of synthesized oligobutadiene acrylates, information on viscosity and glass transition temperature is not given, as well as data on the mechanical properties of cured materials. The glass transition temperatures of cured pure (without diluents) oligobutadiene acrylates have a wide spread (from -35 to -73 ° C), not correlating with either the molecular weight or the functionality of oligobutadiene acrylates. There is no information about the possibility of their use in polymer coatings of optical fibers.

Known urethane-free oligoester diacrylates based on polyethylene glycol - PEGDA with molecular weights from 400 to 2000 [A.Priola, G. Gozzelino, F. Ferrero, G. Malucelli Properties of polymeric films obtained from u.v. cured poly (etilene glycol) diacrylates // Polymer. - 1993. - Vol. 34 - P.3653-3657; A.Priola, G. Gozzelino, F. Ferrero, G. Malucelli Investigation on the structure - property relationships for films obtained from UV curable coatings // Progress in Organic Coatings. - 1993. - Vol.22 - P.301-314]. PEGDA, like the original polyethylene glycol oligomers, mainly crystalline substances, and coatings based on them are also prone to crystallization.

Also known are polyurethane-based non-urethane oligoester acrylates - PPGDA with molecular weights of 400, 1000 and 1200 [A.Priola, G. Gozzelino, F. Ferrero, G. Malucelli Investigation on the structure - property relationships for films obtained from UV curable coatings // Progress in Organic Coatings. - 1993. - Vol.22 - P.301-314]. PPGDA do not crystallize and have sufficiently low glass transition temperatures. For cured PPGDA with a molecular weight of 400, the glass transition temperature is -49 ° C. For materials based on PPGDA 1000 and 1200, data on the glass transition temperature are not presented and the poor reproducibility of the results during their synthesis is indicated. Commercially available oligooxypropylene diacrylates with a molecular weight of not more than 800, used as active diluents in photocurable coatings. However, the low molecular weight of the oligomer corresponds to a high concentration of acrylate groups, which leads to an increase in the crosslink density in the cured material and an increase in its elastic modulus (i.e., material stiffness). Oligoxypropylene acrylates with such properties are not suitable for use as a primary layer of a protective-hardening polymer coating of optical fibers, since they do not have sufficient elasticity.

A known method for the synthesis of PEGDA and PPGDA by acrylation of the terminal hydroxyl groups of polyethylene glycol or polypropylene glycol with acrylic acid [A.Priola, G. Gozzelino, F. Ferrero, G. Malucelli Properties of polymeric films obtained from u.v. cured poly (etilene glycol) diacrylates // Polymer. - 1993. - Vol. 34 - P.3653-3657]. The synthesis is carried out in a dry organic solvent (benzene) in the presence of a stabilizer (hydroquinone), a catalyst (methanesulfonic acid) while boiling with azeatropic distillation of water. This reaction requires a long boil of the mixture (11 hours), and to prevent the polymerization of acrylates during the reaction, a large amount of stabilizer (hydroquinone) is introduced into the mixture. Hydroquinone and its oxidation products will interfere with photocuring in the future, and the purification of the oligomeric product from these impurities is difficult. Poor reproducibility of the results was noted in the synthesis of PPGDA with a molecular weight of already 1000.

If anhydride or acid chloride is used, the esterification can be carried out at temperatures of 0-30 ° C; in this case, the addition of radical reaction inhibitors is not required.

A known method of producing oligoester diacrylates by reacting an acid chloride of (meth) acrylic or α-chloroacrylic acid in a dry organic solvent in the presence of a tertiary amine or pyridine at 5-20 ° C in an inert gas atmosphere with diols of the general formula HO-R- (C≡C) _n -R-OH, where n = 2 or 4, R = -CH ₂ - or -CH ₂ -CH ₂ - [Copyright certificate SU 14087934 C08G 63/52. A method of producing oligoester acrylates. - BI 2000, No. 25. - S. 428].

This method is limited to the selection of certain diols.

The objective of the invention is the production of oligooxypropylene acrylates with low values of viscosity and glass transition temperature, suitable for the manufacture of the primary layer of frost-resistant low-modulus polymer coatings of optical fibers by photocuring.

To solve this problem, oligooxypropylene acrylates are proposed for the primary layer of the polymer coating of optical fibers based on oligooxypropylene glycols with a molecular weight of more than 1000 and a functionality of 2-3 with a degree of conversion of hydroxyl groups to acrylate 80-90%. A method for producing oligooxypropylene acrylates is proposed, which comprises acrylating the hydroxyl groups of the oligomer with acrylic acid chloride without solvent or in a dry organic solvent in the presence of an aliphatic tertiary amine at a temperature of 10-30 ° C, characterized in that oligoxyoxypropylene glycol is used as a hydroxyl-containing oligomer 2-3 functionality with a degree of conversion of hydroxyl groups to acrylate 80-90%.

Synthesized on the basis of oligooxypropylene glycols (laprols) oligooxypropylene acrylates have low viscosity and glass transition temperatures, therefore, they can be used to obtain the primary layer of frost-resistant low-modulus polymer coatings of optical fibers by photo-curing.

A method for producing oligooxypropylene acrylates by acrylating the hydroxyl groups of an oligomer with acrylic acid chloride has not been identified in the information sources. No description was also found of coatings of optical fibers obtained by photocuring of pure (without diluents) oligooxypropylene acrylates. This allows us to conclude that the proposed solutions meet the criteria of "novelty" and "inventive step".

Synthesis Method

Oligooxypropylene acrylates are obtained by reacting acrylic acid chloride (acryloyl chloride) with laprols in the presence of an aliphatic tertiary amine at a temperature of 10-30 ° C. The reaction is carried out both in a dry organic solvent and without it. To carry out the synthesis without a solvent, a mixture of a portion of acryloyl chloride with half a portion of dried laprol and a separate mixture of a portion of purified amine with the same amount of laprol are prepared. Then, the amine solution is gradually added in portions to the acryloyl chloride solution with stirring in a beaker using a mechanical stirrer while the beaker is cooled with water with ice or without cooling. After mixing, the reaction mixture is kept for 2-4 hours at a temperature of 20-40 ° C, then the tertiary amine hydrochloride is removed using one of the following methods:

- isolate the amine in free form under the action of an alkali solution (KOH or NaOH), then the amine is distilled from the reaction mixture,

- carry out the extraction of the amine into the aqueous phase in a neutral or acidic environment,

- solid amine hydrochloride is separated by filtration (centrifugation) of the reaction mixture diluted with an organic solvent that does not dissolve the amine salt (acetone, diethyl ether).

After purification from the amine hydrochloride, the solvent is removed from the product on a rotary evaporator, then the residual solvent and water are removed by evacuation using a water-jet pump at a bath temperature of 40-50 ° C.

The synthesis can also be carried out in a dry organic solvent. In this case, solutions of weighed portions of acryloyl chloride, tertiary amine and laprol are prepared in a solvent (for example, chloroform). Then, in a glass equipped with a magnetic stirrer and a thermometer, solutions of acryloyl chloride and amine are gradually added in portions to the laprol solution. After mixing, the reaction mixture is kept for 2-4 hours at a temperature of 20-40 ° C. Then, the solvent was removed from the reaction mixture on a rotary evaporator in a bath at a temperature of 50 ° C. Further, according to the above method.

The oligooxypropylene acrylates obtained are pale yellow liquids. The degree of conversion of hydroxyl groups to acrylate is 80-90% and is determined by the characteristic absorption band in the IR spectrum of 1200 cm ^-1 (vibrations of the single C — O bond in acrylate carboxyl associated with the secondary alcohol residue CH ₂ = CH — C (O ) -O-CH (CH ₃ ) - Calibration is carried out according to the IR spectra of solutions of sec-butyl acrylate of various concentrations in laprol.

The dynamic viscosity of the obtained oligomers is determined on a rotational viscometer "Reotest 2.1" with a working unit cone-plate at a temperature of 30 ° C (GOST 25276-82). The glass transition temperature is determined by differential scanning calorimetry on a DSC 822 ^e Mettler Toledo module.

Polymers are prepared by UV irradiation of a thin layer of synthesized oligomer in the presence of a photoinitiator. An equimolar mixture of benzophenone and tributylamine is prepared. To the weighed portion of oligoxypropylene acrylate add 6 wt.% Of the prepared mixture, mix. A small amount of the photocurable composition is placed in the gap between two glasses coated with a siloxane release agent. The thickness of the gap is 100 μm. As a source of UV radiation using a mercury lamp type PRK-2 with a capacity of 1000 watts. The distance from the lamp to the sample is 12 cm. The flux density of UV radiation in the range of 320-400 nm incident on the sample is 81-83 W / m ² (measured using a DAU-81 device). The minimum required exposure time for films is 6 minutes. The degree of completion of the photopolymerization reaction is assessed by PC spectroscopy on an IFS66 / S spectrometer (Bruker).

The glass transition temperature of the films is determined by differential scanning calorimetry on a DSC 822 ^e Mettler Toledo module. The tensile strength, elongation at break and the elastic modulus of the cured films are determined according to GOST 18299-72.

Example 1. Synthesis of oligooxypropylene diacrylate (PPGDA 1052) based on laprol 1052 (polypropylene glycol with M _n = 1050, with two terminal OH groups per molecule).

The components were taken in the following quantities.

Laprol 1052 - 10 g

Acryloyl chloride - 2.18 g

Triethylamine - 2.37 g

The synthesis was carried out according to the described method. To remove triethylamine hydrochloride, 23 ml of a 1 M aqueous KOH solution was added to the reaction mixture, stirred, and triethylamine with water was distilled off from the resulting emulsion to reach a boiling point of 100 ° С. 7 ml of acetone was added to the emulsion remaining in the distillation flask, the upper organic layer was separated in a separatory funnel, washed with distilled water, again defended in a separatory funnel, and the lower layer was collected. Water was removed by evacuation on a water-jet pump at a bath temperature of 40 ° C.

Example 2. Synthesis of oligooxypropylene diacrylate (PPGDA 2102) based on laprol 2102 (polypropylene glycol with M _n = 2100, with two terminal OH groups per molecule).

The components were taken in the following quantities.

Laprol 2102 - 10 g

Acryloyl chloride - 1.09 g

Tributylamine - 2.17 g

The synthesis was carried out according to the described method. After crystallization of tributylamine hydrochloride, the mixture was diluted with 40 ml of diethyl ether and filtered through a glass filter. Ether was distilled off from the filtrate in a water bath at a temperature of 50 ° С, then it was evacuated using a water-jet pump or rotary evaporator to remove ether residues.

Example 3. Synthesis of oligooxypropylene diacrylate (PPGDA 1052) based on laprol 1052.

The components were taken in the following quantities.

Laprol 1052 - 10 g

Acryloyl chloride - 2.17 g

N-methylmorpholine - 2.37 g

The synthesis was carried out according to the described method. 7 ml of acetone and 10 ml of water were added to the reaction mixture, shaken in a separatory funnel and settled. The upper layer was separated, washed with 30 ml of water and defended in a separatory funnel. The lower organic layer was collected and dried as in Example 1.

Example 4. Synthesis of oligooxypropylene diacrylate (PPGDA 2102) based on laprol 2102.

The components were taken in the following quantities.

Laprol 2102 - 10 g

Acryloyl chloride - 1.09 g

Tetramethylethylenediamine - 1.04 g

The synthesis was carried out according to the described method. A 10% hydrochloric acid solution was added to the reaction mixture with stirring until a rapid separation of the emulsion began. The organic layer was separated in a separatory funnel, washed with an aqueous solution of NaHCO ₃ , then with water. Settled in a separatory funnel until separation, collected the lower organic layer and dried, as in example 1.

Example 5. Synthesis of oligooxypropylene triacrylate (PPGTA 4503) based on laprol 4503 (polypropylene glycol with M _n = 4500, with three terminal OH groups per molecule) in solution.

The components were taken in the following quantities.

Laprol 4503 - 20 g

Acryloyl chloride - 1.62 g

Tetramethylethylenediamine - 1.77 g

Chloroform - 20 ml

The synthesis was carried out according to the described method. The solvent was removed from the reaction mixture on a rotary evaporator in a bath at a temperature of 50 ° C. The mixture was diluted with acetone, filtered through a glass filter, acetone was removed from the filtrate on a rotary evaporator under vacuum by a water-jet pump.

Example 6. Synthesis of oligooxypropylene triacrylate (PPGTA 5003) based on laprol 5003 (polypropylene glycol with M _n = 5000, with three terminal OH groups per molecule).

The components were taken in the following quantities.

Laprol 5003 - 20 g

Acryloyl chloride - 1.54 g

Triethylamine - 1.68 g

The synthesis was carried out according to the described method. The reaction mixture was diluted with 35 ml of acetone and centrifuged to precipitate triethylamine hydrochloride. The solution was drained from the precipitate and acetone was removed on a rotary evaporator, as in example 5.

Example 7. Synthesis of oligooxypropylene diacrylate (PPGDA 3502) based on laprol 3502 (polypropylene glycol with M _n = 3500, with two terminal OH groups per molecule).

The components were taken in the following quantities.

Laprol 3502 - 20 g

Acryloyl chloride - 1.27 g

Triethylamine - 1.39 g

The synthesis was carried out according to the described method. Further, as in example 6.

The test results of the obtained oligoxypropylene acrylates and cured polymer films are shown in tables.

The proposed solution has the following advantages compared to the prototype and analogues.

1. The simplicity of the synthesis process and the possibility of producing oligooxypropylene acrylates with large (more than 1000) molecular weights and a functionality of 2-3.

2. The synthesized oligooxypropylene acrylates have low viscosity values, so they can be used to obtain the primary layer of frost-resistant low-modulus coatings of optical fibers without the addition of diluents.

3. The polymers obtained by photo-curing oligooxypropylene acrylates are characterized by low glass transition temperature and elastic modulus (less than 10 MPa). The magnitude of the module can be varied by changing either the molecular weight of the original oligooxypropylene glycol or its functionality.

4. Availability of laprols used in the synthesis. These oligomers with varying molecular weights and functionality are produced on an industrial scale.

Table 1 Properties of the starting oligooxypropylene glycols and oligooxypropylene acrylates synthesized based on them Oligomer Glass transition temperature, ° С Dynamic viscosity according to GOST 25276-82, Pa · s Oligooxypropylene glycols Laprol 1052 -72 0.17 Laprol 2102 -71 0.3 Laprol 3502 -70 0.65 Laprol 4503 -70.5 0.57 Laprol 5003 -71 0.65 Oligooxypropylene acrylates PPGDA 1052 -73 0.21 PPGDA 2102 -72 0.36 PPGDA 3502 -71 1.16 PPGTA 4503 -70 0.7 PPGTA 5003 -70 0.62

table 2 Properties of cured oligooxypropylene acrylates Cured oligomer Breaking stress, MPa Elongation at break,% Modulus of elasticity, MPa Glass transition temperature, ° С PPGDA 1052 1,03 13 8.5 -55 PPGDA 2102 0.7 25 3.3 -58 PPGDA 3502 0.85 70 1,6 -64 PPGTA 4503 0.53 55 1.4 -65 PPGTA 5003 0.81 55 2.6 -65.5

Claims (2)

1. Oligooxypropylene acrylates for the primary layer of polymer coating of fibers based on oligooxypropylene glycols with a molecular weight of more than 1000 and a functionality of 2-3 with a degree of conversion of hydroxyl groups to acrylate 80-90%. 2. A method of producing oligooxypropylene acrylates, comprising acrylating the hydroxyl groups of an oligomer with acrylic acid chloride without a solvent or in a dry organic solvent in the presence of an aliphatic tertiary amine at a temperature of 10-30 ° C, characterized in that oligoxyoxypropylene glycol is used as a hydroxyl-containing oligomer with more than 1000 and 2-3 functionality with a degree of conversion of hydroxyl groups to acrylate 80-90%.