RU2509087C2 - Method of producing polyester acrylates - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: described is a method of producing polyester acrylates by polymerising an ester acrylate monomer under the effect of a physical factor, characterised by that the physical factor used is UV radiation with wavelength of 190-360 nm and an electromagnetic field with strength H>1500 Oe, which cyclically acts on the monomer placed in a transparent vessel; the monomer is subjected to thermal cycles in a temperature range of -50°C to +50°C, followed by further polymerisation at room temperature.

EFFECT: high quality of polymers, high optical transparency, high thermal stability and fewer labour-consuming operations.

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Description

The alleged invention relates to the chemistry of polymers, specifically to methods for producing block polyester acrylates, and can be used as light-transmitting matrices in optics, lighting technology and medicine, specifically for the production of implants.

The relevance of the problem to be solved is based on the need of modern technologies for optical materials with high density and optical parameters.

The ability of ester acrylates to form macromolecular compounds is associated with the presence of two reaction centers in the molecule: a double bond and active hydrogen atoms in the α and β positions.

Traditional methods for producing polymers are the use of chemical initiators, such as peroxides, azo and diazo compounds during heating, photolysis, radiolysis, etc., which negatively affect the property of the finished material (gel effect), which is characterized by the presence of bubbles in the mass of products ( VN Kuleznev, VA Shershnev, “Physics and Chemistry of Polymers”, M., “Higher School”, 1988, pp. 20-25).

In the proposed method of polymerization, this disadvantage is eliminated.

A known method of producing polymethylmethacrylate block polymerization in the presence of initiators. At the beginning of the polymerization process, a “syrup” is obtained, which is formed by prepolymerization of the monomer in the presence of an initiator in an amount of 0.05–0.1% of the mass, at 70–80 ° C for two hours with gentle stirring. The resulting "syrup" is poured into silicate glass molds and additionally polymerized with a gradual increase in temperature from 45 ° C to 120 ° C for 24-28 hours ("Technology of plastic masses", edited by V.V. Korshak, M., ed. Chemistry, 1985, pp. 125-127. F. Bilmeyer, "Introduction to the Chemistry and Technology of Polymers", M., ed. Foreign Literature, 1958, p. 311).

The disadvantages of this method are the length of the polymerization process, which consists in obtaining a prepolymer and additional polymerization at high thermal conditions. In addition, due to the high reaction rate, low thermal conductivity of the polymer, high viscosity of the reaction medium, complete removal of the reaction is difficult. A sharp increase in temperature inside the unit leads to local overheating, which causes bubbles to form in the products.

As the closest in technical essence and result to the claimed method, a method for producing oriented organic glass by polymerization of an ether acrylate monomer under the influence of a physical factor is known. As a physical factor, a low-frequency low-induction magnetic field with a frequency of not more than 1 kHz in the local zone of not more than 20 mT is used, which acts on a monomer placed in a dilatometer made of optically transparent glass, which is placed along the longitudinal axis of the solenoid of the magnetic installation, while carry out a cascade of at least 3 cycles of 10 minutes each with an interval between each cycle of at least 10 minutes, and polymerization is carried out without the use of catalysts, after which a dilatometer with called polymer is removed from the solenoid and left for depolymerization in the open air at room temperature (p. RU No. 2367669, publ. 09/20/2009).

The disadvantage of this method is the incomplete removal of residual monomer (% MMA - 1.1 ÷ 0.8), which negatively affects the light guide matrix.

The authors' task is to develop a method for the polymerization of polyether acrylates by eliminating the chemical initiators of polymerization, to obtain transparent defect-free polyether acrylates, to reduce the amount of toxic residual monomer, to increase heat resistance and light transmission.

A new technical result provided by using the proposed method, which consists in improving the quality of finished polymers by eliminating the defect of its structure, increasing optical transparency, increasing thermal stability and reducing the number of time-consuming operations.

These tasks and a new technical result are ensured by the fact that, in comparison with the prototype, UV radiation and an electromagnetic field are used as physical factors, which cyclically act on the monomer placed in a transparent vessel, thermally cycle in the temperature range from -50 ° C to + 50 ° C, after which the prepolymerization is carried out at room temperature.

The proposed method is illustrated as follows.

Initially, monomers are selected from the group of ester acrylates characterized by the presence of active centers.

The hypothesis of the effects of electromagnetic fields and UV irradiation is based on new principles of controlling molecular processes and chemical reactions and is associated with the selectivity of these processes to the angular momentum of molecules and the angular momentum-spin of the electron and nuclei of the reacting particles. Changes in the angular momentum are induced by magnetic interactions and, therefore, have a spin nature. The rates of spin-selective processes depend on external electromagnetic fields and UV irradiation and are found in photosynthesis, radical chemical reactions, in processes involving oxygen molecules and allow the production of improved quality products with predetermined properties.

Etheriracrylate is treated with UV radiation (190–360 nm), since activation of double bonds, their breaking and formation of active radicals at several wavelengths are observed in the indicated range. The following treatment with electromagnetic fields with intensity H> 1500 Oersted leads to the polymerization of ester acrylates with the formation of an ordered structure and a denser packing. In an electromagnetic field with intensity H <1500 Oersted, this was not observed.

The thermal cycling temperature range was chosen in accordance with the fact that at temperatures above + 50 ° C a sharp increase in the vapor pressure of MMA is observed, the monomer evaporates, and at temperatures below -50 ° C crystallites form in the product’s volume, i.e. instead of polymerization, a crystallization process is going on.

The essence of the alleged invention is as follows.

Industrial monomer (methyl methacrylate MMA) TU VP-156-68 or “syrup” containing from 10 mph up to 40 mph polymer per 100 m.h. methyl methacrylate is placed in a transparent vessel, treated with UV radiation, then with an electromagnetic field, thermal cycling is carried out. Then it is additionally polymerized at room temperature.

The content of residual monomer was determined by the bromide-bromate method (V. A. Balandina, DB Gurvich “Analysis of polymerization plastics”, M.-L., Chemistry, 1965, p. 512).

The melting point was determined using a laboratory device PTP-1. The determination error was ± 0.01 ° C.

Example 1

In the laboratory, we carry out the process of producing polyester acrylate. At the preliminary stage, a monomer sample was prepared according to the traditional method.

To do this, 0.10 mg of initiator (benzoyl peroxide (PB) GOST 14888-78) is added to 100 mg of methyl methacrylate (TU 8P-156-68), poured into a dilatometer, 10-15 minutes. purge with an inert gas, carry out polymerization for 6 ÷ 70 hours. During polymerization, the formation of bubbles in the block was observed. Physico-chemical studies showed the following:% residual monomer - 2.3; % initiator - 0.02; t _square - 251.7 C; light transmission - 89-91; % ρ - 1.206 g / cm ³

Comparative data on physico-chemical tests are carried out in table 1.

Example 2

MMA in an amount of 8.5 + 9 g is poured into a dilatometer, 10-15 minutes. purge with an inert gas and placed in a low-frequency magnetic field of low intensity. The polymerization took place without shrinkage and the formation of bubbles in the volume. Processing and all physico-chemical studies were carried out analogously to example 1.

Physico-chemical studies showed the following:% residual monomer - 0.8 ÷ 1.1; t _square - 252.5 ° C, light transmission - 91 ÷ 92%, ρ - 1.222 g / cm ³ . Comparative data on physico-chemical tests are carried out in table 1.

Example 3

Methyl methacrylate (TU 8P-156-68) in an amount of 1.5 ÷ 2 ml is poured into a transparent vessel, flushed with an inert gas, treated with UV radiation (190 ÷ 360 nm), then with an electromagnetic field) of intensity H> 1500 Oersted, thermocycling is carried out in temperature range from -50 ° C to + 50 ° C. Then it is additionally polymerized at room temperature. The following data were obtained:% residual monomer — absent, t _pl. - 253.5 ° C, light transmission - 99.7 ÷ 99.9%, ρ - 1.249 g / cm ³ . Comparative data on physico-chemical tests are given in table 1.

Example 4

Ethyl methacrylate is obtained under laboratory conditions by the esterification of methacrylic acid (TU 6-09-1708-19) and ethyl alcohol (GOST 18300-87), taken in a ratio of 1.65: 1 mg. H ₂ SO _{4 was} used as an absorber of released water ( GOST 4204-77) followed by distillation of the resulting ethyl methacrylate (EMA).

The obtained EMA in an amount of 1.5–2.0 ml is placed in a transparent vessel, purged with an inert gas, treated with UV radiation (190–360 nm), and with an electromagnetic field with an intensity of H> 1500 oersted cyclically at least 3 times. Then carry out thermal cycling in the temperature range from -50 ° C to + 50 ° C. The prepolymerization is carried out at room temperature. The following data were obtained:% residual monomer — absent, t _pl. - 254 ° C, light transmission - 98.5 ÷ 99.0%, ρ - 1,300 g / cm ³ . Comparative data on physical and chemical tests are given in table 1. The results of experimental tests are shown in table 1.

Table 1. No. p / p Sample, polymerization method Polymer state Chemical characterization physical characteristics % MMA Initiator t _square Light transmission.% ρ, g / cm ³ one MMA + 0.1% PB Transparent, fragile, gel effect is observed 2,3 0.02 251.7 88-91 1,206 2 MMA, low-frequency low-intensity magnetic field Transparent, solid, no bubbles in volume 1.1 ÷ 0.8 - 252.5 91-92 1,222 3 MMA, exposure to UV radiation, an external electromagnetic field, thermal cycling Transparent, solid, no bubbles in volume - - 253.5 99.7-99.9 1,240 four PEA, cascading UV irradiation, external electromagnetic field, thermal cycling Transparent, solid, no bubbles in volume - - 254 98.5-99.0 1,300

Thus, in the proposed method of polymerization, the initiators of free radical polymerization are UV radiation and an electromagnetic field.

Carrying out thermal cycling in the t range from -50 ° C to + 50 ° C leads to a more durable polymer structure. At the same time, physicochemical characteristics are improved: light transmission increases by 8%, heat resistance increases by 0.4%, density is more than 1%, and there is no residual monomer. In addition, this polymerization method contributes to the production of defect-free products with good light transmission. The method is implemented with fewer operations, less energy intensive.

Claims (1)

A method of producing polyester acrylates by polymerization of an ether acrylate monomer under the influence of a physical factor, characterized in that UV radiation with a wavelength of 190 ÷ 360 nm and an electromagnetic field of H> 1500 Oe are used as a physical factor, which cyclically act on a monomer placed in a transparent vessel thermocyclic in the temperature range from -50 to + 50 ° C, after which the prepolymerization is carried out at room temperature.