RU2699100C1 - Method of producing aqueous epoxy dispersion - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to production of direct aqueous epoxy dispersions intended for use as film-former in compositions, for example, lubricants for inorganic (glass and basalt) and carbon fibers, soil-impregnation, component of protective-decorative water-dispersed coatings. Water emulsion is obtained by direct dispersion of epoxy resin with epoxy equivalent of 400 g/eq. up to 2,500 g/eq. in an aqueous solution of a surfactant. Epoxy resin is first converted into a liquid state by heating above the softening temperature and / or combination with an organic solvent. Surfactants used are surfactants selected from a group consisting of a block copolymer of ethylene oxide and propylene oxide and / or a polycarboxylate ester (copolymer of acrylic polycarboxylate and polyethylene glycol). Composition is obtained at the following component ratio, pts.wt.: epoxy resin : block copolymer of ethylene oxide and propylene oxide : polycarboxylate ester : water = 100:(4–15):(0–10):(70–160).

EFFECT: technical result of the invention is the possibility of using the method when dispersing solid epoxy resins on an industrial scale, obtaining aqueous epoxide dispersions with high colloidal-chemical stability, which are controlled in a wide range of content of a dry residue and viscosity, which form a thin non-sticky film when deposited on a fiber.

3 cl, 2 tbl, 12 ex

Description

The invention relates to methods for producing aqueous epoxy dispersions intended for use as a film-forming component of lubricants for inorganic (glass and basalt) and carbon fibers, a binder for protective-decorative and anticorrosion paints, primers, water-dispersion coatings, etc.

A known method of producing an epoxy emulsion (RF patent No. 2154081, C09D 163/02, C09D 5/02, Bull. No. 22 from 08/10/2000), comprising combining an epoxy resin with a nonionic emulsifier with a hydrophilic-lipophilic balance (HLB) 14-20 and / or an anionic emulsifier at 51-79 ° C followed by portioned administration of water. As a result, homogeneous emulsions are obtained, which are used to obtain decorative protective coatings, primers, etc., which have high atmospheric resistance and corrosion resistance.

The disadvantages of the proposed method is a rather short shelf life (3-6 months) and mainly a large particle size.

In terms of technical nature and the achieved results, the closest is the method of producing an aqueous epoxy emulsion (RF patent No. 2587091, C09D 5/02, C09D 163/00, C09D 163/02, Bull. No. 16 dated 06/10/2016, prototype) by direct epoxy emulsification low molecular weight resin (liquid) with an epoxy weight equivalent of up to 300 g / eq. in an aqueous solution of surfactants containing a polycarboxylate ester and a copolymer of ethylene oxide and propylene oxide, as well as additional silica sol.

The resulting emulsions are characterized by stability and colloidal chemical stability, high dispersion — the average particle size is from 0.2 to 0.6 microns.

The disadvantages of the proposed method are:

- the inability to use the method in the dispersion process of medium and high molecular weight resins with a higher epoxy weight equivalent;

- the inability to obtain aqueous emulsions with an average particle size of more than 0.6 microns.

The particle size of the film former affects the increase in the degree of sizing in the manufacture of inorganic fibers. Fibers are subjected to significant mechanical stresses during production and further processing (in this case, the film-forming layer on the fiber protects the fiber from abrasion), for example, by trimming and manufacturing assembled fibers with high linear density.

An object of the present invention is to remedy the aforementioned disadvantages. The technical result is the achievement of optimization of the formulation and technological parameters of the method for producing aqueous epoxy dispersions, which ensures the production of a disperse phase with a particle size of 0.2 to 1.2 μm and high colloidal chemical stability of the polydisperse system for a long time (1-2 years) at storage.

The technical result is achieved by creating a method for producing an aqueous epoxy dispersion by direct dispersion of an epoxy resin with an epoxy weight equivalent of 400 g / eq. up to 2500 g / equiv., previously converted into a liquid state by heating above the softening temperature, in an aqueous solution of surfactants selected from the group consisting of a block copolymer of ethylene oxide and propylene oxide and / or a copolymer of acrylic polycarboxylate and polyethylene glycol in the following ratio of basic components (parts by weight):

Epoxy resin 100 Block copolymer of ethylene oxide and 4-15 Propylene oxide Acrylic Polycarboxylate Copolymer 0-10 and polyethylene glycol Water 70-160.

The method provides stable storage during storage of aqueous dispersions of medium and high molecular weight epoxy resins with a broad controlled range of solids, fineness and viscosity, which ensures the formation of non-sticky films upon application to the fiber.

The use of medium and high molecular weight epoxy resins, optimized dispersion production regimes, and the inclusion of an organic solvent in a number of compositions made it possible to obtain film formers with an average particle size of 0.2 to 1.2 μm.

It is advisable to introduce an organic solvent in an amount of 5.0-25.0 wt.% In a heated liquid epoxy resin. hours per 100 wt. including epoxy resin.

An organic solvent mixes epoxy with an aqueous solution of surfactants at lower temperatures (compared to their softening temperature).

It is preferable to use an organic solvent with a boiling point exceeding the softening temperature of the epoxy resin by at least 30-40 ° C to minimize the harmful effects on production personnel and prevent intense evaporation.

A causal relationship between the totality of the features of the invention and the technical result achieved is:

- firstly, in comparison with the analogue, the range of used epoxies has been expanded - it includes medium and high molecular weight solid epoxies with a higher epoxy weight-equivalent, an organic solvent is included in some formulations;

- secondly, to implement the method of producing dispersions of solid and semi-solid resins (without or with a minimum content of organic solvent), a heating system and supply of highly viscous liquids was used, including a heated plate, pump and heated hoses or pipe;

- thirdly, the introduction of organic solvents with a high boiling point into resins heated above the softening temperature makes it possible to disperse high molecular weight epoxy resins in an aqueous surfactant solution with the formation of direct stable dispersions;

- fourthly, in that the use of an organic solvent and polycarboxylate ester as a coemulsifier allows you to adjust the pH of the resulting products in a fairly wide range and increase their dispersion and stability.

The combination of all the essential features of the invention and the technological regimes given in the examples described below provides the universality of the process for preparing stable dispersions (based on various types of resins), characterized by a wide range of variation of the dry residue and viscosity, and a change in the average particle size from 200 nm to 1.2 μm , a change in the pH level from acidic to slightly alkaline, providing the formation on the surface of the fibers of non-sticky films of various degrees of hardness (table 2).

The following components were used to obtain aqueous dispersions of epoxy resins:

- as a base (dispersed phase) - medium and high molecular weight epoxy resins with an epoxy equivalent molecular weight (EEW) of about 400 to 2000-2500 g / eq, for example, Russian resin under the brand name ED-8 from FKP Plant Name Ya.M. Sverdlova ”, imported resins under the trademarks Epikote 1002, Epikote 1007 and others from Hexion Inc. (formerly Momentive, USA), DER 671, DER 692 from Olin (formerly Dow Chemical), NPES -601, NPES-602, NPES-603, NPES-604, NPES-901, NPES-607, NPES-609 from NanYa Plastics Corp. (Taiwan), YD-011, YD-012 from Kukdo Chemical) ) (South Korea), CHS-Epoxy 211, CHS-Epoxy 112 from Spolchemie (Czech Republic), etc .;

- as non-ionic surfactants - a block copolymer of ethylene oxide and propylene oxide with a content of polyoxyethylene units from 78 to 85 mass% and HLB above 14.0, as a co-emulsifier - a copolymer of acrylic polycarboxylate and polyethylene glycol under the Ethacryl brand (manufacturer - “Coatex ”, France);

- as an organic solvent, diacetone alcohol (Diacetone alcohol - DAA), propylene glycol methyl ether (methoxypropanol) (propylene glycol methyl ether - PGME), ethylene glycol propyl ether (2-propoxyethanol) (ethylene glycol propyl ether - EGPE). The introduction of an organic solvent allows you to: dissolve semi-solid epoxy resins and ensure their processing at lower temperatures (compared with their softening temperature); to obtain more finely dispersed systems (with a smaller average particle size); provide an increase in the processability of the process - on average, the mixing time of components during emulsification is reduced by 20-30%. Stable concentrated dispersions of high molecular weight epoxy resins can be obtained as described below only using an organic solvent.

Examples of compositions of aqueous dispersions are shown in table 1, and their characteristics are shown in table 2.

Examples 1-9. Obtaining aqueous dispersions of medium molecular weight solid epoxy resins or mixtures thereof with semi-solid resins with a total epoxy weight equivalent (EEW) of 400 ÷ 1000 g / equiv.

First, a 20% solution of the main surfactant, a block copolymer of ethylene oxide and propylene oxide, is prepared. When preparing the solution, distilled water with a temperature of +18 to + 35 ° С is used (increasing the temperature from + 18 ÷ + 20 ° С to + 30 ÷ + 40 ° С leads to an acceleration of the process of dissolution of the block copolymer of ethylene oxide and propylene oxide in water). In the case of using two surfactants (formulations 2, 3, 5, 7, 9), a copolymer of acrylic polycarbonate and polyethylene glycol (polycarboxylate ether) is introduced into a 20% solution of a block copolymer of ethylene oxide and propylene oxide.

An epoxy resin is dosed into a previously prepared surfactant solution with constant stirring using a high-temperature material supply system. Dosing of solid resin is carried out at a temperature above its softening temperature by 5-15 ° C (70 ÷ 110 ° C). The Brookfield viscosity of the epoxy at dosing is not more than 25,000 mPa × s.

In the presence of an organic solvent in the formulation (formulations 4, 5, 8, 9), it is introduced into a heated liquid epoxy resin. With the introduction of an organic solvent in an amount of up to 10-15 mass. hours per 100 mass. including resin the temperature of the supplied resin can be reduced by 20-40 ° - up to 40 ÷ 80 ° C.

The viscosity of the supplied resin / resin solution is determined, including the amount of solvent introduced (if present), and the temperature of the resin. After loading the epoxy resin, the dispersion is carried out at a speed of 1000-4500 rpm (peripheral speed should be at least 20 m / s, preferably from 25 to 40 m / s) for 10-30 minutes The viscosity of the resin melt / resin melt solution (indicated in the examples) determines the processability of the dispersion process (a product with a higher viscosity is harder to pump and disperse at a specified speed). A decrease in peripheral speed to 20 m / s and less will not allow to obtain a dispersion with a particle size of less than 1 μm).

Further, the polydisperse system can be diluted with water to the required concentration (as a rule, the solids content in these systems is from 45 to 65%). After adding water, the dispersion is mixed for at least 20-25 minutes at a speed of up to 1000 rpm.

Examples 10-12. Aqueous dispersions based on high molecular weight solid epoxy resins with EEW = 1500 ÷ 2500 g / equiv.

These dispersions are obtained by the method described for the examples with an organic solvent (4, 5, 8, 9). The Brookfield viscosity of the epoxy solution at dosing is not more than 20,000 mPa × s. Given the higher softening temperature of the used resins (100 ÷ 135 ° C) in these systems, it is necessary to use solvents with a higher boiling point, for example, diacetone alcohol DAA (T ° _bp ~ 170 ° C). The temperature of the solution of high molecular weight epoxy at dosing is 50 ÷ 80 ° C).

At the stage of introducing the resin into the aqueous surfactant solution, the amount of water is determined by obtaining highly concentrated dispersions with a solids content (mass fraction of non-volatiles) of at least 60%.

After loading all the components, the dispersion is carried out at a speed of 2000-4500 rpm (peripheral speed should be at least 20 m / s, preferably from 25 to 40 m / s) for 10-30 minutes.

The polydisperse system can also be diluted with water to the required concentration (as a rule, the solids content in these systems is from 40 to 55 wt.%).

From the results presented in table 2 it is seen that the described methods for producing aqueous dispersions of epoxy resins allowed to obtain dispersions that are non-sticky when dried, and in the case of using resins with EEW> 650 g / equiv. - hard films.

Dispersions based on solid epoxies with EEW = 400 ÷ 700 g / equiv., Obtained in examples 1-5, can be recommended for use as film formers in sizing compositions for the production of continuous roving for composite materials based on thermosetting binders (epoxy, vinyl ester) polyester). At the same time, the use of resins with a higher EEW will increase the strength of roving-based composites with this film former.

Dispersions based on medium and high molecular weight solid epoxy resins with EEW = 650 ÷ 2000 g / equiv. can be recommended for the production of chopped roving for filling thermoplastic binders.

The resulting dispersions are characterized by a dry residue of 45 to 70%, stability, a wide range of dispersion changes - the average particle size varies from 200 nm to 1.2 μm, viscosity (depending on the dry residue and dispersion, Brookfield viscosity varies from 200 MPa × s to 80,000 mPa × s), pH (from 3.0 to 9.0).

The use of dispersions with pH = 3-6 may be of interest for sizing compositions containing components having an acidic environment and prone to rapid delamination when combined with a slightly alkaline film former.

The shelf life depends on the composition and characteristics of the dispersions and ranges from 9-12 to 24 months.

Thus, the use of the proposed compositions and technological methods of obtaining allows us to obtain stable dispersions of various concentrations with good colloidal chemical stability (sedimentation and aggregative), various degrees of hardness of a non-sticky film (after solvent removal), which expands the field of application of film formers in the compositions of sizing compositions for inorganic and carbon fibers.

Claims (4)

1. A method of obtaining an aqueous epoxy dispersion by direct dispersion of an epoxy resin with an epoxy weight equivalent of 400 g / eq. up to 2500 g / equiv., previously converted into a liquid state by heating above the softening temperature, in an aqueous solution of surfactants selected from the group consisting of a block copolymer of ethylene oxide and propylene oxide and / or a copolymer of acrylic polycarboxylate and polyethylene glycol, in the following ratio main components (parts by weight): Epoxy resin 100 Block copolymer of ethylene oxide and propylene oxide 4-15 Acrylic Polycarboxylate Copolymer and polyethylene glycol 0-10 Water 70-160 2. The method according to p. 1, characterized in that the organic solvent is introduced into the heated liquid epoxy resin in an amount of 5.0-25.0 wt. hours per 100 wt. including epoxy resin. 3. The method according to p. 2, characterized in that they use an organic solvent with a boiling point exceeding the softening temperature of the epoxy resin by at least 30-40 ° C.