RU2674137C1 - Method for obtaining biocidal water-dispersion varnish and paint materials - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the field of production of water-dispersion paints and varnishes (WD-PV) containing a biocidal additive of silver nanoparticles, and can be used to obtain paints and varnishes for interior decoration. Water-dispersion paint material is prepared on the basis of the pigment paste obtained by dispersing pigments and fillers with a mass fraction of water-soluble substances not more than 0.1 %, degree of dispersibility up to 10 microns, zeta potential less than -25 mV and having pH of 7.5–8.5, which is mixed with anion-active acrylic polymer dispersion with a particle size of up to 0.1 micron, then adjust the pH level to 7.5–8.5 with ammonia solution, and mixing with a biocidal additive nanoparticles of silver with pH of 7.5–8.5, an average particle size of from 10 to 100 nm and using anion-active or non-ionic surfactants in its composition is carried out in a dissolver at cutter speeds of 40–70 rpm.

EFFECT: invention ensures the preservation of biocidal behavior with a reduced content of the biocidal additive of silver nanoparticles up to 1½ mcM per 1 kg of WD-PV.

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Description

The invention relates to the paint industry, in particular, to the field of water-dispersed paint materials (VD-LKM) containing a biocidal additive of silver nanoparticles, and can be used to produce paint and varnish materials for interior decoration.

The prior art method for producing organic paints and varnishes described in the patent [RU 2195473 "Paints and varnishes with biocidal properties", 03/07/2002 Bull. No. 36 dated December 27, 2002], which includes the traditional method: obtaining pigment paste in a high-speed dissolver, then dispersing it in a bead mill to the desired degree of grinding, mixing with the remainder of the binder, introducing functional additives.

The disadvantage of this method is the high concentration of biocidal additives of silver nanoparticles, the lack of control of the pH of VD-LKM, the content of water-soluble substances and their allocation during dispersion of pigments and fillers (to ensure the aggregate stability of silver nanoparticles in VD-LKM).

Closest to the proposed invention, adopted as a prototype, is a method for producing paints and varnishes based on a water-borne styrene-acrylic polymer (A-10) together with a hydrocarbon solution (isooctane), described in patent [RU 2186810 "Composition with bactericidal properties", 20.07. 2000 bul. No. 22 August 10, 2002. Example 1]. The introduction of silver nanoparticles ranging in size from 2 to 100 nm is carried out portionwise directly into the paint at low speeds from 50 to 700 rpm

The disadvantage of the prototype is the high concentration of the introduced biocidal additives up to 10 μm per 1 kg of paintwork, the lack of control of any physico-chemical parameters of VD-paintwork. The use of styrene-acrylic polymer dispersion A-10 and the introduction of toxic isooctane causes a partial agglomeration of nanoparticles, which increases the concentration of the added additive necessary to achieve the desired biocidality.

The problem to which the invention is directed, is to obtain biocidal VD-LKM with low cost by reducing the concentration of biocidal additives of silver nanoparticles to 1.5 μm per 1 kg of VD-LM.

This is achieved by the fact that the method of producing biocidal water-dispersion paints and varnishes involves mixing VD-LKM with a biocidal additive of silver nanoparticles. Water-dispersion varnish and paint material is prepared on the basis of pigment paste obtained by dispersing pigments and fillers with a mass fraction of water-soluble substances of not more than 0.1%, a degree of dispersibility of up to 10 μm, a zeta potential of less than -25 mV and having a pH of 7.5-8 , 5, which is mixed with an anionic acrylic polymer dispersion with a particle size of up to 0.1 μm, then the pH level is adjusted with an ammonia solution to 7.5-8.5, and mixing with a biocidal additive of silver nanoparticles is carried out in a dissolver at low rotational speeds of the cutter 40 - 70 rpm

Component Feature:

- the biocidal additive of silver nanoparticles is presented in the form of an aqueous solution made in accordance with TU 9392-003-44471019-2006, TU 2499-002-17826000-2013 or similar requirements: average size of silver nanoparticles in the range from 10 to 100 nm, pH = 7.5-8.5, used surfactant: anionic or nonionic.

- anionic acrylic polymer dispersion is used in accordance with GOST 11772-73 with a particle size of up to 0.1 microns;

- pigments and fillers are used with a mass fraction of water-soluble substances of not more than OD% according to GOST 21119.2-75, dispersibility up to 10 microns according to GOST R 50563.1-93, pH = 7.5-8.5 according to GOST 21119.3-91, zeta potential less -25 mV according to GOST R 8.887-2015 or GOST 8.653.1-2016;

- ammonia solution according to GOST 3760-79;

- the water used in the preparation of pigment paste complies with GOST 6709-72.

The research results showed that when using the developed method for producing biocidal VD-LKM, it is necessary to observe the set of experimentally obtained characteristics of the components: biocidal additive of silver nanoparticles with a pH of 7.5-8.5, an average particle size of 10 to 100 nm, and using in its composition anionic or nonionic surfactants; anionic acrylic dispersion with a particle size of up to 0.1 microns; pigments and fillers with a zeta potential of less than -25 mV, with a content of water-soluble substances of not more than 0.1%, dispersibility up to 10 microns, pH of 7.5-8.5. When deviating from the listed characteristics of the components used, biocidal properties do not appear.

In the proposed invention, a method for producing biocidal water-dispersion paints and varnishes includes the following stages:

1. Obtaining pigment paste by dispersing pigments and fillers with a mass fraction of water-soluble substances of not more than 0.1%, dispersible to 10 microns, pH = 7.5-8.5, zeta potential of less than -25 mV in water at a rotational speed of the dissolver cutter 1500-2000 rpm;

2. The preparation of VD-LKM by mixing the pigment paste with anionic acrylic dispersion at a rotational speed of the cutter of the dissolver 300-700 rpm;

3. Correction of the pH level of VD-LKM using an ammonia solution to 7.5-8.5;

4. Filtration through a filter with a mesh size of not more than 125 microns;

5. Mixing VD-LKM with a biocidal additive of silver nanoparticles at a rotational speed of the cutter of the dissolver 40-70 rpm

Compared with the prototype and the methods known in the art for producing biocidal water-dispersion paints and varnishes, in the proposed solution, the biocidal additive of silver nanoparticles is introduced under conditions ensuring its low concentration caused by the constancy of colloidal stability: low mixing speeds (40-70 rpm) final stage, pH VD-LKM 7.5-8.5. The high dispersibility of pigments and fillers ensures the subsequent more active distribution of nanoparticles throughout the volume of VD-LKM without increasing the mixing speed, prevents their coagulation and deposition on the surface of pigments due to the high negative zeta potential of pigments and fillers.

A decrease in the silver concentration in the composition of VD-LKM, when used as a biocidal additive, is achieved by reducing the size of the silver particles. To maintain the nanoscale level of silver particles, high stability conditions are created, provided by this production method.

The choice of polymer dispersion strongly affects the stability of silver nanoparticles ["Modification of aqueous polymer dispersions with silver and copper sols": dis. ... cand. tech. Sciences: 05.17.06 / Solovev Anton Valerevich. - Ivanovo, 2014 .-- 106 p.]. Acrylic polymer dispersions are one of the least affecting the stability of silver nanoparticles of aqueous polymer dispersions. Acrylic dispersions, in turn, differ in the type of emulsifier: cationic and anionic. Due to the negative zeta potential, anionic acrylic polymer dispersions more favorably affect the preservation of the dimension of silver nanoparticles and, as a consequence, its chemical and biological activity.

Maintaining a pH range of 7.5-8.5 provides the highest negative zeta potential of silver nanoparticles ["Stabilization of nanoscale silver particles for working conditions in the composition of water-dispersion paints and varnishes" / V.V. Strokova, P.S. Baskakov, K.P. Maltseva // Bulletin of BSTU named after V.G. Shukhov. - 2016. - No. 4. - S. 84-87], which gives high stability of silver nanoparticles in the environment of VD-LKM.

In the proposed method, this pH range is maintained by adjusting the composition of the VD-LKM. It is necessary to use pigments and fillers with a mass fraction of water-soluble substances of not more than 0.1% and a dispersibility of up to 10 μm and a zeta potential of less than -25 mV, which gives a high uniformity of the pigment paste and the resistance of the particles of fillers and pigments to agglomeration, which ensures the best mixing final stage at 40-70 rpm rotation of the dissolver cutter.

The resulting water-dispersion coating material must comply with GOST R 52020-2003 and GOST 33290-2015, with a pH level of 7.5-8.5, a milling degree of not more than 20 μm, which is due to the degree of dispersibility of the pigments up to 10 μm. Larger random process suspensions are removed by filtration through a 125 micron sieve.

The achievement of the biocide VD-LKM, expressed in bactericidal activity against Escherichia coli bacteria, depends on the concentration of the introduced solutions of silver nanoparticles. The method is based on the assessment of the antibacterial properties of the coating when plating a bacterial suspension on its surface, exposure and subsequent determination of the number of viable bacteria in the washed suspension. Biocidal (bactericidal) coatings based on biocidal VD-LKM is the absence of viable colony forming units of bacteria (CFU) after 24 hours exposure.

The bactericidal effect of film coatings with respect to Escherichia coli was determined in accordance with ISO 27447: 2009 (E) (Fine ceramics (advanced ceramics, advanced technical ceramics) - Test method for antibacterial activity of semi conducting photo catalytic materials)).

The study showed that the coatings obtained by the proposed method biocidal VD-LKM, ensure the complete absence of bacteria Escherichia coli after exposure for 1 day.

An example of obtaining biocidal VD-LKM.

A pigment paste is prepared on the basis of calcite, talc, rutile or their analogues, having a pH = 7.5-8.5 and not more than 0.1% water-soluble substances dispersible up to 10 μm, dispersed in an aqueous medium in a dissolver at 1500-2000 rpm min until the visible destruction of the agglomerates of pigments and fillers to prevent the excessive formation of low molecular weight electrolytes of pigments and fillers. Upon completion, the pigment paste is tested for a level of zeta potential, which should be below -25 mV. If the level of zeta potential does not match, the composition of the pigment paste should be adjusted by changing the ratio of fillers and pigments. The proportion of larger, with a lower degree of dispersibility decreases, and the content of smaller pigments and fillers increases.

Then, an anionic acrylic polymer dispersion with a high degree of stabilization, expressed in particle sizes of up to 0.1 μm, is added to the dissolver at 300-700 rpm.

Before the final stage, the pH level of the water-dispersed paint material is checked; if necessary, it is adjusted by adding an aqueous solution of ammonia. The obtained VD-LKM is filtered through a sieve with a cell of 125 μm to remove random large suspensions.

Then, at low mixing speeds (40-70 rpm), a biocidal additive of silver nanoparticles at a concentration of 1.5 μM per 1 kg of VD-LKM is introduced in small portions.

Further VD-LKM is checked for biocidality (bactericidal activity). Apply to the surface of dense glass. 0.15 ml of the bacterial suspension is applied to the obtained sample, placed in the center of the Petri dish, using a sterile pipette.

Then, after 24 hours, this sample is placed in a filter bag using sterile tweezers (Stomacher bag). Next, 10 ml of ENDO medium is added to the bag, after which it is manually wiped through a filter bag (Stomacher bag). The resulting bacterial flush solution is immediately used to determine the number of viable cells.

The test results after 1 day of exposure showed the absence of viable CFU in a coated medium based on biocidal VD-LKM obtained by the developed method.

The use of the claimed invention allows:

-Get biocidal VD-LKM with a low concentration of the introduction of a biocidal additive of silver nanoparticles;

-decrease the cost of water-dispersion coating material by reducing the concentration of the introduced biocidal additive of silver nanoparticles to 1.5 μM per 1 kg of VD-LKM.

Claims (1)

A method of producing a biocidal water-dispersion paint and varnish materials, comprising mixing a water-dispersive paint and varnish material with a biocide additive of silver nanoparticles, characterized in that the water-dispersive paint and varnish and paint material is prepared on the basis of pigment paste obtained by dispersing pigments and fillers with a mass fraction of water-soluble substances not more than 0 , 1%, dispersible up to 10 microns, zeta potential less than -25 mV and having a pH of 7.5-8.5, which is mixed with anionic acrylic polymer di with a particle size of up to 0.1 μm, then the pH level is adjusted with an ammonia solution to 7.5-8.5, and mixing with a biocidal additive of silver nanoparticles with a pH of 7.5-8.5, an average particle size of from 10 to 100 nm and using anionic or nonionic surfactants in their composition, they are carried out in a dissolver at mill rotational speeds of 40-70 rpm.