CZ32611U1 - Combined adhesive containing epoxy and geopolymer resin - Google Patents

Description

Technical field

The invention relates to a combination adhesive comprising a low molecular weight epoxy resin and a geopolymer resin based on potassium water glass and metakaolin.

BACKGROUND OF THE INVENTION

By gluing we mean a technological process which achieves a permanent joint of the same or different materials by means of an adhesive. Adhesive is a substance that connects surfaces by adhesion (adhesion) and self-cohesion (cohesion) without significantly altering the structure of the material to be bonded. The adhesion and the adhesion are applied concurrently in the bonded joint. Like other processing methods, gluing is not only characterized by many advantages, but also by some negative but also limiting factors, eg higher demands on cleanliness and accuracy of work. When deciding on the type and type of bonding, the advantages and disadvantages of gluing should be considered in comparison with traditional bonding methods. Glued joints are, unlike conventional joints made by rivets or screws, impervious to liquids, respectively. even for gases. Bonding does not affect the smoothness of the surface and therefore the aesthetic appearance of the product. Also, the mechanical properties of the construction material by drilling holes for fasteners are not impaired. Under dynamic stress on the structure, the bonded joint distributes the stresses more evenly than any other mechanical joint.

Depending on the chemical nature and application, the adhesives can be divided into two large groups. The first group consists of classical adhesives based on organic binder base for gluing various materials, the second group consists of so-called mineral adhesives for inorganic, resp. predominantly inorganic bases, which are used in the construction industry for gluing of tiles, floor tiles, thermal insulation systems, etc. A special group of mineral adhesives are refractory adhesives intended for bonding fireclay and refractory linings and insulations.

For adhesives based on organic basis, significant adhesion of macromolecular substances is used. Two terms are important when bonding with adhesive, namely cohesion and adhesion. The adhesion may be mechanical (induced by anchoring of the adhesive in the pores of the material to be bonded), electrostatic or induced by molecular attraction. The bond strength is determined by both adhesion (adhesion of the adhesive to the material to be bonded) and cohesion (cohesion between the particles of the adhesive itself). The prerequisite for bonding is always wetting of both surfaces to be joined with adhesive. According to the principle of solidification of the adhesive in the joint and according to the properties of the resulting joint, the adhesives can be divided into several types:

Adhesives cured by soaking and solvent leakage. Chemical-curing adhesives, one-component cured at temperatures of 100 to 160 ° C. Multi-component adhesives where the ingredients are mixed just before use and which solidify at normal or slightly elevated temperatures. Hot melt adhesives, which must be melted before use, usually in equipment specially designed for this purpose. Adhesives still sticky (pressure sensitive), used in the form of tapes, labels and wallpaper.

Adhesives have a great variability of utility properties and the composition design depends on their use. However, the polymeric adhesive components themselves do not meet all the requirements for material properties resulting from specific applications. The failure is often low mechanical strength of the glued joint, inappropriate rheological behavior of the adhesive or its low resistance to chemicals or elevated temperatures or fire. The rheological behavior of the adhesives is controlled by the addition of fillers and pigments, in particular of inorganic origin.

- 1 GB 32611 U1

The essence of the technical solution

The above-mentioned drawbacks are at least partially solved by an epoxy resin adhesive and a geopolymers resin. The essence of the technical solution is a combination of organic and inorganic polymer. The organic polymer (epoxy) provides high adhesion and thus high mechanical strength of the glued joint and the inorganic polymer (geopolymer) increases the fire resistance and chemical resistance to organic solvents and petroleum substances. Geopolymic resins are alkali-activated aluminosilicates. In contrast to Portland cement binders, which harden by hydration of clinker minerals, curing of the geopolymer binder takes place by polycondensation. This involves partial dissolution of aluminosilicates, transport and orientation of the dissolved ions and their subsequent polycondensation. All of these steps take place in an alkaline medium, which is a prerequisite for dissolving aluminosilicates. Alkaline hydroxides and salts catalyze said polycondensation reactions. The process for preparing geopolymer binders essentially consists in preparing a reactive mixture composed of a siliceous or aluminosilicate component with an aqueous solution of a strongly alkaline soluble silicate (water glass). The aluminosilicate component consists of alumina and silica, the most commonly used pozzolan is metakaolin. The aqueous solution of the strongly alkaline silicate contains as main constituents silica and sodium oxide or potassium oxide. Mixing the aluminosilicate component with an aqueous alkali silicate solution produces a reactive mixture, which is used as a resin for bonding and agglomerating substances of primarily mineral origin.

The combination adhesive is comprised of a synthetic, solvent-free, low molecular weight epoxy resin in an amount of 43 to 46 wt. % prepared by condensation of dianu with epichlorohydrin containing epoxy groups of 0.43 to 0.48 mol / 100 g modified with a non-reactive plasticizer, which is cured by the addition of 4 to 6 wt. % of diethylenetriamine and geopolymic resin in an amount of 43 to 46 wt. % of metakaolin and potassium waterglass containing 55% by weight dry weight and a molar ratio of S1O2 / K2O of 1.7 in a weight ratio of 7 parts metakaolin to 5 parts potassium water glass, and the rest to 100% are non-reactive pigments and fillers, such as titanium white or micronized limestone. The weight ratio of the solventless low molecular weight epoxy resin to the geopolymic resin is 1: 1 in the combination adhesive.

Examples of technical solutions

The combination adhesive containing epoxy and geopolymers is prepared as a two-component system. The first component is formed by mixing 44 wt. % solvent-free CHS-Epoxy 455 low molecular weight resin and 26 wt. of metakaolin Mefisto K05. The second component is formed by mixing 20 wt. % of potassium water glass with a molar ratio of S1O2 / K2O of 1.7 and a dry matter of 55% with 5% diethylenetriamine and 5% by weight a 1: 1 mixture of titanium dioxide and micronized limestone. Just before use, the two components are mixed, the density of the adhesive formed is 1.4 g / cm ³ and the dry matter is 91%.

Industrial applicability

The combination adhesive containing the epoxy and geopolymers resin according to the invention is industrially applicable for bonding various materials in which the adhesive bonds are thermally and chemically stressed.

Claims (1)

Combination adhesive based on epoxy and geopolymic resin, characterized in that it comprises a solvent-free low-molecular-weight epoxy resin in a total amount of 43 to 46% by weight containing from 0.43 to 0.48 mol / 100 g of epoxy groups cured by the addition of 4 to 6 % wt. diethylenetriamine; % and further from 43 to 46 wt. geopolymic resins consisting of metakaolin and potassium waterglass containing 55 wt. dry matter and molar ratio S1O2 / K2O 1.7 in a weight ratio of 7 parts metakaolin to 5 parts potassium water glass; and the remainder to 100 wt. it consists of non-reactive pigments and fillers.