EP3086892A1

EP3086892A1 - Two-component system, in particular for forming an adhesive

Info

Publication number: EP3086892A1
Application number: EP14821176.6A
Authority: EP
Inventors: Christian Fourberg; Ditmar Baier
Original assignee: Huettenes Albertus Chemische Werke GmbH
Current assignee: Huettenes Albertus Chemische Werke GmbH
Priority date: 2013-12-23
Filing date: 2014-12-19
Publication date: 2016-11-02
Also published as: CN105848804A; KR20160102000A; WO2015097108A1; US10106462B2; JP2017508824A; MX2016008350A; US20160311724A1; JP6474819B2

Abstract

The invention relates to a two-component system, in particular for forming an adhesive which is suitable, for example, for applications in the foundry industry and the construction industry.

Description

Two-component system, in particular for the formation of an adhesive

The present application relates to a two-component system, in particular for the formation of an adhesive which is suitable, for example, for applications in the foundry industry and / or in the construction industry.

In the foundry industry, adhesive bonds between parts of foundry molds are currently often used with organic hot melt adhesives or polyurethane adhesives (in the form of two component systems) or thermosetting inorganic waterglass adhesives.

Hot melt adhesives whose adhesive effect is caused by solidification of a melt must be melted before their use. This means a relatively high expenditure in terms of equipment and time.

Organic adhesives are detrimental in the foundry industry because they release volatile organic compounds (VOC) at the high temperatures to which molds or cores are exposed, thereby causing defects (gas bubbles) in the finished casting. In order to reduce the emission of volatile organic compounds (VOC) in foundries, molding materials and cores are increasingly being used with inorganic binders. In this context, it is also strives to use adhesives which do not or only to a small extent cause emissions of volatile organic compounds. In addition, the compatibility of materials between organic adhesives and molded materials bonded by an inorganic binder is often not very high, which affects the reliability of the adhesive bonds.

The problems caused by the use of organic adhesives can be avoided if they are replaced by inorganic adhesives such as thermosetting water glass adhesives. However, for thermosetting (setting) of water glass based adhesives, the removal of water, i. drying at elevated temperature, required, e.g. in an oven or a microwave oven. This means a relatively high expenditure in terms of equipment and time. In addition, there is a risk of incomplete hardening of the water glass, so that the resulting adhesive bonds are sensitive to changes in humidity.

In addition to the thermal hardening of water glass by dehydration, the chemical hardening of water glass by means of carbon dioxide or by means of esters is known as a hardener.

EP 0 641 748 A1 discloses a composition for fixing dowels, threaded rods and the like in cavities, in particular boreholes, in concrete, stone and brickwork, based on waterglass with at least one fine-grained, highly active reaction partner such as Si0 ₂ and / or Al ₂ 0 ₃ and with fillers, such as quartz powder and / or quartz sand, wherein the water glass has a molar ratio of Si0 ₂ to alkali oxide of> 1, 4, preferably 1, 45 to 1, 60, but <2, and the mass also to 100 Parts by weight of water glass based 10 to 40 parts by weight of a curing agent which neutralizes the elimination of an acid with respect to the silica acid of the alkali of the water glass. In the process for producing such a mass, the water glass (optionally together with a condenser) is presented, the highly active reactants (such as Si0 ₂ and / or Al ₂ 0 ₃ ) added with stirring, then, also with stirring, the fillers added and then, at a high stirring speed, the hardener is added. The masses thus produced have pot lives of 25 minutes to one hour and reach their final strength after 30 hours or more.

The object of the present invention is, in particular for foundry applications, means and methods for producing fast-curing, reliable adhesives. Provide connections. The curing process should preferably take place without supply of thermal energy, and preferably not be influenced to a relevant extent by the temperature of the objects to be joined.

The agents and methods according to the invention should not require a high technical effort in their handling. The proportion of organic substances to be used for the production of the adhesive bonds should be low.

This object is achieved by a two-component system, in particular for the formation of an adhesive, comprising or consisting of

a component (A) comprising the constituents

(A-i) an alkali metal silicate or a mixture of two or more than two alkali metal silicates, wherein in the one or more alkali metal silicates the molar ratio of silica to alkali metal oxide ranges from 2 to 5, and

(A-ii) water

and

- a component (B) comprising the constituent

(B-i) a compound selected from the group consisting of cyclic esters of carbonic acid, γ-butyrolactone and carboxylic acid esters of polyhydric alcohols or a mixture of two or more than two of these compounds

the ratio

the total mass of all alkali metal silicates (A-i) of component (A)

to

the total mass of component (B-i) of component (B)

is in the range of 2: 1 to 8: 1, preferably in the range of 3: 1 to 5: 1,

wherein in the two-component system, the components (A) and (B) are arranged so that no constituent of the component (A) can react with a constituent of the component (B).

Within the two-component system according to the invention, the reactive contact of constituents of component (A) with constituents of component (B) is precluded, for example by virtue of component (A) on the one hand and component (B) on the other hand each provided in a separate container, or by the component (A) on the one hand and the component (B) on the other hand in each case in a separate chamber of a container (eg a two-chamber cartridge) are provided.

In the two-component system according to the invention, component (A) and component (B) are preferably present as paste or as gel. The water content of component (A) is therefore preferably selected so that the alkali metal silicates (as defined above) contained in component (A) are not completely dissolved. Typically, the water content of component (A) is 60% by weight or less, typically 30% to 50% by weight of the total mass of component (A), more preferably 35% to 45% by weight. , in each case based on the total mass of component (A).

Component (B-i) of component B is intended to act as a hardener for the alkali metal silicates contained in component (A) as component (A-i). The curing of alkali metal silicates (water glass) by esters is known from the technical field of binders for foundry molding materials (water glass ester method). The function of the component (B-i) can be described regularly as that of an activator for the curing of the water glass. The hardening of water glass leads to the formation of polysilicic acids which have a high strength.

Since the ester or the products formed in the ester cleavage itself are not part of the curing product, based on component (A-i) already satisfy relatively small amounts of the component (B-i) to cause the curing of the water glass. Thus, as desired in particular for foundry applications, the proportion of organic constituents in the two-component system according to the invention can be kept low. Inventive two-component systems with a low proportion of organic compounds are also suitable for applications with high requirements in terms of fire protection.

In the alkali metal silicates to be used as component (Ai) according to the invention, the molar ratio of silica to alkali metal oxide is preferably in the range from 2 to 5, particularly preferably 2.5 to 3.8. The two-component system according to the invention is particularly suitable for producing an adhesive by mixing the components (A) and (B) of the two-component system according to the invention in a static mixing device. Static mixing devices are apparatus for the continuous mixing of substances comprising a tube provided with suitable immovable internals. The mix is transported by impressing a pressure difference through the pipe. The internals arranged in the tube are designed such that they effect a repeated division and merging of the mixed material flow and / or the formation of turbulences, whereby concentration differences or inhomogeneities within the mixed material flow are minimized. Suitable forms of the internals for static mixing devices are known in the art. For example, the internals can be designed so that the flow of mixed material must pass through a labyrinth-like area.

Static mixing devices typically have lower investment, operating and maintenance costs compared to dynamic mixing devices because they have a smaller number of moving equipment components.

By means of a static mixing device, an intimate homogeneous mixing of the components (A) and (B) can be achieved and, in turn, a uniform hardening of the mixture formed and a reliable, load-bearing adhesive bond. The component (A) preferably has a dynamic viscosity in the range from 1 Pa.s to 70 Pa.s, determined according to DIN 53019-01 with a rotational viscometer VT 550 from Haake with a rotary spindle 100 at a temperature of 20 ° C. The components - Te (B) at a temperature of 20 ° C preferably has a dynamic viscosity in the range of 0, 1 Pa * s to 20 Pa * s, preferably 1 Pa * s to 20 Pa * s, determined DIN 53019-01 with a Haake's VT 550 rotary viscometer with SV1 spindle and Haake SV measuring cup.

For pasty materials, the sample is heated to 20 ° C during sample preparation. Subsequently, the immersion of the measuring spindle takes place up to the dipping mark. In the low-voltage state of the measuring arrangement, the torque load cell is set to zero. Subsequently, the measurement is carried out until the constancy of the measured value at a given speed. In this case, a thixotropic material behavior is to be considered.

The upper limits of the dynamic viscosities of component (A) and component (B) are determined, in particular, by the fact that highly viscous substances are difficult to handle and are difficult to mix with one another. The lower limits of the dynamic viscosities of component (A) and component (B) are in particular determined by the fact that the adhesive when applying to a splice should not flow uncontrolled beyond the boundaries of the splice.

Preference is given to two-component systems according to the invention in which the ratio of the viscosity of component (A) to the viscosity of component (B) is in the range from 1: 4 to 30: 1. By means of this preferred embodiment, it is possible to achieve a particularly intimate homogeneous mixing of the two components and, in turn, a uniform hardening of the mixture formed and a reliable, load-bearing adhesive bond.

Neither for the component (A) nor for the component (B) of the two-component system according to the invention is the presence of further constituents in addition to the above-defined constituents (A-i), (A-ii) or (B-i) excluded.

The component (A) may be formed by, for example, a conventional thermosetting waterglass adhesive.

In a preferred embodiment, component (B) of the two-component system according to the invention comprises as further constituents

(B-ii) amorphous silica

wherein the amorphous silica is preferably selected from the group consisting of fumed silicas, precipitated silicas, silica fume condensate and mixtures thereof

and or

(B-iii) one or more zeolites.

The component (B) of the two-component system according to the invention particularly preferably comprises as further constituents

(B-ii) amorphous silica, wherein the amorphous silica is preferably selected from the group consisting of fumed silicas, precipitated silicas, silica fume condensate and mixtures thereof, wherein the mass fraction of component (B-ii) is preferably 20% by weight or less is, based on the total mass of component (B),

and or (B-iii) one or more zeolites, wherein the mass fraction of the component (B-iii) is preferably 40% by weight or less, based on the total mass of the component (B).

When component (B) contains component (B-ii), the proportion by mass of component (B-ii) as defined above is preferably 20% by weight or less, based on the total mass of component (B). The mass fraction of constituent (B-ii) is preferably 2% by weight to 20% by weight, particularly preferably 5% by weight to 15% by weight, based in each case on the total mass of component (B),

When component (B) contains component (B-iii), the proportion by mass of component (B-iii) as defined above is preferably 40% by weight or less based on the total weight of component (B). The mass fraction of constituent (B-iii) is preferably from 10% by weight to 25% by weight, particularly preferably from 10% by weight to 15% by weight, based in each case on the total mass of component (B).

Component (B) contains component (B-ii) and component (B-iii). thus, the content by mass of the component (B-ii) as defined above is preferably 20% by weight or less, and the content by mass of the component (B-iii) as defined above is preferably 40% by weight or less, based on the total mass of the component Component (B). The mass fraction of components (B-ii) and (B-iii) taken together is thus preferably at most 60 wt .-%, based on the total mass of component (B). It is preferred that the mass fraction of the component (B-ii) 2 wt .-% to 20 wt .-%, particularly preferably 5 wt .-% to 15 wt .-%, each based on the total mass of the component (B ), and the mass fraction of constituent (B-iii) is from 10% by weight to 25% by weight, particularly preferably from 10% by weight to 15% by weight, based in each case on the total mass of component (B) ,

Silicic acid is a collective term for compounds of general formula (Si0 ₂₎ _m ^■ nH ₂ 0 according to DIN 55943: 2001-10 is a silica produced by wet chemical, thermal or pyrogenic processes silica, which is characterized by x-ray or electron diffraction as amorphous.

Precipitated silicas (CAS No. 1 12926-00-8) are a finely divided amorphous form of silica prepared by precipitation from aqueous alkali metal silicate solution (waterglass) with mineral acids, eg, sulfuric acid, or with carbon dioxide. Pyrogenic silicas (also called fumed silica, CAS No. 1 12945-52-5) are a finely divided amorphous form of silica prepared by flame hydrolysis of silicon tetrachloride.

Another finely dispersed amorphous form of silica is the silica fume condensate obtainable by reduction of quartz with carbon in the arc furnace. Such a product, which is produced as a by-product in the production of silicon and ferrosilicon by reduction of quartz with a carbonaceous material, is also designated by the trade name "microsilica" or "silica fume" (CAS No. 69012-64-2 ).

Amorphous silica for use as component (B-ii) preferably consists of particles having a primary particle size in the range of 5 nm to 1 μm. The function of the optional ingredient (B-ii) amorphous silica is i.a. in that the viscosity and / or thixotropy of component (B) to influence and the material compatibility of the organic component (Bi) containing component (B) with the predominantly or exclusively composed of inorganic substances component (A) to improve and thus the mutual wetting and mixing the components (A) and (B). In addition, the component (B-ii) in the mixture formed by mixing the components (A) and (B) increases the molar ratio of silica to alkali metal oxide (see above) compared to the molar ratio of silica to alkali metal oxide in component (Ai), and thus accelerates the hardening. The amorphous silica of component (B-ii) participates in the curing of the water glass and is incorporated into the resulting polysilicic acids. The mechanical properties of the cured material, its shrinkage and adhesion to surfaces (e.g., when applied as an adhesive to the surfaces of the articles to be joined) are significantly improved by the addition of the amorphous silica.

Since the above-described interactions between the component (B-ii) of the component (B) on the one hand and the component (A), in particular its component (Ai), on the other hand, should occur only when both components are mixed together to form an adhesive , in the two-component system according to the invention, the amorphous silica (B-ii) is separated from the components of component (A).

Since the abovementioned amorphous forms of the silica are very finely divided and thus comparatively difficult to handle, it is advantageous to use the amorphous silicon dioxide as component (B-ii) of the component (B) of the two-component system, and not as a separate component. By combining with the component (Bi), the amorphous silica is incorporated into the component (B), which thus preferably obtains an gel-like paste-like consistency. Zeolites (Component (B-iii) are crystalline aluminosilicates of the general formula

M _{2 / z} O ^■ Al ₂ 0 ₃ ^■ ^■ xSi0 ₂ yH ₂ 0,

wherein M is a cation selected from the group consisting of metal cations (usually alkali or alkaline earth cations), H ⁺ and NH ₄ ⁺ , z is the valency of the cation, x = 1, 8 to 12 and y = 0 to 8. Zeolites are characterized by a framework and pore structure, which among other things allows the absorption of water. The crystal lattices of the zeolites are composed of Si0 ₄ and Al0 ₄ tetrahedra, which are each linked to one another via oxygen bridges and form rings or prisms. These in turn combine with other secondary building blocks, each containing up to 16 Si or Al atoms. The result is a spatial arrangement of identical cavities, which are accessible via windows (pore openings) or three-dimensional duct systems. In the crystal lattice of zeolites there are only SiOAl and / or SiOSi bridges, but no AIOAI bridges. Therefore, in zeolites, the modulus Si / Al is equal to or greater than 1.

Preference is given to using zeolites of the zeolite A type having a pore size of 3 angstroms (300 pm = 300 * 10 ^-12 m), 4 angstroms (= 400 pm) or 5 angstroms (500 pm), more preferably 3 angstroms synthetic, colorless, crystalline aluminosilicate and has in its hydrated sodium form the empirical formula Na ₁₂ ((AlO 2) i 2 (SiO ₂ ) i 2) ^■ 27H ₂ 0.

Other suitable zeolites are listed in the following table:

Zeolite X Na ₈₆ [(AIO ₂ ) 86 (SiO ₂ ) _{1 0} 6] ^■ 264 H ₂ 0

Zeolite Y Na ₅ 6 [(Al0 ₂ ) 56 (Si0 ₂ ) _{1 3} 6] ^■ 250 H ₂ 0

Zeolite LK ₉ [(AlO ₂ ) ₉ (SiO ₂ ) ₂₇ ] ^■ 22 H ₂ 0

Mordenite Na ₈ , ₇ [(Al0 ₂ ) ₈ , 7 (Si0 ₂ ) ₃ 9.3] ^■ 24 H ₂ 0

It has been found that the addition of zeolites (B-iii) to component (B) of the two-component system according to the invention improves the long-term stability of adhesive bonds produced according to the invention. It is currently believed that this is due to absorption of component (A) water (A-ii) by the zeolite (B-iii). The release of water after preparation of the adhesive bond is a process that extends over several days and limits the life of the adhesive bond, unless appropriate countermeasures are taken. The use of one or more zeolites as component (B-iii) prolongs the life of the adhesive bond (in particularly preferred embodiments, up to four weeks or longer) because the absorbent action of the zeolites (B-iii) slows the release of water. For applications in which no long life of the adhesive bond is required, but also inventive two-component systems without component (B-iii) are suitable.

In a further embodiment, component (B) contains a two-component system according to the invention

(B-iv) Fly ash, preferably fly ash of hard coal combustion, prefers fly ash from hard coal-fired power plants

and optionally components (B-ii) and / or (B-iii) as described above.

The proportion of the component (Ai) of the component (A) to the component (B-ii) of the component (B) of the preferred two-component system of the present invention determines the ratio of silica to alkali metal oxide in the component (A) and (B ) and thus has a significant influence on the curing rate of the mixture and the proportion of binding polysilicic acids in the cured adhesive. Preference is given to a two-component system according to the invention, wherein the ratio

the total mass of all alkali metal silicates (A-i) of component A.

to

the total mass of component (B-ii) of component B in the range from 10: 1 to 70: 1, preferably in the range from 20: 1 to 50: 1, particularly preferably in the range from 30: 1 to 40: 1.

The ratio is preferably in the component (B) of the two-component system according to the invention

the total mass of the component (B-i)

to

the total mass of amorphous silica (B-ii)

in the range of 2: 1 to 20: 1, preferably 3: 1 to 20: 1, preferably in the range of 5: 1 to 10: 1.

The compounds of component (Bi) of component (B) of the two-component system according to the invention are esters which are capable of curing on mixing the component (A) with component (B) according to the method of the binders for Foundry molding materials to effect known water glass ester method.

Preferably used as or in component (B-i) of component (B) of the two-component system according to the invention are cyclic esters of carbonic acid of the formula (I)

wherein in the formula (I) R- ₁ and R _{2 are} each independently selected from the group consisting of hydrogen, unbranched alkyl groups having 1 to 6 carbon atoms and branched alkyl groups having 4 to 6 carbon atoms. Particularly preferred are the cyclic carbonic acid esters from the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate. Another group of compounds which are preferably used as or in component (Bi) of component (B) of the two-component system according to the invention are carboxylic acid esters of polyhydric alcohols. Polyhydric alcohols are alcohols having two or more hydroxy groups per molecule. In the esters to be used according to the invention, one, several or all hydroxyl groups of the polyhydric alcohol are esterified by carboxylic acids. Preferred are carboxylic acid esters of polyhydric alcohols from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol and glycerol.

Among the carboxylic acid esters of polyhydric alcohols from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, mono- and di-acetic acid esters are preferred according to the invention.

Preferred carboxylic acid esters of glycerol according to the invention are compounds of the formula (II)

(II)

wherein in the formula (II) R ₃ , R ₄ and R _{5 are} each independently selected from the group consisting of hydrogen and acyl groups -C (O) R ₆ , wherein R ₆ in the acyl groups is independently selected from the group consisting of straight chain alkyl groups of 1 to 6 carbon atoms and branched chain alkyl groups of 4 to 6 carbon atoms, provided that at least one of R ₃ , R ₄ and R _{5 is} an acyl group as defined herein. Particularly preferred are mono-, di- and tri-acetic acid esters of glycerol. The diacetic acid ester of glycerol is also referred to as diacetin. The tri-acetic acid ester of glycerol is also referred to as triacetin.

The component (Bi) of component (B) of the two-component system according to the invention is particularly preferably formed from a mixture consisting of one or more compounds of the formula (I), for example propylene carbonate, and one or more compounds of the formula (II), for example the acetic triester of Glycerols (triacetin). In component (A) of the two-component system according to the invention, one, several or all of the alkali metal silicates (Ai) present are preferably selected from the group consisting of sodium silicate, potassium silicate and mixtures thereof.

In a preferred embodiment, component (A) of the two-component system according to the invention comprises as further constituent

(A-iii) one or more fillers selected from the group consisting of aluminosilicates, crystalline forms of silica, magnesia, calcia, chromia, zirconia, alumina, zirconium silicate, chromite, magnesite, and mixtures thereof.

Ingredient (A-iii) does not contain alkali metal silicates having a molar ratio of silica to alkali metal oxide in the range of 2 to 5 (these are included in component (A-i)) and no amorphous forms of silica (component B-ii). The fillers of ingredient (A-iii) are preferably used in the form of naturally occurring minerals. Among the crystalline forms of silica, quartz (especially in the form of quartz sand or quartz powder) is preferred. Among the aluminosilicates, hydrated aluminosilicates, especially clay minerals and clays, in particular kaolins and bentonites (containing as the main constituent the mineral montmorillonite), are preferred. Another preferred tone is Kärlicher blue tone. For foundry applications, the filler or at least one of the fillers is preferably selected so as to be identical or at least similar to the molding material contained in the parts to be joined of a foundry mold. Ingredient (A-iii) contains no zeolites.

Corresponding fillers are also used in conventional thermosetting water-glass adhesives and are thus known to the person skilled in the art. Fillers are materials which undergo little or no volume shrinkage when a mixture formed from the two-component system according to the invention is cured. The function of the filler is to adjust the desired dynamic viscosity of component (A), and to achieve a desired degree of filling in the adhesive formed from the two-component system according to the invention.

Preference is given to fillers (A-iii) which are capable of binding or storing water by swelling or in some other way. This applies, for example, to the above-mentioned clays and clay minerals. It has been shown that the addition of water-binding fillers (A-iii) to component (A) of the two-component system according to the invention improves the long-term stability of adhesive bonds produced according to the invention. It will presently believed to be due to binding of component (A) water (A-ii) by the water-binding filler (A-iii). The release of water after preparation of the adhesive bond is a process that extends over several days and limits the life of the adhesive bond, unless appropriate countermeasures are taken. The use of one or more water-binding fillers (A-iii) prolongs the service life of the adhesive bond, as the water-binding action of the fillers (A-iii) slows down the release of water. For applications in which no long service life of the adhesive bond is required, but also two-component systems without water-binding fillers (A-iii) are suitable.

The ratio is preferably in the component (A) of the two-component system according to the invention

(A-i) of the total mass of all alkali metal silicates

to

(A-iii) the total mass of said fillers

in the range of 1: 1 to 1: 2, preferably 1: 1, 4 to 1: 1, 7.

In order to reduce the use of organic materials for applications in the foundry industry for the reasons described above, it is preferable that the total content of the components (A) and (B) of the two-component organic carbon system of the present invention is 6% by weight or less , preferably 5.5 wt .-% or less, more preferably 4 wt .-% or less, based on the total mass of the components (A) and (B). The carbon content is determined by means of an elemental analysis (combustion analysis), preferably by means of the Vario Max CNS system from Elementar. In a preferred embodiment, the component (A) of a two-component system according to the invention contains as further constituents

(A-iv) one or more surfactants and / or

(A-V) one or more mineral oils.

The sum of the mass fractions of constituents (A-iv) as defined above and (Av) as defined above is preferably 2% by weight or less, based on the total mass of component (A). The addition of surfactants (also commonly referred to as "wetting agents" or "wetting agents") can be used to improve the wetting and adhesion behavior on the surfaces of the objects to be joined, inter alia when using a two-component system according to the invention as an adhesive. Suitable anionic see surfactants, especially those with a sulfate, sulfonate or a phosphate group. The anion of the anionic surfactant is preferably selected from the group consisting of oleylsulfate, stearylsulfate, palmitylsulfate, myristylsulfate, laurylsulfate, decylsulfate, octylsulfate, 2-ethylhexylsulfate, 2-ethyloctylsulfate, 2-ethyldecylsulfate, palmitoleylsulfate, linolylsulfate, laurylsulfonate, 2-ethyldecylsulfonate, palmitylsulfonate , Stearyl sulfonate, 2-ethyl stearyl sulfonate, linolyl sulfonate, hexyl phosphate, 2-ethylhexyl phosphate, capryl phosphate, lauryl phosphate, myristyl phosphate, palmityl phosphate, palmitoleyl phosphate, oleyl phosphate, stearyl phosphate, poly (1, 2-ethanediyl) phenol hydroxyphosphate, poly (1, 2 ethanediyl) stearyl phosphate and poly (1, 2-ethanediyl) oleyl phosphate. Particularly suitable surfactants are sodium ethylhexyl sulfate and sodium octyl sulfate. The surfactants (A-iv) are used as pure substances or in the form of aqueous solutions having a surfactant content of 10% by weight or more, based on the weight of the aqueous solution. However, only the masses of the surfactants themselves count for the calculation of the mass fraction of the surfactants (A-iv) on component (A). If surfactants (A-iv) are used in the form of aqueous solutions, their water content is that of constituent (A-ii ).

The term "mineral oil" is a collective term for liquid distillation products derived from mineral resources (petroleum, lignite, coal, wood, peat) .The main constituent of mineral oils are mixtures of saturated chain hydrocarbons (paraffins), aromatic hydrocarbons and alicyclic hydrocarbons (naphthenic hydrocarbons) The addition of mineral oil (Av) enhances the wettability of component (A) and extends the time until component (A) forms a skin by reaction of the alkali metal silicates (Ai) with CO ₂ contained in the ambient air is troublesome and undesirable in the production of adhesive bonds, as it hinders the adhesion of the adhesive to the surfaces of the articles to be joined The phenomenon of skin formation is known from water-glass adhesives It is currently believed that the addition of mineral oil is a passivation of the alkali metal silicates (Ai) with respect to the reaction with C0 ₂ causes. In particular, for use in the foundry industry, a two-component system according to the invention is preferred whose components (A) and (B) are coordinated with respect to their composition and their mass ratio so that the mixture formed by mixing the components (A) and (B) has a pot life in the range of one minute to 1 hour, preferably 2 minutes to 1 hour, more preferably in the range of 3 minutes to 30 minutes.

Pot life, also referred to as processing time, is the period during which a multi-component adhesive can be used after its ingredients have been mixed. For the two-component systems of the present invention, the pot life is determined by method 4.3 of DIN EN 014022. The pot life is determined by the curing rate, which depends on the composition of components (A) and (B) as described above, in particular with regard to the components (Ai) and (if present) (B-ii). Thus, by suitable choice of the composition of the components (A) and (B), the pot life can be varied, and depending on the desired application, two-component systems according to the invention can be provided with the appropriate pot life. While pot lives of less than 30 minutes are particularly suitable for foundry applications, longer pot lives are acceptable for applications in the construction industry.

Preferably, the mixture formed by mixing the components (A) and (B) of the two-component system according to the invention is an adhesive.

The mixing of components (A) and (B) of the two-component system according to the invention is preferably carried out in a static mixing device (as described above).

Particularly preferred according to the invention are two-component systems which combine two, several or all of the features described above as being preferred.

Another aspect of the present invention relates to a kit for producing an adhesive comprising

a two-component system according to the invention, preferably in one of the preferred embodiments described above

a static mixing device for mixing the components (A) and (B) of this two-component system. The static mixing device is preferably part of a device for applying an adhesive to a splice, for example an adhesive device of the type typically used for the application of organic two-component adhesives such as polyurethane or epoxy two-component adhesives. Corresponding devices are known in the art and typically include a two-chamber cartridge and a static mixing device in the form of a mixing tube.

Another aspect of the present invention relates to the use of a two-component system according to the invention or a kit according to the invention for producing an adhesive bond between objects to be joined.

To produce an adhesive bond, the adhesive produced according to the invention is applied to one or more splices. In this case, an adhesive point is understood to be a coherent area to be acted upon by the adhesive on a surface of one of the objects to be joined. In this case, the adhesive is spot-shaped on a splice, for example, e.g. in the form of a dot with a diameter of 2 mm or smaller, preferably 1, 5 mm or smaller, applied, or in the form of a bead, typically in the form of a bead having a diameter of 3 mm or less, preferably 2 mm or less. In this case, the viscosity of the adhesive should be chosen so that it can - if desired - be applied to splices of low expansion, without going beyond the limit of the splice. The use of a two-component system according to the invention is not limited to splices with the dimensions exemplified here.

Preference is given to the use of a kit according to the invention for producing an adhesive bond, wherein the objects to be joined by the adhesive bond at the splices contain one or more inorganic materials selected from the group of ceramic materials, in particular from the group consisting of oxides and silicates.

The objects to be joined by the adhesive bond are particularly preferably parts of a foundry mold, wherein the parts to be joined of a foundry mold preferably each contain mold primers bound by a binder formed by curing (preferably thermal curing) one or more alkali metal silicates. By dividing a foundry mold here are understood forms (which define the outer contours of the casting to be produced), cores (which define the inner contours of the casting to be produced) and feeders, as well as parts of such shapes, cores and feeders. In this case, for example, by connecting elements of a core according to the invention, a core is formed, by connecting parts of a mold according to the invention to a mold and by connecting parts of a feeder according to the invention to a feeder.

The production of foundry molds using water glass as a binder is known in the art. As mold bases for the production of molds commonly used materials are used such as quartz or zircon sand, chamotte, mullite, olivine, chrome ore, vermiculite or other refractory mold base materials. According to the standard DIN 51060 "Refractory ceramic raw materials and refractory products" materials are referred to as refractory with resistance to temperatures of> 1500 ° C and as highly refractory with resistance to temperatures of> 1800 ° C.

A particularly preferred field of application of two-component systems according to the invention is the production of adhesive bonds between parts of a feeder, and in particular between a feeder insert and a breaker core (preferably a croning breaker core). Another particularly preferred field of application of two-component systems according to the invention is the production of adhesive bonds between parts of Gießanschnitt- and / or running structures. Such structures are typically composed of two or more parts, usually in the form of tubular sections, preferably made of highly refractory ceramic material, wherein the individual parts are joined together by adhesive bonding.

Another particularly preferred field of application of two-component systems according to the invention is the production of adhesive bonds between cores or parts of cores.

A further aspect of the present invention relates to the use of a static mixing device for producing an adhesive, wherein the adhesive is prepared by mixing the components (A) and (B) of a two-component Systems (preferably in one of the preferred embodiments described above) is made in the static mixer.

Another aspect of the present invention relates to a method of making an adhesive comprising the step

- Mixing of components (A) and (B) of a two-component system according to the invention (preferably in one of the preferred embodiments described above).

In the method according to the invention for producing an adhesive, the mixing of components (A) and (B) of a two-component system according to the invention (preferably in one of the preferred embodiments described above) is preferably carried out in a static mixing device.

A further aspect of the present invention relates to a method for producing an adhesive bond between articles to be joined, comprising the steps:

Preparation of an adhesive according to the above-described method according to the invention (preferably according to one of the above-described preferred variants of the method according to the invention for producing an adhesive)

Applying the adhesive to one or more splices to form an adhesive bond between the articles to be joined

- Allow the adhesive to cure.

Preference is given to a method according to the invention for producing an adhesive bond between objects to be joined, wherein the adhesive produced according to the invention

has a pot life in the range of 2 minutes to 1 hour, preferably in the range of 3 minutes to 30 minutes.

With regard to the influence of the composition and amount of the components (A) and (B) of the inventive two-component system on the pot life of a mixture formed by mixing the components (A) and (B), the above statements apply. With regard to the articles to be joined by means of the method according to the invention for producing an adhesive bond (in particular in its preferred embodiments), the above statements apply.

The two-component system according to the invention, the kit according to the invention and the method according to the invention are suitable, for example, for applications in the foundry industry and in the construction industry.

The curing process of an adhesive formed according to the invention by mixing the components (A) and (B) of a two-component system according to the invention is not significantly influenced by the temperature of the articles to be joined. This is an advantage for use in joining parts of a foundry mold since foundry molded parts bonded with a thermoset binder (e.g., waterglass) often still have some residual temperature after curing (typically in the range of 40 to 80 ° C).

Adhesive compounds prepared by the process of the invention are characterized by high tensile strength and low sensitivity to changes in the humidity of the surrounding air. Adhesive bonds prepared by the process according to the invention, in particular using the particularly preferred embodiments of the two-component system according to the invention described above, are also less susceptible to contact with water, e.g. when treating according to the invention by an adhesive bond connected parts of a foundry mold with an aqueous size. In addition, adhesive bonds produced by the process according to the invention have a high stability to thermal loads.

The present invention will be explained below with reference to exemplary embodiments.

Inventive two-component systems (Nos. 1 to 13) having the compositions indicated in the following Table 1 were prepared.

The respective components (A) and (B) of the two-component systems 1 to 13 were mixed in a static mixer. For systems 1 to 7, a two-chamber cartridge with the A: B volume ratio of 10: 1 with mounted static mixing tube was used. 66 g of component A were filled into the first chamber bubble-free. In the second chamber 5 g of component B were also filled bubble-free. The cartridge was tempered at 20 ° C. Subsequently, 30 g of sample material were pressed out with a corresponding punch from the mixing tube of the cartridge after discarding a minimum flow.

For systems 8 to 13, a two-chamber cartridge with the A: B volume ratio of 10: 1 with mounted static mixing tube was used. 72 g of component A were filled into the first chamber without bubbles. In the second chamber 5 g of component B were also filled bubble-free. The cartridge was tempered at 20 ° C. In systems 8 to 13, a mixture consisting of kaolin and quartz powder is used as constituent (A-iii), in which the weight ratio of kaolin to quartz powder is 2: 1.

The pot lives of the mixtures were determined according to the standard DIN EN 014022, method no. 4.3. The results are given in the following table.

Depending on the composition of the components (A) and (B), two-component systems according to the invention having different pot lives can be produced. While two-component systems according to the invention having pot lives of less than 30 minutes are particularly suitable for use in joining parts of a foundry mold, the two-component systems according to the invention with longer pot lives are particularly suitable for applications in the construction industry.

Table 1

System Topf¬

Component (A) Component (B)

No time

(A-i) (A-ii) (A-iu) (A-iv) (A-v) (B-i) (B-u) (B-iii)

Alkali metal water kaolin surfactant mineral oil triacetin propylene pyrogenic zeolite silicate carbonate silicic acid

(Wt% (wt% (wt% (wt% (wt% (wt% (wt% (wt% (wt% [min] based on based on based on based on based on based on

TotalTotalAllTotalTotal of mass of mass of mass of mass of mass of mass of mass of mass of

(A) (A) (A) (A) (A) (B-i) (B-i) (B) (B)

1 24 36 40 0 0 0 100 9 0 4,5

2 24 36 40 0 0 35 65 9 0 6,5

3 24 36 40 0 0 65 35 9 0 1 1

4 24 36 40 0 0 80 20 9 0 24

5 24 36 40 0 0 90 10 9 0 60

7 23,76 36, 14 39,6 0,5 0 78 22 3,9 9,3 9

8 23,64 35,46 39,4 0,5 1, 0 78 22 3,9 9,3 9

System Topf¬

Component (A) Component (B)

No time

(A-i): (A-iv): (A-v): (B-i) (B-u) (B-iii) Alkali metal Water Kaolin / surfactant Mineral oil Triacetin Propylene pyrogenic zeolite

silicate quartz flour carbonate silicic acid

Weighted ratio 2: 1

(% By weight (wt% (wt% (wt% (wt% (wt% (wt% (wt% [min] based on (wt. % based on based on referred to

TotalTotalsTotalTotalTotalTotalTotal of mass of total mass mass of mass of mass of mass of mass of mass of

(A) (A) of (A) (A) (A) (B-i) (B-i) (B) (B)

8 23 44 33 0 0 35 65 9 0 1

9 23 44 33 0 0 65 35 9 0 3

10 23 44 33 0 0 90 10 9 0 1 1

1 1 23 44 33 0 0 100 0 5 0 35

12 22,8 44, 1 32,7 0,4 0 92 8 5 10 5

13 22,7 43,3 32,5 0,5 1 92 8 5 10 5

Claims

claims

1. Two-component system comprising or consisting of

a component (A) comprising the constituents

(A-i) an alkali metal silicate or a mixture of two or more than two alkali metal silicates, wherein in the one or more alkali metal silicates, the molar ratio of silica to alkali metal oxide ranges from 2 to 5, and

(A-ii) water

and

a component (B) comprising the constituent

the ratio

the total mass of all alkali metal silicates (A-i) of component (A) to

the total mass of component (B-i) of component (B) is in the range from 2: 1 to 8: 1, preferably in the range from 3: 1 to 5: 1,

2. The two-component system according to claim 1, wherein component (B) comprises as further constituents:

(B-ii) amorphous silica, wherein the amorphous silica is preferably selected from the group consisting of fumed silicas, precipitated silicas, silica fume condensate and mixtures thereof, wherein the mass fraction of component (B-ii) is preferably 20% by weight or less is based on the total mass of component (B), and / or (B-iii) one or more zeolites, wherein the mass fraction of the component (B-iii) is preferably 40% by weight or less, based on the total mass of the component (B).

The two-component system according to claim 2, wherein in the component (B) the ratio

the total mass of the component (B-i)

to

the total mass of amorphous silica (B-ii)

is in the range of 2: 1 to 20: 1, preferably 5: 1 to 10: 1.

Two-component system according to one of the preceding claims, wherein in component (B)

one, several or all compounds of component (B-i) are selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, and carboxylic acid esters of polyhydric alcohols selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol and glycerol.

Two-component system according to one of the preceding claims, wherein in component (A)

one, several or all of the alkali metal silicates (A-i) present are selected from the group consisting of sodium silicate, potassium silicate and mixtures thereof.

Two-component system according to one of the preceding claims, wherein component (A) comprises as further constituent

The two-component system according to claim 6, wherein in the component (A) the ratio

(Ai) of the total mass of all alkali metal silicates to

(A-iii) the total mass of the fillers

is in the range of 1: 1 to 1: 2, preferably 1: 1, 4 to 1: 1, 7.

8. Two-component system according to one of the preceding claims, wherein the ratio

the total mass of all alkali metal silicates (A-i) of component A.

the total mass of component (B-ii) of component B

in the range from 10: 1 to 70: 1, preferably in the range from 20: 1 to 50: 1, particularly preferably in the range from 30: 1 to 40: 1.

9. Two-component system according to one of the preceding claims, wherein component (A) comprises as further constituents:

(A-iv) one or more surfactants

and or

(A-V) one or more mineral oils.

10. Two-component system according to claim 9, wherein the sum of the mass fractions of the constituents

(A-iv) one or more surfactants and

(A-V) one or more mineral oils

2 wt .-% or less, based on the total mass of component (A).

1 1. A two-component system according to any one of the preceding claims, wherein the total content of the components (A) and (B) of the two-component system of organically bonded carbon 6 wt .-% or less, preferably 5.5% by weight or less , Particularly preferably 4 wt .-% or less, based on the total mass of components (A) and (B).

12. Two-component system according to one of the preceding claims, wherein the components (A) and (B) with regard to their composition and their mass Ratio are coordinated so that the mixture formed by mixing the components (A) and (B) has a pot life in the range of 2 minutes to 1 hour, preferably in the range of 3 minutes to 30 minutes.

13. A kit for producing an adhesive, comprising

- A two-component system according to one of claims 1 to 12

a static mixing device for mixing the components (A) and (B) of this two-component system.

14. Kit according to claim 13, wherein the static mixing device is part of a device for applying an adhesive to a splice. 15. Use of a kit according to one of claims 13 and 14 for producing an adhesive bond between objects to be joined.

Use according to claim 15, wherein the articles to be bonded by the adhesive bond at the splices contain one or more inorganic materials selected from the group of ceramic materials, in particular from the group consisting of oxides and silicates.

Use according to claim 15 or 16, wherein the objects to be joined by the adhesive joint are parts of a foundry mold, in particular cores or parts of cores, wherein preferably the parts to be joined of a foundry mold each contain mold primitives by curing one or more alkali metal silicates formed binder are bound.

Use of a static mixing apparatus for producing an adhesive, wherein the adhesive is prepared by mixing the components (A) and (B) of a two-component system according to any one of claims 1 to 12 in the static mixer.

A method of making an adhesive comprising the step

Mixing components (A) and (B) of a two-component system according to one of claims 1 to 12, preferably in a static mixing device.

20. A method for producing an adhesive bond between articles to be joined, comprising the steps of

Production of an adhesive according to a method according to claim 19

Allowing the adhesive to cure.

21. The method according to claim 20 for producing an adhesive bond between objects to be joined, wherein the adhesive has a pot life in the range of 2 minutes to 1 hour, preferably in the range of 3 minutes to 30 minutes.

22. The method of claim 20 or 21, wherein the objects to be joined by the adhesive bond at the splices one or more inorganic materials selected from the group of ceramic materials, in particular from the group consisting of oxides and silicates.

23. The method according to any one of claims 20 to 22 for producing an adhesive bond between objects to be joined, wherein the objects to be joined by the adhesive bond parts of a foundry mold, wherein preferably the parts to be joined a foundry mold each contain mold base materials by a by curing bonded binder formed by one or more alkali metal silicates.