MXPA00005462A - Quick hardening silicon materials with good adhesive properties - Google Patents

Abstract

The present invention relates to mixtures containing bi-functionally terminated diorganopolysiloxanes, aminosilane or oxime or alkoxy crosslinking agents, and optionally, filling materials, suitable additives, pigments, colorants, anti-oxidation pigments, anti-heat pigments, and light-protection pigments in addition to solvents and plasticizers. Said mixtures contain water and a catalyst in the form of an acidic or basic neutral salt as an accelerating cross-linking agent.

Description

QUICK HARDENING SILICONE MATERIALS WITH GOOD ADHESIVE PROPERTIES Description of the invention The present invention relates to equipment for the production of mixtures of at least bifunctionally terminated diorganopolysiloxanes, aminosilane crosslinking agents, as well as possible fillers, suitable additives, pigments, coloring materials, oxidation protective pigments, heat and light, as well as solvents and plasticizers. Such mixtures of organopolysiloxanes, also known as one-component, cold-curing silicone rubbers, usually cross-link at ambient temperature with uptake of water from the surrounding atmosphere to give elastic rubber polymers. As chain extenders and crosslinkers, the bifunctional aminosilane compounds are used, and preferably with higher functionality which, by reaction with polysiloxane or by hydrolysis, break the amines and thus initiate the formation of a macro-olecular network. After hardening has taken place, such masses are characterized by a good adhesion inherent to most surfaces of varied materials, and by a generally high stability towards the action of temperature, light, humidity, as well as the chemical products. The hardening of such single component polysiloxane mixtures which bind at room temperature with moisture uptake takes place comparatively slowly since the water necessary for the reaction must diffuse from the surrounding atmosphere into the mass . Therefore, the rate of hardening decreases with the progressive reaction inside the dough. In the case of low atmospheric humidity or in the case of an unfavorable disproportion of surface to volume of the silicone mass, the reaction can be very slow or, in the case of sealed spaces that are vapor-tight, come to a complete stop. The multiple possibilities of use per se of such silicones of hardening by atmospheric humidity as sealing material or adhesive are, especially in the case of use in industrial manufacture, limited due to the slow hardening. Admittedly, silicone rubber systems that harden rapidly at room temperature or also first at elevated temperature are known, but their use often fails because of the inherent poor adhesion, or also the comparatively low temperature stability of these products. However, if silicones are used that harden only slowly under the influence of atmospheric moisture, in the case of short cycle times desired for economic reasons, large intermediate storage for sealed or bonded parts is necessary in order to ensure the hardening. This intermediate hardening should possibly be additionally heated or moistened. Under certain circumstances, large numbers of parts are already produced in this way before the test for failure-freedom and function of the materials produced is first possible. The adhesions to large surfaces between the airtight surfaces for diffusion can, in practice, be carried out just with so few hardening silicones by atmospheric humidity, as the production of bodies formed in closed molds. If water is added in liquid form to the known aminosilane-containing hardening masses by atmospheric humidity, compared to cross-linking with atmospheric humidity, a certain hardening acceleration is achieved. However, this form of crosslinking leads to final products with material properties such as those obtained in the case of crosslinking purely with atmospheric moisture. On the contrary, the masses that result over time remain substantially softer, show poor inherent adhesion and remain still swollen for a very long time with the resulting amine as a fission product by crosslinking. Correspondingly, the amine odor, usually found to be extremely pleasant, also persists for a prolonged time. From German patent DE 4431489 it is known that the silicone masses for crosslinking by aminosilane harden rapidly when a paste containing water and an inorganic or organic compound which reacts with the amines with salt formation is added to the system. Organic and inorganic acids come into consideration as such compounds. The addition of these accelerating substances takes place immediately before the treatment of the dough. The acid reacts with the fission product, the amine, with the salt formation, whereby the equilibrium of the reaction is displaced to the side of the product. The salt formed remains in the polymer matrix and thus has a considerable influence on the final properties of the hardened polymer material. Especially affected by this is the temperature stability which is limited by the salt of the amine remaining in the matrix. . The basis for this is the possibility of splitting acidolytic or aminolytic of the polydimethylsiloxane structure at elevated temperatures. Thus, for example, after a few days of continuous tension at 250 ° C, a weakening of a silicone mass is observed rapidly hardened by the addition of oxalic acid dihydrate. In addition, by the reaction of oxalic acid with lime at elevated temperatures, a gas decomposition takes place. In this way, the task that forms the basis of The invention is to make available a construction equipment for the production of sealing masses and adhesives based on crosslinking polysiloxane mixtures with aminosilane, whereby it hardens within a short time, for example, within a few minutes to several hours, and independently of the ... surrounding atmospheric humidity, whereby, in addition to the typical characteristics of the previously known vulcanizates, such as, for example, the inherent adhesion, the mechanical properties and the stability, especially the stability At the temperature of the accelerated hardened silicone, they have to be improved. It has now been found that the replacement of the inorganic or organic acids of the known construction equipment which act as accelerating components for basic or acidic base stocks in the case of an acceleration action on the hardening comparable with the acids, provides a stability to the clearly improved temperature of the silicones polymerized under these conditions. Basic acid or neutral salts are compounds in which apparently all the ionizable hydrogen atoms of the acid are replaced with other cations, and all the OH groups of the cationic base are acid anions and, only via the different degree of dissociation of the acid. the underlying acids and bases, the aqueous solutions of the salts that react with acids or bases are obtained, especially in the case of 1 molar solutions with pH values lower than .5 or higher than 9, especially below 4 o In addition, it was found that, in addition to the aminosilane, the crosslinkers can also advantageously be used as components. The task that forms the basis of the invention is solved by the characteristics of the main claim and promoted by those of the dependent claims. Such construction equipment for the production of mixtures are characterized in that they contain at least the following components: A) 100 parts by weight of a diorganopolysiloxane at least bifunctionally terminated, whereby it is made up of a straight or branched chain of repeating units of the formula R1 I -Si-O- R¿ and - as shown in the subsequent case in the case of a linear chain - is terminated with the functional end groups Z.

R1 R1 Wherein the substituents mean: R1, R2: saturated or unsaturated hydrocarbon radicals with 1 to 15 carbon atoms, possibly substituted with halogen or cyano groups Z: -H, -OH, -OR1, -OSiR3 (NR4R5) 2, -C -Si- (ON = CR4R5) 3 and -O-Si- (OR3) 3 R3: hydrogen or saturated or unsaturated monovalent hydrocarbon or a hydrocarbon radical with 1 to carbon atoms. R4, R5: hydrogen and / or an aliphatic, cycloaliphatic or aromatic hydrocarbon radical, saturated or unsaturated with 1 to 15 carbon atoms, possibly substituted with halogen or cyano groups. B '0.1 to 20 parts by weight of an aminosilane or oxime or alkoxy crosslinker of the general formulas R3y-Si- (NR4R5) 4-4-5 and Ry-Si "(ON = CR4R °) 4-y R3y- YES- (OR3) 4-yc: 0.1 to 20 parts by weight of a catalyst in the form of a neutral acid or basic salt D) 0 to 20 parts by weight of water.

As an example for the radicals R1 and R2 of components A, any desired saturated alkyl radicals, such as methyl, ethyl, n-propyl, isopropyl, octyl, dodecyl, are to be named., octadecyl, but also cyclics such as cyclopentyl and cyclohexyl. In addition, unsaturated aliphatic and cycloaliphatic radicals, such as vinyl, allyl, cyclopentenyl or cyclohexenyl radicals and also aromatics, such as phenyl or naphthyl, and substituted aliphatic radicals such as for example benzyl or toluyl can be used. Within a polysiloxane, the radicals R1 and R2 may be the same or also of different construction. It is also possible to mix the branched and unbranched polysiloxanes with the above described construction and with different chain length. Preferably, polysiloxanes terminated with hydroxyl groups, designated α, β-dihydroxydiorganopolysiloxanes with methyl and phenyl radicals, are used. The mentioned radicals can also be used in the form of halogen or substituted with cyano. Examples for these are 1,1,1-trifluorotoluyl, β-cyanoethyl or the o-, - or p-chlorophenyl radicals. The viscosity of the diorganopolysiloxanes falls preferably in the range of 500 to 350,000 mPas. The radical R3 can, in addition to hydrogen, be of the same construction as the radicals R1 and R2. Preferably, simple alkyl radicals, such as methyl or ethyl, are used. The radicals R4 and R5 can be of the same construction as the radicals R1, R2 or R3, whereby one of the two radicals can also be hydrogen. The organoaminosilanes are preferably used, which are obtained, for example, from the reactions of methyltrichlorosilanes with primary, aliphatic or cycloaliphatic amines, especially with sec-butylamine or cyclohexylamine. As the component C, neutral acidic and basic salts are suitable, such as, for example, the neutral acid salts of aluminum, especially sulphate, chloride and nitrate, the aluminum alums of the ammonium ion and the alkali metals, preferably sodium and of potassium In addition, as advantageous representatives of the neutral acid salts, iron salts, especially iron sulphate II, iron III phosphate, iron alum of the ammonium ion, as well as iron II ammonium sulfate (Mohr salt) can be mentioned. . Basic neutral salts that act rapidly are, for example, trisodium phosphate and sodium metasilicate. The acidic or basic neutral salts can possibly also be used in combination. The component D can be added to the mixture not only in liquid form but also bound as water of crystallization, for example as sodium sulfate decahydrate, or enclosed in zeolites or also adsorbed on the surface of the filling materials, such as for example calcium carbonate. The addition of the component D takes place preferably in combination with the linked component C as water of crystallization. A mixture of components A to D can be added additional materials for the achievement of special properties. Those to be mentioned here are especially colored pigments and soluble colored materials, stabilizers against oxidation and heat action, dispersants, reaction catalysts, fungicides, adhesives, solvents, fire protection agents, pestifiers. (preferably silicone oil but also based on hydrocarbons), reinforcing fillers such as, for example, highly dispersed or precipitated silicas, graphite, carbon black, as well as passive fillers, such as, for example, calcium carbonate, silicates , quartz powder, glass fibers and carbon fibers, diatomaceous earth, metal powder, metal oxides, synthetic material powder, as well as hollow spheres of glass or synthetic material. As silicic acids, pyrogenic silicas, the polar surface of which is hydrophobicized, can preferably be used.

Mixtures of components A to D are not storage stable. Therefore, the components C and D necessary for the acceleration of the reaction are mixed with the mixture of components A and B immediately before use in a suitable mold, preferably pasted in silicone oils or polymers of component A. The present invention also relates to processes for the production of a sealing or adhesive mixture or the molding compound based on at least bifunctionally terminated diorganopolysiloxanes, and crosslinkers which are characterized in that: A) 100 parts by weight of such diorganopolysiloxane, by which it is made up of a linear or branched chain of repeating units of the formula R1 -Yes-O- R and, corresponding to the following special case of the linear chains according to the formula R1 RA Z-fSi-Oi Si-Z Rz R is finished with functional Z end groups, and where R1 R2: saturated or unsaturated hydrocarbon radicals with 1 to 15 carbon atoms, possibly substituted with halogen or cyano -H, -OH, -OR1, -OSÍR3 (NR4R5) 2, -C-Si- (ON = CR4R5) groups 3 and -0-Si- (OR3) 3 R- hydrogen or monovalent saturated or unsaturated hydrocarbon or a bldrocarbonoxy radical R 'R ~ hydrogen and / or an aliphatic, cycloaliphatic or aromatic hydrocarbon radical with 1 to 15 carbon atoms, possibly substituted with halogen or cyano groups. B '0.1 to 20 parts by weight of an aminosilane or oxime or alkoxy crosslinker of the general formulas R; -Si-: NR4R5: and R3y-Si- (ON = = CR4 R °: 4-y R3y-YES- (OR3) 4-y where Y = 0 or 1 and R3, R4 and R5 have the above meanings, as well as possibly colored pigments or soluble colored materials, stabilizers against oxidation and the action of heat, dispersants, reaction catalysts, fungicides, adhesives, solvents, fire protection agents, pipicants (preferably silicone oils but also pipicants) based on hydrocarbons), in addition, active reinforcing fillers, such as, for example, highly dispersed or precipitated silicas, graphite, carbon black, as well as passive fillers, such as, for example, calcium carbonate, silicates, quartz, glass and carbon fibers, diatomaceous earth, metal powder, metal oxide, synthetic material powder, as well as hollow spheres of glass or synthetic material, are mixed with each other and are added immediately before use. C) 0.1 to 20 parts by weight of a catalyst in the form of an acidic or basic neutral salt, D) 0 to 20 parts by weight of water, possibly pasted in silicone oil or polymers.

The mixtures prepared with the aid of the construction equipment according to the invention are preferably hardened at room temperature in 20 minutes to 3 hours to give a solid mass, free of adhesion and cuttable. The increased temperature in the case of hardening (approximately 40 ° C) gives rise to an additional acceleration effect. Silicone blends adhere on their own to substrates made of glass, ceramic, wood, concrete, plasters, metals and synthetic materials. A fast-built inherent adhesion is achieved especially in glass, metals and synthetic materials with a polar surface. Thus, the mixtures according to the invention are advantageously used as adhesive or sealing materials, as protective coverings for electrical insulation, as pouring masses for electrical and electronic construction parts but also as molding compositions for the production of impressions or other parts molded that are usefully produced from elastomers. In the subsequent, the invention is explained in more detail based on an Example.Example 100 parts by weight of a component I consisting of: 100 parts by weight of an α, β-dihydroxydimethylpolysiloxane with a viscosity of 20,000 mPas, 18 parts by weight of a highly dispersed silicic acid with a specific surface area according to BET of approximately 110 m2 / g 15 parts by weight of a calcium carbonate filler material, 8 parts by weight of tris- (cycloalkylamino) -methylsilane are mixed homogeneously together with 25 parts by weight of a component II consisting of : 100 parts by weight of an α, β-dihydroxydimethepolysiloxane with a viscosity of 20,000 mPas, 9 parts by weight of a highly dispersed silicic acid with a specific surface area according to BET of approximately 150 m2 / g, 2.5 a 3 parts by weight of an ammonium alum aluminum dodecahydrate greater than 100 μm.

The mixture of silicone produced from the components of a construction equipment according to the invention was hardened or cuttable after approximately 25 minutes at room temperature, to the exclusion of atmospheric humidity and, after one hour, achieved a Shore hardness from about 20-25. The final hardness, measured after 7 days, reaches a Shore A of about 40. Under these conditions, both components remain storage stable pastes. The mass shows a surprising stability to the temperature, under temperature conditions of up to 250 ° C. The loss in weight in the case of a temperature tension of 250 ° C reaches, after one day, approximately 5%, caused by the emergence of the excision product, after 7 days at 8% and, after 42 days, drops by approximately 12%. In addition, an inherent adhesion quickly constituted on various substrates, especially glass, metals and synthetic materials with polar surface, was achieved. The initial adhesion on these substrates is already so strong already after 30 minutes that a pull of the mass from the adhesion surface is only possible with mechanical destruction. The adhered parts can already be subjected to mechanical stress after 30 minutes. In the following Table, additional experiments are given with other acidic or basic neutral salts, whereby the components I and II, as well as the production, were carried out according to the previous Example. The amount of water introduced via the accelerating substance C thus represents approximately 0.3 g / 100 g of component I, which is sufficiently complete or preponderantly to hydrolyze the added crosslinker (component B). A separate addition of water (component D) is not necessary.

Through the use of acidic or basic neutral salts, systems based on oxime or alkoxy crosslinker can also be accelerated.

Claims (11)

1. Construction equipment for the production of fast-hardening aminosilane crosslinking silicone masses, at least bifunctionally terminated diorganopolysiloxanes, aminosilane crosslinkers, as well as possibly filler materials, suitable additives and pigments, containing the following components: A) 100 parts by weight of a diorganopolysiloxane at least bifunctionally terminated, wherein this polysiloxane is constituted by a linear or branched chain of repeating units of the formula R1 I -Si-O-R ' and contains at least two Z end groups with Z: -H, -OH, -OR1, -OSiR3 (NR4R5) 2, R1, R2: saturated or unsaturated hydrocarbon radicals with carbon atoms possibly substituted with halogen or cyano groups, B ) 0.1 to 20 parts by weight of a crosslinker, C) 0.1 to 20 parts by weight of an accelerator, D) 0 to 20 parts by weight of water, characterized in that the accelerator in component C is an acid or basic neutral salt and component B an aminosilane crosslinker of the general formula: R y-YES- (NR4R5) 4-, where y = 0 or 1, with R3: hydrogen or monovalent saturated or unsaturated hydrocarbon or a radical tetracarbonoxy and R4, R5: hydrogen and / or an aliphatic, cycloaliphatic or aromatic hydrocarbon radical, saturated or unsaturated, with 1 to 15 carbon atoms carbon, possibly substituted with halogen or cyano groups; or an oxime or alkoxy crosslinker of the general formula: R3y-Si- (ONCR4R5) 4-y R3y-YES- (OR3) 4-y where y = 0 or 1 and R3, R4 and R have the above meanings.

2. Construction equipment according to claim 1, characterized in that the accelerator component C is contained in water in the form that contains crystallization.

3. Construction equipment according to claim 1 to 2, characterized in that, as the component D, the water of the crystallization hydrate materials or the water absorbed on zeolites or silica gels or adsorbed in the filling material is used.

4. Construction equipment according to claim 1 to 3, characterized in that additionally colored pigments or soluble coloring materials, stabilizers against oxidation and heat action, dispersants, reaction catalysts, fungicides, adhesives, solvents, anti-caustic agents are contained. fire, plasticizers (preferably silicone oils but also hydrocarbon-based plasticizers), additional active agents, reinforcing fillers, such as, for example, highly dispersed or precipitated silicas, graphite, carbon black, as well as passive fillers , such as for example calcium carbonate, silicates, quartz powder, glass and carbon fibers, diatomaceous earth, metal powder, metal oxides, plastic powder, as well as hollow glass or plastic spheres in the Components A - D.

5. Construction equipment according to claim 1 to 4, characterized in that, as a component of diorganopolysiloxane A, an α, β-dihydroxydiorganopolysiloxane is used.

6. Process for the production of a sealing or adhesive mixture based on diorganopolysiloxanes and aminosilane or oxime or alkoxy crosslinkers, characterized in that the components A and B according to claim 1 are mixed to give a first premix and the components C and D to give a second premix and, shortly before use, the two premixes combine to give the effective sealing and adhesive mixture.

7. Process according to claim 6, characterized in that, as component C, a compound according to claim 2 is used and, as component D, a mixture according to claim 2 or 3.

8. Process according to claims 6 to 7, characterized in that the components C and / or D, possibly in combination with the materials of claim 4, are in the form of a paste and possibly a plasticizer based on silicone or a polymer of diorganopolysiloxane is added in accordance with claim 1.

9. Process according to claims 6 to 8, characterized in that a,? -dihydroxydiorganopolysiloxane is used.

10. The use of the mixtures of construction equipment according to claim 1 to 5, as sealant or adhesive material.

11. The use of the mixtures of construction equipment according to claims 1 to 5, as the molding compound.